KR101122598B1 - Apparatus for uniform charging battery - Google Patents

Abstract

The battery cell equalizing charging device according to the present invention relates to a battery equalizing charging device for equally charging each battery cell of a battery tank in which a plurality of battery cells are connected in series with each other, and a control method thereof. A DC / DC converter receiving a charging voltage from the battery cells disposed in each of the battery cells and boosting the voltage; a DC storage means for storing the boosted output voltage of the DC / DC converter; and a power stored in the DC storage means. By including a recovery passage means for supplying to the tank, it is possible to recover the surcharge power generated by the overcharge of the battery cell, high charging efficiency and equally charged each cell connected in series to prevent overcharge, overdischarge, low charge phenomenon, etc. Can be caused by charge imbalance. Prevent damage or explosion of the battery and can extend the life of the battery system (trillion).

Batteries, Battery Cells, Charging, DC / DC Converters, Balancing

Description

Battery Cell Uniform Charging Device {APPARATUS FOR UNIFORM CHARGING BATTERY}

The present invention relates to an apparatus for equalizing a battery cell and a method of controlling the same. More specifically, the present invention relates to recovering surplus power of overcharged battery cell power or performing supplemental charging on a battery cell that is undercharged in a process of collective charging. The present invention relates to a battery cell equalizing charging device that enables even battery charging quickly, and a control method thereof.

High power density lithium, such as large-capacity lithium-ion, lithium polymer, and nickel-hydrogen batteries, for the purpose of increasing driving speed and maximum driving distance for electric vehicles such as hybrid (HEV) vehicles, electric vehicles, electric bicycles, and golf-carts A series of batteries is adopted.

Even in the case of other secondary batteries, when the cell voltage is imbalanced, the aging of the battery system is accelerated and the lifespan is shortened, such as a decrease in capacity. However, in the case of a lithium battery pack, when the cell voltage is imbalanced, a sudden change in characteristics is caused. May explode.

If the charge / discharge cycle increases by using a battery system (pack) composed of a plurality of battery cells connected in series for a long time, the characteristic factors of each battery cell are not equal to each other, and thus, the charge voltage of the battery cells is unbalanced. Becomes Therefore, as a means to prevent this, the cell equalization charging (Cell Balancing) control function is required.

Individual charging device facility for each battery cell (mono block) to charge a battery tank (called a "pack" or "stack" in a small configuration) configured by connecting a plurality of battery cells in series It is a reality that is difficult. Therefore, in general, as shown in FIG. 1, a charging method of collectively charging a plurality of battery cells by connecting outputs of a charging device to both positive and negative terminals of a battery tank terminal (batch charging). This is widely used.

The conventional charging device including the battery tank 10, the voltage detector 20, the current detector 30, the charge control means 40, the constant voltage / constant current control means 50, the power supply unit 60 is a battery tank Regardless of the difference in characteristics of each of the battery cells constituting the (stack), it is designed to charge by supplying the charging current collectively. In this batch charging method, since charging is performed in a batch without considering capacity differences between battery cells or differences in internal resistance, battery cells that are overcharged or battery cells that stop charging when not fully charged are present. A vulnerability exists in

In addition, due to manufacturing errors, each battery cell may be manufactured with different charging and discharging characteristics. Therefore, when a plurality of cells connected in series are collectively charged, voltage deviations between the cells may reach explosive levels. do.

In addition, the charging non-uniformity between the battery cells is deeper when the depth of discharge (DOD) is high, eventually causing overcharging and adversely affect the battery life, and moreover, in the case of lithium ion batteries, It becomes a factor.

The present invention has been made to solve the above problems, and can be equally charged by recovering excess charging power of an overcharged battery cell or performing replenishment of an undercharged battery cell in a battery tank in which batch charging is performed. An object of the present invention is to provide a battery cell equalizing charging device and a method thereof.

In order to achieve the above object, the battery cell equalizing charging device according to the present invention is a battery equalizing charging device that equally charges each battery cell of a battery tank in which a plurality of battery cells are connected and connected in series, and disposed in each of the battery cells. And a DC / DC converter which receives the charging voltage from the battery cell and performs step-up conversion, a direct current storage means for storing the boosted output voltage of the DC / DC converter, and supplying power stored in the direct current storage means to the battery tank. Recovery passage means.

In this case, the battery cell may be an overcharged battery cell, the DC / DC converter is an isolated converter or step-down buck (buck), step-up, including a transformer, such as a conventional flyback, forward converter It may be configured to include any one of the non-isolated converter, such as a boost, step-up / step-up Buck-Boost converter.

In addition, the DC storage means may be a device or device capable of storing DC power, such as a DC electrolytic capacitor or a supercapacitor, or a DC electrolytic capacitor designed on the output side of the DC / DC converter, and may include at least one or more of them. .

In this case, the recovery passage means may be a rectifying element such as a diode or a device consisting of them, connected to the positive and negative terminals of the battery tank or rectifying means in which the plurality of cells are collectively charged or connected in part of the battery tank When connected to a stage (string) and the voltage of the DC storage means is increased, the current may flow to the battery side.

In addition, the battery cell equalizing charging device according to the present invention may further include a cell voltage measuring means for measuring the charge voltage of the battery cell and a cell selection control means for selecting the overcharged or undercharged battery cells according to the measurement result. have.

The DC / DC converter includes a first switch operable to charge a direct current storage means such as a capacitor connected to the secondary side by step-up converting the overcharged surplus charge amount of each cell when a plurality of cells are connected in series with each other. The first switch may be driven by a PWM control signal in the DC / DC converter or by a command of the cell selection control means. The DC / DC converter is a transformer disposed between the battery cell and the direct current storage means, a first switch connected in series with the transformer and the battery cell, and the direct current storage means, and the transformer and the direct current storage. It may comprise a second diode connected in series with the means.

In addition, the DC / DC converter is operated in the opposite direction (reverse direction) in order to recharge the undercharged cells by stepping down or converting the amount of power stored in the direct current storage means or the amount of power supplied from the rectifying means, and in parallel with the second diode. It is preferable to further include a second switch and a first diode directed to the battery cell and connected in parallel to the first switch, and by configuring in this way it is possible to maximize the industrial use effect of the present invention, It may be preferable that the first switch or the second switch is driven by a PWM control signal in the DC / DC converter or by a command of the cell selection control means.

In addition, the DC / DC converter is driven by a command of the cell selection control means and is driven by a command of the first switch and the cell selection control means for receiving a charging voltage from the overcharged battery cell and boosting the direct current. The method may further include a second switch for stepping down the power stored in the storage means to supply a charging current to the undercharged battery cell.

The DC / DC converter may include a transformer disposed between the battery cell and the direct current storage means, a first switch connected in series to the transformer and the battery cell, and a first serial connection to the transformer and the direct current storage means. A second diode comprising two diodes, directed to the anode of the battery cell and, if necessary, driven opposite to the first switch and connected in parallel with the first switch and connected in parallel with the second diode; It may further include.

The DC / DC converter further includes a first switch connected to the battery cell in a parallel configuration, directing an anode of the DC storage means between the first switch and the DC storage means and in series with the DC storage means. A second diode connected, and an inductor connected in series with the second diode between the battery cell and the direct current storage means, and The display device may further include a first diode directed toward the battery cell and connected in parallel with the first switch, and a second switch connected in parallel with the second diode and driven opposite to the first switch.

The cell selection control unit may further include a function of controlling a pulse width modulation (PWM) of at least one of the first switch and the second switch.

On the other hand, the battery cell equalizing charge device according to the present invention is a cell voltage measuring means for measuring the charge voltage of the battery cells constituting the battery tank, a cell selection control means for selecting the overcharged battery cells according to the measurement result, the cell selection A switching means driven to connect the selected battery cell to a DC / DC converter according to a command of a control means, a DC / DC converter receiving and boosting a charging voltage from the connected battery cell according to driving of the switching means, the DC DC storage means for storing the boosted output voltage of the / DC converter and recovery path means for supplying the power stored in the DC storage means to the battery tank.

Here, the cell selection control means selects a battery cell according to the measurement result, and the DC / DC converter receives a charging voltage from the overcharged battery cell and boosts it when the selected battery cell is an overcharged battery cell. It may include a first switch required to convert.

The cell selection control unit may further have a role of selecting an overcharged or undercharged battery cell according to a measurement result, and the DC / DC converter may perform the overcharge when the selected battery cell is an overcharged battery cell. It may include a first switch for receiving a charging voltage from the battery cell to boost the step and the direct current storage means and a second diode connected in series from the inductor or transformer. The method may further include a second switch for step-down converting power stored in the direct current storage means to supply the undercharged battery cell when the selected battery cell is undercharged.

Here, the DC / DC converter is a transformer disposed between the switching means and the direct current storage means, the first switch connected in series with the transformer and the switching means and the anode of the direct current storage means and direct current storage A second diode connected in series with the means, the first diode being directed towards the switching means and connected in parallel with the first switch and the second diode connected in parallel with the second diode and driven opposite to the first switch. It may further include two switches.

The DC / DC converter may further include a first switch disposed in parallel to the switching means and the direct current storage means, and connected in series to the switching means and the direct current storage means between the switching means and the first switch. An inductor, a second diode directed toward the anode of said direct current storage means and connected in series with said direct current storage means between said first switch and said direct current storage means; And a second switch directed toward the anode of the battery cell and connected in parallel to the first switch, and a second switch connected in parallel to the second diode and driven opposite to the first switch.

The apparatus may further include a controller configured to drive the first switch and the second switch, and the controller may further control a pulse width modulation (PWM) control of at least one of the first switch and the second switch. It may include.

On the other hand, the battery cell equal charging method according to the invention, measuring the battery cell voltage of the battery tank, comparing the measurement result with a predetermined full charge voltage of the battery cell and the average voltage of the battery cell, the cell Stepping up the overcharged power of the battery cell whose voltage is higher than the full charge voltage to perform a power supply to a direct current storage means; when the state where the cell voltage is equal to the full charge voltage is maintained for a predetermined time Terminating.

In addition, the battery cell equal charging method according to the present invention, the battery cell measured the cell voltage is lower than the average voltage is supplied with power from the direct current storage means to perform the replenishment of the insufficiently charged battery cells It may further include.

As described above, the battery cell equalizing charging device according to the present invention recovers power of an overcharged battery cell and supplies it back to the battery tank, thereby preventing overcharging and improving the charging efficiency of the battery tank. The charging voltage of the battery cells is equalized.

In addition, the charging voltage of each battery cell may be equally performed in the charging process by supplying a charging current to the undercharged battery cells.

Therefore, according to the present invention, it is possible to stably supply charging power when charging a secondary battery such as a lithium-based battery pack, and further, to operate an electric vehicle or a DC power storage device in which a corresponding battery pack (battery pack) is used. Safety and reliability can be secured.

The batch charging described in the present specification provides a charging method for collectively charging a plurality of battery cells constituting the battery tank by connecting outputs of the charging device to both positive and negative terminals of the battery tank terminal. Refer.

Hereinafter, a battery cell equalizing charging device and method according to the present invention will be described in more detail with reference to the accompanying drawings.

2 is a schematic view showing a battery cell equalizing charge device according to the present invention.

The battery cell equalizing charging device shown in FIG. 2 is a battery equalizing charging device that equally charges each of the battery cells of the battery tank 110 in which a plurality of battery cells E1 to En are connected in series to each other. A DC / DC converter 130 disposed in each of the battery cells to receive and convert a charging voltage from the battery cell, DC storage means 140 for storing the boosted output voltage of the DC / DC converter, and stored in the DC storage means. And recovery passage means 160 for supplying electric power to the battery tank.

Each battery cell may be charged collectively by the rectifying means 190 for supplying power to the battery tank (110). At this time, as described above, the charging voltage of each battery cell is different depending on the characteristic difference of each cell.

The DC / DC converter 130 is an element that receives a charging voltage from each battery cell constituting the battery tank and boosts it. That is, the DC / DC converter performs a function of flowing out the overcharged voltage to the battery cell to the outside. Since draining power of a normally charged battery cell to the outside violates the basic principle of battery charging, the DC / DC converter is preferably driven according to a predetermined situation or condition.

Accordingly, the DC / DC converter 130 may be configured to be driven when the charging voltage of each battery cell is greater than or equal to a preset value to receive and boost the charging voltage of the battery cell. For example, when the preset value is set to the full charge allowable voltage and the charge voltage of the battery cell exceeds the full charge allowable voltage, the DC / DC converter is driven to prevent the charge voltage of the battery cell from exceeding the full charge allowable voltage. Can be controlled.

To this end, it is necessary to identify battery cells that have been charged above the first predetermined value or the full charge voltage (full charge allowable voltage), that is, overcharged battery cells.

As shown in FIG. 3, a cell voltage measuring means 120 for measuring a charging voltage of a battery cell and a cell selection control means 150 for driving a DC / DC converter disposed in a battery cell overcharged by the cell voltage measuring means are provided. Although it may be arranged separately, a device that passes excess power when a predetermined voltage is applied, such as a constant voltage device such as a zener diode, may be included in the DC / DC converter. In the latter case, the constant voltage maintenance reference value of the constant voltage element should satisfy the full charge voltage.

Accordingly, the DC / DC converter may receive the charging voltage from the battery cell charged above the first predetermined voltage or the full charge voltage without increasing the cell voltage measuring means and the cell selection control means.

The DC storage means 140 is composed of a capacitor (capacitor) in the DC / DC converter or an external capacitor to store a predetermined power. In this embodiment, since the direct current storage means stores the boosted output voltage of the DC / DC converter, as a result, the surplus charging voltage leaked out through the DC / DC converter in the battery cell is stored in the direct current storage means.

Meanwhile, the DC storage means may be a device or device capable of storing DC power, such as a DC electrolytic capacitor or a supercapacitor, or a DC electrolytic capacitor designed on the output side of the DC / DC converter, and may include at least one. That is, the direct current storage means may be formed separately from the DC / DC converter or may be integrally formed with the DC / DC converter, and the first direct current storage means formed separately from the DC / DC converter and the second direct current formed integrally with the DC / DC converter It may comprise all of the storage means.

The recovery passage means 160 is an element for recovering the surplus charging voltage stored in the direct current storage means and supplying it to the battery tank again. When the voltage of the DC storage means is increased by being connected to the positive and negative terminals of the battery tank or rectifying means that the plurality of cells are collectively charged or connected to some series connection terminal (string) of the battery tank, the current flows to the battery side. May be arranged to flow. 2 to 5 or 10 to 13 shows that the recovery passage means 160 has one diode rectifying element disposed at both the positive and negative poles of the battery tank, but is variously connected to some series connection terminals (strings). It is possible to change.

According to the above configuration, the battery cell equalizing charging device according to the present embodiment boosts the charge voltage of the overcharged battery cells with a DC / DC converter, stores them in the DC storage means, and supplies them to the battery tank through the recovery passage means. That is, according to this action, there is no overcharged battery cell at the end of the charge, and all battery cells are equally charged. For reference, when there are a plurality of overcharged battery cells, a plurality of DC / DC converters disposed in each battery cell may also be driven.

On the other hand, as mentioned above, through the cell voltage measuring means and the cell selection control means, the DC / DC converter may be selected and driven independently as needed. In this case, PWM control can be applied to the DC / DC converter, thereby easily controlling the power flowing from the overcharged battery cell to the DC / DC converter. As a result, the charging voltage of each battery cell can be equalized more reliably.

FIG. 3 illustrates such a configuration, which further includes a cell voltage measuring means 120 for measuring a charging voltage of a battery cell, and a cell selection control means 150 for selecting an overcharged battery cell according to a measurement result. . At this time, the DC / DC converters are selected by the command of the cell selection control means and are driven independently of each other.

The cell voltage measuring unit 120 measures the charging voltage of each of the battery cells constituting the battery tank as an element measuring the charging voltage of the battery cell. To this end, the cell voltage measuring means may include at least one of a voltage measuring means or a current measuring means connected to each battery cell. In addition, an element that clamps to maintain a constant voltage when a predetermined voltage or more is applied, such as a Zener diode.

The cell selection control means 150 determines the overcharged battery cell by comparing the charging voltage of the battery cell measured by the cell voltage measuring means with a preset full charge allowable voltage. If an overcharged battery cell is present, the overcharged battery cell is selected. In addition, the cell selection control means may instruct the selected DC / DC converter to be driven.

That is, as an embodiment of the present invention, the driving of the DC / DC converter may be determined by the cell selection control means. This configuration enables PWM control of the DC / DC converter. When the cell voltage measuring means is constituted by a zener diode or the like, or controlled by the PWM control circuit of the DC / DC converter (configurable to drive at a certain voltage), the cell selection control means needs to know the full charge voltage separately. There is no. Therefore, in this case, the cell voltage measuring means may be integrally formed with the cell selection control means. The cell selection control means may configure a circuit to perform PWM control based on the voltage transferred through the zener diode.

The selection of the battery cell may be by a switch disposed between the battery cell and the DC / DC converter disposed in the battery cell, or may be by a first switch formed in the DC / DC converter. In the latter case, the overcharged battery cell selection of the cell selection control means and the command to the DC / DC converter may be the same signal. PWM control of the DC / DC converter will be implemented as control for the first switch. In summary, cell voltage measuring means for measuring the charging voltage of the battery cell, the cell selection control means for selecting an overcharged battery cell according to the measurement result may be further included, wherein the DC / DC converter is a plurality of cells In the case of being connected in series with each other, the first switch comprises a first switch that is stepped up to charge the DC storage means such as a capacitor connected to the secondary side by step-up converting the overcharged excess charge of each cell; It can be driven by the command of the cell selection control means.

Specifically, as shown in FIG. 14, the DC / DC converter 130 is serially connected to the transformer Tn, the transformer Tn, and the battery cell En disposed between the battery cell En and the direct current storage means Cn. A first diode (Spn) connected to the direct current storage means (Cn) and a second diode (D2n) connected in series to the transformer (Tn) and the direct current storage means (Cn), the battery cell (anode) And a first diode D1n directing and connected in parallel to the first switch.

Hereinafter, embodiments in which a second switch connected to the second diode appears will be described. It is noted that except for the second switch in each embodiment, it may correspond to the same configuration as in the present embodiment.

The above relates to the storage of surplus power in the DC storage means from the overcharged battery cells. On the contrary, the battery cells that are undercharged by being supplied to the battery cells by using the power stored in the DC storage means or the power supplied from the rectifying means are supplied. You can also make a supplemental charge.

In order to step down the power stored in the DC storage means and supply the battery cells undercharged, it is necessary to identify the undercharged battery cells or the battery cells charged lower than the average voltage of each battery cell voltage. Cell voltage measuring means 120 performing a function of measuring a charging voltage and cell selection control means 150 for selecting a battery cell that is undercharged according to the measurement result are disposed. At this time, the DC / DC converters connected to the undercharged battery cells by the command of the cell selection control means are selected and driven independently of each other.

In this case, the DC / DC converter includes a second switch and a first diode directed to the battery cell (anode), and by stepping down, converts the power stored in the DC storage means to supply the charging current to the undercharged battery cell. The second switch may be driven by the command of the cell selection control means. In this case, the configuration of storing the surplus power of the overcharged battery cells in the DC storage means may not require the cell voltage measuring means and the cell selection control means as shown in FIG. 2, and the cell voltage measuring means as shown in FIG. 3. And cell selection control means.

The latter case may include a DC / DC converter, a direct current storage means, a recovery passage means, a cell voltage measurement means, and a cell selection control means, wherein the cell selection control means depends on the measurement result by the cell voltage measurement means. It should be possible to select an overcharged or undercharged battery cell. On the other hand, as needed, the second switch can be PWM controlled by the cell selection control means.

In summary, the DC / DC converter reverses (reverses) to replenish the insufficiently charged cells by stepping down or converting the amount of power stored in the DC storage means or the power supplied from the rectifying means for supplying power to the battery tank. And a second switch configured to be operated by the second switch, wherein the second switch can be driven by a command of the cell selection control means.

In addition, the DC / DC converter may be driven by the command of the cell selection control means and is driven by the command of the first switch and the cell selection control means necessary to receive and boost the charging voltage from the overcharged battery cell and store the direct current. And a second switch necessary to step down the power stored in the means to supply the charging current to the undercharged battery cell.

In addition, a second switch and a battery cell (anode) required to supply a charging current to the undercharged battery cell by step-down converting at least one of the power stored in the DC storage means or the power of the rectifying means for supplying power to the battery tank. It may also be composed of only the first diode arranged to face. According to this, when the second switch is turned on, power is supplied from the direct current storage means to the battery cell.

The DC / DC converter may be configured in various ways including the first switch and the second switch. Examples of the DC / DC converter are illustrated in FIGS. 4, 5, 12, 13, 15, and 16.

In the above embodiments, the same technical effect may be obtained by changing the connection positions of the first switch and the transformer.

Figure 4 is a schematic diagram showing a battery cell equalizing charge device according to the present invention including an example of a DC / DC converter.

The battery cell equalizing apparatus shown in FIG. 4 includes cell voltage measuring means (not shown), cell selection control means (not shown), DC / DC converter 130, recovery passage means 160, and DC storage means 140. It includes.

The DC / DC converter 130 is installed for each unit battery cell constituting the battery tank, and the primary circuit is configured in series, respectively, and the output of each DC / DC converter has a relatively large output capacitor (Co). While commonly connected to the direct current storage means 140 composed of the back and the like is electrically separated from the battery cells by the transformer (T ₁ ~ Tn).

The DC / DC converter 130 directs the transformers T1 to Tn disposed between the battery cells and the DC storage means Co 140, the first switches Sp1 to Spn connected in series with the transformers T1 to Tn and the battery cells, and the battery cells. And a first diode D1 ₁ to D1n connected in parallel to the first switches Sp1 to Spn, and a second diode D2 ₁ to connected in series between the transformer T1 to Tn and the direct current storage means Co and directed toward the direct current storage means Co. D2n and second switches Ss1 to Ssn connected in parallel to the second diodes D2 ₁ to D2n and operating opposite to the first switches Sp1 to Spn. The second switch is an element for supplying power of the rectifying means or the battery assembly to the undercharged battery cell. Therefore, if the second switch is omitted, power supply from the battery cell or the rectifying means to the battery cell is impossible, and only the surplus power recovery from the battery cell to the battery cell is possible.

In describing the first diode, the second diode, the first switch, and the second switch, the term “directive” is used to indicate the arrangement of the diode or the switch having the directivity. For example, "directing a battery cell" means that the current is arranged to flow toward the battery cell.

Here, the first switches Sp1 to Spn and the second switches Ss1 to Ssn can be driven by the command of the cell selection control means, and are driven opposite to each other for the purpose of step-up or step-down conversion. That is, when the first switches Sp1 to Spn are turned on, the second switches Ss1 to Ssn disposed in the same DC / DC converter should be turned off, and when the first switches Sp to Spn are turned off, the second switches Ss1 to Spn are turned off. Ssn is turned on. Note that the on / off does not mean that the switch is energized / closed, but whether the PWM drive. Therefore, when the first switch is repeatedly energized / closed by the PWM control operation, the second switch is not closed or energized in reverse, but is in a closed state (it may be energized by the second diode depending on the circuit configuration). Is maintained. Of course, the driving of the first and second switches is not normally performed, but is performed when the surplus power recovery command for the overcharged battery cell or the charge command for the undercharged battery cell is issued by the cell selection control means. do.

If the battery cell E1 is overcharged, the cell selection control means drives the first switch Sp1 and turns off the second switch Ss1. In the state where the first switch Sp1 is PWM driven and the second switch Ss1 is off, the current flows only from the battery cell E1 in the direction of the direct current storage means, so that the charging voltage of the battery cell E1 is boosted by the transformer T1 to the direct current storage device. Stored.

If the battery cell E1 is undercharged, the cell selection control means turns off the first switch Sp1 and PWM-drives the second switch Ss1. In this case, since a current flows from the rectifying means or the direct current storage means to the battery cell E1, the power rectified by the rectifying means or the power stored in the direct current storage device is stepped down through the transformer T1 and supplied to the battery cell E1.

For reference, when the first switch and the second switch are composed of electronic switches such as FETs and TRs, the first switches and the second switches may have a directionality like a diode. In this case, as shown in FIG. 4 or FIG. 12, the first switch is arranged to face the cathode of the battery cell in parallel with the first diode, and the second switch is directed to the cathode of the DC storage means in parallel with the second diode. It is preferable to arrange.

The recovery passage means 160 provides a passage through which the electric power accumulated in the direct current storage means can be supplied to the battery tank again. The recovery passage means 160 is connected to both ends of a battery tank consisting of a plurality of battery cells or to some series connection end (string) of the battery tank and disposed in each battery cell through the connection of the recovery passage means 160. The DC / DC converter can be controlled independently without being affected by the battery bath and the series connection string.

That is, since the positive and negative terminals of the DC storage means are connected to the battery tank through the anode side diode and the cathode side diode which are the components of the recovery passage means 160, the outputs of the respective DC / DC converters are commonly connected. The output side of the direct current storage means is blocked from the battery cell voltage connected through the recovery passage means 160. Therefore, since the output of each DC / DC converter is not affected by the voltage of the battery tank or string, each of the DC / DC converter can be controlled independently, the surplus charging current flows into the DC storage means side and the DC When the voltage of the storage means becomes higher than the charging voltage of the battery tank, discharge (current flow) is started to the battery tank side, and the voltage rise of the DC storage means is limited. Placing a diode as a component of the recovery passage means 160 on the battery anode and cathode sides enables the diode to be used with low breakdown voltage and further ensures blocking from the battery bath voltage.
In addition, the DC / DC converters may each include a capacitor capable of recovering energy stored in the circuit or filtering (filtering) ripple noise by a magnetizing current during the conversion control of the internal output circuit stage. The direct current storage means may be commonly connected to the output side of the field. Therefore, the DC / DC converters can be converted and operated even during the period in which the recovery passage means 160 is off, and the overcharged battery cell can be equalized effectively.

Therefore, the voltage of the DC storage means arranged in series through the recovery passage means 160 in the battery tank must be designed to be at least higher than the voltage of the two battery cells, and the transformers T1 to Tn have the voltage step-up / down voltage in consideration of such a voltage relationship. The primary secondary winding ratio should be taken into account.

The DC / DC converter may further comprise auxiliary DC storage means C1 to Cn between the transformers T1 to Tn and the direct current storage means Co.

5 is a schematic view showing a battery cell equalizing charge device according to the present invention including another example of a DC / DC converter.

The battery cell equalizing charging device shown in FIG. 5 includes cell voltage measuring means (not shown), cell selection control means (not shown), DC / DC converter 230, power recovery means 160, and DC storage means Co (140). ) Is included.

The DC / DC converter 230 is an inductor L1 to Ln connected in series with a battery cell (anode) and a direct current storage means Co, and a parallel form between the inductor and the direct current storage means Co (to distinguish from the parallel relationship between a diode and a switch. First switch Sp1 to Spn arranged in a macroscopic parallel connection) and a second diode directed in direct contact with the direct current storage means between the first switch and the direct current storage means and connected in series with the inductor and the direct current storage means. D2 ₁ to D2n are included.

The first diode D1 ₁ ~ D1n and second switches are connected in parallel with the second diode is opposed to the drive of the first switch Sp1 ~ Spn direct the positive electrode of the battery cell and connected in parallel to the first switch Sp1 ~ Spn Ss1 to Ssn may be further included. In this case, the battery cell that is insufficiently charged by step-down converting at least one of the power stored in the DC storage means or the power of the rectifying means for supplying power to the battery tank by the driving of the second switch. Charging current can be supplied.

In order to electrically block each DC / DC converter, cathodes may be jointly connected to the cathode side of the DC storage means Co, and the anode may further include diodes D3 ₁ to D3n connected to the first switches Sp1 to Spn, respectively.

In the above, when the DC / DC converter includes at least one switch of the first switch and the second switch, the cell selection control unit may perform at least one of the first switch and the second switch by PWM (Pulse Width Modulation). ) May further include a function for controlling, which may be specifically implemented by FIGS. 6 to 8.

6 is a schematic diagram showing a cell selection control means and a PWM control circuit of a controller to be described later in the battery cell equalizing charging device according to the present invention, and FIG.

The differential amplifier circuit 51 inputs an overcharged or undercharged battery cell voltage to differentially amplify the difference between the battery cell voltage e _n and the set voltage Vref to be controlled and outputs its output signal to the comparator 52. do. By comparing the triangular / sawtooth wave signal generated by the triangular wave / sawtooth wave generator 53 and the output signal of the differential amplifier circuit 51 in the comparator 52, the PWM conduction (On / Off) width is independently determined for each battery cell. PWM control signal can be obtained. In this case, the set voltage Vref may be a full charge allowable voltage of the battery cell or a divided voltage thereof.

As shown in FIG. 7, when the battery cell voltage e _n is lower than the set voltage (Vref, eg, 4.2 V in the case of a lithium ion battery), the output signal level of the differential amplifier circuit 51 is -K (e _n -Vref). According to the relation of + 5V (here, the triangle wave signal peak value is 5V), it becomes more than 5V and becomes larger than the triangle wave signal, so no PWM pulse is generated.When the battery cell voltage e _n is higher than the set voltage (Vref), the battery cell voltage The difference between e _n and the set voltage (Vref) [-K (e _n -On the basis of Vref) + 5V], the on duty width of the PWM pulse width is increased.

Also, by using the circuit shown in FIG. 6, the inverting input and the non-inverting input signal of the differential amplifier circuit 51 are designed to be interchanged with each other so that a 5V addition circuit, an inverting adder, or another code conversion circuit can be omitted. The effect can be obtained.

The amplification degree of the differential amplifier circuit 51 can obtain a proper value through an actual test. If the amplification degree is large, even if the voltage of the cell in the DC / DC converter is only slightly high, the current value to be discharged is increased and the control stability is lowered, it is preferable to calculate the amplification degree in consideration of the output current capacity of the DC / DC converter.
In addition, when the DC / DC converter is disposed in each of the battery cells as shown in the embodiment of Figure 4 when the secondary output side of the DC / DC converter is commonly connected to the same DC storage means, the DC / DC converter output side and the DC storage Each resistor is placed between the means and inserted or the line resistance of the connecting line is designed to be larger than a certain value so that the output voltage drop is about 1 to 2% of the output voltage at the maximum current output. In this case, the design and arrangement of the DC / DC converter can prevent the output transformer from saturating the flux even during the continuous conduction mode (CCM) operation of the DC / DC converter. Can be operated and the output voltage control stability can be increased.

The output of the on-duty limiting circuit 54 is connected to the non-inverting input of the comparator 52 through a diode to limit the maximum duty of the PWM pulse width (typically 50% or less in a flyback or forward method), thereby providing DC / DC. The converter can be controlled to convert power uniformly, and when the overcurrent occurs in the DC / DC converter, an overcurrent cut off command 55 signal is input to the input circuit terminal of the PWM drive circuit 56 so that the DC / DC converter can be controlled. I can protect it. The detection of the overcurrent generation can be made by placing a current sensing resistor Rs in the input side circuit of the DC / DC converter. Since such overcurrent detection is generally known, a detailed description thereof will be omitted.

8 is a schematic diagram showing a cell selection control means of a battery equalizing charge device and a PWM control circuit of a controller to be described below in detail. The PWM control of a DC / DC converter employing a commercial control element MB3800 or an equivalent model element is shown in FIG. Specific embodiments of the circuit are shown.

Here, the resistor R2 and the capacitor C3 element determine the operating frequency of the PWM control pulse so that the DC / DC converter is operated in a preferred operating mode as a power supply (SMPS) in flyback or forward switching mode.

In addition, the CTL terminal is a terminal for determining the PWM control mode. When the CTL terminal LOW signal is input, the CTL terminal is operated in stand-by mode. When the HIGH signal is input, the CTL terminal is operated in the operating mode. Is output on pin 5 of the commercial control element MB3800.

 The duty of the PWM control pulse is changed to a desired state by the level control operation of the PWM control signal as described above, which will be described in more detail.

The charging voltage of the battery cell corresponding to the equal charging control object is applied to the inverting terminal and the non-inverting terminal which are input circuits of the differential amplifier circuit U2A. The reference voltage Vref is input to the inverting terminal (pin 2) and the battery cell voltage e _n is input to the non-inverting terminal (pin 3). The signal e _n corresponding to the difference of these signals -Vref is differentially amplified through the differential amplifier circuit U2A and the result is input to the input terminal FB (No. 8 PIN) of the PWM comparator inside the MB3800.

By comparing the sawtooth signal generated by the triangular wave generator or oscillator in the MB3800 with the differential amplifier signal of the differential amplifier circuit U2A in the PWM comparator, a preferable PWM control signal can be obtained.

Since the PWM comparator in the commercial MB3800 has an operating range of about 0.1 to 0.7V, the output signal of the differential amplifier circuit U2A is limited to the diode D1 and divided by the resistors R3 and R4 to output the PWM control signal. By limiting the duty to less than 50%, the flyback or forward switching mode of operation adopted by the DC / DC converter can be desirable.

In addition, as described above, when a voltage signal is detected from the current sensing resistor Rs connected in series with the first switch of the input circuit of the DC / DC converter and a signal corresponding to the overcurrent protection level or more is detected, pin 4 (BR / CTL) is detected. The output current setting and control function is automatically operated through an interface circuit composed of transistors, thereby protecting the DC / DC converter in the event of overcurrent in the DC / DC converter.

In addition, if the VCC voltage is applied (H signal) to the SCP terminal (No. 2 PIN), the overcurrent generation protection or the short circuit protection operation of the DC / DC converter can be prevented from being performed, and the SCP terminal is not connected to the VCC. The short circuit protection function can be activated at. At this time, in order for the PWM control function to automatically return after the short circuit state is released, apply an H or L signal from the outside and change the BR / CTL output mode to Stand-by Mode (terminal open). The state can be canceled, and the BR / CTL output terminal can be grounded to switch to the operating mode, and the short circuit protection operation can be performed again.

In summary, the cell selection control means of the battery cell equalization charging device and the PWM control device of the controller to be described later, that is, the device for controlling the DC / DC converter, consequently, the cell voltage and the set voltage (Vref) of the battery cells constituting the battery tank. Differential amplification means for differentially amplifying the signal, triangular wave / sawtooth wave generation means for generating a triangular wave or sawtooth signal and the output signal of the differential amplification means and the input signal and compares the triangle wave / sawtooth wave signal On Duty (On Duty) And a comparison means for controlling the width, wherein the set voltage may be a first predetermined value or a full charge voltage of the battery cell.

Conventionally, in order to constantly control the output voltage of the DC / DC converter, the output voltage of the DC / DC converter is compared with a reference voltage, which is a control target value (corresponding to the set voltage Vref), and the feedback is fed back. As described above, in the embodiment of the present invention, the duty cycle of the PWM pulse width is compared by comparing the cell voltage e _n with the set voltage Vref without returning the output voltage of the DC / DC converter. Due to the control of the duty width, the control circuit becomes very simple.

At least one of the differential amplifying means, the triangular wave / sawtooth wave generating means and the comparison means may be configured to include a MB3800 commercial element.

An operation of the battery cell equalization charging device described above will be described with reference to FIG. 9. 9 is a flowchart illustrating an operation of a battery cell equalizing charging device according to the present invention.

First, the battery cell voltage constituting the battery tank which is collectively charged (S710) through the cell voltage measuring means is measured.

The measurement result is compared with a predetermined full charge allowable voltage of the battery cell or the average voltage of all battery cells in the battery tank (S 720, 730, 740). In this case, the average voltage may be the average voltage of the remaining battery cells except for the battery cell to be measured, or may be set to the average voltage of all battery cells including the battery cell to be measured.

The battery cell voltage is measured to be higher than the allowable full charge voltage (S 730) and power is supplied from the battery cell to the DC storage means (S 750).

In operation S 760, the battery cell is measured to have a battery cell voltage lower than the average voltage, and the power is supplied from the DC storage means or the rectifying means.

When the state in which the battery cell voltage is equal to the full charge voltage is maintained for a predetermined time, charging is terminated (S 720). When charging is performed for a predetermined battery cell, a full charge voltage is reached after a certain time. The full charge voltage is set according to the characteristics of the battery cell, and voltage charging above the full charge voltage is undesirable but possible. In this embodiment, since the purpose of completing the charging with the full charge power in consideration of the stability of the battery tank and so on is one purpose, continuously monitoring whether the cell power is equal to the full charge power.

In general, when you want to charge the battery tank evenly, it passes the same point as the full charge voltage. It may be necessary to charge to a voltage above the full charge voltage. Therefore, if the charge is stopped immediately because of the same as the full charge voltage, the same problem as in the prior art occurs. Therefore, according to the present embodiment, it is preferable to terminate the charging when the power recovery for the overcharged battery cell or the power supply for the undercharged battery cell is continuously performed and maintained for a predetermined time at the same point as the full charge voltage. The same point as the full charge voltage may be up to ± 1% of the set full charge voltage, and the duration may be variously set according to the type and characteristics of the battery cell.

In addition, when electric power is supplied from the battery cell to the DC storage means, the voltage of the DC storage means and the voltage of the battery tank are compared (S 770), and if the voltage of the DC storage means is higher than the voltage of the battery tank, through the recovery passage means. The power is recovered (S780), otherwise power supply from the battery cell to the direct current storage means is continued.

10 is a schematic view showing another embodiment of a battery cell equal charging device according to the present invention.

The battery cell equalizing charging device shown in FIG. 10 includes cell voltage measuring means 320 for measuring charging voltage of the battery cells constituting the battery tank 310, and cell selection control for selecting an overcharged battery cell according to the measurement result. A means 350, a switching means 370 driven to connect the selected battery cell to the DC / DC converter according to the command of the cell selection control means, and a charging voltage from the connected battery cell according to the driving of the switching means. A DC / DC converter 330 that receives and boosts the voltage, a DC storage means 340 for storing the boosted output voltage of the DC / DC converter, and a recovery passage means 360 for flowing power stored in the DC storage means to the battery tank. ) Is included.

Referring to FIG. 2, the number of DC / DC converters is smaller than the number of battery cells by arranging switching means for connecting the battery cells selected by the cell selection control means for selecting a plurality of battery cells to the DC / DC converter.

Since the number of DC / DC converters can be changed depending on the configuration of the switching means and the number of battery tanks connected in series, the configuration in which one DC / DC converter described herein is arranged is merely one example.

The switching means 370 is an element which connects the battery cells overcharged by the cell selection control means to the DC / DC converter, and is connected to the input / output terminals of each of the battery cells and is turned on or off by the command of the cell selection control means. It includes a switch. The command of the cell selection control means is made based on the cell voltage measured by the cell voltage measuring means. The configuration of the switching means can be implemented in various shapes combining one or more switches.

The DC / DC converter 330 recovers surplus power from the overcharged battery cell, boosts it properly, and transfers the power to the DC storage means.

The DC / DC converter may be one of a flyback, forward, step-down buck, step-up boost, and step-down / step-up buck-boost schemes.

In addition, the DC / DC converter is a transformer T4n disposed between the switching means 370 and the direct current storage means 340 to which a plurality of battery cells are connected, as shown in FIG. 11. And a diode D1 facing the anode of the direct current storage means and connected in series with the transformer and the direct current storage means. At this time, the transformer T4n is wound so that the surplus power of the battery cell can be boosted and supplied to the DC storage means, and the winding ratio may be set in consideration of the charge voltage of the battery tank and the full charge voltage of each battery cell.

In the battery cell equalizing charging device shown in FIG. 11, the switches Sp41 to Sp4n are disposed for each battery cell to form the switching means 370. The switches Sp41 to Sp4n are commonly connected to the winding terminal of a transformer (high frequency transformer, T _4n ) and are designed to act as a DC / DC converter by PWM control operation of each switch of each battery cell. The winding terminal of transformer T _4n is electrically blocked from each other by diodes D _{4 (1)} to D _{4 (n-1) and} D _4n connected to the negative terminal side of each battery cell, respectively _, and PWM control operation of each switch is performed. A time reflux passage is formed.

According to the above structure, the structure of a cell selection means and a direction selection means becomes very simple. However, in this configuration, it is possible to recover the charging power of the required battery cell, but cannot supply the charging power.

In addition, it is necessary to design such that any one of the switches Sp41 to Sp4n is controlled by the cell selection control means so that other switches cannot be operated during operation.

Also, in consideration of the energy-saving effect of the price, the designer decides to replace the boost converter circuit consisting of a DC / DC converter circuit and a DC storage device with a series resistor in order to be suitable for a small capacity battery by discharging the voltage of the overcharged unit cell. The manufacturing cost can be reduced by bypassing or bypassing.

Referring to the battery cell equalizing charge device of FIG. 11 in more detail. That is, the battery cell equalizing charging device according to the present embodiment includes cell voltage measuring means for measuring the charging voltage of each battery cell, cell selection control means for selecting an overcharged battery cell according to the measurement result, and each of the battery cells. A plurality of switches (Sp41 to Sp4n) connected in series, a transformer T _4n connected to one end of the primary side in common with the opposite ends of the switches connected to the battery cells, respectively, and the cathodes of the respective battery cells are respectively directed; A plurality of diodes (D4 ₍₁₎ to D4 _{(n-1), D4n} ) connected to the cathode and the other end of the transformer to provide a reflux passage during step-up conversion _, selected by the cell selection control means and PWM through the switch and the transformer are controlled stored in the direct current storage means C _0, and the direct current storage means for storing the step-up converting output power of the battery power recovery to flow twos It can include a passage means (360).

11 illustrates the diodes connected in anti-parallel to the plurality of switches Sp41 to Sp4n, but in the case of employing an IGBT or FET device in which the diodes are built in anti-parallel in parallel, the plurality of switches may be A first switch connected in series with the transformer and the battery cell and a first diode directed in series with the first switch, the first switch being connected in series with the transformer and the direct current storage means. And a second diode D1 directed toward the direct current storage means.

Based on the technical solutions as described above, the overcharged battery cell is selected by the cell selection control means and the charge voltage of the battery cell overcharged by the DC / DC converter is boosted to store the direct current. Can be stored on the device. Power stored in the direct current storage device is supplied to the battery tank 310 via the recovery passage means 360.

Meanwhile, the DC / DC converter may include a first switch for receiving a charging voltage from an overcharged battery cell and boosting it. PWM control may be performed through the first switch by including a first switch that drives a DC / DC converter separately from the switching means. Of course, it is also possible to PWM control each switch of the switching means shown in accordance with the embodiment of FIG. Each switch of the switching means is preferably driven by the command of the cell selection control means, but as in another embodiment, the first switch included in the DC / DC converter may be driven through a separate control unit. Of course, the control unit and the cell selection control means may be integrally formed.

In the above, the method of recovering the charging voltage, that is, surplus power from the overcharged battery cell to the direct current storage means through the recovery passage means and supplying it to the battery tank, the supply of power stored in the direct current storage means to the insufficiently charged battery cells It is possible.

To this end, the cell selection control means should be able to select an overcharged or undercharged battery cell according to the measurement result. In addition, the DC / DC converter may store the power stored in the DC storage means when the selected battery cell is a battery cell that is insufficiently charged as well as a first switch for receiving and charging a charging voltage from the overcharged battery cell when the selected battery cell is an overcharged battery cell. A second switch for stepping down and supplying to the undercharged battery cell should also be included.

This configuration will be described with reference to FIGS. 12 and 13.

12 is a schematic view showing another embodiment of a battery cell equal charging device according to the present invention in detail.

The battery cell equalizing charging device illustrated in FIG. 12 includes a battery tank 310, a cell voltage measuring unit 320, a cell selection control unit 350, a control unit 380, a switching unit 470, and a DC / DC converter 430. ) And direct current storage means (340).

Battery tank 310 is composed of a total of n battery cells E1 ~ En, the switching means 470 is composed of a plurality of switches SW1 ~ SWm to select each of the battery cells. In order to select one battery cell, two switches are connected to both the positive and negative ends of the battery cell. Therefore, a switch connected to the negative electrode of the front battery cell and a switch connected to the positive electrode of the rear battery cell are disposed between each battery cell, and the switch connected to the battery cell negative electrode is connected to the negative electrode of the DC / DC converter and is connected to the battery cell positive electrode. The switch connected to is connected to the positive pole of the DC / DC converter. Since only a switch connected to the positive electrode of En exists at the upper end of the battery cell En, and only a switch connected to the negative electrode of E1 exists at the lower end of the battery cell E1, the number of switches provided in the switching means is (2 * n). Of course, this switch configuration can be changed in various ways. The point is to select each battery cell and connect them to the positive and negative poles of the DC / DC converter.

For example, to select battery cell En-1, the switches SWm-2 and SWm-3 must be turned on. In this way the switching means selects one battery cell. The battery cell selected by the switching means is an overcharged or undercharged battery cell and is determined by the cell selection control means. There may be a plurality of overcharged or undercharged battery cells at the same time, and the overcharged and undercharged battery cells may be mixed. In this case, the switching means may select the battery cells in the order of the difference from the full charge voltage and the difference from the average voltage according to the control of the cell selection control means. In addition, all overcharged battery cells or all undercharged cells may be selected. For this purpose, protection of a DC / DC converter and protection of a DC storage means should be considered.

The DC / DC converter 430 includes a transformer T disposed between the switching means 470 and a direct current storage means 340 such as a capacitor Co, a first switch Sp connected in series with the transformer T and the switching means, and a transformer T; A second diode D2 connected in series to the direct current storage means 340 and directed to the direct current storage means, and additionally directed to the first diode D1 and the second diode D2 directed to the switching means and connected in parallel to the first switch Sp. It may further include a second switch Ss connected in parallel and driven opposite to the first switch Sp.

In some cases, it may further include a resistor Rs connected in series with the switching means and the transformer T for voltage regulation.

Here, the first switch Sp and the second switch Ss are driven by the control of the control unit 380 and are driven opposite to each other.

In the state where the first switch Sp is driven and the second switch Ss is turned off, the charging voltage is boosted by the transformer T from the overcharged battery cell via the first switch Sp and stored in the DC storage means Co via the second diode D2. That is, excess power is recovered from the overcharged battery cell. Of course, at this time, the overcharged battery cell will be a battery cell in which the cell voltage measured by the cell voltage measuring means exceeds the full charge voltage. Such determination is a control unit that receives the cell voltage of each battery cell from the cell voltage measuring means. Is done by. On the other hand, the cell selection control means instructs the switching means to select the overcharged battery cell and connects the overcharged battery cell to the DC / DC converter. The surplus charging power stored in the direct current storage means is recovered back to the battery tank through the recovery passage means.

On the contrary, in the state in which the first switch Sp is turned off and the second switch Ss is driven, the power stored in the DC storage means Co or the power of the rectifying means is stepped down in the transformer T through the second switch Ss and shortened through the first diode D1. It is supplied to a charged battery cell. That is, power is supplied to the undercharged battery cell. In this case, the undercharged battery cell will be a battery cell in which the cell voltage measured by the cell voltage measuring means is less than the average voltage. Such determination is also made by the controller. At this time, instructing the switching means to connect the undercharged battery cell to the DC / DC converter becomes the cell selection control means. The cell selection control means should be able to further select an undercharged battery cell in addition to the overcharged battery cell for controlling the second switch.

For reference, the control unit may include a function of controlling pulse width modulation (PWM) of at least one of the first and second switches of the DC / DC converter to recover the excess power and to supply the amount of power supplied to the undercharged battery cell. Will be adjusted.

13 is a schematic view showing another embodiment of a battery cell equalizing charge device according to the present invention in detail.

The DC / DC converter 530 shown in FIG. 13 is arranged in parallel between the inductor L, the inductor L, and the direct current storage means 340 disposed in series between the switching means 470 and the direct current storage means 340. And a second diode D2 directed toward the anode of the first switch Sp disposed and the direct current storage means Co and connected in series with the inductor and the direct current storage means between the first switch and the direct current storage means Co. Additionally, the method may further include a first diode D1 directed toward the anode of the battery cell and connected in parallel to the first switch Sp, and a second switch Ss driven opposite to the first switch Sp and connected in parallel with the first diode D1. .

When the PWM control pulse is applied to the first switch Sp, the energy stored in the inductor L through the overcharged battery cell is released through the second diode D2, boosted and rectified to charge the DC storage means Co. In addition, when the PWM control pulse is applied to the second switch Ss, additional charging power is generated from the DC storage means Co or the rectifying means through the second switch Ss and the inductor L, and undercharged by free wheeling by the first diode D1. The battery cell will be charged.

Components other than the DC / DC converter are the same as those in FIG. 12, and thus description thereof is omitted.

Hereinafter, the battery cell equal charging device will be described in another perspective.

One embodiment of a battery cell equalizing charging device and a method of controlling the same to measure the voltage of each battery cell to equalize and charge the voltage of each battery cell when the voltage is higher than the voltage of other battery cells or higher than the maximum charge allowable voltage. Give an example.

As an embodiment of the present invention for achieving the above object, in a battery tank in which a plurality of battery cells are connected in series, boosting the surplus power of the charge of the battery cells to charge the DC storage means such as a capacitor connected to the secondary side A DC / DC converter; Cell connecting means (SWn to SW ₁ ) (switching means) for allowing the DC / DC converter to be connected corresponding to each cell; And PWM control means (control unit) for selectively controlling the DC / DC converter to PWM control the DC / DC converter according to the level of the voltage detection value of the cell.

In addition, the DC / DC converter, it is preferable to further include a switch for operating in both directions to convert the amount of storage power of the DC storage means such as a capacitor connected to the secondary side to charge the insufficiently charged cells. In addition, by configuring in this way it is possible to maximize the industrial use effect of the present invention.

In another embodiment of the present invention for achieving the above object, in charging a battery system in which a plurality of cells are connected in series, each battery cell is provided for each battery cell connected to the secondary side of the surplus charging electricity of each battery cell A DC / DC converter bypassing a direct current storage means such as a capacitor and replenishing a cell in which the direct current storage means is temporarily charged or undercharged using power stored in a secondary capacitor by the bypassed amount of electricity; And respective PWM control means for sensing the terminal voltage of the cell and selectively controlling each DC / DC converter according to its detection level to PWM control the DC / DC converter.

The direct current storage means includes a device or device capable of storing direct current power, such as a DC electrolytic capacitor or a supercapacitor.

Each of the PWM control means may be synchronized with each other or independently controlled as necessary.

In addition, when the DC storage means such as a capacitor commonly connected to the secondary side of the DC / DC converter is charged with the surplus electricity temporarily when the terminal voltage of the DC storage means rises above a certain level to be recovered to the battery or charging device side It is preferable to further include a recovery passage means composed of a diode and the like.

The DC / DC converter may be an isolated converter including a transformer, such as a conventional flyback or forward converter, a step down buck, a step up boost, a step down / step up buck- Transformerless, non-isolated converters can be employed, such as boost-boost converters.

In addition, the function of the PWM control means may further include a cell management function (BMS) that measures the state of charge of each battery cell to protect the battery cell from a risk factor.

 In the control method for PWM control of each DC / DC converter, the DC / DC converter operates to bypass the charging current when the charging voltage of the battery cell to be controlled is higher than the first predetermined value of the battery cell. Preferably, the control pulse is controlled to be applied to the switch to be controlled, and the control pulse is proportionally PWM controlled by the difference between the first predetermined value and the current charging voltage of the cell.

The first predetermined value is preferably set to be equal to the maximum allowable value of the full charge voltage of the cell.

In addition, in the control method for PWM control of each DC / DC converter, when the charge voltage of the battery cell to be controlled is lower than the second predetermined value, the DC / DC converter adds a supplementary current to the battery cell to be controlled in the undercharge state. The control pulse is controlled to be applied to a switch corresponding thereto, and the control pulse is PWM controlled to generate a set charging current until the charging voltage of the cell to be controlled reaches a third predetermined value.

The second predetermined value is generally selected to be equal to the average charging voltage of the other battery cells, and the third predetermined value is preferably set to be equal to the limit value of the full charge voltage of the corresponding battery cell.

15 is a block diagram showing the configuration of a preferred embodiment of the present invention.

Referring to FIG. 15, a DC / DC converter 21 according to a preferred embodiment of the present invention may include a first switch Sp of a flyback or forward switching mode power supply (SMPS) between positive and negative terminals of a battery cell. The primary windings of the transformer T are connected in series. A capacitor Co, which is a direct current storage means, is connected to the output of the switching mode power supply SMPS.

When the charge voltage of the control target cell connected to the DC / DC converter 21 is higher than the allowable full charge voltage, a PWM control pulse is applied to the first switch Sp of the DC / DC converter 21 to charge the corresponding cell. The current is bypassed through the first switch Sp and the transformer T, and rectified by the secondary winding of the transformer T and the second diode D2 to charge the output capacitor Co, which is a direct current storage means.

In addition, both ends of the capacitor Cn are connected to the battery string through the anode side diode 23 and the cathode side diode 22 so that the system voltage of the battery string can be broken. Therefore, when the charging voltage of the capacitor Co is higher than the battery string, the capacitor Co is discharged to the battery string side.

In addition, in FIG. 15, even if the connection positions of the first switch Sp and the transformer T are interchanged, the same technical effect may be obtained.

Cell connecting means (SWn ~ SW ₁ ) is such that the DC / DC converter 21 is connected to the battery cell of the control target that needs equal charging, respectively, and by this connection structure one DC / DC converter (21) This makes it possible to charge many series-connected battery cells evenly. The cell connection means SWn to SW ₁ are designed to generate a cell selection signal (generated by the control means) by the BMS since the cell voltage can be found by measuring a cell voltage in a battery management system (BMS). This is preferred.

In particular, in the large-capacity battery system, the capacity of the DC / DC converter 21 is also greatly required, so that only the cell connection means (SWn ~ SW ₁ ) can be charged evenly by each DC / DC converter by one DC / DC converter There is this.

On the other hand, the PWM control pulse is a flyback or forward switching mode power supply (SMPS) can be controlled in a constant current control mode when the battery cell is higher than the full charge voltage tolerance, the input current or output current (SMPS) is detected, It is preferable to generate the PWM control pulse by the operation mode as shown.

On the other hand, according to another embodiment of the present invention, if the second switch (Ss) in parallel with the second diode (D2) for the purpose of evenly charging the battery cell is insufficiently charged in Figure 15 of the transformer (T) It may be operated as a bidirectional DC / DC converter capable of supplying additional charging current through the secondary side, and the transformer T may step down the output voltage because the secondary winding is high.

The DC / DC converter 21 applies a PWM control pulse to the second switch Ss when the charging voltage of the control target battery cell (required battery cell) is lower than the average of the charging voltages of the other battery cells, thereby outputting the output capacitor (Co). The charging current for recharging the battery cell from the amount of electricity accumulated in the battery is generated through the secondary side of the second switch Ss and the transformer T and rectified by the first diode D1 to charge the battery cell to be controlled. It becomes possible. Thereafter, the PWM control pulse is preferably controlled to generate a charging current until the charging voltage of the cell reaches an average value.

In addition, the PWM control pulse may be controlled in the constant current control mode of the flyback or forward switching mode power supply (SMPS) when the undercharged battery cell is lower than the average of the charging voltage of the other battery cells, as shown in FIG. By the operation mode as described above, it is preferable to control the PWM proportionally according to the difference between the average charging voltage of the other battery cells and the current charging voltage of the control target cell.

FIG. 16 illustrates an embodiment in which the flyback or forward switching mode power supply (SMPS) is configured as another type of bidirectionally operated boost converter.

The role of the first switch, the second diode, the second switch, or the first diode in the circuit operation mode of the bidirectional actuated boost converter 31 is the operation of the flyback or forward switching mode power supply (SMPS) shown in FIG. 3. The mode and its role are almost similar.

That is, the PWM control pulse is applied to the first switch Sp so that the energy stored in the inductor L is boosted and rectified while being discharged through the second diode D2 to charge the capacitor Co. In addition, when the charging voltage of the control target cell is lower than the average of the charging voltages of the other cells, a PWM control pulse is applied to the second switch Ss so that an additional charging current is generated from the capacitor Co, which is a DC storage means, with the second switch Ss. The battery cell generated through the inductor L and freewheeling by the first diode D1 may be charged.

The boost converter does not require a transformer (T) as compared to the flyback or forward switching mode power supply (SMPS) of FIG. 15, but the circuit can be simplified. Since it is not larger than 4 times, it is possible to select and design a suitable circuit according to the designer's judgment in consideration of the characteristics of the battery system.

In addition, when the current capacity Ah of the battery cell is large and the charge / discharge current of the target control cell is largely required during the cell equalization charging operation, the flyback or forward switching mode power supply (SMPS) of FIG. 15 may be used. The DC / DC converter 141 may be replaced with an inverter circuit structure that can operate in both directions even if the circuit configuration is complicated. Specific configurations and operation control modes of the inverter-type circuit are already known and thus may be referred to.

In order to enhance the industrial use effect, a converter capable of charging / discharging (charging and retrieval) control is preferably used. However, for supplementary charging purposes, a converter that receives AC power from the outside and converts it into DC is used. The rectifying means 190 may be employed, and the present invention is not limited thereto, and various types of DC power supplies may be used.

Meanwhile, FIG. 4 or FIG. 15 is an embodiment of the present invention employing the DC / DC converter 21 of the insulated transformer, which may be advantageously applied to a relatively small battery system.

Each of the battery cells constituting the battery system (stack) may be configured such that the respective primary-side circuits are connected in series by installing the DC / DC converters 21 illustrated in FIG. 15. The outputs of the DC / DC converters 130 are electrically connected to the battery tanks (strings) by the transformers Tn to T _{1 while} being commonly connected to the output capacitors Co having a relatively large capacity.

The positive and negative terminals of the output capacitor (Co) are connected to the battery through the positive diode (connected to the battery tank anode) and the negative diode (connected to the battery tank cathode) of the circuit passage means 160 so that the voltage of the battery string (stack) is broken. It is connected to a string. Therefore, when the charging voltage of the capacitor Co is higher than the battery string, the capacitor is discharged to the battery string side, thereby limiting the increase of the voltage of the capacitor Co, which is a direct current storage means.

In addition, in the illustrated embodiment, even if the connection positions of the first switch Sp and the transformer T are interchanged, the same technical effect may be obtained.

FIG. 16 illustrates a DC / DC converter 230 for each battery cell, and the DC / DC converter 230 includes a bidirectional operation boost converter. The bidirectionally operated boost converter is connected to each battery cell in a series structure similarly to FIG. 15. Each output terminal is commonly connected to a relatively large output capacitor (Co), and a battery string (stack) and each negative terminal (the-terminal of the first switch Sp) of the bidirectionally operated boost converter are connected to the output capacitor. Diodes (D3 ₁ ) respectively connected to the cathode side of (Co) D3 _n ) is electrically blocked from each other.

The bidirectional boost converter does not have a transformer T unlike the DC / DC converter 21 in the form of a flyback or forward switching mode power supply (SMPS) shown in FIG. 15. The power (energy) stored in the inductor is a blocking diode D _{3 (n)} , the negative terminal of the nth battery cell, the positive terminal of the battery cell, the inductor Ln, the second diode D2n, and the output capacitor Co. Since the blocking diode D _{3 (n)} continues to conduct in the operation mode stepped up through), the negative terminal of the nth battery cell has the same potential as the negative terminal of the output capacitor Co. Therefore, in the inductor energy emission operation section of the nth boost converter, it is necessary to control the other boost converters to be synchronized with each other so as not to operate in such an operation mode.

Next, a control operation process of the battery cell equalizing charging (balancing) device according to an exemplary embodiment of the present invention will be described.

First, the charging voltage of each battery cell is sensed to determine and select a cell to be controlled (prevented) from overcharging (a cell higher than the charge allowable voltage or a cell charged higher than the average voltage of each battery cell).

The PWM control means of the DC / DC converter corresponding to the control target cell is operated to apply a PWM control pulse to the first switch Sp.

In the case where only one DC / DC converter is provided, such as in the case of a battery system having a relatively large capacity, the step of allowing the control target cell to be connected to the cell connecting means may be further required.

 Each DC / DC converter 21 or 31 is PWM controlled in a boost mode according to the PWM control signal of the first switch Sp.

The amount of conversion power obtained from the charging voltage of the control target cell is rectified by the second diode D2 to charge the DC storage means such as the output capacitor Co.

Then, when the voltage charged in the DC storage means such as the output capacitor (Co) rises above a certain level, the power is recovered to the battery string or the charging device through a recovery passage means composed of a diode or the like.

On the other hand, the control voltage is found to be lower than the average charging voltage of the other cells.

In the DC / DC converter, a PWM control pulse is applied to the second switch Ss to operate in the step-down mode with the capacitor Co as an input.

At this time, the power energy of the input capacitor Co or the stop value is converted and rectified or refluxed through the first diode D1 to charge the control target cell.

Prior to this, in the case of converting power by using the DC / DC converter in common, such as in a case of a relatively large capacity battery system, it is further necessary to have a control cell connected through a switching means.

The PWM control pulse is controlled to generate a charging current until the charging voltage of the cell reaches an average value. Here, the PWM control pulse of the DC / DC converter is preferably PWM controlled proportionally by the difference between the average of the charging voltage of the other cells and the current charging voltage of the cell.

When the cell voltage detection value of the control target reaches a set value and becomes full, the PWM control means selectively turns off the corresponding DC / DC converter to stop charging of the cell to be controlled.

According to the present invention, in the case of adopting a charging method in which a plurality of cells are collectively charged, each cell voltage is measured in the charging process, and when the cell voltage is higher than the voltage of another cell or higher than the maximum allowable voltage, When the connected DC / DC converter is operated to discharge (recover) the charging current to the output side to maintain a constant charging voltage, or to undercharge the specific battery cell to increase the industrial effect, the DC / DC The converter operates in the reverse direction to recharge the undercharged cells, thereby preventing overcharging, overdischarging and undercharging, thereby preventing damage or explosion of the battery, which may occur, and the life of the battery system (stack). Can be extended.

Those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. Therefore, the above-described embodiments are to be understood as illustrative in all respects and not as restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

Applicable to various rechargeable batteries.

In particular, according to the present invention, since each cell has an equal charging effect in which each cell is individually charged at the end of the charging under any charging and discharging conditions of a battery system connected in series, the battery is charged in an equal condition without occurrence of overcharge or low charging phenomenon. This is possible.

Therefore, it is applicable to stacks connected in series of lithium ion batteries and has many advantages of high electrical integration of lithium ion batteries. Thus, the battery system or electric vehicle for emergency large capacity can be utilized and spread by utilizing the technology of the present invention.

1 is a block diagram showing the configuration of a battery charging apparatus according to the prior art.

2 is a schematic view showing a battery cell equalizing charge device according to the present invention.

3 is a schematic diagram showing a state in which a cell voltage measuring means and a cell selection control means are added to a battery cell equalizing charging device according to the present invention.

Figure 4 is a schematic view showing a battery cell equalizing charge device according to the present invention including one embodiment of a DC / DC converter.

5 is a schematic diagram showing another example of a DC / DC converter showing a battery cell equalizing charging device according to the present invention.

6 is a schematic diagram showing a control circuit PWM control circuit of the battery cell equalizing charge device according to the present invention.

FIG. 7 is a schematic diagram illustrating a PWM waveform output by the configuration of FIG. 6. FIG.

FIG. 8 is a circuit diagram specifically illustrating a PWM generation control circuit employing a commercially available element as an embodiment of the present invention. FIG.

9 is a flowchart showing the operation of the battery cell equalizing charging device according to the present invention.

10 is a schematic view showing another embodiment of a battery cell equalizing charge device according to the present invention.

Figure 11 is a circuit diagram showing another embodiment of a battery cell equalizing charge device according to the present invention.

12 is a schematic diagram showing another embodiment using an isolated converter according to the present invention in detail.

Figure 13 is a schematic diagram showing another embodiment using a non-isolated converter according to the present invention in detail.

14 is a circuit diagram showing a battery cell equalizing charge device according to another embodiment of the present invention.

15 is a block diagram of an isolated converter of a battery cell equal charging device according to a preferred embodiment of the present invention.

16 is a block diagram of a non-isolated converter according to another preferred embodiment of the present invention.

Description of the Related Art

110, 310 ... battery tank 120, 320 ... cell voltage measuring means

130, 230, 330, 430, 530 ... DC / DC converters

150, 350 ... cell selection control means 140, 340 ... direct current storage means

160, 360 ... recovery passage means 370, 470 ... switching means

380 ... control section 190, 390 ... rectification means

Claims (23)

In the battery equalization charging device for equally charging each of the battery cells of the battery tank in which a plurality of battery cells are connected in series with each other, A DC / DC converter disposed in each of the battery cells, each having a capacitor in an internal output circuit, and independently controlled by a generated PWM signal; DC storage means commonly connected to the outside of the output terminal of the DC / DC converter, the DC storage means for supplying power to store the step-up converted power of the DC / DC converter or to transfer the temporarily stored energy to the under-charged battery cell; And When the voltage of the DC storage means rises, an electricity supply line is provided so that the stored power flows to the battery tank or part of a series connection terminal (string) side of the battery tank, and the output side of the DC / DC converter is connected to the battery tank or the battery tank. A return passage means for blocking from some series-connected ends (strings), The pulse width modulation (PWM) signal is characterized in that the on duty width of the PWM pulse is controlled by a differential amplification signal between the control battery cell voltage and the set voltage (Vref). Battery cell evenly charging device. The method of claim 1, And said direct current storage means comprises at least one of a DC electrolytic capacitor or a supercapacitor, and a DC electrolytic capacitor designed on an output side in said DC / DC converter. The method of claim 1, Cell voltage measuring means for measuring a charging voltage of the battery cell; And cell selection control means for selecting an overcharged or undercharged battery cell according to the measurement result. And said DC / DC converter is driven by a command of said cell selection control means. 4. The method according to any one of claims 1 to 3, The DC / DC converter, A transformer disposed between the battery cell and the direct current storage means; A first switch connected in series between the transformer and the battery cell; And A second diode directed towards said direct current storage means and connected in series with said transformer and said direct current storage means; Battery cell equalization charging device comprising a. The method of claim 4, wherein The DC / DC converter, A first diode directed at the anode of the battery cell and connected in parallel to the first switch; And A second switch connected to the second diode in parallel and driven opposite to the first switch; A battery cell equalizing charging device for stepping down at least one of the power stored in the DC storage means or the power of the rectifying means for supplying power to the battery tank by driving the second switch to supply a charging current to the undercharged battery cell. . delete 4. The method according to any one of claims 1 to 3, The DC / DC converter, An inductor connected in series with the positive electrode of the battery cell and the direct current storage means; A first switch disposed in parallel to the direct current storage means between the inductor and the direct current storage means; And A second diode directed between said first switch and said direct current storage means and directed in series with said inductor and said direct current storage means; Battery cell equalization charging device comprising a. The method of claim 7, wherein A first diode directed at the anode of the battery cell and connected in parallel to the first switch; And A second switch connected in parallel with the second diode and driven opposite to the first switch; A battery cell equalizing charging device for stepping down at least one of the power stored in the DC storage means or the power of the rectifying means for supplying power to the battery tank by driving the second switch to supply a charging current to the undercharged battery cell. . 4. The method according to any one of claims 1 to 3, The recovery passage means, The battery cell equalizing charging device is connected to the positive and negative terminals of the battery tank or rectifying means, the plurality of battery cells are charged or connected to some series connection terminal (string) of the battery tank. delete delete delete delete delete delete In the battery cell equalizing charging device for equally charging each of the battery cells of the battery tank in which a plurality of battery cells are connected in series with each other, Cell voltage measuring means for measuring a charging voltage of each battery cell; Cell selection control means for selecting an overcharged battery cell according to the measurement result; Switching means for PWM driving in accordance with a selection command signal of said cell selection control means; A transformer disposed in common with each of the battery cells and the switching means; A direct current storage means connected to an outer side of a secondary output terminal of the transformer and supplying power to store boost-converted power of the transformer or to transfer temporarily stored energy to an undercharged battery cell; And When the voltage of the DC storage means rises, an electricity supply line is provided so that the stored power flows to the battery tank or a part of a series connection terminal (string) side of the battery tank, and the secondary output side of the transformer is connected to the battery tank or the partial series connection. A recovery passage means for blocking from a stage (string), The PWM (Pulse Width Modulation) signal is, A battery cell equalizing charge device, characterized in that the on duty width of a PWM pulse is controlled by a differential amplification signal between a control target battery cell voltage and a set voltage (Vref). The method of claim 16, The switching means, A plurality of switches commonly connected to each of the battery cell cathodes and one end of the transformer primary side and PWM driven by a command of the cell selection control means; And And a plurality of diodes respectively directed to the transformer and electrically connected to each of the battery cell anodes and the other end of the transformer primary side to electrically block each other and provide a reflux passage. The method according to claim 1 or 16, In order to control the PWM, Differential amplifying means for differentially amplifying the difference between the cell voltage and the set voltage Vref of the battery cells constituting the battery tank; Triangular / sawtooth generating means for generating a triangular or sawtooth wave signal; And Comparison means for proportionally controlling the on duty width of the PWM pulse width by receiving and comparing the output signal of the differential amplifying means and the triangle / sawtooth signal; Battery cell equalization charging device comprising a. The method of claim 18, The set voltage (Vref), The battery cell equalizing charge device, characterized in that any one selected from the full charge allowable voltage of the battery cell, the average value of the charge voltage of the battery cells and the divided voltage of the battery cells. The method of claim 18, And at least one of the differential amplifying means, the triangular wave / sawtooth generating means, and the comparing means comprises a MB3800 commercial element. delete delete The method of claim 1, The DC / DC converter, Isolated converters with transformers, such as conventional flyback, forward converters or step-down bucks, step-up boosts, step-down / step-up buck-boost converters Battery cell equal charging device including any one of the non-isolated converter, such as.

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