TWI491141B - System and method for charging battery - Google Patents

Description

Battery charging system and method

The present invention relates to a battery charging system and method, and more particularly to a charging system and method for a battery that can achieve high charging efficiency by switching two charging devices.

Today's portable electronic products are becoming more and more complex, and built-in processors usually have powerful computing power, so they consume a lot of power. Since portable electronic products use batteries as power sources; with the rapid development of portable electronic products, the use of various batteries has increased, and many new rechargeable batteries have been developed, such as nickel-cadmium batteries and nickel-hydrogen batteries. Battery, lithium ion (Li-ion) battery and lithium polymer (Li-ion polymer) battery.

For example, lithium batteries are currently the most widely used rechargeable batteries, which can be made into prismatic or rectangular, cylindrical, and button-type according to the requirements of different electronic products. ), you can use a single battery for low-power applications, or you can combine multiple cells in series and parallel to get higher voltage and capacity for power tools and notebook computers. In addition, lithium-ion batteries have small size and no memory. Effects, low self-discharge, high stability, fast charging, etc., become the best choice for power supply in light and short portable electronic products or electric vehicle applications requiring high endurance.

When the internal storage of the lithium battery is exhausted and the battery needs to be recharged, the constant-current/constant-voltage (CC/CV) mode is the most common charging method for the lithium battery. Moreover, in response to the international trend of energy saving and carbon reduction, conversion efficiency has become an important consideration in charger design practice. The switching-mode power converter charging architecture used in the charging system of the conventional lithium battery has better conversion efficiency when operating in the constant current charging mode, but when the switching power converter is charged at a constant voltage The mode operation is in the light load range, and the light load operation of the switching power converter causes an increase in the switching power loss due to the high frequency switching, thereby reducing the conversion efficiency.

Therefore, it is necessary to provide a battery charging system and method to solve the problems of the conventional technology.

The main object of the present invention is to provide a battery charging system and method, which adopts a reconfigurable charging architecture, and uses different charging structures to charge the battery in a constant current and a constant voltage mode, so as to effectively improve conversion efficiency. Moreover, since the conversion efficiency is increased, and the process of converting the power output from the power supply to the energy stored in the battery is improved, the advantage of reducing the charging time can also be obtained.

A secondary object of the present invention is to provide a battery charging system and method using a reconfigurable charging architecture to charge a battery in different current and constant voltage modes using different charging architectures to increase conversion efficiency. Moreover, since the conversion efficiency is increased to equivalently reduce the waste heat caused by the power loss, the problems caused by overheating in the charging process of the portable device can be alleviated, and the reliability of the internal electronic components in the charging process is increased, and the battery safety is improved. Sex.

To achieve the above objective, the present invention provides a battery charging system for causing a power source to output a power signal to a battery, the charging system comprising: at least two sensors, a switchable charger, and a core controller . The two sensors are respectively coupled to the battery to sense at least two feedback signals of the battery. The switchable charger includes a first charger and a second charger. The first charger is configured to provide a first charging signal to the battery in a first charging mode. The second charger is connected in parallel to the first charger in a second charging mode for providing a second charging signal to the battery. The core controller controls the switchable charger to switch to the first or second charging mode according to the two feedback signals.

In one embodiment of the invention, the battery is one of a nickel cadmium battery, a nickel hydrogen battery, a lithium ion battery, and a lithium polymer battery.

In an embodiment of the invention, the two sensors are a current sensor and a voltage sensor, respectively.

In an embodiment of the invention, the charging system further includes a feedback network through which the two sensors feed back the two feedback signals to the core controller.

In an embodiment of the invention, the first charging mode is a constant current charging mode formula.

In an embodiment of the invention, the second charging mode is a constant voltage charging mode.

In an embodiment of the invention, the first charger is a switched power converter.

In an embodiment of the invention, the second charger is a low dropout linear power converter.

In an embodiment of the invention, the switchable charger further includes a switch, and the core controller switches the switch according to the two feedback signals.

An embodiment of the present invention provides a method for charging a battery, comprising the steps of: (a) providing a battery charging system for causing a power source to output a power signal to a battery, the charging system comprising: at least two sensors a switchable charger and a core controller; (b) measuring the voltage signal and the current signal of the battery by using the two sensors; (c) returning the voltage signal and the current signal of the battery to the core controller Determining to switch the battery to a first charging mode or a second charging mode; (d) switching the switchable charger by the core controller to select to provide a first charging signal or a second charging signal to the battery And (e) completing the charging process and stopping outputting the power signal.

In an embodiment of the invention, the first charging mode is a constant current charging mode, and the second charging mode is a certain voltage charging mode.

10‧‧‧Battery

20‧‧‧Power supply

30‧‧‧Charging system

31‧‧‧ Sensor

311‧‧‧ Current Sensor

312‧‧‧Voltage sensor

32‧‧‧Switchable charger

321‧‧‧First Charger

322‧‧‧Second charger

33‧‧‧ core controller

34‧‧‧Responsible network

S1, S2‧‧‧ switch

S01, S02, S03, S04, S05‧‧ steps

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram showing the core circuit of a charging system for a battery according to a preferred embodiment of the present invention.

Fig. 2 is a graph showing charging voltage and charging current variation characteristics of a charging system of a battery according to a preferred embodiment of the present invention.

Figure 3 is a flow chart showing a method of charging a battery according to a preferred embodiment of the present invention.

The above and other objects, features and advantages of the present invention will become more <RTIgt; Furthermore, the directional terms mentioned in the present invention, such as up, down, top, bottom, front, back, left, right, Inner, outer, side, surrounding, central, horizontal, lateral, vertical, longitudinal, axial, radial, uppermost or lowermost, etc., only refer to the direction of the additional schema. Therefore, the directional terminology used is for the purpose of illustration and understanding of the invention.

Please refer to FIG. 1, which discloses a battery 10 of a preferred embodiment of the present invention. A core circuit block diagram of the charging system 30 for causing a power source 20 to output a power signal to a battery 10. The charging system 30 mainly includes at least two sensors 31, a switchable charger 32, and a core controller. 33. The two sensors 31 are respectively coupled to the battery 10 to sense at least two feedback signals of the battery 10 . The switchable charger 32 includes a first charger 321 and a second charger 322. The first charger 321 is configured to provide a first charging signal to the battery 10 in a first charging mode. The second charger 322 is connected in parallel to the first charger 321 in a second charging mode for providing a second charging signal to the battery 10. The core controller 33 controls the switchable charger 32 to switch to the first or second charging mode according to the two feedback signals.

In this embodiment, the battery 10 is a rechargeable battery such as nickel cadmium. One of a battery, a nickel-hydrogen battery, a lithium ion battery, and a lithium polymer battery. Taking a lithium battery as an example, the electrolyte in the battery 10 may be a pseudocolloid, a polymer (such as a lithium ion/lithium polymer battery), or a mixture of a pseudocolloid and a polymer. Since no polymer capable of efficiently transporting lithium ions at room temperature has been found, most lithium ion/lithium polymer batteries are actually hybrid batteries incorporating a pseudocolloid and a polymer. The performance parameters of the general battery mainly include the maximum charging voltage, open circuit voltage, power state, charge and discharge capacity, and internal resistance and capacity of the battery. The performance parameters must be provided by the battery supplier to the design circuit for power loss analysis to obtain the corresponding use of the first charger 321 and the second charger 322 respectively. The power dissipation is related to the input voltage and charging current, and these analyses will be provided for use when designing the core controller 33.

In addition, the two sensors 31 are a current sensor 311 and a sense of voltage. The detector 312, if the charging current is too large, may also cause the battery temperature to be too high, which not only causes damage to the battery and may cause an explosion; therefore, when charging a large current, it is also necessary to use a temperature sensor to detect the temperature of the battery. Therefore, the charging can be stopped when the set charging temperature is exceeded to ensure safety. The charging system 30 further includes a feedback network 34 through which the two sensors 31 feedback the two feedback signals, such as a voltage signal and a current signal, to the core control. The voltage signal and the current signal are provided by the core controller 33 to determine which mode the battery 10 is currently in. The control action of the core controller 33 will be described more closely later.

Furthermore, in this embodiment, the first charging mode is a constant current (constant-current) charging mode. The second charging mode is a constant-voltage charging mode. Because the current general battery charger often uses a three-stage charging method, that is, a pre-charging mode or trickle current mode, a fast charging mode or a constant current mode, and a constant voltage charging mode ( Constant voltage mode); a well-designed charger that repairs an over-discharged battery, that is, pre-processes before formal charging to reduce the passivation film dissolved in an over-discharged state; in addition, when the battery is over-discharged, The internal resistance of the battery will increase. If the battery is charged with a large current, it will cause the battery to overheat, and the pre-charging stage can avoid this phenomenon. However, since the present invention does not focus on the design focus at this stage, it will not be described.

Please refer to FIG. 2, which is a battery 10 of a preferred embodiment of the present invention. When the charging system 30 is charging, the battery terminal voltage and the charging current vary with the charging time. As can be seen from FIG. 2, the battery terminal voltage and charging current and charging time of the battery 10 in the constant current charging mode and the constant voltage charging mode. Relationship. As can be seen from the figure, at the initial stage of charging, since the power is exhausted, the battery terminal voltage is much lower than the input voltage of the power source 20. Therefore, in the constant current charging mode, at this stage, the battery voltage rises with a relatively fast slope, with As the battery power storage increases, the battery voltage rise slope will gradually decrease, and rise to near the time when the battery is full of its rated voltage value, the constant current charging phase ends, at which time the charger is charged with a fixed voltage. When charging in the constant voltage phase, the voltage is almost constant, but the charging current continues to decrease; when the charging current drops to a certain value, a timer is usually started, and after a period of time, the charging is completed, and the charging process is completed.

Currently available battery charging architecture with switched architecture charger (switching-mode charger), linear charger and charge pump. Each has its own advantages and disadvantages and application characteristics. In the case of a switch-type architecture charger, it is suitable for operation in a case where the input-input voltage difference is large, and is also suitable for a high output current, and the efficiency is the highest, and the temperature problem is easily solved. The price is also high, but there is a problem of high electromagnetic interference (EMI) or output chopping, which is more troublesome in the layout of the board.

The linear architecture charger has the advantage of being easy to use, just for input and output. Adding an external capacitor to each end, the material cost is the lowest, and there is no high electromagnetic interference or output chopping problem; when the input voltage is equal to the output voltage, the efficiency can reach more than 85%, and the input voltage is much higher than the output voltage. When the efficiency is reduced to less than 25%, the charger is prone to heat. The charge pump architecture charger has higher circuit efficiency than the linear architecture charger; the electromagnetic interference and output ripple are lower than the switched architecture charger.

According to the actual application, conversion efficiency, service life and charging time, etc. The current integrated power management components on the market are still dominated by switched architecture chargers and linear architecture chargers, but combining the advantages of both to properly switch both to achieve higher efficiency, there are known methods to The series connection combines the two, but the present invention discloses that the two are combined in parallel, and the conversion efficiency is more effectively improved by a control core switching. Therefore, in this embodiment, the first charger 321 can be a switching-mode power converter. The second charger 322 can be a low drop linear regulator (LDO). Moreover, the switchable charger 32 further includes a switch (which can be a 2-1 multiplexer) or two switch S1, S2, and the core controller 33 is based on the switch. Signal and battery correlation coefficients are granted to switch the switches S1, S2.

Therefore, when the switchable charger 32 is lightly operated during the constant voltage charging phase, The high frequency switching of the switching power converter will cause a large switching loss, which is the main reason for the reduction of conversion efficiency. Therefore, the battery charger of the present invention can switch to the corresponding charging architecture in different charging modes, thereby eliminating power loss caused by high frequency switching, which is the spirit of the present invention, and which charging circuit architecture can be used The relevant parameters of the battery and the analysis of the power loss of the voltage and current are determined and are not limited by the circuit architecture proposed by the present invention. The charging method of the present invention will be more clearly explained below by a method flow chart.

Referring to FIG. 3 again, it is a battery 10 which is a preferred embodiment of the present invention. The flow chart of the charging method first includes the step (S01): (a) providing a charging system 30 for the battery 10 for causing a power source 20 to output a power signal to a battery 10, the charging system 30 comprising: at least Two sensors 31, a switchable charger 32, and a core controller 33. In this step, the battery correlation coefficient provided by the battery supplier is provided to the circuit designer for power consumption analysis of the battery to determine the detailed design of the core controller 33.

Charging method of battery 10 in accordance with a preferred embodiment of the present invention, followed by steps (S02): (b) The voltage signal and the current signal of the battery 10 are measured by the two sensors 31. In addition, in order to protect the battery 10 from being overheated, a temperature sensor may be provided for detection, or other considerations, etc., which are not emphasized in the present invention and will not be described herein.

Charging method of battery 10 in accordance with a preferred embodiment of the present invention, and then including steps (S03): (c) returning the voltage signal and current signal of the battery 10 to the core controller 33 to decide to switch the lithium battery 10 to a first charging mode or a second charging mode. In this step, the design of the core controller 33 depends on the power consumption analysis and the feedback signal; and the first charging mode is a constant current charging mode, and the second charging mode is a certain voltage charging mode.

Charging method of battery 10 in accordance with a preferred embodiment of the present invention, followed by steps (S04): (d) switching the switchable charger 32 by the core controller 33 to selectively provide a first charging signal or a second charging signal to the battery 10; in the constant current charging mode, switching the switching The switch causes the switching power converter to start providing the first charging signal charging, because the input and output voltage difference is large at this stage, so it is suitable to adopt a high-efficiency switching architecture charger; and when the constant voltage charging mode is switched, The switching switch causes the low-dropout linear power converter to start providing the second charging signal charging. Since the input-output voltage difference becomes smaller at this stage, the linear architecture charger can reduce the conversion efficiency loss generated by the switching architecture charger. And power conversion with 85% high efficiency.

The charging method of the battery of the preferred embodiment of the present invention, and finally includes the steps (S05): (e) completing the charging process and removing the power source 20 and the charging system 30 to stop outputting the power signal.

Traditional battery chargers use switching power converters for high conversion efficiency Design. The battery charging process is divided into a constant current charging and a constant voltage charging phase. When the charger is operated at a fixed voltage charging stage, the switching loss due to high frequency switching is the main reason for the reduction of conversion efficiency. Therefore, the present invention proposes a reconfigurable or switchable high efficiency battery charger that switches to a corresponding charging architecture in different charging modes to eliminate power loss due to high frequency switching. The patented technology can effectively improve the conversion efficiency of the light load range in the charging process, and can improve the conversion efficiency by more than 10% compared with the conventional design. And because the conversion efficiency is increased, and the efficiency of converting the power output from the power source into the energy stored in the battery is improved, Reduce the advantages of charging time. Furthermore, since the conversion efficiency is increased to reduce the waste heat caused by the power loss, the problems caused by the overheating of the charging process of the portable device can be alleviated, and the reliability of the internal electronic components in the charging process and the battery are increased. safety.

The present invention has been disclosed in its preferred embodiments, and is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

10‧‧‧Battery

20‧‧‧Power supply

30‧‧‧Charging system

31‧‧‧ Sensor

311‧‧‧ Current Sensor

312‧‧‧Voltage sensor

32‧‧‧Switchable charger

321‧‧‧First Charger

322‧‧‧Second charger

33‧‧‧ core controller

34‧‧‧Responsible network

S1, S2‧‧‧ switch

Claims (9)

A battery charging system for causing a power source to output a power signal to a battery, the charging system comprising: at least two sensors respectively coupled to the battery to sense at least two feedback signals of the battery; The switchable charger includes: a first charger for providing a first charging signal to the battery in a first charging mode, wherein the first charger is a switched power converter; and a second charger, in a second charging mode, connected in parallel to the first charger for providing a second charging signal to the battery, wherein the second charger is a low dropout linear power converter; The core controller controls the switchable charger to switch to the first or second charging mode according to the two feedback signals. The charging system for a battery according to claim 1, wherein the battery is one of a nickel cadmium battery, a nickel hydride battery, a lithium ion battery, and a lithium polymer battery. The charging system of the battery of claim 1, wherein the two sensors are a current sensor and a voltage sensor, respectively. The charging system of the battery of claim 1, wherein the charging system further comprises a feedback network through which the two sensors feed back the two feedback signals to the core Controller. The charging system of the battery of claim 1, wherein the first charging mode is a constant current charging mode. The charging system of the battery of claim 1, wherein the second charging mode is a constant voltage charging mode. The charging system of the battery of claim 1, wherein the switchable charger further comprises a switch, and the core controller switches the switch according to the two feedback signals. A charging method for a battery, comprising the steps of: (a) providing a battery charging system for causing a power source to output a power signal to a battery, the charging system comprising: at least two sensors, a switchable charger And a core controller; (b) measuring the voltage signal and the current signal of the battery by using the two sensors; (c) returning the voltage signal and the current signal of the battery to the core controller to decide to switch the battery Forming a first charging mode or a second charging mode; (d) switching the switchable charger by the core controller to select the first charging mode to provide a first charging signal by a first charger, or selecting the The second charging mode is provided by the second charger to the battery, wherein the first charger is a switched power converter, and the second charger is a low dropout linear power converter; (e) The charging process is completed and the output of the power signal is stopped. The charging method of the battery of claim 8, wherein the first charging mode is a constant current charging mode, and the second charging mode is a certain voltage charging mode.