JP2014033548A - Dc power supply synthesizing device with backflow prevention device having no power loss - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC power supply synthesizing device with a backflow prevention device having no power loss which can prevent backflow without installing a backflow prevention circuit on the DC converter side, and extinguish or extremely reduce power loss generated by installation of a backflow prevention circuit (for example, a backflow prevention diode).SOLUTION: A device for synthesizing power from a plurality of DC power supplies and outputting the synthesized power to a DC load device comprises DC converters which are installed in the plurality of DC power supplies respectively and have a backflow prevention function. The DC converter having the backflow prevention function comprises a backflow prevention circuit including a switch control circuit for turning ON/OFF of power outflow transmitted to the DC load device side, where ON/OFF control of a switch circuit is performed on the basis of a comparison value between a generation voltage value generated in the DC converter and an output voltage value output to the DC load device side.

Description

The present invention relates to a DC power source synthesis device with a backflow prevention device, and more particularly to a DC power source synthesis device with a backflow prevention device without power loss.

  Conventionally, for a device that combines a plurality of DC power supplies, a so-called backflow prevention circuit (a circuit that prevents current from flowing in the opposite direction, for example, a backflow prevention diode) or a DC loader is preferentially supplied with power. Therefore, a device having a DC converter (for example, a PWM chopper circuit) used for the purpose, or both is generally known.

  Here, when synthesizing a plurality of power supplies, if the characteristics of the power supplies (voltages at the time of opening) are different, there is a problem that current flows between the plurality of power supplies.

  For example, as shown in FIG. 4, when there is no backflow prevention circuit on the DC converter 30 or DC converter 31 side, the output voltages V1 and V2 of the DC converters 30 and 31 are V1> V2, and When the load resistance is large (for example, when a load is not connected), there is a problem that current flows to the DC converter 31 side as indicated by an arrow 32 (see FIG. 4).

  In order to prevent this, backflow is prevented by providing backflow prevention circuits 33 and 33 (for example, backflow prevention diodes) as shown in FIG.

However, by providing the above-described backflow prevention circuit 33, a power loss occurs when a current passes through the backflow prevention circuit 33. When a backflow prevention diode is used for the backflow prevention circuit 33, for example, a general diode has a forward voltage of about 0.7 V. If a current of 1 A flows, the power of 0.7 W is lost. There was a problem.

JP 2011-181055 A

The present invention was devised to solve the above-described conventional problems, and can prevent backflow without providing backflow prevention circuits 33 and 33 on the DC converter 30 and DC converter 31 side, and also prevents backflow. Providing a DC power source synthesizing device with a backflow prevention device that can eliminate a power loss caused by providing a circuit 33 (for example, a backflow prevention diode) or can make the power loss extremely small. Is intended

The present invention is an apparatus that combines power from a plurality of DC power supplies and outputs the combined power to a DC loader,
Each DC converter provided in the plurality of DC power supplies has a backflow prevention function,
The configuration of the DC converter having the backflow prevention function is as follows:
In the DC converter, a switch control circuit for turning ON / OFF the outflow of electric power sent to the DC loader side is provided, and the generated voltage value generated in the DC converter circuit and the output output to the DC loader side Compared with the voltage value, based on the comparison value, ON / OFF control of the switch circuit, to make a backflow prevention circuit,
It is characterized by
Or
In combining power from the plurality of DC power supplies, priority can be given to power supply from which DC power supply can be set by setting the priority order.
A DC power source synthesis apparatus with backflow prevention.

  According to the present invention, backflow prevention circuits 33 and 33 are not provided on the DC converter 30 and DC converter 31 side, so that backflow can be prevented and the backflow prevention circuit 33 (for example, backflow prevention diode) is installed. Therefore, it is possible to provide a DC power source synthesizing apparatus with a backflow prevention device that can eliminate the power loss that occurs or make the power loss extremely small.

  That is, backflow prevention can be performed by a control device for a DC converter that allows a plurality of DCs to be combined without using a conventional backflow prevention circuit (for example, a backflow prevention diode).

And by not using a backflow prevention circuit, the loss of the electric power which generate | occur | produces by a backflow prevention circuit can be eliminated.

It is a schematic block diagram of this invention. 1 is an overall schematic configuration diagram of the present invention. It is a flowchart which shows operation | movement of this invention. It is a schematic block diagram (1) of a prior art example. It is a schematic block diagram (2) of a prior art example. It is a schematic block diagram which shows the other Example of this invention.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

  FIG. 1 is a schematic view showing an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a DC converter according to the present invention.

  The DC converter 1 is provided with an output voltage control circuit 2 that controls the output voltage. The output voltage control circuit 2 controls the output side voltage of the first DC power supply 4 or the second DC power supply 5 by, for example, turning on / off the switch circuit 3. In FIG. 1, the ON / OFF control of the switch circuit 3 is performed by a backflow prevention control ON / OFF circuit 6 to be described later, and the output side voltage of the first DC power supply 4 or the second DC power supply 5 is controlled.

  Accordingly, it can be said that the ON / OFF control of the switch circuit 3 is performed and the circuit that controls the output side voltage of the first DC power supply 4 or the second DC power supply 5 is also used as the ON / OFF for the backflow prevention control. .

  The backflow prevention control ON / OFF circuit 6 compares the value of the generated voltage generated by the output voltage control circuit 2 with the output voltage by the voltage comparison circuit 8, and based on this, the ON / OFF of the switch circuit 3 is compared. To control the reverse flow, that is, the direction of the arrow 7 shown in FIG. 1 is not reversed. The direction of the current is generally monitored by monitoring the value of the detection device meter 9 such as an ammeter.

  In the present invention, attention is paid to a control method for controlling the output voltage of the DC converter 1 as a method for preventing current from flowing between the power supplies (so-called reverse flow), and this is also used in the control for preventing reverse current. It was. That is, the function of the backflow prevention circuit is realized by using the switch circuit 3 included in the DC converter 1 and the circuit for turning on / off the switch circuit 3 and controlling the switch circuit 3 so as not to backflow. .

Here, the switch circuit 3 is a semiconductor switch (a transistor, an FET, an IGBT, or the like), and controls an output voltage and an output current according to a pulse width by, for example, PWM control.
The output voltage control circuit 2 is a circuit that generates a signal for controlling ON / OFF of the switch circuit 3, and controls the power flowing to the output by the pulse width or the pulse interval.

  Here, reference numeral 9 denotes a current detection device (for example, a shunt resistor, a current transformer, etc.), and the current detected by the current detection device 9 is in the reverse direction (the direction opposite to the arrow 7 in FIG. 1). In this case, or when the voltage detected by the voltmeter 10 is compared by the voltage comparison circuit 8 and the output voltage VO> the generated voltage Vs, the switch circuit 3 is forcibly turned off. When the generated voltage (Vs) is higher than the output voltage (VO), the ON / OFF control of the switch circuit 3 is returned to the normal control method.

  By doing in this way, it can prevent that an electric current flows into a reverse direction. An example of processing is shown in the flowchart of FIG.

Next, the operation of the present invention will be described in detail.
(Reverse current interruption)
It is assumed that a current flows in the direction opposite to the arrow 7 in FIG. 1 due to some voltage fluctuation or the like.
At this time, a reverse current is detected by the current detection device 9 in the DC converter 1. When the reverse current is detected, the switch circuit 3 is disconnected and the current becomes zero. Therefore, it is possible to prevent backflow by maintaining this state.

When the switch circuit 3 is turned on, the current flows in the direction opposite to the arrow 7 in FIG. 1 in the DC converter 1 in a state where the generated voltage VS <the output voltage VO. While the above is established, the switch circuit 3 is maintained in the OFF state. That is, the DC converter 1 is in a disconnected state and can prevent a reverse current from flowing.
(Return from reverse current)

  In the DC converter 1 shown in FIG. 1, when the condition of generated voltage VS <output voltage VO is not satisfied, this means that even if the switch circuit 3 is turned on, the current flows in the direction opposite to the arrow 7 in FIG. In this case, the normal DC converter 1 can be controlled.

  Here, the normal control of the DC converter 1, that is, the control of the output voltage may adopt any configuration. For example, the switch circuits 3-1, 3-3 are configured so as to keep VO constant. It is conceivable that the switching cycle of 2 is controlled by a so-called PWM so as to be a constant voltage (for the switch circuit 3-2, the normal DC converter 1 is controlled even when the switch circuit 3-1 is disconnected. It does not matter.)

  With this configuration, not only the reverse current state can be detected, but also the switch circuit 3 is cut off and the reverse current is blocked when the condition for the reverse current to flow is satisfied. Only when the reverse current does not flow, the direct-current converter 1 controls the normal output voltage. As described above, the DC converter 1 has been frequently described, but the same description applies to the DC converter 2.

(Power source selection)
By applying this principle, it is possible to select which one of a plurality of DC power supplies 4 and 5 is used.

  For example, the voltage range of the DC loader 11 is set to 100 V to 150 V, the target voltage of the DC converter 1 in the first DC power supply 4 (generated voltage VS1) is 140 V, and the target of the DC converter 1 in the second DC power supply 5 is set. When the voltage (assumed to be the generated voltage VS2) is set to 120V, the switch circuit 3 is turned ON when the load voltage is smaller than the generated voltage in any DC converter 1, so the load voltage becomes 120V or higher. .

  Here, assuming that the first DC power supply 4 can sufficiently cover the power of the load, the power is supplied from the first DC power supply 4 and the load voltage becomes 140V. At this time, since the load voltage 140V> VS2 (120V), the switch circuit of the DC converter 1 of the second DC power supply 5 is turned OFF, and power is supplied only from the first DC power supply 4.

  When the first DC power supply 4 alone cannot cover the load, the load voltage decreases. Here, when the load voltage falls below 120V, the load voltage <VS2 (120V), so that the switch circuit 3 of the DC converter 1 of the second DC power supply 5 is turned ON, and the first DC power supply 4 and the first DC power supply 4 Power is supplied to the load from both the two DC power sources 5.

  The power distribution of the first DC power supply 4 and the second DC power supply 5 is determined by the power supply capacity and voltage setting. The first DC power supply 4 is output between 0V and 140V, but the second DC power supply 5 is set to 0 to 120V, so that the first DC power supply 4 is balanced near 120V. This shortage is compensated by the second DC power supply 5.

  On the other hand, regarding the voltage setting, if the DC converter 1 of the second DC power supply 5 is set to a high voltage (for example, 140 V) and the DC converter 1 of the first DC power supply 4 is set to a low voltage (for example, 120 V), this time, When power is supplied from the second DC power supply 5 and the load power cannot be covered only by the second DC power supply 5, power is supplied from both the first DC power supply 4 and the second DC power supply 5.

  The same processing can be performed when there are three or more DC power supplies, and a plurality of power supplies can be selected by voltage setting.

  For example, when three DC power supplies are connected as shown in FIG. 6, if the voltage of the DC converter 30 is set to 120V, the voltage of the DC converter 31 is set to 110V, and the voltage of the DC converter 34 is set to 100V, the load is hardly applied. When the power source 1 and the DC converter 30 can provide the power, the output voltage is 120 V, and no current flows from the DC converter 31 and the DC converter 34.

  When the current flowing through the load is large and the power supplied from the DC converter 30 cannot be covered, the output voltage drops, and when the voltage reaches 110 V, the power is also supplied from the DC converter 31. When the power of the power source 1 and the power source 2 can cover the power to the load, the output voltage is 110V. When the load is further large and cannot be covered by the power source 1 and the power source 2, the output voltage decreases, and the power from the power source 3 is supplied when the output voltage reaches 100V. In this way, the priority of power supply can be determined by setting the voltages for the three power supplies as well.

  For priority selection, for example, a high voltage is set for a low-cost power supply, then a lower voltage is set for a low-cost power supply, and a low voltage is set for a high-cost power supply. By setting the height, it is possible to select and supply power with priority given to cost for any number of power supplies.

  Similarly, it is possible to set environment-priority power by setting voltages in order of decreasing load on the environment, or it is possible to set priorities based on the amount of power that can be supplied.

These settings are the same for four or more power supplies.
In this example, the configuration as the booster circuit has been described. However, the same power supply selection can be performed by setting the target voltage in the same manner as described above in the configuration of the step-down circuit.

DESCRIPTION OF SYMBOLS 1 DC converter 2 Output voltage control circuit 3 Switch circuit 4 1st DC power supply 5 2nd DC power supply 6 ON / OFF circuit 7 for backflow prevention control Arrow 8 Voltage comparison circuit 9 Current detection apparatus 10 Voltmeter 11 DC loader 30 DC Converter 31 DC converter 32 Arrow 33 Backflow prevention circuit 34 DC converter

Claims (2)

A device that combines power from a plurality of DC power supplies and outputs the combined power to a DC loader,
Each DC converter provided in the plurality of DC power supplies has a backflow prevention function,
The configuration of the DC converter having the backflow prevention function is as follows:
In the DC converter, a switch control circuit for turning ON / OFF the outflow of electric power sent to the DC loader side is provided, and the generated voltage value generated in the DC converter and the output output to the DC loader side Compared with the voltage value, based on the comparison value, ON / OFF control of the switch circuit, to make a backflow prevention circuit,
A DC power source synthesis apparatus with a backflow prevention device without power loss.
In combining power from the plurality of DC power supplies, priority can be given to power supply from which DC power supply can be set by setting the priority order.
2. A DC power source synthesizing apparatus with a backflow prevention device without power loss according to claim 1.

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