JP5807283B2 - Power conversion device using a combination of intermediate taps of battery cells connected in series, a balance circuit, and a DC-DC converter - Google Patents

Description

  The present invention relates to a power conversion device, and more particularly to a power supply system that can reduce switching loss and noise and improve conversion efficiency by lowering the input voltage and output voltage of a DC-DC converter.

  In general, in order to operate any device with electric power, it is necessary to supply power within a predetermined operating voltage range determined by the characteristics of the device. This is because electronic devices operate within a predetermined voltage range according to individual characteristics, but operation becomes unstable or non-operation outside the operating voltage range. In this regard, when a storage cell such as a capacitor, an electric double layer capacitor, or a secondary battery is used as a power source, the power source is configured as a storage module in which a plurality of these storage cells are connected in series, thereby summing up each storage cell voltage. As the voltage, the output voltage can be adjusted to a desired value.

  In this case, since the output voltage of the power storage module varies according to the charge / discharge state of each power storage cell, it is generally necessary to stabilize the output voltage using a DC-DC converter or the like. Examples of power supply systems configured to adjust the output voltage to a load using a step-down converter, a step-up converter, and an inverting buck-boost converter as DC-DC converters are shown in FIGS. 1 to 3, respectively.

In the power supply system 100 of FIGS. 1 to 3, the power storage module 102 including the power storage cells C _{1 to} C _n is connected to the load 104 via any one of the DC-DC converters 111, 112, and 113. . These converters, the coil L, the diode D, the switch Sw, and an input capacitor C _in, and the output capacitor C _out. The input / output voltage conversion ratio is determined by a time ratio (duty) defined as a ratio of the on period of the switch to the switching period of the switch Sw.

In discharge power supply system 100 of FIG. 1 using the step-down DC-DC converter 111, the voltage of C _out is lower than the voltage of C _in. That is, the output voltage of the converter 111 is lower than the input voltage. If the input voltage to the converter 111 is V _in and the time ratio of the switch Sw is d, the output voltage V _out is d × V _in . On the other hand, in the power supply system 100 of FIG. 2 using a step-up DC-DC converter 112 is than the voltage of C _out is higher than the voltage of C _in, i.e. higher than the output voltage is input voltage of the converter 112. Output voltage V _out in this case is _{V in / (1-d)} . On the other hand, in the power supply system 100 of FIG. 3 using the inverting buck-boost converter 113, the output voltage can be made higher or lower than the input voltage by appropriately selecting the time ratio. In this case, the output voltage V _out is (d × V _in ) / (1-d). However, when the power supply system of FIG. 3 is used, the polarity of the output voltage is inverted by the converter 113.

1 to 3, the power storage module 102 is connected to the output side of each of the DC-DC converters 111 to 113, and an arbitrary power source 105 is connected to the input side, whereby the power source 105 is used. Thus, the charging power supply system 200 for charging the power storage module 102 can be configured. In such a power supply system 200 shown in FIGS. 4 to 6, any one of the DC-DC converters 111, 112, and 113 is provided between the power supply 105 and the power storage module 102, and thus applied to the power storage module 102. In other words, it is possible to adjust the voltage applied to each of the storage cells C _{1 to} C _n .

  When storage cells such as capacitors, electric double layer capacitors, secondary batteries, etc. are charged at a voltage equal to or higher than a predetermined maximum voltage determined by the characteristics of each storage cell, these storage cells are overcharged. The life span is significantly shortened. Charging at a voltage significantly higher than the maximum allowable voltage or charging for a long time at a voltage higher than the maximum voltage may lead to ignition or rupture of the storage cell. Similarly, if each power storage cell is charged with a current larger than a specified value determined by its characteristics, the power storage cell may be damaged. In order to avoid such a problem, generally, a DC-DC converter or the like is used as shown in FIGS. 4 to 6 to perform charging while controlling the voltage and current to the power storage module.

T. Misyhima, “Experimental Evaluation of the EDLC-based Power Compensator for a Partially Shaded PV Array,” IEEE Industrial Electronics Society, 2003. pp. 1308-1313 Utsumi, et al., “Maximum output control in a photovoltaic power generation system using a multistage boost chopper”, Proceedings of the 2007 Annual Conference of the Institute of Electrical Engineers of Japan, pp.106

  However, in the power supply system shown in FIG. 1 to FIG. 6, since the configuration that suppresses the input voltage to the DC-DC converter or the output voltage from the DC-DC converter is not taken, There is a problem that loss, noise, and recovery loss of the diode accompanying switching of the switch become large.

Specifically, in the power supply system 100 shown in FIGS. 1 to 3, since all the storage cells C _{1 to} C _n constituting the storage module 102 are connected to the input side of the DC-DC converter, If the cell voltage is Vc, the input voltage to the DC-DC converter is n × Vc. The output voltage is equal to the voltage V _{Load of the} load 104. In the power supply system shown in FIGS. 4 to 6, all the storage cells C _{1 to} C _n constituting the storage module 102 are connected to the output side of the converter, and the output voltage from the converter is n × Vc. Yes. The input voltage at this time is equal to the voltage V _{PS of the} power source 105.

In the DC-DC converter in each of the power supply systems of FIGS. 1 to 6, the voltage fluctuation range of the switching node 106 due to switching is 0 to V _{in in} the step-down converters of FIGS. In the step-up converter of FIGS. 2 and 5, 0 to V _out , and in the inverting buck-boost converter of FIGS. 3 and 6, V _in to −V _out . The greater the voltage fluctuation range, the greater the loss associated with switching, noise, and the recovery loss of the diode. That is, in order to suppress these losses and noises, it is preferable to reduce the input / output voltage of the converter that defines the voltage fluctuation range of the switching node 106. However, as described above, in the conventional power supply system, the storage cells C _{1 to} C _n are all connected to the input side or output side of the converter, and all the storage cell voltages contribute to the input or output of the converter. ing.

Further, when the voltage fluctuation range of the switching node 106 is large, it is necessary to use a high breakdown voltage element as the switch Sw and the diode D. Specifically, in the step-down converter of FIG. 1, V _in = n × Vc, in the step-up converter of FIG. 2, V _out = (n × Vc) / (1-d), and inversion of FIG. In the buck-boost converter, each element must have at least a withstand voltage against a voltage of V _in + V _out = (n × Vc) / (1-d). Similarly, V _in = (n × Vc) / d _in the step-down converter of FIG. 4, V _out = n × Vc in the step-up converter of FIG. 5, and in the inverting buck-boost converter of FIG. Each element must have a voltage resistance against a voltage of V _in + V _out = (n × Vc) / d (in any case, the forward voltage drop in the diode D is ignored). .

  Generally, a high withstand voltage switch has a higher on-resistance and a slower switching speed than a low withstand voltage switch, so it is desirable to use a low withstand voltage switch from the viewpoint of efficiency. Similarly, since a high breakdown voltage diode has a larger forward drop voltage and a longer reverse recovery time than a low breakdown voltage diode, it is desirable to use a low breakdown voltage diode from the viewpoint of efficiency. Also from this point, it is necessary to reduce the input / output voltage of the converter in order to suppress the voltage fluctuation range of the switching node 106 and enable the use of a low breakdown voltage element.

  In order to solve the above-mentioned problem, the first invention of the present invention is a power storage cell group configured by connecting in series two or more power storage cells including one or more power storage elements, and electrically connected to the power storage cell group. Any of a balance circuit that adjusts the voltage applied to each of the storage cells, a first input terminal that is electrically connected to one end of the storage cell group, and a series connection point that connects the storage cells to each other in the storage cell group A DC-DC converter having a second input terminal electrically connected to the first and a first and second output terminal, wherein the second input terminal and the second output terminal are electrically connected. An output voltage of the DC-DC converter, which is a potential difference between the first output terminal and the second input terminal, between the first output terminal and the other end of the storage cell group, and the storage cell Group of inputs to the DC-DC converter And outputs the voltage of the storage cell not, the total voltage of, to provide a power supply system.

In accordance with the above configuration, an intermediate tap or the like is provided at the series connection point of the storage cells, and then the DC-DC converter input terminal is connected, and only a part of the storage cells included in the storage cell group is used for input to the converter. Thus, the input voltage V _in of the converter and the output voltage V _out obtained by amplifying or reducing the input voltage V _in according to the time ratio can be reduced. Note that in this case, the discharge speed differs between the storage cells that contribute to the input to the converter and the storage cells that do not contribute, but the variation in the storage cell voltage due to the difference in the discharge speed depends on the operation of the balance circuit. It will be resolved.

  The first invention of the present invention is particularly excellent as a step-down DC-DC converter or a discharge power supply system using a step-up DC-DC converter, as will be described in detail in Example 1 described later. The power supply system of 1 invention is not necessarily restricted to these.

  Further, the second invention of the present invention includes a storage cell group configured by connecting two or more storage cells each including one or more storage elements in series, and each of the storage cells electrically connected to the storage cell group. Electrically connected to any one of a balance circuit for adjusting the applied voltage, a first input terminal electrically connected to one end of the storage cell group, and a series connection point connecting the storage cells in the storage cell group A DC-DC converter having a second input terminal connected to the first and second output terminals, wherein the first input terminal and the first output terminal are electrically connected; An output voltage of a DC-DC converter, which is a potential difference between the second output terminal and the second input terminal, between the second output terminal and the other end of the storage cell group, and a DC-DC in the storage cell group Of storage cells that do not contribute to the input to the converter And outputting the pressure, the total voltage of, to provide a power supply system.

  4 shows another aspect of the power supply system of the present invention. The specific circuit configuration of the power supply system can be changed as appropriate according to the type of DC-DC converter to be incorporated. The second invention of the present invention is particularly excellent as a discharge power supply system using an inverting buck-boost type DC-DC converter, which will be described in detail in Example 2 described later. However, the power supply system of the second invention is not limited to this. It is not done.

  In addition, the third invention of the present invention provides a storage cell group configured by connecting two or more storage cells each including one or more storage elements in series, and each of the storage cells electrically connected to the storage cell group. Electrically connected to any one of a balance circuit for adjusting the applied voltage, a first input terminal electrically connected to one end of the storage cell group, and a series connection point connecting the storage cells in the storage cell group A DC-DC converter having a second input terminal connected to the first and second output terminals, wherein the second output terminal and the other end of the storage cell group are electrically connected; The output voltage of the DC-DC converter, which is a potential difference between the first output terminal and the second input terminal, between the first output terminal and the second output terminal, and the DC-DC in the storage cell group Of storage cells that do not contribute to the input to the converter And outputting the pressure, the total voltage of, to provide a power supply system.

  The third invention corresponds to a variation obtained by changing a specific circuit configuration in the power supply system of the first invention. Similar to the first invention, the third invention is particularly excellent as a step-down DC-DC converter or a discharge power source system using a step-up DC-DC converter, which will be described in detail in Example 3 described later. However, the power supply system of the third invention is not limited to these.

  Further, the fourth invention of the present invention includes a storage cell group configured by connecting two or more storage cells each including one or more storage elements in series, and each of the storage cells electrically connected to the storage cell group. Electrically connected to any one of a balance circuit for adjusting the applied voltage, a first input terminal electrically connected to one end of the storage cell group, and a series connection point connecting the storage cells in the storage cell group A DC-DC converter having a second input terminal connected to the first and second output terminals, wherein the first output terminal and the other end of the storage cell group are electrically connected; The output voltage of the DC-DC converter, which is a potential difference between the second output terminal and the second input terminal, between the second output terminal and the first output terminal, and the DC-DC in the storage cell group Of storage cells that do not contribute to the input to the converter And outputting the pressure, the total voltage of, to provide a power supply system.

  The fourth invention corresponds to a variation obtained by changing a specific circuit configuration in the power supply system of the second invention. Similar to the second invention, the fourth invention is also particularly excellent as a discharge power supply system using an inverting buck-boost type DC-DC converter, which will be described in detail in Example 4 to be described later. The system is not limited to this.

  In addition, the fifth invention provides a storage cell group configured by connecting two or more storage cells each including one or more storage elements in series, and each of the storage cells electrically connected to the storage cell group. Electrically connected to any one of a balance circuit for adjusting the applied voltage, a first output terminal electrically connected to one end of the storage cell group, and a series connection point connecting the storage cells in the storage cell group A DC-DC converter having a second output terminal connected to the first and second input terminals, wherein the second output terminal and the second input terminal are electrically connected; An input voltage of the DC-DC converter, which is a potential difference between the first input terminal and the second output terminal, and a power source electrically connected between the one input terminal and the other end of the storage cell group Is more in the storage cell group than the power supply voltage supplied by the power supply. There wherein the lower by a voltage of no storage cells between the first and second output terminals of the DC-DC converter, to provide a power supply system.

  In accordance with the above configuration, the output terminal of the DC-DC converter is connected to the series connection point of the storage cells and the output terminal of the DC-DC converter is connected, and the output voltage from the converter is supplied to only a part of the storage cells included in the storage cell group. By doing so, the output voltage from the converter can be reduced. Further, if the circuit configuration taught by the present invention is employed as described above, the input voltage of the converter is not stored between the first and second output terminals of the converter in the storage cell group than the power supply voltage supplied by the power supply. The total voltage of the cell, that is, the storage cell that does not receive a direct voltage output from the converter, is lowered.

  In this case, the charging speed differs between the storage cell that directly receives the output from the converter and the storage cell that does not receive the direct output, but the variation in the storage cell voltage due to the difference in the charging speed is balanced circuit. It is solved by the operation.

  The fifth invention is particularly excellent as a charging power source system using a step-down DC-DC converter or a step-up DC-DC converter, as will be described in detail in Example 5 described later. The power supply system of 5 invention is not necessarily restricted to these.

  In addition, the sixth invention provides a storage cell group configured by connecting two or more storage cells each including one or more storage elements in series, and each of the storage cells electrically connected to the storage cell group. Electrically connected to any one of a balance circuit for adjusting the applied voltage, a first output terminal electrically connected to one end of the storage cell group, and a series connection point connecting the storage cells in the storage cell group A DC-DC converter having a second output terminal connected to the first and second input terminals, wherein the first input terminal and the first output terminal are electrically connected; An input voltage of the DC-DC converter, which is a potential difference between the second input terminal and the second output terminal, and a power source electrically connected between the two input terminals and the other end of the storage cell group Is more in the storage cell group than the power supply voltage supplied by the power supply. There wherein the lower by a voltage of no storage cells between the first and second output terminals of the DC-DC converter, to provide a power supply system.

  4 shows another aspect of the power supply system of the present invention. The specific circuit configuration of the power supply system can be changed as appropriate according to the type of DC-DC converter to be incorporated. The sixth invention of the present invention is particularly excellent as a charging power supply system using an inverting buck-boost type DC-DC converter, which will be described in detail in Example 6 described later. However, the power supply system of the sixth invention is not limited to this. It is not done.

  Note that a capacitor, an electric double layer capacitor, a secondary battery, or the like can be used as an example of the power storage cell.

  According to the power conversion device of the present invention, it is possible to reduce the loss and noise caused by switching by reducing the input / output voltage of the DC-DC converter. In addition, since the withstand voltage conditions required for devices such as capacitors and coils constituting the DC-DC converter are relaxed, components such as input / output capacitors and coils occupying a large proportion of the size and weight of the DC-DC converter. As a result, it is possible to use a small device with a low withstand voltage, thereby achieving downsizing of the converter. Note that the power conversion device of the present invention is provided with a balance circuit, and the variation in voltage caused by the progress of charging / discharging in the capacitors connected in series is eliminated. Therefore, there is no possibility that the lifetime of the entire module is shortened by applying a high voltage only to some of the capacitors.

It is a circuit diagram which shows the conventional power supply system for discharge provided with the pressure | voltage fall type DC-DC converter. It is a circuit diagram which shows the conventional power supply system for discharge provided with the pressure | voltage rise type DC-DC converter. It is a circuit diagram which shows the conventional power supply system for discharge provided with the inverting buck-boost type DC-DC converter. It is a circuit diagram which shows the conventional power supply system for charge provided with the pressure | voltage fall type DC-DC converter. It is a circuit diagram which shows the conventional power supply system for charge provided with the pressure | voltage rise type DC-DC converter. It is a circuit diagram which shows the conventional power supply system for charging provided with the inverting buck-boost type DC-DC converter. 1 is a circuit diagram showing a first embodiment of a power supply system according to the present invention. It is the circuit diagram which showed the switched capacitor which can be used as an example of a balance circuit. 1 is a circuit diagram showing a configuration using a step-down DC-DC converter as a converter in a first embodiment of a power supply system according to the present invention. FIG. 1 is a circuit diagram showing a configuration using a step-up DC-DC converter as a converter in a first embodiment of a power supply system according to the present invention. FIG. It is a circuit diagram which shows 2nd Embodiment of the power supply system which concerns on this invention. In 2nd Embodiment of the power supply system which concerns on this invention, it is a circuit diagram which shows the structure which used the inverting buck-boost type DC-DC converter as a converter. It is a circuit diagram which shows 3rd Embodiment of the power supply system which concerns on this invention. In 3rd Embodiment of the power supply system which concerns on this invention, it is a circuit diagram which shows the structure which used the pressure | voltage fall type DC-DC converter as a converter. In 3rd Embodiment of the power supply system which concerns on this invention, it is a circuit diagram which shows the structure which used the pressure | voltage rise type DC-DC converter as a converter. It is a circuit diagram which shows 4th Embodiment of the power supply system which concerns on this invention. In 4th Embodiment of the power supply system which concerns on this invention, it is a circuit diagram which shows the structure which used the inverting buck-boost type DC-DC converter as a converter. It is a circuit diagram which shows 5th Embodiment of the power supply system which concerns on this invention. In 5th Embodiment of the power supply system which concerns on this invention, it is a circuit diagram which shows the structure which used the pressure | voltage fall type DC-DC converter as a converter. In 5th Embodiment of the power supply system which concerns on this invention, it is a circuit diagram which shows the structure which used the pressure | voltage rise type DC-DC converter as a converter. It is a circuit diagram which shows 6th Embodiment of the power supply system which concerns on this invention. In 6th Embodiment of the power supply system which concerns on this invention, it is a circuit diagram which shows the structure which used the inverting buck-boost type DC-DC converter as a converter.

  Hereinafter, an embodiment of a power supply system according to the present invention will be described with reference to FIGS. As the converter used in the power supply system, a non-insulated step-down type, step-up type, inverting buck-boost type DC-DC converter is exemplified as an example. It is also possible to use it. It is also possible to use an insulating converter such as a flyback converter, a forward converter, a push-pull converter, or a bridge converter.

Configuration of Discharge Power Supply System 1 FIG. 7 shows a discharge power supply system 1 that can be implemented as the first invention. C _{1 to} C _n are power storage cells such as capacitors, electric double layer capacitors, and secondary batteries, and the power storage module 102 is configured by connecting them in series. It is assumed that the balance circuit 101 is connected to the power storage module 102 and the voltages of the power storage cells C _{1 to} C _n are always kept equal by the balance circuit 101.

The balance circuit 101 may be a circuit configured as a switched capacitor system including capacitors C _{s, 1 to} C _{s, n-1} and switches Q _{1 to} Q _2n as shown in FIG. 8, for example.

When the switched capacitor system of FIG. 8 is used as the balance circuit 101, the capacitors C _{s, 1 to} C _{s, n-1} and the storage cells C _{1 to} C _n are mutually charged and discharged by high-speed switching of the switches Q _{1 to} Q _2n. As a result, the voltage shared by each storage cell becomes uniform.

Specifically, when the odd numbered switches Q ₁ , Q ₃ ,... Q _2n-1 are on, the storage cell C ₁ and the capacitor C _{S, 1} are connected to each other, and C ₂ and C _{S, 2} are. Since C _n-1 and C _{S, n-1} are respectively connected in parallel, when there is a variation in voltage between the storage cells and capacitors connected in parallel, mutual charging / discharging occurs. This is done in a direction that eliminates voltage variations. On the other hand, when the even-numbered switches Q ₂ , Q ₄ ,... Q _2n are on, the storage cell C ₂ and the capacitor C _{S, 1} , C ₃ and C _{S, 2 ,.} And C _{S, n-1} are connected in parallel to each other. Therefore, when there is a voltage variation between the storage cells and capacitors connected in parallel, mutual charge / discharge is performed, and the voltage variation Head to the direction where is resolved.

Therefore, by repeating switching between a state in which all odd-numbered switches are turned on and a state in which all even-numbered switches are turned on, each power storage cell is directly or indirectly connected to all other power storage cells. Therefore, mutual charging / discharging is performed (through other capacitors), and the voltages of the storage cells C _{1 to} C _n are made uniform. As a switch used in the balance circuit, it is convenient to use an electronic switch (semiconductor switch) that can be switched at high speed, such as an FET, a thyristor, or a photo MOS FET. The same applies to a switch Sw used in a DC-DC converter described later. However, the switches that can be used in the power supply system of the present invention are not limited to these. The switching can be performed by switching a voltage applied to the gate of the transistor, for example, using an arbitrary switch driver (not shown) as a switch control means.

Furthermore, (in the energy storage cell C _n, terminal on the side not connected to the storage cell C _n-1 adjacent) end of the battery module 102 is connected to the first input terminal IN1 of the DC-DC converter 103, further An intermediate tap taken out from the connection point between C _m and C _{m + 1} is connected to the second input terminal IN2. Accordingly, among the power storage cells C _{1 to} C _n constituting the power storage module 102, C _{m + 1 to} C _{n in} particular supply power directly to the DC-DC converter 103.

The load 104 is connected to the first output terminal OUT1 of the DC-DC converter 103 and a terminal on the return side of the power storage module 102 (a terminal on the power storage cell C ₁ that is not connected to the adjacent power storage cell C ₂ ). Yes. The return-side terminal is grounded. Further, the second input terminal IN2 and the second output terminal OUT2 of the DC-DC converter 103 are connected.

Operation of Discharge Power Supply System 1 Next, when a discharge operation is performed by the discharge power supply system 1, the input / output voltage of the DC-DC converter 103, the voltage applied to the load 104, the current flowing through the load 104, and A discharge current flowing through each of the storage cells C _{1 to} C _n constituting the balance circuit 102 will be described.

In FIG. 7, I _Load indicates the current flowing through the load 104 when the DC-DC converter 103 is operated. Similarly, I _L and I _U indicate discharge currents flowing through C _{1 to} C _m and C _{m + 1 to} C _n when the DC-DC converter 103 is operated, respectively.

As already mentioned, one first input terminal IN1 of the DC-DC converter 103 is connected to one end of the power storage module 102, a second input terminal IN2 is taken out from a connection point between C _m and C _{m + 1} intermediate The storage cells that are connected to the tap and thus directly contribute to the input to the converter 103 are C _{m + 1 to} C _n . Therefore the input voltage V _in to the converter 103, the voltage of each storage cells C ₁ -C _n, which is homogenized by the balance circuit 101 When Vc, can be expressed by the following equation (1).
V _in = (nm) × Vc (1)
However, in the present embodiment 1, the input voltage V _in, is defined as the potential difference between the first input terminal and the second input terminal. The same applies to subsequent Examples 2 to 4.

  When the configuration shown in FIGS. 1 to 3 is adopted, the input voltage to the converters 111 to 113 is (n × Vc). According to the configuration of FIG. It can be kept low.

Here, it is assumed that the DC-DC converter 103 in FIG. 7 operates without loss. Assuming that the output voltage V _out of the converter 103 is a potential difference between the first output terminal OUT1 and the second input terminal IN2, and the output current I _out of the converter 103 is a current flowing _out from the first output terminal OUT1, Equation (2) is established.
I _U × (n−m) × Vc = V _out × I _out (2)
However, I _U in the above equation (2) does not include current that flows into or out of the storage cells C _{m + 1 to} C _n by the operation of the balance circuit.

When considering the power supply system 1 as a whole, the following equation (3) is established from the energy conservation law, assuming that the load voltage applied to the load 104 is V _Load .
I _U × (n−m) × Vc + I _L × m × Vc = V _Load × I _Load (3)
However, I _U and I _L in the above equation (3) do not include currents flowing into or out of the storage cells C _{1 to} C _n by the operation of the balance circuit.

Since the load voltage V _Load is equal to the sum of the voltages C _{1 to} C _m and the output voltage V _out of the converter, the following equation (4) is established.
V _Load = m × Vc + V _out (4)
For the load current I _Load , the following equation (5) is established.
I _Load = I _out = I _L (5)

From the expressions (2) and (5), the following expression (6) is derived as a relational expression between I _U and I _L.
I _U = (V _out × I _L ) / {(n−m) × Vc} (6)

As shown in the equation (6), I _U and I _L are different values except when V _out = (nm) × Vc. If I _U and I _L are not equal, a variation due to a difference in discharge rate occurs between the cell voltages of C _{1 to} C _{m and} the cell voltages of C _{m + 1 to} C _n . However, even in such a case, the operation of the balance circuit 101 tends to eliminate the variation between the storage cell voltages. Therefore, the power supply system shown in FIG. 7 can be stably operated.

Specific Example Using Step-Down Converter A power supply system 1 configured using a step-down DC-DC converter 111 is shown in FIG. 9 as a specific example of the discharge power supply system 1 shown in FIG. The converter 111 temporarily converts the input voltage from the storage cells C _{m + 1 to} C _n into a high-frequency square wave voltage by switching the switch Sw on and off, and rectifies and smoothes this to output a DC output voltage. Supply. The relationship between the input voltage V _in and the output voltage V _out of the step-down converter 111 is expressed by the following (7) using a time ratio d (0 ≦ d ≦ 1) that is a ratio of the ON period of the switch to the switching period of the switch Sw. ) Expression.
V _out = d × V _in = d × (n−m) × Vc (7)

From the above equations (7) and (4), the load voltage V _Load is expressed as follows.
V _Load = {d × (n−m) + m} × Vc (8)
When the storage cells C _{1 to} C _n are directly connected to the load 104 without using the DC-DC converter 111, a voltage of n × Vc is applied to the load 104. Therefore, the discharge power supply system 1 of FIG. It can be seen that is performing step-down operation. According to the equation (8), the magnitude of the load voltage V _Load is m × Vc which is the sum of the voltages of the storage cells C _{1 to} C _m not directly connected to the DC-DC converter 111, and the DC-DC converter. It is equal to the sum of d × (n−m) × Vc, which is the output voltage of 111.

Next, the relationship between I _U and I _L in the discharge power supply system 1 of FIG. 9 is obtained. By substituting the equation (7) that holds for the output voltage _Vout when using the step-down converter into the relational equation (6) satisfied by I _U and I _L , a specific equation as shown in the following equation (9) The following relational expression is obtained.
I _U = d × I _L (9)
However, both I _U and I _L in the above equation (9) do not include currents flowing into the storage cells C _{1 to} C _n or flowing out of C _{1 to} C _n by the operation of the balance circuit 101. .

As shown in the above equation (9), in the discharge power supply system 1 of FIG. 9, I _U ≦ I _L , and the storage cells C _{1 to} C _m discharge more rapidly than the storage cells C _{m + 1 to} C _n. . Therefore, voltage variation occurs between the storage cells, but such variation is eliminated by the operation of the balance circuit 101, so that the power supply system 1 can be stably operated.

In the configuration of FIG. 9, the potential difference between the switching node 106 of the DC-DC converter 111 and the second input terminal IN2 can be expressed as V _in = (n−m) × Vc using the equation (1). it can. On the other hand, the potential difference between the switching node 106 and the second input terminal IN2 in the conventional configuration of FIG. 1 is n × Vc. That is, according to the configuration of FIG. 9, the voltage applied to the switching node 106 can be suppressed lower than that of the conventional case by m × Vc corresponding to the contribution of the cell voltages C _{1 to} C _m .

  Therefore, according to the discharge power supply system 1 of the present invention shown in FIG. 9, the switching loss, the recovery loss in the diode, and the noise generated by the switching can be suppressed to be smaller than those in the conventional configuration shown in FIG. In addition, in the conventional configuration shown in FIG. 1, it is necessary to use a device having a voltage resistance against a voltage of at least n × Vc as the switch Sw and the diode D, but the elements used in the power supply system 1 in FIG. It is sufficient if it has a voltage resistance against a voltage of (nm) × Vc. That is, it becomes possible to select a device having a lower withstand voltage than the conventional one, which leads to a reduction in the size of the entire power supply system. The size and weight of the DC-DC converter is dominated by the input and output capacitors and coils. By keeping the input and output voltage of the converter low, the size of the capacitor per unit capacitance and the size of the coil per unit ripple current Can also be reduced in size.

Specific Example Using Boost Type Converter As another specific example of the discharge power source system 1 shown in FIG. 7, a power source system 1 configured using a boost type DC-DC converter 112 is shown in FIG. The converter 112 once converts the input voltage from the storage cells C _{m + 1 to} C _n into a high-frequency square wave voltage by switching on / off of the switch Sw, and rectifies and smoothes this to output a DC output voltage. Supply. Relationship between the input voltage V _in and the output voltage V _out of _the boost converter 112 when using the ratio d (0 ≦ d ≦ 1) , represented by the following equation (10).
V _out = V _in / (1-d) = {(nm) × Vc} / (1-d) (10)

Equation (4) is established between the load voltage V _Load and the output voltage V _out . By substituting the above equation (10) into the equation (4), the load voltage V _Load is obtained as shown in the following equation (11).
V _Load = m × Vc + {(n−m) × Vc} / (1-d) (11)
When the storage cells C _{1 to} C _n are directly connected to the load 104 without using the DC-DC converter 112, a voltage of n × Vc is applied to the load 104. Therefore, the discharge power supply system 1 in FIG. It can be seen that the boost operation is performed. According to the equation (11), the magnitude of the load voltage V _Load is m × Vc which is the sum of the voltages of the storage cells C _{1 to} C _m not directly connected to the DC-DC converter 112, and the DC-DC converter. It is equal to the sum of {(n−m) × Vc} / (1−d), which is the output voltage of 112.

Next, the relationship between I _U and I _L in the discharge power supply system of FIG. 10 is obtained. By substituting the equation (10) that holds for the output voltage _Vout when using the boost converter 112 into the relational equation (6) that is satisfied by I _U and I _L , the following equation (12) is obtained. The following relational expression is obtained.
I _U = I _L / (1-d) (12)
However, both I _U and I _L in the above equation (12) do not include the current flowing into the storage cells C _{1 to} C _n or flowing out of C _{1 to} C _n by the operation of the balance circuit 101. .

As shown in the above equation (12), in the discharge power supply system 1 of FIG. 10, I _U ≧ I _L , and the storage cells C _{m + 1 to} C _n discharge more rapidly than the storage cells C _{1 to} C _m. . Therefore, voltage variation occurs between the storage cells, but such variation is eliminated by the operation of the balance circuit 101, so that the power supply system 1 can be stably operated.

In the configuration of FIG. 10, the potential difference between the switching node 106 of the DC-DC converter 112 and the second input terminal IN2 is expressed as V _out = {(n−m) × Vc} / ( 1-d). On the other hand, the potential difference between the switching node 106 and the second input terminal IN2 in the conventional configuration of FIG. 2 is (n × Vc) / (1-d). That is, according to the configuration of FIG. 10, the voltage applied to the switching node 106 is lower than the conventional one by (m × Vc) / (1−d) corresponding to the contribution of the cell voltage of C _{1 to} C _m. Can be suppressed.

  Therefore, according to the discharge power supply system 1 of the present invention shown in FIG. 10, the switching loss, the recovery loss in the diode, and the noise generated by the switching can be suppressed to be smaller than those in the conventional configuration shown in FIG. In addition, in the conventional configuration shown in FIG. 2, it is necessary to use a device having a withstand voltage against a voltage of (n × Vc) / (1-d) at least as the switch Sw and the diode D. Thus, it is sufficient that the elements used in the power supply system 1 of FIG. 10 have a withstand voltage against a voltage of {(n−m) × Vc} / (1-d). That is, it becomes possible to select a device having a lower withstand voltage than the conventional one, which leads to a reduction in the size of the entire power supply system.

As a configuration DC-DC converter of the discharge power supply system 1 , an inverting buck-boost converter can be used. FIG. 11 shows a circuit configuration of a discharge power supply system 1 suitable for incorporating an inverting buck-boost converter, which can be implemented as an example of the second invention. Unlike the case where the second input terminal IN2 and the second output terminal OUT2 of the DC-DC converter 103 are connected in FIG. 7, in the circuit configuration of FIG. 11, the first input terminal IN1 and the first output terminal IN1 Is connected.

Specific Example Using Inverting Buck-Boost Type Converter FIG. 12 shows an example using an inverted buck-boost type DC-DC converter 113 as a DC-DC converter in the system shown in FIG. The converter 113 temporarily converts the input voltage from the storage cells C _{m + 1 to} C _n into a high-frequency square wave voltage by switching the switch Sw on and off, and rectifies and smoothes this to output a DC output voltage. Supply. The voltage of the output capacitor C _out is represented using the voltage V _in of the input capacitor C _in the _{(d × V in) / (} 1-d). However, the polarity is reversed as indicated by the “+” symbol in FIG. If the output voltage V _out of the converter 113 is defined as a potential difference between the second output terminal OUT2 and the second input terminal IN2, V _out is expressed by the following equation (13).
V _out = V _in + (d × V _in ) / (1−d)
= {(Nm) * Vc} / (1-d) (13)

Expression (13) is the same as Expression (10) representing the output voltage when the step-up DC-DC converter 112 is used. In the circuit configuration of FIG. 12, since the equations (4) and (6) are established as in the case of using the boost converter 112, the load voltage V _Load when using the inverting buck-boost converter 113 is ( 11) and the relationship between I _U and I _L is expressed by equation (12). That is, the discharge power supply system 1 in FIG. 12 using the inverting buck-boost converter 113 has substantially the same operating characteristics as the discharge power supply system 1 in FIG. 10 using the boost converter 112.

  Note that the specific discharge power supply system described with reference to FIGS. 7 to 12 is merely an example for carrying out the first and second inventions, and the present invention has a different configuration. It is also possible.

  For example, each power storage cell constituting the power storage module 102 may be a power storage cell formed by connecting a plurality of arbitrary power storage elements.

The balance circuit 101 is not limited to the specific circuit shown in FIG. The balance circuit 101 may be an arbitrary circuit configured to adjust the ratio of the magnitudes of the voltages of the storage cells C _{1 to} C _{m and} the voltages of C _{m + 1 to} C _n to a predetermined value, for example. . As described above, the magnitude of the load voltage V _Load is equal to the sum of the voltages of the storage cells C _{1 to} C _m that are not directly connected to the DC-DC converter and the output voltage V _out of the DC-DC converter. Therefore, when adjusting the load voltage by controlling the DC-DC converter, the voltage of C _{1 to} C _m that determines the reference point of the load voltage and the voltage of C _{m + 1 to} C _n that determines the adjustment range by the converter In some cases, it is preferable to set each of them separately. Alternatively, in order to keep the reference point of the load voltage constant while the voltage of each storage cell drops due to discharge, the ratio of the magnitudes of the voltage of C _{1 to} C _{m and} the voltage of C _{m + 1 to} C _n is set. The balance circuit can also be configured so as to change appropriately as the discharge progresses. The reference point of the load voltage and the adjustment range by the converter can also be set by changing the position where the intermediate tap is to be taken out (changing m in the range of 1 ≦ m ≦ n−1).

  In the following Examples 3 to 8, specific embodiments can be appropriately changed in the same manner. All of these variations are included in the technical scope of the present invention.

Configuration of Discharge Power Supply System 1 FIG. 13 shows a discharge power supply system 1 that can be implemented as the third invention obtained by partially changing the circuit configuration of the discharge power supply system 1 shown in FIG. Is shown. In the configuration of FIG. 7, the second output terminal OUT2 is connected to the second input terminal IN2, whereas in the configuration of FIG. 13, the second output terminal OUT2 is connected to the return-side terminal of the power storage module 102. .

Operation of Discharge Power Supply System 1 Next, the relationship between each voltage and current when the discharge operation is performed by the discharge power supply system 1 of FIG. 13 will be described. First, the storage cells that directly contribute to the input to the converter 103 are C _{m + 1 to} C _n as in FIG. 7 and the like, and the formula (1) is also established in the third embodiment.

Also in the discharge power supply system 1 of FIG. 13, the formula (3) is established as the energy conservation law of the entire system. Similarly to the discharge power supply system 1 of FIG. 7, if the output voltage _Vout of the converter 103 is defined as a potential difference between the first output terminal OUT1 and the second input terminal IN2, the configuration of FIG. ) Is established. Further, the expression (5) is established for the load current I _Load as in the configuration of FIG.

From the formulas (3), (4), and (5), the above formula (6) is derived as a relational formula between I _U and I _{L in} the configuration of FIG.

As shown in the equation (6), except for the case where V _out = (n−m) × Vc, I _U and I _L have different values, and the cell voltages vary, but the operation of the balance circuit 101 By eliminating this, stable operation of the system becomes possible.

Specific Example Using Step-Down Converter FIG. 14 shows a power supply system 1 configured using a step-down DC-DC converter 114 as a specific example of the discharge power supply system 1 shown in FIG. The converter 114 once converts the input voltage from the storage cells C _{m + 1 to} C _n into a high-frequency square wave voltage by switching the switch Sw on and off, and rectifies and smoothes this to output a DC output voltage. Supply. The output voltage V _out of the step-down converter 114 is expressed by the above equation (7) using the time ratio d (0 ≦ d ≦ 1) as in the configuration of FIG. From the above formulas (7) and (4), the load voltage V _Load is expressed by formula (8) as in the power supply system shown in FIG.

Next, the relationship between I _U and I _L in the discharge power supply system 1 of FIG. 14 is obtained. If the expression (7) that holds for the output voltage _Vout when the step-down converter 114 is used is substituted into the relational expression (6) that satisfies I _U and I _L , the above expression (9) is derived. That is, the relationship between I _U and I _L is expressed by equation (9) as in the power supply system shown in FIG.

  As described above, the discharge power supply system 1 of FIG. 14 has substantially the same operating characteristics as the discharge power supply system 1 of FIG.

Specific Example Using Boosting Converter As another specific example of the discharge power supply system 1 shown in FIG. 13, a power supply system 1 configured using a boosting DC-DC converter 115 is shown in FIG. The converter 115 temporarily converts the input voltage from the storage cells C _{m + 1 to} C _n into a high-frequency square wave voltage by switching the switch Sw on and off, and rectifies and smoothes this to output a DC output voltage. Supply. The output voltage V _out of the step-up converter 115 is expressed by the above equation (10) in the same manner as the configuration of FIG. 10 using the time ratio d (0 ≦ d ≦ 1). From the above equations (10) and (4), the load voltage V _Load is expressed by equation (11) as in the power supply system shown in FIG.

Next, the relationship between I _U and I _L in the discharge power supply system 1 of FIG. 15 is obtained. By substituting the above equation (10) that holds for the output voltage _Vout when using the step-up converter 115 into the relational equation (6) that satisfies I _U and I _L , the above equation (12) is derived. That is, the relationship between I _U and I _L is expressed by equation (12) as in the power supply system shown in FIG.

  As described above, the discharge power supply system 1 of FIG. 15 has substantially the same operating characteristics as the discharge power supply system 1 of FIG.

Configuration of Discharge Power Supply System 1 FIG. 16 shows a discharge power supply system 1 that can be implemented as the fourth invention obtained by partially changing the circuit configuration of the discharge power supply system 1 shown in FIG. Is shown. In the configuration of FIG. 11, the first output terminal OUT1 is connected to the first input terminal IN1, whereas in the configuration of FIG. 16, the first output terminal OUT1 is connected to the return-side terminal of the power storage module 102. .

Operation of Discharge Power Supply System 1 Next, the relationship between each voltage and current when the discharge operation is performed by the discharge power supply system 1 of FIG. 16 will be described. First, the storage cells that directly contribute to the input to the converter 103 are C _{m + 1 to} C _n as in FIG. 7 and the like, and the formula (1) is also established in the fourth embodiment.

Also in the discharge power supply system 1 of FIG. 16, the formula (3) is established as the energy conservation law of the entire system. Similarly to FIG. 11, if the output voltage V _out of the converter 103 is defined as a potential difference between the second output terminal OUT2 and the second input terminal IN2, the output voltage V _out and the load voltage V _Load are Equation (4) is established. Similarly, the formula (5) is established for the load current I _Load .

From the equations (3), (4), and (5), the above equation (6) is derived as a relational expression between I _U and I _L.

As shown in the equation (6), except for the case where V _out = (n−m) × Vc, I _U and I _L have different values, and the cell voltages vary, but the operation of the balance circuit 101 By eliminating this, stable operation of the system becomes possible.

Specific Example Using Inverting Buck-Boost Type Converter FIG. 17 shows an example using an inverting buck-boost type DC-DC converter 116 as a DC-DC converter in the system shown in FIG. The converter 116 temporarily converts the input voltage from the storage cells C _{m + 1 to} C _n into a high-frequency square wave voltage by switching the switch Sw on and off, and rectifies and smoothes this to output a DC output voltage. Supply. _Vout defined as a potential difference between the second output terminal OUT2 and the second input terminal IN2 is expressed by the equation (13) as in the power supply system of FIG. Further, since the formula (4) is established in the configuration of FIG. 17, the load voltage V _Load is expressed by the formula (11) similarly to the power supply system 1 of FIGS. 10, 12, and 15. Furthermore, if the equation (13) is substituted into the above equation (6), the relational expression satisfied by I _U and I _L is the same as that in the case of using the power supply system of FIGS. 10, 12 and 15 ( 12) is derived.

  As described above, the discharge power supply system 1 in FIG. 17 has substantially the same operating characteristics as the discharge power supply system 1 in FIGS. 10, 12, and 15.

Configuration of Charging Power Supply System 2 FIG. 18 shows a charging power supply system 2 that can be implemented as the fifth invention. C _{1 to} C _n are power storage cells such as capacitors, electric double layer capacitors, and secondary batteries, and the power storage module 102 is configured by connecting them in series. It is assumed that the balance circuit 101 is connected to the power storage module 102 and the voltages of the power storage cells C _{1 to} C _n are always kept equal by the balance circuit 101. As the balance circuit 101, the switched capacitor system shown in FIG. 8 can be used, but as described above, any other balance circuit may be used.

Furthermore, (in the energy storage cell C _n, terminal on the side not connected to the storage cell C _n-1 adjacent) end of the battery module 102 is connected to the first output terminal OUT1 of the DC-DC converter 103, further An intermediate tap taken out from the connection point between C _m and C _{m + 1} is connected to the second output terminal OUT2. Therefore, among the power storage cells C _{1 to} C _n constituting the power storage module 102, particularly C _{m + 1 to} C _n receive direct power supply from the DC-DC converter 103.

DC power supply 105, a first return side of the terminal of the input terminal OUT1 and the power storage module 102 of the DC-DC converter 103 is connected to (in the energy storage cell C _1, terminal on the side not connected to the storage cell C ₂ adjacent) ing. The return-side terminal is grounded. Further, the second input terminal IN2 and the second output terminal OUT2 of the DC-DC converter 103 are connected.

Operation of Charging Power Supply System 2 Next, when charging operation is performed by the charging power supply system 2, the input / output voltage of the DC-DC converter 103, the voltage supplied from the DC power supply 105, the current flowing through the DC power supply 105, and the charging current flowing in the respective storage cells C ₁ -C _n constituting the balance circuit 102 will be described.

In FIG. 18, _IPS indicates the current flowing through the power source 105 when the DC-DC converter 103 is operated. Similarly, I _L and I _U indicate charging currents flowing through C _{1 to} C _m and C _{m + 1 to} C _n when the DC-DC converter 103 is operated, respectively.

As already mentioned, one first output terminal OUT1 of the DC-DC converter 103 is connected to one end of the power storage module 102, the second output terminal OUT2 is taken out from a connection point between C _m and C _{m + 1} intermediate The storage cells that are connected to the tap and receive the direct voltage output from the converter 103 are C _{m + 1 to} C _n . Therefore, the output voltage V _out from the converter 103 can be expressed by the following equation (19), where Vc is the voltage of each of the storage cells C _{1 to} C _n made uniform by the balance circuit 101.
V _out = (nm) × Vc (14)
However, in the fifth embodiment, the output voltage _Vout is defined as a potential difference between the first output terminal and the second output terminal. The same applies to the subsequent Example 6.

  When the configurations shown in FIGS. 4 to 6 are employed, the output voltage from the converters 111 to 113 is (n × Vc). According to the configuration of FIG. It can be kept low.

Here, it is assumed that the DC-DC converter 103 in FIG. 18 operates without loss. The input voltage V _in of the converter 103 as a potential difference between the first input terminal IN1 and the second output terminal OUT2, when the current flowing the input current I _in of the converter 103 to the first input terminal IN1, the following from the energy conservation law Equation (15) is established.
V _in × I _in = I _U × (nm) × Vc (15)
However, I _U in the above equation (15) does not include current that flows into or out of the storage cells C _{1 to} C _n by the operation of the balance circuit.

When considering the power supply system 2 as a whole, the following equation (16) is established from the law of conservation of energy with the power supply voltage of the power supply 105 as V _PS .
V _PS × I _PS = I _U × (n−m) × Vc + I _L × m × Vc (16)

The power supply voltage V _PS to become equal to the sum of the C ₁ -C _m voltage and converter input voltage V _in, the following (17) is established.
V _PS = m × Vc + V _in (17)
For the power supply current _IPS , the following equation (18) is established.
I _PS = I _in = I _L (18)

From the equations (15) and (18), the following equation (19) is derived as a relational expression between I _U and I _L.
I _U = (V _in × I _L ) / {(n−m) × Vc} (19)

As shown in the equation (19), I _U and I _L are different values except when V _in = (nm) × Vc. If I _U and I _L are not equal, a variation due to a difference in charging speed occurs between the cell voltages of C _{1 to} C _{m and} the cell voltages of C _{m + 1 to} C _n . However, even in such a case, the operation of the balance circuit 101 tends to eliminate the variation between the storage cell voltages. Therefore, the power supply system shown in FIG. 18 can be stably operated.

Specific Example Using Step-Down Converter FIG. 19 shows a power supply system 2 configured using a step-down DC-DC converter 111 as a specific example of the charging power supply system 2 shown in FIG. Relationship between the input voltage V _in and the output voltage V _out of _the buck converter 111, using the time of the switch Sw ratio d (0 ≦ d ≦ 1) , represented by the following equation (20).
V _in = V _out / d = {(n−m) × V _c } / d (20)

From the above equations (20) and (17), the power supply voltage V _PS is expressed as follows.
V _PS = {(n−m) × V _c } / d + m × V _c (21)

From the above equation (21), n × V _c = d × (V _PS −m × V _c ) + m × V _c (22)
It becomes. Furthermore, the following formula (23) is obtained by subtracting V _PS from both sides of the formula (22).
n × V _c −V _ps = (1−d) × (m × V _c −V _ps ) (23)

Here, (1-d) ≧ 0 on the right side of the above equation (23). Further, using the equation (17), it is shown that (m × V _c −V _ps ) = − V _in ≦ 0 (however, the polarity of the power supply voltage V _ps is selected so that V _in ≧ 0) It shall be). Therefore, n × V _c ≦ V _ps , that is, V _c ≦ V _ps / n.

When the storage cells C _{1 to} C _n are directly connected to the power supply 105 without using the DC-DC converter 111, a voltage of (V _ps / n) is applied from the power supply 105 to each storage cell. In other words, it can be seen that the output voltage applied to each storage cell is stepped down by the DC-DC converter 111 from (V _ps / n) to Vc. Further, according to the equation (17), the magnitude of the power supply voltage V _PS is m × Vc, which is the sum of the voltages of the storage cells C _{1 to} C _m not directly connected to the DC-DC converter 111, and DC-DC. It is equal to the sum of {(n−m) × Vc} / d, which is the input voltage of converter 111.

Next, the relationship between I _U and I _L in the charging power supply system 2 of FIG. 19 is obtained. By substituting the equation (20) that holds for the input voltage Vin _{in the} case of using the step-down converter into the relational equation (19) that I _U and I _L satisfy, a specific equation as shown in the following equation (24) is obtained. The following relational expression is obtained.
I _U = I _L / d (24)
However, both I _U and I _L in the above equation (24) do not include current that flows into the storage cells C _{1 to} C _n or flows out of C _{1 to} C _n by the operation of the balance circuit 101. .

As shown in the above equation (24), in the charging power supply system 2 of FIG. 19, I _U ≧ I _L , and the storage cells C _{m + 1 to} C _n are charged more rapidly than the storage cells C _{1 to} C _m. The Therefore, voltage variation occurs between the storage cells, but such variation is eliminated by the operation of the balance circuit 101, so that the power supply system 2 can be stably operated.

In the configuration of FIG. 19, the potential difference between the switching node 106 of the DC-DC converter 111 and the second output terminal OUT2 is expressed as V _in = {(n−m) × Vc} / d using equation (20). It can be expressed as. On the other hand, the potential difference between the switching node 106 and the second output terminal OUT2 in the conventional configuration of FIG. 4 is (n × Vc) / d. That is, according to the configuration of FIG. 19, the voltage applied to the switching node 106 can be suppressed lower than the conventional one by (m × Vc) / d corresponding to the contribution of the cell voltage of C _{1 to} C _m. .

  Therefore, according to the charging power supply system 2 of the present invention shown in FIG. 19, the switching loss, the recovery loss in the diode, and the noise generated by the switching can be suppressed to be smaller than those in the conventional configuration shown in FIG. In addition, in the conventional configuration shown in FIG. 4, it is necessary to use a device having a withstand voltage against a voltage of (n × Vc) / d at least as the switch Sw and the diode D. However, the power supply system 2 in FIG. It is sufficient that the element to be used has a voltage resistance against a voltage of {(n−m) × Vc} / d. That is, it becomes possible to select a device having a lower withstand voltage than the conventional one, which leads to a reduction in the size of the entire power supply system.

Specific Example Using Boosting Converter As another specific example of the charging power supply system 2 shown in FIG. 18, a power supply system 2 configured using a boosting DC-DC converter 112 is shown in FIG. Relationship between the input voltage V _in and the output voltage V _out of _the boost converter 112 when using the ratio d (0 ≦ d ≦ 1) , represented by the following equation (25).
V _in = V _out × (1−d) = {(n−m) × Vc} × (1−d) (25)

Between the power supply voltage V _PS and the input voltage V _in (17) equation is satisfied. By substituting the above equation (25) into the equation (17), the power supply voltage V _PS is obtained as shown in the following equation (26).
V _PS = {(n−m) × Vc} × (1-d) + m × Vc (26)

From the above equation (26), n × V _c = (V _PS −m × V _c ) / (1−d) + m × V _c (27)
It becomes. Further, by subtracting V _PS from both sides of the above equation (27), the following equation (28) is obtained.
_{nV c -V ps = {- d} / (1-d)} × (m × V c -V ps) ... (28)

Here, {−d / (1-d)} ≦ 0 on the right side of the equation (28). Further, using the equation (17), it is shown that (m × V _c −V _ps ) = − V _in ≦ 0 (however, the polarity of the power supply voltage V _ps is selected so that V _in ≧ 0) It shall be). Therefore, nV _c ≧ V _ps , that is, V _c ≧ V _ps / n.

When the storage cells C _{1 to} C _n are directly connected to the power source 105 without using the DC-DC converter 112, a voltage of (V _ps / n) is applied from the power source 105 to each storage cell. In other words, the output voltage applied to each storage cell is boosted by the DC-DC converter 112 from (V _ps / n) to Vc. Further, according to the equation (26), the magnitude of the power supply voltage V _PS is m × Vc which is the sum of the voltages of the storage cells C _{1 to} C _m not directly connected to the DC-DC converter 112, and DC-DC. It is equal to the sum of {(n−m) × Vc} × (1-d), which is the input voltage of the converter 112.

Next, the relationship between I _U and I _L in the charging power supply system 2 of FIG. 20 is obtained. To I _U and I _L and satisfies equation (19), holds the input voltage V _in the case of using a boost converter (25) By substituting the equation, specifically in as shown in the following equation (29) The following relational expression is obtained.
I _U = I _L × (1-d) (29)
However, both I _U and I _L in the above equation (29) do not include currents flowing into the storage cells C _{1 to} C _n or flowing out of C _{1 to} C _n by the operation of the balance circuit 101. .

As shown in the above equation (29), in the charging power supply system 2 of FIG. 20, I _U ≦ I _L , and the storage cells C _{1 to} C _m are charged more rapidly than the storage cells C _{m + 1 to} C _n. The Therefore, voltage variation occurs between the storage cells, but such variation is eliminated by the operation of the balance circuit 101, so that the power supply system 2 can be stably operated.

In the configuration of FIG. 20, the potential difference between the switching node 106 of the DC-DC converter 112 and the second output terminal OUT2 may be expressed as V _out = (nm) × Vc using the equation (14). it can. On the other hand, the potential difference between the switching node 106 and the second output terminal OUT2 in the conventional configuration of FIG. 5 is n × Vc. That is, according to the configuration of FIG. 20, the voltage applied to the switching node 106 can be kept lower than that of the conventional case by m × Vc corresponding to the contribution of the cell voltages C _{1 to} C _m .

  Therefore, according to the charging power supply system 2 of the present invention shown in FIG. 20, the switching loss, the recovery loss in the diode, and the noise generated by the switching can be suppressed to be smaller than those in the conventional configuration shown in FIG. In addition, in the conventional configuration shown in FIG. 5, it is necessary to use a device having a withstand voltage against a voltage of at least n × Vc as the switch Sw and the diode D, but the elements used in the power supply system 2 in FIG. It is sufficient if it has a voltage resistance against a voltage of (nm) × Vc. That is, it becomes possible to select a device having a lower withstand voltage than the conventional one, which leads to a reduction in the size of the entire power supply system.

Configuration of Charging Power Supply System 2 As the DC-DC converter used in the charging power supply system 2, an inverting buck-boost converter can be used. FIG. 21 shows a circuit configuration of the charging power supply system 2 that can be implemented as an example of the sixth invention and is suitable for incorporating an inverting buck-boost converter. Unlike the case where the second input terminal IN2 and the second output terminal OUT2 of the DC-DC converter 103 are connected in FIG. 18, the first input terminal IN1 and the first output terminal IN1 in the circuit configuration of FIG. Is connected.

Specific Example Using Inverting Buck-Boost Type Converter FIG. 22 shows an example using an inverted buck-boost type DC-DC converter 113 as a DC-DC converter in the system shown in FIG. The voltage of the input capacitor C _in is expressed as {(1-d) × V _out } / d using the voltage V _out of the output capacitor C _OUT . However, the polarity is reversed as indicated by the “+” symbol in FIG. By defining the input voltage V _in of the converter 113 as a potential difference between the second input terminal IN2 and the second output terminal OUT2, V _in is represented by the following equation (30).
V _in = {(1−d) × V _out } / d + V _out = {(n−m) × Vc} / d
... (30)

(30) the magnitude of V _in represented by formula is the same as the magnitude of V _in, represented by the input voltage representative of the (20) formula in the case of using a step-down DC-DC converter 111. In the circuit configuration of FIG. 22, since the equations (17) and (19) are established as in the case of using the step-down converter 111, the power supply voltage V _PS when using the inverting buck-boost converter 113 is ( 21) and the relationship between I _U and I _L is expressed by equation (24). That is, the charging power supply system 2 in FIG. 22 using the inverting buck-boost converter 113 has substantially the same operating characteristics as the charging power supply system 2 in FIG. 19 using the step-down converter 111.

  The present invention can be widely applied to a power source using a storage cell such as a secondary battery, an electric double layer capacitor, or a capacitor. For example, in a photovoltaic power generation system, the present invention can be used to control the output voltage of an unstable solar cell that depends on the amount of solar radiation to a desired magnitude. Alternatively, the present invention can be applied to a storage power source.

DESCRIPTION OF SYMBOLS 1 Discharge power supply system 2 Charging power supply system 100 Discharge power supply system 101 Balance circuit 102 Power storage module 103 DC-DC converter 104 Load 105 Power supply 106 Switching node 111 Step-down DC-DC converter 112 Step-up DC-DC converter 113 Inversion elevation pressure type DC-DC converter 200 power system for charging C _in the input capacitor C _out output capacitor D diode L coil S _W, Q ₁ ~Q _2n switches C ₁ -C _n capacitors _{C s, 1 ~C s, n} -1 storage cells IN1 first input terminal IN2 second input terminal OUT1 first output terminal OUT2 second output terminal IL current I _L storage cells C _{1 to} C _m current I _U current storage cells C _{m + 1 to} C _n I _LOAD load current I _PS power supply current

Claims (5)

A storage cell group configured by connecting in series two or more storage cells each including one or more storage elements;
For all storage cells contained in the storage cell group in the direction in which the variation of the voltage applied to each of the storage cells is eliminated, adjusting the voltage applied to the respective storage cells, the accumulating cell group A balance circuit electrically connected to
A first input terminal electrically connected to one end of the storage cell group and a second input terminal electrically connected to any one of the series connection points connecting the storage cells in the storage cell group A DC-DC converter having a first output terminal and a second output terminal, wherein the second input terminal and the second output terminal are electrically connected;
With
An output voltage of the DC-DC converter that is a potential difference between the first output terminal and the second input terminal between the first output terminal and the other end of the storage cell group, and the storage cell group And outputting a total voltage of the storage cell voltage that does not contribute to the input to the DC-DC converter. A storage cell group configured by connecting in series two or more storage cells each including one or more storage elements;
For all storage cells contained in the storage cell group in the direction in which the variation of the voltage applied to each of the storage cells is eliminated, adjusting the voltage applied to the respective storage cells, the accumulating cell group A balance circuit electrically connected to
A first input terminal electrically connected to one end of the storage cell group and a second input terminal electrically connected to any one of the series connection points connecting the storage cells in the storage cell group A DC-DC converter having a first output terminal and a second output terminal, wherein the first input terminal and the first output terminal are electrically connected;
With
An output voltage of the DC-DC converter, which is a potential difference between the second output terminal and the second input terminal, between the second output terminal and the other end of the storage cell group, and the storage cell group And outputting a total voltage of the storage cell voltage that does not contribute to the input to the DC-DC converter. A storage cell group configured by connecting in series two or more storage cells each including one or more storage elements;
For all storage cells contained in the storage cell group in the direction in which the variation of the voltage applied to each of the storage cells is eliminated, adjusting the voltage applied to the respective storage cells, the accumulating cell group A balance circuit electrically connected to
A first output terminal electrically connected to one end of the storage cell group, and a second output terminal electrically connected to any one of series connection points connecting the storage cells in the storage cell group A DC-DC converter having a first input terminal and a second input terminal, wherein the second output terminal and the second input terminal are electrically connected;
A power source electrically connected between the first input terminal and the other end of the storage cell group;
With
The input voltage of the DC-DC converter, which is a potential difference between the first input terminal and the second output terminal, is higher in the storage cell group than the power supply voltage supplied by the power supply. The power supply system is characterized in that it is lower by the voltage of the storage cell not between the first and second output terminals. A storage cell group configured by connecting in series two or more storage cells each including one or more storage elements;
For all storage cells contained in the storage cell group in the direction in which the variation of the voltage applied to each of the storage cells is eliminated, adjusting the voltage applied to the respective storage cells, the accumulating cell group A balance circuit electrically connected to
A first output terminal electrically connected to one end of the storage cell group, and a second output terminal electrically connected to any one of series connection points connecting the storage cells in the storage cell group A DC-DC converter having first and second input terminals, wherein the DC-DC converter is electrically connected to the first input terminal and the first output terminal;
A power source electrically connected between the second input terminal and the other end of the storage cell group;
With
The input voltage of the DC-DC converter, which is the potential difference between the second input terminal and the second output terminal, is higher in the storage cell group than the power supply voltage supplied by the power supply. The power supply system is characterized in that it is lower by the voltage of the storage cell not between the first and second output terminals.   5. The power supply system according to claim 1, wherein the storage cell includes at least one of a capacitor, an electric double layer capacitor, or a secondary battery.

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