JP6696819B2 - Operating point control circuit device for series connected solar cells or other power sources - Google Patents

Description

  The present invention relates to an operating point control circuit device for a solar cell and any other power source (battery, battery, fuel cell, generator, power generating element, etc.), and more specifically, a series connected solar cell or other The present invention relates to an operating point control circuit device for a power supply, which has a configuration capable of controlling a generated voltage or an operating voltage of each battery or a power supply and boosting an output voltage.

  Since the generated voltage of one solar cell (cell) is generally lower than the operating voltage of various machines and chargers, the solar cells are used to operate such machines and chargers and charge the charger. As one of the methods, a configuration in which a plurality of solar battery cells are connected in series (solar battery module) is adopted in a solar power generation system. In such a solar cell module in which a plurality of solar cells are connected in series, a shadow is produced on some cells due to differences in the installation angle of each solar cell, buildings, etc. When the variation occurs, the cell with a small power generation amount becomes a resistance (reverse bias diode), which may reduce the output of the solar cell module.

  More specifically, as is well known in this field, the solar cell has a characteristic that the current changes as the generated voltage increases from 0 V, as illustrated in FIG. 7 (A). The generated power has an optimum operating point (referred to as a maximum power point or an optimum operating point) that maximizes its magnitude. And, in the case of a solar cell module in which a plurality of solar cells are connected in series as described above, the maximum output points of all the solar cells are substantially the same, and therefore all the solar cells connected in series are In the battery cell, it is assumed that the current flows at the common maximum output point, but in reality, as described above, due to shadows, some solar battery cells in the solar battery module In some cases, the amount of received light may decrease, and in that case, only the power generation characteristics of the solar cells with the reduced amount of received light change in the direction in which the current with respect to the generated voltage decreases, and the maximum output point shifts. Then, in a circuit configuration in which solar cells are connected in series, the same current will flow to solar cells whose maximum output points differ from each other, resulting in cells with a small amount of received light (cells with a small amount of power generation). When the current is matched with the maximum output point of the cell having a large amount of received light, it not only does not substantially generate power but also becomes a resistance to the current, which causes a decrease in the output of the solar cell module. (Not only does the power generation output corresponding to the amount of light received by the solar cell module not obtained, but output loss also occurs.)

  Therefore, as a device for avoiding the output reduction due to the variation in the amount of received light for each solar battery cell, it is possible to individually control the operating points of each of the solar battery cells connected in series. Power generation operating point control circuit devices have been proposed (Non-Patent Documents 1 to 3). Such a power generation operating point control circuit device uses a multistage buck-boost chopper circuit for a circuit configuration in which a plurality of solar cells are connected in series, and for each solar cell, a current at each maximum output point The generated voltage is controlled so that all the solar cells can generate electricity at substantially the maximum output point. According to this power generation operating point control circuit device, even a solar battery cell whose light receiving amount is reduced due to a shadow or the like can be operated at its maximum output point, so that the generated power corresponding to the light receiving amount of the solar battery module is generated. Further, since the solar battery cell obtained and having a reduced amount of received light does not serve as a reverse-biased diode, output loss is also reduced.

  Regarding the configuration using the chopper circuit in the operation control of the solar cell, there is an example of a circuit device that can reduce the loss in the switching element and efficiently charge the power generation output of the solar cell in the charger. 1 is proposed.

JP-A-6-284601

Toshihisa Shimizu and 6 others, Proceedings of Solar / Wind Energy, 1996, 57-60 Toshihisa Shimizu, FB Technical News No. 56 Nov. 1, 2000, pp. 22-27 Toshihisa Shimizu et al., “Generation Control Circuit for Photovoltaic Modules” IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL.16, NO. 3, MAY 2001, pp. 293-300.

  In a solar cell module in which a plurality of solar cells are connected in series, both ends of the solar cell module obtained by using the power generation operating point control circuit device as described in Non-Patent Documents 1 to 3 above. The output voltage of is substantially the sum of the voltages when the respective solar cells are generating power at their respective maximum power points. Therefore, when a voltage higher than the sum of the power generation voltages of the plurality of solar cells connected in series is required, for example, charging is performed at a voltage higher than the sum of the power generation voltages of the solar cells. When charging the charger, it is necessary to boost the output voltage of the solar cell module. However, the power generation operating point control circuit devices proposed in the above Non-Patent Documents 1 to 3 do not have a boosting function, and when attempting to boost the output voltage of the solar cell module, the generated power decreases. Will be done. Therefore, in the case of such a power generation operating point control circuit device, in order to boost the output voltage of the solar cell module, a booster is additionally required in addition to the power generation operating point control circuit device. Will increase and cost will increase.

  In this regard, the inventors of the present invention can boost the output voltage of the solar cell module without lowering the generated power by merely modifying a part of the configuration of the power generation operating point control circuit device. I found it possible. The knowledge is utilized in the present invention.

  Thus, one object of the present invention is a power generation operating point control circuit device for controlling the power generation operating point of each solar cell in a solar cell module in which a plurality of solar cells are connected in series, An object of the present invention is to provide a device capable of boosting the output voltage of a solar cell module without lowering the power.

  Further, the configuration of the device in which a part of the configuration of the power generation operating point control circuit device is modified and a function of boosting the output voltage of the solar cell module is added is not limited to the solar cell, and a plurality of batteries, a condenser, a power generator, It can also be used to control the operating voltage of each power supply element in a module in which arbitrary power supply elements such as a machine and a power generation element are connected in series. Therefore, a further object of the present invention is to control the operating points of individual cells in a module in which a plurality of solar cells and power supply elements (battery cells, storage cells, generators, power generation elements, etc.) are connected in series. (EN) Provided is an operating point control circuit device capable of boosting an output voltage of a module without reducing generated power or output power.

  According to the present invention, the above-mentioned problem is a power generation operating point control circuit device for a plurality of solar cells connected in series, wherein a pair of output terminals are connected in series between a pair of output terminals. A plurality of electrode connection terminals connected to the respective electrode terminals of the plurality of solar cells, and a corresponding electrode connection terminal for each of the plurality of solar cells between the pair of output terminals. Between a capacitor and a pair of output terminals that are connected in parallel via each of the plurality of solar cells, are connected in parallel via the corresponding electrode connection terminals and inductors, and connected. And a switching means for selectively conducting the pair of electrode connection terminals to each other, further, between the pair of output terminals, one end side of a plurality of solar cells connected in series Between the electrode connection terminal and one of the output terminals or between the two electrode connection terminals between two adjacent solar cells of the plurality of solar cells connected in series, to the capacitor An additional capacitor is connected in series to the switching device, an additional switching device is connected in parallel to the additional capacitor and in series to the switching device, and the switching device and the additional switching device are the same. In a predetermined cycle, at different times from each other, between the pair of connected electrode connection terminals, between the connected electrode connection terminals and one of the output terminals, and the above-mentioned two electrode connection terminals. Between the corresponding terminals of the electrodes, and at least one of the switching means and the additional switching means is always connected between the pair of electrode connection terminals connected to each other, and the electrode connection connected to each other. A pair of electrodes, which cuts off the continuity between the corresponding terminal among the terminal and one of the output terminals and between the above-mentioned two electrode connection terminals, and other switching means and additional switching means are connected. Switching means and additional switching means so as to establish electrical connection between corresponding connecting terminals for electrodes, one of the connected electrode connecting terminals and one of the output terminals, and between corresponding terminals of the two connecting terminals for electrodes. Is achieved by a device whose conduction is controlled.

  As will be understood from the description with reference to the drawings described later, the above-described device of the present invention is basically connected in series using a multi-stage buck-boost chopper circuit described in Non-Patent Documents 1 to 3. It has the same circuit configuration as the power generation operating point control circuit device for the plurality of solar cells. However, in the case of the device of the present invention, as described above, between one end and one output terminal of the multi-stage buck-boost chopper circuit (circuit comprising solar cells, capacitors, inductors, and switching means) or the multi-stage type Between the stages of the buck-boost chopper circuit of (1), a circuit portion including an additional capacitor and an additional switching means connected in parallel is further added. In the operation of these switching means, as described above, at the same predetermined cycle and at different timings, the connected electrode connection terminals are connected between the pair of connected electrode connection terminals. Between the terminal and one of the output terminals, or between the corresponding terminals of the two electrode connection terminals respectively connected to the two adjacent solar cells, the conduction between the corresponding terminals is interrupted, and at that time, the switching means is always provided. And one of the additional switching means is connected between the pair of connected electrode connection terminals, between the connected electrode connection terminals and one of the output terminals, or connected to two adjacent solar cells, respectively. The conduction of the switching means and the additional switching means is controlled so as to cut off the conduction between the corresponding terminals of the two electrode connection terminals.

  According to the configuration of the above circuit device, due to the presence of the circuit portion in which the additional capacitor and the switching means are connected in parallel, the output voltage between the pair of output terminals can be increased without decreasing the generated power. It is possible to make the value higher than the total sum of the power generation voltages of the plurality of solar battery cells when all the battery cells generate power at their respective maximum operating points. That is, in the configuration of the circuit device described above, it is possible to boost the voltage between the output terminals without adding a booster to the output terminals.

  In this regard, in more detail, as already mentioned, the solar cell generally has a characteristic that the current changes with respect to the generated voltage as shown in FIG. Then, preferably, using a voltage or current controller such as an MPPT controller that executes Maximum Power Point Tracking (MPPT), the output voltage between the terminals of the solar cell (that is, the generated voltage) is Adjusted. That is, in short, in the case of a solar cell module in which the output voltage between terminals of the solar cell is controlled to a voltage set by a voltage or current controller such as an MPPT controller, and solar cells are connected in series. In addition, the output voltage across the solar cell module is controlled by the voltage or current controller. At that time, in the circuit configuration in which solar cells are connected in series, as already mentioned, there is a shift in the maximum power point among a plurality of solar cells due to a shift in the amount of received light. Where output loss occurs, using the power generation operating point control circuit device (Non-Patent Documents 1 to 3) as described above makes it possible to individually adjust the power generation voltage of each solar cell, so that the MPPT controller In adjusting the output voltage across the solar cell module by such voltage or current controllers, it becomes possible to realize a state in which all the solar cells connected in series generate power at the maximum power point. However, even when the power generation operating point control circuit device of Non-Patent Documents 1 to 3 is used, the output voltage between the terminals of the solar cell is set higher than the sum of the generated voltage at the maximum power point of each solar battery cell. If set to a value, the generated voltage of at least one solar battery cell will deviate from the maximum power point, and the generated power will decrease.

  On the other hand, in the case of the configuration of the device of the present invention, that is, the circuit portion in which the additional capacitor and the switching means are connected in parallel between the output terminals of the power generation operating point control circuit devices of Non-Patent Documents 1 to 3 is added. In the case of the configuration, when the output voltage adjusted by the voltage or current controller such as the MPPT controller is higher than the sum of the generated voltage at the maximum power points of the solar cells connected in series, the voltage or The differential pressure between the output voltage adjusted by the current controller and the sum of the generated voltage at the maximum power point of each solar cell can be held by the additional capacitor. Therefore, each solar cell performs a power generation operation at each maximum power point, and the output voltage across the solar cell module is higher than the sum of the generated voltage at each maximum power point of the solar cell. The state of being held at the voltage is realized. Then, since each solar battery cell is performing the power generation operation at each maximum power point, it is possible to substantially reduce the generated power.

  In the above configuration, the circuit configuration is a so-called step-up / down chopper circuit, and the generated voltage of each solar cell and the holding voltage of the additional capacitor are the conduction and interruption of conduction in the switching means and the additional switching means. And the height of each of these voltages is adjusted by the ratio of the time width (off-time duty ratio) that interrupts conduction for a predetermined period in the switching means and the additional switching means. It is determined. Then, as described in the section of the embodiment below, the off-time duty ratio of each switching means is the generated voltage of the corresponding solar battery cell of each switching means with respect to the output voltage across the corresponding solar battery module. Alternatively, it is the holding voltage of the additional capacitor (the voltage difference obtained by subtracting the sum of the generated voltage of the photovoltaic cells from the output voltage between the pair of output terminals with respect to the output voltage between the pair of output terminals). Therefore, in the above-described configuration of the device of the present invention, the ratio of the time width for interrupting the conduction between the pair of connected electrode connection terminals to the predetermined cycle of each of the switching means is determined by the pair of output terminals. Is a ratio of the (required or preferred) generated voltage of the corresponding solar cell of each of the switching means to the output voltage of the solar cell in which the output voltage between the pair of output terminals is connected in series. When the voltage is higher than the sum of the generated voltage, it is connected between one of the connected electrode connection terminals and one of the output terminals for a predetermined cycle of the additional switching means or two connected solar cells, respectively. The ratio of the time width for interrupting the conduction between the two electrode connection terminals is the voltage obtained by subtracting the sum of the generated voltage of the photovoltaic cells from the output voltage between the pair of output terminals with respect to the output voltage between the pair of output terminals. The conduction and interruption in the switching means and the additional switching means may be controlled as is the ratio of the differences.

  As can be understood from the above description, the maximum generated power that can be extracted from the solar cell module is when each solar cell is generating power at the generated voltage at its maximum power point. Thus, in the above-mentioned device of the present invention, the output voltage between the pair of output terminals may be a desired voltage, and the conduction between the pair of connected electrode connection terminals for a predetermined cycle of the switching means. The ratio of the time widths for shutting off the cells may be adjusted so that the generated voltage of the corresponding solar battery cell becomes the voltage at the maximum operating point.

  In general, in a solar power generation system, when the environmental conditions of the solar cell, for example, the environmental conditions such as the amount of received light and temperature change, the generated voltage of the solar cell is changed in real time according to the change. The voltage or current controller, such as an MPPT controller, is often configured to sequentially monitor the generated power of the solar cell and perform adjustment of the generated voltage. Has been done. Similarly, also in the device of the present invention, it is preferable that the power generation voltage of each solar battery cell in the solar battery module can be sequentially adjusted. In this regard, as described above, in the case of the device of the present invention, the generated voltage of each solar cell is such that the pair of electrode connection terminals connected to the predetermined cycle of the switching means connected in parallel to each other. It is adjusted by the ratio of the time widths that interrupt the conduction between. Therefore, in the above-mentioned device of the present invention, for the pair of electrodes connected to each predetermined cycle of the switching means so that the generated voltage of the solar cells connected in series becomes the voltage at the maximum operating point. Means may be further provided for adjusting the ratio of the time widths for interrupting the conduction between the connection terminals. Such means is based on a change in generated power monitored by a voltage or current controller such as an MPPT controller for adjusting an output voltage between a pair of output terminals, so that the generated power is maximized. It may be configured to appropriately change a ratio of time widths for interrupting conduction between a pair of connected electrode connection terminals for each predetermined cycle.

  By the way, if a plurality of the above-mentioned devices of the present invention are prepared and are connected in parallel, a larger amount of current can be obtained. Accordingly, in another aspect of the invention, a device may be provided in which a pair of output terminals of a plurality of the devices of the invention described above are connected in parallel with each other.

  In addition, the circuit configuration of the device of the present invention is a device that outputs any electric power, such as a rechargeable battery (chemical battery) cell, a storage battery cell, a fuel battery cell, a generator or a power generation device (hereinafter, referred to as a solar battery). , Devices including solar cells that output arbitrary electric power are referred to as "power cells". Modules, solar cells, chemical cells, battery cells and / or other power cells The present invention can be applied to a module or the like in which are mixed and connected in series, and the power generation and / or discharge operation of the module is performed while adjusting the operating voltage of each cell. Therefore, in still another aspect of the present invention, in the circuit configuration of the device of the present invention described above, at least a part of the solar cell may be replaced with a chemical battery cell or a battery cell.

  According to yet another aspect of the present invention, there is provided an operating point control circuit device for a plurality of power supply cells connected in series, wherein a pair of output terminals are connected in series between the pair of output terminals. Between the plurality of electrode connection terminals connected to the respective electrode terminals of the plurality of power supply cells and the pair of output terminals, through the corresponding electrode connection terminals for each of the plurality of power supply cells. Connected in parallel between a capacitor and a pair of output terminals, each of the plurality of power supply cells is connected in parallel via a corresponding electrode connection terminal and an inductor, and is connected in a pair. And a switching means for selectively conducting the electrode connection terminals with each other, and further, between the pair of output terminals, the electrode connection terminals on one end side of the plurality of power supply cells connected in series. Between one of the output terminals and one of the output terminals, or between two electrode connection terminals between two adjacent power cells of a plurality of power cells connected in series, and added in series to the capacitor. Is connected in parallel to the additional capacitor and in series with the switching means, the additional switching means is connected, and the switching means and the additional switching means are in the same predetermined cycle. Correspondence between a pair of connected electrode connection terminals, between a connected electrode connection terminal and one of the output terminals, and between the two electrode connection terminals at different times. The connection between the connecting terminals for connecting the electrodes and the output terminal is always between one of the connecting terminals for the pair of connected electrodes, and one of the switching means and the additional switching means. Between and between the corresponding terminals of the two electrode connection terminals, other switching means and additional switching means, between the pair of electrode connection terminals connected, The conduction of the switching means and the additional switching means is controlled so that conduction is established between the connected electrode connection terminal and one of the output terminals and between the corresponding terminals of the two electrode connection terminals. A device is provided. The configuration of the operation control of the operating point control circuit device applied to any of the above power supply cells may be the same as that in the case of the power generation operating point control circuit device for a solar cell. A plurality of operating point control circuit devices applied to a device in which at least a part of a solar cell is replaced with a chemical battery cell or a battery cell or an arbitrary power supply cell may be prepared and used by connecting them in parallel. Therefore, a pair of output terminals of an operating point control circuit device applied to a plurality of the above-mentioned devices or power supply cells of the present invention in which at least a part of the solar battery is replaced with a chemical battery cell or a battery cell are connected in parallel with each other. Provided device may be provided.

  Thus, according to the above-mentioned device of the present invention, as described above, it is possible to boost the output voltage of the solar cell module in which a plurality of solar cells are connected in series without decreasing the generated power. .. Therefore, even if a voltage higher than the sum of the generated voltage when multiple solar cells are operating at the maximum power point is required depending on the specifications of the machinery and charger to be operated, separately In addition, the need for a booster is eliminated, and an increase in system size or cost can be avoided.

  By the way, the circuit configuration of the above-mentioned device of the present invention is basically the same as the configuration in which one solar battery cell is removed in the power generation operating point control circuit devices of Non-Patent Documents 1 to 3. As already mentioned, in the case of the power generation operating point control circuit devices of Non-Patent Documents 1 to 3, the solar cells are connected to all the stages of the multi-stage buck-boost chopper circuit. If the voltage across both ends does not match the sum of the generated voltage when all the solar cells generate power at the maximum power point, the generated voltage of any of the solar cells will deviate from the maximum power point, The generated power of the solar battery cell is reduced, and the generated power obtained by the entire solar battery module is reduced. For example, in a solar battery module in which n solar battery cells are connected in series, the output voltage of the solar battery module is equal to the sum of the generated voltage when the n solar battery cells generate power at the maximum power point. If there is not, the power for n solar cells cannot be obtained. On the other hand, in the case of the present invention, even if the voltage across the buck-boost chopper circuit becomes higher than the sum of the generated voltage when all the solar cells generate power at the maximum power point, the difference is added. Since it is held by the capacitor of, all the solar cells can be in a state of generating power at the maximum power point. For example, in the case of a solar cell module in which n solar cells are connected in series, a configuration of an n + 1-stage buck-boost chopper circuit is prepared, and the output voltage of the solar cell module is n solar cells. Even if the generated voltage is higher than the sum of generated voltages when the cells generate power at the maximum power point, all n solar cells can generate power at the maximum power point. Therefore, n solar cells can be generated. The power for the minute is obtained. In other words, according to the configuration of the present invention, the generated voltage of all the solar cells generated at the maximum power point without reducing the power obtained from all the power generation capacities of the prepared solar cells. Since an output voltage higher than the sum total can be obtained, all the solar cells can be effectively used, and the increase in the size and cost of the solar cell module can be suppressed. The same applies when the device of the present invention is applied to an arbitrary power cell, depending on the operating characteristics of the power cell.

  Other objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the present invention.

FIG. 1A is an exemplary circuit configuration diagram of one embodiment of a power generation operating point control circuit device according to the present invention, and FIG. 1B is an exemplary time of an ON / OFF state of a switching element. It is a figure which shows a chart. FIG. 1 (C) is an exemplary circuit configuration diagram of one embodiment of a power generation operating point control circuit device according to the present invention, in which an additional capacitor and a switching element are provided between stages of a multi-stage buck-boost chopper circuit. This is an example provided. 2A, 2B, and 2C are diagrams showing the flow of current when each switching element is in the OFF state in the circuit configuration of FIG. 1A. Dotted arrows indicate the direction of current flow. FIG. 3 is a circuit configuration diagram showing a state in which two circuit configurations (units) as shown in FIG. 1A are connected in parallel. FIG. 4 (A) is a circuit configuration diagram of the power generation operating point control circuit device according to the present invention shown in FIG. 1 (A), in which solar cells are replaced with rechargeable battery cells connected in series. FIG. 4B is a circuit configuration diagram in the case where, in the power generation operating point control circuit device according to the present invention in FIG. 1A, the solar cells are replaced and the storage cells are connected in series. FIG. 5 (A) is a circuit of the power generation operating point control circuit device according to the present invention shown in FIG. 1 (A), in which a solar cell is replaced with a fuel cell and a thermoelectric element (thermoelectric power generation) connected in series. It is a block diagram. FIG. 5 (B) is a circuit configuration diagram of the power generation operating point control circuit device according to the present invention shown in FIG. 1 (A), in which a fuel cell is replaced with a fuel cell and a generator is connected in series. .. Similar to FIG. 3, FIG. 6 is a circuit configuration diagram showing a state in which two circuit configurations (units) shown in FIG. 1 (A) are connected in parallel. It is a circuit block diagram when it replaces with a battery cell and the rechargeable battery cell is connected in series. FIG. 7A is a characteristic diagram schematically showing changes in the generated current and the generated power with respect to the generated voltage of the solar cell. FIG. 7B is a diagram showing an example of a circuit configuration of a power generation operating point control circuit device in the conventional technique. FIG. 7C is a diagram showing an exemplary time chart of ON / OFF states of the switching elements in the circuit of FIG. 7B.

PV1 to PV6 ... Solar cells M1 to M7 ... Switching element (MOSFET)
C1 to C7 ... Capacitors L1 to L6 ... Inductors S1 to S7 ... Control input ct ... Electrode connection terminals Bt1 to Bt6 ... Rechargeable battery (chemical battery) cells Cond1 to Cond2 ... Condenser cells

  The present invention will be described in detail below with reference to the accompanying drawings with reference to some preferred embodiments. In the drawings, the same reference numerals indicate the same parts.

Configuration of Operating Point Control Circuit Device The circuit configuration of the photovoltaic power generation operating point control circuit device according to the present invention is basically the configuration of a multi-stage buck-boost chopper circuit described in Non-Patent Documents 1 to 3. Is the same as. Specifically, with reference to FIG. 1A, for example, when two solar cells PV1 and PV2 are connected in series, they are connected in series between a pair of output terminals ot + and ot−. The capacitors C1 and C2 and the switching elements M1 and M2 are connected in parallel to each of the formed plurality of solar cells PV1 and PV2 (via the electrode connection terminal ct), and the solar cells PV1 and PV2 are connected. Inductors L1 and L2 are inserted between the respective electrode terminals ct and the terminals of the switching elements M1 and M2. However, in the case of the circuit configuration of the present invention, in addition to the above circuit configuration, a capacitor C3 is added in series with the capacitor array between the solar cell array and the output terminal ot-, and switching is performed. The switching element M3 is added to the element array. In such a circuit configuration, a circuit consisting of a set of solar cells, capacitors, inductors, and switching elements constitutes a single-stage chopper circuit, so to put it briefly, there are n circuits of the present invention. In the case of connecting the solar battery cells of 3 in series, it can be said that the structure includes an n + 1-stage chopper circuit, and one of the solar cells is not arranged (thus, for example, three solar cells are arranged). If the solar cells are connected in series, a four-stage chopper circuit will be used.) The additional capacitor C3 and the switching element M3 may be provided between the stages of the solar cells PV1 and PV2 as shown in FIG. 1 (C). The circuit with the switching element may be provided in a plurality of groups (that is, when n solar cells are connected in series, an n + m stage chopper circuit (m is a positive integer) is used. It may be done.) It should be understood that such a case is also included in the scope of the present invention.

  In the above configuration, the switching elements M1, M2, M3 may typically be switching elements such as MOSFETs used in a normal power generation operating point control circuit device for solar cells. The switching elements M1, M2, M3 have control inputs S1, S2, S3, respectively, and in a manner described later, between the upper and lower terminals in the figure, depending on the inputs of the control inputs S1, S2, S3. That is, the terminals at both ends of the corresponding solar cells (PV1, PV2) and the capacitors (C1, C2, C3) connected in parallel are selectively conducted or cut off. The capacitor and inductor may be any of those commonly used in the field.

  When the power generation operating point control circuit device is actually used, a load, for example, an arbitrary machine / appliance, device, charger, or the like is connected between the output terminals ot + and ot−, and output is generated. An MPPT control circuit or any other voltage / current controller that controls the voltage Vout across the terminals is connected. The voltage / current controller holds the output voltage between the output terminals at a voltage required or a desired voltage in the load, and further selectively adjusts the generated voltage of each of the solar cells PV1 and PV2. Is configured to provide a control signal to the control inputs S1, S2, S3 for conducting or interrupting. The MPPT control circuit or any other voltage / current controller may be any type of configured circuit or controller known in the field of solar cell power generation control. The load may also be connected via an MPPT control circuit or any other voltage / current controller.

Operation of Operating Point Control Circuit Device In the operation of the power generation operating point control circuit device to which the present invention is applied, basically, as already mentioned, the output terminal ot + is activated by the operation of the voltage / current controller. The output voltage Vout between the output terminals / ot- is maintained, and the conduction state of the switching element [conduction (ON) is adjusted to adjust the power generation voltage (V1, V2) of the solar cells (PV1, PV2) connected between the output terminals. ) / Interruption (OFF)] is controlled. As will be described later, such a device is a so-called multi-stage boost chopper circuit, and the height of the generated voltage of each photovoltaic cell changes the ratio of the time width of the ON / OFF state to the switching cycle of the switching element. The solar cell has a characteristic that the generated power changes depending on the generated voltage, and there is a maximum power point, so that it is possible to effectively use the power generation capacity of each solar cell. In that case, the output voltage between the output terminals has to be substantially matched with the sum of the generated voltage at the maximum power point of each solar cell. In that case, if the voltage required by the load is higher than the output voltage between the output terminals, that is, the sum of the generated voltage at the maximum power point of the solar cell, it is necessary to use a booster separately. Becomes

  In this regard, the inventors of the present invention, in the circuit configuration of the power generation operating point control circuit device described above, connect a capacitor and a switching element in parallel as described with reference to FIG. In other words, when the n solar cells are connected in series, the circuit configuration of the power generation operating point control circuit device is an n + 1-stage buck-boost chopper circuit. For the first stage, simply by not connecting the solar cells, all the solar cells generate power at the maximum power point, and the output voltage between the output terminals is at the maximum power point of the solar cells. It has been found that it is possible to make it higher than the sum of the generated voltage. The control principle and operation of the power generation operating point control circuit device will be described below.

(1) Principle of power generation voltage control of power generation operating point control circuit device (Non-Patent Documents 1 to 3) As already mentioned with reference to FIG. 7A, a solar cell generally has a power generation voltage as illustrated. On the other hand, it has a characteristic that the current (solid line) changes, and there is a maximum power point (Pm1, Pm2) at which the power becomes maximum in the change of the generated power (dashed line). The current-voltage characteristics and power-voltage characteristics of such a solar cell change depending on the environmental conditions of the solar cell, and when the amount of received light decreases due to shadows, for example, the characteristic curve shown by the current H in the figure A phenomenon occurs in which the characteristic curve indicated by the current L changes in the direction in which the current decreases, and therefore the characteristic curve indicated by the power H also changes to the characteristic curve indicated by the power L. ..

  When the solar cells having the current-voltage characteristics as described above are connected in series, for example, due to factors such as some of the solar cells entering the shade, a current-voltage characteristic curve between the solar cells If a deviation occurs, the current at the maximum power point will have a difference.Therefore, in the case of a configuration in which the same current flows through the solar cells connected in series, some solar cells will not have the maximum power point. Will not be able to generate electricity. Then, the electric power obtained in that state will be lower than the maximum electric power that should be obtained corresponding to the amount of light received by all the solar cells. Therefore, as shown in FIG. 7 (B), a power generation operating point control in which a boost chopper circuit is connected to each solar cell so that all the solar cells can generate power at their respective maximum power points. A circuit device is used, in which the generated voltage and the current are adjusted for each solar cell (Non-Patent Documents 1-3).

In the operation of the power generation operating point control circuit device, referring to FIG. 7B, first, the voltages across the solar cells PV1 and PV2 connected in series, that is, the power generation operating point control circuit device The output voltage is adjusted by the load and the MPPT control circuit and the like, and the generated voltages V1 and V2 of the solar cells PV1 and PV2 are in the ON state and the OFF state of the switching elements M1 and M2, that is, in the conduction state and the cutoff state. It is determined by the ratio of time widths. Then, as illustrated in FIG. 7C, the switching elements M1 and M2 are switched between an ON state and an OFF state at a predetermined cycle Ts, and one of them is in an OFF state. Other than the above are controlled to be in the ON state. In that case, in the step-up chopper circuit as shown in the figure, between the voltages V1 and V2 of the solar battery cell and the output voltage Vout, there is a ratio of the time width of the OFF state to the predetermined cycle Ts of the switching element. The following relationship is established using the OFF time duty ratios D1 and D2 (hereinafter, simply referred to as “duty ratio”).
Vout = V1 + V2 (1a)
V1 = D1 · Vout (1b)
V2 = D2 · Vout (1c)
That is, D1 + D2 = 1.
It should be understood that the values of Vout, D1, and D2 can be set arbitrarily within the allowable limit of each element.

Thus, in the illustrated circuit, when the output voltage Vout is equal to the sum of the generated voltage at the maximum power point of all the solar cells, that is,
Vout = V1_pm + V2_pm (2a)
(V1_pm and V2_pm are the generated voltage at the maximum power point of the solar cell, respectively), the duty ratios D1 and D2 are D1 = V1_pm / Vout (2b)
D2 = V2_pm / Vout (2c)
If adjusted so that all solar cells will generate power at the power generation voltage at the maximum power point, the maximum power that should be obtained corresponding to the amount of light received by all solar cells. Will be obtained. In the above circuit, in the actual setting of the values of Vout, D1 and D2, the MPPT control circuit monitors the voltage and current between the output terminals while changing Vout, D1 and D2. , The generated power is measured, and the conditions of Vout, D1 and D2 that give the maximum power are determined and used.

By the way, when the output voltage Vout is larger than the sum of the power generation voltages at the maximum power points of all the solar cells (which can be set by adjusting the load and the MPPT control circuit), that is, ,
Vout = V1_pm + V2_pm + ΔV (3a)
Since the expressions (1a) to (1c) are satisfied even when, the expression (2b) is satisfied, that is,
V1 = V1_pm = D1 · Vout (3b)
When is satisfied, V2 is
V2 = V2_pm + ΔV = D2 · Vout (3c)
Is decided. That is, in this case, the power generation voltage of the photovoltaic cell PV2 deviates from the power generation voltage V2_pm at the maximum power point. Then, for example, as understood with reference to the characteristic curve power L of FIG. 7 (A), the generated power of the solar battery cell PV2 decreases with the deviation ΔV of V2 as compared with the case of the maximum power point. (The operating point changes from the position of the black point to the position of the white point). That is, as in FIG. 7 (B), is at the configuration in which all the solar cell of the step-up chopper circuit is connected, in the maximum power point of the required output voltage of all of the solar cell power generation When the total voltage is higher than the sum of the voltages, all the solar cells are generated at the maximum power point to obtain the maximum power corresponding to the amount of received light. In order to obtain the maximum power, a booster is separately provided between the output terminals ot + and ot-. It is necessary to charge.

(2) Improvement of power generation voltage control of power generation operating point control circuit device according to the present invention On the other hand, in the present invention, as described above, in the circuit configuration of the power generation operating point control circuit device, a capacitor and a switching element are used. the addition of elements, an output voltage that is required even when greater than the sum of the in the power generation voltage to the maximum power point of all of the solar cells were generated all the solar cell at the maximum power point The state becomes feasible.

Specifically, referring to FIG. 1 (A) again, the circuit configuration of the power generation operating point control circuit device according to the present invention is such that a solar cell is connected to the multi-stage boost chopper circuit of FIG. 7 (B). This is a configuration in which one stage that has not been added is added. In such a configuration, in the stage to which the solar cell is not connected, there is no element having power generation capability by itself, but the capacitor C3 can accumulate charge and hold the voltage. If a difference occurs between the output voltage Vout and the voltage (V1 + V2) of the stage to which the solar cell is connected, the difference voltage is held. Thus, in the configuration of FIG. 1 (A), one switching element is added, so that the switching elements M1, M2, M3 have a predetermined cycle Ts as illustrated in FIG. 1 (B). Then, the ON state and the OFF state are switched, and one of them is controlled to be in the OFF state and the other is controlled to be in the ON state. In that case, in the step-up chopper circuit shown in the figure, the duty ratios D1, D2, D3 of the switching elements are used between the voltages V1, V2, V3 of the respective stages of the step-up chopper circuit and the output voltage Vout. Then, the following relationship is established.
Vout = V1 + V2 + V3 (4a)
V1 = D1 · Vout (4b)
V2 = D2 · Vout (4c)
V3 = D3 · Vout (4d)
That is, D1 + D2 + D3 = 1 (4e)
Becomes

Also in the case of the above circuit, the values of Vout, D1, D2, and D3 can be arbitrarily set within the allowable limit of each element, and the formulas (4a) to (4d) are always established. Therefore, first, when the output voltage Vout is equal to the sum of the generated voltage at the maximum power point of all the solar cells, that is,
Vout = V1_pm + V2_pm (5a)
, The duty ratios D1, D2, D3 are D1 = V1_pm / Vout (5b)
D2 = V2_pm / Vout (5c)
D3 = 0 / Vout (5d)
When adjusted so that all the solar cells will generate power at the power generation voltage at the maximum power point. Furthermore, when the output voltage Vout is set to be larger than the sum of the generated voltage at the maximum power point of all the solar cells, that is,
Vout = V1_pm + V2_pm + ΔV (6a)
, The duty ratios D1 and D2 can be arbitrarily set within the range that satisfies the expression (4e), so that D1, D2, and D3 are set to D1 = V1_pm / Vout (5b).
D2 = V2_pm / Vout (5c)
D3 = ΔV / Vout (5d)
It becomes possible to adjust so that. That is, as already described, in the case of the circuit configuration of FIG. 1 (A), it becomes possible to hold ΔV in the capacitor C3, and therefore, as shown in equations (5b) and (5c), It becomes possible to realize a state in which the power generation is executed at the power generation voltage at the maximum power point.

  The electric charge for the capacitor C3 to hold ΔV is given by the inflow of current from the inductor during the change process of the ON / OFF state of the switching element. Referring to FIG. 2, in the current flow during the operation of the switching element, in the capacitor C3, when the corresponding switching element is in the ON state, the current flows from the inductor of the other stage and the corresponding switch When the element is in the OFF state, current will flow from the capacitor C3. At that time, since the output voltage is held at Vout, the voltage of the capacitor C3 is the voltage obtained by subtracting the sum of the photovoltaic cell generated voltages from the output voltage Vout in the time average.

Thus, in the power generation operating point control circuit device according to the present invention, when the output voltage Vout is larger than the sum of the power generation voltages at the maximum power points of all the solar cells, the difference voltage is the capacitor. to be retained by C3, as described above, when the output voltage required is greater than the sum of the maximum in the generated voltage to the power point of all the solar cells also all the solar cell at the maximum power point It is possible to realize a state in which power is generated, and thus it is possible to generate power at all solar cells at the maximum power point and obtain maximum power corresponding to the amount of received light. In the above circuit, when actually setting the values of D1, D2, and D3, the values of D1, D2, and D3 are changed while the MPPT control circuit holds Vout of an arbitrary value. However, the voltage and current between the output terminals are monitored, the generated power is measured, and the conditions of D1, D2, and D3 that give the maximum power are determined and used.

Parallel Connection of Power Generation Operating Point Control Circuit Device According to the Present Invention The power generation operating point control circuit device according to the present invention described above has two or more units U1 and U2 at their output terminals, as illustrated in FIG. It may be used in a state of being connected in parallel. In such a configuration of parallel connection, it is necessary to make the output voltages of the units U1 and U2 equal to each other. However, in the case of the power generation operating point control circuit device according to the present invention, the output voltage of the units is as described above. Since it can be arbitrarily set, it is advantageous in that it is not necessary to separately prepare a boosting voltage unit for matching the output voltages of the units U1 and U2.

Application of the power generation operating point control circuit device according to the present invention to other power supply elements The configuration of the power generation operating point control circuit device according to the present invention is as shown in FIGS. 4 and 5 in addition to the solar cell. Chemical battery cells, power storage cells, fuel battery cells (may be solid oxide fuel cells), thermoelectric power generation elements, generator cells (wind power, water power, tidal power, any generator such as engine, , Etc.) may be applied when an arbitrary power supply cell is connected in series. When the optimum operating voltage of each power supply cell connected in series is different, the circuit configuration according to the present invention can be used to operate each cell at the optimum operating voltage. Further, the configuration of the power generation operating point control circuit device according to the present invention may be applied when the types of power supplies connected in series are different. For example, in a configuration in which a plurality of units having a circuit configuration according to the present invention as illustrated in FIG. 3 are connected in parallel, as illustrated in FIG. , Units in which solar cells are connected in series and units in which rechargeable battery (chemical battery) cells are connected in series) may be used in parallel.

  Further, in a configuration in which a plurality of units whose power supply cells connected in series are different from each other are connected in parallel, switching elements S8, S9, S10 are appropriately provided at the output terminals of each unit, as illustrated in FIG. May be. In the case of FIG. 6, the rechargeable battery can be appropriately charged with the electric power generated by the solar battery.

For example, in the operation of the illustrated example, various operating modes as described below are realized depending on the ON / OFF states of the switching elements S8, S9 and S10.
(A) When S8 = ON, S9 = ON, S10 = OFF Mode for charging the rechargeable battery with the power generated by the solar cell (b) When S8 = ON, S9 = ON, S10 = ON Mode in which surplus power is charged to the rechargeable battery while outputting power (c) When S8 = OFF, S9 = ON, S10 = ON Mode in which only rechargeable battery power is output (d) S8 = ON, S9 = When OFF, S10 = ON Mode in which only the electric power of the solar cell is output According to this configuration, energy can be appropriately transferred between the solar cell and other power sources, so that the system can output electric power in an energy-efficient state. Becomes For example, when applied to an electric vehicle (EV) equipped with a solar cell, it travels using both the electric power generated by the solar cell and the rechargeable battery while traveling, and does not output the electric power generated by the solar cell during parking. A configuration such as storing electricity in a rechargeable battery is realized.

  The advantage of the above series of operations is that in the power generation operating point control circuit device according to the present invention, the output voltage is the sum of the voltages when all the solar cells or other power supply cells operate optimally. Even if it is larger, the maximum power that can be obtained from those solar cells or other power supply cells can be used without using a booster or the like.

  Although the above description is made in connection with the embodiments of the present invention, many modifications and changes can be easily made by those skilled in the art, and the present invention is limited to the embodiments illustrated above. It will be apparent that the present invention is not limited but applies to various devices without departing from the inventive concept.

Claims (8)

A power generation operating point control circuit device for a plurality of solar cells connected in series, comprising:
A pair of output terminals,
A plurality of electrode connection terminals connected to each electrode terminal of the plurality of solar cells connected in series between the pair of output terminals,
Between the pair of output terminals, for each of the plurality of solar cells, a capacitor connected in parallel via the corresponding electrode connection terminal,
Between the pair of output terminals, for each of the plurality of solar cells, are connected in parallel via the corresponding electrode connection terminals and inductors, and for the pair of connected electrodes. And a switching means for selectively conducting between the connection terminals,
Further, between the pair of output terminals, between the electrode connection terminal and one of the output terminals on one end side of the plurality of solar cells connected in series, or the plurality of series connected. An additional capacitor is connected in series with the capacitor between the two electrode connection terminals between two adjacent solar cells of the solar cell of In parallel and in series with the switching means additional switching means is connected , solar cells are not connected in parallel to the additional capacitor and the additional switching means,
The switching means and the additional switching means are in the same predetermined cycle and at different times, respectively, between the connected pair of electrode connection terminals, and the connected electrode connection terminal and the output. The connection between one of the terminals and the corresponding terminal of the two electrode connection terminals is interrupted, and one of the switching means and the additional switching means is always connected to the connection. The connection between the corresponding electrode connection terminals, between the connected electrode connection terminal and one of the output terminals, and between the corresponding terminals of the two electrode connection terminals. , The other switching means and the additional switching means, between the connected pair of electrode connection terminals, between the connected electrode connection terminal and one of the output terminals, and for the two electrodes A device in which the conduction of the switching means and the additional switching means is controlled so as to conduct between corresponding terminals of the connection terminals.   2. The device according to claim 1, wherein a ratio of a time width for interrupting conduction between the pair of connected electrode connection terminals for the predetermined period of each of the switching means is between the pair of output terminals. It is the ratio of the generated voltage of the corresponding solar cells of each of the switching means to the output voltage, the output voltage between the pair of output terminals is higher than the sum of the generated voltage of the solar cells connected in series. When it is a voltage, a time width for interrupting conduction between the connected electrode connection terminal and one of the output terminals or between the two electrode connection terminals for the predetermined cycle of the additional switching means. Is the ratio of the voltage difference obtained by subtracting the sum of the generated voltage of the photovoltaic cells from the output voltage between the pair of output terminals with respect to the output voltage between the pair of output terminals.   3. The device according to claim 2, wherein the output voltage between the pair of output terminals is a desired voltage, and conduction between the pair of connected electrode connection terminals for the predetermined period of the switching means is established. A device in which the ratio of the time widths of interruption is adjusted so that the generated voltage of the corresponding solar battery cell becomes the voltage at the maximum operating point.   4. The apparatus according to claim 3, wherein the pair of connected switching means for each of the predetermined cycles of each of the switching means is such that a generated voltage of the solar cells connected in series becomes a voltage at the maximum operating point. The device further comprising means for adjusting a ratio of time widths for interrupting conduction between the electrode connection terminals.   An apparatus in which a pair of output terminals of a plurality of the apparatus according to any one of claims 1 to 4 are connected in parallel with each other.   The device according to claim 1, wherein at least a part of the solar battery cells is replaced with a chemical battery cell or a battery cell.   An apparatus in which a pair of output terminals of a plurality of the apparatus of claim 6 are connected in parallel with each other. An operating point control circuit device for a plurality of power supply cells connected in series,
A pair of output terminals,
A plurality of electrode connection terminals connected to each electrode terminal of the plurality of power supply cells connected in series between the pair of output terminals,
Between the pair of output terminals, for each of the plurality of power supply cells, a capacitor connected in parallel via the corresponding electrode connection terminal,
Between the pair of output terminals, each of the plurality of power supply cells is connected in parallel via the corresponding electrode connection terminal and the inductor, and the pair of connected electrode connections is connected. And a switching means for selectively conducting between the terminals,
Further, between the pair of output terminals, between the electrode connection terminal on one end side of the plurality of power supply cells connected in series and one of the output terminals, or the plurality of series-connected output terminals. An additional capacitor is connected in series to the capacitor between two connection terminals for the electrodes between two adjacent power cells of the power cells, and the additional capacitor is connected in parallel to the additional capacitor. And the additional switching means is connected in series to the switching means, the power supply cell is not connected in parallel to the additional capacitor and the additional switching means,
The switching means and the additional switching means are in the same predetermined cycle and at different times, respectively, between the connected pair of electrode connection terminals, and the connected electrode connection terminal and the output. The connection between one of the terminals and the corresponding terminal of the two electrode connection terminals is interrupted, and one of the switching means and the additional switching means is always connected to the connection. The connection between the corresponding electrode connection terminals, between the connected electrode connection terminal and one of the output terminals, and between the corresponding terminals of the two electrode connection terminals. , The other switching means and the additional switching means, between the connected pair of electrode connection terminals, between the connected electrode connection terminal and one of the output terminals, and for the two electrodes A device in which the conduction of the switching means and the additional switching means is controlled so as to conduct between corresponding terminals of the connection terminals.

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