JP6511686B2 - Converter, converter system for solar cell module, and converter system for storage module - Google Patents

Description

  According to the present invention, in a solar cell string (solar cell module chain) configured by series connection of a plurality of solar cell modules, output control of the solar cell module can be performed while preventing various adverse effects due to partial shadows. The present invention relates to an integrated converter which integrates a converter and a partial shadow compensator, and an integrated converter and an integrated converter system which operate according to the same principle.

  A solar cell typically has a structure in which a p-type semiconductor and an n-type semiconductor are bonded and an electrode or the like is attached, and converts light energy such as sunlight into an electromotive force. In order to make the best use of solar energy in a solar power system using solar cells, it is necessary to operate the solar cell module at the maximum power point (MPP) using a power conditioner or the like. . In general, the electrical characteristics of the solar cell module largely depend on the amount of solar radiation, and in the state where shadows occur, the current that can be generated is greatly reduced.

  When connecting a plurality of modules in series to configure and use a solar cell string, the effect of "partial shadows" that cause some modules to be shadowed is that the power that can be generated as a whole string is greatly reduced It has been known. FIG. 1 shows the current paths in the string in the partially shaded situation of some modules (PV1), as well as the electrical characteristics of each module. The diodes connected in parallel with each module are bypass diodes to prevent the modules from being reverse biased. The shaded module (hereinafter referred to as a shadow module) has a smaller current that can be generated compared to a non-shadowed module (hereinafter referred to as a sunshine module), and an imbalance occurs in each module characteristic.

  In this case, if a current larger than the current that can be supplied to the shadow module flows in the string, the bypass diode connected to the shadow module becomes conductive as shown, and the shadow module is bypassed. At this time, the voltage of the shadow module is equal to the voltage of the bypass diode, that is, approximately 0V. Although the shadow module is inherently capable of generating some power, the conduction of the bypass diode renders the shadow module incapable of generating power, so the power that can be generated as a string is greatly reduced.

  An example of the electrical characteristics of the entire string when partial shadowing occurs is shown in FIG. By bypassing the shadow module, the voltage-current (VI) characteristic becomes a step-like characteristic, and a plurality of MPPs are generated on the voltage-power (VP) characteristic of the string (B in FIG. 2). Point and point C). In this case, the power conditioner may cause the string to operate at a non-optimum point (point C in FIG. 1) different from the true MPP (point B in FIG. 2).

JP, 2012-028435, A Unexamined-Japanese-Patent No. 2004-047585 JP, 2013-105318, A JP 2011-228598 A

T. Shimizu, O, Hashimoto, and G. Kimura, “A novel high-performance utility-interactive photovoltaic inverter system,” IEEE Trans. Power Electron., Vol. 18, No. 2, pp. 704-711, Mar. 2003. T. Shimizu, M. Hirakata, T. Kamezawa, and H. Watanabe, "Generation control circuit for photovoltaic modules," IEEE Trans. Power Electron., Vol. 16, No. 3, pp. 293-300, May 2001. S. Qin and R. C. N. Pilawa-Podgurski, "Sub-module differential power processing for photovoltaic applications," IEEE Applied Power Electron. Conf. Expo., Pp. 101-108, 2013. JT Stauth, MD Seeman, and K. Kesarwani, “Resonant switched-capacitor converters for sub-module distributed photovoltaic power management,” IEEE Trans. Power Electron., Vol. 28, No. 3, pp. 1189-1198, Mar. 2013.

  As means for eliminating or reducing these adverse effects due to partial shadows, individual control of each module by a microconverter / inverter, development of control to which a true MPP search algorithm using operating point scanning is added, and the like have been performed. However, in the micro-converter / inverter system, a power converter is required for each module, which tends to increase the cost of the system (FIG. 3). On the other hand, MPP search algorithms using operating point scanning still have major issues such as complicated control, reduced responsiveness, and reduced power extraction rate. A large number of other solutions have also been proposed, but the cost may increase due to the need for computations and information detection systems based on a huge amount of data.

  In addition, various partial shadow compensators have been proposed which prevent characteristic degradation due to partial shadows. A conceptual diagram of a solar cell system using a partial shadow compensator is shown in FIG. In a system using a partial shadow compensator, it is possible to equalize the electrical characteristics of all modules in a pseudo manner by transmitting a part of the generated power of the sunlight module to the shadow module, so the micro-inverter can be used even during partial shadow generation The solar cell string can be operated by MPP with a general purpose power conditioner without using an MPP search algorithm or the like. Various circuit schemes have been proposed as partial shadow compensators. As a typical circuit thereof, FIG. 5 shows a system using a switched capacitor.

  In the switched capacitor of FIG. 5, the capacitors Cin1 to Cin3 and Ca and Cb mutually charge and discharge by high-speed switching of the switches Q1 to Q6, whereby the voltage shared by each capacitor becomes uniform.

  Specifically, when the odd-numbered switches Q1, Q3 and Q5 are on, the capacitors Cin1 and Ca and the capacitors Cin2 and Cb are connected in parallel, respectively. When variation in voltage occurs, mutual charging and discharging are performed, and the voltage variation is eliminated. On the other hand, when the even-numbered switches Q2, Q4 and Q6 are on, the capacitors Cin2 and Ca and the capacitors Cin3 and Cb are respectively connected in parallel. In the case of the occurrence of the variation of (1), the mutual charging and discharging are performed, and the voltage variation is resolved.

  Therefore, by repeating switching between the state in which all the odd numbered switches are turned on and the state in which all the even numbered switches are turned on, each capacitor is directly or indirectly connected to all the other capacitors. The mutual charge and discharge are performed (through other capacitors), so that the voltages of the capacitors Cin1 to Cin3 and Ca and Cb are equalized. At this time, the voltage applied to the solar cell modules (arbitrary modules configured of one or more solar cells and operable as a solar cell) connected in parallel to each of the capacitors Cin1 to Cin3 are also equalized. Be done. In the case of a "partial shadow" state in which some of the solar cell modules are shaded, it may not be possible to generate a current corresponding to the applied voltage from the shadow module, but the capacitors Cin1 to Cin3 Because current is supplied from the other solar cell module to the shadow module (the voltage of the shadow module is usually lower than the voltage of the sunshine module, the current through the capacitors Cin1 to Cin3 is preferentially given to the shadow module). In fact, a current corresponding to the applied voltage will flow out of the shadow module as well, which makes it possible to perform an operation in which the influence of the partial shadow is compensated. The smoothing capacitors Cin1 to Cin3 may be omitted. Also in this case, all the solar cell modules PV1 to PV3 and the capacitors Ca and Cb can be directly or indirectly (self-operated (self) by repeating switching to turn on even-numbered switches and odd-numbered switches alternately. And the voltages applied to the solar cell modules PV1 to PV3 and the voltages of the capacitors Ca and Cb are equalized, and shadows from other solar cell modules via the capacitors Ca and Cb are obtained. Since current is supplied to the module (the voltage of the shadow module is usually lower than the voltage of the sunlight module, the current through the capacitors Ca and Cb preferentially flows into the shadow module), so the shadow module also simulates In fact, a current corresponding to the applied voltage flows out, and an operation in which the influence of the partial shadow is compensated is possible. It is general to operate the switching capacitor of FIG. 5 with a ratio (time ratio) of an odd number switch ON period or an even number switch ON period (time ratio) to one cycle of switching. However, even at a duty ratio other than 50%, it is possible to equalize the voltage of each solar cell module to compensate for the influence of the partial shadow. The above operation is the same as in the case where the number of solar cell modules in series is other than 3 (arbitrary number of 2 or more). Also, the capacitance of each capacitor may be different.

  Although the use of a partial shadow compensator can prevent the adverse effect of partial shadows, as shown in FIG. 4, in addition to the converter that controls the entire string, a partial shadow compensator is required, resulting in a complicated overall system configuration. Become.

  In view of the above, it is an object of the present invention to provide a converter whose system configuration is simplified by reducing the total number of switches, and a converter system for a solar cell module or a storage battery module using the converter.

  In order to solve the above problems, the present invention comprises a plurality of capacitors and a plurality of switches, and repeatedly switches the plurality of switches to repeatedly switch the connection state of the capacitors included in the plurality of capacitors. Of the plurality of switches and the switch capacitor portion configured to adjust the voltage in such a direction that the charge and discharge between the plurality of capacitors are eliminated. A converter comprising: a switching converter unit configured to share a part of switches with a switched capacitor part, receive and convert an input voltage that is changed by switching of part of switches, and output as an output voltage I will provide a.

  As described above, by operating the switching converter unit with a part of the switch used for the operation of the switched capacitor unit, it is possible to unify the switched capacitor unit and the switching converter unit and reduce the total number of switches.

  The switched capacitor unit is, for example, (1) first to n (n is an integer of 2 or more) capacitors connected in series, and (2) a second i-1 (i = 1 to n) connected in series An i-th switch set comprising a switch and a 2i-th switch connected in parallel to the i-th capacitor; , (3) connected between the midpoint of two switches included in the j-th (j = 1 to n-1) switch set and the midpoint of two switches included in the j + 1th switch set Although it can be configured as a switched capacitor section including the (n + 1) th to (2n-1) th capacitors provided as jth to (n + 1) th capacitors for j from 1 to n-1, respectively, the present invention is not limited thereto. The You may use any of the switched capacitor portion operated by pitch.

  When one example of the switched capacitor unit is used, in one example, the switching converter unit shares one of the first to n-th switch pairs with the switched capacitor unit, and includes an inductor and is used as a shared switch pair. A switch that shares a state in which electromagnetic energy is stored in the inductor by current flowing through one of two included switches, and a state in which electromagnetic energy is released from the inductor by current flowing through the other of the two switches The switching converter unit can be configured to operate by switching by switching the switches in the group.

  When one example of the switched capacitor unit is used, the switching converter unit in another example shares one of the first to n-th switch pairs with the switched capacitor unit, and includes an inductor and a capacitor. The present invention can be configured as a resonant converter unit and configured to output an output voltage depending on the switching frequency of two switches included in the shared switch set.

  When using the example of the said switched capacitor part, the converter system for solar cell modules can be comprised by connecting a solar cell module in parallel with each of the 1st to nth capacitor in the converter of this invention. Alternatively, the solar cell module converter system may be configured by connecting solar cell modules instead of each of the first to nth capacitors in the converter of the present invention.

  When one example of the switched capacitor unit is used, a storage module converter system can be configured by connecting a storage module in parallel to each of the first to nth capacitors in the converter of the present invention. Alternatively, the storage module converter system may be configured by connecting storage modules instead of each of the first to nth capacitors in the converter of the present invention. Here, the storage module is an arbitrary chargeable / dischargeable module including one or more optional storage cells such as a capacitor, a secondary battery, an electric double layer capacitor, and the like.

  The present invention also includes a plurality of capacitors and a plurality of switches, and the plurality of capacitors are mutually charged and discharged by repeatedly switching the plurality of switches and repeatedly switching the connection state of the capacitors included in the plurality of capacitors. A first switched capacitor portion and a second switched capacitor portion, each configured to adjust a voltage in a direction in which a variation in voltage applied to each of the capacitors included in the plurality of capacitors is eliminated. And one end of the inductor is connected to a part of the plurality of switches included in the first switched capacitor section, and the other end of the inductor is included in the plurality of switches included in the second switched capacitor section. By connecting to a part of switches, the first switched A first switched capacitor unit that shares part of a plurality of switches with the shutter unit and the second switched capacitor unit, receives an input voltage input that changes by switching the shared switch, converts the input voltage, and performs the same frequency A converter comprising: a switching converter unit configured to output an output voltage dependent on a phase difference between switch switching in the second switching switch unit and switching switching in the second switched capacitor unit. As a converter of this invention, it is an example which converts an input voltage by the phase difference of the switch switching in two switched capacitor parts.

  In the integrated solar cell converter that can be configured according to the present invention, since a partial shadow compensator using a conventional switched capacitor and a converter such as a step-down PWM (Pulse Width Modulation) converter can be integrated, the system The configuration can be simplified. Also, in the integration, since the switched capacitor and the converter share some switches (two switches Q5 and Q6 in the example of FIG. 7 described later), the system is compared with the conventional system using the partial shadow compensator and the converter separately It is also possible to reduce the total number of switches. The converter simplified according to the invention is also applicable to any other application, such as voltage equalization between storage modules.

The figure which shows the current path in a solar cell string at the time of partial shadow generation | occurrence | production, and the electrical property of a module. Graph showing comparison of string characteristics with and without partial shadow. The conceptual diagram of the solar power generation system using a micro converter. The conceptual diagram of the solar energy power generation system using a partial shadow compensator. The circuit diagram of the partial shadow compensator which used the switched capacitor. FIG. 5 is a circuit diagram of a step-down converter that can be used as a switching converter unit in the converter of the present invention. The circuit diagram of the converter system for solar cell modules which connects a solar cell module to the integrated converter which integrated the switched capacitor and the pressure | voltage fall type PWM converter. The figure which shows the connection state of the period which the switch of the even number turns on at the time of operation | movement of a pressure | voltage fall type PWM converter. The figure which shows the connection state of the period while the switch of the odd number is ON at the time of operation | movement of a pressure | voltage fall type PWM converter. FIG. 8 is a graph showing the result of an operation experiment performed by prototyping the integrated converter according to the circuit diagram of FIG. 7. The circuit diagram of the converter system for electrical storage modules which connects an electrical storage module instead of a solar cell module in the integrated converter of FIG. FIG. 8 is a circuit diagram when the shared switch is changed from Q5 and Q6 to Q3 and Q4 in the integrated converter of FIG. 7; FIG. 8 is a circuit diagram when the shared switch is changed from Q5 and Q6 to Q1 and Q2 in the integrated converter of FIG. 7; FIG. 8 is a circuit diagram when capacitors Cin1 to Cin3 as smoothing capacitors are removed from the integrated converter of FIG. 7; FIG. 8 is a circuit diagram when the number of serial stages is changed to 2 in the integrated converter of FIG. 7; FIG. 15 is a circuit diagram when a resonant converter is used instead of the step-down PWM converter in the integrated converter of FIG. 14; The circuit diagram of the converter system for solar cell modules which connects a solar cell module to the integrated converter which integrated two switched capacitor and phase shift converter as another embodiment of the converter of this invention.

  The configuration and operation of the converter and converter system according to the present invention will now be described using the drawings. However, the configurations of the converter and converter system according to the present invention are not limited to the specific specific configurations shown in the respective drawings, and can be appropriately changed within the scope of the present invention. For example, although each capacitor is mainly described below as a single storage element, these are optional elements that can be charged and discharged, a module including one or more elements, or any device configured using these modules It may be The capacities of the respective storage elements may also be different. Although each switch is also described below as a semiconductor switch such as a MOSFET, it is also possible to use any electronic switch or mechanical switch. Besides, although the converter in the following embodiments is described as a 3-series or 2-series solar cell module chain, a 3-series stage, 2-series stage converter adapted to a storage module chain, the converter according to the present invention The number of serial stages of may be any number n of 2 or more. The load connected to the output side of the converter may also be any circuit, device or the like.

Configuration of Integrated Converter The integrated converter which is an embodiment of the present invention is obtained by integrating the switched capacitor connected to the solar cell module chain in FIG. 5 and the step-down PWM converter shown in FIG. Be

The step-down PWM converter shown in FIG. 6 includes an input power supply Vin, an input capacitor Cin, a switch Q, a diode Do, an inductor L, an output capacitor Cout, and a load RL, and the switch Q is repeatedly switched on and off. The voltage V _in is converted to the output voltage V _out . Assuming that the duty ratio in switching of switch Q (the ratio of the on period of switch Q to one cycle of switching) is D (0 ≦ D ≦ 1), the average voltage of inductor L over one cycle is zero in the steady state. Therefore, in consideration of the voltage applied to the inductor L in the on period and the off period of the switch Q, D (V _in −V _out ) + (1−D) (− V _out ) = 0
... (1)
And
V _out / V _in = D
... (2)
Is obtained.

  A specific circuit configuration of the integrated converter is shown in FIG. The integrated converter includes (1) switched capacitors including capacitors Cin1 to Cin3, C1 and C2 and switches Q1 to Q6, and (2) an inductor L, an output side capacitor Cout, and a load RL, and further includes a switch Q5, A step-down type PWM converter unit sharing Q6 with the switched capacitor unit is provided, and solar cell modules PV1 to PV3 are connected to capacitors Cin1 to Cin3 which are smoothing capacitors. In the circuit of FIG. 7, focusing only on the switched capacitor part has the same configuration as that of the circuit of FIG. 5, while focusing on the PWM converter in FIG. 7, the diode Do in FIG. 7 and the PWM converter unit in FIG. 7 have the same configuration.

Operation of the integrated converter The integrated converter of FIG. 7 has a state in which only the even-numbered switches Q2, Q4 and Q6 among the switches Q1 to Q6 are on and a state in which only the odd-numbered switches Q1, Q3 and Q5 are on Is defined as a ratio to one cycle of switch switching in a period in which only even numbered switches are turned on in this embodiment 1 as a duty ratio D, but only odd numbered switches are selected. The duty ratio may be defined as a ratio of the period to be turned on to the one cycle.) Even if partial shadows are generated in the solar cell modules PV1 to PV3, this is compensated by switching repeatedly. The solar cell module chain by adjusting the voltage applied across the chain of the solar cell module while the voltage applied to each solar cell module is uniformed It is possible to perform the output power control of the pond module chain. A conventional partial shadow compensator using a switched capacitor generally operates at a 50% duty ratio, but partial shadow compensation and voltage equalization of the solar cell module are possible even at a duty ratio other than 50%.

  Specifically, in the circuit of FIG. 7, the operation of the switched capacitor portion is the same as the operation of the switched capacitor of FIG. 5 already described. Only the even numbered switches Q2, Q4 and Q6 are on (FIG. 8a, the off switches are not shown), and only the odd numbered switches Q1, Q3 and Q5 are on (FIG. 8b, the off switches are not) Each of the capacitors Cin1 to Cin3, C1 and C2 directly or indirectly (through other capacitors) mutually charge / discharge with all the capacitors other than itself by repeatedly switching) and. The voltages of the capacitors Cin1 to Cin3, C1, and C2 are equalized. In the “partial shadow” state in which some of the solar cell modules are shaded, the current is supplied from the other solar cell modules to the shadow modules via the smoothing capacitors Cin1 to Cin3 (shadow Since the module voltage is usually lower than the voltage of the sunshine module, the current through the capacitors Cin1 to Cin3 preferentially flows into the shadow module), and the shadow module also flows a current according to the applied voltage. This makes it possible to perform an operation that compensates for the effects of partial shadows.

  Furthermore, in the circuit of FIG. 7, the PWM converter unit receives an input voltage input that changes when the switch turned on among the switch sets Q5 and Q6 is repeatedly switched by the above-described operation of the switched capacitor and converts it. Output to the load RL as an output voltage.

Switch Q6 is turned on input voltage in the period (the switch Q2 of the even number, Q4, Q6 only on), the solar cell module PV1, PV2, if the voltage PV3 and _{V PV1, V PV2, V PV3} V PV1 + V _PV2 + V is _PV3 (Figure 8a), the voltage V _L applied to the inductor L during this _{period, V L = V PV1 + V} PV2 + V PV3 -V out if the output voltage of the PWM converter and the V _out
... (3)
(The polarity of the current flowing through the inductor L from the input side to the output side of the PWM converter section is positive. The same applies to the following). During this period, electromagnetic energy is accumulated in the inductor L by the current flowing through the switch Q6.

On the other hand, the input voltage at the period of the switch Q5 is turned on (the switch Q1, Q3, Q5 only on odd-numbered) is the V _PV1 + V _PV2 (Figure 8b), the voltage V _L applied to the inductor L during the period Is
V _L = V _PV1 + V _PV2- V _out
... (4)
Is represented by During this period, electromagnetic energy is released from the inductor L by the current flowing through the switch Q5.

Since the average voltage of the inductor L over one cycle of switching is zero in the steady state, the voltage V _L of the inductor L in each of the periods obtained by the equations (3) and (4) The following equation (5) is established by multiplying and adding the ratio to the period.
D ( _VPV1 + _VPV2 + _VPV3 - _Vout ) + (1-D) ( _VPV1 + _VPV2 - _Vout ) = 0
... (5)
By solving this equation, the following equation (6) is obtained.
V _out = V _PV1 + V _PV2 + DV _PV3
... (6)

Assuming that the voltages of all the solar cell modules are uniform as V _PV1 = V _PV2 = V _PV3 = V _PV by the operation of the switched capacitor unit, the equation (6) can be rewritten as the following equation (7).
V _out = (D + 2) V _PV
... (7)
As the equations (6) and (7) indicate, the output voltage V _out depends on the duty ratio D. Therefore, if the integrated converter of the present invention is used, the power of the solar cell string is adjusted by adjusting the duty ratio D as in the conventional converter (adjusting with an arbitrary switch control circuit etc. The switch control circuit is not shown). Control is possible. In one example, when a constant voltage load is used as the load RL, the output voltage V _out has a fixed value, so from the equation (7), V _PV = V _out / (D + 2)
... (8)
Thus, the solar cell module voltage can be controlled and hence the output power of the solar cell module chain can be controlled.

Experimental results using the integrated type converter An inductor with an inductance of 15 μH as the inductor L, a capacitor with a capacitance of 47 μF as the capacitors Cin1 to Cin3 for smoothing, a capacitor with a capacitance of 33 μF as the capacitors C1 and C2, a capacitance of 141 μF as the output side capacitor Cout An integrated converter of the circuit structure shown in FIG. Next, a solar array simulator (manufactured by Agilent Technologies, E4350B) is connected as the solar cell modules PV1 to PV3 according to FIG. 7 to intentionally simulate a state in which a partial shadow is generated on both the solar cell modules PV1 and PV2 The string characteristics were scanned by manually changing the duty ratio D of the integrated converter at a load voltage of 28 V (constant voltage load).

  The power characteristics obtained at the output of the integrated converter are shown in FIG. In order to show the effect of the extraction power improvement by an integrated converter, the result of having directly connected variable resistance with respect to the solar array simulator, and scanning a string characteristic is also shown collectively, without using an integrated converter. In the case where the integrated converter is not used, two maximum power points exist on the PV (power-voltage) characteristics of the string, and the maximum extractable power is about 45 W (when the string voltage is about 24 V) there were. On the other hand, by using the integrated converter, the maximum power point converged to one point, and the extractable maximum power was also greatly increased to about 61 W (when the string voltage is about 33 V). This experiment shows that the integrated converter can significantly improve the extraction power from the solar cell under partial shadow conditions.

Storage System Converter System The converter of the present invention can be used not only as a solar cell module converter system but also as a storage system converter system as shown in the circuit diagram of FIG. 10, for example. In FIG. 10, not the solar cell modules PV1 to PV3 but the storage modules B1 to B3 are connected to the integrated converter. The operation of the integrated converter is basically similar to that described in the embodiment of FIG. By alternately turning on the even-numbered switches Q2, Q4, Q6 of the switched capacitor portion and the odd-numbered switches Q1, Q3, Q5, the voltages of the capacitors Cin1 to Cin3, C1, C2 are equalized, and the capacitors Cin1 to Cin1 are switched on. The voltages of the storage modules B1 to B3 connected in parallel to Cin3 are also equalized (the problem of partial shadows does not occur, so the compensation thereof is also unnecessary). At the same time, the PWM converter unit operates by switching between the shared switch sets Q5 and Q6. Assuming that the voltages of the storage modules B1, B2 and B3 are V _B1 , V _B2 and V _B3 respectively, the output voltage of the PWM converter (voltage of the load RL is calculated by the same calculation as the equations (3) to (7). ) V _out is V _out = V _B1 + V _B2 + DV _B3
... (9)
And if V _B1 = V _B2 = V _B3 = V _B , then V _out = (D + 2) V _B
... (10)
Is obtained.

  Although FIG. 7 shows a circuit configuration in which the switched capacitor unit and the step-down PWM converter unit share the switches Q5 and Q6, a circuit configuration in which other switches are shared is also possible. FIG. 11 shows a circuit configuration in which the switched capacitor unit and the PWM converter unit share the switches Q3 and Q4, and FIG. 12 shows a circuit configuration in which the switches Q1 and Q2 are shared. Also in these circuit configurations, it is possible to control the output power of the solar cell module chain on the same principle while preventing the adverse effect of the partial shadow.

When the integrated converter shown in FIG. 11 is used, the voltage applied to the inductor L during the on period of the even-numbered switches Q2, Q4, and Q6 is V _L = V _PV1 + V _PV2- V _out
... (11)
(Electromagnetic energy is accumulated in the inductor L by the current flowing through the switch Q4 during this period), and the voltage applied to the inductor L during the on period of the odd-numbered switches Q1, Q3 and Q5. Is V _L = V _PV1- V _out
... (12)
(During this period, electromagnetic energy is released from the inductor L by the current flowing through the switch Q3), and the average voltage of the inductor L over one cycle of switching becomes zero in the steady state. (V _PV1 + V _PV2 -V _out ) + (1-D) (V _PV1 -V _out ) = 0
... (13)
And the output voltage is V _out = V _PV1 + DV _PV2
... (14)
If V _PV1 = V _PV2 = V _PV3 = V _PV , then V _out = (D + 1) V _PV
... (15)
Is obtained.

When the integrated converter shown in FIG. 12 is used, the voltage applied to the inductor L during the on period of the even-numbered switches Q2, Q4, and Q6 is V _L = V _PV1- V _out
... (16)
(Electromagnetic energy is stored in the inductor L by the current flowing through the switch Q2 during this period), and the voltage applied to the inductor L during the on period of the odd-numbered switches Q1, Q3 and Q5. Is V _L =-V _out
... (17)
(During this period, electromagnetic energy is released from the inductor L by the current flowing through the switch Q1), the average voltage of the inductor L over one cycle of switching becomes zero in the steady state. (V _PV1 −V _out ) + (1−D) (− V _out ) = 0
... (18)
And the output voltage is V _out = DV _PV1
... (19)
If V _PV1 = V _PV2 = V _PV3 = V _PV , then V _out = DV _PV
... (20)
Is obtained.

As can be seen from the equations (7), (15) and (20), the equation of the output voltage _Vout is different depending on the shared switch. Therefore, it is necessary to select an appropriate circuit configuration (select a switch to be shared) according to the value of V _out required. The operation is basically the same when using a storage module or the like instead of the solar cell module.

  As already described in connection with the switched capacitor of FIG. 5, the smoothing capacitors Cin1 to Cin3 may be omitted in all the integrated converters shown in FIGS. 7 to 12 (an example is shown in FIG. 13). Show). Also in this case, all solar cell modules PV1 to PV3 (or storage modules B1 to B3 or the like) and the capacitors C1 and C2 and the capacitors C1 and C2 are repeatedly switched by alternately turning on even numbered switches and odd numbered switches. Are connected directly or indirectly (via other than self), so that the voltages applied to the solar cell modules PV1 to PV3 (or storage modules B1 to B3 etc.) and the voltages of the capacitors C1 and C2 are equalized. When the solar cell modules PV1 to PV3 are connected, current is supplied from the other solar cell module to the shadow module through the capacitors C1 and C2 (the voltage of the shadow module is usually Because the voltage is lower than the module voltage, the current through capacitors C1 and C2 preferentially flows to the shadow module No.), Current will be flow out in accordance with the applied voltage to pseudo from shadow module, thereby enabling operation to compensate for the effects of partial shade.

  Similarly, as already described above, the number of series of integrated converters is not limited to 3 but is arbitrary as long as it is 2 or more. For example, the integrated converter shown in FIG. It can be mentioned.

  The specific configurations of the switched capacitor unit and the switching converter unit used in the integrated converter according to the present invention are not limited to the configurations described in the first embodiment, and are arbitrary. Fig. 15 shows an example of the circuit configuration of an integrated converter using a resonant converter instead of a step-down type PWM converter as a switching converter, a switched capacitor unit consisting of two switched capacitors, and a phase shift converter as a switching converter FIG. 16 shows an example of the circuit configuration in which the unit is configured.

  In the integrated converter of FIG. 15, the switched capacitor portion is the same as that used in the first embodiment (although the number of serial stages is two but arbitrary, C4 to C6 represent capacitors and Q5 to Q8 represent switches). As a switching converter unit, a primary winding side circuit sharing the switching capacitor unit and the switches Q7 and Q8 and including an inductor Lr and a capacitor Cr (Lmg represents an excitation inductance of the primary winding), and A resonance type converter unit is used, in which a transformer is configured by including a winding side circuit (Diodes D1 to D4 are for rectifying corresponding to respective polarities of secondary current changing due to resonance) Is).

  In the embodiment of FIG. 15, the odd numbered switches Q5 and Q7 and the even numbered switches Q6 and Q8 have a 50% duty ratio (also in the second embodiment, for a period during which only the even numbered switches are turned on). The ratio to one cycle of switch switching is defined as the duty ratio D, but the duty ratio may be defined as the ratio to the one cycle of the period in which only odd numbered switches are turned on. By making this operation, the voltages of the solar cell modules PV1 and PV2 are equalized according to the same principle as that already described with reference to FIG. 5 etc., and when a partial shadow occurs, this is compensated while By adjusting switching frequency of odd numbered and even numbered switches by switching frequency modulation (PFM: Pulse Frequency Modulation), load R To control the voltage. Since the switches Q7 and Q8 are alternately turned on, a rectangular wave voltage is generated at the connection point between the switches and is input to the resonant converter.

  The capacitor Cr and the inductors Lr and Lmg constitute a resonant circuit, and have gain characteristics dependent on the frequency of the input voltage. Therefore, by changing the frequency of the rectangular wave voltage input to the resonant circuit, any gain, that is, the output voltage (The voltage of the load RL) can be obtained. That is, although the duty ratio of the switch is fixed at 50%, the load voltage is controlled by changing the switching frequency.

  Although the so-called LLC type resonant converter unit is used in the integrated converter of FIG. 15, a wide variety of other resonant converter units can be considered, and the integrated type is based on the same principle regardless of which system is used. The converter can be operated. Further, although an example using an insulating resonant converter using a transformer has been described here, it is possible to operate the integrated converter according to the same principle even using a non-insulating resonant converter using no transformer. it can.

  Further, in the integrated converter of FIG. 16, the switched capacitor unit is composed of the switched capacitor unit 1 and the switched capacitor unit 2 (the number of series stages is 2, although it is arbitrary. The number of series stages is different between the switched capacitor sections 1 and 2) C1 to C6 represent capacitors and Q1 to Q8 represent switches.) The switching converter unit shares the switch capacitor unit 1 with the switches Q7 and Q8, and the switched capacitor unit 2 and the switch Q3, It is configured as a phase shift converter unit sharing Q4.

  Also in the embodiment of FIG. 16, the odd numbered switches Q1 and Q3 and the even numbered switches Q2 and Q4 have a 50% duty ratio (even numbered even for convenience. Although the ratio to one cycle of switch switching is defined as duty ratio D in a period in which only the switch is turned on, it is also possible to define the duty ratio as a ratio to one cycle in a period in which only odd numbered switches are turned on. And the odd-numbered switches Q5 and Q7 and the even-numbered switches Q6 and Q8 are also alternately turned on at a 50% duty ratio. Thereby, the voltages of the capacitors and the solar cell modules included in each switched capacitor unit are equalized to one another. However, in the embodiment of FIG. 16, the switching frequency of the switched capacitor units 1 and 2 is the same, but a phase difference is provided between the timings, and this phase difference is adjusted (phase shift control) Control the voltage of the load RL).

  Since the switch set of switches Q7 and Q8 and the switch set of switches Q3 and Q4 operate alternately with a phase difference, a rectangular wave voltage is generated at the connection point between the switches in each switch set, and the phase is changed. The voltage is applied to the inductor L in the shift converter unit. Since the power transmitted through the inductor L depends on the phase difference between the two rectangular wave voltages applied across the inductor L, the transmitted power can be controlled by appropriately varying the phase difference, ie, The load voltage can be controlled. That is, in this embodiment, the voltages of PV1 and PV2 are equalized by the switched capacitor unit 1, and if a partial shadow is generated, this is compensated while phase shift control between the switched capacitor units 1 and 2 is performed. Controls the load voltage.

  The integrated converter shown in FIGS. 15 and 16 can also be connected to a storage module or the like instead of the solar cell module and operated on the same principle, and the capacitors C4 and C5 for smoothing may be omitted. . In addition, any optionality of the specific embodiments described in connection with Example 1 is also true in Example 2.

  INDUSTRIAL APPLICABILITY The present invention can be widely applied to a power supply that constitutes a string by connecting in series any module consisting of one or more elements, such as a solar cell module, a storage module, and the like.

PV1 to PV4, PVn Solar cell modules Q1 to Q8, Q switches L, Lr, Lmg Inductor (inductance)
C1 to C5, Cin1 to Cin3, Ca, Cb, Cin, Cout, Cr
Capacitor Do, D1 to D4 Diode RL Load PV1 to PV3 Solar cell module B1 to B3 Storage module

Claims (7)

A plurality of capacitors and a plurality of switches are provided, and the plurality of capacitors are mutually charged and discharged by repeatedly switching the plurality of switches to repeatedly switch the connection state of the capacitors included in the plurality of capacitors, A switched capacitor portion configured to adjust the voltage in such a direction as to eliminate variations in voltage applied to each of the capacitors included in the plurality of capacitors;
Switching configured to share a part of switches among the plurality of switches with the switched capacitor unit, receive an input voltage that is changed by switching of the part of switches, convert the input voltage, and output it as an output voltage And a converter unit ,
The switched capacitor unit is
First to n (n is an integer of 2 or more) capacitors connected in series;
An i-th set of switches consisting of a series-connected 2i-1 (i = 1 to n) switch and a 2ith switch connected in parallel to the i-th capacitor, from 1 to n First to nth switch sets respectively given to
An n + j node connected between a midpoint of two switches included in the j-th (j = 1 to n-1) switch set and a midpoint of two switches included in the j + 1th switch set And an n + 1th to 2n-1th capacitors respectively provided to j from 1 to n-1 as capacitors.
The switching converter unit shares any one of the first to n-th switch sets with the switched capacitor unit, and includes an inductor, and one of two switches included in the shared switch set is The switches in the shared switch set share the state of storing electromagnetic energy in the inductor by the current flowing therethrough and the state of releasing the electromagnetic energy from the inductor by the current flowing through the other of the two switches. A converter characterized in that it is configured as a switching converter unit that operates by switching by switching . A plurality of capacitors and a plurality of switches are provided, and the plurality of capacitors are mutually charged and discharged by repeatedly switching the plurality of switches to repeatedly switch the connection state of the capacitors included in the plurality of capacitors, A switched capacitor portion configured to adjust the voltage in such a direction as to eliminate variations in voltage applied to each of the capacitors included in the plurality of capacitors;
Switching configured to share a part of switches among the plurality of switches with the switched capacitor unit, receive an input voltage that is changed by switching of the part of switches, convert the input voltage, and output it as an output voltage And a converter unit,
The switched capacitor unit is
First to n (n is an integer of 2 or more) capacitors connected in series;
An i-th set of switches consisting of a series-connected 2i-1 (i = 1 to n) switch and a 2ith switch connected in parallel to the i-th capacitor, from 1 to n First to nth switch sets respectively given to
An n + j node connected between a midpoint of two switches included in the j-th (j = 1 to n-1) switch set and a midpoint of two switches included in the j + 1th switch set And an n + 1th to 2n-1th capacitors respectively provided to j from 1 to n-1 as capacitors.
The switching converter unit is configured as a resonant converter unit which shares any one of the first to n-th switch pairs with the switched capacitor unit, and includes an inductor and a capacitor. A converter characterized in that it is configured to output an output voltage dependent on the switching frequency of two switches included in a set of switches. Constructed from a parallel connection of solar cell modules for each of the n capacitors from the first in the converter according to any one of claims 1 to 2, converter system for a solar cell module. It constituted by connecting a solar cell module from the first of the converter according instead each of the capacitors of the n to any one of claims 1 to 2, converter system for a solar cell module. The converter system for electrical storage modules comprised by connecting an electrical storage module in parallel with each of said 1st-nth capacitor in the converter as described in any one of Claims 1 thru | or 2 . The converter system for storage modules comprised by replacing with each of said 1st to nth capacitor in the converter as described in any one of Claim 1 thru | or 2 , and connecting a storage module. The plurality of capacitors and the plurality of switches are respectively provided, and the plurality of capacitors are mutually charged and discharged by repeatedly switching the plurality of switches and repeatedly switching the connection state of the respective capacitors included in the plurality of capacitors. A first switched capacitor portion and a second switched capacitor portion, each configured to adjust the voltage in a direction to eliminate variations in voltage applied to each of the capacitors included in the plurality of capacitors. When,
An inductor is provided, one end of the inductor is connected to a part of switches among the plurality of switches included in the first switched capacitor unit, and the other end of the inductor is included in the plurality of switches included in the second switched capacitor unit. By being connected to a part of switches among the switches, the first switched capacitor unit and the second switched capacitor unit share a part of the plurality of switches and change according to switching of the shared switches It is configured to receive an input of an input voltage, convert it, and output an output voltage depending on a phase difference between switch switching in the first switched capacitor unit and switch switching in the second switched capacitor unit performed at the same frequency. A converter with a switching converter unit.

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