JP5953698B2 - DC power conditioner and power conversion program - Google Patents

Description

  The invention disclosed in this specification relates to a technique for converting DC power generated by a DC power source such as a solar battery into AC power.

  Conventionally, there is a power conditioner that converts DC power generated by a DC power source such as a solar battery into AC power. As an example of this type of power conditioner, a boost chopper that optimizes the output voltage of the solar cell by increasing or decreasing the conductivity (boost ratio), and an inverter circuit that converts the output power of the boost chopper into AC power (See Patent Document 1). Here, the voltage of the AC power from the inverter circuit needs to coincide with a specified value determined by the supply destination. For example, when the supply destination is a commercial power system, the specified value is 200 V. Therefore, the inverter circuit may be input with a DC voltage of about 330 V in consideration of the system fluctuation range.

  On the other hand, the optimum value of the output voltage of the DC power supply may vary depending on its operating state and surrounding environment. In particular, since the optimum value of the output voltage of the solar cell changes depending on the number of solar cells connected in series, the outside air temperature, the weather, etc., the voltage control range for following the maximum power needs to be considered up to about 200 to 550V. Therefore, if the input voltage of the inverter circuit is set to 330 V, the output voltage of the DC power supply cannot be set to an optimum value exceeding 330 V by the boost chopper.

  Therefore, in the conventional power conditioner, the inverter circuit controls the input voltage to be kept constant at the maximum value of the output voltage of the solar cell, for example, 550 V, and the boost chopper supplies the DC power supply to the 550 V. The conductivity is increased or decreased so that the output voltage becomes the above optimum value.

JP 2010-278036 A

  However, in the conventional power conditioner, even if the output voltage of the solar cell is less than the maximum value, the inverter circuit always needs to convert the DC voltage boosted to the maximum value into the AC voltage of the specified value. Therefore, there is a problem that the power conversion loss in the inverter circuit is large.

  In the present specification, a technique capable of reducing the power conversion loss in the inverter circuit as compared with a configuration in which the input voltage of the inverter circuit is always maintained at the maximum value of the output voltage of the DC power supply is disclosed.

A power conditioner for a DC power source disclosed in the present specification includes a booster circuit that boosts an output voltage of the DC power source, an inverter circuit that converts an input DC voltage into an AC voltage having a predetermined value, and the DC A voltage detection circuit that outputs a detection signal corresponding to an output voltage of a power supply; and a control unit, wherein the control unit is configured to output the output voltage from the inverter circuit based on the detection signal from the voltage detection circuit. A voltage determination process for determining whether the voltage value is equal to or greater than a voltage value that can be converted into the specified value and less than a reference value that is lower than a maximum value of the output voltage of the DC power supply; If it is determined to be smaller than the reference value, while maintaining the input DC voltage to the inverter circuit to the reference value, electrodeposition of the output voltage of the DC power supply from the DC power supply A step-up voltage applying process but to control the values of maximum, if the output voltage by the voltage determination process is equal to or greater than the reference value, the output voltage without boost in the boost circuit, the And an output voltage applying process for controlling the output voltage of the DC power supply so as to maximize the power from the DC power supply while giving the input DC voltage to the inverter circuit.

According to the present invention, when it is determined that the output voltage of the DC power supply is less than the reference value, the boosted voltage application process is performed in which the voltage obtained by boosting the output voltage by the booster circuit is applied to the inverter circuit as the input DC voltage. . Here, the reference value is a voltage value that is equal to or higher than a voltage value that can be converted to a specified value by the inverter circuit and is lower than the maximum value of the output voltage of the DC power supply. The booster circuit performs so-called maximum power follow-up control so that the output voltage of the DC power supply becomes the maximum from the DC power supply, and maintains the input DC voltage to the inverter circuit at the reference value.
On the other hand, when it is determined that the output voltage of the DC power supply is equal to or higher than the reference value, the output voltage is not boosted by the booster circuit, and the output voltage of the DC power supply is set to maximize the power from the DC power supply. The voltage application process is executed, and the maximum power tracking control by the inverter circuit is performed . Therefore, the power conversion loss in the inverter circuit can be reduced as compared with the configuration in which the input voltage of the inverter circuit is always maintained at the maximum value of the output voltage of the DC power supply.

  In the power conditioner of the DC power supply, the control unit sets the boost ratio of the booster circuit to 1 in the output voltage application process, so that the output voltage is not boosted by the booster circuit. A configuration may be employed in which the inverter circuit is provided as an input DC voltage.

  According to the present invention, in the output voltage applying process, the boosting ratio of the booster circuit is set to 1 and the booster operation of the booster circuit is stopped, so that the output voltage is not boosted by the booster circuit and the input DC voltage As given to the inverter circuit. Thereby, in the output voltage application process, it is possible to reduce the power loss due to the boosting operation of the booster circuit.

In the power conditioner of the DC power source, the reference value may be a voltage value that can be converted to the specified value by the inverter circuit.
According to the present invention, the reference value is a voltage value that can be converted to a specified value by the inverter circuit. Therefore, compared with the case where the reference value is set to a value larger than the convertible voltage value, the power conversion loss in the inverter circuit can be reduced more effectively.

  The present invention can be realized in various modes such as a power conversion method, a computer program for realizing the function of the method or the power conditioner of the DC power supply, and a recording medium on which the computer program is recorded.

  According to the present invention, the power conversion loss in the inverter circuit can be reduced as compared with the configuration in which the output voltage of the DC power supply is uniformly boosted to the maximum value of the output voltage of the DC power supply.

Overall configuration diagram of a photovoltaic power generation system according to an embodiment Flow chart showing grid interconnection processing Flow chart showing the first power conversion process Graph showing output characteristics of solar cell panel Flow chart showing second power conversion process Graph showing the relationship between the output voltage of the solar panel and the input voltage of the inverter circuit

  A photovoltaic power generation system 1 according to an embodiment will be described with reference to FIGS.

(Configuration of solar power generation system)
As shown in FIG. 1, the solar power generation system 1 includes a solar battery panel 2 and a power conditioner 3. The solar cell panel 2 photoelectrically converts solar energy and outputs DC power, and is an example of a DC power source. The solar cell panel 2 is a two-dimensional array in which a plurality of solar cell modules are connected in series to form one string, and a plurality of the strings are connected in parallel.

  The power conditioner 3 is a grid-connected inverter that converts the DC power Px generated by the solar cell panel 2 into AC power of the system voltage value V1 while controlling the operation of the solar cell panel 2. Supply to commercial grid power supply 4. The system voltage value V1 is 200V AC and is an example of a specified value. Specifically, the power conditioner 2 includes a step-up chopper circuit 11, an inverter circuit 12, a voltage sensor 13, a current sensor 14, and a control unit 15.

  The step-up chopper circuit 11 changes the output voltage Vx of the solar cell panel 2 by increasing or decreasing the step-up ratio with the value of the input voltage Vy to the inverter circuit 12 as an upper limit value. Specifically, the boost chopper circuit 11 is a chopper booster circuit having a capacitor 11A, a coil 11B, a switching element 11C such as an IGBT (Insulated Gate Bipolar Transistor) or a thyristor, and a rectifier element 11D such as a diode.

  The inverter circuit 12 is a voltage-type current control type DC-AC inverter circuit, and converts the output power of the step-up chopper circuit 11 into AC power having a system voltage value V1. Specifically, the inverter circuit 12 includes, for example, a single-phase full bridge circuit 12A having four sets of switching elements and rectifying elements. A pair of input terminals of the full bridge circuit 12 </ b> A are connected to an output terminal of the boost chopper circuit 11 via a smoothing capacitor 16. The pair of output terminals of the full bridge circuit 12A is connected to the system power supply 4 via the low-pass filter 12B. By the low-pass filter 12B, it is possible to suppress the high-frequency leakage current accompanying the switching operation of the inverter circuit 12 described later from flowing into the external circuit.

  The voltage sensor 13 is an example of a voltage detection circuit, detects the output voltage Vx of the solar battery panel 2, and outputs a detection signal SG1 corresponding to the detected value. The current sensor 14 detects the output current Ix of the solar battery panel 2 and outputs a detection signal SG2 corresponding to the detected value. The control unit 15 includes a CPU 15 </ b> A and a memory 15, and the memory 15 stores a program for controlling the entire power conditioner 3. In addition, the control unit 15 receives the detection signal SG1 from the voltage sensor 13 and the detection signal SG2 from the current sensor 14, and thereby the operating voltage Vx of the solar cell panel 2 and the direct current that the solar cell panel 2 outputs. The power Wx can be grasped. In addition, the control unit 15 performs switching control by giving a control signal SG3 to the switching element 11C of the boost chopper circuit 11, and performs switching control by giving a control signal SG4 to the switching element of the inverter circuit 12. In the present embodiment, these switching controls are executed by PWM (Pulse Width Modulation) control.

(Operation of the inverter)
Based on the detection signal SG1 from the voltage sensor 13, the control unit 15 is connected to the grid connection shown in FIG. 2 on the condition that a predetermined time has passed while the open voltage of the solar cell panel 2 is equal to or higher than a predetermined activation voltage. Execute system processing and start interconnected operation. Specifically, the CPU 15A reads the program from the memory 15B and executes the grid interconnection process. The starting voltage is, for example, 275V, 330V, 440V, and the predetermined time is, for example, 10 seconds.

  The CPU 15A first initializes the count value K to 1 (S1), and based on the detection signals SG1 and SG2 from the voltage sensor 13 and the current sensor 14, the output voltage Vx (1) and the output current Ix (1 ) Is detected (S2). Next, the CPU 15A performs a voltage determination process for determining whether or not the detected output voltage Vx (K) is less than the voltage value V2 that can be converted into the system voltage value V1 (S3). The voltage value V2 that can be converted into the system voltage value V1 is, for example, 330 V, which is an example of a reference value.

(1) First Power Conversion Processing When the CPU 15A determines that the output voltage Vx (K) is less than the voltage value V2 that can be converted into the system voltage value V1 (S3: YES), the first power shown in FIG. A power conversion process is executed (S4). In the first power conversion process, the CPU 15A controls the continuity of each switching element of the inverter circuit 12 while performing the maximum power point tracking control by controlling the continuity of the switching element 11C of the boost chopper circuit 11. Thus, the input voltage Vy to the inverter circuit 12 is maintained at the voltage value V2 that can be converted into the system voltage value V1. Hereinafter, the conductivity of the boost chopper circuit 11 is referred to as a boost conductivity, and the conductivity of the inverter circuit 12 is referred to as an inverter conductivity. The conduction rate changes in proportion to the on-duty ratio and PWM value of the PWM control by the control unit 15.

Here, the output characteristics of the solar cell panel 2 vary depending on the amount of solar radiation, temperature, and the like, and in order to extract the maximum output from the solar cell panel 2, the output voltage Vx of the solar cell panel 2 against these variations, that is, It is preferable to change the operating voltage. The maximum power point tracking control refers to tracking control of the output voltage Vx so that the output power from the solar battery panel 2 is maximized, and hereinafter referred to as MPPT (Maximum Power Point Tracking) control. In this embodiment, the tracking range of the output voltage of the solar cell panel 2 shall be 200V-550V. In the following, an example of MPPT control will be described, but besides this,
A known method such as a general mountain climbing method can be used.

  The CPU 15A sets the boosting conductivity to the value D1 (K) corresponding to the output voltage Vx (K) detected in S2, and performs switching control of the boosting chopper circuit 11 (S11). This set value corresponds to a value obtained by dividing the value D1 (K) by a voltage V2 that can be converted into V1. Further, the CPU 15A fixes the inverter conduction rate of the inverter circuit 12 to the reference rate D2th, and performs switching control of the inverter circuit 12 (S11). The reference rate D2th is a continuity required to maintain the input voltage Vy to the inverter circuit 12 at the voltage V2 that can be converted to V1.

  Next, the CPU 15A changes the boosting conductivity to D1 (K + 1) obtained by adding α to the current value D1 (K), and increases the output voltage Vx of the solar cell panel 2 by a small amount (S12). Thereafter, the CPU 15A detects the output voltage Vx (K + 1) and the output current Ix (K + 1) of the solar cell panel 2 based on the detection signals SG1 and SG2 from the voltage sensor 13 and the current sensor 14 (S12). Subsequently, the CPU 15A determines that the output power Px (K) (= Vx (K) × Ix (K)) before changing the boosting conductivity is equal to the output power Px (K + 1) (= Vx ( It is determined whether it is smaller than (K + 1) × Ix (K + 1)) (S13). That is, the CPU 15A determines whether or not the output power Px has increased by increasing the output voltage Vx of the solar battery panel 2.

  If the CPU 15A determines that the output power Px has increased (S13: YES), it returns the step-up continuity from D1 (K + 1) to D1 (K), and again the output voltage Vx (K) of the solar cell panel 2, The output current Vx (K) is detected (S14). Then, the CPU 15A determines that the output power Px (K + 1) (= Vx (K + 1) × Ix (K + 1)) before changing the boosting conductivity is equal to the output power Px (K) (= Vx (K) after changing the boosting conductivity. ) × Ix (K)) is determined (S15). That is, the CPU 15A determines whether or not the output power Px has decreased by decreasing the output voltage Vx of the solar battery panel 2.

  If the CPU 15A determines that the output power Px has decreased (S15: YES), the increase / decrease in the output power Px in S13 and S15 is due to the change in the output voltage Vx of the solar panel 2, and the boosting conductivity is set. It changes to D1 (K + 1) (S16), and returns to S6 of FIG. 2 from this 1st power conversion process. On the other hand, if the CPU 15A determines that the output power Px has not decreased (S15: NO), the increase / decrease in the output power Px in S13 and S15 is caused by a change in the amount of solar radiation, and the boosting conduction rate Is changed to D1 (K), and the process returns to S6 of FIG. 2 from the first power conversion process. The CPU 15A adds 1 to the count value K in S6 and returns to S2.

  On the other hand, if the CPU 15A determines in S13 that the output power Px has not increased (S13: YES), the boosting conductivity is returned from D1 (K + 1) to D1 (K), and the solar cell panel 2 again. The output voltage Vx (K) and the output current Vx (K) are detected (S17). Then, the CPU 15A determines that the output power Px (K) (= Vx (K) × Ix (K)) after changing the boosting conductivity is equal to the output power Px (K + 1) (= Vx (K + 1) before changing the boosting conductivity. ) × Ix (K + 1)) is determined (S18). That is, the CPU 15A determines whether or not the output power Px has increased by decreasing the output voltage Vx of the solar battery panel 2.

  If the CPU 15A determines that the output power Px has increased (S18: YES), the increase / decrease in the output power Px in S13 and S18 is due to a change in the output voltage Vx of the solar panel 2, and the boosting conductivity is set. , D1 (K) is changed to D1 (K-1) obtained by subtracting only α, and the output voltage Vx of the solar battery panel 2 is decreased by a small amount (S19). From the first power conversion process, Return to S6. On the other hand, if the CPU 15A determines that the output power Px has not increased (S18: NO), it is assumed that the increase / decrease in the output power Px in S13 and S18 is due to a change in the amount of solar radiation. Is changed to D1 (K), and the process returns to S6 of FIG. 2 from the first power conversion process.

  FIG. 4 shows a graph showing the output characteristics of the solar cell panel 2, that is, the relationship between the output power Px and the output voltage Vx. When the solar cell panel 2 is operating at the point A in the figure during the execution of the first power conversion process, the output voltage Vx is changed from Va to Vb, Pb becomes larger than Pa, and again from Vb When the voltage is returned to Va and Pa becomes smaller than Pb, the step-up continuity is changed so that the output voltage Vx is changed to Vb. On the other hand, if Pa is equal to or greater than Pb when returning from Vb to Va, it is assumed that the change in the output power Px is due to the amount of solar radiation, and the output voltage Vx is set to Va without changing the boosting continuity. Keep it.

  On the other hand, when the solar cell panel 2 is operating at the point D in the figure during the execution of the first power conversion process, the output voltage Vx is changed from Vd to Ve, and Pd becomes larger than Pe. When returning from Ve to Vd and Pe becomes smaller than Pd, the step-up continuity is changed to change the output voltage Vx to Vc. On the other hand, if Pe is equal to or greater than Pd when returning from Ve to Vd, it is assumed that the change in the output power Px is due to the amount of solar radiation, and the output voltage Vx is changed to Vd without changing the boosting conduction rate. Keep it. Thus, in the MPPT control of the first power conversion process, the output voltage Vx is increased or decreased by distinguishing whether the change in the output power Px is due to the change in the amount of solar radiation or the change in the output voltage Vx. Therefore, the tracking control can be stably performed even when the amount of solar radiation changes suddenly.

(2) Second Power Conversion Processing When the CPU 15A determines that the output voltage Vx (K) is equal to or higher than the voltage value V2 that can be converted to the system voltage value V1 (S3: NO), the second power conversion process shown in FIG. A power conversion process is executed (S5). In the second power conversion process, the CPU 15A controls the inverter conduction ratio to execute the MPPT control similar to that in the first power conversion process, while the boost chopper circuit 11 supplies the output voltage Vx of the solar battery panel 2 to the power conversion process. Without being boosted, the inverter circuit 12 converts the voltage into an AC voltage.

  The CPU 15A fixes the boosting conductivity to the reference rate D1th and stops the boosting by the boosting chopper circuit 11 (S31). The reference rate D1th is a conduction rate for stopping the boosting by the boosting chopper circuit 11, and is specifically 1. This means that the step-up ratio is 1. Further, the CPU 15A sets the inverter conduction rate to a value D1 (K) corresponding to the output voltage Vx (K) detected in S2, and performs switching control of the inverter circuit 12 (S31). This set value is a value necessary for converting the output voltage Vx (K) into an AC voltage having the system voltage value V1. That is, the input voltage Vy to the inverter circuit 12 is not constant and changes according to the output voltage Vx (K).

  Next, the CPU 15A changes the inverter conductivity to D2 (K + 1) obtained by adding α to the current value D2 (K), and increases the output voltage Vx of the solar battery panel 2 by a small amount (S32). Thereafter, the CPU 15A detects the output voltage Vx (K + 1) and the output current Ix (K + 1) of the solar battery panel 2 (S32). Subsequently, the CPU 15A determines that the output power Px (K) (= Vx (K) × Ix (K)) before the change of the inverter conductivity is the output power Px (K + 1) (= Vx ( It is determined whether it is smaller than (K + 1) × Ix (K + 1)) (S33). That is, the CPU 15A determines whether or not the output power Px has increased by increasing the output voltage Vx of the solar battery panel 2.

  If the CPU 15A determines that the output power Px has increased (S33: YES), it returns the inverter continuity from D2 (K + 1) to D2 (K), and again the output voltage Vx (K) of the solar cell panel 2, The output current Ix (K) is detected (S34). Then, the CPU 15A determines that the output power Px (K + 1) (= Vx (K + 1) × Ix (K + 1)) before the change of the inverter conductivity is the output power Px (K) (= Vx (K) after the change of the inverter conductivity. ) × Ix (K)) is determined (S35). That is, the CPU 15A determines whether or not the output power Px has decreased by decreasing the output voltage Vx of the solar battery panel 2.

  If the CPU 15A determines that the output power Px has decreased (S35: YES), the increase / decrease in the output power Px in S33 and S35 is due to the change in the output voltage Vx of the solar panel 2, and the inverter continuity rate is set. It changes to D2 (K + 1) (S36), and returns to S6 of FIG. 2 from this 2nd power conversion process. On the other hand, if the CPU 15A determines that the output power Px has not decreased (S35: NO), the increase / decrease in the output power Px in S33 and S35 is caused by a change in the amount of solar radiation, and the inverter continuity rate Is changed to D2 (K), and the process returns to S6 of FIG. 2 from the second power conversion process.

  On the other hand, if the CPU 15A determines in S33 that the output power Px has not increased (S33: YES), the inverter conductivity is returned from D2 (K + 1) to D2 (K), and again the solar cell panel 2 The output voltage Vx (K) and the output current Ix (K) are detected (S37). Then, the CPU 15A determines that the output power Px (K) (= Vx (K) × Ix (K)) after the change of the inverter conductivity is the output power Px (K + 1) (= Vx (K + 1) before the change of the inverter conductivity. ) × Ix (K + 1)) is determined (S38). That is, the CPU 15A determines whether or not the output power Px has increased by decreasing the output voltage Vx of the solar battery panel 2.

  If the CPU 15A determines that the output power Px has increased (S38: YES), the increase / decrease in the output power Px in S33 and S38 is due to a change in the output voltage Vx of the solar panel 2, and the inverter continuity rate is set. , D2 (K) is changed to D2 (K-1) obtained by subtracting only α, and the output voltage Vx of the solar cell panel 2 is decreased by a small amount (S39). Return to S6. On the other hand, if the CPU 15A determines that the output power Px has not increased (S38: NO), the increase / decrease in the output power Px in S33 and S38 is due to a change in the amount of solar radiation, and the inverter conduction rate Is changed to D2 (K), and the process returns to S6 of FIG. 2 from the second power conversion process. Thus, in the MPPT control of the second power conversion process, the output voltage Vx is increased or decreased by distinguishing whether the change in the output power Px is due to the change in the solar radiation amount or the change in the output voltage Vx. Therefore, the tracking control can be stably performed even when the amount of solar radiation changes suddenly.

(Effect of this embodiment)
According to the present embodiment, when it is determined that the output voltage Vx of the solar battery panel 2 is less than the voltage value V2 that can be converted into the system voltage value V1 (S3 in FIG. 2: YES), the output voltage Vx is boosted. A first power conversion process is performed in which the voltage boosted by the chopper circuit 11 is applied to the inverter circuit 12 as an input DC voltage, and the input DC voltage is maintained at a voltage V2 that can be converted into V1 (see FIG. 3). On the other hand, when it is determined that the output voltage Vx of the solar battery panel 2 is equal to or higher than the voltage V2 that can be converted into the system voltage value V1 (S3: NO in FIG. 2), the output voltage Vx is boosted by the boost chopper circuit 11 Instead, a second power conversion process is performed in which the input current voltage is changed according to the output voltage while being applied to the inverter circuit 12 as an input DC voltage (see FIG. 5). Therefore, compared with the configuration in which the input voltage of the inverter circuit is always maintained at the maximum value V3 of the output voltage Vx of the solar cell panel 2, the power conversion loss in the inverter circuit 12 can be reduced.

  In the second power conversion process, the boost ratio of the boost chopper circuit 11 is set to 1 and the boost operation of the boost chopper circuit 11 is stopped, so that the output voltage Vx of the solar cell panel 2 is changed by the boost chopper circuit 11. The voltage is not boosted and is supplied to the inverter circuit 12 as an input DC voltage. Thereby, in the second power conversion process, power loss due to the boosting operation of the boosting chopper circuit 11 can be reduced.

  In addition, the first power conversion process is switched to the second power conversion process on condition that the output voltage Vx of the solar battery panel 2 is equal to or higher than the voltage value V2 that can be converted into the system voltage value V1 (see FIG. 3). . Therefore, on the condition that the output voltage Vx of the solar cell panel 2 has become a voltage value higher than the voltage value V2 that can be converted into the system voltage value V1, the configuration is switched from the first power conversion process to the second power conversion process. As compared with the above, the power conversion loss in the inverter circuit 12 can be reduced more effectively.

  FIG. 6 is a graph showing the relationship between the output voltage Vx of the solar cell panel 2 and the input voltage Vy to the inverter circuit 12. A solid line graph G1 in the figure shows a case where the grid interconnection process of FIG. 2 is executed for the output voltage Vx of the solar cell panel 2. A dashed-dotted line graph G2 in the figure shows a case where the output voltage Vx of the solar cell panel 2 is uniformly boosted to the maximum value V3 by the boost chopper circuit 11 as a comparative example.

  As shown in the graph G1, when the output voltage Vx of the solar battery panel 2 is less than the voltage value V2 that can be converted into the system voltage value V1, the output voltage Vx is converted into the system voltage value V1 by the first power conversion process. The voltage is boosted to a voltage value V2 that can be converted to. When the output voltage Vx of the solar battery panel 2 becomes equal to or higher than the voltage value V2 that can be converted into the system voltage value V1, the boosting by the boosting chopper circuit 11 is stopped and proportional to the output voltage Vx of the solar battery panel 2 The voltage thus applied is supplied to the inverter circuit 12. As described above, according to the present embodiment, in the first power conversion process, the boost chopper circuit 11 boosts the output voltage Vx of the solar battery panel 2 only to the minimum necessary voltage. For this reason, useless boosting operation can be suppressed and power conversion loss in the inverter circuit 12 can be reduced as compared with the comparative example.

  Further, according to the present embodiment, in the second power conversion process, the boost chopper circuit 11 is stopped, so that power loss due to the switching operation of the boost chopper circuit 11 can be suppressed as compared with the comparative example. In addition, since a voltage proportional to the output voltage Vx of the solar battery panel 2 is input to the inverter circuit 12, unnecessary boosting operation is suppressed as compared with the comparative example, and power conversion loss in the inverter circuit 12 is reduced. Can be reduced.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following various aspects are also included in the technical scope of the present invention.

  In the said embodiment, the solar cell panel 2 was mentioned as an example as an example of DC power supply. However, the DC power source is not limited to this, and any power source that outputs DC power, such as a power storage device, may be used. Note that the output voltage of the power storage device can also vary depending on the state of charge thereof.

  In the above embodiment, the system power supply 4 is taken as an example of the supply destination of the DC power output from the power conditioner 2. However, it can also be applied to other maximum power tracking control types.

  In the above embodiment, the chopper booster chopper circuit 11 is taken as an example of the booster circuit. However, the booster circuit is not limited to this, and may be, for example, a transformer booster circuit having a booster transformer. However, with the configuration of the above embodiment, the power loss due to the switching operation can be made substantially zero by turning off the switching element 11C in the second power conversion process, so that compared to the transformer booster circuit. The power conversion efficiency of the entire power conditioner can be improved.

  In the above embodiment, the voltage value V2 that can be converted into the system voltage V1 is given as an example of the reference value. However, the reference value is not limited to this, and may be a voltage value that is higher than the voltage V2 that can be converted into the system voltage V1 and lower than the maximum value V3 of the output voltage of the solar cell panel 2.

  In the above embodiment, the boost operation of the boost chopper circuit 11 is stopped in the second power conversion process. However, the present invention is not limited to this, and for example, the following configuration can be given. In FIG. 1, the bypass path connected from the solar cell panel 2 to the inverter circuit 12 without going through the boost chopper circuit 11 and the output side of the solar cell panel 2 are connected to the boost chopper circuit 11 and the bypass path. A switch circuit for selective connection is provided. Then, the control unit 15 controls the switch circuit so that the connection destination of the solar cell panel 2 is the boost chopper circuit 11 in the first power conversion process, and the connection destination of the solar cell panel 2 is set in the second power conversion process. This is a bypass path configuration.

  In the above embodiment, the control unit 15 is configured to include one CPU. However, the control unit 15 may have a configuration including a plurality of CPUs, may be configured with a hardware circuit such as an ASIC (Application Specific Integrated Circuit) such as an image processing circuit, or may be configured with a CPU and a hardware circuit. Good. In a configuration including a plurality of CPUs and hardware circuits, for example, a part or all of each process such as the voltage determination process, the first power conversion process, and the second power conversion process is shared by a plurality of CPUs. You may let them.

  In the said embodiment, what was memorize | stored in the memory 15B was mentioned as an example as an example of the program for power conversion. However, the power conversion program is not limited to this, and may be a non-volatile memory such as a hard disk device or a flash memory (registered trademark) or a storage medium such as a CD-R.

  2: Solar cell panel 3: Power conditioner 11: Boost chopper circuit 12: Inverter circuit 13: Voltage sensor 15: Control unit V2: Effective value

Claims (4)

A booster circuit that boosts the output voltage of the DC power supply;
An inverter circuit for converting an input DC voltage into an AC voltage having a predetermined value;
A voltage detection circuit that outputs a detection signal corresponding to the output voltage of the DC power supply;
A control unit,
The controller is
Based on the detection signal from the voltage detection circuit, the output voltage is equal to or higher than a voltage value that can be converted to the specified value by the inverter circuit and less than a reference value lower than the maximum value of the output voltage of the DC power supply. Voltage determination processing for determining whether or not
When it is determined in the voltage determination process that the output voltage is less than the reference value, the output voltage of the DC power supply is changed from the DC power supply while maintaining the input DC voltage to the inverter circuit at the reference value. Boosted voltage application processing for controlling the power of the power to the maximum value ,
When the output voltage is determined to be greater than or equal to the reference value in the voltage determination process, the output voltage is not boosted by the booster circuit, but is supplied to the inverter circuit as the input DC voltage, and the DC power supply A power conditioner for a DC power supply, comprising: an output voltage applying process for controlling the output voltage of the DC power supply so that power from the DC power supply is maximized . A power conditioner for a DC power supply according to claim 1,
In the output voltage applying process, the control unit sets the boosting ratio of the booster circuit to 1 to give the output voltage to the inverter circuit as the input DC voltage without boosting the booster circuit. A power conditioner for a DC power supply. A power conditioner for a DC power supply according to claim 1 or 2,
The power conditioner of a DC power source, wherein the reference value is a voltage value that can be converted to the specified value by the inverter circuit. A booster circuit that boosts the output voltage of the DC power supply, an inverter circuit that converts the input DC voltage into an AC voltage having a predetermined value, and a voltage detection circuit that outputs a detection signal corresponding to the output voltage of the DC power supply And a computer having a power conditioner of a DC power source comprising:
Based on the detection signal from the voltage detection circuit, the output voltage is equal to or higher than a voltage value that can be converted to the specified value by the inverter circuit and less than a reference value lower than the maximum value of the output voltage of the DC power supply. Voltage determination processing for determining whether or not
When it is determined in the voltage determination process that the output voltage is less than the reference value, the output voltage of the DC power supply is changed from the DC power supply while maintaining the input DC voltage to the inverter circuit at the reference value. Boosted voltage application processing for controlling the power of the power to the maximum value ,
When the output voltage is determined to be greater than or equal to the reference value in the voltage determination process, the output voltage is not boosted by the booster circuit, but is supplied to the inverter circuit as the input DC voltage, and the DC power supply And an output voltage applying process for controlling the output voltage so as to maximize the power from the DC power supply .

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