JP6755623B2 - PV power conditioner - Google Patents

Description

The present invention relates to a PV power conditioner, and more particularly to an improvement of a PV power conditioner that converts DC power supplied from a solar cell into AC power and outputs the power conditioner.

A PV (Photo Voltaic) power conditioner is a power conversion device that converts DC power supplied from a solar cell into AC power and outputs it. The PV power conditioner includes, for example, a boost chopper that boosts a DC voltage, an inverter that converts a DC voltage input from the boost chopper into an AC voltage, and a control circuit that controls the boost chopper and the inverter. The step-up chopper converts the input voltage input from the solar cell into an intermediate voltage according to the characteristics of the solar cell whose output voltage changes according to the amount of solar radiation. The control circuit feedback-controls the boost chopper so that the intermediate voltage is kept constant.

In addition, Patent Document 1 describes a fuel cell system that prevents the boost rate of the converter 3 from suddenly fluctuating when the voltage sensor V3 or V4 fails. In this system, a voltage sensor V4 that measures the voltage Vm between the input terminals of the inverter 6 is connected in parallel to the voltage sensor V3 that measures the output voltage Vo of the converter 3 as a verification voltage sensor. The failure of the voltage sensor V3 or V4 is detected based on the deviation between the output voltage Vo and the voltage Vm between the input terminals.

Japanese Unexamined Patent Publication No. 2013-110793

In the conventional PV power conditioner as described above, there is a problem that if a problem occurs in the voltage sensor that measures the intermediate voltage, the capacitor for holding the intermediate voltage is damaged. For example, it is conceivable that the resistance element of the voltage dividing circuit for measuring the intermediate voltage is damaged by electrolytic corrosion, the resistance value increases, or the resistance element becomes open. It is also conceivable that the voltage dividing circuit may be broken due to peeling of solder or the like. In such a case, the intermediate voltage cannot be measured correctly, and the boost chopper is feedback-controlled based on the erroneous measured value. Therefore, the intermediate voltage may increase and an overvoltage may be added to the capacitor.

Further, the inverter is feedback-controlled so that the output current of the inverter is kept constant, and the input voltage of the inverter, that is, the intermediate voltage has an operable range. For this reason, there is also a problem that if an erroneous measured value is acquired due to a malfunction of the voltage sensor and the intermediate voltage is reduced due to the influence, the inverter cannot operate normally.

If the circuit for measuring the intermediate voltage is duplicated as in the system described in Patent Document 1, even if a problem occurs in one circuit, the intermediate voltage can be measured correctly using the other circuit. it can. However, there is a problem that the manufacturing cost increases due to the duplication of circuits.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a PV power conditioner capable of suppressing damage to a capacitor holding an intermediate voltage. Another object of the present invention is to provide a PV power conditioner capable of suppressing malfunction of an inverter.

The PV power conditioner according to the first aspect of the present invention is a PV power conditioner that converts DC power supplied from a solar cell into AC power and outputs it, and intermediates the input voltage input from the solar cell. A boost chopper that boosts the voltage, an inverter that converts the intermediate voltage into an output voltage, an intermediate voltage sensor that measures the intermediate voltage and outputs the intermediate voltage measurement value, and the booster based on the intermediate voltage measurement value. The chopper control means for controlling the chopper and the sensor abnormality detecting means for detecting the abnormality of the intermediate voltage sensor are provided. The chopper control means stops the boost chopper based on the detection result of the sensor abnormality detecting means.

According to such a configuration, if a failure occurs in the intermediate voltage sensor that measures the intermediate voltage, the boost chopper stops, so that it is possible to suppress the application of an overvoltage to the capacitor that holds the intermediate voltage. Further, if a malfunction occurs in the intermediate voltage sensor, the boost chopper is stopped, so that the malfunction of the inverter can be suppressed.

In addition to the above configuration, the PV power conditioner according to the second aspect of the present invention has an output voltage sensor that measures the output voltage of the inverter and outputs the measured output voltage, and an inverter drive signal for driving the inverter. The sensor abnormality detecting means estimates the intermediate voltage from the output voltage measurement value and the inverter drive signal to obtain the voltage estimated value, and obtains the voltage estimated value from the output voltage measured value and the inverter drive signal. It is configured to detect an abnormality in the intermediate voltage sensor in comparison with the measured voltage value.

According to such a configuration, an abnormality of the intermediate voltage sensor can be detected by using the measured output voltage value and the inverter drive signal. Further, it is possible to detect an abnormality of the intermediate voltage sensor during the operation of the boost chopper and the inverter.

In addition to the above configuration, the PV power conditioner according to the third aspect of the present invention further includes an input voltage sensor that measures the input voltage and outputs the input voltage measurement value, and the chopper control means provides the boost chopper. A chopper drive signal for driving is generated, the sensor abnormality detecting means estimates the intermediate voltage from the input voltage measurement value and the chopper drive signal to obtain a voltage estimated value, and the voltage estimated value is obtained as the intermediate. It is configured to detect an abnormality in the intermediate voltage sensor in comparison with the measured voltage value.

According to such a configuration, an abnormality of the intermediate voltage sensor can be detected by using the input voltage measured value and the chopper drive signal. Further, it is possible to detect an abnormality of the intermediate voltage sensor during the operation of the boost chopper and the inverter.

In the PV power conditioner according to the fourth aspect of the present invention, in addition to the above configuration, the sensor abnormality detecting means repeatedly obtains the voltage estimation value and compares it with the intermediate voltage measurement value, and a plurality of comparison results. Is configured to detect an abnormality in the intermediate voltage sensor based on the above. According to such a configuration, it is possible to improve the detection accuracy when detecting an abnormality of the intermediate voltage sensor.

In the PV power conditioner according to the fifth aspect of the present invention, in addition to the above configuration, the sensor abnormality detecting means compares the intermediate voltage measurement value with a predetermined voltage lower limit value to detect an abnormality in the intermediate voltage sensor. It is configured to detect. According to such a configuration, the step-up chopper can be stopped promptly when the intermediate voltage measurement value is abnormally lowered due to the occurrence of a defect.

In addition to the above configuration, the PV power conditioner according to the sixth aspect of the present invention further includes an input voltage sensor that measures the input voltage and outputs the input voltage measurement value, and the sensor abnormality detecting means is the boost chopper. It is configured to detect an abnormality of the intermediate voltage sensor by comparing the input voltage measured value and the intermediate voltage measured value measured before the start-up of. According to such a configuration, it is possible to detect an abnormality in the intermediate voltage sensor before starting the boost chopper.

According to the present invention, if a failure occurs in the intermediate voltage sensor that measures the intermediate voltage, the step-up chopper stops, so that damage to the capacitor that holds the intermediate voltage can be suppressed. Further, if a malfunction occurs in the intermediate voltage sensor, the boost chopper is stopped, so that the malfunction of the inverter can be suppressed.

It is a figure which showed one structural example of PV power conditioner 1 by embodiment of this invention. It is a figure which showed the configuration example of the intermediate voltage sensor 23 of FIG. It is a flowchart which showed an example of the operation during operation in the PV power conditioner 1 of FIG. It is a flowchart which showed an example of the operation in the power-on state of the PV power conditioner 1 of FIG. It is a flowchart which showed an example of the operation at the time of startup in the PV power conditioner 1 of FIG.

<PV power conditioner 1>
FIG. 1 is a diagram showing a configuration example of a PV power conditioner 1 according to an embodiment of the present invention. The PV power conditioner 1 is a power conversion device that converts the power generated by the solar cell 2 into AC power and outputs it to the system power supply 3. The output voltage and frequency are matched with the system power supply 3, and the output waveform is output to the system power supply 3. Performs grid interconnection control to synchronize with. Further, the PV power conditioner 1 determines the power failure and power recovery of the system power supply 3, and performs system protection control to stop or restart the output. Further, the PV power conditioner 1 controls the operating point of the solar cell 2 and controls the operating point to maximize the generated power.

The PV power conditioner 1 includes an input capacitor 10, a boost chopper 11, an intermediate capacitor 12, an inverter 13, an output capacitor 14, a switch 15, a control circuit 16, an input voltage sensor 21, an input current sensor 22, and an intermediate voltage sensor 23. It is composed of an output current sensor 24 and an output voltage sensor 25. The control circuit 16 includes a chopper control unit 100, an inverter control unit 101, an overvoltage protection unit 102, and a sensor abnormality detection unit 103.

The solar cell 2 is a power generation device that receives sunlight and converts it into electric power. In the solar cell 2, the energy of sunlight is directly converted into DC power by utilizing the photovoltaic effect. For example, the solar cell 2 is composed of a photovoltaic module (photovoltaic module) in which a plurality of cells are connected in series or in parallel. The solar cell 2 can output a DC voltage of, for example, about 50V to 420V.

The grid power supply 3 is a power grid of an electric power company, that is, a commercial power supply supplied via a commercial system. The PV power conditioner 1 is, for example, a single-phase three-wire system and is connected to a system power supply 3 having a rated voltage of 100 V or 200 V and a frequency of 50 Hz or 60 Hz.

The input capacitor 10 is a capacitive element for smoothing the input current input from the solar cell 2, and is composed of, for example, an electrolytic capacitor. The input capacitor 10 is arranged between the solar cell 2 and the step-up chopper 11 and is connected in parallel to the solar cell 2.

The boost chopper 11 is a DC-DC converter circuit for boosting the input voltage input from the solar cell 2 to an intermediate voltage. The step-up chopper 11 is composed of an inductor 111, a switching element 112, a freewheeling diode 113, and a diode 114. The intermediate voltage is, for example, about 310V.

The inductor 111 is a choke coil that stores energy by the current flowing when the switching element 112 is on, and charges the intermediate capacitor 12 via the diode 114 by using the energy stored when the switching element 112 is in the off state. Is.

The switching element 112 is a semiconductor element that can be switched between an on state and an off state by a chopper drive signal from the chopper control unit 100. The switching element 112 includes a transistor having a predetermined withstand voltage and switching characteristics, for example, an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). Used. The chopper drive signal is input to the gate terminal of the switching element 112. The freewheeling diode 113 is a semiconductor element for protecting the switching element 112, and is connected in parallel between the source terminal and the drain terminal of the switching element 112.

The intermediate capacitor 12 is a capacitive element for holding an intermediate voltage, and is composed of, for example, an electrolytic capacitor. The intermediate capacitor 12 is arranged between the step-up chopper 11 and the inverter 13, and is connected in parallel to the step-up chopper 11.

The inverter 13 is a voltage conversion circuit for converting an intermediate voltage into an output voltage. The inverter 13 is a single-phase inverter, and is composed of four switching elements 131, four freewheeling diodes 132, and two inductors 133. The effective value of the output voltage is 200V.

The switching element 131 is a semiconductor element that can be switched between an on state and an off state by an inverter drive signal from the inverter control unit 101. As the switching element 131, a transistor having a predetermined withstand voltage and switching characteristics, for example, an IGBT or MOSFET is used. The inverter drive signal is input to the gate terminal of the switching element 131. The freewheeling diode 132 is a semiconductor element for protecting the switching element 131, and is connected in parallel between the source terminal and the drain terminal of the switching element 131.

The output capacitor 14 is a capacitive element for removing harmonic components from the output current output from the inverter 13. The output capacitor 14 is arranged between the inverter 13 and the switch 15, and is connected in parallel to the inverter 13. The switch 15 is a relay for disconnecting the inverter 13 from the system power supply 3.

The input voltage sensor 21 is a measuring instrument that measures an input voltage and outputs an input voltage measured value Vin, and is connected in parallel to, for example, an input capacitor 10. The input current sensor 22 is a measuring instrument that measures the input current and outputs the input current measured value Iin. For example, the input current sensor 22 is arranged between the input capacitor 10 and the inductor 111 of the step-up chopper 11.

The intermediate voltage sensor 23 is a measuring instrument that measures an intermediate voltage and outputs an intermediate voltage measurement value Vim, and is connected in parallel to, for example, an intermediate capacitor 12. The output current sensor 24 is a measuring instrument that measures the output current of the inverter 13 and outputs the measured output current value Iout. For example, the output current sensor 24 is arranged between the inductor 133 of the inverter 13 and the output capacitor 14. The output voltage sensor 25 is a measuring instrument that measures the output voltage of the inverter 13 and outputs the output voltage measurement value Vout, and is connected in parallel to, for example, the output capacitor 14.

The chopper control unit 100 generates a chopper drive signal for driving the boost chopper 11 based on the input voltage measurement value Vin, the input current measurement value Iin, and the intermediate voltage measurement value Vim, and outputs the chopper drive signal to the boost chopper 11. The chopper control unit 100 performs feedback control based on the intermediate voltage measurement value Vim so that the intermediate voltage holds a constant value Vref1. The voltage command value Vref1 of the intermediate voltage is predetermined.

The chopper control unit 100 specifies the target voltage Vref2 so that the output power P of the solar cell 2 is maximized based on the input voltage measurement value Vin and the input current measurement value Iin. Since the output characteristics (VI characteristics) of the solar cell 2 change depending on the amount of solar radiation and temperature, the output voltage of the solar cell 2, that is, the input voltage Vin is controlled and output by MPPT (maximum power point tracking) control. The output power P can be maximized by optimizing the operating points in terms of characteristics.

The chopper drive signal is, for example, a PWM (Pulse Width Modulation) signal, and the duty ratio of the pulse is the difference between the input voltage measurement value Vin and the target voltage Vref2, the intermediate voltage measurement value Vim, and the voltage command value Vref1. It is determined based on the difference of.

The inverter control unit 101 generates an inverter drive signal for driving the inverter 13 based on the output voltage measurement value Vout, the output current measurement value Iout, and the intermediate voltage measurement value Vim, and outputs the inverter drive signal to the inverter 13. The inverter control unit 101 performs feedback control based on the output current measurement value Iout so that the output current holds a constant value Iref.

The current command value Iref is specified based on the output voltage measurement value Vout and the intermediate voltage measurement value Vim. The inverter drive signal is, for example, a PWM (Pulse Width Modulation) signal, and the duty ratio of the pulse is determined based on the difference between the output current measurement value Iout and the current command value Iref.

The overvoltage protection unit 102 compares the intermediate voltage measurement value Vim with a predetermined voltage upper limit value, and stops the inverter 13 when the intermediate voltage measurement value Vim exceeds the voltage upper limit value Vmax. Prevent damage. The voltage upper limit value Vmax is, for example, 425V.

The sensor abnormality detection unit 103 detects an abnormality in the intermediate voltage sensor 23 and outputs the detection result to the chopper control unit 100 and the inverter control unit 101. The sensor abnormality detection unit 103 estimates the intermediate voltage from the output voltage measurement value Vout and the inverter drive signal to obtain the voltage estimation value Vinf1, and compares the voltage estimation value Vinf1 with the intermediate voltage measurement value Vim to obtain the intermediate voltage sensor. Detects 23 abnormalities.

According to this detection method, an abnormality of the intermediate voltage sensor 23 can be detected during the operation of the step-up chopper 11 and the inverter 13. Further, since the abnormality of the intermediate voltage sensor 23 is detected by using the output voltage measurement value Vout used for controlling the inverter 13, the increase in manufacturing cost is suppressed as compared with the case where the circuit for measuring the intermediate voltage is duplicated. be able to.

The voltage estimation value Vinf1 is obtained from the output voltage measurement value Vout and the duty ratio of the inverter drive signal by using a predetermined calculation formula. The abnormality of the intermediate voltage sensor 23 is detected by, for example, whether or not the absolute value of the error between the estimated voltage value Vinf1 and the intermediate voltage measured value Vim is a constant value Vth1 or less. The threshold value Th1 for determination is predetermined.

The duty ratio of the inverter drive signal is affected by the feedback control based on the output current measurement value Iout. Therefore, the voltage estimation value Vinf1 obtained from the output voltage measurement value Vout and the duty ratio of the inverter drive signal is different from the intermediate voltage measurement value Vim. If the output of the inverter 13 is stable, the estimated voltage value Vinf1 and the actual intermediate voltage generally match. Therefore, if there is no problem with the intermediate voltage sensor 23, the estimated voltage value Vinf1 is the intermediate voltage measurement value Vim. It should show close values.

In order to improve the detection accuracy, the sensor abnormality detection unit 103 repeatedly obtains the voltage estimation value Vinf1 and compares it with the intermediate voltage measurement value Vim, and detects the abnormality of the intermediate voltage sensor 23 based on the result of a plurality of comparisons. To do. When the sensor abnormality detection unit 103 detects, for example, that the absolute value of the error between the voltage estimated value Vinf1 and the intermediate voltage measured value Vim exceeds the constant value Th1, the sensor abnormality detection unit 103 obtains the voltage estimated value Vinf1 and obtains the intermediate voltage measured value Vim. Repeat the comparison with for a certain period of time. Then, when the sensor abnormality detection unit 103 detects that the absolute value of the error exceeds the constant value Th1 a plurality of times in succession within a fixed time, the intermediate voltage sensor 23 is said to have a problem. to decide.

The intermediate voltage is estimated from the input voltage measured value Vin and the chopper drive signal to obtain the voltage estimated value Vinf2, and the voltage estimated value Vinf2 is compared with the intermediate voltage measured value Vim to detect an abnormality in the intermediate voltage sensor 23. You may. The voltage estimation value Vinf2 is obtained from the input voltage measurement value Vin and the duty ratio of the chopper drive signal by using a predetermined calculation formula.

Further, the sensor abnormality detection unit 103 compares the intermediate voltage measurement value Vim with the predetermined voltage lower limit value Vmin to detect the abnormality of the intermediate voltage sensor 23. According to this detection method, an abnormality of the intermediate voltage sensor 23 can be detected when the power supply of the control circuit 16 is on. Further, when the intermediate voltage measurement value Vim is abnormally lowered due to the occurrence of a defect, the boost chopper 11 can be stopped promptly. The abnormality of the intermediate voltage sensor 23 is detected, for example, by whether or not the measured intermediate voltage value Vim is equal to or less than the lower limit voltage value Vmin.

When the input voltage exceeds the on threshold value, the PV power conditioner 1 automatically switches the power supply of the control circuit 16 to the on state. If the input voltage falls below the off threshold value, the power supply of the control circuit 16 is automatically switched to the off state, and the switching operation of the step-up chopper 11 and the inverter 13 is stopped. The off threshold is, for example, 40V. Therefore, a value smaller than the off threshold value, for example, about 20 V is specified for the voltage lower limit value Vmin.

Further, the sensor abnormality detection unit 103 detects an abnormality in the intermediate voltage sensor 23 by comparing the input voltage measurement value Vin and the intermediate voltage measurement value Vim measured before the boost chopper 11 is started. According to this detection method, it is possible to detect an abnormality in the intermediate voltage sensor 23 before starting the boost chopper 11. The abnormality of the intermediate voltage sensor 23 is detected by, for example, whether or not the absolute value of the error between the input voltage measurement value Vin and the intermediate voltage measurement value Vim is a constant value Th2 or less. The threshold value Th2 for determination is predetermined.

The chopper control unit 100 and the inverter control unit 101 stop the step-up chopper 11 and the inverter 13, respectively, based on the detection result of the sensor abnormality detection unit 103. When a problem occurs in the intermediate voltage sensor 23, the boost chopper 11 is stopped, so that it is possible to prevent an overvoltage from being applied to the intermediate capacitor 12 that holds the intermediate voltage. Further, if a problem occurs in the intermediate voltage sensor 23, the boost chopper 11 and the inverter 13 are stopped, so that the malfunction of the inverter 13 can be suppressed.

<Intermediate voltage sensor 23>
FIG. 2 is a diagram showing a configuration example of the intermediate voltage sensor 23 of FIG. The intermediate voltage sensor 23 is composed of a voltage dividing circuit including a plurality of resistance elements R1 and R2. The intermediate voltage is divided by five resistance elements R1 connected in series and two resistance elements R2 connected in parallel, and the intermediate voltage measurement value Vim is obtained based on the divided voltage.

For example, if the resistance value of R1 is 100 kΩ and the resistance value of R2 is 10 kΩ, the voltage dividing voltage can be reduced to 1/100 of the intermediate voltage. A metal film resistor is used for the resistance elements R1 and R2. By setting the resistance values of the resistance elements R1 and R2 to 100 kΩ or less, the resistance to electrolytic corrosion can be improved. Electrolytic corrosion is electrochemical corrosion, and as the electrolytic corrosion of the resistance element progresses, the resistance value rises and finally becomes an open state.

In such an intermediate voltage sensor 23, when any of the resistance elements R1 is damaged by electrolytic corrosion, the resistance value increases or is opened, so that the voltage division ratio changes and the intermediate voltage measurement value Vim decreases. .. When the intermediate voltage measurement value Vim decreases, the boost chopper 11 will endlessly increase the intermediate voltage due to the influence of the feedback control based on the intermediate voltage measurement value Vim. At this time, an overvoltage was applied to the intermediate capacitor 12, and the explosion-proof valve of the intermediate capacitor 12 may open or the intermediate capacitor 12 may explode.

In the PV power conditioner 1 according to the present embodiment, since the step-up chopper 11 is stopped by detecting the abnormality of the intermediate voltage sensor 23, it is possible to prevent the intermediate capacitor 12 from being damaged.

Steps S101 to S109 of FIG. 3 are flowcharts showing an example of the operation during operation of the PV power conditioner 1 of FIG. First, the PV power conditioner 1 acquires the measured value Vout of the output voltage (step S101) and acquires the inverter drive signal (step S102).

Next, the PV power conditioner 1 estimates the intermediate voltage from the measured value Vout of the output voltage and the duty ratio of the inverter drive signal to obtain the voltage estimated value Vinf1 (step S103), and compares it with the intermediate voltage measured value Vim. (Step S104). At this time, if the error between the voltage estimation value Vinf1 and the intermediate voltage measurement value Vim is a constant value Th1 or less (step S105), the PV power conditioner 1 ends this process.

On the other hand, if the error between the voltage estimation value Vinf1 and the intermediate voltage measurement value Vim exceeds the constant value Th1, the PV power conditioner 1 repeats the processing procedure from step S101 to step S105 until a certain time elapses. (Step S106).

When the PV power conditioner 1 detects that the error exceeds the constant value Th1 a plurality of times in succession within a fixed time (step S107), it determines that the intermediate voltage sensor 23 has a problem. (Step S108), the switching operation of the boost chopper 11 and the inverter 13 is stopped (step S109).

Steps S201 to S205 of FIG. 4 are flowcharts showing an example of the operation of the PV power conditioner 1 of FIG. 1 in the power-on state. This abnormality detection process is performed in a shorter cycle than the abnormality detection process shown in FIG. First, the PV power conditioner 1 acquires the measured value Vim of the intermediate voltage (step S201) and compares it with the voltage lower limit value Vmin (step S202). At this time, if the intermediate voltage measured value Vim exceeds the voltage lower limit value Vmin (step S203), the PV power conditioner 1 ends this process.

On the other hand, if the intermediate voltage measurement value Vim is equal to or less than the voltage lower limit value Vmin, the PV power conditioner 1 determines that the intermediate voltage sensor 23 has a problem (step S204), and determines that the step-up chopper 11 and the inverter 13 have a problem. The switching operation is stopped (step S205).

Steps S301 to S306 of FIG. 5 are flowcharts showing an example of the operation at startup in the PV power conditioner 1 of FIG. First, the PV power conditioner 1 acquires the measured value Vin of the input voltage (step S301) and acquires the measured value Vim of the intermediate voltage (step S302).

Next, the PV power conditioner 1 compares the input voltage measurement value Vin and the intermediate voltage measurement value Vim (step S303), and the error between the input voltage measurement value Vin and the intermediate voltage measurement value Vim is a constant value Th2 or less. If so, the intermediate voltage sensor 23 determines that it is normal (step S305), and starts the switching operation of the boost chopper 11 and the inverter 13 (step S306).

On the other hand, if the error between the input voltage measurement value Vin and the intermediate voltage measurement value Vim exceeds the constant value Th2, the PV power conditioner 1 determines that the intermediate voltage sensor 23 has a problem (step S304). ), End this process.

According to the present embodiment, if a problem occurs in the intermediate voltage sensor 23, the step-up chopper 11 is stopped, so that damage to the intermediate capacitor 12 can be suppressed. In particular, since the abnormality of the intermediate voltage sensor 23 is detected by using the output voltage measurement value Vout used for controlling the inverter 13 and the inverter drive signal, damage to the intermediate capacitor 12 can be suppressed without increasing the manufacturing cost. Can be done. Further, if a problem occurs in the intermediate voltage sensor 23, the boost chopper 11 and the inverter 13 are stopped, so that the malfunction of the inverter 13 can be suppressed.

1 PV power conditioner 2 Solar cell 3 System power supply 10 Input capacitor 11 Boost chopper 12 Intermediate capacitor 13 Inverter 14 Output capacitor 15 Switch 16 Control circuit 21 Input voltage sensor 22 Input current sensor 23 Intermediate voltage sensor 24 Output current sensor 25 Output voltage Sensor 100 Chopper control unit 101 Inverter control unit 102 Overvoltage protection unit 103 Sensor abnormality detection unit

Claims (4)

In a PV power conditioner that converts DC power supplied from a solar cell into AC power and outputs it.
A boost chopper that boosts the input voltage input from the above solar cell to an intermediate voltage,
An inverter that converts the above intermediate voltage to an output voltage,
An intermediate voltage sensor that measures the above intermediate voltage and outputs the intermediate voltage measurement value,
A chopper control means for controlling the boost chopper based on the intermediate voltage measurement value, and
Sensor abnormality detecting means for detecting abnormality of the intermediate voltage sensor and
An output voltage sensor that measures the output voltage of the above inverter and outputs the measured output voltage value,
It is equipped with an inverter control means for generating an inverter drive signal for driving the above inverter .
The sensor abnormality detecting means estimates the intermediate voltage from the output voltage measured value and the inverter drive signal to obtain the voltage estimated value, compares the voltage estimated value with the intermediate voltage measured value, and compares the voltage estimated value with the intermediate voltage measured value. Detects anomalies and
The chopper control means is a PV power conditioner characterized in that the step-up chopper is stopped based on the detection result of the sensor abnormality detecting means. The sensor abnormality detecting means is characterized in that it repeatedly obtains the estimated voltage value and compares it with the measured intermediate voltage value, and detects an abnormality of the intermediate voltage sensor based on the results of a plurality of comparisons. Item 1. The PV power conditioner according to Item 1 . The PV power conditioner according to claim 1 or 2 , wherein the sensor abnormality detecting means detects an abnormality of the intermediate voltage sensor by comparing the intermediate voltage measurement value with a predetermined voltage lower limit value. .. Further equipped with an input voltage sensor that measures the above input voltage and outputs the input voltage measurement value,
The sensor abnormality detection means, to claim 1, characterized in that the input voltage measured value measured before starting the step-up chopper and compares the intermediate voltage measurement value to detect an abnormality of the intermediate voltage sensor Described PV power conditioner.

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