JP6507078B2 - Control method and control device of power conditioner - Google Patents

Description

  The present invention relates to a control method and control device of a power conditioner.

  Conventionally, an inverter using a solar cell capable of switching between grid-connected operation (hereinafter referred to as “connected operation”) connected to a commercial power supply system and self-sustaining operation to be operated independently from the commercial power supply system is used. A power conditioner to be equipped has been proposed. The power conditioner of patent document 1 operate | moves by a single phase 2 wire output system at the time of interlocking | linkage driving | operation, and operate | moves by a single phase 3 wire output system at the time of a self sustaining.

JP 2003-18859 A

  Here, in the power conditioner, it is desired to reduce the loss of the inverter and to improve the characteristics such as the conversion efficiency. In particular, in the power conditioner of Patent Document 1, the O-phase (N-phase) control leg is stopped at the time of interconnected operation, and does not contribute to the characteristic improvement at the time of interconnected operation.

  Therefore, an object of the present invention made in view of the above problems is to provide a control method and a control device of a power conditioner capable of improving the characteristics during the interconnection operation.

In order to solve the above-mentioned subject, the control method of the power conditioner concerning one embodiment of the present invention is:
Operates in single-phase two-wire output mode during linked operation, and operates in single-phase three-wire output mode during autonomous operation, using a power conditioner control method with at least three legs consisting of an upper arm and a lower arm There,
The power conditioner has a middle point terminal of either the U phase controlling leg or the W phase controlling leg, and a switch connecting the middle point terminal of the O phase controlling leg.
During stand-alone operation, the switch is turned off to control each of the U-phase, the O-phase, and the W-phase with the at least three sets of legs;
During the interconnection operation, the switch is turned on to control two legs connected by the switch with the same control signal;
It is characterized by including.

Further, a control device of a power conditioner according to an embodiment of the present invention is
A power conditioner that operates in single-phase two-wire output mode during interconnection operation and operates in single-phase three-wire output mode during autonomous operation,
A control unit,
At least three legs including an upper arm and a lower arm;
A switch connecting between a middle point terminal of either the U phase controlling leg or the W phase controlling leg and the middle point terminal of the O phase controlling leg;
The control unit turns off the switch and controls each of the U-phase, O-phase, and W-phase with the at least three legs in the independent operation, and turns on the switch in the interconnection operation. The two legs connected by the switch are controlled by the same control signal.

  According to the control method and the control device of the power conditioner in the present invention, it is possible to improve the characteristics at the time of linked operation.

It is a figure showing composition of a power conditioner concerning one embodiment of the present invention. It is a flowchart which shows operation | movement of the power conditioner concerning one Embodiment of this invention. It is a figure which shows the output voltage in case a switch is normal, and the output voltage in the case of abnormality. It is a figure which shows the structure of the power conditioner which concerns on a modification.

  Hereinafter, embodiments of the present invention will be described.

Embodiment 1
The power conditioner 1 which concerns on one Embodiment of this invention is a power conditioner in which connection operation | use and a self sustaining are possible. As shown in FIG. 1, a power conditioner 1 according to an embodiment of the present invention is connected to a power supply 10 to supply power to a load, and an inverter 20, an inverter control unit 30, and a first voltage detection unit 51. , A second voltage detection unit 52, an interconnection relay 60, and an independent relay 70. The power source 10 is a solar cell, a fuel cell or the like. When the power supply 10 is a solar cell, DC power is supplied to the inverter 20 in response to the reception of sunlight, and the inverter 20 converts DC power into AC power and supplies AC power to the load. The load is, for example, a household electric appliance including a full wave load such as a liquid crystal television, a vacuum cleaner, and an electric stove, and a half wave load such as a dryer. The power conditioner 1 shown in FIG. 1 turns on the interconnection relay 60 and turns off the autonomous relay 70 during the interconnection operation to operate in a single-phase two-wire output system. On the other hand, at the time of self-sustaining operation, the interconnection relay 60 is turned off and the self-standing relay 70 is turned on to operate in the single-phase three-wire output system. The inverter control unit 30 corresponds to the control device of the present invention.

  The inverter 20 is a voltage type control inverter, and includes diodes (D1 to D6), switching elements (S1 to S6), capacitors (C1), and coils (L1 to L3) as shown in the figure, and the inverter control is performed. A DC input voltage is converted to an AC output voltage based on a PWM (Pulse Width Modulation) drive signal from the unit 30. The diodes D1 to D2 and the switching elements S1 to S2 constitute an O phase control leg 21 consisting of an upper arm and a lower arm for controlling the O phase, and the diodes D3 to 4 and the switching elements S3 to S4 constitute a U phase. A U-phase control leg 22 consisting of an upper arm and a lower arm for controlling is formed, and diodes D5-6 and switching elements S5 to S6 are a W-phase control leg consisting of an upper arm and a lower arm for controlling W phase. Configure 23. The inverter control unit 30 performs O based on the output voltage V of the inverter 20 detected by the first voltage detection unit 51 and the second voltage detection unit 52 (the potential difference between the U and O phases and the potential difference between the O and W phases). Control signals (signals for switching control of each switching element) to the phase control leg 21, the U-phase control leg 22 and the W-phase control leg 23 are generated.

  Furthermore, as shown in FIG. 1, the inverter 20 according to the present embodiment includes a switch 24 that connects the midpoint terminal of the O-phase control leg 21 and the midpoint terminal of the U-phase control leg 22. Specifically, between the switching element S1 and the switching element S2 of the O-phase control leg 21 (middle point terminal), and between the switching element S3 and the switching element S4 of the U-phase control leg 22 (middle point element) , Connected by a switch 24. The inverter control unit 30 turns on (closes) the switch 24 during the interconnection operation to control the leg that controls the O-phase during the autonomous operation and the leg connected with the same control signal. In the example shown in FIG. 1, the O-phase control leg 21 and the U-phase control leg 22 are controlled by the same control signal. Since the O-phase control leg 21 and the U-phase control leg 22 are controlled by the same control signal, the switching element S1 and the switching element S3 are turned on or off at the same timing. The switching element S2 and the switching element S4 are also turned on or off at the same timing.

  On the other hand, at the time of the self-sustaining operation, the inverter control unit 30 turns off the switch 24 (opens) and makes each of the phases by each leg (here, the O-phase control leg 21, U-phase control leg 22, W-phase control leg 23). It performs single-phase three-wire output by controlling.

  Here, if the switch 24 does not turn off due to welding or the like and performs a self-sustaining operation, the P-side element (switching element S3) of the U-phase control leg 22 and the N-side element (switching element) of the O-phase control leg 21 When S2) is simultaneously turned on, a PN short circuit occurs, and the inverter 20 breaks down. Therefore, the inverter control unit 30 detects whether or not the switch 24 operates normally before performing the self-sustaining operation. The operation of the inverter control unit 30 before the self-sustaining operation will be described with reference to the flowchart shown in FIG.

  First, the inverter control unit 30 performs control to turn off (open) the switch 24 in a state before the start of the autonomous operation (step S10). Then, the inverter control unit 30 performs a test run (step S20).

  Specifically, in the trial operation, the inverter control unit 30 inputs a predetermined signal to one of the legs connected to the switch 24 while the self-standing relay 70 is turned off. Here, as an example, the case where a signal that outputs a sine wave is input to the U-phase control leg 22 will be described. When the switch 24 is normal, as shown in FIG. 3A, only the output voltage of U phase (voltage between U and W phases) becomes a sine wave, and the output voltage of O phase (voltage between W and O phases) fluctuates do not do. On the other hand, when the switch 24 is abnormal, as shown in FIG. 3B, the output voltage of the U phase and the output voltage of the O phase also become sine waves. That is, the U-phase output voltage and the O-phase output voltage are the same. In FIG. 3, the W phase is used as a reference potential.

  The inverter control unit 30 acquires the voltages detected by the first voltage detection unit 51 and the second voltage detection unit 52, compares the U-phase output voltage with the O-phase output voltage at the time of trial operation, and both voltages If equal, the switch 24 is detected as abnormal. The inverter control unit 30 may determine that the output voltage is not abnormal if the output voltage is not 0 based on only the output voltage of the O phase.

  When the switch 24 is normal (step S30: YES), the inverter control unit 30 turns on the stand-alone relay 70 to start the stand-alone operation (step S40). On the other hand, when the switch 24 is not normal (Step S30: No), the stand-alone relay 70 is not turned on (off without starting the stand-alone operation) while the stand-alone relay 70 is turned off (Step S50).

  As described above, according to the above embodiment, at the time of linked operation, the switch 24 is turned on (closed), and the two legs connected to the switch 24 (in the above embodiment, the O phase control legs 21 and U In order to control the phase control leg 22) with the same control signal, the upper arm of the O phase control leg 21 and the upper arm of the U phase control leg 22 and the lower arm of the O phase control leg 21 and the lower phase of the U phase control leg 22 The arms are connected in parallel to reduce the on-resistance and the like, and the characteristics can be improved during the interconnection operation. Specifically, since the switching elements S1 and S3 and the switching elements S2 and S4 are connected in parallel, their on-resistance can be reduced. Further, the diodes D1 and D3 and the diodes D2 and D4 are connected in parallel to reduce their resistance. Therefore, the loss of inverter 20 can be reduced, and the conversion efficiency of power conditioner 1 can be improved.

  Further, according to the above-described embodiment, at the time of the self-sustaining operation, the inverter control unit 30 turns off the switch 24 to control each phase by each leg, so that single-phase three-wire output becomes possible. Furthermore, before the self-sustaining operation is performed, it is detected whether or not the switch 24 is operating normally, and when the switch 24 is not operating normally, the switch 24 does not turn off because of abnormal stop. Even if there is, the operation of inverter 20 can be reliably stopped. Therefore, the inverter 20 and the load are not damaged in the independent operation.

  Although the middle point terminal of O-phase control leg 21 and the middle point terminal of U-phase control leg 22 are connected by switch 24 in the above embodiment, the present invention is not limited to this. And the midpoint terminal of the W-phase control leg 23 may be connected by a switch 24. In this case, at the time of interconnection operation, the switch 24 is turned on to control two legs (the O-phase control leg 21 and the W-phase control leg 23) connected by the switch with the same control signal. The upper arm of the phase control leg 21 and the upper arm of the W phase control leg 23 are connected in parallel, and the lower arm of the O phase control leg 21 and the lower arm of the W phase control leg 23 are connected in parallel. Reduced.

  In the above embodiment, control is performed to input a signal that outputs a sine wave to the U-phase control leg 22 at the time of test operation, but the invention is not limited thereto. For example, a signal that outputs a rectangular wave or a pulse wave may be input.

(Modification)
Second Embodiment A second embodiment of the present invention will be described below. FIG. 4 is a view showing the configuration of a power conditioner 1 according to a modification. The same reference numerals are given to the same components as those in the above embodiment, and the description will be omitted. In the power conditioner 1 according to the modification, as compared with the configuration according to the above embodiment, the middle point terminal of the first U phase control leg 25 and the middle top terminal of the second U phase control leg 26 are originally connected, Further, the difference is that the middle point terminal of the first W phase control leg 27 and the middle point terminal of the second W phase control leg 28 are originally connected.

  In the power conditioner 1 according to the modification, a switch 29 is provided on a connection line connecting the middle point terminal of the first U-phase control leg 25 and the middle point terminal of the second U-phase control leg 26. Specifically, a switch 29 is provided on a connection line between switching element S1 and switching element S2 of first U-phase control leg 25 and between switching element S3 and switching element S4 of second U-phase control leg 26. Be

  Then, at the time of linked operation, the inverter control unit 30 turns on the switch 24 and controls the two legs connected to the switch 24 with the same control signal. That is, here, the first U-phase control leg 25 and the second U-phase control leg 26 are controlled by the same control signal. On the other hand, at the time of the self-sustaining operation, inverter control unit 30 turns off switch 29 to make each phase be each leg (here, first U-phase control leg 25, second U-phase control leg 26, first W-phase control leg 27, and A single-phase three-wire output is performed by control by the second W-phase control leg 28). The method of detecting an abnormality such as welding of the switch 29 is the same as that of the above embodiment, and thus the description thereof is omitted.

  As described above, according to the power conditioner 1 according to the modification, at the time of linked operation, the switch 29 is turned on, and the two legs connected to the switch 29 (in the above example, the first U-phase control leg 25 and In order to control the second U phase control leg 26) with the same control signal, the upper arm of the first U phase control leg 25 and the upper arm of the second U phase control leg 26, and the lower arm of the first U phase control leg 25 and the second U Since the lower control arm and the lower arm of the phase control leg 26 are connected in parallel to reduce the on-resistance and the like, it is possible to improve the characteristics during the interconnection operation. Specifically, since the switching elements S1 and S3 and the switching elements S2 and S4 are connected in parallel, their on-resistance can be reduced. Further, the diodes D1 and D3 and the diodes D2 and D4 are connected in parallel to reduce their resistance.

  Further, according to power conditioner 1 according to the above-described modification, inverter control unit 30 turns off switch 29 and controls each phase with each leg during self-sustaining operation, thus allowing single-phase three-wire output. . Furthermore, before the self-sustaining operation is performed, it is detected whether or not the switch 29 is operating normally, and when the switch 29 is not operating normally, the switch 29 does not turn off because of abnormal stop. Even if there is, the operation of inverter 20 can be reliably stopped.

  Although the inverter control unit 30 corresponds to the control device of the present invention in the above embodiment, the present invention is not limited to this. For example, the power conditioner 1 may be provided with a control unit provided outside the inverter 20, and the control unit may perform various controls performed by the inverter control unit 30. In this case, the power conditioner 1 itself including the control unit can also be referred to as a control device.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various changes and modifications based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, each means, functions included in each step, etc. can be rearranged so as not to be logically contradictory, and it is possible to combine or divide a plurality of means, steps, etc. into one. .

1 Power Conditioner 10 Power Supply 20 Inverter 21 O Phase Control Leg 22 U Phase Control Leg 23 W Phase Control Leg 24 Switch 25 First U Phase Control Leg 26 Second U Phase Control Leg 27 First W Phase Control Leg 28 Second W Phase Control Leg 29 switch 50 voltage detection unit 51 first voltage detection unit 52 second voltage detection unit 60 interconnection relay 70 self-sustaining relay

Claims (4)

Operates in single-phase two-wire output mode during linked operation, and operates in single-phase three-wire output mode during autonomous operation, using a power conditioner control method with at least three legs consisting of an upper arm and a lower arm There,
The power conditioner has a middle point terminal of either the U phase controlling leg or the W phase controlling leg, and a switch connecting the middle point terminal of the O phase controlling leg.
During stand-alone operation, the switch is turned off to control each of the U-phase, the O-phase, and the W-phase with the at least three sets of legs;
During the interconnection operation, the switch is turned on to control two legs connected by the switch with the same control signal;
Control method of the power conditioner including. Turning off the switch before performing the self-sustaining operation and individually operating the legs connected to the switch before turning on the self-sustaining relay;
Detecting an abnormality of the switch;
The control method of the power conditioner according to claim 1, wherein the self-sustaining operation is not started when the abnormality is detected.   3. The method according to claim 2, wherein, in the step of detecting the abnormality, the abnormality is detected based on the output voltage of the other leg when a predetermined signal is input to one of the legs connected to the switch. Control method of a power conditioner as described. A power conditioner that operates in single-phase two-wire output mode during interconnection operation and operates in single-phase three-wire output mode during autonomous operation,
A control unit,
At least three legs including an upper arm and a lower arm;
A switch connecting between a middle point terminal of either the U phase controlling leg or the W phase controlling leg and the middle point terminal of the O phase controlling leg;
The control unit turns off the switch and controls each of the U-phase, O-phase, and W-phase with the at least three legs in the independent operation, and turns on the switch in the interconnection operation. Control device for controlling the two legs connected by the switch with the same control signal.

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