JP2021035256A - Power conditioning system and diagnostic method of the same - Google Patents

Abstract

To provide a power conditioning system capable of diagnosing a relay that interconnects an output of a generator to a grid load or an independent load before the generator is started while suppressing an overcurrent from flowing through the relay.SOLUTION: Before starting the generator, a control unit of the power conditioning system charges a capacitor of a DC/AC inverter and then operates the DC/AC inverter to diagnose, with respect to a relay, a control state of the relay and, based on a result of detecting a current or voltage in a connection path of a relay connection circuit, diagnoses whether the relay is normal, welded, or disconnected.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power conditioning system and a method for diagnosing the power conditioning system.

Conventionally, a power conditioning system for connecting the output of a power generator (for example, a fuel cell) to each system is known (see, for example, Patent Document 1).

Here, in general, the output unit of the DC / AC inverter of the power conditioning system has "interconnected operation" connected to a commercial system or the like and "self-sustaining operation" connected at the time of emergency power generation.

A relay is inserted for each line in order to mechanically separate the output line for interconnection operation and the output line for independent operation used for these two operations.

These relays have a higher failure rate such as welding as compared with other electronic components.

In addition, depending on the conditions of the installation environment, the distance from the unit to the distribution board, which is the connection destination of the unit, may be long, and human error may occur when connecting these two output lines. It's easy to do. On the other hand, the fuel cell takes about half a day to start and stop.

Therefore, if there is a problem with the product during construction, a large amount of time is required for replacement.

Therefore, a method for diagnosing each output line is required even if the fuel cell is not started.

For example, in the conventional power conditioning system, the output of the DC / AC inverter is set to 200V when connected, while the output of the DC / AC inverter is set to 100V when connected, and the output voltage is controlled by controlling the output voltage in consideration of product size and cost. Is variable.

However, in such a conventional power conditioning system, the system voltage is used, and in particular, when diagnosing the output line for independent operation, the output line for independent operation is a 100V system, so that it can be used as it is for loads and parts. There is a problem that an overvoltage is applied and a failure occurs.

Further, if the system relay X is connected at the beginning of the diagnosis, there is a problem that an instantaneous overcurrent flows through the system relay X when the capacitor F of the DC / AC inverter DA is charged (FIG. 10).

JP 2016-158459

Therefore, the present invention makes a diagnosis of the relay while suppressing an overcurrent from flowing to a relay that connects the output of the generator to a system load or a self-sustaining load before starting the generator (for example, a fuel cell). It is an object of the present invention to provide a power conditioning system capable of performing the above.

The power conditioning system according to one aspect of the present invention is
A power conditioning system that connects the output of a generator to a system load or an independent load using a relay.
A DC / AC inverter that outputs power based on the generated power generated by the generator, and
An inrush current prevention circuit that supplies power to the DC / AC inverter by charging a capacitor connected to the input section of the DC / AC inverter.
A relay connection circuit that connects the output unit of the DC / AC inverter to the system load or the self-sustaining load, or connects the auxiliary device that becomes the load to the output unit of the DC / AC inverter or the system load.
The DC / AC inverter, the inrush current prevention circuit, and a control unit for controlling the relay provided in the connection path of the relay connection circuit are provided.
The control unit
Before starting the generator, after charging the capacitor of the DC / AC inverter, the DC / AC inverter is operated to control the relay and the connection of the relay connection circuit with respect to the relay. Based on the result of detecting the current or voltage in the path, it is characterized in that at least one of normal, welding failure, and disconnection failure is diagnosed.

In the power conditioning system
The generator is characterized by being a fuel cell.

In the power conditioning system
The auxiliary device is characterized by being a heater for heating the fuel cell and / or a heater for igniting the fuel cell.

In the power conditioning system
The inrush current prevention circuit
The electric power for charging the capacitor of the DC / AC inverter is supplied from the system load.

In the power conditioning system
The voltage for charging the capacitor is supplied from the system load to the inrush current prevention circuit without passing through the relay connection circuit.

In the power conditioning system
The DC / AC inverter
The overcurrent detection circuit for detecting the overcurrent of the DC / AC inverter is provided.
The control unit
At the time of diagnosing the relay connection circuit, before operating the DC / AC inverter, the threshold value for detecting the overcurrent by the overcurrent detection circuit is set to a second overcurrent threshold value lower than the first overcurrent threshold value in the normal state. , The feature is to set.

In the power conditioning system
The control unit
After operating the DC / AC inverter, the relay in the connection path on the self-sustaining load side of the relay connection circuit is operated to execute the diagnosis for the relay in the connection path on the self-sustaining load side. And.

In the power conditioning system
The control unit
After diagnosing the relay on the self-sustaining load side, the operation of the DC / AC inverter is stopped, and then the relay in the connection path on the system load side of the relay connection circuit is operated to connect the system load side. It is characterized by performing the above diagnosis for a relay in the path.

In the power conditioning system
The control unit
If it is determined to be normal in the diagnosis of the relay connection circuit, the threshold value for detecting the overcurrent by the overcurrent detection circuit is changed from the second overcurrent threshold value to the first overcurrent threshold value. , The feature is to start the generator.

In the power conditioning system
The first overcurrent threshold value is set to a value that does not exceed the current withstand capacity of the DC / AC inverter.
On the other hand, the second overcurrent threshold value is set to a value that does not exceed the current withstand capacity of the relay of the inrush current prevention circuit and the relay connection circuit.

In the power conditioning system
It is further provided with a DC / DC converter that is controlled by the control unit, converts the generated power generated by the generator, and outputs a DC voltage to the DC / AC inverter.

In the power conditioning system
The relay provided in the connection path of the relay connection circuit is a mechanical relay.

The method for diagnosing the power conditioning system according to one aspect of the present invention is as follows.
A power conditioning system that interconnects the output of an inverter to a system load or an independent load using a relay, and a power conditioning system that interconnects the output of an inverter to a grid load or an independent load using a relay. Then, power is supplied to the DC / AC inverter by charging a DC / AC inverter that outputs power based on the generated power generated by the generator and a capacitor connected to the input portion of the DC / AC inverter. The inrush current prevention circuit connects the output unit of the DC / AC inverter to the system load or the self-sustaining load, or the auxiliary device serving as a load and the output unit of the DC / AC inverter or the system load are connected. A method for diagnosing a power conditioning system including a relay connection circuit to be connected, the DC / AC inverter, the inrush current prevention circuit, and a control unit for controlling the relay provided in the connection path of the relay connection circuit. And
The control unit
Before starting the generator, after charging the capacitor of the DC / AC inverter, the DC / AC inverter is operated to control the relay and the connection of the relay connection circuit with respect to the relay. Based on the result of detecting the current or voltage in the path, it is characterized in that at least one of normal, welding failure, and disconnection failure is diagnosed.

The power conditioning system according to one aspect of the present invention is a power conditioning system that interconnects the output of a generator to a system load or an independent load by using a relay, and generates electric power based on the generated power generated by the generator. The output DC / AC inverter, the inrush current prevention circuit that supplies power to the DC / AC inverter by charging the capacitor connected to the input section of the DC / AC inverter, and the output section and system load of the DC / AC inverter. Alternatively, a relay connection circuit that connects an independent load or connects an auxiliary device that becomes a load and an output unit or system load of a DC / AC inverter, a DC / AC inverter, an inrush current prevention circuit, and a relay connection circuit. It is provided with a control unit for controlling a relay provided in the connection path of the above.

Then, the control unit charges the capacitor of the DC / AC inverter before starting the generator, and then operates the DC / AC inverter to control the relay and the connection path of the relay connection circuit with respect to the relay. Based on the result of detecting the current or voltage, it is diagnosed whether it is normal, welding failure, or disconnection failure at least.

As a result, according to the power conditioning system according to one aspect of the present invention, an overcurrent is applied to a relay that interconnects the output of the generator (for example, a fuel cell) with a system load or a self-sustaining load before starting the generator (for example, a fuel cell). The relay can be diagnosed while suppressing the flow.

FIG. 1 is a diagram showing an example of the configuration of the power conditioning system 100 according to the first embodiment. FIG. 2 is a diagram showing an example of the configuration of the DC / AC inverter DA of the power conditioning system 100 shown in FIG. FIG. 3 is a diagram showing an example of the configuration of the relay connection circuit Y of the power conditioning system 100 shown in FIG. FIG. 4 is a diagram showing an example of a sequence of diagnostic methods of the power conditioning system 100 according to the first embodiment. FIG. 5 is a flow chart showing an example of the flow corresponding to the sequence (1) shown in FIG. FIG. 6 is a flow chart showing an example of the flow corresponding to the sequences (2) and (5) shown in FIG. FIG. 7 is a flow chart showing an example of the flow corresponding to the sequence (3) shown in FIG. FIG. 8 is a flow chart showing an example of the flow corresponding to the sequence (4) shown in FIG. FIG. 9 is a flow chart showing an example of the flow corresponding to the sequence (6) shown in FIG. FIG. 10 is a diagram showing an example of the configuration of the DC / AC inverter DA of the conventional power conditioning system.

Hereinafter, the power conditioning system according to the present invention will be described with reference to the drawings.

[Power Conditioning System]
FIG. 1 is a diagram showing an example of the configuration of a system 1000 including the power conditioning system 100 according to the first embodiment. Further, FIG. 2 is a diagram showing an example of the configuration of the DC / AC inverter DA of the power conditioning system 100 shown in FIG. Further, FIG. 3 is a diagram showing an example of the configuration of the relay connection circuit Y of the power conditioning system 100 shown in FIG.

As shown in FIG. 1, the power conditioning system 100 uses a relay to output the output of the generator X to the first distribution board (self-sustaining load) B1 or the second distribution board (system load) B2. It is designed to be connected to.

The system load B2 is, for example, a 200V system. The self-supporting load B1 is, for example, a 100V system.

Further, the generator X is, for example, a fuel cell, but may be a generator other than the fuel cell.

The heater (auxiliary device) H is a heater for heating the fuel cell, which is the generator X, and / or a heater for igniting the fuel cell.

More specifically, for example, as shown in FIG. 3, the first auxiliary device H1 of the auxiliary device H is a heater (first AC heater H1) for heating a fuel cell which is a power generator X.

Then, for example, as shown in FIG. 3, the second auxiliary device H2 of the auxiliary device H is a heater for ignition of the fuel cell which is the generator X (second AC heater H2).

Here, the power conditioning system 100 includes, for example, as shown in FIGS. 1 to 3, a relay connection circuit Y, a control unit CNT, an inrush current prevention circuit TC, a DC / DC converter DD, and a DC / AC inverter. It is equipped with DA.

[DC / DC converter]
As shown in FIG. 1, the DC / DC converter DD is controlled by the control unit CNT, converts the generated power generated by the generator X, and outputs a DC voltage to the DC / AC inverter DA. There is.

[DC / AC Inverter DA]
As shown in FIG. 1, the DC / AC inverter DA converts the DC voltage output by the DC / DC converter DD into an AC voltage and supplies it to the relay connection circuit Y, for example.

That is, the DC / AC inverter DA is adapted to output electric power based on the generated electric power generated by the generator X.

Here, in this DC / AC inverter DA, for example, as shown in FIG. 2, the first input terminal TF1, the second input terminal TF2, the first output terminal TDA1, and the second output terminal TDA2 , Capacitor F, first node N1, second node N2, first MOS transistor M1, second MOS transistor M2, third MOS transistor M3, fourth MOS transistor M4, and so on. It includes a first choke coil L1, a second choke coil L2, an output capacitor CX, an overcurrent detection circuit D, and a gate drive circuit G.

The first input terminal TF1 and the second input terminal TF2 are connected to the output of the DC / DC converter DD, and the DC voltage output by the DC / DC converter DD is applied (FIG. 1). ).

Further, the first input terminal TF1 and the second input terminal TF2 are connected to the output of the inrush current prevention circuit TC, and the DC voltage output by the inrush current prevention circuit TC is applied (FIG. 6). 1).

A capacitor F is connected between the first input terminal TF1 and the second input terminal TF2, for example, as shown in FIGS. 1 and 2. In the example of FIG. 1, the capacitor F is shown outside the DC / AC inverter DA. Here, the capacitor F is defined as a component of the DC / AC inverter DA, but the capacitor F is defined as a component. It may be defined as a component other than the DC / AC inverter DA.

Then, when the capacitor F is charged, a predetermined electric power is supplied, and the DC / AC inverter DA is driven so that a predetermined voltage can be output.

Further, the first output terminal TDA1 and the second output terminal TDA2 are connected to the relay connection circuit Y, for example, as shown in FIG. Then, the AC voltage generated by the DC / AC inverter DA is output to the relay connection circuit Y from the first output terminal TDA1 and the second output terminal TDA2.

Further, in the first MOS transistor M1, for example, as shown in FIG. 2, the drain is connected to the first input terminal TF1 and the source is connected to the first node N1.

The first MOS transistor M1 is an nMOS transistor including a parasitic diode in the example of FIG.

The first MOS transistor M1 is turned on / off by a gate signal output from the gate drive circuit G.

Further, in the second MOS transistor M2, for example, as shown in FIG. 2, the drain is connected to the first node N1 and the source is connected to the second input terminal TF2.

The second MOS transistor M2 is an nMOS transistor including a parasitic diode in the example of FIG.

The second MOS transistor M2 is turned on / off by the gate signal output from the gate drive circuit G.

Further, in the third MOS transistor M3, for example, as shown in FIG. 2, the drain is connected to the first input terminal TF1 and the source is connected to the second node N2.

The third MOS transistor M3 is an nMOS transistor including a parasitic diode in the example of FIG.

The third MOS transistor M3 is turned on / off by the gate signal output from the gate drive circuit G.

Further, in the fourth MOS transistor M4, for example, as shown in FIG. 2, the drain is connected to the second node N2 and the source is connected to the second input terminal TF2.

The fourth MOS transistor M4 is an nMOS transistor including a parasitic diode in the example of FIG.

The fourth MOS transistor M4 is turned on / off by the gate signal output from the gate drive circuit G.

Further, one end of the first choke coil L1 is connected to the first node N1 and the other end is connected to the first output terminal TDA1.

Further, one end of the second choke coil L2 is connected to the second node N2, and the other end is connected to the second output terminal TDA2.

Further, the output capacitor CX is connected between the first output terminal TDA1 and the second output terminal TDA2.

The first choke coil L1, the second choke coil L2, and the output capacitor CX constitute an LC filter, but a filter circuit having the same function may be used instead.

Further, the overcurrent detection circuit D detects the overcurrent of the DC / AC inverter DA (current flowing through the first to fourth MOS transistors M1 to M4) (FIG. 2).

Further, the gate drive circuit G outputs the above-mentioned gate signal to the gates of the first to fourth MOS transistors M1 to M4 according to the control signal output by the control unit CNT, and outputs the first to fourth gate signals to the gates of the first to fourth MOS transistors M1 to M4. The operation of the MOS transistors M1 to M4 is controlled.

[Relay connection circuit]
As shown in FIG. 1, the relay connection circuit Y connects the output unit (first output terminal TDA1 and second output terminal TDA2) of the DC / AC inverter DA to the system load B2 or the self-supporting load B1. Alternatively, the auxiliary device that becomes the load is connected to the output unit (first output terminal TDA1 and second output terminal TDA2) of the DC / AC inverter DA or the system load B2.

Then, for example, as shown in FIG. 3, the relay connection circuit Y has a U-phase voltage terminal TIN1, a V-phase voltage terminal TIN2, a U-phase self-supporting terminal TU1, a V-phase self-supporting terminal TV1, and a U-phase. It includes a system terminal TU2, a V-phase system terminal TV2, and a system intermediate terminal TN2.

The U-phase U-phase voltage terminal TIN1 and the V-phase V-phase voltage terminal TIN2 are connected to the first output terminal TDA1 and the second output terminal TDA2 of the DC / AC inverter DA shown in FIG.

As a result, AC voltage is supplied from the DC / AC inverter DA to the U-phase voltage terminal TIN1 and the V-phase voltage terminal TIN2.

Further, the U-phase self-supporting terminal TU1 and the V-phase self-supporting terminal TV1 are connected to the self-supporting load B1 as shown in FIG. 3, for example.

Further, the U-phase system terminal TU2 and the V-phase system terminal TV2 are connected to the system load B2, for example, as shown in FIG.

Further, the system intermediate terminal TN2 is connected to the intermediate potential (for example, the ground potential) of the system load B2, for example, as shown in FIG.

Further, as shown in FIG. 3, for example, the relay connection circuit Y includes a first voltage detection circuit DV1, a second voltage detection circuit DV2, a third voltage detection circuit DV3, and a fourth voltage detection circuit. It includes a DV4, a fifth voltage detection circuit DV5, a sixth voltage detection circuit DV6, and a current detection circuit DI1.

Further, the first voltage detection circuit DV1 detects the voltage of the U-phase voltage terminal TIN1 and outputs the detection result to the control unit CNT (voltage detection 1).

Further, the second voltage detection circuit DV2 detects the voltage of the V-phase voltage terminal TIN2 and outputs the detection result to the control unit CNT (voltage detection 2).

Further, the third voltage detection circuit DV3 detects the voltage of the U-phase self-supporting terminal TU1 and outputs the detection result to the control unit CNT (voltage detection 3).

Further, the fourth voltage detection circuit DV4 detects the voltage of the V-phase self-supporting terminal TV1 and outputs the detection result to the control unit CNT (voltage detection 4).

Further, the fifth voltage detection circuit DV5 detects the voltage of the V-phase system terminal TV2 and outputs the detection result to the control unit CNT (voltage detection 5).

Further, the sixth voltage detection circuit DV6 detects the voltage of the U-phase system terminal TU2 and outputs the detection result to the control unit CNT (voltage detection 6).

Further, the current detection circuit DI1 detects the current flowing through the auxiliary devices H (first and second AC heaters H1 and H2) and outputs the detection result to the control unit CNT (current detection 1). ..

Further, as shown in FIG. 3, for example, the relay connection circuit Y includes a first system relay RY1, a second system relay RY2, a third system relay RY3, and a fourth system relay. RY4, the first self-supporting relay RY5, the second self-supporting relay RY6, the first auxiliary equipment relay RY7, the second auxiliary equipment relay RY8, the first switching relay RY9, and the second. The switching relay RY10, the first connection path (U-phase connection path), the second connection path (V-phase connection path), and the third connection path (N-phase connection path) are provided.

One end of the first system relay RY1 is connected to the U-phase voltage terminal TIN1, and the other end is connected to the U-phase system terminal TU2 via the second system relay RY2.

Further, one end of the second system relay RY2 is connected to the other end of the first system relay RY1, and the other end is connected to the U-phase system terminal TU2.

Further, one end of the third system relay RY3 is connected to the V-phase voltage terminal TIN2, and the other end is connected to the V-phase system terminal TV2 via the fourth system relay RY4.

Further, one end of the fourth system relay RY4 is connected to the other end of the third system relay RY3, and the other end is connected to the V-phase system terminal TV2.

Further, one end of the first self-supporting relay RY5 is connected to the V-phase voltage terminal TIN2, and the other end is connected to the V-phase self-supporting terminal TV1.

Further, one end of the second self-supporting relay RY6 is connected to the U-phase voltage terminal TIN1, and the other end is connected to the U-phase self-supporting terminal TU1.

Further, one end of the first auxiliary equipment relay RY7 is connected to the first switching relay RY9, and the other end is connected to one end of the first auxiliary equipment (first AC heater) H1.

Further, one end of the second auxiliary equipment relay RY8 is connected to the first switching relay RY9, and the other end is connected to one end of the second auxiliary equipment (second AC heater) H2.

Further, the first switching relay RY9 is in a state in which the other end of the second system relay RY2 (U-phase system terminal TU2) and one ends of the first and second auxiliary equipment relays RY7 and RY8 are connected. (System side connection state) and the state where the U-phase voltage terminal TIN1 and one end of the first and second auxiliary relays RY7 and RY8 are connected (inverter side connection state) can be switched. There is.

Further, the second switching relay RY10 has a state in which the system intermediate terminal TN2 and the other ends of the first and second auxiliary devices H1 and H2 are connected (system side connection state) and a V-phase voltage terminal TIN2. And the state in which the other ends of the first and second auxiliary devices H1 and H2 are connected (inverter side connection state) can be switched.

Each of the above-mentioned relays provided in the connection path of the relay connection circuit Y is a mechanical relay.

[Inrush current prevention circuit]
Further, as shown in FIG. 1, the inrush current prevention circuit TC supplies power to the DC / AC inverter DA by charging the capacitor F connected to the input portion of the DC / AC inverter DA, for example. ing.

Therefore, the DC / AC inverter DA is activated, for example, when the inrush current prevention circuit TC charges the capacitor F, and is in a state where a predetermined operation is possible.

In the inrush current prevention circuit TC, power for charging the capacitor F of the DC / AC inverter DA is supplied from the system load B2.

In particular, the electric power for charging the capacitor F is supplied from the system load B2 to the inrush current prevention circuit TC without passing through the relay connection circuit Y.

[Control unit]
As shown in FIG. 1, the control unit CNT controls each relay provided in the connection path of the DC / DC converter DD, the DC / AC inverter DA, the inrush current prevention circuit TC, and the relay connection circuit Y, for example. It has become like.

In particular, the control unit CNT drives the DC / AC inverter DA to control the supply of AC voltage to the U-phase voltage terminal TIN1 and the V-phase voltage terminal TIN2 (FIG. 2), and is used for the first and second independence. The operation of the relays RY5 and RY6, the relays RY1 to RY4 for the first to fourth systems, the relays RY7 and RY8 for the first and second auxiliary devices, and the relays RY9 and RY10 for switching the first and second systems is controlled by a control signal. It is designed to be controlled (Fig. 3).

For example, the control unit CNT turns on the first and second independent relays RY5 and RY6, and turns off the first to fourth system relays RY1 to RY4 to execute the independent operation. (Fig. 3).

On the other hand, the control unit CNT turns off the first and second self-supporting relays RY5 and RY6, and turns on the first to fourth system relays RY1 to RY4 to execute the interconnection operation. (Fig. 3).

Further, when the control unit CNT connects the generator X and the auxiliary device H, the control unit CNT turns on the first and second auxiliary device relays RY7 and RY8, and also turns on the first and second auxiliary device relays RY7 and RY8. The switching relays RY9 and RY10 are connected to the inverter side as described above (FIG. 3).

Further, when the auxiliary device H and the system load B2 are connected to each other, the control unit CNT turns on the first and second auxiliary device relays RY7 and RY8, and also turns on the first and second auxiliary device relays RY7 and RY8. The switching relays RY9 and RY10 are connected to the system side as described above (FIG. 3).

Here, the control unit CNT charges the capacitor F of the DC / AC inverter DA before starting the generator X, and then operates the DC / AC inverter DA to control the relays for each relay (FIG. 3). Based on the state and the result of detecting the current or voltage in the connection path of the relay connection circuit Y, it is diagnosed whether it is normal, welding failure, or disconnection failure at least.

Further, when diagnosing the relay connection circuit Y, the control unit CNT sets the threshold value for detecting the overcurrent by the overcurrent detection circuit D to be higher than the first overcurrent threshold value in the normal state before operating the DC / AC inverter DA. It is designed to be set to a low second overcurrent threshold.

Further, after operating the DC / AC inverter DA, the control unit CNT operates a relay (FIG. 3) in the connection path on the independent load B1 side of the relay connection circuit Y to make the connection path on the independent load B1 side. Diagnosis is performed for a certain relay (Fig. 3).

Further, the control unit CNT stops the operation of the DC / AC inverter DA after diagnosing the relay on the self-sustaining load B1 side, and then relays on the connection path on the system load B2 side of the relay connection circuit Y (FIG. 3). Is operated to perform diagnosis on the relay (FIG. 3) in the connection path on the system load B2 side.

Further, when the control unit CNT determines in the diagnosis of the relay connection circuit Y that it is normal, the overcurrent detection circuit D sets the threshold value for detecting the overcurrent from the second overcurrent threshold value to the first overcurrent threshold value. In addition to the change, the generator X is started.

The first overcurrent threshold value is set to a value that does not exceed the current withstand capacity of the DC / AC inverter DA, for example. On the other hand, the second overcurrent threshold value is set to a value that does not exceed the current withstand capacity of the relay of the inrush current prevention circuit TC and the relay connection circuit Y, for example.

Next, an example of a diagnostic method of the power conditioning system 100 having the above configuration will be described.

As described above, the control unit CNT charges the capacitor F of the DC / AC inverter DA before starting the generator X, and then operates the DC / AC inverter DA with respect to each relay (FIG. 3). Based on the control state of the relay and the result of detecting the current or voltage in the connection path of the relay connection circuit Y, it is diagnosed whether it is normal, welding failure, or disconnection failure.

For example, when diagnosing the relay connection circuit Y, the control unit CNT sets the threshold for detecting the overcurrent by the overcurrent detection circuit D to be higher than the first overcurrent threshold in the normal state before operating the DC / AC inverter DA. Set to a low second overcurrent threshold.

Then, after operating the DC / AC inverter DA, the control unit CNT operates a relay (FIG. 3) in the connection path on the self-sustaining load B1 side of the relay connection circuit Y to make the connection path on the self-sustaining load B1 side. Diagnostic is performed on a relay (FIG. 3).

Then, after diagnosing the relay on the self-sustaining load B1 side, the control unit CNT stops the operation of the DC / AC inverter DA, and then the relay in the connection path on the system load B2 side of the relay connection circuit Y (FIG. 3). Is operated to perform diagnosis on the relay (FIG. 3) in the connection path on the system load B2 side.

Here, FIG. 4 is a diagram showing an example of a sequence of diagnostic methods of the power conditioning system 100 according to the first embodiment. 5 to 9 are flow charts showing an example of the flow corresponding to the sequences (1) to (6) shown in FIG.

First, the control unit CNT, for example, as shown in FIG. 4, the first and second self-supporting relays RY5 and RY6, the first to fourth system relays RY1 to RY4, and the first and second supplements. The dexterous relays RY7 and RY8 are controlled to be open, and the first and second switching relays RY9 and RY10 are controlled to be connected to the inverter side as described above.

Then, the control unit CNT precharges the capacitor F of the DC / AC inverter DA by the inrush current prevention circuit TC, and supplies power to the DC / AC inverter DA (sequence (1) in FIG. 4).

In the sequence (1) of FIG. 4, the control unit CNT sets the first and second switching relays RY9 and RY10 while the first and second auxiliary relays RY7 and RY8 are open. It is in the state of side connection.

That is, for example, as shown in FIG. 5, the control unit CNT determines whether or not the charging of the capacitor F of the DC / AC inverter DA by the inrush current prevention circuit TC is successful (step S11), and when it is successful. Assuming that the sequence (1) was successful, proceeds to the next sequence (2).

On the other hand, when the control unit CNT determines that the charging has not been successful in step S11 and determines that the time-out has occurred (step S12), the control unit CNT considers that the diagnosis has failed and ends the flow.

Next, when the sequence (1) is successful, the control unit CNT executes confirmation of the first and second AC heaters H1 and H2 by the self-supporting line (sequence (2) in FIG. 4).

In the sequence (2) of FIG. 4, the control unit CNT drives the DC / AC inverter DA, and the first and second switching relays RY9 and RY10 are connected to the inverter side as described above. , The second auxiliary relays RY7 and RY8 are sequentially closed and energized.

Then, for example, as shown in FIG. 6, the control unit CNT determines whether the first AC heater H1 is energized (step S21), and when the first AC heater H1 is energized, FIG. It is determined whether or not the current value of the current detection 1 (detection result of the current detection circuit DI1) of 2 is appropriate (step S22).

Then, when the control unit CNT determines in step S22 that the current detection 1 is appropriate, it determines whether the second AC heater H2 is energized (step S23), and the second AC heater H2 is energized. In this case, it is determined whether or not the current value of the current detection 1 (detection result of the current detection circuit DI1) in FIG. 2 is appropriate (step S24).

Then, when the control unit CNT determines in step S24 that the current detection 1 is appropriate, the control unit CNT assumes that the sequence (2) is successful and proceeds to the next sequence (3).

On the other hand, if the control unit CNT determines in steps S22 and S24 that the current detection 1 is not appropriate, the control unit CNT considers that the diagnosis has failed and ends the flow (step S24).

Next, if the sequence (2) is successful, the control unit CNT executes welding confirmation of the self-supporting relay (sequence (3) in FIG. 4).

In the sequence (3) of FIG. 4, the control unit CNT drives the DC / AC inverter DA, and the first and second switching relays RY9 and RY10 are connected to the inverter side as described above. , The second auxiliary equipment relays RY7 and RY8 are open.

Then, for example, as shown in FIG. 7, the control unit CNT detects the voltage in the voltage detection 3 (detection result of the voltage detection circuit DV3) or the voltage detection 4 (detection result of the voltage detection circuit DV4) in FIG. Whether or not it is determined (step S31).

Then, when the control unit CNT determines in step S31 that the voltage is not detected in the voltage detection 3 and the voltage detection 4 (that is, there is no welding of the self-supporting relay), the sequence (3) is performed. Assuming success, the process proceeds to the next sequence (4).

If the control unit CNT determines in step S31 that the voltage is detected in the voltage detection 3 and the voltage detection 4 (that is, there is welding of the self-supporting relay), it is assumed that the diagnosis has failed. End the flow.

Next, the control unit CNT executes confirmation of incorrect connection between the independent line and the distribution board and confirmation of disconnection of the independent relay (sequence (4) in FIG. 4).

In the sequence (4) of FIG. 4, the control unit CNT drives the DC / AC inverter DA and closes the first and second self-supporting relays RY5 and RY6.

Then, for example, as shown in FIG. 8, the control unit CNT determines whether or not an overload has occurred in the self-supporting load B1 (step S41). Then, when an overload occurs, it is assumed that the diagnosis is a failure, and for example, the contractor is asked to judge the load.

On the other hand, if it is determined in step S41 that no overload has occurred, the contractor determines whether the voltage of the distribution board is normal, and if it is normal, the sequence (4) is successful. As a result, the process proceeds to the next sequence (5) (step S42).

If it is determined in step S42 that the voltage of the distribution board is not normal, the flow is terminated on the assumption that the diagnosis has failed.

Next, the control unit CNT confirms the AC heater by the system line (sequence (5) in FIG. 4).

In the sequence (5) of FIG. 4, the control unit CNT stops the DC / AC inverter DA and puts the first and second switching relays RY9 and RY10 in the state of the system side connection described above, and the first , The second auxiliary relays RY7 and RY8 are sequentially closed and energized.

Then, for example, as shown in FIG. 6 used in the sequence (2), the control unit CNT determines whether the first AC heater H1 is energized (step S21), and the first AC heater H1 is energized. If this is the case, it is determined whether or not the current value of the current detection 1 (detection result of the current detection circuit DI1) in FIG. 2 is appropriate (step S22).

Then, when the control unit CNT determines in step S22 that the current detection 1 is appropriate, it determines whether the second AC heater H2 is energized (step S23), and the second AC heater H2 is energized. In this case, it is determined whether or not the current value of the current detection 1 (detection result of the current detection circuit DI1) in FIG. 2 is appropriate (step S24).

Then, when the control unit CNT determines in step S24 that the current detection 1 is appropriate, the control unit CNT assumes that the sequence (5) is successful and proceeds to the next sequence (6).

On the other hand, if the control unit CNT determines in steps S22 and S24 that the current detection 1 is not appropriate, the control unit CNT considers that the diagnosis has failed and ends the flow.

Next, the control unit CNT executes welding and disconnection confirmation of the system relay (sequence (6) in FIG. 4).

In the sequence (6) of FIG. 4, the control unit CNT sequentially closes the first to fourth system relays RY1 to RY4, and then closes all of the first to fourth system relays RY1 to RY4. I have to.

Then, for example, as shown in FIG. 9, the control unit CNT does not detect the voltage in the voltage detection 1 or the voltage detection 2 while sequentially closing the first to fourth system relays RY1 to RY4. (That is, whether or not the relay for the system is welded) is determined (step S61).

Then, when the control unit CNT determines in step S61 that the voltage is not detected in the voltage detection 1 or the voltage detection 2, all of the first to fourth system relays RY1 to RY4 are closed. After determining that (step S62), it is determined whether or not the voltage is detected in the voltage detection 1 and the voltage detection 2 (that is, whether or not the relay for the system is disconnected) (step S63).

Then, when the control unit CNT determines in step S63 that the voltage is detected in the voltage detection 1 and the voltage detection 2, the control unit CNT considers that the sequence (6) is successful and ends the sequence.

On the other hand, the control unit CNT determines that the voltage is detected in the voltage detection 1 or the voltage detection 2 in step S61, and that the voltage is not detected in the voltage detection 1 and the voltage detection 2 in the step S63. If so, the flow is terminated as if the diagnosis failed.

After the above sequences (1) to (6) are completed, if the control unit CNT determines that the relay connection circuit Y is normal in the diagnosis, the overcurrent detection circuit D detects the overcurrent. The threshold value is changed from the second overcurrent threshold value to the first overcurrent threshold value, and the power generator X is started.

In the example of FIG. 4, the sequence (3) is executed after the sequence (2), but the sequence (2) and the sequence (3) may be executed at the same timing.

In the example of FIG. 6, the energization order of the first and second AC heaters in the sequence (2) or the sequence (5) may be reversed.

In the example of FIG. 4, the sequence (5) and the sequence (6) may be executed in the reverse order.

In the example of FIG. 9, until all the relays are closed in the sequence (6), there is no meaning in the order of relay connection, and any one of them may be connected.

If an abnormality is detected in the voltage on the system side in the voltage detection 5 and the voltage detection 6 shown in FIG. 3, the running sequence is interrupted or stopped.

Here, the sequence (2) is a diagnosis that requires the load to be energized, and the sequence (4) is a diagnosis that assumes no load but may be erroneously connected to the load. .. If a load failure or connection error occurs, the unit will be damaged due to a current that exceeds expectations. Therefore, it is characterized in that it is energized by using a DC / AC inverter DA capable of overcurrent protection.

However, when the generator is a fuel cell that takes several hours to start, it is difficult to supply power to the DC / AC inverter DA at the construction timing. Therefore, in the present invention, the inrush current prevention circuit TC is used as the input power source of the DC / AC inverter DA.

As described above, the power conditioning system according to the first embodiment is a power conditioning system that interconnects the output of the generator to the system load or the self-sustaining load by using a relay, and is used for the generated power generated by the generator. A DC / AC inverter that outputs power based on the power, an inrush current prevention circuit that supplies power to the DC / AC inverter by charging a capacitor connected to the input section of the DC / AC inverter, and an output of the DC / AC inverter. A relay connection circuit that connects the unit to the system load or self-sustaining load, or connects the auxiliary device that becomes the load to the output unit or system load of the DC / AC inverter, the DC / AC inverter, the inrush current prevention circuit, and , A control unit for controlling a relay provided in the connection path of the relay connection circuit.

Then, the control unit charges the capacitor of the DC / AC inverter before starting the generator, and then operates the DC / AC inverter to control the relay and the connection path of the relay connection circuit with respect to the relay. Based on the result of detecting the current or voltage, it is diagnosed whether it is normal, welding failure, or disconnection failure at least.

As a result, according to the power conditioning system according to one aspect of the present invention, an overcurrent is applied to a relay that interconnects the output of the generator (for example, a fuel cell) with a system load or a self-sustaining load before starting the generator (for example, a fuel cell). The relay can be diagnosed while suppressing the flow.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

100 Power Conditioning System B1 Independent Load (1st Distribution Board)
B2 system load (second distribution board)
Y Relay connection circuit CNT Control unit TC Inrush current prevention circuit DD DC / DC converter DA DC / AC Inverter F Condenser TF1 First input terminal TF2 Second input terminal TDA1 First output terminal TDA2 Second output terminal N1 First 1 node N2 2nd node M1 1st MOS transistor M2 2nd MOS transistor M3 3rd MOS transistor M4 4th MOS transistor L1 1st choke coil L2 2nd choke coil CX output capacitor D overcurrent detection circuit G gate drive circuit TIN1 U-phase voltage terminal TIN2 V-phase voltage terminal TU1 U-phase self-supporting terminal TV1 V-phase self-supporting terminal TU2 U-phase system terminal TV2 V-phase system terminal TN2 System intermediate terminal DV1 First voltage detection circuit DV2 Second voltage detection circuit DV3 Third voltage detection circuit DV4 Fourth voltage detection circuit DV5 Fifth voltage detection circuit DV6 Sixth voltage detection circuit DI1 Current detection circuit RY1 First system relay RY2 Second system Relay RY3 Third system relay RY4 Fourth system relay RY5 First self-supporting relay RY6 Second self-supporting relay RY7 First auxiliary equipment relay RY8 Second auxiliary equipment relay RY9 For first switching Relay RY10 Second switching relay

Claims (13)

A power conditioning system that connects the output of a generator to a system load or an independent load using a relay.
A DC / AC inverter that outputs power based on the generated power generated by the generator, and
An inrush current prevention circuit that supplies power to the DC / AC inverter by charging a capacitor connected to the input section of the DC / AC inverter.
A relay connection circuit that connects the output unit of the DC / AC inverter to the system load or the self-sustaining load, or connects the auxiliary device that becomes the load to the output unit of the DC / AC inverter or the system load.
The DC / AC inverter, the inrush current prevention circuit, and a control unit for controlling the relay provided in the connection path of the relay connection circuit are provided.
The control unit
Before starting the generator, after charging the capacitor of the DC / AC inverter, the DC / AC inverter is operated to control the relay and the connection of the relay connection circuit with respect to the relay. A power conditioning system characterized in diagnosing at least one of normal, welding failure, and disconnection failure based on the result of detecting a current or voltage in a path. The power conditioning system according to claim 1, wherein the power generator is a fuel cell. The power conditioning system according to claim 2, wherein the auxiliary device is a heater for heating the fuel cell and / or a heater for igniting the fuel cell. The inrush current prevention circuit
The power conditioning system according to any one of claims 1 to 3, wherein a voltage for charging the capacitor of the DC / AC inverter is supplied from the system load. The power conditioning system according to claim 4, wherein the voltage for charging the capacitor is supplied from the system load to the inrush current prevention circuit without passing through the relay connection circuit. The DC / AC inverter
The overcurrent detection circuit for detecting the overcurrent of the DC / AC inverter is provided.
The control unit
At the time of diagnosing the relay connection circuit, before operating the DC / AC inverter, the threshold for detecting the overcurrent by the overcurrent detection circuit is set to a second overcurrent threshold lower than the first overcurrent threshold in the normal state. , The power conditioning system according to any one of claims 1 to 5, wherein the power conditioning system is set. The control unit
After operating the DC / AC inverter, the relay in the connection path on the self-sustaining load side of the relay connection circuit is operated to execute the diagnosis for the relay in the connection path on the self-sustaining load side. The power conditioning system according to claim 6. The control unit
After diagnosing the relay on the self-sustaining load side, the operation of the DC / AC inverter is stopped, and then the relay in the connection path on the system load side of the relay connection circuit is operated to connect the system load side. The power conditioning system according to claim 7, wherein the diagnosis is performed on a relay in the path. The control unit
If it is determined to be normal in the diagnosis of the relay connection circuit, the threshold value for detecting the overcurrent by the overcurrent detection circuit is changed from the second overcurrent threshold value to the first overcurrent threshold value. The power conditioning system according to any one of claims 6 to 8, wherein the power generator is activated. The first overcurrent threshold value is set to a value that does not exceed the current withstand capacity of the DC / AC inverter.
On the other hand, any one of claims 6 to 9, wherein the second overcurrent threshold value is set to a value that does not exceed the current withstand capacity of the relay of the inrush current prevention circuit and the relay connection circuit. The power conditioning system described in. Any of claims 1 to 10, further comprising a DC / DC converter that is controlled by the control unit, converts the generated power generated by the generator, and outputs a DC voltage to the DC / AC inverter. The power conditioning system described in item 1. The power conditioning system according to any one of claims 1 to 11, wherein the relay provided in the connection path of the relay connection circuit is a mechanical relay. A power conditioning system that interconnects the output of an inverter to a system load or an independent load using a relay, and a power conditioning system that interconnects the output of an inverter to a grid load or an independent load using a relay. Then, power is supplied to the DC / AC inverter by charging a DC / AC inverter that outputs power based on the generated power generated by the generator and a capacitor connected to the input portion of the DC / AC inverter. The inrush current prevention circuit connects the output unit of the DC / AC inverter to the system load or the self-sustaining load, or the auxiliary device serving as a load and the output unit of the DC / AC inverter or the system load are connected. A method for diagnosing a power conditioning system including a relay connection circuit to be connected, the DC / AC inverter, the inrush current prevention circuit, and a control unit for controlling the relay provided in the connection path of the relay connection circuit. And
The control unit
Before starting the generator, after charging the capacitor of the DC / AC inverter, the DC / AC inverter is operated to control the relay and the connection of the relay connection circuit with respect to the relay. A method for diagnosing a power conditioning system, which comprises diagnosing at least one of normal, welding failure, and disconnection failure based on the result of detecting a current or voltage in a path.

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