JP6897333B2 - Power supply and welding judgment method - Google Patents

Description

The present invention relates to a power supply device and a welding determination method.

A power conditioner (power conversion device) that performs grid interconnection with a commercial power system is provided with a function of opening an opening / closing unit (relay contact) to disconnect from the grid when grid interconnection is not performed. In addition to grid interconnection, power conditioners capable of self-sustaining output are provided with an opening / closing part between the power conditioner and the output terminal, and the opening / closing part is opened so that no voltage is output to the self-sustaining output terminal during grid interconnection operation. (For example, see FIG. 1 of Patent Document 1.).

As the relay used as such an opening / closing portion, if welding is performed, the disconnection function cannot be performed. Therefore, a relay having an auxiliary contact for detecting welding of the relay contact is used. Such relays are relatively expensive. Another feature is that the return time from the closed state to the opening of the road is relatively long.

Japanese Unexamined Patent Publication No. 2017-11929

In recent years, there is a self-sufficient system of electric power in which the generated electric power of photovoltaic power generation is stored in a storage battery and used by consumers instead of being sold. For example, some power supply devices such as UPS (Uninterruptible Power Supply) equipped with a storage battery can charge the storage battery and discharge it to consumers in a state of being connected to a commercial power system. If AC100V is provided as an auxiliary input other than the commercial power system, for example, from a power conditioner for photovoltaic power generation, electric power can be stored and used without waste.

In this case, the power supply device includes three systems of input / output: grid interconnection, self-sustaining output, and auxiliary input. A relay for disconnection is also required for the auxiliary input circuit, but the above-mentioned relay with a long recovery time cannot be used due to the UPS standard. However, if a relay with a short recovery time is adopted, welding detection cannot be performed because there is no auxiliary contact for welding detection.

In view of such a problem, the present invention facilitates welding of the auxiliary input opening / closing part without depending on the performance of the opening / closing part alone in the power supply device having three systems of input / output of grid interconnection, independent output, and auxiliary input. The purpose is to be able to detect.

The present disclosure includes the following inventions. However, the present invention is defined by the scope of claims.
The power supply device according to one expression of the present disclosure is a power supply device equipped with an inverter and performing conversion from DC to AC or vice versa, and at a first voltage via an AC electric circuit on the AC side of the inverter. A grid connection terminal connected to a commercial power system, a grid interconnection switching unit provided between the AC electric circuit and the grid connection terminal, and a second voltage lower than the first voltage branched from the AC electric circuit. An independent output terminal that outputs at a voltage of 2, an opening / closing portion for independent output provided between the AC electric circuit and the independent output terminal, an auxiliary input terminal that accepts an auxiliary input from the outside, the AC electric circuit and the auxiliary An auxiliary input opening / closing part provided between the input terminals, a first voltage sensor that detects a voltage between the two wires of the AC electric circuit, and two wires connecting the auxiliary input opening / closing part and the auxiliary input terminal. The second voltage sensor that detects the voltage between them, the function that controls the switching of the inverter, the switching section for grid interconnection, the switching section for independent output, and the switching section for auxiliary input are all opened. In the state of being controlled and without the auxiliary input, the inverter is made to output an unused inspection voltage lower than the second voltage, and the second voltage sensor is a voltage based on the inspection voltage. If no is detected, the auxiliary input opening / closing unit is normal, and if a voltage based on the inspection voltage is detected, the auxiliary input opening / closing unit is determined to be welded. I have.

Further, the welding determination method according to one expression of the present disclosure includes a function of mounting an inverter and interconnecting the system with the first voltage via the switching section for grid interconnection with the commercial power system, via the switching section for self-sustaining output. In a power supply device having a function of providing an independent output at a second voltage lower than the first voltage and a function of receiving an auxiliary input from the outside via an auxiliary input opening / closing unit, the control unit of the power supply device performs the function. In the welding determination method, the system connection opening / closing part, the self-sustaining output opening / closing part, and the auxiliary input opening / closing part are all controlled to be opened, and the auxiliary input is not provided. state, the inverter, the second lower voltage, to output the test voltage is not common, the voltage based on the inspection voltage is detected between the auxiliary input switching unit and the auxiliary input jacks If not, it is determined that the auxiliary input opening / closing part is normal, and if a voltage based on the inspection voltage is detected, the auxiliary input opening / closing part is welded.

According to the present invention, welding of the opening / closing part for auxiliary input can be easily detected without depending on the performance of the opening / closing part alone.

It is a figure which shows the circuit structure of the power supply device. It is a figure which shows an example of the circuit structure inside the power conversion part. The same figure as in FIG. 1 is a diagram specifically showing the operation of each opening / closing part at the time of grid connection. The same figure as in FIG. 1 is a diagram specifically showing the operation of each opening / closing portion at the time of self-sustaining output. The same figure as in FIG. 1 is a diagram specifically showing the operation of each opening / closing portion at the time of auxiliary input. The same figure as in FIG. 1 is a diagram specifically showing the operation of each opening / closing part when the auxiliary input opening / closing part is welded and there is no auxiliary input. The same figure as in FIG. 1 is a diagram specifically showing the operation of each opening / closing part when the auxiliary input opening / closing part is welded and there is an auxiliary input. It is a flowchart which shows an example of welding check of the opening / closing part for auxiliary input. It is a flowchart which shows another example of the welding check of the opening / closing part for auxiliary input. The same figure as in FIG. 1 is a diagram showing a state in which the self-supporting output opening / closing portion is welded, and the grid interconnection opening / closing portion and the auxiliary input opening / closing portion are normally opened.

[Summary of Embodiment]
The gist of the embodiment of the present invention includes at least the following.

(1) This is a power supply device equipped with an inverter and performing conversion from DC to AC or vice versa, and is connected to a commercial power system with a first voltage via an AC electric circuit on the AC side of the inverter. The grid connection terminal to be connected, the switching unit for grid interconnection provided between the AC electric circuit and the grid connection terminal, and a second voltage branched from the AC electric circuit and output at a second voltage lower than the first voltage. Between the self-supporting output terminal, the self-supporting output opening / closing portion provided between the AC electric circuit and the self-sustaining output terminal, the auxiliary input terminal for receiving an auxiliary input from the outside, and the AC electric line and the auxiliary input terminal. Detects the voltage between the auxiliary input switching unit provided in the above, the first voltage sensor that detects the voltage between the two lines of the AC electric circuit, and the voltage between the two wires connecting the auxiliary input opening / closing unit and the auxiliary input terminal. The second voltage sensor, the function of switching control of the inverter, and the control to open all of the system interconnection opening / closing part, the self-sustaining output opening / closing part, and the auxiliary input opening / closing part. In addition, when the inverter is made to output an unused inspection voltage lower than the second voltage and the second voltage sensor does not detect a voltage based on the inspection voltage in the absence of the auxiliary input. The auxiliary input opening / closing unit is normal, and when a voltage based on the inspection voltage is detected, the auxiliary input opening / closing unit is provided with a control unit having a function of determining that the auxiliary input opening / closing unit is welded.

In such a power supply device, the switching section for grid interconnection, the switching section for independent output, and the switching section for auxiliary input should all be open, and the inverter is not used regularly because it is lower than the second voltage. By outputting the inspection voltage, it is possible to determine whether or not the auxiliary input opening / closing portion is welded. That is, if the auxiliary input opening / closing portion is normally opened, the second voltage sensor does not detect the voltage based on the inspection voltage. On the other hand, when the second voltage sensor detects a voltage based on the inspection voltage, it can be determined that the auxiliary input opening / closing portion is welded. In this way, even if the auxiliary input opening / closing unit itself does not have a function of sending a welding signal to the outside, it is possible to determine whether or not the auxiliary input opening / closing unit is welded by verification using the inspection voltage. Since the inspection voltage is lower than the second voltage, damage to the circuit element can be prevented and electric shock to the human body can be suppressed.

(2) Further, in the power supply device of (1), a noise filter is provided between the self-supporting output terminal and the self-supporting output opening / closing part, and a current flows between the noise filter and the self-supporting output opening / closing part. A current sensor may be provided to detect the noise.
In this case, welding of the self-supporting output opening / closing portion can also be detected. That is, when the inverter outputs the inspection voltage or the second voltage while the independent output opening / closing part is controlled to open, the independent output opening / closing part is normal unless the current sensor detects the current. When the current sensor detects the current due to the current flowing through the capacitance component of the noise filter or the specific load connected to the self-supporting output terminal, it can be determined that the self-supporting output switching portion is welded.

(3) Further, from the viewpoint of the method, the function of mounting an inverter and connecting the system with the commercial power system via the switching section for grid interconnection at the first voltage, and the first function via the switching section for self-sustaining output. A welding determination method performed by the control unit of the power supply device in a power supply device having a function of providing an independent output at a second voltage lower than the voltage of the above voltage and a function of receiving an auxiliary input from the outside via an auxiliary input opening / closing unit. (A) The system connection opening / closing part, the self-sustaining output opening / closing part, and the auxiliary input opening / closing part are all controlled to be opened, and the auxiliary input is not provided. b) in this state, the inverter is lower than said second voltage, to output the test voltage is not common, the inspection with the (c) the auxiliary input switching unit and the auxiliary input jacks If the voltage based on the voltage is not detected, the auxiliary input opening / closing part is normal, and if the voltage based on the inspection voltage is detected, it is determined that the auxiliary input opening / closing part is welded. This is a judgment method.

In such a welding determination method in a power supply device, the inverter is connected to the second voltage with the switching section for grid interconnection, the switching section for independent output, and the switching section for auxiliary input all open. By outputting a low, non-regular inspection voltage, it is possible to determine whether or not the auxiliary input opening / closing portion is welded. That is, if the auxiliary input opening / closing portion is normally opened, the second voltage sensor does not detect the voltage based on the inspection voltage. On the other hand, when the second voltage sensor detects a voltage based on the inspection voltage, it can be determined that the auxiliary input opening / closing portion is welded. In this way, even if the auxiliary input opening / closing unit itself does not have a function of sending a welding signal to the outside, it is possible to determine whether or not the auxiliary input opening / closing unit is welded by verification using the inspection voltage. Since the inspection voltage is lower than the second voltage, damage to the circuit element can be prevented and electric shock to the human body can be suppressed.

[Details of Embodiment]
Hereinafter, the power supply device and the welding detection method according to the embodiment of the present invention will be described with reference to the drawings.

<< Circuit configuration example >>
FIG. 1 is a diagram showing a circuit configuration of the power supply device 100. The power supply device 100 is provided between the storage battery 1 at the end on the DC side and the three external AC electric circuits of "system interconnection", "self-sustaining output", and "auxiliary input". In the figure, it will be described as “upstream side” as it goes to the AC side when viewed from the storage battery 1.

The storage battery 1 is a component of the power supply device 100 if it is built in the power supply device 100, but if it is installed outside (separately installed), it is apparently not necessarily a component of the power supply device 100. Sometimes I can't say that.

First, regarding the main circuit element, the power conversion unit 2 is connected to the DC output (P line, N line) of the storage battery 1. The power conversion unit 2 can perform bidirectional conversion from direct current to alternating current or vice versa. An LC filter circuit using an AC reactor 3 and an AC side capacitor 4 and a noise filter (internal configuration is a common mode choke, the same applies hereinafter) 5 are connected to the AC side of the power conversion unit 2. On the upstream side of the noise filter 5, there is an internal AC electric circuit (AC bus) 6 common to the three external AC electric circuits of "system interconnection", "self-sustaining output", and "auxiliary input".

Between the AC electric circuit 6 and the grid connection terminal 12 of the grid interconnection, an opening / closing part (grid interconnection relay) 7 for grid interconnection, a capacitor 8, a varistor 9, and a series of varistors 10 and 11 are formed. Is provided as shown in the figure.

The system interconnection opening / closing unit 7 has contacts that can be opened / closed on the U line side and the W line side, respectively. For example, AC 200V is applied between the U line and the W line. The intermediate connection point of the series of varistor 10 and 11 is connected to the O (N) line of the system connection terminal 12. Therefore, an AC 200V is applied between the U line and the W line of the system connection terminal 12, and an AC 100V is applied between the U line and the O line and between the W line and the O line, respectively.

Next, between the AC electric circuit 6 and the self-supporting output terminal 18, a capacitor 13, a self-supporting output switching unit (self-supporting output relay) 14, a fuse 15, a varistor 16, and a noise filter 17 are shown. It is provided as follows.
The self-supporting output opening / closing unit 14 has contacts that can be opened / closed on the L1 line side and the N1 line side, respectively. For example, AC 100V is output between the L1 line and the N1 line.

Further, between the AC electric circuit 6 and the auxiliary input terminal 24, auxiliary input opening / closing portions 19p, 19n, a noise filter 20, a capacitor 21, a fuse 22, and a varistor 23 are provided as shown in the figure. ing. The two contacts of the auxiliary input opening / closing parts 19p and 19n operate in synchronization with each other. Hereinafter, when 19p and 19n are collectively referred to, they are referred to as an auxiliary input opening / closing unit 19. It should be noted that the two contacts are divided into two 1-contact relays, which is an advantageous example in terms of cost, but the present invention is not limited to this, and one opening / closing part having two contacts may be used. ..

The auxiliary input opening / closing portion 19p has a contact that can be opened / closed on the L line side. Further, the auxiliary input opening / closing unit 19n has a contact that can be opened / closed on the N-ray side. For example, AC 100V is input from the outside between the L line and the N line.

The circuit components for measurement control include a current sensor 31 that detects the current flowing through the AC reactor 3, a voltage sensor 32 that detects the voltage across the capacitor 8, a voltage sensor 33 that detects the voltage across the varistor 11, and a capacitor. A voltage sensor 34 for detecting the voltage across the 13; a current sensor 35 provided between the self-supporting output switching portion 14 and the noise filter 17 on the N1 line side, and a voltage sensor 36 for detecting the voltage across the capacitor 21. It has.

Then, the detection output of each sensor is sent to the control unit 40. Based on this, the control unit 40 controls the opening / closing of the system interconnection opening / closing unit 7, the self-sustaining output opening / closing unit 14, and the auxiliary input opening / closing unit 19.

The control unit 40 is communicably connected to the remote controller device 50 by, for example, the RS485 method. The remote control device 50 has a function of displaying various settings such as an operating state display, various power displays, and an error code display as the power supply device 100.

FIG. 2 is a diagram showing an example of the circuit configuration inside the power conversion unit 2. In the figure, the power conversion unit 2 includes a DC side capacitor 201, a DC / DC converter 2A, an intermediate capacitor 204, and an inverter 2B in order from the DC side. The DC / DC converter 2A includes a first chopper circuit composed of a DC reactor 202, a high-side switching element Q1 and a low-side switching element Q2, a DC reactor 203, a high-side switching element Q3, and a low-side. A second chopper circuit configured by the switching element Q4 of the above is connected in parallel.

The inverter 2B is composed of switching elements Q5, Q6, Q7 and Q8 that form a full bridge circuit.
The switching elements Q1 to Q8 are, for example, IGBTs (Insulated Gate Bipolar Transistors), but may be MOS-FETs (Metal-Oxide-Semiconductor Field Effect Transistors).

As a circuit element for measurement control, a voltage sensor 205 is connected to both ends of the DC side capacitor 201, and the voltage sensor 205 detects an input voltage and sends a detection output to the control unit 40. The current sensors 206 and 207 detect the current flowing through the DC reactors 202 and 203, respectively, and send the detection output to the control unit 40. The voltage sensor 208 connected to both ends of the intermediate capacitor 204 detects the DC link voltage and sends the detected output to the control unit 40. The switching elements Q1 to Q8 are controlled by the control unit 40.

The control unit 40 includes, for example, a computer, and the computer executes software (computer program) to realize a necessary control function. The software is stored in a storage device (not shown) of the control unit 40. The power supply voltage (Vcc) of the control unit 40 can be obtained from, for example, the storage battery 1.

When the storage battery 1 is discharged, the voltage is boosted by the DC / DC converter 2A, and the boosted DC voltage is converted into an AC voltage by the inverter 2B. When charging the storage battery 1, the AC is full-wave rectified by the inverter 2B, and the DC voltage smoothed by the intermediate capacitor 204 is stepped down to a voltage suitable for charging by the DC / DC converter 2A.

《Operation during grid connection》
FIG. 3 is a diagram showing concretely the operation of each opening / closing unit (7, 14, 19p, 19n) at the time of grid connection in the same diagram as in FIG. In the figure, at the time of grid connection, the control unit 40 closes the grid interconnection opening / closing unit 7, and opens the other independent output opening / closing unit 14 and the auxiliary input opening / closing unit 19. In this state, for example, when discharging the storage battery 1, the power conversion unit 2 outputs AC 200V. Therefore, the system connection terminal 12 is provided with a single-phase three-wire output. When charging the storage battery 1, the direction of energy is reversed.

AC 200V is applied to the AC electric circuit 6 at the time of grid connection, but since the self-supporting output opening / closing part 14 and the auxiliary input opening / closing part 19 are all open, the secondary side (upstream side) of each opening / closing part. No AC 200V is applied to. The capacitor 13 is selected so that it can withstand 200 V.

<< Operation during independent operation >>
FIG. 4 is a diagram showing concretely the operation of each opening / closing unit (7, 14, 19p, 19n) at the time of self-sustaining output in the same diagram as in FIG. In the figure, at the time of independent output, the control unit 40 closes the independent output opening / closing unit 14, and opens the other grid interconnection opening / closing unit 7 and the auxiliary input opening / closing unit 19. In this state, the power conversion unit 2 discharges the storage battery 1 and outputs AC 100V. Therefore, the self-supporting output terminal 18 is provided with a single-phase AC 100V.

<< Operation when receiving auxiliary input >>
FIG. 5 is a diagram showing concretely the operation of each opening / closing unit (7, 14, 19p, 19n) at the time of auxiliary input in the same diagram as in FIG. In the figure, there are two types of operations at the time of auxiliary input: (a) an operation of providing an independent output by the auxiliary input and (b) an operation of charging the storage battery 1 by the auxiliary input.

In the case of (a) above, the control unit 40 closes the auxiliary input opening / closing unit 19 and the self-sustaining output opening / closing unit 14, and opens the grid interconnection opening / closing unit 7. The power conversion unit 2 is stopped. In this state, the auxiliary input AC 100V can be provided as an independent output.
In the case of (b) above, although the state is not shown, the control unit 40 closes the auxiliary input opening / closing unit 19, and opens the other grid interconnection opening / closing unit 7 and the self-sustaining output opening / closing unit 14. .. Then, the control unit 40 causes the power conversion unit 2 to perform a conversion operation in the reverse direction, and stores the power of the auxiliary input in the storage battery 1.

<< Welding check before starting power supply operation >>
Each time the control unit 40 starts operation from the state in which the power supply device 100 is stopped, the control unit 40 first checks whether or not welding has occurred in each opening / closing unit. Since the system interconnection opening / closing unit 7 and the self-sustaining output opening / closing unit 14 have a function of outputting a signal at the time of welding, the control unit 40 can perform a welding check depending on the presence or absence of the signal. If it is detected that welding has occurred based on these signals, the control unit 40 displays an error code on the remote controller device 50 and does not operate the power supply device 100. If there is no welding in a normal state, it is confirmed whether or not welding of the remaining one opening / closing part, that is, the auxiliary input opening / closing part 19 has occurred. However, since the auxiliary input opening / closing unit 19 does not have a function of notifying welding by itself, an original check is required. This check will be described in detail below.

FIG. 6 specifically shows the operation of each opening / closing unit (7, 14, 19p, 19n) when the auxiliary input opening / closing unit 19 is welded and there is no auxiliary input in the same diagram as in FIG. It is a figure.
FIG. 7 specifically shows the operation of each opening / closing unit (7, 14, 19p, 19n) when the auxiliary input opening / closing unit 19 is welded and there is an auxiliary input in the same diagram as in FIG. It is a figure.

<< Welding check of opening / closing part for auxiliary input >>
FIG. 8 is a flowchart showing an example of a welding check of the auxiliary input opening / closing unit 19. In the figure, when the operation start operation of the power supply device 100 is performed, the control unit 40 executes the process of this flowchart before the start of operation.

In FIG. 8, the control unit 40 first acquires voltage information of each unit based on the detection outputs of the voltage sensors 32, 33, 34, and 36 (step S1). Next, the control unit 40 determines whether or not the auxiliary input is given from the outside based on the detection output of the voltage sensor 36 (step S2). When there is no auxiliary input, the control unit 40 drives the power conversion unit 2 to output the inspection voltage to the AC electric circuit 6 (step S3). Here, the inspection voltage is a voltage even lower than the voltage at the time of self-sustaining output (second voltage: AC100V), which is lower than the voltage at the time of grid connection (first voltage: AC200V). Specifically, for example, it is a so-called safe voltage of about AC40V, in which a current that is dangerous to the human body does not flow even if a person directly touches the skin.

Here, the voltage of the AC electric circuit 6 (referred to as V1) generated by the output of the power conversion unit 2 can be detected by the voltage sensor 34, and V1≈40V. On the other hand, if the auxiliary input opening / closing unit 19 is normally opened, the voltage (referred to as V2) detected by the voltage sensor 36 is V2 = 0V. Therefore, the voltages of V1 and V2 are clearly different from each other, and it can be seen that the auxiliary input opening / closing portion 19 is normal (no welding) (No in step S4). In this case, the control unit 40 can start the operation (step S8).

On the other hand, when V2≈V1, that is, when the voltage sensor 36 detects a voltage based on the inspection voltage, it is determined that welding has occurred (Yes in step S4), and the control unit 40 is the auxiliary input opening / closing unit. An error code indicating welding of 19 is displayed on the remote controller device 50 (step S5). Then, the control unit 40 stops the operation of the power supply device 100 (step S6). Since the inspection voltage is significantly different from the commonly used voltage (AC200V or AC100V), it can be said that there is virtually no possibility that AC40V is accidentally detected for some reason, resulting in false detection of welding.

On the other hand, when there is an auxiliary input in step S2, the control unit 40 determines whether or not the welding condition is satisfied with the auxiliary input (step S7). Assuming that the auxiliary input opening / closing portion 19 is welded, the voltage V2 detected by the voltage sensor 36 is close to 100V when there is an auxiliary input, and the voltage V1 detected by the voltage sensor 34 is also substantially the same. In a normal state without welding, the voltage V2 detected by the voltage sensor 36 is around 100V when there is an auxiliary input, whereas the voltage V1 detected by the voltage sensor 34 is approximately 0V. Therefore, the welding condition is V2≈V1, and the normal condition is V2 ≠ V1.

If the condition is not satisfied in step S7, the operation is started (step S8), and conversely, if it is satisfied, the control unit 40 causes the remote controller device 50 to display an error code indicating welding of the auxiliary input opening / closing unit 19 (step S5). .. Then, the control unit 40 stops the operation of the power supply device 100 (step S6).

Next, FIG. 9 is a flowchart showing another example of welding check of the auxiliary input opening / closing unit 19. What is performed in this flowchart is a welding check before starting the next operation when the auxiliary input is lost.
First, the control unit 40 starts processing of this flowchart when the voltage sensor 36 stops detecting the auxiliary input while accepting the auxiliary input. Then, the control unit 40 controls to open the auxiliary input opening / closing unit 19 (step S0). If it is normal, the auxiliary input opening / closing portion 19 is opened by this, but if it is welded, it is actually closed even if it should be open under control.

Therefore, the control unit 40 drives the power conversion unit 2 to output the inspection voltage to the AC electric circuit 6 (step S3). Here, the inspection voltage is a voltage even lower than the voltage at the time of self-sustaining output (second voltage: AC100V), which is lower than the voltage at the time of grid connection (first voltage: AC200V). Specifically, for example, it is a safe voltage of about 40 V, in which a current that does not cause a danger to the human body does not flow even if a person directly touches the skin.

Here, the voltage of the AC electric circuit 6 (referred to as V1) generated by the output of the power conversion unit 2 can be detected by the voltage sensor 34, and V1≈40V. On the other hand, if the auxiliary input opening / closing unit 19 is normally opened, the voltage (referred to as V2) detected by the voltage sensor 36 is V2 = 0V. Therefore, the voltages of V1 and V2 are clearly different from each other, and it can be seen that the auxiliary input opening / closing portion 19 is normal (no welding) (No in step S4). In this case, the control unit 40 can start the operation (step S8).

On the other hand, when V2≈V1, that is, when the voltage sensor 36 detects a voltage based on the inspection voltage, it is determined that welding has occurred (Yes in step S4), and the control unit 40 is the auxiliary input opening / closing unit. An error code indicating welding of 19 is displayed on the remote controller device 50 (step S5). Then, the control unit 40 stops the operation of the power supply device 100 (step S6). Since the inspection voltage is significantly different from the commonly used voltage (AC200V or AC100V), it can be said that there is virtually no possibility that AC40V is accidentally detected for some reason, resulting in false detection of welding.

<< Summary >>
In the above power supply device 100, the inverter 2B of the power conversion unit 2 is connected to the inverter 2B of the power conversion unit 2 in a state where the switching unit 7 for grid interconnection, the opening / closing unit 14 for independent output, and the opening / closing unit 19 for auxiliary input are all open. By outputting an inspection voltage that is lower than the self-supporting output voltage (second voltage) and is not used regularly, it is possible to determine whether or not the auxiliary input opening / closing unit 19 is welded. That is, if the auxiliary input opening / closing unit 19 is normally opened, the voltage sensor 36 does not detect the voltage based on the inspection voltage.

On the other hand, when the voltage sensor 36 detects a voltage based on the inspection voltage, it can be determined that the auxiliary input opening / closing unit 19 is welded. In this way, even if the auxiliary input opening / closing unit 19 itself does not have a function of sending a welding signal to the outside, it is possible to determine whether or not the auxiliary input opening / closing unit 19 is welded by verification using the inspection voltage. Further, since the inspection voltage is lower than the self-supporting output voltage, it is possible to prevent damage to the circuit element for 100V and suppress electric shock to the human body. Note that 40V is an example, and a voltage slightly higher than this, or conversely, a lower voltage may be used. However, if it is too low (for example, 10 V or less), it becomes difficult to detect it, and it is difficult for the inverter 2B to output a stable voltage.

<< When welding the opening and closing part for independent output >>
Although the above description has been described only for the welding of the auxiliary input opening / closing unit 19, the same welding check can be performed for the self-supporting output opening / closing unit 14. In this case, the self-supporting output opening / closing unit 14 also has an advantage that an inexpensive opening / closing unit (relay) having no welding detection function can be adopted.

FIG. 10 is a diagram showing a state in which the self-supporting output opening / closing part 14 is welded and the grid interconnection opening / closing part 7 and the auxiliary input opening / closing part 19 are normally opened in the same figure as in FIG. is there. In terms of control, the opening / closing unit 14 for self-sustaining output is also controlled to open, but it is not as controlled due to welding. In this case, since the voltage sensor is not provided on the self-supporting load side as seen from the self-supporting output opening / closing unit 14, welding cannot be detected by voltage comparison. Since both the system interconnection opening / closing unit 7 and the auxiliary input opening / closing unit 19 are open, no voltage is input from the outside.

Therefore, consider using the current sensor 35. Since the noise filter 17 has a built-in capacitor component, a current flows when an AC voltage is applied. Further, a specific load may be connected to the self-supporting output terminal 18. Therefore, when the power conversion unit 2 outputs an inspection voltage of AC40V or a normal AC100V and a current flows through the current sensor 35, the self-supporting output switching unit 14 is welded. If it does not flow in the opposite direction, the self-supporting output opening / closing portion 14 is not welded and is normally opened.

In this way, the welding of the self-supporting output opening / closing portion 14 can be detected in the same manner. That is, when the inverter 2B of the power conversion unit 2 outputs the inspection voltage or the independent output voltage while the independent output opening / closing unit 14 is controlled to open, the current sensor 35 is independent if it does not detect the current. When the output switching unit 14 is normal and the current sensor 35 detects the current due to the current flowing through the capacitance component of the noise filter 17 or the specific load connected to the independent output terminal 18, the independent output switching unit 14 Can be determined to be welded.

<< Supplement >>
It should be noted that the embodiments disclosed this time are exemplary in all respects and are not restrictive. The scope of the present invention is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Storage battery 2 Power converter 2A DC / DC converter 2B Inverter 3 AC reactor 4 AC side capacitor 5 Noise filter 6 AC electric circuit 7 System interconnection switch 8 Condenser 9, 10, 11 Varistor 12 System connection terminal 13 Capacitor 14 Independent output Switch 15 Fuse 16 Varistor 17 Noise filter 18 Self-supporting output terminal 19 (19p, 19n) Auxiliary input switch 20 Noise filter 21 Capacitor 22 Fuse 23 Varistor 24 Auxiliary input terminal 31 Current sensor 32, 33, 34 Voltage sensor 35 Current Sensor 36 Voltage sensor 40 Control unit 50 Remote control device 100 Power supply device 201 DC side capacitor 202, 203 DC reactor 204 Intermediate capacitor 205 Voltage sensor 206, 207 Current sensor 208 Voltage sensor Q1 to Q4 Switching element Q5 to Q8 Switching element

Claims (4)

A power supply unit equipped with an inverter that converts direct current to alternating current or vice versa.
A system connection terminal that is connected to the commercial power system at the first voltage via an AC electric circuit on the AC side of the inverter.
An opening / closing unit for grid interconnection provided between the AC electric circuit and the grid connection terminal,
An independent output terminal that branches off from the AC electric circuit and outputs at a second voltage lower than the first voltage.
An opening / closing portion for independent output provided between the AC electric circuit and the independent output terminal,
Auxiliary input terminal that accepts AC auxiliary input separately from the commercial power system from the outside,
An auxiliary input opening / closing portion provided between the AC electric circuit and the auxiliary input terminal ,
A first voltage sensor for detecting a voltage between two lines of the previous SL auxiliary input for opening and closing portion connecting the auxiliary input terminal,
A control unit having a function of performing switching control of the inverter and a function of determining the presence or absence of welding of the auxiliary input opening / closing unit is provided.
The control unit determines the presence / absence of the auxiliary input based on the detection output of the first voltage sensor, and when it is determined that there is no auxiliary input, the system interconnection opening / closing unit and the self-sustaining output opening / closing unit. In a state where all the auxiliary input opening / closing portions are controlled to be opened, the inverter is made to output an inspection voltage having a predetermined voltage lower than the second voltage , and the first voltage sensor performs the inspection. It detects a voltage based on the use voltage based on whether hawk, determines the presence or absence of welding of the auxiliary input switching unit, the power supply device. Claim 1 in which a noise filter is provided between the self-supporting output terminal and the self-supporting output opening / closing part, and a current sensor for detecting a current flowing between the noise filter and the self-supporting output opening / closing part is provided. The power supply described in. A second voltage sensor for detecting the voltage between the two lines of the AC electric circuit is further provided.
When the control unit determines that the auxiliary input is present, the control unit controls to open the system interconnection opening / closing unit, the self-sustaining output opening / closing unit, and the auxiliary input opening / closing unit, and causes the inverter to open the circuit. The invention according to claim 1 or 2, wherein the presence or absence of welding of the auxiliary input opening / closing portion is determined based on the detection outputs of the first voltage sensor and the second voltage sensor without outputting the inspection voltage. Power supply. Equipped with an inverter, it has a function of grid interconnection with a first voltage via a commercial power system and a grid interconnection switch, and is self-supporting with a second voltage lower than the first voltage via an autonomous output switch. In a power supply device having a function of providing an output and a function of receiving an AC auxiliary input separately from the commercial power system from the outside via an auxiliary input opening / closing unit from the auxiliary input terminal, the control unit of the power supply device. Is a welding judgment method performed by
The opening / closing part for grid interconnection, the opening / closing part for self-sustaining output, and the opening / closing part for auxiliary input are all controlled to be opened, and the auxiliary input is not provided.
In that state, the inverter is made to output an inspection voltage of a predetermined voltage lower than the second voltage.
It is determined whether or not the auxiliary input opening / closing part is welded based on whether or not a voltage based on the inspection voltage is detected between the auxiliary input opening / closing part and the auxiliary input terminal.
Welding judgment method.

Images