Power Conversion Equipment

Abstract

This power conversion device includes: a plurality of switching elements; a drive unit that drives gates with respect to the switching elements; and a control unit that outputs a control signal to the drive unit. The drive unit includes a voltage monitoring unit that, on the basis of the gate resistance connected to a switching element and the gate resistance potential-difference, detects abnormalities in connection with the switching element.

Description

[Technical field]

[0001] The present invention relates to a power conversion device. [Background technology]

[0002] A technology capable of detecting an abnormality relating to a power conversion device is known from Patent Document 1. Patent Document 1 discloses a technology for detecting an abnormality in a braking circuit that passes a current to a braking resistor that consumes energy during a regenerative operation of the power conversion device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-176601 A Summary of the Invention [Problem to be solved by the invention]

[0004] A power conversion device receives AC power, converts it to DC power using a rectifier circuit, and then converts it back to AC using an inverter. The inverter section is often made up of power semiconductors, which are switching elements. The control circuit that controls the power conversion device is an electronic circuit that uses a microcomputer or other ICs, as well as resistors and capacitors. The control circuit components are generally mounted on a circuit board.

[0005] When the output capacity of a power conversion device increases, the capacity of the switching element used must also be increased according to the main capacity. When the capacity of the switching element increases, the package of the switching element also becomes larger. Therefore, it becomes difficult to directly connect the board and the switching element by soldering or the like. Therefore, the board and the switching element are connected via electric wires.

[0006] An abnormality such as a break in the electric wire may occur. In such a case, the power conversion device needs to detect the occurrence of the abnormality.

[0007] Patent Document 1 gives no consideration to such connection abnormalities.

[0008] An object of the present invention is to provide a power conversion device capable of detecting an abnormality in connection with a switching element. [Means for solving the problem]

[0009] The present invention provides a power conversion device having a plurality of switching elements, a drive unit that drives gates of the switching elements, and a control unit that outputs a control signal to the drive unit, The drive unit is The power conversion device includes a gate resistor connected to the switching element, and a voltage monitoring unit that detects an abnormality in connection with the switching element based on a potential difference of the gate resistor. Effect of the Invention

[0010] According to the present invention, an abnormality in the connection with the switching element can be detected. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a circuit diagram of a first embodiment. [Diagram 2] 3 is a timing chart according to the first embodiment. [Diagram 3] 1 is an overall schematic circuit diagram of a power conversion device according to a first embodiment. [Figure 4] 1 is a schematic overall structural diagram of a power conversion device according to a first embodiment of the present invention; [Diagram 5] FIG. 11 is a circuit diagram of a second embodiment. [Figure 6] FIG. 11 is a circuit diagram of a third embodiment. [Figure 7] 11 is a timing chart according to the third embodiment. [Figure 8] FIG. 11 is a circuit diagram of a fourth embodiment. [Figure 9] FIG. 13 is a circuit diagram of a fifth embodiment. [Figure 10]13 is a timing chart according to the fifth embodiment. [Figure 11] FIG. 13 is a circuit diagram of a sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] First, the configuration of the power conversion device to which the present embodiment is applied will be described with reference to Fig. 3 and Fig. 4. Fig. 3 shows an example of the overall circuit configuration of the power conversion device 1 to which the first embodiment is applied.

[0013] In the power conversion device 1, power from an AC power source 2 is full-wave rectified by a diode 3, smoothed by a capacitor 4, and temporarily converted into DC power. The converted DC power is converted into AC power by an inverter of the power conversion device 1. The inverter includes a plurality of IGBTs (Insulated Gate Bipolar Transistors) 5. The IGBTs 5 are switched ON or OFF to convert the DC power into AC power of any frequency and any voltage, and the power conversion device 1 outputs the AC power to a load 6.

[0014] A control circuit 9 that controls the power conversion device 1, an IGBT gate drive circuit 10 that drives the gate of the IGBT 5, and the like are composed of a microcomputer equipped with a CPU, memory, etc., ICs, semiconductors such as transistors, resistors, capacitors, etc. These circuits are mounted on a substrate 8.

[0015] Fig. 4 is a diagram showing an example of the overall structure of a power conversion device to which this embodiment is applied. Power semiconductors such as diodes and IGBTs are often provided in the form of a module sealed in a package. Fig. 4 shows an example in which an IGBT 5 is configured as a module sealed in a package.

[0016] A gate terminal for applying a gate signal is disposed on the IGBT 5. In order to cool the heat generated from the power semiconductors, a plurality of diodes 3 and a plurality of IGBTs 5 are disposed on a cooling fin 21. Each power semiconductor such as the diodes and IGBTs 5 is wired to the capacitor 4 by wiring material 22 such as an electric wire or a copper bar. The plurality of diodes 3 or the plurality of IGBTs 5 are connected by main circuit wiring material 23 such as an electric wire or a copper bar. A terminal of the substrate 8 on which the control circuit 9 and the IGBT gate drive circuit 10 are mounted is connected to the gate terminal of the IGBT 5 by IGBT gate wiring 24 such as an electric wire or a copper bar.

[0017] An operation panel 7 is connected to the control circuit 9. The operation panel 7 inputs operation information for the power conversion device from the outside and outputs information regarding the state of the power conversion device.

[0018] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. EXAMPLES

[0019] FIG. 1 is a diagram showing an IGBT gate drive circuit 10, a control circuit 9, and an IGBT 5 in the first embodiment. In FIG. 1, the IGBT gate drive circuit 10 and the control circuit 9 are mounted on a substrate 8. The IGBT gate drive circuit 10 includes a gate signal amplifier 31, a gate resistor 32, and a voltage monitor 33. An IGBT gate wiring 24 for transmitting a signal for controlling the gate of the IGBT 5 is provided between the substrate 8 and the IGBT 5. The circuit in FIG. 1 shows one phase of the IGBT gate drive circuit 10 and the IGBT 5 shown in FIG. 3, which have a total of six phases.

[0020] A gate signal amplifier 31 amplifies an ON signal or OFF signal, which is a gate source signal from the control circuit 9, to a signal suitable for driving the IGBT gate. The amplified gate control signal is supplied to the gate terminal of the IGBT via a gate resistor 32. A voltage monitor 33 monitors the voltage generated in the gate resistor 32, and monitors whether a voltage pulse is generated immediately after an ON signal is output to the IGBT gate. If a pulse is generated, it is determined to be normal, and if not, it is determined to be abnormal, and a normal or abnormal signal is sent to the upper control circuit 9.

[0021] Next, a description will be given of the operation of the circuit of Example 1. Figure 2 shows a timing chart of the circuit of Figure 1. In Figure 2, the horizontal axis indicates time, and the vertical axis indicates voltage at each point in Figure 1.

[0022] From the top to the bottom of Figure 2, there are shown a gate source signal 41 that turns the gate of the IGBT on or off and is output from the control circuit 9, a gate signal 42 which is the output voltage of the gate signal amplifier 31 which amplifies the gate source signal 41, a voltage (gate voltage) 43 between the gate and emitter of the IGBT, a voltage 44 generated across both ends of the gate resistor 32, and an output voltage (open circuit signal) 45 of the voltage monitor 33.

[0023] At time t1, the gate signal 42 of the gate signal amplifier 31 rises due to an ON signal from the control circuit 9. Here, since the gate of the IGBT is capacitive, the IGBT gate is charged through the gate resistor 32. Therefore, a voltage is generated in the gate resistor 32 during the charging period of the IGBT gate.

[0024] When the IGBT is turned OFF, conversely, discharge occurs from the IGBT gate through the gate resistor 32. This causes a voltage to be generated in the reverse direction. Each time an ON or OFF signal is sent to the IGBT gate, a potential difference is repeatedly generated across the gate resistor.

[0025] At time t2, the IGBT gate wiring 24 between the substrate 8 and the IGBT 5 is broken at the broken point 34 in Fig. 1. In that case, no charge or discharge current flows to the IGBT gate when the IGBT is turned on or off. Therefore, no voltage is generated across the gate resistor.

[0026] Voltage monitor 33 monitors the voltage across the gate resistor immediately after the IGBT is turned on, and if a voltage pulse equal to or greater than a specified value is generated, it does not output signal 45 (outputs an OFF signal). On the other hand, if the voltage across the gate resistor does not exceed the specified value, voltage monitor 33 outputs open circuit signal 45 that is ON. In this manner, if there is no abnormality such as open circuit, voltage monitor 33 is deemed normal and does not output signal 45. If an abnormality such as open circuit occurs, voltage monitor 33 outputs abnormality signal 45, making it possible to detect the abnormality.

[0027] When the control circuit 9 receives the ON signal 45 from the voltage monitor 33, it determines that the IGBT gate wiring 24 between the substrate 8 and the IGBT 5 has been disconnected, and performs control to stop the power conversion device. In this case, the control circuit 9 may control a display unit such as the operation panel 7 to notify the outside that a disconnection has occurred so that a user or administrator can understand.

[0028] According to this embodiment, when an abnormality occurs in the connection of the wiring between the substrate 8 and the IGBT 5, the abnormality can be detected and the operation of the power conversion device can be stopped. EXAMPLES

[0029] 5 is a diagram showing a circuit of the second embodiment. Explanation of points common to the first embodiment will be omitted. This embodiment is an embodiment in which two IGBTs are used in parallel. The reason for using two IGBTs in parallel is that there are cases where it is desired to increase the capacity of the current flowing through the IGBTs.

[0030] Between the gate signal amplifier 31 and the parallel IGBTs, there are provided gate resistors 32 connected to the gates of the respective IGBTs. Each gate resistor 32 is provided with a voltage monitor 33 similar to that of the first embodiment. The output from the voltage monitor 33 is connected to an OR circuit 51, and if any of the voltage monitors 33 detects an abnormality, a detection signal is transmitted to the control circuit 9.

[0031] In this embodiment, two IGBTs are connected in parallel, but the number of parallel connections can be three or more. In this case, a voltage monitor is provided for each gate resistor of each IGBT, and all outputs are ORed.

[0032] When the control circuit 9 receives a signal from the OR circuit 51 indicating that one of the IGBT gate wirings 24 connecting the two IGBTs connected in parallel to the substrate 8 has been broken, the control circuit 9 controls the power conversion device to stop.

[0033] When using two IGBTs in parallel, even if one of the IGBTs has a fault in the IGBT gate signal wiring and is unable to turn on, the IGBT with the healthy wiring can still turn on normally and pass current. In other words, when using two IGBTs in parallel, the situation where one IGBT cannot turn on does not become apparent. As a result, the output of the power conversion device is normal and the abnormality may not become apparent.

[0034] Even under such circumstances, in this embodiment, a wiring defect in the IGBT gate is detected, and the control circuit 9 stops the operation of the power conversion device, thereby making it possible to prevent a secondary failure before it occurs. EXAMPLES

[0035] Fig. 6 is a diagram showing a circuit of the third embodiment. This embodiment is an embodiment in which the voltage monitor 33 in the first embodiment is embodied. In this embodiment, the voltage monitor 33 in Fig. 3 is composed of a voltage comparator 61, an edge detector 62, a latch circuit 63, and an XOR circuit 64. Explanations of points common to the first and second embodiments will be omitted.

[0036] The voltage comparator 61 compares the voltage 44 in the gate resistor 32 with a reference voltage 74. When the voltage 44 in the gate resistor 32 is higher than the reference voltage 74, the voltage comparator 61 outputs an ON signal 71 to the latch circuit 63.

[0037] The reference voltage 74 is preset in the voltage comparator 61. This reference voltage 74 is set to a level lower than the pulse voltage of the voltage 44 of the gate resistor 32 under normal conditions, and is set to a level at which the voltage comparator 61 does not output a signal due to noise, detection errors, etc., except when the IGBT is turned on.

[0038] A signal from the voltage comparator 61 is sent to the input of a latch circuit 63. When an ON signal 71 is input, the latch circuit 63 holds an output signal 73 in an ON state, and when a reset signal 72 is input, the latch circuit 63 is reset and the output signal 73 goes OFF.

[0039] The edge detector 62 detects the falling edge of the gate signal 42 which is the output of the gate signal amplifier 31, and outputs a falling edge signal 72. The latch circuit 63 inputs the falling edge signal (reset signal) 72 from the edge detector 62. An output signal 73 of the latch circuit 63 and the gate signal 42 of the gate drive circuit are input to an XOR circuit 64. The XOR circuit 64 takes an XOR (exclusive OR) of the output signal 73 of the latch circuit 63 and the gate signal 42 which is the output of the gate drive circuit.

[0040] When the gate signal 42 is an ON signal and the output signal 73 of the latch circuit 63 is an ON signal, the output 45 of the XOR circuit 64 is an OFF signal as a normal state. When the gate signal 42 is an ON signal and the output signal 73 of the latch circuit 63 is an OFF signal, the output 45 of the XOR circuit 64 is an ON signal as an abnormality due to a wiring defect.

[0041] The control circuit 9 receives the output signal 45, and if the output signal is an abnormal signal, it detects that a wiring failure has occurred in the IGBT gate, and performs control to stop the operation of the power conversion device.

[0042] Fig. 7 shows a timing chart of the circuit of Fig. 6. In Fig. 7, the horizontal axis shows time, and the vertical axis shows the voltage at each point in Fig. 6.

[0043] From the top to the bottom of Figure 7, there are shown a gate source signal 41 that turns the gate of the IGBT on or off and is output from the control circuit 9, a gate signal 42 which is the output voltage of the gate signal amplifier 31 which amplifies the gate source signal 41, a gate voltage 43 between the gate and emitter of the IGBT, a voltage 44 which is the potential difference across the gate resistor 32, a signal 71 from the voltage comparator 61, a falling signal 72 of the gate signal 42, an output signal 73 from the latch circuit 63, and an output voltage 45 of the XOR circuit 64.

[0044] According to this embodiment, similarly to the first embodiment, when an abnormality occurs in the connection of the wiring between the substrate 8 and the IGBT 5, the abnormality can be detected. Then, the operation of the power conversion device can be stopped. Moreover, the reference voltage 74 for determining whether or not an abnormality has occurred can be set arbitrarily according to the state of the circuit. EXAMPLES

[0045] FIG. 8 is a diagram showing a circuit of the fourth embodiment. The points common to the above-mentioned embodiments will not be described. In this embodiment, a circuit embodying the voltage monitor 33 in the third embodiment is provided for each gate resistor of the IGBT. In FIG. 8, since two IGBTs 5 are connected in parallel, two voltage monitors 33 are connected corresponding to the IGBTs 5. As in the third embodiment, the voltage monitor 33 has a voltage comparator 61, an edge detector 62, a latch circuit 63, and an XOR circuit 64. In FIG. 8, the outputs of the two XOR circuits 64 are connected to an OR circuit 81. The OR circuit 81 outputs the logical sum of the outputs of the two XOR circuits 64 to the control circuit 9. In the case where any of the parallel-connected IGBTs 5 is abnormal due to wiring failure, the control circuit 9 can detect the occurrence of a wiring abnormality by receiving an ON signal.

[0046] According to this embodiment, similarly to the second embodiment, the control circuit 9 can receive from the OR circuit 81 a signal indicating that one of the IGBT gate wirings 24 connecting the two IGBTs connected in parallel to the substrate 8 has been disconnected. Therefore, the power conversion device can be controlled to stop, and a secondary failure can be prevented in advance. EXAMPLES

[0047] FIG. 9 is a diagram showing a circuit of a fifth embodiment. Explanation of points common to the above-mentioned embodiments will be omitted. This embodiment is an embodiment in which a single voltage monitor 93 is provided for each phase when IGBTs are used in parallel. This embodiment differs from the above-mentioned embodiments in that two resistors 921, 922 are provided, which are connected to a gate resistor 91 and connected to each of the IGBTs. A voltage monitor 93 that monitors the voltage generated at the gate resistor 91 is provided for the common gate resistor 91.

[0048] The operation of the circuit of this embodiment will be described. Fig. 10 shows a timing chart of this embodiment. At time t1, when the output voltage of the gate signal amplifier rises due to an ON signal from the control circuit, a potential difference occurs across the gate resistor 91, the first resistor 921, and the second resistor 922, just like in the first embodiment.

[0049] In this embodiment, the gate resistor 91 and the first resistor 921, and the gate resistor 91 and the second resistor 922 are connected in series. Therefore, the voltage generated in the gate resistor 91 is the resistance voltage division ratio. If the IGBT gate wiring 24 is disconnected at the disconnection point 34 at time t2, the resistance voltage division ratio changes and the generated voltage changes.

[0050] The resistance value of the gate resistor 91 is R91, and the resistance values ​​of the first resistor 921 and the second resistor 922 are R92. In this case, the voltage division ratio before and after the IGBT gate wiring 24 is disconnected changes from R91 / (R91+R92 / 2) to R91 / (R91+R92).

[0051] The gate voltage when the IGBT turns ON is VH. In this case, the voltage generated in gate resistor 91 before time t2 is VH×R91 / (R91+R92 / 2). After time t2, voltage 101 generated in gate resistor 91 becomes VH×R91 / (R91+R92), and voltage 101 generated in gate resistor 91 becomes smaller than before the disconnection.

[0052] The reference voltage 102 for voltage detection judgment by the voltage monitor 93 is set to a level at which the IGBT turns ON when the voltage 101 generated by the gate resistor 91 is VH×R91 / (R91+R92 / 2) and does not turn ON when the voltage 101 is VH×R91 / (R91+R92). The voltage monitor 93 detects whether the potential difference generated at turn-on exceeds the reference voltage 102 or not.

[0053] If the potential difference generated when the IGBT 5 is turned on exceeds the reference voltage 102 , the voltage monitor 93 outputs a normal OFF signal 45 to the control circuit 9 .

[0054] If the potential difference across the gate resistor 91 generated when the IGBT 5 is turned on falls below the reference voltage 102 or no potential difference pulse across the gate resistor 91 is generated, the voltage monitor 93 outputs an abnormal ON signal 45 to the control circuit 9.

[0055] According to this embodiment, when IGBTs 5 are used in parallel, a single voltage monitor 93 per phase can be used to determine wiring defects in the IGBT gates. In addition, secondary failures can be prevented. EXAMPLES

[0056] Fig. 11 is a diagram showing a circuit of the fifth embodiment. Explanation of points common to the above-mentioned embodiments will be omitted. This embodiment is an embodiment in which the specific circuit of the voltage monitor 93 in the circuit configuration of Fig. 9 of the fifth embodiment is the circuit of the voltage monitor 33 in the third embodiment.

[0057] 11, the voltage monitor 93 in FIG. 9 is configured with a voltage comparator 61, an edge detector 62, a latch circuit 63, and an XOR circuit 64. In this embodiment, the reference voltage of the voltage comparator 61 is the reference voltage 102, as in the fifth embodiment. In this embodiment, the detection voltage of the voltage comparator is different from that in the third embodiment, but other operations are the same as those in the third embodiment.

[0058] According to this embodiment, when IGBTs 5 are used in parallel, it is not necessary to provide two voltage monitors for each gate resistor of the IGBT, as opposed to the second and fourth embodiments. According to this embodiment, the IGBT has only one gate resistor 91, and only one voltage monitor connected to the single gate resistor 91 is required. This embodiment also makes it possible to determine wiring defects to the gate of the IGBT. In addition, secondary failures can be prevented in advance.

[0059] Furthermore, according to the first to sixth embodiments, damage to components such as IGBTs of the power converter can be prevented and wasteful power consumption can be reduced. Therefore, resources such as components can be effectively utilized and waste can be eliminated, which contributes to the realization of a society that does not adversely affect the global environment through environmental conservation.

[0060] In the above embodiment, an IGBT is used as an example, but it may be replaced with another switching element such as a MOSFET. [Explanation of symbols]

[0061] 1...power conversion device, 2...AC power supply, 3...diode, 4...capacitor, 5...IGBT, 6...load, 7...operation panel, 8...circuit board, 9...control circuit, 10...IGBT gate drive circuit, 21...cooling fin, 22...wiring material, 23...main circuit wiring material, 24...IGBT gate wiring, 31...gate signal amplifier, 32...gate resistor, 33...voltage monitor, 34...disconnection location, 41...gate source signal, 42...gate signal, 43...gate voltage, 44...gate resistor voltage, 45...disconnection signal, 51...OR circuit, 61...voltage comparator, 62...edge detector, 63...latch circuit, 64...XOR circuit, 71...output signal of voltage comparator, 72...output signal of edge detector, 73...output signal of latch circuit, 921...first resistor, 922...second resistor, 102...reference voltage of voltage monitor

Claims

1. A plurality of switching elements; A driving unit that drives a gate of the switching element; A power conversion device having a control unit that outputs a control signal to the drive unit, The drive unit is A gate resistor connected to the switching element; A power conversion device having a voltage monitoring unit that monitors the potential difference of the gate resistor, and determines that there is an abnormality in the connection with the switching element if no voltage pulse is generated immediately after outputting an ON signal to the switching element.

2. 2. The power conversion device according to claim 1, The voltage monitoring unit The power conversion device compares the potential difference with a specified value, and outputs a different signal to the control unit depending on whether or not there is a break in the line between the switching element and the drive unit.

3. 2. The power conversion device according to claim 1, The switching elements are connected in two in parallel, A power conversion device, wherein the gate resistor and the voltage monitoring unit are arranged for each of the switching elements.

4. 2. The power conversion device according to claim 1, The voltage monitoring unit comparing the potential difference with a specified value; The power conversion device outputs a different signal to the control unit depending on the presence or absence of a break in the line between the switching element and the drive unit, based on the signal resulting from the comparison and a signal for controlling a gate.

5. The power conversion device according to claim 4, The switching elements are connected in parallel, A power conversion device in which the gate resistor and the voltage monitoring unit are arranged for each of the switching elements.

6. 2. The power conversion device according to claim 1, The switching element includes a first switching element and a second switching element, a first resistor is disposed between the first switching element and the gate resistor; A power conversion device, comprising: a second resistor disposed between a second switching element and the gate resistor.

7. 7. The power conversion device according to claim 6, The voltage monitoring unit comparing the potential difference with a specified value; Based on the comparison result and the signal that controls the gate, A power conversion device that outputs a different signal to the control unit depending on whether or not there is a break in a line between the switching element and the drive unit.

8. 2. The power conversion device according to claim 1, The power conversion device, wherein the switching element is an IGBT.

9. 2. The power conversion device according to claim 1, an inverter having a plurality of the switching elements; A power conversion device having the drive unit and the control unit.

10. 10. The power converter according to claim 9, The switching element is enclosed in a package, The power conversion device, in which the switching element and the drive unit are connected via wiring.

Images