TW202331282A - power conversion device - Google Patents

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

power conversion device

The present invention relates to a power conversion device.

Patent Document 1 is known as a technology capable of detecting abnormalities related to power conversion devices. Patent Document 1 discloses a technique for detecting an abnormality of a brake circuit that flows current to a brake resistor that consumes energy during a regenerative operation of a power conversion device. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2019-176601

[Problem to be solved by the invention]

A power conversion device receives AC power, converts it into DC power by a rectifier circuit, and converts it into AC power by an inverse converter. The inverter unit is often composed of switching elements, that is, power semiconductors. The control circuit that controls the power conversion device is implemented by a microcomputer, or other IC ((Integrated Circuit: integrated circuit), and an electronic circuit using resistors or capacitors. The components of the control circuit are generally mounted on the substrate.

If the output capacitance of the power conversion device becomes larger, the capacitance of the switching element used according to the main capacitance must also become larger. If the capacitance of the switching element becomes larger, the package of the switching element also becomes larger. Therefore, direct connection with solder or the like becomes difficult between the substrate and the switching element. Therefore, the substrate and the switching element are connected via wires.

There is an abnormal situation such as disconnection of the electric wire. In this case, the power conversion device must detect the occurrence of abnormality.

In Patent Document 1, no consideration is given to the abnormality of such a connection.

An object of the present invention is to provide a power conversion device capable of detecting an abnormality in connection with a switching element. [Technical means to solve the problem]

The present invention is a power conversion device, which includes: a plurality of switching elements; a driving unit that drives the gates of the switching elements; and a control unit that outputs a control signal to the driving unit; The above drive unit has: 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 Invention]

According to the present invention, it is possible to detect an abnormality in connection with a switching element.

First, the configuration of the power conversion device to which this embodiment is applied will be described using FIG. 3 and FIG. 4 . FIG. 3 is an example of the overall circuit configuration of the power conversion device 1 to which the first embodiment is applied.

In the power conversion device 1, the power from the AC power source 2 is full-wave rectified by the diode 3, smoothed by the capacitor 4, and temporarily converted into DC power. The converted DC power is converted into AC power by the inverse converter of the power conversion device 1 . The inverter includes a plurality of IGBTs (Insulated Gate Bipolar Transistor: Insulated Gate Bipolar Transistor) 5 . The power conversion device 1 outputs AC power to the load 6 by switching the IGBT 5 to ON or OFF to convert DC power into AC power of an arbitrary frequency and voltage.

The control circuit 9 for controlling the power conversion device 1, the IGBT gate drive circuit 10 for driving the gate of the IGBT 5, and the like are composed of a microcomputer, IC, and electric circuit equipped with a CPU (Central Processing Unit) or a memory. Semiconductors such as crystals, resistors, capacitors, etc. These circuits are mounted on the substrate 8 .

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 mostly provided in the form of modules enclosed in packages. FIG. 4 shows an example of IGBT5 constituted by a module enclosed in a package.

The IGBT5 is provided with a gate terminal for applying a gate signal. In order to cool the heat generated from the power semiconductor, a plurality of diodes 3 and a plurality of IGBTs 5 are arranged on the cooling fin 21 . Each power semiconductor such as a diode or IGBT 5 and the capacitor 4 are wired by a wiring material 22 such as an electric wire or a copper strip. A plurality of diodes 3 or a plurality of IGBTs 5 are connected by main circuit wiring materials 23 such as electric wires or copper bars. The terminal of the substrate 8 on which the control circuit 9 and the IGBT gate drive circuit 10 are mounted, and the gate terminal of the IGBT 5 are connected by an IGBT gate wiring 24 such as an electric wire or a copper strip.

The operation panel 7 is connected to the control circuit 9 . The operation panel 7 inputs operation information on the power conversion device from the outside, or outputs information related to the state of the power conversion device.

Hereinafter, an embodiment of the present invention will be described in detail using the drawings. [Example 1]

FIG. 1 is a diagram showing the IGBT gate drive circuit 10, the control circuit 9, and the IGBT 5 of the first embodiment. In FIG. 1 , the IGBT gate drive circuit 10 and the control circuit 9 are installed on the 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 the IGBT gate drive circuit 10 shown in FIG. 3 and one of the six phases of the IGBT5.

The gate signal amplifier 31 amplifies the gate source signal from the control circuit 9, that is, the ON signal or the OFF signal, into a signal suitable for driving the IGBT gate. The amplified gate control signal is supplied to the gate terminal of the IGBT through the gate resistor 32 . The voltage monitor 33 monitors the voltage generated in the gate resistor 32, and monitors whether a voltage pulse is generated immediately after the on signal is output to the gate of the IGBT. It is judged as normal when the pulse is generated, and it is judged as abnormal when the pulse is not generated, and a normal or abnormal signal is sent to the upper control circuit 9 .

Next, the operation of the circuit of the first embodiment will be described. FIG. 2 shows a timing diagram of the circuit of FIG. 1 . In FIG. 2 , the horizontal axis shows time, and the vertical axis shows voltages at various parts in FIG. 1 .

From the upper part of Fig. 2 to the lower part, there are gate source signal 41 that turns on or off the gate of the IGBT output from the control circuit 9, and the output voltage of the gate signal amplifier 31 that amplifies the gate source signal 41, i.e. gate Pole signal 42 , voltage between the gate and emitter of IGBT (gate voltage) 43 , voltage 44 generated at both ends of gate resistor 32 , output voltage (disconnection signal) 45 of voltage monitor 33 .

At time t1, according to the ON signal from the control circuit 9, the gate signal 42 of the gate signal amplifier 31 rises. Here, since the gate of the IGBT is very capacitive, the gate resistor 32 is used to charge the gate of the IGBT. Therefore, a voltage is generated at the gate resistor 32 during charging of the IGBT gate.

When the IGBT is turned off, it discharges from the gate of the IGBT via the gate resistor 32 instead. Therefore, a voltage in the opposite direction is generated. Whenever an ON or OFF signal is sent to the IGBT gate, a potential difference is repeatedly generated between the gate resistors.

At time t2, the IGBT gate wiring 24 between the substrate 8 and the IGBT 5 is disconnected at the disconnection portion 34 in FIG. 1 . In this case, when the IGBT is turned on or off, the charge current or discharge current to the gate of the IGBT does not flow. Therefore, no voltage is generated across the gate resistor.

The voltage monitor 33 monitors the voltage between the gate resistors after the IGBT is turned on, and does not output the signal 45 (outputs an off signal) if a voltage pulse exceeding a predetermined value is generated. On the other hand, when the voltage between the gate resistors does not generate a voltage higher than a predetermined value, the voltage monitor 33 outputs a disconnection signal 45 to be turned on. In this way, when there is no abnormality such as a disconnection, the voltage monitor 33 is normal and does not output the signal 45 . When an abnormality such as disconnection occurs, the voltage monitor 33 outputs an abnormal signal 45, so that abnormality can be detected.

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 is disconnected, and controls to stop the power conversion device. In this case, the control circuit 9 may control the display part of the operation panel 7 or the like to notify the outside of the disconnection in a manner that can be grasped by the user or the manager.

According to this embodiment, when a connection abnormality occurs in 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. [Example 2]

FIG. 5 is a diagram showing a circuit of Embodiment 2. FIG. In addition, the description of the points common to the first embodiment will be omitted. This embodiment is an embodiment in the case of using two IGBTs in parallel. The reason for using two IGBTs in parallel is that there are cases where it is desired to obtain the capacity of the current flowing through the IGBTs.

Between the gate signal amplifier 31 and the IGBTs connected in parallel, a gate resistor 32 connected to the gate of each IGBT is provided. A voltage monitor 33 similar to that of the first embodiment is installed on each gate resistor 32 . The output from the voltage monitor 33 is connected to the OR circuit 51, and any one of the voltage monitors 33 is configured to transmit a detection signal to the control circuit 9 when an abnormality is detected.

Although the present embodiment has the case of connecting two IGBTs in parallel, it is not limited to this, and the number of parallel connections may be more than three. The output takes OR.

The control circuit 9 receives a signal from the OR circuit 51 indicating that any one of the IGBT gate wiring 24 connecting the two IGBTs connected in parallel to the substrate 8 is disconnected, and in this case, the power conversion device control by stopping.

In the case of using two IGBTs in parallel, in any IGBT, the IGBT gate signal wiring is bad, and one IGBT cannot be turned on, the IGBT with sound wiring can also be turned on normally and flow current . That is, when two IGBTs are used in parallel, the situation that one IGBT cannot be turned on does not become conspicuous. Therefore, the output as a power conversion device is performed normally, and the abnormality may not become conspicuous.

In this case, in this embodiment, it is also possible to detect faulty wiring of the IGBT gate, and the control circuit 9 stops the operation of the power conversion device to prevent secondary failures. [Example 3]

FIG. 6 is a diagram showing a circuit of Embodiment 3. FIG. In the present embodiment, the voltage monitor 33 of 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 . The points in common with Embodiment 1 or Embodiment 2 are omitted from description.

The voltage comparator 61 compares the voltage 44 of the gate resistor 32 with a reference voltage 74 . When the voltage 44 of 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 .

The reference voltage 74 is preset in the voltage comparator 61 . The 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 where the voltage comparator 61 does not output a signal due to noise or detection error, etc. when the IGBT is turned on. level.

The signal from the voltage comparator 61 is sent to the input of the latch circuit 63 . When the on signal 71 enters the latch circuit 63, the output signal 73 remains on, and when the reset signal 72 enters, the latch circuit 63 resets and the output signal 73 is off.

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

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 normal. 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 of wiring failure.

The control circuit 9 receives the output signal 45, and in the event of an abnormal signal, detects the faulty wiring of the IGBT gate, and the control circuit 9 performs control to stop the operation of the power conversion device.

FIG. 7 shows a timing diagram of the circuit of FIG. 6 . In FIG. 7 , the horizontal axis shows time, and the vertical axis shows voltages at various parts in FIG. 6 .

From the upper part of Fig. 7 to the lower part, it shows that the gate source signal 41 of the gate of the IGBT output by the control circuit 9 is turned on or off, and the output voltage of the gate signal amplifier 31 that amplifies the gate source signal 41 is the gate. Pole signal 42, gate voltage 43 between gate and emitter of IGBT, potential difference of gate resistor 32 is voltage 44, signal 71 from voltage comparator 61, falling signal 72 of gate signal 42, latch circuit 63 The output signal 73, the output voltage 45 of the XOR circuit 64.

According to the present embodiment, as in the first embodiment, when connection abnormality occurs in the wiring between the substrate 8 and the IGBT 5 , the abnormality can be detected. Also, the operation of the power conversion device can be stopped. Also, the reference voltage 74 for determining whether it is abnormal can be set arbitrarily according to the state of the circuit. [Example 4]

FIG. 8 is a diagram showing a circuit of Embodiment 4. FIG. The points common to the above-mentioned embodiments are omitted from description. In this embodiment, a circuit embodying the voltage monitor 33 of the third embodiment is provided according to the gate resistance of each IGBT. In FIG. 8 , since two IGBTs 5 are connected in parallel, two voltage monitors 33 are connected corresponding to the IGBTs 5 . Like 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 . When any one of the IGBTs 5 connected in parallel is abnormal due to faulty wiring, the control circuit 9 can detect the generation of abnormal wiring by receiving the ON signal.

According to this embodiment, as in Embodiment 2, the control circuit 9 can receive a signal from the OR circuit 81 indicating that any one of the IGBT gate wiring 24 connecting the two IGBTs connected in parallel to the substrate 8 is disconnected. . Therefore, it is possible to control the power conversion device so as to stop, and prevent secondary failures before they happen. [Example 5]

FIG. 9 is a diagram showing a circuit of Embodiment 5. FIG. The points common to the above-mentioned embodiments are omitted from description. This embodiment is an embodiment in which the voltage monitor 93 for each phase is realized by one IGBT when the IGBTs are used in parallel. In this embodiment, it is connected to the gate resistor 91 and arranged at a point connected to the two resistors 921 and 922 of each IGBT, which is different from the above-described embodiments. A voltage monitor 93 for monitoring the voltage generated in the gate resistor 91 is installed on the common gate resistor 91 .

The operation of the circuit of this embodiment will be described. FIG. 10 is a timing diagram showing this embodiment. At time t1, according to the turn-on signal from the control circuit, the timing at which the output voltage of the gate signal amplifier rises generates a potential difference between the gate resistor 91, the first resistor 921, and the second resistor 922, as in the embodiment.

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 at the gate resistor 91 becomes the resistor divider ratio. If the IGBT gate wiring 24 is disconnected at the disconnection portion 34 at time t2, the resistance voltage dividing ratio changes and the generated voltage changes.

Let the resistance value of the gate resistor 91 be R91, and the resistance values of the first resistor 921 and the second resistor 922 be R92. In this case, the voltage division ratio changes from R91/(R91+R92/2) to R91/(R91+R92) before and after the disconnection of the IGBT gate wiring 24 .

The gate voltage when the IGBT is turned on is set to VH. In this case, the voltage generated at the gate resistor 91 before time t2 is VH×R91/(R91+R92/2). After time t2, the voltage 101 generated in the gate resistor 91 is VH×R91/(R91+R92), and the voltage 101 generated in the gate resistor 91 becomes smaller than before the disconnection.

The reference voltage 102 for the voltage detection and determination of the voltage monitor 93 is set as the IGBT turn-on level when the generated voltage 101 of the gate resistor 91 is VH×R91/(R91+R92/2), and the generated voltage 101 is When VH×R91/(R91+R92), it is set to the level where the IGBT is not turned on. The voltage monitor 93 detects whether the potential difference generated at turn-on exceeds the reference voltage 102 .

When the potential difference generated when the IGBT 5 is turned on exceeds the reference voltage 102 , the voltage monitor 93 outputs a normal turn-off signal 45 to the control circuit 9 .

When the potential difference of the gate resistor 91 generated when the IGBT 5 is turned on is lower than the reference voltage 102 , or the potential difference pulse of the gate resistor 91 is not generated, the voltage monitor 93 outputs an abnormal ON signal 45 to the control circuit 9 .

According to the present embodiment, when the IGBTs 5 are used in parallel, one of them constitutes the voltage monitor 93 for each phase, and it is possible to judge the faulty wiring of the IGBT gate. Also, secondary failures can be prevented before they happen. [Example 6]

Fig. 11 is a diagram showing a circuit of Embodiment 5. The points common to the above-mentioned embodiments are omitted from description. This embodiment is an embodiment in which the circuit of the voltage monitor 33 in the third embodiment is used as the specific circuit of the voltage monitor 93 in the circuit configuration of the fifth embodiment, that is, FIG. 9 .

In FIG. 11 , the voltage monitor 93 in FIG. 9 is composed of 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 set as the reference voltage 102 in the same manner as in the fifth embodiment. Also, in this embodiment, the detection voltage of the voltage comparator is different from that of the third embodiment, but other operations are the same as those of the third embodiment.

According to this embodiment, when using IGBT5 in parallel, compared with Embodiment 2 or Embodiment 4, it is not necessary to provide two voltage monitors for each of the gate resistance of IGBT. According to this embodiment, there is only one gate resistor 91 of the IGBT, and one voltage monitor connected to one gate resistor 91 is implemented. Furthermore, according to the present embodiment, it is also possible to judge that the wiring leading to the gate of the IGBT is defective. Also, secondary failures can be prevented before they happen.

Furthermore, according to Embodiment 1 to Embodiment 6, damage to components such as IGBTs of the power conversion device can be prevented before they occur, and useless power consumption can be suppressed. Therefore, resources such as parts can be effectively utilized and waste can be eliminated, so it can also contribute to the realization of a society that does not adversely affect the global environment through environmental protection.

In the above-mentioned embodiments, the IGBT is taken as an example for description, and it may also be replaced with other switching elements such as MOSFET (Metal Oxide Semiconductor Field Effect Transistor: Metal Oxide Semiconductor Field Effect Transistor).

1: Power conversion device 2: AC power 3: Diode 4: Capacitor 5:IGBT 6: load 7: Operation panel 8: Substrate 9: Control circuit 10: IGBT gate drive circuit 21: cooling fins 22: Wiring 23: Main circuit wiring material 24: IGBT gate wiring 31:Gate signal amplifier 32: Gate resistor 33: Voltage monitor 34: Broken part 41:Gate source signal 42:Gate signal 43: Gate voltage 44: Voltage of the gate resistor 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: The output signal of the latch circuit 74: Reference voltage 81: OR circuit 91: gate resistance 93: Voltage monitor 101: voltage 102: Reference voltage of voltage monitor 921: the first resistor 922: The second resistor t1: time t2: time VH: voltage

Fig. 1 is the circuit diagram of embodiment 1. FIG. 2 is a timing diagram of Embodiment 1. FIG. FIG. 3 is an overall schematic circuit diagram of the power conversion device as the first embodiment. FIG. 4 is an overall schematic configuration diagram of a power conversion device according to Embodiment 1. FIG. Fig. 5 is the circuit diagram of embodiment 2. Fig. 6 is the circuit diagram of embodiment 3. FIG. 7 is a timing diagram of Embodiment 3. FIG. Fig. 8 is a circuit diagram of Embodiment 4. Fig. 9 is a circuit diagram of Embodiment 5. Fig. 10 is a timing diagram of Embodiment 5. Fig. 11 is a circuit diagram of Embodiment 6.

5:IGBT

8: Substrate

9: Control circuit

10: IGBT gate drive circuit

24: IGBT gate wiring

31:Gate signal amplifier

32: Gate resistor

33: Voltage monitor

34: Broken part

41:Gate source signal

42:Gate signal

43: Gate voltage

44: Voltage of the gate resistor

45: disconnection signal

Claims (10)

A power conversion device comprising: a plurality of switching elements; a drive unit for driving the gate of the switching element; and a control unit that outputs a control signal to the driving unit; and The above drive unit has: a gate resistor connected to said switching element; and A voltage monitoring unit that detects an abnormality in connection with the switching element based on a potential difference between the gate resistors. Such as the power conversion device of claim 1, wherein The voltage monitoring unit compares the potential difference with a predetermined value, and outputs a different signal to the control unit depending on whether there is a disconnection between the switching element and the driving unit. Such as the power conversion device of claim 1, wherein Two of the above switching elements are connected in parallel; and For each of the switching elements, the gate resistor and the voltage monitoring unit are arranged. Such as the power conversion device of claim 1, wherein The voltage monitoring unit compares the potential difference with a predetermined value; and Based on the signal of the comparison result and the signal for controlling the gate, different signals are output to the control unit depending on whether there is a disconnection between the switching element and the drive unit. Such as the power conversion device of claim 4, wherein Two of the above switching elements are connected in parallel; and For each of the switching elements, the gate resistor and the voltage monitoring unit are arranged. Such as the power conversion device of claim 1, wherein As the switching element, there are a first switching element and a second switching element; and A first resistor is arranged between the first switch element and the gate resistor; A second resistor is disposed between the second switching element and the gate resistor. Such as the power conversion device of claim 6, wherein The voltage monitoring unit compares the potential difference with a predetermined value; and Based on the signal of the comparison result and the signal for controlling the gate, different signals are output to the control unit depending on whether there is a disconnection between the switching element and the drive unit. Such as the power conversion device of claim 1, wherein The above switching element is an IGBT. The power conversion device according to claim 1, which has: an inverse converter having a plurality of the above-mentioned switching elements; and The substrate has the above-mentioned driving part and the above-mentioned control part. Such as the power conversion device of claim 9, wherein the switching element described above is enclosed in a package; and The switching element and the drive unit are connected via wiring.