Power conversion circuit and control system

Abstract

Provided is a power conversion circuit capable of operating while suppressing deterioration in characteristics of a gallium oxide semiconductor. A power conversion circuit includes at least a switching element including a gallium oxide semiconductor, and a control unit that detects a short-circuit state of the switching element and performs an off operation of the switching element on the basis of a detection result, the control unit controls the off operation of the switching element, and the control unit detects a short-circuit state of the switching element and performs an off operation of the switching element on the basis of the detection result. The time from the start of the occurrence of the short circuit to the turn-off operation is less than 1.4 [mu] sec.

Description

Technical Field

[0001] The invention relates to a power conversion circuit and a control system. Background Art

[0002] As a next-generation switching element capable of achieving high withstand voltage, low loss, and high heat resistance, semiconductor devices using gallium oxide (Ga2O3) with a large bandgap have attracted much attention, and are expected to be used in power semiconductor devices such as inverters or converters. In addition, due to the wide bandgap, it is also expected to be used in optical transceivers such as LEDs or sensors. Regarding this gallium oxide, according to non-patent document 1, by mixing with indium and aluminum separately or in combination, the bandgap can be controlled, forming an extremely attractive material system as an InAlGaO-based semiconductor. Here, the so-called InAlGaO-based semiconductor refers to In X Al Y Ga Z O3 (0≤X≤2, 0≤Y≤2, 0≤Z≤2, X+Y+Z=1.5~2.5) can be viewed as the same material system including gallium oxide.

[0003] In addition, Patent Document 1 states that a wide-gap semiconductor element (one or a combination of silicon carbide, gallium nitride, gallium oxide, or diamond) is used in part or all of the diode or switch element in the switch section of the AC-DC converter. However, no research has been conducted on the respective issues of each semiconductor material. In addition, Non-Patent Document 2 states that when annealed at a temperature exceeding 600°C, α-Ga2O3 transforms into β-Ga2O3, the most stable phase.

[0004] Patent Document 1: Japanese Patent Publication No. 2016-27779

[0005] Non-patent document 1: Kentaro Kaneko, "Growth and Properties of Corundum-structured Gallium Oxide Mixed Crystal Thin Films," PhD thesis, Kyoto University, March 2014.

[0006] Non-patent document 2: LEE, Sam-Dong; AKAIWA, Kazuaki; FUJITA, Shizuo, "Thermal stability of single-crystalline α-gallium oxide thin films on sapphire substrates", Physical State Solidi (c), 2013, 10.11: 1592-1595. Summary of the invention

[0007] An object of the present invention is to provide a power conversion circuit capable of operating while effectively utilizing the characteristics of a gallium oxide-based semiconductor.

[0008] The inventors of the present invention have conducted in-depth research to achieve the above-mentioned purpose, and as a result, they believe that the following power conversion circuit can operate the power conversion circuit while suppressing the degradation of the characteristics of the gallium oxide semiconductor contained in the switching element, and found that the power conversion circuit can solve the above-mentioned existing problems. The power conversion circuit has at least a switching element and a control unit that detects the short-circuit state of the switching element and performs a shutdown operation of the switching element based on the detection result, wherein the switching element includes a gallium oxide semiconductor, and the control unit controls the shutdown operation of the switching element so that the time from the occurrence of the short circuit to the execution of the shutdown operation is less than 1.4μsec.

[0009] That is, the present invention relates to the following inventions.

[0010] [1] A power conversion circuit comprising at least a switching element and a control unit for detecting a short-circuit state of the switching element and performing a shutdown operation of the switching element based on the detection result, wherein the switching element comprises a gallium oxide-based semiconductor, and the control unit controls the shutdown operation of the switching element so that the time from the occurrence of the short circuit to the shutdown operation is less than 1.4 μsec.

[0011] [2] A power conversion circuit comprising at least a switching element and a control unit for detecting an abnormal state of the switching element and performing a shutdown operation of the switching element based on the detection result, wherein the switching element includes a gallium oxide-based semiconductor, and the control unit controls the shutdown operation of the switching element so that the gallium oxide-based semiconductor does not undergo a phase change.

[0012] [3] A power conversion circuit comprising at least a switching element and a control unit for detecting an abnormal state of the switching element and performing a shutdown operation of the switching element based on the detection result, wherein the switching element comprises a gallium oxide-based semiconductor, and the control unit controls the shutdown operation of the switching element so that the temperature of the gallium oxide-based semiconductor does not exceed 600°C.

[0013] [4] The power conversion circuit according to any one of [1] to [3] above, wherein the gallium oxide-based semiconductor is a corundum-structured gallium oxide-based semiconductor.

[0014] [5] The power conversion circuit according to [4] above, wherein the corundum structure gallium oxide-based semiconductor includes α-Ga2O3 or a mixed crystal thereof.

[0015] [6] The power conversion circuit according to [4] above, wherein the corundum structure gallium oxide-based semiconductor is α-Ga2O3.

[0016] [7] The power conversion circuit according to [1] above, wherein the control unit controls the shutdown operation so that a time from when a short circuit occurs to when the shutdown operation ends is 0.4 μsec or less.

[0017] [8] The power conversion circuit according to any one of [1] to [3] above, wherein the control unit includes a short-circuit detection circuit.

[0018] [9] The power conversion circuit according to any one of [1] to [3] above, wherein the switching element is a metal oxide semiconductor field effect transistor (MOSFET).

[0019]

[10] A control system comprising: the power conversion circuit according to any one of [1] to [3] above.

[0020] According to the power conversion circuit of the present invention, the circuit can be operated while effectively utilizing the characteristics of the gallium oxide-based semiconductor. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a block diagram showing an example of a control system according to an embodiment of the present invention.

[0022] Figure 2 This is a circuit diagram showing an example of a control system according to an embodiment of the present invention.

[0023] Figure 3 It is a diagram showing an example of an inverter drive device according to an embodiment of the present invention.

[0024] Figure 4 This is a schematic cross-sectional view showing an example of a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) used in the embodiment of the present invention.

[0025] Figure 5 It is a diagram showing a simulation circuit in the embodiment of the present invention.

[0026] Figure 6 FIG. 1 is a diagram showing time changes in the gate voltage during gate voltage control in a simulation.

[0027] Figure 7 It is a figure which shows the result of the simulation performed in the test example.

[0028] Figure 8 It is a diagram showing a timing chart during a short-circuit operation of the inverter drive device according to the embodiment of the present invention. DETAILED DESCRIPTION

[0029] The power conversion circuit in the embodiment of the present invention has at least a switching element, and a control unit that detects the short-circuit state of the switching element and performs a shutdown operation of the switching element based on the detection result, characterized in that the switching element includes a gallium oxide semiconductor, and the control unit controls the shutdown operation of the switching element so that the time from the occurrence of the short circuit to the shutdown operation is less than 1.4μsec. In addition, the power conversion circuit in another embodiment of the present invention has at least a switching element, and a control unit that detects the abnormal state of the switching element and performs a shutdown operation of the switching element based on the detection result, characterized in that the switching element includes a gallium oxide semiconductor, and the control unit controls the shutdown operation of the switching element so that the gallium oxide semiconductor included in the switching element does not undergo a phase change. Furthermore, the power conversion circuit in another embodiment of the present invention has at least a switching element, and a control unit that detects the abnormal state of the switching element and performs a shutdown operation of the switching element based on the detection result, characterized in that the switching element includes a gallium oxide semiconductor, and the control unit controls the shutdown operation of the switching element so that the temperature of the gallium oxide semiconductor does not exceed 600°C.

[0030] The gallium oxide semiconductor (hereinafter also referred to as "semiconductor") is not particularly limited as long as it is a semiconductor containing gallium oxide. The crystal structure of the semiconductor is not particularly limited as long as it does not hinder the purpose of the present invention. As the crystal structure of the semiconductor, for example, a corundum structure, a β-gallium structure, a hexagonal structure (such as an ε-type structure, etc.), an orthorhombic structure (such as a κ-type structure, etc.), a cubic structure or a tetragonal structure, etc. can be cited. In an embodiment of the present invention, the crystal structure of the semiconductor is preferably a corundum structure or a β-gallium structure, and more preferably a corundum structure. In one embodiment of the present invention, even when the semiconductor is in a metastable phase (for example, when it has a corundum structure), the circuit can be operated without the semiconductor undergoing a phase change due to a temperature rise. In this specification, the so-called "phase change temperature" refers to the temperature at which the crystal structure of the semiconductor changes. For example, when the semiconductor is a gallium oxide semiconductor and the crystal structure is a metastable crystal structure (corundum structure, ε-type, κ-type, etc.), the crystal structure of the semiconductor changes to the most stable crystal structure (β-type) at this temperature. When the semiconductor is α-Ga2O3, the phase transition temperature may be, for example, 600°C. When the semiconductor is α-(Al, Ga)2O3, the phase transition temperature may be, for example, 700°C to 1000°C. In addition, the phase transition temperature may also be a temperature obtained by experiment. When the semiconductor has a corundum structure, the semiconductor is not particularly limited as long as it is a semiconductor containing a crystal or mixed crystal of gallium oxide having a corundum structure. In an embodiment of the present invention, when the semiconductor is a mixed crystal, it is preferred that at least gallium oxide containing a corundum structure is contained as a main component. Preferred examples when the semiconductor is a mixed crystal include α-(Al, Ga)2O3, α-(Ir, Ga)2O3, α-(In, Ga)2O3, and the like. Here, the so-called "gallium oxide containing a corundum structure as a main component" means, for example, when the semiconductor is α-(Al, Ga)2O3 (a mixed crystal of α-Ga2O3 and α-Al2O3), as long as the atomic ratio of gallium in all metal elements contained in the semiconductor is 0.5 or more, it will be sufficient. In an embodiment of the present invention, the atomic ratio of gallium in all metal elements contained in the semiconductor is preferably 0.7 or more, more preferably 0.9 or more. In an embodiment of the present invention, preferably, the semiconductor is α-Ga2O3.

[0031] As long as the purpose of the present invention is not hindered, the switching element is not particularly limited and may be a MOSFET or an IGBT. In addition, in an embodiment of the present invention, preferably, the switching element has a return diode. The return diode may be built into the switching element or may be external to the switching element.

[0032] Figure 4 A preferred example of the switching element is shown. Figure 4 The semiconductor device is a metal oxide semiconductor field effect transistor (MOSFET), which includes an n+ type semiconductor layer (drain layer) 1, an n- type semiconductor layer (drift layer) 2, a p+ type semiconductor layer (deep p layer) 6, a p- type semiconductor layer (channel layer) 7, a current dispersion layer 8, an n+ type semiconductor layer (n+ source layer) 11, a gate insulating film 13, a gate electrode 3, a p+ type semiconductor layer 16, a source electrode 24 and a drain electrode 26. In addition, at least a portion of the p+ type semiconductor layer (deep p layer) 6 is buried in the n- type semiconductor layer 2 to a position deeper than the buried lower end portion 3a of the gate electrode 3. In addition, the current dispersion layer 8 is located directly below the gate electrode 3. Figure 4 In the on-state of the semiconductor device, a voltage is applied between the source electrode 24 and the drain electrode 26. When a positive voltage is applied to the gate electrode 3 relative to the source electrode 24, a channel is formed at the interface between the p-type semiconductor layer 7 and the gate insulating film 13, thereby turning on. The off-state is achieved by making the voltage of the gate electrode 3 0V so that a channel cannot be formed, thereby disconnecting.

[0033] In one embodiment of the present invention, the control unit detects the short-circuit state of the switching element, and controls the shutdown operation of the switching element based on the detection result so that the time from the occurrence of the short circuit to the shutdown operation is less than 1.4 μsec. In the embodiment of the present invention, if the time from the occurrence of the short circuit to the shutdown operation (hereinafter, also referred to as "shutdown operation time") is less than 1.4 μsec, the control of the shutdown operation is not particularly limited. In addition, in the embodiment of the present invention, preferably, when the control unit detects the short circuit of the switching element, control is performed so that the time from the occurrence of the short circuit to the shutdown operation is less than 1.4 μsec. In addition, in another embodiment of the present invention, the control unit detects the abnormal state of the switching element, and controls the shutdown operation of the switching element based on the detection result so that the temperature of the semiconductor does not exceed 600°C. The abnormal state refers to a state in which the electrical state or thermal state of the switching element deviates from a predetermined normal state. The detection of the abnormal state is performed using a known method. The control of the shutdown operation is such a control that the shutdown operation control can be performed so that the temperature of the semiconductor does not exceed 600°C. As for the structure of the control circuit, a known structure can be used. As a method for controlling the shutdown operation so that the temperature does not exceed 600°C, more specifically, for example, after performing a simulation related to the temperature rise during a short circuit to calculate the relationship between the temperature rise during a short circuit and time as described later, a method for controlling the shutdown operation to achieve a shutdown operation time that does not exceed 600°C can be cited. In addition, in another embodiment of the present invention, the control unit detects an abnormal state of the switching element and controls the shutdown operation of the switching element based on the detection result so that the semiconductor does not undergo a phase change. In this case, the control of the shutdown operation is to suppress the phase change of the semiconductor by controlling the shutdown operation so that the temperature does not exceed the phase change temperature of the semiconductor. The abnormal state can be a short circuit state, or it can be a state where the temperature of the switching element is above a specific temperature (for example, a temperature about 30°C lower than the phase change temperature). In addition, as long as it does not hinder the purpose of the present invention, the shutdown operation time is not particularly limited. Since the gallium oxide semiconductor has a tendency to have a short temperature rise time when short-circuited as described later, when a short-circuit state is detected and a shutdown operation is performed, the shutdown operation time is generally preferably 1.0 μsec or less. The shutdown operation time is more preferably 0.5 μsec or less, further preferably 0.4 μsec or less, and most preferably 0.3 μsec or less. By setting such a preferred shutdown operation time, the circuit operation freedom can be further improved while suppressing the degradation of the characteristics of the switching element.

[0034] against Figure 4The structure based on MOSFET shown in the figure was used to compare the temperature rise when short-circuiting when SiC was used as the semiconductor material and when Ga2O3 was used as the semiconductor material. The physical property values ​​of SiC and Ga2O3 used in the simulation are shown in Table 1. The simulation circuits are shown in Figure 5 , the time variation of the gate voltage in the gate voltage control is shown in Figure 6 The simulation results show that when Ga2O3 is used, the shutdown operation from short circuit needs to be performed more quickly (at least less than 1.4μsec) than when SiC is used. The fact that gallium oxide semiconductors can reach such a high temperature state during operation (especially during short circuit), and that the temperature rise occurs in such a short time during short circuit, is a new insight obtained through this simulation.

[0035] [Table 1]

[0036] project SiC <![CDATA[Ga2O3]]> Thermal conductivity [W / cm·k] 4.95 0.136 <![CDATA[Heat capacity [J / cm 3 ·k]]]> 2.18 2.92 <![CDATA[Electronic intrinsic mobility [cm 2 / Vs]]]> 860 300 Breakdown electric field strength [MV / cm] 3.0 8.0 <![CDATA[Young's modulus [dyb / cm 2 > <![CDATA[2.3×10 12 ]]> <![CDATA[4.4×10 12 ]]> Poisson's ratio 0.17 0.3 <![CDATA[Coefficient of thermal expansion [K -1 > <![CDATA[3.7×10 -6 ]]> <![CDATA[5.3×10 -6 ]]>

[0037] The simulation results when the drift layer thickness is 3.0 μm, the current spreading layer depth is 1.0 μm, and the deep p layer depth is 1.3 μm are shown in FIG. Figure 7 . Figure 7 The relationship between the time elapsed after the occurrence of a short circuit (from the time the temperature starts to rise) and the temperature when a current spreading layer is applied is shown. Figure 7 It can be seen that in the case of Ga2O3, the temperature reaches 600°C after 0.4μsec from the start of the short circuit. When the temperature of the switching element becomes a high temperature, for example, exceeding 600°C, irreversible degradation will occur at the interface between the semiconductor and the electrode or the MOS interface (when the switching element is a MOSFET). More specifically, as degradation of the interface between the semiconductor and the electrode, for example, migration or oxidation of the electrode metal can be cited. Therefore, especially in the case of using gallium oxide-based semiconductors for the current dispersion layer in the switching element, preferably, the control unit controls the shutdown operation so that the time from the occurrence of the short circuit to the shutdown operation is less than 0.4μsec. In addition, the specific shutdown operation time set can be calculated by simulation based on the applied circuit or device structure, and can also be calculated based on actual operation measurement results, etc.

[0038] The power conversion circuit according to the embodiment of the present invention will be described in more detail below using the accompanying drawings. In addition, there is no particular limitation on the method of the short-circuit detection circuit in the power conversion circuit as long as it does not hinder the purpose of the present invention. As described above, as long as the shutdown operation time can be within the above time, or the shutdown operation can be performed within the range where the temperature of the gallium oxide semiconductor does not exceed 600°C, a circuit structure other than the short-circuit detection circuit shown below may also be used.

[0039] Figure 1 The block diagram of the control system 500 includes a battery (power source) 501, a boost converter 502, a buck converter 503, an inverter 504, a motor (driven object) 505, and a control unit 506. These are mounted on electric vehicles, for example. The battery 501 is composed of a storage battery such as a nickel-metal hydride battery or a lithium-ion battery, and stores power by charging at a power supply station or regenerating energy during deceleration, and can output a DC voltage required for the operation of the driving system or electrical system of the electric vehicle. The boost converter 502 is, for example, a voltage conversion device equipped with a chopper circuit, and can boost a DC voltage of, for example, 200V supplied from the battery 501 to, for example, 650V through the switching operation of the chopper circuit, and output it to the driving system such as the motor. The buck converter 503 is also a voltage conversion device equipped with a chopper circuit, and can output a DC voltage of, for example, 200V supplied from the battery 501 to, for example, about 12V by stepping down the DC voltage to, for example, about 12V, and then output it to the electrical system including the power window, the power steering system, or the on-board electrical equipment.

[0040] The inverter 504 converts the DC voltage supplied from the boost converter 502 into a three-phase AC voltage by switching operation, and outputs it to the motor 505. The motor 505 is a three-phase AC motor constituting the driving system of the electric vehicle, and is rotationally driven by the three-phase AC voltage output from the inverter 504, and its rotational driving force is transmitted to the wheels of the electric vehicle via a transmission, etc., not shown in the figure.

[0041] On the other hand, various sensors not shown are used to measure the actual values ​​of the rotation speed and torque of the wheels, the amount of accelerator pedal depression (acceleration) and the like from the electric vehicle in motion, and these measurement signals are input to the control unit 506. In addition, at the same time, the output voltage value of the inverter 504 is also input to the control unit 506. The control unit 506 has the function of a controller, which has a computing unit such as a central processing unit (CPU) and a data storage unit such as a memory. The control unit 506 generates a control signal by using the input measurement signal and outputs it to the inverter 504 as a feedback signal, thereby controlling the switching operation of the switching element. As a result, the AC voltage provided by the inverter 504 to the motor 505 is instantly corrected, so that the operation control of the electric vehicle can be accurately performed, and the safe and comfortable operation of the electric vehicle can be achieved. In addition, the output voltage to the inverter 504 can also be controlled by providing the feedback signal from the control unit 506 to the boost converter 502. In an embodiment of the present invention, the control unit 506 has a short-circuit detection circuit, which can perform the shutdown operation more quickly, so it is preferred.

[0042] Figure 2 Except Figure 1The circuit structure other than the step-down converter 503 in FIG. 5 is shown, that is, only the circuit structure for driving the motor 505 is shown. The corundum structure gallium oxide-based semiconductor according to the embodiment of the present invention is used, for example, in Figure 2 The switching element 509 is provided. Figure 2 The switch element 509 is an IGBT (insulated gate bipolar transistor), but in the embodiment of the present invention, the switch element may also be a MOSFET. Figure 2 In the circuit, the current is stabilized by placing an inductor (coil, etc.) between the output of the battery 501, and the voltage is stabilized by placing a capacitor (electrolytic capacitor, etc.) between the battery 501, the boost converter 502, and the inverter 504.

[0043] In addition, if Figure 2 As shown by the dotted line, the drive control unit 506 includes a control circuit 507 and a short circuit detection circuit 508. In the control circuit, although not shown, a computing unit and a storage unit composed of a non-volatile memory are provided. The signal input to the control circuit is provided to the computing unit, and a feedback signal is generated by performing necessary operations. In addition, the storage unit temporarily holds the calculation results of the computing unit, or accumulates physical constants and functions required for drive control in the form of a table and outputs them to the computing unit as appropriate. The computing unit and the storage unit can adopt a known structure, and their processing capabilities can also be arbitrarily selected.

[0044] Figure 3 It is used to illustrate Figure 2 A diagram showing an inverter portion and a control unit thereof as an inverter drive device. Figure 3 The inverter drive device is provided with a switching element 102, a freewheeling diode 103 and a control unit 104, and is also provided with a shunt resistor Rshunt, a noise filter 105, an overcurrent detection circuit 106, and a diode D1. The control unit 104 has a drive circuit 107, a comparator 108, a filter circuit 109 and an SR latch circuit 110. Figure 3 , an example is shown in which the switching element 102, the freewheeling diode 103, and the control unit 104 are provided inside the semiconductor module 101, but the embodiment of the present invention is not limited to such a structure.

[0045] The drive circuit 107 drives the switching element 102 according to an input voltage Vin input from the outside through the terminal 111. A MOSFET is used as the switching element 102. The freewheeling diode 103 refluxes current when the switching element 102 is turned off.

[0046] A shunt resistor Rshunt is connected between the source S and GND of the switch element 102. The shunt resistor Rshunt is a current detection unit that generates a voltage signal Ve corresponding to the current flowing through the switch element 102. In addition, as the current detection unit, other current detection units such as a Hall element or a current transformer can also be used instead of the shunt resistor Rshunt. In addition, in the case of the switch element 102 having a current sensing element, the sense current can also be passed through the current detection resistor to detect the current.

[0047] The noise filter 105 is an RC filter including a resistor R1 and a capacitor C1. The noise filter 105 removes noise superimposed on the voltage signal Ve.

[0048] The overcurrent detection circuit 106 includes a comparator 112 and a diode D2. The output voltage Voc of the noise filter 105 is input to the + terminal of the comparator 112. The first threshold value Vref1 is input to the - terminal of the comparator 112. The voltage output from the comparator 112 via the diode D2 is an overcurrent detection signal. That is, when the voltage signal Voc input from the noise filter 105 exceeds the first threshold value Vref1, the overcurrent detection circuit 106 determines that an overcurrent has occurred and outputs an overcurrent detection signal.

[0049] The short circuit detection circuit 113 has a comparator 108, a filter circuit 109, and an SR latch circuit 110. The voltage signal Ve is input to the + terminal of the comparator 108 via the diode D1 and the terminal 114. The overcurrent detection signal is also input to the + terminal of the comparator 108 via the terminal 114. The second threshold value Vref2 is input to the - terminal of the comparator 108. The second threshold value Vref2 is set to a value higher than the first threshold value Vref1. In addition, when an overcurrent is detected, the voltage value of the overcurrent detection signal output from the overcurrent detection circuit 106 is also greater than the second threshold value Vref2. The output voltage A of the comparator 108 is input to the filter circuit 109. The output voltage B of the filter circuit 109 is input to the S terminal of the SR latch circuit 110, and the error signal Fo is output from the Q terminal. Therefore, the short-circuit detection circuit 113 outputs the error signal Fo when the overcurrent detection signal is input from the overcurrent detection circuit 106 or when the voltage signal Ve input without passing through the noise filter 105 exceeds the second threshold value Vref2. In addition, the overcurrent detection signal may be directly input to the filter circuit 109 or the SR latch circuit 110 without passing through the comparator 108. In this case, it is necessary to add a terminal for inputting the overcurrent detection signal from the outside to the inside of the semiconductor module 101.

[0050] The error signal Fo is input to the R terminal of the SR latch circuit and the drive circuit 107, and is output to the outside of the semiconductor module 101 via the terminal 115. Therefore, when the inverter drive device determines that an overcurrent or a short circuit occurs, the error signal Fo is output to the outside of the semiconductor module 101. In addition, when the error signal Fo is input, the drive circuit 107 cuts off the gate signal Vg of the switching element 102 and stops driving the switching element 102.

[0051] Figure 8 It is a diagram showing the timing of the short-circuit operation of the inverter drive device involved in the embodiment of the present invention. Even in the case where a large current flows through the switching element 102 due to abnormal operation of the inverter drive device, noise is generated in the voltage signal Ve just after the current flows, as in normal operation. Afterwards, the voltage signal Ve increases in a manner following the current waveform. Since the responsiveness of the noise filter 105 is low, the time delay for the voltage signal Voc to reach the first threshold value Vref1. On the other hand, since the short-circuit detection circuit 113 detects a short circuit based on the electrical signal Ve input without passing through the noise filter 105, it has excellent responsiveness compared to the overcurrent detection circuit 106 and can quickly detect a short circuit. In addition, the short-circuit cut-off time in the figure is the time from the occurrence of the short circuit to the detection of the short circuit and the cutting off of the gate signal Vg of the switching element 102.

[0052] In addition, in the above-mentioned embodiment, an example of using MOSFET as a switching element is adopted, but IGBT can also be used instead of MOSFET. In addition, the structure of the detection circuit for realizing a specific shutdown operation time (for example, 0.4μsec) is not limited to the above-mentioned embodiment. In an embodiment of the present invention, for example, it is also preferred to use a drive circuit described in Japanese Patent Publication 2021-57976. In addition, in the above-mentioned embodiment, an example of detecting a short circuit state and performing a shutdown operation control on a switching element at high speed based on the detection result is shown, but the present invention is not limited to such an example. For example, a state in which the temperature of the switching element is above a specific temperature can also be detected as an abnormal state, and a shutdown operation is performed on the switching element based on the detection result. The temperature detection of the switching element in this case can be performed using a known structure. For example, a known temperature detection unit (temperature sensor, etc.) is used to detect the temperature of the switching element, and a known control unit is used to control the shutdown operation based on the detection result.

[0053] In addition, as long as it does not hinder the purpose of the present invention, the type of the power conversion circuit is not particularly limited. In the embodiment of the present invention, it can be an AC-AC conversion circuit, a DC-AC conversion circuit, or a DC-DC conversion circuit.

[0054] In addition, of course, multiple embodiments of the present invention may be combined, or some of the constituent elements may be applied to other embodiments. In addition, the number of some constituent elements may be increased or decreased, or further combined with other known technologies. As long as the purpose of the present invention is not hindered, the structure may be changed, such as omitting a part, etc. These also belong to the embodiments of the present invention.

[0055] The power conversion circuit and control system involved in the embodiments of the present invention can be used in all fields such as electronic components / electrical equipment components, optical / electronic photography-related devices, lighting equipment, power supply devices, vehicle-mounted electrical equipment, industrial power conditioners, industrial motors, infrastructure equipment (such as power equipment in buildings and factories, communication equipment, traffic control equipment, water treatment equipment, system equipment, labor-saving equipment, trams, etc.), household appliances (such as refrigerators, washing machines, personal computers, LED lighting equipment, imaging equipment, audio equipment, etc.).

[0056] Explanation of symbols

[0057] 1 n+ type semiconductor layer

[0058] 2 n-type semiconductor layer (drift layer)

[0059] 3. Gate electrode

[0060] 3a Bury the lower end

[0061] 6 p+ type semiconductor layer (deep p layer)

[0062] 7 p-type semiconductor layer (channel layer)

[0063] 8 Current spreading layer

[0064] 11n+ type semiconductor layer

[0065] 13Gate insulating film

[0066] 16p+ semiconductor layer

[0067] 24 Source electrode

[0068] 26 Drain electrode

[0069] 101 Semiconductor Module

[0070] 102 Switching elements

[0071] 103 Freewheel Diode

[0072] 104 Control Department

[0073] 105 Noise Filter

[0074] 106 Overcurrent detection circuit

[0075] 107 drive circuit

[0076] 108 Comparator

[0077] 109 filter circuit

[0078] 110SR latch circuit

[0079] 111 terminal

[0080] 112 Comparator

[0081] 113 short circuit detection circuit

[0082] 114 terminal

[0083] 115 terminal

[0084] 500 control system

[0085] 501 battery (power source)

[0086] 502 Boost Converter

[0087] 503 Buck Converter

[0088] 504 Inverter

[0089] 505 motor (driving object)

[0090] 506 Control Department

[0091] 507 drive circuit

[0092] 508 short circuit detection circuit

[0093] 509 switch element

Claims

1. A power conversion circuit comprising at least a switching element and a control unit for detecting a short-circuit state of the switching element and performing a shutoff operation of the switching element based on the detection result, characterized in that: The switching element includes a gallium oxide-based semiconductor, and the control unit controls an off operation of the switching element so that a time from occurrence of the short circuit to completion of the off operation is less than 1.4 μsec.

2. A power conversion circuit comprising at least a switching element and a control unit for detecting an abnormal state of the switching element and performing a shutoff operation of the switching element based on the detection result, characterized in that: The switching element includes a gallium oxide-based semiconductor, and the control unit controls an off operation of the switching element so that the gallium oxide-based semiconductor does not undergo a phase change.

3. A power conversion circuit comprising at least a switching element and a control unit for detecting an abnormal state of the switching element and performing a shutoff operation of the switching element based on the detection result, characterized in that: The switching element includes a gallium oxide-based semiconductor, and the control unit controls an off operation of the switching element so that a temperature of the gallium oxide-based semiconductor does not exceed 600° C.

4. The power conversion circuit according to any one of claims 1 to 3, wherein: The gallium oxide-based semiconductor is a corundum-structured gallium oxide-based semiconductor.

5. The power conversion circuit according to claim 4, wherein: The corundum structure gallium oxide semiconductor includes α-Ga2O3 or a mixed crystal thereof.

6. The power conversion circuit according to claim 4, wherein: The corundum structure gallium oxide semiconductor is α-Ga2O3.

7. The power conversion circuit according to claim 1, wherein: The control unit controls the shutdown operation so that a time from when a short circuit occurs to when the shutdown operation is completed is 0.4 μsec or less.

8. The power conversion circuit according to any one of claims 1 to 3, wherein: The control unit includes a short-circuit detection circuit.

9. The power conversion circuit according to any one of claims 1 to 3, wherein: The switching element is a metal oxide semiconductor field effect transistor MOSFET.

10. A control system comprising: The power conversion circuit according to any one of claims 1 to 3.

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