Gate drive circuit and control method

Abstract

A gate drive circuit (1) comprises: a drive circuit (10); a transformer (20); a rectifier circuit (30); a voltage clamp element (40); and a control circuit (60). A primary side of the transformer (20) and an output terminal of the drive circuit (10) are connected. A secondary side of the transformer (20) and an input terminal pair of the rectifier circuit (30) are connected. An output terminal pair of the rectifier circuit (30) and a terminal pair of the voltage clamp element (40) are connected. One terminal of the output terminal pair of the rectifier circuit (30) is connected to a gate terminal of a self-excited semiconductor element (50), and the other terminal of the output terminal pair of the rectifier circuit (30) is connected to a reference potential terminal of the self-excited semiconductor element (50). The control circuit (60) controls an amplitude of an output voltage of the drive circuit (10) or a drive frequency of the drive circuit (10) on the basis of current information indicating a current flowing through the drive circuit (10).

Claims

1. A gate drive circuit for driving a self-excited semiconductor element, comprising: a drive circuit; a transformer; a rectifier circuit; a voltage clamp element; and a control circuit, wherein the drive circuit has an oscillator circuit and an amplifier circuit that amplifies the voltage of a signal output from the oscillator circuit, the primary side of the transformer is connected to the output terminal of the amplifier circuit, the secondary side of the transformer is connected to the input terminal pair of the rectifier circuit, the output terminal pair of the rectifier circuit is connected to the terminal pair of the voltage clamp element, one terminal of the output terminal pair of the rectifier circuit is connected to the gate terminal of the self-excited semiconductor element, and the other terminal of the output terminal pair of the rectifier circuit is connected to the reference potential terminal of the self-excited semiconductor element, and the control circuit controls the amplitude of the output voltage of the drive circuit or the drive frequency of the drive circuit based on current information indicating the current flowing through the drive circuit.

2. The gate drive circuit according to claim 1, wherein the control circuit determines whether the gate voltage to the gate terminal has been set, and if it determines that it has been set, controls the amplitude of the output voltage of the drive circuit or the drive frequency of the drive circuit.

3. The gate drive circuit according to claim 2, wherein the control circuit determines that the gate voltage has been set when the current flowing through the drive circuit has been set.

4. The gate drive circuit according to claim 2, wherein the control circuit determines that the gate voltage has been settled after a predetermined time has elapsed after controlling the amplitude of the output voltage of the amplification circuit or after controlling the drive frequency of the drive circuit.

5. The gate drive circuit according to claim 1, wherein the control circuit increases the drive frequency of the drive circuit if the current value indicated by the current information decreases after controlling the drive frequency of the drive circuit, and decreases the drive frequency of the drive circuit if the current value indicated by the current information increases after controlling the drive frequency of the drive circuit.

6. The gate drive circuit according to claim 5, wherein the control circuit controls the drive frequency of the drive circuit until it repeatedly increases and decreases the drive frequency of the drive circuit, and fixes the drive frequency of the drive circuit to the frequency after it has been decreased in the repetition.

7. The gate drive circuit according to claim 5, wherein the control circuit controls the drive frequency of the drive circuit within a range that does not exceed a predetermined upper frequency value.

8. The gate drive circuit according to claim 1, wherein the control circuit controls the amplitude of the output voltage of the drive circuit, and if the increase in the current value indicated by the current information does not exceed a threshold, it increases the amplitude of the output voltage of the drive circuit, and if the increase in the current value indicated by the current information exceeds the threshold, it decreases the amplitude of the output voltage of the drive circuit after controlling the amplitude of the output voltage of the drive circuit.

9. The gate drive circuit according to claim 8, wherein the control circuit controls the amplitude of the output voltage of the drive circuit until it repeatedly increases and decreases the amplitude of the output voltage of the drive circuit, and fixes the amplitude of the output voltage of the drive circuit to the amplitude after it has been decreased in the repeated cycle.

10. The gate drive circuit according to claim 8, wherein the control circuit controls the amplitude of the output voltage of the drive circuit within a range that does not exceed a predetermined upper amplitude value.

11. The gate drive circuit according to any one of claims 1 to 10, wherein the output voltage of the drive circuit is a sine wave.

12. The gate drive circuit according to claim 11, wherein the oscillator circuit outputs a sinusoidal signal.

13. The gate drive circuit according to claim 11, further comprising a bandpass filter provided between the oscillation circuit and the amplification circuit, which transmits the fundamental wave component of the drive frequency of the drive circuit and attenuates the harmonic components.

14. The gate drive circuit according to claim 11, further comprising a bandpass filter provided between the amplification circuit and the primary side of the transformer, which transmits the fundamental wave component of the drive frequency of the drive circuit and attenuates the harmonic components.

15. A control method for a gate drive circuit for driving a self-excited semiconductor element, wherein the gate drive circuit comprises a drive circuit, a transformer, a rectifier circuit, and a voltage clamp element, the drive circuit having an oscillator circuit and an amplifier circuit for amplifying the voltage of a signal output from the oscillator circuit, the primary side of the transformer being connected to the output terminal of the amplifier circuit, the secondary side of the transformer being connected to the input terminal pair of the rectifier circuit, the output terminal pair of the rectifier circuit being connected to the terminal pair of the voltage clamp element, one terminal of the output terminal pair of the rectifier circuit being connected to the gate terminal of the self-excited semiconductor element, and the other terminal of the output terminal pair of the rectifier circuit being connected to the reference potential terminal of the self-excited semiconductor element, the control method comprising: acquiring current information indicating the current flowing through the drive circuit, and controlling the amplitude of the output voltage of the drive circuit or the drive frequency of the drive circuit based on the current information.

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