Silicon carbide MOSFET driving voltage control device

Abstract

The utility model relates to the technical field of silicon carbide MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) driving, and particularly provides a silicon carbide MOSFET driving voltage control device, which comprises a driving circuit, a voltage division circuit and a power amplification circuit, the voltage division circuit is respectively connected with a power supply, a grounding wire and the power amplification circuit; the power amplification circuit is respectively connected with a power supply, a grounding wire, the power amplification circuit and a source electrode of the silicon carbide MOSFET; and the driving circuit is respectively connected with a power supply, a grounding wire and a grid electrode of the silicon carbide MOSFET. According to the technical scheme provided by the utility model, a single power supply is divided into two voltages, positive and negative voltages are applied to the grid electrode of the device, the negative voltage can be stabilized when the power supply voltage is too high, the grid-source negative voltage of the device is prevented from being too high, and the positive voltage is stabilized when the power supply voltage is relatively low. When the device is turned on, enough forward voltage is applied to enable the device to be reliably turned on.

Description

Technical Field

[0001] The utility model relates to the technical field of silicon carbide MOSFET driving, in particular to a silicon carbide MOSFET driving voltage control device. Background Art

[0002] Silicon carbide MOSFETs, due to their high voltage resistance, low loss, and high efficiency, have long been considered an "ideal device" and are highly anticipated. Utilizing silicon carbide devices significantly enhances system performance, resulting in compactness, lightweight design, high energy efficiency, and strong driving force. Drivers are the crucial link between silicon carbide devices and low-voltage controllers, primarily enabling the switching of silicon carbide devices and protecting them from various abnormal operating conditions. They are the core component ensuring efficient and reliable operation of power conversion systems, providing high-speed and reliable switching control for power devices and serving as the primary controllable element during transient switching.

[0003] When a sufficiently large forward drive voltage (e.g., +15V) is applied between the gate and source of a SiC MOSFET, the device is turned on, allowing current to flow. When the voltage between the gate and source reaches 0, the device is turned off, blocking the flow of current. In practical applications, when the drain potential of a SiC device changes rapidly, the high du / dt can cause the gate voltage to rise through the junction capacitance, potentially causing the device to be mistakenly turned on. Utility Model Content

[0004] In order to overcome the above-mentioned defects, the present invention proposes a method and device for controlling the driving voltage of a silicon carbide MOSFET.

[0005] In a first aspect, a silicon carbide MOSFET driving voltage control device is provided, wherein the silicon carbide MOSFET driving voltage control device comprises:

[0006] Driving circuit, voltage divider circuit and power amplifier circuit;

[0007] The voltage divider circuit is respectively connected to the power supply, the ground wire and the power amplifier circuit;

[0008] The power amplifier circuit is respectively connected to a power supply, a ground line, the power amplifier circuit and a source of the silicon carbide MOSFET;

[0009] The driving circuit is respectively connected to a power supply, a ground line and a gate of the silicon carbide MOSFET.

[0010] Preferably, the voltage divider circuit includes: a voltage stabilizing diode D1, a resistor R1, a resistor R2, an operational amplifier U1, an operational amplifier U2, a current source I1 and a MOSFET device M1;

[0011] The power supply is connected to the voltage stabilizing diode D1 and the resistor R1 in sequence and then grounded;

[0012] The power supply is connected to the current source I1, the resistor R2 and the source of the MOSFET device M1 in sequence;

[0013] The source of the MOSFET device M1 is grounded;

[0014] The connection point between the voltage stabilizing diode D1 and the resistor R1 is connected to the inverting input terminal of the operational amplifier U1;

[0015] The positive input terminal of the operational amplifier U1 is connected to the drain of the MOSFET device M1;

[0016] The output terminal of the operational amplifier U1 is connected to the gate of the MOSFET device M1;

[0017] The drain of the MOSFET device M1 is connected to the connection point between the current source I1 and the resistor R2 and then connected to the positive input terminal of the operational amplifier U2;

[0018] The inverting input terminal of the operational amplifier U2 is connected to the output terminal of the operational amplifier U2;

[0019] The power supply port of the operational amplifier U2 is connected to the power supply and the ground wire respectively.

[0020] Furthermore, the power amplifier circuit includes: a transistor T1 and a transistor T2;

[0021] The collector of the transistor T1 is connected to a power supply;

[0022] The emitter of the transistor T1 is connected to the emitter of the transistor T2;

[0023] The collector of the transistor T2 is grounded;

[0024] The base of the transistor T1 is connected to the base of the transistor T2;

[0025] The connection point between the base of the transistor T1 and the base of the transistor T2 is connected to the output end of the operational amplifier U2;

[0026] The connection point between the emitter of the transistor T1 and the emitter of the transistor T2 is the output end of the power amplifier circuit.

[0027] Furthermore, the transistor T1 is an NPN transistor, and the transistor T2 is a PNP transistor.

[0028] The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0029] The utility model provides a silicon carbide MOSFET drive voltage control device, comprising: a drive circuit, a voltage divider circuit, and a power amplifier circuit; the voltage divider circuit is respectively connected to a power supply, a ground line, and the power amplifier circuit; the power amplifier circuit is respectively connected to the power supply, the ground line, the power amplifier circuit, and the source of the silicon carbide MOSFET; and the drive circuit is respectively connected to the power supply, the ground line, and the gate of the silicon carbide MOSFET. The drive circuit is capable of outputting a drive voltage to the gate of the silicon carbide MOSFET; the voltage divider circuit and the power amplifier circuit constitute a drive voltage control circuit, capable of outputting an intermediate drive voltage to the source of the silicon carbide MOSFET based on the power supply voltage. This technical solution divides a single power supply into two voltages, enabling the application of positive and negative dual voltages to the device gate. It can stabilize the negative voltage when the power supply voltage is too high, preventing the negative gate-source voltage of the device from being too high, and stabilize the positive voltage when the power supply voltage is low, applying sufficient positive voltage when the device is turned on to ensure reliable device conduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the principle of a silicon carbide MOSFET driving voltage control device according to an embodiment of the present utility model;

[0031] Figure 2 This is a circuit diagram of a silicon carbide MOSFET drive voltage control circuit according to an embodiment of the present utility model. DETAILED DESCRIPTION

[0032] The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings.

[0033] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] Example 1

[0035] See attached Figure 1 , Figure 1 This is a schematic diagram of the principle of a silicon carbide MOSFET driving voltage control device according to an embodiment of the present invention. It includes: a driving circuit, a voltage divider circuit, and a power amplifier circuit;

[0036] The voltage divider circuit is respectively connected to the power supply, the ground wire and the power amplifier circuit;

[0037] The power amplifier circuit is respectively connected to a power supply, a ground line, the power amplifier circuit and a source of the silicon carbide MOSFET;

[0038] The driving circuit is respectively connected to a power supply, a ground line and a gate of the silicon carbide MOSFET.

[0039] In this embodiment, the voltage divider circuit is used to output an intermediate voltage based on the power supply voltage of the power supply;

[0040] The power amplifier circuit is used to perform power amplification on the intermediate voltage to obtain an intermediate driving voltage, and output the intermediate driving voltage to the source of the silicon carbide MOSFET.

[0041] In one embodiment, outputting the intermediate voltage based on the power supply voltage of the power supply includes:

[0042] When the supply voltage exceeds a preset value, stabilizing the output intermediate voltage at a first voltage threshold;

[0043] When the difference between the power supply voltage and the intermediate voltage is lower than a second voltage threshold, the difference between the power supply voltage and the intermediate voltage is stabilized at the second voltage threshold.

[0044] In one embodiment, the preset value is the sum of the first threshold and the second threshold.

[0045] In one embodiment, the first threshold is a stable turn-off voltage of the silicon carbide MOSFET, and the second threshold is a stable turn-on voltage of the silicon carbide MOSFET.

[0046] In a specific embodiment, Figure 1 As shown in the figure, the drive voltage control circuit consists of a voltage divider and a power amplifier circuit. It divides the power supply voltage VCC into two stable voltages and performs power amplification. The intermediate potential VS is connected to the source of the SiC MOSFET. The drive circuit is powered by the power supply voltage, and its output is connected to the gate of the SiC MOSFET. The output voltage rails are VCC and GND. Therefore, the drive voltage for the SiC MOSFET gate-source is VCC-VS when it is turned on, and -VS when it is turned off.

[0047] The voltage divider circuit, powered by VCC, splits VCC into two stable voltages, with the intermediate voltage connected to the power amplifier circuit. When VCC is high, the voltage divider stabilizes VS at the first voltage threshold, ensuring that the negative gate-source voltage does not exceed the safety threshold when the SiC MOSFET is turned off. VCC-VS then varies with changes in VCC. As VCC decreases, if VCC-VS drops to the second voltage threshold, VCC-VS is stabilized at the second voltage threshold, ensuring sufficient positive gate-source voltage when the SiC MOSFET turns on, allowing the device to fully turn on. VS then varies with VCC, at which point VS falls below the first voltage threshold.

[0048] The power amplifier circuit is powered by VCC and is used to make the output terminal VS follow the intermediate voltage divided by the voltage divider circuit and perform power amplification, so that the output terminal VS has a large current output capability. The output terminal VS is connected to the source of the SiC MOSFET.

[0049] In one embodiment, the voltage divider circuit includes: a voltage stabilizing diode D1, a resistor R1, a resistor R2, an operational amplifier U1, an operational amplifier U2, a current source I1, and a MOSFET device M1;

[0050] The power supply is connected to the voltage stabilizing diode D1 and the resistor R1 in sequence and then grounded;

[0051] The power supply is connected to the current source I1, the resistor R2 and the source of the MOSFET device M1 in sequence;

[0052] The source of the MOSFET device M1 is grounded;

[0053] The connection point between the voltage stabilizing diode D1 and the resistor R1 is connected to the inverting input terminal of the operational amplifier U1;

[0054] The positive input terminal of the operational amplifier U1 is connected to the drain of the MOSFET device M1;

[0055] The output terminal of the operational amplifier U1 is connected to the gate of the MOSFET device M1;

[0056] The drain of the MOSFET device M1 is connected to the connection point between the current source I1 and the resistor R2 and then connected to the positive input terminal of the operational amplifier U2;

[0057] The inverting input terminal of the operational amplifier U2 is connected to the output terminal of the operational amplifier U2;

[0058] The power supply port of the operational amplifier U2 is connected to the power supply and the ground wire respectively.

[0059] In one embodiment, the power amplifier circuit includes: a transistor T1 and a transistor T2;

[0060] The collector of the transistor T1 is connected to a power supply;

[0061] The emitter of the transistor T1 is connected to the emitter of the transistor T2;

[0062] The collector of the transistor T2 is grounded;

[0063] The base of the transistor T1 is connected to the base of the transistor T2;

[0064] The connection point between the base of the transistor T1 and the base of the transistor T2 is connected to the output end of the operational amplifier U2;

[0065] The connection point between the emitter of the transistor T1 and the emitter of the transistor T2 is the output end of the power amplifier circuit.

[0066] In one embodiment, the transistor T1 is an NPN transistor, and the transistor T2 is a PNP transistor.

[0067] In a specific embodiment, see Figure 2 This embodiment comprises a Zener diode D1, resistors R1-R2, operational amplifiers U1-U2, a current source I1, a MOSFET M1, and transistors T1-T2. VCC is the power supply voltage, and VS is the output intermediate voltage. The first voltage threshold V1 = I1 * R2 = 5V, and the second voltage threshold is the voltage regulated by Zener diode D1, which is 15V.

[0068] When VCC exceeds 20V, D1 reverses and breaks down, resulting in a voltage of 15V across it. Consequently, the voltage across resistor R1 is VCC - 15V > 5V. Since the voltage across resistor R2 is (I1 - IM1) * R2, where IM1 is the current flowing through MOSFET M1, the maximum voltage across R2 is 5V. At this point, the output of operational amplifier U1 is 0V, M1 is off, and IM1 is 0, resulting in a voltage of 5V across R2. This voltage is output to the power amplifier circuit via the voltage follower formed by operational amplifier U2. The power amplifier circuit consists of NPN transistor T1 and PNP transistor T2. The final output voltage of VS reaches the first voltage threshold of 5V (ignoring the base-emitter voltage of the transistors).

[0069] When VCC is lower than 20V and higher than 15V, D1 experiences reverse breakdown, with the voltage across it reaching 15V. The voltage across resistor R1 then becomes VCC-15V<5V. At this point, the output of operational amplifier U1 causes M1 to operate in its linear region. As current flows through M1, the voltage across R2 drops from 5V to the voltage across R1, reaching a stable state. This voltage passes through the voltage follower and power amplifier circuit, and the final output voltage (VS) equals the voltage across R1 (ignoring the base-emitter voltage of the transistor). VCC-VS represents the second voltage threshold of 15V.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A silicon carbide MOSFET drive voltage control device, characterized in that: The device comprises: a driving circuit, a voltage dividing circuit and a power amplifying circuit; The voltage divider circuit is respectively connected to the power supply, the ground wire and the power amplifier circuit; The power amplifier circuit is respectively connected to a power supply, a ground line, the power amplifier circuit and a source of the silicon carbide MOSFET; The driving circuit is respectively connected to a power supply, a ground line and a gate of the silicon carbide MOSFET.

2. The device according to claim 1, wherein The voltage divider circuit includes: a voltage stabilizing diode D1, a resistor R1, a resistor R2, an operational amplifier U1, an operational amplifier U2, a current source I1 and a MOSFET device M1; The power supply is connected to the voltage stabilizing diode D1 and the resistor R1 in sequence and then grounded; The power supply is connected to the current source I1, the resistor R2 and the source of the MOSFET device M1 in sequence; The source of the MOSFET device M1 is grounded; The connection point between the voltage stabilizing diode D1 and the resistor R1 is connected to the inverting input terminal of the operational amplifier U1; The positive input terminal of the operational amplifier U1 is connected to the drain of the MOSFET device M1; The output terminal of the operational amplifier U1 is connected to the gate of the MOSFET device M1; The drain of the MOSFET device M1 is connected to the connection point between the current source I1 and the resistor R2 and then connected to the positive input terminal of the operational amplifier U2; The inverting input terminal of the operational amplifier U2 is connected to the output terminal of the operational amplifier U2; The power supply port of the operational amplifier U2 is connected to the power supply and the ground wire respectively.

3. The device according to claim 2, wherein The power amplifier circuit includes: a transistor T1 and a transistor T2; The collector of the transistor T1 is connected to a power supply; The emitter of the transistor T1 is connected to the emitter of the transistor T2; The collector of the transistor T2 is grounded; The base of the transistor T1 is connected to the base of the transistor T2; The connection point between the base of the transistor T1 and the base of the transistor T2 is connected to the output end of the operational amplifier U2; The connection point between the emitter of the transistor T1 and the emitter of the transistor T2 is the output end of the power amplifier circuit.

4. The device according to claim 3, characterized in that The transistor T1 is an NPN transistor, and the transistor T2 is a PNP transistor.

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