SiC mosfet drive circuit

Abstract

The technical scheme of the application provides a SiC MOSFET driving circuit, comprising: a first enabling module, outputting a first enabling signal; a second enabling module, outputting a second enabling signal; a driving signal receiving module, receiving a control logic signal of the SiC MOSFET and outputting; a driving voltage output module, providing a driving voltage to a gate of the SiC MOSFET based on the first enabling signal, the second enabling signal and the control logic signal, wherein the first enabling signal is used for enabling or not enabling the start of the driving voltage output module, and the second enabling signal is used for enabling or not enabling the driving voltage output module to output the driving voltage. The SiC MOSFET driving circuit of the technical scheme of the application can have a shorter start delay time and a higher initial driving voltage, and can adjust the driving voltage based on the temperature of the SiC MOSFET driving circuit.

Description

Technical Field

[0001] This application relates to the field of electrical engineering, and more particularly to a SiC MOSFET driving circuit. Background Technology

[0002] Compared to Si MOSFETs and IGBTs, SiC MOSFETs exhibit superior switching performance in high-voltage, high-frequency applications. Driving a SiC MOSFET typically requires an external power supply voltage to provide the necessary drive bias voltage. The higher drive voltage required for SiC MOSFETs compared to Si MOSFETs makes the design of SiC MOSFET drive circuits more challenging.

[0003] SiC MOSFET driver circuits typically feature low-voltage lockout to ensure the drive voltage reaches a safe operating range. For example, for a 20V supply voltage (VDD), the low-voltage lockout level can reach 17V. Once the supply voltage rises from the low voltage to 17V, the SiC MOSFET driver circuit begins operation. The choice of low-voltage lockout level presents a trade-off. A higher low-voltage lockout level produces a good, consistent drive voltage, but it introduces a startup delay to the SiC MOSFET driver circuit, such as delays in protection functions and internal biasing circuitry. Conversely, a lower low-voltage lockout level results in a lower drive voltage for the first few pulses of the control logic signal because it takes time for the supply voltage to rise from the low voltage to the drive voltage required for the MOSFET. Summary of the Invention

[0004] The technical problem to be solved by this application is to optimize the circuit performance of SiC MOSFET driving circuit, so that the SiC MOSFET driving circuit can have both a short start-up delay time and a high initial driving voltage, and the driving voltage can be adaptively adjusted based on the temperature of the SiC MOSFET driving circuit.

[0005] To address the aforementioned technical problems, this application provides a SiC MOSFET driving circuit, comprising: a first enable module configured to receive a supply voltage, compare the supply voltage with a first reference voltage, and output a first enable signal; and a second enable module configured to receive the supply voltage, compare the supply voltage with a second reference voltage, and output a second enable signal, wherein the second reference voltage is greater than the first reference voltage. The second enable module includes: a second reference voltage circuit for providing the second reference voltage, comprising a second high reference voltage circuit, a second low reference voltage circuit, and a third inverter; the second high reference voltage circuit outputs a second high reference voltage and is connected to the second input terminal of a second comparator via a third MOSFET; the second low reference voltage circuit outputs a second low reference voltage and is connected to the second input terminal of the second comparator via a fourth MOSFET. The input terminal of the third inverter is connected to the output terminal of the second comparator, and the output terminal of the third inverter is connected to the gate of the fourth MOSFET. The magnitude of the second low reference voltage output by the second low reference voltage circuit increases with the increase of the temperature of the SiC MOSFET driving circuit. The second comparator includes a first input terminal, a second input terminal, and an output terminal. The first input terminal of the second comparator is used to receive the supply voltage, the second input terminal of the second comparator is connected to the second reference voltage circuit, and the output terminal of the second comparator is used to output the comparison result between the supply voltage and the second reference voltage. The fourth inverter has its input terminal connected to the output terminal of the third inverter, and its output terminal is connected to the driving voltage output module. The driving signal receiving module is configured to receive the SiC... The control logic signal of the MOSFET is output; the drive voltage output module is connected to the first enable module, the second enable module and the drive signal receiving module, and is configured to provide a drive voltage to the gate of the SiC MOSFET based on the first enable signal, the second enable signal and the control logic signal, wherein the first enable signal is used to enable whether the drive voltage output module is started or not, and the second enable signal is used to enable whether the drive voltage output module outputs the drive voltage.

[0006] In some embodiments of this application, when the supply voltage increases to a level not less than the second reference voltage, the second enable signal is an output drive voltage signal.

[0007] In some embodiments of this application, when the supply voltage is less than the second reference voltage, the second enable signal is to not output a drive voltage signal.

[0008] In some embodiments of this application, when the supply voltage increases to a level not less than the first reference voltage, the first enable signal is a start signal.

[0009] In some embodiments of this application, when the supply voltage is less than the first reference voltage, the first enable signal is a non-start signal.

[0010] In some embodiments of this application, the SiC MOSFET driving circuit further includes: an over-temperature protection module; the over-temperature protection module includes a temperature sensing module, which senses the temperature of the SiC MOSFET driving circuit and outputs a sensed voltage positively correlated with the temperature; the second low reference voltage circuit includes a voltage regulation module, which receives the sensed voltage, regulates the sensed voltage, and outputs it, wherein the voltage output by the voltage regulation module is not higher than the voltage output by the second high reference voltage circuit, and not lower than the minimum operating voltage for the SiC MOSFET driving circuit to start.

[0011] In some embodiments of this application, the voltage regulation module includes: a third comparator, the third comparator including a first input terminal, a second input terminal, and an output terminal; a sixth resistor, one end of the sixth resistor connected to the first input terminal of the third comparator, and the other end connected to the temperature sensing module; a seventh resistor, one end of the seventh resistor connected to the second input terminal of the third comparator, and the other end grounded; an eighth resistor, one end of the eighth resistor connected to the second input terminal of the third comparator, and the other end connected to the output terminal of the third comparator; a ninth resistor, one end of the ninth resistor connected to the first input terminal of the third comparator, and the other end connected to the output terminal of the third comparator; a tenth resistor, one end of the tenth resistor connected to the first input terminal of the third comparator, and the other end grounded; and a voltage clamping circuit connected to one end of the ninth and tenth resistors, used to ensure that the output second low reference voltage is not higher than the voltage output by the second high voltage source, and not lower than the minimum operating voltage required to start the SiC MOSFET driving circuit.

[0012] In some embodiments of this application, the voltage clamping circuit includes: a fourth comparator, the first input terminal of which is connected to one end of the ninth resistor and the tenth resistor, the second input terminal of which is connected to the second high reference voltage circuit, and the output terminal of which is used to output a fourth comparison result; a fifth comparator, the first input terminal of which is connected to the second low reference voltage circuit, the second input terminal of which is connected to one end of the ninth resistor and the tenth resistor, and the output terminal of which is used to output a fifth comparison result; and a NOR gate, the first input terminal of which is used to receive the fourth comparison result, the second input terminal of which is used to receive the fifth comparison result, and the output terminal of which outputs... The sixth result: A first switch, one end of which is connected to one end of the ninth resistor and one end of the tenth resistor, and the other end of which is connected to the connection node between the second low reference voltage circuit and the fourth MOS transistor, and the first switch is controlled by the NOR gate; a second switch, one end of which is connected to the second high reference voltage circuit, and the other end of which is connected to the connection node between the second low reference voltage circuit and the fourth MOS transistor, and the second switch is controlled by the fourth comparator; a third switch, one end of which is connected to the second low reference voltage circuit, and the other end of which is connected to the connection node between the second low reference voltage circuit and the fourth MOS transistor, and the third switch is controlled by the fifth comparator.

[0013] In some embodiments of this application, the first enabling module includes: a first reference voltage circuit for providing the first reference voltage; a first comparator including a first input terminal, a second input terminal, and an output terminal, wherein the first input terminal of the first comparator is used to receive the supply voltage, the second input terminal of the first comparator is connected to the first reference voltage circuit, and the output terminal of the first comparator is used to output the comparison result between the supply voltage and the first reference voltage.

[0014] In some embodiments of this application, the first reference voltage circuit includes: a first high reference voltage circuit for providing a first high reference voltage and connected to the second input terminal of the first comparator via a first MOSFET; a first low reference voltage circuit for providing a first low reference voltage and connected to the second input terminal of the first comparator via a second MOSFET; a first inverter, the input terminal of the first inverter being connected to the output terminal of the first comparator and the gate of the second MOSFET, and the output terminal of the first inverter being connected to the gate of the first MOSFET; the first enable module further includes a second inverter, the input terminal of the second inverter being connected to the output terminal of the first inverter, and the output terminal of the second inverter being connected to the drive voltage output module.

[0015] In some embodiments of this application, the SiC MOSFET driving circuit further includes: a protection logic module for detecting abnormal conditions of the SiC MOSFET driving circuit and outputting detection results; a first AND gate, including a first input terminal, a second input terminal and an output terminal, wherein the first input terminal of the first AND gate is used to receive the first enable signal, the second input terminal of the first AND gate is used to receive the detection results, and the output terminal of the first AND gate is connected to the driving voltage output module.

[0016] In some embodiments of this application, the protection logic module includes: an over-temperature protection module for detecting whether the SiC MOSFET driving circuit has an over-temperature condition and outputting a temperature detection result; an over-current protection module for detecting whether the SiC MOSFET driving circuit has an over-current condition and outputting a current detection result; and a second AND gate, including a first input terminal, a second input terminal, and an output terminal, wherein the first input terminal of the second AND gate is connected to the over-temperature protection module, the second input terminal of the second AND gate is connected to the over-current protection module, and the output terminal of the second AND gate is connected to the second input terminal of the first AND gate.

[0017] In some embodiments of this application, the drive voltage output module includes: a third AND gate, including a first input terminal, a second input terminal, a third input terminal, and an output terminal, wherein the first input terminal of the third AND gate is used to receive a first enable signal from the first enable module, the second input terminal of the third AND gate is used to receive a second enable signal from the second enable module, and the third input terminal of the third AND gate is connected to the drive signal receiving module; and a buffer circuit, wherein the input terminal of the buffer circuit is connected to the output terminal of the third AND gate, and the output terminal of the buffer circuit is connected to the gate of the SiC MOSFET.

[0018] The SiC MOSFET driving circuit of this application enables the drive voltage output module to start or not through a first enable signal output from a first enable module, and enables the drive voltage output module to output a drive voltage through a second enable signal output from a second enable module. This solves the problem that existing SiC MOSFET driving circuits cannot simultaneously achieve a short start-up delay time and a high initial drive voltage. Simultaneously, the magnitude of the second low reference voltage output by the second low reference voltage source circuit increases with the temperature of the SiC MOSFET driving circuit, thereby dynamically adjusting the hysteresis value of the second enable module. This improves the problem of potentially low gate voltage of the SiC MOSFET at higher temperatures, thereby reducing conduction losses, reducing thermal effects, improving the safety of the SiC MOSFET, and increasing the energy conversion capability of the SiC MOSFET. These effects are achieved through a reasonable circuit design. Attached Figure Description

[0019] The following accompanying drawings describe in detail the exemplary embodiments disclosed in this application. The same reference numerals denote similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting and exemplary, and the drawings are for illustrative purposes only and are not intended to limit the scope of this application. Other embodiments may similarly fulfill the inventive intent of this application. It should be understood that the drawings are not drawn to scale. Wherein:

[0020] Figure 1 This is a schematic diagram of the SiC MOSFET driving circuit according to an embodiment of this application;

[0021] Figure 2 This is a schematic diagram of the circuit structure of the first enabling module according to an embodiment of this application;

[0022] Figure 3 This is a schematic diagram of the circuit structure of the first high reference voltage circuit and the first low reference voltage circuit according to an embodiment of this application;

[0023] Figure 4 This is a schematic diagram of the circuit structure of the second enabling module according to an embodiment of this application;

[0024] Figure 5 This is a schematic diagram of the circuit structure of the voltage regulation module according to an embodiment of this application;

[0025] Figure 6 This is a schematic diagram of the circuit structure of the voltage clamping circuit in an embodiment of this application;

[0026] Figure 7 The voltage V in this application embodiment A The curves showing the changes in voltage Vout1, voltage Vout2, voltage Vout3, and voltage Vc;

[0027] Figure 8 This is a schematic diagram of the circuit structure of the protection logic module and the first AND gate in an embodiment of this application;

[0028] Figure 9 This is a schematic diagram of the circuit structure of the drive voltage output module according to an embodiment of this application. Detailed Implementation

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0030] The terminology used in this application is for the purpose of describing particular exemplary embodiments only and is not restrictive. For example, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” used herein may also include the plural forms. It should be understood that although the terms first, second, third, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Thus, a first element in some embodiments may be referred to as a second element in other embodiments without departing from the teachings of this application. The same reference numerals or the same reference signs denote the same elements throughout the specification. When used in this specification, the terms “comprising,” “including,” and / or “containing” mean that the associated integers, steps, operations, elements, and / or components are present, but do not exclude the presence of one or more other features, integers, steps, operations, elements, components, and / or groups, or the possibility of adding other features, integers, steps, operations, elements, components, and / or groups to the system / method. When different components are described as being associated in this specification, the relationship may be direct or indirect. For example, "A and B are connected" can mean that A and B are directly connected, or that A and B are indirectly connected through other components.

[0031] Considering the following description, the features and other features disclosed in this specification, as well as the operation and function of the related elements of the structure, and the economy of the combination and manufacture of components, can be significantly improved. All of these form part of this specification disclosure, with reference to the accompanying drawings. However, it should be clearly understood that the drawings are for illustrative and descriptive purposes only and are not intended to limit the scope of this specification disclosure. Flowcharts are used in this application to illustrate the operations performed by the system according to embodiments of this application.

[0032] The following description provides specific application scenarios and requirements for this application, intended to enable those skilled in the art to make and use the content of this application. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this application. Therefore, this application is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.

[0033] refer to Figure 1 The SiC MOSFET driving circuit of this application embodiment can provide a driving voltage to the SiC MOSFET, which can be an N-type SiC MOSFET or a P-type SiC MOSFET. The figure illustrates an N-type SiC MOSFET as an example. The SiC MOSFET driving circuit includes a first enable module, a second enable module, a drive signal receiving module, and a drive voltage output module. The first enable module can receive a supply voltage VDD, which gradually increases in magnitude. For example, in some embodiments, the supply voltage gradually increases from 0V to 20V.

[0034] The first enabling module compares the supply voltage VDD with a first reference voltage and outputs a first enabling signal. This first enabling signal enables or disables the drive voltage output module. The first enabling module can be connected to the a-interface of the drive voltage output module. When the supply voltage VDD increases to a level not less than the first reference voltage, the first enabling signal is a startup signal, indicating that the module receiving the signal is preparing to power on and that its basic functions are in place. When the supply voltage VDD is less than the first reference voltage, the first enabling signal is a non-start signal, indicating that the module receiving the signal does not perform any operation. In other words, when the supply voltage VDD increases to a level not less than the first reference voltage, the start signal output by the first enable module prepares the drive voltage output module for power-on to output the drive voltage, and enables the basic functions of the drive voltage output module to be in place. At this time, the drive voltage output module cannot yet output the drive voltage. The basic functions being in place include each functional module obtaining the corresponding supply voltage, each detection circuit (such as a temperature sensing module, a current sensing module, etc.) having its functions activated, and detection-based protection function modules (such as an over-temperature protection module, an over-current protection module, etc.) also having been activated. The first enable module in this embodiment can enable the detection and protection functions as early as possible, so that when an abnormal situation occurs in the SiC MOSFET drive circuit, the protection mechanism can respond as early as possible.

[0035] The second enabling module is configured to receive the supply voltage VDD, compare the supply voltage VDD with a second reference voltage, and output a second enabling signal, wherein the second reference voltage is greater than the first reference voltage. The second enabling module can be connected to the b interface of the drive voltage output module. When the supply voltage VDD increases to a level not less than the second reference voltage, the second enabling signal is an output drive voltage signal, which means that the module receiving the signal starts executing the operation of outputting the drive voltage. When the supply voltage VDD is less than the second reference voltage, the second enabling signal is a no-output drive voltage signal, which means that the module receiving the signal is prohibited from outputting the drive voltage. In this embodiment, the second enabling signal is used to enable whether the drive voltage output module outputs the drive voltage.

[0036] The drive signal receiving module is configured to receive and output the control logic signal of the SiC MOSFET. The drive signal receiving module can be a known circuit structure, as long as it can achieve the corresponding function. The drive voltage output module is connected to the first enable module, the second enable module, and the drive signal receiving module, and is configured to provide a drive voltage to the gate of the SiC MOSFET based on the first enable signal, the second enable signal, and the control logic signal.

[0037] The second reference voltage of the second enabling module should be greater than the first reference voltage of the first enabling module. For example, if the supply voltage VDD gradually increases from 0V to 20V, the first reference voltage is 16V, and the second reference voltage is 18V. When the supply voltage VDD gradually increases from 0V but is less than the first reference voltage (first stage), it indicates that the supply voltage VDD is too small. In this case, the first enabling module sends a non-start signal to the drive voltage output module, and the second enabling module sends a non-output drive voltage signal to the drive voltage output module. At this time, the drive voltage output module has not yet started working; it neither prepares for power-on nor outputs drive voltage. This avoids the problem of excessively high on-resistance of the SiC MOSFET due to an excessively small supply voltage VDD, causing overheating of the SiC MOSFET and ultimately burning it out. When the supply voltage VDD increases to a level not less than the first reference voltage but less than the second reference voltage (second stage), the first enabling module sends a start signal to the drive voltage output module, and the second enabling module sends a signal not to output drive voltage to the drive voltage output module. At this time, the drive voltage output module only prepares for power-on but does not output drive voltage. This stage allows the SiC MOSFET drive circuit to start in a timely manner with a short start-up delay time. When the supply voltage VDD continues to increase to the second reference voltage (third stage), the first enabling module sends a start signal to the drive voltage output module, and the second enabling module sends an output drive voltage signal to the drive voltage output module. Since the drive voltage output module has already started in the second stage, once it receives the output drive voltage signal, it does not need to go through the start-up stage again and directly performs the operation of outputting drive voltage. At the same time, since the supply voltage VDD has climbed to a sufficiently high level, the initial drive voltage output by the drive voltage output module is relatively high. It should be noted that during the process of the power supply voltage VDD rising, the drive signal receiving module can continuously receive and output the control logic signal of the SiC MOSFET, thereby enabling the SiC MOSFET drive circuit of this embodiment to have both a short startup delay time and a high initial drive voltage.

[0038] refer to Figure 2The first enabling module may include a first reference voltage circuit and a first comparator D1. The first reference voltage circuit is used to provide a first reference voltage. The first comparator D1 includes a first input terminal (e.g., positive terminal), a second input terminal (e.g., negative terminal), and an output terminal. The first input terminal of the first comparator D1 is used to receive the supply voltage VDD. The second input terminal of the first comparator D1 is connected to the first reference voltage circuit. The output terminal of the first comparator D1 is used to output the comparison result between the supply voltage VDD and the first reference voltage.

[0039] In some embodiments, the first reference voltage circuit may include a first high reference voltage circuit, a first low reference voltage circuit, and a first inverter F1. The first high reference voltage circuit provides a first high reference voltage V1-H and is connected to the second input terminal of the first comparator D1 via a first MOSFET M1. The first low reference voltage circuit provides a first low reference voltage V1-L and is connected to the second input terminal of the first comparator M1 via a second MOSFET M2. The input terminal of the first inverter F1 is connected to the output terminal of the first comparator D1 and the gate of the second MOSFET M2, and the output terminal of the first inverter F1 is connected to the gate of the first MOSFET M1. The first enable module further includes a second inverter F2. The input terminal of the second inverter F2 is connected to the output terminal of the first inverter F1, and the output terminal of the second inverter F2 is connected to the drive voltage output module, for example, to interface a of the drive voltage output module. The first high reference voltage circuit and the first low reference voltage circuit can respectively provide a first high reference voltage V1-H and a first low reference voltage V1-L with relatively fixed values, wherein the voltage of the first high reference voltage V1-H is, for example, 16V, and the voltage of the first low reference voltage V1-L is, for example, 14V.

[0040] When the first MOSFET M1 is turned on and the second MOSFET M2 is turned off, if the supply voltage VDD is less than the voltage output by the first high reference voltage V1-H, then the output of the first comparator D1 is low, the output of the first inverter F1 is high, and the output of the second inverter F2 is low. At this time, the second MOSFET M2 remains off, and the first MOSFET M1 remains on. The first enable signal sent to the drive voltage output module is a non-start signal. When the supply voltage VDD increases to a level not less than the first high reference voltage V1-H, the first comparator D1 outputs a high level, the output of the first inverter F1 is low, and the output of the second inverter F2 is high. Then, the second MOSFET M2 turns on, and the first MOSFET M1 turns off. At this time, the first enable signal sent to the drive voltage output module is a start signal.

[0041] Figure 3 The diagram shows circuit diagrams of the first high reference voltage circuit and the first low reference voltage circuit. The internal power supply module in the diagram is mainly used to provide stable operating voltages to various modules within the SiC MOSFET drive circuit. For example, the internal power supply module can provide the required and stable operating voltages to the drive voltage output module, protection logic module, etc. The internal power supply module receives the supply voltage VDD, converts it to the required voltage magnitude, and outputs it. Then, it is divided by a resistor array to provide the required first high reference voltage V1-H and first low reference voltage V1-L. The specific circuit of the resistor array is designed according to the required magnitudes of the first high reference voltage V1-H and first low reference voltage V1-L. Specifically, the number of resistors connected between resistors R11 and R1n, between resistors R1n and R1(n+1), between R1(n+1) and R1(n+2), and between R1(n+2) and R1(2n+2) can be determined according to actual conditions.

[0042] refer to Figure 4 The second enabling module includes a second reference voltage circuit, a second comparator D2, and a fourth inverter F4. The second reference voltage circuit is used to provide the second reference voltage. The second comparator D2 includes a first input terminal (e.g., the positive terminal), a second input terminal (e.g., the negative terminal), and an output terminal. The first input terminal of the second comparator D2 is used to receive the supply voltage VDD. The second input terminal of the second comparator D2 is connected to the second reference voltage circuit. The output terminal of the second comparator D2 is used to output the comparison result between the supply voltage VDD and the second reference voltage.

[0043] The second reference voltage circuit includes a second high reference voltage circuit, a second low reference voltage circuit, and a third inverter F3. The second high reference voltage circuit outputs a second high reference voltage V2-H and is connected to the second input terminal of the second comparator D2 via a third MOSFET M3. The second low reference voltage circuit outputs a second low reference voltage V2-L and is connected to the second input terminal of the second comparator D2 via a fourth MOSFET M4. A connection node c exists between the second low reference voltage circuit and the fourth MOSFET M4. The input terminal of the third inverter F3 is connected to the output terminal of the second comparator D2, and the output terminal of the third inverter F3 is connected to the gate of the fourth MOSFET M4. The input terminal of the fourth inverter F4 is connected to the output terminal of the third inverter F3, and the output terminal of the fourth inverter F4 is connected to the drive voltage output module, for example, to interface b of the drive voltage output module.

[0044] When the third MOSFET M3 is turned on and the fourth MOSFET M4 is turned off, if the supply voltage VDD is less than the second high reference voltage V2-H, the output of the second comparator D2 is low, the output of the third inverter F3 is high, and the output of the fourth inverter F4 is low. At this time, the fourth MOSFET M4 remains off, and the third MOSFET M3 remains on. The second enable signal sent to the drive voltage output module is to not output a drive voltage signal. When the supply voltage VDD increases to a level not less than the second high reference voltage V2-H, the output of the second comparator D2 is high, the output of the third inverter F3 is low, and the output of the fourth inverter F4 is high. Then, the fourth MOSFET M4 is turned on, and the third MOSFET M3 is turned off. At this time, the second enable signal sent to the drive voltage output module is to output a drive voltage signal.

[0045] The second high reference voltage circuit can provide a relatively fixed second high reference voltage V2-H, for example, 18V. The second low reference voltage circuit provides a relatively variable second low reference voltage V2-L, which increases with the temperature of the SiC MOSFET drive circuit. When the SiC MOSFET temperature is too high, the difference between the second high reference voltage V2-H and the second low reference voltage V2-L can be reduced by increasing the magnitude of the second low reference voltage V2-L, i.e., reducing the hysteresis of the second enable module. This increases the drive voltage of the SiC MOSFET, thereby reducing the on-resistance (Rdson) of the SiC MOSFET and mitigating the thermal effects during SiC MOSFET operation.

[0046] Continue to refer to Figure 4 In this embodiment, the second low reference voltage V2-L is implemented using an analog circuit to change with the temperature of the SiC MOSFET. The temperature sensing module in the figure is from the over-temperature protection (OTP) module in the SiC MOSFET driving circuit. This temperature sensing module can sense the temperature of the SiC MOSFET driving circuit and output a induced voltage positively correlated with the temperature. The voltage regulation module is a module in the second low reference voltage circuit, used to receive the induced voltage, regulate it, and then output it. Ultimately, the voltage output by the voltage regulation module should not be higher than the second high reference voltage V2-H output by the second high reference voltage circuit, and should not be lower than the minimum operating voltage required for the SiC MOSFET driving circuit to start.

[0047] refer to Figure 5In some embodiments, the voltage regulation module may include a third comparator D3, the first input terminal (e.g., the positive terminal) of the third comparator D3 being connected to one end of a sixth resistor R6, and the other end of the sixth resistor R6 being connected to the temperature sensing module. The second input terminal (e.g., the negative terminal) of the third comparator D3 is connected to one end of a seventh resistor R7 and an eighth resistor R8, the other end of the seventh resistor R7 being grounded, and the other end of the eighth resistor R8 being connected to the output terminal of the third comparator D3. One end of a ninth resistor R9 is connected to the first input terminal of the third comparator D3, and the other end of the ninth resistor R9 is connected to the output terminal of the third comparator D3. One end of a tenth resistor R10 is connected to the first input terminal of the third comparator D3, and the other end of the tenth resistor R10 is grounded. The voltage regulation module also includes a voltage clamping circuit, which is connected to one end of the ninth resistor R9 and the tenth resistor R10, and is capable of clamping the output second low reference voltage V2-L within a range that is not higher than the second high reference voltage V2-H and not lower than the minimum operating voltage required for the SiC MOSFET drive circuit to start.

[0048] refer to Figure 6 The voltage clamping circuit may include a fourth comparator D4, a fifth comparator D5, and a NOR gate. The first input terminal (e.g., the positive terminal) of the fourth comparator D4 is connected to one end of the ninth resistor R9 and the tenth resistor R10, assuming it is connected to node A in the figure. The second input terminal (e.g., the negative terminal) of the fourth comparator D4 is connected to the second high reference voltage circuit to receive the second high reference voltage V2-H output by the second high reference voltage circuit. The fourth comparator D4 compares the voltage V at node A... A The fifth comparator D5 compares the magnitude of the second high reference voltage V2-H with the voltage Vout1 at node A. The first input (e.g., the positive terminal) of the fifth comparator D5 is connected to the second low reference voltage circuit to receive the second low reference voltage V2-L output by the second low reference voltage circuit. The second input (e.g., the negative terminal) of the fifth comparator D5 is connected to node A, and the fifth comparator D5 compares the second low reference voltage V2-L with the voltage Vout1 at node A. AThe second high reference voltage circuit is connected to node c via a second switch S2, which is controlled by the voltage Vout1. The second low reference voltage circuit is connected to node c via a third switch S3, which is controlled by the voltage Vout2. The voltage across the tenth resistor R10 serves as the output voltage of the third comparator D3, providing node C with a temperature-dependent voltage value. Combined with the opening and closing of the first switch S1, the second switch S2, and the third switch S3, the preset clamping function is achieved.

[0049] Figure 7 The voltage V is shown A The voltage variation curves of Vout1, Vout2, Vout3, and the voltage Vc at node c are shown in Table 1. A The corresponding voltage Vc.

[0050] Table 1 Different voltages V A The corresponding voltage Vc

[0051]

[0052] In Table 1, "1" represents a high level, "0" represents a low level, k is the preset voltage division coefficient, and V temp-sense The induced voltage output by the temperature sensing module is positively correlated with the sensed temperature.

[0053] In other embodiments, besides analog circuits, digital circuits can also be used to achieve the effect that the magnitude of the second low reference voltage V2-L increases with the increase of the temperature of the SiC MOSFET driving circuit. The digital circuit approach can preset the correspondence between the temperature of the SiC MOSFET driving circuit and the hysteresis value of the second enabling module based on the output voltage of the temperature sensing module, and the hysteresis value of the second enabling module decreases as the temperature increases.

[0054] refer to Figure 8In some embodiments, the SiC MOSFET driving circuit further includes a protection logic module and a first AND gate &1. The protection logic module is used to detect abnormal conditions in the SiC MOSFET driving circuit and output the detection result. The first AND gate &1 includes a first input terminal, a second input terminal, and an output terminal. The first input terminal of the first AND gate &1 is used to receive the first enable signal, the second input terminal of the first AND gate &1 is used to receive the detection result of the protection logic module, and the output terminal of the first AND gate &1 is connected to the driving voltage output module. That is, the driving voltage output module can only be started normally when the first enable signal is a start signal and the detection result of the protection logic module is normal.

[0055] The protection logic module may include detection and protection modules such as an over-temperature protection module (OTP) and an over-current protection module (OCP), as well as a second AND gate &2. The over-temperature protection module is used to detect whether the SiC MOSFET driving circuit has an over-temperature condition and outputs a temperature detection result. The over-current protection module is used to detect whether the SiC MOSFET driving circuit has an over-current condition and outputs a current detection result. The second AND gate &2 includes a first input terminal, a second input terminal, and an output terminal. The first input terminal of the second AND gate &2 is connected to the over-temperature protection module (OTP), the second input terminal of the second AND gate &2 is connected to the over-current protection module (OCP), and the output terminal of the second AND gate &2 is connected to the second input terminal of the first AND gate &1.

[0056] refer to Figure 9 The drive voltage output module includes a third AND gate &3 and a buffer circuit. The third AND gate &3 includes a first input terminal, a second input terminal, a third input terminal, and an output terminal. The first input terminal of the third AND gate &3 is used to receive a first enable signal from the first enable module, and the second input terminal of the third AND gate &3 is used to receive a second enable signal from the second enable module. The third input terminal of the third AND gate &3 is connected to the drive signal receiving module. The input terminal of the buffer circuit is connected to the output terminal of the third AND gate &3, and the output terminal of the buffer circuit is connected to the gate of the SiC MOSFET. The function of the buffer circuit is to ensure that the output drive voltage reaches the target value, thereby enhancing the driving capability of the SiC MOSFET. The buffer circuit can adopt a conventional circuit configuration.

[0057] The SiC MOSFET driving circuit adopted in this application embodiment can ensure a higher and more consistent gate drive voltage amplitude for the SiC MOSFET during dynamic response (including power-on, power-off, power-on after a brief power outage, and fluctuations in the supply voltage of the SiC MOSFET driving circuit). This results in smaller amplitude fluctuations in the output drive voltage of the SiC MOSFET driving circuit, leading to a more stable and higher gate voltage value for the SiC MOSFET. Consequently, when the SiC MOSFET driving circuit operates in dynamic response mode, the Rdson (on-resistance) of the SiC MOSFET decreases, thereby correspondingly reducing the conduction loss (Conduction loss = I). 2 *Rdson). Reducing the conduction loss of SiC MOSFETs not only improves system efficiency under dynamic response, but also lowers the temperature on SiC MOSFETs.

[0058] In SiC MOSFET applications, overheating is a bottleneck for system load capacity. This is especially true in SiC MOSFET applications, which typically require higher voltage ratings and larger load currents compared to Si MOSFETs. For example, Si MOSFETs commonly operate at 600V, rarely exceeding 800V. In contrast, SiC MOSFETs are widely used at voltages of 600V, 900V, and 1200V. Furthermore, SiC MOSFETs can handle currents up to 100A, significantly exceeding the current requirements of Si MOSFETs. Therefore, SiC MOSFET applications demand higher precision in temperature detection, requiring faster temperature feedback, higher accuracy, and redundant temperature sensing design within the system. The technical solution presented in this application feeds back temperature detection to the internal control of the SiC MOSFET drive circuit, thereby enabling adaptive adjustment of the turn-on voltage. When the SiC MOSFET drive circuit is already at a high ambient temperature, or the SiC MOSFET has been operating for a period of time and has accumulated a certain amount of power consumption, the temperature of the MOSFET drive circuit will rise. During the dynamic response process, this can help reduce the extent to which the temperature of the MOSFET drive circuit continues to rise, thereby pushing the SiC MOSFET to a higher current level (outputting greater load power) and also reducing the cost of the MOSFET drive circuit heat dissipation design.

[0059] Meanwhile, when two or more SiC MOSFETs are connected in parallel, if the gate voltage of the SiC MOSFET is relatively small, Rdson may even have a negative temperature coefficient. As the temperature rises, Rdson will decrease. Between the two SiC MOSFETs connected in parallel, the device with the higher temperature will share a larger current, which will eventually cause the device sharing the larger current to be damaged by overcurrent.

[0060] In summary, the SiC MOSFET driving circuit of this application enables the start-up and output of the driving voltage output module and the output of the driving voltage through the first enable signal and the second enable signal output by the first enable module and the second enable module, respectively. This solves the problem that existing SiC MOSFET driving circuits cannot take into account both the start-up delay time and the initial driving voltage. At the same time, by dynamically reducing the hysteresis value of the second enable module, the problem that the dynamic working gate voltage of SiC MOSFET may be too low is solved, thereby reducing conduction losses, reducing thermal effects, and improving the safety of SiC MOSFET.

[0061] After reading this application, those skilled in the art will understand that the foregoing content is presented by way of example only and is not restrictive. Although not explicitly stated herein, those skilled in the art will understand that this application is intended to encompass various reasonable changes, improvements, and modifications to the embodiments. Such changes, improvements, and modifications are all within the spirit and scope of the exemplary embodiments of this application.

Claims

1. A SiC MOSFET driving circuit, characterized in that, include: The first enabling module is configured to receive a supply voltage, compare the supply voltage with a first reference voltage, and output a first enabling signal; A second enabling module is configured to receive the supply voltage, compare the supply voltage with a second reference voltage, and output a second enabling signal, wherein the second reference voltage is greater than the first reference voltage. The second enabling module includes: A second reference voltage circuit is used to provide the second reference voltage, and includes a second high reference voltage circuit, a second low reference voltage circuit, and a third inverter. The second high reference voltage circuit is used to output the second high reference voltage and is connected to the second input terminal of the second comparator through a third MOSFET. The second low reference voltage circuit is used to output the second low reference voltage and is connected to the second input terminal of the second comparator through a fourth MOSFET. The input terminal of the third inverter is connected to the output terminal of the second comparator, and the output terminal of the third inverter is connected to the gate of the fourth MOSFET. The magnitude of the second low reference voltage output by the second low reference voltage circuit increases with the increase of the temperature of the SiC MOSFET driving circuit. The second comparator includes a first input terminal, a second input terminal, and an output terminal. The first input terminal of the second comparator is used to receive the supply voltage. The second input terminal of the second comparator is connected to the second reference voltage circuit. The output terminal of the second comparator is used to output the comparison result between the supply voltage and the second reference voltage. The fourth inverter has its input terminal connected to the output terminal of the third inverter, and its output terminal connected to the drive voltage output module. The drive signal receiving module is configured to receive and output the control logic signals of the SiC MOSFET; A drive voltage output module, connected to the first enable module, the second enable module, and the drive signal receiving module, is configured to provide a drive voltage to the gate of the SiC MOSFET based on the first enable signal, the second enable signal, and the control logic signal. The first enable signal enables the drive voltage output module to start or not, and the second enable signal enables the drive voltage output module to output the drive voltage. The drive voltage output module includes: a third AND gate, comprising a first input, a second input, a third input, and an output; the first input of the third AND gate receives the first enable signal from the first enable module, the second input of the third AND gate receives the second enable signal from the second enable module, and the third input of the third AND gate is connected to the drive signal receiving module; and a buffer circuit, the input of which is connected to the output of the third AND gate, and the output of which is connected to the gate of the SiC MOSFET.

2. The SiC MOSFET driving circuit according to claim 1, characterized in that, When the supply voltage increases to a level not less than the second reference voltage, the second enable signal becomes the output drive voltage signal.

3. The SiC MOSFET driving circuit according to claim 1, characterized in that, When the supply voltage is less than the second reference voltage, the second enable signal is to not output the drive voltage signal.

4. The SiC MOSFET driving circuit according to claim 1, characterized in that, When the supply voltage increases to a level not less than the first reference voltage, the first enable signal becomes a start signal.

5. The SiC MOSFET driving circuit according to claim 1, characterized in that, When the supply voltage is less than the first reference voltage, the first enable signal is a non-start signal.

6. The SiC MOSFET driving circuit according to claim 1, characterized in that, The SiC MOSFET driving circuit also includes: an over-temperature protection module; The over-temperature protection module includes a temperature sensing module, which is used to sense the temperature of the SiC MOSFET driving circuit and output a sensing voltage that is positively correlated with the temperature. The second low reference voltage circuit includes a voltage regulation module, which receives the induced voltage, regulates the induced voltage, and outputs it. The voltage output by the voltage regulation module is not higher than the second high reference voltage output by the second high reference voltage circuit, and is not lower than the minimum operating voltage for the SiC MOSFET driving circuit to start.

7. The SiC MOSFET driving circuit according to claim 6, characterized in that, The voltage regulation module includes: A third comparator, the third comparator including a first input terminal, a second input terminal, and an output terminal; The sixth resistor has one end connected to the first input terminal of the third comparator and the other end connected to the temperature sensing module; The seventh resistor has one end connected to the second input terminal of the third comparator and the other end grounded. The eighth resistor has one end connected to the second input terminal of the third comparator and the other end connected to the output terminal of the third comparator. The ninth resistor has one end connected to the first input terminal of the third comparator and the other end connected to the output terminal of the third comparator. The tenth resistor has one end connected to the first input terminal of the third comparator and the other end connected to ground; A voltage clamping circuit, connected to one end of the ninth resistor and the tenth resistor, is used to ensure that the output second low reference voltage is not higher than the second high reference voltage and not lower than the minimum operating voltage required to start the SiC MOSFET drive circuit.

8. The SiC MOSFET driving circuit according to claim 7, characterized in that, The voltage clamping circuit includes: The fourth comparator has its first input terminal connected to one end of the ninth resistor and the tenth resistor, its second input terminal connected to the second high reference voltage circuit, and its output terminal used to output the fourth comparison result. The fifth comparator has its first input terminal connected to the second low reference voltage circuit, its second input terminal connected to one end of the ninth resistor and the tenth resistor, and its output terminal used to output the fifth comparison result. The NOR gate has a first input terminal for receiving the fourth comparison result, a second input terminal for receiving the fifth comparison result, and an output terminal for outputting the sixth result. A first switch, one end of which is connected to one end of the ninth resistor and one end of the tenth resistor, and the other end of which is connected to the connection node between the second low reference voltage circuit and the fourth MOS transistor, and the first switch is controlled by the NOR gate; The second switch has one end connected to the second high reference voltage circuit and the other end connected to the connection node between the second low reference voltage circuit and the fourth MOS transistor, and the second switch is controlled by the fourth comparator. A third switch, one end of which is connected to the second low reference voltage circuit, and the other end of which is connected to the connection node between the second low reference voltage circuit and the fourth MOS transistor, and the third switch is controlled by the fifth comparator.

9. The SiC MOSFET driving circuit according to claim 1, characterized in that, The first enabling module includes: A first reference voltage circuit is used to provide the first reference voltage; The first comparator includes a first input terminal, a second input terminal, and an output terminal. The first input terminal of the first comparator is used to receive the supply voltage. The second input terminal of the first comparator is connected to the first reference voltage circuit. The output terminal of the first comparator is used to output the comparison result between the supply voltage and the first reference voltage.

10. The SiC MOSFET driving circuit according to claim 9, characterized in that, The first reference voltage circuit includes: A first high reference voltage circuit is used to provide a first high reference voltage and is connected to the second input terminal of the first comparator through a first MOSFET. A first low reference voltage circuit is used to provide a first low reference voltage and is connected to the second input terminal of the first comparator through a second MOSFET. The first inverter has its input terminal connected to the output terminal of the first comparator and the gate of the second MOS transistor, and its output terminal connected to the gate of the first MOS transistor. The first enable module further includes a second inverter, the input of which is connected to the output of the first inverter, and the output of which is connected to the drive voltage output module.

11. The SiC MOSFET driving circuit according to claim 1, characterized in that, The SiC MOSFET driving circuit also includes: The protection logic module is used to detect abnormal conditions in the SiC MOSFET driving circuit and output the detection results. The first AND gate includes a first input terminal, a second input terminal, and an output terminal. The first input terminal of the first AND gate is used to receive the first enable signal, the second input terminal of the first AND gate is used to receive the detection result of the protection logic module, and the output terminal of the first AND gate is connected to the drive voltage output module.

12. The SiC MOSFET driving circuit according to claim 11, characterized in that, The protection logic module includes: An over-temperature protection module is used to detect whether the SiC MOSFET driving circuit has an over-temperature condition and output the temperature detection result; An overcurrent protection module is used to detect whether the SiC MOSFET driving circuit has an overcurrent condition and output the current detection result; The second AND gate includes a first input terminal, a second input terminal, and an output terminal. The first input terminal of the second AND gate is connected to the over-temperature protection module, the second input terminal of the second AND gate is connected to the over-current protection module, and the output terminal of the second AND gate is connected to the second input terminal of the first AND gate.

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