SiC MOSFET Drive Control Circuit with Adjustable Drive Voltage and Resistance

Abstract

The present invention relates to a driving voltage and resistance adjustable SiC MOSFET driving control circuit, belonging to the technical field of SiC MOSFET driving, and solves the problem that it is difficult to ensure high gain, simple structure, high stability and high efficiency in the prior art. The converter includes a control chip, a SiC MOSFET device, power supplies V G1 ~V G2 , switching transistors S1 to S6, resistors R G1 ~R G2 ; wherein, the control chip is used to output control signals of the switching transistors S1 to S6 to the gates of the switching transistors S1 to S6; the drains of the switching transistors S1 and S2 are respectively connected to the positive pole of the power supply V G1 ; the drains of the switching transistors S3 to S5 are respectively connected to the negative pole of the power supply V G1 , the negative pole of the power supply V G2 and grounded; the drain of the switching transistor S6 is connected to the positive pole of the power supply V G2 ; and, the sources of the switching transistors S1 and S3 are respectively connected to the gate of the SiC MOSFET device through the resistors R G1 ; the sources of the switching transistors S2 and S4 are respectively connected to the gate of the SiC MOSFET device through the resistors R G2 ; the sources of the switching transistors S5 and S6 are connected to the source of the SiC MOSFET device. This circuit can ensure the safe and reliable operation of the SiC MOSFET device.

Description

Technical Field

[0001] The present invention relates to the technical field of SiC MOSFET drive control, and particularly to a SiC MOSFET drive control circuit with adjustable drive voltage and resistance. Background Art

[0002] With the rapid development of power electronics technology, SiC MOSFET devices have emerged. They have the characteristics of high switching speed, low loss, and high operating frequency, and are widely used in the field of power electronic converter technology.

[0003] Currently, the source-drain output voltage / current change rate of existing SiC MOSFET devices is relatively high. When the switching speed is low, parasitic parameters will have a significant impact on their performance, the crosstalk problem is serious, the turn-off overvoltage and oscillation are serious, and the switching frequency is limited.

[0004] In response to the above problems, there are mainly two improvement methods in the prior art: one is to increase the gate resistance, and the other is to increase the gate voltage. However, for the first method, the greater the gate resistance increased, the slower the switching speed of the SiC MOSFET device and the obvious increase in loss, that is, the highest switching frequency at which the device can operate is sacrificed. For the second method, the higher the positive voltage of V G the faster the gate-source voltage reaches the threshold voltage and the faster the turn-on speed of the SiC MOSFET device, and the lower the negative voltage of V G the faster the turn-off speed of the SiC MOSFET device. However, it will bring problems of oscillation and crosstalk. Summary of the Invention

[0005] In view of the above analysis, the embodiments of the present invention aim to provide a SiC MOSFET drive control circuit with adjustable drive voltage and resistance to solve the problem that it is difficult to simultaneously ensure high gain, simple structure, high stability, and high efficiency in the prior art.

[0006] On the one hand, the embodiments of the present invention provide a SiC MOSFET drive control circuit with adjustable drive voltage and resistance, including a control chip, a SiC MOSFET device, power supplies V G1 ~V G2 , switching transistors S1 to S6, and resistors R G1 ~R G2 ; wherein, the resistance value R G1 < R G2 , and the power supply voltage V G1 > V G2 ;

[0007] The control chip is used to output control signals of the switching transistors S1 to S6 to the gates of the switching transistors S1 to S6;

[0008] The drains of switching transistors S1 and S2 are respectively connected to the positive pole of power supply V G1 ; the drains of switching transistors S3 to S5 are respectively connected to the negative pole of power supply V G1 , the negative pole of power supply V G2 , and are grounded; the drain of switching transistor S6 is connected to the positive pole of power supply V G2 ; and,

[0009] The sources of switching transistors S1 and S3 are respectively connected to the gate of the SiC MOSFET device via resistors R G1 ; the sources of switching transistors S2 and S4 are respectively connected to the gate of the SiC MOSFET device via resistors R G2 ; the sources of switching transistors S5 and S6 are connected to the source of the SiC MOSFET device.

[0010] The beneficial effects of the above technical solution are as follows: By using the switched-capacitor technology in combination with the traditional coupled inductor, a relatively high voltage gain can be achieved, and the structure is simple. By controlling the on-off timing of switching transistors S1 to S6, within one switching period, the SiC MOSFET device can give full play to the advantages of high switching speed and low loss, while avoiding hazards such as oscillation and crosstalk, and enhancing its ability to operate efficiently and reliably. Moreover, the stress of each switching transistor is relatively low, far lower than the output voltage. In order to ensure the high switching speed and low loss of the SiC MOSFET device, while avoiding hazards such as oscillation and crosstalk, the drive voltage (power supplies V G1 to V G2 ) and drive resistors (resistors R G1 to R G2 ) and other parameters should be appropriately adjusted according to requirements during the switching process.

[0011] Based on the further improvement of the above circuit, the SiC MOSFET drive control circuit further includes resistors R g , capacitors C gd , C gs , C ds , and diode D1; wherein,

[0012] Resistors R G1 , R G2 are respectively connected to the gate of the SiC MOSFET device via resistor R g ;

[0013] The gate of the SiC MOSFET device is also connected to its drain via capacitor C gd , and is connected to its source via capacitor C gs ; A parallel-connected capacitor C ds and diode D1 are connected between the source and drain of the SiC MOSFET device.

[0014] The beneficial effects of the above further improvement scheme are: Capacitor C gd , C gs , C ds , and diode D1 are all used to protect the SiCMOSFET device. The above improvement can improve the accuracy of subsequent parameter design and control signal timing.

[0015] Further, the control signals of switch tubes S1 to S6 output by the control chip are all rectangular wave control signals; and,

[0016] Within one switching cycle of the SiC MOSFET device, the waveforms of the control signals of switch tubes S1 to S4 are complementary, so that S1 to S4 are started in sequence; the control signal of switch tube S5 is the superposition of the control signals of S1 and S4, and the control signal of switch tube S6 is the superposition of the control signals of S2 and S3.

[0017] The beneficial effects of the above further improvement scheme are: By turning on and off switch tubes S1 to S6 in an orderly manner, the four working modes of the SiC MOSFET device are orderly and stable.

[0018] Further, the control chip executes the following program:

[0019] According to the gate-source safety voltage (V - , V + ) of the SiC MOSFET device, determine the amplitude range of power supplies V G1 , V G2 , and recommend them to the user for selecting appropriate power supplies V G1 , V G2 ; where, the amplitudes V G1 , V G2 of power supplies V G1 , V G2 satisfy the following relationship

[0020] V + - V 预设 ≤ V G1 ≤ V +

[0021] |V - | - V 预设 ≤ V G2 ≤ |V - |

[0022] In the formula, V 预设 is a preset value selected by the user, and | | is the absolute value operator;

[0023] According to the selected power supplies V G1 , V G2 , combined with the Miller voltage V miller, capacitor C gd , resistor R g , determine resistor R G1 , R G2 resistance value, recommended to the user for selecting a suitable resistor R G1 , R G2 ;

[0024] According to the selected power supply V above G1 , V G2 , resistor R G1 , R G2 , combined with the duty cycle D and operating frequency f of the SiC MOSFET device, determine the on-time and off-time of the control signals of switches S1 to S4 respectively; off-time = 1 / f - on-time;

[0025] According to the obtained control signals of switches S1 to S4, based on the principle that the control signal of switch S5 is the superposition of the control signals of S1 and S4, and the control signal of switch S6 is the superposition of the control signals of S2 and S3, determine the control signals of switches S5 and S6;

[0026] Output the control signals of the above switches S1 to S6.

[0027] The beneficial effect of the above further improvement scheme is that after selecting the SiC MOSFET device, the control chip automatically gives a suitable power supply V G1 , V G2 , resistor R G1 , R G2 resistance value, and the on-time and off-time of the control signals of S1 to S6 respectively, realizing the matching design of four modes.

[0028] Further, the control chip determines the on-time τ1 to τ4 of the control signals of switches S1 to S4 respectively through the following formula

[0029]

[0030]

[0031]

[0032]

[0033] Where

[0034]

[0035]

[0036]

[0037] Where, V th is the threshold turn-on voltage of the SiC MOSFET device, g fs is the transconductance of the SiC MOSFET device, L S is the source parasitic inductance of the SiC MOSFET device, R G1 and R G2 and R g are the resistance values of R G1 and R G2 and R g respectively, C gd and C gs and C ds are the capacitance values of C gd and C gs and C ds respectively, D is the duty cycle of the SiC MOSFET device, and f is the operating frequency of the SiC MOSFET device.

[0038] The beneficial effect of the above further improvement scheme is: to achieve the accurate design of the pulse width (on-state time) of the control signals of the switching transistors S1 to S4, and ensure that the SiC MOSFET realizes four modes.

[0039] Furthermore, the control chip determines the resistance value R G1 of the resistor R G1

[0040]

[0041] where

[0042]

[0043]

[0044] Where, L pa is the parasitic inductance in the circuit, R pa is the parasitic resistance in the circuit, l, w, and h are the length, width, and thickness of the wire on the PCB board where the SiC MOSFET drive control circuit is arranged respectively, ρ is the conductivity of the wire, and V bus is the rated output voltage of the load.

[0045] The beneficial effect of the above further improvement scheme is: to achieve the precise design of the drive resistor R G1 , which is beneficial to improving the switching speed and working efficiency of the drive circuit, and direct application can greatly reduce the design time and design cost.

[0046] Furthermore, the control chip determines the resistance value R G2 of the resistor R G2

[0047]

[0048] Wherein, V miller is the Miller voltage of the SiC MOSFET device, and C gd is the capacitance value of the capacitor C gd , and R g is the resistance value of the resistor R g .

[0049] The beneficial effect of the above further improvement scheme is: to achieve the precise design of the driving resistor R G2 , which is beneficial to improving the switching speed and working efficiency of the driving circuit, and direct application can greatly reduce the design time and design cost.

[0050] Further, the SiC MOSFET drive control circuit further includes a diode D2 and an inductor L; wherein,

[0051] the drain of the SiC MOSFET device is connected to the positive input terminal of the load through the parallel-connected diode D2 and inductor L, and its source is directly connected to the negative input terminal of the load.

[0052] The beneficial effect of the above further improvement scheme is: to construct a power output loop for the SiC MOSFET device, suppress the output voltage or current oscillation spikes of the SiC MOSFET device, and ensure the safe output of the circuit power.

[0053] Further, the control chip also executes the following program:

[0054] According to the output current amplitude I O required by the user, combined with the duty cycle D and the operating frequency f of the SiC MOSFET device, determine the inductance value of the L, and recommend it to the user for selecting a suitable inductor L.

[0055] The beneficial effect of the above further improvement scheme is: to limit the preset rule of the power inductor L, and direct application can greatly reduce the design time and design cost.

[0056] Further, the control chip determines the inductance value of the L through the following formula

[0057]

[0058] Wherein, D is the duty cycle of the SiC MOSFET device, f is the operating frequency of the SiC MOSFET device, I O is the preset output current amplitude, and V bus is the rated output voltage of the load.

[0059] The beneficial effects of the above further improvement scheme are as follows: realizing the precise design of the inductor L, ensuring that the SiC MOSFET drive control circuit has the set power output capability, and directly applying it can greatly reduce the design time and design cost.

[0060] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent specification, and some advantages can be made obvious from the specification, or understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained from the content specifically pointed out in the specification and the drawings. Description of the Drawings

[0061] The drawings are only used for the purpose of showing specific embodiments, and are not considered as a limitation to the present invention. Throughout the drawings, the same reference signs denote the same components.

[0062] Figure 1 Schematic diagram of the SiC MOSFET drive control circuit with adjustable drive voltage and resistance in Embodiment 1 of the present invention;

[0063] Figure 2 Voltage and current waveform diagram during operation in Embodiment 1 of the present invention;

[0064] Figure 3 Main waveform diagram of the SiC MOSFET drive control circuit in Embodiment 2 of the present invention;

[0065] Figure 4 Schematic diagram of the improved structure of the SiC MOSFET drive control circuit in Embodiment 2 of the present invention;

[0066] Figure 5 Schematic diagram of the principle of the improved structure of the SiC MOSFET drive control circuit in Embodiment 2 of the present invention. Detailed Description of the Preferred Embodiments

[0067] The following will specifically describe the preferred embodiments of the present invention with reference to the drawings, where the drawings form a part of this application and are used together with the embodiments of the present invention to explain the principle of the present invention, and are not used to limit the scope of the present invention.

[0068] Embodiment 1

[0069] A specific embodiment of the present invention discloses a SiC MOSFET drive control circuit with adjustable drive voltage and resistance, as Figure 1 shown, including a control chip, a SiC MOSFET device, power supplies V G1 ~V G2 , switching transistors S1 to S6, resistors R G1 ~RG2 The resistance value R G1 < R G2 and the power supply voltage V G1 > V G2 .

[0070] Among them, the control chip is used to output the control signals of the switching tubes S1 to S6 to the gates of the switching tubes S1 to S6; the drains of the switching tubes S1 and S2 are respectively connected to the positive pole of the power supply V G1 ; the drains of the switching tubes S3 to S5 are respectively connected to the negative pole of the power supply V G1 , the negative pole of the power supply V G2 , and are grounded; the drain of the switching tube S6 is connected to the positive pole of the power supply V G2 ; and the sources of the switching tubes S1 and S3 are respectively connected to the gate of the SiC MOSFET device through the resistor R G1 , and the sources of the switching tubes S2 and S4 are respectively connected to the gate of the SiC MOSFET device through the resistor R G2 ; the sources of the switching tubes S5 and S6 are connected to the source of the SiC MOSFET device.

[0071] The drain of the SiC MOSFET device is connected to the positive pole of the external load output terminal, and the source is connected to the positive pole of the load output terminal. The rated voltage of the load is V bus .

[0072] During implementation Figure 2 the main waveforms of the SiC MOSFET drive control circuit are given. In the waveforms, the top four waveforms are respectively the drive signals of the switching tubes S1 to S4, and the waveforms of the four are complementary. The resistors R G1 and R G2 are the drive resistors in the drive circuit. The larger their resistance values, the better the effect of suppressing the voltage and current oscillation of the SiC MOSFET device, but their working efficiency and switching speed will decrease accordingly. And the smaller their resistance values, although their working efficiency and switching speed performance are better, the oscillation of the SiC MOSFET device during the on-off process will be more obvious. Therefore, the drive resistance value should not be too large or too small.

[0073] Compared with the prior art, the SiC MOSFET drive circuit with adjustable drive voltage and drive resistance provided in this embodiment adjusts and varies the drive resistance and drive voltage of the SiC MOSFET device during a preset period within one working cycle of the SiC MOSFET device, so that the SiC MOSFET device has the ability of fast turn-on and turn-off and high-efficiency operation, giving full play to the advantages of high frequency and high efficiency of the SiC MOSFET device. At the same time, it can effectively suppress the voltage and current oscillations of the SiC MOSFET device during the turn-on and turn-off processes, reduce the transient spikes of the two, and ensure the safe and reliable operation of the SiC MOSFET device.

[0074] Embodiment 2

[0075] Optimized on the basis of Embodiment 1, the SiC MOSFET drive control circuit further includes resistor R g , capacitor C gd , C gs , C ds , diode D1, as shown in Figure 3 .

[0076] Among them, resistor R G1 , R G2 are respectively connected to the gate of the SiC MOSFET device through resistor R g ; the gate of the SiC MOSFET device is also connected to its drain through capacitor C gd , and is connected to its source through capacitor C gs ; a parallel-connected capacitor C ds , diode D1 is connected between the source and drain of the SiC MOSFET device.

[0077] Preferably, the SiC MOSFET drive control circuit further includes diode D2 and inductor L. As shown in Figure 4 . Among them, the drain of the SiC MOSFET device is connected to the positive input terminal of the load through a parallel-connected diode D2 and inductor L, and its source is connected to the negative input terminal of the load.

[0078] Preferably, the switching tube S1-S6 control signals output by the control chip are all rectangular wave control signals; and within one switching cycle of the SiC MOSFET device, the waveforms of the switching tube S1-S4 control signals are complementary, so that S1-S4 are started in sequence; the switching tube S5 control signal is the superposition of the S1 and S4 control signals, and the switching tube S6 control signal is the superposition of the S2 and S3 control signals.

[0079] Preferably, the control chip executes the following program:

[0080] S1. According to the gate-source safe voltage (V- , V + ), determine the power supply V G1 , V G2 amplitude range, recommend it to the user for selecting a suitable power supply V G1 , V G2 .

[0081] V + -V 预设 ≤ V G1 ≤ V +

[0082] V - -V 预设 ≤ V G2 ≤ V - (1)

[0083] Considering that the negative safety voltage V - of the gate-source of the SiC MOSFET is about -10V, and the positive safety voltage V + is generally 20 - 25V, and the recommended working drive voltage is -5 - 20V. Therefore, in the design of this drive circuit, V G1 = 24V, V G2 = 5V. This can ensure the requirements of the SiC MOSFET for the drive voltage and can ensure that the SiC MOSFET has a small on-state resistance value when it is fully turned on, thereby improving the working efficiency of the SiC MOSFET.

[0084] S2. According to the selected power supplies V G1 , V G2 , combined with the Miller voltage V miller (obtained by referring to the user manual of the SiC MOSFET device), capacitance C gd , resistance R g , determine the resistance values of resistors R G1 , R G2 , recommend them to the user for selecting suitable resistors R G1 , R G2 .

[0085] S3. According to the above-selected power supplies V G1 , V G2 , resistors R G1 , R G2 , combined with the duty cycle D and working frequency f of the SiC MOSFET device, determine the on-time and off-time of the control signals of switches S1 - S4 respectively; off-time = 1 / f - on-time.

[0086] S4. According to the obtained control signals of switching transistors S1 to S4, determine the control signals of switching transistors S5 and S6 based on the principle that the control signal of switching transistor S5 is the superposition of the control signals of S1 and S4, and the control signal of switching transistor S6 is the superposition of the control signals of S2 and S3.

[0087] S5. Output the control signals of the above-mentioned switching transistors S1 to S6.

[0088] Preferably, in step S2, the control chip determines the resistance R through the following formula G1 of the resistance value R G1

[0089]

[0090] where

[0091]

[0092]

[0093] In the formula, L pa is the parasitic inductance in the circuit, R pa is the parasitic resistance in the circuit. As Figure 5 shown, l, w, and h are the length, width, and thickness of the wire on the PCB board where the SiC MOSFET drive control circuit is arranged, ρ is the conductivity of the wire, and V bus is the rated output voltage of the load.

[0094] Preferably, the control chip determines the resistance R through the following formula G2 of the resistance value R G2

[0095]

[0096] In the formula, V miller is the Miller voltage of the SiC MOSFET device, C gd is the capacitance value of the capacitor C gd and R g is the resistance value of the resistance R g resistance value.

[0097] Preferably, the control chip determines the on-state time τ1 to τ4 of the control signals of the switching transistors S1 to S4 through the following formula

[0098]

[0099]

[0100]

[0101]

[0102] Among them

[0103]

[0104]

[0105]

[0106] In the formula, V th is the threshold turn-on voltage of the SiC MOSFET device, g fs is the transconductance of the SiC MOSFET device, L S is the source parasitic inductance of the SiC MOSFET device, R G1 , R G2 , R g are the resistance values of R G1 , R G2 , R g respectively, C gd , C gs , C ds are the capacitance values of C gd , C gs , C ds respectively, D is the duty cycle of the SiC MOSFET device, and f is the operating frequency of the SiC MOSFET device.

[0107] Preferably, the control chip also executes the following program:

[0108] S5. According to the output current amplitude I O required by the user, combined with the duty cycle D and operating frequency f of the SiC MOSFET device, determine the inductance value of the L through the following formula, and recommend it to the user for selecting a suitable inductor L

[0109]

[0110] In the formula, D is the duty cycle of the SiC MOSFET device, f is the operating frequency of the SiC MOSFET device, I O is the preset output current amplitude, and V bus is the rated output voltage of the load and also the DC bus voltage of the SiC MOSFET drive control circuit.

[0111] This SiC MOSFET drive control circuit has a total of 4 operating modes in one switching cycle, and the characteristics of each mode are shown in Table 1.

[0112] Table 1

[0113]

[0114]

[0115] The time period from t0 to t1 is Mode 1. In this mode, the switching transistors S1 and S5 are turned on, and the other switching transistors are turned off. The driving voltage of the SiC MOSFET device changes from zero to V G1 , and the driving resistance is R G1 +R g . At the moment of t1, the drain current i D rises to the load current I L , and the freewheeling diode D2 is turned off, and this mode ends. The turn-on delay time of the SiC MOSFET and the rising time of the drain current i D in this mode are relatively short, and the turn-on loss generated is small. Design R G1 <R G2 , V G1 >V G2 , then in this mode, the initial turn-on speed of the SiC MOSFET is extremely fast, and its high-frequency characteristics are reflected.

[0116] The time period from t1 to t2 is Mode 2. In this mode, the switching transistors S2 and S6 are turned on, and the other switching transistors are turned off. The driving voltage of the SiC MOSFET device decreases from V G1 to V G1 -V G2 , and the gate driving resistance increases from R G1 +R g to R G2 +R g . At the moment of t2, the turn-off signal of the SiC MOSFET arrives, and this mode ends. In this mode, the lower driving power supply voltage and the higher gate driving resistance reduce the change speed of the drain-source voltage of the SiC MOSFET, and then the change speed of the voltage of the freewheeling diode D decreases accordingly, and its turn-off overvoltage and oscillation are suppressed.

[0117] The time period from t2 to t3 is Mode 3. In this mode, the auxiliary switching transistors S3 and S6 are turned on, and the other switching transistors are turned off. The driving voltage of the SiC MOSFET device decreases from V G1 -V G2 to -V G2 , and the gate driving resistance decreases from R G2 +R g to R G1 +R g . At the moment of t3, the drain-source voltage of the SiC MOSFET rises to the input voltage V bus, the freewheeling diode D conducts, and this mode ends. In this mode, the turn-off delay time of the SiCMOSFET and the rise time of the drain-source voltage are short, resulting in a small turn-off loss. At the same time, from the perspective of the turn-off speed, the use of negative voltage turn-off and a low turn-off drive resistance both contribute to the rapid turn-off of the device.

[0118] The time period from t3 to t4 is Mode 4. In this mode, the auxiliary switching transistors S4 and S5 conduct, and the other switching transistors are off. The drive voltage of the SiCMOSFET device increases from -V G2 to 0, and the gate drive resistance increases from R G1 +R g to R G2 +R g . At time t4, the turn-on signal of the SiCMOSFET arrives, and this mode ends. In this mode, compared with the turn-off method of negative voltage and low turn-off drive resistance in Mode 3, the turn-off method of zero voltage and high turn-off drive resistance in Mode 4 can reduce the change speed of the drain current of the SiC MOSFET, and thus its turn-off overvoltage and oscillation can be effectively suppressed.

[0119] In summary, by adjusting the drive voltage and drive resistance of the SiC MOSFET in four operating modes, it can ensure that the SiC MOSFET has extremely high turn-on and turn-off speeds, extremely low turn-off overvoltage and oscillation, and low power loss in various modes. Furthermore, the SiC MOSFET can take into account the advantages of high frequency, high efficiency, and high reliability, and improve the operating performance of the SiC MOSFET.

[0120] The derivation process of the above-mentioned formulas is as follows:

[0121] During the time period from t0 to t1, the SiC MOSFET is in the turn-on process. According to Kirchhoff's voltage and current laws, the equations for this process are written as follows

[0122]

[0123] Based on this, the drive voltage V GS can be calculated as follows

[0124]

[0125] where

[0126] s = j2πf

[0127] In the formula, s is the Laplace operator, f is the operating frequency of the SiC MOSFET device, and

[0128]

[0129] In Equations (7) and (8), after the user selects a suitable SiC MOSFET model as needed, the parameter values of the parasitic inductance L pa and the parasitic resistance R pa in the circuit can be estimated according to the actual layout of the PCB. The estimation formula is given by (9), where l, w, and h are the length, width, and thickness of the PCB trace, respectively, and ρ is the conductivity of the PCB trace.

[0130]

[0131] It can be judged that the only unknown in Equation (7) is R G1 . Substituting V GS = V th into the equation, the value of the driving resistance R G1 can be calculated. Here, V th is the threshold turn-on voltage of the SiC MOSFET, which can be obtained by referring to the data sheet. The value of the driving resistance R G1 is

[0132]

[0133] Furthermore, ignoring the parasitic parameters in the circuit, V GS can be obtained as follows

[0134]

[0135] According to the rate of change of the drain-source voltage dV DS / dt set by the user, and substituting V GS = V th , τ1 can be obtained as follows

[0136]

[0137] Since τ1 + τ2 is the conduction time of the SiC MOSFET, and its value is D / f, where D and f are the duty cycle and operating frequency of the SiC MOSFET, respectively, the result of τ2 is as follows

[0138]

[0139] During the time period from t2 to t3, the SiC MOSFET is in the turn-off process. During this process, the capacitor C gd generates a current effect due to the action of the rate of change of the drain-source voltage dV DS / dt, and the magnitude of the current is

[0140]

[0141] where V milleris the Miller voltage of the SiC MOSFET, and this value can be obtained by referring to the data sheet. Substitute the dV DS / dt set by the user, and the value of R G2

[0142]

[0143] In addition, examine the current change rate di DS / dt of the SiC MOSFET at this stage, and its value is

[0144]

[0145] where τ a and τ b are as follows

[0146]

[0147] In Equations (15) and (16), after the user selects a suitable model of the SiC MOSFET as needed, according to the current change rate di DS / dt set by the user, τ3

[0148]

[0149] Since τ3 + τ4 is the turn-off time of the SiC MOSFET, and its value is (1 - D) / f, where D and f are the duty cycle and operating frequency of the SiC MOSFET respectively, the result of τ4 is as follows

[0150]

[0151] The value of the inductor L depends on the magnitude of the output current I O set by the user, and the expression is

[0152]

[0153] Those skilled in the art can understand that all or part of the processes of implementing the above-described embodiment methods can be completed by instructing relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. Among them, the computer-readable storage medium is a magnetic disk, an optical disk, a read-only memory, or a random access memory, etc.

[0154] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A driving voltage and resistance adjustable SiC MOSFET driving control circuit, characterized in that, including a control chip, a SiC MOSFET device, power supplies V G1 ~V G2 , switching transistors S1 to S6, resistors R G1 ~R G2 ; Among them, the resistance value R G1 <R G2 , the power supply voltage V G1 >V G2 ; A control chip for outputting control signals of switching tubes S1 to S6 to the gates of switching tubes S1 to S6; The drains of the switching transistors S1 and S2 are respectively connected to the positive pole of the power supply V G1 ; the drains of the switching transistors S3 to S5 are respectively connected to the negative pole of the power supply V G1 , the negative pole of the power supply V G2 , and are grounded; the drain of the switching transistor S6 is connected to the positive pole of the power supply V G2 ; and The sources of switching transistors S1 and S3 are respectively connected to the gates of the SiC MOSFET devices via resistors R G1 The sources of switching transistors S2 and S4 are respectively connected to the gates of the SiC MOSFET devices via resistors R G2 The sources of switching transistors S5 and S6 are connected to the source of the SiC MOSFET device.

2. The SiC MOSFET drive control circuit with adjustable drive voltage and resistance according to claim 1, characterized in that, It also includes resistor R g , capacitor C gd , C gs , C ds , diode D1; among which, Resistor R G1 , R G2 are respectively connected to the gate of the SiC MOSFET device via resistor R g ; The gate of the SiC MOSFET device is also connected to its drain through capacitor C gd and is connected to its source through capacitor C gs ; A parallel capacitor C ds and diode D1 are connected between the source and drain of the SiC MOSFET device.

3. The SiC MOSFET drive control circuit with adjustable drive voltage and resistance according to claim 2, characterized in that, The control signals of switching tubes S1 to S6 output by the control chip are all rectangular wave control signals; and, Within one switching cycle of the SiC MOSFET device, the waveforms of the control signals of switching tubes S1 to S4 are complementary, so that S1 to S4 are sequentially turned on; the control signal of switching tube S5 is the superposition of the control signals of S1 and S4, and the control signal of switching tube S6 is the superposition of the control signals of S2 and S3.

4. The SiC MOSFET drive control circuit with adjustable drive voltage and resistance according to claim 3, characterized in that, The control chip executes the following program: According to the gate-source safety voltage (V - , V + ) of the SiC MOSFET device, determine the amplitude ranges of power supplies V G1 , V G2 , and recommend them to the user for selecting appropriate power supplies V G1 , V G2 ; among them, the amplitudes V G1 , V G2 of power supplies V G1 , V G2 satisfy the following relationship V + -V 预设 ≤V G1 ≤V + |V - |-V 预设 ≤V G2 ≤|V - | where V 预设 is a preset value selected by the user; According to the selected power supplies V G1 , V G2 , combined with the Miller voltage V miller of the SiC MOSFET device, capacitance C gd , and resistance R g , determine the resistances of resistors R G1 , R G2 , and recommend them to the user for selecting appropriate resistors R G1 , R G2 ; According to the selected power supply V above G1 , V G2 , resistor R G1 , R G2 , combined with the duty cycle D and operating frequency f of the SiC MOSFET device, determine the on-time and off-time of the control signals of switches S1 to S4 respectively; off-time = 1 / f - on-time; According to the obtained control signals of switching tubes S1 to S4, based on the principle that the control signal of switching tube S5 is the superposition of the control signals of S1 and S4, and the control signal of switching tube S6 is the superposition of the control signals of S2 and S3, determine the control signals of switching tubes S5 and S6; Output the above control signals of switching tubes S1 to S6.

5. The SiC MOSFET drive control circuit with adjustable drive voltage and resistance according to claim 4, wherein The control chip determines the on-time τ1 to τ4 of the control signals of switching tubes S1 to S4 respectively through the following formula where Where, V th is the threshold turn-on voltage of the SiC MOSFET device, g fs is the transconductance of the SiC MOSFET device, L S is the source parasitic inductance of the SiC MOSFET device, R G1 , R G2 , R g are the resistance values of R G1 , R G2 , R g respectively, C gd , C gs , C ds are the capacitance values of C gd , C gs , C ds respectively, D is the duty cycle of the SiC MOSFET device, and f is the operating frequency of the SiC MOSFET device.

6. The SiC MOSFET drive control circuit with adjustable drive voltage and resistance according to claim 5, wherein The control chip determines the resistance R of G1 by the following formula G1 where Wherein, L pa is the parasitic inductance in the circuit, R pa is the parasitic resistance in the circuit, l, w, and h are respectively the length, width, and thickness of the wire on the PCB board where the SiC MOSFET drive control circuit is arranged, ρ is the conductivity of the wire, and V bus is the rated output voltage of the load.

7. The SiC MOSFET drive control circuit with adjustable drive voltage and resistance according to claim 6, characterized in that, The control chip determines the resistance R of G2 resistor R by the following formula G2 Where, V miller is the Miller voltage of the SiC MOSFET device, C gd is the capacitance value of the capacitor Cgd, R g is the resistance value of the resistor R g resistance value.

8. The SiC MOSFET drive control circuit with adjustable drive voltage and resistance according to any one of claims 1-2, 4-7, characterized in that It also includes a diode D2 and an inductor L; among them, The drain of the SiC MOSFET device is connected to the positive input terminal of the load through the parallel-connected diode D2 and inductor L, and its source is directly connected to the negative input terminal of the load.

9. The driving voltage and resistance adjustable SiC MOSFET driving control circuit according to claim 8, characterized in that, The control chip also executes the following program: Output current amplitude I according to user requirements O , in combination with the duty cycle D and operating frequency f of the SiC MOSFET device, determine the inductance value of the inductor L, and recommend it to the user for selecting a suitable inductor L.

10. The SiC MOSFET drive control circuit with adjustable drive voltage and resistance according to claim 9, characterized in that, The control chip determines the inductance value of the L through the following formula where D is the duty cycle of the SiC MOSFET device, f is the operating frequency of the SiC MOSFET device, I O is the preset output current amplitude, and V bus is the rated output voltage of the load.

Images