Circuit for adjusting turn-on rate of power device based on Miller platform

Abstract

The invention relates to a circuit for adjusting the turn-on rate of a power device based on a Miller platform, and relates to the technical field of power device driving. The circuit comprises a first driving unit, a current adjusting unit, a field effect transistor Q1, a sampling unit, a sampling conditioning unit and a second driving unit. The output end of the first driving unit is electrically connected to the control end of the field effect transistor Q1 and the input end of the current adjusting unit, the first input end of the sampling unit is electrically connected to the input end of the field effect transistor Q1 and the output end of the field effect transistor Q1, and the output end of the field effect transistor Q1 and the output end of the sampling unit are both electrically connected to the input end of the sampling conditioning unit. The output end of the sampling conditioning unit is electrically connected to the control end of the current adjusting unit through the second driving unit. The field effect transistor has the effect of effectively improving the efficiency of adjusting the opening speed of the field effect transistor.

Description

Technical Field

[0001] This application relates to the technical field of power device driving, and in particular, to a circuit for adjusting the turn-on rate of a power device based on the Miller plateau. Background Art

[0002] Power switching transistors such as IGBTs and MOSFETs are widely used in power electronic devices, covering multiple fields such as industrial control, consumer electronics, and new energy. With the development of technology, the performance optimization of these devices directly affects the overall circuit efficiency and stability, especially in high-frequency switching applications. Efficient power switch management can not only significantly reduce energy losses but also greatly improve the dynamic response characteristics and reliability of the system.

[0003] In response to the need to adjust the turn-on rate of power switching transistors, currently, there are mainly two methods in the industry: one is to adjust the current intensity by fixing driving resistors with different resistances; the other is to introduce variable resistors or potentiometers and other components into the driving circuit to achieve preliminary automated control.

[0004] However, the common problems in the existing technology are insufficient adjustment accuracy and cumbersome and time-consuming operation. For example, the traditional physical replacement resistor method requires frequent disassembly and assembly of hardware components, which not only increases the maintenance cost but also easily leads to the risk of human error. Summary of the Invention

[0005] In order to effectively improve the efficiency of adjusting the turn-on speed of a field-effect transistor, this application provides a circuit for adjusting the turn-on rate of a power device based on the Miller plateau.

[0006] The circuit for adjusting the turn-on rate of a power device based on the Miller plateau provided by this application adopts the following technical solution: A circuit for adjusting the turn-on rate of a power device based on the Miller plateau includes a first driving unit, a current regulating unit, a field-effect transistor Q1, a sampling unit, a sampling conditioning unit, and a second driving unit; the output end of the first driving unit is electrically connected to the control end of the field-effect transistor Q1 and the input end of the current regulating unit, the first input end of the sampling unit is electrically connected to the input end and the output end of the field-effect transistor Q1, and the output end of the field-effect transistor Q1 and the output end of the sampling unit are both electrically connected to the input end of the sampling conditioning unit, and the output end of the sampling conditioning unit is electrically connected to the control end of the current regulating unit through the second driving unit; The current regulation unit includes an adjustable power supply Vx, a PMOS transistor Q2, a resistor Rx, a diode D3, and a current mirror module. The gate of the PMOS transistor Q2 is electrically connected to the output terminal of the second driving unit. The drain of the PMOS transistor Q2 is electrically connected to the output terminal of the field effect transistor Q1. The source of the PMOS transistor Q2 is electrically connected to the negative electrode of the power supply Vx. The positive electrode of the power supply Vx is electrically connected to one end of the resistor Rx. The other end of the resistor Rx is electrically connected to the first input terminal and the control terminal of the current mirror module. The second input terminal of the current mirror module is electrically connected to the control terminal of the field effect transistor Q1. The output terminal of the current mirror module is electrically connected to the drain of the PMOS transistor Q2.

[0007] By adopting the above technical solution, the sampling unit and the sampling conditioning unit can monitor the working state of the field effect transistor Q1 in real time, and control the on and off of the current regulation unit through the second driving unit. The current value flowing into the current regulation unit is inversely proportional to the current value flowing into the control terminal of the field effect transistor Q1. When the field effect transistor Q1 enters the Miller plateau, at this time, by controlling the output voltage value of the power supply Vx, the current value flowing through the resistor Rx can be controlled, and then the current value flowing into the current regulation unit can be controlled through the current mirror module to realize the regulation of the current flowing into the gate of the field effect transistor Q1. When the gate current is large, the switching-on speed of the field effect transistor Q1 is fast; when the gate current is small, the switching-on speed of the field effect transistor Q1 slows down, so that the effect of improving the efficiency of regulating the switching-on speed can be achieved.

[0008] Preferably, the current mirror module includes a triode T1 and a triode T2. The end of the resistor Rx far from the power supply Vx is electrically connected to the gate and the collector of the triode T1. The base of the triode T1 is electrically connected to the base of the triode T2. The emitter of the triode T1 is electrically connected to the emitter of the triode T2 and is electrically connected to the drain of the PMOS transistor Q2.

[0009] By adopting the above technical solution, the current mirror function is realized by the triode T1 and the triode T2 to accurately copy and regulate the current.

[0010] Preferably, the current regulation unit further includes a diode D3. The positive electrode of the diode D3 is electrically connected to the control terminal of the field effect transistor Q1. The negative electrode of the diode D3 is electrically connected to the collector of the triode T2.

[0011] By adopting the above technical solution, the diode D3 is used to ensure the unidirectional operation of the current mirror module and improve the reliability of the circuit.

[0012] Preferably, the sampling unit includes a resistor R1 and a capacitor C1. One end of the resistor R1 is electrically connected to the output end of the field effect transistor Q1, and the other end of the resistor R1 is electrically connected to the input end of the field effect transistor Q1 through the capacitor C1. Both ends of the resistor R1 are respectively electrically connected to the first input end and the second input end of the sampling conditioning unit.

[0013] By adopting the above technical solution, the switching state of the field effect transistor Q1 is detected through the resistor R1 and the capacitor C1, and an accurate sampling signal is provided.

[0014] Preferably, it further includes a diode D1. The output end of the first driving unit is electrically connected to the positive electrode of the diode D1, and the negative electrode of the diode D1 is electrically connected to the control end of the field effect transistor Q1.

[0015] By adopting the above technical solution, the diode D1 can prevent the reverse current from damaging the output end of the first driving unit and protect the integrity of the driving signal.

[0016] Preferably, it further includes a turn-on resistor Ron. The negative electrode of the diode D1 is electrically connected to one end of the turn-on resistor Ron, and the other end of the turn-on resistor Ron is electrically connected to the control end of the field effect transistor Q1.

[0017] By adopting the above technical solution, the turn-on resistor Ron limits the charging current to the gate of the field effect transistor Q1.

[0018] Preferably, it further includes a diode D2. The positive electrode of the diode D2 is electrically connected to the control end of the field effect transistor Q1, and the negative electrode of the diode D2 is electrically connected to the output end of the first driving unit.

[0019] By adopting the above technical solution, the addition of the diode D2 can prevent the reverse current from damaging the control end of the field effect transistor Q1, especially at the moment of turn-off.

[0020] Preferably, it further includes a turn-off resistor Roff. The positive electrode of the diode D2 is electrically connected to one end of the turn-off resistor Roff, and the other end of the turn-off resistor Roff is electrically connected to the control end of the field effect transistor Q1.

[0021] By adopting the above technical solution, the turn-off resistor Roff can limit the falling rate of the turn-off current and avoid voltage spikes and current surges caused by too fast turn-off speed.

[0022] In summary, the present application includes at least one of the following beneficial technical effects: 1. The current value mirror module and the adjustable power supply Vx in the current regulation unit can accurately control the magnitude and change rate of the turn-on current, avoiding the operation of manually replacing the driving resistor in the traditional method, and significantly improving the efficiency of regulating the turn-on rate of the power switch tube. By precisely regulating the power supply voltage Vx to control the magnitude of the current flowing through the current mirror circuit, the fine adjustment of the current flowing into the gate of the field effect transistor Q1 is realized, and the problem of insufficient regulation accuracy is solved to the greatest extent. 2. Through the feedback mechanism of the current regulation unit and the sampling conditioning unit, the turn-on speed can be automatically adjusted according to the actual working conditions. Description of the Drawings

[0023] Figure 1 It is the circuit diagram of the embodiment of the present application.

[0024] Reference signs: 1. Current regulation unit; 11. Current mirror module; 2. Sampling unit. Detailed Embodiment

[0025] The following further Figure 1 describes the present application in detail.

[0026] The embodiment of the present application discloses a circuit for regulating the turn-on rate of a power device based on the Miller platform.

[0027] Referring to Figure 1 , a circuit for regulating the turn-on rate of a power device based on the Miller platform includes a first driving unit, a current regulation unit 1, a field effect transistor Q1, a sampling unit 2, a sampling conditioning unit, and a second driving unit. The output end of the first driving unit is electrically connected to the control end of the field effect transistor Q1 and the input end of the current regulation unit 1; the first input end of the sampling unit 2 is electrically connected to the input end and the output end of the field effect transistor Q1, and the output end of the field effect transistor Q1 and the output end of the sampling unit 2 are both electrically connected to the input end of the sampling conditioning unit. The output end of the sampling conditioning unit is electrically connected to the control end of the current regulation unit 1 through the second driving unit. By the sampling conditioning unit, the voltage between the input end and the output end of the field effect transistor Q1 is sampled and output to the second driving unit. After receiving the trigger signal from the sampling conditioning unit, the second driving unit starts the current regulation unit 1, and then can control the magnitude of the current output to the control end of the field effect transistor Q1, realizing the regulation of the conversion speed of the field effect transistor Q1.

[0028] The field effect transistor Q1 can be set as an NMOS transistor or a PMOS transistor. In this embodiment, it is taken as an example of an NMOS transistor for illustration. This embodiment also includes a diode D1, a turn-on resistor Ron, a diode D2, and a turn-off resistor Roff. The output terminal of the first driving unit is electrically connected to the positive electrode of the diode D1, the negative electrode of the diode D1 is electrically connected to one end of the turn-on resistor Ron, and the other end of the turn-on resistor Ron is electrically connected to the gate of the field effect transistor Q1 and the input terminal of the current regulating unit 1. The output terminal of the first driving unit is also electrically connected to the negative electrode of the diode D2, the diode D2 is electrically connected to one end of the turn-off resistor Roff, and the other end of the turn-off resistor Roff is electrically connected to the gate of the field effect transistor Q1.

[0029] By setting the diode D1, it can ensure that the output signal of the first driving unit flows unidirectionally to the gate of the field effect transistor Q1, and the turn-on resistor Ron plays a current limiting role. After the field effect transistor Q1 is turned off, the charge on the gate of the field effect transistor Q1 can be discharged through the turn-off resistor Roff, and by setting the diode D2, it can ensure the unidirectional discharge of the charge on the gate of the field effect transistor Q1.

[0030] When the first driving circuit outputs a high level, the current value flowing through the turn-on resistor Ron at this time is equal to the current value input to the current regulating unit 1 plus the current value for charging the gate of the field effect transistor Q1. When the current regulating unit 1 controls the increase of the current value flowing through itself, the current value for charging the gate of the field effect transistor Q1 decreases at this time; conversely, when the current regulating unit 1 controls the decrease of the current value flowing through itself, the current value for charging the gate of the field effect transistor Q1 increases at this time.

[0031] The current regulating unit 1 includes an adjustable power supply Vx, a PMOS transistor Q2, a resistor Rx, a diode D3, and a current mirror module 11, and the current mirror module 11 includes a triode T1 and a triode T2. The gate of the PMOS transistor Q2 is electrically connected to the output terminal of the second driving unit, the drain of the PMOS transistor Q2 is electrically connected to the source of the field effect transistor Q1, the source of the PMOS transistor Q2 is electrically connected to the negative electrode of the power supply Vx, the positive electrode of the power supply Vx is electrically connected to one end of the resistor Rx, the other end of the resistor Rx is electrically connected to the base and collector of the triode T1, the base of the triode T1 is electrically connected to the base of the triode T2, and the emitter of the triode T1 is electrically connected to the emitter of the triode T2 and is electrically connected to the drain of the PMOS transistor Q2. The collector of the triode T2 is electrically connected to the negative electrode of the diode D3, and the positive electrode of the diode D3 is electrically connected to the gate of the field effect transistor Q1.

[0032] The triode T1 and the triode T2 are combined into a current mirror module 11. When the second driving module outputs a low level to the gate of the PMOS transistor Q2, the PMOS transistor Q2 is turned on at this time. When the current mirror module 11 works normally, the current value flowing through the diode D3 is approximately equal to the current value flowing through the resistor Rx. By adjusting the output voltage of the power supply Vx, the current value flowing through the resistor Rx can be adjusted, so that the current value flowing through the diode D3 can be realized.

[0033] When a current is input to the gate of the field effect transistor Q1, the gate-source capacitor Cgs is first charged, so that the voltage value between the gate and the source rises until it reaches the threshold voltage of the field effect transistor Q1, and then the field effect transistor Q1 starts to conduct. After conducting and entering the Miller plateau, the voltage value between the drain and the source starts to drop. At this time, the gate current mainly charges the gate-drain capacitor Cgd, and the voltage value between the gate and the source remains unchanged, forming the Miller plateau. When the gate current is large, the charging speed of the gate-drain capacitor Cgd is fast at this time, and the voltage value between the drain and the source drops rapidly, and the switching speed of the field effect transistor Q1 is fast; when the gate current is small, the charging speed of the gate-drain capacitor Cgd is slow at this time, and the voltage value between the drain and the source drops slowly, and the switching speed of the field effect transistor Q1 slows down.

[0034] The sampling unit 2 includes a capacitor R1 and a capacitor C1. One end of the resistor R1 is electrically connected to the source of the field effect transistor Q1, and the other end of the resistor R1 is electrically connected to the drain of the field effect transistor Q1 through the capacitor C1. Both ends of the resistor R1 are respectively electrically connected to the first input end and the second input end of the sampling conditioning unit. When the field effect transistor conducts, the discharge current of the capacitor C1 can generate a voltage drop on the resistor R1, and the generated voltage drop can be input to the sampling conditioning unit. The sampling conditioning unit outputs a reversed driving signal after comparing the voltage drop with a certain reference voltage. After receiving the driving signal, the second driving unit outputs a low level signal to turn on the switching transistor Q2, and then the magnitude of the gate current value can be controlled by controlling the output voltage value of the power supply VS.

[0035] The implementation principle of a circuit for adjusting the turn-on rate of a power device based on the Miller platform in an embodiment of this application is as follows: The sampling unit 2 and the sampling conditioning unit can monitor the working state of the field-effect transistor Q1 in real time, and control the turn-on and turn-off of the current adjustment unit 1 through the second driving unit. The current value flowing into the current adjustment unit 1 is inversely proportional to the current value flowing into the control terminal of the field-effect transistor Q1. When the current value flowing into the current adjustment unit 1 increases, the current value flowing into the control terminal of the field-effect transistor Q1 decreases. When the field-effect transistor Q1 enters the Miller platform stage, by adjusting the output voltage of the power supply Vx, the current value flowing through the resistor Rx can be controlled, and then the current value flowing through the diode D3 can be adjusted by using the current mirror module 11, and finally the precise control of the gate current of the field-effect transistor Q1 is realized. When the gate current is large, the turn-on speed of the field-effect transistor Q1 is accelerated; when the gate current is small, the turn-on speed is slowed down. This design can effectively improve the adjustment efficiency of the turn-on speed and avoid the operation of manually replacing the driving resistor in the traditional way.

[0036] The above are all preferred embodiments of this application, and the protection scope of this application is not limited accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A circuit for adjusting the turn-on rate of a power device based on a Miller platform, characterized in that: The invention comprises a first driving unit, a current regulating unit (1), a field effect transistor Q1, a sampling unit (2), a sampling conditioning unit and a second driving unit; the output end of the first driving unit is electrically connected to the control end of the field effect transistor Q1 and the input end of the current regulating unit (1); the first input end of the sampling unit (2) is electrically connected to the input end of the field effect transistor Q1 and the output end of the field effect transistor Q1; the output end of the field effect transistor Q1 and the output end of the sampling unit (2) are both electrically connected to the input end of the sampling conditioning unit; the output end of the sampling conditioning unit is electrically connected to the control end of the current regulating unit (1) through the second driving unit; The current regulating unit (1) comprises an adjustable power supply Vx, a PMOS tube Q2, a resistor Rx, a diode D3 and a current mirror module (11), wherein the gate of the PMOS tube Q2 is electrically connected to the output end of the second driving unit, the drain of the PMOS tube Q2 is electrically connected to the output end of the field effect tube Q1, the source of the PMOS tube Q2 is electrically connected to the negative electrode of the power supply Vx, the positive electrode of the power supply Vx is electrically connected to one end of the resistor Rx, the other end of the resistor Rx is electrically connected to a first input end and a control end of the current mirror module (11), the second input end of the current mirror module (11) is electrically connected to the control end of the field effect tube Q1, and the output end of the current mirror module (11) is electrically connected to the drain of the PMOS tube Q2.

2. A circuit for adjusting the turn-on rate of a power device based on a Miller platform according to claim 1, characterized in that: The current mirror module (11) comprises a transistor T1 and a transistor T2, one end of the resistor Rx away from the power supply Vx is electrically connected to the gate and collector of the transistor T1, the base of the transistor T1 is electrically connected to the base of the transistor T2, and the emitter of the transistor T1 is electrically connected to the emitter of the transistor T2 and is electrically connected to the drain of the PMOS tube Q2.

3. A circuit for adjusting the turn-on rate of a power device based on a Miller platform according to claim 2, characterized in that: The current regulating unit (1) further comprises a diode D3, wherein the anode of the diode D3 is electrically connected to the control end of the field effect transistor Q1, and the cathode of the diode D3 is electrically connected to the collector of the transistor T2.

4. The circuit for adjusting the turn-on rate of a power device based on a Miller platform according to claim 1, characterized in that: The sampling unit (2) comprises a resistor R1 and a capacitor C1, one end of the resistor R1 is electrically connected to the output end of the field effect transistor Q1, the other end of the resistor R1 is electrically connected to the input end of the field effect transistor Q1 through the capacitor C1, and the two ends of the resistor R1 are electrically connected to the first input end and the second input end of the sampling and conditioning unit respectively.

5. The circuit for adjusting the turn-on rate of a power device based on a Miller platform according to claim 1, characterized in that: A diode D1 is also included, the output end of the first driving unit is electrically connected to the anode of the diode D1, and the cathode of the diode D1 is electrically connected to the control end of the field effect transistor Q1.

6. The circuit for adjusting the turn-on rate of a power device based on a Miller platform according to claim 5, characterized in that: A turn-on resistor Ron is also included. The cathode of the diode D1 is electrically connected to one end of the turn-on resistor Ron, and the other end of the turn-on resistor Ron is electrically connected to the control end of the field effect transistor Q1.

7. The circuit for adjusting the turn-on rate of a power device based on a Miller platform according to claim 1, characterized in that: It also includes a diode D2, wherein the anode of the diode D2 is electrically connected to the control end of the field effect transistor Q1, and the cathode of the diode D2 is electrically connected to the output end of the first driving unit.

8. The circuit for adjusting the turn-on rate of a power device based on a Miller platform according to claim 7, characterized in that: A turn-off resistor Roff is also included. The anode of the diode D2 is electrically connected to one end of the turn-off resistor Roff, and the other end of the turn-off resistor Roff is electrically connected to the control end of the field effect transistor Q1.

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