Junction temperature regulation circuit and junction temperature regulation method

Abstract

A junction temperature regulation circuit and a junction temperature regulation method thereof, the junction temperature regulation circuit includes a main three-terminal transistor and a current control circuit, the current control circuit is used to obtain the current difference between the load current and the preset reference current based on the load current on the main three-terminal transistor when the main three-terminal transistor is turned on; when the current difference is less than the preset first threshold current, the current of the on / off signal input to the control electrode of the main three-terminal transistor is reduced, and when the current difference is greater than the preset second threshold current, the current of the on / off signal input to the control electrode of the main three-terminal transistor is increased; the second threshold current is greater than or equal to the first threshold current. In the present disclosure, the current control circuit can not only regulate the on / off loss of the three-terminal transistor and smooth the junction temperature fluctuation, but also reduce the voltage and current oscillation during the on / off process, significantly extending the expected life of the three-terminal transistor, thereby improving the reliability of the system.

Description

Technical Field

[0001] The present invention belongs to the technical field of power electronics, and in particular relates to a junction temperature regulation circuit and a junction temperature regulation method. Background Art

[0002] With the large-scale commissioning of power electronic devices under non-steady working conditions such as aerospace, electric / hybrid vehicles, and oil exploration, the reliability of power devices has become increasingly prominent. According to the Coffin-Manson model, junction temperature fluctuation is the main cause of power device failure. Therefore, smoothing the junction temperature fluctuation of the main three-terminal transistor can effectively extend its life and improve the reliability of the main three-terminal transistor converter. Summary of the invention

[0003] In order to solve the above technical problems, the first object of the present disclosure is to provide a junction temperature regulation circuit that smoothes the junction temperature fluctuation of a main three-terminal transistor and prolongs its life and reliability.

[0004] A second objective of the present disclosure is to provide a junction temperature regulation method based on the above-mentioned junction temperature regulation circuit.

[0005] In order to achieve the first objective of the present disclosure, the technical solution adopted by the present disclosure is as follows:

[0006] A junction temperature regulating circuit, comprising:

[0007] A main three-terminal transistor, which is turned on or off based on the received on / off signal;

[0008] a current control circuit connected to the control electrode of the main three-terminal transistor, for obtaining a current difference between the load current and a preset reference current based on the load current on the main three-terminal transistor when the main three-terminal transistor is turned on; when the current difference is less than a preset first threshold current, reducing the current of the on / off signal input to the control electrode of the main three-terminal transistor; and when the current difference is greater than a preset second threshold current, increasing the current of the on / off signal input to the control electrode of the main three-terminal transistor;

[0009] The second threshold current is greater than or equal to the first threshold current.

[0010] Optionally, the current control circuit includes:

[0011] A sensor, arranged on a load loop where the main three-terminal transistor is located, the sensor being capable of obtaining a load current on the main three-terminal transistor;

[0012] A controller connected to the sensor, wherein the controller is capable of obtaining a current difference between the load current and a preset reference current based on the load current on the main three-terminal transistor, comparing the current difference with a first threshold current or a second threshold current, and sending a control signal to the execution circuit according to the comparison result;

[0013] The execution circuit is connected to the control electrode and the controller of the main three-terminal transistor respectively, and the execution circuit can reduce the current of the on / off signal input to the control electrode of the main three-terminal transistor or increase the current of the on / off signal input to the control electrode of the main three-terminal transistor according to the control signal.

[0014] Optionally, the execution circuit includes an auxiliary three-terminal transistor,

[0015] The control electrode of the auxiliary three-terminal transistor is connected to the controller,

[0016] The first electrode of the auxiliary three-terminal transistor is connected to the first electrode of the main three-terminal transistor;

[0017] A second electrode of the auxiliary three-terminal transistor is connected to a control electrode of the main three-terminal transistor.

[0018] Optionally, the execution circuit further includes a capacitor,

[0019] A first electrode of the auxiliary three-terminal transistor is connected to a first stage of the main three-terminal transistor through the capacitor.

[0020] Optionally, the controller comprises:

[0021] A calculation module, capable of obtaining a current difference between the load current and a preset reference current based on the load current on the main three-terminal transistor, comparing the current difference with a first threshold current or a second threshold current, and sending a voltage control signal to the power module according to the comparison result;

[0022] A power supply module with continuously adjustable voltage, used for adjusting the voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor according to the voltage control signal;

[0023] The sensor is connected to the execution circuit after passing through the calculation module and the power module in sequence.

[0024] Optionally, the junction temperature regulation circuit further includes an on / off circuit, and the on / off circuit can send an on / off signal to the control electrode of the main three-terminal transistor.

[0025] Optionally, the value of the reference current is the rated current of the load, the value of the first threshold current is -0.1 to -0.3 times the rated current of the load, and the value of the second threshold current is 0.1 to 0.3 times the rated current of the load.

[0026] In order to achieve the second purpose of the present disclosure, the technical solution adopted by the present disclosure is as follows:

[0027] A junction temperature regulation method based on the above junction temperature regulation circuit,

[0028] The main three-terminal transistor is turned on under the control of the on / off signal;

[0029] The current control circuit acquires a load current on the main three-terminal transistor, and obtains a current difference between the load current and a preset reference current based on the load current;

[0030] When the current difference is less than a preset first threshold current, the current control circuit reduces the current of the on / off signal input to the control electrode of the main three-terminal transistor; when the current difference is greater than a preset second threshold current, the current control circuit increases the current of the on / off signal input to the control electrode of the main three-terminal transistor; wherein the second threshold current is greater than or equal to the first threshold current.

[0031] Optionally, the current control circuit includes a sensor, a controller connected to the sensor, and an execution circuit connected to the control electrode of the main three-terminal transistor and the controller respectively, and the execution circuit includes an auxiliary three-terminal transistor;

[0032] The current control circuit reduces the current of the on / off signal input to the control electrode of the main three-terminal transistor, including: the controller increases the voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor;

[0033] The current control circuit increases the current of the on / off signal input to the control electrode of the main three-terminal transistor, including: the controller reduces the voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor.

[0034] Optionally, when the current difference is less than a preset first threshold current, the controller increases the voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor to a preset first voltage;

[0035] When the current difference is greater than a preset second threshold current, the controller reduces the voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor to a preset second voltage.

[0036] The present invention adds a current control circuit to the traditional three-terminal transistor driving circuit. When the current difference is less than a preset first threshold current, the load current is small and the conduction loss is small. The current control circuit reduces the current of the control electrode of the main three-terminal transistor, and the turn-on loss increases to compensate for the decrease in junction temperature caused by the decrease in load current. When the current difference is greater than a preset second threshold current, the load current is large and the conduction loss is large. The current of the control electrode of the main three-terminal transistor is increased, and the turn-on loss is reduced to compensate for the decrease in junction temperature caused by the decrease in load current.

[0037] The current control circuit can not only adjust the turn-on loss of the three-terminal transistor and smooth the junction temperature fluctuation, but also reduce the voltage and current oscillation during the turn-on process, significantly extending the expected life of the three-terminal transistor and thus improving the reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings illustrate exemplary embodiments of the present disclosure and together with the description serve to explain the principles of the present disclosure. These drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification.

[0039] Figure 1 This is a waveform diagram of the turn-on of the main three-terminal transistor in the present disclosure.

[0040] Figure 2 4 is a circuit schematic diagram of the junction temperature regulation circuit disclosed in the present invention.

[0041] Figure 3 It is a hysteresis control waveform diagram of the junction temperature regulation circuit disclosed in the present invention.

[0042] Figure 4 FIG. 4 is a diagram showing the turn-on loss of the main three-terminal transistor in the junction temperature regulation circuit of the present disclosure.

[0043] Figure 5 Graph 1 is a junction temperature curve of a main three-terminal transistor in the junction temperature regulation circuit disclosed in the present invention. DETAILED DESCRIPTION

[0044] The present disclosure is further described in detail below in conjunction with the accompanying drawings and implementations. It is understood that the specific implementations described herein are only used to explain the relevant content, rather than to limit the present disclosure. It should also be noted that, for ease of description, only the parts related to the present disclosure are shown in the accompanying drawings.

[0045] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in the present disclosure may be combined with each other. The present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0046] The three-terminal transistor includes a bipolar transistor (such as an IGBT) or a field effect transistor (such as a MOSFET); the three-terminal transistor includes a control electrode, a first electrode, and a second electrode, wherein the control electrode is a gate or a base, one of the first electrode and the second electrode is a source or a collector, and the other is a drain or an emitter.

[0047] See also Figure 2 As shown, some embodiments of the present disclosure provide a junction temperature regulation circuit, including a main three-terminal transistor 1 and a current control circuit 3; the current control circuit 3 is connected to the control electrode of the main three-terminal transistor 1; wherein,

[0048] A main three-terminal transistor 1 is used to turn on or off the main three-terminal transistor 1 based on a received on / off signal when the main three-terminal transistor is turned on; the main three-terminal transistor 1 can be a triode, an IGBT, a MOSFET, a BJT, etc., and the MOSFET device can be an N-type MOSFET device, a P-type MOSFET device, a SiC MOSFET or a SiMOSFET, etc.; the model can be SCT30N120, SCT3030ALHR, SCT3017AL, SCT2120AF, SCT3017ALHR, SCT3022AL, etc.

[0049] The current control circuit 3 can obtain the load current I and the preset reference current I based on the load current I on the main three-terminal transistor 1. ref The current difference

[0050] When the current difference is less than the preset first threshold current I th1 When the load current is small, the conduction loss is small, the current control circuit 3 reduces the current of the on / off signal input to the control electrode of the main three-terminal transistor 1, and the on / off loss increases to compensate for the decrease in junction temperature caused by the decrease in the load current I;

[0051] When the current difference is greater than the preset second threshold current I th2 When the load current I is large and the conduction loss is large, the current control circuit 3 increases the current of the on / off signal input to the control electrode of the main three-terminal transistor 1, and the on-loss is reduced to compensate for the decrease in junction temperature caused by the decrease in the load current I.

[0052] When the current difference is within the first threshold current I th1 and the second threshold current I th2 When the junction temperature of the main three-terminal transistor 1 is normal, the current size of the on / off signal does not change.

[0053] The second threshold current I th2 Greater than or equal to the first threshold current I th1The value of the reference current can be set to the rated current of the load, the value of the first threshold current is -0.1 to -0.3 times the rated current of the load, and the value of the second threshold current is 0.1 to 0.3 times the rated current of the load. The first threshold current I th1 and the second threshold current I th2 They can also all be 0.

[0054] The on / off signal may be provided by the on / off circuit 2, and the on / off signal output by the on / off circuit 2 may be a digital signal or an analog signal, and may include an on signal and an off signal; the on signal is a signal for turning on the main MOSFET device 1, and the off signal is a signal for turning off the main MOSFET device 1. The on / off circuit 2 is, for example, an analog gate control circuit, a PWM gate drive circuit, and the like.

[0055] In some specific embodiments, the current control circuit 3 includes a sensor 31, a controller 32 and an execution circuit 33; the controller 32 is connected to the sensor 32, and the execution circuit 33 is respectively connected to the control electrode of the main three-terminal transistor 1 and the controller 32.

[0056] The sensor 31 can obtain the load current I on the main three-terminal transistor 1; the sensor 31 can be a current sensing transistor integrated on the main three-terminal transistor 1 to detect the load current I of the main three-terminal transistor 1. The sensor 31 can also be installed on the load circuit where the main three-terminal transistor 1 is located; for example, the sensor 31 is installed on the main line where the first pole of the main three-terminal transistor 1 is located; for another example, the sensor 31 is installed on the main line where the second pole of the main three-terminal transistor 1 is located.

[0057] The controller 32 can obtain the load current I and the preset reference current I based on the load current I on the main three-terminal transistor 1. ref The current difference is compared with the first threshold current I th1 Or the second threshold current I th2 Compare, and send a control signal to the execution circuit 32 according to the comparison result; wherein, when the load current I is equal to the preset reference current I ref The current difference is less than the first threshold current I th1 When the load current I is equal to the preset reference current I ref The current difference is greater than the second threshold current I th2 When , the controller 32 sends a control signal to the execution circuit 32 to control the current of the control electrode of the main three-terminal transistor 1 to increase.

[0058] The execution circuit 33 can reduce the current of the control electrode of the main three-terminal transistor 1 or increase the current of the control electrode of the main three-terminal transistor 1 according to the control signal. When the execution circuit 33 receives the control signal for reducing the current sent by the controller 32, the execution circuit 33 controls the current of the control electrode of the main three-terminal transistor 1 to decrease; when the execution circuit 33 receives the control signal for increasing the current sent by the controller 32, the execution circuit 33 controls the current of the control electrode of the main three-terminal transistor 1 to increase.

[0059] The execution circuit 33 can be an on / off signal I that can increase or decrease the external input. on(off) The circuit needs to increase the on / off signal I received by the gate of the main three-terminal transistor. g When the current is greater than 100, the gate receives the on / off signal I g It is N times the external input on / off signal I on(off) , where N is greater than 1; when it is necessary to reduce the on / off signal I received by the gate of the main three-terminal transistor g When the current is greater than 100, the gate of the main three-terminal transistor receives the on / off signal I g It is N times the external input on / off signal I on(off) , where N is less than 1.

[0060] The execution circuit 33 can also be a switch that can shunt the external input on / off signal I on(off) The circuit is externally input with a large on / off signal I on(off) , when it is necessary to increase the on / off signal I received by the gate of the main three-terminal transistor 1 g When the current is greater than 100, the execution circuit 33 reduces the on / off signal I input to the external input. on(off) When the gate of the main three-terminal transistor 1 receives the on / off signal I g When the current is greater than 100, the execution circuit 33 increases the on / off signal I input to the external device. on(off) of diversion.

[0061] In some embodiments, in order to realize the on / off signal I by shunting gThe execution circuit 33 includes an auxiliary three-terminal transistor M, the control electrode of the auxiliary three-terminal transistor M is connected to the controller 32, the first electrode of the auxiliary three-terminal transistor M is connected to the first electrode of the main three-terminal transistor 1; the second electrode of the auxiliary three-terminal transistor M is connected to the control electrode of the main three-terminal transistor 1. The on-off signal can be shunted to the second electrode of the auxiliary three-terminal transistor M, and the magnitude of the shunted current can be adjusted by controlling the signal of the control electrode of the auxiliary three-terminal transistor M. The larger the current passing through the auxiliary three-terminal transistor M, the smaller the current of the on-off signal entering the control electrode of the main three-terminal transistor 1; the smaller the current passing through the auxiliary three-terminal transistor M, the larger the current of the on-off signal entering the control electrode of the main three-terminal transistor 1.

[0062] In some other embodiments, the controller 32 includes a computing module and a power module, and the sensor 31 is connected to the execution circuit 33 via the computing module and the power module.

[0063] Calculation module, obtains the load current I and the preset reference current I ref The current difference is compared with the first threshold current I th1 Or the second threshold current I th2 comparing, and sending a voltage control signal to the power module according to the comparison result;

[0064] A power supply module with continuously adjustable voltage is used to adjust the voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor according to a voltage control signal.

[0065] After the comparison result is obtained by the calculation module, a voltage control signal is output according to the comparison result. The power supply module outputs a control voltage for controlling the auxiliary three-terminal transistor M according to the voltage control signal. By adjusting the voltage of the control electrode of the three-terminal transistor M, the on-off signal of the external input is shunted, thereby adjusting the current entering the control electrode of the main three-terminal transistor 1, and finally adjusting the junction temperature of the main three-terminal transistor 1.

[0066] When the on / off signal is a PWM signal or an AC signal, the execution circuit 33 further includes a capacitor C1, and the first electrode of the auxiliary three-terminal transistor M is connected to the first stage of the main three-terminal transistor 1 through the capacitor C1, and the capacitor C1 is used to pass the PWM signal.

[0067] When the on / off signal is a DC signal, the execution circuit 33 does not include the capacitor C1 and is used to pass the DC on / off signal.

[0068] Combination Figure 1 , Figure 2 As shown, the junction temperature control principle of this embodiment is explained;

[0069] First, the turn-on and turn-off characteristics of the three-terminal transistor are analyzed; the present disclosure takes the main three-terminal transistor 1 and the auxiliary three-terminal transistor M as MOSFET devices as an example, analyzes the turn-on characteristics of the main three-terminal transistor 1, the control electrodes are the control electrodes of the MOSFET devices, the first electrode is the source electrode of the MOSFET device, the second electrode is the drain electrode of the MOSFET device, and the principles of the turn-on and turn-off characteristics of other three-terminal transistors are also similar to those of MOSFET devices.

[0070] At time t1, the gate drive signal of the main three-terminal transistor 1 jumps from VEE to VCC, the auxiliary three-terminal transistor M enters the saturation state, and the gate-source voltage V gs Gradually rises; at time t2, the gate-source voltage V gs Reaching the threshold voltage V th , drain current I d At t3, the gate current I d When the load current I is reached, the drain-source voltage V ds At t4, the drain-source voltage V ds Drop to the conduction voltage drop V ds(on) After time t4, the gate-source voltage V gs Continue to rise; at t5, the gate-source voltage V gs Reach VCC. When the bus voltage VDC and the load current I are constant, the turn-on loss of the main three-terminal transistor 1 can be expressed as:

[0071]

[0072] Among them, E on is the turn-on loss of the MOSFET device, V th1 is the threshold voltage, V gs1 is the gate-source voltage of the auxiliary three-terminal transistor M. a, b, c, d and k are parameters determined by the operating conditions and the main three-terminal transistor 1 and the auxiliary three-terminal transistor M. Therefore, the gate-source voltage V of the auxiliary three-terminal transistor M can be adjusted. gs1 To change the turn-on loss of the main three-terminal transistor 1.

[0073] When the auxiliary three-terminal transistor M operates in the saturation region, the current flowing through the auxiliary branch is equal to the saturation leakage current of the auxiliary three-terminal transistor M. By changing the gate-source voltage V gs1The saturation degree of the auxiliary three-terminal transistor M can be changed, thereby changing the current and turn-on loss of the auxiliary branch. When the conduction degree increases, the current flowing through the auxiliary branch increases, the gate charging current of the main three-terminal transistor 1 decreases, and the turn-on loss increases; when the conduction degree decreases, the current flowing through the auxiliary branch decreases, the gate charging current of the main three-terminal transistor 1 increases, the turn-on speed increases, and the turn-on loss decreases.

[0074] Combination Figure 2 , Figure 3 As shown, some embodiments of the present disclosure also provide a junction temperature regulation method based on the above-mentioned junction temperature regulation circuit, including:

[0075] The main three-terminal transistor 1 is turned on under the control of the on / off signal;

[0076] The current control circuit 3 obtains the load current on the main three-terminal transistor 1, and obtains the current difference between the load current and a preset reference current based on the load current;

[0077] When the current difference is less than the preset first threshold current I th1 When the load current is small, the conduction loss is small, the current control circuit 3 reduces the current of the on / off signal input to the control electrode of the main three-terminal transistor 1, and the on / off loss increases to compensate for the decrease in junction temperature caused by the decrease in the load current I;

[0078] When the current difference is greater than the preset second threshold current I th2 When the load current I is large and the conduction loss is large, the current control circuit 3 increases the current of the on / off signal input to the control electrode of the main three-terminal transistor 1, and the on-loss is reduced to compensate for the decrease in junction temperature caused by the decrease in the load current I.

[0079] The junction temperature regulation method disclosed in the present invention can not only regulate the turn-on loss of the three-terminal transistor and smooth the junction temperature fluctuation, but also reduce the voltage and current oscillation during the turn-on process, significantly prolonging the expected life of the three-terminal transistor, thereby improving the reliability of the system.

[0080] In some specific embodiments, the current control circuit 3 includes a sensor 31, a controller 32 connected to the sensor 31, and an execution circuit 33 connected to the control electrode of the main three-terminal transistor 1 and the controller 32 respectively, and the execution circuit 33 includes an auxiliary three-terminal transistor M;

[0081] The current control circuit 3 reduces the current of the on / off signal input to the control electrode of the main three-terminal transistor 1, including: the controller 32 increases the voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor M;

[0082] The current control circuit 3 increases the current of the on / off signal input to the control electrode of the main three-terminal transistor 1 , including: the controller 32 reduces the voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor M.

[0083] Based on the above method of controlling the current of the control electrode of the main three-terminal transistor 1 by the voltage regulation method, the junction temperature regulation method may specifically include:

[0084] When the current difference is less than the preset first threshold current I th1 When, that is, II ref th1 When the load current is small and the conduction loss is small, the controller 32 increases the voltage of the control electrode of the auxiliary three-terminal transistor M; the conduction degree of the auxiliary three-terminal transistor M increases, the shunt current of the execution circuit 33 increases, the gate current of the main three-terminal transistor 1 decreases, and the turn-on loss increases to compensate for the decrease in junction temperature caused by the decrease in load current. The controller 32 can increase the voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor M to a preset first voltage V gs1_high The voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor M can also be increased in a gradient manner.

[0085] When the current difference is greater than the preset second threshold current I th2 , that is, II ref >I th2 When the load current is large and the conduction loss is large, the controller 32 reduces the voltage of the control electrode of the auxiliary three-terminal transistor M. The conduction degree of the three-terminal transistor M is reduced, the shunt current of the execution circuit 33 is reduced, the gate current of the main three-terminal transistor 1 is increased, and the turn-on loss is reduced to compensate for the junction temperature rise caused by the increase in load current. The controller 32 reduces the voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor M to a preset second voltage V gs1_low The voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor M can also be reduced in a gradient manner.

[0086] Combination Figure 4 , Figure 5 As shown, in the technical solution of this embodiment, under the test conditions of 200V bus voltage and 10A load current, the opening loss adjustment range of the junction temperature regulation circuit disclosed in the present invention is 125.8μJ to 549.78μJ, which can achieve continuous adjustment in a wide range.

[0087] ​Under the conditions of bus voltage 200V and switching frequency 40kHz, when the load current effective value switches between 1.3A and 4A, the junction temperature fluctuation is reduced from 16.9°C to 11.2°C by adopting the technical solution disclosed in the present invention, which is a reduction of 33.7%. The number of remaining power cycles (proportional to the life) of the main three-terminal transistor 1 is N f From 4.94×10 8 Increased to 3.42×10 9 , which is improved by 6.92 times. Among them, parameter I ref 2.5A,I th1 -0.5A, I th2 0.5A, V gs1_high is 4.5V, V gs1_low is 2V.

[0088] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments / methods or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments / methods or examples described in this specification and the features of the different embodiments / methods or examples, unless they are contradictory.

[0089] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0090] Those skilled in the art should understand that the above embodiments are only for the purpose of clearly illustrating the present disclosure, and are not intended to limit the scope of the present disclosure. For those skilled in the art, other changes or modifications may be made based on the above disclosure, and these changes or modifications are still within the scope of the present disclosure.

Claims

1. A junction temperature regulating circuit, characterized in that: include: A main three-terminal transistor, which is turned on or off based on the received on / off signal; a current control circuit connected to the control electrode of the main three-terminal transistor, for obtaining a current difference between the load current and a preset reference current based on a load current on the main three-terminal transistor when the main three-terminal transistor is turned on; When the current difference is less than a preset first threshold current, the current of the on / off signal input to the control electrode of the main three-terminal transistor is reduced, and when the current difference is greater than a preset second threshold current, the current of the on / off signal input to the control electrode of the main three-terminal transistor is increased; The second threshold current is greater than or equal to the first threshold current; The current control circuit comprises: A sensor, arranged on a load loop where the main three-terminal transistor is located, the sensor being capable of obtaining a load current on the main three-terminal transistor; A controller connected to the sensor, wherein the controller is capable of obtaining a current difference between the load current and a preset reference current based on the load current on the main three-terminal transistor, comparing the current difference with a first threshold current or a second threshold current, and sending a control signal to the execution circuit according to the comparison result; The execution circuit is connected to the control electrode and the controller of the main three-terminal transistor respectively, and the execution circuit can reduce the current of the on / off signal input to the control electrode of the main three-terminal transistor or increase the current of the on / off signal input to the control electrode of the main three-terminal transistor according to the control signal; The execution circuit includes an auxiliary three-terminal transistor, The control electrode of the auxiliary three-terminal transistor is connected to the controller, The first electrode of the auxiliary three-terminal transistor is connected to the first electrode of the main three-terminal transistor; The second electrode of the auxiliary three-terminal transistor is connected to the control electrode of the main three-terminal transistor; The execution circuit further includes a capacitor, A first electrode of the auxiliary three-terminal transistor is connected to a first stage of the main three-terminal transistor through the capacitor.

2. The junction temperature regulating circuit according to claim 1, characterized in that: The controller comprises: A calculation module, capable of obtaining a current difference between the load current and a preset reference current based on the load current on the main three-terminal transistor, comparing the current difference with a first threshold current or a second threshold current, and sending a voltage control signal to the power module according to the comparison result; A power supply module with continuously adjustable voltage, used for adjusting the voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor according to the voltage control signal; The sensor is connected to the execution circuit after passing through the calculation module and the power module in sequence.

3. The junction temperature regulating circuit according to claim 1, wherein: The junction temperature regulating circuit further includes an on / off circuit, which can send an on / off signal to the control electrode of the main three-terminal transistor.

4. The junction temperature regulating circuit according to claim 1, wherein: The value of the reference current is the load rated current, the value of the first threshold current is -0.1 to -0.3 times the load rated current, and the value of the second threshold current is 0.1 to 0.3 times the load rated current.

5. A junction temperature regulation method based on the junction temperature regulation circuit according to any one of claims 1 to 3, characterized in that: The main three-terminal transistor is turned on under the control of the on / off signal; The current control circuit acquires a load current on the main three-terminal transistor, and obtains a current difference between the load current and a preset reference current based on the load current; When the current difference is less than a preset first threshold current, the current control circuit reduces the current of the on / off signal input to the control electrode of the main three-terminal transistor; When the current difference is greater than a preset second threshold current, the current control circuit increases the current of the on / off signal input to the control electrode of the main three-terminal transistor; wherein the second threshold current is greater than or equal to the first threshold current.

6. The junction temperature regulation method according to claim 5, characterized in that: The current control circuit includes a sensor, a controller connected to the sensor, and an execution circuit connected to the control electrode of the main three-terminal transistor and the controller respectively, and the execution circuit includes an auxiliary three-terminal transistor; The current control circuit reduces the current of the on / off signal input to the control electrode of the main three-terminal transistor, including: the controller increases the voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor; The current control circuit increases the current of the on / off signal input to the control electrode of the main three-terminal transistor, including: the controller reduces the voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor.

7. The junction temperature regulation method according to claim 6, characterized in that: When the current difference is less than a preset first threshold current, the controller increases the voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor to a preset first voltage; When the current difference is greater than a preset second threshold current, the controller reduces the voltage between the control electrode and the first electrode of the auxiliary three-terminal transistor to a preset second voltage.

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