Silicon carbide MOS transistor junction temperature measuring system based on Miller platform

Abstract

The invention provides a silicon carbide MOS transistor junction temperature measuring system based on a Miller platform, and belongs to the technical field of semiconductor device performance detection. The junction temperature measurement system comprises a current source type gate drive circuit and a junction temperature detection circuit. The output end of the current source type gate driving circuit is connected with the gate of the target MOS tube and is used for providing constant gate current for the target MOS tube and driving the target MOS tube to be switched on or switched off; the junction temperature detection circuit is used for measuring the junction temperature of the target MOS tube. The current source is adopted to drive the MOS tube to measure the junction temperature, the duration time of a Miller platform is long on the premise that the switching speed is not affected, and voltage oscillation of the Miller platform can be effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor device performance detection, and in particular to a silicon carbide MOS tube junction temperature measurement system based on a Miller platform. Background Art

[0002] With the rapid development of wide bandgap semiconductor power devices, silicon carbide MOS tubes have been widely used in various fields due to their advantages such as high switching speed and stable performance.

[0003] As a key component of the power electronic system, the health of the silicon carbide MOS tube will affect the normal operation of the entire system and needs to be monitored. Among them, overheating and thermal cycling account for the highest proportion of failure factors of silicon carbide MOS tubes, so it is necessary to monitor their junction temperature. The voltage detection method of the Miller platform is mature and has good temperature sensitivity. It is a junction temperature measurement method that is currently widely used.

[0004] In the prior art, a voltage source is usually used to drive a silicon carbide MOS tube to complete junction temperature measurement. However, due to the fast switching speed of the silicon carbide MOS tube, the Miller platform has oscillations. Therefore, a suitable driving resistor is usually switched during the junction temperature measurement period to avoid the Miller platform voltage oscillation. However, increasing the driving resistor will increase the turn-on period, thereby affecting the switching speed. Under the application conditions where the junction temperature measurement period is short, it will have a greater impact on the overall system. Summary of the invention

[0005] The embodiment of the present invention provides a junction temperature measurement system for a silicon carbide MOS tube based on a Miller platform, so as to solve the problem that in the prior art, a voltage source is used to drive the MOS tube for junction temperature measurement using the Miller platform, and the driving resistance is increased to avoid oscillation, resulting in a long switching cycle.

[0006] In a first aspect, an embodiment of the present invention provides a junction temperature measurement system for a silicon carbide MOS tube based on a Miller platform, comprising: a current source type gate drive circuit and a junction temperature detection circuit;

[0007] The output end of the current source type gate drive circuit is connected to the gate of the target MOS tube, and is used to provide a constant gate current for the target MOS tube, driving the target MOS tube to turn on or off;

[0008] The junction temperature detection circuit is used to measure the junction temperature of the target MOS tube.

[0009] Optionally, the current source type gate driving circuit includes: a pulse source, a gate current control module, a current mirror module and a current amplification module;

[0010] The input end of the gate current control module is connected to the output end of the pulse source, the first output end of the gate current control module is connected to the first input end of the current mirror module, and the second output end of the gate current control module is connected to the second input end of the current mirror module;

[0011] The output end of the current mirror module is connected to the input end of the current amplifier module, and the output end of the current amplifier module forms the output end of the current source type gate driving circuit.

[0012] Optionally, the gate current control module includes: a first PNP transistor, a first NPN transistor and an adjustable resistance unit;

[0013] The collector of the first NPN transistor forms the first output end of the gate current control module, the base of the first NPN transistor is connected to the base of the first PNP transistor to form the input end of the gate current control module, and the emitter of the first NPN transistor is connected to the emitter of the first PNP transistor and the first end of the adjustable resistance unit respectively;

[0014] The collector of the first PNP transistor forms the second output terminal of the gate current control module;

[0015] The second end of the adjustable resistance unit is connected to the first ground end.

[0016] Optionally, the adjustable resistor unit includes: a plurality of adjusting resistors and a plurality of first switches; wherein the adjusting resistors correspond to the first switches one by one;

[0017] The first ends of the respective adjusting resistors are connected to form a first end of an adjustable resistor unit;

[0018] The second end of each regulating resistor is connected to the first ground end through the corresponding first switch.

[0019] Optionally, the gate current control module further includes: a control unit;

[0020] The control unit is used to obtain the maximum on-time of the target MOS tube, determine the output current of the current source gate drive circuit according to the maximum on-time, determine the resistance value of the adjustable resistance unit according to the output current of the current source gate drive circuit, and adjust the resistance value of the adjustable resistance unit.

[0021] Optionally, the output current of the current source type gate drive circuit is calculated as:

[0022]

[0023] t≤t

[0024] sw sw_max

[0025] Among them, Qg is the gate charge required for the target MOS tube to turn on, t sw is the turn-on time of the target MOS tube, I gm is the output current of the current source type gate drive circuit, t sw_max It is the maximum turn-on time of the target MOS tube.

[0026] Optionally, the current mirror module includes: a second PNP transistor, a third PNP transistor, a second NPN transistor and a third NPN transistor;

[0027] The source of the second PNP transistor is connected to the source of the third PNP transistor and then connected to a positive DC power supply, and the gate of the second PNP transistor is respectively connected to the gate of the third PNP transistor and the drain of the second PNP transistor to form a first input end of the current mirror module;

[0028] The source of the second NPN transistor is connected to the source of the third NPN transistor and then connected to a negative DC power supply, and the gate of the second NPN transistor is respectively connected to the gate of the third NPN transistor and the drain of the second NPN transistor to form a second input end of the current mirror module;

[0029] The drain of the third PNP transistor is connected to the drain of the third NPN transistor to form an output end of the current mirror module.

[0030] Optionally, the junction temperature detection circuit includes: a common source inductor, a Miller platform trigger module, a gate-source voltage detection module, a current detection module and a main control module;

[0031] The source of the target MOS tube is connected to the second ground terminal through a common source inductor;

[0032] The first input terminal and the second input terminal of the Miller platform trigger module are respectively connected to the two ends of the common source inductor, and the output terminal of the Miller platform trigger module is connected to the enable terminal of the gate-source voltage detection module; the Miller platform trigger module is used to detect whether it enters the Miller platform period, and sends an enable signal to the gate-source voltage detection module when it detects that it enters the Miller platform period;

[0033] The first input terminal and the second input terminal of the gate-source voltage detection module are respectively connected to the gate and the source of the target MOS tube, and the output terminal of the gate-source voltage detection module is connected to the main control module; the gate-source voltage detection module is used to detect the gate-source voltage of the target MOS tube, and send the detected gate-source voltage of the target MOS tube to the main control module when receiving the enable signal;

[0034] The output end of the current detection module is connected to the main control module, and is used to detect the drain current of the target MOS tube, and send the detected drain current to the main control module;

[0035] The main control module is used to determine the junction temperature of the target MOS tube according to the gate-source voltage and drain current of the target MOS tube.

[0036] Optionally, the gate-source voltage detection module includes: a first amplifier, a second amplifier, an enabling switch, a first capacitor, a first resistor and a second resistor;

[0037] The positive input terminal of the first amplifier is connected to the first end of the first resistor and the first end of the second resistor respectively, and the negative input terminal of the first amplifier is connected to the output terminal of the first amplifier and the first end of the enable switch;

[0038] The positive input terminal of the second amplifier is respectively connected to the first terminal of the first capacitor and the second terminal of the enable switch, and the negative input terminal of the second amplifier is connected to the input terminal of the second amplifier to form the output terminal of the gate-source voltage detection module;

[0039] The second end of the first resistor forms a first input end of the gate-source voltage detection module, and the second end of the second resistor forms a second input end of the gate-source voltage detection module;

[0040] The control end of the enable switch forms an enable end of the gate-source voltage detection module;

[0041] The second end of the first capacitor and the second end of the second resistor are both connected to the first ground end.

[0042] Optionally, the Miller platform trigger module includes: a third amplifier, a first comparator, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a D trigger and a voltage regulator diode;

[0043] The positive input terminal of the third amplifier is respectively connected to the first end of the fifth resistor and the first end of the sixth resistor, the negative input terminal of the third amplifier is respectively connected to the first end of the third resistor and the first end of the fourth resistor, and the output terminal of the third amplifier is respectively connected to the second end of the fourth resistor, the cathode of the voltage stabilizing diode and the positive input terminal of the first comparator;

[0044] The amplitude input terminal of the first comparator is connected to the first terminal of the seventh resistor, and the output terminal of the first comparator is connected to the trigger terminal of the D flip-flop;

[0045] The in-phase output terminal of the D flip-flop forms the output terminal of the Miller platform trigger module, and the inverting output terminal of the D flip-flop is connected to the first ground terminal through the eighth resistor;

[0046] The second end of the seventh resistor is connected to the reference power supply;

[0047] The second end of the third resistor forms a first input end of the Miller platform trigger module, and the second end of the fifth resistor forms a second input end of the Miller platform trigger module;

[0048] The second end of the sixth resistor and the anode of the voltage-stabilizing diode are both connected to the first ground end.

[0049] The embodiment of the present invention provides a junction temperature measurement system for a silicon carbide MOS tube based on a Miller platform, which belongs to the technical field of semiconductor device performance detection. The junction temperature measurement system includes: a current source type gate drive circuit and a junction temperature detection circuit; the output end of the current source type gate drive circuit is connected to the gate of the target MOS tube, which is used to provide a constant gate current for the target MOS tube and drive the target MOS tube to be turned on or off; the junction temperature detection circuit is used to measure the junction temperature of the target MOS tube. The present invention uses a current source to drive the MOS tube to measure the junction temperature, which can extend the duration of the Miller platform by reducing the gate current without affecting the switching speed, thereby effectively reducing the Miller platform voltage oscillation while ensuring the switching speed, meeting the application requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0051] Figure 1 It is a structural schematic diagram of a silicon carbide MOS tube junction temperature measurement system based on a Miller platform provided in an embodiment of the present invention;

[0052] Figure 2 It is the conduction equivalent first-order RC circuit diagram of the voltage source type gate drive circuit;

[0053] Figure 3 It is the capacitor voltage and current waveform of the first-order RC circuit equivalent to the conduction of the voltage source type gate drive circuit;

[0054] Figure 4 It is the turn-on waveform of the voltage source type gate drive circuit;

[0055] Figure 5 is a turn-on waveform diagram of a current source type gate drive circuit provided by an embodiment of the present invention;

[0056] Figure 6 1 is a schematic diagram of a circuit structure of a current source type gate drive circuit provided by an embodiment of the present invention;

[0057] Figure 7 It is a circuit structure schematic diagram of a junction temperature detection circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0058] In order to enable people in the technical field to better understand the present solution, the technical solution in the embodiment of the present solution will be clearly described below in conjunction with the drawings in the embodiment of the present solution. Obviously, the described embodiment is an embodiment of a part of the present solution, not all of the embodiments. Based on the embodiments in the present solution, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present solution.

[0059] The term "including" and any other variations in the specification and claims of this solution and the above drawings mean "including but not limited to", and is intended to cover non-exclusive inclusions and is not limited to the examples listed in the text. In addition, the terms "first" and "second" are used to distinguish different objects, not to describe a specific order.

[0060] The following is a detailed description of the implementation of the present invention in conjunction with the specific drawings:

[0061] Figure 1 A schematic diagram of the circuit structure of a silicon carbide MOS tube junction temperature measurement system based on a Miller platform provided in an embodiment of the present invention. Figure 1 , the silicon carbide MOS tube junction temperature measurement system based on the Miller platform includes: a current source type gate drive circuit 1 and a junction temperature detection circuit;

[0062] The output end of the current source type gate driving circuit 1 is connected to the gate of the target MOS transistor Qm, and is used to provide a constant gate current for the target MOS transistor Qm, and drive the target MOS transistor Qm to be turned on or off;

[0063] The junction temperature detection circuit is used to measure the junction temperature of the target MOS tube Qm.

[0064] In the prior art, a voltage source type gate driving circuit is used to drive the target MOS tube Qm. The driving process of the voltage source type gate driving circuit can be approximated as a first-order RC circuit, such as Figure 2 As shown, it includes: the total gate resistance R of the target MOS tube Qm (that is, the sum of the gate external drive resistance and the gate internal resistance) and the gate junction capacitance C of the target MOS tube Qm.

[0065] When turned on, the DC power supply Vs starts to charge C through R. Since the initial value of the capacitor voltage is 0, it responds to the zero state. Therefore:

[0066]

[0067] Among them, V S is the power supply voltage, V C is the capacitor voltage

[0068] Based on the above, the capacitor voltage can be obtained as:

[0069]

[0070] The capacitor current is:

[0071]

[0072] Among them, the time constant τ=RC.

[0073] From the above analysis, we can see that the waveforms of capacitor voltage and capacitor current are as follows: Figure 3 As shown, it can represent the gate voltage and gate drive current of the target MOS tube Qm, which is Figure 3 It can be seen that the gate drive current is always decreasing.

[0074] When the current source type gate driving circuit 1 is used for driving, the gate driving current is constant. Figure 4 shows the turn-on waveform of the voltage source type gate drive circuit, Figure 5 The waveform diagram of the current source type gate drive circuit 1 is shown as follows (i g is the gate current, v gs is the gate-source voltage), Figure 4 and Figure 5 The difference in current between the two can also be clearly seen.

[0075] Since the gate charge required for the target MOS tube Qm to turn on is certain, when the initial gate current is the same, the gate current of the voltage source type gate drive circuit is continuously attenuated, while the gate current of the current source type gate drive circuit 1 is constant. Therefore, the time required for driving by the voltage source type gate drive circuit is longer, the switching speed is slower, and the loss is greater; the switching speed of the current source type drive circuit is faster and the loss is smaller.

[0076] More specifically, the duration of the Miller platform is actually the gate current to the Miller capacitor C gd The charging time, so when the duration of the Miller platform is the same, the gate current provided by the voltage source type gate drive circuit and the current source type gate drive circuit 1 during the Miller platform is the same. The gate current provided by the voltage source type gate drive circuit during the Miller platform is recorded as I gV , the gate current provided by the current source type gate drive circuit 1 is recorded as I g , we can get:

[0077]

[0078] I gV =I g

[0079] Among them, R g is the total gate resistance, which is the sum of the gate internal resistance and the external drive resistance. milis the current Miller voltage.

[0080] From the above analysis, it can be seen that the driving process of the voltage source type gate drive circuit can be approximated as a first-order RC circuit, the charging time is selected as 5τ, and the on-time length t of the voltage source type gate drive circuit during driving swv Can be:

[0081] t swv =5τ=R g C iss

[0082] Among them, C iss is the input capacitance of the target MOS tube Qm.

[0083] If the gate current provided by the current source type gate driving circuit 1 is constant, the conduction time t of the current source type gate driving circuit 1 during driving can be obtained. swc Can be:

[0084]

[0085] Among them, Q gd is the gate-drain charge, Q g It is the charge required for the target MOS tube Qm to turn on.

[0086] Take C3M0060065K MOS tube as an example.

[0087]

[0088] It can be seen from this that t swv >t swc .

[0089] In summary, under the same Miller platform duration, the switching process under the voltage source gate drive circuit is longer than the switching process under the current source gate drive circuit. Conversely, within the same switching cycle, the duration of the Miller platform can be longer. Since the Miller platform is equivalent to the process of charging the Miller capacitor, the smaller the current, the longer the charging time, that is, the smaller the gate current, the longer the duration of the Miller platform; therefore, in the embodiment of the present invention, the current source gate drive circuit 1 is used to drive the target MOS tube Qm, which can reduce the output current of the current source gate drive circuit 1 to increase the duration of the Miller platform, thereby effectively reducing voltage oscillation, improving the temperature sensitivity and temperature linearity of the Miller platform, and making it easier to realize online detection of junction temperature.

[0090] In one possible implementation, reference Figure 6 , the current source type gate driving circuit 1 may include: a pulse source Ve, a gate current control module 11, a current mirror module 12 and a current amplification module 13;

[0091] The input end of the gate current control module 11 is connected to the output end of the pulse source Ve, the first output end of the gate current control module 11 is connected to the first input end of the current mirror module 12, and the second output end of the gate current control module 11 is connected to the second input end of the current mirror module 12;

[0092] The output end of the current mirror module 12 is connected to the input end of the current amplifier module 13 , and the output end of the current amplifier module 13 forms the output end of the current source type gate driving circuit 1 .

[0093] The pulse source Ve is used to provide a pulse signal, the gate current control module 11 cooperates with the current mirror module 12 to output a stable driving current, and the current amplification module 13 is used to amplify the current to increase the driving capability.

[0094] In a possible implementation, the gate current control module 11 may include: a first PNP transistor Q1n, a first NPN transistor Q1p and an adjustable resistance unit 111;

[0095] The collector of the first NPN transistor Q1p forms the first output end of the gate current control module 11, the base of the first NPN transistor Q1p is connected to the base of the first PNP transistor Q1n to form the input end of the gate current control module 11, and the emitter of the first NPN transistor Q1p is connected to the emitter of the first PNP transistor Q1n and the first end of the adjustable resistance unit 111 respectively;

[0096] The collector of the first PNP transistor Q1n forms the second output terminal of the gate current control module 11;

[0097] The second end of the adjustable resistance unit 111 is connected to the first ground end.

[0098] In the embodiment of the present invention, a push-pull circuit is formed by using PNP and NPN types. The push-pull circuit can output positive current and negative current to the current mirror module 12 , and at the same time, the current size can be controlled by adjusting the resistance value of the adjustable resistance unit 111 .

[0099] Specifically, the first PNP transistor Q1n and the first NPN transistor Q1p are always in a state where one is turned on and the other is turned off. E ), the first NPN transistor Q1p is turned on, the output voltage is high, and the resistor (R1) flowing through the output electrode generates a positive current; at this time, the first NPN transistor Q1p works in the amplification area, the collector current and the emitter current are approximately equal and output to the subsequent circuit, and the output current i c1p The size is:

[0100]

[0101] When the pulse signal is at a low level, the first PNP transistor Q1n is turned on and outputs a negative current to the subsequent circuit. The output current i c1n The size is:

[0102]

[0103] In a possible implementation, the adjustable resistor unit 111 may include: a plurality of adjusting resistors Rm and a plurality of first switches K1; wherein the adjusting resistors Rm correspond to the first switches K1 one by one;

[0104] The first ends of the adjusting resistors Rm are connected to form a first end of the adjustable resistor unit 111;

[0105] The second end of each regulating resistor Rm is connected to the first ground end through the corresponding first switch K1.

[0106] In order to obtain different Miller platform durations, the adjustable resistance unit 111 in the embodiment of the present invention is provided with multiple first switches K1 and multiple adjustment resistors Rm, and different resistance values ​​are obtained by controlling the on and off of each first switch K1, thereby obtaining different gate currents and adjusting the duration of the Miller platform.

[0107] For further reference, Figure 4 Each first switch K1 may also be a one-to-many switch, where only one regulating resistor Rm is connected each time, and each regulating resistor Rm has a different resistance value.

[0108] In a possible implementation, the gate current control module 11 may further include: a control unit;

[0109] The control unit is used to obtain the maximum on-time of the target MOS tube Qm, determine the output current of the current source gate drive circuit 1 according to the maximum on-time, determine the resistance value of the adjustable resistance unit 111 according to the output current of the current source gate drive circuit 1, and adjust the resistance value of the adjustable resistance unit 111.

[0110] In the embodiment of the present invention, a control unit is further provided to control each first switch K1 and adjust the resistance value of the adjustable resistance unit 111 so that the gate current control module 11 outputs a suitable current, thereby obtaining a suitable Miller platform duration.

[0111] In one possible implementation, reference Figure 6 , the current mirror module 12 may include: a second PNP transistor Q2n, a third PNP transistor Q3n, a second NPN transistor Q2p and a third NPN transistor Q3p;

[0112] The source of the second PNP transistor Q2n is connected to the source of the third PNP transistor Q3n and then connected to the positive DC power supply V EE The gate of the second PNP transistor Q2n is connected to the gate of the third PNP transistor Q3n and the drain of the second PNP transistor Q2n to form a first input terminal of the current mirror module 12;

[0113] The source of the second NPN transistor Q2p is connected to the source of the third NPN transistor Q3p and then connected to the negative DC power supply V CC The gate of the second NPN transistor Q2p is connected to the gate of the third NPN transistor Q3p and the drain of the second NPN transistor Q2p to form a second input terminal of the current mirror module 12;

[0114] The drain of the third PNP transistor Q3 n is connected to the drain of the third NPN transistor Q3 p to form an output end of the current mirror module 12 .

[0115] The function of the current mirror module 12 is to make the output current equal to the input current so that the output current is easier to control. The embodiment of the present invention uses a mirror circuit composed of two identical transistors, the transistors work in the amplification region, and the output current is equal to the input current.

[0116] For example, when the pulse signal is at a high level, the upper push-pull outputs a forward current, and the second PNP transistor Q2n and the third PNP transistor Q3n in the upper bridge arm start to work. The base currents of the two transistors are equal, the voltages between the base and the emitter are equal, and the collector currents are also equal, that is, the output current i w =i c1p .

[0117] When the pulse signal is at a low level, the upper push-pull outputs a negative current, and the two transistors in the lower bridge arm start working, and the output current i w =i c1n , thereby outputting a stable current.

[0118] Furthermore, the current amplification module 13 is used to amplify the current to increase the driving capability, including: a fourth PNP transistor Q4n and a fourth NPN transistor Q4p, etc., for specific reference Figure 6 .

[0119] When the pulse signal is at a high level, the front stage outputs a forward current, the fourth NPN transistor Q4p is turned on, and the resistor R p The voltage on i w R p Since the output power required by the circuit is relatively large, it is necessary to use a transistor with a relatively high power. The conduction voltage drop of such a transistor is relatively large and cannot be ignored.

[0120] V Rg =i w R p -V BE(on)

[0121] Flowing through R p The current is:

[0122]

[0123] According to KCL, the output gate current is as follows:

[0124]

[0125] The same is true when the pulse signal is at a low level. From the above, it can be seen that the output current is amplified.

[0126] In a possible implementation, the calculation formula for the output current of the current source type gate driving circuit 1 may be:

[0127]

[0128] t≤t

[0129] sw sw_max

[0130] Among them, Q g is the gate charge required for the target MOS tube Qm to turn on, t sw is the turn-on time of the target MOS tube Qm, I gm is the output current of the current source type gate drive circuit 1, t sw_max It is the maximum turn-on time of the target MOS tube Qm.

[0131] Based on the above analysis, since the Miller platform is equivalent to the process of charging the Miller capacitor, we can get:

[0132]

[0133] Since there is a limit on the maximum on-time of the MOS tube during junction temperature detection, in the embodiment of the present invention, the duration of the Miller platform can be increased by reducing the gate current within the maximum limit time, thereby avoiding oscillation and increasing temperature sensitivity and temperature linearity.

[0134] In one possible implementation, reference Figure 7 , the junction temperature detection circuit may include: a common source inductor Lks, a Miller platform trigger module 21, a gate-source voltage detection module 22, a current detection module and a main control module;

[0135] The source of the target MOS tube Qm is connected to the second ground terminal through the common source inductor Lks;

[0136] The first input terminal and the second input terminal of the Miller platform trigger module 21 are respectively connected to the two ends of the common source inductor Lks, and the output terminal of the Miller platform trigger module 21 is connected to the enable terminal of the gate-source voltage detection module 22; the Miller platform trigger module 21 is used to detect whether it enters the Miller platform period, and sends an enable signal to the gate-source voltage detection module 22 when it detects that it enters the Miller platform period;

[0137] The first input terminal and the second input terminal of the gate-source voltage detection module 22 are respectively connected to the gate and the source of the target MOS tube Qm, and the output terminal of the gate-source voltage detection module 22 is connected to the main control module; the gate-source voltage detection module 22 is used to detect the gate-source voltage of the target MOS tube Qm, and send the detected gate-source voltage of the target MOS tube Qm to the main control module when receiving the enable signal;

[0138] The output end of the current detection module is connected to the main control module, and is used to detect the drain current of the target MOS tube Qm, and send the detected drain current to the main control module;

[0139] The main control module is used to determine the junction temperature of the target MOS tube Qm according to the gate-source voltage and the drain current of the target MOS tube Qm.

[0140] In the embodiment of the present invention, the target MOS tube Qm is connected in series with the common source inductor Lks. During the process of turning on the target MOS tube Qm, the voltage of the common source inductor Lks is less than 0 in the current rising stage, the voltage of the common source inductor Lks is equal to 0 when entering the Miller platform, and oscillation occurs when leaving the Miller platform, and the voltage of the common source inductor Lks is greater than 0. Therefore, in the embodiment of the present invention, the Miller platform trigger module 21 can be used to detect whether the Miller platform is entered, so as to control the gate-source voltage detection module 22 to perform sampling and transmit it to the main control module.

[0141] Similarly, the current sampling module can use the current sensor to sample the drain current, and the main control module controls the current sensor to sample the drain current at the PWM midpoint.

[0142] The opened Miller platform is sampled at a fixed period, and the main control module extracts the current dynamic junction temperature according to the sampling information and the multi-dimensional model of VM-Tj-IL calibrated offline (the Miller platform voltage at different temperatures and load currents is measured offline to form a multi-dimensional model).

[0143] In one possible implementation, reference Figure 7 , the gate-source voltage detection module 22 includes: a first amplifier APM1, a second amplifier AMP2, an enable switch EN, a first capacitor C1, a first resistor R1 and a second resistor R2;

[0144] The positive input terminal of the first amplifier APM1 is connected to the first end of the first resistor R1 and the first end of the second resistor R2 respectively, and the negative input terminal of the first amplifier APM1 is connected to the output terminal of the first amplifier APM1 and the first end of the enable switch EN;

[0145] The positive input terminal of the second amplifier AMP2 is respectively connected to the first terminal of the first capacitor C1 and the second terminal of the enable switch EN, and the negative input terminal of the second amplifier AMP2 is connected to the input terminal of the second amplifier AMP2 to form the output terminal of the gate-source voltage detection module 22;

[0146] The second end of the first resistor R1 forms a first input end of the gate-source voltage detection module 22 , and the second end of the second resistor R2 forms a second input end of the gate-source voltage detection module 22 ;

[0147] The control end of the enable switch EN forms the enable end of the gate-source voltage detection module 22;

[0148] The second end of the first capacitor C1 and the second end of the second resistor R2 are both connected to the first ground end.

[0149] The first resistor R1 and the second resistor R2 are used for voltage division, the first amplifier APM1 and the second amplifier AMP2 are used for amplifying the signal, and the enable switch EN is used for controlling the sampling output.

[0150] In one possible implementation, reference Figure 7 The Miller platform trigger module 21 includes: a third amplifier AMP3, a first comparator CMP1, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a D trigger U1 and a voltage stabilizing diode D1;

[0151] The positive input terminal of the third amplifier AMP3 is respectively connected to the first end of the fifth resistor R5 and the first end of the sixth resistor R6, the negative input terminal of the third amplifier AMP3 is respectively connected to the first end of the third resistor R3 and the first end of the fourth resistor R4, and the output terminal of the third amplifier AMP3 is respectively connected to the second end of the fourth resistor R4, the cathode of the voltage stabilizing diode D1 and the positive input terminal of the first comparator CMP1;

[0152] An amplitude input terminal of the first comparator CMP1 is connected to a first terminal of a seventh resistor R7, and an output terminal of the first comparator CMP1 is connected to a trigger terminal of a D flip-flop;

[0153] The in-phase output terminal of the D flip-flop U1 forms the output terminal of the Miller platform trigger module 21, and the inverting output terminal of the D flip-flop U1 is connected to the first ground terminal through the eighth resistor R8;

[0154] A second end of the seventh resistor R7 is connected to a reference power source Vref;

[0155] The second end of the third resistor R3 forms the first input end of the Miller platform trigger module 21, and the second end of the fifth resistor R5 forms the second input end of the Miller platform trigger module 21;

[0156] The second end of the sixth resistor R6 and the anode of the voltage-stabilizing diode D1 are both connected to the first ground end.

[0157] Based on the above analysis, during the turn-on process of the target MOS tube Qm, the voltage of the common source inductor Lks is less than 0 during the current rising stage, the voltage of the common source inductor Lks is equal to 0 when entering the Miller platform, and oscillation occurs when leaving the Miller platform, and the voltage of the common source inductor Lks is greater than 0. Therefore, in the embodiment of the present invention, the D trigger U1 is used to identify the Miller platform, generate an enable signal to control the enable switch EN, extract sampling information, and realize junction temperature detection.

[0158] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A silicon carbide MOS tube junction temperature measurement system based on a Miller platform, characterized in that: include: Current source type gate drive circuit and junction temperature detection circuit; The output end of the current source type gate driving circuit is connected to the gate of the target MOS tube, and is used to provide a constant gate current for the target MOS tube, so as to drive the target MOS tube to be turned on or off; The junction temperature detection circuit is used to measure the junction temperature of the target MOS tube.

2. The silicon carbide MOS tube junction temperature measurement system based on the Miller platform according to claim 1, characterized in that: The current source type gate driving circuit comprises: a pulse source, a gate current control module, a current mirror module and a current amplification module; The input end of the gate current control module is connected to the output end of the pulse source, the first output end of the gate current control module is connected to the first input end of the current mirror module, and the second output end of the gate current control module is connected to the second input end of the current mirror module; The output end of the current mirror module is connected to the input end of the current amplification module, and the output end of the current amplification module forms the output end of the current source type gate driving circuit.

3. The silicon carbide MOS tube junction temperature measurement system based on the Miller platform according to claim 2, characterized in that: The gate current control module includes: a first PNP transistor, a first NPN transistor and an adjustable resistance unit; The collector of the first NPN transistor forms the first output end of the gate current control module, the base of the first NPN transistor is connected to the base of the first PNP transistor to form the input end of the gate current control module, and the emitter of the first NPN transistor is respectively connected to the emitter of the first PNP transistor and the first end of the adjustable resistance unit; The collector of the first PNP transistor forms the second output terminal of the gate current control module; The second end of the adjustable resistance unit is connected to the first ground end.

4. The silicon carbide MOS tube junction temperature measurement system based on the Miller platform according to claim 3, characterized in that: The adjustable resistor unit includes: a plurality of adjusting resistors and a plurality of first switches; wherein the adjusting resistors correspond to the first switches one by one; The first ends of the respective adjusting resistors are connected to form a first end of the adjustable resistor unit; The second end of each regulating resistor is connected to the first ground end through a corresponding first switch.

5. The silicon carbide MOS tube junction temperature measurement system based on the Miller platform according to claim 3, characterized in that: The gate current control module further includes: a control unit; The control unit is used to obtain the maximum turn-on time of the target MOS tube, determine the output current of the current source type gate drive circuit according to the maximum turn-on time, determine the resistance value of the adjustable resistance unit according to the output current of the current source type gate drive circuit, and adjust the resistance value of the adjustable resistance unit.

6. The silicon carbide MOS tube junction temperature measurement system based on the Miller platform according to claim 5, characterized in that: The calculation formula of the output current of the current source type gate drive circuit is: t≤t sw sw_max Among them, Q g is the gate charge required for the target MOS tube to turn on, t sw is the opening time of the target MOS tube, I gm is the output current of the current source type gate drive circuit, t sw_max is the maximum turn-on duration of the target MOS tube.

7. The silicon carbide MOS tube junction temperature measurement system based on the Miller platform according to claim 2, characterized in that: The current mirror module includes: a second PNP transistor, a third PNP transistor, a second NPN transistor and a third NPN transistor; The source of the second PNP transistor is connected to the source of the third PNP transistor and then connected to a positive DC power supply, and the gate of the second PNP transistor is respectively connected to the gate of the third PNP transistor and the drain of the second PNP transistor to form a first input end of the current mirror module; The source of the second NPN transistor is connected to the source of the third NPN transistor and then connected to a negative DC power supply, and the gate of the second NPN transistor is respectively connected to the gate of the third NPN transistor and the drain of the second NPN transistor to form a second input end of the current mirror module; The drain of the third PNP transistor is connected to the drain of the third NPN transistor to form the output end of the current mirror module.

8. The silicon carbide MOS tube junction temperature measurement system based on the Miller platform according to any one of claims 1 to 7, characterized in that: The junction temperature detection circuit includes: a common source inductor, a Miller platform trigger module, a gate-source voltage detection module, a current detection module and a main control module; The source of the target MOS tube is connected to the second ground terminal through the common source inductor; The first input terminal and the second input terminal of the Miller platform trigger module are respectively connected to the two ends of the common source inductor, and the output terminal of the Miller platform trigger module is connected to the enable terminal of the gate-source voltage detection module; the Miller platform trigger module is used to detect whether it enters the Miller platform period, and sends an enable signal to the gate-source voltage detection module when it detects that it enters the Miller platform period; The first input terminal and the second input terminal of the gate-source voltage detection module are respectively connected to the gate and the source of the target MOS tube, and the output terminal of the gate-source voltage detection module is connected to the main control module; the gate-source voltage detection module is used to detect the gate-source voltage of the target MOS tube, and send the detected gate-source voltage of the target MOS tube to the main control module when receiving the enable signal; The output end of the current detection module is connected to the main control module, and is used to detect the drain current of the target MOS tube, and send the detected drain current to the main control module; The main control module is used to determine the junction temperature of the target MOS tube according to the gate-source voltage and the drain current of the target MOS tube.

9. The silicon carbide MOS tube junction temperature measurement system based on the Miller platform according to claim 8, characterized in that: The gate-source voltage detection module includes: a first amplifier, a second amplifier, an enabling switch, a first capacitor, a first resistor and a second resistor; The positive input terminal of the first amplifier is connected to the first end of the first resistor and the first end of the second resistor respectively, and the negative input terminal of the first amplifier is connected to the output terminal of the first amplifier and the first end of the enable switch; The positive input terminal of the second amplifier is respectively connected to the first terminal of the first capacitor and the second terminal of the enable switch, and the negative input terminal of the second amplifier is connected to the input terminal of the second amplifier to form the output terminal of the gate-source voltage detection module; The second end of the first resistor forms a first input end of the gate-source voltage detection module, and the second end of the second resistor forms a second input end of the gate-source voltage detection module; The control end of the enable switch forms the enable end of the gate-source voltage detection module; The second end of the first capacitor and the second end of the second resistor are both connected to the first ground end.

10. The silicon carbide MOS tube junction temperature measurement system based on the Miller platform according to claim 8, characterized in that: The Miller platform trigger module includes: a third amplifier, a first comparator, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a D trigger and a voltage stabilizing diode; The positive input terminal of the third amplifier is respectively connected to the first end of the fifth resistor and the first end of the sixth resistor, the negative input terminal of the third amplifier is respectively connected to the first end of the third resistor and the first end of the fourth resistor, and the output terminal of the third amplifier is respectively connected to the second end of the fourth resistor, the cathode of the voltage stabilizing diode and the positive input terminal of the first comparator; The amplitude input terminal of the first comparator is connected to the first end of the seventh resistor, and the output terminal of the first comparator is connected to the trigger terminal of the D flip-flop; The in-phase output terminal of the D flip-flop forms the output terminal of the Miller platform trigger module, and the inverting output terminal of the D flip-flop is connected to the first ground terminal through the eighth resistor; The second end of the seventh resistor is connected to a reference power supply; The second end of the third resistor forms the first input end of the Miller platform trigger module, and the second end of the fifth resistor forms the second input end of the Miller platform trigger module; The second end of the sixth resistor and the anode of the voltage-stabilizing diode are both connected to the first ground end.

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