A resonant auxiliary circuit for improving the driving reliability of power devices

Abstract

The present invention discloses a resonant auxiliary circuit for improving the driving reliability of power devices, belonging to the technical field of driving of power electronic devices. The resonant auxiliary driving circuit includes capacitors C<subgt;q< / subgt>, C<subgt;p< / subgt>, resistors R<subgt;q< / subgt>, R<subgt;p< / subgt>, diodes VD<subgt;1< / subgt>, VD<subgt;2< / subgt>, VD<subgt;3< / subgt>, a zener diode VD<subgt;z< / subgt> and an inductor Lr. By the ratio of the resistors R<subgt;q< / subgt> and R<subgt;p< / subgt>, voltage division of the capacitors C<subgt;q< / subgt> and C<subgt;p< / subgt> can be achieved, so that the power supply module can perform negative voltage turn-off and positive voltage turn-on only with positive voltage power supply. The resonant auxiliary circuit can effectively suppress the forward crosstalk and reverse crosstalk voltage spikes, thus ensuring the reliable operation of the power device at a higher switching frequency. Compared with the traditional driving method, the present invention can work at a higher switching speed and reduce the switching loss.

Description

Technical Field

[0001] The present invention belongs to the technical field of driving power devices, and in particular relates to a resonant auxiliary circuit for improving the driving reliability of power devices. Background Art

[0002] With the rapid development of power electronics and computer technology in recent years, electric drive technology based on power devices and power converter control has been increasingly widely applied to various aspects of the national economy, such as electric vehicles, high-speed railways, industrial robots, and CNC machine tools. Power device drive technology is one of the core elements of power converter control, and its reliability directly affects the healthy operation and performance of the power converter and even the electric drive system.

[0003] In recent years, electric drive technology has been increasingly developing towards high power, high speed, and high dynamics. This has placed higher demands on power devices and their drive technologies. High-switching-speed power devices are increasingly favored, and the introduction of wide-bandgap materials and devices has accelerated this development trend. For example, SiC materials offer advantages such as high bandgap width, high breakdown field strength, and high saturation rate. Therefore, SiC MOSFETs offer higher switching speeds, lower on-resistance, lower junction temperatures, and extremely low tail current compared to Si-based devices. This significantly improves dynamic performance, reduces the size and weight of the device, and achieves higher operating efficiency.

[0004] However, the pursuit of high speed and high dynamics inevitably leads to a technical challenge in power device applications. High switching speeds subject power devices to high dv / dt and di / dt. These spurious parameters, which are not noticeable at low frequencies, can generate voltage and current oscillations and spikes that can harm the normal operation of the electric drive system. For SiC MOSFETs, which have a low turn-on voltage threshold and allow for negative gate-source voltage, the crosstalk caused by high dv / dt and di / dt becomes even more severe.

[0005] In order to reduce the negative effects caused by crosstalk under high-dynamic control, it is necessary to suppress the crosstalk phenomenon in the drive circuit of the power device. The currently widely used methods can be roughly divided into three categories: (1) Connecting a capacitor in parallel between the gate and source. By increasing the equivalent capacitance between the gate and source, the magnitude of the spikes caused by crosstalk can be curbed. This method has a simple design and good crosstalk suppression effect. However, it will affect the switching speed of the power device, is not conducive to the high-speed turn-on of the power device, and will also increase the turn-on and turn-off losses. (2) Using an active gate drive. By actively turning on the auxiliary transistor, an additional auxiliary capacitor is connected in parallel between the gate and source, so as to actively suppress during crosstalk, without affecting the switching speed. However, due to the complexity of control, most active gate circuits are relatively complex and have a high design difficulty. (3) Negative voltage turn-off and multilevel drive. In addition to the positive voltage (turn-on) and zero voltage (steady-state turn-off), a negative voltage is added for the turn-off process, that is, multilevel drive. Using negative voltage turn-off can effectively improve the turn-off speed and can also suppress the positive turn-on crosstalk. However, a problem that follows is that a larger negative voltage spike will be caused at the turn-off moment of the other complementary power transistor in the bridge arm, which may seriously break down the power device in severe cases.

[0006] Therefore, in view of the above technical problems, it is necessary to innovate the current drive method of the power device to reduce the positive and negative voltage spikes caused by crosstalk during the high-speed switching process. Summary of the Invention

[0007] The present invention proposes a resonant auxiliary circuit for improving the drive reliability of a power device in view of the shortcomings of the prior art, which can effectively suppress the crosstalk spikes caused by the high-speed switching of the power device.

[0008] The technical solution adopted by the present invention is: a resonant auxiliary circuit for improving the drive reliability of a power device, and the resonant auxiliary circuit is arranged between the drive IC of the power device and the gate drive resistor R g ;

[0009] The resonant auxiliary circuit includes a resistor R q , a resistor R p , a capacitor C q , a capacitor C p , a diode VD1, a diode VD2, a diode VD3, a zener diode VD z and an inductor L r ;

[0010] The resistor R q , the capacitor C q are connected in parallel with the diode VD1, and one end is connected to the output end of the drive IC, and the other end is connected to the gate drive resistor R g ; The parallel-connected resistor R p and the capacitor C p are connected to the zener diode VD zAfter being connected in parallel, it is connected in series in reverse with diode VD2 and connected in parallel to gate drive resistor R g branch; the inductor L r is connected in series with diode VD3 and then connected in parallel to gate drive resistor R g branch, the resistor R p , capacitor C p , zener diode VD z and inductor L r The common terminal of is connected to the reference potential point.

[0011] Preferably, the power device is a silicon-based or silicon carbide-based IGBT, MOSFET, and GaN.

[0012] Preferably, the working timing of the resonant auxiliary circuit includes three stages: turn-on pre-charging stage, forward crosstalk suppression stage, and reverse crosstalk suppression stage.

[0013] The turn-on pre-charging stage corresponds to the [0-t0] interval of the working timing. The drive chip continuously supplies a turn-on signal to charge the loop, so that the capacitors C p , C q reach the initial voltage, where the voltage division value is determined by the resistance ratio of R q , R p That is, after stabilization, the capacitor voltages are respectively:

[0014]

[0015]

[0016] In the formula, V Cp , V Cq are the voltages on capacitors C p , C q respectively, and V GG is the power supply voltage provided by the drive chip. Adjusting the resistance ratio of R p and R q can adjust the turn-on voltage and turn-off voltage of the power device. After pre-charging, the gate voltage satisfies V gs_L = V Cp + V d , where V d is the on-state voltage drop of diodes VD1 and VD2. At this time, VD3 is not conducting due to the reverse voltage, and the power device is in a steady-state conducting state.

[0017] The forward crosstalk suppression stage corresponds to the [t0-t4] interval of the working timing. When the turn-off signal comes, the output voltage of the drive chip drops to 0V, and diode VD2 is turned off by the reverse voltage of capacitor C p , because capacitor C pis much larger than the gate capacitance, and the capacitance voltage remains approximately unchanged during the turn-off process. At this time, capacitor C q provides a negative voltage for the gate, enabling the power device to turn off quickly. At the same time, through C q -L r -VD3 loop, the energy of capacitor C q transfers to inductor L r , causing its negative voltage to gradually reach zero. By adjusting the energy transfer time, an appropriate negative voltage can be provided to weaken the positive crosstalk peak value when the positive crosstalk occurs.

[0018] The reverse crosstalk suppression stage corresponds to the interval [t5 - t7] of the working timing. As the energy of capacitor C q continually transfers to inductor L r , the voltage of capacitor C q keeps decreasing. When it is lower than the forward conduction voltage drop V d of diode VD1, VD1 conducts. Under the clamping effect of the diode, capacitor C q endures a reverse voltage equal to the diode voltage drop, and the inductor freewheels through diodes VD1 and VD3, releasing energy. Meanwhile, the gate voltage is paralleled by capacitor C q . By designing capacitor C q to be much larger than the parasitic capacitance C gs of the power device, the gate voltage can be clamped to prevent mis-conduction. When the reverse crosstalk occurs, capacitor C q provides a positive voltage equal to the diode conduction voltage drop for the gate. The slightly positively charged capacitor C q can effectively suppress the negative voltage spike and protect the gate of the power device from breakdown.

[0019] The interval [t7 - t8] of the working timing is the pre-charging stage for the next turn-on. The power supply voltage V GG of the driving chip charges capacitor C p , enabling the gate voltage to rise quickly to V Cp +V d . At the same time, capacitor C q is charged by the loop V GG -C q -VD2-VD z in preparation for the next turn-off. The voltage of the zener diode VD z is V z . After the charging of capacitor C q is completed, the voltage is V Cq =V GG -V z -V d . Therefore, by selecting an appropriate zener voltage of VD z , the turn-off negative voltage can be changed.

[0020] Beneficial effects: The present invention realizes highly reliable driving of power devices through a resonant auxiliary circuit, effectively suppressing the forward crosstalk and reverse crosstalk voltage spikes during the high-speed switching process of power devices, preventing the overvoltage risk brought by the bridge arm crosstalk phenomenon to the normal operation of the power converter. Moreover, the resonant auxiliary circuit is entirely composed of passive devices, without the need to input an additional PWM signal, and has the advantages of strong anti-interference ability and easy implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic diagram of the resonant auxiliary circuit of the present invention.

[0022] Figure 2 is the working timing diagram of the resonant auxiliary circuit.

[0023] Figs. 3(a), 3(b), and 3(c) are three working modes of the resonant auxiliary drive circuit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The technical solutions of the invention will be described in detail below in conjunction with the drawings and specific embodiments:

[0025] As Figure 1 shown, a resonant auxiliary circuit for improving the driving reliability of power devices, the resonant auxiliary circuit is arranged between the driving IC of the power device and the gate driving resistor R g ;

[0026] The resonant auxiliary circuit includes resistor R q , resistor R p , capacitor C q , capacitor C p , diode VD1, diode VD2, diode VD3, zener diode VD z and inductor L r ;

[0027] The resistor R q , capacitor C q are connected in parallel with the diode VD1, one end is connected to the output end of the driving IC, and the other end is connected to the gate driving resistor R g ; The parallel-connected resistor R p and capacitor C p are connected in parallel with the zener diode VD z , and are reversely connected in series with the diode VD2, and are connected in parallel to the gate driving resistor R g branch; The inductor L ... r is connected in series with the diode VD3 and then connected in parallel to the gate driving resistor R g [[ID=6l]]branch, the resistor R p , capacitor C p , zener diode VD z and inductor L rThe common terminal is connected to the reference potential point.

[0028] The resonant auxiliary circuit for improving the driving reliability of power devices is applicable to semiconductor power devices such as silicon-based or silicon carbide-based IGBTs, MOSFETs, and GaNs.

[0029] Figure 2 It is the working timing diagram of the resonant auxiliary circuit. The working timing of the resonant auxiliary circuit includes three stages: the turn-on pre-charging stage, the forward crosstalk suppression stage, and the reverse crosstalk suppression stage.

[0030] The turn-on pre-charging stage corresponds to the interval of [0 - t0] in the working timing. The driving chip continuously supplies a turn-on signal to charge the circuit, so that the capacitors C p , C q reach the initial voltage. The voltage division value is determined by the resistance ratio of R q , R p resistors, that is, the capacitor voltages after stabilization are respectively:

[0031]

[0032]

[0033] In the formula, V Cp , V Cq are the voltages on the capacitors C p , C q respectively, and V GG is the power supply voltage provided by the driving chip. Adjusting the resistance ratio of R p and R q can adjust the turn-on voltage and turn-off voltage of the power device. After the pre-charging is completed, the gate voltage satisfies V gs_L =V Cp +V d , where V d is the on-state voltage drop of the diodes VD1 and VD2. At this time, VD3 is not conducting due to the reverse voltage, and the power device is in a steady-state conduction state. [[ID = 51]]

[0034] [[ID = 52]]The forward crosstalk suppression stage corresponds to the interval of [t0 - t4] in the working timing. When the turn-off signal comes, the output voltage of the driving chip drops to 0V, and the conduction situation of the resonant auxiliary circuit is shown in Figure 3(a). The diode VD2 is turned off by the reverse voltage of the capacitor C [[ID = 53]] p [[ID = 54]]. Because the capacitor C [[ID = 55]] p [[ID = 56]]is much larger than the gate capacitance, the capacitor voltage is approximately unchanged during the turn-off process. At this time, the capacitor C [[ID = 57]] q [[ID = 58]]provides a negative voltage for the gate, so that the power device turns off quickly. At the same time, through the C [[ID = 59]] q [[ID = 60]]-L [[ID = 61]] r [[ID = 62]]-VD3 loop, the energy of the capacitor C [[ID = 63]] q [[ID = 64]]is transferred to the inductor L [[ID = 65]] rTransfer it so that its negative pressure gradually reaches zero. By setting the energy transfer time, an appropriate negative pressure can be provided to weaken the positive crosstalk peak value when the positive crosstalk occurs.

[0035] The reverse crosstalk suppression stage corresponds to the interval of [t5 - t7] in the working timing. The conduction condition of the resonant auxiliary circuit is shown in Fig. 3(b). As the energy of capacitor C q constantly transfers to inductor L r , the voltage of capacitor C q constantly drops. When it is lower than the forward conduction voltage drop V of diode VD1 d , VD1 conducts. Under the clamping action of the diode, capacitor C q suffers a reverse voltage equal to the voltage drop of one diode. The inductor freewheels through diodes VD1 and VD3, and the inductor releases energy. Meanwhile, the gate voltage is paralleled with capacitor C q . By designing capacitor C q to be much larger than the parasitic capacitance C of the power device gs , the gate voltage can be clamped to prevent mis-conduction. When the reverse crosstalk occurs, capacitor C q provides a positive voltage equal to the diode conduction voltage drop to the gate. The capacitor C q with a slightly positive voltage can well suppress the negative pressure spike and protect the gate of the power device from being broken down.

[0036] The interval of [t7 - t8] in the working timing is the pre-charging stage for the next turn-on. The conduction condition of the resonant auxiliary circuit is shown in Fig. 3(c). The power supply voltage V of the driving chip GG charges capacitor C p so that the gate voltage can quickly rise to V Cp +V d . At the same time, capacitor C q is charged by the loop V GG -C q -VD2-VD z to prepare for the next turn-off. The voltage of the zener diode VD z is V z . After the charging of capacitor C q is completed, the voltage is V Cq =V GG -V z -V d . Therefore, by selecting an appropriate zener voltage value of zener diode VD z , the turn-off negative pressure can be changed.

[0037] The resonant auxiliary circuit effectively suppresses the forward crosstalk and reverse crosstalk voltage spikes during the high-speed switching process of power devices, preventing the overvoltage risk brought by the bridge arm crosstalk phenomenon to the normal operation of the power converter. Moreover, the resonant auxiliary circuit is entirely composed of passive devices and does not require an additional input PWM signal, having the advantages of strong anti-interference ability and easy implementation.

[0038] The technical means disclosed in the solution of the present invention are not limited to the technical means disclosed in the above embodiments. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A resonant auxiliary circuit for improving the driving reliability of power devices, characterized in that: The resonant auxiliary circuit is disposed between the driving IC of the power device and the gate driving resistor R g ; The described resonance assistance circuit includes resistor R q , resistor R p , capacitor C q , capacitor C p , diode VD1, diode VD2, diode VD3, zener diode VD z and inductor L r ; The resistor R q , the capacitor C q are connected in parallel, one end is connected to the output end of the driving IC, and the other end is connected to the gate driving resistor R g ; The parallel-connected resistor R p and the capacitor C p are connected in parallel with the voltage regulator diode VD z , and are connected in reverse series with the diode VD2. One end of this series branch is connected to one end of R g , and the other end is connected to the reference potential point; The inductor L r is connected in series with the diode VD3, one end is connected to one end of R g , and the other end is connected to the reference potential point; The common end of the resistor R p , the capacitor C p , the voltage regulator diode VD z and the inductor L r is connected to the reference potential point; The working timing sequence of the resonant auxiliary circuit includes three stages: turn-on pre-charging stage, forward crosstalk suppression stage, and reverse crosstalk suppression stage; The turn-on pre-charge stage corresponds to the interval of [0 - t0] in the working timing sequence. By continuously supplying a turn-on signal to the circuit through the drive chip to charge the capacitor, the capacitances C p and C q reach the initial voltage, where the voltage division value is determined by the resistance ratio of R q and R p That is, after stabilization, the capacitor voltages are respectively: Wherein, V Cp and V Cq are the voltages across capacitors C p and C q respectively, and V GG is the power supply voltage provided by the driving chip; adjusting the resistance ratio of R p and R q can adjust the turn-on voltage and turn-off voltage of the power device. After pre-charging is completed, the gate voltage satisfies V gs_L = V Cp + V d , where V d is the on-state voltage drop of diodes VD1 and VD2; at this time, VD3 is not conducting due to reverse voltage, and the power device is in a steady-state conducting state; The forward crosstalk suppression phase corresponds to the [t0-t4] interval of the working sequence. When the shutdown signal comes, the output voltage of the driver chip drops to 0V, and the diode VD2 is connected to the capacitor C p Reverse voltage shutdown, due to capacitor C p Much larger than the gate capacitance, the capacitor voltage remains approximately unchanged during the shutdown process; at this time, the capacitor C q Provide negative voltage to the gate to quickly turn off the power device; at the same time, through C q -L r -VD3 circuit, capacitor C q The energy is transferred to the inductor L r Transfer, so that the negative pressure gradually reaches zero; by adjusting its energy transfer time, when the positive crosstalk comes, it provides appropriate negative pressure to weaken the positive crosstalk peak value; The reverse crosstalk suppression stage corresponds to the interval of [t5 - t7] in the working timing. As the energy of capacitor C q is continuously transferred to inductor L r , the voltage of capacitor C q keeps decreasing. After it drops below the forward conduction voltage drop V of diode VD1 d , VD1 conducts. Under the clamping effect of the diode, capacitor C q endures a reverse voltage equal to the voltage drop of a diode. The inductor freewheels through diodes VD1 and VD3, releasing energy. Meanwhile, the gate voltage is paralleled with capacitor C q . By designing capacitor C q to be much larger than the parasitic capacitance C of the power device gs , the gate voltage is clamped to prevent mis-conduction. When reverse crosstalk occurs, capacitor C q provides a positive voltage equal to the conduction voltage drop of the diode to the gate. Capacitor C q with a slightly positive voltage can suppress the negative voltage spike and protect the gate of the power device from breakdown; The interval of [t7 - t8] in the working timing sequence is the next turn-on pre-charging stage, and the power supply voltage V of the driving chip GG charges the capacitor C p so that the gate voltage can rise rapidly to V Cp +V d ; at the same time, the capacitor C q is charged by the loop V GG -C q -VD2 - VD z to prepare for the next turn-off. The voltage of the zener diode VD z is V z , and the voltage of the capacitor C q after charging is completed is V Cq = V GG -V z -V d ; therefore, by selecting an appropriate zener diode VD z the turn-off negative voltage can be changed by adjusting the regulated voltage value.

2. The resonant auxiliary circuit for improving the driving reliability of a power device according to claim 1, wherein: The power device is a silicon-based or silicon carbide-based IGBT, MOSFET, and GaN.

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