Switching Circuit

Abstract

The present application relates to a switching circuit. The switching circuit comprises: a switching transistor, wherein the switching transistor comprises a control electrode, a first transmission electrode and a second transmission electrode, and the switching transistor controls the on or off of the switching transistor by controlling the voltage or current from the control electrode to the first transmission electrode; and a feedback circuit, wherein the feedback circuit is configured to provide a first feedback when the switching transistor switches from the off state to the on state, and the feedback circuit is configured to provide a second feedback when the switching transistor switches from the on state to the off state. The rate of change of the forward voltage or forward current from the second transmission electrode to the first transmission electrode over time is adjusted according to the feedback circuit.

Description

Technical Field

[0001] The present application relates to power electronics technology, and in particular to a switching circuit. Background Art

[0002] Semiconductor switching devices are widely used as main power switching devices in the switching power supply industry. However, during the high-speed switching process of the switching device, if the voltage or current changes too quickly per unit time, that is, the rate of change of the voltage or current over time is too high, it will cause strong electromagnetic interference (EMI). Electromagnetic compatibility (EMC) testing measures the ability of the tested device to not generate EMI to other devices while not being affected by EMI from other devices. The EMI generated by the switching device during high-speed switching will cause EMC to exceed the standard.

[0003] In the prior art, in order to reduce the EMI generated by the switching device during high-speed switching, thereby optimizing the radiation emission (RE) test, the typical approach is to slow down the switching speed of the switching device by increasing the driving resistance to reduce EMI. However, increasing the driving resistance cannot change the time of the Miller platform, but can only affect the speed before and after the Miller platform. The length of the Miller platform time is strongly correlated with the RE test results and is also a key factor in determining the switching speed. The length of the Miller platform time is affected by the size of the Miller capacitance. The larger the Miller capacitance, the longer the Miller platform time. However, the increase in Miller capacitance will increase the turn-on loss and is not conducive to improving the performance of the switching device.

[0004] Semiconductor switching devices used in power supply networks must also consider the problem of electrical surge, which is the peak voltage and current that instantly exceeds the stable value. Due to environmental factors such as lightning or electrical equipment start-stop failures, switching devices may face voltage and current amplitudes far exceeding normal values ​​in a short period of time, causing device performance degradation, equipment failure, or complete equipment destruction.

[0005] Therefore, a technical solution is needed that can reduce the EMI generated by the switching device during high-speed switching while minimizing the impact on the performance of the switching device, and has safety and reliability during transient conditions such as surges and static electricity. Summary of the invention

[0006] The purpose of the present application is to provide a switching circuit. The switching circuit includes: a switching transistor, wherein the switching transistor includes a control electrode, a first transmission electrode and a second transmission electrode, and the switching transistor controls the switching of the switching transistor between an on state and an off state by controlling the voltage or current from the control electrode to the first transmission electrode; and a feedback circuit, wherein the feedback circuit is configured to provide a first feedback when the switching transistor switches from the off state to the on state, and the feedback circuit is configured to provide a second feedback when the switching transistor switches from the on state to the off state. The rate of change of the forward voltage or forward current from the second transmission electrode to the first transmission electrode over time is adjusted according to the feedback circuit. In this way, different feedback is provided by the feedback circuit to adjust the rate of change of the forward voltage or forward current over time, which is conducive to reducing the electromagnetic radiation interference caused by the drastic change of voltage and current at the moment of opening, while not affecting the shutdown performance.

[0007] In the first aspect, an embodiment of the present application provides a switching circuit. The switching circuit includes: a switching transistor, wherein the switching transistor includes a control electrode, a first transmission electrode, and a second transmission electrode, and the switching transistor controls the switching of the switching transistor between an on state and an off state by controlling the voltage or current from the control electrode to the first transmission electrode; and a feedback circuit, wherein the feedback circuit is configured to provide a first feedback when the switching transistor switches from the off state to the on state, and the feedback circuit is configured to provide a second feedback when the switching transistor switches from the on state to the off state. The rate of change of the forward voltage or forward current from the second transmission electrode to the first transmission electrode over time is adjusted according to the feedback circuit.

[0008] The technical solution described in the first aspect provides different feedbacks through the feedback circuit to adjust the rate of change of the forward voltage or forward current over time, which is beneficial to reduce the electromagnetic radiation interference caused by the drastic changes in voltage and current at the moment of turning on, while not affecting the shutdown performance.

[0009] According to the first aspect, in a possible implementation, the switching transistor controls the switching between an on state and an off state by controlling the voltage from the control electrode to the first transmission electrode, the first feedback and the second feedback are both voltage feedback, the feedback circuit is connected between the control electrode and the second transmission electrode, and when the switching transistor switches from the off state to the on state, the rate of change of the forward voltage of the switching transistor under the action of the first feedback over time is a first rate, and when the switching transistor switches from the on state to the off state, the rate of change of the forward voltage of the switching transistor under the action of the second feedback over time is a second rate.

[0010] In this way, the voltage feedback provided by the feedback circuit is used to adjust the rate of change of the forward voltage over time, so that the switching circuit can achieve adjustable voltage change rate through the voltage-type control device.

[0011] According to the first aspect, in a possible implementation, the feedback circuit includes: a capacitor, a resistor, and a diode. The resistor and the diode are connected in parallel between the capacitor and the switch transistor. When the switch transistor is switched from the off state to the on state, the diode is configured to be forward-conducted so that the capacitor is connected between the control electrode and the second transmission electrode without passing through the resistor. When the switch transistor is switched from the on state to the off state, the diode is configured to be reverse-cutoff so that the capacitor and the resistor are connected in series between the control electrode and the second transmission electrode.

[0012] In this way, the configuration of the capacitor, the resistor and the diode enables the feedback circuit to provide different voltage feedbacks respectively when the switch transistor switches from the off state to the on state or from the on state to the off state.

[0013] According to the first aspect, in a possible implementation, the feedback circuit includes: a capacitor, a resistor, and a switch. The resistor and the switch are connected in parallel between the capacitor and the switching transistor. The switch is closed before the switching transistor switches from the off state to the on state so that the capacitor is connected between the control electrode and the second transmission electrode without passing through the resistor. The switch is opened before the switching transistor switches from the on state to the off state so that the capacitor and the resistor are connected in series between the control electrode and the second transmission electrode.

[0014] In this way, the configuration of the capacitor, the resistor and the switch realizes that the feedback circuit provides different voltage feedbacks respectively when the switch transistor switches from the off state to the on state or from the on state to the off state.

[0015] According to the first aspect, in a possible implementation, the feedback circuit includes: a first capacitor, a second capacitor, and a third capacitor, wherein each of the first capacitor, the second capacitor, and the third capacitor has one end connected to each other; a resistor; and a diode. The resistor and the diode are connected in parallel between the other end of the first capacitor and the control electrode. The other end of the second capacitor is connected to the second transmission electrode, and the other end of the third capacitor is connected to the first transmission electrode. When the voltage from the control electrode to the first transmission electrode is greater than the threshold voltage, the switch transistor is turned on so that the voltage of the second transmission electrode decreases so that the diode is forward-conducted, so that the first capacitor and the second capacitor are connected in series between the control electrode and the second transmission electrode without passing through the resistor. When the voltage from the control electrode to the first transmission electrode is less than the threshold voltage, the switch transistor is turned off so that the voltage of the second transmission electrode increases so that the diode is reversely turned off, so that the first capacitor, the second capacitor, and the resistor are connected in series between the control electrode and the second transmission electrode.

[0016] In this way, the feedback circuit provides different voltage feedbacks respectively when the switch transistor switches from the off state to the on state or from the on state to the off state through the configuration of multiple capacitors, resistors and diodes.

[0017] According to the first aspect, in a possible implementation, the feedback circuit includes: a first capacitor, a second capacitor, and a third capacitor, wherein each of the second capacitor and the third capacitor has one end connected to each other, and one end of the first capacitor is connected to the control electrode of the switch transistor; a resistor; and a diode. The resistor and the diode are connected in parallel to the other end of the first capacitor and are connected between the second capacitor and the third capacitor. The other end of the second capacitor is connected to the second transmission electrode, and the other end of the third capacitor is connected to the first transmission electrode. When the voltage from the control electrode to the first transmission electrode is greater than the threshold voltage, the switch transistor is turned on so that the voltage of the second transmission electrode decreases so that the diode is forward-conducted, so that the first capacitor and the second capacitor are connected in series between the control electrode and the second transmission electrode without passing through the resistor. When the voltage from the control electrode to the first transmission electrode is less than the threshold voltage, the switch transistor is turned off so that the voltage of the second transmission electrode increases so that the diode is reversely turned off, so that the first capacitor, the second capacitor and the resistor are connected in series between the control electrode and the second transmission electrode.

[0018] In this way, the feedback circuit provides different voltage feedbacks respectively when the switch transistor switches from the off state to the on state or from the on state to the off state through the configuration of multiple capacitors, resistors and diodes.

[0019] According to the first aspect, in a possible implementation, when the switching transistor switches from the off state to the on state, the capacitor is connected in parallel with the Miller capacitance of the switching transistor between the control electrode and the second transmission electrode, thereby reducing the rate of change of the forward voltage over time.

[0020] In this way, by connecting the capacitor in parallel with the Miller capacitor, the Miller capacitor is equivalently increased, thereby affecting the Miller platform and reducing the rate of change of voltage over time.

[0021] According to the first aspect, in a possible implementation manner, when the switch transistor switches from the on state to the off state, the capacitor and the resistor form a charging loop between the control electrode and the second transmission electrode.

[0022] In this way, the shutdown performance is not affected.

[0023] According to the first aspect, in a possible implementation, when the switching transistor switches from the off state to the on state, the first capacitor and the second capacitor are connected in series and then connected in parallel with the parasitic capacitance between the control electrode and the second transmission electrode between the control electrode and the second transmission electrode, thereby reducing the rate of change of the forward voltage over time.

[0024] In this way, the Miller capacitance is equivalently increased, thereby affecting the Miller platform and reducing the rate of change of the forward voltage over time.

[0025] According to the first aspect, in a possible implementation, when the switching transistor switches from the on state to the off state, the first capacitor, the second capacitor, the third capacitor and the resistor constitute a charging loop between the control electrode and the second transmission electrode.

[0026] In this way, the shutdown performance is not affected.

[0027] According to the first aspect, in a possible implementation manner, the diode is configured to block a surge voltage of the second transmission electrode relative to the control electrode so as to provide surge blocking protection for the switching transistor.

[0028] In this way, surge blocking protection is provided for the switching transistor.

[0029] According to the first aspect, in a possible implementation manner, an anode of the diode is connected to the control electrode, a cathode of the diode is connected to one end of the capacitor, and the other end of the capacitor is connected to the second control electrode.

[0030] In this way, it is achieved that the diode has different configurations when the switching transistor switches from the off state to the on state or from the on state to the off state.

[0031] According to the first aspect, in a possible implementation manner, a cathode of the diode is connected to the second control electrode, an anode of the diode is connected to one end of the capacitor, and the other end of the capacitor is connected to the control electrode.

[0032] In this way, it is achieved that the diode has different configurations when the switching transistor switches from the off state to the on state or from the on state to the off state.

[0033] According to the first aspect, in a possible implementation manner, the second capacitor and the third capacitor form a voltage divider loop between the second transmission electrode and the first transmission electrode.

[0034] In this way, the voltage drop of the feedback voltage applied to the diode is regulated through the voltage divider circuit, so that a low-voltage device can be selected as the diode.

[0035] According to the first aspect, in a possible implementation, the switching transistor controls the switching of the switching transistor between an on state and an off state by controlling the current from the control electrode to the first transmission electrode, the first feedback and the second feedback are both current feedback, the feedback circuit is connected between the control electrode and the first transmission electrode, and when the switching transistor switches from the off state to the on state, the rate of change of the forward current of the switching transistor under the action of the first feedback over time is a third rate, and when the switching transistor switches from the on state to the off state, the rate of change of the forward current of the switching transistor under the action of the second feedback over time is a fourth rate.

[0036] In this way, the current feedback provided by the feedback circuit can adjust the rate of change of the forward current over time, so that the switching circuit can achieve adjustable current change rate through the current-type control device.

[0037] According to the first aspect, in a possible implementation, the feedback circuit includes: a first capacitor, a second capacitor, and a third capacitor, wherein each of the first capacitor, the second capacitor, and the third capacitor has one end connected to each other; a resistor, wherein one end of the resistor is connected to the control electrode, and the other end of the resistor is connected to the other end of the first capacitor; and a diode. The cathode of the diode is connected to the other end of the first capacitor, and the anode of the diode is connected to the base of the current signal amplifier. The other end of the second capacitor is connected to the second transmission electrode, and the other end of the third capacitor is connected to the first transmission electrode. The emitter of the current signal amplifier is connected to the control electrode, and the collector of the current signal amplifier is connected to the first transmission electrode. When the voltage from the control electrode to the first transmission electrode is greater than the threshold voltage, the diode is forward-conducted so that the first capacitor and the second capacitor are connected in series between the base of the current signal amplifier and the second transmission electrode without passing through the resistor, and the discharge current flowing through the first capacitor is amplified by the current signal amplifier to enhance the feedback of the input current of the control electrode. When the voltage from the control electrode to the first transmission electrode is less than the threshold voltage, the diode is reversely cut off so that the first capacitor, the second capacitor and the resistor are connected in series between the control electrode and the second transmission electrode.

[0038] In this way, the feedback circuit provides different current feedbacks respectively for the switching transistor switching from the off state to the on state or from the on state to the off state through the configuration of multiple capacitors, resistors and diodes.

[0039] According to the first aspect, in a possible implementation, the feedback circuit includes: a sampling resistor, wherein one end of the sampling resistor is connected to the first transmission electrode, the other end of the sampling resistor is grounded, and the voltage change of the sampling resistor corresponds to the change of the forward current; and an amplifier. The input end of the amplifier is connected to both ends of the sampling resistor, the output end of the amplifier is coupled to the base of the current signal amplifier, the emitter of the current signal amplifier is grounded, and the collector of the current signal amplifier is connected to the control electrode. The change of the forward current flowing from the second transmission electrode to the first transmission electrode is amplified by the amplifier to enhance the feedback of the input current of the control electrode.

[0040] In this way, the current change is sampled by the sampling resistor and amplified by the amplifier, so that the feedback circuit provides different current feedbacks for the switching transistor switching from the off state to the on state or from the on state to the off state.

[0041] According to the first aspect, in a possible implementation manner, the current signal amplifier is a triode.

[0042] In this way, the current signal is amplified through the transistor, which is conducive to enhancing feedback.

[0043] According to the first aspect, in a possible implementation, the switching transistor is a metal oxide semiconductor field effect transistor MOSFET, and the control electrode, the first transmission electrode and the second transmission electrode of the switching transistor correspond to the gate, source and drain of the MOSFET respectively.

[0044] In this way, a circuit design of a switching circuit or a switching device with improved switching interference is achieved by using MOSFET.

[0045] According to the first aspect, in a possible implementation, the switching transistor is an insulated gate bipolar transistor IGBT, and the control electrode, the first transmission electrode and the second transmission electrode of the switching transistor correspond to the control electrode, the emitter and the collector of the IGBT respectively.

[0046] In this way, a circuit design of a switching circuit or a switching device with improved switching interference is achieved by using the IGBT.

[0047] According to the first aspect, in a possible implementation manner, the switch transistor is a high electron mobility transistor (HEMT), and the control electrode, the first transmission electrode and the second transmission electrode of the switch transistor correspond to the gate, source and drain of the HEMT respectively.

[0048] In this way, a circuit design of a switching circuit or a switching device with improved switching interference is achieved by using the HEMT.

[0049] According to the first aspect, in a possible implementation manner, the HEMT is a gallium nitride GaN HEMT.

[0050] In this way, a circuit design of a switching circuit or a switching device with improved switching interference is achieved by using the GaN HEMT.

[0051] According to the first aspect, in a possible implementation manner, the switching transistor is a silicon controlled rectifier SCR, and the control electrode, the first transmission electrode and the second transmission electrode of the switching transistor correspond to the control electrode, anode and cathode of the SCR respectively.

[0052] In this way, a circuit design of a switching circuit or a switching device with improved switching interference is achieved by means of the SCR.

[0053] According to the first aspect, in a possible implementation manner, a photovoltaic power supply system includes the switching circuit.

[0054] In this way, the EMI of the photovoltaic system in high-speed switching is reduced.

[0055] According to the first aspect, in a possible implementation manner, an uninterruptible power supply UPS includes the switch circuit.

[0056] In this way, the EMI of the uninterruptible power supply in high-speed switching is reduced.

[0057] According to the first aspect, in a possible implementation manner, an inverter includes the switching circuit.

[0058] In this way, the EMI of the inverter in high-speed switching is reduced.

[0059] According to the first aspect, in a possible implementation manner, a frequency converter includes the switching circuit.

[0060] In this way, the EMI of the frequency converter during high-speed switching is reduced.

[0061] According to the first aspect, in a possible implementation manner, an on-vehicle power supply device includes the switching circuit.

[0062] In this way, the EMI of the vehicle power supply device in high-speed switching is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to illustrate the technical solutions in the embodiments of the present application or the background technology, the drawings required for use in the embodiments of the present application or the background technology will be described below.

[0064] Figure 1 A structural block diagram of a switch circuit provided in an embodiment of the present application is shown.

[0065] Figure 2 A circuit schematic diagram of a switch circuit according to an implementation method provided in an embodiment of the present application is shown.

[0066] Figure 3 A circuit schematic diagram of a switch circuit in another implementation manner provided in an embodiment of the present application is shown.

[0067] Figure 4 A circuit schematic diagram of a switch circuit in another implementation manner provided in an embodiment of the present application is shown.

[0068] Figure 5 A circuit schematic diagram of a switch circuit in another implementation manner provided in an embodiment of the present application is shown.

[0069] Figure 6 A circuit schematic diagram of a switch circuit in another implementation manner provided in an embodiment of the present application is shown.

[0070] Figure 7 A circuit schematic diagram of a switch circuit in another implementation manner provided in an embodiment of the present application is shown.

[0071] Figure 8 A circuit schematic diagram of a switch circuit in another implementation manner provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0072] The embodiment of the present application provides a switching circuit. The switching circuit includes: a switching transistor, wherein the switching transistor includes a control electrode, a first transmission electrode and a second transmission electrode, and the switching transistor controls the switching of the switching transistor between an on state and an off state by controlling the voltage or current from the control electrode to the first transmission electrode; and a feedback circuit, wherein the feedback circuit is configured to provide a first feedback when the switching transistor switches from the off state to the on state, and the feedback circuit is configured to provide a second feedback when the switching transistor switches from the on state to the off state. The rate of change of the forward voltage or forward current from the second transmission electrode to the first transmission electrode over time is adjusted according to the feedback circuit. In this way, different feedback is provided by the feedback circuit to adjust the rate of change of the forward voltage or forward current over time, which is conducive to reducing the electromagnetic radiation interference caused by the drastic change of voltage and current at the moment of opening, while not affecting the shutdown performance.

[0073] The embodiments of the present application can be used in the following application scenarios: high-speed switching devices, EMC test equipment, RE test equipment, electrical equipment used in power supply networks, and other application scenarios that require reducing EMI during high-speed switching or improving radiation effects, including but not limited to photovoltaic power supply systems, uninterruptible power supplies (UPS), inverters, frequency converters, and vehicle-mounted power supply equipment.

[0074] The embodiments of the present application can be adjusted and improved according to the specific application environment and are not specifically limited here.

[0075] In order to enable those skilled in the art to better understand the present application, the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0076] See also Figure 1 , Figure 1 FIG. 1 shows a structural block diagram of a switch circuit provided in an embodiment of the present application. Figure 1As shown, the switch transistor 100 includes a control electrode 102, a first transmission electrode 104 and a second transmission electrode 106. In a possible implementation, the switch transistor 100 is a voltage-controlled transistor, and the forward current from the second transmission electrode 106 to the first transmission electrode 104 can be controlled to be turned on and off by controlling the voltage from the control electrode 102 to the first transmission electrode 104. A feedback circuit 108 is connected between the control electrode 102 and the second transmission electrode 106, and the feedback circuit 108 is configured to feed back the voltage change between the second transmission electrode 106 and the first transmission electrode 104 (for example, through the potential change of the second transmission electrode 106) to the control electrode 102. The feedback circuit 108 provides different degrees of feedback according to whether the switch transistor 100 is in a turn-on transient state (turn-on moment) of switching from an off state to an on state or a turn-off transient state (turn-off moment) of switching from an on state to an off state. It should be understood that the on-state and off-state of the switching transistor mentioned in the embodiment of the present application refer to the stable working state, while the on-transient state and the off-transient state refer to the transition process of the on-moment and the off-moment, respectively. When the switching transistor is turned on, it means switching from the off-state to the on-state, corresponding to the switch opening moment, and when the switching transistor is turned off, it means switching from the on-state to the off-state, corresponding to the switch turning off moment. Specifically, when the switching transistor 100 switches from the off-state to the on-state, that is, the on-transient state of the switching transistor 100 can be divided into four stages. The first stage: the voltage from the control electrode 102 to the first transmission electrode 104 is gradually increased and reaches the first threshold voltage relative to the control electrode 102 and the first transmission electrode 104. The forward current from the second transmission electrode 106 to the first transmission electrode 104 is zero in the first stage, that is, it is cut off. The second stage: the voltage from the control electrode 102 to the first transmission electrode 104 exceeds the first threshold voltage and continues to increase, the voltage from the control electrode 102 to the second transmission electrode 106 is less than the second threshold voltage between the control electrode 102 and the second transmission electrode 106, and the forward current begins to increase in the second stage. The third stage: the voltage from the control electrode 102 to the second transmission electrode 106 reaches the second threshold voltage, and under the influence of the Miller effect, the voltage from the control electrode 102 to the first transmission electrode 104 reaches saturation, the forward current reaches saturation, and the forward voltage from the second transmission electrode 106 to the first transmission electrode 104 continues to decrease. The fourth stage: the voltage from the control electrode 102 to the first transmission electrode 104 continues to increase, the forward current remains saturated, and the forward voltage continues to decrease. Among them, the length of time that the switch transistor 100 is in the third stage, that is, the length of time that it is affected by the Miller effect, determines the turn-on speed of the switch transistor 100, which can also be understood as the rate of decrease of the forward voltage from the second transmission electrode 106 to the first transmission electrode 104.When the switch transistor 100 is in the third stage of the turn-on transient state, the feedback provided by the feedback circuit 108 can reduce the rate of decrease of the forward voltage, thereby equivalently extending the period during which the switch transistor 100 is in the Miller effect, that is, the time during which the forward current and the voltage from the control electrode 102 to the first transmission electrode 104 are both in saturation, thereby slowing down the turn-on speed of the switch transistor 100, which is beneficial to reducing the electromagnetic radiation interference generated at the turn-on moment.

[0077] Please continue reading Figure 1, when the switch transistor 100 switches from the on state to the off state, that is, the off transient state of the switch transistor 100 can also be divided into multiple stages, and the off speed of the switch transistor 100 is also affected by the rate of change of the forward voltage. When the switch transistor 100 is in the off transient state, the feedback provided by the feedback circuit 108 should avoid the influence of the decrease of the rate of change of the forward voltage of the switch transistor 100 as much as possible, so as to maintain a high off speed of the switch transistor 100, thereby shortening the overall on and off cycle of the switch transistor 100, which is conducive to reducing the electromagnetic radiation interference generated at the moment of turning on while maintaining a high switching speed. Therefore, the feedback circuit 108 provides different feedbacks for the switch transistor 100 in the on transient state of switching from the off state to the on state or the off transient state of switching from the on state to the off state. Specifically, the feedback circuit 108 may include a first feedback loop and a second feedback loop. When the switch transistor 100 is turned on, that is, in the turn-on transient state from the off state to the on state, the first feedback loop is turned on and the second feedback loop is turned off; when the switch transistor 100 is turned off, that is, in the turn-off transient state from the on state to the off state, the first feedback loop is turned off and the second feedback loop is turned on. The feedback provided by the first feedback loop is greater than the feedback provided by the second feedback loop, so that the rate of change of the forward voltage from the second transmission electrode 106 to the first transmission electrode 104 under the action of the first feedback loop is less than the rate of change of the forward voltage under the action of the second feedback loop. The feedback loop 108 can also switch between the first feedback state and the second feedback state. When the switch transistor 100 is turned on, that is, in the turn-on transient state from the off state to the on state, the feedback loop 108 is in the first feedback state; when the switch transistor 100 is turned off, that is, in the turn-off transient state from the on state to the off state, the feedback loop 108 is in the second feedback state. The feedback provided by the feedback loop 108 in the first feedback state is greater than the feedback provided by the feedback loop 108 in the second feedback state, so that the rate of change of the forward voltage from the second transmission electrode 106 to the first transmission electrode 104 when the feedback loop 108 is in the first feedback state is smaller than the rate of change of the forward voltage when the feedback loop 108 is in the second feedback state. In this way, when the switch transistor 100 is at the turn-on moment, that is, the turn-on transient state, the rate of change of the forward voltage from the second transmission electrode 106 to the first transmission electrode 104 with time is smaller than the rate of change of the forward voltage with time when the switch transistor 100 is at the turn-off moment, that is, the turn-off transient state, so that the EMI generated when the switch transistor 100 is turned on can be reduced while not affecting the turn-off performance of the switch transistor 100.

[0078] Please continue reading Figure 1Whether the switch transistor 100 is in the on-state or off-state can be determined based on the voltage from the control electrode 102 to the first transmission electrode 104, or based on the voltage from the control electrode 102 to the second transmission electrode 106. The control of the first feedback loop and the second feedback loop by the feedback loop 108, or the switching of the first feedback state and the second feedback state, can be based on the voltage change from the control electrode 102 to the first transmission electrode 104, or based on the voltage change from the control electrode 102 to the second transmission electrode 106.

[0079] Please continue reading Figure 1 , the control electrode 102 of the switch transistor 100 is externally manifested as an external control electrode 112, the first transmission electrode 104 is externally manifested as an external first transmission electrode 114, and the second transmission electrode 106 is externally manifested as an external second transmission electrode 116. That is, the combination of the switch transistor 100 and the feedback circuit 108 can be externally manifested as a switch circuit 110. The switch circuit 110 has three external ports, namely, the external control electrode 112, the external first transmission electrode 114 and the external second transmission electrode 116. When the switch transistor 100 is a voltage-controlled type, the switch circuit 110 is a voltage-controlled type circuit, that is, by controlling the voltage from the external control electrode 112 to the external first transmission electrode 114, the current from the external second transmission electrode 116 to the external first transmission electrode 114 can be controlled to be turned on and off. Due to the influence of the feedback circuit 108, the switch circuit 110 has a slower turn-on speed at the turn-on moment, thereby having smaller electromagnetic radiation interference, and the turn-off speed at the turn-off moment is greater than the turn-on speed at the turn-on moment, thereby maintaining a shorter turn-on and turn-off cycle as a whole.

[0080] Please continue reading Figure 1 The Miller effect is caused by the Miller capacitance of the switch transistor 100, that is, the parasitic capacitance between the control electrode 102 and the second transmission electrode 106. During the turn-on process of the switch transistor 100, the electricity stored in the parasitic capacitance needs to be neutralized before the switch transistor 100 is fully turned on, so it will cause turn-on loss. In some exemplary embodiments, the feedback loop 108 can be configured by configuring a capacitor in parallel with the Miller capacitance between the control electrode 102 and the second transmission electrode 106, thereby equivalently increasing the Miller capacitance, thereby extending the time when the switch transistor 100 is in the Miller effect period, slowing down the turn-on speed of the switch transistor 100, and helping to reduce the electromagnetic radiation interference generated at the turn-on moment.

[0081] In some exemplary embodiments, the switch transistor 100 is a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). The control electrode 102, the first transmission electrode 104 and the second transmission electrode 106 of the switch transistor 100 correspond to the gate, source and drain of the MOSFET respectively.

[0082] In some exemplary embodiments, the switch transistor 100 is an insulated gate bipolar transistor (IGBT). The control electrode 102, the first transmission electrode 104 and the second transmission electrode 106 of the switch transistor 100 correspond to the control electrode or gate electrode, the emitter electrode and the collector electrode of the IGBT respectively.

[0083] In some exemplary embodiments, the switch transistor 100 is a high electron mobility transistor (HEMT), also known as a modulation-doped FET (MODFET), or a two-dimensional electron gas field effect transistor (2-DEGFET), or a selectively doped heterojunction transistor (SDHT). The control electrode 102, the first transmission electrode 104, and the second transmission electrode 106 of the switch transistor 100 correspond to the gate, source, and drain of the HEMT, respectively. In a possible implementation, the HEMT is a gallium nitride GaN HEMT.

[0084] In some exemplary embodiments, the switching transistor 100 may also adopt other types of semiconductor switching devices, such as a power transistor (Giant Transistor, GTR), an insulated gate bipolar transistor (Insulated Gate Bipolar Transistor, IGBT), a gate turn-off thyristor (GTO), a thyristor (Thyristor) is also called a silicon controlled rectifier (Silicon Controlled Rectifier, SCR) or other suitable devices.

[0085] In some exemplary embodiments, the switch transistor 100 is a silicon controlled rectifier (SCR), and the control electrode, the first transmission electrode, and the second transmission electrode of the switch transistor 100 correspond to the control electrode, the anode, and the cathode of the SCR, respectively.

[0086] See also Figure 2 , Figure 2 FIG. 1 shows a circuit schematic diagram of a switch circuit according to an implementation method provided by an embodiment of the present application. Figure 2 As shown, the switching circuit 200 includes a capacitor C1, a resistor R1, a diode D1, a switching transistor Q1 and a parasitic body diode D0 of the switching transistor Q1. Although the parasitic body diode D0 has a separate reference numeral, it should be regarded as an inherent part of the switching transistor Q1. Among them, the resistor R1 and the diode D1 are connected in parallel between the capacitor C1 and the gate G of the switching transistor Q1. The capacitor C1 is connected to the drain D of the switching transistor Q1. The anode of the diode D1 is connected to the gate G of the switching transistor Q1, and the cathode is connected to the capacitor C1. The capacitor C1, the resistor R1 and the diode D1 constitute a feedback circuit between the gate G and the drain D of the switching transistor Q1.

[0087] Please continue reading Figure 2 , the switch transistor Q1 switches from the off state to the on state, that is, the on transient state of the switch transistor Q1 can be divided into four stages. The first stage: the voltage V from the gate G to the source S GS Gradually increase and reach the first threshold voltage V between the gate G and the source S TH1 , the forward current I from the drain D to the source S DS In the first stage, it is zero, that is, it is cut off. The second stage: the voltage V from the gate G to the source S GS Exceeds the first threshold voltage V TH1 And continue to increase, the voltage V from gate G to drain D GD Less than the second threshold voltage V between the gate G and the drain D TH2 , forward current I DS In the second stage, it starts to increase. The third stage: the voltage V from the gate G to the drain D GD Reaching the second threshold voltage V TH2 , affected by the Miller effect, the voltage V from the gate G to the source S GS When the forward current I reaches saturation, DS reaches saturation, and the forward voltage V from drain D to source S DS The fourth stage: the voltage V from the gate G to the source S GS Continue to increase, the forward current I DS To maintain saturation, the forward voltage V DSThe switching transistor Q1 is in the third stage, that is, the time it is affected by the Miller effect determines the turn-on speed of the switching transistor Q1, which can also be understood as the forward voltage V from the drain D to the source S. DS When the switch tube Q1 is in the third stage, affected by the Miller effect, the voltage V from the gate G to the source S GS Saturation is reached, which is manifested as a curve shape that remains unchanged over time, corresponding to the Miller platform.

[0088] Please continue reading Figure 2 The feedback circuit composed of capacitor C1, resistor R1 and diode D1 provides different feedback for the switching transistor Q1 in the turn-on transient state when switching from the turn-off state to the turn-on state or the turn-off transient state when switching from the turn-on state to the turn-off state. Specifically, when the switching transistor Q1 is turned on, that is, the voltage V from the gate G to the source S is GS Switch to high level, then diode D1 is in forward conduction state, so R1 connected in parallel with diode D1 is equivalent to being short-circuited. In this way, when switching transistor Q1 is turned on, capacitor C1 is connected between drain D and gate G, which is equivalent to being connected in parallel with Miller capacitance (parasitic capacitance between gate G and drain D) of switching transistor Q1 between gate G and drain D, thereby equivalently increasing Miller capacitance and reducing forward voltage V DS The rate of decline slows down the turn-on speed of the switching transistor Q1, which is beneficial to reduce the electromagnetic radiation interference generated at the moment of turn-on. When the switching transistor is turned off, that is, the voltage V from the gate G to the source S GS Switches to a low level, at which time the diode D1 is in a reverse cutoff state, so the capacitor C1 and the resistor R1 are connected in series between the drain D and the gate G. It should be understood that when the switch transistor Q1 is turned on, the capacitor C1 is in a discharge state during the Miller plateau period, and its discharge current flows from the capacitor C1 to the drain D, thereby causing a portion of the input current of the gate G to be diverted, thereby causing the voltage V between the gate G and the source S to be GS Reach saturation. Conversely, when the switch transistor Q1 is turned off, the capacitor C1 is in a charging state and the charging current flows from the drain D to the capacitor C1. At this time, due to the influence of the resistor R1 connected in series with the capacitor C1, the charging process of the capacitor C1 has little effect on the turn-off speed of the switch transistor Q1. In this way, when the switch transistor Q1 is turned on, that is, in the transient state, the forward voltage V from the drain D to the source S is DS The rate of change over time is less than the forward voltage V when the switching transistor Q1 is turned off, that is, in the off transient state. DSThe rate of change over time can reduce the EMI generated when the switch transistor Q1 is turned on while not affecting the turn-off performance. Among them, whether the switch transistor Q1 is in the turn-on transient state or the turn-off state can be determined according to the voltage V from the gate G to the source S GS It can be judged based on the voltage V from the gate G to the drain D GD judge.

[0089] Please continue reading Figure 2 When a surge event occurs, the potential of the drain D of the switching transistor Q1 may increase significantly. At this time, the diode D1 will be in a reverse cut-off state, thereby preventing the high voltage of the drain D of the switching transistor Q1 from being connected to the gate G of the switching transistor Q1 through the capacitor C1 and causing damage to the switching transistor Q1, thereby avoiding adverse effects on the cut-off performance of the transistor.

[0090] Figure 2 The switching transistor Q1 shown is an N-channel enhancement MOSFET. In some exemplary embodiments, the switching transistor Q1 may adopt other types of MOSFETs (such as P-channel enhancement MOSFET or N-channel depletion MOSFET), or may adopt other types of semiconductor switching devices, such as GTR, IGBT, GTO, SCR or other suitable devices, and configure the parasitic body diode accordingly.

[0091] See also Figure 2 In some exemplary embodiments, the diode D1 can be implemented by using appropriate means in the prior art, such as using a point contact type, a surface contact type or a planar type diode. These can be adjusted and improved according to the specific application environment and are not specifically limited here.

[0092] See also Figure 2 In some exemplary embodiments, the capacitor C1 can be implemented by using appropriate means in the prior art. These can be adjusted and improved according to the specific application environment and are not specifically limited here.

[0093] See also Figure 3 , Figure 3 FIG. 2 shows a circuit schematic diagram of a switch circuit according to another implementation method provided in an embodiment of the present application. Figure 3As shown, the switching circuit 300 includes a capacitor C1, a resistor R1, a diode D1, a switching transistor Q1 and a parasitic body diode D0 of the switching transistor Q1. Although the parasitic body diode D0 has a separate reference numeral, it should be regarded as an inherent part of the switching transistor Q1. Among them, the resistor R1 and the diode D1 are connected in parallel between the capacitor C1 and the drain D of the switching transistor Q1. The capacitor C1 is connected to the gate G of the switching transistor Q1. The cathode of the diode D1 is connected to the drain D of the switching transistor Q1, and the anode is connected to the capacitor C1. The capacitor C1, the resistor R1 and the diode D1 constitute a feedback circuit between the gate G and the drain D of the switching transistor Q1.

[0094] Please continue reading Figure 3 The feedback circuit composed of capacitor C1, resistor R1 and diode D1 provides different feedback for the switching transistor Q1 in the turn-on transient state when switching from the turn-off state to the turn-on state or the turn-off transient state when switching from the turn-on state to the turn-off state. Specifically, when the switching transistor Q1 is turned on, that is, the voltage V from the gate G to the source S is GS Switch to high level, then diode D1 is in forward conduction state, so R1 connected in parallel with diode D1 is equivalent to being short-circuited. In this way, when switching transistor Q1 is turned on, capacitor C1 is connected between drain D and gate G, which is equivalent to being connected in parallel with Miller capacitance (parasitic capacitance between gate G and drain D) of switching transistor Q1 between gate G and drain D, thereby equivalently increasing Miller capacitance and reducing forward voltage V DS The rate of decline slows down the turn-on speed of the switching transistor Q1, which is beneficial to reduce the electromagnetic radiation interference generated at the moment of turn-on. When the switching transistor is turned off, that is, the voltage V from the gate G to the source S GS Switches to a low level, at which time the diode D1 is in a reverse cutoff state, so the capacitor C1 and the resistor R1 are connected in series between the drain D and the gate G. It should be understood that when the switch transistor Q1 is turned on, the capacitor C1 is in a discharge state during the Miller plateau period, and its discharge current flows from the capacitor C1 to the drain D, thereby causing a portion of the input current of the gate G to be diverted, thereby causing the voltage V between the gate G and the source S to be GS Reach saturation. Conversely, when the switch transistor Q1 is turned off, the capacitor C1 is in a charging state and the charging current flows from the drain D to the capacitor C1. At this time, due to the influence of the resistor R1 connected in series with the capacitor C1, the charging process of the capacitor C1 has little effect on the turn-off speed of the switch transistor Q1. In this way, when the switch transistor Q1 is turned on, that is, in the transient state, the forward voltage V from the drain D to the source S is DS The rate of change over time is less than the forward voltage V when the switching transistor Q1 is turned off, that is, in the off transient state. DSThe rate of change over time can reduce the EMI generated when the switch transistor Q1 is turned on while not affecting the turn-off performance. Among them, whether the switch transistor Q1 is in the turn-on transient state or the turn-off state can be determined according to the voltage V from the gate G to the source S GS It can be judged based on the voltage V from the gate G to the drain D GD judge.

[0095] Please continue reading Figure 3 When a surge event occurs, the potential of the drain D of the switching transistor Q1 may increase significantly. At this time, the diode D1 will be in a reverse cut-off state, thereby preventing the high voltage of the drain D of the switching transistor Q1 from being connected to the gate G of the switching transistor Q1 through the capacitor C1 and causing damage to the switching transistor Q1, thereby avoiding adverse effects on the cut-off performance of the transistor.

[0096] Figure 3 The switching transistor Q1 shown is an N-channel enhancement MOSFET. In some exemplary embodiments, the switching transistor Q1 may adopt other types of MOSFETs (such as P-channel enhancement MOSFET or N-channel depletion MOSFET), or may adopt other types of semiconductor switching devices, such as GTR, IGBT, GTO, SCR or other suitable devices, and configure the parasitic body diode accordingly.

[0097] See also Figure 3 In some exemplary embodiments, the diode D1 can be implemented by using appropriate means in the prior art, such as using a point contact type, a surface contact type or a planar type diode. These can be adjusted and improved according to the specific application environment and are not specifically limited here.

[0098] See also Figure 3 In some exemplary embodiments, the capacitor C1 can be implemented by using appropriate means in the prior art. These can be adjusted and improved according to the specific application environment and are not specifically limited here.

[0099] See also Figure 4 , Figure 4 FIG. 2 shows a circuit schematic diagram of a switch circuit according to another implementation method provided in an embodiment of the present application. Figure 4As shown, the switching circuit 400 includes a capacitor C1, a resistor R1, a switch S1, a switching transistor Q1 and a parasitic body diode D0 of the switching transistor Q1. Although the parasitic body diode D0 has a separate reference numeral, it should be regarded as an inherent part of the switching transistor Q1. Among them, the resistor R1 and the switch S1 are connected in parallel between the capacitor C1 and the gate G of the switching transistor Q1. The capacitor C1 is connected to the drain D of the switching transistor Q1. One end of the switch S1 is connected to the gate G of the switching transistor Q1, and the other end is connected to the capacitor C1. The capacitor C1, the resistor R1 and the switch S1 constitute a feedback circuit between the gate G and the drain D of the switching transistor Q1. It should be understood that the switch S1 can be understood as a switch tube S1 or other devices with similar functions.

[0100] Please continue reading Figure 4 The feedback circuit composed of capacitor C1, resistor R1 and switch S1 provides different feedbacks for the switching transistor Q1 in the turn-on transient state when switching from the turn-off state to the turn-on state or the turn-off transient state when switching from the turn-on state to the turn-off state. Specifically, when the switching transistor Q1 is turned on, that is, the voltage V from the gate G to the source S is GS Switch to high level, then switch S1 is in closed state, so R1 connected in parallel with switch S1 is equivalent to being short-circuited. In this way, when the switch transistor Q1 is turned on, capacitor C1 is connected between drain D and gate G, which is equivalent to being connected in parallel with the Miller capacitance (parasitic capacitance between gate G and drain D) of the switch transistor Q1 between gate G and drain D, thereby equivalently increasing the Miller capacitance and reducing the forward voltage V DS The rate of decline slows down the turn-on speed of the switching transistor Q1, which is beneficial to reduce the electromagnetic radiation interference generated at the moment of turn-on. When the switching transistor is turned off, that is, the voltage V from the gate G to the source S GS Switch to low level, at this time, switch S1 is in off state, so capacitor C1 and resistor R1 are connected in series between drain D and gate G. It should be understood that when switch transistor Q1 is turned on, capacitor C1 is in discharge state during Miller plateau period, and its discharge current flows from capacitor C1 to drain D, thereby causing the input current of gate G to be shunted away, thereby causing the voltage V between gate G and source S to be GSReach saturation. Conversely, when the switching transistor Q1 is turned off, the capacitor C1 is in a charging state and the charging current flows from the drain D to the capacitor C1. At this time, due to the influence of the resistor R1 connected in series with the capacitor C1, the charging process of the capacitor C1 has little effect on the turn-off speed of the switching transistor Q1. It should be understood that the switch S1 is closed before the switching transistor Q1 is turned on (switched from the off state to the on state) so that the capacitor C1 is connected between the drain D and the gate G without passing through the resistor R1; the switch S1 is disconnected before the switching transistor Q1 is turned off (switched from the on state to the off state) so that the capacitor C1 and the resistor R1 are connected in series between the drain D and the gate G. In this way, when the switching transistor Q1 is turned on at the moment, that is, in the transient state, the forward voltage V from the drain D to the source S DS The rate of change over time is less than the forward voltage V when the switching transistor Q1 is turned off, that is, in the off transient state. DS The rate of change over time can reduce the EMI generated when the switch transistor Q1 is turned on while not affecting the turn-off performance. Among them, whether the switch transistor Q1 is in the turn-on transient state or the turn-off state can be determined according to the voltage V from the gate G to the source S GS It can be judged based on the voltage V from the gate G to the drain D GD judge.

[0101] Figure 4 The switching transistor Q1 shown is an N-channel enhancement MOSFET. In some exemplary embodiments, the switching transistor Q1 may adopt other types of MOSFETs (such as P-channel enhancement MOSFET or N-channel depletion MOSFET), or may adopt other types of semiconductor switching devices, such as GTR, IGBT, GTO, SCR or other suitable devices, and configure the parasitic body diode accordingly.

[0102] See also Figure 4 In some exemplary embodiments, the switch S1 can be implemented by using appropriate means in the prior art. The switch S1 can be switched between on and off based on the voltage V from the gate G to the source S of the switching transistor Q1. GS To determine, for example, the control signal of switch S1 and the voltage V from gate G to source S GS These can be adjusted and improved according to the specific application environment and are not specifically limited here.

[0103] See also Figure 4 In some exemplary embodiments, the capacitor C1 can be implemented by using appropriate means in the prior art. These can be adjusted and improved according to the specific application environment and are not specifically limited here.

[0104] See also Figure 5 , Figure 5 FIG. 2 shows a circuit schematic diagram of a switch circuit according to another implementation method provided in an embodiment of the present application. Figure 5 As shown, the switching circuit 500 includes a capacitor C1, a resistor R1, a switch S1, a switching transistor Q1 and a parasitic body diode D0 of the switching transistor Q1. Although the parasitic body diode D0 has a separate reference numeral, it should be regarded as an inherent part of the switching transistor Q1. Among them, the resistor R1 and the switch S1 are connected in parallel between the capacitor C1 and the drain D of the switching transistor Q1. The capacitor C1 is connected to the gate G of the switching transistor Q1. One end of the switch S1 is connected to the drain D of the switching transistor Q1, and the other end is connected to the capacitor C1. The capacitor C1, the resistor R1 and the switch S1 constitute a feedback circuit between the gate G and the drain D of the switching transistor Q1. It should be understood that the switch S1 can be understood as a switch tube S1 or other devices with similar functions.

[0105] Please continue reading Figure 5 The feedback circuit composed of capacitor C1, resistor R1 and switch S1 provides different feedbacks for the switching transistor Q1 in the turn-on transient state when switching from the turn-off state to the turn-on state or the turn-off transient state when switching from the turn-on state to the turn-off state. Specifically, when the switching transistor Q1 is turned on, that is, the voltage V from the gate G to the source S is GS Switch to high level, then switch S1 is in closed state, so R1 connected in parallel with switch S1 is equivalent to being short-circuited. In this way, when the switch transistor Q1 is turned on, capacitor C1 is connected between drain D and gate G, which is equivalent to being connected in parallel with the Miller capacitance (parasitic capacitance between gate G and drain D) of the switch transistor Q1 between gate G and drain D, thereby equivalently increasing the Miller capacitance and reducing the forward voltage V DS The rate of decline slows down the turn-on speed of the switching transistor Q1, which is beneficial to reduce the electromagnetic radiation interference generated at the moment of turn-on. When the switching transistor is turned off, that is, the voltage V from the gate G to the source S GS Switch to low level, at this time, switch S1 is in off state, so capacitor C1 and resistor R1 are connected in series between drain D and gate G. It should be understood that when switch transistor Q1 is turned on, capacitor C1 is in discharge state during Miller plateau period, and its discharge current flows from capacitor C1 to drain D, thereby causing the input current of gate G to be shunted away, thereby causing the voltage V between gate G and source S to be GSReach saturation. Conversely, when the switching transistor Q1 is turned off, the capacitor C1 is in a charging state and the charging current flows from the drain D to the capacitor C1. At this time, due to the influence of the resistor R1 connected in series with the capacitor C1, the charging process of the capacitor C1 has little effect on the turn-off speed of the switching transistor Q1. It should be understood that the switch S1 is closed before the switching transistor Q1 is turned on (switched from the off state to the on state) so that the capacitor C1 is connected between the drain D and the gate G without passing through the resistor R1; the switch S1 is disconnected before the switching transistor Q1 is turned off (switched from the on state to the off state) so that the capacitor C1 and the resistor R1 are connected in series between the drain D and the gate G. In this way, when the switching transistor Q1 is turned on at the moment, that is, in the transient state, the forward voltage V from the drain D to the source S DS The rate of change over time is less than the forward voltage V when the switching transistor Q1 is turned off, that is, in the off transient state. DS The rate of change over time can reduce the EMI generated when the switch transistor Q1 is turned on while not affecting the turn-off performance. Among them, whether the switch transistor Q1 is in the turn-on transient state or the turn-off state can be determined according to the voltage V from the gate G to the source S GS It can be judged based on the voltage V from the gate G to the drain D GD judge.

[0106] Figure 5 The switching transistor Q1 shown is an N-channel enhancement MOSFET. In some exemplary embodiments, the switching transistor Q1 may adopt other types of MOSFETs (such as P-channel enhancement MOSFET or N-channel depletion MOSFET), or may adopt other types of semiconductor switching devices, such as GTR, IGBT, GTO, SCR or other suitable devices, and configure the parasitic body diode accordingly.

[0107] See also Figure 5 In some exemplary embodiments, the switch S1 can be implemented by using appropriate means in the prior art. The switch S1 can be switched between on and off based on the voltage V from the gate G to the source S of the switching transistor Q1. GS To determine, for example, the control signal of switch S1 and the voltage V from gate G to source S GS These can be adjusted and improved according to the specific application environment and are not specifically limited here.

[0108] See also Figure 5 In some exemplary embodiments, the capacitor C1 can be implemented by using appropriate means in the prior art. These can be adjusted and improved according to the specific application environment and are not specifically limited here.

[0109] See also Figure 6 , Figure 6 FIG. 2 shows a circuit schematic diagram of a switch circuit according to another implementation method provided in an embodiment of the present application. Figure 6 As shown, the switch circuit 600 includes a switch transistor Q1 and its body diode D0, a first capacitor C1, a second capacitor C2, a third capacitor C3, a resistor R1 and a diode D1. The switch transistor Q1 includes a control electrode G, a first transmission electrode S and a second transmission electrode D. The switch transistor Q1 controls the switch transistor to be turned on or off by controlling the voltage from the control electrode G to the first transmission electrode S. One end of each of the first capacitor C1, the second capacitor C2 and the third capacitor C3 is connected to each other. The resistor R1 and the diode D1 are connected in parallel between the other end of the first capacitor C1 and the control electrode G. The other end of the second capacitor C2 is connected to the second transmission electrode D, and the other end of the third capacitor C3 is connected to the first transmission electrode S. When the voltage from the control electrode G to the first transmission electrode S is greater than the threshold voltage, the diode D1 is forwardly conducted so that the first capacitor C1 and the second capacitor C2 are connected in series between the control electrode G and the second transmission electrode D without passing through the resistor R1. When the voltage from the control electrode G to the first transmission electrode S is less than the threshold voltage, the diode D1 is reversely cut off so that the first capacitor C1, the second capacitor C2 and the resistor R1 are connected in series between the control electrode G and the second transmission electrode D. When the switch transistor Q1 is turned on, the first capacitor C1 and the second capacitor C2 are connected in series and then connected in parallel with the parasitic capacitance between the control electrode G and the second transmission electrode D between the control electrode G and the second transmission electrode D, which is equivalent to increasing the parasitic capacitance, that is, the Miller capacitance, thereby extending the Miller platform time and reducing the forward voltage V from the second transmission electrode D to the first transmission electrode S. DSWhen the switch transistor Q1 is turned off, the diode D1 is in a reverse cut-off state, and the first capacitor C1, the second capacitor C2, the third capacitor C3 and the resistor R1 form a charging circuit between the control electrode G and the second transmission electrode D. At this time, due to the influence of the resistor R1, the capacitor charging process has a small impact on the turn-off speed of the switch transistor Q1. It should be understood that when the voltage from the control electrode G to the first transmission electrode S is greater than the threshold voltage, the switch transistor Q1 is turned on so that the voltage of the second transmission electrode D decreases, thereby causing the diode D1 to be forward-conducted, so that the first capacitor C1 and the second capacitor C2 are connected in series between the control electrode G and the second transmission electrode D without passing through the resistor R1. When the voltage from the control electrode G to the first transmission electrode S is less than the threshold voltage, the switch transistor Q1 is turned off so that the voltage of the second transmission electrode D increases, thereby causing the diode D1 to be reverse cut-off, so that the first capacitor C1, the second capacitor C2 and the resistor R1 are connected in series between the control electrode G and the second transmission electrode D. Thus, when the switch transistor Q1 is turned on at the moment of being turned on, that is, in the transient state, the forward voltage V from the second transmission electrode D to the first transmission electrode S is DS The rate of change over time is less than the forward voltage V when the switching transistor Q1 is turned off, that is, in the off transient state. DS The rate of change over time can reduce the EMI generated when the switch transistor Q1 is turned on while not affecting the turn-off performance. The switch transistor Q1 is in the on-state or off-state according to the voltage V from the control electrode G to the first transmission electrode S. GS It can be determined based on the voltage V from the control electrode G to the second transmission electrode D. GD It should be understood that in another possible implementation, the resistor R1 and the diode D1 can be connected in parallel with the first capacitor C1. Figure 6 The positions shown in are interchanged with each other. That is, the second capacitor C2 and the third capacitor C3 each have one end connected to each other; one end of the first capacitor C1 is connected to the control electrode G of the switch transistor Q1; the resistor R1 and the diode D1 are connected in parallel to the other end of the first capacitor C1 and are connected between the second capacitor C2 and the third capacitor C3.

[0110] Please continue reading Figure 6, when a surge event occurs, the potential of the second transmission electrode D of the switching transistor Q1 may increase significantly, and at this time the diode D1 will be in a reverse cut-off state, thereby preventing the high voltage of the second transmission electrode D of the switching transistor Q1 from being connected in series with the control electrode G of the switching transistor Q1 through the capacitors C1 and C2, thereby preventing the switching transistor Q1 from being damaged, thereby avoiding adverse effects on the cut-off performance of the transistor. In other words, the diode D1 is configured to block the surge voltage of the second transmission electrode D relative to the first transmission electrode S, thereby providing surge blocking protection for the switching transistor Q1. When the second transmission electrode D is at a high voltage potential, the diode D1 must be guaranteed not to be reversely broken down, so it needs to be designed to withstand high voltage. The second capacitor C2 and the third capacitor C3 form a voltage divider circuit between the second transmission electrode D and the first transmission electrode S, thereby reducing the feedback voltage drop on the diode D1, and a low-voltage device can be selected as the diode D1.

[0111] Please participate Figures 2 to 6 , an embodiment of the present application provides a switch circuit that affects the Miller platform based on voltage feedback to improve the switch interference performance of the switch transistor. The switch circuit includes: a switch transistor, wherein the switch transistor includes a control electrode, a first transmission electrode and a second transmission electrode, and the switch transistor controls the switch transistor to switch between an on state and an off state by controlling the voltage from the control electrode to the first transmission electrode; and a feedback circuit, wherein the feedback circuit is connected between the control electrode and the second transmission electrode, and the feedback circuit is configured to provide a first voltage feedback when the switch transistor switches from the off state to the on state, and the feedback circuit is configured to provide a second voltage feedback when the switch transistor switches from the on state to the off state. Wherein, when the switch transistor switches from the off state to the on state, the Miller platform of the switch transistor, under the action of the first voltage feedback, causes the forward voltage from the second transmission electrode to the first transmission electrode to change at a first rate over time. When the switch transistor switches from the on state to the off state, the Miller platform of the switch transistor causes the forward voltage from the second transmission electrode to the first transmission electrode to change at a second rate over time under the action of the second voltage feedback.

[0112] See also Figure 7 , Figure 7 FIG. 2 shows a circuit schematic diagram of a switch circuit according to another implementation method provided in an embodiment of the present application. Figure 7As shown, the switch circuit 700 includes a switch transistor Q1. The switch transistor Q1 includes a control electrode G, a first transmission electrode S and a second transmission electrode D. The switch transistor Q1 controls the switch transistor Q1 to turn on or off by controlling the voltage from the control electrode G to the first transmission electrode S. The switch circuit 700 also includes a first capacitor C1, a second capacitor C2, and a third capacitor C3. The first capacitor C1, the second capacitor C2 and the third capacitor C3 each have one end connected to each other. The switch circuit 700 also includes a resistor R1. One end of the resistor R1 is connected to the control electrode G, and the other end of the resistor R1 is connected to the other end of the first capacitor C1. The switch circuit 700 also includes a diode D1. The cathode of the diode D1 is connected to the other end of the first capacitor C1, and the anode of the diode D1 is connected to the base of the PNP transistor Q2. The other end of the second capacitor C2 is connected to the second transmission electrode D, and the other end of the third capacitor C3 is connected to the first transmission electrode S. The emitter of the PNP transistor is connected to the control electrode G, and the collector of the PNP transistor is connected to the first transmission electrode S. When the voltage from the control electrode G to the first transmission electrode S is greater than the threshold voltage, the diode D1 is forwardly conducted so that the first capacitor C1 and the second capacitor C2 are connected in series between the base of the PNP transistor and the second transmission electrode D without passing through the resistor R1, and the discharge current flowing through the first capacitor C1 is amplified by the PNP transistor to enhance the feedback of the input current of the control electrode G. Therefore, when the switching transistor Q1 is turned on, the first capacitor C1 and the second capacitor C2 are in a discharge state, and the discharge current flowing through the first capacitor C1 is amplified by the PNP transistor and then fed back to the input current of the control electrode G, thereby reducing the EMI generated when the switching transistor Q1 is turned on and improving the switching interference. When the voltage from the control electrode G to the first transmission electrode S is less than the threshold voltage, the diode D1 is reversely cut off so that the first capacitor C1, the second capacitor C2 and the resistor R1 are connected in series between the control electrode G and the second transmission electrode D. At this time, due to the influence of the resistor R1, the capacitor charging process has little effect on the turn-off speed of the switching transistor Q1. In this way, when the switching transistor Q1 is turned on, that is, in the transient state, the forward voltage V from the second transmission electrode D to the first transmission electrode S is DS The rate of change over time is less than the forward voltage V when the switching transistor Q1 is turned off, that is, in the off transient state. DSThe rate of change over time can reduce the EMI generated when the switch transistor Q1 is turned on while not affecting the turn-off performance. The switch transistor Q1 is in the on-state or off-state according to the voltage V from the control electrode G to the first transmission electrode S. GS It can be determined based on the voltage V from the control electrode G to the second transmission electrode D. GD judge.

[0113] In some exemplary embodiments, Figure 7 The PNP transistor shown can be replaced by other devices having a signal amplification function, such as a current signal amplifier, an operational amplifier or other types of transistors.

[0114] See also Figure 8 , Figure 8 FIG. 2 shows a circuit schematic diagram of a switch circuit according to another implementation method provided in an embodiment of the present application. Figure 8 As shown, the switch circuit 800 includes a switch transistor Q1. The switch transistor Q1 includes a control electrode G, a first transmission electrode S, and a second transmission electrode D. The switch transistor Q1 controls the forward current I flowing from the second transmission electrode D to the first transmission electrode S by controlling the voltage from the control electrode G to the first transmission electrode S. DS The switch circuit 800 further includes a sampling resistor R1. One end of the sampling resistor R1 is connected to the first transmission electrode S, and the other end of the sampling resistor is grounded GND. The voltage change of the sampling resistor R1 corresponds to the forward current I DS The switch circuit 800 further includes an amplifier U1. The input end of the amplifier U1 is connected to both ends of the sampling resistor R1, and the output end of the amplifier U1 is coupled to the base of the NPN transistor Q2. The emitter of the NPN transistor is grounded GND, and the collector of the NPN transistor is connected to the control electrode G. The forward current I flowing from the second transmission electrode D to the first transmission electrode S DS The change of is amplified by the amplifier U1 to enhance the feedback of the input current of the control electrode G. The switch circuit 800 may also include a capacitor C1, which is connected in series between the output end of the amplifier U1 and the base of the NPN transistor Q2. The switch circuit 800 may also include a resistor R2, one end of the resistor R2 is grounded and the other end is connected to the base of the NPN transistor Q2. In this way, the forward current I can be sampled through the sampling resistor R1. DS The change with time, and this change is amplified by amplifier U1 and fed back to the input current of control electrode G. DSWhen the change over time is fast, that is, the switch transistor Q1 may generate large EMI due to the drastic change of current, at this time, the forward current I can be suppressed by the feedback loop design of the switch circuit 800. DS The change over time reduces the EMI generated by the switching transistor Q1 during high-speed switching.

[0115] In some exemplary embodiments, Figure 8 The NPN transistor shown can be replaced by other devices having a signal amplification function, such as a current signal amplifier, an operational amplifier or other types of transistors.

[0116] See also Figure 7 and Figure 8 , an embodiment of the present application provides a switch circuit that affects the Miller platform based on current feedback to improve the switch interference performance of the switch transistor. The switch circuit includes: a switch transistor, wherein the switch transistor includes a control electrode, a first transmission electrode and a second transmission electrode, and the switch transistor controls the switch transistor to switch between an on state and an off state by controlling the voltage or current from the control electrode to the first transmission electrode; and a feedback circuit, wherein the feedback circuit is connected between the control electrode and the first transmission electrode, and the feedback circuit is configured to provide a first current feedback when the switch transistor switches from the off state to the on state, and the feedback circuit is configured to provide a second current feedback when the switch transistor switches from the on state to the off state. Wherein, when the switch transistor switches from the off state to the on state, the Miller platform of the switch transistor, under the action of the first current feedback, causes the forward current from the second transmission electrode to the first transmission electrode to change at a first rate over time. When the switch transistor switches from the on state to the off state, the Miller platform of the switch transistor causes the forward current from the second transmission electrode to the first transmission electrode to change at a second rate over time under the action of the second current feedback.

[0117] The specific embodiments provided by the present application can be implemented with any one or combination of hardware, software, firmware or solid-state logic circuits, and can be implemented in combination with signal processing, control and / or special circuits. The equipment or device provided by the specific embodiments of the present application may include one or more processors (e.g., microprocessors, controllers, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), etc.), which process various computer-executable instructions to control the operation of the equipment or device. The equipment or device provided by the specific embodiments of the present application may include a system bus or a data transmission system that couples various components together. The system bus may include any one or a combination of different bus structures, such as a memory bus or a memory controller, a peripheral bus, a universal serial bus and / or a processor or local bus utilizing any one of a variety of bus architectures. The equipment or device provided by the specific embodiments of the present application may be provided separately, may be a part of a system, or may be a part of other equipment or devices.

[0118] The specific embodiments provided in this application may include a computer-readable storage medium or be combined with a computer-readable storage medium, such as one or more storage devices capable of providing non-temporary data storage. The computer-readable storage medium / storage device may be configured to store data, programmers and / or instructions, which, when executed by a processor of a device or apparatus provided in a specific embodiment of this application, enable these devices or apparatuses to perform related operations. The computer-readable storage medium / storage device may include one or more of the following features: volatility, non-volatility, dynamic, static, readable / writable, read-only, random access, sequential access, location addressability, file addressability, and content addressability. In one or more exemplary embodiments, the computer-readable storage medium / storage device may be integrated into the device or apparatus provided in a specific embodiment of this application or belong to a common system. Computer-readable storage media / storage devices may include optical storage devices, semiconductor storage devices and / or magnetic storage devices, etc., and may also include random access memory (RAM), flash memory, read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, removable disks, recordable and / or rewritable compact disks (CDs), digital versatile disks (DVDs), mass storage media devices or any other form of suitable storage media.

[0119] The above is the implementation method of the embodiment of the present application. It should be noted that the steps in the method described in the specific embodiment of the present application can be adjusted in order, merged and deleted according to actual needs. In the above embodiments, the description of each embodiment has its own emphasis. For the part that is not described in detail in a certain embodiment, refer to the relevant description of other embodiments. It is understandable that the structure shown in the embodiment of the present application and the accompanying drawings does not constitute a specific limitation on the relevant device or system. In other embodiments of the present application, the relevant device or system may include more or fewer components than the specific embodiments and the accompanying drawings, or combine certain components, or split certain components, or have different component arrangements. Those skilled in the art will understand that, without departing from the spirit and scope of the specific embodiments of the present application, various modifications or changes can be made to the arrangement, operation and details of the methods and equipment recorded in the specific embodiments; without departing from the principles of the embodiments of the present application, several improvements and modifications can also be made, and these improvements and modifications are also regarded as the scope of protection of the present application.

Claims

1. A switching circuit, characterized in that: The switch circuit comprises: A switching transistor, wherein the switching transistor comprises a control electrode, a first transmission electrode and a second transmission electrode, and the switching transistor is controlled to switch between an on state and an off state by controlling a voltage or a current from the control electrode to the first transmission electrode; and a feedback circuit, wherein the feedback circuit is connected between the control electrode and the first transmission electrode, or the feedback circuit is connected between the control electrode and the second transmission electrode, the feedback circuit is configured to provide a first feedback when the switching transistor is switched from the off state to the on state, and the feedback circuit is configured to provide a second feedback when the switching transistor is switched from the on state to the off state, wherein the rate of change over time of the forward voltage or the forward current from the second transmission electrode to the first transmission electrode is adjusted according to the feedback circuit; The switching transistor is controlled to switch between an on state and an off state by controlling the voltage from the control electrode to the first transmission electrode, the first feedback and the second feedback are both voltage feedback, the feedback circuit is connected between the control electrode and the second transmission electrode, when the switching transistor is switched from the off state to the on state, the rate of change of the forward voltage of the switching transistor under the action of the first feedback over time is a first rate, and when the switching transistor is switched from the on state to the off state, the rate of change of the forward voltage of the switching transistor under the action of the second feedback over time is a second rate.

2. The switch circuit according to claim 1, characterized in that: The feedback circuit comprises: capacitance, resistor, and diode, wherein the resistor and the diode are connected in parallel between the capacitor and the switching transistor, When the switch transistor switches from the off state to the on state, the diode is configured to be forward-conducted so that the capacitor is connected between the control electrode and the second transmission electrode without passing through the resistor. When the switch transistor is switched from the on state to the off state, the diode is configured to be reversely cut off so that the capacitor and the resistor are connected in series between the control electrode and the second transmission electrode.

3. The switch circuit according to claim 1, characterized in that: The feedback circuit comprises: capacitance, resistor, and switch, wherein the resistor and the switch are connected in parallel between the capacitor and the switch transistor, The switch is closed before the switch transistor switches from the off state to the on state so that the capacitor is connected between the control electrode and the second transmission electrode without passing through the resistor. The switch is disconnected before the switch transistor switches from the on state to the off state so that the capacitor and the resistor are connected in series between the control electrode and the second transmission electrode.

4. The switch circuit according to claim 1, characterized in that: The feedback circuit comprises: A first capacitor, a second capacitor, and a third capacitor, wherein one end of each of the first capacitor, the second capacitor, and the third capacitor is connected to each other; resistor; and a diode, wherein the resistor and the diode are connected in parallel between the other end of the first capacitor and the control electrode; The other end of the second capacitor is connected to the second transmission electrode, and the other end of the third capacitor is connected to the first transmission electrode. When the voltage from the control electrode to the first transmission electrode is greater than a threshold voltage, the switch transistor is turned on so that the voltage of the second transmission electrode drops, thereby causing the diode to conduct forward, so that the first capacitor and the second capacitor are connected in series between the control electrode and the second transmission electrode without passing through the resistor. When the voltage from the control electrode to the first transmission electrode is less than the threshold voltage, the switching transistor is turned off so that the voltage of the second transmission electrode rises, thereby causing the diode to be reversely turned off, so that the first capacitor, the second capacitor and the resistor are connected in series between the control electrode and the second transmission electrode.

5. The switch circuit according to claim 1, characterized in that: The feedback circuit comprises: A first capacitor, a second capacitor, and a third capacitor, wherein one end of each of the second capacitor and the third capacitor is connected to each other, and one end of the first capacitor is connected to the control electrode of the switch transistor; resistor; and A diode, wherein the resistor and the diode are connected in parallel to the other end of the first capacitor and are connected between the second capacitor and the third capacitor; The other end of the second capacitor is connected to the second transmission electrode, and the other end of the third capacitor is connected to the first transmission electrode. When the voltage from the control electrode to the first transmission electrode is greater than a threshold voltage, the switch transistor is turned on so that the voltage of the second transmission electrode drops, thereby causing the diode to conduct forward, so that the first capacitor and the second capacitor are connected in series between the control electrode and the second transmission electrode without passing through the resistor. When the voltage from the control electrode to the first transmission electrode is less than the threshold voltage, the switching transistor is turned off so that the voltage of the second transmission electrode rises, thereby causing the diode to be reversely turned off, so that the first capacitor, the second capacitor and the resistor are connected in series between the control electrode and the second transmission electrode.

6. The switch circuit according to claim 2 or 3, characterized in that: When the switch transistor switches from the off state to the on state, the capacitor is connected in parallel with the Miller capacitance of the switch transistor between the control electrode and the second transmission electrode, thereby reducing the rate of change of the forward voltage over time.

7. The switch circuit according to claim 2 or 3, characterized in that: When the switch transistor switches from the on state to the off state, the capacitor and the resistor form a charging loop between the control electrode and the second transmission electrode.

8. The switch circuit according to claim 4 or 5, characterized in that: When the switching transistor switches from the off state to the on state, the first capacitor and the second capacitor are connected in series and then connected in parallel with the parasitic capacitance between the control electrode and the second transmission electrode between the control electrode and the second transmission electrode, thereby reducing the rate of change of the forward voltage over time.

9. The switch circuit according to claim 4 or 5, characterized in that: When the switch transistor switches from the on state to the off state, the first capacitor, the second capacitor, the third capacitor and the resistor form a charging loop between the control electrode and the second transmission electrode.

10. The switch circuit according to any one of claims 2, 4 and 5, characterized in that: The diode is configured to block a surge voltage of the second transmission electrode relative to the control electrode to provide surge blocking protection for the switching transistor.

11. The switch circuit according to claim 2, characterized in that: An anode of the diode is connected to the control electrode, a cathode of the diode is connected to one end of the capacitor, and the other end of the capacitor is connected to the control electrode.

12. The switch circuit according to claim 2, characterized in that: The cathode of the diode is connected to the control electrode, the anode of the diode is connected to one end of the capacitor, and the other end of the capacitor is connected to the control electrode.

13. The switch circuit according to claim 4 or 5, characterized in that: The second capacitor and the third capacitor form a voltage dividing loop between the second transmission electrode and the first transmission electrode.

14. The switch circuit according to claim 1, characterized in that: The switching transistor controls the switching between an on state and an off state by controlling the current from the control electrode to the first transmission electrode. The first feedback and the second feedback are both current feedback. The feedback circuit is connected between the control electrode and the first transmission electrode. When the switching transistor switches from the off state to the on state, the rate of change of the forward current of the switching transistor under the action of the first feedback over time is a third rate. When the switching transistor switches from the on state to the off state, the rate of change of the forward current of the switching transistor under the action of the second feedback over time is a fourth rate.

15. The switch circuit according to claim 14, characterized in that: The feedback circuit comprises: A first capacitor, a second capacitor, and a third capacitor, wherein one end of each of the first capacitor, the second capacitor, and the third capacitor is connected to each other; a resistor, wherein one end of the resistor is connected to the control electrode, and the other end of the resistor is connected to the other end of the first capacitor; and A diode, wherein a cathode of the diode is connected to the other end of the first capacitor, and an anode of the diode is connected to the base of the current signal amplifier; The other end of the second capacitor is connected to the second transmission electrode, and the other end of the third capacitor is connected to the first transmission electrode. The emitter of the current signal amplifier is connected to the control electrode, and the collector of the current signal amplifier is connected to the first transmission electrode. Wherein, when the voltage from the control electrode to the first transmission electrode is greater than the threshold voltage, the diode is forwardly conducted so that the first capacitor and the second capacitor are connected in series between the base of the current signal amplifier and the second transmission electrode without passing through the resistor, and the discharge current flowing through the first capacitor is amplified by the current signal amplifier to enhance the feedback of the input current to the control electrode; When the voltage from the control electrode to the first transmission electrode is less than the threshold voltage, the diode is reversely cut off so that the first capacitor, the second capacitor and the resistor are connected in series between the control electrode and the second transmission electrode.

16. The switch circuit according to claim 14, characterized in that: The feedback circuit comprises: a sampling resistor, wherein one end of the sampling resistor is connected to the first transmission electrode, the other end of the sampling resistor is grounded, and a voltage change of the sampling resistor corresponds to a change of the forward current; and An amplifier, wherein the input end of the amplifier is connected to both ends of the sampling resistor, the output end of the amplifier is coupled to the base of the current signal amplifier, the emitter of the current signal amplifier is grounded, and the collector of the current signal amplifier is connected to the control electrode. The change of the forward current flowing from the second transmission electrode to the first transmission electrode is amplified by the amplifier to enhance the feedback of the input current to the control electrode.

17. The switch circuit according to claim 15 or 16, characterized in that: The current signal amplifier is a triode.

18. The switch circuit according to claim 17, characterized in that: The switch transistor is a metal oxide semiconductor field effect transistor MOSFET, and the control electrode, the first transmission electrode and the second transmission electrode of the switch transistor correspond to the gate, source and drain of the MOSFET respectively.

19. The switch circuit according to claim 17, characterized in that: The switching transistor is an insulated gate bipolar transistor (IGBT), and the control electrode, the first transmission electrode and the second transmission electrode of the switching transistor correspond to the control electrode, the emitter electrode and the collector electrode of the IGBT respectively.

20. The switch circuit according to claim 17, characterized in that: The switch transistor is a high electron mobility transistor (HEMT), and the control electrode, the first transmission electrode and the second transmission electrode of the switch transistor correspond to the gate, the source and the drain of the HEMT respectively.

21. The switch circuit according to claim 20, characterized in that: The HEMT is a gallium nitride GaN HEMT.

22. The switch circuit according to claim 17, characterized in that: The switching transistor is a silicon controlled rectifier (SCR), and the control electrode, the first transmission electrode and the second transmission electrode of the switching transistor correspond to the control electrode, the anode and the cathode of the SCR respectively.

23. A photovoltaic power supply system, characterized in that: The photovoltaic power supply system comprises a switching circuit according to any one of claims 1-22.

24. An uninterruptible power supply UPS, characterized in that: The uninterruptible power supply comprises a switching circuit according to any one of claims 1-22.

25. An inverter, characterized in that: The inverter comprises a switching circuit according to any one of claims 1-22.

26. A frequency converter, characterized in that: The frequency converter comprises a switching circuit according to any one of claims 1-22.

27. A vehicle-mounted power supply device, characterized in that: The on-vehicle power supply device comprises a switch circuit according to any one of claims 1-22.

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