Switching tube control circuit, bridgeless circuit and control method thereof

Abstract

The invention discloses a switching tube control circuit, a bridgeless circuit and a control method thereof. The switching tube control circuit comprises a detection module, a control module and an impedance configuration module. The detection module outputs a detection signal based on the voltage of the AC power supply. The control module outputs a surge protection signal and outputs a control signal when determining that the AC power supply surges based on the detection signal. The impedance configuration module comprises a turn-off branch circuit, the impedance of the turn-off branch circuit is configured to be first turn-off impedance when the turn-off branch circuit operates and does not receive the surge protection signal, and the impedance of the turn-off branch circuit is configured to be second turn-off impedance in response to the surge protection signal when the turn-off branch circuit operates and receives the surge protection signal, the first turn-off impedance is smaller than the second turn-off impedance, and the turn-off branch runs when the control signal is used for controlling the switch tube to be turned off. Through the above mode, the risk that the switch tube is damaged when the surge occurs can be reduced.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of switch control, and particularly to a switch control circuit, a bridgeless circuit and a control method thereof. Background Art

[0002] In an energy conversion system, the conversion efficiency of a power supply is very important. Compared with a traditional power conversion circuit, a bridgeless circuit (such as a Totem-Pole Bridgeless circuit) can eliminate some or all of the diodes, reduce the conduction loss of the circuit, and has an advantage in high-efficiency energy conversion.

[0003] A bridgeless circuit usually includes arms implemented by switches. Among them, the arms include a slow arm and a fast arm. Currently, when a surge occurs in an AC power supply, the switches in the slow arm are easily damaged. Summary of the Invention

[0004] The embodiments of the present application provide a switch control circuit, a bridgeless circuit and a control method thereof, which can reduce the risk of damage to the switch when a surge occurs.

[0005] In a first aspect, the embodiments of the present application provide a switch control circuit, including: a detection module, connected to an AC power supply, for outputting a detection signal based on the voltage of the AC power supply; a control module, connected to the detection module, for outputting a surge protection signal and a control signal when it is determined based on the detection signal that a surge occurs in the AC power supply; an impedance configuration module, connected between the control module and the control end of the switch, including a turn-off branch, where the turn-off branch is used to configure the impedance of the turn-off branch to a first turn-off impedance when it operates and does not receive the surge protection signal, and is used to configure the impedance of the turn-off branch to a second turn-off impedance in response to the surge protection signal when it operates and receives the surge protection signal, where the first turn-off impedance is less than the second turn-off impedance, and the turn-off branch operates when the control signal is used to control the switch to turn off.

[0006] In one or more embodiments, the turn-off branch includes a first resistor, a second resistor, and a first controllable switch; and one of the following two modes is executed: Mode A: The combination of the second resistor and the first controllable switch in series is connected in parallel with the first resistor; when the turn-off branch is operating and does not receive the surge protection signal, the first controllable switch is configured to be closed so that the total impedance of the first resistor and the second resistor in parallel is the first turn-off impedance; when the turn-off branch is operating and receives the surge protection signal, the first controllable switch disconnects in response to the surge protection signal so that the impedance of the first resistor is the second turn-off impedance; Mode B: The combination of the second resistor and the first controllable switch in parallel is connected in series with the first resistor; when the turn-off branch is operating and does not receive the surge protection signal, the first controllable switch is configured to be closed so that the impedance of the second resistor is the first turn-off impedance; when the turn-off branch is operating and receives the surge protection signal, the first controllable switch disconnects in response to the surge protection signal so that the sum of the impedances of the first resistor and the second resistor is the second turn-off impedance.

[0007] In one or more embodiments, the first controllable switch includes a third resistor, a fourth resistor, an NMOS transistor, and a PMOS transistor; the third resistor is connected between the gate and the source of the NMOS transistor, the gate and the source of the NMOS transistor are both connected to the control module, and the drain of the NMOS transistor is connected to the gate of the PMOS transistor. Wherein, when Mode A is executed, the PMOS transistor is also connected in series with the second resistor, and when Mode B is executed, the PMOS transistor is also connected in parallel with the second resistor.

[0008] In one or more embodiments, the turn-off branch further includes a first diode; the anode of the first diode is connected to the control end of the switching transistor, and the combination of the first resistor, the second resistor, and the first controllable switch is connected to the cathode of the first diode.

[0009] In one or more embodiments, the turn-off branch further includes a first triode; the base of the first triode is connected to the control module, the combination of the first resistor, the second resistor, and the first controllable switch is connected to the emitter of the first triode, and the collector of the first triode is connected to the control end of the switching transistor.

[0010] In one or more embodiments, the impedance configuration module further includes a turn-on branch, and the turn-on branch is configured to have a turn-on impedance when it is operating, wherein the turn-on branch operates when the control signal is used to control the switching transistor to turn on.

[0011] In one or more embodiments, the turn-on branch includes a fifth resistor; the turn-on branch further includes a second diode, the fifth resistor is connected between the control module and the anode of the second diode, and the cathode of the second diode is connected to the control end of the switching tube. Alternatively, the turn-on branch further includes a second triode, the fifth resistor is connected between the control module and the emitter of the second triode, the base of the second triode is connected to the control module, and the collector of the second triode is connected to the control end of the switching tube.

[0012] In a second aspect, an embodiment of the present application provides a bridge-less circuit, including a first switching tube, a second switching tube, a detection module and a control module in the switching tube control circuit as described above, and impedance configuration modules in two of the switching tube control circuits; the control module is configured to output a first control signal and a second control signal; the first impedance configuration module is connected between one end where the control module outputs the first control signal and the control end of the first switching tube, and the second impedance configuration module is connected between one end where the control module outputs the second control signal and the control end of the second switching tube, and the first switching tube and the second switching tube are connected in series.

[0013] In one or more embodiments, the control module includes a digital isolator, a controller and a gate driver, and the detection module includes a sixth resistor, a seventh resistor, an eighth resistor and a ninth resistor; the sixth resistor and the seventh resistor are connected in series between the first terminal of the AC power supply and the ground, and the connection point between the sixth resistor and the seventh resistor is connected to the controller; the eighth resistor and the ninth resistor are connected in series between the second terminal of the AC power supply and the ground, and the connection point between the eighth resistor and the ninth resistor is connected to the controller; the controller is respectively connected to the digital isolator, the gate driver and the second impedance configuration module, the digital isolator is connected to the first impedance configuration module, and the gate driver is respectively connected to the first impedance configuration module and the second impedance configuration module.

[0014] In a third aspect, an embodiment of the present application provides a control method based on the bridge-less circuit as described above, including: when it is determined based on the detection signal output by the detection module that the AC power supply is in the positive half cycle and a surge occurs in the AC power supply, controlling the first controllable switch in the second impedance configuration module to turn off, and controlling the second switching tube to turn off; when it is determined based on the detection signal output by the detection module that the AC power supply is in the negative half cycle and a surge occurs in the AC power supply, controlling the first controllable switch in the first impedance configuration module to turn off, and controlling the first switching tube to turn off.

[0015] The beneficial effects of the present application are as follows: The switch control circuit of the embodiment of the present application includes a detection module, a control module, and an impedance configuration module. The detection module is connected to the AC power supply, and the detection module is used to output a detection signal based on the voltage of the AC power supply. The control module is connected to the detection module, and the control module is used to output a surge protection signal and a control signal when it is determined based on the detection signal that a surge occurs in the AC power supply. The impedance configuration module is connected between the control module and the control terminal of the switch tube. The impedance configuration module includes a turn-off branch. The turn-off branch is used to configure the impedance of the turn-off branch to a first turn-off impedance when it operates and does not receive the surge protection signal, and is used to configure its impedance to a second turn-off impedance in response to the surge protection signal when it operates and receives the surge protection signal. Among them, the first turn-off impedance is less than the second turn-off impedance, and the turn-off branch operates when the control signal is used to control the switch tube to turn off. It can be seen that when a surge occurs in the AC power supply, the impedance of the turn-off branch increases from the first turn-off impedance to the second turn-off impedance, so as to effectively reduce the turn-off rate of the switch tube, thereby reducing the risk of damage to the switch tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements.

[0017] Figure 1 is a schematic circuit diagram of a totem-pole bridgeless circuit in the related art;

[0018] Figure 2 is a schematic diagram of the switch control circuit provided by the embodiment of the present application Figure 1 ;

[0019] Figure 3 is a schematic diagram of the switch control circuit provided by the embodiment of the present application Figure 2 ;

[0020] Figure 4 is a schematic diagram of the switch control circuit provided by the embodiment of the present application Figure 3 ;

[0021] Figure 5 is a schematic diagram of the switch control circuit provided by the embodiment of the present application Figure 4 ;

[0022] Figure 6 is a schematic diagram of the switch control circuit provided by the embodiment of the present application Figure 5 ;

[0023] Figure 7 is a schematic diagram of the switch control circuit provided by the embodiment of the present application Figure 6 ;

[0024] Figure 8 is a schematic diagram of a bridge - less circuit provided by an embodiment of the present application Figure 1 ;

[0025] Figure 9 is a schematic diagram of a bridge - less circuit provided by an embodiment of the present application Figure 2 ;

[0026] Figure 10 is a flowchart of a control method for a bridge - less circuit provided by an embodiment of the present application;

[0027] Figure 11 is provided by an embodiment of the present application Figure 9 schematic diagram of some signals in the circuit structure shown. Detailed implementation manners

[0028] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and detailedly described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0029] It should be noted that when an element is expressed as "connected" to another element, it can be directly connected to the other element, or there can be one or more intermediate elements therebetween.

[0030] In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as there is no conflict between them.

[0031] Please refer to Figure 1 , Figure 1 which exemplarily shows a schematic diagram of the circuit structure of a bridge - less circuit in the related art. This bridge - less circuit takes the totem - pole bridge - less circuit as an example. As Figure 1 shown, the totem - pole bridge - less circuit includes an EMI (Electromagnetic Interference) filter U1, diodes DA1, DA2, a first switching transistor S1, a second switching transistor S2, a third switching transistor QA1, a fourth switching transistor QA2, an inductor LA1, a filter capacitor CL, and a load resistor RL (used to represent the load). The first switching transistor S1 and the second switching transistor S2 form a slow bridge arm, and the third switching transistor QA1 and the fourth switching transistor QA2 form a fast bridge arm.

[0032] The input end of the EMI filter U1 is connected to the AC power supply AC. The first end of the output end of the EMI filter U1 is respectively connected to the anode of the diode DA1, the cathode of the diode DA2 and the first end of the inductor LA1. The second end of the output end of the EMI filter U1 is respectively connected to the second end of the first switching tube S1 and the third end of the second switching tube S2. The cathode of the diode DA1 is respectively connected to the third end of the first switching tube S1, the third end of the third switching tube QA1, the first end of the filter capacitor CL and the first end of the load resistor RL. The second end of the third switching tube QA1 is respectively connected to the second end of the inductor LA1 and the third end of the fourth switching tube QA2. The anode of the diode DA2 is respectively connected to the second end of the second switching tube S2, the second end of the fourth switching tube QA2, the second end of the filter capacitor CL and the second end of the load resistor.

[0033] When a surge occurs in the AC power supply AC, for example, a lightning strike at the input will cause a surge in the AC power supply AC, and at this time, a large surge current will be generated. This surge current flows through the first switching tube S1 and the second switching tube S2. Specifically, when a negative lightning strike occurs in the positive half-cycle of the AC power supply AC voltage, the surge current flows from the second end of the output end of the EMI filter U1 through the second switching tube S2, the diode DA2 and the first end of the output end of the EMI filter U1 in sequence; when a positive lightning strike occurs in the negative half-cycle of the AC power supply AC voltage, the surge current flows from the first end of the output end of the EMI filter U1 through the diode DA1, the first switching tube S1 and the second end of the output end of the EMI filter U1 in sequence. Obviously, the surge current may flow through the first switching tube S1 or the second switching tube S2, which may cause the first switching tube S1 or the second switching tube S2 to be damaged. That is, when a surge occurs in the AC power supply, the switching tubes in the slow bridge arm are easily damaged.

[0034] Based on this, the present application provides a switching tube control circuit to achieve soft turn-off of the switching tubes in the slow bridge arm when a surge occurs in the AC power supply AC, thereby reducing the probability of damage to the switching tubes in the slow bridge arm.

[0035] Please refer to Figure 2 , Figure 2 which is a schematic diagram of the composition block diagram of the switching tube control circuit provided by the embodiment of the present application. As Figure 2 shown, the switching tube control circuit 100 includes a detection module 10, a control module 20 and an impedance configuration module 30. Among them, the detection module 10 is connected to the AC power supply AC. The control module 20 is connected to the detection module 10. The impedance configuration module 30 is connected between the control module 20 and the control end of the switching tube SX. The impedance configuration module 30 includes a turn-off branch 31. In some embodiments, the switching tube SX can be any one of the first switching tube S1 and the second switching tube S2, that is, the switching tube SX is any switching tube in the slow bridge arm.

[0036] Specifically, the detection module 10 is configured to detect a signal based on the voltage output of the AC power supply AC. The control module 20 is configured to output a surge protection signal and a control signal when it is determined based on the detection signal that a surge occurs in the AC power supply AC. The turn-off branch 31 is configured such that when it operates and does not receive the surge protection signal, the impedance of the turn-off branch 31 is configured as a first turn-off impedance, and when it operates and receives the surge protection signal, in response to the surge protection signal, the impedance of the turn-off branch 31 is configured as a second turn-off impedance, where the first turn-off impedance is less than the second turn-off impedance, and the turn-off branch 31 operates when the control signal is used to turn off the switch tube SX.

[0037] In summary, when no surge occurs in the AC power supply AC, the impedance of the turn-off branch 31 is configured as the first turn-off impedance; when a surge occurs in the AC power supply AC, the impedance of the turn-off branch 31 is configured as the second turn-off impedance. And since the first turn-off impedance is less than the second turn-off impedance, when a surge occurs in the AC power supply AC, it is equivalent to increasing the impedance of the turn-off branch 31, so that the turn-off rate of the switch tube SX can be effectively reduced, thereby reducing the risk of damage to the switch tube SX.

[0038] In some embodiments, as Figure 3 shown, the impedance configuration module 30 further includes a turn-on branch 32. The turn-on branch 32 is configured such that when it operates, the impedance of the turn-on branch 32 is configured as a conduction impedance, where the turn-on branch operates when the control signal is used to turn on the switch tube SX.

[0039] Please refer to Figure 4 , Figure 4 which exemplarily shows a circuit structure of the impedance configuration module 30. As Figure 4 shown, the turn-off branch 31 includes a first resistor R1, a second resistor R2, and a first controllable switch K1. The combination of the second resistor R2 and the first controllable switch K1 in series is connected in parallel with the first resistor R1, and the combination of the first resistor R1, the second resistor R2, and the first controllable switch K1 is connected between the control module 20 and the control terminal of the switch tube SX.

[0040] Specifically, when the turn-off branch 31 operates and does not receive the surge protection signal, the first controllable switch K1 is configured to be closed, so that the total impedance after the first resistor R1 and the second resistor R2 are connected in parallel is the first turn-off impedance. That is, when the turn-off branch 31 operates and the control module 20 does not output the surge protection signal, the first controllable switch K1 remains closed, and the first resistor R1 and the second resistor R2 are connected in parallel. The impedance of the combination of the first resistor R1 and the second resistor R2 connected in parallel is the first turn-off impedance.

[0041] The shut-off branch 31 is also used for disconnecting the first controllable switch K1 in response to the surge protection signal when the shut-off branch 31 is running and receiving the surge protection signal, so that the impedance of the first resistor R1 is the second shut-off impedance. That is, when the shut-off branch 31 is running and the control module 20 outputs the surge protection signal, the first controllable switch K1 is disconnected, and the impedance of the first resistor R1 is the second shut-off impedance. Obviously, the second shut-off impedance is greater than the first shut-off impedance. Thus, when a surge occurs in the AC power supply AC, it is equivalent to that the impedance of the shut-off branch 31 is increased, so the rate at which the switch tube SX is turned off can be effectively reduced, thereby reducing the risk of damage to the switch tube SX.

[0042] In this embodiment, the shutdown branch 31 further includes a first diode D1 .

[0043] The anode of the first diode D1 is connected to the control end of the switch tube SX, and the combination of the first resistor R1, the second resistor R2 and the first controllable switch K1 is connected to the cathode of the first diode D1.

[0044] Specifically, when the control signal is used to control the switch tube SX to turn off, the first diode D1 is forward-conducted, and the corresponding turn-off branch 31 operates.

[0045] In this embodiment, the enabling branch 32 includes a fifth resistor R5.

[0046] The opening branch 32 further includes a second diode D2 , a fifth resistor R5 is connected between the control module 20 and the anode of the second diode D2 , and a cathode of the second diode D2 is connected to the control end of the switch tube SX.

[0047] Specifically, when the control signal is used to control the switch tube SX to turn on, the second diode D2 is forward-conducted, and the corresponding open branch 32 operates. Then, when the switch tube control circuit 100 works normally, the switch tube SX can be controlled to be in a fully turned-on state to reduce its impedance when turned on and improve the system efficiency during normal operation.

[0048] In this embodiment, the impedance configuration module 30 further includes a resistor RA and a capacitor CA, and the resistor RA and the capacitor CA are used for filtering.

[0049] Please refer to Figure 5 , Figure 5 A circuit structure of the first controllable switch K1 is shown as an example. Figure 5 As shown, the first controllable switch K1 includes a third resistor R3, a fourth resistor R4, an NMOS transistor NM1 and a PMOS transistor PM1.

[0050] Among them, the third resistor R3 is connected between the gate and the source of the NMOS transistor NM1. Both the gate and the source of the NMOS transistor NM1 are connected to the control module 20. The drain of the NMOS transistor NM1 is connected to the gate of the PMOS transistor PM1. The PMOS transistor PM1 is also connected in series with the second resistor R2, that is, the drain of the PMOS transistor PM1 is connected to one end of the second resistor R2, and the source of the PMOS transistor PM1 is connected to the cathode of the first diode D1.

[0051] Specifically, when the turn-off branch 31 operates and the control module 20 outputs a surge signal, the gate voltage of the corresponding NMOS transistor NM1 is at a high level relative to the source voltage, so the NMOS transistor NM1 conducts. Subsequently, the PMOS transistor PM1 conducts. The impedance of the combination of the first resistor R1 and the second resistor R2 in parallel is the first turn-off impedance.

[0052] When the turn-off branch 31 operates and the control module 20 does not output a surge signal, the gate voltage of the corresponding NMOS transistor NM1 is at a low level relative to the source voltage, so the NMOS transistor NM1 is turned off. Subsequently, the PMOS transistor PM1 is also turned off. The impedance of the first resistor R1 is the second turn-off impedance.

[0053] Please refer to Figure 6 , Figure 6 which exemplarily shows another circuit structure of the turn-off branch 31. As Figure 6 shown, the turn-off branch 31 still includes the first resistor R1, the second resistor R2 and the first controllable switch K1. Among them, the combination of the second resistor R2 and the first controllable switch K1 in parallel is connected in series with the first resistor R1, and the combination of the first resistor R1, the second resistor R2 and the first controllable switch K1 is connected between the control module 20 and the control terminal of the switching transistor SX.

[0054] Specifically, the turn-off branch 31 is used to configure the first controllable switch K1 to be closed when the turn-off branch 31 operates and no surge protection signal is received, so that the impedance of the second resistor R2 is the first turn-off impedance. That is, when the turn-off branch 31 operates and the control module 20 does not output a surge protection signal, the first controllable switch K1 remains closed and the second resistor R2 is short-circuited. The impedance of the first resistor R1 is the first turn-off impedance.

[0055] The turn-off branch 31 is also used to disconnect the first controllable switch K1 in response to a surge protection signal when it is operating and receives the surge protection signal, so that the sum of the impedances of the first resistor R1 and the second resistor R2 is the second turn-off impedance. That is, when the turn-off branch 31 is operating and the control module 20 outputs a surge protection signal, the first controllable switch K1 disconnects, and the impedance of the combination of the first resistor R1 and the second resistor R2 is the second turn-off impedance. Obviously, the second turn-off impedance is greater than the first turn-off impedance. Thus, when a surge occurs in the AC power supply AC, it is equivalent to increasing the impedance of the turn-off branch 31, so that the turn-off rate of the switching transistor SX can be effectively reduced, thereby reducing the risk of damage to the switching transistor SX.

[0056] It can be understood that Figure 6 the first controllable switch K1 shown can also be implemented by using the circuit structure as Figure 5 shown. However, what needs to be changed is that in Figure 6 , the PMOS transistor PM1 is in parallel with the second resistor R2, that is, the drain of the PMOS transistor PM1 is connected to one end of the second resistor R2, and the source of the PMOS transistor PM1 is connected to the other end of the second resistor R2.

[0057] Please refer to Figure 7 , Figure 7 which exemplarily shows another implementation manner of the circuit structure of the turn-off branch 31 and the turn-on branch 32. As Figure 7 shown, the connection relationship among the first resistor R1, the second resistor R2, and the first controllable switch K1 is the same as that in Figure 6 , and will not be elaborated here.

[0058] In this embodiment, the turn-off branch 31 further includes a first triode Q1.

[0059] Wherein, the base of the first triode Q1 is connected to the control module 20, the combination of the first resistor R1, the second resistor R2, and the first controllable switch K1 is connected to the emitter of the first triode Q1, and the collector of the first triode Q1 is connected to the control end of the switching transistor SX.

[0060] In this embodiment, the turn-on branch 32 includes a fifth resistor R5 and a second triode Q2. Wherein, the fifth resistor R5 is connected between the control module 20 and the emitter of the second triode Q2, the base of the second triode Q2 is connected to the control module 20, and the collector of the second triode Q2 is connected to the control end of the switching transistor SX.

[0061] Specifically, when the control signal is used to control the switch tube SX to conduct, the control module 20 controls the second triode Q2 to conduct, and the corresponding branch 32 is turned on and operates. Subsequently, when the switch tube control circuit 100 operates normally, it can control the switch tube SX to be in a fully conductive state to reduce its impedance when conducting and improve the system efficiency during normal operation.

[0062] When the control signal is used to control the switch tube SX to turn off, the control module 20 controls the first triode Q1 to conduct, and the corresponding turn-off branch 31 operates. At this time, if the control module 20 does not output a surge protection signal, the first controllable switch K1 is configured to be closed so that the impedance of the second resistor R2 is the first turn-off impedance. That is, when the turn-off branch 31 operates and the control module 20 does not output a surge protection signal, the first controllable switch K1 remains closed and the second resistor R2 is short-circuited. The impedance of the first resistor R1 is the first turn-off impedance.

[0063] If the control module 20 outputs a surge protection signal, the first controllable switch K1 disconnects in response to the surge protection signal so that the sum of the impedances of the first resistor R1 and the second resistor R2 is the second turn-off impedance. That is, when the turn-off branch 31 operates and the control module 20 outputs a surge protection signal, the first controllable switch K1 disconnects, and the impedance of the combination of the first resistor R1 and the second resistor R2 is the second turn-off impedance. Obviously, the second turn-off impedance is greater than the first turn-off impedance. Thus, when a surge occurs in the AC power supply AC, it is equivalent to increasing the impedance of the turn-off branch 31, so that the turn-off rate of the switch tube SX can be effectively reduced, and the risk of damage to the switch tube SX can be reduced.

[0064] Please refer to Figure 8 , Figure 8 which is a schematic diagram of the composition block diagram of the bridge-less circuit provided by the embodiment of the present application. As Figure 8 shown, the bridge-less circuit 1000 includes a first switch tube S1, a second switch tube S2, a detection module 10 and a control module 20 in the switch tube control circuit 100 as in any embodiment of the present application, and an impedance configuration module 30 in two switch tube control circuits 100.

[0065] Among them, the control module 20 is used to output a first control signal and a second control signal. The first control signal is used to control the first switch tube S1 to conduct or turn off, and the second control signal is used to control the second switch tube S2 to conduct or turn off. The first impedance configuration module 30 is connected between one end where the control module 20 outputs the first control signal and the control end of the first switch tube S1, and the second impedance configuration module 30 is connected between one end where the control module 20 outputs the second control signal and the control end of the second switch tube S2. The first switch tube S1 and the second switch tube S2 are connected in series.

[0066] In this embodiment, the control module 20 controls the turn-off branch 31 in the first impedance configuration module 30, the turn-off branch 31 in the second impedance configuration module 30, the first switch tube S1, and the second switch tube S2 respectively. Furthermore, when a surge occurs in the AC power supply AC, the turn-off rate of the first switch tube S1 or the second switch tube S2 can be reduced according to the actual change of the voltage of the AC power supply AC, so as to reduce the risk of damage to the first switch tube S1 and the second switch tube S2.

[0067] In some embodiments, the first switch tube S1 and the second switch tube S2 are Figure 1 the first switch tube S1 and the second switch tube S2 shown.

[0068] In some embodiments, as Figure 9 shown, the control module 20 includes a controller 21, a gate driver 22, and a digital isolator 23, and the detection module 10 includes a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R8.

[0069] Among them, the sixth resistor R6 and the seventh resistor R7 are connected in series between the first terminal of the AC power supply AC and the ground GND. The connection point between the sixth resistor R6 and the seventh resistor R7 is connected to the controller 21. The eighth resistor R8 and the ninth resistor R9 are connected in series between the second terminal of the AC power supply AC and the ground GND. The connection point between the eighth resistor R8 and the ninth resistor R9 is connected to the controller 21. The controller 21 is respectively connected to the digital isolator 23, the gate driver 22, and the second impedance configuration module 30. The digital isolator 23 is connected to the first impedance configuration module 30. The gate driver 22 is respectively connected to the first impedance configuration module 30 and the second impedance configuration module 30.

[0070] Specifically, the voltage at the first terminal of the AC power supply AC is divided by the sixth resistor R6 and the seventh resistor R7 and then input to the ACL pin of the controller 21. The voltage at the second terminal of the AC power supply AC is divided by the eighth resistor R8 and the ninth resistor R9 and then input to the ACN pin of the controller 21. Then the detection signal is the signals received by the ACL pin and the ACN pin of the controller 21. Based on this detection signal, the controller 21 can determine the voltage of the AC power supply AC, and further can determine whether a surge occurs in the AC power supply AC.

[0071] The SRH pin of the controller 21 outputs a third control signal for controlling the conduction or cutoff of the first switching transistor S1 to the HIN pin of the gate driver 22, so that the HO pin of the gate driver 22 outputs a first control signal. Among them, the waveform of the first control signal is the same as that of the third control signal, and the driving ability of the first control signal is stronger than that of the third control signal. When the voltage of the HO pin of the gate driver 22 is high with reference to the voltage of the HS pin of the gate driver 22, the first control signal is used to control the conduction of the first switching transistor S1; when the voltage of the HO pin of the gate driver 22 is low with reference to the voltage of the HS pin of the gate driver 22, the first control signal is used to control the cutoff of the first switching transistor S1. The SRL pin of the controller 21 outputs a fourth control signal for controlling the conduction or cutoff of the second switching transistor S2 to the LIN pin of the gate driver 22, so that the LO pin of the gate driver 22 outputs a second control signal. Among them, the waveform of the second control signal is the same as that of the fourth control signal, and the driving ability of the second control signal is stronger than that of the fourth control signal. When the voltage of the LO pin of the gate driver 22 is high with reference to the voltage of the LS pin of the gate driver 22, the second control signal is used to control the conduction of the second switching transistor S2; when the voltage of the LO pin of the gate driver 22 is low with reference to the voltage of the LS pin of the gate driver 22, the second control signal is used to control the cutoff of the second switching transistor S2. The SURGE pin of the controller 21 is used to output a surge protection signal.

[0072] Relative to the controller 21, the source electrode of the first switching transistor S1 is not grounded with the controller 21 and has a high common-mode voltage. Therefore, a digital isolator 23 is needed to implement the isolation of strong and weak electrical signals. The input power supply of the VDD2 pin of the digital isolator 23 can be provided by the power supply pin (i.e., the HB pin) of the gate driver 22. The output pin OUT of the digital isolator 23 controls the conduction and cutoff of the NMOS transistor NM1 in the first impedance configuration module 30, and further controls the conduction and cutoff of the PMOS transistor PM1 in the first impedance configuration module 30, that is, controls the closing and opening of the first controllable switch K1 in the first impedance configuration module 30.

[0073] Relative to the controller 21, the source electrode of the second switching transistor S2 is grounded with the controller 21. Therefore, the signal output by the SURGE pin of the controller 21 can be directly used to control the conduction and cutoff of the NMOS transistor NM1 in the second impedance configuration module 30, and further control the conduction and cutoff of the PMOS transistor PM1 in the second impedance configuration module 30, that is, control the closing and opening of the first controllable switch K1 in the second impedance configuration module 30.

[0074] In addition, in this embodiment, the gate driver 22 is taken as a half-bridge driver as an example, so a bootstrap diode DA can be integrated inside.

[0075] In this embodiment, the circuit structure of the impedance configuration module 30 is taken as Figure 5 the circuit structure shown. At the same time, devices with auxiliary functions such as filtering or voltage regulation are also exemplarily shown. For example, the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the fifth capacitor C5 for filtering; the zener diode Z1 for voltage regulation; the tenth resistor R10 for current limiting.

[0076] It can be understood that, for the convenience of more clearly showing the specific circuit for controlling the first switching tube S1 and the second switching tube S2, Figure 9 only a partial circuit structure is exemplarily shown. It is easy for those skilled in the art to understand that in actual applications, when the first switching tube S1 and the second switching tube S2 are applied to different application scenarios, other circuits are usually set up to achieve complete functions. For example, when the first switching tube S1 and the second switching tube S2 are applied to a totem-pole bridgeless circuit, as Figure 1 shown, at this time, the complete circuit structure should simultaneously include Figure 1 and Figure 9 the circuit structure of.

[0077] Please refer to Figure 10 , Figure 10 which is a flowchart of the control method provided by the embodiment of the present application based on the bridgeless circuit as Figure 8 and Figure 9 shown. As Figure 10 shown, the control method includes the following method steps:

[0078] Step 1001: When it is determined based on the detection signal output by the detection module that the AC power supply is in the positive half cycle and a surge occurs in the AC power supply, control the first controllable switch in the second impedance configuration module to disconnect, and control the second switching tube to turn off.

[0079] Step 1002: When it is determined based on the detection signal output by the detection module that the AC power supply is in the negative half cycle and a surge occurs in the AC power supply, control the first controllable switch in the first impedance configuration module to disconnect, and control the first switching tube to turn off.

[0080] Please refer to Figure 9 and Figure 11 together, wherein, in Figure 11 , the signals from top to bottom in the vertical direction are respectively the voltage VAC of the AC power supply AC; the surge detection signal VS1 generated when it is determined in the controller 21 that a surge occurs in the AC power supply; the signal VSURGE output from the SURGE pin of the controller 21; the signal VSRH output from the SRH pin of the controller 21 (i.e., the third control signal corresponding to the above embodiment); the signal VSRL output from the SRL pin of the controller 21 (i.e., the fourth control signal corresponding to the above embodiment). Figure 11The abscissa in [it] is time.

[0081] Specifically, before time T1, there is no surge in the AC power supply AC, no surge detection signal VS1 is generated in the controller 21, and the signal VSURGE output by the controller 21 remains high. The NMOS transistor NM1 and the PMOS transistor PM1 in the two impedance configuration modules 30 are both controlled to conduct, and the first switch tube S1 and the second switch tube S2 are both normally conducting or off.

[0082] At time T1, a surge occurs in the AC power supply AC. At this time, it is similar to a negative lightning strike in the positive half-cycle of the AC power supply AC voltage. Corresponding to the AC power supply AC being in the positive half-cycle and a surge occurring in the AC power supply AC, a surge detection signal VS1 is generated in the controller 21. At the same time, the signal VSURGE output by the controller 21 switches from high level to low level, and the first controllable switch K1 in the second impedance configuration module 30 is turned off, that is, the NMOS transistor NM1 and the PMOS transistor PM1 in the second impedance configuration module 30 are both controlled to turn off. At the same time, the signal VSRL output by the SRL pin of the controller 21 switches from high level to low level. At this time, the second control signal is used to control the second switch tube S2 to turn off. Since the PMOS transistor PM1 is turned off, the impedance of the turn-off branch 31 increases from the first turn-off impedance to the second turn-off impedance, which can effectively reduce the turn-off rate of the second switch tube S2, thereby reducing the risk of damage to the second switch tube S2. Until time T2, the surge ends, and the surge detection signal VS1 switches to low level. After that, the signal VSURGE also returns to high level so that the second switch tube S2 can be normally turned off under normal conditions in the future.

[0083] At time T3, a surge occurs in the AC power supply AC. At this time, it is similar to a positive lightning strike in the negative half-cycle of the AC power supply AC voltage. Corresponding to the AC power supply AC being in the negative half-cycle and a surge occurring in the AC power supply AC, a surge detection signal VS1 is generated in the controller 21. At the same time, the signal VSURGE output by the controller 21 switches from high level to low level, and the first controllable switch K1 in the first impedance configuration module 30 is turned off, that is, the NMOS transistor NM1 and the PMOS transistor PM1 in the first impedance configuration module 30 are both controlled to turn off. At the same time, the signal VSRH output by the SRH pin of the controller 21 switches from high level to low level. At this time, the first control signal is used to control the first switch tube S1 to turn off. Since the PMOS transistor PM1 is turned off, the impedance of the turn-off branch 31 increases from the first turn-off impedance to the second turn-off impedance, which can effectively reduce the turn-off rate of the first switch tube S1, thereby reducing the risk of damage to the first switch tube S1. Until time T4, the surge ends, and the surge detection signal VS1 switches to low level. After that, the signal VSURGE also returns to high level so that the first switch tube S1 can be normally turned off under normal conditions in the future.

[0084] The above are only embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

[0085] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; under the idea of the present application, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order. Those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present application.

Claims

1. A switch tube control circuit, characterized in that: include: A detection module, connected to the AC power supply, and configured to output a detection signal based on the voltage of the AC power supply; A control module, connected to the detection module, configured to output a surge protection signal and a control signal when it is determined based on the detection signal that a surge occurs in the AC power supply; An impedance configuration module is connected between the control module and the control end of the switch tube, and includes a shutdown branch. The shutdown branch is used to configure the impedance of the shutdown branch to be a first shutdown impedance when the shutdown branch is running and has not received the surge protection signal, and is used to configure its impedance to be a second shutdown impedance in response to the surge protection signal when the shutdown branch is running and receives the surge protection signal, wherein the first shutdown impedance is smaller than the second shutdown impedance, and the shutdown branch operates when the control signal is used to control the switch tube to shut down.

2. The switch tube control circuit according to claim 1, characterized in that: The shut-off branch includes a first resistor, a second resistor and a first controllable switch; Do one of the following two things: Mode A: the second resistor and the first controllable switch are connected in series and connected in parallel with the first resistor; The shut-off branch is used for, when the first controllable switch is in operation and does not receive the surge protection signal, being configured to be closed so that the total impedance of the first resistor and the second resistor connected in parallel is the first shut-off impedance; The shut-off branch is further configured to disconnect the first controllable switch in response to the surge protection signal when the first controllable switch is in operation and receives the surge protection signal, so that the impedance of the first resistor is the second shut-off impedance; Mode B: a combination of the second resistor and the first controllable switch connected in parallel is connected in series with the first resistor; The shut-off branch is used for, when the shut-off branch is in operation and does not receive the surge protection signal, the first controllable switch is configured to be closed so that the impedance of the second resistor is the first shut-off impedance; The shutdown branch is also used for disconnecting the first controllable switch in response to the surge protection signal when the shutdown branch is in operation and receives the surge protection signal, so that the sum of the impedances of the first resistor and the second resistor is the second shutdown impedance.

3. The switch tube control circuit according to claim 2, characterized in that: The first controllable switch includes a third resistor, a fourth resistor, an NMOS transistor and a PMOS transistor; The third resistor is connected between the gate and source of the NMOS tube, the gate and source of the NMOS tube are both connected to the control module, and the drain of the NMOS tube is connected to the gate of the PMOS tube, wherein when mode A is executed, the PMOS tube is also connected in series with the second resistor, and when mode B is executed, the PMOS tube is also connected in parallel with the second resistor.

4. The switch tube control circuit according to claim 2 or 3, characterized in that: The shut-off branch further includes a first diode; The anode of the first diode is connected to the control end of the switch tube, and the combination of the first resistor, the second resistor and the first controllable switch is connected to the cathode of the first diode.

5. The switch tube control circuit according to claim 2 or 3, characterized in that: The shut-off branch also includes a first triode; The base of the first transistor is connected to the control module, the combination of the first resistor, the second resistor and the first controllable switch is connected to the emitter of the first transistor, and the collector of the first transistor is connected to the control end of the switch tube.

6. The switch tube control circuit according to claim 1, characterized in that: The impedance configuration module further includes an on-branch, wherein the impedance of the on-branch is configured as an on-impedance when the on-branch is in operation, wherein the on-branch is in operation when the control signal is used to control the switch tube to be turned on.

7. The switch tube control circuit according to claim 6, characterized in that: The open branch includes a fifth resistor; The opening branch also includes a second diode, the fifth resistor is connected between the control module and the anode of the second diode, and the cathode of the second diode is connected to the control end of the switch tube; or, the opening branch also includes a second transistor, the fifth resistor is connected between the control module and the emitter of the second transistor, the base of the second transistor is connected to the control module, and the collector of the second transistor is connected to the control end of the switch tube.

8. A bridgeless circuit, characterized in that: It comprises a first switch tube, a second switch tube, a detection module and a control module in the switch tube control circuit according to any one of claims 1 to 7, and an impedance configuration module in the two switch tube control circuits; The control module is used to output a first control signal and a second control signal; The first impedance configuration module is connected between one end of the control module outputting the first control signal and the control end of the first switch tube, and the second impedance configuration module is connected between one end of the control module outputting the second control signal and the control end of the second switch tube, and the first switch tube and the second switch tube are connected in series.

9. The bridgeless circuit according to claim 8, characterized in that: The control module includes a digital isolator, a controller and a gate driver, and the detection module includes a sixth resistor, a seventh resistor, an eighth resistor and a ninth resistor; The sixth resistor and the seventh resistor are connected in series between the first end of the AC power supply and the ground, and the connection point between the sixth resistor and the seventh resistor is connected to the controller, and the eighth resistor and the ninth resistor are connected in series between the second end of the AC power supply and the ground, and the connection point between the eighth resistor and the ninth resistor is connected to the controller; The controller is connected to the digital isolator, the gate driver and the second impedance configuration module respectively, the digital isolator is connected to the first impedance configuration module, and the gate driver is connected to the first impedance configuration module and the second impedance configuration module respectively.

10. A control method based on the bridgeless circuit according to claim 8 or 9, characterized in that: include: When it is determined based on the detection signal output by the detection module that the AC power source is in a positive half cycle and a surge occurs in the AC power source, the first controllable switch in the second impedance configuration module is controlled to be disconnected, and the second switch tube is controlled to be turned off; Based on the detection signal output by the detection module, it is determined that when the AC power supply is in the negative half cycle and the When a surge occurs in the AC power supply, the first controllable switch in the first impedance configuration module is controlled to be disconnected, And control the first switch tube to be turned off.

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