Overvoltage protection circuit of semiconductor switch
By using the protection circuit of the free-current clamp module and the energy storage and energy storage module in the semiconductor switch, the overvoltage problem of the semiconductor switch when the circuit is cut off is solved, the voltage withstand voltage requirements is reduced, the cost and internal resistance are reduced, and the difficulty of heat dissipation design is reduced.
Patent Information
- Application Number
- CN202421776591.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-25
- Publication Date
- 2025-06-27
- Estimated Expiration
- 2034-07-25
AI Technical Summary
When the existing semiconductor switches cut off the loop, due to the presence of inductor in the line, they will induce a higher voltage, which will easily break down the semiconductor switch overvoltage, and existing solutions such as parallel varistors or TVS tubes will increase cost and internal resistance.
The protection circuit including a freewheeling clamp module and an energy storage and energy storage module is adopted. The freewheeling clamp module clamps the voltage when the semiconductor switch is turned off to the peak of the input voltage. The energy storage and energy storage and energy storage module consumes the residual energy after being disconnected to avoid high voltage induction.
Reduced the voltage withstand voltage requirements for semiconductor switches. Choosing a semiconductor switch with lower voltage withstand voltage can reduce cost and internal resistance, reduce the difficulty of heat dissipation design, and avoid voltage spikes.
Smart Images
Figure CN223040003U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of semiconductor switches, in particular to an overvoltage protection circuit for a semiconductor switch. Background Art
[0002] Semiconductor switches are various switching devices made of semiconductor materials, including triodes, MOS transistors, insulated gate bipolar transistors, etc. Due to their excellent switching performance, they are widely used in various circuits that require switching control.
[0003] As Figure 1 shown, it is a common current-limiting protection switch circuit in the prior art. When the controller detects a short circuit or overcurrent in the circuit, it will cut off the loop through the semiconductor switch SP to protect the circuit devices and prevent accidents. However, when the semiconductor switch cuts off the loop, due to the existence of inductance in the circuit (the inductance generated by the inductive components connected in the circuit or the circuit itself), a relatively high voltage will be induced across the semiconductor switch. The larger the inductance and the faster the cut-off speed, the higher the induced voltage, which is likely to overvoltage breakdown the semiconductor switch.
[0004] To solve this problem, the prior art mostly adopts the scheme of connecting a varistor or a TVS tube in parallel across the semiconductor switch. However, both of these two schemes have the following problems: In order to accelerate the cut-off speed of the semiconductor switch, the clamping voltage must be increased as much as possible; it is generally set at 500 - 600V so that the residual energy can be released quickly; when the clamping voltage is high, the semiconductor switch must also have a high withstand voltage level, and semiconductor switches with high withstand voltage are usually costly, have large internal resistance, and large heat dissipation. Content of the Utility Model
[0005] The utility model provides an overvoltage protection circuit for a semiconductor switch, which can reduce the requirement for the withstand voltage level of the semiconductor switch.
[0006] To solve the above problems, the utility model adopts the following technical solutions:
[0007] An embodiment of the present utility model provides an overvoltage protection circuit for a semiconductor switch, which includes a first input terminal, a semiconductor switch, a load, a second input terminal, and a protection module; the semiconductor switch includes two connection terminals and a control terminal, and the two connection terminals are used to conduct or disconnect according to the level signal of the control terminal; the first input terminal is connected to one connection terminal of the semiconductor switch, and the other connection terminal of the semiconductor switch, the load, and the second input terminal are connected in sequence; the connection terminal of the semiconductor switch connected to the first input terminal is connected to one end of the protection module, and the end of the load connected to the second input terminal is connected to the other end of the protection module; the protection module includes a freewheeling clamping module and an energy storage and energy release module, the freewheeling clamping module is used to clamp the voltage across the semiconductor switch when it is turned off to the peak value of the input voltage, and the energy storage and energy release module is used to consume the residual energy of the semiconductor switch after it is turned off.
[0008] In some embodiments, the freewheeling clamping module includes a first diode, a second diode, a third diode, and a fourth diode. The connection terminal of the semiconductor switch connected to the first input terminal is connected to both the positive electrode of the first diode and the negative electrode of the third diode. The negative electrode of the first diode is connected to the negative electrode of the second diode, the positive electrode of the third diode is connected to the positive electrode of the fourth diode, and the end of the load connected to the second input terminal is connected to both the positive electrode of the second diode and the negative electrode of the fourth diode.
[0009] In some embodiments, the energy storage and energy release module includes an energy storage capacitor, a power-consuming resistor, and an energy release switch. The energy release switch includes two conducting terminals and an enabling terminal, and the two conducting terminals are used to conduct or disconnect according to the level signal of the enabling terminal; both ends of the energy storage capacitor are respectively connected to the negative electrode of the second diode and the positive electrode of the fourth diode. The negative electrode of the second diode, the power-consuming resistor, and one conducting terminal of the MOS transistor are connected in sequence, and the other conducting terminal of the MOS transistor is connected to the positive electrode of the fourth diode.
[0010] In some embodiments, the energy release switch is a MOS transistor, the drain and source of the MOS transistor are respectively the two conducting terminals, and the gate of the MOS transistor is the enabling terminal.
[0011] In some embodiments, the first input terminal is connected to the live wire of the mains electricity, and the second input terminal is connected to the neutral wire of the mains electricity.
[0012] In some embodiments, it further includes a current detection module and a control module. The control module is connected to the control terminal of the semiconductor switch; the current detection module is used to detect the current in the main line formed by connecting the first input terminal, the semiconductor switch, the load, and the second input terminal in series in sequence and send the detected current value to the control module, and the control module is used to output a level signal to the control terminal of the semiconductor switch according to the detected current value.
[0013] In some embodiments, a current detection module and a control module are further included. The control module is connected to the control end of the semiconductor switch and the enable end of the energy release switch. The current detection module is configured to detect the current in the main line formed by sequentially connecting the first input end, the semiconductor switch, the load, and the second input end in series, and send the detected current value to the control module. The control module is configured to respectively output level signals to the control end of the semiconductor switch and the enable end of the energy release switch according to the detected current value.
[0014] The utility model has at least the following beneficial effects: The freewheeling clamping module of the utility model can clamp the voltage at both ends of the semiconductor switch when it is turned off to the peak value of the input voltage, thereby reducing the clamping voltage. A semiconductor switch with a lower withstand voltage requirement can be selected. The semiconductor switch with a lower withstand voltage requirement has a lower cost, a smaller internal resistance, and lower heat dissipation under the same current, reducing the difficulty of the heat dissipation design. The energy storage and energy release module is used to consume the residual energy of the semiconductor switch after it is turned off, avoiding the induction of a relatively high voltage spike at both ends of the semiconductor switch. Description of the Drawings
[0015] Figure 1 It is a schematic structural diagram of a current-limiting protection switch circuit in the prior art;
[0016] Figure 2 It is a schematic structural diagram of an overvoltage protection circuit of a semiconductor switch according to an embodiment of the utility model;
[0017] Figure 3 It is a schematic structural diagram of an overvoltage protection circuit of a semiconductor switch according to another embodiment of the utility model;
[0018] Figure 4 It is a schematic structural diagram of an overvoltage protection circuit of a semiconductor switch according to still another embodiment of the utility model.
[0019] Among them, the reference numerals are:
[0020] First input end 10, semiconductor switch 20, load 30, second input end 40, protection module 50, freewheeling clamping module 51, energy storage and energy release module 52, current detection module 60, control module 70. Detailed Embodiments
[0021] The present utility model provides the following description with reference to the drawings to help a comprehensive understanding of various embodiments of the present utility model as defined by the claims and their equivalents. The description includes various specific details to assist in understanding, but these details should be regarded as merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the various embodiments described herein without departing from the scope and spirit of the present utility model.
[0022] In the description of the present utility model, orientation descriptions are involved. For example, the orientations or positional relationships indicated by up, down, front, back, left, right, etc. are based on the orientations or positional relationships shown in the drawings. This is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model.
[0023] It should be understood that when an element (for example, the first element) is "connected" to another element (for example, the second element), the element can be directly connected to the other element, or there can be an intermediate element (for example, the third element) between the element and the other element.
[0024] An embodiment of the present utility model provides an overvoltage protection circuit for a semiconductor switch, as Figure 2 shown, which includes a first input terminal 10, a semiconductor switch 20, a load 30, a second input terminal 40, and a protection module 50. The first input terminal 10 and the second input terminal 40 are used to input AC signals. The load 30 is a device that needs electricity in the circuit, mainly an electrical appliance at the user end. The semiconductor switch 20 includes two connection terminals and a control terminal. The two connection terminals are used to conduct or disconnect according to the level signal of the control terminal to achieve the switching function. One connection terminal of the first input terminal 10 is connected to the semiconductor switch 20, and the other connection terminal of the semiconductor switch 20, the load 30, and the second input terminal 40 are connected in sequence. The first input terminal 10, the semiconductor switch 20, the load 30, and the second input terminal 40 are connected in series in sequence to form a main line. When a short circuit or overcurrent occurs in the main line, the two connection terminals of the semiconductor switch 20 will disconnect to cut off the circuit and protect the devices in the circuit to prevent accidents.
[0025] The connection terminal of the semiconductor switch 20 connected to the first input terminal 10 is connected to one end of the protection module 50, and the end of the load 30 connected to the second input terminal 40 is connected to the other end of the protection module 50. The protection module 50 includes a freewheeling clamping module 51 and an energy storage and energy release module 52. The freewheeling clamping module 51 is used to clamp the voltage across the semiconductor switch 20 when it is disconnected to the peak value of the input voltage. Here, the input voltage is the voltage input by the first input terminal 10 and the second input terminal 40. For example, when the input voltage is an AC voltage of 220V, the clamping voltage is about 311V, while the clamping voltage in the traditional method is 500 - 600V. This reduces the clamping voltage, and a semiconductor switch with a lower withstand voltage requirement can be selected. The semiconductor switch with a lower withstand voltage requirement has a lower cost, a smaller internal resistance, and lower heat dissipation under the same current, which can reduce the difficulty of the heat dissipation design. The energy storage and energy release module 52 is used to consume the residual energy of the semiconductor switch 20 after it is disconnected to avoid inducing a higher voltage spike across the semiconductor switch 20.
[0026] In some embodiments, the semiconductor switch 20 may include a triode, a MOS transistor, and an insulated gate bipolar transistor. Preferably, the semiconductor switch 20 includes two MOS transistors. The sources of the two MOS transistors are connected in series. The drains of the two MOS transistors are respectively the two connection ends of the semiconductor switch 20. The gates of the two MOS transistors are connected to form the control end of the semiconductor switch 20.
[0027] In some embodiments, as Figure 3 shown, the freewheeling clamping module includes a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The connection end of the semiconductor switch SP connected to the first input terminal Lin is connected to both the positive electrode of the first diode and the negative electrode of the third diode. The negative electrodes of the first diode and the second diode are connected. The positive electrodes of the third diode and the fourth diode are connected. One end of the load RL connected to the second input terminal N is connected to both the positive electrode of the second diode and the negative electrode of the fourth diode. The first diode D1, the second diode D2, the third diode D3, and the fourth diode D4 form a rectifier bridge circuit for rectifying the alternating current input at the first input terminal and the second input terminal. When a short circuit or overcurrent occurs in the main line, the semiconductor switch SP disconnects, cutting off the loop. The voltage across the semiconductor switch SP approaches the peak voltage of the first input terminal and the second input terminal. Therefore, the voltage withstand requirement for the semiconductor switch can be relatively low.
[0028] Further, the energy storage and energy release module includes an energy storage capacitor C, a power dissipation resistor Rs, and an energy release switch Qs. The energy release switch includes two conduction ends and an enable end. The two conduction ends are used to conduct or disconnect according to the level signal of the enable end. The two ends of the energy storage capacitor are respectively connected to the negative electrode of the second diode and the positive electrode of the fourth diode. The negative electrode of the second diode, the power dissipation resistor, and one conduction end of the MOS transistor are connected in sequence. The other conduction end of the MOS transistor and the positive electrode of the fourth diode are connected.
[0029] When the current flows in the forward direction, that is, flows sequentially along the first input terminal, the semiconductor switch, and the load, if a short circuit or overcurrent occurs in the main line, the semiconductor switch SP disconnects, cutting off the loop. Due to the presence of the inductor in the main line or the inductor in the front-end device, the current in the line cannot change suddenly. And because there is a freewheeling path D1, the current in the line inductor freewheels into the main line, causing the main line voltage to rise. However, due to the presence of the energy storage capacitor C, the rise of the main line voltage is slow. At the same time, the energy release switch Qs is turned on, and the energy of the main line is gradually consumed through the power dissipation resistor Rs, causing the main line voltage to decrease.
[0030] When the current flows in the reverse direction, that is, flows sequentially along the load, the semiconductor switch, and the first input terminal, if a short circuit or overcurrent occurs in the main line, the semiconductor switch SP disconnects to cut off the circuit. Due to the inductance in the main line or the inductance in the front-end device, the current in the line cannot change suddenly. And because there is a freewheeling path D2, the current in the line inductance freewheels into the main line, causing the main line voltage to rise. However, due to the existence of the energy storage capacitor C, the rise of the main line voltage is slow. At the same time, the energy release switch Qs is turned on, and the energy of the main line is gradually consumed through the energy-consuming resistor Rs, which also reduces the main line voltage.
[0031] In this embodiment, by reasonably designing the values of the energy storage capacitor C and the energy-consuming resistor Rs, and dynamically adjusting the conduction time of the energy release switch Qs, the energy release speed of the main line can be dynamically adjusted, so that the residual energy in the line after the semiconductor switch is turned off can be dynamically consumed, and the capacity of the consumed residual energy is adjustable. It can avoid being limited by the capacity of the protected device like the prior art. For different inductance parameters in different lines, the consumption of residual energy can be achieved, enabling it to be applied to inductive lines, thus broadening the application range of the overvoltage protection circuit of the semiconductor switch in this embodiment.
[0032] In this embodiment, the energy storage capacitor C can be selected from electrolytic capacitors, ceramic capacitors, thin-film capacitors, etc.
[0033] In some embodiments, the energy release switch is a MOS transistor. The drain and source of the MOS transistor are respectively two conduction terminals, and the gate of the MOS transistor is the enable terminal. Of course, according to actual needs, the energy release switch may also include a triode or an insulated gate bipolar transistor.
[0034] In some embodiments, the first input terminal is connected to the live wire of the mains, and the second input terminal is connected to the neutral wire of the mains. The first input terminal and the second input terminal can input alternating current. At the same time, the overvoltage protection circuit of the semiconductor switch in this embodiment can be applied to high-voltage application scenarios such as electrical fire prevention and current limiting protectors.
[0035] In some embodiments, such as Figure 4As shown, the overvoltage protection circuit of the semiconductor switch in this embodiment further includes a current detection module 60 and a control module 70, and the control module 70 is connected to the control terminal of the semiconductor switch SP. The current detection module 60 is used to detect the current in the main line formed by sequentially connecting the first input terminal Lin, the semiconductor switch SP, the load RL, and the second input terminal N in series and send the detected current value to the control module 60. The control module 70 is used to output a level signal to the control terminal of the semiconductor switch according to the current value detected by the current detection module 60. When a short circuit or overcurrent occurs in the main line, the current in the main line is very large. Therefore, the control module 70 will judge whether the current value detected by the current detection module 60 is greater than the protection threshold. If it is greater than the protection threshold, it means that an abnormal phenomenon such as a short circuit or overcurrent has occurred in the main line. The control module 70 sends a level signal to the control terminal of the semiconductor switch SP to make the semiconductor switch SP turn off, so that the semiconductor switch SP turns off.
[0036] Further, the control module 70 is also connected to the enable terminal of the energy release switch Qs, and the control module is also used to output a level signal to the enable terminal of the energy release switch according to the detected current value. When the control module 70 determines that the current value detected by the current detection module 60 is greater than the protection threshold, the control module 70 sends a level signal to the control terminal of the semiconductor switch SP to make the semiconductor switch SP turn off, so that the semiconductor switch SP turns off, and at the same time sends a level signal to the enable terminal of the energy release switch to make the energy release switch turn on, so that the residual energy on the main line can be consumed by the energy dissipation resistor Rs, and the main line voltage decreases.
[0037] In this embodiment, by using the same control module 70 to control the conduction or disconnection of the semiconductor switch and the energy release switch, the circuit structure can be simplified.
[0038] In the above embodiment, the current detection module 60 may include a current transformer, and the current transformer is used to detect the current in the main line. The current detection module 60 can send the detected current to the control module 70 by means of wired connection or wireless communication.
[0039] The control module 70 may include a single-chip microcomputer, a DSP chip, or a programmable logic device.
[0040] The terms and words used in the above description and claims are not limited to their literal meanings, but are only used by the applicant to enable a clear and consistent understanding of the present invention. Therefore, those skilled in the art should clearly understand that the above description of various embodiments of the present invention is only for illustration, rather than for limiting the present invention as defined by the appended claims and their equivalents.
Claims
1. An overvoltage protection circuit for a semiconductor switch, characterized in that: It includes a first input terminal, a semiconductor switch, a load, a second input terminal and a protection module; the semiconductor switch includes two connection terminals and a control terminal, and the two connection terminals are used to be turned on or off according to the level signal of the control terminal; the first input terminal is connected to a connection terminal of the semiconductor switch, and the other connection terminal of the semiconductor switch, the load and the second input terminal are connected in sequence; the connection terminal of the semiconductor switch connected to the first input terminal is connected to one end of the protection module, and the end of the load connected to the second input terminal is connected to the other end of the protection module; the protection module includes a freewheeling clamping module and an energy storage and release module, the freewheeling clamping module is used to clamp the voltage at both ends of the semiconductor switch to the peak value of the input voltage when the semiconductor switch is disconnected, and the energy storage and release module is used to consume the residual energy of the semiconductor switch after it is disconnected.
2. The overvoltage protection circuit of a semiconductor switch according to claim 1, characterized in that: The freewheeling clamp module includes a first diode, a second diode, a third diode and a fourth diode. The connection end of the semiconductor switch connected to the first input end is connected to the anode of the first diode and the cathode of the third diode, the cathode of the first diode is connected to the cathode of the second diode, the anode of the third diode is connected to the anode of the fourth diode, and one end of the load connected to the second input end is connected to the anode of the second diode and the cathode of the fourth diode.
3. The overvoltage protection circuit of a semiconductor switch according to claim 2, characterized in that: The energy storage and release module includes an energy storage capacitor, an energy consumption resistor and an energy release switch, and the energy release switch includes two conduction ends and an enable end, and the two conduction ends are used to be turned on or off according to the level signal of the enable end; the two ends of the energy storage capacitor are respectively connected to the cathode of the second diode and the anode of the fourth diode, the cathode of the second diode, the energy consumption resistor and a conduction end of the MOS tube are connected in sequence, and the other conduction end of the MOS tube is connected to the anode of the fourth diode.
4. The overvoltage protection circuit of a semiconductor switch according to claim 3, characterized in that: The energy release switch is a MOS tube, the drain and source of the MOS tube are two conduction ends respectively, and the gate of the MOS tube is an enable end.
5. The overvoltage protection circuit of a semiconductor switch according to claim 1, characterized in that: The first input end is connected to the live wire of the mains, and the second input end is connected to the neutral wire of the mains.
6. The overvoltage protection circuit of a semiconductor switch according to claim 1, 2 or 5, characterized in that: It also includes a current detection module and a control module, wherein the control module is connected to the control end of the semiconductor switch; the current detection module is used to detect the current in the main line formed by sequentially connecting the first input end, the semiconductor switch, the load and the second input end and send the detected current value to the control module, and the control module is used to output a level signal to the control end of the semiconductor switch according to the detected current value.
7. The overvoltage protection circuit of a semiconductor switch according to claim 3 or 4, characterized in that: It also includes a current detection module and a control module, wherein the control module is connected to the control end of the semiconductor switch and the enable end of the energy release switch; the current detection module is used to detect the current in the main line formed by sequentially connecting the first input end, the semiconductor switch, the load and the second input end and send the detected current value to the control module, and the control module is used to output level signals to the control end of the semiconductor switch and the enable end of the energy release switch respectively according to the detected current value.