CN112448702B - Drive protection circuit, method and electrical equipment - Google Patents

Abstract

The present invention discloses a driving protection circuit, method and electrical equipment. The circuit includes: a driving power supply, which is used to convert an input first voltage into a second voltage and a third voltage, the second voltage is output to a switch driving circuit, and is used to drive a power switch tube; the third voltage is output to an operation circuit; the operation circuit is used to judge whether the second voltage is within a preset interval according to the third voltage, and output a control signal according to the judgment result; the switch driving circuit, whose input end is connected to the operation circuit, is used to control itself to open or close according to the control signal. Through the present invention, it is possible to avoid the driving voltage being too high or too low, which may cause adverse effects on the power switch tube, and improve the stability and safety of the power switch tube.

Description

A driving protection circuit, method and electrical equipment

Technical Field

The present invention relates to the technical field of electronic circuits, and in particular to a driving protection circuit, method and electrical equipment.

Background Art

The driving protection circuit of the power switch tube (such as the Insulated Gate Bipolar Transistor, IGBT) is the key to ensure the stable operation of the power switch tube. If the driving is poor, it will not only shorten the life of the power device, but also paralyze the entire system.

When the power switch is turned on, the drive circuit needs to provide a forward voltage of a certain amplitude, which is sufficient to fully saturate the IGBT. In theory, as long as the forward voltage VGE> forward voltage threshold VGEth, it can be turned on. The higher the forward drive voltage, the lower the saturation voltage drop VCEsat of the power switch, and the lower the conduction loss. However, if the gate is too high, the short-circuit current of the device will be larger, the short-circuit duration will be shorter, the power loss will be greater, and the reverse recovery overvoltage of the freewheeling diode will increase. If the drive voltage is too low, the power switch will not be fully saturated, and it will work in the linear active area. The current and voltage are very large, the dissipated power is too large, and the junction temperature rises, causing the tube to explode or burn. It can be seen that too high or too low a drive voltage will have an adverse effect on the power switch.

With regard to the problem in the prior art that the driving voltage is too high or too low, which has an adverse effect on the power switch tube, no effective solution has been proposed yet.

Summary of the invention

The embodiments of the present invention provide a driving protection circuit, method and electrical equipment to solve the problem in the prior art that the driving voltage is too high or too low, causing adverse effects on the power switch tube.

In order to solve the above technical problems, the present invention provides a driving protection circuit, wherein the circuit comprises:

A driving power supply, used for converting an input first voltage into a second voltage and a third voltage,

The second voltage is output to the first input terminal of the switch driving circuit to drive the power switch tube; the third voltage is output to the operation circuit;

The operation circuit is used to determine whether the second voltage is within a preset range according to the third voltage, and output a control signal according to the determination result;

The switch driving circuit has a second input terminal connected to the operation circuit, and is used to control itself to be turned on or off according to the control signal.

Furthermore, the first output end of the driving power supply is connected to the first input end of the switch driving circuit, and the first output end of the driving power supply is also connected to the first end of the voltage divider circuit, the second end of the voltage divider circuit is grounded, the output end of the voltage divider circuit is the second output end of the driving power supply, and the second output end is connected to the input end of the operation circuit, for outputting the third voltage to the operation circuit.

Furthermore, the voltage divider circuit comprises at least a first resistor and a second resistor which are arranged in series, and a line between the first resistor and the second resistor is connected to an input end of the operation circuit.

Furthermore, the operation circuit includes:

a first comparator, wherein a first input terminal of the comparator is connected to the driving power supply to receive the third voltage, a second input terminal of the comparator is input with the first reference voltage, and an output terminal of the comparator is connected with the input terminal of the switch driving circuit; the first comparator is used to output a high level signal when the third voltage is greater than the first reference voltage, and output a low level signal when the third voltage is less than or equal to the first reference voltage;

a second comparator, wherein a first input terminal of the second comparator inputs a second reference voltage, a second input terminal of the second comparator is connected to the driving power supply to receive the third voltage, and an output terminal of the second comparator is connected to an input terminal of the switch driving circuit; the second comparator is used to output a high level signal when the third voltage is less than the second reference voltage, and output a low level signal when the third voltage is greater than or equal to the second reference voltage;

A third resistor has a first end thereof input with an initial voltage, and a second end thereof connected to output ends of the first comparator and the second comparator, and is used for dividing the initial voltage.

Furthermore, the operation circuit is specifically configured to: output a high level signal when the first comparator and the second comparator simultaneously output high level signals; and output a low level signal when at least one of the first comparator and the second comparator outputs a low level signal.

Furthermore, the switch driving circuit comprises:

A photocoupler, wherein a first terminal thereof inputs a pulse width modulation (PWM) signal, a second terminal thereof is grounded, a third terminal thereof is connected to the operation circuit to receive the control signal, a fourth terminal thereof is connected to the driving power supply to receive the second voltage, and a fifth terminal thereof is connected to the gate of the power switch tube; wherein the photocoupler is turned on when the control signal is a high-level signal, controls the on-off timing of the power switch tube according to the PWM signal, and is blocked when the control signal is a low-level signal, so that the power switch tube is always kept in an off state.

Furthermore, the driving protection circuit further includes:

A microcontroller unit MCU, whose input end is connected to the operation circuit and whose output end is connected to the switch drive circuit, is used to determine whether to block the PWM signal input by the switch drive circuit according to the control signal output by the operation circuit; wherein, when the PWM signal input by the switch drive circuit is blocked, the power switch tube always remains in the off state.

Furthermore, the driving protection circuit further includes:

a unidirectional conductive element and a fourth resistor, wherein the unidirectional conductive element and the fourth resistor are arranged in series between the output end of the switch driving circuit and the gate of the power switch tube;

The fifth resistor is arranged in parallel at two ends of a series branch formed by the unidirectional conductive element and the fourth resistor.

Furthermore, the driving protection circuit further includes:

A capacitor and a sixth resistor, wherein the capacitor and the sixth resistor are arranged in series between the gate and the emitter of the power switch tube.

The present invention also provides an electrical device, including a power switch tube, wherein the electrical device includes the above-mentioned drive protection circuit.

Furthermore, the electrical equipment includes at least one of the following: an air conditioner, a washing machine, a refrigerator, a water heater, a fan, a dryer, an air purifier, a water purifier, and a water purifier.

The present invention further provides a driving protection method, which is applied to the driving protection circuit according to any one of claims 1 to 9, characterized in that the method comprises:

Converting the input first voltage into a second voltage and a third voltage and then outputting the converted voltage;

Determine whether the second voltage is within a preset range based on the third voltage, and output a control signal based on the determination result to control the switch drive circuit to be turned on or off; wherein the input end of the switch drive circuit also receives the second voltage to drive the power switch tube.

Further, judging whether the second voltage is within a preset interval according to the third voltage, and outputting a control signal according to the judgment result to control the switch driving circuit to be turned on or off, including:

If the third voltage is greater than the first reference voltage and less than the second reference voltage, it is determined that the second voltage is within a preset range, and a high level signal is output to control the switch driving circuit to turn on;

If the third voltage is less than or equal to the first reference voltage, and/or greater than or equal to the second reference voltage, it is determined that the second voltage is not within a preset interval, and a low level signal is output to control the switch drive circuit to be blocked.

The present invention also provides a computer-readable storage medium on which a computer program is stored, characterized in that the program implements the above-mentioned drive protection method when executed by a processor.

By applying the technical solution of the present invention, the input first voltage is converted into the second voltage and the third voltage through the driving power supply; the operation circuit determines whether the second voltage is within the preset range according to the third voltage, and outputs a control signal according to the judgment result; the switch driving circuit controls itself to be turned on or off according to the control signal output by the operation circuit. Through the above solution, when the second voltage output by the driving power supply exceeds the preset range, the switch driving circuit can be controlled to be blocked, thereby keeping the power switch tube in the off state, avoiding the driving voltage being too high or too low, causing adverse effects on the power switch tube, and improving the stability and safety of the power switch tube.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a structural diagram of a driving protection circuit according to an embodiment of the present invention;

FIG2 is a structural diagram of a driving power supply according to an embodiment of the present invention;

FIG3 is a structural diagram of a computing circuit according to an embodiment of the present invention;

FIG4 is a structural diagram of a switch driving circuit according to an embodiment of the present invention;

FIG5 is a partial structural diagram of a driving protection circuit according to an embodiment of the present invention;

6 is a partial structural diagram of a driving protection circuit according to another embodiment of the present invention;

FIG. 7 is a flow chart of a drive protection method according to an embodiment of the present invention.

DETAILED DESCRIPTION

In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

It should be understood that the term "and/or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character "/" in this article generally indicates that the associated objects before and after are in an "or" relationship.

It should be understood that although the terms first, second, third, etc. may be used to describe resistors in embodiments of the present invention, these resistors should not be limited to these terms. These terms are only used to distinguish resistors arranged at different positions of the circuit. For example, without departing from the scope of embodiments of the present invention, a first resistor may also be referred to as a second resistor, and similarly, a second resistor may also be referred to as a first resistor.

As used herein, the words "if" and "if" may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

The optional embodiments of the present invention are described in detail below with reference to the accompanying drawings.

Example 1

The present embodiment provides a driving protection circuit. FIG1 is a structural diagram of a driving protection circuit according to an embodiment of the present invention. As shown in FIG1 , the driving protection circuit includes: a driving power supply 10, which is used to convert an input first voltage Vdc (for example, 24V) into a second voltage Vcc2 (for example, 15V) and a third voltage Vin (for example, 3V). The driving power supply 10 outputs the second voltage Vcc2 to the first input terminal of a switch driving circuit 30 through a first output terminal, so as to drive a power switch tube, and outputs the third voltage Vin to an operation circuit 20 through a second output terminal, wherein the third voltage Vin is proportional to the second voltage Vcc2, that is, the third voltage Vin is used to characterize the magnitude of the second voltage Vcc2. The larger the value of the third voltage Vin is, the larger the second voltage Vcc2 is, that is, the larger the driving voltage of the power switch tube Q is. In specific real time, the third voltage Vin can be obtained by dividing the second voltage Vcc2.

The operation circuit 20 has its input terminal connected to the driving power supply 10 and is used to determine whether the second voltage Vcc2 is within a preset range according to the third voltage Vin, and output a control signal Vout to the switch driving circuit 30 according to the determination result.

The second input terminal of the switch driving circuit 30 is connected to the operation circuit 20 , and is used to control itself to be turned on or off according to the control signal output by the operation circuit 20 .

When the second voltage Vcc2 exceeds a certain value, that is, the driving voltage of the power switch tube Q reaches above the upper limit, the value of the third voltage Vin will also rise to above the set upper limit, so that the operation circuit 20 outputs a control signal, and the control signal controls the switch drive circuit 30 to be blocked. When the switch drive circuit 30 is blocked, the power switch tube always remains in the off state; when the second voltage Vcc2 is lower than a certain value, that is, the driving voltage of the power switch tube Q is below the lower limit, the value of the third voltage Vin will also drop below the set lower limit, so that the operation circuit 20 outputs the same control signal to control the switch drive circuit 30 to be blocked, that is, the power switch tube always remains in the off state; when the second voltage Vcc2 is between the upper limit and the lower limit, the value of the third voltage Vin will also be between the set upper limit and the lower limit, so that the operation circuit 20 outputs another control signal to control the switch drive circuit 30 to be turned on. After the switch drive circuit 30 is turned on, the timing of turning on and off the power switch tube Q is controlled according to the PWM signal input by the switch drive circuit 30.

The driving protection circuit of this embodiment converts the input first voltage into the second voltage and the third voltage through the driving power supply, and the third voltage is proportional to the second voltage; the control signal is output according to the third voltage through the operation circuit; the switch driving circuit controls itself to open or close according to the control signal output by the operation circuit. Through the above scheme, when the second voltage output by the driving power supply exceeds the preset interval, the switch driving circuit can be controlled to close, thereby keeping the power switch tube in the off state, avoiding the driving voltage being too high or too low, causing adverse effects on the power switch tube, and improving the stability and safety of the power switch tube.

Example 2

This embodiment provides another driving protection circuit. FIG2 is a structural diagram of a driving power supply according to an embodiment of the present invention. As shown in FIG2 , the input side of the driving power supply 10 includes a first input terminal for receiving an input voltage Vdc, and also includes a ground terminal for connecting a reference ground GND, so that the input side forms a loop;

The input side of the driving power supply 10 includes a first output terminal for outputting a second voltage Vcc2 to the first input terminal of the switch driving circuit 30;

In order to realize the conversion of the input first voltage Vdc into the third voltage Vin, the first output end of the driving power supply 10 is also connected to the first end of the voltage divider circuit 101, the second end of the voltage divider circuit 101 is grounded, the output end of the voltage divider circuit 101 is the second output end of the driving power supply 10, and the second output end is connected to the input end of the operation circuit 20, which is used to output the third voltage Vin, that is, the output end of the voltage divider circuit 101 is the second output end of the driving power supply 10. Specifically, in order to realize the proportional reduction of the second voltage Vcc2, the voltage divider circuit 101 at least includes a first resistor R1 and a second resistor R2 arranged in series, and the line between the first resistor R1 and the second resistor R2 is connected to the input end of the operation circuit 20, and the size of the third voltage Vin is controlled by setting the ratio of the first resistor and the second resistor. In addition to the first output end and the second output end, the output side of the driving power supply 10 also includes a ground terminal to connect the reference ground GND so that the output side forms a loop.

FIG3 is a structural diagram of an operation circuit according to an embodiment of the present invention. In order to control the switch driving circuit 30 to be blocked when the driving voltage of the power switch tube Q reaches below the lower limit value to avoid the driving voltage being too low, as shown in FIG3, the operation circuit 20 includes: a first comparator U1, whose first input terminal is connected to the driving power supply 10 to receive the third voltage Vin, whose second input terminal inputs the first reference voltage Uref1, and whose output terminal is connected to the input terminal of the switch driving circuit 30; the first comparator U1 outputs a high level signal when the third voltage Vin is greater than the first reference voltage Uref1, and outputs a low level signal when the third voltage Vin is less than or equal to the first reference voltage Uref1. In this embodiment, the first input terminal of the first comparator U1 is a non-inverting input terminal, and the second input terminal is an inverting input terminal.

Similarly, in order to control the switch driving circuit 30 to be blocked when the driving voltage of the power switch tube Q is above the upper limit value to avoid the driving voltage being too high, as shown in FIG3 , the operation circuit 20 further includes a second comparator U2, whose first input terminal inputs the second reference voltage Uref2, whose second input terminal is connected to the driving power supply 10 to receive the third voltage Vin, and whose output terminal is connected to the input terminal of the switch driving circuit 30; the second comparator U2 outputs a high level signal when the third voltage Vin is less than the second reference voltage Uref2, and outputs a low level signal when the third voltage Vin is greater than or equal to the second reference voltage Uref2. In this embodiment, the first input terminal of the second comparator U2 is a non-inverting input terminal, and the second input terminal is an inverting input terminal.

After the first comparator U1 and the second comparator U2 output a high level or low level signal, it is necessary to output a control signal Vout according to the signal output by the first comparator U1 and the second comparator U2. Therefore, the above-mentioned operation circuit 20 also includes a third resistor R3, and the first end of the third resistor R3 inputs the initial voltage V ₀ , and the second end of the third resistor R3 is connected to the output end of the first comparator U1 and the second comparator U2. The third resistor R3 is used to divide the initial voltage V ₀ .

The above-mentioned first reference voltage Vref1 and second reference voltage Vref2 are determined according to the upper limit value and lower limit value of the second voltage Vcc2. For example, the first reference voltage Vref1 is the voltage value output after dividing the second voltage Vcc2 when the second voltage Vcc2 is the lower limit value, and the second reference voltage Vref2 is the voltage value output after dividing the second voltage Vcc2 when the second voltage Vcc2 is the upper limit value.

In this embodiment, only when the first comparator U1 and the second comparator U2 output high-level signals at the same time, the operation circuit 20 outputs a high-level signal, that is, the control signal Vout is a high-level signal, so as to control the switch driving circuit 30 to be blocked and opened; when one or both of the first comparator U1 and the second comparator U2 output low-level signals, the operation circuit 20 outputs a low-level signal, that is, the control signal Vout is a low-level signal, so as to control the switch driving circuit 30 to be blocked.

FIG4 is a structural diagram of a switch driving circuit according to an embodiment of the present invention. After receiving the control signal Vout, in order to realize the control of its own opening or blocking according to the control signal Vout, as shown in FIG4, the switch driving circuit 30 includes: a photocoupler OC, a first pin 1 of the photocoupler OC inputs a pulse width modulation PWM signal, a third pin 3 is grounded, a fifth pin 5 is connected to the output end of the operation circuit 20 to receive the control signal Vout, a sixth pin 6 is connected to the first output end of the driving power supply 10 to receive the second voltage Vcc2, and a seventh pin 7 is connected to the gate of the power switch tube to output a driving voltage to drive the power switch tube to turn on or off; wherein, the photocoupler OC is turned on when the control signal is a high-level signal, and then controls the timing of the power switch tube to turn on or off according to the PWM signal, and is blocked when the control signal is a low-level signal, so that the power switch tube is always kept in the off state. The second pin 2, the fourth pin 4 and the eighth pin 8 of the photocoupler OC are all grounded, and the pin 0 inputs the voltage Vcc1.

FIG5 is a partial structural diagram of a driving protection circuit according to an embodiment of the present invention. In a specific implementation, different driving resistances are required when controlling the power switch tube to be turned on and off. When controlling the power switch tube to be turned on, a smaller driving resistance is required, and when controlling the power switch tube to be turned off, a larger driving resistance is required. Based on the above considerations, as shown in FIG5 , the driving protection circuit further includes: a unidirectional conducting element D and a fourth resistor R4, which are arranged in series between the output end of the switch driving circuit 30 and the gate G of the power switch tube Q; and a fifth resistor R5, which is arranged in parallel at both ends of a series branch formed by the unidirectional conducting element D and the fourth resistor R4 being connected in series. In this embodiment, the unidirectional conducting element D is a diode, whose anode is connected to the output end of the switch driving circuit 30, and the cathode is connected to the fourth resistor R4. When the power switch tube is controlled to be turned on, the direction of the voltage drop is from the switch driving circuit 30 to the gate G of the power switch tube Q. At this time, the series branch where the unidirectional conducting element D is located is turned on, and the resistance value of the driving resistor is the total resistance value of the parallel circuit, which is relatively small. When the power switch tube is controlled to be turned off, the direction of the voltage drop is from the gate G of the power switch tube Q to the switch driving circuit 30. At this time, the series branch where the unidirectional conducting element D is located is not turned on, and the resistance value of the driving resistor is the resistance value of the fifth resistor R5, which is relatively large.

In order to suppress the resonant wave formed by the equivalent inductance and the equivalent capacitance of the gate path of the power switch tube, the above-mentioned drive protection circuit also includes: a capacitor C1 and a sixth resistor R6, and the above-mentioned capacitor C1 and the sixth resistor R6 are arranged in series between the gate G and the emitter E of the power switch tube Q, wherein the capacitance value of the capacitor C1 is not a constant, and its capacitance value changes with the current, voltage and temperature. In specific implementation, the capacitance value of the capacitor C1 and the resistance value of the sixth resistor R6 can be set through multiple tests to obtain the best resonant wave suppression effect.

Example 3

This embodiment provides another driving protection circuit. FIG6 is a partial structural diagram of a driving protection circuit according to another embodiment of the present invention. In the above-mentioned embodiment 2, the opening or blocking of the photoelectric coupler OC is controlled by the third voltage Vin. In order to realize the control of the power switch tube according to the third voltage Vin in another way, as shown in FIG6 , the above-mentioned driving protection circuit may also include: MCU40, the input end of MCU40 is connected to the operation circuit 20, and the output end thereof is connected to the switch driving circuit 30. MCU40 determines whether to block the PWM signal input by the switch driving circuit 30 according to the control signal Vout output by the operation circuit 20; wherein, after blocking the PWM signal input by the switch driving circuit 30, the power switch tube always remains in the off state.

Example 4

The present embodiment provides another driving protection circuit, which is described below in conjunction with FIGS. 2 to 5 . The structural diagram of the driving power supply is shown in FIG. 2 above. In specific implementation, the input 24V DC voltage (i.e., the first voltage Vdc) is reduced to about +15V (i.e., the second voltage Vcc2) through a transformer, and the voltage of about +15V is output to the sixth pin 6 of the driving photocoupler OC of the switch driving circuit shown in FIG. 5 . At the same time, the third voltage Vin is obtained by voltage division through the first resistor R1 and the second resistor R2, and the value of the collected third voltage Vin is transmitted to the operation circuit 20 for comparison operation and then outputs the control signal Vout.

The operation circuit 20 includes a first comparator U1 and a second comparator U2. The third voltage Vin is input to the non-inverting input terminal of the first comparator U1, and the first reference voltage Vref1 is input to the inverting input terminal. The second reference voltage Vref2 is input to the non-inverting input terminal of the second comparator U2, and the third voltage Vin is input to the inverting input terminal. The first reference voltage Vref1 is the voltage value output after the second voltage Vcc2 is divided when the second voltage Vcc2 is 14V, and the second reference voltage Vref2 is the voltage value output after the second voltage Vcc2 is divided when the second voltage Vcc2 is 17V. The first reference voltage Vref1 and the second reference voltage are generally between 0 and 3V. The value output by the operational amplifier is transmitted to the fifth pin 5 of the photocoupler OC. If the second voltage Vcc2 output by the driving power supply 10 is between +14V and +17V, the seventh pin 7 of the photocoupler OC outputs normally. If the output of the driving power supply 10 is not within this range, the photocoupler OC is blocked so that its seventh pin 7 no longer outputs a voltage signal.

The forward turn-on voltage of the power switch tube is generally +15V, which is more suitable. In order to prevent the device from being mis-turned on, the turn-off voltage is -5V. The fifth pin 5 of the photoelectric coupler OC involved in the present invention is turned on at a high level and blocked at a low level. This embodiment is explained by taking the turn-on voltage as an example: when the power of the driving power supply 1 is large enough, a voltage of about 15V is stably output. At this time, the control signal Vout output by the operation circuit 20 is at a high level, and the photoelectric coupler OC works normally. The input 24V DC voltage is converted into a second voltage Vcc2 of about +15V after being stepped down by the transformer and output to the fifth pin 5 of the driving photoelectric coupler. When the photoelectric coupler OC receives a high-level signal of the PWM signal sent by the main control unit (not shown in the figure), the photoelectric coupler outputs a 15V forward turn-on signal to the gate G of the power switch tube Q, driving the power switch tube Q to conduct; when the photoelectric coupler OC receives a low-level signal of the PWM signal sent by the main control, it outputs a -5V reverse turn-off signal to the gate G of the power switch tube Q, turning off the power switch tube Q. When the power of the driving power supply 10 is insufficient, resulting in an output voltage of 14V or less, the control signal Vout output by the operation circuit 20 is a low-level signal, the fifth pin 5 of the photocoupler OC is enabled, and the output side of the photocoupler OC is blocked. No matter whether the PWM signal received at the input side is a low-level signal or a high-level signal, the power switch tube Q cannot be driven to turn on. When the power of the driving power supply 10 is too high, resulting in an output voltage of 17V or more, the control signal Vout output by the operation circuit 20 is a low-level signal, the fifth pin 5 of the photocoupler OC is enabled, and the output side of the photocoupler OC is blocked. No matter whether the PWM signal received at the input side is a low-level signal or a high-level signal, the power switch tube Q cannot be driven to turn on.

In addition, as shown in FIG. 6 above, an MCU 40 may be provided between the operation circuit 20 and the switch drive circuit 30, and the control signal Vout output by the operation circuit 20 may be directly sent to the MCU 40. A logic judgment is performed through a software algorithm inside the MCU 40. When the control signal Vout is a high-level signal, the PWM signal issued by the main control unit is normally output to the switch drive circuit 30. When the control signal Vout is a low-level signal, the PWM signal issued by the main control unit is blocked. At the same time, the MCU 40 may also report a fault in which the drive voltage is too high or too low.

Example 5

This embodiment provides a drive protection method. FIG. 7 is a flow chart of the drive protection method according to an embodiment of the present invention. As shown in FIG. 7 , the method includes:

S101, converting an input first voltage into a second voltage and a third voltage and outputting the converted voltages, wherein the third voltage is proportional to the second voltage.

The third voltage is used to characterize the magnitude of the second voltage. The larger the value of the third voltage is, the larger the second voltage is, that is, the larger the driving voltage of the power switch tube is. In specific real time, the third voltage can be obtained by dividing the second voltage. For example, a voltage divider circuit is connected to the first terminal of the output end of the driving power supply. The voltage divider circuit includes at least a first resistor and a second resistor arranged in series. The line between the first resistor and the second resistor is connected to the input end of the operation circuit for outputting the third voltage. The magnitude of the third voltage is controlled by setting the ratio of the first resistor to the second resistor.

S102, judging whether the second voltage is within a preset interval according to the third voltage, and outputting a control signal according to the judgment result to control the switch driving circuit to be turned on or off; wherein the input end of the switch driving circuit also receives the second voltage to drive the power switch tube.

The control signal includes a high-level signal or a low-level signal. Through the operation circuit, a high-level signal or a low-level signal can be output according to the size of the driving voltage to control the switch drive circuit to be turned on or off. After the switch drive circuit is turned on, the timing of the power switch tube being turned on and off can be controlled according to the input PWM signal. After the switch drive circuit is blocked, the power switch tube always remains in the off state.

Through the driving protection method of this embodiment, the input first voltage is converted into a second voltage and a third voltage and then output, wherein the third voltage is proportional to the second voltage; a control signal is output according to the third voltage through an operation circuit; whether the second voltage is within a preset interval is judged according to the third voltage, and a control signal is output according to the judgment result to control the switch driving circuit to be turned on or blocked. This embodiment can control the switch driving circuit to be blocked when the second voltage output by the driving power source exceeds the preset interval, thereby keeping the power switch tube in the off state, avoiding the driving voltage being too high or too low, causing adverse effects on the power switch tube, and improving the stability and safety of the power switch tube.

In order to make the driving voltage of the power switch tube within a preset range, the above-mentioned step S102 includes: if the third voltage is greater than the first reference voltage and less than the second reference voltage, it is determined that the second voltage is within the preset range, and then a high-level signal is output to control the switch driving circuit to turn on; if the third voltage is less than or equal to the first reference voltage, and/or greater than or equal to the second reference voltage, it is determined that the second voltage is not within the preset range, and then a low-level signal is output to control the switch driving circuit to be blocked.

The above step S102 is implemented by an operation circuit. In order to avoid the driving voltage being too low, the operation circuit includes: a first comparator, whose first input terminal is connected to the second output terminal of the driving power supply to receive the third voltage, whose second input terminal inputs the first reference voltage, and whose output terminal is connected to the input terminal of the switch driving circuit; the first comparator outputs a high level signal when the third voltage is greater than the first reference voltage, and outputs a low level signal when the third voltage is less than or equal to the first reference voltage. The first input terminal of the first comparator is a non-inverting input terminal, and the second input terminal is an inverting input terminal.

Similarly, in order to avoid the driving voltage being too high, the operation circuit also includes a second comparator, whose first input terminal inputs the second reference voltage, whose second input terminal is connected to the second output terminal of the driving power supply to receive the third voltage, and whose output terminal is connected to the input terminal of the switch driving circuit; the second comparator U2 outputs a high level signal when the third voltage is less than the second reference voltage, and outputs a low level signal when the third voltage is greater than or equal to the second reference voltage. The first input terminal of the second comparator is a non-inverting input terminal, and the second input terminal is an inverting input terminal.

After the first comparator and the second comparator output a high level or a low level signal, a control signal is output according to the signals output by the first comparator and the second comparator. Specifically, the above-mentioned operation circuit also includes a third resistor, the first end of the third resistor is input with an initial voltage, the second end of the third resistor is connected to the output ends of the first comparator and the second comparator, and the third resistor is used to divide the initial voltage.

The above-mentioned first reference voltage and second reference voltage are determined according to the upper limit value and lower limit value of the second voltage. For example, the first reference voltage is the voltage value output after dividing the second voltage when the second voltage is the lower limit value, and the second reference voltage is the voltage value output after dividing the second voltage when the second voltage is the upper limit value.

In this embodiment, in order to ensure that the driving voltage is within a preset range, the operation circuit outputs a high-level signal only when the first comparator and the second comparator output high-level signals at the same time, that is, the control signal is a high-level signal, so as to control the switch driving circuit to be blocked and opened; when one or both of the first comparator and the second comparator output low-level signals, the operation circuit outputs a low-level signal, that is, the control signal is a low-level signal, so as to control the switch driving circuit to be blocked.

Example 6

This embodiment provides an electrical device, including a power switch tube, and the electrical device includes the driving protection circuit in the above embodiment, which is used to control the driving voltage of the power switch tube to ensure low power consumption and stable operation of the power switch tube. The electrical device includes at least one of the following: an air conditioner, a washing machine, a refrigerator, a water heater, a fan, a dryer, an air purifier, a water purifier, and a pure water machine.

Example 7

This embodiment provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the drive protection method in the above embodiment is implemented.

The circuit embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM/RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (13)

1. A driving protection circuit, characterized in that the driving protection circuit comprises: A driving power supply, used for converting an input first voltage into a second voltage and a third voltage, wherein the second voltage is output to a first input terminal of a switch driving circuit for driving a power switch tube; and the third voltage is output to an operation circuit; The operation circuit is used to determine whether the second voltage is within a preset range according to the third voltage, and output a control signal according to the determination result; The switch driving circuit, whose second input terminal is connected to the operation circuit, is used to control itself to be turned on or off according to the control signal; the switch driving circuit includes: A photocoupler, wherein a first terminal thereof inputs a pulse width modulation (PWM) signal, a second terminal thereof is grounded, a third terminal thereof is connected to the operation circuit to receive the control signal, a fourth terminal thereof is connected to the driving power supply to receive the second voltage, and a fifth terminal thereof is connected to the gate of the power switch tube; wherein the photocoupler is turned on when the control signal is a high-level signal, controls the on-off timing of the power switch tube according to the PWM signal, and is blocked when the control signal is a low-level signal, so that the power switch tube is always kept in an off state. 2. The driving protection circuit according to claim 1, characterized in that: The first output terminal of the driving power supply is connected to the first input terminal of the switch driving circuit; The first output end of the driving power supply is also connected to the first end of the voltage divider circuit, the second end of the voltage divider circuit is grounded, the output end of the voltage divider circuit is the second output end of the driving power supply, and the second output end is connected to the input end of the operation circuit for outputting the third voltage to the operation circuit. 3. The driving protection circuit according to claim 2 is characterized in that the voltage divider circuit comprises at least a first resistor and a second resistor connected in series, and a line between the first resistor and the second resistor is connected to an input end of the operation circuit. 4. The driving protection circuit according to claim 1, wherein the operation circuit comprises: a first comparator, wherein a first input terminal of the comparator is connected to the driving power supply to receive the third voltage, a second input terminal of the comparator is input with the first reference voltage, and an output terminal of the comparator is connected with the input terminal of the switch driving circuit; the first comparator is used to output a high level signal when the third voltage is greater than the first reference voltage, and output a low level signal when the third voltage is less than or equal to the first reference voltage; a second comparator, wherein a first input terminal of the second comparator inputs a second reference voltage, a second input terminal of the second comparator is connected to the driving power supply to receive the third voltage, and an output terminal of the second comparator is connected to an input terminal of the switch driving circuit; the second comparator is used to output a high level signal when the third voltage is less than the second reference voltage, and output a low level signal when the third voltage is greater than or equal to the second reference voltage; A third resistor has a first end thereof input with an initial voltage, and a second end thereof connected to output ends of the first comparator and the second comparator, and is used for dividing the initial voltage. 5. The driving protection circuit according to claim 4 is characterized in that the operation circuit is specifically used to: output a high level signal when the first comparator and the second comparator output high level signals at the same time; output a low level signal when at least one of the first comparator and the second comparator outputs a low level signal. 6. The driving protection circuit according to claim 1, characterized in that the driving protection circuit further comprises: A microcontroller unit MCU, whose input end is connected to the operation circuit and whose output end is connected to the switch drive circuit, is used to determine whether to block the PWM signal input by the switch drive circuit according to the control signal output by the operation circuit; wherein, when the PWM signal input by the switch drive circuit is blocked, the power switch tube always remains in the off state. 7. The driving protection circuit according to claim 1, characterized in that the driving protection circuit further comprises: a unidirectional conductive element and a fourth resistor, wherein the unidirectional conductive element and the fourth resistor are arranged in series between the output end of the switch driving circuit and the gate of the power switch tube; The fifth resistor is arranged in parallel at two ends of a series branch formed by the unidirectional conductive element and the fourth resistor. 8. The driving protection circuit according to claim 1, characterized in that the driving protection circuit further comprises: A capacitor and a sixth resistor, wherein the capacitor and the sixth resistor are arranged in series between the gate and the emitter of the power switch tube. 9. An electrical device, comprising a power switch tube, characterized in that the electrical device comprises the driving protection circuit according to any one of claims 1 to 8. 10. The electrical device according to claim 9, characterized in that the electrical device comprises at least one of the following: Air conditioners, washing machines, refrigerators, water heaters, fans, dryers, air purifiers, water purifiers, and water purifiers. 11. A driving protection method, applied to the driving protection circuit according to any one of claims 1 to 8, characterized in that the method comprises: Converting the input first voltage into a second voltage and a third voltage and then outputting the converted voltage; Determine whether the second voltage is within a preset range based on the third voltage, and output a control signal based on the determination result to control the switch drive circuit to be turned on or off; wherein the input end of the switch drive circuit also receives the second voltage to drive the power switch tube. 12. The method according to claim 11, characterized in that judging whether the second voltage is within a preset interval according to the third voltage, and outputting a control signal according to the judging result to control the switch driving circuit to be turned on or off, comprises: If the third voltage is greater than the first reference voltage and less than the second reference voltage, it is determined that the second voltage is within a preset range, and a high level signal is output to control the switch driving circuit to turn on; If the third voltage is less than or equal to the first reference voltage, and/or greater than or equal to the second reference voltage, it is determined that the second voltage is not within a preset interval, and a low level signal is output to control the switch drive circuit to be blocked. 13. A computer-readable storage medium having a computer program stored thereon, wherein when the program is executed by a processor, the method according to claim 11 or 12 is implemented.