阅读说明：本技术 一种驱动保护电路、方法及电器设备 (Drive protection circuit and method and electrical equipment ) 是由 冯上贤 黄猛 王京 孙一嘉 崔铖浩 杜斌 于 2020-10-22 设计创作，主要内容包括：本发明公开一种驱动保护电路、方法及电器设备。其中,该电路包括：驱动电源,用于将输入的第一电压转换为第二电压和第三电压,第二电压输出至开关驱动电路,用于驱动功率开关管；第三电压输出至运算电路；运算电路,用于根据第三电压判断第二电压是否在预设区间内,并根据判断结果输出控制信号；开关驱动电路,其输入端连接所述运算电路,用于根据控制信号控制自身开启或者封锁。通过本发明,能够避免驱动电压过高或者过低,对功率开关管造成不利影响,提高功率开关管的稳定性和安全性。(The invention discloses a drive protection circuit, a drive protection method and electrical equipment. Wherein, this circuit includes: the driving power supply is used for converting the input first voltage into a second voltage and a third voltage, and the second voltage is output to the switch driving circuit and used for driving the power switch tube; the third voltage is output to the arithmetic circuit; the operation circuit is used for judging whether the second voltage is in a preset interval according to the third voltage and outputting a control signal according to a judgment result; and the input end of the switch driving circuit is connected with the operation circuit and is used for controlling the self to be opened or closed according to the control signal. According to the invention, the adverse effect on the power switch tube caused by overhigh or overlow driving voltage can be avoided, and the stability and the safety of the power switch tube are improved.)

1. A drive protection circuit, comprising:

the driving power supply is used for converting the input first voltage into a second voltage and a third voltage, and the second voltage is output to the first input end of the switch driving circuit and used for driving the power switch tube; the third voltage is output to an arithmetic circuit;

the operation circuit is used for judging whether the second voltage is in a preset interval according to the third voltage and outputting a control signal according to a judgment result;

and the second input end of the switch driving circuit is connected with the arithmetic circuit and is used for controlling the switch driving circuit to be opened or closed according to the control signal.

2. The drive protection circuit of claim 1,

the first output end of the driving power supply is connected with the first input end of the switch driving circuit;

the first output end of the driving power supply is further connected with the first end of the voltage division circuit, the second end of the voltage division circuit is grounded, the output end of the voltage division circuit is the second output end of the driving power supply, and the second output end is connected with the input end of the operational circuit and used for outputting the third voltage to the operational circuit.

3. The driving protection circuit according to claim 2, wherein 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 the input terminal of the arithmetic circuit.

4. The drive protection circuit according to claim 1, wherein the arithmetic circuit comprises:

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

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

and a third resistor, a first end of which inputs an initial voltage, and a second end of which is connected to the output ends of the first comparator and the second comparator, and is used for dividing the initial voltage.

5. The drive protection circuit according to claim 4, wherein the arithmetic circuit is specifically configured to: outputting a high level signal when the first comparator and the second comparator output the high level signal at the same time; and outputting a low level signal when at least one of the first comparator and the second comparator outputs the low level signal.

6. The drive protection circuit according to claim 1, wherein the switch drive circuit comprises:

a photoelectric coupler, a first terminal of which inputs a Pulse Width Modulation (PWM) signal, a second terminal of which is grounded, a third terminal of which is connected with the arithmetic circuit to receive the control signal, a fourth terminal of which is connected with the driving power supply to receive the second voltage, and a fifth terminal of which is connected with a gate pole of the power switch tube; the photoelectric coupler is started when the control signal is a high-level signal, controls the on-off time 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.

7. The driving protection circuit according to claim 1, further comprising:

the input end of the MCU is connected with the arithmetic circuit, and the output end of the MCU is connected with the switch driving circuit and used for determining whether to block the PWM signal input by the switch driving circuit according to the control signal output by the arithmetic circuit; when the PWM signal input by the switch driving circuit is blocked, the power switch tube is always kept in an off state.

8. The driving protection circuit according to claim 1, further comprising:

the unidirectional conducting element and the fourth resistor are arranged between the output end of the switch driving circuit and the gate pole of the power switch tube in series;

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

9. The driving protection circuit according to claim 1, further comprising:

and the capacitor and the sixth resistor are arranged between the gate electrode and the emitter of the power switch tube in series.

10. An electrical apparatus comprising a power switch tube, characterized in that the drive protection circuit of any one of claims 1 to 9 is included in the electrical apparatus.

11. The electrical device of claim 19, wherein the electrical device comprises at least one of:

air conditioner, washing machine, refrigerator, water heater, fan, drying-machine, air purifier, water purification machine.

12. A drive protection method applied to the drive protection circuit according to any one of claims 1 to 9, the method comprising:

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

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

13. The method of claim 12, wherein determining whether the second voltage is within a predetermined interval according to the third voltage, and outputting a control signal to control a switch driving circuit to be turned on or off according to the determination result comprises:

if the third voltage is greater than the first reference voltage and less than a second reference voltage, determining that the second voltage is within a preset interval, and further outputting a high level signal to control the switch driving circuit to be switched on;

and 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, judging that the second voltage is not in a preset interval, and further outputting a low-level signal to control the switch driving circuit to block.

14. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the method according to claim 12 or 13.

Technical Field

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

Background

A driving protection circuit of a power switch tube (e.g., an Insulated Gate Bipolar Transistor, IGBT) is a key for ensuring stable operation of the power switch tube, and if the power switch tube is driven badly, not only the service life of the power device is damaged, but also the whole system is broken down.

When the power switch tube is switched on, the driving circuit needs to provide a forward voltage with a certain amplitude, which is enough to fully saturate the IGBT. Theoretically, the switch-on state can be conducted as long as the forward voltage VGE > the forward voltage threshold VGEth, the higher the forward driving voltage is, the lower the saturation voltage drop VCEsat of the power switch tube is, and the lower the on-state loss is, but if the gate is too high, the short-circuit current of the device is larger, the short-circuit duration is shortened, the power loss is larger, and the reverse recovery overvoltage of the freewheeling diode is increased. The driving voltage is low, the power switch tube is not fully saturated, the power switch tube works in a linear active area, the current and the voltage are very large, the dissipation power is overlarge, and the temperature is saved and the tube is exploded or burnt. Therefore, the power switch tube is adversely affected by the excessively high or excessively low driving voltage.

Aiming at the problem that the driving voltage is too high or too low in the prior art, and the power switch tube is adversely affected, an effective solution is not provided at present.

Disclosure of Invention

The embodiment of the invention provides a driving protection circuit, a driving protection method and electrical equipment, and aims to solve the problem that in the prior art, a power switch tube is adversely affected due to overhigh or overlow driving voltage.

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

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

the second voltage is output to a first input end of the switch driving circuit and is used for driving the power switch tube; the third voltage is output to an arithmetic circuit;

the operation circuit is used for judging whether the second voltage is in a preset interval according to the third voltage and outputting a control signal according to a judgment result;

and the second input end of the switch driving circuit is connected with the arithmetic circuit and is used for controlling the switch driving circuit to be opened or closed according to the control signal.

Furthermore, the first output end of the driving power supply is connected with the first input end of the switch driving circuit, the first output end of the driving power supply is further connected with the first end of the voltage division circuit, the second end of the voltage division circuit is grounded, the output end of the voltage division circuit is the second output end of the driving power supply, and the second output end is connected with the input end of the operational circuit and used for outputting the third voltage to the operational circuit.

Furthermore, the voltage division circuit at least comprises 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 with the input end of the operation circuit.

Further, the arithmetic circuit includes:

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

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

and a third resistor, a first end of which inputs an initial voltage, and a second end of which is connected to the output ends of the first comparator and the second comparator, and is used for dividing the initial voltage.

Further, the arithmetic circuit is specifically configured to: outputting a high level signal when the first comparator and the second comparator output the high level signal at the same time; and outputting a low level signal when at least one of the first comparator and the second comparator outputs the low level signal.

Further, the switch driving circuit includes:

a photoelectric coupler, a first terminal of which inputs a Pulse Width Modulation (PWM) signal, a second terminal of which is grounded, a third terminal of which is connected with the arithmetic circuit to receive the control signal, a fourth terminal of which is connected with the driving power supply to receive the second voltage, and a fifth terminal of which is connected with a gate pole of the power switch tube; the photoelectric coupler is started when the control signal is a high-level signal, controls the on-off time 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.

Further, the drive protection circuit further includes:

the input end of the MCU is connected with the arithmetic circuit, and the output end of the MCU is connected with the switch driving circuit and used for determining whether to block the PWM signal input by the switch driving circuit according to the control signal output by the arithmetic circuit; when the PWM signal input by the switch driving circuit is blocked, the power switch tube is always kept in an off state.

Further, the drive protection circuit further includes:

the unidirectional conducting element and the fourth resistor are arranged between the output end of the switch driving circuit and the gate pole of the power switch tube in series;

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

Further, the drive protection circuit further includes:

and the capacitor and the sixth resistor are arranged between the gate electrode and the emitter of the power switch tube in series.

The invention also provides electrical equipment which comprises the power switch tube and comprises the drive protection circuit.

Further, the electrical device comprises at least one of: air conditioner, washing machine, refrigerator, water heater, fan, drying-machine, air purifier, water purification machine.

The present invention also provides a drive protection method applied to the drive protection circuit according to any one of claims 1 to 9, characterized in that the method includes:

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

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

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

if the third voltage is greater than the first reference voltage and less than a second reference voltage, determining that the second voltage is within a preset interval, and further outputting a high level signal to control the switch driving circuit to be switched on;

and 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, judging that the second voltage is not in a preset interval, and further outputting a low-level signal to control the switch driving circuit to block.

The present invention also provides a computer-readable storage medium having stored thereon a computer program characterized in that the program realizes the above-described drive protection method when executed by a processor.

By applying the technical scheme of the invention, the input first voltage is converted into the second voltage and the third voltage through the driving power supply; judging whether the second voltage is in a preset interval or not according to the third voltage through an arithmetic circuit, and outputting a control signal according to a judgment result; the switch driving circuit controls the self to be opened or closed according to the control signal output by the operation circuit. Through above-mentioned scheme, can surpass when predetermineeing the interval at drive power supply output's second voltage, control switch drive circuit blockade, and then make power switch tube keep the off-state, avoid drive voltage too high or low excessively, cause adverse effect to power switch tube, improve power switch tube's stability and security.

Drawings

Fig. 1 is a structural diagram of a drive protection circuit according to an embodiment of the present invention;

fig. 2 is a structural diagram of a driving power supply according to an embodiment of the present invention;

FIG. 3 is a block diagram of an arithmetic circuit according to an embodiment of the present invention;

FIG. 4 is a block diagram of a switch driver circuit according to an embodiment of the present invention;

FIG. 5 is a block diagram of a portion of a drive protection circuit according to an embodiment of the present invention;

fig. 6 is a partial block diagram of a drive protection circuit according to another embodiment of the present invention;

fig. 7 is a flowchart of a drive protection method according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, and "a plurality" typically includes at least two.

It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

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

The words "if", as used herein, may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrases "if determined" or "if detected (a stated condition or event)" may be interpreted as "when determined" or "in response to a determination" or "when detected (a stated condition or event)" or "in response to a detection (a stated condition or event)", depending on the context.

It is also noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in the article or device in which the element is included.

Alternative 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, and fig. 1 is a structural diagram of the driving protection circuit according to the embodiment of the present invention, as shown in fig. 1, the driving protection circuit includes: the driving power supply 10 is configured to convert an input first voltage Vdc (e.g. 24V) into a second voltage Vcc2 (e.g. 15V) and a third voltage Vin (e.g. 3V), the driving power supply 10 outputs the second voltage Vcc2 to a first input terminal of the switch driving circuit 30 through a first output terminal for driving the power switch tube, and outputs the third voltage Vin to the 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 represent the magnitude of the second voltage Vcc2, and the larger the value of the third voltage Vin, the larger the second voltage Vcc2, that is, the larger the driving voltage of the power switch tube Q, the third voltage Vin can be obtained after being divided by the second voltage Vcc2 in real time.

The input end of the arithmetic circuit 20 is connected to the driving power supply 10, and is configured to determine whether the second voltage Vcc2 is within a preset interval according to the third voltage Vin, and output the 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 arithmetic circuit 20, and is used for controlling the on/off of the switch driving circuit according to the control signal output by the arithmetic circuit 20.

When the second voltage Vcc2 exceeds a certain value, that is, the driving voltage of the power switch tube Q reaches an upper limit value or more, the value of the third voltage Vin also rises to a value above the set upper limit value, so that the arithmetic circuit 20 outputs a control signal which controls the switch driving circuit 30 to block, and the power switch tube is always kept in an off state in the blocking state of the switch driving circuit 30; when the second voltage Vcc2 is lower than a certain value, that is, the driving voltage of the power switch Q is lower than the lower limit value, the value of the third voltage Vin also drops below the set lower limit value, so that the arithmetic circuit 20 outputs the same control signal to control the switch driving circuit 30 to be locked, that is, the power switch Q is always kept in the off state; when the second voltage Vcc2 is between the upper limit value and the lower limit value, the value of the third voltage Vin is also between the upper limit value and the lower limit value, so that the operation circuit 20 outputs another control signal to control the switch driving circuit 30 to be turned on, and after the switch driving circuit 30 is turned on, the timing of turning on and off the power switch Q is controlled according to the PWM signal input by the switch driving circuit 30.

In the driving protection circuit of the embodiment, the input first voltage is converted into a second voltage and a third voltage through the driving power supply, and the third voltage is in direct proportion to the second voltage; outputting a control signal according to the third voltage through an arithmetic circuit; the switch driving circuit controls the self to be opened or closed according to the control signal output by the operation circuit. Through above-mentioned scheme, can surpass when predetermineeing the interval at drive power supply output's second voltage, control switch drive circuit blockade, and then make power switch tube keep the off-state, avoid drive voltage too high or low excessively, cause adverse effect to power switch tube, improve power switch tube's stability and security.

Example 2

In this embodiment, another driving protection circuit is provided, and fig. 2 is a structural diagram of a driving power supply according to an embodiment of the present invention, as shown in fig. 2, an input side of the driving power supply 10 includes a first input terminal for receiving an input voltage Vdc, and further includes a ground terminal for connecting to a ground reference 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 convert the input first voltage Vdc into the third voltage Vin, the first output terminal of the driving power supply 10 is further connected to the first terminal of the voltage dividing circuit 101, the second terminal of the voltage dividing circuit 101 is grounded, the output terminal of the voltage dividing circuit 101 is the second output terminal of the driving power supply 10, and the second output terminal is connected to the input terminal of the operation circuit 20, so as to output the third voltage Vin, that is, the output terminal of the voltage dividing circuit 101 is the second output terminal of the driving power supply 10. Specifically, in order to achieve the scaling down of the second voltage Vcc2, the voltage dividing circuit 101 includes at least a first resistor R1 and a second resistor R2 connected in series, a line between the first resistor R1 and the second resistor R2 is connected to the input terminal of the arithmetic circuit 20, and the magnitude of the third voltage Vin is controlled by setting the ratio of the first resistor to the second resistor. The output side of the driving power supply 10 includes a ground terminal in addition to the first output terminal and the second output terminal to connect to the ground GND so that the output side forms a loop.

Fig. 3 is a structural diagram of an arithmetic circuit according to an embodiment of the present invention, in order to control the switch driving circuit 30 to block when the driving voltage of the power switch Q reaches a lower limit value or less, as shown in fig. 3, the arithmetic circuit 20 includes: a first comparator U1, a first input terminal of which is connected to the driving power supply 10 to receive the third voltage Vin, a second input terminal of which is input with the first reference voltage Uref1, and an output terminal of which 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 Uref 1. 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 block when the driving voltage of the power switch Q is above the upper limit value, so as to avoid the driving voltage from being too high, as shown in fig. 3, the arithmetic circuit 20 further includes a second comparator U2, a first input terminal of which inputs a second reference voltage Uref2, a second input terminal of which is connected to the driving power supply 10 to receive a third voltage Vin, and an output terminal of which 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 Uref 2. 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.

Since the control signal Vout needs to be output according to the signals output by the first comparator U1 and the second comparator U2 after the first comparator U1 and the second comparator U2 output the high level or the low level signals, the arithmetic circuit 20 further includes a third resistor R3, and the first end of the third resistor R3 inputs the initial voltage V3₀A second terminal of the third resistor is connected to the output terminals of the first comparator U1 and the second comparator U2, and a third resistor R3 is used for comparing the initial voltage V₀Partial pressure is carried out.

The first reference voltage Vref1 and the second reference voltage Vref2 are determined based on the upper limit value and the lower limit value of the second voltage Vcc2, and for example, when the first reference voltage Vref1 is the lower limit value of the second voltage Vcc2, the first reference voltage Vref 3538 is a voltage value of an output obtained by dividing the second voltage Vcc2, and when the second reference voltage Vref2 is the upper limit value of the second voltage Vcc2, the second reference voltage Vcc2 is a voltage value of an output obtained by dividing the second voltage Vcc 2.

In the 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 turned on and off; when one or both of the first comparator U1 and the second comparator U2 outputs a low level signal, the operation circuit 20 outputs a low level signal, i.e., the control signal Vout is a low level signal, so as to control the switch driving circuit 30 to block.

Fig. 4 is a structural diagram of a switch driving circuit according to an embodiment of the present invention, and in order to control the on or off of the switch driving circuit according to a control signal Vout after receiving the control signal Vout, as shown in fig. 4, the switch driving circuit 30 includes: the photoelectric coupler OC is characterized in that a first pin 1 of the photoelectric coupler OC inputs a Pulse Width Modulation (PWM) signal, a third pin 3 of the photoelectric coupler OC is grounded, a fifth pin 5 of the photoelectric coupler OC is connected with the output end of the arithmetic circuit 20 to receive a control signal Vout, a sixth pin 6 of the photoelectric coupler OC is connected with the first output end of the driving power supply 10 to receive a second voltage Vcc2, and a seventh pin 7 of the photoelectric coupler OC is connected with a gate pole of a power switching tube to output a driving voltage to drive the power switching tube to be switched on or switched off; the photoelectric coupler OC is started when the control signal is a high level signal, then the on-off time of the power switch tube is controlled according to the PWM signal, and the on-off time of the power switch tube is blocked when the control signal is a low level signal, so that the power switch tube is always kept in an off state. The second pin 2, the fourth pin 4 and the eighth pin 8 of the optocoupler OC are all grounded, and the pin 0 inputs the voltage Vcc 1.

Fig. 5 is a partial structural diagram of a driving protection circuit according to an embodiment of the present invention, in a specific implementation, when a power switching tube is controlled to be turned on and off, a required driving resistance is different, when the power switching tube is controlled to be turned on, the required driving resistance is smaller, and when the power switching tube is controlled to be turned off, the required driving resistance is larger, and based on the above consideration, as shown in fig. 5, the driving protection circuit further includes: the unidirectional conducting element D and the fourth resistor R4 are arranged between the output end of the switch driving circuit 30 and the gate G of the power switch tube Q in series; the fifth resistor R5 is connected in parallel to two ends of a series branch formed by the unidirectional conducting device D and the fourth resistor R4 connected in series. In this embodiment, the unidirectional conducting element D is a diode, an anode of the diode is connected to the output terminal of the switch driving circuit 30, a cathode of the diode is connected to the fourth resistor R4, when the power switching tube is controlled to be turned on, a voltage drop direction is from the switch driving circuit 30 to the gate G of the power switching tube Q, at this time, the serial branch where the unidirectional conducting element D is located is turned on, a resistance value of the driving resistor is a total resistance value of the parallel circuit, the resistance value is smaller, when the power switching tube is controlled to be turned off, the voltage drop direction is from the gate G of the power switching tube Q to the switch driving circuit 30, at this time, the serial branch where the unidirectional conducting element D is located is not turned on, and a resistance value of the driving resistor is a resistance value of the fifth resistor R5.

In order to suppress the resonant wave formed by the equivalent inductance of the gate path and the equivalent capacitance of the gate path of the power switch tube, the driving protection circuit further comprises: the capacitor C1 and the sixth resistor R6 are connected in series, and the capacitor C1 and the sixth resistor R6 are connected in series between the gate G and the emitter E of the power switching tube Q, wherein the capacitance value of the capacitor C1 is not constant, and the capacitance value varies with current, voltage and temperature, and 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, so that the optimal resonance wave suppression effect is obtained.

Example 3

In this embodiment, another driving protection circuit is provided, fig. 6 is a partial structural diagram of a driving protection circuit according to another embodiment of the present invention, in the above embodiment 2, the photocoupler OC is controlled to be turned on or turned off by the third voltage Vin, and in order to implement control of the power switch tube according to the third voltage Vin in another way, as shown in fig. 6, the driving protection circuit may further include: the input end of the MCU40 is connected with the arithmetic circuit 20, the output end of the MCU40 is connected with the switch driving circuit 30, and the MCU40 determines whether to block the PWM signal input by the switch driving circuit 30 according to a control signal Vout output by the arithmetic circuit 20; after the PWM signal inputted from the blocking switch driving circuit 30, the power switch tube is always kept in an off state.

Example 4

In the present embodiment, another driving protection circuit is provided, and the structure diagram of the driving power supply is as shown in fig. 2, and in the 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 the transformer, the voltage about +15V is output to the sixth pin 6 of the driving photocoupler OC of the switching driving circuit shown in fig. 5, meanwhile, the voltage is divided by the first resistor R1 and the second resistor R2 to obtain the third voltage Vin, and the collected value of the third voltage Vin is transmitted to the operation circuit 20 for comparison operation, so as to output the control signal Vout.

The operation circuit 20 includes a first comparator U1 and a second comparator U2, wherein a non-inverting input terminal of the first comparator U1 inputs a third voltage Vin, an inverting input terminal thereof inputs a first reference voltage Vref1, a non-inverting input terminal of the second comparator U2 inputs a second reference voltage Vref2, and an inverting input terminal thereof inputs the third voltage Vin, wherein the first reference voltage Vref1 is a voltage value of an output obtained by dividing the second voltage Vcc2 when the second voltage Vcc2 is 14V, the second reference voltage Vref2 is a voltage value obtained by dividing the second voltage Vcc2 when the second voltage Vcc2 is 17V, the first reference voltage Vref1 and the second reference voltage are generally between 0V and 3V, the output value is transmitted to a fifth pin 5 of the photocoupler OC through an operational amplifier, and if the second voltage 2 output from the driving power supply 10 is between +14V +17V, the seventh pin 7 of the photocoupler outputs a normal driving power supply 10 if the output is not within a range of Vcc +17V, the opto-coupler 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 proper to be +15V, and-5V is selected as the turn-off voltage to prevent the device from being conducted by mistake, the fifth pin 5 of the photoelectric coupler OC related to the invention is opened at a high level and blocked at a low level, and the embodiment takes the turn-on voltage as an example for explanation: when the power of the driving power supply 1 is large enough, a voltage of about 15V is stably output, and at this time, the control signal Vout output by the operation circuit 20 is at a high level, and the photocoupler OC normally operates. The input 24V direct current voltage is converted into a second voltage Vcc2 of about +15V after being reduced by a transformer and then is output to a fifth pin 5 of a driving photoelectric coupler, when the photoelectric coupler OC receives a high-level signal of a PWM signal sent by a main control unit (not shown in the figure), the photoelectric coupler outputs a 15V forward opening signal to a gate pole G of a power switch tube Q, and the power switch tube Q is driven to be conducted; when the photoelectric coupler OC receives a low-level signal of a PWM signal sent by the master controller, a-5V reverse turn-off signal is output to a gate pole G of the power switch tube Q, and the power switch tube Q is turned off. When the power of the driving power supply 10 is insufficient and the output voltage is 14V or less, the control signal Vout output by the operation circuit 20 is a low level signal, the fifth pin 5 of the photoelectric coupler OC is enabled, the output side of the photoelectric coupler OC is blocked, and the power switching tube Q cannot be driven to be turned on no matter whether the PWM signal received by the input side is a low level signal or a high level signal. When the power of the driving power supply 10 is too high, which results 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 photoelectric coupler OC is enabled, the output side of the photoelectric coupler OC is blocked, and the power switching tube Q cannot be driven to be turned on no matter the PWM signal received by the input side is a low level signal or a high level signal.

In addition, as shown in fig. 6, an MCU40 may be disposed between the operation circuit 20 and the switch driving circuit 30, the control signal Vout output by the operation circuit 20 is directly sent to the MCU40, and a logic determination is performed through a software algorithm inside the MCU40, when the control signal Vout is a high level signal, the PWM signal sent by the main control unit is normally output to the switch driving circuit 30, and when the control signal Vout is a low level signal, the PWM signal sent by the main control unit is blocked, and at the same time, the MCU40 may report a fault that the driving voltage is too high or too low.

Example 5

The present embodiment provides a driving protection method, and fig. 7 is a flowchart of the driving protection method according to the embodiment of the present invention, as shown in fig. 7, the method includes:

s101, converting the input first voltage into a second voltage and a third voltage and then outputting the second voltage and the third voltage, wherein the third voltage is in direct proportion to the second voltage.

The third voltage is used for representing 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 switching tube is, in concrete real time, the third voltage can be obtained by dividing the second voltage, for example, the first terminal of the output end of the driving power supply is connected with a voltage dividing circuit, the voltage dividing circuit at least comprises a first resistor and a second resistor which are arranged in series, a line between the first resistor and the second resistor is connected with the input end of the operational circuit and is used for outputting the third voltage, and the magnitude of the third voltage is controlled by setting the proportion of the first resistor and the second resistor.

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

The control signal comprises a high level signal or a low level signal, the high level signal or the low level signal can be output through the operation circuit according to the magnitude of the driving voltage so as to control the switch driving circuit to be started or blocked, after the switch driving circuit is started, the on-off time of the power switch tube can be controlled according to the input PWM signal, and after the switch driving circuit is blocked, the power switch tube is always kept in an off state.

By the driving protection method of the embodiment, the input first voltage is converted into a second voltage and a third voltage and then output, wherein the third voltage is in direct proportion to the second voltage; outputting a control signal according to the third voltage through an arithmetic circuit; and judging whether the second voltage is in a preset interval according to the third voltage, and outputting a control signal according to a judgment result so as to control the switch driving circuit to be started or blocked. This embodiment can surpass when predetermineeing the interval at drive power supply output's second voltage, and control switch drive circuit blockades, and then makes power switch tube keep the off-state, avoids drive voltage too high or low excessively, causes adverse effect to power switch tube, improves power switch tube's stability and security.

In order to make the driving voltage of the power switch tube within the preset interval, the step S102 includes: if the third voltage is greater than the first reference voltage and less than a second reference voltage, determining that the second voltage is within a preset interval, and further outputting a high level signal to control the switch driving circuit to be switched on; and 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, judging that the second voltage is not in a preset interval, and further outputting a low-level signal to control the switch driving circuit to block.

The step S102 is implemented by an arithmetic circuit, which includes: a first comparator, a first input end of which is connected with a second output end of the driving power supply to receive a third voltage, a second input end of which inputs a first reference voltage, and an output end of which is connected with an input end 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 end of the first comparator is a non-inverting input end, and the second input end of the first comparator is an inverting input end.

Similarly, in order to avoid the driving voltage from being too high, the arithmetic circuit further comprises a second comparator, a first input end of which inputs a second reference voltage, a second input end of which is connected with a second output end of the driving power supply to receive a third voltage, and an output end of which is connected with the input end 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 end of the second comparator is a non-inverting input end, and the second input end of the second comparator is an inverting input end.

After the first comparator and the second comparator output high-level or low-level signals, the control signal is output according to the signals output by the first comparator and the second comparator, specifically, the arithmetic circuit further includes a third resistor, an initial voltage is input to a first end of the third resistor, a second end of the third resistor is connected to output ends of the first comparator and the second comparator, and the third resistor is used for dividing the initial voltage.

The first reference voltage and the second reference voltage are determined according to an upper limit value and a lower limit value of the second voltage, for example, when the first reference voltage is the lower limit value of the second voltage, the first reference voltage is an output voltage value obtained by dividing the second voltage, and when the second reference voltage is the upper limit value of the second voltage, the second reference voltage is an output voltage value obtained by dividing the second voltage.

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

Example 6

The embodiment provides an electrical apparatus, which includes a power switch tube, and the electrical apparatus includes the driving protection circuit in the above embodiment, and is used to control the driving voltage of the power switch tube, so as to ensure that the power switch tube has low consumption and operates stably. The electrical equipment at least comprises one of the following components: air conditioner, washing machine, refrigerator, water heater, fan, drying-machine, air purifier, water purification machine.

Example 7

The present embodiment provides a computer-readable storage medium on which a computer program is stored, which, when executed by a processor, implements the drive protection method in the above-described embodiments.

The above-described circuit embodiments are only illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.

Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.