CN115800188A - Power switch device protection circuit, control circuit of power module and power module - Google Patents

Abstract

The utility model provides a power switch device protection circuit, power module's control circuit and power module, wherein the protection circuit includes: PWM generating circuit, sampling circuit, amplifier circuit and power switching device switch regulating circuit, wherein: the sampling circuit is used for inputting the current flowing through the power switch device and outputting a sampling voltage; the amplifying circuit is used for amplifying the sampling voltage in an in-phase proportion and then outputting the amplified voltage; the power switching device switching regulation circuit: the output end of the PWM generating circuit and the output end of the amplifying circuit are respectively connected, the voltage value of the PWM generating circuit flowing through the power switch device switch regulating circuit is controlled according to the voltage output by the amplifying circuit, so that the time of a driving signal output to the power switch device by the PWM generating circuit is regulated, and the protection time of different working states of the power switch device is switched on/off, so that the protection caused by the instant overcurrent of the power switch device is avoided.

Description

Power switch device protection circuit, control circuit of power module and power module

Technical Field

The invention belongs to the field of protection of power switch devices, and particularly relates to a power switch device protection circuit of a power switch device, a control circuit of a power module and an electronic module.

Background

In the development process of power circuits, the application and protection of power switching tubes (hereinafter referred to as power switching devices) are increasingly widespread. The power switch device can generally bear short-circuit current within a few microseconds, and some IGBTs (Insulated Gate Bipolar transistors) can bear short-circuit time of even 10us, and are easy to damage after the short-circuit time is exceeded. Thus, in some circuit designs, some short circuit tolerant designs are implemented, i.e., short circuits that occur at the output of the circuit when it is operating at its rated speed, should not generate unacceptable heat and any damage to the device and its components. After the short circuit is eliminated, the device can be operated again without replacing any components or taking any measures (such as switching operation). If the current exceeds the limits of the power switches during longer operation, it may also be damaged by heat generation. In order to avoid overcurrent damage, a load circuit is usually connected with a sampling resistor in series to sample the current, then the gate trigger is closed immediately after overcurrent is judged, and the sampled signal has no regulating function. In designing an electronic circuit, it is often considered whether a MOS transistor or an IGBT is selected as a power switching device. Generally, the MOS tube has the advantages of good high-frequency characteristic, and can work at a frequency of hundreds of kHz and MHz, and has the disadvantages of large on-resistance and large power consumption in high-voltage and large-current occasions; the IGBT is excellent in performance under low-frequency and high-power occasions, small in on-resistance and high in voltage resistance.

However, the following problems are common in the circuit design of the power switching device:

firstly, if the load is capacitive, or the instantaneous current of the power switch device caused by surge current exceeds the set value, the power switch device is immediately closed, and the normal operation is influenced. Especially, when the pulse width is very narrow and the current is very large, the circuit is easy to be damaged.

Secondly, the on-off of the power switch device changes along with the fluctuation of the sampling value above and below the gate threshold, so that the power switch device is switched off for many times in the on-state period, a lot of burrs are generated on the voltage waveform of the load end, a lot of interference is generated on occasions with high voltage output requirements, and the quality of a power supply is reduced.

Disclosure of Invention

The embodiment of the application provides a power switch device protection circuit, a control circuit of a power supply module and the power supply module, so that the condition that the power switch device can be closed when the current exceeds a set value at the moment of closing or conducting the power switch device is avoided, namely, the protection caused by the instant overcurrent at the moment of closing or conducting the power switch device is avoided.

The present application is described below in terms of various aspects, it being understood that the following embodiments and advantages of the various aspects may be referred to one another.

In a first aspect, the present invention discloses a power switching device protection circuit, comprising: PWM generating circuit, sampling circuit and power switching device switch regulating circuit, wherein:

the output end of the PWM generating circuit is connected with the power switch device;

a sampling circuit: the sampling circuit is used for inputting the current of the power switch device and outputting a sampling voltage;

the power switching device switching regulating circuit: the output end of the PWM generating circuit and the output end of the sampling circuit are respectively connected, the voltage value of the PWM generating circuit flowing through the power switch device switch regulating circuit is controlled according to the voltage output by the sampling circuit, so that the time of a driving signal output to the power switch device by the PWM generating circuit is regulated, and the instantaneous protection time of the power switch device in different working states is further controlled, so that the protection caused by the instantaneous overcurrent of the power switch device in the short-circuit capacity range is avoided.

With reference to the first aspect, in a possible implementation manner, the circuit further includes an amplifying circuit, connected to the output terminal of the sampling circuit and the input terminal of the power switching device switching adjustment circuit, and configured to amplify the sampled voltage in the same phase ratio, and then output the amplified voltage.

With reference to the first aspect, in one possible implementation manner, the power switching device switching adjustment circuit further includes a first switch and a charging sub-circuit, where:

a first switch: one end of the charging sub-circuit is connected with the output end of the PWM generating circuit;

a charging sub-circuit: the input end of the power switch device is connected with the output of the amplifying circuit, the output end of the power switch device is connected with the first switch, when the current flowing through the power switch device exceeds a set value, the voltage is obtained after being adjusted by the amplifying circuit, the voltage is charged through the charging electronic circuit, when the voltage is charged to the first switch and conducted, the output end of the PWM generating circuit is conducted with the ground, and the voltage provided by the PWM generating circuit for the power switch device is reduced, so that the power switch device is turned off.

With reference to the first aspect, in a possible implementation manner, the charging time of the charging sub-circuit is an on-protection time for starting the power switch device to be turned on, and the on-protection time should be less than a maximum short-circuit tolerance time of the power switch device.

With reference to the first aspect, in a possible implementation manner, the power switching device switching adjustment circuit further includes a discharge sub-circuit, configured to control a voltage across the first switch through a discharge of the discharge sub-circuit, so as to control a discharge time, provided by the PWM generation circuit to the switch driving voltage of the power switching device, of the discharge sub-circuit to be an off protection time for starting the power switching device to be turned on;

after the power switch device is switched off, the current flowing through the power switch device is reduced, the sampling voltage is reduced, the voltage passing through the amplifying circuit is reduced, the reduction amount and the reduction time of the voltage of the two ends of the first switch are controlled by the discharge of the discharge sub-circuit, and the power switch device is controlled to be switched on after the time delay protection time is maintained.

With reference to the first aspect, in a possible implementation manner, the first switch is a triode Q2, the charge sub-circuit and the discharge sub-circuit are a charge and discharge sub-circuit, the charge and discharge sub-circuit further includes resistors Rb1, rb2, a capacitor C2 and a resistor Rbe1, the resistors Rb1, rb2, capacitor C2 and resistor Rbe1 constitute the charge sub-circuit, one end of the resistor Rb2 is connected to the output end of the sampling circuit and the capacitor C2, respectively, one end of the resistor Rbe1 is connected to the base of the triode Q2, the other end of the resistor Rb2 is connected to one end of the resistor Rb2, one end of the capacitor C2 is connected to the common end of the resistors Rb1 and Rb2, the other end of the capacitor Rb2 is grounded, the emitter of the triode Q2 is grounded, and the collector is connected to the output of the PWM generating circuit.

With reference to the first aspect, in a possible implementation manner, the charge-discharge electronic circuit further includes a diode D2 allowing the amplifying circuit and the power switching device switching regulating circuit to be unidirectionally conducted, the diode D2 is connected in series with the resistor Rb2, one end of the diode is connected to the output end of the amplifying circuit, the other end of the diode is connected to the capacitor C2 and the resistor Rb1, respectively, and the charge time constant is equal to

The shutdown protection time is related to the charging time constant.

In combination with the first aspect, in a possible implementation manner, the charge and discharge electronic circuit further includes a diode D3, one end of the diode D3 is connected to ground, the other end of the diode D3 is connected to the base of the triode Q2, the capacitor C2, the resistor Rb1 and the resistor Rbe1 form a discharge loop, when the capacitor C2 discharges, the D2 is turned off in the reverse direction, the unidirectional silicon controlled D3 protects the emitter of the triode Q2, and when a reverse overshoot voltage exists in the loop, the unidirectional silicon controlled D3 is turned on in the forward direction, so that overshoot voltages at two ends of the emitter of the triode Q2 are clamped in a preset voltage, and the triode Q2 is prevented from being damaged due to an overlarge reverse voltage.

With reference to the first aspect, in one possible implementation manner, the discharge time constant is τ, = (Rb 1+ Rbe 1) × C2, and the off protection time for starting the power switching device to be turned off is related to the discharge time constant.

With reference to the first aspect, in a possible implementation manner, the sampling circuit includes a pulse transformer having a primary side coil and a secondary side coil, the primary side coil penetrates through the magnetic core, the secondary side coil is wound on the annular magnetic core, two ends of the secondary side coil are connected to an amplifying circuit formed by the amplifying circuit, and two ends of the primary side coil are connected to a sampling current loop formed by the source of the power switch device and the ground.

With reference to the first aspect, in a possible implementation manner, the amplifying circuit further includes an amplifier, and a positive input terminal and a negative input terminal of the amplifier are respectively connected to two ends of the sampling circuit.

With reference to the first aspect, in a possible implementation manner, the amplifying circuit further includes a potentiometer RT, one end of the potentiometer RT is connected to the negative input end of the amplifier, the other end of the potentiometer RT is connected to the output end of the amplifier, and the amplification factor of the amplifying circuit is adjusted by adjusting the potentiometer RT.

In a second aspect, the present invention provides a control circuit of a power module, wherein the power module is configured to receive an input voltage provided by an input power source and provide an output voltage to supply power to a load, the control circuit controls a magnitude of a voltage supplied to the load through a power switch device, and further includes a PWM generating circuit, a sampling circuit, an amplifying circuit, and a control unit, wherein:

a sampling circuit: the power switch device is used for inputting current flowing through the power switch device and outputting a sampling voltage;

a control unit: the output end of the PWM generating circuit and the output end of the sampling circuit are respectively connected, the voltage output by the sampling circuit is adjusted, the time of a driving signal output to the power switch device by the PWM generating circuit is adjusted, and then the instantaneous protection time of the power switch device in different working states is controlled to be switched on/off, so that the protection caused by the instantaneous overcurrent of the power switch device in the short-circuit capacity range is avoided.

With reference to the second aspect, in a possible implementation manner, the control circuit further includes an amplifying circuit, connected to the output terminal of the sampling circuit and the input terminal of the power switching device switching adjustment circuit, and configured to amplify the sampled voltage in the same phase ratio and output the amplified voltage.

With reference to the second aspect, in one possible implementation manner, the control unit is configured to configure a turn-off delay time for turning on the power switch and a turn-on delay time for turning off the power switch, and the turn-off delay time for turning on the power switch should be less than a maximum short-circuit tolerance time of the power switch.

With reference to the second aspect, in a possible implementation manner, the control unit further includes a first switch and a charging sub-circuit, where:

a first switch: one end of the charging sub-circuit is connected with the output end of the PWM generating circuit;

a charging sub-circuit: the input end of the PWM generating circuit is connected with the output of the amplifying circuit, the output end of the PWM generating circuit is connected with the first switch, when the current flowing through the power switch device exceeds a set value, the voltage is obtained after the adjustment of the amplifying circuit, the voltage is charged through the charging electronic circuit, when the voltage is charged to be conducted by the first switch, the output end of the PWM generating circuit is conducted with the ground, and the voltage provided by the PWM generating circuit for the power switch device is reduced, so that the power switch device is turned off.

The charging time of the charging sub-circuit is the closing delay time of the power switch device for starting and closing, and the delay time is smaller than the maximum short circuit tolerance time of the power switch device.

With reference to the second aspect, in a possible implementation manner, the control unit further includes a discharge sub-circuit, configured to control a rise of a voltage across the first switch through a discharge of the discharge sub-circuit, so as to control a rise of a driving voltage provided to the power switching device by the PWM generating circuit, where a discharge time of the discharge sub-circuit is a turn-on delay time for starting a turn-on of the power switching device;

after the power switch device is turned off, the current flowing through the power switch device is reduced, the sampling voltage is reduced along with the reduction of the voltage passing through the amplifying circuit, and the reduction and the time of the current of the control resistor RG are discharged through the discharge sub-circuit, so that the power switch device is controlled to be turned on after maintaining the turn-off delay time.

With reference to the second aspect, in a possible implementation manner, the amplifying circuit further includes an amplifier and a potentiometer RT, a positive input end and a negative input end of the amplifier are respectively connected to two ends of the sampling circuit, one end of the potentiometer RT is connected to the negative input end of the amplifier, and the other end of the potentiometer RT is connected to the output end of the amplifier, and the control circuit controls and adjusts the potentiometer RT to adjust the amplification factor of the amplifying circuit.

In a third aspect, the present invention provides a power module for receiving an input voltage provided by an input power source and providing an output voltage to power a load, the power module comprising:

a direct current supply device for supplying a direct current voltage;

a control circuit for controlling the amplitude of a voltage supplied to a load by a power switching device, further comprising a PWM generation circuit, a sampling circuit, an amplification circuit and a control unit, wherein:

the output end of the PWM generating circuit is respectively connected with the power switch device and the power switch device switching regulating circuit and is used for providing a power switch device switching signal;

a sampling circuit: the sampling voltage is formed for the current flowing through the power switch device;

an amplifying circuit: the device is used for amplifying the sampling voltage in an in-phase proportion and then outputting the amplified voltage;

a control unit: the output end of the PWM generating circuit and the output end of the amplifying circuit are respectively connected, the adjustment is carried out according to the voltage output by the amplifying circuit, the time of the driving signal output by the PWM generating circuit to the power switch device is adjusted, and the instantaneous protection time of the power switch device in different working states is further controlled to avoid the protection caused by the instantaneous overcurrent of the power switch device in the short-circuit capacity range;

and the transformer is connected with the power switching device and the load and used for controlling the on-off of the power switching device through the control circuit to generate pulse voltage so as to provide required voltage for the load.

An electronic device includes the power switch device protection circuit of the second aspect or the power supply module of the third aspect.

By implementing the embodiment of the application, the PWM signal output to the power switch device by the PWM generating circuit is controlled to be large and small, the PWM signal cannot be immediately increased to the on-voltage or decreased to the off-voltage of the power switch device, but the voltage is increased to the on-voltage value when the power switch device enters the on-state after a period of on-protection time, and the voltage is decreased to the off-voltage value when the power switch device is off after a period of off-protection time. Therefore, the output waveform noise caused by instability of the power switch device is prevented from being more. The pulse power supply requiring high or narrow pulse width output for voltage output provides a good solution for unstable output at the instant when the power switch device is turned on.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings used in the description of the embodiments will be briefly introduced below.

FIG. 1 is a schematic diagram of a power switch device protection circuit according to an embodiment of the present disclosure

Fig. 2 is a second schematic diagram of a protection circuit of a power switch device according to an embodiment of the present application;

fig. 3 is a third schematic diagram of a protection circuit of a power switch device according to an embodiment of the present application;

FIG. 4 is a fourth schematic diagram of a protection circuit for a power switching device according to an embodiment of the present application;

fig. 5 is a diagram illustrating an example of a protection circuit of a power switch device according to an embodiment of the present disclosure;

fig. 6 is a schematic circuit diagram of a power module according to an embodiment of the present disclosure.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It should also be understood that the term "and/or" as used in this specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items and includes such combinations.

As used in this specification and the appended claims, the term "if" may be interpreted contextually as "when", "upon" or "in response to a determination" or "in response to a detection". Similarly, the phrase "if it is determined" or "if a [ described condition or event ] is detected" may be interpreted contextually to mean "upon determining" or "in response to determining" or "upon detecting [ described condition or event ]" or "in response to detecting [ described condition or event ]". Furthermore, in the description of the present application and the appended claims, the terms "first," "second," "third," and the like are used for distinguishing between descriptions and not necessarily for describing or implying relative importance. Reference throughout this specification to "one embodiment" or "some embodiments," or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," or the like, in various places throughout this specification are not necessarily all referring to the same embodiment, but rather mean "one or more but not all embodiments" unless specifically stated otherwise. The terms "comprising," "including," "having," and variations thereof mean "including, but not limited to," unless expressly specified otherwise.

The embodiment of the application provides an electronic device which can be applied to a mobile phone, a tablet personal computer, a wearable device, an on-board device, an Augmented Reality (AR)/Virtual Reality (VR) device, a notebook computer, an ultra-mobile personal computer (UMPC), a netbook, a Personal Digital Assistant (PDA) and other terminal devices, and can also be applied to a high-voltage pulse power supply host. The connection described in this application refers to direct or indirect connection. For example, a and B may be directly connected, or a and B may be indirectly connected through one or more other electrical components, for example, a and C may be directly connected, and C and B may be directly connected, so that a and B are connected through C. It is also understood that "a connects to B" described herein may be a direct connection between a and B, or an indirect connection between a and B through one or more other electrical components. In the description of this application, "/" means "or" unless otherwise stated, for example, A/B may mean A or B. "and/or" herein is merely an association relationship describing an associated object, and means that there may be three relationships, for example, a and/or B, and may mean: a exists alone, A and B exist simultaneously, and B exists alone.

It should be noted that, in the embodiment of the present application, the power switch device generally refers to a power Transistor and a switch Transistor in the conventional sense, and may be a Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET), an Insulated Gate Bipolar Transistor (IGBT), a thyristor, a Bipolar power Transistor (Bipolar power Transistor), or a wide bandgap Semiconductor Field Effect Transistor. In the embodiment of the present application, the power transistor and the switch transistor may be different types of transistors, respectively. Illustratively, the power switch device is a MOSFET or an IGBT, and the switching tube is a wide bandgap semiconductor field effect transistor. In the embodiment of the present application, the driving manner of the power switch device is high-level on and low-level off. Illustratively, the power switch receives a high level drive signal and the power switch is turned on. The power switch receives the low level drive signal and the main power switch is turned off. It can be understood that the power switching device in the embodiment of the present application may also adopt other driving manners, and the driving manner of the power switching device in the embodiment of the present application is not limited.

In the embodiment of the present application, the power switch device protection circuit mainly means that necessary protection circuits, such as overvoltage protection, overcurrent protection, and overheat protection, need to be set in order to ensure safe operation of the power switch device. The application example of the application is mainly the protection circuit with narrow pulse width and large current. The power switch device protection circuit is mainly applied to a power module, particularly a control circuit of the power module. The control circuit provided in the embodiments of the present application may include a Pulse-width modulation (PWM) controller, a Central Processing Unit (CPU), another general-purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf programmable gate array (FPGA) or another programmable logic device, a discrete gate or a transistor logic device, and the like.

Please refer to fig. 1, which is a schematic diagram of a power switch device protection circuit for adjusting a switching state of a power switch device 12. It includes: PWM generating circuit 11, sampling circuit 13, amplifier circuit 14 and power switching device switching regulator circuit 15, wherein:

the output end of the PWM generating circuit 11 is respectively connected with the power switch device 12 and the power switch device switch adjusting circuit 15, and is used for providing a switch signal of the power switch device 12;

the sampling circuit 13: a current for inputting the power switch device 12, and outputting a sampling voltage;

the amplifier circuit 14: the device is used for amplifying the sampling voltage in an in-phase proportion and then outputting the amplified voltage;

power switching device switching adjustment circuit 15: the output end of the PWM generating circuit 11 and the output end of the amplifying circuit 14 are respectively connected, and the voltage value of the PWM generating circuit 11 flowing through the power switch adjusting circuit 15 is controlled according to the voltage output by the amplifying circuit 14, so as to adjust the driving voltage output from the PWM generating circuit 11 to the power switch 12, thereby controlling the on/off of the power switch 12 and starting the protection time of the power switch 12 in different working states.

The core of the application lies in: the sampling circuit 13 and the amplifying circuit 14 are used to provide real-time sampling voltage levels of the power switch device 12, and a preferred example is that the output signals of the sampling circuit 13 and the amplifying circuit 14 are changed in proportion to the current flowing through the power switch device 12. The power switching device switching regulator circuit 15 receives this voltage feedback and controls its output, which in turn affects the output of the power switching device 12. In principle, like a voltage feedback control mode, a voltage feedback closed loop is adopted. The duty ratio of the input signal of the PWM generating circuit 11 is adjusted by the power switching device switching adjusting circuit 15 to adjust the duty ratio of the driving signal of the power switching device. More importantly, the present application not only controls the on/off of the power switch device 12, but also can control the transient protection time of the power switch device 12 in the two operating states, so as to avoid the protection caused by transient overcurrent when the power switch device 12 is on/off (the voltage across the capacitor cannot change suddenly, and the protection is controlled by the charging and discharging time delay of the capacitor). Understandably, protection due to transient overcurrents can be understood as protection within the short circuit capability. The applicant makes a description of the short circuit capability or range of short circuit capabilities. The IGBT is mainly used for motor driving and various converters, the short-circuit resistance of the IGBT is one of the reliable operation and safety guarantee of a system, and short-circuit protection can be realized through a shunt resistor connected in a loop in series or desaturation detection and other modes. The IGBT is short-circuited-tolerant, with a certain IGBT type (EconoDUAL) ^TM 3FF600R12ME4 600A 1200V IGBT4) is a data book describing the short-circuit capability, the typical value of the short-circuit current is 2400A when the drive voltage does not exceed 15V, and the device will not be damaged as long as the short-circuit current is successfully turned off within 10us. This model has a short circuit capability in the range of 10us.

In the prior art, for example, when the output voltage is higher, the duty ratio of the output signal of the power chip is reduced, and the output voltage is reduced; when the output voltage is low, the duty ratio of an output signal of the power supply chip is increased, and the output voltage is increased, so that the value of the output voltage of the switching power supply is controlled within a design range; however, when the input voltage range of the switching power supply is relatively wide, the input current is high, and even if the switching power supply outputs with the minimum duty ratio, the output voltage still appears to be high or unstable. The power switch device switch adjusting circuit 15 controls the PWM signal output from the PWM generating circuit 11 to the power switch device 12 to be larger or smaller, and the PWM signal cannot be raised to the on-voltage or the off-voltage of the power switch device 12 immediately, but the voltage is raised to the on-voltage value when the power switch device 12 enters the on-state after a period of on-protection time, and the voltage is reduced to the off-voltage value when the power switch device 12 is turned off after a period of off-protection time in the same way. Therefore, the output waveform noise caused by instability of the power switch device is prevented from being more. The pulse power supply requiring high or narrow pulse width output for voltage output provides a good solution to unstable output at the instant when the power switch device is turned on.

The following description focuses on each component and the functionality that may be implemented in an example circuit. Referring to fig. 2, the power switching device switching regulation circuit 15 may further include a first switch 151 and a charging sub-circuit 152, wherein:

first switch 151: one end of the charging circuit is connected with the output end of the PWM generating circuit 11, and the other end of the charging circuit is connected with the charging electronic circuit 152;

charging sub-circuit 152: the input end of the power switch device 12 is connected with the output of the amplifying circuit 14, the output end of the power switch device is connected with the first switch 151, when the current flowing through the power switch device 12 exceeds a set value, the amplifying circuit 14 adjusts the current to obtain a voltage, the voltage is charged through the charging circuit 152, when the voltage is charged to the conduction of the first switch 151, the output end of the PWM generating circuit 11 is conducted with the ground, and the voltage provided by the PWM generating circuit 11 to the power switch device 12 is reduced, so that the power switch device 12 is turned off.

The charging time of the charging sub-circuit 152 is the turn-on protection time for starting the turn-on of the power switch device 12, and the turn-on protection time should be shorter than the maximum short-circuit tolerance time of the power switch device 12 to prevent the device from being turned off by mistake due to the surge current at the moment of power-on, so that the voltage cannot be output stably.

The setting of the on-protection time is determined by the charging time of the charging sub-circuit 152, so that the appropriate charging sub-circuit 152 can be selected according to the requirement of the power switch device 12 for the on-protection time. The charging sub-circuit 152 may employ a charging device such as a capacitor to control specific charging parameters.

In an example of the present application, referring to fig. 3, the power switch device switching adjustment circuit 15 further includes a discharging sub-circuit 153, configured to control a voltage across the first switch 151 to decrease through discharging of the discharging sub-circuit 153, so as to control a driving voltage provided by the PWM generation circuit 11 to the power switch device switch 12 to increase, where a discharging time of the discharging sub-circuit 153 is an off protection time for starting the power switch device 12 to be turned on; after the power switch device 12 is turned off, the current flowing through the power switch device 12 decreases, the sampling voltage decreases accordingly, the voltage passing through the amplifying circuit 14 also decreases accordingly, and the voltage between the two ends of the first switch 151 is discharged through the discharging sub-circuit 153 to control the voltage decrease amount and time decrease of the two ends of the first switch 151, so that the power switch device 12 is turned on after the time delay of the turn-off protection time.

The charging sub-circuit 152 and the discharging sub-circuit 153 may be two separate circuits, for example, a second switch is designed between the amplifying circuit 14, the electronic circuit 152 and the discharging sub-circuit 153, and when the voltage value output by the amplifying circuit 14 is greater than a certain threshold, the second switch starts the charging time of the charging sub-circuit 152, adjusts the gate-drive voltage of the power switch device, and controls the turn-on protection time. When the voltage value output by the amplifying circuit 14 is smaller than a certain threshold, the charging circuit 152 is turned off through the second switch to work, the discharging circuit 153 is turned on to work, the gate voltage of the power switch device is adjusted, and the turn-off protection time of the conduction is controlled.

In an example of the present application, referring to fig. 4, the charging sub-circuit and the discharging sub-circuit may employ a charging and discharging sub-circuit 154, during the charging time of the charging and discharging sub-circuit 154, the first switch 151 is not turned on, the power switch device 12 cannot immediately increase to the on-state voltage, and after the charging and discharging sub-circuit 154 charges until the first switch 151 is turned on, the voltage signal of the PWM signal flowing through the power switch device 12 decreases, and the power switch device 12 is turned off. When the sampling voltage signal of the sampling circuit 13 decreases and the output voltage of the amplifying circuit 14 also decreases, the charge-discharge electronic circuit 154 enters a discharge state, the discharge time increases, the first switch 151 is still in a conduction state, the power switching device 12 cannot immediately enter the conduction state even if the PWM is in a high level, after the discharge time or state reaches a preset value, the first switch 151 is turned off, and the voltage signal of the PWM signal flowing through the power switching device 12 increases until the power switching device 12 is turned on.

In an application example of the present application, please refer to fig. 5, which is a diagram illustrating a circuit example of a power switch protection circuit. The first switch 151 may be a transistor Q2. The charge-discharge electronic circuit further comprises a resistor Rb1, a capacitor C2 and a resistor Rbe1, rb2, the resistors Rb1, rb2, the capacitor C2 and the resistor Rbe1 form a charge sub-circuit, one end of the resistor Rb2 is respectively connected with the output end of the sampling circuit and the capacitor C2, one end of the resistor Rb1 is connected with the base electrode of the triode Q2, the other end of the resistor Rb1 is grounded, and the resistor Rb1 and the resistor Rbe1 are connected in series and then connected with the C2 in parallel. The emitter of the triode Q2 is grounded, and the collector is connected with the output of the PWM generating circuit.

The charge-discharge electronic circuit also comprises a unidirectional silicon controlled rectifier D2 which allows the amplifying circuit to be in unidirectional conduction with the power switching device switching regulating circuit, the unidirectional silicon controlled rectifier D2 is connected with the resistor Rb2 in series, one end of the unidirectional silicon controlled rectifier D2 is connected with the output end of the amplifying circuit, the other end of the unidirectional silicon controlled rectifier D2 is respectively connected with the capacitor C2 and the resistor Rb1, the charge time constant is

The turn-on protection time is related to the charging time constant.

The charge and discharge electronic circuit 154 further includes a one-way thyristor D3, the one-way thyristor D3 is connected in parallel with the capacitor C2, one end of the one-way thyristor D3 is connected to ground, and the other end of the one-way thyristor D3 is connected to the base of the triode Q2, the capacitor C2, the resistor Rb1, the resistor Rbe1, the triode Q2, and the one-way thyristor D3 form a discharge circuit, when the capacitor C2 discharges, the one-way thyristor D2 is cut off in the reverse direction, the emitter of the triode Q2 is protected by the one-way thyristor D3, and when there is reverse overshoot voltage in the circuit, the one-way thyristor D3 is turned on in the forward direction, so that overshoot voltage clamps at two ends of the emitter of the triode Q2 are within a preset voltage, and damage to the triode Q2 due to the excessive reverse voltage is prevented.

The discharge time constant is τ = (Rb 1+ Rbe 1) × C2, and the turn-off protection time for starting the power switching device to turn off is related to the discharge time constant.

The charging and discharging part of the circuit limits the switching time of the working state of the power switch device, and effectively avoids the protection caused by instantaneous overcurrent at the moment of conducting the power switch device. In the charging time of the capacitor C2, the base voltage of the transistor cannot be immediately raised to the conducting voltage, and the power switch device is still in a conducting state, so that the power switch device can still normally work even if the current at the load end exceeds a limit value. If the set time is exceeded, the power tube enters the cut-off state. In order to protect the power switch device better, after the current at the load end decreases, the output voltage of the amplifying circuit 14 decreases, D2 is cut off, the discharge time of C2 increases, Q2 is still in the conducting state, and even if the PWM is a high level power switch device, the power switch device cannot enter the conducting state immediately. Therefore, the output waveform noise caused by instability of the power switch device is prevented from being more. The pulse power supply requiring high or narrow pulse width output for voltage output provides a good solution to unstable output at the instant when the power switch device is turned on. It is also emphasized that the increase in discharge time delays the increase in the drive signal so that the power switching device cannot immediately return to saturation. Diode D3 protects the emitter junction of transistor Q2. When a reverse overshoot voltage exists in the loop, the D3 is conducted in the forward direction, so that the overshoot voltage at two ends of the Q2 emitter junction is clamped to be about 0.7V, and the Q2 is prevented from being damaged due to the fact that the reverse voltage is too large.

In an example of the present application, the PWM generating circuit 11 is a device for generating a PWM signal, and referring to fig. 5, the PWM signal generated by the PWM generating circuit 11 is connected to the gate of the power switching device Q1 through a resistor RG, and is further connected to the collector of the transistor Q2 through a schottky diode D4.

In one example of the present application, the sampling circuit 13 includes a pulse transformer having a primary side coil and a secondary side coil, the primary side coil passes through a magnetic core, the secondary side coil is wound on an annular magnetic core, two ends of the secondary side coil are connected to an amplifying circuit formed by the amplifying circuit, and two ends of the primary side coil are connected to a sampling current circuit formed by a source of the power switch device and a ground. Sampling circuit 13 can also adopt traditional sampling resistor to carry out voltage sampling, but the sampling resistor of establishing ties among sampling circuit 13 can consume the energy and lead to the efficiency reduction of circuit, and when power switch device protection circuit required the circuit efficiency very high, sampling circuit 13 can adopt toroidal transformer, and elementary passing magnetic core, secondary coiling are on toroidal magnetic core to this has reduced energy consumption, makes power switch device protection circuit more high-efficient. In this example, the large current of the primary is converted into a small current through the sampling resistor by the transformation ratio of the coil, the current on the sampling resistor is small, and the power consumption is greatly reduced. The coil consumes little energy but only a small part of the energy after flowing through the resistor, so that the function of the sampling circuit implemented by the toroidal transformer is a preferred embodiment. In this example, the sampling voltage loop is further provided with a capacitor C3 and a resistor R3, that is, the two ends of the secondary side coil are connected to the sampling voltage loop formed by the drain of the power switch device, the capacitor C3 and the source of the resistor R3.

In an example of the present application, the amplifying circuit 14 further includes an amplifier, and a positive input terminal and a negative input terminal of the amplifier are respectively connected to two terminals of the sampling circuit 13. The amplifying circuit 14 further comprises a potentiometer RT, one end of the potentiometer RT is connected to the negative input end of the amplifier, the other end of the potentiometer RT is connected to the output end of the amplifier, and the amplification factor of the amplifying circuit is adjusted by adjusting the potentiometer RT. Referring to fig. 5, the positive input terminal of the amplifier is connected to one end of the primary coil through a resistor Rb3, and the negative input terminal is connected to the other end of the primary coil through a potentiometer RT and a resistor RE1, thereby forming an amplifying loop. The amplification factor of the amplification circuit is adjusted by adjusting the potentiometer RT. There are many different implementations of the amplifier circuit 14, and the above are examples only.

In conclusion, the pulse transformer can rapidly convert the current flowing through the power switch device into voltage without consuming energy,the efficiency of the power supply is prevented from being improved due to the heating of the series sampling resistor. The in-phase proportional amplifier can adjust the sampling voltage converted by the transformer to obtain an ideal voltage, and the capability of supplying current to a rear stage is also improved. The charging time of C2 is satisfied

The situation that the capacity of the transformer for supplying the charging current to the C2 is insufficient is avoided. The guard time is only related to the C2 charging time as long as the voltage is adjusted. The key point of the application is that the charge-discharge electronic circuit of the C2 is that when the current flowing through the power switch device exceeds a set value, a voltage is obtained after the adjustment of the in-phase proportional amplifier, the voltage charges the C2 through Rb1 and Rbe1, when the voltage on the C2 is charged to the conduction voltage of a Q2 emitter junction, the Q2 is conducted, the voltage of the current flowing through the RG resistor is increased, the voltages at two ends of the RG are increased, the gate of the power switch device is reduced, and the power switch device is turned off. The overcurrent of the power switch device is prevented from being damaged due to the fact that the set time is exceeded. When the power switch device is turned off, the current flowing through the power switch device is immediately reduced, the sampling voltage of the transformer is reduced, the voltage adjusted by the in-phase proportional amplifier is reduced, the voltage at the two ends of the D2 is higher at the left end and lower at the right end, and the C2 starts to discharge. If the discharging link of C2 is not available, Q2 is cut off immediately, the current flowing through RG is reduced, and the voltage of two ends of RG is reduced, so that the gate trigger voltage of the power switching device is increased and is conducted. Therefore, the power switch device is immediately conducted after being turned off, the current flowing through the power switch device is severe in sudden change, and many peaks are mixed in an output waveform. The discharge link of C2 is provided, so that the voltage of the emitter junction of Q2 is slowly reduced, the emitter junction is cut off after maintaining a certain conduction time, the power switch device cannot be immediately conducted, and the current of the power switch device cannot generate peak fluctuation in a PWM pulse.

The power switch device is applied to power management and motor driving, but the protection circuit can play a role in power switch devices which are required to output instantaneous large current. The most common application of power switching device protection circuits is in power supply modules. The principle of the power switch device protection circuit can be used when the electronic equipment comprises a power module.

The electronic equipment provided by the embodiment of the application comprises a power module and a load. The power module is used for receiving an input voltage Vin and providing an output voltage Vout to supply power to a load. The electronic device may also be another structure that includes a power module, a load, and an internal power source. The internal power supply is used for receiving the input voltage Vin and supplying power to the power supply module. The power module is used for receiving power supplied by an internal power supply and providing an output voltage Vout for supplying power to a load. The power switch device protection circuit can be directly applied to a power supply module and used as a control circuit of the power supply module.

Referring to fig. 6, the power module is configured to receive an input voltage provided by an input power source and provide an output voltage to power a load, and the control circuit configured to control the amplitude of the power supply voltage provided to the load through the power switching device further includes a PWM generating circuit, a sampling circuit, an amplifying circuit, and a control unit, where:

the output end of the PWM generating circuit is respectively connected with the power switch device and the power switch device switching regulating circuit and is used for providing a power switch device switching signal;

a sampling circuit: the sampling circuit is used for forming at least one sampling voltage for the current flowing through the power switch device;

an amplification circuit: the device is used for amplifying the sampling voltage in an in-phase proportion and then outputting the amplified voltage;

a control unit: the output end of the PWM generating circuit and the output end of the amplifying circuit are respectively connected, and the voltage output by the amplifying circuit is adjusted to adjust the time of the driving signal output to the power switch device by the PWM generating circuit, so as to control the transient protection time when the power switch device is switched on/off in different working states, and thus, the protection caused by transient overcurrent of the power switch device in the short circuit capacity range is avoided.

The difference from the above example is that the switching adjustment circuit of the power switching device may be implemented not only by a circuit, but also by software such as a controller. In addition, in this embodiment, the PWM generating circuit and the controller are functionally integrated, the PWM generating circuit receives the voltage output by the amplifying circuit, and adjusts the PWM pulse width according to the received voltage, and the control unit is configured with an off delay time for turning on the power switch device and an on delay time for turning off the power switch device, and the off delay time for turning on the power switch device should be shorter than the maximum short circuit tolerance time of the power switch device.

The controller may also be the power switching device switching regulation circuit in the above example. For example, the power switching device switching regulation circuit further includes a first switch and a charging sub-circuit, wherein:

a first switch: one end of the charging sub-circuit is connected with the output end of the PWM generating circuit;

a charging sub-circuit: the input end of the PWM control circuit is connected with the output of the amplifying circuit, the output end of the PWM control circuit is connected with the first switch, when the current flowing through the power switch device exceeds a set value, the voltage is obtained after the adjustment of the amplifying circuit, the voltage is charged through the charging circuit, when the voltage is charged to the conduction of the first switch, the output end of the PWM generating circuit is conducted with the ground, the voltage provided by the PWM generating circuit to the power switch device is reduced, so that the power switch device is turned off,

the charging time of the charging sub-circuit is the closing delay time of the power switch device for starting and closing, and the delay time is smaller than the maximum short-circuit tolerance time of the power switch device.

The power switching device switching regulation circuit further comprises a discharging sub-circuit, wherein the discharging sub-circuit is used for controlling the reduction of the voltage at two ends of the first switch through the discharging of the discharging sub-circuit so as to control the rise of the driving voltage provided for the power switching device switch by the PWM generating circuit, and the discharging time of the discharging sub-circuit is the turn-off protection time for starting and conducting the power switching device;

after the power switch device is turned off, the current flowing through the power switch device is reduced, the sampling voltage is reduced, the voltage passing through the amplifying circuit is reduced, the reduction amount and time of the voltage at two ends of the first switch are controlled by the discharge of the discharge sub-circuit, and the power switch device is controlled to be turned on after the time delay turn-off protection time.

A power module for receiving an input voltage provided by an input power source and providing an output voltage to power a load, comprising:

a direct current supply device for supplying a direct current voltage;

a control circuit for controlling the magnitude of a supply voltage to a load through a power switching device, further comprising a PWM generation circuit, a sampling circuit, an amplification circuit, and a power switching device switching regulation circuit, wherein:

the output end of the PWM generating circuit is respectively connected with the power switch device and the power switch device switch regulating circuit and is used for providing a power switch device switch signal;

a sampling circuit: the sampling circuit is used for inputting current flowing through the power switch device and outputting a sampling voltage;

an amplification circuit: the sampling circuit is used for amplifying the sampling voltage in an in-phase proportion and then outputting the amplified voltage;

the power switching device switching regulating circuit: the output end of the PWM generating circuit and the output end of the amplifying circuit are respectively connected, the voltage value of the PWM generating circuit flowing through the power switch device switch regulating circuit is controlled according to the voltage output by the amplifying circuit, so that the time of a driving signal output to the power switch device by the PWM generating circuit is regulated, and the instantaneous protection time of the power switch device in different working states is further controlled to avoid the protection caused by the instantaneous overcurrent of the power switch device in the short-circuit capacity range;

and the transformer is connected with the power switching device and the load and used for controlling the on-off of the power switching device through the control circuit to generate pulse voltage so as to provide required voltage for the load.

The secondary output HV + and HV-terminals of the transformer are externally connected to a load.

Referring to fig. 6, parameters of elements in the protection circuit using the IGBT according to the embodiment are shown in the above diagram, where the charging time of C2 is about 7 microseconds, and the discharging time is about 14 microseconds. The embodiment is applied to a generating circuit of pulse voltage, DC + is direct current voltage provided internally, and the pulse width of the pulse voltage is controlled by controlling the grid of the IGBT through PWM. By switching on and off of the IGBT, pulse voltage is generated on the pulse transformer T2, and the required voltage amplitude can be achieved by boosting. The secondary output HV + and HV-terminals of the pulse transformer are externally connected with a load circuit. The IGBT FGL40N120ANG short circuit endurance time is 10 microseconds, and the continuous passing current is 40A. The protection time of the IGBT in this example is set to 7 microseconds, which is sufficient, and the IGBT protection current is set to 45A. When the IGBT current is 45A by adjusting the primary and secondary turns ratio of the pulse transformer and the RT potentiometer, the output voltage of U1 is 1.86V. At the instant of pulse voltage generation, if load RL is capacitive or surge current exists, the instantaneous current may exceed 45A, and if there is no charging circuit for C2, Q2 is immediately turned on to pull down the gate voltage of IGBT, which is immediately turned off. Then, the current immediately decreases after the IGBT is turned off, Q2 is immediately turned off, and the IGBT gate voltage recovers and turns on. Therefore, in the process of generating the pulse voltage, peak oscillation is mixed in the pulse voltage, and the quality of power output is influenced. With the C2 charging and discharging circuit, the IGBT can not be damaged due to overlarge current and the voltage can be normally output no matter what property of the load is in within 7 microseconds of the generation of the pulse high voltage. A large current exceeding 7 microseconds causes the IGBT to turn off. After the circuit is closed, the circuit needs longer time to recover, pulse voltage cannot be output immediately, peak voltage superposition cannot occur on the output pulse voltage, and the waveform quality is improved.

An electronic device may include the power switch device protection circuit or the control circuit of the power module. Such as may be used in a shockwave generating circuit.

Application example:

with the improvement of the living standard of people, cardiovascular diseases become a great killer to harm the health of people at present, and the clinical application of the treatment of the cardiovascular diseases proves that the cardiovascular diseases can generate good curative effect on the focus parts of the cardiovascular diseases through the in vitro low-energy shock wave impact. For a shock wave impact treatment system, pulse high voltage is acted on a customized electrode, so that discharge is generated between the electrodes after breakdown to generate instantaneous large current, and the shock wave energy is controlled by controlling the amplitude of the high voltage and the pulse width after breakdown. So that each discharge of the seismic wave system can generate quantitative and controllable sound pressure energy.

In this case, a power device such as FGL40N120AND is used to control the pulsed high voltage, AND when the PWM signal goes high to trigger the gate to turn on FGL40N120AND, the high voltage is generated accordingly. When the PWM signal goes low, FGL40N120AND is turned off, AND the high voltage is terminated. In the implementation process of the embodiment, the overcurrent protection of the power device FGL40N120AND is particularly important. Avoid causing the long-term current exceeding the rated value to flow and damage the circuit. In general overcurrent protection circuit design, a threshold value is set in advance, and a power tube is turned off once a current signal of a sampling circuit reaches the threshold value. For a shock wave treatment system, the protection circuit generates much uncertainty for narrow pulse high voltage. Due to the existence of surge current, at the moment of high voltage generation, the surge current drives the power tube to be turned off, and the high voltage is cut off when no electrode breaks down, so that shock wave energy cannot be generated. The design is based on the inherent short-circuit capability of the power tube, and a time delay protection method is adopted, so that the damage of the power tube due to long-time overcurrent is avoided, and the uncontrollable effect of the instantaneous overcurrent on the narrow pulse high voltage is also avoided. Is an effective protection method.

All functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may be separately regarded as one unit, or two or more units may be integrated into one unit; the integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit. The integrated unit described above in the present application may also be stored in a computer-readable storage medium if it is implemented in the form of a software functional module and sold or used as a separate product. Based on such understanding, the technical solutions of the embodiments of the present application may be essentially implemented or portions thereof that contribute to the prior art may be embodied in the form of a software product stored in a storage medium, and including several instructions for enabling a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the methods of the embodiments of the present application. And the aforementioned storage medium includes: a removable storage device, a ROM, a RAM, a magnetic or optical disk, or various other media that can store program code.

The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.

Claims (20)

1. A power switching device protection circuit, comprising: PWM generating circuit, sampling circuit and power switching device switching regulator circuit, wherein:

the output end of the PWM generating circuit is connected with the power switch device;

a sampling circuit: the power switch device is used for inputting current flowing through the power switch device and outputting a sampling voltage;

the power switching device switching regulating circuit: the output end of the PWM generating circuit and the output end of the sampling circuit are respectively connected, the voltage value of the PWM generating circuit flowing through the power switch device switch regulating circuit is controlled according to the voltage output by the sampling circuit, so as to adjust the time of the driving signal output by the PWM generating circuit to the power switch device, and further control the transient protection time of the power switch device in different working states, and therefore the protection caused by the transient overcurrent of the power switch device in the short-circuit capacity range is avoided.

2. The power switching device protection circuit of claim 1, further comprising an amplifying circuit connected to an output of the sampling circuit and an input of the power switching device switching regulation circuit, for performing in-phase proportional amplification on the sampled voltage and then outputting the amplified voltage.

3. The power switch device protection circuit of claim 2, wherein the power switch device switching regulation circuit further comprises a first switch and a charging subcircuit, wherein:

the first switch: one end of the charging sub-circuit is connected with the output end of the charging sub-circuit;

the charging sub-circuit: the input end of the first switch is connected with the output end of the amplifying circuit, the output end of the first switch is connected with the first switch, and the first switch is used for obtaining a voltage after being adjusted by the amplifying circuit when the current flowing through the power switch device exceeds a set value, the voltage is charged through the charging sub-circuit, when the voltage is charged to the first switch to be conducted, the output end of the PWM generating circuit is conducted with the ground, so that the voltage provided by the PWM generating circuit to the power switch device is reduced, and the power switch device is turned off.

4. The power switch protection circuit of claim 3, wherein the charging time of the charging electronic circuit is a turn-on protection time for the power switch to initiate turn-on, the turn-on protection time being less than a maximum short circuit withstand time of the power switch.

5. The power switch protection circuit of claim 3, wherein the power switch switching regulation circuit further comprises a discharge sub-circuit for controlling a voltage across the first switch by discharging of the discharge sub-circuit, thereby controlling a rise in a switch driving voltage provided to the power switch by the PWM generation circuit, a discharge time of the discharge sub-circuit being an off-protection time for the power switch to start conducting;

after the power switch device is switched off, the current flowing through the power switch device is reduced, the sampling voltage is reduced, the voltage passing through the amplifying circuit is reduced, the voltage reduction amount and time of the two ends of the first switch are controlled by the discharge of the electronic discharge circuit, and the power switch device is controlled to be switched on after the time delay protection time is maintained.

6. The power switch device protection circuit of claim 5, wherein the first switch is a transistor Q2, the charge sub-circuit and the discharge sub-circuit are a charge-discharge sub-circuit, the charge-discharge sub-circuit further comprises resistors Rb1, rb2, a capacitor C2, and a resistor Rbe1, the resistors Rb1, rb2, C2, and Rbe1 constitute the charge sub-circuit, one end of the resistor Rb2 is connected to the output terminal of the sampling circuit and the capacitor C2, respectively, one end of the resistor Rbe1 is connected to the base of the transistor Q2, the other end is connected to one end of the resistor Rb2, one end of the capacitor C2 is connected to the common terminal of the resistors Rb1 and Rb2, the other end is grounded, the emitter of the transistor Q2 is grounded, and the collector is connected to the output of the PWM generation circuit.

7. The power switching device protection circuit of claim 6, wherein the charge-discharge electronic circuit further comprises a diode D2 allowing the amplifying circuit and the power switching device switching regulator circuit to be unidirectionally conducted, the diode D2 is connected in series with a resistor Rb2, one end of the diode is connected to the output end of the amplifying circuit, the other end of the diode is connected to a capacitor C2 and a resistor Rb1, respectively, and the charging time constant is

The off-guard time is related to the charging time constant.

8. The power switch device protection circuit of claim 7, wherein the charge/discharge electronic circuit further comprises a diode D3, one end of which is connected to ground, the other end of which is connected to the base of the transistor Q2, and the capacitor C2, the resistor Rb1 and the resistor Rbe1 form a discharge loop, when the capacitor C2 discharges, the diode D2 is turned off in the reverse direction, the unidirectional thyristor D3 protects the emitter of the transistor Q2, when a reverse overshoot voltage exists in the loop, the unidirectional thyristor D3 is turned on in the forward direction, so that the overshoot voltage at both ends of the emitter of the transistor Q2 is clamped within a preset voltage, and the transistor Q2 is prevented from being damaged due to the excessive reverse voltage.

9. The power switching device protection circuit of claim 8, wherein the discharge time constant is τ' = (Rb 1+ Rbe 1) × C2, the off-protection time to initiate power switching device turn-off being related to the discharge time constant.

10. The power switch device protection circuit of claim 2, wherein the sampling circuit comprises a pulse transformer having a primary side coil and a secondary side coil, the primary side coil passes through a magnetic core, the secondary side coil is wound on an annular magnetic core, two ends of the secondary side coil are connected to an amplifying circuit formed by the amplifying circuit, and two ends of the primary side coil are connected to a sampling current circuit formed by the source of the power switch device and the ground.

11. The power switch protection circuit according to claim 2 or 10, wherein the amplifying circuit further comprises an amplifier, and a positive input terminal and a negative input terminal of the amplifier are respectively connected to two terminals of the sampling circuit.

12. The power switch device protection circuit of claim 11, wherein said amplification circuit further comprises a potentiometer RT, one end of said potentiometer RT being connected to said negative input of said amplifier and the other end of said potentiometer RT being connected to said output of said amplifier, wherein the amplification of said amplification circuit is adjusted by adjusting said potentiometer RT.

13. The control circuit of the power module is characterized in that the power module is used for receiving an input voltage provided by an input power supply and providing an output voltage to supply power to a load, the control circuit controls the amplitude of the voltage supplied to the load through a power switch device, and further comprises a PWM generating circuit, a sampling circuit, an amplifying circuit and a control unit, wherein:

a sampling circuit: the power switch device is used for inputting current flowing through the power switch device and outputting a sampling voltage;

a control unit: the output end of the PWM generating circuit and the output end of the sampling circuit are respectively connected, the time of a driving signal output to the power switch device by the PWM generating circuit is adjusted according to the voltage output by the sampling circuit, and the instantaneous protection time of the power switch device in different working states is further controlled to be switched on/off, so that the protection caused by instantaneous overcurrent of the power switch device in the short-circuit capacity range is avoided.

14. The control circuit of claim 13, further comprising an amplifying circuit connected to the output terminal of the sampling circuit and the input terminal of the power switching device switching regulator circuit, for performing in-phase proportional amplification on the sampled voltage and then outputting the amplified voltage.

15. The control circuit of claim 13, wherein the control unit is configured to configure an off delay time for the power switch to turn on and an on delay time for the power switch to turn off, and the off delay time for the power switch to turn on is smaller than a maximum short circuit tolerance time of the power switch.

16. The control circuit of claim 14 or 15, wherein the control unit further comprises a first switch and a charging sub-circuit, wherein:

a first switch: one end of the charging sub-circuit is connected with the output end of the charging sub-circuit;

a charging sub-circuit: the input end of the PWM generating circuit is connected with the output of the amplifying circuit, the output end of the PWM generating circuit is connected with the first switch, when the current flowing through the power switch device exceeds a set value, the voltage is obtained after the adjustment of the amplifying circuit, the voltage is charged through the charging sub-circuit, when the voltage is charged to the conduction of the first switch, the output end of the PWM generating circuit is conducted with the ground, the voltage provided by the PWM generating circuit to the power switch device is reduced, so that the power switch device is turned off,

the charging time of the charging sub-circuit is the closing delay time of the power switch device for starting and closing, and the delay time is smaller than the maximum short circuit tolerance time of the power switch device.

17. The control circuit of claim 16, wherein the control unit further comprises a discharge sub-circuit for controlling a rise of a voltage across the first switch by a discharge of the discharge sub-circuit to control a rise of a driving voltage provided to the power switch device by the PWM generation circuit, a discharge time of the discharge sub-circuit being a turn-on delay time for the power switch device to turn on;

after the power switch device is turned off, the current flowing through the power switch device is reduced, the sampling voltage is reduced, the voltage passing through the amplifying circuit is reduced, and the discharge of the electronic discharge circuit controls the reduction amount and time of the current of the resistor RG, so that the power switch device is controlled to be turned on after maintaining the turn-off delay time.

18. The control circuit of claim 14, wherein the amplifying circuit further comprises an amplifier and a potentiometer RT, the positive input terminal and the negative input terminal of the amplifier are respectively connected to two ends of the sampling circuit, one end of the potentiometer RT is connected to the negative input terminal of the amplifier, the other end of the potentiometer RT is connected to the output terminal of the amplifier, and the control circuit controls and adjusts the potentiometer RT to adjust the amplification factor of the amplifying circuit.

19. A power module for receiving an input voltage provided by an input power source and providing an output voltage to power a load, comprising:

a direct current supply device for supplying a direct current voltage;

a control circuit for controlling the magnitude of the supply voltage to the load through the power switching device, further comprising a PWM generation circuit, a sampling circuit, an amplification circuit, and a control unit, wherein:

the output end of the PWM generating circuit is respectively connected with the power switch device and the power switch device switching regulating circuit and is used for providing a power switch device switching signal;

a sampling circuit: for forming a sampled voltage for current flowing through the power switching device;

an amplifying circuit: the sampling circuit is used for amplifying the sampling voltage in an in-phase proportion and then outputting the amplified voltage;

a control unit: the output end of the PWM generating circuit and the output end of the amplifying circuit are respectively connected, the adjustment is carried out according to the voltage output by the amplifying circuit, the time of the driving signal output by the PWM generating circuit to the power switch device is adjusted, and the instantaneous protection time of the power switch device in different working states is further controlled to be switched on/off, so that the protection caused by the instantaneous overcurrent of the power switch device in the short-circuit capacity range is avoided;

and the transformer is connected with the power switch device and the load and used for controlling the on-off of the power switch device through the control circuit to generate pulse voltage and provide required voltage for the load.

20. An electronic device comprising a power switch device protection circuit as claimed in any one of claims 1 to 12 or a control circuit employing a power module as claimed in any one of claims 13 to 18.

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