SC detection circuit

Abstract

The present invention discloses an SC detection circuit, comprising a first level signal input terminal, a first driving module, a first switch module, a second level signal input terminal, a second driving module, a second switch module, a detection module, a first output terminal, and a second output terminal. The present invention makes it possible for the voltage of the inverter output signal to increase as the output current of the insulated gate bipolar transistor Q2 increases. When the voltage increases to make the reference voltage of the controllable precision voltage regulator U4 2.5V, the cathode of the controllable precision voltage regulator U4 outputs a low level, the photoelectric coupler U3 is turned on, and the detection output signal is a low level. At this time, a fault signal is output, thereby blocking and shielding the output of PWM, protecting the insulated gate bipolar transistor Q1 and the insulated gate bipolar transistor Q2, reducing the cost, and facilitating maintenance.

Description

Technical Field

[0001] The present invention relates to the technical field of SC detection, and more specifically to a SC detection circuit. Background Art

[0002] At present, the industry widely uses the belt in the inverter circuit driving the lower bridge circuit. The cost of the detection optocoupler (such as ACPL-330J) is relatively high compared to the single drive optocoupler, especially when only When part of it is damaged, the cost of repair is greater and cannot meet the demand. Summary of the invention

[0003] The object of the present invention is to overcome the defects of the prior art and provide an SC detection circuit.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] The SC detection circuit comprises a first level signal input terminal, a first driving module, a first switch module, a second level signal input terminal, a second driving module, a second switch module, a detection module, a first output terminal, and a second output terminal; the first level signal input terminal and the second level signal input terminal are both connected to the first driving module and the second driving module, the first switch module is connected to the first driving module, the detection module, and the first output terminal, the second switch module is connected to the second driving module, the detection module, and the first output terminal, the second driving module is also connected to the detection module, the first output terminal is also connected to the detection module, and the second output terminal is connected to the detection module.

[0006] Its further technical solution is: the first driving module includes a power input terminal, a driving photocoupler U1, a resistor R1, a resistor R2, a resistor R3, a capacitor C1, and a transient suppression diode DZ1; the first level signal input terminal is connected to pin 2 of the driving photocoupler U1, the second level signal input terminal is connected to pin 1 of the resistor R2, the pin 2 of the resistor R2 is connected to the pin 3 of the driving photocoupler U1, the pin 8 of the driving photocoupler U1 is connected to the positive electrode of the power input terminal, the pin 5 of the driving photocoupler U1 is connected to the negative electrode of the power input terminal, the pins 6 and 7 of the driving photocoupler U1 are connected to pin 1 of the resistor R1, the pin 2 of the resistor R1 is connected to pin 1 of the resistor R3, the pin 1 of the capacitor C1, the cathode of the transient suppression diode DZ1, and the first switch module is connected, the pin 2 of the resistor R3, the pin 2 of the capacitor C1, and the anode of the transient suppression diode DZ1 are grounded.

[0007] Its further technical solution is: the first switch module is an insulated gate bipolar transistor Q1, the gate of the insulated gate bipolar transistor Q1 is connected to the 2nd foot of the resistor R1, the emitter of the insulated gate bipolar transistor Q1 is connected to the positive electrode of the battery, and the collector of the insulated gate bipolar transistor Q1 is connected to the detection module and the first output end.

[0008] Its further technical solution is: the second driving module includes a voltage input terminal, a driving photocoupler U2, a resistor R4, a resistor R5, a resistor R6, a capacitor C2, and a transient suppression diode DZ2; the first level signal input terminal is connected to pin 2 of the resistor R6, pin 1 of the resistor R6 is connected to pin 3 of the driving photocoupler U1, the second level signal input terminal is connected to pin 2 of the driving photocoupler U2, pin 8 of the driving photocoupler U2 is connected to the positive electrode of the power input terminal, pin 5 of the driving photocoupler U2 is connected to the negative electrode of the power input terminal, pins 6 and 7 of the driving photocoupler U2 are connected to pin 1 of the resistor R4, and the detection module, pin 2 of the resistor R4 is connected to pin 1 of the resistor R5, pin 1 of the capacitor C2, the cathode of the transient suppression diode DZ2, and the second switch module, and pin 2 of the resistor R5, pin 2 of the capacitor C2, and the anode of the transient suppression diode DZ2 are grounded.

[0009] A further technical solution is as follows: the driving photoelectric coupler U1 and the driving photoelectric coupler U2 are of the same model, both of which are TLP350H.

[0010] Its further technical solution is: the second switch module is an insulated gate bipolar transistor Q2, the gate of the insulated gate bipolar transistor Q2 is connected to the 2nd pin of the resistor R4, the collector of the insulated gate bipolar transistor Q2 is connected to the negative electrode of the battery, and the emitter of the insulated gate bipolar transistor Q2 is connected to the detection module and the first output end.

[0011] A further technical solution is as follows: the insulated gate bipolar transistor Q1 and the insulated gate bipolar transistor Q2 are of the same model, both of which are KWBW40N120S3E1.

[0012] Its further technical scheme is: the detection module includes a power supply, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a diode D1, a diode D2, a capacitor C3, a capacitor C4, a controllable precision voltage regulator U4, and a photoelectric coupler U3; pin 2 of the resistor R7 is connected to pins 6 and 7 of the driving photoelectric coupler U2, pin 1 of the resistor R7 is connected to the cathode of the diode, the anode of the diode is connected to pin 1 of the resistor R8, pin 1 of the resistor R12, and the anode of the diode D1; pin 2 of the resistor R8 is connected to the positive electrode of the power supply, the cathode of the diode D1 is connected to the collector of the insulated gate bipolar transistor Q1, the emitter of the insulated gate bipolar transistor Q2, and The first output terminal is connected; pin 2 of resistor R12 is connected to pin 1 of resistor R13, pin 1 of capacitor C4, and the reference electrode of controllable precision voltage-stabilizing source U4, pin 2 of resistor R13, pin 2 of capacitor C4, and the anode of controllable precision voltage-stabilizing source U4 are grounded, the cathode of controllable precision voltage-stabilizing source U4 is connected to pin 1 of resistor R9, and pin 2 of photoelectric coupler U3, pin 2 of resistor R9 is connected to the positive electrode of the power supply, and pin 2 of resistor R10, pin 1 of resistor R10 is connected to pin 1 of photoelectric coupler U3, pin 3 of photoelectric coupler U3 is grounded, pin 4 of photoelectric coupler U3 is connected to pin 1 of resistor R11, pin 1 of capacitor C3, and the second output terminal, pin 2 of resistor R11 is connected to the power supply, and pin 2 of capacitor C3 is grounded.

[0013] Its further technical solution is: the model of the photoelectric coupler U3 is LTV-356T.

[0014] The further technical solution is: the first level signal input terminal is a PWM- signal; the second level signal input terminal is a PWM+ signal; the first output terminal is an inverter output signal for connecting to a motor; the second output terminal is Detect output signal; when PWM-signal and PWM+signal are high level, drive pin 6 and pin 7 of photocoupler U1 to output low voltage, insulated gate bipolar transistor Q1 is cut off, drive pin 6 and pin 7 of photocoupler U2 to output negative voltage, insulated gate bipolar transistor Q2 is cut off, the reference pole of controllable precision voltage regulator U4 is negative voltage, no current flows through the cathode of controllable precision voltage regulator U4, photocoupler U3 is cut off, at this time The detection output signal is a +5V high level; when the PWM- signal is a high level and the PWM+ signal is a low level, the 6th and 7th pins of the photocoupler U1 are driven to output a high voltage, the insulated gate bipolar transistor Q1 is turned on, the 6th and 7th pins of the photocoupler U2 are driven to output a negative voltage, the insulated gate bipolar transistor Q2 is turned off, the reference pole of the controllable precision voltage regulator U4 is a negative voltage, no current passes through the cathode of the controllable precision voltage regulator U4, and the photocoupler U3 is turned off. The detection output signal is a +5V high level; when the PWM- signal is a low level and the PWM+ signal is a high level, the 6th and 7th pins of the photoelectric coupler U1 are driven to output a low voltage, the insulated gate bipolar transistor Q1 is cut off, the 6th and 7th pins of the photoelectric coupler U1 are driven to output a high voltage, and the insulated gate bipolar transistor Q2 is turned on. As the output current of the insulated gate bipolar transistor Q2 increases, the voltage of the inverter output signal will also increase. When the voltage increases to make the reference voltage of the controllable precision voltage regulator U4 2.5V, the cathode of the controllable precision voltage regulator U4 outputs a low level, and the photoelectric coupler U3 is turned on. The detection output signal is at a low level, at this time, a fault signal is output.

[0015] Compared with the prior art, the beneficial effect of the present invention is that as the output current of the insulated gate bipolar transistor Q2 increases, the voltage of the inverter output signal also increases. When the voltage increases to make the reference voltage of the controllable precision voltage regulator U4 2.5V, the cathode of the controllable precision voltage regulator U4 outputs a low level, and the photoelectric coupler U3 is turned on. The detection output signal is at a low level. At this time, a fault signal is output, thereby blocking and shielding the output of the PWM, protecting the insulated gate bipolar transistor Q1 and the insulated gate bipolar transistor Q2, reducing costs, and facilitating maintenance.

[0016] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following specifically cites a preferred embodiment and describes it in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a block diagram of a SC detection circuit of the present invention;

[0018] Figure 2 It is a specific circuit diagram of the SC detection circuit of the present invention. DETAILED DESCRIPTION

[0019] To illustrate the concept and purpose of the present invention, the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly. The connection can be a direct connection or an indirect connection.

[0022] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0023] like Figure 1 to Figure 2 The specific embodiment shown, wherein Figure 1 As shown, a block diagram of the SC detection circuit of the present invention includes a first level signal input terminal 10, a first driving module 20, a first switch module 30, a second level signal input terminal 40, a second driving module 50, a second switch module 60, a detection module 70, a first output terminal 80, and a second output terminal 90; the first level signal input terminal 10 and the second level signal input terminal 40 are both connected to the first driving module 20 and the second driving module 50, the first switch module 30 is connected to the first driving module 20, the detection module 70, and the first output terminal 80, the second switch module 60 is connected to the second driving module 50, the detection module 70, and the first output terminal 80, the second driving module 50 is also connected to the detection module 70, the first output terminal 80 is also connected to the detection module 70, and the second output terminal 90 is connected to the detection module 80.

[0024] Specifically, Figure 2 As shown, the first driving module 20 includes a power input terminal (in this embodiment, corresponding to Figure 2VU+ and VU- in the driving photoelectric coupler U1 are used to power the driving photoelectric coupler U1), the driving photoelectric coupler U1, the resistor R1, the resistor R2, the resistor R3, the capacitor C1, and the transient suppression diode DZ1; the first level signal input terminal 10 is connected to the 2nd pin of the driving photoelectric coupler U1, the second level signal input terminal 40 is connected to the 1st pin of the resistor R2, the 2nd pin of the resistor R2 is connected to the 3rd pin of the driving photoelectric coupler U1, the 8th pin of the driving photoelectric coupler U1 is connected to the positive electrode of the power input terminal, the 5th pin of the driving photoelectric coupler U1 is connected to the negative electrode of the power input terminal, the 6th pin and the 7th pin of the driving photoelectric coupler U1 are connected to the 1st pin of the resistor R1, the 2nd pin of the resistor R1 is connected to the 1st pin of the resistor R3, the 1st pin of the capacitor C1, the cathode of the transient suppression diode DZ1, and the first switch module 30 are connected, the 2nd pin of the resistor R3, the 2nd pin of the capacitor C1, and the anode of the transient suppression diode DZ1 are grounded.

[0025] Specifically, Figure 2 As shown, the first switch module 30 is an insulated gate bipolar transistor Q1, and the gate of the insulated gate bipolar transistor Q1 (corresponding to Figure 2 Pin 1 in the figure) is connected to pin 2 of resistor R1, and the emitter of insulated gate bipolar transistor Q1 (corresponding to Figure 2 2 pins) and the positive electrode of the battery (in this embodiment, corresponding to Figure 2 The P in the figure is the positive pole of the DC bus of the inverter part) and the collector of the insulated gate bipolar transistor Q1 (corresponding to Figure 2 Pin 3 in the circuit) is connected to the detection module 70 and the first output terminal.

[0026] Specifically, Figure 2 As shown, the second driving module 50 includes a voltage input terminal (in this embodiment, corresponding to Figure 2 VB+ and VB- in are used to power the driving photoelectric coupler U2), the driving photoelectric coupler U2, the resistor R4, the resistor R5, the resistor R6, the capacitor C2, and the transient suppression diode DZ2; the first level signal input terminal 10 is connected to the 2nd pin of the resistor R6, the 1st pin of the resistor R6 is connected to the 3rd pin of the driving photoelectric coupler U1, the second level signal input terminal 40 is connected to the 2nd pin of the driving photoelectric coupler U2, the 8th pin of the driving photoelectric coupler U2 is connected to the positive electrode of the power input terminal, the 5th pin of the driving photoelectric coupler U2 is connected to the negative electrode of the power input terminal, the 6th pin and the 7th pin of the driving photoelectric coupler U2 are connected to the 1st pin of the resistor R4, and the detection module 70, the 2nd pin of the resistor R4 is connected to the 1st pin of the resistor R5, the 1st pin of the capacitor C2, the cathode of the transient suppression diode DZ2, and the second switch module 60 are connected, the 2nd pin of the resistor R5, the 2nd pin of the capacitor C2, and the anode of the transient suppression diode DZ2 are grounded.

[0027] The driving photoelectric coupler U1 and the driving photoelectric coupler U2 are of the same model, both of which are TLP350H.

[0028] Specifically, Figure 2 As shown, the second switch module is an insulated gate bipolar transistor Q2, and the gate of the insulated gate bipolar transistor Q2 (corresponding to Figure 2 Pin 1 in the resistor R4 is connected to the collector of the insulated gate bipolar transistor Q2 (corresponding to Figure 2 3 pin in the figure) and the negative terminal of the battery (in this embodiment, corresponding to Figure 2 N in the figure is the negative pole of the DC bus of the inverter part) and the emitter of the insulated gate bipolar transistor Q2 (corresponding to Figure 2 Pin 2 in the circuit) is connected to the detection module 70 and the first output terminal 80.

[0029] The insulated gate bipolar transistor Q1 and the insulated gate bipolar transistor Q2 are of the same model, namely, KWBW40N120S3E1.

[0030] Specifically, Figure 2 As shown, the detection module 70 includes a power supply (in this embodiment, corresponding to Figure 2 VB+ and +5V), resistor R7, resistor R8, resistor R9, resistor R10, resistor R11, resistor R12, resistor R13, diode D1, diode D2, capacitor C3, capacitor C4, controllable precision voltage regulator U4, and photoelectric coupler U3; pin 2 of the resistor R7 is connected to pin 6 and pin 7 of the driving photoelectric coupler U2, pin 1 of the resistor R7 is connected to the cathode of the diode, the anode of the diode is connected to pin 1 of the resistor R8, pin 1 of the resistor R12, and the anode of the diode D1; pin 2 of the resistor R8 is connected to the positive electrode of the power supply, the cathode of the diode D1 is connected to the collector of the insulated gate bipolar transistor Q1, the emitter of the insulated gate bipolar transistor Q2, and the first output terminal; pin 2 of the resistor R12 is connected to pin 1 of the resistor R13, pin 1 of the capacitor C4, and the reference electrode (corresponding to Figure 2 1 pin in the circuit), the 2nd pin of resistor R13, the 2nd pin of capacitor C4, and the anode of controllable precision voltage regulator U4 (corresponding to Figure 2 Pin 2 in the ground) is connected to the cathode of the controllable precision voltage regulator U4 (corresponding to Figure 2 Pin 3 of the photocoupler U3 is connected to pin 1 of resistor R9 and pin 2 of the photocoupler U3, pin 2 of the resistor R9 is connected to the positive electrode of the power supply and pin 2 of the resistor R10, pin 1 of the resistor R10 is connected to pin 1 of the photocoupler U3, pin 3 of the photocoupler U3 is grounded, pin 4 of the photocoupler U3 is connected to pin 1 of the resistor R11, pin 1 of the capacitor C3, and the second output end, pin 2 of the resistor R11 is connected to the power supply, and pin 2 of the capacitor C3 is grounded.

[0031] The model of the photoelectric coupler U3 is LTV-356T, and the model of the controllable precision voltage regulator U4 is TL431I.

[0032] In this embodiment, the first level signal input terminal 10 is a PWM- signal; the second level signal input terminal 40 is a PWM+ signal; the first output terminal 80 is an inverter output signal for connecting to a motor; the second output terminal 90 is Detect output signal; when PWM-signal and PWM+signal are high level, drive pin 6 and pin 7 of photocoupler U1 to output low voltage, insulated gate bipolar transistor Q1 is cut off, drive pin 6 and pin 7 of photocoupler U2 to output negative voltage, insulated gate bipolar transistor Q2 is cut off, the reference pole of controllable precision voltage regulator U4 is negative voltage, no current flows through the cathode of controllable precision voltage regulator U4, photocoupler U3 is cut off, at this time The detection output signal is a +5V high level; when the PWM- signal is a high level and the PWM+ signal is a low level, the 6th and 7th pins of the photocoupler U1 are driven to output a high voltage, the insulated gate bipolar transistor Q1 is turned on, the 6th and 7th pins of the photocoupler U2 are driven to output a negative voltage, the insulated gate bipolar transistor Q2 is turned off, the reference pole of the controllable precision voltage regulator U4 is a negative voltage, no current passes through the cathode of the controllable precision voltage regulator U4, and the photocoupler U3 is turned off. The detection output signal is a +5V high level; when the PWM- signal is a low level and the PWM+ signal is a high level, the 6th and 7th pins of the photoelectric coupler U1 are driven to output a low voltage, the insulated gate bipolar transistor Q1 is cut off, the 6th and 7th pins of the photoelectric coupler U1 are driven to output a high voltage, and the insulated gate bipolar transistor Q2 is turned on. As the output current of the insulated gate bipolar transistor Q2 increases, the voltage of the inverter output signal will also increase. When the voltage increases to make the reference voltage of the controllable precision voltage regulator U4 2.5V, the cathode of the controllable precision voltage regulator U4 outputs a low level, and the photoelectric coupler U3 is turned on. The detection output signal is low level, at this time, the output fault signal ( Output), thereby blocking and shielding the PWM output, protecting the insulated gate bipolar transistor Q1 and the insulated gate bipolar transistor Q2, reducing costs and facilitating maintenance.

[0033] In this embodiment, the components and their models and connection relationships not shown are Figure 2 The specific circuit diagram has been marked and will not be repeated here.

[0034] The above examples are only used to further illustrate the technical content of the present invention, so that readers can understand it more easily, but they do not mean that the implementation of the present invention is limited to this. Any technical extension or re-creation made according to the present invention is protected by the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. SC detection circuit, characterized in that, The invention comprises a first level signal input terminal, a first driving module, a first switch module, a second level signal input terminal, a second driving module, a second switch module, a detection module, a first output terminal, and a second output terminal; the first level signal input terminal and the second level signal input terminal are both connected to the first driving module and the second driving module, the first switch module is connected to the first driving module, the detection module, and the first output terminal, the second switch module is connected to the second driving module, the detection module, and the first output terminal, the second driving module is also connected to the detection module, the first output terminal is also connected to the detection module, and the second output terminal is connected to the detection module; the first driving module comprises a power input terminal, a driving photocoupler U1, a resistor R1, a resistor R2, a resistor R3, a capacitor C1, and a transient suppression diode DZ1; the first level signal input terminal is connected to pin 2 of the driving photocoupler U1, the second level signal input terminal is connected to pin 1 of the resistor R2, and pin 2 of the resistor R2 is connected to the driving photocoupler U1. The 3rd pin of the driving photoelectric coupler U1 is connected, the 8th pin of the driving photoelectric coupler U1 is connected to the positive electrode of the power input terminal, the 5th pin of the driving photoelectric coupler U1 is connected to the negative electrode of the power input terminal, the 6th pin and the 7th pin of the driving photoelectric coupler U1 are connected to the 1st pin of the resistor R1, the 2nd pin of the resistor R1 is connected to the 1st pin of the resistor R3, the 1st pin of the capacitor C1, the cathode of the transient suppression diode DZ1, and the first switch module are connected, the 2nd pin of the resistor R3, the 2nd pin of the capacitor C1, and the anode of the transient suppression diode DZ1 are grounded; the first switch module is an insulated gate bipolar transistor Q1, the gate of the insulated gate bipolar transistor Q1 is connected to the 2nd pin of the resistor R1, the emitter of the insulated gate bipolar transistor Q1 is connected to the positive electrode of the battery, and the collector of the insulated gate bipolar transistor Q1 is connected to the detection module and the first output terminal; the second driving module includes a voltage input terminal, a driving photoelectric coupler U2, a resistor R4, a resistor R5, a resistor R6, a capacitor C2, and a transient suppression diode DZ2; The first level signal input terminal is connected to the 2nd pin of the resistor R6, the 1st pin of the resistor R6 is connected to the 3rd pin of the driving photoelectric coupler U1, the second level signal input terminal is connected to the 2nd pin of the driving photoelectric coupler U2, the 8th pin of the driving photoelectric coupler U2 is connected to the positive electrode of the power input terminal, the 5th pin of the driving photoelectric coupler U2 is connected to the negative electrode of the power input terminal, the 6th pin and the 7th pin of the driving photoelectric coupler U2 are connected to the 1st pin of the resistor R4, and the detection module, the 2nd pin of the resistor R4 is connected to the 1st pin of the resistor R5, the 1st pin of the capacitor C2, and the cathode of the transient suppression diode DZ2. The first output terminal and the second output terminal are connected to the first output terminal, the first output terminal and the second output terminal are connected to the second output terminal, the second ...

2. The SC detection circuit according to claim 1, characterized in that: The IGBT Q1 and IGBT Q2 are of the same model, which is KWBW40N120S3E1.

3. The SC detection circuit according to claim 1, characterized in that: The detection module includes a power supply, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a diode D1, a diode D2, a capacitor C3, a capacitor C4, a controllable precision voltage regulator U4, and a photoelectric coupler U3; the 2nd foot of the resistor R7 is connected to the 6th foot and the 7th foot of the driving photoelectric coupler U2, the 1st foot of the resistor R7 is connected to the cathode of the diode, the anode of the diode is connected to the 1st foot of the resistor R8, the 1st foot of the resistor R12, and the anode of the diode D1; the 2nd foot of the resistor R8 is connected to the positive electrode of the power supply, the cathode of the diode D1 is connected to the collector of the insulated gate bipolar transistor Q1, the emitter of the insulated gate bipolar transistor Q2, and the first output terminal Connection: Pin 2 of resistor R12 is connected to Pin 1 of resistor R13, Pin 1 of capacitor C4, and the reference electrode of controllable precision voltage-stabilizing source U4, Pin 2 of resistor R13, Pin 2 of capacitor C4, and the anode of controllable precision voltage-stabilizing source U4 are grounded, the cathode of controllable precision voltage-stabilizing source U4 is connected to Pin 1 of resistor R9, and Pin 2 of photoelectric coupler U3, Pin 2 of resistor R9 is connected to the positive electrode of the power supply, and Pin 2 of resistor R10, Pin 1 of resistor R10 is connected to Pin 1 of photoelectric coupler U3, Pin 3 of photoelectric coupler U3 is grounded, Pin 4 of photoelectric coupler U3 is connected to Pin 1 of resistor R11, Pin 1 of capacitor C3, and the second output terminal, Pin 2 of resistor R11 is connected to the power supply, and Pin 2 of capacitor C3 is grounded.

4. The SC detection circuit according to claim 3, characterized in that: The model of the photoelectric coupler U3 is LTV-356T.

5. The SC detection circuit according to claim 3, characterized in that: The first level signal input terminal is a PWM- signal; the second level signal input terminal is a PWM+ signal; the first output terminal is an inverter output signal for connecting to a motor; the second output terminal is Detect output signal; When the PWM-signal and the PWM+signal are at a high level, the 6th and 7th pins of the photocoupler U1 are driven to output a low voltage, the insulated gate bipolar transistor Q1 is turned off, the 6th and 7th pins of the photocoupler U2 are driven to output a negative voltage, the insulated gate bipolar transistor Q2 is turned off, the reference pole of the controllable precision voltage regulator U4 is a negative voltage, no current flows through the cathode of the controllable precision voltage regulator U4, and the photocoupler U3 is turned off. The detection output signal is a +5V high level; when the PWM- signal is a high level and the PWM+ signal is a low level, the 6th and 7th pins of the photocoupler U1 are driven to output a high voltage, the insulated gate bipolar transistor Q1 is turned on, the 6th and 7th pins of the photocoupler U2 are driven to output a negative voltage, the insulated gate bipolar transistor Q2 is turned off, the reference pole of the controllable precision voltage regulator U4 is a negative voltage, no current passes through the cathode of the controllable precision voltage regulator U4, and the photocoupler U3 is turned off. The detection output signal is a +5V high level; when the PWM- signal is a low level and the PWM+ signal is a high level, the 6th and 7th pins of the photoelectric coupler U1 are driven to output a low voltage, the insulated gate bipolar transistor Q1 is cut off, the 6th and 7th pins of the photoelectric coupler U1 are driven to output a high voltage, and the insulated gate bipolar transistor Q2 is turned on. As the output current of the insulated gate bipolar transistor Q2 increases, the voltage of the inverter output signal will also increase. When the voltage increases to make the reference voltage of the controllable precision voltage regulator U4 2.5V, the cathode of the controllable precision voltage regulator U4 outputs a low level, and the photoelectric coupler U3 is turned on. The detection output signal is at a low level, at this time, a fault signal is output.

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