Modularized three-phase short circuit detection circuit

Abstract

The utility model discloses a modularized three-phase short circuit detection circuit, which comprises a module enabling control unit, a signal comparison unit, a self-locking unit, a reference voltage regulation unit and an IGBT (Insulated Gate Bipolar Translator) driving unit, and is characterized in that the input end of the module enabling control unit is used for connecting a first external terminal, and the module enabling control unit is electrically connected with the self-locking unit; the input end of the reference voltage regulation unit is used for accessing detection current, the output end of the reference voltage regulation unit is electrically connected with the signal comparison unit, the output end of the signal comparison unit is electrically connected with the self-locking unit, and the output end of the self-locking unit is electrically connected with the IGBT driving unit. And the output end of the IGBT driving unit is used for driving on or off of an IGBT switch. According to the utility model, modularized connection can be realized, that is, an external terminal can be directly connected, procedures and flows of short circuit detection circuit connection are simplified, schematic diagrams and PCBs do not need to be repeatedly drawn, and time of designers is saved.

Description

Technical Field

[0001] The utility model relates to the field of three-phase short-circuit detection, in particular to a modular three-phase short-circuit detection circuit. Background Technique

[0002] Three-phase short circuit means that two or more lines in a three-phase four-wire system are short-circuited, which is a short circuit between three-phase conductors in a power supply and distribution system. The methods for three-phase short-circuit detection mainly include the following: Temperature detection method: Indirectly detect the occurrence of three-phase short circuit by monitoring the temperature change of power supply system equipment. When a short circuit occurs in equipment or cables, the current will increase, causing the equipment to heat up and the temperature to rise. Therefore, whether there is a short-circuit fault can be judged by the temperature change. Voltage detection method: Detect three-phase short-circuit faults by monitoring the voltage change of the power supply system. When a short-circuit fault occurs, the current suddenly increases, resulting in a voltage drop. Whether there is a short-circuit fault can be judged by monitoring the voltage change. Current detection method: Monitor the current change of the power supply system. When the current increases abnormally, it may indicate the existence of a short-circuit fault. Insulation resistance test method: Use a megohmmeter to measure the insulation resistance between every two phases. If the resistance value is very low, it indicates that there may be a short-circuit phenomenon between the two phases. Resistance inspection method: Use a bridge to measure the DC resistance of each phase winding. The phase with a smaller resistance value may have a short-circuit fault. Short-circuit detector inspection method: Use a short-circuit detector to check whether there is a short-circuit fault. When in use, place the detector on the stator core slot to be inspected and connect it to an ammeter. If the coil is short-circuited, a current will be generated, causing the primary current to increase. By observing the change in the ammeter reading, the location of the short-circuit fault can be found.

[0003] However, the same short-circuit detection circuit is used in many current products of the same type. Repeatedly drawing schematic diagrams and PCBs will waste a lot of the designer's time. Therefore, how to design a universal and modular three-phase detection circuit is an issue that those skilled in the art need to consider. Summary of the Invention

[0004] The purpose of the utility model is to overcome the deficiencies in the prior art and provide a modular three-phase short-circuit detection circuit.

[0005] The purpose of the utility model is achieved by the following technical solutions:

[0006] A modular three-phase short-circuit detection circuit includes: a module enable control unit, a signal comparison unit, a self-locking unit, a reference voltage adjustment unit, and an IGBT drive unit.

[0007] The input end of the module enable control unit is used to connect to a first external terminal, and the module enable control unit is electrically connected to the self-locking unit.

[0008] The input end of the reference voltage regulation unit is used to access the detection current. The output end of the reference voltage regulation unit is electrically connected to the signal comparison unit. The output end of the signal comparison unit is electrically connected to the self-locking unit. The output end of the self-locking unit is electrically connected to the IGBT driving unit. The output end of the IGBT driving unit is used to drive the on or off of the IGBT switch.

[0009] In one embodiment, the module enable control unit includes a triode Q2, a MOS transistor Q1, and a diode. The base of the triode Q2 is electrically connected to the first external terminal. The collector of the triode Q2 is electrically connected to the G pole of the MOS transistor Q1. The D pole of the MOS transistor Q1 is electrically connected to the anode of the diode. The cathode of the diode is electrically connected to the self-locking unit.

[0010] In one embodiment, the self-locking unit includes a resistor R17, a resistor R19, a comparator U3.3, a comparator U3.4, and a triode Q3. One end of the resistor R19 is electrically connected to the reference voltage regulation unit. The other end of the resistor R19 is electrically connected to one end of the resistor R17 and the output end of the comparator U3.3 respectively. The other end of the resistor R17 is electrically connected to the non-inverting input terminal of the comparator U3.4. The non-inverting input terminal of the comparator U3.4 is also electrically connected to the non-inverting input terminal of the comparator U3.3 and the output end of the module enable control unit respectively. The inverting input terminals of the comparator U3.3 and the comparator U3.4 are connected. The output end of the comparator U3.4 is electrically connected to the base of the triode Q3. The output end of the emitter of the triode Q3 is electrically connected to the IGBT driving unit.

[0011] In one embodiment, the reference voltage regulation unit includes a reference voltage regulation branch, a positive reference branch, and a negative reference branch. The input end of the reference voltage regulation branch is used to be electrically connected to the VCC power supply. The output end of the reference voltage regulation branch is electrically connected to the positive reference branch. The output end of the positive reference branch is electrically connected to the signal comparison unit. The input end of the negative reference branch is electrically connected to the VCC2 power supply. The output end of the negative reference branch is electrically connected to the signal comparison unit.

[0012] In one embodiment, the signal comparison unit includes a comparator U4.1 and a comparator U4.2. The inverting input terminals of the comparator U4.1 and the comparator U4.2 are commonly connected to a phase detection current. The non-inverting input terminal of the comparator U4.1 is electrically connected to the positive reference branch. The non-inverting input terminal of the comparator U4.2 is electrically connected to the negative reference branch.

[0013] In one embodiment, the IGBT driving unit includes a control chip U5, a triode Q7, and a triode Q8. The control chip U5 is electrically connected to the output end of the self-locking unit respectively. The output end of the control chip U5 is electrically connected to the bases of the triode Q7 and the triode Q8 respectively. The collector of the triode Q7 is electrically connected to the VCC power supply. The emitter of the triode Q7 is electrically connected to the collector of the triode Q8. The emitter of the triode Q8 is grounded. The emitter of the triode Q7 also serves as the output end of the IGBT driving unit for driving the on or off of the IGBT switch.

[0014] In one embodiment, it further includes an MCU driving control unit. The input end of the MCU driving control unit is used to connect to a second external terminal, and the output end of the MCU driving control unit is electrically connected to the IGBT driving unit.

[0015] The advantages and beneficial effects of the present utility model compared with the prior art are as follows:

[0016] The present utility model is a modular three-phase short-circuit detection circuit. By setting a module enabling control unit, a signal comparison unit, a self-locking unit, a reference voltage adjustment unit, and an IGBT driving unit, modular connection can be achieved, that is, it can be directly connected to external terminals, simplifying the procedures and processes of connecting the short-circuit detection circuit. There is no need to repeatedly draw schematic diagrams and PCBs, saving the time of designers. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a principle block diagram of the modular three-phase short-circuit detection circuit according to an embodiment of the present utility model;

[0018] Figure 2 is Figure 1 the circuit diagram of the modular three-phase short-circuit detection circuit shown in;

[0019] Figure 3 is Figure 1 the circuit diagram of the modular three-phase short-circuit detection circuit shown in;

[0020] Figure 4 is Figure 1 the circuit diagram of the modular three-phase short-circuit detection circuit shown in;

[0021] Figure 5 is Figure 1 the circuit diagram of the modular three-phase short-circuit detection circuit shown in;

[0022] Figure 6 is Figure 1 the circuit diagram of the modular three-phase short-circuit detection circuit shown in;

[0023] Figure 7 For Figure 1 the circuit diagram of the modular three-phase short-circuit detection circuit shown in the figure. Specific implementation mode

[0024] To facilitate the understanding of the present utility model, the present utility model will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present utility model are shown in the drawings. However, the present utility model can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present utility model more thorough and comprehensive.

[0025] Please refer to Figures 1 to 7 , a modular three-phase short-circuit detection circuit, comprising: a module enable control unit, a self-locking unit, a reference voltage adjustment unit, a signal comparison unit, an IGBT drive unit, and an MCU drive control unit;

[0026] The input end of the module enable control unit is used to connect to the first external terminal, and the module enable control unit is electrically connected to the self-locking unit;

[0027] The input end of the reference voltage adjustment unit is used to access the detection current, the output end of the reference voltage adjustment unit is electrically connected to the signal comparison unit, the output end of the signal comparison unit is electrically connected to the self-locking unit, the output end of the self-locking unit is electrically connected to the IGBT drive unit, and the output end of the IGBT drive unit is used to drive the on or off of the IGBT switch.

[0028] In this application, the detection current accessed by the input end of the reference voltage adjustment unit can be the connected third external terminal, that is, the third external terminal is directly connected to the detection current of the three phases, and then connected to the reference voltage adjustment unit. This application is compatible with AC and DC Hall current sensor signals.

[0029] In this way, by setting the module enable control unit, the signal comparison unit, the self-locking unit, the reference voltage adjustment unit and the IGBT drive unit, modular connection can be realized, that is, the external terminal can be directly connected, which simplifies the procedures and processes of the short-circuit detection circuit connection, and there is no need to repeatedly draw the schematic diagram and PCB, saving the time of the designer.

[0030] The input power supply interface of this application has a wide range of voltage input from 5V to 36V, which facilitates users to select power supply using existing power modules. The feedback point uses a zener diode to ensure that the feedback voltage does not exceed the maximum voltage of the MCU pin, thus protecting the MCU. The voltage of VCC2 is stabilized by the zener diode U2 to improve the stability of the reference power supply voltage and prevent the unstable input power supply voltage from affecting the voltage of the reference power supply. The short-circuit protection current magnitude can be adjusted arbitrarily. Positive and negative reference voltages are used, and the reference voltage can be adjusted through resistor R12 and resistor R28.

[0031] Please refer to Figure 2 , the module enable control unit includes a triode Q2, a MOS tube Q1 and a diode. The base of the triode Q2 is electrically connected to the first external terminal. The collector of the triode Q2 is electrically connected to the G pole of the MOS tube Q1. The D pole of the MOS tube Q1 is electrically connected to the anode of the diode. The cathode of the diode is electrically connected to the self-locking unit. Multiple diodes can be set, so that multiple detection circuits can be connected. This application is compatible with three-way short-circuit current detection.

[0032] Please refer to Figure 3 , the self-locking unit includes a resistor R17, a resistor R19, a comparator U3.3, a comparator U3.4 and a triode Q3. One end of the resistor R19 is electrically connected to the reference voltage adjustment unit. The other end of the resistor R19 is respectively electrically connected to one end of the resistor R17 and the output terminal of the comparator U3.3. The other end of the resistor R17 is electrically connected to the non-inverting input terminal of the comparator U3.4. The non-inverting input terminal of the comparator U3.4 is also respectively electrically connected to the non-inverting input terminal of the comparator U3.3 and the output terminal of the module enable control unit. The inverting input terminals of the comparator U3.3 and the comparator U3.4 are connected. The output terminal of the comparator U3.4 is electrically connected to the base of the triode Q3. The output terminal of the emitter of the triode Q3 is electrically connected to the IGBT drive unit.

[0033] Please refer to Figure 4 , the reference voltage adjustment unit includes a reference voltage adjustment branch, a positive reference branch and a negative reference branch. The input terminal of the reference voltage adjustment branch is used to be electrically connected to the VCC power supply. The output terminal of the reference voltage adjustment branch is electrically connected to the positive reference branch. The output terminal of the positive reference branch is electrically connected to the signal comparison unit. The input terminal of the negative reference branch is electrically connected to the VCC2 power supply. The output terminal of the negative reference branch is electrically connected to the signal comparison unit.

[0034] Please refer to Figure 4, the signal comparison unit includes a comparator U4.1 and a comparator U4.2. The inverting inputs of the comparator U4.1 and the comparator U4.2 are commonly connected to a phase detection current. The non-inverting input of the comparator U4.1 is electrically connected to the positive reference branch, and the non-inverting input of the comparator U4.2 is electrically connected to the negative reference branch.

[0035] Please refer to Figure 5 , the IGBT driving unit includes a control chip U5, a triode Q7, and a triode Q8. The control chip U5 is electrically connected to the output end of the self-locking unit respectively. The output end of the control chip U5 is electrically connected to the bases of the triode Q7 and the triode Q8 respectively. The collector of the triode Q7 is electrically connected to the VCC power supply. The emitter of the triode Q7 is electrically connected to the collector of the triode Q8. The emitter of the triode Q8 is grounded. The emitter of the triode Q7 also serves as the output end of the IGBT driving unit for driving the on or off of the IGBT switch.

[0036] Please refer to Figure 6 , the modular three-phase short-circuit detection circuit further includes an MCU driving and controlling unit. The input end of the MCU driving and controlling unit is used to connect to a second external terminal, and the output end of the MCU driving and controlling unit is electrically connected to the IGBT driving unit.

[0037] Working process:

[0038] First, give a high-level pulse signal to KEY_EN to make the self-locking part in a stable state. The functions of the three diodes D1, D2, and D3 are to prevent crosstalk between the three-phase signals.

[0039] When the current signal is input from IA, the signal outputs a signal after being compared with the positive and negative reference voltages. The positive and negative reference voltages can change with the magnitude of the user's protection current.

[0040] When IA is lower than the reference voltage at the V_DAC - REF point and IA is higher than the reference voltage at the -V_DAC - REF point, the CN4 point outputs a high level. The signals are sent to pins 9 and 11 through resistors R19 and R17.

[0041] When the voltage at pin 11 is higher than the voltage at pin 10, pin 13 outputs a high level, and the triode Q3 conducts, and IGBT_OUTA outputs a high level; at the same time, when the signal at pin 9 is higher than the signal at pin 8, pin 14 always outputs a high level.

[0042] A self-locking is formed to make IGBT_OUTA always output a high level. And the voltage is stabilized within the voltage that the single-chip microcomputer can withstand through resistor R16 and diode D7, and then the DL_return_A signal is fed back to the MCU.

[0043] When a short circuit occurs in the main circuit, if the detected terminal IA is higher than the reference voltage at the V_DAC-REF point or IA is lower than the reference voltage at the -V_DAC-REF point, the CN4 point outputs a low level. The signals are sent to pins 9 and 11 through resistors R19 and R17. When the voltage at pin 11 is lower than the voltage at pin 10, pin 13 outputs a low level, the triode Q3 turns off, and IGBT_OUTA outputs a low level; at the same time, when the signal at pin 9 is lower than the signal at pin 8, pin 14 always outputs a low level, forming a self-lock, so that IGBT_OUTA always outputs a low level. Then the DL_return_A signal is fed back to the MCU.

[0044] When the MCU detects the signal of DL_return_A, it immediately drives the IGBT or MOSFET to quickly cut off the power supply.

[0045] After the power supply is cut off, the IA signal may immediately return to the state where IA is lower than the reference voltage at the V_DAC-REF point and IA is higher than the reference voltage at the -V_DAC-REF point. However, due to the existence of the self-lock circuit, the high level of CN4 cannot pass through R19, and only a voltage drop will be generated between CN4 and pin 14.

[0046] The working principles of the other two phases are the same as that of phase A.

[0047] In the IGBT drive unit, when the control chip U5 receives a low level at any one of IGBT_OUTA, IGBT_OUTB, IGBT_OUTC, MCU_to_IGBT1 (controlled by the MCU to control the MCU_to_IGBT pin to control MCU_to_IGBT1), K_out outputs a low level, thereby disconnecting the drive signal of the IGBT or MOSFET and turning off the output. Conversely, it outputs a high level to drive the IGBT or MOSFET to output.

[0048] The above-described embodiments only represent several embodiments of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims

1. A modular three-phase short-circuit detection circuit, characterized in that: include: The module enables the control unit, signal comparison unit, self-locking unit, reference voltage adjustment unit and IGBT drive unit. The input end of the module enabling control unit is used to connect to the first external terminal, and the module enabling control unit is electrically connected to the self-locking unit; The input end of the reference voltage adjustment unit is used to connect the detection current, the output end of the reference voltage adjustment unit is electrically connected to the signal comparison unit, the output end of the signal comparison unit is electrically connected to the self-locking unit, the output end of the self-locking unit is electrically connected to the IGBT driving unit, and the output end of the IGBT driving unit is used to drive the IGBT switch on or off.

2. The modular three-phase short-circuit detection circuit according to claim 1, characterized in that: The module enabling control unit includes a transistor Q2, a MOS transistor Q1 and a diode, the base of the transistor Q2 is electrically connected to the first external terminal, the collector of the transistor Q2 is electrically connected to the G pole of the MOS transistor Q1, the D pole of the MOS transistor Q1 is electrically connected to the anode of the diode, and the cathode of the diode is electrically connected to the self-locking unit.

3. The modular three-phase short-circuit detection circuit according to claim 1, characterized in that: The self-locking unit includes a resistor R17, a resistor R19, a comparator U3.3, a comparator U3.4 and a transistor Q3, one end of the resistor R19 is electrically connected to the reference voltage adjustment unit, the other end of the resistor R19 is electrically connected to one end of the resistor R17 and the output end of the comparator U3.3 respectively, the other end of the resistor R17 is electrically connected to the non-inverting input end of the comparator U3.4, the non-inverting input end of the comparator U3.4 is also electrically connected to the non-inverting input end of the comparator U3.3 and the output end of the module enable control unit respectively, the inverting input end of the comparator U3.3 is connected to the inverting input end of the comparator U3.4, the output end of the comparator U3.4 is electrically connected to the base of the transistor Q3, and the output end of the emitter of the transistor Q3 is electrically connected to the IGBT drive unit.

4. The modular three-phase short-circuit detection circuit according to claim 1, characterized in that: The reference voltage adjustment unit includes a reference voltage adjustment branch, a positive reference branch and a negative reference branch. The input end of the reference voltage adjustment branch is used to be electrically connected to the VCC power supply, the output end of the reference voltage adjustment branch is electrically connected to the positive reference branch, the output end of the positive reference branch is electrically connected to the signal comparison unit, the input end of the negative reference branch is electrically connected to the VCC2 power supply, and the output end of the negative reference branch is electrically connected to the signal comparison unit.

5. The modular three-phase short-circuit detection circuit according to claim 4, characterized in that: The signal comparison unit includes a comparator U4.1 and a comparator U4.

2. The inverting input terminal of the comparator U4.1 and the inverting input terminal of the comparator U4.2 are commonly connected to a phase detection current. The non-inverting input terminal of the comparator U4.1 is electrically connected to the positive reference branch, and the non-inverting input terminal of the comparator U4.2 is electrically connected to the negative reference branch.

6. The modular three-phase short-circuit detection circuit according to claim 1, characterized in that: The IGBT drive unit includes a control chip U5, a transistor Q7 and a transistor Q8. The control chip U5 is electrically connected to the output end of the self-locking unit, respectively. The output end of the control chip U5 is electrically connected to the base of the transistor Q7 and the transistor Q8, respectively. The collector of the transistor Q7 is electrically connected to the VCC power supply, the emitter of the transistor Q7 is electrically connected to the collector of the transistor Q8, the emitter of the transistor Q8 is grounded, and the emitter of the transistor Q7 is also used as the output end of the IGBT drive unit to drive the IGBT switch on or off.

7. The modular three-phase short-circuit detection circuit according to claim 1, characterized in that: It also includes an MCU drive control unit, the input end of the MCU drive control unit is used to connect to the second external terminal, and the output end of the MCU drive control unit is electrically connected to the IGBT drive unit.

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