Self-locking circuit of overcurrent protection circuit, overcurrent protection circuit and motor driver

Abstract

The utility model relates to a self-locking circuit of an over-current protection circuit, the over-current protection circuit and a motor driver. The self-locking circuit of the over-current protection circuit comprises a first comparison circuit and a first switching tube. The in-phase input end of the comparison circuit is connected to the power supply through the first diode, and is also used as the input end of the self-locking circuit to be connected with the overcurrent detection circuit, the reverse input end is connected with the reference voltage unit, and the output end is connected with the control end of the first switching tube and is used as the first output end of the self-locking circuit to be connected with the control circuit; the control end of the first switching tube is connected with the in-phase input end of the comparison circuit through the second diode, the collector is connected with the power supply, and the emitter serves as the second output end of the self-locking circuit and is connected with the driving circuit. The self-locking circuit is applied to the over-current protection circuit, and by arranging the self-locking circuit, quick response can be realized when an over-current signal is received, so that the timeliness and the reliability of the over-current protection circuit are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of protection circuits, in particular to a self-locking circuit of an overcurrent protection circuit, an overcurrent protection circuit and a motor driver. Background Art

[0002] Bus overcurrent protection is an indispensable function of servo drive / inverter. Its main function is to ensure that the protection device is not damaged when the bus overcurrent or short circuit occurs.

[0003] Existing commonly used busbar overcurrent protection solutions are as follows: Figure 1 As shown in the figure, a low-resistance resistor (mΩ level) connected in series to the bus is sampled, amplified by an op amp, and then compared with the set threshold value. It is sent to the MCU (Microcontroller Unit) after being isolated by an optical coupler. After receiving the overcurrent signal, the MCU turns off the drive signal, thereby achieving the purpose of overcurrent protection for the driver. However, in some extreme cases (such as when the upper and lower bridge arms of the inverter bridge are turned on at the same time due to special reasons), the inverter bridge IGBT is forced to turn off quickly under extremely large short-circuit currents, which easily leads to the inverter bridge IGBT being unable to turn off when it wants to, and the overcurrent response delay time is relatively large.

[0004] Therefore, the existing overcurrent protection circuit has the problem of long overcurrent response delay time and low reliability. Utility Model Content

[0005] In view of the deficiencies of the above-mentioned related technologies, the purpose of the present application is to provide a self-locking circuit, an overcurrent protection circuit and a driver for an overcurrent protection circuit, aiming to solve the problems of low reliability and large overcurrent response delay time of the existing overcurrent protection circuit.

[0006] A self-locking circuit of an overcurrent protection circuit comprises: a first comparison circuit and a first switch tube;

[0007] The in-phase input terminal of the comparison circuit is connected to the power supply via the first diode, and is also connected to the overcurrent detection circuit as the input terminal of the self-locking circuit, the reverse input terminal is connected to the reference voltage unit, the output terminal is connected to the control terminal of the first switch tube and is connected to the control circuit as the first output terminal of the self-locking circuit;

[0008] The control end of the first switch tube is connected to the in-phase input end of the comparison circuit via the second diode, the collector is connected to the power supply, and the emitter is connected to the drive circuit as the second output end of the self-locking circuit.

[0009] The self-locking circuit of the above-mentioned overcurrent protection circuit, when receiving the overcurrent signal from the overcurrent detection circuit, outputs the self-locking signal to the same-direction input terminal through the output terminal of the first comparison circuit, thereby locking the circuit protection state of the self-locking circuit itself, and then shuts off the IGBT of the inverter unit through the drive circuit and maintains the shut-off state, and stops the control circuit from outputting the drive signal to the drive circuit. When receiving the overcurrent signal, the self-locking circuit can respond quickly and enter the overcurrent protection state, thereby improving the timeliness and reliability of the overcurrent protection.

[0010] Optionally, it also includes:

[0011] A first resistor, one end of which is connected to the same-direction input end of the comparison circuit, and the other end of which is grounded;

[0012] A second resistor, one end of the second resistor is connected to the power supply, the other end of the second resistor is connected to the anode of the first diode, and the cathode of the first diode is connected to the non-inverting input end of the comparison circuit.

[0013] Optionally, a voltage stabilizing unit is further included, and the voltage stabilizing unit is connected between the control end of the first switch tube and the second diode.

[0014] Optionally, the voltage stabilizing unit includes: a third resistor and a voltage stabilizing diode;

[0015] One end of the third resistor is connected to the control end of the first switch tube, and the other end is connected in series to the cathode of the voltage regulator diode; the anode of the voltage regulator diode is connected to the anode of the second diode; the cathode of the second diode is connected to the same direction input end of the comparison circuit.

[0016] Optionally, it also includes a self-locking release unit, one end of which is connected to the first output end of the self-locking circuit, and the other end is connected to the second output end of the self-locking circuit; the self-locking release unit is used to release the self-locking state of the self-locking circuit.

[0017] Optionally, the self-locking release unit includes: a third diode, a fourth resistor and an electrolytic capacitor;

[0018] The anode of the third diode is connected to the second output end of the self-locking circuit, and the cathode is connected to the anode of the electrolytic capacitor; the cathode of the electrolytic capacitor is grounded; one end of the fourth resistor is connected to the first output end of the self-locking circuit, and the other end is connected between the third diode and the electrolytic capacitor.

[0019] By setting the self-locking release unit, it is possible to avoid the need to re-power on the device after entering the overcurrent protection state. The self-locking release unit can be used to set the self-locking state time of the self-locking circuit, and automatically release the self-locking state after the set self-locking time is reached, so that the device returns to normal state.

[0020] Based on the same inventive concept, the present application also provides an overcurrent protection circuit, comprising: an overcurrent detection circuit, a drive circuit, a control circuit and the above-mentioned self-locking circuit;

[0021] The input end of the self-locking circuit is connected to the output end of the overcurrent detection circuit, the first output end is connected to the input end of the control circuit, the second output end is connected to the drive circuit, and the drive circuit is also connected to the output end of the control circuit.

[0022] Optionally, the second output terminal of the self-locking circuit is connected to the power supply input terminal of the driving circuit, or is connected to the enable terminal of the driving circuit.

[0023] Optionally, a main circuit is also included, and the main circuit is connected to the overcurrent detection circuit and the drive circuit respectively.

[0024] The overcurrent protection circuit of the present application can respond quickly when receiving an overcurrent signal through the self-locking circuit set up, shut down the IGBT in the inverter unit through the drive circuit in a hardware manner and keep it in the off state, and stop the control circuit from outputting the drive signal to the drive circuit, thereby improving the timeliness and reliability of the overcurrent protection circuit.

[0025] Based on the same inventive concept, the present application also provides a motor driver, including the above-mentioned overcurrent protection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a module block diagram of an existing overcurrent protection circuit;

[0027] Figure 2 A schematic diagram of the structure of a self-locking circuit of an overcurrent protection circuit provided in this embodiment;

[0028] Figure 3 A schematic diagram of the structure of a self-locking circuit of another overcurrent protection circuit provided in this embodiment;

[0029] Figure 4 A schematic diagram of the circuit structure of an overcurrent protection circuit provided in this embodiment. DETAILED DESCRIPTION

[0030] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thoroughly and comprehensively understood.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0032] Existing commonly used busbar overcurrent protection solutions are as follows: Figure 1 As shown in the figure, a low-resistance resistor (mΩ level) connected in series to the bus is sampled, amplified by an op amp, and then compared with the set threshold value, and then sent to the MCU through optocoupler isolation. After receiving the overcurrent signal, the MCU turns off the drive signal, thereby achieving the purpose of driver overcurrent protection. However, in some extreme cases (such as when the upper and lower bridge arms of the inverter bridge are turned on at the same time due to special reasons), the inverter bridge IGBT (Insulated Gate Bipolar Transistor) is forced to shut down quickly under extremely large short-circuit currents, which easily leads to the inverter bridge IGBT being unable to shut down, and the delay of overcurrent response is relatively large.

[0033] Based on this, the present application hopes to provide a solution that can solve the above-mentioned technical problems, the details of which will be described in the subsequent embodiments.

[0034] The present application provides a self-locking circuit of an overcurrent protection circuit, comprising: a first comparison circuit and a first switch tube; the in-phase input terminal of the comparison circuit is connected to a power supply via a first diode, and is also connected to an overcurrent detection circuit as the input terminal of the self-locking circuit, the reverse input terminal is connected to a reference voltage unit, the output terminal is connected to a control terminal of the first switch tube and is connected to a control circuit as the first output terminal of the self-locking circuit; the control terminal of the first switch tube is connected to the in-phase input terminal of the comparison circuit via a second diode, the collector is connected to the power supply, and the emitter is connected to a drive circuit as the second output terminal of the self-locking circuit.

[0035] See also Figure 2 , Figure 2 A schematic diagram of the structure of a self-locking circuit of an overcurrent protection circuit provided in this embodiment, wherein the self-locking circuit comprises: a first comparison circuit corresponding to Figure 2 The comparator in the first switch tube corresponds to Figure 2Q1 in the circuit; the non-inverting input terminal of the comparison circuit is connected to the power supply VCC via the first diode D1, and is also connected to the overcurrent detection circuit as the input terminal of the self-locking circuit, the reverse input terminal is connected to the reference voltage unit, the output terminal is connected to the control terminal of the first switch tube Q1 and is connected to the control circuit as the first output terminal of the self-locking circuit; the control terminal of the first switch tube Q1 is connected to the non-inverting input terminal of the comparison circuit via the second diode D2, the collector is connected to the power supply VCC, and the emitter is connected to the drive circuit as the second output terminal of the self-locking circuit.

[0036] In another embodiment, the self-locking circuit further comprises:

[0037] A first resistor, one end of which is connected to the same-direction input end of the comparison circuit, and the other end of which is grounded;

[0038] A second resistor, one end of the second resistor is connected to the power supply, the other end of the second resistor is connected to the anode of the first diode, and the cathode of the first diode is connected to the non-inverting input end of the comparison circuit.

[0039] See also Figure 2 , Figure 2 One end of the first resistor R1 is connected to the same-direction input end of the comparison circuit, and the other end is grounded; one end of the second resistor R2 is connected to the power supply, and the other end is connected to the positive electrode of the first diode D1, and the negative electrode of the first diode D1 is connected to the same-direction input end of the comparison circuit.

[0040] In another embodiment, the self-locking circuit further includes a voltage stabilizing unit connected between the control end of the first switch tube and the second diode.

[0041] In another embodiment, the voltage stabilizing unit includes: a third resistor, a voltage stabilizing diode;

[0042] One end of the third resistor is connected to the control end of the first switch tube, and the other end is connected in series to the cathode of the voltage regulator diode; the anode of the voltage regulator diode is connected to the anode of the second diode; the cathode of the second diode is connected to the same direction input end of the comparison circuit.

[0043] See also Figure 2 , Figure 2 The middle voltage stabilizing unit includes: a third resistor R3 and a voltage stabilizing diode ZD1. One end of the third resistor R3 is connected to the control end of the first switch tube Q1, and the other end is connected in series to the cathode of the voltage stabilizing diode ZD1. The anode of the voltage stabilizing diode ZD1 is connected to the anode of the second diode D2. The cathode of the second diode D2 is connected to the same direction input end of the comparison circuit.

[0044] Figure 2The working principle of the self-locking circuit shown is: when the motor driver is powered on normally, the voltage value input by the overcurrent detection circuit and VCC to the non-inverting input terminal of the comparator is less than the reference voltage value input by the reference voltage unit to the reverse input terminal of the comparator. At this time, the comparator outputs a low level (0V), thereby further lowering the input voltage of the non-inverting input terminal of the comparator to 0V, so that the PNP transistor Q1 remains in the on state to turn on the drive circuit. At the same time, the comparator outputs a low level (0V) to the control circuit, so that the control circuit is in a normal operating state without alarm. When the motor driver is short-circuited or overcurrent occurs, the voltage value input by the overcurrent detection circuit and VCC to the non-inverting input of the comparator will be greater than the reference voltage value input by the reference voltage unit to the reverse input of the comparator. At this time, the comparator outputs a high level, and the high level output of the comparator continuously forces the non-inverting input of the comparator to be a high level, so that the PNP transistor Q1 remains in the cut-off state, and the IGBT of the inverter unit is turned off by the drive circuit and remains in the off state, thereby realizing the self-locking of the overcurrent signal. At the same time, the comparator outputs a high level to the control circuit, and the control circuit stops outputting the PWM drive signal to the drive circuit. At the same time, since the PNP transistor Q1 has been cut off by the high level output of the comparator, the drive circuit no longer responds to the drive signal sent by the control circuit.

[0045] In another optional embodiment, the self-locking circuit also includes a self-locking release unit, one end of the self-locking release unit is connected to the first output end of the self-locking circuit, and the other end is connected to the second output end of the self-locking circuit; the self-locking release unit is used to release the self-locking state of the self-locking circuit.

[0046] In another optional embodiment, the self-locking release unit includes: a third diode, a fourth resistor and an electrolytic capacitor; the positive electrode of the third diode is connected to the second output end of the self-locking circuit, and the negative electrode is connected to the positive electrode of the electrolytic capacitor; the negative electrode of the electrolytic capacitor is grounded; one end of the fourth resistor is connected to the first output end of the self-locking circuit, and the other end is connected between the third diode and the electrolytic capacitor.

[0047] See also Figure 3 , Figure 3 A schematic diagram of the structure of another self-locking circuit provided in this embodiment. Figure 3 The self-locking release unit includes: a third diode D3, a fourth resistor R4 and an electrolytic capacitor E1; the anode of the third diode D3 is connected to the second output end of the self-locking circuit, and the cathode is connected to the anode of the electrolytic capacitor E1; the cathode of the electrolytic capacitor E1 is grounded; one end of the fourth resistor R4 is connected to the first output end of the self-locking circuit, and the other end is connected between the third diode D3 and the electrolytic capacitor E1.

[0048] Figure 3As shown, the working principle of the self-locking release unit is as follows: when the motor driver is short-circuited or overcurrent occurs, the PNP transistor Q1 is cut off, causing the third diode D3 to be reversely cut off, and the electrolytic capacitor E1 is slowly discharged through the fourth resistor R4, the second diode D2, and the second resistor R2 until the input voltage value of the comparator's in-phase input terminal drops below the reference voltage value of the comparator's reverse input terminal, and the circuit exits the self-locking state. It can be understood that the time for self-locking release can be adjusted by adjusting the parameters of E1, R4, D2, and R2.

[0049] This embodiment provides a self-locking circuit of an overcurrent protection circuit, including: a first comparison circuit, a first switch tube; the in-phase input end of the comparison circuit is connected to the power supply via a first diode, and is also connected to the overcurrent detection circuit as the input end of the self-locking circuit, the reverse input end is connected to the reference voltage unit, the output end is connected to the control end of the first switch tube and is connected to the control circuit as the first output end of the self-locking circuit; the control end of the first switch tube is connected to the in-phase input end of the comparison circuit via a second diode, the collector is connected to the power supply, and the emitter is connected to the drive circuit as the second output end of the self-locking circuit. When the self-locking circuit receives the overcurrent signal of the overcurrent detection circuit, it outputs the self-locking signal to its in-phase input end through the output end of the first comparison circuit, realizes the locking of the circuit protection state of the self-locking circuit itself, and then turns off the IGBT of the inverter unit through the drive circuit and keeps the off state, and makes the control circuit stop outputting the drive signal to the drive circuit. When the self-locking circuit receives the overcurrent signal, it can respond quickly and enter the overcurrent protection state, thereby improving the timeliness and reliability of the overcurrent protection.

[0050] Another embodiment of the utility model

[0051] This embodiment provides an overcurrent protection circuit, which includes an overcurrent detection circuit, a drive circuit, a control circuit, and a self-locking circuit as described in any one of the above embodiments; the input end of the self-locking circuit is connected to the output end of the overcurrent detection circuit, the first output end is connected to the input end of the control circuit, the second output end is connected to the drive circuit, and the drive circuit is also connected to the output end of the control circuit.

[0052] The overcurrent detection circuit in this embodiment is used to detect whether an overcurrent occurs in the busbar. When an overcurrent occurs, an overcurrent signal is output to the self-locking circuit. The control circuit is used to output a PWM pulse drive signal to the drive circuit. The drive circuit is used to amplify the PWM pulse drive signal output by the control circuit to a level sufficient to drive the IGBT circuit in the inverter unit to turn the IGBT on or off. The drive circuit controls the IGBT in the inverter unit to turn on or off based on the output signal of the self-locking circuit and the output signal of the control circuit.

[0053] See also Figure 2 , Figure 2 The input end of the self-locking circuit is connected to the output end of the overcurrent detection circuit, the first output end is connected to the input end of the control circuit, the second output end is connected to the drive circuit, and the drive circuit is also connected to the output end of the control circuit.

[0054] In another optional embodiment, the second output terminal of the self-locking circuit is connected to the power supply input terminal of the driving circuit, or is connected to the enable terminal of the driving circuit.

[0055] See also Figure 2 , Figure 2 The second output terminal of the self-locking circuit is connected to the power supply input terminal of the driving circuit, or is connected to the enable terminal of the driving circuit.

[0056] In another optional embodiment, the overcurrent protection circuit further includes a main circuit, and the main circuit is connected to the overcurrent detection circuit and the drive circuit respectively.

[0057] See also Figure 4 , Figure 4 A schematic diagram of the circuit structure of an overcurrent protection circuit provided in this embodiment. Figure 4 The main circuit is connected to the overcurrent detection circuit and the drive circuit respectively.

[0058] The present embodiment provides an overcurrent protection circuit, including: an overcurrent detection circuit, a drive circuit, a control circuit and a self-locking circuit of the present embodiment; the input end of the self-locking circuit is connected to the output end of the overcurrent detection circuit, the first output end is connected to the input end of the control circuit, the second output end is connected to the drive circuit, and the drive circuit is also connected to the output end of the control circuit. In this embodiment, the main circuit includes a rectifier unit, a DC bus and an inverter unit. When the overcurrent detection circuit detects that the bus in the main circuit is overcurrent or short-circuited, it outputs an overcurrent signal (high level or low level) to the input end of the self-locking circuit. When the self-locking circuit receives the overcurrent signal, it can respond quickly to achieve the locking of the protection state of the self-locking circuit itself, and then shut down the IGBT of the inverter unit in the main circuit through the drive circuit and keep the shutdown state, and stop the control circuit from outputting the PWM pulse drive signal to the drive circuit. In this state, even if the overcurrent signal disappears, the protection function can still be maintained for a period of time, and automatically recover to a normal state after reaching the self-locking time set by the self-locking release unit in the self-locking circuit, thereby improving the reliability and timeliness of the protection circuit.

[0059] This embodiment further provides a motor driver, which includes an overcurrent protection circuit provided by the above embodiment.

[0060] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A self-locking circuit for an overcurrent protection circuit, It is characterized in that include: A first comparison circuit and a first switch tube; The in-phase input terminal of the comparison circuit is connected to the power supply via the first diode, and is also connected to the overcurrent detection circuit as the input terminal of the self-locking circuit, the reverse input terminal is connected to the reference voltage unit, and the output terminal is connected to the control terminal of the first switch tube and is connected to the control circuit as the first output terminal of the self-locking circuit; The control end of the first switch tube is connected to the in-phase input end of the comparison circuit via the second diode, the collector is connected to the power supply, and the emitter is connected to the drive circuit as the second output end of the self-locking circuit.

2. The self-locking circuit according to claim 1, It is characterized in that Also includes: A first resistor, one end of which is connected to the same-direction input end of the comparison circuit, and the other end of which is grounded; A second resistor, one end of the second resistor is connected to the power supply, the other end of the second resistor is connected to the anode of the first diode, and the cathode of the first diode is connected to the non-inverting input end of the comparison circuit.

3. The self-locking circuit according to claim 1, It is characterized in that It also includes a voltage stabilizing unit, which is connected between the control end of the first switch tube and the second diode.

4. The self-locking circuit as claimed in claim 3, It is characterized in that The voltage stabilizing unit includes: a third resistor and a voltage stabilizing diode; One end of the third resistor is connected to the control end of the first switch tube, and the other end is connected in series to the cathode of the voltage regulator diode; the anode of the voltage regulator diode is connected to the anode of the second diode; the cathode of the second diode is connected to the same direction input end of the comparison circuit.

5. The self-locking circuit according to any one of claims 1 to 4, It is characterized in that It also includes a self-locking release unit, one end of which is connected to the first output end of the self-locking circuit, and the other end is connected to the second output end of the self-locking circuit; the self-locking release unit is used to release the self-locking state of the self-locking circuit.

6. The self-locking circuit as claimed in claim 5, It is characterized in that The self-locking release unit includes: a third diode, a fourth resistor and an electrolytic capacitor; The anode of the third diode is connected to the second output end of the self-locking circuit, and the cathode is connected to the anode of the electrolytic capacitor; the cathode of the electrolytic capacitor is grounded; one end of the fourth resistor is connected to the first output end of the self-locking circuit, and the other end is connected between the third diode and the electrolytic capacitor.

7. An overcurrent protection circuit, It is characterized in that include: An overcurrent detection circuit, a drive circuit, a control circuit, and a self-locking circuit as claimed in any one of claims 1 to 6; The input end of the self-locking circuit is connected to the output end of the overcurrent detection circuit, the first output end is connected to the input end of the control circuit, the second output end is connected to the drive circuit, and the drive circuit is also connected to the output end of the control circuit.

8. The overcurrent protection circuit as claimed in claim 7, It is characterized in that The second output terminal of the self-locking circuit is connected to the power supply input terminal of the driving circuit, or is connected to the enable terminal of the driving circuit.

9. The overcurrent protection circuit as claimed in claim 7, It is characterized in that It also includes a main circuit, which is connected to the overcurrent detection circuit and the drive circuit respectively.

10. A motor driver, It is characterized in that include: An overcurrent protection circuit as described in any one of claims 7 to 9.

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