Low voltage servo protection circuit

Abstract

The utility model discloses a low pressure servo protection circuit contains inverter unit, three -phase current protection module, three -phase current sampling module, bus current protection module and bus voltage detection module, three -phase current protection module divides three ways, each contains comparator, negative pole connects sampling signal, positive pole connects reference signal, three -phase current sampling module divides three ways, and the current signal is amplified and filters and is inputted to operate and put, and the reference voltage after combination processing is exported to control unit, and bus current protection module is with the bus sampling resistance signal collection of inverter unit front end, and exports the overcurrent protection signal, and bus voltage detection module gathers voltage and exports sampling value through voltage division filter and operates and follows the circuit and exports sampling value. The utility model discloses utilize multiple modules to cooperate monitoring UVW three -phase current, bus current and voltage, realize all -round protection of multiple faults, solve the single problem of existing circuit protection mechanism.

Description

Technical Field

[0001] This utility model relates to the field of servo system protection technology, specifically a low-voltage servo protection circuit. Background Technology

[0002] Low-voltage servo systems are widely used in industrial automation, intelligent manufacturing, and other fields, and their operational stability directly affects the normal operation of equipment. During the operation of servo systems, problems such as excessive current and abnormal voltage can easily occur. If protective measures are not taken in time, it can lead to damage to MOSFETs, servo unit failure, or even safety accidents. However, existing servo system protection circuits have shortcomings such as low sensitivity, slow response speed, and simple protection mechanisms, making it difficult to meet the high reliability and safety requirements of low-voltage servo systems. Utility Model Content

[0003] To address the aforementioned problems, this invention provides a low-voltage servo protection circuit that is highly sensitive, has a fast response, and offers comprehensive protection.

[0004] Therefore, the technical solution of this utility model is: a low-voltage servo protection circuit, comprising: The inverter unit consists of 6 MOSFETs, which are divided into three bridge arms. Each bridge arm contains two MOSFETs, one above the other. A sampling resistor is connected in series with each bridge arm to collect the three-phase current of UVW. The three-phase current protection module is divided into three protection units. Each protection unit includes a comparator. The negative terminal of the comparator input is connected to the sampling resistor to collect the signal, and the positive terminal of the comparator input is connected to the reference signal. The three-phase current sampling module is divided into three sampling units. Each sampling unit amplifies and filters the collected current signal before inputting it into the operational amplifier. At the same time, the reference voltage is processed and input into the operational amplifier. The operational amplifier outputs the final current sampling value to the control unit. The bus current protection module, including a bus sampling resistor, is located at the front end of the inverter unit; the bus sampling resistor is used to collect the bus current signal and output an overcurrent protection signal to the control unit. The bus voltage detection module includes a voltage divider filter circuit and an operational amplifier follower circuit, which is used to acquire the bus voltage and output the voltage sample value to the control unit.

[0005] Based on the above scheme and as a preferred embodiment of the above scheme: In the inverter unit, each bridge arm includes two MOSFETs, upper and lower. The drains of all upper MOSFETs are connected to the positive terminal of the DC bus, and the sources of all lower MOSFETs are connected to the negative terminal of the DC bus. The source of the upper MOSFET in each bridge arm is connected to the drain of the lower MOSFET in the same group, and the connection point serves as the phase output terminal.

[0006] Based on the above scheme and as a preferred embodiment of the above scheme: the three-phase current protection module includes a U-phase protection unit, a V-phase protection unit and a W-phase protection unit; The U-phase protection unit uses resistor R28 and capacitor C13 to filter the acquired current signal, and the filtered signal is connected to the negative terminal of the comparator IC8 input. Resistor R25, R32, and capacitor C12 form a reference signal and are connected to the positive terminal of the comparator IC8 input. The V-phase protection unit uses resistor R37 and capacitor C20 to filter the acquired current signal, and the filtered signal is connected to the negative terminal of the comparator IC9 input. Resistors R36, R39 and capacitor C19 form a reference signal and are connected to the positive terminal of the comparator IC9 input. The W-phase protection unit uses resistor R46 and capacitor C24 to filter the acquired current signal, and the filtered signal is connected to the negative terminal of the comparator IC10 input. Resistors R41, R47 and capacitor C23 form a reference signal and are connected to the positive terminal of the comparator IC10 input.

[0007] Based on the above scheme and as a preferred embodiment of the above scheme: the three-phase current sampling module is divided into a U-phase sampling unit, a V-phase sampling unit and a W-phase sampling unit; In the U-phase sampling unit, resistors R15 and R16 collect the U-phase current signal on sampling resistor RS2 and input it into differential amplifier IC2. After differential amplification, it is filtered by resistor R17 and capacitor C8 and then input into operational amplifier IC3. Resistors R20, R21, and capacitor C11 form a reference voltage, which provides a reference voltage for differential amplifier IC2 after passing through the follower of operational amplifier IC3. After passing through resistor R19, it inputs into operational amplifier IC3. The output signal of operational amplifier IC3 is filtered to obtain the U-phase current sampling value. In the V-phase sampling unit, resistors R23 and R24 collect the V-phase current signal on the sampling resistor RS3 and input it into differential amplifier IC4. After differential amplification, it is filtered by resistor R29 and capacitor C15 and then input into operational amplifier IC5. Resistors R33, R34, and capacitor C18 form a reference voltage, which provides a reference voltage to differential amplifier IC4 after passing through the follower of operational amplifier IC5. After passing through resistor R31, it inputs into operational amplifier IC5. The output signal of operational amplifier IC5 is filtered to obtain the V-phase current sampling value. In the W-phase sampling unit, resistors R38 and R40 collect the W-phase current signal on sampling resistor RS4 and input it into differential amplifier IC6. After differential amplification, it is filtered by resistor R42 and capacitor C21 and then input into operational amplifier IC7. Resistors R45, R48, and capacitor C26 form a reference voltage, which provides a reference voltage to differential amplifier IC6 after passing through the follower of operational amplifier IC7. After passing through resistor R44, it inputs into operational amplifier IC7. The output signal of operational amplifier IC7 is filtered to obtain the W-phase current sampling value.

[0008] Based on the above scheme and as a preferred embodiment: the bus current protection module includes transistors Q1 and Q2. The signal collected by the sampling resistor RS1 enters the base of transistor Q1 after passing through resistor R8 and capacitor C4. The emitter of transistor Q1 is connected to the power supply through the current limiting resistor R6. The collector of transistor Q1 is connected to the base of transistor Q2 after being stepped down and filtered. The collector of transistor Q2 is pulled up by resistor R7 and outputs a filtered overcurrent protection signal.

[0009] Based on the above scheme and as a preferred embodiment of the above scheme: the bus voltage detection module includes a voltage divider filter circuit and an operational amplifier follower circuit. The voltage divider filter circuit includes resistors R3, R4, R5 and capacitor C2. The operational amplifier follower circuit includes a remote computing amplifier IC1. The bus voltage is input to the remote computing amplifier IC1 after being stepped down and filtered. The signal output by the remote computing amplifier IC1 is filtered once, stepped down, and filtered twice to obtain the voltage sampling value.

[0010] Compared with the prior art, the beneficial effects of this utility model are: Through the coordinated operation of the three-phase current protection module, the three-phase current sampling module, the bus current protection module, and the bus voltage detection module, the three-phase current, bus current, and bus voltage of UVW can be monitored simultaneously, achieving comprehensive protection against various faults such as excessive current and abnormal voltage, thus solving the problem of the single mechanism of existing protection circuits.

[0011] The three-phase current protection module uses a comparator to directly judge the threshold of the sampled signal, which can quickly trigger the protection. When a fault occurs, it quickly controls the MOSFET of the inverter unit to turn off, cuts off the power output, and avoids damage to the MOSFET. Each module is equipped with multiple filtering circuits to effectively reduce interference, ensure the accuracy of the sampled signal, improve the sensitivity of the protection circuit, and can detect abnormalities in time and take protective measures.

[0012] The sampling resistors RS2, RS3, and RS4 not only achieve sampling and closed-loop control of the three-phase currents UVW, but also quickly trigger overcurrent protection through the comparator circuit; the bus sampling resistor RS1 is specifically used to monitor the bus current, further enhancing overcurrent protection; the bus voltage detection module monitors the voltage status in real time, promptly detects voltage anomalies, effectively protects the servo system from damage, and significantly improves the reliability and safety of low-voltage servo products. Attached Figure Description

[0013] Figure 1 This is the circuit schematic diagram of this utility model; Figure 2 This is the circuit schematic diagram of the inverter unit of this utility model; Figure 3 This is the circuit schematic diagram of the three-phase current protection module of this utility model; Figure 4 This is the circuit schematic diagram of the three-phase current sampling module of this utility model; Figure 5 This is the circuit schematic diagram of the bus current protection module of this utility model; Figure 6 This is a circuit diagram of the bus voltage detection module of this utility model. Detailed Implementation

[0014] See the attached diagram. The low-voltage servo protection circuit described in this embodiment includes an inverter unit, a three-phase current protection module, a three-phase current sampling module, a bus current protection module, and a bus voltage detection module.

[0015] like Figure 2 As shown, the inverter unit includes six MOS transistors M1-M6 that perform inversion, as well as sampling resistors RS2-RS4 and bus sampling resistor RS1.

[0016] The six MOSFETs are divided into three bridge arms, with each bridge arm containing two MOSFETs, one above the other. U-phase bridge arm: composed of M1 (upper MOSFET) and M4 (lower MOSFET); V-phase bridge arm: Composed of M2 (upper MOSFET) and M5 (lower MOSFET); W phase bridge arm: composed of M3 (upper MOSFET) and M6 (lower MOSFET); The drains (D) of all upper MOSFETs (M1, M2, M3) are connected to the positive terminal (P) of the DC bus; the sources (S) of all lower MOSFETs (M4, M5, M6) are connected to the negative terminal (DC-) of the DC bus; the source (S) of M1 is connected to the drain (D) of M4 to form the U-phase output terminal; the source (S) of M2 is connected to the drain (D) of M5 to form the V-phase output terminal; the source (S) of M3 is connected to the drain (D) of M6 to form the W-phase output terminal.

[0017] When the current flowing through RS1-RS4 is too high, M1-M6 are shut down to protect the servo from damage. RS2-RS4 also serve as a sampling set for the three-phase current of UVW, forming a current closed loop. Simultaneously, the P-phase DC-voltage is monitored in real time to detect voltage anomalies, forming a complete and reliable protection mechanism and improving the reliability and safety of low-voltage servo products.

[0018] like Figure 3 As shown, the three-phase current protection module includes corresponding U, V, and W three-phase current protection circuits. When the current in any of the resistors RS2-RS4 is too high, the OC protection signal is triggered, and M1-M6 are turned off. This circuit has the advantages of high sensitivity and fast response. The resistors RS2-RS4 in the figure are the sampling resistors RS2-RS4 in the inverter unit, and IC8, IC9, and IC10 are comparators.

[0019] U-phase current protection circuit: The protection signal acquired by U-phase is filtered by R28 and C13 and then enters the negative terminal of the input of comparator IC8. R25, R32, and C12 form a comparison reference and enter the positive terminal of the input of comparator IC8. When the acquired signal is higher than the comparison reference, the comparator outputs a low level alarm. V-phase current protection circuit: The protection signal acquired by V-phase is filtered by R37 and C20 and then enters the negative terminal of the input of comparator IC9. R36, R39, and C19 form a comparison reference and enter the positive terminal of the input of comparator IC9. When the acquired signal is higher than the comparison reference, the comparator outputs a low-level alarm. W-phase current protection circuit: The protection signal acquired by V-phase is filtered by R46 and C24 and then enters the negative terminal of the input of comparator IC10. R41, R47, and C23 form a comparison reference and enter the positive terminal of the input of comparator IC10. When the acquired signal is higher than the comparison reference, the comparator outputs a low-level alarm. Finally, resistor R26 provides a pull-up level for the output signal, and R27 and C14 filter the protection signal to prevent interference noise from causing false alarms. The three-phase protection signal is combined with the logic.

[0020] like Figure 4As shown, the three-phase current sampling module is divided into a U-phase sampling unit, a V-phase sampling unit, and a W-phase sampling unit; IC2, IC4, and IC6 are low-power rail-to-rail output differential amplifiers, and IC3, IC5, and IC7 are low-power rail-to-rail output operational amplifiers.

[0021] In the U-phase sampling unit, resistors R15 and R16 collect the U-phase current signal on sampling resistor RS2 and input it into differential amplifier IC2. After differential amplification, it is filtered by resistor R17 and capacitor C8 and then input into operational amplifier IC3. Resistors R20, R21, and capacitor C11 form a reference voltage, which provides a reference voltage for differential amplifier IC2 after passing through the follower of operational amplifier IC3. After passing through resistor R19, it inputs into operational amplifier IC3. R22 and C10 filter the op-amp bridge arm signal, and R18 and C9 filter the op-amp output signal to obtain the IU signal as the U-phase current sampling value, which is then sent to the MCU.

[0022] In the V-phase sampling unit, resistors R23 and R24 collect the V-phase current signal on the sampling resistor RS3 and input it into the differential amplifier IC4. After differential amplification, it is filtered by resistor R29 and capacitor C15 and then input into the operational amplifier IC5. Resistors R33, R34, and capacitor C18 form a reference voltage, which provides a reference voltage to the differential amplifier IC4 after passing through the follower of the operational amplifier IC5. It then enters the operational amplifier IC5 after passing through resistor R31. R35 and C17 filter the op-amp bridge arm signal, and R30 and C16 filter the op-amp output signal to obtain the IV signal, which is used as the V-phase current sampling value and sent to the MCU.

[0023] In the W-phase sampling unit, resistors R38 and R40 collect the W-phase current signal on sampling resistor RS4, which enters differential amplifier IC6. After differential amplification, it is filtered by resistor R42 and capacitor C21 before entering operational amplifier IC7. Resistors R45, R48, and capacitor C26 form a reference voltage, which, after passing through the follower of operational amplifier IC7, provides a reference voltage for differential amplifier IC6. This voltage then passes through resistor R44 before entering operational amplifier IC7. R49 and C25 filter the op-amp bridge arm signal, and R43 and C22 filter the op-amp output signal to obtain the IW signal, which is used as the W-phase current sampling value and sent to the MCU. The IU, IV, and IW signals serve as current closed-loop and cumulative load protection under high load conditions.

[0024] like Figure 5As shown, the bus current protection unit includes transistors Q1 (PNP type) and Q2 (NPN type). The signal collected by sampling resistor RS1 enters the base of transistor Q1 after passing through resistor R8 and capacitor C4. The emitter of transistor Q1 is connected to the power supply through current-limiting resistor R6. When the signal exceeds the threshold, the collector of transistor Q1 outputs a high level. R12 and R13 reduce the output signal of transistor Q1. Diode D2 prevents negative signal output. R14 is a pull-down resistor to prevent abnormal operation of transistor Q2. R11 and C7 filter the input signal to prevent interference noise from triggering the protection. R7 is a pull-up resistor. R9 and C5 filter the output of transistor Q2. R10 and C6 filter the above protection output to obtain the OC_P signal, which is sent to the MCU.

[0025] like Figure 6 As shown, in the bus voltage detection unit, R3, R4, R5, and C2 step down and filter the bus voltage and send it to the operational amplifier IC1. IC1 outputs the voltage acquisition signal as a voltage follower. R1 and C3 filter the follower output signal, the microstructure D1 limits the follower output signal, and R2 and C1 filter the signal to obtain the voltage sampling value, which is then sent to the MCU.

[0026] The above description is merely a preferred embodiment of this utility model. The protection scope of this utility model is not limited to the above embodiments. All technical solutions falling within the scope of this utility model's concept are protected. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of this utility model should also be considered within the protection scope of this utility model.

Claims

1. A low-voltage servo protection circuit, characterized in that: include: The inverter unit consists of 6 MOSFETs, which are divided into three bridge arms. Each bridge arm contains two MOSFETs, one above the other. A sampling resistor is connected in series with each bridge arm to collect the three-phase current of UVW. The three-phase current protection module is divided into three protection units. Each protection unit includes a comparator. The negative terminal of the comparator input is connected to the sampling resistor to collect the signal, and the positive terminal of the comparator input is connected to the reference signal. The three-phase current sampling module is divided into three sampling units. Each sampling unit amplifies and filters the collected current signal before inputting it into the operational amplifier. At the same time, the reference voltage is processed and input into the operational amplifier. The operational amplifier outputs the final current sampling value to the control unit. The bus current protection module, including a bus sampling resistor, is located at the front end of the inverter unit; the bus sampling resistor is used to collect the bus current signal and output an overcurrent protection signal to the control unit. The bus voltage detection module includes a voltage divider filter circuit and an operational amplifier follower circuit, which is used to acquire the bus voltage and output the voltage sample value to the control unit.

2. The low-voltage servo protection circuit as described in claim 1, characterized in that: In the inverter unit, each bridge arm contains two MOSFETs, an upper MOSFET and an lower MOSFET. The drains of all the upper MOSFETs are connected to the positive terminal of the DC bus, and the sources of all the lower MOSFETs are connected to the negative terminal of the DC bus. The source of the upper MOSFET in each bridge arm is connected to the drain of the lower MOSFET in the same group, and the connection point serves as the phase output terminal.

3. The low-voltage servo protection circuit as described in claim 1, characterized in that: The three-phase current protection module includes a U-phase protection unit, a V-phase protection unit, and a W-phase protection unit; The U-phase protection unit uses resistor R28 and capacitor C13 to filter the acquired current signal, and the filtered signal is connected to the negative terminal of the comparator IC8 input. Resistor R25, R32, and capacitor C12 form a reference signal and are connected to the positive terminal of the comparator IC8 input. The V-phase protection unit uses resistor R37 and capacitor C20 to filter the acquired current signal, and the filtered signal is connected to the negative terminal of the comparator IC9 input. Resistors R36, R39 and capacitor C19 form a reference signal and are connected to the positive terminal of the comparator IC9 input. The W-phase protection unit uses resistor R46 and capacitor C24 to filter the acquired current signal, and the filtered signal is connected to the negative terminal of the comparator IC10 input. Resistors R41, R47 and capacitor C23 form a reference signal and are connected to the positive terminal of the comparator IC10 input.

4. The low-voltage servo protection circuit as described in claim 1, characterized in that: The three-phase current sampling module is divided into a U-phase sampling unit, a V-phase sampling unit, and a W-phase sampling unit; In the U-phase sampling unit, resistors R15 and R16 collect the U-phase current signal on sampling resistor RS2 and input it into differential amplifier IC2. After differential amplification, it is filtered by resistor R17 and capacitor C8 and then input into operational amplifier IC3. Resistors R20, R21, and capacitor C11 form a reference voltage, which provides a reference voltage for differential amplifier IC2 after passing through the follower of operational amplifier IC3. After passing through resistor R19, it inputs into operational amplifier IC3. The output signal of operational amplifier IC3 is filtered to obtain the U-phase current sampling value. In the V-phase sampling unit, resistors R23 and R24 collect the V-phase current signal on the sampling resistor RS3 and input it into differential amplifier IC4. After differential amplification, it is filtered by resistor R29 and capacitor C15 and then input into operational amplifier IC5. Resistors R33, R34, and capacitor C18 form a reference voltage, which provides a reference voltage to differential amplifier IC4 after passing through the follower of operational amplifier IC5. After passing through resistor R31, it inputs into operational amplifier IC5. The output signal of operational amplifier IC5 is filtered to obtain the V-phase current sampling value. In the W-phase sampling unit, resistors R38 and R40 collect the W-phase current signal on sampling resistor RS4 and input it into differential amplifier IC6. After differential amplification, it is filtered by resistor R42 and capacitor C21 and then input into operational amplifier IC7. Resistors R45, R48, and capacitor C26 form a reference voltage, which provides a reference voltage to differential amplifier IC6 after passing through the follower of operational amplifier IC7. After passing through resistor R44, it inputs into operational amplifier IC7. The output signal of operational amplifier IC7 is filtered to obtain the W-phase current sampling value.

5. The low-voltage servo protection circuit as described in claim 1, characterized in that: The bus current protection module includes transistors Q1 and Q2. The signal collected by the sampling resistor RS1 enters the base of transistor Q1 after passing through resistor R8 and capacitor C4. The emitter of transistor Q1 is connected to the power supply through the current limiting resistor R6. The collector of transistor Q1 is connected to the base of transistor Q2 after being stepped down and filtered. The collector of transistor Q2 is pulled up by resistor R7 and outputs a filtered overcurrent protection signal.

6. The low-voltage servo protection circuit as described in claim 1, characterized in that: The bus voltage detection module includes a voltage divider filter circuit and an operational amplifier follower circuit. The voltage divider filter circuit includes resistors R3, R4, R5, and capacitor C2. The operational amplifier follower circuit includes a remote computing amplifier IC1. The bus voltage is input to the remote computing amplifier IC1 after being stepped down and filtered. The signal output by the remote computing amplifier IC1 is filtered once, stepped down, and filtered twice to obtain the voltage sampling value.

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