Input open-phase detection circuit of three-phase motor and motor controller
By using a three-phase rectifier step-down circuit, a phase loss and undervoltage comparison circuit, and a signal isolation processing circuit, the problem of false phase loss alarms in the input phase loss detection circuit of a three-phase motor undervoltage condition is solved, achieving accurate identification and protection of key components. It is suitable for input phase loss detection of three-phase motors.
Patent Information
- Application Number
- CN202521330706.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-26
- Publication Date
- 2026-06-16
- Estimated Expiration
- 2035-06-26
Smart Images
Figure CN224366112U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to an input phase loss detection circuit and a motor controller for a three-phase motor. Background Technology
[0002] In the industry, when it comes to DC three-phase motors, only the three-phase terminal phase loss protection of the motor part is usually considered, while the three-phase input of the power supply part is not monitored. This means that when the power supply phase is lost, the product cannot detect the abnormality and continues to operate, eventually leading to product damage and poor product reliability.
[0003] In view of this, the applicant filed a utility model patent on June 2, 2021, entitled "A Three-Phase Power Supply Phase Loss Detection Circuit and a Motor Controller for a BLDC Motor". The specific circuit is as follows... Figure 1 As shown, the circuit first acquires the bus voltage from the three-phase rectifier bridge, and then sends the sampled value to the inverting input of comparator U1A. The comparator U1A outputs the corresponding voltage as the base signal of transistor Q1, and transistor Q1 outputs the corresponding switching signal, which is sent to the microprocessor MCU. This circuit is relatively simple and low in cost. It only requires a comparator + transistor + rectifier bridge to realize the phase loss function. However, it has a drawback: when the input power supply is undervoltage, the output signal is prone to false alarms for phase loss protection. Summary of the Invention
[0004] This utility model provides an input phase loss detection circuit and motor controller for a three-phase motor, solving the technical problem mentioned above where the input phase loss detection circuit for a three-phase motor is prone to falsely reporting a phase loss when the three-phase AC input power supply is undervoltage.
[0005] The technical solution of this utility model is implemented as follows:
[0006] A phase loss detection circuit for a three-phase motor includes a three-phase rectifier step-down circuit and a phase loss comparison circuit. The three-phase AC inputs U, V, and W are connected to the input terminals of the three-phase rectifier step-down circuit, and the output signal Vin of the three-phase rectifier step-down circuit is connected to the input terminal of the phase loss comparison circuit. The circuit is characterized by further including an undervoltage comparison circuit, a signal isolation processing circuit one, and a signal isolation processing circuit two. The output signal Vin is compared with the reference voltage Vref1 of the phase loss comparison circuit and a phase loss signal A1 is output. The phase loss signal A1 is processed by the signal isolation processing circuit one and then input to the microprocessor.
[0007] The output signal Vin of the three-phase rectifier step-down circuit is connected to the input of the undervoltage comparator circuit. The output signal Vin is compared with the reference voltage Vref2 of the undervoltage comparator circuit and an undervoltage signal B1 is output. The undervoltage signal B1 is processed by the signal isolation processing circuit and then input to the microprocessor.
[0008] Preferably, the three-phase rectifier-step-down circuit comprises three rectifier circuits and one step-down circuit. The three rectifier circuits are composed of diodes D1, D2, and D3, respectively. The three-phase AC inputs U, V, and W are connected to the positive terminals of diodes D1, D2, and D3, respectively. The negative terminals of diodes D1, D2, and D3 are connected together. The step-down circuit includes resistors R4, R5, and R21. One end of resistors R4, R5, and R21 is connected in series to the negative terminal of diode D1, and the other end is connected to ground (GND). The output signal Vin is led out between resistors R5 and R21.
[0009] Preferably, the phase loss comparison circuit includes a comparator chip U1B, resistors R9 and R11, and capacitor C4. Resistors R9 and R11 are connected in series, with one end grounded and the other end connected to the power supply VCC. Capacitor C4 is connected in parallel across resistor R11. A reference voltage Vref1 is formed between resistors R9 and R11 and input to pin 6 of the comparator chip U1B. The output signal Vin is connected to pin 5 of the comparator chip U1B, and pin 7 of the comparator chip U1B outputs the phase loss signal A1.
[0010] Preferably, a voltage regulator circuit is provided between the output signal Vin and pin 5 of the comparator chip U1B. The voltage regulator circuit includes a resistor R10, a capacitor C3 and a clamping diode D4. One end of the resistor R10 and capacitor C3 connected in parallel is connected to the output signal Vin, and the other end is grounded to GND. One end of the clamping diode D4 is connected to the power supply VCC, and the other end is grounded to GND. The middle lead of the clamping diode D4 is connected to the output signal Vin.
[0011] Preferably, the undervoltage comparator circuit includes a comparator chip U2B, resistors R15, R19, and R20, capacitors C6 and C8, and diode D5. The output signal Vin is connected to pin 5 of the comparator chip U2B through resistor R15. Resistors R19 and R20 are connected in series, with one end grounded and the other end connected to the power supply VCC. Capacitor C8 is connected in parallel across resistor R20. A reference voltage Vref2 is formed between resistors R19 and R20 and input to pin 6 of the comparator chip U2B. The two ends of capacitor C6 are connected to pin 5 of the comparator chip U2B and ground GND, respectively. Diode D5 is connected in parallel across capacitor C6. Pin 7 of the comparator chip U2B outputs an undervoltage signal B1.
[0012] Preferably, the signal isolation processing circuit includes resistors R2, R6, R7, R1, R3, and R8, capacitors C2 and C1, transistor Q1, and optocoupler BR1.
[0013] Preferably, the signal isolation processing circuit two includes resistors R13, R16, R17, R12, R14, and R18, capacitors C7 and C5, transistor Q2, and optocoupler BR2.
[0014] Preferably, the microprocessor is a single-chip microcomputer (MCU), which determines the status of the three-phase AC inputs U, V, and W based on the received undervoltage signal B1 and phase loss signal A1.
[0015] A motor controller includes a microprocessor, an inverter circuit, and an input phase loss detection circuit for a three-phase motor. The output terminal of the input phase loss detection circuit for the three-phase motor is connected to the input terminal of the microprocessor, and the microprocessor controls the operation of the inverter circuit. The controller is characterized in that the input phase loss detection circuit for the three-phase motor adopts the aforementioned input phase loss detection circuit for a three-phase motor.
[0016] Compared with the prior art, this utility model has the following advantages:
[0017] 1. By using the output signals of the phase loss comparison circuit and the undervoltage comparison circuit, the fault of false phase loss alarm triggered by undervoltage in the three-phase AC input power supply of a three-phase motor can be accurately identified.
[0018] 2. By using signal isolation processing circuit 1 and signal isolation processing circuit 2, the two output signals of the phase loss comparison circuit and the undervoltage comparison circuit are isolated from the input signal of the microprocessor (i.e., single-chip microcomputer MCU). When a short circuit occurs between the three-phase AC input power supplies, it can protect the low-voltage components, such as the microprocessor (i.e., single-chip microcomputer MCU), diodes and other key components from damage.
[0019] 3. This circuit mainly uses three rectifier diodes (D1, D2, D3) + common comparator circuits (i.e., comparator chip U1B and comparator chip U2B) + common optocouplers BR1 and BR2. It has a moderate cost and can be widely used.
[0020] 4. Other advantages of this utility model are described in detail in the embodiments section. Attached Figure Description
[0021] Figure 1 This is a circuit diagram of an input phase loss detection circuit for a three-phase motor in the prior art;
[0022] Figure 2 This is a circuit block diagram of Embodiment 1 of the present invention;
[0023] Figure 3 for Figure 2 The corresponding part of the circuit diagram;
[0024] Figure 4 for Figure 2 The corresponding other part of the circuit diagram;
[0025] Figure 5 This is a circuit block diagram of Embodiment 2 of this utility model. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0027] Example 1:
[0028] like Figures 2 to 4 As shown, this embodiment provides an input phase loss detection circuit for a three-phase motor, including a three-phase rectifier step-down circuit and a phase loss comparison circuit. The three-phase AC inputs U, V, and W are connected to the input terminals of the three-phase rectifier step-down circuit, and the output signal Vin of the three-phase rectifier step-down circuit is connected to the input terminal of the phase loss comparison circuit. The feature is that it also includes an undervoltage comparison circuit, a signal isolation processing circuit one, and a signal isolation processing circuit two. The output signal Vin is compared with the reference voltage Vref1 of the phase loss comparison circuit and a phase loss signal A1 is output. The phase loss signal A1 is processed by the signal isolation processing circuit one and then input to the microprocessor.
[0029] The output signal Vin of the three-phase rectifier step-down circuit is connected to the input of the undervoltage comparator circuit. The output signal Vin is compared with the reference voltage Vref2 of the undervoltage comparator circuit and an undervoltage signal B1 is output. The undervoltage signal B1 is processed by the signal isolation processing circuit and then input to the microprocessor.
[0030] Preferably, the three-phase rectifier-step-down circuit comprises three rectifier circuits and one step-down circuit. The three rectifier circuits are composed of diodes D1, D2, and D3, respectively. The three-phase AC inputs U, V, and W are connected to the positive terminals of diodes D1, D2, and D3, respectively. The negative terminals of diodes D1, D2, and D3 are connected together. The step-down circuit includes resistors R4, R5, and R21. One end of resistors R4, R5, and R21 is connected in series to the negative terminal of diode D1, and the other end is connected to ground (GND). The output signal Vin is led out between resistors R5 and R21.
[0031] Preferably, the phase loss comparison circuit includes a comparator chip U1B, resistors R9 and R11, and capacitor C4. Resistors R9 and R11 are connected in series, with one end grounded and the other end connected to the power supply VCC. Capacitor C4 is connected in parallel across resistor R11. A reference voltage Vref1 is formed between resistors R9 and R11 and input to pin 6 of the comparator chip U1B. The output signal Vin is connected to pin 5 of the comparator chip U1B, and pin 7 of the comparator chip U1B outputs the phase loss signal A1.
[0032] Preferably, a voltage regulator circuit is provided between the output signal Vin and pin 5 of the comparator chip U1B. The voltage regulator circuit includes a resistor R10, a capacitor C3 and a clamping diode D4. One end of the resistor R10 and capacitor C3 connected in parallel is connected to the output signal Vin, and the other end is grounded to GND. One end of the clamping diode D4 is connected to the power supply VCC, and the other end is grounded to GND. The middle lead of the clamping diode D4 is connected to the output signal Vin.
[0033] Preferably, the undervoltage comparator circuit includes a comparator chip U2B, resistors R15, R19, and R20, capacitors C6 and C8, and diode D5. The output signal Vin is connected to pin 5 of the comparator chip U2B through resistor R15. Resistors R19 and R20 are connected in series, with one end grounded and the other end connected to the power supply VCC. Capacitor C8 is connected in parallel across resistor R20. A reference voltage Vref2 is formed between resistors R19 and R20 and input to pin 6 of the comparator chip U2B. The two ends of capacitor C6 are connected to pin 5 of the comparator chip U2B and ground GND, respectively. Diode D5 is connected in parallel across capacitor C6. Pin 7 of the comparator chip U2B outputs an undervoltage signal B1.
[0034] Preferably, the signal isolation processing circuit includes resistors R2, R6, R7, R1, R3, and R8, capacitors C2 and C1, transistor Q1, and optocoupler BR1.
[0035] Preferably, the signal isolation processing circuit two includes resistors R13, R16, R17, R12, R14, and R18, capacitors C7 and C5, transistor Q2, and optocoupler BR2.
[0036] Preferably, the microprocessor is a single-chip microcomputer (MCU). The MCU determines the status of the three-phase AC inputs U, V, and W based on the received undervoltage signal B1 and phase loss signal A1, i.e., whether it is in a normal state, a phase loss state, or an undervoltage state.
[0037] The working principle of this utility model is as follows: Its circuit working principle is as follows:
[0038] (1) When the three-phase AC inputs U, V, and W are not missing a phase and the input voltage is 380V, the voltage signal is rectified by diodes D1, D2, and D3 and stepped down by resistors R4, R5, and R10, and then flows into pin 5 of comparator chip U1B. At this time, the voltage at pin 5 (non-inverting input) of comparator chip U1B is greater than the voltage at pin 6 (inverting input) of comparator chip U1B. Pin 7 of comparator chip U1B outputs a high level. At the same time, transistor Q1 and optocoupler BR1 work. Pin 3 of optocoupler BR1 outputs a high level and sends it to the microcontroller MCU. The voltage at resistor R5 is then filtered by resistors R21, R15, and capacitor C6 before being sent to pin 5 of comparator chip U2B. At this point, the voltage at pin 5 (non-inverting input) of comparator chip U2B is greater than the voltage at pin 6 (inverting input), causing pin 7 of comparator chip U2B to output a high level. Simultaneously, transistor Q2 and optocoupler BR2 operate normally, with pin 3 of optocoupler BR2 outputting a high level, which is then sent to the microcontroller MCU. At this time, the microcontroller MCU determines that no fault signal has occurred, and the motor operates normally.
[0039] (2) When a phase is missing in the three-phase power supply, the voltage Vin at resistor R5 is at zero-crossing point. At this point, the voltage at pin 5 (non-inverting input) of comparator chip U1B is less than the voltage at pin 6 (inverting input), and the voltage at pin 5 (non-inverting input) of comparator chip U2B is also less than the voltage at pin 6 (inverting input). Pins 7 of both comparator chips U1B and U2B output a low level, transistors Q1 and Q2 are cut off, and pins 3 of optocouplers BR1 and BR2 output a low level, which is then sent to the microcontroller MCU. At this time, the microcontroller MCU determines it to be a phase loss fault and does not send a PWM signal, so the motor does not work.
[0040] (3) When the three-phase power supply is not missing a phase, and the input voltage is below the undervoltage point (270V) but within the normal operating range of the power supply, the output voltage of pin 7 of comparator chip U1B is low, transistor Q1 is cut off, and optocoupler BR1 outputs a low level. The output voltage of pin 7 of comparator chip U2B is high, transistor Q2 is turned on, and optocoupler BR2 outputs a high level. At this time, the microcontroller (MCU) determines that there is an undervoltage fault, and the motor does not work.
[0041] The advantages of this invention are: 1. By using the output signals of the phase loss comparison circuit and the undervoltage comparison circuit, the fault of false phase loss alarm triggered by undervoltage in the three-phase AC input power supply of a three-phase motor can be accurately identified. 2. By using signal isolation processing circuit one and signal isolation processing circuit two, the two output signals of the phase loss comparison circuit and the undervoltage comparison circuit are isolated from the input signal of the microprocessor (i.e., single-chip microcomputer MCU). When a short circuit occurs between the three-phase AC input power supplies, it can protect the weak current components, such as the microprocessor (i.e., single-chip microcomputer MCU), diodes and other key components from damage. 3. This circuit mainly uses three rectifier diodes (D1, D2, D3) + common comparison circuits (i.e., comparator chip U1B, comparator chip U2B) + common optocouplers BR1 and BR2, which is moderately priced and can be widely used.
[0042] Example 2:
[0043] like Figure 5 As shown, a motor controller includes a microprocessor, an inverter circuit, and an input phase loss detection circuit for a three-phase motor. The output terminal of the input phase loss detection circuit for the three-phase motor is connected to the input terminal of the microprocessor. The microprocessor controls the operation of the inverter circuit. The characteristic feature is that the input phase loss detection circuit for the three-phase motor adopts the input phase loss detection circuit for a three-phase motor described in Embodiment 1.
[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.
Claims
1. A phase loss detection circuit for a three-phase motor, comprising a three-phase rectifier step-down circuit and a phase loss comparison circuit, wherein the three-phase AC inputs U, V, and W are connected to the input terminals of the three-phase rectifier step-down circuit, and the output signal Vin of the three-phase rectifier step-down circuit is connected to the input terminal of the phase loss comparison circuit, characterized in that: It also includes an undervoltage comparator circuit, a signal isolation processing circuit one, and a signal isolation processing circuit two. The output signal Vin is compared with the reference voltage Vref1 of the phase loss comparator circuit and the phase loss signal A1 is output. The phase loss signal A1 is processed by the signal isolation processing circuit one and then input to the microprocessor. The output signal Vin of the three-phase rectifier step-down circuit is connected to the input of the undervoltage comparator circuit. The output signal Vin is compared with the reference voltage Vref2 of the undervoltage comparator circuit and an undervoltage signal B1 is output. The undervoltage signal B1 is processed by the signal isolation processing circuit and then input to the microprocessor.
2. The input phase loss detection circuit for a three-phase motor according to claim 1, characterized in that: The three-phase rectifier-step-down circuit consists of three rectifier circuits and one step-down circuit. The three rectifier circuits are composed of diodes D1, D2, and D3, respectively. The three-phase AC inputs U, V, and W are connected to the positive terminals of diodes D1, D2, and D3, respectively. The negative terminals of diodes D1, D2, and D3 are connected together. The step-down circuit includes resistors R4, R5, and R21. One end of resistors R4, R5, and R21 is connected in series to the negative terminal of diode D1, and the other end is connected to ground (GND). The output signal Vin is drawn from the connection between resistors R5 and R21.
3. The input phase loss detection circuit for a three-phase motor according to claim 1 or 2, characterized in that: The phase loss comparison circuit includes comparator chip U1B, resistor R9, resistor R11 and capacitor C4. Resistors R9 and R11 are connected in series, one end is grounded and the other end is connected to power supply VCC. Capacitor C4 is connected in parallel across resistor R11. A reference voltage Vref1 is formed between resistors R9 and R11 and input to pin 6 of comparator chip U1B. The output signal Vin is connected to pin 5 of the comparator chip U1B, and pin 7 of the comparator chip U1B outputs the phase loss signal A1.
4. The input phase loss detection circuit for a three-phase motor according to claim 3, characterized in that: A voltage regulator circuit is also provided between the output signal Vin and pin 5 of the comparator chip U1B. The voltage regulator circuit includes a resistor R10, a capacitor C3 and a clamping diode D4. One end of the resistor R10 and capacitor C3 connected in parallel is connected to the output signal Vin, and the other end is grounded to GND. One end of the clamping diode D4 is connected to the power supply VCC, and the other end is grounded to GND. The middle lead of the clamping diode D4 is connected to the output signal Vin.
5. The input phase loss detection circuit for a three-phase motor according to claim 3, characterized in that: The undervoltage comparator circuit includes comparator chip U2B, resistors R15, R19, and R20, capacitors C6 and C8, and diode D5. The output signal Vin is connected to pin 5 of comparator chip U2B through resistor R15. Resistors R19 and R20 are connected in series, with one end grounded and the other end connected to power supply VCC. Capacitor C8 is connected in parallel across resistor R20. A reference voltage Vref2 is formed between resistors R19 and R20 and input to pin 6 of comparator chip U2B. The two ends of capacitor C6 are connected to pin 5 of comparator chip U2B and ground GND, respectively. Diode D5 is connected in parallel across capacitor C6. Pin 7 of comparator chip U2B outputs the undervoltage signal B1.
6. The input phase loss detection circuit for a three-phase motor according to claim 5, characterized in that: The signal isolation processing circuit includes resistors R2, R6, R7, R1, R3, and R8, capacitors C2 and C1, transistor Q1, and optocoupler BR1.
7. The input phase loss detection circuit for a three-phase motor according to claim 6, characterized in that: Signal isolation processing circuit 2 includes resistors R13, R16, R17, R12, R14, and R18, capacitors C7 and C5, transistor Q2, and optocoupler BR2.
8. The input phase loss detection circuit for a three-phase motor according to claim 7, characterized in that: The microprocessor uses a single-chip microcomputer (MCU). The MCU determines the status of the three-phase AC inputs U, V, and W based on the received undervoltage signal B1 and phase loss signal A1.
9. A motor controller, comprising a microprocessor, an inverter circuit, and an input phase loss detection circuit for a three-phase motor, wherein the output terminal of the input phase loss detection circuit for the three-phase motor is connected to the input terminal of the microprocessor, and the microprocessor controls the operation of the inverter circuit, characterized in that: The input phase loss detection circuit of the three-phase motor adopts the input phase loss detection circuit of the three-phase motor as described in any one of claims 1 to 8.