A method and system for protecting a motor controller

Abstract

This application relates to a motor controller protection method and system, belonging to the technical field of circuit protection. It includes a high-voltage sampling step: sampling the high-voltage side bus current and converting it into a voltage signal, amplifying the voltage signal into an output signal, and then judging whether the current exceeds a reference value of 1. If so, a low-level signal is output, and the signal output from the high-voltage side comparator is isolated to output a signal. A phase current sampling step: sampling the phase current and converting it into a voltage signal, converting the voltage signal into an output signal, and outputting a low-level signal when the current exceeds a reference value of 2. A judgment step: judging whether the current and phase current are equal; if they are equal to 1 and equal to 0, then it is a leakage fault, and the output is latched to 0. This application has the advantage of being able to continuously latch until the fault is cleared.

Description

Technical Field

[0001] This application relates to the technical field of circuit protection, and in particular to a method and system for protecting a motor controller. Background Technology

[0002] In water pump applications, motor controllers frequently need to handle faults caused by sudden load changes, aging wiring, and water ingress. Among these, phase-to-phase short circuits (e.g., U-phase to V-phase short circuit) and output-to-PE short circuits (e.g., U-phase to PE short circuit) are two high-risk faults. During a phase-to-phase short circuit, the faulty phase current surges instantaneously (up to 5-10 times the normal current). If power devices are not disconnected in time, core components such as IGBTs and MOSFETs can overheat and burn out. During an output-to-PE short circuit, leakage current is shunted through the PE line. This disrupts the balance between bus current and phase current. Relying solely on overcurrent protection can easily lead to misjudgments, and leakage current can pose a risk of electric shock. Therefore, the protection state must be continuously latched until the fault is cleared. Summary of the Invention

[0003] To address the shortcomings of existing technologies, one of the objectives of this application is to provide a motor controller protection method and system that has the advantage of continuously latching until the fault is cleared.

[0004] The above-mentioned objective of this application is achieved through the following technical solution: A motor controller protection method includes a high-voltage sampling step: sampling the high-voltage side bus current and recording the high-voltage side bus current... Converted to voltage signal , to voltage signal Amplified to output signal Subsequently Make a judgment when When the reference value is 1, output a low-level signal. The signal output by the high-voltage side comparator The isolated output signal is Phase current sampling steps: Sample the phase current and convert it into a voltage signal, then convert the voltage signal into an output signal. ,when When the reference value is 2, the output is low, and the output signal is... Judgment steps: For and Make a judgment, if =1, and =0, then it is a leakage fault, latch output. =0.

[0005] In a preferred embodiment, this application can be further configured to include a PE line current sampling step: acquiring the PE leakage current signal. , to transfer current on PE line Converted to voltage signal ,Will Signal amplification output is ,when When the reference value is 3, the output is low, and the output signal is: In the judgment step, when When a low level is detected, the flip-flop is set, and the output is latched. = 0.

[0006] In a preferred embodiment, this application can be further configured such that, in the decision step, for and Perform a judgment and output an overcurrent protection signal. It also includes protection steps, receiving or A low-level signal shuts off the power devices in the motor controller.

[0007] In a preferred embodiment, this application can be further configured to: sample the U-phase, V-phase, and W-phase currents during the phase current sampling step, and obtain... , , Current signal, , , Current signal converted to voltage signal , , , to voltage signal , , The signal is amplified, and the amplified signal is then combined and output as a single signal using an adder. .

[0008] In a preferred embodiment, this application can be further configured to: during the phase current sampling step, sample the low-voltage side current of the bus. Converted to voltage signal And amplify the output to .

[0009] This application also discloses a motor controller protection system, including the following modules: a high-voltage sampling module: sampling the high-voltage side bus current and recording the high-voltage side bus current... Converted to voltage signal , to voltage signal Amplified to output signal Subsequently Make a judgment when When the reference value is 1, output a low-level signal. The signal output by the high-voltage side comparator The isolated output signal is Phase current sampling module: Samples the phase current, converts it into a voltage signal, and then converts the voltage signal into an output signal. ,when When the reference value is 2, the output is low, and the output signal is... , Judgment module: for and Make a judgment, if =1, and =0, then it is a leakage fault, latch output. =0.

[0010] In a preferred embodiment, this application can be further configured to include a PE line current sampling module for acquiring PE leakage current signals. , to transfer current on PE line Converted to voltage signal ,Will Signal amplification output is ,when When the reference value is 3, the output is low, and the output signal is: In the judgment step, when When a low level is detected, the flip-flop is set, and the output is latched. = 0.

[0011] In a preferred example, this application can be further configured such that, in the judgment module, for and Perform a judgment and output an overcurrent protection signal. It also includes a protection module that receives... or A low-level signal shuts off the power devices in the motor controller.

[0012] This application has the following advantages: When performing leakage protection, latching is used to reduce the probability of secondary faults. At the same time, by distinguishing between "phase short circuit" and "relative PE short circuit", timely protection can be provided when leakage occurs. Through isolation settings, the probability of false triggering is reduced. Attached Figure Description

[0013] Figure 1 This is a circuit diagram of this application.

[0014] Figure 2 This is a schematic diagram of the high-voltage side current detection of the busbar in this application.

[0015] Figure 3 This is a schematic diagram of the low-voltage side current of the busbar in another embodiment of this application.

[0016] Figure 4This is a schematic diagram of the system in this application.

[0017] Figure 5 This is a flowchart illustrating the application process. Detailed Implementation

[0018] The following is in conjunction with the appendix Figure 1 - Appendix Figure 5 This application will be described in further detail.

[0019] This application discloses a motor controller protection method, including the following steps: High-voltage sampling steps: Sample the high-voltage side bus current and record the high-voltage side bus current. Converted to voltage signal , to voltage signal Amplified to output signal Subsequently Make a judgment when When the reference value is 1, output a low-level signal. The signal output by the high-voltage side comparator The isolated output signal is ; Phase current sampling steps: Sample the currents of phase U, phase V, and phase W to obtain... , , Current signal, , , Current signal converted to voltage signal , , , to voltage signal , , The signal is amplified, and the amplified signal is then combined and output as a single signal using an adder. ,when When the reference value is 2, the output is low, and the output signal is... ; PE line current sampling steps: Acquire PE leakage current signal , to transfer current on PE line Converted to voltage signal ,Will Signal amplification output is ,when When the reference value is 3, the output is low, and the output signal is: In the judgment step, when When a low level is detected, the flip-flop is set, and the output is latched. = 0; Judgment steps: (To) and Perform a judgment and output an overcurrent protection signal. ,like =1, and =0 (when the balance is broken), it indicates a leakage fault, and the output is latched. =0; Protection steps, receiving or A low-level signal shuts off the power devices in the motor controller.

[0020] In other embodiments, during the phase current sampling step, the low-voltage side current of the bus is... Converted to voltage signal And amplify the output to .

[0021] This application also discloses a motor controller protection system, including the following modules: a high-voltage sampling module: sampling the high-voltage side bus current and recording the high-voltage side bus current... Converted to voltage signal , to voltage signal Amplified to output signal Subsequently Make a judgment when When the reference value is 1, output a low-level signal. The signal output by the high-voltage side comparator The isolated output signal is Phase current sampling module: Samples the phase current, converts it into a voltage signal, and then converts the voltage signal into an output signal. ,when When the reference value is 2, the output is low, and the output signal is... , Judgment module: for and Make a judgment, if =1, and =0, then it is a leakage fault, latch output. =0, for and Perform a judgment and output an overcurrent protection signal. .

[0022] PE line current sampling module: Acquires PE leakage current signal , to transfer current on PE line Converted to voltage signal ,Will Signal amplification output is ,when When the reference value is 3, the output is low, and the output signal is: In the judgment step, when When a low level is detected, the flip-flop is set, and the output is latched. = 0.

[0023] Protection module, receiving or A low-level signal shuts off the power devices in the motor controller.

[0024] Reference Figure 1 The controller connects to the control circuit of the actuator (motor). The rectifier bridge DB converts AC power into pulsating DC power, and the bus capacitor C converts the pulsating DC power into stable DC power. The control of the actuator (motor) is regulated by the switches of the inverter bridge Q1-Q6. Multiple sampling modules are installed on the high-current circuit, each including a sampling resistor. A leakage current auxiliary detection unit, including a feedthrough current sensor, is installed on the PE line. The following section provides further explanation of the control circuit.

[0025] The specific structure of the motor controller protection system is as follows: Busbar high-voltage side current detection unit (high-voltage sampling module) Sampling module: This module may employ, but is not limited to, high-precision alloy sampling resistors (resistance range 0.001Ω-0.05Ω, power ≥2W) or Hall current sensors, connected in series on the high-voltage side main circuit of the bus. The sampling position can be at the front or rear of the bus capacitor C, used to measure the high-voltage side bus current. Converted to voltage signal ; Signal amplification subunit: Employs operational amplifiers (including general-purpose operational amplifiers, differential operational amplifiers, and isolation amplifiers), with the input terminal connected to a voltage signal. Amplification factor A1 (adjustable), amplified output signal is ; Comparator subunit: Employs a voltage comparator (including a high-speed voltage comparator with a response time ≤2µs), with the inverting input connected to... The comparator's positive input is connected to a reference voltage source (provided by a precision reference chip), and a reference value of 1 is obtained through the reference voltage source. When the reference value is 1, output a low-level signal. ; Isolated output subunit: Employs optocouplers (including high-speed optocouplers such as 6N137, with a transmission rate ≥10Mbps and isolation voltage ≥2500Vrms) to output the signal from the high-voltage side comparator. Isolation (Logic judgment cannot be performed on the high-voltage side due to different reference grounds, so the signal is isolated before logic judgment). The output signal is... (A low level indicates that the bus current exceeds the limit), and the signal is sent to the logic judgment unit.

[0026] Phase current detection unit (phase current sampling module) Corresponding to the three phases U, V, and W, each phase has the same circuit structure: Sampling module: Not limited to using high-precision alloy sampling resistors (resistance range 0.001Ω-0.05Ω, power ≥2W) and Hall current sensors, connected in series with the U-phase, V-phase, and W-phase respectively, to collect data from the inverter bridge transistors. , , Current signal, used to convert , , Current signal converted to voltage signal , , ; Signal amplification subunit: Each phase is independently equipped with a differential operational amplifier (of the same model), with the input terminal connected to a voltage signal. , , Amplification factors A2 = A3 = A4 (amplification factors are adjustable). The three amplified signals are then superimposed and merged by an adder to output the final signal. ; Comparison subunits: Connect the inverting input of the comparator (same model), and connect reference value 2 (which can be provided through a reference chip or voltage divider) to the non-inverting input of the comparator. >Base value 2 (e.g., 1.8 times the rated current, set) When the output level is 80% or less, the output signal is low. (A low level indicates that one or more phases of UVW have excessive current.)

[0027] PE line current auxiliary detection unit (PE line current sampling module) Sampling module: Employs a through-hole current sensor, mounted on the PE input ground wire, to acquire the leakage current signal on the PE (ground wire). The through-hole current sensor outputs signals L1 and L2, which are used to measure the current on the PE line. Converted to voltage signal ; Signal amplification subunit: Employs a differential operational amplifier (including a general-purpose amplifier and an isolation amplifier, with adjustable amplification factor A1), with the input terminal connected to... The signal amplification output is ; Comparator subunit: Employs a high-speed voltage comparator (same model), with the inverting input connected to... The reference value 3 (which can be provided through a reference chip or a voltage divider) is connected to the positive input of the comparator. When the reference value is 3, the output is low, and the output signal is: (A low level indicates that the leakage current exceeds the standard), serving as an auxiliary signal for leakage current detection.

[0028] The judgment module includes a logical judgment unit. The core component is a logic chip that performs logical judgments on input signals and receives the following input signals: Busbar isolation signal ; Phase current over-limit signal ; Logical definition: Logical judgment input access and Signal: Output overcurrent protection signal and leakage protection signal ; The judgment module also includes a leakage signal latching unit. An RS flip-flop is used to perform logical judgments on the input signals, receiving the following input signals: Leakage protection signal ; (Optional) PE line current signal ; Leakage latch judgment input connection and The reset terminal R (power-on default high level) is connected to the external manual reset signal RST; when or When any one of them goes low, the flip-flop is set and the output is latched. = 0, until the RST input goes low to reset, ensuring that the leakage protection remains effective.

[0029] Protection execution unit (protection module) Buffer receive or A low-level signal shuts down the power devices of the motor controller (such as the IGBT gate drive signal) by turning off the gate drive signal output, and triggers the alarm module (indicator light / buzzer) or reports the fault to the cloud.

[0030] II. Working Principle Normal working status Current balance relationship: = + + (Ignoring minor errors, which are determined by sampling accuracy and are typically ≤5%) Signal characteristic 1: ≈ (Because the amplification factor is the same), all comparator outputs are high level. =1, =1), the output ports of the logic judgment unit are all high level ( =1, =1), the controller is operating normally.

[0031] Signal Feature 2: / A1≈ / A2+ / A3+ / A4 (different magnification) = + + It also satisfies the current balance relationship, and the comparator outputs are all high level. =1, =1), the output of the logic judgment unit is high level ( =1, =1), the controller is operating normally.

[0032] Phase-to-phase short circuit (overcurrent) protection logic Fault example: U-phase and V-phase short circuit, at this time and (W phase upper tube opening, U phase V phase lower tube opening) instantaneously increases ( =0), satisfying ≈ + (Still meets the requirement of busbar and phase current balance); Signal characteristics: Phase current comparator: =0 (output low level, indicating that at least one phase is out of control); Bus comparator: =0 (output low level, bus current exceeds the limit as phase current increases). Logical judgment: When =0 and = If a phase current exceeds the limit, it is determined to be an overcurrent fault, and the logic judgment unit outputs... =0; Protection action: The protection actuator immediately shuts down the power device, alarms with "overcurrent fault", and automatically resets after the fault is cleared (no manual reset required). At the same time, the fault is reported to the cloud. The communication method is not limited to UART, RS232, RS485, CAN, LIN.

[0033] Output relative to PE short circuit (leakage) protection logic Fault Example 1: Inverter bridge Q2, Q3, and Q4 are conducting, while Q1, Q5, and Q6 are off, resulting in a short circuit between U and PE. It is divided into two parts: one part flows back to the bus via the load ( Another portion was lost through the PE line ( = -( + + )),lead to + + < (far smaller) The balance was broken. Signal characteristics: Phase current comparator: It could be 1 (because) dramatic increase + + The trigger threshold was not reached. Output high level); Bus comparator: =0 (because) ≈ ); PE signal: =0 (leakage current exceeds the standard); Logical judgment: when =0 (bus current exceeds the limit), and =1 (when the balance is broken), (or Spe=1, i.e., when the PE auxiliary module is connected) is determined to be a leakage fault, and the logic judgment unit outputs. =0; when =1 (bus current not exceeding the limit), and =1 (when the balance is not broken), can be based on , , and Calculate the average value of the bus current. Average phase current ,like - >K1 (The difference exceeds the set threshold K1, such as 20%)* If so, it is determined to be a leakage fault; Fault Example 2: Inverter bridge Q2 is on, Q1, Q3, Q4, Q5, and Q6 are off, the negative half-cycle of the input AC U is short-circuited relative to PE, at this time... After passing through Q2, the sampling resistor R2 returns to L_1 (live wire), L_2 (live wire), and L_3 (live wire) via the rectifier bridge DB, resulting in... ≈0, ≈( + + (The balance is broken); Signal characteristics: Phase current comparator: Possibly 0 ( Output low level); Bus comparator: =1 (because) ≈0); PE signal: =0 (leakage current exceeds the standard); Logical judgment: 1. When =1 (bus current not exceeding the limit), and =0 (when the balance is broken), (or Spe=1, i.e., when the PE auxiliary module is connected) is determined to be a leakage fault, and the logic judgment unit outputs. =0; Protection action: The leakage current latching unit immediately latches the circuit. =0, the protection execution unit shuts down the power device and alarms with "leakage fault". The protection can only be released by manually resetting RST. At the same time, the fault is reported to the cloud. The communication method is not limited to UART, RS232, RS485, CAN, LIN.

[0034] In other embodiments, the phase current sampling module may also employ a low-voltage side total current detection unit, as detailed below. The current value of the series resistor on the low-voltage side of the bus corresponds to the sum of the currents of the three phases U, V, and W: Sampling module: A sampling resistor is connected in series on the low-voltage side of the bus (not limited to using a high-precision alloy sampling resistor (parameters as above) or a Hall current sensor) to measure the bus current. Converted to voltage signal ; Signal amplification subunit: Employs a differential operational amplifier (same model), with a voltage signal connected to the input. Amplification factor A6 (adjustable magnification) amplification output is ; Comparison subunits: The output is connected to the inverting input of the comparator (same model), and the reference value 2 (same as above) is connected to the positive input of the comparator. >Base value 2 (e.g., 1.8 times the rated current, set) When the output level is 80% or less, the output signal is low. (A low level indicates that one or more phases of UVW have excessive current.)

[0035] The implementation principle of this embodiment is as follows: by performing latching, the probability of causing secondary faults is reduced. At the same time, by distinguishing between "phase line short circuit" and "relative PE short circuit", timely protection can be provided when leakage occurs. Through isolation settings, the probability of false triggering is reduced.

[0036] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for protecting a motor controller, characterized in that: This includes a high-voltage sampling step: sampling the high-voltage side bus current and recording the high-voltage side bus current. Converted to voltage signal , to voltage signal Amplified to output signal Subsequently Make a judgment when When the reference value is 1, output a low-level signal. The signal output by the high-voltage side comparator The isolated output signal is ; Phase current sampling steps: Sample the phase current and convert it into a voltage signal, then convert the voltage signal into an output signal. ,when When the reference value is 2, the output is low, and the output signal is... Judgment steps: For and Make a judgment, if =1, and =0, then it is a leakage fault, latch output. =0.

2. The motor controller protection method according to claim 1, characterized in that: It also includes a PE line current sampling step: acquiring the PE leakage current signal. , to transfer current on PE line Converted to voltage signal ,Will Signal amplification output is ,when When the reference value is 3, the output is low, and the output signal is: In the judgment step, when When a low level is detected, the flip-flop is set, and the output is latched. = 0.

3. The motor controller protection method according to claim 2, characterized in that: In the decision-making step, for and Perform a judgment and output an overcurrent protection signal. It also includes protection steps, receiving or A low-level signal shuts off the power devices in the motor controller.

4. The motor controller protection method according to claim 1, characterized in that: In the phase current sampling step, the currents of phase U, phase V, and phase W are sampled to obtain... , , Current signal, , , Current signal converted to voltage signal , , , to voltage signal , , The signal is amplified, and the amplified signal is then combined and output as a single signal using an adder. .

5. The motor controller protection method according to claim 1, characterized in that: In the phase current sampling step, the low-voltage side current of the bus is... Converted to voltage signal And amplify the output to .

6. A motor controller protection system, characterized in that: Includes the following modules: High-voltage sampling module: samples the high-voltage side bus current and records the high-voltage side bus current. Converted to voltage signal , to voltage signal Amplified to output signal Subsequently Make a judgment when When the reference value is 1, output a low-level signal. The signal output by the high-voltage side comparator The isolated output signal is Phase current sampling module: Samples the phase current, converts it into a voltage signal, and then converts the voltage signal into an output signal. ,when When the reference value is 2, the output is low, and the output signal is... , Judgment module: for and Make a judgment, if =1, and =0, then it is a leakage fault, latch output. =0.

7. A motor controller protection system according to claim 6, characterized in that: It also includes a PE line current sampling module: to collect PE leakage current signals. , to transfer current on PE line Converted to voltage signal ,Will Signal amplification output is ,when When the reference value is 3, the output is low, and the output signal is: In the judgment step, when When a low level is detected, the flip-flop is set, and the output is latched. = 0.

8. A motor controller protection system according to claim 7, characterized in that: In the judgment module, for and Perform a judgment and output an overcurrent protection signal. It also includes a protection module that receives... or A low-level signal shuts off the power devices in the motor controller.

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