A method for detecting open-phase of an electric drive system, a controller and a storage medium
Patent Information
- Application Number
- CN202610374665.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-25
- Publication Date
- 2026-06-16
Smart Images
Figure CN122218329A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electric motor control technology, and relates to phase loss detection, specifically to a phase loss detection method, controller and storage medium for an electric drive system. Background Technology
[0002] The electric drive system is the core power source of new energy vehicles, and its safe and stable operation is crucial. Phase loss (i.e., abnormal connection of one or more phases in the three-phase winding of the motor) is a common and serious fault. If a phase is lost during operation, it will lead to motor torque imbalance, increased vibration, and abnormal current concentration in the normal phase, causing local overheating of the motor windings, insulation aging, and even permanent damage to the insulated gate bipolar transistors (IGBTs) in the inverter due to overcurrent, resulting in high maintenance costs and safety risks.
[0003] Currently, most existing phase loss detection methods rely on current or voltage signals during motor operation for diagnosis, which cannot identify connectivity faults before vehicle startup, potentially leading to the system operating with a fault. Furthermore, detection during motor operation is susceptible to interference from load and speed changes, with sensitivity decreasing and reliability insufficient at light loads or low speeds; while some simple continuity tests lack rigorous timing control and anti-crosstalk design, easily resulting in misjudgments.
[0004] Therefore, with the increasing demands on the safety and reliability of electric drive systems in new energy vehicles, developing a phase loss detection method that can quickly, accurately, and deeply coordinate with the overall vehicle safety status after the system is powered on and before the vehicle is driven, in order to achieve early prevention of faults, is a technical problem that those skilled in the art hope to solve. Summary of the Invention
[0005] In view of the above-mentioned shortcomings of the existing technology, the purpose of this invention is to provide a method, controller and storage medium for detecting phase loss in an electric drive system. This invention can quickly, accurately and safely complete the detection of the three-phase connection status after the vehicle is powered on and before driving begins, thereby providing early warning and protection before a fault occurs, and improving the reliability and safety of the electric drive system.
[0006] The technical solution of this invention is implemented as follows:
[0007] A method for detecting phase loss in an electric drive system, specifically including the following steps:
[0008] S1: Determine whether the electric drive system meets the prerequisites for performing phase loss detection;
[0009] S2: If the aforementioned preconditions are met, the controller applies pulse voltages to the U-phase, V-phase, and W-phase of the motor in a preset order; simultaneously, it periodically detects the current response of the corresponding detection phase.
[0010] S3: Based on the current response, determine whether there is a phase loss fault in the detected phase;
[0011] S4: If none of the three phases have a phase loss fault, the electric drive system is determined to be without a phase loss; otherwise, if any one phase has a phase loss fault, the electric drive system is determined to be without a phase.
[0012] Furthermore, in step S1, the preconditions include:
[0013] The electric drive system controller initialization is complete;
[0014] The electric drive system does not have faults that limit current output or turn off the power transistor;
[0015] The current sensor has completed zero-drift calibration;
[0016] The vehicle's high-voltage relays are closed;
[0017] The bus voltage is greater than the first preset voltage threshold.
[0018] The motor speed is less than the preset speed threshold.
[0019] Furthermore, in step S2, the specific method for applying pulse voltages to the U-phase, V-phase, and W-phase of the motor in a preset order is as follows:
[0020] First, a pulse voltage is applied to phase U, and after phase U detection is completed and a first preset delay is waited, a pulse voltage is applied to phase V.
[0021] After completing the V-phase detection and waiting for the second preset delay, a pulse voltage is applied to the W-phase.
[0022] The first preset delay and the second preset delay are used to reduce the current generated by the previous phase detection to zero, so as to avoid electrical crosstalk to the detection of subsequent phases.
[0023] Furthermore, in step S2, the specific method for periodically detecting the current response is as follows:
[0024] The current value of the detection phase is repeatedly collected at a fixed sampling period until a valid current value is collected or the preset total detection time is reached.
[0025] Furthermore, in step S3, the logic for determining whether a phase loss fault exists in the detection phase is as follows:
[0026] Within a single sampling period, if the current value of the detected phase is greater than the first current threshold, and the absolute current values of the other two phases are both less than the second current threshold, then the current detection of the detected phase is deemed to have passed.
[0027] If the current detection of a particular phase fails to pass within the total detection time, then the phase in question is deemed to have a phase loss fault.
[0028] Furthermore, the first current threshold i(t) is dynamically calculated from the applied pulse voltage and the motor inductance parameters, and its calculation formula is as follows:
[0029]
[0030] In the formula, V is the applied pulse voltage, V; L is the inductance of the motor, H; t is the current time from the moment the pulse voltage is applied, s.
[0031] The present invention also provides an electric drive system controller, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the electric drive system phase loss detection method described above.
[0032] The present invention also provides a storage medium storing a computer program that, when executed by a processor, implements the aforementioned method for detecting phase loss in an electric drive system.
[0033] Compared with the prior art, the present invention has the following beneficial effects:
[0034] 1. This invention can accurately identify connection phase loss faults before the motor starts, fundamentally eliminating the possibility of "operating with defects", thus enabling early warning and protection before the fault occurs, and improving the reliability and safety of the electric drive system.
[0035] 2. This invention applies independent pulse voltages sequentially to the U, V, and W phases of the electric drive system when the vehicle is static, and eliminates inter-phase crosstalk through preset delays, ensuring the independence and accuracy of each phase detection. Simultaneously, based on the motor inductance parameters and the applied pulse voltage, the current judgment threshold is calculated in real time, allowing the detection standard to adapt to different motor models and system states. This effectively avoids missed or false detections caused by fixed thresholds under light load, low speed, or parameter differences, significantly improving the accuracy and robustness of phase loss identification.
[0036] 3. This invention ensures that the phase loss detection action is performed only within a safe and controllable "time window" by setting preconditions, preventing secondary risks that may arise from detection under unstable conditions. This method can pre-identify phase loss faults before the vehicle starts and immediately trigger protection mechanisms (such as prohibiting starting or reducing power operation), thereby proactively avoiding hardware damage such as motor overheating and IGBT breakdown caused by phase loss operation. This significantly improves the intrinsic safety level of the electric drive system and provides key technical support for meeting the fault prevention and safety monitoring requirements of automotive functional safety standards such as ISO 26262.
[0037] 4. This invention does not rely on a specific hardware platform and can be implemented in existing electric drive controllers via software, making it easy to integrate and promote. By preventing serious hardware failures in advance, it can effectively reduce unplanned downtime, high-cost repairs, and replacement of core components caused by phase loss problems, significantly reducing user operating costs and the after-sales maintenance burden on manufacturers. Attached Figure Description
[0038] Figure 1 -Flowchart of the phase loss detection method of the present invention. Detailed Implementation
[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.
[0040] Since the electric drive system is the core power source of new energy vehicles, its safe and stable operation is crucial. Phase loss (i.e., abnormal connection of one or more phases in the three-phase windings of the motor) is a common and serious fault. If a phase is lost, it will lead to motor torque imbalance, increased vibration, and abnormal current concentration in the normal phases, causing localized overheating of the motor windings, insulation aging, and even permanent damage to the insulated-gate bipolar transistors (IGBTs) in the inverter due to overcurrent, resulting in high maintenance costs and safety risks. However, most existing phase loss detection methods rely on current or voltage signals during motor operation for diagnosis, failing to identify connectivity faults before vehicle startup, potentially leading to the system operating with a defect. Furthermore, detection during motor operation is susceptible to interference from load and speed changes, with decreased sensitivity and insufficient reliability under light load or low speed; and some simple continuity tests lack rigorous timing control and anti-crosstalk design, easily leading to misjudgments.
[0041] Based on this, the present invention provides a method for detecting phase loss in an electric drive system, the flowchart of which is as follows: Figure 1 As shown, this method is executed by the controller of the electric drive system and specifically includes the following steps:
[0042] S1: Determine whether the electric drive system meets the prerequisites for performing phase loss detection.
[0043] Before initiating phase loss detection, the controller first verifies whether a series of prerequisites to ensure the safety and effectiveness of the detection are met. These prerequisites include, but are not limited to: (1) the electric drive system controller has completed initialization; (2) the electric drive system does not have faults that limit current output or turn off power transistors; (3) the current sensor has completed zero-drift calibration; (4) the vehicle's high-voltage relay is closed; (5) the bus voltage is greater than the first preset voltage threshold; and (6) the motor speed is less than the preset speed threshold.
[0044] Electric drive system controller initialization complete: The electric drive system controller has completed power-on self-test, parameter loading, and kernel initialization.
[0045] No output limiting fault: There are currently no pending faults in the system that require limiting current output or forcibly shutting down power transistors (such as IGBTs) (such as over-temperature, over-voltage, etc.).
[0046] Sensors have been calibrated: The Hall sensors or sampling resistors used to detect three-phase current have been zero-drift calibrated to ensure the accuracy of static current readings.
[0047] High-voltage system ready: The high-voltage main relay of the vehicle has been reliably closed, and the bus voltage provided by the power battery is greater than a preset safety threshold (e.g., 200V) to ensure sufficient voltage for pulse excitation.
[0048] The motor is stationary: the absolute value of the motor speed obtained by the resolver sensor or other means is less than a preset minimum threshold (e.g., 10 rpm), ensuring that the motor rotor is basically stationary during detection and avoiding back EMF interference.
[0049] If any of the above preconditions are not met, the controller will temporarily pause the phase detection process and may record the corresponding system status. Only when all preconditions are met simultaneously will the process proceed to step S2.
[0050] S2: If the aforementioned preconditions are met, the controller applies pulse voltages to the U-phase, V-phase, and W-phase of the motor in a preset order; at the same time, it periodically detects the current response of the corresponding detection phase.
[0051] First, perform U-phase detection. Apply a pulse voltage to U-phase (the pulse voltage can be adjusted as needed, such as 30V), and collect the current value of U-phase at a fixed sampling period (such as 100us) until a valid current value is collected or the preset total detection time (such as 1ms) is reached, which indicates that U-phase detection is complete.
[0052] After the U-phase detection is completed, wait for the first preset delay (e.g., 500µs) to allow the current generated during the U-phase detection to decay to zero, thus avoiding electrical crosstalk and misjudgment caused by its residual current to the V-phase detection.
[0053] Then, V-phase detection is performed. First, a pulse voltage is applied to V-phase, and the current value of V-phase is collected at a fixed sampling period until a valid current value is collected or the preset total detection time is reached, which indicates that V-phase detection is complete.
[0054] After the V-phase detection is completed, wait for the first preset delay to allow the current generated during the V-phase detection to decay to zero, so as to avoid electrical crosstalk and misjudgment caused by its residual current to the W-phase detection.
[0055] Then, W-phase detection is performed. First, a pulse voltage is applied to W-phase, and the current value of W-phase is collected at a fixed sampling period (e.g., 100us) until a valid current value is collected or the preset total detection time is reached, which indicates that the W-phase detection is complete.
[0056] S3: Based on the current response, determine whether there is a phase loss fault in the detected phase.
[0057] Within a single sampling period, if the current value of the detected phase is greater than the first current threshold, and the absolute values of the currents of the other two phases are both less than the second current threshold, then the current detection of that detected phase is considered successful. If the current detection of that detected phase fails to pass within the total detection time, then a phase loss fault is determined to exist in that detected phase. Here, the first current threshold is a dynamically calculated time-varying threshold, while the second current threshold is a set value (e.g., 0.5A) to ensure that there is no significant current in the non-detected phases due to mutual inductance or noise, thus guaranteeing the independence of the detection. The first current threshold is dynamically calculated from the applied pulse voltage amplitude and the motor phase inductance parameters, and its calculation formula is as follows:
[0058]
[0059] Where V is the amplitude of the applied pulse voltage, V; L is the inductance of the motor, H; t is the current time, s, calculated from the moment the pulse voltage is applied.
[0060] For example, when t=50us, V=30V, L=0.5mH, then i(t)=(30 / 0.0005)*0.00005=3A.
[0061] S4: If none of the three phases have a phase loss fault, the electric drive system is determined to be without a phase loss; otherwise, if any one phase has a phase loss fault, the electric drive system is determined to be without a phase.
[0062] If the current detection of all three phases passes, meaning there is no phase loss fault, it indicates that the electric drive system is functioning normally and can report to the vehicle controller via communication methods such as the CAN bus.
[0063] If the current detection of any one phase fails—that is, if only one phase current detection fails, or even two or three phase current detections fail—it indicates a phase loss in the electric drive system, and the faulty phase can be identified, such as the U-phase being missing. Simultaneously, the controller should immediately trigger the corresponding protection mechanism, such as locking the drive output to prevent the motor from starting; or, under certain fault-tolerant strategies, entering a reduced-power operation mode and illuminating the instrument panel fault indicator light to prompt the driver to check.
[0064] The present invention also provides an electric drive system controller for implementing the above-mentioned phase loss detection method. The controller is usually a motor controller (MCU) for new energy vehicles, and its hardware structure includes, but is not limited to: microprocessor (such as ARM Cortex-M or Infineon AURIX series multi-core MCU), memory (Flash, RAM), analog-to-digital converter (ADC), gate drive circuit, communication interface (CAN, SPI), etc.
[0065] The memory stores a computer program containing all the instructions for executing the phase loss detection method of the electric drive system described above. When the microprocessor (processor) runs the program, it can sequentially execute operations such as precondition judgment, PWM pulse sequence generation, current sampling, dynamic threshold calculation, logical judgment, and fault reporting, thereby implementing the method described in this invention at the hardware level.
[0066] Furthermore, the present invention also provides a storage medium. This storage medium may be internal flash memory (Flash), read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk, etc., within the electric drive system controller. The storage medium stores a computer program, which, when executed by the processor in the controller, enables the implementation of the aforementioned electric drive system phase loss detection method.
[0067] Finally, it should be noted that the above embodiments of the present invention are merely illustrative examples and not intended to limit the implementation of the invention. Those skilled in the art can make other variations and modifications based on the above description. It is impossible to exhaustively list all possible implementations here. All obvious variations or modifications derived from the technical solutions of this invention are still within the scope of protection of this invention.
Claims
1. A method for detecting phase loss in an electric drive system, characterized in that, Specifically, the following steps are included: S1: Determine whether the electric drive system meets the prerequisites for performing phase loss detection; S2: If the aforementioned preconditions are met, the controller applies pulse voltages to the U-phase, V-phase, and W-phase of the motor in a preset order; simultaneously, it periodically detects the current response of the corresponding detection phase. S3: Based on the current response, determine whether there is a phase loss fault in the detected phase; S4: If none of the three phases have a phase loss fault, the electric drive system is determined to be without a phase loss; otherwise, if any one phase has a phase loss fault, the electric drive system is determined to be without a phase.
2. The method for detecting phase loss in an electric drive system according to claim 1, characterized in that, In step S1, the preconditions include: The electric drive system controller initialization is complete; The electric drive system does not have faults that limit current output or turn off the power transistor; The current sensor has completed zero-drift calibration; The vehicle's high-voltage relays are closed; The bus voltage is greater than the first preset voltage threshold. The motor speed is less than the preset speed threshold.
3. The method for detecting phase loss in an electric drive system according to claim 1, characterized in that, In step S2, the specific method for applying pulse voltages to the U-phase, V-phase, and W-phase of the motor in a preset order is as follows: First, a pulse voltage is applied to phase U, and after phase U detection is completed and the first preset delay is waited, a pulse voltage is applied to phase V. After completing the V-phase detection and waiting for the second preset delay, a pulse voltage is applied to the W-phase. The first preset delay and the second preset delay are used to reduce the current generated by the previous phase detection to zero, so as to avoid electrical crosstalk to the detection of subsequent phases.
4. A method for detecting phase loss in an electric drive system according to claim 1 or 3, characterized in that, In step S2, the specific method for periodically detecting the current response is as follows: The current value of the detection phase is repeatedly collected at a fixed sampling period until a valid current value is collected or the preset total detection time is reached.
5. The method for detecting phase loss in an electric drive system according to claim 4, characterized in that, In step S3, the logic for determining whether a phase loss fault exists in the detection phase is as follows: Within a single sampling period, if the current value of the detected phase is greater than the first current threshold, and the absolute values of the currents of the other two phases are both less than the second current threshold, then the current detection of the detected phase is deemed to have passed. If the current detection of a particular phase fails to pass within the total detection time, then the phase in question is deemed to have a phase loss fault.
6. The method for detecting phase loss in an electric drive system according to claim 5, characterized in that, The first current threshold i(t) is dynamically calculated from the applied pulse voltage and the motor inductance parameters, and its calculation formula is as follows: In the formula, V is the applied pulse voltage, V; L is the inductance of the motor, H; t is the current time from the moment the pulse voltage is applied, s.
7. An electric drive system controller, characterized in that, The system includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the phase loss detection method for an electric drive system as described in any one of claims 1-6.
8. A storage medium storing a computer program, characterized in that, When the program is executed by the processor, it implements the phase loss detection method for the electric drive system according to any one of claims 1-6.