A method for positioning open-circuit bridge arms of a variable frequency controller driving chip and a variable frequency controller
Patent Information
- Application Number
- CN202611194897.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-07
- Publication Date
- 2026-10-30
AI Technical Summary
[0009]本发明目的在于提供一种变频控制器驱动芯片开路桥臂定位方法及变频控制器，针对现有变频控制器中三个半桥驱动芯片发生开路失效时，无法低成本、高效率地精确定位具体是哪一个桥臂失效的问题，提供一种利用FOC开环定位阶段的相电流正负半周积分面积分析，实现驱动芯片开路失效精确桥臂定位的方法
[0026]1.零硬件成本与零时间开销：无需新增任何传感器（如退饱和检测电路、门极电压采样单元）或专用诊断硬件；完全复用系统已有的电流采样通道与FOC开环定位流程。故障检测与电机初始位置估算并行执行，不额外增加启动时间，真正实现软件升级即生效。
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Figure CN123019568A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of frequency converter and power electronic control technology, and more specifically, to a method for positioning the open-circuit bridge arm of a frequency converter driver chip and a frequency converter controller. Background Technology
[0002] In the field of variable frequency control for new energy vehicles, vector control of permanent magnet synchronous motors (PMSMs) is the core technology for achieving efficient drive. Its power conversion stage typically consists of a three-phase bridge inverter circuit composed of three half-bridge driver chips and six insulated-gate bipolar transistors (IGBTs). Each driver chip receives the pulse-width modulation (PWM) logic level output from the microcontroller unit (MCU) and converts it into a gate voltage sufficient to drive the IGBT to turn on or off. Specifically, a driver chip includes two input terminals and two output terminals, used to independently control the upper and lower IGBTs of the same phase bridge arm, respectively.
[0003] However, as a critical component in power electronic systems, driver chips operate under harsh environments of high temperature, high pressure, strong vibration, and frequent on / off cycles, making their internal output stage circuits highly susceptible to damage. The most common failure mode for driver chips is an open-circuit output. Once this type of fault occurs, the driver chip cannot transmit the PWM signal to the corresponding IGBT gate, causing the IGBT to remain in the off state. This directly results in the corresponding bridge arm failing to conduct properly, leading to serious consequences such as single-phase operation of the motor, torque fluctuations, or even system shutdown. Therefore, quickly and accurately locating open-circuit faults in driver chips is crucial for ensuring system safety and guiding maintenance.
[0004] Existing technical solutions for detecting open-circuit failures in driver chips have the following main shortcomings:
[0005] 1. High hardware cost and complex layout: Some existing solutions rely on additional hardware diagnostic circuits for fault detection, such as gate-emitter voltage monitoring circuits and desaturation detection circuits. These solutions require the addition of comparators, optocouplers, or isolation operational amplifiers to the system. This not only significantly increases the material cost of the system but also increases the layout complexity of the printed circuit board, which is not conducive to miniaturization and low-cost design.
[0006] 2. Complex Algorithms and High False Positive Rate: Another approach attempts to extract fault features during normal motor operation using complex current signal processing algorithms (such as the current averaging method and the Park vector method). These methods typically require setting complex adaptive thresholds under different speeds and load conditions, resulting in high algorithm development difficulty and long debugging cycles. Furthermore, under low-speed and light-load conditions, due to the weak current signal, existing technologies are prone to false positives or false negatives due to noise interference, making it difficult to meet high reliability requirements.
[0007] 3. Lack of low-cost, precise fault location methods utilizing the startup phase: Most existing detection methods fail to fully utilize the inherent processes of the system startup phase. In particular, there is a lack of a simple method that can precisely pinpoint whether the fault lies in the upper or lower bridge arm driver chip, using only the inherent data from system startup without incurring additional time overhead. Existing fuzzy diagnostic methods often only identify a fault in a single phase, failing to distinguish the specific bridge arm, which complicates subsequent repair and replacement, and prolongs troubleshooting time.
[0008] Therefore, there is a need for a method for locating open-circuit bridge arms of a frequency converter driver chip and a frequency converter controller that can utilize the inherent phase current sampling data during the open-loop positioning process of the field-oriented control (FOC) in the startup phase of the frequency converter to accurately locate the open-circuit failure of the driver chip without increasing any additional hardware costs or occupying any additional time window, and can clearly distinguish the specific fault locations of the upper and lower bridge arms. Summary of the Invention
[0009] The purpose of this invention is to provide a method for locating open-circuit bridge arms of a frequency converter driver chip and a frequency converter controller. Addressing the problem that existing frequency converter controllers cannot accurately locate which bridge arm failed when three half-bridge driver chips experience open-circuit failure in a cost-effective and efficient manner, this invention provides a method for accurately locating the bridge arm of a driver chip in open-circuit failure by utilizing the integral area analysis of the positive and negative half-cycles of the phase current during the FOC open-loop positioning stage.
[0010] To achieve the above objectives, this invention provides a method for positioning the open-circuit bridge arm of a frequency converter controller driver chip and a frequency converter controller. The technical solution of this invention is implemented as follows:
[0011] A method for locating the open-circuit bridge arm of a frequency converter controller driver chip includes the following steps:
[0012] S1. During the open-loop positioning stage of the magnetic field orientation control, a rotating voltage vector is applied to the frequency converter to make sinusoidal phase current flow through the three-phase coil;
[0013] S2. In each pulse width modulation control cycle, the instantaneous phase current of the three phases is collected, and the positive and negative components of each phase current are independently integrated and accumulated.
[0014] S3. When the integral accumulation process reaches the predetermined electrical angle, the accumulation is stopped, and the positive integral accumulation value and negative integral accumulation value of each phase are compared with the preset drive open circuit detection threshold.
[0015] S4. Based on the comparison results, determine the specific open bridge arm and generate the corresponding fault flag bit.
[0016] In step S2, the integration accumulation process includes: if the instantaneous current value of a certain phase is greater than or equal to zero, the instantaneous current value is accumulated to the positive integration accumulator of that phase; if the instantaneous current value of a certain phase is less than zero, the absolute value of the instantaneous current value is accumulated to the negative integration accumulator of that phase.
[0017] In step S3, the predetermined electrical angle is greater than or equal to 180° and less than or equal to 720°.
[0018] In step S3, the method for obtaining the drive open circuit detection threshold includes: acquiring the noise floor signal of the phase current sampling channel when the motor is not powered on and all drive chips are working normally; performing independent integration and accumulation processing on the positive and negative components of each phase current of the noise floor signal to obtain the noise floor integral value; multiplying the noise floor integral value by a preset safety factor to obtain the value as the drive open circuit detection threshold.
[0019] Furthermore, the preset safety factor ranges from 200% to 500%.
[0020] In step S4, the determination logic is as follows: if the positive integral accumulation value of a certain phase is less than the preset open-circuit detection threshold, then the upper bridge arm driver chip of that phase is determined to have an open-circuit failure; if the absolute value of the negative integral accumulation value of a certain phase is less than the preset open-circuit detection threshold, then the lower bridge arm driver chip of that phase is determined to have an open-circuit failure.
[0021] It also includes step S5: when step S4 determines that any one of the driver chips is open-circuited, all pulse width modulation output signals are immediately blocked, so that the system enters a fault-safe state; and a fault code containing specific open-circuit bridge arm information is reported through the communication bus.
[0022] In step S1, the rotating voltage vector is a reference value of the perpendicular and perpendicular axis voltage with a known amplitude, and the rotor angle is continuously accumulated at a preset electric angular velocity.
[0023] In step S2, the peak current value of each phase current during the positive and negative half-cycles is also tracked and recorded, and the peak current value is compared with the peak reference value of historical normal operation as an auxiliary verification condition.
[0024] A frequency converter includes a main control chip, three half-bridge drive chips, a three-phase bridge inverter circuit composed of six IGBTs, and a phase current sampling circuit. The main control chip stores a computer program, and when the program is run, it executes the open-circuit bridge arm positioning method of the frequency converter drive chip as described above.
[0025] Compared with existing technologies, the open-circuit bridge arm positioning method for a frequency converter driver chip and the frequency converter controller described in this invention have the following advantages:
[0026] 1. Zero hardware cost and zero time overhead: No new sensors (such as desaturation detection circuits or gate voltage sampling units) or dedicated diagnostic hardware are required; the existing current sampling channel and FOC open-loop positioning process of the system are fully reused. Fault detection and motor initial position estimation are performed in parallel without adding extra startup time, truly achieving immediate effect upon software upgrade.
[0027] 2. High anti-interference capability and easy engineering calibration: The adaptive threshold mechanism based on the system's own noise floor is adopted, which avoids the complex modeling of traditional methods that rely on motor parameters (such as inductance and resistance), operating conditions (speed and load) or require a large number of calibration curves. This significantly improves the robustness of the algorithm and its cross-platform portability, and greatly reduces the difficulty of mass production calibration and production line debugging.
[0028] 3. Physical-level precise bridge arm differentiation capability: By independently integrating the positive and negative components of the three-phase current, the system directly maps the conduction energy contribution of the upper and lower bridge arms. When the positive integral of a phase is significantly lower than a threshold, it indicates that the driver chip of the corresponding upper bridge arm is open; when the absolute value of the negative integral is lower than a threshold, it clearly points to an open circuit in the lower bridge arm of that phase. This method is based on the essential characteristics of the physical flow of current, eliminating the need for table lookups and secondary logical deductions, and achieving one-step precise location of the fault point from an anomaly in a phase to a specific bridge arm device. Attached Figure Description
[0029] Figure 1 This is a schematic diagram of the overall process of the driver chip open-circuit failure location method of the present invention as described in Embodiment 1 of the present invention;
[0030] Figure 2 This is a schematic diagram of the connection topology of the main circuit and drive chip of the frequency converter controller according to Embodiment 2 of the present invention;
[0031] Figure 3 This is a diagram of the normal operating waveform (complete positive and negative half-cycles) of the driver chip described in Embodiment 1 of the present invention;
[0032] Figure 4 This is a waveform diagram of the open circuit of the upper arm drive (negative half cycle only) as described in Embodiment 1 of the present invention;
[0033] Figure 5 This is a waveform diagram of the open circuit of the upper arm drive (positive half cycle only) as described in Embodiment 1 of the present invention. Detailed Implementation
[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the described embodiments are only some, not all, of the embodiments of this invention. The specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.
[0035] Example 1
[0036] This embodiment provides a method for accurately locating open-circuit failures of drive chips in the frequency converter controller of permanent magnet synchronous motors (PMSMs) for new energy vehicles. This method utilizes the inherent open-loop location stage in the field-oriented control (FOC) algorithm. By collecting and analyzing the integral areas of the positive and negative half-cycles of the three-phase currents, it achieves precise location of which specific drive chip among the six bridge arms (A_H, A_L, B_H, B_L, C_H, C_L) has experienced an open-circuit failure without increasing any additional hardware costs.
[0037] like Figure 1 As shown, the specific implementation steps of this embodiment are as follows:
[0038] S1. Enter the FOC open-loop positioning stage and apply the rotating voltage vector:
[0039] After the frequency converter starts, the system automatically enters the FOC open-loop positioning (Location) stage of the PMSM motor. This stage is an inherent process before motor startup and is used to achieve initial rotor position alignment.
[0040] S11. The controller forcibly applies known amplitude AC and DC axis voltage reference values (Id_ref, Iq_ref) and sets the electrical angular velocity (LOCATION_OMEGA).
[0041] S12. The controller continuously accumulates the rotor angle, causing the motor rotor to rotate at a preset speed in open-loop mode.
[0042] During this process, the inverter's three-phase bridge arm outputs a sinusoidal voltage waveform corresponding to the rotation angle, forcing the three-phase coils to flow sinusoidal phase currents of corresponding amplitude. Regardless of whether the driver chip is faulty, as long as a conduction loop exists in the circuit, the current waveform will exhibit specific positive and negative half-cycle characteristics. For example... Figure 3As shown, this is the ideal waveform of the current in a certain phase (e.g., phase A) during the open-loop positioning stage when all three-phase inverter drive chips are working normally. This waveform has complete positive and negative half-cycles, corresponding to the symmetrical current response generated by the alternating conduction of the upper and lower bridge arms; both the positive integral accumulation value (PosSum) and the negative integral accumulation value (NegSum) are significantly greater than the noise floor integral threshold, indicating that the drive function of the upper and lower bridge arms of this phase is intact.
[0043] If a bridge arm is open-circuited, the corresponding half-cycle current will be missing or will only be background noise, providing a physical signal basis for subsequent diagnosis. For example... Figure 4 and Figure 5 As shown. Figure 4 This represents a typical current waveform when the driver chip of the upper bridge arm of a certain phase (such as phase A) experiences an open-circuit failure. At this time, the upper bridge arm cannot conduct, and only the lower bridge arm can respond to the PWM signal, resulting in the current of that phase having only a negative half-cycle (i.e., a current pulse flowing to the negative terminal of the power supply), while the positive half-cycle is missing or close to zero. Figure 5 This represents a typical current waveform when the lower bridge arm driver chip of a certain phase (such as phase A) experiences an open-circuit failure. At this time, the lower bridge arm cannot conduct, and only the upper bridge arm can respond to the PWM signal, resulting in the current of that phase having only a negative half-cycle (i.e., a current pulse flowing to the positive terminal of the power supply), while the negative half-cycle is missing or close to zero.
[0044] S2. Real-time acquisition of three-phase current and integration accumulation of positive and negative half-cycles:
[0045] In the interrupt service routine of each PWM control cycle, the following data acquisition and processing logic is executed:
[0046] S21. Real-time acquisition of three-phase instantaneous phase current (I) via a dual-resistor sampling circuit. a I b I c ).
[0047] S22. For each phase current, initialize the positive integral accumulator (stIabcPosSum) and the negative integral accumulator (stIabcNegSum) respectively.
[0048] S23. Determine the polarity of the current instantaneous current value:
[0049] If the instantaneous current value is greater than or equal to zero (positive half-cycle), the instantaneous current value is accumulated to the positive integrator of that phase, and the positive peak current during that time period is tracked and recorded.
[0050] If the instantaneous current value is less than zero (negative half-cycle), the absolute value of the instantaneous current value is accumulated to the negative integrator of that phase, and the negative peak current during that time period is tracked and recorded.
[0051] This step uses the "integral area method" instead of the traditional instantaneous amplitude comparison method. Because the integration process naturally provides low-pass filtering for high-frequency noise and accumulates half a cycle's energy information, it effectively avoids misjudgments caused by excessively low instantaneous values near the zero-crossing point of the current waveform, significantly improving anti-interference capabilities. Simultaneously, independently accumulating the positive and negative half-cycles provides a data basis for distinguishing between upper and lower bridge arm faults.
[0052] In addition, the peak current value of each phase current during the positive and negative half-cycles is tracked and recorded simultaneously, and the peak current value is compared with the peak reference value of historical normal operation, which can be used as an auxiliary verification condition.
[0053] S3. After reaching the predetermined electrical angle, the integral data is transferred and the accumulator is reset. The positive and negative integral accumulation values of each phase are compared with the preset drive open circuit detection threshold.
[0054] S31. Monitor the cumulative electrical angle of the open-loop positioning. When the cumulative angle reaches a predetermined electrical angle, determine that a complete positioning detection cycle has ended and stop accumulating. The predetermined electrical angle is greater than or equal to 180° and less than or equal to 720°, preferably 360°.
[0055] S32. Transfer the positive integral accumulation value (PosSum) and negative integral accumulation value (NegSum) of each phase from the temporary register to the integration result structure for subsequent determination.
[0056] S33. After the transfer is completed, immediately clear all temporary accumulators to prepare for the next round of testing.
[0057] By utilizing the inherent process of system startup to complete a full electrical cycle scan, there is no need to schedule a separate detection time window, achieving seamless integration of fault diagnosis and motor startup process without adding extra system time overhead.
[0058] S34. Driver open circuit detection threshold calibration:
[0059] When the motor is not powered on and all drive chips are working normally (inverter has no output), the noise floor signal of the phase current sampling channel is pre-acquired. The positive and negative components of each phase current in the noise floor signal are independently integrated and accumulated (same as step S2) to obtain the noise floor integral value. The noise floor integral value is multiplied by a preset safety factor, and the resulting value is the drive open-circuit detection threshold (PROTECT_PHASE_LOSS_STARTUP_THRESHOLD). The preset safety factor ranges from 200% to 500%, preferably 300%.
[0060] The drive open circuit detection threshold is determined entirely based on the system's own noise floor level and is independent of external conditions such as motor parameters and bus voltage fluctuations. It has good universality and portability and can effectively distinguish between normal current integral and abnormal states containing only noise floor.
[0061] S4. Determine the specific open-circuit bridge arm based on the comparison between the integral value and the preset open-circuit detection threshold:
[0062] Read the phase data from the integral result structure and perform the following logical judgment:
[0063] S41. Upper arm fault determination. If the positive integral cumulative value of a certain phase (e.g., phase A) is less than the preset drive open circuit detection threshold, it indicates that there is no effective current flowing in that phase during the positive half-cycle. It is determined that the upper arm drive chip (A_H) of that phase has an open circuit failure, and the fault flag bit (HW_ERR_DRV_A_H) is set.
[0064] S42. Lower arm fault determination. If the absolute value of the negative integral accumulation of a certain phase (e.g., phase A) is less than the preset threshold, it indicates that there is no effective current flowing in that phase during the negative half-cycle. It is determined that the lower arm driver chip (A_L) of that phase has an open circuit failure, and the fault flag bit (HW_ERR_DRV_A_L) is set.
[0065] S43. Similarly, perform the above positive and negative threshold comparisons on phase B and phase C respectively to determine whether there is an open circuit failure in the upper / lower arm of phase B and the upper / lower arm of phase C.
[0066] This step can accurately distinguish which specific bridge arm the fault occurred in (a total of 6 possible locations), solving the problem that existing technologies can only generally determine "phase loss" but cannot locate specific components, and providing clear replacement guidance for maintenance personnel.
[0067] S5. Report fault information and execute safety protection actions:
[0068] S51. If it is determined in step S4 that any drive chip is open-circuited, immediately block all PWM outputs, cut off the inverter drive signal, and put the system into a fault-safe state to prevent equipment damage caused by IGBT shoot-through or false turn-through.
[0069] S52. Report fault information containing specific fault codes via a communication bus (such as a CAN bus), including one or more of A_H, A_L, B_H, B_L, C_H, and C_L, to guide maintenance personnel to quickly replace faulty components.
[0070] This step enables immediate isolation and accurate reporting of faults, ensuring system security while shortening troubleshooting time and improving after-sales maintenance efficiency.
[0071] In summary, this embodiment, through steps S1 to S5, completely reuses the existing phase current sampling circuit without adding additional hardware diagnostic circuits, gate-emitter voltage monitoring circuits, or desaturation detection circuits. It successfully realizes a driver chip open-circuit failure detection method with zero hardware cost, no time overhead, strong anti-interference capability, and the ability to accurately locate specific bridge arms.
[0072] Example 2
[0073] This embodiment provides a hardware structure for a new energy vehicle frequency converter controller, used to execute the method for accurately locating open-circuit failure of the drive chip described in Embodiment 1.
[0074] like Figure 2 As shown, the frequency converter includes the following core components:
[0075] The main control chip (MCU control unit) includes an ADC analog-to-digital converter, a PWM timer, and FOC control algorithm firmware. The FOC control algorithm firmware includes a register structure for storing integral data and a logic module for setting fault flags. The main control chip stores and runs the computer program described herein, responsible for executing all steps S1 to S5, including generating rotating voltage commands, acquiring current, performing positive and negative half-cycle integral accumulation, threshold comparison and judgment, and fault protection.
[0076] Three half-bridge driver chips: Driver Chip 1, Driver Chip 2, and Driver Chip 3. Each driver chip receives two PWM signals (such as PWM0 / PWM1, PWM2 / PWM3, PWM4 / PWM5) from the MCU, performs level conversion, isolation, and amplification, and then drives the corresponding upper and lower bridge arm IGBTs (such as U-phase upper / lower bridge IGBT, V-phase upper / lower bridge IGBT, W-phase upper / lower bridge IGBT). When any one of the driver chips fails with an open circuit, its corresponding two output channels will have no driving capability.
[0077] A three-phase bridge inverter circuit composed of six IGBTs forms the three-phase main power circuits (U, V, and W). Each phase includes one upper bridge arm IGBT (e.g., the upper bridge IGBT of phase U) and one lower bridge arm IGBT (e.g., the lower bridge IGBT of phase U), for a total of six IGBTs. This circuit inverts the DC bus voltage into a three-phase AC voltage, directly driving a permanent magnet synchronous motor.
[0078] Phase current sampling circuit: A dual-resistor sampling topology is adopted, that is, two sampling resistors are set at the common terminal of the lower bridge arm of the inverter (or between the U / V phases). The two-phase current is acquired in real time through the MCU's ADC channel and calculated according to Kirchhoff's current law (…). The third-phase current is calculated. This circuit provides the original current signal for this invention and is the basis for achieving zero-hardware-cost diagnostics.
[0079] The four modules described above work together to form an intelligent variable frequency controller with self-diagnostic capabilities. Its core innovation lies in the fact that the MCU control unit not only performs conventional motor control functions but also, through running a specific program, reuses the FOC open-loop positioning stage, originally used only for motor starting, as an online monitoring window for the health status of the drive chips. Therefore, this controller can accurately identify the drive status of all six bridge arms without adding any sensors, comparators, or dedicated diagnostic ICs, significantly reducing system BOM costs and design complexity while improving the reliability and maintainability of the entire vehicle's electronic control system.
[0080] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.
Claims
1. A method for positioning an open-circuit bridge arm of a frequency converter controller driver chip, characterized in that, Includes the following steps: S1. During the open-loop positioning stage of the magnetic field orientation control, a rotating voltage vector is applied to the frequency converter to make sinusoidal phase current flow through the three-phase coil; S2. In each pulse width modulation control cycle, the instantaneous phase current of the three phases is collected, and the positive and negative components of each phase current are independently integrated and accumulated. S3. When the integral accumulation process reaches the predetermined electrical angle, the accumulation is stopped, and the positive integral accumulation value and negative integral accumulation value of each phase are compared with the preset drive open circuit detection threshold. S4. Based on the comparison results, determine the specific open bridge arm and generate the corresponding fault flag bit.
2. The method according to claim 1, characterized in that, In step S2, the integration accumulation process includes: if the instantaneous current value of a certain phase is greater than or equal to zero, the instantaneous current value is accumulated to the positive integration accumulator of that phase; if the instantaneous current value of a certain phase is less than zero, the absolute value of the instantaneous current value is accumulated to the negative integration accumulator of that phase.
3. The method according to claim 1, characterized in that, In step S3, the predetermined electrical angle is greater than or equal to 180° and less than or equal to 720°.
4. The method according to claim 1, characterized in that, In step S3, the method for obtaining the drive open circuit detection threshold includes: acquiring the noise floor signal of the phase current sampling channel when the motor is not powered on and all drive chips are working normally; performing independent integration and accumulation processing on the positive and negative components of each phase current of the noise floor signal to obtain the noise floor integral value; multiplying the noise floor integral value by a preset safety factor to obtain the value as the drive open circuit detection threshold.
5. The method according to claim 4, characterized in that, The preset safety factor ranges from 200% to 500%.
6. The method according to claim 1, characterized in that, In step S4, the determination logic is as follows: if the positive integral accumulation value of a certain phase is less than the preset open-circuit detection threshold, then the upper bridge arm driver chip of that phase is determined to have an open-circuit failure; if the absolute value of the negative integral accumulation value of a certain phase is less than the preset open-circuit detection threshold, then the lower bridge arm driver chip of that phase is determined to have an open-circuit failure.
7. The method according to claim 1, characterized in that, It also includes step S5: when step S4 determines that any one of the driver chips is open-circuited, all pulse width modulation output signals are immediately blocked, so that the system enters a fault-safe state; and a fault code containing specific open-circuit bridge arm information is reported through the communication bus.
8. The method according to claim 1, characterized in that, In step S1, the rotating voltage vector is a reference value of the perpendicular and perpendicular axis voltage with a known amplitude, and the rotor angle is continuously accumulated at a preset electric angular velocity.
9. The method according to claim 1, characterized in that, In step S2, the peak current value of each phase current during the positive and negative half-cycles is also tracked and recorded, and the peak current value is compared with the peak reference value of historical normal operation as an auxiliary verification condition.
10. A frequency converter controller, comprising a main control chip, three half-bridge driver chips, a three-phase bridge inverter circuit composed of six IGBTs, and a phase current sampling circuit, characterized in that: The main control chip stores a computer program, which, when run, executes the open-circuit bridge arm positioning method of the frequency converter controller drive chip as described in any one of claims 1 to 9.