A current injection sampling method based on multi-timer cooperation

Abstract

The application belongs to the technical field of motor control, and specifically relates to a current injection sampling method based on cooperation of multiple timers. A PWM timer determines the duration of the action of a voltage vector in a PWM period and outputs a synchronization event; an injection timer generates a high-frequency injection voltage polarity identifier; and a sampling timer triggers an analog-to-digital converter to sample in the action interval of two zero vectors. The actual sampling time is determined according to a sampling time stamp, an analog-to-digital converter conversion delay, a current sensor response delay and an inverter dead time duration, and the branch current sampling value is compensated for time alignment based on the effective voltage vector and the corrected action duration of the dead time between the actual sampling time and the target alignment time, so as to reconstruct three-phase currents. According to the three-phase reconstructed currents of adjacent PWM periods and the injection polarity identifier, a high-frequency response current is extracted, the rotor position and speed are updated, and the voltage command of the next PWM period is generated. The application improves the low-speed position sensorless control precision.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, and in particular to a current injection sampling method based on multi-timer cooperation. Background Technology

[0002] Permanent magnet synchronous motor drive systems typically employ two or three current sensors to acquire the motor phase currents and use encoders, resolvers, or magnetic encoders to obtain the rotor position. Multiple current and position sensors increase the hardware cost, size, wiring complexity, and probability of failure of the drive. To reduce system cost, existing technologies use a single current sensor to acquire the inverter branch current and reconstruct the three-phase current based on the current relationships under different inverter switching states. Simultaneously, by injecting a high-frequency voltage into the permanent magnet synchronous motor, the high-frequency current response generated by the motor's salient pole effect is used to estimate the rotor position.

[0003] Existing single-current sensor current reconstruction methods typically perform two samplings within different voltage vector action intervals within a single PWM cycle. Since these two samplings occur at different physical moments, reconstructing the three-phase current using these sampled values ​​directly combines the current quantities at different time points, resulting in a sampling delay error. This error increases with the rate of change of current under high-frequency injected voltage, causing deviations in the amplitude and phase of the high-frequency response current, and further reducing the accuracy of rotor position estimation.

[0004] Some existing technologies reduce reconstruction errors by changing the PWM pulse position, inserting a compensating voltage vector, re-dividing the voltage sector, or fixing the time interval between two sampling points. These methods alter the order or duration of voltage vector action within the PWM cycle, causing distortion of the high-frequency injected voltage waveform and potentially introducing additional current harmonics. Other methods predict the current variation between sampling points based on the motor model, but these typically use theoretical sampling times for calculation, failing to adequately consider variations in the actual voltage vector action duration caused by PWM timer trigger deviations, ADC conversion delays, current sensor response delays, and inverter dead zones.

[0005] Furthermore, when the PWM timer, high-frequency injection control logic, and ADC sampling trigger are executed by software interrupts, interrupt response delays, task preemption, and peripheral trigger propagation delays can cause the actual sampling time to deviate from the theoretical sampling time. Existing technologies lack a unified approach that correlates the PWM time base, high-frequency injection time base, ADC sampling time base, and the inverter's actual vector action time base, and performs closed-loop compensation of the sampling current based on the actual sampling time. Summary of the Invention

[0006] To overcome the shortcomings of the above-mentioned background technology, such as inconsistent sampling times, inaccurate determination of actual sampling time, voltage vector action duration deviation caused by dead zone, and high-frequency injection response current distortion, this invention provides a current injection sampling method based on multi-timer cooperation.

[0007] This invention employs the following technical solution: a current injection sampling method based on multi-timer cooperation, applied to a motor controller. The motor controller is connected to a three-phase inverter, a single current sensor, and an analog-to-digital converter. The motor controller includes a PWM timer, an injection timer, and a sampling timer that are synchronized with each other. The method includes: generating a base voltage command based on the current rotor electrical angle, rotor electrical angular velocity, and current command; determining the duration of each voltage vector within the current PWM cycle based on the base voltage command using the PWM timer, and outputting a PWM synchronization event; generating a polarity identifier for a high-frequency injected voltage in response to the PWM synchronization event using the injection timer, and superimposing the high-frequency injected voltage corresponding to the polarity identifier onto the base voltage command to obtain an inverter voltage command; and generating, in response to the PWM synchronization event, a sampling timer in the two zero-vector action intervals of the current PWM cycle. First sampling trigger event and second sampling trigger event; acquire the first branch current sample value, the second branch current sample value, and the corresponding timestamp output by the analog-to-digital converter in response to the first sampling trigger event and the second sampling trigger event; determine the actual sampling time corresponding to the two branch current sample values ​​based on the timestamp, the analog-to-digital converter conversion delay, the single current sensor response delay, and the inverter dead time; perform time alignment compensation on the two branch current sample values ​​based on the effective voltage vector between each actual sampling time and the target alignment time and its duration after dead time correction, to obtain the three-phase reconstructed current at the target alignment time; extract the high-frequency response current based on the three-phase reconstructed current of adjacent PWM cycles and the polarity identifier, update the rotor electrical angle and the rotor electrical angular velocity based on the high-frequency response current, and generate the base voltage command for the next PWM cycle based on the updated rotor electrical angle and rotor electrical angular velocity.

[0008] Preferably, the PWM timer, the injection timer, and the sampling timer are synchronized by a hardware trigger signal; the PWM timer acts as the master timer and outputs the PWM synchronization event at the beginning of each PWM cycle; the injection timer and the sampling timer act as slave timers and reset or load the count value according to the PWM synchronization event.

[0009] Preferably, each voltage vector in the current PWM cycle includes a first zero vector, a first active vector, a second active vector, and a second zero vector; the first sampling trigger event is set at the center of the effective range of the first zero vector, and the second sampling trigger event is set at the center of the effective range of the second zero vector.

[0010] Preferably, the target alignment time is the center time of the effective range of the second zero vector; the effective range is the sampleable range after deducting the inverter dead zone, power switch switching delay, single current sensor setup time, and analog-to-digital converter sampling and holding time.

[0011] Preferably, determining the actual sampling time corresponding to the two branch current sample values ​​based on the timestamp, analog-to-digital converter conversion delay, single current sensor response delay, and inverter dead time includes: determining the trigger deviation of the corresponding sampling trigger event based on the theoretical count value when the sampling timer generates the sampling trigger event and the timestamp; and adding the trigger deviation, the analog-to-digital converter conversion delay, the single current sensor response delay, and the dead time equivalent delay to obtain the actual sampling time of the corresponding branch current sample value relative to the start time of the PWM cycle.

[0012] Preferably, the dead zone equivalent delay is determined based on the bridge arm where the switching state is switched and the direction of the phase current corresponding to the bridge arm; when the phase current direction shortens the actual duration of the corresponding voltage vector, the dead zone equivalent delay is set to a negative value; when the phase current direction extends the actual duration of the corresponding voltage vector, the dead zone equivalent delay is set to a positive value.

[0013] Preferably, the step of performing time alignment compensation on the sampled values ​​of the two branch currents based on the effective voltage vector between each actual sampling time and the target alignment time and its duration after dead-zone correction includes: calculating the rate of change of current in the stationary two-phase coordinate system based on the current three-phase reconfiguration current, stator resistance, d-axis inductance, q-axis inductance, rotor electric angular velocity, and the current effective voltage vector; multiplying the rate of change of current corresponding to each effective voltage vector by the duration after dead-zone correction according to the order of action of the effective voltage vectors to obtain the amount of change of current corresponding to each effective voltage vector; accumulating the amount of change of current corresponding to each effective voltage vector to obtain the amount of current compensation from the actual sampling time to the target alignment time; and superimposing the amount of current compensation onto the corresponding branch current sampled value to obtain the branch current value after time alignment compensation.

[0014] Preferably, the duration of action after dead-zone correction satisfies the following: ;in, The effective voltage vector duration after dead-time correction. The effective voltage vector duration obtained from modulation calculations. This refers to the inverter dead time. The correction factor is a value of -1, 0, or 1, and is determined by the bridge arm whose state changes during the effective voltage vector switching and the corresponding phase current direction.

[0015] Preferably, the single current sensor is used to collect the B-phase winding branch current in the first zero-vector action interval, and to collect the sum of the A-phase lower arm branch current and the B-phase winding branch current in the second zero-vector action interval; the three-phase reconfiguration current satisfies: ; ; ;in, The current value is the sampled value of the first branch current after time alignment compensation. This is the current value after time alignment compensation of the sampled current value of the second branch. , and These are the reconfiguration currents for phases A, B, and C, respectively.

[0016] Preferably, the step of extracting the high-frequency response current based on the three-phase reconstructed current of adjacent PWM cycles and the polarity identifier includes: converting the three-phase reconstructed current of the current PWM cycle into a stationary two-phase coordinate system current; calculating the current difference between the stationary two-phase coordinate system current of the current PWM cycle and the stationary two-phase coordinate system current of the previous PWM cycle; performing sign correction on the current difference according to the polarity identifier to obtain the high-frequency response current; transforming the high-frequency response current to an estimated rotating coordinate system to obtain the q-axis high-frequency response current; and inputting the q-axis high-frequency response current as a rotor position error signal into the position observer.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects:

[0018] Compared to existing technologies that reconstruct current solely based on theoretical sampling times, this invention uses multi-timer hardware synchronization to determine the PWM cycle boundary, injection polarity update time, and ADC sampling trigger time. It uses hardware timestamps to determine the actual occurrence deviation of sampling events and further incorporates ADC conversion delay, sensor response delay, and dead-time equivalent delay into the actual sampling time calculation. Furthermore, this invention calculates current changes based on the effective voltage vector sequence between actual sampling times, using the dead-time-corrected vector duration. It converts branch currents from two different physical times to the same target alignment time before reconstructing the three-phase current, reducing amplitude and phase errors of the high-frequency injected current. Attached Figure Description

[0019] Figure 1 This is the overall diagram of the application of low-speed sensorless start-up control for a centrifugal water pump permanent magnet synchronous motor in this invention. Detailed Implementation

[0020] The technical solution of the present invention will be fully described below with reference to the system structure and control flow shown in the accompanying drawings. It should be noted that the timer frequency, motor parameters, voltage, current, and calculation results in this embodiment are used to illustrate the data flow relationship and executability between the various technical steps, and are not intended to unduly limit the scope of protection of the claims.

[0021] This embodiment applies to a permanent magnet synchronous motor drive system. The permanent magnet synchronous motor drive system includes a motor controller, a DC power supply, a DC bus, a three-phase inverter, a single current sensor, and a permanent magnet synchronous motor. The three-phase inverter includes an A-phase bridge arm, a B-phase bridge arm, and a C-phase bridge arm. Each phase bridge arm includes an upper bridge arm power switch and a lower bridge arm power switch connected in series between the positive and negative terminals of the DC bus. The midpoints of the A-phase, B-phase, and C-phase bridge arms are respectively connected to the A-phase, B-phase, and C-phase windings of the permanent magnet synchronous motor. Each power switch is connected in reverse parallel with a freewheeling diode. The motor controller includes a processor, a memory, a PWM timer, an injection timer, a sampling timer, an analog-to-digital converter, a direct memory access controller, and a gate drive interface. The processor is connected to the memory, the three timers, the analog-to-digital converter, and the direct memory access controller. The input terminal of the gate drive interface is connected to the PWM output channel of the PWM timer, and the output terminal is connected to the gates of the six power switches of the three-phase inverter. The single current sensor is a feedthrough isolated Hall current sensor. The B-phase winding branch conductor and the A-phase lower bridge arm branch conductor pass through the core window of the single current sensor in the same magnetic flux detection direction. The analog output of the single current sensor is connected to the analog input of the analog-to-digital converter in sequence through a differential amplifier circuit and an anti-aliasing low-pass filter circuit.

[0022] First zero vector During operation, the upper bridge arm power switches of phases A, B, and C are turned on. The effective current passing through the core window is the phase B winding current, and the single current sensor output corresponds to: ; in the second zero vector During operation, the lower arm power switches of phases A, B, and C are turned on. The effective current passing through the core window is the sum of the lower arm current of phase A and the winding current of phase B. The output of the single current sensor corresponds to: In the formula, This is the sampled value of the first branch current. This is the sampled value of the second branch current. and These are the currents of phase A winding and phase B winding, respectively.

[0023] The PWM timer acts as the master timer, with its synchronization event output connected to the hardware synchronization inputs of both the injection timer and the sampling timer. The PWM timer outputs a PWM synchronization event each time it reaches the boundary of a PWM cycle. Upon receiving the PWM synchronization event, the injection timer loads the injection cycle count value. Upon receiving the PWM synchronization event, the sampling timer resets its counter and loads the first and second sample comparison values. The first and second comparison event outputs of the sampling timer are connected to the hardware trigger input of the analog-to-digital converter (ADC). The ADC's conversion completion event output is connected to the direct memory access controller (DMC). The DMC writes the current sample value, the timestamp captured by the sampling timer, and the polarity identifier output by the injection timer into the sampled data buffer in memory. This forms a hardware signal chain of "PWM synchronization event generation, injection polarity update, sampling trigger, current conversion, timestamp latching, and data transmission."

[0024] I. Known technologies used in this implementation method

[0025] 1. Space Vector Pulse Width Modulation

[0026] Conceptual Definition: Space Vector Pulse Width Modulation (SVM) is a well-known modulation method in the field of three-phase inverter control. It applies a zero vector and adjacent active vectors sequentially within a PWM cycle, making the time average of each vector equal to the target voltage vector. Physical Motivation: A three-phase two-level inverter can only generate eight switching states, while the motor current closed-loop output is a continuously changing voltage command. Therefore, it is necessary to synthesize a continuous voltage by utilizing the duration of different switching states.

[0027] Physical Motivation: A three-phase two-level inverter can only generate eight switching states, while the motor current closed-loop output is a continuously changing voltage command. Therefore, it is necessary to synthesize a continuous voltage by utilizing the duration of different switching states. Specific Execution Steps and Mathematical Expression: The processor adds the base voltage command and the high-frequency injected voltage to obtain the inverter voltage command in the stationary two-phase coordinate system. When the voltage command is located in the first region, the first active power vector is... The second active vector is Its duration of action satisfies: ; ; Symbol and parameter explanations: The PWM period; This is the DC bus voltage; The amplitude of the inverter voltage command; The angle between the inverter voltage command and the starting boundary of the current region; and These represent the total duration of action of two adjacent active vectors; This represents the total duration of action of the two zero vectors. Visualization: When , , , hour: ; ; The processor then generates a seven-segment PWM sequence containing two zero vectors and two active vectors.

[0028] 2. High-frequency square wave voltage injection

[0029] Conceptual Definition: High-frequency square wave voltage injection is a well-known method in the field of low-speed sensorless control of permanent magnet synchronous motors (PMSMs). It applies alternating positive and negative high-frequency voltages to the estimated d-axis of the estimated rotating coordinate system and estimates the rotor position based on the salient pole position information in the high-frequency response current. Physical Motivation: When a PMSM operates at zero and low speeds, the back electromotive force amplitude is insufficient to support stable position observation; the d-axis inductance and q-axis inductance of an embedded PMSM are not equal, and the high-frequency response current changes depending on the rotor direction.

[0030] Specific execution steps and mathematical expression: Injection timer outputs injection polarity indicator. Processor-generated: ; ; Symbol and parameter explanations: This refers to the PWM cycle number; and The first Estimated d-axis injection voltage and estimated q-axis injection voltage for each PWM cycle; This refers to the injection voltage amplitude. To inject polarity identifiers; This represents the number of PWM cycles contained in one high-frequency injection cycle. For example, when the PWM frequency is 20kHz and the high-frequency injection frequency is 5kHz... In four consecutive PWM cycles, the injection polarity indicators are 1, 1, −1, −1, respectively. When the injection amplitude is 4V, the corresponding estimated d-axis injection voltages are as follows: , , , .

[0031] 3. Hardware synchronization of multiple timers

[0032] Conceptual Definition: Multi-timer hardware synchronization is a well-known timing control technique in embedded control. It utilizes the trigger input, synchronization output, counter reset, and comparison matching functions between timers to allow multiple control events to share the same time base. Physical Motivation: Updating PWM, injection voltage, and ADC trigger times sequentially via software interrupts is affected by interrupt response delays and task preemption. With hardware synchronization, the time relationship between events is determined by the timer clock and the compare register. Specific Execution Steps and Mathematical Expression: The PWM timer outputs a synchronization event at the cycle boundary; the injection timer and sampling timer update their counting states in response to this synchronization event. The count value and physical time satisfy the following: Symbol and parameter explanations: This is the physical time relative to the start of the PWM cycle; This is the timer count value; This is used to count the clock frequency for the timer. A more concrete example: When... At that time, one count corresponds to 5ns. When the comparison value of the sampling timer is 3000, the sampling trigger event occurs relative to the start of the PWM cycle at: .

[0033] 4. Hardware timestamp

[0034] Conceptual Definition: Hardware timestamps are a well-known time measurement method in the field of digital control. They latch a timer count when a hardware event occurs, representing the event's occurrence time relative to a unified time base. Physical Motivation: The theoretical value written to the compare register only represents the target trigger time; trigger routing and peripheral synchronization introduce finite propagation delays. Latching the count value corresponding to the actual event quantifies this delay. Specific Execution Steps and Mathematical Expression: Let the theoretical count value of the sampled trigger event be... The timestamp of the latch is , No. The triggering deviation of each sampled triggering event is: Symbol and parameter explanations: Choose 1 or 2; For the first The theoretical count value of each sampled trigger event; For the corresponding timestamp; This refers to the trigger deviation. A concrete example: with a theoretical count of 3000, a latch timestamp of 3016, and a timer frequency of 200MHz, the trigger deviation is: .

[0035] 5. Inverter dead zone correction

[0036] Conceptual Definition: Inverter dead-time correction is a well-known compensation technique in the field of power electronics control. Dead time is the common turn-off time set when the upper and lower power switches of the same bridge arm switch over. The actual output voltage during the dead time is determined by the phase current direction and the conduction state of the freewheeling diode. Physical Motivation: The rate of change of current depends on the actual voltage vector applied to the motor terminals. If the theoretical vector duration calculated by modulation is used directly, the current compensation will include dead-time error. Specific Implementation Steps and Mathematical Expression: The processor identifies the bridge arm whose switching state changes during vector switching and determines the input based on the direction of the corresponding phase current. When the actual operating time is shortened... When the actual duration of action remains unchanged, When the actual duration of action is extended, Symbols and Parameters Explanation The duration of the vector action obtained from modulation calculation; The duration of effect after dead zone correction; Dead zone duration; This is the dead zone correction coefficient. Concrete explanation: When the theoretical vector's duration is 6... Dead zone duration is 1 When the direction of the phase current causes a shortening of the actual duration of action: .

[0037] 6. Clarke transform and Park transform

[0038] Conceptual Definition: Both Clarke transform and Park transform are well-known coordinate transformations in the field of AC motor control. The Clarke transform converts three-phase stationary coordinate system currents into two-phase stationary coordinate system currents; the Park transform converts two-phase stationary coordinate system currents into two-phase coordinate system currents that rotate with the estimated rotor position. Physical Motivation: The three-phase currents satisfy... It has only two independent components. Coordinate transformation can convert three-phase AC quantities into two-phase quantities suitable for closed-loop regulation and position observation.

[0039] Specific execution steps and mathematical expression: ; Symbol and parameter explanations: , , It is a three-phase current; , The current is in a stationary two-phase coordinate system. , To estimate the current in the rotating coordinate system; To estimate the rotor electrical angle. Visualization: When , , hour: ; .

[0040] 7. Calculation of the rate of change of current in the motor model

[0041] Conceptual Definition: Calculating the rate of change of current based on the voltage equation is a well-known model prediction method in the field of motor control. It calculates the change in current per unit time based on winding resistance, inductance, speed, current, and applied voltage. Physical Motivation: The sampled current values ​​of two branches correspond to different physical moments and cannot be directly combined. It is necessary to calculate the change in current between the sampling moment and the target alignment moment, converting the two sampled values ​​to the same moment.

[0042] Specific execution steps and mathematical expression: A simplified model using a stationary two-phase coordinate system is adopted under low-speed, high-frequency injection conditions. . No. The current change corresponding to each vector segment is: The total current compensation is: Symbol and parameter explanations: Stator resistance; and These are the d-axis inductance and the q-axis inductance, respectively. The rotor's electric angular velocity; , The static two-phase voltage corresponding to the current vector; For the first Rate of change of current within each vector segment; This refers to the duration of action of the corresponding vector segment after dead zone correction; This represents the number of vector segments between the actual sampling time and the target alignment time. A more concrete explanation: when the rate of change of the B-phase current within a vector segment is... The corrected duration is At that time, the change in phase B current generated by this vector segment is: .

[0043] 8. Proportional-integral position observer

[0044] Conceptual Definition: The proportional-integral (PI) position observer is a well-known closed-loop observation structure in the field of sensorless control. It adjusts the estimated electrical angular velocity based on the position error signal and integrates the estimated electrical angular velocity to obtain the estimated electrical angle. Physical Motivation: The high-frequency response current carries rotor position error information, but it contains sampling noise and switching ripple. The closed-loop observer can suppress high-frequency disturbances and continuously output rotor position and velocity. Specific Execution Steps and Mathematical Expression: ; ; Symbol and parameter explanations: For the first Position error signal for one PWM cycle; For estimation Shaft high-frequency response current; This is the proportionality coefficient; The integral coefficient; To estimate the rotor's electrical angular velocity; To estimate the rotor electrical angle. Visualization: When , , , Integration status is hour: .exist Under these conditions, the electrical angle increment for this cycle is:

[0045] II. Control Flow Based on Multi-Timer Collaboration

[0046] Step S101: Generate base voltage command

[0047] The processor reads the target aligned three-phase reconfiguration current obtained in the previous PWM cycle and performs Clarke and Park transformations to obtain the estimated d-axis feedback current in the rotating coordinate system. and q-axis feedback current The processor calculates the d-axis current error and the q-axis current error separately: ; In the formula, and These are the d-axis current command and the q-axis current command, respectively. and These represent the d-axis current error and the q-axis current error, respectively. The d-axis and q-axis current regulators output base voltage commands: ; In the formula, and These are the scaling factors for the d-axis and q-axis, respectively; and These are the integral coefficients for the d-axis and q-axis, respectively; It is a permanent magnet flux linkage.

[0048] Step S102: Generate injection voltage and PWM timing

[0049] The injection timer updates the injection polarity flag based on PWM synchronization events. The processor then adds the high-frequency injection voltage to the base voltage instruction. ; The processor performs an inverse Park transformation based on the estimated rotor electrical angle to obtain the inverter voltage command in the stationary two-phase coordinate system. The PWM timer determines the voltage vector region, the duration of the first active vector, the duration of the second active vector, and the duration of the zero vector based on the inverter voltage command, and loads the corresponding comparison values ​​into the PWM compare register.

[0050] Step S103: Determine the sampling trigger time

[0051] The processor calculates the first target sampling time and the second target sampling time based on the start times and effective ranges of the first and second zero vectors: ; In the formula, and These are the starting times of the first zero vector and the second zero vector, respectively. and These are the effective durations after deducting dead time, power switch switching delay, sensor setup time, and analog-to-digital converter sampling and holding time. The processor will... and Convert to sampling timer count value: ; The sampling timer reaches the count value. and The first sampling trigger event and the second sampling trigger event are generated respectively.

[0052] Step S104: Obtain sampled values ​​and actual sampling time

[0053] The analog-to-digital converter (ADC) completes two current conversions in response to two sampling trigger events. The direct memory access controller writes the first branch current sample value, the second branch current sample value, the first timestamp, and the second timestamp into the sampling data buffer. The actual sampling time for each current sample value is: In the formula, No. Each actual sampling time; The corresponding target trigger time; This is the conversion delay of the analog-to-digital converter; For single current sensor response delay; This is the equivalent delay of the dead zone, determined based on the direction of the bridge arm and phase current.

[0054] Step S105: Perform time alignment compensation

[0055] The processor sets the center time of the effective range of the second zero vector as the target alignment time. And calculate them separately: ; The processor queries the vector sequence table stored in the PWM timer to determine the effective voltage vectors that pass sequentially between each actual sampling time and the target alignment time, and calculates the duration of each vector after dead-time correction. For the first branch current sampling value, the processor executes the process segment by segment according to the vector action sequence: The current obtained at the end of each vector segment is used as the input for calculating the rate of change of current in the next vector segment. Finally, the first compensation current value at the target alignment moment is obtained. The second branch current sampling value is processed in the same way to obtain the second compensation current value. .

[0056] Step S106: Reconstruct the three-phase current processor

[0057] Calculated based on the two time-aligned branch current values: ; ; .therefore: The first and second compensation current values ​​both correspond to the target alignment time, and there is no situation where the current values ​​at different times are directly added or subtracted during the reconstruction process.

[0058] Step S107: Extract the high-frequency response and update the rotor state

[0059] The processor converts the three-phase reconstructed current of the current PWM cycle into a stationary two-phase coordinate system current. And calculate: Perform sign correction based on the injected polarity identifier: The sign-corrected high-frequency response current is transformed to the estimated rotating coordinate system: The processor will As the position error signal input to the proportional-integral (PI) position observer, the updated estimated rotor electrical angular velocity and estimated rotor electrical angle are obtained. The updated result is fed back to step S101 to generate the base voltage command for the next PWM cycle, thus forming a control closed loop of "current acquisition, time calibration, time alignment, three-phase reconstruction, high-frequency response extraction, rotor state update, and voltage command generation".

[0060] Application Scenario Example: Low-speed sensorless start-up control of permanent magnet synchronous motor in centrifugal water pump

[0061] like Figure 1 As shown, this embodiment applies the current injection sampling method based on multi-timer cooperation to a centrifugal water pump driver. The water pump uses an embedded permanent magnet synchronous motor. During the stationary start-up and low-speed operation phases, the rotor position cannot be stably estimated using back electromotive force. Therefore, a high-frequency square wave voltage injection method is used to obtain rotor position information. The driver is equipped with only one through-hole Hall current sensor. By collecting the combined currents of different branches in two zero-vector action intervals within the same PWM cycle, the two sampled values ​​are compensated to the same target alignment time to reconstruct the three-phase winding current.

[0062] In this embodiment, the control process is executed unilaterally by the motor controller. The three-phase inverter, single current sensor, and permanent magnet synchronous motor serve as the controlled objects or data sources, and the motor controller does not use the processing actions of other devices as method steps.

[0063] The values ​​in this embodiment are used to fully illustrate the entire process within one PWM cycle, from voltage command generation, timer coordination, branch current acquisition, time alignment, three-phase current reconstruction, high-frequency response extraction to voltage command update for the next PWM cycle. All parameters are defined values; undefined range parameters are not used.

[0064] Pump Motor: In this embodiment, a 750W embedded permanent magnet synchronous motor is used to drive the centrifugal pump impeller. The A-phase, B-phase, and C-phase windings of the motor are connected in a star configuration, and the neutral point is not brought out. Therefore, the three-phase winding currents satisfy the following: .

[0065] The motor parameters are shown in Table 1 below.

[0066] Table 1 Motor Parameters

[0067] The rotor's electric angular velocity is determined by the following formula: Substituting the parameters into this embodiment, we get: .

[0068] 2. Three-phase inverter

[0069] The three-phase inverter is a three-phase two-level voltage-type inverter, comprising phase A, phase B, and phase C arms. Each phase arm includes one upper arm power switch and one lower arm power switch, with freewheeling diodes connected in reverse parallel to each power switch. The DC input terminal of the three-phase inverter is connected to the 48V DC bus; the midpoints of phase A, phase B, and phase C arms are connected to the A-phase, B-phase, and C-phase windings of the motor, respectively. The fixed parameters of the inverter are shown in Table 2 below.

[0070] Table 2 Parameter Configuration Table

[0071] Power switching transistor type N-channel MOSFET DC bus voltage 48V PWM frequency 20kHz PWM cycle 50μs Dead Zone Duration 1.00μs MOSFET turn-on delay 0.18μs MOSFET turn-off delay 0.25μs Gate drive propagation delay 0.12μs

[0072] 3. Single current sensor

[0073] The single current sensor employs an isolated through-hole Hall current sensor. The B-phase winding branch conductor and the A-phase lower bridge arm branch conductor pass through the core window of the Hall current sensor in the same magnetic flux detection direction. The analog output of the Hall current sensor is connected to the analog-to-digital converter input of the motor controller via a second-order low-pass filter circuit. The sensor and analog front-end parameters are shown in Table 3 below.

[0074] Table 3 Parameter Specifications

[0075] Measurement range (-20A) to (20A) Zero current output voltage 1.650V Current sensitivity 0.100V / A Sensor response delay 0.250μs Low-pass filter cutoff frequency 100kHz Simulated front-end gain 1 Analog front-end input bias 0V

[0076] First zero vector During operation, the single current sensor output corresponds to the current in phase B winding: In the second zero vector During operation, the single current sensor output corresponds to the sum of the current in phase A winding and the current in phase B winding: .

[0077] 4. Motor controller

[0078] The motor controller includes a processor, memory, PWM timer, injection timer, sampling timer, 16-bit analog-to-digital converter (ADC), direct memory access controller (DMI), and inverter drive interface. The connections between these components are as follows: the six complementary PWM outputs of the PWM timer are connected to the six power switches of the three-phase inverter via the gate drive interface; the synchronization event outputs of the PWM timer are connected to the hardware synchronization inputs of the injection timer and sampling timer; the first and second comparison event outputs of the sampling timer are connected to the hardware trigger input of the ADC; the analog input of the ADC is connected to the analog output of a single current sensor; the conversion completion event output of the ADC is connected to the DMI; the DMI is connected to the capture register of the sampling timer, the ADC data register, and the sampling data buffer in the memory; the processor reads the branch current sampling values, timestamps, and injection polarity identifiers from the sampling data buffer, and performs time alignment compensation, three-phase current reconstruction, and rotor position estimation.

[0079] The controller parameters are shown in Table 4 below.

[0080] Table 4 Parameter Configuration Table

[0081] processor clock speed 200MHz Timer clock frequency 200MHz A single timer count corresponds to a certain time. 5ns PWM timer counting mode Center-aligned count PWM timer half-cycle count value 5000 Sampling timer period count value 10000 Analog-to-digital converter resolution 16bit Analog-to-digital converter reference voltage 3.300V Analog-to-digital converter conversion delay 0.550μs Analog-to-digital converter sample-and-hold time 0.200μs DMA sampled data length 6 32-bit data Current control cycle 50μs Location observation period 50μs

[0082] The PWM timer uses center-aligned counting. The timer increments from 0 to 5000, then decrements from 5000 back to 0. One complete counting cycle is: .

[0083] I. Control Software Data Structure

[0084] The processor maintains the following data in each PWM cycle.

[0085] 1. Base voltage command: Its matrix dimension is .

[0086] 2. High-frequency injection voltage: Its matrix dimension is .

[0087] 3. Inverter voltage command: Its matrix dimension is .

[0088] 4. Three-phase reconfiguration current: Its matrix dimension is .

[0089] 5. Static two-phase reconfiguration current: Its matrix dimension is .

[0090] 6. Each DMA transfer data frame includes, in sequence: .in, and These are the first and second timestamps, respectively. and These are the results of two analog-to-digital conversions; To inject polarity identifiers; For PWM cycle

[0091] Period number.

[0092] II. High-frequency injection and timer coordination parameters

[0093] This embodiment uses estimated d-axis high-frequency square wave voltage injection, as shown in Table 5.

[0094] Table 5 High-Frequency Injection Parameter Configuration Table

[0095] High frequency injection voltage amplitude 4.000V High frequency injection frequency 5kHz Number of PWM cycles contained in each injection cycle 4 Injection polar sequence +1,+1,-1,-1 Current PWM cycle number k=0 Current Injection Polarity Identifier σ(0)=1

[0096] The injection timer responds to the PWM synchronization event and counts the PWM cycles. The current PWM cycle is the first PWM cycle within the injection cycle, therefore... ; .

[0097] The PWM timer outputs a hardware synchronization event at the beginning of each PWM cycle. Both the injection timer and the sampling timer respond to this hardware synchronization event by resetting or loading their counters, without starting the counting via a processor interrupt.

[0098] III. Execution steps of a complete PWM cycle

[0099] Step S201: Read the state quantity from the previous cycle

[0100] At the start of the current cycle, the processor reads the state data obtained from the previous PWM cycle: ; The estimated current in the rotating coordinate system for the previous cycle was: ; The current command for this period is: ; Therefore, the d-axis and q-axis current errors are: ; .

[0101] Step S202: Generate base voltage command

[0102] The d-axis and q-axis current regulators use proportional-integral (PI) regulators with the following parameters: d-axis proportional coefficient. 4.000V / A; q-axis scaling factor 4.000V / A; d-axis integral coefficient 800V / (A·s); q-axis integral coefficient : 800V / (A·s); d-axis integral state: 0.005832A·s; q-axis integral state: 0.001710A·s.

[0103] In this embodiment, the base voltage command is calculated using the following formula for the current cycle: ; Substituting the specific values, we get: ; ; ; The base voltage command is: .

[0104] Step S203: Superimpose high-frequency injection voltage. The current injection polarity identifier is 1, and the injection amplitude is 4V. Therefore: ; ; The estimated voltage command for the superimposed rotating coordinate system is: The processor performs an inverse Park transform based on the currently estimated rotor electrical angle of 0.200000 rad: ; .

[0105] in: ; .so: ; ; ; The voltage command amplitude is: The voltage command phase angle is: The voltage command is located in the first sector of the space vector.

[0106] Step S204: Calculate the duration of voltage vector action. Active vector is used in the first sector. and The total duration of action of the two active vectors is calculated according to the following formula: ; Substitute parameters: ; ; ; The total duration of action of the zero vector is: .

[0107] The following symmetrical voltage vector sequences are used in this period, as shown in Table 6.

[0108] Table 6 Symmetrical Voltage Vector Sequence

[0109] 0~6μs (V7) 111 6μs 6~10μs (V2) 110 4μs 10–15 μs (V1) 100 5μs 15~35μs (V0) 000 20μs 35~40μs (V1) 100 5μs 40~44μs (V2) 110 4μs 44~50μs (V7) 111 6μs

[0110] The sum of the durations of each vector is: .

[0111] Step S205: Configure the first sampling trigger table event and the second sampling trigger table event.

[0112] The first sampling trigger table event is located in the first Therefore, the center of the effective interval is: Its sampling timer comparison value is: The second sampling trigger table event is located in Therefore, the center of the effective interval is: Its sampling timer comparison value is: In this embodiment, the target alignment time is set within the effective range of the second zero vector and after the second target sampling time. Location: The alignment time of this target is between 15 and 35 μs. Within the operating range, the time distance from the switching edge of any power switch is greater than 9μs.

[0113] Step S206: Perform hardware-triggered sampling twice.

[0114] The PWM timer outputs a PWM synchronization event at the start of the current cycle. The sampling timer responds to this PWM synchronization event by resetting its count to zero. When the sampling timer count reaches 600, a first sampling trigger event is generated, and the analog-to-digital converter (ADC) acquires the B-phase winding branch current output from the single current sensor. When the sampling timer count reaches 5000, a second sampling trigger event is generated, and the ADC acquires the sum of the A-phase winding current and the B-phase winding current output from the single current sensor.

[0115] The timestamps captured by the hardware and the ADC conversion results are shown in Table 7.

[0116] Table 7 Conversion Results

[0117] Theoretical comparison value 600 5000 Capture timestamp 612 5008 Trigger deviation count 12 8 ADC raw value 35151 34833

[0118] The first trigger deviation is: The second trigger deviation is: .

[0119] Step S207: Convert the raw ADC value into the branch current sample value.

[0120] The ADC input voltage is calculated using the following formula: The first ADC input voltage is: The sampled value of the first branch current is: .

[0121] The processor is represented using an internal current quantization unit of 1mA as: The second ADC input voltage is: The sampled value of the second branch current is: .

[0122] Step S208: Calculate the actual sampling time of the current samples in the two branches.

[0123] The dead-time equivalent delay for the first sample is 0.140 μs. The dead-time equivalent delay for the second sample is -0.440 μs. Negative values ​​indicate that the current phase current direction causes the actual current state corresponding to this sample to be earlier than the current state without considering the dead time. The first actual sampling time is: ; ; The second actual sampling time is: ; ; The time deviation between the two actual sampling times and the target alignment time is: ; .

[0124] Step S209: Determine the effective vector sequence between the first actual sampling time and the target alignment time.

[0125] The first actual sampling time was The target alignment time is This interval spans the following vector segments: Remaining action segment; First functional segment; First functional segment; Pre-operation phase. Based on the dead time, the switching arm, and the corresponding phase current direction, the processor determines the corrected effective operating time as shown in Table 8.

[0126] Table 8 Effective Duration

[0127] <![CDATA[V7 remaining segment]]> 4~6μs 0 2.000μs <![CDATA[V2 section]]> 6~10μs -0.5 3.500μs <![CDATA[V1 section]]> 10–15 μs 0.5 5.500μs <![CDATA[V0 front section]]> 15~25.5μs 0 10.500μs

[0128] The effective duration of action is calculated according to the following formula: ;For example, The theoretical duration of action of the segment is The correction factor is Therefore: . The theoretical duration of action of the segment is The correction factor is Therefore: The sum of the durations of each segment after correction is: The result deviates from the first time. Consistent. The processor reads the initial value of the A-phase current obtained from the extrapolation of the model in the previous cycle: Because the Clarke transform satisfies: ; .therefore: Substitute parameters: ; The initial state of the stationary two-phase current at the first actual sampling moment is as follows: .

[0129] Step S211: Calculate the time alignment compensation amount of the first branch current segment by segment.

[0130] This embodiment employs the following current change rate model under low-speed, high-frequency injection conditions: In this embodiment: ; The voltages of each basic voltage vector in the stationary two-phase coordinate system are: ; ; ; .

[0131] calculate The remaining segment input current state is as follows: ; Substituting into the current change rate model, we get: ; The corrected duration is... ,therefore: ; At the end of this paragraph: ; .

[0132] calculate Duan Yi As input, the voltage is ,get: ; The corrected duration is... ,therefore: ; At the end of this paragraph: ; .

[0133] calculate Duan Yi As input, the voltage is ,get: ; The corrected duration is... ,therefore: ; At the end of this paragraph: ; .

[0134] calculate The first section As input, the voltage is ,get: . The duration of action is ,therefore: ; The two-phase currents at the target alignment moment are: ; The two-phase currents at the target alignment moment are inversely transformed into B-phase current: ; ; Therefore, the time alignment compensation for the first branch current is: The first compensation current value is: .

[0135] Step S212: Calculate the time alignment compensation amount of the second branch current.

[0136] The second actual sampling time is The target alignment time is Both are located Within the effective period. The second time deviation is: Within this interval, the following calculations are made based on the current state near the target alignment time: ; The rate of change of phase B current is: ; ; The rate of change of the sum of the currents in phase A and phase B is: ; The compensation amount for the second branch current is: ; The second compensation current value is: The current calculation accuracy is based on the controller's 1mA current and is saved as follows: .

[0137] Step S213: Reconstruct the three-phase current at the target alignment moment

[0138] Based on the branch relationships of a single current sensor: ; ; The calculation was performed using the unquantified compensation results: ; ; The sum of the three-phase reconfiguration currents is: The three-phase reconstructed current matrix at the target alignment moment is: .

[0139] Step S214: Perform Clarke transform

[0140] according to: ; .get: ; ; .therefore: .

[0141] Step S215: Extract the high-frequency response current

[0142] The stationary two-phase current obtained at the corresponding target alignment time in the previous PWM cycle is: The current difference between the current cycle and the previous cycle is: ; The high-frequency response current is: ; The current injection polarity flag is 1, therefore the sign-corrected high-frequency response current is: ; .

[0143] Step S216: Calculate the rotor position error signal

[0144] Transform the high-frequency response current to the estimated rotating coordinate system: Substitute the parameters: ; The rotor position error signal for this period is: .

[0145] Step S217: Update rotor electric angular velocity and rotor electric angle

[0146] The position observer parameters are as follows: Scale factor K p 300, Integral coefficient K i 18000, Current Integral Status I θ (k): 0.002700 A·s, observation period: 50 μs. The estimated rotor electric angular velocity is: ; ; The updated points status is as follows: ; ; The updated rotor electrical angle is: ; ; .

[0147] Step S218: Generate the base voltage command for the next PWM cycle.

[0148] The d-axis current regulator integral status is updated as follows: ; The q-axis current regulator integral state is updated as follows: ; The base d-axis voltage command for the next PWM cycle is: ; The base q-axis voltage command for the next PWM cycle is: ; Since the next PWM cycle is still in the second positive polarity cycle of the injected polarity sequence, therefore: The estimated total d-axis voltage command for the next PWM cycle is: The estimated total voltage command for the q-axis is: The processor performs an inverse Park transform using the updated rotor electrical angle of 0.202517 rad, resulting in: ; . ; The voltage command is input into the space vector pulse width modulation calculation for the next PWM cycle, thus completing the data loop from sampling to control output update for this cycle.

[0149] IV. Timer Abnormalities and Sampling Validity Judgment

[0150] To prevent invalid sampled data from entering the current reconstruction and position observation stages, this embodiment performs the following deterministic judgment. The effective sampling windows for the first and second zero vectors respectively satisfy the following conditions: ; .in: ; ; The effective sampling window for the first zero vector is: The effective sampling window for the second zero vector is: This embodiment specifies the minimum effective sampling window as: .because and All greater than Both samples are valid. Timestamp deviation judgment: This embodiment specifies the maximum allowable hardware trigger deviation as follows: The first trigger deviation is The second trigger deviation is All are less than Therefore, the timestamp for this cycle is valid. Three-phase current consistency judgment: Processor calculation: In this embodiment: This embodiment specifies that the three-phase current consistency threshold is... .because: The three-phase reconfiguration current is valid for this period. Current compensation limit: This embodiment specifies that the absolute value of the branch current compensation for a single cycle must not exceed [a certain limit]. The absolute value of the current compensation for the first branch is: The absolute value of the current compensation for the second branch is: Both are smaller than Therefore, it allows the current input position observer and current regulator to be reconfigured in this cycle.

[0151] V. Continuous Operation Process

[0152] During the pump's static start-up phase, the processor repeatedly executes steps S201 to S218 according to a control cycle of 50 μs. The following parameters are used during the operation, as shown in Table 9.

[0153] Table 9 Parameters

[0154] Rotor initial positioning 0～0.20s 0r / min 1.0A low speed start 0.20～1.00s Increase from 0 to 300 r / min 3.0A Low-speed closed-loop operation 1.00～2.00s 300r / min 3.0A medium speed acceleration 2.00～3.00s Increase from 300 to 1200 r / min 4.0A High-frequency injection exit 3.00～3.20s 1200r / min 4.0A

[0155] The high-frequency injection voltage maintains a 4V amplitude when the mechanical speed is below 1000 r / min; after the mechanical speed reaches 1000 r / min, the processor reduces the injection voltage amplitude by 0.01V per PWM cycle; it takes 400 PWM cycles for the injection voltage amplitude to decrease from 4V to 0V, corresponding to the following time: After the high-frequency injection is completed, the processor switches to the back EMF position observation mode. During the switching process, the multiple timers maintain synchronization between the PWM timer and the sampling timer for phase current closed-loop sampling.

[0156] VI. Methods for Verifying the Deterministic Effects of Implementation

[0157] This embodiment uses a discrete motor model with a duration of 0.10s to verify the time alignment process. The simulation integration step size is fixed at 0.10μs, encompassing 2000 PWM cycles. The synchronous three-phase current is calculated from the motor state equations with a step size of 0.10μs and saved as the reference current at each target alignment moment.

[0158] The following three processing methods are adopted respectively: directly using the sampled values ​​of the two asynchronous branches for three-phase current reconstruction; performing current compensation according to the theoretical sampling time, but without using hardware timestamps and dead-time correction; and using the multi-timer synchronization, hardware timestamp, dead-time correction and segmented current time alignment method of this embodiment.

[0159] The verification results are shown in Table 10.

[0160] Table 10 Verification Results

[0161] B-phase current root mean square error 0.286A 0.132A 0.061A High-frequency response current amplitude error 18.4% 8.7% 3.1% High-frequency response current phase error 11.6° 5.2° 1.8° Root mean square error of rotor electrical angle 0.214 rad 0.126 rad 0.071 rad Standard deviation of actual sampling time error 0.420μs 0.420μs 0.035μs

[0162] Compared to the method of performing compensation only based on theoretical timing, the root mean square error of the B-phase current in this embodiment decreases by the following percentage: The percentage decrease in the root mean square error of the rotor electrical angle is: Therefore, this embodiment determines a unified time base for control events through hardware synchronization between the PWM timer, injection timer, and sampling timer; determines the actual sampling time of the branch current sample value through timestamps; determines the actual voltage vector action duration at the motor end through dead-zone correction; converts the two asynchronous branch currents to the same target alignment time through segmented current change rate calculation; and extracts the high-frequency response current, updates the rotor state, and generates the voltage command for the next PWM cycle based on the reconstructed three-phase current, forming a complete closed loop of sensing, time correction, state estimation, and inverter control.

[0163] The above description is merely a preferred embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present application, based on the technical solution and concept of the present application, should be covered within the scope of protection of the present application.

Claims

1. A current injection sampling method based on multi-timer cooperation, characterized in that, This method is applied to a motor controller connected to a three-phase inverter, a single current sensor, and an analog-to-digital converter. The motor controller includes a PWM timer, an injection timer, and a sampling timer that are synchronized with each other. The method includes: generating a base voltage command based on the current rotor electrical angle, rotor electrical angular velocity, and current command; determining the duration of each voltage vector within the current PWM cycle based on the base voltage command using the PWM timer and outputting a PWM synchronization event; generating a polarity identifier for a high-frequency injected voltage in response to the PWM synchronization event using the injection timer, and superimposing the high-frequency injected voltage corresponding to the polarity identifier onto the base voltage command to obtain the inverter voltage command; and generating a first sampling trigger event and a second sampling trigger event within the two zero-vector action intervals of the current PWM cycle, respectively, using the sampling timer in response to the PWM synchronization event. The process involves: acquiring the first branch current sample value, the second branch current sample value, and the corresponding timestamp output by the analog-to-digital converter in response to the first and second sampling trigger events; determining the actual sampling time corresponding to the two branch current sample values ​​based on the timestamp, the analog-to-digital converter conversion delay, the single current sensor response delay, and the inverter dead time; performing time alignment compensation on the two branch current sample values ​​based on the effective voltage vector between each actual sampling time and the target alignment time and its duration after dead time correction to obtain the three-phase reconstructed current at the target alignment time; extracting the high-frequency response current based on the three-phase reconstructed current of adjacent PWM cycles and the polarity identifier; updating the rotor electrical angle and the rotor electrical angular velocity based on the high-frequency response current; and generating the base voltage command for the next PWM cycle based on the updated rotor electrical angle and rotor electrical angular velocity.

2. The current injection sampling method based on multi-timer cooperation according to claim 1, characterized in that, The PWM timer, the injection timer, and the sampling timer are synchronized by a hardware trigger signal; the PWM timer acts as the master timer and outputs the PWM synchronization event at the beginning of each PWM cycle; the injection timer and the sampling timer act as slave timers and reset or load the count value according to the PWM synchronization event.

3. The current injection sampling method based on multi-timer cooperation according to claim 1, characterized in that, Each voltage vector in the current PWM cycle includes a first zero vector, a first active vector, a second active vector, and a second zero vector; the first sampling trigger event is set at the center of the effective range of the first zero vector, and the second sampling trigger event is set at the center of the effective range of the second zero vector.

4. The current injection sampling method based on multi-timer cooperation according to claim 3, characterized in that, The target alignment time is the center time of the effective range of the second zero vector; the effective range is the sampleable range after deducting the inverter dead zone, power switch switching delay, single current sensor setup time, and analog-to-digital converter sampling and holding time.

5. The current injection sampling method based on multi-timer cooperation according to claim 1, characterized in that, The step of determining the actual sampling time corresponding to the two branch current sample values ​​based on the timestamp, analog-to-digital converter conversion delay, single current sensor response delay, and inverter dead time includes: determining the trigger deviation of the corresponding sampling trigger event based on the theoretical count value when the sampling timer generates the sampling trigger event and the timestamp; and adding the trigger deviation, the analog-to-digital converter conversion delay, the single current sensor response delay, and the dead time equivalent delay to obtain the actual sampling time of the corresponding branch current sample value relative to the start time of the PWM cycle.

6. The current injection sampling method based on multi-timer cooperation according to claim 5, characterized in that, The dead zone equivalent delay is determined based on the bridge arm where the switching state changes and the direction of the phase current corresponding to the bridge arm; when the phase current direction shortens the actual duration of the corresponding voltage vector, the dead zone equivalent delay is set to a negative value; when the phase current direction extends the actual duration of the corresponding voltage vector, the dead zone equivalent delay is set to a positive value.

7. The current injection sampling method based on multi-timer cooperation according to claim 1, characterized in that, The time alignment compensation for the sampled current values ​​of the two branches, based on the effective voltage vector between each actual sampling time and the target alignment time and its duration after dead-zone correction, includes: calculating the rate of change of current in the stationary two-phase coordinate system according to the current three-phase reconfiguration current, stator resistance, d-axis inductance, q-axis inductance, rotor electric angular velocity, and the current effective voltage vector; multiplying the rate of change of current corresponding to each effective voltage vector by the duration after dead-zone correction according to the order of action of the effective voltage vectors to obtain the amount of change of current corresponding to each effective voltage vector; accumulating the amount of change of current corresponding to each effective voltage vector to obtain the amount of current compensation from the actual sampling time to the target alignment time; and superimposing the amount of current compensation onto the corresponding branch current sampled value to obtain the branch current value after time alignment compensation.

8. The current injection sampling method based on multi-timer cooperation according to claim 7, characterized in that, The duration of action after dead-zone correction satisfies: ;in, The effective voltage vector duration after dead-time correction. The effective voltage vector duration calculated by modulation. This refers to the inverter dead time. The correction factor is a value of -1, 0, or 1, and is determined by the bridge arm whose state changes during the effective voltage vector switching and the corresponding phase current direction.

9. The current injection sampling method based on multi-timer cooperation according to claim 1, characterized in that, The single current sensor is used to collect the B-phase winding branch current in the first zero vector action interval, and to collect the sum of the A-phase lower arm branch current and the B-phase winding branch current in the second zero vector action interval. The three-phase reconfiguration current satisfies: ; ; ;in, The current value is the sampled value of the first branch current after time alignment compensation. This is the current value after time alignment compensation of the sampled current value of the second branch. , and These are the reconfiguration currents for phases A, B, and C, respectively.

10. The current injection sampling method based on multi-timer cooperation according to claim 1, characterized in that, The step of extracting the high-frequency response current based on the three-phase reconstructed current of adjacent PWM cycles and the polarity identifier includes: converting the three-phase reconstructed current of the current PWM cycle into a stationary two-phase coordinate system current; calculating the current difference between the stationary two-phase coordinate system current of the current PWM cycle and the stationary two-phase coordinate system current of the previous PWM cycle; performing sign correction on the current difference according to the polarity identifier to obtain the high-frequency response current; transforming the high-frequency response current to the estimated rotating coordinate system to obtain the q-axis high-frequency response current; and inputting the q-axis high-frequency response current as a rotor position error signal into the position observer.

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