A method and device for standardizing control of a permanent magnet synchronous motor

Abstract

This invention provides a per-unit control method and apparatus for a permanent magnet synchronous motor, belonging to the field of motor control technology. The method includes: standardizing the phase current to obtain the per-unit phase current; standardizing the rotor position to obtain the per-unit rotor position; standardizing the rotor speed to obtain the per-unit rotor speed; and standardizing the motor parameters to obtain the per-unit motor parameters, including: flux linkage, and the inductance of the motor's d-axis and q-axis. The permanent magnet synchronous motor is controlled based on the per-unit phase current, rotor position, rotor speed, and motor parameters. This method can eliminate the influence of differences in size, voltage, and other parameters between different motors, simplifying the design and analysis process, and can be used for the control of different types of motors.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology, and in particular relates to a per-unit control method and device for a permanent magnet synchronous motor. Background Technology

[0002] With the development of multi-electric technology, future aircraft will have more diverse needs and requirements for drive motors in airborne equipment such as transfer pumps, booster pumps, EMA actuators, circulating fans, and compressors. Different systems require motors with different power ratings, speeds, and output torques, resulting in variations in motor parameters, dimensions, weight, voltage ratings, and current ratings. Motors with different parameters require different control methods, and the control parameters also differ, consuming significant time, manpower, material resources, and financial resources in motor testing and debugging. Summary of the Invention

[0003] This invention provides a per-unit control method and device for permanent magnet synchronous motors, applicable to the control of different types of motors. The technical solution is as follows: Firstly, a per-unit control method for a permanent magnet synchronous motor is provided, the method comprising: Step 1: Standardize the phase current by unit to obtain the standardized phase current; Step 2: Mark the rotor position by one unit to obtain the rotor position after marking by one unit; Step 3: Standardize the rotor speed per unit to obtain the rotor speed after standardization; Step 4: Standardize the motor parameters to obtain the standardized motor parameters, which include: flux linkage. Inductance of the motor's d-axis and q-axis , ; Step 5: Perform permanent magnet synchronous motor control based on the phase current, rotor position, rotor speed, and motor parameters after per-unit measurement.

[0004] Among them, the given rotational speed Feedback rotational speed from position and speed modules n The difference, after being processed by the PI controller, is used as the input to the current control module, and the output 1 of the current control module is used as the input to the current loop control signal. The output 2 of the current control module serves as the input of the id current loop control signal. , Two-phase currents are sampled using a phase current detection circuit, and then transformed using Clarke and Park transformations to obtain the current in the dq rotating coordinate system. and ,Will As the feedback value of the iq current loop, As the feedback value of the id current loop, the input will and The difference is used to obtain the first result; the input will then be... and The difference yields the second result. The first result is output via a current PI controller. The second result is output via a current PI controller. , and Obtained by inverse Park transform and The SVPWM module will input parameters and The voltage is converted into a three-phase ABC stationary coordinate system voltage; the SVPWM module outputs six control signals to drive the inverter, enabling the generator to output the target power. .

[0005] In the dq rotating coordinate system and The calculation formula is:

[0006] .

[0007] Step 1 includes: using the on-chip AD sampling module of the DSP to collect the phase current, subtracting the phase current sampling value from the correction 0 drift and shifting it to the left by 4 bits, and then converting the digital value into an IQ variable of (-1,1) after IQ fast conversion. The IQ variable has 16 decimal places.

[0008] In step 2, the rotor position is calculated according to the rotor position calculation formula. Then adjust the rotor position. With 2 The ratio is used as the rotor position after per unit; rotor position With 2 The range of the ratio is (0,1). The formula for calculating rotor position is:

[0009] in: Position is the current position of the rotor detected by the sensor. Zero is the initial position of the rotor. This represents the number of pole pairs of the motor. The number of pole pairs of the sensor. N represents the sensor's measurement range.

[0010] In step 3, the ratio of the rotor speed to the rated speed of the permanent magnet synchronous motor is used as the per-unit rotor speed, and the range of the per-unit rotor speed is (0,1).

[0011] In step 4, Per unit magnetic flux , Inductance of the d-axis after the unit , Inductance of the q-axis after the unit mark , in, The maximum value of the motor's bus voltage, and the three-phase current at maximum power are (- , ), This is the rated speed.

[0012] The SVPWM module will input parameters. and The voltage is converted to a three-phase static coordinate system (ABC), and the conduction time of the switching transistors is calculated in different zones. The process quantities are expressed using the following formulas: .

[0013] In a second aspect, a per-unit control device for a permanent magnet synchronous motor is provided, which executes the method described in the first aspect, the device comprising: The per-unit module is used for: The phase current is scaled per unit to obtain the phase current after the unit scale; The rotor position is marked per unit to obtain the marked rotor position; The rotor speed is scaled per unit to obtain the per-unit rotor speed. The motor parameters are standardized to per-unit values ​​to obtain the standardized motor parameters, which include: flux linkage. Inductance of the motor's d-axis and q-axis , ; The control module is used to control the permanent magnet synchronous motor based on the phase current, rotor position, rotor speed, and motor parameters after per-unit measurement.

[0014] The beneficial effects of this invention are at least as follows: This invention provides a per-unit control method and device for permanent magnet synchronous motors. It explains the control principle of permanent magnet synchronous motors, focusing on the impact of data flow on control parameters. A per-unit algorithm for current sampling is designed, enabling rapid per-unit scaling of current and voltage through data type conversion. Per-unit algorithms for position and speed are also designed, converting the acquired position signals into per-unit electrical angle and speed signals. Finally, a per-unit algorithm for motor parameters is designed, allowing the per-unit motor parameters to be directly used for feedforward compensation and MTPA control. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the control strategy; Figure 2 This is the flowchart of the per-unit current algorithm; Figure 3 This is a flowchart of the per-unit algorithm for position and rotational speed; Figure 4 This is a flowchart of the per-unit algorithm for motor parameters. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0018] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited from each other.

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] Per-unit control methods can eliminate the influence of differences in size, voltage, and other parameters between different motors, simplifying the design and analysis process. Therefore, this invention provides a per-unit control method for permanent magnet synchronous motors, applicable to the control of different types of motors.

[0021] This invention proposes a per-unit control method for permanent magnet synchronous motors, mainly comprising the following five components: permanent magnet synchronous motor control principle, current sampling per-unit algorithm, position and speed per-unit algorithm, motor parameter per-unit algorithm, and SVPWM per-unit algorithm. The specific implementation design is shown below: 1) Control principle of permanent magnet synchronous motor The permanent magnet synchronous motor control system collects the motor's three-phase current, bus voltage, and rotor position, and outputs three-phase PWM control signals through the motor vector control strategy and SVPWM to control the stable operation of the motor.

[0022] The control motor involved in this invention is a salient-pole synchronous motor, and the overall block diagram of the control strategy is as follows. Figure 1 As shown. The electric angle of the motor is collected by a position sensor. Calculate the motor speed n Given rotational speed The deviation compared to the feedback speed n is processed by a PI controller and used as the input to the current control signal. The output of the current control module is the current command signal for the current loop. , The phase current detection circuit samples the three-phase current and transforms it into the dq rotating coordinate system using Clarke and Park transformations. The current signal in the dq coordinate system is compared with its reference input. and In comparison, the direct-axis voltages are output via a current PI controller. and quadrature axis voltage The result obtained by inverse Park transform and Finally, the inverter is driven by six control signals output from the SVPWM module.

[0023] Figure 1 Medium current control can include id=0 control, MTPA control, and power factor equal to 1 control. id=0 control does not require motor parameters, while MTPA control, for example, does require motor parameters. .

[0024]

[0025]

[0026] For the output of the outer speed loop, it is clear that MTPA control requires the motor's d-axis and q-axis inductance and flux linkage parameters. However, in per-unit algorithm control, the actual parameters cannot be directly applied. For value substitution operations, the parameter values ​​need to be normalized before they can be directly substituted into the operation.

[0027] 2) Per-unit algorithm for current sampling The per-unit control method for permanent magnet synchronous motors does not require the acquisition of bus voltage signals, but the simplification process of the SVPWM control algorithm requires the relationship between voltage signals. The per-unit algorithm flow for current and voltage signals is as follows: Figure 2 , Figure 3 .

[0028] In this embodiment of the invention, the on-chip AD sampling module of the DSP is used to collect the phase current. The phase current sampling value is subtracted from the correction 0 drift and then shifted left by 4 bits. After IQ fast conversion, the digital quantity is converted into an IQ variable of (-1,1).

[0029] The existing SVPWM control algorithm requires the acquired bus voltage, while the per-unit control algorithm does not. The current is calibrated to per unit value and then output via PI control. Since PI control is also per-unit control, the output ranges Ud and Uq are (-1, 1), and the bus voltage range is (0, 1). ).

[0030] 3) Per-unit algorithm for position and rotational speed Per-unit control of permanent magnet synchronous motors requires standardizing the acquired position signal to per unit, and also standardizing the calculated speed signal to per unit.

[0031] The rotor position in the control of a permanent magnet synchronous motor is The formula for calculating the rotor position is:

[0032] in: Potision is the sensor that detects the current position of the rotor. Zero is the initial position of the rotor. This represents the number of pole pairs of the motor. The number of pole pairs of the sensor. N is the sensor rotor position measurement range. Calculated rotor position First convert to Then mark the unit as (0,1).

[0033] If the rated speed of a permanent magnet synchronous motor is n, then the forward rotation speed range is (0, n), and the speed per unit is (0, 1).

[0034] 4) Per-unit algorithm for motor parameters Per-unit control of permanent magnet synchronous motors involves standardizing the acquired signals to per-unit. While basic motor control can be achieved in traditional id=0 vector control, motor parameters need to be standardized to per-unit for MTPA, feedforward, and other controls that require motor parameters.

[0035] The maximum bus voltage of the motor is The three-phase current at maximum power is (- , The rated speed is n, and the magnetic flux of the motor is... The inductance of the motor is , The motor flux linkage after the unit mark is The motor inductance after the per-unit mark is , .

[0036] Then we have the following formula:

[0037]

[0038]

[0039] The motor parameters after per-unit scaling can be directly used in per-unit control algorithms for MTPA or with a power factor of 1.

[0040] 5) SVPWM per-unit algorithm module Existing SVPWM algorithms require bus voltage, while per-unit SVPWM does not. Improvements are made to the traditional algorithm, and the following only describes the changes.

[0041] Existing SVPWM formula:

[0042] Per-unit SVPWM formula: .

[0043] The above description merely illustrates embodiments of the present invention and is quite specific and detailed; however, it should not be construed as limiting the scope of the patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Furthermore, any parts of the present invention not described in detail are conventional techniques.

Claims

1. A per-unit control method for a permanent magnet synchronous motor, characterized in that, The method includes: Step 1: Standardize the phase current by unit to obtain the standardized phase current; Step 2: Standardize the rotor position to obtain the standardized rotor position; calculate the rotor position according to the rotor position calculation formula. Then adjust the rotor position. With 2 The ratio is used as the rotor position after per unit; rotor position With 2 The range of the ratio is (0,1). The formula for calculating rotor position is: in: Position is the current position of the rotor detected by the sensor. Zero is the initial position of the rotor. This represents the number of pole pairs of the motor. The number of pole pairs of the sensor. N represents the sensor's measurement range; Step 3: Standardize the rotor speed per unit to obtain the rotor speed after standardization; Step 4: Standardize the motor parameters to obtain the standardized motor parameters, which include: flux linkage. Inductance of the motor's d-axis and q-axis , ; Step 5: Perform permanent magnet synchronous motor control based on the per-unit phase current, rotor position, rotor speed, and motor parameters; in step 5, the given speed... Feedback rotational speed from position and speed modules n The difference, after being processed by the PI controller, is used as the input to the current control module, and the output 1 of the current control module is used as the input to the current loop control signal. The output 2 of the current control module serves as the input of the id current loop control signal. , Two-phase currents are sampled using a phase current detection circuit, and then transformed using Clarke and Park transformations to obtain the current in the dq rotating coordinate system. and ,Will As the feedback value of the iq current loop, As the feedback value of the id current loop, the input will and The difference is used to obtain the first result; the input will then be... and The difference yields the second result. The first result is output via a current PI controller. The second result is output via a current PI controller. , and Obtained by inverse Park transform and The SVPWM module will input parameters and The voltage is converted into a three-phase ABC stationary coordinate system voltage. The SVPWM module outputs six control signals to drive the inverter, enabling the generator to output the target power. .

2. The method according to claim 1, characterized in that, In the dq rotating coordinate system and The formula for calculating is: 。 3. The method according to claim 1, characterized in that, Step 1 includes: using the on-chip AD sampling module of the DSP to acquire the phase current, subtracting the phase current sampling value from the correction 0 drift and shifting it to the left by 4 bits, and then performing IQ fast conversion to convert the digital value into an IQ variable of (-1,1), with 16 decimal places for the IQ variable.

4. The method according to claim 1, characterized in that, In step 3, the ratio of the rotor speed to the rated speed of the permanent magnet synchronous motor is taken as the per-unit rotor speed, and the range of the per-unit rotor speed is (0,1).

5. The method according to claim 1, characterized in that, In step 4, Per unit magnetic flux , Inductance of the d-axis after the unit , Inductance of the q-axis after the unit mark , in, The maximum value of the motor's bus voltage, and the three-phase current at maximum power are (- , ), This is the rated speed.

6. The method according to claim 1, characterized in that, The SVPWM module will input parameters and The voltage is converted to a three-phase static coordinate system (ABC), and the conduction time of the switching transistors is calculated in different zones. The process quantities are expressed using the following formulas: 。 7. A per-unit control device for a permanent magnet synchronous motor, characterized in that, The apparatus for performing the method of claim 1 includes: The per-unit module is used for: The phase current is scaled per unit to obtain the phase current after the unit scale; The rotor position is marked per unit to obtain the marked rotor position; Standardize the rotor speed per unit to obtain the per-unit rotor speed; The motor parameters are standardized to per-unit values ​​to obtain the standardized motor parameters, which include: flux linkage. Inductance of the motor's d-axis and q-axis , ; The control module is used to control the permanent magnet synchronous motor based on the phase current, rotor position, rotor speed, and motor parameters after per-unit measurement.

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