A method for dynamically coupling and correcting the current of a permanent magnet synchronous motor

Abstract

The present invention discloses a method for correcting the dynamic coupling of the current of a permanent magnet synchronous motor, comprising the following steps: collecting the three-phase stator current of the motor and performing Clark transformation to obtain α‑β The current value in the static coordinate system is collected by the position sensor to obtain the real value of the electrical angle; α‑β The current value in the static coordinate system is low-pass filtered to obtain a filtered current value, which is then used through a sliding mode observer and a phase-locked loop (PLL) to obtain the observed electrical angle value. A compensation adjustment coefficient is calculated based on the actual electrical angle value and the observed value, and the current value after phase offset compensation is further calculated. The filtered current value and the current value after phase offset compensation are then subjected to complementary filtering to obtain a coupled correction current value for current loop calculation. This current value is then input into the motor control current loop PID algorithm, and combined with vector control to generate a PWM drive signal to drive the motor. This method can address high-frequency interference and phase offset issues in current sampling, thereby improving motor control efficiency and dynamic performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of permanent magnet synchronous motor drive control, and in particular relates to a method for correcting the dynamic coupling of current in a permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motors (PMSMs), with their exceptional high power density and high efficiency, have found widespread application in numerous key sectors. In electric vehicles, they provide robust and efficient power output, enabling longer range and superior acceleration. In rotary-wing drones (UAVs), their lightweight and high efficiency ensure stable flight and extend flight time. In industrial drives, the high precision and reliability of PMSMs meet the stringent operational standards of industrial production.

[0003] However, traditional control methods have many drawbacks in the application of permanent magnet synchronous motors. They are highly dependent on current sensors, which leads to a series of problems:

[0004] First, regarding dynamic performance, traditional control methods decouple the current loop from the position observer. This design approach results in significant lag in the system's dynamic response when faced with complex dynamic conditions. For example, when the motor needs to rapidly change speed or the load suddenly changes, the system cannot make precise adjustments in time, thus affecting the motor's overall operating efficiency and stability.

[0005] Secondly, speed fluctuation is a prominent issue. The current loop sampling process inevitably introduces high-frequency interference, which is transmitted to the speed control link, causing unstable fluctuations in the motor speed. This fluctuation not only reduces the smoothness of the motor's operation but can also damage connected equipment.

[0006] Finally, inefficiency is a major drawback of traditional control methods. Phase deviation in the current loop significantly increases reactive power losses during motor operation. This additional loss not only wastes energy but also directly impacts the overall efficiency of the permanent magnet synchronous motor, increasing operating costs. Summary of the Invention

[0007] In response to the shortcomings of the existing technology, the present invention proposes a method for correcting the dynamic coupling of current in a permanent magnet synchronous motor. The method combines vector control to generate a PWM drive signal to drive and control the motor rotation, solve the high-frequency interference and phase offset problems of current sampling, and thus improve the motor control efficiency and dynamic performance.

[0008] The present invention is achieved through the following technical solutions:

[0009] A method for correcting the dynamic coupling of current in a permanent magnet synchronous motor comprises the following steps:

[0010] The three-phase stator current of the motor is collected by the current sensor during the electrical angle sampling period. i a 、 i b 、 i c , obtained by Clarke transformation α-β Current value in static coordinate system 、 At the same time, the real value of the electrical angle is obtained by collecting the position sensor ;

[0011] Will α-β Current value in static coordinate system 、 After low-pass filtering, the filtered current value is obtained By constructing a sliding mode observer and a PLL phase-locked loop, the electrical angle observation value is calculated ;

[0012] According to the true value of the electrical angle With the observed value Calculate the compensation adjustment coefficient M 1. The calculation formula is as follows:

[0013] ;

[0014] in ;

[0015] Will α-β Current value in static coordinate system 、 and compensation adjustment coefficient The current value after phase offset compensation is obtained by the following calculation: :

[0016] ;

[0017] Filter current value Current value after phase offset compensation Perform complementary filtering calculations to obtain the coupling correction current value used for current loop calculations :

[0018] ;

[0019] The final coupled correction current value It is brought into the motor control current loop PID algorithm and combined with vector control to generate a PWM drive signal to drive and control the motor rotation.

[0020] further, α-βCurrent value in static coordinate system 、 After low-pass filtering, the filtered current value is obtained :

[0021] ;

[0022] in 、 Indicates the current round of collection α-β Current value in static coordinate system, 、 Indicates the last round of collection α-β For the current value in the static coordinate system, the filter coefficient a ranges from 0.9 to 0.95.

[0023] Furthermore, the sliding mode observer construction process is as follows:

[0024] According to the motor α-β The static coordinate voltage calculation relationship yields the following current state equation:

[0025] ;

[0026] in R s stator resistance, L is the stator inductance, for α-β Stator current value in static coordinate system 、 After low-pass filtering, the filtered current value is obtained. u α 、 u β for α-β Stator voltage in the static coordinate system, E α 、 E β Shown as α-β Back electromotive force in the static coordinate system, is the fixed value of the motor flux, is the current motor speed, is the true value of the electrical angle collected by the position sensor, is the electrical angle sampling period, is the true value of the electrical angle collected in the current round, The actual value of the electrical angle collected in the previous round;

[0027] The sliding mode observer equation is constructed from the current state equation:

[0028] ;

[0029] in To observe the current, As the observer input, let:

[0030] ;

[0031] in h is the back EMF gain value, sign (·) is the sign function;

[0032] Comparing the error between the filtered current and the observed current, subtract equation (1) from equation (4) to obtain the following equation:

[0033] ;

[0034] in represents the current observation error, which serves as the sliding surface of the sliding film observer.

[0035] The present invention also provides a computer program product, comprising a computer program / instructions, which implement the steps of the method described above when executed by a processor.

[0036] The present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described above are implemented.

[0037] The present invention also provides an electronic device, comprising a processor, a memory, and a computer program stored in the memory and capable of running on the processor, wherein the computer program implements the steps of the method described above when executed by the processor.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The technical solution of the present invention aims to dynamically compensate and correct the static coordinate system current value used in the current loop through the electrical angle observation value, eliminate the high-frequency interference and phase offset present in the current sampling, improve the real-time dynamic response of the motor speed and the ability to resist disturbances and suppress speed fluctuations, thereby improving the motor performance and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Flow chart of the steps for implementing the method of the present invention;

[0041] Figure 2 Schematic diagram of a phase-locked loop according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art. It should be noted that, unless there is a conflict, the embodiments of the present invention and the features within the embodiments may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0043] The present invention provides an embodiment of a method for correcting the dynamic coupling of current in a permanent magnet synchronous motor. A real-world test is conducted using a motor of a UAV with a rotor blade. The process is as follows: Figure 1 The specific steps are as follows:

[0044] Step 1: When the controller is powered on, the controller software completes the power-on initialization program phase. At this time, it sends the motor start and target rotation speed instructions. The controller executes the response and generates ABC three-phase PWM output, so that the synchronous motor rotates to the given speed and maintains the current speed. At this time, the current real-time electrical angle value is collected through the magnetic encoder. , collect the current ABC three-phase current value through the current sensor i a 、 i b 、 i c .

[0045] Step 2: Run the program that contains the current sliding mode observer equation and the sliding mode gain adjustment law code, and calculate the electrical angle observation value through the sliding mode observer and PLL phase-locked loop. , where the current sliding mode observer is constructed as follows:

[0046] The three-phase current value of the motor is converted to α-β Static coordinate system, according to the motor α-β The static coordinate voltage calculation relationship yields the following current state equation:

[0047] ;

[0048] in R s stator resistance, L is the stator inductance, for α-β Stator current value in static coordinate system 、 After low-pass filtering, the filtered current value is obtained. u α 、 uβ for α-β Stator voltage in the static coordinate system, E α 、 E β Shown as α-β Back electromotive force in the static coordinate system, is the fixed value of the motor flux, is the current motor speed, is the true value of the electrical angle collected by the position sensor, is the electrical angle sampling period, is the true value of the electrical angle collected in the current round, It is the actual value of the electrical angle collected in the previous round.

[0049] The sliding mode observer equation is constructed from the current state equation:

[0050] ;

[0051] in To observe the current, As the observer input, let:

[0052] ;

[0053] in h is the back EMF gain value, sign (·) is a sign function. If the input in the brackets is greater than 0, the function value is equal to 1. Otherwise, if the input is less than 0, the function value is equal to -1.

[0054] Comparing the error between the filtered current and the observed current, subtract equation (1) from equation (4) to obtain the following equation:

[0055] ;

[0056] in is the current observation error, that is, the sliding surface. At this point, the sliding film observer is established.

[0057] The sliding mode gain regulation law is designed based on the general sliding mode surface function, and the appropriate h The value makes the sliding surface converge and remain at 0, that is, the current observation error is 0. At this time, we can get:

[0058] ;

[0059] Substituting the observer control input equation (4) into the above equation, we can obtain:

[0060] ;

[0061] Build a phase-locked loop by 、 As the input of the phase-locked loop, the two inputs are respectively compared with the phase-locked loop output feedback value 、 The product is then compared and the difference is made to form the phase detector link of the phase-locked loop, and the output of the phase detector is then The PI regulator is brought in for operation to form the low-pass filter and voltage-controlled oscillator link of the phase-locked loop, thereby obtaining the phase-locked loop output feedback value , and finally form a complete closed loop, the phase-locked loop can work normally, where the PI controller parameters K P 、 K I It needs to be obtained through integration calculation of the motor's maximum speed frequency range and magnetic flux data.

[0062] The back electromotive force of formula (2) Bring in Figure 2 In the PLL phase-locked loop shown in FIG, the formula is as follows:

[0063] ;

[0064] From the above formula, we can know that the phase-locked loop obtains The estimated electrical angle observation value is obtained by directly bringing the sliding mode observer output in formula (8) into the phase-locked loop. .

[0065] The above sliding mode controller algorithm is written into the execution program code in a discrete manner, the MCU timer is configured to set the sampling period Ts, and the three-phase current is collected through the current sensor. i a 、 i b 、 i c , obtained by Clarke transformation α-β Current value in static coordinate system 、 ,Will α-β Current value in static coordinate system 、 After low-pass filtering, the filtered current value is obtained :

[0066] ;

[0067] Step 3: Use the actual value of the electrical angle The electrical angle estimate obtained by the observer phase-locked loop Do the difference and get the phase offset:

[0068] ;

[0069] The electrical angle phase offset value Substitute into the following formula to calculate the current compensation adjustment coefficient :

[0070] ;

[0071] Step 4: α-β Current value in static coordinate system 、 and compensation adjustment coefficient The current value after phase offset compensation is obtained by the following calculation: :

[0072] ;

[0073] Filter current value The current value after phase offset compensation Perform complementary filtering coupling correction to finally obtain the coupling correction current value used for current loop calculation :

[0074] ;

[0075] ;

[0076] Step 5: The final coupling corrected value It is brought into the motor control current loop PID algorithm and combined with vector control to generate a PWM drive signal to drive and control the motor rotation.

[0077] All of the above steps are pre-programmed into the running program. After power is applied and the commands and calculations are executed, a PWM signal is generated to drive the motor. The code is written using CCS software on a PC, compiled, and then downloaded to the DSP chip for execution.

[0078] The comparison of the application effect of the UAV rotor motor blade drive test is shown in Tables 1 and 2. Under the same throttle condition, the motor speed is increased by about 3%-5% after the current dynamic coupling correction of the present invention is adopted, and the overall efficiency is increased by 2%-4%.

[0079] Table 1 Motor drive operating conditions without current coupling correction

[0080]

[0081] Table 2 Motor drive conditions using the current dynamic coupling correction of the present invention

[0082]

[0083] The above method is embedded in the motor controller through code programming, which significantly improves the motor control response performance and system efficiency. The technical solution of the present invention is also applicable to high-dynamic scenarios such as electric vehicles and industrial servos.

[0084] The present invention has been described in detail above through the embodiments, but the contents described are only exemplary embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. The scope of protection of the present invention is defined by the claims. Any use of the technical solution described in the present invention, or any person skilled in the art who, inspired by the technical solution of the present invention, designs a similar technical solution within the essence and scope of protection of the present invention to achieve the above-mentioned technical effects, or any equivalent changes and improvements made to the scope of application, shall still fall within the scope of protection covered by the patent of the present invention. It should be noted that for the sake of clarity, the description of some components and processes that have no direct and obvious connection with the scope of protection of the present invention but are known to those skilled in the art are omitted in the description of the present invention.

Claims

1. A method for correcting the dynamic coupling of current in a permanent magnet synchronous motor, characterized in that: The following steps are involved: The three-phase stator current of the motor is collected by the current sensor during the electrical angle sampling period. i a 、 i b 、 i c , obtained by Clarke transformation α-β Current value in static coordinate system 、 At the same time, the real value of the electrical angle is obtained by collecting the position sensor ; Will α-β Current value in static coordinate system 、 After low-pass filtering, the filtered current value is obtained By constructing a sliding mode observer and a PLL phase-locked loop, the electrical angle observation value is calculated ; According to the true value of the electrical angle With the observed value Calculate the compensation adjustment coefficient M 1. The calculation formula is as follows: ； in ; Will α-β Current value in static coordinate system 、 and compensation adjustment coefficient The current value after phase offset compensation is obtained by the following calculation: : ； Filter current value Current value after phase offset compensation Perform complementary filtering calculations to obtain the coupling correction current value used for current loop calculations : ； The final coupled correction current value It is brought into the motor control current loop PID algorithm and combined with vector control to generate a PWM drive signal to drive and control the motor rotation.

2. The method according to claim 1, characterized in that α-β Current value in static coordinate system 、 After low-pass filtering, the filtered current value is obtained : ； in 、 Indicates the current round of collection α-β Current value in static coordinate system, 、 Indicates the last round of collection α-β For the current value in the static coordinate system, the filter coefficient a ranges from 0.9 to 0.

95.

3. The method according to claim 2, characterized in that The sliding mode observer construction process is as follows: According to the motor α-β The static coordinate voltage calculation relationship yields the following current state equation: ； in R s stator resistance, L is the stator inductance, for α-β Stator current value in static coordinate system 、 After low-pass filtering, the filtered current value is obtained. u α 、 u β for α-β Stator voltage in the static coordinate system, E α 、 E β Shown as α-β Back electromotive force in the static coordinate system, is the fixed value of the motor flux, is the current motor speed, is the true value of the electrical angle collected by the position sensor, is the electrical angle sampling period, is the true value of the electrical angle collected in the current round, The actual value of the electrical angle collected in the previous round; The sliding mode observer equation is constructed from the current state equation: ； in To observe the current, As the observer input, let: ； in h is the back EMF gain value, sign (·) is the sign function; Comparing the error between the filtered current and the observed current, subtract equation (1) from equation (4) to obtain the following equation: ； in Represents the current observation error, which serves as the sliding surface of the sliding mode observer.

4. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 3 are implemented.

5. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 3 are implemented.

6. An electronic device, characterized in that: The method comprises a processor, a memory, and a computer program stored in the memory and capable of running on the processor, wherein the computer program implements the steps of the method according to any one of claims 1 to 3 when executed by the processor.

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