CN105071731A - Efficient acceleration control method for permanent-magnet synchronous motor - Google Patents

Abstract

The invention relates to a high-efficiency acceleration control method for a permanent magnet synchronous motor, comprising the following steps: detecting the rotational speed of the permanent magnet synchronous motor in real time, and comparing it with a target rotational speed; The magnetic synchronous motor enters the high-efficiency acceleration control mode, so that the torque shaft current i _q reaches the maximum stator current value i _lim under the limitation of the inverter and the permanent magnet synchronous motor, so as to obtain the maximum electromagnetic torque, so that the motor has been operating at the maximum The acceleration approaching the target speed, the above is the open-loop control stage; when the motor speed reaches k times the target speed and above, the permanent magnet synchronous motor exits the high-efficiency acceleration control mode, enters the stable control mode, and switches to i _d = 0 Under the vector control strategy, the permanent magnet synchronous motor enters the double closed-loop control of current and speed, so that the motor can approach the target speed more smoothly and the system can run stably at the desired speed. The method can reach the target speed as soon as possible when the permanent magnet synchronous motor is started or when the predetermined speed changes greatly, greatly shortening the acceleration time of the motor; and the structure is simple and easy to realize.

Description

A high-efficiency acceleration control method for permanent magnet synchronous motors

technical field

The invention belongs to the technical field of motor control, and relates to a high-efficiency acceleration control method for a permanent magnet synchronous motor.

Background technique

With the emergence of new power electronic devices GTO, IGBT, etc., the synchronous motor speed control system has developed to a new stage. The permanent magnet synchronous motor speed control system has good static and dynamic characteristics and is suitable for use in machine tools, robots and flexible manufacturing systems. middle. The rotor of the motor is excited by permanent magnets, which eliminates the loss of rotor excitation. Nowadays, permanent magnet synchronous motors are widely used because of their advantages such as convenient maintenance, strong controllability, low environmental impact, high motor efficiency, and high power factor. Permanent magnet synchronous motors are developing towards high power, high speed, high efficiency and miniaturization. Today's world has developed a small permanent magnet synchronous motor with a power density exceeding 1KW/kg and a rated efficiency greater than 90%, and it meets the traction control requirements of low-speed high-torque and high-speed constant power.

The classic motor control methods mainly include: vector control, direct torque control double closed-loop control, the speed loop and current loop of vector control adopt classic PI control at the same time; modern control theory mainly adds sliding mode variable structure control to the speed loop and current loop ; Intelligent control theory adds fuzzy control, neural network, expert system and other control strategies in the double closed loop.

However, various existing motor control strategies still have various deficiencies. The algorithm structure of vector control technology is relatively complex, and it is necessary to decouple the AC and DC axis currents of the motor. It is difficult to implement and requires relatively high requirements for the controller. , and its response to speed is slow, and its anti-interference ability is poor; direct torque control technology has poor speed regulation performance at low speeds; modern control theory and intelligent control research mostly stay at the theoretical stage.

Contents of the invention

In view of this, the object of the present invention is to provide a high-efficiency acceleration control method for a permanent magnet synchronous motor, which can accelerate its response to speed based on a vector control strategy.

To achieve the above object, the present invention provides the following technical solutions:

A high-efficiency acceleration control method for a permanent magnet synchronous motor, comprising the following steps:

Step 1, real-time detection of the actual speed ω _t of the permanent magnet synchronous motor and return to the system;

Step 2. Comparing the actual speed of the motor with the k (k≤1) times of the target speed ω _r , determine the control mode of the permanent magnet synchronous motor: high-efficiency acceleration control mode or stable control mode;

Step 3. If ω _t <kω _r , the motor enters the high-efficiency acceleration control mode, and the torque axis current i _q is the maximum stator current value i _lim under hardware constraints such as the inverter and the permanent magnet synchronous motor itself. The regulator outputs the torque shaft voltage u _qref , which is input to the SVPWM module after Park transformation, and the SVPWM module outputs six PWM waves to control the inverter IGBT, so that it can output the three-phase current at the maximum electromagnetic torque, so that the motor can obtain the maximum electromagnetic Torque, so that the motor approaches the target speed with the maximum acceleration that can be achieved. This stage is open-loop control;

Step 4. When the motor speed reaches k times or more than the target speed, that is, when ω _t ≥ kω _r , the motor exits the high-efficiency acceleration control mode, enters the stable control mode, and switches to the vector control strategy with i _d = 0 to form a speed The double closed-loop control system of current and current, the system returns the actual speed ω _t and the target speed ω _r to form an error amount, the initial value i _qref of the torque axis current is output by the speed controller, and the current error value is formed by i _qref and the current return value, and then After being adjusted by the current regulator, the output torque axis voltage u _qref is input to the SVPWM module through Park transformation, and the SVPWM module outputs six PWM waves to control the inverter IGBT to output three-phase current, so that the motor can approach the target speed more smoothly. This stage is a closed loop control;

Step 5. The permanent magnet synchronous motor is finally stabilized at the target speed, and the system has been running in a stable control mode. If the operating condition of the permanent magnet synchronous motor changes, the system can also make rapid adjustments under closed-loop control, and the system runs in a stable state. .

Further, in step 1, a sensor is used to detect the actual rotational speed of the motor in real time and return it to the control system.

Further, in step 2, the value of k (k≤1) is set according to hardware equipment conditions and different requirements of different uses of the permanent magnet synchronous motor, so as to meet various different requirements.

Further, in step three, the maximum stator current i _lim is set according to the hardware conditions of the inverter and the permanent magnet synchronous motor itself.

Further, in steps 3 and 4, the torque axis current and the magnetic flux current are controlled by the vector control algorithm; the values of k and i _lim only need to be set once for the system.

The beneficial effect of the present invention is that: at the beginning of permanent magnet synchronous motor start-up or when the target speed changes greatly, there is a large difference between the actual speed of the motor and the target speed, and the existing vector control system has the disadvantage of slow response speed, The present invention can accelerate the response speed on the basis of vector control, accelerate with the maximum acceleration that can be achieved under hardware conditions, greatly shorten the acceleration time of the motor, and adapt to various needs of motors for different purposes under different working conditions.

Description of drawings

In order to make the purpose, technical scheme and beneficial effect of the present invention clearer, the present invention provides the following drawings for illustration:

Fig. 1 is a flow chart of a high-efficiency acceleration control method for a permanent magnet synchronous motor;

Fig. 2 is the structural block diagram of the efficient acceleration control method of the permanent magnet synchronous motor in the embodiment;

Fig. 3 adopts the motor speed simulation curve under common vector control method in the embodiment;

Fig. 4 is the simulation curve of the motor speed under the high-efficiency acceleration control method in the embodiment;

Fig. 5 adopts the motor torque shaft current emulation curve under common vector control method in the embodiment;

Fig. 6 is the simulation curve of the torque shaft current of the motor under the high-efficiency acceleration control method in the embodiment.

Detailed ways

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in Figure 1 and Figure 2, the flow chart and structural block diagram of the high-efficiency acceleration control method of the permanent magnet synchronous motor of the present invention, the specific steps of the method of the present invention are as follows:

First define the following parameter quantities:

In this embodiment, the set values of the system parameters are: target speed ω _r =2500r/min, k=0.7, stator limit current i _lim =95A.

Step (a): Detect the position information of the motor through the sensor, and then differentiate the position information with respect to time to obtain the actual speed ω _t of the motor and bring it back into the system;

Step (b): compare ω _t with k times kω _r of the system input speed, where kω _r = 1750r/min, determine the control mode of the permanent magnet synchronous motor, the efficient acceleration control mode or the stable control mode;

Step (c): If kω _r <1750r/min; the motor enters the high-efficiency acceleration control control mode, as shown in Figure 2, let the torque axis current i _q = 95A, output the torque axis voltage u _qref through the current regulator, Input the SVPWM module through Park transformation, the SVPWM module outputs six PWM waves to control the inverter IGBT to output three-phase current, so that the motor can obtain the maximum electromagnetic torque, and the motor can approach the target speed with the maximum acceleration that can be achieved. This stage is an open loop control;

Step (d): After the motor accelerates for a period of time, the speed reaches k times or more than the target speed, that is, when ω _t ≥ 1750r/min, as shown in Figure 2, the motor exits the high-efficiency acceleration control mode and enters the stable control mode, Switch to the vector control strategy with i _d = 0 to form a double closed-loop control system of speed and current. The system returns the actual speed ω _t and the target speed ω _r to form an error amount, and the initial value of the torque shaft current i _qref is output by the speed controller , i _qref and the current return value form a current error value, and then adjusted by the current regulator, the output torque shaft voltage u _qref is input to the SVPWM module after Park transformation, and the SVPWM module outputs six PWM waves to control the inverter IGBT to output three-phase current, Make the motor approach the target speed more smoothly, this stage is closed-loop control;

Step (e): The permanent magnet synchronous motor is finally stabilized at the target speed, and the system has been running in the stable control mode. If the operating condition of the permanent magnet synchronous motor changes, the system can also make rapid adjustments under closed-loop control, and the system is stable. state operation.

As shown in FIG. 2 , the structural block diagram of the control method implemented in the present invention mainly includes: a control mode judgment module, a coordinate transformation module, an SVPWM module, a current controller and other main modules.

Both the speed controller and the current controller in the specific example of the present invention adopt the PI control method.

Figure 3 and Figure 4 are the speed simulation curves of the ordinary vector control mode and the high-efficiency acceleration control mode respectively. As shown in Figure 3, in the ordinary vector control mode, starting from the motor start, after 0.79s acceleration to reach the target speed of 2500r/min, as As shown in Fig. 4, under the high-efficiency acceleration control mode, the motor reaches the target speed of 2500r/min after 0.44s of acceleration, and the beneficial effect of the present invention can be clearly reflected by comparison. Fig. 5 is the simulation curve of the motor torque shaft current under the common vector control method in the embodiment, and Fig. 6 is the simulation curve of the motor torque shaft current under the high-efficiency acceleration control method in the embodiment.

Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that it can be described in terms of form and Various changes may be made in the details without departing from the scope of the invention defined by the claims.

Claims (5)

1. A high-efficiency acceleration control method for permanent magnet synchronous motors, characterized in that: comprises the following steps: Step 1, real-time detection of the actual speed ω _t of the permanent magnet synchronous motor and return to the system; Step 2. Comparing the actual speed of the motor with the k (k≤1) times of the target speed ω _r , determine the control mode of the permanent magnet synchronous motor: high-efficiency acceleration control mode or stable control mode; Step 3. If ω _t <kω _r , the motor enters the high-efficiency acceleration control mode, and the torque axis current i _q is the maximum stator current value i _lim under hardware constraints such as the inverter and the permanent magnet synchronous motor itself. The regulator outputs the torque shaft voltage u _qref , which is input to the SVPWM module after Park transformation, and the SVPWM module outputs six PWM waves to control the inverter IGBT, so that it can output the three-phase current at the maximum electromagnetic torque, so that the motor can obtain the maximum electromagnetic Torque, so that the motor approaches the target speed with the maximum acceleration that can be achieved. This stage is open-loop control; Step 4. When the motor speed reaches k times or more than the target speed, that is, when ω _t ≥ kω _r , the motor exits the high-efficiency acceleration control mode, enters the stable control mode, and switches to the vector control strategy with i _d = 0 to form a speed The double closed-loop control system of current and current, the system returns the actual speed ω _t and the target speed ω _r to form an error amount, the initial value i _qref of the torque axis current is output by the speed controller, and the current error value is formed by i _qref and the current return value, and then After being adjusted by the current regulator, the output torque axis voltage u _qref is input to the SVPWM module through Park transformation, and the SVPWM module outputs six PWM waves to control the inverter IGBT to output three-phase current, so that the motor can approach the target speed more smoothly. This stage is a closed loop control; Step 5. The permanent magnet synchronous motor is finally stabilized at the target speed, and the system has been running in a stable control mode. If the operating condition of the permanent magnet synchronous motor changes, the system can also make rapid adjustments under closed-loop control, and the system runs in a stable state. . 2. A method for high-efficiency acceleration control of a permanent magnet synchronous motor according to claim 1, characterized in that: in step 1, the actual rotational speed of the motor is detected in real time by a sensor and returned to the control system. 3. The efficient acceleration control method of a permanent magnet synchronous motor according to claim 1, characterized in that: in step 2, the value of k (k≤1) is different according to the hardware equipment conditions and the different purposes of the permanent magnet synchronous motor Requirements are set to respond to a variety of different needs. 4. The efficient acceleration control method of a permanent magnet synchronous motor according to claim 1, characterized in that: in step 3, the stator maximum current i _lim is set according to the hardware conditions of the inverter and the permanent magnet synchronous motor itself . 5. A high-efficiency acceleration control method for a permanent magnet synchronous motor according to claim 1, characterized in that: in steps 3 and 4, the torque axis current and the flux current are controlled by a vector control algorithm.