KR20070076854A - Start control method of sensorless permanent magnet synchronous motor - Google Patents

Abstract

The present invention relates to a start control method of a sensorless permanent magnet synchronous motor, and aims to minimize start failure when starting a permanent magnet synchronous motor without a sensor in a system with a large load fluctuation.

To this end, the present invention provides a method of starting a permanent magnet synchronous motor through sensorless vector control, comprising: forcibly aligning the permanent magnet synchronous motor by increasing the rotational coordinate system d-axis current command value of the vector control by a predetermined slope; Forcibly starting the permanent magnet synchronous motor by decreasing the rotational coordinate system d-axis current command value of the vector control by a constant slope after the forced alignment; And controlling the x-axis of the crossover function that mixes the position and velocity information estimated by the mechanical model and the position and velocity information estimated by the electrical model after the forced start is started based on the position information estimated by the mechanical model. To include the steps.

Description

Method to control starting of sensorless Permanent Magnet Synchronous Motor

1 is a start control pattern diagram of a conventional sensorless permanent magnet synchronous motor,

2 is a block diagram for estimating position and velocity information with a mechanical model of a general sensorless permanent magnet synchronous motor;

3 is a waveform diagram of a start-up experiment of a conventional sensorless permanent magnet synchronous motor,

4 is a speed control configuration diagram of a sensorless permanent magnet synchronous motor according to the present invention;

5 is a configuration diagram of a general vector current controller,

6 is a start control pattern diagram of a sensorless permanent magnet synchronous motor according to the present invention;

7 is a diagram illustrating a d-axis and q-axis current command value calculation algorithm when starting the sensorless permanent magnet synchronous motor of the present invention;

8 is a crossover function of a sensorless permanent magnet synchronous motor according to the present invention;

9 shows position information used for the estimated position and control at the start of the sensorless permanent magnet synchronous motor;

Figure 10 is a waveform diagram of the starting experiment of the sensorless permanent magnet synchronous motor of the present invention.

* Description of the symbols for the main parts of the drawings *

10: permanent magnet synchronous motor 20: inverter

30: current estimation 40,50: first and second position speed estimator

60: position speed mixer 70: speed controller

80: current command converter 90: vector current controller

The present invention relates to a start control of a sensorless permanent magnet synchronous motor, and more particularly to a start control method of a sensorless permanent magnet synchronous motor which minimizes a start failure when starting a permanent magnet synchronous motor without a sensor.

In general, a stator of a permanent magnet synchronous motor uses an armature that forms a current through a coil, and a rotor uses a permanent magnet formed by repeating the N pole and the S pole. In order for the permanent magnet synchronous motor to rotate continuously, it is necessary to form a continuous rotor field of the permanent magnet synchronous motor.To form a continuous rotor field, the commutation of the current flowing through each phase coil of the armature is performed at an appropriate time. In order to make the proper switchover, the position of the rotor must be accurately recognized.

The changeover here is to change the current direction of the motor stator coils so that the rotor can rotate.

In order to operate the permanent magnet synchronous motor smoothly, the position of the rotor and the switching point of the phase current must be precisely matched, and for this purpose, a device for detecting the position of the rotor is required. For this, position detection sensors such as Hall sensors, resolver elements, and encoders are used.

Since the position detection sensor is expensive to manufacture and the compressor cannot be used for the permanent magnet synchronous motor due to environmental problems such as the temperature inside the compressor, the position of the rotor is determined by using the voltage and current information of the permanent magnet synchronous motor. Sensorless control methods that detect indirectly have been sought.

Since the sensorless permanent magnet synchronous motor does not have a sensor and does not know the initial position of the rotor, a forced starting method is adopted. In order to drive a permanent magnet synchronous motor without a sensor, the motor is forcedly aligned by supplying a d-axis current at an electric angle of 0 degrees like the forced alignment section of FIG. 1, and after a predetermined time, the position and position estimated by the mechanical model of FIG. Forced start using speed information. After starting by mixing the position and speed information and the crossover function estimated by the electrical model, and then switch to the sensorless section to drive the motor.

However, the sensorless permanent magnet synchronous motor has a position and speed estimated by the machine model during forced start after forced alignment because the forced alignment of the motor is not performed precisely due to the load change when the forced alignment is performed under the condition that the load varies greatly. When starting the motor by using the information, the actual value is not correct and there is a high possibility of starting failure.

That is, as soon as the d-axis current is directly applied as shown in FIG. 1, the motor may be shaken to increase the time for forced alignment according to the motor load. If is large, it can move in the forced alignment position. If the motor moves after the forced alignment, the forced start will fail.

In addition, after the forced start is successful, the position and velocity information estimated by the electric model and the position and velocity information estimated by the mechanical model are mixed and used as a crossover function. The problem is that the actual speed and the speed setpoint are not always the same, which can cause the maneuver to fail.

3 illustrates an experimental waveform when starting the conventional sensorless permanent magnet synchronous motor. FIG. 3 shows experimental waveforms of the phase A current when the d-axis command value is directly applied during forced alignment and the phase A current when the d-axis command value is directly applied to '0' during forced start. As can be seen, it can be seen that the motor shaft is greatly shaken during forced alignment and the motor shaft is momentarily shaken when the load is large during forced startup, and the start may fail.

Accordingly, the present invention is to solve the conventional problems as described above, an object of the present invention is to provide a sensorless permanent magnet synchronous motor to minimize the start failure when starting the permanent magnet synchronous motor without a sensor in a large load fluctuation system It is to provide a start control method.

In order to achieve the above object, the present invention provides a method of starting a permanent magnet synchronous motor through sensorless vector control, and forcibly aligns the permanent magnet synchronous motor by increasing the rotational coordinate system d-axis current command value of the vector control by a predetermined slope. Making a step; And forcibly starting the permanent magnet synchronous motor by decreasing the rotational coordinate system d-axis current command value of the vector control by a constant slope after forced alignment.

In addition, the present invention provides the position information estimated by the machine model on the x-axis of the crossover function that mixes the position and velocity information estimated by the machine model and the position and velocity information estimated by the electric model after the forced start is started. It characterized in that it further comprises the step of controlling by reference.

In addition, the present invention provides a method of starting a permanent magnet synchronous motor through sensorless vector control, wherein the d-axis current command value of the rotational coordinate system of the vector control is increased by a predetermined slope during forced alignment of the permanent magnet synchronous motor. It features.

In addition, the present invention is a method of starting the permanent magnet synchronous motor through the sensorless vector control, the reduction of the rotational coordinate system d-axis current command value of the vector control applied by a constant slope when the permanent magnet synchronous motor is forcibly started. It features.

In addition, the d-axis current command value is applied by an arbitrary equation of the rotation coordinate system d-axis current and q-axis current of the vector control when the permanent magnet synchronous motor is forcibly started.

In addition, the present invention is a method for starting the permanent magnet synchronous motor through the sensorless vector control, after the forced start of the permanent magnet synchronous motor is started, the position and the speed information estimated by the mechanical model and estimated by the electrical model And controlling the x-axis of the crossover function that mixes the estimated position and velocity information based on the position information estimated by the machine model.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

4 is a speed control configuration diagram of a sensorless permanent magnet synchronous motor according to the present invention, and FIG. 5 is a configuration diagram of a general vector current controller.

4, the speed control device of the sensorless permanent magnet synchronous motor of the present invention is a voltage source inverter 20 for supplying a three-phase voltage to the permanent magnet synchronous motor 10, the current estimator 30 according to the application of the phase voltage, A first position velocity estimator 40 based on an electrical model estimating position and velocity using counter electromotive force and magnetic flux, and a machine model based on a mechanical model estimating position and velocity using the inertia coefficient and torque of the rotor. 2 position velocity estimator 50, a position velocity mixer 60 for mixing the position and velocity information estimated by the electrical model and the position and velocity information estimated by the mechanical model with a crossover function, and the measured or estimated velocity and Speed controller 70 that generates a torque command by comparing the command, Current command converter 80 that converts the torque command into a current command, and Vector electric field that generates voltage by comparing the command current with the estimated and measured current. And a controller (90).

The current estimator 30 may be configured in various forms. The three-phase current is directly detected by using three current transducers or a series shunt resistor in three phases of the first permanent magnet synchronous motor 10. Second, two current converters or series shunt resistors detect the two-phase current, and the other one can be found as the two-phase current value. The third can be estimated by reconfiguring the three-phase current with one series shunt resistor on the dc bus side or two or three shunt resistors in series between the lower switches of the inverter 20 and ground. The fourth is the same as the third method, but it can be estimated by the method in which the shunt resistor is not inside the switch of the inverter 20 but inside. The three-phase current can also be detected by other methods, which is a general method used in the related art.

The current command converter 80 serves to convert the torque that is the output of the speed controller 70 into a current, and corresponds to the q-axis current command of the rotational coordinate system.

The vector current controller 90 is a three-phase / stationary coordinate system conversion unit 91 for converting the measured and estimated three-phase current to the stationary coordinate system, as shown in Figure 5, from the stationary coordinate system to the rotational coordinate system from the estimated position A static coordinate system / rotational coordinate system conversion unit 92, a current control unit 93 for generating a voltage in comparison with the d-axis, q-axis current and the command current of the rotary coordinate system, and a rotational coordinate system for converting the rotational coordinate system voltage to the stationary coordinate system. / Stop coordinate system 94, and a PWM generator 95 for generating a static coordinate system voltage as a three-phase voltage, which is a common method used in the prior art.

Hereinafter, an operation process and an effect of the start control method of the sensorless permanent magnet synchronous motor configured as described above will be described.

6 is a start control pattern diagram of a sensorless permanent magnet synchronous motor according to the present invention, wherein the vector current controller according to time when the permanent magnet synchronous motor 10 is switched to forced alignment, forced start, and sensorless driving is started. The d-axis and q-axis current command values of 90 are shown.

7 is a diagram illustrating a d-axis and q-axis current command value calculation algorithm when the sensorless permanent magnet synchronous motor of the present invention is started.

First, when the permanent magnet synchronous motor 10 is started without a sensor, forced alignment is very important. Therefore, as shown in FIG. 6, the permanent magnet synchronous motor 10 is forcedly aligned. When the d-axis current is directly applied, the axis of the permanent magnet synchronous motor 10 may be greatly shaken, thereby inclining the d-axis current command value. By gradually applying to minimize the shaking of the permanent magnet synchronous motor (10).

When forced alignment is performed, forced maneuvers are performed using the position and velocity information estimated by the second position velocity estimator 50 based on the mechanical model shown in FIG. 2, as shown in FIG. Slowly reduce the setpoint. When the d-axis current command value is directly applied to '0', when the load is large, the axis of the permanent magnet synchronous motor 10 moves and the position estimated by the second position speed estimator 50 by the mechanical model at the time of forced starting. This is because the actual position is not the same and the start fails.

Therefore, the d-axis current command value and the q-axis current command value can be smoothly started by applying the d-axis current command value through the original equation as shown in ① of FIG. Apply d-axis current setpoint by decreasing the slope as in ② of.

After starting the forced start, as shown in FIG. 6, a section of mixing the forced start and the sensorless drive and the switch to the sensorless drive is performed. In this case, the crossover function of FIG. 8 is used.

As can be seen in FIG. 8, the x-axis of the crossover function is position information estimated by the second position velocity estimator 50 by a mechanical model. In the conventional control of the sensorless permanent magnet synchronous motor 10, the speed command value is used for the x-axis of the crossover function. In this case, the speed and the speed command value estimated by the actual machine model may be different. May fail to maneuver.

Therefore, in the present invention, as shown in FIG. 8, the crossover function of the position velocity mixer 60 used when mixing the mechanical model and the electrical model is modified to estimate the x-axis of the crossover function by the mechanical model. If the location information is applied, the actual position at the time of forced start is the same as the estimated position, so that the failure to start by mixing using the crossover function can be minimized.

FIG. 9 is position information used for the estimated position and control at the start of the sensorless permanent magnet synchronous motor. FIG. 9 (a) shows the position information and the mixing section estimated by the machine model. b) displays the position information used for actual control by mixing the position information estimated by the machine model and the position information estimated by the electric model.

As can be seen from (c) of Figure 9, the position information estimated by the electrical model should be applied at a constant speed or more because the error is large at low speed.

FIG. 10 is a waveform diagram of a test experiment of the sensorless permanent magnet synchronous motor of the present invention, which increases the d-axis current by a predetermined slope during forced start to minimize the shaking of the shaft of the permanent magnet synchronous motor 10, and d during forced alignment. The axis current of the permanent magnet synchronous motor 10 does not move even if the load is large by applying the -axis current as a value obtained by the q-axis current and an arbitrary equation.

As described above, according to the start control method of the sensorless permanent magnet synchronous motor according to the present invention, when starting the permanent magnet synchronous motor without sensors in a system with large load fluctuations, minimizing start failure during forced start after forced alignment. The algorithm has been improved, and the crossover function that mixes the position and velocity information estimated by the mechanical model and the position and velocity information estimated by the electrical model can be modified to reduce the starting failure rate to a minimum.

What has been described above is only one embodiment for implementing the start control method of the sensorless permanent magnet synchronous motor according to the present invention, and the present invention is not limited to the above-described embodiment, but within the technical idea of the present invention. Of course, various modifications are possible by one of ordinary skill in the art.

Claims (6)

In a method of starting a permanent magnet synchronous motor through sensorless vector control, Forcibly aligning the permanent magnet synchronous motor by increasing the rotational coordinate system d-axis current command value of the vector control to a predetermined slope; And After forcibly aligning, the step of forcibly starting the permanent magnet synchronous motor by reducing the rotational coordinate system d-axis current command value of the vector control to a predetermined slope Starting control method of a sensorless permanent magnet synchronous motor, characterized in that it comprises. The method of claim 1, Controlling the x-axis of the crossover function based on the position information estimated by the machine model, which is a mixture of the position and velocity information estimated by the machine model and the position and velocity information estimated by the electric model after the forced start is started. To Starting control method for a sensorless permanent magnet synchronous motor further comprising. In a method of starting a permanent magnet synchronous motor through sensorless vector control, And a d-axis current command value of the rotational coordinate system of the vector control is increased by a predetermined slope during forced alignment of the permanent magnet synchronous motor. In a method of starting a permanent magnet synchronous motor through sensorless vector control, And the d-axis current command value of the rotational coordinate system of vector control is reduced and applied to a predetermined slope when the permanent magnet synchronous motor is forcibly started. The method of claim 4, wherein When the permanent magnet synchronous motor is forcibly started, the d-axis current command value is applied according to an arbitrary equation of the rotational coordinate system d-axis current and q-axis current of the vector control. . In a method of starting a permanent magnet synchronous motor through sensorless vector control, After the forced start of the permanent magnet synchronous motor starts, the x-axis of the crossover function that mixes the position and velocity information estimated by the mechanical model with the position and velocity information estimated by the electrical model is estimated by the mechanical model. Starting control method for a sensorless permanent magnet synchronous motor, characterized in that the control based on the information.

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