CN100486103C - Control device and method for motor speed - Google Patents

Abstract

A speed control device and method for a motor. The speed control device for a motor includes dividing the interval within one revolution of a rotor into several intervals, calculating the speed in several intervals, and calculating the speed from the estimated speed in several intervals. The average speed, and compare the average speed with the speed in each interval to obtain the speed estimation device of the speed fluctuation; the speed fluctuation of each interval output by the speed estimation device is passed through the speed controller with proportional and integral functions, and then A speed fluctuation compensation device that outputs the speed fluctuation value; compares the average speed output by the speed estimation device with the speed command value, and according to the comparison, a torque current command value generating device that outputs a torque current command value; The torque current command value is compared with the speed fluctuation compensation value and the actual torque current value, and the comparison device generates the final torque current value according to the comparison result.

Description

Motor speed control device and method

technical field

The invention relates to a speed control device and method of a motor.

Background technique

Generally, compressors have different load characteristics depending on the compression method. Especially in the case of Single Rotary Compressor, the torque fluctuation is very large when the machine rotates one revolution, and the speed fluctuation is also very large when a general speed controller is used.

As shown in Figure 1, the existing compressor is connected to the rotating shaft of the motor, and the center of the rolling ring and the center of the motor shaft are not on a straight line.

As shown in Figure 2, when the motor is working, the rolling ring also works at the same time, and when the rolling ring mechanically rotates one revolution, the compression work is also performed once, but as shown in Figure 3, a large torque fluctuation occurs on the load of the motor .

The 'θ' angle in Figure 3 is the mechanical rotation angle, and the relationship between the rotation angle and the load fluctuation is related to the position of the motor rotation shaft when it is connected to the compressor.

As shown in Figure 4, the compressor is under high temperature and high pressure when it works, so it is impossible to use the sensor. In the case of variable frequency compressors, it is necessary not to use sensor control. Depending on the motor used, the speed control device may have different local structures, but generally it includes a speed controller as shown in Figure 4, and a current controller is installed inside. , to detect voltage or current when speed calculation is required.

The speed control device shown in Fig. 4 has a large load characteristic as in Fig. 3(a), and produces speed fluctuations as in Fig. 3(b). Therefore, vibration and noise are generated when the speed is controlled, and there is also a problem of performance degradation.

In order to solve the above problems, in the prior art, the torque compensation method shown in Figure 5 is used to obtain the load characteristics in advance, and a look-up table (LOOKUP TABLE) corresponding to this characteristic is made.

In this way, the existing torque compensation method is generally used on the BLDC motor of the 120-degree zero-cross detection energization method. In the case of the 120-degree zero-cross detection energization method, according to the characteristics of the torque compensation method, only at 60-degree intervals It can only be detected, so one cycle can only be compensated 6 times.

However, when the look-up table (LOOKUP TABLE) shown in Figure 5 is used, the compensation can only be performed at the specified position, so the reference position needs to be specified, and the error of the reference position will have a negative impact on the entire torque compensation.

In order to solve the above problems, the sine wave sensorless control method is used to calculate the average value to compensate for the speed fluctuation. However, the method of compensating speed fluctuations using the above average value cannot calculate local accurate speed compensation. As shown in Figure 6, although the overall speed control is very good, local speed fluctuations cause vibrations.

When the speed estimation value is 22HZ, the mechanical rotation is one cycle, and the overall speed is maintained at 22HZ, but the local speed fluctuations are very large within one cycle.

When a 4-pole motor is used, one mechanical rotation is equal to two electronic rotations. At this time, it is necessary to know the local speed fluctuation to perform better speed compensation.

Contents of the invention

In order to overcome the above-mentioned shortcomings of existing compressor torque compensation methods, the present invention provides a motor speed control device and method, which divides the interval within one rotation of the rotor into several intervals, and calculates the speed in several intervals. The average speed is obtained from the estimated speed in several intervals, and the above average speed is compared with the speed in each interval, and the speed fluctuation is compensated according to the comparison result.

The speed control device of motor of the present invention is:

A speed control device for a motor, characterized in that it includes dividing the interval within one rotation of the rotor into several intervals, calculating the time for increasing the angle in each interval to calculate the speed of each interval, and calculating the speed in several intervals Calculate the average speed from the speed, and compare the average speed with the speed in each interval to obtain the speed estimation device for the speed fluctuation; the speed fluctuation of each interval output by the speed estimation device is passed through the speed with proportional and integral functions. The controller, and then the speed fluctuation compensation device that outputs the speed fluctuation value; compares the average speed output by the speed calculation device with the speed command value, and according to the comparison, the torque current command value generating device that outputs the torque current command value ; Comparing the torque current command value with the speed fluctuation compensation value and the actual torque current value, and generating the final torque current value according to the comparison device.

In the aforementioned speed control device for a motor, the speed estimation device calculates the time for increasing the angle in each section to calculate the speed in each section.

In the aforementioned motor speed control device, the speed fluctuation compensation device passes the difference between the average speed and the speed of each section through the speed controller with proportional and integral functions, minimizes the passed value, and then outputs the speed fluctuation compensation value.

The speed control method of motor of the present invention is:

A speed control method for a motor, characterized in that it includes: calculating the time for increasing the angle in each interval to calculate the speed of each interval, and using the speed of each interval to obtain an average speed; The process of comparing the speed to calculate the speed compensation value; comparing the above average value with the speed command value to calculate the process of torque current command value; comparing the above speed fluctuation compensation value with the torque current command value and the actual torque current Values are compared, the final torque current value is calculated, and the final torque current value is used to compensate the load.

In the speed control method of the aforementioned motor, the speed of each section is calculated, and the process of using the speed of each section to obtain the average speed includes calculating the time for the angle increase of each section.

The speed control method of the aforementioned motor, wherein the process of comparing the above-mentioned average speed with the speed of each interval, and calculating the speed compensation value includes: passing the difference between the average speed and the speed of each interval through the speed controller process with proportional and integral functions and It is the process of minimizing the passed value and then outputting the speed fluctuation compensation value.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a schematic structural diagram of an existing compressor.

Fig. 2 is a schematic diagram of the operation of the compressor shown in Fig. 1 .

Fig. 3 is a graph showing the load characteristics of the compressor shown in Fig. 1 .

Fig. 4 is a block diagram of an existing motor speed control device.

Fig. 5 is a schematic diagram of an existing torque compensation method.

Fig. 6 is a schematic diagram of an existing speed error embodiment.

Fig. 7a is a speed fluctuation diagram of the present invention which calculates the speed and the average speed in each interval and detects the speed in each interval.

Fig. 7b is a diagram of fluctuations in speed within one revolution of the machine when the present invention is under load.

Fig. 7c is a schematic diagram of an embodiment of the present invention adopting a 4-pole motor to set the initial angle as '0 degree, 180 degree, 360 degree.

Fig. 8 is a block diagram of an embodiment of the speed control device of the motor of the present invention.

Fig. 9 is a working flowchart of another embodiment of the speed control device of the motor of the present invention.

Explanation of symbols in the figure:

100. Speed calculator 200. Speed fluctuation compensation department

300 Torque current command value generation part 400. Comparator

Detailed ways

As shown in Fig. 7a, the present invention can detect the speed fluctuation in each interval by calculating the speed and the average speed in each interval, and can compensate the speed fluctuation in each interval.

As shown in Figure 7b, when there is a load, there is a fluctuation in speed within one revolution of the mechanical type. When calculating the position, the increase rate of the angle increase in each interval is different, and the interval is divided into equal parts according to a specific angle, and then Calculate the time for the angle increase of each interval to calculate the speed of each interval.

As shown in Fig. 7c, it is an embodiment in which a 4-pole motor is used to set the initial angle as '0 degree, 180 degree, 360 degree'. There are 4 intervals produced in one cycle of the mechanical type, and the speed fluctuation in each interval is calculated by subtracting the speed corresponding to each interval and the average value obtained in the entire interval, so speed compensation can be carried out according to the present invention, as shown in Fig. 8 and Figure 9 in detail.

As shown in Figure 8, on the basis of the module shown in Figure 4, the present invention divides the interval within one revolution of the rotor into several intervals, calculates the speed in several intervals, and calculates the speed in several intervals Find the average speed in the above-mentioned average speed and the speed in each interval are compared to obtain the speed calculator (100) of the speed fluctuation; And the speed controller of the integral function, then the speed fluctuation compensator (200) that the speed fluctuation value is output; the average speed output in the above-mentioned speed calculator (100) is compared with the speed command value, and according to the comparison, the output torque current Torque current command value generation part (300) of the command value; compare the torque current command value with the speed fluctuation compensation value and the actual torque current value, and generate the comparator (400) of the final torque current value according to the comparison result .

The process of the speed compensation operation of the present invention will be described below.

First, the speed estimator (100) estimates the speed in several intervals, calculates the average speed among the estimated speeds in the several intervals, and then calculates the difference between the average speed and the speed of each interval to obtain the speed fluctuation.

The speed calculator (100) determines the number of sections according to the number of poles of the motor, and calculates the time for increasing the angle in each section to calculate the speed of each section.

The speed fluctuation compensator (200) outputs the speed fluctuation compensation value for each interval outputted by the speed calculator (100) through a speed controller having proportional and integral functions.

That is, the speed fluctuation compensation part (200) passes the difference between the average speed and the speed of each section through the speed controller with proportional and integral functions, so as to minimize the passing value, and then output the speed fluctuation compensation value.

In addition, the torque current command value generator (300) compares the average speed output by the above-mentioned speed estimator (100) with the speed command value, and inputs the torque current command value to the comparator (400) according to the comparison result, Next, the comparator (400) adds the above-mentioned torque current command value, speed fluctuation compensation value and actual torque current value, and inputs the calculated final torque current command value to the current controller (not shown) for Compensation load.

As shown in Figure 9, first calculate the speed of each section (SP1), then use the speed of each section to calculate the average speed (SP2), and then calculate the time for each section to increase the angle.

Then compare the above average value with the speed of each section, and calculate and calculate the speed fluctuation compensation value (SP3) according to the comparison result. Then, the difference between the average speed and the speed of each section passes through the speed controller with proportional and integral functions. The value becomes the minimum value, and then output the speed fluctuation compensation value.

The next step is to compare the above average speed with the speed command value, calculate the torque current command value (SP4) according to the comparison result, and then calculate the above torque current command value, speed fluctuation compensation value and actual torque current value. Addition calculation, according to the calculated final torque current command value (SP5) input to the current controller to compensate the load (SP6).

The speed control device and method of the motor of the present invention is to divide the interval within one revolution of the rotor into several intervals, estimate the speed in several intervals, and calculate the average speed in the estimated speed in several intervals, and obtain the above-mentioned The difference between the average speed and the speed in each section, and the speed fluctuation is compensated according to the speed difference.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still belong to within the scope of the technical solutions of the present invention. ,

The present invention has following effect:

The present invention divides the interval within one revolution of the rotor into several intervals, calculates the speed in several intervals, and calculates the average speed from the estimated speeds in several intervals, and compares the average speed with the speed in each interval, The speed fluctuation is compensated according to the comparison result, so that the speed fluctuation can be avoided and the control speed can be improved.

Claims (6)

1, a kind of speed control unit of motor, it is characterized in that, comprise that the interval that rotor was rotated a circle in the phase is divided between several region, the time that calculates each interval interior increase angle is calculated each overall travel speed, and obtain average speed in the reckoning speed between several region, and this average speed and each interval interior speed are compared the speed calculation device of obtaining velocity perturbation;

Each overall travel speed fluctuation of exporting in this speed calculation device, by having the speed control of ratio and integrating function, the velocity perturbation compensation arrangement that the velocity perturbation value is exported again;

Average speed and the speed value exported in this speed calculation device are compared,, export the torque current command value generation device of torque current command value according to relatively;

Compare at this torque current command value and velocity perturbation offset and actual torque current value, produce the comparison means of final torque current value according to comparative result.

2, the speed control unit of motor according to claim 1 is characterized in that,

Above-mentioned speed calculation device calculates each time that increases angle in interval and calculates each overall travel speed.

3, the speed control unit of motor according to claim 1 is characterized in that,

Above-mentioned velocity perturbation compensation arrangement by having the speed control of ratio and integrating function, becomes the difference of average speed and each overall travel speed to the value of passing through and minimizes, again output speed oscillation compensation value.

4, a kind of method for control speed of motor is characterized in that, comprising:

The time that calculates each interval interior increase angle is calculated each overall travel speed, and utilizes each interval speed to obtain the process of average speed;

Above-mentioned average speed and each overall travel speed are compared, calculate the process of velocity compensated value;

Above-mentioned mean value and speed value are compared, calculate the process of torque current command value;

Above-mentioned velocity perturbation offset and torque current command value and actual torque current value are compared, calculate final torque current value, again with the process of final torque current value compensation load.

5, the method for control speed of motor according to claim 4 is characterized in that,

Each interval speed of aforementioned calculation comprises in the process of utilizing each interval speed to obtain average speed, calculates the time that each interval angle increases.

6, the method for control speed of motor according to claim 4 is characterized in that,

Above-mentioned average speed and each overall travel speed are compared, and the process that calculates velocity compensated value comprises,

The speed control process and the value passed through become of the difference of average speed and each overall travel speed by having ratio and integrating function minimized, again the process of output speed oscillation compensation value.

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