KR20060105128A - Method for controlling torque drive of motor - Google Patents

Abstract

When the motor is driven at high speed or driven for a long time and switched to low speed torque drive, the drive is stably performed at low speed.

The microcomputer detects the current generated from the motor and the rotational speed of the motor while driving the motor according to the speed command after the initial start of the motor, and starts the motor when a speed change command is generated to drive the motor at a low speed torque drive. The motor is driven at an initial starting speed, and when the motor is stably driven at an initial starting speed, the motor is driven at a low speed torque drive for a set time according to the speed change command, and when the set time elapses, When the speed error is detected and the detected speed error is more than the preset limit value, the motor is stopped, and when the detected speed error is less than the preset limit value, the motor is continuously driven by a low speed torque drive according to the speed change command. Low speed torque drive restricts sudden entry and stabilizes low speed earth Reduces vibration and noise by driving large.

Motor, compressor, torque drive, low speed drive, speed error,

Description

Method for controlling torque drive of motor

1 is a longitudinal sectional view showing a configuration of a general single rotary compressor.

1B is an enlarged sectional view taken along the line A-A of FIG.

2a and 2b is a graph showing the relationship between the change in the rotational angular velocity according to one rotation of the motor, the torque and the load torque of the motor in a single rotary compressor.

Figure 3 is a block diagram showing the configuration of a motor drive device to which the torque drive control method of the present invention is applied.

4 is a functional block diagram of the microcomputer of FIG.

5 is a signal flow diagram showing a torque drive control method of the present invention.

The present invention relates to a torque drive control method of a motor that controls torque drive of a motor according to a change in load. Particularly, in a single rotary compressor, the motor switches to a low speed torque drive depending on the surrounding conditions during high speed driving or long time driving. The present invention relates to a torque drive control method of a motor capable of stably driving at low speed in the event of a failure.

BACKGROUND ART Refrigeration and cooling compressors, which are widely used in refrigerators and air conditioners, generally perform a suction stroke for sucking refrigerant gas evaporated from an evaporator, and a discharge stroke for discharging the suction refrigerant gas by raising the pressure to the saturation pressure of the condenser. .

The compressor is roughly divided into a volumetric compressor and a centrifugal compressor, and the volumetric compressor is divided into an open compressor and a hermetic compressor according to the external structure, and the hermetic compressor is classified into a semi-hermetic compressor and a hermetic compressor. do.

The volumetric compressor compresses the volume of the refrigerant gas sucked in to increase the pressure of the refrigerant gas, and the centrifugal compressor increases the pressure of the refrigerant gas at a high speed by a rotating impeller and increases the refrigerant gas at the outlet of the impeller. Kinetic energy is transformed into pressure in the diffuser.

In such a compressor, conventionally, a low-speed horizontal reciprocating compressor is mainly used, but a light-weight compressor that operates gradually at a smaller size and a higher speed has been developed and used, and a single rotary compressor called a one-rotation type in a small refrigeration and cooling device. And scroll compressors are used. In particular, the single rotary compressor is very advantageous in terms of manufacturing cost compared to performance, and is widely used for compressing refrigerant gas in small capacity and high speed air conditioners.

1A is a longitudinal sectional view showing the configuration of a general single rotary compressor, and FIG. 1B is an enlarged sectional view taken along the line A-A of FIG. 1A. Here, reference numeral 100 denotes a compressor body. The compressor main body 100 is separated into a motor unit 110 and a compression unit 120. The stator 111 and the rotor 113 are installed in the motor unit 110, and the driving shaft 117 is connected to the rotating shaft of the rotor 113 via a bearing 115.

The compression unit 120 is formed with a suction port 123 for sucking the refrigerant gas and a discharge port 125 for discharging the compressed refrigerant on the wall surface of the cylinder 121, between the suction port 123 and the discharge port 125. In addition to the rolling pin 127, a spring 127a for allowing the rolling pin 127 to be touched to the inside of the cylinder 121 is installed at the rear of the rolling pin 127.

An inner side of the cylinder 121 is provided with a vane 129 which is an eccentric cam, and an end of the driving shaft 113 of the motor 111 is fixed to the vane 129.

In the single rotary compressor having such a configuration, when power is supplied to the motor 111, the rotor 113 of the motor 111 rotates, and the drive shaft 117 rotates according to the rotation of the rotor 113, thereby compressing the compression unit. The vane 129 of 120 is rotated.

Then, the compression unit 120 is the refrigerant gas is sucked into the suction port 123 in accordance with the rotation of the vane 129, the sucked refrigerant gas is compressed by the rotation of the vane 129 is discharged to the discharge port 125, At this time, as the vane 129 rotates, the rolling pin 127 floats inwardly of the cylinder 121 by the elastic force of the spring 127a, and comes into contact with the outer circumferential surface of the vane 129, and the suction port 123 and the discharge port ( Since the 125 is separated from each other, the refrigerant gas sucked into the suction port 123 is not discharged directly to the discharge port 125, and the compressed refrigerant gas is not mixed with the refrigerant gas sucked into the suction port 123.

In the single rotary compressor, a compression stroke that reduces the volume of refrigerant gas and a discharge stroke where the volume of the refrigerant gas is restored to its original state are generated every time the motor is mechanically rotated. The required load torque will be different.

That is, the stroke cycle of a single rotary compressor is divided into a suction / compression stroke and a discharge stroke. The suction / compression stroke and the discharge stroke are repeated every time the drive shaft 117 of the motor 111 rotates by one rotation. The load torque gradually increases during the suction / compression stroke, and the discharge stroke is gradually increased. Since the load torque is rapidly decreased during the execution, the load torque of the compressor is changed during one cycle of driving of the motor 111.

2A and 2B are graphs showing the relationship between the rotational angular velocity and the torque of the motor 111 of the compressor. As shown in FIG. 2B, due to the residual torque, which is a difference between the output torque of the motor 111 and the load torque required by the compressor to compress the refrigerant gas, Fluctuations occur, and such fluctuations in the rotational angular velocity cause vibration of the compressor to generate noise, and the generated vibration may cause breakage of the pipes connected to the inlet 123 and the discharge port 125 of the compressor. .

As such, the single rotary compressor has a considerable difficulty in low speed operation because the torque ripple of the load shows a very large deviation in a mechanical cycle due to the characteristics of the compression method.

Therefore, in the related art, various torque ripple compensation methods for driving the motor 111 of a single rotary compressor are proposed to compensate for the torque ripple as described above and operate at a high speed, but the motor 111 operates at high speed. Alternatively, when switching to a low speed torque drive according to the surrounding conditions while operating for a long time, a large amount of torque ripple still occurs due to the overload of the single rotary compressor, which causes a considerable amount of vibration and noise. In addition, the generated vibration may cause damage not only to the compressor but also to peripheral devices, such as shortening the service life of the compressor and other devices located around the compressor.

Therefore, an object of the present invention is to detect the current generated from the motor when driving the motor, and to detect the rotational speed of the motor, and when the motor is switched to a low speed torque drive in the state of driving the motor at high speed or for a long time. The present invention provides a method of controlling the torque drive of a motor by limiting sudden entry to low speed torque drive by using the detected ripple of the current and the rotational speed of the motor and ensuring stable low speed torque drive.

The torque drive control method of the motor of the present invention having the above object detects the current generated from the motor and the rotational speed of the motor while driving the motor according to the speed command after the microcomputer initially starts the motor. When the speed change command for driving by torque drive is generated, the motor is driven at the initial starting speed, and when the motor is stably driven at the initial starting speed, the motor is operated at low speed for a predetermined time according to the speed change command. The motor is driven by driving, and when the speed error of the motor is detected when the set time has elapsed, the motor is stopped when the detected speed error is greater than or equal to a preset limit value, and when the detected speed error is less than a preset limit value, It drives the motor at low speed torque drive according to the speed change command. do.

The determination of whether the motor is stably driven at the initial starting speed detects the ripple of the rotational speed of the motor and the magnitude of the current generated in the motor, and stably stabilizes the initial starting speed when the magnitude of the speed ripple and the current is less than a preset limit value. It is determined that the motor is driven, and the speed error detection of the motor starts when the motor is started at the initial starting speed and is detected when a predetermined time has elapsed, and after stopping the motor, It is characterized by driving again from the initial startup.

Hereinafter, the torque drive control method of the motor of the present invention will be described in detail with reference to the accompanying drawings of FIGS. 3 to 5.

Figure 3 is a block diagram showing the configuration of a motor drive device to which the torque drive control method of the present invention is applied. Here, reference numeral 300 denotes an AC voltage, and reference numeral 310 denotes a rectifier for rectifying the AC voltage 300 to generate a DC voltage.

Reference numeral 320 is an inverter for generating a three-phase driving current by switching the output voltage of the rectifier 310 according to the phase driving signals Va +, Va- (Vb +, Vb-) (Vc +, Vc-). The inverter 320 is a motor that is a driving source of a single rotary compressor driven according to the three-phase driving current output.

Reference numeral 340 is a microcomputer. The microcomputer 340 drives the driving state of the motor 330 by using the currents Ia, Ib, and Ic generated by the motor 330 and the output voltage of the rectifier 310 as the motor 330 is driven. While determining, phase driving signals Va + and Va− (Vb + and Vb−) (Vc + and Vc−) are generated and output to the inverter 320.

4 is an internal functional block diagram of the microcomputer 340. As shown in this figure, the inverter 320 generates a feedback signal by detecting the rotor position and the rotational speed of the motor 330 with the current generated from the motor 330 as the motor 330 is driven. And a subtractor 404 for calculating an error value by subtracting the feedback signal of the position / speed feedback unit 400 from the speed command unit 400 and the speed command generated by the speed command generation unit 402, and the subtractor. Torque of the motor 330 when the speed controller 406 generates a speed control signal according to the output signal of 404 and the speed controller 406 generates a speed control signal for driving the motor 330 at low speed. A torque control unit 408 for controlling driving, and a high speed control unit 410 for controlling the high speed driving of the motor 330 when the speed controller 406 generates a speed control signal for driving the motor 330 at high speed; The output of the torque controller 408 and the high speed controller 410 A current command calculation unit 412 for generating a current command to drive the motor 330 according to the call; a current control unit 414 for converting the current command generated by the current command calculation unit 412 into a voltage command; The current controller 414 generates a pulse width modulation (PWM) signal according to the generated voltage command and outputs the phase driving signals Va + and Va- (Vb + and Vb-) (Vc + and Vc-) to the inverter 320. It was composed of a voltage control unit 416.

In the motor driving apparatus having such a configuration, the rectifier 310 rectifies and smoothes the input AC voltage 300 to generate a DC voltage, and the generated DC voltage is supplied to the inverter 320 as the driving voltage of the motor 330. .

In addition, the microcomputer 340 generates a speed command for the speed command generator 402 to drive the motor 330, and the generated speed command is input to the speed controller 406 through the subtractor 404 to speed controller 406. ) Generates a speed control signal for driving the motor 330.

When the speed control signal generated by the speed controller 406 is a speed control signal for driving the motor 330 at a low speed, the torque control unit 408 drives to drive the motor 330 at low speed according to the speed control signal. Signal is generated, and when the speed control signal generated by the speed controller 406 is a speed control signal for driving the motor 330 at high speed, the high speed controller 408 drives the motor 330 at high speed according to the speed control signal. A driving signal for driving is generated, and the generated driving signal is inputted to the current command calculator 412 and converted into a current value for driving the motor 330.

The current value output from the current command calculator 412 is converted into a voltage for driving the motor 330 in the current controller 414, and the voltage controller 416 converts the converted voltage level into a PWM signal. The phase driving signals Va + and Va- are output as Vb + and Vb- (Vc + and Vc-).

Phase driving signals Va + and Va− (Vb + and Vb−) Vc + and Vc− output by the voltage controller 416 are input to the inverter 320, and the inverter 320 is the phase driving signal Va +. And a plurality of switching elements are selectively operated according to Va-) (Vb +, Vb-) (Vc +, Vc-), switching the output voltage of the rectifier 310 to generate a three-phase driving current, and generating a three-phase driving. Current is supplied to the motor 330 to drive the motor 330.

When the motor 330 is driven as described above, currents Ia, Ib and Ic are generated in each phase of the motor 330, and the generated phase currents Ia, Ib and Ic are fed back to the microcomputer 340 as a microcomputer. The position / speed feedback unit 400 of the computer 340 detects the position and rotation speed of the rotor of the motor 330 with the phase currents Ia, Ib, and Ic to generate a feedback signal.

The feedback signal generated is input to the subtractor 404, and the subtractor 404 calculates a speed error value by subtracting the feedback signal of the position / speed feedback unit 400 from the output signal of the speed command generator 402. The motor 330 is driven according to the calculated speed error value so that the motor 330 is rotated at a speed according to the output signal of the speed command generator 402.

Figure 5 is a signal flow diagram showing a torque drive control method of the present invention applied to the motor drive device as described above. As shown in FIG. 500, the microcomputer 340 drives the motor 330 at an initial starting speed by performing an initial starting routine in step 500.

When the motor 330 is driven at the initial starting speed, step 504 while driving the motor 330 at high speed according to the speed command generated by the speed command generation unit 402 according to temperature and humidity in step 502. ) Detects the current (Ia, Ib, Ic) generated by the driving of the motor 330 and the rotational speed of the motor 330.

In the next step 506, the microcomputer 340 determines whether a speed change command for changing the rotational speed of the motor 330 is generated, and returns to step 502 if no speed change command is issued. The motor 330 is continuously driven at a high speed at a speed according to the currently generated speed command.

When the speed change command is generated as a result of the determination in step 506, the microcomputer 340 determines whether the speed change command generated in step 508 is a speed change command for driving the motor 330 at low speed. If it is determined that it is not a speed change command for low speed torque drive, the motor 330 is driven at a high speed according to the speed command changed in step 502.

In the case where the determination result of the step 508 is a speed change command for low speed torque driving, the microcomputer 340 drives the motor 330 at the initial starting speed in step 510. That is, it drives at the initial starting speed for driving the motor 300 in the initial starting routine.

In the next step 512, it is determined whether the motor 300 has been driven at the initial starting speed for a predetermined time, and the motor 300 continues to be driven at the initial starting speed for a predetermined time. When a predetermined time elapses, in step 514, the speed ripple of the motor 330 and the magnitude of the current are detected. That is, the magnitude of the synthesized current calculated by combining the amount of change in the rotational speed of the motor 330 and the currents (Ia, Ib, Ic) generated by the driving of the motor 330 is calculated.

In the next step 516, it is determined whether the magnitudes of the calculated speed ripple and the current are all less than the preset limit value, and if the magnitudes of the speed ripple and the current are not less than the preset limit value, the step 510 is performed. Returning to, the motor 300 is continuously driven at an initial starting speed, and the operation of detecting whether the speed ripple and the current are less than the predetermined limit value is repeatedly performed.

If the detected speed ripple and the magnitude of the current in the step 516 are less than a preset limit value, the microcomputer 340 drives the motor 330 at a low speed at the changed speed in step 518, that is, The motor 330 is torque driven at a low speed according to the speed change command.

In the next step 520, after the motor 330 is torque driven, it is determined whether a predetermined time has elapsed, and when the set time has not elapsed, the motor 330 continues to drive the torque according to the speed change command. When the set time has elapsed, a speed error is calculated by comparing the rotation speed of the motor 330 currently set with the actual rotation speed of the motor 330 in step 522.

In the next step 524, it is determined whether the calculated speed error is less than the preset limit value, and if it is not less than the limit value, the microcomputer 340 generates an error in the low speed torque drive of the motor 330. In step 526, the motor 330 is stopped, and when the time set in step 528 has elapsed, the process returns to step 500 and repeated from the initial starting routine.

When the speed error is less than the limit as a result of the determination in step 524, the microcomputer 340 determines that the motor 300 is normally at low speed, and the speed of the low speed torque drive is determined at step 530. The furnace 330 continues to drive and ends.

On the other hand, while the present invention has been shown and described with respect to specific preferred embodiments, various modifications and changes of the present invention without departing from the spirit or field of the invention provided by the claims below It can be easily understood by those skilled in the art.

As described above, the present invention restricts sudden entry to low speed torque drive by using the current generated in the motor and the rotational speed of the motor when the motor needs to be driven at a low speed while driving the motor at high speed or for a long time. In addition, by stably operating low speed torque, vibration and noise that can occur during low speed torque driving can be reduced, as well as the damage of the compressor and surrounding components can be prevented by the generated vibration. .

Claims (4)

The microcomputer rotating the motor at an initial starting speed and rotating the motor at a high speed according to a speed change command; Determining whether the motor rotates at the initial starting speed and stably rotates the motor at the initial starting speed when a speed change command for driving at low speed torque drive is generated while the motor is rotating at high speed; Driving the motor for a predetermined time with a low speed torque drive according to the speed change command when the motor is rotated at an initial starting speed; Detecting a speed error of a motor rotating at the low speed torque drive; Stopping the motor when the detected speed error is equal to or greater than a preset limit value; And And driving the motor at a low speed torque drive in accordance with a speed change command when the detected speed error is less than a preset limit value. The method of claim 1, wherein the determination of whether the motor rotates stably at the initial starting speed; As the motor rotates, the magnitude of current generated by the motor, the ripple of the rotational speed is detected, and when the magnitude of the detected current and the ripple of the rotational speed are less than a preset limit value, the motor rotates stably at the initial starting speed. Torque drive control method for a motor, characterized in that judged to be. The method of claim 1, wherein the speed error detection of the motor; A method for controlling torque drive of a motor, characterized in that the motor is started at an initial starting speed and detected when a predetermined time elapses. 2. The method of claim 1, further comprising: after stopping the motor; And driving the motor again from an initial startup after a predetermined time has elapsed.

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