JPH0217884A - Control device of motor for compressor - Google Patents

Abstract

PURPOSE:To reduce the occurrence of oscillation by varying the voltage in one rotation in accordance with the load fluctuation pattern imposed onto an output shaft. CONSTITUTION:An output shaft 3 of a motor 1 is directly coupled to a compressor 2. This motor 1 is connected to a power source 5 through a converter 4. The converter 4 varies the voltage supplied to the motor 1 in synchronization with the rotation of the motor 1. In this way, the speed change in one rotation of the output shaft can be so well controlled that the occurrence of oscillation can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a compressor motor that drives a compressor in which the load applied to the output shaft changes in the same pattern during one rotation.

The electric motor that drives the compressor, which repeats the cycles of suction, compression, and discharge during one concave rotation, has a load applied to the output shaft during one revolution that fluctuates in a path pattern as shown in Figure 1 (C). . On the other hand, conventional t! iI! The voltage and current pattern supplied to the 1 machine has a waveform as shown in Figure 1 (A) so that 4-torque is output during one rotation, and a rotating magnetic field as shown in Figure 1 (B) is obtained. It is something.

However, when the load torque is applied as shown in FIG. 2(C), a speed change as shown in FIG. 2(D) occurs during one rotation.

In other words, during the compression stroke, when a large load torque is applied to the output shaft of the motor, the rotational speed decreases, and when the load torque applied to the output shaft is small, such as during the suction stroke, the rotational speed increases, resulting in a large speed difference during one rotation. occurs. It was discovered that this speed change is the cause of vibration.

This invention was made with attention to the above circumstances, and its purpose is to reduce the occurrence of vibration by varying the voltage during one rotation according to changes in the load applied to the output shaft and arm turns. The present invention provides a control device for a compressor motor that can perform the following steps.

The present invention will be described below based on an embodiment shown in the drawings. Reference numeral 1 in FIG. 2 is an electric motor that drives the compressor 2, and this output shaft 3 is directly connected to the compressor 2. This electric motor 1 is connected to a power source 5 via a converter 4, and this converter 4 can vary the voltage supplied to the electric motor 1 in synchronization with the rotation of the electric motor 1. That is, in the case of a load pattern in which the load torque applied during one rotation of the output shaft 3 of the electric motor 1 that drives the compressor 2 gradually increases from oo to 3600 as shown in FIG. As shown in FIG. 3B, the converter 4 is controlled in synchronization with the rotation of the output shaft 3 of the electric motor 1, and converts the current into a current according to the load pattern.

Therefore, a current commensurate with the load torque applied to the output shaft 3 is supplied, and the strength of the magnetic field corresponding to the load as shown in FIG. 3(C) is obtained. Therefore, speed changes during one rotation of the output shaft 3 of the electric motor 1 can be suppressed. Therefore, it is possible to substantially eliminate vibrations due to speed changes.

As explained above, the present invention is a control device for a motor in which the load applied to the output shaft changes in the same pattern during one rotation, and in which a voltage is changed between the motor and the power source according to the pattern in which the load changes. Since the output shaft is provided with an electric current, it is possible to supply a current commensurate with the load torque, suppress speed changes during one rotation of the output shaft, and reduce the occurrence of vibration.

[Brief explanation of the drawing]

Figures 1 (A) to (D) are explanatory diagrams of the conventional technology, where (A) is a current waveform diagram, (B) is an explanatory diagram showing the strength of the magnetic field, and (C) is a curve diagram showing changes in load torque. , (D) is a curve diagram showing changes in rotational speed, FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 3 (A) is a curve diagram of load torque, and FIG.
) is a current waveform diagram of the present invention, and (C) of the same figure is an explanatory diagram similarly showing the strength of the magnetic field. 1... Electric motor, 2... Compressor, 3... Output shaft, 4
...Converter, 5...Power supply. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 (B) Figure 3 0'-1 □360''

Claims (1)

[Claims] In a control device for a compressor motor, in which the output shaft is directly connected to a compressor that repeats suction, compression, and discharge cycles during one rotation, and the load applied to the output shaft fluctuates in the same pattern during one rotation, A control device for a compressor motor, characterized in that a converter is provided between a power source of the motor and a converter that varies a voltage applied during rotation of the motor according to a variation pattern of a load applied to the output shaft.