JP2008259348A - Motor control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the efficiency of an auxiliary coil and a control device by stopping the electricity application of the auxiliary coil depending on an operation state, in the variable control of a single-phase induction electric motor. <P>SOLUTION: The motor control device is provided with a signal correction means 9 which determines the operation state from a frequency command FC and a main coil current IR, and according to the result of the determination, selects whether to output control signals Pc and Pd as Pc2 and Pd2 as they are, or to output the Pc2 and Pd2 set in the off-state irrespective of the control signals Pc and Pd. Electricity application to the auxiliary coil is stopped by the signal correction means 9 while keeping the control signals Pc2 and Pd2 in the off-state depending on the operation state, and thereby the efficiency of the motor control device can be improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a motor control device that drives a single-phase induction motor at a variable speed.

Conventionally, as this type of motor control device, for example, by controlling switching of a three-phase inverter circuit connected to a single-phase induction motor and applying a phase-shifted voltage to each winding of the motor, Some control the direction and the rotational speed (see, for example, Patent Document 1).
JP 7-46872 A

  However, if the current to the auxiliary coil is always turned on after the start as in the prior art, for example, the torque generated by the main coil is low when the generated torque is larger than the load torque, or the torque generated by the main coil, for example. During high-speed operation in which the influence of the pulsation of the motor on the speed fluctuation and vibration is small, loss due to energization of the auxiliary coil and switching of the inverter circuit reduces the efficiency of the motor control device.

  An object of the present invention is to solve the above-described problems of the prior art, and to provide an efficient motor control device.

  In order to solve the above-mentioned conventional problems, the motor control device of the present invention is provided with signal correction means for turning on or off the voltage application to the auxiliary coil depending on the operating state of the single-phase electric induction machine.

  According to the present invention, it is possible to provide an efficient motor control device by turning off the voltage application to the auxiliary coil when unnecessary.

  According to the first aspect of the present invention, the voltage application to the auxiliary coil is turned off except at the time of starting, and loss due to energization to the auxiliary coil and switching of the inverter can be reduced without being reversed at the time of starting.

  According to the second aspect of the present invention, the voltage application to the auxiliary coil is turned off when the load is low, and loss due to energization of the auxiliary coil and switching of the inverter can be reduced without impairing the operating range when the load is high.

  According to the third aspect of the present invention, voltage application to the auxiliary coil is turned off during high-speed operation, and loss due to energization to the auxiliary coil and switching of the inverter can be reduced without increasing speed fluctuation and vibration at low speed. .

  According to a fourth aspect of the present invention, the voltage applied to the auxiliary coil is turned off at high speed operation and at a low load, and the loss due to energization to the auxiliary coil and switching of the inverter without impairing the operating range, increasing the speed fluctuation or vibration. Can be reduced.

(Embodiment 1)
FIG. 1 is a block diagram of a motor control device according to an embodiment of the present invention.

  In FIG. 1, a single-phase induction motor 1 having a main coil 1a and an auxiliary coil 1b is connected to an inverter circuit 2 composed of switching circuits 2a, 2b, 2c, 2d, 2e, and 2f. The current flowing through the coil 1b is output by the current detection circuit 3 as the main coil current IR and the auxiliary coil current IS.

  The inverter circuit 2 is connected to a DC power source 4, and the DC voltage is output as a DC voltage VD by the DC voltage detection circuit 5.

Next, the control circuit 6 for controlling the speed of the induction motor 1 is:
Voltage calculation means 7 for calculating main coil voltage command VR and auxiliary coil voltage command VS to be applied to the main coil and auxiliary coil from frequency command FC, main coil current IR and auxiliary coil current IS, DC section voltage VD and main coil voltage VD PWM signal generating means 8 for outputting drive signals Pa to Pf of the switching circuits 2a to 2f by pulse width modulation from the coil voltage command VR and the auxiliary coil voltage command VS, and a drive signal from the frequency command FC and the main coil current IR. It comprises signal correction means 9 that corrects Pc and Pd and outputs them as corrected drive signals Pc2 and Pd2, and drives the switching circuits 2a to 2f of the inverter circuit 2 to control the induction motor 1.

  Here, although detailed operations of the voltage calculation means 7 and the signal correction means 9 will be described later, the voltage variable technique based on pulse width modulation performed by the PWM signal creation means 8 is known, and the description thereof will be omitted.

  Next, FIG. 2 is a detailed block diagram of the voltage calculation means 7.

  In FIG. 2, the main coil V / F converter 10 outputs a main coil basic voltage command VR0 according to the V / F characteristics of the main coil set in advance from the frequency command FC, and the main coil voltage corrector 11 outputs the main coil current. A voltage proportional to the difference from the main coil rated current set in advance from IR is added to the main coil basic voltage command VR0 to output the main coil voltage command VR.

  Similarly, the auxiliary coil V / F conversion unit 12 outputs the auxiliary coil basic voltage command VS0 according to the V / F characteristic of the auxiliary coil set in advance from the frequency command FC, and the auxiliary coil voltage correction unit 13 outputs the auxiliary coil current IS. A voltage proportional to the difference from the preset auxiliary coil rated current is added to the auxiliary coil basic voltage command VS0 to output the auxiliary coil voltage command VS.

  Next, FIG. 3 is a detailed block diagram of the signal correction means 9.

  In FIG. 3, the FC determination unit 14 determines that the frequency command FC is preset as F1 as a threshold value, and determines that the low speed side is ON and the high speed side is OFF, and outputs a determination result FJD.

  In addition, the IR determination unit 15 prepares two values of I1 set in advance and I2 larger than I1, and when the previous determination result IJD is ON, I1 is set as a threshold value, and is OFF on the low current side and ON on the high current side. On the other hand, if the previous determination result IJD is OFF, I2 is set as a threshold value, it is determined OFF on the low current side, and ON on the high current side, and a new determination result IJD is output.

Further, the signal correction unit 16 outputs Pc2 and Pd2 as OFF regardless of the signals of Pc and Pd when FJD and IJD are both OFF from the combination of the determination results FJD and IJD, and outputs either FJD or IJD. When ON, the Pc and Pd signals are output as they are as Pc2 and Pd2.

  Since the signal correction means 9 turns off Pc2 and Pd2 during high-speed operation and low load, both the switching circuits 2c and 2d are not energized to the auxiliary coil 1b. Therefore, voltage application to the auxiliary coil 1b is not performed. It is turned off.

  As described above, the motor control device of the present invention operates with high efficiency by turning off the voltage application to the auxiliary coil depending on the operating state, and thus can be applied to various single-phase induction motor control devices.

Block diagram of motor control apparatus according to Embodiment 1 of the present invention Detailed block diagram of voltage calculation means 7 Detailed block diagram of the signal correction means 9

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Induction motor 1a Main coil 1b Auxiliary coil 2 Inverter circuit 2a, 2b, 2c, 2d, 2e, 2f Switching circuit 3 Current detection circuit 4 DC power supply 5 Voltage detection circuit 6 Control circuit 7 Voltage calculation means 8 PWM signal preparation means 9 Signal Correction means 10 Main coil V / F conversion unit 11 Main coil voltage correction unit 12 Auxiliary coil V / F conversion unit 13 Auxiliary coil voltage correction unit 14 FC determination unit 15 IR determination unit 16 Signal correction unit

Claims (4)

A single-phase induction motor having a main coil and an auxiliary coil, a current detection circuit for detecting a motor current flowing in the single-phase induction motor, an inverter circuit for outputting a voltage supplied from a DC power source by pulse width modulation, and A DC voltage detection circuit for detecting a DC voltage input to the inverter circuit, a voltage calculation means for calculating a voltage command to be applied to each coil of the single-phase induction motor from a frequency command and the motor current, and the voltage command And a DC signal generating means for outputting a control signal for operating the inverter circuit from the DC section voltage, and a signal correcting means for correcting the control signal, and the signal correcting means depending on the operating state of the single-phase induction motor Corrects the control signal so that voltage application to the auxiliary coil is turned on or off. 2. The motor control device according to claim 1, wherein the voltage application to the auxiliary coil is turned off when the load is low except during starting. 2. The motor control device according to claim 1, wherein voltage application to the auxiliary coil is turned on during low-speed operation including start-up. 2. The motor control device according to claim 1, wherein voltage application to the auxiliary coil is turned off at high speed operation and at a low load.

Images