JPS6016182A - Restarting method of motor - Google Patents

Abstract

PURPOSE:To smoothly restart from the course of deceleration by controlling the frequency, voltage and phase of an inverter when a motor is stopped, thereby controlling the deceleration of the motor. CONSTITUTION:If a motor stop command is outputted when a motor 3 is operated by the set frequency by an inverter 2, a microcomputer 5 controls the frequency, voltage and phase of the inverter 2 to control the deceleration of the motor 3. When the operation command of restart is inputted from an operation panel 6 to a microcomputer 5 in the course of decelerating the motor 3, the inverter 2 is switched to acceleration while maintaining the frequency, voltage and phase control. In this manner, the restart can be performed in a short time smoothly.

Description

[Detailed description of the invention] The present invention relates to a method for restarting an electric motor.

FIG. 1 is a block diagram illustrating an electric motor operating device. DC power obtained from a converter 1 is converted into variable frequency, variable voltage AC power by a transistor voltage inverter 2 to drive a permanent magnet electric motor (or 4 is a smoothing capacitor.The inverter 2
The gate control signal is given from the inverter interface 7: L-sjg of the microcomputer 5. The microcomputer 5 has inverter control, for example P
RO that stores the software program for WM control
M52, R□ M 5 s % μm0PU5a, which stores parameter data such as various setting values set by the operation panel described later and data for calculations, and obtains the output signal of the inverter 2 according to a program using each of these data. , operation panel interface 5
B and a pass line 56.

6 is an operation panel, and this operation panel 6 has a setting device for setting the operating frequency of the inverter 2 (rotational speed control of the motor) and acceleration/deceleration commands for the electric motor 3, and the signal d from this setting device is for the operation panel. It is led to a back line 56 through an interface 55.

A conventional motor operating method in the motor operating device configured as shown in FIG. 1 will be described with reference to FIG. FIG. 2 is a time chart of a conventional operation pattern, in which the vertical axis represents the motor rotation speed n and the horizontal axis represents time t. In this FIG. 2, from time t=0 to 1=1.
The patterns up to this point indicate a state in which the electric motor is operated at a set frequency (predetermined rotational speed n+'). When operating in this way, the time 1 = 1. When a stop command is input from the operation panel 6 to the gate of the inverter 2 at this time, the inverter 2 stops operating. As a result, power supply to Simi Motion 3 is cut off. However, the electric motor 3 continues to rotate due to inertia, and the rotation speed gradually decreases as time passes. The deceleration pattern at this time is shown by curve Z in FIG. Time t in the diagram! is i of electric motor 3
This is the point at which the rotation stops.

In particular, in the case of the electric motor 3 having a large qD value, it may continue to rotate for several tens of minutes from when a stop command is input until it stops. In this way, when the motor with a large qpl is, for example, a permanent magnet motor PM, an induced voltage is generated until the motor stops. In such a case, from the time t1 to 1. If a restart operation command is input to the inverter 2 during this period, the frequency, voltage, and phase will not match between the motor PM and the inverter 2, resulting in output overcurrent and DC overvoltage.

Due to these, the inverter 2 breaks down and stops operating. Furthermore, even if the motor with a large qD3 is, for example, an induction motor M, a restart command is input to the inverter 2 and a DC overvoltage is generated by the power pack etc. at 9 o'clock, so the inverter 2 may fail. Put it away.

In addition, in FIG. 2, the period from time t2 to t3 is a time for confirming that the rotation of the electric motor 3 has stopped. In this way, conventionally, a restart command was not given until rotation had completely stopped. At time t3, the driving command is input, and according to this command, the υ motor 3 is accelerated until time t4 according to the acceleration command curved edge Y in the figure. And the rotation speed is the set value n
If it matches 1, it enters the operating state at synchronous speed.

As mentioned above, in the conventional electric motor operation method, after stopping the inverter and cutting off the power supply to the electric motor, it is not possible to restart the electric motor for more than several tens of minutes until the rotation of the electric motor has completely stopped. is used inefficiently. Even if a restart command was given while the electric motor was rotating due to inertia, the operation of the inverter would stop, making it impossible to restart the electric motor.

This invention was developed in view of the above-mentioned circumstances, and allows a microcomputer to give a motor stop command to a variable speed inverter to control the frequency of the inverter, 'l! The purpose of the present invention is to provide a method for restarting an electric motor that enables smooth restart operation by controlling the pressure and phase, then decelerating the electric motor, and restarting the motor during the deceleration control. .

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a time chart of the operation pattern for stopping and restarting the electric motor according to the present invention, and it is assumed that until time 11, the electric motor 3 is operated at the specified frequency by the inverter 2 shown in FIG. .

While operating in this manner, a motor stop command is sent from the operation panel 6 shown in FIG.

The microcomputer 5 to which this command has been input does not send a gate cutoff output to the inverter 2, but sends an output for frequency, voltage, and phase control to control the motor 3 for a time of 1. Control the deceleration. In FIG. 3, Z is the deceleration control curve. While the electric motor 3 is being decelerated according to the deceleration control curve Z, when a restart operation command is input from the operation panel 6 to the microcomputer 5 at time t2, the inverter 2 maintains frequency, voltage, and phase control. The engine is then switched to acceleration control and restarted. Y is an acceleration control curve. After restarting, according to the acceleration control curve Y,
The electric motor 3 is accelerated until time t3. When the rotational speed of the electric motor 3 reaches time j++, it matches the set value and thereafter enters the operating state at the synchronous speed.

As described above, the frequency, voltage, and phase of the inverter 2 are controlled even during deceleration control, so even if you switch to acceleration control from the middle of deceleration control, the motor 3 will restart smoothly regardless of the magnitude of GD. Since no overcurrent or overvoltage occurs, the operation of the inverter 2 does not stop.

In addition, this method requires no waiting time before restarting, so the motor is used very efficiently.

Next, in the time chart of the operation pattern shown in FIG. 3, the intersection point (time ta) where the deceleration control oil lsZ is extended to the time axis as shown by the dotted line is the point at which the electric motor according to the present invention is stopped, and the electric motor 3 is now in this position. Assume that when the engine has stopped at a low rotational speed close to the time of stopping, the inverter 2 is gated off, and then an operation command for restarting is sent from the operation panel 6 in the same manner as described above. At this time, since the electric Mtb machine 3 rotates at a low rotation speed, even if the frequency, voltage, and phase between the electric motor 3 and the inverter 2 do not match, power back or sudden acceleration current does not occur, and the machine restarts with the normal operation command. I can do it.

This is because each sound of the inverter is determined by the starting current, so the inverter does not stop operating.

As described above, according to the present invention, when a motor stop command is given to the variable speed inverter device from the micro combiator, the frequency of the inverter device.

Since the voltage and phase are controlled to decelerate the motor, and during this control, acceleration control is performed again, even a motor with a large GD2 can be restarted in an extremely short time, and moreover, it is possible to restart the motor in an extremely short time due to inverter failure, etc. It is also unlikely that the operation will stop. In addition, after the inverter gate is cut off when the motor rotates at low speed or has stopped, smooth restarting is possible when a restart command is received, and it also prevents operation from stopping due to inverter failure, etc. There are advantages such as not having to

[Brief explanation of drawings]

Fig. 1 is a block diagram illustrating a motor operating device using a microcomputer, Fig. 2 is a time chart showing a restart operation pattern of a conventional motor, and Fig. 3 is a diagram of a motor showing an embodiment of the present invention. It is a time chart of a restart operation pattern. 20.Inverter 130.Electric motor, 5++-.Microcomputer, 6.--Operation panel.

Claims (2)

[Claims] (1) In a method of operating an electric motor controlled by the output of a variable speed inverter device, a motor stop command is given to the variable speed inverter device from a microcomputer, and the frequency, voltage and phase of the inverter device are controlled to drive the electric motor. A method for restarting an electric motor, characterized in that the microcomputer gives a motor acceleration control command to a variable speed inverter device during deceleration control. (2) In a method of operating an electric motor controlled by the output of a variable speed inverter, a motor stop command is given to the variable speed inverter from a microcomputer, and the frequency, voltage and phase of the inverter are controlled to drive the electric motor. By this control, when the electric motor stops or operates at low rotation speed, the gate of the inverter device is cut off, and then a restart command is given to the electric motor to accelerate the electric motor. Characteristic method of restarting an electric motor.