JP4164646B2 - Motor decelerating stop control method and motor variable speed drive device during power failure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a deceleration stop control method and a motor variable speed drive apparatus during a power failure of a motor driven at a variable speed by an AC servo amplifier or an inverter.
[0002]
[Prior art]
Conventionally, as a control method for decelerating and stopping the motor in the event of a power failure in an AC servo drive or inverter drive, the motor is decelerated and stopped by the speed command sudden deceleration and is required for powering operation until regenerative power is generated. A capacitor for storing only the energy was added and the speed command was given as shown in FIG.
[0003]
[Problems to be solved by the invention]
However, if a power failure is detected at time t ₀ in FIG. 3 and the actual motor speed is lower than the current speed command at time t ₁ when the speed command is actually started to decelerate, a power running operation is performed on the motor. In addition, in order to prevent the _{VDC in} FIG. 1 from being lowered in the drive unit as well as an alarm due to insufficient voltage, more capacitors are required. There is a problem that the apparatus becomes expensive and the apparatus becomes large.
Accordingly, an object of the present invention is to provide a control method for decelerating and stopping a motor at the time of a power failure with a smaller capacitor capacity.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention starts the deceleration from a place several percent lower than the speed calculated by moving and averaging the speed feedback for the speed command to decelerate and stop the motor after detecting the power failure at the time of power failure. Further, when the torque command becomes the power running operation side at that time, the torque command is forcibly set to zero.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on specific examples.
FIG. 1 is a configuration example of an apparatus to which the present invention is applied. 1 is a forward conversion unit, 2 is an inrush current suppression resistor, 3 is an inrush current suppression MC, 4 is a smoothing capacitor, and 5 is an undervoltage prevention device. External capacitor, 6 reverse conversion unit, 7 motor, 8 speed detector, 9 speed command calculation unit, 10 speed controller, 11 torque command limiter, 12 torque command limiter setting unit, 13 speed feedback , 14 is a speed command, 15 is a torque command, and 16 is a final torque command.
Necessary for powering operation of the motor 7 until the three-phase AC power input to the forward conversion unit 1 is lost due to a power failure and this is detected and the speed command calculation unit 9 gives a rapid deceleration command. The energy is N ₂ , the speed after free running for T ₁ time from the occurrence of power failure t ₀ to the speed command deceleration start point t ₁ during operation at speed N ₁ , the moment of inertia of the motor and load is G _D ² , efficiency was a n _2, G _D ² moment of inertia of the motor and the load, efficiency When ^{_{n E 1 = G D 2/}} 730 (n 1 2 -N 2 2) n [J] ··· (1)
It becomes. At this time, in order to prevent the V _DC in FIG. 1 from becoming below the undervoltage alarm detection voltage V _UV , _assuming that the voltage before the power failure is V _DCO , C ₁ = 2E ₁ / V _DC0 ² −V _UV ² [F]・ (2)
However, since the smoothing capacitor 4 of the normal driving device is not sufficient, an undervoltage prevention capacitor 5 must be added to the outside.
However, at time t ₁ gave rapid deceleration command, if the speed N _a as shown in FIG. 2 was equal to or lower than the speed command N _0, for immediately entering the regenerative operation, is not sufficient only C _1, It is necessary to add more capacitors.
Therefore, when the speed feedback 13 detected by the speed detection unit 8 is moving averaged to calculate the motor speed and the deceleration command 14 is given from the speed command calculation unit 9, the speed N _a at that time as shown in FIG. Therefore, a command to decelerate from the α% lower speed is given so that N _a does not become N ₀ or less, and when the torque command 15 that is the output of the speed controller 10 is on the power running side, Therefore, the torque command 15 is made zero by the torque command limiter 11 to prevent the motor operation from being on the power running side.
[0006]
【The invention's effect】
As described above, according to the present invention, in an apparatus that drives a motor at a variable speed by an AC servo amplifier or an inverter, the capacity of an additional capacitor is reduced to prevent an undervoltage alarm that occurs due to a power failure during operation. It is possible to reduce the cost and prevent the apparatus from becoming large.
[Brief description of the drawings]
FIG. 1 is a basic configuration of an apparatus to which the present invention is applied.
FIG. 2 is a speed command when the motor is decelerated to a stop according to the present invention.
FIG. 3 is a speed command at the time of motor deceleration stop in the prior art.
[Explanation of symbols]
1 Forward conversion part 2 Inrush current suppression resistor 3 Inrush current suppression MC
4 Smoothing Capacitor 5 External Voltage Prevention Capacitor 6 Reverse Conversion Unit 7 Motor 8 Speed Detector 9 Speed Command Calculation Unit 10 Speed Controller 11 Torque Command Limiter 12 Torque Command Limiter Setting Unit 13 Speed Feedback 14 Speed Command 15 Torque Command 16 Final torque command

Claims (2)

In AC servo drive and inverter drive,
When the speed command (14) is given from the speed command calculation unit (9) , the speed command (Na) at the speed command deceleration start point (t ₁ ) does not fall below the speed command (No) at the time of power failure (t ₀ ). Thus, after detecting the power failure at the time of a power failure, a speed command (14) for decelerating and stopping the motor (7) is calculated by moving average the speed feedback (13) detected by the speed detection unit (8). given from the speed several percent lower at the to start decelerating, further this time, when the torque command (15) is turned power-running operation side, at forcing a torque command (15) the torque command limiter (11) zero A method for controlling deceleration and stopping of a motor at the time of a power failure. In AC servo drive and inverter drive,
When the speed command (14) is given from the speed command calculation unit (9) , the speed command (Na) at the speed command deceleration start point (t ₁ ) does not fall below the speed command (No) at the time of power failure (t ₀ ). Thus, after detecting the power failure at the time of a power failure, a speed command (14) for decelerating and stopping the motor (7) is calculated by moving average the speed feedback (13) detected by the speed detection unit (8). given from the speed several percent lower at the to start decelerating, further this time, when the torque command (15) is turned power-running operation side, at forcing a torque command (15) the torque command limiter (11) zero A motor variable speed drive device characterized by that.

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