JP2526179Y2 - Servius control circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of the Invention The present invention relates to a Selvius control circuit for an induction motor.

B. Outline of the Invention The present invention relates to an induction motor in which a starting resistor is connected to a secondary side via a starting contactor and a static Selvius controller is added. A bias signal to be added to the SELVIUS setting command is generated at the AND stage of the starting contactor and SELVIUS contactor at the front stage of the amplifier, and the speed-up command to which the SELVIUS setting command bias signal is added does not exceed the maximum speed with the limiter amplifier. In this way, the signal is input to the cushion amplifier, and the Servius contactor is turned on, and the control is shifted to the Servius control from the time of the maximum speed, and even if the speed at the time of the starting resistor minimum notch is high, the control can be smoothly shifted to the Servius control. It was made.

C. Prior Art FIG. 1 shows a speed control circuit of an induction motor in which a static Selvius control device is added to an induction motor using a starting resistor for energy saving and the like. In FIG. 1, IM is an induction motor connected to a power supply AC via a circuit breaker CB1, MC1 and R1 are starting contactors and starting resistors provided on a secondary side of the motor, SW
1 is a slip ring short-circuit device that short-circuits the secondary side upon completion of startup, 10 is an additional SELVIUS control device, 11 is a converter connected to the motor secondary via a SELVIUS contactor MC2, and 12 is a converter 11 Inverter connected via DC reactor DCL and DC circuit breaker CB2, T1 boosts the output of inverter 12 and supplies AC power via circuit breaker CB3.
This is a transformer that returns power corresponding to the secondary resistance loss of the motor to the side.

As shown in FIG. 4, a Servius control circuit for controlling the inverter of the Servius control device inputs a Servius setting command S to a speed amplifier 22 in association with a speed detection signal N through a cushion amplifier 21. The command is further input to the current amplifier 23 in association with the current detection signal I, the current command of the current amplifier is integrated by the integrator 24, and the output thereof is input to the gate phase control circuit 25. Is controlled in phase.

D. Problems to be solved by the present invention As described above, when the existing equipment is equipped with a SELVIUS control circuit to the induction motor using the activating resistor, the secondary activating resistor is larger than the minimum speed of the SELIVIS control range (the cam controller A motor having a high speed at the time of the notch does not smoothly shift to the Servius control for the following reason (see FIG. 5).

Minimum speed N ₃ of Scherbius control is lower than the starting resistance minimum notch speed N _2.

Since the speed N ₂ is between the free-run deceleration of N _3, deceleration time t _f is changed by the load.

The speed is decelerated by free-run to the minimum setting of Servius, and it tries to shift to Servius control. However, it is out of the Servius speed range due to control operation delay, etc., and the starting resistor is turned on again. A DC overvoltage fault will occur.)

When the speed detection signal N and the Servius set speed S change from N> S to S> N and enter Servius control, a sudden change in current and load occurs (see FIG. 6).

If the load is heavy, the free run deceleration is fast and there is a control delay time, so that the load falls outside the Servius speed range and the starting resistor is turned on again. This repetition heats the resistor. For this reason, 1) When shifting from the starting resistor to the Servius control, current and load fluctuations are large.

2) Depending on the load condition, it is out of the control range of Selvius,
The starting resistor turns on and off and accelerates.

3) If the setting of the speed comparator outside the Servius control range is low, it will stop due to a DC overvoltage failure. There are problems such as.

The present invention has been made in view of such problems of the prior art, and the purpose is to convert the existing starting resistor to the Servius control without making the resistance value a problem. It is an object of the present invention to provide a Servius control circuit which can be used.

E. Means for Solving the Problems In order to achieve the above-mentioned object, the Selvius control circuit in the present invention includes a stationary Selvius control device for an induction motor having a starting resistor connected to a secondary side via a starting contactor. In addition, a bias generation for generating a bias signal to be added to the Servius setting command in the AND condition of the starting contactor and the Servius contactor at a front stage of the Servius control circuit cushion amplifier to which the Servius setting command of the Servius controller is input. A speed-up command circuit comprising a circuit, and a limiter amplifier for receiving a speed-up command based on the bias signal of the cell-vius setting command to which the bias signal of the cell-vius setting command to which the bias signal is added does not exceed the maximum speed. It is.

F. Action The starting contactor is turned ON and the notch of the starting resistor is switched to the maximum speed.In this state, the SELVIUS contactor is turned ON, the starting resistor notch is set to the minimum, and the starting contactor is turned OFF. A bias signal is generated by an AND condition between the starting contactor and the Servius contactor. This bias signal is added to the Servius setting command, and the speed-up command to which the bias signal is applied is limited to the maximum speed by a limiter amplifier so that the speed-up command does not exceed the maximum speed. Decreases due to the characteristics of the cushion amplifier. For this reason, the motor is operated at the maximum speed by the speed-up command when the Servius contactor is turned on, and when the start switch is turned off, the operating speed is reduced to the Servius setting command speed due to the cushion amplifier characteristic.
Therefore, even if the speed of the starting resistor when the notch of the starting resistor is turned off at the time of turning off the start switch is higher than the minimum setting speed of Servius, free-running occurs during the transition from the turning off of the start switch to the minimum setting speed of Servius. No, it is possible to smoothly enter the Servius control operation.

G. Embodiment FIG. 2 shows a Servius control circuit. The same components as those shown in FIG. 4 are denoted by the same reference numerals, and redundant description will be omitted.

In FIG. 2, reference numeral 13 denotes a speed-up command circuit, which is a series circuit (AND condition circuit) of the auxiliary contact MC2-2 of the Servius contactor MC2, the auxiliary contact MC1-2 of the starting contactor MC1, and the relay RY1, and a bias signal. a voltage dividing resistor R2 to generate, and input bias signal S _B is Scherbius signal applied which is output from the contact Ry1 of the relay RY1 to Scherbius signal S, is composed of a limiter amplifier 14 for output to cushion the amplifier 21 ing.

Next, the operation of the speed-up command circuit 13 will be described with reference to the chart of FIG.

Starter contactor MC1 and in the ON electric motor is charged with Scherbius contactor MC2 in time when a cam controller (Kamukon) Maximum notch speed N ₁ and Scherbius control, starter contactor MC1 starting contactor MC1 as Kamukon minimum notch OFF
And The auxiliary contacts MC1-2, MC2-2 of these contactors MC1, MC2
When the relay RY1 that operates under the AND condition of
Speed up bias signal S set from Ry1 by resistor R2
_B is added to the SELVIUS setting command S, and the speed-up command to which the bias signal is added passes through the limiter amplifier 14 for limiting the speed-up command so as not to exceed the maximum speed, and the speed-up command as shown in FIG. A SELVIUS setting command S 'having a characteristic that the trailing edge of the portion is lowered by the cushion is output.

Therefore, the electric motor IM receives the Selvius setting command S '.
Since controlled, since during the speed N ₂ and N ₃ is the speed decreases following the cushioning properties of the cushion amplifier, the free-run deceleration state does not occur during this time.

H. Effects of the Invention Since the invention is configured as described above, it has the following effects.

(1) It is possible to add and modify the Servius control device without worrying about the resistance value of the existing starting resistor.

(2) Since the control is always shifted from the maximum speed to the cushion setting so as to follow the cushion setting, when the operation shifts from the operation by the starting resistor to the Servius control, current and load fluctuations due to control delay and the like are small.

(3) Since the maximum speed is limited by the limiter amplifier, it is safe.

(4) It is not affected by load conditions.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a motor control circuit to which a cellvius control device is added, FIG. 2 is a block circuit diagram showing a cellvius control circuit according to an embodiment of the present invention, and FIG. 3 is a diagram for explaining the operation of the control circuit. FIG. 4 is a block circuit diagram showing a conventional cellvius control circuit, FIG. 5 is a graph for explaining the operation of the conventional circuit, and FIG. 6 is an explanatory diagram of the operation of the conventional circuit. IM: Induction motor, MC1: Starting contactor, MC2: Cellvius contactor, R1: Starting resistor, R2: Bias signal setting device, 10: Cellvius device, 13: Speed-up command circuit, 14 …… Limiter amplifier, 21 …… Cushion amplifier.

Claims (1)

(57) [Scope of request for utility model registration] 1. An induction motor in which a starting resistor is connected to a secondary side via a starting contactor, to which a stationary Selvius controller is added, wherein a Servius control circuit cushion to which a Servius setting command of the Servius controller is inputted. A bias generating circuit for generating a bias signal to be added to the SELVIUS setting command under the AND condition of the starting contactor and the SELVIUS contactor at the front stage of the amplifier, and a SELVIUS setting command to which the bias signal is added is input. A speed-up command circuit comprising a limiter amplifier for preventing the speed-up command by the bias signal from exceeding the maximum speed.