JPH043599Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to prevention of reversal in a reversible Leonard.

Generally, when a reversible Leonardo comes to a stop, it rotates a little in the opposite direction and then comes to a complete stop, but this can be dangerous depending on the object being controlled, lengthens the stopping time, and even puts stress on gears, etc. It is also possible that the added force may shorten the lifespan.

In view of the above, this idea was developed by detecting the zero speed when the reversible Leonard stops, and when the speed drops to a "zero speed" value of 1/100 or 1/200 of the rated speed. Short-circuit the input and output of each regulator to reduce the output level of each regulator with large amplification to the input side level, that is, set the phase shifter input to zero to prevent commutation failure in the gate phase shift angle. The phase shift is made to a hard pulse position of about 150 to 160 degrees narrowed down to the deepest position to prevent the motor from reversing.The details will be explained below based on an embodiment shown in the drawings.

As for the drawings, FIG. 1 is an overall configuration diagram of the thyristor Leonard control device, and FIG. 2 is a time chart for explaining its operation. In Figure 1, 1
2 is the speed command device that sets the command speed N, and 2 is the motor speed Nf from the command speed N and the speed detector 11.
Speed regulators 3 and 4 that find and amplify the deviation between
are current regulators for forward rotation and reverse rotation, respectively, which amplify the difference between the current command output from the speed regulator 2 and the current feedback signal from the current detector 10 and use it as an input signal to the phase shifters 6 and 7. In addition, the current regulator 4 for reverse rotation is
A code converter 5 is interposed between the speed controller 2 and the speed regulator 2 to invert the current command and supply an armature current in the opposite direction. 8 and 9 are forward converters for forward rotation and reverse rotation, respectively, and 12 is a DC motor.

This idea is based on the general Leonard control system mentioned above, where the motor speed is 1/100 or 1/2 of the rated value.
When the zero speed of 00 is reached, the inputs and outputs of the speed regulator 2 and current regulators 3 and 4 are short-circuited for a short time to make the inputs of the phase shifters 6 and 7 zero. A zero speed detector 21 detects the zero speed of the electric motor 12, and the output of the detector is maintained for a certain period of time, during which the relay X23 is operated to decelerate the electric motor due to inertia.
The differentiator 22 to be stopped and the relay X23 to short-circuit between the input and output of each regulator are attached to the motor speed feedback system.

The operation will be explained based on FIG. As shown in FIG. 2, when the motor 12 receives a stop command at time t1 (speed command N is zero), the forward rotation relay XF stops operating, the input signal to the phase shifter 6 becomes zero, and the motor 12 transitions from the drive state to the regeneration state. To avoid a power short circuit between the forward and reverse converters 8 and 9, the reverse relay
is turned on, the current regulator 4 for reverse rotation and the phase shifter 7 operate as a speed braking system, and the forward converter 9 for reverse rotation is phase-shift controlled so that the armature current flows in the opposite direction to that during normal rotation. Of course, as shown, the electric motor 12 continues to rotate in the forward direction, and this armature current acts as a control current, and a braking force acts on the electric motor 12, causing the motor speed to rapidly decrease. In this way, the electric motor 12 decreases to near zero speed (time t3), and the zero speed detection circuit according to the present invention is activated, that is, an output is generated to the zero speed detector 21 and maintained for a certain period of time by the differentiator 22. During this time, relay X23 is energized, and the input and output of the speed regulator 2, current minor loop forward rotation current regulators, and reverse current regulators 3 and 4 of the speed control system are short-circuited. In the case of the embodiment, the input signal of the phase shifter 7 for reversal becomes zero (the input signal of the phase shifter 6 for forward rotation is already zero because the relay XF is not activated), and the gate phase of the forward converter 7 for reversal reaches the kick pulse position. This causes the braking current to rapidly decline. As a result, the motor 12 gradually reduces its speed without reversing, and comes to a complete stop at time t4, after which a certain period of time determined by the differentiator 22 ends, and the input/output short circuit of the regulators 2, 3, and 4 is released.

In this way, the present invention provides a reversible Leonard device of this type in which, when stopped, the braking current is fed back in the form of a command signal, and the device rotates in the opposite direction for a short period of time, and then stops. This phenomenon, which can be dangerous depending on the controlled object and may have an adverse effect on gears, etc., is prevented by an extremely simple configuration that includes a zero speed detection comparator, a differentiator, and a relay device. do.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the embodiment, and FIG. 2 is a time chart for explaining its operation. 2...Speed regulator, 3...Forward rotation current regulator,
4...Reverse current regulator, 12...DC motor,
21... Zero speed detector, 22... Differentiator, 23...
...Relay for each controller short circuit.

Claims (1)

[Scope of utility model registration request] The main components are a main circuit formed by connecting two sets of forward converters 8 and 9 in antiparallel to each other, and a speed regulator 2 that compares the speed command and motor speed and controls the difference to zero. Speed control loop, speed regulator 2
A current minor loop for forward rotation consisting of a current regulator 3 for forward rotation and a phase shifter 6 for forward rotation, which compares the current command of the motor current with the motor current and controls the difference to zero; A current minor loop for reversal is formed by inserting the phase shifter 7 and a sign converter 5 for reversing the current command, and is inserted into the input side of the phase shifter 6 for forward rotation in order to input the current minor loop for either forward rotation or reverse rotation. It consists of a control circuit consisting of a forward rotation relay XF and a reverse rotation relay
By switching the operation of XR, the Leonard control system supplies a negative feedback signal of the motor speed to the system and applies a braking current commensurate with the speed to cause sudden deceleration. A zero speed detector 21 to detect and a differentiator 22 to maintain the output of this zero speed detector 21 for a certain period of time.
The zero speed detection circuit consists of a 1. A reversal prevention device for Leonard control, characterized by comprising a relay circuit 23 that makes the inputs of the devices 6 and 7 zero.