SU1422345A1 - Device for delta to star switching of induction motor stator winding phases - Google Patents

Abstract

The invention relates to electrical engineering and can be used to control electric motors, the load of which varies over a wide range. The aim of the invention is to improve the reliability of the device. The device contains an active power meter 1, a controlled switch 2, a threshold element 3, a one-shot 4 and an OR-NOT 5 logic element, a second threshold element 7, an integrator 8, a proportional adder 9 and a trigger 10. The device allows for a clear phase switching of the stator winding electric motor 6 from the Triangle diagram to the Star and vice versa scheme with a smooth variation of the load moment, and through the use of integrator 8 and two threshold elements 3 and 7, improve the quality of regulation by taking into account the speed Neni controlled parameter that complements .nitelno Increases functional reliability nirovani. 1 hp f-ly, 2 ill. "Cl

Description

four:

go

N9

CO 4 01

FIG. g

The invention relates to the field of electrical engineering and can be used (but for controlling electric motors whose load varies widely.

i The purpose of the invention is to increase the reliability of the device.

FIG. 1 and 2 are structural diagrams of a device for switching the phases of the stator winding of an avchronous motor.

I The device contains a meter of active power 1, a control of the crochet 2, the first threshold element 3, the one-shot 4 and the element OR-NOT 5 The inputs of the one-shot 4 and the first threshold element 3 are combined and connected to the output of the power meter 1 and the outputs of the one-vibrator l | a 4 and the first threshold element 3 are connected to the inputs of the OR-NOT $ element, the output of which is connected to the control input of the controlled switch 2, designed to switch the phases of the stator winding of the electric motor 6 from the circuit Triangle on the Zve scheme yes (Fig. 1).

In addition, a device for switching phases of the stator winding of an electric motor from a Triangle circuit to a Star-yes circuit contains a second threshold element 7, an integrator 8, a proportional adder 9 and a trigger 10 the first input of the proportional sum-: the mat 9 directly, and the second input through the integrator 8 is connected to the output of the meter 1 active power. The connection of the output of the element OR NOT 5 with the control input of the controlled switch 2 is made via trigger 10, the second input of which through the second threshold element 7 is connected to the output of the proportional adder 9 (Fig. 2).

The device works as follows.

When the motor 1 is turned on by the starter (not shown) switch 2 is in the initial position, and the stator winding phase of the motor 6 is connected according to the Triangle scheme, but since at the first moment the current through the motor 6 is small, although it rises, the output signal The active power meter is small, the threshold element 3 is turned off, and the signal at its output is zero. However, at the time of admission

Q

5 0 5

Q

five

0

five

the supply voltage triggers a single-vibrator 4, which gives a pulse with a duration longer than the acceleration time of the electric motor 6, which prohibits the operation of switch 2. If the signal from the single vibrator 4 ends, the signal from the output and the active power meter 1 exceeds the threshold of the threshold element 3, the switch 2 the stator winding of the electric motor 6 remains connected according to the Triangle scheme. Otherwise, switch 2 switches the phases of the stator winding of the electric motor 6 to the Star circuit. Further, the switching circuit of the motor 6 is uniquely determined by the value of its active power.

With the introduction of devices about the integrator 8, proportional to the adder 9 and the trigger 10 (Fig. 2), the device works as follows.

The output signal from the meter 1 active power is supplied to the first threshold element 3 directly. If the power consumed by the electric motor 6 is less than a certain level, a zero signal is generated at the output of the threshold element 3 and if there is no signal from the output of the single vibrator 4 and the second threshold element 7, the unit is formed at the output of the OR-NO 5 element, the switch 2 turns on the stator motor windings according to the scheme Star. With an increase in power consumed by the electric motor 6, as well as with a rapid increase in load, the signal at the output of the proportional adder 9 grows. When the signal at its output exceeds the threshold of the threshold element 7. Switch 2 switches the phases; stator motor winding on the Triangle circuit. The presence of an integrator 8 and two threshold elements 3 and 7 allows to obtain different dynamic characteristics of the device.

Thus, the invention allows for clear switching. phases of the stator winding of an electric motor with a smooth change in the torque of the electric motor.

. In addition, the device of FIG. 2 improves the quality of regulation by taking into account the rate of change of the controlled parameter (with a sharp increase in load, switching from

The stars on the Triangle occur earlier), which further improves the operation of the device.

Claims (2)

1. A device for switching the phases of the stator winding of an induction motor from a Triangle to a Star circuit, containing an active power meter and a controlled switch, characterized in that, in order to increase the reliability of the device, a first threshold element, a single vibrator and an OR element are introduced into it NOT, the inputs of the one-shot and the threshold element are combined and connected to the output of the active power meter, and the outputs of the one-shot and the threshold element are connected to the corresponding one. 0 The element inputs are OR NOT, the output of which is connected to the control input of the controllable switch. 2. The device according to claim 1, characterized in that, in order to further increase the reliability of the device, a second threshold element, an integrator, a proportional adder and a trigger, the first proportional adder input is entered, and the second proportional adder input is connected via an integrator to the measurement output5 Active power bodies indicated by the connection of the output of an OR-NOT element with a control input of a controlled switch are made via a trigger, to the second input of which through a second threshold element unplugged output proportional adder.