RU213868U1 - Variable AC drive with dual zone control for synchronous motor - Google Patents

Abstract

The proposed utility model relates to adjustable AC drives with two-zone control for a synchronous motor and can be used for smooth two-zone speed control of a synchronous motor. Adjustable two-zone AC electric drive, in which a synchronous motor with permanent magnets on the rotor is used as an electric motor, while an additional winding is added to the motor rotor, which, through a movable mechanical contact through which this winding is controlled, the supply alternating voltage is connected to the input of the converter frequency, the output of the frequency converter is connected to the first input of the switch block, the output of which is connected to the motor stator windings and to the contacts of the additional winding, and the second input of the switch block receives a signal from the output of the rectifier block, the input of which is connected to the AC supply voltage. 3 ill.

Description

The proposed utility model relates to adjustable AC drives with two-zone control for a synchronous motor and can be used for smooth two-zone speed control of a synchronous motor in high-precision machine tools with numerical control (CNC).

A known device is an AC electric drive with a synchronous motor, in which the AC supply voltage is connected to the stator windings, and the DC supply voltage is applied to the motor rotor windings (Voldek A.I. Electric machines. AC machines: A textbook for universities. - St. Petersburg: Peter , 2010 - S. 196).

However, the disadvantage of this device is the presence of only step speed control by changing the number of pole pairs.

The closest to the proposed utility model in terms of technical essence and the achieved result (prototype) is an AC drive with a synchronous motor with permanent magnets on the rotor when the stator windings are powered from an AC voltage network, in which the AC supply voltage is connected to the input of the frequency converter, the output of the frequency converter connected to the stator windings of a synchronous motor (Ledovsky A.N. Electric machines with high-coercivity permanent magnets. - M.: Energoatomizdat, 1985. - P. 19).

However, the disadvantage of this device is the inconsistency of the moment with two-zone control, which leads to a deterioration in the technological properties of the electric drive.

The objective of the proposed utility model is to control the speed of a synchronous motor in a wide range.

To solve this problem, in a regulated two-zone AC electric drive with a synchronous motor, in which a synchronous motor with permanent magnets on the rotor is used as an electric motor, characterized in that an additional winding is added to the motor rotor, which, through a movable mechanical contact, through which control is carried out this winding, the supply alternating voltage is connected to the input of the frequency converter, the output of the frequency converter is connected, according to the utility model, to the first input of the switch block, the output of which is connected to the motor stator windings and an additional winding located on the rotor of the synchronous motor, and to the second input of the switch block a signal is received from the output of the rectifier unit, the input of which is connected to the AC supply voltage.

By changing the flux linkage of the magnetic field of the stator and rotor with the help of a switch block, stepwise two-zone regulation of the motor rotation speed is provided, and by changing the frequency of the supply voltage, the frequency converter ensures smooth regulation of the rotation speed within each of the zones.

The proposed utility model is illustrated by drawings, where in Fig. 1 is a functional diagram of a two-zone controlled variable current drive for a synchronous motor, FIG. 2 - working bodies of the stator and rotor during operation without additional winding, in Fig. 3 - working bodies of the stator and rotor when working with an additional winding.

In addition, the drawings additionally show the following:

3f ~ - three-phase supply voltage;

A1, B1, C1 - stator windings;

C - synchronous motor stator;

P - engine rotor;

FC - frequency converter;

BK - block of switches;

IM - executive mechanism;

BV - block of rectifiers;

L1 - rotor windings;

Nm is the north pole of the permanent magnet;

Sm is the south pole of the permanent magnet;

M is a permanent magnet.

Adjustable two-zone AC electric drive, in which a synchronous motor with permanent magnets on the rotor is used as an electric motor, characterized in that an additional winding is added to the motor rotor, which, through a movable mechanical contact through which this winding is controlled, the supply alternating voltage is connected to input of the frequency converter, the output of the frequency converter is connected to the first input of the switch block, the output of which is connected to the motor stator windings and to the contacts of the additional winding, and the second input of the switch block receives a signal from the output of the rectifier block, the input of which is connected to the AC supply voltage.

The utility model comprises a motor rotor with a permanent magnet and a coil, a stator with excitation windings, a frequency converter, a rectifier unit, a switch unit, wherein the supply alternating three-phase voltage is connected to the input (1) of the frequency converter (2), the output (3) of the frequency converter (2 ) is connected to the first (4) input of the switch block (5), the outputs (6-11) of the switch block (5) are connected to the stator windings (12-14) and the additional rotor winding (15), the supply voltage (3f~) is connected to input (16) of the rectifier block (17), the output (18) of which is connected to the second (19) input of the switch block (5), the permanent magnet (20) is fixed on the rotor.

The work of the proposed utility model is as follows. When the motor is running without an additional winding, the switch block supplies power only to the windings A1, B1, C1, and the stator. Then, the supply voltage (3ph ~) is applied to the input (1) of the frequency converter (2), from the output (3) of the frequency converter (2) to the input (4) of the switch block (5), the operating voltage of the required frequency is supplied. From the outputs (6, 7, 8, 9) of the switch block (5), the operating voltage is supplied to the windings (12, 13, 14) A1, B1, C1. Thus, a rotating magnetic field with one pair of poles is formed on the stator of the synchronous motor, and one pair of poles is formed on the rotor due to the permanent magnet (20) (Fig. 2). The speed of rotation of the rotor is proportional to the frequency of the operating voltage.

When the motor is running with an additional winding, the switch block supplies power to the stator windings A1, B1, C1 and the rotor winding L1. Then, the supply voltage (3f~) is applied to the input (1) of the frequency converter (2), from the output (3) of the frequency converter (2) to the input (4) of the switch block (5), the operating voltage of the required frequency is supplied. From the outputs (6-9) of the switch block (5), the operating voltage is supplied to the windings (12) A1, (13) B1, (14) C1, respectively, the output (7) of the switch block (5) is connected to the common connection point of the stator windings. The supply voltage (3ph~) is supplied to the input (16) of the rectifier block (17), from the output (18) of which a constant voltage is supplied to the second (19) input of the switch block (5), from the outputs (10,11) of the switch block (5 ) DC voltage is applied to the additional winding (15) of the rotor (L1). Thus, a rotating magnetic field with one pair of poles is formed on the stator of the synchronous motor, and two pairs of poles are formed on the rotor due to the permanent magnet (20) and the coil (15) on the rotor (Fig. 3). The speed of rotation of the rotor in this case is determined by the change in the flux linkage of the magnetic fields of the stator and rotor, as well as by the frequency converter that controls the magnetic field of the stator.

Thus, based on the above, we can conclude that the proposed model allows:

1. Implement two-zone speed control by controlling the flux linkage of the magnetic fields of the stator and rotor.

2. Perform smooth speed control by changing the frequency of the supply voltage with one frequency converter for each zone.

3. The use of two-zone regulation allows the use of a simple frequency converter, since a wide range of regulation is carried out by changing the flux linkage of the stator magnetic field and the rotor magnetic field.

Claims (1)

Adjustable two-zone AC electric drive, in which a synchronous motor with permanent magnets on the rotor is used as an electric motor, the supply AC voltage is connected to the input of the frequency converter, the output of the frequency converter is connected to the first input of the switch block, the output of which is connected to the motor stator windings, and to the second input of the switch block receives a signal from the output of the rectifier block, the input of which is connected to the supply alternating voltage, characterized in that an additional winding is added to the motor rotor, which is connected through a movable mechanical contact to the output of the switch block, through which this winding is controlled.

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