JPS61227694A - Transistor motor in ac exciting system - Google Patents

Abstract

PURPOSE:To realize a brushless transistor motor, by a method wherein polyphase current which is amplitude-modulated with the trapezoidal wave AC of bias frequency is made to flow to stator polyphase windings. CONSTITUTION:An AC motor 1 is provided with a rotor having q shaft single phase short-circuit windings, and with balanced polyphase stator windings. Polyphase current waveform command which is synchronized with a rotor position and has an amplitude given by torque command and is modulated by trapezoidal wave AC, is generated from a current waveform arithmetic circuit 2. The waveform polyphase AC commanded by the polyphase current waveform command is generated from a PWM inverter, and the current is made to flow to the polyphase stator windings. Torque current is induced to the single phase short-circuit windings, and torque is generated.

Description

[Detailed Description of the Invention] This invention allows a polyphase current whose amplitude is modulated by a trapezoidal wave alternating current at a bias frequency to flow through the stator polyphase windings of an AC motor, thereby pulsating at the bias frequency and synchronizing with the rotor. creates a magnetomotive force that rotates.

pulse! & It is characterized by realizing a transistor motor with a brushless structure by creating magnetic flux and inducing a torque current in the short-circuited rotor single-phase winding.

Examples of the present invention will be described as follows.

As shown in FIG. 1, the device of the present invention is an AC motor (1) consisting of a rotor with a q-axis short-circuited winding and a balanced multi-phase stator winding (1) (0) synchronized with the rotor position. (2) A current waveform calculation command circuit (2) that generates a polyphase current waveform command having an amplitude determined by the torque command and modulated by a trapezoidal AC waveform (c) PWM that generates a polyphase AC current with a commanded waveform.
It consists of an inverter (3).

When a multiphase alternating current (5, 6, ?) whose amplitude is modulated by a trapezoidal wave (4) at a bias frequency is passed through the stator winding, a single unit rotates in synchronization with the rotor, as shown in Figure 3. A pulsating magnetomotive force (9) similar to that obtained by passing a trapezoidal waveform alternating current through the phase winding (8) is obtained.

Of this pulsating magnetomotive force, the d-axis component (1o) becomes an excitation magnetomotive force and creates a trapezoidal wave pulsating magnetic flux φ (11) that rotates in synchronization with the rotor, while the q-axis component (12) , a torque current component of 1° (1
4), a torque (15) with φ1 (where τ is a constant) is generated. This torque includes pulsating torque whose fundamental wave is twice the bias frequency, but this does not pose a practical problem if the bias frequency is appropriately selected.

The modulation waveform can be arbitrary, but by adopting a trapezoidal waveform, the peak value of the magnetic flux is reduced compared to a sine wave, etc., so the cross-sectional area of the core is smaller, allowing for miniaturization, and the width of torque pulsation is reduced and the dead zone is eliminated. Effects such as being able to reduce

The AC motor of the present invention has a simple and robust brushless structure, and since there is no armature reaction, the gap length can be shortened, and by adopting trapezoidal wave modulation, it can be made as small as an induction motor.

When high-precision current control is required, such as in a servo system, in order to achieve high-speed current response, the inverter's voltage rating is usually designed to be high relative to the back electromotive force of the motor, and the rise of the trapezoidal wave is controlled appropriately. If designed, the excitation voltage required to pulsate the magnetic flux will not result in an increase in the voltage capacity of the inverter device.

As described above, the present invention applies an alternating magnetomotive force that pulsates in a trapezoidal wave while rotating at a synchronous angular velocity to excitation, and has a brushless structure transistor motor suitable for position control and small motors for relatively low-speed AC servos. This is to realize the following.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of an AC excitation type transistor motor, Figure 2 is the modulation waveform and stator winding current, and Figure 3'(a).
, (b) shows a principle diagram of an AC excitation type transistor motor. In the figure 1 = AC motor 2: Current waveform calculation command circuit 3
:PWM inverter 4: Trapezoidal modulation waveform 5.6.7:
Stator current waveform 8: Virtual single-phase winding 9: Pulsating magnetomotive force
10: d-axis component of pulsating magnetomotive force ll: pulsating magnetic flux 12:
Q-axis component of pulsating magnetomotive force 13: Rotor shorted winding 14:
Torque current component 15: Generated torque 'j41 Recurrence 3 figure

Claims (1)

[Claims] An AC motor consisting of a rotor with a single-phase shorted winding and a stator with a multi-phase winding, and a transistor P that drives it.
A brushless transistor motor is composed of a WM inverter and is excited by a trapezoidal wave pulsating magnetomotive force that rotates in synchronization with a rotor while pulsating at a bias frequency.