KR19990043946A - Speed-torque characteristic adjustment method of switched reluctance motor - Google Patents

Abstract

Switched Reluctance Motors (SRMs) have superior operating characteristics compared to existing AC motors and are being considered for various applications as variable speed drive sources. However, SRM has high speed fluctuation rate due to the DC-torque characteristic of speed-torque, and it is difficult for variable speed operation. In this paper, we propose a method that can actively adjust the speed-torque characteristics of SRM to suit the load characteristics.

Description

Speed-torque characteristic adjustment method of switched reluctance motor

Switched Reluctance Motors (SRMs) have superior operating characteristics compared to existing AC motors and are being considered for various applications as variable speed drive sources. However, SRM has high speed fluctuation rate due to the DC-torque characteristic of speed-torque, and it is difficult for variable speed operation. In this paper, we propose a method that can actively adjust the speed-torque characteristics of SRM to suit the load characteristics.

Figure 1 shows the speed-torque adjustment principle in SRM. If the applied voltage and the dwell ahgle are adjusted, the speed-torque may be adjusted to a desired shape as shown in FIG.

The voltage equation of SRM is shown in equation (1).

In order to adjust the speed-torque characteristic, the speed feedback loop of the motor with respect to the reference speed is constructed. At this time, the speed detection of the motor is detected by a pulse signal by a simple disk encoder, and the reference speed is also pulsed. At this time, the motor speed is DC to F _M / V converter, and it is formed to reference speed V / F _R converter, but F _M / V and V / F _R converter adjust the conversion gain to change the conversion constant of frequency / voltage. Combine.

Now, the conversion formula of the F _M / V and V / F _R converter in FIG.

Therefore, when these are combined, they are identified under the following frequency conditions.

Thus, as shown in FIG. 3, the switching frequency and speed of the SRM can be adjusted by adjusting the bias voltages of both F / V converters. here, Is And Is the conversion constant of And Is their bias voltage.

The speed-torque characteristic in SRM is controlled by the magnitude of the current of the excitation electromotive force. And the magnitude of the current is controlled by the advance angle.

In the synchronizer, when the load torque increases or decreases, the phase difference increases and decreases, and the torque output proportional to its sine value responds quickly.

Torque control in this proposal introduces this principle, and if load torque is increased or decreased in SRM, the dwell angle of current is increased and decreased without additional computing device, and at the same time, it has effective torque output proportional to the square of instantaneous current to improve the dynamic characteristics of the motor. Made it possible.

Figure 4 shows a control conceptual diagram of maintaining a stable operation by varying the dwell angle in accordance with the change of the load torque at a constant speed. 4A shows a state where the load torque and the generated torque are in equilibrium. At this time, when the load torque decreases, the generated torque becomes larger than the load torque and the rotor is momentarily accelerated. As shown in (b) of FIG. 4, as the rotor speed increases, the pulse signal from the rotor position sensor is generated relatively early, so that the dwell angle is reduced, the magnitude of current is reduced, and the generated torque is also reduced. Thus, it operates at the conduction angle where the generated torque and the load torque are balanced, and the rotor speed is still equal to the reference speed.

On the contrary, when the load torque increases, the generated torque is smaller than the load torque and the rotor decelerates instantaneously. Therefore, as the switch-off signal is delayed in time, the dwell angle becomes wider as shown in FIG. 4 (c), and the generated torque increases to correspond to the load torque.

This operation can be confirmed by examining the pulse signal when the load increases in FIG. The reference speed signal is obtained from the speed command and the rotor speed signal can be obtained from the speed encoder attached to the rotor. From these two signals, a dwell angle can be generated, with the switching-on angle derived from the speed reference signal and the switching-off angle derived from the gray residue speed signal. At this time, the rotor encoder was installed in the rotor according to the switching-off angle. 6 is a shape suitable for 6/4 type SRM in the form of a rotor encoder.

The speed-torque adjustment operation is operated in the same manner as in FIG. 2 in a speed controller composed of an F _M / V and a V / F _R converter.

When the two converters are matched, as a compensation to the reference model for the impedance drop component in the voltage equation of Equation (1), the converted value of the average value I _L of the load current is returned to the reference value V / F _R , As a compensation for this, the converted value of the dwell angle is fed back to the motor speed feedback value F _M / V to adjust their bias voltage. Equation (3) has a relational expression as in Equation (4) below.

Where f _o is the motor speed frequency with the system identified, Is the load current Feedback coefficient, Is the feedback compensation coefficient of dwell angle θ _DW .

Where the feedback constant of the load current, And feedback coefficient of power (dwell) angle, If the drive system for adjusting the configuration is configured as shown in FIG.

9 is a ramp-type PWM pulse voltage to apply an appropriate phase voltage to the SRM using the dwell angle obtained from the schematic diagram of the voltage regulator.

10 shows the torque characteristics adjusted by the proposed control system.

Switched Reluctance Motors (SRMs) have superior operating characteristics compared to existing AC motors and are being considered for various applications as variable speed drive sources. However, SRM has high speed fluctuation rate because of speed-torque characteristic of direct current, which makes it difficult for variable speed operation. In this paper, we propose a method that can actively adjust the speed-torque characteristics of SRM to suit the load characteristics.

Technology-Speed Control of Switched Reluctance Motors

Conventional technology-Adjusts speed-torque during operation, not preset

SRM has high speed fluctuation rate because of speed-torque characteristic of DC series. In this proposal, the speed-torque characteristic of SRM can be actively adjusted to the load characteristic.

Figure 1 shows the adjustment of speed-torque by adjusting voltage and dewll angle

2 is a principle of gain adjustment when matching two converters.

3 shows the speed-torque characteristic adjustment principle by converter gain adjustment.

4 shows the dynamic speed control principle (a) setting value (b) load reduction (c) load increase

5 is a change in the dwell angle with increasing load

(r) Speed reference signal (p) Rotor speed signal (d) Dwell angle signal

6 is a rotor encoder

7 shows speed-torque adjustment by converter conversion gain adjustment.

8 is a control system for torque-speed adjustment

9 is a schematic diagram of a voltage regulator

10 shows torque characteristics adjusted by the proposed control system.

In order to adjust the speed-torque characteristic, the speed feedback loop of the motor with respect to the reference speed is constructed. At this time, the speed detection of the motor is detected as a pulse signal by a simple disc encoder, and at the same time, the reference speed is also pulsed. At this time, the motor speed is DC to the F _M / V converter and the reference speed is formed to the V / F _R converter, but the F _M / V and V / F _R converter adjust the conversion gain as shown in Fig. 2 to adjust the frequency / voltage. Combine with different conversion constants.

Thus, by adjusting the bias voltages of both F / V converters, the swinging frequency and speed of the SRM can be adjusted as shown in FIG. 3.

Switched Reluctance Motors (SRMs) have superior operating characteristics compared to existing AC motors and are being considered for various applications as variable speed drive sources. However, SRM has high speed fluctuation rate due to the DC-torque characteristic of speed-torque, and it is difficult for variable speed operation. In this proposal, we propose a method that can actively adjust the speed-torque characteristic of SRM to fit the load characteristics to improve the motor torque utilization rate.

Claims (1)

A method in which the speed-torque characteristic of SRM can be actively adjusted to match the load characteristic. The voltage equation of SRM is shown in equation (1). In order to adjust the speed-torque characteristic, the speed feedback loop of the motor with respect to the reference speed is constructed. At this time, the speed detection of the motor is detected as a pulse signal by a simple disc encoder, and at the same time, the reference speed is also pulsed. At this time, the motor speed is DC to the F _M / V converter, the reference speed is formed by the V / F _R converter, as shown in Figure 2 F _M / V and V / F _R converter by adjusting the conversion gain frequency / voltage Combine with different conversion constants. Now, the conversion equation for the F _M / V and V / F _R converters is Therefore, when these are combined, they are identified under the following frequency conditions. Thus, it is possible to adjust the switching frequency and speed of the SRM by adjusting the bias voltage of both F / V converters. here Is the conversion constant of V / F _R and F _M / V And Is their bias voltage. The speed-torque characteristic in SRM is controlled by the magnitude of the current of the excitation electromotive force. And the magnitude of the current is controlled by the advance angle. In the synchronizer, when the load torque is increased or decreased, the phase difference angle is increased and the torque output corresponding to its sine value is responded quickly. Torque control in this proposal introduces this principle, and if load torque is increased or decreased in SRM, the dwell angle of current is increased and decreased without additional computing device, and at the same time, it has effective torque output proportional to the square of instantaneous current to improve the dynamic characteristics of the motor. Made it possible. The speed-torque adjustment operation is operated in the same manner as in FIG. 2 in a speed controller composed of an F _M / V and a V / F _R converter. When the two converters match, the average value of the load current is the compensation to the reference model for the impedance drop component in the voltage equation of equation (1). The bias value is adjusted by returning the conversion value to the reference value F _M / V. Equation (3) has a relational expression as in Equation (4) below. here Is the motor speed frequency with the system identified, Is the load current Feedback coefficient, Is the feedback compensation coefficient of dwell angle θ _DW . Where the feedback constant of the load current, And the feedback coefficient of the power (dwell) angle, If the drive system for adjusting the configuration is configured as shown in FIG.