Operating Characteristics of Switched Reluctance Motor Drivers by Square Wave Voltage.

Abstract

and Tadashi Fukao, Member (Tokyo Institute of Technology) Switched reluctance motors have been studied in twenty years but the applications have been limited to special cases. One of the main reasons of these limited applications is the complicated machine model and unclear operating characteristics of switched reluctance motors. Conventional synchronous motor models are not applicable because the current waveforms of switched reluctance motors include dc component and considerable amount of harmonics. A simple analytical model and normalized characteristics of switched reluctance motors are needed to express voltage, current and torque relationships.In this paper, the inductance variations of a switched reluctance motor are represented only by a fundamental component and a constant. Terminal voltage is also approximated as sinusoidal. With these approximations, the relationships of normalized voltages, currents and output powers are derived. It was found that the power to voltage ratio can be maximized at a particular voltage phase angle 8,,. It was also shown that there is another voltage phase angle 8;, which maximizes power to current ratio. The most efficient operation of switched reluctance motors can be realized with the voltage phase angle between 8; and 8,,. These analytical results were confirmed with experimental results of a test machine rated 2.2kW at a speed of 6,000rpm. 402T. IEE Japan, No. 4, '95

An egg-shaped diagram and its discrepancies in switched reluctance machines

“…In this case, and after substituting Eqs. (8) and (9), we obtain Thus, the input power P i and apparent power S can be determined using Eqs. (10) and (11).…”

“…In this case, by approximating the anticipated inductance variation at the motor terminals using a fundamental wave L 1 and a parameter L 0 [7][8][9], and determining values of L 1 and L 0 so that the egg-shaped diagram closely matches the actual points plotted in the P i -S plane, the model of the motor was obtained and reported in Refs. 10-12. In the process of comparing measured points with an egg-shaped diagram, similar to how it is done when using any circular diagram when the least square error is used as the estimation reference, a specific circle is selected.…”

An Egg-shaped Diagram and its Discrepancies in Switched Reluctance Machines.

“…In this case, by approximating the anticipated inductance variation at the motor terminals using a fundamental wave L 1 and a parameter L 0 [7][8][9], and determining values of L 1 and L 0 so that the egg-shaped diagram closely matches the actual points plotted in the P i -S plane, the model of the motor was obtained and reported in Refs. In this case, by approximating the anticipated inductance variation at the motor terminals using a fundamental wave L 1 and a parameter L 0 [7][8][9], and determining values of L 1 and L 0 so that the egg-shaped diagram closely matches the actual points plotted in the P i -S plane, the model of the motor was obtained and reported in Refs.…”

“…By measuring the input active power P i and the apparent power S by means of applying a square waveform voltage and changing its phase angle, and plotting operating points in the P i -S plane, the authors have demonstrated the near-egg shape of the resulting plot. In this case, by approximating the anticipated inductance variation at the motor terminals using a fundamental wave L 1 and a parameter L 0 [7][8][9], and determining values of L 1 and L 0 so that the egg-shaped diagram closely matches the actual points plotted in the P i -S plane, the model of the motor was obtained and reported in Refs. 10-12. In the process of comparing measured points with an egg-shaped diagram, similar to how it is done when using any circular diagram when the least square error is used as the estimation reference, a specific circle is selected.…”