M.S. Arefeen

A method for dynamic simulation of air-gap eccentricity in induction machines

In this paper, a method is proposed which enables the simulation of the air-gap eccentricity in induction machines. The method is based on the coupled magnetic circuit approach. The model is derived by means of winding functions, and no symmetry in windings layout is assumed. The parameters of the model are calculated directly from the geometry and winding layout of the machine. The effect of eccentricity is included in calculation of machine inductances. It is shown that by proper modeling of the induction motor it is possible to determine the effect of eccentricity on the machine startup, whether the machine is running off a sinusoidal supply or a converter. Theoretical foundations of the technique, as well as the detailed differential equations describing the machine performance under rotor eccentricity are presented.

Rotor time constant updating scheme for a rotor flux oriented induction motor drive

This paper presents a simple online rotor time constant identification scheme of an indirect field-oriented induction motor for the purpose of improving the performance and robustness of the drive. The proposed technique neither requires any special test signal nor any complex computations. This scheme is based on a special switching technique of the current-regulated pulsewidth modulation (CRPWM) voltage-source inverter (VSI), which allows measuring the induced voltage across the stator phase. The rotor time constant is then identified directly from this measured voltage. This proposed technique provides six windows within one electric cycle to update the rotor time constant, which should be sufficient for all practical purposes. Simulated results followed by experiments are presented to validate the effectiveness of the proposed technique.

Sensorless position measurement in synchronous reluctance motor

A new discrete position sensor elimination technique for a sinusoidally wound synchronous reluctance motor drive is presented. The proposed technique determines the rotor position at zero crossing of the phase currents. The rotor position between the zero crossings is determined by applying extrapolation. The proposed technique works well at all speeds, including zero speed. This technique can be used in both vector controlled and conventional constant volts/Hertz type of motor controllers. >

Computer-aided design and application of integrated LC filters

In this paper, methods of design and application of an integrated inductor-capacitor-transformer (LCT) are presented. A generalized modeling approach is also described. On the basis of this model and by using practical data, CAD software is developed for LCT, Several integrated LC and LCT samples were designed, built, and tested. Finally, a resonant power converter, using the integrated LCT, was built and tested.

Self-tuning control of switched reluctance motors for optimized torque per ampere at all operating points

Online self-tuning of control angles of a switched reluctance motor (SRM) is essential to optimize its performance in the presence of manufacturing imperfections. This paper reports an adaptive control scheme to optimize the torque per ampere at low and high speeds using artificial neural networks (ANN). An heuristic optimization technique has been introduced to find the changes in control angles. Using these results, the ANN will update its synaptic weights. Computer simulation has been employed to show the feasibility of this approach. Experimental results are provided to demonstrate the working of the self-tuning control.

Controlling multiple motors utilizing a single DSP controller

Traditionally the cost sensitive motor drive market forced designers to avoid DSP controllers for their drive design. However, several factors are rapidly changing this scenario. The prices of DSPs have dropped from hundreds of dollars to approximately three dollars since their introduction in the early 1980s. Moreover, DSPs can now integrate a variety of sophisticated peripherals. This integration of DSP core with a set of useful peripherals significantly simplifies the design. At the same time, the cost sensitive drives like heating ventilating and air conditioning (HVAC), appliances are starting to utilize variable speed drives to maximize the efficiency and comfort for the user. Many of these applications have more than one motor. For example, a typical HVAC system usually utilizes two motors. Until now, these motors were mainly operated at a fixed speed or at a set number of multiple speeds to minimize cost. This paper shows the advantages of using DSP controllers for such applications. It will be shown that these controllers provide a true single chip solution for these drives.

An analysis of the accuracy of indirect shaft sensor for synchronous reluctance motor

The authors report a rotor position sensing technique for the SynRM (synchronous reluctance motor) which does not use any discrete position sensors. An accuracy analysis of the new indirect SynRM position sensing scheme is presented. The analysis breaks down the position error to the fundamental causes in the position sensing scheme. The individual sample error at the phase current zero crossings comes from the quantization error of the induced voltage and the quantization and the sampling rate errors of the phase current. It is shown that the present rotor sensor is adequate for <or=1 degrees accuracy in rotor position sensing during the extended zero crossing periods of the phase currents.<<ETX>>

Elimination of discrete position sensor for synchronous reluctance motor

A new discrete position sensor elimination technique for a sinusoidally wound synchronous reluctance motor drive is presented. The proposed technique determines the rotor position at zero crossing of the phase currents. The rotor position between the zero crossings is determined by applying extrapolation. The proposed technique works well at all speeds, including zero speed. This technique can be used in both vector controlled and conventional constant volts/hertz motor controllers.<<ETX>>

Indirect startup rotor position sensor for synchronous reluctance motor

This paper presents a new indirect method of sensing the rotor positions in a synchronous reluctance motor at zero speed. The method is based on a special diagnostic switching control of the drive converter. The induced phase voltages and currents from this diagnostic signal is used to determine the position of the rotor. Variations of the method also work accurately and with robustness at all speeds. This method requires no additional hardware, other than the drive circuitry and microcontroller. The theoretical foundations of the method are presented and the experimental results are shown to verify the practicality of the method.<<ETX>>