EPE Association: EPE 1991 - 34 - Session 4.1: SWITCHED AND VARIABLE RELUCTANCE MOTOR DRIVES

EPE 1991 - 34 - Session 4.1: SWITCHED AND VARIABLE RELUCTANCE MOTOR DRIVES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1991 - Conference > EPE 1991 - 34 - Session 4.1: SWITCHED AND VARIABLE RELUCTANCE MOTOR DRIVES

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   DESIGN AND CONTROL OF LOW POWER SWITCHED RELUCTANCE MOTORS (< 1 kW)
By A. Weller; P. Trawinski [View]
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Abstract: Simple formulas are given to calculate all interesting parameters for 6/4 switched reluctance (SR) motors. These formulas are intended for a quick overview of the torque capabilities and efficiencies of a motor and they can be used to estimate the VA requirements of the control electronics. We further make a comparison of different control strategies and propose a firing angle control which relies on a linear relationship between firing angle and motor speed. In combination with a closed-loop control of the phase currents this results in a wide speed range of the motor with high torque capability and good efficiency. The sources of noise in SR motors and ways to reduce them are discussed.

   SWITCHED RELUCTANCE DRIVES USING BRUSHLESS DC MOTOR CONTROLLER
By M. Crivii; M. Jufer; T. Reinman [View]
[Download]

Abstract: The switched reluctance motor, characterized by the simplicity of its rotor structure, depends directly on the performances of the position sensor, on the control and on the drive which is associated. It is possible to find different driver solutions, integrated, for the brushless DC motor. The present paper describes the posibility to achieve the Motorola controller MC33035 to drive a low-power switched reluctance motor.

   A TORQUE ANGLE CALCULATOR FOR SENSORLESS RELUCTANCE MOTOR DRIVES
By Silverio Bolognani [View]
[Download]

Abstract: A simple technique for calculating the torque angle in reluctance synchronous motors by measuring terminal quantities is presented. The paper begins by deriving the calculation formula from the general dynamic equations of a reluctance motor. Limits due to parameter sensitivity are then discussed. An experimental validation of the proposed torque angle calculator applied to a current fed-reluctance motor is also included. When incorporated in a suitable control scheme, the torque angle calculator allows motor drives without any position and speed transducers to be built up, as illustrated in the paper.

   An Auxiliary Quasi-Resonant DC Link lnverter for Switched Reluctance Machines
By R. W. De Doncker; J. P. Lyons [View]
[Download]

Abstract: Conventional SRM inverters are hard-switched resulting in significant power device stresses during switching events, high levels of electromagnetic interference, and efficiency reduction due to power device switching losses. This paper introduces a quasi-resonant dc link power electronic circuit topology and gating control strategy which insures soft switching of an SRM inverter. Soft switching enables substantially higher (ultrasonic) switching frequencies with reduced device stresses. The proposed circuit utilizes an auxiliary resonant commutated pole (ARCP) to create the quasi-resonant dc link. The LC resonant circuit can be triggered, on demand, by auxiliary power electronic switches to create a zero-voltage soft-switching opportunity for the inverter switches, thereby ensuring near lossless switching.

   PWM-Based Position Sensorless Control of Variable Reluctance Motor Drives
By Michael G. Egan; Michael B. Harrington; John M.D. Murphy [View]
[Download]

Abstract: The switched or variable reluctance machine offers many advantages for variable speed drive applications. However, the requirement of switched reluctance drives for a shaft position sensor can be a significant disadvantage relative to inverter-fed induction motor drive systems. One solution which has been investigated is to utilise the angle-dependent phase inductance profile of the reluctance machine to derive position information and thereby achieve self-synchronous, or position-sensorless, operation of the drive. Difficulties arise however due to the influence of ohmic losses, magnetic losses, converter voltage ripple, mutual inductance effects and switching noise. This paper presents a new solution to the problem based upon the combined techniques of pulsewidth modulated (PWM) control and synchronous demodulation. In a constant-frequency PWM system, the phase current ripple is amplitude modulated by the inductance profile of the machine. The new technique employs synchronous demodulation to extract the reactive component of current at the PWM frequency from the total motor phase current. The amplitude of this component is a direct measure of the angle dependent phase inductance. The strategy which is described results in an accurate, on-line continuous reproduction of the machine inductance profile which is essentially independent of magnetic losses, mutuaI inductance, inverter link voltage and motor speed. The demodulated signal is ultimately processed by a multi-mode microcontroller-based system to give the position and velocity information required to implement torque and closed-loop speed control of the self-synchronous drive.

   PM AND VR BRUSHLESS MOTORS FEED FOR PEAK-TORQUE OPERATIONS
By E. Pagano; A. Perfetto [View]
[Download]

Abstract: The paper deals wilh two different typologies of brushless motors: permanent magnet (PM) and variable reluctance (VR). On tbe basis of the generalized theory of functions, an electromagnetic torque expression is proposed that is useful for both brushless motors. The analysis of the armature currents versus rotor position laws, that gives rise to maxima possible values of the electromagnetic torque, is performed. A second part of the paper is devoted to the comparative analysis of power electromagnetic converting capability of both PM and VR structures. The analysis is devoted to the evaluation of the weight of the air-gap variable reluctance on the electromagnetic torque developed for given boundary values of the airgap flux density and of the armature current.

EPE 1991 - 34 - Session 4.1: SWITCHED AND VARIABLE RELUCTANCE MOTOR DRIVES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1991 - Conference > EPE 1991 - 34 - Session 4.1: SWITCHED AND VARIABLE RELUCTANCE MOTOR DRIVES
	[return to parent folder]

	DESIGN AND CONTROL OF LOW POWER SWITCHED RELUCTANCE MOTORS (< 1 kW) By A. Weller; P. Trawinski	[View] [Download]
Abstract: Simple formulas are given to calculate all interesting parameters for 6/4 switched reluctance (SR) motors. These formulas are intended for a quick overview of the torque capabilities and efficiencies of a motor and they can be used to estimate the VA requirements of the control electronics. We further make a comparison of different control strategies and propose a firing angle control which relies on a linear relationship between firing angle and motor speed. In combination with a closed-loop control of the phase currents this results in a wide speed range of the motor with high torque capability and good efficiency. The sources of noise in SR motors and ways to reduce them are discussed.

	SWITCHED RELUCTANCE DRIVES USING BRUSHLESS DC MOTOR CONTROLLER By M. Crivii; M. Jufer; T. Reinman	[View] [Download]
Abstract: The switched reluctance motor, characterized by the simplicity of its rotor structure, depends directly on the performances of the position sensor, on the control and on the drive which is associated. It is possible to find different driver solutions, integrated, for the brushless DC motor. The present paper describes the posibility to achieve the Motorola controller MC33035 to drive a low-power switched reluctance motor.

	A TORQUE ANGLE CALCULATOR FOR SENSORLESS RELUCTANCE MOTOR DRIVES By Silverio Bolognani	[View] [Download]
Abstract: A simple technique for calculating the torque angle in reluctance synchronous motors by measuring terminal quantities is presented. The paper begins by deriving the calculation formula from the general dynamic equations of a reluctance motor. Limits due to parameter sensitivity are then discussed. An experimental validation of the proposed torque angle calculator applied to a current fed-reluctance motor is also included. When incorporated in a suitable control scheme, the torque angle calculator allows motor drives without any position and speed transducers to be built up, as illustrated in the paper.

	An Auxiliary Quasi-Resonant DC Link lnverter for Switched Reluctance Machines By R. W. De Doncker; J. P. Lyons	[View] [Download]
Abstract: Conventional SRM inverters are hard-switched resulting in significant power device stresses during switching events, high levels of electromagnetic interference, and efficiency reduction due to power device switching losses. This paper introduces a quasi-resonant dc link power electronic circuit topology and gating control strategy which insures soft switching of an SRM inverter. Soft switching enables substantially higher (ultrasonic) switching frequencies with reduced device stresses. The proposed circuit utilizes an auxiliary resonant commutated pole (ARCP) to create the quasi-resonant dc link. The LC resonant circuit can be triggered, on demand, by auxiliary power electronic switches to create a zero-voltage soft-switching opportunity for the inverter switches, thereby ensuring near lossless switching.

	PWM-Based Position Sensorless Control of Variable Reluctance Motor Drives By Michael G. Egan; Michael B. Harrington; John M.D. Murphy	[View] [Download]
Abstract: The switched or variable reluctance machine offers many advantages for variable speed drive applications. However, the requirement of switched reluctance drives for a shaft position sensor can be a significant disadvantage relative to inverter-fed induction motor drive systems. One solution which has been investigated is to utilise the angle-dependent phase inductance profile of the reluctance machine to derive position information and thereby achieve self-synchronous, or position-sensorless, operation of the drive. Difficulties arise however due to the influence of ohmic losses, magnetic losses, converter voltage ripple, mutual inductance effects and switching noise. This paper presents a new solution to the problem based upon the combined techniques of pulsewidth modulated (PWM) control and synchronous demodulation. In a constant-frequency PWM system, the phase current ripple is amplitude modulated by the inductance profile of the machine. The new technique employs synchronous demodulation to extract the reactive component of current at the PWM frequency from the total motor phase current. The amplitude of this component is a direct measure of the angle dependent phase inductance. The strategy which is described results in an accurate, on-line continuous reproduction of the machine inductance profile which is essentially independent of magnetic losses, mutuaI inductance, inverter link voltage and motor speed. The demodulated signal is ultimately processed by a multi-mode microcontroller-based system to give the position and velocity information required to implement torque and closed-loop speed control of the self-synchronous drive.

	PM AND VR BRUSHLESS MOTORS FEED FOR PEAK-TORQUE OPERATIONS By E. Pagano; A. Perfetto	[View] [Download]
Abstract: The paper deals wilh two different typologies of brushless motors: permanent magnet (PM) and variable reluctance (VR). On tbe basis of the generalized theory of functions, an electromagnetic torque expression is proposed that is useful for both brushless motors. The analysis of the armature currents versus rotor position laws, that gives rise to maxima possible values of the electromagnetic torque, is performed. A second part of the paper is devoted to the comparative analysis of power electromagnetic converting capability of both PM and VR structures. The analysis is devoted to the evaluation of the weight of the air-gap variable reluctance on the electromagnetic torque developed for given boundary values of the airgap flux density and of the armature current.