Hybrid Switch Reluctance Drives For Pump Applications

Uffe Jakobsen

Research output: Book/ReportPh.D. thesis

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The initial research problem is to investigate an alternative motor drive to the existing permanent magnet synchronous and brushless DC-motor drives for pump applications. A review of different motor types showed that a possible candidate for another low cost permanent magnet motor may be the single phase hybrid switched reluctance motor (HSRM). Due to the simple construction of the single phase HSRM, manufacturing may be simplified compared to a three phase permanent magnet motor and consumption of copper may be lowered when compared to both the induction motor and some three phase permanent magnet motors.

The focus of this thesis is regarding the design and control of a single phase hybrid switched reluctance motor (HSRM) intended to drive e.g. a centrifugal pump. A single phase hybrid switched reluctance motor was designed with a novel stator pole shaping method and a new arrangement of permanent magnets for flux concentration was presented. It was shown how stator pole shaping can improve starting torque for a single phase hybrid switched reluctance motor. It was demonstrated that the configuration of permanent magnets in different flux concentration arrangements influences the shape and magnitude of the torque. This first prototype is used for most of the experiments presented in the thesis. The motor achieves an efficiency of close to 77% at an output power of 72 W, comparable to a BLDC or PMSM in a similar power range.

An alternative speed control method suitable for control of motor drives with a high periodic torque ripple is used to control the HSRM. The torque of a single phase HSRM has a nonlinear dependency on both current and the angle, where active torque control is not possible for the entire stroke. The torque produced has a periodic ripple, with a period of four times the rotational frequency, which is also giving a periodic ripple in the speed. This speed ripple may affect the input to a time invariant speed controller if it is not low pass filtered. If the speed
controller updates are also not synchronized with the strokes, the speed controller outputs may change during a stroke. The changes of speed controller output during a stroke, may give rise to undesired low frequency oscillations in the speed controller output. A time variant speed controller is presented in the thesis that does not suffer from these issues.

Like the brushless DC-motor (BLDC) and the permanent magnet synchronous motor (PMSM), the HSRM needs information about rotor position to be properly controlled. For BLDC, PMSM, induction motors, and the normal SRM position sensorless methods are relatively well established and have been used for some time. For the single phase switched reluctance motor several methods have been used, however for the single phase hybrid switched reluctance motor there seems to be no known methods. The presented position sensorless method is simple, robust towards parameter changes and thus suitable for implementation in a mass produced low cost drive.

A method to protect windings in a HSRM, flooded with boiling water, is also presented but has yet to be tested for its lifetime performance.
Original languageEnglish
PublisherDepartment of Energy Technology, Aalborg University
Number of pages241
ISBN (Print)978-87-92846-01-3
Publication statusPublished - 2011


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