A new polygonal-winding permanent magnet brushless DC motor drive for electric vehicles
Of thesis entitled:
A New Polygonal-Winding Permanent Magnet Brushless DC Motor Drive for Electric Vehicles
Submitted by Yong Wang
for the Degree of Doctor of Philosophy at The University of Hong Kong
' in October 2004
The electric motor drive system is one of the key parts in Electric Vehicles (EV). The permanent magnet (PM) brushless DC (BLDC) motor drive has a potentially very attractive EV application, as it has the distinct advantages of high efficiency and high power density. But it has difficulties in extending its speed range due to its uncontrollable PM flux.
In this study, a new polygonal winding PM BLDC motor drive with a special hybrid rotor structure and polygonal stator winding connection is proposed, designed to extend motor speed range via a novel motor topology rather than a complicated control strategy. The design of the new PM BLDC motor is based on EV aerodynamic analysis. The analysis is made according to the requirements of a specific driving profile, and the EV requirements for its drive motor can be obtained from those analysis results. The new PM BLDC motor has a hybrid rotor and a polygonal connected stator winding. The hybrid rotor structure combines elements of a PM BLDC motor and a Switched Reluctance (SR) motor. The performance of the hybrid rotor is compared with that of a classical PM rotor, and its advantages are displayed. .
A novel polygonal winding connection enables the motor to extend its speed range without the need for complex control strategies. The polygonal winding connection also gives the motor a multiple torque-speed, which can further extend the motor speed. The finite element method (FEM) is employed in the analysis of the new PM BLDC motor, and both the static and transient fields are analyzed. The motor operation is simulated via circuit-torque-field coupled time stepping FEM analysis. The novelty of the analysis is that it can simulate not only the standard motor operation mode but also the flux-weakening operation mode.
The simulations and experimental results demonstrate that the new PM BLDC motor drive offers high efficiency, high power density and a wide speed range, which make it very suitable for EV application.
School:The University of Hong Kong
School Location:China - Hong Kong SAR
Source Type:Master's Thesis
Keywords:permanent magnet motors electric vehicles
Date of Publication:01/01/2005