Doubly Salient Permanent Magnet Research Articles

New Methods of Measuring Inductance of Doubly Salient Permanent Magnet Motors

The inductance characteristic of doubly salient permanent magnet (DSPM) motors is the basis of design, analysis, and control of the motor. Due to the nonlinearity and doubly salient structure of the motor, this characteristic is a function of not only the rotor position, but also the strengthening and weakening actions of the armature flux to the permanent magnet (PM) flux, which makes the measurement of inductance difficult. This article proposes new methods for the measurement of the motor inductance for any rotor positions and level of excitation. The methods are applied to the two newly proposed DSPM motors and the results are compared with those obtained by finite element analysis. It is shown that the proposed peak value method can correctly reflect the influence of the strengthening and weakening actions of the armature flux to the PM flux on the inductance of DSPM motors.

Analysis and control of novel split-winding doubly salient permanent magnet motor for adjustable speed drive

In this paper, a novel split-winding doubly salient permanent magnet (DSPM) motor is proposed and the theoretical and experimental studies on the magnetic field, static characteristics and control strategy of this motor are carried out. The steady-state and dynamic models are presented and the output power equation is derived. The feasibility of extending the operation range of the DSPM motor by using split-windings is proved. The finite element method is used to analyze the magnetic field, in which the leakage flux outside the stator circumference is taken into account. Based on the operation principle and the static characteristics of the motor, the control strategy and scheme are developed and implemented in a microcomputer-based controller. According to the features of the 4-phase 8/6-pole DSPM motor, a half-bridge power converter without neutral is adopted to reduce the number of power devices and to eliminate the problem of voltage unbalance in the split capacitors. The experimental results on the prototype machine not only verify the theoretical analysis, but also show that the proposed DSPM motor drive possesses good steady-state and dynamic performances, offering high efficiency over wide power range, and that the split-winding topology can effectively extend the operation range of the DSPM motor.

Design and analysis of a new doubly salient permanent magnet motor

This paper presents the design and analysis of a new doubly salient permanent magnet (DSPM) motor. The corresponding output power equation is analytically derived. The initial calculation of motor dimensions and parameters, namely, the core diameter, stack length, permanent magnet size, and winding turns, are also discussed. An 8/6-pole DSPM motor is designed and built for exemplification. Moreover, finite element analysis of this motor is carried out to investigate the magnetic field distribution at different rotor positions and load currents, in which the leakage flux outside the stator circumference of the DSPM motor is firstly taken into account. Hence, the characteristics of the proposed motor are deduced. Experimental results of the prototype are given to verify the theoretical analysis and to confirm its high efficiency.

Static characteristics of a new doubly salient permanent magnet motor

In this paper, magnetic field analysis of a new doubly salient permanent magnet (DSPM) motor is carried out based on the finite element method (FEM). Hence, the corresponding static characteristics, including PM flux linkage, self-inductance, mutual inductance, and static torque are deduced (the interaction between the PM field and armature field are taken into account). New methods for measuring the motor inductance are also proposed. The theoretical analysis is verified by experimental results.

Static Characteristics of a New Doubly Salient Permanent Magnet Motor

In this paper, magnetic field analysis of a new doubly salient permanent magnet (DSPM) motor is carried out based on finite element method (FEM). Hence, the corresponding static characteristics including PM flux linkage, self-inductance, mutual inductance, and static torque-are deduced (the interaction between the PM field and armature field are taken into account). New methods for measuring the motor inductance are also proposed. The theoretical analysis is verified by experimental results.

Performance Analysis of Split-Winding Doubly Salient Permanent Magnet Motor for Wide Speed Operation

In this paper, various flux-weakening techniques available for wide speed operation of the doubly salient permanent magnet (DSPM) motor are reviewed. A new split-winding topology capable of widening the speed range is proposed, which is valid not only for the DSPM motor with stationary PMs, but also for that with rotary PMs. Based on the parameters obtained by finite element analysis, the performance of the proposed DSPM motor is analyzed. The results show that this motor combines the features of wide speed range, high efficiency, simple structure, and low cost.

Nonlinear varying-network magnetic circuit analysis for doubly salient permanent-magnet motors

In this paper, a nonlinear varying-network magnetic circuit (VNMC) modeling method is developed for doubly salient permanent-magnet (DSPM) motors. The method is used to analyze the static characteristics of DSPM motors by specific performance calculations, in which the interaction between the permanent-magnet field and the armature current field, as well as magnetic saturation, are taken into account. Two newly proposed DSPM motors (12/8-pole and 6/4-pole) are used as examples. There is good agreement between the results of the nonlinear VMMC modeling method and finite-element analysis. Moreover, the nonlinear VNMC method offers the advantage of calculating, effectively and efficiently, the static characteristics of DSPM motors having different dimensions, parameters, and conditions. Finally, the proposed method is verified by experimental testing of a 6/4-pole prototype.

Performance Analysis of 8/6-Pole Doubly Salient Permanent Magnet Motor

In this paper, a new 8/6-pole doubly salient permanent magnet (DSPM) motor is proposed and analyzed. The key is to analytically derive the output power density of the DSPM motor in terms of the rotor-to-stator pole ratio. Hence, the analytical design, finite element analysis, and computer simulation of the proposed 8/6-pole DSPM motor are presented. Compared with the well-known 6/4-pole DSPM motor, the proposed 8/6-pole offers higher power density, wider speed range, less torque ripple, and less phase current magnitude.

A general approach to sizing and power density equations for comparison of electrical machines

Whenever an electrical machine is meant to be fed by a power converter, the design should be approached as a system optimization, more than a simple machine sizing. A great variety of electrical machines is available to accomplish this goal, and the task of comparing the different options can be very difficult. A general purpose sizing equation, easily adjustable for every topology, that could take into account different waveforms and machine characteristics, would be a very desirable tool. In this paper, a general approach is presented to develop and to discuss such an equation. Sample applications of the sizing and power density equations are utilized to compare the induction machine and the doubly salient permanent magnet (DSPM) machine.

Evolution of generalized sizing for evaluation of converter fed machines

Based on the concept of the converter fed machines (CFMs), an optimal machine design can be considered as the best match of the machine topology, the power electronic converter and the performance specifications. To evaluate power production potentials of machines with various topologies with different waveforms of back emf and current, the generalized sizing equations and the power density equation are needed to evaluate the main dimensions and the power of such machines. In this paper, a general approach is presented to develop and to discuss these equations. Sample applications of the generalized sizing and power density equations are utilized to evaluate the induction machine and the double-salient permanent magnet (DSPM) machine.

A NEW DOUBLY SALIENT PERMANENT MAGNET MOTOR FOR ADJUSTABLE SPEED DRIVES

ABSTRACT A new type of doubly salient motor is presented in this paper in which the field excitation is provided by permanent magnets. This doubly salient Permanent Magnet (DSPM) motor is shown to be kindred to square waveform permanet magnet brushless dc (PM-BLDC) motors in principle. However, they are different from the latter in that they are capable of a considerable constant power range when properly designed. Finite Element Analysis and Transient Simulation studies are utilized to investigate the characteristics of this new type of PM motor. A prototype DSPM motor is designed and comparison is made between this new type of motor and other types of motor on the basis of performance of the entire drive. By fully exploiting the merits of modern high energy PM material and the doubly salient structure, the DSPM motor can offer higher performance expectation over many existing motors in terms of efficiency, torque density, torque-to-current ratio, torque-to-inertia ratio etc. with a relatively simple str...