Low power high efficiency permanent magnet synchronous motor drives are needed for better home appliances. As the price of sintered (high energy NdFeB magnets) used for the scope so far has risen spectacularly in the last two-three years, the economics of their use to such high efficiency applications is in question. The present paper is investigating in comparison NdFeB surface rotor versus Ferrite interior PM rotor motor drives in the 100W to 2000W range to see if Ferrite motors can compete in terms of initial active material cost at above 94% efficiency. FEM embedded optimal design methodologies are introduced with case studies at 120W, 500W, 1000W, 2000W, 4500rpm, 290 (380) VDC. The torque pulsations with sinusoidal current control are reduced by shaping the airgap and by two segmental skewing. Also the optimal designs have been checked for full step torque response validation in sensorless vector control for 4500rpm. The results show Ferrite motors superior in initial cost at 120W and 2000W, but about the same for 500W and 1000W, for about the same efficiency, around 94%.

This paper develops a scalar V/f control system for permanent magnet synchronous motor (PMSM) drives with two stabilizing feedback corrections: i) a voltage-vector speed correction using active power variation, in action only in transient states, and ii) a voltage amplitude correction based on unity power-factor regulation loop, employing reactive power. Motor/generator operating mode is allowed using the active power sign information. The proposed solution, inherent for sensorless control, is simple, requires reduced computation time, thus it is competitive for very-high variable speed PMSM drives like fans, pumps, micro gas-turbine generators, etc. Significant simulation results prove good performance for the proposed control structure in steady and transient states, for fast speed references and step rated load torque.

Novel or modified sensorless control methods, credited with fast dynamic response, better drive efficiency and short computation time are just a few of nowadays main concerns. Therefore, this paper aims to theoretically characterize and digitally investigate through comprehensive Matlab/Simulink simulations three different V/f control strategies, with correction loops. The proposed control methods are all characterized by the missing of the vector current control standard speed and current controllers and they all use the Maximum Torque per Ampere condition (MTPA); coordinate transformations are not necessary. The most important claims of these new control strategies are fast dynamic speed and torque response, low computation effort and the bypassing of initial rotor position problem. To prove the previous claims, a fractionary winding interior permanent magnet synchronous motor (IPMSM) 42Vdc prototype was made and its parameters were previously determined by standstill and load performance laboratory tests. Preliminary test results with proposed method three are available at this point.

This paper proposes two control methods for Interior Permanent Magnet Synchronous Motor (IPMSM) Drives. The first one is a V/f control with two stabilizing loops: one loop based on active flux balance for voltage magnitude correction and a second, based on speed error, with voltage phase correction. By this control strategy, a fast dynamic speed response, without steady state error and without speed or current regulators, for all AC machines is obtained. The second control method is a sensorless vector control strategy which also has been implemented and tested, just for comparison. Comprehensive simulations of both proposed V/f and sensorless vector control have been implemented by using a Matlab/Simulink package and a dSpace based platform has been built. Rather promising fast dynamic performance is obtained, both in simulations and in laboratory experiments for the proposed IPMSM Drive.

Field oriented (FOC) and direct torque and flux (DTFC) control of AC drives are credited with fast torque response, but, in general purpose sensorless AC drives, the on-line software and hardware control effort and their reliability may seem prohibitive for general applications or, at least for synchronous motors, a starting strategy is necessary. The present paper presents a novel class of V/f sensorless AC general drives with two stabilizing loops-one based on active flux balance and one based on speed error-that provide fast speed dynamics response without steady state error, without speed or current regulators; flux weakening conditions are built in. The exposition of principles is followed by exemplification for IMs, SPMSM, IPMSM, and DC excited SMs and by digital simulations on a PM-RSM (with weak PMs and reasonably high magnetic saliency Ld/Lq>3). Rather promising fast dynamics performance is obtained, in digital simulations for a PM-RSM case study, but more theoretical and then experimental work (which is under way) are needed to fully establish the proposed solutions as practical.