The control of Brushless Permanent Magnet Motors require rotor position information that can be measured by means of a position sensor. The motion sensorless control aims at eliminating the motor position sensor and its corresponding electronic conditioning circuits, cabling and connectors. Besides a clear cost reduction, the motion sensorless drives have better reliability when compared with their position sensor-based counterparts. The research conducted in the last two decades has provided many different solutions that are used in many applications. Nevertheless, the literature reports just a few survey papers dealing with this important topic. This paper intends providing a comprehensive review of the sensorless control solutions, including the machine influence on the sensorless drive performance.

Sensorless control of PM motor drives — A technology status review

This paper describes problems of the sensorless starting of horizontal axis washing machines with direct drive and proposes solution, which was experimentally verified. H-axis washing machines have very difficult conditions for the drive starting, especially at full load. Inertia of the tub and water, torque from the laundry make load torque at starting higher than rated one and sometimes even higher than the maximum torque of the motor, which makes sensorless starting extremely challenging task. This paper suggests modified open-loop starting, where control system is closed shortly after beginning at low speed and rotates the drum until laundry restructuring. To ensure proper work of the sensorless algorithm at low speed an additional method for the drive parameters estimation has been proposed and verified by the experimental results.

Sensorless starting of horizontal axis washing machines with direct drive

Improving the performance of Switched Reluctance Motors (SRMs) such that they become a viable alternative to PM motors has been an active area of investigation. In this paper, a low voltage, high power, double-stator SRM (DSSRM) is proposed for washing machine application. First, an appropriate configuration for the motor structure is introduced and theoretically designed to be used in this application. Second, the electromagnetic characteristics of the proposed configuration are analyzed with the finite element method (FEM) in order to predict the motor's performance. Finally, a prototype of the motor is built and experimentally tested to verify the theoretical and simulation analysis, also confirm its applicability.

A 12/8 double-stator switched reluctance motor for washing machine application

This paper describes problems of the sensorless starting of horizontal axis washing machines with direct drive and suggests solution, which was experimentally verified. Horizontal axis washing machines have very difficult conditions for the drive starting, especially at full load. Inertia of the tub and water, torque from the laundry make load torque at starting higher than rated one and sometimes even higher than the maximum torque of the motor, which makes sensorless starting extremely challenging task. This paper suggests modified open-loop starting, where control system is closed shortly after beginning at low speed and rotates the drum until laundry restructuring. To ensure proper work of the sensorless algorithm at low speed additional measures for increasing of the estimation algorithm performance have been taken. These measures include special algorithm for the drive parameters estimation, which has been developed and verified by the experimental results.

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Sensorless Starting of Direct Drive Horizontal Axis Washing Machines

Reducing motor losses is very important in connection with raising the requirements set by international regulations on reducing electricity consumption. As induction motors are increasingly powered by high-frequency voltage, core losses starting to play a dominant role in motor loss balance. The presented paper shows how to calculate the basic and additional losses in the core of the induction motor, generated by the reluctance and slot harmonics of the magnetic field in the motor and by the higher harmonics produced by the inverter, using analytical and field-circuit methods. The results for motor operation at frequencies of supply voltage 10, 20 and 350 Hz were presented and compared with the results of measurements. The main achievement is the statement that losses in the core of the motor fed from the inverter should be calculated as the sum of losses generated by individual harmonics both in the motor and generated by the inverter.

Core losses of the induction motor operating in a wide frequency range supplied from the inverter

The paper deals with a Direct Flux and Torque Control (DFTC) scheme for motion sensorless Direct Drive (DD) washing machine applications employing Surface Mount (SM) Permanent Magnet (PM) motors. This solution provides very good performance under current and voltage limitations and represents a viable alternative for washing machine applications. Complete experimental results, obtained on a DD washer prototype, are presented to demonstrate the feasibility of the proposed solution.

Sensorless Direct Flux and Torque Control for Direct Drive washing machine applications

In ship field, to ensure reliable operation of three-phase electric motor, two redundant input power supplies are generally equipped, one works as main power and the other as hot redundancy. When the main power fails, the input power of the motor should smoothly transfer to the standby power. During the transfer process, a comparatively large phase difference between the electromotive force and the standby power supply will cause large surge current far exceeding the direct start-up current of the motor, which will severely damage the motor and shorten its lifetime, so is the case when switching back after troubleshooting. In this paper, a novel transfer switch is proposed with its control strategies detailedly illustrated. This switch could limit the voltage difference within the rated voltage of the motor and meanwhile limit the phase difference within 60°, so the surge current won’t exceed the direct start-up current of the three-phase asynchronous machine. Its effectiveness is verified by experiments carried out on a 10kVA prototype.

B. He

Papers

Sensorless Direct Flux and Torque Control for Direct Drive washing machine applications

A Novel Transfer Switch and Control Strategy for Dual Input Power Supplies of Three-phase Electric Motor