Optimum Commutation Research Articles

Reduction of Torque Ripple in Switched Reluctance Motor Drives Through Optimum Commutation Angles Control

Reduction of Torque Ripple in Switched Reluctance Motor Drives Through Optimum Commutation Angles Control

A Novel Multi-Criteria Local Latin Hypercube Refinement System for Commutation Angle Improvement in IPMSMs

The commutation angle, γ, of an interior permanent magnet synchronous motor's (IPMSM) vector diagram, plays an important role in compensating the back electromotive force (back-EMF); both under phase current variations and an extended speed range, is required by the application. This commutation angle is defined as the angle between the fundamental of the motor phase current and the fundamental of the back-EMF. It can be utilised to provide a compensating effect in IPMSMs. This is due to the reluctance torque component being dependent on the commutation angle of the phase current even before entering the extended speed range. A real-time maximum torque per current and voltage strategy is demonstrated to find the trajectory and optimum commutation angles, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">γ</i> , where the level of accuracy depends on the application and available computational speed. A magnet volume reduction using a novel multi-criteria local Latin hypercube refinement (MLHR) sampling system is also presented to improve the optimisation process. The proposed new technique minimises the magnet mass to motor torque density whilst maintaining a similar phase current level. A mapping of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">γ</i> allows the determination of the optimum angles, as shown in this paper. The 3 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> generation Toyota Prius IPMSM is considered as the reference motor, where the rotor configuration is altered to allow for an individual assessment.

A switched-reluctance motor for aerospace application: Design, analysis and results

This paper presents a five-phase switched reluctance motor designed to satisfy the requirements of flap actuators in medium size aircrafts, a real example of the more electric aircraft trend. In normal conditions the machine operates with two phases conducting simultaneously but it is designed to satisfy the load specifications also with one or two phases open as consequence of fault remedial strategies. A finite-element study, aiming to predict both the healthy and faulty-mode performance, is presented. The mean torque vs. current capability and the torque ripple are investigated and optimum commutation angles are evaluated in static conditions. Experimental tests on the motor prototype are included, which confirm its capability to satisfy the planned degraded modes of operation and validate the design.

Optimal Driving Efficiency Design for the Single-Phase Brushless DC Fan Motor

One of the methods to improve efficiency and torque performance of the single-phase brushless DC (BLDC) motor is to find out the optimum commutation angle at each different speed. We used the finite-element method (FEM) to simulate the back-EMF voltage and the coil current for the single-phase BLDC motor, and then adjust the conduction time of switches by detecting the waveform of coil current. The motor can improve its efficiency, noise, and vibration when it obtains the optimal shift angle of each speed. We used PSPICE to verify the exactness of FEM simulation results of the single-phase BLDC motor. We adopted Microchip's dsPIC30F4011 digital signal processor (DSP) to process the Hall signal and the driving signals of switches of the driving system prototype of the single-phase BLDC fan motor. Finally, we used the related experimental results to confirm the feasibility and effectiveness of the proposed driver.

Analysis, design, and optimization of the LCC resonant inverter as a high-intensity discharge lamp ballast

A complete study of the clamped-mode (CM) series-parallel (LCC) resonant inverter together with some of the control-to-output characteristics are presented in this paper. Also, a new control method for the CM LCC resonant inverter is introduced. With this method, the inverter is forced to operate with optimum commutations and without handling reactive energy, thus minimizing both switching and conduction losses. The corresponding design procedure is illustrated with a design example. Finally, some experimental results obtained from a prototype at the laboratory are also shown to validate the analysis and evaluate the proposed control method.

High Intensity Discharge Lamps Supplied with a Novel Low-Loss Clamped-Mode LCC Resonant Inverter

SummaryA novel clamped-mode LCC resonant inverter with very low losses is presented in this paper. Switching and conduction losses are minimised forcing the inverter to operate with optimum commutations and without handling reactive energy. Output power is controlled via switching frequency and clamped interval is self-adjusted by the resonant current to obtain optimum commutations. In this way, a very simple circuit can be used to control the inverter and the efficiency achieved is very high.

Current-impulse-displacement thyristor commutation with controlled trapped energy

The paper considers the fundamental operating principles of a number of current impulse displacement commutation techniques used in thyristor DC choppers and inverters. In each case the optimum commutation pulse is considered and the conditions for unpredictable and undesirable operation due to trapped-energy ‘runaway’ are analytically specified. A simple solution exists, preventing undesired operation, whereby the trapped energy is not fed back into the supply or dissipated in resistors. The energy is safely retained and used to optimise LC commutation-circuit values. The resultant commutation circuit has a higher current commutating ability for given LC values and can result in circuits with lower losses and shorter commutation cycle times than those circuits of conventional design.

A quasi analytical procedure for determining the optimum commutation angles of PWM converters

A method for calculating the optimum commutation times for PWM converters is proposed. The method is mainly analytical and leads to a simple, fast calculation procedure. The time behaviour of any variable, electrical or non electrical, which is considered to be the most characteristic of the behaviour of the system, can be optimized. The validity of the analytical approach is subject to some hypotheses which are often verified in practice. The computation power required by the method is so limited that, in the majority of cases, a minicomputer can be used.

Power source consisting of forced‐commutation commutatorless motor operated with optimum commutation angle

Power source consisting of forced‐commutation commutatorless motor operated with optimum commutation angle