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EPE 2009 - Subtopic 12-2 - LS: 'Sensorless AC Motor Drives'
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2009 - Conference > EPE 2009 - Topic 12: 'High Performance Drives' > EPE 2009 - Subtopic 12-2 - LS: 'Sensorless AC Motor Drives'
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	An Improved DTC for Matrix Converter Drives Using Multi-Mode ISVM and Unity Input Power Factor Correction   By DAN XIAO, MUHAMMED RAHMAN	[View]   [Download]
Abstract: This paper presents an improved direct torque control (DTC) method for sensorless matrix converter drives using a multi-mode indirect space vector modulation (ISVM) and an adaptive sliding mode observer. The drive system is characterized by reduced torque and flux ripples, unity input power factor, sinusoidal input/output waveforms and good sensorless control performance over a wide speed range, while maintaining constant switching frequency and fast dynamic. Independent control of both torque and flux is achieved by two PI controllers. To preserve the DTC transient merits, the ISVM is switched to an overmodulation mode when the reference voltage exceeds the saturation point of PI controllers. When the voltage reference is lower than 30\% of the allowable value, the modified input current vector modulation, utilizing medium line-to-line voltages, is employed to improve the steady-state performance at low speeds.
	Robustness Evaluation of Deadbeat, Direct Torque and Flux Control for Induction Machine Drives   By Björn HEINBOKEL, ROBERT D. LORENZ	[View]   [Download]
Abstract: Field oriented control methodologies are one of the dominant industry standards for induction machine drives. While this classical approach has continuously improved, direct torque control (DTC) has emerged as an alternative approach. Deadbeat, direct torque and flux control (DB-DTFC) is a more recent scheme and employs a discrete-time model inversion to achieve decoupled control of both torque and flux with a one PWM period response time. From z-transform-based deadbeat control design theory, it is known that incorrectly estimated system parameters can lead to forced oscillations. Therefore, it was the goal of this research to rigorously evaluate the robustness of DB-DTFC and to investigate if its advantageous properties are maintained under perturbed operating conditions. An indepth analysis first isolates the observer’s influence from the control law’s sensitivity to detuned parameters at critical operating points. An enhanced flux estimation accuracy model is derived and analyzed numerically. Then, sets of a comprehensive collection of experiments are used to evaluate DB-DTFC’s robustness in comparison to the de facto standard of indirect field oriented control. It is shown that the main contributor to decreased robustness is the flux estimation algorithm – not the DBDTFC controller itself. The experimental results demonstrate nearly ideal deadbeat control performance and a high level of robustness compared to other control methodologies.
	Torque Control Scheme for PMSM in Overmodulation Range   By Smith LERDUDOMSAK, Shinji DOKI, Shigeru OKUMA	[View]   [Download]
Abstract: In this paper, torque control scheme for PMSM when an inverter operates in the overmodulation range is proposed and examined. The torque control system has our proposed closed-loop current control system, which harmonic current compensation scheme is used to improve the stability in the overmodulation range. Finally, the overall torque control performance will be evaluated by the experimental results.