Voltage-sourced Converter fed High-speed SRM Drive System with Energy Feedback and Near-Unity Power Factor
Abstract : The diode bridge rectifier fed asymmetric halfbridge converter (AHBC) is conventionally employed to drive switched reluctance motors (SRMs), which leads to poor grid-side power quality. In the proposed system, a topology made up of a voltage-sourced converter (VSC) and an AHBC is employed to drive the high-speed SRM. Stable SRM operation can be obtained by manipulating the active power flowing to motor side, and on the basis of that, the grid-side power quality is enhanced by directly manipulating input reactive power. Predictive deadbeat control (P-DBC) with disturbance observer is employed to follow the power references, thereby achieving controllable speed, energy feedback, near-unity grid-side power factor (PF), and low grid-side current distortion simultaneously. Additionally, an improved asymmetric modulation method is developed for switching frequency reduction. Experiments are carried out to test the proposed drive system in steady and dynamic conditions. Performance comparisons validate the improvement of the proposed high-speed SRM drive system.
? In Comparison with the existing ac machines, Switched Reluctance Motor is in advancement as a lot of importance is given to this machine.
? The benefits comprise low cost, higher performance, higher strength and high fault tolerance.
? Various forms of converters area unit used for dominant the SRM drive. The major downside of SRM drive is massive torque ripples. However, this could be restricted to an outsized extent by part current overlapping.
? Therefore separate management is employed for the converters used in SRM drive. The torsion ripples area unit reduced by part current overlapping.
? In, based on the electromagnetic finite elemental analysis, the multiphysics acoustic modeling of ultrahigh-speed SRM is built to analyze the acoustic response to estimate the sound pressure level.
? One of the reasons that restricts the maximum speed of SRMs is the speed limit of commercial rotary encoders due to mechanical considerations.
? To address this problem, develops a direct position control based on the nonintrusive reflective optical sensor, and eliminates the conventional encoders by adopting the sensorless control scheme.
• The proposed converter working in discontinuous inductor current mode is used to regulate the DC output voltage and improves the power quality at the AC mains.
• The SC (Switched Capacitor) converter has been proposed recently. These SC based converter structure is a combination of switches, diodes and capacitors and such multilayer combination results in required DC voltage at the output side.
• The SRM drive proposed with SC (Switched Capacitor) converter as a front end PFC converter. It comprises of a SC circuit with a buck-boost combination of switch and inductor. The SC circuit consists of two diode (D1 and D2) and two capacitors (C1 and C2).
• The phase-locked loop and rotatory transformation are requisite in the system, both of which complicates the system control.
• Moreover, the dc bus voltage utilization ratio is just 50% due to the characteristics of that topology, and to ensure high performance, the balancing control for the dc bus capacitors should always be considered by an additional control loop which inevitably increases the system control complexity.
• The grid-side power quality enhancement as well as SRM regulation is the control orientation of the proposed system to improve the entire system performance.
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