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In this paper, a control strategy for reduced acoustic noise and sensorless operation of a switched reluctance (SR) motor is proposed for heating, ventilation, and air conditioning (HVAC) application, where the magnitude of the dc-bus voltage is controlled as a function of speed and the motor is operated in a single-pulse mode for all speed range. The dc-bus voltage is controlled by incorporating a dc chopper between the three-phase line rectifier and a split dc-link capacitor-type four-switch power converter. Such controller reduces the acoustic noise, provides more accurate position estimation for sensorless operation, and improves the life expectancy of the motor. The algorithm is first simulated through MATLAB/SIMULINK and then tested on a four-phase 8/6-pole 4-kW SR motor. The test results of achieved acoustic noise and improved sensorless operation are presented. Through the proposed method, the acoustic noise is reduced by almost 15 dB compared to the conventional scheme at low-speed regime. The proposed method is intended to drive a fan type of load in HVAC applications, where the dynamic performance requirement is not a stringent criterion. Index Terms--Heating, ventilation, and air conditioning (HVAC) application, low acoustic noise switched reluctance (SR) motor, radial force and vibration, sensorless operation, single-pulse operation.

This paper proposes a control method that can balance the input currents of the three-phase three-wire boost rectifier under unbalanced input voltage condition. The control objective is to operate the rectifier in the high-power-factor mode under balanced input voltage condition but to give overriding priority to the current balance function in case of unbalance in the input voltage. The control structure has been divided into two major functional blocks. The inner loop current-mode controller implements resistor emulation to achieve high-power-factor operation on each of the two orthogonal axes of the stationary reference frame. The outer control loop performs magnitude scaling and phase-shifting operations on current of one of the axes to make it balanced with the current on the other axis. The coefficients of scaling and shifting functions are determined by two closed-loop proportional-integral (PI) controllers that impose the conditions of input current balance as PI references. The control algorithm is simple and high performing. It does not require input voltage sensing and transformation of the control variables into a rotating reference frame. The simulation results on a MATLAB-SIMULINK platform validate the proposed control strategy. In implementation Texas Instrument's digital signal processor TMS320F240F is used as the digital controller. The control algorithm for high-power-factor operation is tested on a prototype boost rectifier under nominal and unbalanced input voltage conditions. Index Terms--Boost rectifier, current-mode control, high-power-factor rectifiers, input current unbalance, input voltage unbalance, power-factor correction.

This paper proposes a new strategy for harmonic filtering of a three-phase shunt active filter system. The shunt harmonic filter's control objective is defined as: balance the phase angle of the input current with the phase angle of the line frequency component of the load current. This objective is achieved in digital implementation without sensing the input voltages. The controller uses a phase-shifting method on the sensed input current and then applies the resistor-emulator-type input-current-shaping strategy on the phase-shifted current. In implementation, Texas Instrument's digital-signal-processor-based unit TMS320F240 EVM is used as the digital hardware platform. The control algorithm is computationally simple yet the harmonic filtering performance is high. The analysis, simulation, and experimental results of a three-phase shunt active filter prototype on a 25-A nonlinear load are presented. Index Terms--Digital-signal-processor (DSP) TMS320F240-based implementation, harmonic filter, phase-angle balance (PAB) control, shunt active filter (SAF), voltage-sensorless operation.

The objective of this paper is to present a simple yet accurate implementation of a resistor-emulator-type line-current-shaping controller for high-power-factor operation of a flyback rectifier. The important feature is that input voltage sensing is not required. In the circuit realization of the controller, no multiplier is used. Current shaping is performed directly on the input filter inductor current. The modulator uses only one reset integrator for the generation of duty ratio. The analysis presented in this paper shows the effect of input filter capacitance on discontinuous conduction mode of operation of the flyback inductor. Design equations for selection of the input filter components are derived. A low-frequency small-signal model of the rectifier is developed and verified by measurement up to 1 kHz. The performance of the controller is first tested by the SABER circuit simulator package. Then, a 100-W 110-V ac input 50-V dc output single-phase flyback rectifier prototype is built for experimental verification. Index Terms--Current-mode control, discontinuous-conduction-mode operation, flyback rectifier, high-power-factor rectifiers, power-factor correction.