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A novel auxiliary switch dc-dc converter with coupled inductor is presented in this paper. The proposed circuit achieves loss-less switching for both the main and auxiliary switches without increasing the main device current/voltage rating. A tapping in the pole inductor is added for the purpose of commutation. The proposed circuit is capable of operation at elevated switching frequencies of several hundreds of kHz, in a range of line and load variations. The proposed circuit is applicable to all isolated and non-isolated dc-dc converters. The performance and the design equations of the ZVS are identical for all types of dc-dc converters when the throw voltage and the pole current are properly defined. In the sections that follow, operating principle and theoretical analysis of the proposed circuit is outlined through the example of buck converter. Simulation and experimental results of 33 W,400 kHz boost converter are presented. Index Terms--Auxiliary switch converters, coupled inductor, resonant converters, zero current switching (ZCS), zero voltage switching (ZVS).

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.

In this paper, we analyze mutual coupling of switched reluctance (SR) motors with even and odd numbers of phases. We illustrate that SR motors with an even number of phases produce asymmetric mutual flux in different phases. On the other hand, an SR motor with an odd number of phases produces symmetric mutual coupling in all the phases. Then, we explain a practical way of measuring the mutual flux in SR motors and present the test results for an 8/6 pole, four-phase 4 kW motor. We simulated the performance of the SR motor with and without mutual flux, thereby demonstrating the effect of mutual flux on phase current, flux, and average torque. We verified the effect of mutual flux on position estimation by simulation and experiment. We show that appropriate correction for mutual flux may improve the accuracy of estimated position by 3[degrees], which will give better performance of the drive while driven without any shaft sensors. We also show that an SR motor with an odd number of phases is a better choice than one with an even number of phases because of its symmetric mutual coupling, its ability to utilize short flux paths, and the fact that it does not require costly bipolar excitation. Index Terms--Mutual flux, mutual flux measurement, position estimation, SR motor, steady-state performance, symmetric and asymmetric mutual coupling.

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.

In this paper the implementation of a simple yet high performance digital current mode controller that achieves high power factor operation for three phase boost rectifier is described. The indicated objective is achieved without input voltage sensing and without transformation of the control variables into rotating reference frame. The controller uses the concept of resistance emulation for shaping of input current like input voltage in digital Implementation. Two decoupled fixed frequency current mode controllers calculate the switching instants for equivalent single phase boost rectifiers. A combined switching strategy is developed in the form of space vectors to simultaneously satisfy the timing requirements of both the current mode controllers in a switching period. Conventional phase locked loop (PLL) is not required as converter switching is self-synchronized with the input voltage. Analytical formula is derived to obtain the steady state stability condition of the converter. A linear, low frequency, small signal model of the three phase boost rectifier is developed and verified by measurement of the voltage control transfer function. In implementation Texas Instruments's DSP TMS320F240F is used as the digital controller. The algorithm is tested on a 10-kW, 700-V dc, three phase boost rectifier. Index Terms--Distal current mode controller, DSP(TMS320F240) based implementation, high power factor operation, input voltage sensorless control, three phase boost rectifier.

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.

In this paper, a new variation of current mode control for high power factor operation of boost rectifier is presented. The general features are no input voltage sensing, no use of multiplier, and no inner loop current regulator. It therefore follows the same control structure as that of the linear peak current mode control and the non linear carrier control. However, it implements a different switching law for the modulator that extends the range of continuous conduction mode of operation. The switching principle of the modulator is predictive, as the actual current equals the reference current at the end of each switching period. The no. of reset integrators required in this modulator for generation of the carrier waveform is two. The steady-state stability analysis of the boost rectifier with the proposed predictive switching modulator (PSM) is presented in this paper. A low-frequency small-signal model of the boost rectifier switched by the PSM is developed for evaluation of the control transfer function. Experimental results on a 400-W boost rectifier prototype are presented. Index Terms--Boost converter, boost rectifier, continuous conduction mode, diode bridge rectifier, NLC, PFC, PSM, steady-state stability analysis.

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.