Applied Mechanics and Materials Vol. 573

Abstract: The wide spread use of power electronics equipments in modern electrical systems, has became a major concern due to the adverse effects of harmonics on all the sensitive equipments. This paper presents the implementation of shunt active power filter (SAPF) using source voltage and source current detection. The control and implementation of SAPF is being done by instantaneous active and reactive power, PQ theory for the extraction of harmonics from the fundamental and for the generation of Pulses for the voltage source inverter (VSI), space vector pulse width modulation (SVPWM) is used. The harmonics present in the system are computed and the controller generates PWM signals to inject the compensating harmonic current back into the line to cancel the harmonic components in the distorted line. The performance of proposed topology is first examined by MATLAB-SIMLINK-based simulation and the prototype hardware has been developed using DSP TMS320F28027 processor and the results were verified. The Total harmonic distortion (THD) is below the specified limits.

Abstract: — this paper presents a digital current controller for H-bridge pulse width modulation (PWM) converters, whose sampling frequency equals quadruple of the switching frequency,. This current regulator detects the ac current and manipulates the voltage reference not only at the upper and lower peaks of the PWM triangle carrier but also at its zero crossings. A modified deadbeat current regulator is proposed to suppress the current oscillation induced by the voltage error, based on the theoretical analysis. Experimental results are shown to verify the control performance of the proposed current regulator. Moreover, a proposed current regulator is applied to a single-phase active power filter to demonstrate the effectiveness in harmonic compensation. Index Terms—Current regulators, digital control, DSPs, pulsewidth modulation (PWM), shunt active filters.

Abstract: This paper presents a discrete PWM controller for SEPIC (Single ended Primary Inductor Converter) converter. SEPIC is chosen since it has positive voltage gain and higher characteristics than any other converter. To improve the transient response and dynamic stability of the proposed converter, Discrete PID controller is the most preferable one. The proposed controller improves the dynamic performance of the SEPIC converter by achieving a robust output voltage against load disturbances, input voltage variations and changes in circuit components. The converter is designed through simulation using MATLAB / Simulink and performance parameters are also measured. The discrete controller is implemented, design goal is achieved and the same is verified against theoretical calculation using LabVIEW. Keywords: SEPIC converter, Discrete PID Controller, Analog to Digital Converter (ADC), Digital Pulse Width Modulator (DPWM).

Abstract: This article presents a comprehensive study on implementing four switch brushless DC (BLDC) motor drive for variable speed applications with PI controller. In this system, four switches are used in the commutation circuit to lower cost and improve performance. The reduction in the number of power semiconductor switches leads to reduction of losses and the control circuit. The principle of operation, switching sequence formulation for the four switch BLDC motor drive is presented. A PI controller is designed for speed control and evaluated by simulation for performance under various speed and load conditions. The designed closed loop controlled BLDC motor drive shows satisfying performance despite the reduction of switch count. The steady state error of the system is limited within 1% while improving the transient performance.

Abstract: —This The Pulse Width Modulation (PWM) DC-to-AC inverter has been widely used in many applications due to its circuit simplicity and rugged control scheme. It is however driven by a hard-switching pulse width modulation (PWM) inverter, which has low switching frequency, high switching loss, high electro-magnetic interference (EMI), high acoustic noise and low efficiency, etc. To solve these problems of the hard-switching inverter, many soft-switching inverters have been designed in the past. Unfortunately, high device voltage stress, large dc link voltage ripples, complex control scheme and so on are noticed in the existing soft-switching inverters. This proposed work overcomes the above problems with simple circuit topology and all switches work in zero-voltage switching condition. Comparative analysis between conventional open loop, PI and fuzzy logic based soft switching inverter is also presented and discussed. Keywords— Zero voltage switching, Inverter, Dc link, PI controller, Fuzzy logic system control ,Modulation strategy, Soft switching

Abstract: This paper proposes the natural extension of classic switching table based direct torque control of induction motor modified for 3-level diode clamped inverter. The proposed method has the advantages of fewer harmonic in the output and low torque ripples. The switching table direct torque control scheme is adopted due to the simplicity of its control algorithm. To demonstrate the performance of proposed multilevel inverter fed direct torque control, the simulations are carried out for constant speed under no load and step change in load. The comparison of the dynamic and steady state performance in terms of torque ripple of the 2-level inverter and 3-level inverters are presented.

Abstract: This paper presents improved Fuzzy Logic Controller (FLC) of the Direct Torque Control (DTC) of Three-Phase Induction Motor (IM) for high performance and torque control industrial drive applications. The performance of the IM using PI Controllers and general fuzzy controllers are meager level under load disturbances and transient conditions. The FLC is extended to have a less computational burden which makes it suitable for real time implementation particularly at constant speed and torque disturbance operating conditions. Hybrid control has advantage of integrating a superiority of two or more control techniques for better control performances. A fuzzy controller offers better speed responses for startup and large speed errors. If the nature of the load torque is varied, the steady state speed error of DTC based IM drive with fuzzy logic controller becomes significant. To improve the performance of the system, a new control method, Hybrid fuzzy PI control is proposed. The effectiveness of proposed method is verified by simulation based on MATLAB. The proposed Hybrid fuzzy controller has adaptive control over load toque variation and can maintain constant speed.

Abstract: This paper proposes the modeling of Single Ended Primary Inductor Converter (SEPIC) for Power Factor Correction (PFC) and PID control for the converter using various tuning methods. The SEPIC is capable of operating from an input voltage that is greater or less than the regulated output voltage. A small signal dynamic model for SEPIC PFC converter is obtained using state space averaging technique which provides a fifth order transfer function. The complete model of the converter is simulated using MATLAB (SIMULINK). Then the PID controller is designed for the SEPIC PFC converter and various tuning methods were adopted using SISO tool in MATLAB.

Abstract: In this work low leakage and high noise immunity domino circuit with negligible speed degradation is proposed. Wide Fan-In Gates are widely used as address decoders in memories. Wide Fan-In Gates increase the capacitance of the dynamic node which reduces the speed in domino circuits. Current contention exists between keeper transistor and evaluation network adding to speed reduction. To overcome this problem logic implementation network in the proposed Leakage Compensating Keeper (LCK) is separated from the dynamic node by current comparison stage in which the current of the pull up network is used to charge the capacitor at the dynamic node. Since capacitance is reduced the loss in speed due to additional transistors is compensated. Because of reduced parasitic capacitance Current Mirror based LCK is enough to design faster circuits. LCK improves the noise immunity by grounding the pull up networks leakage current. Simulation results shows that the proposed circuit has 22% power reduction compared to Standard Footless Domino for a 64bit input OR gate.

Abstract: In this paper, an area-efficient low power fast fourier transform (FFT) processor is proposed for multi input multi output-orthogonal frequency division multiplexing (MIMO-OFDM) in wireless communication system. It consists of a modified architecture of radix-2 algorithm which is described as modified radix-2 multipath delay commutation (MOD-R2MDC). The OFDM receiver with modified R2MDC (MOD-R2MDC) FFT was designed by Hardware Description Language (HDL) coding The Xilinx ISE Design Suite 10.1 is used as a synthesis tool for getting the power and area. The Model-Sim 6.3c is used for simulation. Also the existing OFDM system has been tested with these FFT algorithms and their performances were analyzed with respect to occupancy area in FPGA and power consumption. A low-power and area efficient architecture enables the real-time operations of MIMO OFDM system.