Pulse Width Modulation AC Chopper Research Articles

Implementation of PWM AC chopper controller for capacitor run induction motor drive via bacterial foraging optimization algorithm

<p>This paper focuses on design of closed-loop control for pulse width modulated AC chopper controlled capacitor run induction motor drive engaging enriched optimization algorithm based on foraging of bacteria. Capacitor run induction motor is a non-linear device and its parameter varies under different functional point of the system. A linearized increment model for PWM AC chopper is illustrated for a particular functional point of the drive. The conventional method does not provide acceptable performance under different load conditions. Bacteria foraging optimization technique categorizes accurate control parameters for the superlative dynamic response under unit step load variations. Field Programmable Gate Array is implemented practically for a particular functional point of the drive to exhibit accurate performance. Experimental and simulated results are obtained to authenticate the effectiveness of the optimized controller.</p><p> </p>

Current limiting soft starter for three phase induction motor drive system using PWM AC chopper

This study presents a new current-limiting soft-starter for a three-phase induction motor drive system using pulse width modulation (PWM) AC chopper. A novel configuration of three-phase PWM AC chopper using only four insulated gate bipolar transistors (IGBTs) is also proposed. The proposed control strategy does not require zero crossing detection circuits, which employed in thyristorised soft starters. It requires only one current sensor. The duty ratio of the chopper IGBTs is obtained from the closed-loop current control in order to limit the motor starting current at a preset value. Only two complementary gate pulses are obtained from the control circuit to control the four IGBT switches. The proposed control strategy is characterised by a simple control loop; thus, a low-cost processor can be used due to the low-computation burden. The superiority of the proposed strategy is proved theoretically and confirmed experimentally. The experimental work is developed using a laboratory prototype system composed of DSP-DS1104 digital control board and 1.5 HP induction motor. The proposed starter offers a smooth start-up for the motor speed, torque ripple minimisation, less number of semiconductor switches, less switching and conduction losses, less harmonics and improved input power factor.

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This paper presents comparison of closed loop results of single, two and four switch AC Chopper fed single phase induction motor. The Dynamic response of open loop system is poor. Closed loop system is used to improve the dynamic response. This paper deals with modeling and simulation of one switch, two switch and four switch AC Chopper fed single phase induction motor drives. The pulse width modulated AC chopper fed single phase induction motor is implemented using an Atmel 89C51 microcontroller. The intention is to save energy in operations using induction motors. At no load, 70% of the energy can be saved that decreases with an increase in the load. From the simulation results, it is seen that the pulse width modulated (PWM) AC chopper system has lesser harmonics than the phase controlled AC chopper system, and hence it is used in the present work. Closed –loop control scheme to implement the energy–saving in the single phase induction motor drive system is designed and presented. The possibility of energy saving is explored in loads like cutting, punching and drilling operations, where most of the time induction motors runs at no load. . .

Short Through Avoidance in AC-AC Choppers

This article discusses a new approach to improve the switching characteristics of a buck-AC chopper. Conventionally, a line voltage detection based switching algorithm is utilized for this purpose. A new switching strategy for a pulse-width modulated AC chopper has distinct advantages over a voltage detecting method, such as higher reliability, lower harmonic contents, and high efficiency. In addition, it can avoid the short through problem, which is inherent in conventional methods in the case of false zero crossing detection. Both methods are analyzed through simulation in MATLAB (The MathWorks, Natick, Massachusetts, USA). The advantage of the proposed approach is verified by experimental results using a laboratory prototype.

Power Factor Improvement and Voltage Harmonics Reduction in Pulse Width Modulation AC Chopper Using Bee Colony Optimization

This paper presents a new pulse width modulation (PWM) switching technique for a single phase AC chopper. In the proposed technique, the switching frequency is fixed and the optimal PWM switching angles are obtained by using bee colony optimization. This process can improve the input power factor and reduce the total harmonic distortion of the output voltage. The performance of the proposed technique is compared with that of the conventional PWM through the simulation and experimental results.

Performance Evaluation of Energy Efficient Speed Control Techniques for Capacitor-run Single-phase Induction Motor Driving Domestic Fans

This article shows the systematic evaluation of the performance of capacitor-run induction motor driving domestic fans using different power conversion methods. The power converters employed are AC/AC converters with phase angle control and multiple pulse width modulation AC chopper and integral cycle control. It is shown through extensive simulation and experimentation that phase angle control in the main winding of the fan motor yields improved results.

Steady State Analysis and Simulation of AC chopper Fed Capacitor-Run Induction Motors

This paper presents steady state analysis and simulation of single pulse width modulated ac chopper fed capacitor run induction motor for variable speed operation. The d-q axis model of the cpacitor run motor is used for simulation study. Experimental results are provided to validate the simulation study.

AC chopper voltage controller-fed single-phase induction motor employing symmetrical PWM control technique

Due to the growing demand in improving the performance of motor drives, there is an increasing need to improve the quality and reliability of the drive circuit. AC-to-AC converter schemes using pulse width modulation (PWM) are proved to achieve substantial advantages over conventional line-commutated AC controllers. With the increasing availability and power capability of MOSFET's and IGBT's switches, PWM converters can efficiently and economically be used in low and medium power applications. However, such controllers have been applied only to control the voltage of passive R-L loads. In this paper, the performance characteristics of a symmetrical PWM AC chopper controller-fed single-phase induction motor drive are evaluated. The developed analysis is experimentally verified by an experimental verified mathematical model is used for this purpose.

Three-phase ideal phase shifter using AC choppers

A three-phase ideal phase shifter using pulse-width modulation (PWM) AC choppers is proposed. The ideal phase shifter is made up of three single-phase PWM AC choppers and transformers for series quadrature voltage injection. The proposed phase shifter uses PWM AC choppers to solve the commutation problem and produces phase shift without amplitude variation. In the PWM AC chopper, the required switching operation to solve the commutation problem is achieved using regenerative DC snubbers. Previous phase shifters have utilised the source voltage as the input to the tap changer, but the proposed phase shifter utilises, simultaneously, the output and source voltage as the input to the PWM AC chopper. The proposed phase shifter gives phase shift without amplitude variation, high efficiency, fast dynamics, high reliability, and significant reduction of the filter size. It is also shown via simulation and experimental results that the proposed ideal phase shifter gives good dynamic and steady state phase shift performances. Experimental results obtained on a 6 kVA AC chopper are discussed.

A new configuration of single-phase symmetrical PWM AC chopper voltage controller

With the increased availability of power MOSFETs and insulated gate bipolar transistors, a new generation of simple choppers for AC inductive loads is foreseen. These new power semiconductors ease the use of forced commutations of thyristor switches to improve the supply power factor, even with highly inductive loads. The AC controllers with thyristor technology can be replaced by pulsewidth modulation (PWM) AC chopper controllers which have important advantages. In this paper, a symmetrical PWM AC chopper designed to operate with single-phase inductive loads with a reduced number of controlled switches is described. The operation as a variable voltage source of this converter is evaluated. This includes the conversion characteristics, harmonic generation, harmonic distortion factor, and input power factor. By digital simulation, these characteristics are investigated theoretically, and to correlate the measurements with theory, an experimental setup is presented to confirm the analytical analysis.

Novel PWM line conditioner with fast output voltage control

A novel pulse-width modulated (PWM) line conditioner with fast output voltage control is proposed. The line conditioner is made up of a PWM AC chopper and a transformer for series voltage compensation. In the PWM AC chopper, a proper switching operation for solving the commutation problem is achieved. Power semiconductor modules which are commercially available can be used in this circuit and regenerative DC snubbers are attached directly to power semiconductor modules to absorb the energy stored in line stray inductance. These regenerative DC snubbers have a very simple structure consisting of a capacitor only with no discharging resistors or complicated regenerative circuit for snubber energy. Therefore the proposed AC chopper gives high efficiency and high reliability. The output voltage of the line conditioner is controlled using rapid sensing of the output voltage. The optimal gains of the controller giving an output with small overshoot and adequate damping are designed using the time-weighted quadratic performance index. It is also shown using simulation and experimental results that the proposed line conditioner gives good dynamic and steady state performances with high quality output voltage.

Novel topologies of AC choppers

Novel topologies of pulse-width modulated (PWM) AC choppers for single-phase and three-phase systems are proposed for buck, boost and buck-boost types. A PWM AC chopper has important advantages compared with the phase-controlled AC controller using thyristors. The AC chopper has sinusoidal current waveforms, better power factor, faster dynamics, and smaller input/output filter. In an improved topology for AC choppers, an RC bypass snubber is used for minimising high-voltage spikes during the dead time in the gating signals of complementary switches. In the proposed topologies the commutation problem causing high-voltage spikes is resolved by intelligent gate-switching patterns using information from the input/output voltage. These switching patterns provide a current path for all operation modes without any RC bypass snubbers. Since RC bypass snubbers causing power loss are eliminated, the efficiency of the chopper is increased. Thus, advantages of the proposed topologies include increased power factor, low harmonic input current, fast dynamics, high efficiency, high reliability, high power capacity, and small size of the passive filter. The paper describes the operational principle and analysis of the proposed topologies. Experimental results show that the proposed topologies give good performance for AC choppers.

Reduction of vibration and acoustic noise in induction motor driven by three phase PWM AC chopper using static induction transistors

A three-phase pulse-width-modulated (PWM) chopper that uses a static induction transistor (SIT) to chop the three-phase AC voltage with a 20 kHz carrier frequency and control an induction motor is proposed. Harmonic components in the voltage and current waveforms do not appear in the audio frequency band with this method. When each terminal of the motor is connected to a 4 mu F capacitor, the terminal voltage and line current waveforms are almost sinusoidal. The motor speed is controlled by changing the on-time width of the gate signal. The power spectrum of the chopper-driven motor is calculated using a fast Fourier transform and measured. The results are used to reduce vibration and acoustic noise in the motor, which is confirmed by measurement. >

Symmetrically Pulse Width Modulated AC Chopper

Output voltage, output current and line current waveforms in a symmetrically pulse width modulated (SPWM) ac chopper are analyzed for harmonic content, displacement factor, distortion factor, power factor and efficiency. The results are compared with those of phase controlled ac chopper circuit to assess the superiority of SPWM ac chopper. A novel SPWM ac chopper with minimum number of active components is presented. The circuit operation and the design considerations are discussed.