A NEW APPROACH TO PERFORMANCE ANALYSIS OF CHOPPER CONTROLLED D.C. MOTOR DRIVE

ABSTRACT

An analytical method for performance analysis of a d.c. separately excited motor fed from a chopper is presented. The motor input voltage is represented as a series of step-voltages with a time phase difference. The system equations are solved to obtain closed-form solutions for motor current and speed, for transient as well as steady state conditions. The method presented is superior to existing methods in that the solution is in closed-form, and does not make recourse to recursive numerical techniques. The solutions for steady state condition corresponding to any set of operating conditions (voltage, chopper duty factor, load torque) can be directly obtained. The computational effort and time needed is therefore extremely small as compared to other methods.     

SIMULATION OF CHOPPER FED D. C. MOTOR DRIVE SYSTEM-PROBLEM ORIENTED APPROACH

ABSTRACT

The purpose of this article is to develop an efficient simulation program for the steady state performance of a chopper fed separately excited D.C. motor drive system. The effectiveness of this method lies in the evaluation of the initial state vector of a state equation representing chopper-electromechanical system without passing through the transient region. Effects of source impedance, chopper circuit configuration/parameters have been discussed in detail to prove the generality of this simulation approach.     

PERFORMANCE ANALYSIS OF A D.C. DRIVE ELECTROMECHANICAL SYSTEM WITH ELASTIC COUPLING AND PULSATING LOAD TORQUE

ABSTRACT

This paper presents the analysis of a d.c. motor drive with a pulsating load torque and elastic mechanical link between the motor and the load. A mathematical model of the system using State Space technique is given and the equations are solved to obtain closed-form solutions for motor speed and current under transient and steady state conditions. The analysis reveals that the system performance is significantly affected by elasticity of the shaft and the nature of pulsation of load torque     

GENERALIZED METHOD OF ANALYSIS OF CHOPPER-FED DC SEPARATELY EXCITED MOTOR UNDER REGENERATIVE BRAKING

ABSTRACT

A generalised method of analysis for predicting performance of d.c. separately excited motor under regenerative braking controlled by load current commutated chopper, has been presented. It has been shown that the source inductance, in the absence of filter capacitor at the source terminals, considerably influences the chopper commutation and machine performance. It has experimentally been shown that the use of a suitable filter capacitance at the source terminal neutralizes the effect of source inductance. Calculated characteristics agree well with the experimental results     

Development of a Power Management Algorithm for PV/Battery Powered Plug-In Dual Drive Hybrid Electric Vehicle (DDHEV)

Abstract

In this paper, a Three-Port Dual Boost (TPDB) DC-DC converter operated Hybrid Electric Vehicle (HEV) based on dual motor drive system is presented to minimize Carbon Dioxide (CO₂) emission and to increase the fuel efficiency. The Dual Drive Hybrid Electric Vehicle (DDHEV) system composed of Photovoltaic (PV) system/plug-in, dual drive system and power management algorithm improves the fuel efficiency of the DDHEV. The DDHEV system designed with the PV system needs efficient and simple DC-DC converter to export the power generated by the PV system to motor/battery. The simulation results of the HEV structured in the MATLAB/Simulink and the experimental prototype models are introduced to evaluate the proposed PV-DDHEV under various conditions. From the results, it is found that the dual motor drive system operated by the TPDB provides better stability and reduces the power consumption.     

INVESTIGATIONS ON DYNAMIC BEHAVIOR OF PERMANENT MAGNET BRUSHLESS DC MOTOR DRIVE

ABSTRACT

Permanent magnet brushless dc (PMBLDC) motors are increasingly being used in a wide range of applications such as machine tools, robotics and high precision servo applications. A comprehensive analysis which includes modeling and simulation of PMBLDC motor drive is presented in this paper. A mathematical model of the drive is developed with a view to studying the transient response of current controlled voltage source inverter (VSI) fed PMBLDC motor. The drive system consists of discrete PID(Proportional, integral plus derivative) speed controller, the reference current generator, the position sensor, an inverter and the motor. Each part of the drive system is modeled separately and then integrated to study the dynamic behavior of the drive system. The study also examines the effectiveness of the drive system during starting, load perturbation, speed reversal and dc link voltage fluctuation.     

PERFORMANCE STUDY OF A CHOPPER-CONTROLLED INDUCTION MOTOR

Abstract

In this paper, the speed of an induction motor is controlled using a chopper circuit on the rotor side. Analysis of transient, including switching power supply and changing in duty cycle of chopper, and steady-state performance of the chopper-controlled induction motor are predicted-Analysis and simulation consider the induction motor equations from the rotor side where a diode bridge is connected. Experimental results are obtained to verify predicted behaviour based on this digital simulation.     

PERFORMANCE AND ANALYSIS OF CHOPPER FED D.C. SEPARATELY EXCITED MOTOR UNDER REGENERATIVE BRAKING

Abstract

A method is presented here to analyse the performance of a separately excited d.c. motor under regenerative braking mode and provides a technique to select the necessary inductance to reduce the ripple in the armature current as well as to eliminate the discontinuous conduction of the armature current and to optimize the regenerative power. The effect of armature reaction and also that of chopper commutation interval have been taken into account. The calculated performance agrees very closely with the experimental results.     

ANALYSIS OF STATE FEEDBACK CONTROL OF CHOPPER DRIVEN SEPARATELY EXCITED D.C. MOTOR

ABSTRACT

Armature voltage control of d.c. motor speed to a set point in the face of large step torque changes can be treated as a regulation problem in linear system theory. By proper pole assignment, one can have complete control over the dynamics of the closed loop system. The control input comes out as a function of the states, motor speed and armature current respectively, and integral of the output (speed error). The paper deals with separately exicited d.c. motors fed from a thyrister chopper circuit controlled by the state feed back signal. Discontinuous mode of current conduction in the chopper gives rise to unwanted swings in the dynamic response of the system. The proposed approach models the system taking discontinuous mode of current conduction into account, obtains the feed-back constants and predicts the oscillations that may come into picture at low shaft torques. Also a time varying model in proposed and this gives the designer an insight into the working of the system and guides him in his choice of the feedback coefficients. The proposed regulation method has been tested on a laboratory model d.c. motor, and the experimental and the theoritically predicted response curves are found to be in agreement     

A CHOPPER FOR CONTROL OF DC TRACTION MOTOR

Abstract

The paper describes a new chopper circuit capable of wide range of output voltage control and high frequency operation. The chopper has been analysed taking line inductance into account and expressions have been presented for the calculation of commutation circuit component parameters. A method has been presented for the calculation of motor performance and ripple in armature current. It takes into account the non-linearity of motor magnetic circuit and the effect of commutation pulse on motor performance.     

TRANSIENT AND STEADY-STATE ANALYSIS OF A VOLTAGE CONTROLLED INDUCTION MOTOR DRIVE WITH DELTA CONNECTED WINDINGS

ABSTRACT

This paper deals with the transient and steady-state analysis of a voltage controlled induction motor (VCIM) drive with delta connected windings. Symmetrically triggered back-to-back connected thyristor pairs are used in each of the three lines to effect change in terminal voltage. Using a three-phase stator side equivalent circuit of the induction motor, the state equations for different modes of operation are formed and solved using a digital computer. The results of the transient and steady-state analysis for a specified triggering angle and load torque are presented and compared with those for a wye connected motor.     

PERFORMANCE AND ANALYSIS OF CHOPPER FED D.C. SERIES MOTOR UNDER REGENERATIVE BRAKING

ABSTRACT

The paper presents a method of analysis and performance of chopper fed dc series motor under regenerative braking. The method of analysis takes into account the nonlinearity of the magnetic circuit, armature reaction, effect of commutation pulse and source inductance. Equations have been derived for the calculation of (a) machine speed-torque characteristics (b) regenerative power and efficiency of regeneration, and (c) current ripple and filter inductance value. The method also shows the prediction of stability at low speeds and conditions for failure of regeneration. The effects of chopper operating frequency, source inductance, commutation capacitor and input-filter capacitor on regenerative power and efficiency of regeneration, and stability of braking have been described. Theoretical deductions have been verified experimentally     

A DC Motor Control System for Electric Vehicle Drive

A control system of a dc separately excited motor for electric vehicle drive is described. The armature of the motor is controlled by a thyristor chopper, whereas the field is regulated by a highfrequency transistor chopper. The control scheme combines the advantages of both series and shunt motors and permits maximum possible acceleration within the transient thermal ratings of the motor. In addition, motor torque becomes smoother under all operating conditions. A complete drive system has been formulated, designed, and analyzed, and performances have been evaluated on a hybrid computer. At present, the breadboard of the drive system is being tested in the laboratory.     

SIMULATION OF A 1-PHASE STATIC CONVERTER-D.C. MOTOR DRIVE SYSTEM

ABSTRACT

Simulation of a static converter feeding a separately excited d.c. motor to obtain the unique steady state performance without passing through the transient region is presented. Single phase fully controlled bridge la chosen with a view to distinguish the various modes of conduction. At first a conventional way of presenting the simulation results for a chosen delay angle and back e.m.f. is attempted with the assumption of a constant speed of operation for the d.c. motor. Later on an alternative approach nearer to a practical situation is proposed involving the simulation of the system given the delay angle and load torque. In all these cases the effect of source impedance is also studied     

Computer-Aided Analysis of a Converter-Fed Saturated Synchronous Motor Drive

ABSTRACT

A method of numerical simulation for evaluation of the performances of a variable speed synchronous motor drive is developed. The machine has rotor saliency with armature and damper windings. Magnetic saturation in both d and q axes are also taken into consideration. The model is focused specially for analysis of a self-controlled reluctance motor drive fed either by voltage source inverter or current commutated inverter. The computer solution permits accurate calculation of current, voltage, and torque waveforms. Sample calculations for highly saturated converter-fed reluctance motor drive are presented including comparison with practical tests.     

DYNAMIC MODEL OF CHOPPER FED DC SEPARATELY EXCITED MOTOR

ABSTRACT

This paper describes the transient response of a chopper fed dc separately excited motor using time ratio control. An approximate second order model for predicting the transient behaviour of the motor is developed using perturbation technique. The transient response for small and sudden variations of duty interval and load torque is deduced during discontinuous and continuous current mode operations. The effect of external inductance on the performance of motor in the armature circuit has also been investigated. The results are compared with those obtained from a digital computer by numerically solving the simultaneous differential equations valid for different intervals of chopper cycle and also with the first order model. It is shown that the second order model is more accurate than the first order model and much simpler and efficient than the numerical approach. The theoretical results obtained are also verified with an experimental set up. Experimental results closely agree with theoretical predictions.     

ANALYSIS OF CONVERTER CONTROLLED DC SERIES MOTOR. I. STEADY STATE ANALYSIS

ABSTRACT

The steady state and transient analysis methods of converter-fed dc series motor reported so far do not take into account the nonlinearity of the magnetic circuit. Furthermore, for transient analysis discontinuous conduction has been neglected and only first order model has been reported though series motor is essentially a second order system. In the present paper steady-state and transient analysis methods have been presented for fully-controlled and half-controlled converter-fed dc series motor taking the nonlinearity and discontinuous conduction into account.

The paper has been divided into two parts. Part I presents various approximations for the nonlinearity of the magnetic cir-circuit methods of calculating steady state performance and a method of calculating a suitable value of filter inductance. Theoretical deductions have been verified experimentally

Part II of the paper presents the methods of transient analysis     

EFFECTS OF LOAD INDUCTANCE ON THE RIPPLES OF MULTIPHASE CHOPPER CONTROLLED DC MOTOR DRIVE

ABSTRACT

This paper derives simple expressions to calculate the ripple currents and voltage of a multiphase chopper control DC motor drive. A typical example is considered and the results of the simple equations are compared with those obtained from the solutions of the differential equations without approximations. The effects of the load current ripple and the multiphase operation of choppers on the ripple voltage and current of the ‘LC’ input filter are also evaluated.     

A SOLID STATE RESISTANCE CONTROLLER FOR 3-PHASE SLIP-RING INDUCTION MOTOR

ABSTRACT

A solid state rotor resistance controller incorporating triacs for varying the speed of 3-phase slip-ring Induction motor delivering a constant load torque is presented. Using this controller, it is possible to vary the speed of the motor continuously from a definite minimum speed to a definite maximum speed. The controller is simpler and more reliable compared to phase controlled or chopper controlled resistance controllers.     

REDUCTION OF DC TRACTION MOTOR ARMATURE COPPER LOSSES THROUGH OPTIMAL CONTROL

ABSTRACT

An optimal control that minimizes energy dissipated as armature copper losses for a thyristor converter powered DC drive motor subjected to acceleration under conditions of constant field excitation is presented. Pontryagin's Maximum Principle is employed in the control derivation. A closed-form expression for the optimal control in terms of system parameters is found.

Effectiveness of the control to reduce losses is demonstrated through example. In addition, nature of armature current and motor speed resulting from application of the optimal control are examined. Design trade-offs and implementation techniques are explored.