PULSE WIDTH MODULATION CONTROL OF D.C. MOTOR

Abstract

In industrial applicat-ions I

the motor speed control is

required over a wide range with a good accuracy and time response from no-load to full load. Thyristors have been applied in the field of chopper control for many years ago , but the power MOSFETs have advantages over thyristors .The MOSFETs are lower in voltage drop, faster in switching and need no commutation devices.

In this thesis, a complete modeling and numerical simulation are proposed for a system consists ,'of a separately excited DC. motor either fed from a sinusoidally or uniform pulse width modulated converter through a power MOSFET taking the

impedance

of input transformer

into consideration.The

differential equation describing th behavior of the

proposed system in different modes ( _given.Solving these equations enable to

of operation are

predict the motor

performance/in both transient and steady-state conditions .

Using Fourier series,the steady-state waveforms are analyzed into their harmonic contents . The effect of duty ratio is

I