Harmonic Analysis of Separately Excited DC Motor Drives

This Harmonic Analysis of Separately Excited DC Motor Drives describes about the design and harmonic analysis of Single Phase PWM rectifier with DC motor drives to reduce the current harmonics of the PWM rectifier. A PWM switching technique reduces the harmonics. Comparison of single phase PWM rectifier and single phase controlled rectifier is presented with the use of MATLAB simulation and the programming is accomplished in FPGA to generate gating signals. 

PWM rectifier is power converter to convert an ac to dc that is implemented with power electronic semiconductor switches like MOSFET and IGBT. PWM rectifiers have bidirectional power flows used in battery charger, UPS system, regulated dc voltage source. 

SCR converters have low power factor that result in higher order harmonics. Because of the advent of fast semiconductor devices like MOSFET, IGBT, and pulse width modulation techniques, passive filters are replaced with PWM rectifiers.

The conversion of electric energy is done by semiconducting converters that led to the growth of negative phenomenon to be negligible. Therefore the development of semiconductor structures enabled transmission of higher power to have wide spread of converters.

The block diagram of consists of Power circuit, Load, FPGA controller, Optocoupler, and Driver circuit. A single phase AC supply is fed to the power circuit; the power circuit converts AC/DC where AC supply is converted to DC. Power semiconductor is triggered by the gating signals in the power circuit.

There are two kinds of MOSFETs.  They are Depletion type MOSFET and Enhancement type MOSFET. The converter switches are turned ON and OFF during a half cycle in a PWM control.


The PWM is used to control rectifiers to eliminate the problems occurred by using phase controlled rectifiers. Hence the PWM rectifiers performs well in many applications like battery charger, UPS system, regulated DC voltage source. The PWM rectifier asserts with its good behavior in many applications and thyristor rectifiers controls load supply grid with consume reactive power and higher harmonics.

Download Harmonic Analysis of Separately Excited DC Motor Drives Electrical and Electronics Engineering EEE Final Year Project Report.

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