Design of Closed Loop Boost Converter fed Separately Excited DC Motor and its Wavelet based Denoising

Generally, a DC motor is utilitarian for precise, variable speed applications by varying its armature voltage. Therefore, to control the speed of a separately excited DC (SEDC) motor, the Dc-Dc step up converter is designed in this paper with its feedback structure. In open loop mode, this converter can boost the voltage from 40 Volt to 160 Volt to obtain a speed that is lower than the motor's rated speed. To track the reference speed by keeping the armature voltage constant, a proportional integral (PI) controller is compared to the repetitive saw-tooth waveform to generate the switching pulse of the boost converter. This closed loop structure is then implemented in real time experimentation to operate the 12 Volt motor by stepping up to 3.67 Volt in the closed loop structure of this converter in Arduino Uno microcontroller platform. This hardware model is also tested for an IOT based home automation system for controlling the portable small fan. Due to the presence of current or voltage sensors as well as different semiconductor devices may contaminate noise to the motor output. Therefore, to overcome this real concern, a Gaussian white noise is added to the inductor current in simulation both in resistive as well as SEDC motor loads. To denoise the noisy inductor current for both cases, a discrete wavelet transform (DWT) based denoising technique is applied and here, a modified VISU shrinkage is used to discard the noise via the soft thresholding method. The denoising performances in terms of signal to noise ratio (SNR) and mean squared error (MSE) are calculated for three different wavelets such as Daubechies (Db), Symlet (Sym) and Discrete Meyer (Dmey) wavelet. Here, the performances of the DWT based filter are compared with the conventional filter and interval dependent denoising method. Similar denoising steps are followed to discard the noisy coefficients of the inductor current obtained from the real time converter and the noisy output speed response of SEDC motor.