No abstract

In recent times, the use of industrial Heating, Ventilation, and Air Conditioning (HVAC) systems has had a substantial increase due to various social-economic reasons. Various studies are conducted to address the concerns of noise generated by HVAC systems in particular from compressors; noise pollution affects the environment we live in and should therefore be mitigated as much as possible. For this purpose, an active noise reduction system is introduced to help alleviate noise levels at both low and high frequency ranges of the HVAC system. This paper demonstrates an implementation of Active Noise Reduction (ANR) system using Least Mean Square (LMS) and Filtered-x Least Mean Square (FxLMS) algorithms, which have been tested based on simulated noise scenarios. A comparison between both algorithms will be performed based on simulation of different frequency ranges which closely resembles the operating scenario of the industrial HVAC systems. Also, different values of step-size affecting the processing of the ANR system during the convergence rate and stability state will also be investigated and discussed.

A small-signal analysis of a single-stage bridgeless boost half-bridge alternating current/direct current (AC/DC) Converter with bidirectional switches is performed using circuit averaging method. The comprehensive approach to develop the small signal model from the steady state analysis is discussed. The small-signal model is then simulated with MATLAB Simulink. The small-signal model is verified through the comparison of the bode-plot obtained from MATLAB Simulink and the simulated large signal model in piecewise linear electrical circuit simulation (PLECS). The mathematical model obtain from the small-signal analysis is then used to determine the proportional gain K_p and integral gain K_i. In addition, the switch large-signal model is developed by considering the current and voltage waveforms during load transients and steady-state conditions.