A SINUSOIDAL PULSE WIDTH MODULATION-BASED CONTROL SCHEME FOR IMPROVED EFFICIENCY AND TORQUE PRODUCTION IN SINGLE-PHASE INDUCTION MACHINES DEVELOPMENT AND SIMULATION
Capacitor-run single phase induction motors (CRSPIMs) are designed to run at a constant speed and drive rated loads in a wide range of applications such as heating, ventilating, and air conditioning systems (HVACs), pumps, compressors, fans, washing machines, hand driers, machine tools, grinding machines, vacuum cleaners, elevators, and so on. At rated loads and speeds, the currents in the main and auxiliary windings of the motors are approximately balanced (Pei et al,2016).
Balanced currents are those with a phase angle difference of 900 and a magnitude ratio equal to the effective winding turns ratio. At any other load and speed, the winding voltages and currents are unbalanced (Muljadi et al., 1993; Krause et al., 2002; Chomat and Lipo, 2003; Krischan et al., 2008), resulting in low efficiency and high noise levels (Blaabjerg et al., 2004; Mademlis et al. 2005; Asghari and Fallah, 2012; Hosseini, 2016).
In reality, some SPIM-driven industrial, commercial, and residential loads decrease over time, and this decrease is accompanied by an increase in speed (Spirov, 2016). As a result, motor efficiency decreases and torque pulsation levels in the machine rise, resulting in undesirable noise and vibrations (Park, 2001; Zahedi and Vaez-Zadeh, 2009). Furthermore, a significant amount of energy is wasted during light load operations because conventional SPIMs typically use between 60% and 80% of rated input power even when operating at less than half load (Saidur et al., 2012).
Electrical losses in alternating current (ac) induction machines can be reduced by lowering the magnitude of currents in the machine windings and lowering the air-gap flux (Benbouzid et al., 1996; Dong, 2005). According to research, there is an air-gap flux density in 2 an ac induction motor that produces the least amount of losses for any given load applied to the machine (Naxin et al., 2004; Dong, 2005).
Significant improvements in motor efficiency can be obtained by adjusting motor flux to meet load requirements. Furthermore, significant energy savings can be realized because power losses are reduced as flux levels in the machine are reduced.
The supply of balanced voltages and currents to the windings of the single phase induction machine has been investigated in this study, and a drive system that regulates the flux and output torque while maintaining a constant speed in a single phase induction machine has been developed to eliminate torque pulsations at steady state and to increase motor efficiency at light loads has been developed.
Several researchers have been looking into the problem of high torque pulsations and low efficiency in existing single phase induction machines for over fifteen years. The majority of this research has focused on improving motor efficiency and reducing torque pulsations at or near the rated load operating point.
Only a few publications deal with improving the performance of these machines at light load (or non-rated) operations, and even then, these publications (Mademlis et al., 2005; Zahedi and Vaez-Zadeh, 2009; Caruso et al., 2012; Jang, 2013) have focused on speed regulation rather than optimal flux regulation in single phase induction motors. The motivation for this research stems from a desire to fill a research gap in order to improve the performance of single phase induction machines.
1.3 THE IMPORTANCE OF RESEARCH
People in Nigeria are still suffering from a severe lack of electricity to meet domestic and industrial needs. To alleviate the shortage situation, new generating plants must be installed, as well as existing power resources must be used more effectively. Unfortunately, very little attention has been paid to improving efficiency and making better use of existing resources.
This study begins with an examination of the single phase induction machine, which is a significant consumer of domestic power supply, with the goal of improving its operation. Improvements in efficiency may allow this machine to consume less power and thus lower operating costs, allowing electric utilities' limited electric power resources to meet the needs of more customers.
The environment will be safer as a result of reduced heat loss and noise caused by the elimination of torque pulsations. This research finds significant national importance and relevance at this time in this context.
1.4 STATEMENT OF THE PROBLEM
When operating under non-rated conditions, the capacitor-run single phase induction motor has a low efficiency. This situation wastes a significant amount of electricity because the rated voltage is applied fully across its terminals and the flux in the machine operates at or near the rated value regardless of the applied load.
Furthermore, during startup and steady state, the motor exhibits significant torque pulsations, which causes noise and vibration in the machine. Low efficiency under light loads and vibrations cause electrical, thermal, and mechanical stresses on the machine, threatening its useful life.
Furthermore, the use of a centrifugal switch and capacitors makes this motor susceptible to failure if either or both of these devices fail.
1.5PURPOSE AND OBJECTIVES
The goal of this research is to create a control scheme that uses sinusoidal pulse width modulation (SPWM) to improve the efficiency and torque production of a single phase induction machine. The following are the research objectives:
a) To evaluate the existing CRSPIM's performance and to change the spatial angular displacement of stator windings in the existing CRSPIM in order to investigate any gains in torque production and efficiency.
b) Develop a method for providing balanced currents to existing CRSPIMs in order to eliminate torque pulsations during steady-state operation.
c) Develop a method for increasing efficiency and lowering power consumption in the existing SPIM significantly at light loads.
d) Simulate and compare the SPIM's performance under the proposed drive scheme to the performance of the line-operated CRSPIM.
e) Create a better stator winding layout for increased torque and efficiency in existing single phase induction machines.
The following is a brief summary of the methodology used in this research project:
a) Using reference frame transformation and harmonic balance techniques, a generalized model for simulating the dynamic and steady-state performances of the existing CRSPIM is developed.
b) Selection of a suitable inverter topology for the scheme. Identification and development of control strategies based on sinusoidal pulse width modulation that will allow torque pulsations to be eliminated at steady state.
c) Using an efficiency-optimizing formulation to investigate the performance of the inverter-drive scheme and evaluate its contribution to efficiency improvement.
5 d) Use of MATLAB/Simulink software to simulate and compare the proposed motor drive scheme's performance to that of an existing line-operated capacitor-run single phase induction machine.
e) Using standard winding layout design techniques, create a better stator winding layout for the existing machine.
The first chapter of this thesis provides research background information. It also contains information about the research's purpose and objectives. The research motivation, problem, methodology, and significance are also discussed. The second chapter examines existing literature as well as fundamental concepts relevant to the research.
Chapter three describes the materials and methods used to address the research problem, while Chapter four discusses the findings. The research findings are summarized in Chapter 5. It describes the limitations of the work and makes suggestions for future work. It also summarizes the important contributions made to the body of knowledge before concluding the thesis.
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A SINUSOIDAL PULSE WIDTH MODULATION-BASED CONTROL SCHEME FOR IMPROVED EFFICIENCY AND TORQUE PRODUCTION IN SINGLE PHASE INDUCTION MACHINES DEVELOPMENT AND SIMULATION