To develop an efficient variable speed compressor motor system

This research presents a proposed new method of improving the energy efficiency of a Variable Speed Drive (VSD) for induction motors. The principles of VSD are reviewed with emphasis on the efficiency and power losses associated with the operation of the variable speed compressor motor drive, particularly at low speed operation.The efficiency of induction motor when operated at rated speed and load torque is high. However at low load operation, application of the induction motor at rated flux will cause the iron losses to increase excessively, hence its efficiency will reduce dramatically. To improve this efficiency, it is essential to obtain the flux level that minimizes the total motor losses. This technique is known as an efficiency or energy optimization control method. In practice, typical of the compressor load does not require high dynamic response, therefore improvement of the efficiency optimization control that is proposed in this research is based on scalar control model.In this research, development of a new neural network controller for efficiency optimization control is proposed. The controller is designed to generate both voltage and frequency reference signals imultaneously. To achieve a robust controller from variation of motor parameters, a real-time or on-line learning algorithm based on a second order optimization Levenberg-Marquardt is employed. The simulation of the proposed controller for variable speed compressor is presented. The results obtained clearly show that the efficiency at low speed is significant increased. Besides that the speed of the motor can be maintained. Furthermore, the controller is also robust to the motor parameters variation. The simulation results are also verified by experiment

A bridgeless Cuk PFC converter

A bridgeless Power Factor Correction (PFC) circuit based on Cuk converter is proposed in this paper. The operation during each sub-interval modes of the converter operated in Discontinuous Conduction Mode (DCM) is discussed. The smallsignal and large signal models are presented using Current Injected Equivalent Circuit Approach (CIECA). PLECS/Simulink is used to verify the capability of the proposed converter to regulate the output voltage while the input current regulation is inherent. This converter is capable to operate in universal input voltage condition

Dynamic Evolution Control for Fuel Cell DC-DC Converter

Fuel cells are new alternative energy resource that has a great promise for distributed generation and electric vehicle application. However, fuel cells have a slow response due to their slow internal electromechanical and thermodynamic response. To optimize the fuel cell system performance, a fuel cell DC-DC converter with an appropriate controller which can regulate the power flow and automatically adjust the converter output voltage is needed. This paper proposes a new control technique for fuel cell DC-DC power converter. Design of the proposed control method for fuel cell DC-DC power converter is provided. A new approach for converter controllers synthesis based on dynamic evolution control theory is presented. In this paper, synthesis example of boost DC-DC converter is discussed. Performance of the proposed dynamic evolution control under step load variation condition is simulated under Matlab-Simulink environment. Simulation results show that the proposed techniques are capable for controlling fuel cell DC-DC converter

Seven levels symmetric H-bridge multilevel inverter with less number of switching devices

This paper proposes a new topology of a cascaded multilevel inverter that utilises less number of switches than the conventional topology. The proposed topology maintains the performance of conventional 7-levels output multilevel inverter while reducing the loss of power, installation area, converter size as well as development cost. The circuit development consists of six switches and one diode. With less number of switching devices in the circuit, there will be a reduction in the gate driver circuits and also in effect fewer switches required for specific intervals of time. Simulation works have been conducted to validate the proposed MLI topology. It is envisaged that the proposed topology can be applied for the system that requires high efficiency and a low electromagnetic interference

Curve fitting technique for optimal pulsewidth modulation (PWM) online control of a voltage source inverter (VSI)

A curve fitting technique to allow online computation of switching angles based on the optimal PWM switching strategies is presented. Detailed description of the curve fitting technique as applied to the optimal PWM switching angles trajectories for a VSI particularly for AC power conditioner or UPS applications is provided in this paper. This includes some analysis on the accuracy of the calculations based on the curve fitting technique compared with the exact solutions. The approach taken to actually implement this technique on a practical system is also highlighte

Modeling and simulation of a new Bridgeless SEPIC power factor correction circuit

AnewBridgeless PFC circuit based on Single-Ended Primary Inductance Converter (SEPIC) is proposed in this paper. The new topology has less component count and less conducted component during each mode of operation within one switching period. The small-signal and steady-state model of the circuit operated in Discontinuous Conduction Mode (DCM) is derived using the Current Injected Equivalent Circuit Approach (CIECA). The large-signal model based on state-space and switch model are also developed to verify the large-signal behavior. The simulation results of the proposed converter show that the output voltage of the proposed converter is successfully regulated to its desired value while the input current regulation is inherent