Position Sensorless Control Of Electric Vehicle Air Conditioning Compressor Based On Single Current Sensor

With the global energy crisis and the continuous destruction of the earth’s environment,the goal of sustainable development of human society is seriously constrained.And with automobiles as one of the major sources of oil consumption and CO2 emissions,the cries for change are overwhelming.In the last decade,vehicle electrification has been intensified to meet the requirements of reducing fuel consumption and greenhouse gas emissions,and air conditioning is an almost essential part of the vehicle,as it ensures both thermal comfort in the passenger compartment and is an indirect safety element,as it allows the driver to drive in optimal comfort conditions(defogging function).This function is operated by an air conditioning system with a compressor at its core.Usually,the compressor in conventional vehicles is driven by an internal combustion engine through an accessory belt,which limits its speed [1],especially in low-speed driving phases.In electric vehicles there is no internal combustion engine and therefore no belts but the need for an electric compressor.In recent years,companies in the automotive industry have realized the importance of this technological development.There is now a global consensus to use new energy as a source of power for automobiles,and in the long run,hybrid,pure electric and fuel cell vehicles are the main directions for the development of new energy vehicles.With the rapid development of electric vehicles in recent years,the OEMs and passengers have also put forward more stringent requirements on the comfort,energy efficiency and reliability of new energy vehicles.The air conditioning system of the vehicle will directly affect the energy efficiency of the vehicle and the comfort of passengers.The electric compressor is the core of the air conditioning system,and has become a hot research topic today.For the consideration of cost,quantity and system reliability,the work of this thesis is to propose innovative solutions concerning electric compressor control electronics,motors and related mechanical devices.In this paper,the system cost,load characteristics and energy efficiency of electric compressors are studied and explored in terms of system design,control strategy and simulation experiments.Thus,the ultimate goal is to have an electric compressor that is reliable,compact,efficient and optimized in terms of quality,size,efficiency and cost.First,the mathematical model of the relevant physical quantities in the electric compressor system is studied and modeled and simulated using the space vector pulse width modulation method.And the basic principle of phase current reconstruction technique is introduced and the blind area of phase current reconstruction is analyzed.Secondly,in order to achieve accurate phase current reconstruction in the whole voltage vector region,the conventional phase current reconstruction technique is improved to ensure that the dead zone problem is overcome and the phase current can be correctly reconstructed within the shortest duration of the effective voltage vector.Finally,in order to further reduce the system cost,the permanent magnet synchronous motor without position sensor technique is investigated and MATLAB/Simulink modeling simulations are performed in combination with the single current sensor control technique.The various techniques proposed above were also experimented on an electric compressor to verify the feasibility and effectiveness of the control strategy.