Study And Design Of Control System For Inverter Air-Conditioner Of Truck

It is required that the truck air-conditioner be capable of running continually when parking or rest at night. Electric powered air-conditioner fits the trends of truck demands due to its advantages in efficiency and independence of running comparing with the traditional mechanical drive air-conditioner. Currently, the Electric powered air-conditioner is primarily designed for all-electric or hybrid vehicles which based on high voltage power supply,while there is a limit to the air-conditioner of low voltage drive for its high cost and hard to design for integration of the inverter, motor and compressor.Aiming at the problem of low operation efficiency and power restriction caused by large load current in the application of the electric powered air-conditioner system for truck, in this project,A drive scheme of electric powered air-conditioner is studied based on 24 V power supply and a 1k W motor control system of the air-conditioner compressor is designed. In this paper, the DC-DC converter is adopted to lift the voltage level and subsequently reduce the loss of the inverter and motor; a vector control scheme of Permanent Magnet Synchronous Motor based on changing DC bus voltage is adopted to improve operating efficiency. The study includes the following three aspects:(1) Design of two stage step-up DC-DC converterA two stage step-up DC-DC converter is adopted to the application with the 24 V power supply, the first stage for Boost converter to keep a constant 48 V output, the second stage for full-bridge isolated converter by the purpose of further boost of voltage and isolation of high and low side of voltage.(2) Design of Permanent Magnet Synchronous Motor driver based on changing DC bus voltageSince the compressor mainly worked in low speed condition, a vector control scheme based on changing DC bus voltage is adopted to reduce the loss in DC-DC converter and,in the meanwhile, improve quality of output voltage in inverter.(3) The establishment of semi-physical simulation system for the truck air-conditionerThe simulation model of the truck air-conditioner was established by Matlab; the semi-physical simulation platform based on Matlab GUI is built after the realization of the real-time control of the motor speed by using real time data exchange(RTDX) of Matlab and DSP.Based on the scheme design, a DC-DC converter and motor driver is manufactured and preceded by experimental verification. The result show that the test efficiency of the DC-DC converter is about 79% at the rated load of 20% and the voltage utilization ratio is improved through the realization of the control of bus voltage. At last, a simulation of temperature control effect under varied work status of heavy vehicles is conducted. The results show that the electric powered air-conditioner system has a higher independence of running and efficiency compared to the traditional air-conditioner.