DC Energy Measuring equipment for Electric Vehicle Charger

DC chargers have the advantages of faster charging and higher efficiency compared with AC chargers, so that electric vehicles (EVs) can replenish fuel in a shorter time like traditional vehicles. It is of great engineering significance to realize the DC energy measurement of EV chargers for the safety and reliability of charging. In this paper, a high-precision, high-term stability Measuring equipment for DC energy is designed. The accuracy and long-term performance of the Measuring equipment is experimentally tested, and the effect of ripple on the accuracy of the Measuring equipment under high-power working conditions is further studied. The results show that the energy error of the measuring equipment is within 0.1%, meaning the accuracy level reaches 0.1 S The equipment can effectively verify and calibrate the 1.0 S level DC energy devices and comprehensively evaluate the measurement performance of the DC energy device. As for long-term performance, the energy measurement error of the equipment is within the allowable range during the test time of 1200 s. There is no over-tolerance of the energy measurement caused by component heating, which can meet the long-term energy measurement on the electric vehicle charger. Moreover, when the ripple content in DC charging is less than 5%, it has little effect on the energy measurement and can be ignored. But when the ripple content exceeds 5%, the measurement error increases significantly. In that case, the influence of ripple cannot be ignored, and effective ripple suppression technology needs to be adopted to improve the measurement accuracy.