Abstract:

Based on the PWM(pulse-width modulation) wave and VISA(virtual instrument software architecture) interface, a battery experimental system which is used to study the thermal characteristics of batteries is designed. The system can be used to carry out various discharging experimental in which batteries discharge by different drive cycles, such as NEDC(new european driving cycle), UDDS(urban dynamometer driving schedule), etc., and can collect the temperature information during the experiment, as well as its sampling frequency can be customized according to actual needs. The working principle of the PWM wave in the system is discussed. According to the NEDC, the PWM wave array with sampling accuracy of 0.1s is used to control the discharge of the battery, also verifies the reliability of the system when conduct experiment of thermal characteristics of the single-cell lithium battery with high-rate discharge. There is a new type of symmetrical DC/DC(direct current to direct current converter) which can achieve two-way step-up and down to facilitate the simulation of drive cycles; and a PWM wave generator to produce NEDC condition control signal to control the implementation of the PWM actuator. The reliability and accuracy of critical components of the system is also verified. Finally, NEDC experiments are conducted for the domestic mainstream 18650 batteries and discharge temperature curves are obtained.

Key words: PWM, drive cycle, lithium battery, VISA object