Research on the influence of the proportional relay valve on the economy and safety of the electric bus through the braking energy recovery system

To research the influence of the proportional relay valve on the economy and safety of the electric bus through the braking recovery system, a proportional relay valve model was proposed. Based on the analysis of the structure and working principle of the solenoid on/off valve, a dynamic model of “electro-magnetic-machine-air” coupling was simulated and analyzed. Then, based on the solenoid on/off valve and proportional relay valve, two pressure regulator modules were designed, the braking energy recovery system schemes were designed, respectively. Fuel economy tests were carried out under China city bus typical driving cycle based on two kinds of air pressure regulating module to research the influence of the proportional relay valve on the economy of the electric bus. An integrated control system of braking energy recovery and anti-lock braking system based on the proportional relay valve was proposed, hardware-in-the-loop braking energy recovery system contrast tests of the anti-lock braking system were also carried out based on two kinds of air pressure regulating module. The test results indicated that the proposed braking energy recovery system schemes were effective. The test results also demonstrated the economic contribution rate of the braking energy recovery of the proportional relay valve pneumatic control module was slightly higher than that of the proportional relay valve. Meanwhile, the proportion relay valve pressure regulating module achieved a good target speed follow and the accurate adjustment of air pressure in anti-lock braking system control.