Study On Electromechanical Double Acting Pneumatic Brake Vavle And Its Compound Braking Strategy

With excessive consumption of oil resources and environmental issues becoming increasingly serious, therefore new energy vehicles have been greatly promoted. For urban electric bus, due to its operating conditions and relatively large vehicle weight, a lot of energy is lost during braking, so it is very important to develop advanced braking energy recovery system. At present, most of the braking energy recovery system of new energy vehicles is parallel, and domestic research of pneumatic brake system based air brake-by-wire is still in the initial stage. Therefore, this paper studied pneumatic composite brake system based BBW, which will be applied to city buses, to make brake force distribution more flexible and to recover more braking energy.In this paper, an electromechanical double-acting pneumatic brake was designed by adding the electromagnet structure based on a parallel dual-chamber pneumatic brake, and then made the designed valve as the actuator of pneumatic brake system, and the scheme of pneumatic composite braking system based BBW was designed. The parameters of each component of the pneumatic braking system were matched to meet the requirements of the braking system, and the complete model of air brake systems was established. The built braking system could allow the control of the front and rear brake chamber pressure more flexible, and bye PID controller, the braking force was well controlled, which proved that the designed scheme of BBW was feasible.To maximize energy recovery, the composite brake control strategy based on maximizing energy recovery was established, making full use of the regenerative braking force provided by the motor. By analyzing the force of the vehicle and the wheels of the front axle and the rear axle, the three degrees of freedom model of the bus was established, and the model of motor, battery and tire of the bus was created simultaneously. Driving parameters were estimated based on recursive least squares, which made the regenerative braking force control algorithm proposed in various braking conditions. In ADVISOR software, the designed regenerative braking model in this paper was loaded into the default EV module, the energy recovery of electric buses was analyzed in different cyclic conditions.In order to verify the correctness of the designed pneumatic composite brake system by wire, the program of in the loop simulation test was designed and the real-time control platform based the x PC was built. According to the testing principle and the function of the braking system, the braking controller was designed, and the construction of the information acquisition system and the acquisition of the required parameters for test were completed. Finally, in the custom condition, the performance of composite pneumatic braking system by wire control was verified in the established test stand by using the three degrees of freedom model of vehicle braking, the results shown the effect of the designed energy recovery system was good.