Accurate Speed Control of the DC Motor for Anti-Lock Braking System 2015-01-0654

The permanent-magnet DC motor, which is directly connected to the hydraulic pump, is a significant component of hydraulic control unit (HCU) in an anti-lock braking system (ABS). It drives the pump to dump the brake fluid from the low-pressure accumulator back to master cylinder and makes sure the pressure decreases of wheel cylinder in ABS control. Obviously, the motor should run fast enough to provide sufficient power and prevent the low-pressure accumulator from fully charging. However, the pump don't need always run at full speed for the consideration of energy conservation and noise reduction. Therefore, it is necessary to accurately regulate the speed of the DC motor in order to improve quality of ABS control.

In this paper, an accurate speed control algorithm was developed for the permanent-magnet DC motor of the ABS to implement the performance of the system, reduce the noise and save the energy in the meanwhile. Firstly, the hydraulic brake system and the DC motor models of the ABS were established in the AMESim and Matlab/Simulink respectively, and the data exchange was realized through AMESim special interface module and MATLAB S function. Then, the co-simulation model was validated by the experiment data. Furthermore, an accurate speed control algorithm for DC motor was developed based on the charging state of the low-pressure accumulator, and a pulse width modulation (PWM) method was proposed to control the speed of DC motor. Finally, the proposed algorithm was simulated in the co-simulation platform to verify the decompression response speed of the wheel cylinder and the energy consumption of the DC motor. The results show that accurate speed control algorithm can effectively reduce the power consumption of the motor, at the same time ensure the performance of ABS control system.