Aircraft Electric Brake Control System Research And Design

The electric braking system, in which the electro-mechanical actuator(EMA) and the digital controller replace the hydraulic actuator and analog controller respectively compared with the traditional braking system, improves the braking performance greatly. Base on the operation principle of the electric braking system, a kind of digital control system with TMS320F240 as its core, is presented. Both the hardware and software of the system are introduced in detail, and the experimental results are analyzed in the end.The anti-skid control strategy based on slip ratio, the structure of the EMA and the controller, the control strategy of Brushless DC machine (BLDCM) which is the core of the actuator are introduced briefly. Based on the dynamic mathematic model of the braking process, the non-linear and time-varying factor is analyzed, and the Parametric Fuzzy Self-regulating PID Algorithm is proposed in order to control the slip ratio at the optimal point. The algorithm performs excellently in simulaion. With lots of integrated modules in TMS320F240, speed detecting circuit, current detecting circuit, serial communication circuit are conveniently constructed. GAL16V8D is employed to deal with the BLDCM rotor position signals and the other logic signals. The BLDCM drive circuit is mainly composed by Three-Phase Full Bridge Inverter and gate driven IC IR2130 with its peripheral circuit. A three loop control strategy, with current loop as the inner one, braking moment loop as the outer one, and slip ratio loop as the outermost one, is applied here. PI algorithm is used in the current loop. PID algorithm with different parameters when increasing and decreasing the braking moment is used in the braking moment loop. The Parametric Fuzzy Self-regulating PID Algorithm is used in the slip ratio loop.The experimental results indicate that the electric braking system is able to provide desired braking pressure fast and precisely. The joint test with the aircraft simulator reveals that the system works robustly and the performance on braking time and braking efficiency are excellent.