摘    要

汽车电动助力转向系统(EPS)与传统的机械、液压助力转向系统相比具有转向灵敏、能耗低、与环境的兼容性好、成本低等优点。目前，在很多高端车上都装由EPS，因此，开发EPS具有很大的实际意义和商业价值。电动助力转向系统主要由控制部分、执行部分和程序这三个部分组成，控制部分主要由信号采集电路、单片机和信号发送电路组成。其中单片机是控制部分的核心部件，信号采集电路采集到的转矩和车速信号送单片机处理后，单片机再发出控制信号给信号发送电路，经过驱动电路驱动电机转动。执行部分主要由电机、减速机构和电磁离合器的组成。它起着转向辅助动力的产生，传递和中断的作用。而程序是助力控制方式的具体体现，它由控制方式和控制策略来决定。控制部分、程序、执行部分相互组合就构成了以一完整的汽车电动助力转向系统。经过组建系统调试后，得出了我们所需要的助力特性曲线，经过分析，采用的控制形式存在级变震动，为了减小震动的影响，必须增加助力曲线的数目以减小震动幅度，但是幅度必须足够的小，小到足以忽略频率的影响。

关键词：电动助力转向，单片机，助力曲线，直流电机，电机控制

ABSTRACT

Electric power steering system (EPS) has the advantage of sensitive, low energy consumption and environmental compatibility, and low cost compared with the traditional mechanical and hydraulic power steering system. At present, in many high-end vehicles are installed by the EPS, therefore, the development of EPS has great practical significance and commercial value. EPS controlled by the controller, actuator and procedures. The controller controlled by the signal acquisition, SCM, and circuit sent signals. SCM is the core components of the system, signal acquisition circuit to the acquisition of torque and speed signals sent to deal with SCM. Then, SCM sent the control signals to the signal circuit, after, driving circuit driving motor rotation.  Actuator controlled by motor, reducer, and electromagnetic clutch. It plays to the formation of auxiliary power, transmission and the role of interruption. The assistance program is a concrete manifestation of control. It is decided by the control strategies. Controller, procedures, operation each other are combination of a complete vehicle electric power steering system. After the system debugging, we need to come to the assistance of the curve. After analysis, there is a shocking when the speed changes from one state to another. In order to reduce the impact of shock, we need to increase the number of curve to reduce the rate shock, however, the rate must be small enough to neglect the impact of the frequency.

Key words： electric power steering, SCM, power curve , DC motor, motor control