Research And Implementation Of Torque Sensing Control System Based On Holzer Device

Currently, electric power assisted bicycle is now welcomed by the market. People pay special attention to the health, environmental protection and other aspects of the problem when pursuing convenient travel. Intelligent electric bicycle is able to realize intelligent control when compared with the traditional electric bicycle. In some special situation, such as drag, uphill and so on, the rider need to use a lot of man-power to achieve a smooth running. The traditional electric bicycle can not adjust the output of the motor or control the output by human involvement due to the design defect. This approach affects the life of motor and battery. On the contrary, intelligent electric power bicycle can detect the force state of rider dynamically and adjust the output power of the motor. This allows the rider to save effort in the situation of drag or uphill.The core equipment of intelligent electric power bicycle is the torque sensor. The torque sensor is able to detect the signal of the change of rider force, and then control the motor power through real-time processing algorithm. However, the existing electric bicycle torque sensors collect the analog signal with few amounts, low speed and low sensitivity, which makes the motor output power instable and the booster effect unobvious during riding. This dissertation proposes a new torque sensor based on two pairs of hall devices. The main work of this dissertation is as follows:(1)This dissertation firstly introduces the structure design of the proposed torque sensor. The core of torque sensor is the two pairs of hall device on the inner magnetic ring and the outer magnetic ring. In order to cope with the effect of the two pairs of hall devices and enhance the detection precision, the magnetic rings are using surface magnetization, and the magnetic guide is added.(2)This dissertation gives a detailed force analysis of the electric power assisted bicycle. The torque signal conversion model is clearly analysised and the principle of the designed torque sensor is deduced. The experimental results show that the phase difference becomes stable under different pedaling frequency when the spring deformation is unchanged. Moreover, with the increase of deformation, the phase difference is also growing.(3) In order to realize the intelligent control of the output power of motor, this dissertation proposes the output power control model and the relevant control circuit based on the PID control algorithm. The control circuit includes signal acquisition, signal processing and the motor control circuit. Through lots of experiments, the optimal PID control parameters are obtained. Experiments also show that the intelligent electric power bicycle is able to output smooth power under the condition of starting and flat road. This makes the rider exert oneself with less effort.