Research Of Unilateral Axle Counting Sensor Based On Electromagnetic Induction Principle

Axle counting equipment is the basic equipment for railway signal detection, which plays a key role in the safety of railway operation. It is always used to judge whether the railway track section is idle or occupancy by detecting the axle. The axle counting equipment includes the axle sensor, the evaluation board and the axle plate. The axis sensor is the core of the axle equipment. The performance of the axle sensor determines the accuracy and reliability of the axle detection immediately. Bilateral axis sensor is the mainstream equipment in our country. But it has many matters, such as delicate structure, inconvenient installation, high cost, and so on. In this paper, a unilateral axis sensor is designed which is based on the principle of electromagnetic induction. Its structure is simplified. Its principle is improved. The safety of railway operation has been effectively improved.In this paper, we first analyze the functional requirements of unilateral axis sensor. Designing scheme based on the principle of electromagnetic induction according to the functions needed to achieve. Construct ing the mathematical model of the electromagnetic field around unilateral axis sensor and deriving the equations of the electromagnetic field around it. Analyzing the working principle of the sensor and discusses the factors what influences the distribution of the electromagnetic field around it.Secondly, design of the unilateral axis sensor, including hardware circuit and device. Researching circuit design principle and calculating circuit parameters. The hardware circuit consist of excitation circuit and induction circuit. Excitation circuit contains oscillating frequency dividing circuit and power amplifying circuit. Induction circuit contains frequency selective circuit and amplifying circuit. Determining the size, material and electrical parameters of the induction coil and field coil, and the material and size of the outer skin of the sensor.Then, study of the magnetic field of the unilateral axle counting sensor in the finite element analysis software. Determining the size of the wheel and steel rail. Establishing the 3d simulation model of the sensor. Analyze the influence to the induction electromotive force and the magnetic field when the frequency of the excitation signal is changing.Finally, getting measurement data according to the experimental platform that we built. Changing the space position between unilateral axis sensor and steel rail and measuring the induced electromotive force. Changing the exc itation frequency and measuring the induced electromotive force. Changing the parameter of the field coil and induction coil and measuring the induced electromotive force. Verify the validity and accuracy of the simulation. Determine the optimal installati on position and so on.