The Design And Theoretical Modeling Of The Planar PCB Coil Current Transformer

The current measurement plays a very important role in many academic research and engineering application areas, at the same time in the power system industry, the protection of measuring current, over-current monitoring, energy metering, smart grid control and many other areas the measurement of the current has an important impact. Its reliability and accuracy of the power system is a necessary means to ensure the safe and reliable operation.The traditional current transformer has many problems exposed in weight, volume, cost insulation, responsiveness, and many other aspects about the measurement bandwidth. So the new electronic current transformers based on electronic technology gains more and more people’s attention. Based on the principle of magnetic coupling, we propose a new way of the current measuring, and we design a new method of the non-contact measuring the electrical equipment. And the main works in the following areas:(1) By studying the relationship between the transmission line current and the magnetic field around it, we proposed a new way by magnetic coupling principle for current measuring power system transmission line. Based on the basic principles of measuring current transformer core coil, we proposed the inverted tandem structure, and analyze the working status of the sensor, at the same time we chose the suitable transformer mode power system applications and lay the foundation for the transformer design.(2) Through electromagnetic field analysis software Maxwell, we found mathematical model of the coil and analysis the relationship of the PCB and wire hollow coil in position, we analysis the influence of various parameters about the sensor, and analysis the anti-interference of the sensor. Through the selection of parameters, we designed PCB hollow coil sensor. Modeled by MATLAB, we study amplitude-frequency characteristics of the sensor and its characteristic harmonic and analysis the transient characteristics and the steady characteristics of the coil.(3) Based on PCB coil sensor, the sampling circuit is designed, including an integrator, amplifying filter circuit, and the circuit board for the interference problem, various measures cabling interference. For the sensor signal acquisition and subsequent processing and testing.(4) We built a test platform for the sensor experimental verification. Through the steady-state characteristics of the sensor and the switching operation of the test, to verify the dynamic response. By contrast with the sensor and conventional electromagnetic current transformer, we realized to verify the linearity of the sensor. The sensors can quickly reflect changes in transmission line current and meet the power system intelligent current measurement, automation needs.