Design Of A Current Sensor Based On Bidirectional Saturated Principle And Its Application Research

Power electronic technology and its actual application requirements promote each other,which makes them develop a lot.The smart grid,renewable energy,electric cars and other emerging markets promote the further development of power electronic technology.Modern power electronic technology regards the high frequency as its development direction,which has many advantages.However,one of the follow-on problem is that the difficulty for current measurement has increased.Complicated current waveform tends to exist in high power and frequency power electronic devices.The complicated current waveform may include dc and low-frequency components and high frequency components whose frequency may be as high as more than tens of kilohertz.At the same time,high frequency power electronic devices tend to work in high temperature environment.It has been a difficult problem for the precise detection of complicated current waveform measurement under high temperature condition.In this paper,a novel current sensor is proposed,which makes the measurement for complicated current waveform under high temperature condition come true.The prototype and experimental research were performed depending on the analysis in theory and simulation.Specific work is as follows:1.The structure and principle of the proposed current sensor are analyzed in detail.The current sensor consists of a current probe,a sensing signal processing circuit,a feedback control circuit,and an analog-to-digital converting circuit(ADC).In the proposed sensor,only one magnetic core with secondary winding wound around it is used for complicated current waveform measurements.The induced current signals in the secondary winding flow into the sensing signal processing circuit,which makes the feedback control circuit work.Then the measurement results would be calculated by computer through ADC.2.VITROPERM 500 F was used as the new magnetic core material,and the designed sensor was based on bidirectional saturated fluxgate,which makes the novel current sensor has great temperature performance.In order to broaden the measurement range and frequency,without changing the original measurement circuit and the structure of probe,the time scale flux-gate and current transformer are applied for low frequency and current and high frequency current measurements.3.Finite Element Analysis(FEA)was performed on the proposed sensor,through which the measuring range has been known: the measurement range of bidirectional saturated principle is 0.04~50A;and the range of time scale is 0~0.04 A.The addition of feedback circuit effectively improved the magnetic saturation of magnetic core in high frequency ac application.4.A prototype of the proposed current sensor was designed based on the analysis and simulation results.The work concludes the choice of the material and size of the sensor and electron device of the circuit,and the design for the measuring system.The prototype of the proposed current sensor was also tested to know the measuring range,the frequency response,the repeatability,the temperature performance of the designed current sensor.As the requirements for complicated current waveform measurement under high temperature condition increase,the proposed current sensor in this paper has promising application prospects.