Wide-Range Self-Excited Bidirectional Saturated Fluxgate Current Sensor

The current sensor is an important part of the power electronic converter,with current detection and feedback functions.Among them,accurate detection of current is an important requirement for sensors.Current detection requires not only accuracy and fastness,but also good temperature stability.In view of the above problems,a new self-excited oscillating flux gate current sensor based on the principle of a bidirectional saturated flux gate is proposed.The mathematical model of the sensor is established,the design process of the sensor is given,the experimental prototype is made,and the experimental research is carried out.The specific work is as follows:1.A new current sensor measurement method is proposed,which establishes the relationship between the time difference between the first half and the second half of the excitation current and the measured current.This method can effectively cancel the drive delay and the error caused by the drift of the power amplifier.2.A method for measuring the saturation inductance of the magnetic core is proposed.Based on the principle of parallel resonance,the relationship between the equivalent inductance of the current sensor and the resonance period is obtained when the magnetic core is saturated.According to the measurement principle,the circuit is designed.Through simulation experiments,the validity of the measurement method is verified.3.The current sensor is designed,including:sensor probe,detection circuit,and excitation circuit.In the design of the probe,a nanocrystalline alloy core was selected,and its hysteresis loop was tested to analyze the loss of the sensor.The detection circuit part is mainly composed of a DSP and an e CAP module in the DSP,and the rising and falling edges of the driving signal are collected by the e CAP module.The excitation circuit consists of a voltage comparator,a DQ flip-flop,a drive circuit,and an inverter circuit.4.Develop a sensor experimental prototype to analyze the effect of the measured current on t _S,t _P,t _N and t_sat.Experiments were performed on the linearity,resolution,sensitivity,and uncertainty of the proposed current sensor at 25°C and 105°C,and the correctness of the theoretical model of the new self-excited oscillating fluxgate current sensor and the rationality of the experimental prototype design have been verified.