基于单端口阻抗测量和灵敏度分析的耦合线圈参数辨识

In the wireless power transfer (WPT) technique, the parameters of the magnetic coupling coil circuit model are the key parameters for the design of impedance compensation circuit, the calculation of power loss, and the research on the frequency characteristics. In this paper, the off-line identification method for the parameters of magnetic coupling coil model is proposed based on the sensitivity analysis of single port and the principle of optimization. The coils are connected into a single port network, and then the objective function is constructed to get the minimum sum of squares of the modulus of complex impedance error, according to the measurement results of the impedance analyzer and the theoretical results calculated by the model parameters. The sensitivities of the impedance to the parameters are used to calculate the searching direction of the objective function. The unit current source phasor excitation method is also proposed to find the sensitivities by means of the two-port T type equivalent network. According to this method, the sensitivities of the impedance to different parameters can be determined only by the square of the current phasor or the voltage phasor of the elements, or by their multiplication, when the unit current source phasor is applied to the circuit. That is much easier than deducing the analytical expression of impedance and its partial derivative. In the experimental research, the coupling coils are set under the seawater tank, the electromagnetism effects of the seawater, the skin effects, as well as the internal reactance of the coils are considered in the parameter identification.