| Abstract [eng] |
The aim of this project is to propose methods to measure transmitted power to receiver when measurements are performed only in the transmitter circuit in wireless power transfer systems. It is relevant because having the ability to estimate the transmitted energy only in the transmitter side can significantly costs because the metering equipment does not need to be installed on the receiver side. Measurements of the transmitted power on the transmitter side can be used to assess the efficiency of the transmitted power to the receiver, as well as to keep records of how much power is transmitted. The project proposes three methods that can be used to determine the power transmitted to the receiver by performing measurements only on the transmitter side. The first method does not require to know any system parameters. For the second method it is necessary to know the exact values of the parameters of the components in the resonant circuit: inductances of the coils, resistances, capacitances of the capacitors. This method requires to change the frequency of the transmitter. The third method requires to know the same component parameters as the second method. The frequency is changed, and another capacitor is connected to match the transmitter side to the new resonant frequency. First, simulations were performed in MATLAB / SIMULINK environment and relative and absolute errors were obtained for each method. Simulations were performed when the load on the receiver is linear (resistor) and nonlinear (diode bridge, capacitor, resistor). Simulations were performed when the load was changing, the mutual inductance was fixed, and when the mutual inductance was changing, the load was fixed. During the simulation, it was found that all three methods can determine the power in the receiver. The results are presented in graphs and tables. The simulation found that all three methods can determine the power of the receiver. The results are presented in graphs and tables. First, the electrical circuit diagram of the transmitter was designed. Then the printed circuit board was designed. Transmitter and receiver coils were fabricated, and resonant circuits were assembled and tested. After assembling the real system and writing the software code in MATLAB environment, experimental tests were performed, which were the same like in simulations. Experimental tests have shown that all three methods can determine the power in the receiver. The results are presented in graphs and tables. Conclusions and recommendations are presented. The experimental results are worse than the modeling. This may have happened because the second and third methods need to know the exact values of inductances, capacitances, and resistances. All parasitic inductances and capacitances could affect the accuracy of the obtained results. Also, the accuracy of the results could be compromised because an oscilloscope that had only an 8-bit analog code converter been used for the measurements. Possibly using a higher number of bits in the analog digital converter would give more accurate results. |
