| Wireless power transfer(WPT)is a technology that use a non-contact method to utilize the propagation characteristics of electromagnetic waves in space thereby enables electrical energy to be transmitted across space without any medium.It has developed rapidly in recent years and is widely used in many fields,such as medical device development,transportation engineering,home electronics and underwater facilities.As the application of WPT becomes more and more close to people's daily life,its electromagnetic environment and safety issues are gradually exposed to the public's vision.In this paper,the working principle of the resonant WPT system was analyzed in detail.Using the limit element analysis method,the following research was carried out on the electromagnetic safety effects that the electric vehicle charging system have on the human body and implanted device.(1)The representative electromagnetic protection safety standards at home and abroad were analyzed,derived limit(electric field strength in space,magnetic induction intensity)and basic limit(intra-body induced electric field intensity peak,specific absorption rate)were chosen as the electromagnetic safety evaluation criterion of the WPT system.(2)The field-circuit coupled finite element numerical analysis of the resonant WPT system was completed,and then the coil models that are suitable for different output powers was constructed,In addition the applicable frequency band of the electric vehicle charging system under the premise of ensuring the maximum transmission efficiency was determined,the highest frequency is up to 1100 k Hz.The space electromagnetic field distribution around the system was studied by simulation,and the derived limit value was used as the index to calculate the safe distance under different transmission efficiency and output power conditions.(3)A human body and implanted device(cardiac pacemaker)model were constructed to simulate the peak electric field strength and the specific absorption rate of the human body at different positions of the WPT system,and compared with the basic limit to determine the safe distance between the human body and the WPT system at different frequencies and power conditions.The electromagnetic parameters of the implanted device were compared with the electromagnetic compatibility standards of the medical device.(4)The partial differential equations for temperature field were derived to achieve the mutual coupling of electromagnetic field and temperature field.Finally,the electromagnetic thermal effect of human body which implanted metal devices on the safe distance of the WPT system was analyzed. |
PDF Full Text Request