A Transcutaneous High-Efficiency Battery Charging System with a Small Temperature Increase for Implantable Medical Devices Based on the Taguchi Method

With the rapid development of science and technology in recent years, medical equipment is gradually being implanted in human bodies to allow patients to lead normal lives. Implantable medical devices must function in the body for long periods of time; hence, efficient rechargeable power sources must be developed to non-intrusively recharge these devices. In the charging process, implantable medical devices will damage the surrounding tissue due to the resulting heat generation. In order to enhance the charging efficiency and decrease the temperature variation, a 200-mAh Li-polymer battery was charged by a multistage sinusoidal current with the minimum-ac impedance, and an optimal rapid-charging pattern was identified by the Taguchi method. Experiment results showed that in terms of charging efficiency and battery and tissue temperature control, a multistage sinusoidal current with the minimum-ac-impedance frequency performed best compared with constant current (CC), pulse current, and constant current constant-voltage (CC-CV) charging strategies. In terms of battery temperature variation, compared to the above-mentioned three charging methods, the multistage sinusoidal current method are improved charging temperatures about 1.34 °C, 1.53 °C, and 1.71 °C, respectively; in respect to charging efficiency, efficiency improved about 5.52%, 17.4%, and 5.37%, respectively.