2017 Volume 25 Issue 4 Pages 395-402
Externally coupled transcutaneous energy transmission systems (ECTETS) can supply energy to implantable ventricular assist devices wirelessly. However, the magnetic field strength induced by this system at a frequency of 2 to 4 MHz exceeds the acceptable limit guideline provided by the International Special Committee on Radio Interference (CISPR 11). To reduce the emitted magnetic field strength, the leakage inductance of the secondary coil is cancelled by a resonance capacitor, which is inserted between a secondary coil and a rectifier circuit. An equivalent circuit of ECTETS is used to determine the capacitive value. DC-DC energy transmission efficiency and the emitted magnetic field strength of the prototype ECTETS were measured without and with resonance capacitance. The results indicated that the transmission efficiency could be increased from 79.3% to 84.0% and the emitted magnetic field strength could be reduced from 16 dBµA/m to 5.6 dBµA/m at 2.74 MHz by introducing a resonance capacitor.
