An inductive-power-transferred LED driver with constant-current compensation tanks

The inductive-power-transferred (IPT) light emitting diode (LED) lighting system is convenient, flexible and safe in many applications. To improve the transfer efficiency, compensation tanks are introduced. But output characteristics of the compensated IPT system are complex, having relations with transformer parameters, tank topologies and parameters, switching frequency, and load values. It is known that the equivalent resistances of LED loads readily vary with temperature. Moreover, the loosely coupled transformer is hard to design due to non-uniform magnetic field. These problems challenge the design of an IPT LED driver to provide the required LED current directly. To solve them, this paper proposed an IPT LED driver with the constant-current compensation tank, which decouples the effect of load resistance. With well-designed transformer and compensation tanks, the IPT LED driver can directly generate the required LED current via duty cycle control at the fixed frequency. This paper also gave design steps under the given specifications. The analysis, implementation and verification were detailed in this paper.