초록 ▼

Secondary resonant pickup coils (102) used in loosely coupled inductive power transfer systems, with resonating capacitors (902) have high Q and could support large circulating currents which may destroy components. A current limit or "safety valve" uses an inductor designed to enter saturation at p

Secondary resonant pickup coils (102) used in loosely coupled inductive power transfer systems, with resonating capacitors (902) have high Q and could support large circulating currents which may destroy components. A current limit or "safety valve" uses an inductor designed to enter saturation at predetermined resonating currents somewhat above normal working levels. Saturation is immediate and passive. The constant-current characteristic of a loosely coupled, controlled pickup means that if the saturable section is shared by coupling flux and by leakage flux, then on saturation the current source is terminated in the saturated inductor, and little detuning from resonance occurs. Alternatively an external saturable inductor (1101, 1102) may be introduced within the resonant circuit (102 and 902), to detune the circuit away from the system frequency. Alternatively DC current may be passed through a winding to increase saturation of a saturable part of a core. As a result, a fail-safe pickup offering a voltage-limited constant-current output is provided.

대표청구항 ▼

1. An apparatus for controlling an inductive power transfer pickup for use in a loosely coupled inductive power transfer system, the pickup collecting power in the form of a current source from a magnetic flux surrounding a primary conductor upon energizing the primary conductor with alternating cur

1. An apparatus for controlling an inductive power transfer pickup for use in a loosely coupled inductive power transfer system, the pickup collecting power in the form of a current source from a magnetic flux surrounding a primary conductor upon energizing the primary conductor with alternating current at a system frequency, wherein the pickup comprises means for controlling an output voltage or output current at a value above a working range of said output voltage or output current, for safety purposes, and wherein the pickup is a resonant circuit which is resonant at the system frequency, wherein the pickup comprises passive means for limiting the amount of a resonating current circulating in said pickup at less than a predetermined maximum amount, said passive means comprising at least one saturable inductor having a core, wherein at least a portion of the at least one saturable inductor exhibits an onset of saturation within the core at or above a selected current so that the onset of saturation within the core changes the resonant frequency of the pickup and so causes the tuning of the pickup to deviate from the system frequency, thereby reducing the effectiveness of the collection of power and so causing the amount of the current entering the resonant circuit to be reduced.