US 6,504,732 B2 · Non-contact electrical power transmission system having function of making load voltage constant

Abstract

A transformer separable/detachable between a primary winding and a secondary winding, has a capacitor connected parallel to the secondary winding. A high-frequency AC voltage supplied to the primary winding of the transformer generates an induced voltage in the secondary winding. The secondary winding transmits electrical power to a load in non-contact manner. Either the output voltage remains constant as the output current varies, or vice versa. Taking as a first condition a fact that at the time of a maximum load, the time of the reversal of the voltage polarity of the primary winding substantially coincides with the time when an oscillating voltage of the capacitor reaches a maximum or minimum value. Taking as a second condition a fact that at the time of a minimum load, the time of the reversal of the voltage polarity of the above-mentioned primary winding substantially coincides with the time when the oscillating voltage of the above-mentioned capacitor completes one cycle. The capacitance of the capacitor is selected to satisfy simultaneously the first and second conditions. This allows the load voltage to remain constant in a load current range from a minimum to a maximum without requiring a feedback circuit.

Claims32

Dependent claims

A non-contact electrical power transmission system comprising:

a transformer separable/detachable between a primary winding and a secondary winding;
a capacitor connected in parallel with said secondary winding of said transformer;
an output terminal on said secondary winding side;
said output terminal being connectable to a load;
a high-frequency AC voltage supplied to said primary winding induces an induction voltage to be generated on the secondary winding by the electromagnetic induction action, whereby an electrical power is supplied to a load connected to said output terminal;
said voltage supplied to said load is substantially constant either while said load current varies, or said load varies;
in a first condition, at a time of a maximum load (load current Imax), the time of the reversal of the voltage polarity of said primary winding substantially coincides with a time when an oscillating voltage of said capacitor reaches at least one of a maximum or minimum value;
in a second condition, at a time of a minimum load (load current Imin), the time of the reversal of the voltage polarity of said primary winding substantially coincides with the time when the oscillating voltage of said capacitor completes one cycle;
and
a capacitance of said capacitor is set to satisfy simultaneously said first and second conditions, thereby making substantially constant the load voltage in a load current range from Imin to Imax.

7 more elements

Dependencies are inferred from the claim text.

Non-contact electrical power transmission system having function of making load voltage constant

Life of this patent

Non-contact electrical power transmission system having function of making load voltage constant

Life of this patent

Abstract

Claims32