Impedance matching device and control method

摘要

In an impedance matching device, a storage unit stores a control value representing a load value and a value equivalent to input impedance in advance. The control value identifies inductance and capacitance values matching a predetermined impedance value by use of either a first or second matching circuit. An impedance estimation unit estimates input impedance of the power transmission antenna. The load value estimation unit estimates load value of a circuit connected to a power reception antenna and consuming transmitted electric power. A circuit selection unit electrically connects the first matching circuit, the second matching circuit, or a through circuit per the load value and the input impedance equivalent value. A control value output unit reads out the control value stored in the storage unit based on the load value and the input impedance equivalent value, and outputs the control value to the circuit selected by the circuit selection unit.

主权项

1. An impedance matching device included in a wireless electric power transmission system, the wireless electric power transmission system transmitting wireless electric power radiated from a power transmission antenna to a power reception antenna by coupling the power transmission antenna with the power reception antenna through an electromagnetic field, the impedance matching device being provided between a power transmission circuit and the power transmission antenna, the impedance matching device comprising:
an input impedance estimation unit configured to estimate an input impedance equivalent value corresponding to an input impedance of the power transmission antenna or a value equivalent thereto; a first matching circuit configured to include a first variable inductor element and a first variable capacitor element, the first variable inductor element being connected in series between the power transmission circuit and the power transmission antenna, one end of the first variable capacitor element being grounded, another end of the first variable capacitor element being connected between the power transmission antenna and the first variable inductor element; a second matching circuit configured to include a second variable inductor element and a second variable capacitor element, the second variable inductor element being connected in series between the power transmission circuit and the power transmission antenna, one end of the second variable capacitor element being grounded, another end of the second variable capacitor element being connected between the power transmission circuit and the second variable inductor element; a through circuit connected in series between the power transmission circuit and the power transmission antenna; a load value estimation unit configured to estimate a value of a load of a power circuit in which the transmitted electric power is consumed, the power circuit being connected to the power reception antenna; a storage unit configured to store control values each associated with the value of the load and the input impedance equivalent value, each of the control values corresponding to an inductance value and a capacitance value, the inductive and capacitance values needed for matching to a predetermined impedance value used by the first matching circuit or the second matching circuit; a circuit selection unit configured to electrically connect one of the first matching circuit, the second matching circuit and the through circuit based on the estimated value of the load and the estimated input impedance equivalent value; and a control value output unit configured to read out one of the control values stored in the storage unit based on the estimated value of the load and the estimated input impedance equivalent value, and to output the control value to the respective circuit selected by the circuit selection unit.