US 11,387,690 B1 · Self-aligning wireless power transfer system that switches power current into aligning electromagnets

Abstract

A wireless power transmitter has electromagnets and a transmitter coil mounted on a moving plate. Current in the main DC circuit is switched into the electromagnets by transistors that control the amount and direction of current through the electromagnets to control the strength and polarity of electromagnetic fields generated by the electromagnets. A controller initially drives a high gate voltage onto transistors to cause the electromagnets on the transmitter to generate a maximum attractive force with magnets on the receiver, causing the moving plate to move the transmitter coil into closer alignment with the receiver coil. A power factor is measured on both receiver and transmitter to estimate the power transfer efficiency. The controller then reduces the gate voltage by a step size and the power factors are measured again. The gate voltage continues to be adjusted to optimize the power transfer efficiency until reaching a maxima.

A self-aligning wireless power transmitter comprising:

a movable mount;
an electromagnet fixed to the movable mount;
a transmitter coil fixed to the movable mount, the transmitter coil generating a power-transferring electromagnetic field that transfers power to a receiver coil on a receiver when the transmitter coil and the receiver coil are aligned;
a transistor that switches a first current into the electromagnet in response to a gate voltage applied to the transistor;
a controller that generates the gate voltage with a voltage that is adjusted to adjust a strength of an aligning electromagnetic field generated by the electromagnet to adjust a force applied to the movable mount by the aligning electromagnetic field generated by the electromagnet to move the movable mount to adjust an alignment between the transmitter coil and the receiver coil;
and
a power converter that receives the first current and a first bypass current that bypasses the electromagnet, the power converter generating a second current from the first current and the first bypass current;
wherein the second current is applied to and passes through the transmitter coil to generate the power-transferring electromagnetic field;
wherein the first current passes through the electromagnet to generate the aligning electromagnetic field,
wherein the first current powers the electromagnet and also at least partially powers the power converter to power the transmitter coil to transfer power to the receiver,
wherein the power converter is a Direct Current (DC)/Alternating Current (AC) inverter;
wherein the first current through the electromagnet is a DC current;
wherein the second current through the transmitter coil is an AC current;
wherein the electromagnet is powered by DC and the transmitter coil is powered by AC current;
an AC/DC converter that receives AC power from an AC power source, and generates a DC output that includes the first current and the first bypass current that are DC;
wherein alignment is performed by the DC current passing through the electromagnet;
wherein wireless power transfer to the receiver is performed by the AC current passing through the transmitter coil;
wherein the electromagnet and the transistor comprise a plurality of switchable elements,
wherein each switchable element in the plurality of switchable elements comprises:
an element input;
an element output;
an element electromagnet having a first terminal connected to a first element node and a second terminal connected to a second element node;
a first element transistor having a gate receiving a first gate voltage from the controller for controlling current through the first element transistor between the element input and the first element node;
a second element transistor having a gate receiving a second gate voltage from the controller for controlling current through the second element transistor between the element input and the second element node;
a third element transistor having a gate receiving a third gate voltage from the controller for controlling current through the third element transistor between the first element node and the element output;
and
a fourth element transistor having a gate receiving a fourth gate voltage from the controller for controlling current through the fourth element transistor between the second element node and the element output;
a first switchable element and a second switchable element connected in series on a positive power line between the AC/DC converter and the DC/AC inverter;
and
a third switchable element and a fourth switchable element connected in series on a power-return line between the AC/DC converter and the DC/AC inverter;
whereby the electromagnet is integrated into a power circuit that powers the power converter to power the transmitter coil.

28 more elements

Self-aligning wireless power transfer system that switches power current into aligning electromagnets

Life of this patent

Self-aligning wireless power transfer system that switches power current into aligning electromagnets

Life of this patent

Abstract

Claims12