Precision power level control for extended range wireless power transfer

A power transmitter for wireless power transfer at an operating frequency selected from a range of about 87 kilohertz (kHz) to about 205 kHz, the power transmitter comprising:

• a control and communications unit configured to provide power control signals to a power supply external to the power transmitter for controlling a power level of a power signal configured for transmission to a power receiver, the power supply configured to configure a direct current (DC) power based on the power control signals;
• an inverter circuit configured to receive the DC power from the power supply external to the power transmitter and convert the input power to a power signal;
• a coil configured to transmit the power signal to a power receiver, the coil formed of wound Litz wire and including at least one layer, the coil defining, at least, a top face;
• and
• a shielding comprising a ferrite core and defining a cavity, the cavity configured such that the ferrite core substantially surrounds all but the top face of the coil.

A system for wireless power transfer at an operating frequency selected from a range of about 87 kilohertz (kHz) to about 205 kHz, the system comprising:

• a power transmitter including
• a control and communications unit configured to provide power control signals for controlling a power level of a power signal configured for transmission to a power receiver,
• an inverter circuit configured to receive a direct current (DC) power and convert the input power to a power signal,
• a coil configured to transmit the power signal to a power receiver, the coil formed of wound Litz wire and including at least one layer, the coil defining, at least, a top face, and
• a shielding comprising a ferrite core and defining a cavity, the cavity configured such that the ferrite core substantially surrounds all but the top face of the coil;
• and
• a power supply, the power supply external to the power transmitter, the power supply configured to configure the DC power based on the power control signals, the power supply including
• a voltage regulator, and
• a power supply controller configured to
• receive the input power signals,
• generate voltage regulation instructions for altering the DC input power, based on the power control signals, the voltage regulation instructions including voltage step up instructions or voltage step down instructions for the DC/DC convertor, the voltage step up instructions and voltage step down instructions having a step level, the step level being a change in voltage at which the voltage regulator is configured to step up or step down the DC voltage of the DC power, and
• provide the voltage regulation instructions to the voltage regulator to control a DC voltage of the DC power.