Method for regulating TETS power transfer

A method in an external power transmitter of an implanted medical device system, the method comprising:

• determining a current in an external coil of the external power transmitter;
• multiplying the current by a supply voltage to determine a power delivered to the external coil;
• controlling the power delivered to the external coil by adjusting the current in the external coil;
• and
• adjusting the power to account for resistive losses in the external coil.

A current control loop in an external device of an implanted medical device system, the current control loop including:

• an H-bridge circuit configured to output a current to an external coil of the external device;
• processing circuitry configured to:
• determine the current to the external coil based on a current output of the H bridge circuit;
• multiplying the current by a supply voltage applied to the external coil to determine a power delivered to the external coil;
• and
• controlling the power delivered to the external coil by adjusting the current in the external coil, the adjusting being by controlling a pulse width modulation (PWM) duty cycle of the H-bridge circuit in response to the determined current;
• and
• a current proportional integral derivative (PID) controller configured to control the PWM duty cycle of the H-bridge circuit.