Control of passive electric systems powered by energy harvesting

A method for operating an electromechanical lock, the method comprising:

• collecting ambient energy using an energy harvesting circuit and using the collected ambient energy to charge a buffer capacitor with a capacitor voltage;
• via cyclical ON/OFF control, alternatingly connecting an electric motor to the buffer capacitor in a discharging phase and disconnecting the electric motor from the buffer capacitor in a charging phase;
• wherein alternatingly connecting and disconnecting the electric motor and the buffer capacitor is performed until a work output of the electric motor reaches a desired target level or until an end of an nth discharging phase, n being a predetermined number;
• and
• wherein durations of the charging phase and the discharging phase are controlled such that the capacitor voltage stays above a minimum supply voltage of the electric motor such that the electric motor moves a latch of the electromechanical lock;
• wherein the cyclical ON/OFF control includes implementation of multiple ON/OFF control cycles, each respective ON/OFF control cycle of the cyclical ON/OFF control cycles including:
• i) for an ON portion of the respective ON/OFF control cycle, activating switch circuitry to an ON-state to convey the capacitor voltage to the electric motor, and ii) for an OFF portion of the respective ON/OFF control cycle, deactivating the switch circuitry to an OFF-state to prevent conveyance of the capacitor voltage to the electric motor;
• wherein the magnitude of the capacitor voltage stored in the capacitor is controlled to be greater than the minimum supply voltage during the ON portion of the respective ON/OFF control cycle;
• and
• wherein the magnitude of the capacitor voltage stored in the capacitor is greater than the minimum supply voltage during the OFF portion of the respective ON/OFF control cycle.

An apparatus comprising:

• wireless receiver hardware operative to wirelessly receive energy and store the received energy in an energy storage device to produce a supply voltage;
• and
• a controller operative to:
• i) monitor a magnitude of the supply voltage stored in the energy storage device;
• and
• ii) during cyclical ON/OFF control of supplying power from the supply voltage to a mechanical load, prevent the magnitude of the supply voltage from falling below a voltage threshold level, the magnitude of the supply voltage applied to the mechanical load above the voltage threshold level causing physical movement of the mechanical load;
• wherein the voltage threshold level is a first voltage threshold level;
• wherein the energy storage device is a capacitor;
• wherein the cyclical ON/OFF control includes implementation of multiple ON/OFF control cycles;
• wherein the controller, for each respective ON/OFF control cycle of the multiple cyclical ON/OFF control cycles, is operative to:
• i) for an ON portion of the respective ON/OFF control cycle, activate switch circuitry to an ON-state to convey the supply voltage to the mechanical load;
• and
• ii) for an OFF portion of the respective ON/OFF control cycle, deactivate the switch circuitry to an OFF-state to prevent conveyance of the supply voltage to the mechanical load;
• wherein the magnitude of the supply voltage stored in the capacitor is controlled to be greater than the first voltage threshold level during the ON portion of the respective ON/OFF control cycle;
• and
• wherein the magnitude of the supply voltage stored in the capacitor is greater than the first voltage threshold level during the OFF portion of the respective ON/OFF control cycle.