Abstract: A constant-current controller that supplies a constant current to an inductive load. This controller comprises an electric control circuit module. The electric control circuit module comprises a primary switch and a secondary switch. During a time interval in which the primary switch is closed (ton), the secondary switch is open and the voltage across the inductive load is equal to the source voltage (Vs). At time ton until the end of a time interval (T), zero volts appears across the inductive load. During this interval, current continues to flow as supplied by the energy stored in the inductance. The periodic current in the inductive load becomes constant with a sufficiently large PWM switching frequency and is dependent upon the parameters of the control circuit and the duration of ton.

Abstract: A power control circuit assembly for an electric door lock comprises a load control circuit module configured to distribute a DC operating voltage to power an electromechanical door latch mechanism and its associated access control device. An energy storage device such as a rechargeable battery is coupled to the load control circuit module and is configured to deliver a DC voltage to the load control circuit module wherein the DC energy storage device voltage supplies the DC operating voltage. A rectifier is configured to receive an input AC voltage and convert the input AC voltage to an input DC voltage. The input DC voltage is adapted to deliver an energy storage device recharge voltage. An energy storage device voltage detection module is configured to interrogate a DC voltage supplied by the energy storage device.

Abstract: A speed controller for a three phase induction motor using sliding mode control to generate estimates of stator current and rotor flux to control motor speed. The controller receives only the actual operating speed and the desired operating speed as input signals. The controller establishes linked non-linear hyperplaces containing the operating points of each phase and coerces the operating points to move along the line of intersection. A change in operating conditions causes a change in the power supplied to the phase terminals.