Abstract: A power supply control is disclosed which performs in conjunction with an a.c. source as may be provided by a utility line input. This line input is directed through a converter which reflects or mirrors an a.c. signal into the line input mimicing it in all aspects except that of amplitude. The opposite side of the bi-directional device is coupled to a node connection which further is coupled to an energy reservoir present as a rechargeable storage battery. An output converter device serves to develop a desired a.c. output employing the energy at the node connection. Energy transfer into the node is provided by controlling the amplitude of the input converter such that it is slightly less than that of the input utility. The apparatus is modular in design such that it may assume a variety of configurations employing either a.c. or d.c. node connections.

Abstract: Power treatment apparatus of a UPS variety which includes a central node to which is coupled an a.c.-to-d.c. converter or conversion device, the a.c. side of which is connectable with line power and the d.c. side of which is coupled with the node. The node additionally is coupled to an output d.c.-to-a.c. converter or conversion device, the a.c. side of which is connectable with a load. Additionally, the node is coupled to a d.c.-to-d.c. converter which operates bidirectionally in conjunction with a rechargeable battery supply. The latter conversion device includes an inverter, the d.c. side of which is coupled to the battery and the a.c. side of which is coupled through a voltage boosting arrangement with a synchronous rectifier. A control protocol is developed for start-up procedures wherein the d.c./d.c. inverter is enabled only following a preliminary start-up evaluation procedure including power supply monitoring.

Abstract: An electronic signal proportional to Icos.theta. for an induction motor is substantially proportional to the mechanical power output of the motor. This signal is detected by rectifying a signal which is an analog of motor current in phase with the motor voltage and time averaging the rectified signal. Comparing the averaged signal to a reference level permits the interruption of motor current for an underload or an overload condition. The circuit permits detection of excessive ice formation on the outdoor heat exchanger of a heat pump system. The circuit is connected to the impeller drive motor which forces air across the heat exchanger and stops the motor and initiates the de-ice procedure when the ice blockage causes mechanical power delivered by the motor to deviate to a selected level.