Abstract: Voltage on a DC power bus is controlled using gated fixed energy pulses. The power bus includes a bus capacitor for storing charge and can have a varying load. A battery is provided for providing electrical power to the bus through a power boost circuit including a boost switch for selectively applying a pulse of a fixed amount of energy to the bus in response to comparison of the bus voltage and a first reference voltage. The power boost circuit can include a choke coil and a timer for establishing an on time and an off time for each pulse, the on time establishing the amount of energy to be delivered to the bus, and the off time allowing the energy to be delivered to the load. A shunt path including a shunt switch can be provided for shunting energy from the bus when the bus voltage reaches a second reference voltage higher than the first reference voltage. In a preferred embodiment, the shunt path shunts energy to the battery for recharging the battery.

Abstract: A bidirectional power converter array has overall voltage feedback, an error signal generator, and plural bidirectional power converter modules. Each module of the array includes a series inductor and local feedback based upon the inductor current. Each module also has a resistive current sensor, providing wideband local feedback. A low-pass filter is coupled to the current sensing resistor to reduce switching noise. The low-pass filter also reduces the bandwidth of the local feedback signal, so interactions with the overall feedback occur, which may result in instability. A winding transformer-coupled to the series inductor generates AC signal representing high-frequency components of the inductor current, relatively free of switching noise. The AC current sample is added to the low-frequency components derived from the resistor and low-pass filter, to form a low-noise local feedback signal, with sufficient bandwidth to reduce unwanted interactions with the overall system feedback.

Abstract: A solar cell voltage regulating arrangement which is particularly advantageous for use in spacecraft includes a light valve such as a liquid crystal cell disposed before the solar cell, to thereby controllably vary the light transmission to the solar cell. A control arrangement varies the transmission of the liquid crystal to control the output voltage.

Abstract: A high efficiency, regulated DC supply combines the rectifying and a series regulating elements into one device such as a MOS FET which is gated "on" or "off" by the polarity of an AC voltage from a transformer winding. During the "on" state of the MOS FET a feedback network varies the MOS FET gate voltage as necessary to provide regulation of the DC output voltage during the "on" period.

Abstract: A voltage regulator for controlling the voltage of a bus powered by N solar cell arrays. Digital shunts are coupled to N-1 of the arrays. A linear shunt is coupled to the remaining array. Current passing through the remaining array is sensed by the linear shunt which, in response thereto, turns on and off various ones of the digital shunts to maintain the desired voltage on the bus.

Abstract: A control system to maintain a given temperature at a thruster heater resistance element coupled to a battery bus is provided by periodically disconnecting the main power to the resistance element and applying a sampling current to the resistance element to provide a voltage corresponding to the sensed resistance. The voltage representing the sensed resistance value is stored and compared with a reference voltage indicative of a given temperature. Power to the resistance element is disconnected when the sensed voltage exceeds the reference and reconnected when sensed voltage is below the reference.

Abstract: An inrush current limited power supply includes a regulator with a capacitor coupled across its input terminals. If voltage to be regulated is suddenly applied by a switch to the input terminals of the regulator, an undesirably large current surge occurs as the capacitor charges. The magnitude of the current surge is limited by a surge limiting resistor coupled in series with the switch. This limits the surge current, but undesirably causes power dissipation in the resistor during normal operation. The channel of a FET is connected across the resistor. The FET has a conductivity which is low when the gate-to-source voltage is low, for preventing large inrush current immediately after turn-on. A control voltage generator generates a control voltage by rectifying an alternating voltage, and it is coupled to the gate and source of the FET. In one embodiment, the control voltage generator is referenced to an input terminal of the regulator. In another embodiment it is referenced to output terminal.

Abstract: An electrothermal hydrazine thruster passes the hydrazine through a catalyst bed and an augmentation heater. The augmentation heater includes an electrical heating element powered by a satellite battery. A load resistance is coupled in series with the heating element to reduce the current through the electrical circuit including the heating element to a safe level. A switch coupled across the load resistance is closed bypassing the load resistance when the heating element heats up and increases its resistance value to a value that can be tolerated in the battery circuit.