Abstract: A battery charging system that may advantageously be used to directly charge a battery of a spacecraft, for example. The battery charging system permits charging of the battery without the use of power conditioners or dedicated charging arrays. Primary and secondary solar array strings are coupled by way of a shunt regulator circuit to a power bus, such as a power bus of the spacecraft. A shunt regulator circuit is coupled to the secondary solar array string and to the power bus. Charge control relays are coupled between the secondary solar array string and the battery. A computer is coupled to the shunt regulator circuit and to the charge control relays. Current from the secondary solar array string is used to charge the battery when the charge control relays are closed. If the computer determines that the battery is fully charged, the charge control relays are commanded open and current flows to the power bus unless shunted by the shunt regulator circuit.

Abstract: A spacecraft power system having an increased number of battery cells that is charged to the battery's full capacity, which exceeds a predetermined maximum voltage allowed by a bus. The battery can be disconnected from the bus during charging. The battery is then partially discharged to accommodate the bus before being reconnected. This provides a reduced voltage range experienced by the bus, as the minimum battery voltage is increased by the increased number of cells. A tap is provided to supply the bus with power when the battery is disconnected from the bus, and when a solar array powering the bus fails to supply current to the bus.

Abstract: Disclosed is a method for operating a communications signal transmitter and apparatus for carrying out the method. The method includes the steps of receiving a communications signal; sensing an amount of user demand; adjusting an output of a power supply that supplies operating power to a communications signal transmitter amplifier in accordance with the sensed demand so as to increase the output of the power supply when the sensed demand increases and to decrease the output of the power supply when the sensed demand decreases; and amplifying the received communications signal with the communications signal transmitter amplifier.

Abstract: Disclosed is a method for operating a communications signal transmitter and apparatus for carrying out the method. The method includes the steps of receiving a communications signal; sensing a signal strength of the received communications signal, the signal strength being indicative of the current user demand; adjusting an output of a power supply that supplies operating power to a communications signal transmitter amplifier in accordance with the sensed signal strength so as to increase the output of the power supply when the sensed signal strength increases and to decrease the output of the power supply when the sensed signal strength decreases; and amplifying the received communications signal with the communications signal transmitter amplifier. The step of sensing may include a step of subtracting a noise component from the received communications signal.

Abstract: An electric power regulator circuit for discharge of a spacecraft battery is employed for powering a load with energy stored in the battery. In order to produce a simplification of circuitry with reduction in the total number of components, the regulator circuit has two loops which share a common inductor. In a first loop, the inductor is serially connected with a gate, in the form of a first field effect transistor (FET) connected to the battery. The second loop includes the inductor with a series connection via a diode or a second FET to a capacitor which charges to feed the load. The load is serially connected via a current monitor between terminals of the capacitor, the monitor serving to sense the presence of short circuit current. The first FET is pulse-width modulated by a modulator operating in response to voltage sensed across the capacitor.

Abstract: A multi-slice power converter (10) employs a digital circuit (22) to generate phase-delayed pulse width modulated (PWM) signals, which results in the duty cycle of the PWM signals having only a certain number of possible values. The quantization of the duty cycle is shown to result in two types of instabilities which are unique to power converters having a digital control loop, in addition to the conventional analog-type of instabilities. This invention provides novel methods and apparatus for stabilizing the digital control loop of the power converter through the use of a periodic dither signal having a frequency that is less than the PWM frequency and greater than a bandwidth frequency of the converter. The dither signal functions to effectively increase the number of possible duty cycles by a factor given by the ratio of the dither frequency to the bandwidth frequency.

Abstract: An interleaved power converter is constructed so as to substantially equalize the power output of individual converter slices or phases. In an embodiment of the invention an interleaved power control system (110) includes a power bus (114) having a battery (116) coupled thereto and a plurality of slices (112) operating in a phased relationship with one another for causing the battery to source current to the power bus or to sink current from the power bus. Each of the slices includes an inductor (L) that is switchably coupled to the power bus and a controller (146) for controlling the switching of the inductor. The switching of the inductor is controlled as a function of (a) a difference between a magnitude of a voltage potential (V.sub.B) of the power bus and a predetermined voltage potential magnitude (Voltage Setpoint); (b) a difference between a magnitude of a current flowing through the power bus (I.sub.

Abstract: A bilateral power converter (10) for a satellite power system comprises a battery (12), an inductor (14), a switching means (18, 20), and a controller (16). The battery (12) preferably has a first and second terminals. The inductor (14) is coupled to the first terminal of the battery (12) and the switching means (18, 20). The switching means (18, 20) selectively couples the second end of the inductor (14) to a bus (28) or to ground ill response to a control signal. The controller (16) monitors the bus (28) voltage, current flow to the battery (12) and the current flow through the switching means (18, 20). The controller (16) also receives control signals from the satellite's computer (13) and automatically regulates the voltage on the bus (28) by adjusting the duty cycle of the signal output by the controller (16) to the switching means (18, 20).

Abstract: A non-intrusive DC current monitor is presented which emulates the theoretical operation of an AC transformer. A conductor, carrying the current to be measured, acts as the primary of a DC current transformer. This current is passed through the center of a secondary coil, and core positioned thereabout, and produces a magnetic flux which induces a current in the secondary proportional to the current flowing in the primary. Means are provided to periodically "reset" the transformer core such that the measurement inaccuracies associated with core saturation are obviated. A reset current is caused to periodically flow through the secondary coil which produces a magnetic flux oppositely polarized to the flux created by the current in the primary, thus allowing ongoing measurements to be made.

Abstract: A flat panel liquid crystal display for use in providing single or multi-color display images. The display comprises one or more ultraviolet light sources, a light pipe assembly which includes a plurality of liquid crystal cells that may be addressed via an array of transparent row and column electrodes, and a viewing screen having a plurality of phosphor elements that are located in close proximity and in registry with respective liquid crystal cells. Those phosphor elements and only those phosphor elements that are associated with liquid crystal cells that are in their scattering states are illuminated to form the image to be displayed.