Microprocessor-Controlled Digital Shunt Regulator

A new approach to the design of power systems is presented in which a microprocessor is used as a controller for a digital shunt regulator (DSR). This approach meets the demands of future space and ground missions, i. e., high efficiency, high reliability, low weight, low volume, increased flexibility, and less development time. This approach responds to future demands by permitting realtime modification of system parameters for system optimization. This feature is especially important in the event of an anomaly. As the microprocessor need not be dedicated to the DSR, it can simultaneously be used for battery management and for charge regulator/discharge regulator control. This approach also reduces the component count, simplifies assembly and testing of the unit, results in significant time saving, and increases the reliability.     

Low-Frequency Characterization of Switched dc-dc Converters

Averaging techniques are developed to represent buck, boost, and buck-boost types of switched dc-dc converters by approximate continuous models. Simple analytical expressions in terms of the circuit components are derived for the characteristic transient and frequency responses of time-average(continuous) power-stage models for use in designing and understanding the behavior of corresponding switched power stages. Novel conclusions include the dependence of effective circuit component values upon switch duty ratio and the existence of a real positive zero in certain transfer functions. Responses from analog computer simulations of the switched and averaged powerstages agree well and, in turn, confirm the analytic predictions. High-order systems can be analyzed by the averaging technique without a commensurate increase in complexity.     

Describing Function Properties of a Magnetic Pulsewidth Modulator

An analysis is presented for the transfer functions of a particular pulsewidth modulator and power-stage subsystem that has been widely used in practical switching-mode dc regulator systems. The switch and filter are in a ?buck? configuration, and the switch is driven by a constant-frequency, variable duty-ratio, push-pull magnetic modulator employing square-loop cores. The two transfer functions considered are that with modulator control signal as input and that with line voltage as input. For ac signal,the corresponding describing functions (DF) are derived. It is shown thatcurrent-source drive to the modulator extends the control DF frequency response over that with voltage drive, and that complete cancellation of the effects of line variations can be obtained at dc, but not for ac. Experimental confirmation of the analytical results for the control DF are presented.