Abstract: An analog circuit provides selectable current control and power limiting for a connected load. A current control loop is combined with a voltage/power control loop to generate a current level signal via an output transistor to control current flow through a load. Current through a load is monitored with the current control loop maintaining current flow through the load at a selected value. If a selected power level is exceeded, the current is reduced by the voltage/power control loop. Voltage monitoring and feedback is used to control the operating power for a power level control operational amplifier and thereby maintain a selected power level. By providing multiple, voltage dependent gains in the voltage feedback loop, a piecewise linear approximation of a desired power curve can be obtained.

Abstract: A method and apparatus for controlling field current in an alternator maintains the alternator output voltage at a defined level and substantially suppresses transients in the event the alternator is disconnected from a load. A pair of MOS Insulated Gate Bipolar Transistors (MOSIGBT's) are connected one in series and one in parallel with the alternator field winding and current is provided to the field winding through the series connected regulator transistor as needed to maintain the alternator output voltage. The field current is auto-commutated through the parallel connected transient suppression transistor when the regulator transistor is off. When the alternator is disconnected from a load, both transistors are switched off in a controlled manner to discharge the field winding energy at a high voltage and at an accelerated rate within the parallel connected transistor.

Abstract: A digital energy meter for providing energy measurements of nonsinusoidal waveforms. Voltage and related current components of a digitally sampled waveform are multiplied to form a product representative of instantaneous power. The products are summed or accumulated over a first time period, and the sums then accumulated over a second time period to form a second sum representative of total power over the second time period. An energy measurement is then obtained by an algorithm which requires only a simple division by a power of two.