Pulse width modulated DC voltage converter with regulated output - has control signal dependent on current and sawtooth reference voltage permitting output pulses greater than half period

摘要

The d.c. voltage converter employing pulse width control with current and output voltage feedback, and giving a controlled output voltage, suffers from the disadvantage that any extension of the output pulse length beyond half a period to maintain the output voltage results in instability. This deficiency is eliminated by introducing a modifying signal into the reference circuit. The output voltage is compared with a voltage comprising a constant reference (Uref), a load current dependent term (UR1), and a saw-tooth voltage in phase with the switching frequency (1/T). The modification allows a large increase in pulse width without instability, and is applicable to most pulse width modulated regulators operating at constant frequency.