Pulse-type voltage stabilizer with integral pulse-width modulation

A voltage stabilizer with integral pulse width modulation consists of a power amplifier followed by a low pass filter for the line voltage, a reference oscillator and a variable ratio frequency divider, and a pulse phase detector which performs the integral control by comparing the two incoming signals from the reference oscillator and the frequency divider respectively, and feeds the mismatch signal to the power amplifier. The operation of such a voltage stabilizer is best analyzed on the basis of a system of two equations describing respectively the state vector and the output signal of its continuous linear amplifier filter part, assuming that the latter has a constant structure, as functions of time. From these equations and the law of unipolar integral pulse width modulation are obtained the performance characteristics of the voltage stabilizer in the locking mode. The error load characteristic and the stability limits as well as the locking band of a voltage stabilizer whose continuous linear part has the simplest transfer function indicate that there is an optimum load resistance corresponding to the minimum stabilizer error. An increase of the load resistance will gradually increase the error until the locking and stabilization limit is exceeded. A decrease of the load resistance below that optimum will actuate the overload protection and thus cut out the voltage stabilizer altogether.