Principle of a mathematical similarity of the converter control systems

The invariant control systems of PWM (pulse-width modulation) converters are discussed. Such structures not only form control pulses, but also ensure the stabilization of the given output quantities (such as voltage, current or certain time interval) even in the open control systems. This property of invariant control systems is obtained due to the carrier voltage which has a more complicated form than that usually used in PWM systems, i.e., linear (triangular) form. In order to emphasize this new approach, we call this kind of regulation, mathematical similarity. The general principle of creation of such a carrier voltage is formulated. Examples of specific invariant PWM systems of a control rectifier, a DC-DC converter in continuous and discontinuous operating mode, the power factor corrector and the resonant inverter are presented.