The utility model discloses an isolated form broad width voltage regulator, including first converter, the second converter, third converter and power frequency isolation transformer, input voltage inserts the input of first converter, the output of first converter is connected with power frequency isolation transformer's high -pressure side winding, power frequency isolation transformer's low tension side winding respectively and the second, the third converter is connected, the first output of second converter is as output voltage's one end, the second output of second converter and the second output of third converter are connected, the first output of third converter is as output voltage's the other end, input voltage US and offset voltage UC1, UC2 carries out the vector stack, produce output voltage U0. The utility model discloses contactless, stepless, the sinusoidal wave power electronic voltage regulator of broad width, the stabiliser that have that frequency transformer keeps apart, be applicable to single, the three -phase system of different capacity grades, high performance -price ratio, etc.