Voltage regulator, voltage regulating system and voltage regulating method

The invention discloses a voltage regulator, a voltage regulating system and a voltage regulating method. The voltage regulator comprises a transformer, a plurality of load switches and a preset load switch, wherein the transformer comprises a primary coil and a secondary coil, the primary coil comprises a first end, a second end and a plurality of groups of serially connected coils, and the plurality of groups of serially connected coils are connected between the first end and the second end; the load switches correspond to the groups of serially connected coils one by one, and one end of each load switch is connected with one group of coils while the other end of the same is connected with the first end of the primary coil. One end of the preset load switch is connected with the first end of the primary coil, and the other end of the preset load switch is connected with any point in the groups of serially connected coils. The voltage regulator, the voltage regulating system and the voltage regulating method have the advantage that the problem in the prior art that power cannot be supplied normally since power is cut off for voltage regulation is solved.