The invention provides a multi-
phase variable-frequency power source. The multi-
phase variable-frequency power source comprises a self-
coupling transformer and multiple
power module units for realizing a
frequency conversion effect, wherein one primary side of the self-
coupling transformer is a three-phase winding connected with a
power grid, a
secondary side of the self-
coupling transformer is provided with two three-phase windings, each
power module unit comprises three groups of circuits, each group of circuits comprise two three-phase full-wave
rectifier circuits which are in anti-parallel, the same-phase ends of outputs of the three groups of circuits are connected with one another, bridge arms of the three-phase full-wave
rectifier circuits are controllable power devices, one primary side of the self-
coupling transformer is connected with the first group of circuits of the
power module units, and the two three-phase windings of the
secondary side of the self-
coupling transformer are connected with the second groups of circuits and the third group of circuits of the power module units. The multi-
phase variable-frequency power source has the advantages that the
frequency conversion and inversion are effectively realized, and the bidirectional flow of energy is realized; the variable-frequency power source with different phase numbers is obtained by increasing and decreasing the number of the power module units; a unidirectional
silicon controlled
rectifier is adopted, so that the circuit topology structure of a full-controlled device is changed, the manufacturing cost is greatly reduced, and the efficiency is improved; and the losses are reduced during
frequency conversion due to the adoption of the
silicon controlled rectifier, and the multi-phase variable-frequency power source is concise and reasonable in technological structure, low in cost and high in efficiency.