Power conversion device

A power conversion method comprising:

• generating a first voltage command having a first command phase in a first rotating coordinate system based on a first torque target value, wherein a first rotating magnetic field for driving a rotor of an induction motor is generated to rotate with the first rotating coordinate system;
• calculating a first rotation phase of the first rotating coordinate system based on a first torque target value and a rotor speed of an induction motor;
• outputting a first driving power to the induction motor based on the first rotation phase and the first voltage command;
• generating a second voltage command having a command phase in a second rotating coordinate system based on a second torque target value, wherein a second rotating magnetic field for driving the rotor of the induction motor is generated to rotate with the second rotating coordinate system;
• calculating a second rotation phase of the second rotating coordinate system based on a command phase difference between the first command phase and the command phase to reduce the command phase difference;
• and
• outputting a second driving power to the induction motor, based on the second rotation phase and the second voltage command, so that the second rotating magnetic field is in synchronization with the first rotating magnetic field.

A non-transitory memory device having instructions stored thereon that, in response to execution by a power conversion device, cause the power conversion device to perform operations comprising:

• receiving one or more signals from a master power conversion device;
• determining a master command phase from the one or more signals, wherein the master command phase indicates a phase of a master voltage command in a master rotating coordinating system of the master power conversion device;
• generating a voltage command having a command phase in a rotating coordinate system of the power conversion device based on a torque target value, wherein a rotating magnetic field for driving a rotor of an induction motor is generated to rotate with the rotating coordinate system;
• calculating a rotation phase of the rotating coordinate system based on a command phase difference between the master command phase and the command phase to reduce the command phase difference;
• and
• controlling a power conversion circuitry to output a driving power to the induction motor, based on the rotation phase and the voltage command, so that the rotating magnetic field is in synchronization with a master rotating magnetic field generated by the master power conversion device.