Variable-speed synchronous generator-motor device

A variable-speed synchronous generator-motor device comprising:

• a synchronous machine;
• a frequency converter including a semiconductor power converter and a current controller, the semiconductor power converter being connected to armature winding of the synchronous machine,
• the current controller being configured to:
• coordinate-convert an armature current of the synchronous machine into a direct-axis current and a quadrature-axis current based on a rotational phase reference;
• compare the direct-axis current with a direct-axis current command;
• compare the quadrature-axis current with a quadrature-axis current command;
• and
• control a synchronous machine side voltage of the frequency converter;
• and
• a variable speed mode regulator configured to compare a command value of active power or a rotational speed of the synchronous machine with a measurement value to output a result to the current controller as a first quadrature-axis current command value, wherein
• the variable-speed synchronous generator-motor device further comprises:
• a first switcher configured to switch an output between an update output and previous value holding of the first quadrature-axis current command value;
• a phase detector configured to measure a voltage phase of the synchronous machine;
• a phase calculator configured to calculate and output a target voltage phase of the synchronous machine based on a target frequency reference of the synchronous machine;
• a phase lead compensator configured to input a result of comparing the voltage phase with the target voltage phase as a phase shift;
• a synchronous machine mode regulator configured to output an output of the phase lead compensator as a second quadrature-axis current command;
• and
• a second switcher configured to switch an output between the second quadrature-axis current command and a zero output to bias the output to the first quadrature-axis current command value, and
• the first switcher switches from the update output to the previous value holding, and the second switcher simultaneously switches from the zero output to the second quadrature-axis current command.