Controller for synchronous machine

A method for controlling a synchronous machine, the method comprising the steps of:

• by a power converter, alternately converting direct current power and alternating current power;
• driving a synchronous machine by the power converter;
• by a PWM modulation section, performing PWM modulation for a voltage command value for controlling the synchronous machine;
• by a current detection section, detecting a current conducted to the synchronous machine at predetermined sampling timing;
• by a voltage detection section, detecting a voltage applied to the synchronous machine;
• by a first current variation operation section, operating a current variation during a time interval between timings synchronized with the detection sampling in the current detection section;
• by a first voltage integration operation section, operating a voltage integration value during a time interval between the same timings as the timings in the first current variation operation section;
• by a second current variation operation section, defining, as one set, the current variation of the first current variation operation section and the voltage integration value of the first voltage integration operation section during the time interval between the same timings, and operating a current variation during a time interval in which all operation timings of a plurality of the sets are included;
• by a second voltage integration operation section, operating a voltage integration value during the same time interval as the time interval of the second current variation operation section;
• and
• by a rotation phase angle assumption section, assuming a rotation phase angle of the synchronous machine by using the plurality of respective sets, the time intervals corresponding to the respective sets, the current variation and the voltage integration value during the time interval in which all the operation timings of the plural sets are included, and the time interval in which all the operation timings of the plural sets are included.