Control system for three-phase rotary machine

A system for controlling a three-phase inverter, having high- and low-side switching elements for each phase thereof, for supplying, based on direct-current (DC) power from a DC power source, alternating-current (AC) power to a three-phase rotary machine for rotating the three-phase rotary machine, the system comprising:

• a two-phase modulation module configured to perform two-phase modulation on three-phase command signals for controlling the three-phase inverter, each having a predetermined amplitude, to generate two-phase modulated command signals for the three-phases of the three-phase inverter,
• the two-phase modulated command signals being configured such that one of the two-phase modulated command signals is successively selected to be fixed to one of an upper limit and a lower limit of a corresponding one of the three-phase command signals for each predetermined period,
• two of the two-phase modulated command voltage signals except for one of the two-phase modulated command signals fixed to one of the upper limit and the lower limit being referred to as first and second two-phase modulated command signals;
• and
• an on-off performing module configured to:
• compare in magnitude a triangular carrier wave, having a predetermined amplitude based on the amplitude of each of the three-phase command signals, with the first and second two-phase modulated command signals;
• and
• perform, based on a result of the comparison, on-off operations of the high- and low-side switching elements of two phases of the three-phase inverter corresponding to the first and second two-phase modulated command signals while fixing, to be on or off, the high- and low-side switching elements of a remaining phase of the three-phase inverter;
• and
• a current measuring module configured to measure a value of a current flowing through one of first and second buses connected between the DC power source and the three-phase inverter when a local peak of the triangular carrier signal occurs while none of the high-side switching elements of all the three-phases are on or none of the low-side switching elements of all the three-phases are on.