Control device for electric rotating machine and method of controlling the machine

A control device which controls a controlled variable of an electric rotating machine by controlling a power inverter circuit applying a controlled voltage to the electric rotating machine, comprising:

• a pattern preparing unit that prepares a pattern having a level changed with time for each of values of a modulation factor;
• a determining unit that determines phase information of the controlled voltage and an instructed value of the modulation factor;
• a selecting unit that selects the pattern, corresponding to the instructed value of the modulation factor, from the patterns of the pattern preparing unit;
• and
• a pattern control unit that controls the controlled variable of the electric rotating machine by controlling the power inverter circuit such that the controlled voltage of the power inverter circuit is changed with time according to the selected pattern while adjusting a phase of the control led voltage according to the phase information,
• wherein the pattern preparing unit prepares a triangular wave having a cycle duration, which is equal to a value obtained by dividing an electrical angle cycle duration of the electric rotating machine by an integral number, and prepares each pattern as a triangular wave quasi-comparison pattern so as to have both a first period of a first level, depending on the corresponding value of the modulation factor and including a timing synchronized with a crest point or a trough point of the triangular wave, and a second period of a second level, depending on the corresponding value of the modulation factor and including a timing synchronized with the other point of the triangular wave, and
• wherein the pattern control unit controls the power inverter circuit to apply a low level of the controlled voltage to the electric rotating machine in response to the first period of the selected triangular wave quasi-comparison pattern and to apply a high level of the controlled voltage to the electric rotating machine in response to the second period of the selected triangular wave quasi-comparison pattern.