Motor drive system and its control method
AssigneeToyota Jidosha Kabushiki Kaisha
InventorKenji Yamada
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Abstract
A ripple detection unit detects a ripple current width of a motor current controlled according to PWM control. A ripple reference setting unit sets a reference value of the ripple current width. A frequency adjusting unit sets a control signal indicating a carrier frequency of the PWM control according to a ripple current width deviation. A carrier generation unit generates a carrier of the frequency based on the control signal. Thus, it is possible to realize feedback control of the carrier frequency for maintaining the ripple current width at an appropriate level.
Claims15
A motor drive system, comprising
- an AC electric motor having a rotor with a permanent magnet attached thereon;
- a power converter for controlling power supply to said AC electric motor by on/off control of a plurality of power semiconductor switching elements under pulse width modulation control;
- a current detector for detecting a motor current flowing between said power converter and said AC electric motor;
- a ripple detecting unit for detecting a ripple current width of said motor current, corresponding to switching frequency of each of said power semiconductor switching elements, based on a detected value from said current detector;
- a reference setting unit for setting a reference value of said ripple current width;
- and
- a frequency adjusting unit for controlling frequency of a carrier used for said pulse width modulation control, based on a comparison between said ripple current width detected by said ripple detecting unit and said reference value set by said reference setting unit.
A motor drive system control method, for controlling a motor drive system including an AC electric motor having a rotor with a permanent magnet attached thereon, a power converter controlling power supply to said AC electric motor by on/off control of a plurality of power semiconductor switching elements under pulse width modulation control, and a current detector detecting a motor current flowing between said power converter and said AC electric motor, comprising the steps of:
- detecting a ripple current width of said motor current, corresponding to switching frequency of said power semiconductor switching elements, based on a detected value from said current detector;
- and
- controlling frequency of carrier used for said pulse width modulation control, based on a comparison between the detected ripple current width and a reference value of said ripple current width.
Dependencies are inferred from the claim text.