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US 2002/0171389 A1Published application
Motor control device
AssigneeKabushiki Kaisha Toshiba
InventorYosuke Nakazawa
Life of this patent
Estimating the term…
Abstract
A pulse synchronized with the period of PWM of inverter and depending on the inferred value of the position of the motor rotor is applied as a PWM pattern to the motor and as a result the difference of magnetic resistance of the motor rotor, which can be inferred by observing the rate of change with time of the d axis current and q axis current on the d and q axis co-ordinates of the current flowing through the motor winding is detected and the position of the motor rotor can be thereby inferred. Thus the position of the motor rotor can be ascertained with high precision by a straightforward device construction without employing a rotor position sensor and reduction in size, reduction in costs and facilitation of maintenance can be achieved.
Claims8
A motor control device including
- a motor rotor having magnetically protruding polarity;
- an inverter that converts DC power to AC power;
- and
- a control unit that supplies an output from said inverter to said motor rotor, comprising:
- a PWM pattern generating unit that calculates and outputs a PWM pattern such as to output a pulse synchronized with a period of pulse width modulation (PWM) of said inverter and depending on an inferred position value of said motor rotor;
- a current co-ordinate conversion unit that, using said inferred position value of said motor rotor converts a three-phase current to actual values of a d axis current and q axis current, which are values on a d and q co-ordinate axes (q axis:
- direction of a protruding polarity of said motor rotor, d axis:
- direction at right angles to a direction of protruding polarity of said motor rotor);
- a d and q axis rate of current change calculating unit that respectively calculates and outputs rates of change with time of said d axis current and q axis current actual values, which are outputs from said current co-ordinate conversion unit, synchronized with a PWM pattern which is an output from said PWM pattern generating unit;
- and
- a motor rotor position inferring unit that infers and calculates a position of said motor rotor, using said PWM pattern which is output from said PWM pattern generating unit and said d axis rate of current change and q axis rate of current change which are output from said d and q axis rate of current change calculating unit and outputs a calculated value as an inferred position value of said motor rotor.
8 more elements
A motor control device including
- a motor rotor having magnetically protruding polarity;
- an inverter that converts DC power to AC power;
- and
- a control unit that supplies an output from said inverter to said motor rotor, comprising:
- a current control unit that manipulates a d axis voltage instruction and q axis voltage instruction of said inverter output such that an actual values of said d axis current and q axis current (q axis;
- direction of a protruding polarity of said motor rotor, d axis:
- direction at right angles to a direction of protruding polarity of said motor rotor) of said motor track a current instruction value;
- a PWM pattern generating unit that calculates and outputs a PWM pattern such as to superimpose on said d axis voltage instruction and q axis voltage instruction a d axis positive/negative pulse of a same period as a period of pulse width modulation (PWM) of said inverter in an inferred d axis direction found from an inferred position value of said motor rotor, using said inferred position value of said motor rotor and the d axis voltage instruction and q axis voltage instruction which are output from said current control unit;
- a current co-ordinate conversion unit that, using said inferred position value of said motor rotor converts a three-phase current of said motor to actual values of said d axis current and q axis current, which are values on d and q co-ordinate axes;
- a d and g axis rate of current change calculating unit that respectively calculate and output rates of change with time of d axis current and q axis current actual values, which are outputs from said current co-ordinate conversion unit, synchronized with a PWM pattern which is an output from said PWM pattern generating unit;
- and
- a motor rotor position inferring unit that infers and calculates a position of said motor rotor, using a PWM pattern which is output from said PWM pattern generating unit and d axis rate of current change and q axis rate of current change which are output from said d and q axis rate of current change calculating unit and outputs a calculated value as an inferred position value of said motor rotor.
9 more elements
Dependencies are inferred from the claim text.