System and method for starting and operating a motor
First Claim
1. A method for determining an initial position of a rotor of a polyphase motor comprising:
- determining current change values from a plurality of phases of the motor during saturation of the motor relating to the initial position of the rotor;
identifying a set of modelled current change values according to a modelled behaviour of the motor, the modelled current change values representing modelled positions of the rotor under the modelled behaviour;
transforming the current change values into a lower dimensional space;
transforming the set of modelled current values into the lower dimensional space; and
comparing the current change values in said lower dimensional space to the set of modelled current change values in said lower dimensional space to identify the initial rotor position from the modelled positions,wherein each current change value of said current change values is obtained by;
providing a first voltage pulse having a magnitude and duration to a pair of phases of the plurality of phases in a first direction; and
observing a first resulting current appearing on the pair of phases;
providing a second voltage pulse having said magnitude and said duration of said first voltage pulse to the pair of phases in a second direction opposed to the first direction; and
observing a second resulting current appearing on the pair of phases; and
obtaining the each current change value as the difference between the first resulting current and the second resulting current.
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Accused Products
Abstract
A method for determining an initial position of a rotor of a polyphase motor is described. The method comprises determining current change values from a plurality of phases of the motor during saturation of the motor relating to the initial position of the rotor; identifying a set of modelled current change values according to a modelled behaviour of the motor, in which the modelled current change values represents modelled positions of the rotor under the modelled behaviour; and comparing the current change values to the set of modelled current change values to identify the initial rotor position from the modelled positions. A system implementing the method is also described.
88 Citations
18 Claims
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1. A method for determining an initial position of a rotor of a polyphase motor comprising:
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determining current change values from a plurality of phases of the motor during saturation of the motor relating to the initial position of the rotor; identifying a set of modelled current change values according to a modelled behaviour of the motor, the modelled current change values representing modelled positions of the rotor under the modelled behaviour; transforming the current change values into a lower dimensional space; transforming the set of modelled current values into the lower dimensional space; and comparing the current change values in said lower dimensional space to the set of modelled current change values in said lower dimensional space to identify the initial rotor position from the modelled positions, wherein each current change value of said current change values is obtained by; providing a first voltage pulse having a magnitude and duration to a pair of phases of the plurality of phases in a first direction; and
observing a first resulting current appearing on the pair of phases;providing a second voltage pulse having said magnitude and said duration of said first voltage pulse to the pair of phases in a second direction opposed to the first direction; and observing a second resulting current appearing on the pair of phases; and obtaining the each current change value as the difference between the first resulting current and the second resulting current. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system for determining an initial position of a rotor of a polyphase motors, comprising:
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sense circuitry for determining current change values from a plurality of phases of the motor during saturation of the motor relating to the initial position of the rotor; and a motor controller that accesses a set of modelled current change values according to a modelled behaviour of the motor, the modelled current change values representing modelled positions of the rotor under the modelled behaviour; transforms the set of modelled current values into a lower dimensional space; receives the current change values from the sense circuitry and transforms the current change values into the lower dimensional space; compares the current change values in the lower dimensional space to the set of modelled current change values in the lower dimensional space to identify the initial rotor position from the modelled positions; provides a first voltage pulse having a magnitude and duration to a pair of phases of the plurality of phases in a first direction; obtains from the sense circuitry a first resulting current appearing on the pair of phases; provides a second voltage pulse having said magnitude and duration of said first voltage pulse to the pair of phases in a second direction opposed to the first direction; obtains from the sense circuitry a second resulting current appearing on the pair of phases; and obtains each current change value of the current change values as the difference between the first resulting current and the second resulting current. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A motor controller used in system that determines an initial position of a rotor of a polyphase motor, the motor controller comprising instructions operating on a microprocessor:
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to access a set of modelled current values according to a modelled behaviour of the motor, the modelled current change values representing modelled positions of the rotor under the modelled behaviour; to transform the set of modelled current values into a lower dimensional space; to receive current change values from sense circuitry in the system and transforms the current change values into the lower dimensional space and to compare the current change values in the lower dimensional space to the set of modelled current change values in the lower dimensional space to identify the initial rotor position from the modelled positions; to provide a first voltage pulse having a magnitude and duration to a pair of phases of the plurality of phases in a first direction; to obtain from the sense circuitry a first resulting current appearing on the pair of phases;
to provide a second voltage pulse having said magnitude and duration of said first voltagepulse to the pair of phases in a second direction opposed to the first direction; to obtain from the sense circuitry a second resulting current appearing on the pair of phases; and to obtain each current change value of the current change values as the difference between the first resulting current and the second resulting current, wherein the sense circuitry determines said current change values from a plurality of phases of the motor during saturation of the motor relating to the initial position of the rotor. - View Dependent Claims (15, 16, 17, 18)
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Specification