Driving of a three-phase motor with fuzzy logic control of the slip
First Claim
1. A method of controlling pulse width modulation (PWM) driving of a multi-phase motor to limit slip to a maximum percentage of the stator drive frequency, wherein slip is a difference between a stator drive frequency and a rotor frequency corresponding to a rotational speed of the motor, the method comprising the steps of:
- inputting to a processor data representative of the rotor frequency, the stator drive frequency, a reference frequency corresponding to a required rotational motor speed, and a torque characteristic as a function of the stator drive frequency; and
determining an appropriate value of the stator drive frequency, a PWM modulation index and the maximum percentage value of the slip at a current rotor frequency by a fuzzy logic algorithm implemented in the processor and without using a look-up table of preestablished slip values.
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Accused Products
Abstract
Driving of a three-phase motor includes controlling the slip of the motor by way of a fuzzy logic algorithm. The simplicity and precision of the fuzzy control of the slip permits dynamically optimizing the efficiency of a three-phase motor under any operating condition, and thereby minimizing power consumption. The control is carried out by knowing: the effective speed of the motor that represents the feedback value, and that may be provided by a common encoder (typically a dynamo or an optic device) keyed on the motor'"'"'s spindled; the stator frequency imposed on the motor; the required speed; and, of course, the characteristic curve (frequency-torque) of the motor.
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Citations
27 Claims
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1. A method of controlling pulse width modulation (PWM) driving of a multi-phase motor to limit slip to a maximum percentage of the stator drive frequency, wherein slip is a difference between a stator drive frequency and a rotor frequency corresponding to a rotational speed of the motor, the method comprising the steps of:
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inputting to a processor data representative of the rotor frequency, the stator drive frequency, a reference frequency corresponding to a required rotational motor speed, and a torque characteristic as a function of the stator drive frequency; and determining an appropriate value of the stator drive frequency, a PWM modulation index and the maximum percentage value of the slip at a current rotor frequency by a fuzzy logic algorithm implemented in the processor and without using a look-up table of preestablished slip values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of controlling pulse width modulation (PWM) driving of a multi-phase motor to limit slip to a maximum percentage of the stator drive frequency, wherein slip is a difference between a stator drive frequency and a rotor frequency corresponding to a rotational speed of the motor, the method comprising the steps of:
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inputting to a processor data representative of the rotor frequency, the stator drive frequency, a reference frequency corresponding to a required rotational motor speed, and a torque characteristic as a function of the stator drive frequency; feeding to said processor data representative of electrical parameters of phase-windings of the motor; calculating by a fuzzy logic algorithm implemented in the processor a current rotor frequency corresponding to a current rotational speed of the motor as a function of the electrical parameters and of a power factor (cosφ
); anddetermining an appropriate value of the stator drive frequency, a PWM modulation index and the maximum percentage value of the slip at the current rotor frequency by a fuzzy logic algorithm implemented in the processor. - View Dependent Claims (10, 11, 12, 13)
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14. A driving system for a multi-phase motor of a type comprising a rotor and a stator, the driving system comprising:
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a generator circuit for generating pulse width modulation (PWM) drive signals at a certain base stator frequency as a function of digital control data for the stator frequency and for a PWM modulation index, respectively; a first digital comparator for comparing a first datum representative of a rotational speed of the motor and a second datum representative of a reference speed and for outputting a third error datum; a second digital comparator for comparing the first datum and the stator frequency and producing a fourth datum representative of slip; and a fuzzy logic processor for processing according to a fuzzy algorithm the third error datum, the fourth datum representative of slip, and the first datum representative of the rotational speed, and for producing a base frequency datum and a PWM modulation index datum. - View Dependent Claims (15, 16, 17, 18, 19)
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20. A driving system for controlling pulse width modulation (PWM) driving of a multi-phase motor to limit slip to a maximum percentage of the stator drive frequency, wherein slip is a difference between a stator drive frequency and a rotor frequency corresponding to a rotational speed of the motor, the driving system comprising:
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a processor; and input means for inputting to said processor data representative of the rotor frequency, the stator drive frequency, a reference frequency corresponding to a required rotational motor speed, and a torque characteristic as a function of the stator drive frequency; said processor comprising fuzzy logic means for determining an appropriate value of the stator drive frequency, a PWM modulation index and the maximum percentage value of the slip at a current rotor frequency by a fuzzy logic algorithm. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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Specification