Schneider Electric Usa, Inc.

Other

Square D Company

Zhi Gao

Roy Stephen Colby

Larry A Turner

Thomas G Habetler

Ronald Gordon Harley

Benoit Leprettre

Ronald G Harley

A method and apparatus to dynamically and adaptively demodulate induction motor instantaneous rotor slot harmonic frequency for line-connected squirrel-cage polyphase induction motors. The instantaneous rotor slot harmonic frequency carries essential information on the instantaneous rotor speed. Based on a correlation between the motor's input power and its rotor slot harmonic frequency, a dynamically varying carrier frequency is computed and used in a rotor slot harmonic frequency detector. The rotor slot harmonic frequency detector is based on a superheterodyne principle. It contains a generalized linear-phase low-pass filter, whose bandwidth is estimated dynamically by a filter bandwidth estimator. The rotor slot harmonic frequency detector also includes a latency compensator, which receives the dynamically varying carrier frequency signal and synchronizes it with the output of a frequency demodulator.

Systems, methods, and devices for demodulating induction motor instantaneous rotor slot harmonic frequency

A Complex Adaptive Phase Discriminator (PD), as presented in some concepts of the present disclosure, is an adaptive filter that accurately estimates the instantaneous frequency of a dynamic complex signal. The PD can demonstrate accurate instantaneous frequency estimation and rapid convergence in dynamic complex signal environments, even when the frequency of its input may change rapidly. A direct PD architecture can estimate the instantaneous frequency of a complex primary signal, iteratively adapting a phase of a complex exponential by minimizing the mean squared error of a complex error signal. Instantaneous frequency can be directly estimated from the phase of the complex exponential. In contrast, an indirect PD architecture can estimate the instantaneous frequency of a complex primary signal, iteratively adapting a complex coefficient by minimizing the mean squared error of a complex error signal. Instantaneous frequency can be indirectly estimated by extracting the phase of the complex coefficient.

Complex adaptive phase discriminator

Methods and devices are presented herein for estimating induction motor inductance parameters based on instantaneous reactive power. The induction motor inductance parameters, e.g., the stator inductance and the total leakage factor, can be estimated from motor nameplate data and instantaneous reactive power without involving speed sensors or electronic injection circuits. In one embodiment, the method includes: measuring voltages and currents; converting the measured voltages and currents into discrete-time voltage and current samples by analog-to-digital converters; synthesizing a complex voltage from the discrete-time voltage samples; synthesizing a complex current from the discrete-time current samples; acquiring and storing motor nameplate data; detecting instantaneous rotor speed by calculating an instantaneous rotor slot harmonic frequency with respect to an instantaneous fundamental frequency; calculating, via an induction motor inductance estimator, the motor's instantaneous reactive power and other intermediate quantities; and outputting the stator inductance and the total leakage factor.

Methods and devices for estimation of induction motor inductance parameters

Methods of determining a quantity of rotor slots in an induction motor are disclosed. An approximate slip is calculated according to an approximate slip function. A fundamental frequency is calculated from a representation of the voltage signal. A saliency frequency is calculated from a representation of the current signal. For each rotor slots index in a set of rotor slots indices, a slip estimate is calculated according to a slip estimation function. A slip estimation error signal is calculated. A rotor slots performance surface representative of an aggregate of the slip estimation error signals is calculated. A rotor slots quantity equal to the rotor slots index corresponding to a minimum of the rotor slots performance surface over at least a portion of the set of the rotor slots indices is defined.

Methods and apparatus for estimating rotor slots

A method of determining a quantity of rotor slots in an induction motor through analysis of voltage and current signals. An approximate slip is calculated according to an approximate slip function that is independent of a rotor slots quantity. A fundamental frequency is calculated from a representation of the voltage signal. A saliency frequency is calculated from a representation of the current signal. For each rotor slots index in a set of rotor slots indices, a slip estimate is calculated according to a slip estimation function that includes the saliency frequency, a saliency order, the fundamental frequency, a rotor slots index in the set of rotor slots indices, and a quantity of poles of the motor, such that the slip estimate is evaluated at respective ones of the set rotor slots indices. A slip estimation error signal is calculated according to a slip estimation error function that includes a difference between the approximate slip and respective ones of the slip estimates. A rotor slots performance surface representative of an aggregate of the slip estimation error signals evaluated over the set of the rotor slots indices is calculated. A rotor slots quantity equal to the rotor slots index corresponding to a minimum of the rotor slots performance surface over at least a portion of the set of the rotor slots indices is defined.

A method and apparatus to provide estimates of electrical parameters for line-connected induction motors during either steady-state or dynamic motor operations. The electrical parameters are calculated from the motor nameplate data and voltage and current measurements. No speed sensors or electronic injection circuits are needed. The method can be divided into 4 major steps. First, complex space vectors are synthesized from voltage and current measurements. Second, the instantaneous rotor speed is detected by calculating the rotational speed of a single rotor slot harmonic component with respect to the rotational speed of the fundamental frequency component. Third, the positive sequence fundamental frequency components are extracted from complex space vectors. Finally, least-squares estimates of the electrical parameters are determined from a dynamic induction motor equivalent circuit model.

Method and apparatus for estimating induction motor electrical parameters

A method of determining a slip estimate associated with an induction motor through analysis of voltage and current signals. A fundamental frequency is calculated from a representation (e.g., complex representation) of the voltage signal, and a saliency frequency is calculated from a representation of the current signal. An estimation of slip quantity is calculated according to a slip estimation function that includes the saliency frequency, a saliency order, the fundamental frequency, a quantity of rotor slots, and a quantity of poles of the motor.

Methods and apparatuses for estimating transient slip

A method and apparatus to provide continuous and reliable rotor temperature estimates for line-connected induction motors during steady-state and/or dynamic motor operations. Rotor temperature is calculated from voltage and current measurements without any temperature or speed sensors. First, complex space vectors are synthesized from voltage and current measurements. Second, the instantaneous rotor speed is detected by calculating the rotational speed of a single rotor slot harmonic component with respect to the rotational speed of the fundamental frequency component. Third, the positive sequence fundamental frequency components are extracted from complex space vectors. Fourth, the rotor time constant is estimated in a model-reference adaptive system based on a dynamic induction motor equivalent circuit model. Finally, the rotor temperature is calculated according to the linear relationship between the rotor temperature and the estimated rotor time constant. Real-time induction motor thermal protection is achieved through this continuous tracking of the rotor temperature.

Method and apparatus for estimating induction motor rotor temperature

An induction motor having a rotor and a stator is protected during running overloads by connecting the motor to an overload protection relay that can be tripped to interrupt power to the motor in the event of an overload, tracking the stator winding temperature of the motor during running overloads with a hybrid thermal model by online adjustment in the hybrid thermal model, and tripping the overload protection relay in response to a predetermined running overload condition represented by the tracked stator winding temperature. In one embodiment of the invention, the stator winding temperature is tracked by use of an online hybrid thermal model that uses the resistance of the rotor as an indicator of rotor temperature and thus of the thermal operating conditions of the motor. The hybrid thermal model incorporates rotor losses and heat transfer between the rotor and the stator, and approximates the thermal characteristics of the rotor and stator.

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Raleigh, NC, United States of America

Zhi Gao