Eaton Intelligent Power Limited

Eaton Corporation

Thomas Arthur Farr

Irving Albert Gibbs

Stan Rex Simms

Gabriel Teixeira Braga

Ron Carl Schueneman

Hanning Tang

John David Maurin, Jr

Alfred Lee Randall

John Austin Cochran

Geraldo Nojima

Steven Dale Walker

Benjamin Stewart Wells

Paul M Mulligan

Harry Broussard

Richard Bhalla

Tap Van Pham

Rafael Gutierrez

Gregory John Venhaus

Aaron H VanderMeulen

Donovan Gray

Richard B Ravenell

Marcus Eugene Case

John David Maurin

Aaron H Vandermeulen

Methods of testing a multilevel inverter include selectively pulsing (i.e., attempting to turn on) at least one of the inner and outer switches of the inverter and determining a status of at least one of the inner switches, the outer switches and the neutral clamping diodes of the inverter based whether the pulsed at least one of the inner and outer switches desaturates. The pulsing may be preceded by charging the DC bus to a predetermined voltage magnitude that is less than a nominal working voltage magnitude of the DC bus, e.g., the predetermined voltage magnitude may be around 50% or less of the nominal working voltage magnitude.

Inverter diagnostic testing methods and apparatus

An apparatus includes a plurality of DC buses and a plurality of inverter circuits, respective ones of which are coupled to respective ones of the plurality of DC buses. The apparatus further includes a control circuit configured to generate a representative DC voltage signal based on DC voltage signals for respective ones of the DC buses, to generate a first modulation control signal from the representative DC voltage signal, to generate second modulation control signals for the respective inverter circuits from the representative DC voltage signal and the first modulation control signal that are normalized based on the DC voltage signals for the buses and the representative DC voltage signal, and to modulate the inverter circuits responsive to respective ones of the second modulation control signals. The representative DC voltage signal may represent a maximum of the DC voltages for the respective DC buses.

Adjustable frequency drives using normalized modulation control signals to compensate for phase imbalance and methods of operating the same

A reduced voltage starter for electric motors comprises a controller, and a plurality of semiconductor switches to selectively connect a power source to a motor. The controller is configured to apply a first voltage ramp to provide a controllable fraction of the full line voltage to the motor, while maintaining a current flow to be within a programmable current limit during motor startup. The controller is further configured to implement a bumpless force transition, by applying a second voltage ramp when the speed of the motor is below the rated motor speed, and force transition criteria correlated with overheating of the semiconductor switches and/or a connected load are met.

Apparatus and methods for reduced voltage starting of motors with bumpless force transition

A converter of a variable frequency drive (VFD) is operated in a ramp-up mode to produce an AC output voltage for accelerating a motor. A loading of the converter is determined concurrent with the ramp-up mode. Transfer of the motor to a bypassed mode is conditioned on whether the determined loading in the ramp-up mode meets a criterion. In some embodiments, conditioning transfer to the bypassed mode comprises foregoing transition to the bypassed mode based on a comparison of the determined loading to an underloading threshold.

Methods of protecting motors driven by variable frequency drives and variable frequency drive systems employing the same

An apparatus includes a magnetometer-based current sensor (e.g., a Hall-effect or fluxgate-based current sensor) configured to sense a magnetic field generated by a current in at least one conductor connecting a motor drive output to a motor and to responsively produce a first current sense signal and a magnetometer-based voltage sensor (e.g., a Hall-effect or fluxgate-based voltage sensor) configured to sense a magnetic field generated in response to a voltage of the at least one conductor and to responsively produce a first voltage sense signal. The apparatus further includes a signal conversion circuit configured to receive the first current sense signal and the first voltage sense signal and to generate a second current sense input and a second voltage sense input for provision to a current sense input and a voltage sense input, respectively, of a motor protection relay that protects the motor.

Motor protection relay interface using magnetometer-based sensors

An apparatus, such as an adjustable frequency drive (AFD), includes an inverter configured to be selectively coupled to a motor in a first mode and an AC line in a second mode and a control circuit configured to operate the inverter as a motor drive in the first mode and as a power compensator in the second mode. The power compensator may provide power factor correction. The control circuit may include a scalar controller configured to control the inverter according to a voltage vs. frequency characteristic determined by a field weakening point reference and the control circuit may vary the field weakening point reference in the second mode. The inverter may have an input coupled to a DC bus and the control circuit may be configured to adjust a frequency of the inverter in the second mode to increase a voltage on the DC bus.

Adjustable frequency drive systems and methods of employing power compensation

A motor starter apparatus includes an enclosure, a bypass contactor configured to be installed in the enclosure and configured to selectively couple a power source to a motor, and a reduced voltage soft starter (RVSS) circuit assembly (e.g. a wheeled truck) configured to be installed in the enclosure, to be coupled to the power source and to apply a variable voltage to the motor. The bypass contactor is configured to preserve a connection of the bypass contactor to the power source and the motor when the RVSS circuit assembly is removed from the enclosure.

Motor starter apparatus using independently rackable reduced voltage soft starter assembly

A motor starter includes a plurality of semiconductor switches configured to couple respective phases of an AC power source to respective phases of a motor and a control circuit configured to configured to selectively operate the semiconductor switches to gradually increase a voltage applied to the motor, to determine root mean square (RMS) current values of a current of the motor as the voltage increases, and to cause the semiconductor switches to apply a full voltage or a more steeply ramping voltage to the motor responsive to the RMS current values meeting a criterion.

Reduced voltage soft starter apparatus and methods using current-controlled transitions

An apparatus, such as a variable frequency drive (VFD), includes a rectifier, a DC bus coupled to an output of the rectifier and at least one capacitor coupled to the DC bus. The apparatus further includes a normally-conducting switch coupled to the DC bus and configured to discharge the at least one capacitor in a conducting state and a control circuit configured to control the normally-conducting switch responsive to an input to the rectifier. The control circuit may be configured to control the normally-conducting switch responsive to a voltage at the input of the rectifier. The control circuit may include a regulator circuit having an input coupled to the input of the rectifier and a driver circuit coupled to an output of the regulator circuit and configured to drive a control terminal of the normally-conducting switch.

Converter apparatus using source-activated discharge circuits

An electrical system () includes a transformer () coupled to an AC source () that provides a main AC voltage, the transformer having a number of sets of primary windings () and secondary windings (), and a charging module () structured to generate a magnetizing AC voltage. The charging module is structured to selectively provide the magnetizing AC voltage to: (i) one of the number of sets primary windings, or (ii) one of the number of sets secondary windings. The magnetizing AC voltage is such that responsive to the magnetizing AC voltage being provided to one of the sets of primary windings or one of the sets of secondary windings, one or more of the sets of primary windings will be magnetized in a manner wherein a flux of the one or more of the number of primary windings is in phase with the main AC voltage provided from the AC source.

System and method for magnetizing a transformer in an electrical system prior to energizing the electrical system

A protection system for an electrical apparatus is disclosed. The protection system includes a baffle assembly and a coating for electrical elements exposed to arc gases. The baffle assembly includes a number of generally planar sidewalls, each sidewall including a first edge surface, a second edge surface, and a third edge surface. The sidewalls are disposed in a spaced, generally parallel configuration defining a number of channels. A first end wall is sealingly coupled to each sidewall first edge. A second end wall is sealingly coupled to each sidewall second edge. A third end wall is sealingly coupled to each sidewall third edge. The terminals of an electrical apparatus are disposed in an aligned set with one set of terminals in each channel. The channels are structured to limit the flow of arc gases across adjacent sets of terminals.

Fuse arc gas baffle with arc resistant fuse assembly

A switchgear unit includes an enclosure having a first compartment and a second compartment and a fuse assembly mounted on a wall that separates the first compartment and the second compartment, the fuse assembly comprising a fuse housing disposed in the second compartment and accessible from the first compartment via an opening in the wall. The fuse assembly may include a cover configured to separate a fuse in the fuse housing from the first compartment and that is removable to provide access to the fuse from the first compartment. The fuse assembly may further include a power input terminal supported by the fuse housing and accessible from the second compartment and a switch disposed in the first compartment and configured to electrically connect the power input terminal to the first fuse connection terminal.

Switchgear unit with isolated input fuse holder assembly

An apparatus includes a magnetizing circuit configured to be coupled to a transformer and to selectively provide a magnetizing current to the transformer and a control circuit configured to cause the magnetizing circuit to provide the magnetizing current following disconnection of the primary winding of the transformer from the power source. The magnetizing circuit may be configured to provide the magnetizing current from a first source following disconnection of the primary winding from a second source. The transformer may include a first transformer and the apparatus may further include a second, higher impedance transformer coupled between the second source and the first transformer. In further embodiments, the magnetizing circuit may include a solid-state converter.

Methods and apparatus for soft operation of transformers using auxiliary winding excitation

A system includes a variable frequency drive (VFD) comprising an inverter having an output configured to be coupled to a motor and a switch configured to couple a power source to the motor to bypass the VFD. The system further includes a control circuit configured to synchronize the VFD to the power source, to operate the switch to couple the power source and the VFD in parallel and to subsequently disable the inverter responsive to a current of the inverter. In some embodiments, a PWM frequency of the VFD may be temporarily increased when transferring the motor from the power source to the VFD.

Closed-transition variable-frequency drive apparatus and methods

A protection system for an electrical apparatus is disclosed. The protection system includes a baffle assembly and a coating for electrical elements exposed to arc gasses. The baffle assembly includes a number of generally planar sidewalls, each sidewall including a first edge surface, a second edge surface, and a third edge surface. The sidewalls are disposed in a spaced, generally parallel configuration defining a number of channels. A first end wall, is sealingly coupled to each sidewall first edge. A second end wall is sealingly coupled to each sidewall second edge. A third end wall is sealingly coupled to each sidewall third edge. The terminals of an electrical apparatus are disposed in an aligned set with one set of terminals in each channel. The channels are structured to limit the flow of arc gasses across adjacent sets of terminals.

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Candler, NC, United States of America

Thomas Arthur Farr