Eaton Intelligent Power Limited

Gabriel Teixeira Braga

Stan Rex Simms

Irving Albert Gibbs

Thomas Arthur Farr

Geraldo Nojima

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

Inventive concepts herein relate to mitigating phase current oscillations and vibrations in a spinning, lightly loaded three-phase electric motor. A motor starter can transition between various acceleration profiles defined by unique firing angles and/or firing angle rates of change. These transitions adjust the firing angle of thyristors, which directly manage each phase of a three-phase power supply to the motor. The motor start can identify when a motor has residual motion from prior operation and can modulate the firing angle and/or firing angle rate of change accordingly to reduce a duration of time that issues such as phase current oscillations or vibrations might occur.

Control systems and methods for mitigating motor start-up instabilities in lightly loaded conditions near synchronous speed

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

An apparatus includes an inverter configured to be connected to a load, a driver having an output coupled to control terminals of transistors of the inverter and a control input configured to receive control vectors and responsively apply control signals to control terminals of the inverter, a desaturation detector configured to detect desaturation of the transistors, and a controller coupled to the control input of the driver and configured to apply at least one test vector that causes the driver to turn on selected ones of the transistors for a duration sufficient for the desaturation detector to detect desaturation of at least one of the selected transistors and to enable or inhibit further operation of the inverter responsive to the desaturation detector. The load may be a motor and the controller may be configured to apply the at least one test vector responsive to a command to start the motor.

Growing community of inventors

Belo Horizonte, Brazil

Gabriel Teixeira Braga