Caterpillar Inc.

Joshua M Williams

Mark E Hartman

Jackson Wai

Alexander Cameron Crosman, Iii

Brett Michael Nee

Benjamin Paul Gottemoller

Jesse R Gerdes

Robert Wayne Lindsey

Ahmed Khalil

Gregory J Speckhart

James David Siegle

Srikar Thaduvayi

A traction motor system calculates motor flux by generating a real time effective resistance of a resistance grid calculated from motor torque and measured voltage on a DC link. Calculating effective resistance avoids solely relying on DC link voltage, which can be influenced by conditions such as wheel slip and drop out of one or more resistance grids. The effective resistance calculation is based on nominal motor values using known power levels and conditions. From these nominal values and the effective resistance, various scaling factors based on actual motor power can be generated and used to adjust a nominal flux reference to more accurately reflect actual motor flux. The scaling factors include power and torque scaling factors and a resistance scaling factor that is active during conditions such as wheel slip.

Traction motor retarding flux reference

The disclosure describes, in one aspect, a system for a machine having an electric drive configuration. The system includes an electric motor associated with at least one wheel and adapted to provide retarding torque to the wheel, and a controller configured to determine a power measurement of a retarding grid and control the retarding torque to the at least one wheel during retarding as a function of the power measurement.

Controlling retarding torque in an electric drive system

A control system () for controlling a switched reluctance (SR) machine () having a rotor () and a stator () is provided. The control system () may include a converter circuit () operatively coupled to the stator () and including a plurality of switches () in selective communication with each phase of the stator () and a controller () in communication with each of the stator () and the converter circuit (). The controller () may be configured to determine a position of the rotor () relative to the stator (), and generate a modulated switching frequency () based on the rotor position.

Switching frequency modulation utilizing rotor position

A method of controlling a motor is provided. The method may determine a speed of the motor, and engage a soft chopping routine on a first switch and a second switch of each phase if the motor speed is relatively low. The first switch may be driven by a first pulse width modulated PWM signal and the second switch being driven by a second PWM signal. The first and second PWM signals may be alternatingly configured such that at least one of the first switch and the second switch is closed at any point during the distributed soft chopping routine and both the first switch and the second switch are never simultaneously open.

Switching strategy for switched reluctance machine

A method of testing power converter current sensors is disclosed. The method may include receiving a current sensor test request and receiving measured currents from current measurements from the at least one current sensor, based on the test request. The method may further include comparing the measured current of the sensor with a stored profile and determining whether a fault exists in each current sensor being tested. The method may also include providing a user with a test report.

Power converter current sensor testing method

A method of voltage supply management for an electric drive system includes receiving a voltage signal () indicative of a voltage in a supply link, and one or more condition signals that are indicative of an operating condition of the electric drive system. A difference between a desired voltage value (), which is calculated based on the voltage signal () and the one or more condition signals, and the voltage signal () yields a voltage error signal (). The voltage error signal () is evaluated to indicate an over-voltage condition or an under-voltage condition. Power is dissipated from the supply link when an over-voltage condition is present and a torque command limit with respect to the one or more electric drive motors () is imposed when an under-voltage condition is present.

Over-voltage and under-voltage management for electric drive system

A system is provided for controlling an electric machine. The system has a power source configured to supply electric energy to the electric machine. In addition, the system has an inverter operationally connected to the power source and the electric machine and configured to increase or decrease a rotor flux component of a voltage applied to the electric machine, while maintaining a torque component at an essentially constant level. The system further has a control device configured to determine at least one parameter of the electric machine and operate the inverter in either a first or a second mode in response to the at least one determined parameter.

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Peoria, IL, United States of America

Joshua M Williams