Abb Inc.

Other

Abb Oy

Douglas W Karraker

Kalyan P Gokhale

Samuli J Heikkil&auml;

Alpo Vallinmaki

Dennis Tyczkowski

Donald J Truettner

Matti T Jussila

Ilkka T Pajari

Jeffrey A Brunner

A voltage measuring device includes an input configured to be coupled to a secondary of an inductive coupling of a DC to DC voltage converter. A switch coupled to the input forms a discharge path parallel to a sampling capacitor dependent on the voltage at the input equaling or exceeding a first voltage threshold and independent of an output voltage at the output of the device. The sampling capacitor is coupled to the output. A rectifier in series with the sampling capacitor is biased to conduct upon the input voltage, minus the output voltage, equaling or exceeding a second voltage.

DC bus voltage measurement circuit

A system for the detection of welded contacts in a circuit of a line converter system has a plurality of inverter switches, a plurality of utility switches in which a pair of utility switches is connected in series through a line to a utility, a voltage detector, an electronic controller, and a DC input source. The line converter system converts incoming DC power into AC output power that is delivered to the utility grid. The voltage detector measures the voltage across a first node and a second node of the circuit and provides an output that is interpreted by an electronic controller for each step performed during a method of detection of welded contacts. The detection method has a sequence of test steps in which at least one switch is opened and/or closed, a DC bus of the inverter or the utility grid is used as a stimulus voltage, and the voltage is measured. If a voltage is not detected across the first and second nodes, the test sequence is continued until a welded contact is detected or the electronic controller determines that none of the contacts are welded. If the controller determines that none of the contacts are welded, the line converter system is permitted to connect and supply AC power to the utility.

Detection of welded switch contacts in a line converter system

A motor bypass is controlled by a digital signal processor (DSP) with embedded control software that allows fault detection and annunciation, serial communications between both a variable frequency drive (VFD) and a bypass controller and the bypass controller and a host computer. The use of the DSP and embedded control software further allows for contactor coil control to provide fault tolerant operation as well as fault condition detection and annunciation to the user.

AC motor bypass with fault annunciation, serial communication and fault tolerant coil control

A system for use in ac to ac or dc to ac power conversion equipment to detect faults in an inverter when the inverter is in a high impedance mode. The system detects ground faults or cross wiring conditions by converting the inverter outputs to digital signals and evaluating the frequencies of the resulting signals. The system keeps the inverter in the high impedance mode until after it has been determined that neither of the described abnormal statuses exist. The system tests for both of the abnormal statuses on power up and thereafter tests only for a ground fault whenever the inverter switches are disabled.

Method and apparatus for detecting faults in AC to AC, or DC to AC power conversion equipments when the equipment is in a high impedance mode

The direct torque control (DTC) principle is used to control the torque of a wound ring rotor slip induction machine, also known as a doubly fed or cascade machine, by utilizing a solid state inverter on the rotor side. In addition, the DTC principle is used to control the power factor at the stator terminals of the doubly fed machine to a desired level and also to perform the task of synchronization of stator voltage to the grid voltage. An integrated controller is used to implement these three functions.

Controller for a wound rotor slip ring induction machine

An inverter control circuit includes means for continuously computing and subtracting an average voltage from each of three modulating input waveforms. The average voltage is computed by determining the instantaneous maximum and minimum voltages of the three waveforms, summing these voltages, and then dividing them by an averaging factor. The shifted modulating waveforms are then compared with a high-frequency carrier wave to modulate the duty cycles of the inverter outputs to approximate desired output waveform characteristics.

Growing community of inventors

Muskego, WI, United States of America

Douglas W Karraker