Abstract: A protection scheme to protect pulse width modulated drives is described. The scheme is implantable in both hardware and software and combinations thereof. The semiconductor devices of the drive are protected from transient signals such as power line spikes and loss of line. The present scheme uses an adaptive technique to determine the normal or steady state distortion (transients and harmonics) value in an unfiltered power signal. The present distortion value is compared to the normal distortion. If the present distortion exceeds the steady state value by a given amount, then the drive is placed in freewheel mode to protect the semiconductor devices in the drive.

Abstract: A method and apparatus that includes determining differences between a process model and an actual process are used as a diagnostic system for the actual process. The process model includes elements from a design process to provide a “known good” condition for evaluating the differences. Initial input states to the process model are the initial input states to the actual process. Output information correlated to states in the actual process is provided by controls, such as programmable logic controllers, that manage the actual process.

Abstract: An apparatus includes a sense element and an oscillator. The oscillator is coupled to the sense element and is used to generate an oscillator signal and a gain control signal. The oscillator signal is amplitude compensated when noise is detected in the sense element. A method includes detecting magnetic interference in a sense element coupled to an oscillator, and adjusting a gain control signal in the oscillator to compensate for the magnetic interference.