Motor Control

This method of the IM (Induction Machine) control was not in wide use before solid state converters were available. This expert's problem was to design such a converter to control the motor that was remote from the source, for around 200.0 m (660.0 feet). Vector control theory was just born, but fast calculating cheap computers (microprocessors) were not yet available.

This is why fast reaction was the chosen way to measure Power Factor, phase shift between Voltage and Current on the converter's output. Now those methods are developed in P-Q (** see below) control and maybe some of this expert's efforts are in its foundation. It was extremely difficult to extract and transform information in the Voltage form for use in the control system. To resolve this problem, an invention was created, based on a simple method of charging the capacitor by the constant current, in a time frame between Voltage and Current “0”s.

The second challenge was to keep the motor stable under disturbances; where the ability to install (remote and submerged) reliable sensors was practically impossible. The created invention solved this problem by using positive feed forward from the converter's DC input and negative feed back from the converter's output. Mathematically, it was proven that with certain combinations of the gains, signal on the comparator's output is proportional to the converter's load (disturbances). Thus, the method of indirect disturbances measurement was created; which is very productive, especially in DC/DC converters control theory and practices.

**P-Q control- control theory and practice based on instantaneous measurement of the real and reactive power, calculations of the power factors and system's stabilization based on balancing source-load power

To see the resume of the expert associated with this case study, see the link below.