Unico Corp.

William S Hammel

Mark E Garlow

Keith W Van Patten

Ramdas M Pai

Harry W Schulz

Michael O Lucas

Rick L Tennessen

James J Sewell

Donald B Lawson

David R Seidl

There is disclosed an apparatus and method to reduce total harmonic distortion input into a 24-pulse autotransformer system and the autotransformer system itself. The 24-pulse autotransformer system is configured to receive an input of a first voltage and produce an output voltage of a second voltage. The system includes a pair of autotransformers coupled to an AC power source. One winding of each phase of the first autotransformer has a turn ratio to effect a decrease in the voltage across said winding over a symmetric voltage value and a second winding of each phase of the first autotransformer has a turn ratio to effect a decrease in the voltage across said winding over a symmetric voltage value, thereby reducing total harmonic distortion (THD) in the input current to the system without a zero sequence blocking transformer.

Autotransformer system reducing total harmonic distortion

An apparatus is provided for controlling operation of an electric motor through use of an additional power storage arrangement connected across the DC busses of a motor drive and controlling the speed of the motor. The additional power storage arrangement includes an additional capacitor arrangement and a rate limiting arrangement in a series circuit relationship with one another.

Apparatus for continued operation of an electric motor during an interruption in input power

Presented is a harmonic regulator that regulates a plurality of individual harmonics in a system having periodic torque disturbances to commanded values, including zero. For each harmonic being regulated, a feedback signal having at least one harmonic component due to the harmonic being regulated is transformed from a source reference frame to a harmonic reference frame of the harmonic being regulated to form a qd feedback signal. The qd feedback signal is subtracted from the commanded value to form a qd signal and regulated. The regulated qd signal is transformed to a destination reference frame to form a compensation signal and the compensation signal is added to a control signal to form a qd control signal that drives each harmonic being regulated towards the commanded value.

Bus disturbance regulator

Harmonic disturbance regulator

A digital current regulator for controlling the operation of an inductance device such as an AC motor. A plurality of independently controllable insulated gate bipolar transistors are selectively enabled to vary the instantaneous phase and magnitude of current applied to an AC motor. To minimize induced back EMFs during current switching operations, a number of safeguards are utilized. Switching between adjacent states only is provided to minimize the magnitude of instantaneous current changes. A 'ready blocking' function limits the maximum switching frequency to avoid significantly derating the switching device capabilities, while a 'time out' feature assures system operation above at least a minimum switching frequency to further minimize the magnitude of instantaneous current changes. A time hysteresis function is provided to avoid switching device response to false feedback control signals.

Digital current regulator

A linear resolver utilizes multiple pairs of nulled coil sets arranged co-linearly for sensing the position of multiple edges of a magnetically permeable object. An excitation coil produces an alternating magnetic field which is normally weakly coupled to the nulled coil sets across a magnetic gap. As the object covers the area of the gap, the coupling between the excitation and the individual coils in a nulled coil set is increased. Each nulled coil set produces an output which varies cyclically with increasing coverage of the object. The two nulled coil sets in each pair of nulled coil sets are offset from each other so that their cyclical outputs are offset by one quarter cycle, or 90.degree. with respect to the area of coverage by the object. Detection means are provided which resolve the outputs from a pair of nulled coil sets to precisely determine the position of the object edge. Each nulled coil pair is processed separately by the detection means so that multiple edges can be detected.

Growing community of inventors

Franksville, WI, United States of America

William S Hammel