Parker-hannifin Corporation

Christopher M Botka

Scott A Ellerthorpe

Jack Nordquist

Timothy J Damiano

Mark C Calahan

Mark J Calahan

Motor stall can be detected without the use of additional sensors in a hybrid stepper motor through the detection of a harmonic component an associated motor spectrum. The associate motor spectrum can be a motor command voltage spectrum. For example, all of the harmonic components except for the second harmonic are eliminated from the voltage and the presence or lack thereof indicates whether or not the motor has stalled. The harmonic component can be isolated with the use of several cascaded filters. These filters can include notch filters and bandpass filters. Additionally, the circuit may be realized as either an analog, digital or hybrid circuit. The motor may be either hybrid stepper motor having 2, 3, or 5 phases, or a variable reluctance motor.

Sensorless stall detection for motors

An energy absorbing filter for reducing mechanical oscillations in motor is disclosed. The energy absorbing filter places a virtual shunt across the motor windings so as to dissipate mechanical vibrations as resistive losses. This is accomplished by the placing of a large capacitance in parallel with the windings. The impedance of the filter and the windings combined is purely resistive. The motor may be any kind of motor including a 2-, 3-, or 5-phase hybrid step motor. The filter may be realized as an analog or digital filter, or may be a hybrid of the two. Additionally, the filter may be realized through hardware or through software in the form of a computer program.

Energy-absorbing filter for a motor

Passive electronic damping apparatus for a step motor of the type having a number of phase windings, comprising: a respective transconductance amplifier coupled to each phase winding for producing a phase drive current in the winding in response to a position command; each transconductance amplifier exhibiting an output impedance characteristic; and a circuit for changing the amplifier output impedance to effect motor damping.

Passive electronic damping for step motor

Apparatus for electronically producing a torque dependent signal for a plural drive phase synchronous step motor, without the use of an accelerometer or other external feedback device, includes a circuit for detecting respective instantaneous terminal voltage signals for at least two phases of the motor; another circuit for detecting respective instantaneous phase current signals for said at least two phases; and a signal processing circuit for combining the detected signals to produce said torque dependent signal.

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Santa Rosa, CA, United States of America

Christopher M Botka