Seiberco Incorporated

Oriental Motor Boston Technology Group Incorporated

Other

Hung D Vu

Ralph W Horber

Yasuo Sato

Chikara Sugawara

Yoshinari Araki

Seiki Suzuki

Akihiko Hoda

Eiji Oi

A stepper motor system and apparatus use a position-feedback device, which may have a resolution capability as low as 200 counts per motor shaft revolution, for misstep detection and motor step recovery. In use of the system, position deviation is computed periodically and cyclically, by subtracting the feedback position from the corresponding commanded position, to determine the load angle, implicitly, and the operating status of the motor. If the load angle is within an established allowable range of values, normal stepper operation along the programmed trajectory is maintained, without adjustment. A load angle that exceeds the limits of that range however indicates that a misstep has occurred, and the system controller initiates immediate action to recover lost motor steps, to reestablish synchronism, and to then continue toward the final target position, with minimal loss of time.

Method and apparatus for misstep detection and recovery in a stepper motor

The heat-generating components of an integrated motor system are disposed proximate the motor body, for efficient heat dissipation, and the heat-sensitive components are segregated therefrom, physically and thermally.

Integrated electric motor and drive, optimized for high-temperature operation

An electronic circuit and software control methodology tracks motor position in a motor drive system. High power consumption position transducers, such as inductive sensors or optical encoders, can be controlled in a variable active duty cycle mode to reduce power and yet maintain motor position information while the main power is off. A lower power battery backup circuit is implemented as a secondary power source, and is automatically brought in operation when the main power supply is disabled. A dedicated control circuit operates during AC power outages, and the circuit average power can be controlled to a minimal rate, based on the rate of change of motor position. The motor can be externally driven, up to a defined limit speed, without losing its actual position information.

Motor tracking control system

The stepper motor controller, implemented as computer software, converts each input pulse into many internal pulses, which internal pulses are used for calculating a command angle during each sampling time interval of operation. The values of the angle commands may vary, from interval to interval, as a function of the input pulse train rate (i.e., the number of new pulses input per interval). The system accesses an internal look-up table to convert vector data into torque values, for driving the motor; if the input pulse rate is sufficiently high to warrant doing so, the look-up table data can be accessed out of sequence.

Stepper drive control using variable step angle

Phase alignment and initialization of a polyphase brushless DC motor are achieved, at standstill, by noting amplitude changes in signals from integral feedback coils while phase coils of the motor, magnetically coupled to the sensor coils, are energized at non-torque producing commutation angles.

Motor initialization method and apparatus

A polyphase brushless DC motor has an integral automatic feedback arrangement affording excellent accuracy and a high degree of magnetic balance. The stator pole elements of the motor are identical and equidistantly spaced, and each is wound with two coils. One coil on each pole element comprises sensor circuitry; the other comprises power circuitry. As a result, all pole elements of the stator are utilized both to produce rotor drive torque and also to generate electrical signals that provide highly accurate rotor-position information.

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Pembroke, MA, United States of America

Hung D Vu