US 2007/0040529 A1 · Stepping motor control system and method for controlling a stepping motor using closed and open loop controls

Abstract

A stepping motor is driven in both closed-loop and open-loop modes while initiating microstepping after a predetermined threshold velocity has been reached. A feedback device such as an encoder is mounted on the stepping motor shaft and the encoder keeps track of the mechanical position of the rotor. Based on feedback from the encoder, stator phases are activated to maintain a 90° phase advance and produce maximum torque. A lead angle compensation technique is used to advance the motor lead angle, to allow for the excitation currents to reach maximum even at higher speeds. The stepping motor controller employs this strategy in order to produce maximum torque across a wide range of motor speeds and actuator motions.

Claims11

Dependent claims

A stepping motor control system, comprising:

a stepping motor with an encoder connected to said stepping motor;
a current and phase compensation controller, which receives an output from said encoder, wherein said controller implements a lead angle compensation routine, microstepping and full-step motor driving modes during closed-loop driving of said stepping motor, and an open-loop position holding mode when said stepping motor is at rest;
a trajectory generator for sending a velocity motion profile to said current and phase compensation controller, said motion profile having rest, acceleration and constant velocity stages,
wherein when said stepping motor moves at a velocity lower than a predetermined velocity threshold, said stepping motor is operated in the microstepping driving mode, and when said stepping motor moves at a velocity above said velocity threshold, said stepping motor is operated in the full-step driving mode.

1 more element

A method for controlling a stepping motor connected to an encoder, comprising the steps of:

supplying a velocity motion profile, said motion profile having rest, acceleration and constant velocity stages, for driving said stepping motor;
holding said stepping motor in an open-loop position holding control mode when said stepping motor is at rest;
driving said stepping motor in a closed-loop microstepping mode when said stepping motor moves at a velocity lower than a predetermined threshold velocity;
and
driving said stepping motor in a closed-loop full-step mode when said stepping motor moves at a velocity higher than said predetermined velocity threshold.

2 more elements

Dependencies are inferred from the claim text.

Stepping motor control system and method for controlling a stepping motor using closed and open loop controls

Life of this patent

Stepping motor control system and method for controlling a stepping motor using closed and open loop controls

Life of this patent

Abstract

Claims11