Stepping Motor Control Device Preventing Spontaneous Position Drift
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Solution Overview
Problem
Stepping motors used in actuators can spontaneously move away from an end stop position due to internal strain, leading to uncontrollable position management and potential deviations from the target position, especially when they become out of step, causing issues like incomplete closure in air conditioner flaps.
Innovation Solution
A motor control device that includes a detecting unit to identify when a stepping motor is out of step and a reverse rotating unit to rotate the motor in a reverse direction by a number of steps alleviating the stress before spontaneous movement occurs, followed by re-driving the motor in the original direction with reduced torque to prevent further deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motor is stopped immediately after out-of-step detection, then the motor can be held at the end stop position, but the actuator may spontaneously move away from the end stop due to internal strain
Solution Approach 1:
The patent applies preliminary action by rotating the motor in reverse direction for a predetermined number of steps before spontaneous movement occurs. This reverse rotation preemptively releases the internal strain accumulated in the actuator, preventing the spontaneous movement that would otherwise occur after stopping at the end stop position.
2Stability of the object's composition
If the motor rotates reversely to alleviate strain, then spontaneous movement is prevented, but the motor may move away from the target position
Solution Approach 1:
The patent applies partial action by limiting the reverse rotation to a predetermined small number of steps (e.g., 1-3 steps) rather than a full reversal. This partial reverse rotation is sufficient to release internal strain while minimizing displacement from the target position, maintaining position accuracy.
3Productivity
If the motor is re-driven in the original direction, then the actuator returns to normal operation, but the motor may become out of step again due to residual strain
Solution Approach 1:
The patent applies continuity of useful action by immediately re-driving the motor in the original rotation direction after the brief reverse rotation. This continuous operation sequence (reverse rotation followed immediately by forward rotation) ensures the actuator returns to normal operation without interruption while the strain has been alleviated, preventing further out-of-step conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents the stepping motor from spontaneously rotating away from the end stop position, maintaining control and accuracy by alleviating internal stress and ensuring the actuator remains at the intended position.
Implementation Method 1
a back electromotive voltage measuring unit configured to measure a back electromotive voltage
Data Source
AI summary
There is provided a motor control device controlling an energizing state of a coil of each phase for driving a stepping motor having multiple phase coils. The motor control device includes a detecting unit configured to detect whether the stepping motor is out of step, and a reverse rotating unit configured, when the detecting unit detects that the stepping motor is out of step, to rotate the stepping motor in a second rotation direction reverse to a first rotation direction, which is a rotation direction of the stepping motor before detecting out-of-step, by a number of steps with which a stress received by the stepping motor is alleviated, before the stepping motor spontaneously rotates in the second direction.