Stepper Motor Phase Correction for Closed- to Open-Loop Switching
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Solution Overview
Problem
In stepping motors, switching from closed-loop control to open-loop control can cause fluctuations in drive current phase, leading to vibrations and instability.
Innovation Solution
A motor control device with a current control unit that manages current supply using either open-loop or closed-loop control, and a rotational position correction unit that adjusts phase differences to stabilize the current phase during control switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If closed-loop control is used for high-speed rotation, then stable operation is achieved, but hunting vibration occurs when stopping
Solution Approach 1:
The control system dynamically switches between closed-loop control and open-loop control based on the operational state. During high-speed rotation, closed-loop control is used for stability. When stopping, the system transitions to open-loop control to prevent hunting vibration, making the control approach adaptive to the current operational phase.
Solution Approach 2:
The invention changes the control parameter from closed-loop to open-loop control mode based on the rotational state. This parameter change allows the system to optimize performance for different operational conditions - using feedback control for stability during rotation and open-loop control for smooth stopping.
2Object-generated harmful factors
If switching from closed-loop control to open-loop control, then hunting vibration is reduced, but fluctuations in drive current phase occur
Solution Approach 1:
The system performs preliminary action by calculating the phase difference between closed-loop and open-loop control modes before switching occurs. This advance calculation allows the system to prepare for the transition and minimize disruptions to the drive current phase when switching control modes.
Solution Approach 2:
The invention introduces an intermediary calculation step that determines the phase difference between control modes. This intermediary phase difference calculation acts as a bridge, allowing smooth transition between closed-loop and open-loop control while maintaining drive current phase stability.
3Device complexity
If phase difference between control modes is not corrected, then control switching is simple, but vibrations occur due to drive current phase fluctuations
Solution Approach 1:
The invention replaces complex mechanical vibration suppression mechanisms with a computational approach. Instead of adding physical damping or mechanical components, the system uses phase difference calculations and control mode transitions to suppress vibrations, achieving vibration reduction through software-based control strategies.
Data Source
AI summary
To suppress a fluctuation in phase of a drive current when trying to switch between a feedback control and an open-loop control. A motor control device includes a current control unit controlling a current by either an open-loop control or a closed-loop control, and a rotational position correction unit correcting a second phase difference based on a first phase difference, the first phase difference being a difference between a rotational position of a rotor in a state where the current control unit controls the current by the closed-loop control and a target rotational position of the rotor, and the second phase difference being a difference between a rotational position in the closed-loop control and a rotational position in the open-loop control when the current control unit switches from the closed-loop control to the open-loop control.