Bipolar Stepper Motor Drive Stabilization via Regenerative Braking
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Solution Overview
Problem
Bipolar stepper motor driving devices face instability due to deteriorating followability, leading to phase advance or delay, resulting in a step-out state during motor operation, as existing systems lack mechanisms to stabilize the driving torque and speed.
Innovation Solution
A bipolar stepper motor driving device is designed with H-bridge circuits, a current detector, and a re-turning-on instruction unit to stabilize the motor operation by detecting changes in current and switching stator coils into a short-circuited state when the absolute value of reverse current decreases below a threshold, preventing rotor swinging and maintaining a stable rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If open-loop control is used for bipolar stepper motor driving, then the control system is simple, but the motor operation becomes unstable due to deteriorating followability and phase shift
Solution Approach 1:
The patent implements feedback control by detecting the current flowing through the stator coil and using this information to control the switching timing of the H-bridge circuit. The controller adjusts the switch turning-on timing based on the detected current value, creating a closed-loop control system that maintains stable motor operation while preventing step-out states.
2Speed
If the H-bridge circuit is turned off immediately after energization, then the switching speed is high, but rotor swinging occurs due to insufficient damping of reverse current
Solution Approach 1:
The patent applies preliminary action by keeping the H-bridge circuit in the on-state for a predetermined period after the current reaches the target value. This preliminary continuation of energization allows the reverse current to be properly damped before switching off, preventing rotor swinging while maintaining high switching speed capability.
Solution Approach 2:
The patent implements dynamic control by adjusting the switch turning-on timing based on the detected current value. The controller dynamically modifies the energization period according to real-time current conditions, optimizing both switching speed and rotor stability adaptively during motor operation.
3Stability of the object's composition
If the energization period is extended to prevent rotor swinging, then rotor stability improves, but the switching frequency decreases and productivity is reduced
Solution Approach 1:
The patent changes the parameter of energization duration dynamically based on detected current conditions. By adjusting the timing parameters adaptively rather than using fixed extended periods, the system maintains rotor stability while minimizing the impact on switching frequency and overall productivity.
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
The solution ensures stable operation by preventing rotor vibration and maintaining a stably-rotating state through regenerative braking, effectively addressing the instability issues in bipolar stepper motor driving devices.
Implementation Method 1
a current detector (5r, 6r) configured to detect current flowing in each of the plural-phase stator coils
Implementation Method 2
In the stator coil, a counter electromotive force is generated due to self-inductance
Implementation Method 3
the MOS transistors 5a to 5d and 6a to 6d, which serve as switching elements, turn on and off in response to gate signals
Data Source
AI summary
A bipolar stepper motor driving device drives a stepper motor including stator coils having plural phases. The bipolar stepper motor driving device includes H-bridge circuits, a current detector, a control circuit, and a re-turning-on instruction unit. The H-bridge circuits are provided correspondingly to the phases of the respective stator coils. The current detector detects current flowing in the stator coils. The control circuit executes drive control of the H-bridge circuits. The re-turning-on instruction unit commands the control circuit to switch into a short-circuited state a stator coil which has shifted from an energized state to an off-state among the stator coils, on a condition that an absolute value of a reverse current detected by the current detector has changed from a value larger than a threshold current value to a value smaller than the threshold current value.