Stepping Motor Drive Circuit Current Detection Optimization
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Solution Overview
Problem
Conventional stepping motor drive circuits face challenges in efficiently detecting and controlling drive currents for armature coils, leading to suboptimal torque generation and increased costs due to the need for multiple A/D converters for electric current detection.
Innovation Solution
A motor control apparatus that includes PWM shift units and H-bridge units to adjust PWM pulse signals for armature coils, allowing for efficient detection and control of drive currents by shifting pulse signals and using a single A/D converter for both coils, reducing detection costs and improving torque generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple A/D converters are used for electric current detection in each H-bridge circuit, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the electric current detection functions of multiple H-bridge circuits by connecting their lower common ground sides in parallel and using a single A/D converter to detect currents from all coils. This consolidation reduces the number of A/D converters while maintaining detection capability across all motor phases.
Solution Approach 2:
The single A/D converter is designed to universally detect electric currents from multiple different coils by receiving combined current signals through the parallel-connected lower common ground side. This multi-functional approach allows one converter to perform what previously required multiple dedicated converters.
2Device complexity
If a single A/D converter is used for both coils, then device complexity is reduced, but measurement precision may deteriorate due to simultaneous sampling requirements
Solution Approach 1:
The patent implements periodic time-division multiplexed sampling where the single A/D converter alternates between sampling currents from different coils in sequential time slots. This periodic sampling strategy allows accurate measurement of each coil's current while using only one converter, avoiding the need for simultaneous sampling that would require multiple converters.
Data Source
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AI summary
A motor driving apparatus (100) for causing drive current to flow in first and second armature coils (2, 3) of two-phases to rotate a rotator, includes a drive unit (200) configured to give first and second PWM pulse signals to ends of the first and second armature coils. The drive unit (200) includes a first shift unit (230) configured to, when a difference between pulse widths of the first PWM pulse signals given to the ends of the first armature coil (2) is less than or equal to a first predetermined value, shift forward any one of pulses of the first PWM pulse signals, and a second shift unit (240) configured to, when a difference between pulse widths of the second PWM pulse signals given to the ends of the second armature coil (3) is less than or equal to a second predetermined value, shift backward any one of pulses of the second PWM pulse signals.