Interference Suppression System for Brushless DC Motor Drives
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Solution Overview
Problem
Conventional drill hammers with brushless DC motors experience interference currents due to MOSFET transistors, which impair electromagnetic compatibility, leading to compatibility issues and potential damage from high-frequency oscillations.
Innovation Solution
An interference suppression system with a core having specific through-openings and a compact design that guides connecting lines through these openings, optimizing magnetic flux and attenuating both common-mode and push-pull interferences, ensuring robustness against vibration and easy production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MOSFET transistors are used in the control device to drive the brushless DC motor, then the motor can be controlled efficiently, but interference currents occur due to inductance switching that impair electromagnetic compatibility
Solution Approach 1:
A common-mode choke is introduced as an intermediary component between the control device and the motor windings. This choke suppresses the high-frequency interference currents generated by MOSFET switching while allowing the useful motor control signals to pass through. The choke acts as a mediator that filters out the harmful electromagnetic interference without affecting the efficient motor operation.
2Reliability
If a conventional interference suppression component is added to the drive system, then electromagnetic compatibility can be improved, but the device complexity and space requirements increase
Solution Approach 1:
The common-mode choke is integrated into the existing drive system architecture by routing the motor connecting lines through its through-openings. This merging approach combines the interference suppression function with the existing motor connection structure, avoiding the need for separate, additional components and minimizing system complexity while maintaining electromagnetic compatibility.
3Reliability
If the core has multiple through-openings for connecting lines, then interference suppression effectiveness is improved, but the manufacturing complexity increases
Solution Approach 1:
The core is designed with multiple discrete through-openings (first, second, and third through-openings) that are positioned to receive individual motor connecting lines. This segmentation allows each through-opening to be precisely positioned for optimal interference suppression while maintaining a modular structure that can be manufactured using standard techniques. The segmented design enables effective suppression of interference currents in multiple spatial directions without requiring complex monolithic structures.
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 effectively attenuates interference currents, maintaining electromagnetic compatibility throughout the tool's lifespan, ensuring reliable operation and compliance with EMC regulations while being resistant to vibration and easy to manufacture and assemble.
Implementation Method 1
the first through-opening is situated parallel to the second through-opening and parallel to the third through-opening... when a common-mode interference signal is introduced into the first through third connecting line, it is ensured that a magnetic flux flows optimally within the core
Data Source
AI summary
An interference suppression system, a drive having such a suppression system, and a handheld power tool having such a drive, the interference suppression system including a core, the core having exactly one first through-opening, one second through-opening, and one third through-opening, a first segment of a first connecting line of the drive being situated in the first through-opening, a second segment of a second connecting line of the drive being situated in the second through-opening, and a third segment of a third connecting line of the drive being situated in the third through-opening.