Motor Neutral-Point Filter Circuit for Overcurrent Protection
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Solution Overview
Problem
Existing motor configurations with filter elements to suppress potential fluctuations are vulnerable to overcurrent damage, which can lead to circuit damage and inefficiencies.
Innovation Solution
A motor design that includes a stator with plural windings connected at a neutral point, a switching circuit to generate a rotating magnetic field, a resistor for current detection between the switching circuit and grounding, and a filter element between the neutral point and the resistor, which is grounded through the current detection resistor to reduce potential fluctuations and prevent overcurrent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a filter element is added to suppress potential fluctuations at the neutral point, then electromagnetic wave noise is reduced, but the filter element becomes vulnerable to overcurrent damage
Solution Approach 1:
The patent introduces a current detection resistor as an intermediary element between the filter element and ground. This resistor limits the current flowing through the filter element, preventing overcurrent damage while maintaining the filter's noise suppression function. The resistor acts as a protective mediator that safeguards the filter element without compromising its electromagnetic interference reduction capability.
2Stability of the object's composition
If the filter element is directly grounded to reduce potential fluctuation, then noise suppression is improved, but overcurrent can damage the filter element
Solution Approach 1:
The current detection resistor serves as a protective intermediary in the grounding path of the filter element. By placing the resistor between the filter element and ground, the system achieves both stable potential at the neutral point (through proper filtering) and protection against overcurrent (through the current-limiting resistor), resolving the contradiction between stability and reliability.
3Reliability
If a current detection resistor is added between the switching circuit and ground, then overcurrent protection is enabled, but circuit complexity increases
Solution Approach 1:
The current detection resistor serves multiple functions simultaneously: it limits current to protect the filter element from overcurrent damage, enables overcurrent detection for system protection, and provides a reference for potential measurements. By making this single component multi-functional, the patent achieves reliable overcurrent protection without proportionally increasing circuit complexity.
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 motor effectively suppresses overcurrent damage to the filter element and prevents further circuit damage by detecting excessive currents and stopping the switching circuit operation when thresholds are exceeded, ensuring stable operation.
Implementation Method 1
a filter element that reduces a fluctuation in potential at the neutral point, the filter element being disposed between the neutral point and the resistor for current detection
Implementation Method 2
a switching circuit that generates a rotating magnetic field around the stator by switching of a power supply to the plural windings
Implementation Method 3
a rotor that rotates in response to the rotating magnetic field generated around the stator
Data Source
AI summary
A motor including: a stator including plural windings that form coils and are connected together at a neutral point; a switching circuit that generates a rotating magnetic field around the stator by switching of a power supply to the plurality of windings; a rotor that rotates in response to the rotating magnetic field generated around the stator; a resistor for current detection that detects a current in the switching circuit and that is disposed between the switching circuit and a grounding point; and a filter element that reduces a fluctuation in potential at the neutral point, the filter element being disposed between the neutral point and the resistor for current detection and being grounded at the grounding point via the resistor for current detection.