Motor Control Device Grounding Output Lines to Reduce Electromagnetic Noise
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Solution Overview
Problem
Existing motor controlling devices face challenges in reducing electromagnetic noise from signal wiring that cannot be grounded, leading to increased manufacturing costs and vehicle weight, affecting fuel efficiency.
Innovation Solution
A motor controlling device with a drive circuit of H-bridge type using field-effect transistors (FETs) that lowers the output lines to ground potential when not operating the motor, reducing electromagnetic noise by secondary radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If signal wiring is shielded to reduce electromagnetic noise, then noise resistance is improved, but manufacturing cost increases and vehicle weight increases
Solution Approach 1:
The patent applies equipotentiality by connecting the output lines to ground potential through switching elements when the motor is not operating. This creates an equipotential state with the ground, eliminating potential differences that would cause electromagnetic radiation, thereby reducing noise without requiring additional shielding materials that would increase weight.
Solution Approach 2:
The patent changes the electrical potential parameter of the output lines dynamically. When the motor is not operating, the switching elements connect the output lines to ground, changing their potential from floating to grounded state. This parameter change reduces electromagnetic noise without adding physical shielding structures, avoiding increased vehicle weight.
2Object-affected harmful factors
If signal wiring is shielded to reduce electromagnetic noise, then noise resistance is improved, but manufacturing cost increases
Solution Approach 1:
The patent uses equipotentiality to reduce noise by grounding output lines through existing switching elements in the H-bridge circuit. This approach utilizes components already present in the system rather than adding separate shielding materials, thereby reducing manufacturing cost while maintaining noise resistance.
Solution Approach 2:
The switching elements in the H-bridge circuit serve dual functions: motor control and noise reduction. When the motor is not operating, these same switching elements connect the output lines to ground, providing noise reduction as a self-service function without requiring additional components, thus avoiding increased manufacturing cost.
3Object-affected harmful factors
If switching elements are used to ground output lines, then electromagnetic noise is reduced, but device complexity increases
Solution Approach 1:
The switching elements in the H-bridge circuit perform multiple functions: motor control during operation and noise reduction by grounding output lines when the motor is not operating. This multi-functionality reduces device complexity compared to adding separate components or control systems dedicated solely to noise reduction.
Solution Approach 2:
The existing switching elements serve themselves to provide noise reduction functionality. When the motor stops operating, the switching elements automatically connect the output lines to ground, providing noise reduction without requiring additional control circuits or complex management systems.
Data Source
AI summary
A motor controlling device configured to control an on-board motor is provided, which includes an H-bridge type drive circuit comprised of first switching elements and configured to drive the on-board motor, and a controlling circuit configured to control the on-board motor by controlling the drive circuit, the controlling circuit carrying out an ON control of one of the first switching elements connected to ground, when not operating the on-board motor.