Motor Controller Grounding via Direct Connection Line
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Solution Overview
Problem
Existing motor control systems that separate the motor and motor controller face challenges in effectively reducing noise generated by common mode current, as the noise reduction methods used in integrated systems are not applicable when the motor and controller are provided as separate entities.
Innovation Solution
A motor control apparatus that includes a motor with a metal housing and a separate motor controller, where the motor is connected to the motor controller through a conductive film and a connection line, allowing the common mode current to reflux directly between the motor and the motor controller without leaking to the motor controller's housing, thereby reducing the loop area of the current route and minimizing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the motor controller and motor are provided integrally as a common housing, then the noise reduction effect is improved, but the adaptability to different ambient conditions and installation requirements deteriorates
Solution Approach 1:
The patent divides the motor controller and motor into separate housings rather than integrating them into a common housing. The motor controller is housed in a separate controller housing while the motor has its own motor housing, allowing independent placement and adaptation to different installation environments while maintaining the noise reduction benefits through separate grounding paths.
Solution Approach 2:
The patent introduces a connection line as an intermediary element that directly connects the motor housing to the circuit portion of the motor controller, bypassing the controller housing. This intermediary connection enables the separate housing configuration to achieve the same noise reduction effect as integrated designs by providing a direct path for common mode current reflux.
2Adaptability or versatility
If the motor controller and motor are provided separately, then the adaptability to different ambient conditions is improved, but the noise reduction effect deteriorates
Solution Approach 1:
The connection line serves as a direct intermediary path that bridges the motor housing and circuit portion without routing through the controller housing. This direct intermediary connection maintains the noise reduction effect by ensuring common mode current reflux occurs through a minimal loop area, even though the controller and motor are physically separated into different housings.
Solution Approach 2:
The patent applies local quality by creating a specialized direct connection path specifically for the common mode current reflux between the motor housing and circuit portion. This localized direct connection differs from the general power and signal connections, providing targeted noise reduction functionality at the specific location where common mode current generation occurs.
3Object-affected harmful factors
If the connection line directly connects the motor housing to the circuit portion without through the controller housing, then the loop area is reduced and noise is minimized, but the device complexity increases
Solution Approach 1:
The connection line performs multiple functions: it serves as both the direct reflux path for common mode current and as a structural connection element between the motor and controller components. By making this single connection line multi-functional, the patent avoids adding separate dedicated reflux paths, thereby minimizing the increase in device complexity while achieving noise reduction.
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
This configuration effectively reduces the noise generated by common mode current by ensuring the current flows directly between the motor and motor controller, minimizing the loop area and noise impact, even when the motor and controller are separate entities.
Implementation Method 1
A connection line directly connects the metal housing of the motor and the circuit portion of the motor controller without through the housing of the motor controller
Implementation Method 2
Since a portion between an electric motor and a motor housing is coupled through a stray capacity, when potential of the electric motor changes according to a switching operation of a motor controller
Data Source
AI summary
A motor control apparatus includes a motor, a motor controller, and a connection line. The motor is mounted to a vehicle and has a metal housing. The motor controller is separately provided with the motor, includes a housing and a circuit portion, is connected to the motor through a load line, and drives the motor by a drive current transmitted through the load line. A ground line of the circuit portion is connected to a body of the vehicle as a body earth. The connection line directly connects the metal housing of the motor and the circuit portion of the motor controller without through the housing of the motor controller.