EV Drive Shaft Noise Cancellation Using Choke Coil Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing drive devices for electrified vehicles face challenges in suppressing relatively large electromagnetic noise transmission to the drive wheels through the power transmission path while avoiding device enlargement, particularly due to shaft voltage discharges and inverter switching.
Innovation Solution
A drive device equipped with a shaft voltage sensor and choke coils that detect and cancel electromagnetic noise by applying current to the choke coils when predetermined pulsations are detected, using an application control device to manage the choke coils and suppress noise transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a separate brush chamber is provided outside the gear case to reduce electromagnetic noise, then noise suppression is improved, but the device size is enlarged
Solution Approach 1:
The patent merges the brush chamber with the gear case inner chamber by forming a through-hole in the gear case that communicates the inner chamber with the external environment. This allows the brush chamber to function separately for noise suppression while sharing space with the existing gear case structure, avoiding device enlargement.
Solution Approach 2:
The gear case is designed to serve multiple functions: it houses the gear mechanism, provides structural support, and incorporates a through-hole that enables electromagnetic noise suppression by allowing the brush chamber to communicate with the inner chamber. This multi-functionality eliminates the need for separate noise suppression components.
2Object-affected harmful factors
If ground connection bodies with sliding contact brushes are used to discharge shaft voltage, then electromagnetic noise is reduced, but device complexity increases
Solution Approach 1:
The sliding contact brush automatically maintains electrical contact with the counter shaft through its own weight and spring force, providing self-service ground connection. The brush moves with the shaft during thermal expansion and mechanical displacement, eliminating the need for complex adjustment mechanisms while maintaining effective shaft voltage discharge.
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
Effectively suppresses electromagnetic noise transmission to the drive wheels, preventing device enlargement by detecting and canceling noise through the power transmission path, thus maintaining compactness.
Implementation Method 1
The choke coil 48a, 48b is attached to each drive shaft 42a, 42b. An application control device applies a current to the choke coil to cancel at least a part of electromagnetic noise transmitted to the drive wheels through the power transmission path
Data Source
AI summary
A drive device for an electrified vehicle includes a motor having a rotor attached to a motor shaft and a stator wound with a motor coil, an inverter that drives the motor by switching of a switching element, a shaft voltage sensor that detects a shaft voltage of the motor shaft, a choke coil attached to a power transmission path from the motor shaft to drive wheels, and an application control device that applies a current to the choke coil to cancel at least a part of electromagnetic noise transmitted to the drive wheels through the power transmission path when a predetermined pulsation of the shaft voltage is detected based on a detection value of the shaft voltage sensor.