Reactor Magnetic Core Reinforcement for Noise Suppression
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Solution Overview
Problem
Reactor noise during operation is a significant issue due to resonance between the drive frequency of the electric current and the natural frequency of the magnetic core, particularly in power conversion devices for hybrid and electric automobiles, where the drive frequency falls within a range that causes audible noise.
Innovation Solution
Incorporating a non-magnetic reinforcing member between the winding portions of the reactor's coil and magnetic core, with an axial rigidity of 2×10^7 N/m or more, to increase the natural frequency of the magnetic core and prevent resonance with the drive frequency, thereby reducing noise. This is achieved by using materials with high Young's modulus and thermal conductivity, such as aluminum or its alloys, and arranging the reinforcing member to suppress expansion and contraction of the magnetic core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the drive frequency is within the audible range (20 Hz to 20 kHz) for power conversion devices in hybrid and electric automobiles, then the reactor can perform its voltage conversion function, but resonance occurs between the drive frequency and the natural frequency of the magnetic core, causing noise
Solution Approach 1:
The patent changes the physical parameters of the magnetic core by adding a reinforcing member, which increases the natural frequency of the magnetic core. This parameter change shifts the natural frequency away from the drive frequency range (20 Hz to 20 kHz), preventing resonance and reducing noise while maintaining the voltage conversion function.
Solution Approach 2:
The patent uses a composite structure by combining the magnetic core with a reinforcing member (which may be made of non-magnetic material such as resin or metal). This composite structure increases the rigidity and natural frequency of the magnetic core, thereby preventing resonance with the drive frequency and reducing noise.
2Object-generated harmful factors
If a reinforcing member is added to increase the natural frequency of the magnetic core, then noise is reduced, but the device complexity increases
Solution Approach 1:
The reinforcing member serves multiple functions: it increases the natural frequency of the magnetic core to prevent resonance, provides structural support to the coil assembly, and can contribute to thermal management. By combining multiple functions in a single component, the patent reduces overall device complexity despite adding the reinforcing member.
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 suppresses noise caused by vibration by ensuring the natural frequency of the magnetic core is significantly higher than the drive frequency, thereby reducing noise levels and stabilizing the magnetic characteristics of the reactor.
Implementation Method 1
If the natural frequency of the magnetic core is close to this drive frequency, resonance will occur and noise will thus increase
Implementation Method 2
the reactor may vibrate due to magnetostriction or electromagnetic attraction caused by the occurrence of a magnetic flux in a magnetic core
Implementation Method 3
A reactor is driven by exciting a coil through the application of an electric current of a predetermined frequency to the coil
Implementation Method 4
the reactor may vibrate due to magnetostriction or electromagnetic attraction caused by the occurrence of a magnetic flux in a magnetic core
Data Source
AI summary
Provided is a reactor including a coil having a pair of winding portions; and a ring-shaped magnetic core, the magnetic core including: a pair of inner core portions arranged inside of the winding portions; and a pair of outer core portions respectively arranged outside of one end and outside of another end in an axial direction of the winding portions, the reactor including a non-magnetic reinforcing member that is arranged between the pair of winding portions and is coupled to the inner end surfaces of the pair of outer core portions. An axial rigidity of the reinforcing member is 2×107 N/m or more. Here, the axial rigidity is a value obtained by multiplying the cross-sectional area of the reinforcing member perpendicular to the axial direction of the winding portions and the Young's modulus of the reinforcing member, and dividing the result by the length of the reinforcing member.