DC Converter for Vehicle Alternator Mitigating Conducted EMI
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Solution Overview
Problem
Conventional vehicle alternators and DC-to-DC converters face limitations in environments with electromagnetic interference (EMI), space constraints, high temperatures, and vibration tolerance, often resulting in insufficient power output or excessive EMI interference.
Innovation Solution
A direct-current (DC) converter for permanent-magnet (PM) alternators featuring pairs of step-down converters arranged in parallel and out of phase to mitigate conducted EMI, with a physical configuration that reduces odd harmonics and uses a liquid cold plate and thermally conductive fins to manage heat and improve thermal conductivity, along with an output filter to mitigate EMI across various harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If existing DC-to-DC converters are used in PM alternators, then output voltage can be regulated, but conducted EMI is generated and power output may be insufficient
Solution Approach 1:
The DC-to-DC converter is divided into multiple parallel converter circuits (at least two) operating at different phases. Each converter circuit processes a portion of the power conversion, allowing the system to maintain high power output while distributing and reducing EMI through phase diversity and parallel architecture.
Solution Approach 2:
The converter circuits are operated in an out-of-phase periodic manner, where switching events of different converter circuits occur at different times within the switching cycle. This periodic phase offset causes EMI signals to cancel each other through destructive interference, reducing conducted EMI while maintaining continuous high power output.
2Power
If higher power levels are used to meet application requirements, then sufficient power output is achieved, but EMI interference increases
Solution Approach 1:
High power conversion is achieved by paralleling multiple converter circuits, each handling a portion of the total power. This segmentation allows the system to scale power output linearly by adding more parallel circuits while each individual circuit generates proportionally less EMI, and the out-of-phase operation further reduces total EMI through cancellation.
Solution Approach 2:
The EMI signals generated by each converter circuit are converted from harmful interference into a beneficial cancellation effect. By carefully controlling the phase relationship between parallel converter circuits, the EMI signals destructively interfere with each other, transforming the harmful EMI that would normally increase with power level into a reduced EMI output that allows high power operation.
3Object-generated harmful factors
If converter circuits are arranged to reduce EMI, then conducted EMI is mitigated, but physical space and configuration complexity increase
Solution Approach 1:
The converter system is segmented into modular parallel circuits that can be independently designed and then systematically combined. This modular segmentation simplifies the overall configuration by allowing repeated use of standardized circuit blocks with controlled phase relationships, reducing design complexity compared to a monolithic approach.
Solution Approach 2:
Multiple converter circuits are merged in parallel with coordinated phase control to achieve EMI reduction. The merging of these circuits shares common components such as input/output filters and control logic, reducing overall component count and physical space requirements compared to having separate independent converters, while maintaining the EMI cancellation benefit.
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 reduces conducted EMI across a range of harmonics, enhances thermal management, and increases power output while maintaining vibration tolerance and space efficiency, improving the quality of DC supply for vehicle electronics.
Implementation Method 1
the two step-down converters in each pair are arranged to be switched out of phase... to mitigate conducted (i.e., conductive, or non-radiative) electromagnetic interference (EMI)
Implementation Method 2
a liquid cold plate and thermally conductive fins to manage heat and improve thermal conductivity
Data Source
AI summary
A direct-current (DC) converter for a permanent-magnet (PM) alternator for a vehicle, the DC converter including one or more pairs of step-down converters that are electrically in parallel operating at a fundamental switching frequency, wherein the two step-down converters in each pair are arranged to be switched out of phase, and wherein the two step-down converters in each pair are arranged adjacent to each other to mitigate conducted electromagnetic interference (EMI).