Power Converter Bus Bar Thermal Management
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Solution Overview
Problem
In power converters for hybrid and electric vehicles, the heat generated by bus bars poses a reliability risk to capacitor elements due to inadequate heat dissipation and shielding, potentially leading to temperature-related security issues and short-circuits.
Innovation Solution
A power converter design that includes a power semiconductor circuit unit, a smoothing capacitor, a DC-side bus bar connected to the capacitor, and an extending member made of high thermal conductivity material, which directs heat away from the capacitor element without electrical contact, enhancing heat dissipation through a housing cooling surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bus bar is extended to the electrode surface of the capacitor element for electrical connection, then the electrical connection is achieved, but the heat from the bus bar directly affects the capacitor element causing temperature-related reliability issues
Solution Approach 1:
An insulating member is introduced as an intermediary between the bus bar and the capacitor element. This insulating member extends from the bus bar toward the capacitor element but does not contact the electrode surface, providing both electrical insulation and thermal isolation while maintaining the necessary electrical connection through the capacitor terminal
Solution Approach 2:
The bus bar structure is segmented into distinct functional portions: a main body portion for electrical connection and heat dissipation, and an extending member that provides insulation and thermal shielding without direct contact with the capacitor element's electrode surface
2Reliability
If heat dissipation measures are added to protect the capacitor element, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The insulating member serves multiple functions simultaneously: it provides electrical insulation between the bus bar and capacitor element, acts as a thermal shield to reduce heat transfer, and maintains the structural positioning of components. This multi-functionality avoids the need for separate heat dissipation structures
Solution Approach 2:
The insulating member acts as a mediator that combines insulation and heat shielding functions in a single component, simplifying the overall structure while effectively protecting the capacitor element from thermal effects
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 design improves the reliability of the capacitor element by effectively dissipating heat generated by the bus bar, preventing temperature-related deterioration and short-circuits, thereby ensuring stable operation.
Implementation Method 1
an extending member that is formed between the case and the capacitor element and formed from the main body portion toward the bottom of the capacitor housing portion
Implementation Method 2
a capacitor element that smooths the DC power
Implementation Method 3
a power semiconductor circuit unit that performs an operation of converting DC power into AC power
Data Source
AI summary
An object of the present invention is to ensure the reliability of a capacitor element by appropriately securing a heat path around the capacitor element.A power converter according to the present invention includes: a power semiconductor circuit unit that converts DC power into AC power; a capacitor element that smooths the DC power; a DC-side bus bar that transmits the DC power; a capacitor terminal that is connected to an electrode surface of the capacitor element and to the DC-side bus bar; and a case that forms a capacitor housing portion for housing the capacitor element, in which the DC-side bus bar has: a power supply-side terminal; a main body portion that is arranged at a position facing a bottom of the capacitor housing portion with the capacitor element interposed therebetween; and an extending member that is formed between the case and the capacitor element and formed from the main body portion toward the bottom of the capacitor housing portion, and that does not contact the electrode surface.