Laminated Capacitor Module Bus Bar Inductance Reduction
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Solution Overview
Problem
Power conversion devices in hybrid and electric vehicles face challenges in achieving higher current and voltage while minimizing size due to surge voltage issues, which require lower inductance at bus bars to protect power semiconductor elements.
Innovation Solution
A capacitor module with laminated bus bars and capacitor elements, where the positive and negative electrodes are positioned to achieve a magnetic flux-canceling effect, reducing inductance and allowing for higher current and voltage handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inductance at bus bars is reduced to suppress surge voltage, then the power semiconductor elements can operate at higher current and voltage, but the device size cannot be further minimized
Solution Approach 1:
The bus bar structure transitions from a planar arrangement to a three-dimensional laminated configuration where multiple bus bar plates are stacked and interleaved. This dimensional change allows the magnetic flux-canceling effect to operate over a wider area without increasing the overall device footprint, thereby reducing inductance while maintaining compact size.
Solution Approach 2:
The positive and negative bus bar plates are merged into a single laminated assembly where they are interleaved and closely positioned. This merging enables the magnetic flux generated by currents in adjacent plates to cancel each other out, achieving lower inductance and better surge voltage suppression in a compact structure.
2Volume of moving object
If the power conversion device is miniaturized to improve installation flexibility, then the space in the engine compartment is reduced, but the inductance at bus bars increases causing surge voltage issues
Solution Approach 1:
The bus bar structure utilizes a three-dimensional laminated arrangement where multiple plates are stacked and interleaved. This dimensional configuration maximizes the magnetic flux-canceling effect within a compact volume, enabling surge voltage suppression without increasing device size.
Solution Approach 2:
The capacitor elements are strategically positioned with their electrodes disposed closer to specific bus bar plates to optimize the magnetic flux-canceling effect in critical areas. This local optimization ensures effective surge voltage suppression in the high-stress regions of the power conversion device.
3Power
If higher current and voltage are achieved through power conversion, then the power output is increased, but momentary spiking of voltage occurs due to inductance
Solution Approach 1:
The positive and negative bus bar plates are merged into an interleaved laminated assembly, creating a structure where magnetic flux from adjacent plates cancels each other. This merging achieves low inductance that prevents voltage spiking, enabling higher power output with improved voltage stability.
Solution Approach 2:
The inductance parameter of the bus bar structure is fundamentally changed through the laminated configuration. By transforming the geometric arrangement from conventional to laminated, the inductance value is reduced, which directly suppresses voltage spiking and enables stable high-power operation.
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 enables the power conversion device to handle greater currents and higher voltages, leading to miniaturization and improved reliability by suppressing surge voltage and reducing the required voltage-withstand value of power semiconductor elements.
Implementation Method 1
lower inductance is achieved by allowing the magnetic flux-canceling effect (an inductance reducing effect through mutual inductance) attributable to the same-phase bidirectional currents flowing in close proximity to each other
Data Source
AI summary
In a power conversion device according to the present invention, a capacitor module, includes a first capacitor element; a second capacitor element; a positive pole-side bus bar; and a negative pole-side bus bar disposed in a laminated state, in which the positive pole-side bus bar and the negative pole-side bus bar are laminated via an insulating member. The first capacitor element includes a first body portion, a first positive pole-side electrode, and a first negative pole-side electrode. The second capacitor element includes a second body portion, a second positive pole-side electrode, and a second negative pole-side electrode. The first capacitor element is disposed so that the first positive pole-side electrode assumes a position closer to the second negative pole-side electrode than to the second positive pole-side electrode and faces the second negative pole-side electrode; and a laminate portion formed with the positive pole-side bus bar and the negative pole-side bus bar continues up to a point over a space where the first positive pole-side electrode and the second negative pole-side electrode face each other.