Inverter Capacitor Layout for Compact and Noise-Stable Power Conversion
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Solution Overview
Problem
Existing power conversion devices face challenges in miniaturization and stable operation due to increased size and noise interference from electrolytic capacitors in voltage doubler rectifier circuits, leading to potential malfunctions in weak electric signals.
Innovation Solution
The capacitors are arranged such that their axial direction is parallel to the substrate plane, with the high-side potential capacitor positioned farther from the control circuit, and a capacitor board is used for fixation, reducing size and noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the capacitance of the electrolytic capacitor is increased to reduce heat generation in the voltage doubler rectifier circuit, then the reliability is improved, but the volume of the electrolytic capacitor increases
Solution Approach 1:
The patent divides a single large-capacitance electrolytic capacitor into multiple smaller-capacitance electrolytic capacitors connected in parallel. This segmentation reduces the volume of each individual capacitor while maintaining the total capacitance required to reduce heat generation, thereby resolving the contradiction between reliability and volume.
2Ease of manufacture
If the electrolytic capacitor is mounted with its height direction perpendicular to the substrate plane, then the ease of manufacture is improved, but the area of stationary object increases
Solution Approach 1:
The patent changes the mounting orientation of the electrolytic capacitors from the height direction (perpendicular to substrate) to the width direction (parallel to substrate). This dimensional change allows the capacitors to be arranged in a plane, reducing the overall footprint area while maintaining ease of manufacture through standard surface-mount techniques.
3Area of stationary object
If the first electrolytic capacitor is positioned closer to the control circuit, then the area of stationary object is reduced, but the object-affected harmful factors increase due to noise interference
Solution Approach 1:
The patent extracts the first electrolytic capacitor (connected to the high-side potential node) from its conventional position near the control circuit and relocates it to a position farther away. This separation removes the harmful noise interference from the control circuit area, while the overall layout is optimized to minimize the area occupied by the power conversion device.
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 arrangement enables miniaturization and stable operation by minimizing size increase and noise propagation, ensuring compatibility between miniaturization and operational stability.
Implementation Method 1
a first electrolytic capacitor connected between a high-side potential node of a DC voltage and an AC power source and a second electrolytic capacitor connected between the AC power source and a low-side potential node of the DC voltage
Implementation Method 2
A full-wave rectifier circuit is used when the AC voltage is more than 200 V and a voltage doubler rectifier circuit is used when the AC voltage is about 100 V to 120 V
Data Source
AI summary
To provide a power conversion device capable of making miniaturization and a stable operation compatible with each other. Therefore, a smoothing capacitor 21 outputs a high-side potential of a DC voltage, and a smoothing capacitor 22 is connected in series with the smoothing capacitor 21 and outputs a low-side potential of the DC voltage. An inverter circuit 103 converts the DC voltage output from the smoothing capacitors 21 and 22 into an AC voltage. A control circuit 104 controls the inverter circuit 103. The inverter circuit 103 is mounted on a main circuit board 61. Each of the smoothing capacitors 21 and 22 is arranged such that an axial direction, which defines its longest size, is substantially parallel to a plane direction of the main circuit board 61. The smoothing capacitor 21 is arranged at a position farther away from the control circuit 104 than the smoothing capacitor 22.