Dual Inverter Neutral Separation for Compact AC Power Conversion
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Solution Overview
Problem
Existing single-phase three-wire inverters require large capacitors to balance voltage differences between lines, leading to increased size and difficulty in reducing the inverter's dimensions.
Innovation Solution
A power conversion device with dual inverter circuits and a controller that separates the neutral point, allowing independent control of each inverter circuit to generate single-phase two-wire and three-wire AC power, reducing the need for large capacitors and enabling a more compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If smoothing capacitors with sufficiently large capacitance are used to suppress voltage difference, then voltage balance between AC power lines is improved, but device size increases
Solution Approach 1:
The patent divides the single-phase three-wire inverter into two separate single-phase two-wire inverter circuits (first inverter circuit and second inverter circuit) that operate in parallel. Each inverter circuit has its own isolated DC/DC converter unit and smoothing capacitor (C1a, C1b for first circuit; C2a, C2b for second circuit). This segmentation allows each capacitor to handle only half the total power, reducing individual capacitance requirements while maintaining voltage balance through the parallel configuration and neutral point connection.
2Power
If a single-phase three-wire inverter configuration is used to provide AC power to devices, then power delivery capability is improved, but load imbalance causes voltage differences requiring large capacitors
Solution Approach 1:
The patent applies local quality by creating two separate inverter circuits with independent DC/DC converter units and smoothing capacitors. Each circuit locally handles a portion of the power delivery, with the first circuit serving one phase and the second circuit serving the other phase. This local化处理 allows each capacitor to be sized appropriately for its specific power handling requirements, reducing the need for oversized capacitors while maintaining overall system power delivery capability.
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 balances voltage differences without large capacitors, allowing for a smaller inverter size and stable AC power output even with imbalanced loads.
Implementation Method 1
an isolated DC/DC converter unit that converts the power output from the power source
Implementation Method 2
a smoothing capacitor that smooths a DC power output by the isolated DC/DC converter unit
Implementation Method 3
a full-bridge inverter unit that converts a DC power generated across opposite ends of the smoothing capacitor to generate a single-phase two-wire AC power
Implementation Method 4
The output inductors L1 to L3 are each arranged on the first to third lines to convert the AC power output from the full-bridge inverter unit X20 into sine waves
Data Source
AI summary
A power conversion device includes an inverter and a controller that controls the inverter. The inverter includes a first inverter circuit and a second inverter circuit that are connected in parallel to a power source. A first output terminal of a full-bridge inverter unit and a first terminal are connected to each other. A second output terminal of the full-bridge inverter unit and a second terminal are connected to each other. The second output terminal of the full-bridge inverter unit and the first output terminal of the full-bridge inverter unit are connected to each other at a connecting point. The connecting point and a neutral point terminal are connected to each other.