Phase-Shifted Multilevel Power Converter for Low-THD AC Output
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power conversion technologies, such as solar inverters and battery coupled inverters/chargers, face challenges in achieving low cost, high efficiency, and compliance with environmental and safety standards, particularly in generating desired voltage and current waves at low voltage and frequency while minimizing total harmonic distortion (THD), electromagnetic interference (EMI), and leakage current.
Innovation Solution
A low voltage, low frequency multi-level power converter (LV LF MLPC) system that uses low voltage, high performance components and drives power devices at low frequency to generate a semi-sine wave output, eliminating the need for expensive bus connectors and high voltage components, and incorporating phase-shifting inverters to create a utility-rated voltage wave with reduced THD and EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high voltage and high frequency switching components are used to achieve compact size and high power density, then power conversion efficiency and energy density improve, but cost increases, THD increases, EMI increases, and leakage current increases
Solution Approach 1:
The patent divides the power conversion system into multiple low voltage inverters (e.g., 14 inverters operating at 24.2V each) connected in series to achieve the desired output voltage (e.g., 240Vrms). Each inverter operates independently at low voltage and low frequency, avoiding the harmful effects of high voltage switching while maintaining high power conversion efficiency through the series connection of multiple phase-shifted outputs.
2Object-generated harmful factors
If low voltage, low frequency operation is used to reduce cost, THD, EMI, and leakage current, then safety and environmental compliance improve, but power conversion efficiency and energy density decrease
Solution Approach 1:
The patent merges multiple low voltage, low frequency inverter outputs by connecting them in series with appropriate phase shifting. This combination allows the system to maintain the low voltage operation benefits (low cost, low THD, low EMI, low leakage current) while achieving high power conversion efficiency equivalent to high voltage systems, as each inverter operates in its optimal low voltage regime.
3Power
If high voltage components and isolation transformers are used to achieve desired output voltage, then voltage level requirements are met, but cost increases and device complexity increases
Solution Approach 1:
Instead of using a single high voltage inverter with isolation transformer, the patent segments the voltage generation into multiple low voltage inverters connected in series. Each inverter operates at safe low voltage (e.g., 24.2V) eliminating the need for isolation transformers and high voltage components, while the series connection of multiple inverters achieves the required output voltage level through additive voltage summation.
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 LV LF MLPC system achieves cost savings, high efficiency, and compliance with safety standards by generating a 240 Vrms, 60 Hz voltage wave with low THD and EMI, reducing switching losses, and eliminating the need for isolation transformers and high voltage devices, while allowing for module-level control and Maximum Power Point Tracking (MPPT) for PV panels.
Implementation Method 1
Each of the plurality of phase-shifting inverters may be configured to receive at least one of the plurality of low voltage source inputs; and generate at least one square wave output. A semi-sine wave output may be derived from the generated at least one square wave output.
Implementation Method 2
The present disclosure may use low voltage, low cost, high performance components (e.g. MOSFETs, diodes, capacitors, inductors, resistors, etc.) and may drive the power devices (e.g. MOSFETs and diodes) at low frequency (e.g., utility frequency) to generate a desired voltage and current wave
Data Source
AI summary
A low voltage, low frequency multi-level power converter capable of power conversion is disclosed. The power converter may include a low voltage, low frequency circuit that includes a plurality of phase-shifting inverters in series; a plurality of low voltage source inputs, and a plurality of phase-shifting inverters in series. Each of the plurality of phase-shifting inverters may be configured to receive at least one of the plurality of low voltage source inputs; and generate at least one square wave output. A semi-sine wave output may be derived from the generated at least one square wave output.