Multilevel Inverter Transformer Merging and DSP Control
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Solution Overview
Problem
Step wave power converters are bulky due to the need for multiple transformers and produce blocky AC waveforms, which are undesirable for modern electronic devices requiring closely regulated power supplies, and existing current control methods like predictive control are resource-intensive and sensitive to parameter inaccuracies.
Innovation Solution
A current-control prediction scheme for multilevel grid-tied inverters using a Digital Signal Processor (DSP) to manage duty ratios and output voltages across multiple bridges, combined with inductive filtering to reduce electromagnetic interference and acoustic noise, allowing for sinusoidal transformer operation and efficient power conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple transformers are used to increase AC output resolution, then waveform quality is improved, but device bulkiness increases
Solution Approach 1:
The patent combines multiple transformer functions into a single integrated transformer by connecting primary windings in series and secondary windings in parallel. This merging approach maintains the ability to generate multi-level AC output waveforms while eliminating the need for multiple separate transformers, thereby reducing device bulkiness while preserving waveform quality.
Solution Approach 2:
The single transformer is designed to perform multiple functions simultaneously: it generates multi-level voltage outputs, provides galvanic isolation, and enables configurable voltage ratios. The transformer structure supports both series and parallel connection modes, making it a universal component that replaces multiple specialized transformers while maintaining system versatility.
2Measurement precision
If predictive control is used to improve current control precision, then current control precision is improved, but computational resource requirements increase
Solution Approach 1:
The predictive control system continuously monitors actual current values and compares them with reference current values, using this feedback to calculate and adjust switching duty ratios in real-time. This closed-loop feedback mechanism ensures precise current control while optimizing computational resource usage by only performing calculations when deviations are detected.
Solution Approach 2:
The system predicts required switching actions in advance based on current error signals and system parameters, calculating optimal duty ratios before the next switching cycle begins. This preliminary calculation approach allows the system to maintain high precision current control while reducing real-time computational burden by preparing control signals ahead of time.
3Object-affected harmful factors
If inductive filtering is added to reduce EMI and noise, then electromagnetic interference is reduced, but device complexity increases
Solution Approach 1:
Inductive filtering components are introduced as intermediary elements between the transformer output and the load. These inductors act as mediators that smooth voltage transitions, reduce high-frequency switching noise, and minimize electromagnetic interference without fundamentally altering the core converter architecture. The filtering is achieved by adding discrete inductive elements rather than redesigning the entire system.
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 reduces the bulkiness of power converters, improves AC waveform quality, and enhances current control precision while minimizing computational resources and noise interference, making it suitable for modern electronic devices.
Implementation Method 1
inductive filtering to reduce electromagnetic interference and acoustic noise
Implementation Method 2
transformers for transforming a DC voltage into a step wave AC output
Data Source
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AI summary
A step wave power converter comprises multiple different bridge circuits configured to convert DC voltage inputs into AC voltage outputs. A controller is configured to estimate an average voltage output from the multiple different bridge circuits for controlling the current output from the multiple different bridge circuits. The number of bridge circuits needed to provide the estimated average output voltage is identified and the identified bridge circuits controlled during a next switching period to generate a combined inverter output voltage that corresponds with the estimated average output voltage. In another embodiment, one or more transformers are associated with the different bridge circuits. Inductors are coupled between the bridge circuits and the primary windings of the associated transformers. The inductors filter the current output from the bridge circuits prior to feeding the current into the transformers.