Non-isolated DC/AC Converter with Dynamic Voltage Boosting
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Solution Overview
Problem
Existing non-isolated dc/ac converters face high power loss due to continuous switching and the need for high-capacitance storage capacitors, which increases costs and reduces efficiency.
Innovation Solution
A non-isolated dc/ac converter design incorporating a voltage shift circuit and a voltage boost circuit, along with a feedback module, that adjusts the input voltage to meet output demands, reducing switching loss and eliminating the need for high-capacitance storage capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the first stage dc/dc converter raises the input voltage to a value higher than the peak output voltage to ensure sufficient voltage for all output conditions, then the converter can handle a wide range of output voltages, but the second stage operates under continuously high voltage causing increased power loss
Solution Approach 1:
The patent applies dynamics by making the first stage output voltage adjustable rather than fixed. The converter dynamically adapts the DC bus voltage to match the actual peak output voltage requirement, which varies with AC output voltage and power factor. This dynamic adjustment ensures the second stage always operates at the minimum necessary voltage, reducing power loss while maintaining adaptability to different output conditions.
Solution Approach 2:
The patent changes the voltage parameter of the DC bus dynamically based on operating conditions. By monitoring the AC output voltage and power factor, the system adjusts the DC bus voltage parameter to match actual requirements, rather than maintaining a constantly high voltage. This parameter change approach resolves the contradiction between maintaining voltage adaptability and reducing energy loss.
2Adaptability or versatility
If the first stage dc/dc converter continuously maintains the bus voltage higher than the peak output voltage to ensure sufficient voltage headroom, then the converter can respond to varying output demands, but the switching frequency increases causing higher power loss
Solution Approach 1:
The system dynamically adjusts the switching frequency and voltage conversion ratio based on actual output requirements. When the AC output voltage is high or power factor is low, the DC bus voltage is increased accordingly, but not excessively. This dynamic control reduces unnecessary switching operations while maintaining the ability to respond to output demands, thereby reducing switching losses.
Solution Approach 2:
The patent employs feedback control to monitor the AC output voltage and power factor, then adjusts the first stage converter operation accordingly. This feedback mechanism ensures the DC bus voltage is raised only to the extent necessary for current operating conditions, preventing excessive voltage elevation that would cause increased switching frequency and power loss.
3Stability of the object's composition
If a storage capacitor with high capacitance is used to maintain stable bus voltage under varying conditions, then voltage stability is improved, but the cost increases
Solution Approach 1:
The patent changes the approach from using a large fixed capacitance to using a smaller capacitor combined with active voltage regulation. By dynamically adjusting the DC bus voltage through the first stage converter based on actual load conditions, the system maintains voltage stability without requiring an oversized storage capacitor, thus reducing cost while preserving stability.
Solution Approach 2:
The patent replaces the passive approach of using a large physical capacitor (mechanical/electrical component) with an active control system that uses power electronic switching and control circuitry to maintain voltage stability. This substitution allows voltage stability to be achieved through control actions rather than through the physical properties of a large capacitor, reducing component cost.
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 reduces switching loss, lowers costs, and enhances conversion efficiency by optimizing voltage modulation and capacitor usage.
Implementation Method 1
a voltage boost circuit boosting an output voltage from the dc/dc converting module when the input voltage from the voltage shift circuit is insufficient for the ac output source
Data Source
AI summary
A non-isolated dc/ac converter for converting a dc input source into an ac output source is provided. The converter includes a dc/dc converting module and a dc/ac converting module. The dc/dc converting module includes a voltage shift circuit receiving an input voltage from the dc input source and outputting the input voltage, and a voltage boost circuit boosting an output voltage from the dc/dc converting module when the input voltage from the voltage shift circuit is insufficient for the ac output source. The dc/ac converting module receives the output voltage from the dc/dc converting module and converts the output voltage into the ac output source.