Power Conversion Device with DC-DC Converter for Stable AC Output
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Solution Overview
Problem
The existing power conversion devices struggle to maintain stable output voltage when the State Of Charge (SOC) of a DC power source varies, leading to unstable voltage supply.
Innovation Solution
A power conversion device comprising a voltage converter connected to a DC power source, a voltage controller to regulate the output voltage, and an inverter circuit to convert the voltage into AC, utilizing a dual active bridge circuit and H-bridge circuit configuration to ensure stable output voltage across varying input voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a direct connection between DC power source and inverter is used, then device complexity is reduced, but output voltage stability deteriorates when DC voltage varies
Solution Approach 1:
A DC-DC converter is introduced as an intermediary component between the DC power source and the inverter. This converter includes a transformer with primary and secondary windings, and control circuits that regulate the converter's operation based on detected DC voltage levels, thereby stabilizing the voltage supplied to the inverter despite variations in the DC power source voltage.
Solution Approach 2:
The system incorporates feedback mechanisms where detection circuits monitor the DC voltage from the power source, and control circuits adjust the DC-DC converter's operation accordingly. The control circuits receive feedback signals about the voltage level and modify the converter's duty cycle or switching characteristics to maintain stable output voltage to the inverter.
2Volume of moving object
If DC voltage is directly supplied to inverter, then device size is reduced, but voltage range adaptability deteriorates
Solution Approach 1:
The DC-DC converter enables parameter changes in voltage level adaptation. By adjusting the converter's switching frequency, duty cycle, or transformer turns ratio, the system can adapt to a wide range of input DC voltages from different power sources (such as batteries with varying SOC levels) and convert them to a stable voltage suitable for the inverter, thereby extending voltage range adaptability.
3Stability of the object's composition
If voltage regulation is added to maintain stable output, then output voltage stability is improved, but device complexity increases
Solution Approach 1:
The DC-DC converter is designed with multi-functionality, serving both as a voltage regulation device and as an interface between different voltage levels. The control circuits perform multiple functions including voltage detection, regulation control, and adaptation to different input voltage conditions, thereby achieving voltage stability without proportionally increasing overall system complexity.
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 achieves stable AC voltage output even with fluctuating DC power source voltages, enabling stable operation of AC motors and extending the voltage range, while also reducing device size and improving efficiency.
Implementation Method 1
a voltage converter connected to a DC power source to convert the output voltage of the DC power source
Implementation Method 2
an inverter circuit provided on the output side of the voltage converter to convert the voltage output from the voltage converter into an AC voltage
Data Source
Figure 1
Figure 2
Figure 3(a)~3(e)
AI summary
There is provided a power conversion device including a plurality of Direct Current (DC) power sources (VB) that converts an output voltage of each of the DC power sources into an Alternating Current (AC) voltage, and outputs the converted AC voltage in series connection, and the device includes: a DC/DC converter (21) connected to each of the DC power sources (VB) to convert the output voltage of the DC power sources; a control device (31) that controls an output voltage of the each DC/DC converter (21); and an H-bridge circuit (22) provided on the output side of the DC/DC converter (21) to convert the voltage output from the DC/DC converter (21) into an AC voltage.