AC-DC Power Converter with Bidirectional DC Converter
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Solution Overview
Problem
Conventional AC-DC power converters have low power density due to the large volume of capacitors required to meet DC bus voltage requirements, which increases the size and reduces efficiency.
Innovation Solution
The introduction of a bidirectional DC converter that raises the valley value of the DC bus voltage, allowing it to meet input voltage requirements for a longer time interval, thereby reducing the necessary capacitance and volume of capacitors, and improving power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitor with large capacitance and high withstand voltage is used at the output end of the rectifier bridge, then the DC bus voltage requirements are met under low AC input voltage and full-load conditions, but the volume of the converter increases and power density decreases
Solution Approach 1:
The patent divides the voltage boosting function into two stages: the rectifier bridge performs initial rectification, and the bidirectional DC converter performs additional voltage boosting when needed. This segmentation allows the capacitor to operate at lower voltage and capacitance ratings while maintaining DC bus voltage stability through coordinated operation of both stages.
Solution Approach 2:
The bidirectional DC converter dynamically adjusts its operation based on the DC bus voltage level. When the DC bus voltage drops below a threshold, the converter activates to boost the voltage; when the voltage is sufficient, the converter remains inactive. This dynamic control eliminates the need for oversized capacitors designed for worst-case static conditions.
2Adaptability or versatility
If a capacitor with high withstand voltage is used to meet high AC input voltage requirements, then the converter can handle high voltage inputs, but the capacitor volume increases and power density decreases
Solution Approach 1:
The bidirectional DC converter provides dynamic voltage adjustment capability, allowing the system to adapt to both high and low AC input voltages. The converter activates only when the DC bus voltage falls below the required threshold, enabling the use of smaller capacitors with lower withstand voltage ratings while maintaining versatility across the full input voltage range.
3Stress or pressure
If the DC bus voltage valley value is low, then the circuit operates with smaller voltage stress on components, but the time interval for which the DC bus voltage meets input voltage requirements of the DC converter is reduced
Solution Approach 1:
The bidirectional DC converter performs preliminary action by detecting when the DC bus voltage approaches the minimum required level and activates before the voltage drops too low. This proactive voltage boosting ensures the DC bus voltage remains within the acceptable range for the DC converter throughout the AC cycle, extending the compliance time interval while maintaining moderate voltage stress on components.
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
This solution extends the time interval for which the AC input power supply provides power to the DC converter, reducing the volume of capacitors needed and enhancing the overall power density of the converter.
Implementation Method 1
a rectifier circuit, configured to rectify an AC input power supply to generate a DC bus voltage
Implementation Method 2
a bidirectional DC converter, configured to raise a valley value of the DC bus voltage, to increase a time interval for which the DC bus voltage meets input voltage requirements of the DC converter
Data Source
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AI summary
An AC-DC power converter and a conversion method for the AC-DC power converter are provided. A DC bus voltage can meet input voltage requirements of a subsequently connected DC converter by means of a bidirectional DC converter connected to a rectifier circuit, to increase a time interval for which the AC input power supply provides power to the subsequently connected DC converter, and reduce the requirements for capacity and a volume of a first capacitor in the rectifier circuit and capacity and a volume of a second capacitor connected to the second end of the bidirectional DC converter, so that a total volume of the capacitors connected at the subsequent stage of the rectifier bridge can be greatly reduced, to reduce a volume of the power converter, thereby improving the power density of the power converter.