DAB DC/DC Converter Step-Up-Down Control
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Solution Overview
Problem
Conventional isolated bidirectional DC/DC converters face challenges in maintaining a stable output voltage during step-up/step-down operations, leading to inefficiencies.
Innovation Solution
A power conversion apparatus with a dual active bridge (DAB) DC/DC converter configuration, utilizing a controller to manage switching states and periods between six distinct states, ensuring continuous control of the step-up/step-down ratio by adjusting the periods of specific switching states, thereby stabilizing the output voltage and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a method for switching between step-up chopper and step-down chopper is used to realize high efficiency, then energy conversion efficiency is improved, but output voltage becomes unstable and changes during switching
Solution Approach 1:
The patent applies dynamics by making the switching element configuration changeable over time through six distinct switching states. The controller dynamically adjusts which switching elements are ON or OFF in each state, enabling the system to adapt between step-up and step-down operations while maintaining stable output voltage through controlled transitions between states.
Solution Approach 2:
The patent implements periodic action by cycling through six predefined switching states in sequence. Each state represents a specific configuration of switching elements, and the periodic repetition of these states enables continuous stable operation. The controller manages the periodic transitions between states to maintain both efficiency and voltage stability.
2Productivity
If conventional DC/DC converter switching is used, then high efficiency operation is achieved, but output voltage fluctuates during mode transitions
Solution Approach 1:
The patent segments the power conversion process into six distinct switching states, each with a specific configuration of ON/OFF switching elements. This segmentation allows the controller to manage transitions in a controlled manner, preventing voltage fluctuations by ensuring smooth progression through predefined states rather than abrupt mode changes.
Solution Approach 2:
The controller implements feedback by monitoring the operational state and adjusting the switching element configurations accordingly. The controller determines which of the six states to execute based on system conditions, creating a closed-loop control system that maintains both efficiency and voltage stability through continuous adjustment.
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 suppresses output voltage fluctuations and achieves high efficiency in power conversion by rapidly controlling reactor currents and step-up/step-down ratios, reducing switching losses and maintaining stable operations.
Implementation Method 1
a first energy accumulating/converting unit which is connected to the first connection point and the second connection point and includes one winding wire of a transformer; and a second energy accumulating/converting unit which is connected to the third connection point and the fourth connection point and includes another winding wire of the transformer
Implementation Method 2
at least one of the first energy accumulating/converting unit and the second energy accumulating/converting unit has a reactor which is connected to the winding wires of the transformer in series
Data Source
AI summary
An output voltage is suppressed from changing and high efficiency is realized in a power conversion apparatus capable of performing a step-up/step-down operation. In a power conversion apparatus including a DAB DC/DC converter, when energy transmitted from a primary side and energy accumulated in a reactor at a secondary side are output from the secondary side, of a control signal of a first switching element and a control signal of a fourth switching element which are both in ON states, the first and fourth switching elements being diagonal to each other in a full bridge at the primary side, a period Toff2 in which the control signal of the first switching element is turned off before the control signal of the fourth switching element is turned off is controlled, and thereby a step-up/step-down ratio is continuously changed.