Current Resonant DC/DC Converter Control for Wide Output Voltage
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Solution Overview
Problem
Existing current resonant DC/DC converters face challenges in achieving a wide range of output voltage without adding elements or circuits and complicating software configurations, particularly in LLC and CLLC converters used for electric vehicle charging and bidirectional power systems, due to limitations in frequency modulation control, phase shift control, and the need for additional circuits for step-up operations.
Innovation Solution
A single-phase and three-phase current resonant DC/DC converter design that utilizes frequency modulation control with integrated output suppression and increase conversion controls, allowing for a wide range of output voltage adjustments without additional components or complex software configurations, by using primary and secondary-side switching elements and resonant circuits with controlled frequency and phase shift amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If frequency modulation control is used to reduce output voltage, then output voltage can be controlled, but driving frequency must be increased which causes loss increase and cannot reduce output to zero
Solution Approach 1:
The patent applies dynamics by making the control method adaptable to different operating conditions. The control unit dynamically switches between frequency modulation control and output suppression conversion control based on the required output voltage level, allowing the system to optimize performance across the full output range without being constrained by a single control method's limitations.
Solution Approach 2:
The patent changes the control parameter from purely frequency modulation to output suppression conversion control when reducing output voltage. Instead of continuously increasing driving frequency, the system uses output suppression conversion control that calculates a suppression amount based on the difference between driving frequency and first frequency, enabling output reduction to zero without excessive frequency increase and associated losses.
2Power
If intermittent control is performed to reduce output, then output voltage range is extended, but output current ripple increases
Solution Approach 1:
The patent implements feedback by having the control unit continuously monitor the driving frequency and calculate the suppression amount based on the difference between driving frequency and first frequency. This feedback mechanism allows the system to adjust the output suppression level dynamically, maintaining stable output current with minimal ripple while achieving the desired output voltage range extension.
3Power
If phase shift control is switched with frequency modulation control to support wide output voltage range, then output voltage range is extended, but control and software configuration becomes complicated
Solution Approach 1:
The patent applies universality by designing the output suppression conversion control to work across the entire output voltage range that previously required switching between multiple control modes. The control unit universally applies the suppression amount calculation based on frequency difference, eliminating the need for separate frequency modulation control and phase shift control configurations while maintaining wide output voltage range capability.
4Adaptability or versatility
If bidirectional step-up/down converter is combined with bidirectional CLLC converter to enable bidirectional operation, then bidirectional operation is achieved, but efficiency decreases and number of components increases
Solution Approach 1:
The patent merges the step-up/down functionality directly into the CLLC resonant converter by implementing output suppression conversion control. This integration eliminates the need for a separate bidirectional step-up/down converter, reducing the number of components while maintaining bidirectional operation capability. The control unit handles both step-up and step-down operations through the same resonant circuit and control mechanism.
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
Enables efficient handling of a wide range of output voltages without increasing complexity or components, maintaining high efficiency and reducing software complexity, suitable for applications like electric vehicle charging and bidirectional power systems.
Implementation Method 1
a primary-side resonant circuit provided between the primary-side leg and the transformer circuit, including a resonant coil and a resonant capacitor
Implementation Method 2
a transformer circuit
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A single-phase current resonant DC/DC converter 1 including a main circuit unit 10 including a transformer circuit Tr, a primary-side switching circuit 11, a primary-side resonant circuit 12, and a secondary-side rectifier circuit 13, and a control unit 20, in which the control unit 20 performs frequency modulation control, output suppression conversion control of reducing output, and output increase conversion control of increasing output, the output suppression conversion control is performed on the basis of a first control amount calculated using a difference between a first frequency and a driving frequency, and the output increase conversion control is performed on the basis of a second control amount calculated using a difference between a second frequency and the driving frequency.