Bi-Directional DC/DC Converter Voltage Control Without PI Tuning
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Solution Overview
Problem
Existing bi-directional DC/DC converters face challenges with voltage tracking errors and dynamic performance due to the need for frequent adjustments of PI parameters and complex circuit dynamics, leading to frequency hopping and inaccuracies in mathematical modeling.
Innovation Solution
A control method for bi-directional DC/DC converters that calculates a theoretical voltage control quantity based on a preset reference voltage and actual voltage values, eliminating the need for PI parameters and generating a switching signal to regulate output voltage, thereby reducing tracking errors and avoiding frequency hopping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If frequency modulation+PI control is used, then the converter achieves good soft switching characteristics and high efficiency, but PI parameters require frequent adjustments and dynamic performance deteriorates
Solution Approach 1:
The system performs self-service through online parameter identification that automatically detects and adapts to changing operating conditions without requiring manual intervention. The controller continuously identifies circuit parameters and adjusts control strategies accordingly, making the system self-adjusting to different working conditions while maintaining optimal efficiency.
Solution Approach 2:
The invention changes control parameters dynamically by switching between different control strategies (frequency modulation, duty cycle modulation, phase shift modulation) based on real-time operating conditions. This allows the system to adapt parameters automatically rather than requiring frequent manual adjustments, resolving the contradiction between maintaining efficiency and avoiding frequent parameter changes.
2Loss of energy
If frequency modulation+PI control is used, then the converter achieves good soft switching characteristics, but frequency hopping occurs when load switches in a large range
Solution Approach 1:
The system implements dynamic control by switching between multiple control strategies based on real-time operating conditions. When soft switching is achievable, frequency modulation is used; when load changes cause frequency hopping, the system transitions to duty cycle or phase shift modulation. This dynamic adaptation maintains both soft switching characteristics and frequency stability across different operating ranges.
Solution Approach 2:
The invention changes the control parameter type dynamically - switching between frequency modulation, duty cycle modulation, and phase shift modulation depending on operating conditions. This allows the system to maintain stable switching frequency while preserving soft switching characteristics when possible, and avoids frequency hopping by using alternative control methods when necessary.
3Adaptability or versatility
If existing control strategy is used, then the converter operates with complex circuit modes, but it is difficult to accurately establish a mathematical model for describing circuit dynamics
Solution Approach 1:
The system performs online parameter identification to automatically determine actual circuit parameters during operation. This self-service approach allows the controller to build an accurate real-time model of the circuit dynamics without requiring a pre-established complex mathematical model, thereby improving measurement precision while maintaining adaptability to different circuit modes.
Solution Approach 2:
The invention performs preliminary parameter identification and model building before control actions are taken. By continuously identifying circuit parameters and updating the mathematical model in advance, the system ensures accurate modeling of circuit dynamics across different operating conditions, resolving the contradiction between model accuracy and circuit complexity.
4Ease of operation
If PI control is used, then voltage control is achieved through frequency adjustment, but voltage tracking error increases in the next control cycle
Solution Approach 1:
The system performs preliminary calculation of the optimal switching frequency or duty cycle based on the voltage error in the current control cycle and predicted voltage behavior in the next cycle. This forward-looking approach allows the controller to pre-adjust control parameters to minimize voltage tracking error in advance, rather than reacting after the error has occurred.
Solution Approach 2:
The invention changes from simple frequency modulation to a more sophisticated control approach that calculates optimal control parameters based on predicted voltage behavior. By dynamically adjusting the control strategy and parameters based on real-time voltage errors and circuit state, the system reduces voltage tracking errors while maintaining operational simplicity.
Data Source
AI summary
A control method for a bi-directional DC/DC converter. A source terminal transmits electric energy to a destination terminal sequentially through a first rectifier module and a second rectifier module of the converter. The method includes obtaining a first voltage value output by the first rectifier module in a current control cycle, obtaining a second voltage value output by the second rectifier module in the current control cycle, calculating a theoretical voltage control quantity of the bi-directional DC/DC converter in the current control cycle based on a preset reference voltage value and the second voltage value, and setting an actual output voltage of the bi-directional DC/DC converter in a next control cycle based on the theoretical voltage control quantity and the first voltage value.