Bidirectional DC/DC Converter Control Without PI Tuning or Frequency Hopping
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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 control strategies.
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 frequency hopping occurs
Solution Approach 1:
The patent changes the control parameter from switching frequency to duty cycle, eliminating the need for frequent PI parameter adjustments. The control method uses duty cycle modulation instead of frequency modulation, which maintains soft switching characteristics and high efficiency while avoiding the complexity of parameter tuning.
Solution Approach 2:
The patent replaces the mechanical adjustment of PI parameters with an automated control system that directly calculates optimal duty cycle values. This substitution eliminates manual intervention and frequency hopping by using a deterministic control algorithm based on voltage feedback.
2Measurement precision
If PI control with frequency modulation is used, then voltage control is achieved, but frequency hopping occurs when load switches in a large range
Solution Approach 1:
The patent implements dynamic duty cycle adjustment based on real-time voltage feedback. The control method continuously monitors output voltage and dynamically modifies the duty cycle to maintain precise voltage control across varying load conditions without causing frequency hopping.
Solution Approach 2:
The patent employs voltage feedback control where the output voltage is continuously measured and compared with the reference voltage. The duty cycle is adjusted based on the voltage error signal, ensuring precise voltage control and stable switching frequency across different load ranges.
3Power
If existing control strategy with complex circuit modes is used, then power conversion is achieved, but it is difficult to accurately establish mathematical model
Solution Approach 1:
The patent extracts the essential control relationship from complex circuit dynamics by focusing on the primary voltage-duty cycle relationship. The control method simplifies the mathematical model by considering only the critical parameters needed for voltage regulation, eliminating the need for complex circuit mode analysis.
Solution Approach 2:
The patent applies local quality control by focusing on the specific relationship between duty cycle and output voltage at the control point. Rather than modeling the entire complex circuit, the method establishes an accurate local model for voltage control that is sufficient for practical implementation.
4Adaptability or versatility
If PI parameters are adjusted frequently, then adaptation to different working conditions is achieved, but dynamic performance deteriorates
Solution Approach 1:
The patent performs preliminary calculation of the optimal duty cycle value at the beginning of each control cycle based on the current voltage error. This preliminary action eliminates the need for iterative PI parameter adjustment during transient periods, improving dynamic response while maintaining adaptability to different working conditions.
Data Source
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AI summary
The application provides a bi-directional DC/DC converter, a control method and apparatus thereof, and a storage medium. The control method includes: obtaining a first voltage value output by a first rectifier module in a current control cycle; obtaining a second voltage value output by a 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. In this way, a voltage tracking error in the next control cycle may be reduced. Moreover, because PI parameters are not required for control, an output theoretical voltage control quantity is no longer a frequency but a switching signal, which may avoid frequency hopping during switching.