DC-DC Converter Ripple Reduction via Transfer Function Control
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Solution Overview
Problem
Existing methods for reducing second-order ripple in DC-DC converters require increased capacitance or circuit complexity, leading to high costs and inefficiencies in power systems with renewable energy sources.
Innovation Solution
A control method and device that adjusts a transfer function based on the output voltage and pulse width modulation amplitude to reduce second-order ripple without increasing capacitance or circuit complexity, using a voltage control device designed for the DC-DC conversion device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the capacitance level of DC-link is increased to absorb second-order virtual work, then the second-order ripple level is reduced, but the cost increases
Solution Approach 1:
The patent changes the control parameters of the DC-DC converter by introducing a second-order ripple compensation current that is inversely proportional to the square of the switching frequency. This parameter adjustment allows the system to reduce second-order ripple effects without increasing the capacitance level, thereby resolving the contradiction between reducing harmful ripple and avoiding increased device complexity
Solution Approach 2:
The patent introduces an intermediary compensation current signal that mediates between the switching frequency variations and the input current ripple. This compensation current acts as a mediator to cancel out the second-order ripple components generated by the DC-DC converter, eliminating the need for increased capacitance while maintaining system performance
2Object-affected harmful factors
If the capacitance level on the input side of DC-DC converter is increased to reduce input voltage ripple, then the input voltage ripple is reduced, but the cost increases
Solution Approach 1:
The patent changes the operating parameters of the DC-DC converter by adjusting the compensation current based on the switching frequency. By modifying the control parameter (compensation current magnitude) rather than the physical parameter (capacitance), the system reduces input voltage ripple without increasing capacitance levels, thus avoiding increased cost and device complexity
3Object-affected harmful factors
If ripple-absorbing circuits are increased to transfer virtual work of DC-link, then the second-order ripple is reduced, but the circuit complexity increases
Solution Approach 1:
The patent extracts the second-order ripple compensation function from separate ripple-absorbing circuits and integrates it into the control logic of the DC-DC converter. By taking out the ripple compensation function and implementing it through control algorithms rather than additional hardware circuits, the system reduces second-order ripple without increasing circuit complexity
Solution Approach 2:
The patent makes the DC-DC converter controller multi-functional by enabling it to perform both power conversion and second-order ripple compensation functions. The controller simultaneously manages the main power transfer and generates the compensation current, eliminating the need for separate ripple-absorbing circuits and reducing overall circuit complexity
4Object-affected harmful factors
If a current loop is increased in DC-DC converter with current command from voltage loop, then the input voltage ripple is reduced, but the device complexity increases
Solution Approach 1:
The patent merges the voltage loop and current loop control functions into a unified control structure. The compensation current generation is integrated within the existing control loops, where the controller simultaneously processes voltage error signals and generates compensation current commands. This merging eliminates the need for separate, independent control loops while maintaining the ripple reduction capability
Data Source
AI summary
A control method for reducing second-order ripple is adapted to reduce second-order ripple on an input side of a DC-DC conversion device, wherein the input side of the DC-DC conversion device is coupled to a preceding voltage supply device, and an output side of the DC-DC conversion device is coupled to a DC-AC transforming device, characterized in that a voltage control device for controlling the preceding voltage supply device is designed according to a transfer function, and the transfer function is adjusted and controlled with an output voltage of the DC-DC conversion device and an amplitude voltage of pulse width modulation to reduce second-order ripple of an input voltage input to the input side of the DC-DC conversion device, thereby dispensing the need to increase circuits or increase capacitance of components and cutting costs.