Converter Control Device Phase Switching PID Stability
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Solution Overview
Problem
In power supply systems using fuel cells, existing converter control devices face challenges in maintaining optimal PID control when changing the number of converter phases, leading to inefficiencies and fluctuations in voltage, current, and power due to changes in load and passing power.
Innovation Solution
A converter control device that includes a control unit for PID control, a storage section for predetermining and storing correction functions for the integration term based on the number of drive phases, and a switching mechanism to adjust these functions according to changing power states and thresholds, ensuring appropriate PID control for varying load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the number of converter phases is changed to adapt to varying load conditions, then system efficiency and loss reduction are improved, but PID control stability deteriorates due to fluctuations in voltage, current, and power
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values for the integration term in PID control before actual phase switching occurs. These correction values are determined based on expected phase changes and power levels, allowing the control system to compensate for fluctuations proactively rather than reactively, thereby maintaining stability during phase transitions
Solution Approach 2:
The patent implements feedback by continuously monitoring the actual duty ratio and comparing it with the instruction value, then using this information to adjust the integration term correction in real-time. This closed-loop feedback mechanism ensures that PID control remains stable even when the number of converter phases changes, as the system actively compensates for any deviations
2Adaptability or versatility
If multiple converters are connected in parallel to reduce switching element rating capacity, then device complexity increases, but adaptability to different power states improves
Solution Approach 1:
The patent applies segmentation by dividing the converter system into multiple parallel converter phases that can be independently controlled and switched. This allows the system to operate with different numbers of active phases (single-phase, two-phase, or three-phase) depending on load conditions, providing adaptability while keeping each individual converter module relatively simple in structure
Solution Approach 2:
The patent implements dynamics by enabling the converter system to dynamically change the number of active phases based on real-time power conditions. The control device can switch between one-phase, two-phase, and three-phase operations, allowing the system structure to adapt flexibly to varying load requirements without requiring complete redesign
3Measurement precision
If PID control is used to maintain duty ratio stability, then control precision is improved, but integration term correction becomes necessary when phase changes occur
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the integration term parameter in PID control based on the number of active converter phases and power level. When phase changes occur, the appropriate pre-calculated correction value is applied to the integration term, allowing the PID controller to maintain high precision duty ratio control without requiring complete redesign of the control algorithm
Data Source
AI summary
A converter control device includes a converter device formed by three converter circuits connected together in parallel between a secondary battery as a first power source and a fuel cell as a second power source. A control unit includes: a PID control module for controlling the converter device by PID control and executing a desired voltage conversion; a drive phase quantity changing module for changing the number of drive phases of the converter device in accordance with the passing power of the converter device; and an integration term correction function switching module which switches the PID control integration term correction function when changing the number of drive phases.