DC/DC Converter Startup PWM Control for Faster EDLC Voltage Supply
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Solution Overview
Problem
The existing DC/DC converters used in conjunction with electric double-layer capacitors (EDLCs) experience delays in output voltage conversion, which is a challenge in achieving immediate voltage supply, especially when multiple EDLCs are connected in parallel or series to meet the high capacity demands of automotive systems, leading to increased cost and size.
Innovation Solution
A switching power supply apparatus is designed with a DC/DC converter and a control unit that outputs a first pulse signal with a gradually decreasing duty from 100% to the first switch, followed by a second pulse signal with duty-controlled output to ensure the output voltage or current of the DC/DC converter reaches a reference value, reducing output delays and preventing premature discharge of the EDLC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DC/DC converter is used to convert voltage from deteriorated EDLCs, then the desired voltage can be obtained, but output delay occurs and response speed deteriorates
Solution Approach 1:
The control unit outputs a first pulse signal with duty gradually decreasing from 100% before the DC/DC converter reaches steady-state operation. This preliminary action allows the converter to build up output voltage rapidly at startup, reducing the output delay while maintaining reliable voltage conversion capability throughout operation
2Quantity of substance
If multiple EDLCs are connected in parallel or series to achieve large capacity, then the required capacity is met, but cost and size increase
Solution Approach 1:
The invention changes the control parameter (pulse duty cycle) dynamically during operation. By gradually decreasing the duty from 100%, the system optimizes the operating point of the DC/DC converter to extract maximum capacity from fewer EDLCs, reducing the total number needed while maintaining required system capacity
3Speed
If pulse duty is maintained at high level for immediate voltage supply, then response speed improves, but EDLC discharge becomes premature
Solution Approach 1:
The control unit performs preliminary action by outputting a first pulse signal with duty gradually decreasing from 100% at startup. This allows the system to achieve immediate voltage supply response while the gradual duty decrease prevents premature EDLC discharge, as the high initial duty is maintained only long enough to establish proper operating conditions
Solution Approach 2:
The invention introduces dynamic control where the pulse duty transitions from a decreasing pattern (first pulse signal) to a regulated pattern (second pulse signal) based on operating conditions. This dynamic adjustment allows the system to optimize between response speed and EDLC discharge timing control throughout different operational phases
Data Source
AI summary
A DC/DC converter has a EFT, and converts a power supply voltage from EDLC by turning on and off the FET. A control unit outputs a first PWM signal whose duty gradually decrease from 100% to the FET when the power supply from the EDLC to the DC/DC convertor is started. Thereafter, the control unit outputs a second PWM signal having a duty controlled so that an output voltage or an output current of the DC/DC converter becomes a reference value to the FET.