DC/DC Converter Synchronized Voltage Control
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Solution Overview
Problem
Conventional DC/DC converters face delays in charge/discharge capacitor voltage following target changes due to differing calculation speeds between controllers, leading to potentially high voltage applied to switching elements, increasing costs due to the need for high-withstand-voltage components.
Innovation Solution
A DC/DC converter design with a low-voltage-side and high-voltage-side smoothing capacitor configuration, where semiconductor circuits and a control device calculate and control switching operations to synchronize output and charge/discharge capacitor voltages, allowing for reduced switching element withstand voltage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DC/DC converter control is used with separate controllers for output voltage and charge/discharge capacitor voltage, then voltage control is achieved, but calculation speed differences cause delayed response in charge/discharge capacitor voltage following target changes
Solution Approach 1:
The patent combines the control functions for output voltage and charge/discharge capacitor voltage into a single control device that calculates both operation values simultaneously. This unified control approach eliminates the time delay caused by separate controllers processing at different speeds, as both voltage controls are generated from the same calculation cycle.
Solution Approach 2:
The control device performs multiple functions by calculating both the first operation value for output voltage control and the second operation value for charge/discharge capacitor voltage control within the same control cycle. This multi-functional approach ensures synchronized response times for both voltage parameters without requiring separate dedicated controllers.
2Reliability
If high-withstand-voltage switching elements are selected to prevent overvoltage breakdown during transient periods, then switching element reliability is improved, but manufacturing cost increases
Solution Approach 1:
The unified control device performs preliminary calculations of both operation values before switching operations occur, ensuring that voltage transitions are properly managed in advance. This prevents transient overvoltage conditions that would require expensive high-withstand-voltage switching elements, allowing the use of lower-cost components while maintaining reliability.
Solution Approach 2:
The control device uses feedback from actual voltage measurements to adjust operation values dynamically, preventing overvoltage breakdown conditions. This feedback mechanism ensures switching elements operate within safe voltage limits, eliminating the need to select switching elements with excessive withstand voltage ratings and reducing manufacturing costs.
Data Source
AI summary
In this DC/DC converter, a first controller calculates a first operation value on the basis of a difference between output voltage Vout and a first calculated value calculated on the basis of a detection value of voltage of the charge/discharge capacitor. A second controller calculates a second operation value on the basis of a difference between a charge/discharge capacitor voltage target value Vcf* and charge/discharge capacitor voltage Vcf. In control blocks, addition and subtraction of the first and second operation values are performed, and the conduction rates for switching elements are controlled, to control the output voltage and a charge/discharge capacitor voltage, thereby preventing application of overvoltage to the switching elements.