DC-DC Converter Control via Digital Current Limiting
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Solution Overview
Problem
Existing DC-DC converter control methods face limitations in responsiveness due to the need for separate sensors and analog control schemes, which hinder efficient maximum output and input current limiting in environment-friendly vehicles.
Innovation Solution
A system and method that utilize a microcomputer to derive limiting current values by dividing power values by voltage values, scaling these to voltage control signals, and generating PWM control signals to manage input and output currents through a bridge converter, eliminating the need for separate sensors and enhancing digital control performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an output current limiting method using a microcomputer is used to limit the maximum output voltage, then the implementation is easy, but the responsiveness is slow due to the need for output current sensors or calculation
Solution Approach 1:
The patent replaces the mechanical/sensor-based current measurement system with a digital calculation system. Instead of using physical output current sensors that slow down the system, the invention calculates the output current limit by dividing the input power limit by the output voltage, converting a mechanical measurement problem into a digital computation problem that executes faster.
Solution Approach 2:
The patent introduces an intermediary calculation method that bridges the gap between input power limiting and output current limiting. By using the relationship P=VI, the system calculates the equivalent output current limit through intermediate computation rather than direct measurement, achieving both accuracy and speed.
2Reliability
If an input current limiting method is used to limit the maximum input, then the maximum output is limited in proportion, but the system requires separate sensors and analog control circuits
Solution Approach 1:
The patent merges the input current limiting function with the existing digital power management system. Instead of adding separate analog control circuits and sensors for current limiting, the invention integrates the limiting logic into the microcomputer's digital control architecture, combining multiple functions into a unified digital system.
Solution Approach 2:
The patent substitutes analog control circuits with digital control implementation. The current limiting function that would traditionally require analog comparators and operational amplifiers is instead implemented through digital calculation and PWM control, eliminating the need for complex analog hardware while maintaining control reliability.
3Speed
If digital control is used to remove separate sensors and improve responsiveness, then the control performance is enhanced, but the system requires precise calculation of limiting current values
Solution Approach 1:
The patent implements a feedback mechanism where the microcomputer continuously monitors the actual output voltage and adjusts the calculated limiting current accordingly. By using real-time voltage feedback in the calculation (Ilimit = Plimit/Vout), the system maintains high precision in the limiting current value despite variations in operating conditions, ensuring both speed and accuracy.
Data Source
AI summary
A system and a method for controlling a DC-DC converter include a microcomputer for deriving an input limiting current value by dividing an input limiting power value by an input voltage value. A conversion circuit scales the input limiting current value to a limiting voltage value. A voltage control circuit derives a control voltage value based on an output voltage value and a reference voltage value and defines the limiting voltage value as a control voltage limiting value. A current control circuit generates a pulse width modulation (PWM) control signal based on the control voltage value.