DC/DC Converter Duty Ratio Correction via Reactor Current Feedback
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Solution Overview
Problem
Existing voltage conversion systems in vehicles, particularly those involving fuel cells and inverters, face challenges in maintaining precise output voltage due to varying fuel cell and secondary battery voltages, leading to insufficient correction of the duty ratio for optimal power management.
Innovation Solution
A voltage conversion device with a control unit that includes detection and correction means to adjust the duty ratio of a switching device, using a reactor and switching devices to manage current flow between a power supply node connected to an inverter and an electric storage device, with proportional-plus-integral-plus-derivative control to ensure precise voltage conversion and stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If proportional-plus-integral control is used to correct the duty ratio based on inverter output power, then voltage stability is improved, but manufacturing precision of output voltage deteriorates due to insufficient correction
Solution Approach 1:
The patent introduces feedback control by detecting the current through the reactor and using this information to correct the duty ratio. The control unit continuously monitors the reactor current and adjusts the switching device's duty ratio based on the detected current values, creating a closed-loop feedback system that improves both voltage stability and precision.
Solution Approach 2:
The patent replaces the conventional proportional-plus-integral control mechanism with an electrical measurement and correction system. Instead of relying solely on power-based correction, the system uses current detection through the reactor and substitutes the correction approach with electrical parameter measurement and real-time duty ratio adjustment.
2Adaptability or versatility
If the voltage converter operates with varying fuel cell and secondary battery voltages, then adaptability to vehicle conditions is improved, but output voltage precision deteriorates
Solution Approach 1:
The patent implements dynamic control by continuously adjusting the duty ratio based on real-time reactor current detection. The control unit modifies the switching device's operation dynamically in response to changing vehicle conditions, fuel cell voltage variations, and battery voltage fluctuations, maintaining precision despite adaptability requirements.
Solution Approach 2:
The patent changes the control parameter from solely power-based correction to current-based correction. By detecting the reactor current and using this parameter for duty ratio correction, the system adapts to varying voltage conditions while maintaining precise output voltage control through parameter-driven adjustment.
3Device complexity
If the duty ratio correction is based on inverter output power alone, then device complexity is reduced, but measurement precision of required correction amount deteriorates
Solution Approach 1:
The patent introduces the reactor current as an intermediary measurement parameter. Instead of directly measuring or calculating the required correction amount from inverter power alone, the system uses the reactor current as an intermediate indicator that provides more precise information about the actual power flow and conversion state, enabling more accurate duty ratio correction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides improved precision in output voltage and enables early convergence to a target value, even with varying reactor currents, ensuring stable power delivery in vehicles.
Implementation Method 1
a voltage converter including: a reactor; a first switching device operative in response to a first activation signal to couple one end of the reactor with a first power supply node
Data Source
AI summary
A DC/DC converter includes a reactor, IGBT devices, a dead time generation unit, and a DC-CPU. The dead time generation unit operates in response to a reference signal for a duty ratio, to output first and second activation signals provided with an inactive period corresponding to a dead time preventing both of the IGBT devices from conducting. The DC-CPU corrects a tentative duty ratio calculated as based on a voltage control value, in accordance with a value of a current flowing through the reactor, to output the reference signal. Preferably the DC-CPU associates the value of the current of the reactor with three states and when the value approaches a value at which a state transitions to a different state, the DC-CPU gradually switches a correction value.