Dynamic DC/DC Converter Control for Fuel Cell Vehicle Power Saving
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Solution Overview
Problem
Existing fuel cell vehicles with DC/DC converters face challenges in electric power saving and miniaturization, as they require continuous-rating considerations that lead to inefficiencies and larger converter sizes.
Innovation Solution
A fuel cell vehicle system that dynamically adjusts the output voltage of the fuel cell based on operational states, using a controller to determine whether the vehicle is in a rated or non-rated state, and accordingly controls the DC/DC converter to step up the voltage only when necessary, thereby saving power and reducing the converter's size by focusing on time-rating rather than continuous-rating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the DC/DC converter continuously steps up the fuel cell output voltage to meet peak traction motor requirements, then the necessary voltage for high-power operation is achieved, but electric power is wasted during low-power operation and the converter size increases
Solution Approach 1:
The patent applies dynamics by making the DC/DC converter's operation state variable rather than fixed. The converter dynamically switches between step-up operation and bypass operation based on real-time vehicle operating conditions (rated vs. non-rated states). This dynamic adaptation allows the system to achieve necessary voltage only when required, eliminating continuous power consumption and resolving the contradiction between maintaining voltage requirements and reducing energy loss.
2Reliability
If the DC/DC converter is designed for continuous-rating to ensure adequate voltage supply, then reliability is improved, but the converter size and weight increase
Solution Approach 1:
The patent uses dynamics to transition from continuous-rating design to time-rating design. By making the converter's operational state dynamic (active only during non-rated states), the system can use smaller, lighter components rated for intermittent operation rather than continuous operation. The bypass diode provides a dynamic alternative path during rated states, maintaining reliability while reducing converter size and weight.
3Power
If the DC/DC converter operates at full capacity continuously, then power delivery capability is maintained, but device complexity and control requirements increase
Solution Approach 1:
The patent applies segmentation by dividing the power delivery path into two separate channels: a DC/DC converter path for non-rated states and a bypass diode path for rated states. This segmentation simplifies the control system, as each component operates in a defined regime rather than requiring complex continuous control. The controller only needs to determine whether the vehicle is in rated or non-rated state, switching between two simple operational modes rather than managing continuous variable control.
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
This approach enables electric power saving and miniaturization of the DC/DC converter by optimizing its operation based on the vehicle's state, reducing unnecessary power consumption and allowing for a smaller, more efficient converter design.
Implementation Method 1
a DC/DC converter for stepping up an output voltage of the fuel cell and supplying the stepped-up voltage to the traction motor
Implementation Method 2
a bypass diode for supplying electric power from the fuel cell to the traction motor in bypassing relation to the DC/DC converter
Data Source
AI summary
A fuel cell vehicle comprises a motor , a fuel cell , a first DC/DC converter, and a first converter control unit . The first DC/DC converter performs a boosting operation when the fuel cell vehicle runs in a non-stationary state, and does not perform the boosting operation during the vehicle runs in a stationary state.