DC-DC Converter System for Electric Vehicle Power Management
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Solution Overview
Problem
Existing electrical power management systems in electric vehicles with multiple energy sources, such as batteries and fuel cells, face inefficiencies due to voltage variations, leading to reduced traction chain power and increased heating, as well as the need for multiple chargers for different battery voltages, resulting in higher costs and complexity.
Innovation Solution
A method for controlling a DC-DC converter system that connects multiple power sources in parallel to a high voltage network, using voltage step-up and step-down converters, with a control algorithm that sets power targets based on the high voltage network's voltage setpoint and source capacities, optimizing power distribution and charging, and incorporating a resonant charger for efficient energy transfer and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a DC/DC converter is used to connect the least powerful power source to the most powerful power source, then voltage adaptation is achieved, but the traction chain is subject to voltage variations from the most powerful source, reducing efficiency and maximum power
Solution Approach 1:
Each power source is equipped with its own DC-DC converter, making each converter a universal interface that can independently regulate voltage from its specific power source to the common high voltage network, eliminating the vulnerability to voltage variations from any single source
Solution Approach 2:
The single DC-DC converter architecture is segmented into multiple independent DC-DC converters, one for each power source. This segmentation isolates voltage variations to individual converters while maintaining stable voltage on the common high voltage network through independent control of each converter
2Power
If the traction chain is dimensioned to provide full power at low voltage, then full power is available at low voltage, but the inverter cost increases due to higher phase current
Solution Approach 1:
The system dynamically changes the voltage parameter on the high voltage network through independent DC-DC converter control. By raising the voltage when full power is needed, the current required is reduced, allowing the inverter to be sized for lower current while still delivering full power when required
3Adaptability or versatility
If multiple batteries of different voltages or chemistry coexist, then flexibility in power sources is increased, but several DC/DC converters are necessary, increasing system complexity
Solution Approach 1:
Each DC-DC converter is designed as a universal interface for its specific power source type, with independent control that adapts to different voltages and chemistries. This universality allows multiple different power sources to coexist without requiring additional conversion stages or increasing overall system complexity
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 solution enhances the efficiency and sustainability of energy transfer, reduces heating in the traction chain, and allows for seamless charging and power distribution across multiple sources, improving the overall performance and reducing costs by optimizing power usage and minimizing the need for multiple chargers.
Implementation Method 1
DC-DC converters being voltage step-ups, one of the DC-DC converters also being voltage step-down
Implementation Method 2
incorporating a resonant charger for efficient energy transfer and storage
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Method for controlling an electrical power supply system for at least one electric traction machine (M) of an electric motor vehicle powered by at least two different power sources (2a, 2b, 2c), the electrical power supply system (1) being connected between the power sources (2a, 2b, 2c) and said at least one electric machine (M), and comprising a DC-DC converter (5a, 5b, 5c) for each power source (2a, 2b, 2c) connected in parallel to the same high-voltage capacitor (6) and to the at least one electric machine (M) associated with an inverter, the DC-DC converters being voltage step-up converters, one of the DC-DC converters also being a voltage step-down converter, the control method comprising the following steps: a voltage setpoint is determined for the vehicle's high-voltage network,The voltage of the vehicle's high-voltage network is measured, and the difference between the setpoint and the measured high-voltage network voltage is determined.