EV Power Supply Switching Between Parallel and Series Drive Modes
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Solution Overview
Problem
The existing power supply systems for electric vehicles that include a fuel cell and a secondary battery face challenges in achieving high drive power output while maintaining low manufacturing costs and weight, as the inclusion of a voltage control unit in either the fuel cell or the secondary battery leads to inefficiencies and increased costs due to energy losses and insufficient motor voltage.
Innovation Solution
A power supply system that connects a fuel cell directly to the motor unit and a secondary battery via a voltage control unit, with a switch that can switch between parallel and series configurations to optimize voltage supply based on required output, thereby eliminating the need for a voltage control unit on the fuel cell and improving energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a voltage control unit is provided in each of the fuel cell and the secondary battery, then the output power from each can be boosted and large drive output can be obtained, but manufacturing cost increases and weight increases
Solution Approach 1:
The patent merges the voltage control functionality into a single centralized unit that manages both the fuel cell and secondary battery, rather than providing separate voltage control units for each power supply. This consolidation reduces the total number of control units needed, thereby lowering manufacturing cost and weight while still enabling both power sources to contribute to the drive output.
Solution Approach 2:
The single voltage control unit is designed to handle multiple functions: it controls voltage for both the fuel cell and secondary battery, manages power distribution between the two power supplies, and ensures proper voltage matching for the motor. This multi-functional design eliminates the need for separate dedicated control units for each power source.
2Ease of manufacture
If a voltage control unit is provided in one of the fuel cell and the secondary battery, then manufacturing cost and weight are reduced, but the voltage of drive power supplied to the driving motor becomes insufficient and it is difficult to obtain large motive power
Solution Approach 1:
The patent implements dynamic switching between parallel and series configurations of the fuel cell and secondary battery through a switch unit. This dynamic reconfiguration allows the system to adapt voltage and power output levels based on driving conditions, ensuring sufficient voltage for the motor while maintaining cost-effectiveness through a single voltage control unit.
Solution Approach 2:
The system changes the electrical configuration parameters by switching between parallel and series connections. In parallel configuration, voltages are matched and combined for sustained operation; in series configuration, voltages are added to provide high-voltage bursts for acceleration or high-power demands, thereby achieving large motive power without requiring voltage control units on both power supplies.
3Power
If the voltage control unit is provided only in the fuel cell, then the output voltage from the fuel cell is always boosted, but the energy efficiency of the electric vehicle is reduced and manufacturing cost is increased
Solution Approach 1:
Instead of continuously boosting the fuel cell voltage through a voltage control unit, the patent uses periodic switching between parallel and series configurations. The switch unit alternates between connecting the fuel cell in parallel with the secondary battery (for normal operation) and in series (for voltage-boosting scenarios), thereby providing voltage enhancement only when necessary and improving overall energy efficiency.
Solution Approach 2:
The patent extracts the voltage boosting function from a continuous operation mode and implements it only when needed through the series configuration. By taking out the voltage control requirement from the fuel cell's always-on operation and providing it selectively through configuration switching, the system reduces energy losses associated with continuous voltage regulation.
4Ease of manufacture
If the voltage control unit is provided only in the secondary battery, then the voltage of drive power supplied to the driving motor is the output voltage of the fuel cell, but the voltage of the driving motor is insufficient and it is difficult to obtain a large output
Solution Approach 1:
The patent implements dynamic switching between parallel and series configurations to address the voltage insufficiency issue. When high voltage is needed for large motor output, the system switches to series configuration, dynamically changing the electrical topology to provide the necessary voltage boost without requiring a voltage control unit on the fuel cell.
Solution Approach 2:
The system changes the electrical configuration parameter from parallel to series connection to alter the output voltage characteristic. This parameter change enables the fuel cell's output voltage to be doubled when connected in series with the secondary battery, providing sufficient voltage for large motor output while maintaining cost-effectiveness through a single voltage control unit on the secondary battery.
Data Source
AI summary
A power supply system connected to a motor unit of an electric vehicle, the power supply system includes: a fuel cell; a secondary battery; a voltage control unit; and a switch. The fuel cell is directly connected to the motor unit, the secondary battery is connected to the motor unit via the voltage control unit, and the switch is configured to switch between a first state in which the secondary battery and the voltage control unit are connected in parallel with the fuel cell and a second state in which the secondary battery and the voltage control unit are connected in series with the fuel cell.