EV On-Board Power Switching for Safe External Load Control
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Solution Overview
Problem
Existing solutions fail to effectively control external loads of electric vehicles to ensure safe operation, particularly while the vehicle is in motion, due to issues such as voltage drops and resets of control units caused by excessive on-board network loads exceeding converter unit capacity.
Innovation Solution
A method and master control unit that determine current information and safety current values to control the power output to external networks by managing the switching unit, disconnecting or adjusting loads as necessary to prevent voltage drops and ensure safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If external loads are connected to the on-board network, then the functionality and versatility of the electric vehicle are improved, but the risk of voltage drops and control unit resets increases when loads exceed converter capacity
Solution Approach 1:
The control unit determines a safety current value in advance before external loads are connected, based on converter unit capacity and current battery charge level. This preliminary assessment prevents overloading by establishing safe current limits beforehand, allowing external loads to be connected without risking voltage drops or control unit resets.
Solution Approach 2:
The control unit continuously monitors current information from the electrical system and dynamically adjusts the safety current value based on real-time converter capacity and battery status. This feedback mechanism ensures that external loads remain within safe operational limits, maintaining system reliability while preserving functionality.
2Power
If the converter unit capacity is increased to handle higher loads, then the power delivery capability is improved, but the device complexity and cost increase
Solution Approach 1:
Instead of increasing converter unit capacity statically, the control unit dynamically determines safety current values based on real-time battery charge levels and converter capacity. This allows the system to adaptively handle varying power demands without requiring a permanently oversized converter, reducing device complexity while maintaining adequate power delivery capability.
Solution Approach 2:
The control unit changes operational parameters (safety current values) based on battery state of charge and converter capacity rather than changing the physical converter capacity itself. This allows the system to optimize power delivery for different operating conditions without increasing hardware complexity.
3Reliability
If the safety current value is set conservatively low to prevent voltage drops, then the reliability is improved, but the available power to external loads is reduced
Solution Approach 1:
The safety current value is dynamically adjusted based on real-time battery charge levels and converter capacity rather than being fixed conservatively. When battery charge is high and converter capacity allows, higher current values are permitted, increasing available power while maintaining reliability. When battery charge is low, the safety current value is reduced to prevent voltage drops.
Solution Approach 2:
The control unit changes the safety current parameter based on operating conditions (battery state of charge, converter capacity) to optimize the balance between reliability and available power. This prevents the need for overly conservative fixed limits that would unnecessarily restrict power availability.
Data Source
AI summary
A method for controlling an electrical system of an electric vehicle. The electrical system comprises a vehicle network and an external network having one or more external loads and connectable to an on-board network. The vehicle network comprises a converter unit adapted for connecting a traction voltage network and an on-board network having a battery unit and one or more internal loads and connected to the converter unit; and a switching unit adapted for controlling power output to the external network by connecting and disconnecting the on-board network and external network. The method comprises the steps of determining at least one current information of the electrical system and at least one safety current value; and controlling the switching unit to control the power output from the on-board network to the external network depending on the at least one current information and the at least one safety current value.