HV-LV Battery System DC/DC Converter Optocoupler Control
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Solution Overview
Problem
Existing battery systems for electric vehicles face challenges in efficiently managing power distribution between high voltage (HV) and low voltage (LV) subsystems, leading to electromagnetic interference (EMI) and increased costs due to the need for additional shielding and space requirements in galvanically isolated DC/DC converters.
Innovation Solution
A battery system with a HV battery subsystem and a LV battery subsystem connected via a DC/DC converter, utilizing a switch controlled by a threshold signal generated in the LV subsystem to manage power distribution, reducing EMI by using an optocoupler for signal transmission and incorporating a buffer capacitor for voltage stabilization, thereby providing a redundant power supply without the need for additional shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If galvanically isolated DC/DC converters are used to manage power distribution between HV and LV subsystems, then power management reliability is improved, but electromagnetic interference increases and additional shielding is required
Solution Approach 1:
The patent introduces an optocoupler as an intermediary component to transmit control signals between the HV and LV subsystems. The optocoupler converts electrical signals to optical signals and back, providing galvanic isolation while controlling the DC/DC converter, thereby reducing electromagnetic interference without compromising power management reliability
Solution Approach 2:
The patent replaces direct electrical connections with optical signal transmission using an optocoupler. This substitution eliminates the need for additional shielding by converting the signal transmission medium from electrical to optical, thus reducing electromagnetic interference while maintaining system reliability
2Object-affected harmful factors
If additional shielding is added to reduce electromagnetic interference in DC/DC converters, then EMI is reduced, but costs and space requirements increase
Solution Approach 1:
The optocoupler serves as a mediator that transmits control signals optically between HV and LV subsystems, eliminating the need for additional shielding around the DC/DC converter. This reduces both electromagnetic interference and the space required for shielding components
Solution Approach 2:
The patent extracts the signal transmission function from the electrical domain to the optical domain using an optocoupler. This extraction removes the source of electromagnetic interference from the DC/DC converter circuit, eliminating the need for additional shielding and reducing overall system space requirements
3Productivity
If a switch is controlled by threshold signals to manage power distribution, then power management efficiency is improved, but system complexity increases
Solution Approach 1:
The patent implements a self-service control mechanism where the LV subsystem automatically monitors its own voltage levels and generates threshold signals to control the switch. This autonomous voltage monitoring and control reduces the need for complex external control systems while improving power management efficiency
Solution Approach 2:
The patent employs feedback control where the LV subsystem monitors voltage levels and sends threshold signals back to the HV subsystem to control the switch state. This feedback mechanism enables efficient power management by automatically adjusting power distribution based on actual voltage conditions without requiring complex centralized 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
The solution ensures reliable power supply to both HV and LV loads, reduces electromagnetic interference, and minimizes costs and space requirements by eliminating the need for additional shielding, while maintaining system redundancy and safety.
Implementation Method 1
The threshold signal may be transmitted via an optocoupler from the LV battery subsystem to the HV battery subsystem
Implementation Method 2
a DC/DC converter with a primary coil in the HV battery subsystem and a secondary coil in the LV battery subsystem
Implementation Method 3
The LV battery subsystem may include a buffer capacitor that is interconnected between the supply node and ground
Data Source
AI summary
A battery system for an electric vehicle, including: a high voltage (HV) battery subsystem including a battery cell stack with battery cells electrically connected between stack nodes; a low voltage (LV) battery subsystem including a LV battery and a supply node connectFed to the LV battery; a DC/DC converter with a primary coil in the HV battery subsystem and a secondary coil in the LV battery subsystem, wherein the primary coil is connected to one of the stack nodes via a switch. A threshold signal indicative of a voltage at the supply node may be generated in the LV battery subsystem and may be transmitted to the HV battery system. A state of the switch may be controlled based on the threshold signal.