HV Store Voltage Conversion Unit for EV Low-Voltage Charging
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Solution Overview
Problem
Vehicles with electric drive trains experience inefficient charging of low-voltage batteries during stationary and idling phases, leading to premature aging and high electrical losses due to poor efficiency of central DC/DC converters, which results in increased energy and pollutant burdens.
Innovation Solution
A high-efficiency low-voltage tap is integrated within the high-voltage store's housing, utilizing a voltage conversion unit to supply idling and stationary current directly from the high-voltage store, eliminating the need for a central DC/DC converter and reducing power losses, while using a comparator circuit to manage the voltage conversion unit's operation based on hysteresis thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a central DC/DC converter is used to charge the low-voltage battery during stationary and idling phases, then the battery can be recharged, but electrical losses increase and charging efficiency decreases
Solution Approach 1:
The patent extracts the voltage conversion function from the central DC/DC converter and relocates it to a voltage conversion unit integrated within the high-voltage store housing. This eliminates the need for the central DC/DC converter to handle low-voltage battery charging during stationary and idling phases, thereby reducing electrical losses and simplifying the overall system architecture.
Solution Approach 2:
The high-voltage store becomes self-sufficient by integrating the voltage conversion unit within its own housing. The high-voltage store can directly provide power and perform voltage conversion for the low-voltage battery without relying on the central DC/DC converter, enabling autonomous operation during stationary and idling phases.
2Loss of energy
If a central DC/DC converter is used for voltage conversion, then power can be converted between voltage levels, but power losses increase
Solution Approach 1:
The patent merges the voltage conversion unit with the high-voltage store by integrating it within the same housing. This combination creates a unified system where the high-voltage store and voltage conversion unit work together as a single entity, reducing power losses through optimized internal connections and eliminating the need for external DC/DC converter operations.
3Adaptability or versatility
If the voltage conversion unit is permanently connected to the high-voltage battery, then voltage conversion is always available, but the connection cannot be switched off
Solution Approach 1:
The patent introduces a contactor as an intermediary switching element between the high-voltage battery and the voltage conversion unit. The contactor can disconnect the voltage conversion unit from the high-voltage battery when not in use, providing a clean break in the electrical connection. This maintains the permanent availability of the voltage conversion capability while enabling controlled disconnection through the contactor switching mechanism.
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 enables energy-efficient recharging of low-voltage batteries, reduces the size and weight of lead-acid batteries, improves electrical efficiency, and enhances the energy and pollutant balance of the vehicle, while minimizing the risk of battery failure.
Implementation Method 1
electric voltage of the first nominal voltage level can be substantially converted into voltage of the second nominal voltage level by the voltage conversion unit
Implementation Method 2
using a comparator circuit to manage the voltage conversion unit's operation based on hysteresis thresholds
Data Source
AI summary
A vehicle electrical system includes a first partial electrical system having a first energy store of a first nominal voltage level, a second partial electrical system having a second energy store of a second nominal voltage level, and a DC-DC converter between the two partial electrical systems. The first energy store has a housing, which has at least a first tap for the first nominal voltage level, and by which a first DC-DC converter can be electrically supplied. The housing has at least a second tap for the second nominal voltage level, by which the second energy store can be electrically supplied. The housing further includes a voltage conversion unit, by which the voltage of the first nominal voltage level can be converted into voltage of the second nominal voltage level.