Isolated DC Charging Circuit for Fixed-Voltage Vehicle Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle electrical systems face challenges in operating at high voltages without excessive filter capacities, which can lead to dangerous electric shocks due to faulty insulation, and require complex configurations to manage accumulator voltages effectively.
Innovation Solution
A vehicle electrical system with a non-configurable accumulator connected in series without switches, coupled with a galvanically isolating DC-DC converter that isolates the DC charging connection from Cy capacitances, reducing the need for additional switches and allowing for a fixed nominal voltage, and incorporating a switchable connection circuit with direct and charging connection switches to manage energy flow safely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filter capacitors are used in high-voltage vehicle electrical systems, then interference from switched components is diverted, but the risk of electric shock increases due to excessive capacitance
Solution Approach 1:
A DC-DC converter is introduced as an intermediary component between the high-voltage battery and the DC charging port. This converter galvanically isolates the charging port from the battery's filter capacitors, allowing interference diversion to function while preventing dangerous capacitance from reaching the charging port, thus resolving the contradiction between reliability and safety
2Device complexity
If accumulator cells are connected in series without switches, then the nominal voltage remains constant and no additional switches are required, but the inability to reconfigure for different voltages reduces flexibility
Solution Approach 1:
The DC-DC converter acts as a mediator that enables voltage adaptation between the fixed-voltage accumulator and the charging port. Instead of requiring switches to reconfigure the battery, the converter handles voltage transformation, thus maintaining simplicity while gaining flexibility
3Object-affected harmful factors
If the DC charging port is galvanically isolated from Cy capacitances, then the capacitance at the charging port is reduced, but additional switching components are required
Solution Approach 1:
The patent combines the isolation function with the existing DC-DC converter architecture. The converter's switching mechanism serves dual purposes: maintaining galvanic isolation to reduce capacitance and enabling controlled power transfer, thereby achieving capacitance reduction without proportionally 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 configuration minimizes the risk of electric shock by reducing Cy capacitance and eliminating the need for reconfiguring the accumulator, enabling safe and efficient charging and operation of vehicle components while adapting to changing accumulator voltages without reconfiguration.
Implementation Method 1
the galvanic isolation of the DC charging connection from Cy capacitances is achieved in a simple way
Implementation Method 2
filter capacitors (also called Cy capacitors) between the high-voltage potentials of the batteries on the one hand and the ground potential on the other. These serve to divert interference generated
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a vehicle on-board electrical system (FB) equipped with a DC voltage charging connection (DC), a non-configurable battery (AK), an electrically isolating DC voltage converter (GW), and an electrical drive (EA). The battery (AK) is connected to a first side of the DC voltage converter (GW) via a switchable connecting circuit (VS, VS') to which a DC voltage charging connection (DC) is connected. The battery (AK) is connected to the electrical drive (EA) and to a second side of the DC voltage converter (GW) via a drive switch (S3). The connecting circuit (VS, VS') has a direct connecting switch (S1, S1') which switchably connects the battery (AK) to the first side of the DC voltage converter. The DC voltage charging connection (DC) is connected to the direct connecting switch (S1, S1') via a charging connection switch (S2, S2') of the connecting circuit (VS, VS').