DC-DC Converter and Inverter Precharge for Inrush Current Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Battery electric vehicles (BEVs) face long charging times and potential component damage due to high in-rush currents during startup and shutdown, especially with higher voltage systems.
Innovation Solution
A power control system with a DC-DC converter and power inverter module, controlled by a controller, that manages capacitor pre-charging and shutdown to prevent component damage, using a bidirectional bypass switch and voltage ramping techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher voltage battery systems are used to enable faster charging, then charging speed is improved, but risk of component damage during startup and shutdown increases
Solution Approach 1:
The system performs preliminary pre-charging of capacitors C1 and C2 before main power connection during startup, and preliminary discharge before shutdown. This preliminary action prevents harmful in-rush currents and voltage spikes that could damage components, while enabling the use of higher voltage systems for faster charging.
Solution Approach 2:
The patent introduces precharge resistors RPC1 and RPC2 as intermediary elements between the battery and capacitors during startup, and between capacitors and ground during shutdown. These intermediaries gradually charge/discharge capacitors, preventing direct high-voltage connections that could cause component damage while maintaining fast charging capability.
2Ease of operation
If conventional startup and shutdown procedures are used, then system operation is simple, but high in-rush currents can damage power control system components
Solution Approach 1:
The controller executes preliminary pre-charging sequences before main power connection and preliminary discharge before shutdown. This maintains operational simplicity from the user perspective while internally preventing harmful current spikes through controlled voltage transitions.
Solution Approach 2:
The system dynamically adjusts charging currents through multiple stages: initial pre-charging through resistors, then main charging when voltage thresholds are met. During shutdown, it dynamically discharges capacitors through controlled resistance. This dynamic control prevents in-rush currents while maintaining ease of operation.
3Loss of time
If capacitors are charged directly without pre-charging, then startup time is reduced, but voltage spikes can damage power switches and other components
Solution Approach 1:
The system performs preliminary pre-charging of capacitors C1 and C2 before main power connection. This brief preliminary action prevents voltage spikes that could damage power switches, while the overall startup time remains minimal compared to the protection provided.
Solution Approach 2:
The precharge resistors RPC1 and RPC2 provide beforehand cushioning by limiting in-rush current during capacitor charging. This cushioning effect prevents voltage spikes and current surges that could damage sensitive power control components, enabling safe operation of higher voltage fast-charging systems.
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 system reduces charging time and prevents component damage by controlled voltage transitions, ensuring safe and efficient operation of the power control system.
Implementation Method 1
A DC-DC converter is connected to the energy storage system and including a first capacitor, a first plurality of power switches and an inductor
Implementation Method 2
A power control system for a propulsion system of a vehicle includes an energy storage system including a precharge circuit and one or more battery packs
Implementation Method 3
the controller is configured to, after pre-charging the first capacitor of the DC-DC converter, control an output voltage of the DC-DC converter to ramp up voltage across the second capacitor of the power inverter module
Data Source
AI summary
A power control system for a propulsion system of a vehicle includes an energy storage system including a precharge circuit and one or more battery packs. A DC-DC converter is connected to the energy storage system and including a first capacitor, a first plurality of power switches and an inductor. A power inverter module is connected to the DC-DC converter and including a second capacitor and a second plurality of power switches. A controller is configured to pre-charge the first capacitor of the DC-DC converter and the second capacitor of the power inverter module and control operating modes of the DC-DC converter and the power inverter module.