DC-DC Converter Discharge for High-Voltage Capacitors
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Solution Overview
Problem
Existing electrical systems with intermediate-circuit capacitors in motor vehicles face challenges in rapidly discharging these capacitors after switch-off, especially when dealing with higher voltage traction networks, and must manage dynamic voltage spikes to prevent component damage.
Innovation Solution
A method and device utilizing a DC DC converter to connect and discharge the intermediate-circuit capacitor into a low-voltage onboard power supply network, with controlled output voltage settings to manage discharging and prevent overloading, ensuring the voltage remains within safe limits by setting the output voltage to higher values for defined periods to facilitate safe energy transfer and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the intermediate-circuit capacitor is discharged using a resistor connected in parallel, then the capacitor can be discharged, but the discharging process is slow and does not meet the requirement of dropping voltage below 60 volts within 5 seconds
Solution Approach 1:
The patent introduces a DC-DC converter as an intermediary device between the high-voltage first electrical network (containing the intermediate-circuit capacitor) and the low-voltage second electrical network. The converter actively controls the discharge process by converting electrical energy from the capacitor and transferring it to the second network, enabling rapid voltage reduction while meeting the 5-second requirement, unlike passive resistor discharge.
2Productivity
If the output voltage of the DC DC converter is set to high values to facilitate rapid energy transfer, then discharging speed improves, but electrical and thermal loading spikes occur that can damage components
Solution Approach 1:
The patent employs dynamic voltage control where the output voltage of the DC-DC converter is continuously adjusted based on real-time conditions. The control device monitors the discharge process and adapts the output voltage to optimize energy transfer while preventing harmful spikes, transitioning from static to dynamic operation to balance speed and component protection.
Solution Approach 2:
The patent implements a feedback control mechanism where the control device monitors the discharge process and adjusts the output voltage accordingly. This feedback loop ensures that voltage and current remain within safe limits while maintaining efficient discharge, preventing thermal and electrical overload of components.
3Device complexity
If static considerations are used for discharge control, then the control method is simple, but dynamic voltage spikes from load changes are not properly managed
Solution Approach 1:
The patent transitions from static to dynamic control by continuously monitoring and adjusting the DC-DC converter operation based on real-time electrical conditions. This dynamic approach enables the system to respond to load changes and voltage spikes, providing reliable protection while managing the increased control complexity through automated feedback mechanisms.
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 approach effectively discharges the intermediate-circuit capacitor without causing long-lasting electrical and thermal loading spikes, ensuring the onboard power supply network remains within permissible voltage levels, thereby protecting components and preventing damage.
Implementation Method 1
The first electrical network is discharged by means of the DC DC converter, wherein, at the same time, electrical energy is transferred into the second electrical network
Data Source
AI summary
A method, a device and an electrical system for discharging a first electrical network. The first electrical network comprises in particular an intermediate circuit which comprises in particular an intermediate-circuit capacitor. The first electrical network is connected to a second electrical network by means of a DC-DC converter for this purpose. The first electrical network is discharged by means of the DC-DC converter. At the same time, the DC-DC converter transfers electrical energy into the second electrical network. For discharging, the output voltage of the DC-DC converter is set to a first voltage value, which is larger than the nominal voltage of the second electrical network. For discharging, the output voltage of the DC-DC converter is set to the first voltage value for a predefinable first period of time.