Intermediate Circuit Discharge Control for Fast Multi-Level Inverter Bleeding
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Solution Overview
Problem
Existing electrical units for vehicles lack an efficient mechanism to rapidly discharge intermediate circuits during faults or shutdowns, with active discharge circuits being non-operational during normal conditions and passive discharge circuits causing significant power loss due to high resistance, resulting in longer discharge times.
Innovation Solution
The integration of a control system that allows the active discharge branch to be activated or deactivated by the passive discharge branch, enabling rapid discharge via a low-resistance resistor and automatic switching, while the passive discharge branch provides continuous voltage for control, allowing for efficient voltage balancing and symmetry across multiple voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passive discharge branch with high resistance is provided, then continuous discharge capability is ensured, but power loss increases and discharge time becomes significantly longer
Solution Approach 1:
The discharge branch is segmented into multiple parallel sub-branches (first sub-branch with voltage limiting valve, second sub-branch with second switching element, third sub-branch with third switching element). This segmentation allows different discharge paths to operate simultaneously or selectively, enabling continuous discharge capability while reducing overall resistance and power loss compared to a single high-resistance passive branch.
Solution Approach 2:
The discharge branch transitions from a static high-resistance passive circuit to a dynamic system where resistance can be adjusted by activating different sub-branches. The control unit can dynamically switch between sub-branches based on operating conditions, allowing the system to optimize between continuous discharge capability and power loss reduction.
2Speed
If an active discharge branch with low resistance is provided, then rapid discharge capability is improved, but the branch cannot operate during normal conditions and requires separate control
Solution Approach 1:
The active discharge branch with low resistance is merged with the passive discharge branch with high resistance into a unified discharge circuit. The control unit integrates control of multiple switching elements (first, second, third switching elements) to coordinate discharge across different sub-branches. This merging allows rapid discharge capability to be achieved while maintaining continuous operation capability through the integrated control system that can activate appropriate sub-branches based on conditions.
Solution Approach 2:
The unified discharge branch serves multiple functions: it provides rapid discharge when low resistance is needed, ensures continuous discharge capability when high resistance is acceptable, and allows selective activation of different sub-branches for various operating conditions. The control unit implements multi-functionality by coordinating multiple switching elements to achieve different discharge modes as needed.
3Adaptability or versatility
If multiple discharge sub-branches are provided in parallel, then discharge flexibility and voltage balancing capability are improved, but device complexity increases
Solution Approach 1:
The discharge branch is divided into three distinct sub-branches connected in parallel, each with its own switching element and discharge characteristics. The first sub-branch includes a voltage limiting valve for overvoltage protection, the second and third sub-branches provide additional discharge paths. This segmentation provides discharge flexibility and voltage balancing capability by allowing selective activation of different sub-branches based on voltage levels and operating conditions.
Solution Approach 2:
The control unit acts as an intermediary that manages the complexity of coordinating multiple parallel sub-branches. It receives voltage level information, determines appropriate discharge actions, and activates the corresponding switching elements. This intermediary control simplifies the overall system by providing a centralized decision-making mechanism that coordinates the multiple discharge paths without requiring complex interconnections between the sub-branches themselves.
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 rapid and efficient discharge of intermediate circuits, reducing power loss and allowing for precise voltage adjustment during charging and operation, ensuring voltage symmetry and asymmetry as needed, thereby enhancing the performance of multi-level converters in vehicles.
Implementation Method 1
the passive discharge branch is electrically connected to the first control terminal. By discharging along the passive discharge branch, either no voltage or an electrical voltage can be applied to the first control terminal
Implementation Method 2
enabling rapid discharge via a low-resistance resistor
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to an intermediate circuit discharge unit (1) for discharging an intermediate circuit, in particular of a multi-level inverter, having a capacitor (4) and a discharge circuit which is connected in parallel, wherein the discharge circuit has an active discharge branch (10) with at least one first discharge element (12) and a passive discharge branch (20) with at least one second discharge element (22). The active discharge branch (10) has a first control connection (15), and the passive discharge branch (20) has a second control connection (25b). The active discharge branch (10) is coupled to the passive discharge branch (20) via the first control connection (15) in such a way that the active discharge branch (10) can be controlled by the passive discharge branch (20), in particular a discharging process via the active discharge branch (10) can be activated or deactivated as required. The invention further relates to an electrical unit, a vehicle and a method.