Dual-Resistor Discharge System for High-Voltage Capacitor Heat Management
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Solution Overview
Problem
High-voltage power supply systems in motor vehicles face challenges in efficiently discharging energy stores like intermediate circuit capacitors without excessive heat generation, which requires large or complex resistor designs to manage power losses during normal operation.
Innovation Solution
A dual-resistor discharge system where a first discharge resistor is permanently connected in parallel to the energy store, and a second discharge resistor is automatically connected when the voltage falls below a specified threshold, using a switching device to limit power loss and heat generation, allowing for smaller resistor designs and reduced heat dissipation measures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single discharge resistor is permanently connected in parallel to the energy store, then the energy store can be discharged within the specified time span, but the resistor generates excessive heat during normal operation requiring large constructive shapes and additional heat dissipation measures
Solution Approach 1:
The discharge resistor is divided into two separate discharge resistors (first discharge resistor and second discharge resistor) that can be selectively connected. The first discharge resistor with higher resistance is permanently connected for normal operation with minimal power consumption, while the second discharge resistor with lower resistance is temporarily connected only when rapid discharge is needed, avoiding continuous heat generation
Solution Approach 2:
The discharge resistance is made dynamically adjustable by switching between two different resistance values based on operational requirements. During normal operation, the higher resistance is used to minimize power loss, while during emergency discharge, the lower resistance is activated to maximize discharge speed, optimizing both heat management and discharge capability
2Speed
If a discharge resistor with low resistance is permanently connected to achieve rapid discharge, then the discharge time is reduced, but the power loss and heat generation during normal operation becomes excessive
Solution Approach 1:
The discharge path is segmented into two parallel branches with different resistance values. The first branch contains a higher resistance resistor for normal operation with minimal energy loss, while the second branch contains a lower resistance resistor for rapid discharge when needed, allowing optimization of both discharge speed and energy efficiency
Solution Approach 2:
The low-resistance discharge path is activated periodically or on-demand rather than continuously. The switching device connects the second discharge resistor only when rapid discharge is required (such as during emergency shutdown), and disconnects it during normal operation, thereby achieving fast discharge capability without continuous energy loss
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 reduces power loss and heat generation during normal operation while ensuring rapid discharge of energy stores within a specified time, enabling the use of smaller resistor designs and eliminating the need for additional heat dissipation measures, while maintaining efficient discharging capabilities.
Implementation Method 1
a first discharge resistor R1 that is connected parallel to the energy store 2, and a second discharge resistor R2 that is automatically connected parallel to the first discharge resistor R1
Data Source
AI summary
A method and to a device for discharging an energy store, in particular an intermediate circuit capacitor, in a high-voltage power supply system, in particular a DC voltage intermediate circuit in a motor vehicle, a first discharge resistor being connected parallel to the energy store, and a second discharge resistor automatically being connected parallel to the first discharge resistor when a voltage at the energy store falls below a specified threshold value.