Autonomous HV Capacitor Discharge Circuit Using Regulated Gate Current
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Solution Overview
Problem
High voltage electrical systems in vehicles face safety risks due to uncontrolled electrical discharges after conductor breakage, with existing discharge circuits either being costly, inefficient, or requiring high impedance resistors that are difficult to integrate, and active circuits relying on central unit instructions that may not always function.
Innovation Solution
An autonomous discharge circuit that uses power transistors from the high voltage electrical system to dissipate energy, regulating gate current to quickly and safely discharge capacitors, eliminating the need for high impedance resistors and reducing manufacturing costs, while also allowing for automatic operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If passive discharge circuits with high impedance dissipation resistors are used, then automatic discharge is achieved, but the resistor dimensions become large and integration becomes complex
Solution Approach 1:
The patent extracts the dissipation function from a dedicated high-impedance resistor and transfers it to the power transistor Q1, which is already present in the circuit for switching operations. This eliminates the need for a separate large-volume resistor while maintaining automatic discharge capability through the transistor's controlled conduction.
Solution Approach 2:
The power transistor Q1 is made multi-functional by using it both for its primary switching function and for energy dissipation during discharge. By configuring the transistor to conduct in a controlled manner during discharge, it serves dual purposes: power switching and energy dissipation, thereby eliminating the need for dedicated discharge resistors.
2Extent of automation
If passive discharge circuits with high impedance dissipation resistors are used, then automatic discharge is achieved, but the manufacturing cost increases
Solution Approach 1:
The patent makes the power transistor Q1 multi-functional, using it for both switching operations and energy dissipation. This eliminates the need for additional expensive high-impedance resistors, thereby reducing manufacturing costs while maintaining automatic discharge functionality.
Solution Approach 2:
The dissipation function is extracted from a separate expensive resistor component and transferred to the existing power transistor, eliminating the need to purchase and install additional high-cost high-impedance resistors.
3Extent of automation
If passive discharge circuits with high impedance dissipation resistors are used, then automatic discharge is achieved, but the discharge time becomes excessively long
Solution Approach 1:
The patent applies dynamic control to the discharge process by using the power transistor Q1 with regulated gate current, allowing the discharge resistance to be dynamically adjusted. This enables faster discharge times compared to fixed high-impedance resistors, while still maintaining automatic operation through the control unit's regulation of the transistor's conduction state.
4Loss of time
If active discharge circuits are used, then discharge time is reduced, but the circuit becomes inoperative if no instruction is received
Solution Approach 1:
The patent implements a hybrid system where the control unit provides intelligent activation (reducing unnecessary discharge operations) while the automatic sensing and discharge mechanism ensures the circuit operates autonomously when needed. The system serves itself by detecting high-voltage conditions and initiating discharge without requiring manual intervention, combining the benefits of both active and passive approaches.
5Device complexity
If power transistors are used for energy dissipation, then resistor integration is simplified, but the power transistor may be damaged by excessive power
Solution Approach 1:
The patent implements feedback control through the control unit that monitors the discharge process and regulates the gate current to the power transistor Q1. This feedback mechanism ensures the transistor dissipates power within safe limits during discharge, preventing damage while maintaining the simplified integration benefits of using the existing transistor.
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 solution enables rapid and safe discharge of electrical energy storage devices, improving user safety by reducing discharge time and eliminating the need for bulky resistors, while being cost-effective and autonomously operational.
Implementation Method 1
the first power transistor Q1 dissipates a power less than or equal to 5W
Data Source
Figure 1~3
AI summary
The invention relates to a circuit (100) for discharging a high-voltage electrical system comprising at least one power transistor (Q1) and an electrical energy storage device including at least one capacitor (C3), the discharge circuit (100) comprising:– a control branch (120) for configuring the power transistor (Q1) in a conduction mode in order to discharge the capacitor (C3);– a regulating branch (130) designed to control a gate current (iG) flowing into the control branch (120) of the power transistor (Q1), the regulating branch (130) being designed to command the gate current (iG) in such a way that each power transistor (Q1) dissipates a power less than or equal to 5 W during a discharge period less than or equal to 5 seconds enabling discharging of the capacitor (C3). The invention also relates to a control unit of a power electric machine comprising such a discharge circuit (100) as well as a method for discharging a device for storing electrical energy (400).