Active Discharge Circuit With Self-Powered Capacitor Discharge
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Solution Overview
Problem
Existing active discharge systems for electric or hybrid motor vehicles are susceptible to power failures, especially after a road accident, leading to incomplete discharge of capacitance and increased safety risks due to high power dissipation and dependence on external power sources.
Innovation Solution
An active discharge system that utilizes control means powered by the accumulated electric charge, allowing for activation independent of external power sources, and includes resistive and switch means to modulate the discharge transient, ensuring safe and efficient discharge within safety time limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a discharge resistor with low resistance value is used to achieve fast discharge time, then discharge time is reduced, but power dissipation becomes unacceptable
Solution Approach 1:
The patent applies dynamics by making the discharge resistor's resistance value variable rather than fixed. The resistor transitions from a high resistance state during normal operation (minimizing power dissipation) to a low resistance state during discharge (achieving fast discharge time). This dynamic adjustment resolves the contradiction between fast discharge and low power dissipation.
Solution Approach 2:
The patent changes the resistance parameter of the discharge resistor over time and operating conditions. By controlling the resistance value to be high during normal operation and low during discharge events, the system achieves both low power dissipation and fast discharge time, directly addressing the technical contradiction.
2Ease of operation
If the active discharge system is powered by a low voltage power source, then the system can operate during normal conditions, but the system fails when the low voltage power source fails after a road accident
Solution Approach 1:
The patent implements self-service by enabling the discharge system to power itself during discharge events. The equivalent capacitance that needs to be discharged provides the power for the control means and switch means through a self-powered control circuit, eliminating dependence on external power sources and ensuring reliability even when the low voltage power source fails.
Solution Approach 2:
The patent prepares for power source failure by designing a dual-power architecture where the system can switch from normal low voltage power to self-powered operation using the equivalent capacitance. This beforehand preparation ensures the discharge function remains available in emergency conditions.
3Speed
If the discharge transient is characterized by fast discharge time and high power dissipation at the beginning, then initial discharge is rapid, but the discharge time becomes particularly slow and power dissipation particularly low at the end, failing to discharge total charge within safety time
Solution Approach 1:
The patent applies dynamics by continuously adjusting the discharge resistor's resistance value during the discharge transient. The resistance is kept low throughout the discharge process to maintain high discharge speed, preventing the transient from becoming slow at the end. This dynamic control ensures the total charge is discharged within the safety time limit.
Solution Approach 2:
The patent uses feedback from the control means to monitor the discharge process and adjust the discharge resistor's resistance accordingly. This feedback control ensures the discharge transient maintains appropriate speed throughout, preventing excessive slowing at the end and ensuring complete discharge within safety requirements.
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 ensures complete and safe discharge of capacitance within safety time limits, reducing power dissipation and operational risks, and is independent of external power sources, enhancing vehicle safety.
Implementation Method 1
use a discharge resistor connected in parallel to the equivalent capacitance in order to discharge the accumulated charge thereof
Data Source
AI summary
An active discharge system for electric or hybrid motor vehicles including an active discharge circuit operatively connected in parallel to a charge circuit, which is supplied by a high voltage power source and defines an electrically-charged equivalent capacitance of an electric charge, wherein the active discharge circuit is configured to discharge the electric charge accumulated by the equivalent capacitance in the event of the high voltage power source being disconnected from the charge circuit; a control circuit/device/unit/component of the active discharge circuit which are configured to receive an activation signal, suitable to activating the active discharge circuit in case of receiving the activation signal, so as to discharge the equivalent capacitance.