Transistor Cascade High-Voltage Discharge Safety Circuit
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Solution Overview
Problem
Existing inline ignition systems for active systems take too long to return to a safe state, as the high-voltage capacitor discharge time is typically over 5 seconds, which is not sufficient for quick system disarmament, and the discharge of the trigger capacitor only prevents triggering rather than fully disarming the system.
Innovation Solution
A safety device with a transistor cascade and interbase resistors connected in parallel with the high-voltage capacitor, allowing for rapid discharge of the capacitor, utilizing a Darlington circuit for increased current amplification and an optocoupler for galvanic isolation, enabling quick placement of the ignition system in a safe state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a high-voltage capacitor is discharged via bleed resistors with discharge resistance in the range of approx. 50 megaohms, then power loss at high voltage is kept low, but the discharge time is approx. 5 seconds which is too long for quick system disarmament
Solution Approach 1:
The patent divides the discharge function into two distinct paths: a high-impedance bleed resistor path for normal power loss management and a low-impedance transistor cascade path for rapid discharge. This segmentation allows the system to optimize for both low power loss during operation and fast discharge when needed, resolving the contradiction between energy efficiency and discharge speed.
Solution Approach 2:
The patent implements a dynamic discharge system where the discharge resistance can be changed on demand. During normal operation, the high-impedance bleed resistors maintain low power loss. When rapid discharge is required, transistors are activated to dynamically switch to a low-impedance discharge path, achieving discharge times of less than 40 milliseconds.
2Loss of time
If only the trigger capacitor is discharged to prevent triggering, then the discharge time is short, but the high-voltage capacitor remains fully charged and the system is not truly disarmed
Solution Approach 1:
The transistor cascade circuit serves multiple functions: it can discharge the trigger capacitor quickly to prevent triggering, and it can also discharge the high-voltage capacitor completely for full system disarmament. This multi-functionality resolves the contradiction by providing a single mechanism that achieves both short discharge times and complete system disarming.
Solution Approach 2:
The patent prepares the discharge path in advance by having the transistor cascade ready to activate. When disarmament is required, the system immediately activates the pre-configured discharge path, achieving rapid discharge of both capacitors without delay, thus ensuring both speed and completeness of disarming.
3Loss of time
If a transistor cascade is used to discharge the high-voltage capacitor rapidly, then the discharge time is reduced to less than 40 milliseconds, but the system complexity increases
Solution Approach 1:
The patent uses interbase resistors as intermediary elements to distribute the high voltage evenly across the series-connected transistors. These resistors prevent voltage breakdown across individual transistors and simplify the control logic, allowing the complex transistor cascade to be managed through simple base current activation, thus reducing overall system complexity.
Solution Approach 2:
The patent replaces complex mechanical or electronic discharge switching mechanisms with a transistor cascade controlled by simple base current signals. This substitution simplifies the control system while achieving rapid discharge, as the transistors can be switched on and off quickly through electrical signals without mechanical movement or complex timing circuits.
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 the high-voltage capacitor to be discharged rapidly, achieving a safe state in less than 40 milliseconds, effectively disarming the system and eliminating the need for a secondary winding in the high-voltage transformer, thus improving system responsiveness and efficiency.
Implementation Method 1
The series-connected plurality of first transistors is connected in parallel with the high-voltage capacitor. The high-voltage capacitor can be discharged quickly if necessary via the majority of the first transistors.
Implementation Method 2
In order to achieve an even distribution of the high voltage over the plurality of transistors, interbase resistors are inserted.
Implementation Method 3
At least one first transistor of the plurality of first transistors is connected to at least one second transistor in a Darlington circuit. This has the advantage that the current amplification factor of a single transistor and thus the discharge current is increased.
Implementation Method 4
utilizing a Darlington circuit for increased current amplification and an optocoupler for galvanic isolation, enabling quick placement of the ignition system in a safe state.
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
A safety device (100) for an operating system with an ignition system is specified. The safety device comprises at least one high-voltage capacitor (C1), at least one first leakage resistor (R1), and at least one second leakage resistor (R2). The first and second leakage resistors are each connected in parallel with the high-voltage capacitor. The safety device comprises a plurality of first transistors (T1 - T8) connected in series. One base of each first transistor of the plurality of first transistors is connected to a resistor (R11 - R18). The series-connected plurality of first transistors is connected in parallel with the high-voltage capacitor. At least one transistor (T1) of the plurality of first transistors is connected to a signal generator. The high-voltage capacitor can be rapidly discharged via the plurality of first transistors if required.