Transistor Control Device for Overvoltage Protection
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Solution Overview
Problem
Existing solutions for preventing overvoltages in power transistors used in motor vehicle converters either incur high costs or result in significant electrical losses, and can cause short-circuits when used in converters with series-connected switches, potentially damaging connected electrical equipment.
Innovation Solution
A control device for transistors featuring a main control circuit and an auxiliary control circuit that injects an opposing current based on the time derivative of the current flowing between the electrodes, with a detection member and an injection member to manage the auxiliary current, preventing short-circuits and reducing overvoltages by controlling the switching elements and using a programmable logic component for pulse width modulation signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing solutions for preventing overvoltages are implemented, then overvoltage protection is improved, but cost increases or electrical losses increase
Solution Approach 1:
The patent implements a feedback mechanism where the voltage across the impedance connected to the transistor's electrode is detected, and this detection triggers the auxiliary control circuit to inject current into the control electrode to turn on the transistor. This closed-loop feedback system provides reliable overvoltage protection while minimizing energy losses by only activating when needed.
Solution Approach 2:
The system uses the voltage detection across the impedance itself to trigger the protective action. The detected voltage directly controls the auxiliary circuit that turns on the transistor, making the system self-regulating and eliminating the need for external control signals or additional sensing components, thereby reducing cost and energy consumption.
2Reliability
If existing solutions for preventing overvoltages are implemented, then overvoltage protection is improved, but device complexity increases
Solution Approach 1:
The patent combines the overvoltage detection function and the transistor control function into a single integrated auxiliary control circuit. The same circuit that detects the voltage across the impedance also directly controls the transistor's switching state, eliminating the need for separate detection and control circuits and thereby reducing overall device complexity.
Solution Approach 2:
The auxiliary control circuit serves multiple functions: it detects overvoltage conditions, determines the appropriate corrective action, and executes the transistor switching control. This multi-functional approach consolidates what could be separate complex circuits into a single unified component, reducing overall system complexity.
3Reliability
If the auxiliary control circuit operates during the recovery phase, then overvoltage is prevented, but short-circuit risk increases when another transistor switches
Solution Approach 1:
The patent implements dynamic control of the auxiliary circuit through the first switching element, which is controlled by the second switching element (N-channel MOSFET). This hierarchical dynamic control allows the system to adaptively enable or disable the auxiliary overvoltage protection circuit based on real-time operating conditions, preventing short-circuits by coordinating the switching timing with the main transistor operations.
Solution Approach 2:
The first switching element acts as an intermediary between the auxiliary control circuit and the transistor's control electrode. It mediates the current flow, allowing the auxiliary circuit to safely inject current when needed while being controlled by the second switching element to prevent simultaneous conduction that could cause short-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
Effectively reduces or eliminates overvoltages during transistor switching, preventing damage to the transistors and connected equipment while avoiding short-circuits, with a cost-effective and efficient implementation.
Implementation Method 1
an auxiliary control circuit configured to, according to an auxiliary operating mode, inject an auxiliary current opposing the current flowing between the main control circuit and the control electrode of the controlled transistor
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The present invention relates to a control device (1) for at least one transistor, referred to as the controlled transistor (3), comprising: - said controlled transistor (3) which comprises a control electrode (Ec) and two other electrodes (E1and E2), - a main control circuit (5) connected to the control electrode (Ec) of the controlled transistor (3) and configured, according to a main mode of operation, to control the state of the controlled transistor (3) and, - an auxiliary control circuit (11) configured, according to an auxiliary mode of operation, to inject an auxiliary current opposing the current circulating between the main control circuit (5) and the control electrode (Ec) of the controlled transistor (3), characterised in that the control device (1) also comprises a control circuit (15) of the auxiliary control circuit (11), said control circuit (15) being configured to block or authorise the auxiliary operation of the auxiliary control circuit (11) depending on the commands from the main control circuit (5).