Power Transistor Supply Circuit for Stable Diagnostic Voltage
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Solution Overview
Problem
Existing power transistor devices lack an efficient and reliable power supply mechanism for their diagnostic and monitoring circuits, which can lead to delayed detection of overcurrent events and potential damage to the power transistor.
Innovation Solution
A device comprising a power transistor with a supply circuit that includes a rectifier arrangement, a charge pump, and an output capacitor, along with an auxiliary switch that is activated only when the supply voltage reaches a predefined level, ensuring that the diagnostic and monitoring circuits are powered efficiently and reliably.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple power supply mechanism is used for diagnostic circuits, then device complexity is reduced, but detection speed and reliability deteriorate due to delayed overcurrent detection
Solution Approach 1:
The patent implements preliminary action by pre-charging the output capacitor through the rectifier arrangement and charge pump before the auxiliary switch is activated. This ensures that when the diagnostic circuits become operational, the supply voltage is already at the required level, enabling immediate overcurrent detection without delay. The capacitor stores energy in advance, so when the switch closes, the circuits are powered instantly rather than waiting for voltage buildup.
2Speed
If the auxiliary switch is activated immediately, then power is supplied to diagnostic circuits faster, but the supply voltage may not have reached the required level causing unstable operation
Solution Approach 1:
The patent uses the output capacitor as an intermediary energy storage element between the rectifier arrangement and the auxiliary switch. The capacitor accumulates charge and maintains a stable voltage level, acting as a buffer that decouples the fast switching action from the voltage buildup process. When the switch closes, the capacitor immediately provides stable voltage to the diagnostic circuits, preventing instability that would occur if the switch activated before sufficient voltage was available.
3Device complexity
If no energy storage capacitor is used, then device complexity is reduced, but the supply voltage fluctuates when the power transistor switches off causing unreliable diagnostic operation
Solution Approach 1:
The patent applies beforehand cushioning by placing the output capacitor in parallel with the diagnostic circuits to cushion against voltage fluctuations. When the power transistor switches off and the control node voltage changes, the pre-charged capacitor maintains the supply voltage to the diagnostic circuits, preventing operational disruptions. This energy buffer is positioned in advance to protect the diagnostic circuits from voltage instability during power transistor switching events.
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 proposed solution enables earlier detection of overcurrent events and reduces the probability of damage to the power transistor by maintaining a stable supply voltage even when the power transistor is switched off, thus ensuring the reliability and safety of the device.
Implementation Method 1
a rectifier arrangement coupled between the device control node and an input side of a charge pump
Implementation Method 2
an output side of the charge pump is coupled to an output capacitor, wherein the supply circuit is configured to provide a supply voltage at the output capacitor
Implementation Method 3
an output side of the charge pump is coupled to an output capacitor, wherein the supply circuit is configured to provide a supply voltage at the output capacitor
Data Source
Figure 1
Figure 2
Figure 3A~4
AI summary
Devices including a power transistor having a control terminal coupled to a control node are provided. A supply circuit is coupled to the control node comprising an output capacitor and configured to provide a supply voltage at the output capacitor to supply a further circuit.