Power Transistor Switching Loss Reduction via Resonant Control
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Solution Overview
Problem
Existing power transistor switching technologies face high switching losses due to parasitic capacitance recharge and limited working ranges, with previous solutions either reducing efficiency or requiring higher driver capabilities and slower switching speeds.
Innovation Solution
A device comprising two power transistors with monitoring devices and a control unit that compares voltage potentials to determine optimal switching times, using a resonant circuit with a capacitor and coil to minimize switching losses and maintain efficiency across a broader operating range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a step-down converter with an oscillating circuit is used to enable voltage-free switching, then switching losses are reduced, but the working range is limited by the series coil in the main current path
Solution Approach 1:
The invention divides the switching function into two separate power transistors (first and second power transistors) with independent control. The second power transistor handles the main current path while the first power transistor performs the voltage-free switching operation. This segmentation allows each transistor to operate optimally within its designated function, eliminating the working range limitations imposed by placing a coil in the main current path.
Solution Approach 2:
The invention introduces a capacitor as an intermediary element connected between the drain of the first power transistor and the source of the second power transistor. This capacitor enables voltage-free switching by providing a discharge path for parasitic capacitances during the switching transition, allowing the first power transistor to switch without voltage stress while the second power transistor maintains the main current path without series coil limitations.
2Loss of energy
If an auxiliary circuit with parallel capacitance is added to enable voltage-free switching, then switching losses are reduced, but switching speed becomes slow and driver capability requirements increase
Solution Approach 1:
The invention uses dynamic control of two power transistors with independently determined switching times. The control unit monitors voltage potentials and dynamically adjusts the switching timing of both transistors based on real-time operating conditions. This dynamic approach allows for fast switching by coordinating the turn-off of the second power transistor with the turn-on of the first power transistor, eliminating the slow switching associated with fixed parallel capacitance discharge paths.
3Loss of energy
If monitoring devices and control unit are added to determine optimal switching times, then switching losses are minimized and efficiency is maintained across broader operating range, but device complexity increases
Solution Approach 1:
The invention implements feedback control through monitoring devices that continuously detect voltage potentials at key nodes in the circuit. The control unit receives this feedback information and uses it to determine the optimal switching times for both power transistors. This feedback mechanism ensures that switching losses are minimized across varying operating conditions while maintaining a relatively simple control logic that compares voltage potentials and triggers switching events based on predetermined thresholds.
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 significantly reduces switching losses and maintains efficiency even when the operating point is left, allowing for voltage-free switching without the need for high driver capabilities, thus enhancing the overall performance of the power transistors.
Implementation Method 1
a means (36, 37) following the second power transistor (32) which generates a current with a time delay when the second power transistor (32) is switched on, wherein the current changes the first voltage potential (34)
Data Source
Figure 1~2
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Figure 4
AI summary
The invention relates to a device (30) with a first power transistor (31). A drain connection of the first power transistor is connected to a supply voltage (33), and a source connection of the first power transistor (31) is connected to a first voltage potential (34) and a second power transistor (32). A drain connection of the second power transistor (31) is connected to the drain connection of the first power transistor (31), and a source connection of the second power transistor (32) is connected to a second voltage potential (35). The first voltage potential (34) is connected to a first monitoring device (39), and the second voltage potential (35) is connected to a second monitoring device (40), the first monitoring device (39) detecting the first voltage potential (34) and the second monitoring device (40) detecting the second voltage potential (35), wherein the monitoring devices (39, 40) compare the first voltage potential (34) and the second voltage potential (35) with the value of the supply voltage and actuate a control unit (42) depending on the comparison. The control unit (42) determines a switching time of the second power transistor (32), and means (43) are provided which generate a current when the second power transistor (32) is activated. The current changes the first voltage potential (34), and the control unit (42) actuates the first power transistor (31) when the first voltage potential (34) has the same value as the supply voltage (33) so that the first power transistor is switched without a voltage.