Equivalent Transistor for Three-Level Inverter Switching Speed
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Solution Overview
Problem
Transistors with parasitic diodes have a poor reverse recovery feature, leading to a long reverse recovery time and low switching speed due to the slow release of stored electric charges, which affects the performance of switching circuits.
Innovation Solution
The implementation of an equivalent transistor structure comprising a first transistor, a second transistor, and a diode, where the diode is connected in parallel to the transistors, allowing current to flow through the diode with a good reverse recovery feature, thereby reducing reverse recovery time and increasing switching speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transistor with a parasitic diode is used, then the transistor can be protected from high voltage overshoot, but the reverse recovery time is long and switching speed is low
Solution Approach 1:
The patent divides the single transistor structure into two parallel transistors (first transistor and second transistor) with their respective parasitic diodes. This segmentation allows the circuit to utilize the fast reverse recovery characteristic of one parasitic diode while the other transistor remains in cutoff state, thereby achieving both protection and fast switching speed.
2Reliability
If a parasitic diode is used in the transistor, then high voltage protection is achieved, but the reverse recovery feature is poor
Solution Approach 1:
The patent dynamically controls the switching states of the first and second transistors. During reverse recovery, one transistor is kept in cutoff state while the other handles the current, dynamically optimizing the reverse recovery process to be faster than traditional single-transistor designs while maintaining high voltage protection.
Data Source
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AI summary
This disclosure relates to an equivalent transistor and a three-level inverter, and pertains to the field of power electronics technologies. The equivalent transistor includes a first transistor, a second transistor, and a diode. A source electrode of the first transistor is electrically connected to a source electrode of the second transistor; a gate electrode of the first transistor is electrically connected to a gate electrode of the second transistor; and one end of the diode is electrically connected to a drain electrode of the first transistor, and the other end of the diode is electrically connected to a drain electrode of the second transistor. According to this disclosure, a reverse recovery time can be reduced, and a switching speed of the equivalent transistor can increase.