SiC Bidirectional Switch Layout for Lower Switching Loss
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Solution Overview
Problem
Conventional power conversion apparatuses using bidirectional switches face inefficiencies due to high switching device losses and reverse-blocking limitations, which affect the overall performance and reliability of power conversion processes.
Innovation Solution
The use of silicon carbide transistors with integrated diodes in a bidirectional switch configuration, where the diodes are connected in series and parallel to reduce on-resistance and prevent reverse current flow, along with a control unit to manage the switching states of these transistors, enhances the efficiency and reliability of power conversion by minimizing switching losses and preventing reverse voltage issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional bidirectional switches are used, then the power conversion apparatus can operate bidirectionally, but switching device losses are high
Solution Approach 1:
The patent changes the material parameter from conventional silicon-based transistors to silicon carbide (SiC) transistors. This material parameter change reduces the on-resistance and switching losses significantly, while maintaining the bidirectional power conversion functionality and improving overall system reliability.
Solution Approach 2:
The patent employs a composite structure combining silicon carbide transistors with integrated diodes. This composite material approach leverages the superior electrical properties of SiC to achieve both low switching losses and high reliability in the bidirectional switch configuration.
2Reliability
If conventional bidirectional switches are used, then the circuit structure is simpler, but reverse-blocking capability is limited
Solution Approach 1:
The patent merges the transistor and diode functions into an integrated SiC transistor structure with built-in diodes. This combination provides both the active switching capability and the passive reverse-blocking capability in a single device, eliminating the need for separate reverse-blocking components and reducing overall circuit complexity.
Solution Approach 2:
The SiC transistor with integrated diodes serves multiple functions simultaneously: it acts as the main switching element, provides reverse-blocking capability through the integrated diodes, and enables bidirectional power flow. This multi-functionality resolves the contradiction between improved reverse-blocking capability and device complexity.
3Loss of energy
If diodes are added to prevent reverse current flow, then reverse recovery losses are reduced, but the device structure becomes more complex
Solution Approach 1:
The patent integrates diodes directly into the SiC transistor structure, merging the switching and rectification functions into a single device. This integration reduces reverse recovery losses by optimizing the diode characteristics while avoiding the complexity of separate diode configurations and additional external components.
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
This configuration reduces switching losses and enhances the reliability of power conversion by lowering the on-voltage of the diodes and improving the avalanche withstand capability, thereby improving the overall efficiency and reducing reverse recovery losses.
Implementation Method 1
silicon carbide transistors with integrated diodes in a bidirectional switch configuration, where the diodes are connected in series and parallel to reduce on-resistance and prevent reverse current flow
Implementation Method 2
a control unit to manage the switching states of these transistors, enhances the efficiency and reliability of power conversion by minimizing switching losses
Implementation Method 3
The power conversion apparatus generates output power from input power by switching one or more bidirectional switches
Data Source
AI summary
A bidirectional switch, having: a first silicon carbide transistor; a first diode which is provided in series with the first silicon carbide transistor, and of which on voltage is lower than that of a built-in diode of the first silicon carbide transistor at a rated current of the bidirectional switch; a second silicon carbide transistor provided in parallel with the first diode; a second diode which is provided in series with the second silicon carbide transistor and in parallel with the first silicon carbide transistor, and of which on voltage is lower than that of a built-in diode of the second silicon carbide transistor at the rated current of the bidirectional switch; and a connection line which connects a first connection point between the first silicon carbide transistor and the first diode, and a second connection point between the second silicon carbide transistor and the second diode, is provided.