III-Nitride Bidirectional Switches for Power Converter Loss Reduction
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Solution Overview
Problem
Conventional bidirectional switches in power converters, such as matrix converters, require complex configurations and high losses due to their non-planar and non-bidirectional nature, leading to increased costs and inefficiencies, especially when handling high voltages and currents.
Innovation Solution
The use of III-Nitride High Electron Mobility Transistors (HEMTs) in a planar configuration to form bidirectional switches, which allows for simpler integration and reduced losses by enabling a compact design with enhanced performance and flexibility, utilizing enhancement-mode or depletion-mode devices to manage high voltages and currents efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional Si IGBT configurations are used for bidirectional switching, then the device can handle high power requirements, but the device complexity increases and losses increase due to requiring multiple discrete devices and non-planar configuration
Solution Approach 1:
The patent merges multiple functions into a single planar device structure. The AlGaN/GaN HEMT integrates bidirectional switching capability, high voltage blocking, and current conduction in one planar device, eliminating the need for multiple discrete IGBTs and diodes. This merging reduces both device complexity and associated losses.
Solution Approach 2:
The patent changes the material parameter from conventional silicon to III-nitride (AlGaN/GaN), which fundamentally alters the device characteristics. This material parameter change enables planar configuration, bidirectional operation, and reduced on-resistance, simultaneously addressing both complexity and loss issues.
2Ease of manufacture
If conventional Si IGBT configurations are used for bidirectional switching, then the device can operate in power converter circuits, but the manufacturing cost increases due to requiring four or more discrete devices
Solution Approach 1:
The patent combines multiple discrete devices into a single integrated planar HEMT structure. The bidirectional switch is formed by a single AlGaN/GaN HEMT device with appropriate gate control, eliminating the need for assembling multiple discrete IGBTs and diodes, thereby simplifying manufacturing and reducing complexity.
Solution Approach 2:
The planar HEMT device performs multiple functions simultaneously: it provides bidirectional current conduction, high voltage blocking capability, and switchable operation. This multi-functionality in a single device structure greatly simplifies the manufacturing process compared to assembling multiple specialized discrete devices.
3Volume of moving object
If planar III-N HEMT configuration is used for bidirectional switching, then the device achieves compact design and reduced losses, but the device must withstand high voltages (600-1200V) which requires optimized structure
Solution Approach 1:
The patent changes the material composition parameters by using AlGaN alloy with specific aluminum content and thickness in the barrier layer. This parameter optimization creates a high electron mobility channel that can sustain high electric fields (600-1200V) while maintaining compact planar geometry, thus achieving both small footprint and high voltage capability.
Solution Approach 2:
The patent employs composite material structure of AlGaN/GaN heterointerface. The AlGaN barrier layer combined with GaN channel creates a two-dimensional electron gas that provides high current carrying capability while the layered composite structure enables voltage blocking through optimized thickness and composition, achieving both compactness and high voltage withstanding.
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
III-N HEMT-based bidirectional switches offer reduced losses, compact designs, and improved performance by enabling efficient high-voltage and high-current handling with lower on-resistance and faster switching times, reducing the complexity and cost of power converter circuits.
Implementation Method 1
an AlGaN/GaN interface that obtains a high current currying channel. The bidirectional switch operates with at least one gate that prevents or permits the establishment of a two dimensional electron gas to form the current carrying channel
Implementation Method 2
Published international patent application no. WO 2005/070009 A2 discloses a III-nitride switch includes a recessed gate contact to produce a nominally off, or an enhancement mode, device. By providing a recessed gate contact, a conduction channel formed at the interface of two III-nitride materials is interrupted when the gate electrode is inactive to prevent current flow in the device.
Data Source
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Figure 3(a)~3(d)
AI summary
Bidirectional switches are described. The bidirectional switches include first and a second III-N based high electron mobility transistor. In some embodiments, the source of the first transistor is in electrical contact with a source of the second transistor. In some embodiments, the drain of the first transistor is in electrical contact with a drain of the second transistor. In some embodiments, the two transistors share a drift region and the switch is free of a drain contact between the two transistors. Matrix converters can be formed from the bidirectional switches.