WE-AGDT Auxiliary Gate Drive Transformer
for SiC-MOSFET and IGBT
Characteristics
- Interwinding capacitance down to <1 pF
- Tiny surface mount EP7 package
- Dielectric insulation up to 4 kV AC
- Basic insulation for 568 Vrms / 800 Vpk
- Safety: IEC62368-1 / IEC61558-2-16
- AEC-Q200 Qualification
- Operating temperature: -40 °C up to +130 °C
- Common control voltages for SiC MOSFET’s
- High Common-mode Transient Immunity (CMTI)
- Flyback, LLC, Half-Bridge topologies
- Up to 6 W output power
- Wide range input voltages 6 V to 36 V
- Different unipolar and bipolar voltages
- High efficiency and very compact solution
- Reference designs with Analog Devices, Texas Instruments, STMicroelectronics and onsemi
- Reference Designs
- RD001 6 W Bipolar isolated auxiliary supply for SiC-MOSFET and IGBT gate driver
- RD002 6 W Unipolar isolated auxiliary supply for SiC-MOSFET and IGBT gate driver
- PMP30629 Isolated 2.5-W SiC & IGBT gate-drive reference design with integrated switch PSR flyback converter
Applications
- Industrial drives
- AC motor inverters
- HEV/EV charging station
- Battery chargers
- Solar inverters
- Data centers
- Uninterruptible power supplies
- Active power factor correction
- SiC-MOSFET based power converter
Products
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Auxiliary Gate Drive Übertrager
The WE-AGDT series from Würth Elektronik allows implementing discrete SiC gate driver designs easier than ever before. These standard parts are compact SMT transformers optimized for silicon carbide applications. With extremely low interwinding capacitance, the WE-AGDT helps to achieve higher Common Mode Transient Immunity (CMTI).
The series is compliant with safety standards according to IEC62368-1 / IEC61558-2-16 in addition to AEC-Q200 qualification. Reference designs are available for each WE-AGDT transformer. The complete solution is compact and capable of fully automated assembly.
Impact of Interwinding Capacitance
Importance of minimizing displacement current / common-mode current
SiC-MOSFETs can switch extremely fast, causing very high rates of rise and fall of voltage (dv/dt) across the device terminals and in turn, across the isolation barrier parasitic capacitances, which are a contribution of the transformer in the auxiliary supply (Ciso-xfmr) and the gate driver IC controller or digital isolator used (Ciso-drv).
As a result, common-mode displacement currents are generated which, if high enough, may cause loss of control of the SiC-MOSFET device as well as EMI issues, since high dv/dt also appears across PCB nodes and Earth/Chassis. The lower the parasitic capacitance, the lower the displacement currents generated, helping to prevent such issues.
Compared to regular transformers
The WE-AGDT transformers have been engineered with extremely-low interwinding capacitance in order to help the application withstand higher switching speeds (dv/dt), and with it to achieve higher efficiency as well as a smaller solution size and lower system cost.
Compared to regular, same-sized transformers, the WE-AGDT feature less than half of the parasitic capacitance, as required by state-of-the-art SiC-MOSFET and IGBT applications.
Reference Designs
SiC Gate Driver System
One of the main applications of high-voltage SiC-MOSFETs and IGBTs is in high-power AC inverters and AC-Motor drives. Such power stages are built by ‘paralleling’ several half-bridge configurations of SiC devices in order to generate the different phase currents and voltages for the load.
Each of the SiC-MOSFET devices typically has its own isolated gate driver system formed by the gate driver IC and the auxiliary supply (e.g. Würth Elektronik RD001 reference design with WE-AGDT).
A simplified schematic of an example application of a 3-phase inverter formed by three half-bridge stages paralleled and six SiC-MOSFET devices in total is shown in the image, in addition to a detail connection of the isolated auxiliary supply, isolated gate driver IC and the corresponding SiC-MOSFET device.
Applications
Products of interest
Videos
WE meet @ Digital Days 2020: SiC Gate Driver Systems with WE-AGDT series