GaN Switches in 3.3kW Bidirectional Interleaved CCM Totem Pole Bridgeless PFC Reference DesignApril 15, 2020 by Paul Shepard
The TIDM-02008 reference design from Texas Instruments illustrates a method to control a bidirectional interleaved continuous conduction mode (CCM) totem pole bridgeless power factor correction (PFC) power stage using a C2000™ microcontroller (MCU) and LMG3410R070. This power topology is capable of bidirectional power flow (PFC and grid-tied inverter) and it uses gallium nitride (GaN) devices, which enables higher efficiency and reduction in size of the power supply.
This reference design is suited for development of onboard chargers for electric vehicles, telecom rectifiers, drives/welding and other industrial systems, and energy storage systems.
The design supports phase shedding and adaptive dead time for efficiency improvements, input cap compensation scheme for improved power factor at light loads, and non-linear voltage loop to reduce voltage spikes under transient in PFC mode. The hardware and software available with this reference design accelerates time to market.
LMG3410R070 - GaN Power Stage
The LMG3410R070 single-channel GaN power stage contains a 70mΩ, 600V GaN power transistor and specialized driver in an 8mm × 8mm QFN package. Direct drive architecture is used to create a normally-off device while providing the native switching performance of the GaN power transistor. When the LMG3410 is unpowered, an integrated low-voltage silicon MOSFET turns the GaN device off through its source. In normal operation, the low-voltage silicon MOSFET is held on continuously while the GaN device is gated directly from an internally-generated negative voltage supply.
The integrated driver provides additional protection and convenience features. Fast overcurrent, overtemperature, and undervoltage lockout (UVLO) protections help create a fail-safe system. The device's status is indicated by the FAULT output. An internal 5V low-dropout regulator can provide up to 5 mA to supply external signal isolators. Finally, externally-adjustable slew rate and a low-inductance QFN package minimize switching loss, drain ringing, and electrical noise generation.
UCC27714 - Gate Driver
The UCC27714 is a 600V high-side, low-side gate driver with 4A source and 4A sink current capability that is targeted to drive power MOSFETs or IGBTs. The device comprises of one ground-referenced channel (LO) and one floating channel (HO), which is designed for operating with bootstrap supplies. The device features excellent robustness and noise immunity with capability to maintain operational logic at negative voltages of up to -8Vdc on HS pin (at VDD = 12V).
C2000™ MCU F28004x - Microcontroller
C2000 MCUs are part of an optimized MCU family for real-time control application. Fast and high-quality analog-to-digital controller enables accurate measurement of the current and voltage signals, and an integrated comparator subsystem (CMPSS) provides protection for overcurrent and overvoltage without use of any external devices. The optimized CPU core enables fast execution of control loop. Trigonometric operations are accelerated using the on-chip trigonometric math unit (TMU). The solution also provides an option to use the control law accelerator (CLA) on the F28004x and F2837x. The CLA is a co-processor that can be used to alleviate CPU burden and enable faster-running loops or more functions on the C2000 MCU.
Summary of Features
- Interleaved, 3.3kW, Single-Phase, Bidirectional Bridgeless CCM Totem Pole PFC Stage
- 100kHz Pulse Width Modulation Switching
- Programmable Output Voltage, 380Vdc Output Nominal
- Less Than 2% Total Harmonic Distortion (THD)
- Greater Than 98% Peak Efficiency
- powerSUITE™ Support for Easy Adaptation of Design for User Requirement
- Software Frequency Response Analyzer (SFRA) for Quick Measurement of Open Loop Gain
- Soft Starting of PWM for Reduced Zero Current Spike in Totem Pole PFC
- Software Support for F28004x Using Driver Library
- Same Source Code Maintained When Running Control Loop on C28x or CLA