3kW two-phase digital power factor correction design uses Zilog controller

July 14, 2017 //By Nick Flaherty
IXYS has developed a 3kW Two-Phase Digital Power Factor Correction (PFC) reference design based around its power transistors and rectifiers and Zilog 8-bit microcontroller.

The 3kW AC-DC converter uses the Z8F6481 microcontroller, part of the Z8 Encore family, as an active PFC controller and employs a two-phase interleaved conversion architecture. It incorporates the digital inrush current concepts and design principles from the IXRD1002 High Power Digital Inrush Current Controller and the IXRD1004 High Power Two-Phase Digital Power Factor Correction.

The input voltage of the PFC is at 240VAC while the output voltage is 650V. The maximum output power is 3kW, and the switching frequency ranges from 80kHz to 100kHz. The output voltage ripple is less than 5 percent at the full load. Other features include overload, overvoltage, and brownout protection, soft start, and power good status. The switches and the boost diodes use the IXYS 850V Ultra-junction Power MOSFETs IXFH50N85X and IXFH30N85X, respectively. The total power dissipated in these MOSFETs is less than 54W at 3000W output power, making the PFC highly efficient.

"This reference design demonstrates digitizing power management circuits using standard MCU's to achieve state of the art control and energy efficiency," said Steve Darrough, VP of marketing at IXYS.  "The Zilog Z8 Encore! family is a proven robust MCU especially for power control applications and is incorporated in an innovative circuit using the efficient IXYS 850V power MOSFET to achieve cost effective  efficiency in a wide power range." 

The design consists of a microcontroller module, main power board, and auxiliary board. Implemented as an add-on device, the MCU module contains a connector for programming, which should be done before the entire system is switched on. The four layer, surface mount main power board provides easy access to test points and can be powered from a 50Hz/60Hz 220/240V AC source.

Suitable for high power (3kW and above) AC-DC converters with active PFCs, this design can serve as a platform for developing a variety of power management solutions such as electric vehicle chargers, air conditioning systems, high-power LED lighting, and wielding equipment.

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