ST’s programmable PFC controller promises simpler path to digital power
In high-power applications above 1 or 2 kW, interleaved CCM PFC (continuous-current mode, power-factor correction) topologies are – ST says – mandatory to handle such power levels with reasonable magnetic volume and current split. Demand for higher efficiency, connectivity, and configuration options encourages the use of expensive and complex DSP solutions.
ST presetns its SMPS controller for interleaved boost-PFC topologies as capable of being configured quickly using its eDesignSuite online design environment, and has I²C and UART interfaces for monitoring and control. It supports three interleaved phases, which ensures low ripple currents, simplifies EMI-filter design using small-size inductors, and handles a power range from 500W to over 20 kW. STNRGPF01’s flexible, configurable phase-shedding strategy is designed to optimize the number of active phases automatically to maintain high efficiency across all load conditions.
The controller operates in CCM at fixed frequency with average-current-mode control. A hardware inner-current loop ensures accurate cycle-by-cycle regulation, while a digital proportional-integral (PI) controller manages the outer voltage loop to ensure fast dynamic response. The frequency can be programmed from a few kHz to over 300 kHz, to control either an IGBT or MOSFET output stage. Other configurable features include inrush-current limiting and PFC soft power-on.
By delivering the advantages of digital power through configuration in eDesignSuite, the device promises greater flexibility, reliability, safety, and energy efficiency in equipment such as industrial welders, motor drives, pumps, uninterruptible power supplies (UPS), industrial or consumer air conditioners, and domestic appliances such as refrigerators, washers, dryers, and cookers.
Entering the converter specifications in eDesignSuite and running the configurator automatically generates the schematic, bill of materials (BoM), and downloadable firmware to configure the IC. Designers need not understand processor memory and interrupt structures or write code to implement the required functions in a DSP.
ST has created a ‘showcase’ design in the form of a 3kW industrial SMPS evaluation board. The part, in TSSOP38, is priced from $3.50 (1000).
STMicroelectronics; www.st.com/stnrgpf01
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