Low Cost Implementation
Scalable Power Designs
Hardware Mapping To Different Applications
The advances of modern technology are bringing down the cost of high performance micro controllers. These combined with a rich set of suitable peripherals enable digital control of SMPS at feasible mass volume prices. The designers no longer need to work with complex and over-sized DSPs, while adapting to the intricate implementations of different vendors, to implement flexible modulation schemes and process the calculations in a time-efficient manner. The low end of ARM® Cortex™-M family thus are very suitable candidates for this task as they are widely deployed and proven, meaning the support and development structure is in place and engineers are comfortable working with them. Control algorithms such as traditional PID and other techniques may be programmed in to achieve improved system dynamics and deployment flexibility. Combined with well balanced peripheral sets and with the addition of analogue circuitry for sampling data these rise to the task of controlling a new generation of SMPS with unrivaled efficiency figures and increased power density.
The ICERGi digital controllers are implemented as compact control card PCBs with integrated gate drivers for ready placement on main boards of systems. They are based on the cost-effective ARM® Cortex™-M0 processors because of their proven reliability, extensive deployment and rich peripheral sets. ICERGi controllers enable cost-effective multilevel power conversion from 300W to 3kW and are readily applied to different typologies and variants.
ICERGi has developed a power conversion engine based on a multilevel conversion leg. This can be used as Battery Charger, Active power Filter, PFC or Grid-Tied Inverter. In fact the hardware for the latter two is identical and the functionality is completely defined by proprietary firmware. Power scaling is determined by transistor selection and heat dissipation in a given application.
For more information on scalable and mappable hardware please see the following white paper(s):
WP-002 - Software-Defined Power Conversion
ICERGi PFC/Inverter Controllers have hardware that is compatible with operation of a module either as a PFC stage or as an Inverter with appropriate software provision. Proprietary algorithms are used, optimizing transient response and current THD with low values of bulk capacitance.The control diagram is illustrated in Fig. 1.
This control card integrates TruDrive™ technology, a high performance low cost gate drive solution, to drive stacked low voltage transistors in a 3-Level configuration. Drivers for Thyristors/Synchronous Rectifiers are also included in the module.
The circuit block is implemented in a 26.3 x 35.3 mm PCB, with pin-out as shown in Fig. 2. When coupled with a power board, this forms a module intended for vertical mounting on a main PCB board.
Fully integrated digital controller and isolated gate driver solution for conventional and 3-level totem-pole boost PFC
Enable 99% efficiency using standard Silicon FETs and capable of working with Wide-Band-Gap devices
Allow wide ranges of power (300W – 3kW) and applications including industrial, medical, and server markets
Inherent low-cost and best-in-class performance of ICERGI Digital Control Algorithm and Gate Driver
Advanced algorithms allow excellent transient response with small bulk capacitance
Supports low-power burst-mode operation
UVLO for managed startup
Full protection suite with monitoring of bulk capacitor voltage, input voltage and current
The ICERGi LLC controller card (IC93-002) provides low-cost isolated gate drivers and full-functionality control for the isolation stage in AC-DC power conversion. This implementation is suited to operation of four sets of series-stacked 150V FETs to provide a three-level implementation as shown in Fig. 3.
It may be used independently or in association with a an ICERGi PFC stage.
Line sensing is undertaken to effect UVLO and OVLO functionality, with overcurrent detection allowing rapid response to short-circuit events. A conservative design approach also raises the frequency immediately on detection of an overcurrent conduction. This provides protection against capacitive mode operation, and also the low voltage devices have inherently better reverse-recovery characteristics which makes them much more tolerant to capacitive mode conditions.
Pins are also provided for signalling with a Power Factor Correction stage, allowing transmission of a power-fail warning signal. Standard Enable, Feedback and Overvoltage protection functionality is also implemented using optocouplers.
Drive to the primary devices is integrated at low cost using ICERGi gate driver ICs (IC70-001). A small transformer can be used to provide the isolation as needed for drive of secondary-side rectifiers.
The circuit block is implemented in a 26.3 x 35.3 mm PCB, with pinout as shown. This is intended for side mounting on to a main PCB board and for usage in association with another card housing power switching devices.
Compact circuit block with built-in isolated gate drivers and full functionality for control of 3-level isolation stage using LLC operating mode
Enable usage of low voltage (150V) MOSFETs allowing high switching frequencies > 250kHz
Allows smaller transformer and EMI filters
Control of Synchronous Rectifiers from Primary Side
Supports low-power burst-mode operation
Minimal current consumption (<100uA) in pre-start-up operating mode
UVLO (typically set at 400V) so as to allow clean start of PFC stage and subsequent start of isolation stage.