Appliance Design - January 2009 - (Page 45)

motorS dvCE/dt values. This is especially critical at: 4Low junction temperatures (e.g. TVJ = –25 DegC). 4Very low currents (e.g. IC = 0.5 A). 4High supply voltages (e.g. VDD = 20 V). 4High DC link voltages (e.g. VDC > 400 V). This extended gate drive circuit offers high reliability over the product lifetime, because it eliminates the possibility of the shoot-through currents. These cause higher switching losses, which may lead to thermal runaway or increased electromagnetic interference (EMI). The B2-series according to Fig. 3 is an extension of the B-series and incorporates an additional internal pull-up and clamping circuit in order to eliminate the need for external clamping. The B2-series is therefore the only CIPOS which is able to interface directly to any microcontroller even down to the 3.3 V level. The PCB for a motor drive PCB can now be designed with a higher power density, because fewer components are required on the PCB. Fig. 5 shows an internal shunt resistor (Rsh) for current measurement incorporated in the closed emitter series at pin 12 of this intelligent power module. It provides a direct protection against over-currents. The shunt signal passes an RC low pass filter with a time constant of approximately 1µs. This CIPOS also provides a fault feedback signal in the case of over-current or supply under-voltage. Demonstrating the actual design flexibility and custom capability of CIPOS, an appliance customer requested a customized design of CIPOS for its newest low cost, high-speed, two-phase, switched-reluctance motor drives. Flexibility in design and manufacturing produced a CIPOS design equipped with four IGBTs, which have a DC current rating of 22 A at 25 DegC and 15 A at 80 DegC. This CIPOS provides a direct access to the NTC thermal sensor and also includes a current sense resistor. One advantage of the internal thin film Silicon-On-Insulator gate driver IC is that it provides ruggedness on negative transient voltages to -50V with respect to module ground reference since no parasitic thyristor structures are present in the device. Therefore, no parasitic latch-up may occur at all temperature and voltage conditions ensuring a very stable design even under rough conditions — critical in all CIPOS configurations. Long term reliability of power semiconductors is directly related to their temperature. In CIPOS, removing the heat from the silicon die is accomplished by mounting the IGBT transistors and free-wheel diodes to the DCB substrate: two layers of copper bonded to an Alumina (Al2O3) ceramic base. The bottom copper is exposed and contacts the heatsink in the final product. The copper layer on top of the ceramic is patterned to optimize current flow. This thin DCB closely matches the thermal coefficient of expansion of silicon providing much better power cycling capabilities and thermal dissipation as compared to IMS. Fig. 6 shows the DCB layout together with a thermal image of a single-IGBT heating from the IKCS12F60B2A. Heatsink temperature during this evaluation is 100 DegC; the single-IGBT power dissipation is shown operating at maximum collector current, showing good heat spreading. The high insulation voltage of the Alumina, 2,500 V, also results At LCR, we recognize that your application may require some different specifications than what comes out of a catalog. That's where our hard-earned experience, agile engineering and flexible manufacturing systems go to work for you. LCR can quickly and efficiently produce motor controls that fit your need, so you don't have to make your product fit the control. LCR's stock of controls are made for a wide variety of motors, including: DC Brush Brushless ■ AC Induction ■ Universal ■ Shaded Pole ■ Split Phase AC ■ You Name It! ■ ■ As a leader in the EMI field, our motor controls are designed "EMI-friendly" . And they can all be customized to meet your specific requirements. Let LCR build the controls you need, so you can build the product you want. Call LCR today to see how we can make your job easier. 9 South Forest Avenue Norristown, PA 19401 (800) 527-4362 sales email: sales@lcr-inc.com w w w. l c r- i n c . c o m applianceDESIGN January 2009 45 9/16/08 1:50:50 PM www.applianceDESIGN.com AD10084LCR.indd 1 http://www.lcr-inc.com http://www.lcr-inc.com http://www.appliancedesign.com

Table of Contents Feed for the Digital Edition of Appliance Design - January 2009

Appliance Design - January 2009 Contents Editorial Shipments/Forecasts News Watch Supplier Spotlights Commercial Appliances Plastics & Parts Electronics Motors Design Marts Association Report: NAFEM Advertiser’s Index

Appliance Design - January 2009

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.