Transfer Molded DIP-IPM Package Improves Thermal Performance

May 1, 2010 12:00 PM
Eric Motto Application Engineer, Powerex Inc., Youngwood, PA.

The fault signal output (FO) is in an open collector configuration. Normally, the fault signal line is pulled high to the 5V logic supply with a 10kΩ resistor as shown in Fig. 5. When an over-current, over temperature condition or improper control power supply voltage is detected the DIP-IPM turns on the internal open collector device and pulls the fault line low.

DIP-IPM SYSTEM ADVANTAGES

Inverters for small AC motors used in appliance applications are required to meet stringent efficiency, reliability, size and cost constraints. Historically, many of these small inverters have utilized discrete IGBTs (Insulated Gate Bipolar Transistors) and free-wheel diodes in TO-247 or similar packages along with separately packaged HVICs (High Voltage Integrated Circuits). There are, however, several problems with this approach. One drawback is the high manufacturing cost associated with mounting and isolating multiple high voltage discrete components. Each of the discrete devices must be individually mounted using special hardware and insulating materials which typically results in a complex assembly and significant manufacturing time. In addition, relatively large and complex printed circuit designs are required to meet all of the spacing and layout requirements for the HVIC and discrete power device combination. Another equally perplexing problem is maintaining consistent performance and reliability when the characteristics of the HVIC drivers and IGBTs are not properly matched.

A better approach, realized in the DIP-IPM, is to assemble bare power chips and HVICs using a transfer molded lead frame design to maintain low cost and consistent, reliable performance. With the fully isolated DIP-IPM, mounting is accomplished with only two screws and no additional isolation material is required. The reduced manufacturing time and simplified assembly provided by the DIP-IPM will allow improvements in both cost and reliability of the finished system. Another advantage of the DIP-IPM is that the integrated HVIC and LVIC gate drive and protection functions are factory tested with the IGBTs as a subsystem. This eliminates uncertainty about the critical coordination of the electrical characteristics of these components. The end result is more consistent system performance and reliability.

The table shows the new gen. 4 large DIP-IPM line-up. Modules are available with blocking voltage ratings of 600V and 1200V which are appropriate for 100VAC to 480VAC applications. Devices with nominal current ratings of 50A to 75A at 600V and 5A to 35A at 1200V are all available in the same compact package outline. The table also shows the usable sinusoidal RMS motor current per phase for some typical application conditions. These values are calculated using the loss simulation software available from the Powerex website.

Powerex also offers devices in smaller transfer molded packages with nominal current ratings of 3A to 30A at 600V.

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