PCIM'S theme: A lean, mean power machine

New European Directives demand that consumer products become increasingly power frugal. That's incentive enough for the power semiconductor industry to create smaller and more capable—as well as increasingly efficient—components and systems. At this year's PCIM Exhibition and conference in Nuremberg, Germany, these themes dominated the new power electronics technology on display.

Infineon, for example, took the opportunity to show its latest power modules designed for industrial applications (Fig. 1). These compact IGBT (insulated gate bipolar transistor) modules make possible power-converter system solutions that are intended for motor-drive, windmill, power-supply, and even heating-system applications in trains.

Called PrimePACK, the modules are based on an interesting packaging concept that takes advantage of the company's new-generation IGBT4 chips.

The module's design moves the IGBT chips closer to the baseplate's screw-fastening points. This creates a low thermal resistance between baseplate and heatsink, which helps reduce internal stray inductance by approximately 60%. This is important because it avoids overvoltage spikes.

The design also improves heat distribution, resulting in a low thermal resistance for the whole system. At +150°C, the maximum operating temperature is higher than the +125°C achieved with previous modules.

Infineon was also able to lower the minimum storage temperature from –40° to –55°C. The company believes that in power-converter applications, these modules can boost nominal current by approximately 20%.

Embracing the opportunity for energy conservation, Tier Electronics LLC and Texas Instruments announced that TI's DSP-based TMS320 C2000 controllers will be a key component in Tier's motor-control system for washing machines and other white goods.

Many of today's white goods use conventional single-phase motors that require simple control algorithms and hardware, but are noisy, bulky and waste energy. To avoid this problem, designers have to maximise efficiency, making sure that motors are used to the fullest extent to minimise the amount of power wasted.

In Tier's system, designers can link the processing ability of the C2000 controller with intelligent power modules and pressure-stamped heat sinks, delivering up to 30% better efficiency. Integration of the C2000 controller enables the use of a multiphase ac motor that can be controlled with an adaptive-based field-oriented control (AFOC).

Multi-phase ac motors controlled with an adaptive algorithm are smaller, run more quietly, and provide precise speed and torque control based on a machine's load to avoid wasting energy. The AFOC scheme strives to maintain an angle between the rotor flux and the stator flux that's optimised to improve motor efficiencies, and at the same time actively control the torque. When this is accomplished, overall performance improves significantly. The AFOC vector control reduces the voltage and current peaks and valleys associated with scalar and traditional FOC control, which also produces quieter appliances.

In addition, digital signal controllers deliver improved pulse-width-modulation control compared to conventional control systems, keeping a motor's total harmonic distortion (THD) at a minimum over a wide operating range. This also leads to lower operating temperatures, higher efficiency, better power factor ratings, and lower materials costs, particularly regarding the amount of copper required for the motor.

National Semiconductor used PCIM to introduce a 100V halfbridge PWM controller, which it claims has the industry's highest level of integration. The LM5035, the newest member of the high-voltage LM5000 family, integrates a voltage-mode PWM controller with high-side and low-side 2A peak gate drivers, plus two programmable, secondary-side synchronous rectifier FET drivers.

Programmable control of the rectifying switches allows designers to fine-tune their timing relationship to optimise overall power efficiency. Applications for LM5035 half-bridge power supplies include telecommunications, data communications, and industrial control systems, where power density and efficiency are primary concerns.

Toshiba Electronics Europe announced that its TLP7xx family of tiny photocouplers has three new members, each of which provides totem-pole outputs (Fig. 2). Supplied in SDIP packaging—making them 50% smaller than previous devices—the new photocouplers suit a variety of applications, such as CAN bus interfaces, high-speed data transfer, and intelligent power-module signal isolation.

The new photocouplers integrate a GaAlAs infrared LED and a high-gain, high-speed photodetector within a surface-mount, 6-pin SDIP package measuring 6.8mm × 4.5mm × 3.6mm. Isolation voltage rates 5kVRMS (minimum), while the totem-pole output stage provides both source and sink driving functionality.

Swiss-based Maxwell Technologies introduced BOOSTCAP Energy- and Power-type C-Cell ultracapacitor cells and multi-cell packs. The cells provide what the company describes as high-performance, "life-of-the-system" alternatives to batteries for an extensive range of industrial and transportation applications.

According to Dr. Richard Balanson, Maxwell Technologies' president and chief executive officer, "the new 2.5V cells have the same external dimensions, but weigh one-third as much as the familiar C-size battery, and are designed for easy mounting on printed-circuit boards and in other electrical devices and systems. Representative applications include industrial robotics, actuators, telecommunications power buffering and backup, aircraft door and air-bag actuation, distributed power nodes for automotive subsystems, and solar-energy-system augmentation."

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