Power Electronics

Integrating Analog, Digital and Power for Motion Control

To overcome the shortcomings of conventional motor control solutions, International Rectifier (IR) has combined the building blocks, which were earlier developed independently, into an integrated design platform for motor control systems. All the required hardware and software, along with digital control, high-voltage analog, and power stages, have been joined under a single rostrum to deliver an unprecedented integrated design platform for motion control applications. Called iMotion, this application-specific platform offers all the elements — codesigned and codeveloped for motion control.

This development system includes all the requisite parts that have been optimally tied together to achieve a design flow that requires no coding to configure the motor control algorithms and offers proven designs for analog and power stages, according to David Tam, IR's vice president of consumer and industrial business unit. It gives designers a complete toolset for rapid prototyping of motor control system, said Tam. Thus, iMotion simplifies design, slashes motion control system cost, and cuts time-to-market.

In essence, this platform includes a configurable digital control engine with proprietary motion control algorithms, mixed-signal high-voltage ICs, and power modules incorporating latest non-punch-through (NPT) IGBTs and packaging technologies (see the figure). To ease its use, IR has readied specific products for each section, with proprietary sensorless and encoder based servo algorithms developed in-house that can be easily implemented in the FPGA of the digital control engine. IR has also developed an IP library of licensable object code for sensorless and encoder based motion control algorithms. While the IRMCO203 IP library is for sensorless control of permanent magnet motors, IRMCO201 is for encoder based servo applications.

Likewise, the analog section of iMotion uses high-voltage ICs, while the power stage is based on the latest non-punch-through (NPT) IGBTs and PlugNDrive integrated power module technology. The high-voltage analog ICs include linear current sensing chip IR2175 and 3-phase inverter driver IC IR2136. Designed for 230V 3-phase ac or brushless dc industrial drives, the IR2175 provides current feedback information and features fast frequency output for higher bandwidth and faster acceleration required in demanding servo motor control applications. It eliminates the use of external opto- or Hall-effect sensors. Offering a 2 ms overcurrent shutdown capability with a wired-OR connection, it comes in two standard packages, SO-8 and 8-pin DIP. Similarly, IR2136 includes three high-side MOSFET and three low-side IGBT high-voltage gate drivers with a range of protection functions. Providing 120mA/250mA output source/sink current, it offers a dead time of 250ns, and a typical turn-on/turn-off time of 400ns. It comes in 28-lead DIP and SOIC packages and 44-lead PLCC. The analog stage chipset serves as a bridge between the digital control engine and power stage in the iMotion platform.

The integrated PlugNDrive power module is a complete power stage for 3-phase power inverter motor drives in one compact package. The 16A rated IRAMX16UP60A is the newest member of PlugNDrive family, crafted for 750W to 1.2kW variable speed motor drive applications. It combines IR's low loss, NPT short circuit-rated IGBT with a 3-phase, high-voltage, high-speed driver IC and more than 20 individual parts in one isolated unit. With a few external components and one microcontroller, it enables a complete variable speed motor drive. EMI emissions are minimized due to shorter connection routing, optimized component layout, and internal shielding. Housed in an SIP2 package, it's pin-to-pin compatible and offers same length and assembly requirements as the smaller 10A version.

Complete development systems incorporating the libraries, FPGA based control engines, mixed-signal high-voltage ICs and power modules have been readied for each type of motion control application. Thus, IRMCS203 is a development system crafted for sensorless motor control, while IRMCS201 is a development system for encoder based servo motor control.

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