Microchip expands motor-control development tools

"Three trends are creating tremendous demand for advanced motor control solutions," said Sumit Mitra, vice president of the Digital Signal Controller Division. "First is the requirement for more energy-efficient motors; second, the increased competitiveness of markets incorporating electric motors is forcing the consideration of new control strategies; and third, the cost of DSCs has declined to the point that control strategies impractical a few years ago have become today's reality."

The company's dsPIC33 Motor Control Family, which brings the company's DSC with on-chip, 3-phase motor control PWMs to 36 devices, offers up to 128 kbytes of programmable Flash memory to accommodate large proprietary algorithms such as observer motor control models, integration of motor control algorithms with system-level control, communication stacks, and graphic libraries for displays. Two of the motor control chips contain d-a converters, which will be useful for implementing motor noise-reduction strategies. They also incorporate a user-selectable 10- or 12-bit a-d converter. The 10-bit a-d mode features up to four sample-and-hold stages that can be triggered simultaneously, and can be incorporated for sensorless control to gain improved loop performance from synchronized sampling designs.

All of the motor control DSCs feature two quadrature encoder interfaces for applications with rotor position sensors. Additionally, the DSCs have a three-phase PWM controller, plus two additional PWM outputs on a separate time base for power-factor-correction (PFC), since PFC requires a loop that is typically over 30 times faster than that required for motor control.

Libraries
PFC is becoming increasingly required for line-connected motors. Microchip's software solution for PFC can be downloaded from the company's web site (search for application note AN1106 for the description and source code download). Sensorless strategies may be the preferred approach for cost-sensitive motor-control applicatons. Four new software solutions address these needs. Sensorless FOC software for controlling PMSM motors is available (application note AN1078). FOC software for controlling ACIM motors is contained in application note AN1162. This software is advantageous for applications that benefit from high efficiency coupled with excellent torque control, such as air conditioning, refrigeration compressors, and washing machines. Two new sensorless BLDC software solutions suited to fuel pumps and appliances are also available—application note AN1083 (BLDC Control Using Back-EMF Filtering) and application note AN1160 (Sensorless BLDC Control with Back-EMF Filtering Using a Majority Function).

Development environment
The company's new PICtail Plus Motor Control daughter card (part # AC164128) provides an interconnect interface between the Explorer 16 Development Board (part # DM240001) and Microchip's high-voltage (part # DM300021) and low-voltage (part # DM300022) Power Modules. The development board, PICtail Plus motor control daughter card, appropriate power module, MPLAB ICD 2 in-circuit programmer/debugger (DV164005) and the MPLAB IDE integrated development environment comprise a complete motor control development environment.

Pricing and availability
The motor control DSCs range from $2.85 to $4.18 each in 10,000-unit quantities. The DSCs are sampling now and are expected to be available for volume production in 2Q. The motor control software and related application notes are available as a free download. The PICtail Plus Motor Control daughter card is available now for $125 and includes a dsPIC33FJ256MC710 plug-in module for use in the Explorer 16 development board.

Microchip Technology, 1-888-MCU-MCHP, www.microchip.com/DSCMOTOR