Search the Archives
Maintenance-prone hydraulics, belts, gears, clutches, and pulleys may soon be eliminated from a variety of industrial control systems, thanks to a powerful new microprocessor from Texas Instruments (TI). The new electronic microprocessor combines an extensive set of motor control features with enough processing power to execute complex control formulas needed for adaptive and variable speed control of brushless electric motors. Because these computer chips allow control system designers to reduce the use of mechanical coupling elements, factory automation systems can be made smaller, cheaper, quieter, and more energy efficient.
Known as a digital signal processor, or DSP, this advanced computer chip adds and multiplies tens of millions of complex formulas every second. A DSP chip is 10 to 50 times more powerful than other computer chips in handling math intensive tasks, and it enables numbers to be processed in "real time." TI is the world's leading provider of DSP solutions, having patented its first DSPs in 1982.
The rapid growth of DSPs, a market expected to reach $9 billion by the year 2000, is enabling the creation of new and improved products in industries such as industrial control. Because TI's TMS320C240 DSP enables robust variable speed motor and motion control, inexpensive AC motors can be connected, for example, directly to paper production, textile manufacturing, and food processing systems that have traditionally used hydraulics or single-speed motors coupled to belts, pulleys, clutches, or gears to collectively vary controller speeds. Such mechanical couplings have long been inexpensive and well understood control mainstays, but their numerous disadvantages make their elimination from industrial applications desirable. Control systems that use the 'C240 in direct drive electronics can be made quieter, and can reduce power consumption by as much as 40 percent. DSP-enabled motor systems may also weigh far less than their mechanical predecessors, can be easier to install and maintain, and can occupy less physical space, placing fewer design constraints on automation system design engineers.
Because the 'C240 DSP is an "intelligent" control processor, the all-electronic control systems enabled by the chip can be programmed to behave far more flexibly than traditional mechanical systems. In a modern, automated soft drink bottling facility, for example, syrup being piped to a bottling unit must be held under constant pressure. DSP control of a variable speed pump motor allows very fine control over this kind of process, with far greater precision and consistency than through mechanical means.
In general, the DSP allows control cycles to use electronically programmed speed changes to specifically optimize motor speed for different kinds of operations. The DSP uses advanced control formulas, including soft starts after motor direction reversal, which can significantly lower motor induced vibration, making motor driven automation systems quieter and less prone to destructive wear.
TI's breakthrough 'C240 DSP controller is a DSP solution that includes a 20 MIPS processor CPU that runs sophisticated motor control formulas, a specialized motor control circuit called an "event manager," plus a comprehensive group of motor control peripherals, all on a single microprocessor.
Integrated with the DSP core, the 'C240's unique motor control event manager directly supports generation of pulse width modulated (PWM) outputs to drive the motor power amplifier, and contains motor control features that include timers, comparators, dead-band generation logic, a state space vector generator, and direct inputs for optical encoders. Additional chip peripherals include two serial interfaces, dual analog-to-digital converters, digital input and output lines, a low-voltage detector, and on-chip memory.
The processing power of the 'C240 DSP allows the use of math-intensive motor control algorithms, which enable sensorless and adaptive controller designs to be used in mainstream product designs for the first time. System cost may be lowered by reducing part count, such as external sensors, memory chips, and mechanical gearing and through the use of inexpensive motors such as DC brushless, switched reluctance, and AC induction. A 'C240-based system can also provide improved energy efficiency and reliability, along with reduced vibration and noise.
Brushless motors offer many advantages over traditional brush-type motors including lower cost, lighter weight, and reduced maintenance, but they require real-time execution of mathematically intensive control algorithms for robust control. The 'C240 supports this need by enabling the use of complex DSP-based formulas which allow precise, adaptive control of brushless motors without requiring expensive sensors for position and loading feedback.
'C240-based motor systems can provide precise torque control and
speed regulation of brushless motors, and superb response to rapid
speed or load changes, but without the weight, high maintenance
costs, and energy consumption of a DC brush motor system. These
advanced DSP controllers for brushless motors can deliver full
torque, even at standstill, and because they are brushless, are
well suited to the harsh or wet process, chemical, and petrochemical
environments. For the same reason, AC motors are ideal in food
and pharmaceutical processing applications where washdown procedures
must occur.
Reader Inquiry: 1-800-477-8924, ext. 5300
Please refer to Profile # SPR236
TI Home
Search
Semiconductor Home