Authors: Chung Astro Applications Tresna Hidajat Strategic Marketing T

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Using TMS320C24X Controller Optimal Digital Control
Authors: Chung Astro Applications Tresna Hidajat Strategic Marketing Texas Instruments Taiwan Limited
Digital Signal Processing Solutions January 1998
IMPORTANT NOTICE
Texas Instruments (TI) reserves right make changes products discontinue semiconductor product service without notice, advises customers obtain latest version relevant information verify, before placing orders, that information being relied current. warrants performance semiconductor products related software specifications applicable time sale accordance with TI's standard warranty. Testing other quality control techniques utilized extent deems necessary support this warranty. Specific testing parameters each device necessarily performed, except those mandated government requirements. Certain application using semiconductor products involve potential risks death, personal injury, severe property environmental damage ("Critical Applications"). SEMICONDUCTOR PRODUCTS DESIGNED, INTENDED, AUTHORIZED, WARRANTED SUITABLE LIFE-SUPPORT APPLICATIONS, DEVICES SYSTEMS OTHER CRITICAL APPLICATIONS. Inclusion products such applications understood fully risk customer. products such applications requires written approval appropriate officer. Questions concerning potential risk applications should directed through local sales office. order minimize risks associated with customer's applications, adequate design operating safeguards should provided customer minimize inherent procedural hazards. assumes liability applications assistance, customer product design, software performance, infringement patents services described herein. does warrant represent that license, either express implied, granted under patent right, copyright, mask work right, other intellectual property right covering relating combination, machine, process which such semiconductor products services might used.
Copyright 1997, Texas Instruments Incorporated
TRADEMARKS
trademark Texas Instruments Incorporated. Other brands names property their respective owners.
CONTACT INFORMATION
TMS320 HOTLINE TMS320 TMS320 TMS320 email
(281) 274-2320 (281) 274-2324 (281) 274-2323 dsph@ti.com
Contents
Abstract Product Support World Wide Introduction. Analog Digital Control Systems Benefits Microcontrollers Benefits DSP-Based Control Control System Digital Controller Requirements. Processor Requirements TMS320C24x Family Optimal Digital Control System Solution Applications Summary References
Figures
Figure Figure Figure Figure Figure Typical Control System. Block Diagram Digital Control System. TMS320C240 Architecture. TMS320C240 Event Manager Module TMS320C240 Analog-to-Digital Converter Module
Using TMS320C24X Controller Optimal Digital Control
Abstract
Although traditional microcontrollers include necessary peripherals provide solutions digital control applications, they lack both performance architecture needed perform real-time, math-intensive, advanced control algorithms desired bandwidth. This application report describes features Texas Instruments (TITM) TMS320C24x digital signal processor (DSP), cost, single chip solution optimal digital control system applications. This solution tribute integration only powerful core, also specialized digital control circuit (known event manager) comprehensive desired peripherals. Because high bandwidth signal processing ability DSP, this controller help designers easily achieve robust, precise, adaptive, sensorless digital control system.
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Product Support World Wide
World Wide site www.ti.com contains most date product information, revisions, additions. Users registering with TI&ME build custom information pages receive product updates automatically email.
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Introduction
Saving energy become concern because continuing increase energy usage. Increased efficiency reduces capital spending utility companies building additional power plants, which turn reduces utility costs customers. remain competitive, power plant administrators pressured only reduce costs imposed governments power plant lobbies, also answer power consumption reduction radiation reduction issues. These constraining factors result need enhanced algorithms. addition system cost reduction, technology makes digital control more practical also offers high level performance. TMS320C240 part generation processors addressing digital motor control power conversion optimization. TMS320C240 specifically designed digital motor control power conversion segments, combining fixed-point core with microcontroller peripherals single chip solution.
Analog Digital Control Systems
Early solid state controls consisted hardwired analog networks built around operational amplifiers. Analog controls offer distinct advantages over digital systems:
Higher speed control processing input data real time Higher resolution over wider bandwidths because infinite sampling rates
However, there several drawbacks analog systems: Aging temperature cause component variations, which turn causes system need regular adjustment. Analog systems have more physical parts than digital systems, which reduces reliability makes analog systems more difficult design (component tolerance issues). Upgrades difficult because design hardwired.
Benefits Microcontrollers
Drift eliminated since most functions performed digitally. Upgrades easily made software.
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Part count reduced because microcontroller handle several functions on-chip. Microcontrollers good systems that require high speed precision.
Benefits DSP-Based Control
TMS320C24x includes same advantages microcontroller also offers higher speed, higher resolution, capabilities implement math-intensive algorithms lower system cost. high speed attributable mainly dual Harvard architecture well single-cycle multiplication addition instructions. used data other used program instructions. This saves time because each utilized simultaneously. Traditionally, cost been potential disadvantage solution, this aspect diminished with continuing decline costs. controllers enable enhanced, real-time algorithms well sensorless control. combination reduces number components optimizes design silicon achieve system cost reduction. DSPs capable processing data much faster rates than microcontrollers. example, speed allows estimate motor velocity, task accomplished tachometer analog microcontroller systems. DSP-based controls offer following additional benefits:
Sharp-cutoff notch filters that eliminate narrow-band mechanical resonance. Notch filters remove energy that would otherwise excite resonant modes possibly make system unstable. Diagnostic monitoring achieved fast Fourier transform (FFT) spectrum analysis. observing frequency spectrum mechanical vibrations, failure modes predicted early stages. Adaptive control having speed monitor control system concurrently. dynamic control algorithm adapts itself real time variations system behavior. example, data used tune notch filters track eliminate vibrational modes they vary with system speed, weight, balance, other parameters.
System cost reduction efficient control speed ranges, implying right dimensioning power device circuits High level algorithms from reduced torque ripple, which results lower vibration longer life
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Reduced harmonics using enhanced algorithms meet easier requirements reduce filter costs Remove speed position sensors implementing sensorless algorithms Reduce number look-up tables, which reduces amount memory needed Real-time generation smooth, near-optimal reference profiles move trajectories, which results betterperformance Control power switching inverters generate high-resolution outputs Single chip control system
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Control System
general, control system consists plant process), controller, sensors, actuators. typical control system shown Figure achieve desired output, control system commands regulates plant, thus allowing output behave expected.
Figure Typical Control System
Controller
Actuator
Process/Plant
Sensor
performance reliability microprocessors increase, digital control system approaches have become more attractive designers attempting build their solutions. digital control system block diagram shown Figure
Figure Block Diagram Digital Control System
Digital Controller
Hold
Actuator
Plant
Sensor
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Digital Controller Requirements
following list highlights digital controller requirements.
Calculations powerful enough implement advanced math-intensive control algorithms, such
Fast response events obtain input signals unexpected events secure system Accurate resolution minimize quantization errors; therefore, precise digital control system offered High sampling rate avoid aliasing introduced sampling effects Required peripherals reduce overhead system cost
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Processor Requirements
following list highlights processor requirements.
Strong calculating power advanced math-intensive control algorithms Capability support large word lengths required resolution dynamic range Small interrupt latency fast branch operations capabilities facilitate quick response events, including unexpected events High-MIPS increase range sampling frequency Integrate application-specific peripherals with processor, such timers, converters, generators, communication interfaces. Hence, overhead total system costs reduced.
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TMS320C24x Family Optimal Digital Control System Solution
TMS320C24x, first single-chip solution digital control system market, integrates bit, fixed-point TMS320C2xLP core with several microcontroller peripherals. core itself MIPS cycle time) speed perform useful multiply/accumulate instruction single cycle. TMS320C240 544-word data/program 16Kword program ROM. Although TMS320F240 same amount memory, program Flash type. totally external memory address reach this family 224K words (64K data, program, I/O, global memory). architecture TMS320C240 shown Figure full powerful peripherals include optimized event manager, sets analog-to-digital (A/D) converters on-chip, watchdog timer, serial communication interface (SCI), serial peripheral interface (SPI), four ports.
Figure TMS320C240 Architecture
Data word Program ROM/FLASH Kword Timers Compares Outputs Program Data Buses Dead Band Logic Input Captures 16-Bit Register C2xLP Core 16-Bit Barrel Shifter Multiply 32-Bit Register Shift (0,1,4,-6) 32-Bit 32-Bit Accumulator Shift (0-7) Auxiliary Registers Level Hardware Stack Repeat Count Status Registers Watchdog Timer Converters 10-Bit ADC1 10-Bit ADC2 Four 8-Bit Ports
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event manager module shown Figure Features include three up/down timers nine comparators that create generation capabilities when coupled with flexible waveform generation logic. space-vector state machine implements optimized scheme switching power transistors, yielding longer transistor life span lower power consumption. dead-band generation unit helps protect power transistors. addition, event manager integrates four capture inputs, which serve direct inputs optical-encoder quadrature pulses. all, these features represent state-of-art solution flexible generation system control.
Figure TMS320C240 Event Manager Module
Timer1 Timer compare Compare Unit Compare Unit Compare Unit Timer2
Output Logic Unit
Memory ROM, RAM, Flash
Timer Compare
Output Logic Circuit Output Logic Circuit Output Logic Circuit
Program. Deadband Program. Deadband Program. Deadband
Output Logic Unit
CMP1/PWM1 CMP2/PWM2 CMP3/PWM3 CMP4/PWM4 CMP5/PWM5 CMP6/PWM6 Timer Compare SCMP1/SPWM1
Timer compare Simple Compare Simple Compare Simple Compare Timer3
Output Logic Unit
SCMP2/SPWM2 SCMP3/SPWM3
Timer compare Capture Unit Capture Unit Capture Unit Capture Unit
QEP2
Output Logic Unit
Timer Compare
CAP1/QEP1 CAP2/QEP2 CAP3 CAP4
Inputs ADC2 Inputs
sets 10-bit converters available on-chip. shown Figure each converters provides 8-channel inputs. sample-and-holds allow parallel simultaneous sampling conversion. conversion starts immediately after previous conversion completed. converters begin conversion software instruction, external signal transition device pin, event manager event. conversion time
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Figure TMS320C240 Analog-to-Digital Converter Module
Converter Inputs Multiplexer Sample Hold 10-Bit ADC1 Data Register Level Deep FIFO
Converter Inputs Multiplexer Sample Hold 10-Bit ADC2 Data Register Level Deep FIFO
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Applications
DSPs used servo control actuator that drives read/write head disk drives. Data read from disk very high rate with sampling rates kHz. addition compensator, DSPs implement notch filters attenuate undesirable frequencies that cause mechanical resonance vibrations. servo drives, DSPs used vector control motors. drives have complex control structures because cross coupling three-phase currents. Vector rotation techniques transform three-phase axes into rotating two-phase axes. This two-phase rotation technique greatly simplifies analysis, making equivalent analyzing field-wound motors. UPSs power converters, DSPs used generation well power factor correction harmonic elimination. Advanced mathematical techniques used control firing angles inverters, creating low-harmonic with unity power factors. Three classical motors among existing electric motors market:
with commutators (wound field) Synchronous motor Asynchronous motor
When properly controlled, these classical motors produce constant instantaneous torque (very little torque ripple) operate from pure sine wave supplies. Unlike motors, which levelling even declining each year, motors increasing each year. couple reasons this increase possible: motors cost less than motors and, motors controlled more easily using digital control (especially DSPs). example, brushless permanent magnet synchronous motors (PMSM) include vector control approach which matrix vectors represent control quantities. Using calculation unit included with TMS320C24x provides following advantages:
Full motor torque capability speed Better dynamic behavior
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Higher efficiency each operation point wide speed range Decoupled control torque flux Short term overload capability Four quadrant operation
Sensoring sensorless algorithms also implemented with DSPs. most common sense motor speed shaft incremental encoder. TMS320C240 includes module, quadrature encoder pulse (QEP), that handles situation perfectly, calculating speed direction rotation using only digital inputs 32-bit internal timer register. some applications emphasising efficiency, cost, reliability, mechanics, possible speed, position, Hall (commutation signals) sensor. such situations, necessary information derived from dynamic modelling applications such sliding mode observer Kalman filtering. PMSM applications, Kalman filter used estimation speed rotor position with only measurements motor voltages currents. DSPs also benefit automotive applications ranging from engine/transmission control, active suspension control, adaptive ride control, anti-lock brakes, traction control. performance current electronic engine control power-train control applications improved closed loop control system. system incorporates with sensors, such incylinder pressure sensors, control precise operating status each cylinder every cycle. system performs engine pressure waveform analysis determines best spark timing, firing angles, optimal air/fuel ratios. Closed loop external turbulence, such aging wearing, maintain optimum engine performance fuel efficiency. Vehicle control applications benefit from active suspension that help improve ride performance introducing variable damping ratios into dampers. TMS320C24x also consider body dynamics, such pitch, heave, roll control hydraulic actuators independently dynamically counter external forces attitude changes.
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DSPs perform control algorithms with system parameters adaptively updated achieve road handling ride comfort. design, microcontroller typically incorporated read wheel speed from sensors, calculate skid, control pressure brake cylinders. addition, traction control diagnostics software will demand more processing capability traditional controller.
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Summary
This application report presents controller architecture: controller single chip solutions control applications. TMS320C240 controller combines performance architecture with optimized peripherals microcontroller. With this controller, intelligent control sensorless approach become possible. addition, system cost will reduced reliability entire system will improved.
References
TMS320C24x Controllers, CPU, System, Instruction Set, Reference Set, 1997. TMS320C24x Controllers, Peripheral Library Specific Devices, Reference Set, 1997. Digital Control Applications with TMS320 Family, Irfan Admed, 1991. Solution Permanent magnet Synchronous Motor, application report from Texas Instruments, 1996 Solution Induction Motor, application report from Texas Instruments, 1996
Using TMS320C24X Controller Optimal Digital Control

Authors: Chung Astro Applications Tresna Hidajat Strategic Marketing T

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