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DSP-BASEDELECTROMECHANICAL
MOTION CONTROL
Subject Overview
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 2
Course Overview
Course name: DSP-BASED ELECTROMECHANICAL MOTION
Credit points: 2 (8Wks, 32Hrs)
Pre-requisites: Electrical MachineryPower electronicsMotion controlDSP theory and application (TMS320LF2407)
Instructor: SUN Dan
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 3
Textbook and references
Textbook: DSP-Based Electromechanical Motion ControlAmazon.comwww.ti.com
Referenceswww.ti.comwww.freescale.com…
Some Chinese textbooks…
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 4
Course Content
1. DSP in Motor Control 2. DSP TI C2000 (Code Composer Studio)3. DSP Solution for BLDC motors4. Clarke’s and Park’s Transformation5. SVPWM Implementation6. DSP Solution for AC Induction Motors7. DSP Solution for PMSM
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 5
English video - for the beginner
Video:http://www.galilmc.com/training/webconf.html
"Motion Controller Demonstration" In this 15-minute video, Jacob Tal demonstrates tuning and programming motion using a Galil DMC motion controller, WSDK servo design software and a servo motor with encoder.
Tuning:"Tuning Servo Systems for Optimum Performance" Adjustment of PID filter parameters for fast and stable performance of servo systems
DSP-BASEDELECTROMECHANICAL
MOTION CONTROL
DSP in Motor Control Overview
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 7
DSP in Motor Control
The Motor Control industry is a strong aggressive sector. Propulsion systemHome appliance…
Each industry to remain competitive must reduce costs but also has to answer to power consumption reduction and EMI radiation reduction issues imposed by governments and power plant lobbies.
The results of these constraining factors are the need of enhanced algorithms.
DSP technology allows to achieve both, a high level of performance as well as a system cost reduction.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 8
Motor Control Trend - analog controller
Traditionally motor control was designed with analogcomponents,
they are easy to design and can be implemented with relatively inexpensive components.
However, there are several drawbacks with analog systems. Aging and temperature can bring about component variation causing the system to need regular adjustment, as the parts count increase the reliability of the system decreases . Analog components raise tolerance issues and upgrades are difficult as the design is hardwired.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 9
Motor Control Trend - digital controller
Digital systems offer improvements over analog designs.
Drift is eliminated since most functions are performed digitally,
upgrades can easily be made in software
and part count is also reduced since digital systems can handle several functions on chip.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 10
Motor Control Trend - DSP
DSPs go on further to provide high speed, high resolution and sensorless algorithms in order to reduce system costs.
Providing a more precise control means performing morecalculations, the use of some 1-cycle multiplication & addition instructions included in a DSP speeds-up calculations.
Generally fixed point DSPs are preferred for motor control for two reasons:
Firstly, fixed point DSPs cost much less than the floating point DSPs. Secondly, for most application a dynamic range of 16 bits is enough. If and when needed, the dynamic range can be increased in a fixed-point processor by doing floating-point calculations in software.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 11
Benefits of DSP in motor control
The performances of an electric motor, especially AC motor, are strongly dependent on its control. DSP controllers enable enhanced real time algorithms as well as sensorless control. The combination of both allows to reduce the number of components and to optimize the design of silicon, to achieve a system cost reduction.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 12
Motor Control Trend - Summary
Motor Control Migrate from Analog to Digital Control
Increased ReliabilityEfficiency FlexibilityIntegration
Reduced Cost
Improvement
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 13
Motor Control Trend - Summary (cont.)
The Benefits of Advanced Algorithms and PeripheralsFrom brush to brushless motors, sensorless control & field oriented control On-chip peripherals, analog and flash enabling furtherintegration and cost reductionUpgradeable, flexible, robust platform designsFast and precise PWM switching of the converterFast, accurate feedback of motor control parameters(e.g. currents, voltages, speed, temperature, etc.)Eliminate costly hardware with software routines
Cost, cost, cost...
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 14
A Large Range of Applications
Typical end equipment applications for a fixed point DSP controller with an advanced control are:
Appliances (washers, blowers, compressors) HVAC (heating, ventilation and air conditioning) Industrial servo drives (Motion control, Power supply inverters,Robotics) Automotive control (electric vehicles, Power steerings, Anti-lock brakes, Suspension controls).
DSP in Motor Control
Electric Motors Review
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 16
Classification of Electric Motors
Electric motors convert electrical energy into mechanical motion and are broadly classified into two different categories:
DC (Direct Current) and AC (Alternating Current).
Within these categories are numerous types, each offering unique abilities that suit them well for specific applications.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 17
Classification of Electric Motors
In most cases, regardless of type, electric motors consist of a stator (stationary field) and a rotor (the rotating field or armature) and operate through the interaction of magnetic flux and electric current to produce rotational speed and torque.
These motors, when properly controlled, produce constant instantaneous torque (very little torque ripple) and operate from pure DC or AC sinewave supplies.
Whether rotating or linear, motors enable us to move people and machines. They impact every aspect of our daily lives.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 18
Classification of Electric Motors
ElectricMotor types
ElectricMotor types
DCDCACAC
AsynchronousAsynchronousSynchronousSynchronous
InductionInduction
StepperStepperPMSMPMSMPM BLDCPM BLDC Switched Rel.Switched Rel.Squirrel cageSquirrel cage Wound rotorWound rotor
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 19
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 20
Classification of Electric Motors
Motor Classification:Direct Current Motors (DC)Alternating Current Motors (AC)
Asynchronous Induction Motor (ACI)Permanent Magnet Synchronous Motor (PMSM)Synchronous Brushless DC Motor (BLDC)
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 21
DC MotorsThis is a PM DC motor, the stator is the stationary outside part of a motor; the rotoris the inner part which rotates. In the motor animations, red represents a magnet or winding with a north polarization, while green represents a magnet or winding with a south polariztion.
The stator of the dc motor is composed of two or more permanent magnet pole peices. The rotor is composed of windings which are connected to a mechanical commutator. In this case the rotor has three pole pairs.The opposite polarities of the energized winding and the stator magnet attract and the rotor will rotate until it is aligned with the stator.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 22
DC Motors
Just as the rotor reaches alignment, the brushes move across the commutatorcontacts and energize the next winding. In the animation the commutator contacts are brown and the brushes are dark grey.
A yellow spark shows when the brushes switch to the next winding.Notice that the comutator is staggered from the rotor poles. If the connections of a dc motor are reversed the motor will change directions. Though it will not always work as well in both directions.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 23
DC Motor Drive
DC motors are controlled by an H-bridge consisting of four power switches. They enable you to adjust the motor voltage and polarity using the Pulse Width Modulation (PWM) technique. Thus speed and direction of the motor can be controlled.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 24
Key Characteristics of DC Motors
High construction complexity, Low reliability (brush wear), Low efficiency, Terrible EMI (brushes create sparks and ozone), Driven by Rheostat, H-bridge or Chopper controllers, Easy to drive, even sensorless, Lowest total system cost for basic motion
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 25
BLDC MotorsBrushless DC motors are refered to by many aliases: brushless permanent magnet motor, permanent magnet AC motors, permanent magnet synchronous motors ect. A brushless DC motor does not directly operate off a DC voltage source. However, the basic principle of operation is similar to a DC motor.
A brushless DC motor has a rotor with permanent magnetsand a stator with windings. It is essentially a DC motor turned inside out. The brushes and commutator have been eliminated and the windings are connected to the control electronics. The control electronics replace the function of the commutator and energize the proper winding.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 26
BLDC Motors
As shown in the animation the winding are energized in a pattern which rotates around the stator.
There are no sparks, which is one advantage of the BLDC motor.
The brushes of a DC motor have several limitations; brush life, brush residue, maximum speed, and electrical noise. BLDC motors are potentially cleaner, faster, more efficient, less noisy and more reliable.
However, BLDC motors require electronic control.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 27
BLDC Motor Drive
The BLDC motor is driven by rectangular voltage strokescoupled with the given rotor position. The generated stator flux interacts with the rotor flux, which is generated by a rotor magnet, defines the torque and thus the speed of the motor. The voltage strokes must be properly applied to the two phases of the three-phase winding system so that the angle between the stator flux and the rotor flux is kept close to 90°to get the maximum generated torque. Due to this fact, the motor requires electronic control for proper operation.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 28
BLDC Motor Drive
In adjustable speed applications, AC motors are powered by inverters.
The inverter converts DC power to AC power at the required frequency and amplitude.
The inverter consists of three half-bridge units where the upper and lower switch are controlled complimentarily.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 29
BLDC Motor Drive
As the power device's turn-off time is longer than its turn-on time, some dead-time must be inserted between the turn-off of one transistor of the half-bridge and turn-on of it's complementary device.
The output voltage is mostly created by a pulse width modulation (PWM) technique.
The 3-phase voltage waves are shifted 1200 to each other and thus a 3-phase motor can be supplied.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 30
3 – Phase Voltage Source Inverter
PowerSwitchingDevices
3-phase outputs to motor terminals
+
−
Upper & lowerdevices can notbe turned on simultaneously(dead band)
Six PWM signalsto control Power Switches
DC - Voltage
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 31
Key Characteristics of BLDC MotorsReally a multi-phase AC motor, but can control it like a DC motor using trick, Like a DC motor turned inside out, commutation done on windings, Medium construction complexity, multiple fields, delicate magnets, High reliability (no brush wear), even at very high achievable speeds, High efficiency, Low EMI, Driven by multi-phase Inverter controllers, Sensorless speed control possible, Higher total system cost than for DC motors,
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 32
Applications of BLDC MotorsPC fans, Ceiling fans, Blowers, Washing machines, Electrical Power Steering, Industrial drive, Servo drives, Electric vehicle traction drive, Automotive applications, Refrigerator, AirConditioning, Fan
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 33
Induction Motors
The stator windings of an induction motor are distributed around the stator to produce a roughly sinusoidal distribution. When three phase AC voltages are applied to the stator windings, a rotating magnetic field is produced.
The rotor of an induction motor also consists of windings or more often a copper squirrel cage imbeded within iron laminates. (Only the iron laminates are shown) An electric current is induced in the rotor bars which also produce a magnetic field.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 34
Induction Motors
The rotating magnetic field of the stator dragsthe rotor around. The rotor does not quite keep up with the rotating magnetic field of the stator. It falls behind or slips as the field rotates.
In this animation, for every time the magnetic field rotates, the rotor only makes three forths of a turn. If you follow one of the bright green or red rotor teeth with the mouse, you will notice it change color as it falls behind the rotating field.
The slip has been greatly exaggerated to enable visualization of this concept. A real induction motor only slips a few percent.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 35
Induction Motor
The most common type of asynchronous motor (induction motor ) uses a squirrel cage type rotor.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 36
Induction Motor Drives - Inverter
PowerSwitchingDevices
3-phase outputs to motor terminals
+
−
Upper & lowerdevices can notbe turned on simultaneously(dead band)
Six PWM signalsto control Power Switches
DC - Voltage
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 37
Key Characteristics of Induction Motor Medium construction complexity, multiple fields on stator, cage on rotor High reliability (no brush wear), even at very high achievable speeds Medium efficiency at low speed, high efficiency at high speed Driven by multi-phase Inverter controllers Motor EMI good but … terrible EMI from Inverter Sensorless speed control possible Low cost per horsepower, though higher than for 1-ph AC induction motor Higher start torque than for 1-ph, easy to reverse motor Inverter ‘shoot-through’ possible, requires ‘dead-time’ circuits & compensation
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 38
Applications of Induction Motor
Washing machines, Compressors, Air conditioning units, Pumps, Simple industrial drives, Electric cars, Industrial machines (most popular in world)
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 39
PMSM
The PM Synchronous motor is a rotating electric machine where the stator is a classic three phase stator like that of an induction motor and the rotor has surface-mounted (or other types) permanent magnets.
In this respect, the PM Synchronous motor is equivalent to an induction motor where the air gap magnetic field is produced by a permanent magnet. The use of a permanent magnet to generate a substantial air gap magnetic flux makes it possible to design highly efficient PM motors.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 40
PMSM
A PM Synchronous motor is driven by sine wave voltage coupled with the given rotor position. The generated stator flux together with the rotor flux, which is generated by a rotor magnet, defines the torque, and thus speed, of the motor.
The sine wave voltage output have to be applied to the 3-phase winding system in a way that angle between the stator flux and the rotor flux is kept close to 90°to get the maximum generated torque. To meet this criterion, the motor requires electronic control for proper operation.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 41
PMSM Drive
For a common 3-phase PM Synchronous motor, a standard 3-phase power stage is used. The same power stage is used for AC induction and BLDC motors. The power stage utilizes six power transistors with independent switching. The power transistors are switched in the complementarymode. The sine wave output is generated using a PWM technique.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 42
Key Characteristics of PMSMLike a multiphase AC motor, but contains magnets at rotor Medium construction complexity, multiple fields, delicate magnets High reliability (no brush wear), even at very high achievable speeds High efficiency Low EMI Driven by multi-phase Inverter controllers Sensorless speed control possible Higher total system cost than for DC motors Smooth rotation - without torque rippleAppropriate for position control
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 43
Full Step Stepper Motor
This animation demonstrates the principle for a stepper motor using full step commutation. The rotor of a permanent magnet stepper motor consists of permanent magnets and the stator has two pairs of windings.Just as the rotor aligns with one of the stator poles, the second phase is energized.
The two phases alternate on and off and also reverse polarity. There are four steps. One phase lags the other phase by one step.This is equivalent to one forth of an electrical cycle or 90°
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 44
Full Step Stepper Motor
These are formed using a single magnet mounted inline with the rotor axis and two pole pieces with many teeth. The teeth are staggered to produce many poles. The stator poles of a real stepper motor also has many teeth. The teeth are arranged so that the two phases are still 90°out of phase.
This stepper motor is very simplified. The rotor of a real stepper motor usually has many poles. The animation has only ten poles, however a real stepper motor might have a hundred.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 45
Half Step Stepper Motor
This animation shows the stepping patternfor a half-step stepper motor. The commutation sequence for a half-step stepper motor has eight steps instead of four.
The main difference is that the second phase is turned on before the first phase is turned off. Thus, sometimes both phases are energized at the same time. During the half-steps the rotor is held in between the two full-step positions.A half-step motor has twice the resolution of a full step motor. It is very popular for this reason.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 46
Switched Reluctance Motors
A switched reluctance or variable reluctance motor does not contain any permanent magnets. The stator is similar to a brushless DC motor.
However, the rotor consists only of iron laminates. The iron rotor is attracted to the energized stator pole. The polarity of the stator pole does not matter. Torque is produced as a result of the attraction between the electromagnet and the iron rotor.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 47
Switched Reluctance Motors
The rotor forms a magnetic circuit with the energized stator pole. The reluctance of a magnetic circuit is the magnetic equivilent to the resistance of a electric circuit. The reluctance of the magnetic circuit decreases as the rotor aligns with the stator pole. When the rotor is inline with the stator the gap between the rotor and stator is very small. At this point the reluctance is at a minimum. This is where the name “Switched Reluctance” comes from.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 48
Switched Reluctance Motors
The inductance of the energized winding also varies as the rotor rotates. When the rotor is out of alignment, the inductance is very low, and the current will increase rapidly. When the rotor is aligned with the stator, the inductance will be very large and the slope decreases. This is one of the difficulties in driving a switched reluctancemotor.
DSP-BASEDELECTROMECHANICAL
MOTION CONTROL
Motor Control Strategies Review
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 50
Motor Control Strategies
There are several ways to control a motor in torque, speed or position; they can be generally categorized into two groups: the scalarand the vector control.
Scale control: V/Hz (VVVF) control
Vector control:FOCDTC…
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 51
AC Induction motor control requirements
InputTypically speed
ControlScalar ControlDirect Field Oriented ControlDirect Torque Control
FeedbackNone for open loop V/Hz (VVVF)Speed and current for FOCCurrent for simple DTC
Driver3-phase inverter for 3-phase ACI motor
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 52
Scalar Control of Induction Motor- OverviewScalar control (or V/Hz control) is a simple technique to control speed of induction motor.
The steady-state model of induction motor is mainly used to derive the technique, so transient performance is not possible.
Air-gap flux is approximately maintained constant over different speeds.
The system has no current loop.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 53
Scalar Control Scheme (V/Hz )
Simple to implement: All you need is three sine waves source feeding the motorPosition information not required (optional).Doesn’t deliver good dynamic performance.Torque delivery not optimized for all speeds
ω* PI3-
PhaseInverter
PWMCommand
Σ+PWM1PWM2PWM3
PWM5PWM4
PWM6
V
fV/f profile
Speed scaling
Speed calculator
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 54
V/Hz Control of Induction Motor
Simplified steady-state equivalent circuit of ACI
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 55
V/Hz Control of 3-ph Induction Motor
Voltage versus frequency in V/Hz control
Simple to implement: All you need is three sine waves feeding the ACINo position information needed.Doesn’t deliver good dynamic performance.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 56
Relationship Between Torque and Horsepower Over Speed
Torque vs. speed curve illustrating constant torque and constant horsepower regions.
Horsepower = Torque x Speed
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 57
Limitations of the Scalar V/Hz Technique
At or near nominal speed:Stator voltage drop negligible: (Vm = V),At low speed: Rs is no longer negligible: (Vm < V), A large portion of energy is now wasted.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 58
Limitations of the Scalar V/Hz TechniqueACCELERATION DECELERATION
High peak current:In V/Hz, the rotor flux and current are not controlled: Current reachesvalues based on circuit parameters.Poor response time:A solution to minimize these current overshoots is to decrease theperformances of the speed regulator.Slow speed regulator → poor mechanical behavior.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 59
Three Phase Inverter (SPWM)
Three-phase PWM waveforms
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 60
Space Vector PWM (SVPWM)
SVPWM is Used to create the AC waveforms in the motor but Different than SPWM.
SPWM treat each phase individually.2 PWM channels per phase
SVPWM treats the inverter as ONE unit!!ALL 6 switches affected.
SPWM control the phase voltages.120° offsets between A,B and C
SVPWM controls the Voltage Vector.
15% higher effective motor voltage30% less switching losses30% reduced EMI
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 61
Space Vector PWM (SVPWM)
The inverter can be driven to 8 states.
- 6 voltage vectors
- 2 null vectors
1 = Top Switch is on0 = Bottom Switch is on
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 62
Summary of ACI V/Hz Control
Scalar control (or V/Hz control) is a simple technique to control speed of induction motor.
The steady-state model of induction motor is mainly used to derive the technique, so transient performance is not possible.
Air-gap flux is approximately maintained constant over different speeds.
The system has no current loops.
DSP-BASEDELECTROMECHANICAL
MOTION CONTROL
Direct Field Oriented Control of 3-PhInduction Motor
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 64
Stationary and Rotating Reference Frames
Three phase stationary reference frame Two phase orthogonal stationary reference frameRotating Orthogonal Reference Frame
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 65
FOC OverviewFOC is a control strategy for 3-ph AC motors. The approach is imitating the DC motors’ operation.
All controlled variables are transformed to DC instead of AC via Park transformation.
Goal: torque and flux are independently controlled.
Direct FOC: rotor flux angle is directly computed from flux estimation or measurement.Indirect FOC: rotor flux angle is indirectly computed from available speed and slip computation (with lqr=0 condition).
FOC will be possible with system information: currents, voltages, flux and speed.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 66
DC Motor-Elementary Construction
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 67
DC Motor - Operation Principle
torque and flux are independently controlled.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 68
3-ph Induction Motor
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 69
How λqr could be zero ?
For λqr = 0, d-axis must align with rotor flux vector.
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 70
FOC control scheme
Some key mathematical components are required!
ωPID
d,q
a,b,c
3-Phase
Inverter
SpaceVectorPWM
ΣΣVq
Vd
VQ
VD
iaib
Iq
Id
IQ
ID
IQ
ID
+
+
+
ωr
qr
ic†
ia + ib + ic = 0
PWM1
D,Q
d,q
Park T Clarke T
Σ
qr
PWM2PWM3
PWM5PWM4
PWM6
Field Weakening Controller
Speed Calculator
Inverse Park
D,Q
d,qPID
PID
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 71
Park transform (1929):
(Vs): voltage vector applied to motor stator (index s)
⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡=
3
2
1
)(
S
s
s
S
vvv
V
Park transform is a referential change
[ ] [ ]⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡=
⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
=⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎥⎥⎥⎥⎥⎥
⎦
⎤
⎢⎢⎢⎢⎢⎢
⎣
⎡
−−−
−−−
−
=⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
−
3
2
11
3
2
1
3
2
1
)( and .)(
1 )3
4sin( )3
4cos(
1 )3
2sin( )3
2cos(
1 sin cos
S
S
s
S
So
Sq
sd
so
sq
sd
S
S
S
s
So
Sq
sd
SS
SS
SS
s
s
s
vvv
P
v
vv
v
vv
Pvvv
v
vv
vvv
θθ
πθπθ
πθπθ
θθ
1sv
3sv
2sv
sdv
sqv
0=sov
tSS ωθ =
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 72
Park Transform key components
1sv
3sv
2sv
sdv
sqv
0=sov
tSS ωθ =
(vsd, vsq, vso) are called the Park coordinatesvsd: direct Park componentvsq: squaring Park componentvso: homo-polar Park componentVso is null for a three-phases balanced systemEach pair of components is perpendicular to each other
⎪⎪
⎩
⎪⎪
⎨
⎧
==
==++
0.0.
0.system) balanced phases-(tri 0321
SoSq
SoSd
SqSd
SSS
vvvv
vvvvv
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 73
Clarke – TransformationTransform is usually split into CLARKE transform and one rotationCLARKE converts balanced three phase quantities into balanced two phase orthogonal quantities
3.2 12
1
vvv
vv+
=
=
β
α
⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡⋅
−=
βα
θθθθ
vv
SSSS
qvdv
)cos()sin()sin()cos(
Clarke
+Rotation
tSS ωθ =
v1= vα
v3
v2vβ vd
vq
Park Transform
DSP-BASEDELECTROMECHANICAL
MOTION CONTROL
C2000 - Digital Motor Control Library Overview
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 75
Digital Motor Control Library (DMC-Lib)
The DMC-Library is a collection of most commonly used algorithms and function blocks for motor control systems
For every algorithm and function:Essential theoretical background information
Data types for input/output parameters with numerical range and precision
Function prototypes and calling conventions
code size (program and data memory)
Build Level based code examples
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 76
Digital Motor Control Library (DMC-Lib)
The DMC-Lib containsPID regulators,Clarke transformers,Park transformers,Ramp generators,Sine generators,Space Vector generators,Impulse generators,
and more…
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 77
TI Motor Control Solution
“C2000 - Digital Motor Control Library (DMC)” :
Single Phase ACI Motor Control Using Constant V/Hz3-Phase ACI Motor Constant V/Hz Control3-Phase ACI Motor Field Oriented Control3-Phase Sensored Field Oriented Control (PMSM)3-Phase Sensorless Field Oriented Control (PMSM)3-Phase Sensored Trapezoidal Control (BLDC)3-Phase Sensorless Trapezoidal Control (BLDC)
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 78
Example: Sensorless Solution for PMSM
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 79
H/W System Block Diagram
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 80
Motor Control System Components From TI
2008-9-5SUN Dan
College of Electrical Engineering, Zhejiang University 81
The end