Electronic starters and variable speed drives ATV71 the motor control

Training module 3

The motor control
Dominique GENDRON
François MALRAIT

12/28/15 Bertrand Guarinos STIE

ATV71 M3 commande moteur R2 EN

Summary

1


Introduction

ATV71

The ATV71 includes several motor control laws.
These different laws allow the drive to be adapted to a great variety
of induction motors and machines.
This module describes these command law, their application, as
well as their associated functions.

Summary


Summary

ATV71

I.

The motor control laws

II.Motor control menu
III.

Protection against motor o
ver v oltage

IV.Specific applications

Summary


The motor control

I.

ATV71

The motor control laws
•
•
•
•
•

The basics of flux vector control

The voltage flux vector control law SVC U
The current flux vector control law SVC I
The volts/Hertz law (U/f)
The synchronous motor law

II.Motor control menu
III. Protection against motor
over v oltage
IV. Specific applications
Summary


The motor control laws

ATV71

Flux vector control basics

Summary


Flux vector control basics

ATV71

•

The control of an asynchronous motor is made more difficult by the fact that
the electrical parameters (current, voltage, flux) are alternating.

•

Furthermore, flux and torque are dependant upon current.

•

The principal of flux vector control consists in transforming the machine
equations in such a fashion so as to::
– use variables as though the are continuous and no longer alternating,
– simplify the equations in order to decouple the flux and torque variables.

Flux φ r = K1 Id
Torque C = K2 φ s Iq
•

Flux is proportional to the Id component of current.

•

If the flux is constant, the torque is proportional to the Iq component of
current.

Summary


Flux vector control basics
•
•
•

ATV71

Vector control allows the controller to separate the torque producing current and the
flux producing current
This is analogous to a DC motor with separate excitation.
Flux is maintained constant and set at a point to obtain constant torque over the entire
speed range.
Asynchronous
Motor

DC Motor
Φr

Φr

Φs
I inductive
I induced

Φs

Id Flux

Torque

Iq
•
•

The vector control has a speed estimation function that allows the full time

correction of torque and flux.
Thus the performance is much better, for low speed torque, dynamic response,
and speed precision compared to a scalar volts/Hertz law.

Summary


Flux vector control basics

ATV71

 Comparison of U/F and Vector control
Flux Vector Control

U/F Law

Automatic Compensation
(Rs and slip)

Manual Compensation
(U0 voltage at origin)

C/Cn

C/Cn

200 %

100%

F hz
1 3

FrS

F hz
5

10

FrS

Summary


Flux vector control basics

ATV71

 Torque/current relationship
•

The link between current/torque is dependent upon the type and size of the motor as
well as the optimization of the command law.

Example for a motor with Id = 50% of In
Torque
220%

2 In

Typical Values

162%

100%

0%

1.5 In

In

0.5 In
50%

"Id" = Flux
Summary


The motor control laws

ATV71

Voltage vector control law SVC U

Summary


Voltage vector control (CTT=SVC U)

ATV71

•

Voltage vector control is a compromise between performance and robustness.

•

It is compatible with that of the ATV58.

•

It functions only in open loop

 Applications :
•
•
•
•
•
•

Hoisting
General material-handling equipment
Machines requiring low speed torque
Motors in parallel, synchronous with reluctance
Unbalanced loads with the ENA function
Replacement of the ATV58 …

Summary

Voltage Vector Control (CTT=SVC U)

ATV71

 Performance :
•

Good dynamic characteristics

•

Overtorque from 170% to more than 200%, depending upon the motor and
the optimization of the settings (current limit adjustable from 150% to 165%
In of the drive)

•

Nominal torque down to 1Hz, (0,5hz with optimization)

•

Maximum frequency of 500Hz

•

Speed precision =<10 % of slip

•

Speed range 50 (100 with optimization)

•

It can be used with motors in parallel.

Summary


Voltage vector control (CTT=SVC U)

ATV71

 Performance :
•

The speed range in generator mode depends on motor slip

•

Speed feedback by sensor allows the improvement of static speed precision
and insures sway detection.

•

Band pass:

•

– 0.37 to 2.2kW

15Hz

– 3 to 7.5kW

12Hz

– 7.5 to 75kW

10Hz

– 280 kW
– 500 kW

4 Hz
2 Hz.

This performance is guaranteed for a motor of the same size than the motor
and up to one size below.

Summary


Voltage vector control (CTT=SVC U)

Flux
Calculation

Φ ref

ATV71

Id ref

Current
Sensors
Voltage
Calculation

Ω cons

Speed
Ramp

+
-

Speed
Regulation

Id

Ω est

Iq ref

Current
Regulation

Va

Vd, Vq

(d,q)
Vb

(a,b,c) Vc

PWM
Motor

Current/torque
Limitation

+

Integration

Θs

+

Iq

Speed
Estimate

Slip
Compensation

Id Iq

Current
measurement
(d,q)  (a,b,c)

Summary


Voltage vector control (CTT=SVC U)

ATV71

 Torque curves (11kW 400V motor quadrant)

Summary


Voltage vector control(CTT=SVC U)

ATV71

 Torque curves (11kW 400V motor quadrant 0-5Hz)

Summary


The motor control laws

ATV71

Current vector control law SVC I and FVC

Summary


Current vector control

ATV71

•

The current vector control law allows the drive to attain better static and dynamic performance for
torque and speed.

•

Requires a good understanding of the motor characteristics

•

It is compatible with the ATV58F

•

It functions in open or closed loop

 Applications :
•

•
•
•
•

Vertical hoisting movements
High process rate machines
Rapid material-handling
Positioning
Base law for the torque control function

Summary


Current vector control

ATV71

 Performance :
•

Very good dynamic speed and torque characteristics

•

Overtorque from 170% to more than 200%, depending on the motor and the
optimization of the settings (current limit adjustable from 150% to 165% In drive)

•

Maximum frequency 500Hz

•

The motor nameplate information and TUN are required.

•

Flux feedback permits the improvement of braking performance without a braking
resistor.

Summary


Current vector control (CTT=SVC I)

ATV71

 Performance in open loop
•

The general performance is comparable to voltage vector control.

•

Always with better torque precision and better defluxed braking.

•

Can be used with motors in parallel if the motors are identical

•

Nominal torque down to 1Hz, (0,5hz with optimization)

•

Speed precision =<10 % of slip

•

Speed range 50 (100 with optimization)

•

Torque regulation mode :
– Precision 15%
– Up to +/-300% of nominal torque (Cn)

Summary


Current vector control (CTT=SVC I)

ATV71

 Open loop

Φ ref

Estimate of
magnetizing
inductance

Flux
Calculation

Id ref
Voltage
calculation

Id
Ω cons

Speed
Ramp

+
-

Speed
Regulation

Id

Ω est

Current
sensors

Iq ref

Current
regulation

Va

Vd, Vq

(d,q)
Vb

(a,b,c) Vc

PWM
Motor

Current/torque
Limit

+

Integration

Θs

+

Iq

Speed
Estimation

Slip
Compensation

Id Iq

current
measruement
(d,q)  (a,b,c)

Summary


Current vector control (CTT=SVC I)

ATV71

 Torque curves in open loop (motor quadrant 11kW)

Summary


Current vector control (CTT=SVC I)

ATV71

 Torque curves in open loop (motor quadrant 11kW 0-5Hz)

Summary


Current vector control (CTT=FVC)

ATV71

 Performance in closed loop
•

Torque at 0 speed is available in motoring or generating quadrant

•

Speed precision is 0,02%* of the nominal speed

•

Speed range 1000*

•

Band pass:
– 0.37 to 2.2kW

50Hz

– 3 to 7.5kW

30Hz

– 7.5 to 75kW

15Hz

– 280 kW

8 Hz

– 500 kW

5 Hz

•

Cannot be used with motors in parallel.

•

Torque regulation mode :
– Precision 5%
– Up to +/-300% of nominal torque (Cn)

* Indicative values dependent upon the resolution of the encoder
Summary


Current vector control (CTT=FVC)

ATV71

 Closed loop

Φ ref

Estimate of
magnetizing
inductance

Flux
Calculation

Id ref
Voltage
Calculation

Id
Ω cons

Speed
Ramp

+
-

Iq ref

Speed
Regulation

Id

Current
sensors

Current
Regulation

Va

Vd, Vq

(d,q)
Vb

(a,b,c) Vc

PWM
Motor

Encoder

Current/torque
Limitation

+

Ω est

Integration

Θs

+

Speed
Measure

Iq

Slip
Compensation

Id Iq

current
measurments
(d,q)  (a,b,c)

Summary