Hitachi AN072302-1 User's Guide

SJ300 Series Inverter  Application Note:  Optimizing Vector Control

Hitachi America, Ltd.

AN072302-1

Please refer also to the SJ300 Inverter 

Instruction Manual and the SJ-FB Option 

Board Instruction Manual

Application Note for Vector Control with the SJ300 Inverter

Contents

[1] Overview

[2] How to Tune Each Parameter

(2-1) Tuning target of each parameter (2-2) SLV Control block diagram (2-3) V2 Control block diagram (2-4) Standard motor parameter settings for SJ300 (400V class EU version) series inverter (2-5) Example of tuning effects (SLV mode)

[3] Positioning Under ASR mode (Orientation Function)

(3-1) Orientation Function (3-2) Example of positioning under speed control mode (ASR) on SJ300 with SJ-FB

(3-2-1) Example of wiring (3-2-2) Example of parameter settings (3-2-3) Timing chart

[4] APR Control

(4-1) Example of parameter settings (4-2) How to adjust control parameters for APR control

[5] Master Slave Control

(5-1) Example of parameter settings for Master-Slave control (5-2) How many slaves can be connected?

(5-2-1) Parallel connection (5-2-2) Series connection

(5-3) Explanation of each P parameter (5-4) Explanation of each output related to V2 control

Appendix A Calculation of total inertia (reflected to the motor shaft)

(A-1) Ventilation Fan (A-2) Truck (A-3) Conveyer

Appendix B Calculation of load inertia

(B-1) A column (B-2) A cylinder (B-3) A rectangular solid (B-4) A Cone (B-5) Wind up (vertical linear motion) (B-6) Horizontal linear motion

This document is a guideline for optimizing motor/inverter performance in vector mode through parameter adjustments. Please note that actual performance of the motor depends on a combination of many parameters, and is difficult to describe concisely. Trial & error is the customary means to achieve good motor performance. Therefore please regard this information as just a guide only.

This document only shows technical issues related to vector control. Please refer to the SJ300 Inverter and SJ-FB manuals for detailed information for installation and operation.

[1] Overview

ASR

Slip reference

Frequency

q axis current

Slip reference

Speed

Change over

Stability

1/s

d-axis current

d-axis

q-axis

Estimation of

calculation of

Output

Estimation of

This engineering note applies when using SLV , 0-SLV and V2 (closed loop) control. It is often difficult to get optimized motor performance because many parameters interact. Please refer to this document for getting a rough idea how to achieve good motor performance with above control modes. Please also note that

the performance WILL NOT BE like a servo drive even in the case of V2 mode.

There are 3 basic modes with which you can get high torque performance with the SJ300 inverter:

(1) SLV control (No SJ-FB is used)

High motor torque performance with open loop can be obtained in the low frequency range (~0.5Hz). Please refer to a standard SLV block diagram in Fig 1 (section 2-2).

[H***] parameters are mainly adjusted for the control.

(2) 0-SLV control (No SJ-FB is used)

High torque performance can be obtained at around 0Hz. This does NOT mean the motor shaft will be at a standstill. The motor rotates slightly to generate motor torque, since this is not a servo drive. Depending on the application and tuning, you may be able to get full torque with the motor at standstill. This control algorithm is different from SLV control.

[H***] parameters are mainly adjusted for the control.

Œ Frequency control block portion

reference

ωr*

(PI)

reference

ωr^

Iq*

estimation

of control

• Voltage control block portion

Magnetizing current

id*

Torque current

iq*

reference

id**

ωs*

at 0Hz

q-axis flux

∆E

ACR

∆V

Output frequency

control

Voltage Vector

Motor torque

Output phase

Flux

Vd* Vq*

voltage

Feedback current

(3) V2 control (SJ-FB is used)

High torque and stable, accurate motor performance can be achieved with the SJ300 in vector mode. A motor encoder and a feedback option card for SJ300 (SJ-FB) are needed to use this control mode. There are two regulation modes within the V2 control mode: ASR mode and APR mode .

Œ ASR mode : Inverter is controlled by speed command input (digitally set, analog input, or RS485)

• APR mode : Inverter is controlled by pulse train input signal

[H***] and [P***] parameters are adjusted for achieving good motor control.

A suitable mode should be selected depending on the application.

[Difference between each control]

Ø Control performance

Item SLV mode V2 mode Speed linearity <1 % <0.01 % Speed fluctuation <1 % <0.01 % Control range 1 : 50 1 : 100

Speed response 15 rad/s 60 rad/s Torque control range 1 : 50 1 : 100 Torque response 50 rad/s 500 rad/s

s Note: These are representative values only.

Percentages are relative to base speed

Ø Torque performance at low speed

Item SLV control 0-SLV control V2 control Down sized motor 150% or more 150% or more 150% or more Same kW motor 100% or more 100% or more 100% or more

s These are guaranteed minimum values with a Hitachi standard induction motor. Actual capability is greater.

Ø Torque performance at 0Hz

Item 0-SLV control V2 control Down-sized motor 150% or more

with a small slip

Same kW motor 100% or more

with a small slip

150% or more with standstill 100% or more with standstill

s This has been confirmed using Hitachi standard induction motor and J2 motor (for V2 control).

[2] How to tune each parameter

Equivalent circuit of one leg of

Small

(2-1) Tuning target of each parameter

There are many parameters, which influence the motor performance in SLV, 0-SLV & V2 control modes. In some cases auto tuning is not fully sufficient to get the best motor performance because there are various kinds of motors in the world. It is sometimes necessary to adjust by hand after the auto tuning.

Generally the performance of the motor can be determined from two criteria:

Ø Torque performance at low speed Ø Speed response against target speed

Table 1 shows main parameters that influence the motor performance inSLV mode. The concept is the same in 0-SLV and V2 modes as well.

Table 1. Explanation of parameters related to motor performance in SLV mode

Code Function Remarks H001 Auto tuning mode This determines the method of auto tuning.

00 (NOR) : Auto tuning invalid

R1 L

the motor winding

01 (NRT) : Auto tuning with motor at standstill 02 (AUT) : Auto tuning with motor rotation

Auto tuning determines the following motor constants automatically. (See left figure as well.)

Ÿ R1 (primary resistance) Ÿ R2 (secondary resistance) Ÿ L (leakage inductance) Ÿ Io (magnetizing current at base frequency) Ÿ J (total load inertia)

Normally better motor performance can be obtained by auto tuning with motor rotation with an actual load on the motor. But if the system does not allow rotating the motor, like a lift application for example, auto tuning with motor at standstill can be used.

H002 Motor constant selection This determines which set of motor parameters is used by the drive.

00 : Motor parameters for a Hitachi standard motor

(Uses [H020] ~ [H024] )

01 : Use auto tuning data

(Uses [H030] ~ [H034] )

02 : Use auto tuning data with On-line auto tuning

On-line auto tuning occurs every time the inverter stops. It measures R1 and R2, the main values that may change due to a motor temperature change. The tuning period is roughly 5 seconds maximum, and if the RUN command is given during

the tuning routine, the inverter will start and tuning is aborted. H003 Motor kW This sets the motor kW, not a kW of an inverter. H004 Motor poles H005

H006 Motor stability control factor This should be adjusted in case of motor instability.

H020 / H030 Primary resistance of the

H021 / H031 Secondary resistance of the

Speed response factor K

motor R1 [Ω ]

motor R2 [Ω ]

Torque

ideal

Big R2

Controls the speed response

Large K à Quick response (Too high a value can cause instability.)

Ÿ Small K à Slow but stable response

Value is also dependent on Proportional gain (P-gain : [H050])

and Integration gain (I-gain : [H051]). ( K = f(Kp, Ki) ).

Increase / decrease depends on the situation.

Influences mainly the torque at low speed.

Ÿ Large R1 à Higher torque (Too high R1 à Over magnetizing)

Ÿ Small R1 à Smaller torque

Influence mainly on the speed change ratio (= slip compensation)

Ÿ Large R2 à Increase speed change ratio

(= Actual speed becomes faster than a target speed.)

Ÿ Small R2 à Decrease speed change ratio

(= Actual speed becomes slower than a target speed.)

Speed

Code Function Remarks

See Remarks for H050

H022 / H032 Leakage inductance of the

motor L [mH]

H023 / H033 Magnetizing current of the

motor Io [A]

L does not influence control much compared to other

parameters, however a suitable value is recommended to be set.

Influences mainly the torque at low speed.

Ÿ Large Io à Bigger torque (Too big Io à Over magnetizing)

Ÿ Small I

à Smaller torque

H024 / H034 Total inertia J [kgm2] Influences mainly speed and torque response performance

This should be the total inertia (Σ J) on the motor shaft,

including the inertia of the rotor of the motor and the load. See

table 2 for information on how to tune in each case.

See appendix A for calculation of the total inertia.

H050 Proportional gain under

PI control mode (Kp)

(% based on [H005])

H051 Integration gain under

PI control mode (K

)

(% based on [H005])

Fine tuning of proportional portion of speed response factor.

Ÿ Large Kp àQuick response (Too high Kp can cause instability.)

Ÿ Small K

à Slow but stable response

Fine tuning of Ki portion of speed response factor.

Ÿ Large Ki à Quick response (Too high Ki can cause instability.)

Ÿ Small K

à Slow but stable response

H052 Proportional gain under

P control mode (Kp)

(% based on [H005]) F002 Acceleration time F003 Deceleration time

Acc and Dec time influence the response. Even if optimized tuning parameter values are set, actual motor speed will change according to the set ramp time.

If a quick response is required, the ramps should be set as fast as

possible. Or, use LAC (LAD cancellation) to make the ramp invalid. A044 Control mode Control mode should be set to 03 (SLV), 04 (0-SLV) or 05 (V2). A045 Output gain (Vgain ) Output gain scales the duty cycle of PWM output, regardless of

the input voltage of the inverter.

Decreasing output gain can solve the problem of motor instability,

however the output torque will also decrease in this case. A081 AVR function AVR function attempts to maintain a stable output voltage by

changing the duty cycle of the PWM output in real-time. If the input

voltage changes or bus voltage changes due to regeneration, motor

sees constant voltage. That means the motor efficiency will be better.

In some cases, disabling the AVR function can resolve motor

instability problems.

AVR function attempts to always mainain constant output voltage.

During operation, DC bus voltage is always changing, which

means AVR function is always acting to change the duty cycle of

PWM output voltage. Since it is an active control function it may

lead sometimes motor instability (unstable energy transmission).

In such cases, setting AVR OFF can solve the problem.

b022 OL restriction level Set OL level [b022] as high as possible, or else disable it

(set [b021] to “00 ”), because a rather high motor current is

required in low frequency area in the case of vector control.

b041~b044 Torque limit level Set torque limit level as high as possible, or else disable it

b083 Carrier frequency

* Second and 3rd functions ([H2**] & [H3**]) have the same meaning for 2nd and 3rd motors.

Refer to Table 3 for standard (default) motor parameter settings for SJ300 series inverter.

High torque cannot be achieved if OL restriction is preformed.

( = assign TL to an intelligent input terminal and leave it OFF),

because high motor current is required in the low frequency area

in the case of vector control.

Maximum torque cannot be achieved if torque limit is triggered.

Decreasing carrier frequency can solve the problem of motor

instability.

This is because the effect of dead time will be reduced.

Table 2 shows suggestions for adjusting the SLV and other related parameters to correct various phenomena.

Table 2. Suggestions for tuning

# Phenomena Parameter How to adjust

Actual speed is faster than the target speed.

(Speed deviation is +) Actual speed is slower than the target speed.

(Speed deviation is - ) Insufficient torque at low speed (~ few Hz) H020

4 Shock at start H024 Decrease J

5 Unstable motor rotation H005 Decrease speed response factor

Insufficient torque at low speed due to torque

limit action

H021

H023

H024 Decrease J

H006

A045 Decrease output gain

A081 Set AVR function to OFF

b083 Decrease carrier frequency

b021,

b041

~b044

H005 Increase speed response factor

Decrease R2 value (Minimum target is 80% of the preset value)

Increase R2 value (Maximum target is 120% of the preset value)

Increase R1 value (Maximum target is 120% of the preset value)

Increase Io value (Maximum target is 120% of the preset value)

Increase / decrease stability control factor (Increase or decrease depends on the situation.)

Set; Torque limit level > Overload restriction level

7 Response is slow

Speed

response

overshoot due to too quick

H050 Increase P-gain of speed response factor

H051 Decrease I-gain of speed response factor

H005 Decrease speed response factor

H050 Decrease P-gain of speed response factor

H051 Increase I-gain of speed response factor

*Refer to Table 3 for a standard (default) motor parameter settings for SJ300 series inverter.

SLV Control block diagram (Fig 1)

Magnetizing

Speed response [H005]

Magnetizing

Stabilization

Motor Constant

Motor Constant Motor Constant

Motor Constant

Motor Constant Motor Constant

ωr*

Speed reference

ωr^

id*

current reference

Speed

control

P gain for PI [H050] I gain for PI [H051] P gain for P [H052] [H070], [H071], [H072]

Motor Constant (R1,L,Io,J)

iq*

(R1, R2, L, Io)

iq* id*

φd*

Voltage calculation

(Interference control)

vq* vd*

Motor

vU* vV* vW*

Voltage conversion

(2φà3φ)

current Io

(R1, R2, L, Io)

iq*

Torque current

id*

Magnetizing

current control

d-axis secondary

id*

flux control

control

(q-ACR)

(d-ACR)

(R1, R2, L, Io)

∆

Vd∆

ω1*

∆vq0

Compensation

voltage

calculation

(R1, R2, L, Io)

∆vd0

factor [H006]

iq*

φd* ω1* θ

ωr^

Frequency

calculation

φd*

Speed

estimator

ω1*

Integrator

Current converter

(3φà2φ

)

IwIu

Iu Iw

(R1, R2, L, Io)

Vector control technical information

LAC

SJ-FB Option Board Block Diagram

Internal

setting

Inverter main body

PCLR

POK

ORT

STAT

APR

Orientation

control

LAD

Speed deviation

excessive signal

DSE ZS

ASR

Zero speed

detection

Torque

limiter

Speed

detection

ACR

Position

detection

PWM M

SJ-FB

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