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KEB COMBIVERT F5-A,-E,-H 4.0. APPLICATION MANUAL (2008) - page 13

Torque Control

7.9.3. Speed calculation

The setpoint speed according to the ramp generator (ru.02) is used for speed limiting.

The setpoint speed is formed (with exception of the direction of rotation) exactly as in the vector controlled and

open loop operation, respectively. The direction of rotation is indicated by the sign of the torque reference.

Without limiting the speed, the drive would accelerate to indefinitely high speeds if the counter torque disap-

pears.

Since the limiting is based on the speed at the ramp generator output, the acceleration-/deceleration ramps

should be set to 0 s for this operating mode.

7.9.4. Control mode

For the torque-controlled operation, 2 different modes exist that can be selected with cS.00 = 5 or cS.00 = 6 .

7.9.4.1Mode 1: torque-controlled operation with emergency switching to speed control

This mode is activated via cS.00 = 5.

The speed controller is not active as long as the drive does not exceed the maximum speed for torque-con-

trolled operation (= setpoint speed ru.02) .

This has the advantage that the parametrisation of the speed controller has no effect on the set torque.

The switch to vector controlled operation happens only on reaching the speed limit. The switching causes sub-

optimal controller behaviour and overshoots can occur.

Figure 7.9.4.1 Mode 1

ru.07

"Actual value display"

(Actual speed)

Speed controller

Set

Set

torque

speed

-

Amount of parameter ru.02

"Ramp output display"

Actual speed

CS.15

>

Sign

Set speed

Torque

Torque

reference

reference

source

Analog ref

0

Speed

controller in

Analog aux

1

+100%

limit

Abs. torque reference (CS.19)

2

"Actual ref.

Torque ref. setting % (CS.18)

3

-100%

Torque acc. time

torque" ru.49

CS.16

Motor poti (ru.37)

4

Ext. PID outdisp. (ru.52)

5

AN2 direct (quick scanning)

6

CS.19

"Absolute torque reference"

Page7.9 - 4

Torque Control

7.9.4.2Mode 2: torque-controlled operation with superimposed speed control

This mode is activated via cS.00 = 6.

The speed controller is permanently active, but the limit of the controller is always set equal to the torque re-

ference.

As long as the drive does not exceed the maximum speed for torque-controlled operation (= setpoint speed ru.

2), the speed controller is within the limits, i.e., its output signal is equal to the torque reference.

This mode has<the advantage that the speed controller is always active, leading to better behaviour when

reaching the maximum speed .

The disadvantage is that with an unfavorable parametrisation of the speed controller (e.g., very small amplifica-

tion chosen), the torque reference can be further delayed by the controller. I.e., even if the ramp time is cS.16

= 0:off, the speed controller must first run to the new limit value after an increase of the torque reference .

Figure 7.9.4.2 Mode 2

ru.07

"Actual value display"

(Actual speed)

Speed controller

Set

Set

Torque

torque

speed

-

reference

Amount of parameter ru.02

"Ramp output display"

CS.15

Sign

Torque

reference

source

Analog ref

0

Analog aux

1

+100%

7

Abs. torque reference (CS.19)

2

"Actual ref.

Torque ref. setting % (CS.18)

3

-100%

Torque acc. time

torque" ru.49

CS.16

Motor poti (ru.37)

4

Ext. PID out disp. (ru.52)

5

AN2 direct (quick scanning)

6

CS.19

"Absolute torque reference"

Page7.9 - 5

Current Control, -Limiting and Switching Frequencies

7.10 Current control, -limiting and switching frequencies

7.10.1Current control

Current controller (dS.00 „KP current“, dS.01 „KI current“) are automatically pre-charged by operation of Fr.10

by means of equivalent circuit data.

The controller parameters are calculated from the equivalent circuit data.

The current decoupling must be activated for an optimal control characteristic.At the asynchronous motor it is

differentiated between "1: on "and "2: on, without main inductance".

Mode 2 (without main inductance) must be used if strong DC link voltage fluctuations occur (e.g. at compliant

supply or spindle motors). The complete decoupling can lead to boosted current oscillation.

Otherwise mode „1: on“ for synchronous and asynchronous motor must be selected.

dS.02: Current decoupling

Value

Explanation

0: off

Current decoupling off

1: on

Current decoupling on

2: on, without main

partial current decoupling (mode only for asynchronous motors at unsteady DC

inductance (ASM)

link voltage)

Exception: The controller parameters are only calculated depending on the motor type plate data at speed

controlled operation of an asynchronous motor without motor model. These adjustments are default values

for standard motors and they are not suitable for special motors (e.g. high and medium frequency motors). A

manual adaption must be made here.

A current decoupling is also not possible since the equivalent circuit data are unknown. Parameter ds.02 must

set to value 0.

7

dS.03: Current / torque mode

Bit

Meaning

Value

Explanation

0: off

Current controller/ priority

4

Activation of the active current controller-priori-

assignment (ASM)

16: on

ty in the regenerative range

Attention: A change of bit 4 in parameter ds.03 is usually not necessary and should be done

only by authorized KEB service personnel.

The active current controller can get priority in generatoric operation with bit 4 of parameter ds.03. In special

applications this is of advantage for the quality of the current control.

Page7.10 - 3

Current Control, -Limiting and Switching Frequencies

7.10.2.

Current limit

The hardware current limit becomes active, if the phase current exceeds the value in In.18 „hardware current

inverter“.

Through short-time power shutdown the current limit can avoid short current peaks at small speed, e.g. when

starting the motor.

However if the current level is exceeded at high speed under load, disconnection of the voltage leads to a

reduction of the breakdown torque of the motor and thus to a "fall back" of the motor. The motor model is also

invalid. Therefore this function should be switched off for controlled drives.

Attention: The hardware current limit limits the current at the limit and releases no error. This can lead to torque

sags at the motor shaft. This function is very critical especially at the operation "hoist and lowering". Because

the drive can sag caused by missing torque, without brake engage.

Sole exception: Current overshoots can occur during the start in speed controlled operation with encoder feed-

back without motor model if the current controllers are not optimal adjusted. They can be absorbed with uF.15

= 1: "single-phase mode".The hardware current limiting makes sense also at controlled drives.

uF.15 Hardw. curr. lim. mode

Value

Explanation

0

Off: recommended adjustment at controlled operation

1

Single-phase mode: limits the current reliably, but deep current engage

2

Zero vector mode: lower current engage, but overcurrent errors can occur in unusual cases.

The software current limiting should be used instead of the hardware protective function. The maximal permis-

sible current must be entered in parameter dr.37.

It is reasonable to enter the hardware current level (In.18) here if the application does not require another value.

The function is activated by setting "curr./torq.mode = 1: on" in parameter (ds.03).

dS.03: Current / torque mode

Bit

Meaning

Value

Explanation

0: off

0

Maximum current mode

1: on

Activation of the software current limiting

Page7.10 - 4

Current Control, -Limiting and Switching Frequencies

7.10.3Switching frequencies and derating

7.10.3.1

Switching frequency (uF.11, In.03, In.04, ru.45)

The desired switching frequency can be selected in parameter uF.11. The higher the switching frequency the

smaller the noise level and the smaller the current ripple and the losses in the motor involved. Simultaneously

the losses in the inverter and also the isolation straining of the motor increase caused by switching edges.

uF.11 Carrier frequency

Value

Frequency

0

2 kHz

1

4 kHz

2

8 kHz

3

12 kHz

4

16 kHz

The current ripple is a harmonic current which superimposes the sine-wave output current.

It is generated by the clocked output voltage of the frequency inverter. This ripple increases the maximum value

of the current and this can release an overcurrent error or hardware current limit, although the displayed appa-

rent current (ru.15) and/or the actual utilization value (ru.13) is clearly below this limits.

Picture 7.10.3.1 Switching frequencies

20

15

10

Base frequency of the phase

5

7

current

0

-5

actual current = base frequency

-10

with superimposed ripple

-15

-20

0.0955

0.096

0.0965

0.097

0.0975

0.098

0.0985

0.099

0.0995

The size of the current ripple is depending on the switching frequency and the motor inductance. The current

ripple is usually insignificant for standard motors with a power < 50kW and a rated switching frequency of the

unit of min. 4 kHz.

The smaller the leakage inductance (ASM) and/or the winding inductance (SM) the higher the ripple. This is

especially the case at motors with high power or spindle motors. Therefore the switching frequency must be

selected as high as possible for these motors.

Attention: Generally the switching frequency should be at least 10 times higher than the maximally occuring

output frequency of the inverter.

The maximum switching frequency can be read off in parameter In.03. The frequency inverter can be operated

permanently only with its rated carrier frequency (In.04) (independent on temperature and utilization).

If a switching frequency is selected in parameter uF.11 which is higher than the rated value, an automatic

"derating" i.e. a reduction of the switching frequency occurs depending on temperature, output frequency and

utilization of the inverter. This carrier frequency change-over is generally not good for the control response of

the drive. Therefore the carrier frequency uF.11 should be equal to the rated carrier frequency. However the

effects of the deratings can be neglected in many applications.

Page7.10 - 5

Speed Measurement

7.11 Speed measurement

7.11.1 Designs

The KEB COMBIVERT F5 supports two from each other separated encoder channels. Each encoder channel

can support following interface dependent on the available hardware:

Encoder channel 1 (X3A)

•

is a 15 pole incremental encoder input for rectangular signals

Encoder channel 2 (X3B) can support following interfaces

•

9 pole incremental encoder input for rectangular signals

•

Incremental encoder output

•

Incremental encoder in-/output

Further interfaces (describes in separate manuals)

•

Synchronous serial interface (SSI)

•

Tachometer input

•

Initiator input

•

Hiperface

•

Endat

•

SinCos

7.11.1 Encoder interfaces

7

X3B X3A

X3B X3A

Page7.11 - 3

Speed Measurement

7.11.2 Encoder interface channel 1 (X3A)

7.11.2.1

TTL incremental encoder input (standard at F5-M)

Fig. 7.11.2

Encoder Interface Channel 1 (X3A)

Only when the inverter is switched off and the

5

4

3

2

1

voltage supply is disconnected may the plug

10

9

8

7

6

be pulled out or plugged in !

15

14

13

12

11

Signal

X3A

Description

U_var

11

Supply voltage for encoder

+5 V

12

Supply voltage for encoder

0 V

13

Reference potential

A

8

Signal input A

_

A

3

Signal input A inverted

B

9

Signal input B

4

Signal input B inverted

n

15

Reference marking input N

14

Reference marking input N inverted

Shield

housing

shielding

Following specifications apply to the encoder interface 1 (X3A):

-

Limiting frequency of input fG = 300 kHz

-

internal terminating resistor Rt = 150 ohm

-

2…5 V High level at rectangular signals

Inputs

The signal and reference marking inputs can be triggered with rectangular pulses. The signal inputs must ge-

nerally be connected. The reference marking signals are only needed for the reference point approach in the

positioning operation (F5M/S).

Please contact KEB regarding encoder inputs with HTL level!

Page7.11 - 4

Speed Measurement

Fig.7.11.2.a Resolver interface channel 1 (X3A)

Only when the inverter is switched off and the vol-

5

4

3

2

1

tage supply is disconnected the plugs may be pulled

10

9

8

7

6

out or plugged in !

15

14

13

12

11

Signal

X3A

KEB servo motor

Description

SIN -

3

1

Sinus signal cable inverted

SIN+

8

10

Sinus signal cable

REF-

5

5

Reference signal inverted

REF+

10

7

Reference signal

COS-

4

2

Cosine signal cable inverted

COS+

9

11

Cosine signal cable

GND

14

-

Shielding of the signal cables

Shield

housing

housing

shielding of the hole cable

Fig. 7.11.2.b Resolver connector at the KEB servo motor

7

6

8

12

5

9

11

10

1

4

2

3

7

Fig. 7.11.2.c Resolver cable

housing

housing

Core color

14

GND

SIN-

1

3

SIN -

red

SIN+

10

8

SIN+

blue

REF-

5

5

REF-

yellow

REF+

7

10

REF+

green

COS-

2

4

COS-

pink

COS+

11

9

COS+

gray

Page7.11 - 5

Speed Measurement

7.11.3 Encoder interface channel 2 (X3B)

Fig. 7.11.3

Encoder interface channel 2 (X3B)

Only when the inverter is switched

5

4

3

2

1

off and the voltage supply is dis-

connected may the plug be pulled

9

8

7

6

out or plugged in !

Channel 2 can be equipped with different interfaces. To avoid the connection of a wrong encoder, the installed

interface is indicated in Ec.10.

Definition of the interface (Ec.10)

Channel 2 can be equipped with different interfaces. To avoid the connection of a wrong encoder, the installed

interface is indicated in Ec.10.

7.11.3.1

Incremental encoder input

In synchronous operation the second incremental encoder serves as input of the master drive. A second posi-

tion encoder can be connected for positioning operation.

Signal

X3B

Description

U_var

5

Supply voltage for encoder (see 7.11.2)

+5,2V

4

Supply voltage for encoder (see 7.11.2)

0 V

9

Reference potential

A

1

Signal input A

_

A

6

Signal input A inverted

B

2

Signal input B

_

B

7

Signal input B inverted

n

3

Reference marking input N

_

N

8

Reference marking input N inverted

Shield

housing

shielding

The signal inputs of the second encoder interface support only rectangular signals.

Following specifications apply to the encoder interface 2 (X3B):

-

Limiting frequency of input f_G = 300 kHz

-

internal terminating resistor Rt = 150 Ω

-

2…5 V High level at rectangular signals

Page7.11 - 6

Speed Measurement

7.11.3.2

Incremental encoder output

The incremental encoder output gives out the signals recorded at the encoder interface 1:1 in RS422 specifi-

cation over the second channel (e.g. master drive in synchronous operation).

Signal

X4A

Description

U_var

5

Supply voltage for encoder (see 7.11.2)

+5,2V

4

Supply voltage for encoder (see 7.11.2)

0 V

9

Reference potential

A

1

Signal input A

_

A

6

Signal input A inverted

B

2

Signal input B

_

B

7

Signal input B inverted

n

3

Reference marking input N

_

N

8

Reference marking input N inverted

Shield

housing

shielding

Encoder 2 operating mode (Ec.20)

The function of the encoder interfaces is defined with parameter Ec.20.

Ec.20: Encoder 2 operating mode

Bit

Description

Value

Function

0

Incremental encoder input

7

1

Channel 2 Function

1

Incremental encoder output

0

Input with terminating resistor

2

Terminating resistor at channel 2

2

Input without terminating resistor

Channel 1 incremental encoder

0

without alarm

3

alarm

(encoder breakage refe-

4

with alarm (encoder must support alarm)

rence)

channel 2 incremental encoder

0

without alarm

4

alarm

8

with alarm (encoder must support alarm)

channel

1 without incremental

0

without alarm

5

encoder

16

with alarm

channel

2 without incremental

0

without alarm

6

encoder

32

with alarm

Page7.11 - 7

Speed Measurement

7.11.4 Voltage supply of encoder

Fig. 7.11.4 Voltage supply

X3A

Uvar

5,2V

+5,2V

X2A

0V

0V

22

X3B

+20...30VDC

21

Uvar

+5,2V

0V

+24VDC 0V

Uvar , +5 V

Uvar is a unstabilized voltage, which is made available from the power circuit of the KEB COMBIVERT. Depen-

ding on the unit size and the load it can be 15...30 V DC. Uvar can be loaded at X3A and X3B altogether with

max.170 mA. If higher currents are required for the supply of the incremental encoder, the FI must be supplied

with an external voltage.

The +5,2 V voltage is a stabilised voltage, which at X3A and X3B is loadable with altogether 500 mA. Since the

+5,2 V are generated from Uvar, the current from Uvar decreases in accordance with following formula:

5,2 V x I_+5V

I_var = 170 mA -

-————

Uvar

7.11.5 Selection of encoder

Precondition for a good control characteristics of a drive is not at least a question of the selection and the cor-

rect connection of the encoder. This also includes the mechanical as well as the electrical connection.

Max. operating frequency (max.sampling frequency)

Depending on the max. operating frequency of the encoder input, the encoder and the maximum speed of the

drive the line number of the encoder can be selected.

Page7.11 - 8

Speed Measurement

7.11.5 Speed and line number in dependence on the max. operating frequency of the

encoder inputs

10000

200 kHz

300 kHz

1000

1000

Line number z

10000

The max. signal frequency, which is given out by the encoder, is calculated as follows:

n_max[rpm] x z

f_max [kHz] =

-——————

60000

f_max:

max. signal frequency

7

n_max: max. speed

z:

encoder line number

The following condition must be met:

f_max < max. operating frequency of encoder < max. operating frequency of interface

7.11.5.1

Cable length

To achieve an unobjectionable function following cable lengths should not be exceeded. Precondition is that the

supply voltage at the rotary encoder is within the specified tolerances.

The encoder lines should not be longer than 50 m. If longer cables are needed, please contact KEB.

Further information can be taken from the documentation of the respective manufacturer.

Page7.11 - 9

Speed Measurement

7.11.5.2

Signal sequence / level

7.11.5.a Signal tracks A+, B+

!

6

#/-

6

!

6

#/-

6

"

6

#/-

6

"

6

#/-

6

T

Evaluation of the zero signal

The zero signal is required for referencing and/or correction of the position value. The signal must not be con-

nected at normal speed controls (see alarm evaluation Ec.41). The maximum permissible length of the zero

signal of the encoder is visible in the following signal sequence. The zero signal is acquired when A+ ,B+ and

N+ are on high level. Thus there is only one valid position value independent of the travel direction.

7.11.5.b Evaluation of the zero signal

!

6

#/-

6

!

6

#/-

6

"

6

#/-

6

"

6

#/-

6

T

Page7.11 - 10

Speed Measurement

7.11.6 Encoder identifier

Prior to start-up the inverter must be adapted to the encoder(s) which is/are used.

Encoder interface 1 / 2 (Ec.00, Ec.10)

Ec.00 displays the installed encoder interface 1; Ec.10 displays the encoder interface 2. The values correspond

to following interfaces:

Ec.00, Ec.10: Encoder interface 1/ 2

Value

Description

0

no

1

TTL-Incremental encoder input

2

Incremental encoder output 5 V TTL

3

Incremental encoder input and output direct

(non-divisible with Ec.27; switchable with Ec.20)

4

Incremental encoder input and output TTL (switchable with Ec.20)

5

Initiator

6

Synchronous serial interface (SSI)

7

Resolver

8

Tachometer

9

Incremental encoder output TTL (from resolver over channel 2)

10

Incremental encoder output TTL

11

Hiperface

7

12

Incremental encoder input 24 V HTL

13

Incremental encoder input TTL with error detection

14

SinCos encoder input

15

Incremental encoder input 24 V HTL with error detection (push-pull)

16

ENDAT

17

Incremental encoder input 24 V HTL with error detection

18

Analog option ±10 V

19

Resolver

20

SSI sincos

21

Overspeed limiter

22

UVW-Interface

23

Inc. simulation 10-30V

24

Inc. simulation 10-30V

25

Overspeed limiter HTL

26

Inc. input TTL with error detection 5V supply terminal

In case of an invalid encoder identification, error "E.Hyb" is indicated and the measured value is displayed

inverted in Ec.00 / Ec.10.

On changing the encoder interface the error "E.HybC" is indicated. By writing on parameter Ec.00 or Ec.10 the

change is confirmed and the default values for the new interface are loaded.

Page7.11 - 11

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