Technical Description TRA Page Error! Bookmark not defined.
TECHNICAL DESCRIPTION
PULSE WIDTH MODULATED
4-QUADRANT SERVO-CONTROLLER
TYPE
TRA
IMPORTANT!
* It is of vital importance that you read the technical description before starting-up
* Protect the unit from aggressive and electrically conductive media. They could cause malfunction and/or destroy the unit!
* Do not touch any life parts. Danger to life!
* Installation, connection and starting-up may only be carried out by an expert subject to all relevant safety regulations.
* Assured properties and functions of the unit are only guaranteed when expertly handled.
* Tamperings and modifications that have not been expressly authorized by us, as well as any non-authorized use result in the exclusion of any guarantee and liability.
* Basis for any legal business with us are our "Allgemeine Gesch‰ftsbedingungen " (General Terms of Business).
* All documentations, drawings, diagrams etc. are subject to copyright terms. Any use, duplication, forwarding, processing and alteration without our explicit consent is prohibited.
Table of Contents
Page
1. Technical Description 4
1.1 General introduction 4
1.2 Model overview 4
1.3 Technical data 5
1.4 Control principle 6
1.5 Description of function 7
1.6 Block diagram 9
1.7 Overview setting possibilities / displays 10
1.8 Front view 11
2. Connecting the Unit 12
2.1 Plug wiring 12
2.2 Explanation of plug wiring 13
2.3 Proper polarity of motor and tachometer 14
2.4 Input monitoring circuit 15
2.5 Connection diagram (proposal) 16
2.6 Running of wires 17
3. Starting-up 17
3.1 Presettings 17
3.2 Setting of pulse and effective current 18
3.3 Tachometer adaptation 18
3.4 EMK and IxR compensation 18
3.5 Offset-rectification 19
4. Optimizing the control behaviour 19
4.1 Amplification of alternating voltage 19
4.2 Amplification of direct voltage 19
4.3 Tachometer screening 19
4.4 Integral part of speed controller 20
Appendix: Line-up diagrams
Basic printed circuit board TRA
Speed control module TRA-D
1. Technical Description
1.1 General Introduction
4-Quadrant Servo-Controller for 2 motor axes
The units of the TRA-construction series consist of 2 independent servo-controllers for permanently energized DC motors which are operated on the same intermediate circuit.
Both controllers as well as the mutual grid system part and a combinational circuit part for the supply of the electronic for both axes are on a double Europe card. This way very economic solutions in view of expense, space and energy requirements are possible. The application possibilities comprise mainly those in need of two or more axles, that means e.g. X-Y-drives or coiling automatons. The unit can be supplied only as a current controller, or by adding a plug module also as a speed controller with tacho return circuit and/or EMK / IxR-control. The use of SMD-technique and power-MOSFETs guarantees good efficiency and a compact construction. The installation width is only 8 TE.
The units dispose of a short-circuit and earth fault protection as well as of all standard control, protection and supervision possibilities. Nominal voltages of 60 V and 120 V each and nominal currents of 6A and 12A can be realized. For acceleration and braking purposes, the 2.5-fold pulse current is for about 3 seconds at disposal.
1.2 Model overview
Designation / nominal output / nominal / pulse / minimum load / fusesof unit / voltage / current / current / inductivity
TRAS60/6DD / 60V / 6A / 15A / 0,8 mH / 16A
TRA60/12DD / 60V / 12A / 30A / 0,4 mH / 25A
TRA120/5DD / 120V / 5A / 10A / 1,6 mH / 16A
TRA120/10DD / 120V / 10A / 20A / 0,8 mH / 25A
TRAB48/12DD / 48V / 12A / 30A / 0,4 mH / 25A
All units can also be obtained as current controllers only. Then the designation changes from TRA...DD to TRA...DS. The first "D" stands for double controller, the second for speed controller and/or with "S" for current controller.
Recommended transformer voltages for nominal operation:
(effective values under consideration of + 5% no-load/full load and +10 % mains overvoltage)
TRA60/6D.. / 52 V, 3~AC/ 9 ATA60/12D.. / 52 V, 3~AC/ 18 A
TRA120/5D.. / 95 V, 3~AC/ 7,5 A
TRA120/10D.. / 95 V, 3~AC/ 15 A
1.3 Technical Data
* maximum intermediate circuit voltage / (85) / 170 / VDC
* stroke frequency of output stage / 9 / KHz
* frequency of current ripples / 18 / KHz
* frequency-range of subordinated current controller / 1 / KHz
* maximum input drift / ± 21 / µV/∞C
* minimum load inductivity / see model survey
* over-all efficiency appr. / 93 / %
* output current shaping factor / Error! Bookmark not defined. 1,001
(with min. load inductivity with nominal current and voltage)
* voltage range of differential input / ± 10 / V
* internal resistance of rated value input / 20 / KOhm
* input attenuation via resistor RE / 0-100 / %
* voltage range of tachometer inputs
(with Usoll = ±10 V and nominal speed)
with RE = 20 KOhm / 14,5 - 86 / V
with RE = 10 KOhm / 7,25 - 43 / V
with RE = 3,3 KOhm / 3,4 - 20,2 / V
* auxiliary voltage for add. external circuits / ±15 V / / 50 / mA
* ready-for-operation pilot relay / max.100V / /100 / mA
* I2T message (open-collector-output) / ± 15 V / / 50 / mA
* anchor current monitor (output) / 1 V / = 10 / %
(of the unit specific pulse current)
* enable (input) active at / 12 V / - 35 / V
Available Options
* Front plate
* ballast circuit
* bus PCBs
* current control
1.4 Control Principle
Servo-controllers TRA operate on the principle of speed control with a subordinated current control circuit. The signal flow chart of this control principle is illustrated in the following diagram:
nominal speed nominal regulated
value current value quantity
speed current current PWM motor
controller limitations controller output tacho
stage
actual current value
actual speed value
The current control circuit consists of a current controller and of the amplifier output stage. The respective actual current value is determined at the output of the output stage and fed back to the point of summation. The speed controller supplies the nominal current value. (*) Nominal and actual values are compared and the difference is fed to the current controller.
The superordinated speed control circuit consists of a speed controller, a current control circuit and a motor/tachometer combination. The nominal speed value is externally preset by the user, like e.g. by potentiometer, NC-control. The actual speed value is determined directly on the motor shaft, e.g. by a tacho alternator, and is compared on the first point of summation with the nominal speed value. The difference getting known this way is the input regulated quantity of the speed controller. It shapes from the control difference the required nominal current value.
The advantage of this control principle is that a very stable control behaviour is achieved as the subordinated current controller can react quickly to disturbance variables and relieves such the speed controller. In addition, current limitations required for the protection of motor and amplifier, can be realized in a simple way only by limiting the output voltage of the speed controller (nominal current value).
(*) In some applications a superordinated position control circuit already takes care of the speed control. Therefore the TRA can be modified in such a way that it works only as current controller - please consult our technicians in case of demand.
1.5 Description of Functions with Block Diagram
a. Voltage supply
The functions of the amplifier are explained by way of a block circuit diagram (see page 9). The first block concerns rectification and screening. In this part of the circuit, the required direct voltage UCC (intermediate circuit voltage) which is required for operating the unit, is generated from the alternating voltage supply.
With this voltage the output stage is supplied and it is used at the same time for generating the auxiliary voltage Error! Bookmark not defined. 15 V by means of the circuit power supply required for the supply of the control part.
b. Control part
The nominal speed value is fed to the differential input and can be preset by means of RE (see page 22) in different areas. For obtaining the actual speed value there are two possibilities:
1. with the aid of a tacho-alternator
The output voltage of the tacho-alternator is conducted to a RC-member (smoothing of tachometer voltage). With the fixed resistor RE tacho-alternators of different EMK are adapted to the control.
2. with the "EMK"- and IxR-compensation
In this case a part of the armature voltage of the motor which is measured with the UA-measuring circuit, is used as actual speed value. In addition, with the IxR-compensation the current proportional voltage drop on the internal resistance of the motor can be balanced.
By means of the two soldering bridges tacho/IxR (right and left below the plug module TRA-D) must be chosen how the actual speed value is entered. In the factory the corresponding soldering bridges are set to tacho operation (see page 22).
At summation point SP1 nominal and actual speed values are compared. The control difference is amplified from the PI-speed controller with the related counter-coupling power supply and the control deviation is balanced to O. The starting regulated quantity of the speed controller is the nominal current value (SP 2). Here engage also all current limitations:
- effective current limitation
The actual armature current value is fed to this circuit, quadrated there and filtered with a subsequent low-pass, with the time constant T = 8,2 s. The actual effective current value obtained this way is compared with an adjustable nominal value. If the two values are approaching, the circuit reduces the nominal current value required from the control so far that there is no further rise of the actual effective current value.
- internal limitation of nominal current value with P1a (P1b)
This current limitation is subsequently added to all limitations. That means that the pulse current set on P1 can on no account be exceeded.
The limited nominal current value is fed to summation point SP3. The actual current value still missing for a nominal/actual-comparison is measured by the armature current measuring circuit and fed to summation point SP3 as well.
The current controller generates from the comparison of nominal and actual current value the regulated quantity for the 4-quadrant output stage. The current controller is a PI-controller with a proportional amplification Kp = 3,12 and a resetting time of TN = 1ms. As this is an impulse generated controller, the continuous regulated quantity must be transformed to a pulse width modulated signal. This occurs in the pulse width modulator in which the regulated quantity is modulated with a triangle voltage of the frequency 9 KHz, and out of which the signals for the driver stage are shaped.
By a special modulation principle one obtains a doubling of the current flow frequency (18 KHz) which ensures a low noise operation.
Because transistors switch on faster than they switch off, it is necessary to delay the switch-on-signals a little in order to prevent that two quadrants of the output stage are conducting at the same time. This signal delay is realized in the dead time formation.
c. Driver and Output Stage
The driver stage amplifies the signals coming from the pulse width modulator. It is designed for an optimum approach of the output stage. This ensures for any kind of operation a loss-free and safe operation of the output stage, its MOSFET-switch transforming the signals which are placed at disposal from the driver stage, into power.
1.6 Blockdiagram TRA
generation of rectification
auxiliary volt. and screening
nominal value diff. speed nominal current pulse width
amplifier controller current controller modulator and
value limitation dead time
formation
tacho IxR
soldering bridge
tacho input UA-meas.circuit I2T/ I eff. IA-measuring
a.filter IxR-compensation current limit. circuit
protective and moni-
toring circuits
1.7 Survey of Displays and Setting Possibilities
LED 1 (green) : Indicates operating condition of unit. Shines also when amplifier is switched to "Disable".
LED 2 (red): Shines in case of trouble (overvoltage, excess current and/or excess temperature); after this LED has started shining the amplifier can only be reactivated by switching it off and then on again.
LED 3 (yellow): Effective current limitation (I2 t), amplifier A, shines after expiration of the pulse current phase.
LED 4 (yellow): Same function as LED 3, but for amplifier B.
Amplifier A:
Potentiometer 1A: Pulse current limitation setting range 10-100% of the unit specific pulse current
Potentiometer 2A: effective current limit value, setting range 0 - 100% of the unit specific effective current
Potentiometer 5A: voltage divider for tachometer input
Potentiometer 6A: offset balance of speed controller
Potentiometer 7A: alternating voltage amplifier of speed controller
Potentiometer 8A: EMK-potentiometer, control by means of fed back motor voltage (setting range 1: 4,3)
Amplifier B:
The potentiometers of amplifier "B" have the same functions as amplifier "A". In addition they bear the letter "B".
Please note:
The potentiometers P5A-P8A and P5B-P8B are on the plug module "TRA-D" (speed control). When the unit is used as a current controller these potentiometers do not exist.
1.8 Front View
Ready for operation
LD3: trouble
LD3: I2 + (A) EMK
LD4: I2 + (B) tacho
offset
amplifier
I-pulse A n-actual
n-nominal I-actual
I-effective A U-actual
I-pulse B n-actual
n-nominal
I-actual
I-effective B U-actual
ÌV EMK
tacho
offset
amplifier
B
heat sink
TRA
2. Connecting the Unit
2.1 Plug Wiring
ST2 Signal Plug DIN 41612-D32 ST1 Power Plug H15 DIN 41612
------
2a / input A (+) / 4 / motor B (+)2c / input A (-) / 6 / motor B (-)
4 a,c / 0 V / 8 / motor A (+)
6 a / IA - monitor A / 10 / motor A (-)
6 c / UA - monitor A
8 a / 0 V / 12
8 c / I2t-message A / 14 / 0 Volt mass
10 a / tacho A (+) / 16
10 c / tacho A (-)
12 a / 0 V / 18
12 c / + 15 V / 20 / AC-supply
14 a / 0 V
14 c / - 15 V / 22 / AC-supply (with three-phase
16 a / tacho B (+) / 24 / current only)
16 c / tacho B (-)
18 a / + 15 V / 26
18 c / enable A / 28 / AC-supply
20 a / + 15 V
20 c / enable B / 30
22 a / input B (+) / 32 / + UCC
22 c / input B (-)
24 a,c / 0 V
26 a / IA-monitor B
26 c / UA-monitor B
28 a / 0 V
28 c / I2t-message B
30 a,c / NC (not occupied)
32 a / ready for operation (potential-free reed contact)
32c / ready for operation (for both axles together)
2.2. Explanation of Plug Wiring