Power section and cooling

SIMOREG 6RA70 converters are fully digital, compact units for connection to a three-phase AC supply. They in turn supply the armature and field of variable-speed DC drives. The range of rated DC currents extends from 15 A to 3000 A, but can be expanded by connecting SIMOREG converters in parallel.

Converters for single-quadrant or four quadrant operation are available to suit individual applications. As the converters feature an integrated parameterization panel, they are autonomous and do not require any additional parameterization equipment. All open-loop and closed-loop control tasks as well as monitoring and auxiliary functions are performed by a microprocessor system. Setpoints and actual values can be applied in either analog or digital form.

SIMOREG 6RA70 converters are characterized by their compact, space-saving design. An electronics box containing the closed-loop control board is mounted in the converter door. This box also has space to hold additional boards for process-related expansion functions and serial interfaces. This design makes them especially easy to service since individual components are easily accessible.

External signals (binary inputs/output), analog inputs/outputs, pulse encoders, etc.) are connected by way of plug-in terminals. The converter software is stored in a flash EPROM. Software upgrades can easily be loaded via the serial interface of the basic unit.

Power section: Armature and field circuit

The armature circuit is a three-phase bridge connection:

As a fully controlled B6C three-phase connection in converters for single-quadrant drives

As two fully controlled (B6) A (B6) C three-phase connections in converters for four-quadrant drives.

The field circuit is a half-controlled B2HZ single-phase bridge connection.

For converters with 15 to 1200 A

rated DC current, the power section for armature and field is constructed with isolated thyristor modules. The heat sink is therefore at floating potential.

For converters with rated currents ≥ 1500 A, the power section for armature and field is constructed with disc-type thyristors and heat sinks at voltage potential. All connecting terminals for the power section are accessible from the front.


Converters with rated DC currents up to 125 A are self-cooled, while converters with rated DC currents of 210 A and higher have forced-air cooling (fan assembly).

Parameterization devices

PMU simple operator panel

All units feature a PMU panel mounted in the converter door. The PMU consists of a five-digit, seven-segment display, three LEDs as status indicators and three parameterization keys.

The PMU is also equipped with connector X300 with a USS interface in compliance with the RS232 or RS485 standard.

The panel provides all the facilities required during start-up for making adjustments or settings and displaying measured values. The following functions are assigned to the three panel keys:

  • P (select) key
  • Switches over between parameter number and parameter value and vice versa, ack-nowledges fault messages.
  • UP key
  • Selects a higher parameter number in parameter mode or raises the set and displayed parameter value in value mode. Also selects a higher index on indexed parameters.
  • DOWN key
  • Selects a lower parameter number in parameter mode or reduces the set and displayed parameter value in value mode. Also selects a lower index on indexed parameters.
  • LED functions
    • Ready: Ready to operate, lights up in the “Wait for operation enable” state.
    • Run: In operation, lights up when operation is enabled.
    • Fault: Disturbance, lights up in “Active fault” status, flashes when alarm is active.

The quantities output on the five-digit, seven-segment display are easy to understand, e.g..

    • Percentage of rated value
    • Servo gain factor
    • Seconds
    • Amperes or
    • Volts

OP1S converter operator panel

The OP1S optional converter operator panel can be mounted either in the converter door or externally, e.g. in the cubicle door. For this purpose, it can be connected up by means of a

5 m long cable. Cables of up to 200 m in length can be used if a separate 5 V supply is available. The OP1S is connected to the SIMOREG via connector X300.

The OP1S can be installed as an economic alternative to control cubicle measuring instruments which display physical measured quantities.

The OP1S features an LCD with 4 x 16 characters for displaying parameter names in plain text. English, German, French, Spanish and Italian can be selected as the display languages. The OP1S can store parameter sets for easy downloading to other devices.

  • Keys on OP1S:
  • Select key (P)
  • UP key 1)
  • DOWN key
  • Reversing key 1)
  • ON key 1)
  • OFF key 1)
  • Inching key (Jog) 1)
  • Numeric keys (0 to 9)
  • LEDs on OP1S:
  • Green: Lights up in “Run”, flashes in “Ready”
  • Red: Lights up with “Fault”, flashes with “Alarm”
  • RESET key 1)

Parameterization devices

Parameterization via PC

To allow start-up and troubleshooting using a PC, the DriveMonitor software is supplied with the converters.

The PC is linked to the SIMOREG via the USS interface on the basic unit.

The software provides the following functions:

  • Menu-assisted access to parameters.
  • Reading and writing of parameter sets.
  • Copying of existing parameter sets to other converters of the same type.
  • Output of parameter sets to a printer.
  • Operation via control words (binary commands such as ON/OFF instructions, etc.) and specification of setpoints.
  • Monitoring via status words (checkback information about converter status) and readout of actual values.
  • Reading of fault messages and alarms.
  • Readout of trace buffer contents (oscilloscope function)

1) This function must be activated with parameters and is freely selectable.


Software structure

Two powerful microprocessors (C163 and C167) perform all closed-loop and drive control functions for the armature and field circuits. Closed-loop control functions are implemented in the software as program modules that are “wired up” via parameters.


All important quantities in the closed-loop control system can be accessed via connectors. They correspond to measuring points and can be accessed as digital values. 14 bits (16,384 steps) correspond to 100 % in the standard normalization. These values can be used for other purposes in the converters, e.g. to control a setpoint or change a limit. They can also be output via the operator panel, analog outputs and serial interfaces.

The following quantities are available via connectors:

Analog inputs and outputs

Inputs of actual-value sensing circuit

Inputs and outputs of ramp-function generator, limitations, gating unit, controllers, freely available software modules

Digital fixed setpoints

General quantities such as operating status, motor temperature, thyristor temperature, alarm memory, fault memory, operating hours meter, processor capacity utilization


Binectors are digital control signals which can assume a value of “0” or “1”. They are employed, for example, to inject a setpoint or execute a control function. Binectors can also be output via the operator panel, binary outputs or via serial interfaces.

The following states can be accessed via binectors:

Status of binary inputs

Fixed control bits

Status of controllers, limitations, faults, ramp-function generator, control words, status words.

Intervention points

The inputs of software modules are defined at intervention points using the associated parameters. At the intervention point for connector signals, the connector number of the desired signal is entered in the relevant parameter so as to define which signal must act as the input quantity. It is therefore possible to use both analog inputs and signals from interfaces as well as internal variables to specify setpoints, additional setpoints, limitations, etc.

The number of the binector to act as the input quantity is entered at the intervention point for binector signals. A control function can therefore be executed or a control bit output by means of either binary inputs, control bits of the serial interfaces or control bits generated in the closed-loop control.

Switchover of parameter sets

Four copies of parameters with numbers ranging from P100 to P599 as well as some others are stored in the memory. Binectors can be used to select the active parameter set. This function allows, for example, up to four different motors to be operated alternately or four different gear changes to be implemented on one converter. The setting values for the following functions can be switched over:

  • Definition of motor and pulse encoder
  • Optimization of closed-loop control
  • Current and torque
  • limitation
  • Conditioning of speed controller actual value
  • Speed controller
  • Closed-loop field current control
  • Closed-loop e.m.f. control
  • Ramp-function generator
  • Speed limitation
  • Monitors and limit values
  • Digital setpoints
  • Technology controller
  • Motorized potentiometer
  • Friction compensation
  • Flywheel effect compensation
  • Speed controller adaptation.

Switchover of BICO data sets

The BICO data set can be switched over by the control word (binector input). It is possible to select which connector or binector quantity must be applied at the intervention point. The control structure or control quantities can therefore be flexibly adapted.

Motorized potentiometer

The motorized potentiometer features control functions “Raise”, “Lower”, “Clockwise/Counterclockwise” and “Manual/Auto” and has its own ramp-function generator with mutually independent ramp time settings and a selectable rounding factor. The setting range (minimum and maximum output quantities) can be set by means of parameters. Control functions are specified via binectors.

In Automatic mode (“Auto” setting), the motorized potentiometer input is determined by a freely selectable quantity (connector number). It is possible to select whether the ramping times are effective or whether the output is switched directly through to the output.

In the “Manual” setting, the setpoint is adjusted with the “Raise setpoint” and “Lower setpoint” functions. It is also possible to define whether the output must be set to zero or the last value stored in the event of a power failure. The output quantity is freely available at a connector, e.g. for use at a main setpoint, additional setpoint or limitation.

Mode of operation

Optimization run

6RA70 converters are supplied with parameters set to the factory settings. Automatic optimization runs can be selected by means of special key numbers to support setting of the controllers.

The following controller functions can be set in an automatic optimization run:

  • Current controller optimization run for setting current controllers and feedforward controls (armature and field circuit).
  • Speed controller optimization run for setting characteristic data for the speed controller.
  • Automatic recording of friction and moment of inertia compensation for feedforward control of speed controller.
  • Automatic recording of the field characteristic for an e.m.f.-dependent closed-loop field-weakening control and automatic optimization of the e.m.f. controller in field-weakening operation.

Furthermore, all parameters set automatically during optimization runs can be altered afterwards on the operator panel.

Monitoring and diagnosis

Display of operational data

The operating status of the converter is displayed via parameter r000. Approximately 50 parameters are provided for displaying measured values. An additional 300 signals from the closed-loop control can be selected in the software (connectors) for output on the display unit. Examples of displayable measured values: Setpoints, actual values, status of binary inputs/outputs, line voltage, line frequency, firing angle, inputs/outputs of analog terminals, input/output of controllers, display of limitations.

Trace function

The trace function can be selected to store up to 8 measured quantities with 128 measuring points each. A measured quantity or the activation of a fault message can be parameterized as a trigger condition. It is possible to record the pre-event and post-event history by programming a trigger delay.

The sampling time for the measured value memory can be parameterized to between 3 and 300 ms.

Measured values can be output via the operator panels or serial interfaces.

Fault messages

A number is allocated to each fault message. The time at which the event occurred is also stored with the fault message. This allows the cause of the fault to be pinpointed promptly. The most recent eight fault messages are stored with fault number, fault value and hours count for diagnostic purposes.

When a fault occurs

  • The binary output function “Fault” is set to LOW (selectable function),
  • The drive is switched off (controller disable and current I = 0, pulse disable, relay “Line contactor CLOSED” drops out) and
  • An “F” with a fault number appears on the display, the “Fault” LED lights up.
  • Fault messages can be acknowledged on the operator panel, via a binary assignable-function terminal or a serial interface. When a fault has been acknowledged, the system switches to the “Starting lockout” status. “Starting lockout” is cancelled by OFF (L signal at terminal 37).

Automatic restart: The system can be restarted automatically within a parameterizable time period of 0 to 2s. If this time is set to zero, a fault message is activated immediately (on power failure) without a restart. Automatic restart can be parameterized in connection with the following fault messages: Phase failure (field or armature), undervoltage, overvoltage, failure of electronics power supply, undervoltage on parallel SIMOREG unit.

  • Fault/error messages are divided into the following categories:
  • Line fault: Phase failure, fault in field circuit, undervoltage, overvoltage, line frequency
  • < 45 or > 65 Hz
  • Interface fault: Basic unit interfaces to supplementary boards are malfunctioning
  • Drive fault: Monitor for speed controller, current controller, e.m.f. controller, field current controller has responded, drive blocked, no armature current
  • Electronic motor overload protection (I2t monitor for motor) has responded)
  • Tacho-generator monitor and overspeed signal
  • Start-up error
  • Fault on electronics board
  • Fault message from thyristor check: This fault message will only occur if the thyristor check is activated via the appropriate parameter. The check function ascertains whether the thyristors are capable of blocking and firing
  • Fault messages from motor sensors (with terminal expansion option): Monitoring of brush length, bearing condition, air flow, motor temperature has responded
  • External faults via binary assignable-function terminals.

Fault messages can be deactivated individually. The default setting for some fault messages is “deactivated” so they need to be activated in the appropriate parameter.


Special states that do not lead to drive shutdown are indicated by alarms. Alarms do not need to be acknowledged, but are automatically reset when the cause of the problem has been eliminated.

When one or several alarms occur

  • The binary output function “Alarm” is set to LOW (selectable function) and
  • The alarm is indicated by a flashing “Fault” LED.
  • Alarms are divided into the following categories:
  • Motor overtemperature: The
  • calculated I2t value of the
  • motor has reached 100 %
  • Alarms from motor sensors (with terminal expansion option only): Monitoring of bearing condition, motor fan, motor temperature has responded
  • Drive alarms: Drive blocked, no armature current
  • External alarms via binary assignable-function terminals
  • Alarms from supplementary boards.
Safety shutdown (E-STOP)

The task of the E-STOP function is to open the relay contacts (terminals 109/110) for energizing the main contactor within about 15 ms, independently of semiconductor components and the functional status of the microprocessor board (basic electronics). If the basic electronics are operating correctly, the closed-loop control outputs an I = 0 command to de-energize the main contactor. When an E-STOP command is given, the drive coasts to a standstill.

The E-STOP function can be triggered by one of the following methods:

  • Switch operation: E-STOP is activated when the switch between terminals 105 and 106 opens.
  • Pushbutton operation: Opening an NC contact between terminals 106 and 107 triggers the E-STOP function and stores the shutdown operation. Closing an NO contact between terminals 106 and 108 resets the function.

When the E-STOP function is reset, the drive switches to the “Starting lockout” state. This status needs to be acknowledged through activation of the “Shutdown” function, e.g. by opening terminal 37.

Note: The E-STOP function is not an

EMERGENCY STOP function according to

EN 60204-1.

Serial interfaces

The following serial interfaces are available:

  • One serial interface on connector X300 on the PMU for a USS protocol to the RS 232 or RS 485 standard. For connection of optional OP1S operator panel or for PC-based DriveMonitor.
  • One serial interface at terminals of the basic electronics board, two-wire or four-wire RS485 for USS protocol or peer-to-peer connection.
  • One serial interface at terminals of the terminal expansion board (option), two-wire or four-wire RS485 for USS protocol or peer-to-peer connection.
  • PROFIBUS-DP on a supplementary card (option).
  • SIMOLINK® on a supplementary card (optional) with fiber-optic connection.

Physical characteristics of interfaces

RS 232: ±12 V interface for point-to-point operation.

RS 485: 5 V normal mode interface, noise-proof, for an additional bus connection with a maximum of 31 bus nodes.

USS protocol

Disclosed SIEMENS protocol, easy to program on external systems, e.g. on a PC, any master interfaces can be used. The drives operate as slaves on a master. The drives are selected via a slave number.

The following data can be exchanged via the USS protocol:

PKW data for writing and reading parameters.

PZD data (process data) such as control words, setpoints, status words, actual values.

Connector numbers are entered in parameters to select the transmit data (actual values), the receive data (setpoints) represent connector numbers that can be programmed to act at any intervention points.

Peer-to-peer protocol

The peer-to-peer protocol is used to link one converter to another. With this mode, data are exchanged between converters, e.g. to build a setpoint cascade, via a serial interface. Since a serial interface is employed as a four-wire line, it is possible to receive data from the upstream converter, condition them (e.g. through multiplicative weighting) and then send them to the downstream converter. Only one serial interface is used for the whole operation.

The following data can be exchanged between converters:

  • Transmission of control words and actual values.
  • Receipt of status words and setpoints.

Up to five data words are transmitted in each direction. Data are exchanged on the basis of connector numbers and intervention points.

The serial interfaces can be operated simultaneously. For example, the first interface can be used as an automation link (USS protocol) for open-loop control, diagnostics and specification of the master setpoint. A second interface operates in conjunction with the peer-to-peer protocol to act as a setpoint cascade.

Control terminal block

Terminals on microprocessor board (basic electronics)

Connectors on PMU simple operator panel

  • P10 reference voltage, 10 mA load rating
    N10 reference voltage, 10 mA load rating
  • X300 connector for OP1S, RS 232 or RS 485 connection two-wire, max. 187.5 kBd
  • 2 analog inputs via differential amplifiers,
    resolution can be set between 10 to ± 14 Bit
    0 to ±10 V, 0 to ±20 mA, 4 to 20 mA

Terminals on gating board

  • 1 analog input für for motor temperature sensor using PTC or KTY84
  • Analog tachometer 8 to 250 V for maximum speed
  • Realtime analog output to ground for actual current, 5 V for rated converter current, max. 2 mA
  • E-STOP
  • 2 analog outputs to ground, 0 to ±10 V, ±11 bit resolution, max. 2 mA

Terminals on optional terminal expansion board

  • Pulse encoder evaluation für 5 or 24 V encoder,
    2 tracks and zero mark, maximum frequency 300 kHz
  • 4 binary selectable inputs via optocouplers, can also be used as interface to motor
  • P15 power supply, 200 mA for pulse encoder
  • 4 binary selectable inputs to ground
  • 4 binary inputs to ground,
    2 with selectable function
  • 2 analog inputs to ground, ±10 bit resolution
  • 2 binary outputs to ground, P24 open emitter, 100 mA load rating
  • 1 analog input for evaluation of motor temperature via PTC or KTY84
  • 1 serial interface, RS 485 two-wire or four-wire, max. 187.5 kBd
  • 2 P24 binary inputs to ground, open emitter, 100 mA load rating
  • P24 power supply for driving binary inputs
  • 2 analog outputs to ground, ±10 V, 2 mA load rating, ±11-bit resolution
  • 9 terminals for converter ground
  • 1 serial interface, two-wire and four-wire
    RS 485, max. 187.5 kbd
  • 1 parallel interface (2 connectors) for parallel connection of SIMOREG
  • P24 power supply for driving binary inputs
  • 8 terminals for converter ground


Closed-loop functions in armature circuit

Speed setpoint

The source for the speed setpoint and additional setpoints can be freely selected through parameter settings, i.e. the setpoint source can be programmed as:

  • Analog values
  • 0 to ±10 V, 0 to ±20 mA,
  • 4 to 20 mA
  • Integrated motorized potentiometer
  • Binectors with functions: Fixed setpoint, inch, crawl
  • Serial interfaces on basic unit
  • Supplementary boards

The normalization is such that 100 % setpoint (product of main setpoint and additional setpoints) corresponds to the maximum motor speed.

The speed setpoint can be limited to a minimum or maximum value by means of a parameter setting or connector. Furthermore, “adding points” are included in the software to allow, for example, additional setpoints to be injected before or after the ramp-function generator. The “setpoint enable” function can be selected with a binector. After smoothing by a parameterizable filter (PT1 element), the total setpoint is transferred to the setpoint input of the speed controller. The ramp-function generator is effective at the same time.

Actual speed value

One of four sources can be selected as the actual speed signal.

  • Analog tachometer.
    The voltage of the tacho-generator at maximum speed can be between 8 and 250 V. The voltage/maximum speed normalization is set in a parameter.
  • Pulse encoder
    The type of pulse encoder, the number of marks per revolution and the maximum speed are set via parameters. The evaluation electronics are capable of processing enco-der signals (symmetrical: With additional inverted track or asymmetrical: Referred to ground) up to a maximum differential voltage of 27 V.The rated voltage range (5 V or 15 V) for the encoder is set in a parameter. With a rated voltage of 15 V, the SIMOREG converter can supply the voltage for the pulse encoder. 5 V encoders require an external supply. The pulse encoder is evaluated on the basis of three tracks: track 1, track 2 and zero marker. Pulse encoders without a zero marker may also be installed. The zero marker allows an actual position to be acquired. The maximum frequency of the encoder signals must not exceed 300 kHz. Pulse encoders with at least 1024 pulses per revolution are recommended (to ensure smooth running at low speeds).
  • Operation without tachometer and with closed-loop e.m.f. control
    No actual value sensor is needed if the closed-loop e.m.f. control function is employed. Instead, the converter output voltage is measured in the SIMOREG. The measured armature voltage is compensated by the internal voltage drop in the motor (I*R compensation). The degree of compensation is automatically determined during the current controller optimization run. The accuracy of this control method is determined by the temperature-dependent change in resistance in the motor armature circuit and equals approximately 5 %. In order to achieve greater accuracy, it is advisable to repeat the current controller optimization run when the motor is warm. Closed-loop e.m.f. control can be employed if the accuracy requirements are not particu-larly high, if there is no possibi-lity of installing an encoder and if the motor is operated in the armature voltage control range.Important: The drive cannot be operated in e.m.f.-depen-dent field-weakening mode when this control method is employed.
  • Freely selectable actual speed signal
    Any connector number can be selected as the actual speed signal for this operating mode. This setting is selected in most cases if the actual speed sensor is implemented on a technological supplementary board.
    Before the actual speed value is transferred to the speed controller, it can be smoothed by means of a parameterizable smoothing (PT1 element) and two adjustable band filters. The band filters are used mainly to filter out resonant frequencies caused by mechanical resonance. The resonant frequency and the filter quality can be selected.

Ramp-function generator

The ramp-function generator converts the specified setpoint after a step change into a setpoint signal that changes constantly over time. Ramp-up and ramp-down times can be set independently of one another. The ramp-function generator also features a lower and upper transition rounding (jerk limitation) which take effect at the beginning and end of the ramp time respectively. All time settings for the ramp-function generator are mutually independent.Three parameter sets are provided for the ramp-function generator times. These can be selected via binary selectable inputs or a serial interface (via binectors). The generator parameters can be switched over while the drive is in operation. The value of parameter set 1 can also be weighted multiplicatively via a connector (to change generator data by means of a connector). When ramp-function generator time settings of zero are entered, the speed setpoint is applied directly to the speed controller.

Speed controller

The speed controller compares the speed setpoint and actual value and if these two quantities deviate, it applies a correspon-ding current setpoint to the current controller (operating principle: Closed-loop speed control with subordinate current controller). The speed controller is a PI controller with an additional selectable D component. A switchable speed droop can also be parameterized. All controller characteristics can be set independently of one another. The value of Kp (gain) can be adapted as the function of a connector signal (external or internal).

The P gain of the speed controller can be adapted as a function of actual speed, actual current, setpoint/actual value deviation or winding diameter. To achieve a better dynamic response in the speed control loop, a feedforward control function can be applied. For this purpose, a torque setpoint quantity can be added after the speed controller as a function of friction or drive moment of inertia. The friction and moment of inertia compensation values can be calculated in an automatic optimization run.

The output quantity of the speed controller directly after enabling can be set via a parameter.

Depending on how parameters are set, the speed controller can be bypassed and the converter can be operated under torque or current control. Furthermore, it is possible to switch between closed-loop speed control and closed-loop torque control in operation by means of the selection function “master/slave switchover”. The function can be selected as a binector via a binary assignable-function terminal or a serial interface. The torque setpoint is applied by means of a selectable connector and can thus be supplied by an analog assignable-function terminal or a serial interface.

In “slave drive” operation (under torque or current control), a limiting controller is operating. It can intervene on the basis of an adjustable, parameterized speed limit in order to prevent the drive from accelerating too far. In this case, the drive is limited to an adjustable speed deviation.

Torque limitation

Depending on parameterization, the speed controller output acts as either the torque setpoint or current setpoint. In closed-loop torque control mode, the speed controller output is weighted with machine flux φ and then transferred as a current setpoint to the current limitation. Torque-control mode is usually used in conjunction with field weakening so that the maximum motor torque can be limited independently of speed.

The following functions are available:

  • Independent setting of positive and negative torque limits via parameters.
  • Switchover of torque limit via a binector as a function of a parameterizable changeover speed.
  • Free input of torque limit by means of a connector, e.g. via an analog input or serial interface.

The lowest input quantity is always applied as the current torque limit. Additional torque setpoints can be added after the torque limit.

Current limitation

The purpose of the current limitation set after the torque limit is to protect the converter and motor. The lowest input quantity is always applied as the current limit.

The following current limit values can be set:

Independent setting of positive and negative current limits via parameters (setting of maximum motor current).

  • Free input of current limit by means of a connector, e.g. via an analog input or serial interface.
  • Separate setting of current limit via parameters for shutdown and fast stop.
  • Speed-dependent current limitation: Parameters can be set to implement an automatically triggered speed-dependent reduction in the current limitation at high speeds (commutation limit curve of motor).
  • I2monitoring of the power section: The temperature of the thyristors is calculated for all current values. When the thyristor limit temperature is reached, the converter current is either reduced to rated DC current or the converter is shut down with a fault message, depending on how the appropriate response parameter is set. This function is provided to protect the thyristors.

Current controller

The current controller is a PI controller with mutually independent P gain and reset time settings. The P or I component can also be deactivated (to obtain a pure P controller or a pure I controller). The actual current is acquired on the three-phase AC side by means of current transformers and applied to the current controller after A/D conversion via a resistive load and a rectifying circuit. The resolution is 10 bits for converter rated current. The current limiting output is applied as the current setpoint.

The current controller output transfers the firing angle to the gating unit, the feedforward control function acts in parallel.

Feedforward control

The feedforward control function in the current control loop improves the dynamic response of the control. This allows rise times of between 6 and 9 ms to be achieved in the current control loop. The feedforward control operates as a function of the current setpoint and motor e.m.f. and ensures that the necessary firing angle is transferred speedily to the gating unit in both intermittent and continuous DC operation or when the torque direction is reversed.

Auto-reversing module

The auto-reversing module (only on converters for four-quadrant drives) acts in conjunction with the current control loop to define the logical sequence of all processes required to reverse the torque direction. One torque direction can be disabled by a parameter setting if necessary.

Gating unit

The gating unit generates the gate pulses for the power section thyristors in synchronism with the line voltage. Synchronization is implemented independently of the rotating field and electronics supply and is measured on the power section. The gating pulse position timing is determined by the output values of the current controller and feedforward control. The firing angle setting limit can be set in a parameter.