Bonfiglioli Vectron EM-RES-01 Expansion Module Rotary Transformer Interface Configuration Guide



Bonfiglioli Vectron EM-RES-01 Expansion Module Rotary Transformer Interface Configuration Guide

In the field of industrial servo drive and synchronous motor control, precise detection of rotor position is the core prerequisite for ensuring efficient and smooth operation of motors. Although incremental encoders are widely used, their reliability often faces severe challenges in harsh environments such as high temperature, vibration, and oil pollution. As an electromagnetic position sensor, the rotary transformer (Resolver) has become the preferred feedback solution for heavy-duty servo and permanent magnet synchronous motor (PMSM) control due to its durability, anti pollution, and high temperature resistance.

The Bonfiglioli Vectron ACTION and ACTION Cube series frequency converters have introduced a rotary transformer interface through the EM-RES-01 expansion module for drive systems that originally only supported incremental encoders, while retaining analog input and CAN system bus functions, making standard frequency converters capable of high-precision and high reliability synchronous motor control applications.

Overview and Functional Positioning of EM-RES-01 Expansion Module

1.1 Module Core Functions

EM-RES-01 is an optional hardware expansion component designed by Bonfiglioli Vectron for the ACTION and ACTION Cube series frequency converters, supporting software versions 4.1.0 and higher for the ACTION series and all ACU series devices. This module achieves the following functional extensions by inserting it into the lower expansion slot of the frequency converter:

CAN system bus interface: compliant with ISO-DIS 11898 (CAN High Speed) standard, supporting a maximum communication rate of 1 MBaud

Resolver Interface: Excitation voltage output and SIN/COS signal input

Analog input (EM-S1INA): 12 bit resolution, configurable for ± 10V voltage or ± 20mA current input

Repetitive frequency output (EM-RFOUT): Simulate the Resolver signal into an incremental encoder signal output (A+/A -/B+/B -)

1.2 Positioning Differences between EM-IO Series and EM-RES-01

Functions EM-IO-01~04 EM-RES-01

CAN system bus support

Analog input support (1 channel) Support (1 channel)

Digital input/output support not supported

Analog output support (some models) not supported

Temperature monitoring (PTC/KTY) supported (02/03/04) not supported

The interface of the rotary transformer is not supported

Repetitive frequency output is not supported

Core value positioning: EM-RES-01 is a specialized extension module designed for closed-loop control of synchronous motors in the EM-IO series. It sacrifices universal I/O and integrates a complete rotary transformer interface, enabling standard ACTIVE/ACU frequency converters to drive permanent magnet synchronous motors and achieve high-precision speed and position control.

Technical specifications for rotary transformer interface

2.1 Electrical specifications

The rotary transformer interface of EM-RES-01 has the following key electrical parameters:

Parameter specification description

The excitation voltage (REF) 4V (effective value) is provided to the AC excitation of the primary winding of the rotary transformer

Excitation current Imax=60mA driving capability limit

SIN/COS input voltage 2V (effective value) feedback signal from the secondary winding of the rotary transformer

Input voltage withstand 30V overvoltage protection capability

Input impedance>95 Ω @ 5kHz/20kHz matched with rotary transformer

The maximum number of pole pairs is 24, which is suitable for multi pole rotating transformers

Maximum speed of 30000 rpm (pole pairs=1) High speed application capability

Phase offset of 7 ° (5kHz)/14 ° (10kHz)/26 ° (20kHz) varies with excitation frequency

2.2 Selection of Incentive Frequency

The excitation frequency of the rotary transformer can be selected through parameter 380 (Operation Mode):

Applicable scenarios for mode frequency

5 5 kHz long line transmission, low-speed application

10 kHz universal recommended settings

High speed applications with 20 kHz and low latency requirements

Selection tip: The selection of excitation frequency should take into account the cable length, specifications of the rotary transformer, and the maximum speed of the motor. The higher the frequency, the faster the signal update rate, but the greater the cable attenuation and phase shift.

2.3 Matching of pole pairs for rotary transformers

Parameter 381 (No. of Pole Pairs) is used to set the number of pole pairs for the rotary transformer, with a range of 1-24 and a factory value of 1.

Key constraint: For synchronous motor control, the ratio of the number of motor poles to the number of rotating transformer poles must be an integer. For example, a 4-pole pair motor paired with a 2-pole pair rotary transformer (ratio=2) is acceptable, but paired with a 3-pole pair rotary transformer (ratio=4/3) is not allowed. If the ratio is not an integer, the frequency converter will report fault F1423.

Wiring specifications for rotary transformers

3.1 Terminal Definition

The rotary transformer interface of EM-RES-01 is located at socket X410A (terminals 1-6):

Terminal signal description

X410A.1 REF+excitation signal positive pole

X410A. 2 REF - excitation signal negative pole

X410A.3 SIN - sine signal negative pole

X410A.4 SIN+sine signal positive pole

X410A.5 COS cosine signal negative pole

X410A.6 COS+cosine signal positive pole

3.2 Repetitive frequency output (simulated incremental encoder)

EM-RES-01 can convert the Resolver signal into an incremental encoder signal output for speed monitoring of external devices (such as PLC high-speed counting modules):

Terminal signal description

X410A.7 A+Track A positive pole

X410B. 1 A-Track A negative pole

X410B. 2 B+positive pole of track B

X410B. 3 B-Track B Negative

Specifications:

Maximum frequency: 512 kHz

Output type: TTL (push-pull), compliant with RS-422A/RS-485

Maximum output voltage: 5V

Maximum current: ± 60mA (minimum load resistance 150 Ω)

Fixed division mark: 1024 (no parameterization required)

3.3 Shielding and Wiring Requirements

To ensure signal integrity, the manual explicitly requires:

Use shielded twisted pair cables (SIN+paired with SIN -, COS+paired with COS -, two excitation wires paired)

The shielding layer is connected to the PE (protective earth) over a large area at both ends

Control and communication cables are physically separated from power cables

Offset setting of rotary transformer - core link of on-site debugging

The offset setting of the rotary transformer is the most critical and complex step in the on-site debugging of EM-RES-01. The accuracy of Offset directly affects the starting performance, smooth operation, and output torque of synchronous motors.

4.1 The Physical Meaning of Offset

In permanent magnet synchronous motors, there is a fixed angular deviation between the rotor position of the rotary transformer and the magnetic pole position of the motor rotor, known as Offset. This deviation is due to the mechanical installation position of the rotary transformer on the motor shaft. If the Offset is not accurate, the frequency converter will not be able to correctly determine the position of the rotor magnetic poles, resulting in:

The motor cannot start (only shaking without rotation)

Motor reversal or acceleration loss of control

Excessive current triggers overcurrent protection

Parameter 382 (Offset) is used to compensate for this deviation, with a range of -360.0 °~360.0 ° and a factory value of 0.0 °.

4.2 Safety Preparation Before Offset Setting

Before performing Offset tuning, the following security measures must be taken:

Release load coupling: If possible, disconnect the motor from the load machinery to ensure that the motor shaft can rotate freely.

Release mechanical brake: If the motor is equipped with a brake, ensure that it has been released.

Set frequency limit: Set parameter 417 (Switch Off Limit) to a lower value (such as 5-10Hz) to prevent motor runaway in case of Offset error.

Set current limit: Set parameter 728 (Current Limit) to about 10% of the rated current of the motor to prevent overcurrent when Offset error occurs.

Warning: If the load cannot be disconnected, make sure that the motor is running at low speed and will not cause equipment or personnel injury.

4.3 Data Input and Preliminary Verification

Exit automatic SETUP: When powered on for the first time, the operating unit displays "SETUP", press the ESC key to exit.

Input motor nameplate data: Enter the PARA menu and input the rated voltage, current, frequency, speed, and pole pairs of the motor (parameter 373).

Set the parameters of the rotary transformer:

Parameter 380=Select excitation frequency (e.g. 10kHz)

Parameter 381=Set the number of poles of the rotary transformer

Manually rotate the motor shaft: Rotate the motor shaft manually and observe the displayed value of parameter 219 (Frequency Speed Sensor 2).

When rotating clockwise, a positive value should be displayed.

If a negative value is displayed, swap the wiring of X410A.3 (SIN -) and X410A.4 (SIN+).

4.4 Offset coarse adjustment - judged based on motor behavior

Set a low speed setpoint (such as 10% below Switch Off Limit 417) and start the motor through digital input. Observe motor behavior:

Scenario 1: The motor does not rotate or only stops after shaking

Check if parameters 373 (motor pole pairs) and 381 (rotary transformer pole pairs) are correct.

If the parameters are correct, switch the wiring of any two phases of the motor (such as U and V), as the rotation direction of the motor and the rotating transformer do not match.

Power on again and try to start.

Scenario 2: Still not starting after exchanging phase lines

Increase Offset (parameter 382) by 90 °/motor pole pairs.

If it still does not start, switch the motor phases (such as U and W) again.

Scenario 3: Motor accelerates until frequency limit (runaway)

Check if there is an open circuit or poor contact in the wiring of the rotary transformer.

If the fault code is F1100 (overclocking), increase the Offset by 180 ° per motor pole pair.

4.5 Offset Fine Adjustment - Based on the Voltage Formed by Magnetic Flux

After the motor can run stably at the set speed, perform fine adjustment of Offset:

Observe the displayed value of parameter 235 (Flux Forming Voltage).

Adjust parameter 382 with a small step size (such as 2.5 °) and observe the change in 235:

If 235 is a positive value, increase Offset.

If 235 is a negative value, reduce Offset.

Repeat the adjustment until 235 approaches 0 (ideal target).

Recheck and fine tune Offset at 50% rated frequency.

Engineering tip: If there is no significant change in the value of 235 during the adjustment of Offset, it indicates that the step size is too small and should be increased (such as 10 °) and tried again. The maximum effective adjustment range of Offset is 360 °/(number of motor poles/number of rotating transformer poles).

4.6 Offset setting completed

After setting the offset:

Restore parameter 417 (Switch Off Limit) to the normal operating frequency limit.

Restore parameter 728 (Current Limit) to its rated value.

Perform SETUP guided debugging (allowing the frequency converter to automatically optimize the current loop parameters).

Please note: SETUP will reset some parameters, and after completion, it is necessary to confirm again whether Offset remains at the set value.

Analog input configuration

EM-RES-01 retains the same analog input functionality as the EM-IO series (EM-S1INA, located in X410B. 4):

Voltage/current switching: selected through dip switch S3

S3=OFF (downward): ± 10V voltage input

S3=ON (up): ± 20mA current input

Resolution: 12 bits

Characteristic curve: Set the two-point linear characteristic through parameters 564-567

Operation mode: Parameter 562 selects bipolar/unipolar/absolute value mode

Tolerance band: Parameter 560 (0%~25%, factory 2%) is used for zero crossing anti shake

Filtering: Parameter 561 selects a time constant of 0-5000ms

Analog input can be used as a frequency reference source, percentage reference source, or limit source.

Engineering application of repetitive frequency output

The repetition frequency output (EM-RFOUT) of EM-RES-01 converts the speed signal of the rotary transformer into an incremental encoder signal (A+/A -/B+/B -), which has the following engineering value:

PLC speed monitoring: The actual motor speed can be fed back to the PLC high-speed counting module without the need for an additional encoder

Master slave synchronization: serving as a speed reference source for the slave frequency converter

Diagnostic tool: Monitor the quality of the Resolver signal during debugging

Technical Specifications:

The division mark is fixed at 1024

Maximum output frequency 512kHz

TTL/RS-422 level, can be directly connected to standard differential encoder receiving equipment