MTS Systems MPA-460 Servo Drive

[billbrwn]

Looking for information on an MTS Systems MPA-460 Servo Drive It is a brushless servo amplifier used on a line shearing machine. I don't have the manual anymore and I'm hoping someone has info and experience on these MTS amplifiers.

It was made in a few sizes:

• MPA-05-460 - 5 amp size
• MPA-10-460 - 10 amp size
• MPA-15-460 - 15 amp size
• MPA-25-460 - 25 amp size
• MPA-35-460 - 35 amp size
• MPA-50-460 - 50 amp size
• MPA-75-460 - 75 amp size
• MPA-100-460 - 100 amp size

Thank You!

[3rdshiftguy]

Looking for information on an MTS Systems MPA-460 Servo Drive

What kind of info are you looking for exactly? Drive Troubleshooting? Drive Setup and Tuning?

[billbrwn]

Looking for information on an MTS Systems MPA-460 Servo Drive

What kind of info are you looking for exactly? Drive Troubleshooting? Drive Setup and Tuning?

Pretty much all of the above. I recently purchased a used piece of equipment and the MTS drive appears to be a weak link. They supplied me with an extra drive and I have already had this one fault out on overcurrent. I had to let it cool off before it would work again.

I'd like to check the setup and see what I can do to troubleshoot the issue.

[benklassne]

I've compiled some information from the manual here. This may help you with the setup and troubleshooting of your drive.



Introduction:

MPA Amplifiers represent a series of amplifiers that are high performance, reliable, and efficient. The amplifiers are designed to be used with high performance brushless servo motors.  Extreme care has been taken to assure robust operation. Design consideration for electrical transients have been implemented on the ac inputs and all I/O lines.

MPA amplifiers operate over ac voltage ranges of 200 to 520 Vac from 45 to 65 Hz. The motor feedback device is a resolver to assure normal operation at elevated motor temperatures of 115° C for the case, and 155° C for the motor windings.

The resolver allows for both position and velocity feedback. The motor is further protected by a thermal shutdown thermostat in the motor windings. The amplifier high power switching devices are state of the art IGBT modules. The logic supplies are switch mode designs reducing undesired heat. LED indicators for diagnostics are provided.

Encoder simulated TTL compatible differential quadrature outputs plus an index output are provided for external pulse or position control. The amplifiers have inrush current protection to allow for normal turn on. This is especially worthwhile for multiple-axis applications. Consideration for dissipation of regenerative energy is included with internal shunt regulators.

Feedback Wiring:

100% shielded cable is foil and braid. The pairs do not have to be twisted. The resolver wiring should not be run adjacent to any non-shielded high voltage wires, such as the motor wires (RST). If the wiring cannot be separated, the RST motor leads should also be 100% shielded. It is highly recommended that factory cable sets or wiring be provided.

Thermostat:

If the motor is equipped with a winding thermostat that is normally closed, it can be connected between terminals 7 and 8 of the feedback wiring connector. If an excess temperature thermal condition exists as indicated by an open thermostat, the amplifier is disabled.

Motors and Commutation:

The amplifier can commutate 4-pole, 6-pole, 8-pole, and brush motors in its standard configuration and other factory options are available. DIP switch S2 allows for configuration changes and switches one and two determine the choice. Amplifiers are shipped set for 6-pole operation. Never change the switch settings of S2 with power ON.

All MTS Automation two-inch motors are 4-pole. The three-inch, four-inch, six-inch, and eight-inch motors are 6-pole motors. For brush motor operation, no resolver alignment is required and the R lead connects to armature (+) and the T lead connects to armature (-). These connections will cause clockwise rotation from the shaft end of the motor.

Diagnostic Indicators

Mark (RED): This is an output that comes ON at the resolver zero position and can be used in conjunction with alignment procedures. The zero position is about .5 degrees.

Current (BI-COLOR): This is a bi-color LED that can be either red or green as a function of load. Red indicates positive torque and green indicates negative torque. The intensity increases with load.

Power (GREEN): If logic +5 Vdc is ON, then this LED is ON.


Fault Analysis:

There are eight faults that will disable the amplifier, they are indiciated by LED:

CONTINUOUS - If a load condition exists that causes the amplifier to produce more than its continuous rating, this fault occurs.

STATOR SHORTS - If stator shorts or most major wiring errors of the stator occur, this fault occurs.

AMPLIFIER THERMAL - An 85° C thermostat is mounted to the amplifier's IGBT heat sink. If an excess temperature is sensed, this fault occurs.

FEEDBACK WIRING - For most resolver wiring errors, defective resolvers or tracking rate errors caused by the resolver, this fault occurs.

MOTOR THERMAL or OVERSPEED - If an excess thermal or adjustable condition exists in the motor, this fault occurs.

HI-BUS - If excess DC voltage or a failure of the shunt circuit occurs, this fault occurs.

RESET - During the first second of power up or if the reset input is active, this LED will be ON.

LIMIT - If either of the limit inputs are ON, This LED will be ON.

[billbrwn]

Thanks, that's what I'm looking for!

Do you have setup procedures also. In other words, how to setup the drive from scratch.

[benklassne]

Here is more info that relates to the wiring an IO details. I will post the drive setup information later due to time constraints but this should be a big help if you are configuring one of the MTS drives from scratch.



Simulated Encoder Signals

For external counting or position control, a 9-pin D type female connector that has TTL complimentary outputs is provided. This simulates quadrature encoder channel A and channel B signals. A differential mark signal is also available.

These signals are RS422 compatible. There are two jumpers that determine the resolution of the simulated encoder signals (JP1 and JP2). The normal factory configuration of 2-Channel quadrature provides for output resolution of 12 bits or 4096 counts per revolution. 14 bit resolution can be ordered by specifying a "-14" after the selected MPA amplifier (eg. MPA-09-460-14). With the "-14" option, the jumper configurations are as follows. The maximum 2-Channel resolution with quadrature channels in this mode is 16,384. The maximum tracking rate of the amplifier is limited to 60 rps or 3600 rpm with the "-14" option.

SIMULATED ENCODER

DIP switch S3 switches 1,2,3, and 4, are used for this purpose. By setting switch 2 to the OFF position, the operation of the + LIMIT would change to be closed to run in a plus direction. This reversing characteristic is true for all four switches.

There is a FAULT output. This is equivalent to an open collector NPN transistor with its emitter connected to GND. This transistor can sink 2 amps and it can withstand 110 volts dc when OFF. When a fault occurs, this output turns ON.

This output can also have its polarity inverted by switching the fourth switch on DIP switch S2. Once this is done, this output will be ON if no fault exists. This output would now be thought of as a READY output instead of a FAULT output.

The normal fault operation occurs with S2-4 ON. The purpose of inversion of this output is to allow for direct connection to fail safe brakes or other brake interlock circuits.

If this inverted output is used, consideration for the Power-Up Reset Input may be required. For example, during power-up a reset would disable faults. This same reset may then defeat the desired operation of the brake.

With no faults and an inverted output selected, the brake output would be ON but power would not be applied to the motor. If the JR1 shorting pin is installed then a Reset/Disable condition is allowed to keep the output ON even though there is no fault.

I/O Wiring and Descriptions

The amplifier has four inputs and one output. These inputs and output are designed to interface to a 24 volt logic system. The amplifier is shipped so that the operation of the inputs is as follows.



With no wires connected to RESET, + LIMIT, - LIMIT, or VELATORQUE, the amplifier is enabled and normal operation will occur in a velocity mode. The inputs are activated by connecting them with a switch closure to any of the provided GND terminals.

The VAT is an input that determines the amplifier mode, Velocity/Torque mode. When the switch is open, the Velocity mode is selected. When the switch is closed, the Torque mode is selected.
As the polarity of the inputs may vary depending on the application, a DIP switch is provided to allow for an inversion of the function.

Resolver Converter Resolution

These jumpers determine the 12 or 14-bit mode. Unless specified, all amplifiers are preset for 12-bit mode. JSC1 and JSC2 determine the R-Digital resolution. JB1 and JB2 determine the origin of the signals for the encoder simulation; When they are DOWN (2-3), the encoder simulation is based on the two LSD's of the 14 bit mode.

The encoder simulation jumpers JP1 and JP2 must also be IN. The line resolution is fixed at 4096 lines per channel. With the JB1 and JB2 jumpers in the UP (1-2) position, the two LSD's from the 12 bit mode are used for the encoder simulation and the JP1 and JP2 jumpers are used to alter the choices of the 12 bit mode.

When the R-D converter is configured for 14 bit mode, JB1 and JB2 can be placed in the UP (1 -2) position to allow for other encoder selection besides the normal 4096 lines per channel. Changing to 14-bit mode cannot be accomplished as a user option on a standard amplifier. The -14 option must be provided.

Analog Inputs, Outputs and Adjustments

Inputs: There are two analog input channels; one for command and one for auxiliary. Both of these channels are differential inputs and both are summed with a TAG feedback differential amplifier that controls velocity.

Normal operation of the command signal is to apply a + voltage (pin #9) with respect to GND(pin #11) and get clockwise rotation of the shaft. ±10 volts is then used to control velocity and the SIG pot is used for velocity adjustments. If the + COMMAND voltage is applied to the - COMMAND signal input, then an opposite shaft rotation occurs.

The operation of the AUXILIARY ± inputs is the same as the COMMAND inputs. The normal purpose of the AUXILIARY inputs is to provide a second summing voltage to compensate/modify normal COMMAND voltage.

If the input for VEL/TORQUE is active and a torque mode is chosen then voltages applied to the COMMAND ± inputs control motor current. The SIG pot can now be used to adjust the amount. Normal operation in this mode assumes that 10 voits is peak current and 5 volts is the continuous current rating of the amplifier.

The current limit of the amplifier can be adjusted with the CUR pot from 0 (full CCW) to 100% (peak full CW). It is a good idea during start-up to adjust the CUR pot to its full CCW position and increase it slowly CW to assure normal operation.

During start-up the BAL adjustment can be used to reduce/stop any low speed CW/CCW drift caused by imbalance between the external command voltage and the amplifier.

Once connected to loads, the crispness of motion (step response) and stability can be optimized with the RESP and LEAD pots. Full CW is maximum response and full CCW is minimum LEAD. The location of these adjustments is next to the I/O wiring.

Outputs: Two diagnostic outputs are the dc voltage proportional to velocity and the dc output proportional to current/torque. The nominal TAG gradient is 1.3 volts per thousand rpm. The current gradient is 10 volts equal peak.

Analog Inputs and Specific Interface Requirements

The analog input channels consist of differential input amplifiers to allow controllers that have differential output drivers a three wire connection that excludes potential ground loops. When differential modes of operation are used, the command or auxiliary input is based on 5 volts equaling maximum input and the analog ground from the external controller must be connected to the MPA drives GND connection.

A +5 volt connection to the COM+ terminal and a -5 volt connection to the COM- terminal is equal to a + 10 volts command voltage. The rotational direction of the motor will be CW viewed from the shaft end of the motor. To change directional rotation the COM+ and COM- connections must be reversed.

The most typical input to the command and auxiliary inputs is a simple two wire interface consisting of a command voltage with respect to a GND. The ground wire of this pair must be connected to the MPA GND terminal associated with the analog channel, and the command wire can be connected to either the COM+ or COM- input to determine the rotational characteristic required.

A positive command voltage with respect to GND connected to the COM+ terminal will cause CW rotation as viewed from the shaft end of the motor. The unused input, COM+ or COM-, should be connected to GND.

TAG Gradient, Response, Lead

The control board for these amplifiers has jumpers that allow for various configurations of compensation and filter networks. The physical location of these jumpers is indicated on this figure.

Jumper Configurations

Lag Network-JL1  JL2: The JL1, JL2 jumpers and the (RESP) pot adjustment affect operation of the PID Loop's Term. The JL1 jumper varies the integration capacitor. The JL2 jumper varies the integration resistor.

The maximum integration occurs with the RESP pot full CCW. CW adjustment decreases integration, usually to a point of not being stable.

The maximum tracking rate of the resolver to digital converter in the 12-bit mode is 200 rps and is 60 rps in the 14-bit mode.

TACFilter-JF1: With JF1 IN the TAC filter is maximum and with it OUT the TAC filter is minimum. For smaller motors minimal TAC filtering improves response.

[benklassne]

This is information relating to the setup of the drive. The procedure from the manual isn't the greatest but this is what they have.

Set-Up

This procedure assumes that the amplifier is being used in the velocity mode otherwise the external controller would resolve PID gains for the amplifier and the amplifier would be in the TORQUE mode.

The USER adjustments are set as follows for shipping:

• LEAD- Full CCW (no lead)
• SIG - MID
• RESP - MID
• CUR - MID
• BAL - MID

The procedure that is used to determine the actual SWITCH settings and USER adjustments is load and application dependent.

The best method to determine these is based on testing with Voltmeters and Oscilloscope for observing the TAG and command signal. P (proportional gain) is determined by the TAG and signal gains.

An oscilloscope can be used to monitor the TAG signal for over or under damping. The I (integral gain) is controlled by the RESP pot and the jumper settings of JL1 and JL2. The D (derivative gain) is determined by the adjustment of the LEAD pot.

An abbreviated method that allows for reasonable success is:

• Determine the TAG gain for the application and set the JG1, 2, 3, and 4 jumpers accordingly. Amplifier saturation is based on 10 volts of either signal or TAG. With the TAG jumpers set for normal operation, the TAG gradient is 2.7 volts per thousand and saturation will occur at 10 volts max / 2.7 volts per Krpm = 3.7 Krpm. The motor's KE, and the amplifier's bus voltage will also limit the maximum speed.
  
  The amount of TAG gain alters the drive's proportional gain, and under most conditions higher TAG gains allow control of larger inertia. Since TAG gain compared to signal gain also controls velocity, the external controller's dc voltage proportional to velocity is an issue to consider. In some controllers a KF (feedforward term) is available. This term is a pre-computed voltage that is the velocity component.
  
  The controller's KP term adds or subtracts from this existing KF term, based on encoder count error, a voltage that forces correction. For this type of controller, the best possible performance can be achieved by having high TAG gain and minimum KP. Following errors are adjusted out with the drive's SIG adjustment when running at a known speed, and the BAL adjustment can be used to zero following error at zero velocity.
  
  Some controllers have no KF term and run error loops. Motion occurs as a result of the error over time, and for each time interval more error occurs causing higher speed. For this type of control, high TAG gains would generally deteriorate performance as the key to running is to make the same following errors at the same times.
  
  This type of control is very common. In several instances the difficulty in setup is that the external controller has no KP or KF term and the drive's KP is the only way of achieving stability. The drive's KP is determined by the TAG gain, SIG/AUX pot, LEAD pot. The best process would be to start out with the lowest TAG gain. Adjustment of the SIG/AUX input, RESP, and LEAD should cause normal operation.
• The TAG filter jumper JF1 is usually IN (maximum filter). Removing JF1 decreases the filtering and is primarily intended to accommodate the brushless TAG option. In very fast applications, removing JF1 can improve bandwidth, but it depends on load conditions and various sized motors.
  Reducing filtering also leads to more audible noise. JL1 and JL2 should be IN for maximum integration, (I)
• We would next set the RESP and CUR pots full CCW and assure that the
  LEAD pot is full CCW. The BAL pot and SIG pot are in the MID.
• Power up the amplifier.
• Slowly turn the CUR pot towards the middle position while observing the
  following.
  a. it may be necessary to increase the RESP adjustment to achieve
  stability or to minimize oscillation or vibration.
  b. if the instability is substantially improved but not good enough, the
  LEAD adjustment can be increased.
• If operation is improved but not good enough, the process can be repeated
  from Step 3 after removing JL1. This decreases integration.
• If operation is again improved but still not good enough, the process can be
  repeated from Step 3 after removing JL2. This increases gain.
• If you are unable to achieve the speed you want, you may have to increase
  the SIG pot to have an 8-10 volt command signal equal the amplifiers
  maximum velocity.
• You can also continue to increase the CUR adjust as operation is improved.

[benklassne]

As a note, we had issues with tuning on one of our drives and we fixed using external inductors that were supplied by MTS. External inductors were recommended from the beginning of the project and we decided to forgo them at first. We ended up adding them into the application eventually.

This is the section regarding external inductors that are optional to the MTS MPA drives.

External Inductors

External inductors can be placed in the amplifier R, S and T leads to assure that the minimum inductance specification is assured. The MPA-05/09/15 models all have 2mH drum core inductors installed under the top cover. These versions do not need external inductors to protect the motor. For the MPA-24/35/50/75/100 models, the inductance line-to-line must be no less than 4mH.

One inductor in each line is typical. The turn ON times of the power switches can cause catastrophic destruction of motors. Inductors in RST of the motor leads limit the rise time and preserve the motor.

All 460 volt motors should have inductors. Since the inductors can become very hot, it is recommended that they be wired external to the amplifier enclosure.

[benklassne]

Here's more info on the MTS MPA drives that is helpful. The startup procedure in the manual is very brief, it seems like you are assumed to know alot about drive setup and startup.

Here's what they have in the manual regarding startup:

Start-Up
Once normal wiring is verified, power can be applied to the amplifier.

Assure the DIP switch and jumpers are set as required. Default settings are for 6 pole motors on most MPA amplifiers; 4 pole motors on the MPA-05. Inputs Reset, +Limit, and -Limit are not going to disable the amplifier if they are not connected.

Never change the settings of DIP switch 2 with power ON.

The CUR and RESP adjustments are turned down (CCW). CUR is 50% and RESP is minimal.
It is recommended that CUR be turned to its full CCW position. Once power is applied, CUR can be slowly increased in a CW direction to achieve shaft torque. Crispness can be increased by a CW adjustment of RESP.

For start-up verification of wiring with external position controls the following simple test can be used to verify the phase relationship.

With the current limit turned full CCW or with the RST wiring disconnected, a CW rotation of the motor shaft will produce a negative command voltage at pin #9 (SIG) to pin #11 (GND) on the I/O (J1) connector. For a CCW rotation, a positive command must occur.

The rotation is started from a null, or a close to zero shaft position. If the relationship is wrong, there are two choices: interchange the A, A\ and B, B\ signals at the simulated encoder.
use the command - input for signal and pin #11 is still ground.

Either method works, but the first method still assures that positive command voltages cause CW rotation of the motor shaft as viewed from the shaft end of the motor.

Good Luck with your drive setup, hope this helps you out!

[billbrwn]

Nice job on the post, there's enough info here to do a drive install and setup right out of the box. Good Stuff!