The task set in the requirements specification of Messrs. Baumüller at Bad Gandersheim was to present a production supporting a test concept for DSD-servo motors. Messrs. Baumüller, with their headquarters in Nuremberg, and propulsion technique are a world-wide synonym concerning their competence in this area.

 

Among their customers are many well-known companies from the printing, textile and machine tool industry. DSD motors are applied wherever enormous moments of acceleration occur simultaneously with the highest requirements in dynamics. Included in the test concept are surge voltage, inductance-resistance and high voltage tests. With the function tests transmitter signals are, among others, recorded, noise analyses are performed and DUT specific constants are evaluated.

 

The advantage of such a production supporting concept is quite obvious. Weakness in material is already detected at an early stage in the production process. Therefore all of the operations that follow next will be all the more efficient because the rate in errors will be lower.

Included in this concept are three single stations placed separately connected via the Ethernet with each other. The test results of the PC-controlled systems are filed in a central ACCESS data bank. The DUT specific serial number does, individually, represent, so to say, the "bridge" between the test stations. The surge voltage test is the initial test. The DUT is placed into a special adapter and contacted. Via the read-in of a barcode the respective programme is loaded automatically and a new data record is created. The result is filed in the data bank under the scanned-in production number. Later on in the production process an inductance and resistance test will be performed at the potted stator. The inductance test is performed with the DU 6000 and the resistance measurement is performed with the DU 5000, both are testers of the SPS electronic company.

 

The DUT has to be contacted only once due to a freely connectable matrix. Here, too, the programme is started by scanning-in the production number. If a data record is not yet available or the result of the previous surge voltage test is faulty a respective message is displayed or edited. It is, however, the end test which is the really complex part. The safety relevant tests as well as the function tests are the important ones in the final testing.

 

The SPS electronic safety tester S3301 is the basis for these safety tests. The protective wire, insulation and high voltage tests are performed acc. to standard with this tester. The test potentials can all be freely selected via the software. The DUT is fixed in the test enclosure onto a variable adapter. Thus the connections for the protective wires and the body sound test are made automatically. By closing the test enclosure the freely programmable programme process is started.

 

DSD motors require special controls supporting the various transmitter signals. Here three (3) controls of Messrs. Baumüller have been applied which, among others, support the SinCos, resolver and different incremental transmitters. The real problem of the function test is based on the intelligence of the control. Same can be configurated with up to 1000 parameters. As each motor needs a different parameter record an actually appropriate function test could not be selected.

The solution is to be found in the macro software 3332DAT. Macro steps are small test programmes allowing the customer direct access to the under-most control level. These steps can be created easily via a macro editor by the customer and are inserted as test step into the test programme.

 

In a macro editor one can, similar to a programming language, define variables, perform loops and execute evaluations. Access to the I/O level allows the setting / resetting of digital outputs. Analogue inputs can be read and assigned to variables. Due to the access to serial interfaces the controls can be configurated DUT specifically. Parameters which are often used are stored in a file. During the macro tests parameters can again be read from the controls and be used for evaluations.

The transmitter signals of the servo motors inform the controls where and at which velocity the rotor is positioned in the stator. In the test system the signal patterns of up to four (4) transmitter signals can be stored and evaluated via special oscilloscope terminals. The values of the transmitter signals are recorded via a relay matrix. While the motor is slowing down the induced voltage of the DSD motors is measured. With the respective formulas and no-load currents the EMF and the friction torque are evaluated in this macro step. At the same time the body sound can be recorded and evaluated via a special measuring instrument. With each step the value which has been recorded / evaluated can be filed under the scanned-in production number in the data bank. Due to this macro software the customer is almost completely independent of the producer of the system and is able to create or alter macro steps himself.

In co-operation with the user a test concept has been designed which will detect defects without fault throughout the process of production up to the end test. The modular design of the systems and the variable macro software will prepare the customer well for the future.

Download Leaflet "Test system for DSD servo motors", PDF-file (approx. 225 KB)