Development of production test of hybrid car controller

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Dr. Fehér Béla
Department of Measurement and Information Systems

The power control unit is one of the most important parts of the hybrid car’s powertrain, which controls the electric drive and the charge of the batteries. It contains both robust power electronics and complicated control circuits, therefore sensitive, high-frequency signals and currents of more hundred Ampers with voltages of more hundred Volts are present as well.

The production of the unit is also complicated, has numerous possibilities of faults, so in more phases of the process test procedures are needed. The last one of them is the End of Line (EOL) test, it has to inspect the operation of the whole unit. It consists of testing the control functions, on the other hand measuring the level of the power conversions in various modes. Requirements of the test is the satisfying accuracy, the fast and at the same time stable run, and simple, cost-efficient set-up as well.

There is an existing test station to perform the task, but it doesn’t achieve the expectations completely, and the production ramp-up will need further equipments also. In my thesis I developed the improvement elements of the present and the future test stations.

Setting up the equipment I demonstrate a new, simplified method of the connection and switching of the existing instruments. In this, electromagnetically strongly disturbed environment I made a complete protection system against the disturbances to achieve more accurate and stable measurements.

The test program, which provides the run of the measurements, has to be reviewed as well. I present an overview of its structure, a system design, the function of each level, and the setup of a uniformed instrument control conception on more (serial, GPIB) control network. I demonstrate the low and high level instrument control devices of the LabWindows CVI environment.

Realizing two high-power measurements I present, why is important to set up the measuring conditions in the correct way, to avoid the unwanted effects of coming transient phenomena, which can cause mistaken results of some measurements. Finally I present a new method of testing a safety switch-off function that is much faster than the older one, and provides a rather accurate result too.


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