AUTHOR: Mr. Janagan Kanesamoorthy
Senior Application Engineer

The LV 123 standard can be applied on the inverter as standalone, e-motor or the complete drivetrain. The test standard is separated in two parts. The goal of the first tests is to check the system performance at the entire operating high voltage range and temperature range at the continuously operating capability range. The high voltage starts from 0 and the range is up to 1000V (based on customer requirements) and the test setup must comply with an ambient temperature range of -40 °C to 85 °C and coolant temperature range from -25 °C to 85 °C.

GETEC is using a Vehicle Energy System (VES) either in single mode or for higher requirements to the current it is used in parallel mode. The capabilities are listed in table 1.

Tab. 1 | GETEC VES capabilities





The test case for the upper limited operating capabilities for a given HV Voltage range is shown exemplary in figure 7. The purpose of this test is to check the inverter performance at the entire voltage range and temperature range at the upper limited HV voltage operating range.

Fig. 7 | HVDC Voltage upper limit operating capability

The cycle is repeated 3 times and the inverter must adapt its capabilities according to the HVDC set-point. It is obvious that the inverter limits its capability if the HV voltage exceeds the upper limit and recovers after the HV voltage falls below the limit value. The complete cycle is running automatically after programming the test bench control software according to the LV123 specification. The cooling circuit target temperature was set in this test case to -22 °C inverter inlet temperature.

Another test is performed to prove that the HVDC voltage is measured by two independent measurement paths and to verify them against each other. The inverter operates at its maximum capabilities for 6 different HVDC voltages up to maximum speed. Figure 8 gives an overview of the test cycle with the maximum torque and speed for generating and motor mode of the inverter.

Fig. 8 | HVDC Voltage plausibility check in motor and generator mode up to maximum speed and 6 different HVDC levels

The test bench automation skips the set point if the limit of the inverter is reached. This test cycle is performed with 65°C coolant temperature at the inverter inlet. During the test cycle the test bench automation monitors the critical parameters of the inverter and the e-motor to shut down the system safely in case of incidents and to prevent any damage of the test setup (refer to figure 9).

Fig. 9 | HVDC Voltage plausibility check with the inverter working at its limits

The advanced automation system of GETEC test benches allows to adapt quickly the already implemented test cycle to new devices under test. This enables to supply the results to the customers within shortest time. The equipment can perform the safety relevant tests for the new energy mobility.

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