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Choose the right equipment for automated EV testing

March 11, 2015

Testing the electric motors and the electronic control modules found in today's electric vehicles (EVs) and hybrid electric vehicles (HEVs) is in many ways more challenging than testing internal combustion engines and their control modules. For one thing, HEV electric motors spin faster than internal combustion engines. They also must change speed more rapidly than internal combustion engines, and because some are designed to also generate energy, the test system must also measure the electrical output as well as the mechanical output of the motor.

In order to provide repeatable conditions when testing an EV's motors and modules, you need a high-power DC source to simulate the battery. Not only must the power source simulate the battery, it must be capable of simulating the power transients that may occur in operation.

Component tests
In an EV or HEV, as well as in many new conventional vehicles, components such as coolant pumps, air-conditioning compressors, and power steering systems are electrically powered from a low-voltage DC bus. To test these components, you need a power source that simulates the power supplied by a vehicle’s DC/DC converters or low voltage battery. Because these DC/DC converters may supply up to several kW, you need a DC supply that can also supply that much power.

To test the DC/DC converters that provide the voltages used by these components, you need a high-voltage DC source to simulate the battery and an electronic load that can simulate the loads that these components present to the converters. Typically, these DC/DC converters accept input voltages of 400 VDC or more, so your test supply should be able to supply these high voltages.

Choosing the right equipment for automated test
While the primary consideration for choosing power supplies to run these tests is to ensure that they can supply the voltage and current needed to either simulate a battery or to run a high-power test, it’s also important that they have features that make it easy to automate tests. For example, Sorensen SG Series DC power supplies have digital interfaces that allow them to easily connect to an automatic test system. In addition, they have a unique sequencing feature that allows them to easily simulate the way a battery’s voltage changes as it is charged and discharged in operation. This capability frees up a test system’s controller to perform other tasks.

You’ll also want to make sure that the equipment you choose can be used in both research and development and in production. This will make it easier for R&D to share test data and test programs with manufacturing. For R&D use, instruments should be controllable from the front panel and fit easily on a workbench. When used in ATE systems on the factory floor, instruments should be rack-mountable and be programmable via one or more computer interfaces. AMETEK Programmable Power offers users all of these options.