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EMS testing with pulsed power supply device

01 Jul 2014  | Umesh Pralhad Patil, Ajit Basarur

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There was a recent issue that affected a few newly manufactured consumer vehicles. The units were tested okay at the time of rolling out from the assembly line but failed to start when they reached the dealer location. During the initial fault analysis, it was suspected to be related to the start-up of the engine management system (EMS). The EMS failed to start/boot up in the expected manner. Deeper analysis of EMS indicated that the flash memory was corrupted, and no specific reason could initially be identified. It was then concluded that because of mechanical vibrations during shipment, the vehicle's battery connection to the EMS was not always intact. Due to this fragile contact, EMS boot-up failed regularly or remained incomplete most of the time. During EMS boot-up, regular flash updates happened and hence the suspected condition was concluded to be the reason for flash memory corruption.

Figure 1: Pulsed power supply set up.

Simulation and cost restrictions
Simulating the above speculated condition in the lab environment requires an interruptible power supply source. Due to cost reasons, no test set ups were available in the lab to simulate such critical power failure conditions. Existing bench power supply units did not provide interruptible power supply options, and procuring new units that generate interruptible supply only for this method of EMS validation did not seem to be a viable option due to costs.

Figure 2: Smart hardware device internal block diagram.

Smart hardware device
To be able to test the EMS in such critical power failure conditions, a hardware device was developed. The proposed solution uses a smart hardware device between the test-bench power supply and EMS. This smart hardware device derives constant voltage from the existing test-bench power supply and generates interruptible power supply for the EMS as per the user requirements. Interruptible power supply provides configurable timed power pulses with resolution ranging from milli-seconds to seconds.

This smart hardware device can be retrofitted to any commercially available test-bench power supply modules. It supports dual trigger modes—namely "Internal" and "External (e.g. over PC)". Internal trigger mode supports the generation of continuous and timed pulses. In the external trigger mode, asynchronous and/or configurable pulses can be generated based on the external configuration.

Figure 3: Pulsed power supply GUI on host PC.

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