Industrial Alternator Tester
|Teaming||Specifications, Schedules, Budgets, Sharing a Client's "Vision"|
|Technical||Electronics, Industrial Controls & the Physics of rotating machines|
|Software||Embedded C, Microchip© PIC16C74, PIC16C77 firmware, Real-Time systems|
|Hardware||System & circuit design, layout, component selection, prototyping, testing|
Rebuilding automotive alternators is a competative, demanding business. Pressured by high volumes and low margins, Rebuilders need accurate, reliable equipment that withstands harsh conditions and provides fast results.
The instrument in the photo can thoroughly test an alternator to the latest SAE (Society of Automotive Engineers) specifications in about 60 seconds, depending on the (stored, selectable) setup.
The Operator mounts the device-under-test (DUT), selects a pre-configured sequence and touches "RUN". The Supervisor-configured tests are performed automatically and the results are displayed in graphic form, with a "PASS\FAIL" label for attachment to the DUT.
The challenge is rapid change in a competative market. New Automotive designs are closely guarded, with electronics playing an increasing role. New vehicles can have a dozen embedded microprocessors and numerous motors & actuators for emissions control, engine management, suspension, braking, entertainment and climate control. They all use power.
The old, 12-volt generation systems can't meet the demand (in watts of generation per cubic-inch of under-hood space), so new designs are appearing at 24 and 36 volts, with talk of 42 volt systems on the horizon. Each new alternator is different: many embed the voltage regulation within the alternator but some use external regulation, which may be a discrete unit or located in a central control unit with other duties. And the trend to automotive "bus" architectures (CAN bus, etc) is adding diversity.
Test instrumentation in this market must be agile to meet the changing demands.
The design goal was a lab-quality instrument, at an industrial-strength price, that can test foreign & domestic alternators to the latest industry specifications, as quickly as possible.
This system uses an industrial PC running a custom, object-oriented application under Windows© NT. The PC is equipped with a keyboard & touch-screen, and motion is provided by a single-phase 220VAC motor with a variable-frequency drive (VFD). The Graphical Man-Machine Interface (GUI, MMI) provides access to stored "menus" that draw from a massive, proprietary database of alternator performance information.
The heart of the system is a custom circuit assembly powered by a MicroChip© PIC microcontroller. The board includes a 12-bit measurement system, D/A capability for the VFD and switching circuits to control the AC & DC hardware. The PC issues commands to the PIC, which configures the hardware accordingly, performs the requisite measurements and reports the results to the PC.
As is sometimes the case, our company's involvement with this project began at the eleventh hour. The system had been designed. The original prototype seemed to function correctly (after much "tweaking") but the first production units had multiple, severe problems. Production was halted. And the man who designed the firmware & system circuitry was leaving the State. No kidding.
We met the challenge. Our background in industrial instrumentation and Embedded Systems development, combined with our active participation in the local branch of the SAE provided the necessary resources.
We reviewed the design and found that, while the MMI component was well-accomplished, the hardware & embedded intelligence needed attention in several respects. We were able in short order to accomplish surgically-precise hardware revisions and a major firmware overhaul. (Many issues can be resolved in software, which is often much less expensive than replacing the hardware...)
We also established a documentation protocol, insituted a written System Specification and negotiated a simple but effective version-control system for all product software.
Our Client is now proud to offer a fully functional product.
Truly a "state of the art" instrument!
While you're surfing, be sure to visit Northwest Regulator Supply Co's website for an update on their broad line of instruments that test automotive starters and alternators.
©Copyright 1999-2001 Barrett & Assoc. Engineering, revised 01/05/27