AC drives: Vehicle wash systems gain uptime in extreme environments
An in-plant test bay for the new PDQ LaserWash M5 model at PDQ headquarters. Courtesy ABB
Avoiding vehicle corrosion is big business and ac drives are helping. According to the International Carwash Association (ICA), Americans spend more than $24 billion a year to repair automobile corrosion damage. The ICA recommends that consumers wash their cars at least once or twice a month to avoid environmental paint damage.
PDQ, said to be the world's largest manufacturer of touch-free vehicle wash systems, is named after its claimed attributes: performance, dependability, and quality. Founded in 1984 in De Pere, WI, PDQ was the first company to invent a robotic arch that closely follows the contours and shape of any vehicle, pioneering the way for touch-free, car-wash technology.
A vital part of PDQ's state-of-the-art LaserWash 4000 and LaserWash M5 vehicle washes is the motor drive that controls the washer components mounted on an overhead frame, which are called the bridge, trolley, and arch sections. When PDQ was looking for a reliable drive that would weather harsh environmental conditions, and perform well in its unattended carwashes, the company found what they were looking for in ABB's line of ac drives. They have been using these drives for over five years on the LaserWash 4000 and LaserWash M5 vehicle wash systems. PDQ is now field testing the next generation ABB drive on the LaserWash M5.
3 motors, 1 drive
The drive controls the speed of three different motors that operate the washer on the overhead gantry.
—First motor, rated at 1.3 hp, operates the bridge and is responsible for moving the apparatus from the front to the back of the vehicle.
—Second motor, rated at 0.5 hp, is used to move the trolley, which sprays a column of foam or water from left to right.
—Third motor, rated at 0.75 hp, moves the arch, which rotates on a 90-degree axis, to ensure that water is sprayed at the vehicle at all times throughout the cycle.
According to Ken Dollhopf, vice president of research and development at PDQ, all of the components need to work together precisely to provide an effective, efficient touch-free process. The drive also is responsible for ensuring that each motor runs at a specific time during the operation. Because the motor applications are unique, specific profiles are needed. Two sets of parameters are programmed into the drive: one for the bridge motor, and another for the trolley and arch.
To support PDQ's lean manufacturing process, ABB supplies drives pre-programmed and ready to be installed. Dollhopf says the pre-programming is important: "Our assemblers don't have to unpackage the drive or power it up; they can just plug it in. All the parameters are there. It's very simple and efficient."
The drive is located inside the white (cabinet) enclosure in the overhead gantry system of the LaserWash M5. Courtesy ABB
Auto-reset improves uptime
Automatic car washes are expected to run continuously, so it was imperative that PDQ use a drive that did not require manual resetting after a shutdown. Since many vehicle washes are located in remote locations, hours of productivity and profit can be lost if technicians are needed to reset drives. An auto-reset feature allows the drive to reset itself without manual override.
"If we ever have a problem, the last thing we want is for the drive not to reset automatically," says Mark Vickman, electrical detailer at PDQ.
Because car washes can be located in busy commercial places, drives must handle power fluctuations. With the washer weighing in at more than 2,000 lb and moving at approximately 70 cm/s, the drive needs adequate voltage to maintain motor operation. "In a commercial setting, however, our car wash may be right next to a big mall," says Dollhopf. "When they turn the lights on at night, the voltage may drop from 220 volts down to 188 volts in no time. We need a drive that is able to ride through large voltage fluctuations."
The drives also must perform well in extreme climates, since PDQ sells internationally. According to Dollhopf, in Europe, many PDQ car wash units are located outside in a parking lot, with exposure to direct sun on the electrical cabinet and temperatures as low as -20 °C
Dollhopf adds that, by using a 220-volt, single-phase input to the drive, PDQ can connect three-phase motors at any frequency level, removing the frequency level requirement in production. This also makes the vehicle washes easier to produce for global customers.
On previous car-wash models, the drive was located in the main power panel, usually located in the dry equipment room outside of the bay area. With the introduction of the new LaserWash M5, the drive is installed in a sealed cabinet directly on the bridge to reduce electromagnetic interference (EMI) emissions. If not properly controlled, EMI can disrupt nearby radio equipment and cause drive faults. European EMI regulations exceed those in the U.S. PDQ had to specify drives equipped with electromagnetic compatibility (EMC) filters to minimize interference.
Cooperative development and design of drives has created a strong relationship between PDQ and ABB. With the ACS350 now in field testing on the LaserWash M5, the changeover from current technology is planned for spring 2007.
—Edited by C.G. Masi , Control Engineering senior editor
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