One of the World's oldest amusement parks still boasts one of the most thrilling dare devil rides thanks to powerful motor control options provided by the Optidrive Plus 3GV.
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Designed in 1899, the Park of Atraccions of Tibidabo is located on the Tibidabo mountain that is part of the Collserola range of hills in Barcelona city. One of the key atractions at the park is Atalaya, an imposing 50 metre high metal structure that takes visitors up to a height of 551 metres above sea level. Today, it´s still a truly unique ride that hasn´t lost its ability to offer an unforgettable experience. |
Throughout spring and summer about 7000 people visit the park every day and very few leave the park without having a ride on the Atalaya.
The swinging arm on the Atalya is required to reach maximum speed and then rapidly come to a stop when the passenger compartment at the end of the arm reaches maximium height. Over the past few years the Atalaya had been using a soft starter system system to help control this action, however this set up caused a swaying movement that made passengers feel very unsafe at such a high altitude.
There were also problems in windy conditions. The inefficiency of the soft starter system at low speeds (the transition from 50Hz to zero or vice versa) meant that the the Atalaya swinging arm was accelerated or braked until the motor reached the nominal speed where it could deliver full torque. Again this caused discomfort for the passengers on the ride.
This application for Optidrive Plus 3GV was undertaken by Rasesa Automatismos, Invertek Drives official distributor in Catalonia. Based in Sabadell,Barcelona, this company is part of a network of distributors developed by Invertek Drives (Spain).
Rasesa Automatismos were able to demonstrate how they could eliminate the negative issues being experienced on this ride by using the advanced motor control strategy available with the Optidrive Plus 3GV. The abilty of the Optidrive Plus 3GV to deliver 200% of torque at 0.0Hz and was the key deciding factor.
The new system on the amusement park ride is based in a 22kW AC motor with a break controlled by a 400V, 22kw Optidrive Plus 3GV. The results has been truly amazing, ensuring that the Atalay will remain a trusted and busy visitor attarction at the park for many years to come.
The Atalaya ride now comes to a stop in a very controlled manner, with no swaying motion in the passenger compartment after the swinging arm has been brought to a halt. Windy conditions no longer have a negative effect on the ride performance and with no limits on the number of starts per hour that can be undertaken, as was the case with the soft starter system, the productivity of the ride has dramatically increased.
Mr. Ramoneda and Mr .Serracant of Rasesa Automatismos were delighted with the results, commenting:
"The motor control performance of the Optidrive in this application is excellent, providing such precise control of a fifty metre swinging arm. Once again Optidrive has delivered outstanding results in a very challenging application!"
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Technical Viewpoint
Kes Beech, Technical Manager at Invertek Drives, explores the technical issues raised in the Atalya amusement park ride application. |
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This is a great example of where an Optidrive Plus 3GV demonstrates a clear advantage over a soft start in terms of the ability to accurately and smoothly control a difficult load during starting and stopping.
The size of the Atalaya system means that considerable inertia is involved, which requires very close control of the motor. With a soft start, the only available control is to limit the current into the motor, so the rate of acceleration is not actually controlled directly. This means that often the settings require a compromise to allow the motor to generate sufficient torque and avoid stalling, which in this application will severely compromise the ride comfort for passenger.
The Optidrive Plus 3GV on the other hand directly controls both the frequency applied to the motor and the output torque, ensuring that the smoothest possible start is achieved. The acceleration time can be simply set in parameter P1-03 to achieve optimum comfort, whilst the drive then operates in 3GV sensor less vector speed control mode (P4-01=0) to ensure that the required torque is delivered to meet the acceleration requirements.
Effectively, the parameters required for torque and acceleration rate are independently controlled, meaning that there is no compromise with the Optidrive system.
As an added benefit, since the drive controls the motor speed directly from zero, the peak current into the drive during starting is dramatically reduced, to a maximum value of less than 1.5 times the motor rated current, providing an additional energy saving benefit.
The even clearer advantage of the Optidrive Plus 3GV though is during system stopping. In most cases where a soft start is used, the motor power will simply be removed and the motor holding brake applied, resulting in a sudden jolt to stop, and the rocking motion described in this application. Some soft starts offer DC injection braking or reverse phase braking, and both of these techniques place a lot of stress on mechanical components, due to their harsh nature.
The Optidrive Plus 3GV with a brake resistor connected provides smooth control of the motor during the stopping phase, ramping down the motor frequency to bring the system to a smooth standstill, even with the inertia involved in this application. The motor holding brake can then be applied at or close to zero speed, controlled by an output relay from the Optidrive, reducing the wear on the brake linings, the mechanical stresses on the system, and of course, increasing the ride comfort for the passengers.
In many ways, the control required here is very similar to an elevator, where a smooth ride is essential, and this can only be achieved using vector control. The Optidrive Plus 3GV sensor less vector control has proved time and time again that in this type of demanding application, it provides the ultimate motor control without the need for encoder feedback. Overall, if a system demands smooth starting and stopping behaviour, there is no contest, the Optidrive Plus 3GV wins against the soft start every time. |
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