Ultrasonik uyarıcı dizisi ve güç odaklayan sürücü devre gerçeklemesi
Ultrasonic actuator array and power focused driver circuit verificaion
Yazar: YAVUZ ERŞAT KABUKCU
Danışman: DOÇ. DR. MÜRVET KIRCI
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Elektronik ve Haberleşme Mühendisliği Ana Bilim Dalı / Elektronik Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2015
Konu: Elektrik ve Elektronik Mühendisliği = Electrical and Electronics Engineering

Özet:
Ultrasonik dönüştürücü, elektrik akımını ses dalgasına, ses dalgasını elektrik akımına dönüştüren elemana denir. Bu devre elemanı iki yönlü olarak çalışmaktadır. Bu çalışmada, ultrasonik uyarıcı tasarlanmak üzere, sadece sürücü devreden gelen elektrik akımını ses dalgasına çeviren ultrasonik dönüştürücüler kullanılacaktır.
Bu tez çalışmasında, ultrasonik dönüştürücüler kullanılarak istenilen frekansta elde edilen ultrasonik dalganın bir noktada odaklanarak basınç şiddetinin arttırılmasını sağlayan, ultrasonik uyarıcı sistem tasarımı ve gerçeklemesi anlatılmıştır. Ultrasonik uyarıcı devreler çok farklı alanlarda(uzaklık ölçümü, endüstriyel temizleme v.b.) çeşitli amaçlarla kullanılmaktadır. Bu çalışmada ise tasarlanacak devre ve uyarıcı dizi tasarımları ile tarım alanında böcek yönlendirme kovma uygulamalarında kullanılması düşünülmektedir. Bunun için öncelikle hangi frekansta çalışılacağına karar verilmiştir. Bu problem farklı frekanslarda farklı devrelerin tasarımını gerektirmiştir. Bundan dolayı çalışma frekansına uygun devre tasarımları bulunarak gerçeklemesi yapılmıştır. Devre tasarım çalışması yapılmadan önce, ultrasonik dönüştürücülerin etki alanı uzaklığı hesabı yapılmıştır. Bu hesaplamalardan sonra, tasarlanacak uyarıcıda kullanılacak ultrasonik dönüştürücü dizi modelleri karşılaştırılmasını yapmak amacıyla belirlenen dizi modelleri gerçeklenmeden önce MATLAB benzetim ortamında TAC uygulaması ile ultrasonik dönüştürücülerden yayılan dalga yapısı elde edilmiştir. Son aşama olarak, devre ve dönüştürücü dizileri gerçeklenerek ölçümleri yapılarak ve bu ölçüm sonuçları değerlendirilmiştir.
İlk olarak, çalışmada her bir frekans farklı basınç değerleri için hangi ultrasonik dönüştürücülerin kullanılacağı ve dönüştürücünün çalışma frekansı belirlenmiştir. Çalışmada kullanılacak dönüştürücü tipleri, 400st100, 400st160 ve 90-4050-60 seri numaralı ürünlerdir. Bu dönüştürücülerin merkez frekansı 40 KHz, 80 KHz 'dir. Sonrasında, bu çalışma frekansına uygun bu dönüştürücüleri sürebilecek sürücü devre belirlenmiştir. Bunun için üç adet farklı sürücü devre kullanılmıştır. Bu devreler aynı veya farklı frekanslarda farklı dönüştürücüleri sürmek ve elde edilecek değerlerini kıyaslamak için bu şekilde seçilmiştir. Sürücü devrelerin gerçeklenmesine geçmeden önce, kullanılacak dönüştürücülerin hangi prensibe göre dalga ürettiğini ve bununla ilgili ultrasonik dönüştürücülerin parametreleri ve etki alanı uzaklığı hesapları yapılmıştır. Bu hesaplamalar ışığında, yapılacak ölçüm uzaklığı ve dönüştürücünün ilgili parametreleri hesaplanmıştır.
Bunun yanında, yapılan gerçek ölçümler ile karşılaştırmak amacıyla, ultrasonik dönüştürücülerin oluşturacağı dalga modelini gösteren ve matematiksel olarak yapacağımız hesaplarında doğrulanacağı ortam olarak MATLAB_TAC (Transducer
Array Calculation) uygulaması kullanılmıştır. Burada, benzetim ortamında hangi dönüştürücü kullanılacaksa onun parametreleri girilerek istenilen etki alanı uzaklığı ve oluşacak maksimum güç elde edilecektir. Bu işlem diğer dönüştürücüler ve dizi tipleri için tekrarlanarak gerçekte yapılan ölçümler ile karşılaştırılma olanak sağlamıştır.
Son aşamada ise, devreler ve dönüştürücü dizileri belirlenerek ölçümler yapılmıştır. Bu ölçümler, çalışma frekansına, dönüştürücünün cinsine, dönüştürücü dizilerine ve yapılan ölçümlerin uzaklıklarına göre karşılaştırılmıştır. Bu ölçümler sonucunda elde edilecek verilerden hangi düzeneğin daha verimli çalıştığı belirlenecektir. Bu çalışmada sadece devre ve dizi tasarımları yapılmış ve 40 KHz ve 80 KHzlik devre gerçeklemeleri yapılmıştır. Diğer frekanslardaki uygulamalar ve uygulamada hangi devrenin daha iyi sonuç vereceği başka bir çalışmaya bırakılmıştır.

Abstract:
The ultrasonic transducer is a device that is converting the sound waves into electrical current and also, sound waves into electrical impulses. This circuit element works in two ways. In this study, to design an ultrasonic actuator, which converts an electric current to only the sound waves from the ultrasonic transducer drive circuit will be used. In this study, to design an ultrasonic actuator, the ultrasonic transducer which converts an electric current that came from the drive circuit to only the sound waves will be used.
In thesis study, the ultrasonic actuator system design and verification were explained with using ultrasonic transducer to obtain the desired frequency of the ultrasonic wave in order to increase the pressure intensity at a point focusing. Ultrasonic actuate circuits were used different areas (distance measurement, industrial cleaning etc.) for various purposes. It was thought that this circuit and the actuator array were designed for using in redirecting and firing the insects in agriculture applications in this study. For this reason, it was primarily decided to which the working frequency is. These problems had lead to the design of different circuits working with different frequencies. Therefore, the realizations of the optimum circuits in operating these frequencies were made. Before the circuit design study was conducted, the influence field distance of the ultrasonic transducer had been calculated. After these calculations, the purpose of comparing to the ultrasonic transducer array models using for the ultrasonic actuator design before they were verified, the emitted waveform of the transducers were obtained from the TAC application of MATLAB simulation medium. Finally, the circuits and the transducer arrays were realized, besides this, their measurements were done and they were evaluated before last section. In last part, the consideration and the comment about this thesis study and the results was done.
Initially, 400st100, 400st160 and Apc90-4050-60 serial number ultrasonic transducers were determined for using in the study. The operating frequencies of these transducers were over 40 KHz of three and 80 KHz in order. Afterwards, the driver circuits were appointed to drive the convenient circuits. For this purpose, three different driving circuits were used.  Some of them operate in the same frequency and some of them operate in different frequency, by this way these different measurement values could be compared. Before the realization of the driver circuit, the working principle of the ultrasonic transducers which was emitted the wave and in relation to this the parameter of them and the calculation of the influence field distance were established. According to this calculation, the other parameters of the transducer and the measurement distance were assessed.
The main parameter of transducers used in calculation and measurement is the natural focused zone distance named by near field which is depended on the working frequency and diameter of the transducer. This distance determines the boundary between the near field and the far field. If it is possible that measurement at this point, the results could be more satisfied. However, the near field distance of some transducers is too short to measure, so the measurements were made at the point in the far field.
Moreover, it is used the array types to generate more high power at a point than getting from single one. The 400st100 and 400st160 transducers were combined in six different array models and the two driven circuits. Firstly, it is worked by itself. Secondly, two separate circuits drove the transducers and they had a distance, 3λ/2, between them. Thirdly, two transducers were driven by one circuit with connecting in series. Also, the distance between them is still 3λ/2. Fourthly, they were driven by three separate circuits and also, they were stood in line with 3λ/2 margin. In last two array models are square and rectangle of (3x2). The square model was existed with a pair of transducers connected in series to one driver circuit. They were positioned in 3λ/2 distance. The transducers formed of rectangle also positioned in 3λ/2 distance. In this array, each pairs of transducer were connected each other in series and a pair of them were driven by a circuit. The Apc90-4050-60-70 ultrasonic transducers were just measured by themselves without using in any array combination because of the lack of the number of driver circuit. 
Additionally, MATLAB_TAC (Transducer Array Calculation) application which is shown the waveform of the ultrasonic transducers and verified the mathematical calculation was used in order to compare the real measurements. It is tried that the existent circular transducers are simulated in the TAC application although it calculates the pattern of the rectangular ones. The useful approximation was applied to cope up with this contradiction. After that, three different transducers' parameters and array types are entered the application in order, and get the near field distance and the maximum power was obtained at the required point from entering the parameters of which transducer is used in the application. 
The last stage, the circuits and the ultrasonic transducer arrays were determined and the results of the transducer measurements were collected. The measurements were made with the AviSoft-SASLab listening media programme and a special microphone. The measurements were collected in 3 cm and 5 cm for 400st100 and 400st160 transducers as the near field distance of them are too short. Apc 90-4050-60 transducers were also measured in some different distances which included the near field distances. These measurements were compared each other according to the operating frequency, the type of the transducers, the array model and the measurement distance.
 When the measurement results were compared, the first circuit were better stability at frequency response than the second circuits. Nevertheless, the higher power was obtained from the second circuit than first one. Mostly, the measurement from 3 cm had higher volume than 5 cm measurements, because of the proximity to the transducers, yet, some array combinations, the wave from different transducers were absorbed each other, so the nearest result was lower than the farthest. Lastly, the 400st160 gave higher power when it was driven by first circuits. Additionally, when the second driver circuits worked with 400st100, it had given higher power at any array model.
After the measurement of 400st100 and 400st160, APC 90-4050-60 transducers' measurements were made at different distance. APC 90-4050's working frequency is 40 kHz and APC 90-4050's working frequency is 80 kHz. Both of them were driven by the same circuit which is emitted the wave in 80 kHz. In spite of the measurement of 400st100 and 400st160 in array, APC 90-4050-60 transducers were measured as a single in different distance. Firstly, APC 90-4050 was measured from near field distance. After that, the microphone was progressively put in farther from the transducer. These distances for APC 90-4050 were 5.9 cm, near field distance, 9 cm, 12 cm, 14 cm, 20 cm and 25 cm. These distances for APC 90-4060 were 9 cm, near field distance, 12 cm, 14 cm, 20 cm, 25 cm, 35 cm and 50 cm. The outcome of the near field measurements were more higher than the other distances' outcomes, on the other hand, the distance between the microphone and transducer was farther, the outcomes of the measurements were decreased in amplitude. Besides, the comparison of the transducer power by them, APC 90-4060 had a better performance than APC 90-4050 in the same distance measurement. This is because, APC 90-4060 has the matching frequency with driver circuits and it has more power than APC 90-4050. Therefore, the result of the measurements of APC 90-4050-60 with third circuit was supported to our thought about the near field distance of ultrasonic transducers and the obtained focused power.
In this study, not only the circuit and the arrays are designed but also the circuits of 40 KHz and 80 KHz are executed. The other frequency implementations and the decision which circuits give better values than the others are left to the future studies.