This document proposes and validates an equivalent circuit model for a wireless power transfer system capable of transferring 220W of power over a 30cm air gap with 95% efficiency. The model represents the transmitter and receiver coils as inductors with low mutual coupling. Analytical expressions for the model are derived and validated using finite element analysis and experimental results. Loss analysis is also performed to investigate skin effect and proximity effect losses at high operating frequencies. A new coil spatial design is proposed to reduce such losses compared to conventional coil designs.
This study analyzed optimization of wireless power transfer using a half-bridge flyback converter. The researchers designed a protection circuit to maintain the resonant frequency as the load changed. Experiments showed wireless power transfer of over 3.4W and 61% efficiency to a variable LED load. Adding the protection circuit produced more stable output than without it by preventing changes in resonant frequency from load variations.
This document presents a study of loosely coupled coils for wireless power transfer. It begins by introducing the concept of using magnetically coupled coils for nonradiative wireless power transfer. It then presents a conceptual wireless power transfer system and a tuning method for transferring a predetermined amount of power at maximum efficiency. Equations are derived for calculating inductance, resistance, coupling coefficient, power transfer capability, and efficiency. The performance of the proposed system is evaluated and verified using known experimental results and circuit simulations. Key aspects of the study include developing explicit design equations for tuning the wireless power transfer system to achieve a target power level with optimal efficiency.
This document summarizes a research paper on the design of a low-power rectenna for wireless power transfer. It discusses the analytical modeling and optimization of individual rectenna elements, including the microstrip patch antenna, Schottky diode model, and output filter. Simulation and experimental results show that directly matching the rectifier impedance to the antenna improves efficiency over traditional designs using a coupling capacitor. Optimizing the output filter also reduces harmonic power dissipation, further improving efficiency. The rectenna efficiency is found to increase with higher input power levels as discussed.
This document proposes a system for wireless power transfer to electric vehicles using magnetic resonant couplings. It presents experimental results on helical antennas that could be installed on electric vehicles. The experiments show that:
1) Resonant frequencies of the transmitting and receiving antennas change depending on the air gap between them, but maximum efficiency remains high even for large air gaps.
2) Efficiency remains around 95-97% for air gaps up to 200mm and remains high even when coupling coefficients are weak at large air gaps.
3) Efficiency remains constant, around 95-96%, for varying power levels from -15dBm to 100W, showing that efficiency does not depend on power as predicted by equivalent circuit models.
The document describes a method for detecting different operating modes in a wireless power transfer system. The system can detect three modes: 1) no-load mode when no receiver is present, 2) safe mode during normal power transmission, and 3) fault mode if a conductive or magnetic object interferes. The method analyzes the transmitting coil voltage and supply current without needing communication between the transmitter and receiver. It aims to reduce power consumption during no-load operation and protect the system from faults.
This summary provides the key points about a study on frequency-tracking wireless power transfer systems using resonant coupling:
1) Detuning is a barrier to resonant coupling wireless power transfer, as changes in coil inductances can reduce transmission efficiency.
2) A new frequency tracking control method is proposed where the transmitting power source frequency tracks the natural frequency of the launching resonant circuit automatically to avoid detuning and improve efficiency.
3) An experimental 1 MHz wireless power transfer prototype was built using this frequency tracking method, and results showed it performed well in maintaining high transmission efficiency despite changes in coil inductances.
This document describes a wireless power transfer system using thin film resonant cells for powering implanted and worn medical devices. The system uses resonant magnetic coupling between a transmitter coil placed around the waist and receiver coils near the implanted/worn devices. The thin film cells are made of flexible copper tape and polymer layers to be lightweight and conform to the body. Experimental results show the system can efficiently transfer power over longer ranges than existing magnetic coupling methods, with 40.2% efficiency achieved at a 20cm distance.
This document discusses millimeter-wave wireless power transfer technology for space applications. It proposes a new compact design using a 20x20 slot antenna array integrated on a gold-silicon-silicon dioxide substrate that is capable of realizing over 72% conversion efficiency and power densities over 1.2W/cm^2. The slot antennas are coupled to a differential RF-to-DC conversion circuit consisting of a rectifier, filter, and storage capacitor. This technology offers higher efficiency and power density than solar arrays and could enable rapid wireless power transfer for lunar and space systems without a traditional power grid.
This document describes the design and testing of a high-power, high-efficiency wireless power transfer system using loosely coupled planar inductive coupling. The system uses a class-E inverter to transmit power via inductive coupling coils to charge devices without a complex external control system. The designed system achieved 295W of power delivery at 75.7% efficiency with forced air cooling and 69W at 74.2% efficiency with natural convection cooling, representing the highest power and efficiency reported for a loosely coupled planar wireless power transfer system.
This document describes a new prototype of a wireless micro-robot system for use in endoscopes. The micro-robot uses earthworm-like locomotion powered by three linear actuators and wireless power transfer. It has been tested moving autonomously through rubber canal models and pig intestines. The wireless power transfer system provides up to 480mW of power to the receiving coil in the micro-robot. Experimental results showed the micro-robot could reliably move forward and backward in the canals and intestines.
Wireless power transfer using weakly coupled magnetostatic resonators can increase power transfer and efficiency compared to magnetic induction alone. By adding capacitors in series with inductors in both the power sender and receiver to create resonant circuits, the power transfer increases by the sum of the quality factors of the two circuits times the sender's quality factor. The efficiency increases by half the product of the quality factors. However, the overall efficiency remains below 50% for all weakly coupled resonant systems. Resonators with a quality factor of 1,000 could transfer power over a distance 9 times the radius of the devices with 10% efficiency.
This document proposes and validates an equivalent circuit model for a wireless power transfer system capable of transferring 220W of power over a 30cm air gap with 95% efficiency. The model represents the transmitter and receiver coils as inductors with low mutual coupling. Analytical expressions for the model are derived and validated using finite element analysis and experimental results. Loss analysis is also performed to investigate skin effect and proximity effect losses at high operating frequencies. A new coil spatial design is proposed to reduce such losses compared to conventional coil designs.
This study analyzed optimization of wireless power transfer using a half-bridge flyback converter. The researchers designed a protection circuit to maintain the resonant frequency as the load changed. Experiments showed wireless power transfer of over 3.4W and 61% efficiency to a variable LED load. Adding the protection circuit produced more stable output than without it by preventing changes in resonant frequency from load variations.
This document presents a study of loosely coupled coils for wireless power transfer. It begins by introducing the concept of using magnetically coupled coils for nonradiative wireless power transfer. It then presents a conceptual wireless power transfer system and a tuning method for transferring a predetermined amount of power at maximum efficiency. Equations are derived for calculating inductance, resistance, coupling coefficient, power transfer capability, and efficiency. The performance of the proposed system is evaluated and verified using known experimental results and circuit simulations. Key aspects of the study include developing explicit design equations for tuning the wireless power transfer system to achieve a target power level with optimal efficiency.
This document summarizes a research paper on the design of a low-power rectenna for wireless power transfer. It discusses the analytical modeling and optimization of individual rectenna elements, including the microstrip patch antenna, Schottky diode model, and output filter. Simulation and experimental results show that directly matching the rectifier impedance to the antenna improves efficiency over traditional designs using a coupling capacitor. Optimizing the output filter also reduces harmonic power dissipation, further improving efficiency. The rectenna efficiency is found to increase with higher input power levels as discussed.
This document proposes a system for wireless power transfer to electric vehicles using magnetic resonant couplings. It presents experimental results on helical antennas that could be installed on electric vehicles. The experiments show that:
1) Resonant frequencies of the transmitting and receiving antennas change depending on the air gap between them, but maximum efficiency remains high even for large air gaps.
2) Efficiency remains around 95-97% for air gaps up to 200mm and remains high even when coupling coefficients are weak at large air gaps.
3) Efficiency remains constant, around 95-96%, for varying power levels from -15dBm to 100W, showing that efficiency does not depend on power as predicted by equivalent circuit models.
The document describes a method for detecting different operating modes in a wireless power transfer system. The system can detect three modes: 1) no-load mode when no receiver is present, 2) safe mode during normal power transmission, and 3) fault mode if a conductive or magnetic object interferes. The method analyzes the transmitting coil voltage and supply current without needing communication between the transmitter and receiver. It aims to reduce power consumption during no-load operation and protect the system from faults.
This summary provides the key points about a study on frequency-tracking wireless power transfer systems using resonant coupling:
1) Detuning is a barrier to resonant coupling wireless power transfer, as changes in coil inductances can reduce transmission efficiency.
2) A new frequency tracking control method is proposed where the transmitting power source frequency tracks the natural frequency of the launching resonant circuit automatically to avoid detuning and improve efficiency.
3) An experimental 1 MHz wireless power transfer prototype was built using this frequency tracking method, and results showed it performed well in maintaining high transmission efficiency despite changes in coil inductances.
This document describes a wireless power transfer system using thin film resonant cells for powering implanted and worn medical devices. The system uses resonant magnetic coupling between a transmitter coil placed around the waist and receiver coils near the implanted/worn devices. The thin film cells are made of flexible copper tape and polymer layers to be lightweight and conform to the body. Experimental results show the system can efficiently transfer power over longer ranges than existing magnetic coupling methods, with 40.2% efficiency achieved at a 20cm distance.
This document discusses millimeter-wave wireless power transfer technology for space applications. It proposes a new compact design using a 20x20 slot antenna array integrated on a gold-silicon-silicon dioxide substrate that is capable of realizing over 72% conversion efficiency and power densities over 1.2W/cm^2. The slot antennas are coupled to a differential RF-to-DC conversion circuit consisting of a rectifier, filter, and storage capacitor. This technology offers higher efficiency and power density than solar arrays and could enable rapid wireless power transfer for lunar and space systems without a traditional power grid.
This document describes the design and testing of a high-power, high-efficiency wireless power transfer system using loosely coupled planar inductive coupling. The system uses a class-E inverter to transmit power via inductive coupling coils to charge devices without a complex external control system. The designed system achieved 295W of power delivery at 75.7% efficiency with forced air cooling and 69W at 74.2% efficiency with natural convection cooling, representing the highest power and efficiency reported for a loosely coupled planar wireless power transfer system.
This document describes a new prototype of a wireless micro-robot system for use in endoscopes. The micro-robot uses earthworm-like locomotion powered by three linear actuators and wireless power transfer. It has been tested moving autonomously through rubber canal models and pig intestines. The wireless power transfer system provides up to 480mW of power to the receiving coil in the micro-robot. Experimental results showed the micro-robot could reliably move forward and backward in the canals and intestines.
Wireless power transfer using weakly coupled magnetostatic resonators can increase power transfer and efficiency compared to magnetic induction alone. By adding capacitors in series with inductors in both the power sender and receiver to create resonant circuits, the power transfer increases by the sum of the quality factors of the two circuits times the sender's quality factor. The efficiency increases by half the product of the quality factors. However, the overall efficiency remains below 50% for all weakly coupled resonant systems. Resonators with a quality factor of 1,000 could transfer power over a distance 9 times the radius of the devices with 10% efficiency.
1. FUNDAMENTALS OF CONTROL SYSTEMS
Kontrol Sistemlerine Giriş ve Tanımlar :
Sistem : Girişlerdeki değerlere göre gerçek çıkış değerleri üreten bütünlüğe sistem adı
verilir.
Not: Girdi ve çıktılar genellikle zamanın bir fonksiyonudur.
2. Girdi ve Çıktı : Bir kontrol ( denetim ) sistemi verilen bir girdi veya uyarıcı için çıktı
veya cevap sağlar.
Girdi, istenen cevabı gösterir.
Çıktı, gerçek cevabı gösterir.
Sistemlerin Sınıflandırılması
Deterministic ve deterministic olmayan : bir sistemdeki çıkışlar sadece girdilerle
tanımlanıyorsa o sistem deterministic ( belirleyici ) olarak adlandırılır.
Statik ve dinamik : t zamanındaki y(t) çıkış değerleri sadece aynı t zamanındaki x(t)
değerlerine bağlıysa sistem statiktir
Causal ve causal olmayan : t = t0 da y(t) değerleri sadece t<= t0 zamanında x(t) nin
değerlerine bağlıysa sistem causaldır. (not: statik sistemler causaldır)
Sürekli – zaman ve Kesikli – zaman sistemler : bir sistemin girdi ve çıktılarının her
ikisi de sürekli- zaman ölçeğinde tanımlanırsa sistem sürekli-zaman sistemidir.
3. Zamanla değişen ve zamanla değişmeyen sistemler : bir sistemin girdi-çıktı ilişkisi
zaman içerisindeki değişmiyorsa bu sistem zamanla değişmeyen bir sistemdir.
Doğrusal ve doğrusal olmayan sistemler : bir sistemin girdi-çıktı ilişkisi doğrusal ise
sistem doğrusaldır.
Örnek : Zeminden 4. kata çıkacak olan bir asansörün düğmesine basıldığında sabit bir
hızla ve zemin seviye hata ölçümüyle 4. kata çıkar.
4. Asansörün zeminden 4. kata kadar olan yükselmesindeki değişim (Transient
response) ( geçici ) geçiş cevabı’dır.İstenen duruma gelmesi kararlı hal
cevabı’dır.İstenen durum ile kararlı hal arasındaki hata ise kararlı hal hatası olarak
adlandırılır.
Açık Çevrim Sistemler:
5. Girdi, referans olarak da adlandırılır.Girdi dönüştürücü – girdi değerini gerilim
veya akım gibi fiziksel büyüklüklere dönüştürür ( Girdi dönüştürücüden hemen sonra
denetleyici gelir.) diğer gürültüler sisteme dışarıdan istem dışı gelir.Çıktıya da
denetlenen ( kontrol edilmiş ) değişken denir.
. Uygulaması basittir (üstünlüğü)
Örnek : Fırın veya klimalı sistemde çıkış değişkeni sıcaklıktır.Isıtma sistemindeki
denetleyici yakıt ve elektrik valflerini içerir.
6. Açık çevrim sistemler:
Mekanik sistemlerde kütle, yay,piston hareketleridir.
Kuvvet büyüdükçe yer değiştirme de büyür.
Kapalı çevrim ( Geri beslemeli denetim ) sistemler:
Açık çevrim sistemlerin dezavantajı gürültüleri önleyebilecek kapalı çevrimin
olmayışıdır.
7. Çıkış dönüştürücü veya sensör, çıkış cevabını ölçer ve denetleyicinin
kullanabileceği duruma getirir. Mesela denetleyici elektrik sinyallerini kullanırsa
sıcaklık kontrol sisteminin valflerini komuta eder. Konum girdiği potansiyometre (
değişkenli direnç ) tarafından gerilime dönüştürülür.
Sayısal denetleyiciler
A/D-D/A çeviriciler gereklidir
Özet olarak ;
Sensor
Digital
Controller
Input Output
A/D D/A Process
8. Sistemler önce ölçülür ve düzeltilirse bu sistemler kapalı çevrim veya geri besleme
denetimli sistemler olarak adlandırılırlar. Sistemler ölçülemez ve düzeltilemez ise açık
çevrim sistemler olarak adlandırılır.
Kontrol sistemlerinin amacı referans girdiyi izlemek (takip etmek )
Gürültüleri uzaklaştırmak
Algılayıcının transfer fonksiyonu 1’e yakınsa algılayıcı dinamikleri ihmal edilebilir
Girdi daima sıfırsa, özel durumdur ve sistem regulator olarak adlandırılır
Analiz ve Tasarımların amacı :
Genellikle girişe benzeyen kararlı hal (durum) cevabına ulaşmadan önce geçiş
cevabına maruz kalan kontrol sistemleri dinamiktir. Burada geçiş cevabı, kararlı hal
cevabı ve kararlılık üç ana kısımda incelenecektir.
Geçiş Cevabı : Önemlidir.
9. Asansör olayında yavaş geçiş cevabı yolcuyu sabırsızlandırır. Aşırı hızlı cevap
konfor sağlamaz ve kalıcı fiziksel hatalara neden olur.
Kararlı Hal Cevabı : Asansör 4. kata yakın yerde durabilir.
Kararlılık : Geçiş cevabı ve kararlı hal hatası sistemin kararsızlığında ortaya atılır.
Kararlılığı açıklayabilmek için ;
Toplam Cevap (Tepkime) = Doğal Cevap (Tepkime) + Zorlanmış Cevap (Doğal
tepkime çok büyüdüğünde) denkleminden faydalanmak gerekir.
Doğal tepkime, enerjinin toplanması veya dağılmasını tanımlar, tepkime girişe
bağlı değil, sisteme bağlıdır. Doğal tepkime en sonunda sıfıra yaklaşıyorsa (yani
zorlanmış tepkimeyi terk etmeli) veya osilasyona uğruyorsa denetleme sistemi
kullanışlıdır.
10. Doğal tepkime, zorlanmış tepkimeden çok daha büyükse sistem bir daha
denetlenemez.Bu duruma kararsızlık denir. Asansör ya zemin ile yada tavan ile yek
vücut olur.
Kontrol sistemleri kararlı olacak şekilde tasarlanmalıdır. Yani doğal tepkimeleri
sıfıra düşmeli (zaman sonsuza giderken) veya osilasyona uğramalıdır.
Bir Kontrol Sistemi Tasarımı İçin :
Araç ve gereçlerden fiziksel sistem ve özelliklerini tanımlamak
Fonksiyonel blok şeklini çiz
Fiziksel sistemi şematik olarak göster
Matematiksel modeli elde etmek için şemayı kullan (Blok yapı)
Blok diyagramına indirge
Kararlılık, geçici tepkime ve kararlı hal performansını içeren analiz ve tasarımları
yap
12. G(s) = noktası için s = 0 ve s = -1 noktalarına karşılık gelir. Ters görüntüleme
yapılamaz ve s = 0, s = -1 noktaları dışında denklem analitik bir fonksiyondur.
G(s) = s + 2 fonksiyonu sonlu s – düzleminin her noktasında analitiktir.
G(s) fonksiyonun kendisi ve tüm türevleri varsa bu fonksiyona analitik fonksiyon
adı verilir.
BİR FONKSİYONUN TEKİL NOKTALARI VE KUTUPLARI
(SİNGULAR POİNTS) (POLES)
Kutup en yaygın tekil noktadır.
G(s) fonksiyonunu ele alalım ;
)]()[( 1
1
lim sGss r
SS
Değeri sonlu ve sıfırdan farklı bir değer alıyorsa G(s), s=si’de r’inci dereceden bir
kutbu vardır.
13. MATEMATİKSEL TEMELLER
Geleneksel (Klasik) kontroldeki incelemeler için ;
Karmaşık değişkenler kuramı
Diferansiyel ve fark denklemleri
Laplace dönüşümü
Modern kontroldeki incelemeler için ;
Matris Kuramı
Kümeler Kuramı
14. Doğrusal cebir ve dönüşümler
Varyasyon hesabı
Karmaşık Değişkenler Kavramı:
Bir karmaşık s değişkeni s (gerçek) + jw (sanal) ‘dir. S düzleminin grafiksel
gösterimi ise ;
15. Eğer herhangi bir s değerine bir veya daha çok G(s) değeri karşı geliyorsa G(s), s
karmaşık değişkenin bir fonksiyonudur ve ;
G(s) = Re G(s) + jImG(s) ile gösterilir.
Sayısal kontrolün analog kontrole göre üstünlükleri
16. - Düşük enerji işaretine sahip hassas kontrol elemanları vardır
- Sayısal işaretler gürültülerden arındırılabilir ve yüksek oranda doğruluğa sahiptir
Zayıf noktaları
- Hibrit sistemlerin analizinde tasarım biraz daha zor
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