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Tham khảo tài liệu 'mechatronic systems, simulation, modeling and control 2012 part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Electromechanical Analysis of a Ring-type Piezoelectric Transformer 13 c 3rd vibration mode a 1st vibration mode b 2nd vibration mode Fig. 5. Vibration modes of piezoelectric transformer. Fig. 6. Input and output impedance 4.2 Voltage Step-up Ratio Output Power and Efficiency The experimental setup for the measurement of the voltage step-up ratio and output power of the PT is illustrated in Fig.9. A function generator NF Corporation WF1943 and a high frequency amplifier NF Corporation HSA4011 were used for driving power supply. The variation in electric characteristics with load resistance and driving frequency were measured with a multi-meter Agilent 34401A . The voltage step-up ratios as a function of frequency at different load resistances were measured and compared with theoretical analysis as shown in Fig.10. It shows that the experimental results are in a good agreement with the theoretical results so the proposed electromechanical model for the PT was verified. Fig. 7. Experimental setup 14 Mechatronic Systems Simulation Modelling and Control Piezoelectric coefficient d31 -125X10-12 C N Coupling factor kp 0.59 Mechanical quality factor Qm 500 Dielectric constant 33 0 1694 Density p 7600 g cm3 Young s modulus Y11E 8X1010 N m2 Table 1. Properties of piezoelectric material. Input piezoelectric capacitance Ci 1.5nF Output piezoelectric capacitance Co 671.5pF Input turn ratio Ai 0.1198 Output turn ratio Ao 0.07545 Effective mass mi 4.773X10-4 kg Effective damping di 1.868 N-s m Effective stiffness k1 1.569X108 N m Table 2. Parameters of the equivalent circuit Fig. 8. Calculated input impedance Electromechanical Analysis of a Ring-type Piezoelectric Transformer 15 Fig. 9. Measured input impedance Vo Vi Fig. 10. Voltage step-up .
