[关键词]

[摘要]

该文提出了一种 E类谐振逆变低频超声雾化喷头驱动电路,以基本的 E类谐振变换器为基础,结合超声喷头串联谐振时的等效电路,设计并制作了一款高功率、低成本的超声雾化驱动电路。介绍了电路结构、基本原理；分析了 E类谐振逆变电路最佳工作状态下的电路特性；给出了最佳状态时理论分析、波形说明及公式推导。在理论参数设计的基础上,结合 saber仿真软件对所求的理想参数验证,通过仿真波形图与实验波形图对比,结果表明,理论设计参数很好地符合仿真结果与实际结果。同时,详细分析了晶体管两端的并联电容的大小对电路的影响。

[Key word]

[Abstract]

Ultrasonic atomization atomizers are widely used in many fields with their excellent atomization properties.However, as a key part of ultrasonic atomization system, ultrasonic atomization nozzle driving powers are still costly,inefficient and unstable.In order to design an ultrasonic atomization driving circuit with high efficiency and low cost, aclass E resonant converter of high efficiency and low power dissipation was developed in this paper.The class E inverter isa well known resonant converter that can generate high frequency sinusoidal current and has high power conversionefficiency.Only one transistor with a control circuit was used in the main power circuit, which made the class E resonantconverter high efficiency and low cost solution for low frequency ultrasonic atomization atomizers.The nozzle adopted inthis paper was a novel micro index and low frequency ultrasonic nozzle whose parameters were as follows: input voltage36 V, resonant frequency 60 kHz and output power 15 W.A class E resonant inverter merged with the series resonanceequivalent circuit of nozzle at its resonance frequency was used to drive the low frequency ultrasonic atomizer at zerovoltage switching.It was analyzed that the basic circuit structure, working principles and circuit characteristics of class Eresonant inverter circuit under the optimal working condition.Additionally, a simplified model and merged model wererespectively used to calculate waveforms and ideal parameters of this ultrasonic nozzle.The ideal parameters werevalidated based on the theoretical calculations and simulations conducted in saber software.However, the voltagewaveform across the switch S was the key point to determine circuit performances.The shunt capacitor C,which was one of key parameters, was composed of the MOSFET output capacitance, the choke parasitic capacitance and the external shuntcapacitance.When the value of the shunt capacitor C was properly designed, the energy stored in the shunt capacitor C discharged entirely just before the switch S turned on and the switch turned on at zero voltage.In this case, with lessswitching lost, the maximum power could be achieved.When the value of shunt capacitance C was larger than optimal value, the voltage rate of rise and fall across the shunt capacitance C decreased during the switch off and the switch voltagewaveform did not reach zero prior to turn on switching.Therefore, the switching losses occurred instantly when the switchturned on and the MOSFET may be burned out.In contrast, when the value of capacitance C was smaller than ideal value, the energy stored in the shunt capacitor C was discharged completely in advance.Furthermore, the MOSFET body diodeturned on when the switch current was negative.Therefore, the turn on switching losses and the large conduction losses ofthe body diode occurred at the same time.In order to verify the design method, a driving circuit of a 15 W ultrasonicatomization nozzle was built.The experimental results showed that the class E resonant inverter could be succeeded inapplying to drive the low frequency nozzle and the circuit efficiency was 85% or more.The designed circuit wasinvestigated as a good solution to drive the low frequency ultrasonic atomization nozzle.Additionally, experimentalwaveforms were in a good agreement with simulation results.From the waveform charts, we can obtain methods of thequantitative parameter adjustment to reach optimum condition.

[中图分类号]

S224.3

[基金项目]

国家自然科学基金资助项目(51275214)；江苏省自然科学基类谐振 DC/AC逆变电路作为主功率电路 驱动电路主金资助项目(BK2011470)；江苏高校优势学科建设工程资助项目