超声电机LLCC谐振电路研究

Study on Driving Circuit of Ultrasonic Motor With LLCC Resonant Technique

超声电机需要幅值较高的驱动电压,因此其驱动电路需要变压器升压。超声电机为非线性容性负载,需要进行阻抗匹配,并保持电压和相移恒定。采用推挽电路作为驱动器拓扑,分析了该驱动电路在不同性质负载情况下工作过程,结果表明驱动器在感性负载时的开关管损耗较容性负载时小,感性负载可提高驱动器效率和可靠性。给出LLCC谐振网络及其参数计算方法,通过理论分析和仿真证明了电机谐振电压和相移与驱动条件可解耦,且该LLCC谐振网络可使驱动电路的负载性质由容性转变为感性。用TRUM-60型超声电机进行实验,结果证明了该方法的有效性。

High driving voltage is required for ultrasonic motors, so the driving circuit needs a transformer to boost voltage. Since the ultrasonic motor （USM） is a nonlinear capacitive load, a matching circuit is needed to keep the output voltage and the phase shift constant. Based on the switching circuit with push-pull topology, it was analyzed that the switching loss under inductive load is less than that under capacitive load, which will increase its efficiency and reliability. A novel LLCC resonant network was proposed and its parameters were given. Theoretical analysis and simulation were presented, which demonstrated that the output voltage and the phase shift of the resonant network can be decoupled from driving conditions, and the load characteristics can be changed from capacitive to inductive. This novel driver has been applied to the TRUM-60 type ultrasonic motor, and the experimental results have verified the effectiveness of the proposed circuit.