Dedicated Ultrasonic Motor Drive Circuit Study

Ultrasonic Motor (USM), as a new type of micro-motor, is different from the conventional electromagnetic motor. In the introduction, USM's advantages compared with the conventional electromagnetic motor, main constructs and the prospect of application are introduced. Based on the demands of miniaturization, the background and the main tasks of this special driving circuit are introduced, too. Designing such a circuit, making a prototype and matching with USM are the main tasks of the author. So this paper is the conclusion of these work motioned above.First, after studied many conventional system schemes of driving circuits adopted in this domain and based on actual requirements, a system scheme for this special circuit is designed. In this scheme, frequency tracing unit is canceled, a position locating and error clearing unit is instead. DSP is adopted as the control unit which has many functions such as forming the driving signals, selecting motors and controlling motors start, processing the signal of the position locating and decoding other special signals. Combined software with hardware benefits the miniaturization and the stability of the system. So this design has a novel and unique feature.Secondly, a method combined simulating with practical test is introduced in detail. An engineering design and test for the push-pull inverter and pulse transformer is done. Some questions, especially how to suppress the surge of the circuit and how to protect the power MOSFETs are solved. In the same time, the relationship between the manufacture technology of transformer and leakage inductance is noticed. Many control functions and combination between hardware and software are finished by DSP. And corresponding C program is offered. Adopted a unique digital encoding method, a construct using for position locating is designed. The result of test shows that this design can clear cumulate error and satisfy the special demands. At last an engineering PCB is finished and two prototypes are formed. Matched with USM, these two prototypes are validated by experiments. The result shows that main designing figures are achieved.At last, the work done in the first step is summarized and some requirements, especially the minds about engineering application and system integration are put forward, too.