The impedance matching of ultrasonic plastic welding machine is an important link in the ultrasonic welding process. In the process of ultrasonic processing, it is often encountered that the equipment power is insufficient. The reason is that the load of the ultrasonic power supply does not match the equivalent resistance of the transducer, resulting in the ineffective transmission of energy. At this time, impedance transformation is required. The equivalent resistance of the transducer is matched with the output impedance of the ultrasonic power through impedance transformation to ensure the transmission of energy. This is ultrasonic impedance matching. Impedance matching is also a function completed by the matching circuit. We usually The method of using output transformer or parallel capacitor.

The above are just some basic theoretical and practical knowledge of circuit matching in power ultrasound technology. The design and debugging of the actual matching circuit are more complicated. There are many reasons for this!

First of all, from the perspective of the ultrasonic generator circuit itself, using different formats of amplifying circuits, the design of the circuit operating point is different, the output impedance of the generator is different, and with the change of the working state of the circuit, the output impedance will also change. Therefore, It is difficult to guarantee an ideally matched ultrasound transducer for long periods of time.

Then in actual work, ultrasonic transducers have many characteristic frequencies, such as series resonant frequency, parallel resonant frequency and resonant frequency, anti-resonant frequency and small admittance frequency, large admittance frequency, etc., due to the boundary conditions of the sensor ( including electrical Unlike mechanical boundary conditions), it is difficult to guarantee that the sensor operates at a specific resonant frequency.

Third, at high power, matching becomes more complicated due to changes in load and sensor parameters (where frequency and impedance changes are important). In view of the above considerations, it can be said that electrical matching is a complex task in the development of high-power ultrasonic equipment.

In the actual matching and debugging process, on the one hand, it is necessary to understand the performance parameters of the transducer, and on the other hand, it is necessary to explore the matching conditions in actual work to achieve matching.