Views:27 Author:Site Editor Publish Time: 2019-09-06 Origin:Site
Ultrasonic generator (or power supply) is a device used to generate and provide ultrasonic energy to the ultrasonic transducer to work at the resonant frequency. According to its excitation mode, it can be divided into two types: one is other-excitation mode, the other is self-excitation mode. The other-excited ultrasonic generator mainly consists of two parts: signal generator in the front stage and power amplifier in the back stage. Usually, the ultrasonic energy is added to the ultrasonic transducer by coupling the output transformer. The self-excited ultrasonic generator connects the signal generator, power amplifier, output transformer and ultrasonic transducer into a whole, forming a closed-loop loop, which enables the whole ultrasonic generator to generate enough power through amplitude and phase feedback, so that the ultrasonic transducer can automatically maintain resonance on the mechanical resonance frequency.
With the rapid development of science and technology, power electronic devices have developed rapidly. So far, many power electronic devices with different principles and characteristics have been developed. One device determines the generation of power electronics technology. The development of ultrasonic generator is also inseparable from the development of power electronics devices, and to a certain extent, with its development. According to the types of devices used in the final stage power amplifier of the ultrasonic generator, we can see several stages of its development：
1. The early products used electronic tubes, and then developed to thyristor inverted ultrasonic generator. They have many shortcomings and have been eliminated.
2. Transistor type ultrasonic generator. All kinds of OCL and OTL power amplifier level circuits are suitable for the ultrasonic generator. The circuit is mature and the cost is low, but the volume is large and the weight is heavy. It is difficult to adjust to the frequency resonance point of the ultrasonic transducer. The output power is limited by the power transistor and can not achieve the desired effect. It is not easy to use modern digital methods, only in low power (less than 200W) applications.
3. Power module ultrasonic generator. By adjusting the duty cycle of the switch to control the output power, it has low power consumption, high efficiency, small size, light weight, good reliability, easy to use digital control. According to the type of switch used in power module, there are two main types:
a. Using power MOS transistor as switching device, according to its own switch, it has the following advantages: high switching frequency (100KHZ-1MHZ), good breakdown resistance (no avalanche effect), simple driving circuit, shortcomings are high on-resistance, limited by current capacity, not achieving full power output, output power is not enough. Meaning, the application industry is not wide.
b. IGBT is used as switching device. It is used in ultrasonic generator with switching frequency of 20-50 kHz and high power (over 1500w).
Main Performance Characteristics of Ultrasound Generator :
Electron Tube Generator
Power Module Generator
Degree of automation