What is the feedback signal of the ultrasonic generator?
The ultrasonic generator generates a signal of a specific frequency. This signal can be a sine signal or a pulse signal. This specific frequency is the frequency of the ultrasonic transducer. Generally, the ultrasonic frequencies used in ultrasonic equipment are 25KHz, 28KHz, 35KHz , 40KHz; 1OOKHz, frequencies above 100KHZ have not been widely used, but with the continuous development of technology, I believe that the use of it will gradually expand. A relatively complete ultrasonic generator should also have a feedback link, which mainly provides feedback signals in two aspects:
The first is to provide the output power signal, we know when the voltage of the ultrasonic generator changes. The output power of the ultrasonic power supply will also change. At this time, it is reflected in the ultrasonic transducer that the mechanical vibration fluctuates, which causes the cleaning effect to be unstable. Therefore, it is necessary to stabilize the output power, and adjust the power amplifier accordingly through the power feedback signal to make the power amplification stable.
The second is to provide frequency tracking signals. When the ultrasonic transducer is working at the resonant frequency, its efficiency is the highest, and the work is stable. The resonant frequency of the ultrasonic transducer will change due to assembly reasons and work aging. Of course, the frequency of this change is only a drift, not a change. Very large, the frequency tracking signal can control the signal ultrasonic power source, so that the frequency of the signal ultrasonic power source can track the resonant frequency point of the ultrasonic transducer within a certain range. Let the ultrasonic power supply work in the best state.
The ultrasonic generator is divided into self-excitation mode power supply and other excitation mode power supply according to the design. The self-excited circuit has no signal source, but integrates the oscillation, power amplifier, output transformer and transducer into a whole to form a closed loop. The loop meets the amplitude and phase feedback conditions to form an oscillator with power amplification. And it resonates at the mechanical resonance frequency of the transducer. Generally used in small devices with a small number of ultrasonic transducers; but for a large number of ultrasonic transducers, it cannot be debugged to achieve the resonance effect. Therefore, most of the ultrasonic generators of industrial ultrasonic cleaning equipment use other excitation methods. The generator of the ultrasonic welding machine generally adopts a self-excited ultrasonic generator.