Frequency sweep and frequency following control method for frequency of ultrasonic welding power source

Abstract

The invention discloses a frequency sweep and frequency following control method for frequency of an ultrasonic welding power source, comprising the following steps: Step 1, after an ultrasonic generator is turned on, an MCU controller controls an inverter to output certain initial working frequency through a driving controller; Step 2, the working current in an ultrasonic system is detected, andthe frequency sweeping operation mode is that the MCU controller controls the output frequency of the inverter to be f0+[delta]f; and Step 3, the working current in the ultrasonic system is detected.The method can realize the ultrasonic generator frequency tracking function, so that the ultrasonic generator can follow change in the equivalent capacitance and resistance of the ultrasonic generatorload with the operation, the inherent frequency of the ultrasonic acoustic system is caused to drift, the entire ultrasonic system is enabled to work in a resonant state, and the maximum power is output. The frequency sweep and frequency following control method is fast in real-time reflection speed, the circuit is simple, and the cost is relatively low.

Description

technical field [0001] The invention relates to the technical field of ultrasonic welding, in particular to a frequency sweeping control method for ultrasonic welding power supply frequency. Background technique [0002] The acoustic system of the existing ultrasonic welding machine is mainly composed of an ultrasonic generator, an ultrasonic transducer, an ultrasonic horn, and a welding head. During the welding process, due to the welding load and the temperature of the ultrasonic acoustic system, energy loss, welding area, welding head processing wear, etc., the equivalent capacitance and resistance of the ultrasonic generator load will change with the work, which will cause the ultrasonic acoustic system. The natural frequency drifts. If the power frequency of the ultrasonic generator does not follow the change, it will cause the ultrasonic system to no longer work at the resonance point, reduce work efficiency, and increase the loss of the transducer. Therefore, the ultr...

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Problems solved by technology

During the welding process, due to the welding load and the temperature of the ultrasonic acoustic system, energy loss, welding area, welding head processing wear, etc., the equivalent capacitance and resistance of the ultrasonic generator load will change with the work, which will cause the ultrasonic acoustic system. The natural frequency drifts. If the power frequency of the ultrasonic generator does not follow the change, it will cause the ultrasonic system to no longer work at the resonance point, reduce work efficiency, and increase the loss of the transducer. Therefore, the ultrasonic generator must have a frequency tracking function. Ensure that the frequency of the inverter trigger pulse in the ultrasonic generator follows the resonant frequency of the load

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