频率自动跟踪超声波电源设计

针对超声波电源工作时负载状态改变,换能系统产生谐振漂移的问题,提出了一种基于STM32的频率自动跟踪超声波电源的设计。电源逆变电路采用带辅助网络的全桥结构,阻抗匹配电路选择了一种改进型的T型匹配网络,应用PWM移相调功技术控制电源的输出功率,通过数字鉴相技术得到电压电流的相位差作为电路谐振状态的反馈信号,结合STM32主控制器进行PI控制,调节PWM波的输出频率使电路始终工作于谐振状态,实现了谐振频率的自动跟踪。最后基于该设计方案,实际制作了一款应用于超声波清洗仪的电源,并通过实验验证了该电源具有输出功率稳定,负载适应性强,输出频率自动跟踪等特点。

Design of frequency automatic tracking ultrasonic power based on STM32

In view of the frequency drift problem in transducer system when the stage of load changes, a design of frequency automatic tracking ultrasonic power based on STM32 is put forward. The power inverter circuit adopted a full-bridge structure with auxiliary network, an improved T-type matching network is selected for impedance matching, and the constant power output of power supply is realized by PWM phase shift power technology. The phase difference of the voltage and current is obtained as the feedback signal of the resonant state of the circuit, and the PI controller is controlled by the STM32 main controller. The output frequency of the PWM wave is adjusted so that the circuit always works in the resonant state, and the resonant frequency is automatically tracked. Finally based on the design, a power supply for the ultrasonic cleaner is produced. The experimental results show that the power supply has the characteristics of stable output power, strong load adaptability and automatic tracking of output frequency.