具有精确基准频率的数控半桥PWM输出调整电路

Adjustable Circuit of NC Half-Bridge PWM Output With Precise Reference Frequency

在超声换能器电源电路中,为能使超声换能器以一定的振幅谐振,必须精确控制振荡电路的频率及功放电路的输出功率.设计了一种具有精确基准频率控制的数控半桥PWM输出调整电路,利用DSP芯片TMS320F2812控制AD9833产生精确的基准频率信号,并结合数控电位器X9312和555定时器,实现数控调整PWM波形的占空比,达到精确控制输出信号的频率、功率的目的.为了能够驱动乙类功率放大电路,还研究了一个半桥变换电路将单路PWM波形变换为两路互补的PWM波形.

An adjustable circuit of NC half-bridge PWM output with precise reference frequency is described in this paper,which is used to make sure that the ultrasonic transducer can work on the resonant point precisely in power amplifier circuit.The precise reference frequency is generated by AD9833.In order to control the output power exactly,X9312 and 555 timer are combined to adjust the duty cycle of PWM,and one PWM signal is transformed into two complementary waves to drive power amplifier circuit of ultrasonic transducer.