【摘要】 75kW超声波发生器的控制信号必须满足死区时间稳定,频率可调、稳定,能够间隙激发等要求。采用的是电压驱动型脉宽调制控制芯片TL494CN,其产生方波频率在15~40kHz范围内连续可调,死区时间为3μs。用NE555P产生调制波,该调制波信号与TL494CN产生的频率可调脉冲信号经调制后形成有间隙的方波信号,用于控制功率器件IGBT的驱动电路。从示波器记录的输出波形上可以看出:TL494CN生成的频率可调方波与NE555P产生的调制波经过调制电路后,得到能够间隙发射的控制信号。通过现场试验,该控制信号能够控制IGBT的驱动电路实现大功率超声的激发,且满足大功率超声激发的要求。更多还原

【Abstract】 The control signal for a 75kW ultrasonic generator must meet the requirements in the aspects of stable dead time,stable and adjustable frequency,excitation at intervals,etc.Considering these aspects,high-performance,a vol-tage-driven PWM control chip TL494CN is chosen to generate a square wave signal with continuously adjustable frequency from 15 kHz to 40 kHz and dead time of 3 microseconds.The modulation wave is generated by NE555P,which modulates the signal generated by TL494CN to form a square wave signal with regular intervals.Then the formed signal is used to control the driving circuit of power device IGBT.The field test proves that the control signal could control IGBT driver to achieve high-power ultrasonic transmission,and it satisfies the requirements of high ultrasonic power supply.更多还原