基于PWM的直流模拟量隔离传输电路

DC Analog Isolation Transmission Circuit Based on PWM

普通光耦受其传输特性影响不适合直接传送直流模拟信号。它一般用于传送数字信号。根据光耦这一特点,提出一种使用脉宽调制技术将直流信号转换成数字波形进行隔离传输的电路。该电路能自动跟踪待传输的直流模拟信号,控制P89LPC901产生12位精度的占空比可调的PWM波,再经光耦隔离后送入低通滤波电路获取直流信号。此电路传输精度高,已用于某型电器设备检测装置中。运行一年多来,性能稳定可靠。

Ordinary optocoupler effected by the transmission characteristics is not suitable for direct transmission of DC analog signal.It is generally used to transmit digital signals.According to this characteristic of the optocoupler,the isolation transmission circuit using pulse width modulation technology was introduced,which converted DC signals into digital waveforms.The circuit can automatically trace DC analog signal prepared to be transmitted,and control P89LPC901 to generate the variable duty cycle PWM wave for 12-bit accuracy.The digital waveforms passed through optocoupler,then were to be sent into low-pass filter to obtain DC signal.The circuit has high transmission accuracy and is used for a certain type of electrical equipment detecting device.Running more than one year,its performance is stable and reliable.