一种脉冲宽度调节方法及实验

A Method of Pulse Width Adjustment and Its Experiments

针对脉冲宽度调制波的采样信号频率和占空比分辨率相互耦合问题,提出了基于平均占空比的PWM波周期和占空比调节方法。实现占空比为N位的分辨率,将N拆分为计数位宽H和周期计数次数位宽L(N=H+L,L<N,H<N)。理论推导利用平均法在相同的调制波形周期下,实现相同分辨率的占空比,但可减小采样信号频率,便于低频率器件实现相同周期和分辨率的波形。利用STM32F103VET单片机和外置8 MHz晶振,在采样频率为1 MHz时,编程可实现占空比为12位分辨率,周期可调为250 us的脉冲宽度可调方波信号。采样频率仅为直接分频法输入频率的1/24,实验表明此方法可以在低频率信号下实现相同周期和占空比分辨率的方波信号。

Aiming at the problem that the frequency and duty cycle resolution of the sampled signal in pulse width modulation waveform are coupled with each other,a PWM wave period and duty cycle adjustment method based on average duty cycle is proposed.The duty cycle resolution is realized by splitting N into two parts:the count bit width H and the cycle count number bit width L(N=H+L,L<N,H<N).It is theoretically deduced that the duty cycle with the same resolution can be realized by averaging method under the same modulation waveform period,which can reduce the sampling signal frequency and facilitate the low frequency devices to achieve the same waveform with the same period and resolution.Using STM32F103VET single chip microcomputer and 8MHz crystal oscillator,the pulse width adjustable square wave signal with 16 bit duty cycle and 250us period can be programmed at sampling frequency of 1MHz.The sampling frequency is only 1/24 of the input frequency of direct frequency division method.The experiment shows that this method can realize the same period sum under low frequency signal.