Technical performance of high-speed switch digital valve

Technical performance of high-speed switch digital valve

The static characteristic (control characteristic) curve of pulse width modulated digital valve is shown in Figure 24. It can be seen from figure 24 that the control signal is too small to drive the valve core, and when it is too large, the valve is always in the pull in state, so there are start pulse width and end pulse width restrictions. The starting pulse width corresponds to the dead zone and the ending pulse width corresponds to the saturation zone, which determine the actual working area of the digital valve. If necessary, the dead zone or saturation zone can be eliminated by the control software or the hardware structure of the amplifier. When the sampling period is small, the maximum controllable flow is also small, which is equivalent to improving the resolution.

The dynamic characteristics of PWM digital valve can be measured by its switching time. Because the displacement of the valve core is difficult to measure, the switching time of the valve core can be obtained by controlling the turning point of the current waveform. Figure 25 shows the response curve of the pulse width modulated digital valve. Its dynamic indicators are the minimum opening time ton and the minimum closing time toff, which are generally equal by adjusting the return spring. When the valve core is fully opened or closed, the current waveform generates an inflection point, which can determine whether the valve core reaches the fully open or fully closed position, so as to obtain its switching time. When controlled by different pulse width signals, the dynamic index is also different.