SM-A20758-A/3 7. References
61 2020-10-06
7. References
Operating principle of digital electro-pneumatic
regulator
Operating principle
The digital electro-pneumatic regulator performs feedback control to control the pilot pressure by
detecting controlled pressure using a pressure sensor, and PWM-driving two-port solenoid valves for air
supply and exhaust.
◼ Configuration of control circuit
◼ PWM drive
The pulse width modulation (PWM) is a form of electrical signal and controls the ratio of ON pulse width
time to OFF pulse width time in a certain period of time (Duty ratio).
Duty ratio = t/T × 100 (%)
◼ Relationship between PWM driving and controlled pressure
The set pressure and the controlled pressure are compared, and the solenoid valve ON time is varied
based on the difference between the pressures to control the pilot pressure so that the controlled
pressure equals the set pressure. A larger difference increases the Duty ratio and expands the solenoid
valve ON time. A smaller difference reduces the Duty ratio and shortens the solenoid valve ON time.
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