| 摘要 |
<p>PULSE WIDTH MODULATED CONSTANT CURRENT SERVO DRIVER A method and apparatus for controlling a coil operated hydraulic valve employs a constant current source to consistently control valve response irrespective of variations in power supply voltage and coil resistance. A switching circuit controls the delivery of constant current pulses from the current source to the coil in accordance with a series of pulse width modulated control signals whose duty factors are proportionate to preselected values of hydraulic output pressures developed by the valve. A voltage regulator circuit provides regulated supply voltage to the constant current source in order to reduce variations in the coil current at small pulse widths.</p> |
