| 摘要 |
PROBLEM TO BE SOLVED: To regulate accurately electric current passing though an electromagnetic coil 32 of an electromagnetic pressure controller 23 in a compressor 2. SOLUTION: In an electronic controller 14, impedance of the electromagnetic coil 32 of the electromagnetic pressure controller 23 is estimated (step S190), and a duty factor DT(n) for controlling the current passing through the electromagnetic coil 32 is calculated on the basis of the impedance (step S200). A voltage is applied to the electromagnetic coil 32 so that the rate of voltage-application time per unit time becomes a duty ratio. The impedance is estimated by using a time constant that is set so as to change in accordance with change in temperature of the electromagnetic coil 32. As a result, calculation can be performed for a time constantτ, an impedance, and a duty ratio in correspondence with temperature of the electromagnetic coil 32 in the present condition. Thus, the electric current passing through the electromagnetic coil 32 of the electromagnetic pressure controller 23 is approximated to a control current In of a command variable. COPYRIGHT: (C)2009,JPO&INPIT
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