| 摘要 |
A method of measuring current using a microprocessor (19) in a control system for operating solenoid-operated devices is provided in which the current is created by a PWM voltage (25). The method comprises the steps of sampling (27) the PWM based current signal at a frequency such that harmonics will fold to a set number of frequencies within a range of frequencies which the microprocessor can measure accurately, and filtering (28) the resultant signal to eliminate the set number of folded frequencies to obtain a clean, average and fast reacting signal which is representative of the measured current. |
