| 摘要 |
PROBLEM TO BE SOLVED: To improve the current command value following-up ability of a linear motor by reducing thrust variation by giving a plurality of current command values having driver phase differences to the motor based on relative positional information, and connecting coils and drivers to each other in such a way that their polarities are inverted for each in-phase coil. SOLUTION: A controller G decides the current command values A and P, which are made to flow from current drivers D1 and D2 from the value of an absolute encoder F and outputs the values A and B. A magnet group M is magnetized so that a thrust variation may become the minimum, when current relation between coils in two phases is a sine wave having a phase difference of 90 deg., and makes the output of the absolute encoder E zero when the center of a mover M is positioned at the center of a coil Cn. The controller G selects two coils to be conducted, based on the value of the encoder E and turns on or off the corresponding relays -Rn-2 to Rn+2. The current drivers D1 and D2 generate currents so that the actual currents become equal to the command values A and B. Since the total of thrusts generated by each coil from the current of the driver D2 becomes the same as the thrust when current is made to flow into one coil, no variation in thrust occurs. |
