| 摘要 |
PROBLEM TO BE SOLVED: To cut down on the cost of a brushless DC motor by reducing its capacity to the minimum, securing durability of a switching element of a driving circuit of the motor. SOLUTION: Six switching elements U+, V+, W+, U-, V- and W- are alternately switched on/off in accordance with a rotor phase of the brushless DC motor M, and the rotor is rotated by alternately passing a current to a plurality of coils 37(U), 37(V) and 37(W) corresponding to the elements. Setting in advance the rotor phase as a startup-rotor phase, where the maximum torque is secured when a current is passed to the specified coils 37(U), 37(W) that correspond to the specified elements U+, W- of which the capacities are set larger than those of the remaining 4 elements V+, W+, U- and V-, the rotor phase shall coincide with the startup-rotor phase when the rotor ceases to rotate. The brushless DC motor M is started up by switching-on the specified switching elements U+, W- that correspond to the specified coils 37(U), 37(W). |
