METHOD OF LIMITING A POWER SUPPLY CURRENT AND OPTICAL DEVICE

摘要

The present invention relates to a method of limiting a power supply current in a system comprising a power supply (10), a motor (12) operating at different speeds, a driver (14) for driving the motor and a controller (16) for controlling the driver, the method comprising the steps of: specifying a first value that is related to a maximum power supply current (IPSmax); determining a second value that is related to an electromagnetic force-dependent voltage (VEMF) of the motor; determining a desired third value (Cdes) that is related to a desired motor current (IMdes); determining a first boundary value (a) and a second boundary value (b) for the third value, taking into account the first value and the second value; comparing the boundary values (a) and (b) to the third value (C des); and setting the third value in dependence on the result of the comparing step.