| 摘要 |
PROBLEM TO BE SOLVED: To enable a current flowing through a motor to be measured at a low cost.SOLUTION: A current measuring device includes: a detection unit that measures a first current flowing through a motor, and detects, as a first signal, a first voltage indicating a second current obtained by combining currents flowing through respective phases of the motor; a smoothing unit that generates a second signal by smoothing the first signal; an amplifying unit that includes a first input terminal for inputting the second signal, a second input terminal connected to a first resistor and a second resistor for determining an amplification rate respectively, an output terminal for outputting a third signal obtained by amplifying the second signal on the basis of the amplification rate, a first power supply terminal connected to the ground, and a second power supply terminal connected to a first power supply; and an input unit that inputs a second voltage into the first input terminal. The current measuring device stores a third voltage indicated by the third signal when the motor is stopped, obtains a fourth voltage indicated by the third signal when the motor is rotated, and calculates the first current on the basis of a difference between the third voltage and the fourth voltage.SELECTED DRAWING: Figure 1 |
