| 摘要 |
A power calculating device including a control signal generating unit for generating a control signal. The control signal determines a power calculating period and an imbalance compensation period. The device also includes an input voltage changeover unit for changing over between a first voltage corresponding to a voltage of a system under measurement and a constant voltage under the control of the control signal to generate a second voltage, which is the first voltage during the power calculating period and the constant voltage during the imbalance compensation period. The device further includes a Hall element member for generating a third voltage corresponding to a product of the second voltage and a magnetic density generated by a magnetic field applied to the Hall element member. The device also includes an imbalance detecting unit for generating an offset compensation signal based on the third voltage, and a variable resistor connected to the Hall element member. The resistance value thereof is changed by the offset compensation signal, whereby an imbalance voltage of the Hall element member is compensated.
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