Consumed power calculation method for electric motor and industrial machine
AssigneeThe Japan Steel Works, Ltd.
InventorRyo Okawachi
Life of this patent
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Abstract
A consumed power calculation method for an electric motor for calculating consumed power of the electric motor in an industrial machine including one or more electric motors supplied with a current and driven by an inverter, the consumed power calculation method including: measuring a current Im supplied to the electric motor; obtaining an output torque Tm of the electric motor based on the current Im; and calculating consumed power Wm of the electric motor by the equation: Wm=2π·Tm·Rm/(ηm·ηp)/60+Pw, where Rm is a rotational speed of the electric motor, ηm is a motor efficiency of the electric motor, ηp is a power factor, and Pw is a switching loss of the inverter.
Claims10
A consumed power calculation method for an electric motor for calculating consumed power of the electric motor in an industrial machine including one or more electric motors supplied with a current and driven by an inverter, the consumed power calculation method comprising:
- measuring a current Im supplied to the electric motor using a current sensor provided in the inverter;
- obtaining an output torque Tm of the electric motor based on the current Im;
- detecting a rotational speed Rm of the electric motor using a rotary encoder;
- and
- calculating, by a controller of the industrial machine, consumed power Wm of the electric motor by the following equation:
- Wm=2π·Tm·Rm/(ηm·ηp)/60+Pw,
- where ηm is a motor efficiency of the electric motor, ηp is a power factor, and Pw is a switching loss of the inverter.
An industrial machine comprising:
- one or more electric motors supplied with a current and driven by an inverter;
- and
- a control device configured to:
- measure a current Im supplied to the electric motor using a current sensor provided in the inverter;
- obtain an output torque Tm of the electric motor based on the measured current Im;
- detect a rotational speed Rm of the electric motor using a rotary encoder;
- calculate consumed power Wm of the electric motor by the following equation:
- Wm=2π·Tm·Rm/(ηm·ηp)/60+Pw,
- where ηm is a motor efficiency of the electric motor, ηp is a power factor, and Pw is a switching loss of the inverter;
- and
- display the consumed power Wm of the electric motor on the control device.
Dependencies are inferred from the claim text.