How is torque related to current and power?
The torque is the product of the flux and the torque-producing current, i.e. the component of current which is in phase with the voltage. In DC motors and AC induction motors, the magnetising current is usually constant regardless of torque, unless a special energy-saving control is applied at reduced torque.
Is the magnetising current always constant regardless of torque?
In DC motors and AC induction motors, the magnetising current is usually constant regardless of torque, unless a special energy-saving control is applied at reduced torque. For a small induction motor the magnetising current can be a considerable proportion (e.g. 70%) of the rated current.
How is the torque of an AC motor determined?
Motor current. In an AC motor without a permanent magnet, the flux amplitude is set by the ratio of the applied voltage to the frequency. The torque is the product of the flux and the torque-producing current, i.e. the component of current which is in phase with the voltage.
How are current and voltage related to torque and speed of a brushless?
The relationship between a motor’s electrical characteristics and mechanical performance can be calculated as such (note: this is the analysis for an ideal brushed DC motor, but some of it should still apply to a non-ideal brushless DC motor). A DC motor can be approximated as a circuit with a resistor, and voltage back-emf source.
How does the RPM limit affect the torque?
In that sense the RPM limit is down to how well the engine is made and what it’s made of rather than any fundamental EM properties. The torque is dependant on how large a magnet field the engine generates, and this is mostly dependant on the current it draws and the number of turns in the coil.
What’s the maximum torque of an electric motor?
As you can see from the graph speed and current are linear functions of torque so you might need only two measurements to draw these graphs. Efficiency and power will need more data. Usually for small motors maximum power is at 50% of stall torque (approximately 50% of no load speed).