Mechanical characteristics of the brushless motor is refers to under certain conditions, the speed of the motor n and the connection between the torque T, reflects the motor torque as a function of speed change, usually by the mechanical characteristic of the motor to reflect. Brushless motors and dc motors with similar characteristic curve equation, thus with dc motor characteristic curve is very similar. We know that when a motor drive under certain voltage U, during which the energy conversion of available voltage balance equation: U = E + IR. The relation between the meaning of the said, the power supply voltage U is equal to the motor counter electromotive force and the sum of the voltage of the coil winding loss. To explain from the relation between the energy exchange of the motor and the mechanical behavior is very obvious, we provide the voltage for the motor to drive the motor, as a result of the energy loss, only part of the electrical energy to participate in the transformation, when the motor speed faster and faster, and the counter electromotive force produced by the motor coil on the consumption of voltage is equal to the sum of the power supply voltage, the motor to reach maximum speed. Motor ampere force and rotational rely on electromagnetic induction principle, counter electromotive force is proportional to the speed of the relationship, when the motor speed is very small, the counter electromotive force is small, the U = E + IR shows that U - E is very smallE is very big, so the condition of current I = (U -E)/ R will be very big, when speed faster and faster, counter electromotive force E is more and more big, the current is smaller and smaller with the rotating speed. A maximum moment of motor current in the counter electromotive force E for the moment, the rotating speed for the state, so the motor when blocked, the current is very large, so are easily destroyed. A brushless motor, although the current is inversely proportional to the speed, but the current is proportional to the torque of the relationship. When no inductive hypothesis motor, the relationship between the speed, current and torque into linear change, after a brushless motor with propeller, we push the throttle to a fixed point, the mechanical form of motor performance is a: + propeller rotor system starting from the static gradually accelerated, and reached the maximum speed and back into balance. We already know that in the process, speed increasing current in smaller and smaller at the same time, also it can be said that the torque in smaller and smaller, when the motor torque gradually small to is equal to the resistance torque of the load, motor balance, the greatest speed. , in turn, we will see, if you want to motor driven load, must be in the starting torque is greater than the load torque, otherwise, the motor will not start, it's like a small motor with propeller. , of course, in the actual power system, the motor's three-phase wire connected to the electric adjustable, equivalent series resistance of an external, the voltage of the motor will have a little pressure drop, will have an effect on characteristics of electric machinery, with modern power switch device technology is getting better and better, its pressure drop is very small effect.
