Guide to DC Motor Technical Parameters

Technical Information for Motor-Gearbox Combinations, ③, Guide to DC Motor Technical Parameters

• The following values are measured and calculated at nominal voltage under the temperature at 25 ℃

1、Technical words

2、No load current--I₀

The current consumed after stable under the rated voltage when there is no loaded. This parameter will be affected by different temperatures.

3、No load speed--N₀

The highest speed obtained after stable under the rated voltage.

4、Stall torque--T_s

Stall Torque is the torque produced by the motor whose output rotation speed is zero under the rated voltage. This parameter is highly effected by different temperatures.) step-by-step: 1. Basic relation: Ts​=Kt​⋅Is​. 2. Stall current: Is​=U/R. 3. Predictive model with friction: Ts​=Kt​×(U/R−i0​)

5、Stall current--I_s

Stall current is the current that the motor draws when its shaft if prevented from moving.

6、Maximum output power--P_max

The maximum output power of the motor at the rated voltage.

7、Maximum output efficiency--η_max

The maximum ratio of output power of the motor to the consumption of electrical power.

8、Back - EMF Constant--K_E(mV/rpm)

The constant corresponding to the relationship between the induced voltage in the rotor and the speed of rotation.

9、Torque constant--K_t (g.cm/A)

The constant corresponding to the relationship between the torque developed by the motor and the current drawn.) In SI units, the Torque Constant Kt​ ($N\cdot m/A$) and the Back-EMF Constant Ke​ ($V/(rad/s)$) are numerically equal.

10、Speed constant--K_n (rpm/V)

The speed variation per volt applied to the motor terminals at the constant load.

11、Mechanical time constant--t_m （ms）

The time required for the motor to reach a speed of 63% of its final no load speed, from standstil.

, R: (Static resistance), J: (Rotor inertia)