is the most widely used motor three-phase asynchronous motor, using the three-phase alternating current (ac) of a rotating magnetic field to drive the rotor rotation. Most of the world's extra voltage three-phase asynchronous motor is fixed, in our country, for example, is 380 v three-phase alternating current. So in use, it is not rendered other voltage of the motor.
of course, you can shake the grid's influence on the motor into consideration, but at 3000 RPM three-phase asynchronous motor, rotating magnetic speed grid shake thoroughly to neglect.
but as for the problem the main problem is actually touched the mechanical properties of the motor. The so-called & other; Power & throughout; Is about the motor torque, torque formula is: T = 9550 p2 / n. Formula of P2 refers to the mechanical power of motor output, than the electrical motor USES a slightly smaller, so the theoretical voltage progress, is to be able to progress the electrical power that progress mechanical efficiency of the motor, and P2 and torque T is proportional to the, in theory, motor torque will increase. In practice production, of course, is forbidden to do so, always work under the additional voltage, motor with extra power operation. Operation condition for safe about motor is the most important thing. other may question the need to ask the motor starting time than operation occurs when a larger torque? Indeed, the starting torque is greater than the additional torque, but bigger torque means more power, can produce a serious problem, is increasing power, current also increases. Practice on regulating motor power is based on changes to the current and not voltage changes. As I said earlier, the motor want to additional power under extra voltage operation. So in use in the practical operation of three-phase alternating current (ac) different connection to alter the power of three-phase asynchronous motor, in order to switch motor starting and running condition, of course also can choose series reactance and other means to change the starting current.
voltage and current, and is a positive correlation. Due to the motor windings are rational elements, so can't directly to use ohm's law, simply contact general motor winding on the voltage and current can be expressed in the following formula:
is more than the ohm's law a flux relative differential item of time change, represents the origins of the counter electromotive force (Flux is equal to the product of inductance and current, so the differential item can, this is due to the different principles of motor can be decomposed into current change with time of commutation and inductance change with bearing motional emf and so on. 。 。 ）。 Not bound to the existence of the counter electromotive force formed voltage and current as ohm's law to comply with the same linear relation, but the current is still be voltage control, manipulation of the current is through the implementation of the control voltage. 。 。 Will not render to current constant and increase the voltage of the
other power is equal to the product of current and voltage that only exist in a purely resistive circuits, ohm's law applies on the motor current and the voltage of the product is called the apparent power, model aircraft, motor and motor to the output of power real called active power, even completely neglect cost, active power is less than the apparent power, as a result of the motor winding is a very typical inductive components, part of energy can thus be spooled in the electric field and magnetic field (Such as magnetic can is the product of the flux and current)Some of this energy is also can be used to do work, but others will also return to the power supply side. So practice the output power of the motor is smaller than the product of current and voltage. 。 。 You can imagine inductance as a dam, the upstream flow is the apparent power input, low flow rate is the active power output. There will always be part of the water will be trapped and storage, plant protection unmanned aerial vehicle (uav) motor, the storage of water is after the part is still to dirty, some are likely to be the origin of upstream water evaporation from the cloud.
