Power Drive

AC Motors Details (and application) :

AC Motors - Multi-phase motors include For the operation of pumps including motors driving a third of electricity consumption in the world, fans, compressors, lift, and various types of machinery. AC asynchronous motor includes motor, which is operated as a common phenomenon depends on three power: Motor one rod (or other magnetic material suspended in a magnetic field) the work - that rotate independently, it will align with the area can. When the magnetic field moves or rotates, moving the box with the iron bar, getting the alignment. Spinner - a rotating magnetic field current supply to turn round a different one visit per pole pair can create together with fixed stator.

Transformer Action:

Rotor windings in the stator windings current induced by the current, the power source for rotating coils need to avoid direct connection is. Induction motor with a rotating secondary conclusion can be considered as an AC transformer.

Rotating fields:

Rotating magnetic field created by multi-stator windings are exciting phase. 3 in one of the following example, a curved pole (1 step pairs) as the current phase motor, passes its peak and starts declining, the river begins to weaken the associated application after completion, but currently too The next pole pair ring B (2 phase) and associated river rises. At the same time, former pole pair C (3 phase) and associated flow negative and will increase the conclusion (positive direction) is running through. Net effect is that a magnetic flux wave is created when a river created by stator pole from one machine rotates around the axis, in the frequency of applied voltage. In other words, north and south poles of a magnet rotating around the stator as the stator flow field around the rotation. Proportional to the size of the flow wave rotating MMF is applied. Back created by currents induced in rotor windings ignore the effects of EMF, flux density B is proportional to applied voltage.

Transformer Action:

Motor and power source is connected to the stator primary windings. Normally, there Rotor, which carry the secondary windings are no external connections. Instead, the small rotor windings circuited. When the stator windings, shorted secondary transformer action due to a current flows in the current windings. Rotor current amount of air gap (and relative to the rotor speed, the flux density B on the relative slip spinner is called, as we will see below). Rotor currents and wind induced flow produced by the difference between the stator current torque generated by the reaction. Rotors are several types. The most popular use of AC Motors "cage rotor" bars, fixed prices for the short circuit currents induced at the end of the path made of copper or aluminum bars are between senior rings. There may be rotating coils expensive commutator and end a potential source for this type of unreliability is a connection.

Torque generation (Motor Action):

When the engine is first turned to the rest rotor, rotor windings (head) due to transformer action is a current. A new way of seeing that the relatively slow rotation on flow through (initially stable) rotor windings, a current flow in the windings of the generator causes measures. When the rotor windings is currently flowing, motor action by conductors on the Lorentz force will enter into force. Reaction between the current impact of conductor rotor and air gap magnetic flux in the rotor rotate in the same direction as the rotating flow, as she was swept away by the wave flow. Like DC machine, torque in an induction motor and rotor flux density B T is proportional to current I encourage this type, = K1 T bi On a continuous basis where k1 is the number of stator's magnetic circuit configuration and the number of stages. Rotor speed because the engine makes strong actions described above, but how it does, relative motion between the rotating stator field and rotor spinning, reducing ladder. This in turn reduces the generator measures and the conductor rotor current and rotor torque like this. Area of rotor rotation speed, synchronous speed, known as zero torque on the rotor speed decreases approach. Thus, an induction motor never reach the speed can reach synchronous speed.

Slip:

Spinner and called rotating rotor and slip between the proposals is given by:

NSS =- n NS NS where S is the slip in RPM synchronous speed, and N is the rotor's rotational speed. As the rotor speed of the current spin and the rotor is proportional to the proposals, the existing rotor and thus torque, both directly proportional to slip. Rotor resistance is proportional to rotor current. Increasing rotor resistance, current and slip, a form of reduction in speed and torque control growth is possible with wound rotor motors. Added benefit is that increased investment growing rotor resistance and counter current torque is growing up, but all of these services provide, at the cost of complex design, rotor slip rings and rotor windings used for incredible.

Speed:

Synchronous speed is given by the Rpm: NS = 120 (f) P P phase per frequency f Hz where powerline and number of poles. P is a number, since the need for each one pole there is the South Pole. Motors with different number of rods following table for the engine speed shows different frequencies, are working with AC supply.

Rotor speed:

rpm () Number of poles 2 4 6 8 10 12

50 Hz frequency 3000 1500 1000 750 600 500

60 Hz frequency 3600 1800 1200 900 720 600.

The actual speed depends on motor drive is loaded. Increasing engine load caused the slow increase in the slip. A balance of speed regulating motor speed matches the engine torque load torque. This is what happens when just enough to slip the power supply provides the necessary torque.

Speed control Pole Change:

With several poles pole machines quickly change the speed control was easy. In conjunction with different numbers or poles set by switching speed can be achieved in a limited number. Variable rotor resistance Including the speed of motors, however, limited slip, but a separate section rotor resistance range can deny, but one with wound rotor induction motor can benefit many different designs. Variable frequency Region depends on the speed of motor rotation speed, the speed control of AC power supplied by the frequency change can be made in the engine. As most machines, including motor skills only for the maximum saturation flow down its operating range is designed with the highest density. Flux density B is given by: B k = V 2 F Where V is the applied voltage, supply frequency f and a constant K2 is based on the size and arrangement of stator poles. In other words, if the flux density is constant, volts per Hertz regularly. This is an important relationship, and the following results. For speed control, supply voltage frequency in tandem with the increase in machine optimal operating point is required, otherwise the flow will be different. Practical one based on frequency control voltage with the motor controller controlling supply so the motor will mean. The volts / hertz control is known as. Increase voltage without increasing the frequency with which the engine torque to reduce production in the river reduces the magnetic circuit. New system to reduce motor torque in relation to frequency is increasing will slip. This in turn has a large stator current flow, IR volt drop in the growth and copper windings I2R losses in the windings. Results of engine capacity is a major decline. Increasing the frequency will still continue, ultimately, stop the engine. Frequency without increasing voltage will increase because of the magnetic circuit material to sate. High current flow, windings and magnetic circuit Eddy current losses in high I2R losses by the excessive heat, and ultimately engine failure due to overheating. Increasing voltage will force synchronous motor in motion, because, as it drops to zero torque of the synchronous speed is more than vision. It as a common variable frequency inverter is available through. See more about speed controllers Also note that the current induced in the rotor flux density and in turn is proportional to flux density is proportional to voltage, torque and rotor current is the product of flux density voltage is proportional to the square of V. Generator Action When an induction motor speed above synchronous speed is forced to follow, more engine torque and slip of the load torque is negative, reversing rotor induced emf and rotor current. In this case, the machine act as energy generators will back the proposal. If excitement is removed stator voltage bus, a generation is possible because there can be no induced current in the rotor. Regenerative braking Thus, traction applications, regenerative braking is not possible under the one machine with a fixed frequency supply fed synchronous speed. But if one variable is applied by the regenerative braking frequency is the engine, means to reduce the frequency, so that a time may be slow engine speed. AC motors controlled by microprocessor may be a degree of fine and DC current to prevent regeneration, while one can almost do revive low speed quickly evaporates. Dynamic braking -- Motors involved quickly and arrest (and / or may vice opposite) is a pair of stars, which is counter rotating shafts with reversing. Known as "plugging is." Engine can be quickly, by AC supply and stop feeding the stator windings instead of one DC (zero frequency) supplied. With these two systems, energy resolution is not returned, but as the heat engine is engaged. These techniques are known as dynamic braking. Based Phase motors and synchronous motors include integrated himself nothing but a subsidiary or "sponge" on the rotor windings are address this issue as design modifications,. In general, an asynchronous motor is started 5 to 7 times the rated current speed and resume makes the first strong-EMF changes. Wound rotor motors, the current limited series starts rotor windings resistance increase, can. Cage design, to trigger electronic engine controls to prevent harm or the use of power supply are controlled. Even with control of the existing methods, motor overheat, as may still, however, may be limited at present set the pace is slow and pressure present, though reduced, will remain intact long one for a period. Power Factor Prepared by an induction motor current two components, voltage, the load transmission and inductive component, which magnetic circuit, the current load is currently running behind 90 ° magnetizing current is in phase with controls. Power factor Cosf, where F is currently applied voltage is defined behind the net late stage and the current phase components. Where V is voltage applied VAcosF pure electric load, given a current flows. Reactive power for the various methods used to reduce the existing gap in order to avoid losses due to poor power factor are for. Easiest appropriate size motor terminals is connected to a capacitor are connected. Since the current through a capacitor voltage, the capacitor has the effect of the catalyst element to compensate for motor current balance is canceled. Engine can also power factor improvement. Features One of the main benefits of induction motor that a commutator is not necessary. Motors involved, so strong are simple, reliable maintenance free and relatively low cost. They usually are constant speed devices whose speed is proportional to frequency residual. Variable speed motors one motor controller, with a variable frequency output is available. Application Step motors are used include, when the power supply depends on applying the National Grid Company. Because they are not commutators, they are suitable especially for high power applications. With load capacity from a few watts more than 10 megawatts are equipped are available. They are mainly used for industrial applications and for machine tools. In the past few years means that the availability of solid state inverter motors can be powered by a DC source. Electric and hybrid electric vehicles they now applications for use in motor vehicles are able. However, the difficulty of removing heat from rotor induction motor as most suitable for automotive applications, the performance problems involved in the extensive speed and power ranges, and a more expensive production through distributed windings. Permanent magnet and reluctance motors for these applications offer better solutions. Wound rotor induction motor Only historical interest now, these engines speed - torque characteristics of machine control permit has been developed. The rotor, which was accessible through slip rings used on the conventional windings. Rotor windings connected to supply, no current through the windings but may be connected in series with external winding controlled by rheostats. Modern electronic control these patterns is obsolete. Power Drive - AC Motors Details (and application) AC Motors Multi-phase motors include For the operation of pumps including motors driving a third of electricity consumption in the world, fans, compressors, lift, and various types of machinery. AC asynchronous motor includes motor, which is operated as a common phenomenon depends on three power: Motor one rod (or other magnetic material suspended in a magnetic field) the work - that rotate independently, it will align with the area can. When the magnetic field moves or rotates, moving the box with the iron bar, getting the alignment. Spinner - a rotating magnetic field current supply to turn round a different one visit per pole pair can create together with fixed stator. Transformer Action - rotor windings in the stator windings current induced by the current, the power source for rotating coils need to avoid direct connection is. Induction motor with a rotating secondary conclusion can be considered as an AC transformer. Rotating fields Rotating magnetic field created by multi-stator windings are exciting phase. 3 in one of the following example, a curved pole (1 step pairs) as the current phase motor, passes its peak and starts declining, the river begins to weaken the associated application after completion, but currently too The next pole pair ring B (2 phase) and associated river rises. At the same time, former pole pair C (3 phase) and associated flow negative and will increase the conclusion (positive direction) is running through. Net effect is that a magnetic flux wave is created when a river created by stator pole from one machine rotates around the axis, in the frequency of applied voltage. In other words, north and south poles of a magnet rotating around the stator as the stator flow field around the rotation. Proportional to the size of the flow wave rotating MMF is applied. Back created by currents induced in rotor windings ignore the effects of EMF, flux density B is proportional to applied voltage.

Transformer Action:

Motor and power source is connected to the stator primary windings. Normally, there Rotor, which carry the secondary windings are no external connections. Instead, the small rotor windings circuited. When the stator windings, shorted secondary transformer action due to a current flows in the current windings. Rotor current amount of air gap (and relative to the rotor speed, the flux density B on the relative slip spinner is called, as we will see below). Rotor currents and wind induced flow produced by the difference between the stator current torque generated by the reaction. Rotors are several types. The most popular use of AC Motors "cage rotor" bars, fixed prices for the short circuit currents induced at the end of the path made of copper or aluminum bars are between senior rings. There may be rotating coils expensive commutator and end a potential source for this type of unreliability is a connection.

Torque generation:

When the engine is first turned to the rest rotor, rotor windings (head) due to transformer action is a current. A new way of seeing that the relatively slow rotation on flow through (initially stable) rotor windings, a current flow in the windings of the generator causes measures. When the rotor windings is currently flowing, motor action by conductors on the Lorentz force will enter into force. Reaction between the current impact of conductor rotor and air gap magnetic flux in the rotor rotate in the same direction as the rotating flow, as she was swept away by the wave flow. Like DC machine, torque in an induction motor and rotor flux density B T is proportional to current I encourage this type, = K1 T bi On a continuous basis where k1 is the number of stator's magnetic circuit configuration and the number of stages. Rotor speed because the engine makes strong actions described above, but how it does, relative motion between the rotating stator field and rotor spinning, reducing ladder. This in turn reduces the generator measures and the conductor rotor current and rotor torque like this. Area of rotor rotation speed, synchronous speed, known as zero torque on the rotor speed decreases approach. Thus, an induction motor never reach the speed can reach synchronous speed.