Power factor of induction motor pdf

The role of static power converters in the motor control in industrial and domestic applications has grown rapidly in which power can be manipulated with high efficiency so in most of the applications AC machines are preferable to DC machines.

The three-phase induction motors have some advantages in the machine efficiency, power factor, and torque ripples compared to their single-phase counterparts [1]. Though the precise control of single phase induction motor is less complex in comparison to the three phase induction motor, but when the torque requirement is considered then three phase induction motor is the best choice.

These motor drives are considered efficient as long as the power factor is above 0. But in practical motor drives application the power factor is low [2]. Due to this low power factor in motor drives system following disadvantages occurs, large KVA rating of the machine, greater conductor size, large copper loss, poor voltage regulation, reduces the power handling capacity of the system.

In this work power factor correction method is developed and adopted to improve the power factor. This power factor correction circuit mainly contains DC-DC converter and pulse width modulation current controller. Here we are using a boost DC-DC converter for power factor correction circuit to improve the input power factor nearer to unity [3, 4]. The boost regulator operates under continuous conduction mode and it produces lowest level of conducted noise and gives best input current waveform.

So, the boost converter is an excellent choice for a power factor correction circuit. In this work first converted single phase line voltage AC into DC. This DC is regulated by boost DC-DC converter and maintains a constant current waveform by using power factor correction circuit[5].

The developed hardware is tested on a 3-phase, 1. According to the requirement, a software program is written and is fed to the digital signal controller dsPIC30F for necessary action. The drive is operated under different loads No Load, Half Load and Full Load implementing without and with power factor correction Techniques.

The input power factor is nearer to unity at all Loads using power factor correction technique. The total harmonic distortion of three phase rotor currents has decreased and hence power factor increased for all the loads. Overall the performance of the drive is improved by using power factor correction technique when compared without power factor correction technique. All rights reserved by www. It has full bridge rectifier and filter capacitor, PFC circuit, full bridge inverter, control circuit.

A digital signal controller dsPIC30F is used to implement the core of the control function, which simplifies the hardware setup. The output of the rectifier is taken as actual signal and output of the boost converter taken as a reference signal to the Power Factor Correction circuit. In this PFC method, the reference current and actual current are compared in the comparator an error signal is generated. This error signal is amplified and compared to a fixed frequency carrier wave to generate the pulses to the IGBT All rights reserved by www.

The energy that a switching power converter delivers to a motor is controlled by Pulse Width Modulated PWM signals applied to the gates of the switches. It also consists of two opto-coupler for isolating the control and power circuits. C language is used to develop the program. In this work V, 50Hz, 3-Ph, 1. The hardware set is developed and tested in power electronics laboratory and the photograph of complete setup is shown in Fig 3. The test is carried out on induction motor for different loads and voltages.

For different loads and voltages, power, power factor and voltages across all lines are noted and are tabulated. Table 3. The corresponding waveforms and gate pulses are shown in Fig 3. The Table 3. From the Table 3. After the rectification that voltage is V, output power consumption is W with corresponding power factor 0. Experimental result for without power factor correction technique and with power factor correction technique at 1kg load with rpm speed Table - 3. From the Table3.

Experimental result for without power factor correction technique and with power factor correction technique at 2kg load with rpm speed Table - 3. There are many benefits to having power phase AC induction motors are the prime movers for the factor correction. At no load induction motor has very low power factor. It improves at increasing load from no load to full In an ac circuits there is generally a phase difference between load.

Power factor correction is achieved by the addition voltage and current. The term is known as power factor of capacitors in parallel with the connected motor circuits of the circuit. If the circuit is inductive, the current is lags and can be applied at the starter, or applied at the behind the voltage and the power factor is called lagging switchboard or distribution panel.

Keywords— Induction motor, simulation, power factor, The average power in an ac circuit is expressed in terms of rms power factor correction etc. This can be achieved by decreasing the network losses and improving the main electric load operation to a better efficiency level.

The designed scheme is concerned with improving the power factor of the distribution network by adding shunt capacitors to the network at optimal size and location. Industrial power distribution networks encounters increase in power losses and increase in the type of load is accompanied with low power factor which leads to huge transfer of reactive power from the Fig 1 Power factor triangle in terms of power utility through the network.

The main drawback of this problem is increase in the network losses and reduction in the voltage level. It can result in poor reliability, safety problems From the figure and higher energy costs. The actual amount of power being used or dissipated in a circuit is called true power.

The linear combination of true power active power to the apparent power. This is perfectly and reactive power is called apparent power. Power system general definition and can be applied to all cases. The power factor that is less than one. Power factor capacitive current then furnishes the excitation and may cause correction may be applied either by an electrical power serious overvoltage or excessive transient torques. Low power factor is an issue, which can be solved by adding power factor correction capacitors to the plant distribution system.

Capacitors work as reactive current generators "providing" needed reactive power KVAR into the power supply. By supplying their own source of reactive power, the industrial user frees the utility from having to supply it, and therefore the total amount of Fig 2 Current components of an induction motor [22] apparent power supplied by the utility will be less. The magnetizing current does not actually contribute the power factor level.

It is the catalyst that allows the motor to work properly. The induction motor therefore the power drawn by the motor, but will contribute to the power must operate at a lagging power factor. This power factor is dissipated in the supply and distribution system. The presence of air-gap between the stator and rotor of an induction motor greatly increases the reluctance of the magnetic circuit.

Consequently, an induction motor draws a large magnetizing current Im to produce the required flux in the air-gap. Therefore, the induction motor takes a high no-load current lagging the applied voltage by a large angle.

Hence the power factor of an induction motor on no load is low i. Typically, same.