Using Conventional Method And Space Vector Pulse Width Modulation Technique For Ripple Reduction

TM4, the industrial partner, is a leading manufacturer and supplier of traction motors and drives for electric vehicle industry in Canada. As a drive manufacturer, they always aim to provide solution which is energy efficient with small footprint. In order to achieve this, they always look for alternative software and hardware solutions. Software modifications, which may improve the system performance in comparison to their existing drive control strategy without increasing the size of the system, are always sought after for continuous improvement of their system. In this regards, the internship is relevant to them for exploring alternative control strategies.

Figure 1: An example of PWM in AC motor drive. The smoothness of the resultant sinusoidal waveform can be controlled by the width and number of modulated impulses.

Using Field Oriented Control, current control is largely unaffected by speed of rotation of the motor[6].In the scheme of filed oriented control motor currents and voltages obtained from the motor are transformed into d-q reference frame. Measured currents from three stator phases these currents which are now in the stator reference frame are converted into two phase using Clarke transformations which are further converted into the corresponding rotor reference frame using Park transformation. The resultant current obtained is dc which is easier for the PI controllers to operate.

With the advent of modern controls theory and in the semiconductor technology, the use of high sophisticated technologies, advance digital controllers and embedded systems which include microprocessors, DSPs (digital signal processors), ASICs (application-specific integrated circuits), and FPGAs (field-programmable gate arrays).in the area of AC power control have become global challenges nowadays[1]. Recently FPGAs have become a good alternative answer and have been generally accepted as a tool for the controller`s platform in high performance embedded control system[2]. This device completely give inventors the ad-liberty to use their design customs

However, AC speed control was a challenging task. When precise speed control was required, the DC motor became a replacement for the AC motor, because of its efficient and economical means of controlling speed accurately. It wasn’t until the 1980s that AC speed control became a competitor. Over time, AC Drive technology eventually transformed into an inexpensive and reliable competitor to the traditional DC control. Now, an AC Controller is capable of speed control with full torque attained from 0 RPM through the maximum rated

Because of its linear characteristics and ease of controlling it's speed by simple power electronic circuit. The main obstacle for this type of system which has prompted the researchers to focus their studies toward AC machine, such as induction and synchronous machine. The availability of the variable speed drives for induction motor made it dominated in industry. Despite this, the small efficiency in induction motor especially those which have low power rating. The PMBDCM with predominant performance is found to be the solution for the drawbacks of the AC and Induction motors. The characteristics of the PMBDCM is similar to the separately excited DC motor, the difference in controller of PMBDCM which is the same of AC motor controller [2] [6].

A dc Brushless Motor uses a permanent magnet external rotor, three phases of driving coils, one or more Hall Effect devices to sense the position of the rotor, and the associated drive electronics. The coils are activated, one phase after the other, by the drive electronics as cued by the signals from the Hall effect sensors, they act as three phase synchronous motors containing their own variable frequency drive electronics. A simplified current controlled modulation technique for BLDC motors is presented.

D.C Motor is used for variable speed operation because in dc motor torque and flux that can be control independently and that is achieved by armature and field current control respectively. D.C motor has many advantages delivering high starting torque, ease of control and non linear performance. But due to certain disadvantage of dc machine such as mechanical commutator and brush holder required time to time maintenance [1] .So cost of the drive system is increases. But now D.C Motor is less used in industrial applications. Because of low cost, better performance and the requirement of maintenance is less as compared to D.C Motor it make the asynchronous motor advantageous in many industrial applications. SCIM are most widely used than all the rest of the electric motor as they have all the advantages of A.C Motors and are cheaper in cost as compared to slip ring induction motor. Because of absence of slip rings, brush maintenance duration and cost associated with the wear and tear of brush are minimized. Because of these advantages, the induction motor is used in element of most of the electrical drive system for all the conditions like starting, braking, change in speed and speed reversal. To achieve the maximum efficiency of the induction motor drive, so many techniques are developed in the last few years. Now a day’s high switching frequency converters are used for changing the frequency, phase and amplitude of the input to an A.C. Motor can be changed, hence the speed and motor torque can be controlled. With the help of power electronic it is possible to

Firstly the hybrid HVDC transmission system configuration is given. Next MMC description is given and then the control strategies for the rectifier and inverter is presented. Finally the performance of system under steady state and transient conditions is discussed with the help of MATLAB results.

In this chapter, an overview of the state of the art system of an induction motor is carried out. It looks at various induction motor control methodologies utilizing current and voltage control to control the flux and the torque of the dynamic system. Highlight of the current and future challenges of induction motor drives are presented. To do that, a general principle of induction motor drives is discussed first follow by phase controlled of induction motor drives, frequency controlled of induction motor, and vector controlled of induction motor.

Efficiency of any machine is the quantitative relation of output power and input power. The efficiency of induction motor is determined using the equation

AC drives are used in the industry on three phase motors. Three phase motors are highly preferable due to their high efficiency and high power outputs. The need to control these three phase motors speed, torque, and direction has led to the creation of the AC drive. AC drives come in all shapes and sizes with no two being the same. Being nonstandard the manual is necessary to properly program and wire the AC drive.

1) are derived first by algebraically solving the equivalent circuit shown in Fig. 2. These extreme values include maximum torque, maximum mechanical power, maximum power factor, maximum efficiency, and maximum electric power. It will be shown that the torque and mechanical power extrema can be expressed in analytical forms while the power factor, efficiency and electric power extrema need to be solved numerically. It will then be shown that these extrema can also be determined graphically using the circle diagram method. The circle diagram method is an old method but can still be found in some textbooks (e.g., [3]-[4]). The research into graphical methods for induction motor analysis is still active (e.g., [5][11]). One may consider that the circle diagram method is limited to qualitative evaluation because it cannot give accurate results. In fact, if the circle diagram method is carried out by a modern computer drawing tool that allows the user to draw geometric diagrams with parameters (i.e., coordinates, lengths, angles, etc.) to the accuracy of four decimal places, then the circle diagram method is able to give all the aforementioned performance extrema with required accuracy. Unlike the circle diagram method used in [10] and [11] that is based on the approximate equivalent circuit of induction machine and is limited to motoring mode of operation, the circle diagram method used in this paper is based on

Power electronic converters, especially DC/AC inverters have been extending their range of use in industrial application because they provide better system efficiency, reduced energy consumption and improved quality of power. The output voltage of inverter could be fixed or variable at a fixed or variable frequency and output waveforms are therefore made up of discrete values, producing fast transition rather than smooth ones [2]. The ability to

This paper investigates adjustable speed induction motor drive using 2-level and 3-level PWM.The result obtained is verified using Matlab simulation.This result compares the hamonic contect in between 2-level and 3-level by FFT analysis tool.To analyse the resulta a carrier based pwm was taken using 2- level and 3- level topology and a threephase bridge convetor with internally generated capability SPWM/SVPWM was intrduced. Carrier freqency18*60Hz, modulation index 0.9, output voltage freqency 60 Hz and ouput voltage phase 0 degre Was fixed. So corresponing to above values,the motor speed was 1800 rpm. Or 188.5 radian/sec, hence torque is 11.87Nm. A two pole squirrel cage motor was taken subjected to 400V dc source with modulation index0.9 prduces 220v rms.when motor starts, at 0.5s it reaches its steady speed 181 radian/sec or 1728 rpm. Now by discretizing the FFT tool displays the frequency spectrum of voltage and current waveforms. These signals are stored in workspace in the ASM structure with time variable generated by the Scope block. As my model is discretized, the signal saved in this structure is sampled at a fixed step and consequently satisfies the FFT tool requirements.It was observed that value of total harmonic distortion(THD) was 65.77 percent in 2-level and 35.11 percent in 3- level for SPWM invertor and 56.77 percent for SVPWM invertor.