The permanent magnet synchronous motor drive requires two current sensors and one rotor position sensor to apply different control techniques to control the speed or position of the rotor. Generally, the rotor position is sensed by an optical encoder or detector for high precision applications. The cost of position sensors is approximately as same as the price of a low power motor, which means that the total system cost of such a drive is very uncompetitive compared to other types of motor drives. Of course, the price of the current sensors is not high compared to the rotor position sensor, and other electric drives also require current sensors to control the current. Therefore, the control and performance of the permanent magnet synchronous motor drive without a position sensor can also improve the application of this drive for cost-sensitive applications and can also be used as a control backup for sensor-based drives when the sensor is failed. Permanent Magnet Synchronous motors \\LTRfootnote{PMSM} are increasingly playing an important role in electric propulsion systems. Permanent magnet motors are used in the automotive industry, electric vehicles, submarines, home appliances, underground trains, as well as in areas where high speed and precision are required, such as CNC machines, sonars, fiber optics, robotics and automation systems. In order to successfully use a permanent magnet synchronous motor, it is necessary to know the speed and position information of the rotor. Usually, the rigs and industrial encoders that connect to these motor provide these information. At the same time, in many applications there is no use of these sensors for a variety of reasons, including volume and weight constraints, electromagnetic radiation and radio interference, as well as reliability concerns. Therefore, a new approach and attitude in the development of electrical drives, called sensorless methods have been developed. In some of these methods, the stator voltage and current are used to estimate the rotor position. There are three general strategies for estimating the position of the rotor in these motors, which are known as BEMF methods, signal injections and intelligent methods. Most of these methods have a poor performance at startup and in low speeds. Since the performance of BEMF methods is reduced at low speeds and standstill modes due to the lack of BEMF voltage in this range, in this thesis primarily have been focused on high-frequency injection methods to estimate the initial rotor position and then control the speed of the motor at low speed range. And after detecting the rotor's initial position and controlling the motor in a low speed range, the active Flux Observer Method will be used to control the speed of the motor higher speeds up to the base speed. .In this thesis, acoustic noise and losses caused by high frequency signal injections are investigated and a method is suggested to diminish these issues as much as possible. An appropriate switching function is also introduced to move from the low speed range to the high speed range and vice versa. Simulation results and practical tests are carried out in order to evaluate the method and these results are compared for a sensorless drive with a sensor. It is expected that the proposed method, along with the considerations considered in various research phases, including hardware design, software and drive controllers, can cover a wide range of motor speed control from zero to the base speed.