A sensorless control system for a permanent magnet synchronous machine, comprising: a counter electromotive force estimation unit configured to estimate a counter electromotive force of a permanent magnet synchronous machine using a phase current, which is applied from an inverter to the permanent magnet synchronous machine, and a phase voltage reference, which is applied to the inverter; and a speed estimation unit configured to estimate an angular velocity and an electrical angle of a rotor of the permanent magnet synchronous machine using the estimated counter electromotive force that is estimated in the counter electromotive force estimation unit, wherein the counter electromotive force estimation unit is further configured to: determine a state variable using the phase current that is measured from an output of the inverter and a d-axis and q-axis inductances in a synchronous reference frame, and estimate the counter electromotive force based on a weighted value, the phase current, and the phase voltage reference, wherein the weighted value is determined by comparing the estimated angular velocity with a reference angular velocity, characterized in that the counter electromotive force estimation unit is configured to determine the estimated counter electromotive force using the following Equation p x e ^ dqs E e ^ dqs = − J ω ^ r − I 0 0 x e ^ dqs E e ^ dqs + I 0 ν dqs e − R s i dqs e + L x dqs e − x e ^ dqs − 0 1 − K obs K 1 0 1 − K obs K 2 x e ^ dqs E e ^ dqs wherein L = K obs g 11 + 1 − K obs 1 T s ω ^ r − ω ^ r K obs g 12 + 1 − K obs 1 T s − g 21 0 0 − g 22 and wherein K obs is the weighted value, ^x e dqs is the estimated state variable, x e dqs is an state variable, ^ E e dqs is the estimated counter electromotive force, R s is a phase resistance of the permanent magnet synchronous machine, v e dqs is the phase voltage reference, i e dqs is the phase current, L is a gain of an observer, T s is a sampling time, I is an identity matrix, f J is an anti-diagonal 90° rotation matrix, and g 11, g 12, g 21 and g 22 are adjustable gains. a counter electromotive force estimation unit configured to estimate a counter electromotive force of a permanent magnet synchronous machine using a phase current, which is applied from an inverter to the permanent magnet synchronous machine, and a phase voltage reference, which is applied to the inverter; and a speed estimation unit configured to estimate an angular velocity and an electrical angle of a rotor of the permanent magnet synchronous machine using the estimated counter electromotive force that is estimated in the counter electromotive force estimation unit, wherein the counter electromotive force estimation unit is further configured to: determine a state variable using the phase current that is measured from an output of the inverter and a d-axis and q-axis inductances in a synchronous reference frame, and estimate the counter electromotive force based on a weighted value, the phase current, and the phase voltage reference, wherein the weighted value is determined by comparing the estimated angular velocity with a reference angular velocity, determine a state variable using the phase current that is measured from an output of the inverter and a d-axis and q-axis inductances in a synchronous reference frame, and estimate the counter electromotive force based on a weighted value, the phase current, and the phase voltage reference, wherein the weighted value is determined by comparing the estimated angular velocity with a reference angular velocity, characterized in that the counter electromotive force estimation unit is configured to determine the estimated counter electromotive force using the following Equation p x e ^ dqs E e ^ dqs = − J ω ^ r − I 0 0 x e ^ dqs E e ^ dqs + I 0 ν dqs e − R s i dqs e + L x dqs e − x e ^ dqs − 0 1 − K obs K 1 0 1 − K obs K 2 x e ^ dqs E e ^ dqs wherein L = K obs g 11 + 1 − K obs 1 T s ω ^ r − ω ^ r K obs g 12 + 1 − K obs 1 T s − g 21 0 0 − g 22 and wherein K obs is the weighted value, ^x e dqs is the estimated state variable, x e dqs is an state variable, ^ E e dqs is the estimated counter electromotive force, R s is a phase resistance of the permanent magnet synchronous machine, v e dqs is the phase voltage reference, i e dqs is the phase current, L is a gain of an observer, T s is a sampling time, I is an identity matrix, f J is an anti-diagonal 90° rotation matrix, and g 11, g 12, g 21 and g 22 are adjustable gains. ^x e dqs is the estimated state variable, x e dqs is an state variable, ^ E e dqs is the estimated counter electromotive force, R s is a phase resistance of the permanent magnet synchronous machine, v e dqs is the phase voltage reference, i e dqs is the phase current, L is a gain of an observer, T s is a sampling time, I is an identity matrix, f J is an anti-diagonal 90° rotation matrix, and g 11, g 12, g 21 and g 22 are adjustable gains.