Speed Detection for Induction Motors Using Motor Current Signature Analysis

Single phase Induction machines have wide application in both industries and home appliances; hence the machine monitoring plays an important role for industries as well as domestic appliances for precise control. Electrical machine being the most sensitive part, various techniques are used to control the speed such as DTC (Direct Torque Control), Vector Control, Closed Loop Feedback Control etc. But these techniques have certain disadvantages like low resolution and reduced accuracy. Measuring the speed of an induction motor is possible by Tachometer. But in places where the motors are fixed at a remote place or inaccessible locations, tachometers cannot be used. In such conditions speed sensors are to be used which needs additional gadgets. In order to measure the speed of motors located in remote places the motor current is sensed using current sensor and the current signature is analyzed using software program. This Motor Current Signature Analysis (MCSA) method of speed sensing gives an accurate value of the speed of the motor. In this project, the current of a single phase induction motor is sensed and analyzed. The actual speed of a machine can be determined at the motor control center, remote from the machine. This may be subsequently used for speed control or protection.