Simplified Input Voltage Sensorless Vector Control for PWM Rectifiers

A conventional input-voltage sensor-based vector-controlled PWM rectifier is used in wide range of applications due to its well-known control structure, simple design, and good dynamic performance. Many existing input voltage sensorless methods have a control structure significantly different from that of conventional vector control, involving additional computational and design efforts. This article proposes a simplified input voltage sensorless control which has the same control structure as that of vector control and can utilize similar controller design procedure. The input voltage required for a phase-locked loop (PLL) is estimated from the current controller output using a simple algebraic equation. The sensorless PLL, so obtained, is mathematically modeled, and its frequency response is shown to be similar to that of a sensor-based PLL. The performance of the proposed method is compared with those of existing methods in terms of input power factor, response to distorted input voltage, sensitivity to system parameter, and computation time requirement through simulations and experiments. Apart from having the lowest computation requirement, the proposed method is shown to achieve the sensorless operation without any performance degradation, compared to the sensor-based operation, and with robustness to parameter variation. The proposed method includes a start-up procedure, which ensures low starting transient current.