Suppression of common-mode voltage in a PWM rectifier/inverter system

This paper proposes a PWM rectifier/inverter system capable of suppressing not only supply harmonic currents but also electromagnetic interference (EMI). An active common-noise canceler (ACC) developed for this system is characterized by sophisticated connection of a common-mode transformer which can compensate for common-mode voltages produced by both PWM rectifier and inverter. As a result, the size of the common-mode transformer can be reduced to 1/3, compared with the previously proposed ACC. A prototype PWM rectifier/inverter system (2.2 kW) has been implemented and tested. Some experimental results show reduction characteristics of the supply harmonic current and EMI</p

Implementation and position control performance of a position-sensorless IPM motor drive system based on magnetic saliency

This paper describes position-sensorless control of an interior permanent magnet synchronous (IPM) motor, which is characterized by real-time position estimation based on magnetic saliency. The real-time estimation algorithm detects motor current harmonics and determines the inductance matrix, including rotor position information. An experimental system consisting of an IPM motor and a voltage-source pulsewidth modulation inverter has been implemented and tested to confirm the effectiveness and versatility of the approach. Some experimental results show that the experimental system has the function of electrically locking the loaded motor, along with a position response of 20 rad/s and a settling time of 300 ms</p

Circuit configurations and performance of the active common-noise canceler for reduction of common-mode voltage generated by voltage-source PWM inverters

This paper discusses two different circuit configurations of the active common-noise canceler (ACC) which has been proposed by the authors. One is characterized by its DC power supply isolated from the DC link of a PWM inverter. The configuration makes it possible to integrate the ACC with a medium-voltage PWM inverter. The other compensates a partial frequency component of the common-mode voltage. The purpose is not to achieve complete cancellation, but to restrict only a slope in a change of the common-mode voltage applied to an AC motor. As a result, the core size of the common-mode transformer used in the ACC becomes considerably small. Experimental results show good effects of the proposed active circuits on both ground current and conducted EMI</p

An approach to real-time position estimation at zero and low speed for a PM motor based on saliency

This paper presents a magnetic saliency-based position estimation approach for a permanent magnet (PM) motor fed by a voltage-source pulse width modulation (PWM) inverter. The proposed real-time estimation algorithm detects motor current harmonics and calculates the inductance matrix, including rotor position information. Position estimation can be performed every period of PWM or carrier cycle. An experimental system using an interior permanent magnet (IPM) synchronous motor has been constructed. Experimental results verify that position estimation within 10° in electrical angle is obtained at standstill and at speeds as low as 1 r/min by the proposed approach</p

Analysis and reduction of EMI conducted by a PWM inverter-fed AC motor drive system having long power cables

This paper analyzes conducted EMI generated by a PWM inverter-fed induction motor drive system. It is shown experimentally and analytically that resonant phenomena in a high-frequency range beyond a dominant resonant frequency are originated from the behavior of power cables as a distributed-constant circuit. Spectra of common-mode and differential-mode currents are simulated by means of introducing a distributed-constant model of the power cables, which consists of a 20-step ladder circuit. As a result, it is also shown that these resonances can be damped out by a single common-mode transformer (CMT) and three differential-mode filters (DMFs), both of which have been proposed by the authors</p