In order to improve the efficiency, interior permanent magnet synchronous motors (IPMSMs) or the synchronous reluctance motors (SynRMs) need to be calibrated to obtain the maximum torque per ampere (MTPA) and flux-weakening (FW) curves. In industrial application, there are different types of IPMSMs and SynRMs. It is expensive and time-consuming to build test benches to calibrate each motor. In this letter, a physics-informed network is proposed to obtain the MTPA and FW operating curves. Only data from accelerating experiment, when motor operates without load, are adopted. The test bench is unnecessary. Experimental results show the validity of proposed method.

Spread-spectrum modulation strategy is recognized as an effective solution to reduce conducted EMI. This paper proposes a family of spread-spectrum modulation strategies that can effectively reduce conducted EMI for power electronics converters. The introduced modulation strategies eliminate the noise spikes in conducted EMI spectrum, reducing the harsh requirements for designing EMI filters. The proposed spread-spectrum methods are based on the distribution characteristic of switching frequency, which determine the waveform function of switching frequency. In addition, the design principles take reduced switching losses and fixed variation range of switching frequency into consideration. The differential equation that makes the switching frequency subject to arbitrary statistical distribution is derived in detail together with the corresponding solutions. Three typical statistical distributions represented by uniform distribution, exponential distribution and normal distribution are performed. Relevant experiments have verified that the proposed spread-spectrum modulation schemes can reduce the conducted EMI about 20dB. Finally, several other typical spread-spectrum modulation schemes such as random PWM, periodic PWM and programmed PWM are implemented in converters for comprehensive comparison to evaluate the proposed spread-spectrum modulation schemes

The increased phase number of multiphase systems enable us to exploit more degrees of freedom, such as the shape of phase carriers in pulse width modulation (PWM). The Sawtooth Carrier-based PWM (SCPWM) techniques are proposed in this paper to reduce Common Mode Voltage (CMV) in both the peak-to-peak amplitude and the changing frequency, and it can be easily extended to symmetrical multiphase two-level inverters with any odd phase number. Theoretical analysis reveals that the switching between mirror-symmetrical carriers within one phase narrows the range of the sum of switching states in all phases, which leads to the reduction of CMV amplitude. Meanwhile, the overlapping of sawtooth carriers' straight edges among different phases slows down the change of the sum of switching states, which results in the decrease of CMV changing frequency. Moreover, the effects of voltage harmonics injection and switches' dead-time settings on the CMV reduction performance under the proposed SCPWM techniques are investigated. Finally, the experiment results in a five-phase induction machine (IM) and multiphase RL loads verify the improved the CMV performance and the extensibility of the proposed SCPWM methods.

It is necessary to suppress the emission level of conducted EMI for power electronics converters, and variable switching frequency PWM (VSFPWM) is an alternative approach to reduce conducted EMI without adding bulky passive components. However, experimental results indicate that there are still many obvious spikes in spectrum for most modulation indexes, which makes the conducted EMI reduction for VSFPWM not as good as expected. In order to effectively suppress conducted EMI, this paper first investigates the cause of the spikes in spectrum for VSFPWM, and the analysis results show that the reason is the non-uniform distribution of switching frequency. Then, a novel PWM strategy called uniform distribution PWM (UDPWM) is proposed to eliminate the spikes in spectrum and greatly reduce conducted EMI. The design of UDPWM is based on the uniform distribution of switching frequency and the principle of less switching loss. The analytical formula of switching frequency is also deduced in detail, which is suitable for all conditions whatever the modulation index is. Finally, relevant experiments are carried out to validate the effectiveness of UDPWM in reducing conducted EMI and switching loss. UDPWM can approximately reduce conducted EMI by 20dB compared with CSFPWM, and all obvious spikes in spectrum are eliminated compared with VSFPWM.

Eccentricity can cause motor damage. It is necessary to obtain the degree of motor eccentricity for health management or eccentricity suppression. Due to the complex electromagnetic mechanism, it is hard to obtain the degree of motor eccentricity in traditional way. The neural network is suitable for obtaining the degree of eccentricity, but the eccentricity data are too few to train network. In this article, a data generation and quantitative characterization method for motor eccentricity based on improved generative adversarial network is proposed. The mathematical model is improved for pretraining, and the network and objective function are improved for data generation and eccentricity characterization. The results show the validity of the proposed method.

In ac–dc power conversion system, modular multilevel converter (MMC) has been a promising technology, especially for high-voltage application. In such kind of application, the common-mode voltage (CMV) generated by power electronic switching can cause damage to electrical components and increase the electromagnetic interference (EMI) to the system. Hence, this article proposes a modulation scheme to reduce the CMV of MMC applied in high-voltage system, such as high-voltage dc. Usually, MMC consisting of numerous submodules (SMs) adopts the nearest level modulation (NLM) with the low switching frequency, so the CMV of the NLM scheme is analyzed, which indicates that the peak value of CMV is one-third of SM voltage. If one more or one less SM is turned on compared with NLM, the CMV caused by modulation can be eliminated theoretically. Subsequently, a modulation scheme based on the nearest zero CMV vector (NZCMVV) to reduce CMV is proposed for MMC. The NZCMVV scheme utilizes the two adjacent levels as candidate levels, and the theoretical ZCMVVs are picked out. Finally, the ZCMVV closest to the reference vector is selected to approximately replace the reference. The proposed method is simple and easy to implement. Simulated and experimental results validate that the proposed scheme can reduce CMV and CM current compared with the traditional NLM method.