High Density EMI Filter Design in High Power Three-Phase Motor Drive Systems

High density EMI filter is important in the application of more-electric-aircraft (MEA). In this work, the author is focusing on several major aspects of EMI filter design that would influence the power density. In Chapter 1, the feature of EMI study and conventional design methods are reviewed. The interaction between the common-mode (CM) and differential-mode (DM) noise is one key factor introducing unnecessary weight to EMI filter design. In Chapter 2, the author explains the origin of the mixed-mode (MM) noise on the output side of three-phase motor drives. Experimental results have verified the existence of the MM noise in three-phase motor drives and its impact on power density. In Chapter 3, the noise mode transformation (NMT) in three-phase motor drives due to system impedance unbalance is discussed. Simulation and experimental results show that the NMT will cause EMI filter overdesign if not considered during the design stage. In Chapter 4 the author discusses the possibility of adding a CM inductor at the motor front and chassis end to reduce CM EMI filter weight. Experimental results show that the motor-end filter is effective in attenuating low frequency noise and has the benefit of being light weight comparing with the traditional three-phase CM choke. Cooling of the filter is of great importance in high power systems. In Chapter 5, a practical liquid-cooling design procedure for EMI filters in high power motor drives has been discussed. Potting and thermal modeling are analyzed. Thermal test results verify the effectiveness of the procedure. In Chapter 6, the author models the impedance impact of potting material and cooling cases on both CM and DM inductors. Experimental results match well with the developed models. In Chapter 7, a comprehensive design procedure for high density EMI filter in high power motor drives has been proposed, based on the knowledge of previous chapters. As the verification of the procedure, a high density EMI filter is designed and tested in a 100 kW three-phase motor drive system for MEA application. Conclusion and future work are summarized in Chapter 8

Common mode noise modelling and resonant estimation in a three-phase motor drive system: 9-150 kHz frequency range

This paper presents an equivalent circuit impedance-based estimation method of resonances in a three-phase motor drive system to predict common-mode (CM) noise circulations in 9-150 kHz frequency range, which is not considered so far in electromagnetic interference (EMI) analysis. The paper verifies the presented method by analyzing emission spectrums of CM currents in the three-phase system. The impact of EMI filter, DC-link filter and AC motor models on the generated common mode noise at 9-150 kHz range is also investigated using the predicted equivalent impedance results at the CM voltage source. It is found, there is a high probability to have resonances within 9-150 kHz range due to the components of the drive system. Hence, the work presented is useful to model and predict the possible resonances in the whole drive system that unnecessarily increases the CM noise at this frequency range. The presented estimation method not only enables the ability to early recognition of CM current emissions injected from the drive system to the grid but also supports EMI filter design or modification for 9-150 kHz frequency range. Further, this approach significantly contributes to accelerating the drive products development and entering the market after complying the future standards.</p

REDUCTION OF SUSCEPTIBILITY FROM ELECTROMAGNETIC INTERFERENCE IN SENSORLESS FOC OF IPMSM

This paper presents main problems of practical implementation of Field Oriented Control (FOC) developed for an Interior Permanent Magnet Synchronous Motor (IPMSM). The main sources of Electromagnetic Interferences (EMI) noises are discussed and practical aspects when a position sensor is used are presented. The control system is based on the DSP processing unit, together with inverter and encoder. The main problem addressed in this paper is reduction of vibrations in torque and speed response in a real system by re-placing a hardware device of control system very susceptible to EMI noises, like encoder, with a soft block in control unit like Sliding Mode Observer, less sensitive to EMI. The experimental results with this control structure show considerable ripple reduction at steady state in torque, speed and current, as a consequence of reduction of sensitivity to EMI noises

Mitigation Emission Strategy Based on Resonances from a Power Inverter System in Electric Vehicles

Large dv/dt and di/dt outputs of power devices in the DC-fed motor power inverter can generate conducted and/or radiated emissions through parasitics that interfere with low voltage electric systems in electric vehicles (EVs) and nearby vehicles. The electromagnetic interference (EMI) filters, ferrite chokes, and shielding added in the product process based on the black box approach can reduce the emission levels in a specific frequency range. However, these countermeasures may also introduce an unexpected increase in EMI noises in other frequency ranges due to added capacitances and inductances in filters resonating with elements of the power inverter, and even increase the weight and dimension of the power inverter system in EVs with limited space. In order to predict the interaction between the mitigation techniques and power inverter geometry, an accurate model of the system is needed. A power inverter system was modeled based on series of two-port network measurements to study the impact of EMI generated by power devices on radiated emission of AC cables. Parallel resonances within the circuit can cause peaks in the S21 (transmission coefficient between the phase-node-to-chassis voltage and the center-conductor-to-shield voltage of the AC cable connecting to the motor) and Z11 (input impedance at Port 1 between the Insulated gate bipolar transistor (IGBT) phase node and chassis) at those resonance frequencies and result in enlarged noise voltage peaks at Port 1. The magnitude of S21 between two ports was reduced to decrease the amount of energy coupled from the noise source between the phase node and chassis to the end of the AC cable by lowering the corresponding quality factor. The equivalent circuits were built by analyzing current-following paths at three critical resonance frequencies. Interference voltage peaks can be suppressed by mitigating the resonances. The capacitances and inductances generating the parallel resonances and responsible elements were determined by the calculation through the equivalent circuits. A combination of mitigation strategies including adding common-mode (CM) ferrite chokes through the Y-caps and the AC bus bar was designed to mitigate the resonances at 6 MHz, 11 MHz, and 26 MHz related to the CM conducted emission by IGBT switching and the radiated emission of the AC cable. The values of Z11 decreased respectively by 15 dB at 6 MHz, 0.4 dB at 11 MHz, and 11.5 dB at 26 MHz and the values of S21 decreased respectively by 8.6 dB at 6 MHz, 7 dB at 11 MHz, and 6.3 dB at 26 MHz. An equivalent model of the power inverter system for real-time simulation in time domain was built to validate the mitigation strategy in simulation software PSPICE

Design for Motor Controller in Hybrid Electric Vehicle Based on Vector Frequency Conversion Technology

Motor and its control technology are one of the main components of Hybrid Electric Vehicle (HEV). To meet HEV's fast torque response, vector control algorithm based on rotor flux-oriented and simulation model is concerned and modular designs for controller's hardware and software are presented in the paper in order to build a platform to achieve the vector control of asynchronous induction motor. Analyze the controller's electromagnetic compatibility, introduce the corresponding antijamming measures to assure the normal operation of the electromagnetic sensitive devices such as CAN bus; experiment proves that the measure is practical and feasible. On the basis of the control logic correct, such as improving CAN bus communication reliability, assuring power-on sequence and fault treatment, carry on the motor bench experiment, test its static properties, and adjust the controller parameters. The experimental results show that the designed driving system has the performance of low speed and high torque, a wide range of variable speed and high comprehensive efficiency

Common-Mode Current Prediction and Analysis in Motor Drive Systems for the New Frequency Range of 2–150 kHz

Due to the significant advances in fast switching semiconductor devices, harmonic emissions caused by the adjustable speed drives (ASDs) have been changed in terms of frequency range and magnitude. The frequency range of 2-150 kHz has been distinguished as a new interfering frequency range, disturbing the distribution networks. This article proposes a behavioral model of an ac motor to predict the common-mode (CM) current in ASDs. An approach is presented to calculate the parameters of the model, through which the dominant impact of each element at a specific frequency is considered. Moreover, along with the proposed motor model, a system modeling strategy is presented for filter design considerations at an emerging frequency range of 2-150 kHz. To verify the effectiveness of the proposed model, real-time experiments are conducted. The results prove that the introduced model can accurately predict the resonances of the CM loop created by the motor. Consequently, the proposed model is suitable for electromagnetic interference (EMI) filter design covering the 2-150-kHz standard. </p

Research and analysis of electromagnetic interference of a motor drive control system based on PMSM with SiC MOSFET for new energy electric vehicles

Sustainable development in the 21st century faces significant challenges due to finite reserves of fossil fuels and environmental pollution. In the context of new energy electric vehicles (NEEVs), the wide-bandgap semiconductor known as the silicon carbide–metal oxide–semiconductor field-effect transistor (SiC MOSFET) and the permanent magnet synchronous motor (PMSM) have emerged as advantageous sources. However, the use of these components gives rise to electromagnetic interference (EMI) issues, which impede the achievement of electromagnetic compatibility (EMC) standards in the motor drive control system. This paper aims to elucidate the generation mechanism, propagation path, and test infrastructure of EMI. Furthermore, it proposes a system-level conducted EMI equivalent circuit model for the motor drive control system, encompassing the power battery pack, busbar cable, LISN, three-phase inverter, and PMSM. Building upon this foundation, the principles for suppressing and optimizing EMI noise are discussed. The paper concludes with the validation of simulations and experimental results, which demonstrate the effectiveness of the proposed approach. It is anticipated that professionals with an interest in the field of EMI/EMC will find this paper to be of both theoretical and practical importance