The need for more efficient and renewable means of transport makes the development of hybrid electric vehicles (HEVs) an important topic for both automobile manufacturers and academic researchers. Noise, vibration, and harshness (NVH) of a vehicle are important factors for vehicle users and essential for successful commercialization of this vehicle type. This paper is a compact state-of-the-art review of both NVH characteristics and relevant suppression methods for HEVs. The NVH-related problems are categorized into three categories: engine, powertrain, motor-related. A detailed overview of each category/problem-type is provided, the NVH-suppression methods for different types of HEVs are introduced, and their respective advantages discussed. In addition, emerging developments and ideas for future improvements are summarized. As a result, the paper should be particularly helpful for researchers, who are interested in the development of high-performance HEVs that can provide both substantially improved ride-comfort and reduced energy-consumption.

Noise and vibration suppression in hybrid electric vehicles: State of the art and challenges

An integral part of any modern day electric vehicle is power electronic circuits (PECs) comprising of DC-AC inverters and DC-DC converters. A DC-AC inverter supplies the high power electric motor and utility loads such as air-conditioning system, whereas a DC-DC converter supplies conventional low-power, low-voltage loads. However, the need for high power bidirectional DC- DC converters in future electric vehicles has led to the development of many new topologies of DC-DC converters. This paper presents an overview of state-of-the-art DC-DC converters used in battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and fuel cell vehicles (FCVs). Several DC-DC converters such as isolated, nonisolated, half-bridge, full-bridge, unidirectional and bidirectional topologies, and their applications in electric vehicles are presented.

DC-DC converters for electric vehicle applications

Linear switched reluctance motor (LSRM) drives are investigated and proved in this study as an alternative actuator for vertical linear transportation applications such as a linear elevator. A one-tenth-scaled prototype elevator that is focused on a home elevator with LSRMs is designed, and extensive experimental correlation is presented for the first time in this paper. The proposed LSRM has twin stators and a set of translator poles without yoke placed between the two stators. The features of the LSRM and the prototype elevator are described. Furthermore, a control strategy for the prototype elevator is introduced consisting of four control loops, viz., (1) current, (2) force, (3) velocity, and (4) position feedback control loops. Force control of the experimental prototype elevator employs the proposed force distribution function. A trapezoidal velocity profile is introduced to control vertical travel position smoothly during ascent, descent, and stop of the elevator. Conventional proportional-integral controller is used for the current and velocity control loops and their designs are described. The proposed control strategy is dynamically simulated and experimentally correlated. The analytical and experimental results of this paper prove that LSRMs are one of the strong candidates for linear elevator propulsion drives.

Design and Control of A Ropeless Elevator with Linear Switched Reluctance Motor Drive Actuation Systems

Interleaved multichannel power factor correction (PFC) converter is very popular today because of its ability to reduce input and output current ripples. In this paper, the common-mode (CM) electromagnetic interference noise emission model of the multichannel PFC converter is studied. A balance technique is introduced to reduce CM noise emission. To improve the high-frequency balance, a novel topology with coupled-inductor structure is proposed. Its CM noise model is derived and balance condition for minimizing CM noise is calculated. Effects of phase shift and channel shedding on this solution are also studied. The proposed topology has effectively reduced CM noise under any phase shift and channel shedding conditions. A two-channel PFC converter is built to verify the proposed balance technique. Experimental results show that CM noise can be reduced up to 20 dB between 150 kHz and 7 MHz.

Common-Mode EMI Study and Reduction Technique for the Interleaved Multichannel PFC Converter

Methods to control electromagnetic interference (EMI) noises, especially common mode currents and radiations that are generated in electric vehicle (EV) drive systems, were studied using an electric vehicle (EV) prototype. Fast fourier transform (FFT) analyses of the voltage and current appearing in the EV drive systems showed that electromagnetic interference (EMI) noise sources are produced by voltage fluctuations occurring at the time of switching operations and the produced noise sources cause common mode currents to flow into the ground when the body frame is connected to the ground. Moreover, the flowing common mode currents induce radiated EMI noises, while the generated EMI noises are transmitted between the inverter, batteries, and motors. Thus, the produced radiated EMI noises have an effect on nearby vehicles. A method was proposed that controls common mode currents produced in EV drive systems so as to prevent a series resonance phenomenon from occurring in common current paths formed in EV drive systems. This method is also effective in controlling radiated EMI noises. Furthermore, to control radiated EMI noises, another method was proposed that cancels the surface currents flowing in P and N power transmission lines between the inverter and batteries. Effectiveness of these proposed EMI noise control methods was verified from simulations and experiments.

EMI noise control methods suitable for electric vehicle drive systems

Electromagnetic interference (EMI) noises generated in power converters are diffused on the surface of conductors. This means influences occur from radiated EMI noises emitted from power transmission lines as well as conducted EMI noises transmitted from them. EMI noises diffusing on the surface of conductors are generally difficult to control using conventional concentrated constant theory. Thus, a new approach based on distributed constant circuit theory is needed in order to control EMI noises. A power converter structure to control EMI noises using multilayer power printed circuit technology is studied in this paper. A structure which can control EMI noises should simultaneously satisfy two conditions, i.e., one to shut down and one to attenuate EMI noises. The structure satisfying these conditions is studied through simulations using the Transmission-Line Modeling Method. The simulations show that the diffusion of EMI noises is controlled by dividing the flow of currents produced by EMI noises into the horizontal and perpendicular directions. That is, the horizontal current flow is controlled inside using the differences in the resistance produced from differences between inner and outer diameter of power transmission lines and the perpendicular current flow can be controlled by properly designing the thickness of the dielectric layer sandwiched between P-and N-power transmission lines with the symmetrical structure. Moreover, it is confirmed by simulations and experiments that the attenuation of EMI noises is affected by the width of the power transmission lines. It is expected that the results obtained in this paper can provide important rules when designing power converters with EMI noise control functions which use the multilayer power printed circuit technology.

Multilayer power printed structures suitable for controlling EMI noises generated in power converters

A control method is studied which provides countermeasures for common mode currents, micro-surges and shaft currents appearing in motor drive systems. Flow of common mode currents differs between motor drive systems because common mode current paths are varied by the installation of the systems. First, EMI noise sources producing common mode currents are analyzed using simulations. Experimental results are compared with analyzed results, and the cause and the paths of common mode currents are clarified. It is found that common mode currents occur due to multi-series resonance phenomena with multi-noise sources produced by voltage fluctuations due to switching operations and micro-surges appearing at terminals of the AC reactor and motor. Circuit parameters for common mode current paths must be researched in order to suppress multi-series resonance phenomena. A simple method is proposed which is characterized by field of adjustment circuit parameters to suitable values to prevent electrical shock by remote control via the web. Effectiveness of the proposed method is verified through simulations and experiments. Further, the common mode currents leaking into the ground as shaft currents are studied. As a result, a method is proposed that controls both the micro-surge occurring at motor terminals and the shaft current using multi-layer power printed circuit technique. In the method, the second layer structure is important because the layer has the function to bypass and damp micro-surges. A decision method for parameters of the circuit composed of the second layer is studied from the standpoint of bypassing and attenuating the micro-surge component through theoretical and experimental analyses. Finally, suppression effects of the proposed method on the macro-surge and the shaft current are verified through experiments. Moreover, it is found through experiments that the proposed method satisfactorily attenuates radiated EMI noise appearing on motors.

A new method to control common mode currents focusing on common mode current paths produced in motor drive systems

This paper describes control methods for EMI noises appearing in EV drive systems and radiations induced on the body frame of EVs by them. The methods are proposed through experimental and theoretical analyses of EMI noises appearing in the EV drive systems. The analyzed results show that there are two kinds of EMI noises in EV drive systems. One is differential mode noises appearing due to series resonance phenomena in the DC circuit between batteries and inverters at the time of switching operations. The produced noises are diffused into the body frame via stray capacitors between the inverter and car body frames as a common mode current. The other kind is EMI noises caused by surges appearing at motor terminals. They cause another common mode current that diffuses into the body frame via the motor shaft. The surface currents appearing on the body frame through these diffusion processes induce radiations around the body frame which cause electromagnetic interference between EVs. One method is proposed that controls differential mode noises including radiations induced by them; it uses a multilayer printed power circuit technique. Another method is proposed that prevents radiations induced by the common mode current produced due to surges occurring at motor terminals by suppressing series resonance phenomena occurring in common current paths. It was verified from simulations and experiments that these methods controlled EMI noises including radiations which appear in EVs

Control methods for EMI noises appearing in electric vehicle drive systems

The structure of power converters with a rectifier and an inverter is studied through simulations using the TLM (transmission-line modeling) method. The structure has the ability to prevent EMI noises from diffusing in noise sources. First, analyses regarding frequencies with EMI noises occurring by switching operations are performed using circuit parameters of an intelligent power module (IPM) composed of the power converters, which were previously measured, and then obtained results are verified by experiments. Processes in which the noise with the verified frequency diffuses into power transmission lines formed by power converters are analyzed by the EMI noise analyzing software (micro-strips) used the TLM method. On the basis of the analyzed results, structures of the power transmission lines suitable for attenuating EMI noises are proposed and these are applied to power converters formed using a multi-layer power printed board. One structure was chosen and compared with the conventional molded type one. The damping rate of the near magnetic fields was improved as much as 30 dB. Moreover, when the proposed power converter was equipped on electric vehicles (EVs), influence which the near-magnetic fields has on an approaching car was investigated in comparison with radiated EMI noises between electric vehicles (EVs) with the proposed and conventional power converters. As a result, it was proved through simulations that EVs with little electromagnetic interference would be realizable by applying the proposed structure.

https://ieeexplore.ieee.org/iel5/9011/28610/01280683.pdf

J. Nakashima

Papers

EMI noise control methods suitable for electric vehicle drive systems

Multilayer power printed structures suitable for controlling EMI noises generated in power converters

A new method to control common mode currents focusing on common mode current paths produced in motor drive systems

Control methods for EMI noises appearing in electric vehicle drive systems

A new method to control EMI noises generated in power converters