Table of Content

03 November 2021, Volume 42 Issue 10

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Contents

Contents

2021, 42(10):  0. 

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Paper

Review on the Key Technologies and Development of All-electric Land Warfare Platform

LI Jiaqi， WEI Shuguang， LIAO Zili， ZANG Kemao

2021, 42(10):  2049-2059.  doi:10.3969/j.issn.1000-1093.2021.10.001

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The basic characteristics and key technologies of an all-electric land warfare platform are introduced， and the importance of the all-electric technologies for improving the performance of land warfare platform is elaborated in terms of vehicular mobility，sustainability，and combat capability. The development tendency of light-weight, intelligent and unmanned land warfare platform is further analyzed. The key technologies of all-electric land warfare platform are investigated in terms of drive motor and its control，integrated power system，electromagnetic weapon，and electromagnetic armor. The technical background and current bottlenecks are studied，and the developing direction of land warfare platform，which includes motor，power system，electromagnetism，are put forward. Finally，the potential future applications of all-electric technologies are explored.

State-of-the-art Technology and Prospects of Permanent Magnet In-wheel Motors for Electric Drive Vehicles

CHAI Feng, YU Yanlei, PEI Yulong

2021, 42(10):  2060-2074.  doi:10.3969/j.issn.1000-1093.2021.10.002

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Hybrid electric drive is an important research field of vehicle technology and is the basis for the full-electric high-mobility multipurpose ground vehicles，while the in-wheel drive system is the power core of the in-wheel drive vehicles，of which the performance of the in-wheel motor is particularly critical. The state-of-the-art technology and development trend of in-wheel motor is overviewed. The prospects for the development of existing novel permanent magnet motors in the field of in-wheel drive are outlined based on the requirements of high torque and wide speed range of in-wheel motors for electric drive vehicles. The key technical issues of permanent magnet in-wheel motors are summarized. The future developments are foreseen. A comprehensive review is made on the theoretical researches and practical applications of in-wheel motor drive system at home and abroad，with a view to providing a reference for the development of future motors used in electric drive vehicles.

Coordinated Control Strategy of Generator Sets of Series Hybrid Electric Vehicles

MA Xiaojun， XU Haoxuan， LIU Chunguang

2021, 42(10):  2075-2081.  doi:10.3969/j.issn.1000-1093.2021.10.003

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In the process of high-power loading，the flameout of series hybrid electric vehicle may be due to engine overload. In order to realize the smooth adjustment of engine-generator set，the reasons for the instability of engine-generator set during the adjustment process are analyzed，and a coordinated control strategy of engine-generator set is proposed，and the coordination method of engine-generator set is optimized. The energy loss of the on-board integrated power system during the dynamic adjustment of engine-generator set is reduced，and the power quality of bus in on-board integrated power system is improved. The hardware-in-the-loop simulation test shows that，compared with the traditional control strategy，the proposed strategy can achieve the minimum energy loss during the dynamic adjustment process，smooth the DC bus voltage fluctuation，and assist the engine-generator set to better implement the vehicle energy management strategy.

Double Channel Compensation Control of Bus Voltage for Armored Vehicle with Electric Transmission

LIAO Zili， SHU Xin， GAO Qiang， LI Jiaqi

2021, 42(10):  2082-2091.  doi:10.3969/j.issn.1000-1093.2021.10.004

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A bus voltage control strategy of armored vehicle with electric transmission is proposed for the fluctuating voltage arising in the process of sudden acceleration and deacceleration. A small signal model including the super capacitor and motor loads is developed based on the topological structure of vehicular integrated power system of 8×8 armored vehicle. The causes of two kinds of bus voltage fluctuations are analyzed. A dual-channel compensation control strategy is proposed based on power feedforward control strategy and the negative impedance characteristics of motor loads. The effect of the control strategy is evaluated by hardware-in-loop simulation and prototype vehicle test. The results show that the bus voltage fluctuations caused by sudden acceleration and deceleration are well restrained by using power feedforward control strategy, but it has no influence on the voltage fluctuation caused by negative impedance characteristics. The bus voltage fluctuations are effectively restrained by the dual-channel compensation control strategy, which also improves the anti-interference ability of the system.

Steering Control of Electric Drive Tracked Vehicle Considering Tracks' Skid and Slip

GAI Jiangtao， LIU Chunsheng， MA Changjun， SHEN Hongji

2021, 42(10):  2092-2101.  doi:10.3969/j.issn.1000-1093.2021.10.005

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The steering control strategy of electric drive vehicle considering tracks' skid and slip is researched to eliminate the influence of track' skid and slip on kinematics control of electric drive tracked vehicle in steering process and realize the accurate control of vehicle steering trajectory. The correction factors of steering radius and steering angular velocity, which characterize the slip characteristics of tracked vehicle in steering process, are analyzed. Based on the analyzed results, a steering control strategy considering the tracks' skid and slip is proposed, in which the correction factors of steering radius and the steering angular velocity are used to modify the revolution control command of drive motor speed. The comparative simulations and experiments of the steering control strategy without and with considering the tracks' skid and slip were carried out. The results show that the steering control strategy with considering the tracks' skid and slip can accurately achieve the steering control objectives, which verifies the feasibility of the proposed steering control strategy.

High-speed Obstacle Avoidance and Stability Control of Distributed Electric Drive Vehicle under Extreme Off-road Conditions

LIU Cong， LIU Hui, HAN Lijin, CHEN Ke

2021, 42(10):  2102-2113.  doi:10.3969/j.issn.1000-1093.2021.10.006

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A layered coordinated lateral stability control method is proposed to improve the high-speed obstacle avoidance ability and handling stability of distributed electric drive vehicles in extreme off-road environment, in which the attitude feedback of vehicle during cornering is fully considered. The upper controller combines the multi-model online modeling algorithm with the nonlinear model predictive control theory, and a coordinated control strategy for yaw and roll motion based on data-driven multi-model predictive control is proposed. Considering that the optimal control center is time-varying under different lateral instability states of vehicle, a two-level integrated yaw dynamic model is refined and reconstructed.Considering the time-varying road curvature and lateral slope angle under off-road conditions, a zero-moment point-based rollover instability judgment model is constructed, and the rollover stability control constraint is introduced on the basis of yaw stability control. The lower level controller converts the fused yaw moment into each wheel drive torque based on the quadratic programming algorithm. The joint simulation of MATLAB/Simulink and Carsim was built for test verification. The results show that the proposed layered coordinated control method can give full play to the high maneuverability of distributed electric drive vehicles under extreme off-road condition, which has a strong body attitude correction ability, and can improve the path tracking accuracy and the lateral stability of vehicle during cornering.

Standstill Parameter Identification of Permanent Magnet Synchronous Motor and Parameter Auto-tuning Method of Current LoopController

MENG Liu, ZHANG Huixuan, FAN Tao

2021, 42(10):  2114-2122.  doi:10.3969/j.issn.1000-1093.2021.10.007

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In the digital control system of permanent magnet synchronous motor (PMSM)，the parameter setting of current loop controller is an important factor affecting the current loop width and system control performance. An auto-tuning method based on standstill parameter identification is proposed to optimize the design process of control parameters，so that the control system is suitable for different motor platforms. In a standstill condition of PMSM，the stator resistance is identified by two-point voltammetry to eliminate the influence of dead band on stator resistance identification in pulse width modulation，the stator windings are excited by high frequency injection method，and the inductance values of quadrature and direct axis are obtained by using discrete Fourier transform. The method of parameter auto-tuning of current loop controller is analyzed and derived，and a current loop controller is designed according to the identified motor parameters. The proposed method was tested on two PMSM experiment platforms. The experimental results show that the proposed control method can make the PMSM have good dynamic and static performance.The validity of the method for standstill parameter identification of PMSM and parameter auto-tuning of current loop controller is proven through experiment.

Predictive Direct Power Control Strategy for Electric Drive System of Special Vehicle

HUANG Qing, NI Dacheng， MA Changjun, LUO Derong, HUANG Shoudao, LI Zhongqi, CHENG Wangyang, YAO Chao, DENG Haijun, DONG Ping, LU Xiongjian

2021, 42(10):  2123-2129.  doi:10.3969/j.issn.1000-1093.2021.10.008

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A predictive direct power control strategy is proposed for large current harmonics and power fluctuation of pulse width modulation (PWM) rectifier in electric drive system of special vehicle, and a current observer is designed based on the traditional control strategy. The disturbance caused by system parameter mismatch is estimated by the predictive control method and compensated in real time, and then the predicted current value at the next time is calculated by current prediction. A dynamic model for three-phase PWM rectifier is established. The current value after change in inductance can be predicted by the designed current observer and compared with the actual current value. Finally, the system error is compensated by estimating the system disturbance. Simulated results show that the proposed predictive direct power control strategy can be used effectively to suppress the current harmonic component and power pulsation, realize the normal operation under the condition of inductance parameter change, and better improve the quality of special vehicle power supply，and is available for the special vehicle electric drive system.

Prediction of Demand Power of Electric Drive Armored Vehicle Based on Improved Grey Markov Chain

LIU Chunguang， CHEN Luming， ZHANG Yunyin， ZHANG Zheng， XU Haoxuan

2021, 42(10):  2130-2144.  doi:10.3969/j.issn.1000-1093.2021.10.009

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A combined power prediction method based on improved grey Markov chain is proposed to solve the problem of low accuracy of demand power prediction for electric drive armored vehicles. The improved grey prediction method and Markov chain prediction method are used to predict the main power and residual power in the load demand power. The predicted results of demand and residual powers at each prediction moment are algebraically added to establish an improved grey Markov chain combination prediction method. The simulated results show that，compared with the traditional prediction method，the proposed demand power combination prediction method can better predict the strong randomness of load power and accurately predict the variation trend of demand power，and the prediction accuracy is increased by 16.49%，which can provide effective reference information for the energy management strategy.

Dynamics Response and Influence Factors of Electromechanical Transmission System Based on Lumped-distributed ParameterModel

WANG Zhen， XIANG Changle， LIU Hui， ZHANG Wei， XIE Yunkun

2021, 42(10):  2145-2158.  doi:10.3969/j.issn.1000-1093.2021.10.010

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Electromechanical transmission systems are widely used in new energy vehicles，high-speed trains and other fields. With the development of electromechanical transmission system in high speed，heavy load and light weight，its dynamics characteristics become more and more complex. The dynamics response and influence factors of a fixed shaft gear transmission system driven by a motor under both the action of bending-torsion-pendulum coupling excitation and nonlinear meshing excitation of involute spur gears are analyzed based on lumped-distributed parameter model.A concentration-distributed parameter dynamics model is established by combining the finite element method and the lumped parameter method. The generalized -a numerical method is used to solve the dynamics responses of the system， and the influences of the vibration of shaft and the eccentricity of gear on the dynamics responses of the system are analyzed in detail. It is found that the large von Mises alternating stresses at two points of both the gear installation position on the shaft and the connection position between shaft and bearing are predicted by using the lumped-distributed parameter model. In addition，it is found that the deformation of shaft can induce the new frequencies，such as the bending vibration frequency along Y and Z directions of shaft and the combined frequency of both the mesh frequency and the bending vibration frequency. The simulated results show that the bending vibration frequencies along Y and Z directions of shaft are 1 125 Hz and 874 Hz，respectively，and the magnitude and amplitude of the two frequencies are only determined by the natural characteristics of shaft. The influence laws of gear eccentricity on the system are as follows: with the increase in gear eccentricity，the time-varying dynamic mesh force，backlash，von Mises alternating stress and gear center vortex trajectory increase significantly，the maximum dynamic mesh force increases linearly with the gear eccentricity，and the increment ratio is 1.77×10⁹.

Energy Management of Hybrid Tracked Vehicle Based on Reinforcement Learning with Normalized Advantage Function

ZOU Yuan, ZHANG Bin, ZHANG Xudong, ZHAO Zhiying, KANG Tieyu, GUO Yufeng, WU Zhe

2021, 42(10):  2159-2169.  doi:10.3969/j.issn.1000-1093.2021.10.011

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The energy management strategy based on reinforcement learning encounters the problem of “dimension disaster”when dealing with high-dimensional problems because of the discretization of state and control variables. For this problem, a new energy management algorithm based on deep reinforcement learning with normalized advantage function is proposed, where two deep neural networks with normalized advantage function are used to realize the continuous control of energy and eliminate the discretization of state and control variables. Based on the modeling of powertrain of a series hybrid tracked vehicle, the framework of the proposed deep reinforcement learning algorithm was built and the parameter update process was completed for the series hybrid tracked vehicle. The simulated results show that the proposed algorithm can output more refined control quantity and less output fluctuation. Compared with the deep Q-learning algorithm, the proposed algorithm improves the fuel economy of series hybrid tracked vehicle by 3.96%. In addition, the adaptability of the proposed algorithm and the optimized effect in real-time control environment are verified by the hardware-in-the-loop simulation.

On Thermal Property of Reduction Gear for Electrical Transmission System of Tracked Vehicle

MA Tian， WANG Zhitao, ZHANG Xin， PANG Daqian， GAO Xiaoyu

2021, 42(10):  2170-2179.  doi:10.3969/j.issn.1000-1093.2021.10.012

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For improving the running stability of tracked vehicles，the thermal property of reduction gear for electrical transmission system of tracked vehicle is studied by 1D and 3D methods. 1D software is used to calculate the outlet pressure and flow rate of each lubrication and cooling orifice of reduction gear as well as the power loss and heat transfer path of reduction gear. The lubrication flow field and temperature field are simulated to obtain the temperature distribution of reduction gear by using 3D software.The research process of thermal properties of mechanical components in electric drive system of tracked vehicle is explored. The research process shows the advantages of 1D/3D software combined simulation method for the analysis of gear thermal property. It improves the accuracy of simulation results and shortens the simulation time.

Power Balance Control Strategy of Series Hybrid Tracked Vehicle under Rapid Acceleration

GAI Jiangtao， SHENG Hui， ZHOU Guangming， LIU Lifang

2021, 42(10):  2180-2188.  doi:10.3969/j.issn.1000-1093.2021.10.013

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The power balance of front and rear power chains of series hybrid tracked vehicle has a great influence on the dynamic performance of the vehicle. For the problem that the DC bus voltage of the system is pulled down to affect the dynamic performance of the vehicle during rapid acceleration，the power balance control strategy of series hybrid tracked vehicle under the condition of rapid acceleration is studied. Based on the system fluctuation under different driving motor external characteristics，and the vehicle driving power demand and engine-generator response characteristics，a power balance control strategy for that engine-generator makes the voltage stable and DC/DC-battery provides the power compensation is proposed and verified by simulation. The results show that the strategy can balance the powers of the front and rear power chainsduring rapid acceleration，and the DC bus voltage fluctuation range is -4.6%-2.36%，which can maintain the system stability well.

Steering on Ramp Control Strategy of Double Motor Coupling Drive Transmission for Tracked Vehicle

ZENG Gen， WANG Weida， GAI Jiangtao， MA Changjun， LI Xunming， LI Huanhuan

2021, 42(10):  2189-2195.  doi:10.3969/j.issn.1000-1093.2021.10.014

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The steering on ramp is a typical driving condition for tracked vehicle，and the control of steering on ramp is difficult because the dynamics on the ramp are quite different from those on the plane due to the influence of gravity forces along the ramp. In order to ensure a stable steering on ramp，the steering principle of the double motor coupling drive transmission is analyzed，and the dynamics and kinematics of tracked vehicle are studied. A kinematics and dynamics model of steering on ramp is proposed, and a model predictive control strategy is proposed based on the the proposed model. The control strategy is modeled by the MATLAB/Simulink for different slope angles and steering radii，and is verified using a tracked vehicle with double motor coupling drive transmission.The results show that the steering on ramp model has high creditability，and the steering on ramp control strategy based on model prediction can be used to make the vehicle steer stably.

Direct Yaw Moment and Torque Vector Control for Stability of 8×8 Distributed Electric Drive Armored Vehicles

CAI Lichun， LIAO Zili， LI Jiaqi， ZHANG Yunyin， WANG Keyu

2021, 42(10):  2196-2205.  doi:10.3969/j.issn.1000-1093.2021.10.015

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A direct yaw and torque vector control method for 8×8 distributed electric drive armored vehicles is proposed to improve the vehicle's driving stability and take advantage of the hub motor drive.A linear 2-DOF model of vehicle is established to calculate the desired yaw rate and the sideslip angle.A hierarchical controller is designed based on this model. The upper controller is to coordinate the yaw rate and the sideslip angle. The control outputs of the two variables are calculated by using sliding mode control，and the weight function is designed to obtain the yaw torque output. The lower controller divides the eight wheels into four groups according to the axis. Then the torque of each wheel can be obtained according to the yaw moment and longitudinal force by the torque vector synthesis. The real-time simulated results show that the proposed control method can distribute the wheel torque reasonably，control the yaw rate effectively，and improve the vehicle's driving stability.

Electromagnetic Optimization Design of Coaxial Magnetic Field Modulated Magnetic Gears

CHEN Yongdan， TIAN Zhen， SHEN Hongji， LIU Lifang

2021, 42(10):  2206-2214.  doi:10.3969/j.issn.1000-1093.2021.10.016

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With the increasing demand for transmission efficiency and reliability of special vehicles in the future，electric transmission will become an important development direction of the future transmission，and the electromagnetic optimization design of magnetic gears is one of the key technologies in the research and development of new electric transmission in the future. The transmission principle of coaxial magnetic field modulated magnetic gear is analyzed，the analytical equation of magnetic gears is established，and an electromagnetic optimization design method of magnetic gear based on Taguchi method and multi-target robust optimization algorithm is proposed. The speed and torque characteristics of magnetic gears prototype were tested in typical operating conditions. The results show that the transmission ratio is stabilized at 6.67，the output torque is 359.7 N·m，the output power is 56.49 kW，and the efficiency is 98.1%. The torque performance and efficiency achieve the optimization design targets.The electromagnetic optimization design method was verified through experiment.

Acquisition Method for Equivalent Thermal Conductivity Coefficient of Stator Winding of Permanent Magnet Motor

LI Ye, LI Qi, FAN Tao, WEN Xuhui, ZHAO Yihui

2021, 42(10):  2215-2222.  doi:10.3969/j.issn.1000-1093.2021.10.017

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Permanent magnet motor is widely used in various electric drive applications because of its high power density. The temperature rise of motor winding is an important factor to determine the rated power of motor. In the thermal analysis model of motor，it is the most difficult to determine the equivalent physical properties of winding model.A fitting method of equivalent thermophysical properties of winding based on motor test is proposed and compared with the measurement method of equivalent winding sample and the simulation method of complete winding wire model. Through the test verification，the winding sample is limited by the test conditions and its application scope is limited.The temperature rise of the whole wire model is small because the filling efficiency of impregnating varnish is not considered，but it can be used in the design stage. The fitting method of equivalent thermophysical properties of winding has high accuracy.Through verification，the proposed thermal evaluation method can accurately and quickly evaluate the thermophysical properties of motor winding，and a solution is proposed to determine the equivalent thermal conductivity of the simplified winding model.

Combination Principles of Pole-pair Numbers for Coaxial Magnetic Gear

HE Mingjie， PENG Jun， LUO Yinglu， LI Weiye

2021, 42(10):  2223-2232.  doi:10.3969/j.issn.1000-1093.2021.10.018

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The combination principles of pole-pair numbers of inner rotor，outer rotor and modulation teeth for the coaxial magnetic gear are studied. The topology of coaxial magnetic gear is introduced and the air-gap flux densities are investigated theoretically. The possible combinations of the pole-pair numbers of inner rotor，outer rotor and modulation tooth are studied based on the analysis of air-gap flux density harmonics. Four magnetic gears with different combinations of pole-pair number are designed and comprehensively compared based on finite element algorithm.A magnetic gear with 5 inner-rotor pole pairs，19 outer-rotor pole pairs and 24 modulated teeth was manufactured and tested.Both the theoretical analysis and test results demonstrate that the magnet gear could enjoy strong torque transmission capability and high gear ratio when the number of modulated teeth is the sum of pole pair numbers of inner and outer rotors.

The Scheme of Lightweight Integrated Mixing Transmission Based on Flat Motor for Tracked Vehicle

ZOU Tiangang， YAN Qingdong， GAI Jiangtao， HOU Wei， WANG Zhitao， SHUAI Zhibin， SUN Xueyan

2021, 42(10):  2233-2241.  doi:10.3969/j.issn.1000-1093.2021.10.019

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According to the requirements of tracked vehicles for high power supply capacity，high volume power density，high mobility，multi-function，light weight，etc.，a lightweight integrated mixing transmission based on flat motor is proposed by using the multi-objective comprehensive evaluation method to optimize a variety of transmission types，such as integrated hydro mechanical transmission，composite electro-mechanical transmission，pure electric drive，comprehensive heavy hybrid drive and light comprehensive hybrid drive. In the proposed scheme，the development trend and technical maturity of integrated hydro mechanical transmission and electric drive technology are considered.The proposed scheme can effectively tackle the problem of insufficient power supply capacity of integrated hydro mechanical transmission，improve the volume power density，enhance the mobility， expand the function of vehicle power cabin，and effectively control the weight.For the proposed scheme，the parameters were matched，and the maneuverability was predicted. The results show that the proposed scheme can effectively solve the layout and installation of vehicle power cabin，and avoid other problems caused by the long direction of vehicle compared to the original scheme， and the structure is reasonable and feasible.

The Joint Optimal Control Strategy of Multi-gear Parallel Hybrid Power System of Heavy-duty Vehicle

WANG Weiqi， WANG Weida， SUN Xiaoxia， ZHANG Yuanbo， LIU Cheng， XIANG Changle

2021, 42(10):  2242-2250.  doi:10.3969/j.issn.1000-1093.2021.10.020

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In the multi-gear parallel hybrid power system of heavy-duty vehicle，the motor power is coupled with the mechanical power inside the transmission，and both the engine and the motor have multiple independent gears.The relationship among electromechanical energy and power distribution and gear is complicated，so it is difficult to determine and optimize the power distribution and gear selection.To coordinate the power distribution and gear selection of multi-gear parallel hybrid power system，an energy management strategy is proposed for joint optimization of power and gear，a system comprehensive efficiency model under different working modes is established，the economy energy management goals are defined，the cost function to evaluate the shift cost of hybrid system is defined，and an joint optimization control strategy is designed for the system's comprehensive efficiency and shifting cost.The adaptive simulated annealing algorithm is used for solving optimal torque distribution proportion and shift gear.The simulated results show that the joint optimal control strategy can be used to solve the problem of coupling distribution of torque and gear of the system，and reduce the fuel consumption by 4.8% compared to the rule strategy using the economy shift law and by 14.7% compared to the rule strategy using the initial shift law，which can greatly improve the economy of the hybrid power system.

Torque Ripple Suppress Method of Double-layer Interior Permanent Magnet Synchronous Machines for Electric Vehicle

SUN Chengxu, LI Qi, FAN Tao, WEN Xuhui, LI Ye, WANG Yanyan, TAN Ping

2021, 42(10):  2251-2259.  doi:10.3969/j.issn.1000-1093.2021.10.021

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There is still a mount of torque ripples after conventional rotor step-skewing. For this problem, a method to suppress torque ripple based on torque waveform symmetry optimization and double-segment rotor step-skewing is proposed. A magnetic circuit analytical model is established to analyze the torque harmonics of a double-layer interior permanent magnet motor systematically. The main characteristic order of torque harmonics causing the torque ripple is revealed. The accuracy of the analytical model is verified by magnetic finite element analysis. The rotor magnetic pole is optimized by the analytical model to suppress the specific subharmonic of torque and improve the symmetry of torque waveform in the condition of keeping the electromagnetic performance of motor unchanged. The double-segment rotor step-skewing is used to further weaken the torque harmonics which cause torque ripple. The simulated results show that the proposed method is used to reduce the torque ripple of benchmark motor effectively compared with the conventional rotor step-skewing.

Modeling and Vibration Characteristics of Electromechanical Coupling Dynamics of Wheel Hub Driving System forWheeled Armored Vehicle

LIU Yue， XI Junqiang， TIAN Zhen， ZHANG Xin

2021, 42(10):  2260-2267.  doi:10.3969/j.issn.1000-1093.2021.10.022

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A dynamic modeling and analysis method considering the coupling effect of drive motor and planetary transmission mechanism is proposed to obtain the electromechanical dynamic characteristics of wheel hub driving system. Based on the spatial electromagnetic force model of driving motor，the radial force，tangential force and torque ripple of the motor are calculated as the dynamic excitation of mechanical system of electric driving wheel. A dynamic model of planetary gear mechanism with flexible shell is established for the electromechanical coupling dynamic simulation of driving motor and planetary gear mechanism.The result shows that the low-order modal of the wheel hub driving system is mainly the global modal， and the high-order modal is mainly the local modal of the planetary transmission system. For the vibration response of the system，the high-order electromagnetic excitation is the main cause in the low speed region，while the low-order electromagnetic excitation is the main cause in the high speed region.

Transient Temperature Field of Planetary Gear System in Electro-mechanical Transmission under Different Working Conditions

PANG Daqian， ZENG Gen， LI Xunming， GUO Lei， ZHAO Fuqiang， SUN Zhanchun

2021, 42(10):  2268-2277.  doi:10.3969/j.issn.1000-1093.2021.10.023

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The transient meshing temperature of planetary gear system rises sharply when the electro-mechanical composite transmission device works in a harsh environment such as high speed, heavy load and high oil temperature. The transient temperature fields of planetary gear system model under different speeds, different loads, variable speed and constant power are calculated by finite element method. The transient temperature curves and tooth surface heating of sun gear and planetary gear under different conditions are analyzed, and the three-dimensional curves of transient temperature field on tooth top surface and tooth root surface under different working conditions are drawn. The relative growth relationship and growth amount of transient temperature on tooth surface are discussed in detail, and the influence laws of different rotating speed, different torques and output power on the transient temperature field of sun gear and planetary gear are obtained. Under different rotating speeds, the root surface temperature and maximum top surface temperature of sun gear and planetary gear teeth gradually increase with the increase in rotating speed, and when the rotating speed of sun gear is greater than 5 000 r/min, the increase rate of maximum temperature gradually decreases. Under the condition of constant power, the absolute value of the reduced maximum temperature of the top surface and root surface of sun gear and planetary gear teeth is basically equal to twice of the previous rotating speed point with the increase in rotating speed. The correctness of the method used in this paper is verified by experiments.

Acceleration Slip Regulation for Multi-wheel Hub Motor Driven Vehicles Based on Road Adaptive

CHEN Luming，LIAO Zili，ZHANG Zheng

2021, 42(10):  2278-2290.  doi:10.3969/j.issn.1000-1093.2021.10.024

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An acceleration slip regulation strategy with dynamic road identification is proposed to enhance the dynamic performance and steering stability of multi-wheel hub motor driven vehicles. The nonlinear three-degree-of-freedom vehicle model, wheel force model, and Dugoff tire model are established, respectively. Based on those models, a fading memory unscented Kalman filter is used to estimate the road adhesion coefficient. The traditional sliding mode control algorithm is improved, and a fuzzy sliding mode controller is designed to adaptively adjust the tire slip rate according to the road conditions and calculate the adjustment torque for acceleration slip regulation. A series of tests were conducted on the real-time simulation platform. The simulated results show that the driving force coordinated control strategy can be used to accurately identify the road adhesion coefficient, quickly adapt to the different road conditions, reduce the excessive tire slip, and improve the driving performance and handling stability performance of vehicle.