# The Structure Principle and Dynamic Characteristics of Mechanical-Electric-Hydraulic Dynamic Coupling Drive System and Its Application in Electric Vehicle

^{1}

^{2}

^{*}

## Abstract

**:**

## 1. Background and Significance

#### 1.1. Introduction

#### 1.2. Challenges of the MEH-DCDS

#### 1.3. Contribution of This Paper

- (1)
- In this paper, a new mechanical-electro-hydraulic dynamic coupling drive system (MEH-DCDS) is proposed, which consists of a permanent magnet synchronous motor and a swash plate plunger pump/motor. It can realize the mutual conversion between mechanical energy, hydraulic energy, and electrical energy.
- (2)
- The dynamic characteristics of MEH-DCDS are analyzed.
- (3)
- MEH-DCDS was applied to electric vehicles, and the feasibility of MEHPC-EV was verified by co-simulation.

#### 1.4. The Structure of the Paper

- (1)
- Section 2 illustrates the structure of MEH-DCDS.
- (2)
- Section 3 introduces the working principle of MEH-DCDS.
- (3)
- Section 4 completes the mathematical model of MEH-DCDS.
- (4)
- Section 5 analyzes the dynamic characteristics of MEH-DCDS.
- (5)
- Section 6 describes the application of MEH-DCDS in electric vehicles.
- (6)
- Section 7 realizes the simulation and analysis of MEHPC-EV.

## 2. The Structure of MEH-DCDS

#### 2.1. Supporting System

#### 2.2. Electric Energy Conversion System

#### 2.3. Mechanical Energy Conversion System

#### 2.4. Hydraulic Energy Conversion System

## 3. The Working Principle of MEH-DCDS

## 4. Mathematical Model of MEH-DCDS

#### 4.1. Hydraulic Power

_{p}is calculated as follows:

_{p}is the pressure difference between the high pressure accumulator and low pressure accumulator; V

_{p}is the displacement of hydraulic pump/motor; and η

_{p}is the mechanical efficiency of hydraulic pump/motor.

_{0}is the pre-charge pressure of the gas; v

_{0}is the accumulator charging volume; p

_{1}is the minimum working pressure of the accumulator; v

_{1}is the volume of gas before the accumulator works; p

_{2}is the maximum working pressure of the accumulator; and v

_{2}is the gas volume after the accumulator works.

_{gas}is the gas pressure; P

_{max}is the maximum pressure; V

_{gas}is the volume of gas; and V

_{0}is the volume of the accumulator.

_{out}is the output pressure of the accumulator.

#### 4.2. Electric Power

_{req}of the motor is confined by the limit torque T

_{lim}:

_{lim}is the minimum torque of the motor; and T

_{max}is the maximum torque of the motor.

_{m}is dictated by the limit torque T

_{lim}, which is calculated using first-order lag.

_{r}is the user-defined time constant.

_{mec}and power loss P

_{lost}of the motor are calculated as follows:

_{e}is the rotational speed of the motor shaft.

_{mec}and electrical power P

_{elec}is as follows:

_{elec}is the electric power; η

_{m}is the motor efficiency; and η

_{g}is the generator efficiency.

_{out}and SOC of the battery are calculated as follows:

_{oc}is the open-circuit voltage of the power battery; R is the internal resistance of the power battery; I is the current of the power battery; SOC is the state of charge of the power battery; SOC

_{0}is the initial state of charge of the power battery; and Q

_{0}is the capacity of the power battery.

## 5. The Dynamic Characteristics of MEH-DCDS

#### 5.1. Analysis of Pump in MEH-DCDS Hydraulic Module

#### 5.2. Analysis of Motor in the MEH-DCDS Hydraulic Module

## 6. Application of MEH-DCDS in Electric Vehicles

## 7. Simulation and Analysis of MEHPC-EV

#### 7.1. Whole Vehicle Simulation Model

#### 7.2. Results and Analysis

## 8. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

- Wang, Y.N. Power Battery Performance Detection System for Electric Vehicles. Procedia Comput. Sci.
**2019**, 154, 759–763. [Google Scholar] [CrossRef] - Gulhane, V.; Tarambale, M.R.; Nerkar, Y.P. A Scope for the Research and Development Activities on Electric Vehicle Technology in Pune City. In Proceedings of the 2006 IEEE Conference on Electric and Hybrid Vehicles, Pune, India, 18–20 December 2006; pp. 1–8. [Google Scholar]
- Emadi, A.; Lee, Y.J.; Rajashekara, K. Power Electronics and Motor Drives in Electric, Hybrid Electric, and Plug-In Hybrid Electric Vehicles. IEEE Trans. Ind. Electron.
**2008**, 55, 2237–2245. [Google Scholar] [CrossRef] - Rezaee, S.; Farjah, E.; Khorramdel, B. Probabilistic Analysis of Plug-In Electric Vehicles Impact on Electrical Grid Through Homes and Parking Lots. IEEE Trans. Sustain. Energy
**2013**, 4, 1024–1033. [Google Scholar] [CrossRef] - Zhang, Q.-Y.; Huang, J. Research on regenerative braking energy recovery system of electric vehicles. J. Interdiscip. Math.
**2018**, 21, 1321–1326. [Google Scholar] [CrossRef] - Sharifan, S.; Ebrahimi, S.; Oraee, A.; Oraee, H. Performance Comparison between Brushless PM and Induction Motors for Hybrid Electric Vehicle Applications. In Proceedings of the 2015 Intl Aegean Conference on Electrical Machines & Power Electronics (ACEMP), 2015 Intl Conference on Optimization of Electrical & Electronic Equipment (OPTIM) & 2015 Intl Symposium on Advanced Electromechanical Motion Systems (ELECTROMOTION), Side, Turkey, 2–4 September 2015; pp. 719–724. [Google Scholar]
- Wang, X.; Zhang, Z.; Gao, P.; Lu, H.; He, X. Design and Simulation Analysis of a Novel Outer Rotor IPM Motor Used in Electric Vehicles. In Proceedings of the 2018 13th World Congress on Intelligent Control and Automation (WCICA), Changsha, China, 4–8 July 2018; pp. 1413–1418. [Google Scholar]
- Park, J.-W.; Koo, D.-H.; Kim, J.-M.; Kim, H.-G. Improvement of control characteristics of interior permanent-magnet synchronous motor for electric vehicle. IEEE Trans. Ind. Appl.
**2001**, 37, 1754–1760. [Google Scholar] [CrossRef] - Loganayaki, A.; Kumar, R.B. Permanent Magnet Synchronous Motor for Electric Vehicle Applications. In Proceedings of the 2019 5th International Conference on Advanced Computing & Communication Systems (ICACCS), Coimbatore, India, 15–16 March 2019; pp. 1064–1069. [Google Scholar]
- Yang, Y.; He, Q.; Fu, C.; Liao, S.; Tan, P. Efficiency improvement of permanent magnet synchronous motor for electric vehicles. Energy
**2020**, 213, 118859. [Google Scholar] [CrossRef] - Ma, B.; Lin, M.; Chen, Y.; Wang, L. Investigation of energy efficiency for electro-hydraulic composite braking system which is based on the regenerated energy. Adv. Mech. Eng.
**2016**, 8, 168781401666644. [Google Scholar] [CrossRef] [Green Version] - Li, C.; He, C.; Yuan, Y.; Zhang, J. Braking Evaluation of Integrated Electronic Hydraulic Brake System Equipped in Electric Vehicle. In Proceedings of the 2019 IEEE 3rd Information Technology, Networking, Electronic and Automation Control Conference (ITNEC), Chengdu, China, 15–17 March 2019; pp. 2361–2365. [Google Scholar]
- Yang, N.A.; Luo, C.; Li, P. Design and performance analysis on a new electro-hydraulic hybrid transmission system. Int. J. Electr. Hybrid. Veh.
**2017**, 9, 134. [Google Scholar] [CrossRef] - Li, S.; He, X.; Wang, Q.; Shen, X.; Zhang, T. Research on the Acceleration Performance of a Wheel Drive Hydraulic Hybrid Vehicle Driven by Accumulators. IOP Conf. Ser. Mater. Sci. Eng.
**2019**, 563, 32028. [Google Scholar] [CrossRef] - Niu, G.; Shang, F.; Krishnamurthy, M.; Garcia, J.M. Design and Analysis of an Electric Hydraulic Hybrid Powertrain in Electric Vehicles. IEEE Trans. Transp. Electrif.
**2017**, 3, 48–57. [Google Scholar] [CrossRef] - Wang, T.; Wang, Q. Modeling and control of a novel hydraulic system with energy regeneration. In Proceedings of the 2012 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM), Kaohsiung, Taiwan, 11–14 July 2012; pp. 922–927. [Google Scholar]
- Chen, J.-S. Energy Efficiency Comparison between Hydraulic Hybrid and Hybrid Electric Vehicles. Energies
**2015**, 8, 4697–4723. [Google Scholar] [CrossRef] [Green Version] - Rezaei, A.; Burl, J.B.; Rezaei, M.; Zhou, B. Catch Energy Saving Opportunity in Charge-Depletion Mode, a Real-Time Controller for Plug-In Hybrid Electric Vehicles. IEEE Trans. Veh. Technol.
**2018**, 67, 11234–11237. [Google Scholar] [CrossRef] - Hong, J.; Wang, Z.; Chen, W.; Wang, L.; Lin, P.; Qu, C. Online Accurate State of Health Estimation for Battery Systems on Real-World Electric Vehicles with Variable Driving Conditions Considered. J. Clean. Prod.
**2021**, 294, 125814. [Google Scholar] [CrossRef] - Hong, J.; Wang, Z.; Ma, F.; Yang, J.; Xu, X.; Qu, C.; Zhang, J.; Shan, T.; Hou, Y.; Zhou, Y. Thermal Runaway Prognosis of Battery Systems Using the Modified Multiscale Entropy in Real-World Electric Vehicles. IEEE Trans. Transp. Electrification
**2021**, 7, 2269–2278. [Google Scholar] [CrossRef] - Zeraoulia, M.; Benbouzid, M.E.H.; Diallo, D. Electric Motor Drive Selection Issues for HEV Propulsion Systems: A Comparative Study. In Proceedings of the 2005 IEEE Vehicle Power and Propulsion Conference, Chicago, IL, USA, 7–9 September 2005; pp. 280–287. [Google Scholar]
- Song, J.; Jung, D.; Kim, S.; Lee, S.; Park, H.; Kim, D.; Park, S.; Kwon, S.; Kim, Y.; Hong, J. Power density improvement design of the traction motor for the hybrid electric vehicle. In Proceedings of the INTELEC 2009—31st International Telecommunications Energy Conference, Incheon, Korea, 18–22 October 2009; pp. 1–4. [Google Scholar]
- Kano, Y.; Inoue, Y.; Sanada, M. Current specifications of vehicle motors. In Proceedings of the 2013 IEEE ECCE Asia Downunder, Melbourne, Australia, 3–6 June 2013; pp. 136–140. [Google Scholar]
- Yang, R.; Schofield, N.; Zhao, N.; Emadi, A. Dual three-phase permanent magnet synchronous machine investigation for battery electric vehicle power-trains. J. Eng.
**2019**, 2019, 3981–3985. [Google Scholar] [CrossRef] - Meng, Z.; Zhang, T.; Zhang, H.; Zhao, Q.; Yang, J. Energy Management Strategy for an Electromechanical-Hydraulic Coupled Power Electric Vehicle Considering the Optimal Speed Threshold. Energies
**2021**, 14, 5300. [Google Scholar] [CrossRef] - Yang, J.; Zhang, T.; Zhang, H.; Hong, J.; Meng, Z. Research on the Starting Acceleration Characteristics of a New Mechanical–Electric–Hydraulic Power Coupling Electric Vehicle. Energies
**2020**, 13, 6279. [Google Scholar] [CrossRef] - Nadeau, J.; Micheau, P.; Boisvert, M. Collaborative control of a dual electro-hydraulic regenerative brake system for a rear-wheel-drive electric vehicle. Proc. Inst. Mech. Eng. Part J. Automob. Eng.
**2019**, 233, 1035–1046. [Google Scholar] [CrossRef] - Hong, J.; Wang, Z.; Yao, Y. Fault prognosis of battery system based on accurate voltage abnormity prognosis using long short-term memory neural networks. Appl. Energy
**2019**, 251, 113381. [Google Scholar] [CrossRef] - Kang, H.; Dandan, Z. Study on Driving Motor of Pure Electric Vehicles Based on Urban Road Conditions. In Proceedings of the 2013 International Conference on Communication Systems and Network Technologies, Gwalior, India, 6–8 April 2013; pp. 839–842. [Google Scholar]

**Figure 1.**Four major system structures of the mechanical-electric-hydraulic dynamic coupling drive system (MEH-DCDS).

**Figure 4.**Diagram of low pressure accumulator (LPA) pressure and single plunger flow rate at low pressure oil port on pump analysis.

**Figure 5.**Diagram of high pressure accumulator (HPA) pressure and single plunger flow rate at high pressure oil port on pump analysis.

**Figure 7.**Diagram of HPA pressure and single plunger flow rate at high pressure oil port on motor analysis.

**Figure 8.**Diagram of LPA pressure and single plunger flow rate at low pressure oil port on motor analysis.

**Figure 9.**Diagram of Mechanical-Electric-Hydraulic Power Coupling Electric Vehicle (MEHPC-EV) structure and energy flow.

**Figure 11.**Diagram of MEHPC-EV simulation analysis. (

**a**) is the speed curve, (

**b**) is the accumulator pressure curve, (

**c**) is the motor torque curve, and (

**d**) is the battery SOC consumption rate curve.

Components | Main Parameters | Value |
---|---|---|

Loaded mass (m) | 1206 kg | |

Frontal area (A) | 2.28 m^{2} | |

Main parameters of the car | Rolling resistance coefficient (f) | 0.0135 |

Coefficient of air resistance (C_{D}) | 0.32 | |

Wheel width (R) | 290 mm | |

Transmission efficiency (η) | 0.85 | |

High pressure accumulator | Work pressure (P_{1}) | 240–350 Bar |

Volume (V) | 35 L | |

Low pressure accumulator | Work pressure (P_{2}) | 60–220 Bar |

Volume (V) | 35 L | |

Secondary component | Displacement (V_{p}) | 30 mL·r^{−1} |

Motor | Rated power (P_{e}) | 32 KW |

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |

© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Sun, Y.; Zhang, H.; Yang, J.
The Structure Principle and Dynamic Characteristics of Mechanical-Electric-Hydraulic Dynamic Coupling Drive System and Its Application in Electric Vehicle. *Electronics* **2022**, *11*, 1601.
https://doi.org/10.3390/electronics11101601

**AMA Style**

Sun Y, Zhang H, Yang J.
The Structure Principle and Dynamic Characteristics of Mechanical-Electric-Hydraulic Dynamic Coupling Drive System and Its Application in Electric Vehicle. *Electronics*. 2022; 11(10):1601.
https://doi.org/10.3390/electronics11101601

**Chicago/Turabian Style**

Sun, Yue, Hongxin Zhang, and Jian Yang.
2022. "The Structure Principle and Dynamic Characteristics of Mechanical-Electric-Hydraulic Dynamic Coupling Drive System and Its Application in Electric Vehicle" *Electronics* 11, no. 10: 1601.
https://doi.org/10.3390/electronics11101601