This project belongs to the field of mechatronics technology, covering disciplines such as vehicle engineering, mechanical design and theory, electronic engineering, control theory and application, signal detection and processing, etc., and is in line with the national high-tech product catalog-high-performance automotive electronic devices and key automotive components. This project has developed China's first high-performance electric power steering system (EPS) driven by permanent magnet synchronous motors. Its key performances have reached the international advanced level. It is the first in China to pass the review by the international authoritative certification body TUV based on the international functional safety standard IEC61508. It has completely independent intellectual property rights. Even today, there is no second company in China that has independently developed high-performance EPS driven by high-power permanent magnet synchronous motors.
Through research on system matching, electronic control units, mechanical structure and industrialization, this project has made breakthroughs in matching design of high-power electric steering systems, high-power controller design and control strategies, EPS fault diagnosis, design and manufacturing technology of key mechanical parts, EPS testing capacity building, vehicle debugging and calibration technology of EPS systems, production capacity building of EPS systems and controllers, etc., forming a complete high-performance EPS development system, and achieving the following innovative results:
1)A high-performance electric power steering system (EPS) control strategy based on permanent magnet synchronous motors is established to solve problems such as nonlinear steering feel, large residual correction angle, and torque fluctuations at different vehicle speeds during EPS vehicle-speed assistance. The residual correction angle of this project is 8.5°, which is far better than the residual correction angle of 46° of Volkswagen POLO, which is loaded with similar products from the international steering system supplier NSK Japan.
2)The development of noise suppression technology based on permanent magnet synchronous motor control and worm wheel and worm clearance self-adjusting mechanism solves the noise problem caused by motor vibration and worm wheel wear during high-torque operation, and meets the low noise demand of new energy vehicles for steering systems. The system noise is 45.5 dB (A), which exceeds the noise level of NSK in Japan by 50.5 dB (A).
3)The proposed high-standard electromagnetic compatibility (EMC) high-current controller (ECU) design method solves the problem of radiated interference at high currents and high frequencies of the controller; the radio frequency radiated emission (RE) and conducted radiation (CE) based on the CISPR25 standard have reached the same level as Japan's NSK and Germany's ZF steering systems (Level 3), and some frequency bands are even better than NSK.
4)The established EPS functional safety design and verification specification that meets the IEC 61508 standard has passed the review of the international authoritative review organization TUV;
In addition to the above innovative achievements, this project has also achieved other results: establishing specifications for steering performance debugging and calibration of EPS vehicles; solving the riveting and online calibration process of torque sensors in the industrialization process; developing a high-power worm wheel manufacturing process; Formed an annual batch production capacity of 500,000 EPS units.
After review by industry experts, it is believed that the overall development technology and comprehensive product performance of this project are leading in China, and key indicators such as residual angle of correction, steering system noise, and radiated interference have reached the international advanced level.
This project has been highly praised by Mahindra, which believes that "this project is at the same level as EPS, a major international brand in the China market."
The successful development of this project broke through the technical blockade of high-performance electric steering systems by international steering system suppliers and laid the foundation for the development of smart vehicles.
This project has obtained a total of 3 authorized invention patents, accepted 5 invention patents, authorized 4 utility model patents, 4 software copyrights, and 9 publicly published papers. The core achievements have been applied to SAIC's new energy vehicles Roewe 550 PLUG IN and Roewe E50, with more than 3500 supporting units; more than 4500 supporting units have been applied to traditional gasoline vehicles MG GT, with a total added output value of 20.2 million yuan, and the economic benefits generated by direct application of EPS are 1.38 billion yuan;
This project helped SAIC Motor Group's Roewe 550 PLUG IN, Roewe E50 and fuel cell vehicles win the first prize in three types of new energy vehicles in the 2014 Biedon Competition.