| The electromagnetic regenerative suspension researched in this doctoraldissertationis an innovative suspension system, retained the spring for supporting the vehicle massand absorbing the road vibration, and replaced the conventional damper with regenerativedamper. The suspension linear movement was translated into rotary movement byball-screw and net, and then drove the motor to generate electricity, in the meanwhileattenuated the vibration between wheel and vehicle body. As a new energy-saving way, ithas broad application prospects, especially for new-energy vehicles. Combined with theproject of the key issues research of regenerative suspension for vehicle, the paper mainlyinvolved in the following six parts:1. Compared with other types of regenerative suspension, electromagneticregenerative suspension with ball-screw and nut has unique advantages. However, thecurrent structure cannot meet the actual installation and usage requirements for itscomplicated structure and large size. So the structure was redesigned by putting the motorabove vehicle fenders, and only kept the movement transforming and connecting parts insuspension space. Benefitted by this design, the installation space was minimized and theworkingenvironment of regenerative motor was improved, also, the active suspension canbe achieved by new structure.2. The primary problem of replacing the conventional damper with motor is that theconstant torque and constant power characteristic of motor does not match the dampingcharacteristic of the convention damper. The new nonlinear regenerative dampingcharacteristic with three stages was proposed by combined two characteristics mentionedabove. Through theoretical study on the two important critical speeds of nonlineardamping characteristic proposed, the critical speed for constant damping force and itsadjusting coefficient were obtained based on1-dof system model. Simulation results showthat the performance of regenerative nonlinear damping is superior to the semi-active andon-off damping.3. The other key issue for regenerative suspension is the influence of inertia massintroduced by rotary parts of motor and ball-screw on the amplitude-frequency characteristics of the suspension. The vehicle body and wheel resonant frequencyequation of regenerative suspension was deduced from structure modal analysis methodand showed that the two resonant frequencies were shifted to small values as the inertiamass. The transformation characteristics of regenerative suspension show that the inertiamass mainly has bad influence on vehicle ride performance near the wheel resonantfrequency. What’s more, the influence of parameters of regenerative system on RMS ofvibrationresponse was evaluated, and based on the body subjective evaluation, thequantitative requirements of inertia mass was obtained.4. A high power regenerative motor is needed to satisfy the required suspensiondamping force, if there is no conventional damper. Such scheme is unsatisfactory,therefore a new scheme of regenerative nonlinear damping combined with a conventionaldamper of small damping was proposed. After the parameters matching and simulation,the results show that new scheme can minimize the motor power needed while recyclingmost of vibration energy.5. On the basis of analyzing the factors influenced the energy recycle of suspensionvibration, and it was conclude that the energy which can be regenerated is proportional tothe vehicle speed, suspension stiffness and road roughness. The approximate formula ofpower dissipated by damper is also deduced. The model of regenerative motor and batterywas built and simulated for its performance evaluation.6. Produced the prototype of regenerative damper and motor controller, builtitsperformance testing platform, and the characteristics of regenerative system, energyrecovery and damping was tested and validated.The results shows that the performance ofmotor controller, the generating efficiency of motor, the charging characteristic of battery,and output characteristic of regenerative damper can match the requirements. It is alsorevealed that the regenerative motor should be controlled to satisfy the requirements ofdamper. Without proper control, not only dead-zone of motor cannt be eliminated, butalso damage will be caused for motor when its speed was too large. |
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