The electric vehicles are fast developed as the demand for energy conservation and environment protection. The permanent magnet synchronous motors (PMSM) are widely used in electric vehicles because of their high efficiency. However, due to the DC/AC inverter with fixed switching frequency was used to drive the PMSM, high-frequency vibration and acoustic noise were generated in the PMSM. And the frequency at which vibration and noise are generated is related to the switching frequency of the inverter and its integral multiple. Spread spectrum theory shows that the energies of a fixed high-frequency spectrum can be distributed into a wide range of frequencies. Therefore the concentrated energies can be weakened. This theory can be complied with the PMSM control strategy to help to reduce the high-frequency vibration and noise.

This paper presents control strategies with changing the switching frequency in order to reduce the vibration and noise of the electric motor. Firstly, four control strategies with different switching frequency: fixed switching frequency (FSF), periodic switching frequency (PSF), random switching frequency (RSF) and hybrid switching frequency (HSF) are modeled and simulated by MATLAB-Simulink. During this process of simulation, the influence from the modulate rate and spread width to the reduction of harmonic amplitude was detailedly analyzed. Secondly, these four control strategies are implemented by the dSPACE MicroAutoBoxⅡfor the rapid control prototyping (RCP) test. Thirdly, the vibration and noise tests of the PMSM are complied in the semi-anechoic chamber using software and devices from the LMS Test. Lab. Finally, the results of simulation and tests are compared and analyzed. Based on the simulation and test results, these three optimized control strategies can suppress the high frequency current harmonic amplitude significantly and the noise and vibration reduction difference among them are not apparently. Comprehensive analysis shows that the random and hybrid switching frequency control strategy proves to achieve better the goal of reducing the amplitude of high-frequency vibration and noise.

Mr. Carlos Agudelo, Link Engineering, UNITED STATES

Mr. Marco Zessinger, Link Europe GmbH, GERMANY

Mr. David Antanaitis, General Motors, UNITED STATES

Mr. Michael Peperhowe, dSPACE GmbH, GERMANY

Current standards like the SAE J2789 have provisions for adjusting the brake inertia for regenerative braking systems. However, a comprehensive method to implement the correct brake blending during inertia dynamometer testing in real-time remains elusive. With Hybrid and Battery Electric Vehicles (BEV) propulsion systems on the rise, the need to develop friction couples and braking systems is ever increasing. To better understand new phenomena related to low-temperature burnish, corrosion, brake balance, NVH, and brake emissions, the automotive industry needs to rely on laboratory testing using inertia dynamometers. The main innovation on the approach presented is the ability to have an actual (ego) brake corner in the test environment to provide real-time torque and temperature response during testing,

This oral-only presentation elaborates on critical aspects of HiL simulation for BEV brake blending. What makes this work unique is the focus on the development of working software and working hardware using software ECUs for the battery controller, particular communication protocols with high-speed scenario simulation, and commercially available hardware (HiL and standards dynamometer platforms), and application to real-life cases and driving cycles. The work presents the software and hardware modules; the algorithms to control the ego brake corner; the communication packets; events, and scenario triggers; and the automation of a test cycle – with practical examples. These developments can support early system evaluation, simulation of static and dynamic scenarios, and expand to include multiple ego brake corners.

The optimal brake control in the case of a full electric vehicle must not only guarantee high brake performance but also aim at maximum possible level of energy regenerated during the manoeuvre. Targeting integrated electric vehicle control, the driving comfort should be also considered as a component requiring optimization. These factors have motivated the presented study and allowed to formulate the main objective: Development of optimal brake control strategy based on three criteria – brake performance, energy efficiency, and ride comfort. The research is subjected to a full electric passenger vehicle equipped with four in-wheel motors and an electro-hydraulic brake system. On the first stage of the research, the optimization procedure is proposed for the brake torque distribution. Three domains are chosen for the shaping of the corresponding optimization cost function: the brake performance is being estimated by deceleration tracking during the manoeuvre; the energy consumption is quantified through regenerative energy and tyre dissipation energy; the indicator for the ride comfort (in the case of straight-line braking) is the pitch angle. The verification of the developed brake control functions is carried out using the vehicle simulator in IPG CarMaker and hardware-in-the-loop platform with installed electro-hydraulic brake system. The straight-line braking manoeuvre has been investigated as the case study. The proposed technique allowed to reach an optimal brake force distribution with high level of brake energy recuperation and simultaneous keeping of required safety level. The pitch oscillations caused by the vehicle behaviour at emergency braking have been also reduced as compared with the brake manoeuvre without brake distribution / blending control. The experiments were done on the basis of model- and hardware-in-the-loop simulations. The characteristics of electric motors are deduced from experimental data. The real hardware components of the brake system are used including the hydraulic control unit. The controller is emulated in real-time mode using dSPACE tools. The results of the presented study have showed that an optimal brake control in the case of the electric vehicle allows to achieve a multilateral effect in reduction of the brake distance, increase of brake energy regeneration and improvement of the ride comfort at braking.