Paper Contents
Abstract
Power & signal multiplex transmission (P&SMT) is a technique that uses power electronic circuits for communication signal transmission. In this paper, a three-phase cascaded multilevel inverter-based P&S MT system is proposed. The proposed method can transmit communication signals without using a Controller Area Network bus, thereby reducing the wiring cost of the conventional electric vehicle (EV) communication system. The designed system can achieve motor speed regulation and battery balance discharging for EVs. With the combined pulse width modulation scheme and frequency shift keying method, both power and communication signals are transmitted successfully in a simulation model implemented in MatlabSimulink. By evaluating the bit error rate of the transmitted signal, the maximum signal rate of the proposed system is determined as 600 bits.Keywords: Cascaded Multilevel Inverter, Electric Vehicles. 1.INTRODUCTIONThe challenges posed by climate change are spurring experts and researchers to investigate the alternatives for fossil fuels to achieve carbon dioxide emissions reduction. Nowadays, the application of electric vehicles provides a feasible solution for energy saving and emission reduction in the automotive industry. Compared to traditional internal combustion engine cars, electric vehicles (EVs) not only produce fewer air pollutants such as CO and NOx but also generate less noise 1, 2. Furthermore, if the battery of the EV is charged at night, it can avoid the peak of power consumption, which is beneficial to the grid to balance the load and reduce the cost 3. Since various subsystems such as the motor control unit (MCU) and the battery management system (BMS) in an EV require communication with the transmission control unit (TCU), it is necessary to employ an effective method to realize signals transmission 4, 5. One of the approaches that is widely accepted by manufacturers and researchers for data transmission in EVs is through a Controller Area Network (CAN) bus because of its high reliability and high communication baud rate 6, 7. The general powertrain structure of an EV is exhibited in Fig.1. Some conventional power systems for EVs employ a DCDC converter to boost the battery voltage for a 2-level inverter 8, 9. This approach can have high voltage change rates (dVdt), which leads to high switching losses 8. Moreover, such a system is expensive and has low power density because of the utilized bulky inductors for the DCDC boost converters 9. Although the traditional EVs realize their internal communication through the CAN bus, the communication channel and the power transmission line are still two independent sections, and the whole system can still be optimized. This paper proposes a power & signal multiplex transmission (P&SMT) method to transmit both power and communication signals through a three-phase multilevel inverter circuit for EVs. The individual devices of the multilevel inverter have a much lower switching loss than that of a 2-level inverter, and a DCDC converter is not required since the cascaded multilevel inverter itself can boost the battery voltage. In the proposed system, the power conversion is realized by the pulse width modulation (PWM) method, and the transmitted signals are modulated by the frequency shift keying (FSK) approach. Instead of using a CAN bus as a communication channel in the up-to-date EVs, the proposed approach can greatly reduce the expenditure on the communication system because the power and signals are transmitted simultaneously through the same power line. The remainder of this paper is arranged as below. Section II reviews some relevant literature about the P&SMT technique. Section III describes the structure and the P&SMT mechanisms of the proposed system. The simulation results are provided in Section IV. Section V draws a brief conclusion at the end of this paper.
Copyright
Copyright © 2023 s raj kumar. This is an open access article distributed under the Creative Commons Attribution License.
