# Motor Vector Control Based on Speed-Torque-Current Map
## 1 Introduction  
As the only source of propulsion, the dynamic characteristics and the performance of the motor are very important to vehicles. In order to meet the needs of vehicle research, the study of motors from static control strategy to dynamic control strategy can make the vehicle run more efficiently. The efficiency and torque characteristics of the motor directly determine the effect of the control strategy. It also has a direct impact on the power loss of the motor and the mileage of the vehicle. In recent years, the permanent magnet synchronous motor (PMSM) is increasingly used as the power source in pure electric vehicles. Multi-power source systems are also taken seriously because of their wide efficiency range and multi-mode flexibility [1]. At present, the drive control strategy of a multi-power driven vehicle is mainly designed based on the static characteristics of the transmission system components [2]. In [3], a rule-based control strategy for a dual-motor coupling driven pure electric vehicle is designed to obtain the optimal acceleration performance. In [4], the dynamic programming algorithm is used to optimize the mode switching threshold value of a dual-motor coupling electric drive system with rotational speed coupling mode, and the optimized control strategy significantly improves the economic efficiency of the vehicle. [PERSON] [5] comprehensively considered the problem of motor temperature rise, which leads to its efficiency and torque decline in the process of designing the coordinated control strategy of the whole vehicle powertrain. It effectively reduces the frequency of motor failure due to the temperature rising. [PERSON] [6] investigated the PMSM control system through combining the method of rotor field-oriented control and the space vector control strategy. [PERSON] [7] established the dynamic model of the PMSM and the efficiency model of the invertermodule of the motor controller. He studied the speed and torque characteristics of the motor, as well as size and quality characteristics, and designed the control strategy based on torque compensation in the dynamic mode and economic mode. In order to improve the performance of PMSM when it is used as a motor to drive the vehicle, the working principle of this type of motor has been thoroughly analyzed, and its current vector control scheme is optimized [8; 9; 10; 11; 12; 13; 14; 15]. Most of the motor dynamic models established by the above scholars are used to study the speed and torque response and energy consumption performance, but the influence of motor dynamic control on the vehicle drive control strategy has not been further studied. Furthermore, if only the static characteristics of components are considered in the formulation of the control strategy of the driving system, there will be a big discrepancy between the operating state of the system and the actual operation process. The influence of dynamic process and control on the performance of the vehicle cannot be ignored; otherwise, performance errors of the vehicle may be caused. The major defects of the static model are as follows. (1) In the static model, the speed and torque of the motor can step change; that is, the working point of the motor can step change instantaneously. However, in practical running, the change of the speed and the torque is not an ideal step process. If the static model is used as the basis of the driving strategy, its dynamic and economy performance have a large deviation from the actual running. (2) The actual operation of the motor is affected by the control parameters, and there is always torque fluctuation. However, these characteristics cannot be reflected in the static model. (3) In the process of coupling drive, the efficiency of different working modes is only considered in the static model, but the mode-switching process and the energy loss are ignored in the process.