Comparisons of reaction times for a modified four-wheel electric vehicle equipped with a permanent magnet synchronous motor under neutral-sliding-status, FOC based braking, and short-circuit braking were conducted. The basic block diagram of FOC is shown in the figure. Also, due to easily available digital signal processors, there is a boost in the digital control market in the field of motor and power control. With the mathematical processing power offered by the microcontrollers, advanced control strategies can be implemented, which uses mathematical transformations in order to. Due to these benefits, PMSM are widely used in modern variable speed AC drives, especially in electric vehicle (EV) and hybrid EV applications. Compared to the regenerative brake and rheostatic brake, the proposed braking system has a powerful braking torque and shorter reaction time. 4 Field Oriented Control (FOC) 4.1 Introduction In order to achieve better dynamic performance, a more complex control scheme needs to be applied to control the PM motor. This provides a smoother and more accurate motor control than sinusoidal commands with Hall feedback. When the motor receives a brake command, the controller changes the inverter-switching sequence to generate reverse torque and a magnetic field to complete the driving or braking function using field-oriented control (FOC). It calculates the rotor position angle of the motor by detecting variation in the stator current and completes a closed-loop control. The main idea of vector control was to overcome drawbacks of scalar control methods by using a dynamic model of an ACIM with voltages, currents, and fluxes. AVR32723 32126A-AVR32-06/09 3.3 System Overview As shown Figure 3-2, the 3-phases current are measured and one Hall Effect feedback is used to compute field oriented control algorithm. Field-oriented control (FOC), widely called just vector control, appeared in the late 1960s with its first introduction by Hasse and Blaschke. Due to a permanent magnet rotor, PMSM motors have very high efficiency, reliability and are fast in response. The block diagram of the drive is presented and. Field Oriented Control Block Vectorial Command Speed Regulation loop Current Regulation loop Speed Target. This paper details the implementation of Field Oriented Control (FOC) of Permanent Magnet Synchronous Motor (PMSM) using indirect current control method. This research proposes a sensor-free, integrated driving and braking control system that uses a space-vector-pulse-width module to synthesize stator current by purpose. The principle of field oriented control is developed in the contextof a squirrel cage induction motor drive. Id and Iq are therefore slow-changing DC values, making them a lot easier to process by the other blocks.Most electric vehicles use regenerative brakes, since this kind of braking system design recycles electromotive force to increase electric power endurance during braking. The Clarke & Park block represent mathematical processing that, together with the angle information, measures the Quadrature current Iq and Direct current Id 'as seen' from the rotor point of view. While the field inside the stator is 3 phase rotating magnetic field, the rotor which rotates at the same speed as the rotating field sees a constant force. Calculations are used to transform the three-phase signals into two phases that are easier to control and implement in the motor control circuit.

In a brushless motor, the stator field is produced by current flow in three equally spaced stator windings. The figure below shows the classic representation of FOC found in all literature. Field oriented control (also known as vector control) is a technique used to generate a 3-phase sinusoidal modulation which then can be controlled in frequency and amplitude. currents are easily measured externally while fields (actually flux) are not. Field Oriented Control is about measuring these two components and adjusting the phase of the voltage in order to bring the Direct current to 0, leaving only Torque current. Since the magnetic field is the direct result of current in the coils, the current can likewise be decomposed into current that causes the perpendicular pull - called Quadrature or Torque current, and one that causes the outward pull - called Direct current or Flux current.