**5. Conclusions**

vector trajectory is used in the constant torque region to generate maximum torque. The voltage-limited maximum output trajectory makes the motor increase to higher speed.

(MTPA) trajectory. The maximum output torque is usually achieved in point A in Figure 8,

Region II (*ω*<sup>1</sup> <*ω* ≤*ω*2): when the speed reaches *ω*1 and stator voltage increases to maximum voltage, the current vector starts to moves from A to B along the current limit circle as the rotor

Region III (*ω*<sup>2</sup> <*ω*): when at point B, *ω*=*ω*2, the current vector starts to move along the voltagelimited maximum output trajectory, where stator current *Is* < *I*lim, stator voltage *Vs*=*V*lim [26].

Figure 10(a) illustrates the block diagram of the novel flux-weakening control based on nonlinear current compensation. Part 1 is the torque controller in the constant torque region.

**Figure 10.** (a) The block diagram of the novel flux-weakening control based on nonlinear current compensation. (b) d-

speed increases. In this region, stator current *Is* = *I*lim, stator voltage *Vs*=*V*lim

*4.3.3. Proposal of novel flux-weakening control based on nonlinear current compensation*

*<sup>q</sup>* are constant values given by the maximum torque-per-ampere

\* is the output of the P1I speed controller, and then decomposed into

\* according the maximum torque-per-ampere trajectory

Region I (*ω* ≤*ω*1): *i*

22 New Applications of Electric Drives

The current command *i*

axis current modification

d- and q-axes components, *i*

*<sup>d</sup>* and *i*

where stator current *Is* = *I*lim, stator voltage *Vs* <*V*lim

*s*

until the current regulator begins to saturate.

*dx* \* and *i qx* In this chapter, some fundamentals of the electric drives in alternative fuel vehicles are first introduced including application background and existing challenges. Then the multidomain transient unified modeling of AFV electric drives is newly defined at aim of efficiency improvement and ESS lifetime extension. The active power filter (APF) in the DC system is proposed for the elimination of ESS chaotic currents. The sensorless drive for the traction motor using a fixed boundary layer sliding mode observer is described in detail, as well as the fluxweakening controller using nonlinear current compensation, in order to enhance traction motor control precision and dynamic performance. The definitions and strategies discussed in this chapter may contribute to research and development of brand-new electric drives applied in EVs or HEVs.
