Electric drive system technologies - Propulsion Systems for Hybrid Vehicles - page 265

Solution:

(a) The d - q components of the stator voltage. Referring to the phasor diagram:

U q ¼ E q þ R ph I q þ X d I d ; U d ¼ R ph I d þ X q I q

Substituting into the above equation after solving for E q ¼ 55 V pk , U q ¼ 73.3 V pk
and U d ¼ 64.13 V pk .

(b) For the stated value of g ¼ 15 , the rated stator current given results in

p I r cos g ;

p I r sin g ;

I q ¼ I q ¼ 348 A pk ; I d ¼ I d ¼ 92 : 5A pk

(c) The input power requires first a calculation of the power angle, d , which can
be found easily from the components of U s in the equation in (a) as

d ¼ sin 1 U d

U q ¼ sin 1 64 : 1 73 : 3 ¼ 1 : 04

ð rad Þ

Next, compute the input electrical power using the classical synchronous machine
relation shown as

3
2

U s E q
X d

P e ¼ sin d

Substituting into the above equation results in P e ¼ 37.5 kW of input electrical
power. The power inverter shown must be sufficiently rated to process this
continuously.

5.2.3 Design essentials of the SPM
In this section, the SPM machine will be treated from a hybrid design vantage
point. The objective is to design an SPM as an M/G for a mild hybrid vehicle. The
design process will illustrate the important features of machine target setting,
electromagnetic design and modelling.
First, we will briefly review the types of electric machines available for the
hybrid propulsion M/G set. Figure 5.16 illustrates six types of electric machines
that should be considered for this application. The machine types are as follows:

Surface permanent magnet . This is the most basic of permanent magnet elec-
tric machine designs. PMs are bonded to the surface of the solid rotor back iron
that is, in turn, fitted to the high carbon steel (4,150 or equivalent steel) shaft.
Rotor back iron is necessary as a flux return path, and this core may be either
solid or laminated depending on application.

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