MCSact/cont/ref  = actual,    control    and    reference

torque on crankshaft

p = pulley

pk  = number   of   pole   pairs   (k =

BSG, CS)

Rk  = coil resistance (k = BSG, CS)

RpAT   = wrap radius on automatic   belt tensioner pulley

Rpi  = wrap radius on i-th pulley (i =

AC, BSG,CS,IDL)

T = belt tension

Vdk = direct voltage (k = BSG, CS) Vqk = quadrature voltage (k =

BSG, CS)

αAT   = wrap angle of the automatic ten- sioner pulley

θ = angular displacement of the pul- ley

θBSGact/cont/ref  = actual, control and reference an-

gular of displacement of belt- starter generator

ωBSGact/cont/ref  = actual, control and reference an-

gular velocity of belt-starter gen- erator

ωCSact/cont/ref  = actual, control and reference an-

gular velocity of crankshaft pul- ley

ωpAC/AT/BSG/CS/IDL  = angular    velocity    of    the    air

conditioning, automatic tensioner, belt-starter generator, crankshaft and idler pulley

ωBSG/CS   = angular velocity of belt-starter

generator and crankshaft

BSG and the crankshaft of the ICE allows to reproduce the different operating conditions of the iBDS. In  addition, it is fundamental for taking into account the crankshaft oscillations due to the overlapping of the harmonics. The harmonics are generated via the Electronic Control Unit (ECU) in a predictable and repeatable manner.

The aim of this work is to describe the design and the obtained characteristics of the belt transmission test rig, highlighting its versatility. At first the main components of the test rig are described and complete details regarding the control and monitoring system are provided. Secondly the model of the system, pided into its main components, is presented and used for the definition of the specifications of the two electric motors.

2. EXPERIMENTAL SETUP AND TEST RIG CHARACTERISTICS

The design was performed to obtain the maximum ver- satility and allow the test rig reproducing different kind of BDS, both for what the mounting solutions and the characteristic of the components are concerned. The aim of the present section is to give an overview of the test rig and illustrate its main characteristics.

2.1 Mechanical layout

Fig. 1 shows the geometric configuration of the test rig from the top view. The layout reproduces the setup of a real engine front end, where the BDS connects five com- ponents: crankshaft, BSG, air conditioning compressor, automatic tensioner, idler pulley. The power is transmitted by a V-ribbed belt with 5 ribs. The layout was reproduced in a horizontal plane to have a uniform distribution of the forces acting on the frame and to avoid possible bending stresses on the bearing structure. The mounting solutions of the pulleys were adopted to allow the substitution of each pulley with others of different radii or coupled with belts of different number of ribs or type. The   crankshaft