(1) and BSG (3) pulleys were mounted on the shafts of two BoschRexroth IndraDyn H electric motors. The crankshaft is powered with motor MSS182D-0260 and the BSG with MSS102D-0800. Their specifications are listed in table 2. The frameless configuration of the two motors and their liquid cooling allowed to design their case to obtain the best integration with the rest of the test rig. On the shaft of the two motors were mounted two equal modular magnetic encoders ERM 2984 by Heidenhain (line count 192, 1Vpp sinusoidal incremental signals, maximum rotational speed 47000rpm, power supply 5Vdc). The angular speeds of the crankshaft and BSG pulleys are additionally monitored by means of two optical tacho sensors. These devices employ

Table 2. Characteristics of Electric  Motors

Function Rated Speed Max Speed Rated Torque Max Torque Rated Power Rated Current Max Current

n [rpm] nmax [rpm] M [Nm] Mmax [Nm] P  [kW ] I [A] I [A]

Crankshaft 2600 12000 140 320 38.1 71 200

BSG 8000 22500 20 45 16.8 24 69

Table 3. Parameters of Accessories

Position Accessory Pulley  Diameter [m] Coordinates  [X,Y]  [m] Rotational  Inertia [kgm2]

1 Crankshaft 126.0 e-3 [0;0] e-3 53.4 e-3

2 Idler 65.0 e-3 [136.2;216.0] e-3 24.6 e-6

3 Alternator 54.0 e-3 [220.4;269.0] e-3 4.5 e-3

4 Air Conditioning 109.2 e-3 [177.1;97.0] e-3 2.2 e-3

5 Automatic Tensioner 65.0 e-3 [76.3;64.8] e-3 24.6 e-6

Fig. 1. Belt Drive Layout. The system is composed by:

(1) crankshaft, (2) idler pulley, (3) BSG, (4) AC compressor, (5) automatic tensioner

a photoelectric sensor (OPB705 by Optek, power supply 5Vdc) that detects the reflection of a line pattern printed onto the pulley surface. In order to measure the tension of the belt both in static and dynamic  conditions the idler pulley (2) hub was instrumented with a load cell (DB-DA-750-17 by Magtrol, nominal force 750N , power supply 5Vdc). The AC  compressor (4) was  mounted   as a unit to have the possibility to use it as a load, even though during the first experimental phase it will not be actuated and will behave just as an additional idler pulley. The automatic tensioner (5) installed on the test rig is a prototype that is able to adjust the belt tension in response to a software request input. The angular displacement of the tensioners pivot is measured by means of a magnetic angle sensor module (KMA210 by NXP, angle resolution 0.04deg, maximum angle 180deg, external magnetic field strength 35kA/m, power supply 5Vdc).