Apr 22, 2010 ... This report describes the test results obtained during the test of an electric VW
Golf variant. The focus of the tests was to determine the energy ...
Electric vehicle test: VW Golf variant ECE P.F. van Oorschot, R. Vos DC 2010.036
DC report Eindhoven University of Technology Department of Mechanical Engineering Dynamics and Control Group Eindhoven, May, 2010
This report describes the test results obtained during the test of an electric VW Golf variant. The focus of the tests was to determine the energy consumption of the vehicle at different constant speeds and during normal (sub)urban driving.
Test conditions The vehicle has been tested on the 21st and 22nd of April 2010. During the test the outside temperature was 19 degrees Celsius at average. All tests have been performed with 2 persons in the vehicle, weighing a total of 160kg. The tire inflation pressure was checked and put at the prescribed pressure of 2.5 bar for the front wheels and 3.0 bar for the rear wheels. All measurement data are based on the information display available in the vehicle. Due to the limited time available, no calibration of the measured values has been done. The display provides the following data: speed [km/h], power [kW], current [A], average energy consumption [Wh/km], lowest cell voltage [V], highest cell temperature [°C] and motor temperature [°C].
Vehicle The vehicle tested is an electrified VW golf variant. The vehicle has been converted to a full electric vehicle by ECE cars located in Lochem. Essent is the owner of the vehicle and agreed to make the vehicle available for testing at the TU/e for two days. Vehicle:
VW Golf variant
License:
12-JND-2
Length/Width/Height:
4556/1781/1467 mm
Weight The weight of the vehicle is measured on all wheels to determine the weight distribution. The curb weight is measured without persons in the vehicle and is listed in table 1.
LF
390.0
kg
RF
380.5
LR
410.5 kg
RR
421.5 kg
Weight: Front:
kg
Front
770.5 kg
Rear
832.0 kg
1602.5 kg 48.1 %
Rear:
51.9
%
Table 1: Curb weight The weight distribution is shifted to the rear compared to an original VW golf variant 1.6. This leads to less under steer behaviour compared to the original vehicle. During driving no particular behaviour has been observed. The total vehicle weight of 1602.5 kg is relatively high compared to
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the original VW weight of 1235kg. The conversion process increased the weight by 367.5 kg. To compensate for the higher weight at the rear, extra support springs are mounted. As shown in appendix III. Drive train and components The electric drive train of the vehicle consists of a conversion kit provided by AC Propulsion. The motor is an air cooled 150kW AC induction motor. The motor is coupled to the original VW gearbox, which is locked in second gear. During driving the motor reaches temperatures of up to 110 °C. The inverter, charger and DCDC converter are all integrated in a relatively large, air cooled, box. The box is mounted in the original engine bay. The charger is able to charge up to 6kW DC power, using 32A/230V AC power. The DCDC converter can deliver up to 100A of 12V power. The datasheet of the AC Propulsion set can be found in appendix I. The interior heating of the vehicle is provided by a 3kW external electric water heater, provided by MES-DEA. The air conditioning pump is driven by an industrial air cooled electric motor. Battery The vehicle is equipped with a lithium ion battery pack with a total capacity of 37 kWh. From the gathered data can be concluded that the usable capacity of the pack is 28 kWh, approximately 75% percent of the nominal capacity. The nominal voltage of the battery pack is around 330V, the maximum current drawn from the batteries at full power is 460A. The voltage of the lowest cell drops around 0.1V per 100A current drawn. During driving the temperature of the battery cells reaches up to 48 °C. The complete battery is divided in two separate packs, one under the rear seats and one in the trunk. The battery packs are air cooled.
Energy consumption The energy consumption of the vehicle is measured over a range of constant speeds up to 140 km/h, with increments of 10 km/h. The power consumption of auxiliaries and vehicle systems is not dependant on the vehicle speed and is measured separately, during standstill. The power consumption of these systems is listed in table 2. Consumer
Power
Vehicle systems only
0.3 kW
Vehicle Systems, lights
0.5 kW
Vehicle systems, lights, heating
3.5 kW
Vehicle systems, lights, air conditioning
4.1 kW
Table 2: power consumption of vehicle systems and auxiliaries
During the constant speed consumption test no auxiliaries are used, only the vehicle systems are online. The results of the constant speed tests are listed in table 3.
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Power [kW]
Consumption
Speed [km/h]
Trial 1
2
3
Average
Wh/km
10
0.9
1
1
1.0
96.7
20
2.2
2.3
2.2
2.2
111.7
30
3
3.3
3.1
3.1
104.4
40
4.1
4
4.1
4.1
101.7
50
5.5
5.9
5.4
5.6
112.0
60
7.3
8
8.5
7.9
132.2
70
9.7
11.5
10.4
10.5
150.5
80
11
11.1
13
11.7
146.3
90
14
15
15.2
14.7
163.7
100
18.8
22
21.1
20.6
206.3
110
24
25.4
23.8
24.4
221.8
120
31
28.9
31.9
30.6
255.0
130
38.8
36.8
37.8
290.8
140
44
43
43.5
310.7
Table 3: Energy consumption at constant speed
As expected, the energy consumption increases rapidly at higher speeds. The vehicle drag is the most important factor for the energy consumption at higher speeds. The use of auxiliaries such as the heating or air conditioning has a large impact on the energy consumption of the vehicle. Especially at low speeds, the power consumption of the auxiliaries is high relative to the traction power. At a speed of 40 km/h the power consumption of the heating or air conditioning is as high as the required traction power. At this speed the range of the vehicle is split in half when the heating or air-conditioning is used. Figure 1 shows the energy consumption characteristics with and without auxiliary loads. This clearly shows the negative influence of auxiliaries on the energy consumption and range at low speeds.
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Figure 1: Energy consumption characteristics at constant speed, with and without heating
Energy consumption during (extra)urban driving. To determine the average energy consumption during (extra)urban driving a specific route is driven. The route is chosen as a representative route for driving in the Netherlands. During driving the speed is kept close to the speed limit. The route has a length of 26.2 km of which 36% is highway, 23% is suburban roads and 41% km is urban traffic. The route is driven in 38 minutes, at an average speed of 42 km/h. The average energy consumption over the route is 230 Wh/km. Considering the 28 kWh usable capacity of the battery this results in an average range of 122 km. Table 4 shows the average consumption measurements during the tests, as well as the percentage of regenerative braking. A description of the complete route can be found in appendix II.
Distance Energy Regenerative Consumption
Trial 1 26.2 6.0 7.4 229
2 26.2 6.0 8.4 230
3 Average 26.2 26.2 km 6.1 6.0 kWh 9.8 8.5 % 232 230 Wh/km
Table 4: Average consumption during suburban driving
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Performance The performance of the vehicle has been measured. The acceleration performance of the vehicle is good at high speeds, but quite slow at low speeds. The reason for this is a software limit on the motor torque at low speeds. Table 5 shows the acceleration performance at different speeds.
Time [s]
Acceleration
Trial 1
2
3
0-50 km/h 0-100 km/h
7.1 13.8
7.3 14
7 14
13.5
7.1 s 13.8 s
50-80 km/h
3.9
4.3
3.9
4
4.0 s
80-120 km/h
6.6
6.4
6.4
4
Average
6.5 s
Table 5: Acceleration performance
The top speed of the vehicle is limited to 140 km/h. Regenerative braking The regenerative braking performance of the vehicle has been measured at different speeds. The vehicle utilizes regenerative braking only on release of the throttle pedal. The brake pedal does not influence the regenerative braking power and only controls the hydraulic brake system. The regenerative braking power is surprisingly low compared to the maximum traction power of 150 kW. Table 6 shows the regenerative brake power at different speeds.
Power [kW]
Speed [km/h]
Trial 1
2
3
50 80
7.3 11
7.3 11.5
7.2 12.2
7.3 kW 11.6 kW
100
14.3
15.2
15.6
15.0 kW
120
19
19.5
19.2
19.2 kW
Average
Table 6: Regenerative braking power
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Appendix I: AC Propulsion set datasheets
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Appendix I
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Appendix I
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Appendix II: (sub)urban route for consumption tests
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Appendix II
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Appendix II
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Appendix III: Pictures of vehicle and component location All pictures can be found at: \\Wtbfiler\control systems technology\VDL\Studenten\projects\VW Golf ECE test
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Appendix III
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