Comparison of energy saving effects of hybrid excavators
The energy saving effect of the hybrid excavator is one of the key indicators of its performance. The prototype system, series system and parallel system are in heavy load excavation load spectrum as load input. The fuel consumption simulation results are shown in Figure 11, which can be seen from the figure, and the ordinary system fuel consumption is 540g, and the series system fuel consumption is 362g, parallel The system fuel consumption is 330g, compared to the normal system string, and the energy-saving effect is increased by 36.1% and 40.7% respectively. However, it is necessary to explain that the fuel consumption model in the string, the parallel hybrid excavator simulation model does not include the equivalent engine fuel consumption generated due to the change of the battery, from the string, the parallel system SOC fluctuation curve can obtain the fuel consumption statistics 300s Time The SOC of the inner series system battery group changes from 0.6 to 0.65, and the contact of the battery pack SOC is changed from 0.6 to 0.64, the calculation method of equivalent fuel consumption is as follows (5):
Malsoe is an equivalent fuel; ASOC is a battery SOC conversion; QAUR is a battery pack capacity, and the series system is 2.96kWh, which is 1.96kWh: 7A for fuel consumption, which can be combined with Figure 13 engine operating point distribution and Figure 50,000 The characteristic curve is obtained, and the series system takes 230 g / kWh, and the contact is taken from 240 g / kWh. The comprehensive fuel consumption of the battery SOC fluctuations is finally considered, for example, Table 3.
Fig. 12 is a characteristic graph of the hydraulic pump, before the hydraulic pump enters the power P1, the power of the hydraulic pump varies with the rotational speed fluctuations, and the fluctuation of the load directly affects the rotational speed and power output of the engine. The normal power system engine directly drives the load hydraulic pump (constant power variable pump), so the engine operating point is frequent, and the fuel efficiency is very low, and the fuel consumption curve appears as a curve with a large slope fluctuation. The series system, due to the power source and load, there is no direct mechanical hard connection, the fluctuation of the load cannot directly affect the operating point of the engine, and thus can more simply controlling the operating point on the economic fuel consumption curve, the final system is low, stable, consumption The oil curve is expressed as a straight line that is substantially stable slope. The line simulation start segment has no fuel consumption because the load is low, the battery has a higher SOC, so it is driven separately by the motor.
Parallel system, the energy saving effect is in the above circumstances, the peak of the auxiliary power source has caused the engine operating point to fluctuate but always around the economic fuel consumption point. In addition, the fuel efficiency of the hybrid system can improve the fuel efficiency of the excavator can also be verified from the improvement of the engine operating point. Figure 13 is a fluctuation situation of the three-power system engine operating point collected by the test stage, and the engine operating point is obtained by using the hybrid system. Obvious improvement. In the fuel consumption curve reflects the oversuvenation of the serial interstitial and there is more, because all energy in the series system experiences the energy conversion link of the generator and the battery, and the increased energy conversion link reduces the overall fuel efficiency.
