THE EFFECT OF A PERMANENT MAGNET SYNCHRONOUS MACHINE IN THE ELECTRIC ENERGY RECOVERY SYSTEM S EFFICIENCY IN A HYDRAULIC FORKLIFT

Transcription

1 THE EFFECT OF A PERMANENT MAGNET SYNCHRONOUS MACHINE IN THE ELECTRIC ENERGY RECOVERY SYSTEM S EFFICIENCY IN A HYDRAULIC FORKLIFT Tatiana Minav 1

2 The purpose of this research: Recover efficiently electric energy in an electrohydraulic forklift system Analysis of the recovery efficiency Study the effect of PMSM on the energy recovery efficiency. 2

3 PMSM-drive PMSMs have in general: high efficiency high overloadability good controllability In principle a PMSM drive should give the best opportunities to reach a high efficiency in our application 3

4 Typical hydraulic flow chart of a forklift The potential energy is lost in the control valve when lowering the mass 4

5 General overview of the test setup /Generator /Motor The potential energy is recovered 5

6 Comparison of theoretical efficiencies of different hydraulic pump types Work area 6

7 Parameters of PMSMs used in the study According to calculations: For lifting a 920 kg load 45 Nm is needed at the pump shaft with speed 2000 rpm Two different approaches utilizing the good overloadability of PMSMs were studied. Small PMSM: PMSM CFM90M: T n = 14.5 Nm, In= 10.1A, T max = 52.2 Nm, Imax= 40 A Big PMSM: PMSM CFM112M: T n = 31 Nm, In= 35 A, T max = 108 Nm, Imax= 140 A 7

8 Small PMSM: Changes of the phase current depending on load during lifting Speed, Mass of load, kg rpm 0 kg 690 kg 920 kg Torque/Nm Current/A Torque/Nm Current/A Torque/Nm Current/A Big PMSM: Speed, Mass of load, kg rpm 0 kg 690 kg 920 kg Torque/Nm Current/A Torque/Nm Current/A Torque/Nm Current/A

9 Total Efficiency Axial Piston Hydraulic Motor used as pump, upwards with small PMSM Efficiency [%] kg 920kg 0kg Speed [rpm] Max efficiency for Axial Piston motor 80% (0kg) for upwards. 9

10 100 Total Energy Efficiency Axial Piston hydraulic motor, small PMSM, downwards Efficiency [%] kg 920kg 0kg Speed [rpm] Max efficiency for axial piston pump 62%(920kg) and 51%(0kg). 10

11 100 Total Efficiency Axial Piston Hydraulic Motor used as pump, upwards with big PMSM Efficiency [%] kg 920kg 0kg Speed [rpm] Max efficiency for Axial Piston motor with new motor 72% (920kg) for upwards 11

12 100 Total Energy Efficiency Axial Piston hydraulic motor, big PMSM, downwards Efficiency [%] kg 920kg 0kg Speed [rpm] Max efficiency for axial piston pump with new motor 68%(920kg) and 47.5%(0kg). 12

13 Comparison of total efficiencies for downwards with 920 kg load and 0kg load 0 kg 920 kg Speed, [rpm] Total efficiency small PMSM motor, [%] Total efficiency big PMSM motor, [%] Difference, [% units] Total efficiency small PMSM motor, [%] Total efficiency big PMSM motor, [%] Difference, [% units] ,78 23,79 8,01 6,50 27,22 20, ,81 42,97 2,17 28,46 52,52 24, ,63 46,76-1,87 42,82 61,53 18, ,91 47,37-3,54 52,61 65,64 13, ,66 45,95-5,71 58,11 67,47 9, ,68 43,72-6,96 61,52 68,96 7, ,96 41,30-7,66 65,64 66,25 0, ,00 38,05-8,95 64,68 67,93 3, ,74 34,68-9,06 65,55 67,03 1, ,49 32,59-10,90 66,18 66,70 0,52 13

14 Comparison of total efficiencies for upwards operation with load 920 kg and 0kg load 0 kg 920 kg Speed, [rpm] Total efficiency small PMSM motor, [%] Total_efficiency big PMSM motor, [%] Difference, [% units] Total efficiency small PMSM motor, [%] Total_efficiency big PMSM motor, [%] Difference, [% units] ,98 62,00 21,02 19,72 52,77 33, ,76 69,88 11,12 39,87 62,92 23, ,44 71,10 6,66 49,09 68,46 19, ,14 67,64 0,49 55,45 71,33 15, ,41 68,34 0,94 59,64 72,95 13, ,59 65,79-1,80 61,81 73,50 11, ,98 65,13-2,85 64,12 73,63 9, ,86 64,15-2,70 64,74 73,21 8, ,46 62,37-3,09 65,60 72,74 7, ,44 56,26-8,18 65,74 72,50 6,76 14

15 Conclusion For Speed 200 rpm: Improving total efficiency of the setup with axial piston hydraulic motor-pump with big PMSM for 0 kg load 8% in total efficiency downwards for 920 kg load 20 % in total efficiency downwards for 0 kg load 21% in total efficiency upwards for 920 kg load 33 % in total efficiency upwards 15

16 Conclusion For Speed 2000 rpm: Improving total efficiency of setup with axial piston hydraulic pump-motor with big PMSM for 920 kg load 0.52 % in total efficiency downwards for 920 kg load 6.7 % in total efficiency upwards 16

17 Thank you.. Presenter: Tatiana Minav 17