Vacon NX6, Design Manual

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SIZING OF THE SYSTEM AND PRODUCT vacon • 46
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7
A dedicated tool is available to help in the selection of a correct power unit based on either power
or current profile. Examples of dimensioning based on storage power and current profiles are
displayed in figures below.
The intermediate steps between I
NOM
and I
MAX
can be calculated with the formulas given in the
previous figure. The shape of the output current curve is due to the limitation of the I
1
in the rating
plate and the relation between input and output current of the DC/DC converter. The plateau part
of the curve is due to thermal performance of the DC/DC converter. Current capability of the DC/DC
converter may seem complicated but it simply yields a constant power capability up to the point I
MAX
where current cannot be increased anymore. The relation between current and power can be
examined in the following graphs. Constant power is available as long as the voltage is sufficiently
high.
Figure 47. Power unit selection tool example based on storage current profile
Figure 48. Power unit selection tool example based on storage current profile
Based on the cases in figures above it is advantageous to limit the power at low battery voltage to
limit the current to a reasonable value. This helps to allow the use of a smaller frame size. Filter
size is also proportional to current. Therefore, high energy storage voltage is preferred from the
DC/DC converter sizing perspective.
Select: Define Storage Power
Storage g
voltage g
range
Storage g
Power
Profile
Storage g
Current
Profile
[Vdc] [kW] [Adc]
max voltage 700 350 500 g
nom voltage 375 300 800 g
min voltage 150 81 540
DC-link voltage 750 Vdc Class_5 g
DC-link power 343.0 kW p
DC-link current 457 Adc dc-link
Storage output current 800 Adc storage
wer
Energy storage system parameters
750 Vdc Class_5
34 43.0 0 kW
DC/DC Converter design parameters
Def
0 0
50 50
300 300
350 350
400 400
450
100 200 300 400 500 600 700 800 900
Power [kW]
Voltage [Vdc]
Storage Power Profile
Storage Profile
NXI04605A0T0ISFA1A20000
00
NXI03855A0T0ISFA1A20000
00
700 800
smaller device @3.6kHz
0 0
100 100
200 200
700 700
800 800
900 900
1000
100 200 300 400 500 600 700 800 900
Voltage [Vdc]
Storage Current Profile
Storage profile
NXI04605A0T0ISFA1A200000
0
NXI03855A0T0ISFA1A200000
0
700 800
smaller device @3.6kHz
Power [kW]
Select: Define Storage Current
Storage
voltage
g
range
Storage
Current
Profile Storage
Power
Profile
[Vdc] [Adc] [kW]
max voltage 700 335 235 g
nom voltage 375 400 150
min voltage 150 400 60
DC-link voltage 750 Vdc Class_5
DC-link power 229.8 kW
DC-link current 306 Adc dc-link
Storage output current 400 Adc storage
rent
Energy storage system parameters
750 Vdc Class_5
22 29.8 8 kW
DC/DC Converter design parameters
Def
0 0
50 50
200 200
250 250
300
100 200 300 400 500 600 700 800 900
Voltage [Vdc]
Storage Power Profile
Storage Profile
NXI03005A0T0ISFA1A20000
00
NXI02615A0T0ISFA1A20000
00
700 800
smaller device @3.6kHz
0 0
100 100
200 00
300 300
400 400
500 500
600
100 200 300 400 500 600 700 800 900
20 20
Voltage [Vdc]
Storage Current Profile
Storage profile
NXI03005A0T0ISFA1A200000
0
NXI02615A0T0ISFA1A200000
0
700 800
smaller device @3.6kHz
Power [kW] Power [kW]