Download Poor input power factor

POWER ELECTRONICS
Multi-Step VSI
vs
GTO CSI
01 GTO CSI – Current Source Inverter – 6 pulses – with transformer
Font: High-Power Converters
and ac Drives. By Bin Wu
LINE UP SIDE
 Poor input power factor at low loads
with SCR
 High Input harmonics, input and
output filters needed.
 CMV is transferred to the transformer
winding
 Low overall efficiency due to
transformer and high switching
losses.
INVERTER
 Link inductor stores the energy
 Requires controlled front end that
add extra complexity.
 High switching losses
 High power consumption at low
loads.
 High current stress on output
capacitors
 Narrow speed range
MOTOR SIDE
High motor THDi at low loads or low
frequency.
CMV stress on motor winding due to
input transformer (x1.5)
Potential torsional resonance between
motor & capacitors
 Limited starting performance &
dynamic response. (Not used for
conveyors, cranes, mills, …etc.)
Power Electronics España S.L. © reserves the right to modify the content without prior notice
02 GTO CSI – Current Source Inverter – 6 pulses – without transformer
Font: High-Power Converters
and ac Drives. By Bin Wu
LINE UP SIDE
 Poor input power factor with SCR
front end
 Highly potential LC resonances
 High Input harmonics, input and
output filters needed.
INVERTER
MOTOR SIDE
 Link inductor stores the energy
 Requires controlled front end that add
extra complexity.
 High switching losses
 High power consumption at low loads.
 High current stress on output
capacitors
 Narrow speed range
 High motor THDi at low loads or low
frequency.
 Potential torsional resonance between
motor & capacitors
 High CMV stress on motor winding,
CMC filters and double isolated motor
needed. (x2)
 Limited starting performance (overload
& torque)
 Slow dynamic response. (Not used for
Power Electronics España S.L. © reserves the right to modify the content without prior notice
conveyors, cranes, mills, …etc.)
03 VSI – Multi Step PWM modulation with low Voltage IGBt
STORED ENERGY
LINE UP SIDE
INVERTER
MOTOR SIDE
 High power factor
>0.9 under any load
condition
 High efficiency >96%
over 20% load.
 Low harmonics
THDi<5%
 No additional line-up
costs
 DC link Capacitors
store the energy
 Large unstressed low
voltage parts count,
but reduced spare
parts.
 Redundancy option
adds parts and
decreases MTBF
 Low switching losses.
 Available N+1,2,3
redundancy
 Regeneration available
with IGBt rectifier
 Low motor THD at any
load and frequency
condition
 High break away
torque
 High overload capacity
(150%)
 Fast and accurate
transient response
 Reduced CMV stress
on motor winding (x1)
Power Electronics España S.L. © reserves the right to modify the content without prior notice
04 Summary
Efficiency
Full Power and Frequency
Low Power (50%)
Reliability
Components
MTBF
Power Quality
Harmonics
Potential Resonance
Power Factor
Motor issues
Break away torque
Dynamic response
THDI/HVF
CMV (Common Mode Voltage)
GTO-CSI
VSI- Multi Step PWM
93%
86%
96.5%
96%
Low, high components count
1.5 years
High, low components count
(Low voltage & redundant)
>10 years
High for SCR, lower for IGCTs or Multi-pulse
systems (12p, 18p)
High for LC filters
Low for SCR
Low, at any load condition meets
IEEE519
No
High, at any load condition
Low
Limited by the DC choke / filter
High at low loads, High stress on capacitors
High Stress, requires input isolation
transformer or common mode voltage choke
High
Fast, no hardware limitations
Low, multi-step topology
No, isolation transformer and
controlled neutral point
Size
Non integrated transformer
Input choke integrated
Fully integrated
Extra space required
Standard
-
Standard
Power Electronics España S.L. © reserves the right to modify the content without prior notice