POWER ELECTRONICS Multi-Step VSI vs GTO CSI

Power Electronics España S.L. © reserves the right to modify the content without prior notice 01 GTO CSI – Current Source Inverter – 6 pulses – with transformer Font: High-Power Converters and ac Drives. By Bin Wu LINE UP SIDEINVERTERMOTOR 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.  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.  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 SIDEINVERTERMOTOR SIDE  Poor input power factor with SCR front end  Highly potential LC resonances  High Input harmonics, input and output filters needed.  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 conveyors, cranes, mills, …etc.)

Power Electronics España S.L. © reserves the right to modify the content without prior notice 03 VSI – Multi Step PWM modulation with low Voltage IGBt LINE UP SIDEINVERTERMOTOR 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) STORED ENERGY

Power Electronics España S.L. © reserves the right to modify the content without prior notice 04 Summary GTO-CSIVSI- Multi Step PWM Efficiency Full Power and Frequency Low Power (50%) 93% 86% 96.5% 96% Reliability Components MTBF Low, high components count 1.5 years High, low components count (Low voltage & redundant) >10 years Power Quality Harmonics Potential Resonance Power Factor 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 Motor issues Break away torque Dynamic response THDI/HVF CMV (Common Mode Voltage) 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