Download 1. Influence Mechanism Analysis of voltage sags on chargers

Study on impact of Voltage sags on Different Types of
Electric-Vehicle Chargers
Songhui,Xuyonghai
North China Electric Power University
Abstract:
The impact of voltage sags on large-scale electric vehicle charging can not be ignored , but the problem
has not been once paid attention to. PSCAD software is used to analysis of the impact of voltage sag on the
different types of charger . The simulation results show that the impact of voltage sags on charger is not only
related to the strength and type of voltage sag,but also related to the working state of the charger.
1.
Influence Mechanism Analysis of voltage sags on chargers
Charger is mainly composed of a AC-DC converter and DC-DC converter . Within a certain input
voltage range, charger output voltage is maintained constant, when a certain depth voltage sag occurs,
the charger output voltage will drop so that it does not work properly.
2.
Modeling of charger and simulation analysis
PSCAD software is used in modeling of single-phase on-board charger ,three-phase 6-pulse
uncontrolled rectifier, 12-pulse uncontrolled rectifier and pulse width modulation rectifier .
Simulation is used to analyse the impact of different severity and different types of voltage sag on
charger working in different conditions and the degree of influence was assessed.
Simulation is used to analyse the influence of sag characteristics including voltage sag magnitude,
duration, phase-angle jump and point-on-wave of sag initiation on the charger; Being different With
on-board charger with single-phase power supply , the other three kind of chargers adopts three-phase
mode of power supply, need simulation to analyse the influence of a single-phase, two-phase and
three-phase voltage sag on charger respectively; When voltage sag happens, battery charging method
the size of output current and voltage and other factors may have effects on the ability of charger to
deal with voltage sag, simulation is used to analyse the ability of charger working in different
conditions to deal with voltage sag.
3.
Conclusion
(1)The magnitude and duration of voltage sags is the main factors which affect the normal
operation of charger.
(2)In three-phase rectifier charger, the impact of three-phase voltage sag on charger is the most
serious, followed by the two-phase voltage sag, single-phase voltage sag lmost has no influence on the
charger.
(3) When voltage sag happens, if the output voltage of the charger AC-DC converter was
significantly greater than the voltage output of DC-DC converter, then chargers has a better ability to
deal with voltage sags.
(4)Single-phase on-board charger has a better ability to deal with voltage sags. In three-phase
rectifier charger, the PWM rectifier charger has the strongest ability to cope with voltage sags,
followed by 12-pulse rectifier charger, 6-pulse rectifier machine is worst.
Keywords:
voltage sag; Electric-Vehicle Chargers;PSCAD;Rectifier
Author’s brief introduction and contact information:
Song Hui, male, born in 1990, master's degree, research direction for Voltage Sag Analysis and
electric vehicle charging, etc..
Xu Yonghai, male, born in 1966, Professor, doctoral tutor, research direction for the power quality
analysis and control, new energy power systems, etc..