Govt. Exams
Entrance Exams
Ambient temperature affects thermal behavior but does not directly cause harmonic distortion. Harmonics arise from non-linear switching, circuit inductances, and device mismatches.
Resonant converters achieve zero-voltage or zero-current switching, significantly reducing switching losses and electromagnetic interference compared to PWM converters
If dv/dt exceeds the rated value, capacitive current through the junction can turn on the thyristor prematurely, causing malfunction
Modern power MOSFETs in well-designed switching converters achieve efficiency in the range of 90-98%, depending on operating point and circuit design
Modern IGBTs have turn-off times in the range of 100-500 nanoseconds depending on the device rating and switching conditions
In a three-phase full converter, each thyristor conducts for 120° (π/3 radians) regardless of the firing angle within the commutation period
SVPWM provides superior harmonic performance, higher DC link utilization (~15% more), and better efficiency in high-power applications compared to SPWM
The output fundamental frequency is typically half the switching frequency in standard PWM, or determined by reference signal. With modulation, output frequency follows the reference signal, typically much lower than switching frequency.
CSI uses an inductor in the DC link to maintain a relatively constant current source, in contrast to VSI (Voltage Source Inverter) which uses a capacitor for constant voltage.
Thermal resistance is the temperature difference per unit power dissipation: ΔT = Rθ × P. Lower thermal resistance means better heat transfer and lower junction temperature.
