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In the sinusoidal pulse width modulation, ______ wave is the reference wave signal.
Square
Triangular
Sinusoidal
All
Sinusoidal
In Sinusoidal Pulse Width Modulation (SPWM), the reference wave is a sinusoidal signal representing the desired output frequency and amplitude. This reference wave is compared with a high-frequency triangular carrier wave to determine the switching instants for the inverter power devices.
In Sinusoidal Pulse Width Modulation (SPWM), the reference wave is a sinusoidal signal representing the desired output frequency and amplitude. This reference wave is compared with a high-frequency triangular carrier wave to determine the switching instants for the inverter power devices.
maтАЛ=AcтАЛAmтАЛтАЛ тАФ Modulation index, where AmтАЛ is reference amplitude and AcтАЛ is carrier amplitude
fsтАЛ=mfтАЛ├ЧfmтАЛ тАФ Switching frequency, where mfтАЛ is frequency modulation ratio and fmтАЛ is fundamental frequency
The SPWM technique involves comparing a low-frequency sinusoidal reference signal (vrefтАЛ) with a high-frequency triangular carrier wave (vcтАЛ). When vrefтАЛ>vcтАЛ, the output of the comparator is high, and when vrefтАЛ<vcтАЛ, the output is low. The frequency of the triangular wave determines the switching frequency of the power electronic switches, while the amplitude ratio defines the modulation index.
SPWM is primarily used to control the output voltage and frequency in inverters.
The modulation index (maтАЛ) controls the fundamental output voltage magnitude.
Higher switching frequency (via mfтАЛ) pushes harmonics to higher frequencies, making filtering easier.
Reduced harmonic distortion in output voltage.
Ability to control both frequency and voltage magnitude simultaneously.
High switching losses due to high-frequency operation.
Increased complexity in control circuit design.
Variable Frequency Drives (VFDs) for induction motors.
Uninterruptible Power Supplies (UPS).
Grid-connected solar inverters.
Option B (Triangular) is the carrier wave, not the reference wave.
The fundamental frequency of the output is determined by the reference wave frequency.
C is correct тАФ The sinusoidal wave acts as the reference signal for comparison with the high-frequency triangular carrier wave in SPWM.
Always remember: in any PWM strategy, the 'Reference' sets the output shape, while the 'Carrier' sets the switching frequency and switching logic.