GATE Electrical Engineering - Complete Master Library

 

Page 42 – Space Vector PWM (SVPWM)

Subject: Power Electronics
Topic: Space Vector Pulse Width Modulation
Level: GATE / PSU Advanced Concept

                                           

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🔹 Why SVPWM?

SVPWM provides better DC bus utilization compared to SPWM. It increases maximum output voltage by about 15%.

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🔹 Basic Concept

• Three phase voltages represented as a single rotating vector
• Space vector rotates in α-β plane
• Inverter has 8 switching states
• 6 active vectors + 2 zero vectors

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🔹 Voltage Vector Equation

V_ref = (2/3) (V_a + aV_b + a²V_c)

Where:

• a = e^(j120°)
• Represents space vector transformation

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🔹 Maximum Output Voltage

SPWM: V_LL,max = 0.866 V_dc
SVPWM: V_LL,max = V_dc

👉 15% higher voltage utilization.

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🔹 Sector Division

• 360° divided into 6 sectors
• Each sector = 60°
• Reference vector synthesized using two adjacent active vectors

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🔹 Switching Time Calculation

T₁ = T_s (V_ref/V_dc) sin(60° − α)
T₂ = T_s (V_ref/V_dc) sin(α)

Where:

• T_s = switching period
• α = angle inside sector

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🔹 Advantages

• Better DC bus utilization
• Lower harmonic distortion
• Reduced switching losses
• Used in high-performance motor drives

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📌 Quick Revision

6 active vectors + 2 zero vectors
6 sectors (60° each)
15% higher voltage than SPWM

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Power Electronics Advanced Series – Shaktimatha Learning