Sinusoidal Measurement (PLL, Three-Phase) Block Outputs Zero Magnitude (Mag = 0)

I'm using the Sinusoidal Measurement (PLL, Three-Phase) block in Simulink to measure frequency, angle, and magnitude from a 3-phase signal created using three Sine Wave blocks (50 Hz, 325 V peak, phases 0, 2π/3, 4π/3). These signals are connected via a Mux block (as a 3×1 vector) to the abc input of the PLL.

I observe:

• Frequency output = 50 Hz ✅
• Angle output = ramps from 0 to 2π ✅
• Magnitude output = always zero (0) ❌

I tried:

• Delaying the signal using a Switch block to avoid flat start (signal connects after 0.05 s)
• Changing PLL loop filter gains and initial frequency
• Checking signal shape in Scope (sine waves appear correct)

Still, the Mag output remains zero.

How can I resolve this and get the correct magnitude output?

Thanks in advance for your help!

Answer 1

[Yoshi Minagawa]

Hi Nanda,

I'm not very familiar with this field, but after changing the phase value of the sine wave block and adjusting the gain and sample time of the Sinusoidal Measurement (PLL, Three-Phase) block, I was able to estimate the frequency and magnitude without any issues.

I've attached the modified model for your review. Please take a look.