Waveform Description - Xilinx Spartan 6 FPGA Quick Start Manual

Qdesys Sensorless Field Oriented Control Quick Start Guide

Waveform Description

Left Side (from the top):
3-phase voltages: These are the voltage waveforms delivered to each of the motor phases
(windings) by the half-bridges on the FMC. The hardware does not actually sample these
voltages, so instead they are simulated in software based on the measured current.
2 sampled currents: The current is sampled in two of the phases. The 3
calculated using Kirchoff's Current Law (they all must sum to zero). The 3
displayed. The currents are filtered with a low-pass response in order to attenuate the switching
noise. The user can set the filter cutoff value. Later in the demo you will be instructed to set it to
~10kHz.
Active power: This is just as the name implies – the active power being delivered to the motor.
With the radio buttons, you may also display reactive power and total power.
Vs/Is: This graph plots the angle of the Voltage against the angle of the current.
Right Side (from the top):
Vs X/Y Plot: This graphs plots the X/Y components of the Vs vector on a single Cartesian
plane.
Remember that we take the three phase currents and use the Clarke transform to create 2.
Therefore we have 2 current vectors and two voltage vectors. Think of this plot as a Real vs.
Imaginary graph.
Is X/Y Plot: This graph plots the X/Y components of the Is vector on a single Cartesian plane.
Vs/Is: This shows the actual voltage, and current vectors. If we had an encoder connected, it
would also display the position of the rotor relative to these two parameters.
In the waveform plots you may notice a large amount of noise coming from the PWM switching
activity. Next we will apply a lower cutoff frequency to the low-pass filters in order to attenuate
the noise.
14. In the Motor 0 Main Panel window top menu, select Advanced FOC Control
15. In the FOC Control Panel, change the Current Filter cutoff frequency Fcut_1 to 10kHz as shown
below. Be sure to click the Enter button before closing this window.
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