PWM Gate Signal Generator (Three-phase, Two-level)
Generate six switch-controlling pulses for three-phase, two-level gating switching devices
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The PWM Gate Signal Generator (Three-phase, Two-level) block controls switching behavior for a three-phase, two-level power converter. The block uses the gating times provided as inputs to generate six switch-controlling pulses. You can obtain the gating time information using the PWM Timing and Waveform Generator (Three-phase, Two-level) block.
This block allows you to choose natural, symmetric, or asymmetric sampling of the modulation wave.
The PWM Gate Signal Generator (Three-phase, Two-level) block does not perform carrier-based pulse width modulation (PWM). Instead, the block uses the gating times to generate both the switch-controlling pulses and the modulation waveforms that the block outputs.
Carrier-based PWM is, however, useful for showing how the sampling mode that you select relates to the switch-on and switch-off behavior of the pulses that the block generates. A generator that uses a three-level, carrier-based PWM method:
Samples a reference wave
Compares the sample to two parallel triangle carrier waves, separated by one level
Generates a switch-on pulse if a sample is higher than the carrier signal or a switch-off pulse if a sample is lower than the carrier wave
To determine switch-on and switch-off pulse behavior, a three-level carrier-based PWM generator uses these methods to sample each of the triangle waves:
Natural — The sampling and comparison occur at the intersection points of the modulation wave and the carrier wave.
Asymmetric — Sampling occurs at the upper and lower boundaries of the carrier wave. The comparison occurs at the intersection that follows the sampling.
Symmetric — Sampling occurs only at the upper boundary of the carrier wave. The comparison occurs at the intersection that follows the sampling.
TgabcON — Switch-on gating time
Switch-on gating time, specified as a vector of three elements, with one element for each phase.
TgabcOFF — Switch-off gating time
Switch-off gating time, specified as a vector of three elements, with one element for each phase.
g — Gate control
Six pulse waveforms that determine switching behavior in the attached power converter, returned as a vector.
Sampling mode — Wave-sampling method
Natural (default) |
Wave-sampling method. The sampling mode determines whether the block samples the modulation waveform when the waves intersect or when the carrier wave is at one or both of its boundary conditions.
Switching frequency (Hz) — Switching rate
1e3 (default) | positive scalar
Rate at which the switches in the power converter switch.
Sample time (s) — Block sample time
5e-5 (default) | positive scalar
Time interval between successive block executions. To ensure adequate resolution in the
generated signal, set this value to be less than or equal to
where Fsw is the
Switching frequency (Hz).
 Chung, D. W., J. S. Kim, and S. K. Sul. “Unified Voltage Modulation Technique for Real Time Three-Phase Power Conversion.” IEEE Transactions on Industry Applications, Vol. 34, No. 2, 1998, pp. 374–380.
 Seo, J. H., C. H. Choi, and D. S. Hyun. “A new simplified space-vector PWM method for three-level inverters.” IEEE Transactions on Power Electronics, Vol. 16, No. 4, 2001, pp. 545-550.