Sawtooth PWM (3-Level)
Purpose
Generate 3-level PWM signal using sawtooth carriers
Library
Control / Modulators
Description
3-level PWM generator with a sawtooth carrier. The input m is the modulation index. The switching function s outputs either 1, 0 or -1. If the modulation index is a vector the switching function is also a vector of the same width.
The block can be used to control the 3-Level IGBT Converter or the ideal 3-Level Converter. In these cases the modulation index must have a width of 3 to match the number of inverter legs.
The figures below illustrate different sampling methods offered by the modulator block. In the left figure, Natural Sampling is used. The right figure shows Regular Sampling, i.e. the modulation index is updated at the vertical flanks of the carrier. In both figures carrier signals with rising ramps are employed.
Parameters
- Sampling
- Choose between Natural and Regular Sampling.
- Ramp
- Choose between rising and falling ramps in the carrier signal.
- Carrier frequency
- The frequency
of the carrier signal, in Hz.
- Carrier offset
- The time offset of the carrier signal, in p.u. of the carrier period.
- Input limits
- The range of the modulation index. The default is [-1 1].