How do you implement space vector PWM in a three-phase inverter using a microcontroller?

1 What is SVPWM?

SVPWM is a method of controlling the output voltage and frequency of a three-phase inverter by applying pulses of different durations and phases to the switches of the inverter. SVPWM uses a reference voltage vector that rotates in a circular or hexagonal shape in the complex plane, and divides the switching period into six sectors. In each sector, the reference vector can be approximated by a combination of two adjacent active vectors and a zero vector, which correspond to different switching states of the inverter.

2 How to calculate SVPWM?

To calculate SVPWM, you need to know the magnitude and angle of the reference vector, and the switching period. The magnitude and angle can be derived from the desired output voltage and frequency, and the switching period can be chosen according to the switching frequency and the resolution of the microcontroller. Then, you need to determine which sector the reference vector belongs to, and how to distribute the switching time among the active and zero vectors. There are different formulas and methods for doing this, but one simple way is to use the symmetrical regular sampling technique, which is based on the projection of the reference vector onto the active vectors.

4 What are the advantages of SVPWM?

SVPWM has several advantages over other modulation techniques, such as sinusoidal PWM (SPWM) or third harmonic injection PWM (THIPWM). For example, SVPWM can achieve a higher output voltage and frequency, as it utilizes the maximum voltage of the DC source and the maximum switching frequency of the microcontroller. Additionally, SVPWM can reduce the harmonic distortion and total harmonic distortion (THD) of the output voltage and current, due to a minimized number of switchings and dead time between switchings. Furthermore, SVPWM can reduce the switching losses and heat dissipation of the inverter switches, by optimizing the switching sequence and duty cycle of the PWM signals.

5 What are the challenges of SVPWM?

SVPWM has a few challenges and limitations that need to be addressed. This includes requiring a higher computational power and memory capacity than SPWM or THIPWM, due to more complex calculations and operations. Additionally, SVPWM may introduce errors and inaccuracies in the output voltage and frequency due to sampling, quantization, and delay effects of the microcontroller. Furthermore, high switching frequency, resonance effect, and electromagnetic interference (EMI) effect may lead to instability and noise issues in the inverter operation.

6 Here’s what else to consider

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