In optimizing the harmonic performance of the output voltage

synchronized space vector pulse width modulation (SVPWM) can be adopted in the low carrier ratio (Cr) condition of the high-power traction inverter. In this article

the three-level active neutral point clamped (3L-ANPC) inverter used for 600 km/h high-speed maglev is taken as the research object. Under the integer multiple Cr of three

to achieve synchronization

phase voltage symmetry

and avoid two-level jump (TLJ)

this paper proposes four sector division methods and four sampling point setting methods. Subsequently

a PWM sampling method at a specific angle based on the multi-sampling rate control system is provided. Accordingly

the synchronized SVPWM of the half-period pulse number of any phase voltage can be realized

and it can be transited to the single-pulse overmodulation region. To analyze the harmonic characteristics

this paper proposes the phase voltage spectrum analysis method of the three-level inverter under SVPWM by using the double Fourier transform. According to the proposed strategies

the carrier change and the execution of the switching sequence during the switching between the modulation methods under different Cr are analyzed

and then a switching strategy is proposed. The experimental results show that the proposed synchronized SVPWM strategy can satisfy the three-phase symmetry (TPS)

half-wave symmetry (HWS)

and quarter-wave symmetry (QWS)

and smooth switching between the two modulation strategies without TLJ and obvious current fluctuation can be realized.