Synchronized Sine-triangle PWM Based Control of High-Speed PMSM Drive With Reduced Switching Losses and Enhanced Performance

Permanent magnet synchronous motors (PMSM), rated at high fundamental frequencies
$(\geq 500{\text{Hz}})$
, are gaining attention in propulsion applications due to high power density, high efficiency, light weight and compact size. In order to ensure reasonable line current THD
$(I_{THD})$
and torque ripple, the ratio of switching
$(f_{sw})$
and fundamental
$(f_{1})$
frequencies (i.e. pulse number) is kept high. However, due to high switching energy losses, maximum
$f_{sw}$
is restricted. Typically, such motor drives are operated with asynchronous sine-triangle (AST) pulse width modulation (PWM) with maximum
$f_{sw}$
restricted below 10kHz. This paper proposes synchronized sine-triangle (SST) based PWM technique which reduces the switching energy losses and
$I_{THD}$
significantly compared to AST PWM. Further, four different orientations for carrier wave are analyzed and compared in terms of
$I_{THD}$
to identify the best orientation. Simulation results pertaining to 3-phase 5500rpm and 50kW PMSM drive are presented to validate the findings.