Analysis of Scalar PWM Approach With Optimal Common-Mode Voltage Reduction Technique for Five-Phase Inverters

Abstract

Research on Common-Mode-Voltage (CMV) reduction in multiphase drive systems has recently met an intensified interest in the available literature. This paper first explores two existing space-vector-based CMV reduction schemes for five-phase Voltage Source Inverters (VSIs), denoted as CMVR1 and CMVR2, which reduce the CMV by 40% and 80%, respectively. Moreover, a new space-vector-based CMV reduction scheme, termed as CMVR3, is proposed that not only minimizes the CMV but also reduces the overall switching losses when compared with the other schemes. The optimal duty cycles and the switching sequence of all scheme are introduced. Since the implementation of space-vector-based schemes using lookup tables is a relatively complex and time-consuming process, this paper proposes a simpler scalar PWM approach. This approach can easily be implemented using embedded PWM modules of most commercial Digital Signal Processors (DSPs). To evaluate the performance of the presented CMV reduction schemes, a detailed evaluation study is presented. The optimal CMVR scheme over the full modulation index range is also highlighted. The theoretical findings are verified using a prototype five-phase induction machine through simulations and experimentally.

A comprehensive analysis of SVPWM for a Five-phase VSI based on SiC devices applied to motor drives

“…The CMV in motor applications can cause bearing currents that lead to bearing failures, electromagnetic interference (EMI), damage to the winding insulation, and mechanical vibration. Table I shows the CMV generated for each of the different space vectors [11], [25]. Applying the Fast Fourier Transform (FFT) to the CMV signal, and the sum of the all the components of the FFT spectrum squared and divided between the half of the dc bus Vdc, we can obtain the normalized energy analysis of the CMV.…”

Simplified implementation of SVPWM techniques for a six‐phase machine with reduced current distortion features

“…where t i − 1 ≤ t ≤ t i subscript i represents the subinterval during which applied voltage vector is applied. The generalised (10) for harmonic flux (Δλ) during each subinterval i where i ∈ I, II, …, N and N is the total number of segment [23]…”

“…However, in bus clamping sequences, the switching losses are strongly influenced both by switching sequence and machine power factor [30]. The normalised per-phase switching loss for a constant dc link voltage and average switching frequency can be evaluated by [23,30]…”

“…The generalised (10) for harmonic flux during each subinterval i where and N is the total number of segment [23] where and are the duty cycle and voltage vector of m th interval, respectively. The obtained values are normalised using (11).…”

“…The multi-level carrier based PWM fed openend six-phase symmetrical and asymmetrical winding configuration winding configuration is discussed in [12,22]. The SVPWM technique to reduce the common mode voltage in multiphase machine is discussed in [23][24][25].…”