SVPWM Common-Mode Voltage Suppression Multiphase Motor

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Solution Overview

Problem

Current methods for suppressing common-mode voltage in multiphase motors either increase equipment size and cost, or fail to effectively reduce common-mode voltage magnitude and frequency, often at the expense of increased calculation complexity and reduced performance.

Innovation Solution

A space vector pulse width modulation (SVPWM) method that divides basic vectors into types with equal common-mode voltage magnitude, structures auxiliary vectors using an optimization model, synthesizes reference vectors, and optimizes the functioning sequence to minimize switching operations, thereby effectively suppressing common-mode voltage without increasing calculation complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If hardware methods (additional filter or structurally improved converters) are used to suppress common-mode voltage, then common-mode voltage is reduced, but equipment size and weight increase

Engineering Contradiction:

Improvecommon-mode voltageVSAvoidequipment size and weight

Core Design Contradiction:

Object-affected harmful factorsVSWeight of stationary object

Solution Approach 1:

The patent replaces hardware-based common-mode voltage suppression (filters, structural modifications) with a software-based SVPWM control algorithm. By using mathematical classification of basic vectors and optimized switching sequences, the method suppresses common-mode voltage through control strategy rather than physical components, eliminating the need for additional filters or structurally complex converters.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If current prediction algorithm is used to reduce common-mode voltage, then amplitude is reduced to 1/6 of direct current bus voltage, but calculation complexity increases and prediction accuracy decreases

Engineering Contradiction:

Improvecommon-mode voltage amplitudeVSAvoidcalculation complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent segments all basic vectors into q types based on their common-mode voltage characteristics. By classifying vectors into distinct categories with different common-mode voltage magnitudes and patterns, the algorithm can selectively choose vectors that minimize common-mode voltage while maintaining simple calculation procedures for determining switching sequences.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the approach from predicting current values to directly analyzing and selecting based on common-mode voltage parameters of basic vectors. By focusing on voltage parameter classification rather than current prediction, the method achieves effective common-mode suppression with reduced computational burden and improved accuracy.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If selected harmonics elimination PWM (SHEPWM) is used to suppress common-mode voltage, then common-mode voltage is reduced, but calculation process becomes particularly complex and difficult to implement

Engineering Contradiction:

Improvecommon-mode voltageVSAvoidimplementation difficulty

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent extracts and focuses specifically on the common-mode voltage component of basic vectors, separating it from the overall voltage analysis. By identifying and classifying basic vectors based solely on their common-mode characteristics, the method simplifies the control algorithm to only what is necessary for common-mode suppression, eliminating the complex harmonic calculation and angle searching required by SHEPWM.

Inventive Principle:

Principle #2Taking out (Extraction)

4Productivity

If quick changing of common-mode voltage occurs, then PWM switching is achieved, but electromagnetic interference and mechanical noises are produced

Engineering Contradiction:

ImprovePWM switching speedVSAvoidelectromagnetic interference and mechanical noises

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent employs periodic action by organizing basic vectors into types and using optimized switching sequences that repeat patterns designed to minimize common-mode voltage changes. The method structures the PWM switching to follow periodic patterns that reduce abrupt voltage transitions, thereby suppressing electromagnetic interference and mechanical noises while maintaining effective PWM control.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS10516361B2Space vector pulse width modulation method for suppressing common-mode voltage of multiphase motor

Publication Date: 2019.12.24 WUHAN UNIV

AI summary

A space vector pulse width modulation (SVPWM) method for suppressing a common-mode voltage of a multiphase motor includes the following steps: (1) dividing all basic vectors of the multiphase motor into q types, and selecting therefrom x types having equal common-mode voltage magnitude of which an absolute value is smallest; (2) for each type in the x types of basic vectors, structuring y classes of auxiliary vectors according to an optimization model; (3) synthesizing reference vectors by virtue of the auxiliary vectors to obtain functioning time of basic vectors functioning in each switching period; and (4) obtaining an optimal functioning sequence of the basic vectors functioning in each switching period with fewest switching operations of a converter as a purpose. The present invention may effectively suppress a magnitude and frequency of the common-mode voltage of the multiphase motor without increasing calculation complexity or reducing other performance indexes.