Brushless Motor Control via Space Vector Modulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electronically commutated synchronous machines face challenges in achieving improved electromagnetic compatibility due to switching effects in the converter, which generate conducted interference, affecting the reliability of electronic circuits, especially in high-power applications.
Innovation Solution
Implementing a space vector modulation method that includes applying zero vectors during the switch-off time, where all switches are connected to either the upper or lower supply voltage, with the selection based on the phase winding with the greatest absolute deviation from the mean modulation level, and adjusting the switch-off time using quasi-random values, particularly for slow-rotating or stationary motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional PWM switching is used to control phase windings, then the motor can be operated at various speeds, but switching effects generate conducted interference that affects electromagnetic compatibility
Solution Approach 1:
The patent applies periodic action by using space vector modulation with zero vectors applied at the beginning and end of each PWM period. This periodic structure with fixed switching edges reduces the frequency spectrum of emitted interference pulses compared to conventional PWM, thereby improving electromagnetic compatibility while maintaining speed control capability
Solution Approach 2:
The patent changes the switching parameter configuration by selectively connecting phase windings to either upper or lower supply voltage based on modulation level thresholds. This parameter change approach, where switching decisions are based on comparing modulation levels against thresholds, reduces the number of switching transitions and minimizes interference pulse emissions
2Object-affected harmful factors
If the number of switching processes is reduced to minimize interference, then electromagnetic compatibility improves, but the control precision and responsiveness may deteriorate
Solution Approach 1:
The patent maintains control precision by dynamically adjusting switching parameters based on modulation level thresholds. By comparing each phase's modulation level against thresholds and selectively applying zero vectors, the system achieves precise voltage control with fewer switching transitions, thus maintaining responsiveness while reducing interference
Solution Approach 2:
The patent replaces conventional PWM switching mechanics with space vector modulation that uses zero vectors at period boundaries. This substitution changes the switching pattern from edge-centered to center-centered modulation, reducing switching frequency content while maintaining effective voltage application to phase windings
Data Source
Figure 1
AI summary
The invention relates to a method for operating an electronically commutated synchronous machine, which comprises a stator having at least two, in particular three, phase windings and a rotor having at least one permanent magnet, wherein a control factor is determined periodically for each individual phase winding, and the time periods during which an upper and a lower supply voltage is applied to said phase winding via switches of an actuation circuit which are assigned to the phase winding are determined on the basis of said control factor. In accordance with the invention, the electronically commutated synchronous machine is actuated according to a method for space vector modulation, in which zero vectors are applied to the phase windings at the beginning and/or at the end of a period for a switch-off duration, wherein in each case either all of the switches connected to the upper supply voltage or all of the switches connected to the lower supply voltage are on, and wherein the selection of the zero vector, i.e. whether the conductive connection to the upper or the lower supply voltage is produced, is performed in accordance with the phase winding with the greatest, in magnitude, deviation from the average control factor, which expediently corresponds to the average of the upper supply voltage and the lower supply voltage. In addition, the invention relates to an actuation circuit and the use thereof.