EC Motor Commutation Noise Reduction via Gradient Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electronically commutated electrical machines using block commutation generate high noise levels due to abrupt commutation transitions, which are problematic for applications like electric vehicles where noise reduction is crucial, and existing sensorless rotor position detection methods are hindered by the need for a blanking interval.
Innovation Solution
Implementing pulse width modulation for phase voltage potentials with limited gradient transitions before and after the blanking interval, allowing for smoother commutation and eliminating the need for a blanking interval, thereby reducing noise and enabling sensorless motor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If block commutation is used to control the electrical machine, then the machine can be operated without sensors, but high noise levels are generated due to abrupt commutation transitions
Solution Approach 1:
The patent changes the voltage gradient parameter during commutation transitions. Instead of abrupt voltage switching, the controller applies voltage with limited gradient (dv/dt) to smooth the transitions. This parameter modification reduces the steepness of current changes while maintaining the block commutation structure needed for sensorless operation.
Solution Approach 2:
The patent introduces dynamic control of the commutation process by adjusting the voltage application timing and gradient. The controller dynamically modifies the voltage profile during transitions, creating a time-varying control strategy that smooths commutation while preserving the fundamental block commutation operation for sensorless control.
2Measurement precision
If a blanking interval is provided to measure induced counter-voltage for sensorless operation, then rotor position can be detected, but the abrupt commutations required create torque ripples and radial force excitations leading to noise
Solution Approach 1:
The patent modifies the voltage gradient parameter during the commutation transitions that frame the blanking interval. By limiting dv/dt, the induced counter-voltage measurements remain accurate while the resulting current changes are smoother, reducing torque ripples and noise.
Solution Approach 2:
The patent introduces an intermediary control layer between the blanking interval requirement and the commutation execution. The controller acts as an intermediary that shapes the voltage transitions to have limited gradient, mediating between the measurement requirement and noise reduction goal.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution results in significantly lower noise levels and smoother phase current curves, effectively combining noise reduction with sensorless motor operation by using pulse width modulation for phase voltage transitions.
Implementation Method 1
Multi-phase electronically commutated electrical machines, especially synchronous motors, z. B. be driven by providing a provided by a rotor excitation magnetic field leading stator magnetic field. The stator magnetic field, in particular its direction and strength, is generated by applying phase voltages to phase strands of the stator of the electrical machine.
Implementation Method 2
One possible method is to measure the counter-voltage induced in the phase strands and to determine the point in time at which it crosses zero. The point in time at which the induced reverse voltage crosses zero can be used to determine the position of the rotor (back EMF method).
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method for operating an electronically commutated electric machine (2). Alternating phase voltage potentials are applied to the phase conductors of the electric machine (2) for commutation, said phase voltage potentials being generated by a pulse-width modulation so that the height of the applied phase voltage potential is determined by a duty cycle (TV) of the pulse width modulation. In order to determine an instant of a zero crossing of a current induced in a phase conductor, a blanking interval (AT) which represents a time slot, is provided, when no phase current potential is applied to the corresponding phase conductor. A first transition time slot (ÜT1) is provided prior to and/or after the blanking interval (AT) during which the progression of the applied phase voltage potential has a defined first gradient during.