EC Motor Torque Ripple Reduction via Magnetic Energy Storage
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Solution Overview
Problem
Existing EC motors with single-phase feed and power factor correction (PFC) face challenges in reducing torque ripple and noise due to pulsating DC voltage, which is exacerbated by the need for large electrolytic capacitors that increase manufacturing costs.
Innovation Solution
The method involves storing electrical energy as magnetic energy in the motor windings by adjusting the id current trajectory using a dynamic, flatness-based, non-linear regulation in the state space, allowing the capacitance of the PFC capacitor to be undersized, thereby reducing the pulsation of the DC voltage and minimizing torque ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a sufficiently dimensioned electrolytic capacitor is used in the link circuit to achieve sinusoidal power supply current, then power factor correction is improved, but manufacturing costs increase and the capacitor occupies more space
Solution Approach 1:
The patent extracts the energy storage function from the electrolytic capacitor in the link circuit, allowing the capacitor to be significantly reduced or omitted. The motor's own windings take over part of the energy storage function, enabling the system to operate with minimal or no external capacitors while maintaining acceptable power factor correction performance
Solution Approach 2:
The motor windings serve multiple functions: they act as both the motor's functional components and as energy storage elements. This multi-functionality eliminates the need for separate large electrolytic capacitors, reducing both cost and component count while maintaining system performance
2Ease of manufacture
If the capacitance of the link circuit capacitor is reduced to lower costs, then manufacturing costs decrease, but torque ripple increases due to pulsating DC voltage
Solution Approach 1:
The patent converts the harmful pulsating DC voltage (which would normally cause torque ripple) into a beneficial control opportunity. By deliberately allowing the pulsating voltage and using it to modulate the d-axis current, the system transforms what was a harmful effect into a useful control mechanism for maintaining constant torque
Solution Approach 2:
The patent changes the d-axis current parameter dynamically in response to the pulsating DC voltage. By adjusting the d-axis current trajectory based on the voltage pulsations, the system compensates for the reduced capacitance effect and maintains constant torque output, thereby eliminating torque ripple despite using minimal or no capacitors
3Ease of manufacture
If a pulsating DC voltage is used to reduce capacitor size, then manufacturing costs and component count decrease, but current harmonics and losses increase
Solution Approach 1:
The patent implements feedback control where the pulsating DC voltage is detected and used to adjust the d-axis current in real-time. This closed-loop control ensures that the motor operates efficiently despite the pulsating voltage, minimizing energy losses by dynamically compensating for the voltage variations through current modulation
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
This approach effectively compensates for undesirable torque pulsation by controlling the id current, reducing noise and maintaining constant motor torque while minimizing losses and manufacturing costs.
Implementation Method 1
buffer-storing electrical energy in the EC motor (1) which is embodied with a power factor correction circuit (PFC) having a capacitor at the power supply system input for a specific power supply system AC voltage UN
Data Source
AI summary
The disclosure relates to a method for reducing the torque ripple and noise evolution in an EC motor with single-phase feed by buffer-storing electrical energy in the EC motor, which is embodied with a power factor correction circuit (PFC) having a capacitor (Cz) at the power supply system input for a specific power supply system AC voltage UN, wherein the capacitance of the capacitor is dimensioned such that when the power supply system AC voltage UN is applied, a pulsating DC voltage is generated in a link circuit (Z), wherein the pulsating electrical energy generated as a result is stored by means of a primary regulation of the id current component as magnetic energy in the EC motor at least for a predefined time period.