Alternator Step-Up Circuit with Common-Mode Filter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing solutions for converting mechanical energy from combustion engines into electrical energy, such as high-power alternators, face issues with high costs, common-mode currents, and reduced service life due to switching operations and partial discharges, especially when operating over a wide range of speeds and powers.
Innovation Solution
An electromechanical assembly comprising a wound-rotor alternator with a regulator, a rectifier, and a step-up circuit linked by a filter, using standard recovery time diodes and pulse width modulation for efficient voltage regulation, allowing the step-up circuit to be dimensioned for a fraction of the maximum power and eliminating common-mode currents and partial discharges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an active rectifier with IGBT inverter is used to enable operation over a wide speed range, then the speed range is expanded, but the cost increases and common-mode currents are generated that affect bearing service life
Solution Approach 1:
A common-mode filter is introduced as an intermediary component between the IGBT inverter and the alternator bearings. This filter blocks common-mode currents while allowing differential-mode power transmission, thereby protecting the bearings from electrostatic discharge without limiting the wide speed range operation capability
Solution Approach 2:
The rectification function is segmented into two independent paths: an active IGBT inverter path for wide speed range operation and a passive diode bridge path for standard operation. The system can switch between paths or operate in parallel, allowing wide speed range capability without requiring the inverter to handle full power, thus reducing cost and switching losses
2Power
If an IGBT inverter is used for voltage stepping up, then the voltage can be stepped up over a wide speed range, but switching operations generate electromagnetic radiation that interferes with other electrical devices
Solution Approach 1:
An electromagnetic filter is introduced as an intermediary between the IGBT inverter and the output terminals. This filter attenuates high-frequency electromagnetic radiation and common-mode currents while maintaining efficient power transmission, thereby reducing interference with other electrical devices in the installation
3Adaptability or versatility
If a step-up chopper is used to enable operation over a wide speed range, then the speed range is expanded, but fast recovery diodes are required which are much more expensive
Solution Approach 1:
The rectification function is segmented into two independent paths: an active IGBT inverter path for wide speed range operation and a passive diode bridge path for standard operation. The system can switch between paths or operate in parallel, allowing wide speed range capability without requiring the inverter to handle full power, thus reducing cost and switching losses
4Power
If switching operations are performed to step up voltage, then the desired voltage level is achieved, but partial discharges occur that reduce the service life of the winding
Solution Approach 1:
An electromagnetic filter with appropriate capacitance values is introduced as an intermediary between the IGBT inverter and the alternator windings. This filter smooths voltage transitions and reduces high-frequency voltage spikes during switching operations, thereby minimizing partial discharges and extending winding service life
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
Enables operation over a wide range of variable speeds and powers at reduced costs, using standard diodes and minimizing the risk of common-mode currents and partial discharges, thereby extending the service life of alternator components.
Implementation Method 1
An alternator includes, in a manner known per se, a field winding, generally at the rotor, supplied with DC current either by rings and brushes or by an exciter, so as to generate an AC voltage in an armature winding, generally at the stator
Data Source
AI summary
The invention relates to an electromechanical assembly comprising: an alternator with a wound rotor; a regulator acting on the excitation of the alternator; a rectifier at the outlet of the alternator, supplying a rectified voltage to a continuous bus; and a booster circuit connected by means of a filter to the outlet of the alternator and supplying a voltage to the continuous bus.