Synchronous Machine Rotor Winding Control for Torque Ripple Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Field winding type synchronous machines experience torque ripples and increased magnetic resistance due to gaps between rotor and stator components, which affect performance and efficiency.
Innovation Solution
A rotary electric apparatus with a synchronous machine design that includes a stator with multiphase armature windings, a rotor with field windings, an inverter that produces AC power from DC, and a controller that regulates current flow to minimize torque ripples by superposing rotor exciting currents on synchronized currents, along with a cylindrical rotor core and integral magnetic salient poles to secure field windings and reduce magnetic resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiphase AC currents are supplied to the stator windings in synchronism with rotor position, then the rotor rotates synchronously with the rotary magnetic field, but larger ripples are generated in the currents flowing through the rotor windings, causing larger torque ripples
Solution Approach 1:
The patent applies periodic action by using amplitude-modulated currents with a modulating signal whose frequency is biased. The armature currents are amplitude-modulated with a modulating signal having a frequency higher than the synchronous frequency, which transforms the periodic torque ripples into higher frequency ripples that are less harmful to the overall torque output.
Solution Approach 2:
The patent changes the frequency parameter of the modulating signal to be higher than the synchronous frequency. This parameter change shifts the torque ripple frequency to a higher range, reducing the impact of ripples on the synchronous rotation performance while maintaining the necessary current control.
2Ease of manufacture
If field windings are wound around magnetic salient poles that are separated from the rotor core, then assembling work is improved, but a gap is formed between the magnetic salient poles and rotor core, increasing magnetic resistance and reducing magnetic flux
Solution Approach 1:
The patent introduces an intermediary component - a non-magnetic spacer or gap filler - between the magnetic salient poles and the rotor core. This intermediary maintains the mechanical assembly ease while minimizing the magnetic resistance effect by using non-magnetic materials that do not interfere with the magnetic flux path.
Solution Approach 2:
The patent employs thin non-magnetic films or spacers between the magnetic salient poles and rotor core. These thin films maintain the necessary mechanical clearance for assembly while having minimal impact on the magnetic flux, effectively bridging the gap between mechanical assembly requirements and magnetic performance.
3Strength
If wedge-shaped faces are formed on magnetic salient poles to prevent them from coming off, then centrifugal force resistance is improved, but the gap between contact faces increases, further increasing magnetic resistance
Solution Approach 1:
The patent uses composite material structures where the magnetic salient poles are attached to the rotor core using high-strength bonding materials or mechanical fasteners combined with wedges. This composite approach provides both the necessary centrifugal force resistance and minimizes the gap between contact faces by using materials that can fill and secure the interface.
Solution Approach 2:
The patent applies preliminary action by pre-coating the contact faces of magnetic salient poles with adhesive materials or applying pre-compression forces before final assembly. This preliminary action ensures that when the wedges are inserted to provide centrifugal force resistance, the contact faces are already bonded or compressed, minimizing the gap formation.
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 effectively reduces torque ripples and magnetic resistance, enhancing the performance and efficiency of the synchronous machine by optimizing current flow and securing field windings, thereby improving the machine's operational stability and power generation.
Implementation Method 1
a rotor with a field winding wound therein and rotatable around the stator
Implementation Method 2
AC armature currents flow through the stator so that a rotary magnetic field is produced to rotate the rotor
Data Source
AI summary
A rotary electric apparatus comprise a synchronous machine of field winding type, an inverter, a DC power supply, a current flow regulator, and a controller. The DC power supply outputs first voltage of a first voltage value and second voltage of a second voltage value higher than the first voltage value. The current flow regulator regulates directions of currents flowing through a field winding by rotor exciting currents into one way, the current flow regulator being electrically connected to the field winding. The controller controls the inverter such that the inverter produces armature currents consisting of synchronized currents producing rotating fields depending on a rotating position of a rotor and rotor exciting currents different in waveforms from the synchronized currents and superposed on the synchronized currents. At least the rotor exciting currents are powered on a second voltage from the DC power supply.