Variable Lead Angle Control for Polyphase Motor Torque Optimization
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Solution Overview
Problem
Conventional control techniques for polyphase machines are inadequate in achieving optimal torque versus speed characteristics during motoring and generating, leading to issues such as overstressed mechanical linkages, excessive engine start times, high power losses, electromagnetic interference, and inefficient battery usage.
Innovation Solution
The method involves commutating windings of a polyphase machine in response to commutation control signals, automatically varying the lead angle between electromagnetic fields of stator and rotor phases as a function of rotational speed to optimize torque production, and monitoring the angular position of the rotor to produce desirable torque versus speed characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the polyphase machine is optimized as a generator, then generating performance is improved, but motoring torque-speed characteristics deteriorate
Solution Approach 1:
The patent applies dynamics by making the lead angle variable rather than fixed. The controller dynamically adjusts the lead angle between stator and rotor electromagnetic fields based on operating conditions (motoring vs. generating mode). This allows the system to optimize performance for both motoring and generating operations without being constrained by a fixed design optimization, directly resolving the contradiction between generating performance and motoring characteristics.
Solution Approach 2:
The patent changes the parameter of lead angle from a fixed value to a variable parameter that can be adjusted based on operational mode. By modifying this electromagnetic parameter dynamically, the system achieves optimal torque-speed characteristics in motoring mode while maintaining generating performance, eliminating the need to choose between the two operational modes.
2Device complexity
If a fixed lead angle is used, then control simplicity is improved, but torque production efficiency deteriorates
Solution Approach 1:
The system transitions from a static fixed lead angle to a dynamic variable lead angle controlled by a controller that monitors operating conditions. This dynamic adjustment optimizes torque production efficiency across different speed and load conditions while maintaining reasonable control complexity through automated control algorithms.
Solution Approach 2:
The controller uses feedback from speed sensors and operational mode detection to automatically adjust the lead angle. This closed-loop control ensures optimal torque production efficiency is maintained across varying operating conditions without requiring manual intervention or complex mechanical adjustments.
3Loss of time
If peak torque is increased at ignition speed, then engine start time is reduced, but mechanical linkages are overstressed
Solution Approach 1:
The variable lead angle control enables dynamic optimization of the torque curve shape. The controller can produce high peak torque at ignition speed for rapid engine starting while simultaneously controlling the overall torque profile to prevent excessive stress on mechanical linkages. This is achieved by adjusting the lead angle to shape the torque-speed characteristic appropriately for each operating phase.
Solution Approach 2:
By changing the lead angle parameter, the system modifies the electromagnetic torque characteristics to achieve a torque profile that provides sufficient peak torque for rapid starting while maintaining acceptable stress levels on mechanical components throughout the acceleration range.
4Device complexity
If conventional control techniques are used, then implementation simplicity is improved, but power losses and electromagnetic interference increase
Solution Approach 1:
The controller implements feedback-based commutation control that monitors rotor position and speed to optimize switching timing and current waveforms. This reduces power losses by minimizing resistive heating and reduces electromagnetic interference through optimized commutation sequences, while maintaining reasonable implementation complexity through standard control techniques.
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 enhances torque production, reduces power losses, minimizes mechanical stress, and optimizes battery usage, achieving improved efficiency and reduced costs by allowing for more flexible and efficient control of polyphase machines during both motoring and generating operations.
Implementation Method 1
Polyphase machines, such as permanent magnet machines, synchronous machines, and wound rotor machines must be driven such that the windings thereof are energized as a function of the rotor position (and, thus, the rotor flux) in order to obtain driving torque from the machine
Data Source
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AI summary
Methods and apparatus provide for commutating windings of a polyphase machine such that electromagnetic fields of stator and rotor phases of the polyphase machine produce at least one of motoring and generating torque, wherein the controller is operable to automatically vary at least one of a lead angle measured between the electromagnetic fields of the stator and rotor phases and rotor excitation parameters as a function of a rotational speed of the polyphase machine.