Dual Rotor Electrical Machine Field Position Control Without Stepping
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Solution Overview
Problem
Dual rotor electrical machines face challenges in accurately determining the virtual position of the stator electromagnetic field due to stepping effects caused by decimal fractions in angular position calculations, which complicates control and alignment with the rotor and modulator fields.
Innovation Solution
A system with a controller that calculates the virtual position of the stator electromagnetic field as a weighted sum of the inner rotor and modulator angular positions, using specific weights based on the number of permanent magnet pole pairs and modulating segments, and adjusts for position offsets to synchronize the fields, thereby eliminating stepping effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a weighted sum calculation is used to determine the virtual position of the stator electromagnetic field, then the control precision and field synchronization are improved, but stepping effects occur due to decimal fractions in the angular position calculations
Solution Approach 1:
The patent segments the dual rotor electrical machine into distinct components (inner rotor with permanent magnets, outer rotor with modulation segments, and stator) and uses separate position resolvers for each rotor. This segmentation allows independent measurement of angular positions, which are then combined through weighted sum calculation to determine the virtual stator field position, improving measurement precision while managing stepping effects through proper weighting based on pole-pair numbers.
Solution Approach 2:
The patent introduces a virtual electromagnetic field position as an intermediary concept that mediates between the actual positions of the inner and outer rotors. The controller calculates this virtual position using a weighted sum formula where weights are determined by the pole-pair numbers of each rotor. This intermediary virtual position enables precise control of the stator electromagnetic field without directly commanding the physical rotors, thereby reducing stepping effects while maintaining high control precision.
2Measurement precision
If the virtual position is calculated using decimal fractions from position resolvers, then the angular position accuracy is improved, but the stepping effect complicates control and alignment
Solution Approach 1:
The patent changes the parameters used in the position calculation by introducing weights based on the pole-pair numbers of the inner and outer rotors. Instead of directly using the decimal fraction outputs from position resolvers, the controller applies a weighted sum formula: Theta_Stator = (n1 * Theta_Rotor1 + n3 * Theta_Rotor3) / (n1 + n3), where n1 and n3 are the pole-pair numbers. This parameter transformation maintains angular position accuracy while eliminating stepping effects in the control calculations.
3Measurement precision
If two position resolvers are used to obtain angular positions of inner rotor and modulator, then the field position determination accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent makes the position resolvers universal by using the same type of resolver for both the inner rotor and outer rotor measurements. Both resolvers output angular positions in the same format, which can be directly combined through the weighted sum calculation. This universal approach improves field position determination accuracy while minimizing device complexity by avoiding the need for different sensing mechanisms for each rotor.
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 solution enables precise control and synchronization of the electromagnetic fields, improving operational stability and reducing stepping effects, allowing the dual rotor electrical machine to operate effectively in speed and torque modes.
Implementation Method 1
determine a virtual position of an electromagnetic field of the stator based on a weighted sum of an angular position of the inner rotor and an angular position of the modulator
Data Source
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AI summary
A system comprises a dual rotor electrical machine (310) including a stator (330), an inner rotor (380) including a first number of permanent magnet pole pairs (370a, 370b), and a modulator (390) including a second number of modulating segments (360), and a controller configured to execute non-transitory machine readable instructions that, when executed by the controller, cause the system to determine a virtual position of an electromagnetic field of the stator (330) based on a weighted sum of an angular position of the inner rotor (380) and an angular position of the modulator (390), wherein weights in the weighted sum are based on the first number and the second number.