Switched Reluctance Motor Starting Method
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Solution Overview
Problem
The existing methods for starting switched reluctance motors are inefficient, with long starting durations and high current demands, which can lead to coil deterioration and imbalance.
Innovation Solution
The method involves simultaneously energizing two pairs of stator coils to quickly settle the rotor in its starting position, balancing the current load and reducing coil stress, and then turning off one pair while keeping the other energized to continue rotation, with subsequent pairs being turned on and off at constant frequencies to accelerate the motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If one pair of stator coils is energized to start the motor, then the motor can be started, but the starting time is long and current demand is high
Solution Approach 1:
The starting process is divided into two distinct phases: first phase energizes one pair of coils to initiate rotation and settle the rotor, second phase energizes a different pair of coils to accelerate the motor to operational speed. This segmentation allows optimization of each phase independently, reducing overall starting time while limiting current exposure duration for any single coil pair.
Solution Approach 2:
The motor starting employs periodic energization of different coil pairs in sequence. The first pair is energized for a limited initial period to start rotation, then turned off and replaced by a second pair for acceleration. This periodic switching prevents continuous high current exposure of any single coil pair, thereby extending lifespan while achieving rapid starting through cumulative acceleration.
2Productivity
If high current is applied to start the motor quickly, then starting time is reduced, but coil deterioration and imbalance occur
Solution Approach 1:
The high current demand is segmented across two different coil pairs rather than concentrating it on one pair. The first pair handles the initial starting current, then is replaced by the second pair for acceleration current. This segmentation distributes the thermal and electrical stress, preventing deterioration and imbalance in any single coil pair while maintaining high starting performance.
3Reliability
If multiple pairs of coils are energized simultaneously, then current load is balanced, but the motor complexity increases
Solution Approach 1:
Instead of energizing multiple coil pairs simultaneously which would balance current but increase complexity, the solution segments the energization into sequential phases with only one or two pairs active at any given time. This reduces the instantaneous control complexity while still achieving current load balancing across the motor's operational cycle through the phased approach.
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 reduces starting time, balances current load, and extends the lifespan of the coils by minimizing high current demands, allowing for efficient and balanced operation.
Implementation Method 1
energising pairs of stator coils in turn to draw the poles of the rotor forward
Implementation Method 2
Positions of the rotor in which a pair of diametrically opposite poles of the rotor are aligned along the diameter between the energised pair of stator poles are positions of the rotor that have minimum reluctance for the magnetic circuit
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
An improved method of starting a switched reluctance motor uses two neighbouring pairs of coils, both energised, to bring the rotor to its initial position. Then one of pairs of coils is turned off and the rotor is attracted by the other pair of coils to give it an initial rotational speed. An intermediate stage uses just one pair of coils of the motor to bring it up to operational speeds, after which the normal cycling of all the coils can be used.