Switched Reluctance Machine Control via Periodic Energization
Solution Overview
Problem
Conventional switched reluctance machines require precise timing of phase energization with respect to rotor position for efficient operation, which is challenging at varying speeds and can lead to high switching frequencies, reducing efficiency.
Innovation Solution
The method involves initiating phase windings energization in a predetermined sequence, allowing for consecutive inductance cycles with no energization, thereby increasing the interval for flux growth and decay, and reducing the overall switching frequency by adjusting the rate of energization to match or be less than the rate of rotor pole alignment with stator poles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precise timing of phase energization is implemented to match rotor position, then machine efficiency is improved, but switching frequency increases which reduces overall system efficiency
Solution Approach 1:
The patent applies periodic action by allowing consecutive inductance cycles with no energization, creating a periodic pattern where energization occurs only at specific intervals rather than continuously. This reduces the switching frequency while maintaining the necessary flux growth and decay cycles for machine operation, thereby reducing switching losses while preserving machine efficiency.
2Measurement precision
If phase energization is initiated at every inductance cycle, then flux control precision is improved, but switching frequency increases reducing system efficiency
Solution Approach 1:
The patent applies partial action by initiating energization only at selected inductance cycles rather than every cycle. This allows the system to achieve sufficient flux control precision through selective energization events, while avoiding the excessive switching that would reduce system efficiency. The partial energization strategy maintains adequate flux control while improving overall productivity.
3Loss of energy
If switching frequency is reduced by skipping energization cycles, then switching losses are reduced, but flux growth and decay intervals are shortened
Solution Approach 1:
The patent applies dynamics by adaptively adjusting the energization strategy based on operating conditions. The system dynamically selects which inductance cycles to energize, allowing flexible control of flux growth intervals. This dynamic approach enables the system to reduce switching losses by skipping certain cycles while maintaining adequate flux growth intervals when needed, optimizing the balance between energy losses and flux control.
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 extends the interval for flux growth and decay, increases machine output, and reduces switching frequency, leading to improved efficiency and reduced losses in the drive system, allowing for stable operation at lower speeds and higher speeds with relaxed switching burdens.
Implementation Method 1
The DC voltage provided by the power supply 11 is switched across the phase windings 16 of the machine 12 by a power converter 13 under the control of the electronic control unit 14
Implementation Method 2
The inductance of each phase winding varies as the rotor rotates because of the saliency of the magnetic structure
Data Source
AI summary
A switched reluctance machine has salient poles on the stator and rotor. The windings of the machine are supplied from a converter which provides energization at a chosen rate. The windings of the machine may be energized at the rate at which the rotor poles pass the stator poles, or it may be operated at a fraction of that rate by energizing the windings to cooperate with every second, third or fourth rotor pole. This can extend the output of the machine.