Four-Phase Switched Reluctance Motor Torque Ripple Suppression
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Solution Overview
Problem
Switched reluctance motors experience significant torque ripple due to their double salient structure and switch-type exciting mode, which limits their application and ability to control torque smoothly, especially at high rotational speeds and within limited DC supply voltage and current constraints.
Innovation Solution
A method for three-level suppression of torque ripple in four-phase switched reluctance motors is achieved by setting specific torque thresholds and controlling the excited states of adjacent phases A and B, dividing the commutation process into intervals to manage torque within defined ranges, ensuring smooth torque output across a broader range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional torque control methods are used, then torque ripple can be suppressed within certain speed range, but at high rotational speeds the system loses ability to control and track desired current, flux linkage and torque
Solution Approach 1:
The patent divides the commutation process from phase A to phase B into two distinct intervals based on rotor position, with different torque threshold settings for each interval. This segmentation allows the control system to adapt to different operating conditions at various speeds, maintaining control effectiveness across the full speed range by applying appropriate threshold values for each segment of the commutation cycle.
2Reliability
If maximum endurable current of winding and volt-ampere capacity of semiconductor devices are considered, then current is limited but this makes the motor only able to output smooth torque within a limited range
Solution Approach 1:
The patent employs two different sets of torque thresholds (first set and second set) that are selectively applied based on rotor position intervals. By changing the threshold parameters according to the commutation interval, the system maintains effective torque control within the limited current range, expanding the operable range without exceeding device capacity constraints.
3Ease of manufacture
If double salient structure and switch-type exciting mode are used, then simple and firm structure with low manufacturing cost is achieved, but electromagnetic torque has large ripple
Solution Approach 1:
The patent implements a feedback control mechanism where torque thresholds are continuously monitored and compared with actual torque output. Based on the rotor position and torque deviation, the control system adjusts the excitation states of phases A and B, applying corrective actions to suppress torque ripple while maintaining the simple double salient structure and switch-type exciting mode.
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 effectively suppresses torque ripple and enables smooth control of direct and transient torque, ensuring the motor outputs smooth torque over a maximum range, with high universality and broad application prospects for various four-phase switched reluctance motor drive systems.
Implementation Method 1
switched reluctance motor outputs smooth torque
Implementation Method 2
double salient structure and switch-type exciting mode make the electromagnetic torque it outputs
Data Source
AI summary
A four-phase switched reluctance motor torque ripple three-level suppression method. A first set of torque thresholds is set in rotor position interval [0°, θr/4]. A second set of torque thresholds is set in rotor position interval [θr/4, θr/2]. Power is supplied to adjacent phase A and phase B for excitation. The power supplied for excitation to phase A leads the power supplied for excitation to phase B by θr/4. An entire commutation process from phase A to phase B is divided into two intervals. In rotor position interval [0°, θ1], phase A uses the second set of torque thresholds while phase B uses the first set of torque thresholds. Critical position θ1 automatically appears in the commutation process, thus obviating the need for additional calculations. Total torque is controlled between [Te+th2low and Te+th2up]. In rotor position interval [θ1, θr/4], phase A continues to use the second set of torque thresholds, phase B continues to use the first set of torque thresholds, and the total torque is controlled between [Te+th1low and Te+th1up]. This suppresses torque ripples of a four-phase switched reluctance motor and provides great engineering application values.