Sensorless Rotor Position Control in Switched Reluctance Machines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sensorless rotor position monitoring methods for switched reluctance machines, such as signal injection and direct phase measurement, face inefficiencies at high operating speeds, particularly in ultra-high speed applications above 100,000 rpm, where they can adversely impact motor performance and increase losses.
Innovation Solution
A method involving energizing, freewheeling, and de-energizing phase windings in a reluctance machine, with sampling of phase current rate and amplitude changes to compute the angular position of the rotor, allowing for sensorless control without mechanical sensors, and optimizing the freewheeling period for reduced losses and improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signal injection methods are used for sensorless rotor position monitoring, then rotor position can be determined without mechanical sensors, but motor performance deteriorates and losses increase at high operating speeds
Solution Approach 1:
The patent changes the operating parameters by utilizing the natural freewheeling current characteristics during normal operation instead of injecting diagnostic pulses. By monitoring the rate of change of current during the freewheeling period when voltage across the phase winding is zero, the system achieves sensorless position monitoring without the performance degradation associated with signal injection methods at high speeds
2Measurement precision
If mechanical sensors are used for rotor position monitoring, then accurate rotor position data can be obtained, but the system complexity and mechanical dependency increase
Solution Approach 1:
The patent replaces mechanical sensors with an electronic-based sensorless monitoring method. By using the existing phase current and voltage signals along with the freewheeling period characteristics, the system eliminates mechanical sensors and their associated mounting complexity, while still achieving accurate rotor position determination through computational analysis of electrical parameters
3Loss of information
If diagnostic energization pulses are used for rotor position monitoring, then rotor position can be computed from inductance variation, but torque production is reduced and performance deteriorates at higher speeds
Solution Approach 1:
The patent enables the system to monitor rotor position using the existing operational currents and voltages during normal motor operation, particularly during the freewheeling period. Instead of requiring separate diagnostic pulses that interrupt torque production, the system extracts position information from the natural electromagnetic behavior during regular operation, thus maintaining full productivity while achieving position monitoring
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 enables accurate and efficient sensorless rotor position control in high-speed switched reluctance machines by minimizing machine inefficiencies and iron losses, eliminating the need for mechanical sensors, and enhancing power output.
Implementation Method 1
energising the phase winding to move the rotor relative to the stator
Implementation Method 2
During the freewheeling period current may circulate around the winding and the flux may be constant
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A method to control the rotor position in a reluctance machine is disclosed. The method involves energising the phase winding so to move the rotor relative to the stator, freewheeling current through the phase winding over a freewheeling period, sampling rate of change of phase current and amplitude of phase current, de-energising the phase winding and computing the angular position of the rotor.