Adjustable Pulse Injection for SR Machine Rotor Position
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Solution Overview
Problem
Conventional control schemes for switched reluctance (SR) machines face challenges in accurately determining rotor position and speed, especially at low speeds, due to errors from sensor misalignment and noise from pulsating torque, leading to inefficiencies and incorrect operation.
Innovation Solution
A control system that injects adjustable pulse signals into the stator phases based on torque and rotational speed signals to determine the rotor position, using a converter circuit and controller to modulate current peaks and injection timing, thereby reducing position and speed estimation errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor-based control schemes are used to detect rotor position, then position detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical sensor-based position detection with an electrical field-based method. Pulse signals are injected into stator phases and the resulting current responses are analyzed to determine rotor position, eliminating the need for mechanical speed wheels and position sensors. This substitution reduces device complexity while maintaining position detection capability.
Solution Approach 2:
The system uses the electric machine's own electrical characteristics and responses to determine rotor position. By injecting pulse signals and analyzing the machine's inherent current responses, the control system derives position information from the machine itself without requiring external sensors, making the system self-sufficient.
2Device complexity
If pulse signals are injected to determine rotor position sensorlessly, then device complexity is reduced, but measurement precision deteriorates due to pulsating torque noise
Solution Approach 1:
The patent dynamically adjusts pulse signal characteristics (amplitude, duration, frequency) based on operating conditions such as rotor speed and load. This dynamic adaptation allows the system to optimize signal injection parameters to minimize pulsating torque effects while maintaining accurate position detection, especially during light-load conditions where noise impact is most severe.
Solution Approach 2:
The system employs feedback mechanisms where the injected pulse signals and resulting current responses are continuously monitored and analyzed. The control system uses this feedback information to refine position estimates and compensate for noise effects, improving measurement precision despite the absence of physical sensors.
3Ease of operation
If fixed pulse injection parameters are used, then ease of operation is improved, but adaptability deteriorates under varying load conditions
Solution Approach 1:
The control system transitions from fixed to dynamic pulse injection parameters. The amplitude, duration, and timing of injected pulses are continuously adjusted based on real-time operating conditions including rotor speed, load torque, and phase current measurements, enabling the system to adapt to varying load conditions while maintaining accurate position determination.
Solution Approach 2:
The patent implements parameter changes in the pulse injection signals based on operating conditions. By modifying signal characteristics such as amplitude, pulse width, and injection timing according to load variations, the system maintains optimal performance across different operating points while preserving the simplicity of the sensorless 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 provides accurate and efficient rotor position determination without the need for costly sensors, enhancing the operational reliability and efficiency of SR machines, especially at standstill and low-speed operations.
Implementation Method 1
switched reluctance (SR) machines have received great interest for being robust and cost-effective. A typical SR machine includes a rotor and a stator, each of which may include a plurality of poles. During operation such as in the motoring mode, a rotational field is applied to the stator, which, through the magnetic reluctance effect, 'pulls' the rotor along
Data Source
AI summary
A control system is provided for an electric machine having a rotor and a stator. The control system has a converter circuit in electrical communication with the stator and a controller in electrical communication with the converter circuit. The controller is configured to receive a first signal indicating a torque applied to or output by the rotor and receive a second signal indicating a rotational speed of the rotor. The controller is also configured to determine at least one characteristic of a pulse signal based on at least one of the first or second signal. The controller is also configured to inject the pulse signal into one or more phases of the stator via the converter circuit according to the determined at least one characteristic. The controller is also configured to determine a position of the rotor based on the injected pulse signal.