Switched Reluctance Motor Voltage Compensation
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Solution Overview
Problem
Switched reluctance motors face challenges in controlling rotor position at high speeds due to variations in DC link voltage, which existing control law tables fail to account for effectively, leading to inefficient operation and increased memory usage.
Innovation Solution
A method that measures the applied DC link voltage and applies a correction to the angular position of phase winding energization, using a predetermined relationship stored in memory to ensure accurate control, reducing memory requirements and improving operational efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If control law tables are used to control rotor position at high speeds, then control precision is improved, but memory usage increases and the system becomes more complex
Solution Approach 1:
The patent extracts only the essential voltage compensation information from complex control law tables. Instead of storing complete multi-dimensional lookup tables, the invention stores a simplified voltage correction value or correction curve that can be applied to adjust the fundamental frequency, thereby reducing memory requirements while maintaining control precision.
Solution Approach 2:
The control approach is segmented into two parts: a base control frequency stored in memory and a voltage-dependent correction value also stored in memory. These segments are combined during operation to achieve precise control without requiring the entire control law table to be stored, thus reducing memory usage while maintaining precision.
2Device complexity
If DC link voltage variations are not compensated, then device complexity is reduced, but control reliability deteriorates at high speeds
Solution Approach 1:
The system performs preliminary measurement of the DC link voltage and applies a predetermined correction value before executing the main control operation. This advance compensation ensures that the fundamental frequency is adjusted according to actual voltage conditions, maintaining control reliability without adding complex real-time adjustment mechanisms.
Solution Approach 2:
The patent implements a feedback mechanism where the DC link voltage is measured and used to determine a correction value that adjusts the fundamental frequency. This closed-loop approach ensures that voltage variations are compensated, maintaining reliable control at high speeds while keeping the overall system relatively simple.
3Reliability
If complex voltage compensation methods are implemented, then control reliability is improved, but ease of operation deteriorates
Solution Approach 1:
The control system automatically measures the DC link voltage and applies the appropriate correction value without requiring manual intervention or complex operator decisions. The system self-adjusts the fundamental frequency based on voltage conditions, maintaining reliability while keeping operation simple and automatic.
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 allows for more straightforward control of electrical machines, reduces memory usage, and compensates for voltage variations, enhancing performance and cost-effectiveness in high-speed applications.
Implementation Method 1
measuring the applied DC link voltage
Data Source
AI summary
An electrical machine, such as a switched reluctance motor, has a rotor and a controller arranged to energize at least one electrically energizable phase winding in dependence on the angular position of the rotor. The controller may employ a control law table derived by applying a predetermined DC link voltage to the windings. Differences between an applied DC link voltage and the predetermined DC link voltage may be compensated by applying a predetermined correction to the angular position of energization of the phase winding in dependence on the value applied DC link voltage. Such a compensation factor may be derived from a relationship held in memory.