Synchronous Reluctance Motor Current Vector Control Across Speed Ranges
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Solution Overview
Problem
Existing motor control devices for synchronous reluctance motors fail to output maximum torque and torque corresponding to a command value across all rotation speed areas, particularly in high rotation speed areas.
Innovation Solution
A motor control device that includes a first setting unit for setting a motor torque command value, a rotation speed detecting unit, a second setting unit for calculating armature current and phase angle command values based on rotation speed and torque command value, and a drive unit to control the motor using d-axis and q-axis current command values, with tables storing optimal command values for different operating points and rotation speeds to ensure maximum torque output across all speed ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If maximum output/speed control is performed in high rotation speed area, then rotation speed is improved, but motor torque output capability deteriorates
Solution Approach 1:
The control device dynamically switches between maximum torque/current control and maximum output/speed control based on the rotation speed. At low rotation speeds, maximum torque/current control is applied to optimize torque output. At high rotation speeds, maximum output/speed control is applied to optimize speed performance. This dynamic adaptation resolves the contradiction by allowing the system to achieve both high speed capability and adequate torque output in different operating conditions.
Solution Approach 2:
The control device changes control parameters (armature current command value and current phase angle command value) based on rotation speed. By storing pre-calculated optimal parameter combinations in tables for different speed ranges and selecting appropriate parameters dynamically, the system maintains optimal performance across the entire speed range, resolving the torque-speed trade-off.
2Force
If maximum torque/current control is performed in low rotation speed area, then motor torque is improved, but rotation speed capability deteriorates
Solution Approach 1:
The control device dynamically switches between maximum torque/current control and maximum output/speed control based on the rotation speed. At low rotation speeds, maximum torque/current control is applied to optimize torque output. At high rotation speeds, maximum output/speed control is applied to optimize speed performance. This dynamic adaptation resolves the contradiction by allowing the system to achieve both high speed capability and adequate torque output in different operating conditions.
Solution Approach 2:
The control device changes control parameters (armature current command value and current phase angle command value) based on rotation speed. By storing pre-calculated optimal parameter combinations in tables for different speed ranges and selecting appropriate parameters dynamically, the system maintains optimal performance across the entire speed range, resolving the torque-speed trade-off.
3Measurement precision
If separate control tables are used for maximum torque and maximum output, then control precision is improved, but device complexity increases
Solution Approach 1:
The control device divides the operating range into different segments (low speed and high speed areas) and uses separate control tables for each segment. The maximum torque table stores optimal parameters for low speed operation, while the maximum output table stores optimal parameters for high speed operation. This segmentation allows precise control for each operating condition without requiring a single complex control algorithm that would need to handle all conditions optimally.
Solution Approach 2:
The control device pre-calculates and stores optimal armature current command values and current phase angle command values in tables before operation. This preliminary action eliminates the need for complex real-time calculations during motor operation, reducing computational complexity while maintaining high control precision. The pre-stored tables contain all necessary control parameters for different operating conditions.
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
Enables the output of maximum torque and torque corresponding to a motor torque command value in all rotation speed areas, improving motor control efficiency and reliability.
Implementation Method 1
a rotor is rotated using a reluctance torque... a reluctance torque is generated due to a difference (Ld - Lq) between an inductance in the d-axis direction and an inductance in the q-axis direction
Data Source
Figure 1
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AI summary
A motor control device (12) includes: a second setting unit configured to set an armature current command value and a current phase angle command value based on a rotation speed and a motor torque command value; and a current vector setting unit configured to set a d-axis current command value and a q-axis current command value based on the armature current command value and the current phase angle command value. The second setting unit is configured to set the armature current command value and the current phase angle command value such that an armature current vector which is set based on the d-axis current command value and the q-axis current command value is included in an area surrounded by an armature current vector locus in maximum torque/current control and a vertical axis in a d-q coordinate system.