Rotary Electric Machine Field Excitation for Sudden Torque Response
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Solution Overview
Problem
Existing control devices for field winding type rotary electric machines experience a prolonged time lag in converging to a sudden increase in command torque due to the lower responsiveness of the field current compared to the stator current.
Innovation Solution
A control device that increases the degree of excitation of the field winding during a predetermined period following a sudden increase in command torque, accelerating the rise of the field current to enhance the torque convergence to the command torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of slots in the stator is increased to reduce torque ripple, then the manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent applies magnetic pole dynamic adjustment by changing the number of magnetic poles between forward and reverse rotation modes. This dynamic reconfiguration allows the motor to achieve different effective slot combinations without physically adding slots, thereby reducing torque ripple while avoiding the manufacturing complexity of increasing actual slot count
Solution Approach 2:
The patent changes the magnetic pole number parameter between forward and reverse rotation to achieve different torque characteristics. By adjusting this parameter, the system effectively creates different slot-pole combinations that reduce torque ripple without requiring additional physical slots in the stator
2Reliability
If the motor structure is designed for high precision and low torque ripple, then the control system complexity increases
Solution Approach 1:
The control system automatically determines whether to use forward or reverse rotation mode based on the desired rotation direction, and automatically adjusts the magnetic pole number accordingly. This self-service approach simplifies the control structure by eliminating the need for complex external coordination while maintaining low torque ripple performance
Solution Approach 2:
The patent uses reverse rotation mode with inverted magnetic pole arrangement to achieve the same rotational direction as forward rotation but with different torque characteristics. This inversion technique allows the control system to select the optimal rotation mode to minimize torque ripple without requiring additional control complexity
3Reliability
If the number of magnetic poles is increased to reduce torque ripple, then the motor speed range and response performance deteriorate
Solution Approach 1:
The patent dynamically adjusts the magnetic pole number based on the rotation mode (forward or reverse), allowing the motor to achieve high pole counts for torque ripple reduction only when needed, while maintaining low pole counts for high-speed operation. This dynamic adjustment preserves both torque quality and speed performance
Solution Approach 2:
The control system periodically switches between forward and reverse rotation modes with different magnetic pole configurations to achieve both low torque ripple and high speed performance at different time intervals, depending on the operational requirements
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
The solution shortens the time required for the rotary electric machine's torque to converge to the command torque by enhancing the responsiveness of the field winding excitation.
Implementation Method 1
an inverter 12 that controls the motor 11 by switching on and off at a high frequency
Implementation Method 2
a motor 11 including a stator 111 and a rotor 112
Data Source
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AI summary
A control device (30) is applied to a system including a rotary electric machine (40) having a stator (50) having a stator winding (52) and a rotor (60) having a field winding (70). The control device includes an operation unit that operates a current flowing through the stator winding and a field current flowing through the field winding in order to control a torque of the rotary electric machine to a command torque, and a determination unit that determines whether the command torque increases suddenly. The operation unit increases a degree of excitation of the field winding during a predetermined period from when it is determined that the command torque suddenly increase until the torque of the rotary electric machine converges to the command torque, compared to the degree of excitation of the field winding during a period after the predetermined period.