Field Coil Control for Rotational Electric Machine Torque Speed Trade-off
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Solution Overview
Problem
Permanent-magnet synchronous machines used in vehicle drive motors face limitations in simultaneously maximizing both rotational speed and output torque, requiring additional gear pairs or mechanical transmissions to adjust motor characteristics.
Innovation Solution
A rotational electric machine with a stator, rotor, field coil, acquisition unit, and motor characteristic control unit that adjusts direct current based on torque and rotational state information to dynamically control motor characteristics without the need for multiple gear pairs or mechanical transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the amount of magnetic flux by the permanent magnet is increased, then the maximum value of the output torque is increased, but the maximum value of the rotational speed is limited
Solution Approach 1:
The patent applies dynamics by making the motor characteristic changeable through a control unit that adjusts the field coil current. This allows the motor to dynamically switch between different magnetic flux levels, enabling high torque at low speeds and high speed at low torque, thus resolving the contradiction between maximum output torque and maximum rotational speed without mechanical gear pairs.
Solution Approach 2:
The patent changes the magnetic flux parameter by controlling the field coil current. By adjusting this parameter, the motor can operate in different modes: high magnetic flux for high torque and low magnetic flux for high speed. This parameter change approach allows the motor to overcome the fixed characteristic limitation and achieve both high torque and high speed requirements.
2Speed
If the amount of magnetic flux by the permanent magnet is decreased, then the maximum value of the rotational speed can be increased, but the maximum value of the output torque decreases
Solution Approach 1:
The control unit dynamically adjusts the field coil current based on the required operating conditions. When high rotational speed is needed, the control unit decreases the field coil current to reduce magnetic flux, enabling high-speed operation. When high torque is needed, the control unit increases the field coil current to enhance magnetic flux, thus resolving the contradiction between speed and torque through dynamic control.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the field coil current to control the magnetic flux level. This allows the motor to adapt its characteristics: reducing magnetic flux for high-speed operation and increasing magnetic flux for high-torque operation, thereby eliminating the need for mechanical transmission systems.
3Force
If a plurality of gear pairs or mechanical transmission is used to change motor characteristic, then both maximum rotational speed and maximum output torque can be increased, but the device complexity increases
Solution Approach 1:
The patent replaces the mechanical transmission system (gear pairs) with an electromagnetic control system. The control unit adjusts the field coil current to change the motor's magnetic flux and characteristic, achieving the same effect as mechanical gear changes but without the complexity of mechanical components. This substitution eliminates the need for multiple gear pairs while maintaining the ability to provide both high torque and high speed.
4Adaptability or versatility
If mechanical transmission components are added to adjust motor characteristics, then the adaptability of the drive system is improved, but the device complexity and number of parts increase
Solution Approach 1:
The control unit serves multiple functions: it controls the armature current, adjusts the field coil current to change magnetic flux, and adapts the motor characteristic to different operating conditions. This multi-functional control approach provides the adaptability previously achieved through multiple mechanical components, but with a single electronic control system, reducing overall device complexity.
Solution Approach 2:
The patent substitutes mechanical adjustment mechanisms with electronic control. The field coil current control provides adaptability for different motor characteristics without requiring physical gear pairs or transmission components, thereby improving versatility while minimizing the number of parts.
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 flexible adjustment of motor characteristics to achieve desired output characteristics for vehicles, allowing for increased rotational speed and torque without additional mechanical components.
Implementation Method 1
a stator configured to generate a rotation magnetic field in response to alternating current
Implementation Method 2
a rotor configured to rotate in response to the rotation magnetic field
Implementation Method 3
a field coil configured to excite the rotor in response to direct current
Data Source
AI summary
A rotational electric machine includes a stator configured to generate a rotation magnetic field in response to alternating current; a rotor configured to rotate in response to the rotation magnetic field; a field coil configured to excite the rotor in response to direct current; an acquisition unit configured to acquire manipulation information related to a torque generated by or caused to be generated by the rotor and a rotational state of the rotor; and a motor characteristic control unit configured to control the direct current based on the manipulation information and the rotational state acquired by the acquisition unit to control a motor characteristic.