Motor Control Device Field Weakening for High-Speed Torque
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Solution Overview
Problem
In motor control systems, particularly in image forming apparatuses, the rotor can stop rotating due to increased load torque exceeding the output-possible torque, leading to synchronization loss and inefficiencies in torque application, especially at higher rotational velocities where inductive voltages reduce the available voltage and torque.
Innovation Solution
A motor control device that includes a phase determiner, detector, and controller to perform field weakening by adjusting the excitation current component, reducing the magnetic flux intensity and controlling the torque current component to maintain rotor synchronization and prevent stoppage, by setting different degrees of field weakening based on rotational velocity and torque current values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotational velocity of the rotor is increased, then the productivity is improved, but the inductive voltage generated in the winding increases, causing the voltage that can be applied to the winding to decrease and the output-possible torque to become smaller
Solution Approach 1:
The patent applies parameter changes by adjusting the excitation current component (d-axis current) to control the intensity of magnetic flux through the winding. By changing the magnetic flux intensity parameter, the patent compensates for the torque reduction caused by high rotational velocity and inductive voltage, thereby maintaining adequate output-possible torque at high speeds
2Reliability
If the load torque applied to the rotor increases due to load degradation, then the reliability is worsened, but the output-possible torque becomes insufficient, causing the rotor to stop rotating
Solution Approach 1:
The patent applies dynamics by dynamically adjusting the excitation current component based on the rotational velocity and torque current component values. This dynamic adjustment allows the magnetic flux intensity to be optimized in real-time, ensuring that the output-possible torque remains sufficient even when load torque increases due to load degradation, thereby preventing rotor stoppage and maintaining continuous operation
Solution Approach 2:
The patent changes the magnetic flux intensity parameter through controlled adjustment of the excitation current component. This parameter change enables the motor to compensate for increased load torque and maintain adequate output torque, preventing rotor stoppage and ensuring reliable continuous operation
3Use of energy by moving object
If the excitation current component is controlled to be 0 to prevent power consumption increase, then the energy efficiency is improved, but the magnetic flux intensity is reduced, limiting the torque generation capability
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the excitation current component based on operational conditions (rotational velocity and torque current component values). Instead of maintaining excitation current at 0, the patent changes this parameter as needed to maintain adequate magnetic flux intensity and torque generation capability while minimizing power consumption through selective activation
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
Prevents rotor stoppage by maintaining adequate torque application and reducing power consumption, ensuring continuous operation even under increased load torque conditions and high rotational velocities.
Implementation Method 1
In a winding in each phase of a motor, an inductive voltage is generated by the rotation of a rotor
Implementation Method 2
a current component that is represented in a rotating coordinate system and influences the intensity of the magnetic flux through the winding
Data Source
AI summary
A motor control device includes a phase determiner, a detector, and a controller configured to control the driving current so that a deviation between a value of a torque current component of the driving current detected by the detector and a target value of the torque current component is reduced, and perform field weakening for weakening an intensity of magnetic flux through the winding. In a state where a value corresponding to a rotational velocity is greater than a first predetermined value, the controller sets a degree of the field weakening to a first degree in a case where the value of the torque current component is greater than a second predetermined value, and sets the degree of the field weakening to a second degree smaller than the first degree in a case where the value of the torque current component is smaller than the second predetermined value.