Motor Inverter Control for Consistent d-q Current Commands
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing motor control systems face challenges in achieving consistency between d-axis and q-axis current commands, particularly during weakening magnetic field control, leading to inconsistent motor behavior and prolonged control times.
Innovation Solution
A motor control device that generates a first d-axis current command based on an inter-line voltage command and a q-axis current command based on the d-axis current command, using an inverter and current command generation means to ensure consistency, with a selection mechanism for switching between different current commands based on the execution of weakening magnetic field control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If d-axis current command and q-axis current command are individually generated, then the operable range of the motor can be expanded, but the consistency between d-axis and q-axis current commands cannot be achieved
Solution Approach 1:
The patent implements feedback control by calculating the actual inter-line voltage from the generated current commands and comparing it with the target inter-line voltage. Based on this comparison, the d-axis current command is adjusted to ensure that the generated voltage does not exceed the inverter's output capability, thereby maintaining consistency between d-axis and q-axis current commands while expanding the operable range.
Solution Approach 2:
The patent dynamically adjusts the d-axis current command parameter based on the motor's operating state and the inverter's voltage output capability. By changing the d-axis current command according to the actual inter-line voltage conditions, the system maintains command consistency across different operating points while expanding the overall operable range.
2Adaptability or versatility
If d-axis current command and q-axis current command are individually generated, then flexibility in control is improved, but the control time increases and motor behavior cannot be controlled as target
Solution Approach 1:
The patent performs preliminary calculation of the target inter-line voltage based on the current commands before actual motor control execution. By pre-calculating and validating the voltage constraints, the system avoids iterative adjustments during real-time control, thereby reducing control time while maintaining the flexibility of individual d-axis and q-axis current command generation.
3Speed
If weakening magnetic field control is executed with individually generated current commands, then high speed operation is enabled, but command inconsistency occurs leading to oscillations
Solution Approach 1:
During weakening magnetic field control at high speeds, the patent continuously monitors the inter-line voltage and provides feedback to adjust the d-axis current command. This feedback mechanism ensures that the d-axis and q-axis current commands remain consistent even under high-speed operating conditions, preventing oscillations and maintaining motor behavior stability.
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 ensures rapid stabilization of motor behavior by achieving consistency between d-axis and q-axis current commands, reducing oscillations and stabilizing motor operation more quickly, while also allowing for reduced calculation processing when weakening magnetic field control is not executed.
Implementation Method 1
an inverter that converts a direct current voltage into a three-phase alternating voltage and outputs the three-phase alternating voltage to a motor
Data Source
Figure 1
Figure 2~3
Figure 4A~4D
AI summary
Provided are: a motor control device with which consistency between a d-axis current command and a q-axis current command can be achieved in response to target motor control; and a compressor comprising the motor control device. A motor control device 1 comprises: an inverter (3) that converts DC voltage into three-phase AC voltage and outputs the three-phase AC voltage to a motor; and an inverter control means (10) that controls the inverter. The motor control device performs weakening magnetic field control by flowing negative current to a d-axis current (id). The motor control device also comprises a current command generation means (24) that, when the weakening magnetic field control is being executed, generates a first d-axis current command (id1*) on the basis of an inter-line voltage command including a d-axis voltage command (vd*) and a q-axis voltage command (vq*) of the motor, and generates a first q-axis current command (iq1*) on the basis of the first d-axis current command.