Rotary Machine Current Control Using a Shared Minimum DC Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In rotary machines with multiple systems controlled by different DC power supplies, mismatches occur due to differences in DC voltages, leading to inconsistent electric current flow.
Innovation Solution
A rotary machine control device with a first and second inverter, each controlled by a respective controller, generates command values based on the minimum DC voltage to synchronize electric current flow across systems, using a d-axis and q-axis electric current control system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If independent control systems with separate DC power supplies are used for each inverter, then system redundancy and independence are improved, but mismatch between systems occurs due to DC voltage differences
Solution Approach 1:
The patent changes the control parameter from using each system's own DC voltage to using the minimum DC voltage among all systems. This parameter change ensures that all inverters operate with a common reference voltage, eliminating mismatches caused by DC voltage differences while maintaining system independence and redundancy
Solution Approach 2:
The patent creates an equipotential reference by having all control systems use the same minimum DC voltage value. This establishes a common voltage baseline across independent systems, ensuring consistent electric current command values are generated despite differences in actual DC power supply voltages
2Stability of the object's composition
If DC voltage difference compensation is implemented, then system synchronization is improved, but control complexity increases
Solution Approach 1:
The patent merges the voltage reference generation function across all independent control systems by having them collectively determine and use the minimum DC voltage. This consolidation approach achieves synchronization without requiring complex communication protocols or centralized control, thereby limiting the increase in control complexity
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A rotary machine control device includes: a first inverter that applies an alternating-current voltage to three-phase windings of a first system included in a rotary machine, according to a first direct-current voltage; a second inverter that applies an alternating-current voltage to three-phase windings of a second system included in the rotary machine; a first controller that generates a command value of a d-axis electric current of the first system, according to a direct-current voltage minimum value and a command value of the rotary machine, the direct-current voltage minimum value being a lower one of the first direct-current voltage and the second direct-current voltage, that generates a command value of a q-axis electric current of the first system, according to the direct-current voltage minimum value and the command value of the d-axis electric current of the first system, and that controls the first inverter, according to the command value of the d-axis electric current of the first system and the command value of the q-axis electric current of the first system; and a second controller that generates a command value of a d-axis electric current of the second system, according to the direct-current voltage minimum value and the command value of the rotary machine, that generates a command value of a q-axis electric current of the second system, according to the direct-current voltage minimum value and the command value of the d-axis electric current of the second system, and that controls the second inverter, according to the command value of the d-axis electric current of the second system and the command value of the q-axis electric current of the second system.