Synchronous Machine Control With DC Bus Voltage Feedback
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Solution Overview
Problem
Existing control methods for synchronous electrical machines, such as synchro-reluctant and permanent magnet machines, are not robust to DC bus voltage limits, leading to inefficiencies and inaccurate determination of voltage limits, which can result in overuse or underuse of inverter bus voltage.
Innovation Solution
A control method and system that utilize a feedback loop to determine a correction parameter based on torque and speed setpoints, incorporating a control model that links torque, corrected control variables, and current setpoints, ensuring optimal and robust use of DC bus voltage through a mapping like MTPA, and using proportional-integral regulators and estimators to adjust current setpoints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing control methods are used for synchronous electrical machines, then the control system is simpler, but the system is not robust to DC bus voltage limits and leads to inaccurate determination of voltage limits
Solution Approach 1:
The patent implements a feedback loop that continuously monitors the actual DC bus voltage and compares it with the voltage limit. Based on this comparison, the system adjusts the current setpoints to ensure the voltage limit is not exceeded. This feedback mechanism enhances the robustness of the control system to DC bus voltage limits while maintaining accurate voltage limit determination.
2Speed
If defluxing operation is implemented to increase rotational speed in voltage saturation regime, then the mechanical torque decrease is limited, but the control complexity increases
Solution Approach 1:
The patent implements defluxing operation by dynamically changing the current setpoints in the voltage saturation regime. When the DC bus voltage approaches the voltage limit, the system adjusts the direct and quadrature current components to reduce the magnetic flux, thereby enabling the rotational speed to increase while limiting the decrease in mechanical torque. This parameter change approach allows speed enhancement with manageable control complexity.
3Use of energy by moving object
If MTPA mapping is used to determine current setpoints, then the torque per ampere is maximized, but the voltage limit determination accuracy is compromised
Solution Approach 1:
The patent combines MTPA mapping with a feedback mechanism that monitors the actual DC bus voltage. The system uses MTPA mapping to determine initial current setpoints for maximum torque per ampere efficiency, then applies feedback adjustment based on the monitored voltage to ensure accurate voltage limit determination. This combination maintains energy efficiency while improving voltage limit accuracy.
4Productivity
If the DC bus voltage is overused or underused, then the inverter performance is suboptimal, but detecting and correcting this accurately is difficult
Solution Approach 1:
The patent implements a feedback loop that continuously monitors the actual DC bus voltage and compares it with the voltage limit to detect overuse or underuse conditions. Based on this detection, the system automatically adjusts the current setpoints to optimize inverter performance. This feedback mechanism makes voltage limit detection accurate and enables real-time optimization of inverter productivity.
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
Ensures efficient and robust use of DC bus voltage, improving the performance and efficiency of synchronous electrical machines by maintaining optimal voltage levels and enabling defluxing operations.
Implementation Method 1
Defluxing therefore consists of generating a magnetic field induced by the currents in the stator to compensate, at least in part, for the effect of the rotor's magnetic field
Implementation Method 2
The OND inverter is configured to route electrical energy between the DC source and each phase of the stator of the synchronous electrical machine MEL
Implementation Method 3
Such rotating electrical machines are advantageous in that, when a so-called 'voltage saturation' regime is reached, it is still possible to increase the rotational speed of the rotor of the machine while significantly limiting the decrease in the mechanical torque supplied by the rotating machine
Data Source
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AI summary
The present invention relates to a method and a system for controlling a synchronous electric machine (MEL) driven by an inverter (OND), in which the control of the inverter is determined. The method and system of control according to the invention use a control model according to the torque setpoint (TQsp) and a corrected control variable (VARcorr), the correction being implemented by means of a feedback loop.