Triple-Phase Motor Control Attenuating Current Oscillations
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current systems for controlling synchronous electric motors face challenges in reducing current oscillations, which lead to torque oscillations and divergence in current regulators, especially when increasing power to 70kW, due to imprecise current measurements and harmonic contributions.
Innovation Solution
A control system that decouples phases to selectively attenuate current oscillations by determining reference currents and mitigation tensions, using a PID regulator and summators to adjust supply voltages, and applying attenuation equations to reduce current oscillations and torque fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power of the three-phase machine is increased to 70kW, then the power output is improved, but the current measurement precision deteriorates causing current oscillations and torque oscillations
Solution Approach 1:
A mitigation voltage is introduced as an intermediary signal to compensate for measurement inaccuracies. This mitigation voltage is calculated based on reference currents and added to the supply voltage to counteract the effects of imprecise current measurements, thereby reducing current oscillations and torque oscillations while maintaining high power output
Solution Approach 2:
The system implements feedback by continuously monitoring actual currents, comparing them with reference currents, and adjusting the mitigation voltage accordingly. This closed-loop control ensures that current oscillations are actively compensated for, maintaining measurement effectiveness even at high power levels where sensor precision deteriorates
2Device complexity
If standard current control is used without phase decoupling, then the control system is simpler, but current oscillations and torque oscillations increase
Solution Approach 1:
The control system is segmented into distinct functional blocks: a first PID regulator for supply voltage control, a second regulator for mitigation voltage control, and summators for combining voltages. This modular segmentation allows each block to handle specific tasks, improving current stability while keeping the overall system manageable through functional decomposition
3Stability of the object's composition
If mitigation voltage is added to reduce current oscillations, then current stability is improved, but the control system complexity increases
Solution Approach 1:
The mitigation voltage generation is merged with the existing supply voltage control system. The second regulator and summators are integrated into the control architecture, allowing current stability improvement through a unified control approach rather than adding completely separate systems, thereby limiting the increase in overall complexity
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
The system dynamically corrects supply voltages to reduce current oscillations and torque oscillations, enhancing the effectiveness of the current regulator and improving power delivery stability.
Implementation Method 1
VD and VQ voltages are created with an inverter, VF voltage is created with a chopper, these two systems being powered by a battery
Implementation Method 2
VD and VQ voltages are created with an inverter, VF voltage is created with a chopper, these two systems being powered by a battery
Implementation Method 3
A control system that decouples phases to selectively attenuate current oscillations by determining reference currents and mitigation tensions, using a PID regulator and summators to adjust supply voltages
Implementation Method 4
These currents create a magnetic field rotating in the machine. The rotor is traveled by a direct current which creates a magnetic field and makes it equivalent to a magnet. To carry out the mechanical torque, the stator magnetic field is piloted in quadrature
Data Source
Figure 1~2
AI summary
The invention relates to a method for controlling a triple-phase electrical machine (2) of a motor vehicle, said machine being supplied with chopped voltages. Said method includes a step of determining current set points for each phase of the electrical machine (2) on the basis of a torque request from the driver. The method includes the following steps, during which: the voltages of each phase of the electrical machine (2) are determined on the basis of the reference currents for each phase, of the measurements of the currents of each phase, and of the measurement of the magnetic rotation speed of the electrical machine (2); the attenuation voltages of current oscillations from each phase of the electrical machine are determined on the basis of the reference currents, measurements of the currents of each phase, as well as the measurement of the rotation speed of the magnetic field of the electrical machine (2); and set points for final voltages for supplying power to the electrical machine are determined by adding the power supply voltages, related to each phase, with the attenuation voltages related to the corresponding phases.