Electric Motor Control via Linearized Current Profiles
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Solution Overview
Problem
The existing methods for controlling permanent-magnet synchronous machines require complex parameterization and current measurement to set precise current profiles, leading to unstable operating states and time-consuming adjustments due to aging effects.
Innovation Solution
A method that applies variable phase voltages based on a linearized current profile, estimating magnetic flux changes and using self- and coupling inductances to determine phase voltages without current measurement, allowing for open-loop operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If current measurement and complex current control are used to set precise current profiles, then manufacturing precision of current profile is improved, but device complexity increases and stability deteriorates
Solution Approach 1:
The patent extracts and removes the current measurement function and complex current control loop from the system. Instead of measuring actual phase currents and adjusting them through feedback control, the invention calculates required phase voltages directly from the desired current profile and machine parameters, eliminating the need for current sensors and complex control algorithms while maintaining current profile precision
Solution Approach 2:
The patent replaces the mechanical/electrical measurement and feedback control system with a computational approach. By using voltage calculations based on predefined machine parameters (inductances, resistances) and desired current profiles, the system substitutes physical current measurement and active control with mathematical computation and direct voltage application
2Manufacturing precision
If empirical parameterization of phase voltages is performed to achieve desired current profiles, then manufacturing precision is improved, but loss of time increases due to time-consuming parameterization and re-parameterization
Solution Approach 1:
The patent performs preliminary characterization of the machine's electrical parameters (inductances, resistances, back-EMF coefficients) during manufacturing or initial setup. These parameters are stored and reused for all subsequent operations, eliminating the need for repeated empirical parameterization. The system pre-calculates the relationship between voltages and currents based on these fixed parameters, allowing rapid generation of voltage profiles without time-consuming re-parameterization
Solution Approach 2:
The patent transforms the approach from empirical parameter adjustment to direct parameter utilization. Instead of iteratively adjusting voltage parameters to match desired current profiles, the system uses the machine's inherent electrical parameters (L, R, back-EMF coefficients) to directly compute the required voltages, converting a time-consuming empirical process into a rapid computational one
3Manufacturing precision
If phase currents are measured and adjusted through current control to minimize noise, then manufacturing precision is improved, but device complexity increases and reliability decreases due to unstable operating states
Solution Approach 1:
The patent removes the current measurement and feedback control mechanisms that cause instability. By calculating voltages directly from desired current profiles and machine parameters without measuring actual currents, the system eliminates the feedback loop that can create oscillations and unstable operating states, thereby improving reliability while maintaining noise control through precise voltage control
Solution Approach 2:
The patent implements an open-loop control approach where voltages are calculated based on desired outcomes without feedback from actual current measurements. This eliminates the feedback-induced instability while maintaining precision through accurate voltage calculation based on well-characterized machine parameters, improving operational 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 simplifies the parameterization process, reduces complexity, and stabilizes the operation of permanent-magnet synchronous machines by eliminating the need for current measurement, thereby minimizing noise and adapting to changes in electrical properties.
Implementation Method 1
the phase voltage to be applied for each phase is also determined as a function of an estimated change in a respective magnetic flux, the changes in the magnetic fluxes being determined using the phase currents specified by the phase current profile
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
The invention relates to a method and a device for operating a multi-phase electric machine (1) by applying variable phase voltages (Ux), comprising the following steps: - providing a phase current profile that indicates a rotor position-dependent curve of the respective phase current (Ix) for each phase of the electric machine (1); - determining the constant phase voltage (Ux) to be applied for each phase during a predefined time window depending on phase current information that indicates a linearized curve of the phase current (Ix) to be applied between the phase current (Ix) of the phase predefined by the phase current profile at the beginning of the predefined time window and the phase current (Ix) of the phase predefined by the phase current profile at the end of the predefined time window.