Separately Excited Synchronous Machine Loss Optimization
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Solution Overview
Problem
Separately excited synchronous machines in motor vehicles face challenges in optimizing losses during operation, particularly in hybrid vehicles where safety and efficient energy use are critical, as existing control methods do not effectively manage losses to achieve high control dynamics.
Innovation Solution
A control method and device that provide reference and maximum values for stator and rotor currents, stored in lookup tables, to minimize losses by reducing the reference torque when maximum values are reached, using field-oriented control and current derating techniques to optimize torque and current control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If reference values for stator and rotor currents are provided based on predetermined reference torque to minimize losses, then energy efficiency is improved, but control dynamics may be limited due to lookup table constraints
Solution Approach 1:
The patent pre-calculates and stores current reference values in lookup tables that correspond to loss-minimal operating points for different reference torque values. This preliminary preparation enables the control system to quickly retrieve optimal current values without real-time complex calculations, thus maintaining high control dynamics while achieving loss optimization.
Solution Approach 2:
The control method continuously compares reference current values with maximum permissible current values and dynamically adjusts the reference torque when limits are reached. This feedback mechanism ensures the system operates within safe boundaries while maintaining optimal efficiency, resolving the contradiction between loss minimization and control responsiveness.
2Loss of energy
If maximum values for stator and rotor currents are enforced to limit permissible losses, then energy efficiency is improved, but the machine may experience reduced power output
Solution Approach 1:
The patent implements dynamic adjustment of the reference torque based on real-time comparison between reference current values and maximum permissible values. When maximum current values are reached, the reference torque is reduced by one torque value, allowing the system to adaptively balance loss limitations with power output requirements rather than applying fixed constraints.
Solution Approach 2:
The control method changes operating parameters (reference torque and reference currents) based on the comparison results between maximum and reference values. By dynamically adjusting these parameters, the system optimizes the balance between limiting losses and maintaining adequate power output across different operating conditions.
3Reliability
If separately excited synchronous machines are used instead of permanent magnet machines to enable switching off excitation current, then safety is improved, but additional losses occur due to excitation current requirements
Solution Approach 1:
The patent optimizes the excitation current parameters by providing reference values that correspond to loss-minimal operating points. By carefully controlling the magnitude and timing of the excitation current, the system achieves the safety advantage of switchable excitation while minimizing the associated energy losses through parameter optimization.
Solution Approach 2:
The patent converts the potentially harmful effect of excitation losses into a benefit by using the excitation current control as a means to achieve both safety (through switchable excitation) and efficiency (through loss-minimal operating points). The excitation current, which could be seen as a source of losses, is instead used as a controlled parameter to enable safe operation at optimized efficiency points.
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 enables loss-optimized operation with high control dynamics, reducing thermal overload and energy consumption in electrical machines, particularly in motor vehicles, by dynamically adjusting currents to limit maximum permissible losses.
Implementation Method 1
a rotor with a winding is used through which an excitation current flows via slip rings. This generates a magnetic excitation flux, or rotor flux, which interacts with a rotating field generated by the energized stator windings
Data Source
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AI summary
The invention relates to a regulating method and device for loss-optimized operation of a separately excited synchronous machine having a stator and a rotor, including the steps of: making reference values for stator and rotor currents available, wherein the reference value for the stator current and/or the reference value for the rotor current or an auxiliary parameter representing the reference value of the stator current and/or an auxiliary parameter representing the reference value of the rotor current is dependent on a predefined reference torque, making maximum values for stator and rotor currents available, comparing reference values for the stator and/or rotor currents or an auxiliary parameter representing the reference value of the stator current and/or an auxiliary parameter representing a reference value of the rotor current to the corresponding maximum values and reducing of the reference torque by a torque value if at least one of the reference values reaches or exceeds the corresponding maximum value.