N-Phase Motor Switching Sequence to Limit Current Peaks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for switching on and off electrical machines in motor vehicles often result in unwanted current peaks and high electrical and mechanical loads, particularly at high speeds, due to interactions between phase voltage and flywheel voltage.
Innovation Solution
Determining an optimal switching time by evaluating parameters influencing the magnet wheel voltage, ensuring that phase voltage is applied or separated from the stator winding at a point where no undesired current peaks occur, thus avoiding high loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If phase voltage is switched on first, then switching sequence is simple, but phase current may overshoot causing high electrical and mechanical loads
Solution Approach 1:
The patent applies preliminary action by first switching on the excitation voltage to generate a flywheel voltage in the stator winding before switching on the phase voltage. This preliminary generation of flywheel voltage ensures that when phase voltage is applied, the current peak is limited and controlled, preventing harmful current overshoot and electrical loads on the electrical machine.
2Productivity
If electrical machine is switched on at high speeds, then productivity is improved, but unwanted current peaks and high loads occur
Solution Approach 1:
The patent applies preliminary action by first establishing the excitation voltage and generating the flywheel voltage in the stator winding before applying the phase voltage, regardless of the rotational speed of the electrical machine. This preliminary step ensures that at any speed including high speeds, the phase voltage is applied under controlled conditions with the flywheel voltage already present, preventing current peaks and harmful loads while enabling productivity improvement through speed-independent switching.
Solution Approach 2:
The patent employs feedback by continuously monitoring the flywheel voltage parameter and using this information to determine the optimal switching moment for phase voltage application at any rotational speed. The control unit adjusts the switching timing based on the evaluated flywheel voltage, ensuring that even at high speeds where productivity is improved, the phase voltage is switched on at the precise time when it does not cause current peaks or high electrical and mechanical loads.
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
Enables smooth and efficient switching of electrical machines independent of vehicle speed, reducing electrical and mechanical loads during operation, and allowing for easy startup even at high speeds without waiting for speed to fall below a certain limit.
Implementation Method 1
a parameter influencing a magnet wheel voltage is evaluated. The flywheel voltage is a fictitious auxiliary variable. When the machine is idling, it corresponds to the voltage that is induced in the stator winding by the current-carrying rotor winding or field winding (pole wheel)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a method for switching on or switching off an n-phase electric motor (110) in a motor vehicle, wherein the n-phase electric motor (110) has a rotor with a rotor winding (101) and a stator with an n-phase stator winding exhibits, wherein an exciter current can be applied to the rotor and an n-phase phase voltage can be applied to the stator, wherein the exciter current is switched on or off, a parameter which influences a magnet wheel voltage is determined and the phase voltage is switched on or off when the parameter which influences the magnet wheel voltage reaches a specific threshold value.