Synchronous Machine Voltage Control via Pulsed Short Circuit
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Solution Overview
Problem
In electric motor vehicles with permanently-excited synchronous machines, external driving, such as towing, leads to unstable voltage supply due to periodic charging and discharging cycles, resulting in prolonged start-up times and increased costs and complexity in maintaining a stable voltage for control devices and circuit breakers.
Innovation Solution
Implementing a method that regulates the active short circuit in a pulsed manner using a two-point controller to maintain the intermediate circuit voltage within a constant range by setting specific threshold values, allowing the control device and switching arrangement to remain active, reducing start-up cycles and eliminating dead times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the switching arrangement is activated as soon as possible to bring about the short circuit when the synchronous machine feeds energy into the vehicle electrical system, then the intermediate circuit voltage can be reduced, but the voltage supply becomes unstable due to periodic charging and discharging cycles
Solution Approach 1:
The patent applies periodic action by implementing a two-point controller that activates the switching arrangement periodically based on voltage threshold values. Instead of continuous activation, the controller switches between active and inactive states when the intermediate circuit voltage exceeds an upper threshold or falls below a lower threshold, creating a controlled periodic action that maintains voltage stability while preventing harmful overvoltage conditions.
2Object-affected harmful factors
If the active short circuit is maintained continuously, then the intermediate circuit voltage remains low, but the control device and switching arrangement require continuous energy supply which becomes unavailable during voltage drops
Solution Approach 1:
The patent implements self-service by designing a system where the two-point controller automatically manages the switching arrangement activation based on voltage threshold detection. The controller activates the switching arrangement only when the intermediate circuit voltage exceeds the upper threshold, and deactivates it when voltage falls below the lower threshold, eliminating the need for continuous external energy supply to the control device while maintaining voltage control.
3Stability of the object's composition
If the switching arrangement is activated frequently to maintain voltage control, then the intermediate circuit voltage remains stable, but the start-up time of the control device increases due to repeated voltage drops
Solution Approach 1:
The patent applies feedback by implementing a two-point controller that continuously monitors the intermediate circuit voltage and provides feedback signals to activate or deactivate the switching arrangement based on predefined threshold values. This feedback mechanism ensures voltage stability is maintained while minimizing the frequency of switching operations, thereby reducing the start-up time losses associated with repeated control device activation.
4Speed
If the switching arrangement is designed for rapid starting with extremely low voltages, then the start-up time is reduced, but the design becomes more difficult and costs increase
Solution Approach 1:
The patent implements parameter changes by introducing two distinct voltage threshold values (upper and lower thresholds) that define the activation and deactivation conditions for the switching arrangement. This parameter-based control approach allows the system to operate efficiently without requiring complex rapid-start designs, as the switching arrangement only needs to activate when voltage exceeds the upper threshold, simplifying the overall design while maintaining acceptable start-up performance.
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 ensures a stable and continuous voltage supply, reducing start-up times and maintaining safety during external driving by keeping the intermediate circuit voltage within a harmless range, thereby enhancing safety and reducing operational complexity and costs.
Implementation Method 1
the synchronous machine is operated in a generator mode, i.e., as a generator, so that a current is fed via the windings into the high-voltage intermediate circuit of the converter
Implementation Method 2
Energy generated by the synchronous machine and stored in the capacitor for operating the control device and the switching arrangement
Implementation Method 3
the switching arrangement is activated for short-circuiting the windings of the synchronous machine
Data Source
AI summary
A method for operating a motor vehicle is provided, having, as a prime mover, a permanently-excited synchronous machine with windings. The synchronous machine is connected to a vehicle electrical system of the motor vehicle via a converter having a switching arrangement and a capacitor in an intermediate circuit. The switching arrangement can be controlled via a control device connected to the vehicle electrical system. The permanently-excited synchronous machine is operated as a generator while being driven by external means. Energy generated by the synchronous machine and stored in the capacitor for operating the control device and the switching arrangement is provided when a first threshold value for the voltage in the intermediate circuit is exceeded. When a second threshold value for the voltage in the intermediate circuit is exceeded, the switching arrangement is activated for short-circuiting the windings of the synchronous machine.