Electromechanical Steering DC Bus Overvoltage Control
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Solution Overview
Problem
Existing electromechanical steering systems in vehicles face issues with generated electric currents causing overvoltages in the DC bus, leading to potential damage to electronics components, particularly in hybrid or electric vehicles with advanced on-board power supply systems.
Innovation Solution
A method and system that monitors the DC bus voltage level and uses the electric motors of the steering actuators to convert excess generated currents back into energy, preventing overvoltages by adapting the d-vector of the motor's rotor-referred d/q system through vector control, ensuring the DC bus voltage remains stable without affecting steering behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the electric motor of the feedback actuator is operated in generator mode to provide energy feedback, then energy efficiency is improved, but overvoltage damage to electronics components occurs
Solution Approach 1:
The patent converts the harmful effect of generated currents causing overvoltage into a beneficial effect by operating the electric motor in generator mode to provide energy feedback. The control system monitors DC bus voltage and actively manages the energy feedback process to prevent overvoltage conditions while maximizing energy recovery, thus transforming a potentially damaging situation into an energy-efficient solution.
Solution Approach 2:
The patent implements a feedback control mechanism where the control unit continuously monitors the actual voltage level of the DC bus and adjusts the operation of the electric motor accordingly. When the voltage exceeds the target level by a predetermined value, the control system modifies the generator mode operation to reduce current generation, thereby preventing overvoltage damage while maintaining energy efficiency as much as possible.
2Reliability
If the DC bus voltage is monitored and energy conversion is activated to prevent overvoltage, then electronics protection is improved, but system complexity increases
Solution Approach 1:
The patent makes the electric motor serve multiple functions: it can operate in motor mode to provide steering assistance and in generator mode to provide energy feedback. The same actuator and control system handle both propulsion and energy recovery functions, eliminating the need for separate systems and reducing overall system complexity despite the added voltage monitoring and control logic.
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
Effectively prevents overvoltages on the DC bus, protecting electronics and maintaining normal steering functionality by converting excess currents within the electric motors, thus avoiding damage and maintaining steering feel and performance.
Implementation Method 1
at least one electric motor which, depending on the driving situation, can be operated in a motor mode or in a generator mode
Data Source
AI summary
A method for operating an electromechanical steering system in a motor vehicle, wherein the steering system comprises at least one actuator having at least one electric motor, wherein the at least one electric motor is connected via a DC bus to an electrical on-board power supply system of the motor vehicle, comprises operating the at least one electric motor in a motor mode or a generator mode depending on the driving situation. At least one control unit of the steering system monitors an actual voltage level of the DC bus with respect to an exceedance of a target voltage level of the DC bus by a predetermined value, wherein, in the case of a detected exceedance by a first predetermined value, the actual voltage level is reduced by converting electrical energy in at least one of the electric motors. An electromechanical steering system is designed to be operated according to such a method.