Steering Control Short-Circuit Protection via Capacitor Current Extraction
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Solution Overview
Problem
Existing electronic control devices for electric motor vehicle steering systems lack reliable short-circuit protection and fault diagnosis, particularly due to inaccuracies in monitoring voltage drops across MOSFETs and inability to detect short circuits in charging capacitors, leading to potential battery discharge and operational failures.
Innovation Solution
An electronic control device with a current measuring device arranged in series with the capacitor and parallel to the inverter, which evaluates the current flow to detect direct current components indicative of short circuits, reducing ohmic losses and enabling differentiated error diagnosis through current direction analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage drop monitoring across MOSFETs is used for short-circuit detection, then some protection is provided, but measurement accuracy is insufficient due to parasitic line resistances and differences between phases
Solution Approach 1:
The patent extracts the current measurement function from the power supply path and places it specifically in the capacitor circuit. The current measuring device is connected in series with the capacitor to ground, separating the measurement function from the main power path. This allows accurate detection of capacitor current without being affected by parasitic resistances in the power supply lines, directly resolving the measurement accuracy issue while maintaining protection reliability.
2Reliability
If conventional monitoring methods are used, then some protection is provided, but short circuits in charging capacitors cannot be detected
Solution Approach 1:
The patent makes the monitoring system universal by designing it to detect all types of short circuits through a single measurement point. The current measuring device monitors capacitor current, which reflects the state of both the capacitor and the entire inverter system. This single measurement approach provides multi-functional detection capability for different fault types, achieving both improved protection coverage and detection versatility.
3Reliability
If current measurement is performed in the power supply path, then short-circuit detection is possible, but ohmic losses increase
Solution Approach 1:
The patent extracts the measurement function from the high-current power supply path and relocates it to the capacitor circuit. The current measuring device is connected in series with the capacitor to ground, which carries only the ripple current necessary for capacitor charging/discharging. This extraction eliminates the ohmic losses that would occur if measurement equipment were placed in the main power supply path, while still providing effective short-circuit detection capability.
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 solution provides reliable short-circuit protection by isolating faulty components from the power source, preventing battery discharge and allowing for accurate fault diagnosis, thus ensuring continuous operation of vehicle electrical systems.
Implementation Method 1
The current measuring device 4 is designed to output a short-circuit error signal as a function of the current intensity of an electrical current occurring in the power module 3
Data Source
Figure 1~2
AI summary
The invention relates to an electronic control device with short-circuit protection for actuating an electric motor (33) of an electromechanical motor vehicle steering system comprising a switching device (2) via which the electronic control device (10) can be connected to a power source (1), a power module (3) which is connected to the switching device (2) and to which the electric motor (33) can be connected in order to be supplied with electrical power, wherein the power module (3) contains an inverter (31) and at least one capacitor which is connected in parallel with the inverter (31), a current-measuring device (4) which is connected to the power module (3) and is designed to output a short-circuit fault signal in accordance with the strength of an electric current which occurs in the power module (3), and a control unit (5) which is connected to the current-measuring device (4) and has the purpose of controlling the switching device (2), wherein the control unit (5) is designed to trigger disconnection of the power module (3) from the power source (1) by means of the switching device (2) when the short-circuit fault signal is received, and wherein the current-measuring device (4) is designed to measure an electric current flowing through the capacitor (30) and to output the short-circuit fault signal on the basis of a direct-current component of the measured current.