3-Phase Cable Error Detection Using Shunt Resistor Voltage Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing current sensing methods, such as hall-type and shunt resistor current sensing, face challenges in accurately determining errors due to external magnetic fields and overlapping error determinations with cable cutouts, leading to increased costs and reduced accuracy.
Innovation Solution
An error determining apparatus and method that includes a resistor in each phase of a 3-phase cable, a voltage sensing device, and a sensing controller to differentiate between faulty resistors and open cables by analyzing sensing voltage and 3-phase current sums, determining errors based on predetermined voltage ranges and current conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shunt resistor current sensing is used to reduce costs and respond to large current, then cost and responsiveness are improved, but error determination becomes difficult due to fixed output voltage at 0 A or minimum/maximum voltage repetition
Solution Approach 1:
The error determination method dynamically adapts to the operating conditions by switching between different determination schemes based on the operating mode (current control mode vs. voltage control mode). In current control mode, the system checks if sensing voltage equals 2.5V while current reference is non-zero. In voltage control mode, the system checks for minimum or maximum voltage repetition. This dynamic adaptation resolves the contradiction by providing accurate error determination across different operating conditions without requiring complex additional hardware.
Solution Approach 2:
The invention changes the determination parameters based on operating conditions. Instead of using a single fixed threshold, the system uses 2.5V threshold in current control mode and minimum/maximum voltage thresholds in voltage control mode. This parameter change allows the system to accurately determine errors in shunt resistors across different operating modes, resolving the contradiction between reliability and complexity.
2Measurement precision
If hall-type current sensing is used for accurate current detection, then measurement precision is improved, but responsiveness is reduced due to external magnetic field interference and cost increases
Solution Approach 1:
The invention replaces the hall-type current sensor (which uses magnetic field sensing) with a shunt resistor-based current sensor (which uses voltage measurement). This substitution eliminates the sensitivity to external magnetic fields and improves responsiveness, as voltage measurement is instantaneous and not affected by magnetic interference. The trade-off in measurement precision is resolved through the adaptive error determination method that accounts for shunt resistor characteristics.
3Reliability
If conventional error determination methods are used for hall sensors, then open/short errors are detected, but cable cutout errors cannot be distinguished from sensor errors
Solution Approach 1:
The invention segments the error determination process into distinct schemes based on operating modes. By dividing the determination logic into current control mode scheme and voltage control mode scheme, the system can identify whether an error is due to sensor failure or cable cutout. In current control mode, sensor errors show 2.5V with non-zero current reference, while cable cutouts show 0A actual current. This segmentation resolves the contradiction by preserving error type identification capability.
Solution Approach 2:
The system uses feedback from the operating mode detection to select the appropriate error determination scheme. The controller continuously monitors the operating mode (current control or voltage control) and feeds this information back to the error determination logic. This feedback mechanism enables the system to correctly interpret sensing voltage readings in the context of the current operating mode, resolving the contradiction between reliable error detection and accurate error type identification.
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 enhances error detection accuracy and reduces incorrect determinations by distinguishing between shunt resistor faults and cable open errors, improving responsiveness and reducing costs compared to conventional methods.
Implementation Method 1
a voltage sensing device sensing voltage of opposite ends of the resistor by a current flowing into the resistor
Data Source
AI summary
An error determining apparatus of a driving device including a motor and a 3-phase inverter supplying power to the motor through a 3-phase cable may include a resistor provided in each phase of the 3-phase cable, a voltage sensing device sensing voltage of opposite ends of the resistor by a current flowing into the resistor, and a sensing controller determining whether the resistor is faulty or whether the 3-phase cable is opened, based on the sensing voltage of the voltage sensing device and a 3-phase current sum of the 3-phase inverter.