Detecting Interrupted Motor Phases via Induced Voltage Comparison
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Solution Overview
Problem
Electric motors with three windings can experience excessively high phase currents due to interruptions in one of the phases, which can lead to overheating or overloading, and existing methods fail to effectively detect such faults without additional sensors or components.
Innovation Solution
A method using a control unit to measure induced voltages on outer conductors of an electric motor, comparing them to detect differences in voltage or frequency, allowing for the identification of an interrupted phase without additional sensors, and implementing self-protection measures like deactivating or reducing current to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional sensors or components are used to detect phase interruptions, then detection reliability is improved, but device complexity and cost increase
Solution Approach 1:
The existing outer conductors that carry power to the motor phases are made to serve a dual function: they continue to supply power while simultaneously acting as measurement conduits for detecting phase interruptions. By measuring induced voltages on these existing conductors during brief deenergization periods, the system achieves reliable fault detection without adding any sensors or measurement components.
Solution Approach 2:
The motor controller utilizes its own existing infrastructure (outer conductors and control timing) to perform self-diagnosis. The system monitors itself by measuring induced voltages on conductors it already controls, eliminating the need for external monitoring equipment and achieving cost-effective reliability.
2Loss of time
If induced voltage measurements are taken during motor operation, then detection speed is improved, but measurement accuracy may deteriorate due to voltage interference
Solution Approach 1:
The system performs measurements during periodic brief deenergization intervals that occur naturally in PWM-controlled motor operation. By synchronizing measurements with these predetermined time windows when switching elements are known to be in specific states, the system achieves both timely detection and accurate measurements free from active voltage interference.
Solution Approach 2:
The control system proactively creates measurement opportunities by timing the voltage measurements to coincide with predetermined periods when phases are deenergized. This preliminary planning of measurement windows ensures that measurements are taken under optimal conditions without delaying fault detection.
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
The method effectively prevents unnecessary high phase currents and potential damage by detecting interrupted phases within the existing motor controller, ensuring the electric motor operates safely without requiring additional components or sensors.
Implementation Method 1
voltages induced in the windings are determined on outer conductors of the electric motor by means of at least one measuring unit
Data Source
AI summary
A method for determining an interrupted motor phase of an electric motor having at least three windings by means of a control unit is disclosed, wherein voltages induced in the windings are determined on outer conductors of the electric motor by means of at least one measuring unit, wherein the measuring unit is connected to at least one outer conductor of the electric motor via at least one resistor, the induced voltages of the outer conductors of the electric motor are compared with one another, and an interrupted motor phase is registered if the induced voltage differs or if a frequency of the induced voltage differs. A control unit, a computer program and a machine-readable storage medium are also disclosed.