Electronically Commutated Motor Switch Testing via Test Current Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Defective semiconductor switches in electronically commutated electric motors, particularly in power steering systems, can lead to impaired steering performance due to short-circuits, which existing technologies fail to effectively detect and address before motor operation.
Innovation Solution
The control unit of the electric motor is designed to test the function of semiconductor switches by feeding a test current into their outputs, detecting output voltage, and determining switch defects without moving the rotor, using voltage dividers and semiconductor switch pairs to identify defects in both semiconductor and isolating switches, allowing for pre-operation testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If semiconductor switches are tested by injecting current during motor operation, then defective switches can be detected, but the motor must be running which causes loss of time and prevents pre-operation testing
Solution Approach 1:
The patent implements preliminary testing of semiconductor switches by injecting test currents through the power output stage before the motor is operated. The control unit activates test current sources that flow through the semiconductor switches and disconnect switches, allowing defect detection to occur prior to motor startup, thereby eliminating the need to run the motor for testing purposes
2Measurement precision
If test current is injected into semiconductor switch outputs, then switch function can be detected, but additional testing components increase device complexity
Solution Approach 1:
The patent makes the power output stage multi-functional by enabling it to perform both its primary function of driving the motor and a secondary function of testing semiconductor switches. The existing power output stage components are utilized for testing by injecting test currents through the same output paths, allowing defect detection without adding separate dedicated testing hardware, thus maintaining system simplicity while achieving precise switch function measurement
Solution Approach 2:
The power output stage tests itself by using its own structure and components to detect defects in its semiconductor switches. The control unit activates test current sources that flow through the power output stage components, allowing the system to self-diagnose without requiring external testing equipment or additional complex testing infrastructure
3Reliability
If rotor is stationary during testing, then pre-operation testing is enabled, but torque generation cannot be tested
Solution Approach 1:
The patent segments the testing process into two distinct phases: a pre-operation phase where semiconductor switch defects are detected with the rotor stationary, and an operational phase where torque generation and motor performance are tested with the rotor rotating. This segmentation allows each type of testing to be performed under optimal conditions, with the stationary testing preventing defective switches from causing damage before operation
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 enables the detection of defective semiconductor switches before motor operation, preventing steering difficulties by ensuring the integrity of the power output stage, thereby enhancing the reliability of the electric motor in power steering systems.
Implementation Method 1
the control unit is configured to detect the output voltage generated at an output of the power output stage and to determine the function of at least one semiconductor switch as a function of the output voltage
Implementation Method 2
the control unit is connected to the outputs of the semiconductor switch pairs and is configured to control the semiconductor switches and the semiconductor disconnect switches to open
Implementation Method 3
The electric motor preferably has at least one voltage divider connected to the output of the power output stage. The voltage drop across the voltage divider at the output of the power output stage can be measured
Data Source
Figure 1
AI summary
The invention relates to an electronically commutated electrical motor. The electronically commutated electrical motor has at least two stator coils and an in particular permanent magnetic rotor. The electrical motor also has a power output stage having semiconductor switches, wherein the power output stage has a semiconductor switch pair for every stator coil. The electrical motor also has a control unit which is connected to the power output stage and designed to actuate the semiconductor switches to electrify the stator coils to generate a magnetic rotary field. The power output stage has at least one semiconductor isolating switch, in particular one for every stator coil, wherein the semiconductor isolating switch connects an output of a semiconductor switch pair to an output of the power output stage, wherein the output of the power output stage is connected to a stator coil. According to the invention, the control unit of the electrical motor is connected to the outputs of the semiconductor switch pairs and designed to supply a test current to at least one output of a semiconductor switch pair, preferably to every output of the semiconductor switch pairs. The control unit is preferably designed to detect output voltage generated at an output of the power output stage and to determine a function of at least one semiconductor switch of the semiconductor switches in dependence on the output voltage.