Inverter Controller Fault Reconfiguration for Electric Motor Noise Reduction
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Solution Overview
Problem
Electric motors experience torque ripple and generate noise when an inverter fault occurs, leading to suboptimal operation and potential damage.
Innovation Solution
A controller configuration that detects inverter faults and reconfigures the remaining switches to prevent torque ripple by placing coil windings in a short circuit configuration only when the rotor is above a certain velocity, thereby minimizing drag torque and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inverter switches are placed in an open circuit configuration to disable the motor following an inverter fault, then the motor is safely disabled, but the motor experiences torque ripple and generates acoustic noise
Solution Approach 1:
The patent changes the electrical configuration parameter of the coil windings from an open circuit state to a short circuit state. By shorting the coil windings through the low-side switches, the back electromotive force is redirected away from the power source, eliminating torque ripple and acoustic noise while maintaining safe motor disablement
Solution Approach 2:
The patent converts the harmful back electromotive force generated by the disabled motor into a beneficial effect by routing it through the low-side switches to ground. This transforms the potentially damaging voltage spike into a controlled current path that prevents torque ripple and noise while protecting the power source
2Object-generated harmful factors
If the coil windings are short circuited to prevent torque ripple, then torque ripple and noise are eliminated, but drag torque increases when the rotor is stationary or at low velocity
Solution Approach 1:
The patent implements a dynamic control strategy where the inverter switch configuration changes based on rotor velocity. At low or zero velocity, switches remain in the traditional open circuit state to minimize drag torque. Above a threshold velocity, the switches transition to the short circuit state to eliminate torque ripple and noise, optimizing performance across different operating conditions
3Duration of action of moving object
If the inverter switches are kept in a closed circuit configuration to maintain motor operation, then continuous operation is maintained, but the fault causes the motor to generate noise and torque ripple
Solution Approach 1:
The patent implements periodic monitoring of inverter switch status and dynamically adjusts the switch configuration based on operational conditions. The system periodically assesses whether to maintain closed circuit operation or transition to short circuit configuration, creating a rhythm of operation that balances continuous motor function with noise and torque ripple elimination
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
Enables the safe disablement of electric motors during inverter faults without torque ripple and noise, ensuring smooth operation and reducing wear and tear.
Implementation Method 1
back electromotive force generated by the disabled motor
Implementation Method 2
a current carrying wire will experience a force when in the presence of a magnetic field
Data Source
AI summary
A controller for an electric motor system including a three phase bridge inverter having a plurality of high side switches and a plurality of low side switches, the controller comprising means arranged upon detection of a fault in one of the high side switches to place the remaining high side switches in a closed circuit configuration and the plurality of low side switches in an open circuit configuration and upon detection of a fault in one of the low side switches to place the remaining low side switches in a closed circuit configuration and the plurality of high side switches in an open circuit configuration to allow coil windings of an electric motor to be placed in a short circuit configuration.