Electric Motor EMI Reduction via Isolation Relay
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric motors used in windshield wipers generate electromagnetic interference (EMI) due to pulses in the park disk's rotation, which can pose security risks and violate EMI control regulations, especially in military vehicles.
Innovation Solution
The motor is designed with an isolation relay that electrically isolates the park disk from the power source during running modes, capturing and suppressing EMI emissions before they can radiate through external wires, and connects power to the park disk only during the park mode to dynamically park the motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the park disk is continuously connected to power during operation, then the motor can dynamically park the windshield wipers, but electromagnetic interference emissions increase
Solution Approach 1:
The isolation relay is configured to disconnect power to the park disk before the motor completes its rotation to the park position. This preliminary disconnection prevents the generation of electromagnetic interference pulses that would occur if power remained connected throughout the entire operation cycle, while still allowing the motor to complete its parking function.
Solution Approach 2:
An isolation relay is introduced as an intermediary component between the power source and the park disk. This relay acts as a controlled switch that can disconnect the park disk from power during specific phases of motor operation, thereby eliminating the harmful electromagnetic emissions while preserving the dynamic park capability when needed.
2Object-generated harmful factors
If the isolation relay disconnects power early, then electromagnetic emissions are reduced, but the motor may not complete full parking operation
Solution Approach 1:
The isolation relay is timed to disconnect power at the optimal moment - after the motor has sufficient momentum to complete its rotation to the park position but before electromagnetic interference pulses would be generated. This preliminary disconnection strategy ensures both emission reduction and reliable parking operation completion.
Solution Approach 2:
The system uses the motor's existing mechanical momentum and inertia to complete the parking rotation after power disconnection. Rather than relying on continuous electrical power, the design leverages the mechanical energy already stored in the rotating system to ensure reliable completion of the parking 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 significantly reduces or eliminates EMI emissions, protecting sensitive electronic devices and preventing detection of military vehicles, while meeting industry standards like U.S. military standard MIL-STD-461F.
Implementation Method 1
The motor is designed with an isolation relay that electrically isolates the park disk from the power source during running modes, capturing and suppressing EMI emissions before they can radiate through external wires
Data Source
AI summary
Motors and method of operation thereof operable in a running mode wherein the motor operates at a constant speed, and operable in a park mode wherein the motor is dynamically parked. The motor is housed within a housing and includes a rotating park disk configured to cause the motor to dynamically park. A park wire electrically couples the park disk to a switch configured to selectively switch the motor between the running mode and the park mode, and a power wire electrically couples the park disk to a power source. The park disk is electrically isolated from the power source during operation of the motor in the running mode and the park wire is electrically connected to the power source through the park disk and the power wire during operation of the motor in the park mode.