Redundant Brake Inverter EMI Filtering for Conducted Noise Reduction
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Solution Overview
Problem
Existing brake control units with redundant circuitry face challenges in effectively suppressing noise from inverters, which can affect other devices connected to the power supply, and require costly EMI-filters to comply with electromagnetic compliance requirements.
Innovation Solution
The improved brake control unit incorporates a primary and secondary control branch with EMI-filters, where the secondary EMI-filter is connected to the power supply even in normal operational mode, providing additional noise reduction without the need for identical configurations, and allows the secondary inverter to be deactivated, reducing noise levels further.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant brake control unit with primary and secondary control branches is implemented, then reliability is improved, but noise suppression becomes more difficult and device complexity increases
Solution Approach 1:
The patent combines the noise suppression functions of both primary and secondary EMI-filters to work together during normal operation. The secondary EMI-filter, while not strictly necessary for redundancy, provides additional noise filtering capability when activated alongside the primary EMI-filter, achieving better overall noise suppression than either filter alone.
Solution Approach 2:
The secondary control branch is designed with dual functionality: it serves as a backup for reliability while also providing additional noise suppression capability when activated during normal operation. This multi-functionality allows the same hardware to address both reliability and noise suppression requirements.
2Object-affected harmful factors
If EMI-filters are added to suppress noise from inverters, then electromagnetic compliance is improved, but hardware cost increases
Solution Approach 1:
The patent implements a configuration where the secondary EMI-filter is partially utilized - it is present in the system but only fully activated during specific operational modes. During normal operation with the primary branch, the secondary EMI-filter provides enhanced noise suppression. During backup operation with the secondary branch, only the secondary EMI-filter is active. This partial utilization reduces the overall hardware burden compared to having both filters fully active at all times.
3Object-generated harmful factors
If the secondary EMI-filter is connected to the power supply in normal operational mode, then noise reduction is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic control of the secondary EMI-filter connection to the power supply based on operational mode. During normal operation with the primary control branch, the secondary EMI-filter is connected to provide enhanced noise suppression. When switching to backup operation with the secondary control branch, the system dynamically reconfigures to use only the secondary EMI-filter. This dynamic adaptation optimizes the balance between noise reduction and power consumption based on current operational requirements.
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 configuration achieves substantial noise reduction with modest hardware costs, ensuring reliable operation even when the secondary control branch is not healthy, and allows the vehicle to continue functioning temporarily, urging the driver to seek repairs.
Implementation Method 1
The EMI-filter suppresses a backpropagation of noise originating from the invertor and actuator to the power supply
Data Source
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AI summary
A brake control unit (50) is provided to drive a brake actuator. The brake control unit comprises a primary control branch (510) with a primary inverter (512) and a primary EMI-filter (517) and a secondary control branch (520) with a secondary inverter (522) and a secondary EMI-filter (527). The primary control branch is configured to provide drive signals (D10) to the brake actuator in a normal operational mode. The secondary control branch (510) is configured to provide drive signals to the brake actuator in the at least a second operational mode. During the first, normal operational mode, both the primary EMI-filter and the secondary EMI-filter are coupled with their input to the power source. Therewith an improved reduction of conducted electromagnetic interference is achieved.