Latching Relay Power Management for Voltage Transient Protection
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Solution Overview
Problem
Electrical systems in internal combustion engine-based motor vehicles face damage from excessive voltage transients and sustained battery discharge, leading to reduced service life and compromised starting capabilities due to alternator voltage regulator failures and high charging rates.
Innovation Solution
A motor vehicle electrical power management system that uses latching relays to monitor and control current and voltage, selectively shedding loads based on measured values to protect the battery and loads from excessive voltage, current surges, and prolonged discharge, with mandatory and optional loads prioritized for power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If alternator voltage regulators are used to control voltage output, then power distribution is improved, but excessive voltage transients can damage loads and reduce service life
Solution Approach 1:
A microcontroller unit acts as an intermediary between the alternator voltage regulator and the power distribution system. The MCU monitors voltage levels and controls latching relays to disconnect loads when voltage exceeds safe thresholds, preventing damage while maintaining normal power distribution during acceptable conditions.
Solution Approach 2:
The system continuously monitors voltage levels through voltage sensing circuitry connected to the MCU. When voltage exceeds predetermined thresholds, the MCU receives feedback and automatically opens latching relays to protect loads. The system also monitors current and provides feedback for comprehensive power management.
2Duration of action of moving object
If battery operates alone to support loads, then power supply continuity is maintained, but battery state of charge decreases and service life is reduced
Solution Approach 1:
The MCU continuously monitors battery voltage and current to determine state of charge. When the battery is operating alone and voltage drops below thresholds indicating low state of charge, the system receives feedback and automatically sheds non-critical loads through latching relays, preserving battery charge for essential functions and extending battery service life.
Solution Approach 2:
The system segments loads into critical and non-critical categories using latching relays. When battery power alone must be maintained, non-critical loads are automatically disconnected while critical loads remain powered, allowing the battery to sustain essential vehicle functions without complete discharge.
3Reliability
If latching relays are used to control load disconnection, then load protection is improved, but system complexity increases
Solution Approach 1:
A microcontroller unit serves as an intelligent intermediary that centralizes the control logic for multiple latching relays. The MCU processes sensor inputs and automatically actuates the appropriate relays based on monitored conditions, replacing complex hard-wired control circuits with programmable logic that simplifies system design and maintenance.
Solution Approach 2:
The microcontroller unit performs multiple functions: monitoring voltage, monitoring current, controlling latching relays, and implementing power management strategies. This single multi-functional component replaces what would otherwise require separate dedicated circuits for each function, reducing overall system complexity despite the addition of the MCU itself.
Data Source
AI summary
The loads of a vehicle electrical system are connected to a power distribution bus through a first or through first and second latching relays. A set of vehicle mandatory loads are connected to an output side of the first latching relay to be cut off from the power distribution bus upon opening of the first latching relay. A set of vehicle optional loads are connected to an output side of the second latching relay to be cut off from the power distribution bus upon opening of the first latching relay or the second latching relay. Opening and closing of the first and second latching relays depends of the values for the measured current and measured voltage. Among factors relating to opening and closing of the first and second latching relays are measured voltage exceeding a voltage high threshold, in which case the first latching relay opens, measured voltage falling below a low voltage threshold in which case the second latching relay opens while the first latching relay remains closed and a positive current transient exceeding a minimum threshold, which opens the first latching relay.