HV Battery Pack Discharge Using ECU-Controlled Resistive Load
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Solution Overview
Problem
Existing strategies for discharging high-voltage battery packs in electrified powertrain systems are slow, manually intensive, and imprecise, particularly during manufacturing or maintenance scenarios where a precise low state of charge is required before shipment.
Innovation Solution
An automated system using a resistive load and an electronic control unit (ECU) that selectively adjusts electronic control signals based on reported state of charge and auxiliary voltage to control the output state of the resistive load, including fan-and-heater elements, to discharge the battery pack efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing manual discharge strategies are used, then the battery pack can be discharged, but the process is slow and manually intensive
Solution Approach 1:
The system enables the battery pack to discharge automatically through self-monitoring and self-regulation. The control unit continuously monitors the state of charge and automatically controls the resistive load to maintain the desired discharge rate without manual intervention, allowing the system to service itself throughout the discharge process.
Solution Approach 2:
The system implements closed-loop feedback control where the control unit continuously monitors the battery's state of charge and adjusts the resistive load accordingly. This feedback mechanism ensures the battery discharges at the optimal rate while maintaining safety parameters, eliminating the need for manual monitoring and adjustment.
2Measurement precision
If existing discharge methods are used, then the battery can be discharged, but the process is imprecise
Solution Approach 1:
The control unit continuously monitors the battery's state of charge through feedback from monitoring circuits and dynamically adjusts the resistive load to maintain precise control over the discharge process. This ensures the battery reaches the target state of charge threshold with high accuracy, preventing both over-discharge and under-discharge conditions.
Solution Approach 2:
The system dynamically adjusts the resistive load based on real-time battery conditions. As the battery state of charge changes, the control unit modifies the load resistance to maintain optimal discharge characteristics, ensuring precise control throughout the varying discharge process rather than using a fixed discharge rate.
3Reliability
If high-voltage battery is isolated from low-voltage bus, then safety is improved, but discharge control becomes more complex
Solution Approach 1:
The system introduces a controlled intermediary pathway through the resistive load and control unit that bridges the high-voltage and low-voltage systems. This intermediary mechanism allows safe energy dissipation from the high-voltage battery while maintaining electrical isolation, enabling discharge control without compromising the voltage isolation safety barrier.
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
The system provides precise and efficient discharge of high-voltage battery packs by optimizing the discharge rate through closed-loop diagnostics and feedback control, reducing the state of charge to a specified level without manual intervention.
Implementation Method 1
A non-limiting exemplary embodiment of the electrical system includes an electric vehicle, e.g., an electrified motor vehicle having road wheels and one or more electric traction motors energized by the battery pack
Implementation Method 2
The resistive load may include one or more fan-and-heater elements, with each of the fan-and-heater elements being operable for intaking and heating ambient airflow from a surrounding ambient environment
Data Source
AI summary
A device for discharging a high-voltage (“HV”) battery pack in an electrical system having a low-voltage (“LV”) bus and a high-voltage (“HV”) bus includes a resistive load and an electronic control unit (“ECU”). The ECU transmits electronic control signals to the resistive load to change an output state of the resistive load. As part of a related method, the ECU receives a state of charge (“SOC”) of the battery pack and an auxiliary voltage level of the LV bus. The ECU then selectively adjusts the electronic control signals in response to the SOC and auxiliary voltage level to optimize the output state of the resistive load. This continues until the SOC is within a specified SOC range.