Hybrid Powertrain Control System for Battery Voltage Balancing
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Solution Overview
Problem
The initiation and de-initiation of electrical systems in hybrid-electric powertrains can cause rapid uncontrolled energy flow, damaging components, and voltage imbalances in battery cells can lead to premature failure and reduced battery life, as existing battery management systems either drain batteries when shut off or struggle to balance voltages during varying loads.
Innovation Solution
A control system that includes a master controller and secondary controllers to manage the initiation and de-initiation of the hybrid-electric powertrain, performing high-voltage battery pack cell voltage balancing tests, dynamically balancing voltages during operation, and controlling high-voltage isolation contactors to prevent damage and ensure stable energy flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-voltage isolation contactors are transitioned from open state to closed state upon activation, then electrical systems can be initiated quickly, but rapid uncontrolled free flow of electrical energy may damage system components
Solution Approach 1:
The control system performs preliminary actions before closing the high-voltage isolation contactors: it detects the state of charge of battery cells, balances voltage differences between cells, and activates pre-charge contactors with resistive elements to limit inrush current. These preliminary actions prevent rapid uncontrolled energy flow when the main contactors close, resolving the contradiction between quick initiation and component protection.
Solution Approach 2:
Pre-charge contactors with resistive elements are introduced as intermediary components between the battery pack and the main isolation contactors. These intermediaries limit the rate of energy flow during initiation, preventing damage to power conversion equipment while still allowing the system to start up. The resistive elements act as mediators that control the transition of electrical energy safely.
2Stability of the object's composition
If battery management systems balance voltage after vehicle shutdown, then battery cell voltage can be balanced, but battery packs may be drained to levels that prevent vehicle starting
Solution Approach 1:
The control system performs voltage balancing as a preliminary action during vehicle operation, specifically during idle periods when the vehicle is running but not under load. By detecting voltage differences between battery cells and redistributing charge during these idle periods, the system maintains voltage balance without draining the battery to dangerous levels, thus preserving starting capability while achieving voltage equilibrium.
Solution Approach 2:
The battery management system dynamically adjusts its operation based on vehicle state. During operation, it continuously monitors cell voltages and performs balancing when conditions are favorable (idle periods). During shutdown, it avoids aggressive balancing that would drain the battery. This dynamic adaptation allows the system to maintain voltage balance while preserving sufficient charge for vehicle starting.
3Measurement precision
If battery management systems operate actively during powertrain operation, then real-time monitoring is possible, but it becomes increasingly difficult to balance battery packs as electric loads constantly vary voltage
Solution Approach 1:
The control system employs periodic action by performing voltage balancing during idle periods when the vehicle is running but not under load. During these idle periods, electric loads are minimized or zero, creating stable conditions for effective voltage balancing. The system periodically checks cell voltages and performs balancing operations when conditions are favorable, rather than attempting continuous balancing under varying loads. This periodic approach maintains measurement precision while achieving voltage balance.
Solution Approach 2:
The system performs voltage balancing as a preliminary action during idle periods before the next load cycle begins. By detecting and correcting voltage imbalances during these quiet periods, the system prepares the battery pack for upcoming load demands. This preliminary balancing ensures that when loads are applied, the battery cells are already in a more balanced state, improving overall system performance without requiring continuous balancing during load variations.
Data Source
AI summary
A method of operating a vehicle with hybrid-electric powertrain having an engine, a generator, and a battery is provided. A vehicle start input signal is received from an operator interface. A master controller initiates after receiving input from the operator interface. A secondary controller initiates after starting initiation of the master controller. A battery pack cell voltage balancing test is performed utilizing the master controller. Voltage within the battery pack cells is balanced based upon the balancing test. An isolation contactor closes after balancing the voltage within the battery pack. A signal from the master controller to the secondary controller to begin operation is generated after closing the isolation contactor. Alternately, voltage within the battery pack cells based upon results of the balancing test may take place dynamically during vehicle operation after closure of the isolation contactor.