Active Pre-Charge Controller for Constant-Current HV Battery Startup
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Solution Overview
Problem
Current methods for pre-charging high voltage capacitors in battery systems are slow, bulky, and costly, relying on resistors and contactors that cause inrush currents and inefficiencies.
Innovation Solution
An integrated circuit (IC) with a pre-charging controller that manages capacitive loads using a programmable current control module, smart gate driver, and safety monitoring to maintain constant charging current, detect over/undervoltage, and indicate charge completion, enhancing safety and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resistor is used in series with a contactor to pre-charge the bulk capacitor, then the inrush current is limited, but the charging process becomes slow and the system becomes bulky and costly
Solution Approach 1:
The patent replaces the mechanical contactor and passive resistor system with an electronic switch (MOSFET or IGBT) controlled by a microcontroller. This active electronic control system substitutes the mechanical switching and passive resistance-based current limiting, enabling precise control of charging current while achieving faster charging speeds without the bulk and cost of traditional mechanical components.
Solution Approach 2:
The patent dynamically changes the resistance parameter during the charging process by using a controlled switch that transitions from a high-resistance state (limiting inrush current) to a low-resistance state (enabling fast charging). The microcontroller monitors the capacitor voltage and adjusts the switch control accordingly, changing the effective resistance parameter over time to optimize both safety and charging speed.
2Reliability
If a resistor is used in series with a contactor for pre-charging, then the system provides basic protection, but the system becomes bulky and costly
Solution Approach 1:
The patent merges multiple functions into a single integrated control system. The microcontroller combines the functions of current limiting control, charging monitoring, protection detection, and charge completion signaling that were previously distributed across separate components (resistor, contactor, protection circuits). This integration reduces system size and component count while maintaining comprehensive protection capabilities.
Solution Approach 2:
The controlled switch (MOSFET/IGBT) serves multiple functions: it acts as the main charging switch, provides current limiting during startup, enables protection against overvoltage and other faults through microcontroller monitoring, and signals charge completion. This multi-functional component replaces the need for separate dedicated components for each function, reducing overall system complexity and cost.
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 IC reduces charging time by up to 60% and ensures safe, efficient pre-charging with advanced safety features, suitable for high voltage battery systems in automotive applications.
Implementation Method 1
configuring an inductor current to maintain constant charging current based on feedback from the programmable current control module
Implementation Method 2
driving one or more high voltage field-effect transistors (FETs) based on one or more control signals from the pre-charging controller
Data Source
AI summary
Example implementations include a method, apparatus and integrated circuit (IC) for active pre-charging a battery system. The IC may include a pre-charging controller configured to manage pre-charging of a capacitive load. The IC may include a programmable current control module configured to maintain constant charging current based on one or more parameters from the pre-charging controller. The IC may include a smart gate driver configured to drive one or more high voltage field-effect transistors (FETs) based on one or more control signals from the pre-charging controller. The IC may include a boundary mode controller configured to configure inductor current to maintain constant charging current. The IC may include a safety monitoring module configured to detect an overvoltage or undervoltage state based on system voltage monitoring. The IC may include a timing module configured to indicate a charge completion following a defined charge time.