Transformer-Based Pre-Charge Circuit for Battery Systems
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Solution Overview
Problem
Conventional pre-charge circuits for batteries suffer from overheating issues due to repeated pre-charging of smoothing capacitors and wastage of electrical energy, which can damage components and reduce efficiency.
Innovation Solution
A power supply circuit that pre-charges smoothing capacitors and charges batteries using energy from each other while maintaining insulation, employing a transformer and switching circuits controlled by a switch controller to manage energy transfer efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pre-charge resistor is used to pre-charge the smoothing capacitor before the main contactor is turned on, then the voltage difference between the battery and the electrical load is reduced, but the pre-charge resistor overheats when the smoothing capacitor is pre-charged a very large number of times in a short time
Solution Approach 1:
The patent introduces a transformer as an intermediary device between the battery and the smoothing capacitor. The transformer enables indirect energy transfer through magnetic coupling, avoiding direct current flow through a resistive pre-charge component. This mediator allows the smoothing capacitor to be charged without subjecting a resistor to excessive heat generation during repeated pre-charging operations.
2Ease of operation
If a pre-charge resistor is used to pre-charge the smoothing capacitor, then the smoothing capacitor can be charged before main contactor operation, but the electrical energy stored in the smoothing capacitor through pre-charging is wasted and cannot be used to charge the battery
Solution Approach 1:
The patent enables the recovery of energy that would otherwise be discarded. The transformer allows bidirectional energy transfer: during pre-charging, the smoothing capacitor is charged from the battery; subsequently, the charged smoothing capacitor can discharge energy back to the battery through the transformer. This recovers the energy that would have been wasted in conventional pre-charge circuits.
Solution Approach 2:
The transformer provides multi-functionality by enabling both pre-charging of the smoothing capacitor and subsequent charging of the battery from the smoothing capacitor. This single device serves multiple purposes: it acts as an isolation barrier, enables controlled energy transfer in both directions, and eliminates the need for separate pre-charge and energy recovery circuits.
3Speed
If the main contactor is turned on when a difference between the voltage of the battery and the voltage of the smoothing capacitor is very large, then the electrical connection is established quickly, but a very high current instantaneously flows through the main contactor causing damage
Solution Approach 1:
The patent performs preliminary action by pre-charging the smoothing capacitor through the transformer before the main contactor is closed. This preliminary energy transfer equalizes the voltage difference between the battery and the electrical load, ensuring that when the main contactor closes, the voltage differential is minimal and no damaging current surge occurs.
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
Enables pre-charging of smoothing capacitors and charging of batteries without overheating and energy wastage, improving the performance and longevity of battery management systems and packs.
Implementation Method 1
a transformer and switching circuits controlled by a switch controller to manage energy transfer efficiently
Data Source
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AI summary
Provided is a power supply circuit for energy transfer between a battery and a smoothing capacitor, a battery management system and a battery pack. The power supply circuit includes a transformer including a first winding and a second winding, a first switching circuit including a first switch connected in series to the first winding, and connected in parallel to the battery together with the first winding, a second switching circuit including a second switch connected in series to the second winding, and connected in parallel to the smoothing capacitor together with the second winding, and a switch controller. To pre-charge the smoothing capacitor, the switch controller is configured to perform a first operation of turning on the first switch and turning off the second switch, and subsequently perform a second operation of turning off the first switch and turning on the second switch.