Battery Pack Current Path Switching for Compact Tool Interfaces
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Solution Overview
Problem
Existing battery packs for hand-held power tools face challenges in maintaining safety while maintaining a compact interface configuration, as they struggle to separately control charge and discharge currents without modifying the interface geometry.
Innovation Solution
The battery pack incorporates a configuration with at least partially separated charge and discharge current paths, utilizing a first switching element to switch between these paths, and includes current limiters like MOSFETs to safely manage currents, thereby avoiding the need for an anti-serial MOSFET circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the same contact elements are used for both charging and discharging to maintain compact interface configuration, then the interface remains compact and compatible with predecessor models, but separate control of charge and discharge currents becomes difficult without additional components
Solution Approach 1:
The patent segments the current control by separating charge and discharge current paths with different switching elements. The charge current path includes a first switching element while the discharge current path includes a second switching element, allowing independent control of each current direction despite using the same physical contact elements for both functions.
Solution Approach 2:
The patent implements dynamic control by using switching elements that can change the electrical connectivity state based on operational mode. The switching elements enable the system to dynamically route current through appropriate paths during charging versus discharging, adapting the circuit configuration to the required function while maintaining the same mechanical interface.
2Ease of operation
If MOSFETs are used for current control, then current switching capability is improved, but parasitic body diodes prevent blocking of both charge and discharge currents simultaneously
Solution Approach 1:
The patent merges the advantages of MOSFETs with anti-serial diodes in a hybrid current control circuit. The MOSFET provides low-resistance current conduction when active, while the anti-serial diode configuration ensures that both charge and discharge currents can be blocked when needed, compensating for the parasitic body diode limitation.
Solution Approach 2:
The patent creates a composite current control mechanism combining different electrical components (MOSFETs and diodes) with complementary characteristics. This composite approach leverages the high current-carrying capacity and low on-resistance of MOSFETs while using diodes to provide bidirectional current blocking capability that MOSFETs alone cannot achieve.
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
This solution enhances safety by allowing separate control of charge and discharge currents, reduces costs and power loss by eliminating unnecessary components, and maintains compatibility with existing equipment by retaining a minimal interface configuration.
Implementation Method 1
current limiters like MOSFETs to safely manage currents
Implementation Method 2
MOSFETs have a parasitic body diode, which is why only one current direction can be blocked at a time
Data Source
AI summary
The disclosure relates to a battery back for a hand-held power tool comprising a battery pack housing. An interface of the battery pack housing has contact elements for contacting corresponding counter contact elements on the hand-held power tool and/or the charging device. A battery pack electronics system comprises a charge current path and a discharge current path. The charge current path is designed to connect the contact elements to the battery cell during a charging of the at least one battery cell, while the discharge current path is designed to connect the contact elements to the battery cell during a discharging of the at least one battery cell. The charge current path and the discharge current path are at least partially electrically separate from one another. The battery pack also comprises a first switch element for switching between at least the charge current path and the discharge current path.