Electric Tool Power Circuit With Direct Supply Path Motor Control
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Solution Overview
Problem
Conventional electric tools require expensive DC to DC converters, which occupy space and have poor energy conversion efficiency.
Innovation Solution
An electric tool design that eliminates the need for a DC-DC converter by incorporating a charging and discharging control circuit that calculates an upper limit of load current based on input and load currents, allowing direct power supply and motor control, and supports various charging modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DC to DC converter is used in conventional electric tools, then power conversion function is achieved, but cost increases and device space is occupied
Solution Approach 1:
The patent extracts the DC-DC converter from the electric tool system and relocates it to the power adapter. This allows the electric tool to eliminate the expensive and space-consuming DC-DC converter while still achieving efficient power conversion. The power adapter assumes the power conversion function, enabling the electric tool to use a simpler direct power supply path.
Solution Approach 2:
The power adapter serves as an intermediary device that performs power conversion before delivering power to the electric tool. By placing the DC-DC converter in the power adapter rather than in the electric tool, the system achieves power conversion functionality while reducing the complexity and cost of the electric tool itself.
2Reliability
If a DC to DC converter is used in conventional electric tools, then power conversion is achieved, but energy conversion efficiency deteriorates
Solution Approach 1:
By extracting the DC-DC converter from the electric tool and placing it in the power adapter, the patent enables more efficient power conversion. The power adapter can optimize the conversion process for the specific battery pack being used, reducing energy losses that would occur with a generic DC-DC converter in the electric tool.
3Device complexity
If direct power supply path is used without DC-DC converter, then cost and space are reduced, but power management capability deteriorates
Solution Approach 1:
The power adapter acts as an intermediary that provides sophisticated power management capabilities to the electric tool through the direct power supply path. The charging and discharging control circuit in the power adapter handles battery management, charging control, and power optimization, enabling the electric tool to benefit from advanced power management without incorporating complex hardware.
Solution Approach 2:
The system implements feedback control through the charging and discharging control circuit, which monitors battery status and adjusts power delivery accordingly. The control circuit calculates upper limits of load current based on battery state, ensuring safe and efficient operation while maintaining adaptability to different battery packs and power adapters.
Data Source
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AI summary
An electric tool is powered by a battery. An electric tool includes a motor, a charging and discharging control circuit and a motor control circuit. Charging and discharging control circuit is configured to couple to a power adapter. Charging and discharging control circuit includes a direct power supply path connected to the power adapter and battery, and is configured to detect an input current from power adapter and a first load current flowing to battery and to calculate an upper limit of a second load current that can be provided to motor according to a difference between the input current and the first load current. Motor control circuit is coupled between charging and discharging control circuit and motor, and is configured to control a speed or a torque of motor according to the upper limit of second load current.