Solid-State Electronic Brake for Universal Motor
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Solution Overview
Problem
Conventional electronic brake modules for universal electric motors in power tools are complex and costly due to the use of multiple mechanical switches or relays, which increases the number of switch contacts and space requirements.
Innovation Solution
A power system with an electronic brake module that employs a solid-state semiconductor switch, diodes, and a controller to manage the braking process, reducing the need for multiple switches by using a single semiconductor switch to handle both field and armature currents, and optimizing braking time and torque through phase-controlled switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electronic brake modules use multiple mechanical switches or relays for braking, then braking function is achieved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical switches and relays with solid-state electronic components including a triac, diodes, and a microcontroller. This substitution eliminates mechanical moving parts while achieving the same braking function through electronic control of the motor field windings, thereby reducing device complexity and maintenance requirements.
Solution Approach 2:
The microcontroller serves multiple functions: it controls the triac for phase-angle control during normal operation, initiates braking by triggering the triac in reverse sequence, and monitors motor operation. This multi-functionality consolidates what would traditionally require separate mechanical switches and relays into a single integrated control unit, reducing overall circuit complexity.
2Reliability
If multiple mechanical switches or relays are used in brake modules, then braking control is achieved, but manufacturing cost increases
Solution Approach 1:
By replacing expensive mechanical switches and relays with solid-state components (triac, diodes, microcontroller), the patent reduces manufacturing costs. Solid-state components have fewer moving parts, require less assembly, and have longer lifespans, making them more cost-effective for mass production while maintaining reliable braking control.
Solution Approach 2:
The patent controls braking by changing the electrical parameters (phase angle, current direction, timing) through electronic control rather than using multiple mechanical switches. The microcontroller adjusts the firing angle of the triac and controls the timing of diode activation to achieve precise braking control, replacing what would traditionally require multiple discrete switching components.
3Reliability
If conventional brake modules use multiple switches, then braking function is achieved, but space requirements increase
Solution Approach 1:
The patent merges the functions of multiple mechanical switches and relays into a single integrated circuit board containing a triac, diodes, and a microcontroller. This consolidation reduces the physical space required for the braking circuit while maintaining all necessary braking functions through electronic control of the motor field windings.
Solution Approach 2:
Replacing mechanical switches and relays with solid-state electronic components significantly reduces the space required for the braking circuit. Solid-state components are smaller, have no moving parts, and can be mounted on compact circuit boards, thereby reducing the overall footprint of the power tool while maintaining reliable braking function.
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 solution minimizes switch contacts, reduces costs, and provides efficient braking by controlling the semiconductor switch and phase-controlled triac to achieve smooth and controlled motor braking, reducing the complexity and cost of the braking circuit.
Implementation Method 1
an electronic brake module configured to generate a braking force to stop the motor when the switch is opened
Implementation Method 2
use the current generated by the back electromotive force (EMF) of the motor armature to slow down the armature
Implementation Method 3
a phase-controlled triac arranged in series with the field windings on the power line to control the supply of AC power from the terminals to the motor
Data Source
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AI summary
A power system is provided comprising an electric universal motor including an armature rotatable coupled to an armature shaft and a commutator disposed on an armature shaft, a pair of brushes engaging the commutator, and a field having at least two field windings electrically coupled in series with the pair of brushes. The power system includes a power line having two terminals arranged to provide alternating-current (AC) power from a power supply, and a power switch provided in series with the field windings on a power line to provide AC power from the terminals to the motor when the power switch is closed. An electronic brake module is provided in the power system and configured to generate a braking force to stop the motor when the switch is opened, the electronic brake module comprising: a solid-state semiconductor switch arranged across the motor armature and the pair of brushes, a first diode arranged between a first node of the power line and the semiconductor switch, and a second diode arranged between a second node of the power line and the semiconductor switch, wherein the first node is arranged between one of the terminals and the power switch, and the second node is arranged between the power switch and the armature. A controller is provided in the power system and configured to initiate a braking mode of operation to close the semiconductor switch when the power switch is opened.