Brushless Motor Control Unit for Speed-Dependent Electronic Braking
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Solution Overview
Problem
Conventional brushed motors are less durable and less efficient due to mechanical wear and friction, and electronic braking of brushless motors is challenging, especially when the motor is switched off, as the controller is automatically deactivated, leading to difficulties in synchronizing rotor rotation with sequential commutation.
Innovation Solution
A control unit for brushless motors that remains active for a speed-dependent time after detecting motor stoppage via a Hall sensor, initiating electronic braking by controlling power switches and MOSFETs to ensure reliable and cost-effective braking, with a programmable microcontroller managing the braking process and energy storage for sustained operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the controller is automatically turned off when the motor-driven device is turned off, then power consumption is reduced, but electronic braking cannot be performed and rotor synchronization becomes difficult
Solution Approach 1:
The controller remains in a standby state after the device is turned off, performing preliminary electronic braking action before complete shutdown. This allows the rotor to be synchronized and braked electronically before the controller fully deactivates, resolving the contradiction between power consumption and braking reliability.
2Device complexity
If brushed motors are used for mechanical commutation, then device complexity is reduced, but mechanical wear increases and service life decreases
Solution Approach 1:
The patent replaces the mechanical brush and commutator system with an electronic commutation system using MOSFETs and a control unit. This substitution eliminates mechanical wear from brushes while providing reliable electronic commutation, resolving the contradiction between device complexity and service life.
3Reliability
If brushless motors are used for electronic commutation, then service life is improved, but controller deactivation during braking becomes problematic
Solution Approach 1:
The controller dynamically adjusts its operational state, transitioning from active control to standby mode after device shutdown. This dynamic state change allows the controller to remain functional long enough to complete electronic braking and rotor synchronization, then fully deactivate, resolving the contradiction between service life improvement and braking control ease.
4Reliability
If the controller remains active for a speed-dependent time after device switch-off, then electronic braking reliability is improved, but power consumption increases
Solution Approach 1:
The controller uses speed-dependent timing parameters, adjusting the standby duration based on motor speed. At higher speeds, the controller remains active longer to ensure complete braking; at lower speeds, the standby time is reduced. This parameter adaptation resolves the contradiction between braking reliability and power consumption by optimizing the balance based on actual operating conditions.
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 control unit ensures reliable electronic braking of brushless motors by maintaining an active state until motor standstill is confirmed, reducing mechanical wear and improving efficiency by distributing the braking current effectively through MOSFETs, thereby enhancing motor durability and energy efficiency.
Implementation Method 1
detecting a Hall sensor signal state indicative of the motor being completely stopped
Implementation Method 2
When current is applied to a winding, the resulting current in the winding creates a magnetic field that couples to the rotor
Implementation Method 3
The magnetic field associated with the permanent magnet in the rotor assembly attempts to align with the magnetic field generated by the stator, resulting in rotational movement of the rotor
Data Source
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AI summary
The invention relates to a control unit (1) for a motorized device (10) comprising: a brushless motor (20), a power supply (30), an operating unit (40), which can be activated by a user, wherein the control unit (1) is designed at least for controlling the commutation of the motor (20) by a plurality of circuit breakers (12, 13, 14, 15, 16, 17) connected to the power supply, and for initiating an electronic (i.e. in particular non-mechanical) braking of the motor, wherein the control unit (1) is deactivated, i.e. switched off, for a rotational speed-dependent duration to by means of a position sensor (50) and is held until then in an active switched-on operating state and, dependent thereon, a control means (60) is provided then to initiate, under automatic control, the shutdown of the device (10).