Single Power Stage Control for Synchronized Lawnmower Blade Motors
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Solution Overview
Problem
Existing electric lawnmowers with multiple brushless motors require separate motor controllers for each blade, leading to high costs and unnecessary precision in speed control, as each blade may have different loading conditions, necessitating a more efficient and cost-effective solution for simultaneous speed control and overload protection.
Innovation Solution
A single multi-phase power stage with a controller that uses speed feedback signals from each motor to synchronize blade speeds, ramps up motor power sequencing, and shuts down all motors if any blade encounters excessive torque, ensuring all blades operate at the same speed and preventing damage from overload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate motor controllers are used for each blade motor, then each blade can be controlled independently, but the system cost increases and precision is unnecessary
Solution Approach 1:
The patent combines multiple separate motor controllers into a single multi-phase power stage that can control multiple brushless motors simultaneously. This single controller uses feedback signals from each motor to synchronize blade speeds while reducing system cost and complexity by eliminating the need for multiple independent power stages.
Solution Approach 2:
The single multi-phase power stage is designed to perform multiple functions: it controls multiple blade motors independently through a unified control architecture, provides speed synchronization across all blades, and offers overload protection for the entire system. This universal controller replaces what would traditionally require multiple specialized controllers.
2Device complexity
If a single power stage controls multiple motors, then cost is reduced, but speed synchronization and overload protection must be achieved
Solution Approach 1:
The system employs feedback signals from each brushless motor that are fed into the single controller. This feedback mechanism enables the controller to monitor the operational status of each motor, synchronize blade speeds by adjusting power distribution, and detect overload conditions to shut down the system when necessary, thereby maintaining reliability despite using a single power stage.
3Productivity
If precise speed control is applied to each blade, then each blade operates optimally, but precision is unnecessary and cost increases
Solution Approach 1:
Instead of applying full precision speed control to each individual blade, the system uses a single controller that provides sufficient speed synchronization across all blades through feedback-based power distribution. This partial control approach achieves adequate cutting performance without the unnecessary precision and cost of individual blade control systems.
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 reduces costs by using a single power stage for multiple motors, ensures all blades spin at the same speed, and protects the system from overload by synchronizing speed and torque across all motors, maintaining efficient cutting performance while preventing damage.
Implementation Method 1
a controller switches currents through motor windings to produce rotating magnetic fields to lead the rotor to rotate
Data Source
AI summary
An apparatus for motor control of a lawnmower includes multiple blade motors, a logic circuit and a power circuit. The plurality of blade motors are coupled to the lawnmower and configured for cutting vegetation. The logic circuit configured to receive a feedback signal from each of the plurality of blade motors and generate an output signal. The power circuit is configured to drive each of the plurality of blade motors simultaneously in response to the output signal such that the speed of all of the plurality of blade motors is lowered when the feedback signal indicates that one of the plurality of blade motors has encountered an obstruction, clog, or another type of high load.