Mechanical Commutator Motor Control for Brush Sparking Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Mechanical commutators in electric motors experience brush wear due to spark erosion, noise, and electromagnetic emissions, which are not effectively addressed by existing control methods.
Innovation Solution
A method controlling an electric motor with a mechanical commutator using a pulse-modulated supply voltage signal, where the modulation signal is in phase with commutation times to reduce the supply voltage to essentially zero volts, minimizing spark formation and brush wear, employing techniques like pulse width modulation, pulse density modulation, or other modulation methods without or with the aid of sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a mechanical commutator with brushes is used in an electric motor, then cost-effective motor construction is achieved, but brush wear due to spark erosion occurs and noise and electromagnetic emissions are generated
Solution Approach 1:
The supply voltage is periodically reduced to essentially zero volts at commutation times using pulse width modulation, creating a periodic on-off action that suppresses sparks only when needed during commutation events while maintaining normal operation between commutations
Solution Approach 2:
The supply voltage parameter is dynamically changed by modulating it to essentially zero volts at commutation times, transforming the voltage from a continuous value to a time-varying parameter that adapts to the commutation state to minimize erosion
2Ease of manufacture
If a mechanical commutator with brushes is used in an electric motor, then cost-effective motor construction is achieved, but noise and electromagnetic emissions are generated
Solution Approach 1:
The supply voltage is periodically suppressed at commutation times using pulse width modulation, creating intermittent voltage reduction that targets spark generation events specifically, thereby reducing noise and electromagnetic emissions only when mechanical commutation occurs
Solution Approach 2:
The supply voltage parameter is dynamically modulated to essentially zero volts synchronized with commutation times, changing the electrical parameter to minimize arc formation and its associated noise and electromagnetic interference
3Reliability
If the supply voltage is reduced to essentially zero volts at commutation times, then brush wear and sparking are reduced, but the average supply voltage must be maintained for motor operation
Solution Approach 1:
The voltage suppression is applied periodically only during brief commutation intervals rather than continuously, allowing the average voltage to remain sufficient for motor operation while providing protective voltage reduction exactly when sparks occur
Solution Approach 2:
The voltage is reduced to essentially zero volts (excessive reduction) but only for brief periods during commutation, not continuously, so that the partial time-averaged voltage remains adequate for normal motor power requirements
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 approach reduces brush wear, noise, and electromagnetic interference, enabling the use of cost-effective electric motors with mechanical commutators in applications previously requiring brushless motors.
Implementation Method 1
the supply voltage signal is modulated to reduce its size at the commutation times by means of a modulation signal which is in phase with the commutation times
Data Source
Figure 1
Figure 2a~2e
Figure 3a~3b
AI summary
The invention relates to a method for controlling an electric motor (10) having a mechanical commutator (12), wherein in the method the points in time at which a commutation occurs are determined by means of a sensor (36) or without a sensor. Furthermore, the electric motor (10) is controlled by means of a supply voltage signal (16) comprising a sequence of pulses. Finally, the supply voltage signal (16) is modulated by means of a modulation signal (28) in order to reduce the size thereof at the commutation times (24).