Progressive Motor Driver Braking for Fan Overcurrent Control
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Solution Overview
Problem
Conventional motor drivers fail to effectively brake fan motors when a fan is replaced, leading to either insufficient braking or excessive current flow, potentially damaging the motor due to overheating or overcurrent.
Innovation Solution
A motor driver with a progressive driving mechanism that uses a progressive driving setting circuit, waveform constructing circuit, and motor driving circuit to control the braking current based on air intensity, applying varying braking forces to prevent motor damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high-side switches are switched on for a long period to increase braking force, then the motor rotational speed can be reduced to zero, but excessive braking currents flow through the motor causing damage due to overcurrent
Solution Approach 1:
The patent applies dynamics by making the braking force adjustable rather than fixed. The control circuit dynamically adjusts the duty cycle of the square wave signal applied to the high-side switches, enabling the braking force to be optimized according to real-time motor operating conditions such as rotational speed and load, thus achieving effective braking without excessive current that would damage the motor.
Solution Approach 2:
The patent changes the parameter of braking current by controlling the duty cycle of the square wave signal. By varying the duty cycle parameter, the control circuit regulates the average current flowing through the motor during braking, preventing both insufficient braking (when duty cycle is too low) and overcurrent damage (when duty cycle is too high), thus resolving the technical contradiction.
2Object-affected harmful factors
If high-side switches are switched on for a short period to limit braking current, then motor damage due to overcurrent is prevented, but the rotational speed of the motor cannot be reduced to zero
Solution Approach 1:
The control circuit dynamically adjusts the duty cycle based on real-time motor conditions. During the braking process, the duty cycle can be progressively modified to first limit current protection and then achieve complete stopping, making the system adaptive rather than static.
Solution Approach 2:
The patent uses periodic square wave signals with adjustable duty cycles to control the high-side switches. By periodically switching the switches with optimized duty cycles, the system achieves both current limitation and effective braking through rhythmic application of braking force.
3Device complexity
If conventional motor drivers are used for braking, then the control mechanism is simple, but the braking effectiveness is insufficient and may cause motor damage
Solution Approach 1:
The control circuit incorporates feedback mechanisms that monitor motor conditions during braking and adjust the duty cycle accordingly. This feedback enables the system to automatically optimize braking effectiveness while preventing overcurrent damage, significantly improving reliability without requiring complex external control systems.
Solution Approach 2:
The motor driver circuit performs self-regulation during braking by using its own control circuit to monitor and adjust the braking current. The system serves itself by automatically optimizing braking parameters based on real-time conditions, eliminating the need for complex external control while ensuring reliable braking.
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 progressive driving mechanism effectively controls the braking current to prevent motor damage by adjusting the braking force according to air intensity, ensuring safe and efficient motor operation.
Implementation Method 1
a motor driver circuit (30) connected to the progressive waveform constructing circuit (20) and the motor (MT). The motor driver circuit (30) is configured to output a progressive driving signal to the motor (MT) according to the progressive waveform signal (DTS)
Implementation Method 2
the motors have small back electromotive force. At this time, if the high-side switches of the conventional motor drivers are in the on-state for a long period of time, the excessive braking currents flow through the motors
Data Source
AI summary
A motor driver having a progressive driving mechanism is provided. The motor driver includes a progressive driving setting circuit, a progressive waveform constructing circuit and a motor driving circuit. The progressive driving setting circuit outputs a progressive driving setting signal that is progressively changed over time. The progressive driving setting signal has a plurality of progressive driving set voltages respectively at a plurality of set time points. The progressive driving set voltages are different from each other. The progressive waveform constructing circuit sets a plurality of waveforms of a progressive waveform signal according to the progressive driving set voltages. Duty cycles of the plurality of waveforms of the progressive waveform signal are different from each other. The motor driving circuit drives a motor according to the progressive waveform signal.