Brushless Motor Control Device Using RC Filter for Circuit Diagnostics
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Solution Overview
Problem
Conventional brushless motor control devices cannot effectively diagnose and prevent errors in rotational speed and torque due to abnormal conditions in current detection and AD converter circuits, leading to variations in airflow and noise in cooling fans, requiring larger motors and complex diagnostic circuits, which increase costs.
Innovation Solution
A brushless motor control device with an RC filter and diagnostic processing method that determines the abnormality of AD converter circuits, clock generation circuits, and current detection circuits by analyzing digital signals from these components, allowing for error prevention and control without the need for additional complex diagnostic circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional diagnostic methods are used to determine clock generation circuit abnormality, then clock generation circuit abnormality can be detected, but current detection circuit and AD converter circuit abnormality cannot be detected, resulting in increased errors in rotational speed and torque
Solution Approach 1:
The patent applies universality by making the AD converter circuit serve multiple functions: it converts current detection circuit output signals to digital signals for normal motor control operations, and simultaneously converts test voltages applied to specific pins to digital signals for diagnostic purposes. This allows the same hardware circuit to perform both operational and diagnostic functions without adding separate dedicated diagnostic hardware, thereby detecting abnormalities in current detection circuits and the AD converter circuit itself while avoiding increased device complexity
Solution Approach 2:
The patent implements self-service by enabling the AD converter circuit to diagnose itself and the current detection circuit. By applying test voltages to specific pins and using the AD converter circuit's own digital conversion capability to read the converted values, the system can autonomously determine whether the current detection circuit or AD converter circuit is abnormal without requiring external diagnostic equipment or complex additional circuits
2Reliability
If complex diagnostic circuits are added to detect abnormalities in current detection and AD converter circuits, then detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies universality by making the AD converter circuit serve multiple functions: it converts current detection circuit output signals to digital signals for normal motor control operations, and simultaneously converts test voltages applied to specific pins to digital signals for diagnostic purposes. This allows the same hardware circuit to perform both operational and diagnostic functions without adding separate dedicated diagnostic hardware, thereby detecting abnormalities in current detection circuits and the AD converter circuit itself while avoiding increased device complexity
Solution Approach 2:
The patent implements self-service by enabling the AD converter circuit to diagnose itself and the current detection circuit. By applying test voltages to specific pins and using the AD converter circuit's own digital conversion capability to read the converted values, the system can autonomously determine whether the current detection circuit or AD converter circuit is abnormal without requiring external diagnostic equipment or complex additional circuits
3Reliability
If a large motor is used to make allowance for increased variations in airflow and noise, then performance stability is improved, but device size and cost increase
Solution Approach 1:
The patent applies preliminary action by performing diagnostic checks before motor control operations to detect abnormalities in the current detection circuit and AD converter circuit. By identifying and addressing potential issues before they cause performance degradation, the system prevents increased variations in rotational speed and torque that would otherwise require a larger motor to compensate for, thereby maintaining performance stability with a smaller motor size
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 prevents increased errors in rotational speed and torque, reducing airflow and noise variations in cooling fans, enabling smaller motor designs and lower costs by using a small microcomputer for diagnostics.
Implementation Method 1
an RC filter 26 into which a pulse signal PLS generated based on a clock pulse CLK is input
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The brushless motor control device according to the present invention includes a drive controller, current detection circuits, AD converter circuits, a clock generation circuit, a pulse output circuit, and an RC filter. The drive controller generates a driving signal for driving a brushless motor. The current detection circuits each detect a current of the brushless motor. The AD converter circuits are each connected to a different one of the current detection circuits. The clock generation circuit outputs a clock pulse. The pulse output circuit outputs a pulse signal according to the clock pulse. The RC filter receives the pulse signal. The RC filter is formed of a resistor and a capacitor connected in series. A pull-up resistor connecting to a predetermined power supply is connected to an intermediate connection point between the resistor and the capacitor. The intermediate connection point is connected to the AD converter circuits. Based on output values form the AD converter circuits, it is determined whether the clock generation circuit, the AD converter circuits, and the current detection circuit are in an abnormal condition.