Motor Drive Control Device Abnormality Detection Circuit
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Solution Overview
Problem
Existing motor drive control devices fail to safely shut down AC motors when abnormalities occur in the PWM signal generator or if abnormalities are present in the drive control or monitor control circuits, and they cannot conduct preliminary checks on the transmission of drive command signals to switching elements in a three-phase full-wave semiconductor bridge circuit.
Innovation Solution
A motor drive control device with a semiconductor bridge circuit and a monitor control circuit that generates mutually-monitoring signals to detect operational abnormalities, using drive command signal interruption circuits to immediately stop the AC motor by inhibiting drive command signals if any abnormality is detected, and conducting preliminary checks on the switching elements' operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a safety stop circuit with three-state buffers is used to interrupt PWM signals, then the motor can be stopped in abnormal conditions, but the device cannot detect abnormalities in the PWM signal generator or drive control circuits themselves
Solution Approach 1:
The patent implements a monitor control circuit that continuously monitors the drive control circuit's operation and generates monitoring signals. This feedback mechanism allows the system to detect abnormalities in the drive control circuit itself, not just respond to them. The monitor control circuit receives monitoring signals from the drive control circuit and can independently generate inhibition commands to stop the motor if abnormalities are detected, resolving the contradiction by adding reliability through feedback without excessive complexity.
Solution Approach 2:
The patent introduces a drive command signal interruption circuit as an intermediary component between the drive control circuit and the PWM signal generator. This intermediary circuit receives inhibition commands from either the drive control circuit or the monitor control circuit and interrupts the drive command signals to the PWM signal generator. By placing this intermediary layer, the system gains the ability to stop the motor even when the drive control circuit itself is abnormal, improving reliability while maintaining manageable complexity through modular design.
2Speed
If the drive control circuit directly controls PWM signal generation, then the control response is fast, but preliminary checks on drive command signal transmission cannot be conducted
Solution Approach 1:
The patent implements a preliminary check function that operates before the motor starts normal operation. The drive control circuit generates a check command signal that triggers the PWM signal generator to output a specific check signal through the drive command signal interruption circuit. This preliminary action allows the system to verify that the drive command signal transmission path is functioning correctly before actual motor control begins, ensuring reliability without affecting the speed of normal control operations.
3Reliability
If multiple inhibition command signals are introduced to interrupt drive command signals, then motor shutdown reliability is improved, but the device complexity increases
Solution Approach 1:
The patent combines the inhibition command generation and signal interruption functions into a single integrated drive command signal interruption circuit. This circuit receives inhibition commands from either the drive control circuit or the monitor control circuit and handles the interruption of drive command signals to the PWM signal generator. By merging these functions, the system achieves high shutdown reliability through multiple inhibition pathways while avoiding the complexity of completely separate circuits, as the interruption logic is consolidated in one place.
Data Source
AI summary
A motor drive control device is provided in which if any abnormality occurs in a drive control circuit, drive command signals the drive control circuit generates are interrupted at once, so that an AC motor can be stopped in safety. A monitor control circuit and drive command signal interruption circuit are provided to the drive control circuit that takes variable-speed control of the AC motor supplied with power from a DC drive power source via a semiconductor bridge circuit. If any abnormality occurs in the drive control circuit, the drive command signals the drive control circuit generates are interrupted at once. When starting operation, the drive control circuit and monitor control circuit cooperate with each other to conduct preliminary check as to whether or not the drive command signal interruption circuit operates normally, base on a predetermined time schedule, and stop the AC motor without fail if any abnormality occurs during operation.