Motor Controller Safety Integration via Cut-off Circuit
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Solution Overview
Problem
Existing motor controllers lack flexibility in designing safety systems, as they typically require separate blocks for safety processing and motor control, limiting design options to either network-based or wired safety inputs.
Innovation Solution
A motor controller with a communication circuit for network signal transmission and reception, a safety control unit that processes safety data, a cut-off circuit to halt motor power based on safety signals, and a self-diagnosis unit for abnormality detection, allowing safe motor operation through both network and wired safety inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate functional blocks are used for safety processing and motor control, then safety function is achieved, but design flexibility is reduced
Solution Approach 1:
The patent combines the safety control unit with the motor control unit into a single integrated motor controller. The safety control unit receives safety input signals and processes safety communication data, then outputs a drive permission signal that is logically ANDed with the motor drive command value. This integration maintains safety functionality while enabling flexible design configurations where the same controller can operate with either network-based safety communication or wired safety input signals, thus resolving the contradiction between reliability and design flexibility.
2Length of stationary object
If network-based safety communication is used, then signal transmission distance is extended, but communication delay may increase
Solution Approach 1:
The patent introduces a dedicated safety communication unit as an intermediary that processes safety data according to a predetermined protocol. This unit extracts safety signals from network communication data and transmits them to the safety control unit. By using this intermediary processing mechanism, the system can maintain extended transmission distance through network communication while managing communication delay through protocol-based processing, thus resolving the contradiction between transmission distance and communication delay.
3Reliability
If redundant safety input signals are received, then safety reliability is improved, but system complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the safety control unit receives redundant safety input signals through the safety input unit, processes them along with safety communication data, and generates a drive permission signal. The logical AND operation between the drive permission signal and the motor drive command value creates a feedback control mechanism that ensures safety while managing complexity through systematic signal processing rather than separate redundant safety systems.
Data Source
AI summary
A safety system has higher user design flexibility. Motor controllers (20, 30) include a motor drive circuit (207) that outputs a motor voltage command signal for driving motors (90, 100) in accordance with a motor drive command value, an inverter (211) that supplies power for driving the motors (90, 100) by switching based on the motor voltage command signal, a safety control unit that outputs a drive permission signal for driving the motors (90, 100) in accordance with communication data received through a communication circuit (213), a cut-off circuit (209) that receives the drive permission signal and the voltage drive command signal and cuts off the voltage drive command signal to an inverter (211) when receiving no drive permission signal, and a safety input unit (205) that receives redundant safety input signals. The cut-off circuit (207) receives a logical AND of the safety input signal and the drive permission signal.