Motor Drive Controller With Hardware Safe Torque Off
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Solution Overview
Problem
Existing motor drive controllers rely on software-programmed microprocessors for safety functionality, which can be complex and costly, and may not provide immediate and reliable fault detection and response, especially in critical applications where quick disabling of motor power is necessary.
Innovation Solution
A hardware-based motor drive controller system that includes a watchdog timer and gate buffers to independently disable motor rotation in response to fault detection, without relying on processor software control, using STO signals to ensure safe torque off and fault tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a software-programmed microprocessor is used for safety functionality, then the controller can detect conditions and disable the motor field, but the system complexity and certification cost increase
Solution Approach 1:
The patent replaces the software-programmed microprocessor system with a hardware-based logic circuit system. The control logic is implemented directly in hardware using logic gates, multiplexers, and state machines, eliminating the need for software diagnostics and microprocessor-based control. This hardware implementation provides deterministic response times and eliminates software certification requirements while maintaining safety functionality.
Solution Approach 2:
The patent divides the safety control function into separate hardware modules including fault detection circuits, watchdog timers, and independent control logic paths. Each module operates independently with dedicated hardware resources, allowing parallel processing of multiple safety conditions and reducing overall system complexity through functional decomposition.
2Reliability
If a software-programmed microprocessor is used for fault detection, then conditions can be monitored, but the response time is delayed compared to hardware-based solutions
Solution Approach 1:
The patent replaces software-based fault detection with hardware-based logic circuits that continuously monitor motor parameters. The control logic is implemented in combinatorial and sequential hardware circuits that provide deterministic, real-time response to fault conditions without the processing delays inherent in software execution.
Solution Approach 2:
The patent implements watchdog timers and preset trip circuits that are pre-configured to immediately activate safety functions when specific fault conditions are detected. The hardware circuits are designed with predetermined response paths that eliminate the need for software processing, ensuring the fastest possible response time for critical safety events.
3Reliability
If external motor-control safety components like mains contactors are installed, then safety functionality is provided, but the installation is time-consuming and expensive
Solution Approach 1:
The patent integrates motor control and safety functions into a single unified controller unit. The safety logic is combined with the motor drive control circuitry, eliminating the need for separate external safety components such as mains contactors, motor contactors, and external safety relays. This integration reduces installation complexity, component count, and system cost while maintaining full safety functionality.
Solution Approach 2:
The patent designs a multi-functional controller that performs both motor control and safety monitoring functions within the same hardware platform. The controller provides integrated protection against multiple fault types including overcurrent, overtemperature, and mechanical failures, replacing the need for multiple specialized external safety devices with a single universal safety controller.
Data Source
AI summary
A motor system with an input for coupling to a motor control signal that, when presented in a predetermined state, indicates a motor receiving power should be disabled from rotating. The system also includes controller circuitry for providing a disabling signal to motor rotation, independent of processor software control signaling and the power, in response to the control signal.