Heater SSR Time-Proportional Output for Accurate ON/OFF Timing
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Solution Overview
Problem
Conventional output control systems in factory automation face deviations in time proportional output (TPO) due to the cycle time of the controller, leading to mismatches between set and actual ON/OFF times for output apparatuses, especially when the control cycle and communication cycle are not synchronized.
Innovation Solution
An output control unit that acquires an operation amount from a control apparatus and performs time proportional output to a switching apparatus, such as an SSR, to accurately control the driving and stopping of output devices like heaters, ensuring that the actual output values match the intended settings by adjusting the ON/OFF times based on the acquired operation amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the controller uses a fixed cycle time for control operations, then the controller operation is simplified and stable, but the time proportional output (TPO) deviates from the intended setting due to mismatch between controller cycle time and TPO control cycle
Solution Approach 1:
The patent introduces an output control unit as an intermediary device between the controller and the output apparatus. This unit receives the operation amount from the controller and independently performs the time proportional output control, generating ON/OFF instructions that accurately reflect the intended TPO ratio. The intermediary absorbs the cycle time mismatch problem, allowing the controller to operate with fixed cycle time while the output control unit ensures precise TPO execution by calculating appropriate ON/OFF durations based on the received operation amount and its own control cycle.
2Device complexity
If the controller directly controls the output apparatus with fixed cycle time, then the control system structure is simple, but the actual ON/OFF times do not match the intended settings due to cycle time mismatch
Solution Approach 1:
The output control unit serves as a mediator that receives simple operation amounts from the controller and transforms them into precise ON/OFF control signals. This intermediary layer adds minimal structural complexity while solving the fundamental problem of cycle time mismatch, enabling accurate TPO control without requiring the controller to change its fixed cycle time operation mode.
Solution Approach 2:
The output control unit dynamically adjusts the ON/OFF timing based on the received operation amount and its own control cycle, rather than relying on fixed controller cycle time. This dynamic adjustment mechanism allows the system to maintain simple controller structure while achieving accurate time proportional output through adaptive timing calculation in the output control unit.
3Productivity
If the controller adjusts output values in discrete steps based on its cycle time, then the control processing is straightforward, but fine-grained control of the output apparatus cannot be achieved
Solution Approach 1:
The patent segments the control function into two parts: the controller handles high-level operation amount determination with efficient discrete processing, while the output control unit handles the detailed time proportional output calculation with finer resolution. This segmentation allows the controller to maintain efficient processing while the output control unit provides the necessary fine-grained control by calculating precise ON/OFF durations based on the operation amount and its control cycle parameters.
Solution Approach 2:
The output control unit dynamically calculates the ON/OFF timing with fine resolution based on the received operation amount, enabling precise control that is not limited by the controller's discrete step size. This dynamic calculation provides the fine-grained control resolution needed for accurate TPO while the controller maintains its efficient discrete processing approach.
Data Source
AI summary
A temperature control unit according to one or more embodiments may include an acquisition unit that is configured to acquire an operation amount from a controller, and an SSR control unit that is configured to perform time proportional output of an instruction to drive or stop a heater to SSR after reflecting the operation amount.