Temperature control system with external relay set
The problem of contact adhesion of EC fan relays is solved through external relay sets and three-level emergency response strategies, which improves contact reliability and system safety, reduces maintenance costs, and is suitable for temperature control of refrigeration equipment.
Patent Information
- Application Number
- CN202510641453.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-19
- Publication Date
- 2025-08-26
AI Technical Summary
When EC fans are used in the refrigeration industry, the relay contacts are prone to arcing when the high current is broken, causing adhesion, resulting in overheating and even fire, and it is difficult to maintain traditional PCB integrated relays.
The external relay group is adopted, including a control module, an external relay group, a power conversion module and a protection circuit, combined with the contact adhesion detection module and an emergency response module, and the contact adhesion problem is solved through a three-level response strategy, and electrical isolation is achieved through optocoupler devices.
It improves contact reliability and system safety, reduces maintenance costs, improves thermal management efficiency and system scalability, and realizes the convenience and safety of multi-relay control.
Smart Images
Figure CN120540422A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of refrigeration equipment circuit protection, in particular to a temperature control system with an external relay group. Background Art
[0002] The EC motor is a brushless DC maintenance-free motor with a built-in intelligent control module. It comes with an RS485 output interface, a 0-10V sensor output interface, a 4-20mA speed control switch output interface, an alarm device output interface, and a master-slave signal output interface.
[0003] EC fans are widely used in various fields due to their high efficiency, energy saving, and environmental friendliness. In the refrigeration industry, they are primarily used in cooling equipment to improve heat exchange efficiency. However, EC fans also place significant thermal stress on thermostats. When relay contacts interrupt high currents, arcing occurs, causing metal materials to melt and bond, preventing the contacts from separating properly. This bonding can cause equipment to remain energized, leading to overheating and even fires. Summary of the Invention
[0004] In order to overcome the above problems existing in the prior art, the present invention proposes a temperature control system with an external relay group.
[0005] The technical solution adopted by the present invention to solve its technical problems is: a temperature control system with an external relay group, including a control module, an external relay group, a power conversion module, and a load device. The control module is used to output start and stop instructions for the load device and receive relay status feedback signals; the external relay group is used to receive control signals from the control module, drive a high-capacity relay to control the on and off of the load device, detect contact status in real time, and perform emergency response to contact sticking, with a built-in contact sticking emergency algorithm; the power conversion module is used to supply power to the temperature control system; The external relay group includes a drive circuit, a relay array, and a protection circuit. The protection circuit is arranged at the contact end of the relay array and is used to suppress voltage spikes during the switching process.
[0006] The above-mentioned temperature control system with an external relay group, the contact sticking emergency algorithm includes a contact sticking detection module and an emergency response module. The contact sticking detection module is based on the differential voltage, and compares the voltage difference between the relay input end and the load end in real time. If the difference exceeds the threshold, it is determined that the contact is stuck and the emergency response module is triggered.
[0007] The above-mentioned temperature control system with an external relay group, the emergency response module adopts a three-level response strategy, the first level response is to apply a reverse current pulse; the second level response is to enable the backup relay channel through parallel connection of dual relays; the third level response is to trigger the solid-state relay to cut off the main circuit and alarm.
[0008] In the aforementioned temperature control system with an external relay group, the three-level response strategy is specifically as follows: when the contact voltage difference is less than 20% of the rated voltage difference, the first level response is triggered, and a reverse current pulse is applied to use electromagnetic force and mechanical vibration to remove slight adhesion; When the first-level response fails to be triggered three times, the second-level response is triggered, cutting off the power supply of the fault relay and activating the backup relay channel; If contact sticking is still detected after the second-level response is triggered, the third-level response is triggered, triggering the solid-state relay to cut off the main circuit, and storing the current / voltage waveform 60 seconds before the fault and reporting the ambient temperature.
[0009] The above-mentioned temperature control system with an external relay group, the working process of the contact sticking detection module is as follows: setting the threshold V1, configuring the sampling frequency, collecting the input and output voltages, calculating the difference voltage V2, if V2>V1, the fault count is increased by 1, when the fault count is greater than or equal to n times, it is determined that the contact is stuck; if V2≤V1, the fault count is reset, and the difference voltage is recalculated according to the sampling frequency.
[0010] In the above-mentioned temperature control system with an external relay group, the external relay module and the control module are electrically isolated by an optocoupler device, and the control signal drives the power amplifier circuit after photoelectric conversion to excite the electromagnetic relay.
[0011] The beneficial effects of the present invention are that, by adding an external relay module and a supporting detection mechanism to the temperature control module, the present invention can simultaneously control multiple relays and perform control on the same controller, which is more convenient and safer than traditional PCB integrated relay solutions, and significantly improves contact reliability, thermal management efficiency, maintenance convenience, and system scalability. The specific beneficial effects are as follows: (1) Improve contact reliability by using external high-capacity relays (30A contacts) to replace traditional PCB relays (usually ≤16A). The contact material is upgraded to silver tin oxide, and combined with RC buffer circuit and varistor protection, the contact on-off life is increased by 5 times.
[0012] (2) Reduced PCB temperature rise. The relay module uses independent heat dissipation and optocoupler isolation technology to block the heat generated by large current from being transferred to the main control PCB.
[0013] (3) Reduced maintenance costs. The relay module uses plug-in terminal connections. In the event of a fault, only the module needs to be replaced without disassembling the main control PCB, which shortens maintenance time and reduces spare parts costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 It is a schematic diagram of the temperature control system of the present invention; Figure 2 This is a working diagram of the contact adhesion detection module of the present invention; Figure 3 This is a workflow diagram of the emergency response module of the present invention. DETAILED DESCRIPTION
[0015] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.
[0016] like Figure 1 As shown, this embodiment discloses a temperature control system with an external relay group. By physically separating the high-current relay module from the main control PCB, combined with redundant contact design and thermally isolated transmission, it effectively solves the problems of contact adhesion, heat conduction damage, and difficult maintenance in traditional solutions. The system includes a control module, an external relay group, a power conversion module, and a load device. The control module is used to output start and stop commands for the load device and receive relay status feedback signals. The external relay group is used to receive control signals from the control module, drive high-capacity relays to control the on and off of the load device, detect contact status in real time, and provide emergency response to contact adhesion. It also has a built-in contact adhesion emergency algorithm. The power conversion module is used to power the temperature control system.
[0017] Relays are automatic switching elements with isolation functions. They are widely used in remote control, telemetry, communication, automatic control, mechatronics and power electronic equipment, and are one of the most important control elements.
[0018] A relay module consists of a sensing mechanism (the input portion) that can detect certain input variables (such as current, voltage, power, impedance, frequency, temperature, pressure, speed, and light). The output portion is an actuator that controls the "on" and "off" state of the controlled circuit. Between the relay input and output, there is an intermediate mechanism (the driver portion) that couples and isolates the input, processes the function, and drives the output. An external relay module primarily consists of a driver circuit, relay array, protection circuit, and a contact sticking emergency response algorithm.
[0019] The external relay module is a high-reliability load control device based on an electromechanical separation architecture. Through physical isolation and redundant design, it solves the contact sticking problem that exists in traditional PCB integrated relays when driving high-current loads.
[0020] Structurally, the module is electrically isolated from the main control PCB via an optocoupler. The control signal undergoes photoelectric conversion, driving the power amplifier circuit, ultimately energizing the high-capacity electromagnetic relay. A protective circuit is configured at the relay contact end: an RC snubber network, a varistor, and a freewheeling diode, effectively suppressing voltage spikes during the switching process.
[0021] The built-in contact sticking emergency algorithm monitors the relay contact status in real time and triggers the protection mechanism when a contact failure occurs. This patent provides a contact sticking emergency algorithm, which is divided into two parts: contact sticking detection part and emergency response part.
[0022] The contact sticking detection part is based on differential voltage comparison. The contact status detection part compares the voltage difference between the relay input terminal (control signal) and the load terminal (actual voltage) in real time. If the voltage difference exceeds the set threshold, it is immediately determined to be contact sticking and the emergency response strategy is triggered, such as Figure 2 As shown in the figure, the specific working process is as follows: set the threshold V1, configure the sampling frequency, collect the input and output voltages, calculate the difference voltage V2, and if V2>V1, increase the fault count by 1. When the fault count is greater than or equal to n times, the contact is determined to be stuck. If V2≤V1, reset the fault count and recalculate the difference voltage based on the sampling frequency.
[0023] The emergency response adopts a three-level response strategy: The first-level response is to apply a reverse current pulse (5-10A, 10ms) to use electromagnetic force and mechanical vibration to remove slight adhesions.
[0024] The second level response is to connect two relays in parallel and enable redundant relay channels.
[0025] Finally, the solid-state relay is triggered to cut off the main circuit and an alarm is given through the buzzer / LED.
[0026] Three-level response strategy workflow: When the contact voltage difference is less than 20% of the rated voltage difference, the first level response is triggered, and a reverse current pulse (5-10A, 10ms) is applied to use electromagnetic force and mechanical vibration to remove slight adhesion.
[0027] When the first-level response fails to be triggered three times, the second-level response is triggered, cutting off the power supply to the fault relay and activating the backup relay channel.
[0028] If contact sticking is still detected after the second level response is triggered, the third level response is triggered, triggering the solid-state relay to cut off the main circuit, and storing the current / voltage waveform 60 seconds before the fault, and reporting the ambient temperature. The complete process is as follows Figure 3 shown.
[0029] The overall working process of this embodiment includes: after 220V power is input into the temperature control system of this embodiment, 12V DC power is output through the power conversion module to power the lamp and the control module respectively. The power supply of the external relay module is realized through the 12V output terminal of the control module.
[0030] When high temperature causes the contacts to stick and the compressor and fan cannot be shut down, the control module detects the shutdown command and actively cuts off the 12V power supply of the external relay module and forcibly disconnects the power supply to the compressor / fan.
[0031] This embodiment achieves high reliability and easy maintainability for commercial display cabinet thermostats by adding an external relay module, thereby improving the safety of commercial display cabinets. The closed-loop control process, from temperature detection to fault protection, significantly reduces energy loss and repair costs caused by contact sticking, making it particularly suitable for high-frequency use scenarios such as supermarkets and cold chain logistics.
[0032] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the spirit and scope of protection of the present invention, and such modifications or equivalent substitutions shall also be deemed to fall within the scope of protection of the present invention.
Claims
1. A temperature control system with an external relay group, characterized in that: It includes a control module, an external relay group, a power conversion module, and a load device. The control module is used to output start and stop instructions for the load device and receive relay status feedback signals. The external relay group is used to receive control signals from the control module, drive high-capacity relays to control the on and off of the load device, detect contact status in real time, and perform emergency responses for contact adhesion. It has a built-in contact adhesion emergency algorithm. The power conversion module is used to power the temperature control system. The external relay group includes a drive circuit, a relay array, and a protection circuit. The protection circuit is arranged at the contact end of the relay array and is used to suppress voltage spikes during the switching process.
2. A temperature control system with an external relay group according to claim 1, characterized in that: The contact sticking emergency algorithm includes a contact sticking detection module and an emergency response module. The contact sticking detection module is based on the differential voltage and compares the voltage difference between the relay input terminal and the load terminal in real time. If the difference exceeds the threshold, it determines that the contact is stuck and triggers the emergency response module.
3. A temperature control system with an external relay group according to claim 2, characterized in that: The emergency response module adopts a three-level response strategy. The first-level response is to apply a reverse current pulse; the second-level response is to enable the backup relay channel through parallel connection of dual relays; and the third-level response is to trigger the solid-state relay to cut off the main circuit and alarm.
4. A temperature control system with an external relay group according to claim 3, characterized in that: The three-level response strategy is specifically as follows: when the contact voltage difference is less than 20% of the rated voltage difference, the first level response is triggered, and a reverse current pulse is applied to use electromagnetic force and mechanical vibration to remove slight adhesion; When the first-level response fails to be triggered three times, the second-level response is triggered, cutting off the power supply of the fault relay and activating the backup relay channel; If contact sticking is still detected after the second-level response is triggered, the third-level response is triggered, triggering the solid-state relay to cut off the main circuit, and storing the current / voltage waveform 60 seconds before the fault and reporting the ambient temperature.
5. The temperature control system with an external relay group according to claim 2, characterized in that: The working process of the contact sticking detection module is as follows: set the threshold V1, configure the sampling frequency, collect the voltages of the input and output terminals, calculate the difference voltage V2, and if V2>V1, increase the fault count by 1. When the fault count is greater than or equal to n times, the contact is determined to be stuck; If V2≤V1, the fault count is reset and the difference voltage is recalculated according to the sampling frequency.
6. The temperature control system with an external relay group according to claim 1, characterized in that: The external relay module and the control module are electrically isolated by an optocoupler device, and the control signal drives the power amplifier circuit after photoelectric conversion to excite the electromagnetic relay.