Double-path power supply and hot backup control method and system for LED display screen heat plate

Abstract

The present application relates to the technical field of power supply redundancy and operation control of electric heating equipment and stage performance equipment, and particularly relates to a double-path power supply and heat backup control method and system for a heating plate of an LED display screen, aiming at power supply fluctuation in a performance site, temperature sensor failure and the need for continuous and stable heat supply under a maintenance window, the present application takes a heating plate with double-path power supply and heat backup, double-zone independent temperature control and double-signal monitoring hardware architecture as a hardware execution carrier, and constructs a control scheme of double-path independent power supply and heat backup switching, double-zone independent heating and temperature cross verification, partitioned temperature control compensation, switching power reduction and control card live maintenance. The system is switched off first and then on by a solid-state relay array, and the dead zone voltage is maintained by an energy storage capacitor. Double-path temperature signals cross verify to identify hardware failure and operate in degraded mode. Partitioned temperature control compensation edges radiate heat. A redundant interface unit supports zero-crossing live heat insertion and removal of the control card.

Description

Technical Field

[0001] This invention relates to the field of power supply redundancy and operation control technology for electric heating equipment and stage performance equipment, specifically to a dual-path independent power supply thermal backup switching control method for a large-size heating plate for LED displays, and a control system for implementing this method. Background Technology

[0002] Carbon fiber heating elements are widely used in heating panels for underfloor heating, wall heating, and stage performance equipment due to their high electrothermal conversion efficiency, comfortable far-infrared radiation, and uniform surface heating. As stage performances place stringent requirements on the continuous operation of heating panels, there must be no visible interruption or flickering of heating during the performance, otherwise it will directly affect the stage visual effect; moreover, the tight schedule of touring performances means that the equipment maintenance window is usually only a very short time between performances.

[0003] The aforementioned heating panel plays a more specific supporting role in LED display equipment. An LED display screen consists of an array of LED chips and a power supply that powers them. The chips and power supply are subject to two constraints regarding operating temperature: firstly, the failure rate of the power supply and chips increases in low-temperature environments, making initial startup in outdoor settings during winter prone to abnormalities; secondly, in high-humidity environments or after rain, condensation easily forms on the back of the internal modules of the screen, and the condensation adhering to the printed circuit board and device pins poses a risk of leakage and short circuits. Furthermore, the combined effect of the large-size screen's own heat generation and heat dissipation to the environment after lighting can lead to visible differences in brightness and color temperature if the internal temperature distribution is uneven or fluctuates significantly with operating conditions due to inconsistent chip decay. Therefore, LED displays require a supporting heating panel that can provide continuous heating over a long period, maintain uniform surface temperature, be adjustable according to operating conditions, and continue heating even in the event of power failure.

[0004] Patent document CN209263121U discloses a dual-power switching carbon fiber heating system, including a carbon fiber heating wire, a photovoltaic power source, an AC power source, and a first and second electronic digital switch controlled by a light sensor. This system uses the photovoltaic power source to power the carbon fiber heating wire when there is sufficient sunlight, and switches to AC power when sunlight is insufficient to achieve energy saving. The switching devices can be MOSFETs, thyristors, thin-film electronic switches, contactors, or optocouplers. This document and similar solutions focus on energy saving in power supply, using light intensity as the switching criterion, and do not address the unstable power supply conditions and long-term unattended operation conditions at performance venues.

[0005] Several objective technical constraints exist in the practical engineering application of carbon fiber heating panels. Large-size planar heating elements inherently exhibit a higher heat dissipation rate at the edges than at the center. Without targeted heat equalization treatment, the overall temperature distribution cannot meet the uniformity requirements of performance lighting. The power quality at performance venues varies, with voltage drops and even short-term outages being common. Since heating panels are safety-related equipment visible to the audience, any heating interruption will be immediately noticeable. Heating panels operate continuously in the high-voltage and electromagnetic interference environment of the stage, posing a risk of hardware failure such as open circuits and short circuits to analog components like temperature sensors. These failures often manifest as temperature control deviations rather than immediate shutdowns, making them difficult for operators to detect immediately. Furthermore, maintenance of touring equipment is limited by brief performance breaks; overall power outages for maintenance would reduce available time and increase the risk of downtime. All these constraints point to the same engineering goal: improving the continuous operational reliability of large-size heating panels under complex on-site conditions.

[0006] Therefore, there is a need in this field for a large-size heating plate solution that can adapt to power fluctuations at the performance site, has self-diagnostic capabilities, and is easy to maintain intermittently. Summary of the Invention

[0007] This invention aims to solve the problem of continuous operational reliability of large-size heating panels under complex conditions at performance venues. It ensures that the heating panels can maintain stable heating, operate safely, and facilitate maintenance even under constraints such as power supply fluctuations, sensor failures, and short maintenance windows. Furthermore, when used as a component of LED displays, it addresses issues such as startup reliability in low-temperature environments, suppression of condensation within the screen in high-humidity environments, and the impact of surface temperature uniformity on display consistency. This problem is solved through a dual-power supply thermal backup control method for heating panels used in LED displays, and a control system that implements this method.

[0008] To address its technical problems, this invention provides a dual-power supply thermal backup control method for heating panels used in LED displays. The method, implemented in a heating panel with a hardware architecture featuring dual-power supply thermal backup, independent temperature control in two zones, and dual-signal monitoring, includes the following steps: synchronously acquiring the temperature and power supply voltage of both zones; monitoring the power supply voltage and performing a first-off-then-on switching when the main power supply drops or is interrupted, maintaining the load voltage by an energy storage capacitor during the switching dead zone; acquiring the temperature of both zones and identifying hardware faults based on the temperature difference between the two zones and the open / short circuit criteria of a single-channel temperature sensor, providing graded protection, and maintaining degraded operation by cross-estimating the temperature of the other zone when a single-channel temperature sensor fails; independently controlling the temperature of both zones and compensating for edge heat dissipation by looking up the temperature difference between the two zones; synchronously reducing the duty cycle of both zones to a limited level during power supply switching; supporting hot-swapping of the control card via a redundant interface unit and reporting operating status and fault information externally.

[0009] In the above method, the synchronous acquisition step synchronously acquires the dual-zone temperature and power supply voltage via an analog-to-digital converter at a fixed period; the triggering condition for the first-to-disconnect and then-to-connect switching is that the power supply voltage drops below a set threshold or the power outage lasts for more than a set duration, the total switching time is not greater than the set upper limit, and the original solid-state relay in the conducting circuit is disconnected first, and the backup solid-state relay is closed after the dead zone.

[0010] The above method, wherein the step of protection by graded method includes: when the temperature difference between the two zones exceeds the alarm threshold, it enters the first level of power reduction; when the single-channel temperature sensor fails, it enters the second level of current limiting; when both channels fail or the temperature exceeds the safety limit, it enters the third level of hard cut-off; the confirmation of the single-channel temperature sensor failure requires multiple consecutive sampling cycles to meet the open circuit or short circuit criteria.

[0011] The above method, in the step of independently implementing temperature control for the dual zones, uses an independent temperature control instance to output a drive signal, and adds the edge heat dissipation compensation obtained from the lookup table to the set temperature side before sending it into the temperature control calculation, and enables integral separation anti-saturation and duty cycle clamping; in the step of reducing the duty cycle to a limited level during power supply switching, it is smoothly restored to the rated value by ramping after the main power is restored; in the hot-swap step, the AC side closes the corresponding power supply route at the voltage zero crossing point by zero-crossing detection, so that the heating surface does not stop heating due to DC bus interruption during the replacement of the control card.

[0012] To address its technical problems, this invention also provides a dual-power supply thermal backup control system for heating panels of LED displays, including a power supply thermal backup unit, a dual-zone heating unit, a temperature monitoring unit, a zone temperature control unit, a power reduction unit, and a redundant interface unit. The power supply thermal backup unit connects to two independent AC power supplies and, when the main power supply drops or is interrupted, switches the load to the backup power supply according to the principle of disconnecting first and then connecting, maintaining the load voltage with the help of an energy storage capacitor, ensuring that heating is not interrupted due to a single power supply anomaly. The dual-zone heating unit is divided into two electrically isolated independent circuits to isolate single-zone faults. The temperature monitoring unit collects the temperatures of both zones and cross-verifies and identifies hardware faults based on the temperature difference between the two zones and the open / short circuit criteria of a single sensor. In the event of a single-zone failure, it maintains degraded operation by estimating the temperature of the other zone. The zone temperature control unit independently controls the temperature of the two zones and compensates for edge heat dissipation to maintain uniform temperature across the entire surface. The power reduction unit synchronously reduces the duty cycle of both zones to a limited level during power supply switching to ensure basic operation of the backup power supply. The redundant interface unit supports hot-swapping of the control card while it is powered on and reports status and faults, thereby achieving uninterrupted maintenance.

[0013] In the aforementioned system, the power supply hot backup unit includes a solid-state relay array and an energy storage capacitor connected in parallel to the DC bus side. Two independent AC power supplies are introduced into each heating circuit of the dual-zone heating unit through the solid-state relay array, so that when the main power supply drops or is interrupted, the original solid-state relay in the conducting circuit is first disconnected, and the backup solid-state relay is closed after passing through the dead zone to complete the switching.

[0014] In the aforementioned system, the dual-zone heating unit is formed by physically dividing a carbon fiber preform into two electrically isolated independent heating circuits. An insulating isolation structure is provided between the two circuits to prevent the hidden short circuit caused by scratches or moisture in the single-zone heating layer from spreading to the adjacent zone.

[0015] The temperature monitoring unit of the above system includes a temperature sensor and a graded protection circuit respectively arranged in one of the two zones. The graded protection circuit is configured to handle faults in three levels: early warning power reduction, single zone current limiting, and hard cut-off. When a single temperature sensor fails, the temperature of the fault zone is estimated by cross-estimation of the temperature of the other zone to maintain degraded operation.

[0016] In the above system, the partitioned temperature control unit is an independent temperature control instance for each of the two zones. The compensation amount obtained by looking up the heat loss coefficient table of the dual-zone temperature difference is superimposed on the set temperature side and then sent into the temperature control calculation to suppress the temperature difference across the entire area.

[0017] In the aforementioned system, the power reduction unit is configured to reduce the dual-zone synchronous duty cycle to a limited duty cycle during power supply switching or maintenance mode, and then smoothly restore it to the rated duty cycle by ramping up after the main power supply stabilizes. The redundant interface unit includes a dual-port waterproof terminal block and an industrial bus interface. During maintenance, the control card is inserted or removed on the DC side via the dual-port waterproof terminal block, and the AC side is closed at the zero-crossing voltage point by zero-crossing detection, enabling uninterrupted maintenance of the heating surface. The operating status and fault information are reported via the industrial bus using a unified fault code.

[0018] In the aforementioned system, the redundant interface unit further includes a status indication unit, which includes at least three light-emitting indicator elements. The power supply terminals of the three light-emitting indicator elements are all connected to the DC bus side, and the three light-emitting indicator elements are respectively configured to indicate three operating states: normal operation, warning and degraded operation, and fault hard disconnection.

[0019] The beneficial effects of this invention are:

[0020] 1. Uninterrupted heating: Dual independent power supply and solid-state relay array switch between interruption and reconnection, with a total switching time of no more than 15ms. With the support of bus capacitor, the cabinet heating is uninterrupted and there is no visual flicker when a single mains power is interrupted.

[0021] 2. Fault self-diagnosis and isolation: Dual-channel NTC cross-validation and three-level graded protection. Single sensor failure can be shielded and degraded to lower operating level, while hard disconnection is only required when both sensors fail, significantly improving operational safety.

[0022] 3. Uniform heat dissipation across the entire area: Independent PID control for each zone and dynamic compensation for edge heat dissipation eliminate the temperature difference between the center and edge of large-size panels.

[0023] 4. Easy maintenance: The HUB board features dual-port waterproof terminal blocks with zero cross-connection hot-swappable design, supporting live replacement of control cards during performance breaks.

[0024] 5. Energy efficiency and lifespan: The power reduction strategy maintains no less than 60% of the rated power under backup power conditions, extending the UPS's endurance and protecting components.

[0025] 6. Matching display consistency: As a supporting component of the LED display screen, the heating plate suppresses temperature differences in different areas of the screen by providing uniform heating along the surface, and keeps the cavity inside the screen above the dew point temperature under high humidity conditions. Detailed Implementation

[0026] The implementation of the present invention will be further described below in conjunction with the technical solution.

[0027] The control method of this invention, implemented by the MCU firmware in a heating plate with dual-power supply thermal backup, dual-zone independent temperature control, and dual-signal monitoring hardware architecture, includes the following steps: Step S1 is triggered at 500ms cycles. At the arrival of each cycle, the synchronous conversion between the NTC voltage divider signal and the mains voltage in zones A and B is initiated sequentially. The conversion result is written to the dual-zone temperature buffer and voltage buffer to avoid sampling jitter caused by the main loop polling. The voltage monitoring in step S2 and the temperature cross-verification in step S3 are executed sequentially in the control flow. Both are based on the same sampling result, ensuring that switching and fault determination are based on data from the same time window, avoiding misjudgments caused by asynchronous sampling. After the system powers on, the MCU completes the initialization of all peripherals and enters the main loop with a 500ms cycle: Each cycle first samples the dual-channel NTC and mains voltage (step S1). If the mains voltage is below 180V, a first-off-then-on switching is initiated, and power is simultaneously reduced (steps S2 and S5 work together). Then, the dual-channel NTC is checked for normal operation (step S3). If abnormal, it is handled according to the three-level protection system. If normal, the partitioned PID calculation is executed, and the PWM is output to drive the heating element (step S4). Finally, the status code is reported via RS485 (step S6) and sampling is returned. If any of the three-level protection systems escalates to hard cutoff, the main loop exits and the alarm is locked until manual reset or the fault is cleared. The partitioned PID calculation in step S4 is performed after sampling, and the output duty cycle is refreshed to the PWM port driving the heating element via the controller. Zero-crossing detection generates a detection signal to notify the controller at the mains zero-crossing point. The live-line maintenance in step S6 only closes the AC power supply route via the HUB board's intelligent relay after confirming the mains zero-crossing point, ensuring arc suppression. Fault reporting is sent via a serial communication interface and is performed in a time-sharing manner with PID calculation, without blocking the main temperature control loop. This hardware execution link ensures that each step of the method is completed in a closed loop within a 500ms cycle. The four actions of switching, diagnosis, temperature control, and reporting do not preempt each other, meeting the real-time requirements of continuous stage operation.

[0028] To implement the above control method, the hardware implementation of each functional unit is as follows. The power supply hot backup unit is connected to two independent AC220V power supplies, one from the field mains power and the other from an online UPS (1500VA / 1200W). The two power supplies are introduced through SSR1, SSR2 (mains path) and SSR3, SSR4 (UPS path), respectively. The four SSRs are connected in series in the positive circuits of areas A and B, forming independent dual power supply switching channels for areas A and B. During normal operation, one SSR in the mains path is on and the other is off, while both SSRs in the UPS path are off for hot backup. The MCU continuously monitors the mains voltage. When the voltage drops below 180V or the power outage exceeds 20ms, it immediately performs a first-off-then-on switching: first, the on-conducting mains SSR is disconnected, and after a 5ms dead zone to ensure the main circuit capacitor discharges and the arc is extinguished, the corresponding UPS SSR is closed. The total switching time is no more than 15ms. A 1000µF / 400V electrolytic capacitor is connected in parallel on the DC bus side of both Zone A and Zone B to maintain the load terminal voltage above 200V during the dead zone, preventing the control board from resetting due to momentary interruptions. The SSR is selected with a rated current of 40A and an AC withstand voltage of not less than 480V; a 10D-9NTC is connected in series at the front end of the UPS output circuit to suppress start-up surges, and a TVS diode is connected in parallel on the DC bus to absorb turn-off spikes.

[0029] The voltage sustaining capability within the aforementioned switching dead zone can be quantitatively calculated based on three fundamental electrical relationships. The first is the AC rectification peak value relationship: after uncontrolled full-wave rectification of a single-phase AC circuit, the ideal DC bus voltage equals the AC effective value multiplied by the peak value factor. Therefore: In the formula The first line shows the nominal voltage of the DC bus after rectification; 220V is the AC RMS value. The second line shows the relationship between DC power and current. (Ohm's law in the power form under DC load), from which the load current can be solved inversely. Dead time is taken as... single zone rated power Take the average voltage of the bus. Substituting, we get: The third point is the definition of capacitor current. Within the dead zone, the load is maintained by the discharge of the bus capacitor, and the discharge current is approximately constant. For time from 0 integrals to Voltage drop: In the formula This refers to the capacitance value of the electrolytic capacitors connected in parallel to the busbar. To switch dead time, This represents the single-zone load current. Calculations show that the bus voltage drops only to approximately 308V from about 311V, far exceeding the design lower limit of 200V, leaving a margin of approximately 108V, ensuring the control board's power supply does not reset due to the momentary interruption. This derivation confirms that a 1000µF capacitance value is sufficient to maintain the 5ms dead time and provides a time window for establishing power supply to the UPS after the switchover is complete.

[0030] The total switching time budget is no more than 15ms, consisting of four segments: detection delay, disconnection of the original path, dead zone, and closure of the new path. The "disconnect before reconnect" requirement specifies a dead zone. It must be greater than the SSR turn-off tailing time and the bus residual voltage discharge time. The SSR turn-off tailing time is much smaller than the dead time, so take... This timing sequence ensures both complete shutdown of the original circuit and reliable extinguishing of the arc between contacts, with a remaining time of no more than 10ms for voltage detection and UPSSSR closure, meeting a total budget of no more than 15ms. This timing ensures that the micro-disruption time of the carbon fiber heating element is much smaller than its thermal inertia time constant, making the interruption imperceptible to both the naked eye and the temperature control loop.

[0031] The dual-zone heating unit consists of a heating prefabricated body that is physically divided to form two electrically isolated independent heating circuits (zone A and zone B). Each zone has a rated power of 200W, and the entire board has a rated power of 400W, serving as the controlled heating actuator. The specific construction of its physical division and isolation structure is described in the "Hardware Execution Carrier" section below.

[0032] Based on the aforementioned dual-zone structure, the system uses the temperature difference between Zone A and Zone B as the comparison quantity to implement cross-validation and graded protection. One 10kΩ@25℃ NTC is installed in each of Zones A and B (two NTCs in total), and the MCU samples the data via a 12-bit ADC at a 500ms cycle. The normal temperature difference is no greater than 3℃, and the alarm threshold is 8℃. The MCU determines an open circuit if the ADC reading is not less than 4090 and a short circuit if it is not greater than 10, and this condition must be met for three consecutive cycles (1.5s) to confirm a fault.

[0033] The above open-circuit and short-circuit criteria can be derived as follows: The NTC and the fixed pull-up resistor form a voltage divider network, with the voltage divider reference... ADC quantization follows a fundamental relationship: for 1-bit analog-to-digital converter, full-scale reference voltage Divided into equal parts Each quantized code corresponds to a voltage (quantization resolution) of: This system , Substitute into the above formula (source: (Definition of equal-interval quantization for a bit ADC) yields: In the formula, LSB represents the single-code voltage resolution. This is the ADC reference voltage. This refers to the number of conversion bits. NTC nominal resistance is 10kΩ at 25℃. When open-circuited, the resistance approaches infinity, and the voltage at the voltage divider point approaches... When the ADC reading approaches the full-scale range of 4095, an open circuit is determined if the reading is not less than 4095. During a short circuit, the resistance approaches 0Ω, the voltage at the voltage divider point approaches 0V, and the reading approaches 0. A short circuit is determined if the reading is not greater than 10 (corresponding to approximately 8mV, or about 10 LSBs). The mechanism of confirming through three consecutive sampling cycles is used to filter out transient fluctuations caused by electromagnetic interference, avoiding false triggering of the graded protection.

[0034] Upon fault confirmation, tiered protection is activated: a temperature difference exceeding 8°C triggers Level 1 power reduction (PWM limited to 70%); a single NTC failure triggers Level 2 (fault zone PWM limited to 30%); dual failures or temperatures exceeding 85°C trigger Level 3 hard cutoff and a red alarm. In Level 2 protection, the fault zone temperature is obtained through cross-estimation using the NTC temperature from another zone.

[0035] The cross-estimation is derived from the steady-state deviation between the two zones as defined in the pre-calibration coefficient table. For the same operating condition, zones A and B have an inherent temperature difference under steady-state conditions. It is defined as the difference between the steady-state temperature of the fault region and the steady-state temperature of the normal region: In the formula , These represent the steady-state temperatures of the fault zone and the normal zone under this operating condition, respectively. Based on pre-calibration, the average steady-state temperature difference between the two zones for three operating conditions—full load, half load, and standby—is obtained. Approximately 1 to 3°C and stored in the lookup table. When one NTC circuit fails and the other is functioning normally, the measured temperature in the normal zone is... At that time, by rearranging terms according to the above definition of steady-state deviation, we obtain the formula for estimating the temperature of the fault zone: In the formula Real-time measured temperature in the normal zone. This is the deviation from the baseline obtained from the table under the same operating condition. This formula allows the fault zone to maintain operation with conservative settings even when the local sensor is lost. The cross-estimation of the fault zone temperature in the secondary protection relies on a pre-calibrated "dual-zone steady-state temperature difference—operating condition" table lookup: using the measured temperature of the current normal zone... Based on the baseline, superimposed with the baseline under the same operating conditions. ; The average steady-state temperature difference between the two zones under three operating conditions (full load, half load, and standby) is obtained based on pre-calibration and stored in a pre-stored lookup table. During runtime, the table is looked up according to the current PWM duty cycle interval index, avoiding the time delay introduced by real-time calculation. The fault identification time is determined by a continuous confirmation mechanism: a single NTC needs to meet the open circuit or short circuit criteria for confirmation for 3 consecutive sampling cycles (1.5s). Therefore, the longest delay from the occurrence of a fault to system confirmation is 1.5s. This delay, together with the 500ms sampling cycle, constitutes a balance between disturbance rejection and response speed, ensuring no false alarms while limiting the exposure window of dangerous operating conditions to within 1.5s.

[0036] In conjunction with temperature monitoring, independent temperature control and dynamic compensation are executed independently in each of the two zones. Temperature control employs independent PID controllers for zones A and B, with the output being a PWM duty cycle driving MOSFET or IGBT arrays. The PID control law originates from the standard proportional-integral-derivative control law in control theory, and its continuous-time form is: This system discretizes the data with a 500ms sampling period and uses the backward Euler method to replace integrals with summations and differentials with differences between adjacent periods (i.e., , The discrete-position PID formula is derived from the above continuous control law: In the formula For the first The difference between the dynamically set temperature and the measured temperature during the sampling period. This is the deviation from the previous cycle. , , These are proportional, integral, and differential gains, respectively. The controller output is limited and mapped to the PWM duty cycle. Because region B contains an edge heat dissipation area and has greater heat loss than region A, the proportional gain tuning for region B is slightly higher than that for region A (region A...). Area B ).

[0037] The source of dynamic compensation for edge heat dissipation can be further explained. The heat dissipation rate from the edge of a large-sized heat-generating surface to the environment is higher than that from the center; without compensation in steady state... Actual temperature difference between the two zones This reflects the heat loss at the edge of zone B. The source of the compensation amount lookup table is the pre-calibrated "dual-zone steady-state temperature difference - edge compensation amount" curve. This curve reflects the increasing / decreasing relationship between the dual-zone temperature difference and the required compensation amount—the greater the edge heat loss, the greater the measured temperature difference, and the greater the compensation amount required to eliminate this temperature difference. This curve is obtained through calibration: under steady-state conditions, the compensation amount is increased from zero in fixed steps and applied to the set temperature side of zone B. Each increase is followed by recording the temperature difference after the dual zones re-enter steady state. The compensation amount under this condition is obtained when the temperature difference converges to within the set criterion. Changing the operating condition and repeating the above process yields the curve. The measured temperature difference is then calculated according to this curve. Mapped to the set compensation amount that needs to be raised. This constitutes a dynamically set temperature: In the formula Set the temperature based on the base. To base on the actual temperature difference The compensation amount obtained from the lookup table is discretized from the above curve according to the temperature difference range and stored as a pre-stored lookup table. During operation, the compensation amount is obtained by looking up the table using the measured temperature difference as an index. This formula superimposes the compensation amount on the setpoint side rather than the output side before feeding it into the PID calculation, avoiding integral saturation and oscillation caused by directly superimposing the output. Basic setpoint temperature 90% power in the heating section, heat preservation section The system features a 45℃ standby temperature to prevent condensation; conditional integral separation to prevent saturation (integration pauses when the deviation is greater than 15℃, and resumes when it is less than 10℃); PWM clamping is maintained from 5% to 95%. Multi-segment temperature profiles are scheduled by the temperature control logic according to operating conditions: the heating segment rapidly approaches the set temperature with a 90% duty cycle, then enters the set temperature range and is maintained by the PID controller; upon receiving a maintenance command or entering standby mode, the set temperature drops to 45℃ to suppress surface condensation; during switching or fault triggering, it enters the power reduction or protection segment, and resumes operation after the fault is cleared. The aforementioned heating, heat preservation, and standby segments correspond sequentially to preheating before the performance, heat preservation during the performance, and standby anti-condensation after the performance, according to the performance session. Switching between the three operating conditions is controlled by the host computer command or local timing. Because the heating plate and LED beads are located on opposite sides of the insulation structure... The control target for the heating plate side is that the temperature inside the screen cavity must be lower than this control target. The 45℃ setting in the standby phase is designed to keep the temperature inside the screen cavity above the dew point temperature. The temperature control logic allows the temperature profiles under different performance conditions to be configurable and independent of each other.

[0038] When power switching is triggered, the power reduction unit synchronously reduces the PWM of areas A and B to 70%. The calculation basis for the actual heat output under this power reduction condition is as follows: The carbon fiber heating element has a positive temperature coefficient, and its resistance increases with temperature rise. Furthermore, the inherent losses in SSR conduction and the circuit cause the heat output to exhibit a non-linear relationship with the PWM duty cycle. The actual heat power is lower than the linearly calculated value based on the duty cycle. Let the duty cycle be... The corresponding actual heat output percentage is the measured percentage coefficient. The general relationship between the actual power under reduced power conditions is as follows: In the formula This is the rated power of the entire board. This is the measured coefficient for duty cycle versus heat output percentage. This coefficient is derived from pre-calibration: the overall heat output of the plate is calibrated under different duty cycles, and a duty cycle versus heat output percentage curve is obtained through fitting. In this embodiment... hour ,Will and Substituting into the above equation and expanding, we get: The range is not less than 240W (i.e., 60% of the rated power), which meets the dual constraints of the UPS's battery life and heating limit under power reduction conditions. The recovery conditions are that the main power supply recovers to greater than 190V and remains stable for more than 3 power frequency cycles (60ms), the temperature difference between the two zones returns to within 3℃, and then smoothly recovers from 70% to 100% with a 2s ramp to avoid current surges and sudden changes in light emission.

[0039] To achieve the above control and facilitate maintenance during performance breaks, the HUB board is located in the power supply box, integrating filtering, SSR drivers, fuses, and two sets of IP67 waterproof terminal blocks (dual-port). The main and backup control cards for zones A and B (4 cards in total) are connected via board-to-board connectors. The MCU resides on the control card; the HUB board is only responsible for power distribution and switching. When a control card malfunctions, it is reported via encoding. The HUB board's intelligent relay cuts off the AC power supply to that zone at the voltage zero-crossing point. Maintenance personnel can remove the faulty card on the DC side, insert the backup card, and relock it before the system takes over temperature control for that zone. The DC bus power supply to the heating surface is not interrupted during card replacement. During hot-swapping, the DC side pin headers are operated, and the AC side closes at the voltage zero-crossing point using zero-crossing detection to eliminate arcing. Faults are reported via RS485 and Modbus RTU with the format 0xFC[type][details]. For example, 0xFC0101 indicates a mains power failure, 0xFC0301 indicates an open NTC circuit in zone A, and 0xFC0401 indicates a temperature difference exceeding the limit between the two zones. Faults and statuses are transmitted externally via RS485 industrial bus in Modbus RTU frame format, with a unified encoding of 0xFC[Fault Type][Fault Details]: Fault types include mains power failure, UPS switching completion, NTC open circuit, dual-zone temperature difference exceeding limits, control card failure, and hard cutoff lockout; the details field indicates the zone (zone A is 01, zone B is 02) and level. The system normally reports a normal operating status code once per second; upon a fault, it immediately reports the fault and caches recent fault records for the host computer to poll.

[0040] Local visualization of the operating status is achieved by a status indicator unit. This unit, along with the aforementioned industrial bus interface, is located on the HUB board and includes three luminous indicator elements configured to indicate normal operation, degraded operation under warning, and hard disconnection in case of fault. This allows field personnel to directly determine the current operating level without opening the package or connecting to a host computer. The power supply terminals of all three indicator elements are connected to the DC bus side after the two power supplies are combined, rather than being drawn from a single AC input. Therefore, if any AC power supply is interrupted and switched over, the indicator function does not fail due to the power loss of that line. Field personnel can still determine the actual operating status after the switch based on the indicators, avoiding the misinterpretation of a single power loss as a complete machine shutdown.

[0041] As the hardware execution carrier for the aforementioned functional units, the heating plate has the following specifications: The heating element is made of carbon fiber prefabricated material. The entire unit consists of a power supply box, a hub board, heating units in zones A and B, and an outer frame. The physical division and isolation structure of the dual-zone heating units is as follows: the heating prefabricated material is CNC-carved to form a 3.0mm through-slit, dividing it into symmetrical zones A and B (each... The gap is filled with a 1.5mm UL94V-0 flame-retardant PC zigzag-shaped partition and sealed with epoxy resin to achieve physical and electrical isolation between the two zones. The 1.5mm PC partition has a zigzag-shaped slot, and after being inserted into the gap, the upper and lower ends are bonded to the substrate with high-temperature resistant epoxy resin. After curing, it forms a bending-resistant reinforcing beam, ensuring the flatness of the entire board under handling and installation vibration. The partition has a UL94V-0 flame-retardant rating, ensuring that abnormal temperature rise in one zone will not ignite adjacent zones. Each zone is laid with T700 carbon fiber filaments, arranged in parallel with a spacing of 5mm, and the ends are crimped with copper foil and reinforced with conductive silver paste. The density of this filament is determined by thermal field design to ensure uniform normal temperature distribution across the entire surface. Physical isolation eliminates the spread of hidden short circuits caused by scratches or moisture in the carbon fiber layer of one zone to adjacent zones, and allows for independent temperature control and independent diagnostics between zones A and B.

[0042] The installation relationship of the heating plate in the LED display cabinet is as follows: The heating plate is installed in the cabinet with the heating surface facing the inner cavity of the screen. It is separated from the side where the LED beads are located by the encapsulation layer of the heating element and the back plate of the module. The LED beads are located on the front of the module, while the heating surface is located on the back of the module. The two are not directly attached. The heating plate supplies heat to the inner cavity of the screen, so that the inner cavity of the screen is preheated under low temperature conditions and maintained above the dew point temperature under high humidity conditions. The uniform temperature distribution along the surface suppresses the difference between different areas of the screen. The layer structure of the heating element from bottom to top is as follows: 1.5mm magnesium alloy base plate, the surface of which is anodized and insulated, serving as structural support and heat dissipation layer; 0.2mm polyimide film insulation layer; 0.15mm T700 carbon fiber prepreg heating layer, which is cut into two independent circuits, A and B areas; 0.1mm tin-plated copper foil electrode layer, which is attached to the ends of the carbon fiber filaments with conductive silver paste; 0.5mm modified epoxy resin encapsulation protective layer. The total thickness of the heating element after stacking the above layers is approximately 2.45mm, which, together with the height of the power supply box, constitutes a total board thickness of 67.5mm. After vacuum lamination and 85℃ curing for 4 hours, the entire board must pass a 72-hour water immersion test and a 2500V withstand voltage test before it can be shipped from the factory.

[0043] Voltage maintenance during the power supply switching dead zone is achieved by an energy storage capacitor connected in parallel to the DC bus side. A 1000μF / 400V electrolytic capacitor is connected in parallel to each of Zone A and Zone B to maintain the load voltage at no less than 200V during the dead zone of the first-to-last switching, ensuring that the control board logic is not reset due to the switching. The solid-state relay array consists of four solid-state relays forming an H-bridge mutual backup topology. Two main control relays and two bypass relays are set in each of the mains power path and UPS path, respectively connected in series to the live wire circuits of Zone A and Zone B. Two relays in the same path are connected in parallel to shunt current to reduce the heat generation of a single relay. The rated voltage of each solid-state relay is no less than 480VAC and the rated current is 40A.

[0044] The UPS capacity and runtime calculation are as follows. A 1500VA / 1200W online UPS is selected, with a maximum power consumption of 360W to 400W per unit. At a full load of 400W, the built-in battery pack provides approximately 30 minutes of runtime. The runtime calculation is based on the law of conservation of energy: the battery's nominal energy... Inverter efficiency Converted into energy that can be released to the load The load is in power Consume this energy; by Transpose and Substituting the values, we get the battery life: In the formula The nominal energy of the battery pack. The values ​​for the inverter efficiency of an online UPS are illustrative (ranging from 0.85 to 0.90). The load power is used as the formula. It is clear from the formula that the UPS runtime is inversely proportional to the load power: when the load power is reduced from 400W to 248W to 260W due to power reduction, the runtime is correspondingly extended to approximately 46 to 48 minutes. The power reduction strategy has a quantifiable benefit in extending UPS runtime. This calculation shows that the 1500VA / 1200W capacity provides sufficient margin for the basic operation of a single enclosure under switching conditions, and the 10D-9NTC surge suppression and TVS spike absorption ensure the safety of components in the UPS output circuit under frequent switching.

[0045] The entire unit employs a common-mode inductor and X and Y safety capacitors at the power input to form an EMI filter, suppressing SSR high-frequency switching and external interference conducted along the power line. The MCU's low-voltage and heating element's high-voltage wiring are separated, and anti-interference wiring is used for analog temperature sampling, ensuring that NTC data acquisition still meets the anti-interference requirement of continuous three-cycle confirmation even under the high-voltage environment of the stage. The HUB board's AC / DC areas are separated by slots and isolation strips, and the IP67 terminal blocks are double-molded, ensuring the entire unit meets the electrical safety and protection standards for stage equipment. Dual independent power supplies and solid-state relay arrays with fail-before-make switching solve uninterrupted heating under single-circuit interruption; dual-zone physical electrical isolation provides a structural basis for zoned temperature control and fault isolation; dual-channel NTC cross-validation and three-level graded protection ensure safe operation under sensor failure; zoned PID and edge compensation ensure even heat distribution across large surfaces; power reduction addresses the battery life and lower limit of backup power supply operation; and the HUB's dual ports and zero-crossing hot-swappable design allow for live maintenance. The six components work together around the same heating plate. No single unit can achieve the overall effect of "uninterrupted heating even when power is interrupted, no loss of control even when sensor malfunctions occur, uneven heating over a large area, and no need to disconnect power for maintenance" when it exists alone. Their combination produces continuous operational reliability that cannot be achieved by superimposing a single method.

[0046] The above description is only a preferred embodiment of the present invention. All equivalent substitutions or transformations made in accordance with the concept of the present invention should fall within the protection scope of the present invention.

Claims

1. A dual-power supply thermal backup control method for a heating plate used in LED displays, characterized in that, The heating plate, featuring a hardware architecture with dual-power thermal backup, dual-zone independent temperature control, and dual-signal monitoring, includes the following steps: Simultaneously collect temperature and power supply voltage in both zones; Monitor the power supply voltage, perform a first-to-break switch when the main power supply drops or is interrupted, and maintain the load voltage by the energy storage capacitor during the switching dead zone. The system collects dual-zone temperatures and identifies hardware faults based on the dual-zone temperature difference and the open / short circuit criteria of a single-channel temperature sensor. It provides protection in a graded manner, and when a single-channel temperature sensor fails, it maintains degraded operation by cross-estimating the temperature of the other zone. Temperature control is implemented independently for each zone, and edge heat dissipation is compensated by referring to a table based on the temperature difference between the two zones. During power supply switching, the dual-zone synchronization is reduced to a limited duty cycle; The redundant interface unit supports hot-swapping of the control card and reports operating status and fault information to external systems.

2. The method according to claim 1, characterized in that, The synchronous acquisition step synchronously acquires the dual-zone temperature and power supply voltage via an analog-to-digital converter at a fixed period; the triggering condition for the first-to-disconnect and then-connect switching is that the power supply voltage drops below a set threshold or the power outage lasts for more than a set duration, the total switching time is not greater than the set upper limit, and the original solid-state relay in the conducting circuit is disconnected first, and the backup solid-state relay is closed after the dead zone.

3. The method according to claim 1, characterized in that, The steps of the graded protection method include: when the temperature difference between the two zones exceeds the alarm threshold, it enters the first level of power reduction; when a single temperature sensor fails, it enters the second level of current limiting; when both channels fail or the temperature exceeds the safety limit, it enters the third level of hard cutoff; the confirmation of a single temperature sensor failure requires multiple consecutive sampling cycles to meet the open circuit or short circuit criteria.

4. The method according to claim 1, characterized in that, The step of implementing independent temperature control for dual zones uses an independent temperature control instance to output a drive signal, and the edge heat dissipation compensation obtained from the lookup table is superimposed on the set temperature side and then sent to the temperature control calculation. Integral separation anti-saturation and duty cycle clamping are enabled. The step of reducing the duty cycle to the limit during power supply switching is restored to the rated value by ramping smoothly after the main power is restored. In the hot-swap step, the AC side closes the corresponding power supply route at the voltage zero crossing point by zero-crossing detection, so that the heating surface does not stop heating due to the interruption of the DC bus during the replacement of the control card.

5. A dual-power supply thermal backup control system for a heating plate used in LED displays, characterized in that, The system includes a power supply thermal backup unit, a dual-zone heating unit, a temperature monitoring unit, a zone temperature control unit, a power reduction unit, and a redundant interface unit. The power supply thermal backup unit connects to two independent AC power supplies and, in the event of a main power failure or interruption, switches the load to the backup power supply according to the principle of disconnecting first and then connecting, maintaining the load voltage with the help of an energy storage capacitor to ensure that heating is not interrupted due to a single power supply anomaly. The dual-zone heating unit is divided into two electrically isolated independent circuits to isolate single-zone faults. The temperature monitoring unit collects the temperatures of both zones and cross-verifies and identifies hardware faults based on the temperature difference between the two zones and the open / short circuit criteria of a single sensor. In the event of a single-zone failure, it maintains degraded operation by estimating the temperature of the other zone. The zone temperature control unit independently controls the temperature of the two zones and compensates for edge heat dissipation to maintain uniform temperature across the entire surface. The power reduction unit synchronously reduces the duty cycle of both zones to a limited level during power supply switching to ensure basic operation of the backup power supply. The redundant interface unit supports hot-swapping of the control card while it is powered on and reports status and faults, thereby achieving uninterrupted maintenance.

6. The system according to claim 5, characterized in that, The power supply hot backup unit includes a solid-state relay array and an energy storage capacitor connected in parallel to the DC bus side. Two independent AC power supplies are introduced into each heating circuit of the dual-zone heating unit through the solid-state relay array, so that when the main power supply drops or is interrupted, the original solid-state relay in the conducting circuit is disconnected first, and the backup solid-state relay is closed after passing through the dead zone to complete the switching.

7. The system according to claim 5, characterized in that, The dual-zone heating unit is formed by physically dividing a carbon fiber preform into two electrically isolated independent heating circuits. An insulating isolation structure is provided between the two circuits to prevent the hidden short circuit caused by scratches or moisture in the single-zone heating layer from spreading to the adjacent zone.

8. The system according to claim 5, characterized in that, The temperature monitoring unit includes a temperature sensor and a graded protection circuit, one of each of the two zones. The graded protection circuit is configured to handle faults in three levels: early warning power reduction, single-zone current limiting, and hard cut-off. When a single temperature sensor fails, the temperature of the fault zone is estimated by cross-estimation of the temperature of the other zone to maintain degraded operation.

9. The system according to claim 5, characterized in that, The partitioned temperature control unit is an independent temperature control instance for each of the two zones. The compensation amount obtained by looking up the heat loss coefficient table of the dual-zone temperature difference is superimposed on the set temperature side and then sent into the temperature control calculation to suppress the temperature difference across the entire area.

10. The system according to claim 5, characterized in that, The power reduction unit is configured to reduce the dual-zone synchronous duty cycle to a limited duty cycle during power supply switching or maintenance mode, and then smoothly restore it to the rated duty cycle by ramping after the main power is restored to stability. The redundant interface unit includes a dual-port waterproof terminal block and an industrial bus interface. During maintenance, the control card is inserted or removed on the DC side via the dual-port waterproof terminal block, and the AC side is closed at the zero-crossing point of the voltage by zero-crossing detection, so as to realize uninterrupted maintenance of the heating surface, and report the operating status and fault information via the industrial bus with a unified fault code.

11. The system according to claim 6, characterized in that, The redundant interface unit also includes a status indicator unit, which includes at least three light-emitting indicator elements. The power supply terminals of the three light-emitting indicator elements are all connected to the DC bus side, and the three light-emitting indicator elements are respectively configured to indicate three operating states: normal operation, warning and degraded operation, and fault hard disconnection.