Method for eliminating feed-out voltage of motor of tracking support

Abstract

The invention discloses a method for eliminating feed-out voltage of a motor of a tracking support, and the method comprises the steps: enabling the feed-out voltage to be formed at an input end of the motor after the feed-out voltage passes through a rotary speed reducer and a motor gear box, and enabling the feed-out voltage to damage a power circuit and a power chip component of a PCB (Printed Circuit Board) of a tracking controller, the onboard relay and the absorption resistor are connected in parallel in the driving circuit of the PCB, the absorption resistor is cut off through the onboard relay when the photovoltaic tracking support rotates and tracks normally, and the absorption resistor is input through the onboard relay when the photovoltaic tracking support stops tracking. The electric energy generated by the output voltage of the motor is converted into heat energy to be consumed through the absorption resistor, so that the energy is prevented from being fed back to the PCB side of the tracking controller to damage a power supply circuit and a power supply chip component of the PCB; according to the design of the onboard relay and the absorption resistor, the cost is low, the risk of resonance is avoided, and the stability and the reliability of a main circuit are not influenced at the same time.

Description

Technical Field

[0001] The invention relates to a method for eliminating a fed-out voltage of a motor of a tracking bracket. Background Art

[0002] In scenarios where photovoltaic tracking systems are installed in large photovoltaic power plants, when strong winds occur during the non-tracking period, the photovoltaic modules will shake due to wind-induced vibration, causing slight rotation of the torque beam. This rotation generates a feed-back voltage at the motor input after passing through the slewing reducer and motor gearbox. The feed-back voltage can damage the power circuit and power chip components on the tracking controller's PCB.

[0003] For the output voltage, the current protection circuit on the PCB absorbs power through an LC absorption circuit. This circuit is expensive and introduces additional noise to other parts of the circuit, affecting circuit stability and reliability. Furthermore, the resonant frequency of the LC circuit requires precise adjustment to ensure effective absorption of the output voltage. However, this adjustment process can be complex, and improper adjustment can affect the normal operation of the circuit. Summary of the Invention

[0004] The present invention solves the problem of motor output voltage caused by wind-induced vibration of photovoltaic tracking brackets by using a method of on-board relay + absorption resistor. Compared with the LC absorption circuit, by connecting the on-board relay and absorption resistor in parallel in the PCB drive circuit, the cost is lower, and there is no risk of resonance, and the stability and reliability of the main circuit will not be affected. The technical solutions adopted in the present invention are: A method for eliminating the output voltage of a motor of a tracking bracket, wherein an onboard relay and an absorption resistor are connected in parallel in a PCB drive circuit of the photovoltaic tracking bracket; When the photovoltaic tracking bracket rotates and tracks normally, the absorption resistor is cut off through the onboard relay; When the photovoltaic tracking bracket stops tracking, the absorption resistor is input through the on-board relay so that the electrical energy generated by the motor feed voltage is converted into heat energy through the absorption resistor and consumed, avoiding damage to the PCB power circuit and power chip components.

[0005] Furthermore, a wind speed threshold, a vibration amplitude threshold, an identification condition for a tracking controller to stop tracking instructions, and an action delay time are preset in the control system of the photovoltaic tracking bracket; When the control system is running, the wind speed sensor and vibration sensor monitor the ambient wind speed and the vibration of the photovoltaic module in real time, and transmit the data to the tracking controller. At the same time, the tracking controller monitors whether it is in the stop tracking state; When the wind speed reaches or exceeds the wind speed threshold and the vibration amplitude reaches or exceeds the vibration amplitude threshold, and the tracking controller is in the tracking stop state, the conditions for triggering the onboard relay to input the absorption resistor are met, and the tracking controller starts the action delay timing. After the delay ends, the tracking controller sends a closing signal to the onboard relay, causing the onboard relay to operate and connect the absorption resistor to the circuit; When the wind speed decreases below the threshold and the vibration amplitude decreases below the threshold, and the tracking controller restarts the tracking instruction, the tracking controller sends a disconnect signal to the onboard relay, cuts off the absorption resistor, and the control system returns to normal operation.

[0006] Furthermore, if the control system detects that the vibration duration is less than the preset short-term threshold after the wind speed and vibration amplitude reach the threshold, the tracking controller determines it as a short-term wind-induced vibration and does not trigger the onboard relay action; During the control process, the control system continuously monitors the status feedback signal of the onboard relay. If no normal feedback signal of the onboard relay status is received after the action command is issued or the onboard relay status feedback is abnormal, the tracking controller will determine it as a system failure, issue an alarm signal and record the fault information.

[0007] Furthermore, a voltage sensor is provided at the input end of the PCB board drive circuit. The voltage sensor monitors the voltage at the input end of the PCB board drive circuit in real time. When the input voltage exceeds a preset overvoltage multiple of the rated operating voltage of the PCB board, the voltage sensor sends an overvoltage signal to the protection circuit control unit. The protection circuit control unit activates the transient suppression diode within a preset overvoltage protection time after receiving the overvoltage signal, clamps the overvoltage within a safe range, and simultaneously cuts off the subsequent power supply path of the PCB board drive circuit and sends an overvoltage fault alarm signal to the tracking controller.

[0008] Furthermore, temperature sensors are provided at the absorption resistor, on-board relay and PCB board drive circuit. The temperature sensors monitor the temperature of these components in real time. When the temperature exceeds the set temperature threshold, the temperature sensor sends a temperature alarm signal to the protection circuit control unit, and the protection circuit control unit takes corresponding protection measures according to the severity of the temperature alarm signal.

[0009] Furthermore, if the temperature exceeds the threshold of 35-50°C, an early warning signal is issued and the system operating power is automatically reduced to reduce heat; When the temperature exceeds the threshold of 50°C, the control unit will issue an immediate warning according to the preset strategy. The tracking controller will upload the over-temperature protection signal to the photovoltaic power station SCADA, and display the over-temperature alarm on the SCADA system. At the same time, the tracking controller will automatically start the internal cooling fan based on the temperature value of the absorption resistor, and use the fan to dissipate heat and cool the absorption resistor. When the temperature drops below 30°C, the fan will stop running, and the tracking controller will upload the protection signal that the temperature has returned to normal to the photovoltaic power station SCADA, and display the elimination of the over-temperature alarm on the SCADA system.

[0010] The present invention has the following beneficial effects: When a photovoltaic tracker stops tracking and strong winds occur, the photovoltaic modules will shake due to wind-induced vibration, causing a slight rotation of the torque beam. After passing through the slewing reducer and motor gearbox, a feed-in voltage is generated at the motor input terminal. This feed-in voltage can damage the power circuit and power chip components on the tracking controller's PCB. By connecting an onboard relay and an absorption resistor in parallel in the PCB's drive circuit, the absorption resistor is removed through the onboard relay during normal tracking and switched on through the onboard relay when the photovoltaic tracker stops tracking. The absorption resistor converts the electrical energy generated by the motor's feed-in voltage into heat energy and dissipates it, preventing energy from being fed back to the tracking controller's PCB and damaging the PCB's power circuit and power chip components. This design of an onboard relay plus an absorption resistor is low-cost, does not introduce the risk of resonance, and does not affect the stability and reliability of the main circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a circuit diagram of the present invention.

[0012] illustrate: 1. KM is the onboard relay, which is soldered on the PCB of the tracking controller. R1 is the absorption resistor and E is the DC motor. 2. N1 and N2 are the output terminals of the tracking controller PCB board, which are connected to the input terminals M1 and M2 of the motor; 3. When the motor generates the output voltage, the motor, KM and R1 form a loop. DETAILED DESCRIPTION

[0013] The present invention will be further described below with reference to the accompanying drawings.

[0014] Scenario 1: Application under standard working conditions A 1P tracker system was installed in a small photovoltaic power station. Its slewing reducer had a holding torque of 20 kNm and a rated output torque of 3.6 kNm. The DC motor had a rated current of 2.5 A and a rated voltage of 24 V. In the control system for this photovoltaic tracker, the wind speed threshold was preset to 10 m / s, and the vibration amplitude threshold was set to 2 mm of PV module displacement. The tracking controller also specified the conditions for identifying a stop tracking command, and set a 2-second delay.

[0015] Under normal weather conditions, when the PV tracker is in tracking operation, the wind speed sensor measures a wind speed of 8 m / s, and the vibration sensor detects a PV panel vibration amplitude of 1 mm, both below the preset threshold. At this point, the onboard relay remains disconnected under the control of the tracking controller, the absorption resistor is removed, and the drive circuit drives the motor normally, ensuring that the PV tracker accurately tracks the sun's position.

[0016] When wind picks up at the photovoltaic power station, the photovoltaic trackers stop tracking. If the wind speed suddenly rises to 12 m / s, the PV panels will shake under wind-induced vibration, with the amplitude reaching 3 mm. The wind speed and vibration sensors transmit real-time data to the tracking controller. If both the wind speed and vibration amplitude exceed preset thresholds and the tracking controller is in the stopped tracking state, the trigger condition is activated, initiating a 2-second timer delay. Upon expiration of the delay, the tracking controller immediately issues a close command to the onboard relay, which instantly activates and connects the absorption resistor to the circuit. Based on the measured 48V output voltage and 2.5A rated motor current, the calculated absorption resistor value is 19.2Ω, and the power requirement is 120W. (Based on R=U / I, R=48V / 2.5A=19.2Ω, the designed absorption resistor value is 19.2Ω. P=I²×R=2.5²×19.2=120W. When selecting the absorption resistor, the power must be greater than 120W. Selecting a higher-power absorption resistor ensures design margin and operational safety.) The absorption resistor converts the output voltage energy generated by the motor into heat and dissipates it, effectively avoiding the risk of damage to the PCB power circuit and power chip components.

[0017] When the wind speed drops back to 8m / s, the vibration amplitude of the photovoltaic module is reduced to a displacement of 1mm, and the tracking controller issues the tracking command again, the tracking controller immediately instructs the onboard relay to disconnect, the absorption resistor is cut off, the system returns to the initial operating state, the drive circuit drives the motor normally again, and the photovoltaic tracking bracket restarts the tracking mode.

[0018] Scenario 2: Handling of transient wind-induced vibrations Taking this small photovoltaic power station as an example, during normal operation of the photovoltaic tracking system, a sudden, short burst of strong winds instantly surged to 12 m / s, shaking the photovoltaic panels with a vibration amplitude of 3 mm. However, the vibration lasted only one second, falling short of the preset short-term threshold of two seconds. The control system accurately identified this as a brief, wind-induced vibration and did not trigger the onboard relays. This cleverly avoided the risks of mechanical wear and electrical contact problems caused by frequent relay activation. The drive circuit continued to operate stably, ensuring the smooth operation of the photovoltaic tracking system.

[0019] Scenario 3: System Fault Diagnosis and Alarm Suppose, in the aforementioned small PV power plant, when a feed-in voltage condition occurs, the tracking controller issues a closing command to the onboard relay as specified, but fails to receive a normal relay status feedback signal within the specified time. Alternatively, the feedback signal indicates an abnormal relay status, such as failure to close when instructed to close or failure to open when instructed to open. In this case, the tracking controller immediately determines that a system fault has occurred. It uploads the onboard relay fault signal to the PV power plant's SCADA system and displays an alarm on the SCADA system. Upon receiving the alarm, maintenance personnel quickly arrive based on the recorded information and conduct a detailed inspection of the onboard relay and related circuits. They discover that the onboard relay coil is damaged and replace it. After a system reset, normal operation resumes.

[0020] Scenario 4: Overvoltage protection mechanism activated During another operation of this medium-sized PV power plant, the motor's output voltage exceeded a preset overvoltage multiple of the PCB board's rated operating voltage, for example, 1.2 times the rated operating voltage. The voltage sensor detected this overvoltage condition in real time and immediately sent an alert to the protection circuit control unit. The control unit, as required, activated the transient suppressor diode (TVS) within 5 milliseconds, clamping the voltage to a safe range. The voltage sensor then sent an overvoltage signal to the protection circuit control unit and an overvoltage fault alarm to the tracking controller. The tracking controller then uploaded the overvoltage protection signal to the PV plant's SCADA system, which also displayed an overvoltage alarm. Because the TVS diode had activated, the voltage was clamped to a safe range, eliminating the need for operator intervention.

[0021] Scenario 5: Temperature protection mechanism activated Also at this medium-sized PV power station, one summer day, the continuous operation of the PV tracking brackets, coupled with rising ambient temperatures, caused the temperature of the absorber resistor to rise to 55°C, exceeding the preset temperature threshold of 50°C. The temperature sensor detected this overtemperature condition in real time and sent an alarm signal to the protection circuit control unit. Based on the preset strategy, the control unit immediately issued an early warning. The tracking controller uploaded an overtemperature protection signal to the PV power station's SCADA system, and displayed an overtemperature alarm on the SCADA system. Simultaneously, the tracking controller automatically activated the internal cooling fan based on the absorber resistor's temperature reading, dissipating heat and cooling the absorber resistor. Once the temperature dropped below 30°C, the fan stopped, and the tracking controller uploaded a protection signal to the PV power station's SCADA system, indicating that the temperature had returned to normal. The SCADA system also displayed the clearing of the overtemperature alarm. Because the fan had already activated to dissipate heat, no intervention by maintenance personnel was required.

[0022] The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements can be made without departing from the principles of the present invention. These improvements should also be regarded as the scope of protection of the present invention.

Claims

1. A method for eliminating the output voltage of a motor of a tracking bracket, characterized in that: Connect the onboard relay and absorption resistor in parallel in the PCB drive circuit of the photovoltaic tracking bracket; When the photovoltaic tracking bracket rotates and tracks normally, the absorption resistor is cut off through the onboard relay; When the photovoltaic tracking bracket stops tracking, the absorption resistor is input through the on-board relay so that the electrical energy generated by the motor feed voltage is converted into heat energy through the absorption resistor and consumed, avoiding damage to the PCB power circuit and power chip components.

2. The method for eliminating the output voltage of the motor of the tracking bracket according to claim 1, characterized in that: Preset wind speed threshold, vibration amplitude threshold, identification condition of tracking controller stop tracking instruction and action delay time in the control system of photovoltaic tracking bracket; When the control system is running, the wind speed sensor and vibration sensor monitor the ambient wind speed and the vibration of the photovoltaic module in real time, and transmit the data to the tracking controller. At the same time, the tracking controller monitors whether it is in the stop tracking state; When the wind speed reaches or exceeds the wind speed threshold and the vibration amplitude reaches or exceeds the vibration amplitude threshold, and the tracking controller is in the tracking stop state, the conditions for triggering the onboard relay to input the absorption resistor are met, and the tracking controller starts the action delay timing. After the delay ends, the tracking controller sends a closing signal to the onboard relay, causing the onboard relay to operate and connect the absorption resistor to the circuit; When the wind speed decreases below the threshold and the vibration amplitude decreases below the threshold, and the tracking controller restarts the tracking instruction, the tracking controller sends a disconnect signal to the onboard relay, cuts off the absorption resistor, and the control system returns to normal operation.

3. The method for eliminating the output voltage of the motor of the tracking bracket according to claim 2, characterized in that: If the wind speed and vibration amplitude reach the threshold, and the control system detects that the vibration duration is less than the preset short-term threshold, the tracking controller determines it as a short-term wind-induced vibration and does not trigger the onboard relay action; During the control process, the control system continuously monitors the status feedback signal of the onboard relay. If no normal feedback signal of the onboard relay status is received after the action command is issued or the onboard relay status feedback is abnormal, the tracking controller will determine it as a system failure, issue an alarm signal and record the fault information.

4. The method for eliminating the output voltage of the motor of the tracking bracket according to claim 1, characterized in that: A voltage sensor is provided at the input end of the PCB board drive circuit. The voltage sensor monitors the voltage at the input end of the PCB board drive circuit in real time. When the input voltage exceeds a preset overvoltage multiple of the PCB board's rated operating voltage, the voltage sensor sends an overvoltage signal to the protection circuit control unit. After receiving the overvoltage signal, the protection circuit control unit activates the transient suppression diode within the preset overvoltage protection time to clamp the overvoltage within a safe range. At the same time, the subsequent power supply path of the PCB board drive circuit is cut off and an overvoltage fault alarm signal is sent to the tracking controller.

5. The method for eliminating the output voltage of the motor of the tracking bracket according to claim 1, characterized in that: Temperature sensors are installed at the absorption resistor, on-board relay and PCB board drive circuit to monitor the temperature of these components in real time. When the temperature exceeds the set temperature threshold, the temperature sensor sends a temperature alarm signal to the protection circuit control unit, and the protection circuit control unit takes corresponding protection measures according to the severity of the temperature alarm signal.

6. The method for eliminating the output voltage of the motor of the tracking bracket according to claim 5, characterized in that: If the temperature exceeds the threshold of 35-50°C, an early warning signal will be issued and the system operating power will be automatically reduced to reduce heat; When the temperature exceeds the threshold of 50°C, the control unit will issue an immediate warning according to the preset strategy. The tracking controller will upload the over-temperature protection signal to the photovoltaic power station SCADA, and display the over-temperature alarm on the SCADA system. At the same time, the tracking controller will automatically start the internal cooling fan based on the temperature value of the absorption resistor, and use the fan to dissipate heat and cool the absorption resistor. When the temperature drops below 30°C, the fan will stop running, and the tracking controller will upload the protection signal that the temperature has returned to normal to the photovoltaic power station SCADA, and display the elimination of the over-temperature alarm on the SCADA system.

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