Contact resistance acquisition circuit of photovoltaic relay contact

Abstract

The utility model provides a contact resistance acquisition circuit of a photovoltaic relay contact. The contact resistance acquisition circuit comprises a controller, a power supply circuit and a test circuit. Wherein the test circuit comprises a low-resistance tester, four relay switches, a voltage sensor and two Kelvin clamps, the low-resistance tester comprises four test probes, a main clamping opening of one Kelvin clamp clamps one end of a main contact to be tested, a main clamping opening of the other Kelvin clamp clamps the other end of the main contact to be tested, and the test probes are connected with the relay switches. A test clamping opening and a reference clamping opening of the Kelvin clamp are connected with different relay switches respectively, different Kelvin clamps are connected with different relay switches, the four relay switches are connected with the four test probes in a one-to-one correspondence mode, and the voltage sensor is connected with a to-be-tested main contact in parallel. The controller controls the on and off of each relay switch in the test circuit according to the input acquisition signal, and detects the voltage. According to the utility model, the contact resistance of the photovoltaic relay contact can be acquired on the premise that the normal operation of a product is not influenced.

Description

Technical Field

[0001] The utility model belongs to the technical field of photovoltaic relay detection, and in particular relates to a photovoltaic relay contact resistance acquisition circuit. Background Art

[0002] In photovoltaic power generation systems, the contact resistance of string relays is a key factor affecting system stability and efficiency. While current test devices and circuits can perform basic relay testing, they have limitations, primarily in ensuring high-precision resistance measurement is compatible with normal product operation.

[0003] Existing devices and circuits often require powering down the system or causing some interference during the test when measuring the contact resistance of photovoltaic string relay contacts. This can affect normal operation and lead to inaccurate test data. This limits the practical application of these devices and circuits, especially in photovoltaic power generation systems that require high accuracy and reliability.

[0004] In order to solve these problems, it is urgent to develop a test device / circuit that can accurately measure the contact resistance of the string relay contacts without affecting the normal operation of the photovoltaic power generation system. Utility Model Content

[0005] The technical problem to be solved by the utility model is to provide a photovoltaic relay contact resistance acquisition circuit, so as to realize the acquisition of the contact resistance of the photovoltaic relay contact without affecting the normal operation of the product.

[0006] The photovoltaic relay contact resistance acquisition circuit provided by the utility model comprises a controller, a power supply circuit and a test circuit.

[0007] The test circuit is used to collect the contact resistance of the main contact to be tested, including a low resistance tester U1, a relay switch K01, a relay switch K02, a relay switch K03, a relay switch K04, a voltage sensor U0, a Kelvin clip C01, and a Kelvin clip C02. The low resistance tester U1 includes a test probe U11, a test probe U12, a test probe U13, and a test probe U14. The main clamp of the Kelvin clip C01 clamps one end of the main contact to be tested, the test clamp of the Kelvin clip C01 is connected to one end of the relay switch K01, and the other end of the relay switch K01 is connected to the test probe U1. 1. The reference clamp of Kelvin clamp C01 is connected to one end of relay switch K02, and the other end of relay switch K02 is connected to test probe U12. The main clamp of Kelvin clamp C02 clamps the other end of the main contact to be tested. The test clamp of Kelvin clamp C02 is connected to one end of relay switch K03, and the other end of relay switch K03 is connected to test probe U13. The reference clamp of Kelvin clamp C02 is connected to one end of relay switch K04, and the other end of relay switch K04 is connected to test probe U14. Voltage sensor U0 is connected in parallel with the main contact to be tested to collect the voltage across the main contact to be tested.

[0008] One end of the test circuit is connected to a first end of the controller, a power supply is connected to the other end of the test circuit and a second end of the controller, and a third end of the controller is grounded.

[0009] Optionally, the test circuit further includes a relay switch K1 connected in series between one end of the main contact to be tested and the voltage sensor U0.

[0010] Optionally, the power supply outputs 220V AC, 24V DC and 12V DC respectively.

[0011] Optionally, the controller outputs control signals of each relay switch in the photovoltaic relay contact resistance acquisition circuit respectively.

[0012] Optionally, the photovoltaic relay contact resistance acquisition circuit further includes a temperature control circuit, which includes a temperature sensor S1, a thermostat U2, an electric heater H1, and a fan F1;

[0013] The temperature sensor S1 is used to collect the ambient temperature around the photovoltaic relay contact resistance collection circuit and transmit the ambient temperature to the thermostat U2;

[0014] The thermostat U2 is used to send a control signal to the electric heater H1 or the fan F1 according to the ambient temperature to control the action of the electric heater H1 or the fan F1; the action is to start or shut down.

[0015] Optionally, 220V AC is input to the low resistance tester U1, the controller and the thermostat U2, 12V DC is input to the main contacts to be tested, and 24V DC is input to the voltage sensor U0.

[0016] Optionally, the controller is a single chip microcomputer or a PLC controller.

[0017] Optionally, the photovoltaic relay contact resistance acquisition circuit further includes an inductor KG, and the inductor KG is used to control the opening and closing of the relay switch corresponding to the main contact to be measured.

[0018] Optionally, the inductor KG is input with 12V DC output from the power supply circuit.

[0019] Optionally, flying wire welding is used to drive the opening and closing of the relay switch corresponding to the main contact to be tested.

[0020] The beneficial effects of the utility model are:

[0021] The photovoltaic relay contact resistance acquisition circuit employed in this utility model uses an external Kelvin clip to acquire the contact resistance of the main contacts to be measured, without affecting the normal operation of the photovoltaic relay. A controller controls the opening and closing of each relay in the test circuit, enabling interlock protection between the relay switches to ensure that they do not conflict or cause accidental operation during operation, thus ensuring accurate contact resistance acquisition. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic structural diagram of a photovoltaic relay contact resistance acquisition circuit in one embodiment of the present utility model;

[0023] Figure 2 This is a schematic structural diagram of a target photovoltaic string inverter in one embodiment of the present utility model;

[0024] Figure 3 This is a schematic diagram of the structure of a controller in one embodiment of the present utility model;

[0025] Figure 4 This is a schematic diagram of the structure of the power supply circuit in one embodiment of the present utility model;

[0026] Figure 5 This is a schematic structural diagram of a temperature control circuit in another embodiment of the present invention;

[0027] Figure 6 A schematic structural diagram of a photovoltaic relay contact resistance acquisition circuit provided by another embodiment of the present invention;

[0028] Among them, L represents the live wire and N represents the neutral wire. DETAILED DESCRIPTION

[0029] The utility model discloses a photovoltaic relay contact resistance acquisition circuit.

[0030] like Figure 1As shown, the photovoltaic relay contact resistance acquisition circuit includes a controller, a power supply circuit and a test circuit.

[0031] Among them, the test circuit is used to collect the contact resistance of the main contact to be tested, including a low resistance tester U1, a relay switch K01, a relay switch K02, a relay switch K03, a relay switch K04, a voltage sensor U0, a Kelvin clip C01, and a Kelvin clip C02. The low resistance tester U1 includes a test probe U11, a test probe U12, a test probe U13, and a test probe U14. The main clamp of the Kelvin clip C01 clamps one end of the main contact to be tested, the test clamp of the Kelvin clip C01 is connected to one end of the relay switch K01, and the other end of the relay switch K01 is connected to the test probe U11, the reference clamp of the Kelvin clip C01 is connected to one end of the relay switch K02, and the other end of the relay switch K02 is connected to the test probe U12. The main clamp of the Kelvin clip C02 clamps the other end of the main contact to be tested. The test clamp of the Kelvin clip C02 is connected to one end of the relay switch K03, and the other end of the relay switch K03 is connected to the test probe U13. The reference clamp of the Kelvin clip C02 is connected to one end of the relay switch K04, and the other end of the relay switch K04 is connected to the test probe U14. The voltage sensor U0 is connected in parallel with the main contact to be tested and is used to collect the voltage across the main contact to be tested.

[0032] One end of the test circuit is connected to a first end of the controller, a power supply is connected to the other end of the test circuit and a second end of the controller, and a third end of the controller is grounded.

[0033] Specifically, relay switches K01, K02, K03, and K04 are all master isolation relays, ensuring safety when connecting a low-resistance tester. When relay switches K01, K02, K03, and K04 are disconnected, the test circuit is safely de-energized, preventing potential circuit damage and ensuring operational safety when connecting the low-resistance tester U1.

[0034] When the main isolation relay switches (relay switch K01, relay switch K02, relay switch K03 and relay switch K04) are closed and the relays corresponding to the main contacts to be tested are closed, the low resistance tester U1 can collect the contact resistance on the main contacts to be tested.

[0035] It is worth mentioning that in this embodiment, a four-wire resistance test method is adopted, and the Kelvin clamp can effectively ensure the test accuracy; the contact resistance of the main contact to be tested is collected by an external Kelvin clamp and flying wire welding is used to drive the opening and closing of the relay switch corresponding to the main contact to be tested. The normal operation of the photovoltaic relay is not affected during the resistance collection period.

[0036] It should be noted that, in this embodiment, the main contact to be tested is any internal grid-connected relay of the target photovoltaic string inverter. Figure 2 The target photovoltaic string inverter has multiple internal grid-connected relays (internal grid-connected relay K11, internal grid-connected relay K12, internal grid-connected relay K21, internal grid-connected relay K22, internal grid-connected relay K31, and internal grid-connected relay K32). Multiple internal grid-connected relays are connected in series in groups of two (internal grid-connected relay K11 and internal grid-connected relay K12 form a group, internal grid-connected relay K21 and internal grid-connected relay K22 form a group, and internal grid-connected relay K31 and internal grid-connected relay K32 form a group). Internal grid-connected relays in different groups are connected in parallel. In the target photovoltaic string inverter, the inverter, filter, and each group of internal grid-connected relays are connected in series in sequence and then connected to the power grid.

[0037] The controller is used to receive the acquisition signal input by the user, control the opening and closing of each relay switch in the photovoltaic relay contact resistance acquisition circuit according to the acquisition signal, and detect the voltage. In this embodiment, the controller is a single chip microcomputer or a PLC controller. Figure 3 When the controller is a single-chip microcomputer, it has output ports that correspond to each relay switch in the test circuit. By controlling the opening and closing of each relay switch in the test circuit through the controller, interlock protection can be set up between the relay switches to ensure that the relay switches do not conflict with each other or cause accidental operation during operation, thereby ensuring the accuracy of contact resistance acquisition.

[0038] Specifically, the output port DO_1 corresponds to the relay switch main isolation relay switch K0 , and the output port DO_1 can control the relay switch K01 , the relay switch K02 , the relay switch K03 , and the relay switch K04 to be closed or opened at the same time.

[0039] Output ports DO_2 to DO_7 control the closing or opening of the internal grid-connected relay K11 , the internal grid-connected relay K12 , the internal grid-connected relay K21 , the internal grid-connected relay K22 , the internal grid-connected relay K31 , and the internal grid-connected relay K32 , respectively.

[0040] The MCU also has an input port Vi for detecting the voltage across the main contact to be tested. Voltage sensor U0 inputs the detected voltage into the MCU through input port Vi, and the MCU then detects the input voltage value. For example, when a low-resistance tester U1 is connected, if voltage is present, the main isolation relay switch is controlled to open to prevent damage to the low-resistance tester U1. When collecting contact resistance, if the voltage is too high, the main isolation relay switch is controlled to open to ensure the safety of testers and equipment.

[0041] In this embodiment, reference Figure 4The power supply circuit outputs 220V AC, 12V DC, and 24V DC. The 220V AC is input to the low resistance tester U1 and the controller, the 12V DC is input to the main contact to be tested, and the 24V DC is input to the voltage sensor U0.

[0042] In another embodiment, to ensure circuit safety, the test circuit also includes a relay switch K1 connected in series between one end of the main contact under test and the voltage sensor U0. Relay switch K1 controls whether voltage sensor U0 is connected to the test circuit. The controller also includes a door-opening detection switch K2, which detects whether the circuit is connected or disconnected to ensure the safety and correctness of the circuit connection. The photovoltaic relay contact resistance acquisition circuit also includes an inductor KG, which is used to control the opening and closing of the relay switch corresponding to the main contact under test, further minimizing the impact on the operation of the target photovoltaic string inverter.

[0043] In one embodiment, in order to avoid the influence of ambient temperature on resistance acquisition, the photovoltaic relay contact resistance acquisition circuit further includes a temperature control circuit. Figure 5 The temperature control circuit includes a temperature sensor S1, a thermostat U2, an electric heater H1, and a fan F1. Temperature sensor S1 is used to collect the ambient temperature surrounding the photovoltaic relay contact resistance acquisition circuit and transmit the ambient temperature to thermostat U2. Thermostat U2 sends a control signal to the electric heater H1 or fan F1 based on the ambient temperature, controlling their operation. Specifically, when the detected temperature is below 20°C, the electric heater H1 and fan F1 are activated. When the temperature reaches 35°C, the electric heater H1 and fan F1 are controlled to stop heating and rotating. When the temperature inside the cabinet exceeds 45°C, fan F1 is activated to ensure that the instrument and controller are not affected by the ambient temperature and test accuracy.

[0044] At this time, the 220V AC output of the power supply circuit is respectively input to the low resistance tester U1, the controller and the thermostat U2 (used by the thermostat to control the electric heater H1 to start heating), the 12V DC is input to the main contact to be tested, and the 24V DC is input to the voltage sensor U0 and the fan F1 (used by the thermostat to control the rotation of the fan F1). In this embodiment, the photovoltaic relay contact resistance acquisition circuit is as follows: Figure 6 shown.

[0045] As can be seen from the above, the photovoltaic relay contact resistance acquisition circuit employed in this utility model uses an external Kelvin clip to acquire the contact resistance of the main contacts to be measured, without affecting the normal operation of the photovoltaic relay. Furthermore, a controller controls the opening and closing of each relay in the test circuit, enabling interlock protection between the relay switches to ensure that the relay switches do not conflict or cause accidental operation during operation, thus ensuring the accuracy of contact resistance acquisition.

[0046] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of protection of the present application is limited to these examples. In line with the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0047] The one or more embodiments of this application are intended to encompass all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this application should be included in the scope of protection of this application.

Claims

1. A photovoltaic relay contact resistance acquisition circuit, including a controller and a power supply circuit, characterized in that: Also included is a test circuit; The test circuit is used to collect the contact resistance of the main contact to be tested, including a low resistance tester U1, a relay switch K01, a relay switch K02, a relay switch K03, a relay switch K04, a voltage sensor U0, a Kelvin clip C01, and a Kelvin clip C02. The low resistance tester U1 includes a test probe U11, a test probe U12, a test probe U13, and a test probe U14. The main clamp of the Kelvin clip C01 clamps one end of the main contact to be tested, the test clamp of the Kelvin clip C01 is connected to one end of the relay switch K01, and the other end of the relay switch K01 is connected to the test probe U11. The reference clamp of K01 is connected to one end of the relay switch K02, the other end of the relay switch K02 is connected to the test probe U12, the main clamp of the Kelvin clamp C02 clamps the other end of the main contact to be tested, the test clamp of the Kelvin clamp C02 is connected to one end of the relay switch K03, the other end of the relay switch K03 is connected to the test probe U13, the reference clamp of the Kelvin clamp C02 is connected to one end of the relay switch K04, the other end of the relay switch K04 is connected to the test probe U14, and the voltage sensor U0 is connected in parallel with the main contact to be tested, for collecting the voltage across the main contact to be tested; One end of the test circuit is connected to a first end of the controller, the power supply is connected to the other end of the test circuit and a second end of the controller, and a third end of the controller is grounded.

2. The photovoltaic relay contact resistance acquisition circuit according to claim 1, characterized in that: The test circuit further includes a relay switch K1 connected in series between one end of the main contact to be tested and the voltage sensor U0 .

3. The photovoltaic relay contact resistance acquisition circuit according to claim 1, characterized in that: The power supply outputs 220V AC, 24V DC and 12V DC respectively.

4. The photovoltaic relay contact resistance acquisition circuit according to claim 1, characterized in that: The controller outputs control signals of the relay switches in the photovoltaic relay contact resistance acquisition circuit respectively.

5. The photovoltaic relay contact resistance acquisition circuit according to claim 3, characterized in that: It also includes a temperature control circuit, which includes a temperature sensor S1, a thermostat U2, an electric heater H1, and a fan F1; The temperature sensor S1 is used to collect the ambient temperature around the photovoltaic relay contact resistance collection circuit and transmit the ambient temperature to the thermostat U2; The thermostat U2 is used to send a control signal to the electric heater H1 or the fan F1 according to the ambient temperature to control the action of the electric heater H1 or the fan F1; the action is to start or shut down.

6. The photovoltaic relay contact resistance acquisition circuit according to claim 5, characterized in that: The 220V AC power is respectively input into the low resistance tester U1, the controller and the temperature controller U2, the 12V DC power is input into the main contact to be tested, and the 24V DC power is input into the voltage sensor U0.

7. The photovoltaic relay contact resistance acquisition circuit according to claim 1, characterized in that: The controller is a single chip microcomputer or a PLC controller.

8. The photovoltaic relay contact resistance acquisition circuit according to claim 6, characterized in that: It also includes an inductor KG, which is used to control the opening and closing of the relay switch corresponding to the main contact to be tested.

9. The photovoltaic relay contact resistance acquisition circuit according to claim 8, characterized in that: The inductor KG is input with the 12V DC power output by the power supply circuit.

10. The photovoltaic relay contact resistance acquisition circuit according to claim 1, characterized in that: Flying wire welding is used to drive the opening and closing of the relay switch corresponding to the main contact to be tested.

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