Power unit control circuit and frequency converter

Abstract

The utility model provides a power unit control circuit and a frequency converter, the power unit control circuit comprises a power supply, a soft start power supply sub-circuit, a detection sub-circuit, an output sub-circuit and a control unit, the power supply is respectively connected with the control unit, the soft start power supply sub-circuit and the detection sub-circuit; the detection sub-circuit is respectively connected with the control unit and the output sub-circuit; the control unit is connected with the power unit; and the soft start power supply sub-circuit, the power unit and the output sub-circuit are connected in sequence. According to the embodiment of the utility model, the transformer boosts the 380V voltage of the power supply for power supply, so that the environmental requirements of detection are met, and the convenience of detection is improved; the detection sub-circuit is directly connected with the control unit so that detected voltage and current information can be quickly fed back to the control unit, the control unit can select corresponding actions according to transmitted information, the control circuit is simplified, the resource utilization rate is improved, and the detection response speed of the current and the voltage is increased.

Description

Technical Field

[0001] This utility model relates to the field of power electronics technology, and in particular to a power unit control circuit and frequency converter. Background Technology

[0002] With the rapid development of the energy industry, medium and high voltage frequency converters are now widely used in various fields, such as shipbuilding, metallurgy, natural gas, and mining. Frequency converters of different capacities and manufacturers basically all include rectification and inversion functions. As the performance requirements of equipment continue to increase, how to ensure the safe operation of the frequency converter power unit and the detection and monitoring of its operating status while ensuring performance is a huge challenge.

[0003] Currently, most inverters on the market suffer from problems such as excessively high current or voltage generated by the power unit after long-term use, or the power unit malfunctioning during inverter assembly, leading to inverter failure or even explosion. Existing methods for detecting current and voltage generally rely on the platform's 690V power supply for power supply testing, which limits the testing location, and the testing circuits are generally quite complex (such as using probes, oscilloscopes, etc.) and have low testing efficiency. Utility Model Content

[0004] This utility model provides a power unit control circuit and a frequency converter, aiming to solve the problems of existing frequency converter power unit control circuits having limited detection environment due to power supply issues, and being too complex and having low detection efficiency.

[0005] To address the aforementioned technical problems, this utility model provides a power unit control circuit. The power unit detection circuit includes a power supply, a control unit, a soft-start power supply sub-circuit, a detection sub-circuit, and an output sub-circuit. The power supply is connected to the control unit, the soft-start power supply sub-circuit, and the detection sub-circuit. The detection sub-circuit is connected to the control unit and the output sub-circuit. The control unit is connected to the power unit. The soft-start power supply sub-circuit, the power unit, and the output sub-circuit are connected sequentially.

[0006] Furthermore, the soft-start power supply sub-circuit includes a power input switch, a pre-charge unit, and a transformer connected in series.

[0007] Furthermore, the pre-charge unit includes a pre-charge resistor and a first contactor connected in parallel.

[0008] Furthermore, the detection sub-circuit includes a voltage detection sub-circuit and a current detection sub-circuit.

[0009] Furthermore, the voltage detection sub-circuit includes a resistor divider and a voltage sampling board, and the current detection sub-circuit includes a Hall sensor and a current sampling board.

[0010] Furthermore, the control unit includes a DIO board, relay one, relay two, relay three and relay four. The DIO board includes a DI1 port, a DO1 port, a DI2 port and a DO2 port. The DI1 port is connected to relay one, the DO1 port is connected to relay two, the DI2 port is connected to relay three, and the DO2 port is connected to relay four.

[0011] Furthermore, the output sub-circuit includes a second contactor and a filter unit connected in series, and the output terminal of the output sub-circuit is connected to the load.

[0012] Furthermore, the filtering unit includes a filtering inductor and a filtering capacitor, the front end of the second contactor is connected to one end of the voltage detection sub-circuit, and the front end of the load is connected to one end of the current detection sub-circuit.

[0013] Furthermore, the control unit is connected to the power unit via an optical fiber.

[0014] According to another aspect of this application, the present invention provides a frequency converter, which includes the power unit control circuit described above.

[0015] This invention proposes a power unit control circuit and a frequency converter. The power unit control circuit includes a power supply, a control unit, a soft-start power supply sub-circuit, a detection sub-circuit, and an output sub-circuit. The power supply is connected to the control unit, the soft-start power supply sub-circuit, and the detection sub-circuit. The detection sub-circuit is connected to the control unit and the output sub-circuit. The control unit is connected to the power unit. The soft-start power supply sub-circuit, the power unit, and the output sub-circuit are connected sequentially, and the output signal of any one level unit serves as the input signal for the next adjacent level unit. In this embodiment, a transformer boosts the 380V power supply, meeting the environmental requirements for detection and improving the convenience of detection. The soft-start power supply sub-circuit, the power unit, and the detection sub-circuit are directly connected to the control unit, allowing for rapid feedback of detected voltage and current information. The control unit then selects and performs corresponding actions based on the transmitted information. This invention simplifies the control circuit, improves resource utilization, and accelerates the detection response speed of current and voltage. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1This is a schematic diagram of a power unit control circuit provided in an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of a DIO board circuit provided in one embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of a voltage detection sub-circuit provided in an embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of a current detection sub-circuit provided in one embodiment of the present invention.

[0021] The labels for the attached figures are as follows:

[0022] 1. Power supply; 2. Soft start power supply sub-circuit; 3. Precharge unit; 4. Power unit; 5. Control unit; 6. Detection sub-circuit; 7. Filtering unit; 8. Load; 9. Voltage detection sub-circuit; 10. Current detection sub-circuit; 11. Display; 12. Relay 1; 13. Relay 2; 14. DIO board; 15. Resistor voltage divider board; 16. Voltage sampling board; 17. Hall sensor; 18. Current sampling board; 20. Relay 3; 21. Relay 4; K. Power input switch; QF1. First contactor; QF2. Second contactor; R1. Precharge resistor; T. Transformer; L1. Filter inductor; C1. Filter capacitor. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0024] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0025] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0026] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0027] Please see Figure 1 , Figure 1 This is a schematic diagram of a power unit control circuit according to an embodiment of the present invention. The present invention proposes a power unit control circuit and a frequency converter. The power unit control circuit includes a power supply 1, a control unit 5, a soft-start power supply sub-circuit 2, a detection sub-circuit 6, and an output sub-circuit. The power supply is connected to the control unit 5, the soft-start power supply sub-circuit 2, and the detection sub-circuit 6 respectively; the detection sub-circuit 6 is connected to the control unit 5 and the output sub-circuit respectively; the control unit 5 is connected to a power unit 4; the soft-start power supply sub-circuit 2, the power unit 4, and the output sub-circuit are connected sequentially.

[0028] In this embodiment, the pre-charging resistor R1 of the soft-start power supply sub-circuit 2 can act as a buffer during the pre-charging process, preventing the power unit 4 from overheating due to excessive voltage rise. The transformer boosts the 380V power supply, meeting the environmental requirements for detection and improving the convenience of detection. The detection sub-circuit 6 is directly connected to the control unit 5, allowing for rapid feedback of the detected voltage and current information. The control unit 5 will then select and perform corresponding actions based on the transmitted information. The control circuit of this invention is simple, improves resource utilization, and accelerates the detection response speed of current and voltage.

[0029] Preferably, the control unit 5 is connected to the power unit 4 via an optical fiber. The control unit 5 can transmit data to the power unit 4 via the optical fiber. The control unit 5 can set a voltage threshold, control the waveform, and monitor the DC bus voltage in the power unit 4 in real time. When the DC bus voltage reaches the set threshold, it will also transmit the corresponding information to the control unit 5 via the optical fiber.

[0030] Preferably, the power supply 1 provides a voltage of 15V to the control unit 5 and the detection sub-circuit 6 respectively.

[0031] In one embodiment, such as Figure 1 As shown, the soft start power supply sub-circuit 2 includes a power input switch K, a pre-charge unit 3, and a transformer T connected in series.

[0032] In this embodiment, the soft starter power supply sub-circuit 2 includes a power input switch K, which can control the current switching of the overall circuit; the soft starter power supply sub-circuit 2 includes a pre-charge unit 3, specifically, the pre-charge unit 3 includes at least three pre-charge resistors R1 and at least one first contactor QF1, the pre-charge resistors R1 and the first contactor QF1 are connected in parallel, and the pre-charge resistors R1 are in a bypass state when the first contactor QF1 is closed; the soft starter power supply sub-circuit 2 includes a transformer T, specifically, the transformer T can establish magnetic flux inside when working, the left side of the transformer T is the primary side and the right side is the secondary side.

[0033] Preferably, the primary side input voltage of the transformer T is 380V, and the secondary side output voltage is generally 690V. The secondary side output voltage of the transformer T can be selected according to the working requirements of the power unit.

[0034] In one embodiment, such as Figure 1 As shown, the detection sub-circuit 6 includes a voltage detection sub-circuit 9 and a current detection sub-circuit 10.

[0035] In this embodiment, as Figure 3 As shown, the detection sub-circuit 6 includes a voltage detection sub-circuit 9; specifically, the voltage detection sub-circuit 9 includes a resistor divider plate 15 and a voltage sampling plate 16. Multiple resistors on the resistor divider plate 15 are connected in series, and the voltage is distributed according to the resistance ratio of the resistors to achieve the circuit's voltage reduction function. The voltage sampling plate 16 can collect AC voltage data from the circuit and then transmit the AC voltage data to the control unit 5. Figure 4 As shown, the detection sub-circuit 6 further includes a current detection sub-circuit 10; specifically, the current detection sub-circuit 10 includes a Hall sensor 17 and a current sampling board 18. The Hall sensor 17 can convert changes in the magnetic field into electrical signals to achieve accurate measurement and control of the magnetic field; the current sampling board 18 can collect current data in the circuit and then transmit the collected current data to the control unit 5.

[0036] In one embodiment, such as Figure 2 As shown, the control unit includes a DIO (Digital Input / Output Board) 14, a relay 12, a relay 23, a relay 30, and a relay 41. The DIO board includes a DI1 port, a DO1 port, a DI2 port, and a DO2 port. The DI1 port is connected to the relay 12, the DO1 port is connected to the relay 23, the DI2 port is connected to the relay 30, and the DO2 port is connected to the relay 41.

[0037] In this embodiment, the coil of relay 12 is connected in series with the auxiliary contact circuit of the first contactor QF1, and the contacts of relay 12 are connected in series with the circuit of DI1. The coil of relay 13 is connected in series with the circuit of DO1, and the contacts of relay 13 are connected in series with the coil of the first contactor QF1. The DIO board can control the opening and closing of the contactor QF1 through relay 13. When the DO1 port of the DIO board 14 sends a high-level signal, the contacts of relay 13 close, and the coil of the first contactor QF1 is energized and thus closes. When the DO1 port of the DIO board 14 sends a low-level signal, the contacts of relay 13 open, and the coil of the first contactor QF1 is de-energized and thus opens.

[0038] like Figure 2 As shown, the DIO board 14 can also detect the operating state of the first contactor QF1 through the second relay 13. When the contacts of the first contactor QF1 are open or closed, the coil of the second relay 13 will be de-energized or energized, so that the contacts of the second relay 13 will be open or closed. The DI1 port of the DIO board 14 is connected to the contacts of the second relay 13, and can detect the operating state of the first contactor QF1.

[0039] Specifically, the control of the second contactor QF2 is the same as that of the first contactor QF1.

[0040] In one embodiment, such as Figure 1 As shown, the output sub-circuit includes a second contactor QF2 connected in series with a filter unit 7, and the output terminal of the output sub-circuit is connected to the load.

[0041] In this embodiment, the output sub-circuit includes a second contactor QF2. When the second contactor QF2 is closed, the power unit 4 can be normally connected to the load 8, thereby outputting current. When the second contactor QF2 is open, the power unit 4 cannot output current to the load 8. The output sub-circuit includes a filter unit 7. The filter unit 7 can perform modulation, demodulation, noise reduction, and other processing on the signal transmitted from the power unit 4 before transmitting it to the load 8.

[0042] Specifically, the filtering unit 7 includes a filtering inductor L1 and a filtering capacitor C1, the front end of the second contactor QF2 is connected to one end of the voltage detection sub-circuit 9, and the front end of the load 8 is connected to one end of the current detection sub-circuit 10.

[0043] Preferably, the power unit control circuit further includes a display 11, which can display parameters such as the output voltage, output current and DC bus voltage of the power unit control loop.

[0044] In one embodiment, a frequency converter is provided, the frequency converter including the power unit control circuit described above.

[0045] Specifically, the working principle of the power unit control circuit is as follows:

[0046] After the power supply 1 is turned on, the power unit control circuit is energized. At this time, both the first contactor QF1 and the second contactor QF2 are in the open state, and the power unit 4 performs pre-charging. When the DC bus voltage in the power unit 4 reaches the threshold, the control unit 5 controls the first contactor QF1 to close. At this time, the pre-charging resistor R1 is bypassed, and the power unit 4 switches to direct charging. During pre-charging, disconnecting the first contactor QF1 to connect the pre-charging resistor R1 to the circuit is to reduce the inrush current inside the transformer T and reduce the impact on the power unit devices. When the DC bus voltage reaches the threshold, switching to direct charging will not impact the power unit devices, and it can also avoid the problem of high heat generated by the pre-charging resistor R1 working for a long time.

[0047] When the voltage detection subcircuit 9 detects that the output voltage meets the rated voltage value, the control unit 5 controls the second contactor QF2 to close, starting to output power to the load 8. When the voltage detection subcircuit 9 detects that the output voltage fluctuation exceeds 10%, or the current detection subcircuit 10 detects that the output current reaches 120% or more of the rated current, the voltage detection subcircuit 9 or the current detection subcircuit 10 will transmit abnormal information to the control unit 5. The control unit 5 will immediately stop sending signals to the power unit 4, and simultaneously control the second contactor QF2 to open and shut off the power supply 1. The power unit control circuit and the frequency converter will then stop working. The working mechanism of the detection subcircuit 6 avoids the problem of the frequency converter continuing to work when the power unit output current or output voltage is unstable, which could cause the control circuit and power unit devices to overheat or even burn out, effectively ensuring the safety of equipment operation.

[0048] This invention proposes a power unit control circuit and a frequency converter. The power unit control circuit includes a power supply 1, a control unit 5, a soft-start power supply sub-circuit 2, a detection sub-circuit 6, and an output sub-circuit. The power supply 1 is connected to the control unit 5, the soft-start power supply sub-circuit 2, and the detection sub-circuit 6. The detection sub-circuit 6 is connected to the control unit 5 and the output sub-circuit. The control unit 5 is connected to the power unit 4. The soft-start power supply sub-circuit 2, the power unit 4, and the output sub-circuit are connected sequentially. In this embodiment, the pre-charging resistor R1 of the soft-start power supply sub-circuit 2 acts as a buffer during the pre-charging process, preventing the power unit 4 from overheating due to excessive voltage rise. The transformer boosts the 380V power supply, meeting the environmental requirements for detection and improving the convenience of detection. The detection sub-circuit 6 is directly connected to the control unit 5, allowing for rapid feedback of detected voltage and current information. The control unit 5 then selects and performs corresponding actions based on the transmitted information. This invention features a simple control circuit, improved resource utilization, and faster response speed for current and voltage detection.

[0049] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this utility model, and these modifications or substitutions should all be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A power cell control circuit, characterized by The power unit control circuit comprises a power supply, a soft start power supply sub-circuit, a detection sub-circuit, an output sub-circuit and a control unit, the power supply is connected with the control unit, the soft start power supply sub-circuit and the detection sub-circuit respectively, the detection sub-circuit is connected with the control unit and the output sub-circuit respectively, the control unit is connected with the power unit, and the soft start power supply sub-circuit, the power unit and the output sub-circuit are connected in sequence.

2. The power cell control circuit of claim 1, wherein, The soft start power supply sub-circuit comprises a power input switch, a pre-charging unit and a transformer connected in sequence.

3. The power cell control circuit of claim 2, wherein, The pre-charging unit comprises a pre-charging resistor and a first contactor connected in parallel.

4. The power cell control circuit of claim 1, wherein, The detection sub-circuit comprises a voltage detection sub-circuit and a current detection sub-circuit.

5. The power cell control circuit of claim 4, wherein, The voltage detection sub-circuit comprises a resistance voltage divider and a voltage sampling board, and the current detection sub-circuit comprises a Hall sensor and a current sampling board.

6. The power cell control circuit of claim 1, wherein, The control unit comprises a DIO board, a relay one, a relay two, a relay three and a relay four, the DIO board comprises a DI1 port, a DO1 port, a DI2 port and a DO2 port, the DI1 port is connected with the relay one, the DO1 port is connected with the relay two, the DI2 port is connected with the relay three, and the DO2 port is connected with the relay four.

7. The power cell control circuit of claim 1, wherein, The output sub-circuit comprises a second contactor and a filter unit connected in series, and an output end of the output sub-circuit is connected with a load.

8. The power cell control circuit of claim 4, wherein, The output sub-circuit comprises a second contactor and a filter unit connected in series, the filter unit comprises a filter inductor and a filter capacitor, a front end of the second contactor is connected with one end of the voltage detection sub-circuit, and one end of the current detection sub-circuit is connected with a front end of a load.

9. The power cell control circuit of claim 1, wherein, The control unit is connected with the power unit through an optical fiber.

10. A frequency converter, characterized in that The frequency converter comprises the power unit control circuit of any one of claims 1-9.

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