Frequency converter three-phase input open-phase detection method and system

Abstract

The invention provides a frequency converter three-phase input open-phase detection method and system, the method is applied to the frequency converter three-phase input open-phase detection system, the system comprises a three-phase rectification circuit, in the three-phase rectification circuit, three diodes D1, D2 and D3 form a common-cathode three-phase half-wave rectification, three diodes D4, D5 and D6 form a common-anode three-phase half-wave rectification, and the three diodes D1, D2 and D3 form a common-anode three-phase half-wave rectification. The switch J1 and the resistor R form a buffer relay, rectified current passes through the closed switch J1 and the inductor L and then charges the capacitors C1 and C2, the capacitor C1 and the capacitor C2 are connected in series and then supply direct current to a load, and voltage at two ends of the capacitor C1 and the capacitor C2 after the capacitor C1 and the capacitor C2 are connected in series is bus voltage. And if it is determined that the bus voltage ripple zero crossing point change frequency is less than a set frequency threshold value within a preset time, determining that three-phase power supply is lacked. The open-phase state of the power supply can be detected without additionally adding hardware.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic equipment, and in particular to a method and system for detecting phase loss in three-phase input of a frequency converter. Background Art

[0002] With the development of power electronics technology, three-phase power grids are prone to phase loss in high-voltage and complex working environments. If the phase loss fault is not detected in time or the detection and elimination time is long, it will damage the subsequent related power equipment and cause serious economic and property losses.

[0003] However, the traditional method of detecting phase failure in power grid mainly relies on manual troubleshooting, which is time-consuming and labor-intensive, and the detection is not timely. It is unable to respond quickly to changes in the power grid and has a large delay problem.

[0004] Currently, there are also some methods that use hardware pulse detection to detect phase loss in the power grid. It is necessary to add hardware to integrate and shape the three-phase power supply and output a stable level signal. When there is a phase loss, a pulse signal is output for CPU pin detection and judgment. This will increase hardware costs and wiring space. Summary of the invention

[0005] The present application provides a method and system for detecting phase loss in the three-phase input of a frequency converter. No additional hardware is required. By changing the software and the bus voltage acquisition detection algorithm, it is possible to detect whether a power phase loss state occurs, and whether the rectifier tube load is overloaded, thereby disconnecting the relay to protect the safety of the diode in the three-phase rectifier circuit.

[0006] In view of this, the present application provides a method for detecting phase loss of a three-phase input of a frequency converter, and the method is applied to a three-phase input phase loss detection system of a frequency converter, wherein the system comprises a three-phase rectifier circuit, in which three diodes D1, D2, and D3 constitute a three-phase half-wave rectifier with a common cathode, and three diodes D4, D5, and D6 constitute a three-phase half-wave rectifier with a common anode, and a switch J1 and a resistor R constitute a buffer relay. After rectification, the current charges capacitors C1 and C2 through closed switch J1 and inductor L, and capacitors C1 and C2 are connected in series to provide direct current to a rear-end load. After capacitors C1 and C2 are connected in series, the voltage across both ends of capacitors C1 and C2 is a bus voltage. The method comprises: when a three-phase power supply is connected, detecting the number of zero-crossing changes of the bus voltage ripple; if within a preset time, it is determined that the number of zero-crossing changes of the bus voltage ripple is less than a set number threshold, it is determined that the three-phase power supply is insufficient.

[0007] In combination with the first aspect, in a possible implementation, the method also includes: in a phase-missing state, detecting the bus voltage at preset time intervals, and determining the difference between the current voltage value of the bus voltage and the previous voltage value as the voltage difference value detaU of the bus voltage; if it is determined that the voltage difference value detaU of the bus voltage is greater than the set voltage difference value didU, it is determined that the rectifier diode is subjected to a large current shock.

[0008] In combination with the first aspect, in a possible implementation, the method further includes: timing the duration that the bus voltage difference value detaU is greater than the set voltage difference value didU, and if it is determined that the duration is greater than the set duration, determining that the diode in the three-phase rectifier circuit is overloaded.

[0009] In combination with the first aspect, in a possible implementation, the method further includes: when it is determined that the diode in the three-phase rectifier circuit is overloaded, disconnecting the switch J1 through the processing module to protect the diode in the three-phase rectifier circuit, and alarming and shutting down.

[0010] A second aspect of the present application provides a three-phase input phase loss detection system for a frequency converter, the system comprising a three-phase rectifier circuit, in which three diodes D1, D2, and D3 constitute a common cathode three-phase half-wave rectifier, three diodes D4, D5, and D6 constitute a common anode three-phase half-wave rectifier, a switch J1 and a resistor R constitute a buffer relay, and the rectified current passes through the closed switch J1 and the inductor L to charge the capacitor C1 and the capacitor C2, and the capacitor C1 and the capacitor C2 are connected in series to provide direct current to the rear-end load, and the voltage across the two ends of the capacitor C1 and the capacitor C2 is the bus voltage after being connected in series. The system also includes: a detection module, which is used to detect the number of zero-crossing changes of the bus voltage ripple when the three-phase power supply is connected; and a processing module, which is used to determine that the three-phase power supply is insufficient when the number of zero-crossing changes of the bus voltage ripple is less than a set number threshold within a preset time.

[0011] In combination with the second aspect, in a possible implementation method, the detection module is also used to detect the bus voltage at preset time intervals in a phase-missing state, and determine the difference between the current voltage value of the bus voltage and the previous voltage value as the voltage difference value detaU of the bus voltage; the processing module is also used to determine that when the voltage difference value detaU of the bus voltage is greater than the set voltage difference value didU, it is determined that the rectifier diode is subjected to a large current shock.

[0012] In combination with the second aspect, in a possible implementation method, the processing module is also used to time the duration that the bus voltage difference value detaU is greater than the set voltage difference value didU. If it is determined that the duration is greater than the set duration, it is determined that the diode in the three-phase rectifier circuit is overloaded.

[0013] In combination with the second aspect, in a possible implementation, the processing module is also used to disconnect the switch J1 through the processing module to protect the diode in the three-phase rectifier circuit and alarm and shut down when it is determined that the diode in the three-phase rectifier circuit is overloaded.

[0014] The present application provides a method and system for detecting phase loss of a three-phase input of a frequency converter. The method is applied to a three-phase input phase loss detection system of a frequency converter. The system includes a three-phase rectifier circuit. In the three-phase rectifier circuit, three diodes D1, D2, and D3 constitute a three-phase half-wave rectifier with a common cathode, and three diodes D4, D5, and D6 constitute a three-phase half-wave rectifier with a common anode. A switch J1 and a resistor R constitute a buffer relay. After rectification, the current passes through the closed switch J1 and the inductor L to charge the capacitor C1 and the capacitor C2. After the capacitor C1 and the capacitor C2 are connected in series, direct current is provided to the rear-end load. After the capacitor C1 and the capacitor C2 are connected in series, the voltage at both ends is the bus voltage. The method includes: when a three-phase power supply is connected, the number of zero-crossing changes of the bus voltage ripple is detected; if within a preset time, it is determined that the number of zero-crossing changes of the bus voltage ripple is less than a set number threshold, it is determined that the three-phase power supply is missing. In this way, the power supply phase loss state can be detected without adding additional hardware, which can save hardware cost and wiring space, and can determine the situation of three-phase power supply missing. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the structure of a three-phase input phase loss detection system for a frequency converter provided in an embodiment of the present application; Figure 2 A flowchart of a method for detecting a phase loss in a three-phase input of a frequency converter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0017] The term "and / or" in this application can be a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0018] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or modules is not necessarily limited to those steps or modules that are clearly listed, but may include other steps or modules that are not clearly listed or inherent to these processes, methods, products or devices.

[0019] With the development of power electronics technology, three-phase power grids are prone to phase loss in high-voltage and complex working environments. If the phase loss fault is not detected in time or the detection and elimination time is long, it will damage the subsequent related power equipment and cause serious economic and property losses. However, the traditional power grid phase loss fault mainly uses manual troubleshooting to detect the power grid phase loss fault, which is time-consuming and labor-intensive, and the detection is not timely. It is unable to respond quickly to changes in the power grid and there is a large delay problem.

[0020] Currently, there are also some methods that use hardware pulse detection to detect phase loss in the power grid. It is necessary to add hardware to integrate and shape the three-phase power supply and output a stable level signal. When there is a phase loss, a pulse signal is output for CPU pin detection and judgment. This will increase hardware costs and wiring space.

[0021] Therefore, this application provides a method for detecting phase loss in three-phase input of a frequency converter, which is applied to a three-phase input phase loss detection system of a frequency converter, see Figure 1 The system includes a three-phase rectifier circuit, in which three diodes D1, D2, and D3 form a common cathode three-phase half-wave rectifier, and three diodes D4, D5, and D6 form a common anode three-phase half-wave rectifier. Switch J1 and resistor R form a buffer relay. After rectification, the current passes through the closed switch J1 (wherein the resistor R plays a bypass buffer role) and the inductor L to charge the capacitor C1 and the capacitor C2. After the capacitor C1 and the capacitor C2 are connected in series, they provide direct current to the rear-end load. After the capacitor C1 and the capacitor C2 are connected in series, the voltage across the two ends is the bus voltage. Please refer to Figure 2 , the method comprising: S11. When connected to a three-phase power supply, detect the number of zero-point changes of the bus voltage ripple.

[0022] S12: If it is determined that the number of zero-crossing changes of the bus voltage ripple is less than the set number threshold within the preset time, it is determined that the three-phase power supply is insufficient.

[0023] Preferably, the set number threshold can be set to 3. The preset time can be set according to specific conditions, such as 20 milliseconds. It should be noted that in the case of phase loss, the ripple of the power grid charging the bus capacitor is increased, but the number of voltage ripple zero-crossing changes is reduced.

[0024] It can be understood that the method also includes: in a phase-missing state, detecting the bus voltage at preset time intervals, and determining the difference between the current voltage value of the bus voltage and the previous voltage value as the voltage difference value detaU of the bus voltage; if it is determined that the voltage difference value detaU of the bus voltage is greater than the set voltage difference value didU, it is determined that the rectifier diode is subjected to a large current shock.

[0025] It is understandable that the method further includes: timing the duration of the voltage difference value detaU of the bus voltage being greater than the set voltage difference value didU, and if it is determined that the duration is greater than the set duration, it is determined that the diode in the three-phase rectifier circuit is overloaded. The set duration can be set according to actual needs. When the set duration is longer, the diode can continue to work under certain impacts; when the set duration is shorter, the diode can react more sensitively to the impact of large currents.

[0026] It is understandable that the method further includes: when it is determined that the diode in the three-phase rectifier circuit is overloaded, the processing module disconnects the switch J1 to protect the diode in the three-phase rectifier circuit and issues an alarm to shut down.

[0027] The present application provides a method for detecting phase loss of a three-phase input of a frequency converter. The method is applied to a three-phase input phase loss detection system of a frequency converter. The system includes a three-phase rectifier circuit. In the three-phase rectifier circuit, three diodes D1, D2, and D3 constitute a three-phase half-wave rectifier with a common cathode, three diodes D4, D5, and D6 constitute a three-phase half-wave rectifier with a common anode, and a switch J1 and a resistor R constitute a buffer relay. After rectification, the current passes through the closed switch J1 and the inductor L to charge the capacitor C1 and the capacitor C2. After the capacitor C1 and the capacitor C2 are connected in series, direct current is provided to the rear-end load. After the capacitor C1 and the capacitor C2 are connected in series, the voltage at both ends is the bus voltage. The method includes: when a three-phase power supply is connected, the number of zero-crossing changes of the bus voltage ripple is detected; if within a preset time, it is determined that the number of zero-crossing changes of the bus voltage ripple is less than a set number threshold, it is determined that the three-phase power supply is missing. In this way, the power supply phase loss state can be detected without adding additional hardware, which can save hardware cost and wiring space, and can determine the situation of three-phase power supply missing.

[0028] See also Figure 1 The present application provides a frequency converter three-phase input phase loss detection system comprising: A three-phase rectifier circuit, in which three diodes D1, D2, and D3 constitute a common cathode three-phase half-wave rectifier, three diodes D4, D5, and D6 constitute a common anode three-phase half-wave rectifier, a switch J1 and a resistor R constitute a buffer relay, and the current after rectification charges the capacitor C1 and the capacitor C2 through the closed switch J1 and the inductor L. The capacitor C1 and the capacitor C2 are connected in series to provide direct current to the rear-end load, and the voltage across the two ends of the capacitor C1 and the capacitor C2 is the bus voltage after being connected in series. The system also includes: a detection module, which is used to detect the number of zero-crossing changes of the bus voltage ripple when the three-phase power supply is connected; a processing module, which is used to determine that the three-phase power supply is insufficient when the number of zero-crossing changes of the bus voltage ripple is less than the set number threshold within a preset time.

[0029] In a possible implementation, the detection module is also used to detect the bus voltage at preset time intervals in a phase-missing state, and determine the difference between the current voltage value and the previous voltage value of the bus voltage as the voltage difference value detaU of the bus voltage; the processing module is also used to determine that when the voltage difference value detaU of the bus voltage is greater than the set voltage difference value didU, it is determined that the rectifier diode is subjected to a large current shock.

[0030] In a possible implementation, the processing module is also used to time the duration that the bus voltage difference value detaU is greater than the set voltage difference value didU. If it is determined that the duration is greater than the set duration, it is determined that the diode in the three-phase rectifier circuit is overloaded.

[0031] In a possible implementation, the processing module is further configured to disconnect the switch J1 through the processing module to protect the diode in the three-phase rectifier circuit and to generate an alarm to shut down when it is determined that the diode in the three-phase rectifier circuit is overloaded.

[0032] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0033] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., various media that can store program codes.

[0034] In the embodiments provided in this application, it should be understood that the disclosed methods can be implemented in other ways without exceeding the spirit and scope of this application. The current embodiment is only an illustrative example and should not be used as a limitation. The specific content given should not limit the purpose of this application. For example, some features can be ignored or not executed.

[0035] The technical means disclosed in the present application are not limited to the technical means disclosed in the above-mentioned implementation methods, but also include technical solutions composed of any combination of the above technical features. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of this application, and these improvements and modifications are also regarded as the protection scope of this application.

[0036] The above is a detailed introduction to a method and system for detecting phase loss in a three-phase input of a frequency converter provided in an embodiment of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and its core idea of ​​the present application. At the same time, for a person skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for detecting phase loss of three-phase input of a frequency converter, characterized in that: The method is applied to a three-phase input phase loss detection system of a frequency converter. The system includes a three-phase rectifier circuit. In the three-phase rectifier circuit, three diodes D1, D2, and D3 constitute a common cathode three-phase half-wave rectifier, three diodes D4, D5, and D6 constitute a common anode three-phase half-wave rectifier, a switch J1 and a resistor R constitute a buffer relay, and the rectified current passes through the closed switch J1 and the inductor L to charge the capacitor C1 and the capacitor C2. The capacitor C1 and the capacitor C2 are connected in series to provide direct current to the rear-end load. The voltage across the capacitor C1 and the capacitor C2 is the bus voltage after being connected in series. The method includes: When connected to a three-phase power supply, detect the number of zero-crossing changes of the bus voltage ripple; If within the preset time, it is determined that the number of zero-crossing changes of the bus voltage ripple is less than the set number threshold, it is determined that the three-phase power supply is insufficient.

2. The inverter three-phase input missing phase detection method according to claim 1 is characterized in that: The method further comprises: In the phase-loss state, the bus voltage is detected at a preset time interval, and the difference between the current bus voltage value and the previous bus voltage value is determined as the bus voltage difference value detaU; If it is determined that the voltage difference value detaU of the bus voltage is greater than the set voltage difference value didU, it is determined that the rectifier diode is subjected to a large current shock.

3. The inverter three-phase input missing phase detection method according to claim 2 is characterized in that: The method further comprises: The duration during which the voltage difference value detaU of the bus voltage is greater than the set voltage difference value didU is timed, and if it is determined that the duration is greater than the set duration, it is determined that the diode in the three-phase rectifier circuit is overloaded.

4. The inverter three-phase input missing phase detection method according to claim 3 is characterized in that: The method further comprises: When it is determined that the diode in the three-phase rectifier circuit is overloaded, the switch J1 is disconnected by the processing module to protect the diode in the three-phase rectifier circuit, and an alarm is issued to shut down the circuit.

5. A three-phase input phase loss detection system for a frequency converter, characterized in that: The system comprises a three-phase rectifier circuit, in which three diodes D1, D2 and D3 constitute a common cathode three-phase half-wave rectifier, three diodes D4, D5 and D6 constitute a common anode three-phase half-wave rectifier, a switch J1 and a resistor R constitute a buffer relay, and the rectified current passes through the closed switch J1 and the inductor L to charge the capacitor C1 and the capacitor C2, and the capacitor C1 and the capacitor C2 are connected in series to provide direct current to the rear-end load, and the voltage across the two ends of the capacitor C1 and the capacitor C2 is the bus voltage, and the system also comprises: A detection module, used to detect the number of zero-crossing changes of bus voltage ripple when connected to a three-phase power supply; The processing module is used to determine that the three-phase power supply is insufficient when the number of zero-crossing changes of the bus voltage ripple is less than a set number threshold within a preset time.

6. The inverter three-phase input phase loss detection system according to claim 5, characterized in that: The detection module is further used to detect the bus voltage at a preset time interval in the phase loss state, and determine the difference between the current voltage value of the bus voltage and the previous voltage value as the voltage difference value detaU of the bus voltage; The processing module is further used to determine that when the voltage difference value detaU of the bus voltage is greater than the set voltage difference value didU, it is determined that the rectifier diode is subjected to a large current shock.

7. The inverter three-phase input phase loss detection system according to claim 6, characterized in that: The processing module is further used to time the duration that the voltage difference value detaU of the bus voltage is greater than the set voltage difference value didU. If it is determined that the duration is greater than the set duration, it is determined that the diode in the three-phase rectifier circuit is overloaded.

8. The inverter three-phase input phase loss detection system according to claim 7, characterized in that: The processing module is also used to disconnect the switch J1 through the processing module to protect the diode in the three-phase rectifier circuit and alarm and shut down when it is determined that the diode in the three-phase rectifier circuit is overloaded.

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