Magnetic ring overheat protection method, system, device, equipment and medium

Abstract

The present invention discloses a method, system, device, equipment, and medium for overheating protection of a magnetic ring in a parallel inverter system. The method is applied to a control unit in the magnetic ring overheating protection system, which also includes a current sampling unit, a controlled switch, a DC power supply, and a winding configured for the magnetic ring in the parallel inverter system. The method includes: receiving the power frequency circulating current of the parallel inverter system collected by the current sampling unit; when it is detected that the parallel inverter system meets a preset magnetic ring overheating protection trigger condition, controlling the controlled switch to close to connect the DC circuit between the DC power supply and the winding, wherein the current output by the DC power supply is such that the DC bias added to the magnetic ring by the winding is greater than or equal to the sum of the power frequency circulating current and the saturation current of the magnetic ring. The magnetic ring overheating protection scheme for the parallel inverter system provided by the present invention can avoid safety accidents caused by overheating of the magnetic ring due to the power frequency circulating current generated by the parallel inverter system.

Description

Technical Field

[0001] The present invention relates to the field of circuit control technology, and in particular to a method, system, device, equipment and medium for overheating protection of a magnetic ring of a parallel inverter system. Background Art

[0002] Currently, to address EMI (Electromagnetic Interference) issues, a magnetic ring is typically installed between the inverter's AC filter capacitor and the AC output to suppress common-mode noise. In a parallel inverter system, power-frequency circulating currents may be generated between the parallel inverters, potentially reaching tens of amperes (A). When there is no power-frequency circulating current, the total power-frequency current flowing through the magnetic ring is zero, allowing the magnetic ring to operate normally with virtually no heat generation. However, when power-frequency circulating currents are generated in the parallel inverter system, they flow entirely through the added magnetic ring, potentially causing a sharp increase in magnetic ring losses. In the most serious cases, localized overheating can cause the ring itself and nearby insulation materials to fail, leading to safety incidents. Summary of the Invention

[0003] The main purpose of the present invention is to provide a method, system, device, equipment and medium for overheating protection of the magnetic ring of the inverter parallel system, aiming to provide a magnetic ring overheating protection scheme for the inverter parallel system, so as to avoid safety accidents caused by overheating of the magnetic ring due to the power frequency circulating current generated by the inverter parallel system.

[0004] To achieve the above objectives, the present invention provides a method for overheating protection of a magnetic ring in a parallel inverter system. The method is applied to a control unit in the magnetic ring overheating protection system. The magnetic ring overheating protection system further includes a current sampling unit, a controlled switch, a DC power supply, and windings provided for the magnetic rings in the parallel inverter system. The method includes:

[0005] receiving the power frequency circulating current of the inverter parallel system collected by the current sampling unit;

[0006] When it is detected that the inverter parallel system meets the preset magnetic ring overheat protection trigger condition, the controlled switch is controlled to close to connect the DC circuit between the DC power supply and the winding, wherein the current output by the DC power supply is such that the DC bias added by the winding to the magnetic ring is greater than or equal to the sum of the power frequency circulating current and the saturation current of the magnetic ring.

[0007] Optionally, before the step of controlling the controlled switch to close, the method further includes:

[0008] When it is detected that the power frequency circulating current is greater than a first threshold, it is determined that the magnetic ring overheat protection triggering condition is met.

[0009] Optionally, after the step of receiving the power frequency circulating current of the parallel inverter system collected by the current sampling unit, the method further includes:

[0010] When it is detected that the power frequency circulating current is less than a second threshold, the controlled switch is controlled to turn on to disconnect the DC loop between the DC power supply and the winding, wherein the second threshold is less than the first threshold.

[0011] Optionally, the magnetic ring overheat protection system further includes a temperature acquisition unit, and before the step of controlling the controlled switch to close, further includes:

[0012] receiving the temperature value of the magnetic ring collected by the temperature collection unit;

[0013] When it is detected that the temperature value is greater than a third threshold, it is determined that the magnetic ring overheat protection triggering condition is met.

[0014] Optionally, after the step of receiving the power frequency circulating current of the parallel inverter system collected by the current sampling unit, the method further includes:

[0015] When it is detected that the inverter parallel system meets the magnetic ring overheat protection condition, the sum of the power frequency circulating current and the saturation current of the magnetic ring is calculated to obtain a target DC bias;

[0016] Calculating a target current value according to the target DC bias and the number of turns of the winding;

[0017] The DC power supply is controlled to output a DC current having the target current value.

[0018] Optionally, the magnetic ring overheat protection system further includes an early warning unit, and after the step of controlling the controlled switch to close, further includes:

[0019] Starting from closing the controlled switch, timing the duration of the inverter parallel system meeting the magnetic ring overheat protection condition;

[0020] When the timing duration is greater than the preset duration, the warning unit is controlled to output a warning prompt.

[0021] To achieve the above-mentioned object, the present invention further provides a magnetic ring overheat protection system for a parallel inverter system, comprising a current sampling unit, a control unit, a controlled switch, a DC power supply, and a winding provided for the magnetic ring in the parallel inverter system;

[0022] The current sampling unit is used to collect the power frequency circulating current of the inverter parallel system and output it to the control unit;

[0023] The controlled switch is controlled by the control unit and is used to connect or disconnect the DC circuit between the DC power supply and the winding;

[0024] The magnitude of the current output by the DC power supply is such that the DC bias added by the winding to the magnetic ring is greater than or equal to the sum of the power frequency circulating current and the saturation current of the magnetic ring;

[0025] The control unit is used to execute the magnetic ring overheat protection method of the inverter parallel system as described above.

[0026] Optionally, the controlled switch is provided outside the DC power supply and is used to cut off at least one connecting line between the DC power supply and the winding.

[0027] Optionally, the controlled switch is arranged inside the DC power supply, and an inductor is arranged on one of the connecting lines between the DC power supply and the winding, or an inductor is arranged on each of the two connecting lines, or a differential mode inductor is arranged on the two connecting lines.

[0028] To achieve the above objectives, the present invention further provides a magnetic ring overheating protection device for a parallel inverter system. The device is applied to a control unit in the magnetic ring overheating protection system. The magnetic ring overheating protection system further includes a current sampling unit, a controlled switch, a DC power supply, and a winding provided for the magnetic ring in the parallel inverter system. The device includes:

[0029] A receiving module, configured to receive the power frequency circulating current of the inverter parallel system collected by the current sampling unit;

[0030] The control module is configured to control the controlled switch to close when detecting that the inverter parallel system meets a preset magnetic ring overheat protection trigger condition, so as to connect the DC circuit between the DC power supply and the winding, wherein the current output by the DC power supply is such that the DC bias added by the winding to the magnetic ring is greater than or equal to the sum of the power frequency circulating current and the saturation current of the magnetic ring.

[0031] To achieve the above-mentioned objectives, the present invention also provides a magnetic ring overheating protection device, which includes: a memory, a processor, and a magnetic ring overheating protection program stored in the memory and runnable on the processor. When the magnetic ring overheating protection program is executed by the processor, the steps of the magnetic ring overheating protection method described above are implemented.

[0032] In addition, to achieve the above-mentioned purpose, the present invention also proposes a computer-readable storage medium, on which a magnetic ring overheating protection program is stored. When the magnetic ring overheating protection program is executed by a processor, the steps of the magnetic ring overheating protection method described above are implemented.

[0033] The present invention provides a magnetic ring overheat protection system for a parallel inverter system. The magnetic ring overheat protection system includes a control unit, a current sampling unit, a controlled switch, a DC power supply, and a winding configured for the magnetic ring in the parallel inverter system. The control unit receives the power frequency circulating current of the parallel inverter system collected by the current sampling unit. When it detects that the parallel inverter system meets the magnetic ring overheat protection triggering condition, the control unit controls the controlled switch to close to connect the DC circuit between the DC power supply and the winding. The DC power supply outputs a current whose magnitude causes the DC bias added to the magnetic ring by the winding to be greater than or equal to the sum of the power frequency circulating current and the saturation current of the magnetic ring. The present invention implements a magnetic ring overheat protection scheme for the parallel inverter system, avoiding safety accidents caused by magnetic ring overheating due to the power frequency circulating current generated by the parallel inverter system. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a flow chart of a first embodiment of a magnetic ring overheat protection method according to the present invention;

[0035] Figure 2 A schematic diagram of a magnetic ring overheat protection system according to an embodiment of the present invention;

[0036] Figure 3 A schematic diagram of a hysteresis loop of a magnetic ring involved in an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of the structure of the hardware operating environment involved in the embodiment of the present invention.

[0038] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0039] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0040] Example 1

[0041] An embodiment of the present invention provides a method for overheating protection of a magnetic ring in an inverter parallel system. The method is applied to a control unit in the magnetic ring overheating protection system. The magnetic ring overheating protection system further includes a current sampling unit, a controlled switch, a DC power supply, and a winding set for the magnetic ring in the inverter parallel system. Figure 1 , the method comprising:

[0042] Step S10, receiving the power frequency circulating current of the inverter parallel system collected by the current sampling unit;

[0043] In this embodiment, the inverter parallel system refers to a system with at least two inverters connected in parallel, with the DC (direct current) input side and AC (alternating current) output side of each inverter short-circuited, which may generate power frequency circulating current. To solve the EMI problem, a magnetic ring is usually installed between the AC filter capacitor and the AC output terminal of the inverter. That is, the AC line between the AC filter capacitor and the AC output terminal serves as the winding of the magnetic ring to suppress common-mode noise. When power frequency circulating current is generated, the power frequency circulating current flows entirely through the added magnetic ring, which will lead to increased magnetic ring loss. When the power frequency circulating current is large, it may cause the magnetic ring to overheat, causing the magnetic ring itself and nearby insulation materials to fail, leading to safety accidents.

[0044] In order to solve the above problem, in this embodiment, a magnetic ring overheat protection system is provided, which includes a control unit, a controlled switch, a DC power supply and a winding provided for the magnetic ring. This winding is a new winding relative to the original winding of the magnetic ring. The winding described in the following embodiments refers to this new winding. Figure 2 , shows a schematic diagram of a magnetic ring overheating protection system, but the magnetic ring overheating protection system of each embodiment of the present invention is not limited to that shown in the figure. Figure 2 The detection control unit is the control unit, the current limiting source is the DC power supply, and the winding A is the winding.

[0045] The current sampling unit can be used to collect the power frequency circulating current and send the collected power frequency circulating current to the control unit. The current sampling unit can be implemented using a Hall effect device or a similar device, which is not limited in this embodiment. The current sampling unit can be set between the AC filter capacitor and the AC output terminal of the inverter. The positional relationship between the current sampling unit and the magnetic ring is not limited. The magnetic ring can be located between the current sampling unit and the AC output terminal, or between the magnetic ring and the AC output terminal.

[0046] A connecting line is provided between the DC power supply and the winding. The DC circuit between the DC power supply and the winding can be opened or closed by controlling the opening and closing of a controlled switch. When the DC circuit between the DC power supply and the winding is connected, the DC current output by the DC power supply flows through the winding, thereby adding a DC bias to the magnetic ring. The DC bias is equal to the DC current output multiplied by the number of turns of the winding. The controlled switch is initially set to the open state, which means that the DC circuit between the DC power supply and the winding is initially disconnected, ensuring that the magnetic ring can properly perform its common-mode noise suppression function.

[0047] The control unit is connected to the controlled switch and is used to control the opening and closing of the controlled switch.

[0048] The control unit can receive the power frequency circulating current collected by the current sampling unit. In a specific embodiment, the current sampling unit can collect the power frequency circulating current in real time and output the collected power frequency circulating current to the control unit in real time. The control unit controls the opening and closing of the controlled switch in real time based on the power frequency circulating current. Alternatively, the current sampling unit can collect the power frequency circulating current at regular time intervals. The time interval can be controlled within a certain range as needed to reduce the power consumption of the magnetic ring overheating protection system while ensuring that a sudden increase in the power frequency circulating current does not cause the magnetic ring to overheat and cause a safety accident within the time interval.

[0049] The control unit can detect whether the inverter parallel system meets the magnetic ring overheat protection triggering conditions. The magnetic ring overheat protection triggering conditions can be pre-set as needed. For example, it can be set to when the power frequency circulating current in the inverter parallel system exceeds a certain threshold, or when the temperature of the magnetic ring in the inverter parallel system exceeds a certain threshold.

[0050] Furthermore, in one embodiment, after receiving the power frequency circulating current output by the current sampling unit, the control unit can detect whether the power frequency circulating current is greater than a first threshold. The first threshold can be set as needed so that when the power frequency circulating current is below the first threshold, the magnetic ring can operate normally and the temperature rise is within specifications, eliminating the need for additional heat dissipation measures. The specific value is set based on actual conditions. When it is detected that the power frequency circulating current is greater than the first threshold, the control unit determines that the current inverter parallel system meets the magnetic ring overheat protection triggering condition.

[0051] Step S20: When it is detected that the trigger condition for the overheat protection of the magnetic ring is met, the controlled switch is controlled to close to connect the DC circuit between the DC power supply and the winding, wherein the current output by the DC power supply is such that the DC bias added by the winding to the magnetic ring is greater than or equal to the sum of the power frequency circulating current and the saturation current of the magnetic ring.

[0052] When the control unit determines that the inverter parallel system meets the triggering conditions for magnetic ring overheat protection, the control unit can control the controlled switch to close to connect the DC circuit between the DC power supply and the winding, so that the DC current output by the DC power supply flows through the winding, adding a DC bias to the magnetic ring. The current output by the DC power supply is large enough to make the DC bias added by the winding to the magnetic ring greater than or equal to the sum of the power frequency circulating current and the saturation current of the magnetic ring. The saturation current refers to the minimum current value that causes the magnetic ring to reach a saturated state. There are many ways to achieve this purpose, which are not limited in this embodiment. For example, in one embodiment, the DC power supply can use a constant current source, and the current output by the constant current source can be a fixed value set in advance according to needs. This fixed value can be determined based on the maximum power frequency circulating current of the inverter parallel system, the saturation current of the magnetic ring, and the number of turns of the winding. Assuming that the maximum power frequency circulating current of the inverter parallel system is 30A (effective value) and the saturation current of the magnetic ring is 20A, the DC bias should reach 20+30*1.414≈62A. The current output by the DC power supply is then calculated based on the DC bias and the number of turns of the winding. For example, when the number of turns is 1, the current output by the DC power supply is 62A. For another example, in another embodiment, the DC power supply can use an adjustable constant current source, and the control unit can calculate the current output by the DC power supply based on the power frequency circulating current and the saturation current of the magnetic ring received from the current sampling unit, as well as the number of turns of the winding.

[0053] It should be noted that when the inverter parallel system meets the triggering conditions for magnetic ring overheating protection, by connecting the DC circuit between the DC power supply and the winding, the current output by the DC power supply is large enough to make the DC bias added by the winding to the magnetic ring greater than or equal to the sum of the power frequency circulating current and the saturation current of the magnetic ring. The purpose is to make the magnetic ring quickly reach a saturation state after deducting the power frequency circulating current from the DC bias of the magnetic ring. In this state, the relative magnetic permeability of the magnetic ring drops to 1, which is equivalent to a vacuum state, so that the superimposed power frequency circulating current cannot cause the magnetic ring to generate losses, completely solving the heating and safety problems caused by excessive magnetic ring losses.

[0054] The following combination Figure 3 The schematic diagram of the hysteresis loop of a soft magnetic material shown in Figure 2 illustrates the principle. When an AC current is applied to a magnetic ring, the ring's losses (primarily considering hysteresis losses) are equal to the area encompassed by the hysteresis loop multiplied by the ring's volume multiplied by the current frequency. The smaller the applied AC current (corresponding to a smaller value of the horizontal coordinate H), the smaller the closed loop formed by the hysteresis loop and the lower the losses. When the applied current causes the magnetic field to reach H3, the losses reach a maximum, and further increases in current will only increase the losses to a limited extent. If a large DC current is superimposed on the AC current, causing the initial state to far exceed H3, the area encompassed by the hysteresis loop becomes very small, resulting in almost no losses.

[0055] Furthermore, if the trigger condition for magnetic ring overheat protection is set to be that the power frequency circulating current is greater than a first threshold, then when the power frequency circulating current is less than or equal to the first threshold, in a specific embodiment, the operation performed by the control unit can be configured as needed and is not limited in this embodiment. For example, in one embodiment, when the power frequency circulating current is less than or equal to the first threshold, if the controlled switch is in the open state, the control unit may perform no processing and maintain the controlled switch in the open state, thereby ensuring the normal common-mode noise suppression function of the magnetic ring; when the power frequency circulating current is less than or equal to the first threshold, if the controlled switch is in the closed state, the control unit may control the controlled switch to open, thereby ensuring the normal common-mode noise suppression function of the magnetic ring.

[0056] In this embodiment, a magnetic ring overheat protection system for a parallel inverter system is provided. The magnetic ring overheat protection system includes a control unit, a current sampling unit, a controlled switch, a DC power supply, and a winding configured for the magnetic ring in the parallel inverter system. The control unit receives the power frequency circulating current of the parallel inverter system collected by the current sampling unit. When it is detected that the parallel inverter system meets a preset magnetic ring overheat protection trigger condition, the control unit controls the controlled switch to close to connect the DC circuit between the DC power supply and the winding. The current output by the DC power supply is such that the DC bias added to the magnetic ring by the winding is greater than or equal to the sum of the power frequency circulating current and the saturation current of the magnetic ring. This embodiment implements a magnetic ring overheat protection scheme for the parallel inverter system, avoiding safety accidents caused by magnetic ring overheating due to the power frequency circulating current generated by the parallel inverter system.

[0057] Moreover, compared with the solution of cooling the magnetic ring by adding an electric fan, the magnetic ring overheating protection system involved in the magnetic ring overheating protection solution in this embodiment has a simple structure and a small size, will not bring about major structural design changes to the inverter parallel system, and is more convenient to deploy and implement.

[0058] Furthermore, in one embodiment, after step S10, the following steps are further included:

[0059] Step S30, when it is detected that the inverter parallel system meets the magnetic ring overheat protection condition, calculating the sum of the power frequency circulating current and the saturation current of the magnetic ring to obtain a target DC bias;

[0060] When the parallel inverter system meets the magnetic ring overheat protection conditions, the control unit can also calculate the sum of the power frequency circulating current and the magnetic ring's saturation current. The resulting result is hereinafter referred to as the target DC bias for clarity. It is understood that when the magnetic ring's DC bias is greater than or equal to the target DC bias, the magnetic ring is definitely in a saturated state.

[0061] Step S40, calculating a target current value according to the target DC bias and the number of turns of the winding;

[0062] The control unit can calculate a current value capable of generating the target DC bias based on the target DC bias and the number of turns of the winding, that is, based on the relationship between the DC bias and the number of turns of the winding. The target current value can be equal to or greater than the target current value as needed. The current value capable of generating the target DC bias can be obtained by dividing the target DC bias by the number of turns of the winding.

[0063] Step S50: Control the DC power supply to output a DC current of the target current value.

[0064] In this embodiment, by calculating the target current value that meets the requirements based on the collected power frequency circulating current, and controlling the DC power supply to output a DC current of the target current value, on the one hand, the magnetic ring overheat protection system can achieve the overheat protection effect with minimal power consumption; on the other hand, the magnetic ring overheat protection system can be applied to various inverter parallel systems without the need to set different magnetic ring overheat protection systems for different inverter parallel systems.

[0065] Furthermore, in one embodiment, when the magnetic ring overheat protection triggering condition is that the power frequency circulating current is greater than the first threshold, after step S10, the following further steps are included:

[0066] Step S60: When it is detected that the power frequency circulating current is less than a second threshold, the controlled switch is controlled to turn on to disconnect the DC circuit between the DC power supply and the winding, wherein the second threshold is less than the first threshold.

[0067] After receiving the power frequency circulating current output by the current sampling unit, the control unit can also detect whether the power frequency circulating current is less than a second threshold. This second threshold is less than the first threshold, for example, by 5A. The specific value can be set as needed. The purpose of setting the second threshold less than the first threshold is to prevent repeated operation of the controlled switch. When the control unit detects that the power frequency circulating current is less than the second threshold, it controls the controlled switch to open, disconnecting the DC circuit between the DC power supply and the winding, thereby ensuring the normal common-mode noise suppression function of the magnetic ring.

[0068] It can be understood that when the controlled switch is in the open state, if the power frequency circulating current is greater than the first threshold value, the controlled switch is controlled to close to avoid safety accidents caused by overheating of the magnetic ring; if the power frequency circulating current is less than or equal to the first threshold value, the controlled switch is continuously in the open state to ensure the normal common-mode noise suppression function of the magnetic ring; when the controlled switch is in the closed state, if the power frequency circulating current is less than the second threshold value, the controlled switch is controlled to open to ensure the normal common-mode noise suppression function of the magnetic ring; if the power frequency circulating current is greater than or equal to the second threshold value, the controlled switch is continuously in the closed state to avoid safety accidents caused by overheating of the magnetic ring.

[0069] Example 2

[0070] Based on the above-described first embodiment, the step of controlling the controlled switch to close in step S20 in the above-described embodiment may further include steps A10 and A20. The magnetic ring overheat protection system may further include a temperature acquisition unit, which is described below. In this embodiment, the same or similar contents as those in the above-described first and second embodiments may be referred to above and will not be further described.

[0071] Step A10, receiving the temperature value of the magnetic ring collected by the temperature collection unit;

[0072] In this embodiment, the magnetic ring overheat protection triggering condition may be that the temperature of the magnetic ring is greater than a certain threshold. A temperature acquisition unit is also provided in the magnetic ring overheat protection system for acquiring the temperature of the magnetic ring.

[0073] The specific implementation of the temperature acquisition unit is not limited in this embodiment, and for example, a conventional temperature sensor can be used. The temperature acquisition unit can be arranged near the magnetic ring to facilitate the acquisition of accurate magnetic ring temperature values.

[0074] The temperature acquisition unit outputs the acquired temperature value to the control unit. Similar to the current acquisition unit, the temperature acquisition unit can also acquire temperature values ​​in real time or at certain time intervals.

[0075] Step A20: When it is detected that the temperature value is greater than a third threshold, it is determined that the magnetic ring overheat protection triggering condition is met.

[0076] The third threshold can be set as needed and is not limited here. When the temperature of the magnetic ring is greater than the third threshold, it indicates that the temperature of the magnetic ring is high, and continued temperature increase may cause a safety accident. When the temperature is greater than the third threshold, the control unit determines that the trigger condition for magnetic ring overheat protection is met, that is, it controls the controlled switch to close to perform overheat protection to avoid safety accidents caused by magnetic ring overheating.

[0077] Furthermore, in one embodiment, when the temperature value is detected to be less than or equal to the third threshold, if the controlled switch is in the open state, the control unit may not perform any processing and maintain the open state. Alternatively, the control unit may further detect whether the power frequency circulating current is greater than the first threshold, and if so, control the controlled switch to close. When the temperature value is detected to be less than or equal to the third threshold, if the controlled switch is in the closed state, the control unit may directly control the controlled switch to open. Alternatively, when the temperature value is detected to be less than or equal to the third threshold, if the controlled switch is in the closed state, the control unit may further detect whether the temperature value is less than a fourth threshold (the fourth threshold is less than the third threshold), and if the temperature value is less than the fourth threshold, control the controlled switch to open. If the temperature value is greater than or equal to the fourth threshold, control the controlled switch to remain closed to prevent repeated operation of the controlled switch. Alternatively, when the temperature value is detected to be less than or equal to the third threshold, if the controlled switch is in the closed state, the control unit may further detect whether the power frequency circulating current is less than or equal to the first threshold, and if so, control the controlled switch to open. If so, control the controlled switch to remain closed.

[0078] Furthermore, in one embodiment, after step S20, the following steps are further included:

[0079] Step A30, starting from closing the controlled switch, counting the duration of the inverter parallel system meeting the magnetic ring overheat protection condition;

[0080] In this embodiment, the magnetic ring overheat protection system may further include an early warning unit. The early warning unit is configured to output a controlled early warning prompt. The specific implementation of the early warning unit is not limited herein and may be implemented, for example, using a speaker, a vibration device, an indicator light, or the like.

[0081] After closing the controlled switch, the control unit may start timing the duration of the time during which the inverter parallel system meets the magnetic ring overheat protection condition.

[0082] Step A40: When the timing duration is greater than the preset duration, the warning unit is controlled to output a warning prompt.

[0083] The control unit can detect whether the timing duration is greater than a preset duration. The preset duration can be set as needed. When the timing duration is greater than the preset duration, it indicates that the state of large power frequency circulating current or high magnetic ring temperature has continued for a long time. Since the magnetic ring may lose its function of suppressing common mode noise when overheat protection is performed, in this embodiment, when the timing duration is greater than the preset duration, the control unit controls the early warning unit to output an early warning prompt so that managers of the inverter parallel system can check and troubleshoot EMI problems in a timely manner.

[0084] Furthermore, when the trigger condition for magnetic ring overheat protection is set to a power frequency circulating current greater than a first threshold, if the control unit detects that the power frequency circulating current is less than or equal to the first threshold before the timing duration reaches a preset duration, the control unit may restart the timing when the power frequency circulating current is again detected to be greater than the first threshold while the controlled switch is closed. Furthermore, in one embodiment, when the control unit opens the controlled switch only after detecting that the power frequency circulating current is less than a second threshold, the control unit may time the duration of the power frequency circulating current being greater than or equal to the second threshold starting from the time the controlled switch is closed, detect whether the timed duration is greater than the preset duration, and control the warning unit to output a warning prompt if the timed duration is greater than the preset duration.

[0085] Example 3

[0086] Based on the above-mentioned embodiment 1 and / or embodiment 2, this embodiment further provides a magnetic ring overheating protection system for a parallel inverter system, comprising a current sampling unit, a control unit, a controlled switch, a DC power supply, and a winding provided for the magnetic ring in the parallel inverter system;

[0087] The current sampling unit is used to collect the power frequency circulating current of the inverter parallel system and output it to the control unit;

[0088] The controlled switch is controlled by the control unit and is used to connect or disconnect the DC circuit between the DC power supply and the winding;

[0089] The magnitude of the current output by the DC power supply is such that the DC bias added by the winding to the magnetic ring is greater than or equal to the sum of the power frequency circulating current and the saturation current of the magnetic ring;

[0090] The control unit is used to execute the magnetic ring overheat protection method of the inverter parallel system in the above-mentioned embodiment 1 and / or embodiment 2.

[0091] The specific implementation of the magnetic ring overheating protection system of this embodiment can refer to the specific implementation of the magnetic ring overheating protection method in the above embodiment. The same or similar contents as those in the above embodiments 1 and 2 can be referred to the above introduction and will not be repeated hereafter.

[0092] Furthermore, in one embodiment, the controlled switch is provided outside the DC power supply and is used to cut off at least one connection line between the DC power supply and the winding. It should be noted that when the controlled switch is in the on state, the DC power supply and the winding are in a DC open circuit, and at the same time, a high impedance state should be ensured in the EMI frequency band (in actual application, the condition can be relaxed as long as the impedance in the low frequency band of CE (Conducted Emission), such as below 5MHz, is at least 3 times the impedance of the magnetic ring). If the winding has n turns, its impedance should be divided by n. 2When the controlled switch is set outside the DC power supply, it is located between the differential mode capacitor and the winding inside the DC power supply. The controlled switch can be regarded as a high resistance device, which can ensure that the impedance is divided by n 2 After the controlled switch is turned on, the high resistance remains, thereby ensuring that the magnetic ring can properly provide common-mode noise suppression when the controlled switch is in the on state. In another embodiment, when the controlled switch is located inside the DC power supply, that is, between the differential-mode capacitor and the winding inside the DC power supply, a high-resistance device can be provided between the differential-mode capacitor and the winding to ensure that the magnetic ring can properly provide common-mode noise suppression when the controlled switch is in the on state. For example, in one embodiment, an inductor can be provided on one of the connecting wires between the DC power supply and the winding, an inductor can be provided on each of the two connecting wires, or a differential-mode inductor can be provided on both connecting wires.

[0093] Example 4

[0094] Corresponding to the above-mentioned first, second, and third embodiments, an embodiment of the present invention further provides a magnetic ring overheating protection device for a parallel inverter system, characterized in that the device is applied to a control unit in the magnetic ring overheating protection system, the magnetic ring overheating protection system further comprising a current sampling unit, a controlled switch, a DC power supply, and a winding provided for the magnetic ring in the parallel inverter system, the device comprising:

[0095] A receiving module, configured to receive the power frequency circulating current of the inverter parallel system collected by the current sampling unit;

[0096] The control module is configured to control the controlled switch to close when detecting that the inverter parallel system meets a preset magnetic ring overheat protection trigger condition, so as to connect the DC circuit between the DC power supply and the winding, wherein the current output by the DC power supply is such that the DC bias added by the winding to the magnetic ring is greater than or equal to the sum of the power frequency circulating current and the saturation current of the magnetic ring.

[0097] Furthermore, the device further comprises:

[0098] The first determination module is configured to determine that a triggering condition for magnetic ring overheat protection is satisfied when it is detected that the power frequency circulating current is greater than a first threshold.

[0099] Furthermore, the control module is further configured to:

[0100] When it is detected that the power frequency circulating current is less than a second threshold, the controlled switch is controlled to turn on to disconnect the DC loop between the DC power supply and the winding, wherein the second threshold is less than the first threshold.

[0101] Furthermore, the magnetic ring overheat protection system further includes a temperature acquisition unit, and the receiving module is further used to: receive the temperature value of the magnetic ring acquired by the temperature acquisition unit;

[0102] The device further comprises:

[0103] The second determining module is configured to determine that the magnetic ring overheat protection triggering condition is satisfied when it is detected that the temperature value is greater than a third threshold.

[0104] Furthermore, the device further comprises:

[0105] a calculation module, configured to calculate the sum of the power frequency circulating current and the saturation current of the magnetic ring to obtain a target DC bias when it is detected that the inverter parallel system meets the magnetic ring overheat protection condition; and calculate a target current value based on the target DC bias and the number of turns of the winding;

[0106] The control module is further configured to control the DC power supply to output a DC current having the target current value.

[0107] Furthermore, the magnetic ring overheat protection system further includes an early warning unit, and the device further includes:

[0108] a timing module, configured to time the duration of the inverter parallel system meeting the magnetic ring overheat protection condition starting from closing the controlled switch;

[0109] The control module is further configured to control the warning unit to output a warning prompt when the timing duration is greater than a preset duration.

[0110] Example 5

[0111] Corresponding to the above-mentioned first, second, third and fourth embodiments, an embodiment of the present invention further provides a magnetic ring overheating protection device for a parallel inverter system.

[0112] like Figure 4 As shown, Figure 4 It is a schematic diagram of the device structure of the hardware operating environment involved in the embodiment of the present invention.

[0113] It should be noted that the magnetic ring overheating protection device in the embodiment of the present invention may be the control unit in the magnetic ring overheating protection system as described above.

[0114] like Figure 4As shown, the magnetic ring overheat protection device may include: a processor 1001, such as a CPU, a network interface 1004, a user interface 1003, a memory 1005, and a communication bus 1002. The communication bus 1002 is used to realize the connection and communication between these components. The user interface 1003 may include a display screen (Display), an input unit such as a keyboard (Keyboard), and the user interface 1003 may also include a standard wired interface and a wireless interface. The network interface 1004 may optionally include a standard wired interface and a wireless interface (such as a WI-FI interface). The memory 1005 may be a high-speed RAM memory or a stable memory (non-volatile memory), such as a disk memory. The memory 1005 may also be a storage device independent of the aforementioned processor 1001.

[0115] Those skilled in the art will understand that Figure 4 The device structure shown in the figure does not constitute a limitation on the magnetic ring overheat protection device, and may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0116] like Figure 4 As shown, the memory 1005 as a computer storage medium may include an operating system, a network communication module, a user interface module, and a magnetic ring overheat protection program. The operating system is a program that manages and controls the hardware and software resources of the device and supports the operation of the magnetic ring overheat protection program and other software or programs. Figure 4 In the device shown, the user interface 1003 is mainly used to communicate data with the client; the network interface 1004 is mainly used to establish a communication connection with the server; and the processor 1001 can be used to call the magnetic ring overheat protection program stored in the memory 1005 and perform the following operations:

[0117] receiving the power frequency circulating current of the inverter parallel system collected by the current sampling unit;

[0118] When it is detected that the inverter parallel system meets the preset magnetic ring overheat protection trigger condition, the controlled switch is controlled to close to connect the DC circuit between the DC power supply and the winding, wherein the current output by the DC power supply is such that the DC bias added by the winding to the magnetic ring is greater than or equal to the sum of the power frequency circulating current and the saturation current of the magnetic ring.

[0119] Furthermore, before the operation of controlling the controlled switch to close, the processor 1001 may also be configured to call a magnetic ring overheat protection program stored in the memory 1005 and perform the following operations:

[0120] When it is detected that the power frequency circulating current is greater than a first threshold, it is determined that the magnetic ring overheat protection triggering condition is met.

[0121] Furthermore, after receiving the power frequency circulating current of the inverter parallel system collected by the current sampling unit, the processor 1001 may also be configured to call a magnetic ring overheat protection program stored in the memory 1005 and perform the following operations:

[0122] When it is detected that the power frequency circulating current is less than a second threshold, the controlled switch is controlled to turn on to disconnect the DC loop between the DC power supply and the winding, wherein the second threshold is less than the first threshold.

[0123] Furthermore, the magnetic ring overheat protection system further includes a temperature acquisition unit. Before controlling the controlled switch to close, the processor 1001 may also be configured to call a magnetic ring overheat protection program stored in the memory 1005 and perform the following operations:

[0124] receiving the temperature value of the magnetic ring collected by the temperature collection unit;

[0125] When it is detected that the temperature value is greater than a third threshold, it is determined that the magnetic ring overheat protection triggering condition is met.

[0126] Furthermore, after receiving the power frequency circulating current of the inverter parallel system collected by the current sampling unit, the processor 1001 may also be configured to call a magnetic ring overheat protection program stored in the memory 1005 and perform the following operations:

[0127] When it is detected that the inverter parallel system meets the magnetic ring overheat protection condition, the sum of the power frequency circulating current and the saturation current of the magnetic ring is calculated to obtain a target DC bias;

[0128] Calculating a target current value according to the target DC bias and the number of turns of the winding;

[0129] The DC power supply is controlled to output a DC current having the target current value.

[0130] Furthermore, the magnetic ring overheat protection system further includes an early warning unit. After the operation of controlling the controlled switch to close, the processor 1001 may also be configured to call a magnetic ring overheat protection program stored in the memory 1005 and perform the following operations:

[0131] Starting from closing the controlled switch, timing the duration of the state in which the power frequency circulating current is greater than the first threshold;

[0132] When the timing duration is greater than the preset duration, the warning unit is controlled to output a warning prompt.

[0133] Example 6

[0134] Corresponding to the above-mentioned embodiments one, two, three, four and five, an embodiment of the present invention further proposes a computer-readable storage medium, on which a magnetic ring overheating protection program is stored. When the magnetic ring overheating protection program is executed by a processor, the steps of the magnetic ring overheating protection method described above are implemented.

[0135] The various embodiments of the magnetic ring overheating protection device, the magnetic ring overheating protection equipment and the computer-readable storage medium of the present invention can all refer to the various embodiments of the magnetic ring overheating protection method of the present invention, and will not be repeated here.

[0136] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0137] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0138] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, and of course can also be implemented by hardware, but in many cases the former is a better embodiment. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a number of instructions for enabling a terminal device (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in each embodiment of the present invention.

[0139] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A magnetic ring overheat protection method for a parallel inverter system, characterized in that: The method is applied to a control unit in a magnetic ring overheating protection system, wherein the magnetic ring overheating protection system further includes a current sampling unit, a controlled switch, a DC power supply, and windings provided for the magnetic rings in the inverter parallel system. The method includes: receiving the power frequency circulating current of the inverter parallel system collected by the current sampling unit; When it is detected that the inverter parallel system meets the preset magnetic ring overheat protection trigger condition, the controlled switch is controlled to close to connect the DC circuit between the DC power supply and the winding, wherein the current output by the DC power supply is such that the DC bias added by the winding to the magnetic ring is greater than or equal to the sum of the power frequency circulating current and the saturation current of the magnetic ring.

2. The magnetic ring overheat protection method for the inverter parallel system according to claim 1, characterized in that: Before the step of controlling the controlled switch to close, the method further includes: When it is detected that the power frequency circulating current is greater than a first threshold, it is determined that the magnetic ring overheat protection triggering condition is met.

3. The magnetic ring overheat protection method for the inverter parallel system according to claim 2, characterized in that: After the step of receiving the power frequency circulating current of the inverter parallel system collected by the current sampling unit, the method further includes: When it is detected that the power frequency circulating current is less than a second threshold, the controlled switch is controlled to turn on to disconnect the DC circuit between the DC power supply and the winding, wherein the second threshold is less than the first threshold.

4. The method for protecting the magnetic ring from overheating of the inverter parallel system according to claim 1, wherein: The magnetic ring overheat protection system further includes a temperature acquisition unit, and before the step of controlling the controlled switch to close, further includes: receiving the temperature value of the magnetic ring collected by the temperature collection unit; When it is detected that the temperature value is greater than a third threshold, it is determined that the magnetic ring overheat protection triggering condition is met.

5. The magnetic ring overheat protection method for the inverter parallel system according to claim 1, characterized in that: After the step of receiving the power frequency circulating current of the inverter parallel system collected by the current sampling unit, the method further includes: When it is detected that the inverter parallel system meets the magnetic ring overheat protection triggering condition, the sum of the power frequency circulating current and the saturation current of the magnetic ring is calculated to obtain a target DC bias; Calculating a target current value according to the target DC bias and the number of turns of the winding; The DC power supply is controlled to output a DC current having the target current value.

6. The magnetic ring overheat protection method for a parallel inverter system according to any one of claims 1 to 5, characterized in that: The magnetic ring overheat protection system further includes an early warning unit, and after the step of controlling the controlled switch to close, further includes: Starting from closing the controlled switch, timing the duration of the inverter parallel system meeting the magnetic ring overheat protection triggering condition; When the timing duration is greater than the preset duration, the warning unit is controlled to output a warning prompt.

7. A magnetic ring overheat protection system for an inverter parallel system, characterized in that: It includes a current sampling unit, a control unit, a controlled switch, a DC power supply, and a winding arranged for the magnetic ring in the inverter parallel system; The current sampling unit is used to collect the power frequency circulating current of the inverter parallel system and output it to the control unit; The controlled switch is controlled by the control unit and is used to connect or disconnect the DC circuit between the DC power supply and the winding; The magnitude of the current output by the DC power supply is such that the DC bias added by the winding to the magnetic ring is greater than or equal to the sum of the power frequency circulating current and the saturation current of the magnetic ring; The control unit is used to execute the magnetic ring overheat protection method for the inverter parallel system according to any one of claims 1 to 6.

8. The magnetic ring overheat protection system for the inverter parallel system according to claim 7, characterized in that: The controlled switch is arranged outside the DC power supply and is used to cut off at least one connecting line between the DC power supply and the winding.

9. The magnetic ring overheat protection system for the inverter parallel system according to claim 7, characterized in that: The controlled switch is arranged inside the DC power supply, and an inductor is arranged on one of the connecting lines between the DC power supply and the winding, or an inductor is arranged on each of the two connecting lines, or a differential mode inductor is arranged on the two connecting lines.

10. A magnetic ring overheat protection device for an inverter parallel system, characterized in that: The device is applied to a control unit in a magnetic ring overheating protection system. The magnetic ring overheating protection system further includes a current sampling unit, a controlled switch, a DC power supply, and a winding provided for the magnetic ring in the inverter parallel system. The device includes: A receiving module, configured to receive the power frequency circulating current of the inverter parallel system collected by the current sampling unit; A control module is configured to control the controlled switch to close when it is detected that the inverter parallel system meets a preset magnetic ring overheat protection trigger condition, so as to connect the DC circuit between the DC power supply and the winding, wherein the current output by the DC power supply is such that the DC bias added by the winding to the magnetic ring is greater than or equal to the sum of the power frequency circulating current and the saturation current of the magnetic ring.

11. A magnetic ring overheat protection device for an inverter parallel system, characterized in that: The magnetic ring overheating protection device includes: a memory, a processor, and a magnetic ring overheating protection program stored in the memory and executable on the processor. When the magnetic ring overheating protection program is executed by the processor, the steps of the magnetic ring overheating protection method according to any one of claims 1 to 6 are implemented.

12. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a magnetic ring overheat protection program, which, when executed by a processor, implements the steps of the magnetic ring overheat protection method according to any one of claims 1 to 6.

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