Firefighting water supply system and method based on double squirrel cage motor

Abstract

The application discloses a fire-fighting water supply system and method based on a double squirrel cage motor, wherein the system comprises a double squirrel cage motor, a centrifugal pump and a water use control module; the output end of the double squirrel cage motor is connected with the centrifugal pump, the double squirrel cage motor controls fire-fighting water supply data of the centrifugal pump based on relevant parameters provided by the water use control module; the double squirrel cage motor is used for guaranteeing starting torque and limiting starting current of the fire-fighting pump full load through an outer squirrel cage of a rotor; the double squirrel cage motor enables the centrifugal pump to operate in a high-efficiency area at a rated operating point through an inner squirrel cage of the rotor, and when the centrifugal pump operates at an over-flow, the double squirrel cage motor limits torque of the motor through maximum torque Tm2 of the inner squirrel cage to rapidly drop the rotating speed of the fire-fighting pump set, thereby effectively preventing the centrifugal pump from overloading.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fire pump, in particular to a fire water supply system and method based on double squirrel cage motor. BACKGROUND

[0002] Fire pump requires no failure to stop the pump during fire operation, and must consider automatic input without operation. However, the inlet and outlet valves of the water pump are in full open state in principle, and the water consumption of the terminal fire equipment (such as fire hydrant) is often difficult to effectively constrain. In addition, the first started pump group of the multi-pump parallel water supply system is most likely to bear the entire load in a short time, but the pump group for fire fighting is not allowed to overload and stop or cavitate (if the first pump group is overloaded and stopped, the subsequent water consumption is larger and more likely to cause another standby unit to overload or cavitate, resulting in system collapse) to cause the water supply system to collapse.

[0003] If a conventional double squirrel cage motor or high slip motor is used to drive the fire pump in the prior art, the following problems still exist:

[0004] A. The design of ordinary double squirrel cage motor: the conductor section of the rotor outer cage (upper cage) is small, only responsible for providing larger starting torque of the motor (can meet the full load starting of fire pump); the conductor section of the inner cage (lower cage) is larger, which produces the main running torque and presents a relatively hard mechanical external characteristic (suitable for stable working conditions, but it is easy to cause overload for fire pump).

[0005] B. The design of ordinary deep slot motor is basically to achieve the purpose of (A) above.

[0006] C. The structure of ordinary high slip motor is the same as that of ordinary asynchronous motor, except that the rotor conductor is made of high resistivity alloy (can meet the full load starting of fire pump, but the soft mechanical characteristic cannot make the fire pump work in the high efficiency area and has the ability of 1.5 times flow).

[0007] Therefore, there is an urgent need for a scheme to improve the structure of double squirrel cage motor to improve the water supply control of fire water supply system. SUMMARY

[0008] The present application provides a fire water supply system and method based on double squirrel cage motor to solve the above problems existing in the prior art.

[0009] The present application provides a fire water supply system based on double squirrel cage motor, which comprises: a double squirrel cage motor, a centrifugal pump and a water consumption control module;

[0010] The output end of the double squirrel cage motor is connected to the centrifugal pump, and the double squirrel cage motor controls the fire water supply data of the centrifugal pump based on the related parameters provided by the water consumption control module;

[0011] The double squirrel cage motor uses the outer squirrel cage to ensure the starting torque of the fire pump under full load and limit the starting current; the double squirrel cage motor uses the inner squirrel cage to make the centrifugal pump operate in the high efficiency area at the rated operating point, and when the centrifugal pump operates under excess flow, the inner squirrel cage limits the torque of the motor to the maximum torque Tm2 to make the rotating speed of the fire pump set rapidly drop, effectively preventing the centrifugal pump from overloading.

[0012] Preferably, the double squirrel cage motor comprises an outer squirrel cage and an inner squirrel cage; the outer squirrel cage comprises first rotor bars, and the inner squirrel cage comprises second rotor bars; the cross section of the first rotor bars is a long and narrow cross section extending towards the inner squirrel cage, the cross section of the second rotor bars is a circular or elliptical cross section, and the cross section area of the first rotor bars is greater than that of the second rotor bars.

[0013] When the inner squirrel cage operates, the maximum torque Tm2 of the double squirrel cage motor is less than or equal to the set first torque threshold value, and the current through the second rotor bars is less than or equal to the set first current threshold value.

[0014] Preferably, the maximum power capacity of the inner squirrel cage is set, and the maximum power capacity is 70-80% of the maximum shaft power of the double squirrel cage motor.

[0015] The inner squirrel cage ensures the rotating speed of the centrifugal pump at the rated operating point of the flow and the head, so that the centrifugal pump operates in the high efficiency area; the rated operating point includes the rated flow and the rated head; the maximum torque Tm1 of the outer squirrel cage and the maximum torque Tm2 of the inner squirrel cage jointly provide the torque of the fire pump at 1.5 times the rated flow and the specified head.

[0016] When the water consumption of the centrifugal pump exceeds the set rated flow, and the shaft power of the double squirrel cage motor exceeds the maximum power capacity of the inner squirrel cage, Tm2 is limited, and the operating torque of the double squirrel cage motor is Tm 1+ Tm2, which is the maximum torque of the double squirrel cage motor at this time, and when the shaft power of the double squirrel cage motor is greater than the maximum power capacity, the descending rate of the rotating speed of the double squirrel cage motor is greater than or equal to the set rate threshold value.

[0017] Preferably, the water consumption control module comprises:

[0018] a first relationship acquisition unit configured to acquire a first relationship between the rotating speed of the double squirrel cage motor and the flow of the centrifugal pump;

[0019] a second relationship acquisition unit configured to acquire a second relationship between the rotating speed of the double squirrel cage motor and the head of the centrifugal pump;

[0020] a third relationship acquisition unit configured to acquire a third relationship between the rotating speed of the double squirrel cage motor and the shaft power of the double squirrel cage motor;

[0021] determining unit configured to determine the relevant parameter based on the first relationship, the second relationship and the third relationship.

[0022] Preferably, the first rotor bar is a high-resistivity copper alloy material.

[0023] Preferably, the double squirrel cage motor has high slip mechanical characteristics and low starting current and high starting torque at the position of the first rotor bar of the outer rotor cage on the outer circle of the motor rotor and the structure of the first rotor bar and the material of the first rotor bar at the start.

[0024] The application also provides a fire-fighting water supply method based on the double squirrel cage motor, which comprises the following steps:

[0025] S100, setting a double squirrel cage motor, a centrifugal pump and a water control module;

[0026] S200, connecting the output end of the double squirrel cage motor to the centrifugal pump, and controlling the fire-fighting water supply data of the centrifugal pump by the double squirrel cage motor based on the relevant parameter provided by the water control module;

[0027] S300, the double squirrel cage motor uses the maximum torque Tm1 of the outer rotor cage to ensure the torque for starting the fire-fighting pump under full load and limit the starting current, and the Tm1 continues to drop after the motor runs at a normal speed; the maximum torque Tm2 of the inner rotor cage makes the motor have hard mechanical characteristics after the double squirrel cage motor runs at a high speed, and the double squirrel cage motor makes the centrifugal pump run in the high-efficiency area at the rated operating point through the Tm2 of the inner rotor cage during normal operation, but the maximum Tm2 limits the torque when the centrifugal pump runs at an excessive flow rate, so that the speed of the motor drops and the centrifugal pump is effectively prevented from overloading.

[0028] Preferably, the rotor of the double squirrel cage motor comprises an outer rotor cage and an inner rotor cage; the outer rotor cage comprises a first rotor bar, and the inner rotor cage comprises a second rotor bar; the cross section of the first rotor bar is a long and narrow cross section extending to the inner rotor cage; the cross section of the second rotor bar is a circular or elliptical cross section; and the cross section area of the first rotor bar is greater than that of the second rotor bar.

[0029] When the inner rotor cage runs, the maximum torque value of the double squirrel cage motor is less than or equal to a set torque threshold value through the current of the second rotor bar being less than or equal to a set current threshold value.

[0030] Preferably, in the S300, the torque for starting the fire-fighting pump under full load and the limit starting current of the double squirrel cage motor through the outer rotor cage comprise the following steps:

[0031] S301, starting the process of the double squirrel cage motor, based on the first rotor bar of the outer squirrel cage of the rotor of the double squirrel cage motor, the position, structure and the material adopted by the motor rotor, so that Tm1 has high slip ratio.

[0032] Preferably, in the S300, the double squirrel cage motor runs at the normal time, and the centrifugal pump runs in the high efficiency area at the rated operating point through Tm2 of the inner squirrel cage of the rotor, comprising:

[0033] S302, setting the maximum power capacity of the inner squirrel cage, which is 70-80% of the maximum shaft power of the double squirrel cage motor;

[0034] S303, the mechanical characteristics of Tm2 ensure that the centrifugal pump runs at the rated operating point of the flow and the head, so that the centrifugal pump runs in the high efficiency area; the rated operating point includes the rated flow and the rated head;

[0035] S304, when the water consumption of the centrifugal pump exceeds the set rated flow, Tm2 is limited, and the motor synthesizes the maximum torque of Tm1+Tm2 to meet 1.5 times the flow and the specified head; at this time, the shaft power of the double squirrel cage motor is equal to the maximum power capacity, the operating torque of the double squirrel cage motor is the maximum torque, and when the shaft power of the double squirrel cage motor is greater than the maximum power capacity of the inner squirrel cage, the descending rate of the rotating speed of the double squirrel cage motor is greater than or equal to the set rate threshold, and the shaft power of the motor increases with the increase of the flow of the water pump, and the inflection point of the decrease appears.

[0036] Compared with the prior art, the application has the following advantages:

[0037] The application provides a fire-fighting water supply system and method based on a double squirrel cage motor, wherein the system comprises a double squirrel cage motor, a centrifugal pump and a water consumption control module; the output end of the double squirrel cage motor is connected to the centrifugal pump, the double squirrel cage motor controls the fire-fighting water supply data of the centrifugal pump based on the related parameters provided by the water consumption control module; the outer squirrel cage of the rotor of the double squirrel cage motor is used to ensure the starting torque and the limited starting current of the fire-fighting pump under full load; the inner squirrel cage of the rotor of the double squirrel cage motor makes the centrifugal pump run in the high efficiency area at the rated operating point, and when the centrifugal pump runs under over-flow, the maximum torque Tm2 of the inner squirrel cage is used to limit the torque of the motor to make the rotating speed of the fire-fighting pump group drop rapidly, thereby effectively preventing the centrifugal pump from overloading.

[0038] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the application. The objects and other advantages of the application will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

[0039] The technical solutions of the present application are described in further detail below with reference to the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0040] The accompanying drawings are used to provide further understanding of the present application, and form a part of the specification, together with the embodiments of the present application, to explain the present application, and do not constitute a limitation of the present application. In the drawings:

[0041] Figure 1 It is a structural schematic diagram of the fire-fighting water supply system based on the double squirrel cage motor in the embodiment of the present application.

[0042] Figure 2 It is a structural schematic diagram of the outer squirrel cage and the inner squirrel cage of the rotor of the double squirrel cage motor in the embodiment of the present application.

[0043] Figure 3 It is a performance curve comparison diagram of the fire-fighting water pump composed of the double squirrel cage motor and the ordinary motor in the embodiment of the present application.

[0044] Figure 4 It is a characteristic curve diagram of the inner squirrel cage and the outer squirrel cage in the double squirrel cage motor in the embodiment of the present application.

[0045] Figure 5 It is a flow chart of the fire-fighting water supply method based on the double squirrel cage motor in the embodiment of the present application. DETAILED DESCRIPTION

[0046] The preferred embodiments of the present application are described below in combination with the accompanying drawings, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and do not limit the present application.

[0047] The embodiment of the present application provides a fire-fighting water supply system based on a double squirrel cage motor, please refer to Figure 1 The fire-fighting water supply system based on the double squirrel cage motor comprises:

[0048] a double squirrel cage motor, a centrifugal pump and a water use control module;

[0049] The double squirrel cage motor uses the outer squirrel cage of the rotor to ensure the starting torque of the fire-fighting pump under full load and limit the starting current; the double squirrel cage motor uses the inner squirrel cage of the rotor to make the centrifugal pump operate in the high efficiency area at the rated operating point, and when the centrifugal pump operates at an excessive flow rate, the inner squirrel cage is used to limit the torque of the motor to make the rotating speed of the fire-fighting pump set drop rapidly, effectively preventing the centrifugal pump from overloading.

[0050] The working principle of the technical scheme is as follows: the scheme adopted by the embodiment is a double squirrel cage motor, a centrifugal pump and a water control module; the outer squirrel cage of the rotor of the double squirrel cage motor is used to ensure the starting torque of the fire pump under full load and limit the starting current; the inner squirrel cage of the rotor of the double squirrel cage motor enables the centrifugal pump to operate in the high efficiency zone at the rated operating point, and when the centrifugal pump operates at an excess flow rate, the maximum torque Tm2 of the inner squirrel cage is used to limit the torque of the motor to rapidly drop the rotating speed of the fire pump set, effectively preventing the centrifugal pump from being overloaded.

[0051] The beneficial effects of the technical scheme are as follows: the scheme provided by the embodiment sets a double squirrel cage motor, the rotor of the double squirrel cage motor includes an inner squirrel cage (the rated power capacity of the inner squirrel cage is about 75% of the maximum shaft power of the motor) to ensure the rotating speed of the centrifugal fire pump at the rated flow rate and head, so that the water pump can operate in the high efficiency zone. The double squirrel cage motor also includes an outer squirrel cage cooperating with the inner squirrel cage, the outer squirrel cage ensures the starting torque of the motor and limits the starting current to make the motor have a high slip characteristic. When the water consumption of the fire pump exceeds the designed rated flow rate, the maximum torque Tm2 of the inner squirrel cage is used to limit the torque of the motor to rapidly drop the rotating speed of the fire pump set, i.e. the rotating speed n of the motor will rapidly drop, which can effectively prevent the centrifugal pump from being overloaded.

[0052] Firstly, the scheme can meet the rated flow rate and rated head required by the specification, the inner squirrel cage of the rotor can enable the centrifugal pump to operate in the high efficiency zone at the rated operating point, and when the flow rate reaches 1.5 times, the maximum torque Tm1 of the outer squirrel cage and the maximum torque Tm2 of the inner squirrel cage jointly provide the torque of the fire pump at 1.5 times the rated flow rate and the specified head.

[0053] In another embodiment, please refer to Figure 2 The rotor of the double squirrel cage motor includes an outer squirrel cage and an inner squirrel cage; the outer squirrel cage includes first rotor bars, and the inner squirrel cage includes second rotor bars; the cross section of the first rotor bars is a long and narrow cross section extending towards the inner squirrel cage, the cross section of the second rotor bars is a circular or elliptical cross section, and the cross sectional area of the first rotor bars is greater than that of the second rotor bars.

[0054] The current through the second rotor bars is less than or equal to a set first current threshold value, and the maximum torque Tm2 of the double squirrel cage motor is less than or equal to a set first torque threshold value when the inner squirrel cage operates.

[0055] The working principle of the technical solution is as follows: the scheme adopted in the embodiment is an inner and outer squirrel cage structure of a double squirrel cage motor rotor, wherein the outer rotor squirrel cage is designed to be narrow and deep, and the conductor is a high-resistance copper alloy, which takes into account high starting torque and high slip rate operation throughout the process. The conductor cross section of the inner rotor squirrel cage is relatively small, so that the current flowing through the inner squirrel cage conductor is relatively small, resulting in a relatively small maximum torque Tm2 value of the inner squirrel cage.

[0056] Specifically, the shape of the outer rotor squirrel cage is similar to that of a deep slot asynchronous motor, and the rotor bar cross section (see Figure 2 ), but the bar is made of a high-resistance copper alloy material, so it has excellent starting performance. After the motor completes the starting process and the speed increases, it presents a super-high slip mechanical characteristic curve, as shown in Figure 4 , the outer squirrel cage starts to operate, the motor speed gradually increases, and the torque increases, and the motor slip rate significantly increases.

[0057] The structure of the inner rotor squirrel cage is that the conductor cross section of the inner squirrel cage is designed to be small (see Figure 2 ), and the maximum power capacity is 70-80% of the maximum shaft power of the double squirrel cage motor, preferably about 75%. The speed of the centrifugal fire pump at the rated operating point of flow and head can make the pump operate in the high efficiency area. When the water consumption of the fire pump exceeds the designed rated flow point, the shaft power of the centrifugal pump exceeds 75% of the maximum power of the motor, and the motor reaches the maximum torque value Tm2 when it reaches 75% of the maximum power, as shown in Figure 4 , the motor speed n drops rapidly.

[0058] Therefore, the improved double squirrel cage motor provided in the embodiment is different from the traditional double squirrel cage motor. The improved double squirrel cage motor has a large cross-sectional area outer squirrel cage and a small cross-sectional area inner squirrel cage. The large cross-sectional area outer squirrel cage has a high slip rate, and its speed drop will increase with the increase of the motor torque, so it has a high starting torque and a soft mechanical characteristic. In addition, the small cross-sectional area inner squirrel cage has a relatively small current flowing through the inner squirrel cage conductor after the motor starts, resulting in a relatively small maximum torque value Tm2 of the motor, but it has a hard mechanical characteristic in the rated power range. The improved double squirrel cage motor based on the improved outer squirrel cage structure and inner squirrel cage structure has excellent starting performance, and ensures the speed of the centrifugal fire pump at the rated operating point of flow and head, so that the pump operates in the high efficiency area. In addition, the torque limitation effectively prevents the fire pump from overloading during the super-flow operation.

[0059] Please refer to Figure 3 , the left vertical coordinate is the motor speed n, the lower side is the head H, the upper side of the right vertical coordinate is the motor slip rate, the lower side is the motor shaft power P, and the horizontal coordinate is the flow Q. FromFigure 3 It can be seen that the embodiment provides an improvement on the conventional double squirrel cage motor, so that the improved double squirrel cage motor has excellent starting performance and realizes the super high slip characteristic when the flow rate exceeds the rated flow rate, so that the motor speed and the flow rate of the water pump will quickly drop, and the water pump will not cause cavitation problems under the condition of low speed and low flow rate.

[0060] In another embodiment, the maximum power capacity of the inner squirrel cage is set, and the maximum power capacity is 70-80% of the maximum shaft power of the double squirrel cage motor.

[0061] The inner squirrel cage ensures the speed of the centrifugal pump at the rated flow rate and head, so that the centrifugal pump operates in the high efficiency region; the rated working condition point includes the rated flow rate and the rated head; the maximum torque Tm1 of the outer squirrel cage and the maximum torque Tm2 of the inner squirrel cage jointly provide the torque of the fire pump when the rated flow rate is 1.5 times and the specified head is reached.

[0062] The working principle of the above technical solution is that the maximum power capacity of the inner squirrel cage is set, and the maximum power capacity is 70-80% of the maximum shaft power of the double squirrel cage motor; the inner squirrel cage ensures the speed of the centrifugal pump at the rated flow rate and head, so that the centrifugal pump operates in the high efficiency region; the rated working condition point includes the rated flow rate and the rated head; the maximum torque Tm1 of the outer squirrel cage and the maximum torque Tm2 of the inner squirrel cage jointly provide the torque of the fire pump when the rated flow rate is 1.5 times and the specified head is reached. When the water consumption of the centrifugal pump exceeds the set rated flow rate, and the shaft power of the double squirrel cage motor is equal to the maximum power capacity, the operating torque of the double squirrel cage motor is Tm 1+ Tm2, which is the maximum torque of the double squirrel cage motor, and when the shaft power of the double squirrel cage motor is greater than the maximum power capacity, the speed drop rate of the double squirrel cage motor is greater than or equal to the set speed threshold.

[0063] The beneficial effects of the above technical solution are that the maximum power capacity of the motor rotor inner squirrel cage is set by the scheme provided in the embodiment, and the maximum power capacity is 70-80% of the maximum shaft power of the double squirrel cage motor; the inner squirrel cage ensures the speed of the centrifugal pump at the rated flow rate and head, so that the centrifugal pump operates in the high efficiency region; the rated working condition point includes the rated flow rate and the rated head; the maximum torque Tm1 of the outer squirrel cage and the maximum torque Tm2 of the inner squirrel cage jointly provide the torque of the fire pump when the rated flow rate is 1.5 times and the specified head is reached. When the water consumption of the centrifugal pump exceeds the set rated flow rate, and the shaft power of the double squirrel cage motor is equal to the maximum power capacity, the operating torque of the double squirrel cage motor is Tm 1+Tm2, which is the maximum torque of the double squirrel cage motor, when the shaft power of the double squirrel cage motor is greater than the maximum power capacity, the speed of the double squirrel cage motor decreases at a rate greater than or equal to the set rate threshold.

[0064] In another embodiment, the water control module comprises:

[0065] a first relationship acquisition unit configured to acquire a first relationship between the speed of the double squirrel cage motor and the flow rate of the centrifugal pump;

[0066] a second relationship acquisition unit configured to acquire a second relationship between the speed of the double squirrel cage motor and the head of the centrifugal pump;

[0067] a third relationship acquisition unit configured to acquire a third relationship between the speed of the double squirrel cage motor and the shaft power of the double squirrel cage motor;

[0068] a determination unit configured to determine a relevant parameter based on the first relationship, the second relationship, and the third relationship.

[0069] The working principle of the above technical solution is as follows: the scheme adopted in the embodiment is that the water control module comprises: a first relationship acquisition unit configured to acquire a first relationship between the speed of the double squirrel cage motor and the flow rate of the centrifugal pump; a second relationship acquisition unit configured to acquire a second relationship between the speed of the double squirrel cage motor and the head of the centrifugal pump; a third relationship acquisition unit configured to acquire a third relationship between the speed of the double squirrel cage motor and the shaft power of the double squirrel cage motor; and a determination unit configured to determine a relevant parameter based on the first relationship, the second relationship, and the third relationship.

[0070] The relationship formula among the flow rate, the head, the shaft power, and the speed of the centrifugal pump is:

[0071]

[0072]

[0073]

[0074] wherein Q, H, P, and n respectively represent the flow rate, the head, the shaft power, and the speed of the water pump;

[0075] The change of the flow rate Q of the water pump is in a proportional relationship with the change of the speed n;

[0076] The change of the head H of the water pump is in a proportional relationship with the square of the speed n;

[0077] The shaft power P of the water pump is in a proportional relationship with the cube of the speed n;

[0078] Therefore, the shaft power P of the water pump can be greatly changed by changing the speed n.

[0079] In another embodiment, the first rotor bar is a high-resistivity copper alloy material.

[0080] In another embodiment, the double squirrel cage motor, at the time of starting, due to the first rotor bar of the outer squirrel cage being in the position of the motor rotor close to the outer circle, the structure and the material adopted, Tm1 presents high slip mechanical characteristics, and a lower starting current and a higher starting torque; the second rotor bar of the inner squirrel cage does not work in the process of starting due to being in the position of the motor rotor close to the inner circle.

[0081] The working principle of the above technical solution is that the scheme adopted in the embodiment is that the double squirrel cage motor, at the time of starting, due to the first rotor bar of the outer squirrel cage being in the position of the motor rotor close to the outer circle, the structure and the material adopted, Tm1 presents high slip mechanical characteristics, and a lower starting current and a higher starting torque; the second rotor bar of the inner squirrel cage does not work in the process of starting due to being in the position of the motor rotor close to the inner circle.

[0082] In another embodiment, the present application also provides a fire-fighting water supply method based on a double squirrel cage motor, please refer to Figure 5 The method comprises:

[0083] S100, a double squirrel cage motor, a centrifugal pump and a water control module are arranged;

[0084] S200, the output end of the double squirrel cage motor is connected to the centrifugal pump, and the double squirrel cage motor controls the fire-fighting water supply data of the centrifugal pump based on the related parameters provided by the water control module;

[0085] S300, the double squirrel cage motor uses the maximum torque Tm1 of the outer squirrel cage to ensure the torque of the full load starting of the fire-fighting pump and limit the starting current, and after the motor runs at a normal speed, Tm1 continues to drop; after the double squirrel cage motor runs at a speed, the maximum torque Tm2 of the inner squirrel cage makes the motor present a hard mechanical characteristic, that is, the inner squirrel cage Tm2 can make the centrifugal pump run in the high efficiency zone at the rated operating point, but when the centrifugal pump runs at an excess flow rate, the maximum Tm2 limits the torque, so that the speed of the motor drops and effectively prevents the centrifugal pump from being overloaded.

[0086] The working principle of the technical solution is as follows: the scheme adopted in the embodiment is a fire water supply method based on a double squirrel cage motor, and the scheme is characterized in that the scheme comprises: a double squirrel cage motor, a centrifugal pump and a water control module; the output end of the double squirrel cage motor is connected to the centrifugal pump, and the double squirrel cage motor controls fire water supply data of the centrifugal pump based on relevant parameters provided by the water control module; the double squirrel cage motor uses the maximum torque Tm1 of the outer squirrel cage to ensure the torque for starting the fire pump under full load and limit the starting current, and the Tm1 continues to drop after the motor runs at a normal speed; after the double squirrel cage motor runs at a high speed, the maximum torque Tm2 of the inner squirrel cage makes the motor present a relatively hard mechanical characteristic, that is, the Tm2 of the inner squirrel cage can make the centrifugal pump run in the high-efficiency zone at the rated operating point, but when the centrifugal pump runs under excess flow, the maximum Tm2 limits the torque, so that the speed of the motor drops, thereby effectively preventing the centrifugal pump from being overloaded.

[0087] In another embodiment, the double squirrel cage motor comprises an outer squirrel cage and an inner squirrel cage; the outer squirrel cage comprises first rotor bars, and the inner squirrel cage comprises second rotor bars; the cross section of the first rotor bars is a long and narrow cross section extending towards the inner squirrel cage; the cross section of the second rotor bars is a circular or elliptical cross section; and the cross section area of the first rotor bars is greater than that of the second rotor bars.

[0088] When the inner squirrel cage runs, the maximum torque Tm2 of the double squirrel cage motor is less than or equal to a set torque threshold value, and the current through the second rotor bars is less than or equal to a set current threshold value.

[0089] In another embodiment, in the S300, the double squirrel cage motor uses the outer squirrel cage to ensure the torque for starting the fire pump under full load and limit the starting current, and the process of starting the double squirrel cage motor comprises:

[0090] S301, the process of starting the double squirrel cage motor, based on the first rotor bars of the outer squirrel cage of the double squirrel cage motor, the position of the rotor bars, the structure thereof and the material adopted thereby, the Tm1 has a high slip rate.

[0091] The working principle of the technical solution is as follows: in the S300, the double squirrel cage motor uses the outer squirrel cage to ensure the torque for starting the fire pump under full load and limit the starting current, and the process of starting the double squirrel cage motor comprises: S301, based on the first rotor bars of the outer squirrel cage of the double squirrel cage motor, the position of the rotor bars, the structure thereof and the material adopted thereby, the Tm1 has a high slip rate.

[0092] In another embodiment, in the S300, when the double squirrel cage motor runs normally, the Tm2 of the inner squirrel cage makes the centrifugal pump run in the high-efficiency zone at the rated operating point, and the process comprises:

[0093] S302, set the maximum power capacity of the inner squirrel cage, the maximum power capacity is 70-80% of the maximum shaft power of the double squirrel cage motor;

[0094] S303, the mechanical property of Tm2 guarantees the rotation speed of the centrifugal pump at the rated flow and head, so that the centrifugal pump operates in the high efficiency area;

[0095] S304, when the water consumption of the centrifugal pump exceeds the set rated flow, Tm2 is limited, the motor synthesizes the maximum torque of Tm1+Tm2 to meet 1.5 times the flow and the specified head; at this time, the shaft power of the double squirrel cage motor is equal to the maximum power capacity, and the operating torque of the double squirrel cage motor is the maximum torque, as shown by the solid line "double squirrel cage motor mechanical property" in the figure, when the shaft power of the double squirrel cage motor is greater than the maximum power capacity of the inner squirrel cage, the descending rate of the rotation speed of the double squirrel cage motor (about 17%) is greater than or equal to the set rate threshold, and the shaft power of the motor increases with the increase of the flow of the water pump, and the inflection point of the descending shaft power appears. Figure 4

[0096] The working principle of the above technical scheme is that: in the S300, the double squirrel cage motor operates normally, Tm2 of the inner squirrel cage makes the centrifugal pump operate in the high efficiency area at the rated working point, including: S302, setting the maximum power capacity of the inner squirrel cage, the maximum power capacity is 70-80% of the maximum shaft power of the double squirrel cage motor; S303, the mechanical property of Tm2 guarantees the rotation speed of the centrifugal pump at the rated flow and head, so that the centrifugal pump operates in the high efficiency area; the rated working point includes the rated flow and the rated head; S304, when the water consumption of the centrifugal pump exceeds the set rated flow, Tm2 is limited, the motor synthesizes the maximum torque of Tm1+Tm2 to meet 1.5 times the flow and the specified head; at this time, the shaft power of the double squirrel cage motor is equal to the maximum power capacity, and the operating torque of the double squirrel cage motor is the maximum torque, as shown by the solid line "double squirrel cage motor mechanical property" in the figure, when the shaft power of the double squirrel cage motor is greater than the maximum power capacity of the inner squirrel cage, the descending rate of the rotation speed of the double squirrel cage motor (about 17%) is greater than or equal to the set rate threshold, and the shaft power of the motor increases with the increase of the flow of the water pump, and the inflection point of the descending shaft power appears. Figure 4

[0097] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.​​

Claims

1. A fire-fighting water supply system based on a dual-cage electric motor, characterized in that, include: Dual squirrel-cage motor, centrifugal pump, and water control module; The output end of the dual-cage motor is connected to the centrifugal pump, and the dual-cage motor controls the fire water supply data of the centrifugal pump based on the relevant parameters provided by the water control module. The dual-cage motor uses the outer cage of the rotor to ensure the starting torque of the fire pump under full load and limit the starting current; the dual-cage motor uses the inner cage of the rotor to ensure that the centrifugal pump operates in the high-efficiency zone at the rated operating point, and when the centrifugal pump is running at overflow, the maximum torque Tm2 of the inner cage is used to limit the torque of the motor and cause the speed of the fire pump set to drop rapidly, effectively preventing the centrifugal pump from being overloaded. The dual-cage motor includes an outer cage and an inner cage; the outer cage includes a first rotor bar, and the inner cage includes a second rotor bar. The cross-section of the first rotor bar is a long, narrow cross-section extending towards the inner cage, and the cross-section of the second rotor bar is a circular or elliptical cross-section. The cross-sectional area of ​​the first rotor bar is larger than that of the second rotor bar. When the current through the second rotor bar is less than or equal to the set first current threshold, the maximum torque Tm2 value of the double squirrel cage motor is less than or equal to the set first torque threshold when the inner squirrel cage is running. The maximum power capacity of the inner cage is set to be 70-80% of the maximum shaft power of the dual-cage motor. The inner squirrel cage ensures the centrifugal pump operates at the rated flow and head, allowing the centrifugal pump to operate in the high-efficiency zone; the rated operating point includes the rated flow and rated head; the maximum torque Tm1 of the outer squirrel cage and the maximum torque Tm2 of the inner squirrel cage work together to provide the fire pump with 1.5 times the rated flow and the torque required to reach the specified head. When the water consumption of the centrifugal pump exceeds the set rated flow rate, and when the shaft power of the dual-cage motor exceeds the maximum power capacity of the inner cage, the operating torque of the dual-cage motor is Tm. 1+ Tm2 is the maximum torque of the dual-cage motor. When the shaft power of the dual-cage motor is greater than the maximum power capacity of the inner cage, the rate of decrease of the speed of the dual-cage motor is greater than or equal to the set speed threshold.

2. The fire-fighting water supply system based on a dual-cage motor according to claim 1, characterized in that, The water control module includes: The first relationship acquisition unit is used to obtain the first relationship between the rotational speed of the dual squirrel-cage motor and the flow rate of the centrifugal pump. The second relationship acquisition unit is used to obtain the second relationship between the rotational speed of the dual squirrel-cage motor and the head of the centrifugal pump. The third relationship acquisition unit is used to obtain the third relationship between the rotational speed of the double squirrel-cage motor and the shaft power of the double squirrel-cage motor. The determination unit is used to determine relevant parameters based on the first, second, and third relations.

3. The fire-fighting water supply system based on a dual-cage motor according to claim 1, characterized in that, The first rotor bar is made of a copper alloy material with high resistivity.

4. The fire-fighting water supply system based on a dual-cage motor according to claim 1, characterized in that, When a double squirrel-cage motor starts, the first rotor bar of the outer squirrel cage is located near the outer circle of the motor rotor. Due to its structure and the material of its bars, Tm1 exhibits high slip mechanical characteristics, as well as low starting current and high starting torque. The second rotor bar of the inner squirrel cage is located near the inner circle of the motor rotor and therefore does not function during startup.

5. A fire-fighting water supply method based on a dual-cage electric motor, characterized in that, include: S100 is equipped with dual squirrel cage motors, centrifugal pumps, and a water control module; S200, the output end of the dual-cage motor is connected to the centrifugal pump, and the dual-cage motor controls the fire water supply data of the centrifugal pump based on the relevant parameters provided by the water control module; S300, the dual-cage motor uses the maximum torque Tm1 of the outer cage of the rotor to ensure the torque for the fire pump to start under full load and to limit the starting current. After the motor runs at normal speed, Tm1 continues to drop, exhibiting a high slip mechanical characteristic throughout. After the dual-cage motor speeds up, the maximum torque Tm2 of the inner cage makes the motor exhibit a stiffer mechanical characteristic. During normal operation, the dual-cage motor mainly uses the Tm2 of the inner cage to keep the centrifugal pump running in the high-efficiency zone at the rated operating point. However, when the centrifugal pump runs at overflow, the maximum Tm2 limits the torque, causing the motor speed to drop and effectively preventing the centrifugal pump from overloading. The dual-cage motor includes an outer cage and an inner cage; the outer cage includes a first rotor bar, and the inner cage includes a second rotor bar. The cross-section of the first rotor bar is a long, narrow cross-section extending towards the inner cage, and the cross-section of the second rotor bar is a circular or elliptical cross-section. The cross-sectional area of ​​the first rotor bar is larger than that of the second rotor bar. When the current through the second rotor bar is less than or equal to the set current threshold, the maximum torque value of the double squirrel cage motor is less than or equal to the set torque threshold when the inner squirrel cage is running. In S300, during normal operation, the dual-cage motor ensures that the centrifugal pump operates in its high-efficiency zone at the rated operating point through the Tm2 of the inner cage of the rotor, including: S302, Set the maximum power capacity of the inner squirrel cage, wherein the maximum power capacity is 70-80% of the maximum shaft power of the dual squirrel cage motor; S303, the mechanical characteristics of Tm2 ensure the speed of the centrifugal pump at the rated flow and head, so that the centrifugal pump operates in the high-efficiency range; the rated operating point includes the rated flow and rated head; S304, when the water consumption of the centrifugal pump exceeds the set rated flow, Tm2 is limited, and the motor's combined maximum torque from Tm1+Tm2 satisfies 1.5 times the flow and its specified head; at this time, the shaft power of the double squirrel-cage motor is equal to the maximum power capacity, and the operating torque of the double squirrel-cage motor is the maximum torque. When the shaft power of the double squirrel-cage motor is greater than the maximum power capacity of the inner squirrel cage, the rate of decrease of the double squirrel-cage motor speed is greater than or equal to the set rate threshold, and the shaft power of the motor, which increases with the increase of the water pump flow, reaches a point of inflection of decrease.

6. The fire-fighting water supply method based on a dual-cage electric motor according to claim 5, characterized in that, In S300, the dual-cage motor, through the outer squirrel cage of the rotor, ensures the torque for full-load starting of the fire pump and limits the starting current, including: S301, the process of starting the double squirrel-cage motor, based on the position, structure and material of the first rotor bar of the outer squirrel cage of the double squirrel-cage motor, Tm1 has a high slip rate throughout the entire process.

Images