Unit series connection type foldable frequency converter for large-scale motor experiment table
The unit series foldable inverter solves the problem of large capacity and high cost of inverters on large motor test benches, realizes precise control and experiments on super-large motors, avoids transformer magnetic bias, and meets the experimental requirements of multiple voltage standards.
Patent Information
- Application Number
- CN202422752398.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Priority Date
- 2024-09-05
- Filing Date
- 2024-11-12
- Publication Date
- 2025-09-23
- Estimated Expiration
- 2034-11-12
AI Technical Summary
The inverters of existing large-scale motor test benches have huge capacity and are expensive. They cannot achieve precise control and superimposed frequency experiments on ultra-large motors, and there is a problem of output transformer bias.
A unit series foldable inverter is used, including the first and second variable frequency power supplies, which can be used in series or parallel to meet the motor test requirements of different voltage standards, eliminate the step-up transformer, and achieve precise control of the vector control algorithm and full-voltage superposition frequency experiment of super-large motors.
It achieves precise control of the motor, meets the experimental requirements of various voltage standards, avoids the problem of output transformer magnetic bias, and supports the experiment of super-large motors.
Smart Images
Figure CN223379090U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of large motor test benches, and in particular relates to a unit series type foldable frequency converter used for the large motor test bench. Background Art
[0002] Currently, large motor experiments all use high-voltage, high-power inverters for direct drive. Motor voltage standards are as follows: 3kV, 6kV, 10kV, and 13.8kV. Taking a motor with an output power of 13,300kW, a power factor of 0.9, and an efficiency of 97% as an example, the rated currents for motors of different voltage standards are as follows:
[0003] Rated voltage Rated current (A) 3kV 1103 6kV 552 10kV 331 13.8kV 240
[0004] If the motor test bench is to meet the experimental requirements of the motors of the above voltage standards, then the selection of the inverter must meet the requirements of both the highest voltage and the maximum current. That is, the output voltage of the inverter is 13.8kV and the output current is 1103A. The capacity of this inverter needs to be 14000kVA, which is huge and expensive.
[0005] To solve this problem, the currently commonly used approach is to select a smaller inverter capacity and use a combination of step-up and step-down transformers for the output to meet the experimental requirements of motors of various voltage specifications.
[0006] The disadvantages of this method are: (1) Due to the obstruction of the output transformer, the vector control algorithm cannot achieve precise control of the motor through the output transformer and can only use V / F control, which makes it impossible to complete some special motor experimental projects. (2) The existence of the output transformer cannot complete the superposition frequency experiment of super-large motors. If the output transformer is bypassed, the problem of insufficient inverter capacity will also be faced. (3) The bias problem of the output transformer is difficult to control. Since the output transformer operates in the full frequency range of 0-60Hz, it is difficult to ensure that the transformer design does not have bias in the full frequency range. Utility Model Content
[0007] In order to solve the above technical problems, the utility model provides a unit series foldable inverter for a large motor test bench. The first variable frequency power supply and the second variable frequency power supply can be used separately, or they can be used in series or in parallel to meet the experimental requirements of motors of various voltage standards.
[0008] The purpose of this utility model is achieved through the following technical solutions:
[0009] A unit series foldable inverter for a large motor test bench includes a first variable frequency power supply and a second variable frequency power supply. The input end of the first variable frequency power supply is connected to a first power grid busbar via a first switch cabinet, and the output end of the first variable frequency power supply is connected to a first isolation switch. Node a1 of the first isolation switch is connected to a first motor, and node b1 of the first isolation switch is connected to a second isolation switch. Node a2 of the second isolation switch is connected to a balancing inductor, and the midpoint of the balancing inductor is connected to a second motor. The input end of the second variable frequency power supply is connected to a second power grid busbar via a second switch cabinet, and the output end of the second variable frequency power supply is connected to a third isolation switch and a fourth isolation switch. Node a3 of the third isolation switch is connected to node b2 of the second isolation switch, and node b3 of the third isolation switch is connected to the balancing inductor. Node a4 of the fourth isolation switch is connected to a third motor, and node b4 of the fourth isolation switch is grounded.
[0010] Preferably, the first variable frequency power supply includes a first phase-shifting transformer and a first power unit, the first power unit includes a first A-phase power unit, a first B-phase power unit and a first C-phase power unit, and each phase is composed of n power modules connected in series.
[0011] Preferably, the second variable frequency power supply includes a second phase-shifting transformer and a second power unit, the second power unit includes a second A-phase power unit, a second B-phase power unit and a second C-phase power unit, and each phase is composed of n power modules connected in series.
[0012] Preferably, the voltage of the first motor is 3KV or 6KV, and the current of the first motor is less than 880A.
[0013] Preferably, the voltage of the second motor is 3KV or 6KV, and the current of the second motor is greater than 880A.
[0014] Preferably, the voltage of the third motor is 10KV or 13.8KV.
[0015] The beneficial effects of this technical solution are as follows:
[0016] 1. The utility model provides a unit series foldable inverter for a large motor test bench. The first variable frequency power supply and the second variable frequency power supply can be used separately, or they can be used in series or in parallel to meet the experimental requirements of motors of various voltage standards.
[0017] 2. The utility model provides a unit series foldable inverter for a large motor test bench. Without a step-up transformer, the vector control algorithm can achieve precise control of the motor, meeting the needs of some experimental projects that require a vector control algorithm.
[0018] 3. The utility model provides a unit series foldable inverter for a large motor test bench, which can realize full voltage and frequency overlapping experiments on super-large motors.
[0019] 4. The utility model provides a unit series foldable inverter for a large motor test bench, which avoids the problem of magnetic bias of the output transformer. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is a structural diagram of the present utility model.
[0021] Among them: 1. First variable frequency power supply; 101. First phase-shifting transformer; 102. First power unit; 2. Second variable frequency power supply; 201. Second phase-shifting transformer; 202. Second power unit; 3. First switchgear; 4. First grid bus; 5. First isolation switch; 6. First motor; 7. Second isolation switch; 8. Balancing reactor; 9. Second motor; 10. Second switchgear; 11. Second grid bus; 12. Third isolation switch; 13. Fourth isolation switch; 14. Third motor. DETAILED DESCRIPTION
[0022] The present invention will be further described in detail below with reference to the embodiments, but the embodiments of the present invention are not limited thereto.
[0023] Example 1
[0024] like Figure 1 As shown, a unit series foldable inverter for a large motor test bench includes a first variable frequency power supply 1 and a second variable frequency power supply 2. The input end of the first variable frequency power supply 1 is connected to the first grid bus 4 through a first switch cabinet 3. The output end of the first variable frequency power supply 1 is connected to a first isolation switch 5. The node a1 of the first isolation switch 5 is connected to a first motor 6. The node b1 of the first isolation switch 5 is connected to a second isolation switch 7. The node a2 of the second isolation switch 7 is connected to a balancing reactor 8. The balancing reactor The midpoint of 8 is connected to the second motor 9; the input end of the second variable-frequency power supply 2 is connected to the second grid bus 11 through the second switch cabinet 10, and the output end of the second variable-frequency power supply 2 is connected to the third isolation switch 12 and the fourth isolation switch 13, the node a3 of the third isolation switch 12 is connected to the node b2 of the second isolation switch 7, the node b3 of the third isolation switch 12 is connected to the balancing inductor 8, the node a4 of the fourth isolation switch 13 is connected to the third motor 14, and the node b4 of the fourth isolation switch 13 is grounded.
[0025] Example 2
[0026] The difference between this embodiment and embodiment 1 is that the first variable frequency power supply 1 includes a first phase-shifting transformer 101 and a first power unit 102. The first power unit 102 includes a first A-phase power unit, a first B-phase power unit, and a first C-phase power unit, each phase of which is composed of n power modules connected in series. The first phase-shifting transformer 101 supplies power to the first power unit 102 through voltage division. The first A-phase power unit includes an A11 power module, an A12 power module, an A13 power module, an A14 power module, an A15 power module, and an A16 power module; the first B-phase power unit includes a B11 power module, a B12 power module, a B13 power module, a B14 power module, a B15 power module, and a B16 power module; and the first C-phase power unit includes a C11 power module, a C12 power module, a C13 power module, a C14 power module, a C15 power module, and a C16 power module.
[0027] The second variable frequency power supply 2 includes a second phase-shifting transformer 201 and a second power unit 202. The second power unit 202 includes a second A-phase power unit, a second B-phase power unit, and a second C-phase power unit. Each phase is composed of n power modules connected in series. The second phase-shifting transformer 201 supplies power to the second power unit 202 through voltage division. The second A-phase power unit includes a power module A21, a power module A22, a power module A23, a power module A24, a power module A25, and a power module A26; the second B-phase power unit includes a power module B21, a power module B22, a power module B23, a power module B24, a power module B25, and a power module B26; and the second C-phase power unit includes a power module C21, a power module C22, a power module C23, a power module C24, a power module C25, and a power module C26.
[0028] The voltage of the first motor 6 is 3KV or 6KV, and the current of the first motor 6 is less than 880A.
[0029] The voltage of the second motor 9 is 3KV or 6KV, and the current of the second motor 9 is greater than 880A.
[0030] The voltage of the third motor 14 is 10KV or 13.8KV.
[0031] The first isolation switch 5 , the second isolation switch 7 , the third isolation switch 12 and the fourth isolation switch 13 are all single-pole double-throw switches.
[0032] Example 3
[0033] The difference between this embodiment and embodiment 2 is that the IGBTs used in each unit have different withstand voltages, and the number of power units connected in series for different voltage levels is different. Taking a 1700V withstand voltage IGBT as an example, the number of units connected in series for different voltage levels of the inverter is as follows:
[0034] Voltage level Unit series number 3kV Level 3 5kV Level 5 10kV Level 8 13.8kV Level 12
[0035] The specific implementation method is: disconnect the inverter with a rated output voltage of 13.8kV and 12-level units in series from the middle to become two inverters with 6-level units in series and a rated output voltage of 6kV. Use a single-pole double-throw switch to control the power units of each phase of the two inverters to be connected in series to form an inverter with 12-level units in series, realizing 10kV and 13.8kV voltage output. The two inverters can also be connected in parallel to realize 3kV and 6kV voltage output, but the current can be doubled compared to the series state.
[0036] There are three working conditions when this device is used.
[0037] Working condition 1: When testing the first motor 6:
[0038] 1. Switch the first isolation switch 5 (QS1) to node a1.
[0039] 2. Start the first variable frequency power supply 1, and use the first variable frequency power supply 1 to drive the motor under test (ie, the first motor 6) to run.
[0040] Working condition 2: When testing the second motor 9:
[0041] 1. Switch the first isolation switch 5 (QS1) to node b1.
[0042] 2. Throw the second isolation switch 7 (QS2) to node a2.
[0043] 3. Throw the third isolation switch 12 (QS3) to node b3.
[0044] 4. Throw the fourth isolation switch 13 (QS4) to node b4.
[0045] 5. Start the first variable frequency power supply 1 and the second variable frequency power supply 2. The first variable frequency power supply 1 and the second variable frequency power supply 2 are connected in parallel to drive the motor under test (ie, the second motor 9) to run.
[0046] Working condition 3: When testing the third motor 14:
[0047] 1. Switch the first isolation switch 5 (QS1) to node b1.
[0048] 2. Switch the second isolation switch 7 (QS2) to node b2.
[0049] 3. Throw the third isolation switch 12 (QS3) to node a3.
[0050] 4. Throw the fourth isolation switch 13 (QS4) to node a4.
[0051] 5. Start the first variable frequency power supply 1 and the second variable frequency power supply 2. The first variable frequency power supply 1 and the second variable frequency power supply 2 are connected in series to drive the motor under test (ie, the third motor 14) to run.
[0052] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention falls within the scope of protection of the present invention.
Claims
1. A unit series foldable inverter for a large motor test bench, characterized by: The invention comprises a first variable frequency power supply (1) and a second variable frequency power supply (2), wherein the input end of the first variable frequency power supply (1) is connected to a first power grid bus (4) through a first switch cabinet (3), the output end of the first variable frequency power supply (1) is connected to a first isolation knife switch (5), a node a1 of the first isolation knife switch (5) is connected to a first motor (6), a node b1 of the first isolation knife switch (5) is connected to a second isolation knife switch (7), a node a2 of the second isolation knife switch (7) is connected to a balancing reactor (8), a midpoint of the balancing reactor (8) is connected to a second motor (9), and a second motor (9) is connected to a balancing reactor (8). The input end of the second variable frequency power supply (2) is connected to the second power grid bus (11) through the second switch cabinet (10), the output end of the second variable frequency power supply (2) is connected to the third isolation knife switch (12) and the fourth isolation knife switch (13), the node a3 of the third isolation knife switch (12) is connected to the node b2 of the second isolation knife switch (7), the node b3 of the third isolation knife switch (12) is connected to the balancing reactor (8), the node a4 of the fourth isolation knife switch (13) is connected to the third motor (14), and the node b4 of the fourth isolation knife switch (13) is grounded.
2. The unit series foldable inverter for a large motor test bench according to claim 1, characterized in that: The first variable frequency power supply (1) comprises a first phase-shifting transformer (101) and a first power unit (102), wherein the first power unit (102) comprises a first A-phase power unit, a first B-phase power unit and a first C-phase power unit, and each phase is formed by n power modules connected in series.
3. The unit series foldable inverter for a large motor test bench according to claim 1, characterized in that: The second variable frequency power supply (2) comprises a second phase-shifting transformer (201) and a second power unit (202), wherein the second power unit (202) comprises a second A-phase power unit, a second B-phase power unit, and a second C-phase power unit, and each phase is formed by n power modules connected in series.
4. The unit series foldable inverter for a large motor test bench according to claim 1, characterized in that: The voltage of the first motor (6) is 3KV or 6KV, and the current of the first motor (6) is less than 880A.
5. The unit series foldable inverter for a large motor test bench according to claim 1, characterized in that: The voltage of the second motor (9) is 3KV or 6KV, and the current of the second motor (9) is greater than 880A.
6. The unit series foldable inverter for a large motor test bench according to claim 1, characterized in that: The voltage of the third motor (14) is 10KV or 13.8KV.