Direct current link series fault-tolerant permanent magnet synchronous motor drive system and method

Abstract

This invention discloses a DC-link series-type fault-tolerant permanent magnet synchronous motor drive system and method. The system includes a DC power supply, N permanent magnet synchronous motors, and N*a unit inverters. The number of windings in the permanent magnet synchronous motors is *a*, the number of phases in each winding unit is *m*, and the number of phases in each inverter is *m*. There is a one-to-one correspondence between the N*a unit inverters and the N*a windings. When a power switch short-circuit fault occurs, all power switches in the corresponding unit inverter are turned on, putting the winding of that unit motor in a short-circuit state and providing a current path for the normal unit inverters on the same series branch. When a power switch open-circuit fault occurs, the normal bridge arm power switch of that unit inverter is turned on, putting the winding of that unit motor in a short-circuit state and providing a current path for the normal unit inverters on the same series branch. This invention enables fault-tolerant operation for power switch open-circuit and short-circuit faults.

Description

Technical Field

[0001] This invention relates to the field of fault-tolerant drive motor technology, and in particular to a DC-link series-type fault-tolerant permanent magnet synchronous motor drive system and method. Background Technology

[0002] Permanent magnet synchronous motor drive systems offer advantages such as high power density and high efficiency, leading to their widespread application in new energy vehicles and electric drives. Electric vehicle drive systems and aerospace electric propulsion systems place increasingly higher demands on the reliability of motor drive systems. Currently, to improve reliability, motors often employ multi-phase three-phase winding structures, while permanent magnet motor drive systems typically utilize a parallel DC link configuration, with each drive motor's inverter using the same DC link voltage. When a short-circuit fault occurs in the permanent magnet drive system, especially a shoot-through fault in the inverter, it can lead to a DC power supply failure, affecting the normal operation of other drive motors.

[0003] Existing research on fault-tolerant permanent magnet synchronous motor drive systems mainly focuses on fault-tolerant control for open-circuit faults. Research on fault tolerance for short-circuit faults is relatively limited, but the impact of such faults is significant. For example, a shoot-through fault in an inverter bridge arm can cause a power supply short circuit, leading to the windings powered by that power supply failing to operate normally. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the deficiencies mentioned in the background art by providing a DC-link series-type fault-tolerant permanent magnet synchronous motor drive system and method.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A DC-link series-type fault-tolerant permanent magnet synchronous motor drive system includes a DC power supply, N permanent magnet synchronous motors, and N*a unit inverters, where N and a are natural numbers greater than or equal to 1.

[0007] The permanent magnet synchronous motor has a winding number of a, and the winding unit has a phase number of m, where m is a natural number greater than or equal to 3; the inverter has a phase number of m; the N permanent magnet synchronous motors have a total of N*a windings, and the N*a unit inverters correspond one-to-one with the N*a windings;

[0008] The DC links of the N*a unit inverters are connected in series. The input terminal of the DC link of the first unit inverter is connected to the positive terminal of the DC power supply, and the output terminal of the DC link of the N*a unit inverter is connected to the negative terminal of the DC power supply. Furthermore, the m interfaces of the AC output terminal of the unit inverter are connected one-to-one with the m phase leads of the corresponding winding.

[0009] When the DC-link series-type fault-tolerant permanent magnet synchronous motor drive system is working, the output current of N*a unit inverters is controlled to make N*a windings generate the same electromagnetic torque, and at this time the DC voltage at the input terminal of each unit inverter is equal.

[0010] This invention also discloses a control method for the DC-link series-type fault-tolerant permanent magnet synchronous motor drive system, in case of a single power transistor open-circuit fault in a unit inverter:

[0011] Step A.1) Turn on the normal bridge arm power transistor of the faulty unit inverter to put the corresponding winding of the unit inverter into a short circuit state, so as to provide a current path for the normal unit inverter.

[0012] Step A.2) By adjusting the control strategy of the normal unit inverter, the average DC current of each unit inverter is kept constant, and the input voltage of the normal unit inverter is equal.

[0013] This invention also discloses a control method for the DC-link series-type fault-tolerant permanent magnet synchronous motor drive system, in case of a unit inverter experiencing a short-circuit fault:

[0014] The power transistors of both the faulty and normal arms of the unit inverter that has experienced a control failure are turned on, causing the corresponding winding of the unit inverter to be in a short-circuit state, thus providing a current path for the normal unit inverter and ensuring that the normal unit inverter continues to operate.

[0015] The present invention also discloses a control method for the DC link series-type fault-tolerant permanent magnet synchronous motor drive system, which reduces the current fluctuation of the DC link by controlling the phase shifting switches of each unit inverter.

[0016] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0017] This invention can ensure the normal operation of the drive unit when a single open circuit, short circuit fault, bridge arm shoot-through, or single open circuit or short circuit fault occurs in the inverter or winding. It has good fault tolerance and is suitable for applications with high reliability requirements, such as electric vehicle drive systems and aerospace electric propulsion systems. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the DC-link series-connected fault-tolerant drive system consisting of a single dual three-phase winding permanent magnet synchronous motor and two three-phase unit inverters according to the present invention.

[0019] Figure 2 This is a schematic diagram of the DC link series-connected fault-tolerant drive system structure, consisting of two dual three-phase winding permanent magnet synchronous motors and four three-phase unit inverters connected in series.

[0020] Figure 3 This is a schematic diagram of the DC-link series-connected fault-tolerant drive system consisting of a single three-phase winding permanent magnet synchronous motor and three three-phase unit inverters according to the present invention.

[0021] Figure 4 This is a schematic diagram of a four-drive-unit fault-tolerant drive system structure containing two parallel branches, each branch consisting of two drive units connected in series.

[0022] Figure 5 This is a control block diagram for the DC-link series-type fault-tolerant drive system consisting of a single dual-three-phase winding permanent magnet synchronous motor and two three-phase unit inverters, as described in this invention, during normal operation.

[0023] Figure 6 This is a schematic diagram of the control signals of the two unit inverter bridge arms when the DC link series fault-tolerant drive system consisting of a single dual three-phase winding permanent magnet synchronous motor and two three-phase unit inverters is operating normally and using phase shift control. Detailed Implementation

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings:

[0025] This invention can be implemented in many different forms and should not be considered limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully express the scope of the invention to those skilled in the art. In the drawings, components are enlarged for clarity.

[0026] This invention discloses a DC-link series-type fault-tolerant permanent magnet synchronous motor drive system, including a DC power supply, N permanent magnet synchronous motors, and N*a unit inverters, where N and a are both natural numbers greater than or equal to 1.

[0027] The permanent magnet synchronous motor has a winding number of a, and the winding unit has a phase number of m, where m is a natural number greater than or equal to 3; the inverter has a phase number of m; the N permanent magnet synchronous motors have a total of N*a windings, and the N*a unit inverters correspond one-to-one with the N*a windings;

[0028] The DC links of the N*a unit inverters are connected in series. The input terminal of the DC link of the first unit inverter is connected to the positive terminal of the DC power supply, and the output terminal of the DC link of the N*a unit inverter is connected to the negative terminal of the DC power supply. Furthermore, the m interfaces of the AC output terminal of the unit inverter are connected one-to-one with the m phase leads of the corresponding winding.

[0029] When the DC-link series-type fault-tolerant permanent magnet synchronous motor drive system is working, the output current of N*a unit inverters is controlled to make N*a windings generate the same electromagnetic torque, and at this time the DC voltage at the input terminal of each unit inverter is equal.

[0030] This invention also discloses a control method for the DC-link series-type fault-tolerant permanent magnet synchronous motor drive system, in case of a single power transistor open-circuit fault in a unit inverter:

[0031] Step A.1) Turn on the normal bridge arm power transistor of the faulty unit inverter to put the corresponding winding of the unit inverter into a short circuit state, so as to provide a current path for the normal unit inverter.

[0032] Step A.2) By adjusting the control strategy of the normal unit inverter, the average DC current of each unit inverter is kept constant, and the input voltage of the normal unit inverter is equal.

[0033] This invention also discloses a control method for the DC-link series-type fault-tolerant permanent magnet synchronous motor drive system, in case of a unit inverter experiencing a short-circuit fault:

[0034] The power transistors of both the faulty and normal arms of the unit inverter that has experienced a control failure are turned on, causing the corresponding winding of the unit inverter to be in a short-circuit state, thus providing a current path for the normal unit inverter and ensuring that the normal unit inverter continues to operate.

[0035] The present invention also discloses a control method for the DC link series-type fault-tolerant permanent magnet synchronous motor drive system, which reduces the current fluctuation of the DC link by controlling the phase shifting switches of each unit inverter.

[0036] like Figure 1 The diagram illustrates the application of this invention to a single dual three-phase motor. The key feature is that the dual three-phase permanent magnet synchronous motor in the drive system is three-phase, and the corresponding unit inverter is a two-level three-phase inverter. The DC buses of the two unit inverters are connected in series, and each inverter corresponds to a set of windings. The following are the fault-tolerant control strategies for normal operation and after an open-circuit or short-circuit fault:

[0037] Under normal operating conditions, the DC link current of each inverter is equal. By adjusting the reference current of each unit motor, the DC input voltage of each inverter is controlled to be equal, i.e., V. dc1 = V dc2 . Figure 5 This is the control block diagram for normal operation. Based on the traditional vector control strategy for single-winding inverters, it utilizes the error between the capacitor voltage and half the power supply voltage to adjust the output current of each inverter unit, achieving capacitor voltage balance. During normal operation, it can also employ... Figure 6The schematic diagram illustrates phase-shifting switch control, which means that when the switching cycle of the inverter power transistor is Ts, the switching cycles of the two inverters can be staggered by Ts / 2 to reduce DC link current fluctuations.

[0038] When a single power transistor experiences an open-circuit or short-circuit fault, such as power transistor T in unit inverter II... b3 When an open-circuit or short-circuit fault occurs, the non-faulty power transistor T of the inverter... b1 T b2 T b4 T b5 、and T b6 All are on. At this time, the DC input voltage of the faulty inverter is equal to 0, and the power transistor T... b1 T b4 With T b5 T b2 The parallel branch formed can provide a current path for unit inverter I, at which point the power supply voltage is borne by the normal unit inverter. In addition, T b1 T b2 T b4 T b5 、and T b6 Turning on the circuit can short-circuit the corresponding winding, thereby suppressing the torque pulsation of the motor.

[0039] When a shoot-through fault occurs in a bridge arm of a unit inverter, such as the power transistor T in unit inverter II... b1 and T b4 When a shoot-through fault occurs, the power transistor T on the non-faulty bridge arm of the inverter in this unit... b2 T b3 T b5 With T b6 All are on. At this time, the DC input voltage of the faulty inverter is equal to 0, and the power transistor T... b3 T b6 With T b5 T b2 The parallel branch formed can provide a current path for unit inverter I, at which time the power supply voltage is borne by the normal unit inverter; the winding corresponding to the faulty inverter is in a three-phase short circuit state, which can suppress the torque pulsation of the motor.

[0040] When a single-phase winding short-circuit fault occurs in the motor, such as when a short-circuit fault occurs in phase A2 winding, the power transistor T of the corresponding unit inverter will... b1 T b2 T b3 T b4 T b5 With T b6 All are on. At this time, the DC input voltage of the faulty inverter is equal to 0, and the power transistor T... b1 T b4 With T b3T b6 And T b5 T b2 The parallel branch formed can provide a current path for unit inverter I, at which time the power supply voltage is borne by the normal unit inverter; the winding corresponding to the faulty inverter is in a three-phase short circuit state, which can suppress the torque pulsation of the motor.

[0041] Figure 2 This invention is applied to multiple dual three-phase motors. Taking two motors as an example, under normal operating conditions, the DC link current of each inverter is equal. By adjusting the reference current of each unit motor, the DC input voltage of each inverter is controlled to be equal, i.e., V. dc1 = V dc2 = V dc3 = V dc4 .

[0042] When a single power transistor experiences an open-circuit or short-circuit fault, such as power transistor T in unit inverter II... b3 When an open-circuit or short-circuit fault occurs, the non-faulty power transistor T of the inverter... b1 T b2 T b4 T b5 、and T b6 All are on. At this time, the DC input voltage of the faulty inverter is equal to 0, and the power transistor T... b1 T b4 With T b5 T b2 The parallel branch provides current paths for unit inverters I, III, and IV. In this case, the power supply voltage is shared by the three normally functioning unit inverters and needs to be maintained by controlling the power of each unit inverter. Furthermore, T... b1 T b2 T b4 T b5 、and T b6 Turning on the circuit can short-circuit the corresponding unit motor windings, thereby suppressing the torque pulsation of the faulty unit motor.

[0043] When a shoot-through fault occurs in a bridge arm of a unit inverter, such as the power transistor T in unit inverter II... b1 and T b4 When a shoot-through fault occurs, the power transistor T on the non-faulty bridge arm of the inverter in this unit... b2 T b3 T b5 With T b6 All are on. At this time, the DC input voltage of the faulty inverter is equal to 0, and the power transistor T... b3 T b6 With T b5 T b2The parallel branch formed can provide current path for unit inverter I, unit inverter III, and unit inverter IV. At this time, the power supply voltage is shared by the three normal unit inverters. The unit motor windings corresponding to the faulty inverter are in a three-phase short circuit state, which can suppress the torque pulsation of the faulty unit motor.

[0044] When a single-phase winding short-circuit fault occurs in a unit motor, such as when a short-circuit fault occurs in the A2 phase winding of a dual three-phase motor I, the power transistor T of the corresponding unit inverter... b1 T b2 T b3 T b4 T b5 With T b6 All are on. At this time, the DC input voltage of the faulty inverter is equal to 0, and the power transistor T... b1 T b4 With T b3 T b6 And T b5 T b2 The parallel branch formed can provide current path for unit inverter I, unit inverter III, and unit inverter IV. At this time, the power supply voltage is shared by the three normal unit inverters. The unit motor windings corresponding to the faulty inverter are in a three-phase short circuit state, which can suppress the torque pulsation of the faulty unit motor. Figure 3 This is an example of the application of the present invention to a three-phase motor. The drive system consists of three inverters connected in series, with each inverter corresponding to a set of windings. The fault-tolerant control steps are the same as those for single and multiple dual three-phase motors.

[0045] Figure 4 The examples listed include a DC link series structure consisting of unit inverter I and unit inverter II, and a DC link series structure consisting of unit inverter III and unit inverter IV. The two series structures are connected in parallel and powered by Vdc.

[0046] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0047] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A DC-link series-type fault-tolerant permanent magnet synchronous motor drive system, characterized in that, It includes a DC power supply, N permanent magnet synchronous motors, and N*a unit inverters, where N and a are natural numbers greater than or equal to 1; The permanent magnet synchronous motor has a winding number of a, and the winding unit has a phase number of m, where m is a natural number greater than or equal to 3; the inverter has a phase number of m; the N permanent magnet synchronous motors have a total of N*a windings, and the N*a unit inverters correspond one-to-one with the N*a windings; The DC links of the N*a unit inverters are connected in series. The input terminal of the DC link of the first unit inverter is connected to the positive terminal of the DC power supply, and the output terminal of the DC link of the N*a unit inverter is connected to the negative terminal of the DC power supply. Furthermore, the m interfaces of the AC output terminal of the unit inverter are connected one-to-one with the m phase leads of its corresponding winding. When the DC-link series-type fault-tolerant permanent magnet synchronous motor drive system is working, the output current of N*a unit inverters is controlled to make N*a windings generate the same electromagnetic torque, and at this time the DC voltage at the input terminal of each unit inverter is equal.

2. The control method for the DC-link series-type fault-tolerant permanent magnet synchronous motor drive system according to claim 1, characterized in that, If a single power transistor open-circuit fault exists in a unit inverter: Step A.1) Turn on the normal bridge arm power transistor of the faulty unit inverter to put the corresponding winding of the unit inverter into a short circuit state, so as to provide a current path for the normal unit inverter. Step A.2) By adjusting the control strategy of the normal unit inverter, the average DC current of each unit inverter is kept constant, and the input voltage of the normal unit inverter is equal.

3. The control method for the DC-link series-type fault-tolerant permanent magnet synchronous motor drive system according to claim 1, characterized in that, If a unit inverter experiences a short-circuit fault: The power transistors of both the faulty and normal arms of the unit inverter that has experienced a control failure are turned on, causing the corresponding winding of the unit inverter to be in a short-circuit state, thus providing a current path for the normal unit inverter and ensuring that the normal unit inverter continues to operate.

4. The control method for the DC-link series-type fault-tolerant permanent magnet synchronous motor drive system according to claim 1, characterized in that, The current fluctuation in the DC link is reduced by controlling the phase shift switches of each inverter unit.

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