Fault-tolerant control device and method for permanent magnet synchronous motor

Abstract

The invention discloses a fault-tolerant control device and method for a permanent magnet synchronous motor, and belongs to the technical field of electric automobiles, and the device comprises a microcontroller, a Hall sensor current sampling unit, a fault-tolerant T-type three-level inverter, the permanent magnet synchronous motor (PMSM), and a relay group with nine groups of normally-closed contacts. The microcontroller is electrically connected with the relay set and the fault-tolerant T-type three-level inverter, and a path control signal output end of the microcontroller is electrically connected with a grid electrode of a switching tube of the fault-tolerant T-type three-level inverter; midpoints of bridge arms A, B and C of the fault-tolerant T-type three-level inverter are electrically connected with three phases of the PMSM, and the Hall sensor and the current sampling unit are electrically connected with input and output ports of the microcontroller. According to the device, the reliability and the stability of the system are improved, the production stagnation time and the loss caused by faults are effectively reduced, and important technical support and guarantee are provided for industrial application.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric vehicles, and in particular relates to a permanent magnet synchronous motor fault-tolerant control device and method. Background Art

[0002] In electric freight vehicles, fault-tolerant T-type three-level inverters play a key role, providing important support for their efficient and reliable operation. This inverter can not only effectively drive the permanent magnet synchronous motor of electric vehicles, but also has the ability to keep the system running in the face of inevitable faults, thereby minimizing parking time for maintenance and ensuring the continuity and efficiency of freight and logistics.

[0003] Electric freight trucks are usually required to withstand long-term and high-load operation, so their electric drive systems have strict requirements for high efficiency and durability. The fault-tolerant T-type three-level inverter can effectively cope with a variety of possible fault conditions through its special design advantages. For example, when a switch tube in the inverter fails, a traditional inverter may cause the entire system to shut down, while a fault-tolerant inverter can still work partially, maintaining at least part of the drive function by redistributing current and adjusting the control strategy. This capability greatly improves the reliability and stability of electric freight trucks in actual transportation.

[0004] In addition, the fault-tolerant inverter can also minimize the impact of faults on the overall system performance by quickly diagnosing faults and automatically switching to the appropriate fault-tolerant mode. This is especially important for electric freight trucks that require efficient and continuous transportation, because their operation not only affects the efficiency and cost of the enterprise, but is also directly related to customer service satisfaction and the quality of transportation tasks.

[0005] Compared with the traditional two-level inverter, the T-type three-level inverter has the advantages of low output voltage harmonic content, small voltage change rate, less electromagnetic interference, etc. Compared with the diode midpoint clamped three-level topology, the T-type inverter not only has fewer components, lower losses, lower output voltage harmonics, and higher efficiency, but also shows great development potential in the field of medium-voltage and high-power inverters.

[0006] Zhu Qinyue and Chen Zhiyuan et al. proposed that in motor drive systems, inverters often operate in harsh environments, and due to the high switching frequency of power devices, their life loss is fast, and overheating is particularly serious, which makes power devices prone to short circuit and open circuit faults. Zhang Bin and Liu Xin et al. pointed out that short circuit faults may cause excessive system current, thereby causing irreversible damage to the entire system. Therefore, it is urgent to detect, analyze and eliminate faults in a very short time. Chen Danjiang et al. proposed a fault-tolerant topology structure by adding redundant bridge arms and half-bridge switches as backup replacements after a phase bridge arm fails. Pang Xianzhe et al. connected fast fuses in series next to the power switching device to reduce the damage caused by short circuit faults to the system, and reconstructed the inverter topology to make it fault-tolerant. Kumar B and Peddapati S introduced a redundant unit with a resistor switching circuit, which increased the multi-phase fault tolerance function and improved the reliability of the converter. Literature proposed a fault diagnosis strategy based on the characteristics of open circuit faults, which can accurately locate the position of the faulty switch tube. Literature Zhang Jianzhong et al. proposed a method for fault diagnosis through space vector pulse width modulation and inverter output current. Li Shanshou, Tao Yong and others formulated a new modulation strategy by forming a virtual vector from the optimized basic vector. Sajitha M and Ramchand R introduced the application of traditional seven-segment SVPWM in multi-level inverters. Vu P, Van Nguyen T and Nguyen MD proposed two new pulse modes of two switching sequences based on the many difficulties in implementing SVPWM in multi-level inverters.

[0007] In view of the technical problems such as the T-type three-level inverter structure of the existing electric freight vehicle does not have the ability to convert short-circuit faults into open-circuit faults, the system does not have fault-tolerant working capabilities after a fault occurs, and there is no systematic and scientific fault-tolerant modulation strategy, it is urgent to find an electric freight vehicle motor control method and device to improve the fault-tolerant working capabilities of the electric freight vehicle system, so that the electric freight vehicle motor control system can effectively and stably transfer the inverter in the fault state to the fault-tolerant operating state until the fault is eliminated, thereby reducing the safety and economic impact of the switch tube failure on the working process. Summary of the invention

[0008] In order to overcome the shortcomings of the above-mentioned prior art, a permanent magnet synchronous motor fault-tolerant control device and method are proposed to solve the technical problems that the existing T-type three-level inverter structure of the electric freight car does not have the ability to convert short-circuit faults into open-circuit faults, the system does not have fault-tolerant working capabilities after a fault occurs, and there is no systematic and scientific fault-tolerant modulation strategy.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] One of the purposes of the present invention is to disclose a fault-tolerant control device for a permanent magnet synchronous motor, comprising: a microcontroller, a Hall sensor current sampling unit, a fault-tolerant T-type three-level inverter, a permanent magnet synchronous motor (PMSM), and a relay group with nine groups of normally closed contacts; the microcontroller is electrically connected to the relay group and the fault-tolerant T-type three-level inverter, a control signal output end of the microcontroller is electrically connected to the gate of a switch tube of the fault-tolerant T-type three-level inverter; the midpoints of bridge arms A, B and C of the fault-tolerant T-type three-level inverter are electrically connected to the three-phase of the PMSM, and the Hall sensor and the current sampling unit are electrically connected to the input and output ports of the microcontroller.

[0011] Another object of the present invention is to disclose a permanent magnet synchronous motor fault-tolerant control method, comprising the following steps:

[0012] S1. When the fault-tolerant T-type three-level inverter switch tube does not fail, the system maintains the original modulation strategy, the seven-segment SVPWM modulation strategy. The seven-segment SVPWM modulation strategy formulation steps are divided into the voltage zone vector V ref There are three steps: area judgment, basic vector time calculation, and time state allocation;

[0013] S2. Pre-classify the fault types of the fault-tolerant T-type three-level inverter switch tube after the fault occurs, and classify them into three types according to the number of fault phases, namely single-phase, two-phase, three-phase single-tube or multi-tube faults, and then formulate a feasibility table of fault-tolerant modulation strategies according to the fault types;

[0014] S3. For the fault types that meet the feasibility requirements of the fault-tolerant modulation strategy, a fault-tolerant modulation strategy is formulated in advance. The steps are the same as those for the seven-segment SVPWM modulation strategy. The difference is that the fault-tolerant modulation strategy needs to re-divide the area and then make regional judgments. Since the switch tube failure causes partial vector loss, the seven-segment SVPWM modulation strategy can no longer be used and should be adjusted to a five-segment SVPWM modulation strategy. Then, two steps, time calculation and time state allocation, are performed.

[0015] S4, after a short circuit or open circuit fault occurs in the fault-tolerant T-type three-level inverter switch tube, determine whether the current fault type meets the feasibility requirements of the fault-tolerant modulation strategy;

[0016] S5. For a fault type that meets the feasibility requirements of the fault-tolerant modulation strategy, the seven-segment SVPWM modulation strategy is switched to a fault-tolerant modulation strategy that meets the current fault type.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The strategy of the present invention can perform appropriate modulation responses to different types of faults according to the feasibility requirements of the fault-tolerant modulation strategy to ensure that the system can operate stably under the fault state until the fault is removed without affecting normal production. Specifically, when a fault is detected in the inverter or motor system, the system will accurately diagnose the fault type (such as open circuit or short circuit) and location (such as the fault of the switch tube inside the inverter). If the fault is fault-tolerant, the system will automatically switch to the corresponding fault-tolerant SVPWM modulation strategy. This strategy not only includes adjusting the inverter switch state to maintain the operation of the motor, but also involves readjustment of the current control link to ensure that the motor can still operate at the expected speed during the fault.

[0019] During this period, the speed loop control system will continue to monitor the actual speed and rotor position of the motor to ensure that the expected current and actual current are correctly generated after the Park inverse transformation. Through the adjustment of the PI regulator, the system can dynamically correct the current control to adapt to the operating conditions under the fault state. This approach ensures that even when a fault occurs, the system can maintain sufficient motor control accuracy to support normal production operation. Once the fault is removed or repaired, the system will automatically return to the normal SVPWM modulation strategy to ensure that the motor returns to the predetermined operating parameters and efficiency level.

[0020] Therefore, the fault-tolerant control strategy of the present invention not only improves the reliability and stability of the system, but also effectively reduces the production downtime and losses caused by faults, providing important technical support and guarantee for industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a topological diagram of a fault-tolerant T-type three-level inverter of the present invention;

[0022] Figure 2 It is a block diagram of a fault-tolerant control system of a permanent magnet synchronous motor based on a T-type three-level inverter of the present invention;

[0023] Figure 3 It is a simulation result diagram of the fault-tolerant T-type three-level inverter topology and fault-tolerant modulation strategy of the present invention;

[0024] Figure 4 The C-phase switch tube S of the present invention C2 , S C3 Fault test result diagram;

[0025] Figure 5 The BC two-phase switch tube S of the present invention B2 , S B3 , S C2 , S C3 Fault test result diagram;

[0026] Figure 6 The three-phase switch tube S of the present invention A2 , S A3 , S B2 , S B3 , S C2 , S C3 Fault test result diagram. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0029] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0030] The invention discloses a permanent magnet synchronous motor fault-tolerant control device, comprising: a microcontroller, a Hall sensor current sampling unit, a fault-tolerant T-type three-level inverter, a permanent magnet synchronous motor (PMSM), and a relay group with nine groups of normally closed contacts; the microcontroller is electrically connected to the relay group and the fault-tolerant T-type three-level inverter, a control signal output end of the microcontroller is electrically connected to the grid of a switch tube of the fault-tolerant T-type three-level inverter; the midpoints of bridge arms A, B and C of the fault-tolerant T-type three-level inverter are electrically connected to the three-phase of the PMSM, and the Hall sensor and the current sampling unit are electrically connected to the input and output ports of the microcontroller.

[0031] In order to cooperate with the proposed device, a permanent magnet synchronous motor fault-tolerant control method is proposed. The specific steps are as follows:

[0032] S1. When the fault-tolerant T-type three-level inverter switch tube does not fail, the system maintains the original modulation strategy, the seven-segment SVPWM modulation strategy. The seven-segment SVPWM modulation strategy formulation steps are divided into the voltage zone vector V ref There are three steps: area judgment, basic vector time calculation, and time state allocation;

[0033] S2. Pre-classify the fault types of the fault-tolerant T-type three-level inverter switch tube after the fault occurs, and classify them into three types according to the number of fault phases, namely single-phase, two-phase, three-phase single-tube or multi-tube faults, and then formulate a feasibility table of fault-tolerant modulation strategies according to the fault types;

[0034] S3. For the fault types that meet the feasibility requirements of the fault-tolerant modulation strategy, a fault-tolerant modulation strategy is formulated in advance. The steps are the same as those for the seven-segment SVPWM modulation strategy. The difference is that the fault-tolerant modulation strategy needs to re-divide the area and then make regional judgments. Since the switch tube failure causes partial vector loss, the seven-segment SVPWM modulation strategy can no longer be used and should be adjusted to a five-segment SVPWM modulation strategy. Then, two steps, time calculation and time state allocation, are performed.

[0035] S4, after a short circuit or open circuit fault occurs in the fault-tolerant T-type three-level inverter switch tube, determine whether the current fault type meets the feasibility requirements of the fault-tolerant modulation strategy;

[0036] S5. For a fault type that meets the feasibility requirements of the fault-tolerant modulation strategy, the seven-segment SVPWM modulation strategy is switched to a fault-tolerant modulation strategy that meets the current fault type.

[0037] In step S1, the seven-segment SVPWM modulation strategy formulation step is divided into three steps: area judgment, basic vector time calculation, and time state allocation. The specific process is as follows:

[0038] S1a, reference voltage region vector V ref Regional judgment: the entire voltage vector space is divided into six large sectors: I, II, III, IV, V, and VI. The sector number is N. Each large sector is 60 degrees, and each large sector is further divided into six small intervals: 1, 2, 3, 4, 5, and 6. The small interval number is n. The current reference voltage vector V is judged. ref At the specific sector position during rotation, obtain the specific values ​​of N and n;

[0039] S1b, voltage vectors are divided into large, medium, small and zero vectors. The large vector includes NPN, PPN, PNN, PNP, NNP, NPP. The medium vector includes OPN, PON, PNO, ONP, NOP, NPO. The small vector includes OPO, NON, PPO, OON, NOO, ONN, POP, ONO, OOP, NNO, OPP, NOO. The zero vector includes PPP, OOO, NNN.

[0040] S1c, basic vector time calculation, to simplify the calculation process, the II, III, IV, V, VI large sectors are normalized to the I large sector, and only the basic vector time of the I large sector needs to be calculated. Before calculating the basic vector time of the I large sector, it is necessary to first determine the basic vector order of each small interval of the I large sector. The basic vector order of interval I(1) is ONN-OON-OOO-POO-OOO-OON-ONN, and the basic vector order of interval I(2) is OON-OOOO-POO-PPO -POO-OOO-OON, the basic vector order of interval I(3) is ONN-OON-PON-POO-PON-OON-ONN, the basic vector order of interval I(4) is OON-PON-POO-PPO-POO-PON-OON, the basic vector order of interval I(5) is ONN-PNN-PON-POO-PON-PNN-ONN, the basic vector order of interval I(6) is OON-PON-PPN-PPO-PPN-PON-OON;

[0041] In step S1d and step S1c, the vectors of each sector are recorded as V1, V2, and V3 in order. Since the seven-segment SVPWM modulation strategy vectors are symmetrical about the center, and the fourth vector and the first vector are redundant vectors, that is, the vectors have different names but the same functions, there are actually only three different basic vectors V1, V2, and V3 in a vector sequence. The action time of each vector is calculated according to the volt-second balance principle.

[0042] I(1) interval basic vector action time:

[0043]

[0044] I(2) interval basic vector action time:

[0045]

[0046] I(3) basic vector action time in interval:

[0047]

[0048] I(4) basic vector action time in interval:

[0049]

[0050] I(5) basic vector action time in interval:

[0051]

[0052] I(6) basic vector action time in interval:

[0053]

[0054] in:

[0055]

[0056] m is the modulation ratio, U ref is the reference voltage, U dc is the DC bus voltage;

[0057] S1e, based on the vector sequence between small cells in large sector I, after fixing the basic vector sequence, other large sectors allocate the time state to reduce the time calculation of the basic vector, divide the large sector into odd and even sectors, and convert the basic vector action time calculated in S1d into the switch tube switching time points Ta, Tb, Tc, where:

[0058] When the large sector is an odd sector, that is, N = 1, 3, 5,

[0059]

[0060] When the large sector is an odd sector, that is, N = 2, 4, or 6,

[0061]

[0062] The double modulation wave single carrier method is used to generate the pulse sequence. Each phase of the T-type three-level inverter contains 4 switch tubes, of which Sx1 and Sx3 are complementary, and Sx2 and Sx4 are complementary. The carrier is selected by the middle alignment upward counting method, and the height is taken as Ts / 2. When the carrier is greater than the modulation wave, the high level is valid. Since the carrier adopts the central symmetrical counting form, the modulation wave height is Ts / 2, so the modulation wave height is also the time point when the switch tube state is switched (T a1 , T a2 , T b1 , T b2 , T c1 , T c2 ), the height assigned by the modulation wave and the switching point time of the switch tube are equivalent to each other. The modulation wave height is summarized in the following table:

[0063]

[0064]

[0065]

[0066] In step S2, the fault type of the fault-tolerant T-type three-level inverter switch tube after the fault occurs is pre-classified, where S x1 , S x4 For the outer tube, S x2 , S x3 For the inner pipe (x = A, B, C), formulate a feasibility table of fault-tolerant modulation strategy:

[0067]

[0068] In step S3, the fault-tolerant modulation strategy is a five-segment SVPWM fault-tolerant modulation strategy, and the formulation steps are also divided into three steps: area judgment, basic vector time calculation, and time state allocation. The specific process is as follows:

[0069] Regional judgment:

[0070] S3a, due to the switch failure, the vector is lost, in the reference voltage region vector V ref When judging the area, the entire voltage vector space is divided into six large sectors: I, II, III, IV, V, and VI. The sector number is N. Each large sector is 60 degrees. The large sector division method is consistent with the seven-segment SVPWM. The division between small sectors varies according to the fault type. Single-phase S C2 , S C3 For example, when a fault occurs, the large sectors I, II, IV, and V are divided into two small sectors 1 and 2 based on the bisector of each sector angle. The small sector number is n. The large sectors III and VI remain intact sectors and are no longer divided. The two-phase S B2 , S C2 For example, the large sectors II and V are divided into two small sectors 1 and 2 based on the bisector of each sector angle. The small sector number is n. The large sectors I, III, IV, and VI remain as complete sectors and are no longer divided. The three-phase S A2 , S B2 , S C2 Taking fault as an example, the large sectors I, II, III, IV, V, and VI are kept as complete sectors and no longer divided into small intervals. The current reference voltage vector V ref At the specific sector position during rotation, obtain the specific values ​​of N and n;

[0071] S3b, due to the different vector loss caused by the switch tube failure, it is necessary to re-count the vector according to the fault type and then classify it. C2 , S C3For example, the large vector includes NPN, PPN, PNN, PNP, NNP, NPP, the medium vector includes OPN, PON, ONP, NOP, the small vector includes NON, OON, ONN, POP, OOP, OPP, the zero vector includes PPP, NNN, and the two-phase S B2 , S C2 For example, the large vector includes NPN, PPN, PNN, PNP, NNP, and NPP, the medium vector includes OPN and ONP, the small vector includes ONN and OPP, and the zero vector includes PPP and NNN. A2 , S B2 , S C2 Taking fault as an example, the large vector includes NPN, PPN, PNN, PNP, NNP, NPP, no middle vector, no small vector, and the zero vector includes PPP and NNN;

[0072] Basic vector time calculations:

[0073] S3c, single-phase S C2 , S C3 Basic vector sequence at fault:

[0074]

[0075]

[0076] Two-phase S B2 , S C2 Basic vector sequence at fault:

[0077] Sector Number Vector Order I NNN-PNN-PPN-PNN-NNN II(1) NNN-NPN-OPN-NPN-NNN II(2) NNN-NPN-OPN-NPN-NNN III NNN-NPN-NPP-NPN-NNN IV NNN-NNP-NPP-NNP-NNN V(1) NNN-NNP-ONP-NNP-NNN V(2) NNN-ONP-PNP-ONP-NNN VI NNN-PNN-PNP-PNN-NNN

[0078] Three-phase S A2 , S B2 , S C2 Basic vector sequence at fault:

[0079] Sector Number Vector Order I NNN-PNN-PPN-PNN-NNN II NNN-NPN-PPN-NPN-NNN III NNN-NPN-NPP-NPN-NNN IV NNP-NPP-PPP-NPP-NNN V NNP-PNP-PPP-PNP-NNP VI PNN-PNP-PPP-PNP-PNN

[0080] In step S3d and step S3c, the vectors of each sector are recorded as V1, V2, and V3 in order. Since the five-segment SVPWM modulation strategy vector is symmetrical about the center, there are actually only three different basic vectors V1, V2, and V3 in a vector sequence. The action time of each vector is calculated according to the volt-second balance principle. To simplify the basic vector calculation time process, the single-phase S C2 , S C3 When a fault occurs, the II, IV, and V large sectors are normalized to the I large sector. The vector action time of the III large sector is calculated separately. The VI large sector is normalized to the III large sector. Therefore, only the basic vector action time of the I and III large sectors needs to be calculated.B2 , S C2 When a fault occurs, the IV large sector is normalized to the I large sector, the V large sector is normalized to the II large sector, and the VI large sector is normalized to the III large sector. Therefore, it is only necessary to calculate the basic vector action time of the I, II, and III large sectors. The three-phase S A2 , S B2 , S C2 When a fault occurs, the two-level SVPWM modulation strategy is used to calculate the basic vector action time of the six large sectors, and the calculation process is simplified by normalizing them to the first large sector.

[0081] Single-phase S C2 , S C3 In case of failure:

[0082] I(1) interval basic vector action time:

[0083]

[0084] I(2) interval basic vector action time:

[0085]

[0086] III interval basic vector action time:

[0087]

[0088] in:

[0089]

[0090] m is the modulation ratio, U ref is the reference voltage, U dc is the DC bus voltage; two-phase S B2 , S C2 In case of failure:

[0091] I sector basic vector action time:

[0092]

[0093] II(1) Interval basic vector action time:

[0094]

[0095] II(2) Interval basic vector action time:

[0096]

[0097] III sector basic vector action time:

[0098]

[0099] in:

[0100]

[0101] m is the modulation ratio, U ref is the reference voltage, U dc is the DC bus voltage; three-phase S A2 , S B2 , S C2 In case of failure:

[0102] I sector basic vector action time:

[0103]

[0104] in:

[0105]

[0106] m is the modulation ratio, U ref is the reference voltage, U dc is the DC bus voltage;

[0107] Time state allocation:

[0108] Single-phase S C2 , S C3 In case of failure:

[0109] The basic vector action time is summarized as follows:

[0110] Sector Number Vector action time I(1) <![CDATA[T 11 / 2-T 12 / 2-T 13 -T 12 / 2-T 11 / 2]]> I(2) <![CDATA[T 21 / 2-T 22 / 2-T 23 -T 22 / 2-T 21 / 2]]> II(1) <![CDATA[T 11 / 2-T 13 / 2-T 12 -T 13 / 2-T 11 / 2]]> II(2) <![CDATA[T 21 / 2-T 23 / 2-T 22 -T 23 / 2-T 21 / 2]]> III <![CDATA[T 31 / 2-T 32 / 2-T 33 -T 32 / 2-T 31 / 2]]> IV(1) <![CDATA[T 11 / 2-T 13 / 2-T 12 -T 13 / 2-T 11 / 2 <!-- 11 -->]]> IV(2) <![CDATA[T 21 / 2-T 23 / 2-T 22 -T 23 / 2-T 21 / 2]]> V(1) <![CDATA[T 11 / 2-T 12 / 2-T 13 -T 12 / 2-T 11 / 2]]> V(2) <![CDATA[T 21 / 2-T 22 / 2-T 23 -T 22 / 2-T 21 / 2]]> VI <![CDATA[T 31 / 2-T 33 / 2-T 32 -T 33 / 2-T 31 / 2]]>

[0111] The modulation wave height is summarized in the following table:

[0112] in:

[0113]

[0114] T1, T2, T3 are the action times corresponding to the basic vectors V1, V2, V3 in each sector interval.

[0115]

[0116]

[0117] Two-phase S B2 , S C2 In case of failure:

[0118] The basic vector action time is summarized as follows:

[0119] Sector Number Vector action time I <![CDATA[T 11 / 2-T 12 / 2-T 13 -T 12 / 2-T 11 / 2]]> II(1) <![CDATA[T 21 / 2-T 22 / 2-T 23 -T 22 / 2-T 21 / 2]]> II(2) <![CDATA[T 21 / 2-T 22 / 2-T 23 -T 22 / 2-T 21 / 2]]> III <![CDATA[T 31 / 2-T 32 / 2-T 33 -T 32 / 2-T 31 / 2]]> IV <![CDATA[T 11 / 2-T 13 / 2-T 12 -T 13 / 2-T 11 / 2]]> V(1) <![CDATA[T 21 / 2-T 23 / 2-T 22 -T 23 / 2-T 21 / 2]]> V(2) <![CDATA[T 21 / 2-T 23 / 2-T 22 -T 22 / 2-T 21 / 2 <!-- 12 -->]]> VI <![CDATA[T 31 / 2-T 33 / 2-T 32 -T 33 / 2-T 31 / 2]]>

[0120] The modulation wave height is summarized in the following table:

[0121] in:

[0122]

[0123] T1, T2, T3 are the action times corresponding to the basic vectors V1, V2, V3 in each sector interval

[0124]

[0125]

[0126] Three-phase S A2 , S B2 , S C2 When a fault occurs;

[0127] The basic vector action time is summarized as follows:

[0128] Sector Number Vector action time I <![CDATA[T 11 / 2-T 12 / 2-T 13 -T 12 / 2-T 11 / 2]]> II <![CDATA[T 11 / 2-T 13 / 2-T 12 -T 13 / 2-T 11 / 2]]> III <![CDATA[T 11 / 2-T 12 / 2-T 13 -T 12 / 2-T 11 / 2]]> IV <![CDATA[T 12 / 2-T 13 / 2-T 11 -T 13 / 2-T 12 / 2]]> V <![CDATA[T 13 / 2-T 12 / 2-T 11 -T 12 / 2-T 13 / 2]]> VI <![CDATA[T 12 / 2-T 13 / 2-T 11 -T 13 / 2-T 12 / 2]]>

[0129] The modulation wave height is summarized in the following table:

[0130] in:

[0131]

[0132] T1, T2, T3 are the action times corresponding to the basic vectors V1, V2, V3 in each sector interval

[0133]

[0134]

[0135] See also Figure 1 It is a topological diagram of a fault-tolerant T-type three-level inverter of the present invention;

[0136] The fault-tolerant T-type three-level inverter topology is as follows: Figure 1 As shown in the figure, each phase of this topology consists of 4 power switches with anti-parallel diodes, 3 fuses, and 3 normally closed contacts of relays, among which S x1 , S x4 For the outer tube, S x2 , S x3 is the inner tube (x=A, B, C). x1 and S x2 When turned on, the inverter output voltage is U dc / 2, defined as P state; when S x2 and S x3 When the inverter is turned on, the output voltage is 0, which is defined as the O state; when S x3 and Sx4 When turned on, the inverter output voltage is -U dc / 2, defined as N state. When a short circuit occurs in a phase switch tube, the control unit determines the fault position of the switch tube based on the current sampling information, and controls the normally closed contact of the relay at the fault position to open, thereby converting the short circuit fault into an open circuit fault. In order to prevent the normally closed contact of the relay from failing to disconnect in time, causing more serious damage to the system, the fuse can also be disconnected in time when a short circuit occurs, thereby uniformly converting the short circuit fault into an open circuit fault.

[0137] See also Figure 2 It is a block diagram of a fault-tolerant control system of a permanent magnet synchronous motor based on a T-type three-level inverter of the present invention;

[0138] The fault-tolerant control system of T-type three-level inverter permanent magnet synchronous motor adopts the vector control mode of id=0. First, according to the three-phase current i abc Determine whether the current inverter switch tube is faulty. If no fault occurs, continue to use the traditional SVPWM modulation strategy; if it is determined that the switch tube is faulty, it is necessary to further determine the fault type and location. If it is an open circuit fault, the relay does not operate; if it is a short circuit fault, the relay at the corresponding position operates to cut off the short-circuited switch tube to prevent the situation from worsening. Evaluate the feasibility of the fault-tolerant modulation strategy according to the fault type. If the fault-tolerant modulation strategy is feasible, switch the original modulation strategy to the fault-tolerant SVPWM modulation strategy of the current fault type to ensure that the system continues to operate in a fault-tolerant state.

[0139] See also Figure 3 It is a simulation result diagram of the fault-tolerant T-type inverter topology and fault-tolerant modulation strategy of the present invention;

[0140] Figure 3 (a) is the C phase switch tube S C2 , S C3 Fault, the fault lasts for 0.1s, and it switches to the single-phase fault-tolerant modulation strategy. After the switch tube fails, the three-phase current, speed, and line voltage are distorted. When the single-phase fault-tolerant modulation strategy takes effect, the three-phase current and speed return to a stable state, and the three line voltages change from the original three-level state to a five-level state. The line voltage Vbc is omitted in the figure.

[0141] Figure 3 (b) is the BC phase switch tube S B2 , S B3 , S C2 , S C3Fault, the fault lasts for 0.1s, and the two-phase fault-tolerant modulation strategy is switched. The simulation results are shown in Figure 10. The change trends of the three-phase current and speed are similar to those in Figure 9. The three line voltages also recover from the distorted state to the stable state. The line voltage Vbc presents a three-level structure, and the other two line voltages are five-level structures. The line voltage Vac is omitted in the figure.

[0142] Figure 3 (c) is the ABC phase switch tube S A2 , S A3 , S B2 , S B3 , S C2 , S C3 The fault lasts for 0.1s and the three-phase fault-tolerant modulation strategy is switched. The three-phase current, speed and line voltage are quickly restored to a stable state. Since the ABC phases have lost the ability to output the midpoint O level state, each phase is actually degraded to a two-level output capability. However, the three-level modulation and wave generation strategy is still used, except that S x1 , S x2 The driving signal is the same as S x3 , S x4 The driving signal of the switch tube S x1 , S x2 As a switch tube, the switch tube S x3 , S x4 As a switch tube, the two-level concept is applied to the three-level fault-tolerant working state. Therefore, at this time, the three line voltages all present a three-level structure, and the line voltage Vbc is omitted in the figure.

[0143] See also Figure 4 This is a diagram showing the results of the C-phase switch tube SC2 and SC3 fault test of the present invention; wherein, Figure 4 (a) is the speed and three-phase current, Figure 4 (b) is the line voltage / torque between BC, Figure 4 (c) is the AC line voltage / torque. This fault type complies with the single-phase fault-tolerant modulation strategy. Under the condition of constant speed and load torque, the speed, three-phase current, line voltage and output torque characteristics of each stage are measured as follows: Figure 4 As shown. In closed-loop steady-state operation, the speed and output torque can follow the given speed and load torque, the three-phase current has obvious sinusoidal characteristics, and the line voltage is a three-level structure. After a fault occurs, the speed, three-phase current, line voltage and output torque all fluctuate significantly. When the single-phase fault-tolerant modulation strategy takes effect, the speed, three-phase current, line voltage and output torque all return to a steady state, and in order to follow the given speed, the line voltage now presents a five-level structure.

[0144] See also Figure 5 The BC two-phase switch tube S of the present invention B2 , SB3 , S C2 , S C3 Fault test result diagram; among them, Figure 5 (a) is the speed and three-phase current, Figure 5 (b) is the line voltage / torque between BC, Figure 5 (c) is the AC line voltage / torque. This fault type complies with the two-phase fault-tolerant modulation strategy. After the two-phase fault-tolerant modulation strategy takes effect, the three-phase current, speed, line voltage, and output torque all return to a stable state. After steady state, the BC line voltage presents a three-level structure, and the AC and AB line voltages present a five-level structure after steady state.

[0145] See also Figure 6 The three-phase switch tube S of the present invention A2 , S A3 , S B2 , S B3 , S C2 , S C3 Fault test result diagram; among them, Figure 6 (a) is the speed and three-phase current, Figure 6 (b) is the AC line voltage / torque. After the three-phase fault-tolerant modulation strategy takes effect, the three-phase current, speed, line voltage and output torque are restored to normal, and the three phases ABC lose the O level state. Therefore, the three line voltages all present a three-level structure after the fault-tolerant modulation strategy takes effect.

[0146] Comparing the above theoretical and simulation results, it is found that the two are consistent in the laws of motion change and strictly abide by the conclusions of theoretical analysis.

[0147] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A permanent magnet synchronous motor fault-tolerant control device, characterized in that: The device comprises: a microcontroller, a Hall sensor current sampling unit, a fault-tolerant T-type three-level inverter, a permanent magnet synchronous motor (PMSM), and a relay group with nine groups of normally closed contacts; the microcontroller is electrically connected to the relay group and the fault-tolerant T-type three-level inverter, the control signal output end of the microcontroller is electrically connected to the grid of the switch tube of the fault-tolerant T-type three-level inverter; the midpoints of the bridge arms A, B and C of the fault-tolerant T-type three-level inverter are electrically connected to the three phases of the PMSM, and the Hall sensor and the current sampling unit are electrically connected to the input and output ports of the microcontroller.

2. A permanent magnet synchronous motor fault-tolerant control method, characterized in that: The following steps are involved: S1. When the fault-tolerant T-type three-level inverter switch tube does not fail, the system maintains the original modulation strategy, the seven-segment SVPWM modulation strategy. The seven-segment SVPWM modulation strategy formulation steps are divided into the voltage zone vector V ref There are three steps: area judgment, basic vector time calculation, and time state allocation; S2. Pre-classify the fault types of the fault-tolerant T-type three-level inverter switch tube after the fault occurs, and classify them into three types according to the number of fault phases, namely single-phase, two-phase, three-phase single-tube or multi-tube faults, and then formulate a feasibility table of fault-tolerant modulation strategies according to the fault types; S3. For the fault types that meet the feasibility requirements of the fault-tolerant modulation strategy, a fault-tolerant modulation strategy is formulated in advance. The steps are the same as those for the seven-segment SVPWM modulation strategy. The difference is that the fault-tolerant modulation strategy needs to re-divide the area and then make regional judgments. Since the switch tube failure causes partial vector loss, the seven-segment SVPWM modulation strategy can no longer be used and should be adjusted to a five-segment SVPWM modulation strategy. Then, two steps, time calculation and time state allocation, are performed. S4, after a short circuit or open circuit fault occurs in the fault-tolerant T-type three-level inverter switch tube, determine whether the current fault type meets the feasibility requirements of the fault-tolerant modulation strategy; S5. For a fault type that meets the feasibility requirements of the fault-tolerant modulation strategy, the seven-segment SVPWM modulation strategy is switched to a fault-tolerant modulation strategy that meets the current fault type.

3. A permanent magnet synchronous motor fault-tolerant control method according to claim 2, characterized in that: In step S1, the seven-segment SVPWM modulation strategy formulation step is divided into three steps: area judgment, basic vector time calculation, and time state allocation. The specific process is as follows: S1a, reference voltage region vector V ref Regional judgment: the entire voltage vector space is divided into six large sectors: I, II, III, IV, V, and VI. The sector number is N. Each large sector is 60 degrees, and each large sector is further divided into six small intervals: 1, 2, 3, 4, 5, and 6. The small interval number is n. The current reference voltage vector V is judged. ref At the specific sector position during rotation, obtain the specific values ​​of N and n; S1b, voltage vectors are divided into large, medium, small and zero vectors. The large vector includes NPN, PPN, PNN, PNP, NNP, NPP. The medium vector includes OPN, PON, PNO, ONP, NOP, NPO. The small vector includes OPO, NON, PPO, OON, NOO, ONN, POP, ONO, OOP, NNO, OPP, NOO. The zero vector includes PPP, OOO, NNN. S1c, basic vector time calculation, to simplify the calculation process, the II, III, IV, V, VI large sectors are normalized to the I large sector, and only the basic vector time of the I large sector needs to be calculated. Before calculating the basic vector time of the I large sector, it is necessary to first determine the basic vector order of each small interval of the I large sector. The basic vector order of interval I(1) is ONN-OON-OOO-POO-OOO-OON-ONN, and the basic vector order of interval I(2) is OON-OOOO-POO-PPO -POO-OOO-OON, the basic vector order of interval I(3) is ONN-OON-PON-POO-PON-OON-ONN, the basic vector order of interval I(4) is OON-PON-POO-PPO-POO-PON-OON, the basic vector order of interval I(5) is ONN-PNN-PON-POO-PON-PNN-ONN, the basic vector order of interval I(6) is OON-PON-PPN-PPO-PPN-PON-OON; In step S1d and step S1c, the vectors of each sector are recorded as V1, V2, and V3 in order. Since the seven-segment SVPWM modulation strategy vectors are symmetrical about the center, and the fourth vector and the first vector are redundant vectors, that is, the vectors have different names but the same functions, there are actually only three different basic vectors V1, V2, and V3 in a vector sequence. The action time of each vector is calculated according to the volt-second balance principle. I(1) interval basic vector action time: I(2) interval basic vector action time: I(3) basic vector action time in interval: I(4) basic vector action time in interval: I(5) basic vector action time in interval: I(6) basic vector action time in interval: in: m is the modulation ratio, U ref is the reference voltage, U dc is the DC bus voltage; S1e, based on the vector sequence between small cells in large sector I, after fixing the basic vector sequence, other large sectors allocate the time state to reduce the time calculation of the basic vector, divide the large sector into odd and even sectors, and convert the basic vector action time calculated in S1d into the switch tube switching time points Ta, Tb, Tc, where: When the large sector is an odd sector, that is, N = 1, 3, 5, When the large sector is an odd sector, that is, N = 2, 4, or 6, The double modulation wave single carrier method is used to generate the pulse sequence. Each phase of the T-type three-level inverter contains 4 switch tubes, among which Sx1 and Sx3 are complementary, and Sx2 and Sx4 are complementary. The carrier is selected by the middle alignment upward counting method, and the height is taken as Ts / 2. When the carrier is greater than the modulation wave, the high level is valid. Since the carrier adopts the central symmetrical counting form, the modulation wave height is Ts / 2, so the modulation wave height is also the time point when the switch tube state is switched (T a1 , T a2 , T b1 , T b2 , T c1 , T c2 ), the height assigned by the modulation wave and the switching point time of the switch tube are equivalent to each other. The modulation wave height is summarized in the following table:

4. A permanent magnet synchronous motor fault-tolerant control method according to claim 2, characterized in that: In step S2, the fault type of the fault-tolerant T-type three-level inverter switch tube after the fault occurs is pre-classified, where S x1 , S x4 For the outer tube, S x2 , S x3 For the inner pipe (x = A, B, C), formulate a feasibility table of fault-tolerant modulation strategy:

5. A permanent magnet synchronous motor fault-tolerant control method according to claim 2, characterized in that: In step S3, the fault-tolerant modulation strategy is a five-segment SVPWM fault-tolerant modulation strategy, and the formulation steps are also divided into three steps: area judgment, basic vector time calculation, and time state allocation. The specific process is as follows: Regional judgment: S3a, due to the switch failure, the vector is lost, in the reference voltage region vector V ref When judging the area, the entire voltage vector space is divided into six large sectors: I, II, III, IV, V, and VI. The sector number is N. Each large sector is 60 degrees. The large sector division method is consistent with the seven-segment SVPWM. The division between small sectors varies according to the fault type. Single-phase S C2 , S C3 For example, when a fault occurs, the large sectors I, II, IV, and V are divided into two small sectors 1 and 2 based on the bisector of each sector angle. The small sector number is n. The large sectors III and VI remain intact sectors and are no longer divided. The two-phase S B2 , S C2 For example, the large sectors II and V are divided into two small sectors 1 and 2 based on the bisector of each sector angle. The small sector number is n. The large sectors I, III, IV, and VI remain as complete sectors and are no longer divided. The three-phase S A2 , S B2 , S C2 Taking fault as an example, the large sectors I, II, III, IV, V, and VI are kept as complete sectors and no longer divided into small intervals. The current reference voltage vector V ref At the specific sector position during rotation, obtain the specific values ​​of N and n; S3b, due to the different vector loss caused by the switch tube failure, it is necessary to re-count the vector according to the fault type and then classify it. C2 , S C3 For example, the large vector includes NPN, PPN, PNN, PNP, NNP, NPP, the medium vector includes OPN, PON, ONP, NOP, the small vector includes NON, OON, ONN, POP, OOP, OPP, the zero vector includes PPP, NNN, and the two-phase S B2 , S C2 For example, the large vector includes NPN, PPN, PNN, PNP, NNP, and NPP, the medium vector includes OPN and ONP, the small vector includes ONN and OPP, and the zero vector includes PPP and NNN. A2 , S B2 , S C2 Taking fault as an example, the large vector includes NPN, PPN, PNN, PNP, NNP, NPP, there is no middle vector, no small vector, and the zero vector includes PPP and NNN.

6. A permanent magnet synchronous motor fault-tolerant control method according to claim 2, characterized in that: Basic vector time calculations: S3c, single-phase S C2 , S C3 Basic vector sequence at fault: Two-phase S B2 , S C2 Basic vector sequence at fault: Three-phase S A2 , S B2 , S C2 Basic vector sequence at fault: In step S3d and step S3c, the vectors of each sector are recorded as V1, V2, and V3 in order. Since the five-segment SVPWM modulation strategy vector is symmetrical about the center, there are actually only three different basic vectors V1, V2, and V3 in a vector sequence. The action time of each vector is calculated according to the volt-second balance principle. To simplify the basic vector calculation time process, the single-phase S C2 , S C3 When a fault occurs, the II, IV, and V large sectors are normalized to the I large sector. The vector action time of the III large sector is calculated separately. The VI large sector is normalized to the III large sector. Therefore, only the basic vector action time of the I and III large sectors needs to be calculated. B2 , S C2 When a fault occurs, the IV large sector is normalized to the I large sector, the V large sector is normalized to the II large sector, and the VI large sector is normalized to the III large sector. Therefore, it is only necessary to calculate the basic vector action time of the I, II, and III large sectors. The three-phase S A2 , S B2 , S C2 When a fault occurs, the two-level SVPWM modulation strategy is used to calculate the basic vector action time of the six large sectors, and the calculation process is simplified by normalizing them to the first large sector. Single-phase S C2 , S C3 In case of failure: I(1) interval basic vector action time: I(2) interval basic vector action time: III interval basic vector action time: in: m is the modulation ratio, U ref is the reference voltage, U dc is the DC bus voltage; two-phase S B2 , S C2 In case of failure: I sector basic vector action time: II(1) Interval basic vector action time: II(2) Interval basic vector action time: III sector basic vector action time: in: m is the modulation ratio, U ref is the reference voltage, U dc is the DC bus voltage; three-phase S A2 , S B2 , S C2 In case of failure: I sector basic vector action time: in: m is the modulation ratio, U ref is the reference voltage, U dc is the DC bus voltage.

7. A permanent magnet synchronous motor fault-tolerant control method according to claim 2, characterized in that: Time state allocation: Single-phase S C2 , S C3 In case of failure: The basic vector action time is summarized as follows: The modulation wave height is summarized in the following table: in: T1, T2, T3 are the action times corresponding to the basic vectors V1, V2, V3 in each sector interval; Two-phase S B2 , S C2 In case of failure: The basic vector action time is summarized as follows: The modulation wave height is summarized in the following table: in: T1, T2, T3 are the action times corresponding to the basic vectors V1, V2, V3 in each sector interval; Three-phase S A2 , S B2 , S C2 In case of failure: The basic vector action time is summarized as follows: The modulation wave height is summarized in the following table: in: T1, T2, T3 are the action times corresponding to the basic vectors V1, V2, V3 in each sector interval;

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