Series-wound motor winding phase sequence switching topology system, modulation method and inverter

Abstract

The present invention belongs to, but is not limited to, the technical field of AC motors and drive control, and discloses a series-wound motor winding phase sequence switching topology system, modulation method, and inverter, including a first bridge arm L 1, a second bridge arm L 2, a third bridge arm L 3, a fourth bridge arm L 4, and bipolar diodes TR 1, TR 2, TR 3, and TR 4. By turning on or off the four bipolar diodes, the phase sequence of the series-wound motor can be changed. Then, by switching the corresponding modulation strategy, the three-phase series-wound motor can use the torque output topology structure at low speed and heavy load, and the speed output topology structure at high speed and light load. With the help of the switching of the series-wound motor topology structure, the present invention can optimize the working range and efficiency of the series-wound motor to adapt to different operating conditions, and effectively expand the torque-speed operating range of the three-phase series-wound motor.

Description

Technical Field

[0001] The present invention belongs to but is not limited to the field of AC motor and drive control technology, and in particular relates to a series winding motor winding phase sequence switching topology system, a modulation method and an inverter. Background Art

[0002] The motor drive topology widely used in industry at present is the three-phase star connection topology, which has the advantages of high stability and low loss. However, this topology can only output 57.7% bus voltage utilization in the linear modulation area, which seriously limits the motor speed operating range. In addition, the star connection topology has only two current degrees of freedom and its fault tolerance is poor. The series winding motor topology can achieve 100% bus voltage utilization by connecting the beginning and end of each phase winding sequence in series, effectively expanding the motor speed operating range. In addition, this topology can provide three current control degrees of freedom and has higher fault tolerance.

[0003] However, when using this topology drive, due to the middle bridge arm of the inverter L 2. L 3 bears greater current stress, which limits the overall torque output capacity of the drive system. In order to reduce the bridge arm stress and increase the torque output, you can change B Phase winding sequence, B Phase winding input terminal connected to bridge arm L 3. B Phase winding output terminal connected to bridge arm L 2. At this time, the middle bridge arm L 2 and L 3 will decrease and be equal to the current stress of the bridge arms on both sides, so its torque output capacity can be improved. However, this topology reduces the motor bus voltage utilization rate and limits its high speed application.

[0004] In summary, a single output mode cannot maximize the use of the working range of the series-wound motor. In addition, the existing technology does not propose a suitable modulation strategy to adapt to different output modes of the series-wound motor. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a series-winding motor winding phase sequence switching topology system, a modulation method and an inverter.

[0006] The present invention is implemented as follows: a series winding motor winding phase sequence switching topology system is composed of four bridge arms, namely bridge arm L 1. L 2. L 3. L 4, and four bipolar diodes: TR 1. TR 2.TR 3. TR 4; Each bridge arm consists of an upper and a lower power switching device; The DC bus voltage source is connected to the upper node of each upper power switching device, while the power ground is connected to the lower node of the lower power switching device;

[0007] The three-phase series-wound motor consists of A , B , and three-phase stator windings of phase C. A The input end of the phase winding is connected to bridge arm L 1, A and the output end of the phase winding is connected to bridge arm L 2; B The input end of the phase winding is connected to bridge arm L 2, B and the output end of the phase winding is connected to bridge arm L 3; The bipolar diodes TR 1, TR 3 are connected to B the input end of the phase winding, TR 2, TR 4 are connected to B the output end of the phase winding; C The input end of the phase winding is connected to bridge arm L 3, C and the output end of the phase winding is connected to bridge arm L 4.

[0008] Another object of the present invention is to provide a modulation method for winding phase sequence switching of a series-wound motor winding phase sequence switching topology system. Under working conditions, by controlling the conduction or cut-off of four bipolar diodes, free switching between speed or torque modes can be achieved;

[0009] (1) When bipolar diode TR 1 and bipolar diode TR 4 are conducting, and bipolar diodes TR 2 and TR 3 are cut off, B the phase winding is connected in the positive direction, which can provide a high DC voltage utilization rate but cannot provide a large current, and is suitable for the motor to operate under high-speed and light-load conditions, which is the speed mode;

[0010] (2) When bipolar diodes TR 2 and TR 3 are conducting, TR 1 and TR 4 are cut off, B the phase winding is connected in the reverse direction, which can provide a large current but cannot provide a high DC voltage utilization rate, and is suitable for the motor to operate under low-speed and high-torque conditions, which is the torque mode.

[0011] Furthermore,TR 1 and TR 4 should have the same turn-on action; TR 2 and TR 3 have the same turn-on action to achieve smooth switching between the two topologies; TR 1 and TR 2 should have opposite turn-on actions to ensure that the motor windings are not short-circuited when the bipolar diode is turned on.

[0012] Furthermore, in the speed mode, the drive control is performed through the following steps:

[0013] In the speed mode, the control algorithm is adjusted to the speed drive mode;

[0014] Collect the current motor speed n , and set the reference motor speed n* ;

[0015] Perform speed deviation control calculation through the speed loop PI controller, and project the result onto d-q plane to obtain the reference current i q * ;

[0016] Set the reference current of the d-q axis to be zero; i d *、i 0 * ;

[0017] Collect the current phase currents i A , i B , i C , and after Clark transformation, project the result onto α-β-0 plane to obtain i α , i β and i 0 ;

[0018] Project i α , i β through Park transformation, and project the result onto d-q-0 plane to obtain the current d-q plane current i d , i q and i 0 ;

[0019] The reference current i q * 、 i d * and i 0 * as well as the current d-q-0 in the plane i d 、 i q 、i 0 The reference voltage is obtained through a PI controller u q * 、 u d *、u 0 * ;

[0020] The u q * 、 u d *、u 0 * is converted to the α-β-0 plane through Anti-Park ， to obtain the α-β-0 reference voltage in the plane u α * 、 u β *、u 0 * ;

[0021] The u α * 、 u β *、u 0 * is input into the inverter, and the u α * 、 u β *、u 0 * is converted to the abc coordinate system to obtain the abc reference voltage in the coordinate system u A * 、u B * 、 u C * 。

[0022] Let the duty cycle of leg L 1 be:

[0023] (1);

[0024] For leg L 2, the duty cycle is:

[0025] (2);

[0026] Wherein, V dc is the DC bus voltage.

[0027] For leg L 3, the duty cycle is:

[0028] (3);

[0029] For leg L 4, the duty cycle is:

[0030] (4);

[0031] Common-mode voltages are respectively injected into the duty cycles of the four legs:

[0032] (5);

[0033] The duty cycles of the four legs are obtained as follows:

[0034] (6);

[0035] The duty cycles of the four legs are respectively output to drive the three-phase series-wound motor to operate in the speed mode.

[0036] Furthermore, in the torque mode, adjustments are made through the following steps:

[0037] In the torque mode, the control algorithm is adjusted to the torque drive mode;

[0038] Collect the current motor speed n , and set the reference motor speed n* ;

[0039] Perform speed deviation control calculation through the speed-loop PI controller, and project the result onto the d-q plane to obtain the reference current i q* ;

[0040] Set the reference current i d *、i 0 * to zero;

[0041] Collect the current of each phase at present i A 、 i B 、 i C , and after Clark transformation, project the result onto the α-β-0 plane to obtain i α 、 i β and i 0 ;

[0042] Project i α 、 i β after Park transformation, and project the result onto the d-q-0 plane to obtain the current d-q plane current i d 、 i q and i 0 ;

[0043] Through the reference current i q * 、 i d * and i 0 * and the current d-q-0 plane of i d 、 i q 、i 0 Obtain the reference voltage through the PI controller u q * 、 u d *、u 0 * ;

[0044] Project u q * 、u d *、u 0 * Obtained through the Anti-Park transformation u α * 、 u β *、u 0 * ;

[0045] The u α * 、 u β *、u 0 * are input into the inverter, and the u α * 、 u β *、u 0 * are transformed into the abc coordinate system to obtain the u A * 、 u B * 、 u C * reference values;

[0046] Let the duty cycle of leg L 1 be:

[0047] (7);

[0048] The duty cycle of leg L 2 is:

[0049] (8);

[0050] Then the duty cycle of leg L 3 is:

[0051] (9);

[0052] Then the duty cycle of leg L 4 is:

[0053] (10);

[0054] Zero-sequence voltage is injected into the duty cycles of the four legs respectively:

[0055] (11);

[0056] The duty cycles of the four bridge arms are obtained as follows:

[0057] (12);

[0058] Output the duty cycles of the four bridge arms respectively to drive the three-phase series-wound motor to operate in torque mode.

[0059] Another object of the present invention is to provide an inverter, including the series-wound motor winding phase sequence switching topology system described above.

[0060] Combined with the above technical solutions and the solved technical problems, the advantages and positive effects of the technical solution to be protected by the present invention are as follows:

[0061] First, the present invention provides a modulation strategy for series-wound motor winding phase sequence switching. After online topology reconstruction of the series-wound motor, two online switching topologies of torque output mode and speed output mode are obtained. Then the present invention provides different modulation strategies suitable for these two topologies, so as to ensure that the motor operates stably in the torque output mode at low speed and heavy load, and the motor operates stably in the speed output mode at high speed and light load, effectively expanding the torque-speed operation range of the three-phase series-wound motor, enabling the motor to meet the performance requirements under different operating conditions; the proposed corresponding switching modulation algorithm is simple and easy to implement, and can achieve smooth control of different series-wound motor operation modes.

[0062] (1) The technical solution of the present invention fills the technical gap in the domestic and international industries:

[0063] Among many types of motor drive topologies, the series-wound motor topology shows unique advantages. Compared with the existing star-connected winding motors, the series-wound motor has significant advantages such as high DC bus voltage utilization rate and strong fault tolerance.

[0064] It should be noted that in application scenarios such as electric vehicles and ships, there are often certain restrictions on the DC bus voltage. For example, in electric vehicles, in order to expand the speed range of the vehicle, 800V silicon carbide platforms have been widely used. These methods improve the charging speed and expand the speed operation range by increasing the DC bus voltage level. However, these platforms are all based on star-connected winding motors, and this topology can only utilize 57.7% of the bus voltage utilization rate. The above advantages of the series-wound motor happen to highly match the requirements of these occasions, can better meet various requirements in practical applications, and have broad application prospects. However, when using this topology for driving, due to the middle bridge arm of the inverter L 2. L3 is subject to greater current stress, limiting the overall torque output capacity of the drive system. To reduce the arm stress and improve torque output, the B phase winding sequence can be changed. Connect the B input end of the phase winding to arm L 3, B and connect the output end of the phase winding to arm L 2. At this time, the current stress of the middle arms L 2 and L 3 will decrease and be equal to the current stress of the two side arms. Therefore, its torque output capacity can be improved. However, this topology reduces the utilization rate of the motor bus voltage and limits its application at high speeds.

[0065] Existing solutions do not propose a way to simultaneously meet the wide speed range and heavy load application modes. In addition, existing technologies do not provide a high-performance modulation switching algorithm for the two different drive modes. The present invention discloses a topology for switching the phase sequence of the windings of a three-phase series-wound motor, which divides the three-phase series-wound motor into two drive modes: speed mode and torque mode. In the speed mode, the series-wound motor can achieve 100% utilization rate of the bus voltage. In the torque mode, the wound-rotor can be applied to heavy load conditions. These two topologies can meet the industrial scenario requirements for wide speed and heavy load applications. By using four bipolar diodes, direct switching between these two drive modes can be achieved. However, considering that existing technologies do not provide a simple, intuitive, and effective drive algorithm for these two drive topologies, the present invention provides a modulation algorithm for the two drive topologies. This modulation algorithm is based on the carrier comparison method and has the advantages of being simple, intuitive, and easy to implement. The technical solution of the present invention can provide a feasible solution for the commercial application of the series-wound motor.

[0066] Second, the technical problems solved by the technical solution of the present invention in industrial applications.

[0067] 1) Limitations in switching between speed and torque modes in the prior art

[0068] In traditional three-phase motor control, the motor usually operates with a fixed winding configuration and cannot flexibly switch between speed mode and torque mode.

[0069] Conventional topologies cannot simultaneously take into account the two operating conditions of high-speed light load and low-speed high torque, resulting in the inability to fully optimize the system performance, especially in a variable load environment.

[0070] 2) Insufficient flexibility in winding configuration

[0071] The phase sequence of traditional motor windings is usually fixedly connected. Switching the operating mode requires relying on complex external hardware switching devices or multiple inverters, increasing the system complexity and cost.

[0072] The hardware switching of windings is prone to transient impacts during the switching process, which may damage the motor life and increase maintenance costs.

[0073] 3) It is difficult to balance current utilization rate and energy efficiency

[0074] During high-speed operation, the existing technology cannot fully utilize the DC bus voltage, resulting in energy waste.

[0075] During low-speed operation, the output current is insufficient to meet the high torque demand, restricting the applicability of the equipment under heavy-load conditions.

[0076] The remarkable technological progress of the present invention:

[0077] 1) An innovative topology for realizing dynamic switching of winding phase sequence

[0078] The present invention realizes the dynamic switching between the forward connection and reverse connection of the winding by designing a topology including four bridge arms and four bipolar diodes.

[0079] This topology can flexibly adjust the winding configuration of the motor without additional switching devices, thus realizing the free switching between the speed mode (high voltage utilization rate) and torque mode (large current output) in a single system.

[0080] The cooperative conduction and turn-off of the diodes ensure smooth switching, avoid winding short circuits and transient impacts, and improve the system reliability.

[0081] 2) Efficient utilization of DC bus voltage

[0082] In the speed mode, the utilization rate of the DC bus voltage is significantly improved by the forward connection of the winding, enhancing the energy efficiency of high-speed operation.

[0083] In the torque mode, a large current output is provided by the reverse connection of the winding to meet the requirements of low-speed heavy-load conditions, expanding the application scenarios of the motor.

[0084] 3) Flexibility of dual-mode operation

[0085] Combined with the control algorithm and topology, the system can dynamically adjust the working mode according to the load demand, realizing smooth switching between the speed and torque modes.

[0086] This flexibility is especially suitable for industrial equipment with variable working conditions, such as cranes, conveyor belts, and wind turbine generators, significantly improving the adaptability of the equipment.

[0087] 4) Optimization of motor performance and life

[0088] The present invention optimizes the modulation strategy to dynamically adjust the conduction time of the bipolar diodes and bridge arm switches, ensuring that the motor windings are not subject to voltage or current impacts during switching.

[0089] It can provide stable output characteristics in both modes, extending the service life of the motor and related electronic components.

[0090] 5) Reduce hardware costs and system complexity

[0091] This technical solution integrates multiple functions in a single topology, reducing the need for external switching devices and lowering hardware costs.

[0092] Using a single inverter can complete the winding phase sequence switching and control, simplifying the system design and reducing development and maintenance costs.

[0093] 6) Enhance industrial competitiveness

[0094] This invention significantly improves the operating efficiency and flexibility of the motor, solves the bottleneck problems of traditional technologies, and meets the requirements of modern industrial equipment for high performance, high efficiency, and multi-functionality.

[0095] The scalability of the technical solution makes it applicable to multiple fields such as industrial automation, transportation equipment, electric vehicles, and smart homes, providing strong technical support for industrial applications.

[0096] This invention solves problems such as low switching efficiency between speed and torque modes, insufficient winding flexibility, and motor performance limitations in traditional technologies through an innovative winding phase sequence switching topology and modulation strategy. Its significant technological progress is reflected in aspects such as topological flexibility, improved energy utilization efficiency, hardware simplification, and enhanced system reliability, providing an efficient and reliable solution for multi-scenario requirements in industrial applications. Brief Description of the Drawings

[0097] Figure 1 is the winding sequence switching topology structure diagram of the series-wound motor provided by the embodiment of the present invention;

[0098] Figure 2 is the topology diagram of the series-wound motor in the speed mode provided by the embodiment of the present invention;

[0099] Figure 3 is the topology diagram of the series-wound motor in the torque mode provided by the embodiment of the present invention;

[0100] Figure 4 is the winding sequence topology switching control block diagram of the series-wound motor provided by the embodiment of the present invention;

[0101] Figure 5 is the flowchart of the online control method for the topology switching of the series-wound motor provided by the embodiment of the present invention;

[0102] Figure 6It is the duty cycle simulation waveform diagram of the series-wound motor switching from torque mode to speed mode;

[0103] Figure 7 It is the simulation waveform diagram of the arm current stress of the series-wound motor switching from torque mode to speed mode;

[0104] Figure 8 It is the experimental waveform diagram of the torque mode of the series-wound motor;

[0105] Figure 9 It is the experimental waveform diagram of the speed mode of the series-wound motor. Specific implementation manners

[0106] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0107] The present invention constructs a series-wound motor winding phase sequence switching topology system through four bridge arms ( L 1, L 2, L 3, L 4) and four bipolar diodes ( TR 1, TR 2, TR 3, TR 4). Each bridge arm consists of two upper and lower power switches. The DC bus voltage source is connected to the upper node of the upper switch device of the bridge arm, and the power supply ground is connected to the lower node of the lower switch device of the bridge arm. The windings of the three-phase motor are connected in series through the bridge arms: A The phase winding is connected to bridge arms L 1 and L 2, B The phase winding is connected to bridge arms L 2 and L 3, C The phase winding is connected to bridge arms L 3 and L 4. The bipolar diodes (such as TR 1, TR 4) are used to control the winding phase sequence switching. Conducting or turning off the bipolar diodes can switch the positive or negative connection of the winding, realizing the dynamic adjustment of the speed mode and the torque mode.

[0108] In the speed mode, by conducting the bipolar diodes TR 1 and TR 4 (turning off TR 2 and TR 3), make BThe phase windings are connected in the positive direction. At this time, the motor can obtain a high utilization rate of DC voltage. However, due to the limited current, it is suitable for high-speed and light-load operating conditions. The control algorithm adjusts the motor operation to the speed drive mode, collects the current motor speed, compares it with the reference speed, calculates the speed deviation through the speed-loop PI controller, and generates d-q a planar reference current. Subsequently, the reference voltage is generated through the current-loop controller and transformed to the reference voltage in the abc coordinate system through the inverse Park transformation. These reference voltages are used to adjust the duty cycle of each bridge arm to drive the motor to operate in the speed mode.

[0109] In the torque mode, by turning on the bipolar diodes TR 2 and TR 3 (turning off TR 1 and TR 4), the B phase windings are connected in the reverse direction. At this time, the motor can output a large current, but the utilization rate of DC voltage is low, which is suitable for low-speed and high-torque operating conditions. The control algorithm is adjusted to the torque drive mode, the motor speed is collected, the speed deviation is calculated with the reference speed, and the reference current is generated. Similar to the speed mode, through the current control and voltage calculation in the d-q plane, three-phase reference voltages are generated to drive the motor. When a large current is output, the algorithm ensures a smooth switching process and avoids winding short circuits by dynamically adjusting the conduction time of the bipolar diodes.

[0110] The conduction and turn-off of the bipolar diodes need to cooperate with the actions of the bridge arm power switching devices. Specifically, TR 1 and TR 4 must be turned on or off simultaneously to achieve the speed mode; TR 2 and TR 3 must be turned on or off simultaneously to achieve the torque mode. At the same time, TR 1 and TR 2, TR 3 and TR 4 cannot be turned on simultaneously at any time to avoid motor winding short circuits. In addition, by dynamically adjusting the conduction state of the diodes, the system can achieve seamless switching between the two modes to ensure the stable operation of the motor in the speed and torque modes.

[0111] Whether in the speed mode or the torque mode, the system converts the three-phase current to the α-β-0 plane through the Clark transformation, and then obtains the current in the d-q-0 plane through the Park transformation. Combining with the reference current, the current-loop PI controller generates the corresponding reference voltage. The reference voltage adjusts the duty cycle of the bridge arm through the inverse Park transformation and the inverter to achieve precise control of the three-phase motor winding current and voltage.

[0112] When switching between the two modes, the controller dynamically adjusts the conduction state of the bipolar diodes and the duty cycle of the bridge arms by detecting the current rotational speed and load status, ensuring a smooth transition during the switching process. The common-mode voltage is introduced in the duty cycle adjustment to optimize the waveform quality and reduce high-frequency interference. At the same time, the switching frequency and conduction time of the bridge-arm power switches are precisely calculated to avoid sudden changes in the motor winding current and voltage, further improving the stability and efficiency of the system.

[0113] As Figure 1 shown, the present invention provides a series-wound motor speed-torque winding sequence switching topology system, including bridge arm L 1, bridge arm L 2, bridge arm L 3, bridge arm L 4 and bipolar diodes TR 1, TR 2, TR 3, TR 4.

[0114] A The input end of the phase winding is connected to bridge arm L 1, A and the output end of the phase winding is connected to bridge arm L 2; B The input end of the phase winding is connected to bridge arm L 2, TR 1 and TR 3, B and the output end of the phase winding is connected to bridge arm L 3, TR 2 and TR 4; C The input end of the phase winding is connected to bridge arm L 3, C and the output end of the phase winding is connected to bridge arm L 4;

[0115] As Figure 5 shown, the present invention provides a modulation method for series-wound motor topology switching, which realizes the free switching between the speed / torque modes by controlling the conduction / turn-off of four bipolar diodes.

[0116] To achieve a smooth switching between the two topologies, TR 1 and TR 4 should have the same conduction action; TR 2 and TR 3 have the same conduction action. In addition, to ensure that the motor winding is not short-circuited when the bipolar diode is conducting, TR 1 and TR 2 should have opposite conduction actions.

[0117] When the bipolar diodeTR 1 and bipolar diodes TR 4 conducts, bipolar diodes TR 2 and bipolar diodes TR When 3 is turned off B The phase windings are connected in the positive direction, which can provide a high utilization rate of DC voltage but cannot provide a large current. Therefore, it is suitable for the motor to operate under high-speed and light-load conditions, which is the speed mode. At this time, the connection method of the motor windings is as Figure 2 shown;

[0118] When the bipolar diodes TR 2 and bipolar diodes TR 3 conduct, and the bipolar diode TR 1 and bipolar diodes TR 4 is turned off B The phase windings are connected in the reverse direction, which can provide a large current but cannot provide a high utilization rate of DC voltage. Therefore, it is suitable for the motor to operate under low-speed and large-torque conditions, which is the torque mode. At this time, the connection sequence of the motor windings is as Figure 3 shown.

[0119] The present invention also proposes a CBPWM modulation strategy for the above-mentioned winding sequence switching. The purpose of this modulation strategy is to achieve a smooth output of the motor performance before and after the topology switching, and the output mode of the motor can be adjusted accordingly as expected after the switching ends. This modulation strategy includes:

[0120] When the operating condition is high-speed and light-load Figure 4 the modulation controller shown switches to the speed mode;

[0121] Collect the current motor speed n , and set the reference motor speed n* ;

[0122] Perform speed deviation control calculation through the speed loop PI controller, and project the result onto the d-q plane to obtain the reference current i q * ;

[0123] Set the reference current i d *、i 0 * to zero;

[0124] Collect the current phase currents i A , i B , i C , and after Clark transformation, project the result onto the α-β-0The plane, obtain i α 、 i β and i 0 ;

[0125] Apply i α 、 i β through Park transformation and project the result onto the d-q-0 plane to obtain the current d-q plane current i d 、 i q and i 0 ;

[0126] Through the reference current i q * 、 i d * and i 0 * and the current d-q-0 of the plane i d 、 i q 、i 0 Obtain the reference voltage u q * 、 u d *、u 0 * ;

[0127] Apply u q * 、 u d *、u 0 * through Anti - Park transformation to obtain u α * 、 u β *、u 0 * ;

[0128] Apply u α * 、 uβ *、u 0 * into the input inverter, and u α * , u β *、u 0 * transform it to abc the coordinate system to obtain u A * , u B * , u C * reference values.

[0129] Let the duty cycle of leg L 1 be:

[0130] (1);

[0131] Then the duty cycle of leg L 2 is:

[0132] (2);

[0133] The duty cycle of leg L 3 is:

[0134] (3);

[0135] The duty cycle of leg L 4 is:

[0136] (4);

[0137] Inject zero-sequence voltages into the duty cycles of the four legs respectively:

[0138] (5);

[0139] The obtained duty cycles of the four legs are respectively:

[0140] (6);

[0141] Output the duty cycles of the four legs respectively to drive the three-phase series-wound motor to operate in the speed mode.

[0142] When the operating condition is low speed and heavy load, Figure 4 the modulation controller shown switches to the torque mode;

[0143] Collect the current motor speed n and set the reference motor speed n* ;

[0144] Perform speed deviation control calculation through the speed loop PI controller and project the result onto d-q plane to obtain the reference current i q * ;

[0145] Set the reference current i d *、i 0 * to zero;

[0146] Collect the current phase currents i A 、 i B 、 i C , perform Clark transformation, project the result onto α-β-0 plane to obtain i α 、 i β and i 0 ;

[0147] Project i α 、 i β through Park transformation and project the result onto d-q-0 plane to obtain the current d-q plane current i d 、 i q and i 0 ;

[0148] Through the reference current i q * 、 i d * and i 0 * and the current d-q-0 plane's i d 、 i q 、i 0 Obtain the reference voltage u q* , u d *、u 0 * ;

[0149] Convert u q * , u d *、u 0 * to get u α * , u β *、u 0 * ;

[0150] Convert u α * , u β *、u 0 * input into the inverter, and convert u α * , u β *、u 0 * to abc coordinate system to get u A * , u B * , u C * reference values, and let the duty cycle of leg L 1 be:

[0151] (7);

[0152] Then the duty cycle of leg L 2 is:

[0153] (8);

[0154] The duty cycle of leg L 3 is:

[0155] (9);

[0156] LegL The duty ratio of 4 is:

[0157] (10);

[0158] Zero-sequence voltage is injected into the duty ratios of the four bridge arms respectively:

[0159] (11);

[0160] The obtained duty ratios of the four bridge arms are respectively:

[0161] (12);

[0162] The duty ratios of the four bridge arms are output respectively to drive the three-phase series-wound motor to operate in torque mode.

[0163] In the simulation environment, the obtained duty ratio waveform of the torque mode switching to the speed mode is as Figure 6 shown, and the bridge arm current waveform is as Figure 7 shown. It can be seen from the figure that when the series-wound motor operates in torque mode, the duty ratio amplitude is higher, indicating that its bus voltage utilization rate is lower; but the currents of each bridge arm are equal and the amplitude is smaller, indicating that its torque output ability is stronger. When the series-wound motor operates in speed mode, the duty ratio amplitude is lower, indicating that its bus voltage utilization rate is higher; but the current stress of the middle bridge arm is higher and the amplitude is larger, indicating that its torque output ability is weaker. The series-wound motor winding sequence switching topology and its modulation strategy disclosed in the present invention can effectively expand its speed-torque operation range, and the proposed modulation strategy can stably control the motor before and after the topology switching.

[0164] In order to verify the technical solution of the present invention, this solution has been verified in detail in the laboratory. A set of 1kW three-phase four-bridge-arm series-wound motor drive test bench is built in the laboratory. The parameters of the series-wound motor are as follows: the number of pole pairs is 4; the resistance is 1.52Ω; d the shaft inductance is 3.77mH; q the shaft inductance is 3.77mH; the zero-sequence inductance is 1.55mH; the rotor magnetic flux is 0.129Wb; the third harmonic of the rotor magnetic flux is 0.0059Wb; the rated speed is 2500rpm; the rated torque is 4N·m; the sampling frequency is 10kHz. The effectiveness of the modulation algorithm proposed in the present invention is verified through the motor drive experiment. The relevant experimental results are also reflected in the technical solution of the present invention.

[0165] The experimental platform tests the operation performance of the present invention under steady state and dynamic conditions. The speed is set to 200rpm and the load is 2N·m under steady state, and the obtained speed, i dq0 current, three-phase phase current, iαβThe experimental waveforms of current, duty cycle, and arm current are as follows Figure 8 and 9 shown

[0166] The experimental waveforms of the speed mode are as follows Figure 8 shown. It can be seen that the motor is operating at 200 rpm, 4 N·m, and the DC bus voltage is 50 V. It can be seen that in the torque mode, the four arm current values are close, and the peak-to-peak value is about 4.3 A. The duty cycle is about 0.9 p.u. The experimental waveform diagram of the speed mode is as follows Figure 9 shown. In the speed mode, the duty cycle is relatively small, about 0.6 p.u., and the peak-to-peak current flowing through the middle arm is about 7.8 A, which is greater than the current of the two side arms

[0167] As can be seen from the figure, under a 4 N·m load, in the speed mode, the current flowing through the middle two arms of the inverter is relatively large, and it cannot operate under heavy loads. However, its small duty cycle means that this mode can still operate at higher speeds. In the torque mode, the current flowing through the middle arm and the current of the two side arms are equal in magnitude and relatively small, which means that this mode can still drive a larger load. However, its large duty cycle means that this mode is difficult to operate at high speeds

[0168] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or a dedicated design software. Those of ordinary skill in the art can understand that the above devices and methods can be implemented using computer-executable instructions and / or included in the processor control code, for example, such code is provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and modules of the present invention can be implemented by hardware circuits of programmable hardware devices such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable logic devices such as field programmable gate arrays, or can be implemented by software executed by various types of processors, or can be implemented by a combination of the above hardware circuits and software, such as firmware

[0169] The above is only the specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention by those skilled in the art within the technical scope disclosed by the present invention shall be covered by the protection scope of the present invention

Claims

1. A modulation method for phase sequence switching of a series-wound motor winding, characterized in that, The phase sequence switching topology of the series-wound motor winding consists of four bridge arms, namely bridge arm L 1, L 2, L 3, L 4, and four bipolar diodes: TR 1, TR 2, TR 3, TR 4; each bridge arm consists of an upper and a lower power switching device; the DC bus voltage source is connected to the upper node of each upper power switching device, while the power ground is connected to the lower node of the lower power switching device; A The input terminal of the phase winding is connected to the bridge arm L 1, A The output terminal of the phase winding is connected to the bridge arm L 2; Bipolar diode TR The left end of 1 is connected to the bridge arm L 2 , and the right end is connected to B The input terminal of the phase winding; Bipolar diode TR The left end of 3 is connected to B The input terminal of the phase winding, and the right end is connected to the bridge arm L 3 ; Bipolar diode TR The left end of 2 is connected to the bridge arm L 2 , and the right end is connected to B The output terminal of the phase winding; Bipolar diode TR The left end of 4 is connected to B The output terminal of the phase winding, and the right end is connected to the bridge arm L 3; C The input terminal of the phase winding is connected to the bridge arm L 3, C The output terminal of the phase winding is connected to the bridge arm L 4; Under working conditions, by controlling the conduction or cutoff of four bipolar diodes, free switching between the speed or torque mode is achieved; (1) When bipolar diode TR 1 and bipolar diode TR 4 are conducting, and bipolar diode TR 2 and bipolar diode TR 3 are turned off, B The phase winding is connected in the positive direction, which can provide a high DC voltage utilization rate but cannot provide a large current. It is suitable for the motor to operate under high-speed and light-load conditions, and is the speed mode; (2)When the bipolar diodes TR 2 and TR 3 are conducting, TR 1 and TR 4 are turned off, B the phase windings are reversely connected, which can provide a large current but cannot provide a high DC voltage utilization rate. It is suitable for the motor to operate under the conditions of low speed and large torque, and is the torque mode; In the speed mode, drive control is carried out through the following steps: In the speed mode, the controller is adjusted to the speed drive mode; Collect the current motor speed n and set the reference motor speed n* ; The speed deviation control calculation is performed through the speed loop PI controller, and the result is projected onto d-q the plane to obtain the reference current i q * ; Set the reference current i d *、i 0 * to zero; Collect the current of each phase i A 、 i B 、 i C , after Clark transformation, project the result onto α-β-0 plane to obtain i α 、 i β and i 0 ; After i α , i β are subjected to Park transformation and the results are projected onto d-q-0 plane, the current d-q-0 plane current i d , i q and i 0 are obtained; Through the reference current i q * , i d * and i 0 * and current d-q-0 Flat i d , i q 、i 0 Get the reference voltage through the PI controller u q * , u d *、u 0 * ; will u q * , u d *、u 0 * obtain through the Anti-Park transformation u α * , u β *、u 0 * ; Put u α * and u β *、u 0 * into the input inverter, and convert u α * and u β *、u 0 * to abc the coordinate system to obtain u A * and u B * and u C * reference values, and let the duty cycle of leg L 1 be: , Then the bridge arm L The duty cycle of 2 is: , Bridge arm L The duty cycle of 3 is as follows: , Bridge arm L The duty cycle of 4 is as follows: , Zero-sequence voltages are respectively injected into the duty ratios of the four bridge arms: , The obtained duty ratios of the four bridge arms are respectively: , The duty ratios of the four bridge arms are respectively output to drive the three-phase series-wound motor to operate in the speed mode; In the torque mode, adjustment is carried out through the following steps: In the torque mode, the controller is adjusted to the torque drive mode; Collect the current motor speed n and set the reference motor speed n* ; The rotational speed deviation control calculation is performed through a rotational speed loop PI controller, and the result is projected onto d-q a plane to obtain a reference current i q * ; Set the reference current i d *、i 0 * to zero; Collect the current of each phase i A 、 i B 、 i C , after Clark transformation, project the result onto the α-β-0 plane to obtain i α 、 i β and i 0 ; The i α , i β are subjected to Park transformation, and the result is projected onto the d-q-0 plane to obtain the current d-q-0 plane current i d , i q and i 0 ; Through a reference current i q * 、 i d * and i 0 * as well as the current d-q-0 plane's i d 、 i q 、i 0 A reference voltage is obtained through a PI controller u q * 、 u d *、u 0 * ; will u q * , u d *、u 0 * obtained through the Anti-Park transformation u α * , u β *、u 0 * ; Put u α * , u β *、u 0 * into the input inverter, and transform u α * , u β *、u 0 * to abc the coordinate system to obtain u A * , u B * , u C * reference values, and let the duty cycle of leg L 1 be: , Then the bridge arm L The duty cycle of 2 is as follows: , Bridge arm L The duty cycle of 3 is as follows: , Bridge arm L The duty cycle of 4 is: , Zero-sequence voltages are respectively injected into the duty ratios of the four bridge arms: , The obtained duty ratios of the four bridge arms are respectively: , The duty ratios of the four bridge arms are respectively output to drive the three-phase series-wound motor to operate in the torque mode.

2. The modulation method for phase sequence switching of the series-wound motor winding according to claim 1, wherein, TR 1 and TR 4 should have the same turn-on action; TR 2 and TR 3 have the same turn-on action to achieve smooth switching between the two topologies; TR 1 and TR 2 should have opposite turn-on actions to ensure that the motor winding is not short-circuited when the bipolar diode is turned on.

3. An inverter, characterized in that, The inverter adopts the modulation method for switching the phase sequence of the windings of the series-wound motor as described in any one of claims 1-2.

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