Four-leg voltage-fed flying capacitor switched reluctance motor converter and control method thereof
By designing a four-branch variable-voltage freewheeling DC-DC switched reluctance motor converter, independent connection and selectable freewheeling for each phase winding are achieved, solving the problem that converters in the existing technology cannot be controlled by voltage transformation, and improving the application performance of the motor in DC grids and high-voltage loads.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA JILIANG UNIV
- Filing Date
- 2024-12-03
- Publication Date
- 2026-06-05
AI Technical Summary
Existing switched reluctance motor converters cannot achieve voltage transformation control during excitation and power generation, which requires external transformer equipment, increases costs and losses, and cannot flexibly adjust the output voltage, limiting their application in DC grids and high-voltage loads.
The converter adopts a four-branch transformer freewheeling direct-lift switched reluctance motor converter. Through the design of the main circuit and power supply circuit, the four branch windings of each phase winding are independently connected, either in parallel or in series to achieve enhanced excitation and high-voltage power supply. It also adds an optional freewheeling stage. The power supply circuit uses only one switching transistor to reduce switching losses and regulates the voltage through PWM.
It enables flexible voltage regulation of switched reluctance motors during excitation and power generation, reduces the need for external voltage boosting devices, lowers switching losses, improves system flexibility and efficiency, and adapts to high-voltage loads and grid demands.
Smart Images
Figure CN122159684A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of motor systems, and specifically to a switched reluctance motor converter with individually connected branch windings, fully variable voltage and direct boost output, and continuous current capability, as well as its control method. Background Technology
[0002] In the motor industry, ordinary DC motors, ordinary AC asynchronous and synchronous motors, as well as special stepper motors and brushless DC motors are the mainstream products in their respective fields. In the history of motor development, whether it is electrical drive, industrial control, or electric vehicle drive, most fields have followed the trajectory of switching from DC motor applications to AC motor applications. At present, the application of ordinary DC motors is very rare. In small and medium power applications, brushless DC motors have a certain market share, but these motors are basically permanent magnet type, which has a high cost and limits their use to small and medium power ranges.
[0003] With the development of new energy power, represented by photovoltaic power generation which directly outputs direct current (DC), the generation and transmission of DC power has become a research, experimentation and development direction. From ultra-high voltage long-distance DC transmission to small-scale distributed DC grids, rapid development has been achieved in recent years. However, most power generation systems other than photovoltaic power generation are AC generators. From thermal power, hydropower, nuclear power, wind power and other generator sets, almost all are AC generators that directly generate AC power. If they encounter a DC grid, rectifier devices must be added, which inevitably increases costs and losses and reduces power efficiency.
[0004] In addition, the emerging industries represented by electric vehicles are developing rapidly. Almost all energy storage devices, such as batteries, need to be charged with DC power, and their direct output is also DC power. Therefore, the surrounding AC systems connected to them must add rectifier or inverter devices.
[0005] In short, direct current is increasingly becoming the new favorite for the generation, transmission, distribution, and use of electricity.
[0006] Switched reluctance motors are special motors that can easily achieve four-quadrant operation even under unidirectional current. As a generator, they can directly generate DC power, while as a motor, they consume DC power. Furthermore, they have a simple and robust structure, do not require permanent magnet materials, have low cost, and the rotor has no windings, making heat dissipation convenient. They have high torque, low current, and short start-up time, making them particularly suitable for high-speed and harsh environments.
[0007] The converter (also known as a power converter) of a switched reluctance motor is the heart of its operation. Because of the principle of the switched reluctance motor, its different phase windings are energized in a time-sharing manner according to the relative position relationship between the stator and rotor. Therefore, the operation and performance of the switched reluctance motor can be controlled by controlling the turn-on and turn-off angles of each phase winding. At low speeds, current chopping mode can also be used to prevent excessive phase winding current. In recent years, the emergence of new types of converters, some of which change their power supply or excitation voltage, i.e., transformer control, has provided a new variable for the development of switched reluctance motor systems.
[0008] The traditional converter structure of switched reluctance motors is an asymmetrical half-bridge type. When operating as a generator, it can realize the three stages of excitation, freewheeling and power generation. When operating as a motor, it has energy regeneration and is widely used. However, if voltage transformation control is required, it cannot be achieved by itself and can only rely on external voltage transformation equipment.
[0009] How to quickly establish phase winding current within a safe range for each phase of a switched reluctance motor has always been one of the research directions that the industry has been striving to explore. Especially when running at high speed, that is, when running as a generator, how to strengthen excitation and improve power generation efficiency, and when running as a motor, how to improve power density and fast start-up, etc. Increasing the supply voltage is undoubtedly one of the solutions, but the actual range of increase is limited.
[0010] Some new converter structures that have emerged recently, when the switched reluctance motor is used as a generator, mostly cannot have a selectable freewheeling link like the asymmetric half-bridge converter. Adding an optional freewheeling link between the excitation stage and the power generation stage is still very meaningful for enhancing the controllability and flexibility of the system.
[0011] When a switched reluctance motor is used as a generator, its direct DC output power is either supplied to a DC load or connected to the DC grid for larger-scale power consumption. The grid voltage is often much higher than the voltage directly generated by a traditional generator. Although there is no inverter or rectifier stage, a dedicated booster device is required, which increases cost and losses and reduces efficiency. Therefore, if the switched reluctance generator converter itself can directly boost the output voltage, it will be of great significance. In addition, the adjustability of the output voltage to adapt to the needs of the load or the grid is also an important indicator for evaluating system performance.
[0012] With the development of power electronic systems, the switching losses of switching transistors have gradually become one of the main culprits for reducing system efficiency. Therefore, the design of new converters for switched reluctance motors should also focus on minimizing the number of switching transistors used and minimizing the workload of switching transistors during operation. Summary of the Invention
[0013] Purpose of the invention: The purpose of this invention is to provide a switched reluctance motor converter and its control method, which features four branch windings of each phase independently connected to the main circuit for parallel excitation or high-voltage power supply and series direct voltage increase output, selectable half-voltage freewheeling link, fully intermodulated power supply circuit voltage and main circuit output voltage, low switching loss and high conversion efficiency.
[0014] Technical solution: A four-branch transformer freewheeling direct-drive switched reluctance motor converter, consisting of a main circuit and a power supply circuit. The output terminals of the main circuit are connected to the input terminals of the power supply circuit, and the output terminals of the power supply circuit are connected to the input terminals of the main circuit.
[0015] The main circuit includes: a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a fifth switching transistor, a sixth switching transistor, a seventh switching transistor, an eighth switching transistor, a ninth switching transistor, a tenth switching transistor, an eleventh switching transistor, a twelfth switching transistor, a thirteenth switching transistor, a fourteenth switching transistor, a fifteenth switching transistor, a first diode, a second diode, a third diode, a fourth diode, a fifth diode, a sixth diode, a seventh diode, an eighth diode, a ninth diode, a first capacitor, a second capacitor, the first branch winding of the first phase winding, the second branch winding of the first phase winding, the third branch winding of the first phase winding, the fourth branch winding of the first phase winding, the first branch winding of the second phase winding, the second branch winding of the second phase winding, the third branch winding of the second phase winding, and the second phase... The third phase winding consists of four windings: the fourth branch, the first branch, the second branch, the third branch, and the fourth branch. The anode of the first switch is connected to the anodes of the second and third switches, the anode of the first diode, and the anode of the fourth diode, serving as the positive input terminal of the main circuit. The cathode of the first switch is connected to one end of the first branch of the first phase winding. The cathode of the second switch is connected to one end of the first branch of the second phase winding. The cathode of the third switch is connected to one end of the first branch of the third phase winding. The other end of the first branch of the first phase winding is connected to the other end of the first branch of the second phase winding, the other end of the first branch of the third phase winding, the anode of the second diode, and the anode of the third diode. The cathode of the second diode is connected to the first... The circuit consists of a diode cathode, a fourth switch anode, a fifth switch anode, and a sixth switch anode. The fourth switch cathode is connected to one end of the second branch winding of the first phase winding. The fifth switch cathode is connected to one end of the second branch winding of the second phase winding. The sixth switch cathode is connected to one end of the second branch winding of the third phase winding. The other end of the second branch winding of the first phase winding is connected to the other end of the second branch winding of the second phase winding, the other end of the second branch winding of the third phase winding, the third diode cathode, the seventh switch anode, the fifth diode anode, and one end of the first capacitor. The other end of the first capacitor is connected to the fourth diode cathode, the eighth switch anode, and the ninth diode anode. The eighth switch cathode is connected to the ninth switch cathode, the eighth diode anode, one end of the second capacitor, and the first phase winding. One end of the third branch of the first phase winding, one end of the third branch of the second phase winding, and one end of the third branch of the third phase winding serve as the negative terminal of the main circuit output. The other end of the third branch of the first phase winding is connected to the anode of the tenth switch transistor. The other end of the third branch of the second phase winding is connected to the anode of the eleventh switch transistor. The other end of the third branch of the third phase winding is connected to the anode of the twelfth switch transistor. The cathode of the tenth switch transistor is connected to the cathodes of the eleventh and twelfth switch transistors, the anode of the sixth diode, and the anode of the seventh diode. The cathode of the seventh diode is connected to the cathode of the eighth diode. One end of the fourth branch of the first phase winding, one end of the fourth branch of the second phase winding, and one end of the fourth branch of the third phase winding are also connected. The other end of the fourth branch of the first phase winding is connected to the anode of the thirteenth switch transistor.The other end of the fourth branch of the second phase winding is connected to the anode of the fourteenth switch transistor. The other end of the fourth branch of the third phase winding is connected to the anode of the fifteenth switch transistor. The cathode of the thirteenth switch transistor is connected to the cathodes of the fourteenth, fifteenth, sixth, and seventh switches, serving as the negative input terminal of the main circuit. The anode of the ninth switch transistor is connected to the cathode of the fifth diode, and the cathode of the ninth diode is connected to the other end of the second capacitor, serving as the positive output terminal of the main circuit. The first, second, third, and fourth branch windings of the first phase winding constitute the first phase winding. The first, second, third, and fourth branch windings of the second phase winding constitute the second phase winding. The first, second, third, and fourth branch windings of the third phase winding constitute the third phase winding.
[0016] The power supply circuit includes: a sixteenth switching transistor, a tenth diode, an eleventh diode, a twelfth diode, a thirteenth diode, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a first inductor, a second inductor, a third inductor, and an isolation converter. The positive input terminal of the isolation converter serves as the positive input terminal of the power supply circuit and is connected to the positive output terminal of the main circuit. The negative input terminal of the isolation converter serves as the negative input terminal of the power supply circuit and is connected to the negative output terminal of the main circuit. The positive output terminal of the isolation converter is connected to one end of the first inductor. The other end of the first inductor is connected to the anode of the tenth diode and one end of the third capacitor. The cathode of the tenth diode is connected to the anode of the eleventh diode, one end of the fourth capacitor, and one end of the second inductor. The cathode of the diode is connected to the anode of the thirteenth diode and one end of the sixth capacitor. The other end of the sixth capacitor is connected to the anode of the sixteenth switch, one end of the fifth capacitor, and the other end of the second inductor. The cathode of the thirteenth diode is connected to one end of the eighth capacitor and serves as the positive output terminal of the power supply circuit, connected to the positive input terminal of the main circuit. The cathode of the sixteenth switch is connected to the other end of the fourth capacitor, one end of the seventh capacitor, and one end of the third inductor. The other end of the seventh capacitor is connected to the anode of the twelfth diode and serves as the negative output terminal of the power supply circuit, connected to the negative input terminal of the main circuit. The cathode of the twelfth diode is connected to the other end of the third capacitor, the other end of the fifth capacitor, the other end of the third inductor, and the negative output terminal of the isolation converter. The isolation converter is a magnetically isolated DC / DC converter.
[0017] The control method for a four-branch transformer-assisted direct-drive switched reluctance motor converter, specifically the main circuit control method, involves the switched reluctance motor operating as a generator. The power supply circuit outputs electrical energy as the excitation power for each phase winding of the main circuit. Based on rotor position information, when the first phase winding needs to be engaged, the first, fourth, seventh, eighth, tenth, and thirteenth switches are closed, entering the first operating stage of the first phase winding, i.e., the excitation stage. The excitation power supply provides excitation power to each branch winding of the first phase winding, while the first capacitor is charged. The main circuit output is maintained by the second capacitor. Based on rotor position information, when the excitation stage needs to end, the seventh and eighth switches are turned off. If the ninth switch is closed at this time, the second operating stage of the first phase winding begins. During the half-voltage freewheeling stage of the first phase winding releasing stored energy, each branch winding of the first phase winding forms a closed loop with the input excitation power supply, and the voltage of each branch winding is half of the excitation power supply voltage. When the second working stage, i.e. the half-voltage freewheeling stage, needs to end, the ninth switch is disconnected, and the first phase winding enters the third working stage, i.e. the power generation stage. If the second working stage is not needed, the ninth switch does not need to be closed at the end of the excitation stage, and the first phase winding directly enters the power generation stage. After the four branch windings of the first phase winding are connected in series, their stored energy, together with the excitation power supply, is output to the main circuit output terminal through the ninth diode and charges the second capacitor. According to the rotor position information, when the first phase winding needs to end its work, the first, fourth, tenth, and thirteenth switches are disconnected, and the first phase winding ends its work.
[0018] Based on the rotor position information, when the second phase winding needs to be put into operation, compared to the operation process of the first phase winding, only the second switch transistor needs to replace the first switch transistor, the fifth switch transistor needs to replace the fourth switch transistor, the eleventh switch transistor needs to replace the tenth switch transistor, and the fourteenth switch transistor needs to replace the thirteenth switch transistor, with the rest being the same; based on the rotor position information, when the third phase winding needs to be put into operation, compared to the operation process of the first phase winding, only the third switch transistor needs to replace the first switch transistor, the sixth switch transistor needs to replace the fourth switch transistor, the twelfth switch transistor needs to replace the tenth switch transistor, and the fifteenth switch transistor needs to replace the thirteenth switch transistor, with the rest being the same.
[0019] The control method of a four-branch transformer freewheeling direct-drive switched reluctance motor converter, specifically the main circuit control method, involves the following steps: When the switched reluctance motor operates as a motor, the power supply circuit outputs electrical energy as the power supply for each phase winding of the main circuit. Based on the rotor position information, when the first phase winding needs to be put into operation, the first, fourth, seventh, eighth, tenth, and thirteenth switches are closed and turned on, entering the first working stage of the first phase winding, i.e., the main motor operation stage. The power supply circuit supplies power to each branch winding of the first phase winding, and the first capacitor is charged. The output of the main circuit is maintained by the second capacitor. Based on the rotor position information, when the first phase winding needs to be put into operation, the seventh and eighth switches are turned off, and the energy stored in each branch winding of the first phase winding is released to the output of the main circuit. When the next phase winding is about to be put into operation according to the rotor position information, the first, fourth, tenth, and thirteenth switches are turned off, and the operation of the first phase winding ends.
[0020] Based on the rotor position information, when the second phase winding needs to be put into operation, compared to the operation process of the first phase winding, only the second switch transistor needs to replace the first switch transistor, the fifth switch transistor needs to replace the fourth switch transistor, the eleventh switch transistor needs to replace the tenth switch transistor, and the fourteenth switch transistor needs to replace the thirteenth switch transistor, with the rest being the same; based on the rotor position information, when the third phase winding needs to be put into operation, compared to the operation process of the first phase winding, only the third switch transistor needs to replace the first switch transistor, the sixth switch transistor needs to replace the fourth switch transistor, the twelfth switch transistor needs to replace the tenth switch transistor, and the fifteenth switch transistor needs to replace the thirteenth switch transistor, with the rest being the same.
[0021] The control method of a four-branch transformer freewheeling direct-drive switched reluctance motor converter, and the control method of the power supply circuit, wherein the sixteenth switch operates in PWM mode. The power supply circuit has two operating stages. In the first operating stage, when the sixteenth switch is closed and conducting, the tenth and thirteenth diodes are reverse-biased and cut off. The input energy through the isolation converter charges the first inductor and the third capacitor, while the fourth and fifth capacitors discharge. The sixth, seventh, second, and third inductors are charged, and the output side of the power supply circuit is maintained by the eighth capacitor. When the sixteenth switch is turned off, the second operating stage begins, and the tenth and thirteenth diodes conduct, receiving and outputting input energy. All the components charged in the first operating stage discharge, and the discharged components are charged. When the PWM duty cycle of the sixteenth switch K16 is adjusted, the output voltage of the power supply circuit will change.
[0022] The beneficial effects of this invention are:
[0023] 1. In the switched reluctance motor of the present invention, the four branch windings of each phase winding are independently connected in the main circuit. In the operation of excitation power generation or power output, the branch windings are connected in parallel. The voltage of the four branch windings of each phase is significantly greater than one-quarter of the output voltage of the power supply circuit, thereby realizing enhanced excitation or high-voltage power supply. This is of great significance for quickly establishing the winding current, thereby reducing the pressure of subsequent regulation and providing a basic guarantee for enhancing system performance.
[0024] 2. When the switched reluctance motor is used as a generator, an optional freewheeling stage is added. Unlike the traditional voltageless freewheeling, this invention achieves a relative half-voltage freewheeling, providing an opportunity for mid-operation adjustment and enabling more flexible control and operation of the converter.
[0025] 3. When the switched reluctance motor is used as a generator, its operation process can be seen, especially in the generation stage, the excitation power supply, the first capacitor, and the four branch windings are all connected in series to generate output, which greatly improves the output voltage value, adapting to the high voltage requirements of grid connection or high voltage load, and reducing the need for a dedicated voltage boosting device; and when the output voltage of the power supply circuit is adjustable, the output voltage value of the main circuit can be indirectly adjusted, thus providing an adjustable variable directly for grid connection or load operation on the output side.
[0026] 4. The power supply circuit has only one switching transistor, which minimizes the switching losses of the power supply circuit; although the main circuit has as many as 15 switching transistors, at any given moment at least eight switching transistors are not working; thus, the overall switching losses of the converter are kept low.
[0027] 5. By adjusting the PWM duty cycle of its single switching transistor, the power supply circuit can adjust its output voltage value, thereby achieving variable excitation voltage control for the switched reluctance generator or variable speed control for the switched reluctance motor; thus, the entire converter can achieve fully variable port voltage. Attached Figure Description
[0028] Figure 1 The diagram shown is the main circuit structure of the four-branch transformer freewheeling direct-lift switched reluctance motor converter of the present invention.
[0029] Figure 2 The diagram shown is a power circuit structure diagram of the four-branch transformer freewheeling direct-lift switched reluctance motor converter of the present invention.
[0030] Figure 3 The diagram shows the first operating stage of the first phase winding of the main circuit of this invention.
[0031] Figure 4 The diagram shows the second operating stage of the first phase winding of the main circuit of this invention.
[0032] Figure 5The diagram shows the third operating stage of the first phase winding of the main circuit of this invention.
[0033] Figure 6 The diagram shows the first operating stage of the power supply circuit of the present invention.
[0034] Figure 7 The diagram shows the second operating stage of the power supply circuit of this invention. Detailed Implementation
[0035] A four-branch transformer-driven freewheeling switched reluctance motor converter and its control method are described. The converter consists of a main circuit and a power supply circuit, as shown in the attached diagram. Figure 1 As shown in the attached diagram, the power supply circuit is... Figure 2 As shown, the two ends of the main circuit output are connected to the two ends of the power supply circuit input, and the two ends of the power supply circuit output are connected to the two ends of the main circuit input. The two ends of the main circuit output can also be connected to an external load or a power supply network, including a DC power grid.
[0036] Each phase winding of the switched reluctance motor is connected to the main circuit. In this embodiment, the switched reluctance motor is a three-phase winding with a stator of 12 poles and a rotor of 8 poles. The phase windings are wound on the stator salient poles. Each phase winding has four branch windings, and each of the four branch windings of each phase winding is independently led out to its two ends and connected to the main circuit.
[0037] The main circuit includes: first switch K1, second switch K2, third switch K3, fourth switch K4, fifth switch K5, sixth switch K6, seventh switch K7, eighth switch K8, ninth switch K9, tenth switch K10, eleventh switch K11, twelfth switch K12, thirteenth switch K13, fourteenth switch K14, fifteenth switch K15; first diode D1, second diode D2, third diode D3, fourth diode D4, fifth diode D5, sixth diode D6, and seventh diode D7. The components are: 8th diode D8, 9th diode D9, 1st capacitor C1, 2nd capacitor C2, 1st phase winding M1, 1st phase winding M2, 1st phase winding M3, 1st phase winding M4, 2nd phase winding N1, 2nd phase winding N2, 2nd phase winding N3, 2nd phase winding N4, 3rd phase winding P1, 3rd phase winding P2, 3rd phase winding P3, and 3rd phase winding P4, as shown in the appendix. Figure 1As shown, the anode of the first switch K1 is connected to the anodes of the second switch K2, the third switch K3, the first diode D1, and the fourth diode D4, serving as the positive input terminal of the main circuit. The cathode of the first switch K1 is connected to one end of the first branch winding M1 of the first phase winding. The cathode of the second switch K2 is connected to one end of the first branch winding N1 of the second phase winding. The cathode of the third switch K3 is connected to one end of the first branch winding P1 of the third phase winding. The other end of the first branch winding M1 of the first phase winding is connected to the other end of the first branch winding N1 of the second phase winding, the other end of the first branch winding P1 of the third phase winding, the anode of the second diode D2, and the anode of the third diode D3. The cathode of the second diode D2 is connected to the cathode of the first diode D1, the anode of the fourth switch K4, and the anode of the third diode D4. The anodes of the fifth switch transistor K5 and the sixth switch transistor K6 are connected to the cathode of the fourth switch transistor K4, which is connected to one end of the second branch winding M2 of the first phase winding. The cathode of the fifth switch transistor K5 is connected to one end of the second branch winding N2 of the second phase winding. The cathode of the sixth switch transistor K6 is connected to one end of the second branch winding P2 of the third phase winding. The other end of the second branch winding M2 of the first phase winding is connected to the other end of the second branch winding N2 of the second phase winding, the other end of the second branch winding P2 of the third phase winding, the cathode of the third diode D3, the anode of the seventh switch transistor K7, the anode of the fifth diode D5, and one end of the first capacitor C1. The other end of the first capacitor C1 is connected to the cathode of the fourth diode D4, the anode of the eighth switch transistor K8, and the anode of the ninth diode D9. The cathode of the eighth switch transistor K8 is connected to the ninth switch transistor. The cathode of transistor K9, the anode of the eighth diode D8, one end of the second capacitor C2, one end of the third branch winding M3 of the first phase winding, one end of the third branch winding N3 of the second phase winding, and one end of the third branch winding P3 of the third phase winding serve as the negative terminal of the main circuit output. The other end of the third branch winding M3 of the first phase winding is connected to the anode of the tenth switch transistor K10. The other end of the third branch winding N3 of the second phase winding is connected to the anode of the eleventh switch transistor K11. The other end of the third branch winding P3 of the third phase winding is connected to the anode of the twelfth switch transistor K12. The cathode of the tenth switch transistor K10 is connected to the cathodes of the eleventh switch transistor K11 and the twelfth switch transistor K12, the anode of the sixth diode D6, and the anode of the seventh diode D7. The cathode of the seventh diode D7 is connected to the cathode of the eighth diode D8. One end of the fourth winding M4 of the first phase winding, one end of the fourth winding N4 of the second phase winding, and one end of the fourth winding P4 of the third phase winding are connected. The other end of the fourth winding M4 of the first phase winding is connected to the anode of the thirteenth switch transistor K13. The other end of the fourth winding N4 of the second phase winding is connected to the anode of the fourteenth switch transistor K14. The other end of the fourth winding P4 of the third phase winding is connected to the anode of the fifteenth switch transistor K15. The cathode of the thirteenth switch transistor K13 is connected to the cathodes of the fourteenth switch transistor K14, the fifteenth switch transistor K15, the sixth diode D6, and the seventh switch transistor K7, and serves as the negative input terminal of the main circuit. The anode of the ninth switch transistor K9 is connected to the cathode of the fifth diode D5, and the cathode of the ninth diode D9 is connected to the other end of the second capacitor C2.And serve as the positive terminal of the main circuit output; the first phase winding M consists of the first branch winding M1, the second branch winding M2, the third branch winding M3, and the fourth branch winding M4; the second phase winding N consists of the first branch winding N1, the second branch winding N2, the third branch winding N3, and the fourth branch winding N4; the third phase winding P consists of the first branch winding P1, the second branch winding P2, the third branch winding P3, and the fourth branch winding P4.
[0038] The power supply circuit includes: the sixteenth switching transistor K16, the tenth diode D10, the eleventh diode D11, the twelfth diode D12, the thirteenth diode D13, the third capacitor C3, the fourth capacitor C4, the fifth capacitor C5, the sixth capacitor C6, the seventh capacitor C7, the eighth capacitor C8, the first inductor L1, the second inductor L2, the third inductor L3, and an isolation converter, as shown in the attached diagram. Figure 2 As shown, the positive input terminal of the isolation converter is connected to the positive output terminal of the main circuit as the positive input terminal of the power supply circuit. The negative input terminal of the isolation converter is connected to the negative output terminal of the main circuit as the negative input terminal of the power supply circuit. The positive output terminal of the isolation converter is connected to one end of the first inductor L1. The other end of the first inductor L1 is connected to the anode of the tenth diode D10 and one end of the third capacitor C3. The cathode of the tenth diode D10 is connected to the anode of the eleventh diode D11, one end of the fourth capacitor C4, and one end of the second inductor L2. The cathode of the eleventh diode D11 is connected to the anode of the thirteenth diode D13 and one end of the sixth capacitor C6. The other end of the sixth capacitor C6 is connected to the anode of the sixteenth switch K16 and the fifth capacitor C5. One end of the first diode, and the other end of the second inductor L2, are connected to one end of the eighth capacitor C8, and serve as the positive output terminal of the power supply circuit connected to the positive input terminal of the main circuit. The cathode of the sixteenth switching transistor K16 is connected to the other end of the fourth capacitor C4, one end of the seventh capacitor C7, and one end of the third inductor L3. The other end of the seventh capacitor C7 is connected to the anode of the twelfth diode D12, and serves as the negative output terminal of the power supply circuit connected to the negative input terminal of the main circuit. The cathode of the twelfth diode D12 is connected to the other end of the third capacitor C3, the other end of the fifth capacitor C5, the other end of the third inductor L3, and the negative output terminal of the isolation converter. The isolation converter is a magnetically isolated DC / DC converter.
[0039] All switching transistors in the main circuit and power supply circuit are three-terminal fully controlled power electronic switching devices.
[0040] Example 1 of the main circuit control method: When the switched reluctance motor operates as a generator, the power supply circuit outputs electrical energy as the excitation power for each phase winding of the main circuit. According to the rotor position information, when the first phase winding M needs to be put into operation, the first switch K1, the fourth switch K4, the seventh switch K7, the eighth switch K8, the tenth switch K10, and the thirteenth switch K13 are closed and turned on, entering the first working stage of the first phase winding M, namely the excitation stage, as shown in the attached diagram. Figure 3 As shown, the excitation power supply provides excitation to each branch of the first phase winding M, while the first capacitor C1 is charged. The output of the main circuit is maintained by the second capacitor C2. The first switch K1, the first branch of the first phase winding M1, and the branch of the third diode D3 are connected in parallel with the branch of the first diode D1, the fourth switch K4, and the second branch of the first phase winding M2. The voltage of each branch is equal to the excitation power supply voltage, i.e., the excitation voltage. The third branch of the first phase winding M3, the tenth switch K10, the sixth diode D6, and the eighth diode D8 are also connected in parallel. The fourth branch of the first phase winding M4 and the branch of the thirteenth switch K13 are connected in parallel. The voltage of each branch is also equal to the excitation voltage. That is, all four branches of the first phase winding M are connected in parallel. If the voltage drop of the tubes is ignored, the terminal voltage of each branch of the first phase winding M is equal to the excitation power supply voltage. According to the rotor position information, when the excitation stage needs to end, the seventh switch K7 and the eighth switch K8 are turned off. According to the current of the first phase winding M, if the ninth switch K9 is turned on at the same time, the second working stage of the first phase winding M is entered, as shown in the appendix. Figure 4 As shown, although the branches of the first winding M1 and the second winding M2 of the first phase are still in parallel, and the branches of the third winding M3 and the fourth winding M4 of the first phase are also in parallel, they are connected in series via the fifth diode D5 and the ninth switch K9. Therefore, the terminal voltage of each branch of the first phase winding M is half the excitation voltage and in reverse. According to the mathematical model of the switched reluctance motor:
[0041]
[0042] In equation (1), U is the excitation voltage; i is the phase winding current; L is the phase winding inductance; Ω is the angular velocity of the switched reluctance motor; and θ is the switching angle. The electromotive force of the transformer is the electromotive force induced by the change in phase current. It represents the difference between the phase winding and a simple inductance. It is the electromotive force induced when the motor rotates due to the change of phase inductance with the rotor position, and is called the kinetic electromotive force.
[0043] As can be seen from equation (1), when the stored energy of each branch winding is released, the terminal voltage reverses and the external voltage, i.e., the excitation voltage, is applied to the branch winding and drops to half of its original value. This stage is similar to the optional freewheeling stage in the middle of the excitation and generation stages of a traditional asymmetrical half-bridge converter of a switched reluctance motor. However, this embodiment is not a voltage-free freewheeling stage, but a half-voltage freewheeling stage. Compared with the full-voltage excitation, the current of each branch winding will change, thereby meeting the system's demand for the phase winding current. When the second working stage, i.e. the half-voltage freewheeling stage, ends, the ninth switch K9 needs to be disconnected to enter the third working stage of the first phase winding M, i.e., the generation stage. If the second working stage is not needed, the ninth switch does not need to be closed at the end of the excitation stage, and the generation stage can be directly entered. The third working stage of the first phase winding M, i.e., the generation stage, is shown in the attached figure. Figure 5 As shown, after the four branch windings of the first phase winding M are connected in series, their stored energy, together with the excitation power supply, is output to the main circuit output terminal through the ninth diode D9, and charges the second capacitor C2; according to the rotor position information, when the first phase winding M needs to stop working, the first switch K1, the fourth switch K4, the tenth switch K10, and the thirteenth switch K13 are disconnected, and the first phase winding M ends its work;
[0044] The operation of the second phase winding N and the third phase winding P is similar to that of the first phase winding M. According to the rotor position information, when the second phase winding N is working, only the second switch K2 needs to replace the first switch K1, the fifth switch K5 needs to replace the fourth switch K4, the eleventh switch K11 needs to replace the tenth switch K10, and the fourteenth switch K14 needs to replace the thirteenth switch K13. According to the rotor position information, when the third phase winding P is working, only the third switch K3 needs to replace the first switch K1, the sixth switch K6 needs to replace the fourth switch K4, the twelfth switch K12 needs to replace the tenth switch K10, and the fifteenth switch K15 needs to replace the thirteenth switch K13.
[0045] Example 2 of the main circuit control method: When the switched reluctance motor operates as a motor, the power supply circuit outputs electrical energy as the power supply for each phase winding of the main circuit. According to the rotor position information, when the first phase winding M needs to be put into operation, the first switch K1, the fourth switch K4, the seventh switch K7, the eighth switch K8, the tenth switch K10, and the thirteenth switch K13 are closed and turned on, entering the first working stage of the first phase winding M, that is, the main stage of motor operation. The energy flow diagram is attached. Figure 3As shown, the power supply circuit supplies power to each branch of the first phase winding M, while the first capacitor C1 is charged. The output of the main circuit is maintained by the second capacitor C2. The first switch K1, the first branch of the first phase winding M1, and the branch of the third diode D3 are connected in parallel with the branch of the first diode D1, the fourth switch K4, and the second branch of the first phase winding M2. The voltage of each branch is equal to the output voltage of the power supply circuit. The third branch of the first phase winding M3, the tenth switch K10, and the sixth diode D6, and... The branches of the eighth diode D8, the fourth branch of the first phase winding M4, and the thirteenth switch K13 are connected in parallel. The voltage of each branch is equal to the output voltage of the power supply circuit. That is, all four branches of the first phase winding M are connected in parallel. If the voltage drop of the transistors is ignored, the terminal voltage of each branch of the first phase winding M is equal to the output voltage of the power supply circuit. According to the rotor position information, when the first phase winding M needs to be terminated, the seventh switch K7 and the eighth switch K8 are first disconnected, allowing the energy stored in each branch of the first phase winding M to be as shown in the attached figure. Figure 5 As shown, the current is released to the main circuit output terminal. When the current drops to zero or the next phase winding is about to be put into operation, the first switch K1, the fourth switch K4, the tenth switch K10, and the thirteenth switch K13 are disconnected, and the operation of the first phase winding M ends.
[0046] The operation of the second phase winding N and the third phase winding P is similar to that of the first phase winding M. According to the rotor position information, when the second phase winding N is working, only the second switch K2 needs to replace the first switch K1, the fifth switch K5 needs to replace the fourth switch K4, the eleventh switch K11 needs to replace the tenth switch K10, and the fourteenth switch K14 needs to replace the thirteenth switch K13. According to the rotor position information, when the third phase winding P is working, only the third switch K3 needs to replace the first switch K1, the sixth switch K6 needs to replace the fourth switch K4, the twelfth switch K12 needs to replace the tenth switch K10, and the fifteenth switch K15 needs to replace the thirteenth switch K13.
[0047] The power supply circuit control method uses the sixteenth switch, K16, as the only controllable switch. It operates in high-frequency PWM mode, therefore the power supply circuit has two operating phases. The first phase occurs when the sixteenth switch, K16, is closed and conducting, as shown in the attached diagram. Figure 6 As shown, the tenth diode D10 and the thirteenth diode D13 are reverse-biased and cut off. The input power from the isolation converter charges the first inductor L1 and the third capacitor C3, while the fourth capacitor C4 and the fifth capacitor C5 discharge. The sixth capacitor C6, the seventh capacitor C7, the second inductor L2, and the third inductor L3 are charged. The output side of the power supply circuit is maintained by the eighth capacitor C8. When the sixteenth switch K16 is turned off, the second operating stage begins, as shown in the attached diagram. Figure 7As shown, the tenth diode D10 and the thirteenth diode D13 are turned on, receiving input electrical energy and outputting it. In the first working stage, all the charged components are discharged, and the discharged components are charged. According to the volt-second balance principle of the second inductor L2 and the third inductor L3 in one switching cycle of the sixteenth switch K16, we can obtain:
[0048]
[0049] In equation (2), U0 is the output voltage of the power supply circuit; U b α is the output voltage of the power supply circuit isolation converter; α is the PWM duty cycle of the sixteenth switch K16.
[0050] It can be seen that when the PWM duty cycle of the sixteenth switch K16 is adjusted, the output voltage of the power supply circuit will change, and it can be seen from equation (2) that α needs to be adjustable within the range of 0 to 0.5.
[0051] Based on the overall voltage relationship, i.e., the range, the variable voltage function of the isolation converter can be set, so the input voltage of the power supply circuit is not necessarily equal to the output voltage of the isolation converter.
[0052] From the appendix of this embodiment Figure 1 As can be seen from the structure, for any four-branch phase winding structure of a switched reluctance motor, in the case of non-three-phase winding, only the branch windings and the branch of the series switch tube need to be added or removed. Therefore, this invention is necessarily within the protection scope for non-three-phase four-branch switched reluctance motors.
Claims
1. A four-branch transformer freewheeling direct-drive switched reluctance motor converter, consisting of a main circuit and a power supply circuit, characterized in that the output terminals of the main circuit are connected to the input terminals of the power supply circuit, and the output terminals of the power supply circuit are connected to the input terminals of the main circuit.
2. The four-branch transformer-driven freewheeling DC switched reluctance motor converter according to claim 1, the main circuit includes: The technical features of the following switching transistors are: first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, and fifteenth; first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth diodes; first capacitor; second capacitor; first branch winding of first phase winding; second branch winding of first phase winding; third branch winding of first phase winding; fourth branch winding of first phase winding; first branch winding of second phase winding; second branch winding of second phase winding; third branch winding of second phase winding; fourth branch winding of second phase winding; first branch winding of third phase winding; second branch winding of third phase winding; third branch winding of third phase winding; and fourth branch winding of third phase winding. The anode of the first switch is connected to the anodes of the second and third switches, the anode of the first diode, and the anode of the fourth diode, and serves as the positive input terminal of the main circuit. The cathode of the first switch is connected to one end of the first branch winding of the first phase winding. The cathode of the second switch is connected to one end of the first branch winding of the second phase winding. The cathode of the third switch is connected to one end of the first branch winding of the third phase winding. The other end of the first branch winding of the first phase winding is connected to the other end of the first branch winding of the second phase winding, the other end of the first branch winding of the third phase winding, the anode of the second diode, and the anode of the third diode. The cathode of the second diode is connected to the cathode of the first diode and the anode of the fourth switch. The anodes of the fifth and sixth switching transistors, and the cathode of the fourth switching transistor are connected to one end of the second branch winding of the first phase winding, the cathode of the fifth switching transistor is connected to one end of the second branch winding of the second phase winding, and the cathode of the sixth switching transistor is connected to one end of the second branch winding of the third phase winding. The other end of the second branch winding of the first phase winding is connected to the other end of the second branch winding of the second phase winding, the other end of the second branch winding of the third phase winding, the cathode of the third diode, the anode of the seventh switching transistor, the anode of the fifth diode, and one end of the first capacitor. The other end of the first capacitor is connected to the cathode of the fourth diode, the anode of the eighth switching transistor, and the anode of the ninth diode. The cathode of the eighth switching transistor is connected to the anode of the first... The circuit consists of the cathode of the ninth switch, the anode of the eighth diode, one end of the second capacitor, one end of the third branch winding of the first phase winding, one end of the third branch winding of the second phase winding, and one end of the third branch winding of the third phase winding, which serves as the negative terminal of the main circuit output. The other end of the third branch winding of the first phase winding is connected to the anode of the tenth switch, the other end of the third branch winding of the second phase winding is connected to the anode of the eleventh switch, and the other end of the third branch winding of the third phase winding is connected to the anode of the twelfth switch. The cathode of the tenth switch is connected to the cathodes of the eleventh and twelfth switches, the anode of the sixth diode, and the anode of the seventh diode. The cathode of the seventh diode is connected to the cathode of the eighth diode. One end of the fourth branch winding of the first phase winding, one end of the fourth branch winding of the second phase winding, and one end of the fourth branch winding of the third phase winding are connected to the anode of the thirteenth switch transistor. The other end of the fourth branch winding of the first phase winding is connected to the anode of the fourteenth switch transistor. The other end of the fourth branch winding of the third phase winding is connected to the anode of the fifteenth switch transistor. The cathode of the thirteenth switch transistor is connected to the cathodes of the fourteenth, fifteenth, sixth, and seventh switches transistors and serves as the negative input terminal of the main circuit. The anode of the ninth switch transistor is connected to the cathode of the fifth diode. The cathode of the ninth diode is connected to the other end of the second capacitor and serves as the positive output terminal of the main circuit.The first phase winding consists of the first branch winding, the second branch winding, the third branch winding, and the fourth branch winding of the first phase winding. The second phase winding consists of the first branch winding, the second branch winding, the third branch winding, and the fourth branch winding of the second phase winding. The third phase winding consists of the first branch winding, the second branch winding, the third branch winding, and the fourth branch winding of the third phase winding.
3. The four-branch transformer freewheeling DC-DC switched reluctance motor converter according to claim 1, wherein the power supply circuit includes: The sixteenth switch, tenth diode, eleventh diode, twelfth diode, thirteenth diode, third capacitor, fourth capacitor, fifth capacitor, sixth capacitor, seventh capacitor, eighth capacitor, first inductor, second inductor, third inductor, and isolation converter, are characterized by the following: The positive input terminal of the isolation converter is connected to the positive output terminal of the main circuit as the positive input terminal of the power supply circuit. The negative input terminal of the isolation converter is connected to the negative output terminal of the main circuit as the negative input terminal of the power supply circuit. The positive output terminal of the isolation converter is connected to one end of the first inductor. The other end of the first inductor is connected to the anode of the tenth diode and one end of the third capacitor. The cathode of the tenth diode is connected to the anode of the eleventh diode, one end of the fourth capacitor, and one end of the second inductor. The cathode of the eleventh diode is connected to the anode of the thirteenth diode and one end of the sixth capacitor. The other end of the sixth capacitor is connected to the anode of the sixteenth switch and the... The cathode of the thirteenth diode is connected to one end of the fifth capacitor and the other end of the second inductor. It is connected to one end of the eighth capacitor and serves as the positive output terminal of the power supply circuit, which is connected to the positive input terminal of the main circuit. The cathode of the sixteenth switch is connected to the other end of the fourth capacitor, one end of the seventh capacitor, and one end of the third inductor. The other end of the seventh capacitor is connected to the anode of the twelfth diode and serves as the negative output terminal of the power supply circuit, which is connected to the negative input terminal of the main circuit. The cathode of the twelfth diode is connected to the other end of the third capacitor, the other end of the fifth capacitor, the other end of the third inductor, and the negative output terminal of the isolation converter. The isolation converter is a magnetically isolated DC / DC converter.
4. The control method for the four-branch transformer-driven freewheeling switched reluctance motor converter according to claims 1 and 2, specifically the main circuit control method, wherein when the switched reluctance motor operates as a generator, the power supply circuit outputs electrical energy as the excitation power supply for each phase winding of the main circuit, its technical feature is that... According to the rotor position information, when the first phase winding needs to be put into operation, the first, fourth, seventh, eighth, tenth and thirteenth switches are closed and turned on, and the first phase winding enters the first working stage, namely the excitation stage. The excitation power supply supplies power to each branch winding of the first phase winding for excitation. At the same time, the first capacitor is charged, and the output of the main circuit is maintained by the second capacitor. Based on the rotor position information, when the excitation stage needs to end, the seventh and eighth switches are turned off. If the ninth switch is closed at this time, the first phase winding enters the second working stage, which is the half-voltage freewheeling stage where the first phase winding releases its stored energy. Each branch winding of the first phase winding forms a closed loop with the input excitation power supply, and the voltage of each branch winding is half of the excitation power supply voltage. When the second working stage, i.e., the half-voltage freewheeling stage, needs to end, the ninth switch is turned off, and the first phase winding enters the third working stage, i.e., the power generation stage. If the second working stage is not needed, the ninth switch does not need to be closed at the end of the excitation stage, and the power generation stage is directly entered. After the four branch windings of the first phase winding are connected in series, their stored energy, together with the excitation power supply, is output to the main circuit output terminal through the ninth diode and charges the second capacitor. Based on the rotor position information, when the first phase winding needs to end its operation, the first, fourth, tenth, and thirteenth switches are turned off, and the first phase winding operation ends. Based on the rotor position information, when the second phase winding needs to be put into operation, compared to the operation process of the first phase winding, only the second switch transistor needs to replace the first switch transistor, the fifth switch transistor needs to replace the fourth switch transistor, the eleventh switch transistor needs to replace the tenth switch transistor, and the fourteenth switch transistor needs to replace the thirteenth switch transistor, with the rest being the same; based on the rotor position information, when the third phase winding needs to be put into operation, compared to the operation process of the first phase winding, only the third switch transistor needs to replace the first switch transistor, the sixth switch transistor needs to replace the fourth switch transistor, the twelfth switch transistor needs to replace the tenth switch transistor, and the fifteenth switch transistor needs to replace the thirteenth switch transistor, with the rest being the same.
5. The control method for the four-branch transformer-driven freewheeling switched reluctance motor converter according to claims 1 and 2, the main circuit control method, wherein when the switched reluctance motor operates as a motor, the power supply circuit outputs electrical energy as the power supply for each phase winding of the main circuit, its technical feature is that... According to the rotor position information, when the first phase winding needs to be put into operation, the first, fourth, seventh, eighth, tenth and thirteenth switch tubes are closed and turned on first, and the first working stage of the first phase winding, namely the main stage of electric operation, is entered. The power supply circuit supplies power to each branch winding of the first phase winding, and the first capacitor is charged at the same time. The output of the main circuit is maintained by the second capacitor. According to the rotor position information, when the first phase winding is about to finish working, the seventh and eighth switches are disconnected first, and the energy stored in each branch winding of the first phase winding is released to the main circuit output. When the next phase winding is about to start working according to the rotor position information, the first, fourth, tenth, and thirteenth switches are disconnected, and the first phase winding finishes working. Based on the rotor position information, when the second phase winding needs to be put into operation, compared to the operation process of the first phase winding, only the second switch transistor needs to replace the first switch transistor, the fifth switch transistor needs to replace the fourth switch transistor, the eleventh switch transistor needs to replace the tenth switch transistor, and the fourteenth switch transistor needs to replace the thirteenth switch transistor, with the rest being the same; based on the rotor position information, when the third phase winding needs to be put into operation, compared to the operation process of the first phase winding, only the third switch transistor needs to replace the first switch transistor, the sixth switch transistor needs to replace the fourth switch transistor, the twelfth switch transistor needs to replace the tenth switch transistor, and the fifteenth switch transistor needs to replace the thirteenth switch transistor, with the rest being the same.
6. The control method for the four-branch transformer freewheeling DC-DC switched reluctance motor converter according to claims 1 and 3, and the control method for the power supply circuit, are characterized by the following technical features: The sixteenth switch operates in PWM mode. The power supply circuit has two operating phases. In the first operating phase, when the sixteenth switch is closed and turned on, the tenth and thirteenth diodes are reverse-biased and cut off. The input power through the isolation converter charges the first inductor and the third capacitor, while the fourth and fifth capacitors discharge. The sixth, seventh, second, and third inductors are charged, and the output side of the power supply circuit is maintained by the eighth capacitor. When the sixteenth switch is turned off, the second working stage begins. The tenth and thirteenth diodes turn on, receiving and outputting input power. In the first working stage, all the charged components discharge, and the discharged components are charged. When the PWM duty cycle of the sixteenth switch K16 is adjusted, the output voltage of the power supply circuit will change.