Switched reluctance motor five-level power converter capable of simplifying number of switching tubes

Abstract

The invention discloses a switch reluctance motor five-level power converter capable of simplifying the number of switch tubes, which belongs to the technical field of switch reluctance motor control and comprises an energy storage capacitor module, a switch tube module of each of three phases and common phases, a transverse switch tube module and a diode module. A common phase is added under the traditional three-phase condition, each phase and the common phase are connected with an inductor to simplify a bridge arm, a full-bridge structure is used for replacing an asymmetric half-bridge, the use of diodes is reduced, meanwhile, the number of switching tubes of each phase is reduced, and five-level output of the circuit is achieved through the common phase; meanwhile, a six-module IGBT can be used as a three-phase switch tube, a double-module IGBT can be used as a common phase, and a diode module can be used as a switch tube led out from the midpoint of the capacitor, so that the number of required single modules is greatly reduced, the control method can be simplified, the reliability is higher, and the switching loss is smaller.

Description

Technical Field

[0001] The invention belongs to the technical field of switched reluctance motor control, and in particular relates to a switched reluctance motor five-level power converter with a simplified number of switch tubes. Background Art

[0002] In recent years, with the rapid development of human society, environmental issues have become an increasingly important topic internationally. Carbon emissions from fuel vehicles are one of the top priorities. With the rapid increase in the number of cars in my country, automobile emissions have also brought huge problems to the environment. In order to optimize the structure of traditional energy, the research and development of new energy has long-term significance. The emergence of new energy vehicles is an application of new energy. Pure electric vehicles have gradually become the mainstream of research and promotion because they only use electrical energy and do not require complex transmission devices and engines, and they do not produce gaseous pollutants.

[0003] The carbon brushes and slip rings of the DC motor increase the size of the motor, thereby increasing the cost of the motor. The induction asynchronous motor has a simple structure, is relatively strong and low cost, but has serious heating problems at high speeds. The power density, energy conversion rate and peak efficiency of the permanent magnet synchronous motor are relatively high. It is more energy-efficient and has higher operating reliability when used in electric vehicles. However, since the permanent magnets of the motor rotor are affected by temperature and vibration, there may be a risk of magnetism fading. When the motor works in a harsh environment, the motor rotor is prone to failure and the cost of regular maintenance is high. Permanent magnet motors are affected by permanent magnet rare earth materials and have relatively high costs. At the same time, the production process level of permanent magnet materials leads to a small power range of the motor.

[0004] The switched reluctance motor drive system is another drive solution for electric vehicles. The structure of the switched reluctance motor is relatively simple. The stator and rotor are both made of laminated silicon steel sheets. There is no permanent magnet, and it has strong anti-disturbance ability and low manufacturing cost. At the same time, it also has high torque density and power density, good speed regulation performance, strong overload capacity, and a wider speed regulation range than permanent magnet synchronous motors. Compared with other motor drivers, the switched reluctance motor has high controllability. The motor winding current and torque direction are not related. Forward and reverse rotation, it only needs to set the conduction sequence of each phase of the motor. The concentrated winding is only on the stator, and the rotor has no heat dissipation requirements. Even if the motor works at a high temperature, the excess heat on the winding can be quickly discharged through the casing and fan. The research on the switched reluctance motor drive system mainly includes the research on power converters, motor torque pulsation, and position sensors. Among them, the power converter is the brain of the switched reluctance motor drive system, which can control the motor operation state after comprehensively considering factors such as motor speed, rotor position, and winding phase current.

[0005] At present, the conventional drive system of the switched reluctance motor uses a conventional asymmetric half-bridge power converter, which is a three-level power converter. The topology diagram of the conventional asymmetric half-bridge power converter is as follows: Figure 7-10 As shown. Each phase of the motor is composed of a switch tube and a diode to form a circuit. The phases are independent of each other. By controlling the switch tube to turn off, the power converter can switch between different modes. The control method is simple. However, the output voltage of each phase of the traditional asymmetric half-bridge has only three states: 1, 0, and -1. The output voltage is relatively single and cannot meet the requirements of high-precision control, multiple selectivity, and high fault tolerance in most scenarios. And there is only one option for excitation and demagnetization, which cannot control the motor torque more deeply. Figure 11-Figure 16 A five-level power converter is proposed. It realizes the output of five levels by turning on and off four switch tubes in each phase, and each phase is independent. However, it can be seen that the number of switch tubes and diodes in each phase is large, and the number of switch tubes in five states is also large, and the switching loss is large. Moreover, there is no ready-made modularization of the switch tubes and diodes in each phase, and the required number cannot be reduced, which cannot meet the principle of simplest design. More switch tubes and diodes will also increase the switching loss and affect the efficiency of the motor. For the control of five levels, more switch tubes mean more complex control methods and more difficulty in achieving better control results. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides a five-level power converter of a switched reluctance motor with a simplified number of switch tubes. The use of diodes is reduced by using a full-bridge circuit, and the number of switch tubes per phase is reduced. The five-level output of the circuit is realized through a common phase. At the same time, the three-phase switch tubes can use six-module IGBTs, the common phase can use a two-module IGBT, and the midpoint of the two capacitor connections can lead to a three-phase lateral switch tube, which greatly reduces the number of required single modules, can realize a simplified control method, has higher reliability, and has lower switching losses, and solves the problem in the prior art that the three-level control cannot meet the voltage diversity, high fault tolerance of motor control, high precision, and diversified selection of excitation and demagnetization, as well as the problem of redundant use of switch tubes and diodes in the existing five-level control.

[0007] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is: a five-level power converter of a switched reluctance motor with a simplified number of switch tubes, including an energy storage capacitor module, a switch tube module for each phase of the three phases and the common phase, a lateral switch tube module and a diode module; The switch tube module of each phase of the three phases and the common phase includes a first switch tube and a second switch tube connected in series with the power supply, the collector tube of the first switch tube is connected to the positive electrode of the power supply, the emitter of the first switch tube serves as the midpoint of the switch tube module and is connected to the collector of the second switch tube, and the emitter of the second switch tube is connected to the negative electrode of the power supply; The midpoint of each of the three-phase switch tube modules is connected to the midpoint of the common phase switch tube module through a corresponding inductor; The lateral switch tube module of each phase in the three phases and the common phase is provided with a third switch tube, and the diode module of each phase in the three phases and the common phase is provided with a first diode, the anode of the first diode is connected to the midpoint of the energy storage capacitor module, the cathode of the first diode is connected to the collector of the third switch tube of the corresponding phase, and the emitter of the third switch tube is connected to the midpoint of the switch tube module of the corresponding phase; The energy storage capacitor module includes two groups of energy storage capacitors connected in series with a power supply, and the connection point of the two groups of energy storage capacitors serves as the midpoint of the energy storage capacitor module.

[0008] Furthermore: one capacitor is provided in each group of the energy storage capacitors.

[0009] Furthermore, the first switch tube, the second switch tube, and the third switch tube are all IGBTs.

[0010] Furthermore: the first switch tube, the second switch tube, and the third switch tube in the three phases all use six-module IGBTs, and the first switch tube, the second switch tube, and the third switch tube in the common phase all use double-module IGBTs.

[0011] Furthermore: a second diode is arranged between the collector and emitter of the first switch tube, the second switch tube and the third switch tube, wherein the anode of the second diode is connected to the emitter of the corresponding switch tube, and the cathode of the second diode is connected to the collector of the corresponding switch tube.

[0012] The beneficial effects of the present invention are as follows: the present invention provides a five-level power converter of a switched reluctance motor with a simplified number of switch tubes, by adding a common phase in the case of a traditional three-phase, simplifying the bridge arm by connecting an inductor between each phase and the common phase, and using a full-bridge structure instead of an asymmetric half-bridge, reducing the use of diodes, while reducing the number of switch tubes per phase, and realizing a five-level output of the circuit through a common phase; at the same time, the switch tubes of the three phases can use six-module IGBTs, the common phase can use double-module IGBTs, and the switch tubes led out of the midpoint of the capacitor can use diode modules, which greatly reduces the number of single modules required, can realize a simplified control method, higher reliability, and smaller switching losses. In addition, since it is no longer a single-level excitation and demagnetization, the speed of the winding excitation and demagnetization can be changed to a certain extent, which is convenient for more in-depth control. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The present invention is a schematic circuit diagram of a five-level power converter of a switched reluctance motor with a simplified number of switch tubes.

[0014] Figure 2 A fast excitation state circuit diagram of a switched reluctance motor five-level power converter with a simplified number of switch tubes of the present invention.

[0015] Figure 3 A normal excitation state circuit diagram of a switched reluctance motor five-level power converter with a simplified number of switch tubes of the present invention.

[0016] Figure 4 A zero-voltage freewheeling state circuit diagram of a switched reluctance motor five-level power converter with a simplified number of switch tubes of the present invention.

[0017] Figure 5 A normal demagnetization state circuit diagram of a switched reluctance motor five-level power converter with a simplified number of switch tubes of the present invention.

[0018] Figure 6 The invention discloses a fast demagnetization state circuit of a switched reluctance motor five-level power converter with a simplified number of switch tubes.

[0019] Figure 7 Schematic diagram of the circuit of a three-level power converter of a switched reluctance motor in the prior art.

[0020] Figure 8 Circuit diagram of the excitation state of a three-level power converter of a switched reluctance motor in the prior art.

[0021] Fig. 9 Circuit diagram of zero-voltage freewheeling state of a three-level power converter of a switched reluctance motor in the prior art.

[0022] Fig.10 Circuit diagram of demagnetization state of a three-level power converter of a switched reluctance motor in the prior art.

[0023] Fig.11 Schematic diagram of the circuit of a five-level converter of a switched reluctance motor in the prior art.

[0024] Fig.12 Circuit diagram of the fast excitation state of a five-level power converter of a switched reluctance motor in the prior art.

[0025] Fig.13 Circuit diagram of a normal excitation state of a five-level power converter of a switched reluctance motor in the prior art.

[0026] Fig.14 Circuit diagram of the zero-voltage freewheeling state of a five-level power converter of a switched reluctance motor in the prior art.

[0027] Fig.15 Circuit diagram of a normal demagnetization state of a five-level power converter of a switched reluctance motor in the prior art.

[0028] Fig.16 Prior art switched reluctance motor five-level power converter fast demagnetization state circuit. DETAILED DESCRIPTION

[0029] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0030] like Figure 1-Figure 6 As shown, in one embodiment of the present invention, a switched reluctance motor five-level power converter with a simplified number of switch tubes includes an energy storage capacitor module, a switch tube module for each phase of the three phases and the common phase, a lateral switch tube module and a diode module; The switch tube module of each phase of the three phases and the common phase includes a first switch tube and a second switch tube connected in series with the power supply, the collector tube of the first switch tube is connected to the positive electrode of the power supply, the emitter of the first switch tube serves as the midpoint of the switch tube module and is connected to the collector of the second switch tube, and the emitter of the second switch tube is connected to the negative electrode of the power supply; The midpoint of each of the three-phase switch tube modules is connected to the midpoint of the common phase switch tube module through a corresponding inductor; In this embodiment, the three phases are represented by phase A, phase B, and phase C, and the common phase is represented by common phase S.

[0031] The switch tube module of phase A is composed of switch tube A1 and switch tube A2 connected in series and located between the positive and negative poles of an external power supply, wherein the collector of switch tube A1 is connected to the positive pole of the power supply, the emitter of switch tube A1 is connected to the collector of switch tube A2, and the emitter of switch tube A2 is connected to the negative pole of the power supply.

[0032] The switch tube module of phase B is composed of switch tube B1 and switch tube B2 connected in series and located between the positive and negative poles of the external power supply, wherein the collector of switch tube B1 is connected to the positive pole of the power supply, the emitter of switch tube B1 is connected to the collector of switch tube B2, and the emitter of switch tube B2 is connected to the negative pole of the power supply.

[0033] The switch tube module of phase C is composed of switch tube C1 and switch tube C2 connected in series and located between the positive and negative poles of an external power supply, wherein the collector of switch tube C1 is connected to the positive pole of the power supply, the emitter of switch tube C1 is connected to the collector of switch tube C2, and the emitter of switch tube C2 is connected to the negative pole of the power supply.

[0034] The switch tube module of the common phase S is composed of a switch tube S1 and a switch tube S2 connected in series and located between the positive and negative poles of an external power supply, wherein the collector of the switch tube S1 is connected to the positive pole of the power supply, the emitter of the switch tube S1 is connected to the collector of the switch tube S2, and the emitter of the switch tube S2 is connected to the negative pole of the power supply.

[0035] The midpoints of the switches A1 and A2, B1 and B2, C1 and C2 and S1 and S2 are connected to the midpoints of the switches S1 and S2 through inductors L. ph connect.

[0036] The lateral switch tube module of each phase in the three phases and the common phase is provided with a third switch tube, and the diode module of each phase in the three phases and the common phase is provided with a first diode, the anode of the first diode is connected to the midpoint of the energy storage capacitor module, the cathode of the first diode is connected to the collector of the third switch tube of the corresponding phase, and the emitter of the third switch tube is connected to the midpoint of the switch tube module of the corresponding phase; In this embodiment, the lateral switch tube and diode module of phase A is composed of a switch tube A3 and a diode D1; the anode of the diode D1 is connected to the midpoint of the energy storage capacitors Cdc1 and Cdc2, the cathode of the diode D1 is connected to the collector of the switch tube A3, and the emitter of the switch tube A3 is connected to the midpoint of the switch tube A1 and the switch tube A2.

[0037] The horizontal switch tube and diode module of phase B is composed of a switch tube B3 and a diode D2; the anode of the diode D2 is connected to the midpoint of the energy storage capacitors Cdc1 and Cdc2, the cathode of the diode D2 is connected to the collector of the switch tube B3, and the emitter of the switch tube B3 is connected to the midpoint of the switch tubes B1 and B2.

[0038] The C-phase lateral switch tube and diode module is composed of a switch tube C3 and a diode D3; the anode of the diode D3 is connected to the midpoint of the energy storage capacitors Cdc1 and Cdc2, the cathode of the diode D3 is connected to the collector of the switch tube C3, and the emitter of the switch tube C3 is connected to the midpoint of the switch tubes C1 and C2.

[0039] The lateral switch tube and diode module of the common phase S is composed of a switch tube S3 and a diode D4; the anode of the diode D4 is connected to the midpoint of the energy storage capacitors Cdc1 and Cdc2, the cathode of the diode D4 is connected to the collector of the switch tube S3, and the emitter of the switch tube S3 is connected to the midpoint of the switch tubes S1 and S2.

[0040] The energy storage capacitor module includes two groups of energy storage capacitors connected in series with a power supply, and the connection point of the two groups of energy storage capacitors serves as the midpoint of the energy storage capacitor module.

[0041] In this embodiment, the energy storage capacitor module is divided into two groups of energy storage capacitors Cdc1 and Cdc2. The two groups of energy storage capacitors are connected in series and then connected between the positive and negative electrodes of the external power supply.

[0042] One capacitor is provided in each group of the energy storage capacitors.

[0043] In this embodiment, the energy storage capacitor module is divided into two groups of energy storage capacitors Cdc1 and Cdc2. The two groups of energy storage capacitors are connected in series and then connected between the positive and negative electrodes of the external power supply.

[0044] The models of the first switch tube, the second switch tube and the third switch tube are all IGBT.

[0045] The first switch tube, the second switch tube, and the third switch tube in the three phases all use six-module IGBTs, and the first switch tube, the second switch tube, and the third switch tube in the common phase all use double-module IGBTs.

[0046] In this embodiment, all switch tubes are IGBTs, wherein the switch tubes of the three phases A, B, and C are six-module IGBTs, and the switch tubes in the common phase are two-module IGBTs.

[0047] A second diode is arranged between the collector and emitter of the first switch tube, the second switch tube and the third switch tube, wherein the anode of the second diode is connected to the emitter of the corresponding switch tube, and the cathode of the second diode is connected to the collector of the corresponding switch tube.

[0048] In this embodiment, a diode is connected between the collector and emitter of all the switch tubes, wherein the anode of the diode is connected to the emitter of the corresponding switch tube, and the cathode of the diode is connected to the collector of the corresponding switch tube.

[0049] The working principle of a five-level power converter of a switched reluctance motor with a simplified number of switch tubes provided by the present invention is as follows: Since the structures of the three phases of the switched reluctance motor are completely the same, the present invention analyzes one of the phases to replicate the output state of the three phases.

[0050] like Figure 2 As shown in the figure, when the switch tubes A1 and S2 are both turned on and the diodes are both turned off, the current flows from the positive pole of the power supply through the switch tube A1 to the switched reluctance motor (inductor L ph is the inductance value of each phase of the switched reluctance motor), and then flows from the switch tube S2 to the negative pole of the power supply. At this time, a high voltage U is applied to the winding. DC Excitation, to achieve rapid excitation, the switch state is "+2".

[0051] like Figure 3 As shown in the figure, when the switch tubes A3 and S2 are both turned on, the diode D1 is turned on, and the current direction is from the midpoint of the capacitors C1 and C2 through the diode D1, through the switch tube A3, then through the switched reluctance motor, and then from the switch tube S2 to the negative pole of the power supply. At this time, a low voltage of 0.5U is applied to the winding. DC Excitation, realize excitation, the switch state is "+1".

[0052] like Figure 4 As shown, when the switch tube S2 is turned on, the current direction is from the diode of the switch tube A2, through the switched reluctance motor, and then through the switch tube S2 to the switch tube A2. At this time, it is a zero-voltage freewheeling state and the switch state is "0".

[0053] like Figure 5 As shown in the figure, when the switch tube A3 is turned on, the current flows from the midpoint of capacitors C1 and C2 through diode D1, through switch tube A3, and then through the switched reluctance motor, and then flows from the diode of switch tube S1 to the positive pole of the power supply, feeding the electric energy back to capacitor Cdc1. At this time, it is in the demagnetization state, and the switch state is "-1".

[0054] like Figure 6 As shown, when the switches are all turned off, the current flows from the diode of switch A2 to the switched reluctance motor and then feeds back electrical energy from the diode of switch S1 to capacitors Cdc1 and Cdc2. This is a fast demagnetization state, and the switch state is "-2".

[0055] Among the five states mentioned above, there is only one switch tube and diode state corresponding to the "+2" state of rapid excitation and the "-2" state of rapid demagnetization, while there are multiple switch states for normal excitation demagnetization and zero-voltage freewheeling. Different corresponding switch states can be formulated according to needs, so that the switch thermal balance of the entire system can reach a better level. At the same time, a variety of switch state options also make it possible to meet the required switch state through other switch states when a switch tube is damaged, which also increases the stability of the system to a certain extent.

[0056] The multi-level levels of the power converter proposed in the present invention can meet the low-speed and high-speed requirements of the switched reluctance motor. During normal operation, it can mainly work in the three working states of "+1", "0" and "-1" to meet the general working conditions. In the high-speed stage, the fast excitation mode is used to overcome the large back electromotive force to quickly establish the current; in the demagnetization stage, the fast demagnetization mode is used for rapid demagnetization to suppress the tail current and improve the motor output and operating efficiency. At the same time, the proposed power converter uses fewer switching tubes and diodes than the five-level power converter in the prior art, reduces switching losses, and improves the utilization rate of the device. The multi-level advantages of the multi-level power circuit can also be used to effectively reduce torque pulsation and improve the dynamic response of the motor.

[0057] The beneficial effects of the present invention are as follows: the present invention provides a five-level power converter of a switched reluctance motor with a simplified number of switch tubes, by adding a common phase in the case of a traditional three-phase, simplifying the bridge arm by connecting an inductor between each phase and the common phase, and using a full-bridge structure instead of an asymmetric half-bridge, reducing the use of diodes, while reducing the number of switch tubes per phase, and realizing a five-level output of the circuit through a common phase; at the same time, the switch tubes of the three phases can use six-module IGBTs, the common phase can use double-module IGBTs, and the switch tubes led out of the midpoint of the capacitor can use diode modules, which greatly reduces the number of single modules required, can realize a simplified control method, higher reliability, and smaller switching losses. In addition, since it is no longer a single-level excitation and demagnetization, the speed of the winding excitation and demagnetization can be changed to a certain extent, which is convenient for more in-depth control.

[0058] In the description of the present invention, it is necessary to understand that the orientation or positional relationship indicated by the terms "center", "thickness", "upper", "lower", "horizontal", "top", "bottom", "inner", "outer", "radial", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", and "third" are used only for descriptive purposes, and cannot be understood as indicating or implying the relative importance or the number of implicitly specified technical features. Therefore, the features defined by "first", "second", and "third" may explicitly or implicitly include one or more of the features.

Claims

1. A five-level power converter of a switched reluctance motor with a simplified number of switch tubes, characterized in that: It includes energy storage capacitor module, switch tube module of each phase in three phases and common phase, lateral switch tube module and diode module; The switch tube module of each phase of the three phases and the common phase includes a first switch tube and a second switch tube connected in series with the power supply, the collector tube of the first switch tube is connected to the positive electrode of the power supply, the emitter of the first switch tube serves as the midpoint of the switch tube module and is connected to the collector of the second switch tube, and the emitter of the second switch tube is connected to the negative electrode of the power supply; The midpoint of each of the three-phase switch tube modules is connected to the midpoint of the common phase switch tube module through a corresponding inductor; The lateral switch tube module of each phase in the three phases and the common phase is provided with a third switch tube, and the diode module of each phase in the three phases and the common phase is provided with a first diode, the anode of the first diode is connected to the midpoint of the energy storage capacitor module, the cathode of the first diode is connected to the collector of the third switch tube of the corresponding phase, and the emitter of the third switch tube is connected to the midpoint of the switch tube module of the corresponding phase; The energy storage capacitor module includes two groups of energy storage capacitors connected in series with a power supply, and the connection point of the two groups of energy storage capacitors serves as the midpoint of the energy storage capacitor module.

2. The switched reluctance motor five-level power converter with simplified number of switch tubes according to claim 1, characterized in that: One capacitor is provided in each group of the energy storage capacitors.

3. The switched reluctance motor five-level power converter with simplified number of switch tubes according to claim 1, characterized in that: The models of the first switch tube, the second switch tube and the third switch tube are all IGBT.

4. The switched reluctance motor five-level power converter with simplified number of switch tubes according to claim 3, characterized in that: The first switch tube, the second switch tube, and the third switch tube in the three phases all use six-module IGBTs, and the first switch tube, the second switch tube, and the third switch tube in the common phase all use double-module IGBTs.

5. The switched reluctance motor five-level power converter with simplified number of switch tubes according to claim 1, characterized in that: A second diode is arranged between the collector and emitter of the first switch tube, the second switch tube and the third switch tube, wherein the anode of the second diode is connected to the emitter of the corresponding switch tube, and the cathode of the second diode is connected to the collector of the corresponding switch tube.

Images