A five-level power converter for switched reluctance motors used in hybrid vehicles

Abstract

The present invention discloses a five-level power converter for a switched reluctance motor used in the field of hybrid vehicles. The intermediate level is realized by adding a transverse switch tube module and a transverse diode module to the traditional three-phase case, so as to achieve multi-level output. Based on the connection relationship between the switch tube module, the diode module, the transverse switch tube module and the transverse diode module of each phase in the three-phase, five different states of the output voltage of the switched reluctance motor are realized by turning on and off the two switch tubes of each phase and the transverse switch tube, thereby improving the flexibility of the motor. At the same time, since the excitation and demagnetization of the winding are no longer a single level, the speed of the excitation and demagnetization of the winding can be changed to a certain extent, which is convenient for more in-depth control, and solves the problem that the existing three-level cannot meet the voltage diversity, high fault tolerance and high precision of the motor control, and the diversified selection of excitation and demagnetization, as well as the redundant use of the existing multi-level switch tubes and diodes.

Description

Technical Field

[0001] The present invention belongs to the technical field of switched reluctance motor control, and in particular relates to a switched reluctance motor five-level power converter for hybrid vehicles. 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 a top priority. With the rapid increase in the number of cars in my country, automobile emissions have also brought huge problems to the environment. Electric vehicles have received more and more attention because they only use electricity, a renewable secondary energy source, and do not emit gaseous pollutants.

[0003] The switched reluctance motor drive system is another drive solution for electric vehicles with great market potential. 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, and its output performance is also relatively good. It will run longer in harsh environments. It has good speed regulation performance, strong overload capacity, and a wider speed regulation range than permanent magnet synchronous motors. In terms of motor control, compared with other motor drivers, the switched reluctance motor has high controllability, the motor winding current and torque direction are related to each other, and the forward and reverse rotation only needs to set the conduction sequence of each phase of the motor. The topological structure of the switched reluctance motor power conversion circuit is simpler and the number of switches is less. Since the switched reluctance motor has many inherent advantages such as high efficiency, high reliability, high starting torque and high fault tolerance, it has excellent prospects as a hybrid electric vehicle propulsion system.

[0004] At present, the traditional drive system of the switched reluctance motor uses a traditional asymmetric half-bridge power converter, which is a three-level power converter. The topology diagram of the traditional asymmetric half-bridge power converter is as follows: Figure 7 .like Figure 8~Figure 10 , 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, and it is impossible to control the motor torque more deeply. Although the current five-level power converter meets the multi-level output, the number of switches and diodes used in most of them is relatively large and redundant. It cannot meet the simplest design principle. More switches and diodes will also increase the switching loss and affect the efficiency of the motor. For five-level control, more switches mean more complex control methods and it is more difficult to achieve better results. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a five-level switched reluctance motor power converter for hybrid vehicles, which solves the problem that the existing three-level converter cannot meet the requirements of voltage diversity, high fault tolerance, high precision and diversified selection of excitation and demagnetization of motor control, as well as the problem of redundant use of existing multi-level switching tubes and diodes.

[0006] 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 for hybrid vehicles, comprising an energy storage capacitor module, a bridge arm structure and a transverse branch structure of each phase in three phases;

[0007] The bridge arm structure of each phase in the three phases is the same, and both include a first bridge arm and a second bridge arm connected in parallel. The first bridge arm and the second bridge arm have the same structure, and both include a switch tube module and a diode module connected to each other, wherein one end of the energy storage capacitor module is respectively connected to one end of the bridge arm structure of each phase and one end of the power supply, and the other end of the energy storage capacitor module is connected to the other end of the bridge arm structure of each phase and the other end of the power supply;

[0008] The transverse branch structure of each phase in the three phases is the same, and both include a first transverse branch and a second transverse branch. The first transverse branch and the second transverse branch have the same structure, and both are provided with a transverse switch tube module and a transverse diode module.

[0009] In the first transverse branch of each phase, one end of the transverse switch tube module and one end of the transverse diode module are connected to the midpoint of the energy storage capacitor module, the other end of the transverse switch tube module is respectively connected to the switch tube module and the diode module of the first bridge arm, and the other end of the transverse diode module is connected to the midpoint of the diode module of the second bridge arm;

[0010] In the second transverse branch of each phase, one end of the transverse switch tube module and one end of the transverse diode module are connected to the midpoint of the energy storage capacitor module, the other end of the transverse switch tube module is respectively connected to the switch tube module and the diode module of the second bridge arm, and the other end of the transverse diode module is connected to the midpoint of the diode module of the first bridge arm.

[0011] Furthermore: the energy storage capacitor module includes a capacitor C1 and a capacitor C2 connected in series with the power supply, and the connection point of the capacitor C1 and the capacitor C2 serves as the midpoint of the energy storage capacitor module.

[0012] Further: the switch tube module of the first bridge arm is provided with a switch tube S1, and the diode module of the first bridge arm includes a diode D3 and a diode D4 connected to each other;

[0013] The collector of the switch tube S1 is connected to the positive electrode of the power supply, the emitter of the switch tube S1 is connected to the cathode of the diode D3, and the anode of the diode D3 is connected to the negative electrode of the power supply through the diode D4.

[0014] Further: the switch tube module of the second bridge arm is provided with a switch tube S4, and the diode module of the first bridge arm includes a diode D1 and a diode D2 connected to each other;

[0015] The emitter of the switch tube S4 is connected to the negative electrode of the power supply, the collector of the switch tube S4 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to the positive electrode of the power supply through the diode D1.

[0016] Further: the lateral switch tube module of the first lateral branch includes a switch tube S2 and a diode D5;

[0017] The collector of the switch tube S2 is connected to the midpoint of the energy storage capacitor module, and the emitter of the switch tube S2 is connected to the emitter of the switch tube S1 through the diode D5;

[0018] The transverse diode module of the first transverse branch is provided with a diode D6, an anode of the diode D6 is connected to the midpoint of the energy storage capacitor module, and a cathode of the diode D6 is connected to the midpoint of the diode module of the second bridge arm.

[0019] Further: the lateral switch tube module of the second lateral branch includes a switch tube S3 and a diode D8;

[0020] The emitter of the switch tube S3 is connected to the midpoint of the energy storage capacitor module, and the collector of the switch tube S3 is connected to the collector of the switch tube S4 through the diode D8;

[0021] The transverse diode module of the second transverse branch is provided with a diode D7, the cathode of the diode D7 is connected to the midpoint of the energy storage capacitor module, and the anode of the diode D7 is connected to the midpoint of the diode module of the first bridge arm.

[0022] The beneficial effects of the present invention are:

[0023] (1) The present invention provides a five-level power converter for a switched reluctance motor for hybrid vehicles. The intermediate level is realized by adding a transverse switch tube module and a transverse diode module to the traditional three-phase system, thereby achieving a multi-level output. Based on the connection relationship between the switch tube module, the diode module, the transverse switch tube module and the transverse diode module of each phase in the three-phase system, the five different output voltage states of the switched reluctance motor are realized by turning on and off the two switch tubes of each phase and the transverse switch tube, thereby improving the flexibility of the motor. At the same time, since the excitation and demagnetization are no longer at a single level, the speed of the winding excitation and demagnetization can be changed to a certain extent, facilitating more in-depth control.

[0024] (2) 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 to quickly demagnetize 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a schematic circuit diagram of a five-level power converter of a switched reluctance motor used in the field of hybrid vehicles.

[0026] Figure 2 The present invention is a fast excitation state circuit diagram of a five-level power converter of a switched reluctance motor used in the field of hybrid vehicles.

[0027] Figure 3 The present invention is a circuit diagram of the excitation state of a five-level power converter of a switched reluctance motor used in the field of hybrid vehicles.

[0028] Figure 4 The present invention is a freewheeling state circuit diagram of a five-level power converter of a switched reluctance motor used in the field of hybrid vehicles.

[0029] Figure 5 The present invention is a circuit diagram of a demagnetization state of a five-level power converter of a switched reluctance motor used in the field of hybrid vehicles.

[0030] Figure 6 The present invention is a circuit diagram of a five-level power converter of a switched reluctance motor for hybrid vehicles in a fast demagnetization state.

[0031] Figure 7 The schematic diagram of the circuit of a three-level power converter of a switched reluctance motor in the prior art.

[0032] Figure 8 The present invention is a circuit diagram of the excitation state of a three-level power converter of a switched reluctance motor in the prior art.

[0033] Fig. 9 The present invention is a circuit diagram of a zero-voltage freewheeling state of a three-level power converter of a switched reluctance motor in the prior art.

[0034] Fig.10The present invention is a circuit diagram of a demagnetization state of a three-level power converter of a switched reluctance motor in the prior art. DETAILED DESCRIPTION

[0035] 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.

[0036] like Figure 1 As shown, in one embodiment of the present invention, a five-level power converter of a switched reluctance motor for hybrid vehicles includes an energy storage capacitor module, a bridge arm structure and a transverse branch structure of each phase in three phases;

[0037] The bridge arm structure of each phase in the three phases is the same, and both include a first bridge arm and a second bridge arm connected in parallel. The first bridge arm and the second bridge arm have the same structure, and both include a switch tube module and a diode module connected to each other, wherein one end of the energy storage capacitor module is respectively connected to one end of the bridge arm structure of each phase and one end of the power supply, and the other end of the energy storage capacitor module is connected to the other end of the bridge arm structure of each phase and the other end of the power supply;

[0038] The transverse branch structure of each phase in the three phases is the same, and both include a first transverse branch and a second transverse branch. The first transverse branch and the second transverse branch have the same structure, and both are provided with a transverse switch tube module and a transverse diode module.

[0039] In the first transverse branch of each phase, one end of the transverse switch tube module and one end of the transverse diode module are connected to the midpoint of the energy storage capacitor module, the other end of the transverse switch tube module is respectively connected to the switch tube module and the diode module of the first bridge arm, and the other end of the transverse diode module is connected to the midpoint of the diode module of the second bridge arm;

[0040] In the second transverse branch of each phase, one end of the transverse switch tube module and one end of the transverse diode module are connected to the midpoint of the energy storage capacitor module, the other end of the transverse switch tube module is respectively connected to the switch tube module and the diode module of the second bridge arm, and the other end of the transverse diode module is connected to the midpoint of the diode module of the first bridge arm.

[0041] In this embodiment, the present invention realizes the emergence of an intermediate level by adding a lateral switch tube module and a lateral diode module to the traditional three-phase case, thereby achieving multi-level output. Five different states of the output voltage of the switched reluctance motor are realized through the two switch tubes of each phase and the conduction and shutdown of the lateral switch tube, thereby improving the flexibility of the motor. At the same time, since the excitation and demagnetization are no longer at a single level, the speed of the winding excitation and demagnetization can be changed to a certain extent, thereby facilitating more in-depth control.

[0042] The energy storage capacitor module includes a capacitor C1 and a capacitor C2 which are connected in series with a power source, and a connection point between the capacitor C1 and the capacitor C2 serves as a midpoint of the energy storage capacitor module.

[0043] The switch tube module of the first bridge arm is provided with a switch tube S1, and the diode module of the first bridge arm includes a diode D3 and a diode D4 connected to each other;

[0044] The collector of the switch tube S1 is connected to the positive electrode of the power supply, the emitter of the switch tube S1 is connected to the cathode of the diode D3, and the anode of the diode D3 is connected to the negative electrode of the power supply through the diode D4.

[0045] The switch tube module of the second bridge arm is provided with a switch tube S4, and the diode module of the first bridge arm includes a diode D1 and a diode D2 connected to each other;

[0046] The emitter of the switch tube S4 is connected to the negative electrode of the power supply, the collector of the switch tube S4 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to the positive electrode of the power supply through the diode D1.

[0047] In this embodiment, the two bridge arms of each phase are composed of a switch tube and two diodes, but the connection sequence is different because of the upper and lower bridge arms.

[0048] The lateral switch tube module of the first lateral branch includes a switch tube S2 and a diode D5;

[0049] The collector of the switch tube S2 is connected to the midpoint of the energy storage capacitor module, and the emitter of the switch tube S2 is connected to the emitter of the switch tube S1 through the diode D5;

[0050] The transverse diode module of the first transverse branch is provided with a diode D6, an anode of the diode D6 is connected to the midpoint of the energy storage capacitor module, and a cathode of the diode D6 is connected to the midpoint of the diode module of the second bridge arm.

[0051] The lateral switch tube module of the second lateral branch includes a switch tube S3 and a diode D8;

[0052] The emitter of the switch tube S3 is connected to the midpoint of the energy storage capacitor module, and the collector of the switch tube S3 is connected to the collector of the switch tube S4 through the diode D8;

[0053] The transverse diode module of the second transverse branch is provided with a diode D7, the cathode of the diode D7 is connected to the midpoint of the energy storage capacitor module, and the anode of the diode D7 is connected to the midpoint of the diode module of the first bridge arm.

[0054] In this embodiment, Figure 1 to Figure 6 It is only for one phase, and the structures corresponding to the three phases A, B, and C are the same. Therefore, the present invention analyzes one phase to replicate the output state of the three phases.

[0055] like Figure 2 As shown in the figure, when the switches S1 and S4 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 S1 to the switched reluctance motor, and then flows from the switch S4 to the negative pole of the power supply. At this time, high voltage (UC1+UC2) is applied to the winding for excitation to achieve rapid excitation, and the switch state is "+2".

[0056] like Figure 3 As shown in the figure, when the switches S2 and S4 are both turned on and the diode D5 is turned on, the current flows from the midpoint of the capacitors C1 and C2 through the switch S2, through the diode D5, through the switched reluctance motor, and then from the switch S4 to the negative pole of the power supply. At this time, the excitation is achieved by applying a low voltage UC2 to the winding, and the switch state is "+1".

[0057] like Figure 4 As shown, when the switch tube S3 is turned on, the diode D5 is turned on, and the current direction is from the diodes D3 and D4 to the switch tube S4 after passing through the switched reluctance motor. At this time, it is a zero-voltage freewheeling state, and the switch state is "0".

[0058] like Figure 5 As shown in the figure, when the switch tube S3 is turned on, and the diodes D3, D4, and D8 are all turned on, the current flows from the negative pole of the power supply through the diode D4, through the diode D3, through the switched reluctance motor, and then from the diode D8 through the switch tube S3 to the midpoint of the capacitors C1 and C2, feeding the electric energy back to the capacitor C2. At this time, it is in the demagnetization state, and the switch state is "-1".

[0059] like Figure 6 As shown in the figure, when the switch tubes are all turned off, the current flows from diodes D4 and D3 to the switched reluctance motor and then feeds back electrical energy from diodes D2 and D1 to capacitors C1 and C2. At this time, it is a fast demagnetization state, and the switch state is "-2".

[0060] 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.

[0061] The beneficial effects of the present invention are as follows: the present invention provides a five-level power converter for a switched reluctance motor for hybrid vehicles, which realizes the appearance of an intermediate level by adding a transverse switch tube module and a transverse diode module in the case of a traditional three-phase, thereby achieving a multi-level output. Based on the connection relationship between the switch tube module, the diode module, the transverse switch tube module and the transverse diode module of each phase in the three-phase, the five different states of the output voltage of the switched reluctance motor are realized by turning on and off the two switch tubes of each phase and the transverse switch tube, thereby improving the flexibility of the motor. At the same time, since the excitation and demagnetization are no longer at a single level, the speed of the winding excitation and demagnetization can be changed to a certain extent, which facilitates more in-depth control.

[0062] The multi-level levels of the proposed power converter 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 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 to quickly demagnetize 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, which reduces switching losses and improves device utilization. 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.

[0063] 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 for a switched reluctance motor used in the field of hybrid vehicles, characterized in that: It includes energy storage capacitor module, bridge arm structure and lateral branch structure of each phase in three phases; The bridge arm structure of each phase in the three phases is the same, and both include a first bridge arm and a second bridge arm connected in parallel. The first bridge arm and the second bridge arm have the same structure, and both include a switch tube module and a diode module connected to each other, wherein one end of the energy storage capacitor module is respectively connected to one end of the bridge arm structure of each phase and one end of the power supply, and the other end of the energy storage capacitor module is connected to the other end of the bridge arm structure of each phase and the other end of the power supply; The transverse branch structure of each phase in the three phases is the same, and both include a first transverse branch and a second transverse branch. The first transverse branch and the second transverse branch have the same structure, and both are provided with a transverse switch tube module and a transverse diode module. In the first transverse branch of each phase, one end of the transverse switch tube module and one end of the transverse diode module are connected to the midpoint of the energy storage capacitor module, the other end of the transverse switch tube module is respectively connected to the switch tube module and the diode module of the first bridge arm, and the other end of the transverse diode module is connected to the midpoint of the diode module of the second bridge arm; In the second transverse branch of each phase, one end of the transverse switch tube module and one end of the transverse diode module are connected to the midpoint of the energy storage capacitor module, the other end of the transverse switch tube module is respectively connected to the switch tube module and the diode module of the second bridge arm, and the other end of the transverse diode module is connected to the midpoint of the diode module of the first bridge arm; The switch tube module of the first bridge arm is provided with a switch tube S1, and the diode module of the first bridge arm includes a diode D3 and a diode D4 connected to each other; The collector of the switch tube S1 is connected to the positive electrode of the power supply, the emitter of the switch tube S1 is connected to the cathode of the diode D3, and the anode of the diode D3 is connected to the negative electrode of the power supply through the diode D4; The lateral switch tube module of the first lateral branch includes a switch tube S2 and a diode D5; The collector of the switch tube S2 is connected to the midpoint of the energy storage capacitor module, and the emitter of the switch tube S2 is connected to the emitter of the switch tube S1 through the diode D5; The transverse diode module of the first transverse branch is provided with a diode D6, an anode of the diode D6 is connected to the midpoint of the energy storage capacitor module, and a cathode of the diode D6 is connected to the midpoint of the diode module of the second bridge arm.

2. The switched reluctance motor five-level power converter for hybrid vehicles according to claim 1, characterized in that: The energy storage capacitor module includes a capacitor C1 and a capacitor C2 which are connected in series with a power source, and a connection point between the capacitor C1 and the capacitor C2 serves as a midpoint of the energy storage capacitor module.

3. The switched reluctance motor five-level power converter for hybrid vehicles according to claim 1, characterized in that: The switch tube module of the second bridge arm is provided with a switch tube S4, and the diode module of the first bridge arm includes a diode D1 and a diode D2 connected to each other; The emitter of the switch tube S4 is connected to the negative electrode of the power supply, the collector of the switch tube S4 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to the positive electrode of the power supply through the diode D1.

4. The switched reluctance motor five-level power converter for hybrid vehicles according to claim 3, characterized in that: The lateral switch tube module of the second lateral branch includes a switch tube S3 and a diode D8; The emitter of the switch tube S3 is connected to the midpoint of the energy storage capacitor module, and the collector of the switch tube S3 is connected to the collector of the switch tube S4 through the diode D8; The transverse diode module of the second transverse branch is provided with a diode D7, the cathode of the diode D7 is connected to the midpoint of the energy storage capacitor module, and the anode of the diode D7 is connected to the midpoint of the diode module of the first bridge arm.

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