Topological structure of power conversion unit of four-phase switched reluctance motor and control method

Abstract

The invention discloses a four-phase switched reluctance motor power conversion unit topological structure and a control method, and belongs to the field of switched reluctance motor control. Comprising two groups of bridge arm units, a plurality of bridge arms are arranged in the bridge arm units, each bridge arm in the bridge arm units is connected between a power supply positive electrode and a power supply negative electrode, windings of the switch magnetic self-motor are connected in the bridge arm units, and the windings of two adjacent phases are connected in different bridge arm units; each group of bridge arm units is provided with three bridge arms, namely two controllable bridge arms and one common bridge arm, and the winding is connected between the controllable bridge arms and the common bridge arm to form a conduction loop and a follow current loop of the winding. According to the four-phase switched reluctance motor power conversion unit topological structure and the control method, two adjacent phases of windings are arranged in different bridge arm units, two controllable bridge arms and one common bridge arm are utilized in each group of bridge arm units to realize a conduction loop and a follow current loop of the winding in each group of bridge arm units, and the number of power devices is reduced.

Description

Technical Field

[0001] A topology structure and control method for a power conversion unit of a four-phase switched reluctance motor belong to the field of switched reluctance motor control. Background Art

[0002] As a new type of high-efficiency speed-regulated motor, the switched reluctance motor has the advantages of simple structure, high reliability, flexible controllability, good speed regulation performance, etc. However, the motor body does not have self-starting performance and needs to be matched with a control system (or controller) to achieve starting and speed regulation functions.

[0003] As the core functional unit of the switched reluctance motor control system, the topology structure of its power conversion unit is unique and more complex than that of a general frequency converter. Two switching tubes need to be connected in series for each phase winding to control the phase winding current, and two diodes are also required to cooperate to achieve the freewheeling function when the phase winding current is turned off. For example, the technical solution recorded in the Chinese invention patent with the application number 201710969790.8, the application date of October 18, 2017, and the patent name of "A Switched Reluctance Motor System Based on Split Current Sampling of Dual Busbars".

[0004] The unique circuit topology structure of the switched reluctance motor determines that the number of switching devices required for the power conversion unit is more than that of the frequency converter, resulting in problems such as large volume and high cost of the switched reluctance motor controller. Especially in the switched reluctance motor control system with four or more phases, the above problems are more obvious. Therefore, designing a technical solution to reduce the number of power devices to avoid problems such as large volume and high cost of the switched reluctance motor controller has become an urgent problem to be solved in this field. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: to overcome the deficiencies of the prior art and provide a topology structure and control method for a power conversion unit of a four-phase switched reluctance motor, which arranges the windings of adjacent two phases in different bridge arm units, and uses two controllable bridge arms and one common bridge arm in each group of bridge arm units to realize the conduction loop and freewheeling loop of the inner winding, thereby reducing the number of power devices.

[0006] The technical solution adopted by the present invention to solve its technical problems is: the topology structure of the power conversion unit of the four-phase switched reluctance motor includes bridge arm units, and multiple bridge arms are arranged in the bridge arm units. Each bridge arm in the bridge arm unit is connected between the positive power supply and the negative power supply, and the windings of the switched reluctance motor are connected in the bridge arm units. Its characteristics are: the bridge arm units include two groups, and the windings of adjacent two phases are connected in different bridge arm units; three bridge arms are arranged in each group of bridge arm units: two controllable bridge arms and one common bridge arm, and the windings are connected between the controllable bridge arms and the common bridge arm to form a conduction loop and a freewheeling loop of the windings.

[0007] Preferably, the two controllable bridge arms include a first switching tube and a first freewheeling diode connected in series with the switching tube; the common bridge arm includes two second switching tubes connected in series and a second freewheeling diode connected in parallel with each second switching tube. The two second switching tubes in the common bridge arm respectively form a conduction loop of the winding with the first switching tubes in the two controllable bridge arms, and the two second freewheeling diodes in the common bridge arm respectively form a freewheeling loop of the winding with the first freewheeling diodes in the two controllable bridge arms.

[0008] Preferably, the conduction directions of the second switching tube and the second freewheeling diode in the common bridge arm are opposite, and the conduction directions of the first switching tube and the first freewheeling diode in each controllable bridge arm are opposite.

[0009] Preferably, the two first switching tubes in the two controllable bridge arms are arranged staggeredly.

[0010] Preferably, in each group of bridge arm units, one ends of the two windings are respectively connected between the two second switching tubes of the common bridge arm, and the other ends of the two windings are respectively connected between the first switching tube and the first freewheeling diode of the two controllable bridge arms.

[0011] Preferably, a capacitor is also connected between the positive power supply terminal and the negative power supply terminal.

[0012] A control method implemented by a topology structure of a power conversion unit of a four-phase switched reluctance motor, characterized by comprising the following steps: The controller sequentially controls the winding of each phase of the switched reluctance motor to conduct and turn off cyclically. When the winding conducts: the controller controls the controllable bridge arm and the common bridge arm in the corresponding bridge arm unit of the current-phase winding to conduct, forming a conduction loop between the corresponding winding and the power supply. When the winding turns off: the controller controls the controllable bridge arm and the common bridge arm in the corresponding bridge arm unit of the current winding to turn off, and the turned-off winding realizes freewheeling through the freewheeling loop formed by the controllable bridge arm and the common bridge arm in its corresponding bridge arm unit; the controller controls the controllable bridge arm and the common bridge arm in the corresponding bridge arm unit of the adjacent next-phase winding to conduct and form a conduction loop between the corresponding winding and the power supply.

[0013] Compared with the prior art, the beneficial effects of the present invention are: In the topology structure and control method of the four-phase switched reluctance motor power conversion unit, the windings of adjacent phases are arranged in different bridge arm units. In each group of bridge arm units, two controllable bridge arms and a common bridge arm are used to realize the conduction circuit and freewheeling circuit of the inner winding. The symmetric drive characteristics of the four-phase motor are fully utilized, and mutually exclusive conduction phases share a power device. While reducing the number of power devices, the same control effect as that of the four-phase independent asymmetric half-bridge circuit is achieved, avoiding the problems of large volume and high cost of the switched reluctance motor controller in the prior art, thereby reducing the volume of the control system and improving the power density of the control system. Description of the Drawings

[0014] Figure 1 It is a schematic diagram of the topology structure of the four-phase switched reluctance motor power conversion unit.

[0015] Figure 2 It is the topology structure of the four-phase switched reluctance motor power conversion unit A Schematic diagram of phase conduction state.

[0016] Figure 3 It is the topology structure of the four-phase switched reluctance motor power conversion unit A Schematic diagram of phase freewheeling state.

[0017] Figure 4 It is the topology structure of the four-phase switched reluctance motor power conversion unit B Schematic diagram of phase conduction state.

[0018] Figure 5 It is the topology structure of the four-phase switched reluctance motor power conversion unit B Schematic diagram of phase freewheeling state.

[0019] Figure 6 It is the topology structure of the four-phase switched reluctance motor power conversion unit C Schematic diagram of phase conduction state.

[0020] Figure 7 It is the topology structure of the four-phase switched reluctance motor power conversion unit C Schematic diagram of phase freewheeling state.

[0021] Figure 8 It is the topology structure of the four-phase switched reluctance motor power conversion unit D Schematic diagram of phase conduction state.

[0022] Figure 9 It is the topology structure of the four-phase switched reluctance motor power conversion unit D Schematic diagram of phase freewheeling state. Detailed Implementation Manner

[0023] Figures 1 - 9This is the best embodiment of the present invention. The present invention will be further described below in conjunction with the attached drawings. Figures 1 - 9 Further description of the present invention will be made.

[0024] A topology structure of a power conversion unit for a four-phase switched reluctance motor includes two bridge arm units connected in parallel between the positive and negative poles of a power supply. The structures of the two bridge arm units are the same. Each bridge arm unit includes three independent bridge arms, and a total of four bridge arms in the two bridge arm units are connected in parallel between the positive and negative poles of the power supply at the same time. The three bridge arms in each bridge arm unit include two controllable bridge arms and a common bridge arm located between the two controllable bridge arms. Switching tubes are provided in the two controllable bridge arms, and the switching tubes in the two controllable bridge arms are arranged staggeredly.

[0025] The four-phase windings of the switched reluctance motor: A Phase winding, B Phase winding, C Phase winding, and D Phase winding are connected to the two bridge arm units. Specifically: A Phase winding and C Phase winding are respectively connected to the same bridge arm unit. A Phase winding and C One ends of the phase winding are respectively connected to the two controllable bridge arms. A Phase winding and C The other ends of the phase winding are simultaneously connected to the common bridge arm. B Phase winding and D Phase winding are respectively connected to the same bridge arm unit. B Phase winding and D One ends of the phase winding are respectively connected to the two controllable bridge arms. B Phase winding and D The other ends of the phase winding are simultaneously connected to the common bridge arm.

[0026] A capacitor C 1 is also connected between the positive and negative poles of the power supply. As Figure 1 shown, the positive pole of the power supply is simultaneously connected to one end of the capacitor C 1, the collectors of the switching tubes T 1~ T 2, the cathodes of the diodes D 1~ D 2, and the collectors of the switching tubes T 1’~ T 2’. The negative pole of the power supply is simultaneously connected to the other end of the capacitor D 1, the emitters of the switching tubes D 2’, the cathodes of the diodes C 1’~ T 3~ T 4, the cathodes of the diodes D 3~ DThe anode of 4, and the switching transistor T 3’~ T The emitter of 4’, the diode D 3’~ D The anode of 4’.

[0027] The switching transistor T The emitter of 1 is connected to the diode D The cathode of 3 and A The phase winding L A One end of. A The phase winding L A The other end of is connected to the switching transistor T The emitter of 2, the switching transistor T The collector diode of 3 D The anode of 1 and the diode D The cathode of 4, and is connected to C The phase winding L C One end of. C The phase winding L C The other end of is connected to the diode D The anode of 2 and the switching transistor T The collector of 2.

[0028] The above-mentioned switching transistor T 1~ T 4, the diode D 1~ D 4 form the first group of bridge arm units, where the series-connected switching transistors T 1 and the diode D 3 form the first controllable bridge arm, and the series-connected diodes D 2 and the switching transistor T 4 form the second controllable bridge arm, and the series-connected switching transistors T 2~ T 3, the diode T 1 parallel to the switching transistor D And the diode T 3 parallel to the switching transistor D 4 form the common bridge arm.

[0029] The switching transistor T The emitter of 1’ is connected to the diode D The cathode of 3’ and B The phase winding L B One end of. B The phase winding L B The other end of is connected to the switching transistor TThe emitter of 2’ and the switching transistor T The collector diode of 3’ D The anode of 1’ and the diode D The cathode of 4’ and connect simultaneously D Phase winding L D One end of D Phase winding L D The other end of connect to the diode D The anode of 2’ and the switching transistor T The collector of 2’

[0030] The above-mentioned switching transistor T 1’~ T 4’, the diode D 1’~ D 4’ form the second group of bridge arm units, where the series-connected switching transistors T 1’ and the diode D 3’ form the first controllable bridge arm, and the series-connected diodes D 2’ and the switching transistor T 4’ form the second controllable bridge arm, and the series-connected switching transistors T 2’~ T 3’, the diode in parallel with the switching transistor T 1’ parallel to the switching transistor D 1’ and the diode in parallel with the switching transistor T 3’ parallel to the diode D 4’ form the common bridge arm

[0031] The above-mentioned switching transistor T 1~ T 4 and the switching transistor T 1’~ T 4’ can be realized by controllable devices well-known in the art, such as IGB T

[0032] The specific working process and working principle are as follows: The phase conduction sequence of the four-phase switched reluctance motor follows A Phase → B Phase → C Phase → D Phase → A Phase in a cyclic conduction manner. Specifically: A Phase conduction: The controller controls the switching transistor T 1 and the switching transistor T 3 to conduct, and the power supply is from the positive power supply terminal through the switching transistor T 1, A Phase winding L A ​and the switching transistors T 3 returns to the negative power supply terminal, as Figure 2 shown. When A the phase winding L A is turned off, A the current in the phase winding L A flows through diode D 1 and diode D 3 to achieve freewheeling, as Figure 3 shown.

[0033] B Phase conduction: The controller controls switching transistors T 1' and switching transistor T 3' to conduct. The power supply goes from the positive power supply terminal through switching transistor T 1', B the phase winding L B and switching transistor T 3' back to the negative power supply terminal, as Figure 4 shown. When B the phase winding L B is turned off, B the current in the phase winding L B flows through diode D 1' and diode D 3' to achieve freewheeling, as Figure 5 shown.

[0034] C Phase conduction: The controller controls switching transistors T 2 and switching transistor T 4 to conduct. The power supply goes from the positive power supply terminal through switching transistor T 2, C the phase winding L C and switching transistor T 4 back to the negative power supply terminal, as Figure 6 shown. When C the phase winding L C is turned off, C the current in the phase winding L C flows through diode D 2 and diode D 4 to achieve freewheeling, as Figure 7 shown.

[0035] D Phase conduction: The controller controls the switching transistorsT 2' and the switching transistor T 4' is turned on, and the power supply is supplied from the positive power supply terminal, through the switching transistor T 2', D the phase winding L D and the switching transistor T 4' and returns to the negative power supply terminal, as Figure 8 shown. When D the phase winding L D is turned off, D the current in the phase winding L D flows through the diode D 2' and the diode D 4' to realize freewheeling, as Figure 9 shown.

[0036] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention in any other form. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A four-phase switched reluctance motor power conversion unit topology structure, comprising a bridge arm unit, wherein the bridge arm unit is provided with a plurality of bridge arms, each bridge arm in the bridge arm unit is connected between a positive pole of a power supply and a negative pole of a power supply, and a winding of the switched reluctance motor is connected to the bridge arm unit, characterized in that: The bridge arm unit includes two groups, and the windings of two adjacent phases are connected in different bridge arm units; each group of bridge arm units is provided with three bridge arms: two controllable bridge arms and one common bridge arm, and the windings are connected between the controllable bridge arms and the common bridge arm to form a conduction circuit and a freewheeling circuit of the winding.

2. The four-phase switched reluctance motor power conversion unit topology structure according to claim 1 is characterized in that: The two controllable bridge arms include a first switch tube and a first freewheeling diode connected in series with the switch tube; the common bridge arm includes two second switch tubes connected in series and a second freewheeling diode connected in parallel with each second switch tube, the two second switch tubes in the common bridge arm respectively form a conduction circuit of the winding with the first switch tubes in the two controllable bridge arms, and the two second freewheeling diodes in the common bridge arm respectively form a freewheeling circuit of the winding with the first freewheeling diodes in the two controllable bridge arms.

3. The four-phase switched reluctance motor power conversion unit topology structure according to claim 2 is characterized in that: The conduction direction of the second switch tube in the common bridge arm is opposite to that of the second freewheeling diode, and the conduction direction of the first switch tube in each controllable bridge arm is opposite to that of the first freewheeling diode.

4. The four-phase switched reluctance motor power conversion unit topology structure according to claim 2 is characterized in that: The two first switch tubes in the two controllable bridge arms are arranged alternately.

5. The four-phase switched reluctance motor power conversion unit topology structure according to claim 2 is characterized in that: In each group of bridge arm units, one end of the two windings is respectively connected between the two second switch tubes of the common bridge arm, and the other ends of the two windings are respectively connected between the first switch tubes and the first freewheeling diode of the two controllable bridge arms.

6. The four-phase switched reluctance motor power conversion unit topology structure according to claim 2 is characterized in that: A capacitor is also connected between the positive pole of the power supply and the negative pole of the power supply.

7. A control method implemented by the topological structure of the power conversion unit of the four-phase switched reluctance motor according to any one of claims 1 to 4, characterized in that: The steps include: The controller controls the switching motor's windings to cycle on and off in sequence. When the winding is turned on: the controller controls the controllable bridge arm and the common bridge arm in the bridge arm unit corresponding to the current phase winding to be turned on, forming a conduction loop between the corresponding winding and the power supply; When the winding is turned off: the controller controls the controllable bridge arm and the common bridge arm in the corresponding bridge arm unit of the current winding to be turned off, and the turned-off winding realizes freewheeling through the freewheeling circuit formed by the controllable bridge arm and the common bridge arm in its corresponding bridge arm unit; the controller controls the controllable bridge arm and the common bridge arm in the corresponding bridge arm unit of the adjacent next phase winding to be turned on and form a conduction circuit between the corresponding winding and the power supply.

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