A short-tail topology circuit and control strategy for driving switched reluctance motors

Abstract

This invention relates to the field of switched reluctance motor drive control technology, specifically a short-tail topology circuit and control strategy suitable for driving switched reluctance motors. This invention solves the problems of large torque ripple and significant axial and radial noise caused by existing switched reluctance motor drive control circuits. A short-tail topology circuit suitable for driving switched reluctance motors includes a switched reluctance motor, an additional bridge arm, and an N-phase inverter bridge arm; wherein the windings of the switched reluctance motor are star-connected N-phase windings; the additional bridge arm is composed of a freewheeling diode and a power switch connected in series; the midpoint of the additional bridge arm is connected to the neutral point of the N-phase winding; the midpoint of the N-phase inverter bridge arm is connected one-to-one with the leads of the N-phase winding; the N-phase inverter bridge arms together constitute an N-phase inverter. This invention is applicable to electric vehicles, agricultural machinery, heavy machinery, mining machinery, flight equipment, home appliances, military facilities, and other fields.

Description

Technical Field

[0001] This invention relates to the field of switched reluctance motor drive control technology, specifically a short-tail topology circuit and control strategy suitable for driving switched reluctance motors. Background Technology

[0002] Switched reluctance motors (SRMs), as typical rare-earth-free motors, avoid the use of rare-earth permanent magnet materials in their manufacturing, reducing manufacturing costs and eliminating the risk of permanent magnet demagnetization under extreme operating conditions. Compared with induction motors and synchronous reluctance motors, which are also rare-earth-free motors, SRMs have a simpler rotor structure, higher strength, and lower cost, making them more suitable for extreme conditions such as high temperature and high pressure, vacuum and low temperature, and high-frequency vibration. Therefore, theoretical analysis shows that SRMs are ideal drive systems for applications such as electric vehicles, agricultural machinery, heavy machinery, mining machinery, aerospace equipment, home appliances, and military facilities, and can increase the lifespan of existing drive systems by 2 times or more.

[0003] Currently, switched reluctance motor drive control circuits mainly include two types: one is the traditional asymmetrical half-bridge power converter circuit, and the other is the modular converter circuit. The traditional asymmetrical half-bridge power converter circuit connects an asymmetrical half-bridge circuit (such as...) across the two ends of each phase winding. Figure 1 As shown), an asymmetrical half-bridge circuit is used to unipolarly excite each phase winding, generating a unidirectional pulse winding current (such as...). Figure 2 (As shown). The modular converter circuit connects an additional bridge arm consisting of two power switches to the neutral point of the three-phase windings. This additional bridge arm, together with the inverter bridge arm connected to the other end of each phase winding, forms an H-bridge circuit (e.g., ...). Figure 3 As shown), the H-bridge circuit is used to bipolarly excite each phase winding, generating a bidirectional pulse winding current (such as...). Figure 4 (As shown).

[0004] However, in practical applications, both traditional asymmetrical half-bridge power converter circuits and modular converter circuits suffer from the following problems: First, both unidirectional and bidirectional pulse winding currents experience severe fluctuations during commutation, resulting in significant torque pulsation in the motor. Second, neither traditional asymmetrical half-bridge power converter circuits nor modular converter circuits incorporate axial and radial torque components into their control strategies, leading to substantial axial and radial noise in the motor. Therefore, it is necessary to invent a short-tail topology circuit and control strategy suitable for driving switched reluctance motors to solve the problems of significant torque pulsation and excessive axial and radial noise caused by existing switched reluctance motor drive control circuits. Summary of the Invention

[0005] To address the problems of large torque pulsation and significant axial and radial noise caused by existing switched reluctance motor drive control circuits, this invention provides a short-tail topology circuit and control strategy suitable for driving switched reluctance motors.

[0006] This invention is achieved using the following technical solution:

[0007] A short-tail topology circuit suitable for driving a switched reluctance motor includes a switched reluctance motor, an additional bridge arm, and an N-phase inverter bridge arm; N is a positive integer and N≥2;

[0008] Among them, the windings of the switched reluctance motor adopt N-phase windings with star connection;

[0009] The additional bridge arm consists of a freewheeling diode and a power switch connected in series.

[0010] The positive input terminal of the additional bridge arm is connected to the positive power supply terminal; the negative input terminal of the additional bridge arm is connected to the negative power supply terminal; the midpoint of the additional bridge arm is connected to the neutral point of the N-phase winding.

[0011] The positive input terminals of the N-phase inverter bridge arms are all connected to the positive power supply terminals; the negative input terminals of the N-phase inverter bridge arms are all connected to the negative power supply terminals; the midpoints of the N-phase inverter bridge arms are connected one-to-one with the leads of the N-phase windings; the N-phase inverter bridge arms together constitute the N-phase inverter.

[0012] Preferably, the cathode of the freewheeling diode of the additional bridge arm serves as the positive input terminal of the additional bridge arm, the anode of the freewheeling diode of the additional bridge arm is connected to the drain of the power switch of the additional bridge arm, and the source of the power switch of the additional bridge arm serves as the negative input terminal of the additional bridge arm.

[0013] When N=3, the control strategy based on this circuit includes:

[0014] I. Three-phase conduction mode:

[0015] The power switches and three-phase windings of the additional bridge arm are controlled to conduct, enabling the switched reluctance motor to enter the three-phase conduction mode. In this mode, the three-phase inverter is controlled using a general method, so that the upper power switches of the three-phase inverter bridge arms conduct alternately, and when the upper power switch of one phase inverter bridge arm is conducted, the lower power switches of the other two phase inverter bridge arms are conducted; or the lower power switches of the three-phase inverter bridge arms conduct alternately, and when the lower power switch of one phase inverter bridge arm is conducted, the upper power switches of the other two phase inverter bridge arms are conducted.

[0016] Taking the simultaneous conduction of the upper power switch of phase A inverter arm, the lower power switch of phase B inverter arm, and the lower power switch of phase C inverter arm as an example, the excitation path and freewheeling path are as follows:

[0017] Excitation path: The excitation current starts from the positive power supply terminal, flows sequentially through the upper power switch of the A-phase inverter bridge arm and the A-phase winding to the neutral point of the three-phase winding, then flows through the power switch of the auxiliary bridge arm and returns to the negative power supply terminal, then flows sequentially through the B-phase winding and the lower power switch of the B-phase inverter bridge arm and returns to the negative power supply terminal, and finally flows sequentially through the C-phase winding and the lower power switch of the C-phase inverter bridge arm and returns to the negative power supply terminal.

[0018] Freewheeling path: The freewheeling current starts from the negative power supply terminal, flows sequentially through the parasitic diode of the lower power switch of the A-phase inverter bridge arm, and the A-phase winding to reach the neutral point of the three-phase winding. Then, it flows back to the positive power supply terminal after passing through the freewheeling diode of the additional bridge arm. On the other hand, it flows sequentially through the B-phase winding and the parasitic diode of the upper power switch of the B-phase inverter bridge arm to return to the positive power supply terminal. On the third hand, it flows sequentially through the C-phase winding and the parasitic diode of the upper power switch of the C-phase inverter bridge arm to return to the positive power supply terminal.

[0019] II. Two-phase conduction mode:

[0020] The power switch of the additional bridge arm and two phase windings are turned on, so that the switched reluctance motor enters the two-phase conduction mode. In this mode, the three-phase inverter is controlled by a general method so that the upper power switches of the three-phase inverter bridge arms are turned on alternately, and when the upper power switch of one phase inverter bridge arm is turned on, the lower power switch of the other phase inverter bridge arm is turned on.

[0021] Taking the simultaneous conduction of the upper power switch of phase A inverter bridge arm and the lower power switch of phase B inverter bridge arm as an example, the excitation path, freewheeling path, and two demagnetization paths are as follows:

[0022] Excitation path: The excitation current starts from the positive power supply terminal, flows sequentially through the upper power switch of the A-phase inverter bridge arm and the A-phase winding to the neutral point of the three-phase winding, and then flows back to the negative power supply terminal after passing through the power switch of the auxiliary bridge arm. On the other hand, it flows sequentially through the B-phase winding and the lower power switch of the B-phase inverter bridge arm to return to the negative power supply terminal.

[0023] Freewheeling path: The freewheeling current starts from the negative power supply terminal, flows sequentially through the parasitic diode of the lower power switch of the A-phase inverter bridge arm, the A-phase winding, and reaches the neutral point of the three-phase winding. Then, it flows through the freewheeling diode of the additional bridge arm and returns to the positive power supply terminal. On the other hand, it flows sequentially through the B-phase winding and the parasitic diode of the upper power switch of the B-phase inverter bridge arm and returns to the positive power supply terminal.

[0024] The first demagnetizing path: The demagnetizing current starts from the negative power supply end, flows sequentially through the parasitic diode of the lower power switch of the A-phase inverter bridge arm, the A-phase winding, and reaches the neutral point of the three-phase winding. Then, it flows through the power switch of the additional bridge arm and returns to the negative power supply end, and flows sequentially through the B-phase winding and the lower power switch of the B-phase inverter bridge arm and returns to the negative power supply end.

[0025] The second demagnetizing path: The demagnetizing current starts from the positive power supply terminal, flows sequentially through the upper power switch of the A-phase inverter bridge arm and the A-phase winding, and reaches the neutral point of the three-phase winding. Then, it flows through the freewheeling diode of the additional bridge arm and returns to the positive power supply terminal. On the other hand, it flows sequentially through the B-phase winding and the parasitic diode of the upper power switch of the B-phase inverter bridge arm and returns to the positive power supply terminal.

[0026] III. Single-phase conduction mode:

[0027] The power switch of the additional bridge arm and one phase winding are turned on to enable the switched reluctance motor to enter single-phase conduction mode. In this mode, the three-phase inverter is controlled by a general method to make the upper power switches of the three-phase inverter bridge arm turn on alternately.

[0028] Taking the conduction of the upper power switch of the A-phase inverter bridge arm as an example, the excitation path and freewheeling path are as follows:

[0029] Excitation path: The excitation current starts from the positive power supply terminal, flows sequentially through the upper power switch of the A-phase inverter bridge arm and the A-phase winding to the neutral point of the three-phase winding, and then flows through the power switch of the additional bridge arm and returns to the negative power supply terminal.

[0030] Freewheeling path: The freewheeling current starts from the negative power supply terminal, flows sequentially through the parasitic diode of the lower power switch of the A-phase inverter bridge arm, the A-phase winding, and reaches the neutral point of the three-phase winding. Then it flows through the freewheeling diode of the additional bridge arm and returns to the positive power supply terminal.

[0031] Preferably, the drain of the power switch of the additional bridge arm is used as the positive input terminal of the additional bridge arm, the source of the power switch of the additional bridge arm is connected to the cathode of the freewheeling diode of the additional bridge arm, and the anode of the freewheeling diode of the additional bridge arm is used as the negative input terminal of the additional bridge arm.

[0032] When N=3, the control strategy based on this circuit includes:

[0033] I. Three-phase conduction mode:

[0034] The power switches and three-phase windings of the additional bridge arm are controlled to conduct, enabling the switched reluctance motor to enter the three-phase conduction mode. In this mode, the three-phase inverter is controlled using a general method, so that the upper power switches of the three-phase inverter bridge arms conduct alternately, and when the upper power switch of one phase inverter bridge arm is conducted, the lower power switches of the other two phase inverter bridge arms are conducted; or the lower power switches of the three-phase inverter bridge arms conduct alternately, and when the lower power switch of one phase inverter bridge arm is conducted, the upper power switches of the other two phase inverter bridge arms are conducted.

[0035] Taking the simultaneous conduction of the upper power switch of phase A inverter arm, the lower power switch of phase B inverter arm, and the lower power switch of phase C inverter arm as an example, the excitation path and freewheeling path are as follows:

[0036] Excitation path: The excitation current starts from the positive power supply terminal, flows sequentially through the upper power switch of the A-phase inverter bridge arm and the A-phase winding to the neutral point of the three-phase winding, and then flows sequentially through the power switch of the auxiliary bridge arm to the neutral point of the three-phase winding. Then, it flows sequentially through the B-phase winding and the lower power switch of the B-phase inverter bridge arm to return to the negative power supply terminal, and then flows sequentially through the C-phase winding and the lower power switch of the C-phase inverter bridge arm to return to the negative power supply terminal.

[0037] Freewheeling path: The freewheeling current starts from the negative power supply terminal, flows sequentially through the parasitic diode of the lower power switch of the A-phase inverter bridge arm and the A-phase winding to reach the neutral point of the three-phase winding, and then flows through the freewheeling diode of the additional bridge arm to reach the neutral point of the three-phase winding. Then, it flows sequentially through the B-phase winding and the parasitic diode of the upper power switch of the B-phase inverter bridge arm to return to the positive power supply terminal, and then flows sequentially through the C-phase winding and the parasitic diode of the upper power switch of the C-phase inverter bridge arm to return to the positive power supply terminal.

[0038] II. Two-phase conduction mode:

[0039] The power switch of the additional bridge arm and two phase windings are turned on, so that the switched reluctance motor enters the two-phase conduction mode. In this mode, the three-phase inverter is controlled by a general method so that the upper power switches of the three-phase inverter bridge arms are turned on alternately, and when the upper power switch of one phase inverter bridge arm is turned on, the lower power switch of the other phase inverter bridge arm is turned on.

[0040] Taking the simultaneous conduction of the upper power switch of phase A inverter bridge arm and the lower power switch of phase B inverter bridge arm as an example, the excitation path, freewheeling path, and two demagnetization paths are as follows:

[0041] Excitation path: The excitation current starts from the positive power supply terminal, flows sequentially through the upper power switch of the A-phase inverter bridge arm and the A-phase winding to the neutral point of the three-phase winding, and then flows through the power switch of the auxiliary bridge arm to the neutral point of the three-phase winding. After that, it flows sequentially through the B-phase winding and the lower power switch of the B-phase inverter bridge arm and returns to the negative power supply terminal.

[0042] Freewheeling path: The freewheeling current starts from the negative power supply terminal, flows sequentially through the parasitic diode of the lower power switch of the A-phase inverter bridge arm and the A-phase winding to reach the neutral point of the three-phase winding, and then flows through the freewheeling diode of the additional bridge arm to reach the neutral point of the three-phase winding. Then it flows sequentially through the B-phase winding and the parasitic diode of the upper power switch of the B-phase inverter bridge arm to return to the positive power supply terminal.

[0043] The first demagnetizing path: The demagnetizing current starts from the negative power supply end, flows sequentially through the parasitic diode of the lower power switch of the A-phase inverter bridge arm and the A-phase winding to the neutral point of the three-phase winding, and then flows through the freewheeling diode of the additional bridge arm to the neutral point of the three-phase winding. After that, it flows sequentially through the B-phase winding and the lower power switch of the B-phase inverter bridge arm and returns to the negative power supply end.

[0044] The second demagnetizing path: The demagnetizing current starts from the positive power supply terminal, flows sequentially through the upper power switch of the A-phase inverter bridge arm and the A-phase winding to the neutral point of the three-phase winding, and then flows through the power switch of the additional bridge arm to the neutral point of the three-phase winding. After that, it flows sequentially through the parasitic diode of the upper power switch of the B-phase inverter bridge arm and returns to the positive power supply terminal.

[0045] III. Single-phase conduction mode:

[0046] The power switch of the additional bridge arm and one phase winding are turned on to enable the switched reluctance motor to enter single-phase conduction mode. In this mode, the three-phase inverter is controlled by a general method to make the lower power switches of the three-phase inverter bridge arm turn on alternately.

[0047] Taking the lower power switch of the B-phase inverter bridge arm as an example, the excitation path and freewheeling path are as follows:

[0048] Excitation path: The excitation current starts from the positive power supply terminal, flows through the power switch of the additional bridge arm to the neutral point of the three-phase winding, and then flows through the B-phase winding and the lower power switch of the B-phase inverter bridge arm in sequence before returning to the negative power supply terminal.

[0049] Freewheeling path: The freewheeling current starts from the negative power supply terminal, flows through the freewheeling diode of the additional bridge arm, reaches the neutral point of the three-phase winding, and then flows sequentially through the parasitic diode of the upper power switch of the B-phase winding and the B-phase inverter bridge arm before returning to the positive power supply terminal.

[0050] Preferably, the general method includes, but is not limited to, a trapezoidal current driving method, a sinusoidal current control method, a magnetic field orientation control method, a space vector control method, or a field weakening speed control method.

[0051] Compared with existing switched reluctance motor drive control circuits, this invention, without changing the structure of the switched reluctance motor, achieves the following advantages by constructing a novel short-tail topology circuit and control strategy: Firstly, the winding current generated by this invention is not a pulsed winding current, but a continuous winding current. Figure 23 The diagram shows the waveform of the winding current when using the trapezoidal current drive method and the space vector control method. The continuous winding current does not fluctuate drastically during commutation, thus effectively reducing the torque ripple of the motor. Secondly, the control strategy of this invention incorporates the axial and radial torque components into the control, thereby effectively reducing the axial and radial noise of the motor.

[0052] This invention effectively solves the problems of large torque pulsation and excessive noise in the axial and radial directions caused by existing switched reluctance motor drive control circuits. It is applicable to electric vehicles, agricultural machinery, heavy machinery, mining machinery, flight equipment, home appliances, military facilities and other fields. Attached Figure Description

[0053] Figure 1 This is the schematic diagram of a traditional asymmetric half-bridge power converter circuit.

[0054] Figure 2 It is a waveform diagram of the unidirectional pulse winding current.

[0055] Figure 3 This is the schematic diagram of a modular converter circuit.

[0056] Figure 4 It is a waveform diagram of the bidirectional pulse winding current.

[0057] Figure 5 This is the first schematic diagram of the short-tail topology circuit in this invention.

[0058] Figure 6 This is the second schematic diagram of the short-tail topology circuit in this invention.

[0059] Figure 7 This is a schematic diagram of the excitation path under the three-phase conduction mode of the first control strategy in this invention.

[0060] Figure 8 This is a schematic diagram of the freewheeling path in the three-phase conduction mode of the first control strategy in this invention.

[0061] Figure 9 This is a schematic diagram of the excitation path under the two-phase conduction mode of the first control strategy in this invention.

[0062] Figure 10 This is a schematic diagram of the freewheeling path in the two-phase conduction mode of the first control strategy in this invention.

[0063] Figure 11 This is a schematic diagram of the first demagnetization path under the two-phase conduction mode of the first control strategy in this invention.

[0064] Figure 12 This is a schematic diagram of the second demagnetization path under the two-phase conduction mode of the first control strategy in this invention.

[0065] Figure 13 This is a schematic diagram of the excitation path in the single-phase conduction mode of the first control strategy in this invention.

[0066] Figure 14 This is a schematic diagram of the freewheeling path in the single-phase conduction mode of the first control strategy in this invention.

[0067] Figure 15 This is a schematic diagram of the excitation path under the three-phase conduction mode of the second control strategy in this invention.

[0068] Figure 16 This is a schematic diagram of the freewheeling path in the three-phase conduction mode of the second control strategy in this invention.

[0069] Figure 17 This is a schematic diagram of the excitation path under the two-phase conduction mode of the second control strategy in this invention.

[0070] Figure 18 This is a schematic diagram of the freewheeling path in the two-phase conduction mode of the second control strategy in this invention.

[0071] Figure 19 This is a schematic diagram of the first demagnetization path under the two-phase conduction mode of the second control strategy in this invention.

[0072] Figure 20 This is a schematic diagram of the second demagnetization path under the two-phase conduction mode of the second control strategy in this invention.

[0073] Figure 21 This is a schematic diagram of the excitation path in the single-phase conduction mode of the second control strategy in this invention.

[0074] Figure 22 This is a schematic diagram of the freewheeling path in the single-phase conduction mode of the second control strategy in this invention.

[0075] Figure 23 This is a waveform diagram of the winding current when the trapezoidal current driving method and the space vector control method are used in this invention.

[0076] Figure 24 This is a schematic diagram illustrating the technological evolution path of the short-tailed topology circuit in this invention.

[0077] In the diagram: the dashed arrows indicate the actual direction of the winding current. Detailed Implementation Example 1

[0078] A short-tail topology circuit suitable for driving a switched reluctance motor includes a switched reluctance motor, an additional bridge arm, and an N-phase inverter bridge arm; N is a positive integer and N≥2;

[0079] Among them, the windings of the switched reluctance motor adopt N-phase windings with star connection;

[0080] The additional bridge arm consists of a freewheeling diode and a power switch connected in series.

[0081] The positive input terminal of the additional bridge arm is connected to the positive power supply terminal; the negative input terminal of the additional bridge arm is connected to the negative power supply terminal; the midpoint of the additional bridge arm is connected to the neutral point of the N-phase winding.

[0082] The positive input terminals of the N-phase inverter bridge arms are all connected to the positive power supply terminals; the negative input terminals of the N-phase inverter bridge arms are all connected to the negative power supply terminals; the midpoints of the N-phase inverter bridge arms are connected one-to-one with the leads of the N-phase windings; the N-phase inverter bridge arms together constitute the N-phase inverter.

[0083] In this embodiment, the cathode of the freewheeling diode of the additional bridge arm serves as the positive input terminal of the additional bridge arm, the anode of the freewheeling diode of the additional bridge arm is connected to the drain of the power switch of the additional bridge arm, and the source of the power switch of the additional bridge arm serves as the negative input terminal of the additional bridge arm. Figure 5 As shown.

[0084] When N=3, the control strategy based on this circuit includes:

[0085] I. Three-phase conduction mode:

[0086] The power switches and three-phase windings of the additional bridge arm are controlled to conduct, enabling the switched reluctance motor to enter the three-phase conduction mode. In this mode, the three-phase inverter is controlled using a general method, so that the upper power switches of the three-phase inverter bridge arms conduct alternately, and when the upper power switch of one phase inverter bridge arm is conducted, the lower power switches of the other two phase inverter bridge arms are conducted; or the lower power switches of the three-phase inverter bridge arms conduct alternately, and when the lower power switch of one phase inverter bridge arm is conducted, the upper power switches of the other two phase inverter bridge arms are conducted.

[0087] Taking the simultaneous conduction of the upper power switch of phase A inverter arm, the lower power switch of phase B inverter arm, and the lower power switch of phase C inverter arm as an example, the excitation path and freewheeling path are as follows:

[0088] Excitation Path: The excitation current starts from the positive power supply terminal, flows sequentially through the upper power switch of the A-phase inverter bridge arm, the A-phase winding, and reaches the neutral point of the three-phase winding. Then, it flows through the power switch of the auxiliary bridge arm and returns to the negative power supply terminal. Simultaneously, it flows sequentially through the B-phase winding and the lower power switch of the B-phase inverter bridge arm, returning to the negative power supply terminal. Thirdly, it flows sequentially through the C-phase winding and the lower power switch of the C-phase inverter bridge arm, returning to the negative power supply terminal. (The text repeats itself here.) Figure 7 As shown;

[0089] Freewheeling current path: The freewheeling current starts from the negative power supply terminal, flows sequentially through the parasitic diode of the lower power switch of the A-phase inverter bridge arm, the A-phase winding, and reaches the neutral point of the three-phase winding. Then, it flows through the freewheeling diode of the additional bridge arm and returns to the positive power supply terminal. On the other hand, it flows sequentially through the B-phase winding and the parasitic diode of the upper power switch of the B-phase inverter bridge arm and returns to the positive power supply terminal. Thirdly, it flows sequentially through the C-phase winding and the parasitic diode of the upper power switch of the C-phase inverter bridge arm and returns to the positive power supply terminal. (The text repeats itself here.) Figure 8 As shown;

[0090] II. Two-phase conduction mode:

[0091] The power switch of the additional bridge arm and two phase windings are turned on, so that the switched reluctance motor enters the two-phase conduction mode. In this mode, the three-phase inverter is controlled by a general method so that the upper power switches of the three-phase inverter bridge arms are turned on alternately, and when the upper power switch of one phase inverter bridge arm is turned on, the lower power switch of the other phase inverter bridge arm is turned on.

[0092] Taking the simultaneous conduction of the upper power switch of phase A inverter bridge arm and the lower power switch of phase B inverter bridge arm as an example, the excitation path, freewheeling path, and two demagnetization paths are as follows:

[0093] Excitation Path: The excitation current starts from the positive power supply terminal, flows sequentially through the upper power switch of the A-phase inverter bridge arm, the A-phase winding, and reaches the neutral point of the three-phase winding. Then, it flows through the power switch of the auxiliary bridge arm and returns to the negative power supply terminal. Simultaneously, it flows sequentially through the B-phase winding and the lower power switch of the B-phase inverter bridge arm before returning to the negative power supply terminal. (Example:) Figure 9 As shown;

[0094] Freewheeling current path: The freewheeling current starts from the negative power supply terminal, flows sequentially through the parasitic diode of the lower power switch of the A-phase inverter bridge arm, the A-phase winding, and reaches the neutral point of the three-phase winding. Then, it flows through the freewheeling diode of the additional bridge arm and returns to the positive power supply terminal. Simultaneously, it flows sequentially through the B-phase winding, the parasitic diode of the upper power switch of the B-phase inverter bridge arm, and returns to the positive power supply terminal. For example... Figure 10 As shown;

[0095] The first demagnetizing path: The demagnetizing current starts from the negative power supply terminal, flows sequentially through the parasitic diode of the lower power switch of the A-phase inverter bridge arm, the A-phase winding, and reaches the neutral point of the three-phase winding. Then, it flows through the power switch of the additional bridge arm and returns to the negative power supply terminal, and simultaneously flows sequentially through the B-phase winding and the lower power switch of the B-phase inverter bridge arm and returns to the negative power supply terminal. Figure 11 As shown;

[0096] The second demagnetizing path: The demagnetizing current starts from the positive power supply terminal, flows sequentially through the upper power switch of the A-phase inverter bridge arm, the A-phase winding, and reaches the neutral point of the three-phase winding. Then, it flows through the freewheeling diode of the additional bridge arm and returns to the positive power supply terminal. Simultaneously, it flows sequentially through the B-phase winding, the parasitic diode of the upper power switch of the B-phase inverter bridge arm, and returns to the positive power supply terminal. For example... Figure 12 As shown;

[0097] III. Single-phase conduction mode:

[0098] The power switch of the additional bridge arm and one phase winding are turned on to enable the switched reluctance motor to enter single-phase conduction mode. In this mode, the three-phase inverter is controlled by a general method to make the upper power switches of the three-phase inverter bridge arm turn on alternately.

[0099] Taking the conduction of the upper power switch of the A-phase inverter bridge arm as an example, the excitation path and freewheeling path are as follows:

[0100] Excitation path: The excitation current starts from the positive power supply terminal, flows sequentially through the upper power switch of the A-phase inverter bridge arm, the A-phase winding, and reaches the neutral point of the three-phase winding. Then it flows through the power switch of the additional bridge arm and returns to the negative power supply terminal, as shown below. Figure 13 As shown;

[0101] Freewheeling current path: The freewheeling current starts from the negative power supply terminal, flows sequentially through the parasitic diode of the lower power switch of the A-phase inverter bridge arm, the A-phase winding, and reaches the neutral point of the three-phase winding. Then it flows through the freewheeling diode of the additional bridge arm and returns to the positive power supply terminal, as shown below. Figure 14 As shown.

[0102] The general methods include, but are not limited to, trapezoidal current driving methods, sinusoidal current control methods, magnetic field orientation control methods, space vector control methods, or magnetic weakening speed control methods. Example 2

[0103] A short-tail topology circuit suitable for driving a switched reluctance motor includes a switched reluctance motor, an additional bridge arm, and an N-phase inverter bridge arm; N is a positive integer and N≥2;

[0104] Among them, the windings of the switched reluctance motor adopt N-phase windings with star connection;

[0105] The additional bridge arm consists of a freewheeling diode and a power switch connected in series.

[0106] The positive input terminal of the additional bridge arm is connected to the positive power supply terminal; the negative input terminal of the additional bridge arm is connected to the negative power supply terminal; the midpoint of the additional bridge arm is connected to the neutral point of the N-phase winding.

[0107] The positive input terminals of the N-phase inverter bridge arms are all connected to the positive power supply terminals; the negative input terminals of the N-phase inverter bridge arms are all connected to the negative power supply terminals; the midpoints of the N-phase inverter bridge arms are connected one-to-one with the leads of the N-phase windings; the N-phase inverter bridge arms together constitute the N-phase inverter.

[0108] In this embodiment, the drain of the power switch of the additional bridge arm serves as the positive input terminal of the additional bridge arm, the source of the power switch of the additional bridge arm is connected to the cathode of the freewheeling diode of the additional bridge arm, and the anode of the freewheeling diode of the additional bridge arm serves as the negative input terminal of the additional bridge arm. Figure 6 As shown.

[0109] When N=3, the control strategy based on this circuit includes:

[0110] I. Three-phase conduction mode:

[0111] The power switches and three-phase windings of the additional bridge arm are controlled to conduct, enabling the switched reluctance motor to enter the three-phase conduction mode. In this mode, the three-phase inverter is controlled using a general method, so that the upper power switches of the three-phase inverter bridge arms conduct alternately, and when the upper power switch of one phase inverter bridge arm is conducted, the lower power switches of the other two phase inverter bridge arms are conducted; or the lower power switches of the three-phase inverter bridge arms conduct alternately, and when the lower power switch of one phase inverter bridge arm is conducted, the upper power switches of the other two phase inverter bridge arms are conducted.

[0112] Taking the simultaneous conduction of the upper power switch of phase A inverter arm, the lower power switch of phase B inverter arm, and the lower power switch of phase C inverter arm as an example, the excitation path and freewheeling path are as follows:

[0113] Excitation path: The excitation current starts from the positive power supply terminal, flowing sequentially through the upper power switch of the A-phase inverter bridge arm and the A-phase winding to reach the neutral point of the three-phase winding. Simultaneously, it flows through the power switch of the auxiliary bridge arm to reach the neutral point of the three-phase winding. Then, it flows sequentially through the B-phase winding and the lower power switch of the B-phase inverter bridge arm, returning to the negative power supply terminal. Similarly, it flows sequentially through the C-phase winding and the lower power switch of the C-phase inverter bridge arm, returning to the negative power supply terminal. (The text repeats itself here.) Figure 15 As shown;

[0114] Freewheeling current path: The freewheeling current starts from the negative power supply terminal, flowing sequentially through the parasitic diode of the lower power switch of the A-phase inverter bridge arm, and then through the A-phase winding to reach the neutral point of the three-phase winding. Simultaneously, it flows through the freewheeling diode of the additional bridge arm to reach the neutral point of the three-phase winding. Then, it flows sequentially through the B-phase winding and the parasitic diode of the upper power switch of the B-phase inverter bridge arm before returning to the positive power supply terminal. Similarly, it flows sequentially through the C-phase winding and the parasitic diode of the upper power switch of the C-phase inverter bridge arm before returning to the positive power supply terminal. (The text repeats itself here.) Figure 16 As shown;

[0115] II. Two-phase conduction mode:

[0116] The power switch of the additional bridge arm and two phase windings are turned on, so that the switched reluctance motor enters the two-phase conduction mode. In this mode, the three-phase inverter is controlled by a general method so that the upper power switches of the three-phase inverter bridge arms are turned on alternately, and when the upper power switch of one phase inverter bridge arm is turned on, the lower power switch of the other phase inverter bridge arm is turned on.

[0117] Taking the simultaneous conduction of the upper power switch of phase A inverter bridge arm and the lower power switch of phase B inverter bridge arm as an example, the excitation path, freewheeling path, and two demagnetization paths are as follows:

[0118] Excitation Path: The excitation current starts from the positive power supply terminal, flowing sequentially through the upper power switch of the A-phase inverter bridge arm and the A-phase winding to reach the neutral point of the three-phase winding. Simultaneously, it flows through the power switch of the auxiliary bridge arm to reach the neutral point of the three-phase winding, then sequentially through the B-phase winding and the lower power switch of the B-phase inverter bridge arm before returning to the negative power supply terminal. Figure 17 As shown;

[0119] Freewheeling current path: The freewheeling current starts from the negative power supply terminal, flowing sequentially through the parasitic diode of the lower power switch of the A-phase inverter bridge arm, and then through the A-phase winding to reach the neutral point of the three-phase winding. Simultaneously, it flows through the freewheeling diode of the additional bridge arm to reach the neutral point of the three-phase winding, then sequentially through the B-phase winding, and finally through the parasitic diode of the upper power switch of the B-phase inverter bridge arm before returning to the positive power supply terminal, as shown below. Figure 18 As shown;

[0120] The first demagnetizing path: The demagnetizing current starts from the negative power supply terminal, flowing sequentially through the parasitic diode of the lower power switch of the A-phase inverter bridge arm, and then through the A-phase winding to reach the neutral point of the three-phase winding. Simultaneously, it flows through the freewheeling diode of the additional bridge arm to reach the neutral point of the three-phase winding, then sequentially through the B-phase winding and the lower power switch of the B-phase inverter bridge arm before returning to the negative power supply terminal. Figure 19 As shown;

[0121] The second demagnetizing path: The demagnetizing current starts from the positive power supply terminal, flowing sequentially through the upper power switch of the A-phase inverter bridge arm and the A-phase winding to reach the neutral point of the three-phase winding. Simultaneously, it flows through the power switch of the additional bridge arm to reach the neutral point of the three-phase winding, then sequentially through the B-phase winding and the parasitic diode of the upper power switch of the B-phase inverter bridge arm before returning to the positive power supply terminal. Figure 20 As shown;

[0122] III. Single-phase conduction mode:

[0123] The power switch of the additional bridge arm and one phase winding are turned on to enable the switched reluctance motor to enter single-phase conduction mode. In this mode, the three-phase inverter is controlled by a general method to make the lower power switches of the three-phase inverter bridge arm turn on alternately.

[0124] Taking the lower power switch of the B-phase inverter bridge arm as an example, the excitation path and freewheeling path are as follows:

[0125] Excitation path: The excitation current starts from the positive power supply terminal, flows through the power switch of the additional bridge arm to the neutral point of the three-phase winding, and then flows sequentially through the B-phase winding, the lower power switch of the B-phase inverter bridge arm, and returns to the negative power supply terminal, as shown below. Figure 21 As shown;

[0126] Freewheeling current path: The freewheeling current starts from the negative power supply terminal, flows through the freewheeling diode of the additional bridge arm, reaches the neutral point of the three-phase winding, and then flows sequentially through the B-phase winding, the parasitic diode of the upper power switch of the B-phase inverter bridge arm, and returns to the positive power supply terminal, as shown below. Figure 22 As shown.

[0127] The general methods include, but are not limited to, trapezoidal current driving methods, sinusoidal current control methods, magnetic field orientation control methods, space vector control methods, or magnetic weakening speed control methods.

[0128] The technological evolution path of the short-tailed topology circuit in this invention is as follows: Figure 24 As shown:

[0129] Figure 24 The initial concept of this invention is as follows: The three-phase windings of a switched reluctance motor are connected in a star configuration. The leads of the three-phase windings are then connected to a three-phase inverter. Simultaneously, the neutral point of the three-phase windings is connected to an inertial device (an inductor in the diagram). A full-bridge circuit is connected across the inertial device to control the current flowing through it, thereby controlling the neutral point current. The purpose of this approach is to achieve consistency in the current direction across each phase winding by controlling the neutral point current, thus realizing unipolar excitation of each phase winding.

[0130] Figure 24 b is based on Figure 24 The improvement approach for a is due to the following reasons: Figure 24 The approach in section a determines that the direction of the current flowing through the inertial device remains consistent, therefore it can be... Figure 24 The full-bridge circuit in section a is improved to an asymmetrical half-bridge circuit. This improvement can reduce the number of power switches in the circuit while still maintaining control over the direction of the neutral point current.

[0131] Figure 24 c is based on Figure 24 The improvement idea for b is to... Figure 24 In step b, the inertial devices are eliminated, and the asymmetrical half-bridge circuit is optimized into an additional bridge arm composed of two power switches to directly control the neutral point current, thereby ensuring unipolar excitation of each phase winding, that is, ensuring that the current direction in each phase winding remains consistent.

[0132] Figure 24 d and Figure 24 e is based on Figure 24 The final evolution of c is the short-tailed topology circuit in this invention. Since the neutral point current direction is fixed, therefore... Figure 24 In bridge c, one of the power switches in the additional bridge arm will always be in the off state, with only its parasitic diode providing freewheeling. Therefore, the power switch can be adjusted according to the direction of the winding current. Figure 24 In section c, one of the power switches in the additional bridge arm is replaced with a freewheeling diode, further reducing the number of power switches and the complexity of the circuit topology and control. Figure 24 The direction of the neutral point current in d is from right to left. Figure 24 The neutral point current in equation e flows from left to right, the difference being: Figure 24 In step d, the winding current originates from the upper half of the inverter bridge arm, and the neutral point current is passively controlled by the additional bridge arm. Figure 24 In step e, the winding current originates from the additional bridge arm, and the power switch of the additional bridge arm actively controls the neutral point current. Figure 24 d and Figure 24 The basic control scheme and operating principle of e are the same, the difference lies in the control process of the neutral point current and the excitation source of the winding current.

[0133] The advantages of the short-tail topology circuit in this invention are as follows: It uses a freewheeling diode or a circuit that performs the same function to replace the power switch that does not perform the switching function. This reduces the hardware cost of the additional bridge arm and further improves the integration of the entire drive circuit. It also reduces the losses of the power switching devices in the additional bridge arm. Only a single power switch needs to be controlled in the additional bridge arm, reducing the computational burden on the controller chip and simplifying the control flow of the drive circuit. Simultaneously, the additional bridge arm can still cooperate with the three-phase inverter to provide unipolar excitation to each phase winding. In both motor and generator modes, it can simultaneously ensure the unidirectionality of the winding current, expanding the range of control methods that the circuit can adapt to. In motor mode, by controlling the power switch of the additional bridge arm, the direction of the neutral point current and the amplitude of the neutral point current can be adjusted. The freewheeling diode in the additional bridge arm provides freewheeling and limits the direction of the neutral point current. In generator mode, when the power switch of the auxiliary arm is turned on, it works with the three-phase inverter to excite each phase winding. When the power switch of the auxiliary arm is turned off, the current of the energized winding is applied to the generator load through the freewheeling diode of the auxiliary arm, realizing the unidirectional current generation process.

[0134] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A topology circuit suitable for driving a switched reluctance motor, characterized by: The circuit comprises a switched reluctance motor, an additional bridge arm, and N-phase inverter bridge arms; N=3; The windings of the switched reluctance motor are N-phase windings connected in star; The additional bridge arm is formed by a freewheeling diode and a power switch connected in series; The positive input end of the additional bridge arm is connected with the positive power supply end; the negative input end of the additional bridge arm is connected with the negative power supply end; and the midpoint of the additional bridge arm is connected with the neutral point of the N-phase windings; The positive input ends of the N-phase inverter bridge arms are all connected with the positive power supply end; the negative input ends of the N-phase inverter bridge arms are all connected with the negative power supply end; and the midpoints of the N-phase inverter bridge arms are connected with the lead-out ends of the N-phase windings in one-to-one correspondence; and the N-phase inverter bridge arms jointly constitute an N-phase inverter; The cathode of the freewheeling diode of the additional bridge arm serves as the positive input end of the additional bridge arm; the anode of the freewheeling diode of the additional bridge arm is connected with the drain of the power switch of the additional bridge arm; and the source of the power switch of the additional bridge arm serves as the negative input end of the additional bridge arm; The control strategy based on the circuit comprises: First, a three-phase conduction mode: The power switch of the additional bridge arm and the three-phase windings are controlled to be conducted, so that the switched reluctance motor enters the three-phase conduction mode; in this mode, a general method is used to control the three-phase inverter, so that the upper power switches of the three-phase inverter bridge arms are alternately conducted, and when the upper power switch of one of the inverter bridge arms is conducted, the lower power switches of the other two inverter bridge arms are conducted; or so that the lower power switches of the three-phase inverter bridge arms are alternately conducted, and when the lower power switch of one of the inverter bridge arms is conducted, the upper power switches of the other two inverter bridge arms are conducted; When the upper power switch of the A-phase inverter bridge arm, the lower power switch of the B-phase inverter bridge arm, and the lower power switch of the C-phase inverter bridge arm are simultaneously conducted, the excitation path and the freewheeling path are as follows: The excitation path: the excitation current starts from the positive power supply end, sequentially flows through the upper power switch of the A-phase inverter bridge arm, the A-phase winding, and then reaches the neutral point of the three-phase windings, and then on one hand flows through the power switch of the additional bridge arm back to the negative power supply end, on the other hand sequentially flows through the B-phase winding and the lower power switch of the B-phase inverter bridge arm back to the negative power supply end, and on the third hand sequentially flows through the C-phase winding and the lower power switch of the C-phase inverter bridge arm back to the negative power supply end; The freewheeling path: the freewheeling current starts from the negative power supply end, sequentially flows through the parasitic diode of the lower power switch of the A-phase inverter bridge arm, the A-phase winding, and then reaches the neutral point of the three-phase windings, and then on one hand flows through the freewheeling diode of the additional bridge arm back to the positive power supply end, on the other hand sequentially flows through the parasitic diode of the upper power switch of the B-phase inverter bridge arm back to the positive power supply end, and on the third hand sequentially flows through the parasitic diode of the upper power switch of the C-phase inverter bridge arm back to the positive power supply end; Second, a two-phase conduction mode: The power switch of the additional bridge arm and two of the phase windings are controlled to be conducted, so that the switched reluctance motor enters the two-phase conduction mode; in this mode, a general method is used to control the three-phase inverter, so that the upper power switches of the three-phase inverter bridge arms are alternately conducted, and when the upper power switch of one of the inverter bridge arms is conducted, the lower power switch of the other inverter bridge arm is conducted. When the upper power switch of the A-phase inverter arm and the lower power switch of the B-phase inverter arm are turned on at the same time, the excitation path, the freewheeling path and the two demagnetization paths are as follows: The excitation path: the excitation current starts from the positive power supply end, sequentially flows through the upper power switch of the A-phase inverter arm, the A-phase winding, and then reaches the neutral point of the three-phase winding, and then flows through the power switch of the additional arm to return to the negative power supply end on the one hand, and sequentially flows through the B-phase winding and the lower power switch of the B-phase inverter arm to return to the negative power supply end on the other hand; The freewheeling path: the freewheeling current starts from the negative power supply end, sequentially flows through the parasitic diode of the lower power switch of the A-phase inverter arm and the A-phase winding, and then reaches the neutral point of the three-phase winding, and then flows through the freewheeling diode of the additional arm to return to the positive power supply end on the one hand, and sequentially flows through the B-phase winding and the parasitic diode of the upper power switch of the B-phase inverter arm to return to the positive power supply end on the other hand; The first demagnetization path: the demagnetization current starts from the negative power supply end, sequentially flows through the parasitic diode of the lower power switch of the A-phase inverter arm and the A-phase winding, and then reaches the neutral point of the three-phase winding, and then flows through the power switch of the additional arm to return to the negative power supply end on the one hand, and sequentially flows through the B-phase winding and the lower power switch of the B-phase inverter arm to return to the negative power supply end on the other hand; The second demagnetization path: the demagnetization current starts from the positive power supply end, sequentially flows through the upper power switch of the A-phase inverter arm and the A-phase winding, and then reaches the neutral point of the three-phase winding, and then flows through the freewheeling diode of the additional arm to return to the positive power supply end on the one hand, and sequentially flows through the B-phase winding and the parasitic diode of the upper power switch of the B-phase inverter arm to return to the positive power supply end on the other hand; III. Single-phase conduction mode: The power switch of the additional arm and one of the phase windings are turned on to make the switched reluctance motor enter the single-phase conduction mode; in this mode, the three-phase inverter is controlled by a general method to make the upper power switches of the three-phase inverter arms turn on alternately; When the upper power switch of the A-phase inverter arm is turned on, the excitation path and the freewheeling path are as follows: The excitation path: the excitation current starts from the positive power supply end, sequentially flows through the upper power switch of the A-phase inverter arm and the A-phase winding, and then reaches the neutral point of the three-phase winding, and then flows through the power switch of the additional arm to return to the negative power supply end; The freewheeling path: the freewheeling current starts from the negative power supply end, sequentially flows through the parasitic diode of the lower power switch of the A-phase inverter arm and the A-phase winding, and then reaches the neutral point of the three-phase winding, and then flows through the freewheeling diode of the additional arm to return to the positive power supply end.

2. A topology circuit suitable for driving a switched reluctance motor, characterized by: It comprises a switched reluctance motor, an additional arm and N-phase inverter arms; N=3; The windings of the switched reluctance motor are N-phase windings connected in star; The additional arm is composed of a freewheeling diode and a power switch connected in series; The positive input end of the additional arm is connected with the positive power supply end; the negative input end of the additional arm is connected with the negative power supply end; the midpoint of the additional arm is connected with the neutral point of the N-phase windings; The positive input ends of the N-phase inverter arms are all connected with the positive power supply end; the negative input ends of the N-phase inverter arms are all connected with the negative power supply end; the midpoints of the N-phase inverter arms are connected with the lead-out ends of the N-phase windings one by one; the N-phase inverter arms together constitute an N-phase inverter; The drain of the power switch of the additional bridge arm is used as a positive input terminal of the additional bridge arm, the source of the power switch of the additional bridge arm is connected with the cathode of the freewheeling diode of the additional bridge arm, and the anode of the freewheeling diode of the additional bridge arm is used as a negative input terminal of the additional bridge arm; The control strategy based on the circuit comprises: One, three-phase conduction mode: The power switch of the additional bridge arm and the three-phase winding are controlled to be conducted, so that the switched reluctance motor enters the three-phase conduction mode; in the mode, a general method is used to control the three-phase inverter, so that the upper power switches of the three-phase inverter arms are alternately conducted, and when the upper power switch of one of the three-phase inverter arms is conducted, the lower power switches of the other two-phase inverter arms are conducted; or the lower power switches of the three-phase inverter arms are alternately conducted, and when the lower power switch of one of the three-phase inverter arms is conducted, the upper power switches of the other two-phase inverter arms are conducted; When the upper power switch of the A-phase inverter arm, the lower power switch of the B-phase inverter arm and the lower power switch of the C-phase inverter arm are simultaneously conducted, the excitation path and the freewheeling path are as follows: The excitation path: the excitation current starts from the positive power supply terminal, flows through the upper power switch of the A-phase inverter arm and the A-phase winding in turn, reaches the neutral point of the three-phase winding, flows through the power switch of the additional bridge arm, and then flows through the B-phase winding and the lower power switch of the B-phase inverter arm in turn to return to the negative power supply terminal, and flows through the C-phase winding and the lower power switch of the C-phase inverter arm in turn to return to the negative power supply terminal; The freewheeling path: the freewheeling current starts from the negative power supply terminal, flows through the parasitic diode of the lower power switch of the A-phase inverter arm and the A-phase winding in turn, reaches the neutral point of the three-phase winding, flows through the freewheeling diode of the additional bridge arm, and then flows through the parasitic diode of the upper power switch of the B-phase inverter arm and the B-phase winding in turn to return to the positive power supply terminal, and flows through the parasitic diode of the upper power switch of the C-phase inverter arm and the C-phase winding in turn to return to the positive power supply terminal; Two, two-phase conduction mode: The power switch of the additional bridge arm and two of the three-phase windings are controlled to be conducted, so that the switched reluctance motor enters the two-phase conduction mode; in the mode, a general method is used to control the three-phase inverter, so that the upper power switches of the three-phase inverter arms are alternately conducted, and when the upper power switch of one of the three-phase inverter arms is conducted, the lower power switch of the other one of the three-phase inverter arms is conducted; When the upper power switch of the A-phase inverter arm and the lower power switch of the B-phase inverter arm are simultaneously conducted, the excitation path, the freewheeling path and the two demagnetization paths are as follows: The excitation path: the excitation current starts from the positive power supply terminal, flows through the upper power switch of the A-phase inverter arm and the A-phase winding in turn, reaches the neutral point of the three-phase winding, flows through the power switch of the additional bridge arm, and then flows through the B-phase winding and the lower power switch of the B-phase inverter arm in turn to return to the negative power supply terminal; The freewheeling path: the freewheeling current starts from the negative power supply end, flows through the parasitic diode of the lower power switch of the A-phase inverter bridge arm, the A-phase winding, and then reaches the neutral point of the three-phase winding, and then flows through the freewheeling diode of the additional bridge arm, and then reaches the neutral point of the three-phase winding, and then flows through the B-phase winding and the parasitic diode of the upper power switch of the B-phase inverter bridge arm in sequence, and then returns to the positive power supply end; The first demagnetization path: the demagnetization current starts from the negative power supply end, flows through the parasitic diode of the lower power switch of the A-phase inverter bridge arm, the A-phase winding, and then reaches the neutral point of the three-phase winding, and then flows through the freewheeling diode of the additional bridge arm, and then reaches the neutral point of the three-phase winding, and then flows through the B-phase winding and the lower power switch of the B-phase inverter bridge arm in sequence, and then returns to the negative power supply end; The second demagnetization path: the demagnetization current starts from the positive power supply end, flows through the upper power switch of the A-phase inverter bridge arm and the A-phase winding in sequence, and then reaches the neutral point of the three-phase winding, and then flows through the power switch of the additional bridge arm, and then reaches the neutral point of the three-phase winding, and then flows through the B-phase winding and the parasitic diode of the upper power switch of the B-phase inverter bridge arm in sequence, and then returns to the positive power supply end; III. Single-phase conduction mode: The power switch of the additional bridge arm and one of the three-phase windings are controlled to be turned on, so that the switched reluctance motor enters the single-phase conduction mode; in this mode, the general method is used to control the three-phase inverter, so that the lower power switches of the three-phase inverter bridge arms are turned on alternately; When the lower power switch of the B-phase inverter bridge arm is turned on, the excitation path and the freewheeling path are as follows: The excitation path: the excitation current starts from the positive power supply end, flows through the power switch of the additional bridge arm, and then reaches the neutral point of the three-phase winding, and then flows through the B-phase winding and the lower power switch of the B-phase inverter bridge arm in sequence, and then returns to the negative power supply end; The freewheeling path: the freewheeling current starts from the negative power supply end, flows through the freewheeling diode of the additional bridge arm, and then reaches the neutral point of the three-phase winding, and then flows through the B-phase winding and the parasitic diode of the upper power switch of the B-phase inverter bridge arm in sequence, and then returns to the positive power supply end.

3. A topology circuit suitable for driving a switched reluctance motor according to claim 1 or 2, characterized in that: The general method includes but is not limited to the trapezoidal current driving method or the sinusoidal current control method or the magnetic field oriented control method or the space vector control method or the field weakening control method.

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