Drive circuit, motor system, and switched reluctance motor

Abstract

A drive circuit (1) comprises three arms (10) connected in parallel to a first input terminal (61) and a second input terminal (62) of a power supply (6). Each of the three arms (10) is formed of a series circuit of a first semiconductor switch (S1), a second semiconductor switch (S2), and a diode (D3). The first semiconductor switch (S1) is connected to the first input terminal (61) and has a first regenerative diode (D1). The second semiconductor switch (S2) is connected to the second input terminal (62) and has a second regenerative diode (D2). The diode (D3) is connected between the first semiconductor switch (S1) and the second semiconductor switch (S2).

Description

[Technical Field]

[0001] The present invention relates to a drive circuit for driving a switched reluctance motor, a motor system including the drive circuit, and a switched reluctance motor used in the motor system. [Background technology]

[0002] Patent Document 1 discloses a switched reluctance motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-147778 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a drive circuit, a motor system, and a switched reluctance motor that can reduce manufacturing costs while maintaining the drive performance of the switched reluctance motor. [Means for solving the problem]

[0005] To achieve the above object, a drive circuit according to one aspect of the present invention includes three arms connected in parallel to a first input terminal and a second input terminal of a power supply. Each of the three arms is configured as a series circuit of a first semiconductor switch, a second semiconductor switch, and a diode. The first semiconductor switch is connected to the first input terminal and has a first regenerative diode. The second semiconductor switch is connected to the second input terminal and has a second regenerative diode. The diode is connected between the first semiconductor switch and the second semiconductor switch. A plurality of coils of a stator of a switched reluctance motor can be connected to each of the three arms. The drive circuit rotates the rotor of the switched reluctance motor by passing a current through each of the plurality of coils to excite them.

[0006] In order to achieve the above object, a motor system according to one aspect of the present invention includes the drive circuit and the switched reluctance motor driven by the drive circuit that receives power from the power supply.

[0007] To achieve the above object, a switched reluctance motor according to one embodiment of the present invention includes a stator and a rotor. The stator has multiple pairs of first salient poles to which multiple coils are respectively attached. The rotor has multiple second salient poles and rotates by passing a current through each of the multiple coils to excite them. The multiple coils are connected to each other to form a closed loop. [Effects of the Invention]

[0008] The present invention provides a drive circuit, a motor system, and a switched reluctance motor that can reduce manufacturing costs while maintaining the drive performance of the switched reluctance motor. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a circuit diagram showing the configuration of a motor system including a drive circuit according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of a switched reluctance motor according to an embodiment. [Figure 3] FIG. 3 is a circuit diagram illustrating an example of the operation of the drive circuit according to the embodiment. [Figure 4] FIG. 4 is a circuit diagram showing an example of the operation of the drive circuit according to the embodiment. [Figure 5] FIG. 5 is a circuit diagram showing an example of the operation of the drive circuit according to the embodiment. [Figure 6] FIG. 6 is a circuit diagram showing the configuration of a drive circuit of a comparative example. [Figure 7A] FIG. 7A is a waveform diagram showing torque of the switched reluctance motor according to the embodiment in discontinuous conduction mode. [Figure 7B] FIG. 7B is a waveform diagram showing torque of the switched reluctance motor according to the embodiment in the continuous conduction mode. [Figure 8A] FIG. 8A is a waveform diagram showing a current flowing through any one coil of the switched reluctance motor according to the embodiment in a discontinuous conduction mode. [Figure 8B] FIG. 8B is a waveform diagram showing a current flowing through any one coil of the switched reluctance motor according to the embodiment in the continuous conduction mode. [Figure 9] FIG. 9 is a circuit diagram showing a drive circuit according to an embodiment and another example of a switched reluctance motor according to an embodiment. [Figure 10] FIG. 10 is a circuit diagram showing a drive circuit of a comparative example and another example of a switched reluctance motor according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present invention. Numerical values, shapes, methods, components, component connection forms, steps, step orders, etc. shown in the following embodiments are merely examples and are not intended to limit the present invention. Furthermore, in each drawing, substantially identical components are assigned the same reference numerals, and duplicated descriptions may be omitted or simplified.

[0011] [1. Configuration] As shown in Fig. 1, a drive circuit 1 according to the embodiment is a circuit for driving a switched reluctance motor 3. Fig. 1 is a circuit diagram showing the configuration of a motor system 100 including the drive circuit 1 according to the embodiment. The drive circuit 1, together with the switched reluctance motor 3, constitutes the motor system 100. In other words, the motor system 100 includes the drive circuit 1 and the switched reluctance motor 3 that is driven by the drive circuit 1 that receives power from a power source 6. In other words, the switched reluctance motor 3 is driven by the drive circuit 1 that receives power from the power source 6.

[0012] [1-1. Switched reluctance motor] First, the configuration of a switched reluctance motor 3 according to an embodiment will be described with reference to Fig. 2. Fig. 2 is a schematic diagram showing the configuration of a switched reluctance motor 3 according to an embodiment. The switched reluctance motor 3 includes a stator 4 and a rotor 5. In this embodiment, the switched reluctance motor 3 is a motor in which the stator 4 has 12 poles and the rotor 5 has 10 poles.

[0013] The stator 4 has a main body 41, a plurality of first salient poles (teeth) 42, and a plurality of coils L0. As described above, in the embodiment, the stator 4 has 12 poles, and therefore the number of first salient poles 42 is 12.

[0014] The main body 41 has a circular ring shape in a plan view and is made of a magnetic material such as a non-oriented silicon steel plate. The "plan view" here refers to the switched reluctance motor 3 viewed from the axial direction of a drive shaft 53 (described later).

[0015] The multiple first salient poles 42 are rectangular in plan view and are formed integrally with the main body 41 so as to protrude radially inward from the inner surface of the main body 41. The multiple first salient poles 42 are arranged at equal intervals in the circumferential direction of the main body 41. A coil L0 is attached to each first salient pole 42 by concentrated winding of a conductor wire. In this embodiment, a pair of first salient poles 42 that face each other across the rotor 5 in plan view are attached with a coil L0 through which the same phase current flows. The coils L0 attached to each of the pair of first salient poles 42 may be connected in series or in parallel.

[0016] Specifically, as shown in FIG. 2, a pair of first salient poles 42 marked with an "A" are each attached with a first coil L1 (also referred to as "coil A"), and a pair of first salient poles 42 marked with a "B" are each attached with a second coil L2 (also referred to as "coil B"). A pair of first salient poles 42 marked with a "C" are each attached with a third coil L3 (also referred to as "coil C"), and a pair of first salient poles 42 marked with a "D" are each attached with a fourth coil L4 (also referred to as "coil D"). A pair of first salient poles 42 marked with an "E" are each attached with a fifth coil L5 (also referred to as "coil E"), and a pair of first salient poles 42 marked with an "F" are each attached with a sixth coil L6 (also referred to as "coil F"). In other words, there are six coils L0.

[0017] As described above, the stator 4 has a plurality of pairs of first salient poles 42, to which a plurality of coils L0 are respectively attached. The number of pairs of first salient poles 42 is an integer multiple of six.

[0018] 1, the coils L0 are connected to one another at a neutral point N1. That is, one end of each of the first coil L1 (coil A), the second coil L2 (coil B), the third coil L3 (coil C), the fourth coil L4 (coil D), the fifth coil L5 (coil E), and the sixth coil L6 (coil F) is connected to the same neutral point N1.

[0019] The rotor 5 is located inside the stator 4 and is rotatable relative to the stator 4. The rotor 5 has a main body 51, a plurality of second salient poles (teeth) 52, and a drive shaft 53. As described above, in this embodiment, the rotor 5 has ten poles, and therefore the number of second salient poles 52 is ten. In other words, the number of second salient poles 52 is an integer multiple of five.

[0020] The main body 51 has a circular shape in a plan view, and is made of a magnetic material such as a non-oriented silicon steel plate.

[0021] The second salient poles 52 are rectangular in plan view and are formed integrally with the main body 51 so as to protrude radially outward from the outer surface of the main body 51. The second salient poles 52 are arranged at equal intervals in the circumferential direction of the main body 51.

[0022] The drive shaft 53 is a long rod-like member that passes through the center of the main body 51 in a plan view, extends along the thickness direction of the main body 51, and is formed integrally with the main body 51. The drive shaft 53 rotates as the rotor 5 rotates.

[0023] Here, we will briefly explain the operating principle of the switched reluctance motor 3. When current is supplied from the drive circuit 1 and one or more coils L0 in the stator 4 are excited, the magnetic flux generated by the one or more coils L0 acts on the rotor 5 to minimize magnetic resistance. At this time, the second salient pole 52 located near one or more first salient poles 42 to which one or more coils L0 are attached is attracted to the first salient pole 42 so as to move to a position facing the first salient pole 42. As the drive circuit 1 sequentially excites the multiple coils L0, the second salient pole 52 is repeatedly attracted to the first salient pole 42 and moves, causing the rotor 5 to rotate relative to the stator 4.

[0024] [1-2. Drive circuit] Next, the configuration of a drive circuit 1 according to an embodiment will be described with reference to Fig. 1. The drive circuit 1 includes three arms 10 and a control circuit 2. Note that the drive circuit 1 only needs to include at least three arms 10, and does not necessarily need to include the control circuit 2. In other words, the control circuit 2 may be an additional component to the drive circuit 1.

[0025] The three arms 10 are connected in parallel to a first input terminal 61 and a second input terminal 62 of a power supply 6. In this embodiment, the power supply 6 is a DC power supply, and applies a DC voltage between the first input terminal 61 and the second input terminal 62. In this embodiment, the first input terminal 61 is at a positive potential, and the second input terminal 62 is connected to ground.

[0026] Each of the three arms 10 is configured with a series circuit of a first semiconductor switch S1, a second semiconductor switch S2, and a diode D3. The first semiconductor switch S1 is connected to a first input terminal 61 and has a first regenerative diode D1. The second semiconductor switch S2 is connected to a second input terminal 62 and has a second regenerative diode D2. The diode D3 is connected between the first semiconductor switch S1 and the second semiconductor switch S2. In this embodiment, the anode of the diode D3 is connected to the second semiconductor switch S2 and the cathode is connected to the first semiconductor switch S1.

[0027] The first semiconductor switch S1 and the second semiconductor switch S2 are, for example, n-channel enhancement-type metal-oxide-semiconductor field-effect transistors (MOSFETs) or insulated gate bipolar transistors (Insulated Gate Bipolar Transistors). In this embodiment, the first semiconductor switch S1 and the second semiconductor switch S2 are MOSFETs. Therefore, the first regenerative diode D1 is a parasitic diode of the first semiconductor switch S1, and the second regenerative diode D2 is a parasitic diode of the second semiconductor switch S2. Note that the first semiconductor switch S1 and the second semiconductor switch S2 are not limited to MOSFETs or insulated gate bipolar transistors, and may be, for example, junction field-effect transistors (FETs). In this case, the first regenerative diode D1 may be an external diode connected between the drain and source of the first semiconductor switch S1, and the second regenerative diode D2 may be an external diode connected between the drain and source of the second semiconductor switch S2.

[0028] A plurality of coils L0 of the stator 4 of the switched reluctance motor 3 can be connected to each of the three arms 10. The drive circuit 1 then passes a current through each of the plurality of coils L0 to excite them, thereby rotating the rotor 5 of the switched reluctance motor 3.

[0029] The configuration of the drive circuit 1 will be described in more detail below. For ease of explanation, the leftmost arm 10 of the three arms 10 will be referred to as the "first arm 11," the middle arm 10 as the "second arm 12," and the rightmost arm 10 as the "third arm 13." For ease of explanation, the first semiconductor switch S1 of the first arm 11 will be referred to as the "switch A," the second semiconductor switch S2 of the first arm 11 as the "switch D," the first semiconductor switch S1 of the second arm 12 as the "switch B," the second semiconductor switch S2 as the "switch E," the first semiconductor switch S1 of the third arm 13 as the "switch C," and the second semiconductor switch S2 as the "switch F." For ease of explanation, the diode D3 of the first arm 11 will be referred to as the "diode α," the diode D3 of the second arm 12 as the "diode β," and the diode D3 of the third arm 13 as the "diode γ."

[0030] In the first arm 11, the drain of the first semiconductor switch S1 (switch A) is connected to the first input terminal 61 of the power supply 6, and the source is connected to the cathode of the diode D3 (diode α). The anode of the first regenerative diode D1 is connected to the source of the first semiconductor switch S1 (switch A), and the cathode is connected to the drain of the first semiconductor switch S1 (switch A).

[0031] In the first arm 11, the drain of the second semiconductor switch S2 (switch D) is connected to the anode of the diode D3 (diode α), and the source is connected to the second input terminal 62 of the power supply 6. The second regenerative diode D2 has an anode connected to the source of the second semiconductor switch S2 (switch D) and a cathode connected to the drain of the second semiconductor switch S2 (switch D).

[0032] In the first arm 11, one end of a first coil L1 (coil A) is connected to a connection point between the first semiconductor switch S1 (switch A) and the diode D3 (diode α). The other end of the first coil L1 (coil A) is connected to a neutral point N1. In addition, in the first arm 11, one end of a fourth coil L4 (coil D) is connected to a connection point between the second semiconductor switch S2 (switch D) and the diode D3 (diode α). The other end of the fourth coil L4 (coil D) is connected to the neutral point N1.

[0033] In the second arm 12, the drain of the first semiconductor switch S1 (switch E) is connected to the first input terminal 61 of the power supply 6, and the source is connected to the cathode of the diode D3 (diode β). The anode of the first regenerative diode D1 is connected to the source of the first semiconductor switch S1 (switch E), and the cathode is connected to the drain of the first semiconductor switch S1 (switch E).

[0034] In the second arm 12, the drain of the second semiconductor switch S2 (switch B) is connected to the anode of the diode D3 (diode β), and the source is connected to the second input terminal 62 of the power supply 6. The second regenerative diode D2 has an anode connected to the source of the second semiconductor switch S2 (switch B) and a cathode connected to the drain of the second semiconductor switch S2 (switch B).

[0035] In the second arm 12, one end of a fifth coil L5 (coil E) is connected to a connection point between the first semiconductor switch S1 (switch E) and the diode D3 (diode β). The other end of the fifth coil L5 (coil E) is connected to a neutral point N1. In addition, in the second arm 12, one end of a second coil L2 (coil B) is connected to a connection point between the second semiconductor switch S2 (switch B) and the diode D3 (diode β). The other end of the second coil L2 (coil B) is connected to the neutral point N1.

[0036] In the third arm 13, the drain of the first semiconductor switch S1 (switch C) is connected to the first input terminal 61 of the power supply 6, and the source is connected to the cathode of the diode D3 (diode γ). The anode of the first regenerative diode D1 is connected to the source of the first semiconductor switch S1 (switch C), and the cathode is connected to the drain of the first semiconductor switch S1 (switch C).

[0037] In the third arm 13, the drain of the second semiconductor switch S2 (switch F) is connected to the anode of the diode D3 (diode γ), and the source is connected to the second input terminal 62 of the power supply 6. The second regenerative diode D2 has an anode connected to the source of the second semiconductor switch S2 (switch F) and a cathode connected to the drain of the second semiconductor switch S2 (switch F).

[0038] In the third arm 13, one end of a third coil L3 (coil C) is connected to a connection point between the first semiconductor switch S1 (switch C) and the diode D3 (diode γ). The other end of the third coil L3 (coil C) is connected to a neutral point N1. In addition, in the third arm 13, one end of a sixth coil L6 (coil F) is connected to a connection point between the second semiconductor switch S2 (switch F) and the diode D3 (diode γ). The other end of the sixth coil L6 (coil F) is connected to the neutral point N1.

[0039] The control circuit 2 is configured by a circuit equipped with a processor and memory, such as a microcontroller. The control circuit 2 controls the first semiconductor switch S1 and the second semiconductor switch S2 of each of the three arms 10. Specifically, the control circuit 2 applies a pulsed drive signal to the gate of the first semiconductor switch S1 and the second semiconductor switch S2 of each arm 10, thereby individually switching on / off the first semiconductor switch S1 and the second semiconductor switch S2 of each arm 10.

[0040] In this embodiment, the control circuit 2 controls the first semiconductor switch S1 and the second semiconductor switch S2 of each of the three arms 10 so as to sequentially excite the six coils L0 at intervals of 60 electrical degrees. Specifically, the control circuit 2 controls the first semiconductor switch S1 and the second semiconductor switch S2 of each of the three arms 10 so as to sequentially repeat the following: excitation of coils A, B, and C, excitation of coils B, C, and D, excitation of coils C, D, and E, excitation of coils D, E, and F, excitation of coils E, F, and A, and excitation of coils F, A, and B.

[0041] Here, when transitioning from excitation of any one set (here, three) of coils L0 to excitation of the next set of coils L0, a surge voltage occurs in the coils L0 of the former set of coils L0 that are not excited in the latter set of coils L0. For example, when transitioning from excitation of coils A, B, and C to excitation of coils B, C, and D, switch A is turned off, so that current is no longer supplied to coil A from power supply 6, and a surge voltage occurs.

[0042] Therefore, the drive circuit 1 has a return path using a diode D3 to prevent a relatively high surge voltage from being applied to the first semiconductor switch S1 and the second semiconductor switch S2. In other words, the drive circuit 1 causes a current to flow through the return path, thereby consuming the energy stored in the coil L0, which is the source of the surge voltage.

[0043] Specifically, when the excitation transitions from coils A, B, and C to coils B, C, and D, current flows in the return path via diode α, consuming the energy stored in coil A. Also, when the excitation transitions from coils B, C, and D to coils C, D, and E, current flows in the return path via diode β, consuming the energy stored in coil B.

[0044] Furthermore, when the excitation transitions from coils C, D, and E to coils D, E, and F, current flows in the return path via diode γ, consuming the energy stored in coil C. Furthermore, when the excitation transitions from coils D, E, and F to coils E, F, and A, current flows in the return path via diode α, consuming the energy stored in coil D.

[0045] Furthermore, when the excitation transitions from coils E, F, and A to coils F, A, and B, current flows in the return path via diode β, consuming the energy stored in coil E. Furthermore, when the excitation transitions from coils F, A, and B to coils A, B, and C, current flows in the return path via diode γ, consuming the energy stored in coil F.

[0046] [2. Operation] The operation of the drive circuit 1 according to the embodiment will be described below with reference to Fig. 3 to Fig. 5. Fig. 3 to Fig. 5 are all circuit diagrams showing an example of the operation of the drive circuit 1 according to the embodiment. For ease of explanation, in Fig. 3 to Fig. 5, the descriptions of the first semiconductor switch S1 and the second semiconductor switch S2 have been changed to clearly show the on / off of the first semiconductor switch S1 and the second semiconductor switch S2.

[0047] 3 shows a state in which the control circuit 2 has sent drive signals to the gates of the switches A to F to turn on the switches A, B, and C and turn off the switches D, E, and F. In the state shown in FIG. 3, current flows in the order of the first input terminal 61 of the power supply 6, switch A, coil A, neutral point N1, coil B, switch B, and second input terminal 62 of the power supply 6 (see solid arrow A1). Current also flows in the order of the first input terminal 61 of the power supply 6, switch C, coil C, neutral point N1, coil B, switch B, and second input terminal 62 of the power supply 6 (see solid arrow A2). Therefore, when the switches A, B, and C are on, the coils A, B, and C are excited, and the rotor 5 rotates so that the coils A, B, and C are attracted to the first salient poles 42 on which they are respectively provided.

[0048] FIG. 4 shows the state shown in FIG. 3 in which the control circuit 2 sends a drive signal to the gate of switch A to switch switch A from on to off. That is, in the state shown in FIG. 4, switches B and C are on, and switches A, D, E, and F are off. In the state shown in FIG. 4, a return path is formed that passes through coil A, neutral point N1, coil B, switch B, the second regenerative diode D2 of switch D, diode α, and coil A in this order (see solid arrow A3). In addition, a return path is formed that passes through coil A, neutral point N1, coil D, diode α, and coil A in this order (see solid arrow A4). Therefore, in the state shown in FIG. 4, current flows through these return paths, dissipating the energy stored in coil A, which is the source of the surge voltage.

[0049] FIG. 5 shows a state in which, in the state shown in FIG. 4, the control circuit 2 has applied a drive signal to the gate of switch D to switch D from off to on. That is, in the state shown in FIG. 5, switches B, C, and D are on, and switches A, E, and F are off. In the state shown in FIG. 5, current flows in the order of the first input terminal 61 of the power supply 6, switch C, coil C, neutral point N1, coil B, switch B, and second input terminal 62 of the power supply 6 (see solid arrow A5). Also, current flows in the order of the first input terminal 61 of the power supply 6, switch C, coil C, neutral point N1, coil D, switch D, and second input terminal 62 of the power supply 6 (see solid arrow A6). Therefore, when switches B, C, and D are on, coils B, C, and D are excited, and the rotor 5 rotates so that the coils B, C, and D are attracted to the first salient poles 42 on which they are respectively provided.

[0050] 5, if the energy stored in coil A has not yet been consumed, a return path is formed that passes through coil A, neutral point N1, coil B, switch B, switch D, diode α, and coil A in this order (see dashed arrow A7). Also, a return path is formed that passes through coil A, neutral point N1, coil D, switch D, and the second input terminal 62 of the power supply 6 in this order (see dashed arrow A8). As current flows through these return paths, the energy stored in coil A, which is the source of the surge voltage, is consumed.

[0051] The control circuit 2 may transition to the next state after all the energy stored in coil L0, which is the source of the surge voltage, has been consumed, that is, after the current flowing in the return path has become zero, or may transition to the next state without waiting for the current flowing in the return path to become zero. For example, when the source of the surge voltage is coil A, the control circuit 2 may transition from the state shown in Figure 4 to the state shown in Figure 5 after the current flowing in coil A has become zero, or may transition from the state shown in Figure 4 to the state shown in Figure 5 before the current flowing in coil A has become zero.

[0052] Thereafter, the control circuit 2 controls the first semiconductor switch S1 and the second semiconductor switch S2 of each of the three arms 10 to sequentially repeat the following: excitation of coils C, D, E, coils D, E, F, coils E, F, A, coils F, A, B, and coils A, B, C. This causes the rotor 5 of the switched reluctance motor 3 to rotate, that is, the switched reluctance motor 3 is driven.

[0053] 3. Advantages The advantages of the drive circuit 1 according to the embodiment will be described below with a comparison with a drive circuit 1A of a comparative example shown in Fig. 6. Fig. 6 is a circuit diagram showing the configuration of the drive circuit 1A of the comparative example. The drive circuit 1A of the comparative example differs from the drive circuit 1 according to the embodiment in that it includes six arms 10A.

[0054] Specifically, each arm 10A includes one semiconductor switch S0 and one diode D0. That is, the drive circuit 1A of the comparative example includes six semiconductor switches S0 and six diodes D0, which is three more diodes D0 than the drive circuit 1 according to the embodiment.

[0055] As shown in Fig. 6, in a first arm 11A of the six arms 10A, one end of a first coil L1 (coil A) is connected to a connection point between a semiconductor switch S0 (switch A) and a diode D0. The other end of the first coil L1 (coil A) is connected to a neutral point N1. In a second arm 12A of the six arms 10A, one end of a second coil L2 (coil B) is connected to a connection point between a semiconductor switch S0 (switch B) and a diode D0. The other end of the second coil L2 (coil B) is connected to the neutral point N1.

[0056] In a third arm 13A of the six arms 10A, one end of a third coil L3 (coil C) is connected to a connection point between the semiconductor switch S0 (switch C) and the diode D0. The other end of the third coil L3 (coil C) is connected to a neutral point N1. In a fourth arm 14A of the six arms 10A, one end of a fourth coil L4 (coil D) is connected to a connection point between the semiconductor switch S0 (switch D) and the diode D0. The other end of the fourth coil L4 (coil D) is connected to the neutral point N1.

[0057] In addition, in a fifth arm 15A of the six arms 10A, one end of a fifth coil L5 (coil E) is connected to a connection point between the semiconductor switch S0 (switch E) and the diode D0. The other end of the fifth coil L5 (coil E) is connected to a neutral point N1. In a sixth arm 16A of the six arms 10A, one end of a sixth coil L6 (coil F) is connected to a connection point between the semiconductor switch S0 (switch F) and the diode D0. The other end of the sixth coil L6 (coil F) is connected to the neutral point N1.

[0058] In the drive circuit 1A of the comparative example, as in the drive circuit 1 according to the embodiment, the control circuit 2 controls the semiconductor switch S0 of each arm 10A to repeatedly excite coils A, B, and C, coils B, C, and D, coils C, D, and E, coils D, E, and F, coils E, F, and A, and coils F, A, and B. This causes the rotor 5 of the switched reluctance motor 3 to rotate, that is, the switched reluctance motor 3 is driven. Also, in the drive circuit 1A of the comparative example, in order to prevent a relatively high surge voltage from being applied to the semiconductor switch S0, a current is passed through the return path via the diode D0, thereby dissipating the energy accumulated in the coil L0, which is the source of the surge voltage.

[0059] 7A and 7B show a comparison of the torque waveform when the switched reluctance motor 3 is driven using the drive circuit 1 according to the embodiment and the torque waveform when the switched reluctance motor 3 is driven using the drive circuit 1A of the comparative example. Fig. 7A is a waveform diagram showing the torque of the switched reluctance motor 3 according to the embodiment in discontinuous conduction mode. Fig. 7B is a waveform diagram showing the torque of the switched reluctance motor 3 according to the embodiment in continuous conduction mode.

[0060] Here, the discontinuous conduction mode refers to an operation mode in which the frequency of the current flowing through the coil L0 is relatively low and the current flows intermittently through the coil L0, while the continuous conduction mode refers to an operation mode in which the frequency of the current flowing through the coil L0 is relatively high and the current flows continuously through the coil L0.

[0061] In each of Figures 7A and 7B, the vertical axis represents torque (unit: N m), and the horizontal axis represents time (unit: seconds). In Figures 7A and 7B, the solid line represents the torque waveform when the drive circuit 1 according to the embodiment is used, and the dashed line represents the torque waveform when the drive circuit 1A of the comparative example is used. In Figure 7A, where the solid line and dashed line overlap, only the solid line is shown. In Figure 7B, the solid line and dashed line overlap throughout, so only the solid line is shown.

[0062] 7A and 7B, the torque waveforms are generally the same regardless of whether the drive circuit 1 or 1A is used. In other words, with regard to the torque of the switched reluctance motor 3, the performance of the drive circuit 1 according to the embodiment is equal to or better than the performance of the drive circuit 1A of the comparative example.

[0063] 8A and 8B show a comparison result between the waveform of the current flowing through the coil L0 when the switched reluctance motor 3 is driven using the drive circuit 1 according to the embodiment and the waveform of the current flowing through the coil L0 when the switched reluctance motor 3 is driven using the drive circuit 1A of the comparative example. Fig. 8A is a waveform diagram showing the current flowing through one of the coils L0 of the switched reluctance motor 3 according to the embodiment in discontinuous conduction mode. Fig. 8B is a waveform diagram showing the current flowing through one of the coils L0 of the switched reluctance motor 3 according to the embodiment in continuous conduction mode.

[0064] 8A and 8B both show the waveform of the current flowing through the first coil L1 (coil A), but the waveforms of the currents flowing through the other coils L0 are similar, just with different phases. In each of FIGS. 8A and 8B, the vertical axis represents current (unit: "A") and the horizontal axis represents time (unit: "seconds"). In each of FIGS. 8A and 8B, the solid line represents the current waveform when the drive circuit 1 according to the embodiment is used, and the dashed line represents the current waveform when the drive circuit 1A of the comparative example is used. In FIG. 8A, where the solid and dashed lines overlap, only the solid line is shown. In FIG. 8B, the solid and dashed lines overlap throughout, so only the solid line is shown.

[0065] 8A and 8B, the current waveforms are generally the same regardless of whether the drive circuit 1 or 1A is used. In other words, with regard to the current flowing through the coil L0 of the switched reluctance motor 3, the performance of the drive circuit 1 according to the embodiment is equal to or better than the performance of the drive circuit 1A of the comparative example.

[0066] As described above, the drive circuit 1 according to the embodiment can exhibit performance equivalent to or superior to that of the drive circuit 1A of the comparative example, despite having a smaller number of diodes D3 in each arm 10 than that of the drive circuit 1A of the comparative example. Therefore, the drive circuit 1 according to the embodiment has the advantage of being able to reduce manufacturing costs while maintaining the drive performance of the switched reluctance motor 3.

[0067] [4. Modifications] While the drive circuit, motor system, and switched reluctance motor of the present invention have been described above based on the embodiments, the present invention is not limited to these embodiments. As long as they do not deviate from the gist of the present invention, various modifications that would occur to those skilled in the art to the present embodiments and other forms constructed by combining some of the components of the embodiments are also included within the scope of the present invention.

[0068] In the embodiment, the multiple coils L0 in the switched reluctance motor 3 are connected to each other at the neutral point N1, but this is not limiting. For example, as shown in Fig. 9, in the switched reluctance motor 3, the multiple coils L0 may be connected to each other so as to form a closed loop. Fig. 9 is a circuit diagram showing a drive circuit 1 according to an embodiment and another example of a switched reluctance motor 3 according to an embodiment. In the example shown in Fig. 9, the multiple coils L0 are connected to each other in a hexagonal shape (in other words, the multiple coils L0 are configured in a hexagonal wiring configuration).

[0069] Specifically, the winding start of the first coil L1 (coil A) is connected to the winding end of the second coil L2 (coil B), and the winding start of the second coil L2 (coil B) is connected to the winding end of the third coil L3 (coil C). The winding start of the third coil L3 (coil C) is connected to the winding end of the fourth coil L4 (coil D), and the winding start of the fourth coil L4 (coil D) is connected to the winding end of the fifth coil L5 (coil E). The winding start of the fifth coil L5 (coil E) is connected to the winding end of the sixth coil L6 (coil F), and the winding start of the sixth coil L6 (coil F) is connected to the winding end of the first coil L1 (coil A).

[0070] As described above, connecting multiple coils L0 to each other to form a closed loop has the following advantages. Specifically, providing a neutral point N1 requires space in the switched reluctance motor 3 to provide a portion where one end of each coil L0 is connected together, whereas the above connection has the advantage that such space is not required. Also, providing a neutral point N1 allows current to flow through each coil L0 only in one direction, whereas the above connection allows current to flow in both directions in each coil L0, which has the advantage of providing a high degree of freedom in the current.

[0071] Incidentally, a switched reluctance motor 3 configured as described above in which multiple coils L0 are connected to form a closed loop can be used with a comparative driving circuit 1A, for example, as shown in FIG. 10. FIG. 10 is a circuit diagram showing the comparative driving circuit 1A and another example of a switched reluctance motor 3 according to an embodiment. In other words, the switched reluctance motor 3 can be used with various driving circuits as long as it is configured as follows. That is, the switched reluctance motor 3 includes a stator 4 and a rotor 5. The stator 4 has multiple pairs of first salient poles 42 to which multiple coils L0 are respectively attached. The rotor 5 has multiple second salient poles 52, and rotates when current is passed through each of the multiple coils L0 to excite them. The multiple coils L0 are connected to each other to form a closed loop.

[0072] In the embodiment, the switched reluctance motor 3 has six pairs (12 poles) of first salient poles 42 and ten second salient poles 52, but this is not limited to this. For example, the switched reluctance motor 3 may have three pairs (six poles) of first salient poles 42 and five second salient poles 52. In other words, the drive circuit 1 can be suitably used in a switched reluctance motor 3 where the number of pairs of first salient poles 42 is an integer multiple of six and the number of second salient poles 52 is an integer multiple of five.

[0073] The drive circuit 1 according to the embodiment can be suitably used for the switched reluctance motor 3 according to the embodiment, but is not limited to this. That is, the type of switched reluctance motor 3 that can be driven by the drive circuit 1 according to the embodiment is not particularly limited, and the drive circuit 1 can be applied to various switched reluctance motors 3.

[0074] [5. Summary] As described above, the drive circuit 1 according to the embodiment includes three arms 10 connected in parallel to the first input terminal 61 and the second input terminal 62 of the power supply 6. Each of the three arms 10 is configured as a series circuit of a first semiconductor switch S1, a second semiconductor switch S2, and a diode D3. The first semiconductor switch S1 is connected to the first input terminal 61 and has a first regenerative diode. The second semiconductor switch S2 is connected to the second input terminal 62 and has a second regenerative diode. The diode D3 is connected between the first semiconductor switch S1 and the second semiconductor switch S2. A plurality of coils L0 of the stator 4 of the switched reluctance motor 3 can be connected to each of the three arms 10. The drive circuit 1 rotates the rotor 5 of the switched reluctance motor 3 by passing a current through each of the plurality of coils L0 to excite them.

[0075] Such a drive circuit 1 has the advantage that the number of diodes D3 required to provide a return path can be reduced, thereby reducing manufacturing costs while maintaining the drive performance of the switched reluctance motor 3.

[0076] Also, for example, in the drive circuit 1, there are six coils L0. In a first arm 11 of the three arms 10, a first coil L1 of the multiple coils L0 is connected between a first semiconductor switch S1 and a diode D3, and a fourth coil L4 of the multiple coils L0 is connected between a second semiconductor switch S2 and a diode D3. In a second arm 12 of the three arms 10, a fifth coil L5 of the multiple coils L0 is connected between the first semiconductor switch S1 and a diode D3, and a second coil L2 of the multiple coils L0 is connected between the second semiconductor switch S2 and a diode D3. In a third arm 13 of the three arms 10, a third coil L3 of the multiple coils L0 is connected between the first semiconductor switch S1 and a diode D3, and a sixth coil L6 of the multiple coils L0 is connected between the second semiconductor switch S2 and a diode D3.

[0077] Such a drive circuit 1 has the advantage that the drive performance of the six-phase switched reluctance motor 3 can be maintained while reducing manufacturing costs.

[0078] Also, for example, in the drive circuit 1, the multiple coils L0 are connected to each other at the neutral point N1.

[0079] Such a drive circuit 1 has the advantage that the number of elements in the drive circuit 1 can be easily reduced compared to when a plurality of coils L0 are connected without providing a neutral point N1.

[0080] Also, for example, in the drive circuit 1, the multiple coils L0 are connected to each other so as to form a closed loop.

[0081] Such a drive circuit 1 has the advantage that, compared to connecting one end of each of multiple coils L0 to the neutral point N1, no space is required to set up the neutral point N1, and the degree of freedom in the current flowing through each coil L0 is improved.

[0082] Moreover, for example, the drive circuit 1 further includes a control circuit 2 that controls the first semiconductor switch S1 and the second semiconductor switch S2 of each of the three arms 10. The control circuit 2 controls the first semiconductor switch S1 and the second semiconductor switch S2 of each of the three arms 10 so as to sequentially excite the six coils L0 at intervals of an electrical angle of 60 degrees.

[0083] Such a drive circuit 1 has the advantage that it is easy to rotate the rotor 5 smoothly relative to the stator 4, and torque loss is unlikely to occur.

[0084] Also, for example, in the drive circuit 1, the switched reluctance motor 3 includes a stator 4 having multiple pairs of first salient poles 42 to which multiple coils L0 are respectively attached, and a rotor 5 having multiple second salient poles 52. The number of the multiple pairs of first salient poles 42 is an integer multiple of six, and the number of the multiple second salient poles 52 is an integer multiple of five.

[0085] Such a drive circuit 1 has the advantage that the switched reluctance motor 3 is less likely to be braked, and the switched reluctance motor 3 can be easily rotated smoothly.

[0086] Moreover, for example, the motor system 100 includes the above-described drive circuit 1 and a switched reluctance motor 3 that is driven by the drive circuit 1 that receives power from a power supply 6.

[0087] Such a motor system 100 has the advantage that the number of diodes D3 required to provide a return path can be reduced, thereby reducing manufacturing costs while maintaining the driving performance of the switched reluctance motor 3.

[0088] Furthermore, for example, the switched reluctance motor 3 is driven by the above-mentioned drive circuit 1 that receives power from a power supply 6.

[0089] Also, for example, a switched reluctance motor 3 includes a stator 4 and a rotor 5. The stator 4 has multiple pairs of first salient poles 42 to which multiple coils L0 are respectively attached. The rotor 5 has multiple second salient poles 52, and rotates when current is passed through each of the multiple coils L0 to excite them. The multiple coils L0 are connected to each other to form a closed loop.

[0090] Such a switched reluctance motor 3 has the advantages that, compared to a case in which one end of each of a plurality of coils L0 is connected to the neutral point N1, no space is required to provide the neutral point N1, and the degree of freedom in the current flowing through each coil L0 is improved. [Industrial Applicability]

[0091] The present invention can be used as a circuit for driving a switched reluctance motor mounted on equipment, such as a traction motor for an electric vehicle. [Explanation of symbols]

[0092] 100 Motor System 1. Drive circuit 10 Arm 11 First Arm 12 Second Arm 13 Third Arm S1 First semiconductor switch D1 First regenerative diode S2 Second semiconductor switch D2 Second regenerative diode D3 diode 1A Comparative example drive circuit 10A Arm 11A First Arm 12A Second Arm 13A Third Arm 14A 4th Arm 15A 5th Arm 16A 6th Arm S0 Semiconductor switch D0 diode 2. Control circuit 3 Switched Reluctance Motor 4 Stator 41 Main Unit 42 1st salient pole L0 coil L1 First coil L2 Second coil L3 Third coil L4 4th coil L5 5th coil L6 6th coil N1 Neutral point 5 rotor 51 Main unit 52 Second salient pole 53 Drive shaft 6 Power supply 61 First input terminal 62 Second input terminal A1~A8 arrows

Claims

1. three arms connected in parallel to the first input terminal and the second input terminal of the power supply; Each of the three arms comprises: a first semiconductor switch connected to the first input end and having a first regenerative diode; a second semiconductor switch connected to the second input end and having a second regenerative diode; a diode connected between the first semiconductor switch and the second semiconductor switch, a plurality of phase coils of a stator of a switched reluctance motor can be connected to each of the three arms, and a rotor of the switched reluctance motor is rotated by passing a current through each of the plurality of phase coils to excite them; The coils of the plurality of phases are configured as six phases, In a first arm of the three arms, one end of a first-phase coil among the plurality of phase coils is connected between the first semiconductor switch and the diode, and one end of a fourth-phase coil among the plurality of phase coils is connected between the second semiconductor switch and the diode, In a second arm of the three arms, one end of a fifth-phase coil among the plurality of phase coils is connected between the first semiconductor switch and the diode, and one end of a second-phase coil among the plurality of phase coils is connected between the second semiconductor switch and the diode, In a third arm of the three arms, one end of a third-phase coil among the plurality of phase coils is connected between the first semiconductor switch and the diode, and one end of a sixth-phase coil among the plurality of phase coils is connected between the second semiconductor switch and the diode, the other ends of the coils of the plurality of phases are connected to each other at a neutral point. Drive circuit.

2. A power supply includes three arms connected in parallel to a first input terminal and a second input terminal of the power supply, Each of the three arms has: a first semiconductor switch connected to the first input end and having a first regenerative diode; a second semiconductor switch connected to the second input end and having a second regenerative diode; a diode connected between the first semiconductor switch and the second semiconductor switch, a plurality of phase coils of a stator of a switched reluctance motor can be connected to each of the three arms, and a rotor of the switched reluctance motor is rotated by passing a current through each of the plurality of phase coils to excite them; The coils of the plurality of phases are configured as six phases, In a first arm of the three arms, one end of a first-phase coil among the plurality of phase coils is connected between the first semiconductor switch and the diode, and one end of a fourth-phase coil among the plurality of phase coils is connected between the second semiconductor switch and the diode, In a second arm of the three arms, one end of a fifth-phase coil among the plurality of phase coils is connected between the first semiconductor switch and the diode, and one end of a second-phase coil among the plurality of phase coils is connected between the second semiconductor switch and the diode, In a third arm of the three arms, one end of a third-phase coil among the plurality of phase coils is connected between the first semiconductor switch and the diode, and one end of a sixth-phase coil among the plurality of phase coils is connected between the second semiconductor switch and the diode, the coils of the plurality of phases are connected in series to one another in a circular shape to form a closed loop, and the other end of each of the coils of the plurality of phases is connected to the one end of a coil of another phase adjacent to the coil of that phase; Drive circuit.

3. a control circuit that controls the first semiconductor switch and the second semiconductor switch of each of the three arms; the control circuit controls the first semiconductor switch and the second semiconductor switch of each of the three arms so as to sequentially excite the coils of the plurality of phases at intervals of an electrical angle of 60 degrees.

3. The drive circuit according to claim 1 or 2.

4. The switched reluctance motor is a plurality of pairs of first salient poles provided in the stator, to which the coils of the plurality of phases are respectively attached; a plurality of second salient poles of the rotor; the number of the plurality of pairs of first salient poles is an integer multiple of 6, the number of the plurality of second salient poles is an integer multiple of 5; The drive circuit according to any one of claims 1 to 3.

5. A drive circuit according to any one of claims 1 to 4; the switched reluctance motor driven by the drive circuit supplied with power from the power supply, Motor system.

6. The driving circuit is driven by the driving circuit according to any one of claims 1 to 5, which receives power from the power supply. Switched reluctance motor.

Images