JP7765838B2 - Drive circuit, motor system, and switched reluctance motor - Google Patents

Description

The present invention relates to a drive circuit for driving a switched reluctance motor, a motor system equipped with the drive circuit, and a switched reluctance motor used in the motor system.

Patent document 1 discloses a switched reluctance motor.

JP 2017-147778 A

The present invention aims to provide a drive circuit, motor system, and switched reluctance motor that can reduce manufacturing costs while maintaining the driving performance of the switched reluctance motor.

To achieve the above object, a drive circuit according to one embodiment of the present invention comprises 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 composed of 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 in the 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.

In addition, in order to achieve the above-mentioned object, a motor system according to one embodiment of the present invention comprises the drive circuit and the switched reluctance motor driven by the drive circuit supplied with power from the power source.

In order to achieve the above object, a switched reluctance motor according to one embodiment of the present invention comprises 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.

The present invention provides a drive circuit, motor system, and switched reluctance motor that can reduce manufacturing costs while maintaining the driving performance of the switched reluctance motor.

FIG. 1 is a circuit diagram showing the configuration of a motor system including a drive circuit according to an embodiment. FIG. 2 is a schematic diagram showing the configuration of a switched reluctance motor according to an embodiment of the present invention. FIG. 3 is a circuit diagram showing an example of the operation of the drive circuit according to the embodiment. FIG. 4 is a circuit diagram showing an example of the operation of the drive circuit according to the embodiment. FIG. 5 is a circuit diagram showing an example of the operation of the drive circuit according to the embodiment. FIG. 6 is a circuit diagram showing the configuration of a drive circuit of a comparative example. FIG. 7A is a waveform diagram showing torque of the switched reluctance motor according to the embodiment in discontinuous conduction mode. FIG. 7B is a waveform diagram showing torque of the switched reluctance motor according to the embodiment in the continuous conduction mode. 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. 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. 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. 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.

Embodiments of the present invention will be described in detail below with reference to the drawings. Note that each embodiment described below represents a specific example of the present invention. The numerical values, shapes, methods, components, component connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the present invention. Furthermore, in each figure, substantially identical components are designated by the same reference numerals, and duplicate explanations may be omitted or simplified.

[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.

[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.

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 this embodiment, the stator 4 has 12 poles, and therefore the number of first salient poles 42 is 12.

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

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. In this embodiment, a pair of first salient poles 42 facing 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 a pair of first salient poles 42 may be connected in series or in parallel.

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

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

In this embodiment, as shown in Figure 1, the multiple coils L0 are connected to each other at the neutral point N1. That is, one end of each of the first coil L1 (coil A), second coil L2 (coil B), third coil L3 (coil C), fourth coil L4 (coil D), fifth coil L5 (coil E), and sixth coil L6 (coil F) is connected to the same neutral point N1.

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, multiple second salient poles (teeth) 52, and a drive shaft 53. As described above, in this embodiment, the rotor 5 has 10 poles, so the number of second salient poles 52 is 10. In other words, the number of multiple second salient poles 52 is an integer multiple of 5.

The main body 51 is circular in plan view and is formed from a magnetic material such as non-oriented silicon steel plate.

The multiple 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 multiple second salient poles 52 are arranged at equal intervals around the circumferential direction of the main body 51.

The drive shaft 53 is a long rod-shaped member that passes through the center of the main body 51 in a plan view, runs along the thickness direction of the main body 51, and is formed integrally with the main body 51. The drive shaft 53 rotates in conjunction with the rotation of the rotor 5.

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, a second salient pole 52 located near one or more first salient poles 42, each equipped with one or more coils L0, is attracted to the first salient pole 42 so as to move to a position facing the first salient pole 42. As multiple coils L0 are subsequently excited in sequence by the drive circuit 1, 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.

[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.

The three arms 10 are connected in parallel to the first input terminal 61 and the second input terminal 62 of the power supply 6. In this embodiment, the power supply 6 is a DC power supply that 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.

Each of the three arms 10 is composed 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. 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.

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.

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 current through each of the plurality of coils L0 to excite them, thereby rotating the rotor 5 of the switched reluctance motor 3.

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." Furthermore, for ease of explanation, the first semiconductor switch S1 of the first arm 11 will be referred to as "switch A," the second semiconductor switch S2 of the first arm 11 as "switch D," the first semiconductor switch S1 of the second arm 12 as "switch B," the second semiconductor switch S2 as "switch E," the first semiconductor switch S1 of the third arm 13 as "switch C," and the second semiconductor switch S2 as "switch F." Furthermore, 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."

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).

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 anode of the second regenerative diode D2 is connected to the source of the second semiconductor switch S2 (switch D), and the cathode is connected to the drain of the second semiconductor switch S2 (switch D).

In the first arm 11, one end of the first coil L1 (coil A) is connected to the 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 the neutral point N1. Also, in the first arm 11, one end of the fourth coil L4 (coil D) is connected to the 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.

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).

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 anode of the second regenerative diode D2 is connected to the source of the second semiconductor switch S2 (switch B), and the cathode is connected to the drain of the second semiconductor switch S2 (switch B).

In the second arm 12, one end of the fifth coil L5 (coil E) is connected to the 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 the neutral point N1. Also, in the second arm 12, one end of the second coil L2 (coil B) is connected to the 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.

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).

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 anode of the second regenerative diode D2 is connected to the source of the second semiconductor switch S2 (switch F), and the cathode is connected to the drain of the second semiconductor switch S2 (switch F).

In the third arm 13, one end of the third coil L3 (coil C) is connected to the 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 the neutral point N1. Also, in the third arm 13, one end of the sixth coil L6 (coil F) is connected to the 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.

The control circuit 2 is composed of 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 individually switches the first semiconductor switch S1 and the second semiconductor switch S2 of each arm 10 on and off by applying a pulsed drive signal to the gates of the first semiconductor switch S1 and the second semiconductor switch S2 of each arm 10.

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 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 to sequentially repeat the following: excitation of coils A, B, C, excitation of coils B, C, D, excitation of coils C, D, E, excitation of coils D, E, F, excitation of coils E, F, A, and excitation of coils F, A, B.

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 is generated in the coils L0 of the former set that are not excited in the latter set. 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, preventing current from being supplied to coil A from the power supply 6, and generating a surge voltage.

Therefore, the drive circuit 1 has a return path using diode D3 to prevent the 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 current to flow through the return path, thereby dissipating the energy stored in coil L0, which is the source of the surge voltage.

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

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.

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

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

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

Figure 4 shows the state shown in Figure 3 when 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 Figure 4, switches B and C are on, and switches A, D, E, and F are off. In the state shown in Figure 4, a return path is formed that passes through coil A, neutral point N1, coil B, switch B, second regenerative diode D2 of switch D, diode α, and coil A in that 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 that order (see solid arrow A4). Therefore, in the state shown in Figure 4, current flows through these return paths, dissipating the energy stored in coil A, the source of the surge voltage.

Figure 5 shows the state shown in Figure 4 in which the control circuit 2 sends a drive signal to the gate of switch D to switch D from off to on. That is, in the state shown in Figure 5, switches B, C, and D are on, and switches A, E, and F are off. In the state shown in Figure 5, current flows in the following order: first input terminal 61 of power supply 6, switch C, coil C, neutral point N1, coil B, switch B, and second input terminal 62 of power supply 6 (see solid arrow A5). Current also flows in the following order: first input terminal 61 of power supply 6, switch C, coil C, neutral point N1, coil D, switch D, and second input terminal 62 of 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 coils B, C, and D are attracted to the first salient poles 42 on which they are respectively located.

In the state shown in Figure 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.

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, i.e., after the current flowing through the return path has reached zero, or it may transition to the next state without waiting for the current flowing through the return path to reach zero. For example, if 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 through coil A has reached zero, or it may transition from the state shown in Figure 4 to the state shown in Figure 5 before the current flowing through coil A has reached zero.

The control circuit 2 then 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, i.e., the switched reluctance motor 3 is driven.

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.

Specifically, each arm 10A has one semiconductor switch S0 and one diode D0. In other words, the comparative example drive circuit 1A has six semiconductor switches S0 and six diodes D0, which is three more diodes D0 than the drive circuit 1 according to the embodiment.

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

In addition, in the third arm 13A of the six arms 10A, one end of the third coil L3 (coil C) is connected to the 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 the neutral point N1. In the fourth arm 14A of the six arms 10A, one end of the fourth coil L4 (coil D) is connected to the 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.

In addition, in the fifth arm 15A of the six arms 10A, one end of the fifth coil L5 (coil E) is connected to the 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 the neutral point N1. In the sixth arm 16A of the six arms 10A, one end of the sixth coil L6 (coil F) is connected to the 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.

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, then coils B, C, and D, then coils C, D, and E, then coils D, E, and F, then coils E, F, and A, and then coils F, A, and B. This causes the rotor 5 of the switched reluctance motor 3 to rotate, thereby driving the switched reluctance motor 3. Furthermore, 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, current is passed through the return path via diode D0, thereby dissipating the energy stored in coil L0, which is the source of the surge voltage.

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

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

In each of Figures 7A and 7B, the vertical axis represents torque (units: Nm), and the horizontal axis represents time (units: seconds). Also, in Figures 7A and 7B, the solid line represents the torque waveform when using the drive circuit 1 according to the embodiment, and the dashed line represents the torque waveform when using the drive circuit 1A of the comparative example. Note that in Figure 7A, where the solid and dashed lines overlap, only the solid line is shown. Also, in Figure 7B, the solid and dashed lines overlap throughout, so only the solid line is shown.

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

Figures 8A and 8B show a comparison of the current waveform flowing through coil L0 when the switched reluctance motor 3 is driven using the drive circuit 1 according to the embodiment and the current waveform flowing through coil L0 when the switched reluctance motor 3 is driven using the drive circuit 1A of the comparative example. Figure 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. Figure 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.

Figures 8A and 8B both show the waveform of the current flowing through the first coil L1 (coil A), but the waveforms of the current flowing through the other coil L0 are similar, just with different phases. In each of Figures 8A and 8B, the vertical axis represents current (units: "A") and the horizontal axis represents time (units: "seconds"). Also, in each of Figures 8A and 8B, the solid line represents the current waveform when using the drive circuit 1 according to the embodiment, and the dashed line represents the current waveform when using the drive circuit 1A of the comparative example. Note that in Figure 8A, where the solid and dashed lines overlap, only the solid line is shown. Also, in Figure 8B, the solid and dashed lines overlap throughout, so only the solid line is shown.

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

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 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.

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.

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 limited to this. 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 the embodiment and another example of a switched reluctance motor 3 according to the 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).

Specifically, the beginning of the first coil L1 (coil A) is connected to the end of the second coil L2 (coil B), and the beginning of the second coil L2 (coil B) is connected to the end of the third coil L3 (coil C). Furthermore, the beginning of the third coil L3 (coil C) is connected to the end of the fourth coil L4 (coil D), and the beginning of the fourth coil L4 (coil D) is connected to the end of the fifth coil L5 (coil E). Furthermore, the beginning of the fifth coil L5 (coil E) is connected to the end of the sixth coil L6 (coil F), and the beginning of the sixth coil L6 (coil F) is connected to the end of the first coil L1 (coil A).

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 location where one end of each coil L0 is connected together, whereas the above connection has the advantage that such space is not required. Furthermore, providing a neutral point N1 means that current can only flow in one direction through each coil L0, whereas the above connection allows current to flow in both directions through each coil L0, providing another advantage of greater flexibility in the current.

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 drive circuit 1A, for example, as shown in FIG. 10. FIG. 10 is a circuit diagram showing the comparative drive 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 drive 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.

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 if 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.

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. In other words, 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 it can be applied to various switched reluctance motors 3.

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.

With such a drive circuit 1, the number of diodes D3 required to provide a return path can be reduced, which has the advantage of reducing manufacturing costs while maintaining the drive performance of the switched reluctance motor 3.

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

Such a drive circuit 1 has the advantage of being able to reduce manufacturing costs while maintaining the drive performance of the six-phase switched reluctance motor 3.

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

This type of drive circuit 1 has the advantage that it is easier to reduce the number of elements in the drive circuit 1 compared to when multiple coils L0 are connected without providing a neutral point N1.

Also, for example, in drive circuit 1, multiple coils L0 are connected to each other to form a closed loop.

With such a drive circuit 1, compared to connecting one end of each of multiple coils L0 to the neutral point N1, there is the advantage that 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.

Also, 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 60 electrical degrees.

This type of drive circuit 1 has the advantage that it makes it easier to rotate the rotor 5 smoothly relative to the stator 4, and torque loss is less likely to occur.

Furthermore, for example, in the drive circuit 1, the switched reluctance motor 3 has a stator 4 with multiple pairs of first salient poles 42 to which multiple coils L0 are respectively attached, and a rotor 5 with 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.

This type of drive circuit 1 has the advantage that the switched reluctance motor 3 is less likely to be braked, making it easier to rotate the switched reluctance motor 3 smoothly.

Furthermore, for example, the motor system 100 includes the above-mentioned drive circuit 1 and a switched reluctance motor 3 driven by the drive circuit 1 supplied with power from a power source 6.

With such a motor system 100, the number of diodes D3 required to provide a return path can be reduced, which has the advantage of reducing manufacturing costs while maintaining the driving performance of the switched reluctance motor 3.

Furthermore, for example, the switched reluctance motor 3 is driven by the above-mentioned drive circuit 1, which receives power from the power source 6.

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.

Such a switched reluctance motor 3 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.

The present invention can be used as a circuit to drive a switched reluctance motor installed in equipment, such as a traction motor in an electric vehicle.

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 Drive circuit of comparative example 10A Arm 11A First arm 12A Second arm 13A Third arm 14A Fourth arm 15A Fifth arm 16A Sixth arm S0 Semiconductor switch D0 Diode 2 Control circuit 3 Switched reluctance motor 4 Stator 41 Body 42 First salient pole L0 Coil L1 First coil L2 Second coil L3 Third coil L4 Fourth coil L5 Fifth coil L6 Sixth coil N1 Neutral point 5 Rotor 51 Body 52 Second salient pole 53 Drive shaft 6 Power supply 61 First input terminal 62 Second input terminal A1 to A8 Arrow

Claims (6)

three arms connected in parallel to the first input terminal and the 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 other ends of the coils of the plurality of phases are connected to each other at a neutral point.
Drive circuit. 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 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. 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 . 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 . 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. 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.