Claims:WE CLAIM:
1. A circuit (10) comprising:
a positive node (20) electrically coupled to a positive end (30) of one of a battery (40) or of a power supply (40);
a negative node (50) electrically coupled to a negative end (60) of one of the battery (40) or of the power supply (40);
a first convertor leg (70) electrically coupled between the positive node (20) and the negative node (50), wherein the first convertor leg (70) comprises:
a first high side switch (80) comprising a first high side switching element (90) and a first high side integrated body diode (100), wherein the first high side switch (80) is electrically coupled between the positive node (20) and a first node (110);
a first low side switch (120) comprising a first low side switching element (130) and a first low side integrated body diode (140), wherein the first low side switch (120) is electrically coupled between the negative node (60) and a second node (150);
a first phase (160) electrically coupled between the first node (120) and the second node (150),
wherein, the first high side switch (80), the first low side switch (120), and the first phase (160) are electrically coupled to each other in series in the first connector leg (70);
a second convertor leg (170) electrically coupled in parallel to the first convertor leg (70) between the positive node (20) and the negative node (50), wherein the second convertor leg (170) comprises:
a second high side switch (180) comprising a second high side switching element (190) and a second high side integrated body diode (200), wherein the second high side switch (180) is electrically coupled between the positive node (20) and a third node (210);
a second low side switch (220) comprising a second high side switching element (230) and a second low side integrated body diode (240), wherein the second low side switch (220) is electrically coupled between the negative node (50) and a fourth node (250);
a second phase (260) electrically coupled between the third node (210) and the fourth node (250),
wherein, the second high side switch (180), the second low side switch (220), and the second phase (260) are electrically coupled to each other in series in the second convertor leg (170);
a third phase (270) electrically coupled between the first node (110) of the first converter leg (70) and the fourth node (250) of the second converter leg (170);
a fourth phase (280) electrically coupled between the second node (150) of the first converter leg (70) and the third node (210) of the second converter leg (170),
wherein, the first convertor leg (70), the second converter leg (170), the third phase (270) and the fourth phase (280) are configured to drive a four-phase switched reluctance machine;
a first diode (290), wherein an anode (300) of the first diode (290) is electrically coupled between the first phase (160) and the first low side switch (120) and a cathode (310) of the first diode (290) is electrically coupled to the positive node (20);
a second diode (320), wherein an anode (330) of the second diode (320) is electrically coupled to the negative node (50) and a cathode (340) of the second diode (320) is electrically coupled between the first phase (160) and the first high side switch (80);
a third diode (350), wherein an anode (360) of the third diode (350) is electrically coupled between the second phase (260) and the second low side switch (220) and a cathode (370) of the third diode (350) is electrically coupled the positive node (20); and
a fourth diode (380), wherein an anode (390) of the fourth diode (380) is electrically coupled to the negative node (50) and a cathode (400) of the fourth diode (380) is electrically coupled between the second phase (260) and the second high side switch (180),
wherein the first phase (160), the second phase (260), the third phase (270) and the fourth phase (280) comprises one or more inductors, wherein the one or more inductors are coupled to each other in at least one of a series combination and a parallel combination,
wherein the first high side switching element (90), the first low side switching element (130), the second high side switching element (190) and the second low side switching element (230) comprises at least one of a transistor, a metal oxide semiconductor field effect transistor (MOSFET) and an insulated gate bipolar transistor (IGBT) with an integrated body diode for a device.
2. A method (410) for driving a four phase switched reluctance machine comprising:
magnetising a first phase and a third phase upon closing a first high side switch, a first low side switch and a second low side switch for driving the switched reluctance machine in a first time interval; (420)
magnetising the second phase and a third phase upon closing the first high side switch, a second high side switch and the second low side switch and simultaneously opening the first low side switch for driving the switched reluctance machine in a second time interval; (430)
magnetising the second phase and a fourth phase upon closing the first low side switch, the second high side switch and the second low side switch and simultaneously opening the first high side switch for driving the switched reluctance machine in a third time interval; and (440)
magnetising the first phase and the fourth phase upon closing the first high side switch, the first low side switch and the second high side switch and simultaneously opening the second low side switch for driving the switched reluctance machine in a fourth time interval, (450)
wherein, transition from the fourth time interval to the first time interval comprises closing the second low side switch and simultaneously opening the second high side switch. (460)
3. The method (410) as claimed in claim 2, further comprising demagnetizing the first phase through a freewheeling path along the first high side switch and a first diode upon closing the first high side switch, the second high side switch and the second low side switch and simultaneously opening the first low side switch.
4. The method (410) as claimed in claim 2, further comprising demagnetizing the third phase through a freewheeling path along the second low side switch and a second diode upon closing the first low side switch, the second high side switch and the second low side switch and simultaneously opening the first high side switch.
5. The method (410) as claimed in claim 2, further comprising demagnetizing the second phase through a freewheeling path along the second high side switch and a third diode upon closing the first high side switch, the first low side switch and the second high side switch and simultaneously opening the second low side switch.
6. The method (410) as claimed in claim 2, further comprising demagnetizing the fourth phase through a freewheeling path along the first high side switch and a first diode by closing the first high side switch, the first low side switch and the second low side switch.
7. The method (410) as claimed in claim 2, further comprising demagnetizing at least one of the first inductor, the second inductor, the third inductor or the fourth inductor by driving the electrical power stored in the at least one of the first inductor, the second inductor, the third inductor, the fourth inductor or a combination thereof to one of a battery or a power supply upon opening at least three of the first high side switch, the first low side switch, the second high side or the second low side switch simultaneously.

, Description:BACKGROUND
[0001] Embodiments of the present disclosure relate to a circuit for driving a switched reluctance machine, and more particularly to a circuit and a method for driving a four-phase switched reluctance machine.
[0002] A switched reluctance machine works on the principle of reluctance torque. Further, a driver circuit is used to drive the switched reluctance machine in a predefined sequence. Based on the requirement, different driver circuits are used to drive the switched reluctance machines in different phase configuration such as three-phase, four-phase or the like to perform a desired function.
[0003] One type of driver circuit used to drive a four-phase switched reluctance machine includes four inductors electrically coupled to eight switches and eight diodes respectively in the driver circuit. Further, each of a pair of switches of the eight switches is turned on to enable a first inductor to drive the driver circuit in a first phase. Further, a next pair of switches gets turned on to enable a second inductor to drive the driver circuit in a second phase. The process repeats with a third inductor and a fourth inductor to drive the switched reluctance machine in third and four phases. Moreover, in such a circuit, the connectivity between the four inductors, eight switches and the eight diodes become challenging, hence making the driver circuit complex. Further, such complexity of the driver circuit increases hardware of the circuit and also power consumption by a plurality of components in the driver circuit increases.
[0004] Another type of driver circuit used to drive a four-phase switched reluctance machine includes an H-bridge circuit for each of the four phases. Further, each of the H-bridge circuit includes four switches to enable each of the corresponding four phases. Moreover, the total switches in the driver circuit add up to sixteen, which increases hardware of the driver circuit and hence increases the power consumption of the driver circuit.
[0005] Hence there is a need of an improved circuit and a method for driving a four-phase switched reluctance machine to address the aforementioned issues.
BRIEF DESCRIPTION
[0006] In accordance with one embodiment of the disclosure, a circuit to drive a four-phase switched reluctance machine is provided. The circuit includes a positive node electrically coupled to a positive end of one of a battery or a power supply. The circuit also includes a negative node electrically coupled to a negative end of one of the battery or the power supply. The circuit also includes a first convertor leg electrically coupled between the positive node and the negative node. The first convertor leg includes a first high side switch. The first high side switch includes a first high side switching element and a first high side integrated body diode. The first high side switch is electrically coupled between the positive node and a first node. The first convertor leg also includes a first low side switch. The first low side switch includes a first low side switching element and a first low side integrated body diode. The first low side switch is electrically coupled between the negative node and a second node. The first convertor leg also includes a first phase electrically coupled between the first node and the second node. The first high side switch, the first low side switch, and the first phase are electrically coupled to each other in series in the first connector leg. The circuit also includes a second convertor leg electrically coupled in parallel to the first convertor leg between the positive node and the negative node. The second convertor leg includes a second high side switch. The second high side switch includes a second high side switching element and a second high side integrated body diode. The second high side switch is electrically coupled between the positive node and a third node. The second convertor leg also includes a second low side switch. The second low side switch includes a second low side switching element and a second low side integrated body diode. The second low side switch is electrically coupled between the negative node and a fourth node. The second connector leg also includes a second phase electrically coupled between the third node and the fourth node. The second high side switch, the second low side switch, and the second phase are electrically coupled to each other in series in the second convertor leg. The circuit also includes a third phase electrically coupled between the first node in the first converter leg and the fourth node in the second converter leg. The circuit also includes a fourth phase electrically coupled between the second node in the first converter leg and the third node in the second converter leg. The first convertor leg, the second converter leg, third phase and the fourth phase are configured to drive a four-phase switched reluctance machine. The circuit also includes a first diode. An anode of the first diode is electrically coupled between the first phase and the first low side switch and a cathode of the first diode is electrically coupled the positive node. The circuit also includes a second diode. An anode of the second diode is electrically coupled to the negative node and a cathode of the second diode is electrically coupled between the first phase and the first high side switch. The circuit also includes a third diode. An anode of the third diode is electrically coupled between the second phase and the second low side switch and a cathode of the third diode is electrically coupled to the positive node. The circuit also includes a fourth diode. An anode of the fourth diode is electrically coupled to the negative node and a cathode of the fourth diode is electrically coupled between the second phase and the second high side switch. The first phase, the second phase, the third phase and the fourth phase include one or more inductors, wherein the one or more inductors are coupled to each other in at least one of a series combination and a parallel combination. Also, the first high side switching element, the first low side switching element, the second high side switching element and the second low side switching element includes at least one of a transistor, a metal oxide semiconductor field effect transistor (MOSFET) and an insulated gate bipolar transistor (IGBT) with an integrated body diode.
[0007] In accordance with another embodiment of the disclosure, a method for driving a four-phase switched reluctance machine is included. The method includes magnetising a first inductor and a third inductor upon closing a first high side switch, a first low side switch and a second low side switch for driving the switched reluctance machine in a first time interval. The method also includes magnetising the second inductor and a third inductor upon closing the first high side switch, a second high side switch and the second low side switch and simultaneously opening the first low side switch for driving the switched reluctance machine in a second time interval. The method also includes magnetising the second inductor and a fourth inductor upon closing the first low side switch, the second high side switch and the second low side switch and simultaneously opening the first high side switch for driving the switched reluctance machine in a third time interval. The method also includes magnetising the first inductor and the fourth inductor upon closing the first high side switch, the first low side switch and the second high side switch and simultaneously opening the second low side switch for driving the switched reluctance machine in a fourth time interval. Transition from the fourth time interval to the first time interval comprises closing the second low side switch and simultaneously opening the second high side switch.
[0008] To further clarify the advantages and features of the present disclosure, a more particular description of the disclosure will follow by reference to specific embodiments thereof, which are illustrated in the appended figures. It is to be appreciated that these figures depict only typical embodiments of the disclosure and are therefore not to be considered limiting in scope. The disclosure will be described and explained with additional specificity and detail with the appended figures.
BRIEF DESCRIPTION OF THE DRAWINGS
The disclosure will be described and explained with additional specificity and detail with the accompanying figures in which:
[0009] FIG. 1 is a circuit to drive a four-phase switched reluctance machine in accordance with an embodiment of the present disclosure; and
[0010] FIG. 2 is a flow chart representing steps involved in a method for driving a four-phase switched reluctance machine in accordance with an embodiment of the present disclosure.
[0011] Further, those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and may not have necessarily been drawn to scale. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the figures with details that will be readily apparent to those skilled in the art having the benefit of the description herein.
DETAILED DESCRIPTION
[0012] For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Such alterations and further modifications in the illustrated system, and such further applications of the principles of the disclosure as would normally occur to those skilled in the art are to be construed as being within the scope of the present disclosure.
[0013] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Similarly, one or more devices or sub-systems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other devices, sub-systems, elements, structures, components, additional devices, additional sub-systems, additional elements, additional structures or additional components. Appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.
[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.
[0015] In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.
[0016] Embodiments of the present disclosure relate to a circuit and a method for driving a four-phase switched reluctance machine. The circuit includes a positive node electrically coupled to a positive end of one of a battery or a power supply. The circuit also includes a negative node electrically coupled to a negative end of one of the battery or the power supply. The circuit also includes a first convertor leg electrically coupled between the positive node and the negative node. The first convertor leg includes a first high side switch. The first high side switch includes a first high side switching element and a first high side integrated body diode. The first high side switch is electrically coupled between the positive node and a first node. The first convertor leg also includes a first low side switch. The first low side switch includes a first low side switching element and a first low side integrated body diode. The first low side switch is electrically coupled between the negative node and a second node. The first convertor leg also includes a first phase electrically coupled between the first node and the second node. The first high side switch, the first low side switch, and the first phase are electrically coupled to each other in series in the first connector leg. The circuit also includes a second convertor leg electrically coupled in parallel to the first convertor leg between the positive node and the negative node. The second convertor leg includes a second high side switch. The second high side switch includes a second high side switching element and a second high side integrated body diode. The second high side switch is electrically coupled between the positive node and a third node. The second convertor leg also includes a second low side switch. The second low side switch includes a second low side switching element and a second low side integrated body diode. The second low side switch is electrically coupled between the negative node and a fourth node. The second connector leg also includes a second phase electrically coupled between the third node and the fourth node. The second high side switch, the second low side switch, and the second phase are electrically coupled to each other in series in the second convertor leg. The circuit also includes a third phase electrically coupled between the first node in the first converter leg and the fourth node in the second converter leg. The circuit also includes a fourth phase electrically coupled between the second node in the first converter leg and the third node in the second converter leg. The first convertor leg, the second converter leg, third phase and the fourth phase are configured to drive a four-phase switched reluctance machine. The circuit also includes a first diode. An anode of the first diode is electrically coupled between the first phase and the first low side switch and a cathode of the first diode is electrically coupled the positive node. The circuit also includes a second diode. An anode of the second diode is electrically coupled to the negative node and a cathode of the second diode is electrically coupled between the first phase and the first high side switch. The circuit also includes a third diode. An anode of the third diode is electrically coupled between the second phase and the second low side switch and a cathode of the third diode is electrically coupled the positive node. The circuit also includes a fourth diode. An anode of the fourth diode is electrically coupled to the negative node and a cathode of the fourth diode is electrically coupled between the second phase and the second high side switch. The first phase, the second phase, the third phase and the fourth phase include one or more inductors, wherein the one or more inductors are coupled to each other in at least one of a series combination and a parallel combination. Also, the first high side switching element, the first low side switching element, the second high side switching element and the second low side switching element includes at least one of a transistor, a metal oxide semiconductor field effect transistor (MOSFET) and an insulated gate bipolar transistor (IGBT) with an integrated body diode.
[0017] FIG. 1 is a circuit (10) to drive a four-phase switched reluctance machine in accordance with an embodiment of the present disclosure. As used herein, the switched reluctance machine (SRM) or a switched reluctance motor is a type of a stepper motor which works on reluctance torque. Power in the SRM is delivered to a plurality of windings in a stator rather than a plurality of windings in a rotor of the SRM.
[0018] The embodiment of the present disclosure represents a circuit (10) configured to operate a multi-phase SRM, more specifically to operate the four-phase switched reluctance machine (SRM). The circuit (10) is connected to a controller to monitor an operation of the four-phase SRM.
[0019] The circuit (10) includes a positive node (20) electrically coupled to a positive end (30) of one of a battery (40) or a power supply (40). The circuit (10) also includes a negative node (50) electrically coupled to a negative end (60) of one of the battery (40) or the power supply (40). As used herein, the energy storage device (40) is defined as a type of device used to store electrical energy, and releasing the stored electrical energy when needed.
[0020] In one embodiment, the battery (40) may be an accumulator, or a similar direct current (DC) source. One of the battery (40) or the power supply (40) may be configured to supply electrical power between the positive node (20) and the negative node (50).
[0021] The circuit (10) also includes a first convertor leg (70) electrically coupled between the positive node (20) and the negative node (50). The first convertor leg (70) includes a first high side switch (80). The first high side switch (80) includes a first high side switching element (90). The first high side switch (80) is also integrated with a first high side integrated body diode (100). The first high side switching element (90) along with the first high side integrated body diode (100) are electrically coupled between the positive node (20) and a first node (110). In one embodiment, a first end (not shown) of the first high side switch (80) may be electrically coupled to the positive node (20). Further, a second end (not shown) of the first high side switch (80) may correspond to the first node (110). As used herein, switch is an electronic device configured to interrupt flow of the electrical energy within the circuit either being completely closed or being completely open.
[0022] Furthermore, the first convertor leg (70) also includes a first low side switch (120). The first low side switch (120) includes a first low side switching element (130). The first low side switch (120) is also integrated with a first low side integrated body diode (140). The first low side switch (120) along with the first low side integrated body diode (140) are electrically coupled between the negative node (50) and a second node (150). In one embodiment, a first end (not shown) of the first low side switch (120) may correspond to the second node (150). Also, a second end (not shown) of the first low side switch (120) may be electrically coupled to the negative node (50).
[0023] The first connector leg (70) also includes a first phase (160) electrically coupled between the first node (110) and the second node (150). The first phase (160) includes one or more first inductors which are electrically coupled to each other in at least one of a series combination and a parallel combination. In one specific embodiment, the first phase (160) may include a first inductor electrically coupled between the first node (110) and the second node (150).
[0024] Moreover, the first high side switch (80), the first low side switch (120), and the first phase (160) are all electrically coupled to each other in series in the first connector leg (70).
[0025] The circuit (10) also includes a second connector leg (170) electrically coupled in parallel to the first convertor leg (70) between the positive node (20) and the negative node (50). The second connector leg (170) includes a second high side switch (180). The second high side switch (180) includes a second high side switching element (190). The second high side switch (180) is also integrated with a second high side integrated body diode (200). The second high side switch (180) along with the second high side integrated body diode (200) are electrically coupled between the positive node (20) and a third node (210). In one embodiment, a first end (not shown) of the second high side switch (180) may be electrically coupled to the positive node (20). Further, a second end (not shown) of the second high side switch (180) may correspond to the third node (210).
[0026] Furthermore, the second convertor leg (170) includes a second low side switch (220). The second low side switch (220) includes a second low side switching element (230). The second low side switch (220) is also integrated with a second low side integrated body diode (240). The second low side switch (210) along with the second low side integrated body diode (220) is electrically coupled between the negative node (50) and a fourth node (250). In one embodiment, a first end (not shown) of the second low side switch (220) may correspond to the forth node (250). Also, a second end (not shown) of the second low side switch (220) may be electrically coupled to the negative node (50).
[0027] The second connector leg (170) also includes a second phase (260) electrically coupled between the third node (210) and the fourth node (250). The second phase (260) includes one or more second inductors which are electrically coupled to each other in at least one of the series combination and the parallel combination. In one specific embodiment, the second phase (260) may include a second inductor electrically coupled between the third node (210) and the fourth node (250).
[0028] Moreover, the second high side switch (180), the second low side switch (220), and the second phase (260) are electrically coupled to each other in series in the second convertor leg (170).
[0029] In one exemplary embodiment, the first high side integrated body diode (100), the first low side integrated body diode (140), the second high side integrated body diode (200) and the second low side integrated body diode (240) may include a Zener diode respectively.
[0030] Furthermore, the first high side switching element (90), the first low side switching element (130), the second high side switching element (190) and the second low side switching element (230) includes at least one of a transistor, a metal oxide semiconductor field effect transistor (MOSFET) and an insulated gate bipolar transistor (IGBT) respectively with an integrated body diode. In one embodiment, the first high side switch (80), the first low side switch (120), the second high side switch (180) and the second low side switch (220) may correspond to a unidirectional gating switch.
[0031] In addition, the circuit (20) includes a third phase (270) electrically coupled between the first node (110) of the first converter leg (70) and the fourth node (250) of the second converter leg (170). The third phase (270) includes one or more third inductors which are electrically coupled to each other in at least one of the series combination and the parallel combination. In one specific embodiment, the third phase (270) may include a third inductor electrically coupled between the first node (110) and the fourth node (250) of the first convertor leg (70) and the second convertor leg (170) respectively.
[0032] The circuit (10) also includes a fourth phase (280) electrically coupled between the second node (150) of the first converter leg (70) and the third node (210) of the second converter leg (170). The fourth phase (280) includes one or more fourth inductors which are electrically coupled to each other in at least one of the series combination and the parallel combination. In one specific embodiment, the fourth phase (280) may include a fourth inductor electrically coupled between the second node (150) and the third node (210) of the first convertor leg (70) and the second convertor leg (170) respectively.
[0033] Furthermore, the first convertor leg (70), the second converter leg (170), the third phase (270) and the fourth phase (280) are configured to drive the four-phase switched reluctance machine.
[0034] The circuit (10) also includes a first diode (290). Further, an anode (300) of the first diode (290) is electrically coupled between the first phase (160) and the first low side switch (120) and a cathode (310) of the first diode (290) is electrically coupled to the positive node (20).
[0035] The circuit (10) also include a second diode (320). Further, an anode (330) of the second diode (320) is electrically coupled to the negative node (50) and a cathode (340) of the second diode (320) is electrically coupled between the first phase (160) and the first high side switch (80).
[0036] Furthermore, the circuit (10) includes a third diode (350). An anode (360) of the third diode (350) is electrically coupled between the second phase (260) and the second low side switch (220) and a cathode (370) of the third diode (350) is electrically coupled the positive node (20).
[0037] The circuit (10) also includes a fourth diode (380). Also, an anode (390) of the fourth diode (380) is electrically coupled to the negative node (50) and a cathode (400) of the fourth diode (380) is electrically coupled between the second phase (210) and the second high side switch (180).
[0038] In one exemplary embodiment, the first diode (290), the second diode (320), the third diode (350) and the fourth diode (380) may be a power diode. As used herein, the diode is an electronic device which maintains the flow of electrical energy in one direction.
[0039] In operation, the electrical energy from the positive end (30) of the energy storing device (40) is transmitted to the positive node (20) of the circuit. The electrical energy is then passed through the first phase (160) and the third phase (270) through the first node (110) of the first connector leg (70), upon closing the first high side switch (80), the first low side switch (120) and the second low side switch (220). Henceforth, enabling the circuit (10) to operate in a first time interval through the first phase (160) and the third phase (270). An output of the circuit (10) at the first time interval is measured across the first end of the second high side switch (180) and the second end of the second low side switch (220). More specifically, upon closing the first high side switch (80), the first low side switch (120) and the second low side switch (220), the electrical energy from the energy storing device (40) is applied across the first phase (160) and the third phase (270). Also, due to the first low side switch (120) and the second low side switch (220) being closed, current through the first phase (160) and third phase (270) increases rapidly, thereby enabling the circuit (10) to operate in the first time interval.
[0040] Furthermore, the electrical energy is passed within the circuit in order to close the first high side switch (80), the second high side switch (180) and the second low side switch (220), and simultaneously opening the first low side switch (120). Consequently, the first phase (160) is demagnetised through a freewheeling path along the first high side switch (80) and the first diode (290). Thereby, enabling the circuit (10) to operate in a second time interval through the second phase (260) and the third phase (270). Further, the output of the second time interval is measured across the first end of the second high side switch (180) and the second end of the second low side switch (220).
[0041] More specifically, upon closing the first high side switch (80), the second high side switch (180) and the second low side switch (220), the electrical energy is applied across the second phase (260) and the third phase (270). Also, due to the second high side switch (180) and the second low side switch (220) being closed, the current through the second phase (260) and the third phase (270) increases rapidly. Furthermore, the current through the first phase (160) is freewheeled through a local loop formed along the first high side switch (80) and the first diode (290) in order to demagnetise the first phase (160).
[0042] As used herein, the term “demagnetization” is defined as removing magnetic energy from a device, wherein the magnetic energy is a vector field which expresses a density of permanent or an induced magnetic dipole of a magnetic material. In one exemplary embodiment, the magnetic material may correspond to the one or more inductors of the first phase (160), the second phase (260), the third phase (270) and the fourth phase (280) respectively. Further, the freewheeling path is defined as a path created for a magnetised device to discharge energy due to generation of back electromotive force.
[0043] Furthermore, the electrical energy is now made to pass through the second phase (260) and the fourth phase (280), upon closing the first low side switch (120), the second high side switch (180) and the second low side switch (220) and simultaneously opening the first high side switch (80). Consequently, the second phase (270) is demagnetised through the freewheeling path along the second high side switch (180) and the third diode (350). Thereby, enabling the circuit (10) to operate in a third time interval through the second phase (260) and the fourth phase (280). Further, the output of the third time interval is measured across the first end of the second high side switch (180) and the second end of the second low side switch (220).
[0044] More specifically, upon closing the first low side switch (120), the second high side switch (180) and the second low side switch (220), the electrical energy is applied across the second phase (260) and the fourth phase (280). Also, due to the second high side switch (180), the current through the second phase (260) and the fourth phase (280) increases rapidly. Furthermore, the current through the third phase (270) freewheels through the local loop formed along the second high side switch (180) and the third diode (350).
[0045] In addition, the electrical energy is further made to pass through the first phase (160) and the fourth phase (280), upon closing the first high side switch (80), the first low side switch (120) and the second high side switch (180) and simultaneously opening the second low side switch (210). Consequently, the fourth phase (260) is demagnetised through the freewheeling path along the first high side switch (100) and a first diode (270) by closing the first high side switch (100), the first low side switch (120) and the second low side switch (220). Thereby enabling the circuit (10) to operate in a fourth time interval. Further, the output of the fourth time interval is measured across the first end of the second high side switch (180) and the second end of the second low side switch (220).
[0046] More specifically, upon closing the first high side switch (80), the first low side switch (120) and the second high side switch (180), the electrical energy is applied across the first phase (160) and the fourth phase (280). Also, due to the second high side switch (180) and the second low side switch (220) being closed, the current through the first phase (160) and the fourth phase (280) increases rapidly. Furthermore, the current through the second phase (260) freewheels through the local loop formed along the first high side switch (80) and the first diode (290).
[0047] Also, transition from the fourth time interval to the first time interval is enabled by closing the second low side switch (220) and simultaneously opening the second high side switch (180). Henceforth, keeping the operation of the circuit (10) continuous at all four time intervals. In addition, at least one of the first phase (160), the second phase (260), the third phase (270) and the fourth phase (280) is demagnetised by opening at least three of the first high side switch (80), the first low side switch (120), the second high side switch (180) and the second low side switch (220) to simultaneously drive the electrical power stored in at least one of the first phase (160), the second phase (260), the third phase (270) and the fourth phase (280) to one of the battery (40) or the power supply (40).
[0048] Furthermore, the current through the fourth phase (280) flows along the first diode (290), the positive node (20), the negative node (50) and the first phase (160) of the circuit (10). In such a condition, the circuit (10) is subjected to a negative voltage through the first diode (290). Moreover, the electrical energy trapped in the circuit (10) is fed to one of the battery (40) or the power supply (40). In addition, the current through the fourth phase (280) drops down due to the negative voltage generated within the circuit (10).
[0049] FIG. 2 is a flow chart representing steps involved in a method for driving a four-phase switched reluctance machine in accordance with an embodiment of the present disclosure. The method (410) includes magnetising a first phase and a third phase upon closing a first high side switch, a first low side switch and a second low side switch for driving the switched reluctance machine in a first time interval in step 420.
[0050] The method (410) also includes magnetising the second phase and a third phase upon closing the first high side switch, a second high side switch and the second low side switch and simultaneously opening the first low side switch for driving the switched reluctance machine in a second time interval in step 430. In one embodiment, driving the switched reluctance machine in the second time interval may include demagnetizing the first phase through a freewheeling path. The freewheeling path may be along the first high side switch and a first diode upon closing the first high side switch, the second high side switch and the second low side switch and simultaneously opening the first low side switch.
[0051] Furthermore, the method (410) includes magnetising the second phase and a fourth phase upon closing the first low side switch, the second high side switch and the second low side switch and simultaneously opening the first high side switch for driving the switched reluctance machine in a third time interval in step 440. In one embodiment, driving the switched reluctance machine in the third time interval may include demagnetizing the third phase through a freewheeling path. The freewheeling path may be along the second low side switch and a second diode upon closing the first low side switch, the second high side switch and the second low side switch and simultaneously opening the first high side switch.
[0052] The method (410) also includes magnetising the first phase and the fourth phase upon closing the first high side switch, the first low side switch and the second high side switch and simultaneously opening the second low side switch for driving the switched reluctance machine in a fourth time interval in step 450. In one embodiment, driving the switched reluctance machine in the fourth time interval may include demagnetizing the second phase through a freewheeling path. The freewheeling path may be along the second high side switch and a third diode upon closing the first high side switch, the first low side switch and the second high side switch and simultaneously opening the second low side switch
[0053] In addition, the method (410) for transition from the fourth time interval to the first time interval includes closing the second low side switch and simultaneously opening the second high side switch in step 460. In one embodiment, the method for transition from the fourth time interval to the first time interval may include demagnetizing the fourth phase through a freewheeling path. The freewheeling path may be along the first high side switch and a first diode by closing the first high side switch, the first low side switch and the second low side switch.
[0054] In one further embodiment, the method (410) may further include demagnetizing at least one of the first phase, the second phase, the third phase or the fourth phase by opening at least three of the first high side switch, the first low side switch, the second high side or the second low side switch and simultaneously driving the electrical power stored in at least one of the first phase, the second phase the third phase and the fourth phase to one of a battery or a power supply.
[0055] Various embodiments of the circuit and a method for driving a four-phase switched reluctance machine due to the usage of four inductors, four switches and the four diodes, the hardware and hence the complexity of the circuit is reduced. Furthermore, due to the reduction in hardware, the power consumption by the plurality of components of the circuit is reduced.
[0056] In addition, an overlap between the four phases is maximised duo which the circuit generates higher net torque and low sides torque ripple. Also, the four-phase SRM circuit provides appropriate drive control for four quadrant operations of the SRM.
[0057] Furthermore, the configurational logic of the circuit supports functionality requirement of each phase of the SRM and that of phase independence due to the usage of minimal number of switches.
[0058] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.
[0059] The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, order of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts need to be necessarily performed. Also, those acts that are not dependant on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples.