Switched reluctance motor device, and driving circuit and reluctance motor thereof

A switched reluctance motor device includes first and second winding components wound around a stator one on top of the other, multiple damping capacitors, a capacitor battery unit and a switching circuit. The first winding component has multiple first winding portions coupled in series to form a close loop. The second winding component has multiple second winding portions coupled in a star configuration and cooperating with the damping capacitors to form multiple resonant circuits. The switching circuit switches one first winding portion from a magnetizing state to a demagnetizing state, and induces generation of a resonant current in the corresponding resonant circuit to charge the capacitor battery unit.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Taiwanese Application No. 103121931, filed on Jun. 25, 2014.

FIELD OF THE INVENTION

The invention relates to a reluctance motor device, and more particularly to a switched reluctance motor device.

BACKGROUND OF THE INVENTION

Referring toFIGS. 1 and 2, a conventional switched reluctance motor device includes a reluctance motor1and a driving circuit2. The reluctance motor1includes a stator11having eight projecting poles (A, A′, B, B′, C, C′, D, D′) , a rotor12disposed within the stator11and having six salient poles (a, a′, b, b′, c, c′), and four phase windings that are respectively wound around radially opposite pairs of the projecting poles (A-A′, B-B′, C-C′, D-D′) of the stator11(hereinafter, phase windings (A″, B″, C″, D″) are used). Each of the phase windings (A″, B″, C″, D″) has a first winding segment (L1) and a second winding segment (L2) respectively wound around the projecting poles of the corresponding radially opposite pair.

The driving circuit2is electrically coupled to a direct current (DC) power source (Vdc), and includes four bridge arms21-24electrically coupled in parallel with the DC power source (Vdc), and respectively corresponding to the phase windings (A″, B″, C″, D″). Each of the bridge arms21-24includes a first switch (Qu) electrically coupled between a positive terminal of the DC power source (Vdc) and a first end of a corresponding phase winding (A″, B″, C″, D″), a second switch (Qn) electrically coupled between a negative terminal of the DC power source (Vdc) and a second end of the corresponding phase winding (A″, B″, C″, D″), a first diode (D1) having an anode that is electrically coupled to the negative terminal of the DC power source (Vdc) and a cathode that is electrically coupled to the first end of corresponding phase winding (A″, B″, C″, D″), and a second diode (D2) having an anode that is electrically coupled to the second end of corresponding phase winding (A″, B″, C″, D″)and a cathode that is electrically coupled to the positive terminal of the DC power source (Vdc).

The driving circuit2sequentially switches the phase windings (A″, B″, C″ and D″) to a magnetizing state. Referring toFIGS. 1 to 3, as an example, in a first basic cycle, the first and second switches (Qu,Qn) of the bridge arm21that correspond to the phase winding (A″) conduct, such that the first and second winding segments (L1, L2) of the phase winding (A″) are electrically coupled to the DC power source (Vdc), and the corresponding projecting poles (A, A′) generate magnetic attractions that cause movements of the salient poles (a, a′) toward the projecting poles (A, A′). Then, in a second basic cycle, the first and second switches (Qu, Qn) of the bridge arm21becomes non-conducting, and the first and second switches (Qu, Qn) of the bridge arm22conduct, such that the first and second winding segments (L1, L2) of the phase winding (B″) are electrically coupled to the DC power source (Vdc), and the corresponding projecting poles (B, B′) generate magnetic attractions that cause movements of the salient poles (a, a′) toward the projecting poles (B, B′). Similarly, the phase windings (C″, D″) are subsequently and sequentially switched to the magnetizing state, to thereby drive clockwise rotation of the rotor12. In contrast, when the phase windings (A″, B″, C″, D″) are switched to the magnetizing state in a sequence of (D″), (C″), (B″), and (A″), the rotation of the rotor12may be driven in a counterclockwise direction.

However, referring toFIG. 4, at the end of each basic cycle, e.g., when the first and second switches (Qu, Qn) of the bridge arm21are switched to non-conducting, a transient counter-electromotive force (e1, e2) may be generated on each of the first and second winding segments (L1, L2) of the phase winding (A″), resulting in a large current flowing toward the DC power source (Vdc) through the first and second diodes (D1, D2) of the bridge arm21, and in a high-voltage impact on the DC power source (Vdc), which may cause over-heating of the DC power source (Vdc) due to an excessively large transient current.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a switched reluctance motor device that may recycle a counter-electromotive force generated by windings thereof.

According to one aspect of the present invention, a switched reluctance motor device includes a rotor, a stator, a first winding component, a second winding component, a capacitor battery unit, a switching circuit and N damping capacitors, where N is an integer not smaller than 3.

The first winding component has a number N of first phase winding portions that are wound around the stator, and that are electrically coupled in series to form a close loop having N first circuit nodes among the first phase winding portions. The second winding component has N second phase winding portions that are wound around the stator, that respectively correspond to the first phase winding portions, and that are electrically coupled in a star configuration. For each corresponding pair of the first phase winding portions and the second phase winding portions, one of the first phase winding portion and the second phase winding portion is wound around the other of the first phase winding portion and the second phase winding portion.

The capacitor battery unit is electrically coupled to the second winding component, and is configured to provide a direct current (DC) voltage.

The switching circuit is electrically coupled to the capacitor battery unit and the N first circuit nodes for transmitting the DC voltage from the capacitor battery unit to the first winding component, and is configured to switch one of the first phase winding portions, which serves as an operating phase winding portion, from a magnetizing state to a demagnetizing state.

The N damping capacitors respectively and electrically coupled to the second phase winding portions in parallel, to thereby form N resonant circuits that respectively correspond to the N first phase winding portions and that are electrically coupled to the capacitor battery unit.

To put the operating phase winding portion in the magnetizing state, the switching circuit makes conduction between the operating phase winding portion and the capacitor battery unit, resulting in magnetization of the operating phase winding portion by the DC voltage provided from the capacitor battery unit, and enabling rotation of the rotor.

To put the operating phase winding portion in the demagnetizing state, the switching circuit terminates conduction between the operating phase winding portion and the capacitor battery unit, resulting in demagnetization of the operating phase winding portion, such that one of the resonant circuits that corresponds to the operating phase winding portion makes resonance, and generates a resonant current to charge the capacitor battery unit.

Another object of the present invention is to provide a driving circuit of the switched reluctance motor device of this invention.

According to another aspect of the present invention, a driving circuit for driving a reluctance motor is provided. The reluctance motor includes a rotor, a stator, a first winding component and a second winding component. The first winding component has a number N of first phase winding portions that are wound around the stator, and that are electrically coupled in series to form a close loop having N first circuit nodes among the first phase winding portions, where N is an integer not smaller than 3. The second winding component has N second phase winding portions that are wound around the stator, that respectively correspond to the first phase winding portions, and that are electrically coupled in a star configuration. For each corresponding pair of the first phase winding portions and the second phase winding portions, one of the first phase winding portion and the second phase winding portion is wound around the other one of the first phase winding portion and the second phase winding portion.

The driving circuit includes a capacitor battery unit, a switching circuit and N damping capacitors.

The capacitor battery unit has a positive terminal and a negative terminal to provide a direct current (DC) voltage therebetween.

The switching circuit includes N bridge arms and N damping capacitors. The N bridge arms are electrically coupled in parallel between a positive terminal and a negative terminal of the capacitor battery unit. Each of the bridge arms includes a first switch and a second switch that are electrically coupled in series between the positive and negative terminals of the capacitor battery unit. A common node of the first and second switches is to be electrically coupled to a respective one of the first circuit nodes. The N damping capacitors are electrically coupled to the capacitor battery unit, and to be respectively and electrically coupled to the second phase winding portions in parallel.

Yet another object of the present invention is to provide a reluctance motor of the switched reluctance motor device of this invention.

According to another aspect of the present invention, a reluctance motor includes a rotor, a stator, a first winding component and a second winding component.

The first winding component has a number N of first phase winding portions that are wound around the stator, and that are electrically coupled in series to form a close loop having N first circuit nodes among the first phase winding portions, where N is an integer not smaller than 3.

The second winding component has N second phase winding portions that are wound around the stator, that respectively correspond to the first phase winding portions, and that are electrically coupled in a star configuration.

For each corresponding pair of the first phase winding portions and the second phase winding portions, one of the first phase winding portion and the second phase winding portion is wound around the other one of the first phase winding portion and the second phase winding portion.

DETAILED DESCRIPTION OF THE EMBODIMENT

Referring toFIGS. 5 to 7, the embodiment of the switched reluctance motor device according to this invention is shown to include a reluctance motor3and a driving circuit4.

The reluctance motor3includes a stator31and a rotor32disposed within the stator31. In this embodiment, the switched reluctance motor device is a three-phase switched reluctance motor device, and the stator31has six projecting poles (X, X′, Y, Y′, Z, Z′) that are evenly arranged. The reluctance motor3further includes a first winding component33and a second winding component34partially wound around the projecting poles (X, X′, Y, Y′, Z, Z′). In this embodiment, for each of the projecting poles (X, X′, Y, Y′, Z, Z′), the first winding component33is disposed at an inner side in contrast to the second winding component34.

Referring toFIG. 6, the first winding component33has three first phase winding portions (U1, V1, W1) electrically coupled in series to form a Δ-configuration close loop with three first circuit nodes (R, S, T) among the first phase winding portions (U1, V1, W1), and the second winding component34has three second phase winding portions (U2, V2, W2) electrically coupled in a Y-configuration (i.e., a star-configuration) with a common node (N) thereamong and three second circuit nodes (U, V, W) respectively corresponding to the second phase winding portions (U2, V2, W2), and respectively corresponding to the first phase winding portions (U1, V1, W1).

Each of the first and second phase winding portions (U1, V1, W1, U2, V2, W2) has two windings (u1, v1, w1, u2, v2, w2) , as shown inFIG. 5. The first phase winding portions (U1, V1, W1) respectively correspond to radially opposite pairs of the projecting poles (X-X′, Y-Y′, Z-Z′) with the two windings (u1or v1or w1) of each first phase winding portion (U1or V1or W1) respectively wound around the projecting poles (X, X′ or Y, Y′ or Z, Z′) of the corresponding radially opposite pair. Likewise, the second phase winding portions (U2, V2, W2) respectively correspond to the radially opposite pairs of the projecting poles (X-X′, Y-Y′, Z-Z′) with the two windings (u2or v2or w2) of each second phase winding portion (U2or V2or W2) respectively wound around the projecting poles (X, X′ or Y, Y′ or Z, Z′) of the corresponding radially opposite pair on top of the two windings (u1or v1or w1) of the respective first phase winding portion (U1or V1or W1). As such, the windings (ul, u2) of the phase winding portions (U1, U2) are coaxially wound around the radially opposite projecting poles (X, X′), the windings (v1, v2) of the phase winding portions (V1, V2) are coaxially wound around the radially opposite projecting poles (Y, Y′) , and the windings (w1, w2) of the phase winding portions (W1, W2) are coaxially wound around the radially opposite projecting poles (Z, Z′). The rotor32of this embodiment has four evenly arranged salient poles (x, x′, y, y′). In one embodiment, the first phase winding portions (U1, V1, W1) of the first winding component33and the second phase winding portions (U2, V2, W2) of the second winding component34have the same number of turns.

Referring toFIG. 7, the driving circuit4of this embodiment is electrically coupled to the reluctance motor3via the circuit nodes (R, S, T, U, V, W) for driving the reluctance motor3, and includes a capacitor battery unit41, a switching circuit that has three bridge arms42,43,44electrically coupled in parallel between positive and negative terminals of the capacitor battery unit41, and a three-phase bridge rectifier circuit45. The capacitor battery unit41is configured to provide a direct current (DC) voltage (Vdc) between the positive and negative terminals thereof to serve as a power source for driving the reluctance motor3, is characterized in large current throughput, and may store 50 ampere-hour electric charges in this embodiment.

Each of the bridge arms42,43,44has a first switch (U+, V+, W+) and a second switch (U−, V−, W−) electrically coupled in series between the positive and negative terminals of the capacitor battery unit41. A common node of each pair of the first switch (U+, V+, W+) and the second switch (U−, V−, W−) is electrically coupled to a respective one of the first circuit nodes (R, S, T). Each of the bridge arms42,43,44further has a first free-wheeling diode (D+) electrically coupled to the first switch (U+, V+, W+) in parallel and having an anode that is electrically coupled to the respective one of the first circuit nodes (R, S, T), and a second free-wheeling diode (D−) electrically coupled to the second switch (U−, V−, W−) in parallel and having a cathode that is electrically coupled to the respective one of the first circuit nodes (R, S, T). In this embodiment, each of the first and second switches (U+, V+, W+, U−, V−, W−) is a power transistor.

Referring toFIG. 6, the switched reluctance motor device of this embodiment further includes three damping capacitors (Cd) respectively and electrically coupled to the second phase winding portions (U2, V2, W2) in parallel, to thereby form three resonant circuits35,36,37, respectively. In one embodiment, each of the damping capacitors (Cd) is a non-polar capacitor having an operating frequency that ranges between 300 Hz and 1000 Hz. In one embodiment, a switching frequency of the driving circuit4may be associated with a resonant frequency of the resonant circuits35,36,37. That is, the switching frequency maybe determined according to the second phase winding portion (U2, V2, W2) and the damping capacitor (Cd) of the resonant circuit35,36,37, and may be equal or close to the resonant frequency of the resonant circuit35,36,37. In other words, the switching frequency of the driving circuit4maybe determined as being capable of inducing resonance of the resonant circuits35,36,37. In one embodiment, the switching frequency is about 400 Hz. In application, the damping capacitors (Cd) may be incorporated into either the reluctance motor3or the driving circuit4.

The three-phase bridge rectifier circuit45is electrically coupled to the resonant circuits35,36,37, and includes three diode circuits (rectifier arms)46,47,48electrically coupled in parallel between the positive and negative terminals of the capacitor battery unit41. Each of the diode circuits46,47,48includes a first diode (Du+, Dv−, Dw+) and a second diode (Du−, Dv−, Dw−) electrically coupled in series, and has a forward direction from the negative terminal of the capacitor battery unit41to the positive terminal of the capacitor battery unit41. A common node of the first diode (Du+, Dv+, Dw+) and the second diode (Du−, Dv−, Dw−) of each of the diode circuits46,47,48is electrically coupled to a respective one of the second circuit nodes (U, V, W) of the second winding component34.

In this embodiment, the driving circuit4is a switched controller that operates in a manner of phase-separated magnetization (magnetic shunt), and that sequentially switches the first phase winding portions (U1, V1, W1) of the first winding component33to a magnetizing state, in which the first phase winding portion (U1, V1or W1) magnetizes the projecting poles (X, X′ or Y, Y′ or Z, Z′) of the corresponding radially opposite pair due to a current flowing therethrough. That is, the driving circuit4is configured to make a conduction path between two bridge arms. As an example, the first switch (U+) (first operating switch) of the bridge arm42and the second switch (V−) (second operating switch) of the bridge arm43conduct, to thereby electrically couple the first phase winding portion (U1) (operating phase winding portion) to the capacitor battery unit41, and switch the first phase winding portion (U1) to the magnetizing state using the DC voltage (Vdc) to convert the electric energy into magnetic energy. As a result, referring toFIG. 5, the projecting poles (X, X′) of the stator31generate magnetic attractions that cause movements of the salient poles (x, x′) of the rotor32toward the projecting poles (X, X′), respectively. Then, the switches (U+, V−) are switched to non-conducting (at this time, the first phase winding portion (U1) is switched to a demagnetizing state), and the first switch (V|) of the bridge arm43and the second switch (W−) of the bridge arm44are switched to conducting, to thereby electrically couple the first phase winding portion (V1) to the capacitor battery unit41, and switch the first phase winding portion (V1) to the magnetizing state using the DC voltage (Vdc) to result in magnetic attractions that cause movements of the salient poles (y, y′) of the rotor32toward the projecting poles (Y, Y′), respectively. Then, these two switches (V+, W−) are switched to non-conducting, and the first switch (W+) of the bridge arm44and the second switch (U−) of the bridge arm42are switched to conduct, to thereby switch the first phase winding portion (W1) to the magnetizing state. By repetition of the abovementioned steps, the rotor32may be driven to rotate in the counterclockwise direction. In contrast, when the driving circuit4switches the first phase winding portions (U1, V1, W1) to the magnetizing state in a sequence of (W1), (V1) and (U1), the rotor32may be driven to rotate in the clockwise direction.

Particularly, when the first phase winding portion that is in the magnetizing state, for example, the first phase winding portion (U1) that is coupled between the bridge arms42,43, is switched to the demagnetizing state from the magnetizing state by switching the switches (U+, V−) from conducting to non-conducting, the first phase winding portion (U1) may generate electric energy due to vanishing of the magnetic energy, i.e., generation of a counter-electromotive force may occur. At this time, since the switching frequency of the driving circuit4is equal or close to the resonant frequency of the resonant circuit35that corresponds in position to the first phase winding portion (U1), the resonant circuit35may sense energy provided by the counter-electromotive force to thereby induce resonance. Referring toFIGS. 8 and 9, a resonant current may be generated from the resonant circuit35to charge the capacitor battery unit41via the three-phase bridge rectifier circuit45. Note thatFIG. 9shows an equivalent circuit of the three-phase bridge rectifier circuit45, which operates as a full-wave rectifier circuit, to thereby illustrate current flow under this situation. When the resonant current is positive, and the damping capacitor (Cd) is charged by the resonant current to thereby have a voltage higher than that of the capacitor battery unit41, a discharge current of the damping capacitor (Cd) may flow through a current loop formed by the damping capacitor (Cd), the first diode (Dv+), the capacitor battery unit41, and the second diode (Du−), to thereby charge the capacitor battery unit41. When the resonant current is negative, and the damping capacitor (Cd) is charged by the resonant current to thereby have a voltage higher than that of the capacitor battery unit41, a discharge current of the damping capacitor (Cd) may flow through a current loop formed by the damping capacitor (Cd), the first diode (Du+), the capacitor battery unit41, and the second diode (Dv−), to thereby charge the capacitor battery unit41.

Similarly, when each of the first phase winding portions (V1, W1) is switched to the demagnetizing state from the magnetizing state, the corresponding resonant circuit36,37may induce resonance to generate the resonant current and charge the capacitor battery unit41via the three-phase bridge rectifier circuit45. Accordingly, the counter-electromotive force generated by the first phase winding portions (U1, V1, W1) maybe effectively reused to extend battery life of the capacitor battery unit41.

It should be noted that the concept of this invention should not be limited in the three-phase reluctance motor device, and may be applied to other multiple-phase reluctance motor devices. In application to an N-phase reluctance motor device (N is an integer not smaller than 3), the stator31may have N pairs of opposite projecting poles; the first winding component33may include N first phase winding portions electrically coupled in series, forming a close loop that has N first circuit nodes among the first phase winding portions, and respectively wound around the N pairs of opposite projecting poles; the second winding component34may include N second phase winding portions respectively wound around the N pairs of opposite projecting poles, and electrically coupled in a star configuration; the driving circuit4may include N aforesaid bridge arms; and the rectifier circuit45may include N aforesaid diode circuits.

In summary, the embodiment of the switched reluctance motor device according to the present invention includes the first phase winding portions (U1, V1, W1) coupled in the Δ-configuration, and the resonant circuits35,36,37formed by the second phase winding portions (U2, V2, W2) that are coupled in the Y-configuration and corresponding damping capacitors (Cd) that are respectively coupled to the second phase winding portions (U2, V2, W2) in parallel, such that when one of the first phase winding portions (U1, V1, W1) is switched from the magnetizing state to the demagnetizing state, the counter-electromotive force thus generated may induce resonance in the corresponding resonant circuit35,36,37, resulting in generation of the resonant current to charge the capacitor battery unit41via the three-phase bridge rectifier circuit45. In such a manner, the counter-electromotive forces generated by the first phase winding portions (U1, V1, W1) may be effectively reused to extend the battery life of the capacitor battery unit41.