Patent Application
20170256354
Various embodiments relate generally to aircraft systems, and more particularly, to electronic motor control systems.
Aircraft electrical systems typically include one or more motor controllers to drive high power motors at various locations via long cables. To save vehicle weight, the cables used to deliver the high-power are unshielded. Since the cables are unshielded, however, an increased level of electromagnetic interference may be emitted.
To account for high current loads, motor controllers may implement a plurality of semiconductor switches connected in a parallel and a passive power filter to address EMI and Power Quality requirements. Standard semiconductor switches are typically available in discrete current ratings such as, for example, 100 amps (A), 200 A, 300 A, etc. These parallel switches, however, do not inherently share current equally. To compensate for the unequal current-sharing, the parallel switching arrangement used to drive the high-power motors are operated below rated current values. Additionally, the total power conversion efficiency provided by the unequal current-sharing parallel switching arrangement is lower than the ideal case for equal current-sharing switches.
According to a non-limiting embodiment, a parallel semiconductor switching system includes an input filter circuit, a plurality of switching circuits, and a current-sharing filter inductor. The switching circuits receive the filtered voltage signal (e.g., filter voltage) generated by the input filter circuit, and each switching circuit outputs a respective current signal (e.g., electrical current). The current-sharing filter inductor includes a plurality of windings. Each winding has a winding input and a winding output. The winding input of each winding is connected to a switching output of a respective switching circuit, and the winding output of each winding is connected to one another to form a common node. The common node is connected directly to a load such that the current-sharing filter inductor assists sharing of load current among plurality of switching circuits.
According to another non-limiting embodiment, a method of sharing current generated by a parallel semiconductor switching system to drive a load comprises generating at least one filtered voltage, delivering the filter voltage to a plurality of parallel switching circuits, and generating a plurality of individual current signals (e.g., individual electrical currents). The method further includes delivering each current to a respective winding and combining the winding currents at a common node to generate a combined current signal (e.g., a combined current). The method further includes outputting the combined current directly to a load so as to drive the load.
According to still another non-limiting embodiment, a filter inductor is configured to share current generated by a plurality of switching circuits included in a parallel semiconductor switching system. The filter inductor comprises a core element, a first winding, and a second winding. The first winding extends from a first proximate terminal end to an opposing first distal terminal end, and the second winding extends from a second proximate terminal end to an opposing second distal terminal end. The first and second windings are wrapped around the core element at an alternating sequential arrangement with respect to one another.
The subject matter which is regarded as the present disclosure is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the present disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
Traditional parallel topology high-power switching assemblies such as those illustrated in
Various non-limiting embodiments of the invention, however, provide multi-level parallel semiconductor switching system including a plurality of switching branches. The output of each respective switching branch is connected to individual input terminals included with a multi-winding filter inductor. The leakage inductances of each winding (e.g., La and Lb) may reach approximately 2% of the lump inductance such that the sum of the leakage inductances La+Lb may serve as a current sharing reactor In addition, the filter inductor according to at least one embodiment does not require a separate individually connected device serving as a current sharing reactor. Accordingly, a weight savings of approximately 8%-10% may be realized compared to conventional filter inductor assemblies. With reference now to
The current-sharing filter inductor 102 (hereinafter referred to as the filter inductor 102) is configured to share current without requiring an additional individual current sharing reactor separately connected to the filter inductor 102 as required in conventional systems. The filter inductor 102 includes a first winding 110a and a second winding 110b. In at least one embodiment, the windings 110a-110b may serve as differential mode inductors, for example.
The first winding 110a includes a first input terminal (a) and a first output terminal (a′). The first input terminal (a) is operatively connected with the first switching circuit 106a. That is, the first input terminal (a) is connected in common with both the emitter of the first semiconductor switch 108a and the collector of the second semiconductor switch 108c. In this manner, the first input terminal (a) delivers a first current (IA), which is output from the first switching circuit 106a, through the first winding 110a and to the first output terminal (a′). The second winding 110b includes a second input terminal (b) and a second output terminal (b′). The second input terminal (b) is operatively connected with the second switching circuit 106b. That is, the second input terminal (b) is connected in common with both the emitter of the third semiconductor switch 108b and the collector of the fourth semiconductor switch 108d. In this manner, the second input terminal (b) delivers a first current (IB), which output from the second switching circuit 106b, through the second winding 110b and to the second output terminal (b′).
According to a non-limiting embodiment, the first output terminal (a′) and the second output terminal (b′) are connected to one another to form a common node 112. As such, the output current (IA) delivered from the first output terminal (a′) to the load, e.g., motor, is approximately (IA+IB)/2. In a similar manner, the output current (IB) delivered from the second output terminal (b′) to the load, e.g., motor, is also approximately (IA+IB)/2. Accordingly, the common node 112 is capable of delivering a high-power combined current (IL) to drive a load such as, for example, a high-power motor. Although terminals “a” and “b” are described as inputs, it should be appreciated that the terminals (a, b) and output terminals (a′, b′) may be interchangeable, i.e., terminals a′ and b′ may be utilized as input, while terminals a and b may be utilized as outputs. Additionally, it should be appreciated that any number of switching circuits (N) may be paralleled in the same fashion, and in a similar manner the output current delivered by each of the paralleled circuits is approximately the average of their sum.
Turning to
The first inductor (La) 114a utilizes the first input terminal (a) to receive the first current signal (IA) from the first switching circuit 106a, while the second inductor (Lb) 114b utilizes the second input terminal (b) to receive the second current signal (IB) from the second switching circuit 106b. The inductor output (aa) of the first inductor (La) 114a is connected in common with the inductor output (bb) of the second inductor (Lb) 114b.
As further illustrated in
At least one embodiment provides that the first leakage inductance (La) equals, or substantially equals, the second leakage inductance (Lb). In this manner, the sum of the leakage inductances La+Lb may serve as a current sharing reactor that is inherently built-in or integrated with the filter inductor 107. In this manner, the sum of the leakage inductances (La+Lb) may limit current circulating within the switching circuits 106a-106n.
In addition, unlike conventional filter inductors, the structure of the filter inductor 107 according to at least one non-limiting embodiment provides an integrated current sharing reactor, thereby eliminating the need to connect a separate and individual current sharing reactor to the filter inductor 107. Accordingly, the overall weight of the filter inductor 107 may be reduced by approximately 8%-10%.
Turning to
The first winding 110a extends from a first proximate terminal end (e.g., a first input) to a first distal terminal end (e.g., a first output). The second winding 110b extends from a second proximate terminal end (e.g., a second input) to an opposing second distal terminal end (e.g., a second output). The first and second windings 110a-110b are configured to deliver current that is half the total current. Since the current through each set of winding is half of the total, the conductor cross-section area is half. According to at least one embodiment, the windings wrap around the core element 103 in the same direction and have an identical number of turns as further illustrated in
As described above, each winding defines an input terminal and an output terminal. Still referring to
According to a non-limiting embodiment, the first and second windings 110a-110b are wound around the core element 103 so as to form an alternating sequential arrangement with respect to one another. For example, a portion of the first winding 110a is directly interposed between adjacent portions of the second winding 110b, and vice-versa. In this manner, the first proximate terminal end (a) and first distal terminal end (a′) is interposed between adjacent portions of the second winding 110b. In a similar manner, the second proximate terminal end (b) and second distal terminal end (b′) is interposed between adjacent portions of the first winding 110a.
In addition, the filter inductor 102 is not limited to only two windings 110a-110b. For example, if four switching circuits 110a-110d the filter inductor 102 includes four windings 110a-110d. Accordingly, the filter inductor 102 may utilize a toroid-shaped core 103 that may maintain its shape as the number of windings increase. Turning now to
In this case, each switching circuit 106a-106b includes a pair of additional semiconductor switches. For example, the first switching circuit 106a includes a first outer semiconductor switch 108e and a second outer semiconductor switch 108f. The first outer semiconductor switch 108e includes a collector connected to a first voltage potential, e.g., a positive voltage (+V), and an emitter connected to the collector of the first semiconductor switch 108a. The second outer semiconductor switch 108f includes a collector connected to the emitter of the second semiconductor switch 108c, and an emitter connected to a second voltage potential, e.g., the negative voltage (−V). Similarly, the second switching circuit 106b includes a third outer semiconductor switch 108g and a fourth outer semiconductor switch 108h. The third outer semiconductor switch 108g includes a collector connected to the first voltage potential, e.g., a positive voltage (+V) and the collector of the first outer semiconductor switch 108e. The emitter of the third outer semiconductor switch 108g is connected to the collector of the third semiconductor switch 108b. The fourth outer semiconductor switch 108h includes a collector connected to the emitter of the fourth semiconductor switch 108d. The collector of the fourth outer semiconductor switch 108h is connected to the emitter of the second outer semiconductor switch 108f, and the second voltage potential, e.g., the negative voltage (−V). Accordingly, the first inductance leakage (La) associated with the first winding 110a of the filter inductor 107 is equal to, or substantially equal, to the second inductance leakage (Lb) associated with the winding 110b. In at least one embodiment, the first inductance leakage (La) is approximately 0.02 L.
Referring to
Still referring to
While the present disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to such disclosed embodiments. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the present disclosure. Additionally, while various embodiments of the present disclosure have been described, it is to be understood that aspects of the present disclosure may include only some of the described embodiments. Accordingly, the present disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
