Power supply circuit

Abstract

In a power supply circuit with redundant circuits, the reduction in the common-mode noise reduction effect of a common-mode choke coil is suppressed. [Solution] The power supply circuit 1 comprises a plurality of supply circuits that constitute a redundant circuit. The feedback wiring of each supply circuit is connected to a common node NC. The plurality of supply circuits include a common mode choke coil 30 for attenuating common mode noise generated in the supply wiring and feedback wiring. The common mode choke coil 30 has a core 31 and a plurality of coil pairs. The core 31 is provided in common to the plurality of supply circuits. The plurality of coil pairs are wound around the core 31 such that the direction of the magnetic flux generated by the current flowing through the supply wiring due to the supplied power is opposite to the direction of the magnetic flux generated by the current flowing through the feedback wiring due to the supplied power.

Description

Technical Field

[0001] The present invention relates to a power supply circuit that supplies power to a load.

Background Art

[0002] A variety of power supply circuits that supply power from a power source to equipment that operates electrically (hereinafter referred to as a load) have been widely known. It is also widely known that a current of noise called common-mode noise can be generated in the power supply circuit due to the operation of the circuit itself. In order to suppress common-mode noise, a common-mode choke coil (see Patent Document 1) can be provided in the power supply circuit. The common-mode choke coil functions as an inductance when common-mode noise occurs and is configured to attenuate common-mode noise by a high impedance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, among various power supply circuits, there are power supply circuits having a redundant circuit intentionally provided with redundancy. The redundant circuit has a plurality of supply circuits connected in parallel to each other. In such a power supply circuit, when a problem occurs in a certain supply circuit, power is continuously supplied to the load by another supply circuit. Here, in order to suppress the generation of common-mode noise in the redundant circuit, it is conceivable to provide a common-mode choke coil in any of the plurality of supply circuits. However, in this case, the inventors of the present application noticed that problems as described below may occur.

[0005] The following provides a more detailed explanation. Generally, a power supply circuit has a HOT line (supply line), which is the wiring for supplying power to the load, and an RTN line (feedback line), which is the wiring through which the current returning from the load flows. A common mode choke coil has a core, a first coil, and a second coil. The first coil is a coil wound around the core in the middle of the supply line. The second coil is a coil wound around the core in the same direction as the first coil in the middle of the feedback line. To distinguish the current flowing for the operation of the power supply circuit from noise current, it will be referred to as the normal current below. Generally, the magnitude of the normal current flowing through the first coil and the magnitude of the normal current flowing through the second coil are approximately equal. In this case, the magnetic flux generated in the core by the normal current flowing through the first coil and the magnetic flux generated in the core by the normal current flowing through the second coil cancel each other out. Furthermore, when a current (current noise) due to common-mode noise flows through a common-mode choke coil, the magnetic flux generated in the core by the current noise flowing through the first coil and the magnetic flux generated in the core by the current noise flowing through the second coil reinforce each other. As a result, a common-mode choke coil typically functions as a large inductance only with respect to common-mode noise.

[0006] On the other hand, if the power supply circuit has redundancy, at least a portion of the feedback wiring may branch (details will be explained with reference to the figures in the embodiments described later). In this case, the normal current returning from the load is divided into multiple feedback wires. In such a configuration, an imbalance may occur between the normal current flowing through the first coil and the normal current flowing through the second coil in multiple common-mode choke coils. As a result, the magnetic flux generated in the core due to the normal current may not be sufficiently canceled out, and the magnetic flux in the core may easily saturate. Under these circumstances, when common-mode noise occurs, the magnetic flux in the core may saturate, the inductance value may not become sufficiently large, and a problem may arise in which the common-mode noise cannot be sufficiently reduced.

[0007] The objective of the present invention is to suppress the reduction in the common-mode noise reduction effect of a common-mode choke coil in a power supply circuit having redundant circuits. [Means for solving the problem]

[0008] The power supply circuit of the first invention is a power supply circuit that supplies power to a load that performs a predetermined function by electricity, and comprises a plurality of supply circuits each having a supply wiring through which power is supplied from a power source to the load and a feedback wiring through which current returning from the load flows, and which are connected in parallel to each other to form a redundant circuit, wherein the plurality of feedback wirings are branched from each other and connected to a common node having a common potential, and the plurality of supply circuits include a common mode choke coil for attenuating common mode noise generated in the supply wiring and the feedback wiring, wherein the common mode choke coil comprises a core provided in common to the plurality of supply circuits, and a plurality of pairs of coils wound around the core such that the direction of the magnetic flux generated by the current flowing in the supply wiring due to the supplied power and the direction of the magnetic flux generated by the current flowing in the feedback wiring due to the supplied power are in opposite directions, and which are provided corresponding to each of the plurality of supply circuits.

[0009] In this invention, since multiple feedback lines branch off from each other and are connected to a common node, the current returning from the load to the multiple feedback lines is divided. In such a configuration, if a common-mode choke coil is provided for each supply circuit, there is a risk that the imbalance between the current from the power source to the load and the current returning from the load will become large in each common-mode choke coil. However, in this invention, multiple pairs of coils, each corresponding to a multiple supply circuit, are wound together on a single core. The sum of the currents flowing through the multiple supply lines and the sum of the currents flowing through the multiple feedback lines are approximately equal. Furthermore, the direction of the magnetic flux generated by the current flowing through the supply lines due to the supplied power and the direction of the magnetic flux generated by the current flowing through the feedback lines due to the supplied power are opposite to each other. Therefore, when the above-mentioned normal current flows through multiple pairs of coils, the magnetic flux generated in the core due to the normal current can be effectively canceled out. This suppresses the saturation of the magnetic flux in the core when common-mode noise occurs. Consequently, in a power supply circuit with redundant circuits, the reduction in the common-mode noise reduction effect by the common-mode choke coil can be suppressed.

[0010] The power supply circuit of the second invention is characterized by comprising, in the first invention, a first power supply which is the power supply provided in correspondence with one or more first power supply circuits among the plurality of power supply circuits, and a second power supply which is the power supply provided in correspondence with one or more second power supply circuits which are different from the one or more first power supply circuits among the plurality of power supply circuits.

[0011] In this invention, even if one power supply fails, power can be supplied to the load using the other power supply. Therefore, the power supply circuit of this invention can be applied to equipment that requires high reliability.

[0012] The power supply circuit of the third invention is characterized in that, in the first or second invention, the redundant circuit has a parallel redundant circuit, and the parallel redundant circuit has two or more supply circuits from the plurality of supply circuits, each configured to operate continuously under normal conditions.

[0013] In circuits known as redundant circuits, redundancy is achieved through various means. One type of redundancy is "standby redundancy," where another circuit starts operating when one circuit fails. Another type of redundancy is "parallel redundancy," where multiple circuits are kept running at all times, and when one circuit fails, another circuit instantly starts supplying power to the load. The power supply circuit of the present invention is equipped with a parallel redundant circuit (parallel redundant circuit). Therefore, the power supply circuit of the present invention can be applied to equipment that requires that the power supply to the load be kept uninterrupted for even a moment. [Brief explanation of the drawing]

[0014] [Figure 1] This is a block diagram of the power supply circuit according to this embodiment. [Figure 2] This is a block diagram of a simple power supply circuit equipped with a common mode choke coil. [Figure 3] This is a schematic diagram of a typical common-mode choke coil. [Figure 4] This is a circuit diagram of a power supply circuit equipped with two common-mode choke coils. [Figure 5] This is a circuit diagram of the power supply circuit according to this embodiment. [Figure 6] This is a schematic diagram of a common mode choke coil according to this embodiment. [Figure 7] This is a circuit diagram of a modified power supply circuit. [Modes for carrying out the invention]

[0015] Embodiments of the present invention will now be described. Figure 1 is a block diagram of the power supply circuit 1 according to this embodiment.

[0016] (Outline of the power supply circuit) The outline of the power supply circuit 1 will be described. The power supply circuit 1 shown in FIG. 1 is an electric circuit (hereinafter, also simply referred to as a circuit) that can be applied to a flying object such as a rocket or an aircraft. The power supply circuit 1 is connected to the load 4 and supplies power to the load 4. The load 4 is a device or element that exhibits a predetermined function by electricity. The load 4 may be, for example, a known electromagnetic valve. The load 4 may be electrically connected to a control device (not shown).

[0017] As shown in FIG. 1, the power supply circuit 1 includes a first supply circuit 2 and a second supply circuit 3. The first supply circuit 2 is a circuit that connects the first power source 11 to the load 4. The second supply circuit 3 is a circuit that connects the second power source 21 to the load 4.

[0018] The first supply circuit 2 and the second supply circuit 3 are connected in parallel with each other to form a redundant circuit. That is, the power supply circuit 1 is configured such that even if one of the first supply circuit 2 and the second supply circuit 3 fails, the other operates to maintain the power supply to the load 4. More specifically, it will be described later.

[0019] (Configuration of the first supply circuit and the second supply circuit) The configurations of the first supply circuit 2 and the second supply circuit 3 will be described. The first supply circuit 2 includes a first power source 11, a first supply wiring 12, a shared supply wiring 13, a shared feedback wiring 14, a first feedback wiring 15, a switch 16, and a diode 17. For the sake of convenience of explanation, in the first supply wiring 12 and the shared supply wiring 13, the side closer to the first power source 11 is referred to as the upstream side, and the side closer to the load 4 is referred to as the downstream side. Also, in the shared feedback wiring 14 and the first feedback wiring 15, the side closer to the load 4 is referred to as the upstream side, and the side closer to the first power source 11 is referred to as the downstream side.

[0020] The first power supply 11 is, for example, a battery for supplying power to the load 4. More specifically, the first power supply 11 is a power supply for applying a predetermined first voltage to the load 4. The first voltage is a positive voltage. The first power supply 11 is connected to the load 4 via the first supply wiring 12, the shared supply wiring 13, the shared feedback wiring 14, and the first feedback wiring 15. The first supply wiring 12 is a part of the wiring (generally called the HOT line) for supplying power from the first power supply 11 to the load 4. The first supply wiring 12 extends downstream from the first power supply 11. The first supply wiring 12 joins the second supply wiring 22 at the node N1 disposed downstream of the diode 17. The shared supply wiring 13 is a part of the HOT line of the first supply circuit 2. The shared supply wiring 13 is disposed downstream of the node N1. The shared feedback wiring 14 is a part of the wiring (generally called the RTN line) through which the current returning from the load 4 to the first power supply 11 or the second power supply 21 flows. The shared feedback wiring 14 extends downstream from the load. The shared feedback wiring 14 branches into the first feedback wiring 15 and the second feedback wiring 23 at the node N2. The first feedback wiring 15 is a part of the RTN line of the first supply circuit 2. The first feedback wiring 15 is disposed downstream of the node N2. The switch 16 is a switching element capable of turning on and off the connection between the first power supply 11 and the load 4 in the first supply wiring 12. In the present embodiment, the switch 16 is always on. The diode 17 is a known rectifying element disposed on the first supply wiring 12. The diode 17 allows current to flow only downstream in the first supply wiring 12 and prevents the current from flowing backward upstream (toward the first power supply 11 side).

[0021] The second supply circuit 3 includes the second power supply 21, the second supply wiring 22, the above-described shared supply wiring 13, the above-described shared feedback wiring 14, the second feedback wiring 23, the switch 24, and the diode 25. For the sake of convenience of explanation, in the second supply wiring 22, the side closer to the second power supply 21 is called the upstream side, and the side closer to the load 4 is called the downstream side. Also, in the second feedback wiring 23, the side closer to the load 4 is called the upstream side, and the side closer to the second power supply 21 is called the downstream side.

[0022] The second power supply 21 is, for example, a battery for supplying power to the load 4. More specifically, the second power supply 21 is a power source for applying a predetermined second voltage to the load 4. The second voltage is a positive voltage lower than the first voltage. More specifically, it is preferable that the power supply voltage of the second power supply 21 is lower than the power supply voltage of the first power supply 11. The second power supply 21 is connected to the load 4 via a second supply line 22, a shared supply line 13, a shared feedback line 14, and a second feedback line 23. The second supply line 22 is part of the HOT line in the second supply circuit 3. The second supply line 22 merges with the first supply line 12 at node N1, which is located downstream of the diode 25. The second feedback line 23 is part of the RTN line in the second supply circuit 3. The second feedback line 23 is located downstream of node N2. The switch 24 is a switch element that can turn the connection between the second power supply 21 and the load 4 on and off in the second supply line 22. In this embodiment, switch 24 is always on. Diode 25 is a known rectifier element placed on the second supply line 22. Diode 25 allows current to flow only downstream in the second supply line 22, preventing current from flowing back upstream (to the second power supply 21).

[0023] The first supply circuit 2 and the second supply circuit 3 correspond to the plurality of supply circuits of the present invention. The first power supply 11 and the second power supply 21 each correspond to the power supply of the present invention. The first supply wiring 12, the second supply wiring 22 and the shared supply wiring 13 each correspond to the supply wiring of the present invention. The first feedback wiring 15, the second feedback wiring 23 and the shared feedback wiring 14 each correspond to the feedback wiring of the present invention.

[0024] (Operation of the power supply circuit) Next, the operation of power supply circuit 1 will be briefly explained. Both the first supply circuit 2 and the second supply circuit 3 are configured to operate continuously under normal conditions. In other words, the first supply circuit 2 and the second supply circuit 3 constitute a so-called parallel redundant circuit. Assume that both the first supply circuit 2 and the second supply circuit 3 are operating normally. In this case, the first supply circuit 2 and the second supply circuit 3 are configured such that the potential of the portion of the first supply wiring 12 downstream of the diode 17 is higher than the potential of the portion of the second supply wiring 22 upstream of the diode 25. As a result, no current flows to the portion of the second supply wiring 22 downstream of the diode 25. That is, current flows to the load 4 only from the first power supply 11.

[0025] Next, let's consider a scenario where the operation of the first supply circuit 2 malfunctions due to a failure of the first power supply 11 or a break in the wiring within the first supply circuit 2. In this case, only the second supply circuit 3 operates, and current flows from the second power supply 21 to the load 4. Thus, in this embodiment, when the first supply circuit 2 is operating normally, power is supplied from the first supply circuit 2 to the load 4. Also, when the first supply circuit 2 stops operating normally, power is supplied from the second supply circuit 3 immediately (i.e., with virtually no time lag) to the load 4.

[0026] Incidentally, if noise is generated in the power supply circuit 1 due to the operation of the circuit itself, there is a risk that this noise may be released to the outside and cause malfunctions in other equipment. In particular, countermeasures against common-mode current (common-mode noise), which is noise current flowing in the same direction (towards the power supply side or the load 4 side) on the HOT line and RTN line, are generally considered important. Therefore, although not shown in Figure 1, the power supply circuit 1 is equipped with noise reduction elements, which will be described later.

[0027] (Noise reduction element) Common mode choke coils, which attenuate common mode noise, are widely known as a type of noise reduction element. A typical common mode choke coil 105 will be described with reference to Figures 2 and 3. Figure 2 is a block diagram of a power supply circuit 100 equipped with a common mode choke coil 105. Figure 3 is a schematic diagram of a common mode choke coil 105.

[0028] The power supply circuit 100 is configured to supply power to the load 101. The power supply circuit 100 comprises, for example, a power supply 102, a supply wiring 103, a feedback wiring 104, and a common mode choke coil 105. For the sake of simplicity, unlike power supply circuit 1, power supply circuit 100 is assumed to be a simple circuit having only one power supply 102. The illustration and description of the switches and diodes mentioned above are omitted. The power supply 102 is, for example, a known battery. The supply wiring 103 is a HOT wire that supplies power from power supply 102 to the load 101. In power supply circuit 100, the supply wiring 103 is, for example, continuously connected from power supply 102 to load 101. That is, the supply wiring 103 has a partial wiring 107 which is the part upstream of the common mode choke coil 105, and a partial wiring 108 which is the part downstream of the common mode choke coil 105. The feedback wiring 104 is an RTN line through which the current returning from the load 101 flows. In the power supply circuit 100, the feedback wiring 104 is continuously connected, for example, from the load 101 to the power supply 102. In other words, the feedback wiring 104 has a partial wiring 109 which is upstream of the common mode choke coil 105, and a partial wiring 110 which is downstream of the common mode choke coil 105. The feedback wiring 104 is connected, for example, to a common electrode (not shown) having a predetermined common potential.

[0029] As shown in Figure 2, the common mode choke coil 105 is located between the power supply 102 and the load 101. As shown in Figure 3, the common mode choke coil 105 includes part of the supply wiring 103 and part of the feedback wiring 104. The common mode choke coil 105 has a core 106, a supply coil 103C, and a feedback coil 104C.

[0030] The core 106 is a core component made of a magnetic material (ferromagnetic material), such as ferrite. The supply coil 103C is made up of a part of the supply wiring 103. The supply coil 103C is wound around the core 106 in a predetermined direction. The feedback coil 104C is made up of a part of the feedback wiring 104. The feedback coil 104C is wound around the core 106 in the same direction as the supply coil 103C. The number of turns of the supply coil 103C and the number of turns of the feedback coil 104C are generally equal.

[0031] (Operation of a common mode choke coil) The operation of a typical common-mode choke coil 105 will be explained with reference to Figure 3. We will assume a state where common-mode noise is generated in the power supply circuit 100 due to external electromagnetic waves or other influences. More specifically, for example, a high-frequency current IaH is generated in the supply wiring 103, and a high-frequency current IaR is generated in the feedback wiring 104. Currents IaH and IaR are in phase with each other. At this time, the current IaH flowing through the supply-side coil 103C generates a magnetic flux FaH within the core 106, and the current IaR flowing through the feedback-side coil 104C generates a magnetic flux FaR within the core 106. The direction of magnetic flux FaH and magnetic flux FaR are the same (clockwise in Figure 3). Therefore, magnetic fluxes FaH and FaR reinforce each other, generating a large magnetic flux within the core 106. The inductance of the common-mode choke coil 105 increases in proportion to the magnitude of these magnetic fluxes. Inductance functions as a high impedance against high-frequency noise. Therefore, common-mode noise is effectively attenuated by the common-mode choke coil 105.

[0032] Furthermore, with respect to the current that normally flows through the power supply circuit 100 due to the power supply 102 (hereinafter referred to as the normal current), the common mode choke coil 105 behaves as follows. For example, a current IbH flows as the normal current through the supply wiring 103, and a current IbR flows as the normal current through the feedback wiring 104. The magnitudes of current IbH and current IbR are generally approximately equal. Also, current IbH and current IbR are in opposite directions. At this time, a magnetic flux FbH is generated in the core 106 by the current IbH flowing through the supply-side coil 103C, and a magnetic flux FbR is generated in the core 106 by the current IbR flowing through the feedback-side coil 104C. The magnitudes of magnetic flux FbH and magnetic flux FbR are approximately equal. The directions of magnetic flux FbH and magnetic flux FbR are in opposite directions. Therefore, magnetic flux FbH and magnetic flux FbR cancel each other out. Therefore, the common mode choke coil 105 has virtually no effect on the normal current and is not affected by the normal current.

[0033] (Application of common mode choke coils to redundant circuits) Here, it is conceivable to also apply the common mode choke coil 105 to the redundant power supply circuit 1. However, the following problems arise with a configuration in which a common mode choke coil 105 is simply placed in each of the first supply circuit 2 and the second supply circuit 3 described above. This will be explained in detail with reference to Figure 4. Figure 4 is a circuit diagram of a power supply circuit 200 equipped with two common mode choke coils 105. The power supply circuit 200 is a reference circuit for comparison with the power supply circuit 1 of this embodiment.

[0034] As shown in Figure 4, the power supply circuit 200 comprises a first supply circuit 201 and a second supply circuit 202. The first supply circuit 201 is the same circuit as the first supply circuit 2 described above, except that it has a common mode choke coil 105. The second supply circuit 202 is the same circuit as the second supply circuit 3 described above, except that it has a common mode choke coil 105.

[0035] As shown in Figure 4, the first supply circuit 201, like the power supply circuit 100, has a common mode choke coil 105. The second supply circuit 202 also has a common mode choke coil 105.

[0036] More precisely, as shown in Figure 4, the downstream terminal of the first feedback wiring 15 is connected to a common node NC having a common potential with the power supply circuit 200, for example. Similarly, the downstream terminal of the second feedback wiring 23 is also connected to a common node NC, for example.

[0037] Assume that both the first supply circuit 201 and the second supply circuit 202 are operating normally. In this case, as described above regarding the operation of power supply circuit 1, current flows from the first power supply 11 to the load 4 (see the normal current Ip shown in Figure 4). Also, as mentioned above, the shared feedback wiring 14 branches into the first feedback wiring 15 and the second feedback wiring 23 at node N2. As a result, the current flowing from the load 4 toward the common node NC is divided into the normal current In1 flowing through the first feedback wiring 15 and the normal current In2 flowing through the second feedback wiring 23. This creates an imbalance between the normal current Ip flowing through the first supply wiring 12 and the normal current In1 flowing through the first feedback wiring 15. That is, a significant difference arises between the magnitude of the normal current Ip and the magnitude of the normal current In1. As a result, the magnetic flux generated in the core 106 due to the normal current is not sufficiently canceled out, and the magnetic flux in the core 106 may become prone to saturation. Under these circumstances, when common-mode noise occurs, the magnetic flux within the core saturates, preventing the inductance from becoming sufficiently large, resulting in a problem where common-mode noise cannot be adequately reduced. Therefore, in order to suppress the decrease in the effectiveness of common-mode noise reduction, the power supply circuit 1 is configured as follows.

[0038] (Detailed configuration of the power supply circuit) The detailed configuration of power supply circuit 1 will be described with reference to Figures 5 and 6. Figure 5 is a circuit diagram of power supply circuit 1. Figure 6 is a schematic diagram of the common mode choke coil 30 provided in power supply circuit 1. Similar to power supply circuit 200, in power supply circuit 1, the first feedback wiring 15 and the second feedback wiring 23 are connected to a common node NC (see Figure 5).

[0039] As shown in Figure 5, the power supply circuit 1 includes one common-mode choke coil 30. As shown in Figure 6, the common-mode choke coil 30 has a core 31 and multiple pairs of coils (a pair of a first supply coil 12C and a first feedback coil 15C, and a pair of a second supply coil 22C and a second feedback coil 23C). The core 31 is a core member common to the first supply circuit 2 and the second supply circuit 3. The first supply coil 12C is included in the first supply wiring 12. The first feedback coil 15C is included in the first feedback wiring 15. The second supply coil 22C is included in the second supply wiring 22. The second feedback coil 23C is included in the second feedback wiring 23. The first supply coil 12C, the first feedback coil 15C, the second supply coil 22C, and the second feedback coil 23C are all wound around the core 31. The first supply coil 12C, the first feedback coil 15C, the second supply coil 22C, and the second feedback coil 23C have the same number of turns. The first supply coil 12C and the second supply coil 22C are wound, for example, in the same direction. The first feedback coil 15C and the second feedback coil 23C are wound, for example, in the same direction. The first supply coil 12C and the first feedback coil 15C are wound, for example, in the same direction. The second supply coil 22C and the second feedback coil 23C are wound, for example, in the same direction. Each coil is wound such that the magnetic flux generated by the normal current flowing through these coils cancels out.

[0040] The following provides a more detailed explanation. As shown in Figure 6, the current flowing through the first supply coil 12C due to the supplied power is called the normal current I12. The current flowing through the first return coil 15C due to the supplied power is called the normal current I15. The current flowing through the second supply coil 22C due to the supplied power is called the normal current I22. The current flowing through the second return coil 23C due to the supplied power is called the normal current I23. The magnetic fluxes generated by the normal currents I12, I15, I22, and I23 are called magnetic fluxes F12, F15, F22, and F23, respectively. The sum of the normal currents I12 and I22 is approximately equal to the sum of the normal currents I15 and I23 (more precisely, the normal currents I12 or I22 are practically zero). As a result, the sum of the magnitudes of magnetic flux F12 and F22 is approximately equal to the sum of the magnitudes of magnetic flux F15 and F23. Furthermore, the direction of magnetic flux F12 is the same as the direction of magnetic flux F22. The direction of magnetic flux F15 is the same as the direction of magnetic flux F23. Magnetic flux F12 and magnetic flux F15 are opposite to each other. Magnetic flux F22 and magnetic flux F23 are opposite to each other. As a result, the magnetic flux generated in the core 31 by the normal current cancels out. If the common mode choke coil 30 is configured in this way, the direction in which each coil is wound around the core 31 is not limited to those described above.

[0041] As described above, multiple pairs of coils, each corresponding to a multiple supply circuit (first supply circuit 2 and second supply circuit 3), are wound together on a single core 31. The sum of the currents flowing through the multiple supply lines is approximately equal to the sum of the currents flowing through the multiple feedback lines. Furthermore, the direction of the magnetic flux generated by the current flowing through the supply lines due to the supplied power and the direction of the magnetic flux generated by the current flowing through the feedback lines due to the supplied power are opposite to each other. Therefore, when normal current flows through multiple pairs of coils, the magnetic flux generated within the core 31 due to the normal current can be effectively canceled out. This suppresses the saturation of the magnetic flux within the core 31 when common-mode noise occurs. Consequently, in a power supply circuit 1 with redundant circuits, the reduction in the common-mode noise reduction effect of the common-mode choke coil 30 can be suppressed.

[0042] Furthermore, the power supply circuit 1 includes a first power supply 11 and a second power supply 21. This allows power to be supplied to the load 4 using the other power supply even if one power supply fails. Therefore, the power supply circuit 1 of the present invention can be applied to equipment that requires high reliability.

[0043] Furthermore, the power supply circuit 1 is a parallel redundant circuit that includes a first supply circuit 2 and a second supply circuit, both of which operate continuously when in a normal state. Therefore, the power supply circuit 1 of the present invention can be applied to equipment that requires that the power supply to the load 4 be kept uninterrupted for even a moment.

[0044] Next, modified examples of the above embodiments will be described. However, components having the same configuration as the above embodiments will be denoted by the same reference numerals and their descriptions will be omitted as appropriate.

[0045] (1) In the above embodiment, the first supply circuit 2 and the second supply circuit 3 are assumed to constitute a parallel redundant circuit. However, this is not limited to this. The first supply circuit 2 and the second supply circuit 3 may, for example, constitute a so-called standby redundant circuit. That is, when the first supply circuit 2 is operating normally, the switch 24 of the second supply circuit 3 may be off. The switch 24 may be configured to be on only when a malfunction occurs in the operation of the first supply circuit 2. However, in such a configuration, compared to the power supply circuit 1 described above, there will be a slight time lag between when a malfunction occurs in the operation of the first supply circuit 2 and when power is supplied from the second supply circuit 3 to the load 4. Therefore, the types of equipment to which the modified power supply circuit (not shown) can be applied may be limited compared to the power supply circuit 1.

[0046] (2) In the embodiments described above, the power supply voltage of the second power supply 21 was set lower than the power supply voltage of the first power supply 11. However, this is not the case. That is, the first voltage described above is a voltage that takes into account the power supply voltage of the first power supply 11 and the voltage drop by the diode 17. The second voltage is a voltage that takes into account the power supply voltage of the second power supply 21 and the voltage drop by the diode 25. For example, the power supply voltage of the second power supply 21 may be approximately equal to the power supply voltage of the first power supply 11. In this case, the diodes 17 and 25 may be designed such that the voltage drop by the diode 25 is greater than the voltage drop by the diode 17.

[0047] (3) In the embodiments described above, the power supply circuit 1 is provided with a first power supply 11 and a second power supply 21. However, it is not limited to this. This will be explained with reference to Figure 7. Power supply circuit 1A includes a first supply circuit 2A and a second supply circuit 3A. Power supply circuit 1A includes, for example, one power supply 11A. Power supply 11A is a battery provided in common to the first supply circuit 2A and the second supply circuit 3A. As an example of a circuit, in power supply circuit 1A, a shared supply wiring 41 is provided downstream of power supply 11A. The shared supply wiring 41 branches, for example, at node N3 into a first supply wiring 42 of the first supply circuit 2A and a second supply wiring 44 of the second supply circuit 3A. Also, in the first supply circuit 2A, a first feedback wiring 43 is located downstream of node N2. In the second supply circuit 3A, a second feedback wiring 45 is located downstream of node N2. The first feedback wiring 43 and the second feedback wiring 45 merge at node N4. A shared feedback wiring 46 is located downstream of node N4. A power supply circuit 47 is provided between, for example, switch 16 and diode 17 in the first supply circuit 2A. A power supply circuit 48 is provided between, for example, switch 24 and diode 25 in the second supply circuit 3A. Power supply circuits 47 and 48 may be, for example, known DC / DC converter circuits. In this case, when power supply circuits 47 and 48 are, for example, known step-down chopper circuits, the first supply circuit 2 and the second supply circuit 3 constitute a parallel redundant circuit. In such a configuration, a common-mode choke coil 30 may be provided.

[0048] (4) In the embodiments described above, the power supply circuit 1 is provided with two supply circuits. However, it is not limited to this. Three or more supply circuits (not shown) that constitute a redundant circuit by being connected in parallel may be provided. The number of power supplies (not shown) may be one or more. In such a configuration, the core 31 of the common mode choke coil 30 must be a core common to the multiple supply circuits. In addition, in each of the multiple coil pairs of the common mode choke coil 30, the direction of the magnetic flux generated by the current flowing through the HOT line due to the supplied power and the direction of the magnetic flux generated by the current flowing through the RTN line due to the supplied power must be opposite. [Explanation of Symbols]

[0049] 1 Power supply circuit 2 1st supply circuit (supply circuit) 3 2nd supply circuit (supply circuit) 4 load 11 1st power supply (power supply) 12 1st supply wiring (supply wiring) 12C supply side coil (coil) 15. First feedback wiring (feedback wiring) 15C Feedback coil (coil) 21 2nd power supply (power supply) 22 2nd supply wiring (supply wiring) 22C supply side coil (coil) 23. Second feedback wiring (feedback wiring) 23C Feedback coil (coil) 30 Common Mode Choke Coils 31 cores F12 magnetic flux F15 Magnetic Flux F22 Magnetic Flux F23 Magnetic Flux I12 Normal current (current) I15 Normal current (current) I22 Normal current (current) I23 Normal current (current) NC Common Node

Claims

1. A power supply circuit that supplies power to a load that performs a predetermined function using electricity, The system comprises multiple supply circuits, each having a supply line through which power is supplied from the power source to the load, and a feedback line through which current returns from the load, and these circuits are connected in parallel to each other to form a redundant circuit. Multiple of the aforementioned feedback lines are branched from each other and connected to a common node having a common potential. The aforementioned multiple supply circuits are Includes a common mode choke coil for attenuating common mode noise generated in the supply wiring and the feedback wiring, The common mode choke coil is, A core provided in common to the plurality of supply circuits, A power supply circuit characterized by having a plurality of pairs of coils, each provided corresponding to a plurality of power supply circuits, which are wound around the core such that the direction of the magnetic flux generated by the current flowing through the power supply wiring due to the supplied power is opposite to the direction of the magnetic flux generated by the current flowing through the feedback wiring due to the supplied power.

2. A first power supply, which is the power supply provided in correspondence with one or more first supply circuits among the plurality of supply circuits, The power supply circuit according to claim 1, further comprising a second power supply, which is a power supply provided in correspondence with one or more second power supply circuits, which are separate from the one or more first power supply circuits among the plurality of power supply circuits.

3. The redundant circuit has parallel redundant circuits, The aforementioned parallel redundant circuit is The power supply circuit according to claim 1 or 2, characterized in that it has two or more supply circuits among the plurality of supply circuits, each configured to operate continuously under normal conditions.

Images