Multi-output power supply device

Abstract

Provided is a multi-output power supply device in which current is not unbalanced in a line filter circuit included in each of a plurality of power supply units. A multi-output power supply device (10A) is provided with a first power supply unit (20) that outputs a first DC voltage, a second power supply unit (30A) that outputs a second DC voltage, and a first switch (11), and is capable of operating in a first mode in which both the first DC voltage and the second DC voltage are output, and a second mode in which only the second DC voltage is output. The second power supply unit (30A) includes a second switch (38) provided on a path (second low-potential-side DC line (36)) for a current flowing from the second voltage conversion circuit (34) to the second line filter circuit (31). The first switch (11) is configured to be in a closed state in the first mode and in an open state in the second mode. The second switch (38) is configured to be in an open state in the first mode and in a closed state in the second mode.

Description

Technical Field

[0001] This invention relates to a multi-output power supply device capable of outputting multiple different DC voltages. Background Technology

[0002] Conventionally, various electronic devices have used multi-output power supply units that output multiple different DC voltages. For example, in image forming apparatus (copiers), multi-output power supply units are used that output a first DC voltage (e.g., 24 [V]) for driving the paper feeding mechanism, etc., and a second DC voltage (e.g., 5 [V]) for driving control circuits with lower power consumption than the paper feeding mechanism, etc.

[0003] Figure 5 A conventional multi-output power supply device 100 is shown. The multi-output power supply device 100 includes: a line filter circuit 101, one end of which is connected to an AC power supply G such as a commercial AC power supply; a first power supply unit 110, which is connected to the other end of the line filter circuit 101 via a switch 102 that is in an open or closed state according to an external signal S1; and a second power supply unit 120, which is directly connected to the other end of the line filter circuit 101.

[0004] The first power supply unit 110 includes a first diode bridge circuit 111, a power factor improvement circuit 112, a first voltage conversion circuit 113, a first smoothing capacitor 116, and a first high-potential side DC line 114 and a first low-potential side DC line 115 connecting the power factor improvement circuit 112 and the first voltage conversion circuit 113. When the switch 102 is closed, the first power supply unit 110 outputs 24V.

[0005] The second power supply unit 120 includes a second diode bridge circuit 121, a second voltage conversion circuit 123, a second smoothing capacitor 126, a second high-potential side DC line 124 and a second low-potential side DC line 125 connecting the second diode bridge circuit 121 and the second voltage conversion circuit 123. Regardless of the state of the switch 102, the second power supply unit 120 always outputs 5V.

[0006] The multi-output power supply device 100 further includes: a high-potential side interconnection line 103 connecting the high-potential side DC lines 114 and 124, a low-potential side interconnection line 104 connecting the low-potential side DC lines 115 and 125, and a diode 105 disposed on the high-potential side interconnection line 103. When the first power supply unit 110 outputs 24 [V], the high-potential side interconnection line 103 and the diode 105 replace the second diode bridge circuit 121 to supply current to the second voltage conversion circuit 123.

[0007] In this multi-output power supply device 100, when the switch 102 is closed, the sum of the circuit current of the first power supply unit 110 and the circuit current of the second power supply unit 120 flows through the line filter circuit 101. Therefore, in this multi-output power supply device 100, when the power consumption of a load circuit (not shown) receiving a 24V or 5V supply increases, in order to reduce the resistance of the line filter circuit 101, it is necessary to thicken the windings of the line filter circuit 101 or increase the core size. However, when the windings are thickened or the core size is increased, the size and cost of the line filter circuit 101 increase.

[0008] Regarding this issue, referring to the structure described in Patent Document 1, which includes filters in each power supply section, as long as such a method is adopted... Figure 6 The structure of the multi-output power supply device 100' shown can eliminate this problem, that is, the line filter circuit 101 is omitted, a first power supply unit 100' including a first line filter circuit 117 is used instead of a first power supply unit 110, and a second power supply unit 120' including a second line filter circuit 127 is used instead of a second power supply unit 120.

[0009] However, when this structure is used, the current flowing through the first line filter circuit 117 and the current flowing through the second line filter circuit 127 may sometimes become unbalanced when the switch 102 is in the closed state.

[0010] For example, if the current flowing from the first power supply section 100' to the load circuit (not shown) is Ia, and the current flowing from the second power supply section 120' to the load circuit (not shown) is Ib, then the current flowing from left to right in the first line filter circuit 117 is Ia + Ib. This is because the voltage output of the power factor improvement circuit 112 of the first power supply section 100' is higher than the voltage output of the second diode bridge circuit 121 of the second power supply section 120', so the current does not flow from the AC power supply G to the second power supply section 120', but rather from the first power supply section 100' to the second power supply section 120'. On the other hand, since the impedance of the low-potential side DC lines 115 and 125 is low and they are at approximately the same potential, the current flowing from the load circuit (not shown) to the second power supply circuit 120' is divided into the current flowing through the first line filter circuit 117 and the current flowing through the second line filter circuit 127. Therefore, in the first line filter circuit 117, the current flowing from right to left is Ia + Ib1 (Ib1 < Ib), and the current flowing through this circuit 117 generates a difference of Ib - Ib1. Similarly, in the second line filter circuit 127, the current flowing from right to left is Ib2 (where Ib2 = Ib - Ib1), and the current flowing through this circuit 127 generates a difference of Ib2. Additionally, at this time, a forward current Ib flows through diode 105. When the current flowing through the first line filter circuit 117 and the current flowing through the second line filter circuit 127 becomes unbalanced, additional problems arise, such as the first line filter circuit 117 and the second line filter circuit 127 failing to fully perform their filtering functions.

[0011] Figure 7 This diagram illustrates the conducted noise characteristics of the multi-output power supply device 100' when switch 102 is closed. Waveform W1 is the quasi-peak value (QP value) obtained through measurement, and waveform W2 is the average value (AV value) obtained through measurement. Additionally, line L1 represents the limit value of QP as specified by a standard (e.g., VCCI Class B), and line L2 represents the limit value of AV as specified by a standard (e.g., VCCI Class B). This diagram shows that the first line filter circuit 117 and the second line filter circuit 127 cannot fully perform their filtering functions, resulting in QP and AV values ​​exceeding the limits.

[0012] In addition, it should be noted that Figure 6 The multi-output power supply device 100' shown was conceived by the inventors during the development of this invention and is not prior art.

[0013] Existing technical documents

[0014] Patent documents

[0015] Patent Document 1: Japanese Patent No. 3822779 Summary of the Invention

[0016] The technical problem that the invention aims to solve

[0017] The present invention was made in view of the above-mentioned reasons, and the technical problem is to provide a multi-output power supply device in which the current is not unbalanced in the line filter circuits included in each of the multiple power supply sections.

[0018] Technical solutions for solving technical problems

[0019] To solve the aforementioned technical problems, the multi-output power supply device of the present invention is a device comprising a first power supply unit that outputs a first DC voltage and a second power supply unit that outputs a second DC voltage, and capable of operating in a first mode that outputs both the first DC voltage and the second DC voltage, and in a second mode that outputs only the second DC voltage. The first power supply unit comprises: a first line filter circuit connected to an AC power supply via a first switch; a first DC conversion circuit that DC-converts the AC voltage output from the first line filter circuit, including a diode bridge circuit; and a first voltage conversion circuit that converts the DC voltage output from the first DC conversion circuit into the first DC voltage. The second power supply unit comprises: a second line filter circuit connected to an AC power supply; and a second DC conversion circuit that DC-converts the second line filter circuit into the first DC voltage. The AC voltage output of the filter circuit is converted to DC voltage, including a diode bridge circuit; a second voltage conversion circuit that converts the DC voltage output of the second DC conversion circuit into a second DC voltage; and a second power supply current control unit that is provided on the current path from the second voltage conversion circuit to the second line filter circuit. The multi-output power supply device also includes a second power supply interconnection line that connects the outputs of the first DC conversion circuit and the second DC conversion circuit to each other. The DC voltage output by the first DC conversion circuit in the first mode is higher than the DC voltage output by the second DC conversion circuit. The first switch is configured to be closed in the first mode and open in the second mode. The second power supply current control unit is configured to be non-conducting in the first mode and conducting in the second mode.

[0020] According to this structure, when the multi-output power supply device operates in the first mode, the first DC conversion circuit outputs a DC voltage higher than the second DC conversion circuit outputs, and the current path from the second voltage conversion circuit to the second line filter circuit is cut off by the second power supply section using a current control unit. That is, according to this structure, all current flowing from the AC power supply to the first and second voltage conversion circuits, and all current flowing from the first and second voltage conversion circuits to the AC power supply, passes through the first line filter circuit but not the second line filter circuit. Therefore, according to this structure, current balance can be achieved in the first and second line filter circuits.

[0021] The current control unit for the second power supply section of the aforementioned multi-output power supply device may, for example, be a second switch configured to be in an open state in the first mode and in a closed state in the second mode.

[0022] According to this structure, when the multi-output power supply device operates in the first mode, the path of current from the second voltage conversion circuit to the second line filter circuit can be cut off by the second switch.

[0023] The first and second switches of the aforementioned multi-output power supply device are in an open or closed state, for example, depending on the same or different external signals.

[0024] The current control unit of the second power supply section of the aforementioned multi-output power supply device may be, for example, a diode that is set to be positive relative to the current in the path of the current from the second voltage conversion circuit to the second line filter circuit.

[0025] According to this structure, when the multi-output power supply operates in the first mode, the voltage required for current to flow through the path from the second voltage conversion circuit to the second line filter circuit is higher than the voltage required for current to flow through the path from the second voltage conversion circuit to the first line filter circuit by an amount corresponding to the forward voltage of the diode. Therefore, according to this structure, the diode can be used to substantially cut off the former path only when the multi-output power supply operates in the first mode.

[0026] The first DC-DC conversion circuit of the aforementioned multi-output power supply device preferably also includes a power factor improvement circuit.

[0027] According to this structure, in the first DC circuit, AC power supplied from the AC power source can be utilized more effectively.

[0028] Furthermore, the aforementioned multi-output power supply device may have the following structure: it further includes a third power supply unit that outputs a third DC voltage in both the first and second modes. The third power supply unit includes: a third line filter circuit connected to an AC power source; a third DC conversion circuit that converts the AC voltage output by the third line filter circuit into DC voltage, including a diode bridge circuit; a third voltage conversion circuit that converts the DC voltage output by the third DC conversion circuit into a third DC voltage; and a current control unit for the third power supply unit, which is provided on the current path from the third voltage conversion circuit to the third line filter circuit. The multi-output power supply device also includes a third power supply unit interconnection line that interconnects the outputs of the first and third DC conversion circuits. The DC voltage output by the first DC conversion circuit in the first mode is higher than the DC voltage output by the third DC conversion circuit. The current control unit for the third power supply unit is configured to be non-conducting in the first mode and conducting in the second mode.

[0029] According to this structure, it is possible to output the first DC voltage, the second DC voltage, and the third DC voltage while achieving current balance in the first line filter circuit, the second line filter circuit, and the third line filter circuit.

[0030] Invention Effects

[0031] According to the present invention, a multi-output power supply device is provided in which the current does not become unbalanced in the line filter circuits included in each of the multiple power supply sections. Attached Figure Description

[0032] Figure 1 This is a circuit diagram of a multi-output power supply device according to a first embodiment of the present invention.

[0033] Figure 2 To show Figure 1 The waveform diagram shows the conducted noise characteristics of the multi-output power supply device.

[0034] Figure 3 This is a circuit diagram of a multi-output power supply device according to a second embodiment of the present invention.

[0035] Figure 4 This is a circuit diagram of a multi-output power supply device according to the third embodiment of the present invention.

[0036] Figure 5 This is a circuit diagram for a conventional multi-output power supply device.

[0037] Figure 6 This is a circuit diagram of a multi-output power supply device conceived by the inventors during the process of completing this invention.

[0038] Figure 7 To show Figure 6 The waveform diagram shows the conducted noise characteristics of the multi-output power supply device.

[0039] Figure Labels

[0040] 10A, 10B, 10C: Multi-output power supply unit; 11: First switch; 12: High-potential side interconnection line for the second power supply section; 13: Low-potential side interconnection line for the second power supply section; 14: First diode; 15: High-potential side interconnection line for the third power supply section; 16: Low-potential side interconnection line for the third power supply section; 17: Third diode; 20: First power supply section; 21: First line filter circuit; 22: First diode bridge circuit; 23: Power factor improvement circuit; 24: First voltage conversion circuit; 25: First high-potential side DC line; 26: First low-potential side DC line; 27: First smoothing capacitor; 30A, 30B: Second power supply section; 31: Second line filter circuit; 32: Second diode bridge circuit; 34: Second voltage conversion circuit; 35: Second high-potential side DC line; 36: Second low-potential side DC line; 37: Second smoothing capacitor; 38: Second switch; 39: Second diode; 40: Third power supply section; 41: Third line filter circuit; 42: Third diode bridge circuit; 44: Third voltage conversion circuit; 45: Third high-potential side DC line; 46: Third low-potential side DC line; 47: Third smoothing capacitor; 48: Third switch. Detailed Implementation

[0041] The following description, with reference to the accompanying drawings, illustrates embodiments of the multi-output power supply device of the present invention.

[0042] [First Embodiment]

[0043] Figure 1 The figure shows a multi-output power supply device 10A according to a first embodiment of the present invention. As shown in the figure, the multi-output power supply device 10A includes: a first switch 11; a first power supply unit 20 connected to an AC power supply G, such as a commercial AC power supply, via the first switch 11; and a second power supply unit 30A directly connected to the AC power supply G without via the first switch 11.

[0044] The first switch 11 is configured to be in an open or closed state according to an external signal S1. In this embodiment, the external signal S1 is a signal output by the upper-level control circuit. When the upper-level control circuit operates the multi-output power supply device 10A in the first mode, it outputs the external signal S1 to close the first switch 11. Accordingly, the first power supply unit 20 is connected to the AC power supply G. On the other hand, when the upper-level control circuit operates the multi-output power supply device 10A in the second mode, it outputs the external signal S1 to open the first switch 11. Accordingly, the first power supply unit 20 is disconnected from the AC power supply G.

[0045] When the first switch 11 is closed, the first power supply unit 20 outputs 24 [V] equivalent to the "first DC voltage" of the present invention to the load circuit (not shown). Figure 1As shown, the first power supply unit 20 includes: a first line filter circuit 21, one end of which is connected to the AC power supply G via a first switch 11; a first diode bridge circuit 22, the AC terminal of which is connected to the other end of the first line filter circuit 21; a power factor improvement circuit 23, the input terminal of which is connected to the DC terminal of the first diode bridge circuit 22; a first voltage conversion circuit 24, which is connected to the output terminal of the power factor improvement circuit 23 via a first high-potential side DC line 25 and a first low-potential side DC line 26; and a first smoothing capacitor 27, which is connected between the lines of the first high-potential side DC line 25 and the first low-potential side DC line 26.

[0046] The first diode bridge circuit 22, the power factor improvement circuit 23, and the first smoothing capacitor 27 constitute the "first DC conversion circuit" of the present invention. The first DC conversion circuits 22, 23, and 27 convert the AC voltage output from the first line filter circuit 21 into DC voltage and supply it to the first voltage conversion circuit 24. In this embodiment, the DC converted voltage (i.e., the potential of the first high-potential side DC line 25 based on the potential of the first low-potential side DC line 26) is set to 400 [V].

[0047] The first voltage conversion circuit 24 is a chopper circuit that steps down the aforementioned 400 [V] to 24 [V]. The first voltage conversion circuit 24 outputs the stepped-down 24 [V] to a load circuit (not shown).

[0048] Regardless of the state of the first switch 11, the second power supply unit 30A outputs 5V, equivalent to the "second DC voltage" of the present invention, to the load circuit (not shown). Figure 1 As shown, the second power supply unit 30A includes: a second line filter circuit 31, one end of which is connected to the AC power supply G; a second diode bridge circuit 32, the AC terminal of which is connected to the other end of the second line filter circuit 31; a second voltage conversion circuit 34, which is connected to the DC terminal of the second diode bridge circuit 32 via a second high-potential side DC line 35 and a second low-potential side DC line 36; a second smoothing capacitor 37, which is connected between the lines of the second high-potential side DC line 35 and the second low-potential side DC line 36; and a second switch 38, which is disposed on the second low-potential side DC line 36.

[0049] The second diode bridge circuit 32 and the second smoothing capacitor 37 constitute the "second DC conversion circuit" of the present invention. The second DC conversion circuits 32 and 37 convert the AC voltage output from the second line filter circuit 31 into DC voltage and supply it to the second voltage conversion circuit 34. In this embodiment, the DC converted voltage (i.e., the potential of the second high-potential side DC line 35 based on the potential of the second low-potential side DC line 36) is set to a voltage much lower than 400 [V].

[0050] The second voltage conversion circuit 34 is a chopper circuit that steps down or boosts the DC voltage supplied by the second DC conversion circuits 32 and 37 to 5V. The second voltage conversion circuit 34 outputs the stepped-down or boosted 5V to a load circuit (not shown).

[0051] The second switch 38 corresponds to the "current control unit for the second power supply section" of the present invention, and is configured to be in an open or closed state according to the external signal S2. In this embodiment, the external signal S2 is a signal output by the upper-level control circuit. When the upper-level control circuit operates the multi-output power supply device 10A in the first mode, it outputs the external signal S2 to open the second switch 38. Accordingly, the current path (second low-potential side DC line 36) from the second voltage conversion circuit 34 to the second line filter circuit 31 is cut off. On the other hand, when the upper-level control circuit operates the multi-output power supply device 10A in the second mode, it outputs the external signal S2 to close the second switch 38. Accordingly, the current path (second low-potential side DC line 36) from the second voltage conversion circuit 34 to the second line filter circuit 31 is established.

[0052] In this way, in mode 1, switch 11 is closed and switch 38 is open, and the multi-output power supply 10A outputs both 24V and 5V. In mode 2, switch 11 is open and switch 38 is closed, and the multi-output power supply 10A outputs only 5V. Alternatively, it can be said that the multi-output power supply 10A is in operation when operating in mode 1 and in standby mode when operating in mode 2.

[0053] The multi-output power supply device 10A further includes: a high-potential side interconnection line 12 for the second power supply section, connecting the first high-potential side DC line 25 and the second high-potential side DC line 35; a low-potential side interconnection line 13 for the second power supply section, connecting the first low-potential side DC line 26 and the second low-potential side DC line 36; and a first diode 14 disposed on the high-potential side interconnection line 12 for the second power supply section. The first diode 14 has an anode facing the first power supply section 20 (the first high-potential side DC line 25) and a cathode facing the second power supply section 30A (the second high-potential side DC line 35). The high-potential side interconnection line 12 for the second power supply section, the low-potential side interconnection line 13 for the second power supply section, and the first diode 14 correspond to the "interconnection line for the second power supply section" of the present invention.

[0054] As described above, when the multi-output power supply device 10A is in operation (first switch 11: closed, second switch 38: open), the voltage supplied by the second DC-DC conversion circuits 32 and 37 of the second power supply unit 30A is much lower than the voltage supplied by the first DC-DC conversion circuits 22, 23, and 27 of the first power supply unit 20 (400 [V]). Therefore, the voltage appearing between the lines of the second high-potential side DC line 35 and the second low-potential side DC line 36 is the value obtained by subtracting the forward voltage of the first diode 14 (approximately 0.7 [V]) from 400 [V]. At this time, the first diode 14 supplies current to the second voltage conversion circuit 34 instead of the second diode bridge circuit 32. In this case, the second voltage conversion circuit 34 does not reduce the DC voltage supplied by the second DC-DC conversion circuits 32 and 37 to 5 [V] instead of the 400 [V] - approximately 0.7 [V] DC voltage supplied by the first diode 14.

[0055] On the other hand, when the multi-output power supply device 10A is in standby mode (first switch 11: open circuit, second switch 38: closed circuit), the voltage supplied by the second DC-DC conversion circuits 32 and 37 of the second power supply unit 30A is higher than the voltage supplied by the first DC-DC conversion circuits 22, 23, and 27 of the first power supply unit 20 (0 [V]). Therefore, the voltage appearing between the second high-potential side DC line 35 and the second low-potential side DC line 36 is equal to the voltage supplied by the second DC-DC conversion circuits 32 and 37 to the second voltage conversion circuit 34. At this time, the first diode 14 does not supply current to the second voltage conversion circuit 34.

[0056] When the multi-output power supply device 10A is in operation, and assuming the current flowing from the first power supply unit 20 to the load circuit (not shown) is Ia and the current flowing from the second power supply unit 30A to the load circuit (not shown) is Ib, the currents flowing in each part are as follows.

[0057] • The current flowing from left to right in the first line filter circuit 21 is: Ia + Ib

[0058] • The current flowing from right to left in the first line filter circuit 21 is: Ia + Ib

[0059] • The current flowing from left to right in the second line filter circuit 31: 0

[0060] • The current flowing from right to left in the second line filter circuit 31: 0

[0061] • The current flowing downwards from the high-potential side interconnection line 12 in the second power supply section, as shown in the diagram: Ib

[0062] • The current flowing upwards from the bottom of the diagram via the low-potential interconnection line 13 in the second power supply section: Ib

[0063] In the first line filter circuit 21, the current flowing from left to right and the current flowing from right to left are both Ia + Ib, achieving a balance. Similarly, in the second line filter circuit 31, the current flowing from left to right and the current flowing from right to left are both 0, also achieving a balance. This is because the second switch 38, which is in an open-circuit state during operation, cuts off the current path from the second voltage conversion circuit 34 to the second line filter circuit 31.

[0064] Figure 2 The conducted noise characteristics of the multi-output power supply unit 10A in operation are shown. Waveform W1 is the quasi-peak value (QP value) obtained by measurement, and waveform W2 is the average value (AV value) obtained by measurement. Additionally, line L1 represents the limit value of QP as specified by a standard (e.g., VCCI Class B), and line L2 represents the limit value of AV as specified by a standard (e.g., VCCI Class B). This figure shows that the result of the first line filter circuit 21 and the second line filter circuit 31 fully performing their filtering functions is that the QP value and AV value converge to levels below the limit values.

[0065] [Second Embodiment]

[0066] Figure 3 The figure shows a multi-output power supply device 10B according to a second embodiment of the present invention. As shown in the figure, the multi-output power supply device 10B differs from the multi-output power supply device 10A in that it has a second power supply unit 30B instead of a second power supply unit 30A, but is otherwise the same, for example, it outputs both 24 [V] and 5 [V] in the first mode, and only outputs 5 [V] in the second mode.

[0067] The second power supply unit 30B includes: a second line filter circuit 31, one end of which is connected to the AC power supply G; a second diode bridge circuit 32, the AC terminal of which is connected to the other end of the second line filter circuit 31; a second voltage conversion circuit 34, which is connected to the DC terminal of the second diode bridge circuit 32 via a second high-potential side DC line 35 and a second low-potential side DC line 36; a second smoothing capacitor 37, which is connected between the lines of the second high-potential side DC line 35 and the second low-potential side DC line 36; and a second diode 39, which is disposed on the second low-potential side DC line 36.

[0068] The second diode 39 corresponds to the "current control unit for the second power supply section" of the present invention, and has an anode connected to the second voltage conversion circuit 34 and a cathode connected to the second diode bridge circuit 32.

[0069] In the path of current from the second voltage conversion circuit 34 to the AC power supply G, there are two paths: the second low-potential side DC line 36 → the second power supply section low-potential side interconnection line 13 → the first low-potential side DC line 26 → the power factor improvement circuit 23 → the first diode bridge circuit 22 → the first line filter circuit 21 → the first switch 11 (hereinafter referred to as the "first path") and the second low-potential side DC line 36 (second diode 39) → the second diode bridge circuit 32 → the second line filter circuit 31 (hereinafter referred to as the "second path").

[0070] The first path is valid only when the first switch 11 is closed, i.e., when the multi-output power supply device 10B is in operation. In other words, the current from the second voltage conversion circuit 34 to the AC power supply G cannot pass through the first path when the multi-output power supply device 10B is in standby mode. Therefore, the current from the second voltage conversion circuit 34 to the AC power supply G passes through the second path when the multi-output power supply device 10B is in standby mode.

[0071] On the other hand, when the multi-output power supply device 10B is in operation, the current from the second voltage conversion circuit 34 to the AC power supply G flows through the first path. This is because the only forward diode present in the first path is diode 22a, which constitutes the first diode bridge circuit 22. In contrast, there are two forward diodes in the second path (second diode 39 and diode 32a, which constitutes the second diode bridge circuit 32), and the total forward voltage in the first path (approximately 0.7 [V]) is less than the total forward voltage in the second path (approximately 1.4 [V]).

[0072] When the multi-output power supply device 10B is in operation, and assuming the current flowing from the first power supply unit 20 to the load circuit (not shown) is Ia and the current flowing from the second power supply unit 30B to the load circuit (not shown) is Ib, the currents flowing in each part are as follows.

[0073] • The current flowing from left to right in the first line filter circuit 21 is: Ia + Ib

[0074] • The current flowing from right to left in the first line filter circuit 21 is: Ia + Ib

[0075] • The current flowing from left to right in the second line filter circuit 31: 0

[0076] • The current flowing from right to left in the second line filter circuit 31: 0

[0077] • The current flowing downwards from the high-potential side interconnection line 12 in the second power supply section, as shown in the diagram: Ib

[0078] • The current flowing upwards from the bottom of the diagram via the low-potential interconnection line 13 in the second power supply section: Ib

[0079] In the first line filter circuit 21, the current flowing from left to right and the current flowing from right to left are both Ia + Ib, achieving a balance. Similarly, in the second line filter circuit 31, the current flowing from left to right and the current flowing from right to left are both 0, also achieving a balance. This is because the second diode 39, which generates a positive voltage, cuts off the current path from the second voltage conversion circuit 34 to the second line filter circuit 31, i.e., the second path.

[0080] Conducted noise characteristics of the multi-output power supply unit 10B in operation and Figure 2 The conducted noise characteristics of the multi-output power supply device 10A shown are the same.

[0081] [Embodiment 3]

[0082] Figure 4 The multi-output power supply device 10C according to the third embodiment of the present invention is shown. As shown in the figure, the multi-output power supply device 10C differs from the multi-output power supply device 10A in that it also includes a third power supply unit 40 that outputs 12 [V] equivalent to the "third DC voltage" of the present invention in both the first mode and the second mode, and also includes a high-potential side interconnection line 15 for the third power supply unit, a low-potential side interconnection line 16 for the third power supply unit, and a third diode 17 constituting the "interconnection line for the third power supply unit" of the present invention. In other respects, it is the same, for example, the first power supply unit 20 outputs 24 [V] only in the first mode, and the second power supply unit 30A outputs 5 [V] in both the first mode and the second mode.

[0083] The third power supply unit 40 includes: a third line filter circuit 41, one end of which is connected to the AC power supply G; a third diode bridge circuit 42, the AC terminal of which is connected to the other end of the third line filter circuit 41; a third voltage conversion circuit 44, which is connected to the DC terminal of the third diode bridge circuit 42 via a third high-potential side DC line 45 and a third low-potential side DC line 46; a third smoothing capacitor 47, which is connected between the lines of the third high-potential side DC line 45 and the third low-potential side DC line 46; and a third switch 48, which is disposed on the third low-potential side DC line 46.

[0084] The third diode bridge circuit 42 and the third smoothing capacitor 47 constitute the "third DC conversion circuit" of the present invention. The third DC conversion circuits 42 and 47 convert the AC voltage output from the third line filter circuit 41 into DC voltage and supply it to the third voltage conversion circuit 44. In this embodiment, the DC converted voltage (i.e., the potential of the third high-potential side DC line 45 based on the potential of the third low-potential side DC line 46) is set to a voltage much lower than 400 [V].

[0085] The third voltage conversion circuit 44 is a chopper circuit that steps down or boosts the DC voltage supplied by the third DC conversion circuits 42 and 47 to 12 [V]. The third voltage conversion circuit 44 outputs the stepped-down or boosted 12 [V] to a load circuit (not shown).

[0086] The third switch 48 corresponds to the "current control unit for the third power supply section" of the present invention, and is configured to be in an open or closed state according to the external signal S3. In this embodiment, the external signal S3 is a signal output by the upper-level control circuit. When the upper-level control circuit operates the multi-output power supply device 10C in the first mode, it outputs the external signal S3 to open the third switch 48. Accordingly, the current path (the third low-potential side DC line 46) from the third voltage conversion circuit 44 to the third line filter circuit 41 is cut off. On the other hand, when the upper-level control circuit operates the multi-output power supply device 10C in the second mode, it outputs the external signal S3 to close the third switch 48. Accordingly, the current path (the second low-potential side DC line 36) from the third voltage conversion circuit 44 to the third line filter circuit 41 is established.

[0087] The third power supply unit connects the first high-potential side DC line 25 and the third high-potential side DC line 45 via a high-potential side interconnection line 15. The third power supply unit connects the first low-potential side DC line 26 and the third low-potential side DC line 46 via a low-potential side interconnection line 16. The third diode 17 is disposed on the high-potential side interconnection line 15 of the third power supply unit and has an anode facing the first power supply unit 20 (first high-potential side DC line 25) and a cathode facing the third power supply unit 40 (third high-potential side DC line 45).

[0088] When the multi-output power supply device 10C operates in the first mode (first switch 11: closed, second switch 38: open, third switch 48: open), the voltage supplied by the third DC-DC conversion circuits 42 and 47 of the third power supply unit 40 is much lower than the voltage supplied by the first DC-DC conversion circuits 22, 23, and 27 of the first power supply unit 20 (400 [V]). Therefore, the voltage appearing between the third high-potential side DC line 45 and the third low-potential side DC line 46 is the value obtained by subtracting the forward voltage of the third diode 17 (approximately 0.7 [V]) from 400 [V]. At this time, the third diode 17 supplies current to the third voltage conversion circuit 44 instead of the third diode bridge circuit 42. In this case, the third voltage conversion circuit 44 does not reduce the DC voltage supplied by the third DC-DC conversion circuits 42 and 47 to 12 [V] instead of the 400 [V] - approximately 0.7 [V] DC voltage supplied by the third diode 17.

[0089] On the other hand, when the multi-output power supply device 10C operates in the second mode (first switch 11: open circuit, second switch 38: closed circuit, third switch 48: closed circuit), the voltage supplied by the third DC-DC conversion circuits 42 and 47 of the third power supply unit 40 is higher than the voltage supplied by the first DC-DC conversion circuits 22, 23, and 27 of the first power supply unit 20 (0 [V]). Therefore, the voltage appearing between the third high-potential side DC line 45 and the third low-potential side DC line 46 is equal to the voltage supplied by the third DC-DC conversion circuits 42 and 47 to the third voltage conversion circuit 44. At this time, the third diode 17 does not supply current to the third voltage conversion circuit 44.

[0090] The multi-output power supply device 10C according to this embodiment can output three different voltages (24V, 12V, and 5V) while maintaining the current balance in the first line filter circuit 21, the second line filter circuit 31, and the third line filter circuit 41. Furthermore, if an imbalance occurs in the current in the second line filter circuit 31 and the third line filter circuit 41 during operation in the second mode, it is sufficient to open either the second switch 38 or the third switch 48.

[0091] The first, second, and third embodiments of the multi-output power supply device of the present invention have been described above, but the structure of the present invention is not limited to these.

[0092] For example, the first DC voltage output by the first power supply unit 20 can be a DC voltage other than 24 [V]. Similarly, the second DC voltage output by the second power supply units 30A and 30B can be a DC voltage other than 5 [V], and the third DC voltage output by the third power supply unit 40 can be a DC voltage other than 12 [V] (for example, a voltage equal to the second DC voltage).

[0093] In addition, the external signal S1 controlling the first switch 11, the external signal S2 controlling the second switch 38, and the external signal S3 controlling the third switch 48 can be the same signal.

[0094] In addition, in the third embodiment, a power supply unit similar to the second power supply unit 30A is used as the third power supply unit 40, but the third power supply unit 40 may also be a power supply unit similar to the second power supply unit 30B.

[0095] Furthermore, the multi-output power supply device of the present invention may also include four or more power supply units. In this case, the additional power supply unit may be either a power supply unit similar to the second power supply unit 30A or a power supply unit similar to the second power supply unit 30B.

Claims

1. A multiple output power supply device having a first power supply section that outputs a first DC voltage and a second power supply section that outputs a second DC voltage, and capable of operating in a first mode in which both the first DC voltage and the second DC voltage are output and a second mode in which only the second DC voltage is output, characterized by: a first line filter circuit connected to an AC power supply via a first switch; a first DC conversion circuit that DC-converts an AC voltage output from the first line filter circuit, including a diode bridge circuit; and a first voltage conversion circuit that converts a DC voltage output from the first DC conversion circuit into the first DC voltage, the second power supply section including: a second line filter circuit connected to the AC power supply; a second DC conversion circuit that DC-converts an AC voltage output from the second line filter circuit, including a diode bridge circuit; a second voltage conversion circuit that converts a DC voltage output from the second DC conversion circuit into the second DC voltage; and a second power supply section current control unit provided in a current path from the second voltage conversion circuit to the second line filter circuit, the multiple output power supply device further characterized by: a second power supply section interconnection line that interconnects outputs of the first DC conversion circuit and the second DC conversion circuit to each other, the first DC conversion circuit outputting a DC voltage that is higher than a DC voltage output by the second DC conversion circuit in the first mode, the first switch being configured to be in a closed state in the first mode and in an open state in the second mode, and the second power supply section current control unit being configured to be non-conductive in the first mode and conductive in the second mode. The first power supply section includes:

2. The multiple output power supply device according to claim 1, characterized in that the second power supply section current control unit is a second switch configured to be in an open state in the first mode and in a closed state in the second mode.

3. The multiple output power supply device according to claim 2, characterized in that the first switch and the second switch are in an open state or a closed state in accordance with the same or different external signals.

4. The multiple output power supply device according to claim 1, characterized in that the second power supply section current control unit is a diode provided in a forward direction with respect to a current in a current path from the second voltage conversion circuit to the second line filter circuit.

5. The multiple output power supply device according to any one of claims 1 to 4, characterized in that the first DC conversion circuit further includes a power factor improvement circuit.

6. The multiple output power supply device according to any one of claims 1 to 4, characterized by further including a third power supply section that outputs a third DC voltage in both the first mode and the second mode. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The third power supply section includes a third line filter circuit connected to the alternating current power supply, a third DC conversion circuit that DC-converts alternating current voltage output from the third line filter circuit, including a diode bridge circuit, a third voltage conversion circuit that converts DC voltage output from the third DC conversion circuit into the third DC voltage, and a third power supply section current control unit provided on a path of current from the third voltage conversion circuit to the third line filter circuit, The third power supply section further includes a third power supply section interconnection line that interconnects outputs of the first DC conversion circuit and the third DC conversion circuit to each other, The DC voltage output from the first DC conversion circuit in the first mode is higher than the DC voltage output from the third DC conversion circuit, The third power supply section current control unit is configured to be non-conductive in the first mode and conductive in the second mode.

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