DC power supply circuit

Abstract

To provide a DC power supply circuit in which power imbalance between voltage conversion circuits connected to respective multiple voltage sources is controlled to output a desired DC power.SOLUTION: A DC power supply circuit of an embodiment comprises a first voltage adjustment circuit that adjusts a voltage value of a DC voltage output from a corresponding external voltage source to a first predetermined voltage value and outputs the adjusted voltage value, a second voltage adjustment circuit that adjusts the voltage value of the DC voltage output from the first voltage adjustment circuit to a second predetermined voltage value and outputs the voltage value, an inverter circuit that converts the DC voltage output from the second voltage adjustment circuit into an AC voltage, n (n: an integer of 2 or greater) voltage conversion circuits including a transformer for isolating and transmitting the AC voltage output from the inverter circuit and a rectifier circuit for rectifying the output voltage of the transformer and converting the same into a DC voltage, and an external output voltage detection circuit that detects the voltage between the n voltage conversion circuits and a load as an external output voltage. The DC power supply circuit generates an external output voltage in which the DC voltages output from the n voltage conversion circuits are combined by connecting the output terminals of the rectifier circuits of the n voltage conversion circuits in series.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a DC power supply circuit. [Background technology]

[0002] 2. Description of the Related Art DC power supply devices that have a plurality of inputs and supply DC power to a load are known. As such a DC power supply device, for example, a circuit configuration has been proposed in which, in order to receive power from two independent voltage sources and output the power to a load, a voltage conversion circuit is connected to each voltage source, and the voltage sources are connected in parallel on the secondary side to output DC power with a predetermined output voltage.

[0003] In this case, the voltage conversion circuit included a feedback circuit for controlling the output voltage, a chopper for receiving a feedback signal and controlling the voltage, an inverter circuit and a transformer for insulating the primary and secondary sides, and a rectifier circuit for smoothing the output from the transformer.

[0004] Also, as a DC power supply device, a DC power supply device using a series resonant converter is known, which is capable of outputting a large amount of power. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-236531 A Summary of the Invention [Problem to be solved by the invention]

[0006] In conventional DC power supply devices that aim to achieve high output by receiving power from multiple voltage sources and outputting voltage to a load, there was a possibility that power imbalance would occur in the voltage conversion circuits connected to each voltage source due to voltage differences between the input voltage sources or variations in circuit constants.

[0007] The present invention has been made in consideration of the above, and aims to provide a DC power supply circuit that can suppress power imbalance between voltage conversion circuits connected to each of a plurality of voltage sources and output a desired DC power. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, a DC power supply circuit of an embodiment is a DC power supply circuit that converts a voltage value of an input DC voltage to a predetermined voltage value and outputs the voltage value to a load, the DC power supply circuit including: a first voltage adjustment circuit that adjusts a voltage value of a DC voltage output from a corresponding external voltage source to a first predetermined voltage value and outputs the voltage value; a second voltage adjustment circuit that adjusts a voltage value of the DC voltage output from the first voltage adjustment circuit to a second predetermined voltage value and outputs the voltage value; an inverter circuit that converts the DC voltage output from the second voltage adjustment circuit to an AC voltage; a transformer for insulating and transmitting the AC voltage output from the inverter circuit; and an external output voltage detection circuit that detects a voltage between the n voltage conversion circuits and the load as the external output voltage, the DC power supply circuit being configured to generate the external output voltage obtained by combining the DC voltages output from the n voltage conversion circuits by connecting output terminals of the rectification circuits of the n voltage conversion circuits in series; The second voltage adjustment circuit of each of the n voltage conversion circuits receives the voltage value of the external output voltage detected by the external output voltage detection circuit, and adjusts the voltage value of the DC voltage output from the first voltage adjustment circuit based on the voltage value so that it becomes the second predetermined voltage value, and outputs the adjusted voltage. Effect of the Invention

[0009] According to the present invention, the voltage and current applied to each inverter circuit are equalized, improving the power balance of each voltage conversion circuit, which is expected to lead to improved power efficiency and a more compact power supply. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating the principle of the embodiment. [Diagram 2] FIG. 2 is an explanatory diagram of a specific circuit example of the first embodiment. [Diagram 3] FIG. 3 is an explanatory diagram of a comparative example. [Figure 4] FIG. 4 is an explanatory diagram (part 1) of the results of an operational simulation of the comparative example. [Diagram 5] FIG. 5 is a diagram (part 2) illustrating the results of an operational simulation of the comparative example. [Figure 6] FIG. 6 is an explanatory diagram (part 3) of the operation simulation result of the comparative example. [Figure 7] FIG. 7 is a diagram (part 1) illustrating the results of an operational simulation of the embodiment. [Figure 8] FIG. 8 is a diagram (part 2) illustrating the results of an operational simulation of the embodiment. [Figure 9] FIG. 9 is a diagram (part 3) for explaining the results of an operational simulation of the embodiment. [Figure 10] FIG. 10 is an explanatory diagram of a specific circuit example of a modified example of the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Next, an embodiment will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating the principle of the embodiment. The DC power supply device 10 of the embodiment includes a first voltage source 11, a first input chopper 12, a first voltage detector 13, a first output chopper 14, a first inverter 15, a first transformer 16, a first rectifier circuit 17, a second voltage source 18, a second input chopper 19, a second voltage detector 20, a second output chopper 21, a second inverter 22, a second transformer 23, a second rectifier circuit 24, a voltage / current detector 26, and a control circuit 27.

[0012] In the above configuration, the first input chopper 12, the first voltage detector 13, the first output chopper 14, the first inverter 15, the first transformer 16 and the first rectifier circuit 17 configure a first voltage conversion circuit.

[0013] Moreover, the second input chopper 19, the second voltage detector 20, the second output chopper 21, the second inverter 22, the second transformer 23 and the second rectifier circuit 24 configure a second voltage conversion circuit.

[0014] In addition, the first voltage conversion circuit and the second voltage conversion circuit have the same configuration. For example, the first input chopper 12 and the second input chopper 19 have the same configuration.

[0015] A first voltage source 11 outputs DC power having a first voltage to a first input chopper 12 . The first voltage source 11 is an example of an external voltage source in the first voltage conversion circuit.

[0016] The first input chopper 12 functions as a first voltage adjustment circuit in the first voltage conversion circuit, and outputs the voltage of the input DC power to the first output chopper 14 as a first predetermined voltage value based on the detection result of the first voltage detector 13. The first input chopper 12 may be a step-up chopper, a step-down chopper, or a step-up / step-down chopper.

[0017] The first voltage detector 13 functions as a voltage detection circuit in the first voltage conversion circuit, detects the output voltage of the first input chopper 12 , and outputs it to the first input chopper 12 .

[0018] The first output chopper 14 functions as a second voltage adjustment circuit in the first voltage conversion circuit, and outputs the voltage of the input DC power to the first inverter 15 as a second predetermined voltage value based on the voltage detection result of the voltage / current detector 26. The first output chopper 14 may be a step-up chopper, a step-down chopper, or a step-up / step-down chopper.

[0019] The first inverter 15 functions as an inverter circuit in the first voltage conversion circuit, performs DC / AC conversion of the input DC power, and outputs the converted power to the first transformer 16 .

[0020] The first transformer 16 functions as a transformer in the first voltage conversion circuit, and transforms the input AC power at a predetermined transformation ratio (winding ratio between the primary coil and the secondary coil) and outputs the transformed power to the first rectifier circuit 17.

[0021] The first rectifier circuit 17 functions as a rectifier circuit in the first voltage conversion circuit, rectifies the input AC power, and outputs the rectified AC power to the output terminal via the voltage / current detector 26 as DC power.

[0022] The second voltage source 18 outputs DC power having a second voltage to a second input chopper 19 . The second voltage source 18 is an example of an external voltage source in the second voltage conversion circuit.

[0023] The second input chopper 19 functions as a first voltage adjustment circuit in the second voltage conversion circuit, and outputs the voltage of the input DC power to the second output chopper 21 as a second predetermined voltage value based on the detection result of the second voltage detector 20. The second input chopper 19 may be a step-up chopper, a step-down chopper, or a step-up / step-down chopper.

[0024] The second voltage detector 20 functions as a voltage detection circuit in the second voltage conversion circuit, detects the output voltage of the second input chopper 19 , and outputs it to the second input chopper 19 .

[0025] The second output chopper 21 functions as a second voltage adjustment circuit in the second voltage conversion circuit, and outputs the voltage of the input DC power to the second inverter 22 as a second predetermined voltage value based on the voltage detection result of the voltage / current detector 26. The second output chopper 21 may be a step-up chopper, a step-down chopper, or a step-up / step-down chopper.

[0026] The second inverter 22 functions as an inverter circuit in the second voltage conversion circuit, performs DC / AC conversion of the input DC power, and outputs the converted power to the second transformer 23.

[0027] The second transformer 23 functions as a transformer in the second voltage conversion circuit, and transforms the input AC power at a predetermined transformation ratio (winding ratio between the primary coil and the secondary coil) and outputs the transformed power to the second rectifier circuit 24.

[0028] The second rectifier circuit 24 functions as a rectifier circuit in the second voltage conversion circuit, is connected in series to the first rectifier circuit 17, and rectifies the input AC power and outputs it as DC power to the output terminal via the first rectifier circuit 17 and the voltage / current detector 26.

[0029] The voltage / current detector 26 functions as an external output voltage detection circuit, detects the voltage and current of the power obtained by superimposing the DC power of the second rectifier circuit 24 on the DC power of the first rectifier circuit 17, and outputs a voltage detection signal to the first output chopper 14 and the second output chopper 21 as a feedback signal. The detection signals of the external output voltage and current detected by the voltage / current detector 26 can be output to the outside, so that the voltage value and current value can be used for monitoring.

[0030] The control circuit 27 controls the first input chopper 12, the first output chopper 14, the first inverter 15, the second input chopper 19, the second output chopper 21 and the second inverter 22 based on the outputs of the first voltage detector 13, the second voltage detector 20 and the voltage / current detector 26.

[0031] As described above, the first voltage adjustment circuit, the second voltage adjustment circuit, the inverter circuit, the transformer and the rectifier circuit included in each voltage conversion circuit have the same configuration in all voltage conversion circuits, so that the power balance of each voltage conversion circuit can be improved.

[0032] Furthermore, first voltage source 11 and second voltage source 18, which function as DC voltage sources, are different voltage sources, so that a large output can be easily achieved.

[0033] Here, an outline of the operation of the embodiment will be described. First, the operation of first voltage source 11 to first transformer 16 will be described. The first voltage source 11 functions as a DC voltage source, and outputs DC power having a first voltage Vdc1 to the first input chopper 12.

[0034] In parallel with this, the first voltage detector 13 detects the output voltage Vdc 1 of the first input chopper 12 and outputs it to the first input chopper 12 . As a result, the first input chopper 12, as a first voltage adjustment circuit, adjusts the voltage Vdc1 of the input DC power to a first predetermined voltage value = Vdct1 based on the detection result of the first voltage detector 13, and outputs it to the first output chopper 14.

[0035] The first output chopper 14 serves as a second voltage adjustment circuit and outputs the voltage of the input DC power to the first inverter 15 as a second predetermined voltage value Vdct11 based on the output voltage Vout, which is the voltage detection result of the voltage / current detector 26. The first inverter 15 performs DC / AC conversion of the input DC power and outputs the converted power to the first transformer 16 .

[0036] The first transformer 16 transforms the input AC power at a predetermined transformation ratio and outputs the transformed AC power to the first rectifier circuit 17 .

[0037] Next, the operation of second voltage source 18 to second transformer 23 will be described. The second voltage source 18 functions as a DC voltage source and outputs DC power having a second voltage Vdc2 to the second input chopper 19.

[0038] In parallel with this, the second voltage detector 20 detects the output voltage Vdc 2 of the second input chopper 19 and outputs it to the second input chopper 19 . Thereby, the second input chopper 19 serves as a first voltage adjustment circuit and outputs the voltage of the input DC power as a second predetermined voltage value based on the detection result of the second voltage detector 20 to the second output chopper 21 .

[0039] The second output chopper 21 serves as a second voltage adjustment circuit and outputs the voltage of the input DC power to the second inverter 22 as a second predetermined voltage value based on the output voltage Vout, which is the voltage detection result of the voltage / current detector 26. The second inverter 22 functions as an inverter circuit under the control of the control circuit 27, performs DC / AC conversion of the input DC power, and outputs the converted power to the second transformer .

[0040] The second transformer 23 transforms the input AC power at a predetermined transformation ratio and outputs the transformed AC power to the second rectifier circuit 24 .

[0041] As a result, the first rectifier circuit 17 rectifies the AC power that has been transformed by the first transformer 16 and input, and outputs the rectified AC power to the output terminal as DC power. In addition, the second rectifier circuit 24 rectifies the input AC power transformed by the second transformer 23, superimposes it on the DC power output by the first rectifier circuit 17, and outputs it to the output terminal via the first rectifier circuit 17.

[0042] At this time, the voltage / current detector 26 detects the voltage of the power obtained by superimposing the DC power of the second rectifier circuit 24 on the DC power of the first rectifier circuit 17, and outputs a voltage detection signal to the first output chopper 14 and the second output chopper 21 as a feedback signal. Therefore, ultimately, the voltage of the power obtained by superimposing the DC power of the second rectifier circuit 24 on the DC power of the first rectifier circuit 17 becomes the desired voltage.

[0043] As described above, the first voltage source 11, the first input chopper 12 and the first voltage detector 13 function as virtual voltage sources, and the second voltage source 18, the second input chopper 19 and the second voltage detector 20 function as virtual voltage sources, so that the virtual first voltage source and the virtual second voltage source effectively operate as ideal voltage sources that output the same voltage.

[0044] As a result, the power from the first voltage source 11 and the second voltage source 18 that is effectively processed by the voltage conversion circuit is controlled to an ideal desired voltage. This allows the input voltage of the first output chopper 14 and the input voltage of the second output chopper 19 to be the same or approximately the same. Therefore, the input voltage of the first inverter 15 and the input voltage of the second inverter 22 can be the same or approximately the same. Furthermore, since the first rectifier circuit and the second rectifier circuit are connected in series, the currents flowing through the first inverter 15 and the second inverter 22 are equal to each other.

[0045] Therefore, the power supplied from the first voltage source 11 and the second voltage source 18 to the first voltage conversion circuit and the second voltage conversion circuit is always equal, and is not affected by fluctuations in the first voltage source 11 and the second voltage source 18. Therefore, there is no need to set the withstand voltage performance or allowable current amount of the first voltage conversion circuit and the second voltage conversion circuit unnecessarily high, and the installation area and installation costs can be reduced.

[0046] Furthermore, the first voltage conversion circuit and the second voltage conversion circuit can always operate under similar operating conditions (voltage, current, and power), making it easier to achieve stable operation.

[0047] FIG. 2 is an explanatory diagram of a specific circuit example of the first embodiment. In FIG. 2, parts corresponding to those in FIG. 1 are given the same reference numerals. The first input chopper 12 includes a coil L2 having one end connected to the high potential side of the first voltage source 11, an N-channel MOS transistor Q7 having a drain terminal connected to the other end of the coil L2, an N-channel MOS transistor Q8 having a drain terminal connected to the other end of the coil L2 and a source terminal connected to the low potential side of the first voltage source 11, and a smoothing capacitor C2 having one end connected to the source terminal of the N-channel MOS transistor Q7 and the other end connected to the low potential side of the first voltage source 11. In this case, the first input chopper 12 functions as a synchronous rectification chopper.

[0048] The first output chopper 14 includes an N-channel MOS transistor Q1 having a drain terminal connected to a source terminal of the N-channel MOS transistor, an N-channel MOS transistor Q2 having a drain terminal connected to the source terminal of the N-channel MOS transistor Q1 and a source terminal connected to the low potential side of the first voltage source 11, a coil L1 having one end connected to the source terminal of the N-channel MOS transistor Q1, and a capacitor C1 having one end connected to the other end of the coil L1 and the other end connected to the low potential side of the first voltage source 11, and functioning as a low pass filter in cooperation with the coil L1.

[0049] The first inverter 15 includes an N-channel MOS transistor Q3 having a drain terminal connected to the other end of the coil L1 of the first output chopper 14, an N-channel MOS transistor Q4 having a drain terminal connected to the source terminal of the N-channel MOS transistor Q3 and a source terminal connected to the low potential side of the first voltage source 11, an N-channel MOS transistor Q5 having a drain terminal connected to the other end of the coil L1 of the first output chopper 14, an N-channel MOS transistor Q6 having a drain terminal connected to the source terminal of the N-channel MOS transistor Q5 and a source terminal connected to the low potential side of the first voltage source 11, a coil L3 having one end connected to the source terminal of the N-channel MOS transistor Q3, and a capacitor C3 having one end connected to the other end of the coil L3.

[0050] In this case, the coil L3 and the capacitor C3 function as a resonant circuit and have an impedance of a predetermined resonant frequency. For example, the first inverter 15 has a resonant frequency that resonates with the switching frequency of the N-channel MOS transistors Q3 to Q6 that function as switches.

[0051] The first transformer 16 has one terminal on the primary side connected to the other end of the capacitor C3, and the other terminal on the primary side connected to the source terminal of an N-channel MOS transistor Q5 and the drain terminal of an N-channel MOS transistor Q6.

[0052] The first rectifier circuit 17 includes a diode D1 having an anode terminal connected to one terminal of the secondary side of the first transformer 16, a smoothing capacitor C4 having one terminal connected to the cathode terminal of the diode D1 and the other terminal connected to the other terminal of the secondary side of the first transformer 16, a diode D2 having a cathode terminal connected to one terminal of the secondary side of the first transformer 16, and a smoothing capacitor C5 having one terminal connected to the other terminal of the secondary side of the first transformer 16 and the other terminal connected to the anode terminal of the diode D2.

[0053] The second input chopper 19 includes a coil L12 having one end connected to the high potential side of the second voltage source 18, an N-channel MOS transistor Q17 having a drain terminal connected to the other end of the coil L12, an N-channel MOS transistor Q18 having a drain terminal connected to the other end of the coil L12 and a source terminal connected to the low potential side of the second voltage source 18, and a smoothing capacitor C12 having one end connected to the source terminal of the N-channel MOS transistor Q17 and the other end connected to the low potential side of the second voltage source 18. In this case, the second input chopper 19 functions as a synchronous rectification chopper.

[0054] The second output chopper 21 includes an N-channel MOS transistor Q11 having a drain terminal connected to a source terminal of the N-channel MOS transistor, an N-channel MOS transistor Q12 having a drain terminal connected to the source terminal of the N-channel MOS transistor Q11 and a source terminal connected to the low potential side of the second voltage source 18, a coil L11 having one end connected to the source terminal of the N-channel MOS transistor Q11, and a capacitor C11 having one end connected to the other end of the coil L11 and the other end connected to the low potential side of the second voltage source 18, and functioning as a low pass filter in cooperation with the coil L11.

[0055] The second inverter 22 includes an N-channel MOS transistor Q13 having a drain terminal connected to the other end of the coil L11 of the second output chopper 21, an N-channel MOS transistor Q14 having a drain terminal connected to the source terminal of the N-channel MOS transistor Q13 and a source terminal connected to the low potential side of the second voltage source 18, an N-channel MOS transistor Q15 having a drain terminal connected to the other end of the coil L11 of the second output chopper 21, an N-channel MOS transistor Q16 having a drain terminal connected to the source terminal of the N-channel MOS transistor Q15 and a source terminal connected to the low potential side of the second voltage source 18, a coil L13 having one end connected to the source terminal of the N-channel MOS transistor Q13, and a capacitor C13 having one end connected to the other end of the coil L13.

[0056] The second transformer 23 has one terminal on the primary side connected to the other end of the capacitor C13, and the other terminal on the primary side connected to the source terminal of an N-channel MOS transistor Q15 and the drain terminal of an N-channel MOS transistor Q16.

[0057] The second rectifier circuit 24 includes a diode D11 having an anode terminal connected to the high potential side terminal of the secondary side of the second transformer 23, a smoothing capacitor C4 having one terminal connected to the cathode terminal of the diode D11 and the other terminal connected to the low potential side terminal of the secondary side of the first transformer 16, a diode D12 having a cathode terminal connected to the high potential side terminal of the secondary side of the first transformer 16, and a smoothing capacitor C15 having one terminal connected to the low potential side terminal of the secondary side of the second transformer 23 and the other terminal connected to the anode terminal of the diode D12.

[0058] Furthermore, between the load LD and the first rectifier circuit 17 and the second rectifier circuit 24, a low-pass filter 25 including a coil L4 and a capacitor C6 is provided.

[0059] Here, the effects of the embodiment will be described with reference to a comparison circuit having a conventional configuration. FIG. 3 is an explanatory diagram of a comparative example. The DC power supply device 10P of the comparative example includes a first voltage source 51, a first low-pass filter 52, a first input chopper 53, a first inverter 54, a first transformer 55, a first rectifier circuit 56, a second voltage source 57, a second low-pass filter 58, a second input chopper 59, a second inverter 60, a second transformer 61, a second rectifier circuit 62, a third low-pass filter 63, and a control circuit 64.

[0060] In the above configuration, the first low-pass filter 52, the first input chopper 53, the first inverter 54, the first transformer 55 and the first rectifier circuit 56 configure a first voltage conversion circuit. Further, the second low-pass filter 58, the second input chopper 59, the second inverter 60, the second transformer 61 and the second rectifier circuit 62 configure a second voltage conversion circuit. The first voltage conversion circuit and the second voltage conversion circuit are connected in parallel.

[0061] The first voltage source 51 functions as a DC voltage source and outputs DC power having a first voltage to the first low-pass filter 52 .

[0062] The first low-pass filter 52 has a coil L22 having one end connected to the high potential side of the first voltage source 51, and a capacitor C22 having one end connected to the other end of the coil L22 and the other end connected to the low potential side of the first voltage source 51, and removes harmonic components from the DC power output by the first voltage source 51 and outputs it to the first input chopper 53.

[0063] The first input chopper 53 has an N-channel MOS transistor Q21 having a drain terminal connected to the other end of the coil L22, an N-channel MOS transistor Q22 having a drain terminal connected to the source terminal of the N-channel MOS transistor Q21 and a source terminal connected to the low potential side of a second voltage source 57, a coil L21 having one terminal connected to the source terminal of the N-channel MOS transistor Q21, and a capacitor C21 having one terminal connected to the other terminal of the coil L21 and the other terminal connected to the low potential side of the first voltage source 51, and steps down the voltage of the first voltage source 51, removes harmonic components from the stepped-down DC power, and outputs it to the first inverter 54.

[0064] The first inverter 54 includes an N-channel MOS transistor Q23 having a drain terminal connected to the other end of the coil L21 of the first input chopper 53, an N-channel MOS transistor Q24 having a drain terminal connected to the source terminal of the N-channel MOS transistor Q23 and a source terminal connected to the low potential side of the first voltage source 51, an N-channel MOS transistor Q25 having a drain terminal connected to the other end of the coil L21 of the first input chopper 53, an N-channel MOS transistor Q26 having a drain terminal connected to the source terminal of the N-channel MOS transistor Q25 and a source terminal connected to the low potential side of the first voltage source 11, a coil L23 having one end connected to the source terminal of the N-channel MOS transistor Q23, and a capacitor C23 having one end connected to the other end of the coil L23. The first inverter 54 converts the DC power stepped down by the first input chopper 53 into AC power, and outputs the AC power to the first transformer 55 by passing only components in a predetermined frequency range.

[0065] The first transformer 55 has one primary terminal connected to the other end of the capacitor C23 and the other primary terminal connected to the source terminal of an N-channel MOS transistor Q25 and the drain terminal of an N-channel MOS transistor Q26, and transforms the input AC power at a predetermined transformation ratio and outputs it to the first rectifier circuit 56.

[0066] The first rectifier circuit 56 has a diode D21 having an anode terminal connected to the high potential side terminal of the secondary side of the first transformer 55, a smoothing capacitor C24 having one terminal connected to the cathode terminal of the diode D21 and the other terminal connected to the low potential side terminal of the first transformer 55, a diode D22 having a cathode terminal connected to the high potential side terminal of the secondary side of the first transformer 55, and a smoothing capacitor C25 having one terminal connected to the low potential side terminal of the secondary side of the first transformer secondary side 55 and the other terminal connected to the anode terminal of the diode D22, and rectifies the input AC power and outputs it as DC power to the low pass filter 63.

[0067] The second voltage source 57 functions as a DC voltage source and outputs DC power having a second voltage to the second low-pass filter 58 .

[0068] The second low-pass filter 58 has a coil L32 having one end connected to the high potential side of the second voltage source 57, and a capacitor C32 having one end connected to the other end of the coil L32 and the other end connected to the low potential side of the second voltage source 57, and removes harmonic components from the DC power output by the second voltage source 57 and outputs it to the second input chopper 59.

[0069] The second input chopper 59 has an N-channel MOS transistor Q31 having a drain terminal connected to the other end of the coil L32, an N-channel MOS transistor Q32 having a drain terminal connected to the source terminal of the N-channel MOS transistor Q31 and a source terminal connected to the low potential side of the second voltage source 57, a coil L31 having one terminal connected to the source terminal of the N-channel MOS transistor Q31, and a capacitor C31 having one terminal connected to the other terminal of the coil L31 and the other terminal connected to the low potential side of the second voltage source 57, and steps down the voltage of the second voltage source 57, removes harmonic components from the stepped-down DC power, and outputs it to the second inverter 60.

[0070] The second inverter 60 includes an N-channel MOS transistor Q33 having a drain terminal connected to the other end of the coil L31 of the second input chopper 59, an N-channel MOS transistor Q34 having a drain terminal connected to the source terminal of the N-channel MOS transistor Q33 and a source terminal connected to the low potential side of the second voltage source 57, an N-channel MOS transistor Q35 having a drain terminal connected to the other end of the coil L31 of the second input chopper 59, an N-channel MOS transistor Q36 having a drain terminal connected to the source terminal of the N-channel MOS transistor Q35 and a source terminal connected to the low potential side of the second voltage source 57, a coil L33 having one end connected to the source terminal of the N-channel MOS transistor Q33, and a capacitor C33 having one end connected to the other end of the coil L33. The second inverter 60 converts the DC power stepped down by the second input chopper 59 into AC power, and outputs the AC power to the second transformer 61 by passing only components in a predetermined frequency range.

[0071] The second transformer 61 has one primary terminal connected to the other end of the capacitor C33 and the other primary terminal connected to the source terminal of an N-channel MOS transistor Q35 and the drain terminal of an N-channel MOS transistor Q36, and transforms the input AC power at a predetermined transformation ratio and outputs it to the second rectifier circuit 62.

[0072] The second rectifier circuit 62 has a diode D31 having an anode terminal connected to the high potential side terminal of the secondary side of the second transformer 61, a smoothing capacitor C34 having one terminal connected to the cathode terminal of the diode D31 and the other terminal connected to the low potential side terminal of the secondary side of the second transformer 61, a diode D32 having a cathode terminal connected to the high potential side terminal of the secondary side of the second transformer 61, and a smoothing capacitor C35 having one terminal connected to the low potential side terminal of the secondary side of the second transformer 61 and the other terminal connected to the anode terminal of the diode D32, and rectifies the input AC power and outputs it as DC power to the third low-pass filter 63.

[0073] The third low-pass filter 63 has a coil L24 having one end connected to the cathode terminal of the diode D21 that constitutes the first rectifier circuit and the cathode terminal of the diode D31 that constitutes the second rectifier circuit, and the other end connected to one end of the load circuit LD, and a capacitor C26 having one end connected to the other end of the coil L24 and the other end connected to the anode terminal of the diode D22 that constitutes the first rectifier circuit 56 and the anode terminal of the diode D32 that constitutes the second rectifier circuit 62, and the other end connected to the other end of the load circuit LD, and removes harmonic components from the combined power of the output power of the first rectifier circuit 56 and the output power of the second rectifier circuit 62, and outputs the combined power to the load circuit LD.

[0074] Furthermore, since the first voltage source 51 and the second voltage source 57 do not operate in conjunction with each other, their voltages differ within the range permitted for commercial power sources, for example.

[0075] [1] Simulation results of specific operations of the comparative example Next, a simulation result of a specific operation of the comparative example will be described. In this simulation, the following values ​​are used as an example. The inductance of the coil L22 constituting the first low-pass filter is set to 100 μH, and the capacitance of the capacitor C22 is set to 200 μF.

[0076] The operating frequencies of the N-channel MOS transistors Q21 and Q22 constituting the first input chopper 53 are each set to 295 kHz, the inductance of the coil L21 is set to 60 μH, and the capacitance of the capacitor C21 is set to 8 μF. The operating frequency of each of the N-channel MOS transistors Q23 to Q26 constituting the first inverter 54 is set to 175 kHz.

[0077] The winding ratio between the primary and secondary sides of the first transformer 55 is set to 1:4. The capacitance of each of the smoothing capacitors C24 and C25 constituting the first rectifier circuit 56 is set to 1 μF.

[0078] The operating frequencies of the N-channel MOST transistors Q31 and Q32 constituting the second input chopper 59 are each set to 295 kHz, the inductance of the coil L31 is set to 60 μH, and the capacitance of the capacitor C31 is set to 8 μF. The operating frequency of each of the N-channel MOS transistors Q33 to Q36 constituting the second inverter 60 is set to 175 kHz.

[0079] The winding ratio between the primary and secondary sides of the second transformer 61 is set to 1:4. The capacitance of each of the smoothing capacitors C34 and C35 constituting the second rectifier circuit 62 is set to 1 μF.

[0080] The inductance of the coil L24 constituting the third low-pass filter 63 is set to 50 μH, and the capacitance of the capacitor C26 is set to 1.1 μF. Furthermore, the resistance value of the load circuit LD is set to 100Ω.

[0081] [1.1] Ideal operation First, the ideal operation will be described. Ideally, the voltage of the first voltage source 51 is equal to the voltage of the second voltage source 57. Here, as an example, the voltage of the first voltage source 51 and the voltage of the second voltage source 57 are set to 400V. Ideally, the circuit constants are also equal. As an example, the inductances of the coils L23 and L33, whose values ​​have not been determined, are assumed to be equal at 5.2 μH.

[0082] FIG. 4 is an explanatory diagram (part 1) of the results of an operational simulation of the comparative example. FIG. 4(A) is an explanatory diagram of the input power amount. In an ideal operating state, the voltage of the first voltage source 51 and the voltage of the second voltage source 57 are equal (=400V), so the input power PW11 to the first inverter 54 side and the input power PW12 to the second inverter 60 side are naturally equal. For this reason, in FIG. 4(A), both waveforms overlap each other, so that a single waveform is shown.

[0083] FIG. 4B is an explanatory diagram of the currents in the first inverter 54 and the second inverter 60. As shown in FIG. As described above, the voltage of the first voltage source 51 and the voltage of the second voltage source 57 are equal, and the input power PW11 to the first inverter 54 side by the first voltage source 51 and the input power PW12 to the second inverter 60 side are equal, so the phase and amplitude of the current I11 of the first inverter 54 and the current I12 of the second inverter 60 are also equal. For this reason, in FIG. 4(B), both waveforms are overlapped, and thus a single waveform is shown.

[0084] FIG. 4C is an explanatory diagram of the output voltage of the DC power supply device 10P. The output voltage Vout of the DC power supply 10P to the load circuit LD is controlled to a constant value by the control circuit 64, as shown in FIG.

[0085] FIG. 4(D) is an explanatory diagram of the output current of the DC power supply device 10P. The output current Iout of the DC power supply device 10P to the load circuit LD is rectified by the third low-pass filter 63 as shown in FIG. 4(D) and is therefore constant.

[0086] As described above, in an ideal operating state, the output voltage Vout supplied to the load circuit LD is a predetermined voltage controlled by the control circuit.

[0087] [1.2] When the voltage of the first voltage source and the voltage of the second voltage source are not the same However, first voltage source 51 and second voltage source 57 are connected to separate commercial systems and operate separately, and therefore, unlike an ideal state, the voltages, frequencies, etc. are not necessarily the same. Therefore, the operation in such a case was simulated. Other operating conditions are assumed to be the same as in the ideal operating conditions.

[0088] More specifically, the simulation was performed with the voltage Vin1 of the first voltage source 51 set to 380V and the voltage Vin2 of the second voltage source 57 set to 420V.

[0089] FIG. 5 is a diagram (part 2) illustrating the results of an operational simulation of the comparative example. FIG. 5(A) is an explanatory diagram of the input power amount. When the voltage Vin1 of the first voltage source 51 is 380V and the voltage Vin2 of the second voltage source 57 is 420V, the input power PW11 to the first inverter 54 side is naturally lower than the input power PW12 to the second inverter 60 side. In the comparative example, the waveform is as shown in FIG. 5(A), and the input power PW11 to the first inverter 54 side and the input power PW12 to the second inverter 60 side are clearly different.

[0090] FIG. 5B is an explanatory diagram of the currents in the first inverter 54 and the second inverter 60. As shown in FIG. As described above, since the voltage of the first voltage source 51 and the voltage of the second voltage source 57 are different and the input power PW12 to the second inverter 60 side is greater than the input power PW11 to the first inverter 54 side by the first voltage source 51, the amplitude of the current I11 of the first inverter 54 is smaller than the amplitude of the current I12 of the second inverter 60. In this case, the first inverter 54 and the second inverter 60 are controlled by the control circuit 64, and the phase of the current I11 of the first inverter 54 and the phase of the current I12 of the second inverter 60 are equal. This results in a waveform as shown in FIG. 5(B).

[0091] FIG. 5C is an explanatory diagram of the output voltage of the DC power supply device 10P. Even if the voltages of the first voltage source 51 and the second voltage source 57 are different, the output voltage Vout to the load circuit LD is constant.

[0092] FIG. 5(D) is an explanatory diagram of the output current of the DC power supply device 10P. The output current Iout of the DC power supply device 10P to the load circuit LD is rectified by the third low-pass filter 63 as shown in FIG. 5(D) and is therefore constant.

[0093] As described above, even in an operating state in which the voltage of first voltage source 51 and the voltage of second power source 57 are not the same, output voltage Vout supplied to load circuit LD becomes a predetermined voltage controlled by the control circuit.

[0094] However, the power supplied to the load circuit LD by the first voltage conversion circuit composed of the first voltage source 51, the first low-pass filter 52, the first input chopper 53, the first inverter 54, the first transformer 55, and the first rectifier circuit 56 is significantly different from the power supplied to the load circuit LD by the second voltage conversion circuit composed of the second voltage source 57, the second low-pass filter 58, the second input chopper 59, the second inverter 60, the second transformer 61, and the second rectifier circuit 62, resulting in a power imbalance between the first and second voltage conversion circuits and resulting in the power handled by each voltage conversion circuit being significantly different.

[0095] In other words, the amount of power supplied by the first voltage source 51 and the amount of power supplied by the second voltage source 57 will differ significantly, resulting in an imbalance between the power supplied to the first inverter 54 and the power supplied to the second inverter 60. In order to deal with this imbalance, it is necessary to use components that have a high withstand voltage, current capacity, etc., for the components that make up each inverter, which increases the size and cost of the device.

[0096] [1.3] When the circuit constants are not identical Next, the results of a simulation in the case where the circuit constants are not the same will be described. For ease of understanding, in the first voltage conversion circuit and the second voltage conversion circuit, the inductance of coil L23, whose value was not specified, is set to 4.2 μH, and the inductance of coil L33, whose value was also not specified, is set to 6.2 μH, and all other circuit constants are assumed to be equal.

[0097] FIG. 6 is an explanatory diagram (part 3) of the operation simulation result of the comparative example. FIG. 6(A) is an explanatory diagram of the input power amount. Even when the voltage Vin1 of the first voltage source 51 is 400V and the voltage Vin2 of the second voltage source 57 is 400V, if the inductance of the coil L23 is 4.2μH and the inductance of the coil L33 is 6.2μH, as shown in FIG. 6(A), the input power PW11 to the first inverter 54 side is higher than the input power PW12 to the second inverter 60 side.

[0098] FIG. 6B is an explanatory diagram of the currents in the first inverter 54 and the second inverter 60. As shown in FIG. As described above, since the input power PW11 to the first inverter 54 side is higher than the input power PW12 to the second inverter 60 side, the amplitude of the current I11 of the first inverter 54 is larger than the amplitude of the current I12 of the second inverter 60. Even in this case, the first inverter 54 and the second inverter 60 are controlled by the control circuit 64, and the phase of the current I11 of the first inverter 54 and the phase of the current I12 of the second inverter 60 are equal. This results in a waveform as shown in FIG. 6(B).

[0099] FIG. 6C is an explanatory diagram of the output voltage of the DC power supply device 10P. Even if the circuit constants (in the above example, the inductances of the coils L23 and L33) are different, the output voltage Vout to the load circuit LD is constant because it is controlled by the control circuit 64.

[0100] FIG. 6D is an explanatory diagram of the output current of the DC power supply device 10P. The output current Iout of the DC power supply device 10P to the load circuit LD is rectified by the third low-pass filter 63 as shown in FIG. 6(D) and is therefore constant.

[0101] As described above, even if some of the circuit constants are in a different operating state, the output voltage Vout and output current Iout supplied to the load circuit LD are predetermined voltage and current.

[0102] However, the power supplied to the load circuit LD by the first voltage conversion circuit composed of the first voltage source 51, the first low-pass filter 52, the first input chopper 53, the first inverter 54, the first transformer 55, and the first rectifier circuit 56 is significantly different from the power supplied to the load circuit LD by the second voltage conversion circuit composed of the second voltage source 57, the second low-pass filter 58, the second input chopper 59, the second inverter 60, the second transformer 61, and the second rectifier circuit 62, resulting in a power imbalance between the first and second voltage conversion circuits and resulting in the power handled by each voltage conversion circuit being significantly different.

[0103] In other words, the amount of power supplied by the first voltage source 51 and the amount of power supplied by the second voltage source 57 will differ significantly, resulting in an imbalance between the power supplied to the first inverter 54 and the power supplied to the second inverter 60.

[0104] In order to deal with this imbalance, it is necessary to use components that have a large withstand voltage, current capacity, etc. for the components that make up each inverter, just as in the case where the voltages of the first voltage source 51 and the second voltage source are different, which results in an increase in the size and cost of the device.

[0105] [2] Simulation results of specific operation of the embodiment Next, a simulation result of a specific operation of the embodiment will be described. In this simulation, the following values ​​are used as an example.

[0106] The operating frequencies of the N-channel MOS transistors Q7 and Q8 constituting the first input chopper 12 are set to 225 kHz, the inductance of the coil L2 is set to 100 μH, and the capacitance of the capacitor C2 is set to 200 μF. In addition, the control voltage (target output voltage) of the first input chopper 12 is set to Vdc=500 V.

[0107] The operating frequency of the N-channel MOS transistors Q1 and Q2 constituting the first output chopper 14 is set to 295 kHz, the inductance of the coil L1 is set to 60 μH, and the capacitance of the capacitor C1 is set to 8 μF.

[0108] The operating frequency of each of the N-channel MOS transistors Q3 to Q6 constituting the first inverter 15 is set to 175 kHz. The winding ratio between the primary and secondary sides of the first transformer 16 is set to 1:2. The capacitance of each of the smoothing capacitors C4 and C5 constituting the first rectifier circuit 17 is set to 1 μF.

[0109] The operating frequencies of the N-channel MOS transistors Q17 and Q18 constituting the second input chopper 19 are set to 225 kHz, the inductance of the coil L12 is set to 100 μH, and the capacitance of the capacitor C12 is set to 200 μF. In addition, the control voltage (target output voltage) of the second input chopper 19 is set to Vdc=500 V.

[0110] The operating frequencies of the N-channel MOS transistors Q11 and Q12 constituting the second output chopper 21 are each set to 295 kHz, the inductance of the coil L11 is set to 60 μH, and the capacitance of the capacitor C11 is set to 8 μF. The operating frequency of each of the N-channel MOS transistors Q13 to Q16 constituting the second inverter 22 is set to 175 kHz.

[0111] The winding ratio between the primary side and the secondary side of the second transformer 23 is set to 1:2. The capacitance of each of the smoothing capacitors C14 and C15 constituting the second rectifier circuit 24 is set to 1 μF.

[0112] The inductance of the coil L24 constituting the third low-pass filter 63 is set to 50 μH, and the capacitance of the capacitor C26 is set to 1.1 μF. Furthermore, the resistance value of the load circuit LD is set to 100Ω.

[0113] Next, referring again to FIG. 2, the results of the simulation of the embodiment will be described. [2.1] Ideal operation First, the ideal operation will be described. Ideally, the voltage of the first voltage source 11 is equal to the voltage of the second voltage source 18. Here, as an example, the voltage of the first voltage source 11 and the voltage of the second voltage source 18 are set to 400V.

[0114] Ideally, the circuit constants are also equal. As an example, the inductances of the coils L3 and L13, whose values ​​have not been specified, are set to 5.2 μH, and the circuit constants of the other circuit components that correspond to each other are all set to the same value, as described above.

[0115] FIG. 7 is a diagram (part 1) illustrating the results of an operational simulation of the embodiment. FIG. 7(A) is an explanatory diagram of the input power amount. In an ideal operating state, the voltage of the first voltage source 11 and the voltage of the second voltage source 18 are equal (=400 V), so naturally the input power PW1 supplied to the first inverter 15 side via the first input chopper 12 and the input power PW2 supplied to the second inverter 22 side via the second input chopper 19 are equal.

[0116] 7(A), the two waveforms overlap and are shown as one waveform. Note that the voltage is not constant because the voltage is boosted by the first input chopper 12 or the second input chopper 19.

[0117] FIG. 7B is an explanatory diagram of the currents of the first inverter 15 and the second inverter 22. As shown in FIG. As described above, the voltage of the first voltage source 11 and the voltage of the second voltage source 18 are equal, and the input power PW1 to the first inverter 15 side supplied by the first voltage source 11 via the first input chopper 12 is equal to the input power PW12 to the second inverter 22 side supplied by the second voltage source 18 via the second input chopper 19, so the phase and amplitude of the current I1 of the first inverter 15 and the current I2 of the second inverter 22 are also equal. Note that the phase of the waveform is controlled by the control circuit 27 so that the phases of the first inverter 15 and the second inverter 22 are the same. For this reason, in FIG. 7(B), both waveforms are overlapped to form one waveform.

[0118] FIG. 7C is an explanatory diagram of the output voltage of the DC power supply device 10. The output voltage Vout of the DC power supply 10 to the load circuit LD is controlled to a constant value by the control circuit 27, as shown in FIG.

[0119] FIG. 7D is an explanatory diagram of the output current of the DC power supply device 10. The output current Iout of the negative DC power supply 10 to the load circuit LD is rectified by the low-pass filter 25 as shown in FIG. 7(D) and is therefore constant. As described above, in an ideal operating state, the output voltage Vout and the output current Iout supplied to the load circuit LD are predetermined voltages and currents controlled by the control circuit.

[0120] [2.2] When the voltage of the first voltage source and the voltage of the second voltage source are not the same Incidentally, first voltage source 11 and second voltage source 18 are connected to separate commercial power systems and operate separately, and therefore, unlike an ideal state, the voltages, frequencies, etc. are generally not necessarily the same. Therefore, the operation of the embodiment was also simulated for such a case.

[0121] Other operating conditions are assumed to be the same as in the ideal operating conditions. More specifically, the simulation was performed with the voltage Vin1 of the first voltage source 11 set to 380V and the voltage Vin2 of the second voltage source 18 set to 420V.

[0122] FIG. 8 is a diagram (part 2) illustrating the results of an operational simulation of the embodiment. FIG. 8(A) is an explanatory diagram of the input power amount. Even when the voltage Vin1 of first voltage source 11 is 380V and the voltage Vin2 of second voltage source 18 is 420V, the voltage of first voltage source 11 is adjusted by first input chopper 12 to be the specified voltage Vdc and is output, and the voltage of second voltage source 18 is adjusted by second input chopper 19 to be the specified voltage Vdc and is output, so that from the perspective of first inverter 15 or second inverter 22, DC power having the specified voltage Vdc is supplied in either case.

[0123] Therefore, even if the voltage of the first voltage source 11 and the voltage of the second voltage source 18 are different, the output voltage of the first inverter 15 and the output voltage of the second inverter 22 can be made the same or approximately the same. Furthermore, since the first rectifier circuit and the second rectifier circuit are connected in series, the currents flowing through the first inverter 15 and the second inverter 22 are equal. Therefore, the power supplied from the first voltage source 11 and the second voltage source 18 to the first voltage conversion circuit and the second voltage conversion circuit is always equal, and is not affected by fluctuations in the first voltage source 11 and the second voltage source 18.

[0124] Therefore, the input power PW1 to the first inverter 15 side and the input power PW2 to the second inverter 22 side are almost equal. The input powers are not completely equal because, unlike the ideal operating state, the actual voltage of the first voltage source 11 and the voltage of the second voltage source are different, and therefore the processing time required for feedback to reach the predetermined voltage Vdc and the like differ. However, effectively, the difference is within a range that allows it to be regarded as if the same power is being supplied to the first voltage conversion circuit and the second voltage conversion circuit.

[0125] FIG. 8B is an explanatory diagram of the currents in the first inverter 15 and the second inverter 22. As shown in FIG. As described above, even if the voltage of the first voltage source 11 and the voltage of the second voltage source 18 are different, the output voltage of the first inverter 15 and the output voltage of the second inverter 22 can be made the same or approximately the same. Furthermore, since the first rectifier circuit and the second rectifier circuit are connected in series, the currents flowing through the first inverter 15 and the second inverter 22 are equal. Therefore, the phase and amplitude of the current I1 of the first inverter 15 and the current I2 of the second inverter 22 are also equal. For this reason, in FIG. 8(B), both waveforms are overlapped to form a single waveform.

[0126] FIG. 8C is an explanatory diagram of the output voltage of the DC power supply device 10. The output voltage Vout of the DC power supply 10 to the load circuit LD is controlled to a constant value by the control circuit 27, as shown in FIG. 8(C). FIG. 8(D) is an explanatory diagram of the output current of the DC power supply device 10. The output current Iout of the DC power supply device 10 to the load circuit LD is rectified by the low-pass filter 25 as shown in FIG. 8(D) and is therefore constant. As described above, in an ideal operating state, the output voltage Vout and the output current Iout supplied to the load circuit LD are predetermined voltages and currents controlled by the control circuit.

[0127] [2.3] When the circuit constants are not identical Next, the results of a simulation in the case where the circuit constants are not the same will be described. For ease of understanding, in the first voltage conversion circuit and the second voltage conversion circuit, the inductance of coil L3, whose value was not specified, is set to 4.2 μH, and the inductance of coil L13, whose value was also not specified, is set to 6.2 μH, and all other circuit constants are assumed to be equal.

[0128] FIG. 9 is a diagram (part 3) for explaining the results of an operational simulation of the embodiment. FIG. 9(A) is an explanatory diagram of the input power amount. Even when the voltage Vin1 of the first voltage source 11 is 400V and the voltage Vin2 of the second voltage source 18 is 400V, if the inductance of the coil L3 is 4.2μH and the inductance of the coil L13 is 6.2μH, as shown in FIG. 9(A), the input power PW1 to the first inverter 15 side is slightly lower than the input power PW2 to the second inverter 22 side.

[0129] FIG. 9B is an explanatory diagram of the currents in the first inverter 15 and the second inverter 22. As shown in FIG. As described above, since the input power PW1 to the first inverter 15 side is slightly lower than the input power PW12 to the second inverter 22 side, the amplitude of the current I1 of the first inverter 15 is slightly smaller than the amplitude of the current I2 of the second inverter 22. Even in this case, the first inverter 15 and the second inverter 22 are controlled by the control circuit 27, and the phase of the current I1 of the first inverter 15 and the phase of the current I2 of the second inverter 22 are equal. This results in a waveform as shown in FIG. 9(B).

[0130] FIG. 9C is an explanatory diagram of the output voltage of the DC power supply device 10. Even if the circuit constants (in the above example, the inductance of coil L3 and the inductance of coil L13) are different, the output voltage Vout to the load circuit LD is controlled by the control circuit 27, and therefore is almost constant, although it fluctuates slightly due to differences in the circuit constants.

[0131] FIG. 9(D) is an explanatory diagram of the output current of the DC power supply device 10. The output current Iout to the load circuit LD is approximately constant, although it fluctuates slightly due to differences in the circuit constants. As described above, even if some of the circuit constants are in a different operating state, the output voltage Vout and output current Iout supplied to the load circuit LD are predetermined voltage and current.

[0132] As described above, the power from the first voltage source 11 and the second voltage source 18 that is effectively processed by the voltage conversion circuit is controlled by the first input chopper 12 and the second input chopper 19 to a value closer to the ideal power.

[0133] Furthermore, since the first rectifier circuit 17 and the second rectifier circuit 24 are connected in series, the currents flowing through the first voltage conversion circuit and the second voltage conversion circuit are approximately equal even if the voltage of the first voltage source 11 and the voltage of the second voltage source 18 fluctuate or the circuit constants are different.

[0134] Therefore, the power supplied from the first voltage source 11 and the second voltage source 18 to the first voltage conversion circuit and the second voltage conversion circuit becomes almost equal, and the effects of the voltage fluctuations of the first voltage source 11 and the voltage fluctuations of the second voltage source 18 can be effectively suppressed to a negligible level.

[0135] Therefore, there is no need to set the withstand voltage performance or allowable current amount of the first voltage conversion circuit and the second voltage conversion circuit unnecessarily high, and the installation area and installation costs can be reduced. Furthermore, the first voltage conversion circuit and the second voltage conversion circuit can always operate under similar operating conditions (voltage, current, and power), making it easier to achieve stable operation.

[0136] Next, a modification of the embodiment will be described. The difference between the embodiment and the modified example of the embodiment is that step-up choppers are used as the first input chopper and the second input chopper, and step-down choppers are used as the first output chopper and the second output chopper.

[0137] FIG. 10 is an explanatory diagram of a specific circuit example of a modified example of the first embodiment. In FIG. 10, the same parts as those in FIG. 2 are denoted by the same reference numerals, and the detailed description thereof is to be cited.

[0138] A DC power supply device 10 of a modified embodiment includes a first voltage source 11, a first input chopper 12A, a first voltage detector 13, a first output chopper 14A, a first inverter 15, a first transformer 16, a first rectifier circuit 17, a second voltage source 18, a second input chopper 19A, a second voltage detector 20, a second output chopper 21A, a second inverter 22, a second transformer 23, a second rectifier circuit 24, a voltage / current detector 26, and a control circuit 27. In this case, the configuration and operation other than the first input chopper 12A, the first output chopper 14A, the second input chopper 19A and the second output chopper 21A are the same as those in the embodiment of FIG. 2, so only the different parts will be described below.

[0139] The first input chopper 12A includes a coil L2 having one end connected to the high potential side of the first voltage source 11, an N-channel MOS transistor Q7 having a drain terminal connected to the other end of the coil L2, a diode D4 having an anode terminal connected to the high potential side of the first voltage source 11, and a smoothing capacitor C2 having one end connected to the cathode terminal of the diode D4 and the other end connected to the low potential side of the first voltage source 11. In this case, the first input chopper 12A is configured as a boost chopper and functions as a first voltage adjustment circuit, and outputs the voltage of the input DC power to the first output chopper 14A as a first predetermined voltage value based on the detection result of the first voltage detector 13.

[0140] The first output chopper 14A includes an N-channel MOS transistor Q1 having a drain terminal connected to the cathode terminal of a diode D4, a diode D3 having a cathode terminal connected to the source terminal of the N-channel MOS transistor Q1 and an anode terminal connected to the low potential side of the first voltage source 11, a coil L1 having one end connected to the source terminal of the N-channel MOS transistor Q1, and a capacitor C1 having one end connected to the other end of the coil L1 and the other end connected to the low potential side of the first voltage source 11, and functioning as a low pass filter in cooperation with the coil L1. In this case, the first output chopper 14A functions as a second voltage adjustment circuit, and outputs the voltage of the input DC power to the first inverter 15 as a second predetermined voltage value based on the voltage detection result of the voltage / current detector 26.

[0141] The second input chopper 19A includes a coil L12 having one end connected to the high potential side of the second voltage source 18, an N-channel MOS transistor Q17 having a drain terminal connected to the other end of the coil L12, a diode D14 having an anode terminal connected to the high potential side of the second voltage source 18, and a smoothing capacitor C12 having one end connected to the cathode terminal of the diode D14 and the other end connected to the low potential side of the second voltage source 18. In this case, the second input chopper 19A is configured as a boost chopper and functions as a first voltage adjustment circuit, and outputs the voltage of the input DC power to the second output chopper 21A as a first predetermined voltage value based on the detection result of the second voltage detector 20.

[0142] The second output chopper 21A includes an N-channel MOS transistor Q11 having a drain terminal connected to the cathode terminal of a diode D14, a diode D13 having a cathode terminal connected to the source terminal of the N-channel MOS transistor Q11 and an anode terminal connected to the low potential side of a second voltage source 18, a coil L11 having one end connected to the source terminal of the N-channel MOS transistor Q11, and a capacitor C11 having one end connected to the other end of the coil L11 and the other end connected to the low potential side of the second voltage source 18, and functioning as a low pass filter in cooperation with the coil L11. In this case, the second output chopper 21A functions as a second voltage adjustment circuit, and outputs the voltage of the input DC power to the second inverter 22 as a second predetermined voltage value based on the voltage detection result of the voltage / current detector 26.

[0143] As described above, the power from first voltage source 11 and second voltage source 18 that is effectively processed by the voltage conversion circuit is controlled by first input chopper 12A and second input chopper 19A to a value closer to the ideal power.

[0144] Furthermore, since the first rectifier circuit 17 and the second rectifier circuit 24 are connected in series, the currents flowing through the first voltage conversion circuit and the second voltage conversion circuit are approximately equal even if the voltage of the first voltage source 11 and the voltage of the second voltage source 18 fluctuate or the circuit constants are different.

[0145] Therefore, the power supplied from the first voltage source 11 and the second voltage source 18 to the first voltage conversion circuit and the second voltage conversion circuit becomes almost equal, and the effects of the voltage fluctuations of the first voltage source 11 and the voltage fluctuations of the second voltage source 18 can be effectively suppressed to a negligible level.

[0146] For this reason, also in the modified example of this embodiment, the first voltage conversion circuit and the second voltage conversion circuit do not need to be set to unnecessarily high voltage resistance performance or allowable current amount, and the installation area and installation costs can be reduced. Furthermore, the first voltage conversion circuit and the second voltage conversion circuit can always operate under similar operating conditions (voltage, current, and power), making it easier to achieve stable operation.

[0147] In the above description, N-channel MOS transistors are used as the transistors, but the present invention is not limited to this and can be applied to P-channel MOS transistors and bipolar transistors as long as they can perform the same operation.

[0148] Furthermore, the above explanation has been given for the case where there are two voltage conversion circuits, but the same can be applied to three or more voltage conversion circuits by similarly connecting the three or more voltage conversion circuits in series.

[0149] In the above explanation, for ease of understanding, the transformer and rectifier circuit provided in each voltage conversion circuit have been described as being provided one by one in each voltage conversion circuit, but it is also possible to configure each voltage conversion circuit to have one or more of each.

[0150] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. Various modifications can be made to the embodiments. [Explanation of symbols]

[0151] 10 DC power supply 11 First voltage source 12, 12A 1st Input Chopper 13 First voltage detector 14, 14A 1st Output Chopper 15 First inverter 16 1st transformer 17 1st rectifier circuit 18 Second Voltage Source 19, 19A Second Input Chopper 20 Second voltage detector 21, 21A Second Output Chopper 22 Second inverter 23 2nd Transformer 24 Second rectifier circuit 25 Low-pass filter 26 Voltage / Current Detector 27 Control circuit Iout Output current LD load circuit LD load Vout Output voltage Vdc specified voltage Vin Voltage Vout Output voltage

Claims

1. A DC power supply circuit that converts an input DC voltage into a predetermined voltage value and outputs the voltage value to a load, n voltage conversion circuits (n: an integer of 2 or more) each including a first voltage adjustment circuit that adjusts a voltage value of a DC voltage output from a corresponding external voltage source to a first predetermined voltage value and outputs the adjusted voltage value, a second voltage adjustment circuit that adjusts a voltage value of the DC voltage output from the first voltage adjustment circuit to a second predetermined voltage value and outputs the adjusted voltage value, an inverter circuit that converts the DC voltage output from the second voltage adjustment circuit to an AC voltage, a transformer for insulating and transmitting the AC voltage output from the inverter circuit, and a rectifier circuit that rectifies the output voltage of the transformer and converts it into a DC voltage; an external output voltage detection circuit that detects a voltage between the n voltage conversion circuits and the load as an external output voltage; the DC power supply circuit is configured to generate the external output voltage by combining DC voltages output from the n voltage conversion circuits by connecting output terminals of the rectifier circuits of the n voltage conversion circuits in series; a second voltage adjustment circuit of each of the n voltage conversion circuits, which receives the voltage value of the external output voltage detected by the external output voltage detection circuit, adjusts the voltage value of the DC voltage output from the first voltage adjustment circuit based on the voltage value of the external output voltage so that the voltage value becomes the second predetermined voltage value, and outputs the adjusted voltage. DC power circuit.

2. the first voltage adjustment circuit, the second voltage adjustment circuit, the inverter circuit, the transformer, and the rectifier circuit included in each of the n voltage conversion circuits have the same configuration; 2. The DC power supply circuit according to claim 1.

3. The external voltage sources corresponding to the first voltage adjustment circuits are different voltage sources.

3. The DC power supply circuit according to claim 1 or 2.

4. The first voltage adjustment circuit is a first voltage detection circuit that detects a voltage value of an output voltage of the first voltage adjustment circuit; a first chopper that adjusts a voltage value of the DC voltage output from the corresponding external voltage source based on a detection result of the first voltage detection circuit so that the voltage value becomes the first predetermined voltage value; 2. The DC power supply circuit according to claim 1, comprising:

5. Each of the voltage conversion circuits includes a plurality of pairs of the transformer and the rectifier circuit, The transformers of the plurality of sets are connected in parallel so that the primary windings are input with the same voltage, and the secondary windings are connected to the corresponding rectifier circuits, each of the plurality of sets of rectifier circuits is configured to combine DC voltages output from each of the plurality of sets of rectifier circuits by connecting output terminals in series; 2. The DC power supply circuit according to claim 1.

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