Voltage converter

Abstract

This technology provides a way to adjust the output voltage of a switched-capacitor converter without connecting an inductor between the switches. [Solution] The voltage converter 10 comprises a first step-down circuit 20, a second step-down circuit 50, and a control unit 70. The first step-down circuit 20 includes a switch unit 21 configured with a first switch 21A and a second switch 21B connected in series, a switch unit 22 configured with a first switch 22A and a second switch 22B connected in series, a first capacitor 31, and a second capacitor 32. The first step-down circuit 20 steps down the voltage applied to the first conductive path 81 and outputs it to the intermediate conductive path 85. The second step-down circuit 50 includes a step-down chopper circuit 51 that steps down the voltage applied to the intermediate conductive path 85 and outputs it to the second conductive path 82.

Description

Technical Field

[0001] The present disclosure relates to a voltage conversion device.

Background Art

[0002] As one type of DCDC converter, a switched capacitor converter is known. A switched capacitor converter is a DCDC converter capable of stepping up or stepping down voltage by switching the connection of capacitors with switches. In addition, a switched capacitor converter that allows adjustment of the output voltage using an inductor is also known.

[0003] For example, Patent Document 1 discloses a 3-level converter provided with a flying capacitor. This 3-level converter includes two upper transistors Q1, Q2, two lower transistors Q3, Q4, capacitors CFLY and COUT, and an inductor. The upper transistors Q1, Q2 are connected in series with each other, and are connected in series with the lower transistors Q3, Q4, which are also connected in series with each other. The capacitor CFLY is connected between the transistors Q1 and Q2, and between the transistors Q3 and Q4. The inductor is connected between the transistors Q2 and Q3, and to an output node. The capacitor COUT is connected to the output node and ground.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0005] In the configuration of Patent Document 1, a configuration in which an inductor is connected between transistors is essential.

[0006] This disclosure aims to provide a technology that enables adjustment of the output voltage without connecting an inductor between the switches of a switched-capacitor converter. [Means for solving the problem]

[0007] The voltage conversion device of this disclosure, A first step-down circuit that steps down the voltage applied to the first conductive path and outputs it to the intermediate conductive path, A second step-down circuit that steps down the voltage applied to the intermediate conductive path and outputs it to the second conductive path, The system comprises a control unit that controls the first step-down circuit and the second step-down circuit, The first step-down circuit is, N switch units (where N is a natural number greater than or equal to 2) are configured by connecting a first switch and a second switch in series, N-1 first capacitors, It has N-1 second capacitors, The N switch units are arranged in series between the first conductive path and ground. In each of the aforementioned switch units, the first switch is positioned closer to the first conductive path than the second switch. Each of the aforementioned switch units has a connection portion between the first switch and the second switch, Each of the first capacitors is connected between the connection portions of adjacent switch units. Each of the aforementioned second capacitors is connected in parallel to the second and subsequent switch units from the first conductive path side. The intermediate conductive path is connected to at least one of the unit connection parts between each of the switch units. The second step-down circuit is, The system includes a step-down chopper circuit that steps down the voltage applied to the intermediate conductive path and outputs it to the second conductive path. [Effects of the Invention]

[0008] According to the technology related to the present disclosure, the output voltage can be adjusted without connecting an inductor between the switches of the switched capacitor converter. [Brief Description of Drawings]

[0009] [Figure 1] FIG. 1 is a configuration diagram of the voltage conversion device according to the first embodiment. [Figure 2] FIG. 2 is a flowchart of processing executed by the control unit according to the first embodiment. [Figure 3] FIG. 3 is a configuration diagram of the voltage conversion device according to the second embodiment. [Figure 4] FIG. 4 is a configuration diagram of a comparative example according to the second embodiment. [Figure 5] FIG. 5 is a configuration diagram of the voltage conversion device according to the third embodiment. [Figure 6] FIG. 6 is a configuration diagram of the voltage conversion device according to the fourth embodiment. [Figure 7] FIG. 7 is a configuration diagram of the voltage conversion device according to the fifth embodiment. [Mode for Carrying Out the Invention]

[0010] [Description of Embodiments of the Present Disclosure] First, the embodiments of the present disclosure will be listed and described.

[0011] [1] A first step-down circuit that steps down a voltage applied to a first conductive path and outputs the stepped-down voltage to an intermediate conductive path, a second step-down circuit that steps down a voltage applied to the intermediate conductive path and outputs the stepped-down voltage to a second conductive path, and a control unit that controls the first step-down circuit and the second step-down circuit, the first step-down circuit includes N (N is a natural number of 2 or more) switch units each having a configuration in which a first switch and a second switch are connected in series, N-1 first capacitors, and N-1 second capacitors, the N switch units are arranged in series between the first conductive path and the ground, In each of the switch units, the first switch is arranged closer to the first conductive path than the second switch, each of the switch units has a connection portion between the first switch and the second switch, each of the first capacitors is connected between the connection portions of the adjacent switch units, each of the second capacitors is connected in parallel to each of the second and subsequent switch units counted from the first conductive path side, the intermediate conductive path is connected to at least any one of the unit connection portions between the respective switch units, the second step-down circuit includes a step-down chopper circuit that steps down the voltage applied to the intermediate conductive path and outputs the stepped-down voltage to the second conductive path The voltage conversion device.

[0012] The voltage conversion device can step down the voltage applied to the first conductive path and output the stepped-down voltage to the intermediate conductive path by alternately switching the on / off states of the first switch and the second switch of the first step-down circuit constituting the switched capacitor converter. Further, the voltage conversion device can step down the voltage applied to the intermediate conductive path by the step-down chopper circuit of the second step-down circuit, output the stepped-down voltage to the second conductive path, and can also adjust the output voltage.

[0013] [2] The step-down chopper circuit has a high-side switch, the switching frequency when the control unit switches the on / off states of the first switch and the second switch is lower than the switching frequency when the control unit switches the on / off state of the high-side switch The voltage conversion device according to [1].

[0014] According to this configuration, the switching loss of the first switch and the second switch is reduced, and the step-down chopper circuit can be downsized.

[0015] [3] Comprising an inductor and a third capacitor, The inductor is connected between the ground-side end of the first capacitor and the third conductive path. The third capacitor is connected between the third conductive path and the ground. The voltage converter described in [1].

[0016] The above-described voltage converter can step down the voltage applied to the first conductive path and output it to the intermediate conductive path and the third conductive path by alternately switching the on and off states of the first and second switches. Furthermore, the control unit can adjust the voltage output to the third conductive path by adjusting the on duty cycle of the first switch.

[0017] [4] The control unit controls the first step-down circuit and the second step-down circuit so that the current output to the third conductive path is less than the current output to the second conductive path. The voltage converter described in [3].

[0018] The switch unit located closest to the first conductive path receives both the current output to the second conductive path and the current flowing through the third conductive path. Consequently, the first step-down circuit generates more heat than the second step-down circuit. In this respect, the voltage converter described above has a smaller current output to the third conductive path than to the second conductive path. Therefore, the difference in heat generation between the first and second step-down circuits can be reduced.

[0019] [5] The step-down chopper circuit has a high-side switch, The switching frequency at which the control unit switches the on / off state of the first switch and the second switch is smaller than the switching frequency at which the control unit switches the on / off state of the high-side switch. A voltage converter as described in [3] or [4].

[0020] The switch unit located closest to the first conductive path receives both the current output to the second conductive path and the current flowing through the third conductive path. Consequently, the first step-down circuit generates more heat than the second step-down circuit. In this regard, the voltage converter described above uses a configuration where the control unit controls the first and second switches at a lower switching frequency than the control unit controls the high-side switch. This reduces the switching losses of the first and second switches, thereby suppressing heat generation in the first step-down circuit. In other words, this configuration allows for a smaller difference in heat generation between the first and second step-down circuits. Furthermore, it enables miniaturization of the step-down chopper circuit.

[0021] [Details of the embodiments of this disclosure] 1. First Embodiment Figure 1 shows a voltage converter 10 according to a first embodiment. The voltage converter 10 is installed, for example, in a vehicle. The voltage converter 10 is a device that steps down the voltage applied to a first conductive path 81 and outputs it to a second conductive path 82. In this specification, the voltage is a voltage with the potential of ground 80 as the reference potential. The voltage converter 10 comprises a first step-down circuit 20, a second step-down circuit 50, and a control unit 70.

[0022] The first step-down circuit 20 steps down the voltage applied to the first conductive path 81 and outputs it to the intermediate conductive path 85. The first step-down circuit 20 includes two switch units 21 and 22, a first capacitor 31, and a second capacitor 32.

[0023] The two switch units 21 and 22 are arranged in series between the first conductive path 81 and the ground 80. The switch units 21 and 22 are arranged sequentially from the first conductive path 81 side towards the ground 80 side.

[0024] The switch unit 21 has a configuration in which a first switch 21A and a second switch 21B are connected in series between the first conductive path 81 and the ground 80. The first switch 21A is positioned closer to the first conductive path 81 than the second switch 21B. The switch unit 21 has a connection portion 21C between the first switch 21A and the second switch 21B.

[0025] The switch unit 22 has a configuration in which a first switch 22A and a second switch 22B are connected in series between the first conductive path 81 and the ground 80. The first switch 22A is positioned closer to the first conductive path 81 than the second switch 22B. The switch unit 22 has a connection portion 22C between the first switch 22A and the second switch 22B.

[0026] Each of the first switches 21A, 22A and the second switches 21B, 22B switches between an ON state that allows bidirectional current flow through it and an OFF state that restricts bidirectional current flow through it. In this embodiment, the first switches 21A, 22A and the second switches 21B, 22B are composed of N-channel MOSFETs, but they may be composed of other switches. The drains of each of the first switches 21A, 22A and the second switches 21B, 22B are connected to the conductive path on the first conductive path 81 side. The sources of each of the first switches 21A, 22A and the second switches 21B, 22B are connected to the conductive path on the ground 80 side.

[0027] The first capacitor 31 is connected between connection part 21C and connection part 22C. The second capacitor 32 is connected in parallel to the switch unit 22. An intermediate conductive path 85 is connected to the unit connection part 25 between the switch unit 21 and the switch unit 22.

[0028] The first capacitor 31 and the second capacitor 32 are connected in series between the first conductive path 81 and the ground 80 when the first switches 21A and 22A of each switch unit 21 and 22 are ON, and the second switches 21B and 22B of each switch unit 21 and 22 are OFF. The first capacitor 31 and the second capacitor 32 are connected in parallel between the first conductive path 81 and the ground 80 when the first switches 21A and 22A of each switch unit 21 and 22 are OFF, and the second switches 21B and 22B of each switch unit 21 and 22 are ON.

[0029] The first step-down circuit 20 performs a first step-down operation by alternately switching the on and off states of the first switches 21A, 22A and the second switches 21B, 22B of each switch unit 21, 22, thereby stepping down the voltage applied to the first conductive path 81 and outputting it to the intermediate conductive path 85.

[0030] The second step-down circuit 50 has a step-down chopper circuit 51 that steps down the voltage applied to the intermediate conductive path 85 and outputs it to the second conductive path 82. The step-down chopper circuit 51 steps down the voltage output from the first step-down circuit 20 to the intermediate conductive path 85 and outputs it to the second conductive path 82. The step-down chopper circuit 51 has a high-side switch 52, a low-side switch 53, a coil 54, and an output capacitor 55.

[0031] The high-side switch 52 and the low-side switch 53 are connected in series between the intermediate conductive path 85 and the ground 80. The high-side switch 52 and the low-side switch 53 switch between an ON state, which allows bidirectional current flow through them, and an OFF state, which restricts bidirectional current flow through them. In this embodiment, the high-side switch 52 and the low-side switch 53 are composed of N-channel MOSFETs, but they may be composed of other switches.

[0032] Coil 54 is connected between node 56, which is between the high-side switch 52 and the low-side switch 53, and the second conductive path 82. Output capacitor 55 is connected between the second conductive path 82 and ground 80.

[0033] The step-down chopper circuit 51 performs a second step-down operation by alternately switching the on and off states of the high-side switch 52 and the low-side switch 53, thereby stepping down the voltage applied to the intermediate conductive path 85 and outputting it to the second conductive path 82.

[0034] The control unit 70 is configured to include, for example, a microcomputer. The control unit 70 includes, for example, a processor such as a CPU and memory such as ROM or RAM. The control unit 70 controls the first step-down circuit 20 and the second step-down circuit 50. The control unit 70 performs a first control to cause the first step-down circuit 20 to perform a first step-down operation by alternately switching the on and off states of the first switches 21A, 22A and the second switches 21B, 22B. The control unit 70 performs a second control to cause the second step-down circuit 50 to perform a second step-down operation by alternately switching the on and off states of the high-side switch 52 and the low-side switch 53. The control unit 70 performs the first control and the second control in parallel.

[0035] The control unit 70 performs the processing shown in Figure 2, for example. First, the control unit 70 determines whether the start condition has been met (step S11). The start condition may be, for example, the vehicle's start switch being switched to the ON state, or the condition for starting power supply to the load being met, or other conditions. The start switch may be, for example, an ignition switch or a power switch.

[0036] If the control unit 70 determines that the start condition is not met (No in step S11), it returns to the process in step S11. In other words, the control unit 70 repeatedly performs the process in step S11 until it determines that the start condition is met. If the control unit 70 determines that the start condition is met (Yes in step S11), it starts the first control (step S12) and then starts the second control (step S13). As a result, the control unit 70 performs the first and second controls in parallel.

[0037] In the first control, the control unit 70 controls the on / off state of the first switches 21A, 22A and the second switches 21B, 22B at a first switching frequency. The control unit 70 controls the on / off state of the high-side switch 52 and the low-side switch 53 at a second switching frequency. The first switching frequency is lower than the second switching frequency.

[0038] After starting the first and second control, the control unit 70 determines whether or not the stop condition has been met (step S14). The stop condition may be, for example, the vehicle's start switch being turned off, or the condition for stopping the power supply to the load being met, or any other condition.

[0039] If the control unit 70 determines that the stop condition is not met (No in step S14), it returns to the process in step S14. In other words, the control unit 70 repeatedly performs the process in step S14 until it determines that the stop condition has been met. During this time, the control unit 70 continues to perform the first control and the second control.

[0040] If the control unit 70 determines that the stop condition has been met (Yes in step S14), it stops the first control and the second control (step S15).

[0041] As described above, the voltage converter 10 can step down the voltage applied to the first conductive path 81 and output it to the intermediate conductive path 85 by the control unit 70 performing first control. Furthermore, the voltage converter 10 can step down the voltage applied to the intermediate conductive path 85 and output it to the second conductive path 82 by the control unit 70 performing second control. Moreover, when performing second control, the control unit 70 can adjust the output voltage by adjusting the on-duty cycle of the high-side switch 52 of the step-down chopper circuit 51. Note that the on-duty cycle is the ratio of the on-time to the switching period.

[0042] The first switching frequency when the control unit 70 switches the on / off states of the first switches 21A, 22A and the second switches 21B, 22B is smaller than the second switching frequency when the control unit 70 switches the on / off states of the high-side switch 52 and the low-side switch 53. With this configuration, the switching losses of the first switches 21A, 22A and the second switches 21B, 22B are reduced, and the step-down chopper circuit 51 can be made smaller.

[0043] Furthermore, with this configuration, no inductor is connected between the switches of the first step-down circuit 20 that constitutes the switched-capacitor converter. In a configuration where an inductor is connected between the switches, the inductor needs to be placed close to the switches, which tends to concentrate heat generation. In contrast, in the voltage converter 10, since no inductor is connected between the switches, it is easier to avoid the concentration of heat generation.

[0044] 2. Second Embodiment In the second embodiment, a configuration in which the voltage stepped down in the first step-down circuit is output to the intermediate conductive path and the third conductive path will be described. In the second embodiment, the same reference numerals are used for components that are the same as in the first embodiment, and detailed explanations are omitted.

[0045] Figure 3 shows a voltage converter 210 of the second embodiment. The voltage converter 210 includes a first step-down circuit 220 instead of the first step-down circuit 20 described in the first embodiment. The first step-down circuit 220 includes a third capacitor 33 and an inductor 34 in addition to the configuration of the first step-down circuit 20 described in the first embodiment.

[0046] The inductor 34 is connected between the connection part 22C and the third conductive path 83. The third conductive path 83 may or may not be connected to the intermediate conductive path 85. The third capacitor 33 is connected between the third conductive path 83 and ground 80.

[0047] In the second embodiment, the voltage converter 210 can step down the voltage applied to the first conductive path 81 and output it to the intermediate conductive path 85 and the third conductive path 83 by the control unit 70 performing first control. Furthermore, the control unit 70 can adjust the voltage output to the third conductive path 83 by adjusting the on-duty cycle of the first switches 21A and 22A.

[0048] Furthermore, the control unit 70 controls the first step-down circuit 220 and the second step-down circuit 50 so that the current output to the third conductive path 83 is smaller than the current output to the second conductive path 82. Specifically, the control unit 70 sets the on-duty cycles of the first switches 21A and 22A and the high-side switch 52 of the second step-down circuit 50 so that the current output to the third conductive path 83 is smaller than the current output to the second conductive path 82. Both the current output to the second conductive path 82 and the current flowing through the third conductive path 83 flow through the switch unit 21. Consequently, the first step-down circuit 220 generates more heat than the second step-down circuit 50. In this respect, with the above configuration, the current output to the third conductive path 83 is smaller than the current output to the second conductive path 82. Therefore, the difference in the amount of heat generated by the first step-down circuit 220 and the second step-down circuit 50 can be reduced.

[0049] Furthermore, the first switching frequency when the control unit 70 switches the on / off states of the first switches 21A, 22A and the second switches 21B, 22B is smaller than the second switching frequency when the control unit 70 switches the on / off states of the high-side switch 52 and the low-side switch 53. As a result, the switching losses of the first switches 21A, 22A and the second switches 21B, 22B are reduced, and the heat generation of the first step-down circuit 220 is suppressed. In other words, with this configuration, the difference in the amount of heat generated by the first step-down circuit 220 and the second step-down circuit 50 can be reduced. In addition, the step-down chopper circuit 51 can be miniaturized.

[0050] Furthermore, Figure 4 shows a configuration in which two switched-capacitor converters 100 are connected in parallel. The voltage converter 210 of the second embodiment allows for adjustment of the output voltage while reducing the number of components compared to the configuration shown in Figure 4, and can output the same power as the configuration shown in Figure 4.

[0051] 3. Third Embodiment In the third embodiment, a configuration is described in which multiple step-down sections of the first step-down circuit and the second step-down circuit in the second embodiment are provided and arranged in parallel. In the third embodiment, the same reference numerals are used for components that are the same as in the first embodiment, and detailed explanations are omitted.

[0052] Figure 5 shows a voltage converter 310 of the third embodiment. The voltage converter 310 includes a first step-down circuit 320 instead of the first step-down circuit 220 described in the second embodiment. The first step-down circuit 320 includes two first circuit sections 41 and 42, a second capacitor 32, and a third capacitor 33. Each first circuit section 41 and 42 consists of two switch units 21 and 22, a first capacitor 31, a third capacitor 33, and an inductor 34. The two first circuit sections 41 and 42 are arranged in parallel between the first conductive path 81 and the ground 80. Each first circuit section 41 and 42 steps down the voltage applied to the first conductive path 81 and outputs it to the third conductive path 83.

[0053] Furthermore, the voltage converter 310 includes a second step-down circuit 350 instead of the second step-down circuit 50 described in the second embodiment. The second step-down circuit 350 has a step-down chopper circuit 351. The step-down chopper circuit 351 includes two second circuit sections 361 and 362 and an output capacitor 55. Each second circuit section 361 and 362 is composed of a high-side switch 52, a low-side switch 53, and a coil 54. The two second circuit sections 361 and 362 are arranged in parallel between the intermediate conductive path 85 and the ground 80. Each second circuit section 361 and 362 steps down the voltage applied to the intermediate conductive path 85 and outputs it to the second conductive path 82.

[0054] With this configuration, the output power of both the first step-down circuit 320 and the second step-down circuit 350 can be increased.

[0055] 4. Fourth Embodiment In the fourth embodiment, a configuration in which three switch units are provided in the first circuit section will be described. In the fourth embodiment, the same reference numerals are used for components that are the same as in the first embodiment, and detailed explanations are omitted.

[0056] Figure 6 shows a voltage converter 410 of the fourth embodiment. The voltage converter 410 includes a first step-down circuit 420 instead of the first step-down circuit 20 described in the first embodiment. In addition to the configuration of the first step-down circuit 20 described in the first embodiment, the first step-down circuit 420 includes a switch unit 23, a first capacitor 31B, and a second capacitor 32B.

[0057] The switch unit 23 is provided between the switch unit 22 and the ground 80. The switch unit 23 has a configuration in which a first switch 23A and a second switch 23B are connected in series between the first conductive path 81 and the ground 80. The first switch 23A is positioned closer to the first conductive path 81 than the second switch 23B. The switch unit 23 has a connection portion 23C between the first switch 23A and the second switch 23B.

[0058] The first switch 23A and the second switch 23B switch between an ON state, which allows bidirectional current flow through them, and an OFF state, which restricts bidirectional current flow through them. In this embodiment, the first switch 23A and the second switch 23B are composed of N-channel MOSFETs, but they may be composed of other switches.

[0059] The first capacitor 31B is connected between connection point 22C and connection point 23C. The second capacitor 32B is connected in parallel to the switch unit 23. The intermediate conductive path 85 is connected to the unit connection point 26 between the switch unit 22 and the switch unit 23, rather than to the unit connection point 25.

[0060] The first step-down circuit 420 outputs the voltage applied to the first conductive path 81 to the intermediate conductive path 85 by performing a first step-down operation.

[0061] According to the voltage converter 410 of the fourth embodiment, the first step-down circuit 420 can step down the voltage to a lower level.

[0062] 5. Fifth Embodiment In the fifth embodiment, a configuration is described in which three switch units are provided in the first circuit section, and the stepped-down voltage is output from two intermediate conductive paths. In the fifth embodiment, the same reference numerals are used for components that are the same as in the fourth embodiment, and detailed explanations are omitted.

[0063] Figure 7 shows a voltage converter 510 according to the fifth embodiment. The voltage converter 510 includes a second step-down circuit 550 instead of the second step-down circuit 50 described in the fourth embodiment. The second step-down circuit 550 has two step-down chopper circuits 51 and 51B. Step-down chopper circuit 51B has the same configuration as step-down chopper circuit 51.

[0064] An intermediate conductive path 85 is connected to the unit connection portion 26 between switch unit 22 and switch unit 23, and an intermediate conductive path 85B is connected to the unit connection portion 25 between switch unit 21 and switch unit 22.

[0065] The step-down chopper circuit 51 steps down the voltage applied to the intermediate conductive path 85 and outputs it to the second conductive path 82. The step-down chopper circuit 51B steps down the voltage applied to the intermediate conductive path 85B and outputs it to the second conductive path 82B.

[0066] According to the voltage converter 510 of the fifth embodiment, different voltages can be output from multiple second conductive paths 82, 82B.

[0067] <Other Embodiments> This disclosure is not limited to the embodiments described above and in the drawings. For example, any combination of the features of the embodiments described above or below is possible as long as it does not contradict each other. Furthermore, any feature of the embodiments described above or below may be omitted unless explicitly stated as essential. In addition, the embodiments described above may be modified as follows.

[0068] In each of the above embodiments, the low-side switch of the buck chopper circuit may be replaced with a diode. In other words, the buck chopper circuit may operate using a diode rectification method.

[0069] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, but is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0070] 10... Voltage converter 20...First step-down circuit 21…Switch Unit 21A…First switch 21B...Second switch 21C…Connection part 22…Switch Unit 22A…First switch 22B...Second switch 22C...Connection part 23…Switch Unit 23A…First switch 23B...Second switch 23C…Connection part 25...Unit connection part 26... Unit connection part 31…First capacitor 31B...First capacitor 32...Second capacitor 32B...Second capacitor 33…Third capacitor 34…Inductor 41...1st circuit section 42...1st circuit section 50...Second step-down circuit 51... Step-down chopper circuit 51B... Step-down chopper circuit 52... High-side switch 53... Low-side switch 54... Coil 55…Output Capacitor 56...nodes 70... Control Unit 80... Grand 81...First conductive path 82...Second conductive circuit 82B…Second conductive path 83...Third conductive circuit 85…Intermediate conductive path 85B...Intermediate conductive path 100... Switched Capacitor Converter 210... Voltage converter 220...First step-down circuit 310... Voltage converter 320...First step-down circuit 350...Second step-down circuit 361…Second circuit section 362…Second circuit section 410... Voltage converter 420...First step-down circuit 510...Voltage converter 550...Second step-down circuit

Claims

1. A first step-down circuit that steps down the voltage applied to the first conductive path and outputs it to the intermediate conductive path, A second step-down circuit that steps down the voltage applied to the intermediate conductive path and outputs it to the second conductive path, The system comprises a control unit that controls the first step-down circuit and the second step-down circuit, The first step-down circuit is, N switch units (where N is a natural number greater than or equal to 2) are configured by connecting a first switch and a second switch in series, N-1 first capacitors, It has N-1 second capacitors, The N switch units are arranged in series between the first conductive path and ground. In each of the aforementioned switch units, the first switch is positioned on the first conductive path side of the second switch. Each of the switch units has a connection portion between the first switch and the second switch, Each of the first capacitors is connected between the connection portions of adjacent switch units. Each of the second capacitors is connected in parallel to the second and subsequent switch units from the first conductive path side. The intermediate conductive path is connected to at least one of the unit connection parts between each of the switch units. The second step-down circuit is, The circuit includes a step-down chopper circuit that steps down the voltage applied to the intermediate conductive path and outputs it to the second conductive path. Voltage converter.

2. The step-down chopper circuit has a high-side switch, The switching frequency when the control unit switches the on / off state of the first switch and the second switch is smaller than the switching frequency when the control unit switches the on / off state of the high-side switch. The voltage conversion device according to claim 1.

3. It comprises an inductor and a third capacitor, The inductor is connected between the ground-side end of the first capacitor and the third conductive path. The third capacitor is connected between the third conductive path and the ground. The voltage conversion device according to claim 1.

4. The control unit controls the first step-down circuit and the second step-down circuit so that the current output to the third conductive path is less than the current output to the second conductive path. The voltage conversion device according to claim 3.

5. The step-down chopper circuit has a high-side switch, The switching frequency when the control unit switches the on / off state of the first switch and the second switch is smaller than the switching frequency when the control unit switches the on / off state of the high-side switch. The voltage conversion device according to claim 3 or claim 4.

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