Power conversion device

Abstract

The embodiment relates to a power conversion device. A power conversion device according to an embodiment of the present invention is provided with a plurality of non-insulated DC-DC converter circuits including bidirectional elements, the inputs of the plurality of non-insulated DC-DC converter circuits being connected in parallel, and the outputs of the plurality of non-insulated DC-DC converter circuits being connected in series. Further, another power conversion device according to the present embodiment is provided with a plurality of non-insulated DC-DC converter circuits including bidirectional elements, the inputs of the plurality of non-insulated DC-DC converter circuits being connected in series, and the outputs of the plurality of non-insulated DC-DC converter circuits being connected in parallel.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on Japanese Patent Application No. 2023-101201 (filing date: 2023 / 06 / 20) and claims the priority of the aforementioned application, and the present application incorporates the entire contents of the aforementioned application by reference. Technical Field

[0003] This embodiment relates to a power conversion device. Background Art

[0004] A power conversion device that steps up or steps down a DC input voltage and outputs a constant DC voltage is known. For example, a power conversion device using an LLC resonant converter circuit is known.

[0005] In the case of a power conversion device using an LLC resonant converter circuit, it is difficult to control the output voltage so that it remains constant over a wide range from a low output voltage to a high output voltage using the LLC resonant converter circuit alone. Therefore, it is common practice to provide a constant voltage circuit at the front stage of the LLC resonant converter circuit, first perform constant voltage control using the primary constant voltage circuit, and then perform step-up and step-down using the second stage LLC resonant converter circuit. Summary of the invention

[0006] An object of the present embodiment is to provide a power conversion device capable of controlling the output voltage to be constant over a wide range from a low output voltage to a high output voltage.

[0007] In order to solve the above-mentioned problems, the power conversion device of this embodiment includes multiple non-isolated DC-DC converter circuits including bidirectional elements, the inputs of the multiple non-isolated DC-DC converter circuits are connected in parallel, and the outputs of the multiple non-isolated DC-DC converter circuits are connected in series.

[0008] In addition, another power conversion device of the present embodiment includes multiple non-isolated DC-DC converter circuits including bidirectional elements, the inputs of the multiple non-isolated DC-DC converter circuits are connected in series, and the outputs of the multiple non-isolated DC-DC converter circuits are connected in parallel. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a diagram showing the configuration of a power conversion device according to Embodiment 1.

[0010] Figure 2 This is a diagram showing a detailed configuration of a non-insulated DC-DC converter circuit according to the first embodiment.

[0011] Figure 3This is a diagram showing an example of the time waveforms of the first PWM control signal and the second PWM control signal according to the first embodiment.

[0012] Figure 4 This is a diagram showing the on / off operation timing of each of the N non-insulated DC-DC converter circuits according to the first embodiment.

[0013] Figure 5 This is a diagram showing the configuration of a power conversion device according to the second embodiment.

[0014] Figure 6 This is a diagram showing the on / off operation timing of each of N non-insulated DC-DC converter circuits according to the second embodiment.

[0015] Figure 7 This is a diagram showing the configuration of a power conversion device according to a third embodiment.

[0016] Figure 8 This is a diagram showing a detailed configuration of a non-insulated DC-DC converter circuit according to a third embodiment.

[0017] Fig. 9 This is a diagram showing the structure of a power conversion device according to a fourth embodiment.

[0018] Fig.10 This is a diagram showing a detailed configuration of a non-insulated DC-DC converter circuit according to a fourth embodiment.

[0019] (Explanation of Reference Numerals)

[0020] 11a: first input terminal; 11b: second input terminal; 12a: first output terminal; 12b: second output terminal; 13: first bidirectional element; 13a: one terminal; 13b: the other terminal; 14: second bidirectional element; 14a: one terminal; 14b: the other terminal; 15: first voltage sensor; 16: second voltage sensor; 17: first current sensor; 18: first drive circuit; 19: second drive circuit; 20: control circuit; 100: power conversion device; 101: DC-DC converter circuit; 102: timing control circuit; 200: power conversion device; 202: timing control circuit; 300: power conversion device; 301: DC-DC converter circuit; 320: control circuit; 321: second current sensor; 400: power conversion device; 401: DC-DC converter circuit; 420: control circuit; 422: third current sensor; C1: first capacitor; C2: second capacitor; D: duty cycle; D1: first unidirectional element; D2: second unidirectional element; D3: third unidirectional element; fsw: switching frequency;

[0021] G1: 1st PWM control signal; G2: 2nd PWM control signal; L1: 1st inductor; L2: 2nd inductor; L3: 3rd inductor; M1: semiconductor switch element (1st semiconductor switch element); M2: semiconductor switch element (2nd semiconductor switch element); M3: semiconductor switch element (1st semiconductor switch element); M4: semiconductor switch element (2nd semiconductor switch element); M5: semiconductor switch element (3rd semiconductor switch element); N1: 1st node; N2: 2nd node; N3: 3rd node; N4: 4th node; N5: 5th node; N6: 6th node; I1: 1st current; I2: 2nd current; I3: 3rd current; INa: input terminal; INb: input terminal; OUTa: output terminal; OUTb: output terminal; TS: timing control signal; V1: 1st voltage; V2: 2nd voltage. DETAILED DESCRIPTION

[0022] Hereinafter, the present embodiment will be described with reference to the drawings. In the drawings, the same or corresponding elements are denoted by the same reference numerals, and detailed descriptions thereof will be appropriately omitted.

[0023] (Implementation Method 1)

[0024] Figure 1 1 is a diagram showing the structure of a power conversion device 100 according to Embodiment 1. The power conversion device 100 is a device that steps up a DC input voltage and outputs a constant DC voltage, and includes input terminals INa and INb and output terminals OUTa and OUTb. A DC input voltage Vin is applied to the input terminals INa and INb, and a DC output voltage Vo (>Vin) is output from the output terminals OUTa and OUTb.

[0025] The power conversion device 100 includes N non-insulated DC-DC converter circuits 101(1)-101(N) and a timing control circuit 102 for controlling the operation timing of the N DC-DC converter circuits 101(1)-101(N). The inputs of the DC-DC converter circuits 101(1)-101(N) are connected in parallel, one is connected to the input terminal INa, and the other is connected to the input terminal INb. The input voltages V1 of the DC-DC converter circuits 101(1)-101(N) are all equal, V1=Vin.

[0026] The outputs of the DC-DC converter circuits 101(1)-101(N) are connected in series, one output of the uppermost DC-DC converter circuit 101(1) is connected to the output terminal OUTa, and the other output of the lowermost DC-DC converter circuit 101(N) is connected to the output terminal OUTb. The output voltages V2 of the DC-DC converter circuits 101(1)-101(N) are all equal, and therefore, V2×N=Vo.

[0027] Figure 2 1 is a diagram showing a detailed structure of a non-insulated DC-DC converter circuit 101 according to Embodiment 1. Since the DC-DC converter circuits 101 ( 1 ) to 101 (N) all have the same structure, they are collectively referred to as the DC-DC converter circuit 101 .

[0028] The DC-DC converter circuit 101 includes: a first input terminal 11a and a second input terminal 11b; a first output terminal 12a and a second output terminal 12b; a first bidirectional element 13, which is arranged between the first input terminal 11a and the first output terminal 12a; and a second bidirectional element 14, which is arranged between the second input terminal 11b and the second output terminal 12b.

[0029] The first bidirectional element 13 includes semiconductor switch elements M1 and M2. As the semiconductor switch elements M1 and M2, for example, N-channel MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) can be used. In this case, the source terminals of the semiconductor switch elements M1 and M2 are connected to each other, and the gate terminals are connected to each other. The drain terminal of the semiconductor switch element M1 is connected to one terminal 13a of the first bidirectional element 13, and the drain terminal of the semiconductor switch element M2 is connected to the other terminal 13b of the first bidirectional element 13.

[0030] When the control signal G1 supplied to the first bidirectional element 13 is turned on, the first bidirectional element 13 is bidirectionally conducted, that is, current can flow in the right direction in the figure through the channel between the drain and source of the semiconductor switch element M1 and the parasitic diode of the semiconductor switch element M2, and current can also flow in the left direction in the figure through the channel between the drain and source of the semiconductor switch element M2 and the parasitic diode of the semiconductor switch element M1.

[0031] When the control signal G1 supplied to the first bidirectional element 13 is OFF, current does not flow in any direction of the first bidirectional element 13. That is, the potential of one terminal 13a of the first bidirectional element 13 is electrically separated from the potential of the other terminal 13b.

[0032] The second bidirectional element 14 includes semiconductor switch elements M3 and M4. As the semiconductor switch elements M3 and M4, for example, N-channel MOSFETs can be used. In this case, the source terminals of the semiconductor switch elements M3 and M4 are connected to each other and the gate terminals are connected to each other. The drain terminal of the semiconductor switch element M3 is connected to one terminal 14a of the second bidirectional element 14, and the drain terminal of the semiconductor switch element M4 is connected to the other terminal 14b of the second bidirectional element 14.

[0033] When the control signal G2 supplied to the second bidirectional element 14 is turned on, the second bidirectional element 14 is bidirectionally conductive. That is, current can flow in the right direction in the figure through the channel between the drain and source of the semiconductor switch element M3 and the parasitic diode of the semiconductor switch element M4, and current can also flow in the left direction in the figure through the channel between the drain and source of the semiconductor switch element M4 and the parasitic diode of the semiconductor switch element M3.

[0034] When the control signal G2 supplied to the second bidirectional element 14 is OFF, current does not flow in any direction of the second bidirectional element 14. That is, the potential of one terminal 14a of the second bidirectional element 14 is electrically separated from the potential of the other terminal 14b.

[0035] In addition, the DC-DC converter circuit 101 includes a first inductor L1, a first unidirectional element D1, and a second unidirectional element D2. One end of the first inductor L1 is connected to a first node N1 between the first bidirectional element 13 and the first output terminal 12a, and the other end of the first inductor L1 is connected to a second node N2 between the second bidirectional element 14 and the second output terminal 12b.

[0036] As the first unidirectional element D1, for example, a semiconductor diode can be used. In this case, the anode of the first unidirectional element D1 is connected to the first output terminal 12a, and the cathode of the first unidirectional element D1 is connected to the first node N1.

[0037] As the second unidirectional element D2, for example, a semiconductor diode can be used. In this case, the anode of the second unidirectional element D2 is connected to the second node N2, and the cathode of the second unidirectional element D2 is connected to the second output terminal 12b.

[0038] The DC-DC converter circuit 101 includes a first capacitor C1 and a second capacitor C2. The first capacitor C1 is connected between the first input terminal 11a and the second input terminal 11b. The second capacitor C2 is connected between the first output terminal 12a and the second output terminal 12b.

[0039] The DC-DC converter circuit 101 further includes a first voltage sensor 15 , a second voltage sensor 16 , a first current sensor 17 , a first drive circuit 18 , a second drive circuit 19 , and a control circuit 20 .

[0040] The first voltage sensor 15 detects an input voltage V1 (first voltage) of the DC-DC converter circuit 101. The second voltage sensor 16 detects an output voltage V2 (second voltage) of the DC-DC converter circuit 101. The first current sensor 17 detects a first current I1 flowing through the first inductor L1.

[0041] The first drive circuit 18 supplies the first PWM control signal G1 to the first bidirectional element 13. The second drive circuit 19 supplies the second PWM control signal G2 to the second bidirectional element 14. The control circuit 20 controls the operation of the first drive circuit 18 and the second drive circuit 19 based on the timing control signal TS input from the timing control circuit 102, the input voltage V1, the output voltage V2, and the first current I1.

[0042] Figure 3 1 is a diagram showing an example of the time waveform of the first PWM control signal G1 and the second PWM control signal G2. The first PWM control signal G1 and the second PWM control signal G2 are controlled to have the same waveform that changes at the same timing. That is, when the first PWM control signal G1 is turned on, the second PWM control signal G2 is also turned on, and when the first PWM control signal G1 is turned off, the second PWM control signal G2 is also turned off. However, the voltage level of the first PWM control signal G1 is different from the voltage level of the second PWM control signal, and the GNDs of the two are separated.

[0043] When the first PWM control signal G1 and the second PWM control signal G2 are both turned on, the first bidirectional element 13 and the second bidirectional element 14 are both turned on. At this time, current flows along the path of the first input terminal 11a, the first bidirectional element 13, the first inductor L1, the second bidirectional element 14 and the second input terminal 11b, and magnetic energy is accumulated in the first inductor L1 due to the current.

[0044] When the first PWM control signal G1 and the second PWM control signal G2 are both turned off, the first bidirectional element 13 and the second bidirectional element 14 are both in a non-conductive state. At this time, due to the magnetic energy accumulated in the first inductor L1, the current flows along the path of the first inductor L1, the second unidirectional element D2, the second output terminal 12b, the first output terminal 12a, and the first unidirectional element D1.

[0045] The control circuit 20 can control the output voltage V2 of the DC-DC converter circuit 101 to be constant by appropriately adjusting the duty ratio D (0<D<1) of the first PWM control signal G1 and the second PWM control signal G2 .

[0046] For example, when input voltage V1<output voltage V2, the DC-DC converter circuit 101 functions as a step-up converter circuit. Also, for example, when input voltage V1>output voltage V2, the DC-DC converter circuit 101 functions as a step-down converter circuit.

[0047] Figure 4 This is a diagram showing the operation timing of each on / off of N non-insulated DC-DC converter circuits 101(1)-101(N) of this embodiment 1. The timing control circuit 102 controls the operation of the N DC-DC converter circuits 101(1)-101(N) by repeating N time slots TS_1-TS_N. In addition, in the figure, fsw is the switching frequency.

[0048] In the first time slot TS_1, only the first bidirectional element 13 and the second bidirectional element 14 of the first DC-DC converter circuit 101 (1) are turned off, and the first bidirectional elements 13 and the second bidirectional elements 14 of the other N-1 DC-DC converter circuits are all turned on.

[0049] In the second time slot TS_2, only the first bidirectional element 13 and the second bidirectional element 14 of the second DC-DC converter circuit 101 (2) are turned off, and the first bidirectional elements 13 and the second bidirectional elements 14 of the other N-1 DC-DC converter circuits are all turned on.

[0050] Similarly, in the Nth time slot TS_N, only the first bidirectional element 13 and the second bidirectional element 14 of the Nth DC-DC converter circuit 101 (N) are turned off, and the first bidirectional elements 13 and the second bidirectional elements 14 of the other N-1 DC-DC converter circuits are all turned on.

[0051] In the first embodiment, the transformation ratios V2 / V1 of the DC-DC converter circuits 101(1)-101(N) are all equal, namely D / (1-D). Therefore, the relationship between the input voltage Vin and the output voltage Vo of the power conversion device 100 formed by connecting N DC-DC converter circuits 101(1)-101(N) is expressed as follows.

[0052] [Formula 1]

[0053]

[0054] As described above, the power conversion device 100 of the first embodiment includes a plurality of non-insulated DC-DC converter circuits 101 including bidirectional elements, the inputs of the DC-DC converter circuits 101 are connected in parallel, and the outputs of the DC-DC converter circuits 101 are connected in series.

[0055] As described above, for example, in the case of a conventional power conversion device using an LLC resonant converter circuit, it is difficult to control the output voltage to be constant in a wide range from a low output voltage to a high output voltage by the LLC resonant converter circuit alone. Therefore, it is common practice to provide a constant voltage circuit at the front stage of the LLC resonant converter circuit, first perform constant voltage control by the primary constant voltage circuit, and then perform step-up and step-down by the second stage LLC resonant converter circuit.

[0056] In contrast, in the power conversion device 100 of the first embodiment, by connecting a plurality of non-insulated DC-DC converter circuits 101 having both constant voltage control function and step-up / step-down function, the output voltage V2 can be controlled in a constant manner in a wide range from low output voltage to high output voltage by a simpler circuit structure than the conventional technology. In addition, by adjusting the number of DC-DC converter circuits 101, any output voltage V2 can be obtained, so the scalability is excellent.

[0057] In addition, in the power conversion device 100 of the present embodiment 1, a high transformation ratio is achieved not by a single DC-DC converter circuit, but by connecting a plurality of DC-DC converter circuits 101. Therefore, the transformation ratio of each DC-DC converter circuit 101 can be low. Thus, by appropriately adjusting the number N of DC-DC converter circuits 101, the duty cycle D of each DC-DC converter circuit 101 can be set to about 0.5, and the on / off time of the PWM control of each DC-DC converter circuit 101 can have a margin. Thus, it becomes easy to increase the switching frequency fsw to a high frequency, and the first inductor L1 can be relatively small.

[0058] In addition, the on / off operation of the non-insulated DC-DC converter circuit 101 of the first embodiment can be controlled by PWM control similar to that of a general buck-boost chopper circuit. In addition, components such as a transformer and a buffer required in a conventional non-insulated flyback circuit are not required. As a result, design and control become very easy.

[0059] In addition, the non-insulated DC-DC converter circuit 101 of the first embodiment includes a first bidirectional element 13 and a second bidirectional element 14. The first bidirectional element 13 is composed of two semiconductor switch elements M1 and M2. The second bidirectional element 14 is composed of two semiconductor switch elements M3 and M4. In the off state of the DC-DC converter circuit 101, the input potential and the output potential are electrically separated due to the parasitic capacitance between the drain and the source of the semiconductor switch element.

[0060] In contrast, in the conventional LLC resonant converter circuit, the input potential and the output potential in the on state and the off state are electrically separated by a high-frequency transformer. The high-frequency transformer is a component that occupies a large area on the circuit and may also become a cause of increasing the man-hours required for circuit design. In the non-insulated DC-DC converter circuit 101 of the first embodiment, there is no need to use a high-frequency transformer, so it can be expected that the circuit area can be miniaturized and the man-hours required for design can be shortened.

[0061] (Implementation Method 2)

[0062] Figure 5 1 is a diagram showing the structure of a power conversion device 200 according to Embodiment 2. The power conversion device 200 is a device that steps down a DC input voltage and outputs a constant DC voltage. A DC input voltage Vin is applied to input terminals INa and INb, and a DC output voltage Vo (<Vin) is output from output terminals OUTa and OUTb.

[0063] The power conversion device 200 includes N non-insulated DC-DC converter circuits 101 (1) to 101 (N) having the same structure as that of the above-mentioned Embodiment 1. In addition, the power conversion device 200 includes a timing control circuit 202 that controls the operation timing of the N DC-DC converter circuits 101 (1) to 101 (N).

[0064] The inputs of the DC-DC converter circuits 101(1)-101(N) are connected in series, one input of the uppermost DC-DC converter circuit 101(1) is connected to the input terminal INa, and the other input of the lowermost DC-DC converter circuit 101(N) is connected to the input terminal INb. The input voltages V1 of the DC-DC converter circuits 101(1)-101(N) are all equal, and therefore, V1=Vin / N.

[0065] The outputs of the DC-DC converter circuits 101(1)-101(N) are connected in parallel, one connected to the output terminal OUTa and the other connected to the output terminal OUTb. The output voltages V2 of the DC-DC converter circuits 101(1)-101(N) are all equal, V2=Vo.

[0066] Figure 6 This is a diagram showing the on / off operation timing of each of the N non-insulated DC-DC converter circuits 101 ( 1 )- 101 (N) according to Embodiment 2. The timing control circuit 202 controls the operation of the N DC-DC converter circuits 101 ( 1 )- 101 (N) by repeating N time slots TS_1-TS_N.

[0067] In the first time slot TS_1, only the first bidirectional element 13 and the second bidirectional element 14 of the first DC-DC converter circuit 101 (1) are turned on, and the first bidirectional elements 13 and the second bidirectional elements 14 of the other N-1 DC-DC converter circuits are all turned off.

[0068] In the second time slot TS_2, only the first bidirectional element 13 and the second bidirectional element 14 of the second DC-DC converter circuit 101 (2) are turned on, and the first bidirectional elements 13 and the second bidirectional elements 14 of the other N-1 DC-DC converter circuits are all turned off.

[0069] Similarly, in the Nth time slot TS_N, only the first bidirectional element 13 and the second bidirectional element 14 of the Nth DC-DC converter circuit 101 (N) are turned on, and the first bidirectional elements 13 and the second bidirectional elements 14 of the other N-1 DC-DC converter circuits are all turned off.

[0070] In the second embodiment, the transformation ratios V2 / V1 of the DC-DC converter circuits 101(1)-101(N) are all equal, namely D / (1-D). In this case, the relationship between the input voltage Vin and the output voltage Vo of the power conversion device 200 formed by connecting N DC-DC converter circuits 101(1)-101(N) is expressed as follows.

[0071] [Formula 2]

[0072]

[0073] As described above, the power conversion device 200 of the second embodiment includes a plurality of non-insulated DC-DC converter circuits 101 including bidirectional elements, the inputs of the DC-DC converter circuits 101 are connected in series, and the outputs of the DC-DC converter circuits 101 are connected in parallel. Thus, the power conversion device 200 of the second embodiment can obtain the same effect as the above-mentioned first embodiment.

[0074] (Implementation method 3)

[0075] Figure 7 1 is a diagram showing the structure of a power conversion device 300 according to Embodiment 3. The power conversion device 300 is a device obtained by replacing the N non-insulated DC-DC converter circuits 101-101(N) in the power conversion device 100 according to Embodiment 1 with N non-insulated DC-DC converter circuits 301(1)-301(N). The power conversion device 300 boosts the input voltage of the direct current and outputs a constant direct current voltage. The operation timing of each on / off of the DC-DC converter circuits 301(1)-301(N) is the same as that of Embodiment 1.

[0076] Figure 8 1 is a diagram showing a detailed structure of a non-insulated DC-DC converter circuit 301 according to Embodiment 3. Since the structures of the DC-DC converter circuits 301 ( 1 ) to 301 (N) are all the same, they are collectively referred to as the DC-DC converter circuit 301 .

[0077] The DC-DC converter circuit 301 includes a first bidirectional element 13 provided between the first input terminal 11 a and the first output terminal 12 a , and a second bidirectional element 14 provided between the second input terminal 11 b and the second output terminal 12 b .

[0078] The DC-DC converter circuit 301 includes a second inductor L2, a second current sensor 321, and a semiconductor switch element M5. The second inductor L2 is connected between the first input terminal 11a and the first bidirectional element 13. The second current sensor 321 detects a second current I2 flowing through the second inductor L2.

[0079] As the semiconductor switch element M5, for example, an N-channel MOSFET can be used. In this case, the drain terminal of the semiconductor switch element M5 is connected to the third node N3 between the second inductor L2 and the first bidirectional element 13, and the source terminal of the semiconductor switch element M5 is connected to the fourth node N4 between the second input terminal 11b and the second bidirectional element 14.

[0080] The control circuit 220 controls the operations of the first drive circuit 18 and the second drive circuit 19 based on the timing control signal TS input from the timing control circuit 102 , the input voltage V1 , the output voltage V2 , and the second current I2 .

[0081] In the third embodiment, the transformation ratio V2 / V1 of the DC-DC converter circuits 301(1)-301(N) is all equal to 1 / (1-D). Therefore, V2>V1 is always satisfied. The relationship between the input voltage Vin and the output voltage Vo of the power conversion device 300 is as follows.

[0082] [Formula 3]

[0083]

[0084]

[0085] (Implementation 4)

[0086] Fig. 9 1 is a diagram showing the structure of a power conversion device 400 according to a fourth embodiment. The power conversion device 400 is a device obtained by replacing the N non-insulated DC-DC converter circuits 101-101(N) in the power conversion device 200 according to the second embodiment with N non-insulated DC-DC converter circuits 401(1)-401(N). The power conversion device 400 steps down the input voltage of the direct current and outputs a constant direct current voltage. The operation timing of each on / off of the DC-DC converter circuits 401(1)-401(N) is the same as that of the second embodiment.

[0087] Fig.10 1 is a diagram showing a detailed structure of a non-insulated DC-DC converter circuit 401 according to Embodiment 4. Since the DC-DC converter circuits 401 ( 1 ) to 401 (N) all have the same structure, they are collectively referred to as the DC-DC converter circuit 401 .

[0088] The DC-DC converter circuit 401 includes a first bidirectional element 13 provided between the first input terminal 11 a and the first output terminal 12 a , and a second bidirectional element 14 provided between the second input terminal 11 b and the second output terminal 12 b .

[0089] The DC-DC converter circuit 401 includes a third inductor L3, a third current sensor 422, and a third unidirectional element D3. The third inductor L3 is connected between the first bidirectional element 13 and the first output terminal 12a. The third current sensor 422 detects a third current I3 flowing through the third inductor L3.

[0090] As the third unidirectional element D3, for example, a semiconductor diode can be used. In this case, the cathode of the third unidirectional element D3 is connected to the fifth node N5 between the first bidirectional element 13 and the third inductor L3, and the anode of the third unidirectional element D3 is connected to the sixth node N6 between the second bidirectional element 14 and the second output terminal 12b.

[0091] The control circuit 420 controls the operations of the first drive circuit 18 and the second drive circuit 19 based on the timing control signal TS input from the timing control circuit 202 , the input voltage V1 , the output voltage V2 , and the third current I3 .

[0092] In the fourth embodiment, the transformation ratio V2 / V1 of the DC-DC converter circuits 401(1)-401(N) is all equal to D. Therefore, V2<V1 is always satisfied. The relationship between the input voltage Vin and the output voltage Vo of the power conversion device 400 is as follows.

[0093] [Formula 4]

[0094]

[0095]

[0096] (Variation Example)

[0097] In the above-mentioned Embodiments 1 to 4, N-channel MOSFETs are used as the semiconductor switch elements M1 to M5. Alternatively, P-channel MOSFETs may be used as the semiconductor switch elements M1 to M5.

[0098] In the above-mentioned embodiments 1-4, semiconductor diodes are used as unidirectional elements D1-D3. Alternatively, as unidirectional elements D1-D3, synchronous rectification can be performed by using semiconductor switch elements such as MOSFET. Alternatively, as unidirectional elements D1-D3, a structure in which two semiconductor switch elements similar to the bidirectional elements 13 or 14 are connected can be used. In this way, the heat generation of the unidirectional elements D1-D3 can be suppressed.

[0099] In addition, the semiconductor switch element is not limited to MOSFET. For example, as the semiconductor switch element, IGBT (Insulated Gate Bipolar Transistor) or BJT (Bipolar Junction Transistor) can be used. In addition, as the semiconductor constituting the semiconductor switch element and the semiconductor diode, various materials such as Si (Silicon), SiC (Silicon Carbide) or GaN (Gallium Nitride) can be used.

[0100] Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the embodiments. These embodiments can be implemented in various other ways, and various omissions, substitutions, changes, combinations, etc. can be made without departing from the scope of the subject matter of the embodiments. These embodiments and their variations are included in the scope and subject matter of the embodiments, and are included in the scope of the claims and their equivalents.

[0101] In addition, this embodiment may also have the following structure.

[0102] [Technical Solution 1] (Implementation Method 1, Implementation Method 3)

[0103] A power conversion device includes a plurality of non-insulated DC-DC converter circuits including bidirectional elements.

[0104] Inputs of the plurality of non-insulated DC-DC converter circuits are connected in parallel, and outputs of the plurality of non-insulated DC-DC converter circuits are connected in series.

[0105] [Technical Solution 2] (Implementation Method 1, Implementation Method 3)

[0106] According to the power conversion device of technical solution 1, the plurality of non-insulated DC-DC converter circuits respectively include:

[0107] A first input terminal and a second input terminal;

[0108] a first output terminal and a second output terminal;

[0109] a first bidirectional element disposed between the first input terminal and the first output terminal; and

[0110] The second bidirectional element is provided between the second input terminal and the second output terminal.

[0111] [Technical Solution 3] (Implementation Method 1, Implementation Method 3)

[0112] According to the power conversion device of technical solution 2, the first bidirectional element and the second bidirectional element include a first semiconductor switch element and a second semiconductor switch element, respectively.

[0113] The first terminals of the first semiconductor switch element and the second semiconductor switch element are connected to each other, and the control terminals of the first semiconductor switch element and the second semiconductor switch element are connected to each other.

[0114] [Technical Solution 4] (Implementation Method 1)

[0115] According to the power conversion device of technical solution 2 or 3, the plurality of non-insulated DC-DC converter circuits respectively further include:

[0116] The first inductor has one end connected to a first node between the first bidirectional element and the first output terminal, and the other end connected to a second node between the second bidirectional element and the second output terminal.

[0117] [Technical Solution 5] (Implementation Method 1)

[0118] According to the power conversion device of technical solution 4, wherein the plurality of non-insulated DC-DC converter circuits respectively further include:

[0119] a first unidirectional element having one end connected to the first output terminal and the other end connected to the first node; and

[0120] The second unidirectional element has one end connected to the second node and the other end connected to the second output terminal.

[0121] [Technical Solution 6] (Implementation Method 1)

[0122] According to any one of technical solutions 2 to 5, the power conversion device, wherein the plurality of non-insulated DC-DC converter circuits respectively further include:

[0123] a first driving circuit for supplying a first PWM control signal to the first bidirectional element;

[0124] a second driving circuit for supplying a second PWM control signal to the second bidirectional element; and

[0125] The control circuit controls the operations of the first drive circuit and the second drive circuit.

[0126] [Technical Solution 7] (Implementation Method 1)

[0127] According to the power conversion device of technical solution 6, wherein the plurality of non-insulated DC-DC converter circuits respectively further include:

[0128] a first voltage sensor for detecting a first voltage between the first input terminal and the second input terminal;

[0129] a second voltage sensor for detecting a second voltage between the first output terminal and the second output terminal; and

[0130] a first current sensor for detecting a first current flowing through the first inductor;

[0131] The control circuit controls operations of the first drive circuit and the second drive circuit based on the first voltage, the second voltage, and the first current.

[0132] [Technical Solution 8] (Implementation Method 1)

[0133] According to the power conversion device of technical solution 7, the number of the plurality of non-insulated DC-DC converter circuits is N, and the power conversion device further comprises a timing control circuit for controlling the operation timing of the N DC-DC converter circuits by repeating N time slots.

[0134] In the first time slot, only the first DC-DC converter circuit is turned off, and the other N-1 DC-DC converter circuits are all turned on.

[0135] In the second time slot, only the second DC-DC converter circuit is turned off, and the other N-1 DC-DC converter circuits are all turned on.

[0136] The same control is then applied.

[0137] [Technical Solution 9] (Implementation Method 3)

[0138] According to the power conversion device of technical solution 2 or 3, the plurality of non-insulated DC-DC converter circuits respectively further include:

[0139] a second inductor connected between the first input terminal and the first bidirectional element; and

[0140] The third switching element has one end connected to a third node between the second inductor and the first bidirectional element, and the other end connected to a fourth node between the second input terminal and the second bidirectional element.

[0141] [Technical Solution 10] (Implementation Method 2, Implementation Method 4)

[0142] A power conversion device includes a plurality of non-insulated DC-DC converter circuits including bidirectional elements.

[0143] Inputs of the plurality of non-insulated DC-DC converter circuits are connected in series, and outputs of the plurality of non-insulated DC-DC converter circuits are connected in parallel.

[0144] [Technical Solution 11] (Implementation Method 2, Implementation Method 4)

[0145] According to the power conversion device of technical solution 10, the plurality of non-insulated DC-DC converter circuits respectively include:

[0146] A first input terminal and a second input terminal;

[0147] a first output terminal and a second output terminal;

[0148] a first bidirectional element disposed between the first input terminal and the first output terminal; and

[0149] The second bidirectional element is provided between the second input terminal and the second output terminal.

[0150] [Technical Solution 12] (Implementation Method 2, Implementation Method 4)

[0151] According to the power conversion device of technical solution 11, the first bidirectional element and the second bidirectional element include a first semiconductor switch element and a second semiconductor switch element, respectively.

[0152] The first terminals of the first semiconductor switch element and the second semiconductor switch element are connected to each other, and the control terminals of the first semiconductor switch element and the second semiconductor switch element are connected to each other.

[0153] [Technical Solution 13] (Implementation Method 2)

[0154] According to the power conversion device of technical solution 11 or 12, wherein the plurality of non-insulated DC-DC converter circuits respectively further include:

[0155] The first inductor has one end connected to a first node between the first bidirectional element and the first output terminal, and the other end connected to a second node between the second bidirectional element and the second output terminal.

[0156] [Technical Solution 14] (Implementation Method 2)

[0157] According to the power conversion device of technical solution 13, wherein the plurality of non-insulated DC-DC converter circuits respectively further include:

[0158] a first unidirectional element having one end connected to the first output terminal and the other end connected to the first node; and

[0159] The second unidirectional element has one end connected to the second node and the other end connected to the second output terminal.

[0160] [Technical Solution 15] (Implementation Method 2)

[0161] According to any one of technical solutions 11 to 14, the power conversion device, wherein the plurality of non-insulated DC-DC converter circuits respectively further include:

[0162] a first driving circuit for supplying a first PWM control signal to the first bidirectional element;

[0163] a second driving circuit for supplying a second PWM control signal to the second bidirectional element; and

[0164] The control circuit controls the operations of the first drive circuit and the second drive circuit.

[0165] [Technical Solution 16] (Implementation Method 2)

[0166] According to the power conversion device of technical solution 15, wherein the plurality of non-insulated DC-DC converter circuits respectively further include:

[0167] a first voltage sensor for detecting a first voltage between the first input terminal and the second input terminal;

[0168] a second voltage sensor for detecting a second voltage between the first output terminal and the second output terminal; and

[0169] a first current sensor for detecting a first current flowing through the first inductor;

[0170] The control circuit controls operations of the first drive circuit and the second drive circuit based on the first voltage, the second voltage, and the first current.

[0171] [Technical Solution 17] (Implementation Method 2)

[0172] According to the power conversion device of technical solution 16, the number of the plurality of non-insulated DC-DC converter circuits is N, and the power conversion device further comprises a timing control circuit for controlling the operation timing of the N DC-DC converter circuits by repeating N time slots.

[0173] In the first time slot, only the first DC-DC converter circuit is turned on, and the other N-1 DC-DC converter circuits are all turned off.

[0174] In the second time slot, only the second DC-DC converter circuit is turned on, and the other N-1 DC-DC converter circuits are all turned off.

[0175] The same control is then applied.

[0176] [Technical Solution 18] (Implementation Method 4)

[0177] According to the power conversion device of technical solution 11 or 12, wherein the plurality of non-insulated DC-DC converter circuits respectively further include:

[0178] a third inductor connected between the first bidirectional element and the first output terminal; and

[0179] The third unidirectional element has one end connected to a fifth node between the first bidirectional element and the third inductor, and the other end connected to a sixth node between the second bidirectional element and the second output terminal.

Claims

1. A power conversion device comprising a plurality of non-insulated DC-DC converter circuits including bidirectional elements, Inputs of the plurality of non-insulated DC-DC converter circuits are connected in parallel, and outputs of the plurality of non-insulated DC-DC converter circuits are connected in series.

2. The power conversion device according to claim 1, in, The plurality of non-insulated DC-DC converter circuits respectively include: A first input terminal and a second input terminal; A first output terminal and a second output terminal; a first bidirectional element disposed between the first input terminal and the first output terminal; and The second bidirectional element is provided between the second input terminal and the second output terminal.

3. The power conversion device according to claim 2, in, The first bidirectional element and the second bidirectional element include a first semiconductor switch element and a second semiconductor switch element, respectively. The first terminals of the first semiconductor switch element and the second semiconductor switch element are connected to each other, and the control terminals of the first semiconductor switch element and the second semiconductor switch element are connected to each other.

4. The power conversion device according to claim 2, in, The plurality of non-insulated DC-DC converter circuits further include: The first inductor has one end connected to a first node between the first bidirectional element and the first output terminal, and the other end connected to a second node between the second bidirectional element and the second output terminal.

5. The power conversion device according to claim 4, in, The plurality of non-insulated DC-DC converter circuits further include: a first unidirectional element having one end connected to the first output terminal and the other end connected to the first node; and The second unidirectional element has one end connected to the second node and the other end connected to the second output terminal.

6. The power conversion device according to claim 4, in, The plurality of non-insulated DC-DC converter circuits further include: a first driving circuit for supplying a first PWM control signal to the first bidirectional element; a second driving circuit for supplying a second PWM control signal to the second bidirectional element; and The control circuit controls the operations of the first drive circuit and the second drive circuit.

7. The power conversion device according to claim 6, in, The plurality of non-insulated DC-DC converter circuits further include: a first voltage sensor for detecting a first voltage between the first input terminal and the second input terminal; a second voltage sensor for detecting a second voltage between the first output terminal and the second output terminal; and a first current sensor for detecting a first current flowing through the first inductor; The control circuit controls operations of the first drive circuit and the second drive circuit based on the first voltage, the second voltage, and the first current.

8. The power conversion device according to claim 7, in, The number of the plurality of non-insulated DC-DC converter circuits is N, and the power conversion device further includes a timing control circuit for controlling the operation timing of the N DC-DC converter circuits by repeating N time slots. In the first time slot, only the first DC-DC converter circuit is turned off, and the other N-1 DC-DC converter circuits are all turned on. In the second time slot, only the second DC-DC converter circuit is turned off, and the other N-1 DC-DC converter circuits are all turned on. The same control is then applied.

9. The power conversion device according to claim 2, in, The plurality of non-insulated DC-DC converter circuits further include: a second inductor connected between the first input terminal and the first bidirectional element; and The third switching element has one end connected to a third node between the second inductor and the first bidirectional element, and the other end connected to a fourth node between the second input terminal and the second bidirectional element.

10. A power conversion device comprising a plurality of non-insulated DC-DC converter circuits including bidirectional elements, Inputs of the plurality of non-insulated DC-DC converter circuits are connected in series, and outputs of the plurality of non-insulated DC-DC converter circuits are connected in parallel.

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