Power conversion device and vehicle

Abstract

To provide a power conversion device with which it is possible to switch between full-bridge operation and half-bridge operation by a simple structure.SOLUTION: A power conversion device, which performs power conversion for supplying power in both directions between a first apparatus and a second apparatus, comprises a transformer, a primary circuit, and a secondary circuit. The primary circuit has a first leg that includes two first switch elements which are connected in series via a first contact, and a second leg that includes two second switch elements which are connected in series via a second contact. A primary coil of the transformer is connected to the second contact via a capacitor. In the primary circuit, full-bridge operation is executable by alternately switching on / off of two switch elements in each leg every prescribed time, and half-bridge operation is executable by keeping one of two switch elements in the first or the second leg always turned on and keeping the other of these always turned off.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power conversion device and a vehicle. [Background technology]

[0002] In recent years, lithium-ion batteries have come to be used as chargeable and dischargeable power sources (batteries), and a converter (power conversion device) is required to charge and discharge the lithium-ion battery. A lithium-ion battery has a characteristic that its open-circuit voltage changes significantly depending on the charging state. Therefore, converters are required to be able to handle a wide range of input / output voltage ratios and bidirectional power transmission, and to perform power conversion with high efficiency. A known bidirectional converter is the DAB (Dual Active Bridge) converter (for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Jun Higa, Shunsuke Takuma, Keisuke Kusaka, and Junichi Ito, "Development of a T-type Dual Active Bridge DC-DC Converter with Operation Mode Switching Method for a Wide Voltage Drive Range," IEEJ Transactions on Power Electronics, Vol. 139, No. 4, 2019, pp. 388-400 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional DAB converter described in Non-Patent Document 1, a bidirectional FET (S in Fig. 1 of Non-Patent Document 1) is used to switch between full-bridge operation and half-bridge operation. ucp , S ucn ) and a voltage dividing capacitor (C p , C nHowever, the configuration of the DAB converter described in Non-Patent Document 1 may be disadvantageous in terms of the circuitry and the cost.

[0005] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a power conversion device capable of switching between full-bridge operation and half-bridge operation with a simple configuration. [Means for solving the problem]

[0006] In order to achieve the above object, a power conversion device according to one aspect of the present invention is a power conversion device that performs power conversion to supply power bidirectionally between a first device and a second device, No. 1 A transformer; a transformer unit including a second transformer having a different turns ratio from the first transformer; The transformer unit a primary circuit provided on the primary side of the transformer and connected to the first device; unit and a secondary circuit provided on the secondary side of the first contact and connected to the second device, the primary circuit including two contacts connected in series via a first contact. of The first leg contains the switching element, and the second leg is connected in series with the two of a second leg including a switch element; a third leg including two switch elements connected in series via a third contact; having the secondary side circuit has a fourth leg including two switch elements connected in series via a fourth contact, a fifth leg including two switch elements connected in series via a fifth contact, and a sixth leg including two switch elements connected in series via a sixth contact, The above No. 1 One end of the primary coil of a transformer but Connected to the first contact 、 Other end is the first connected to the second contact via a capacitor; one end of a primary coil of the second transformer is connected to the third contact and the other end is connected to the second contact via the first capacitor, one end of a secondary coil of the first transformer is connected to the fourth contact and the other end is connected to the fifth contact via the second capacitor, one end of a secondary coil of the second transformer is connected to the sixth contact and the other end is connected to the fifth contact via the second capacitor, In the primary side circuit, the first leg 、 The second leg and each of the third legs In Two Full-bridge operation is performed by alternately switching the switch elements on and off at specified intervals. Be , the first leg 、 The second leg or the third leg In Two Half-bridge operation is achieved by keeping one of the switch elements always on and the other always off. Will be , characterized in that Effect of the Invention

[0007] According to the present invention, for example, it is possible to provide a power conversion device capable of switching between full-bridge operation and half-bridge operation with a simple configuration. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a configuration example of a power conversion device; [Diagram 2] FIG. 1 is a schematic diagram showing the configuration of a primary side circuit in a conventional converter and a converter of the present invention. [Diagram 3] FIG. 1 is a diagram showing an example of half-bridge operation in a converter according to the present invention; [Figure 4] A diagram showing the operation mode (basic mode) of the power conversion device [Diagram 5] A diagram showing the operation modes of a power conversion device. [Figure 6] Conceptual diagram showing the relationship between input / output voltage ratio and output power [Figure 7] FIG. 1 is a diagram showing an example of operation of a power conversion device (first basic mode); [Figure 8] FIG. 1 shows an example of operation of a power conversion device (second basic mode). [Figure 9] FIG. 1 shows an example of operation of a power conversion device (third basic mode). [Figure 10] FIG. 1 shows an example of operation of a power conversion device (fourth basic mode). [Figure 11] FIG. 1 is a diagram showing an example of operation of a representative power conversion device in a first fundamental mode. [Figure 12] FIG. 1 shows the operating waveforms of each switch element in the primary circuit in the first fundamental mode, and the waveform of the output voltage from the primary circuit. [Figure 13] FIG. 13 is a diagram showing an example of operation of a representative power conversion device in a third fundamental mode. [Figure 14] FIG. 13 is a diagram showing an example of operation of a representative power conversion device in a fourth fundamental mode. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiment, and includes changes and modifications of the configuration within the scope of the present invention. Furthermore, not all of the combinations of features described in the present embodiment are necessarily essential to the present invention. Note that the same components are given the same reference numbers and their description will be omitted.

[0010] FIG. 1 is a diagram showing a configuration example of a power conversion device 10 according to an embodiment of the present invention. The power conversion device 10 of this embodiment is a bidirectional insulating converter that performs power conversion to supply power bidirectionally between a first device D1 and a second device D2. That is, the power conversion device 10 is configured to be able to supply power from the first device D1 to the second device D2 and to supply power from the second device D2 to the first device D1. The first device D1 may be a chargeable and dischargeable battery such as a lithium ion battery. The second device D2 may be a load (such as a device such as a motor) to which power is supplied from the battery as the first device D1, or a power source (such as a charger) that supplies power to the battery as the first device D1. In this embodiment, an example will be described in which a battery is used as the first device D1 and a load is used as the second device D2.

[0011] The power conversion device 10 of the present embodiment may be mounted on an electric vehicle, a hybrid vehicle, or the like. The vehicle on which the power conversion device 10 is mounted may be a four-wheeled vehicle, or a vehicle other than a four-wheeled vehicle, such as a saddle-type vehicle (motorcycle, three-wheeled vehicle). Furthermore, the power conversion device 10 of the present embodiment may be mounted on a moving body other than a vehicle, such as a ship or an aircraft.

[0012] [Example of power conversion device configuration] A configuration example of the power conversion device 10 of the present embodiment will be described with reference to FIG. 1. As shown in FIG. 1, the power conversion device 10 of the present embodiment may include a transformer unit 11, a primary side circuit 12A, a secondary side circuit 12B, and a control unit 13. The control unit 13 is configured by a computer including a processor such as a CPU, a storage device such as a semiconductor memory, an interface with an external device, and the like, and may control power conversion in the transformer unit 11 by controlling a plurality of switch elements included in the primary side circuit 12A and a plurality of switch elements included in the secondary side circuit 12B. Here, in the present embodiment, the control unit 13 is provided as a component of the power conversion device 10, but is not limited thereto. For example, an external control device such as an ECU (Electronic Control Unit) provided in a vehicle may function as the control unit 13.

[0013] The transformer unit 11 includes a first transformer Tr1 and a second transformer Tr2. The first transformer Tr1 has a number of turns n p1 A primary coil having a number of turns n s1 The second transformer Tr2 is composed of a secondary coil having a number of turns n p2 A primary coil having a number of turns n s2 The second transformer Tr2 is composed of a secondary coil having a turn ratio (n s2 / n p2 ) is the turns ratio of the first transformer Tr1 (n s1 / n p1 In this embodiment, the winding ratio of the second transformer Tr2 is larger than the winding ratio of the first transformer Tr1. In the transformer unit 11 of this embodiment, the inductor L 3 (coil) is connected in series with the inductor L 4 (coils) are connected in series.

[0014] Next, the configuration of the primary circuit 12A will be described. The primary circuit 12A is provided on the primary side of the transformer unit 11, and is connected to the first device D1 (battery). The primary circuit 12A is configured with a plurality of switch elements, and the voltage of the primary coil of the transformer unit 11 (first transformer Tr1, second transformer Tr2) can be controlled by the control unit 13 controlling the plurality of switch elements. Specifically, the primary circuit 12A is configured as a current fed converter (CFC) having a boost function expanded to three phases, and has a first leg 21, a second leg 22, and a third leg 23 connected in parallel to each other.

[0015] The first leg 21 is the first contact b 1 Two first switch elements (switch elements S p1 , S p2 ), one end of which is the first line a 1 and the other end is connected to the second line a 2 The one end of the first leg 21 is arranged to be connected to the switch element S p1 The first contact b of the two terminals 1 The other end of the first leg 21 is a terminal opposite to the terminal connected to the switch element S p2 The first contact b of the two terminals 1 This is the terminal opposite to the terminal connected to

[0016] The second leg 22 has a second contact b 2 Two second switch elements (switch elements S p3 , S p4 ), one end of which is the first line a 1 and the other end is connected to the second line a 2 The second leg 22 is arranged in parallel with the first leg 21 so as to be connected to the switch element S p3 The second contact b of the two terminals 2 The other end of the second leg 22 is a terminal opposite to the terminal connected to the switch element S p4 The second contact b of the two terminals 2This is the terminal opposite to the terminal connected to

[0017] The third leg 23 is the third contact b 3 Two third switch elements (switch elements S p5 , S p6 ), one end of which is the first line a 1 and the other end is connected to the second line a 2 The third leg 23 is arranged in parallel with the first leg 21 and the second leg 22 so as to be connected to the first leg 21 and the second leg 22. p5 The third contact b of the two terminals 3 The other end of the third leg 23 is a terminal opposite to the terminal connected to the switch element S p6 The third contact b of the two terminals 3 This is the terminal opposite to the terminal connected to

[0018] Each switch element S p1 ~S p6 The first line a may be a transistor (power element) that performs a switching operation, such as an IGBT or a MOSFET. 1 and second line a 2 Each of the first line a may be understood as a current path. 1 is the capacitor C 1 (capacitor) through the second line a 2 is connected to

[0019] The first device D1 (battery) has one end (negative terminal) connected to the second line a 2 and the other end (positive terminal) is connected to the first contact b 1 and third contact b 3 In this embodiment, as shown in FIG. 1, the other end of the first device D1 is connected to an inductor L 1 (coil) through the first contact b 1 and the inductor L 2 (coil) through the third contact b 3In the primary circuit 12A of the present embodiment, a capacitor C 2 (capacitor) is provided. In this way, the inductor L 1 ~L 2 and capacitor C 1 ~C 2 By providing the inductor L, a CL filter can be formed, and it is possible to prevent the inflow of harmonic current into the first device D1. 1 and inductor L 2 By configuring a current-fed converter by providing the above, it becomes possible to apply a voltage higher than the voltage across the first device D1 to each transformer.

[0020] Here, the connection between the transformer unit 11 and the primary circuit 12A will be described. The primary coil of the first transformer Tr1 of the transformer unit 11 has one end connected to a first contact b 1 and the other end is connected to the second contact b 2 The primary coil of the second transformer Tr2 of the transformer unit 11 is arranged so as to be connected to the second contact b 2 and the other end is connected to the third contact b 3 The other end of the primary coil of the first transformer Tr1 and the other end of the primary coil of the second transformer Tr2 are connected to a capacitor C 3 (capacitor) through the second contact b 2 In this way, the capacitor C 3 By providing the capacitor C, it becomes possible to selectively switch between full-bridge operation and half-bridge operation in the primary circuit 12A. 3 By providing the switch element S p1 ~S p6 This also has the effect of cutting the DC component of the voltage applied to the transformer caused by control deviations, etc., and reducing DC bias magnetism that causes DC current components in the coil currents of the first transformer Tr1 and the second transformer Tr2.

[0021] In the primary circuit 12A configured as described above, a full-bridge operation can be performed by alternately switching on / off two switch elements in each of the legs 21 to 23 at predetermined intervals. As an example, the two first switch elements (switch elements S p1 , S p2 ) are alternately switched on and off at predetermined time intervals, and two second switch elements (switch elements S p3 , S p4 ) are alternately switched on / off at the predetermined time intervals, and the two third switch elements (switch elements S p5 , S p6 A full-bridge operation can be performed by alternately switching on / off the two switch elements in the first leg 21, the second leg 22, or the third leg 23 at predetermined intervals. Also, in the primary side circuit 12A, a half-bridge operation can be performed by keeping one of the two switch elements in the first leg 21, the second leg 22, or the third leg 23 always on and the other always off. As an example, the two first switch elements (switch elements S p1 , S p2 ) in the second leg 22 is always on and the other is always off, or p3 , S p4 ) is always on and the other is always off, or two third switch elements (switch elements S p5 , S p6 ) can be always on and the other always off to achieve half-bridge operation.

[0022] Next, the configuration of the secondary circuit 12B will be described. The secondary circuit 12B is provided on the secondary side of the transformer unit 11, and is connected to the second device D2 (load, charger). The secondary circuit 12B is configured with a plurality of switch elements, and the voltage of the secondary coil of the transformer unit 11 (first transformer Tr1, second transformer Tr2) can be controlled by the control unit 13 controlling the plurality of switch elements. Specifically, the primary circuit 12A has a fourth leg 24, a fifth leg 25, and a sixth leg 26 connected in parallel to each other.

[0023] The fourth leg 24 is the fourth contact b 4 Two fourth switch elements (switch elements S s1 , S s2 ) and one end is the third line a 3 and the other end is connected to the 4th line a 4 The one end of the fourth leg 24 is arranged to be connected to the switch element S s1 The fourth contact b of the two terminals 4 The other end of the fourth leg 24 is a terminal opposite to the terminal connected to the switch element S s2 The fourth contact b of the two terminals 4 This is the terminal opposite to the terminal connected to

[0024] The fifth leg 25 is the fifth contact point b 5 Two fifth switch elements (switch elements S s3 , S s4 ) and one end is the third line a 3 and the other end is connected to the 4th line a 4 The fifth leg 25 is arranged in parallel with the fourth leg 24 so as to be connected to the switch element S s3 The fifth contact b of the two terminals 5 The other end of the fifth leg 25 is a terminal opposite to the terminal connected to the switch element S s4 The fifth contact b of the two terminals 5 This is the terminal opposite to the terminal connected to

[0025] The sixth leg 26 is the sixth contact point b 6 Two sixth switch elements (switch elements S s5 , S s6 ) and one end is the third line a 3 and the other end is connected to the 4th line a 4 The sixth leg 26 is arranged in parallel with the fourth leg 24 and the fifth leg 25 so as to be connected to the s5 The sixth contact b of the two terminals 6 The other end of the sixth leg 26 is a terminal opposite to the terminal connected to the switch element S s6 The sixth contact b of the two terminals 6 This is the terminal opposite to the terminal connected to

[0026] Each switch element S s1 ~S s6 The third line a may be a transistor (power element) that performs a switching operation, such as an IGBT or a MOSFET. 3 and 4th line a 4 Each of the lines may be understood as a current path, and the third line a 3 is the capacitor C 4 (capacitor) through the 4th line a 4 The second device D2 (load, charger) is connected to the third line a 3 and the other end is connected to the 4th line a 4 The device is arranged to be connected to the

[0027] Here, the connection between the transformer unit 11 and the secondary circuit 12B will be described. The secondary coil of the first transformer Tr1 of the transformer unit 11 has one end connected to the fourth contact b 4 and the other end is connected to the fifth contact b 5 The secondary coil of the second transformer Tr2 of the transformer unit 11 is arranged so as to be connected to the fifth contact b 5 and the other end is connected to the sixth contact b 6 The other end of the secondary coil of the first transformer Tr1 and the other end of the secondary coil of the second transformer Tr2 are connected to a capacitor C5 (capacitor) through the fifth contact B 5 In this way, the capacitor C 5 By providing the capacitor C, it becomes possible to selectively switch between full-bridge operation and half-bridge operation in the secondary circuit 12B. 5 By providing the switch element S s1 ~S s6 This also has the effect of cutting the DC component of the voltage applied to the transformer caused by control deviations, etc., and reducing DC bias magnetism that generates a DC current component in the coil current of the first transformer Tr1 and the second transformer Tr2.

[0028] In the secondary circuit 12B configured as described above, a full-bridge operation can be performed by alternately switching on / off two switch elements in each of the legs 24 to 26 at predetermined intervals. As an example, the two fourth switch elements (switch elements S s1 , S s2 ) are alternately switched on and off at predetermined time intervals, and two fifth switch elements (switch elements S s3 , S s4 ) are alternately switched on / off at the predetermined time intervals, and two sixth switch elements (switch elements S s5 , S s6 A full-bridge operation can be performed by alternately switching on / off the second switch elements S1 and S2 in the fourth leg 24, the fifth leg 25, or the sixth leg 26 at predetermined intervals. Also, in the secondary circuit 12B, one of the two switch elements in the fourth leg 24, the fifth leg 25, or the sixth leg 26 is always on and the other is always off, thereby performing a half-bridge operation. As an example, the two fourth switch elements (switch elements S1 and S2 in the fourth leg 24) in the fourth leg 24 can be alternately switched on / off at predetermined intervals. s1 , S s2 ) is always on and the other is always off, or two fifth switch elements (switch elements S s3 , S s4 ) is always on and the other is always off, or two sixth switch elements (switch elements S s5 , Ss6 ) can be always on and the other always off to achieve half-bridge operation.

[0029] Next, the differences in configuration and operation of the primary side circuit between the conventional converter and the converter of the present invention will be described. FIG. 2(a) is a schematic diagram showing the configuration of the primary side circuit in the conventional converter described in the above Non-Patent Document 1, and FIG. 2(b) is a schematic diagram showing the configuration of the primary side circuit of the converter of the present invention (the power conversion device 10 of this embodiment). The switch element S in FIG. 2(b) a ~S b is the switch element S in Fig. p3 ~S p4 2(b) may be understood as corresponding to the primary coil of the first transformer Tr1 or the primary coil of the second transformer Tr2. When the element A in FIG. 2(b) corresponds to the primary coil of the first transformer Tr1, the switch element S in FIG. c ~S d is the switch element S in Fig. p1 ~S p2 On the other hand, when the element A in FIG. 2(b) corresponds to the secondary coil of the second transformer Tr2, the switch element S in FIG. c ~S d is the switch element S in Fig. p5 ~S p6 In addition, the capacitor C in Fig. 2(b) corresponds to 3 is the capacitor C in Figure 1. 3 Corresponds to.

[0030] In the primary circuit of a conventional converter, a bidirectional FET (switch element S) is used to enable half-bridge operation, as shown in Figure 2(a). ucp , S ucn ) and a voltage divider capacitor (C p , C n In contrast, in the converter of the present invention, instead of the bidirectional FET and the voltage divider capacitor, a single capacitor C 3is simply connected in series with element A (the primary coil of the transformer). This can be advantageous in terms of circuit simplification and cost. 3 The two switch elements S in the leg to which a , S b By alternately switching on and off at a predetermined time, full-bridge operation can be performed, and the two switch elements S a , S b A half-bridge operation can be performed by keeping one of the capacitors always on and the other always off. 3 The leg to which the two switch elements S a , S b " is the switch element S in Figure 1. p3 , S p4 correspond to the following:

[0031] Fig. 3 shows an example of half-bridge operation in the converter of the present invention shown in Fig. 2(b). Fig. 3(a) shows a schematic diagram showing the half-bridge operation of the primary side circuit, and Fig. 3(b) shows the switching elements S a ~S d and the applied voltage V to element A. o In the example of FIG. 3, the switching element S a is always off, and the switch element S b In the state where the switch element S c , S d This alternates between on and off at regular intervals. This reduces the applied voltage V o Since the amplitude of the voltage E applied to each leg is half that of the voltage E applied to each leg, half-bridge operation can be performed. a is always off, and the switch element S b is always on, but the opposite (i.e., switch element S a is always on, and the switch element S b half-bridge operation can be performed even when the power supply is always off.

[0032] [Power conversion device operating mode] With the above configuration, the power conversion device 10 of this embodiment can execute four types of operation modes (hereinafter sometimes referred to as basic modes) in which the first transformer Tr1 and the second transformer Tr2 in the transformer unit 11 are selectively operated, as shown in Fig. 4. That is, the power conversion device 10 of this embodiment can selectively execute the first to fourth basic modes.

[0033] The first basic mode (first mode) is a mode (Tr1 mode) in which power conversion is performed by operating only the first transformer Tr1 without operating the second transformer Tr2. In this first basic mode, the number of turns (n p1 ) and the number of turns of the secondary coil of the first transformer Tr1 (n s1 ) and the ratio (n s1 / n p1 ) is obtained as a representative input / output voltage ratio. The second basic mode (second mode) is a mode (Tr2 mode) in which power conversion is performed by operating only the second transformer Tr2 without operating the first transformer Tr1. In this second basic mode, the number of turns (n p2 ) and the number of turns of the secondary coil of the second transformer Tr2 (n s2 ) and the ratio (n s2 / n p2 ) is obtained as a representative input / output voltage ratio. The input / output voltage ratio is defined as the ratio of the input voltage from one of the first device D1 and the second device D2 to the output voltage to the other device. For example, when power is supplied from the first device D1 to the second device D2, the input / output voltage ratio can be defined as the ratio of the output voltage to the second device D2 to the input voltage from the first device D1.

[0034] The third basic mode (third mode) is a mode (Tr1 / / Tr2 mode) in which power conversion is performed by operating the first transformer Tr1 and the second transformer Tr2 in parallel and independently. A representative input / output voltage ratio in this third basic mode is the ratio of the number of turns of the primary coil of the first transformer Tr1 to the number of turns of the secondary coil of the first transformer Tr1 (n s1 / n p1 ), and the ratio of the number of turns of the primary coil of the second transformer Tr2 to the number of turns of the secondary coil of the second transformer Tr2 (n s2 / n p2 ). The fourth basic mode (fourth mode) is a mode (Tr1&Tr2 mode) in which power conversion is performed by operating the first transformer Tr1 and the second transformer Tr2 as a single unit in series. A representative input / output voltage ratio in this fourth basic mode is the ratio of the sum of the number of turns of the secondary coil of the first transformer Tr1 and the number of turns of the secondary coil of the second transformer Tr2 to the sum of the number of turns of the primary coil of the first transformer Tr1 and the number of turns of the primary coil of the second transformer Tr2 ((n s1 +n s2 ) / (n p1 +n p2 )).

[0035] Moreover, with the power conversion device 10 of this embodiment, by adopting the above-mentioned configuration, four types of operation modes (hereinafter sometimes referred to as sub-modes) in which each of the primary side circuit 12A and the secondary side circuit 12B is selectively switched between full-bridge operation and half-bridge operation can be executed as operation modes. That is, the power conversion device 10 of this embodiment can selectively execute the first to fourth sub-modes.

[0036] The first sub-mode is a mode in which both the primary side circuit 12A and the secondary side circuit 12B are operated in full-bridge operation. The second sub-mode is a mode in which only the primary side circuit 12A is operated in half-bridge operation, and the secondary side circuit 12B is operated in full-bridge operation. The third sub-mode is a mode in which only the secondary side circuit 12B is operated in half-bridge operation, and the primary side circuit 12A is operated in full-bridge operation. The fourth sub-mode is a mode in which both the primary side circuit 12A and the secondary side circuit 12B are operated in half-bridge operation.

[0037] In the power conversion device 10 of this embodiment, the first to fourth sub-modes can be selectively executed for each of the first to third basic modes, and the second to fourth sub-modes can be selectively executed for the fourth basic mode, as shown in Fig. 5. Therefore, in the power conversion device 10 of this embodiment, with the above configuration, the transformer unit 11 can be operated in each of 15 types of operation modes, and power conversion can be performed with high efficiency over a wider range of input / output voltage ratios.

[0038] FIG. 6 is a conceptual diagram showing the relationship between the input / output voltage ratio and the output power (which may be understood as the output voltage from the secondary side circuit 12B). The region R in FIG. 6 indicates the region in which the power conversion device 10 can operate (i.e., the region in which soft switching is possible). As shown in FIG. 6, the first basic mode can cover a portion in which the input / output voltage ratio is relatively low. On the other hand, the second basic mode can cover a portion in which the input / output voltage ratio is relatively high. Also, the third basic mode can cover a portion in which the output power is relatively high among the portions in which the input / output voltage ratio is higher than that of the first basic mode and lower than that of the second basic mode. In this third basic mode, the current is divided between the first transformer Tr and the second transformer Tr, and the conduction loss can be reduced more than when one of the first transformer Tr1 and the second transformer Tr2 is used. And, the fourth basic mode can cover a portion in which the input / output voltage ratio is higher than that of the first basic mode and lower than that of the second basic mode among the portions in which the output power is relatively low. In this way, the power conversion device 10 of the present embodiment has 15 types of operation modes, so that the control unit 13 can finely switch the operation mode according to the target input / output voltage ratio (i.e., the required input / output voltage ratio). This makes it possible to perform highly efficient power conversion over a wider range of input / output voltage ratios.

[0039] [Example of power conversion device operation] Next, an operation example of the power conversion device 10 of the present embodiment will be described. p1 ~S p6 and each switch element S of the secondary circuit 12B s1 ~S s6Power conversion can be performed by switching ON (conducting) / OFF (non-conducting) at predetermined intervals (times). Figs. 7 to 10 show examples of operation of the power conversion device 10. Fig. 7 shows an example of operation in the first basic mode (Tr1 mode), Fig. 8 shows an example of operation in the second basic mode (Tr2 mode), Fig. 9 shows an example of operation in the third basic mode (Tr1 / / Tr2 mode), and Fig. 10 shows an example of operation in the fourth basic mode (Tr1&Tr2 mode). In each of Figs. 7 to 10, (a) shows an example of operation in the first sub-mode, (b) shows an example of operation in the second sub-mode, (c) shows an example of operation in the third sub-mode, and (d) shows an example of operation in the fourth sub-mode.

[0040] Each table in FIG. 7 to FIG. 10 shows the configuration of each switch element S of the primary side circuit 12A. p1 ~S p6 and each switch element S of the secondary circuit 12B s1 ~S s6 The on (conducting) / off (non-conducting) states of each switch element S in each table are switched in sequence from Period 1 to Period 4. p1 ~S p6 , S s1 ~S s6 In the above, "1" indicates an on state (energized state), and "0" indicates an off state (non-energized state). In each table, it may be understood that when period 4 ends, period 1 starts again. Note that each table in Figs. 7 to 10 is merely an example of the operation of each switch element for executing each operation mode (basic mode, sub-mode), and each operation mode (basic mode, sub-mode) can be realized even when on / off control of each switch operation different from the operation example shown in Figs. 7 to 10 is performed.

[0041] Here, a typical example of the operation of the power conversion device 10 in each basic mode will be described with reference to a circuit diagram. Figs. 11 to 14 show typical examples of the operation of the power conversion device 10 in each basic mode. Note that the example of the operation of the power conversion device 10 described below is a simplification of the example of the operation described with reference to Figs. 7 to 10 to make it easier to understand, and does not necessarily match the example of the operation shown in Figs. 7 to 10. For example, when each switch element S in the primary side circuit 12A is p1 ~S p6 and the switching timing of each switch element S in the secondary circuit 12B. s1 ~S s6 The switching timings are not simultaneous, but can be performed according to the operation examples shown in FIGS.

[0042] FIG. 11 shows an operation example (i.e., an example corresponding to FIG. 7(a)) of the power conversion device 10 in the first sub-mode of the first basic mode. In FIG. 11, only the primary side circuit 12A is shown, and the transformer unit 11 and the secondary side circuit 12B are omitted. In FIG. 11, each switch element S in the primary side circuit 12A is p1 ~S p6 The figure is a simplified version of the "E MPP " indicates the voltage of the first device D1 (battery), and "E pdc " is the voltage applied to each leg 21 to 23 of the primary circuit 12A (i.e., line a 1 and line a 2 The operation of the power conversion device 10 in the first sub-mode of the second basic mode can be considered to be similar to the operation of the power conversion device 10 in the first sub-mode of the first basic mode.

[0043] FIG. 11 shows an example of the first sub-mode of the first basic mode, which can be realized by switching between an upper state 1A and a lower state 1B. In the upper state 1A, the switch element S p1 , S p4 , S p6 is turned on (conducting), and the switch element S p2 , S p3 , Sp5 On the other hand, in the lower state 1B, the switch element S p2 , S p3 , S p5 is turned on (conducting), and the switch element S p1 , S p4 , S p6 Here, the switch element S of the primary circuit 12A is turned off (non-conducting). p1 , S p3 , S p5 On / off duty ratio D p D p =t p On the other hand, the switch element S p2 , S p4 , S p6 In the case of line a 1 and line a 2 To prevent a short circuit, switch element S p1 , S p3 , S p5 Since it is on during the period when it is off, the on / off duty ratio is 1-D p In the above formula, "t p " is the switch element S p1 , S p3 , S p5 The on-time of each switch element is “T”, and “T” is the period of switching operation of each switch element. p = 0.5, the first sub-mode of the first fundamental mode can be realized with other duty ratios.

[0044] 12 is a timing chart showing the operation waveforms of the switching elements of the primary circuit 12A in the first basic mode and the waveform of the output voltage from the primary circuit 12A. p The output voltage trend changes depending on the D p <0.5" is shown in Fig. 12(a). p Figure 12(b) shows the case of "D = 0.5". p The cases of "D > 0.5" are shown in Fig. 12(c). p<0.5", the effective value of the voltage applied to the primary coil of the first transformer Tr1 |V pab | (see FIG. 1) is expressed by the formula shown in FIG. 12(a). p When V = 0.5, the effective value of the voltage applied to the primary coil of the first transformer Tr1 is |V pab | is expressed by the formula shown in FIG. 12(b). p > 0.5", the effective value of the voltage applied to the primary coil of the first transformer Tr1 |V pab | is expressed by the formula shown in FIG. 12(c). Here, "E pdc As described above, " indicates the voltage applied to each of the legs 21 to 23 in the primary circuit 12A.

[0045] FIG. 13(a) shows an operation example of the power conversion device 10 in the first sub-mode of the third basic mode (i.e., an example corresponding to FIG. 9(a)), and FIG. 13(b) shows an operation example of the power conversion device 10 in the second sub-mode of the third basic mode (i.e., an example corresponding to FIG. 9(b)). In FIGS. 13(a)-(b), only the primary side circuit 12A is shown, and the transformer unit 11 and the secondary side circuit 12B are omitted. In addition, in FIGS. 13(a)-(b), each switch element S in the primary side circuit 12A is shown in the same manner as in FIG. 11. p1 ~S p6 The figure is simplified and illustrated as "E MPP " is the voltage of the first device D1 (battery), "E pdc " respectively indicate the voltages applied to the legs 21 to 23 of the primary circuit 12A.

[0046] FIG. 13(a) shows an example of the first sub-mode of the third basic mode, which can be realized by switching between an upper state 2A and a lower state 2B. In the upper state 2A, the switching element S p2 , S p3 , S p6 is turned on (conducting), and the switch element S p1 , S p4 , S p5 On the other hand, in the lower state 2B, the switch element Sp1 , S p4 , S p5 is turned on (conducting), and the switch element S p2 , S p3 , S p6 In the operation of the power conversion device 10 in the first sub-mode of the third basic mode, the switch element S p3 , S p4 By switching the capacitor C 3 (See Figure 1) can be considered as a conductor.

[0047] FIG. 13(b) shows an example of the second sub-mode of the third basic mode, which can be realized by switching between an upper state 3A and a lower state 3B. In the upper state 3A, the switching element S p1 , S p4 , S p5 is turned on (conducting), and the switch element S p2 , S p3 , S p6 On the other hand, in the lower state 3B, the switch element S p2 , S p4 , S p6 is turned on (conducting), and the switch element S p1 , S p3 , S p5 In the operation of the power conversion device 10 in the second sub-mode of the third basic mode, the switch element S p3 Turn off (non-conducting) S p4 By keeping the on (conducting) state, the capacitor C 3 The voltage generated at (E pdc / 2) to perform half-bridge operation.

[0048] FIG. 14 shows an operation example of the power conversion device 10 in the second sub-mode of the fourth basic mode (i.e., an example corresponding to FIG. 10(b)). FIG. 14(a) shows the primary side circuit 12A, and FIG. 14(b) shows the secondary side circuit 12B. Also, in FIG. 14, similar to FIGS. 11 and 13, each switch element S in the primary side circuit 12A is p1 ~Sp6 , and each switch element S in the secondary circuit 12B s1 ~S s6 The figure is simplified and illustrated as "E MPP " is the voltage of the first device D1 (battery), "E pdc " indicates the voltages applied to the legs 21 to 23 of the primary circuit 12A. inv " indicates the output voltage from the transformer unit 11 (which may be understood as the output voltage to the second device D2).

[0049] 14 shows an example of the second sub-mode of the fourth basic mode, which can be realized by switching between an upper state and a lower state. In the upper state 4A of the primary circuit 12A shown in FIG. 14(a), the switching element S p1 , S p4 , S p6 is turned on (conducting), and the switch element S p2 , S p3 , S p5 On the other hand, in the lower state 4B, the switch element S p2 , S p4 , S p5 is turned on (conducting), and the switch element S p1 , S p3 , S p6 In the upper state 5A of the secondary circuit 12A shown in FIG. 14(b), the switch element S s1 , S s6 is turned on (conducting), and the switch element S s2 , S s3 , S s4 , S p5 On the other hand, in the lower state 5B, the switch element S s2 , S s5 is turned on (conducting), and the switch element S s1 , S s3 , S s4 , S p6 In addition, each switch element S in the primary circuit 12A is turned off (non-conductive). p1 ~S p6 and the switching timing of each switch element S in the secondary circuit 12B. s1~S s6 The switching timing is not simultaneous with that of the above, but may be performed according to the operation example shown in FIG.

[0050] As described above, the power conversion device 10 of the present embodiment is configured to be selectively operable in a first basic mode in which only the first transformer Tr1 is operated, a second basic mode in which only the second transformer Tr is operated, a third basic mode in which the first transformer Tr1 and the second transformer Tr2 are operated in parallel, and a fourth basic mode in which the first transformer Tr1 and the second transformer Tr2 are operated in series. This allows operation in each of a plurality of operation modes with different input / output voltage ratios, thereby enabling highly efficient power conversion over a wider range of input / output voltage ratios.

[0051] The power conversion device 10 of the present embodiment is configured to be able to selectively execute a first sub-mode in which both the primary side circuit 12A and the secondary side circuit 12B are operated in full-bridge operation, a second sub-mode in which only the primary side circuit 12A is operated in half-bridge operation, a third sub-mode in which only the secondary side circuit 12B is operated in half-bridge operation, and a fourth sub-mode in which both the primary side circuit 12A and the secondary side circuit 12B are operated in half-bridge operation. This allows operation in more operation modes, so that the operation modes can be switched finely according to the input / output voltage ratio, making it possible to perform highly efficient power conversion over a wider range of input / output voltage ratios.

[0052] Furthermore, in the power conversion device 10 of the present embodiment, in the primary circuit 12A, the primary coil of the first transformer Tr1 and the primary coil of the second transformer Tr2 are connected to a capacitor C 3 via the second contact b 2 With such a simple configuration, the primary circuit 12A can selectively switch between full-bridge operation and half-bridge operation. Similarly, in the secondary circuit 12B, the secondary coil of the first transformer Tr1 and the secondary coil of the second transformer Tr2 are connected to the capacitor C 5 Through the fifth contact B 5With such a simple configuration, it becomes possible to selectively switch between a full-bridge operation and a half-bridge operation in the secondary circuit 12B.

[0053] <Summary of the embodiment> 1. The power conversion device of the above embodiment is A power conversion device (e.g., 10) that performs power conversion to supply power bidirectionally between a first device (e.g., D1) and a second device (e.g., D2), A transformer (e.g. Tr1), A primary circuit (e.g., 12A) provided on the primary side of the transformer and connected to the first device; A secondary circuit (e.g., 12B) provided on the secondary side of the transformer and connected to the second device; Equipped with The primary circuit includes a first contact (e.g., b 1 Two first switch elements (e.g., S p1 , S p2 ) and the first leg (e.g. 21) including the second contact (e.g. b 2 ) connected in series with two second switch elements (e.g., S p3 , S p4 and a second leg (e.g., 22) including One end of the primary coil of the transformer is connected to the first contact, and the other end of the primary coil of the transformer is connected to a capacitor (e.g., C 3 ) connected to the second contact, In the primary side circuit, a full-bridge operation can be performed by alternately switching on / off the two first switch elements in the first leg and the two second switch elements in the second leg at predetermined time intervals, and a half-bridge operation can be performed by keeping one of the two first switch elements in the first leg always on and the other always off, or keeping one of the two second switch elements in the second leg always on and the other always off. According to this configuration, it is possible to selectively switch between full-bridge operation and half-bridge operation in the primary side circuit, and this is advantageous in terms of circuit simplification and cost.

[0054] 2. In the above embodiment, Each of the first leg and the second leg has one end connected to a first line (e.g., 1 ) and the other end is connected to the second line (e.g. a 2 ) and The first line is connected to a second capacitor (e.g., C 1 ) connected to the second line, The first device is arranged such that one end is connected to the second line and the other end is connected to the first contact. According to this configuration, it is possible to selectively switch between full-bridge operation and half-bridge operation in the primary side circuit.

[0055] 3. In the above embodiment, The power conversion device further includes a second transformer (e.g., Tr2) having a different turn ratio from that of the transformer, The primary circuit has a third contact (e.g., b 3 Two third switch elements (e.g., S p5 , S p6 ) and a third leg (e.g., 23) including One end of the primary coil of the second transformer is connected to the third contact, and the other end of the primary coil of the second transformer is connected to the second contact via the capacitor. According to this configuration, a plurality of types of operation modes (first to fourth basic modes, first to fourth sub-modes) can be selectively executed, making it possible to perform highly efficient power conversion over a wider range of input / output voltage ratios.

[0056] 4. In the above embodiment, Each of the first leg, the second leg, and the third leg has one end connected to a first line (e.g., 1 ) and the other end is connected to the second line (e.g. a2 ) and The first line is connected to a second capacitor (e.g., C 1 ) connected to the second line, The first device is arranged such that one end is connected to the second line and the other end is connected to the first contact and the third contact. According to this configuration, it is possible to selectively switch between full-bridge operation and half-bridge operation in the primary side circuit, thereby efficiently performing power conversion between the first device and the second device.

[0057] 5. In the above embodiment, The secondary circuit has a fourth contact (e.g., b 4 Two fourth switch elements (e.g., S s1 , S s2 ) and the fourth leg (e.g. 24) including the fifth contact (e.g. b 5 Two fifth switch elements (e.g., S s3 , S s4 ) and a fifth leg (e.g., 25) including One end of the secondary coil of the transformer is connected to the fourth contact, and the other end of the secondary coil of the transformer is connected to a third capacitor (e.g., C 5 ) connected to the fifth contact, In the secondary side circuit, a full-bridge operation can be performed by alternately switching on / off the two fourth switch elements in the fourth leg and the two fifth switch elements in the fifth leg at predetermined time intervals, and a half-bridge operation can be performed by keeping one of the two fourth switch elements in the fourth leg always on and the other always off, or keeping one of the two fifth switch elements in the fifth leg always on and the other always off. According to this configuration, it is possible to selectively switch between full-bridge operation and half-bridge operation in the secondary circuit, and this is advantageous in terms of circuit simplification and cost.

[0058] 6. In the above embodiment, Each of the fourth leg and the fifth leg has one end connected to a third line (e.g., 3 ), and the other end is connected to the fourth line (e.g. a 4 ) and The second device is arranged such that one end is connected to the third line and the other end is connected to the fourth line. According to this configuration, it is possible to selectively switch between full-bridge operation and half-bridge operation in the secondary circuit, thereby efficiently performing power conversion between the first device and the second device.

[0059] 7. In the above embodiment, The power conversion device further includes a second transformer (e.g., Tr2) having a different turn ratio from that of the transformer, The secondary circuit has a sixth contact (e.g., b 6 Two sixth switch elements (e.g., S s5 , S s6 ) and a sixth leg (e.g., 26) including One end of the secondary coil of the second transformer is connected to the sixth contact, and the other end of the secondary coil of the second transformer is connected to the fifth contact via the third capacitor. According to this configuration, a plurality of types of operation modes (first to fourth basic modes, first to fourth sub-modes) can be selectively executed, making it possible to perform highly efficient power conversion over a wider range of input / output voltage ratios.

[0060] 8. In the above embodiment, the first device is a battery; The second device is a load to which power is supplied from the first device, or a power source that supplies power to the first device. According to this configuration, it is possible to perform bidirectional power supply from the battery as the first device to the load as the second device, and from the power source as the second device to the battery as the first device.

[0061] The present invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0062] 10: power conversion device, 11: transformer unit, Tr1: first transformer, Tr2: second transformer, 12A: primary circuit, 12B: secondary circuit, 21 to 26: first to sixth legs, S p1 ~S p6 : Switching element of the primary circuit, S s1 ~S s6 : Switching element of the secondary circuit

Claims

1. A power conversion device that performs power conversion to supply power bidirectionally between a first device and a second device, a transformer unit including a first transformer and a second transformer having a turns ratio different from that of the first transformer; a primary side circuit provided on a primary side of the transformer unit and connected to the first device; a secondary circuit provided on a secondary side of the transformer unit and connected to the second device; Equipped with the primary side circuit has a first leg including two switch elements connected in series via a first contact, a second leg including two switch elements connected in series via a second contact, and a third leg including two switch elements connected in series via a third contact, the secondary side circuit has a fourth leg including two switch elements connected in series via a fourth contact, a fifth leg including two switch elements connected in series via a fifth contact, and a sixth leg including two switch elements connected in series via a sixth contact, one end of a primary coil of the first transformer is connected to the first contact, and the other end of the primary coil is connected to the second contact via a first capacitor; one end of a primary coil of the second transformer is connected to the third contact, and the other end of the primary coil is connected to the second contact via the first capacitor; one end of a secondary coil of the first transformer is connected to the fourth contact, and the other end of the secondary coil is connected to the fifth contact via a second capacitor; one end of a secondary coil of the second transformer is connected to the sixth contact, and the other end of the secondary coil is connected to the fifth contact via the second capacitor; In the primary side circuit, a full-bridge operation is performed by alternately switching on / off two switch elements in each of the first leg, the second leg, and the third leg at predetermined time intervals, and a half-bridge operation is performed by keeping one of the two switch elements in the first leg, the second leg, or the third leg always on and the other always off. A power conversion device comprising:

2. each of the first leg, the second leg, and the third leg is arranged such that one end is connected to a first line and the other end is connected to a second line; the first line is connected to the second line via a third capacitor; The first device is arranged such that one end is connected to the second line and the other end is connected to the first contact and the third contact.

2. The power conversion device according to claim 1 .

3. In the secondary side circuit, a full-bridge operation is performed by alternately switching on / off two switch elements in each of the fourth leg, the fifth leg and the sixth leg at predetermined time intervals, and a half-bridge operation is performed by keeping one of the two switch elements in the fourth leg, the fifth leg or the sixth leg always on and the other always off.

3. The power conversion device according to claim 1 or 2.

4. each of the fourth leg, the fifth leg, and the sixth leg is arranged such that one end is connected to the third line and the other end is connected to the fourth line; the second device is arranged such that one end is connected to the third line and the other end is connected to the fourth line; 4. The power conversion device according to claim 1, wherein the first and second electrodes are electrically connected to each other.

5. The third line is connected to the fourth line via a fourth capacitor.

5. The power conversion device according to claim 4.

6. the first device is a battery; The second device is a load to which power is supplied from the first device, or a power source that supplies power to the first device.

6. The power conversion device according to claim 1, wherein the first and second electrodes are electrically connected to each other.

7. A vehicle comprising the power conversion device according to any one of claims 1 to 6.

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