WO2014188249A2

WO2014188249A2 - Power conversion apparatus and voltage conversion method

Info

Publication number: WO2014188249A2
Application number: PCT/IB2014/000765
Authority: WO
Inventors: Takahiro Hirano; Takashi Fukai
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 2013-05-21
Filing date: 2014-05-20
Publication date: 2014-11-27
Also published as: JP2014230373A; WO2014188249A3

Abstract

A power conversion apparatus includes a primary side circuit, and a secondary side circuit that is magnetically coupled to the primary side circuit via a transformer. The primary side circuit or the secondary side circuit includes a first port, a second port, a first voltage part, a second voltage part, a voltage conversion unit that converts a voltage between the first voltage part and the second voltage part, and a switching unit that switches a connection state of the first port and the second port, and the voltage conversion unit between a first state in which the first port and the first voltage part are connected and the second port and the second voltage part are connected, and a second state in which the first port and the second voltage part are connected and the second port and the first voltage part are connected.

Description

POWER CONVERSION APPARATUS AND VOLTAGE CONVERSION METHOD

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] This invention relates to a technique of converting voltage.

2. Description of Related Art

[0002] A conventional power conversion apparatus can adjust an amount of power transmitted between a primary side port of a primary side circuit and a secondary side port of a secondary side circuit by changing a phase difference between switching of the primary side circuit and switching of the secondary side circuit (see Japanese Patent Application Publication No. 201 1 -193713 (JP 201 1 -193713 A), for example). This power conversion apparatus is a DC-DC converter capable of performing bi-directional step-up/step-down between a primary side port and a secondary side port.

[0003] However, since both the step-down direction and step-up direction are unidirectional between the two ports that are provided in the primary side circuit and between the two ports that are provided in secondary side circuit due to the configuration of the circuits, the voltage of one port must be higher than the voltage of the other port.

SUMMARY OF THE INVENTION

[0004] An object of this invention is to provide a power conversion apparatus and a voltage conversion method capable of alleviating the conditions that restrict the magnitude relation of the voltage between ports.

[0005] A first aspect of this invention is a power conversion apparatus including a primary side circuit, and a secondary side circuit that is magnetically coupled to the primary side circuit via a transformer, wherein the primary side circuit or the secondary side circuit includes a first port, a second port, a first voltage part, a second voltage part, a voltage conversion unit that converts a voltage between the first voltage part and the second voltage part, and a switching unit that switches a connection state of the first port and the second port, and the voltage conversion unit between a first state in which the first port and the first voltage part are connected and the second port and the second voltage part are connected, and a second state in which the first port and the second voltage part are connected and the second port and the first voltage part are connected.

[0006] A second aspect of this invention is a voltage conversion method of converting a voltage between a first port and a second port with a voltage conversion unit that converts a voltage between a first voltage part and a second voltage part, including switching a connection state of the first port and the second port, and the voltage conversion unit between a first state in which the first port and the first voltage part are connected and the second port and the second voltage part are connected, and a second state in which the first port and the second voltage part are connected and the second port and the first voltage part are connected.

[0007] According to the first and second aspects of this invention, it is possible to alleviate the conditions that restrict the magnitude relation of the voltage between ports.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1 is a block diagram showing an example of a configuration of a power supply apparatus serving as an embodiment of a power conversion apparatus according to the invention;

FIG. 2 is a block diagram showing an example of a configuration of a control unit according to this embodiment;

FIG. 3 is a timing chart showing an example of switching operations of a primary side circuit and a secondary side circuit according to this embodiment;

FIG. 4 is a block diagram showing an example of a configuration of the control unit according to this embodiment; and

FIG. 5 is a flowchart showing an example of a voltage conversion method according to the invention. DETAILED DESCRIPTION OF EMBODIMENTS

[0009] FIG. 1 is a block diagram showing an example of a configuration of a power supply apparatus 101 serving as an embodiment of a power conversion apparatus. For example, the power supply apparatus 101 is a power supply system that includes a power supply circuit 10, a control unit 50, and a sensor unit 70. The power supply apparatus 101 is a system, for example, that is installed in a vehicle such as an automobile, and supplies electric power to the respective on-vehicle loads.

[0010] For example, the power supply apparatus 101 includes, as primary side ports, a first input/output port 60a to which a primary side high voltage system load 61 a is connected and a second input/output port 60c to which a primary side low voltage system load 61c and a primary side low voltage system power supply 62c are connected. The primary side low voltage system power supply 62c supplies power to the primary side low voltage system load 61 c, which is operated by an identical voltage system (a 12 V system, for example) to the primary side low voltage system power supply 62c. Further, the primary side low voltage system power supply 62c supplies power stepped up by a primary side conversion circuit 20 provided in the power supply circuit 10 to the primary side high voltage system load 61a, which is operated by a different voltage system (a higher 48 V system than the 12 V system, for example) to the primary side low voltage system power supply 62c. A secondary battery such as a lead battery may be cited as a specific example of the primary side low voltage system power supply 62c.

[0011] For example, the power supply apparatus 101 includes, as secondary side ports, a third input/output port 60b to which a secondary side high voltage system load 61b and a secondary side high voltage system power supply 62b are connected and a fourth input/output port 60d to which a secondary side low voltage system load 61d is connected. The secondary side high voltage system power supply 62b supplies power to the secondary side high voltage system load 61b, which is operated by an identical voltage system (a higher 288 V system than the 12 V system and the 48 V system, for example) to the secondary side high voltage system power supply 62b. Further, the secondary side high voltage system power supply 62b supplies power stepped up by a secondary side conversion circuit 30 provided in the power supply circuit 10 to the secondary side low voltage system load 6 Id, which is operated by a different voltage system (a lower 72 V system than the 288 V system, for example) to the secondary side high voltage system power supply 62b. A secondary battery such as a lithium ion battery may be cited as a specific example of the secondary side high voltage system power supply 62b.

[0012] The power supply circuit 10 is a power conversion circuit that includes the four input/output ports described above and has functions for selecting two desired input/output ports from the four input/output ports and performing power conversion between the two selected input/output ports.

[0013] Port powers Pa, Pc, Pb, Pd are input/output powers (input powers or output powers) of the first input/output port 60a, the second input/output port 60c, the third input/output port 60b, and the fourth input/output port 60d, respectively. Port voltages Va, Vc, Vb, Vd are input/output voltages (input voltages or output voltages) of the first input/output port 60a, the second input/output port 60c, the third input/output port 60b, and the fourth input/output port 60d, respectively. Port currents la, Ic, lb, Id are input/output currents (input currents or output currents) of the first input/output port 60a, the second input/output port 60c, the third input/output port 60b, and the fourth input/output port 60d, respectively.

[0014] The power supply circuit 10 includes a capacitor C I provided in the first input/output port 60a, a capacitor C3 provided in the second input/output port 60c, a capacitor C2 provided in the third input/output port 60b, and a capacitor C4 provided in the fourth input/output port 60d. Film capacitors, aluminum electrolytic .capacitors, ceramic capacitors, polymer electrolytic capacitors, and so on may be cited as specific examples of the capacitors C I , C2, C3, C4.

[0015] The capacitor C I is inserted between a high potential side terminal 613 of the first input/output port 60a and a low potential side terminal 614 of the first input/output port 60a and the second input/output port 60c. The capacitor C3 is inserted between a high potential side terminal 616 of the second input/output port 60c and the low potential side terminal 614 of the first input/output port 60a and the second input/output port 60c. The capacitor C2 is inserted between a high potential side terminal 618 of the third input/output port 60b and a low potential side terminal 620 of the third input/output port 60b and the fourth input/output port 60d. The capacitor C4 is inserted between a high potential side terminal 622 of the fourth input/output port 60d and the low potential side terminal 620'of the third input/output port 60b and the fourth input/output port 60d.

[0016] The capacitors CI , C2, C3, C4 may be provided either inside or outside the power supply circuit 10.

[0017] The power supply circuit 10 is a power conversion circuit configured to include the primary side conversion circuit 20 and the secondary side conversion circuit 30. Note that the primary side conversion circuit 20 and the secondary side conversion circuit 30 are connected via a primary side magnetic coupling reactor 204 and a secondary side magnetic coupling reactor 304, and magnetically coupled by a transformer 400 (a center tapped transformer).

[0018] The primary side conversion circuit 20 is a primary side circuit configured to include a primary side full bridge circuit 200, the first input/output port 60a, and the second input/output port 60c. The primary side full bridge circuit 200 is a primary side power conversion unit configured to include a primary side coil 202 of the transformer 400, the primary side magnetic coupling reactor 204, a primary side first upper arm Ul , a primary side first lower arm /Ul , a primary side second upper arm V I , and a primary side second lower ami /VI . Here, the primary side first upper arm Ul , the primary side first lower arm /U 1 , the primary side second upper arm V 1 , and the primary side second lower arm V I are constituted by switching elements respectively configured to include, for example, an N channel type metal oxide semiconductor field effect transistor (MOSFET) and a body diode serving as a parasitic element of the MOSFET. Additional diodes may be connected to the MOSFET in parallel.

[0019] The primary side full bridge circuit 200 includes a primary side positive electrode bus line 298 connected to the high potential side terminal 613 of the first input/output port 60a, and a primary side negative electrode bus line 299 connected to the low potential side terminal 614 of the first input/output port 60a and the second input/output port 60c.

[0020] A primary side first arm circuit 207 connecting the primary side first upper arm Ul and the primary side first lower arm /Ul in series is attached between the primary side positive electrode bus line 298 and the primary side negative electrode bus line 299. The primary side first arm circuit 207 is a primary side first power conversion circuit unit (a primary side U phase power conversion circuit unit) capable of performing a power conversion operation by switching the primary side first upper arm Ul and the primary side first lower arm /Ul ON and OFF. Further, a primary side second ami circuit 21 1 connecting the primary side second upper arm V 1 and the primary side second lower arm /V I in series is attached between the primary side positive electrode bus line 298 and the primary side negative electrode bus line 299 in parallel with the primary side first arm circuit 207. The primary side second arm circuit 21 1 is a primary side second power conversion circuit unit (a primary side V phase power conversion circuit unit) capable of performing a power conversion operation by switching the primary side second upper arm V I and the primary side second lower ami /VI ON and OFF.

[0021] The primary side coil 202 and the primary side magnetic coupling reactor 204 are provided in a bridge part connecting a midpoint 207m of the primary side first arm circuit 207 to a midpoint 21 1 m of the primary side second arm circuit 21 1. To describe connection relationships to the bridge part in more detail, one end of a primary side first reactor 204a of the primary side magnetic coupling reactor 204 is connected to the midpoint 207m of the primary side first arm circuit 207, and one end of the primary side coil 202 is connected to another end of the primary side first reactor 204a. Further, one end of a primary side second reactor 204b of the primary side magnetic coupling reactor 204 is connected to another end of the primary side coil 202, and another end of the primary side second reactor 204b is connected to the midpoint 21 1m of the primary side second arm circuit 21 1. Note that the primary side magnetic coupling reactor 204 is configured to include the primary side first reactor 204a and the primary side second reactor 204b, which is magnetically coupled to the primary side first reactor 204a by a coupling coefficient ki .

[0022] The midpoint 207m is a primary side first intermediate node between the primary side first upper arm Ul and the primary side first lower ami AJl , and the midpoint 21 1 m is a primary side second intermediate node between the primary side second upper arm VI and the primary side second lower arm /V 1.

[0023] The first input/output port 60a is a port provided between the primary side positive electrode bus line 298 and the primary side negative electrode bus line 299. The first input/output port 60a is configured to include the terminal 613 and the terminal 614. The second input/output port 60c is a port provided between the primary side negative electrode bus line 299 and a center tap 202m of the primary side coil 202. The second input/output port 60c is configured to include the terminal 614 and the terminal 616.

[0024] The center tap 202m is connected to the high potential side terminal 616 of the second input/output port 60c. The center tap 202m is an intermediate connection point between a primary side first winding 202a and a primary side second winding 202b constituting the primary side coil 202.

[0025] The secondary side conversion circuit 30 is a secondary side circuit configured to include a secondary side full bridge circuit 300, the third input/output port 60b, and the fourth input/output port 60d. The secondary side full bridge circuit 300 is a secondary side power conversion unit configured to include a secondary side coil 302 of the transformer 400, the secondary side magnetic coupling reactor 304, a secondary side first upper arm U2, a secondary side first lower arm /U2, a secondary side second upper arm V2, and a secondary side second lower arm /V2. Here, the secondary side first upper am U2, the secondary side first lower am /U2, the secondary side second upper arm V2, and the secondary side second lower arm /V2 are constituted by switching elements respectively configured to include, for example, an N channel type MOSFET and a body diode serving as a parasitic element of the MOSFET. Additional diodes may be connected to the MOSFET in parallel.

[0026] The secondary side full bridge circuit 300 includes a secondary side positive electrode bus line 398 connected to the high potential side terminal 618 of the third input/output port 60b, and a secondary side negative electrode bus line 399 connected to the low potential side terminal 620 of the third input/output port 60b and the fourth input/output port 60d.

[0027] A secondary side first arm circuit 307 connecting the secondary side first upper arm U2 and the secondary side first lower arm /U2 in series is attached between the secondary side positive electrode bus line 398 and the secondary side negative electrode bus line 399. The secondary side first arm circuit 307 is a secondary side first power conversion circuit unit (a secondary side U phase power conversion circuit unit) capable of performing a power conversion operation by switching the secondary side first upper arm U2 and the secondary side first lower arm /U2 ON and OFF. Further, a secondary side second arm circuit 31 1 connecting the secondary side second upper ann V2 and the secondary side second lower ann /V2 in series is attached between the secondary side positive electrode bus line 398 and the secondary side negative electrode bus line 399 in parallel with the secondary side first ann circuit 307. The secondary side second arm circuit 31 1 is a secondary side second power conversion circuit unit (a secondary side V phase power conversion circuit unit) capable of performing a power conversion operation by switching the secondary side second upper ann V2 and the secondary side second lower ann /V2 ON and OFF.

[0028] The secondary side coil 302 and the secondary side magnetic coupling reactor 304 are provided in a bridge part connecting a midpoint 307m of the secondary side first arm circuit 307 to a midpoint 311m of the secondary side second arm circuit 31 1. To describe connection relationships to the bridge part in more detail, one end of a secondary side first reactor 304a of the secondary side magnetic coupling reactor 304 is connected to the midpoint 307m of the secondary side first arm circuit 307, and one end of the secondary side coil 302 is connected to another end of the secondary side first reactor 304a. Further, one end of a secondary side second reactor 304b of the secondary side magnetic coupling reactor 304 is connected to another end of the secondary side coil 302, and another end of the secondary side second reactor 304b is connected to the midpoint 31 1m of the secondary side second arm circuit 31 1. Note that the secondary side magnetic coupling reactor 304 is configured to include the secondary side first reactor 304a and the secondary side second reactor 304b, which is magnetically coupled to the secondary side first reactor 304a by a coupling coefficient k₂.

[0029] The midpoint 307m is a secondary side first intermediate node between the secondary side first upper arm U2 and the secondary side first lower arm U2, and the midpoint 31 1m is a secondary side second intermediate node between the secondary side second upper arm V2 and the secondary side second lower ami /V2.

[0030] The third input/output port 60b is a port provided between the secondary side positive electrode bus line 398 and the secondary side negative electrode bus line 399. The third input/output port 60b is configured to include the terminal 618 and the terminal 620. The fourth input/output port 60d is a port provided between the secondary side negative electrode bus line 399 and a center tap 302m of the secondary side coil 302. The fourth input/output port 60d is configured to include the terminal 620 and the terminal 622.

[0031] The center tap 302m is connected to the high potential side terminal 622 of the fourth input/output port 60d. The center tap 302m is an intermediate connection point between a secondary side first winding 302a and a secondary side second winding 302b constituting the secondary side coil 302.

[0032] In FIG. 1 , the power supply apparatus 101 includes the sensor unit 70. The sensor unit 70 serves as detecting means that detects an input/output value Y of at least one of the first to fourth input/output ports 60a, 60c, 60b, 60d at predetermined detection period intervals and outputs a detection value Yd corresponding to the detected input/output value Y to the control unit 50. The detection value Yd may be a detected voltage obtained by detecting the input/output voltage, a detected current obtained by detecting the input/output current, or a detected power obtained by detecting the input/output power. The sensor unit 70 may be provided either inside or outside the power supply circuit 10.

[0033] The sensor unit 70 includes, for example, a voltage detection unit that detects the input/output voltage generated in at least one of the first to fourth input/output ports 60a, 60c, 60b, 60d. For example, the sensor unit 70 includes a primary side voltage detection unit that outputs at least one detected voltage from among an input/output voltage Va and an input/output voltage Vc as a primary side voltage detection value, and a secondary side voltage detection unit that outputs at least one detected voltage from among an input/output voltage Vb and an input/output voltage Vd as a secondary side voltage detection value.

(0034] The voltage detection unit of the sensor unit 70 includes, for example, a voltage sensor that monitors an input/output voltage value of at least one port, and a voltage detection circuit that outputs a detected voltage corresponding to the input/output voltage value monitored by the voltage sensor to the control unit 50.

[0035] The sensor unit 70 includes, for example, a current detection unit that detects the input/output current flowing through at least one of the first to fourth input/output ports 60a, 60c, 60b, 60d. For example, the sensor unit 70 includes a primary side current detection unit that outputs at least one detected current from among an input/output current la and an input/output current Ic as a primary side current detection value, and a secondary side current detection unit that outputs at least one detected current from among an input/output current lb and an input/output current Id as a secondary side current detection value.

[0036] The current detection unit of the sensor unit 70 includes, for example, a current sensor that monitors an input/output current value of at least one port, and a current detection circuit that outputs a detected current corresponding to the input/output current value monitored by the current sensor to the control unit 50.

[0037] The power supply apparatus 101 includes the control unit 50. For example, the control unit 50 is an electronic circuit that includes a microcomputer having an inbuilt central processing unit (CPU). The control unit 50 may be provided either inside or outside the power supply circuit 10.

[0038] The control unit 50 feedback-controls a power conversion operation performed by the power supply circuit 10 such that the detected value Yd of the input/output value Y of at least one of the first to fourth input/output ports 60a, 60c, 60b, 60d converges to a target value Yo set in the port. For example, the target value Yo is a command value set by the control unit 50 or a predetermined apparatus other than the control unit 50 on the basis of driving conditions defined in relation to the respective loads (the primary side low voltage system load 61c and so on, for example) connected to the input/output ports. The target value Yo functions as an output target value when power is output from the port and an input target value when power is input into the port, and may be a target voltage value, a target current value, or a target power value.

[0039] Further, the control unit 50 feedback-controls the power conversion operation performed by the power supply circuit 10 such that a transmitted power P transmitted between the primary side conversion circuit 20 and the secondary side conversion circuit 30 via the transformer 400 converges to a set target transmitted power Po. The transmitted power will also be referred to as a power transmission amount. For example, the target transmitted power Po is a command value set by the control unit 50 or a predetermined apparatus other than the control unit 50 on the basis of a deviation between the detected value Yd and the target value Yo in one of the ports.

[0040] The control unit 50 feedback-controls the power conversion operation performed by the power supply circuit 10 by varying a value of a predetermined control parameter X, and is thus capable of adjusting the respective input/output values Y of the first to fourth input/output ports 60a, 60c, 60b, 60d of the power supply circuit 10. Two control variables, namely a phase difference φ and a duty ratio D (an ON time δ) are used as the main control parameters X.

[0041] The phase difference φ is a deviation (a time lag) between switching timings of identical-phase power conversion circuit units of the primary side full bridge circuit 200 and the secondary side full bridge circuit 300. The duty ratio D (the ON time δ) is a duty ratio (an ON time) between switching waveforms of the respective power conversion circuit units constituting the primary side full bridge circuit 200 and the secondary side full bridge circuit 300.

[0042] The two control parameters X can be controlled independently of each other. The control unit 50 varies the input/output values Y of the respective input/output ports of the power supply circuit 10 by performing duty ratio control and/or phase control on the primary side full bridge circuit 200 and the secondary side full bridge circuit 300 using the phase difference φ and the duty ratio D (the ON time δ).

[0043] FIG. 2 is a block diagram of the control unit 50. The control unit 50 is a control unit having a function for performing switching control on the respective switching elements of the primary side conversion circuit 20, such as the primary side first upper arm Ul , and the respective switching elements of the secondary side conversion circuit 30, such as the secondary side first upper arm U2. The control unit 50 is configured to include a power conversion mode determination processing unit 502, a phase difference φ determination processing unit 504, an ON time δ determination processing unit 506, a primary side switching processing unit 508, and a secondary side switching processing unit 510. For example, the control unit 50 is an electronic circuit that includes a microcomputer having an inbuilt CPU.

[0044] For example, the power conversion mode determination processing unit 502 selects and sets an operating mode from among power conversion modes A to L of the power supply circuit 10, to be described below, on the basis of a predetermined external signal (for example, a signal indicating the deviation between the detected value Yd and the target value Yo in one of the ports). As regards the power conversion modes, in mode A, power input from the first input/output port 60a is converted and output to the second input/output port 60c. In mode B, power input from the first input/output port 60a is converted and output to the third input/output port 60b. In mode C, power input from the first input/output port 60a is converted and output to the fourth input/output port 60d.

[0045] In mode D, power input from the second input/output port 60c is converted and output to the first input/output port 60a. In mode E, power input from the second input/output port 60c is converted and output to the third input/output port 60b. In mode F, power input from the second input/output port 60c is converted and output to the fourth input/output port 60d.

[0046] In mode G, power input from the third input/output port 60b is converted and output to the first input/output port 60a. In mode H, power input from the third input/output port 60b is converted and output to the second input/output port 60c. In mode I, power input from the third input/output port 60b is converted and output to the, fourth input/output port 60d.

[0047] In mode J, power input from the fourth input/output port 60d is converted and output to the first input/output port 60a. In mode K, power input from the fourth input/output port 60d is converted and output to the second input/output port 60c. In mode L, power input from the fourth input/output port 60d is converted and output to the third input/output port 60b.

[0048] The phase difference φ determination processing unit 504 has a function for setting a phase difference φ between switching period motions of the switching elements between the primary side conversion circuit 20 and the secondary side conversion circuit 30 in order to cause the power supply circuit 10 to function as a (DC-DC) converter circuit.

[0049] The ON time δ determination processing unit 506 has a function for setting an ON time δ of the switching elements of the primary side conversion circuit 20 and the secondary side conversion circuit 30 in order to cause the primary side conversion circuit 20 and the secondary side conversion circuit 30 to function respectively as step-up/step-down circuits.

[0050] The primary side switching processing unit 508 has a function for performing switching control on the respective switching elements constituted by the primary side first upper arm Ul , the primary side first lower arm /U l , the primary side second upper arm VI , and the primary side second lower arm /V I , on the basis of outputs of the power conversion mode determination processing unit 502, the phase difference φ determination processing unit 504, and the ON time δ determination processing unit 506.

[0051] The secondary side switching processing unit 510 has a function for performing switching control on the respective switching elements constituted by the secondary side first upper arm U2, the secondary side first lower arm /U2, the secondary side second upper arm V2, and the secondary side second lower arm /V2, on the basis of the outputs of the power conversion mode determination processing unit 502, the phase difference φ determination processing unit 504, and the ON time δ determination processing unit 506.

[0052] An operation of the power supply apparatus 101 having the above configuration will now be described using FIGS. 1 and 2. When, for example, an external signal requesting an operation in which the power conversion mode of the power supply circuit 10 is set at mode F is input, the power conversion mode determination processing unit 502 of the control unit 50 sets the power conversion mode of the power supply circuit 10 to mode F. At this time, a voltage input into the second input/output port 60c is stepped up by a step-up function of the primary side conversion circuit 20, whereupon power having the stepped-up voltage is transmitted to the third input/output port 60b side by a DC-DC converter circuit function of the power supply circuit 10, stepped down by a step-down function of the secondary side conversion circuit 30, and then output from the fourth input/output port 60d.

[0053] Here, a step-up/step-down function of the primary side conversion circuit 20 will be described in detail. Focusing on the second input/output port 60c and the first input/output port 60a, the terminal 616 of the second input/output port 60c is connected to the midpoint 207m of the primary side first arm circuit 207 via the primary side first winding 202a and the primary side first reactor 204a connected in series to the primary side first winding 202a. Respective ends of the primary side first arm circuit 207 are connected to the first input/output port 60a, and as a result, a step-up/step-down circuit is attached between the terminal 616 of the second input/output port 60c and the first input/output port 60a.

[0054] The terminal 616 of the second input/output port 60c is also connected to the midpoint 21 1m of the primary side second arm circuit 211 via the primary side second winding 202b and the primary side second reactor 204b connected in series to the primary side second winding 202b. Respective ends of the primary side second arm circuit 211 are connected to the first input/output port 60a, and as a result, a step-up/step-down circuit is attached in parallel between the terminal 616 of the second input/output port 60c and the first input/output port 60a. Note that since the secondary side conversion circuit 30 is a circuit having a substantially identical configuration to the primary side conversion circuit 20, two step-up/step-down circuits are likewise connected in parallel between the terminal 622 of the fourth input/output port 60d and the third input/output port 60b. Hence, the secondary side conversion circuit 30 has an identical step-up/step-down function to the primary side conversion circuit 20.

[0055] Next, the function of the power supply circuit 10 as a DC-DC converter circuit will be described in detail. Focusing on the first input/output port 60a and the third input/output port 60b, the primary side full bridge circuit 200 is connected to the first input/output port 60a, and the secondary side full bridge circuit 300 is connected to the third input/output port 60b. When the primary side coil 202 provided in the bridge part of the primary side full bridge circuit 200 and the secondary side coil 302 provided in the bridge part of the secondary side full bridge circuit 300 are magnetically coupled by a coupling coefficient k-r, the transformer 400 functions as a center tapped transformer having a number of windings 1 : N. Hence, by adjusting the phase difference φ between the switching period motions of the switching elements in the primary side full bridge circuit 200 and the secondary side full bridge circuit 300, power input into the first input/output port 60a can be converted and transmitted to the third input/output port 60b or power input into the third input/output port 60b can be converted and transmitted to the first input/output port 60a.

[0056] FIG. 3 is a view showing a timing chart of ON/OFF switching waveforms of the respective arms provided in the power supply circuit 10 resulting from control executed by the control unit 50. In FIG. 3, Ul is an ON/OFF waveform of the primary side first upper arm Ul , V I is an ON/OFF waveform of the primary side second upper arm V I , U2 is an ON/OFF waveform of the secondary side first upper arm U2, and V2 is an ON/OFF waveform of the secondary side second upper arm V2. ON/OFF waveforms of the primary side first lower arm Ul , the primary side second lower arm /VI , the secondary side first lower arm U2, and the secondary side second lower ami /V2 are inverted waveforms (not shown) obtained by respectively inverting the ON/OFF waveforms of the primary side first upper arm U 1 , the primary side second upper arm V 1 , the secondary side first upper ami U2, and the secondary side second upper arm V2. Note that dead time is preferably provided between the respective ON/OFF wavefonris of the upper and lower arms to prevent a through current from flowing when both the upper and lower arms are switched ON. Further, in FIG. 3, a high level indicates an ON condition and a low level indicates an OFF condition.

[0057] Here, by modifying the respective ON times δ of Ul , VI , U2, and V2, step-up/step-down ratios of the primary side conversion circuit 20 and the secondary side conversion circuit 30 can be modified. For example, by making the respective ON times δ of U l , VI , U2, and V2 equal to each other, the step-up/step-down ratio of the primary side conversion circuit 20 can be made equal to the step-up/step-down ratio of the secondary side conversion circuit 30.

[0058] The ON time δ determination processing unit 506 make the respective ON times δ of Ul , VI , U2, and V2 equal to each other (respective ON times δ = primary side ON time 611 = secondary side ON time δ12 = time value a) so that the respective step-up/step-down ratios of the primary side conversion circuit 20 and the secondary side conversion circuit 30^" are equal to each other.

[0059] The step-up/step-down ratio of the primary side conversion circuit 20 is determined by the duty ratio D, which is a proportion of a switching period T of the switching elements (arms) constituting the primary side full bridge circuit 200 occupied by the ON time δ. Similarly, the step-up/step-down ratio of the secondary side conversion circuit 30 is determined by the duty ratio D, which is a proportion of the switching period T of the switching elements (arms) constituting the secondary side full bridge circuit 300 occupied by the ON time δ. The step-up/step-down ratio of the primary side conversion circuit 20 is a transformation ratio between the first input/output port 60a and the second input/output port 60c, while the step-up/step-down ratio of the secondary side conversion circuit 30 is a transformation ratio between the third input/output port 60b and the fourth input/output port 60d.

[0060] Therefore, for example,

the step-up/step-down ratio of the primary side conversion circuit 20

= the voltage of the second input/output port 60c / the voltage of the first input/output port 60a

= 51 1 / T = oc / T,

and the step-up/step-down ratio of the secondary side conversion circuit 30

= the voltage of the fourth input/output port 60d / the voltage of the third input/output port 60b

= δ12 / Τ = α / Τ.

In other words, the respective step-up/step-down ratios of the primary side conversion circuit 20 and the secondary side conversion circuit 30 take identical values (= a / T).

[0061] Note that the ON time δ in FIG. 3 represents both the ON time 61 1 of the primary side first upper arm Ul l and the primary side second upper arm V I and the ON time 512 of the secondary side first upper arm U2 and the secondary side second upper arm V2. Further, the switching period T of the arms constituting the primary side full bridge circuit 200 and the switching period T of the arms constituting the secondary side full bridge circuit 300 are equal times.

[0062] Furthermore, a phase difference between Ul and V I is activated at 180 degrees (π), and a phase difference between U2 and V2 is likewise activated at 180 degrees (π). Moreover, by changing the phase difference φ between Ul and U2, the power transmission amount P between the primary side conversion circuit 20 and the secondary side conversion circuit 30 can be adjusted such that when the phase difference φ > 0, power can be transmitted from the primary side conversion circuit 20 to the secondary side conversion circuit 30, and when the phase difference φ < 0, power can be transmitted from the secondary side conversion circuit 30 to the primary side conversion circuit 20.

[0063] The phase difference φ is a deviation (a time lag) between the switching timings of identical-phase power conversion circuit units of the primary side full bridge circuit 200 and the secondary side full bridge circuit 300. For example, the phase difference φ is a deviation between the switching timings of the primary side first arm circuit 207 and the secondary side first arm circuit 307, and a deviation between the switching timings of the primary side second arm circuit 21 1 and the secondary side second arm circuit 31 1. These deviations are controlled to be equal to each other. In other words, the phase difference φ between Ul and U2 and the phase difference φ between V I and V2 are controlled to identical values.

[0064] Hence, when, for example, an external signal requesting an operation in which the power conversion mode of the power supply circuit 10 is set at mode F is input, the power conversion mode determination processing unit 502 selects and sets mode F. The ON time δ determination processing unit 506 then sets the ON time δ to define a step-up ratio required when the primary side conversion circuit 20 is caused to function as a step-up circuit that steps up the voltage input into the second input/output port 60c and outputs the stepped-up voltage to the first input/output port 60a. Note that the secondary side conversion circuit 30 functions as a step-down circuit that steps down the voltage input into the third input/output port 60b at a step-down ratio defined in accordance with the ON time δ set by the ON time δ determination processing unit 506, and outputs the stepped-down voltage to the fourth input/output port 60d. Further, the phase difference φ determination processing unit 504 sets the phase difference φ such that the power input into the first input/output port 60a is transmitted to the third input/output port 60b in the desired power transmission amount P.

[0065] The primary side switching processing unit 508 performs switching control on the respective switching elements constituted by the primary side first upper arm Ul , the primary side first lower arm /Ul , the primary side second upper arm VI , and the primary side second lower arm /V I to cause the primary side conversion circuit 20 to function as a step-up circuit and to cause the primary side conversion circuit 20 to function as a part of a DC-DC converter circuit.

[0066] The secondary side switching processing unit 510 performs switching control on the respective switching elements constituted by the secondary side first upper arm U2, the secondary side first lower arm U2, the secondary side second upper arm V2, and the secondary side second lower arm /V2 to cause the secondary side conversion circuit 30 to function as a step-down circuit and to cause the secondary side conversion circuit 30 to function as a part of a DC-DC converter circuit. [0067] As described above, the primary side conversion circuit 20 and the secondary side conversion circuit 30 can be caused to function as a step-up circuit or a step-down circuit, and the power supply circuit 10 can be caused to function as a bidirectional DC-DC converter circuit. Therefore, power conversion can be performed in all of the power conversion modes A to L, or in other words, power conversion can be performed between two input/output ports selected from the four input/output ports.

[0068] The transmitted power P (also referred to as the power transmission amount P) adjusted by the control unit 50 in accordance with the phase difference φ is power transmitted from one of the primary side conversion circuit 20 and the secondary side conversion circuit 30 to the other via the transformer 400, and is expressed as

P = (N x Va x Vb) / (π x ω x L) x F (D, φ) Equation 1

[0069] Note that N is a winding ratio of the transformer 400, Va is the input/output voltage of the first input/output port 60a, Vb is the input/output voltage of the third input/output port 60b, π is pi, ω (= 2π x f = 2π / T) is an angular frequency of the switching operations of the primary side conversion circuit 20 and the secondary side conversion circuit 30, f is a switching frequency of the primary side conversion circuit 20 and the secondary side conversion circuit 30, T is the switching period of the primary side conversion circuit 20 and the secondary side conversion circuit 30, L is an equivalent inductance of the magnetic coupling reactors 204, 304 and the transformer 400 relating to power transmission, and F (D, φ) is a function having the duty ratio D and the phase difference φ as variables and a variable that increases monotonically as the phase difference φ increases, independently of the duty ratio D. The duty ratio D and the phase difference φ are control parameters designed to vary within a range sandwiched between predetermined upper and lower limit values.

[0070] The control unit 50 adjusts the transmitted power P by changing the phase difference φ such that a port voltage Vp of at least one predetermined port from among the primary side ports and the secondary side ports converges to the target port voltage Vo. Therefore, even when a current consumption of the load connected to the predetermined port increases, the control unit 50 can prevent the port voltage Vp from dropping relative to the target port voltage Vo by varying the phase difference φ in order to adjust the transmitted power P.

[0071] For example, the control unit 50 adjusts the transmitted power P by changing the phase difference φ such that the port voltage Vp in one port serving as a transmission destination of the transmitted power P, from among the primary side ports and the secondary side ports, converges to the target port voltage Vo. Therefore, even when the current consumption of the load connected to the port serving as the transmission destination of the transmitted power P increases, the control unit 50 can prevent the port voltage Vp from dropping relative to the target port voltage Vo by increasing the phase difference φ in order to adjust the transmitted power P in an increasing direction.

[0072] Meanwhile, the power supply circuit 10 is a DC-DC converter capable of performing bi-directional step-up/step-down between the primary side conversion circuit 20 and the secondary side conversion circuit 30. Nevertheless, due to the configuration of the primary side full bridge circuit 200, the step-up direction and the step-down direction between the first input/output port 60a and the second input/output port 60c are mutually opposite unilateral directions. That is, the step-up direction is fixed to one direction, and the step-down direction is also fixed to one direction that is opposite to the step-up direction. Hence, if no measures are taken, the port voltage Va must constantly be larger than the port voltage Vc.

[0073] Thus, as a measure to deal with the foregoing problem, the primary side conversion circuit 20 includes a switching circuit 213 as a switching unit that switches the connection state of the first input/output port 60a and the second input/output port 60c and the primary side full bridge circuit 200 between a first state A and a second state B. The switching operation of the switching circuit 213 is controlled by the control unit 50.

[0074] The primary side full bridge circuit 200 is a voltage conversion unit that converts the voltage between the first voltage part and the second voltage part, and is a step-up/step-down unit that steps down the voltage of the first voltage part and outputs the stepped-down voltage to the second voltage part or step up the voltage of the second voltage part and outputs the stepped-up voltage to the first voltage part. FIG. 1 illustrates a capacitor C I as the first voltage part, and illustrates a capacitor C3 as the second voltage part. The capacitor C I is a high voltage part to which a high potential primary side positive electrode bus line 298 is connected, and the capacitor C3 is a low voltage part to which a low potential primary side positive electrode bus line 297 and a center tap 202m are connected.

[0075] The first state A is a state in which the first input/output port 60a and the capacitor C I are connected and the second input/output port 60c and the capacitor C3 are connected. The second state B is a state in which the first input/output port 60a and the capacitor C3 are connected and the second input/output port 60c and the capacitor C I are connected. The first state A is illustrated in FIG. 1 .

[0076] The switching circuit 213 includes, for example, a switch 214 that switches the connection destination of the first input/output port 60a, and a switch 215 that switches the connection destination of the second input/output port 60c. The switch 214 switches the connection destination of the first input/output port 60a to either the capacitor C I or the capacitor C3, and the switch 215 switches the connection destination of the second input/output port 60c to either the capacitor C I or the capacitor C3.

[0077] When the connection state is switched to the first state A by the switching circuit 213, the connection destination of the first input/output port 60a is switched to the capacitor C I by the switch 214, and the connection destination of the second input/output port 60c is switched to the capacitor C3 by the switch 215. When the connection state is switched to the second state B by the switching circuit 21 3, the connection destination of the first input/output port 60a is switched to the capacitor C3 by the switch 214, and the connection destination of the second input/output port 60c is switched to the capacity C 1 by the switch 215.

[0078] The switching circuit 213 is inserted between the input/output ports 60a, 60c and the capacitors C I , C3. The switch 214 is inserted between the terminal 613 and the capacitor C I in the primary side positive electrode bus line 298, and the switch 215 is inserted between the terminal 616 and the capacitor C3 in the primary side positive electrode bus line 297. Specific examples of the switches 214, 215 are switching elements such as transistors.

[0079] Accordingly, as a result of the primary side conversion circuit 20 including the switching circuit 213, the conditions that restrict the magnitude relation of the voltage of the first input/output port 60a and the voltage of the second input/output port 60c can be alleviated. That is, the port voltage Va may be larger than the port voltage Vc, or the port voltage Vc may be larger than the port voltage Va.

[0080] For example, even when the voltage of the second input/output port 60c rises and becomes higher than the voltage of the first input/output port 60a, as a result of the connection state being switched to the second state B, the primary side full bridge circuit 200 can perform voltage conversion between the first input/output port 60a and the second input/output port 60c. Similarly, even when the voltage of the first input/output port 60a drops and becomes lower than the voltage of the second input/output port 60c, as a result of the connection state being switched to the second state B, the primary side full bridge circuit 200 can perform voltage conversion between the first input/output port 60a and the second input/output port 60c.

[0081] By providing the switching circuit 213 in the primary side conversion circuit 20, for example, the power supply apparatus 101 can be used for the application in which the magnitude relation of the voltage of the first input/output port 60a and the voltage of the second input/output port 60c is reversed at an arbitrary timing. For example, the power supply apparatus 101 can be used for the application in which the lower limit of the variable range of the port voltage Va is higher than the lower limit of the variable range of the port voltage Vc, or the application in which the upper limit of the variable range of the port voltage Va is lower than the upper limit of the variable range of the port voltage Vc.

[0082] The variable range of the port voltage Va corresponds, for example, to the voltage range that may be adopted by the target port voltage Vao in the first input/output port 60a, and the variable range of the port voltage Vc corresponds, for example, to the voltage range that may be adopted by the target port voltage Vco in the second input/output port 60c. Moreover, the target port voltage Vao is set to a predetermined constant value (for example, 15 V), and the target port voltage Vco is set to a predetermined voltage range (for example, 10 V or more and 20 V or less) including that constant value. Otherwise, the target port voltage Vco may be set to a constant value (for example, 15 V), and the target port voltage Vao may be set to a predetermined voltage range (for example, 10 V or more and 20 V or less) including that constant value.

[0083] When the switching circuit 213 switches the connection state to the first state A, the primary side full bridge circuit 200 can step down the port voltage Va of the first input/output port 60a and output the stepped-down voltage to the second input/output port 60c. That is, the first state A in the foregoing case is a step-down operation state A l in which the port voltage Va of the first input/output port 60a is stepped down by the primary side full bridge circuit 200 and output to the second input/output port 60c.

[0084] Otherwise, when the switching circuit 213 switches the connection state to the first state A, the primary side full bridge circuit 200 can step up the port voltage Vc of the second input/output port 60c and output the stepped-up voltage to the first input/output port 60a. That is, the first state A in the foregoing case is a step-up operation state A2 in which the port voltage Vc of the second input/output port 60c is stepped up by the primary side full bridge circuit 200 and output to the first input/output port 60a.

[0085] Meanwhile, when the switching circuit 213 switches the connection state to the second state B, the primary side full bridge circuit 200 can step up the port voltage Va of the first input/output port 60a and output the stepped-up voltage to the second input/output port 60c. That is, the second state B in the foregoing case is a step-up operation state Bl in which the port voltage Va of the first input/output port 60a is stepped up by the primary side full bridge circuit 200 and output to the second input/output port 60c.

[0086] Otherwise, when the switching circuit 213 switches the connection state to the second state B, the primary side full bridge circuit 200 can step down the port voltage Vc of the second input/output port 60c and output the stepped-down voltage to the first input/output port 60a. That is, the second state B in the foregoing case is a step-down operation state B2 in which the port voltage Vc of the second input/output port 60c is stepped down by the primary side full bridge circuit 200 and output to the first input/output port 60a.

[0087] FIG. 4 is a block diagram showing an example of a configuration of the control unit 50. The control unit 50 includes a PID control unit 51 , a comparator 54, and a control switching unit 55.

[0088] The PID control unit 51 includes a phase difference command value generation unit 52 that generates, through PID control performed at intervals of the switching period T, a command value φο of the phase difference φ for causing a port voltage Vpl of a first port, from among the ports serving as the transmission destinations of the transmitted power P, to converge to a first target voltage Vol .

[0089] For example, the phase difference command value generation unit 52 of the PID control unit 51 generates the command value φο of the phase difference φ to cause the port voltage Va of the first input/output port 60a, which constitutes a high potential side port of the ports serving as the transmission destinations of the transmitted power P, to converge to the target port voltage Vao. The phase difference command value generation unit 52 performs PID control on the basis of a deviation between the target port voltage Vao of the port voltage Va and a detected voltage Vad of the port voltage Va, which is obtained by the sensor unit 70, in order to generate a command value φο for causing this deviation to converge to zero at intervals of the switching period T.

[0090] The control unit 50 adjusts the transmitted power P such that the port voltage Vpl converges to the first target voltage Vol by performing switching control on the primary side conversion circuit 20 and the secondary side conversion circuit 30 in accordance with the command value φο generated by the PID control unit 51. For example, the control unit 50 adjusts the transmitted power P determined in accordance with Equation 1 by modifying the command value φο of the phase difference φ such that the detected voltage Vad of the port voltage Va converges to the target port voltage Vao of the port voltage Va.

[0091] The PID control unit 51 also includes a duty ratio command value generation unit 53 that generates, through PID control performed at intervals of the switching period T, a command value Do of the duty ratio D for causing a port voltage Vp2 of a second port, from among the ports serving as the transmission destinations of the transmitted power P, to converge to a second target voltage Vo2.

[0092] For example, the duty ratio command value generation unit 53 of the PID control unit 51 generates the command value Do of the duty ratio D to cause the port voltage Vc of the second input/output port 60c, which constitutes a low potential side port of the ports serving as the transmission destinations of the transmitted power P, to converge to the target port voltage Vco. The duty ratio command value generation unit 53 performs PID control on the basis of a deviation between the target port voltage Vco of the port voltage Vc and a detected voltage Vcd of the port voltage Vc, which is obtained by the sensor unit 70, in order to generate a command value Do for causing this deviation to converge to zero at intervals of the switching period T.

[0093] The control unit 50 adjusts a step-up/step-down ratio such that the port voltage Vp2 converges to the second target voltage Vo2 by performing switching control on the primary side conversion circuit 20 and the secondary side conversion circuit 30 in accordance with the command value Do generated by the PID control unit 51. This step-up/step-down ratio is a transformation ratio between the first port and the second port of the ports serving as the transmission destinations of the transmitted power P. For example, the control unit 50 adjusts the step-up/step-down ratio between the first input/output port 60a and the second input/output port 60c by modifying the command value Do of the duty ratio D such that the detected voltage Vcd of the port voltage Vc converges to the target port voltage Vco of the port voltage Vc.

[0094] Note that the PID control unit 51 may include an ON time command value generation unit that generates a command value δο of the ON time δ instead of the command value Do of the duty ratio D.

[0095] FIG. 4 shows an example of the switching circuit 213 and the control switching unit 55 selectively switching between the step-down operation state Al in which the port voltage Va is stepped down and output to the second input/output port 60c, and the step-up operation state Bl in which the port voltage Va is stepped up and output to the second input/output port 60c. That is, FIG. 4 shows a case where the second input/output port 60c that functions as the output port that outputs the voltage after being subject to voltage conversion in both the step-down operation state Al and the step-up operation state B l .

[0096] The control unit 50 controls the step-up/step-down performed by the primary side full bridge circuit 200 according to the voltage of the second input/output port 60c that functions as the output port that outputs the voltage after being subject to voltage conversion. The control unit 50 controls the step-up/step-down performed by the primary side full bridge circuit 200 according to the deviation between the target port voltage Vco of the port voltage Vc of the second input/output port 60c and the detection voltage Vcd of the port voltage Vc acquired by the sensor unit 70.

[0097] The switching circuit 213 switches the connection state to either the first state A or the second state B according to the target port voltage Vao in the first input/output port 60a and the target port voltage Vco in the second input/output port 60c. For example, the comparator 54 compares the target port voltage Vao and the target port voltage Vco, and the switching circuit 213 switches the connection destination of the first input/output port 60a and the second input/output port 60c according to the comparison result.

[0098] The control switching unit 55 switches the step-up/step-down operation of the primary side full bridge circuit 200 to either the step-down operation or the step-up operation according to the target port voltage Vao in the first input/output port 60a and the target port voltage Vco in the second input/output port 60c. For example, the comparator 54 compares the target port voltage Vao and the target port voltage Vco, and the control switching unit 55 switches the step-up/step-down operation of the primary side full bridge circuit 200 according to the comparison result.

[0099] Moreover, the control switching unit 55 switches the target to be controlled according to the ON time δ that is determined according to the command value Do generated by the duty ratio command value generation unit 53 from one arm of the upper and lower arms, which perform voltage conversion of the port voltage Va, to the other arm. In FIG. 1 , the upper arm in the foregoing case corresponds to the primary side first upper arm Ul and the primary side second upper arm VI , and the lower arm in the foregoing case corresponds to the primary side first lower arm /U l and the primary side second lower arm VI .

[0100] The duty ratio command value generation unit 53 generates the command value Do that increases the duty ratio D so that the ON time δ of the upper arm or the lower arm is extended as the detection voltage Vcd of the port voltage Vc is lower relative to the target port voltage Vco.

[0101] Accordingly, the control unit 50 can operate the primary side full bridge circuit 200 so that the port voltage Va is stepped down by turning ON/OFF the primary side first upper arm Ul and the primary side second upper arm V I according to the command value Do in a state where the connection state is switched to the first state A. In addition, as a result of extending the ON time δ of the upper arms Ul , V I according to the command value Do in the primary side full bridge circuit 200 that functions as a step-down circuit of the port voltage Va, the port voltage Vc can be raised to approach the target port voltage Vco.

[0102] Meanwhile, the control unit 50 can operate the primary side full bridge circuit 200 so that the port voltage Va is stepped up by turning ON/OFF the primary side first lower arm /Ul and the primary side second lower arm /VI according to the common command value Do in a state where the connection state is switched to the second state B. In addition, as a result of extending the ON time δ of the lower arms /Ul , /VI according to the command value Do in the primary side full bridge circuit 200 that functions as a step-up circuit of the port voltage Va, the port voltage Vc can be raised to approach the target port voltage Vco.

[0103] FIG. 5 is a flowchart showing an example of a voltage conversion method. The voltage conversion method shown in FIG. 5 is executed by the control unit 50.

[0104] In step S 10, the comparator 54 determines the magnitude relation of the target port voltage Vao of the port voltage Va and the target port voltage Vco of the port voltage Vc. When the comparator 54 determines that the target port voltage Vao is greater than the target port voltage Vco, the control unit 50 executes the processing of steps S20 and S30. Meanwhile, when the comparator 54 determines that the target port voltage Vao is smaller than the target port voltage Vco, the control unit 50 executes the processing of steps S40 and S50.

[0105] When the target port voltage Vao is higher than the target port voltage Vco, the control switching unit 55 switches the step-up/step-down operation of the primary side full bridge circuit 200 to the step-down operation (step S20), and the switching circuit 213 additionally switches the connection state to the first state A (step S30). That is, the foregoing case corresponds to the step-down operation state Al .

(0106] Meanwhile, when the target port voltage Vao is lower than the target port voltage Vco, the control switching unit 55 switches the step-up/step-down operation of the primary side full bridge circuit 200 to the step-up operation (step S40), and the switching circuit 213 additionally switches the connection state to the second state B (step S50). That is, the foregoing case corresponds to the step-up operation state B 1.

[0107] An embodiment of the power conversion apparatus and voltage conversion method was described above, but the invention is not limited to the above embodiment, and various amendments and improvements, such as combining or replacing the above embodiment either partially or wholly with another embodiment, may be implemented within the scope of the invention.

[0108] For example, in the above embodiment, a MOSFET, which is a semiconductor element subjected to an ON/OFF operation, was cited as an example of the switching element. However, the switching element may be a voltage control type power element using an insulating gate such as an insulated gate bipolar transistor (IGBT) or a MOSFET, or a bipolar transistor, for example.

[0109] Further, a power supply may be connected to the first input/output port 60a, and a power supply may be connected to the fourth input/output port 60d. Furthermore, a power supply need not be connected to the second input/output port 60c, and a power supply need not be connected to the third input/output port 60b. [0110] Moreover, in FIG. 1 , the primary side low voltage system power supply 62c is connected to the second input/output port 60c, but a power supply need not be connected to either the first input/output port 60a or the second input/output port 60c.

[0111] Moreover, the switching circuit 213 and the control unit 50 may selectively switch between a step-up operation state A2 in which the port voltage Vc is stepped up and output to the first input/output port 60a, and a step-down operation state B2 in which the port voltage Vc is stepped down and output to the first input/output port 60a.

[0112] In the foregoing case, the control unit 50 controls the step-up/step-down performed by the primary side full bridge circuit 200 according to the voltage of the first input/output port 60a that functions as the output port that outputs the voltage after being subject to voltage conversion in the step-up operation state A2. The control unit 50 controls the step-up/step-down performed by the primary side full bridge circuit 200 according to the deviation between the target port voltage Vao of the port voltage Va of the first input/output port 60a and the detection voltage Vad of the port voltage Va acquired by the sensor unit 70.

[0113] Otherwise, the switching circuit 213 and the control unit 50 may also selectively switch between the step-down operation state Al in which the port voltage Va is stepped down and output to the second input/output port 60c, and the step-down operation state A2 in which the port voltage Vc is stepped down and output to the first input/output port 60a.

[0114] In the foregoing case, the control unit 50 controls the step-up/step-down performed by the primary side full bridge circuit 200 according to the voltage of the second input/output port 60c that functions as the output port that outputs the voltage after being subject to voltage conversion in the step-down operation state Al . For example, the control unit 50 operates the primary side full bridge circuit 200 so that the port voltage Va is stepped down according to the deviation between the target port voltage Vco of the port voltage Vc of the second input/output port 60c and the detection voltage Vcd of the port voltage Vc acquired by the sensor unit 70. Meanwhile, the control unit 50 controls the step-up/step-down performed by the primary side full bridge circuit 200 according to the voltage of the first input/output port 60a that functions as the output port that outputs the voltage after being subject to voltage conversion in the step-down operation state B2. For example, the control unit 50 operates the primary side full bridge circuit 200 so that the port voltage Vc is stepped down according to the deviation between the target port voltage Vao of the port voltage Va of the first input/output port 60a and the detection voltage Vad of the port voltage Va acquired by the sensor unit 70.

[0115] Otherwise, the switching circuit 213 and the control unit 50 may also selectively switch between the step-up operation ^'state A2 in which the port voltage Vc is stepped up and output to the first input/output port 60a, and the step-up operation state B 1 in which the port voltage Va is stepped up and output to the second input/output port 60c.

[0116] In the foregoing case, the control unit 50 controls the step-up/step-down performed by the primary side full bridge circuit 200 according to the voltage of the first input/output port 60a that functions as the output port that outputs the voltage after being subject to voltage conversion in the step-up operation state A2. For example, the control unit 50 operates the primary side full bridge circuit 200 so that the port voltage Vc is stepped up according to the deviation between the target port voltage Vao of the port voltage Va of the first input/output port 60a and the detection voltage Vad of the port voltage Va acquired by the sensor unit 70. Meanwhile, the control unit 50 controls the step-up/step-down performed by the primary side full bridge circuit 200 according to the voltage of the second input/output port 60c that functions as the output port that outputs the voltage after being subject to voltage conversion in the step-up operation state B l . For example, the control unit 50 operates the primary side full bridge circuit 200 so that the port voltage Va is stepped up according to the deviation between the target port voltage Vco of the port voltage Vc of the second input/output port 60c and the detection voltage Vcd of the port voltage Vc acquired by the sensor unit 70.

[0117] Moreover, as a result of the secondary side conversion circuit 30 also including a switching unit that is similar to the switching circuit 213, it is possible to alleviate the conditions that restrict the magnitude relation of the voltage of the third input/output port 60b and the voltage of the fourth input/output port 60d. That is, the port voltage Vb may be greater than the port voltage Vd, and the port voltage Vd may be greater than the port voltage Vb. The configuration described above with regard to the primary side conversion circuit 20 can also be applied to the secondary side conversion circuit 30.

Claims

CLAIMS:

1. A power conversion apparatus, comprising:

a primary side circuit; and

a secondary side circuit magnetically coupled to the primary side circuit via a transformer,

wherein one of the primary side circuit and the secondary side circuit includes:

a first port;

a second port;

a first voltage part;

a second voltage part;

a voltage conversion unit that converts a voltage between the first voltage part and the second voltage part; and

a switching unit that switches a connection state of the first port and the second port, and the voltage conversion unit between a first state in which the first port and the first voltage part are connected and the second port and the second voltage part are connected, and a second state in which the first port and the second voltage part are connected and the second port and the first voltage part are connected.

2. The power conversion apparatus according to claim 1 , wherein the switching unit switches the connection state according to a target port voltage in the first port and a target port voltage in the second port.

3. The power conversion apparatus according to claim 2, wherein the switching unit switches the connection state to the first state when the target port voltage in the first port is higher than the target port voltage in the second port, and switches the connection state to the second state when the target port voltage in the first port is lower than the target port voltage in the second port.

4. The power conversion apparatus according to any one of claims 1 to 3, wherein the first state is a state in which a voltage of the first port is stepped down by the voltage conversion unit and output to the second port, and the second state is a state in which a voltage of the first port is stepped up by the voltage conversion unit and output to the second port.

5. The power conversion apparatus according to claim 4, further comprising:

a control unit for controlling step-up/step-down to be performed by the voltage conversion unit, according to the voltage of the second port.

6. The power conversion apparatus according to claim 5, wherein the control unit controls the step-up/step-down to be performed by the voltage conversion unit, according to a deviation between a detection voltage in the second port and a target port voltage in the second port.

7. The power conversion apparatus according to claim 6, wherein the voltage conversion unit includes an upper arm and a lower arm that convert the voltage of the first port, and

wherein the control unit extends an ON time of either the upper arm or the lower arm as the detection voltage is lower relative to the target port voltage in the second port.

8. The power conversion apparatus according to claim 7, wherein the control unit extends an ON time of the upper arm of the upper and lower arms as the detection voltage is lower relative to the target port voltage in the second port when the connection state is the first state, and extends an ON time of the lower arm of the upper and lower arms as the detection voltage is lower relative to the target port voltage in the second port when the connection state is the second state.

9. The power conversion apparatus according to claim 6, wherein the voltage conversion unit includes an upper am and a lower arm that convert the voltage of the first port, and

wherein the control unit switches a target to be controlled according to the deviation from one arm of the upper and lower arms to the other arm.

10. The power conversion apparatus according to claim 9, wherein the target is controlled according to an ON time that is determined according to the deviation.

1 1. The power conversion apparatus according to any one of claims 5 to 10, wherein the control unit switches a step-up/step-down operation of the voltage conversion unit according to a target port voltage in the first port and a target port voltage in the second port.

12. The power conversion apparatus according to claim 1 1 , wherein the control unit switches the step-up/step-down operation to a step-down operation when the target port voltage in the first port is higher than the target port voltage in the second port, and switches the step-up/step-down operation to a step-up operation when the target port voltage in the first port is lower than the target port voltage in the second port.

13. The power conversion apparatus according to any one of claims 1 to 3, wherein the first state is a state in which a voltage of the second port is stepped up by the voltage conversion unit and output to the first port, and the second state is a state in which a voltage of the second port is stepped down by the voltage conversion unit and output to the first port.

14. The power conversion apparatus according to claim 13, further comprising:

a control unit that controls a voltage conversion performed by the voltage conversion unit, according to a voltage of the first port.

15. The power conversion apparatus according to any one of claims 1 to 3, wherein the first state is a state in which a voltage of the first port is stepped down by the voltage conversion unit and output to the second port, and the second state is a state in which a voltage of the second port is stepped down by the voltage conversion unit and output to the first port.

16. The power conversion apparatus according to any one of claims 1 to 3, wherein the first state is a state in which a voltage of the second port is stepped up by the voltage conversion unit and output to the first port, and the second state is a state in which a voltage of the first port is stepped up by the voltage conversion unit and output to the second port.

17. The power conversion apparatus according to claim 15 or 16, further comprising; a control unit that controls a voltage conversion performed by the voltage conversion unit, according to a voltage of the first port and a voltage of the second port.

18. A voltage conversion method of converting a voltage between a first port and a second port with a voltage conversion unit that converts a voltage between a first voltage part and a second voltage part, comprising:

switching a connection state of the first port and the second port, and the voltage conversion unit between a first state in which the first port and the first voltage part are connected and the second port and the second voltage part are connected, and a second state in which the first port and the second voltage part are connected and the second port and the first voltage part are connected.