Power conversion system and method for controlling power conversion device

Abstract

In the present invention, a power conversion device includes a first circuit, a transformer, a second circuit, and a third circuit. The first circuit has a first switch for converting inputted power. The transformer includes a first coil to which power converted by the first circuit is inputted, a second coil for converting and outputting the voltage inputted to the first coil, and a third coil for converting and outputting the voltage inputted to the first coil. The second circuit converts the power outputted from the second coil. The third circuit converts the power outputted from the third coil. The second circuit or the third circuit has a second switch. The control unit: recognizes the state of power inputted to the first circuit, the state of power converted by the second circuit, and the state of power converted by the third circuit; and controls the individual power converted by the second circuit and the third circuit by controlling the first switch and the second switch on the basis of the recognized state of the power.

Description

Control method for power conversion device and power conversion system

[0001] The present invention relates to a control method for a power conversion device and a power conversion system.

[0002] A triple active bridge (TAB) power converter having one input and two outputs is known (see Patent Document 1). The power converter includes a transformer with three windings. First, second, and third bridge circuits are connected to the three windings, respectively, and first, second, and third AC voltages are input and output.

[0003] JP-T-2008-543271A JP-A-2008-109754A

[0004] In Patent Document 1, the first bridge circuit to the third bridge circuit each include a switch to control the phase shift between the phases of the first AC voltage and the second AC voltage and the phase shift between the phases of the first AC voltage and the third AC voltage, respectively, which increases the cost of the switch and its driver circuit.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to reduce the cost of a power conversion device.

[0006] One aspect of the present invention is a method for controlling a power conversion device by a control unit. The power conversion device includes a first circuit, a transformer, a second circuit, and a third circuit. The first circuit has a first switch that converts input power. The transformer has a first coil that receives power converted by the first circuit, a second coil that converts and outputs a voltage input to the first coil, and a third coil that converts and outputs a voltage input to the first coil. The second circuit converts power output from the second coil. The third circuit converts power output from the third coil. One of the second circuit and the third circuit has a second switch. The control unit recognizes the state of power input to the first circuit, the state of power converted by the second circuit, and the state of power converted by the third circuit, and controls the first switch and the second switch based on the recognized states of power, thereby controlling each of the powers converted by the second circuit and the third circuit.

[0007] According to the present invention, the cost of the power conversion device can be reduced.

[0008] FIG. 1 is a block diagram showing a power conversion system 1 including a power conversion device 10 according to a first embodiment, and peripheral devices 2 to 4 connected to the power conversion device 10. FIG. 2 is a circuit diagram showing an example of a detailed circuit configuration of the power conversion device 10 of FIG. 1. FIG. 3 is a timing chart showing an example of a switching pattern of the first switch elements S1 to S4 and the second switch elements Q1 to Q4 of FIG. 2. FIG. 4 is a timing chart showing an example of a switching pattern of the first switch elements S1 to S4 and the third switch elements R1 to R4 of FIG. 2. FIG. 5 is a block diagram showing a power conversion device 10 according to a second embodiment and peripheral devices 2, 3a, and 4 connected to the power conversion device 10. FIG. 6 is a diagram showing a relationship between the phase θ1 of the first switch SS and the power P input to the first circuit 11 in the power conversion device 10 according to the embodiment. １ｉｎ 7 is a graph showing the relationship between the phase difference θ21 between the first switch SS and the second switch QQ and the power value P converted by the second circuit 13 and the third circuit 14, respectively, in the power conversion device 10 according to the embodiment. ２ｏｕｔ , P ３ｏｕｔ8 is a graph showing the relationship between the voltage input to the first coil 121 and the voltage input to the second coil 122. FIG. 8 is a graph showing the time change of the voltage input to the first coil 121 when the phase θ1 is 0°. FIG. 9 is a graph showing the time change of the voltage input to the first coil 121 when the phase θ1 is 90°. FIG. 10 is a graph showing the time change of the voltage input to the first coil 121, the voltage input to the second coil 122, and the voltage input to the third coil 123 when the phase θ1 is 90° and the phase difference θ21 is 45°. FIG. 11 is a block diagram showing a power conversion device 10 and peripheral devices 2, 3a, and 4 connected to the power conversion device 10 according to a third embodiment. FIG. 12 is a block diagram showing a power conversion device 10 and peripheral devices 2, 3a, and 4 connected to the power conversion device 10 according to a fourth embodiment. FIG. 13 is a block diagram showing a power conversion device 10 and peripheral devices 2, 3a, and 4 connected to the power conversion device 10 according to a fifth embodiment. FIG. 14 is a block diagram showing a power conversion device 10 according to a sixth embodiment and peripheral devices 2, 3a, and 4 connected to the power conversion device 10. FIG. 15 is a block diagram showing a power conversion system 1 including a power conversion device 10 according to a seventh embodiment, and peripheral devices 2 to 4 connected to the power conversion device 10. FIG. 16 is a graph showing an example of a control method for the power conversion device 10 according to Example 1 of the seventh embodiment. FIG. 17 is a graph showing another example of a control method for the power conversion device 10 according to Example 2 of the seventh embodiment. FIG. 18 is a graph showing an example of a control method for the power conversion device 10 according to Example 3 of the seventh embodiment, which is a control method for releasing the power limit on the third circuit 14. FIG. 19 is a graph showing another example of a control method for the power conversion device 10 according to Example 3 of the seventh embodiment, which is a control method for releasing the power limit on the third circuit 14. FIG. 20 is a graph showing the frequency characteristics of the output power of a DC-DC converter (second circuit 13) mounted on a vehicle.

[0009] The embodiments will be described with reference to the drawings. In the description of the drawings, the same parts are designated by the same reference numerals and the description thereof will be omitted.

[0010] First Embodiment A power conversion system 1 including a power conversion device 10 according to a first embodiment, and peripheral devices 2 to 4 connected to the power conversion device 10, will be described with reference to FIG. 1 . The power conversion system 1 includes the power conversion device 10 having one input and two outputs, and a control unit 20 that controls the power conversion device 10. The power conversion device 10 includes a first circuit 11, a transformer 12, a second circuit 13, and a third circuit 14. The first circuit 11 includes a first switch SS that converts input power. The transformer 12 includes a first coil 121 to which power converted by the first circuit 11 is input, a second coil 122 that converts and outputs the voltage input to the first coil 121, and a third coil 123 that converts and outputs the voltage input to the first coil 121. The second circuit 13 converts the power output from the second coil 122. The third circuit 14 converts the power output from the third coil 123. One of the second circuit 13 and the third circuit 14 has a second switch QQ. In the example shown in Figure 1, the second circuit 13 has the second switch QQ, but the third circuit 14 may also have the second switch QQ.

[0011] The control unit 20 recognizes the state of power input to the first circuit 11, the state of power converted by the second circuit 13, and the state of power converted by the third circuit 14, and controls the first switch SS and the second switch QQ based on the recognized three power states, thereby controlling the power converted by the second circuit 13 and the third circuit 14. Therefore, the other of the second circuit 13 and the third circuit 14, that is, in the example of FIG. 2 , the third circuit 14 does not need to be controlled, and a switch is not required in the third circuit 14. Therefore, compared to when each of the first to third circuits 11, 13, and 14 includes a switch, the costs of the switches and their driver circuits are reduced, and the cost of the entire power conversion device 10 is also reduced.

[0012] The recognized three power states may be referred to as "input / output power information 30." The states of the power input to the first circuit 11 include the power P １ｉｎ , the current, voltage, and power output from the first circuit 11. The state of the power converted by the second circuit 13 includes the power value P ２ｉｎ, the current, voltage, and power converted and output by the second circuit 13. The state of the power converted by the third circuit 14 includes the power value P ３ｉｎ , and the current, voltage, and power converted and output by the third circuit 14.

[0013] In the first embodiment, the first circuit 11 converts the DC power output from the DC voltage source 2 into AC power and outputs it to the first coil 121. The transformer 12 converts the input voltage to the first coil 121 into an output voltage of the second coil 122 according to the winding ratio of the first coil 121 and the second coil 122. The transformer 12 converts the input voltage to the first coil 121 into an output voltage of the third coil 123 according to the winding ratio of the first coil 121 and the third coil 123. The second circuit 13 converts the AC power output from the second coil 122 into DC power and outputs it to the first load 3. The third circuit 14 converts the AC power output from the third coil 123 into DC power and outputs it to the second load 4.

[0014] The first circuit 11 converts DC power into AC power by operating a first switch. One of the second circuit 13 and the third circuit 14, each having a second switch, converts AC power into DC power by operating the second switch. The first circuit 11 and one of the second circuit 13 and the third circuit 14, each having a second switch, may have any circuit configuration as long as it is a switch-type power conversion circuit. The other of the second circuit 13 and the third circuit 14 may be a rectifier circuit using a diode or the like.

[0015] The control unit 20 can be realized using a microcomputer equipped with a CPU (Central Processing Unit), memory, and input / output units. A computer program (control program) for causing the microcomputer to function as the control unit 20 is installed in the microcomputer and executed. As a result, the microcomputer functions as multiple information processing units included in the control unit 20. Note that while an example in which the control unit 20 is realized by software is shown here, it is of course also possible to configure the control unit 20 by providing dedicated hardware for executing each piece of information processing. The control unit 20 may also serve as an electronic control unit (ECU) used for other vehicle-related control.

[0016] An example of a detailed circuit configuration of the power conversion device 10 of FIG. 1 will be described with reference to FIG. 2 . In FIG. 2 , one of the second circuit 13 and the third circuit 14, each having a second switch QQ, is the second circuit 13. The first circuit 11 has first switch elements S1 to S4 as the first switch SS, and the second circuit 13 has second switch elements Q1 to S4 as the second switch QQ. Furthermore, the other of the second circuit 13 and the third circuit 14, i.e., the third circuit 14 of FIG. 2, also has third switch elements R1 to R4. That is, both the second circuit 13 and the third circuit 14 have switches, and AC power is converted to DC power by operating the switches. The first coil 121, the second coil 122, and the third coil 123 are magnetically coupled by a core (iron core) 124.

[0017] Each of the first circuit 11, the second circuit 13, and the third circuit 14 has an H-bridge circuit with four switch elements. That is, a first leg and a second leg are connected in parallel between a high-voltage line and a low-voltage line. The switch elements constituting the H-bridge circuit can be composed of semiconductor devices including, for example, an IGBT (insulated gate bipolar transistor) and a MOSFET (metal-oxide semiconductor field-effect transistor). By applying an on signal or an off signal to the gate electrode of the MOSFET, the conductive state (on) and the cut-off state (off) of the switch can be controlled.

[0018] First switch elements S1 and S2 are connected in series on a first leg of the first circuit 11, and first switch elements S3 and S4 are connected in series on a second leg of the first circuit 11. One terminal of the first coil 121 is connected between the first switch elements S1 and S2, and the other terminal of the first coil 121 is connected between the first switch elements S3 and S4. The first circuit 11 may include a smoothing capacitor 111 connected in parallel to the first leg and the second leg.

[0019] Second switch elements Q1 and Q2 are connected in series on a first leg of the second circuit 13, and second switch elements Q3 and Q4 are connected in series on a second leg of the second circuit 13. One terminal of the second coil 122 is connected between the second switch elements Q1 and Q2, and the other terminal of the second coil 122 is connected between the second switch elements Q3 and Q4. The second circuit 13 may include a smoothing capacitor 131 connected in parallel to the first leg and the second leg.

[0020] Fourth switch elements R1 and R2 are connected in series on a first leg of the third circuit 14, and third switch elements R3 and R4 are connected in series on a second leg of the third circuit 14. One terminal of the third coil 123 is connected between the third switch elements R1 and R2, and the other terminal of the third coil 123 is connected between the third switch elements R3 and R4. The third circuit 14 may include an LC filter 143 consisting of an inductance 1431 and a capacitor 1432, connected between the third switch elements R1 to R4 and the second load 4.

[0021] FIG. 2 illustrates an example of the first load 3 in FIG. 1 as an auxiliary device mounted on an electric vehicle (hereinafter referred to as an "on-board auxiliary device 3a"). When the first load 3 is the on-board auxiliary device 3a, the power conversion device 10 or the power conversion system 1 is mounted on the electric vehicle, and the DC voltage source can serve as a drive power source for driving the electric vehicle. For example, the control unit 20 can be located outside the electric vehicle by performing road-to-road communication with the power conversion device 10. The control unit 20 may be mounted on the electric vehicle and communicate with the power conversion device 10 via a wire such as a Controller Area Network (CAN) wiring. The on-board auxiliary device 3a includes a navigation system, power windows, brakes, wipers, headlights, and door locks. Instead of the on-board auxiliary device 3a, the first load 3 may be an auxiliary device battery (12V battery) for supplying power to the on-board auxiliary device 3a. When the frequency of use of the vehicle auxiliary equipment 3a to which the power converted by the second circuit 13 is input is higher than the frequency of use of the second load 4, the second circuit 13 having the second switch QQ can improve the conversion efficiency of the entire power converted by the second circuit 13 and the third circuit 14.

[0022] 3, an example of a switching pattern of the first switch elements S1 to S4 and the second switch elements Q1 to Q4 in FIG. 2 will be described. The switching pattern is a waveform that is generated by a driver circuit (not shown) to turn on / off each switch and input to the gate electrode of the MOSFET. The switching pattern is controlled by the control unit 20.

[0023] The first switch elements S1 and S2 on the first leg alternately turn on and off. When the first switch element S1 is on, the first switch element S2 is off, and when the first switch element S1 is off, the first switch element S2 is on. Similarly, the first switch elements S3 and S4 on the second leg alternately turn on and off. All of the first switch elements S1 to S4 alternately turn on and off in the same cycle, and the proportion of times they are on in one cycle, i.e., the duty ratio, is 50%.

[0024] Similarly, the second switch elements Q1 and Q2 on the first leg alternately turn on and off. When the second switch element Q1 is on, the second switch element Q2 is off, and when the second switch element Q1 is off, the second switch element Q2 is on. Similarly, the second switch elements Q3 and Q4 on the second leg alternately turn on and off. All of the second switch elements Q1 to Q4 alternately turn on and off in the same cycle, and the proportion of on-states in one cycle, i.e., the duty ratio, is 50%. The cycles of the second switch elements Q1 to Q4 are the same as the cycles of the first switch elements S1 to S4.

[0025] The control unit 20 in Fig. 1 controls the phase θ1 of the first switch SS and the phase difference θ21 between the first switch SS and the second switch QQ. As shown in Fig. 3 , the "phase θ1 of the first switch SS" is the phase difference between the on / off switching phase of the first switch elements S1 and S2 on the first leg and the on / off switching phase of the first switch elements S3 and S4 on the second leg. That is, the "phase θ1 of the first switch SS" is the phase difference between the first leg and the second leg of the first circuit 11. Note that Fig. 3 shows the phase difference between the rising edge (off to on) of the first switch element S4 and the falling edge (on to off) of the first switch element S3 relative to the rising edge (off to on) of the first switch element S1 and the falling edge (on to off) of the first switch element S2 as "phase θ1." Not limited to this, the phase difference between the phase of the falling edge (on → off) of the first switch element S4 and the phase of the rising edge (off → on) of the first switch element S3 relative to the phase of the falling edge (on → off) of the first switch element S1 and the phase of the rising edge (off → on) of the first switch element S2 is also the same "phase θ1."

[0026] On the other hand, the "phase difference θ21 between the first switch SS and the second switch QQ" is the phase difference between the phase of on / off switching of the first switch element S1 and the phase of on / off switching of the second switch element Q1. Since the first switches S1 to S4 and the second switches Q1 to Q4 have the same cycle and duty ratio, the phase difference between the phase of on / off switching of the first switch elements S2 to S4 and the phase of on / off switching of the second switch elements Q2 to Q4 is also the same "phase difference θ21."

[0027] As shown in FIG. 3, the control unit 20 in FIG. 1 can control the power converted by the second circuit 13 and the third circuit 14 to desired values ​​by controlling the phase θ1 of the first switch SS and the phase difference θ21 between the first switch SS and the second switch QQ.

[0028] 4, an example of a switching pattern of the first switch elements S1 to S4 and the third switch elements R1 to R4 in FIG. 2 will be described. The switching pattern is a waveform that is generated by a driver circuit (not shown) to turn on / off each switch and input to the gate electrode of the MOSFET. The switching pattern is controlled by the control unit 20.

[0029] The switching patterns and phase θ1 of the first switch elements S1 to S4 are the same as those in FIG. 3, and will not be described again.

[0030] The control unit 20 can control the third switch elements R1 to R4 using a synchronous rectification control method based on duty ratio control. Specifically, the third switch elements R1 and R4 are controlled to be on when the first switch element S1 or S4 is on, and are controlled to be off when the first switch elements S1 and S4 are off. Similarly, the third switch elements R2 and R3 are controlled to be on when the first switch element S2 or S3 is on, and are controlled to be off when the first switch elements S1 and S4 are off. Note that the control method for the third switch elements R1 to R4 is not limited to the example shown in FIG. 4 , and any other synchronous control method may be used. While FIG. 4 shows the duty ratio D1 of the third switch element R1, the duty ratios D1 of the other third switch elements R2 to R4 are the same. Using the third switch RR as the third circuit 14 can reduce normal losses compared to using a diode. 4, the control unit 20 can improve the conversion efficiency of each power converted by the third circuit 14 by controlling the duty ratio D1 of the third switch elements R1 to R4. By controlling the duty ratio of the third switches (third switch elements R1 to R4) synchronized with the duty ratio (duty ratio) of the first circuit 11, it is possible to achieve synchronous rectification of the third circuit 14 and control each power converted by the second circuit 13 and the third circuit 14 to a desired value.

[0031] In the first embodiment, the second circuit 13 includes the second switch QQ. However, the present invention is not limited to this, and the third circuit 14 may include a "second switch." That is, the control unit 20 may control the power converted by the second circuit 13 and the third circuit 14 to desired values ​​by controlling the phase θ1 of the first switch SS and the phase difference θ31 between the first switch SS and the third switch QQ. In this case, the control unit 20 may control the duty ratios of the second switch elements Q1 to Q4 instead of the third switch elements R1 to R4 in FIG. 4 .

[0032] Second Embodiment A power conversion device 10 according to a second embodiment and peripheral devices 2, 3a, and 4 connected to the power conversion device 10 will be described with reference to FIG. 5. FIG. 5 corresponds to another example of the detailed circuit configuration of the power conversion device 10 of FIG. 1. The example shown in FIG. 5 differs from the example of FIG. 2 in that the third circuit 14 has a diode instead of a switch. The other configuration of FIG. 5 is the same as that of FIG. 2, and therefore will not be described again. The third circuit 14 has a rectifier circuit 142 using four diodes U1 to U4.

[0033] The rectifier circuit 142 forms a full-wave rectifier circuit (diode bridge circuit) having four diodes U1 to U4. Two diodes U1 and U2 connected in series and two diodes U3 and U4 connected in series are connected between the high-voltage line and low-voltage line of the third circuit 14. One terminal of the third coil 123 is connected to the anode of diode U1 and the cathode of diode U2, and the other terminal of the third coil 123 is connected to the anode of diode U3 and the cathode of diode U4.

[0034] In the example shown in FIG. 5 , similarly to FIG. 3 , the control unit 20 controls the phase θ1 of the first switch SS and the phase difference θ21 between the first switch SS and the second switch QQ, thereby controlling the power converted by the second circuit 13 and the third circuit 14 to desired values.

[0035] As shown in FIG. 6, in the power conversion device 10 according to the embodiment, the larger the phase θ1 of the first switch SS, the larger the power P １ｉｎ The control unit 20 reduces the phase θ1, thereby reducing the power P １ｉｎ By increasing the phase θ1, the power P input to the first circuit 11 １ｉｎ The power P input to the first circuit 11 is reduced. １ｉｎ The phase θ1 can be varied in the range of 0° to 180°, but the power P １ｉｎ The range in which varies may vary depending on the circuit constants of the power conversion device 10 and the specifications of the DC voltage source 2.

[0036] As shown in FIG. 7, in the power conversion device 10 according to the embodiment, the power values ​​P ２ｏｕｔ , P ３ｏｕｔ The power value P ２ｏｕｔ When the phase difference θ21 is in the range of 0° to 90°, the larger the phase difference θ21 is, and when the phase difference θ21 is in the range of 90° to 180°, the larger the phase difference θ21 is, the smaller the power value P ２ｏｕｔ becomes smaller as the phase difference θ21 increases within the range of 0° to 180°. By reducing the phase difference θ21, the control unit 20 reduces the power converted by the second circuit 13 (one of the second circuit 13 and the third circuit 14) and increases the power converted by the third circuit 14 (the other of the second circuit 13 and the third circuit 14). By increasing the phase difference θ21, the control unit 20 increases the power converted by the second circuit 13 (one of the second circuit 13 and the third circuit 14) and decreases the power converted by the third circuit 14 (the other of the second circuit 13 and the third circuit 14). The power P converted by the second circuit 13 ２ｏｕｔ and the power value P ３ｏｕｔ Both of these can be controlled to desired values.

[0037] The control unit 20 controls the phase θ1 and the phase difference θ21 within the range of 0° to 180°. This allows the power converted by the second circuit 13 and the third circuit 14 to be controlled to a desired value. The control unit 20 may also control the phase difference θ21 within the range of 0° to 90°. When the phase difference θ21 is within the range of 0° to 90°, the power value P ２ｏｕｔ and the power value P ３ｏｕｔ The increase and decrease directions of the power P are opposite to each other. Therefore, the control unit 20 can allocate the output power between the second circuit 13 and the third circuit 14 by using the phase difference θ21. Specifically, by reducing the phase difference θ21, the control unit 20 can reduce the power value P converted by one of the second circuit 13 and the third circuit 14, i.e., the second circuit 13 having the second switch Q. ２ｏｕｔ, and the other of the second circuit 13 and the third circuit 14, that is, the third circuit 14 without the second switch Q, converts the power value P ３ｏｕｔ Furthermore, the control unit 20 can increase the power value P ２ｏｕｔ is increased, and the power value P ３ｏｕｔ By controlling the phase difference θ21 within the range of 0° to 90°, the control unit 20 can reduce the processing load on the DSP (digital signal processing) and the like.

[0038] As described above, according to the second embodiment, the cost of the switch of the third circuit 14 and its driver circuit can be reduced, and the power value P ２ｏｕｔ and the power value P ３ｏｕｔ Both of these can be controlled to desired values.

[0039] 8 is a graph showing the time change of the voltage input to the first coil 121 when the phase θ1 is 0°. FIG. 9 is a graph showing the time change of the voltage input to the first coil 121 when the phase θ1 is 90°. The shaded areas CP in FIGS. 8 and 9 １ The area of ​​the power input to the transformer 12 and the power P １ｉｎ Therefore, when θ1 = 0°, the power P １ｉｎ is the largest, and when θ1=180°, the power P １ｉｎ The control unit 20 can increase the power input to the first circuit 11 by decreasing the phase θ1, and can decrease the power input to the first circuit by increasing the phase θ1.

[0040] 10 shows the time variations of the voltage input to the first coil 121, the voltage input to the second coil 122, and the voltage input to the third coil 123 when the phase θ1 is 90° and the phase difference θ21 is 45°. ２The area of ​​each power output from the second coil 122 and the power value P converted by the second circuit 13 in the half cycle of the switching pattern shown in FIG. ２ｏｕｔ The hatched areas CP in FIG. ３ The area of ​​each power output from the third coil 123 and the power value P converted by the third circuit 14 in the half cycle of the switching pattern shown in FIG. ３ｏｕｔ The directions of the voltages applied to the second coil 122 and the third coil 123 are different. Therefore, the control unit 20 can control the power output by the second circuit 13 and the third circuit 14, as shown in FIG. 7 .

[0041] Third Embodiment A power conversion device 10 according to a third embodiment and peripheral devices 2, 3a, and 4 connected to the power conversion device 10 will be described with reference to Fig. 11. Fig. 11 corresponds to another example of the detailed circuit configuration of the power conversion device 10 of Fig. 1. The example shown in Fig. 11 differs from the example of Fig. 5 in that the third circuit 14 includes a DC / AC inverter 144 to which a DC voltage converted by a rectifier circuit 142 is input.

[0042] The DC-AC inverter 144 has an H-bridge circuit including four switch elements Y1 to Y4. That is, a first leg and a second leg are connected in parallel between a high-voltage line and a low-voltage line. The switch elements Y1 to Y4 that make up the H-bridge circuit can be configured with semiconductor devices including, for example, IGBTs and MOSFETs. The DC-AC inverter 144 converts DC voltage to AC voltage and outputs it to the outlet 146. The DC-AC inverter 144 converts it to, for example, a commercial power supply voltage (100 V AC) used in Japan and outputs it. The control unit 20 controls the power converted by the DC-AC inverter 144 by controlling the on / off of the switch elements Y1 to Y4.

[0043] By installing the power conversion device 10 in an electric vehicle and providing an outlet 146 inside the vehicle cabin, the second circuit 13 can supply power to the onboard auxiliary device 3a while also supplying power to electrical appliances inside and outside the vehicle. The DCDC converter for the onboard auxiliary device 3a and the DC / AC inverter for the outlet 146, which were previously installed separately in the electric vehicle, can be integrated. In other words, by integrating the input side circuit (first circuit 11) and the transformer 12, the power output from the two output side circuits (second circuit 13, third circuit 14) can be individually controlled.

[0044] 11, the third circuit 14 may include a smoothing capacitor 141 connected to the output side of the second switching elements Q1 to Q4 and to the input side of the DC-AC inverter 144. The third circuit 14 may include a second smoothing circuit 145 including an inductance 1451 and a capacitor 1452 on the output side of the DC-AC inverter 144. The other configurations are the same as those in FIG. 5, and therefore will not be described again.

[0045] Fourth Embodiment A power conversion device 10 according to a fourth embodiment and peripheral devices 2, 3a, and 4 connected to the power conversion device 10 will be described with reference to FIG. 12 . FIG. 12 corresponds to another example of the detailed circuit configuration of the power conversion device 10 of FIG. 1 . The example shown in FIG. 12 differs from the example of FIG. 5 in the following respects. The third circuit 14 includes third switches Q1 to Q4. The second circuit 13 includes a rectifier circuit 132 including diodes U1 to U4. The second circuit 13 includes an LC filter 134 including an inductance 1341 and a capacitor 1342 on the output side of the rectifier circuit 132. FIG. 12 illustrates a power conversion device 10 in which one of the second circuit 13 and the third circuit 14 including the second switch QQ of FIG. 1 is the "third circuit 14."

[0046] 3, the control unit 20 controls the phase θ1 of the first switch SS and the phase difference θ31 between the first switches S1 to S4 included in the first circuit 11 and the third switches Q1 to Q4 included in the third circuit 14. The "phase difference θ31" indicates the phase difference between the first circuit 11 and the third circuit 14. The other configurations and operations are the same as those in FIG. 5, and therefore will not be described again.

[0047] Fifth Embodiment A power conversion device 10 and peripheral devices 2, 3a, and 4 connected to the power conversion device 10 according to a fifth embodiment will be described with reference to FIG. 13 . FIG. 13 corresponds to another example of the detailed circuit configuration of the power conversion device 10 of FIG. 1 . The example shown in FIG. 13 differs from the example shown in FIG. 12 in that the second circuit 13 includes a center-tap rectifier circuit 133 using two diodes. The center-tap rectifier circuit 133 forms a full-wave rectifier circuit similar to a bridge type, but allows for a reduction in the number of diodes. The second circuit 13 may include a third smoothing circuit 134, consisting of an inductance 1341 and a capacitor 1342, on the output side of the rectifier circuit 133. The other configurations are the same as those shown in FIG. 12 , and therefore will not be described again.

[0048] Sixth Embodiment A power conversion device 10 according to a sixth embodiment and peripheral devices 2, 3a, and 4 connected to the power conversion device 10 will be described with reference to FIG. 14 . FIG. 14 corresponds to another example of the detailed circuit configuration of the power conversion device 10 of FIG. 1 . The example shown in FIG. 14 differs from the example of FIG. 11 in that the third circuit 14 includes third switches Q1 to Q4, the second circuit 13 includes a rectifier circuit including diodes U1 to U4, and the second circuit 13 includes an LC filter 134 including an inductance 1341 and a capacitor 1342 instead of the smoothing capacitor 131. FIG. 14 illustrates a power conversion device 10 in which one of the second circuit 13 and the third circuit 14 including the second switch QQ of FIG. 1 is the "third circuit 14."

[0049] 3, the control unit 20 controls the phase θ1 of the first switch SS and the phase difference θ31 between the first switches S1 to S4 included in the first circuit 11 and the third switches Q1 to Q4 included in the third circuit 14. The "phase difference θ31" indicates the phase difference between the first switches S1 to S4 of the first circuit 11 and the third switches Q1 to Q4 of the third circuit 14. The other configurations and operations are the same as those in FIG. 11, and therefore will not be described again.

[0050] In the first to sixth embodiments, the first coil 121, the second coil 122, and the third coil 123 are magnetically coupled by a single core (iron core) 124. That is, an integrated transformer using a single core 124 is described. However, the transformer 12 is not limited to this, and may include a first core and a second core that are not magnetically coupled. In this case, it is sufficient that the first coil 121 and the second coil 122 are magnetically coupled by the first core, and the first coil 121 and the third coil 123 are magnetically coupled by the second core. For example, two transformers each having one input and one output may be prepared, and the input coils may be connected in series to integrate the input sides.

[0051] Seventh Embodiment A power conversion system 1 including a power conversion device 10 according to a seventh embodiment, and peripheral devices 2 to 4 connected to the power conversion device 10, will be described with reference to FIG. 15 . The example shown in FIG. 15 differs from the example shown in FIG. 1 in that the third circuit 14 includes a main circuit 142 that converts the power output from the third coil 123 and a DC / AC inverter 144 to which the power converted by the main circuit 142 is input, and the DC / AC inverter 144 includes a second switch YY. The other configurations are the same as those shown in FIG. 1 , and a repeated description will be omitted. That is, the "one of the second circuit 13 and the third circuit 14" that includes the second switch YY is the third circuit 14. The second switch YY shown in FIG. 15 includes, for example, four switch elements Y1 to Y4 that form an H-bridge circuit, as shown in FIGS. 11 and 14 .

[0052] In the seventh embodiment, when the sum of the power value input to the second circuit 13 and the power value input to the third circuit 14 is equal to or greater than a first specified value, the control unit 20 limits the power input to the third circuit 14. The maximum allowable power value of the transformer 12 is a value smaller than the sum of the maximum allowable power value of the second circuit 13 and the maximum allowable power value of the third circuit 14.

[0053] When the sum of the power value input to the second circuit 13 and the power value input to the third circuit 14 is equal to or greater than a first specified value, the power converted by the third circuit 14 is limited. This makes it possible to prevent power exceeding the maximum allowable power value from being input to the transformer 12, even if the maximum allowable power value of the transformer 12 is kept to a value equal to or less than the sum of the maximum allowable power value of the second circuit 13 and the maximum allowable power value of the third circuit 14. Even if the transformer 12 does not guarantee the sum of the maximum allowable power values ​​of the second circuit 13 and the third circuit 14, it is possible to prevent power input exceeding the maximum allowable power value of the transformer 12, thereby enabling the transformer 12 to be made smaller.

[0054] Patent Document 2 (JP 2008-109754 A) discloses a switching power supply device that reduces the installation space of the entire power supply device by integrating a DC / DC converter and a DC / AC inverter mounted on an electric vehicle. However, the maximum allowable power of the transformer in the integrated circuit is the sum of the maximum power values ​​of the transformers in both circuits before integration, resulting in an increase in the transformer size, and therefore the miniaturization effect of circuit integration is small. According to the seventh embodiment, it is possible to reduce the size of the transformer 12 while satisfying the power requirements of the first load 3 and the second load 4 as much as possible.

[0055] When the power conversion device 10 is mounted on a vehicle and supplies power to the on-board auxiliary equipment 3a as the first load 3, even if the maximum allowable power value of the transformer 12 is set low as described above, the frequency with which the second circuit 13, which supplies power to the on-board auxiliary equipment 3a, operates at maximum power is extremely low (see Figure 20). Figure 20 is a graph showing the frequency characteristics of the output power of the DCDC converter (second circuit 13) mounted on a vehicle. The horizontal axis represents the relative value (%) with respect to the maximum allowable power value of the second circuit 13. It can be seen that the second circuit 13 operates frequently under light loads relative to its maximum allowable power value and outputs maximum power extremely rarely. Due to this characteristic, even if the maximum allowable power value of the transformer 12 is set low, in many cases the transformer 12 has a large power margin, so it is not necessary to limit the power supply to the second load 4. In other words, due to this frequency characteristic unique to on-board operation, the DC-AC inverter 144 of the third circuit 14 can be used at its maximum allowable power value in many situations. The frequency with which the power input to the third circuit 14 is limited is low. In addition, the cases in which the DCDC converter (second circuit 13) operates at near maximum power are when a large number of vehicle accessories 3a are used simultaneously and emergency situations such as sudden braking or sudden steering are required, and in such situations there is little disadvantage to the user due to the restriction of power supply to the second load 4 such as an electrical appliance.

[0056] The first specified value may be the maximum allowable power value of the transformer 12. This makes it possible to prevent power exceeding the maximum allowable power value from being input to the transformer.

[0057] Although specific circuit configuration examples according to the seventh embodiment are not shown, for example, the circuit configurations shown in FIGS. 11 and 14 may be applied. Furthermore, some circuit configurations shown in FIGS. 11 and 14 may be modified based on FIGS. 2, 5, 12, and 13. For example, the center-tap rectifier circuit 133 shown in FIG. 13 may be applied as the main circuit 142 instead of the bridge-type rectifier circuit shown in FIG. 11. Both the main circuits of the second circuit 13 and the third circuit 14 shown in FIG. 15 may be rectifier circuits without switches. This is because the control unit 20 can control the power converted by the third circuit 14 by controlling the switch of the DC-AC inverter 144 included in the third circuit 14. The control unit 20 can control the power converted by the second circuit 13 and the third circuit 14 by controlling the phase θ1 of the first switch SS included in the first circuit 11 and the phase difference θ31 between the first switch SS and the second switch QQ included in the DC-AC inverter 144.

[0058] Examples 1 to 4 of the control method for the power conversion device 10 according to the seventh embodiment will be described with reference to the graphs of Figures 16 to 19. The graphs of Figures 16 and 17 show the power value P ２ｉｎ and the power value P input to the third circuit 14 ３ｉｎ The time change of "P" in Figs. ｔｒ＿ｍａｘ " indicates the maximum allowable power value of the transformer 12, and "P ３ｉｎ＿ｍａｘ " indicates the maximum allowable power value of the third circuit 14. The power value P ３ｉｎ is the maximum allowable power value P of the third circuit 14. ３ｉｎ＿ｍａｘ That is, the third circuit 14 is set to the maximum allowable power value P ３ｉｎ＿ｍａｘ At this time, if the power consumption of the first load 3 such as the on-board auxiliary device 3a increases, the power value P ２ｉｎ The control unit 20 increases the power value P ２ｉｎ and power value P ３ｉｎ The sum of these values ​​is a first specified value, for example, the maximum allowable power value P ｔｒ＿ｍａｘSpecifically, the control unit 20 controls the switches Y1 to Y4 of the DC-AC inverter 144 to limit the power converted by the DC-AC inverter 144. As a result, the power value P ２ｉｎ The total value of the power converted by the DC / AC inverter 144 is the maximum allowable power value P ｔｒ＿ｍａｘ It is possible to control it so that it does not exceed the

[0059] In the example of the control method shown in FIG. 16, the power value P ３ｉｎ This allows the maximum allowable power value P ３ｉｎ＿ｍａｘ This is an effective method when the power consumption of the second load 4 can be continuously adjusted.

[0060] (Example 2) On the other hand, when the power consumption of the second load 4 cannot be continuously adjusted, as shown in another example of the control method of FIG. 17, the power value P ３ｉｎ to zero, cutting off the power supply to the second load 4. This is an effective method because many electrical appliances cannot continuously adjust their power consumption.

[0061] The control unit 20 controls the switches Y1 to Y4 of the DC / AC inverter 144 to set the power value P ２ｉｎ Instead of lowering the power, if the power is converted using the switches Q1 to Q4 provided in the main circuit 142 of the second circuit 13 or the third circuit 14, the power value P can be reduced by controlling the phase difference θ21 or θ31 between the phase of these switches and the phase of the switch of the first circuit 11. ２ｉｎ As a result, the power value P ２ｉｎ and power value P ３ｉｎ The total value of the above can be reduced.

[0062] Power value P ２ｉｎ and power value P ３ｉｎ For example, the input power to the first circuit 11 is calculated as a power value P ２ｉｎ and power value P ３ｉｎAlternatively, the power value P ２ｉｎ and power value P ３ｉｎ Alternatively, each of these may be directly detected and added together.

[0063] (Example 3) Next, a control method for releasing the power limit on the third circuit 14 will be described with reference to Fig. 18 and Fig. 19. Fig. 18 is a graph showing an example of a control method for releasing the power limit on the third circuit 14.

[0064] The control unit 20 controls the power value P ３ｉｎ When the power value P ２ｉｎ is the second specified value Th ２ If t １ , the power value P input to the third circuit 14 ３ｉｎ In the example shown in FIG. ３ｉｎ 17, is limited to zero. In other words, the power supply to the second load 4 is cut off. At this time, if the power consumed by the first load 3 such as the on-board auxiliary device 3a decreases, the power value P ２ｉｎ The power value P ２ｉｎ is a predetermined second specified value Th ２ If t １ Then, the control unit 20 calculates the power value P ３ｉｎ The power value P ３ｉｎ＿Ｈ indicates the case where the power consumption of the second load 4 is large, and the power value P ３ｉｎ＿Ｌ indicates the case where the power consumption of the second load 4 is small.

[0065] The power value P input to the second circuit 13 ２ｉｎ Even if the limit on the power input to the third circuit 14 is released in a state where the input power value P ２ｉｎ and the input power value P of the third circuit 14 ３ｉｎ The total value of the input power P ３ｉｎTherefore, the power value P ２ｉｎ is the second specified value Th ２ If t １ , the power value P input to the third circuit 14 ３ｉｎ As a result, the input power value P ３ｉｎ This can prevent the signal from becoming oscillatory.

[0066] In the third embodiment, the second specified value Th ２ is the maximum allowable power value P of the first circuit 11 １ｉｎ＿ｍａｘ The maximum allowable power value P of the third circuit 14 is calculated from ３ｉｎ＿ｍａｘ As a result, even if the output restriction to any second load 4 is released, the input power value P ３ｉｎ The maximum allowable power value P of the third circuit 14 can be prevented from becoming oscillatory. ３ｉｎ＿ｍａｘ By adopting this method, it is effective for the second load 4 whose power consumption cannot be continuously adjusted. It is possible to prevent power input to the transformer 12 from exceeding the maximum allowable power value.

[0067] In the third embodiment, the second specified value Th ２ is the maximum allowable power value P of the first circuit 11 １ｉｎ＿ｍａｘ The power value P input to the third circuit 14 immediately before the power restriction to the third circuit 14 is started is calculated from the power value P ３ｉｎ＿ｍ This is an effective method for the second load 4 whose power consumption cannot be continuously adjusted. ３ｉｎ＿ｍ The smaller the second specified value Th ２ Since the input power value P ２ｉｎ A slight decrease in the power value P ３ｉｎ The limit on the input power value P ２ｉｎ The power supply to the second load 4 can be resumed even if the power value P input to the third circuit 14 immediately before the power limit to the third circuit 14 is started. ３ｉｎ＿ｍ This is an effective method when the following can be recorded:

[0068] (Example 4) The control unit 20 controls the power value P ３ｉｎ When the third circuit 14 is instructed to supply power and the power value P ２ｉｎ is the second specified value Th ２ When the power value P ３ｉｎ This can prevent the power supply to the second load 4 from being restricted immediately after the second load 4 is started, not only when the power supply to the second load 4 is restricted, but also when the second load 4 is started for the first time. Here, when the second load 4 is started for the first time, it is difficult to predict the power consumption of the second load 4. Therefore, the second specified value Th ２ is the maximum allowable power value P of the first circuit 11 １ｉｎ＿ｍａｘ The maximum allowable power value P of the third circuit 14 is calculated from ３ｉｎ＿ｍａｘ This makes it possible to accommodate the second load 4 with any power consumption.

[0069] Although the embodiments of the present invention have been described above, the descriptions and drawings that form part of this disclosure should not be understood to limit the present invention. Various alternative embodiments, examples, and operating techniques will become apparent to those skilled in the art from this disclosure.

[0070] REFERENCE SIGNS LIST 1 Power conversion system 3a Vehicle accessory 10 Power conversion device 11 First circuit 12 Transformer 13 Second circuit 14 Third circuit 20 Control unit 121 First coil 122 Second coil 123 Third coil 142 Rectifier circuit (main circuit) 144 DC / AC inverter D1, D2 Duty ratio P ｔｒ＿ｍａｘ Maximum allowable power value of the transformer P １ｉｎ＿ｍａｘ Maximum allowable power value of the first circuit P2in ＿ｍａｘ Maximum allowable power value of the second circuit P ３ｉｎ＿ｍａｘ Maximum allowable power value of the third circuit QQ Second switch R1 to R4 Third switch SS First switch Th ２ Second specified value θ1 Phase θ21, θ31 Phase difference

Claims

1. A method for controlling a power conversion device by a control unit, The power conversion device is a first circuit having a first switch for converting input power; a transformer having a first coil to which the power converted by the first circuit is input, a second coil that converts the voltage input to the first coil and outputs the converted voltage, and a third coil that converts the voltage input to the first coil and outputs the converted voltage; a second circuit that converts the power output from the second coil; a third circuit that converts the power output from the third coil, one of the second circuit and the third circuit includes a second switch; The control unit Recognizing a state of power input to the first circuit, a state of power converted by the second circuit, and a state of power converted by the third circuit; controlling the first switch and the second switch based on the recognized state of the power, thereby controlling the powers converted by the second circuit and the third circuit; A method for controlling a power conversion device.

2. The method for controlling a power conversion device according to claim 1, the control unit controls each of the powers converted by the second circuit and the third circuit by controlling a phase of the first switch and a phase difference between the first switch and the second switch. A method for controlling a power conversion device.

3. 3. The method for controlling a power conversion device according to claim 1 or 2, the other of the second circuit and the third circuit has a third switch that converts input power. A method for controlling a power conversion device.

4. The method for controlling a power conversion device according to claim 3, the control unit controls each of the powers converted by the second circuit and the third circuit by controlling a phase of the first switch, a phase difference between the first switch and the second switch, and a duty ratio of the third switch synchronized with a duty ratio of the first switch. A method for controlling a power conversion device.

5. 3. The method for controlling a power conversion device according to claim 1 or 2, the other of the second circuit and the third circuit includes a rectifier circuit that converts input power. A method for controlling a power conversion device.

6. 6. The method for controlling a power conversion device according to claim 5, The electric power converted by the second circuit is input to an on-board auxiliary device provided in a vehicle equipped with the power conversion device. A method for controlling a power conversion device.

7. 7. The method for controlling a power conversion device according to claim 6, the second circuit having the second switch; A method for controlling a power conversion device.

8. 7. The method for controlling a power conversion device according to claim 6, the third circuit includes the second switch; A method for controlling a power conversion device.

9. 7. The method for controlling a power conversion device according to claim 6, The third circuit includes a main circuit that converts power input from the third coil, and a DC / AC inverter that receives the power converted by the main circuit. A method for controlling a power conversion device.

10. 3. The method for controlling a power conversion device according to claim 2, The control unit By reducing the phase, the power value input to the first circuit is increased; By increasing the phase, the power value input to the first circuit is reduced. A method for controlling a power conversion device.

11. 3. The method for controlling a power conversion device according to claim 2, The control unit By reducing the phase difference, a power value converted by one of the second circuit and the third circuit is reduced, and a power value converted by the other of the second circuit and the third circuit is increased; By increasing the phase difference, the power value converted by one of the second circuit and the third circuit is increased, and the power value converted by the other of the second circuit and the third circuit is decreased. A method for controlling a power conversion device.

12. 3. The method for controlling a power conversion device according to claim 2, The control unit controls the phase and the phase difference within a range of 0° to 180°. A method for controlling a power conversion device.

13. The method for controlling a power conversion device according to claim 12, The control unit controls the phase difference within a range of 0° to 90°. A method for controlling a power conversion device.

14. 3. The method for controlling a power conversion device according to claim 1 or 2, the third circuit includes a main circuit that converts power output from the third coil, and a DC / AC inverter that receives the power converted by the main circuit; the DCAC inverter has the second switch; a maximum allowable power value of the transformer is smaller than a sum of a maximum allowable power value of the second circuit and a maximum allowable power value of the third circuit; the control unit limits the power input to the third circuit so that a total value of the power input to the second circuit and the power input to the third circuit does not exceed a first specified value. A method for controlling a power conversion device.

15. The method for controlling a power conversion device according to claim 14, the first specified value is a maximum allowable power value of the transformer; A method for controlling a power conversion device.

16. The method for controlling a power conversion device according to claim 14, the control unit, when limiting the power input to the third circuit, releases the limit on the power input to the third circuit when the power value input to the second circuit becomes equal to or less than a second specified value. A method for controlling a power conversion device.

17. The method for controlling a power conversion device according to claim 16, the second specified value is a value obtained by subtracting the maximum allowable power value of the third circuit from the maximum allowable power value of the first circuit. A method for controlling a power conversion device.

18. The method for controlling a power conversion device according to claim 16, the second specified value is a value obtained by subtracting the power value input to the third circuit immediately before the power restriction is initiated from the maximum allowable power value of the first circuit. A method for controlling a power conversion device.

19. The method for controlling a power conversion device according to claim 17, the control unit, when limiting the power input to the third circuit, receives a power supply command to the third circuit and the power value input to the second circuit becomes equal to or less than a second specified value, releases the limit on the power input to the third circuit. A method for controlling a power conversion device.

20. a first circuit having a first switch for converting input power; a transformer having a first coil to which the power converted by the first circuit is input, a second coil that converts the voltage input to the first coil and outputs the converted voltage, and a third coil that converts the voltage input to the first coil and outputs the converted voltage; a second circuit that converts the power output from the second coil; a third circuit that converts the power output from the third coil; a control unit, One of the second circuit and the third circuit has a second switch.

1. A power conversion system comprising: The control unit Recognizing a state of power input to the first circuit, a state of power converted by the second circuit, and a state of power converted by the third circuit; controlling the first switch and the second switch based on the recognized state of the power, thereby controlling the powers converted by the second circuit and the third circuit; Power conversion systems.

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