Power conversion device

Abstract

When the battery (92) is charged, the switch (SW1) is turned on, the first step-up chopper circuit, the second step-up chopper circuit, and the totem-pole bridgeless PFC connected in parallel are operated in an interleaved manner, and the AC voltage input from the AC input terminal (P AC1 ) is converted into DC and output from the DC output terminal (P DC ). When the AC output terminal (P AC2 ) is used to output AC, the switch (SW1) is turned on, the totem-pole bridgeless PFC is used to convert the DC voltage from the battery (92) into AC, and the AC is output from the AC output terminal (P AC2 ).

Description

Technical Field

[0001] This invention relates to a power conversion device for converting alternating current (AC) power to direct current (DC) power. Background Technology

[0002] Electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs), which have been gaining popularity in recent years, use AC chargers installed in their own garages or similar locations for charging. AC voltage is applied to the charger's plug, therefore a power-saving converter (PFC) is installed on the vehicle side of the EV or PHEV.

[0003] Furthermore, it is known that because EVs or PHEVs have large-capacity batteries in the vehicle body, these batteries can be used as power sources to output AC voltage from the AC socket via a DC-AC inverter, allowing users to use general-purpose electronic devices inside the vehicle.

[0004] Patent document 1 describes a multiphase PFC converter having a rectifier circuit based on a bridge diode and multiple boost chopper circuits.

[0005] Patent document 2 describes several totem pole bridgeless PFC (power factor improvement) converters.

[0006] Prior art literature

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2012-90423

[0009] Patent Document 2: Japanese Patent Publication No. 2016-533147 Summary of the Invention

[0010] The problem the invention aims to solve

[0011] While the PFC converter described in Patent Document 1 is low-cost, it cannot transmit power bidirectionally because it uses a diode bridge for rectification. Therefore, if an AC outlet is to be installed in the vehicle, a separate DC-AC inverter is required.

[0012] In the totem-pole bridgeless PFC converter described in Patent Document 2, power can be transmitted bidirectionally. Therefore, when an AC socket is installed, there is no need to prepare a separate DC-AC inverter. Moreover, since diodes are not used, power conversion efficiency can be improved. However, if the number of switching elements increases and expensive switching elements such as SiC and GaN are used, it will lead to a significant increase in cost.

[0013] Therefore, the object of the present invention is to provide a power conversion device for charging electric vehicles such as EVs and PHEVs that have large-capacity batteries, wherein high efficiency is achieved when charging the battery from the power system as originally intended, and no additional DC-AC inverter is required when setting up an AC socket, and it is implemented inexpensively.

[0014] Technical solutions for solving the problem

[0015] The power conversion device of the present invention includes: an AC voltage input terminal; a first PFC converter and a second PFC converter connected to the AC voltage input terminal and connected in parallel with each other; and a DC voltage output terminal for combining and outputting the outputs of the first PFC converter and the second PFC converter. The first PFC converter is a diode-rectified PFC converter. The second PFC converter is a totem-pole bridgeless PFC converter. The power conversion device further includes: a switch connected to a second PFC side connection line connecting the AC voltage input terminal and the second PFC converter; and an AC voltage output terminal connected to the second PFC side connection line. The power conversion device selectively executes any one of the following modes through the operation control of the first PFC converter and the on / off control of the switch: mode 1, mode 2, and direct output mode; or a combination of mode 1 and mode 2; or a combination of mode 1 and direct output mode. In mode 1, the AC voltage from the AC voltage input terminal is converted into DC voltage and the DC voltage is output from the DC voltage output terminal. In mode 2, the DC voltage from the DC voltage output terminal is converted into AC voltage and the AC voltage is output from the AC voltage output terminal. In direct output mode, the AC voltage from the AC voltage input terminal is output from the AC voltage output terminal.

[0016] In this structure, an irreversible first PFC converter and a reversible second PFC converter are connected in parallel. This enables bidirectional power supply of both AC and DC. Furthermore, compared to the second PFC converter, the first PFC converter is easier and cheaper to construct, and even at a lower cost, its loss performance is less likely to deteriorate.

[0017] Invention Effects

[0018] According to the present invention, bidirectional power supply of AC and DC can be achieved with low loss and low cost. Attached Figure Description

[0019] Figure 1 This is a diagram illustrating an example of an application system of a power conversion device according to an embodiment of the present invention.

[0020] Figure 2This is an equivalent circuit diagram of the converter (power conversion device) according to the first embodiment of the present invention.

[0021] Figure 3 This is an equivalent circuit diagram showing the connection method of the converter when charging the battery.

[0022] Figure 4 (A) Figure 4 (G) shows various waveforms during charging.

[0023] Figure 5 This is an equivalent circuit diagram showing the connection method of the converter when the DC power charged to the battery is supplied to the outside from the AC output terminal.

[0024] Figure 6 (A) Figure 6 (D) shows various waveforms when the DC voltage of the battery is converted and AC voltage is supplied from the AC output terminal.

[0025] Figure 7 This is an equivalent circuit diagram of the converter (power conversion device) according to the second embodiment of the present invention.

[0026] Figure 8 This is an equivalent circuit diagram showing the connection method of the converter when charging the battery.

[0027] Figure 9 This is an equivalent circuit diagram showing the connection method of the converter when charging the battery and supplying AC voltage simultaneously.

[0028] Figure 10 This is an equivalent circuit diagram showing the connection method of the converter when the DC power charged to the battery is supplied to the outside from the AC output terminal.

[0029] Figure 11 (A) Figure 11 (G) shows various waveforms when charging a small load.

[0030] Figure 12 (A) Figure 12 (G) shows various waveforms when charging in both discontinuous and continuous current modes. Detailed Implementation

[0031] [First Implementation]

[0032] The power conversion device according to the first embodiment of the present invention will be described with reference to the figures.

[0033] (An example of an applicable system)

[0034] Figure 1This is a diagram illustrating an example of an application system of a power conversion device according to an embodiment of the present invention.

[0035] like Figure 1 As shown, for example, the converter 10 according to the first embodiment of the present invention can be applied to an electric vehicle 90. Furthermore, not limited to electric vehicles, the converter 10 of this embodiment can also be applied to a plug-in hybrid vehicle. The electric vehicle 90 includes the converter 10, a DC-DC converter 91, a battery 92, an AC power socket 93, and an AC socket 94. The converter 10 corresponds to the "power conversion device" of the present invention, and the battery 92 corresponds to the "DC load" of the present invention.

[0036] AC power socket 93 is connected to converter 10. Converter 10 is connected to DC-DC converter 91 and AC socket 94. DC-DC converter 91 is connected to battery 92.

[0037] In general, in this system, while the battery 92 is being charged, an external power supply cable 910 is installed in the AC power socket 93. The power supply cable 910 is connected to an external charger 900. Thus, AC voltage is supplied from the charger 900 to the AC power socket 93 via the power supply cable 910.

[0038] The converter 10 has a bidirectional PFC circuit function, converting the AC voltage from the AC power socket 93 into a DC voltage and outputting it to the DC-DC converter 91. The DC-DC converter 91 converts the output voltage from the converter 10 into a charging voltage for the battery 92 and outputs it to the battery 92. The battery 92 is charged using this charging voltage.

[0039] Furthermore, in this system, when AC voltage is output from AC socket 94, DC voltage is supplied from battery 92.

[0040] As described above, the converter 10 has the function of a bidirectional PFC circuit, thus converting the DC voltage from the battery 92 into AC voltage and outputting AC voltage to AC loads (e.g., electrified products) connected to the AC socket 94 via the AC socket 94.

[0041] (Structure of converter 10)

[0042] Figure 2This is an equivalent circuit diagram of the converter (power conversion device) according to the first embodiment of the present invention. The converter 10 includes a diode bridge DB, inductors L1, L2, and L3, switching elements Q1, Q2, Q3, Q4, Q5, and Q6, diodes D1 and D2, capacitor Co, switch SW1, and control IC 11. Furthermore, the converter 10 includes an AC input terminal P. AC1 DC output terminal P DC and AC output terminal P AC2 .

[0043] Switching elements Q1, Q2, Q5, and Q6 are silicon semiconductor Si-MOSFETs. Switching elements Q3 and Q4 are gallium nitride semiconductor GaN-FETs.

[0044] The AC input terminals of the diode bridge DB and AC input terminal P AC1 Connections. The Hi-side output terminal of the diode bridge DB is connected to one end of inductor L1 and one end of inductor L2.

[0045] The low-side output terminal of the diode bridge DB is connected to the reference potential line. The reference potential line is connected to the DC output terminal P. DC The reference potential side.

[0046] The anode of diode D1 is connected to the other end of inductor L1. Additionally, the drain of switching element Q1 is connected to the other end of inductor L1. The source of switching element Q1 is connected to the reference potential line. The cathode of diode D1 is connected to the DC output terminal P. DC The Hi potential side. The first boost chopper circuit is composed of these inductors L1, switching element Q1, and diode D1.

[0047] The anode of diode D2 is connected to the other end of inductor L2. Additionally, the drain of switching element Q2 is connected to the other end of inductor L2. The source of switching element Q2 is connected to the reference potential line. The cathode of diode D2 is connected to the DC output terminal P. DC The Hi potential side. The second boost chopper circuit is composed of inductor L2, switching element Q2, and diode D2.

[0048] Moreover, the first boost chopper circuit and the second boost chopper circuit correspond to the "first PFC converter" of the present invention.

[0049] One end of inductor L3 is connected to AC input terminal P AC1One terminal of the inductor L3 is connected. The other terminal of the inductor L3 is connected to the node between the drain of the switching element Q3 and the source of the switching element Q4. The source of the switching element Q3 is connected to the reference potential line. The drain of the switching element Q4 is connected to the DC output terminal P. DC The Hi potential side.

[0050] The node between the drain of switching element Q5 and the source of switching element Q6 and the AC input terminal P AC1 One terminal is connected. The source of switching element Q5 is connected to the reference potential line. The drain of switching element Q6 is connected to the DC output terminal P. DC The Hi potential side. These inductors L3, switching elements Q3, Q4, Q5, and Q6 constitute a totem-pole bridgeless PFC. This totem-pole bridgeless PFC is equivalent to the "second PFC converter" of this invention.

[0051] Furthermore, these structures enable parallel operation of one phase containing a diode bridge (DB) and a first boost chopper circuit, one phase containing a diode bridge (DB) and a second boost chopper circuit, and one phase containing a totem-pole bridgeless PFC. That is, two phases are implemented using a diode bridge (DB) and a boost chopper circuit, while one phase is implemented using a totem-pole bridgeless PFC.

[0052] Capacitor Co is connected to DC output terminal P DC Hi potential side and DC output terminal P DC Between the reference potential sides.

[0053] The control IC11 is connected to the gates of multiple (six in this embodiment) switching elements Q1 to Q6, and outputs switching control signals to the multiple switching elements Q1 to Q6. In other words, the multiple switching elements Q1 to Q6 are driven and controlled by the switching control signals from the control IC11.

[0054] Switch SW1 is connected to the AC input terminal P. AC1 The second PFC side connection line connecting to the totem pole bridgeless PFC is connected to the AC output terminal P. AC2 Between. Switch SW1 connects to the second PFC side wire and the AC output terminal P. AC2 Control the conduction or open circuit between them.

[0055] (When charging battery 92 (Method 1))

[0056] Figure 3 This is an equivalent circuit diagram showing the connection method of the converter when charging the battery. For example... Figure 3 As shown, at the DC output terminal P DC Connect the battery 92. Additionally, connect the AC input terminal P. AC1. Connect to charger 900.

[0057] When charging the battery 92, the switch SW1 is disconnected. In other words, the switch SW1 is controlled to be in an open circuit state. However, although this embodiment shows the method of disconnecting the switch SW1 when charging the battery 92, it is also possible to connect the switch SW1 (control it to a conducting state). In this case, it is possible to simultaneously charge the battery 92 and output power from the AC output terminal P. AC2 Output AC voltage.

[0058] In this state, control IC11 outputs switching control signals to multiple switching elements Q1 to Q6. More specifically, control IC11 outputs switching control signals to multiple switching elements Q1 to Q6, causing the first boost chopper circuit, the second boost chopper circuit, and the totem pole bridgeless PFC to operate alternately.

[0059] Figure 4 (A) Figure 4 (G) shows various waveforms during charging. Figure 4 (A) Figure 4 (B) Figure 4 (C) shows an example of the waveforms of the switching control signals for each of the switching elements Q1, Q2, and Q4. Figure 4 (D) Figure 4 (E) Figure 4 (F) shows an example of the waveform of the inductor current of inductors L1, L2, and L3. Figure 4 (G) indicates the AC input terminal P AC1 Here is an example of the current waveform. Additionally, the waveforms of switching elements Q3, Q5, and Q6 are not shown. The waveform of switching element Q5 is the same as that of switching element Q4, while the waveforms of switching elements Q3 and Q6 are inverse phase with those of switching element Q4.

[0060] When charging battery 92, such as Figure 4 (A) Figure 4 As shown in (C), switching elements Q1, Q2, and Q4 are staggered by a phase difference of 120° to achieve on / off control. Therefore, as... Figure 4 (D)~ Figure 4 As shown in (F), the inductor current IL1 of the inductor L1 in the first boost chopper circuit, the inductor current IL2 of the inductor L2 in the second boost chopper circuit, and the inductor current IL3 of the inductor L3 in the totem pole bridgeless PFC also become waveforms with a phase difference of 120° between them, and the ripple current superimposed on their respective DC components are also staggered by 120°.

[0061] AC input terminal P AC1 The current Icin is the sum of the inductor currents IL1, IL2, and IL3. Therefore, since the inductor currents IL1, IL2, and IL3 have a 120° phase difference as described above, they work together to cancel out their respective ripple currents. Thus, as... Figure 4 As shown in (G), the AC input terminal P can be suppressed. AC1 The amplitude of the ripple current of the current Icin.

[0062] By performing this control, the converter 10 will transfer power from the AC input terminal P. AC1 The input AC voltage is converted into DC voltage and output from DC output terminal P. DC Output. The battery 92 is charged using the DC voltage output. At this time, by performing the above-described control, harmonic currents and noise generated from the converter 10 can be suppressed.

[0063] (The DC power that charges the battery 92 is transferred from the AC output terminal P) AC2 When supplying externally (method 2)

[0064] Figure 5 This is an equivalent circuit diagram showing the connection configuration of the converter when supplying DC power charged to the battery from the AC output terminal to the external circuit. For example... Figure 5 As shown, at the DC output terminal P DC Connect the battery 92. Additionally, connect the AC output terminal P. AC2 Connect load 940. Load 940 is an AC load.

[0065] The DC power that charges the battery 92 is supplied from the AC output terminal P. AC2 When supplies are supplied to the outside, switch SW1 is turned on. In other words, switch SW1 is controlled to be in the on state.

[0066] Both the first and second boost chopper circuits are unidirectional PFC converters, therefore they cannot output voltage from the DC output terminal P. DC The input DC voltage is converted to AC and fed into the AC input terminal P. AC1 Side output. Therefore, stop control is applied to both the first boost chopper circuit and the second boost chopper circuit.

[0067] Totem pole bridgeless PFC can transmit power bidirectionally, thus enabling power transfer from the DC output terminal P... DC The input DC voltage is converted to AC and fed into the AC input terminal P. AC1 and AC output terminal P AC2Side output. Therefore, the totem pole bridgeless PFC is driven and controlled.

[0068] By performing this control, converter 10 will output power from DC output terminal P. DC The input DC voltage is converted into AC voltage and output from AC output terminal P. AC2 Output. The AC voltage from this output is supplied to the load 940.

[0069] At this time, the switching elements of the totem pole bridgeless PFC are preferably driven at a higher switching frequency than when the battery 92 is being charged.

[0070] Figure 6 (A) Figure 6 (D) shows various waveforms when the DC voltage of the battery is converted and AC voltage is supplied from the AC output terminal. Figure 6 (A) Figure 6 (C) shows an example of the waveform of the switching control signal for the switching element Q4. Figure 6 (B) Figure 6 (D) shows an example of a waveform superimposed on the transformed AC ripple current. Figure 6 (A) Figure 6 (B) shows that when the switching frequency is high, Figure 6 (C) Figure 6 (D) indicates a low switching frequency. Furthermore, the term "low switching frequency" is the same as the switching frequency during charging described above. Additionally, the term "high switching frequency" is preferably a positive integer multiple of the low switching frequency.

[0071] like Figure 6 (A) Figure 6 As shown in (B), by increasing the switching frequency, the amplitude of the ripple current can be reduced.

[0072] Therefore, even without driving the first boost chopper circuit and the second boost chopper circuit, only driving the totem pole bridgeless PFC can suppress the ripple superimposed on the AC voltage.

[0073] Furthermore, in this structure, GaN-FETs are used only for the switching elements Q3 and Q4 of the totem-pole bridgeless PFC, while Si-MOSFETs are used for the other switching elements Q1, Q2, Q5, and Q6. Therefore, compared to using GaN-FETs for all switching elements Q1 to Q6, the converter 10 can be constructed at a lower cost.

[0074] On the other hand, by using GaN-FETs only for the switching elements Q3 and Q4 of the totem-pole bridgeless PFC, losses caused by inverting recovery characteristics and parasitic capacitance can be suppressed. Therefore, a low-loss converter 10 can be achieved.

[0075] Additionally, at AC input terminal P AC1 and AC output terminal P AC2 When the voltage is the same, the switch SW1 can also be turned on (conduction control) while the battery 92 is being charged. Therefore, the converter 10 can simultaneously charge the battery 92 and charge the battery connected to the AC output terminal P. AC2 The load is supplied with AC power. Furthermore, it would be even better if the converter 10 operated the first boost chopper circuit and the second boost chopper circuit alternately at this time.

[0076] (An example of using this method)

[0077] With the charger 900 providing an AC 220V / 30A, 6.6kW output, this AC voltage is supplied. The converter 10 performs the aforementioned three-phase power conversion and charges the battery 92 with the converted DC power.

[0078] On the other hand, the power that charges the battery 92 is delivered from the AC output terminal P. AC2 In the output case, converter 10 drives only one phase of the totem-pole bridgeless PFC. Therefore, from the AC output terminal P... AC2 It can achieve an output of 2.2kW.

[0079] Furthermore, although the switching elements Q3 and Q4 of the totem pole bridgeless PFC are described using GaN-FET in this embodiment, other wide-bandgap semiconductors such as SiC-FET may also be used as switching elements.

[0080] [Second Implementation]

[0081] The power conversion device according to the second embodiment of the present invention will be described with reference to the figures. Figure 7 This is an equivalent circuit diagram of the converter (power conversion device) according to the second embodiment of the present invention.

[0082] like Figure 7 As shown, the converter 10A according to the second embodiment differs from the converter 10 according to the first embodiment in terms of switch SW2 and AC output terminal P. AC2 The connection methods differ. The other structures of converter 10A are the same as converter 10, so descriptions of the similarities are omitted.

[0083] In converter 10A, AC output terminal P AC2 Connect the second PFC side cable (connect AC input terminal P) AC1 Connect directly to the totem pole via the bridgeless PFC connection cable.

[0084] Switch SW2 is inserted midway into the second PFC side connection line. More specifically, switch SW2 is connected to the totem-pole bridgeless PFC and AC output terminal P in the second PFC side connection line. AC2 Connection part and AC input terminal P AC1 between.

[0085] (When charging battery 92 (Method 1))

[0086] Figure 8 This is an equivalent circuit diagram showing the connection method of the converter when charging the battery. For example... Figure 8 As shown, at the DC output terminal P DC Connect the battery 92. Additionally, connect the AC input terminal P. AC1 Connect charger 900.

[0087] When charging battery 92, switch SW2 is turned on. In other words, switch SW2 is controlled to be in the on state.

[0088] In this state, control IC11 outputs switching control signals to multiple switching elements Q1 to Q6. More specifically, control IC11 outputs switching control signals to multiple switching elements Q1 to Q6, causing the first boost chopper circuit, the second boost chopper circuit, and the totem pole bridgeless PFC to operate alternately.

[0089] By performing this control, converter 10A will output AC input from terminal P. AC1 The input AC voltage is converted into DC voltage and output from DC output terminal P. DC Output. The battery 92 is charged using the DC voltage output. At this time, by performing the above-described control, harmonic current generated from converter 10A can be suppressed.

[0090] (While charging the battery 92, the AC output terminal P is connected to the battery.) AC2 (supplying alternating current power)

[0091] Figure 9 This is an equivalent circuit diagram showing the connection configuration of the converter when simultaneously charging the battery and supplying AC voltage. For example... Figure 9 As shown, at the DC output terminal P DC Connect the battery 92. Additionally, connect the AC input terminal P. AC1 Connect charger 900. Additionally, at AC output terminal P... AC2 The connection load is 940.

[0092] When charging battery 92 and from AC output terminal P AC2When AC power is supplied, switch SW2 is disconnected. In other words, switch SW2 is controlled to be in an open circuit state.

[0093] Switching control is performed so that converter 10A charges battery 92 through the first boost chopper circuit and the second boost chopper circuit. The totem-pole bridgeless PFC is used to charge the AC output terminal P. AC2 The inverter operates by outputting power from the storage battery 92. It would be even better if the converter 10A alternated between the first boost chopper circuit and the second boost chopper circuit.

[0094] Therefore, the converter 10A can charge the battery 92 while simultaneously charging the battery connected to the AC output terminal P. AC2 The load of 940 supplies AC power.

[0095] (The DC power that charges the battery 92 is transferred from the AC output terminal P) AC2 When supplied to external parties (method 2)

[0096] Figure 10 This is an equivalent circuit diagram showing the connection configuration of the converter when supplying DC power charged to the battery from the AC output terminal to the external circuit. For example... Figure 10 As shown, at the DC output terminal P DC Connect the battery 92. Additionally, connect the AC output terminal P. AC2 The connection load is 940.

[0097] The DC power that charges the battery 92 is supplied from the AC output terminal P. AC2 When supplies are being supplied to the outside, switch SW2 is disconnected. In other words, switch SW2 is controlled to be in an open circuit state.

[0098] Stop control is applied to the first and second boost chopper circuits. Drive control is applied to the totem pole bridgeless PFC.

[0099] By performing this control, converter 10A will output power from DC output terminal P. DC The input DC voltage is converted into AC voltage and output from AC output terminal P. AC2 Output. The AC voltage from this output is supplied to the load 940.

[0100] At this time, similar to the first embodiment, the switching element of the totem pole bridgeless PFC is preferably driven at a switching frequency higher than the switching frequency when charging the battery 92. Therefore, even if the first boost chopper circuit and the second boost chopper circuit are not driven, but only the totem pole bridgeless PFC is driven, the ripple superimposed on the load current applied to the load 940 can be suppressed.

[0101] Furthermore, at this time, converter 10A can also drive the first boost chopper circuit and the second boost chopper circuit. That is, converter 10A can also charge the battery 92 through the first boost chopper circuit and the second boost chopper circuit, while simultaneously generating AC voltage from the power of the battery 92 and outputting it from the AC output terminal P. AC2 Output.

[0102] [Third Implementation]

[0103] The power conversion device according to the third embodiment of the present invention will be described with reference to the figures. The converter according to the third embodiment has the same circuit structure as the converter according to the first embodiment. The converter according to the third embodiment differs from the converter according to the first embodiment in its charging control under low load. Other controls of the converter according to the third embodiment are the same as those of the converter according to the first embodiment, and descriptions of the same parts are omitted.

[0104] Figure 11 (A) Figure 11 (G) shows various waveforms when charging in continuous current mode. Figure 12 (A) Figure 12 (G) shows various waveforms when charging in both discontinuous and continuous current modes.

[0105] (Continuous Current Mode)

[0106] Figure 11 (A) Figure 11 (B) Figure 11 (C) shows an example of the waveforms of the switching control signals for each of the switching elements Q1, Q2, and Q4. Figure 11 (D) Figure 11 (E) Figure 11 (F) shows an example of the waveform of the inductor current of inductors L1, L2, and L3. Figure 11 (G) indicates the AC input terminal P AC1 Here is an example of the current waveform. Additionally, the waveforms of switching elements Q3, Q5, and Q6 are not shown. The waveform of switching element Q5 is the same as that of switching element Q4, while the waveforms of switching elements Q3 and Q6 are inverse phase with those of switching element Q4.

[0107] like Figure 11 (A) Figure 11 (B) Figure 11 (D) Figure 11 As shown in (E), under low load, the converter causes the first boost chopper circuit and the second boost chopper circuit to operate in critical mode. Furthermore, as... Figure 11 (C) Figure 11As shown in (F), under low load, the converter enables the totem pole bridgeless PFC to operate in continuous current mode.

[0108] (Combined use of discontinuous current mode and continuous current mode)

[0109] Figure 12 (A) Figure 12 (B) Figure 12 (C) shows an example of the waveforms of the switching control signals for each of the switching elements Q1, Q2, and Q4. Figure 12 (D) Figure 12 (E) Figure 12 (F) shows an example of the waveform of the inductor current of inductors L1, L2, and L3. Figure 12 (G) indicates the AC input terminal P AC Here is an example of the current waveform of switch element Q1. Additionally, the waveforms of switch elements Q3, Q5, and Q6 are not shown in the diagram. The waveform of switch element Q5 is the same as that of switch element Q4, while the waveforms of switch elements Q3 and Q6 are inverse phase with those of switch element Q4.

[0110] like Figure 12 (A) Figure 12 (B) Figure 12 (D) Figure 12 As shown in (E), under low load, the converter causes the first boost chopper circuit and the second boost chopper circuit to operate in a current discontinuous mode. Furthermore, as... Figure 12 (C) Figure 12 As shown in (F), under low load, the converter enables the totem pole bridgeless PFC to operate in continuous current mode.

[0111] Through these controls, under low load, in the first and second boost chopper circuits, only ripple current flows as inductor currents IL1 and IL2, while in the totem pole bridgeless PFC, current with ripple component superimposed on DC component flows as inductor current IL3.

[0112] By implementing such control, the converter actively uses a high-efficiency totem-pole bridgeless PFC for charging under low load conditions. This improves power conversion efficiency under low load conditions. Furthermore, as... Figure 11 (A) Figure 11 As shown in (B), under this control, the switching elements of the first and second boost chopper circuits are turned on when the current is 0. This reduces the switching losses of the first and second boost chopper circuits, further improving the power conversion efficiency of the converter.

[0113] Furthermore, under this control, similar to the first embodiment, the first boost chopper circuit, the second boost chopper circuit, and the totem pole bridgeless PFC operate in an alternating manner, thereby suppressing ripple current.

[0114] Furthermore, under low load conditions, both the first and second boost chopper circuits can be stopped. In this case, it is advisable to increase the switching frequency of the totem-pole bridgeless PFC. For example, it is advisable to set the switching frequency of the totem-pole bridgeless PFC to three times that when it operates alternately with the first and second boost chopper circuits. Thus, even when the totem-pole bridgeless PFC operates alone, ripple current can be suppressed.

[0115] Explanation of reference numerals in the attached figures

[0116] 10, 10A: Converter;

[0117] 11: Control IC;

[0118] 90: Electric vehicles;

[0119] 91: DC-DC converter;

[0120] 92: Storage battery;

[0121] 93: AC power socket;

[0122] 94: AC socket;

[0123] 900: Charger;

[0124] 910: Power supply cable;

[0125] 940: Load;

[0126] Co: Capacitor;

[0127] D1, D2: Diodes;

[0128] DB: Diode bridge;

[0129] L1, L2, L3: Inductors;

[0130] P AC1 AC input terminal;

[0131] P AC2 AC output terminal;

[0132] P DC DC output terminal;

[0133] Q1, Q2, Q3, Q4, Q5, Q6: Switching elements;

[0134] SW1, SW2: Switches.

Claims

1. A power conversion device, comprising: AC voltage input terminal; The first PFC converter and the second PFC converter are connected to the AC voltage input terminal and are connected in parallel with each other; and The DC voltage output terminal combines and outputs the outputs of the first PFC converter and the second PFC converter. in, The first PFC converter is composed of a diode rectifier type PFC converter. The second PFC converter is composed of a totem-pole bridgeless PFC converter. The power conversion device also includes: The switch is connected to the second PFC side connection line that connects the AC voltage input terminal and the second PFC converter; and The AC voltage output terminal is connected to the second PFC side connection line. The power conversion device selectively executes any one of the following modes through the operation control of the first PFC converter and the second PFC converter and the on / off control of the switch: mode 1, mode 2, and direct output mode; or a combination of mode 1 and mode 2; or a combination of mode 1 and direct output mode. In the first mode, the AC voltage from the AC voltage input terminal is converted into a DC voltage, and the DC voltage is output from the DC voltage output terminal. In the second method, the DC voltage from the DC voltage output terminal is converted into an AC voltage, and this AC voltage is output from the AC voltage output terminal. In the direct-connection output mode, the AC voltage from the AC voltage input terminal is output from the AC voltage output terminal.

2. The power conversion device according to claim 1, wherein, The switch is connected between the second PFC side connection line and the AC voltage output terminal.

3. The power conversion device according to claim 1, wherein, The switch is connected in the connection line of the second PFC side between the connection portion of the second PFC converter and the AC voltage output terminal and the AC voltage input terminal.

4. The power conversion device according to any one of claims 1 to 3, wherein, The first PFC converter and the second PFC converter operate alternately.

5. The power conversion device according to any one of claims 1 to 3, wherein, The second PFC converter uses gallium nitride semiconductor switching elements.

6. The power conversion device according to claim 5, wherein, The switching frequency of the gallium nitride semiconductor switching element in the second mode is higher than that in the first mode.

7. The power conversion device according to any one of claims 1 to 3, wherein, When the DC load connected to the DC voltage output terminal is a small load. The first PFC converter is driven in critical mode or current discontinuous mode. The second PFC converter is driven in continuous current mode.

8. The power conversion device according to any one of claims 1 to 3, wherein, When the DC load connected to the DC voltage output terminal is a small load. Stop driving the first PFC converter and start driving the second PFC converter. Increase the switching frequency of the switching elements constituting the second PFC converter.

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