Power conversion device

Abstract

A current resonance converter is included in the rear stage of a boost converter, and high efficiency is achieved even when the input voltage of the boost converter can be at two or more input voltage levels. In a power conversion device, a control circuit sets an output voltage of a boost converter to a first output voltage level or a second output voltage level on the basis of a voltage detected by an input voltage detection circuit that detects a voltage corresponding to an input voltage, and when the first output voltage level is set, the control circuit controls the boost converter to output the first output voltage level or the second output voltage level. When the first output voltage level is set, the current resonant converter is operated in a full-bridge operation mode, and when the second output voltage level is set, the current resonant converter is operated in a half-bridge operation mode, and the first output voltage level or the second output voltage level is set at a predetermined timing after the input voltage is input. The operation mode is maintained until the setting of the first output voltage level or the second output voltage level is reset.

Description

Technical Field

[0001] The present invention relates to a power conversion device. Background Art

[0002] In a power conversion device including a current resonance converter at a subsequent stage of a boost converter, the input voltage of the boost converter may be at two or more input voltage levels. As a specific example, the input voltage level may differ depending on the country in which the power conversion device is used.

[0003] Patent Document 1 describes that, in a current resonance converter that converts a DC input voltage into an AC, a full-bridge switching circuit and a half-bridge switching circuit are switched according to the DC input voltage (see Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 3-289354 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, in the conventional technology described above, in a power conversion device including a current resonance converter at a subsequent stage of a boost converter, when two or more input voltage levels are possible, efficiency may be reduced.

[0009] The present invention has been completed in consideration of such a situation, and its object is to provide a power conversion device which, in a structure including a current resonance converter at the subsequent stage of a boost converter, can achieve high efficiency even when the input voltage of the boost converter can have more than two input voltage levels.

[0010] Methods for solving problems

[0011] One embodiment is a power conversion device, comprising: a boost converter; a current resonance type converter connected to a subsequent stage of the boost converter; and a control circuit, wherein the boost converter boosts an input voltage to obtain an output voltage, charges a first output capacitor with the output voltage, and outputs the output voltage, wherein the control circuit controls the boost converter based on a voltage detected by an output voltage detection circuit that detects a voltage of the first output capacitor, and the control circuit sets the output voltage of the boost converter to the first output voltage according to a voltage detected by an input voltage detection circuit that detects a voltage corresponding to the input voltage. The output voltage detection circuit and the input voltage detection circuit are common circuits or separate circuits. The first output voltage level or the second output voltage level is set at a specified time from the input of the input voltage, and the operating mode set to the first output voltage level or the second output voltage level is maintained until the setting of the first output voltage level or the second output voltage level is reset.

[0012] Effects of the Invention

[0013] According to the present invention, in a power conversion device including a current resonance converter at a subsequent stage of a boost converter, high efficiency can be achieved even when the input voltage of the boost converter can have two or more input voltage levels. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a diagram showing a configuration example of a circuit of the power conversion system according to the first embodiment.

[0015] Figure 2A This is a diagram showing an example of switching loss of a switching element.

[0016] Figure 2B This is a diagram showing another example of switching loss of a switching element.

[0017] Figure 2C This is a diagram showing another example of switching loss of a switching element.

[0018] Figure 3 This is a diagram showing an example of switching loss and conduction loss of a switching element.

[0019] Figure 4A This is a diagram showing an example of the relationship between the operating frequency and the output voltage ratio of the current resonance converter.

[0020] Figure 4BThis is a diagram showing another example of the relationship between the operating frequency and the output voltage ratio of the current resonance converter.

[0021] Figure 5A This is a diagram showing an example of the relationship between the AC input voltage and the output voltage for explaining the switching between the full-bridge operation and the half-bridge operation according to the embodiment.

[0022] Figure 5B It is a diagram showing a state of a half-bridge operation in the current resonance converter according to the embodiment.

[0023] Figure 5C It is a diagram showing a state of a full-bridge operation in the current resonance converter according to the embodiment.

[0024] Figure 5D This is a diagram showing an example of a voltage applied to the primary side of the transformer during the half-bridge operation according to the embodiment.

[0025] Figure 5E This is a diagram showing an example of a voltage applied to the primary side of a transformer during full-bridge operation according to the embodiment.

[0026] Fig. 6A It is a diagram showing an example of a drive signal switching circuit according to an embodiment.

[0027] Figure 6B 1 is a diagram showing an example of input and output signals of the drive signal switching circuit according to the embodiment.

[0028] Figure 7 It is a diagram showing a configuration example of a circuit of a power conversion system according to the second embodiment.

[0029] Figure 8 It is a diagram showing a processing flow of an example of the boost voltage selection processing according to the second embodiment.

[0030] Fig.9A It is a diagram showing a configuration example of a circuit of a power conversion system according to a third embodiment.

[0031] Fig. 9B This is a diagram of a table showing an example of the relationship among the input voltage, the output voltage of the boost converter, and the operation mode of the current resonance converter according to the third embodiment.

[0032] Fig.10 It is a diagram showing a configuration example of a circuit of a power conversion system according to a fourth embodiment.

[0033] Fig.11 It is a diagram showing a configuration example of a circuit of a power conversion system according to a fifth embodiment.

[0034] Fig.12It is a diagram showing a configuration example of a circuit of a power conversion system according to a sixth embodiment. DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0036] (First embodiment)

[0037] The first embodiment will be described.

[0038] [Power conversion system]

[0039] Figure 1 1 is a diagram showing a configuration example of a circuit of a power conversion system A1 according to the first embodiment. The power conversion system A1 includes a power conversion device 1 , a single-phase AC power supply 11 , and a resistor 12 .

[0040] The power conversion device 1 includes a boost converter B1 , a current resonance converter B2 , and a control circuit 111 .

[0041] In the present embodiment, the current resonance converter B2 is an LLC type.

[0042] The current resonance converter B2 is connected to the subsequent stage of the boost converter B1.

[0043] In the present embodiment, a case where the input voltage of the boost converter B1 is a single-phase AC is shown.

[0044] In addition, in this embodiment, the AC power supply 11 and the resistor 12 are external circuits of the power conversion device 1, but as another example, a structure in which one or both of the AC power supply 11 and the resistor 12 are internal circuits of the power conversion device 1 can also be used.

[0045] For example, when both the AC power source 11 and the resistor 12 are circuits inside the power conversion device 1 , the power conversion system A1 of the present embodiment is equal to the power conversion device 1 .

[0046] Boost converter B1 includes a diode bridge 31 , an inductor 32 , a diode 33 , a capacitor 34 , and a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) Q1 as a switching element.

[0047] The current resonance converter B2 includes: four MOSFETs Q11 to Q14 as switching elements; an inductor 51 ; a primary winding 52 ; a capacitor 53 ; secondary windings 71 and 72 ; two diodes 91 and 92 ; and a capacitor 93 .

[0048] The control circuit 111 includes a boost converter control circuit 131 , a voltage detection circuit 132 , an operation mode setting circuit 133 , and a current resonance type converter drive circuit 134 .

[0049] The voltage detection circuit 132 includes an input voltage detection circuit 151 and an output voltage detection circuit 152 .

[0050] Here, the transformer TR1 is composed of the primary winding 52 and the secondary windings 71 and 72. In the present embodiment, the secondary windings 71 and 72 are divided into two parts by a center tap method relative to the center tap point. For the sake of convenience, they are respectively referred to as the secondary winding 71 and the secondary winding 72. The secondary winding 71 and the secondary winding 72 may also be integrated.

[0051] In addition, MOSFETs Q1 and Q11 to Q14 as switching elements in the present embodiment are a type of power semiconductor element.

[0052] Furthermore, in this embodiment (and subsequent embodiments), the body diode of the MOSFET is also illustrated.

[0053] In addition, the switching element is not limited to MOSFET, and power semiconductor elements such as bipolar transistors (or unipolar transistors), GaN transistors (Gallium Nitride Transistor), IGBTs (Insulated Gate Bipolar Transistor), and SiCFETs (Silicon Carbide Field Effect Transistor) may also be used.

[0054] <Circuit connection relationship>

[0055] Two of the four terminals of the diode bridge 31 are connected to two terminals of the AC power source 11 , respectively.

[0056] One of the other two terminals of the diode bridge 31 is connected to one end of the inductor 32 .

[0057] The other of the other two terminals of the diode bridge 31 , the source of the MOSFET Q1 , one end of the capacitor 34 , the source of the MOSFET Q12 , and the source of the MOSFET Q14 are connected.

[0058] The other end of the inductor 32 , the anode of the diode 33 , and the drain of the MOSFET Q1 are connected.

[0059] The cathode of the diode 33 , the drain of the MOSFET Q11 , the drain of the MOSFET Q13 , and the other end of the capacitor 34 are connected.

[0060] The source of the MOSFET Q11 , the drain of the MOSFET Q12 , and one end of the inductor 51 are connected.

[0061] The other end of the inductor 51 is connected to one end of the primary winding 52 .

[0062] The other end of the primary winding 52 is connected to one end of the capacitor 53 .

[0063] The other end of the capacitor 53, the source of the MOSFET Q13, and the drain of the MOSFET Q14 are connected.

[0064] One end of the secondary winding 71 is connected to the anode of the diode 91 .

[0065] One end of the secondary winding 72 is connected to the anode of the diode 92 .

[0066] The cathode of the diode 91 , the cathode of the diode 92 , one end of the capacitor 93 , and one end of the resistor 12 are connected.

[0067] The other end of the secondary winding 71 and the other end of the secondary winding 72 are common, and the common end, the other end of the capacitor 93 and the other end of the resistor 12 are connected.

[0068] Thus, in this embodiment, the current resonant converter B2 includes: a bridge arm formed by connecting MOSFETQ11 and MOSFETQ12 in series; a bridge arm formed by connecting MOSFETQ13 and MOSFETQ14 in series; a transformer TR1 having a primary winding 52 and secondary windings 71 and 72; a resonant inductor (inductor 51); a resonant capacitor (capacitor 53); and a rectifier circuit (a circuit including diodes 91 and 92).

[0069] The two bridge arms are connected in parallel.

[0070] In the circuit on the primary side of transformer TR1 (primary side circuit), both ends of the primary winding 52 are connected to two connection points, namely, the connection point between MOSFETQ11 and MOSFETQ12 and the connection point between MOSFETQ13 and MOSFETQ14, via a resonant inductor (inductor 51) and a resonant capacitor (capacitor 53).

[0071] In the circuit on the secondary side of the transformer TR1 (secondary side circuit), both ends of the secondary winding 71 and the secondary winding 72 are connected to the input end of the rectifier circuit (the anode of the diode 91 and the anode of the diode 92 ).

[0072] The input voltage detection circuit 151 detects a voltage corresponding to the input voltage (Vin) to the power conversion device 1 (boost converter B1). In the present embodiment, the input voltage detection circuit 151 has a function of detecting a voltage corresponding to the potential of the other end of the capacitor 34 (the potential of the cathode of the diode 33). The input voltage detection circuit 151 detects the voltage applied to both ends of the capacitor 34 as the voltage.

[0073] The output voltage detection circuit 152 detects the output voltage. In the present embodiment, the output voltage detection circuit 152 has a function of detecting a voltage corresponding to the potential of the other end of the capacitor 34 (the potential of the cathode of the diode 33). The output voltage detection circuit 152 detects the voltage applied to both ends of the capacitor 34 as the voltage.

[0074] In addition, the term "detection" may be referred to as "determination" or "measurement".

[0075] Here, the input voltage detection circuit 151 only needs to be able to detect a voltage corresponding to the input voltage (Vin). As another example, it can detect a voltage corresponding to the potential between one end of the AC power supply 11 and the diode bridge 31, or it can detect a voltage corresponding to the potential between the diode bridge 31 and the inductor 32.

[0076] In the present embodiment, the input voltage detection circuit 151 detects a voltage that is referred to in order to determine the system of the input voltage (in the present embodiment, the 200 VAC system or the 400 VAC system).

[0077] Furthermore, a reference value (for example, a threshold value) regarding the voltage is set according to the voltage detected by the input voltage detection circuit 151. That is, the threshold value may be changed according to the voltage detected as a voltage corresponding to the input voltage.

[0078] Furthermore, output voltage detection circuit 152 detects a voltage (output voltage) that is used as a reference in order to maintain the output voltage of boost converter B1 constant.

[0079] Therefore, the input voltage detection circuit 151 can also detect a voltage at a point different from the voltage detected by the output voltage detection circuit 152 .

[0080] In addition, in the present embodiment, the input voltage detection circuit 151 and the output voltage detection circuit 152 detect the same voltage, so they may also be shared.

[0081] The boost converter control circuit 131 has a function of outputting a control voltage to the gate of the MOSFET Q1 .

[0082] In the present embodiment, boost converter control circuit 131 performs control to maintain the output voltage of boost converter B1 at a predetermined value based on the voltage detected by output voltage detection circuit 152 .

[0083] In the present embodiment, the predetermined value can be switched to a plurality of values ​​(380 V, 760 V).

[0084] The operation mode setting circuit 133 has a function of setting the operation mode.

[0085] The current resonance type converter drive circuit 134 has a function of outputting a control voltage to the gate of the MOSFET Q11 according to the operation mode, and a function of outputting a control voltage to the gate of the MOSFET Q12 according to the operation mode.

[0086] In addition, the current resonance type converter driving circuit 134 has a function of outputting a control voltage to the gate of the MOSFET Q13 according to the operation mode, and a function of outputting a control voltage to the gate of the MOSFET Q14 according to the operation mode.

[0087] In the present embodiment, the input voltage detection circuit 151 detects a voltage corresponding to the input voltage (Vin), the operation mode setting circuit 133 sets the operation mode based on the detected voltage, and the boost converter control circuit 131 and the current resonance type converter drive circuit 134 operate respectively based on the set operation mode. At this time, the operation mode setting circuit 133 determines the target boost voltage and notifies the boost converter control circuit 131 of the determined target boost voltage. The boost converter control circuit 131 controls the MOSFET Q1 (feedback control) based on the detection voltage of the output voltage detection circuit 152 so that the output voltage becomes constant (the target boost voltage).

[0088] Here, the control circuit 111 may be constituted by, for example, a microcomputer or the like.

[0089] In this embodiment, for ease of explanation, the boost converter control circuit 131, the voltage detection circuit 132, the operation mode setting circuit 133 and the current resonance type converter drive circuit 134 are shown inside the control circuit 111, but the functions inside the control circuit 111 do not need to be clearly distinguished.

[0090] In addition, as another example, the function of the control circuit 111 may be separated into a plurality of circuit units.

[0091] <Examples of usage environments of power conversion devices>

[0092] An example of an environment in which the power conversion device 1 according to the present embodiment is used will be described.

[0093] In the present embodiment, description will be given assuming an environment in which the input voltage to the boost converter B1 of the power conversion device 1 can have two or more input voltage levels.

[0094] As such an environment, for example, a case where the voltage of a power source that supplies an input voltage to the boost converter B1 of the power conversion device 1 differs depending on the country or the like is considered.

[0095] In this embodiment, a system in which the voltage of the public power supply in a first country is 200 V AC (200 VAC system) and a system in which the voltage of the public power supply in a second country different from the first country is 400 V AC (400 VAC system) is exemplified.

[0096] Here, in the 200VAC system, for example, alternating current (AC) of 200 to 240V is supplied.

[0097] In addition, in a 400VAC system, for example, alternating current (AC) of 400 to 480V is supplied.

[0098] As described above, in the present embodiment, the input voltage to the boost converter B1 of the power conversion device 1 can be wide.

[0099] As a specific example, when the power conversion device 1 is used in a first country, a 200 VAC system power supply is connected to the power conversion device 1 (boost converter B1 ), and the power conversion device 1 is started.

[0100] In this case, in the present embodiment, the boost converter B1 sets the target boost voltage to 380 V and outputs a DC voltage of 380 V, and the current resonance converter B2 operates in the full-bridge mode (full-bridge operation).

[0101] When the power conversion device 1 is used in the second country, a 400 VAC power supply is connected to the power conversion device 1 (boost converter B1 ), and the power conversion device 1 is started.

[0102] In this case, in the present embodiment, the boost converter B1 sets the target boost voltage to 760 V and outputs a DC voltage of 760 V, and the current resonance converter B2 operates in the half-bridge mode (half-bridge operation).

[0103] Here, in the present embodiment, after startup, the power conversion device 1 operates while maintaining the set operation mode without changing the set operation mode until a predetermined reset occurs.

[0104] The reset occurs when, for example, the input voltage (or input power, etc.) to the power conversion device 1 (boost converter B1) is below a specified value for a period of time exceeding a specified value. The period of time exceeding a specified value is set in advance, for example, such as when a circuit breaker is disconnected, to set the time for the reset to occur.

[0105] That is, for example, a reset occurs when the input voltage to the power conversion device 1 (boost converter B1) is substantially cut off due to the opening of a circuit breaker of a power source supplying the input voltage to the power conversion device 1 (boost converter B1) or the like.

[0106] Furthermore, the power conversion device 1 may be configured not to perform a reset process when a momentary power outage occurs.

[0107] Here, in this embodiment, the input voltage levels of the 200VAC system and the 400VAC system are exemplified, but other input voltage levels may be used as the plurality of input voltage levels. In addition, in this embodiment, the output voltage level of the boost converter B1 is exemplified as either 380V or 760V, but other output voltage levels may be used as the output voltage level.

[0108] For example, in this embodiment, a voltage ratio of 1:2 such as 200V and 400V or 380V and 760V is used, but as other examples, such a ratio may deviate to the extent that there is no practical obstacle, for example, a ratio of 0.9:2 or 1:2.1 may be used.

[0109] In addition, in this embodiment, the case where the input voltage to the power conversion device 1 (boost converter B1) can have two or more input voltage levels depending on the country is exemplified, but it can also be applied to the case where the input voltage can have two or more input voltage levels due to reasons other than the country.

[0110] In the present embodiment, a case where the input voltage to the power conversion device 1 (boost converter B1 ) can have two input voltage levels is described, but the present embodiment is also applicable to a case where the input voltage can have three or more input voltage levels.

[0111] Hereinafter, the power conversion device 1 according to the present embodiment will be described in further detail.

[0112] <Explanation of related technologies>

[0113] First, refer to Figure 2A to Figure 2C , Figure 3 and Figure 4A to Figure 4B , and explain the related technologies.

[0114] Figure 2A This is a diagram showing an example of switching loss of a switching element (MOSFET Q1 in this example).

[0115] exist Figure 2A In the example of FIG. 1 , the input voltage of the boost converter is 400V alternating current (AC), and the output voltage of the boost converter is 760V direct current (DC).

[0116] exist Figure 2A In the graph shown, the horizontal axis represents time, and the vertical axis represents the level of each indicator.

[0117] In this curve graph, as various indicators, the characteristics of the drain-source voltage 3011 (Vds) of the switching element (MOSFETQ1 in this example), the characteristics of the drain current 3012 (Id) of the switching element (MOSFETQ1 in this example), and the characteristics of the switching loss 3013 generated by them are shown.

[0118] Figure 2B This is a diagram showing another example of the switching loss of the switching element (MOSFET Q1 in this example).

[0119] exist Figure 2B In the example of FIG. 1 , the input voltage of the boost converter is an alternating current (AC) of 200 V, and the output voltage of the boost converter is a direct current (DC) of 760 V.

[0120] exist Figure 2B In the graph shown, the horizontal axis represents time, and the vertical axis represents the level of each indicator.

[0121] In this graph, as indicators, the characteristics of the drain-source voltage 3021 (Vds) of the switching element (MOSFETQ1 in this example), the characteristics of the drain current 3022 (Id) of the switching element, and the characteristics of the switching loss 3023 generated by them are shown.

[0122] Figure 2C This is a diagram showing another example of the switching loss of the switching element (MOSFET Q1 in this example).

[0123] exist Figure 2C In the example of FIG. 1 , the input voltage of the boost converter is 200V alternating current (AC), and the output voltage of the boost converter is 380V direct current (DC).

[0124] exist Figure 2C In the graph shown, the horizontal axis represents time, and the vertical axis represents the level of each indicator.

[0125] In this graph, as indicators, the characteristics of the drain-source voltage 3031 (Vds) of the switching element (MOSFETQ1 in this example), the characteristics of the drain current 3032 (Id) of the switching element, and the characteristics of the switching loss 3033 generated by them are shown.

[0126] Here, the output voltage of the boost converter needs to be set higher than the upper limit of the input range. However, if the voltage is boosted from a low input voltage in the case of a wide input, the switching loss increases and the efficiency decreases.

[0127] For example, when the input voltage is an AC voltage of 200 V to 480 V, the boost voltage ( Vc1 ) of the boost converter is approximately 760 V ( Vc1 > 480×1.1×1.412=747 V).

[0128] Since the switching loss of the semiconductor is proportional to (voltage × current), the switching loss Psw is proportional to (output voltage Vc1 × input current Iin). In the case of hard switching, the switching loss when the input voltage is 200V is twice the switching loss when the input voltage is 400V (for example, refer to Figure 2A and Figure 2B ).

[0129] Figure 3 This is a diagram showing an example of switching loss and conduction loss of a switching element (MOSFET Q1 in this example).

[0130] Figure 3 It shows the degree of switching loss 3111 and conduction loss 3112 when the input voltage is 400V AC and the output voltage is 760V DC, the degree of switching loss 3121 and conduction loss 3122 when the input voltage is 200V AC and the output voltage is 380V DC, and the degree of switching loss 3131 and conduction loss 3132 when the input voltage is 200V AC and the output voltage is 760V DC.

[0131] In addition, the unit of the switching loss and the conduction loss is, for example, watt.

[0132] Figure 4A This is a diagram showing an example of the relationship between the operating frequency and the output voltage ratio of the current resonance converter.

[0133] Figure 4A The figure shows the case where the coupling coefficient k of the transformer is k=0.75.

[0134] exist Figure 4AIn the graph shown, the horizontal axis represents the operating frequency (Normalized Frequency) of the current resonance converter, and the vertical axis represents the output voltage ratio (output voltage Vo / input voltage Vi) of the current resonance converter. Here, the input voltage Vi to the current resonance converter is equal to the output voltage Vc1 from the previous step-up converter.

[0135] exist Figure 4A 3 shows the relationship between the operating frequency and the output voltage ratio of the current resonance type converter in the case of a low load and a characteristic 3211 in the case of a high load. Figure 4A In the example, the resonant frequency is set to 1.0.

[0136] Figure 4B This is a diagram showing another example of the relationship between the operating frequency and the output voltage ratio of the current resonance converter.

[0137] Figure 4B The figure shows the case where the coupling coefficient k of the transformer is k=0.95.

[0138] exist Figure 4B In the graph shown, the horizontal axis represents the operating frequency (Normalized Frequency) of the current resonance type converter, and the vertical axis represents the output voltage ratio (output voltage Vo / input voltage Vi) of the current resonance type converter.

[0139] exist Figure 4B 3 shows the relationship between the operating frequency and the output voltage ratio of the current resonance type converter in the case of a low load and a characteristic 3222 in the case of a high load. Figure 4B In the example, the resonant frequency is set to 1.0.

[0140] Here, if the output voltage of the boost converter is set to two stages, 380V and 760V, the subsequent current resonance converter (DC-DC converter) operates with this range as the input voltage, but generally, if the input of the current resonance converter is widened, the efficiency decreases.

[0141] like Figure 4A As shown in the example, when the coupling coefficient k of the transformer is small, the output voltage ratio can be changed by more than 2 times by changing the frequency, so even if the voltage of the boost converter changes by 2 times, the output voltage of the current resonance converter can be kept constant. However, if the coupling coefficient k is small, the excitation current of the transformer increases relatively, and the efficiency decreases.

[0142] On the other hand, Figure 4BAs shown in the example, when the coupling coefficient k of the transformer is large, the excitation current can be reduced and high efficiency can be achieved, but the voltage adjustment range is narrow and cannot cope with the output voltage range of the boost converter. However, even when the coupling coefficient k is large, if the operating frequency is fixed at the resonant frequency (near the low load characteristic 3221 and the high load characteristic 3222 contact), there is almost no load change.

[0143] <Example of Control of Current Resonance Converter in the Present Embodiment>

[0144] Next, refer to Figure 5A to Figure 5E , an example of control of the current resonance converter B2 in this embodiment is described.

[0145] In the power conversion device 1 of the present embodiment, in a system where the input voltage of the boost converter B1 is an AC system of 400 V (400 VAC system), the boost voltage (output voltage) is set to 760 V. On the other hand, in the power conversion device 1 of the present embodiment, in a system where the input voltage of the boost converter B1 is an AC system of 200 V (200 VAC system), the boost voltage (output voltage) is set to 380 V (=760 V×1 / 2).

[0146] Thus, in the power conversion device 1 of the present embodiment, the switching losses in the 200VAC system and the 400VAC system can be made substantially equal (for example, see Figure 2A and Figure 2C ).

[0147] In addition, in the power conversion device 1 of the present embodiment, MOSFETQ11~Q14 is controlled so that when the input voltage of the boost converter B1 is at a low level (Vin_L), the primary side of the current resonant converter B2 is set to a full-bridge structure, and when the input voltage of the boost converter B1 is at a high level (Vin_H), the primary side of the current resonant converter B2 is set to a half-bridge structure.

[0148] Here, when the input voltage (Vboost) of the current resonance converter B2 is high, by operating the primary side in half-bridge operation, the amplitude of the primary side voltage of the transformer TR1 becomes equal to the amplitude of the full-bridge operation at low level, and the output voltage is also equal.

[0149] The input voltage (Vboost) is controlled by the boost converter B1 so that it is fixed even if the AC input voltage (Vac) or the load current varies. Therefore, for example, the output voltage (Vo) of the current resonant converter B2 can be stabilized without using feedback control by fixing the operating frequency at the resonant frequency (or near it).

[0150] Figure 5AThis is a diagram showing an example of the relationship between the AC input voltage and the output voltage for explaining the switching between the full-bridge operation and the half-bridge operation according to the embodiment.

[0151] exist Figure 5A In the graph shown, the horizontal axis represents the AC input voltage (Vac) of the boost converter B1 , and the vertical axis represents the output voltage of the boost converter B1 (=the input voltage of the current resonance converter B2 ).

[0152] exist Figure 5A , as the voltage range when the AC input voltage (Vac) is at the low level (Vin_L), a voltage range from a minimum value Vin_L_min to a maximum value Vin_L_max is shown.

[0153] In addition, Figure 5A , as the voltage range when the AC input voltage (Vac) is at the high level (Vin_H), a voltage range from a minimum value Vin_H_min to a maximum value Vin_H_max is shown.

[0154] Here, Vin_L_max<Vin_H_min.

[0155] In the voltage range of the AC input voltage (Vac) from the minimum value Vin_L_min of the low level to the maximum value Vin_L_max, the output voltage of the boost converter B1 becomes the output voltage (V_L) of the low level.

[0156] On the other hand, within the voltage range of the AC input voltage (Vac) from the minimum value Vin_H_min of the high level to the maximum value Vin_H_max, the output voltage of the boost converter B1 becomes a high-level output voltage (V_H).

[0157] In the present embodiment, a threshold voltage Vth is set between the low-level output voltage (V_L) and the high-level output voltage (V_H).

[0158] In addition, the threshold voltage Vth may be, for example, a midpoint (or the vicinity thereof) between the low-level output voltage (V_L) and the high-level output voltage (V_H), or may be another point.

[0159] Figure 5B It is a diagram showing a state of a half-bridge operation in the current resonance converter according to the embodiment.

[0160] Figure 5C It is a diagram showing a state of a full-bridge operation in the current resonance converter according to the embodiment.

[0161] exist Figure 5B and Figure 5C, for convenience of explanation, an example of control of the current resonance type converter B2 is shown.

[0162] In this embodiment, when the input voltage of the current resonance converter B2 is at a high level (V_H), Figure 5B As shown, the current resonance type converter B2 is controlled to perform half-bridge operation. In addition, in this embodiment, the high level (V_H) is 760 V. Specifically, the control circuit 111 (operation mode setting circuit 133 and current resonance type converter drive circuit 134) controls to make MOSFETQ13 into an open state and MOSFETQ14 into an on state, and performs half-bridge operation through MOSFETQ11 and MOSFETQ12.

[0163] On the other hand, in this embodiment, when the input voltage of the current resonance converter B2 is at a low level (V_L), Figure 5C As shown, the current resonance converter B2 is controlled to perform full bridge operation. In addition, in this embodiment, the low level (V_L) is 380V.

[0164] Specifically, the control circuit 111 (operation mode setting circuit 133 and current resonance converter drive circuit 134 ) controls the four MOSFETs Q11 to Q14 so as to perform a full-bridge operation.

[0165] Figure 5D 1 is a diagram showing an example of a voltage applied to the primary side of the transformer TR1 during the half-bridge operation according to the embodiment.

[0166] exist Figure 5D In Figure 5B The voltage applied to the primary side of the transformer TR1 during the half-bridge operation (in the present embodiment, the voltage 3311 applied to both ends of the inductor 51, the primary winding 52, and the capacitor 53) is an example of the voltage Vx.

[0167] Specifically, the voltage applied to the primary side becomes a periodic pulse-shaped voltage 3311 .

[0168] The voltage 3311 has two levels, 0 V and +760 V (Vboost), and has a pulse level of ±380 V, based on the midpoint of these voltage ranges (1 / 2×Vboost).

[0169] Figure 5E 1 is a diagram showing an example of a voltage applied to the primary side of the transformer TR1 during the full-bridge operation according to the embodiment.

[0170] Figure 5E Indicated in Figure 5CThe voltage applied to the primary side of the transformer TR1 during the full-bridge operation (in the present embodiment, the voltage 3312 applied to both ends of the inductor 51, the primary winding 52, and the capacitor 53) is an example of the voltage Vx.

[0171] Specifically, the voltage applied to the primary side becomes a periodic pulse-shaped voltage 3312 .

[0172] The voltage 3312 has a level of two values, -380 V (-Vboost) and +380 V (+Vboost), which become pulses of ±380 V levels.

[0173] <Drive signal switching circuit>

[0174] Reference Figure 6A to Figure 6B , the drive signal switching circuit is described.

[0175] Fig. 6A 1 is a diagram showing an example of a drive signal switching circuit 201 according to an embodiment.

[0176] The driving signal switching circuit 201 switches the operation mode of the current resonance converter B2 between the full-bridge mode and the half-bridge mode.

[0177] In the present embodiment, the control circuit 111 (for example, the current resonance type converter driving circuit 134 ) includes a driving signal switching circuit 201 .

[0178] The drive signal switching circuit 201 includes a NOT circuit 211 , a NOR circuit 212 , and an OR circuit 213 .

[0179] Here, the control circuit 111 includes an oscillator (not shown), and the output from the oscillator will be described as an oscillator output OSC.

[0180] In addition, the control circuit 111 generates an input voltage determination signal Vsel indicating either the 200VAC system or the 400VAC system as a determination result of the input voltage.

[0181] In this embodiment, the control circuit 111 sets the input voltage determination signal Vsel to a low-level signal when the input voltage detected by the input voltage detection circuit 151 is at a low level, and sets the input voltage determination signal Vsel to a high-level signal when the input voltage detected by the input voltage detection circuit 151 is at a high level.

[0182] In the drive signal switching circuit 201 , the transmitter output OSC is set as a switch drive signal (control voltage applied to the gate) of the MOSFET Q11 .

[0183] In addition, the transmitter output OSC is input to the input end of the NOT circuit 211, and the output from the output end of the NOT circuit 211 (a signal after the oscillator output OSC is inverted) is set as a switch drive signal (control voltage applied to the gate) of the MOSFETQ12.

[0184] In addition, the oscillator output OSC and the input voltage determination signal Vsel are respectively input to two input terminals of the NOR circuit 212, and the output from the output terminal of the NOR circuit 212 is set as a switch drive signal (control voltage applied to the gate) of the MOSFET Q13.

[0185] In addition, the oscillator output OSC and the input voltage determination signal Vsel are respectively input to two input terminals of the OR circuit 213, and the output from the output terminal of the OR circuit 213 is set as a switch drive signal (control voltage applied to the gate) of the MOSFET Q14.

[0186] Figure 6B 1 is a diagram showing an example of input and output signals of the drive signal switching circuit 201 according to the embodiment.

[0187] exist Figure 6B In the graph shown, the horizontal axis represents time, and the vertical axis represents the voltage level of each signal.

[0188] As input signals of the drive signal switching circuit 201, a signal 3511 corresponding to the oscillator output OSC and a signal 3512 corresponding to the input voltage determination signal Vsel are shown.

[0189] Furthermore, as output signals of the drive signal switching circuit 201 , a signal 3521 of a control voltage of the MOSFET Q11 , a signal 3522 of a control voltage of the MOSFET Q12 , a signal 3523 of a control voltage of the MOSFET Q13 , and a signal 3524 of a control voltage of the MOSFET Q14 are indicated.

[0190] Through these signals, switching between full-bridge operation and half-bridge operation is achieved in the current resonance converter B2.

[0191] also, Fig. 6A and Figure 6B The circuit and signal shown are just examples, and any other configuration may be used as a configuration for switching between the full-bridge operation and the half-bridge operation in the current resonance converter B2.

[0192] <Example of switching timing of the operation mode of the current resonance converter>

[0193] In the present embodiment, at the moment when the primary side of the current resonance type converter B2 is switched between the full-bridge structure and the half-bridge structure, it is considered that the output voltage fluctuates and an overcurrent and an overvoltage are generated in the element.

[0194] Therefore, in the present embodiment, the switching of the bridge operation is not performed during the operation of the power conversion device 1. For example, in the power conversion device 1, control is performed so that when the input voltage is lower than the reference value (threshold) at startup, the full-bridge operation mode is selected, and when the input voltage is higher than the reference value (threshold) at startup, the half-bridge operation mode is selected. Moreover, in the power conversion device 1, after the selection is made, the selected operation mode is fixed even if the input voltage varies.

[0195] Furthermore, in the power conversion device 1, when the reset operation by input cutoff is performed, the operation mode is reselected at the time of startup. That is, in the power conversion device 1, when the reset operation is performed, the operation mode is changed.

[0196] <Example of operation of power conversion device>

[0197] Reference Figure 1 , showing an example of the operation of the power conversion device 1 according to the present embodiment.

[0198] The boost converter B1 boosts the input voltage Vin input to the input terminal (a terminal connected to the AC power supply 11 in the present embodiment) to obtain an output voltage (voltage Vc1), charges an output capacitor (capacitor 34) connected to the output terminal (a terminal connected to the current resonance converter B2 in the present embodiment), and outputs the output voltage.

[0199] Here, in the present embodiment, the boost converter B1 has an AC input configuration, but as another example, it may have a DC input configuration.

[0200] In the present embodiment, a PFC (Power Factor Correction) converter that performs power factor correction control (PFC control) is used as the boost converter B1 , but the PFC function does not necessarily have to be included.

[0201] Output voltage detection circuit 152 detects the voltage of the output capacitor (capacitor 34 ) Boost converter control circuit 131 controls boost converter B1 based on the voltage detected by output voltage detection circuit 152 .

[0202] The input voltage detection circuit 151 detects a voltage corresponding to the input voltage (Vin) to the boost converter B1.

[0203] The operation mode setting circuit 133 sets the output voltage of the boost converter B1 to a low level (low level mode) or a high level (high level mode) according to the value of the voltage detected by the input voltage detection circuit 151 .

[0204] The control circuit 111 (current resonance type converter driving circuit 134 ) controls the full-bridge current resonance type converter B2 according to the level (mode) set by the operation mode setting circuit 133 .

[0205] Specifically, the control circuit 111 (current resonance type converter driving circuit 134) is controlled so as to operate in the full-bridge mode when the level is low, and is controlled so as to operate in the half-bridge mode when the level is high.

[0206] In the present embodiment, the set level is determined at an arbitrary timing after the input voltage is input, and the operation mode of the current resonance converter is maintained until the set level is reset.

[0207] <Example of operation of a current resonance converter at a fixed frequency>

[0208] The current resonance converter B2 may be configured to operate at a fixed frequency.

[0209] Specifically, the switching elements (MOSFETs Q11 to Q14) operating in the full-bridge mode or half-bridge mode are configured to operate at a fixed frequency rather than by feedback control of the output voltage output from the secondary side circuit (control of the voltage on the secondary side of the feedback transformer TR1).

[0210] The fixed frequency is, for example, a frequency near the resonance frequency (for example, see Figure 4B ).

[0211] In a configuration in which the current resonance converter B2 operates at a fixed frequency, a control circuit for changing the frequency can be eliminated, and the control circuit can be simplified.

[0212] Furthermore, even if the frequency is variable, if the control point is constant, the operation is the same as that at a fixed frequency.

[0213] Thus, the current resonance type converter B2 operates at 380 V when the input is at a low level (380 V), and operates at 760 V when the input is at a high level (760 V).

[0214] As described above, in the power conversion system A1 of the present embodiment, in the configuration including the current resonance converter B2 at the subsequent stage of the boost converter B1 in the power conversion device 1, high efficiency can be achieved even when the input voltage of the boost converter B1 can be of two input voltage levels.

[0215] Here, in this embodiment, the case where the secondary side circuit of the current resonance type converter B2 includes a rectifier circuit using two diodes 91 and 92 is shown, but other rectifier circuits may be included. In addition, in this embodiment, the case where the resistor 12 is included on the output side of the current resonance type converter B2 is exemplified, but other arbitrary circuits may be connected instead of the resistor 12.

[0216] (Second embodiment)

[0217] A second embodiment will be described.

[0218] [Power conversion system]

[0219] Figure 7 1 is a diagram showing a configuration example of a circuit of a power conversion system A11 according to a second embodiment. Figure 1 The same components as those shown are denoted by the same reference numerals and described, and detailed description is omitted.

[0220] The power conversion system A11 of the present embodiment includes a power conversion device 301 , an AC power source 11 , and a resistor 12 .

[0221] The power conversion device 301 includes a boost converter B11 and a current resonance converter B2 .

[0222] exist Figure 7 In the example, omit Figure 1 A diagram of the control circuit 111 is shown.

[0223] The configuration and operation of the power conversion system A11 of this embodiment are similar to those of the first embodiment. Figure 1 The structure and operation of the power conversion system A1 shown are different in that the boost converter B11 includes an inrush current limiting circuit 310 .

[0224] The inrush current limiting circuit 310 includes a resistor 311 and a switch 312 .

[0225] A resistor 311 and a switch 312 are connected in parallel between one terminal of the AC power source 11 and the diode bridge 31 .

[0226] In addition, in this embodiment, for the sake of convenience, the inrush current limiting circuit 310 provided in the preceding stage of the boost converter B11 is regarded as a circuit portion of the boost converter B11 for explanation, but it can also be understood that the inrush current limiting circuit 310 is a circuit different from the boost converter B11, for example.

[0227] <Example of the operation of the inrush current limiting circuit>

[0228] The boost converter B11 includes an inrush current limiting circuit 310 in a path for charging the output capacitor (capacitor 34).

[0229] The control circuit 111 (for example, the boost converter control circuit 131) controls the switch 312 of the inrush current limiting circuit 310 to be turned OFF at startup, and the inrush current is suppressed by the resistor 311. Thereafter, at a predetermined timing when the inrush current ends, the control circuit 111 (for example, the boost converter control circuit 131) controls the switch 312 of the inrush current limiting circuit 310 to be turned ON.

[0230] In the present embodiment, after the inrush current at startup ends and the inrush current limitation of the inrush current limiting circuit 310 is released (the switch 312 is turned on), the control circuit 111 (for example, the boost converter control circuit 131) determines the target boost voltage of the boost converter B11 based on the value of the voltage detected by the input voltage detection circuit 151. This determination process may be, for example, a process of selecting a target boost voltage from a plurality of target boost voltages (380V or 760V in the present embodiment).

[0231] Here, in the present embodiment, the startup time refers to the startup (rising) time of the AC power source 11 .

[0232] <Example of boost voltage selection processing>

[0233] Figure 8 It is a diagram showing a processing flow of an example of the boost voltage selection processing according to the second embodiment.

[0234] The control circuit 111 performs processing to select a boost voltage based on the detection result of the input voltage. Figure 8 In the graph shown, the horizontal axis represents time, and the vertical axis represents the voltage Vc1 applied to both ends of the capacitor 34 .

[0235] The horizontal axis of the graph represents time t0 to time t3.

[0236] The vertical axis of the graph shows the low-level input voltage Vin_L, the low-level output voltage V_L, the threshold voltage Vth, the high-level input voltage Vin_H, and the high-level output voltage V_H for the boost converter B11.

[0237] Here, the range of the low-level input voltage Vin_L is represented by the range of Vin_L_min to Vin_L_max, and the midpoint of the range is represented by Vin_L_typ.

[0238] The range of the high-level input voltage Vin_H is represented by Vin_H_min to Vin_H_max, and the midpoint of the range is represented by Vin_H_typ.

[0239] exist Figure 8 In the example, characteristic 3411 when the input voltage is Vin_L_min, characteristic 3412 when the input voltage is Vin_L_typ, characteristic 3413 when the input voltage is Vin_L_max, characteristic 3431 when the input voltage is Vin_H_min, characteristic 3432 when the input voltage is Vin_H_typ, and characteristic 3433 when the input voltage is Vin_H_max are shown.

[0240] The threshold voltage Vth is a level that serves as a reference for switching the operation mode.

[0241] In the present embodiment, it is set to (Vin_L_max<Vth<Vin_H_min).

[0242] At time t0 , in the power conversion device 301 , the input voltage is turned on.

[0243] First, in the power conversion device 301 , the switch 312 of the inrush current limiting circuit 310 is opened, and the boost converter B11 charges (charges) the output capacitor (capacitor 34 ) via the inrush current prevention resistor (resistor 311 ).

[0244] Thereafter, at time t1 , in the power conversion device 301 , the switch 312 connected in parallel with the surge current prevention resistor (resistor 311 ) is turned on (the switching element is turned on).

[0245] At this time, the voltage of the output capacitor (capacitor 34) further increases by a voltage amount corresponding to the difference between the voltage of the surge current prevention resistor (resistor 311) and the voltage applied when the switch 312 is in the on state.

[0246] Then, at time t2, the power conversion device 301 detects and determines the input voltage. That is, in the power conversion device 301, when it is determined that the input voltage Vin (in this embodiment, the voltage Vc1 applied to both ends of the capacitor 34) is lower than the threshold voltage Vth serving as the reference value, control is performed to set the target value of the boosted voltage to the low-level output voltage V_L, and the full-bridge operation is performed using the current resonance converter B2.

[0247] On the other hand, in the power conversion device 301, when it is determined that the input voltage Vin (in the present embodiment, the voltage Vc1 applied to both ends of the capacitor 34) is higher than the threshold voltage Vth which is a reference value, control is performed to set the target value of the boost voltage to a high-level output voltage V_H, and half-bridge operation is performed using the current resonant converter B2.

[0248] In addition, in the present embodiment, it is set that there is no situation where the input voltage Vin (in the present embodiment, the voltage Vc1 applied to both ends of the capacitor 34) is equal to the threshold voltage Vth which becomes the reference value, but when this situation exists, it can also be set to shift to a specified operating mode (in the present embodiment, either the full-bridge mode or the half-bridge mode).

[0249] Thereafter, at time t3, the power conversion device 301 controls the boost circuit (boost converter B11) to start operating and output the set target boost voltage value, and starts operating the current resonance circuit (current resonance converter B2) according to the set target boost voltage value.

[0250] Thus, in the power conversion device 301 of the present embodiment, the output capacitor (capacitor 34) is charged (charged) from time t0 to time t1, the voltage corresponding to the input voltage of the boost converter B11 is detected at time t2 after time t1 (in the present embodiment, the voltage Vc1 applied to both ends of the capacitor 34), and the system to be adapted (200VAC system and 400VAC system) is switched at time t3.

[0251] As described above, in the power conversion system A11 of the present embodiment, in the power conversion device 301, in a structure including a current resonance converter B2 at the subsequent stage of the boost converter B11, high efficiency can be achieved even when the input voltage of the boost converter B11 can be of two input voltage levels.

[0252] (Third embodiment)

[0253] A third embodiment will be described.

[0254] [Power conversion system]

[0255] Fig.9A It is a diagram showing a configuration example of a circuit of a power conversion system A21 according to the third embodiment.

[0256] Here, in this embodiment, for the sake of convenience of explanation, Figure 7 The same components as those shown are denoted by the same reference numerals and described, and detailed description is omitted.

[0257] The power conversion system A21 of the present embodiment includes a power conversion device 401 , an AC power source 11 , and a resistor 12 .

[0258] The power conversion device 401 includes a boost converter B11 and a current resonance converter B12.

[0259] exist Fig.9A In the example, omit Figure 1 A diagram of the control circuit 111 is shown.

[0260] The configuration and operation of the power conversion system A21 of this embodiment are roughly the same as those of the second embodiment. Figure 7 The structure and operation of the power conversion system A11 shown are different in that the three operation modes are switched. Also, the structure and operation of the secondary side of the current resonance type converter B12 are different.

[0261] The current resonance converter B12 includes a secondary winding 411 , an inductor 431 , a capacitor 432 , four diodes 451 to 454 as rectifying elements, a switch 471 , and a capacitor 472 on the secondary side.

[0262] Here, the switch 471 may be formed using, for example, a semiconductor switch element, or may be formed using a mechanical switch (for example, a relay).

[0263] In addition, the primary winding 52 and the secondary winding 411 constitute a transformer TR11.

[0264] In addition, in this embodiment, a full-bridge rectifier circuit is included.

[0265] <Circuit connection relationship>

[0266] The connection relationship of the secondary side circuit of the current resonance type converter B12 will be described.

[0267] One end of the secondary winding 411 is connected to one end of the inductor 431 .

[0268] The other end of the secondary winding 411 is connected to one end of the capacitor 432 .

[0269] The other end of the inductor 431 , the anode of the diode 451 , and the cathode of the diode 452 are connected.

[0270] The other end of the capacitor 432 , the anode of the diode 453 , the cathode of the diode 454 , and one end of the switch 471 are connected.

[0271] The cathode of the diode 451 , the cathode of the diode 453 , one end of the capacitor 472 , and one end of the resistor 12 are connected.

[0272] An anode of the diode 452 , an anode of the diode 454 , the other end of the switch 471 , the other end of the capacitor 472 , and the other end of the resistor 12 are connected.

[0273] In this way, in the secondary side circuit of the current resonance converter B12 , the rectifier circuit includes a bridge arm formed by connecting the diode 451 and the diode 452 in series, and a bridge arm formed by connecting the diode 453 and the diode 454 in series.

[0274] The two bridge arms are connected in parallel.

[0275] Both ends of the secondary winding 411 are connected to two connection points, namely, a connection point between the diode 451 and the diode 452 and a connection point between the diode 453 and the diode 454 , via the inductor 431 and the capacitor 432 .

[0276] The control circuit 111 controls the on and off switching of the switch 471 .

[0277] The control circuit 111 can switch the rectifier circuit to a voltage doubler rectifier circuit by short-circuiting any one of the four diodes 451 to 454 (the diode 454 in the present embodiment) using the switch 471 (ie, turning on the switch 471 ).

[0278] <Example of CLLC type resonant circuit>

[0279] exist Fig.9A In the example, the current resonance type converter B12 is a CLLC type.

[0280] The CLLC resonance circuit in the current resonance type converter B12 is constituted by the capacitor 53 and the inductor 51 of the primary side circuit, and the inductor 431 and the capacitor 432 of the secondary side circuit.

[0281] In this way, the input end of the rectifier circuit and both ends of the secondary winding 411 are connected via the resonant inductor (inductor 431 ) and the resonant capacitor (capacitor 432 ).

[0282] <Example of using leakage inductance>

[0283] For example, one or both of the resonant inductor (inductor 51 ) of the primary side circuit of the transformer TR11 and the resonant inductor (inductor 431 ) of the secondary side circuit of the transformer TR11 may be the leakage inductance of the transformer TR11 .

[0284] <Work Examples>

[0285] Fig. 9B It is a diagram of a table 5011 showing an example of the relationship among the input voltage, the output voltage of the boost converter B11, and the operation mode of the current resonance type converter B12 according to the third embodiment.

[0286] In this embodiment, three operation modes can be switched. In this embodiment, the operation mode setting circuit 133 sets one of the three operation modes.

[0287] In the present embodiment, the three operating modes include an operating mode corresponding to a 100VAC system, an operating mode corresponding to a 200VAC system, and an operating mode corresponding to a 400VAC system.

[0288] In this embodiment, when the input voltage to the power conversion device 401 (boost converter B11) is 100-120VAC (100VAC), the output voltage of the boost converter B11 is 190VDC, the primary side of the current resonant converter B12 is controlled to perform full-bridge operation, and the secondary side of the current resonant converter B12 is controlled to perform voltage doubler rectification.

[0289] In addition, in this embodiment, when the input voltage to the power conversion device 401 (boost converter B11) is 200-240VAC (200VAC system), the output voltage of the boost converter B11 is 380VDC, the primary side of the current resonant converter B12 is controlled to perform full-bridge operation, and the secondary side of the current resonant converter B12 is controlled to perform full-bridge rectification.

[0290] In addition, in this embodiment, when the input voltage to the power conversion device 401 (boost converter B11) is 400-480VAC (400VAC system), the output voltage of the boost converter B11 is 760VDC, the primary side of the current resonant converter B12 is controlled to perform half-bridge operation, and the secondary side of the current resonant converter B12 is controlled to perform full-bridge rectification operation.

[0291] Thus, in the power conversion device 401 of the present embodiment, when the voltage detected by the input voltage detection circuit 151 (the voltage corresponding to the input voltage at startup) is lower than the specified voltage Vth1, the primary side of the current resonance type converter B12 is controlled to the full-bridge mode, and the rectifier circuit on the secondary side operates as a voltage doubling rectifier circuit by short-circuiting the switch 471.

[0292] In addition, in the power conversion device 401 of the present embodiment, when the voltage detected by the input voltage detection circuit 151 (the voltage corresponding to the input voltage at startup) is higher than the specified voltage Vth1 and lower than the specified voltage Vth2, the primary side of the current resonance type converter B12 is controlled to the full-bridge mode, and the rectifier circuit on the secondary side is not short-circuited by the switch 471 and operates as a full-bridge rectifier circuit.

[0293] In addition, in the power conversion device 401 of the present embodiment, when the voltage detected by the input voltage detection circuit 151 (the voltage corresponding to the input voltage at startup) is higher than the specified voltage Vth2, the primary side of the current resonance type converter B12 is controlled to a half-bridge mode, and the rectifier circuit on the secondary side is not short-circuited by the switch 471 and operates as a full-bridge rectifier circuit.

[0294] In addition, when the voltage detected by the input voltage detection circuit 151 (the voltage corresponding to the input voltage at startup) is equal to the specified voltage Vth1, for example, it can be configured to perform the same control as when the voltage is lower than the specified voltage Vth1, or it can be configured to perform the same control as when the voltage is higher than the specified voltage Vth1.

[0295] In addition, when the voltage detected by the input voltage detection circuit 151 (the voltage corresponding to the input voltage at startup) is equal to the specified voltage Vth2, for example, it can be configured to perform the same control as when the voltage is lower than the specified voltage Vth2, or it can be configured to perform the same control as when the voltage is higher than the specified voltage Vth2.

[0296] As described above, in the power conversion system A21 of the present embodiment, in the power conversion device 401, in a structure including a current resonant converter B12 at the subsequent stage of the boost converter B11, high efficiency can be achieved even when the input voltage of the boost converter B11 can be at more than two input voltage levels.

[0297] (Fourth embodiment)

[0298] A fourth embodiment will be described.

[0299] [Power conversion system]

[0300] Fig.10 It is a diagram showing a configuration example of a circuit of a power conversion system A101 according to the fourth embodiment.

[0301] The power conversion system A101 includes a power conversion device 601 , a three-phase AC power supply unit 611 , and a resistor 612 .

[0302] The power conversion device 601 includes a boost converter B101 , a current resonance converter B102 , and a control circuit 111 a .

[0303] The current resonance converter B102 is connected to the subsequent stage of the boost converter B101.

[0304] In this embodiment, a case where the input voltage of the boost converter B101 is a three-phase AC is shown.

[0305] Here, briefly speaking, the structure and operation of the power conversion system A101 of this embodiment are different from those of the power conversion system A11 of the second embodiment in that three-phase AC is input to the power conversion device 601 , and the other points are the same.

[0306] The control circuit 111a includes, for example, Figure 1 Therefore, in this embodiment, regarding the control circuit 111a, Figure 1 The control circuit 111 has the same functions as shown, and its illustration and detailed description are omitted.

[0307] In addition, in this embodiment, the AC power supply unit 611 and the resistor 612 are shown as external circuits of the power conversion device 601, but as another example, a structure in which one or both of the AC power supply unit 611 and the resistor 612 are internal circuits of the power conversion device 601 can also be used.

[0308] For example, when both the AC power supply unit 611 and the resistor 612 are circuits inside the power conversion device 601 , the power conversion system A101 of the present embodiment is equal to the power conversion device 601 .

[0309] The AC power source unit 611 is a power source that outputs a three-phase AC power source, and is composed of a combination of three single-phase AC power sources 611 a , 611 b , and 611 c .

[0310] The boost converter B101 includes three inrush current limiting circuits 630a, 630b, and 630c and three inductors 651a, 651b, and 651c corresponding to the three phases, respectively.

[0311] In addition, the boost converter B101 includes six MOSFETs Q101 to Q106 and a capacitor 652 .

[0312] The inrush current limiting circuit 630a is composed of a resistor 631a and a switch 632a connected in parallel.

[0313] The inrush current limiting circuit 630b is composed of a resistor 631b and a switch 632b connected in parallel.

[0314] The inrush current limiting circuit 630c is composed of a resistor 631c and a switch 632c connected in parallel.

[0315] In addition, in this embodiment, for the sake of convenience, the inrush current limiting circuits 630a~630c provided in the front stage of the boost converter B101 are regarded as the circuit part of the boost converter B101 for explanation, but it can also be understood that the inrush current limiting circuits 630a~630c are different from the boost converter B101, for example.

[0316] The first phase terminal of the AC power supply unit 611 is connected to the source of the MOSFET Q101 and the drain of the MOSFET Q102 via the inrush current limiting circuit 630 a and the inductor 651 a .

[0317] The second phase terminal of the AC power supply unit 611 is connected to the source of the MOSFET Q103 and the drain of the MOSFET Q104 via the inrush current limiting circuit 630 b and the inductor 651 b .

[0318] The third-phase terminal of the AC power supply unit 611 is connected to the source of the MOSFET Q105 and the drain of the MOSFET Q106 via the inrush current limiting circuit 630 c and the inductor 651 c .

[0319] The drain of the MOSFET Q101 , the drain of the MOSFET Q103 , the drain of the MOSFET Q105 , and one end of the capacitor 652 are connected.

[0320] The source of the MOSFET Q102 , the source of the MOSFET Q104 , the source of the MOSFET Q106 , and the other end of the capacitor 652 are connected.

[0321] The current resonance converter B102 includes four MOSFETs Q111 to Q114 , an inductor 671 , a primary winding 672 , a capacitor 673 , secondary windings 711 and 712 , two diodes 731 and 732 , and a capacitor 733 .

[0322] Here, the primary winding 672 and the secondary windings 711 and 712 constitute a transformer TR101.

[0323] In this embodiment, the secondary windings 711 and 712 are divided into two parts by a center tap method relative to the center tap point, and for ease of description, they are respectively referred to as the secondary winding 711 and the secondary winding 712. The secondary winding 711 and the secondary winding 712 may also be integrated.

[0324] The internal circuit structure of the current resonance converter B102 is similar to Figure 7 The current resonance converter B2 shown has the same internal circuit structure.

[0325] In addition, the connection relationship between the capacitor 652 and the resistor 612 of the boost converter B101 and the current resonance converter B102 is the same as that in Figure 7 The connection relationship of the boost converter B11 shown is the same as that of the current resonance converter B2 connected between the capacitor 34 and the resistor 12 .

[0326] The control circuit 111a detects the output voltage (voltage applied to both ends of the capacitor 652) of the boost converter B101, and controls the control voltage applied to the gates of the six MOSFETs Q101 to Q106 in accordance with the three-phase AC based on the detected voltage.

[0327] In addition, the control circuit 111 a controls switches 632 a , 632 b , and 632 c of three inrush current limiting circuits 630 a , 630 b , and 630 c .

[0328] The control circuit 111 a detects a voltage corresponding to the input voltage, and sets the operation mode (full-bridge mode or half-bridge mode) of the current resonance converter B102 based on the detected voltage.

[0329] Then, the control circuit 111 a controls the control voltage applied to the gates of the MOSFETs Q111 to Q114 of the current resonance type converter B102 according to the set operation mode.

[0330] As described above, in the power conversion system A101 of this embodiment, in the power conversion device 601, in a structure including a current resonant converter B102 at the subsequent stage of the boost converter B101, high efficiency can be achieved even when the input voltage of the boost converter B101 can be two input voltage levels.

[0331] (Fifth embodiment)

[0332] A fifth embodiment will be described.

[0333] [Power conversion system]

[0334] Fig.11 It is a diagram showing a configuration example of a circuit of a power conversion system A111 according to the fifth embodiment.

[0335] Here, in this embodiment, for the sake of convenience of explanation, Fig.10 The same components as those shown are denoted by the same reference numerals and described, and detailed description is omitted.

[0336] The power conversion system A111 of the present embodiment includes a power conversion device 801 , an AC power supply unit 611 , and a resistor 612 .

[0337] The power conversion device 801 includes a boost converter B101 and a current resonance converter B112 .

[0338] exist Fig.11 In the example, omit Fig.10 A schematic diagram of the control circuit 111a is shown.

[0339] The configuration and operation of the power conversion system A111 of this embodiment are roughly the same as those of the fourth embodiment. Fig.10 Compared with the structure and operation of the power conversion system A101 shown, the structure and operation of the secondary side of the current resonance type converter B112 are different.

[0340] The current resonance type converter B112 includes a secondary winding 811 , an inductor 831 , a capacitor 832 , four diodes 851 to 854 as rectifying elements, and a capacitor 833 on the secondary side.

[0341] Here, the primary winding 672 and the secondary winding 811 constitute a transformer TR111.

[0342] In addition, in this embodiment, a full-bridge rectifier circuit is included.

[0343] <Circuit connection relationship>

[0344] The connection relationship of the secondary side circuit of the current resonance type converter B112 will be described.

[0345] One end of the secondary winding 811 is connected to one end of the inductor 831 .

[0346] The other end of the secondary winding 811 is connected to one end of the capacitor 832 .

[0347] The other end of the inductor 831 , the anode of the diode 851 , and the cathode of the diode 852 are connected.

[0348] The other end of the capacitor 832 , the anode of the diode 853 , and the cathode of the diode 854 are connected.

[0349] The cathode of the diode 851 , the cathode of the diode 853 , one end of the capacitor 833 , and one end of the resistor 612 are connected.

[0350] The anode of the diode 852 , the anode of the diode 854 , the other end of the capacitor 833 , and the other end of the resistor 612 are connected.

[0351] In this way, in the secondary side circuit of the current resonance converter B112, the rectifier circuit includes a bridge arm formed by connecting the diode 851 and the diode 852 in series, and a bridge arm formed by connecting the diode 853 and the diode 854 in series.

[0352] The two bridge arms are connected in parallel.

[0353] Both ends of the secondary winding 811 are connected to two connection points, namely, a connection point between a diode 851 and a diode 852 and a connection point between a diode 853 and a diode 854 , via an inductor 831 and a capacitor 832 .

[0354] <Example of CLLC resonant circuit>

[0355] exist Fig.11 In the example, the current resonance type converter B112 is a CLLC type.

[0356] The CLLC resonance circuit in the current resonance type converter B112 is constituted by the capacitor 673 and the inductor 671 of the primary side circuit, and the inductor 831 and the capacitor 832 of the secondary side circuit.

[0357] In this way, the input end of the rectifier circuit and both ends of the secondary winding 811 are connected via the resonant inductor (inductor 831) and the resonant capacitor (capacitor 832).

[0358] <Example of using leakage inductance>

[0359] For example, one or both of the resonant inductor (inductor 671 ) of the primary side circuit of the transformer TR111 and the resonant inductor (inductor 831 ) of the secondary side circuit of the transformer TR111 may be the leakage inductance of the transformer TR111 .

[0360] As described above, in the power conversion system A111 of the present embodiment, in the power conversion device 801, in a structure including a current resonant converter B112 at the subsequent stage of the boost converter B101, high efficiency can be achieved even when the input voltage of the boost converter B101 can be two input voltage levels.

[0361] (Sixth Implementation Method)

[0362] A sixth embodiment will be described.

[0363] [Power conversion system]

[0364] Fig.12 It is a diagram showing a configuration example of a circuit of a power conversion system A211 according to the sixth embodiment.

[0365] Here, in this embodiment, for the sake of convenience of explanation, Fig.11 The same components as those shown are denoted by the same reference numerals and described, and detailed description is omitted.

[0366] The power conversion system A211 of the present embodiment includes a power conversion device 901 , an AC power supply unit 611 , and a resistor 612 .

[0367] The power conversion device 901 includes a boost converter B101 and a current resonance converter B212 .

[0368] exist Fig.12 In the example, omit Fig.10A schematic diagram of the control circuit 111a is shown.

[0369] The configuration and operation of the power conversion system A211 of this embodiment are roughly the same as those of the fifth embodiment. Fig.11 Compared with the structure and operation of the power conversion system A111 shown, the structure and operation of the secondary side of the current resonance type converter B212 are different.

[0370] In the power conversion system A211 of this embodiment, in general, instead of the fifth embodiment Fig.11 The power conversion system A111 shown includes four diodes 851 to 854 and four MOSFETs 911 to 914 .

[0371] These four MOSFETs 911 to 914 constitute a rectifier circuit.

[0372] In the present embodiment, the control circuit 111 a has a function of controlling the control voltage applied to the gates of the four MOSFETs 911 to 914 .

[0373] As described above, in the power conversion system A211 of the present embodiment, in the power conversion device 901, in a structure including a current resonant converter B212 at the subsequent stage of the boost converter B101, high efficiency can be achieved even when the input voltage of the boost converter B101 can be two input voltage levels.

[0374] (About the above implementation methods)

[0375] In addition, the program for realizing the function of any component in any device described above can also be recorded in a computer-readable recording medium, so that the computer system reads the program and executes it. In addition, the "computer system" mentioned here includes hardware such as an operating system or peripheral devices. In addition, "computer-readable recording medium" refers to removable media such as floppy disks, optical magnetic disks, ROMs, CD (Compact Disc)-ROM (Read Only Memory), and storage devices such as hard disks built into the computer system. Furthermore, "computer-readable recording medium" includes a medium that keeps the program for a certain period of time, such as a volatile memory inside a server or a computer system as a client in the case of sending a program via a network such as the Internet or a communication line such as a telephone line. For example, the volatile memory can be a RAM (Random Access Memory). The recording medium can be, for example, a non-temporary recording medium.

[0376] In addition, the above-mentioned program can also be transmitted from a computer system storing the program in a storage device, etc. to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the "transmission medium" for transmitting the program refers to a medium having the function of transmitting information, such as a network such as the Internet or a communication line such as a telephone line.

[0377] In addition, the above program can also be used to implement a part of the above functions. Furthermore, the above program can also be a program that can implement the above functions by combining with a program already recorded in the computer system, that is, a so-called differential file. The differential file can also be called a differential program.

[0378] In addition, the functions of any structural parts in any of the devices described above can also be implemented by a processor. For example, each process in the embodiment can also be implemented by a processor that works based on information such as a program and a computer-readable recording medium that stores information such as a program. Here, the processor can, for example, implement the functions of each part through separate hardware, or it can also implement the functions of each part through integrated hardware. For example, the processor may include hardware, and the hardware may include at least one of a circuit for processing digital signals and a circuit for processing analog signals. For example, the processor may also be configured using one or more circuit devices or one or more circuit elements mounted on a circuit substrate, or both. As a circuit device, an IC (Integrated Circuit) or the like can be used, and as a circuit element, a resistor or a capacitor or the like can also be used.

[0379] Here, the processor may be, for example, a CPU. However, the processor is not limited to the CPU, and various processors such as a GPU (Graphics Processing Unit) or a DSP (Digital Signal Processor) may also be used. In addition, the processor may be, for example, a hardware circuit based on an ASIC (Application Specific Integrated Circuit). In addition, the processor may be, for example, composed of a plurality of CPUs, or may be composed of a plurality of ASIC hardware circuits. In addition, the processor may be, for example, composed of a combination of a plurality of CPUs and a plurality of ASIC hardware circuits. In addition, the processor may also include, for example, one or more of an amplifier circuit or a filter circuit that processes analog signals.

[0380] As mentioned above, although the embodiment of the present invention is described in detail with reference to the drawings, the specific structure is not limited to this embodiment, and also includes the design etc. within the scope which does not deviate from the summary of the present invention.

[0381] [Note]

[0382] [Structural Example 1] to [Structural Example 8] are shown below.

[0383] [Structural Example 1]

[0384] A power conversion device, comprising a boost converter, a current resonance converter connected to a subsequent stage of the boost converter, and a control circuit.

[0385] The boost converter boosts an input voltage to obtain an output voltage, charges a first output capacitor with the output voltage, and outputs the output voltage.

[0386] The control circuit controls the boost converter based on a voltage detected by an output voltage detection circuit that detects a voltage of the first output capacitor.

[0387] The control circuit sets the output voltage of the boost converter to a first output voltage level or a second output voltage level based on a voltage detected by an input voltage detection circuit that detects a voltage corresponding to the input voltage, and operates the current resonance type converter in a full-bridge mode when the first output voltage level is set, and operates the current resonance type converter in a half-bridge mode when the second output voltage level is set.

[0388] The output voltage detection circuit and the input voltage detection circuit are a common circuit or separate circuits,

[0389] The first output voltage level or the second output voltage level is set at a predetermined timing after the input voltage is input, and the operation mode is maintained until the setting of the first output voltage level or the second output voltage level is reset.

[0390] Here, in Figure 1 In the example of the power conversion device 1, the boost converter B1, the current resonance converter B2, the control circuit 111, the capacitor 34, the output voltage detection circuit 152, and the input voltage detection circuit 151 are respectively an example of a boost converter, a current resonance converter, a control circuit, a first output capacitor, an output voltage detection circuit, and an input voltage detection circuit.

[0391] In addition, Figure 1 In the power conversion device 1 of the example, 380 V and 760 V are used as examples of the first output voltage level and the second output voltage level.

[0392] exist Figure 7 In the power conversion device 301 of the example, boost converter B11 is an example of a boost converter.

[0393] exist Fig.9A In the power conversion device 401 of the example, the current resonance type converter B12 is an example of a current resonance type converter.

[0394] exist Fig.10 In the example of the power conversion device 601, the boost converter B101, the current resonance converter B102, the control circuit 111a, and the capacitor 652 are examples of the boost converter, the current resonance converter, the control circuit, and the first output capacitor, respectively. Fig.10 In the example of FIG. 1 , the control circuit 111 a has the same function as the output voltage detection circuit 152 and the same function as the input voltage detection circuit 151 .

[0395] exist Fig.11 In the power conversion device 801 of the example, the current resonance type converter B112 is an example of a current resonance type converter.

[0396] exist Fig.12 In the power conversion device 901 of the example, the current resonance type converter B212 is an example of a current resonance type converter.

[0397] [Structural Example 2]

[0398] The power conversion device according to [Configuration Example 1], wherein the current resonance converter includes:

[0399] A first bridge arm in which a first switching element and a second switching element are connected in series;

[0400] A second bridge arm formed by connecting a third switching element and a fourth switching element in series;

[0401] A transformer having a primary winding and a secondary winding;

[0402] 1st resonant inductor;

[0403] a first resonant capacitor; and

[0404] First rectifier circuit,

[0405] In the primary side circuit of the transformer, the first bridge arm and the second bridge arm are connected in parallel, and both ends of the primary winding are connected to two connection points, namely, a connection point between the first switching element and the second switching element and a connection point between the third switching element and the fourth switching element, via the first resonant inductor and the first resonant capacitor.

[0406] In the secondary side circuit of the transformer, both ends of the secondary winding are connected to the input end of the first rectifier circuit.

[0407] In the set operation mode, the first switching element, the second switching element, the third switching element, and the fourth switching element are not controlled by feedback of the output from the secondary side circuit, but are operated at a fixed frequency.

[0408] Here, in Figure 1 , Figure 7 , Fig.9A In the power conversion devices 1, 301, and 401 of the examples, MOSFETs Q11 to Q14 are examples of first to fourth switching elements, the inductor 51 is an example of a first resonant inductor, and the capacitor 53 is an example of a first resonant capacitor.

[0409] exist Figure 1 , Figure 7 In the example of the power conversion device 1 and the power conversion device 301, the transformer TR1 is an example of a transformer, the primary winding 52 is an example of a primary winding, the secondary winding 71 and the secondary winding 72 are examples of secondary windings, and the rectifier circuit formed by the diode 91 and the diode 92 is an example of a first rectifier circuit.

[0410] exist Fig.9A In the power conversion device 401 of the example, the transformer TR11 is an example of a transformer, the primary winding 52 is an example of a primary winding, the secondary winding 411 is an example of a secondary winding, and the rectifier circuit composed of diodes 451 to 454 is an example of a first rectifier circuit.

[0411] exist Fig.10 , Fig.11 , Fig.12 In the power conversion devices 601 , 801 , and 901 of the examples, MOSFETs Q111 to Q114 are examples of first to fourth switching elements, the inductor 671 is an example of a first resonant inductor, and the capacitor 673 is an example of a first resonant capacitor.

[0412] exist Fig.10 In the power conversion device 601 of the example, the transformer TR101 is an example of a transformer, the primary winding 672 is an example of a primary winding, the secondary windings 711 and 712 are examples of secondary windings, and the rectifier circuit composed of diodes 731 and 732 is an example of a first rectifier circuit.

[0413] exist Fig.11 In the power conversion device 801 of the example, the transformer TR111 is an example of a transformer, the primary winding 672 is an example of a primary winding, the secondary winding 811 is an example of a secondary winding, and the rectifier circuit composed of diodes 851 to 854 is an example of a first rectifier circuit.

[0414] exist Fig.12In the power conversion device 901 of the example, the transformer TR111 is an example of a transformer, the primary winding 672 is an example of a primary winding, the secondary winding 811 is an example of a secondary winding, and the rectifier circuit composed of MOSFETs 911 to 914 is an example of a first rectifier circuit.

[0415] [Structural Example 3]

[0416] According to the power conversion device described in [Configuration Example 2], wherein the first rectifier circuit is a full-bridge rectifier circuit,

[0417] In the secondary side circuit, an input end of the first rectifier circuit and both ends of the secondary winding are connected via a second resonant inductor and a second resonant capacitor.

[0418] Here, in Fig.9A In the power conversion device 401 of the example, the inductor 431 is an example of a second resonant inductor, and the capacitor 432 is an example of a second resonant capacitor.

[0419] exist Fig.11 , Fig.12 In the power conversion devices 801 and 901 of the examples, the inductor 831 is an example of a first resonant inductor, and the capacitor 832 is an example of a first resonant capacitor.

[0420] [Structural Example 4]

[0421] In the power conversion device described in [Configuration Example 3], leakage inductance of the transformer is used as the first resonant inductor and the second resonant inductor.

[0422] [Structural Example 5]

[0423] The power conversion device according to any one of [Configuration Example 1] to [Configuration Example 4], wherein an inrush current limiting circuit is provided in a path for charging the first output capacitor,

[0424] The control circuit determines a target boost voltage of the boost converter based on a voltage detected by the input voltage detection circuit after the inrush current at startup ends and the inrush current limitation by the inrush current limiting circuit is released.

[0425] Here, in Figure 7 , Fig.9A In the power conversion devices 301 and 401 of the examples, the inrush current limiting circuit 310 is an example of an inrush current limiting circuit.

[0426] exist Fig.10 , Fig.11 , Fig.12In the power conversion devices 601, 801, and 901 of the examples, the three-phase inrush current limiting circuits 630a to 630c are examples of inrush current limiting circuits.

[0427] [Structural Example 6]

[0428] The power conversion device according to any one of [Configuration Example 1] to [Configuration Example 5], wherein the input voltage is a single-phase AC or a three-phase AC voltage,

[0429] The boost converter is a PFC converter that performs power factor correction control.

[0430] Here, in Figure 1 , Figure 7 , Fig.9A In the power conversion device 1 , the power conversion device 301 , and the power conversion device 401 of the examples, the input voltage is a single-phase AC voltage.

[0431] exist Fig.10 , Fig.11 , Fig.12 In the power conversion devices 601, 801, and 901 of the examples, the input voltage is a three-phase AC voltage.

[0432] [Structural Example 7]

[0433] The power conversion device according to [Configuration Example 3] or [Configuration Example 4], wherein the first rectifier circuit includes:

[0434] a third bridge arm in which the first rectifying element and the second rectifying element are connected in series; and

[0435] The fourth bridge arm in which the third rectifying element and the fourth rectifying element are connected in series,

[0436] The third bridge arm is connected in parallel with the fourth bridge arm, and both ends of the secondary winding are connected to two connection points of a connection point between the first rectifying element and the second rectifying element and a connection point between the third rectifying element and the fourth rectifying element.

[0437] By short-circuiting any one of the first rectifier element, the second rectifier element, the third rectifier element, or the fourth rectifier element using the first switch, the first rectifier circuit can be operated as a voltage doubler rectifier circuit.

[0438] The first switch is a semiconductor switch element or a relay.

[0439] exist Fig.9A In the power conversion device 401 of the example, the diodes 451 to 454 are examples of the first to fourth rectifying elements, and the switch 471 is an example of the first switch.

[0440] exist Fig.9A In the example of FIG. 4 , the diode 454 (fourth switching element) is the target rectifying element to be short-circuited.

[0441] [Structural Example 8]

[0442] The power conversion device according to [Configuration Example 7], wherein the control circuit includes:

[0443] When the voltage detected by the input voltage detection circuit is lower than the first predetermined voltage, the current resonance converter is operated in the operation mode of the full-bridge mode, and the first rectifier circuit is operated as the voltage doubler rectifier circuit by short-circuiting the target rectifier element using the first switch.

[0444] When the voltage detected by the input voltage detection circuit is higher than the first predetermined voltage and lower than the second predetermined voltage, the current resonance type converter is controlled in the operation mode of the full-bridge mode so that the target rectifying element is not short-circuited by the first switch and the first rectifying circuit is operated as a full-bridge rectifying circuit.

[0445] When the voltage detected by the input voltage detection circuit is higher than the second specified voltage, the current resonance converter is operated in the operating mode of the half-bridge mode, the object rectifying element is not short-circuited by the first switch, and the first rectifying circuit is operated as a full-bridge rectifying circuit.

[0446] exist Fig.9A In the power conversion device 401 of the example, the predetermined voltage Vth1 and the predetermined voltage Vth2 are examples of the first predetermined voltage and the second predetermined voltage, respectively.

[0447] Description of Reference Numerals

[0448] 1. 301, 401, 601, 801, 901…power conversion device

[0449] 11. 611a~611c…AC power supply

[0450] 12, 311, 612, 631a~631c…resistance

[0451] 31…Diode bridge

[0452] 32, 51, 431, 651a~651c, 671, 831…Inductors

[0453] 33, 91, 92, 731, 732, 851~854... diodes

[0454] 34, 53, 93, 432, 472, 652, 673, 733, 832, 833…capacitors

[0455] 52…Primary winding

[0456] 71, 72, 411, 672, 711, 712, 811… Secondary winding

[0457] 111, 111a…control circuit

[0458] 131…Boost converter control circuit

[0459] 132…Voltage detection circuit

[0460] 133…Working mode setting circuit

[0461] 134…Current resonance converter drive circuit

[0462] 151…Input voltage detection circuit

[0463] 152…Output voltage detection circuit

[0464] 211…NOT circuit

[0465] 212…NOR circuit

[0466] 213…OR circuit

[0467] 310, 630a~630c…Surge current limiting circuit

[0468] 312…Switch

[0469] 451~454…Diode

[0470] 471, 632a~632c…switch

[0471] 611…AC Power Supply

[0472] 911~914, Q1, Q11~Q14, Q101~Q106, Q111~Q114…MOSFET

[0473] 3011, 3021, 3031, 3311, 3312... voltage

[0474] 3012, 3022, 3032…Drain current

[0475] 3013, 3023, 3033, 3111, 3121, 3131…Switching loss

[0476] 3112, 3122, 3132…conduction loss

[0477] 3211, 3212, 3221, 3222, 3411 to 3413, 3431 to 3433… Characteristics

[0478] 3511~3512、3521~3524…Signal

[0479] 5011…Table

[0480] A1, A11, A21, A101, A111, A211…Power conversion system

[0481] B1, B11, B101…Boost Converter

[0482] B2, B12, B102, B112, B212…Current resonance converter

[0483] TR1, TR11, TR101, TR111…transformers.

Claims

1. A power conversion device, characterized in that: The invention comprises a boost converter, a current resonance converter connected to the subsequent stage of the boost converter, and a control circuit. The boost converter boosts an input voltage to obtain an output voltage, charges a first output capacitor with the output voltage, and outputs the output voltage. The control circuit controls the boost converter based on a voltage detected by an output voltage detection circuit that detects a voltage of the first output capacitor. The control circuit sets the output voltage of the boost converter to a first output voltage level or a second output voltage level based on a voltage detected by an input voltage detection circuit that detects a voltage corresponding to the input voltage, and operates the current resonance type converter in a full-bridge mode when the first output voltage level is set, and operates the current resonance type converter in a half-bridge mode when the second output voltage level is set. The output voltage detection circuit and the input voltage detection circuit are a common circuit or separate circuits, The first output voltage level or the second output voltage level is set at a predetermined timing after the input voltage is input, and the operation mode is maintained until the setting of the first output voltage level or the second output voltage level is reset.

2. The power conversion device according to claim 1, characterized in that: The current resonance converter comprises: A first bridge arm in which a first switching element and a second switching element are connected in series; A second bridge arm in which a third switching element and a fourth switching element are connected in series; A transformer having a primary winding and a secondary winding; 1st resonant inductor; a first resonant capacitor; and First rectifier circuit, In the primary side circuit of the transformer, the first bridge arm and the second bridge arm are connected in parallel, and both ends of the primary winding are connected to two connection points, namely, a connection point between the first switching element and the second switching element and a connection point between the third switching element and the fourth switching element, via the first resonant inductor and the first resonant capacitor. In the secondary side circuit of the transformer, both ends of the secondary winding are connected to the input end of the first rectifier circuit. In the set operation mode, the first switching element, the second switching element, the third switching element, and the fourth switching element are not operated by control in which the output from the secondary-side circuit is fed back, but are operated at a fixed frequency.

3. The power conversion device according to claim 2, characterized in that: The first rectifier circuit is a full-bridge rectifier circuit. In the secondary side circuit, an input end of the first rectifier circuit and both ends of the secondary winding are connected via a second resonant inductor and a second resonant capacitor.

4. The power conversion device according to claim 3, characterized in that: The leakage inductance of the transformer is used as the first resonant inductor and the second resonant inductor.

5. The power conversion device according to any one of claims 1 to 4, characterized in that: An inrush current limiting circuit is provided in a path for charging the first output capacitor. The control circuit determines a target boost voltage of the boost converter based on a voltage detected by the input voltage detection circuit after the inrush current at startup ends and the inrush current limitation by the inrush current limiting circuit is released.

6. The power conversion device according to any one of claims 1 to 4, characterized in that: The input voltage is a single-phase AC or three-phase AC voltage. The boost converter is a PFC converter that performs power factor correction control.

7. The power conversion device according to claim 3 or 4, characterized in that: The first rectifier circuit comprises: a third bridge arm in which the first rectifying element and the second rectifying element are connected in series; and The fourth bridge arm in which the third rectifying element and the fourth rectifying element are connected in series, The third bridge arm and the fourth bridge arm are connected in parallel, and both ends of the secondary winding are connected to two connection points, namely, a connection point between the first rectifying element and the second rectifying element and a connection point between the third rectifying element and the fourth rectifying element. By short-circuiting any one of the first rectifier element, the second rectifier element, the third rectifier element, or the fourth rectifier element using the first switch, the first rectifier circuit can be operated as a voltage doubler rectifier circuit. The first switch is a semiconductor switch element or a relay.

8. The power conversion device according to claim 7, characterized in that: The control circuit comprises: When the voltage detected by the input voltage detection circuit is lower than the first predetermined voltage, the current resonance converter is operated in the operation mode of the full-bridge mode, and the first rectifier circuit is operated as the voltage doubler rectifier circuit by short-circuiting the target rectifier element using the first switch. When the voltage detected by the input voltage detection circuit is higher than the first predetermined voltage and lower than the second predetermined voltage, the current resonance type converter is controlled in the operation mode of the full-bridge mode so that the target rectifying element is not short-circuited by the first switch and the first rectifying circuit is operated as a full-bridge rectifying circuit. When the voltage detected by the input voltage detection circuit is higher than the second specified voltage, the current resonance converter is operated in the operating mode of the half-bridge mode, the object rectifying element is not short-circuited by the first switch, and the first rectifying circuit is operated as a full-bridge rectifying circuit.

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