Converter device

Abstract

To provide a converter device capable of achieving high efficiency while maintaining a high power factor.SOLUTION: A converter device 100 includes a first rectifier 2, a half bridge inverter 3, an input inductor Li, a transformer Tr1, a second rectifier 4, an inductor L1, and a control device 5. The control device 5 controls at least the half bridge inverter 3. The control device 5 adjusts a DC bus voltage Vdc or an output voltage Vo by controlling on time of one of a first switching element Q1 and a second switching element Q2 based on the DC bus voltage Vdc or the output voltage Vo. The control device 5 sets a mode of an inductor current ILi to a current critical mode by controlling the on time of the other of the first switching element Q1 and the second switching element Q2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a converter device. [Background technology]

[0002] Patent Document 1 discloses a switching power supply device (converter device) that receives DC power as input and outputs AC power.

[0003] The switching power supply device disclosed in Patent Document 1 includes a series circuit having a PFC inductor, a first rectifier element, and a first switch element, and a series circuit having a PFC inductor, a second rectifier element, and a second switch element, which are connected to an AC power supply. The first switch element and the second switch element form a series switch circuit, and an energy storage capacitor is connected in parallel to the series switch circuit. One end of a series resonant circuit having a primary winding of a transformer is connected to a connection point between the first switch element and the second switch element. Furthermore, a rectifying and smoothing circuit is connected to the secondary winding of the transformer.

[0004] During the positive half cycle of the AC input voltage, the first switch element operates as the main switch element, the second switch element operates as the synchronous rectifier element, and the energy storage capacitor operates as the smoothing capacitor. During the negative half cycle of the AC input voltage, the second switch element operates as the main switch element, the first switch element operates as the synchronous rectifier element, and the energy storage capacitor operates as the smoothing capacitor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2013 / 099918 Summary of the Invention [Problem to be solved by the invention]

[0006] In an isolated converter device equipped with a transformer, it is desirable to achieve high efficiency while maintaining a high power factor.

[0007] An object of the present disclosure is to provide a converter device capable of achieving high efficiency while maintaining a high power factor. [Means for solving the problem]

[0008] A converter device according to an embodiment of the present disclosure includes a first rectifier, a half-bridge inverter, an input inductor, a transformer, a second rectifier, an inductor, and a control device. The first rectifier has a first series circuit in which a first rectifier element and a second rectifier element are connected in series, and a first AC output end of an AC power supply is connected to a connection point between the first rectifier element and the second rectifier element. The half-bridge inverter has a second series circuit of a first switching element and a second switching element, and a third series circuit of a first capacitor and a second capacitor, and the second series circuit and the third series circuit are connected in parallel to the first series circuit, and a second AC output end of the AC power supply is connected to a connection point between the first switching element and the second switching element. The input inductor is connected between the AC power supply and the first rectifier or the half-bridge inverter. The transformer includes a primary winding and a secondary winding, and the primary winding is connected between a first output terminal between the first switching element and the second switching element and a second output terminal between the first capacitor and the second capacitor. The second rectifier is connected to the secondary winding of the transformer and outputs an output voltage obtained by rectifying a secondary voltage generated in the secondary winding. The inductor acts on an electric path between the first output terminal or the second output terminal and the primary winding. The control device controls at least the half-bridge inverter. The control device alternately turns on the first switching element and the second switching element. The control device adjusts the DC bus voltage or the output voltage by controlling an on-time of one of the first switching element and the second switching element based on a DC bus voltage that is a voltage across the third series circuit or the output voltage. The control device sets a mode of an inductor current flowing through the input inductor to a current critical mode by controlling an on-time of the other of the first switching element and the second switching element. Effect of the Invention

[0009] The present disclosure has an effect of achieving high efficiency while maintaining a high power factor. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a circuit diagram showing a converter device according to the first embodiment. [Diagram 2] FIG. 2 is a timing chart for explaining the operation of the converter device when the polarity of the input voltage is positive. [Diagram 3] 3A and 3B are diagrams illustrating the operation of the converter device when the polarity of the input voltage is positive. [Figure 4] FIG. 4 is an operational waveform diagram of the converter device. [Diagram 5] FIG. 5 is a timing chart for explaining the operation of the converter device when the polarity of the input voltage is negative. [Figure 6] 6A and 6B are diagrams illustrating the operation of the converter device when the polarity of the input voltage is negative. [Figure 7] FIG. 7 is a block diagram showing a control device provided in the converter device. [Figure 8] FIG. 8 is a waveform diagram showing the operation of each part of the converter device according to the above embodiment. [Figure 9] FIG. 9 is a waveform diagram showing the operation of each part of the converter device according to the first embodiment. [Figure 10] FIG. 10 is a block diagram showing a control device of the first modified example of the above embodiment. [Figure 11] FIG. 11 is a circuit diagram showing a converter device according to a second modification of the above embodiment. [Figure 12] FIG. 12 is a circuit diagram showing a converter device according to the second embodiment. [Figure 13] FIG. 13 is a block diagram showing a control device provided in the converter device. [Figure 14] FIG. 14 is a timing chart for explaining the operation of the control device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The following embodiments relate generally to a converter device, and more particularly to an isolated converter device including a transformer.

[0012] The following embodiment is merely an example of the present disclosure. The present disclosure is not limited to the following embodiment, and various modifications are possible depending on the design, etc., as long as the effects of the present disclosure can be achieved.

[0013] (Embodiment 1) (1) Overview of the converter device A converter device 100 of this embodiment is an insulating AC / DC converter having the configuration shown in FIG. 1 and converts AC power into DC power.

[0014] The converter device 100 includes a first rectifier 2, a half-bridge inverter 3, an input inductor Li, a transformer Tr1, a second rectifier 4, an inductor L1, and a control device 5.

[0015] The first rectifier 2 has a first series circuit 21 in which a first rectifier element E1 and a second rectifier element E2 are connected in series, and a first AC output terminal 81 of the AC power supply 8 is connected to a connection point 22 between the first rectifier element E1 and the second rectifier element E2.

[0016] The half-bridge inverter 3 has a second series circuit 31 including a first switching element Q1 and a second switching element Q2, and a third series circuit 32 including a first capacitor C1 and a second capacitor C2. The second series circuit 31 and the third series circuit 32 are connected in parallel to the first series circuit 21. A second AC output terminal 82 of the AC power supply 8 is connected to a connection point 33 between the first switching element Q1 and the second switching element Q2.

[0017] The input inductor Li is connected between the AC power supply 8 and the first rectifier 2 or the half-bridge inverter 3 .

[0018] The transformer Tr1 includes a primary winding N1 and a secondary winding N2. The primary winding N1 is connected between a first output terminal 34 between the first switching element Q1 and the second switching element Q2 and a second output terminal 35 between the first capacitor C1 and the second capacitor C2.

[0019] The second rectifier 4 is connected to the secondary winding N2 of the transformer Tr1, and outputs an output voltage Vo obtained by rectifying the secondary voltage V2 generated in the secondary winding N2.

[0020] The inductor L1 acts on the electric path between the primary winding N1 and the first output port 34 or the second output port 35. The inductor L1 may be either an inductor element separate from the transformer Tr1 and connected between the first output port 34 or the second output port 35 and the primary winding N1, or a leakage inductance connected to the primary winding N1 in an equivalent circuit of the transformer Tr1.

[0021] The control device 5 controls at least the half-bridge inverter 3. The control device 5 alternately turns on the first switching element Q1 and the second switching element Q2. The control device 5 adjusts the DC bus voltage Vdc or the output voltage Vo by controlling the on-time of one of the first switching element Q1 and the second switching element Q2 based on the DC bus voltage Vdc or the output voltage Vo, which is the voltage across the third series circuit 32. The control device 5 sets the mode of the inductor current ILi flowing through the input inductor Li to a current critical mode by controlling the on-time of the other of the first switching element Q1 and the second switching element Q2.

[0022] By setting the mode of the inductor current ILi to the critical current mode, the converter device 100 can reduce the effective value of the input current Ii supplied from the AC power source 8 to the converter device 100. As a result, the converter device 100 can achieve high efficiency while maintaining a high power factor.

[0023] (2)Details As shown in FIG. 1, the converter device 100 includes a filter section 1, a first rectifier 2, a half-bridge inverter 3, a second rectifier 4, a control device 5, a pair of input terminals 11, 12, a pair of output terminals 13, 14, an input inductor Li, a transformer Tr1, an inductor L1, and an output capacitor Co.

[0024] (2.1) Input and output terminals The input terminals 11 and 12 are connected to an AC power supply 8. The AC power supply 8 is, for example, a 100V or 200V commercial power supply, has a first AC output terminal 81 and a second AC output terminal 82, and generates an AC input voltage Vi between the first AC output terminal 81 and the second AC output terminal 82. The input terminal 11 is connected to the first AC output terminal 81, and the input terminal 12 is connected to the second AC output terminal 82. That is, the AC input voltage Vi is applied between the input terminals 11 and 12.

[0025] The converter device 100 converts an AC input voltage Vi into a DC output voltage Vo, and outputs the DC output voltage Vo from output terminals 13, 14. That is, the DC output voltage Vo is applied between the output terminals 13, 14.

[0026] The AC power supply 8 may be a power supply that utilizes renewable energy such as solar power, wind power, geothermal power, water, biomass, etc. The AC power supply 8 may also be a power supply that generates AC power from charging power of a storage battery.

[0027] (2.2) Filter section The filter unit 1 is a filter circuit having at least one of an inductor and a capacitor, and includes, for example, any of a low-pass filter, a high-pass filter, a band-pass filter, and a band-stop filter.

[0028] A pair of input ends of the filter unit 1 are connected to input terminals 11 and 12, respectively. One of a pair of output ends of the filter unit 1 is connected to a connection point 22 (described later) of the first rectifier 2. The other of the pair of output ends of the filter unit 1 is connected to a connection point 33 (described later) of the half-bridge inverter 3 via an input inductor Li.

[0029] AC power input from an AC power source 8 to input terminals 11 and 12 is supplied via a filter unit 1 to a first rectifier 2 and a half-bridge inverter 3 in the subsequent stage.

[0030] (2.3) 1st rectifier The first rectifier 2 has a first diode D1 as a first rectifying element E1, and a second diode D2 as a second rectifying element E2.

[0031] That is, the first rectifier 2 includes a first series circuit 21 in which a first diode D1 and a second diode D2 are connected in series. The cathode of the second diode D2 is connected to the anode of the first diode D1, and the first diode D1 and the second diode D2 are connected in series. The connection point between the anode of the first diode D1 and the cathode of the second diode D2 constitutes a connection point 22. In the first rectifier 2, a first AC output terminal 81 of the AC power supply 8 is connected to the connection point 22 via the input terminal 11 and the filter unit 1.

[0032] (2.4) Input inductor The input inductor Li is connected between a second AC output terminal 82 of the AC power supply 8 and a connection point 33 (described later) of the half-bridge inverter 3. More specifically, the input inductor Li has a first end and a second end. The first end of the input inductor Li is connected to the second AC output terminal 82 of the AC power supply 8 via the filter unit 1 and the input terminal 12. The second end of the input inductor Li is connected to the connection point 33 of the half-bridge inverter 3.

[0033] (2.5) Half-bridge inverter The half-bridge inverter 3 has a second series circuit 31 including a first switching element Q1 and a second switching element Q2, and a third series circuit 32 including a first capacitor C1 and a second capacitor C2. The second series circuit 31 and the third series circuit 32 are connected in parallel to the first series circuit 21 of the first rectifier 2. That is, the first series circuit 21, the second series circuit 31, and the third series circuit 32 are connected in parallel to each other. The first switching element Q1 is connected to the cathode of the first diode D1, and the second switching element Q2 is connected to the anode of the second diode D2.

[0034] In the half-bridge inverter 3, the connection point between the first switching element Q1 and the second switching element Q2 constitutes a connection point 33. The connection point 33 is connected to a second AC output terminal 82 of the AC power supply 8 via an input inductor Li, a filter unit 1, and an input terminal 12.

[0035] In the half-bridge inverter 3, each of the first switching element Q1 and the second switching element Q2 is a semiconductor switching element having a control terminal, a first main terminal, and a second main terminal. The control terminals of the first switching element Q1 and the second switching element Q2 are connected to the control device 5. The first switching element Q1 is turned on and off in response to a first switching signal S1 provided by the control device 5. The second switching element Q2 is turned on and off in response to a second switching signal S2 provided by the control device 5. The first switching element Q1 and the second switching element Q2 are, for example, a GaN-based GIT (Gate Injection Transistor). In the first switching element Q1 and the second switching element Q2, the control terminal, the first main terminal, and the second main terminal are a gate terminal, a drain terminal, and a source terminal, respectively.

[0036] The drain terminal of the first switching element Q1 is connected to the cathode of the first diode D1. The source terminal of the first switching element Q1 is connected to the drain terminal of the second switching element Q2. The source terminal of the second switching element Q2 is connected to the anode of the second diode D2.

[0037] A first end of the first capacitor C1 is connected to the drain terminal of the first switching element Q1 and the cathode of the first diode D1. A second end of the first capacitor C1 is connected to a first end of the second capacitor C2. A second end of the second capacitor C2 is connected to the source terminal of the second switching element Q2 and the anode of the second diode D2.

[0038] (2.6) Transformer The transformer Tr1 includes a primary winding N1 and a secondary winding N2. The primary winding N1 is connected between a first output terminal 34 between a first switching element Q1 and a second switching element Q2 in the half-bridge inverter 3, and a second output terminal 35 between a first capacitor and a second capacitor in the half-bridge inverter 3.

[0039] The secondary winding N2 is connected to a second rectifier 4.

[0040] In the half-bridge inverter 3, the first switching element Q1 and the second switching element Q2 are turned on and off, so that the voltage generated in the primary winding N1 becomes an alternating voltage, and the voltage generated in the secondary winding N2 also becomes an alternating voltage.

[0041] (2.7) Inductors The inductor L1 acts on an electric path between the first output terminal 34 and the primary winding N1 of the half-bridge inverter 3. That is, a first terminal of the inductor L1 is connected to the first output terminal 34, a second terminal of the inductor L1 is connected to the first terminal of the primary winding N1, and a second terminal of the primary winding N1 is connected to the second output terminal 35. In other words, a series circuit of the inductor L1 and the primary winding N1 is connected between the first output terminal 34 and the second output terminal 35.

[0042] The inductor L1 may be either an inductor element separate from the transformer Tr1, or a leakage inductance connected to the primary winding in the equivalent circuit of the transformer Tr1.

[0043] (2.8)Second rectifier The second rectifier 4 generates a DC output voltage Vo by rectifying the secondary voltage generated in the secondary winding N2. The second rectifier 4 has a first DC output terminal 41 and a second DC output terminal 42, and outputs the output voltage Vo from the first DC output terminal 41 and the second DC output terminal 42. The first DC output terminal 41 becomes a high potential of the output voltage Vo, and the second DC output terminal 42 becomes a low potential of the output voltage Vo.

[0044] The second rectifier 4 may be either an asynchronous rectifier circuit or a synchronous rectifier circuit.

[0045] The asynchronous rectifier circuit may be either a full-wave rectifier circuit in which at least four diodes are connected in a full bridge configuration, or a half-wave rectifier circuit in which at least two diodes are connected in a half bridge configuration.

[0046] The synchronous rectifier circuit has a switching element such as a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) instead of the diode of the asynchronous rectifier circuit, and the switching element is turned on and off according to the polarity of the secondary voltage generated in the secondary winding N2. The synchronous rectifier circuit may be either a synchronous full-wave rectifier circuit or a synchronous half-wave rectifier circuit. When the second rectifier 4 is a synchronous rectifier circuit, the control device 5 generates a switching signal that controls the switching element included in the synchronous rectifier circuit, and turns the switching element on and off by the switching signal.

[0047] The second rectifier 4 of this embodiment full-wave rectifies the secondary voltage generated in the secondary winding N2. The second rectifier 4 outputs the DC voltage obtained by full-wave rectifying the secondary voltage as an output voltage Vo from the first DC output terminal 41 and the second DC output terminal 42. The current output from the first DC output terminal 41 by the second rectifier 4 is defined as an output current Io.

[0048] (2.9) Output capacitor The output capacitor Co is connected between the output terminals 13 and 14. Specifically, a first end of the output capacitor Co is connected to the output terminal 13 and is also connected to a first DC output terminal 41 of the second rectifier 4. A second end of the output capacitor Co is connected to the output terminal 14 and is also connected to a second DC output terminal 42 of the second rectifier 4.

[0049] The output capacitor Co smoothes the output voltage Vo output from the first DC output terminal 41 and the second DC output terminal 42 of the second rectifier 4. The output voltage Vo is output from output terminals 13 and 14.

[0050] (2.10) Control device The control device 5 controls at least the half-bridge inverter 3. The control device 5 controls the first switching element Q1 and the second switching element Q2 of the half-bridge inverter 3. The control device 5 is configured to provide first and second switching signals (control signals) S1 to S2 to the first and second switching elements Q1 to Q2, respectively. The first and second switching signals S1 to S2 are gate voltages (gate signals) applied between the control terminals and the second main terminals of the first and second switching elements Q1 to Q2, respectively, to turn on and off the first and second switching elements Q1 to Q2. The first and second switching signals S1 to S2 are voltages whose voltage levels change between a voltage level (hereinafter also referred to as a high level) higher than the threshold voltages (gate threshold voltages) of the first and second switching elements Q1 to Q2 and a voltage level (hereinafter also referred to as a low level) lower than the threshold voltages. That is, the control device 5 can control the output voltage Vo by controlling the half-bridge inverter 3.

[0051] Furthermore, when the second rectifier 4 is a synchronous rectifier circuit, the control device 5 controls the switching element of the synchronous rectifier circuit. The control device 5 is configured to be able to provide a switching signal to the switching element of the synchronous rectifier circuit. The control device 5 is configured to be able to change the phase of the switching signal provided to the switching element of the synchronous rectifier circuit with respect to the switching signals S1 to S2. In this case, the control device 5 can control the output voltage Vo by controlling the half-bridge inverter 3 and the second rectifier 4.

[0052] 2 is a time chart when the control device 5 controls the first and second switching elements Q1 to Q2 when the polarity of the input voltage Vi is positive (the potential of the first AC output terminal 81 of the AC power source 8 is higher than the potential of the second AC output terminal 82, and the potential of the input terminal 11 is higher than the potential of the input terminal 12). FIG. 5 is a time chart when the control device 5 controls the first and second switching elements Q1 to Q2 when the polarity of the input voltage Vi is negative (the potential of the second AC output terminal 82 of the AC power source 8 is higher than the potential of the first AC output terminal 81, and the potential of the input terminal 12 is higher than the potential of the input terminal 11). FIGS. 2 and 5 show, from the top to the bottom, the waveforms of the first switching signal S1, the second switching signal S2, the inductor current ILi, and the primary AC voltage V1. The inductor current ILi is a current flowing through the input inductor Li. The primary alternating voltage V1 is the voltage between the first output terminal 34 and the second output terminal 35 when the potential of the second output terminal 35 is set as a reference potential.

[0053] The control device 5 alternately switches the first switching signal S1 between a high level and a low level, and alternately switches the second switching signal S2 between a high level and a low level. At this time, the control device 5 sets the second switching signal S2 to a low level when the first switching signal S1 is at a high level, and sets the second switching signal S2 to a high level when the first switching signal S1 is at a low level. In other words, the control device 5 alternately turns on the first and second switching elements Q1 and Q2.

[0054] As described above, the control device 5 controls the first and second switching elements Q1 and Q2, whereby the primary alternating voltage V1 is generated between the first output terminal 34 and the second output terminal 35. Specifically, the primary alternating voltage V1 is an alternating voltage that is a positive voltage when the first switching element Q1 is on and a negative voltage when the second switching element Q2 is on.

[0055] Furthermore, it is preferable to provide a dead time Td when inverting the voltage levels of the first switching signal S1 and the second switching signal S2. The dead time Td is a period during which both of the first and second switching elements Q1 and Q2 connected in series are maintained in an off state. During the dead time Td, both the first switching signal S1 and the second switching signal S2 are maintained at a low level.

[0056] In this embodiment, the control device 5 controls the first switching element Q1 and the second switching element Q2 so that the mode of the inductor current ILi, which is the current flowing through the input inductor Li, is the current critical mode.

[0057] When the polarity of the input voltage Vi is positive, the control device 5 generates the first switching signal S1 and the second switching signal S2 so as to transition as follows: first period T1-dead time Td-second period T2-dead time Td-first period T1-... as shown in FIG. 2. The first period T1 is a period in which the first switching signal S1 is at a high level and the second switching signal S2 is at a low level. The second period T2 is a period in which the first switching signal S1 is at a low level and the second switching signal S2 is at a high level. The dead time Td is a period in which the first switching signal S1 and the second switching signal S2 are at a low level. The switching period Tsw of the half-bridge inverter 3 is composed of the dead time Td-first period T1-dead time Td-second period T2.

[0058] 3A and 3B are operation explanatory diagrams for the first period T1 and the second period T2 of FIG. 2, respectively. In FIG. 3A and FIG. 3B, the current path of the inductor current ILi (see FIG. 4) is shown by a thin dashed line. In the first period T1, as shown in FIG. 3A, energy is stored in the input inductor Li by the inductor current ILi. In the second period T2, as shown in FIG. 3B, the energy of the input inductor Li is released and the inductor current ILi decreases to zero. Also, in FIG. 3A and FIG. 3B, the primary current I1 flowing through the primary winding N1 of the transformer Tr1 is shown by a thick dashed line.

[0059] Specifically, in the first period T1 in Fig. 2, the first switching element Q1 is on and the second switching element Q2 is off, so that an inductor current ILi flows through the path of the first diode D1-first switching element Q1-input inductor Li as shown in Fig. 3A. In the first period T1, the inductor current ILi increases with the passage of time from the start of the first period T1, and energy is stored in the input inductor Li. Also, in the first period T1 in Fig. 2, a primary current I1 flows through the path of the first capacitor C1-first switching element Q1-primary winding N1-first capacitor C1 as shown in Fig. 3A.

[0060] When the dead time Td has elapsed since the end of the first period T1, the voltage across the second switching element Q2 has dropped to zero volts. As a result, the second switching element Q2 is switched to zero volts at the start of the second period T2.

[0061] During the second period T2 in Fig. 2, the first switching element Q1 is off and the second switching element Q2 is on, so that an inductor current ILi flows through the path of the first diode D1-first capacitor C1-second capacitor C2-second switching element Q2-input inductor Li, as shown in Fig. 3B. At this time, the stored energy in the input inductor Li is released from the input inductor Li, and the inductor current ILi decreases to zero as time passes from the start of the second period T2. Also, during the second period T2, a primary current I1 flows through the path of the second capacitor C2-primary winding N1-second switching element Q2-second capacitor C2.

[0062] The control device 5 switches the second switching signal S2 from high level to low level at the timing when the inductor current ILi decreases and reaches zero in the second period T2, thereby setting the mode of the inductor current ILi to the current critical mode.

[0063] Then, when the inductor current ILi during the second period T2 decreases and reaches zero, after a dead time Td during which both the first and second switching elements Q1 and Q2 are maintained in the off state, the control device 5 switches the first switching signal S1 from low level to high level, thereby starting the first period T1.

[0064] When the polarity of the input voltage Vi is negative, the control device 5 generates the first switching signal S1 and the second switching signal S2 so as to transition as follows: third period T11-dead time Td-fourth period T12-dead time Td-third period T11-... as shown in FIG. 5. The third period T11 is a period in which the first switching signal S1 is at a low level and the second switching signal S2 is at a high level. The fourth period T12 is a period in which the first switching signal S1 is at a high level and the second switching signal S2 is at a low level. The dead time Td is a period in which the first switching signal S1 and the second switching signal S2 are at a low level. The switching period Tsw of the half-bridge inverter 3 is composed of the dead time Td-third period T11-dead time Td-fourth period T12.

[0065] 6A and 6B are diagrams illustrating the operation of the third period T11 and the fourth period T12 of FIG. 5, respectively. In FIGS. 6A and 6B, the current path of the inductor current ILi is shown by a thin dashed line. In the third period T11, as shown in FIG. 6A, energy is stored in the input inductor Li by the inductor current ILi. In the fourth period T12, as shown in FIG. 6B, the energy of the input inductor Li is released. In addition, in FIGS. 6A and 6B, the primary current I1 flowing through the primary winding N1 of the transformer Tr1 is shown by a thick dashed line.

[0066] Specifically, in the third period T11 in Fig. 5, the first switching element Q1 is off and the second switching element Q2 is on, so that the inductor current ILi flows through the path of the input inductor Li-second switching element Q2-second diode D2 as shown in Fig. 6A. In the third period T11, the inductor current ILi (absolute value) increases with the passage of time from the start of the third period T11, and energy is stored in the input inductor Li. Also, in the third period T11, the primary current I1 flows through the path of the second capacitor C2-primary winding N1-second switching element Q2-second capacitor C2 as shown in Fig. 6A.

[0067] When the dead time Td has elapsed since the end of the third period T11, the voltage across the first switching element Q1 has dropped to zero volts. As a result, the first switching element Q1 is switched to zero volts at the start of the fourth period T12.

[0068] In the fourth period T12 in Fig. 5, the first switching element Q1 is on and the second switching element Q2 is off, so that an inductor current ILi flows through the path of the input inductor Li-first switching element Q1-first capacitor C1-second capacitor C2-second diode D2, as shown in Fig. 6B. At this time, the stored energy in the input inductor Li is released from the input inductor Li, and the inductor current ILi (absolute value) decreases to zero as time passes from the start of the fourth period T12. Also, in the fourth period T12, a primary current I1 flows through the path of the first capacitor C1-first switching element Q1-primary winding N1-first capacitor C1.

[0069] The control device 5 switches the first switching signal S1 from high level to low level at the timing when the inductor current ILi decreases and reaches zero in the fourth period T12, thereby setting the mode of the inductor current ILi to the current critical mode.

[0070] Then, when the inductor current ILi in the fourth period T12 decreases and reaches zero, after a dead time Td during which both the first and second switching elements Q1 and Q2 are maintained in the off state, the control device 5 switches the second switching signal S2 from low level to high level, and starts the third period T11.

[0071] As described above, the control device 5 controls the first switching element Q1 and the second switching element Q2 so that the mode of the inductor current ILi is the current critical mode. Note that Fig. 4 also illustrates the waveform of the input current Ii (see Fig. 1) flowing from the AC power supply 8 to the converter device 100.

[0072] When the first switching element Q1 and the second switching element Q2 are alternately turned on, an alternating voltage is generated across the primary winding N1 by the primary alternating voltage V1. When an alternating voltage is generated across the primary winding N1, an alternating voltage is also generated across the secondary winding N2 (between the first input terminal 44 and the second input terminal 45). The second rectifier 4 generates and outputs a DC output voltage Vo by full-wave rectifying the alternating voltage of the secondary voltage V2.

[0073] (2.11) On-time control As described above, the control device 5 alternately turns on the first switching element Q1 and the second switching element Q2. The control device 5 controls the on-time of each of the first switching element Q1 and the second switching element Q2 to adjust the DC bus voltage Vdc, which is the voltage across the third series circuit 32, and sets the mode of the inductor current ILi to the current critical mode.

[0074] In this embodiment, when the polarity of the input voltage Vi is positive (when the potential of the first AC output terminal 81 of the AC power supply 8 is higher than the potential of the second AC output terminal 82), the control device 5 adjusts the DC bus voltage Vdc by controlling the on-time Ton1 (see FIG. 2) of the first switching element Q1 based on the DC bus voltage Vdc. Furthermore, the control device 5 sets the mode of the inductor current ILi to the current critical mode by controlling the on-time Ton2 (see FIG. 2) of the second switching element Q2. Note that the time length of the first period T1 shown in FIG. 2 is the on-time Ton1 of the first switching element Q1, and the time length of the second period T2 is the on-time Ton2 of the second switching element Q2.

[0075] Furthermore, when the polarity of the input voltage Vi is negative (when the potential of the second AC output terminal 82 of the AC power supply 8 is higher than the potential of the first AC output terminal 81), the control device 5 adjusts the DC bus voltage Vdc by controlling the on-time Ton11 (see FIG. 5) of the second switching element Q2 based on the DC bus voltage Vdc. Furthermore, the control device 5 sets the mode of the inductor current ILi to the current critical mode by controlling the on-time Ton12 (see FIG. 5) of the first switching element Q1. Note that the time length of the third period T11 shown in FIG. 5 is the on-time Ton11 of the second switching element Q2, and the time length of the fourth period T12 is the on-time Ton12 of the first switching element Q1.

[0076] 7 shows a configuration example of the control device 5. As shown in FIG. 7, the control device 5 includes a subtraction unit 51, a PI control unit 52, an on-time control unit 53, and a PWM control unit 54. The control device 5 obtains a detection value [Vdc] of the DC bus voltage Vdc, a detection value [Vi] of the input voltage Vi, and a detection value [Ii] of the input current Ii from the detection units of the DC bus voltage Vdc, the input voltage Vi, and the input current Ii, respectively. The detection value [Vdc] is the detection result of the magnitude (instantaneous value) of the DC bus voltage Vdc, the detection value [Vi] is the detection result of the magnitude (instantaneous value) of the input voltage Vi, and the detection value [Ii] is the detection result of the magnitude (instantaneous value) of the input current Ii. The detection units of the DC bus voltage Vdc, the input voltage Vi, and the input current Ii may be provided in the converter device 100 or may be provided outside the converter device 100.

[0077] The subtraction unit 51 obtains a difference between the command value Vdc* and the detection value [Vdc] of the DC bus voltage Vdc. Specifically, the subtraction unit 51 obtains a value obtained by subtracting the detection value [Vdc] from the command value Vdc* as the difference value.

[0078] When the polarity of the input voltage Vi is positive, the PI control unit 52 determines the on-time Ton1 (see FIG. 2) of the first switching element Q1 by PI control so as to bring the difference value calculated by the subtraction unit 51 closer to zero. When the detection value [Vdc] is smaller than the command value Vdc*, the PI control unit 52 lengthens the on-time Ton1 from the current state, and when the detection value [Vdc] is larger than the command value Vdc*, the PI control unit 52 shortens the on-time Ton1 from the current state. When the polarity of the input voltage Vi is positive, the PWM control unit 54 generates and outputs a first switching signal S1 reflecting the on-time Ton1 determined by the PI control unit 52, thereby controlling the on-time Ton1 of the first switching element Q1.

[0079] When the polarity of the input voltage Vi is negative, the PI control unit 52 determines the on-time Ton11 (see FIG. 5) of the second switching element Q2 by PI control so as to bring the difference value calculated by the subtraction unit 51 closer to zero. When the detection value [Vdc] is smaller than the command value Vdc*, the PI control unit 52 lengthens the on-time Ton11 from the current time, and when the detection value [Vdc] is larger than the command value Vdc*, the PI control unit 52 shortens the on-time Ton11 from the current time. When the polarity of the input voltage Vi is negative, the PWM control unit 54 generates and outputs a second switching signal S2 reflecting the on-time Ton11 determined by the PI control unit 52, thereby controlling the on-time Ton11 of the second switching element Q2.

[0080] The command value Vdc* of the DC bus voltage Vdc is determined in the control device 5 by, for example, an external command from an external device to the control device 5. In other words, the control device 5 has a function of generating the command value Vdc* based on an external command from the external device. As a communication protocol used in communication between the external device and the control device 5, for example, MODBUS, CAN, or other serial communication protocols can be used. The external device may be, for example, an external controller. It is not essential to use a specific communication protocol for communication of an external command from the external device to the control device 5.

[0081] Further, the control device 5 may be configured to hold data of the command value Vdc* in advance.

[0082] When the polarity of the input voltage Vi is positive, the on-time control unit 53 determines the on-time Ton2 (see FIG. 2) of the second switching element Q2 based on the detection values ​​[Vdc], [Vi], and [Ii], thereby setting the mode of the inductor current ILi to the current critical mode. Specifically, the on-time control unit 53 applies the acquired detection values ​​[Vdc], [Vi], and [Ii] to the following formula 1 to obtain the on-time Ton2. Here, [Li] is the inductance of the input inductor Li, and the on-time control unit 53 holds data of the inductance [Li] in advance. When the polarity of the input voltage Vi is positive, the PWM control unit 54 generates and outputs a second switching signal S2 reflecting the on-time Ton2 determined by the on-time control unit 53, thereby controlling the on-time Ton2 of the second switching element Q2.

[0083]

number

[0084] When the polarity of the input voltage Vi is negative, the on-time control unit 53 determines the on-time Ton12 (see FIG. 5) of the first switching element Q1 based on the detection values ​​[Vdc], [Vi], and [Ii], thereby setting the mode of the inductor current ILi to the current critical mode. Specifically, the on-time control unit 53 applies the acquired detection values ​​[Vdc], [Vi], and [Ii] to the following formula 2 to obtain the on-time Ton12. Here, [Li] is the inductance of the input inductor Li. When the polarity of the input voltage Vi is negative, the PWM control unit 54 generates and outputs the first switching signal S1 reflecting the on-time Ton12 determined by the on-time control unit 53, thereby controlling the on-time Ton12 of the first switching element Q1.

[0085]

number

[0086] The formulas for determining Ton2 and Ton12 are not limited to the above-mentioned formulas 1 and 2, and may be other formulas.

[0087] (2.12) Summary As described above, the converter device 100 can reduce the effective value of the input current Ii supplied from the AC power source 8 to the converter device 100 by setting the mode of the inductor current ILi to the current critical mode. As a result, the converter device 100 can achieve high efficiency while maintaining a high power factor.

[0088] 8 shows the waveforms of the input voltage Vi, the input current Ii, the inductor current ILi, and the primary AC voltage V1 in the converter device 100. The input current Ii is approximately in phase with the input voltage Vi and has an approximately sinusoidal waveform, achieving high efficiency and a high power factor.

[0089] 9 shows the waveforms of the input voltage Vi and the DC bus voltage Vdc in the converter device 100. The DC bus voltage Vdc is controlled to approach the command value Vdc*, achieving high control accuracy.

[0090] The converter device 100 controls the on-time Ton2 (see FIG. 2) of the second switching element Q2 and the on-time Ton12 (see FIG. 5) of the first switching element Q1 based on the DC bus voltage Vdc, the input voltage Vi, and the input current Ii to set the mode of the inductor current ILi to the current critical mode. The converter device 100 controls the first and second switching elements Q1 and Q2 based on the DC bus voltage Vdc, the input voltage Vi, and the input current Ii to stably control the mode of the inductor current ILi to the current critical mode.

[0091] The control device 5 may adjust the output voltage Vo by controlling the on-time Ton1 (see FIG. 2) of the first switching element Q1 and the on-time Ton11 (see FIG. 5) of the second switching element Q2 based on the output voltage Vo. In this case, the control device 5 acquires a detection value [Vo] of the output voltage Vo from a detection unit for the output voltage Vo. The detection unit for the output voltage Vo may be provided in the converter device 100 or may be provided outside the converter device 100.

[0092] 7 may use the detected value [Vo] of the output voltage Vo instead of the detected value [Vdc] of the DC bus voltage Vdc, and may use the command value Vo* of the output voltage Vo instead of the command value Vdc* of the DC bus voltage Vdc. In this case, the subtraction unit 51 calculates the difference between the command value Vo* of the output voltage Vo and the detected value [Vo].

[0093] When the polarity of the input voltage Vi is positive, the PI control unit 52 determines the on-time Ton1 (see FIG. 2) of the first switching element Q1 by PI control so as to bring the difference value calculated by the subtraction unit 51 closer to zero. When the detection value [Vo] is smaller than the command value Vo*, the PI control unit 52 lengthens the on-time Ton1 from the current state, and when the detection value [Vo] is larger than the command value Vo*, the PI control unit 52 shortens the on-time Ton1 from the current state. When the polarity of the input voltage Vi is positive, the PWM control unit 54 generates and outputs a first switching signal S1 reflecting the on-time Ton1 determined by the PI control unit 52, thereby controlling the on-time Ton1 of the first switching element Q1.

[0094] When the polarity of the input voltage Vi is negative, the PI control unit 52 determines the on-time Ton11 (see FIG. 5) of the second switching element Q2 by PI control so as to bring the difference value calculated by the subtraction unit 51 closer to zero. When the detection value [Vo] is smaller than the command value Vo*, the PI control unit 52 lengthens the on-time Ton11 from the current time, and when the detection value [Vo] is larger than the command value Vo*, the PI control unit 52 shortens the on-time Ton11 from the current time. When the polarity of the input voltage Vi is negative, the PWM control unit 54 generates and outputs a second switching signal S2 reflecting the on-time Ton11 determined by the PI control unit 52, thereby controlling the on-time Ton11 of the second switching element Q2.

[0095] (3) First Modification The converter device 100 of the first embodiment may include a control device 50 shown in FIG. 10, instead of the control device 5 shown in FIG.

[0096] As shown in FIG. 10, the control device 50 further includes a phase estimation unit 55 and a current estimation unit 56 in addition to a subtraction unit 51, a PI control unit 52, an on-time control unit 53, and a PWM control unit .

[0097] The control device 50 obtains a detection value [Vdc] of the DC bus voltage Vdc and a detection value [Vi] of the input voltage Vi from the detection units of the DC bus voltage Vdc and the input voltage Vi. The detection units of the DC bus voltage Vdc and the input voltage Vi may be provided in the converter device 100 or may be provided outside the converter device 100.

[0098] The phase estimation unit 55 estimates the phase of the input voltage Vi based on the detection value [Vi] of the input voltage Vi. For example, the phase estimation unit 55 holds in advance data of a phase table in which the magnitude and phase of the input voltage Vi are associated with each other, and refers to the phase table to determine the phase of the input voltage Vi corresponding to the detection value [Vi] as the phase estimation result. The range of the phase of the input voltage Vi is 0 or more and 2π or less. The correspondence relationship between the magnitude and phase of the input voltage Vi in the phase table is set in advance based on actual measurements or theoretical values.

[0099] The current estimation unit 56 estimates the detection value [Ii] of the input current Ii based on the phase estimation result by the phase estimation unit 55. For example, the current estimation unit 56 holds in advance data of a current table in which the phase of the input voltage Vi corresponds to the magnitude of the input current Ii, and refers to the current table to estimate the detection value [Ii] of the input current Ii corresponding to the phase of the input voltage Vi. The correspondence relationship between the phase of the input voltage Vi and the magnitude of the input current Ii in the current table is set in advance based on actual measurements or theoretical values.

[0100] Then, the current estimation unit 56 passes the estimation result of the detection value [Ii] by the current estimation unit 56 to the on-time control unit 53. The on-time control unit 53 of the control device 50 applies the detection values ​​[Vdc], [Vi], and [Ii] to the above-mentioned equations 1 and 2, similar to the operation of the control device 5, to control the on-time Ton2 (see FIG. 2) of the second switching element Q2 and the on-time Ton12 (see FIG. 5) of the first switching element Q1.

[0101] In addition, the control of the on-time Ton1 of the first switching element Q1 (see FIG. 2) and the on-time Ton11 of the second switching element Q2 (see FIG. 5) by the subtraction unit 51, the PI control unit 52, and the PWM control unit 54 of the control device 50 is similar to that of the control device 5.

[0102] In this modified example, the control device 5 estimates the input current Ii (detection value [Ii]) based on the input voltage Vi (detection value [Vi]), thereby eliminating the need for a detection unit for the input current Ii, and thus simplifying the system configuration.

[0103] In addition, in the control device 50, similar to the control device 5, the detection value [Vdc] of the DC bus voltage Vdc may be replaced by the detection value [Vo] of the output voltage Vo, and the command value Vo* of the output voltage Vo may be replaced by the command value Vdc* of the DC bus voltage Vdc (see FIG. 10).

[0104] (4) Second Modification As shown in FIG. 11, the converter device 100 of the first embodiment may include a first rectifier 20 instead of the first rectifier 2 (see FIG. 1).

[0105] The first rectifier 20 has a third switching element Q3 as the first rectifying element E1, and a fourth switching element Q4 as the second rectifying element E2. The third switching element Q3 and the fourth switching element Q4 are connected in series, and the series-connected third switching element Q3 and fourth switching element Q4 configure a fourth series circuit 23.

[0106] The first rectifier 20 also includes a third diode D3 and a fourth diode D4. The third diode D3 is connected in anti-parallel to the third switching element Q3. The fourth diode D4 is connected in anti-parallel to the fourth switching element Q4.

[0107] Each of the third to fourth switching elements Q3 to Q4 is a semiconductor switching element having a control terminal, a first main terminal, and a second main terminal. The control terminals of the third to fourth switching elements Q3 to Q4 are connected to the control device 5. The third to fourth switching elements Q3 to Q4 are turned on and off in response to a switching signal provided from the control device 5. Each of the third to fourth switching elements Q3 to Q4 is, for example, a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). More specifically, each of the third to fourth switching elements Q3 to Q4 is an n-channel MOSFET. Here, the n-channel MOSFET is a normally-off type Si-based MOSFET. In the third to fourth switching elements Q3 to Q4, the control terminal, the first main terminal, and the second main terminal are a gate terminal, a drain terminal, and a source terminal, respectively.

[0108] The drain terminal of the third switching element Q3 is connected to the drain terminal of the first switching element Q1. The source terminal of the third switching element Q3 is connected to the drain terminal of the fourth switching element Q4. The source terminal of the fourth switching element Q4 is connected to the source terminal of the second switching element Q2. The connection point between the source terminal of the third switching element Q3 and the drain terminal of the fourth switching element Q4 constitutes a connection point 22. In the first rectifier 20, the first AC output terminal 81 of the AC power supply 8 is connected to the connection point 22 via the input terminal 11 and the filter unit 1.

[0109] The third to fourth diodes D3 to D4 are parasitic diodes of the MOSFETs of the third to fourth switching elements Q3 to Q4, respectively. Each of the third to fourth diodes D3 to D4 has an anode and a cathode. The anode and cathode of each of the third to fourth diodes D3 to D4 are connected to the source terminal and the drain terminal of the corresponding one of the third to fourth switching elements Q3 to Q4, respectively.

[0110] The third and fourth switching elements Q3 to Q4 are controlled by a control device 5. Specifically, the control device 5 alternately turns on the third switching element Q3 and the fourth switching element Q4 to synchronously rectify the input voltage Vi. That is, the first rectifier 20 includes the third switching element Q3 and the fourth switching element Q4 as the first rectifying element E1 and the second rectifying element E2, and performs synchronous rectification.

[0111] (Embodiment 2) A converter device 100A according to the second embodiment will be described below with reference to Fig. 12 to Fig. 14. Regarding the converter device 100A according to the second embodiment, components similar to those of the converter device 100 according to the first embodiment (see Fig. 1) are given the same reference numerals and descriptions thereof will be omitted as appropriate.

[0112] The converter device 100A shown in Fig. 12 further includes a detection winding Ns magnetically coupled to the input inductor Li. The converter device 100A includes a control device 5A instead of the control device 5 of the converter device 100. The control device 5A detects the inductor current ILi using the detection winding Ns. The control device 5A controls the first and second switching elements Q1 and Q2 based on the detection result of the inductor current ILi so that the mode of the inductor current ILi becomes a current critical mode.

[0113] Specifically, the detection winding Ns is magnetically coupled to the input inductor Li, and a detection voltage Vs is generated across the detection winding Ns due to a change in the inductor current ILi. The detection winding Ns is connected to the control device 5A, and the detection voltage Vs is input to the control device 5A.

[0114] As shown in FIG. 13, the control device 5A includes a subtraction unit 51, a PI control unit 52, a PWM control unit 54, a signal rectification unit 57, and a comparator 58.

[0115] The signal rectifier 57 performs full-wave rectification on the detection voltage Vs to output a rectified signal Ya, which is a voltage signal. The comparator 58 compares the rectified signal Ya with a threshold voltage Va. The threshold voltage Va is a positive value close to zero. The comparator 58 outputs a binary comparison signal Yb, whose voltage level is set according to the comparison result between the rectified signal Ya and the threshold voltage Va. If the rectified signal Ya is greater than the threshold voltage Va, the comparator 58 outputs the comparison signal Yb, whose voltage level is set to a high level, and if the rectified signal Ya is less than the threshold voltage Va, the comparator 58 outputs the comparison signal Yb, whose voltage level is set to a low level.

[0116] The PWM control unit 54 controls the first and second switching elements Q1 and Q2 based on the voltage level of the comparison signal Yb, thereby setting the mode of the inductor current ILi to the current critical mode.

[0117] Specifically, when the polarity of the input voltage Vi is positive, the waveforms of the inductor current ILi, the rectified signal Ya, and the comparison signal Yb are as shown in FIG.

[0118] As shown in the upper part of FIG. 14, the inductor current ILi increases during a first period T1 when the first switching element Q1 is on and the second switching element Q2 is off, and decreases during a second period T2 when the first switching element Q1 is off and the second switching element Q2 is on.

[0119] The detection voltage Vs is generated when the inductor current ILi changes, but when the inductor current ILi becomes zero, the detection voltage Vs drops abruptly to zero. Therefore, when the inductor current ILi drops to zero in the second period T2, the detection voltage Vs drops abruptly to zero. Thus, as shown in the middle part of Figure 14, the rectified signal Ya obtained by rectifying the detection voltage Vs becomes larger than the threshold voltage Va when the inductor current ILi is flowing, and becomes smaller than the threshold voltage Va when the inductor current ILi drops to zero in the second period T2.

[0120] Therefore, as shown in the lower part of FIG. 14, the comparison signal Yb output by the comparator 58 is at a high level when the inductor current ILi flows, and is at a low level when the inductor current ILi decreases to zero in the second period T2.

[0121] The PWM control unit 54 determines whether the polarity of the input voltage Vi is positive or negative, based on the detected value [Vi] of the input voltage Vi.

[0122] When the polarity of the input voltage Vi is positive, the PWM control unit 54 switches the second switching signal S2 from high level to low level at the timing when the comparison signal Yb switches from high level to low level, thereby setting the mode of the inductor current ILi to the current critical mode. That is, when the polarity of the input voltage Vi is positive, the control device 5A controls the on-time Ton2 (see FIG. 2) of the second switching element Q2 so that the second period T2 (see FIG. 2) ends at the timing when the comparison signal Yb switches from high level to low level.

[0123] Similarly, when the polarity of the input voltage Vi is negative, the PWM control unit 54 switches the first switching signal S1 from high level to low level at the timing when the comparison signal Yb switches from high level to low level, thereby setting the mode of the inductor current ILi to the current critical mode. That is, when the polarity of the input voltage Vi is negative, the control device 5A controls the on-time Ton12 (see FIG. 5) of the first switching element Q1 so that the fourth period T12 (see FIG. 5) ends at the timing when the comparison signal Yb switches from high level to low level.

[0124] In this way, the converter device 100A controls the on-time Ton2 (see FIG. 2) of the second switching element Q2 and the on-time Ton12 (see FIG. 5) of the first switching element Q1 based on the detection voltage Vs of the detection winding Ns, thereby setting the mode of the inductor current ILi to the critical current mode. As a result, the converter device 100A can stably control the mode of the inductor current ILi to the critical current mode.

[0125] The control of the on-time Ton1 of the first switching element Q1 (see FIG. 2) and the on-time Ton11 of the second switching element Q2 (see FIG. 5) by the subtraction unit 51, the PI control unit 52, and the PWM control unit 54 of the control device 5A is similar to that of the control device 5.

[0126] Furthermore, in the control device 5A, as in the control device 5, the detection value [Vo] of the output voltage Vo may be used instead of the detection value [Vdc] of the DC bus voltage Vdc, and the command value Vo* of the output voltage Vo may be used instead of the command value Vdc* of the DC bus voltage Vdc (see FIG. 13).

[0127] (Modification) The above-mentioned first and second embodiments are merely one of various embodiments of the present disclosure. The above-mentioned first and second embodiments can be modified in various ways depending on the design and the like as long as the object of the present disclosure can be achieved. In addition, the configurations of the above-mentioned first and second embodiments, the first modified example, and the second modified example can be combined.

[0128] For example, each of the first switching element Q1 and the second switching element Q2 is not limited to a GaN-based MOSFET, and may be, for example, a Si-based MOSFET, a SiC-based MOSFET, or an IGBT (Insulated Gate Bipolar Transistor).

[0129] In addition, each of the third switching element Q3 and the fourth switching element Q4 is not limited to an n-channel MOSFET, but may be a p-channel MOSFET. In addition, the MOSFETs constituting the third switching element Q3 and the fourth switching element Q4 are not limited to Si-based MOSFETs, but may be, for example, SiC-based MOSFETs, IGBTs, or GaN-based MOSFETs.

[0130] The inductor L1 is not limited to being connected between the first output port 34 and the primary winding N1, but may be connected between the second output port 35 and the primary winding N1.

[0131] The input inductor Li is not limited to being connected between the AC power supply 8 and the half-bridge inverter 3, but may be connected between the AC power supply 8 and the first rectifier 2. In other words, the input inductor Li is not limited to being connected between the input terminal 12 and the connection point 33, but may be connected between the input terminal 11 and the connection point 22. Furthermore, both the input inductor Li connected between the input terminal 12 and the connection point 33, and the input inductor Li connected between the input terminal 11 and the connection point 22 may be provided.

[0132] (summary) A converter device (100, 100A) according to a first aspect of the embodiment includes a first rectifier (2, 20), a half-bridge inverter (3), an input inductor (Li), a transformer (Tr1), a second rectifier (4), an inductor (L1), and a control device (5, 50, 5A). The first rectifier (2, 20) includes a first series circuit (21) in which a first rectifier element (E1) and a second rectifier element (E2) are connected in series, and a first AC output terminal (81) of an AC power source (8) is connected to a connection point (22) between the first rectifier element (E1) and the second rectifier element (E2). The half-bridge inverter (3) includes a second series circuit (31) including a first switching element (Q1) and a second switching element (Q2), and a third series circuit (32) including a first capacitor (C1) and a second capacitor (C2). The second series circuit (31) and the third series circuit (32) are connected in parallel to the first series circuit (21), and the second AC output terminal (82) of the AC power supply (8) is connected to a connection point (33) between the first switching element (Q1) and the second switching element (Q2). The input inductor (Li) is connected between the AC power supply (8) and the first rectifier (2, 20) or the half-bridge inverter (3). The transformer (Tr1) includes a primary winding (N1) and a secondary winding (N2), and the primary winding (N1) is connected between a first output terminal (34) between the first switching element (Q1) and the second switching element (Q2) and a second output terminal (35) between the first capacitor (C1) and the second capacitor (C2). The second rectifier (4) is connected to the secondary winding (N2) of the transformer (Tr1) and outputs an output voltage (Vo) obtained by rectifying a secondary voltage generated in the secondary winding (N2). The inductor (L1) acts on an electric path between the first output terminal (34) or the second output terminal (35) and the primary winding (N1). The control device (5, 50, 5A) controls at least the half-bridge inverter (3). The control device (5, 50, 5A) alternately turns on the first switching element (Q1) and the second switching element (Q2).The control device (5, 50, 5A) adjusts the DC bus voltage (Vdc) or the output voltage (Vo) by controlling the on-time (Ton1, Ton11) of one of the first switching element (Q1) and the second switching element (Q2) based on the DC bus voltage (Vdc) or the output voltage (Vo) which is the voltage across the third series circuit (32). The control device (5, 50, 5A) sets the mode of the inductor current (ILi) flowing through the input inductor (Li) to a current critical mode by controlling the on-time (Ton2, Ton12) of the other of the first switching element (Q1) and the second switching element (Q2).

[0133] The above-described converter device (100, 100A) can reduce the effective value of the input current (Ii) supplied from the AC power source (8) to the converter device (100, 100A) by setting the mode of the inductor current (ILi) to a critical current mode. As a result, the converter device (100, 100A) can achieve high efficiency while maintaining a high power factor.

[0134] In the converter device (100, 100A) of the second aspect of the embodiment, in the first aspect, when the potential of the first AC output terminal (81) is higher than the potential of the second AC output terminal (82), it is preferable that the control device (5, 50, 5A) adjusts the DC bus voltage (Vdc) or the output voltage (Vo) by controlling the on-time (Ton1) of the first switching element (Q1) based on the DC bus voltage (Vdc) or the output voltage (Vo) and sets the mode of the inductor current (ILi) to a current critical mode by controlling the on-time (Ton2) of the second switching element (Q2). When the potential of the first AC output terminal (81) is lower than the potential of the second AC output terminal (82), it is preferable that the control device (5, 50, 5A) adjusts the DC bus voltage (Vdc) or the output voltage (Vo) by controlling the on-time (Ton11) of the second switching element (Q2) based on the DC bus voltage (Vdc) or the output voltage (Vo), and sets the mode of the inductor current (ILi) to a current critical mode by controlling the on-time (Ton12) of the first switching element (Q1).

[0135] The above-described converter device (100, 100A) can achieve high efficiency while maintaining a high power factor.

[0136] In the converter device (100) of the third aspect of the embodiment, in the first or second aspect, it is preferable that the control device (5, 50) sets the mode of the inductor current (ILi) to the critical current mode by controlling the on-time (Ton2, Ton12) of the other of the first switching element (Q1) and the second switching element (Q2) based on the DC bus voltage (Vdc) or the output voltage (Vo), the input voltage (Vi) which is the voltage of the AC power supply (8), and the input current (Ii) from the AC power supply (8).

[0137] The above-described converter device (100) can stably perform control so that the mode of the inductor current (ILi) is the critical current mode.

[0138] In the converter device (100) according to the fourth aspect of the embodiment, in the third aspect, it is preferable that the control device (50) estimates the input current (Ii) based on the input voltage (Vi).

[0139] The above-described converter apparatus (100) does not require a detector for detecting the input current (Ii), and the system configuration can be simplified.

[0140] In the converter device (100A) according to the fifth aspect of the embodiment, in the first or second aspect, it is preferable that the converter device (100A) further includes a detection winding (Ns) magnetically coupled to the input inductor (Li). It is preferable that the control device (5A) controls the on-time (Ton2, Ton12) of the other of the first switching element (Q1) and the second switching element (Q2) based on the detection voltage (Vs) which is the voltage of the detection winding (Ns) to set the mode of the inductor current (ILi) to a current critical mode.

[0141] The above-described converter device (100A) can stably perform control to set the mode of the inductor current (ILi) to the critical current mode.

[0142] In the converter device (100, 100A) of the sixth aspect of the embodiment, in any one of the first to fifth aspects, it is preferable that the first rectifier element (E1) and the second rectifier element (E2) are diodes (D1, D2), respectively.

[0143] In the above-described converter device (100, 100A), the first rectifier (2) can be realized with a simple configuration.

[0144] In the converter device (100, 100A) of the seventh aspect of the embodiment, in any one of the first to fifth aspects, each of the first rectifier element (E1) and the second rectifier element (E2) is preferably a switching element (Q3, Q4), and the first rectifier (20) performs synchronous rectification.

[0145] The above-described converter device (100, 100A) can suppress the loss in the first rectifier (2). [Explanation of symbols]

[0146] 100, 100A converter device 2, 20 1st rectifier 21 1st series circuit 22 Connection points 3 Half-bridge inverter 31 Second series circuit 32 Third series circuit 33 Connection points 34 First output terminal 35 Second output terminal 4 2nd rectifier 5, 50, 5A Control Unit 8 AC power supply 81 1st AC output terminal 82 2nd AC output terminal Li Input Inductor Tr1 Transformer L1 Inductor E1 First rectifier element E2 Second rectifier element Q1 First switching element Q2 Second switching element Q3 Third switching element Q4 Fourth switching element C1 First capacitor C2 Second capacitor N1 Primary winding N2 Secondary winding Ns detection winding D1 First diode D2 Second diode Vo output voltage Vdc DC bus voltage Vi input voltage Vs Detection voltage Ii Input current Ton1, Ton2, Ton11, Ton12 On time

Claims

1. a first rectifier including a first series circuit in which a first rectifier element and a second rectifier element are connected in series, the first AC output terminal of an AC power supply being connected to a connection point between the first rectifier element and the second rectifier element; a half-bridge inverter including a second series circuit of a first switching element and a second switching element, and a third series circuit of a first capacitor and a second capacitor, the second series circuit and the third series circuit being connected in parallel to the first series circuit, and a second AC output terminal of the AC power supply being connected to a connection point between the first switching element and the second switching element; an input inductor connected between the AC power source and the first rectifier or the half-bridge inverter; a transformer including a primary winding and a secondary winding, the primary winding being connected between a first output terminal between the first switching element and the second switching element and a second output terminal between the first capacitor and the second capacitor; a second rectifier connected to the secondary winding of the transformer and configured to rectify a secondary voltage generated in the secondary winding and output an output voltage; an inductor acting on an electric path between the first output terminal or the second output terminal and the primary winding; A control device that controls at least the half-bridge inverter, The control device includes: The first switching element and the second switching element are alternately turned on; adjusting the DC bus voltage or the output voltage by controlling an on-time of one of the first switching element and the second switching element based on a DC bus voltage, which is a voltage across the third series circuit, or the output voltage; By controlling the on-time of the other of the first switching element and the second switching element, the mode of the inductor current flowing through the input inductor is set to a current critical mode. Converter device.

2. The control device includes: When the potential of the first AC output terminal is higher than the potential of the second AC output terminal, adjusting the DC bus voltage or the output voltage by controlling an on-time of the first switching element based on the DC bus voltage or the output voltage; By controlling an on-time of the second switching element, the mode of the inductor current is set to the current critical mode; When the potential of the first AC output terminal is lower than the potential of the second AC output terminal, adjusting the DC bus voltage or the output voltage by controlling an on-time of the second switching element based on the DC bus voltage or the output voltage; The on-time of the first switching element is controlled to set the inductor current mode to the critical current mode. The converter device of claim 1.

3. The control device controls an on-time of the other of the first switching element and the second switching element based on the DC bus voltage or the output voltage, an input voltage which is a voltage of the AC power supply, and an input current from the AC power supply, thereby setting the mode of the inductor current to the current critical mode. The converter device of claim 1.

4. The control device estimates the input current based on the input voltage. The converter device according to claim 3.

5. a sense winding magnetically coupled to the input inductor; The control device controls an on-time of the other of the first switching element and the second switching element based on a detection voltage that is a voltage of the detection winding, thereby setting the mode of the inductor current to the current critical mode. The converter device of claim 1.

6. Each of the first rectifying element and the second rectifying element is a diode. The converter device of claim 1.

7. each of the first rectifying element and the second rectifying element is a switching element; The first rectifier performs synchronous rectification. The converter device of claim 1.

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