JP6988902B2 - AC / DC converter circuit - Google Patents

Description

The present invention relates to an AC / DC converter circuit.

Conventionally, a step-down AC / DC conversion circuit that converts an input AC voltage into a DC voltage having a voltage lower than the peak voltage of the AC voltage is known. For example, in Patent Document 1, the AC voltage rectified by a bridge diode in full wave is "chopped" by a switch element controlled by PWM (Pulse Width Modulation), and is determined by the duty ratio of the pulse in PWM control. A circuit that outputs a DC voltage having a certain magnitude is disclosed.

Japanese Unexamined Patent Publication No. 2012-169126

In the step-down AC / DC conversion circuit of Patent Document 1, the absolute value of the AC input voltage input to the circuit is higher than the DC voltage output by the circuit, especially due to the existence of the rectifier circuit that rectifies the AC input. When it becomes low, no current flows on the input side.

As a result, the voltage waveform and the current waveform of the AC input do not match, and the power factor of the AC input becomes low. In particular, the closer the output DC voltage is to the peak voltage of the AC input, the lower the power factor of the AC input.

An object of the present invention is to maintain a high power factor of an AC input while outputting a high DC voltage by using a step-down AC / DC conversion circuit.

The AC / DC converter circuit of one exemplary embodiment of the present application includes an input unit, an output unit, a first sub-AC / DC converter circuit, and a second sub-AC / DC converter circuit. The input unit has a first input terminal and a second input terminal. The output unit has a first output terminal and a second output terminal.

The first sub-AC / DC converter circuit includes an inductor element, a first capacitor element, and a first rectifier element. One end of the inductor element is connected to the first input terminal via a switching element. One end of the first capacitor element is connected to the other end of the inductor element, and the other end is connected to the first output terminal. In the first rectifying element, one end on the cathode side is connected to the second input terminal, and the other end on the anode side is connected to the first output terminal.

The second sub-AC / DC conversion circuit includes an inductor element, a switching element, a second capacitor element, and a second rectifier element. One end of the second capacitor element is connected to the other end of the inductor element, and the other end is connected to the second output terminal. In the second rectifying element, one end on the anode side is connected to the second input terminal, and the other end on the cathode side is connected to the second output terminal.

In the AC / DC conversion circuit of one exemplary embodiment of the present application, the first capacitor element of the first sub-AC / DC conversion circuit, which is a step-down AC / DC conversion circuit, and the second sub-AC / DC conversion circuit, which is a step-down AC / DC conversion circuit, are used. The second capacitor element is connected in series between the first output terminal and the second output terminal. Therefore, each of the two step-down type sub-AC / DC converter circuits divides the DC voltage output to the output unit. As a result, the rectifying element of each sub-AC / DC conversion circuit is turned on for one cycle of the AC input input to the input unit, as compared with the case where the same DC voltage is output by one sub-AC / DC conversion circuit. You can lengthen the time. As a result, the power factor of the AC input can be increased.

FIG. 1 is a diagram showing a configuration of an AC / DC converter circuit according to the first embodiment. FIG. 2 is a time chart of the potential on the live side and the potential on the neutral side of the AC power supply. FIG. 3 is a time chart showing a switching signal of a switching element. FIG. 4A is a diagram showing a current flow when the AC input voltage is positive and the switching element is in the ON state. FIG. 4B is a diagram showing a current flow when the AC input voltage is positive and the switching element is in the off state. FIG. 5A is a diagram showing a current flow when the AC input voltage is negative and the switching element is in the ON state. FIG. 5B is a diagram showing a current flow when the AC input voltage is negative and the switching element is in the off state. FIG. 6 is a diagram showing an input current flowing through the AC / DC converter circuit according to the first embodiment. FIG. 7 is a diagram showing an output voltage of the AC / DC converter circuit according to the first embodiment. FIG. 8 is a diagram showing a configuration of an AC / DC converter circuit of a comparative example. FIG. 9 is a diagram showing an input current flowing through the AC / DC converter circuit of the comparative example. FIG. 10 is a diagram showing a configuration of an AC / DC converter circuit according to a second embodiment. FIG. 11 is a diagram showing the configuration of the AC / DC converter circuit according to the third embodiment. FIG. 12 is a diagram showing the configuration of the AC / DC converter circuit according to the fourth embodiment. FIG. 13 is a diagram showing the configuration of the AC / DC converter circuit according to the fifth embodiment. FIG. 14 is a diagram showing the configuration of the AC / DC converter circuit according to the sixth embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The scope of the present invention is not limited to the following embodiments, and can be arbitrarily changed within the scope of the technical idea of the present invention.

In the following description, the "zero cross point" of the potential or voltage means the timing at which the AC potential or voltage becomes 0V. The "alternating current period" refers to the time required for the phase of a voltage or current that changes in a sinusoidal shape to advance by 2π (radians) from the reference phase. The "sign" of voltage, current, etc. means the positive or negative of voltage, current, etc. For example, the sign of "negative voltage" is "-(minus)" and the sign of "positive voltage" is "+ (plus)".

The "switching cycle" refers to a cycle when a switching element or the like periodically switches between an on state and an off state. The "duty ratio" refers to the ratio of the time length in which the switching element or the like is on to the switching cycle.

In the description using the drawings, the "upper side" means the upper part of the paper surface representing the drawings, and the "lower side" means the lower part of the paper surface representing the drawings.

(Embodiment 1)

[1-1. overall structure]

FIG. 1 is a diagram showing an overall configuration of an AC / DC converter circuit according to the first embodiment. The AC / DC converter circuit 1 includes an input unit 11, a first sub-AC / DC converter circuit 13, a second sub-converter AC / DC converter circuit 15, an output unit 17, and a control circuit 19.

The input unit 11 is a connection terminal for connecting the AC power supply PS to the first sub-AC / DC converter circuit 13 and the second sub-AC / DC converter circuit 15. In the present embodiment, the AC power supply PS is a single-phase AC power supply having two poles, a first pole P1 and a second pole P2.

In the present embodiment, the first pole P1 of the AC power supply PS is a pole on the live side whose potential changes in a sinusoidal shape in a predetermined AC cycle, as shown in the upper figure of FIG. Hereinafter, the potential on the live side is referred to as "VL". Therefore, the potential VL on the live side can be expressed by the formula A * sin {(2π / T) * t}. Here, "T" is an alternating current cycle. "T" is any time. "A" is the amplitude of the potential VL on the live side.

On the other hand, the second pole P2 is a neutral-side pole whose potential does not change with time, as shown in the lower figure of FIG. Hereinafter, the potential on the neutral side is referred to as "VN". The potential VN on the neutral side is, for example, always maintained at a constant potential B (V). For example, the potential VN on the neutral side is always maintained at 0 V.

The AC power supply PS is, for example, a generally supplied household or commercial AC power supply, an inverter power supply, an AC generator, or the like. The input unit 11 may be connected to the AC power supply PS via a transformer (not shown). In this case, the input unit 11 inputs a voltage lower or higher than the voltage output from the AC power supply PS.

Since the AC power supply PS has two poles, the input unit 11 of the present embodiment has two terminals, a first input terminal I1 and a second input terminal I2. The first input terminal I1 connects the first pole P1 of the AC power supply PS. On the other hand, the second input terminal I2 connects the second pole P2 of the AC power supply PS.

Thus, the AC power source PS is between the AC input voltage _{V in} that is determined by the potential difference between the potential VL and the neutral side of the potential VN live side (VL-VN), the first input terminal I1 and the second input terminal I2 Output to. Using the above expression for the electric potential VL and the neutral side potential VN live side, the AC input voltage _{V in,} for example, can be expressed by the equation of A * sin {(2π / T ) * t} -B.

The first sub-AC / direct current conversion circuit 13 is a circuit existing at a location surrounded by a two-point chain line in FIG. 1, and the potential of the first input terminal I1 is higher than the potential of the second input terminal I2 (VL>. VN) time, i.e., the AC input voltage _{V in} is at the positive voltage, and outputs a first DC output voltage _{V out1} converts the AC input voltage _{V in} input from the input unit 11 into a DC voltage.

The second sub-AC / direct current conversion circuit 15 is a circuit existing at a location surrounded by a single point chain wire in FIG. 1, and the potential of the first input terminal I1 is lower than the potential of the second input terminal I2 (VL <VN). ) time, i.e., output when the AC input voltage V _in is of negative voltage, the second DC output voltage V _out2 converts the AC input voltage V _in input from the input unit 11 into a DC voltage.

The circuit configurations of the first sub-AC / DC converter circuit 13 and the second sub-AC / DC converter circuit 15 according to the present embodiment will be described in detail later.

The output unit 17 has a first output terminal O1 and a second output terminal O2, and a load LO driven by the AC / DC converter circuit 1 is connected between them. The load LO is, for example, a motor, a lighting device, various electronic devices, a storage battery, or the like. When the load LO is a motor, an inverter circuit may be appropriately connected between the first output terminal O1 and the second output terminal O2 and the load LO. When the load LO is an electronic device or a storage battery, a converter circuit may be appropriately connected between the first output terminal O1 and the second output terminal O2 and the load LO.

The control circuit 19 is, for example, hardware including a PWM signal generation circuit, a potential measurement circuit and / or a current measurement circuit, or a SoC (System on Chip) in which these circuits are formed on a chip. The control circuit 19 controls the first sub-AC / DC converter circuit 13 and the second sub-AC / DC converter circuit 15. Further, the control circuit 19, the potential of the first input terminal I1, i.e., may be measured AC input voltage _{V in.}

Alternatively, the control circuit 19 may be a computer system including a CPU, a storage element (RAM, ROM, etc.), an A / D interface, a D / A interface, and the like. In this case, a program that can be executed by the control circuit 19 may control the on state and the off state of the switching circuit SW. Further, the storage element of the control circuit 19 may store the program.

Further, the control circuit 19 may have an interface that can be connected to an external device. In this case, an external device connected to the interface may control the on state and the off state of the switching circuit SW via the control circuit 19.

[1-2. Configuration of the first sub-converter / direct conversion circuit]

Hereinafter, the circuit configuration of the first sub-AC / DC converter circuit 13 will be described with reference to FIG. As shown in FIG. 1, the first sub-AC / DC converter circuit 13 includes an inductor element L, a switching circuit SW, a first capacitor element C1, and a first rectifier element D1.

The inductor element L is an element having an inductance component. The inductor element L is, for example, a coil. One end of the inductor element L is connected to the first input terminal I1 via the switching circuit SW.

By connecting the inductor element L to the first input terminal I1 (AC power supply PS) via the switching circuit SW, the inductor element L, the switching circuit SW, and the first input terminal I1 are connected in series.

The switching circuit SW, than the frequency of the AC input voltage V _in an ON state and an OFF state repeatedly switched at a high frequency, between the inductor element L and the first input terminal I1 in element connected or disconnected quickly be. The switching circuit SW of the present embodiment is preferably a bidirectional switch having a high withstand voltage in both directions. Therefore, the switching circuit SW of the present embodiment includes switching characteristics such as a MOSFET (Metal Oxide Semiconductor Field Transistor), a field effect transistor other than the MOSFET, a bipolar transistor, an IGBT (Insulated Gate Bipolar Transistor), and a thyristor. A switching circuit configured to be capable of bidirectional operation by combining a plurality of elements and / or diodes is used. When a MOSFET is used for the switching circuit SW, the gate pole becomes the control pole of the switching circuit SW.

Further, when a high withstand voltage is not required in both directions, for example, when the operating power of the AC / DC converter circuit 1 is small, the switching circuit SW is composed of only semiconductor elements having the above switching characteristics. May be.

The first capacitor element C1 is a capacitor having a relatively large capacitance such as an electrolytic capacitor. One end of the first capacitor element C1 is connected to the side opposite to the side connected to the switching circuit SW of the inductor element L. On the other hand, the other end of the first capacitor element C1 is connected to the first output terminal O1.

The first capacitor element C1 is charged by a current supplied from the AC power supply PS via the inductor element L, and is repeatedly discharged by supplying electric power to the load LO, so that the first capacitor element C1 becomes substantially constant at both ends. 1 Generates a DC output voltage V _out1. That is, the first capacitor element C1 functions as a "smoothing capacitor" in the first sub-AC / DC converter circuit 13.

In the first rectifying element D1, the cathode side is connected to the second input terminal I2, and the anode side is connected to the first output terminal O1. Therefore, the first rectifying element D1, when the potential of the first input terminal I1 is higher than the potential of the second input terminal I2, i.e., when the AC input voltage V _in is positive, in a conductive state, the first sub-AC to DC The conversion circuit 13 is operated.

The first sub-AC / DC converter circuit 13 further includes a third rectifying element D3. The third rectifying element D3 connects the cathode side between the switching circuit SW and the inductor element L. Further, the anode side is connected to the first output terminal O1.

As a result, the third rectifier element D3 forms a closed circuit together with the inductor element L and the first capacitor element C1 when the switching circuit SW is turned off while the first sub-converter AC / DC converter circuit 13 is in operation. As a result, when the switching circuit SW is in the off state, a current can be passed through the closed circuit formed by the inductor element L, the first capacitor element C1, and the third rectifying element D3.

The first rectifying element D1 and the third rectifying element D3 are diodes such as, for example, a PN diode and a Schottky barrier diode.

By having the configuration described above, first auxiliary AC-DC converter circuit 13 may be configured to AC-DC conversion circuit of the step-down chopper type AC input voltage V _in is activated when positive. That is, the first sub-AC-DC conversion circuit 13, when the AC input voltage V _in a positive voltage is an AC input voltage V _in, the absolute value below the DC voltage of the peak value of the AC input voltage V _in the 1 Can be converted to DC output voltage V _out1.

In the step-down chopper type first sub-AC / DC conversion circuit 13, _{the first capacitor element C1 that outputs the first DC output voltage V out1} and the inductor element L are connected to the AC power supply PS via the switching circuit SW. To. As a result, it is possible to avoid an inrush current flowing through the first capacitor element C1 or the like when the operation of the first sub-AC / DC converter circuit 13 is started.

For example, when the AC / DC converter circuit 1 starts operating, the switching circuit SW is in the off state. Thus, even greater overvoltage than the AC input voltage V _in when the turn on the AC power source PS is applied to the input unit 11, does not the overvoltage is applied to such first capacitor element C1. As a result, it is possible to prevent the inrush current generated by the overvoltage from flowing to the element included in the first sub-AC / DC converter circuit 13.

[1-3. Configuration of the second sub-converter-converter circuit]

Hereinafter, the circuit configuration of the second secondary AC / DC converter circuit 15 will be described with reference to FIG. As shown in FIG. 1, the second sub-AC / DC converter circuit 15 includes a second capacitor element C2, a second rectifier element D2, the above-mentioned inductor element L, and a switching circuit SW.

The second capacitor element C2 is a capacitor having a relatively large capacitance such as an electrolytic capacitor. One end of the second capacitor element C2 is connected to the side opposite to the side connected to the switching circuit SW of the inductor element L. On the other hand, the other end of the second capacitor element C2 is connected to the second output terminal O2.

The second capacitor element C2 is charged by a current supplied from the AC power supply PS via the inductor element L, and is repeatedly discharged by supplying electric power to the load LO, so that the second capacitor element C2 becomes substantially constant at both ends. 2 Generates a DC output voltage V _out2. That is, the second capacitor element C2 functions as a "smoothing capacitor" in the second sub-converter AC / DC converter circuit 15.

By connecting one end of the second capacitor element C2 to the inductor element L and the other end to the second output terminal O2, the first capacitor element C1 and the second capacitor element C2 of the first sub-converter AC / DC converter circuit 13 are connected. , The first output terminal O1 and the second output terminal O2 are connected in series.

The second rectifying element D2 connects the anode side to the second input terminal I2 and the cathode side to the second output terminal O2. Thus, the second rectifying element D2, when the potential of the first input terminal I1 is lower than the potential of the second input terminal I2, i.e., when the AC input voltage V _in is negative, a conductive state, the second sub-AC to DC The conversion circuit 15 is operated.

The second sub-AC / converter conversion circuit 15 further includes a fourth rectifying element D4. The fourth rectifying element D4 connects the anode side between the switching circuit SW and the inductor element L. Further, the cathode side is connected to the second output terminal O2.

As a result, the fourth rectifying element D4 forms a closed circuit together with the inductor element L and the second capacitor element C2 when the switching circuit SW is turned off while the second sub-converter AC / DC converter circuit 15 is in operation. As a result, when the switching circuit SW is in the off state, a current can be passed through the closed circuit formed by the inductor element L, the second capacitor element C2, and the fourth rectifier element D4.

The second rectifying element D2 and the fourth rectifying element D4 are diodes such as, for example, a PN diode and a Schottky barrier diode.

By having the configuration described above, the second sub-AC-DC conversion circuit 15 may be configured to AC-DC conversion circuit of the step-down chopper type AC input voltage V _in is operated at negative. That is, the second sub-AC-DC conversion circuit 15, when the AC input voltage V _in is negative voltage, the AC input voltage V _in, the absolute value below the DC voltage of the peak value of the AC input voltage V _in the 2 Can be converted to DC output voltage V _out2.

In the second sub-AC / DC conversion circuit 15 which is a step-down chopper type, similarly to the first sub-AC / direct conversion circuit 13, when the AC power supply PS is turned on and the operation of the second sub-AC / direct conversion circuit 15 is started, the second capacitor element is started. It is possible to avoid the inrush current flowing through C2 and the like.

As shown in FIG. 1, the inductor element L and the switching circuit SW are shared by the first sub-AC / DC converter circuit 13 and the second sub-AC / DC converter circuit 15. As a result, the number of elements in the AC / DC converter circuit 1 can be reduced.

[1-4. Effect of AC / DC converter circuit according to the first embodiment]

In the AC / DC converter circuit 1, the first capacitor element C1 and the second capacitor element C2 are connected in series. Further, the first DC output voltage V _out1 is generated in the first capacitor element C1, and the second DC output voltage V _out2 is generated in the second capacitor element C2. _{As a result, the AC / DC conversion circuit 1 has a voltage V out1} + V _out2, which is the sum of _{the first DC output voltage V out1} and the second DC output voltage V _out2 , between the first output terminal O1 and the second output terminal O2. , The output voltage can be output as _{V out.}

Further, the AC-DC converter circuit 1, the first sub-AC-DC conversion circuit 13 may be operated when the AC input voltage V _in is positive, and the second sub-AC-DC converter circuit 15 when the AC input voltage V _in is negative It should work to. This, in each sub-AC-DC conversion circuit, which means that the AC input voltage V _in may be half-wave rectified. Therefore, in each of the first sub-AC / DC converter circuit 13 and the second sub-AC / DC converter circuit 15, there is only one rectifying element that determines the direction of the current in these sub-AC / DC converter circuits.

As a result, the AC / DC conversion circuit 1 can reduce the conduction loss generated by the current flowing in a state where a voltage equal to or higher than a predetermined value is applied to the rectifying element, as compared with the AC / DC conversion circuit having a bridge diode.

Further, as shown in FIG. 1, in the AC / DC conversion circuit 1, one end of the inductor element L, the cathode side of the third rectifying element D3, and the anode side of the fourth rectifying element D4 are AC via the switching circuit SW. It is connected to the first input terminal I1 to which the first pole P1 of the power supply PS is connected.

As a result, when the switching circuit SW is switched between the on state and the off state, the first output terminal O1 connecting the anode side of the third rectifying element D3 or the cathode side of the fourth rectifying element D4 is connected. It is possible to avoid the occurrence of common node noise due to a sudden change in the potential of the second output terminal O2.

[1-5. Operation of the AC / DC converter circuit according to the first embodiment]

Hereinafter, the operation of the AC / DC converter circuit 1 according to the first embodiment will be described. In the present embodiment, the control circuit 19, to the AC input voltage V _in shown in the upper diagram of FIG. 3, pulse-shaped switching a switching signal circuit having a period shorter than the AC cycle as shown in the lower part of FIG. 3 SW Input to the control pole of. As a result, the switching circuit SW repeatedly switches between the on state and the off state in a cycle shorter than the AC cycle. That is, on and off states of the switching circuit SW, than the frequency of the AC input voltage V _in is switched at high frequencies. In the present embodiment, the switching signal for turning on the switching circuit SW is a positive voltage having a predetermined voltage value. On the other hand, the switching signal that turns off the switching circuit SW is 0 voltage.

Further, the control circuit 19 switches between an on state and an off state of the switching circuit SW by PWM control by outputting a switching signal as shown in the lower figure of FIG. Specifically, the control circuit 19 increases the duty ratio when the absolute value of the AC input voltage V _in is low, the switching signal with a reduced duty ratio when the absolute value of the AC input voltage V _in is high, the switching circuit SW It is output to the control pole of the switching element included in.

The control circuit 19, the AC input voltage V _in is in the half cycle when positive, the absolute value of the AC input voltage V _in is at greater than the first DC output voltage V _out1, outputs the switching signal Is preferable. On the other hand, in the half cycle when the AC input voltage V _in is negative, when the absolute value of the AC input voltage V _in is higher than the second DC output voltage V _out2, it is preferable to output the switching signal.

Even the switching circuit SW is turned on when the the switching signal is output absolute value of the AC input voltage V _in is smaller than the first DC output voltage V _out1 or second DC output voltage V _out2, first rectifying element D1 and second rectifying element D2 is, can prevent reverse current flow to the AC power supply PS from the first capacitor element C1 and the second capacitor element C2, the absolute value of the first DC output voltage _V of the AC input voltage _{V in out1} or by not outputting a switching signal when less than the second DC output voltage V _out2, can be avoided to unnecessarily operate the switching circuit SW.

[1-5-1. Operation when the AC input voltage is positive]

Hereinafter, the AC input voltage V _in is the operation of the AC-DC converter circuit 1 when positive. When an AC input voltage _{V in} is positive (VL> VN), the potential VL of the first input terminal I1 is higher than the potential _{V out1} + VN on the side connected to the inductor element L of the first capacitor element C1, The potential on the anode side of the first rectifying element D1 becomes larger than the potential (VN) on the cathode side. As a result, the first rectifying element D1 becomes conductive, and the first sub-AC / DC converter circuit 13 operates.

Meanwhile, when the AC input voltage V _in is positive, the anode side of the potential of the second rectifying element D2 (VN) is becomes smaller than the potential of the cathode side, the second rectifying element D2 becomes nonconductive. That is, the second sub-AC / DC converter circuit 15 stops operating.

_{When the switching circuit SW is turned on when the potential VL of the first input terminal I1 becomes higher than the potential V out1} + VN on the side connected to the inductor element L of the first capacitor element C1, the AC power supply PS is shown in the figure. As shown in 4A, from the first pole P1, (1) first input terminal I1, (2) switching circuit SW, (3) inductor element L, (4) first capacitor element C1, (5) first rectification. _{The input current i in} is passed through the element D1 and (6) the second input terminal I2 in order to the second pole P2. Since the inductor element L is present, _{the absolute value of the input current i in in} this case increases substantially linearly with time.

On the other hand, is positive AC input voltage V _in and the switching circuit SW when the absolute value thereof is larger than V _out1 is turned off, the inductor element L is disconnected from the AC power supply PS, AC power supply PS is input The current i _in is not output.

On the other hand, in a closed circuit formed by the inductor element L, the first capacitor element C1 and the third rectifying element D3, as shown in FIG. 4B, (1) the inductor element L and (2) the first capacitor element C1. , (3) The recirculation current flows in the order of the third rectifying element D3. This recirculation current flows due to the energy stored in the inductor element L while the switching circuit SW is in the ON state. When the above-mentioned recirculation current flows, the energy stored in the inductor element L is consumed, so that the recirculation current decreases with time.

When switching the on state and the off state of the switching circuit SW at high speed as described above, the input current i _in can be adjusted by adjusting the ratio between the time in the on state and the time in the off state. That is, the input current i _in can be adjusted by adjusting the duty ratio, and in particular, the input power factor can be improved by controlling the _{input current i in} so as to be proportional to the input voltage waveform.

Further, while the first capacitor element C1 is charged by the input current _in and the recirculation current, the electric charge accumulated in the first capacitor element C1 is consumed by the load LO through the second capacitor element C2. If the time average of the charge amount is larger than the time average of the load consumption, the potential difference (voltage) at both ends of the first capacitor element C1 increases, and if the time average of the charge charge amount is smaller than the time average of the load consumption, the potential difference (voltage) is increased. The potential difference (voltage) across the first capacitor element C1 decreases.

Therefore, the ratio between the time when the input current i _in flows and the time when it does not flow, that is, the duty ratio when the switching circuit SW switches between the on state and the off state at high speed, is the voltage generated across the first capacitor element C1. To decide.

By adjusting the duty ratio so that the input current waveform has a high power factor in the short term, and by adjusting the duty ratio so that the first DC output voltage V _{out 1} becomes almost constant in the long term time average. It is possible to perform AC / DC conversion control with a high power factor.

As shown in the lower figure of FIG. 6, the input current i output from the AC power supply PS during a period _in which the AC input voltage Vin of a half cycle _in which the AC input voltage Vin is positive is larger than the first DC output voltage V _out1. average of _in increases or decreases in response to an AC input voltage _{V in.} On the other hand, _in the other period of the half cycle _{in which the AC input voltage Vin is positive, the input current i in} becomes 0.

[1-5-2. Operation when the AC input voltage is negative]

Then, the AC input voltage V _in is the operation of the AC-DC converter circuit 1 when negative. When the AC input voltage _{V in} is negative (VL <VN), potential VN of the second input terminal I2 is higher than the second second side connected to the output terminal O2 potential _{V out2} + VL capacitor element C2 Then, the potential (VN) on the anode side of the second rectifying element D2 becomes larger than the potential on the cathode side. As a result, the second rectifying element D2 becomes a conductive state, and the second sub-AC / DC converter circuit 15 operates.

On the other hand, when the AC input voltage V _in is negative, since the cathode potential of the first rectifying element D1 (VN) is greater than the potential of the anode side, a first rectifier element D1 becomes non-conductive. That is, the first sub-AC / DC converter circuit 13 stops operating.

_{When the potential VN of the second input terminal I2 becomes higher than the potential V out2} + VL on the side connected to the second output terminal O2 of the second capacitor element C2, when the switching circuit SW is turned on, the AC power supply PS becomes As shown in FIG. 5A, from the second pole P2, (1) second input terminal I2, (2) second rectifying element D2, (3) second capacitor element C2, (4) inductor element L, (5). _{) The input current i in} flows through the switching circuit SW and (6) the first input terminal I1 in order to the first pole P1. Since the inductor element L is present, _{the absolute value of the input current i in in} this case increases substantially linearly with time.

On the other hand, when the switching circuit SW when the AC input voltage V _in is negative and is and the absolute value thereof is larger than V _out2 is turned off, the inductor element L is disconnected from the AC power supply PS, AC power supply PS is input The current i _in is not output.

On the other hand, in a closed circuit formed by the inductor element L, the fourth rectifying element D4, and the second capacitor element C2, as shown in FIG. 5B, (1) the inductor element L and (2) the fourth rectifying element D4. , (3) The recirculation current flows in the order of the second capacitor element C2. This recirculation current flows due to the energy stored in the inductor element L while the switching circuit SW is in the ON state. When the above-mentioned recirculation current flows, the energy stored in the inductor element L is consumed, so that the recirculation current decreases with time.

When switching the on state and the off state of the switching circuit SW at high speed as described above, the input current i _in can be adjusted by adjusting the ratio between the time in the on state and the time in the off state. That is, the input current i _in can be adjusted by adjusting the duty ratio, and in particular, the input power factor can be improved by controlling the _{input current i in} so as to be proportional to the input voltage waveform.

Further, while the second capacitor element C2 is charged by the input current _in and the recirculation current, the electric charge accumulated in the second capacitor element C2 is consumed by the load LO through the first capacitor element C1. If the time average of the charge amount is larger than the time average of the load consumption, the potential difference (voltage) at both ends of the second capacitor element C2 increases, and if the time average of the charge charge amount is smaller than the time average of the load consumption, the potential difference (voltage) is increased. The potential difference (voltage) across the second capacitor element C2 decreases.

Therefore, the ratio between the time when the input current i _in flows and the time when it does not flow, that is, the duty ratio when the switching circuit SW switches between the on state and the off state at high speed, is the voltage generated across the second capacitor element C2. To decide.

While adjusting the duty ratio so that the input current waveform is high power factor in the short term, as the average long-term time second DC output voltage V _out2 becomes substantially constant by adjusting the duty ratio, It is possible to perform AC / DC conversion control with a high power factor.

In the present embodiment, the AC input voltage V _in is the average value of the duty ratio of the positive case, the average value of the duty ratio when the AC input voltage V _in is negative, the same a. However, not limited thereto, and may be different from the average value of the duty ratio in the positive and negative of the AC input voltage V _in.

On the other hand, in a half cycle of the AC input voltage V _in is negative, the mean value of the input current i _in output from the AC power supply PS, as shown in the lower part of FIG. 6, in response to the AC input voltage V _in increased or decreased do. However, the absolute value of the AC input voltage _{V in} is at the time less than the second DC output voltage _{V out2,} the input current _{i in} does not flow.

As described above, in the AC / DC converter circuit 1 of the present embodiment, the first capacitor element C1 and the second capacitor element C2 are connected in series between the first output terminal O1 and the second output terminal O2. Therefore, a constant first DC output voltage V _out1 is generated in the first capacitor element C1, and a constant second DC output voltage V _out2 is generated in the second capacitor element C2. as shown in, over one period of the AC input voltage _{V in,} between the first output terminal O1 and the second output terminal O2, and a total of the first DC output voltage _{V out1} and a second DC output voltage _{V out2} A constant voltage (V _out1 + V _out2 ) can be output as the output voltage V _out.

In the above, when the AC input voltage V _in is positive, controls so that the time average value of the first DC output voltage V _out1 is substantially constant, when the AC input voltage is negative, the second DC output voltage time average value of the V _out2 stated a method of controlling so as to be substantially constant. However, as another method, the time average value of the output voltage V _out may be controlled to be substantially constant _{regardless of whether the AC input voltage V in is positive or negative.} In this _method, there is no need to monitor both the _{V out1} and _{V out2,} since it is sufficient only monitors _{V out,} it is possible to simplify the voltage detection circuit.

The first sub-AC-DC conversion circuit 13 and the second auxiliary AC-DC converter circuit 15 is a step-down chopper circuit, respectively, the maximum peak voltage of the AC input voltage V _in by equal first DC output voltage V _out1 and a second DC output The voltage V _out2 can be output. As a result, AC-DC converter circuit 1 according to the first embodiment, between the first output terminal O1 and the second output terminal O2, up to twice the DC voltage the output voltage of the peak voltage of the AC input voltage V _in It can be output as _{V out.}

The circuit capable of outputting a large DC voltage than the AC input voltage V _in, as described above, for example, a AC-DC converter of the step-up chopper. In the step-up chopper type AC / DC conversion circuit, the capacitor element connected in parallel to the output terminal is connected to the AC power supply via the inductor element. Therefore, when the AC power supply is turned on in the step-up chopper type AC / DC conversion circuit, an inrush current may flow from the AC power supply to the load connected to the capacitor element and / or the output terminal via the inductor element. In order to prevent the inrush current from flowing to the elements or loads constituting the circuit, a general step-up chopper type AC / DC conversion circuit has, for example, a thermistor for suppressing the inrush current.

On the other hand, in the first sub-AC / DC conversion circuit 13 and the second sub-AC / DC conversion circuit 15, which are step-down chopper circuits, as shown in FIG. 1, the inductor element L, the first capacitor element C1, and the second capacitor element C2 are It is connected to the AC power supply PS via the switching circuit SW. Therefore, in the first sub-AC / direct conversion circuit 13 and the second sub-AC / direct conversion circuit 15, inrush current flows through the inductor element L, the first capacitor element C1, and the second capacitor element C2 when the AC power supply PS is turned on. No.

Therefore, AC-DC converter circuit 1 according to the first embodiment, while avoiding the generation of inrush current without the need for elements for suppressing the inrush current, such as a thermistor, than the peak voltage of the AC input voltage V _in A high DC voltage can be output between the first output terminal O1 and the second output terminal O2.

Moreover, later as will be described in detail, in comparison with the AC-DC conversion circuit of a conventional step-down chopper and AC-DC converter circuit 1 according to the first embodiment, the same to the AC input voltage V _in having the same peak value When a DC voltage is output, the _{period during which the input current i in} flows in the AC / DC conversion circuit 1 is longer than the period during which the input current flows in the conventional step-down chopper type AC / DC conversion circuit.

This is because, first sub AC-DC converter circuit 13 and the second auxiliary AC-DC conversion circuit 15 for inputting the same AC input voltage _{V in,} the output voltage _{V out} and the first DC output voltage _{V out1} to the second DC output voltage _{V out2} This is because the voltage is divided. As a result, the AC input for one cycle of the voltage _{V in,} AC-DC converter circuit AC input voltage _{V in} is the first DC output voltage _{V out1} or second DC output voltage _V larger time than _out2 in the first embodiment the is because the AC input voltage _{V in} the AC-DC conversion circuit of a conventional step-down chopper can be longer than the larger time than the output voltage _{V out (V out1 + V out2} ).

As described above, since the input current i _in increases / decreases in response to the increase / decrease _in the AC input voltage Vin, the AC / DC conversion circuit 1 according to the first embodiment is input by allowing the _{input current i in to flow for a longer period of time.} The waveform of the current i _in can be made closer to the waveform of the AC input voltage V _in. That is, when the same output voltage is output for the same input voltage, the AC / DC conversion circuit 1 according to the first embodiment can operate at a higher power factor than the conventional step-down chopper type AC / DC conversion circuit.

(2. Comparative example)

Hereinafter, the AC-DC conversion circuit of a general step-down chopper type as shown in FIG. 8, enter the same AC input voltage V _in to that described in the first embodiment, the same magnitude of the output voltage V _{out1 +} V The operation when outputting _{out2 will be described.}

AC-DC conversion circuit of the step-down chopper type shown in Figure 8, connected to the 'bridge diode BD full-wave rectifying an AC input voltage V _in the output' AC power supply PS, the 'bridge diode BD through the' switching circuit SW The inductor element L', the capacitor element C'in which one end is connected to the first output terminal O1'and the other end is connected to the second output terminal O2', and the anode side is connected to the first output terminal O1'and the cathode side is connected. It has a rectifying element D'connected between the inductor element L'and the switching circuit SW'.

In AC-DC converter of the step-down chopper type shown in FIG. 8, DC _V out1 _{+ V out2} between 'is input to the first output terminal O1' AC input voltage _{V in} the bridge diode BD and the second output terminal O2 ' when outputting the output voltage, as shown in the figure below, bold and solid line in FIG. 9, the input current flows when the absolute value of the AC input voltage V _in is greater than V _{out1 +} V _out2.

Accordingly, the AC-DC converter of the step-down chopper type shown in FIG. 8, the ratio for one period of the AC input voltage V _in of the time the input current flows is smaller than the AC-DC converter circuit 1 according to the first embodiment. As a result, the waveform of the input current flowing in the step-down chopper type AC / DC conversion circuit shown in FIG. 8 is the waveform of the input current i _in flowing in the AC / DC conversion circuit 1 according to the first embodiment (shown by a dotted line in the lower figure of FIG. 9). ) than, are far from the AC input voltage _{V in.} That is, when the same output voltage is output for the same input voltage, the power factor in the step-down chopper type AC / DC conversion circuit shown in FIG. 8 is lower than the power factor of the AC / DC conversion circuit 1 according to the first embodiment. It has become.

(3. Embodiment 2)

In the first embodiment described above, the switching circuit SW is shared by the first sub-AC / DC converter circuit 13 and the second sub-AC / DC converter circuit 15. Therefore, the AC / DC converter circuit 1 according to the first embodiment includes only one switching circuit SW. However, the present invention is not limited to this, and switching elements may be individually provided for the first sub-AC / DC converter circuit 13 and the second sub-AC / DC converter circuit 15.

Specifically, as shown in FIG. 10, the AC / DC converter circuit 2 according to the second embodiment includes a switching circuit SW ″ having a first switching element SW1 and a second switching element SW2 connected in series. Further, the switching circuit SW ″ has a fifth rectifying element D5 connected in parallel to the first switching element SW1 and a sixth rectifying element D6 connected in parallel to the second switching element SW2.

In the fifth rectifying element D5, one end on the anode side is connected between the first switching element SW1 and the second switching element SW2, and the other end on the cathode side is connected to the first input terminal I1 of the first switching element SW1. Connect to the other side. In the sixth rectifying element D6, one end on the anode side is connected between the first switching element SW1 and the second switching element SW2, and the other end on the cathode side is connected to the inductor element L of the second switching element SW2. Connect to. As a result, as shown in FIG. 10, the anode side of the fifth rectifying element D5 and the anode side of the sixth rectifying element D6 are commonly connected between the first switching element SW1 and the second switching element SW2. ..

The fifth rectifying element D5 and the sixth rectifying element D6 may be individual elements (for example, diodes), respectively, or the rectifying element (main body) formed inside the first switching element SW1 and the second switching element SW2. It may be called a diode, a parasitic diode, or the like). When the first switching element SW1 and the second switching element SW2 are µ-FETs, the anode side of the fifth rectifying element D5 and the anode side of the sixth rectifying element D6 are the source poles of the first switching element SW1, respectively. And connected to the source electrode of the second switching element SW2. As a result, the source poles of the first switching element SW1 and the second switching element SW2 are connected to the common node.

Therefore, by connecting the anode side of the fifth rectifying element D5 and the anode side of the sixth rectifying element D6 in common between the first switching element SW1 and the second switching element SW2, the first switching element SW1 and the first switching element SW1 and the second switching element SW2 are connected in common. The gate drive power supply of the second switching element SW2 can be shared. This is because, by connecting the source electrode of the first switching element SW1 and the source electrode of the second switching element SW2 in common, the ground of the gate drive power supply can be shared by the first switching element SW1 and the second switching element SW2. Because.

In the switching circuit SW'' shown in FIG. 10, contrary to the above, the cathode side of the fifth rectifying element D5 and the cathode side of the sixth rectifying element D6 are between the first switching element SW1 and the second switching element SW2. May be connected in common. In this case, the connection order of the first switching element SW1 and the second switching element SW2 may be reversed from the case shown in FIG. Specifically, the second switching element SW2 may be arranged closer to the first input terminal I1 than the first switching element SW1.

In the second embodiment, when the first sub-AC / DC conversion circuit 13 is operated, that is, when the potential VL of the first input terminal I1 is higher than the potential VN of the second input terminal I2, the control circuit 19 is the first switching. The ON state and the OFF state of the element SW1 are switched at high speed by PWM control. On the other hand, when the second sub-AC / DC conversion circuit 15 is operated, that is, when the potential VL of the first input terminal I1 is lower than the potential VN of the second input terminal I2, the on state and the off state of the second switching element SW2 are set. Is switched at high speed by PWM control.

In the above switching circuit SW'', while switching between the on state and the off state of one switching element, the other switching element may maintain the on state or may maintain the off state. ..

When the first switching element SW1 when the AC input voltage _{V in} is positive (VL> VN) is turned on, when the second switching element SW2 is kept off, the first switching element SW1 sixth rectifier An input current i _in flows through the element D6. On the other hand, when the second switching element SW2 is maintained in the ON state, an input current i _in flows through the first switching element SW1 and the second switching element SW2.

On the other hand, when the AC input voltage _{V in} the second switching element SW2 is turned on when a negative (VL <VN), when the first switching element SW1 maintains the OFF state, the second switching element SW2 first 5 An input current i _in flows through the rectifying element D5. On the other hand, when the first switching element SW1 is maintained in the ON state, an input current i _in flows through the second switching element SW2 and the first switching element SW1.

As described above, it is generated by the _{input current i in} flowing through the 5th rectifying element D5 or the 6th rectifying element D6 by keeping the other switching element in the ON state while one switching element is PWM controlled. Conduction loss can be reduced.

The other case that maintains the switching element in the ON state, after the AC input voltage V _in a predetermined reaching the zero crossing point time or AC input voltage V _in is passed through the zero-crossing point during the PWM control one of the switching elements After that, it is preferable to turn on the state when a predetermined voltage is reached and turn off the state before reaching the next zero cross point. As a result, even if an error occurs in the detection of the zero cross point, it is possible to prevent a malfunction such as starting the on state before reaching the zero cross point and / or ending the on state after reaching the zero cross point.

In the switching circuit SW'', the fifth rectifying element D5 is connected in parallel to both ends electrically connected or disconnected by the switching operation of the first switching element SW1, and is electrically connected or electrically connected by the switching operation of the second switching element SW2. by paralleling sixth rectifying element D6 at both ends are cut, in the zero-crossing point near the AC input voltage V _in, input current i _in, the flow through the fifth rectifying element D5 or sixth rectifying element D6 be able to. As a result, the zero-cross point of AC input voltage V _in, it provides smooth control of the AC-DC conversion circuit 2.

The "both ends electrically connected or disconnected by the switching operation" of the first switching element SW1 and the second switching element SW2 are defined as "both ends electrically connected or disconnected by the switching operation" when the first switching element SW1 and the second switching element SW2 are MOSFETs. It refers to the source pole and drain pole of these switching elements.

(4. Embodiment 3)

In the third embodiment, the AC / DC converter circuit 3 may further include a third switching element SW3 and a fifth switching element SW5, as shown in FIG. In the third switching element SW3, one end of both ends electrically connected or disconnected by the switching operation is connected to the first output terminal O1, and the other end is connected to the anode side of the third rectifying element D3. That is, the third switching element SW3 is connected in series to the third rectifying element D3 between the inductor element L and the first output terminal O1. Control circuit 19, in the second sub-AC-DC conversion circuit 15 is operating, i.e., when the AC input voltage V _in is negative, and turns off the third switching element SW3.

On the other hand, in the fifth switching element SW5, one end of both ends electrically connected or disconnected by the switching operation is connected to the second output terminal O2, and the other end is connected to the cathode side of the fourth rectifying element D4. That is, the fifth switching element SW5 is connected in series to the fourth rectifying element D4 between the inductor element L and the second output terminal O2. Control circuit 19, during the first sub-AC-DC conversion circuit 13 is operating, i.e., the AC input voltage V _in is at the positive, and turns off the fifth switching device SW5.

By providing the third switching element SW3 of the the fifth switching element SW5, AC-DC converter circuit 3, between the first output terminal O1 and the second output terminal O2, the absolute value of the AC input voltage V _{in An output voltage V out} smaller than the peak value can be output.

Hereinafter, as an example, the AC-DC converter circuit without a third switching element SW3 of the fifth switching device SW5, consider the case where than the peak value of the absolute value of the AC input voltage V _in and outputs a small output voltage V _out. During the first sub-AC-DC conversion circuit 13 is an AC input voltage _{V in} is positive (VL> VN) operation, the first pole P1 potential VL is the potential of the second output terminal O2 of the AC power source PS _(V out + VN) When it becomes larger than, a current flows through the fourth rectifying element D4 to charge the second capacitor element C2. As a result, the absolute value voltage lower than the peak value of the AC input voltage V _in, it can not be output between the first output terminal O1 and the second output terminal O2.

On the other hand, during the second sub-AC-DC conversion circuit 15 AC input voltage _{V in} is negative (VL <VN) operation, the potential VL of the first pole P1 is higher than the potential _{(VN-V out)} to a first output terminal O1 When it becomes smaller, a current flows through the third rectifying element D3 to charge the first capacitor element C1. As a result, the absolute value voltage lower than the peak value of the AC input voltage V _in, it can not be output between the first output terminal O1 and the second output terminal O2.

Accordingly, the AC-DC converter circuit 3 according to the third embodiment, since the first sub-AC-DC conversion circuit 13 is positive AC input voltage V _in to the fifth switching element SW5 turned off during operation, the first pole It is possible to avoid a current flowing through the fourth rectifying element D4 when the potential VL of P1 becomes _{larger than V out + VN.} Further, since the second sub-AC-DC conversion circuit 15 AC input voltage _{V in} is negative to the third switching element SW3 turned off during operation, the potential VL of the first pole P1 is smaller than the _{VN-V out} It is possible to avoid a current flowing through the third rectifying element D3 when the voltage becomes high.

When the potential VL of the first pole P1 becomes _{larger than V out} + VN, no current flows through the fourth rectifying element D4, and _{when it becomes smaller than VN −V out} , a current flows through the third rectifying element D3. By not flowing, the first capacitor element C1 and the second capacitor element C2 are prevented from being charged by a path other than the inductor element L, and an alternating current is provided between the first output terminal O1 and the second output terminal O2. _{An output voltage V out} smaller than the peak value of the absolute value of the input voltage V _in can be output.

As shown in FIG. 11, the seventh rectifying element D7 may be connected in parallel to the third switching element SW3, and the eighth rectifying element D8 may be connected in parallel to the fifth switching element SW5. .. In this case, the 7th rectifying element D7 and the 8th rectifying element D8 may be individual elements, respectively, or the rectifying element (parasitic diode, parasitic diode, which is formed inside the 3rd switching element SW3 and the 5th switching element SW5, respectively. It may be a main body diode).

Further, as long as the third rectifying element D3 and the third switching element SW3 are connected in series, the connection relationship may be opposite to that in FIG. That is, the anode side of the third rectifying element D3 may be connected to the first output terminal O1, the cathode side may be connected to one end of the third switching element SW3, and the other end of the third switching element SW3 may be connected to the inductor element L. ..

Similar to the above, as long as the fourth rectifying element D4 and the fifth switching element SW5 are connected in series, the connection relationship may be opposite to that in FIG. That is, even if the cathode side of the fourth rectifying element D4 is connected to the second output terminal O2, the anode side is connected to one end of the fifth switching element SW5, and the other end of the fifth switching element SW5 is connected to the inductor element L. good.

Further, the third switching element SW3 and the fifth switching element SW5 are switched at a lower speed than the switching circuit SW of the first embodiment and / or the first switching element SW1 and the second switching element SW2 of the second embodiment. Operation may be possible. By using a switching element that operates at a low speed as the third switching element SW3 and the fifth switching element SW5, the AC / DC conversion circuit 3 can be made inexpensive.

(5. Embodiment 4)

In the fourth embodiment, the AC / DC converter circuit 4 may further include a fourth switching element SW4 and a sixth switching element SW6, as shown in FIG. In the fourth switching element SW4, one end of both ends electrically connected or disconnected by the switching operation is connected to the anode side of the third rectifying element D3, and the other end is connected to the cathode side of the third rectifying element D3. .. That is, the fourth switching element SW4 is connected in parallel to the third rectifying element D3.

In the sixth switching element SW6, one end of both ends electrically connected or disconnected by the switching operation is connected to the anode side of the fourth rectifying element D4, and the other end is connected to the cathode side of the fourth rectifying element D4. .. That is, the sixth switching element SW6 is connected in parallel to the fourth rectifying element D4.

In AC-DC converter circuit 4 according to the fourth embodiment, the control circuit 19, the potential VL of the first input terminal I1 is higher than the potential VN of the second input terminal I2, i.e., the AC input voltage V _in is positive Occasionally, the fourth switching element SW4 is turned on at a predetermined timing after the first switching element SW1 has transitioned from the on state to the off state. Further, the fourth switching element SW4 is turned off at a predetermined timing before the first switching element SW1 transitions from the off state to the on state.

Thus, the first sub-AC-DC conversion circuit 13 is operating when the AC input voltage V _in is positive, the first switching element SW1 is turned off, the inductor element L, a first capacitor element C1, the third rectifier When a recirculation current flows through the closed circuit formed by the element D3 (fourth switching element SW4), the recirculation current passes through the fourth switching element SW4. As a result, the conduction loss generated by the recirculation current flowing through the third rectifying element D3 can be reduced.

On the other hand, the control circuit 19, when the potential VL of the first input terminal I1 is lower than the potential VN of the second input terminal I2, i.e., when the AC input voltage _{V in} is negative, the second switching element SW2 is turned on The sixth switching element SW6 is turned on at a predetermined timing after the transition from the state to the off state. Further, the sixth switching element SW6 is turned off at a predetermined timing before the second switching element SW2 transitions from the off state to the on state.

Thus, the second sub-AC-DC conversion circuit 15 is operating when the AC input voltage V _in is negative, the second switching element SW2 is turned off, the inductor element L, and the second capacitor element C2, the fourth rectifier When a recirculation current flows through the closed circuit formed by the element D4 (sixth switching element SW6), the recirculation current passes through the sixth switching element SW6. As a result, the conduction loss generated by the recirculation current flowing through the fourth rectifying element D4 can be reduced.

In the AC / DC conversion circuit 4, the third rectifying element D3 and the fourth rectifying element D4 may be individual elements (for example, diodes), respectively, or inside the fourth switching element SW4 and the sixth switching element SW6. It may be a rectifying element (main body diode, parasitic diode) formed in.

(6. Embodiment 5)

In the fifth embodiment, the AC / DC converter circuit 5 may further include a seventh switching element SW7 and an eighth switching element SW8, as shown in FIG. In the seventh switching element SW7, one end of both ends electrically connected or disconnected by the switching operation is connected to the anode side of the first rectifying element D1, and the other end is connected to the cathode side of the first rectifying element D1. .. That is, the seventh switching element SW7 is connected in parallel to the first rectifying element D1.

In the eighth switching element SW8, one end of both ends electrically connected or disconnected by the switching operation is connected to the anode side of the second rectifying element D2, and the other end is connected to the cathode side of the second rectifying element D2. .. That is, the eighth switching element SW8 is connected in parallel to the second rectifying element D2.

In AC-DC conversion circuit 5 according to the fifth embodiment, the control circuit 19, the potential VL of the first input terminal I1 is higher than the potential VN of the second input terminal I2, i.e., becomes the AC input voltage V _in is positive, The seventh switching element SW7 is turned on at a predetermined timing after the first rectifying element D1 changes from the non-conducting state to the conducting state. Further, at a predetermined timing before the potential VL of the first input terminal I1 becomes lower than the potential VN of the second input terminal I2 and the first rectifying element D1 changes from the conductive state to the non-conducting state, the seventh switching element SW7 Is turned off.

Thus, the AC input voltage V _in during the first sub-AC-DC converter circuit 13 when the positive operating, the input current i _in passes through the seventh switching element SW7. As a result, _{the conduction loss generated by the input current i in} flowing through the first rectifying element D1 can be reduced.

On the other hand, the control circuit 19, the potential VL of the first input terminal I1 is lower than the potential VN of the second input terminal I2, i.e., the AC input voltage V _in is negative, the second rectifying element D2 is from a non-conductive state The eighth switching element SW8 is turned on at a predetermined timing after the conduction state is reached. Further, at a predetermined timing before the potential VL of the first input terminal I1 becomes higher than the potential VN of the second input terminal I2 and the second rectifying element D2 changes from the conductive state to the non-conducting state, the eighth switching element SW8 Is turned off.

Thus, the second sub-AC-DC conversion circuit 15 is operating when the AC input voltage V _in is negative, the input current i _in is passed through the eighth switching device SW8. As a result, _{the conduction loss generated by the input current i in} flowing through the second rectifying element D2 can be reduced.

By having the 7th switching element SW7 and the 8th switching element SW8 described above, the AC / DC conversion circuit 5 has the second input terminal I2, that is, the second AC power supply PS while the first sub-AC / DC conversion circuit 13 is in operation. The pole P2 and the first output terminal O1 can be in a conductive state, and the second pole P2 and the second output terminal O2 of the AC power supply PS can be in a conductive state while the second sub-AC / DC conversion circuit 15 is in operation. As a result, the potentials of the first output terminal O1 and the second output terminal O2 can be stabilized and the generation of noise can be suppressed.

As shown in FIG. 13, by connecting switching elements in parallel to each rectifying element constituting the AC / DC conversion circuit 5, it is possible to reduce conduction loss due to current flowing through the rectifying element in the entire AC / DC conversion circuit 5.

In AC-DC conversion circuit 5 according to Embodiment 5 of the above embodiments, the AC input voltage V _in during the positive next first sub AC-DC converter circuit 13 is operating, the AC input voltage V _in is the voltage across the first capacitor element C1 If it is less than, either the second switching element SW2 or the seventh switching element SW7 is turned off. Thus, alternating current when the input voltage V _in falls below the voltage across the first capacitor element C1, the first switching element SW1 is first input terminal of the first capacitor element C1 in spite of the OFF state I1 It is possible to avoid the flow of reverse current in the direction toward.

On the other hand, when the second sub-AC-DC conversion circuit 15 becomes the AC input voltage V _in is negative is during operation, the absolute value of the AC input voltage V _in falls below the voltage across the second capacitor element C2, the first Either the switching element SW1 or the eighth switching element SW8 is turned off. Thus, when the absolute value of the AC input voltage V _in falls below the voltage across the second capacitor element C2, the second switching element SW2 is first input terminal I1 despite the off-state second It is possible to avoid a reverse current flowing in the direction toward the capacitor element C2.

(7. Embodiment 6)

In the above embodiments 1 to 5, the inductor element L is shared by the first sub-AC / DC converter circuit 13 and the second sub-AC / DC converter circuit 15. Therefore, the AC / DC converter circuits 1 to 5 according to the first to fifth embodiments include only one inductor element L. However, the present invention is not limited to this, and as shown in FIG. 14, inductor elements may be individually provided for the first sub-converter-to-transverse conversion circuit 13'and the second sub-account-to-transverse conversion circuit 15'. In this case, the first sub-AC / DC converter circuit 13'and the second sub-AC / DC converter circuit 15'conform an independent step-down chopper circuit, respectively.

Specifically, the first sub-AC / converter conversion circuit 13'has a first switching element SW1', a first inductor element L1, a first capacitor element C1', a first rectifying element D1', and a third rectifying element. It has D3'and. The first switching element SW1'connects one end of both ends electrically connected or disconnected by the switching operation to the first input terminal I1. The first inductor element L1 connects the other end of the first switching element SW1'on the side opposite to the side connected to the first input terminal I1.

One end of the first capacitor element C1'is connected to the other end of the first inductor element L1 opposite to the side connected to the first switching element SW1', and the other end is connected to the first output terminal O1. In the first rectifying element D1', the anode side is connected to the first output terminal O1 and the cathode side is connected to the second input terminal I2.

The second sub-AC / converter conversion circuit 15'contains the second switching element SW2', the second inductor element L2, the second capacitor element C2', the second rectifying element D2', and the fourth rectifying element D4'. Have. The second switching element SW2'connects one end of both ends electrically connected or disconnected by the switching operation to the first input terminal I1. The second inductor element L2 connects the other end of the second switching element SW2'on the side opposite to the side connected to the first input terminal I1.

One end of the second capacitor element C2'is connected to the other end of the second inductor element L2 on the opposite side to the side connected to the second switching element SW2'. Further, the one end of the second capacitor element C2'is connected to the first capacitor element C1'. The other end of the second capacitor element C2'is connected to the second output terminal O2. As a result, the first capacitor element C1'and the second capacitor element C2' are connected in series between the first output terminal O1 and the second output terminal O2.

The second rectifying element D2'connects the cathode side to the second output terminal O2 and the anode side to the second input terminal I2.

In the AC / DC conversion circuit 6 having the above configuration, the control circuit (not shown in FIG. 14) is subjected to PWM control when the potential VL of the first input terminal I1 is higher than the potential VN of the second input terminal I2. The on state and the off state of the first switching element SW1'are switched. As a result, the first sub-AC / DC converter circuit 13'operates.

Specifically, when the potential VL of the first input terminal I1 is higher than the potential VN of the second input terminal I2 and the first switching element SW1'is turned on, (1) the first input terminals I1 and (2) ) First switching element SW1', (3) first inductor element L1, (4) first capacitor element C1', (5) first rectifying element D1', (6) second input terminal I2 in this order. _in flows. On the other hand, when the first switching element SW1'is in the off state, a circulating current flows in the closed circuit composed of the first inductor element L1, the first capacitor element C1', and the third rectifying element D3'. The absolute value of the recirculation current decreases with time.

When switching the on state and the off state of the first switching element SW1'at high speed as described above, the input current i _in can be adjusted by adjusting the ratio between the time in the on state and the time in the off state. .. _{In particular, if the input current i in} is controlled so as to be proportional to the input voltage waveform, the input power factor can be improved.

Further, while the first capacitor element C1'is charged by the above input current _in and the recirculation current, the electric charge accumulated in the first capacitor element C1'is consumed by the load LO through the second capacitor element C2'. To. If the time average of the charge amount is larger than the time average of the load consumption, the potential difference (voltage) at both ends of the first capacitor element C1'increases, and if the time average of the charge charge amount is smaller than the time average of the load consumption. , The potential difference (voltage) across the first capacitor element C1'decreases.

Therefore, the ratio of the time when the input current i _in flows to the time when it does not flow, that is, the duty ratio when the first switching element SW1'switches between the on state and the off state at high speed is both ends of the first capacitor element C1'. Determine the voltage generated in.

Adjust the duty ratio so that the input current waveform has a high power factor in the short term, and adjust the duty ratio so that the voltage V _{out 1'of} the first capacitor element C1'is almost constant in the long term time average. By doing so, it is possible to perform AC / DC conversion control with a high power factor.

On the other hand, when the potential VL of the first input terminal I1 is lower than the potential VN of the second input terminal I2, the control circuit switches between the on state and the off state of the second switching element SW2'by PWM control. As a result, the second sub-AC / DC converter circuit 15'operates.

Specifically, when the potential VL of the first input terminal I1 is lower than the potential VN of the second input terminal I2 and the second switching element SW2'is turned on, (1) the second input terminals I2, (2). ) Second rectifying element D2', (3) second capacitor element C2', (4) second inductor element L2, (5) second switching element SW2', (6) first input terminal I1 in this order. _in flows. On the other hand, when the second switching element SW2'is in the off state, a circulating current flows in the closed circuit composed of the second inductor element L2, the second capacitor element C2', and the fourth rectifying element D4'. The absolute value of the recirculation current decreases with time.

When switching the on state and the off state of the second switching element SW2'at high speed as described above, the input current i _in can be adjusted by adjusting the ratio between the time in the on state and the time in the off state. .. _{In particular, if the input current i in} is controlled so as to be proportional to the input voltage waveform, the input power factor can be improved.

Further, while the second capacitor element C2'is charged by the above input current _in and the recirculation current, the electric charge accumulated in the second capacitor element C2'is consumed by the load LO through the first capacitor element C1'. To. If the time average of the charge amount is larger than the time average of the load consumption, the potential difference (voltage) at both ends of the second capacitor element C2'increases, and if the time average of the charge charge amount is smaller than the time average of the load consumption. , The potential difference (voltage) at both ends of the second capacitor element C2'decreases.

Therefore, the ratio of the time when the input current i _in flows to the time when it does not flow, that is, the duty ratio when the second switching element SW2'switches between the on state and the off state at high speed is both ends of the second capacitor element C2'. Determine the voltage generated in.

Adjust the duty ratio so that the input current waveform has a high power factor in the short term, and adjust the duty ratio so that the voltage V out _2'of the second capacitor element C2'is almost constant in the long term time average. By doing so, it is possible to perform AC / DC conversion control with a high power factor.

As described above, since the first capacitor element C1'and the second capacitor element C2' are connected in series between the first output terminal O1 and the second output terminal O2, the AC / DC conversion circuit 6 is the first. A constant voltage V _out1 '+ V _out2 ', _{which is the sum of the voltage V out1'of the first capacitor element C1'and the voltage V out2} ' of the second capacitor element _{C2'between the} output terminal O1 and the second output terminal O2. Can be output as the output voltage V _out'.

In the above, when the AC input voltage V _in is positive, controls so that the time average value of the first DC output voltage V _{out1 'is} substantially constant, when the AC input voltage V _in is negative, the second A method of controlling the DC output voltage V out _{2'so that} the time average value is almost constant has been described. However, as another method, irrespective of the polarity of the AC input voltage V _in, the time average value of the output voltage V _{out 'may} be controlled to be substantially constant. In this method, there is no need to monitor both the _'voltage V _{out2 and'} voltage V _out1, since it is sufficient only monitors the voltage V _{out ',} it is possible to simplify the voltage detection circuit.

(7. Other embodiments)

As described above, the above-described embodiment has been described as an example of the technology disclosed in the present application. However, the technique in the present disclosure is not limited to this, and it is possible to make changes, replacements, additions, combinations of a plurality of embodiments, omissions, and the like as appropriate. Therefore, other embodiments will be exemplified below.

[1] The AC power supply PS is not limited to a single-phase AC power supply, but may be a three-phase AC power supply having three poles. In this case, the AC power supply PS may connect two of the three poles to the first input terminal I1 and the second input terminal I2 of the AC / DC converter circuits 1-6.

1-6 AC / DC converter circuit

11 Input section

I1 1st input terminal

I2 2nd input terminal

13, 13'First sub-converter-converter circuit

C1, C1'First capacitor element

L1 1st inductor element

D1, D1'First rectifying element

D3, D3'Third rectifying element

D5 5th rectifying element

D7 7th rectifying element

SW3 3rd switching element

SW4 4th switching element

SW7 7th switching element

15, 15'Second sub-converter / direct conversion circuit

C2, C2'2nd capacitor element

L2 2nd inductor element

D2, D2'Second rectifying element

D4, D4'4th rectifying element

D6 6th rectifying element

D8 8th rectifying element

SW5 5th switching element

SW6 6th switching element

SW8 8th switching element

17 Output section

O1 1st output terminal

O2 2nd output terminal 19 Control circuit

L inductor element

SW switching circuit

LO load

PS AC power supply

P1 1st pole

P2 2nd pole

SW', SW'' switching circuit

SW1, SW1'First switching element

SW2, SW2'Second switching element

V _in AC input voltage

V _out output voltage

V _out1 1st DC output voltage

V _out2 2nd DC output voltage

i _in input current

Claims (13)

An input unit having a first input terminal and a second input terminal,

An output unit having a first output terminal and a second output terminal,

An inductor element that connects one end to the first input terminal via a switching circuit, a first capacitor element that connects one end to the other end of the inductor element and the other end to the first output terminal, and a cathode side. A first sub-converter / direct conversion circuit having a first rectifying element having one end connected to the second input terminal and the other end on the anode side connected to the first output terminal.

The inductor element, the switching circuit, a second capacitor element having one end connected to the other end of the inductor element and the other end connected to the second output terminal, and one end on the anode side to the second input terminal. A second sub-converter / direct conversion circuit having a second rectifying element which is connected and the other end on the cathode side is connected to the second output terminal.

The AC / DC converter circuit. The switching circuit is

When an AC input voltage whose potential at the first input terminal is higher than the potential at the second input terminal is input to the input unit, the first sub-AC / DC conversion circuit is switched between an on state and an off state at high speed. The first switching element to operate and

When an AC input voltage whose potential of the first input terminal is lower than the potential of the second input terminal is input to the input unit, the on state and the off state are switched at high speed to form the second sub-AC / DC conversion circuit. The second switching element to operate and

The AC / DC converter circuit according to claim 1. The AC / DC conversion circuit according to claim 1 or 2, wherein the first sub-AC / DC conversion circuit and the second sub-AC / DC conversion circuit share the inductor element. The first sub-AC / DC converter further includes a third rectifying element in which one end on the cathode side is connected to the one end of the inductor element and the other end on the anode side is connected to the first output terminal. The AC / DC conversion circuit according to any one of 3. The AC / DC converter according to claim 4, wherein the first sub-AC / converter conversion circuit further includes a third switching element which is connected in series with the third rectifying element and is turned off during the operation of the second sub-AC / DC converter. circuit. The AC / DC converter according to claim 4, wherein the first sub-AC / converter conversion circuit further includes a fourth switching element connected in parallel to the third rectifier element. When the potential of the first input terminal is higher than the potential of the second input terminal, the fourth switching element is turned on at a predetermined timing after the switching circuit transitions from the on state to the off state. The AC / DC conversion circuit according to claim 6, wherein the switching circuit is turned off at a predetermined timing before the switching circuit transitions from the off state to the on state. The second sub-AC / DC converter circuit further includes a fourth rectifying element in which one end on the anode side is connected to the one end of the inductor element and the other end on the cathode side is connected to the second output terminal. 7. The AC / DC converter circuit according to any one of 7. The AC / DC converter according to claim 8, further comprising a fifth switching element which is connected in series with the fourth rectifying element and is turned off during the operation of the first sub-AC / DC converter. circuit. The AC / DC converter according to claim 8, wherein the second sub-AC / converter conversion circuit further includes a sixth switching element connected in parallel to the fourth rectifier element. When the potential of the first input terminal is lower than the potential of the second input terminal, the sixth switching element is turned on at a predetermined timing after the switching circuit transitions from the on state to the off state. The AC / DC conversion circuit according to claim 10, wherein the switching circuit is turned off at a predetermined timing before the switching circuit transitions from the off state to the on state. The AC / DC conversion circuit according to any one of claims 1 to 11, further comprising a seventh switching element connected in parallel to the first rectifying element. The AC / DC conversion circuit according to any one of claims 1 to 12, further comprising an eighth switching element connected in parallel to the second rectifying element.

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