JP6231400B2 - AC / DC converter and electric device equipped with the same - Google Patents

Description

  The present invention relates to an AC / DC converter that converts an AC voltage into a DC voltage, and an electrical apparatus including the same.

  In the conventional general AC / DC converter, since the output of the rectifying and smoothing circuit is one, the current conduction condition is limited when the AC voltage as the input voltage is lower than the DC voltage as the output voltage.

JP 2009-261077 A

  For this reason, in the conventional general AC / DC converter, there has been a limit in improving the power factor when the AC voltage as the input voltage is lower than the DC voltage as the output voltage. In addition, although the direct-current voltage which is an output voltage can be changed by providing the short circuit for a boost and a reactor, the cost increase and enlargement of an alternating current direct current converter will be caused.

  Patent Document 1 proposes an AC / DC converter in which a full-wave rectification method and a voltage doubler rectification method can be switched and two output capacitors are connected in series. In the AC / DC converter proposed in Patent Document 1, since the output voltage is always the voltage across the series circuit composed of two output capacitors, the AC voltage that is the input voltage is the same as that of the conventional general AC / DC converter. There is a limit to the improvement of the power factor when the voltage is lower than the DC voltage as the output voltage.

  An object of this invention is to provide the alternating current direct current converter which can suppress a power factor fall, and can perform highly efficient conversion operation, and an electric equipment provided with the same in view of said situation.

  In order to achieve the above object, an AC / DC converter according to the present invention is an AC / DC converter including a plurality of rectifying / smoothing circuits, wherein the plurality of rectifying / smoothing circuits are connected in parallel, A load connected to the output side of the AC / DC converter, comprising first switching means capable of turning on / off electrical connection between an AC power source connected to the input side and at least the first rectifying / smoothing circuit And at least a second switching means capable of turning on / off electrical connection with the first rectifying / smoothing circuit, and the first rectifying / smoothing circuit is included in the plurality of rectifying / smoothing circuits. The configuration (first configuration) is assumed.

  In the AC / DC converter having the first configuration, the first switching unit includes an AC power source connected to an input side of the AC / DC converter, the first rectifying / smoothing circuit, and the second rectifying / smoothing circuit. Electrical connection with each can be turned on / off, and the second switching means includes a load connected to the output side of the AC / DC converter, the first rectifying / smoothing circuit, and the second Electrical connection with each of the rectifying / smoothing circuits can be turned on / off, the second rectifying / smoothing circuit is included in the plurality of rectifying / smoothing circuits, and the first rectifying / smoothing circuit is a full-wave rectifying system. A configuration in which the second rectifying / smoothing circuit uses a voltage doubler rectification method (second configuration) is preferable.

  In the AC / DC converter having the first or second configuration, the first switching means is a semiconductor switch provided in the first rectifying / smoothing circuit and a semiconductor switch provided in the second rectifying / smoothing circuit. (3rd structure) containing is preferable. For example, a triac, a thyristor, or a transistor can be used as the semiconductor switch. When a bidirectional semiconductor switch such as a triac or a transistor is used as a rectifying element, it may be controlled so that the bidirectional semiconductor switch is always turned off in a half cycle corresponding to the reverse direction.

  In the AC to DC converter having any one of the first to third configurations, a configuration (fourth configuration) including a power factor correction circuit is preferable. Examples of the power factor correction circuit include (i) reactor only, (ii) simple PAM system using reactor and switching element, (iii) active filter system using reactor and switching element in the full wave region, (iv ) Interleave method using active filter method in parallel can be used.

  In the AC to DC converter of any of the first to fourth configurations, electrical connection with an AC power source connected to the input side of the AC to DC converter is always on, and the output of the AC to DC converter A configuration (fifth configuration) in which a third rectifying and smoothing circuit in which electrical connection with a load connected to the side is always on is included in the plurality of rectifying and smoothing circuits may be employed.

  In the AC / DC converter of any one of the first to fifth configurations, the first switching means includes a plurality of semiconductor switches that are connected in parallel and have different loss characteristics, and / or A configuration (sixth configuration) in which the two switching units are connected in parallel and each have a plurality of semiconductor switches having different loss characteristics is preferable.

  In order to achieve the above object, an electrical apparatus according to the present invention includes an AC / DC converter having any one of the first to sixth configurations and a load to which a DC voltage is supplied from the AC / DC converter. (Seventh configuration).

  According to the AC / DC converter according to the present invention and the electrical equipment including the same, the electrical connection on both the input and output sides of the first rectifying / smoothing circuit included in the plurality of rectifying / smoothing circuits connected in parallel is turned off. Therefore, it is possible to control the charging voltage of the output capacitor provided in each of the plurality of rectifying and smoothing circuits to be low. By performing the control, a current can be passed even in a situation where the input voltage is low, so that a high-efficiency conversion operation can be performed while suppressing a power factor decrease in a situation where the input voltage is low.

It is a figure which shows the structure of the alternating current direct current converter which concerns on 1st Embodiment of this invention. It is a figure which shows an example of a rectification smoothing circuit. It is a figure which shows the other example of a rectification smoothing circuit. It is a figure which shows the further another example of a rectification smoothing circuit. It is a figure which shows an example of a connection switching circuit. It is a figure which shows the other example of a connection switching circuit. It is a figure which shows the further another example of a connection switching circuit. It is a figure which shows the further another example of a connection switching circuit. It is a figure which shows the structure of the alternating current direct current converter which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of the alternating current direct current converter which concerns on 3rd Embodiment of this invention. It is a figure which shows the structure of the alternating current direct current converter which concerns on 4th Embodiment of this invention. It is a figure which shows the condition where the same load was separately attached to the 1st rectification smoothing circuit with which the alternating current direct current converter which concerns on 4th Embodiment of this invention is equipped, and a 4th rectification smoothing circuit. It is a figure which shows the current voltage waveform of each part in the condition shown in FIG. It is a figure which shows an example of the connection switching circuit used with the alternating current direct current converter which concerns on 5th Embodiment of this invention. It is a figure which shows the refrigerating cycle of an air conditioner.

  Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment>
FIG. 1 is a diagram showing a configuration of an AC / DC converter according to a first embodiment of the present invention. The AC / DC converter according to the present embodiment includes a first rectifying / smoothing circuit 1, a second rectifying / smoothing circuit 2, a third rectifying / smoothing circuit 3, and a connection switching circuit 4.

  One input terminal of each of the first to third rectifying and smoothing circuits 1 to 3 is connected to one end of the AC power supply P1, and the other input terminal of each of the first to third rectifying and smoothing circuits 1 to 3 is an AC power supply P1. Is connected to the other end. Each of the first to third rectifying / smoothing circuits 1 to 3 is a rectifying / smoothing circuit capable of turning on / off electrical connection with a circuit (AC power supply P1 in FIG. 1) connected to the input side. The rectification methods of the first to third rectifying / smoothing circuits 1 to 3 are not particularly limited. The output capacitor provided in the first rectifying / smoothing circuit 1 may be singular or plural. The number of output capacitors provided in the second rectifying / smoothing circuit 2 and the number of output capacitors provided in the third rectifying / smoothing circuit 3 may be either singular or plural.

  The connection switching circuit 4 includes a circuit connected to the output side (inverter circuit 5 in FIG. 1) and a plurality of rectifying / smoothing circuits (first to third rectifying / smoothing circuits 1 to 3 in this embodiment). The electrical connection can be turned on / off.

  In the AC / DC converter according to the present embodiment, electrical connection between the first rectifying and smoothing circuit 1 and the AC power source P1, electrical connection between the second rectifying and smoothing circuit 1 and the AC power source P1, and third rectifying and smoothing. An electrical connection between the circuit 3 and the AC power supply P1, an electrical connection between the first rectifying and smoothing circuit 1 and the inverter circuit 5, an electrical connection between the second rectifying and smoothing circuit 2 and the inverter circuit 5, and a third The electrical connection between the rectifying / smoothing circuit 1 and the inverter circuit 5 can be turned on / off independently.

  The inverter circuit 5 is a three-phase output inverter circuit that converts the output voltage of the AC / DC converter according to the present embodiment (= the output voltage of the connection switching circuit 4) into a three-phase motor drive voltage. To drive the three-phase motor 6.

  The controller 7 controls the first to third rectifying / smoothing circuits 1 to 3, the connection switching circuit 4, and the inverter circuit 5, and may be configured by, for example, a microcomputer.

  As a control example of the control unit 7, in the AC / DC converter according to the present embodiment, a phase detection unit that detects the phase of the AC voltage output from the AC power supply P1, and an output voltage of the first rectifying and smoothing circuit 1 are detected. A first voltage detector for detecting the output voltage of the second rectifying / smoothing circuit 2 and a third voltage detecting unit for detecting the output voltage of the third rectifying / smoothing circuit 3 are provided. A mode in which the control unit 7 controls the first to third rectifying / smoothing circuits 1 to 3 and the connection switching circuit 4 based on the detection results of the phase detection unit and the first to third voltage detection units is conceivable.

  For example, the control unit 7 sets the half cycle of the AC voltage output from the AC power supply P1 to a zone where the phase difference (absolute value) from the nearest zero cross point is less than the first predetermined value, and the phase difference from the nearest zero cross point. A section in which (absolute value) is greater than or equal to the first predetermined value and less than the second predetermined value (> first predetermined value), and a section in which the phase difference (absolute value) from the nearest zero cross point is greater than or equal to the second predetermined value Classify into three types. In this case, the control unit 7 connects the rectifying / smoothing circuit having the lowest charging voltage of one output capacitor and the AC power supply P1 in a section where the phase difference (absolute value) from the nearest zero cross point is less than the first predetermined value. Connect electrically. In addition, the control unit 7 charges one output capacitor in a section where the phase difference (absolute value) from the nearest zero-cross point is greater than or equal to the first predetermined value and less than the second predetermined value (> first predetermined value). The rectifying / smoothing circuit having the second lowest voltage is electrically connected to the AC power supply P1. Further, the control unit 7 electrically connects the rectifying / smoothing circuit having the highest charging voltage of one output capacitor and the AC power supply P1 in a section in which the phase difference (absolute value) from the nearest zero cross point is equal to or greater than the second predetermined value. Connect.

  And the control part 7 electrically connects a rectification smoothing circuit and the inverter circuit 5 so that load loss may decrease, for example. Note that the control unit 7 may exclude the rectifying / smoothing circuit electrically connected to the AC power supply P <b> 1 from the candidates for the rectifying / smoothing circuit electrically connected to the inverter circuit 5.

  According to the AC / DC converter according to the present embodiment, since the electrical connection on both the input and output sides of the first to third rectifying and smoothing circuits 1 to 3 can be turned off, the first to third rectifying and smoothing circuits. It is possible to control the charging voltage of the output capacitor provided in each of 1 to 3 to be low. By performing the control, a current can be passed even in a situation where the input voltage is low, so that a high-efficiency conversion operation can be performed while suppressing a power factor decrease in a situation where the input voltage is low. Further, by performing the control, the capacitance of the output capacitors provided in the first to third rectifying / smoothing circuits 1 to 3 is extremely reduced, and the outputs provided to the first to third rectifying / smoothing circuits 1 to 3 are performed. The usage rate of the capacitor can be improved. Further, by performing the control, it is possible to eliminate the reactor for changing the output voltage and reduce the capacity.

  Further, according to the AC / DC converter according to the present embodiment, the rectifying / smoothing circuit electrically connected to the AC power supply P1 is excluded from the candidates for the rectifying / smoothing circuit electrically connected to the inverter circuit 5, Even when the capacitance of the output capacitors provided in the first to third rectifying and smoothing circuits 1 to 3 is reduced, an output voltage that is not affected by the frequency of the AC power supply P1 can be obtained.

  Further, when the full-wave rectification method is used for the first rectifying and smoothing circuit 1 and the voltage doubler rectifying method is used for the second rectifying and smoothing circuit 2, even when the input voltage of the AC / DC converter according to the present embodiment is low. The output voltage of the AC / DC converter according to the present embodiment can be increased by using the output voltage of the second rectifying / smoothing circuit 2. For example, in the inverter circuit 5, the DC voltage is converted into a sinusoidal voltage by PWM (Pulse Width Modulation) control. However, the use of the output voltage of the first rectifying / smoothing circuit 1 and the second rectifying / smoothing circuit 2 Use of the output voltage and use of the difference between the output voltage of the first rectifying / smoothing circuit 1 and the output voltage of the second rectifying / smoothing circuit 2 (both ends of the plus side output of each output circuit are used as outputs) By switching between both ends of the minus side output, the inverter circuit 5 can generate a sinusoidal voltage even if the switching frequency in the inverter circuit 5 is reduced.

Next, FIG. 2A shows an example of a rectifying / smoothing circuit that can turn on / off electrical connection with a circuit connected to the input side. The rectifying / smoothing circuit shown in FIG. 2A uses a full-wave rectifying system, and includes a bridge circuit including input terminals T _IN1 and T _IN2 , thyristors TH1 and TH2, and diodes D1 and D2, an output capacitor C1, and an output terminal T. _OUT1 and _TOUT2 and control terminals _TCNT1 and _TCNT2 are provided.

The input terminal T _IN1 is connected to the anode of the thyristor TH1 and the cathode of the thyristor TH2, and the input terminal T _IN2 is connected to the anode of the diode D1 and the cathode of the diode D2. The output terminal T _OUT1 is connected to each cathode of the thyristor TH1 and the diode D1 and one end of the output capacitor C1, and the output terminal T _OUT2 is connected to each anode of the thyristor TH2 and the diode D2 and the other end of the output capacitor C1. .

Control terminal input signal (control voltage) to the T _CNT1 in can be switched on / off thyristors TH1, be switched on / off thyristor TH2 at the input signal to the control terminal T _CNT2 (control voltage) it can. By turning off the thyristors TH1 and TH2, the electrical connection between the rectifying / smoothing circuit shown in FIG. 2A and the circuit connected to the input side of the rectifying / smoothing circuit shown in FIG. 2A can be turned off. On the other hand, by turning on the thyristors TH1 and TH2, the electrical connection between the rectifying / smoothing circuit shown in FIG. 2A and the circuit connected to the input side of the rectifying / smoothing circuit shown in FIG. 2A can be turned on.

FIG. 2B shows another example of the rectifying / smoothing circuit that can turn on / off the electrical connection with the circuit connected to the input side. The rectifying / smoothing circuit shown in FIG. 2B uses a half-wave rectification method, and includes input terminals T _IN3 and T _IN4 , thyristor TH3, output capacitor C2, output terminals T _OUT3 and T _OUT4 , and control terminal T _CNT3 . It has.

The input terminal T _IN3 is connected to the anode of the thyristor TH3, and the cathode of the thyristor TH3 is connected to one end of the output capacitor C2 and the output terminal T _OUT3 . The input terminal T _IN4 is connected to the other end of the output capacitor C2 and the output terminal T _OUT4 .

The thyristor TH3 can be switched on / off by an input signal (control voltage) to the control terminal _TCNT3 . By turning off the thyristor TH3, the electrical connection between the rectifying / smoothing circuit shown in FIG. 2B and the circuit connected to the input side of the rectifying / smoothing circuit shown in FIG. 2B can be turned off. On the other hand, by turning on the thyristor TH3, the electrical connection between the rectifying / smoothing circuit shown in FIG. 2B and the circuit connected to the input side of the rectifying / smoothing circuit shown in FIG. 2B can be turned on.

FIG. 2C shows still another example of the rectifying / smoothing circuit that can turn on / off the electrical connection with the circuit connected to the input side. The rectifying / smoothing circuit shown in FIG. 2C uses a voltage doubler rectification method, and _controls input terminals T _IN5 and T _IN6 , thyristors TH4 and TH5, output capacitors C3 and C4, output terminals T _OUT5 and T _OUT6 , and control. Terminals _TCNT4 and _TCNT5 are provided.

The input terminal T _IN5 is connected to the anode of the thyristor TH4 and the cathode of the thyristor TH5, and the input terminal T _IN6 is connected to one end of each of the output capacitors C3 and C4. The output terminal T _OUT5 is connected to the cathode of the thyristor TH4 and the other end of the output capacitor C3, and the output terminal T _OUT6 is connected to the anode of the thyristor TH5 and the other end of the output capacitor C4.

Control terminal input signal (control voltage) to the T _CNT4 in can be switched on / off thyristor TH4, be switched on / off thyristors TH5 in the input signal to the control terminal T _CNT5 (control voltage) it can. By turning off the thyristors TH4 and TH5, the electrical connection between the rectifying / smoothing circuit shown in FIG. 2C and the circuit connected to the input side of the rectifying / smoothing circuit shown in FIG. 2C can be turned off. On the other hand, by turning on the thyristors TH4 and TH5, the electrical connection between the rectifying / smoothing circuit shown in FIG. 2C and the circuit connected to the input side of the rectifying / smoothing circuit shown in FIG. 2C can be turned on.

  In the rectifying and smoothing circuit shown in FIGS. 2A to 2C described above, a thyristor is used as a semiconductor switch. However, a semiconductor switch other than the thyristor (for example, a triac, a transistor, or the like) may be used. However, when a bidirectional semiconductor switch such as a triac or a transistor is used as a rectifier, control is performed so that the bidirectional semiconductor switch is always in an OFF state in a half cycle corresponding to the reverse direction.

  Next, when all of the first to third rectifying / smoothing circuits 1 to 3 are full-wave rectifier circuits or half-wave rectifier circuits having the same polarity, the negative electrode line (ground line) can be used in common. As the configuration of the connection switching circuit 4, for example, the configuration shown in FIG. 3A or the configuration shown in FIG. 3B can be adopted. The configuration shown in FIG. 3A uses a semiconductor switch, and the configuration shown in FIG. 3B uses a relay switch.

  On the other hand, when at least one of the first to third rectifying / smoothing circuits 1 to 3 is a voltage doubler rectifying circuit, the negative electrode line (ground line) cannot be used in common. The configuration shown in FIG. 3C or the configuration shown in FIG. 3D may be adopted. In the configuration shown in FIG. 3C, a relay switch is used, and in the configuration shown in FIG. 3D, a semiconductor switch is used.

  In the connection switching circuit shown in FIGS. 3A and 3D described above, a transistor is used as a semiconductor switch. However, a semiconductor switch other than a transistor (for example, a thyristor or a triac) may be used.

3A to 3D, V1 ₊ indicates a voltage output from the positive output terminal of the first rectifying and smoothing circuit 1, and V1 ₋ is output from the negative output terminal of the first rectifying and smoothing circuit 1. V2 ₊ represents a voltage output from the positive output terminal of the second rectifying and smoothing circuit 2, and V2 ₋ represents a voltage output from the negative output terminal of the second rectifying and smoothing circuit 2. the shows, V3 ₊ denotes a voltage output from the positive output terminal of the third rectifying and smoothing circuit 3, V3 _- indicates a voltage output from the negative output terminal of the third rectifying and smoothing circuit 3 ing.

Second Embodiment
FIG. 4 is a diagram showing a configuration of an AC / DC converter according to the second embodiment of the present invention. In FIG. 4, the same parts as those in FIG. The AC / DC converter according to the present embodiment includes a simple PAM (Pulse Amplitude Modulation) circuit 8, a first rectifying / smoothing circuit 1, a second rectifying / smoothing circuit 2, and a connection switching circuit 4.

  As shown in FIG. 4, the simple PAM circuit 8 includes a reactor, a diode bridge circuit, and a transistor. By using the reactor and the transistor, the current conduction angle is increased, and the output voltage is boosted. It is a circuit to do. One end of the reactor is connected to one end of the AC power supply P1 and one input terminal of the second rectifying / smoothing circuit 2, and the other end of the reactor is one input terminal of the first rectifying / smoothing circuit 1 and the diode bridge circuit. Is connected to one input terminal. The other input end of the first rectifying / smoothing circuit 1, the other input end of the second rectifying / smoothing circuit 2, and the other input end of the diode bridge circuit are connected to the other end of the AC power supply P1. Both output terminals of the diode bridge circuit are connected via the transistor.

  The control operation of the control unit 7 is slightly different from that of the first embodiment. In the present embodiment, the control unit 7 determines, for example, a half cycle of the AC voltage output from the AC power supply P1, a section where the phase difference (absolute value) from the nearest zero cross point is less than the third predetermined value, and the nearest zero cross point. And the phase difference (absolute value) is classified into two types of sections having a third predetermined value or more. In this case, the control unit 7 determines that the phase difference (absolute value) from the nearest zero cross point is less than the third predetermined value, the rectifying / smoothing circuit having the lower charging voltage of one output capacitor, and the AC power supply P1. Are electrically connected. Further, the control unit 7 connects the rectifying / smoothing circuit having the higher charging voltage of one output capacitor and the AC power supply P1 in a section where the phase difference (absolute value) from the nearest zero cross point is equal to or greater than the third predetermined value. Connect electrically.

  And the control part 7 electrically connects a rectification smoothing circuit and the inverter circuit 5 so that load loss may decrease, for example. Note that the control unit 7 may exclude the rectifying / smoothing circuit electrically connected to the AC power supply P <b> 1 from the candidates for the rectifying / smoothing circuit electrically connected to the inverter circuit 5.

  Further, the control unit 7 controls the on-duty of the transistors in the simple PAM circuit 8.

  According to the AC / DC converter according to the present embodiment, since the simple PAM circuit 8 is mounted, the power factor can be further improved as compared with the first embodiment.

<Third Embodiment>
FIG. 5 is a diagram showing a configuration of an AC / DC converter according to the third embodiment of the present invention. 5, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. The AC / DC converter according to the present embodiment includes a first rectifying / smoothing circuit 1, a second rectifying / smoothing circuit 2, and a connection switching circuit 4. In the present embodiment, the first rectifying / smoothing circuit 1 and the second rectifying / smoothing circuit 2 each use a full-wave rectifying method, and a bridge circuit, an output capacitor, and an active filter method provided between them. And a power factor correction circuit 9.

  The control operation of the control unit 7 is almost the same as in the second embodiment. In this embodiment, the control unit 7 does not control the on-duty of the transistor in the simple PAM circuit 8 but controls the on / off of the transistor in the active filter type power factor correction circuit 9.

  According to the AC / DC converter according to the present embodiment, since the active filter type power factor improvement circuit 9 is mounted, the power factor can be further improved as compared with the first embodiment.

<Fourth embodiment>
FIG. 6 is a diagram showing a configuration of an AC / DC converter according to the fourth embodiment of the present invention. In FIG. 6, the same parts as those in FIG. The AC / DC converter according to the present embodiment includes a first rectifying / smoothing circuit 1, a fourth rectifying / smoothing circuit 10, and a switch SW1. The fourth rectifying / smoothing circuit 10 is a rectifying / smoothing circuit that cannot turn on / off electrical connection with a circuit connected to the input side. Example of “third rectifying and smoothing circuit in which electrical connection with AC power source connected to the side is always on and electrical connection with a load connected to the output side of the AC to DC converter is always on” It is.

  In the AC / DC converter according to the present embodiment, the output of the first rectifying / smoothing circuit 1 and the output of the fourth rectifying / smoothing circuit 10 are combined and supplied to the inverter circuit 5 when the switch SW1 is on. Only the output of the fourth rectifying / smoothing circuit 10 is supplied to the inverter circuit 5 when the switch SW1 is in the OFF state.

  The control unit 7 performs control to keep the charging voltage of the output capacitor provided in the first rectifying and smoothing circuit 1 low. That is, the control unit 7 determines that the half cycle of the AC voltage output from the AC power supply P1 is a zone T1 to T4 in which the phase difference (absolute value) from the nearest zero cross point is less than the first predetermined value, and the nearest zero cross point. The phase difference (absolute value) is classified into two types of sections where the phase difference (absolute value) is greater than or equal to the first predetermined value, and in the sections T1 to T4 where the phase difference (absolute value) from the nearest zero cross point is less than the first predetermined value, The first rectifying / smoothing circuit 1 and the AC power source P1 are electrically connected, and the first rectifying / smoothing circuit 1 and the first rectifying / smoothing circuit 1 The AC power supply P1 is not electrically connected. In each of the sections T1 to T4 in which the phase difference (absolute value) from the nearest zero cross point is less than the first predetermined value, a sub section that electrically connects the first rectifying and smoothing circuit 1 and the AC power supply P1. A section in which the first rectifying / smoothing circuit 1 and the sub-section in which the AC power supply P1 is not electrically connected is periodically repeated, and the phase difference (absolute value) from the nearest zero-cross point is equal to or greater than the first predetermined value. In this case, the first rectifying / smoothing circuit 1 and the AC power supply P1 may not be electrically connected.

  Here, for convenience of explanation, a situation where the same load (inverter circuit 5 and three-phase motor 6) is separately attached to the first rectifying / smoothing circuit 1 and the fourth rectifying / smoothing circuit 10, that is, the situation shown in FIG. The explanation will be given.

  FIG. 8 is a diagram showing current voltage waveforms at various parts in the situation shown in FIG. Waveform W1 is the output voltage waveform of AC power supply P1, waveform W2 is the voltage waveform of the output capacitor of first rectifying and smoothing circuit 1, and waveform W3 is the voltage waveform of the output capacitor of fourth rectifying and smoothing circuit 10. , Waveform W4 is an input current waveform of the first rectifying / smoothing circuit 1, and waveform W5 is an input current waveform of the fourth rectifying / smoothing circuit 10.

  Since only the fourth rectifying / smoothing circuit 10 is not provided with the power factor correction circuit, the period during which the current flows is very short. However, since the first rectifying / smoothing circuit 1 is provided in the present embodiment, The flowing period can be expanded.

<Fifth Embodiment>
The AC / DC converter according to the fifth embodiment of the present invention relates to at least one of the semiconductor switches in the first to third rectifying and smoothing circuits 1 to 3, the switches in the connection switching circuit 4, and the switch SW1. It differs from the AC / DC converter according to the other embodiment in that a plurality of semiconductor switches that are connected in parallel and have different loss characteristics are used instead of the single switch, and other points are different from the other embodiments. What is necessary is just to make it the same as either of the AC / DC converters which concern. Examples of the semiconductor switch used in this embodiment include an IGBT (Insulated Gate Bipolar Transistor), a GaN-based transistor, and an SiC-based transistor.

  In the AC / DC converter according to the present embodiment, for example, the connection switching circuit shown in FIG. 9 is used instead of the connection switching circuit 4 shown in FIG. 3A. Then, in each line of the connection switching circuit shown in FIG. 9, a semiconductor switch having a better loss characteristic according to the value of the current flowing on the line is used. Therefore, a current detection unit that detects the value of the current flowing on the line may be provided, and the control unit 7 may control the connection switching circuit shown in FIG. 9 based on the detection result of the current detection unit.

<Sixth Embodiment>
The AC / DC converter according to each of the embodiments described above can be mounted on various electrical devices and can drive a load of the electrical device. In this embodiment, the AC / DC converter according to each embodiment described above is mounted on an air conditioner.

  Here, the refrigeration cycle of the air conditioner is shown in FIG.

  In the outdoor unit 100, a compressor 11, a four-way valve 12, an outdoor heat exchanger 13, an expansion valve 14, and an outdoor fan 15 are provided. In the indoor unit 200, an indoor heat exchanger 16 and an indoor fan 17 are provided. The three-phase motor 6 in each embodiment described above is used as a compressor motor provided in the compressor 11.

  The compressor 11 operates the refrigeration cycle by circulating the refrigerant in the refrigerant pipe 18.

  The outdoor heat exchanger 13 and the indoor heat exchanger 16 have a large number of fins close to the refrigerant pipe 18 and exchange heat with air passing between the fins.

  Each end of the outdoor heat exchanger 13 and the indoor heat exchanger 16 is connected to the compressor 11 via a four-way valve 12 and a refrigerant pipe 18. The other ends of the outdoor heat exchanger 13 and the indoor heat exchanger 16 are connected to each other via an expansion valve 14 and a refrigerant pipe 18.

  The outdoor fan 15 is disposed opposite to the outdoor heat exchanger 13. Outdoor air is supplied to the outdoor heat exchanger 13 by driving the outdoor fan 15, and heat exchange between the outdoor heat exchanger 13 and the outdoor air is promoted. The air that has exchanged heat with the outdoor heat exchanger 13 is exhausted to the outside through an exhaust port that faces the outdoor fan 15 and opens in front of the outdoor unit 100.

  The indoor heat exchanger 16 and the indoor fan 17 are arranged in a ventilation passage provided in the indoor unit 200. Indoor air flows into the ventilation passage by driving the indoor fan 17 and is supplied to the indoor heat exchanger 16, and heat exchange between the air flowing through the ventilation passage and the indoor heat exchanger 16 is performed. The air that has exchanged heat with the indoor heat exchanger 16 is sent into the room through a blowout opening that opens in the operating state below the indoor unit 200 and closes when the operation is stopped.

  During the heating operation, the outdoor fan 15 and the indoor fan 17 are driven, and the four-way valve 12 is switched as indicated by a solid line in the figure. Thus, the refrigerant flows in the direction indicated by the arrow A by driving the compressor 11, and the high-temperature and high-pressure refrigerant compressed by the compressor 11 is condensed while releasing heat in the indoor heat exchanger 16.

  The high-temperature refrigerant becomes low-temperature and low-pressure at the expansion valve 14 and is sent to the outdoor heat exchanger 13. The refrigerant flowing into the outdoor heat exchanger 13 evaporates while absorbing heat to become a low-temperature gas refrigerant, and is sent to the compressor 11. By this refrigeration cycle, the air that has exchanged heat with the indoor heat exchanger 16 that is the high temperature part of the refrigeration cycle is sent out indoors by the indoor fan 17 and the room is heated. In addition, the air exchanged with the outdoor heat exchanger 13 that is a low temperature part of the refrigeration cycle is exhausted to the outside by the outdoor fan 15.

  During the cooling operation, the outdoor fan 15 and the indoor fan 17 are driven, and the four-way valve 12 is switched as indicated by a broken line in the figure. As a result, the refrigerant flows in the direction opposite to the arrow A by driving the compressor 11, the indoor heat exchanger 16 becomes the low temperature part of the refrigeration cycle, and the outdoor heat exchanger 13 becomes the high temperature part of the refrigeration cycle. The air that has exchanged heat with the indoor heat exchanger 16 is sent out indoors by the indoor fan 17 to cool the room. Water generated by agglomeration of water vapor heat exchanged with the indoor heat exchanger 16 is discharged to the outside from the drain pipe. In addition, the air exchanged with the outdoor heat exchanger 13 that is a high temperature part of the refrigeration cycle is exhausted to the outside by the outdoor fan 15.

  In addition to the air conditioner composed of an indoor unit and an outdoor unit, the electric device includes an integrated air conditioner, a refrigerator, a washing machine, a vacuum cleaner, a fan, and a dehumidifier equipped with a heat pump.

<Others>
Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention. For example, the number of rectifying and smoothing circuits is not limited to each embodiment. Further, from the viewpoint of cost reduction and miniaturization of the AC / DC converter, it is disadvantageous compared to each embodiment, but rectification that can turn on / off electrical connection with a circuit connected to the input side. Instead of a smoothing circuit, a normal rectifying / smoothing circuit that cannot turn on / off electrical connection with a circuit connected to the input side is used, and a switch is provided in front of the input side of the normal rectifying / smoothing circuit. May be. In the second embodiment, the configuration using the simple PAM circuit 8 is described. In the third embodiment, the configuration using the active filter type power factor improvement circuit 9 is described. A power factor correction circuit other than the power factor correction circuit (such as a power factor correction circuit consisting only of a reactor or an interleaved power factor correction circuit using an active filter method in parallel) may be used.

  The AC-DC converter described above is an AC-DC converter including a plurality of rectifying / smoothing circuits (1, 2, 3), wherein the plurality of rectifying / smoothing circuits (1, 2, 3) are connected in parallel. First switching means (TH1 to TH5) that can turn on / off electrical connection between the AC power source (P1) connected to the input side of the AC / DC converter and at least the first rectifying / smoothing circuit (1). ), And a second (5, 6) connected to the output side of the AC / DC converter and at least a first rectifying / smoothing circuit (1) can be turned on / off. Switching means (4), and the first rectifying / smoothing circuit (1) is included in the plurality of rectifying / smoothing circuits (1, 2, 3) (first structure).

  According to such a configuration, it is possible to turn off the electrical connection on both the input and output sides of the first rectifying / smoothing circuit included in the plurality of rectifying / smoothing circuits connected in parallel. It is possible to control the charging voltage of the output capacitor provided to be low. By performing the control, a current can be passed even in a situation where the input voltage is low, so that a high-efficiency conversion operation can be performed while suppressing a power factor decrease in a situation where the input voltage is low.

  In the AC / DC converter of the first configuration, the first switching means (TH1, TH2, TH4, TH5) includes an AC power source (P1) connected to an input side of the AC / DC converter, and the first The electrical connection with each of the first rectifying / smoothing circuit (1) and the second rectifying / smoothing circuit (2) can be turned on / off, and the second switching means (4) is connected to the AC / DC converter. The electrical connection between the load (5, 6) connected to the output side and each of the first rectifying / smoothing circuit (1) and the second rectifying / smoothing circuit (2) can be turned on / off, The second rectifying / smoothing circuit (2) is included in the plurality of rectifying / smoothing circuits, the first rectifying / smoothing circuit (1) uses a full-wave rectifying method, and the second rectifying / smoothing circuit (2) prefers the configuration using the voltage doubler rectification method (second configuration). .

  According to such a configuration, the output voltage of the AC / DC converter can be increased by using the output voltage of the second rectifying / smoothing circuit 2 even when the input voltage of the AC / DC converter is low.

  In the AC / DC converter of the first or second configuration, the first switching means includes a semiconductor switch provided in the first rectifying / smoothing circuit (1) and the second rectifying / smoothing circuit (2). A configuration (third configuration) including a semiconductor switch provided therein is preferable.

  According to such a configuration, it is not necessary to provide a switch outside the rectifying / smoothing circuit as the first switching means, so that the cost and size of the AC / DC converter can be reduced.

  In the AC to DC converter having any one of the first to third configurations, a configuration (fourth configuration) including a power factor correction circuit (8, 9) is preferable.

  According to such a configuration, the power factor can be further improved.

  In the AC to DC converter of any of the first to fourth configurations, electrical connection with an AC power source connected to the input side of the AC to DC converter is always on, and the output of the AC to DC converter A configuration (fifth configuration) in which a third rectifying and smoothing circuit in which electrical connection with a load connected to the side is always on is included in the plurality of rectifying and smoothing circuits may be employed.

  According to such a configuration, the period during which current flows through the third rectifying / smoothing circuit itself is very short, but since the first rectifying / smoothing circuit is provided, the period during which current flows can be expanded.

  In the AC / DC converter of any one of the first to fifth configurations, the first switching means includes a plurality of semiconductor switches that are connected in parallel and have different loss characteristics, and / or A configuration (sixth configuration) in which the two switching units are connected in parallel and each have a plurality of semiconductor switches having different loss characteristics is preferable.

  According to such a configuration, the loss in the semiconductor switch of the first switching means and / or the second switching means can be reduced by using the semiconductor switch having good loss characteristics according to the current value. The conversion efficiency of the AC / DC converter can be improved.

  The electrical device described above is a configuration (seventh configuration) including the AC to DC converter having any one of the first to sixth configurations and a load to which a DC voltage is supplied from the AC to DC converter. .

1 to 3 First to third rectifying and smoothing circuits 4 Connection switching circuit 5 Inverter circuit 6 Three-phase motor 8 Simple PAM circuit 9 Active filter type power factor correction circuit 10 Fourth rectifying and smoothing circuit C1 to C4 Output capacitor D1, D2 Diode SW1 Switch TH1 to TH5 Thyristor

Claims (6)

It has a plurality of rectifying and smoothing circuits,
An AC / DC converter in which the plurality of rectifying and smoothing circuits are connected in parallel,
A first switching means capable of turning on / off the electrical connection between the AC power source connected to the input side of the AC / DC converter and at least the first rectifying / smoothing circuit;
A second switching means capable of turning on / off the electrical connection between the load connected to the output side of the AC / DC converter and at least the first rectifying / smoothing circuit;
The first rectifying / smoothing circuit and the second rectifying / smoothing circuit are included in the plurality of rectifying / smoothing circuits ,
The first switching unit turns on / off electrical connection between an AC power source connected to the input side of the AC / DC converter and each of the first rectifying / smoothing circuit and the second rectifying / smoothing circuit. It is possible,
The second switching unit turns on / off electrical connection between a load connected to the output side of the AC / DC converter and each of the first rectifying / smoothing circuit and the second rectifying / smoothing circuit. Can
2. The AC / DC converter according to claim 1, wherein the first rectifying / smoothing circuit uses a full-wave rectifying method, and the second rectifying / smoothing circuit uses a voltage doubler rectifying method . It has a plurality of rectifying and smoothing circuits,
An AC / DC converter in which the plurality of rectifying and smoothing circuits are connected in parallel,
A first switching means capable of turning on / off the electrical connection between the AC power source connected to the input side of the AC / DC converter and at least the first rectifying / smoothing circuit;
A second switching means capable of turning on / off the electrical connection between the load connected to the output side of the AC / DC converter and at least the first rectifying / smoothing circuit;
The first rectifying / smoothing circuit is included in the plurality of rectifying / smoothing circuits;
The first switching means includes a plurality of semiconductor switches that are connected in parallel and have different loss characteristics, and / or a plurality of semiconductor switches that are connected in parallel and have different loss characteristics. An AC / DC converter having a semiconductor switch . The AC / DC converter according to claim 1 , wherein the first switching unit includes a semiconductor switch provided in the first rectifying / smoothing circuit and a semiconductor switch provided in the second rectifying / smoothing circuit.   The AC / DC converter according to any one of claims 1 to 3, further comprising a power factor correction circuit.   The electrical connection with the AC power source connected to the input side of the AC / DC converter is always on, and the electrical connection with the load connected to the output side of the AC / DC converter is always on. The AC / DC converter according to claim 1, wherein the rectifying / smoothing circuit is included in the plurality of rectifying / smoothing circuits. The AC to DC converter according to any one of claims 1 to 5,
An electric device comprising: a load to which a DC voltage is supplied from the AC / DC converter.

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