JP2022156565A - Power conversion device - Google Patents

Abstract

To reduce the circuit size of a power conversion device in which a rectifier circuit is operated in two types of rectification modes.SOLUTION: A power conversion device (1) includes a positive voltage side power supply line (21) and a negative voltage side power supply line (22), a rectifier circuit (10) that converts input AC supplied to first and second input terminals (TE1, TE2) from a single-phase AC power supply (2) into DC and outputs to the positive voltage side power supply line (21) and the negative voltage side power supply line (22), and first and second capacitors (31, 32) connected in series with each other between the positive voltage side power supply line (21) and the negative voltage side power supply line (22). The power conversion device (1) further includes a reverse-conducting switch (50), one end of which is connected to the connection point (CP) of the first and second capacitors (31, 32) while the other end is connected to the first inputting terminal (TE1).SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a power conversion device including a rectifier circuit that converts input AC supplied from a single-phase AC power supply to DC.

The power conversion device disclosed in Patent Document 1 converts the input AC supplied to the first and second input terminals from the single-phase AC power supply to DC and outputs it to the positive voltage side power line and the negative voltage side power line. a rectifier circuit, first and second capacitors connected in series between the positive voltage side power supply line and the negative voltage side power supply line, and one end connected to a connection point of the first and second capacitors. and a bidirectional switch whose other end is connected to the first input terminal. A bidirectional switch has a bridge circuit having four diodes and a unidirectional switch element using a transistor. In this power converter, the rectifier circuit can be operated in two rectification modes by switching on and off the unidirectional switch element of the bidirectional switch.

Japanese Patent No. 3516601

However, in Patent Document 1, a bidirectional switch having four diodes is used for switching the rectification mode, so the number of elements increases and the circuit size increases.

An object of the present disclosure is to reduce the circuit scale of a power converter that operates a rectifier circuit in two rectification modes.

In a first aspect of the present disclosure, a power conversion device (1) includes a positive voltage side power line (21), a negative voltage side power line (22), and a single-phase AC power supply (2) from first and second a rectifier circuit (10) for converting an input alternating current supplied to the input terminals (TE1, TE2) into a direct current and outputting it to the positive voltage side power line (21) and the negative voltage side power line (22); first and second capacitors (31, 32) connected in series between the side power line (21) and the negative voltage side power line (22); , 32), and a reverse conducting switch (50) having the other end connected to the first input terminal (TE1).

In the first aspect, in switching the rectification mode, whether or not to allow current to flow in one direction is controlled, and in the other direction, the reverse conduction switch ( 50) (for example, a reverse conducting switch (50) composed of one diode and one bipolar or unipolar transistor) is used, so it has four diodes and one unidirectional switch as in Patent Document 1 Compared to the case of using a bidirectional switch, the number of elements can be reduced and the circuit scale can be reduced.

In a second aspect of the present disclosure, in the first aspect, current flows in a direction from the first input terminal (TE1) to the connection point (CP) when the reverse conducting switch (50) is in an OFF state. , the capacitor (31) on the positive voltage side power supply line (21) side of the first and second capacitors (31, 32) is a non-polar capacitor, and the reverse conducting switch (50) is connected so that current flows in the direction from the connection point (CP) to the first input terminal (TE1) in the OFF state, the first and second capacitors (31, 32), the capacitor (32) on the side of the negative voltage power supply line (22) is a non-polar capacitor.

In the second aspect, when the reverse conduction switch (50) is connected so that current flows in the direction from the first input terminal (TE1) to the connection point (CP) in the OFF state, the positive Since the capacitor (31) on the voltage side power line (21) side is a non-polar capacitor, when the reverse conduction switch (50) is turned off to the positive voltage side power line (21) side capacitor (31) can be applied with a negative voltage.

On the other hand, when the reverse conduction switch (50) is connected so that the current flows in the direction from the connection point (CP) to the first input terminal (TE1) in the OFF state, the negative voltage side power supply line Since the capacitor (32) on the (22) side is a non-polar capacitor, a negative voltage is applied to the capacitor (32) on the negative voltage side power supply line (22) when the reverse conduction switch (50) is turned off. can be printed.

In a third aspect of the present disclosure, in the first aspect, current flows in a direction from the first input terminal (TE1) to the connection point (CP) when the reverse conducting switch (50) is in an OFF state. , the capacitor (31) on the positive voltage side power supply line (21) side of the first and second capacitors (31, 32) is a polar capacitor, and the positive voltage side A diode (34) is connected in parallel with the capacitor (31) on the power line (21) side with its cathode facing the positive electrode side of the capacitor (31), and the reverse conduction switch (50) is turned off. state, the current flows in the direction from the connection point (CP) to the first input terminal (TE1), the first and second capacitors (31, 32) The capacitor (32) on the negative voltage side power supply line (22) side is a polar capacitor, and the diode (33) connects the cathode of the capacitor (32) on the negative voltage side power supply line (22) side to the capacitor ( 32) is connected in parallel with the positive electrode side thereof facing.

In the third aspect, when the reverse conducting switch (50) is connected so that the current flows in the direction from the first input terminal (TE1) to the connection point (CP) in the OFF state, the positive voltage side Since a polar capacitor is used as the capacitor (31) on the power line (21) side, the size of the capacitor (31) on the positive voltage power line (21) can be reduced compared to the case of using a non-polar capacitor. In addition, since the absolute value of the reverse voltage applied to the capacitor (31) on the positive voltage side power line (21) can be made equal to or less than the forward voltage of the diode (34), the positive voltage side power line (21) It is possible to suppress failure of the capacitor (31) on the side due to application of a reverse voltage having a large absolute value to the capacitor (31).

When the reverse conduction switch (50) is connected so that the current flows in the direction from the connection point (CP) to the first input terminal (TE1) in the OFF state, the negative voltage side power supply line (22) side Since a polar capacitor is used as the capacitor (32), the size of the capacitor (32) on the side of the negative voltage side power supply line (22) can be reduced compared to the case of using a non-polar capacitor. In addition, since the absolute value of the reverse voltage applied to the capacitor (32) on the negative voltage side power line (22) can be made equal to or less than the forward voltage of the diode (33), the negative voltage side power line (22) It is possible to suppress the failure of the capacitor (32) due to the reverse voltage having a large absolute value being applied to the capacitor (32) on the side.

In the fourth aspect of the present disclosure, in any one of the first to third aspects, the reverse conducting switch (50 ) and a second drive mode in which the reverse conducting switch (50) is always turned off in the one half period of each period of the input alternating current. wherein the reverse conduction switch (50) is turned off so that the current flows in the current direction from the connection point (CP) to the first input terminal (TE1). , the one half cycle is a half cycle (HC1) in which the voltage of the first input terminal (TE1) is equal to or greater than the voltage of the second input terminal (TE2), When the reverse conducting switch (50) is connected so that the current flows in the current direction from the first input terminal (TE1) to the connection point (CP) in the OFF state, the one half cycle is a half cycle (HC2) in which the voltage of the second input terminal (TE2) is equal to or higher than the voltage of the first input terminal (TE1).

In the fourth aspect, in the first and second drive modes, the output voltage of the rectifier circuit (10), that is, the voltage of the positive voltage side power line (21) with respect to the negative voltage side power line (22) is different from each other. You can transition with

According to a fifth aspect of the present disclosure, in the fourth aspect, the direct current input to the positive voltage side power line (21) and the negative voltage side power line (22) is converted into direct current or alternating current and supplied to the load. A power conversion circuit (40) is further provided, and the controller controls the power conversion circuit (40), the single-phase AC power supply (2), and the load (3) based on the state of at least one of the Either one of the first and second driving modes is selected, and the reverse conducting switch (50) is controlled in the selected driving mode.

In a fifth aspect, the mode of transition of the output voltage of the rectifier circuit (10) is based on the state of at least one of the power conversion circuit (40), the single-phase AC power supply (2), and the load (3). , are selected from two aspects corresponding to the first and second drive modes.

A sixth aspect of the present disclosure is characterized in that, in the fourth or fifth aspect, at least one of the length of the ON period (T1) and the start timing is variable.

In the sixth aspect, the aspect of transition of the output voltage of the rectifier circuit (10) in the first drive mode can be changed.

According to a seventh aspect of the present disclosure, in any one of the fourth to sixth aspects, the reverse conducting switch (50) is composed of a unipolar transistor, and the control section (60) controls each of the input alternating currents. On-control for turning on the reverse conducting switch (50) is performed in the other half period of the cycle, and during the on-control, a current flows through the channel of the reverse conducting switch (50) in the current direction. and

In the seventh aspect, during ON control, the current flowing in the current direction can flow through the channel of the reverse conducting switch (50), so power loss in the reverse conducting switch (50) can be reduced compared to the case where the current flows only through the body diode. .

According to an eighth aspect of the present disclosure, in any one of the fourth to seventh aspects, the controller (60) controls the reverse conduction switch (50) when no current is flowing through the reverse conduction switch (50). (50) from an on state to an off state; ) from the OFF state to the ON state.

In the eighth aspect, the switching loss of the reverse conducting switch (50) can be reduced.

FIG. 1 is a circuit diagram showing the configuration of the power converter according to Embodiment 1 and the flow of current in the ON state of the reverse conduction switch. FIG. 2 is a view corresponding to FIG. 1 in the off state of the reverse conducting switch. FIG. 3(a) is a timing chart illustrating the power supply voltage in the first drive mode, and FIG. 3(b) is a diagram corresponding to FIG. (c) is a diagram corresponding to FIG. 3(a) of the DC voltage and the voltages of the first and second capacitors. 4A is a diagram corresponding to FIG. 3A in the second driving mode, FIG. 4B is a diagram corresponding to FIG. 3B in the second driving mode, and FIG. ) is a view corresponding to FIG. 3(c) in the second drive mode. FIG. 5 is a circuit diagram showing the configuration of the power converter according to the second embodiment. FIG. 6 is a view corresponding to FIG. 4(c) of the second embodiment. FIG. 7 is a circuit diagram showing the configuration of the power converter according to Embodiment 3 and the current flow in the half cycle in which the power supply voltage is negative in the second drive mode. FIG. 8 is a diagram corresponding to FIG. 7 in a half cycle in which the power supply voltage is positive in the second drive mode. 9A is a diagram corresponding to FIG. 4A of Embodiment 3, and FIG. 9B is a diagram corresponding to FIG. , FIG. 9(c) is a view corresponding to FIG. 4(c) of the third embodiment. FIG. 10 is a circuit diagram showing the configuration of a power converter according to Embodiment 4. FIG. FIG. 11 is a view corresponding to FIG. 9(c) of the fourth embodiment. FIG. 12 is a timing chart illustrating DC voltages in the fifth embodiment. FIG. 13(a) is a timing chart illustrating the DC voltage before and after the ON period and the voltages of the first and second capacitors, and FIG. 13(b) is the control signal of the reverse conducting switch. It is an equivalent diagram. FIG. 14 is a circuit diagram showing the configuration of the power converter according to the sixth embodiment. FIG. 15(a) is a diagram corresponding to FIG. 3(b) of Embodiment 7, and FIG. 15(b) is a diagram corresponding to FIG. 15(a) of the control signal of the reverse conduction switch.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The following embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its applications, or its uses.

(Embodiment 1)
FIG. 1 shows a power converter (1) according to Embodiment 1 of the present disclosure. This power converter (1) converts an input alternating current supplied from a single-phase alternating current power supply (2) into alternating current having a desired frequency and voltage, and supplies the alternating current to an electric motor (3) as a load.

A power converter (1) includes a reactor (L), a rectifier circuit (10), a positive voltage side power line (21), a negative voltage side power line (22), first and second capacitors (31, 32), an inverter circuit (40) as a power conversion circuit, a reverse conduction switch (50), and a control section (60).

The reactor (L) is connected between the single-phase AC power supply (2) and the first input terminal (TE1) of the rectifier circuit (10). Therefore, current from the single-phase AC power supply (2) is input to the first input terminal (TE1) of the rectifier circuit (10) via the reactor (L).

The rectifier circuit (10) converts the input alternating current supplied from the single-phase alternating current power supply (2) to the first and second input terminals (TE1, TE2) into direct current and supplies the positive voltage side power supply line (21) and the negative voltage side power supply line (21). Output to the voltage side power line (22). The rectifier circuit (10) has first to fourth rectifier circuit diodes (11 to 14) connected in a bridge configuration. These rectifier circuit diodes (11 to 14) have their cathodes directed toward the positive voltage power supply line (21) and their anodes directed toward the negative voltage power supply line (22). The first and second rectifier circuit diodes (11, 12) are arranged between the positive voltage power line (21) and the negative voltage power line (22) in order from the positive voltage power line (21). They are connected in series and their contacts are connected to the first input terminal (TE1). The third and fourth rectifier circuit diodes (13, 14) are connected between the positive voltage power line (21) and the negative voltage power line (22) in order from the positive voltage power line (21). They are connected in series and their contacts are connected to the second input terminal (TE2).

The first and second capacitors (31, 32) are connected in series between the positive voltage power line (21) and the negative voltage power line (22) in order from the positive voltage power line (21). ing. That is, the first capacitor (31) is connected to the positive voltage power line (21), and the second capacitor (32) is connected to the negative voltage power line (22). The first capacitor (31) is a polarized capacitor. On the other hand, the second capacitor (32) is a nonpolar capacitor.

The inverter circuit (40) converts the direct current input to the positive voltage power supply line (21) and the negative voltage power supply line (22) by the rectifier circuit (10) into alternating current through switching operation and supplies the alternating current to the electric motor (3). do. Specifically, the inverter circuit (40) has six switching elements (41a-46a) and six free wheel diodes (41b-46b). The six switching elements (41a-46a) are bridge-connected. More specifically, the inverter circuit (40) has three switching legs connected between the positive voltage power line (21) and the negative voltage power line (22). A switching leg consists of two switching elements (41a-46a) connected in series. In each of the three switching legs, the midpoint between the upper arm switching elements (41a, 43a, 45a) and the lower arm switching elements (42a, 44a, 46a) is the coil (u phase, v-phase, and w-phase coils). One freewheeling diode (41b-46b) is connected in anti-parallel to each switching element (41a-46a).

The reverse conduction switch (50) includes a bipolar transistor (51) and a reverse conduction switch diode (52) connected in antiparallel to the bipolar transistor (51).

The collector of the bipolar transistor (51) is connected to the first input terminal (TE1) and the emitter of the bipolar transistor (51) is connected to the connection point (CP) of the first and second capacitors (31,32). It is

The anode of the reverse conduction switch diode (52) is connected to the connection point (CP) of the first and second capacitors (31, 32) and the emitter of the bipolar transistor (51). The cathode of the reverse conduction switch diode (52) is connected to the first input terminal (TE1) and the collector of the bipolar transistor (51).

Thus, one end of the reverse conducting switch (50) is connected to the connection point (CP) of the first and second capacitors (31, 32), while the other end of the reverse conducting switch (50) is connected to the second 1 input terminal (TE1). The reverse conduction switch (50) is connected so that current flows in the direction from the connection point (CP) to the first input terminal (TE1) in the OFF state in which the bipolar transistor (51) is turned off.

The control section (60) controls the switching operation of each switching element (41a-46a) by outputting a switching signal to each switching element (41a-46a) of the inverter circuit (40).

In addition, the control section (60) can control the reverse conducting switch in the first drive mode and the second drive mode. The first drive mode is a predetermined half cycle (indicated by symbol HC1 in FIG. 3B) in which the voltage of the first input terminal (TE1) is equal to or higher than the voltage of the second input terminal (TE2). is a mode in which the reverse conduction switch (50) is turned on during the ON period (indicated by symbol T1 in FIG. 3B), and the second drive mode is a mode in which the voltage of the first input terminal (TE1) is the second In this mode, the reverse conduction switch (50) is always turned off in the half cycle (HC1) when the voltage at the input terminal (TE2) of the input terminal (TE2) is higher than the voltage of the input terminal (TE2). In Embodiment 1, the control section (60) always turns on the reverse conduction switch (50) in the first drive mode. Thus, the predetermined ON period (T1) is the entire half cycle (HC1) during which the voltage of the first input terminal (TE1) is greater than or equal to the voltage of the second input terminal (TE2). On the other hand, in the second driving mode, the reverse conducting switch (50) is always turned off. The control section (60) selects either one of the first and second drive modes based on an input from a user or an external device, and controls the reverse conducting switch (50) in the selected drive mode.

FIGS. 3(a) to 3(c) show voltage values and current values of each part in the first drive mode of the power converter (1) configured as described above. FIG. 3(a) shows the power supply voltage between the first input terminal (TE1) and the second input terminal (TE2). The power supply voltage when the first input terminal (TE1) has a higher potential than the second input terminal (TE2) is assumed to be positive. FIG. 3(b) shows the power supply current flowing from the single-phase AC power supply (2) into the first and second input terminals (TE1, TE2) and the reverse conducting switch current flowing through the reverse conducting switch (50). The reverse conduction switch current in the rectification direction of the reverse conduction switch diode (52), that is, the direction from the connection point (CP) to the first input terminal (TE1) is assumed to be negative. FIG. 3(c) shows the DC (direct current) voltage (direct current link voltage) between the positive voltage side power line (21) and the negative voltage side power line (22), the first and second capacitors (31 ,32).

In the power converter (1) configured as described above, in the first drive mode, the voltage of the first input terminal (TE1) is the half cycle (HC1 ) in the direction indicated by the arrow AR1 in FIG. 1, and the second capacitor (32) is charged. At this time, current flows from the first input terminal (TE1) to the second capacitor (32) through the bipolar transistor (51) of the reverse conduction switch (50). Further, a current flows from the second capacitor (32) to the second input terminal (TE2) through the fourth rectifier circuit diode (14).

Also, in the first drive mode, a part of the half cycle (indicated by symbol HC2 in FIG. 3B) in which the voltage of the second input terminal (TE2) is equal to or higher than the voltage of the first input terminal (TE1) , current flows in the direction indicated by the arrow AR2 in FIG. 1, and the first capacitor (31) is charged. At this time, a current flows from the second input terminal (TE2) to the first capacitor (31) through the third rectifier circuit diode (13). Further, a current flows from the first capacitor (31) to the first input terminal (TE1) through the reverse conduction switch diode (52) of the reverse conduction switch (50).

Thus, in the first drive mode, since both the first and second capacitors (31, 32) are charged, the voltage between the positive voltage side power supply line (21) and the negative voltage side power supply line (22) is approximately twice the voltage of each capacitor (31, 32). That is, the rectifier circuit (10) operates in a so-called voltage doubler rectification mode.

4(a) to 4(c) are diagrams corresponding to FIGS. 3(a) to 3(c) in the second drive mode.

In the second drive mode, the direction indicated by arrow AR3 in FIG. current flows to charge the first capacitor (31). At this time, a current flows from the first input terminal (TE1) to the first capacitor (31) through the first rectifier circuit diode (11). Further, a current flows from the first capacitor (31) to the second capacitor (32), and from the second capacitor (32) to the second input terminal (TE2 ) current flows.

In addition, in the second drive mode, in a part of the half cycle (HC2) in which the voltage of the second input terminal (TE2) is equal to or higher than the voltage of the first input terminal (TE1), the arrow AR4 in FIG. Current flows in the indicated direction to charge the first capacitor (31). At this time, a current flows from the second input terminal (TE2) to the first capacitor (31) through the third rectifier circuit diode (13). Further, a current flows from the first capacitor (31) to the second capacitor (32), and from the second capacitor (32) through the second rectifier circuit diode (12) to the first input terminal (TE1 ) current flows.

In the second drive mode of Embodiment 1, the rectifier circuit (10) operates in a so-called full-wave rectification mode in a steady state. When the voltage of the second capacitor (32) is approximately 0 or a positive value in a transient state, the voltage of the second capacitor (32) and the forward voltage of the second rectifier circuit diode (12) are combined. Since the voltage is higher than the forward voltage of the reverse conduction switch diode (52), the current does not flow through the path indicated by the arrow AR4, but flows through the reverse conduction switch diode (52) to the second capacitor (32). is not charging. However, the second capacitor (32) is discharged by the power supply from the second capacitor (32) to the electric motor (3), the voltage of the second capacitor (32) becomes a negative voltage close to 0, and the second The sum of the voltage of the capacitor (32) and the forward voltage of the second rectifier circuit diode (12) is smaller than the forward voltage of the reverse conduction switch diode (52). , the voltage of the second capacitor (32) stabilizes at a negative voltage close to 0, and the current begins to flow along the path of arrow AR4. Therefore, in the second drive mode, the DC voltage between the positive voltage side power line (21) and the negative voltage side power line (22) is approximately the same as the voltage of the first capacitor (31). Also, in the second drive mode, no current flows through the reverse conducting switch (50). The voltage of the second capacitor (32) is always a negative value close to zero.

Thus, in the first drive mode and the second drive mode, the output voltage of the rectifier circuit (10), that is, the voltage of the positive voltage side power line (21) with respect to the negative voltage side power line (22) It can be transitioned in different manners.

Therefore, according to the first embodiment, the reverse conduction switch (50) composed of one reverse conduction switch diode (52) and one bipolar transistor (51) is used for switching the rectification mode. Compared to the case of using a bidirectional switch having four diodes and one unidirectional switch as in Document 1, the number of elements can be reduced and the circuit scale can be reduced.

In addition, since the capacitor on the side of the negative voltage side power supply line (22), that is, the second capacitor (32) is a non-polar capacitor, the reverse conduction switch (50) is turned off to the second capacitor (32). A negative voltage can be applied when

(Embodiment 2)
FIG. 5 shows a power converter (1) according to Embodiment 2 of the present disclosure. In Embodiment 2, the first capacitor (31) is a non-polar capacitor, while the second capacitor (32) is a polar capacitor.

In addition, the reverse conduction switch (50) turns off the bipolar transistor (51) and directs from the first input terminal (TE1) to the connection point (CP) of the first and second capacitors (31, 32). It is connected so that current flows in one direction. That is, the collector of the bipolar transistor (51) is connected to the connection point (CP) of the first and second capacitors (31, 32), and the emitter of the bipolar transistor (51) is connected to the first input terminal (TE1). It is connected to the.

The anode of the reverse conduction switch diode (52) is connected to the first input terminal (TE1) and the emitter of the bipolar transistor (51). The cathode of the reverse conduction switch diode (52) is connected to the connection point (CP) of the first and second capacitors (31, 32) and the collector of the bipolar transistor (51).

Further, in Embodiment 2, the first drive mode is a predetermined ON state included in the half cycle (HC2) in which the voltage of the second input terminal (TE2) is equal to or higher than the voltage of the first input terminal (TE1). The second drive mode is a half cycle (HC2 ) to always turn off the reverse conduction switch (50). In the second embodiment, as in the first embodiment, the control section (60) always turns on the reverse conduction switch (50) in the first drive mode. Therefore, the predetermined ON period is the entire half cycle (HC2) during which the voltage of the second input terminal (TE2) is equal to or greater than the voltage of the first input terminal (TE1). On the other hand, in the second driving mode, the reverse conducting switch (50) is always turned off.

Since other configurations are the same as those of the first embodiment, the same configurations are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

In the second embodiment, as shown in FIG. 6, in the second driving mode, only the second capacitor (32) is charged, and the voltage of the first capacitor (31) is always a negative value close to 0. becomes.

Therefore, according to the second embodiment, since the capacitor on the positive voltage side power supply line (21) side, that is, the first capacitor (31) is a non-polar capacitor, the first capacitor (31) is reverse conductive. A negative voltage can be applied when the switch (50) is turned off.

(Embodiment 3)
FIG. 7 shows a power converter (1) according to Embodiment 3 of the present disclosure. In Embodiment 3, the second capacitor (32) is a polar capacitor. A negative voltage power line side diode (33) is connected in parallel to the second capacitor (32) with its cathode facing the positive electrode side of the second capacitor (32). The anode of the negative voltage power supply line side diode (33) is connected to the negative voltage power supply line (22), and the cathode of the negative voltage power supply line side diode (33) is connected to the first and second capacitors (31, 32). connected to the connection point (CP) of the

Since other configurations are the same as those of the first embodiment, the same configurations are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

FIGS. 9(a) to 9(c) show voltage values and current values of each part in the second drive mode of the power converter (1) of Embodiment 3. FIG. In FIG. 9(b), the rectifier circuit diode current is the current flowing through the second and fourth rectifier circuit diodes (12, 14) of the rectifier circuit (10).

In the power conversion device (1) of Embodiment 3, in the second drive mode, the voltage of the second input terminal (TE2) is equal to or higher than the voltage of the first input terminal (TE1) in a half cycle (HC2). Part of the current flows through two paths indicated by arrows AR5 and AR6 in FIG. The path indicated by the arrow AR5 is from the second input terminal (TE2) through the third rectifier circuit diode (13), the first capacitor (31), and the reverse conduction switch diode (52) in order to the first input terminal. is the path leading to the input terminal (TE1) of The path indicated by the arrow AR6 is from the second input terminal (TE2) through the third rectifier circuit diode (13), the inverter circuit (40), and the second rectifier circuit diode (12) in order to the first input terminal (TE2). is the path leading to the input terminal (TE1) of The reason why the current flows in the path of arrow AR5 is as follows. In the half cycle (HC2), before the current flows through the path of the arrow AR5, the voltage of the second capacitor (32) is a negative voltage lower than the forward voltage of the negative voltage power line side diode (33), A current flows along the path indicated by the arrow AR4 in FIG. When the second capacitor (32) continues to be charged while the current flows through the path of arrow AR4, the voltage of the second capacitor (32) and the forward voltage of the second rectifier circuit diode (12) The combined voltage becomes greater than the forward voltage of the reverse conduction switch diode (52), and at this point the current path is switched to the path of arrow AR5.

Further, in the second drive mode, the arrow AR7 and the arrow AR7 in FIG. 8 and The current flows through two paths indicated by arrows AR8. A path indicated by an arrow AR7 is from the first input terminal (TE1) to the first rectifier circuit diode (11), the first capacitor (31), the second capacitor (32), and the fourth rectifier circuit diode. (14) in order to reach the second input terminal (TE2). A path indicated by an arrow AR8 extends from the first input terminal (TE1) through the first rectifier circuit diode (11), the inverter circuit (40), and the fourth rectifier circuit diode (14) in order to the second input terminal (TE1). This is the path leading to the input terminal (TE2) of In the third embodiment, as shown in FIG. 9C, the absolute value of the reverse voltage applied to the second capacitor (32) is less than or equal to the forward voltage of the negative voltage power supply line diode (33). maintained at

Therefore, according to the third embodiment, a polar capacitor is used as the capacitor on the negative voltage side power supply line (22) side, that is, the second capacitor (32). , the capacitor (32) can be miniaturized. In addition, since the absolute value of the reverse voltage applied to the second capacitor (32) can be made equal to or less than the forward voltage of the negative voltage power line side diode (33), the absolute value of the second capacitor (32) It is possible to suppress failure of the second capacitor (32) due to application of a large reverse voltage.

(Embodiment 4)
FIG. 10 shows a power converter (1) according to Embodiment 4 of the present disclosure. In Embodiment 4, the first capacitor (31) is a polar capacitor. A positive voltage power line side diode (34) is connected in parallel to the first capacitor (31) with its cathode facing the positive electrode side of the first capacitor (31). The anode of the positive voltage power line side diode (34) is connected to the connection point (CP) of the first and second capacitors (31, 32), and the cathode of the positive voltage power line side diode (34) is connected to the positive voltage It is connected to the side power line (21).

Since other configurations are the same as those of the second embodiment, the same configurations are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

In the fourth embodiment, as shown in FIG. 11, in the second drive mode, the absolute value of the reverse voltage applied to the first capacitor (31) is the positive voltage power supply line diode (34). Maintained below the forward voltage.

Therefore, according to the fourth embodiment, since a polar capacitor is used as the capacitor on the positive voltage side power supply line (21) side, that is, the first capacitor (31), the first , the capacitor (31) can be miniaturized. In addition, since the absolute value of the reverse voltage applied to the first capacitor (31) can be made equal to or less than the forward voltage of the positive voltage power line side diode (34), the absolute value of the first capacitor (31) It is possible to suppress failure of the first capacitor (31) due to application of a large reverse voltage.

(Embodiment 5)
In Embodiment 5 of the present disclosure, the control section (60) can variably set the length of the ON period (T1) and the start timing based on input from the user or an external device.

Since other configurations are the same as those of the first embodiment, detailed description thereof will be omitted.

In FIG. 12, G1 is a half cycle (HC1) when the ON period (T1) is a part of the voltage of the first input terminal (TE1) equal to or higher than the voltage of the second input terminal (TE2). It shows the output voltage of the rectifier circuit (10). G2 is the same as the first embodiment, when the ON period (T1) is the entire half cycle (HC1) in which the voltage of the first input terminal (TE1) is equal to or higher than the voltage of the second input terminal (TE2). shows the output voltage of the rectifier circuit (10) of G3 is the rectifier circuit (10) when the ON period (T1) is not provided in the half cycle (HC1) in which the voltage of the first input terminal (TE1) is equal to or higher than the voltage of the second input terminal (TE2). Indicates the output voltage.

In the examples shown in FIGS. 13A and 13B, the ON period (T1) is a half cycle ( HC1). The start timing of the ON period (T1) is the start timing of the half cycle (HC1), that is, the timing when the voltage of the first input terminal (TE1) becomes equal to the voltage of the second input terminal (TE2). there is If the on-period (T1) is the part of the half-cycle (HC1) in which the voltage at the first input terminal (TE1) is greater than or equal to the voltage at the second input terminal (TE2), then during the on-period (T1), Only the second capacitor (32) is charged and the first capacitor (31) is not. On the other hand, in the half cycle (HC1) in which the voltage of the first input terminal (TE1) is equal to or higher than the voltage of the second input terminal (TE2), the period (Fig. At least part of T2 in the middle) charges both the first and second capacitors (31, 32).

Therefore, according to the fifth embodiment, by changing the length of the ON period (T1) (proportion of the half cycle (HC1)) or the start timing, the output of the rectifier circuit (10) in the first drive mode The mode of voltage transition can be changed.

(Embodiment 6)
FIG. 14 shows a power converter (1) according to Embodiment 6 of the present disclosure. In Embodiment 6, the reverse conducting switch (50) is composed of a MOSFET (metal-oxide-semiconductor field-effect transistor), that is, a unipolar transistor.

Since other configurations are the same as those of the first embodiment, the same configurations are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

Also in the sixth embodiment, the control section (60) always turns on the reverse conduction switch (50) in the first drive mode. That is, in the first drive mode, the control section (60) always keeps the reverse conduction during the half cycle (HC2) in which the voltage of the second input terminal (TE2) is equal to or higher than the voltage of the first input terminal (TE1). Execute the on control to turn on the switch (50). Therefore, during the ON control, the current flows in the channel of the reverse conducting switch (50) in the direction (current direction) from the first and second capacitors (31, 32) to the first input terminal (TE1). flows. In this way, the current can flow through the channel of the reverse conducting switch (50) during ON control, so power loss in the reverse conducting switch (50) can be reduced compared to the case where the current flows only through the body diode.

In the third embodiment, the reverse conducting switch ( 50) may be executed. As a result, when current flows from the connection point (CP) to the first input terminal (TE1) via the reverse conduction switch (50), for example, along the path indicated by the arrow AR5 in FIG. 7, the reverse conduction switch (50) channel to reduce power loss in the reverse conducting switch (50).

(Embodiment 7)
In Embodiment 7 of the present disclosure, as shown in FIGS. 15(a) and 15(b), the control section (60) controls that no current flows through the reverse conducting switch (50) in the first drive mode. When the first switching control to switch the reverse conducting switch (50) from the ON state to the OFF state, and when the reverse conducting switch (50) is turned on but current does not flow through the reverse conducting switch (50), reverse conducting Second switching control is performed to switch the switch (50) from the OFF state to the ON state.

Since other configurations are the same as those of the first embodiment, detailed description thereof will be omitted.

Therefore, according to Embodiment 7, the switching loss of the reverse conducting switch (50) can be reduced.

Further, in Embodiment 1 above, by switching the reverse conducting switch (50) from the on state to the off state when no current flows in the channel of the reverse conducting switch (50) which is in the ON state in the first drive mode, , the drive mode may be switched to the second drive mode. In this case, even if the reverse conduction switch (50) is turned on in the second drive mode, the reverse conduction switch (50) is turned on from the off state at the timing when the current does not flow through the channel of the reverse conduction switch (50). , the drive mode may be switched to the first drive mode. Thereby, the switching loss of the reverse conducting switch (50) can be reduced.

(Other embodiments)
In Embodiments 1 to 7 above, the control section (60) selects either one of the first and second drive modes based on an input from the user or an external device. The selection may be made based on the state of at least one of the phase AC power supply (2) and the electric motor (3). For example, it may be selected based on values related to the output power of the inverter circuit (40), such as the output power, input power, and input current of the inverter circuit (40). The selection may be made based on values related to the induced voltage of the motor (3), such as the duty ratio of the switching elements (41a to 46a) of (40), the input power of the inverter circuit (40), and the like. Alternatively, the selection may be made based on the power supply voltage.

Further, in Embodiments 1 to 7, the inverter circuit (40) converts the direct current input to the positive voltage power line (21) and the negative voltage power line (22) into alternating current and supplies the alternating current to the electric motor (3). is provided as a power conversion circuit, the DC/DC converter converts the direct current input to the positive voltage side power line (21) and the negative voltage side power line (22) into direct current and supplies it to the electric motor (3). It may be provided as a conversion circuit.

In Embodiment 5, both the length of the ON period (T1) and the start timing are variable, but only one of them may be variable.

Further, in the fifth embodiment, the control unit (60) sets the length of the ON period (T1) and the start timing based on the input from the user or the external device. It may be set based on the state of at least one of the phase AC power supply (2) and the electric motor (3). For example, it may be set based on values related to the output power of the inverter circuit (40), such as the output power, input power, and input current of the inverter circuit (40), or the rotation speed of the electric motor (3), the inverter circuit It may be set based on a value related to the induced voltage of the electric motor (3), such as the duty ratio of the switching elements (41a to 46a) of (40) and the input power of the inverter circuit (40). Alternatively, it may be set based on the power supply voltage. Thereby, the state of the transition of the output voltage of the rectifier circuit (10) can be changed to the first and the second drive mode.

Further, in the seventh embodiment, the control section (60) executes both the first switching control and the second switching control in the first drive mode, but may execute only one of them.

Although the embodiments have been described above, it will be appreciated that various changes in form and detail may be made without departing from the spirit and scope of the claims. Also, the embodiments and modifications described above may be appropriately combined or replaced as long as the functions of the object of the present disclosure are not impaired.

INDUSTRIAL APPLICATION This indication is useful as a power converter device provided with the rectifier circuit which converts the input alternating current supplied from a single-phase alternating current power supply into direct current.

1 power conversion device 2 single-phase AC power supply 3 motor (load)
10 rectifier circuit 21 positive voltage side power supply line
22 Negative voltage side power supply line 31 First capacitor
32 Second capacitor 33 Negative voltage power line side diode
34 positive voltage power line side diode
40 Inverter circuit (power conversion circuit)
50 reverse conduction switch
60 control unit TE1 first input terminal TE2 second input terminal CP connection point

Claims (8)

a positive voltage side power line (21) and a negative voltage side power line (22);
The input alternating current supplied from the single-phase alternating current power supply (2) to the first and second input terminals (TE1, TE2) is converted to direct current, and the positive voltage side power line (21) and the negative voltage side power line (22) are converted into direct current. ) and a rectifier circuit (10) that outputs to
first and second capacitors (31, 32) connected in series between the positive voltage power line (21) and the negative voltage power line (22);
a reverse conducting switch (50) having one end connected to the connection point (CP) of the first and second capacitors (31, 32) and the other end connected to the first input terminal (TE1); A power conversion device comprising: In the power converter according to claim 1,
When the reverse conduction switch (50) is connected so that current flows in the direction from the first input terminal (TE1) to the connection point (CP) in the OFF state, the first and second of the capacitors (31, 32), the capacitor (31) on the side of the positive voltage power supply line (21) is a non-polar capacitor,
When the reverse conduction switch (50) is connected so that current flows in the direction from the connection point (CP) to the first input terminal (TE1) in the OFF state, the first and second A power conversion device, wherein the capacitor (32) of the capacitors (31, 32) on the side of the negative voltage side power supply line (22) is a non-polar capacitor. In the power converter according to claim 1,
When the reverse conduction switch (50) is connected so that current flows in the direction from the first input terminal (TE1) to the connection point (CP) in the OFF state, the first and second Among the capacitors (31, 32) in the above, the capacitor (31) on the positive voltage side power supply line (21) side is a polar capacitor, and the capacitor (31) on the positive voltage side power supply line (21) side has a diode (34) are connected in parallel with their cathodes facing the positive side of the capacitor (31),
When the reverse conducting switch (50) is connected so that current flows in the direction from the connection point (CP) to the first input terminal (TE1) in the OFF state, the first and second Among the capacitors (31, 32), the capacitor (32) on the negative voltage side power line (22) side is a polar capacitor, and the capacitor (32) on the negative voltage side power line (22) side has a diode (33) is connected in parallel with its cathode facing the positive electrode side of the capacitor (32). In the power converter according to any one of claims 1 to 3,
a first drive mode in which the reverse conducting switch (50) is turned on during a predetermined ON period (T1) included in one half cycle of each cycle of the input alternating current;
a control unit (60) capable of controlling the reverse conducting switch (50) in a second drive mode in which the reverse conducting switch (50) is always turned off in the one half cycle of each cycle of the input alternating current; prepared,
When the reverse conducting switch (50) is connected so that the current flows in the current direction from the connection point (CP) to the first input terminal (TE1) in the OFF state, the one half cycle is a half cycle (HC1) in which the voltage of the first input terminal (TE1) is greater than or equal to the voltage of the second input terminal (TE2), while the reverse conducting switch (50) is in the OFF state and the When connected so that the current flows in the current direction from the first input terminal (TE1) to the connection point (CP), the one half period is the voltage of the second input terminal (TE2) is a half cycle (HC2) that is equal to or higher than the voltage of the first input terminal (TE1). In the power converter according to claim 4,
Further comprising a power conversion circuit (40) that converts direct current input to the positive voltage power line (21) and the negative voltage power line (22) into direct current or alternating current and supplies the converted power to a load,
The control unit selects one of the first and second drive modes based on the state of at least one of the power conversion circuit (40), the single-phase AC power supply (2), and the load (3). A power conversion device characterized by selecting either one and controlling the reverse conducting switch (50) in the selected drive mode. In the power conversion device according to claim 4 or 5,
A power converter, wherein at least one of the length of the ON period (T1) and the start timing is variable. In the power converter according to any one of claims 4 to 6,
The reverse conducting switch (50) is composed of a unipolar transistor,
The control section (60) performs on-control to turn on the reverse conducting switch (50) in the other half cycle of each cycle of the input alternating current,
A power converter, wherein a current flows through a channel of the reverse conducting switch (50) in the current direction during the ON control. In the power converter according to any one of claims 4 to 7,
The control section (60) performs first switching control for switching the reverse conducting switch (50) from an on state to an off state when no current is flowing through the reverse conducting switch (50), and the reverse conducting switch ( 50) is turned on, when no current flows through the reverse conducting switch (50), executing at least one of second switching control for switching the reverse conducting switch (50) from an off state to an on state. A power conversion device characterized by:

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