JP2018148604A - Rectification device, power supply device, motor device and air conditioning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rectification device or the like which suppresses the number of diodes having high-speed switching property while achieving a low loss.SOLUTION: A rectification device 100 comprises: a capacitance part 30 including capacitors C1 and C2 that are connected in series between terminals Out1 and Out2; and an intermediate potential setting part 20 which sets a potential at a connection point (j) between the capacitors C1 and C2. The intermediate potential setting part 20 includes a diode bridge part 20A and a series circuit of a switching element S1, an inductor L1, an inductor L2 and a switching element S2, and a connection point (g) between the inductors L1 and L2 is connected to the connection point (j) between the capacitors C1 and C2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rectifier, a power supply device, an electric motor device, and an air conditioner.

  2. Description of the Related Art In recent years, a rectifier (converter) that rectifies alternating current is connected to an inverter device, generates alternating current having a frequency different from the alternating frequency supplied to the rectifier, and is used for driving a motor or the like. Such motors are widely used in refrigerators, air conditioners and the like.

  Patent Document 1 discloses a rectifier circuit that rectifies an output voltage of an AC power supply, first and second capacitors connected in series that smooth the output of the rectifier circuit, and an AC power supply connected to the first and second capacitors. A converter circuit is described that includes a switch circuit that switches the connection between the capacitors and the AC power supply so that the output voltage is alternately applied repeatedly at a cycle shorter than the cycle of the AC power supply.

JP 2005-110491 A

By the way, in a rectifier having a diode bridge connected in parallel and having a step-up function using a switching element, the diode bridge requires a high-speed switching characteristic, which causes a cost increase.
An object of the present invention is to provide a rectifier and the like that suppresses the number of diodes having high-speed switching characteristics while achieving low loss.

  For this purpose, a rectifying device to which the present invention is applied includes a capacitance unit having a plurality of capacitors connected in series between two output terminals. And the rectification | straightening part which rectifies | straightens the alternating current supplied from the alternating current power supply connected and supplies between the two said output terminals of the said capacity | capacitance part is provided. Further, an intermediate potential setting unit that sets potentials at connection points between the plurality of capacitors is provided. The intermediate potential setting unit includes a series circuit of a first switching element, a first inductor, a second inductor, and a second switching element between input terminals of the AC power supply. A connection point between the first inductor and the second inductor is connected to a connection point between the plurality of capacitors.

  In such a rectifier, the intermediate potential setting unit includes a rectifier circuit connected to the AC power supply. A first free-wheeling diode provided between a connection point between the first switching element and the first inductor and an output terminal on a low voltage side of the capacitor; Furthermore, a second free-wheeling diode provided between a connection point between the second switching element and the second inductor and an output terminal on the high voltage side of the capacitor unit is included. A series circuit of the first switching element, the first inductor, the second inductor, and the second switching element is provided between a high voltage side and a low voltage side of the rectifier circuit. Yes.

  The first inductor and the second inductor are configured by a translink type having a common core.

  From another point of view, a power supply device to which the present invention is applied includes the rectifier device and an inverter device.

  Furthermore, from another viewpoint, the electric motor device to which the present invention is applied includes the power supply device and an electric motor driven by the power supply device.

  Furthermore, from another viewpoint, an air conditioner to which the present invention is applied includes the electric motor device.

  ADVANTAGE OF THE INVENTION According to this invention, the rectifier etc. which suppressed the number of the diodes which have a high-speed switching characteristic, achieving a low loss can be provided.

It is a figure which shows an example of the rectifier to which 1st Embodiment is applied. It is an example of the rectifier to which the first embodiment shown for comparison is not applied. It is another example of the rectifier to which the first embodiment shown for comparison is not applied. It is an example of the rectifier to which 2nd Embodiment is applied. It is an example of the rectifier to which the second embodiment shown for comparison is not applied.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
[First Embodiment]
FIG. 1 is a diagram illustrating an example of a rectifier 100 to which the first embodiment is applied.
The rectifier 100 according to the first embodiment is connected to a single-phase AC power source 200. The power source 200 is an example of an AC power source.
The rectifying device 100 includes a rectifying unit 10, an intermediate potential setting unit 20, and a capacitor unit 30.
The power supply 200 and the rectifying device 100 are connected to each other through terminals In1 and In2 that are input terminals. The rectifier 100 is connected to an external load (not shown) such as an inverter at terminals Out1 and Terminal2 which are output terminals. And the rectifier 100 outputs a DC voltage from between the terminal Out1 and the terminal Out2.

The rectifying unit 10 includes a diode bridge including four rectifying diodes D11, D12, D13, and D14. The diode bridge is configured such that a series connection of a rectifier diode D11 and a rectifier diode D12 and a series connection of a rectifier diode D13 and a rectifier diode D14 are connected in parallel.
A connection point a of the rectification diodes D11 and D12 connected in series is connected to the terminal In1, and a connection point b of the rectification diodes D13 and D14 connected in series is connected to the terminal In2.
Further, the cathodes of the rectifier diodes D11 and D13 are connected to the high voltage side wiring 41 connected to the terminal Out1, and the anodes of the rectification diodes D12 and D14 are connected to the low voltage side wiring 42 connected to the terminal Out2.
The direction of current flow through the rectifier diodes D11, D12, D13, and D14 is set in a direction from the low voltage side wiring 42 side toward the high voltage side wiring 41 side.

The intermediate potential setting unit 20 includes a diode bridge unit 20A and a switching unit 20B. The diode bridge unit 20A includes a diode bridge composed of four rectifier diodes D21, D22, D23, and D24. The switching unit 20B includes switching elements S1 and S2, inductors L1 and L2, freewheeling diodes D1 and D2, and protective diodes D3 and D4.
Here, the diode bridge unit 20A is an example of a rectifier circuit. The inductor L1 is an example of a first inductor, and the inductor L2 is an example of a second inductor. The switching element S1 is an example of a first switching element, and the switching element S2 is an example of a second switching element. The freewheeling diode D1 is an example of a first freewheeling diode, and the freewheeling diode D2 is an example of a second freewheeling diode.

The diode bridge portion 20A is configured by connecting in parallel a series connection of a rectifier diode D21 and a rectifier diode D22 and a series connection of a rectifier diode D23 and a rectifier diode D24.
A connection point d between the rectification diodes D21 and D22 connected in series is connected to the terminal In1, and a connection point d between the rectification diodes D23 and D24 connected in series is connected to the terminal In2.
Further, the cathodes of the rectifying diodes D21 and D23 are connected to the wiring 43, and the anodes of the rectifying diodes D22 and D24 are connected to the wiring 44.
The direction of current flow through the rectifier diodes D21, D22, D23, and D24 is set to a direction from the wiring 44 side to the wiring 43 side.

The switching unit 20B includes a series circuit in which the switching element S1, the inductor L1, the inductor L2, and the switching element S2 are connected in series in this order.
That is, one terminal of the inductor L1 is connected to the source of the switching element S1 (connection point h), and the other terminal of the inductor L1 is connected to one terminal of the inductor L2 (connection point g). The drain of the switching element S2 is connected to the other terminal of the inductor L2 (connection point i).
Further, the drain of the switching element S1 is connected to the wiring 43, and the source of the switching element S2 is connected to the wiring 44.

A protection diode D3 is connected in parallel to the switching element S1, and a protection diode D4 is connected in parallel to the switching element S2. The direction in which the currents of the protection diodes D3 and D4 flow is set to be opposite to the direction in which the current flows when the switching elements S1 and S2 are turned on.
The protection diodes D3 and D4 suppress a reverse current from flowing through the switching elements S1 and S2.

Further, the free-wheeling diode D1 has a cathode connected to a connection point h between the switching element S1 and the inductor L1, and an anode connected to the low-voltage side wiring.
On the other hand, the free-wheeling diode D2 has an anode connected to the connection point i between the inductor L2 and the switching element S2, and a cathode connected to the high-voltage side wiring 41.

The switching elements S1 and S2 may be any switching elements for high withstand voltage power, and field effect transistors, insulated gate bipolar transistors (IGBT), and the like can be applied.
The free-wheeling diodes D1 and D2 are so-called fast recovery diodes (fast recovery diodes) having high-speed switching characteristics. Note that other diodes other than the free-wheeling diodes D1 and D2 do not have to have a high-speed switching characteristic like a high-speed recovery diode. The other diodes are rectifier diodes D11, D12, D13, and D14 of the rectifier unit 10, rectifier diodes D21, D22, D23, and D24 of the diode bridge unit 20A, and protective diodes D3 and D4 of the switching unit 20B.

  The inductors L1 and L2 indicate the direction of the winding with a symbol. That is, the inductors L1 and L2 have the same winding direction and generate back electromotive force in the same direction.

Capacitance unit 30 includes capacitors C1 and C2 connected in series.
A connection point j between the capacitor C1 and the capacitor C2 is connected to a connection point g between the inductor L1 and the inductor L2 in the switching unit 20B of the intermediate potential setting unit 20. The side of the capacitor C1 not connected to the capacitor C2 is connected to the high voltage side wiring 41 at the connection point k, and the side of the capacitor C2 not connected to the capacitor C1 is connected to the low voltage side wiring 42 at the connection point l. Has been.
The high voltage side wiring 41 is connected to the terminal Out1, and the low voltage side wiring 42 is connected to the terminal Out2.
In FIG. 1, the capacitors C1 and C2 are electrolytic capacitors, and their polarities are indicated by symbols. However, the capacitors C1 and C2 may be film capacitors or ceramic capacitors.

  The inductors L1 and L2 are preferably a translink type having a common core. If it is a trans-link type, it is possible to reduce the size and cost by using a common core.

Next, the operation of the rectifier 100 will be described.
A single-phase alternating current is applied between the terminal In1 and the terminal In2 of the rectifier 100.
The switching elements S1 and S2 of the rectifier 100 are switched at a frequency (period) higher than the single-phase AC frequency by a drive circuit (not shown). For example, the switching elements S1 and S2 are switched at 20 kHz with respect to a single-phase AC frequency of 60 Hz.

The switching duty ratio for the switching element S1 is set by the voltage between both terminals of the capacitor C2. The switching duty ratio for the switching element S2 is set by the voltage between both terminals of the capacitor C1, or the alternating current waveform is a waveform that satisfies the harmonic standards while supplying sufficient power to the load. Is set to be
Note that the duty ratio is a ratio of a period in the on state to a repetition cycle of the on state and the off state.

When the potential of the terminal In1 is higher than the potential of the terminal In2, a current flows through a path from the terminal In1 to the terminal In2 via the rectifier diode D11, the capacitor C1, the capacitor C2, and the rectifier diode D14.
When the potential of the terminal In1 is lower than the potential of the terminal In2, a current flows through a path from the terminal In2 to the terminal In1 via the rectifier diode D13, the capacitor C1, the capacitor C2, and the rectifier diode D12. In this way, the capacitors C1 and C2 of the capacitor unit 30 are charged.

Next, the case where switching element S1, S2 is switched is demonstrated.
(When the potential of the terminal In1 is higher than the potential of the terminal In2)
First, the case where the potential of the terminal In1 is higher than the potential of the terminal In2 will be described.
It is assumed that the switching element S1 is on and the switching element S2 is off. Then, a current flows through a path from the terminal In1 to the terminal In2 via the rectifier diode D21, the switching element S1, the inductor L1, the capacitor C2, and the rectifier diode D14.
In addition, energy is stored in the inductor L1 when a current flows. At this time, the free-wheeling diode D1 is in a reverse bias state (hereinafter referred to as reverse bias) and no current flows.

  Here, when the ON switching element S1 is turned off, the energy stored in the inductor L1 is released. At this time, the free-wheeling diode D1 is in a forward bias state (hereinafter referred to as a forward bias). That is, a current flows in a path from the connection point g of the inductor L1 to the connection point h of the capacitor C2, the free wheel diode D1, and the inductor L1. As a result, the capacitor C2 is further charged so that the potential at the connection point j is higher than the potential at the connection point l (terminal Out2).

On the other hand, it is assumed that the switching element S1 is off and the switching element S2 is on. Then, a current flows through a path from the terminal In1 to the terminal In2 via the rectifier diode D11, the capacitor C1, the inductor L2, the switching element S2, and the rectifier diode D24. As a result, charging is performed such that the potential at the connection point k (terminal Out1) is higher than the potential at the connection point j.
In addition, energy is stored in the inductor L2 when a current flows. At this time, the freewheeling diode D2 is in a reverse bias state and no current flows.

  Here, when the ON switching element S2 is turned off, a counter electromotive force is generated in the inductor L2, and the stored energy is released. At this time, the free-wheeling diode D2 is in a forward bias state. That is, a current flows in a path from the connection point i of the inductor L2 to the connection point g of the free wheeling diode D2, the capacitor C1, and the inductor L2. Thus, the capacitor C1 is further charged so that the potential at the connection point k (terminal Out1) is higher than the potential at the connection point j.

(When the potential of the terminal In1 is lower than the potential of the terminal In2)
Next, a case where the potential of the terminal In1 is lower than the potential of the terminal In2 will be described.
It is assumed that the switching element S1 is on and the switching element S2 is off. Then, a current flows through a path from the terminal In2 to the terminal In1 via the rectifier diode D23, the switching element S1, the inductor L1, the capacitor C2, and the rectifier diode D12. As a result, the capacitor C2 is charged such that the potential at the connection point j is higher than the potential at the connection point l (terminal Out2).
In addition, energy is stored in the inductor L1 when a current flows. At this time, the freewheeling diode D1 is in a reverse bias state and no current flows.

  Here, when the on-switching element S1 is turned off, a back electromotive force is generated in the inductor L1 and the stored energy is released as in the case where the potential of the terminal In1 is higher than the potential of the terminal In2. At this time, the free-wheeling diode D1 is in a forward bias state, and a current flows through a path from the connection point g of the inductor L1 to the connection point h of the capacitor C2, the free-wheeling diode D1, and the inductor L1. As a result, the capacitor C2 is further charged so that the potential at the connection point j is higher than the potential at the connection point l (terminal Out2).

On the other hand, it is assumed that the switching element S1 is off and the switching element S2 is on. Then, a current flows through a path from the terminal In2 to the terminal In1 via the rectifier diode D13, the capacitor C1, the inductor L2, the switching element S2, and the rectifier diode D22. As a result, charging is performed such that the potential at the connection point k (terminal Out1) is higher than the potential at the connection point j.
In addition, energy is stored in the inductor L2 when a current flows. At this time, the freewheeling diode D2 is in a reverse bias state and no current flows.

  Here, when the on-switching element S2 is turned off, a counter electromotive force is generated in the inductor L2 and the stored energy is released as in the case where the potential of the terminal In1 is higher than the potential of the terminal In2. At this time, the free-wheeling diode D2 is in a forward bias state. That is, a current flows in a path from the connection point i of the inductor L2 to the connection point g of the free wheeling diode D2, the capacitor C1, and the inductor L2. As a result, the capacitor C1 is further charged so that the potential at the connection point k (terminal Out1) is higher than the potential at the connection point j.

  As described above, a sum voltage of the voltage between the terminals of the capacitor C1 and the voltage between the terminals of the capacitor C2 is generated between the terminal Out1 (connection point k) and the terminal Out2 (connection point 1). By repeating the above operation, the voltage between the terminal Out1 and the terminal Out2 can be controlled to an arbitrary step-up ratio of 1 or more.

Here, switching characteristics required for the diode will be described.
The diode has a characteristic of passing a current with a forward bias and blocking the current with a reverse bias.
However, when the diode is changed from the forward bias to the reverse bias, carriers accumulated during the forward bias flow into a state of flowing as a reverse current. Therefore, when the diode is alternately switched between the forward bias and the reverse bias at high speed, if the period during which the reverse current flows (recovery time or reverse recovery time) is long, the function of blocking the current flow as the diode is lost. For this reason, power consumption increases and efficiency decreases. In addition, the cooler for heat dissipation is costly.
Therefore, a high-speed recovery diode (fast recovery diode) with a short recovery time is used as a diode that switches between forward bias and reverse bias at high speed.
The fast recovery diode is more expensive than a so-called general rectifying diode.

  In the rectifier 100 to which the first embodiment is applied, as described above, the freewheeling diodes D1 and D2 correspond to the on / off of the switching elements S1 and S2, as described below. Reverse bias is switched. Therefore, the freewheeling diodes D1 and D2 are required to be fast recovery diodes.

That is, it is assumed that the switching element S2 is on when the potential of the terminal In1 is higher than the potential of the terminal In2. Then, the capacitor C1 is charged through a path from the terminal In1 to the terminal In2 via the rectifier diode D11, the capacitor C1, the inductor L2, the switching element S2, and the rectifier diode D24. At this time, the rectifier diode D11 is forward biased.
It is assumed that the switching element S2 is turned off from on. Then, the energy stored in the inductor L2 has no path other than charging the capacitor C1 through the freewheeling diode D2 and returning to the connection point g. That is, it is not necessary that the diodes other than the freewheeling diode D2 are fast recovery diodes.

  Further, it is assumed that the switching element S1 is turned off from on. Then, the energy stored in the inductor L1 passes through the freewheeling diode D1, charges the capacitor C2, and has no path other than returning to the connection point h. That is, it is not necessary that the diodes other than the freewheeling diode D1 are fast recovery diodes.

  As described above, in the rectifier 100 to which the first embodiment is applied, the inductors L1 and L2 are used for the switching unit 20B of the intermediate potential setting unit 20. Thus, the free-wheeling diodes D1 and D2 only need to be fast recovery diodes, and the other rectifier diodes D11 to D14 and D21 to D24 do not need to be fast recovery diodes.

FIG. 2 is an example of the rectifier 101 to which the first embodiment shown for comparison is not applied. The same configurations as those of the rectifying device 100 to which the first embodiment shown in FIG. 1 is applied are denoted by the same reference numerals, description thereof is omitted, and different portions will be described.
The rectifying device 101 includes an inductor L3 between the terminal In1 and the connection point a of the rectifying unit 10.
The rectifier 101 does not include the inductors L1 and L2 and the free-wheeling diodes D1 and D2 included in the rectifier 100 to which the first embodiment is applied in the intermediate potential setting unit 20. Note that an inductor L3 is provided on one of the lines to which single-phase alternating current is supplied from the power source 200.

Next, the operation of the rectifier 101 will be described.
A single-phase alternating current is applied between the terminal In1 and the terminal In2 of the rectifier 101.
When the potential of the terminal In1 is higher than the potential of the terminal In2, a current flows through a path from the terminal In1 to the terminal In2 via the rectifier diode D11, the capacitor C1, the capacitor C2, and the rectifier diode D14.
When the potential of the terminal In1 is lower than the potential of the terminal In2, a current flows through a path from the terminal In2 to the terminal In1 via the rectifier diode D13, the capacitor C1, the capacitor C2, and the rectifier diode D12. In this way, the capacitors C1 and C2 of the capacitor unit 30 are charged.

Next, the case where switching element S1, S2 is switched is demonstrated.
(When the potential of the terminal In1 is higher than the potential of the terminal In2)
First, the case where the potential of the terminal In1 is higher than the potential of the terminal In2 will be described.
It is assumed that the switching element S1 is on and the switching element S2 is off. Then, a current flows through a path from the terminal In1 to the terminal In2 via the inductor L3, the rectifier diode D21, the switching element S1, the capacitor C2, and the rectifier diode D14. As a result, the capacitor C2 is charged such that the potential at the connection point j is higher than the potential at the connection point l (terminal Out2).

  On the other hand, it is assumed that the switching element S1 is off and the switching element S2 is on. Then, a current flows through a path from the terminal In1 to the terminal In2 via the inductor L3, the rectifier diode D11, the capacitor C1, the switching element S2, and the rectifier diode D24. As a result, the capacitor C1 is charged such that the potential at the connection point k (terminal Out1) is higher than the potential at the connection point j.

(When the potential of the terminal In1 is lower than the potential of the terminal In2)
Next, a case where the potential of the terminal In1 is lower than the potential of the terminal In2 will be described.
It is assumed that the switching element S1 is on and the switching element S2 is off. Then, a current flows through a path from the terminal In2 to the terminal In1 via the rectifier diode D23, the switching element S1, the capacitor C2, the rectifier diode D12, and the inductor L3. As a result, the capacitor C2 is charged such that the potential at the connection point j is higher than the potential at the connection point l (terminal Out2).

  On the other hand, it is assumed that the switching element S1 is off and the switching element S2 is on. Then, a current flows through a path from the terminal In2 to the terminal In1 via the rectifier diode D13, the capacitor C1, the switching element S2, the rectifier diode D22, and the inductor L3. As a result, the capacitor C1 is charged such that the potential at the connection point k (terminal Out1) is higher than the potential at the connection point j.

  As described above, a sum voltage of the voltage between the terminals of the capacitor C1 and the voltage between the terminals of the capacitor C2 is generated between the terminal Out1 and the terminal Out2. The maximum value of this sum voltage is twice the voltage between the terminal In1 and the terminal In2.

Here, switching characteristics required for the diode will be described.
It is assumed that the switching element S2 is on when the potential of the terminal In1 is higher than the potential of the terminal In2. Then, the capacitor C1 is charged through a path from the terminal In1 to the terminal In2 via the inductor L3, the rectifier diode D11, the capacitor C1, the switching element S2, and the rectifier diode D24. Thereafter, when the switching element S2 is turned off from on, the power charged in the inductor L3 returns to the inductor L3 through the rectifier diode D11, capacitors C1, C2, and rectifier diode D14. At this time, the rectifier diodes D11 and D14 are forward biased.
Next, when the switching element S1 is switched from OFF to ON, the electric charge accumulated in the capacitor C1 is switched from the capacitor C1 (connection point k) together with the switching element S1 to ON from the rectifier diodes D11, D21, the switching element S1, It tries to return to the capacitor C1 (connection point j) through the point g. Since the rectifier diode D11 is in the forward bias state, the rectifier diode D11 is required to be a fast recovery diode because it is instantaneously reverse biased.

  Similarly, when the switching element S2 is switched from OFF to ON, the electric charge accumulated in the capacitor C2 is switched from the capacitor C2 (connection point j) together with the switching element S2 being turned on to the connection point g, switching element S2, and rectifier diode D24. Through the rectifier diode D14 and return to the capacitor C2 (connection point 1). Since the rectifier diode D14 is in the forward bias state, the rectifier diode D14 is required to be a fast recovery diode because it is instantaneously reverse biased.

  When the potential at the terminal In1 is lower than the potential at the terminal In2, the rectifier diodes D12 and D13 change from forward bias to reverse bias. Therefore, the rectifier diodes D12 and D13 are required to be fast recovery diodes.

  That is, in the rectifier 101 to which the first embodiment is not applied, the four diodes of the rectifier diodes D11, D12, D13, and D14 are required to be fast recovery diodes.

FIG. 3 is another example of the rectifier 102 to which the first embodiment shown for comparison is not applied. The same configurations as those of the rectifying device 100 to which the first embodiment shown in FIG. 1 is applied are denoted by the same reference numerals, description thereof is omitted, and different portions will be described.
The rectifier 102 includes an inductor L4 between the terminal In1 and the connection point a of the rectification unit 10, and includes an inductor L5 between the terminal In2 and the connection point b of the rectification unit 10.
The rectifier 102 does not include the diode bridge unit 20A in the intermediate potential setting unit 20 of the rectifier 100 to which the first embodiment is applied in the intermediate potential setting unit 20. Further, the intermediate potential setting unit 20 of the rectifier 102 does not include the inductors L1 and L2 and the free wheel diodes D1 and D2 in the switching unit 20B of the rectifier 100 to which the first embodiment is applied. The drain of the switching element S1 is connected to the high voltage side wiring 41, and the source of the switching element S2 is connected to the low voltage side wiring 42. The source of the switching element S1 and the drain of the switching element S2 are connected.

On the other hand, the capacity unit 30 of the rectifier 102 includes free-wheeling diodes D5 and D6. The connection point k of the capacitor C1 is connected to the high voltage side wiring 41 via the freewheeling diode D5, and the connection point l of the capacitor C2 is connected to the low voltage side wiring 42 via the freewheeling diode D6. Yes. The free wheeling diode D5 is connected in the direction in which current flows from the high-voltage side wiring 41 to the connection point k, and the free-wheeling diode D6 is connected in the direction in which current flows from the connection point 1 to the low-voltage side wiring 42.
The other configuration is the same as that of the rectifier 100 to which the first embodiment shown in FIG. 1 is applied, and thus the same reference numerals are given and the description thereof is omitted.

Next, the operation of the rectifier 102 will be described.
A single-phase alternating current is applied between the terminal In1 and the terminal In2 of the rectifier 102.
When the potential at the terminal In1 is higher than the potential at the terminal In2, the terminal In1 is passed through the inductor L4, the rectifier diode D11, the freewheeling diode D5, the capacitor C1, the capacitor C2, the freewheeling diode D6, the rectifier diode D14, and the inductor L5. Current flows along the path leading to In2.
When the potential at the terminal In1 is lower than the potential at the terminal In2, the terminal In2 passes through the inductor L5, the rectifier diode D13, the freewheeling diode D5, the capacitor C1, the capacitor C2, the freewheeling diode D6, the rectifier diode D12, and the inductor L4. Thus, a current flows along the path to the terminal In1. In this way, the capacitors C1 and C2 of the capacitor unit 30 are charged.

(When the potential of the terminal In1 is higher than the potential of the terminal In2)
Next, the case where switching element S1, S2 is switched is demonstrated.
First, the case where the potential of the terminal In1 is higher than the potential of the terminal In2 will be described.
It is assumed that the switching element S1 is on and the switching element S2 is off. Then, a current flows through a path from the terminal In1 to the terminal In2 via the inductor L4, the rectifier diode D11, the switching element S1, the capacitor C2, the diode D6, the rectifier diode D14, and the inductor L5. As a result, the capacitor C2 is charged such that the potential at the connection point j is higher than the potential at the connection point l (terminal Out2).

  On the other hand, it is assumed that the switching element S1 is off and the switching element S2 is on. Then, a current flows through a path from the terminal In1 to the terminal In2 via the inductor L4, the rectifier diode D11, the freewheeling diode D5, the capacitor C1, the switching element S2, the rectifier diode D14, and the inductor L5. As a result, the capacitor C1 is charged such that the potential at the connection point k (terminal Out1) is higher than the potential at the connection point j.

(When the potential of the terminal In1 is lower than the potential of the terminal In2)
Next, a case where the potential of the terminal In1 is lower than the potential of the terminal In2 will be described.
It is assumed that the switching element S1 is on and the switching element S2 is off. Then, a current flows through a path from the terminal In2 to the terminal In1 via the inductor L5, the rectifier diode D13, the switching element S1, the capacitor C2, the diode D6, the rectifier diode D12, and the inductor L4. As a result, the capacitor C2 is charged such that the potential at the connection point j is higher than the potential at the connection point l (terminal Out2).

  On the other hand, it is assumed that the switching element S1 is off and the switching element S2 is on. Then, a current flows along a path from the terminal In2 to the inductor L5, the rectifier diode D13, the freewheeling diode D5, the capacitor C1, the switching element S2, the rectifier diode D12, and the inductor L4. As a result, the capacitor C1 is charged such that the potential at the connection point k (terminal Out1) is higher than the potential at the connection point j.

  As described above, a sum voltage of the voltage between the terminals of the capacitor C1 and the voltage between the terminals of the capacitor C2 is generated between the terminal Out1 and the terminal Out2. The maximum value of this sum voltage is twice the voltage between the terminal In1 and the terminal In2.

Here, switching characteristics required for the diode will be described.
It is assumed that the switching element S2 is on when the potential of the terminal In1 is higher than the potential of the terminal In2. Then, the capacitor C1 is charged through a path from the terminal In1 to the terminal In2 via the inductor L4, the rectifier diode D11, the freewheeling diode D5, the capacitor C1, the switching element S2, the rectifier diode D14, and the inductor L5. Thereafter, when the switching element S2 is turned off from on, the power charged in the inductor L4 returns to the inductor L4 through the rectifier diode D11, the freewheeling diode D5, the capacitors C1 and C2, the freewheeling diode D6, and the rectifier diode D14. At this time, the freewheeling diodes D5 and D6 are forward biased. The same applies to the power charged in the inductor L5.

  Next, when the switching element S1 is turned on from the off state, the electric charge accumulated in the capacitor C1 is transferred from the capacitor C1 (connection point k) together with the switching element S1 to turn on from the freewheeling diode D5, the switching element S1, and the connection point g. And attempt to return to the capacitor C1 (connection point j). Since the free-wheeling diode D5 is in the forward bias state, it is instantaneously reverse-biased. Therefore, the free-wheeling diode D5 is required to be a fast recovery diode.

  Similarly, when the switching element S2 is turned on from the off state, the electric charge accumulated in the capacitor C2 is switched from the capacitor C2 (connection point j) together with the switching element S2 to the on state, through the switching element S2 and the freewheeling diode D6. Attempt to return to C2 (connection point l). Since the free-wheeling diode D6 is in a forward bias state, it is instantaneously reverse-biased. Therefore, the free-wheeling diode D6 is required to be a fast recovery diode.

  That is, in the rectifier 102 to which the first embodiment is not applied, the free wheel diodes D5 and D6 are required to be fast recovery diodes, and the other rectifier diodes D11 to D14 do not need to be fast recovery diodes. .

  As described above, in the rectifier 101 to which the first embodiment is not applied, the four diodes (rectifier diodes D11 to D14) are required to be fast recovery diodes. On the other hand, in the rectifier 102 to which the first embodiment is not applied, the two diodes (freewheel diodes D5 and D6) are required to be fast recovery diodes. Therefore, the rectifying device 102 requires less (restricted) the number of fast recovery diodes than the rectifying device 101.

However, in the rectifier 102, the capacitor C1 is charged with a current passing through at least two diodes. For example, when the potential of the terminal In1 is higher than the potential of the terminal In2, and when the switching element S1 is off and the switching element S2 is on, the current flows from the terminal In1 to the capacitor via the rectifier diode D11 and the freewheeling diode D5. Supplied to C1. Further, the electric power stored in the inductor L4 is supplied to the capacitors C1 and C2 via the rectifier diode D11 and the freewheeling diode D5.
The greater the number of diodes through which current passes, the greater the loss.
In addition, the free-wheeling diodes D5 and D6 that are high-speed recovery diodes are required to have a large current capacity, resulting in an increase in cost.

On the other hand, the rectifier 100 to which the first embodiment is applied is required to have two diodes (freewheel diodes D1 and D2) as fast recovery diodes, like the rectifier 102.
However, in the rectifier 100, the capacitor C1 is charged with a current passing through one diode. For example, when the potential of the terminal In1 is higher than the potential of the terminal In2, and when the switching element S1 is off and the switching element S2 is on, current is supplied from the terminal In1 to the capacitor C1 via the rectifier diode D11. The Further, the electric power stored in the inductor L2 is supplied to the capacitor C1 only via the freewheeling diode D2.
That is, the rectifying device 100 has a smaller loss and higher efficiency than the rectifying device 102. Note that the rectifying device 100 has a smaller loss and improved efficiency than the rectifying device 101.
In addition, the free-wheeling diodes D1 and D2 that are high-speed recovery diodes are only required to flow a current for circulating the power stored in the inductors L1 and L2, and are not required to have a large current capacity. Therefore, the rectifier 100 is reduced in cost compared to the rectifier 102.

  The capacitor 30 includes the capacitors C1 and C2, but may include three or more capacitors connected in series. A predetermined connection point between the capacitors may be a connection point j and may be connected to the connection point g of the intermediate potential setting unit 20.

[Second Embodiment]
The rectifier 100 to which the first embodiment is applied is connected to a single-phase AC power source 200.
On the other hand, the rectifier 110 to which the second embodiment is applied is connected to a three-phase AC power source 300. The power supply 300 is another example of an AC power supply.
FIG. 4 is an example of the rectifier 110 to which the second embodiment is applied. In addition, the part similar to the rectifier 100 to which 1st Embodiment is applied attaches | subjects the same code | symbol, description is abbreviate | omitted, and a different part is demonstrated.
The rectifying device 110 includes a rectifying unit 10, an intermediate potential setting unit 20, and a capacitor unit 30.
The power supply 300 and the rectifier 110 are connected by a terminal In1, a terminal In2, and a terminal In3. The rectifier 110 is connected to an external load (not shown) such as an inverter at a terminal Out1 and a terminal Out2. The rectifier 110 outputs a DC voltage from between the terminal Out1 and the terminal Out2.

The rectifying unit 10 includes a diode bridge including six rectifying diodes D11, D12, D13, D14, D15, and D16. In the diode bridge, a series connection of a rectifier diode D11 and a rectifier diode D12, a series connection of a rectifier diode D13 and a rectifier diode D14, and a series connection of a rectifier diode D15 and a rectifier diode D16 are connected in parallel.
A connection point a of the rectification diodes D11 and D12 connected in series is connected to the terminal In1, and a connection point b of the rectification diodes D13 and D14 connected in series is connected to the terminal In2. Furthermore, the connection point c of the rectifier diodes D15 and D16 connected in series is connected to the terminal In3.
The cathodes of the rectifier diodes D11, D13, and D15 are connected to the high-voltage side wiring 41, and the anodes of the rectifier diodes D12, D14, and D16 are connected to the low-voltage side wiring 42 connected to the terminal Out2.
The direction of current flow through the rectifier diodes D11, D12, D13, D14, D15, and D16 is set to a direction from the low voltage side wiring 42 side toward the high voltage side wiring 41 side.

  The intermediate potential setting unit 20 includes a diode bridge unit 20A and a switching unit 20B. The diode bridge unit 20A includes six rectifier diodes D21, D22, D23, D24, D25, and D26. The switching unit 20B includes switching elements S1 and S2, inductors L1 and L2, freewheeling diodes D1 and D2, and protective diodes D3 and D4.

In the diode bridge portion 20A, a series connection of a rectifier diode D21 and a rectifier diode D22, a series connection of a rectifier diode D23 and a rectifier diode D24, and a series connection of a rectifier diode D25 and a rectifier diode D26 are connected in parallel. Yes.
A connection point d between the rectification diodes D21 and D22 connected in series is connected to the terminal In1, and a connection point e between the rectification diodes D23 and D24 connected in series is connected to the terminal In2. Furthermore, the connection point f of the rectifier diodes D25 and D26 connected in series is connected to the terminal In2.
Furthermore, the cathodes of the rectifier diodes D21, D23, and D25 are connected to the wiring 43, and the anodes of the rectifier diodes D22, D24, and D26 are connected to the wiring 44.
The direction of current flow through the rectifier diodes D21, D22, D23, D24, D25, and D26 is set to a direction from the wiring 44 side to the wiring 43 side.

The switching unit 20B is the same as the rectifier 100 to which the first embodiment is applied. Therefore, the description is omitted.
The capacity unit 30 is the same as the rectifier 100 to which the first embodiment is applied. Therefore, the description is omitted.

Since the operation of the rectifier 110 to which the second embodiment is applied is the same as that described in the rectifier 100 to which the first embodiment is applied, the description thereof is omitted.
Even in the rectifier 110 to which the second embodiment is applied, the two free-wheeling diodes D1 and D2 are required to be high-speed recovery diodes having high-speed switching characteristics.

FIG. 5 is an example of a rectifier 111 to which the second embodiment shown for comparison is not applied.
The rectifier 111 does not include the inductors L1 and L2 and the free-wheeling diodes D1 and D2 included in the rectifier 110 to which the second embodiment is applied in the intermediate potential setting unit 20. In addition, inductors L6, L7, and L8 are provided in the wiring to which the three-phase alternating current is supplied from the power source 300.
Since the operation of the rectifier 111 to which the second embodiment is not applied is the same as that described in the rectifier 101 to which the first embodiment is not applied, the description thereof is omitted.
In the rectifier 111 to which the second embodiment is not applied, six rectifier diodes D11, D12, D13, D14, D15, and D16 of the rectifier 10 are required to be fast recovery diodes.

As described above, in the rectifier 110 to which the second embodiment is applied, the number of fast recovery diodes is suppressed from six to two compared to the rectifier 111 to which the second embodiment is not applied. Is done. Furthermore, in the rectifier 110 to which the second embodiment is applied, the number of inductors is suppressed from three to two.
Therefore, in the rectifier 110 to which the second embodiment is applied, the cost is reduced and an increase in the area for mounting is suppressed.

  The rectifier 111 corresponds to the rectifier 101 to which the first embodiment is not applied, but may be a rectifier configured to correspond to the rectifier 102 to which the first embodiment is not applied. The same.

  The three-phase AC power supply 300 shown in FIGS. 3 and 4 is a star connection, but may be a ring (delta) connection.

  The rectifier 100 to which the first embodiment is applied and the rectifier 110 to which the second embodiment is applied constitute a power supply device in combination with an inverter device. Further, the power supply device constitutes an electric motor device in combination with an electric motor driven by the power supply device. Furthermore, the electric motor device is used for an air conditioner.

DESCRIPTION OF SYMBOLS 10 ... Rectification part, 20 ... Intermediate potential setting part, 20A ... Diode bridge part, 20B ... Switching part, 30 ... Capacitor part, 41 ... High voltage side wiring, 42 ... Low voltage side wiring, 43, 44 ... Wiring, 100, 101, 102, 110, 111 ... rectifier, 200, 300 ... power supply, D1, D2, D5, D6 ... freewheeling diode, D11-D16, D21-D26 ... rectifier diode, D3, D4 ... protection diode, L1, L2, L3, L4, L5, L6, L7, L8 ... inductor, S1, S2 ... switching element

Claims (6)

A capacitance unit having a plurality of capacitors connected in series between two output terminals;
A rectification unit that rectifies alternating current supplied from a connected alternating-current power supply and supplies between the two output terminals of the capacitance unit;
An intermediate potential setting unit for setting a potential at a connection point between the plurality of capacitors,
The intermediate potential setting unit includes:
Including a series circuit of a first switching element, a first inductor, a second inductor, and a second switching element between input terminals of the AC power supply;
A rectifying device in which a connection point between the first inductor and the second inductor is connected to a connection point between the plurality of capacitors. The intermediate potential setting unit includes:
A rectifier circuit connected to the AC power source;
A first free-wheeling diode provided between a connection point between the first switching element and the first inductor, and an output terminal on a low voltage side of the capacitor unit;
A second free-wheeling diode provided between a connection point between the second switching element and the second inductor and an output terminal on the high voltage side of the capacitor unit,
A series circuit of the first switching element, the first inductor, the second inductor, and the second switching element is provided between a high voltage side and a low voltage side of the rectifier circuit. The rectifier according to claim 1.   3. The rectifier according to claim 1, wherein the first inductor and the second inductor are configured in a translink type having a common core. 4. The rectifier according to any one of claims 1 to 3,
A power supply device comprising an inverter device. A power supply device according to claim 4,
An electric motor device comprising: an electric motor driven by the power supply device.   An air conditioner comprising the electric motor device according to claim 5.

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