JP5381005B2 - Power conversion system - Google Patents

Description

  The present invention provides a first power conversion device in which two or more switching elements are connected in series with one or more switching elements as one arm, and the switching arms by converting power from a power storage device to power. The present invention relates to a power conversion system having a second power conversion device to be supplied to both ends.

There are many troubles caused by conduction noise and radiation noise generated by the power converter. For this reason, the noise generated by the power converter is subject to regulation by CISPR (International Committee for Radio Interference) and VCCI (Council for Voluntary Control of Radio Interferences such as Information Processing Devices).
FIG. 9 shows a speed control system of a three-phase motor as a specific example of the power converter, and simultaneously illustrates a noise terminal voltage measurement system of a general-purpose inverter. The configuration shown in FIG. 9 includes a three-phase power supply 1, a pseudo power supply network (LISN) 2 for impedance matching, a diode rectifier 3, a smoothing capacitor 4, an IGBT as a switching element, and a diode connected in reverse parallel thereto. Is a general-purpose inverter 5 provided with three switching arms with three arms connected in series with two arms connected in series, a cable 6 derived from the middle point of each switching arm of the general-purpose inverter 5, and switching connected to this cable 6 A spectrum analyzer (interference wave intensity) that includes a three-phase motor 7 that controls speed by controlling the drive current by switching the elements, and further acquires the terminal voltage of the impedance element connected to the ground line from each phase line in the LISN 2 8) is provided.

In the case of a general-purpose inverter, it is generally said that a common mode component (a component having a high-frequency leakage current flowing through a stray capacitance as a noise source) is dominant noise. A common mode equivalent circuit shown in FIG. 10 is often used as a method for simply expressing the operation of the high-frequency leakage current.
In FIG. 10, the power converter shown in FIG. 9 has the neutral point potential fluctuation E (V), the leakage current path inductance L (H), the leakage current path resistance R (Ω), and the stray capacitance C (F). It is simply displayed as a series circuit. Here, FIG. 10 is a configuration in which the model of FIG. 9 is greatly simplified, but a model that takes into account the stray capacitance of the cable and the stray capacitance of the IGBT module can also be configured. However, in any model, the high-frequency leakage current is defined as the current flowing through the ground wire, and therefore flows through the stray capacitance formed inside the evaluation device (general-purpose inverter or motor).

  In addition, although stray capacitance is formed in various places in the evaluation device, the place that becomes the main conduction path of the high-frequency leakage current is formed between the midpoint of the three switching arms forming the inverter of FIG. 9 and the ground. Stray capacitance. Also, a cable connected to the midpoint of the 3 switching arm, a stray capacitance formed between the motor and the ground, and a stray capacitance between the midpoint of the arm and the ground, a cable connected to the midpoint of the 3 switching arm, Since the stray capacitance formed between the motor and the ground is also connected in parallel with the stray capacitance between the arm midpoint and the ground, it becomes a main high-frequency leakage current path.

  That is, the stray capacitance formed between the region 9 surrounded by the dotted line in FIG. 9 and the ground becomes the main path of the high-frequency leakage current (specifically, between the midpoint of the three switching arms of the IGBT module and the ground (three locations)). The stray capacitance formed between the cable (RST phase) and the ground, and between the motor winding and the ground), and the stray capacitance formed at other locations, but the high-frequency potential fluctuation is not applied. It is said that it does not become a proper leakage current path.

In addition, although the conduction noise has been described above, since radiation noise is generated by the conduction noise flowing, countermeasures against the conduction noise correspond to countermeasures against the radiation noise.
As a method for effectively reducing the high-frequency leakage current, conventionally, a three-phase collective short circuit is connected to the middle point of the switching arm to short-circuit the three phases of the inverter output, and this short-circuit point is used as a potential fixing circuit. A method is known in which the potential fluctuation at the neutral point is fixed at a low level by fixing the noise to reduce noise (for example, see Patent Document 1).

Also known is a method of suppressing noise current by inserting damping impedance between the motor frame and the ground line, between the cooling fin of the power converter and the ground line, and between the AC reactor and the ground line. (For example, refer to Patent Document 2).
Furthermore, a method of suppressing noise by interposing a common mode transformer at the next stage of the power supply and setting the resonance frequency of the secondary winding and the capacitor to the frequency band of the common mode component is also known (for example, (See Patent Document 3).

Furthermore, it is also known to suppress a noise peak by connecting a common mode choke that is a reactor to each phase of the midpoint of the inverter (for example, see Non-Patent Document 1).
JP 2004-222421 A JP 2006-25467 A JP 2006-136058 A "Modeling and Theoretical Analysis of High Frequency Leakage Current Generated by Voltage-Type PWM Inverter" Ogasawara, Fujita, Akagi, Denki Theory D, Vol. 115, No. 1, pp. 77-83, 1995

As disclosed in the above-mentioned document, the measure for reducing the noise of the common mode component mainly focuses on the stray capacitance between the midpoint of the switching arm and the ground line, and reduces the high-frequency leakage current flowing through it. It is something to be suppressed.
Here, the stray capacitance that is the main path of the high-frequency leakage current so far is mainly the stray capacitance between the midpoint of the switching arm and the ground line as described above (the cable and ground line in parallel with this stray capacitance). And the stray capacitance between the winding of the three-phase motor and the ground line). This stray capacitance has been the main path of high-frequency leakage current. Although there are stray capacitances at other locations, high-frequency potential fluctuations are not applied, and therefore, it is not considered as a main leakage current path.

  For this reason, in the above conventional example, in order to suppress the high-frequency leakage current flowing in the stray capacitance between the midpoint of each switching arm constituting the power conversion device and the ground line, an output short circuit is provided on the output side of the inverter. A potential fixing circuit that fixes the potential of the output short circuit is connected to suppress potential fluctuation at the neutral point of the motor (Patent Document 1), or between the motor frame, the cooling fin of the power converter, the AC reactor, and the ground (Patent Document 2), or the resonance frequency of the LC parallel resonance circuit formed by the secondary winding of the common mode transformer and the capacitor interposed between the power source and the converter is set to the common mode noise. (Patent Document 3), or an induction motor via a common mode choke and LC filter on the output side of the inverter Continued, and the neutral point of the filter capacitor of the LC filter, and or connected to the DC side of the inverter (N side) via a capacitor (Non-Patent Document 1).

  However, in each of the above conventional examples, as described above, attention is paid to the fact that the main path of the leakage current is the high-frequency leakage current flowing in the stray capacitance between the midpoint of the switching arm and the ground line. Although effective when the converter has a circuit configuration in which a high-frequency leakage current flows through the stray capacitance between the midpoint of each switching arm and the ground line as shown in FIG. 9, the main leakage current path is effective. However, unlike the above, there is an unsolved problem that it cannot be applied when a stray capacitance other than the stray capacitance between the midpoint and the ground line becomes a main leakage current path in a specific switching arm.

  In particular, for example, an uninterruptible power supply (UPS) having a mode in which a DC voltage is supplied from a power storage device such as a battery in order to secure the voltages across the switching arms (voltage between P and N) in the general-purpose inverter of FIG. There is a power conversion system. In this power conversion system, since the battery voltage and the PN voltage are generally different (the PN voltage is higher), the second voltage conversion function is provided between the battery and the general-purpose inverter. A power converter is added.

When the power conversion system is configured in this way, not only the stray capacitance between the control circuit and the ground, but also the stray capacitance between the second power conversion device and the ground, and further the stray capacitance between the battery and the ground is a source of conduction noise. Therefore, there is an unsolved problem that noise is greatly increased.
Therefore, the present invention has been made paying attention to the unsolved problems of the above conventional example, and the power from the power storage device is supplied to both ends of the first power conversion device and the switching arm of the first power conversion device. In the case of having the second power conversion device to be converted and supplied, the stray capacitance between the midpoint of the switching arm and the ground line does not become the main path of the high-frequency leakage current, and the midpoint and the ground line are not used in a specific switching arm. It is an object of the present invention to provide a power conversion system with low noise by reducing stray capacitance when stray capacitance other than stray capacitance becomes a main leakage current path.

In order to achieve the above object, a power conversion system according to claim 1 of the present invention provides a first power in which switching arms in which two or more switching elements are connected in series with one or more switching elements as one arm are connected in parallel in a plurality of rows. A power conversion system comprising: a conversion device; and a second power conversion device that converts power from a power storage device and supplies the power to both ends of the switching arm, wherein the first power conversion device, the second power conversion device The power converter and the power storage device are housed in a metal casing that prevents radiation noise from being emitted to the outside , and the metal casing is a printed circuit board on which the first power converter and the second power converter are mounted. as characterized by forming an insulating material to reduce the stray capacitance substrate housing area for accommodating and a partition portion leakage current path separating the power storage device housing area that houses the electrical storage device That.

  In the invention according to claim 1, the first power conversion device and the second power conversion device are accommodated by housing the printed circuit board on which the first power conversion device and the second power conversion device are mounted and the power storage device in the metal casing. This prevents the radiation noise generated by the power converter from being radiated to the outside, and the partition between the printed circuit board and the power storage device is made of an insulating material, reducing the stray capacitance that becomes the leakage current path. Reduce conduction noise.

A power conversion system according to claim 2 of the present invention includes: a first power conversion device in which two or more switching elements are connected in series with one or more switching elements as one arm; A power conversion system comprising: a second power conversion device that converts power into power at both ends of the switching arm;
The first power conversion device, the second power conversion device, and the power storage device are housed in a metal casing that prevents radiation noise from being radiated to the outside, and are insulative members at positions facing the internal electrodes of the power storage device. the arranged, to reduce the electrode area of the parallel plate capacitor formed between the internal electrode and the metal housing of the electric storage device, it is characterized in that a reduced stray capacitance becomes leakage current path.

In the invention according to claim 2, since the insulating member is disposed at a position facing the internal electrode of the power storage device, the parallel plate capacitor using the internal electrode of the battery and the metal casing as an electrode is provided by the insulating member. When formed, the opposing electrode area can be reduced by the insulating member, the stray capacitance can be reduced, and the conduction noise can be reduced.
According to a third aspect of the present invention, there is provided a power conversion system including: a first power conversion device in which two or more switching elements are connected in series with one or more switching elements as one arm; A power conversion system having a second power conversion device that converts power into power at both ends of the switching arm, and includes a printed circuit board on which the first power conversion device and the second power conversion device are mounted. The metal box is stored in a shielding metal box that prevents radiation noise from being emitted to the outside , and the metal box and the power storage device are stored in a casing formed of an insulating material. The stray capacitance that is the main path of the high-frequency leakage current is determined .

  In the invention according to claim 3, the printed circuit board on which the first power conversion device and the second power conversion device are mounted is housed in a metal box, and the metal box and the power storage device are formed in an insulating material. By storing it, the printed circuit board on which the switching element that is the source of radiation noise is mounted is shielded by a metal box to prevent radiation noise from radiating to the outside. Between the device and one surface of the metal box, the stray capacitance between the battery and the ground, which is the main path of high-frequency leakage current, is determined, and the conduction noise can be greatly reduced.

  According to the present invention, the power conversion system including the second power conversion device that converts the power from the first power conversion device and the power storage device and supplies the power to the switching arm of the first power conversion device is configured. When the first power conversion device and the second power conversion device are mounted, the stray capacitance between the printed circuit board and the power storage device, the stray capacitance between the power storage device and the metal housing, etc. are reduced to reduce conduction noise. The effect that it can be reduced is obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings referred to in the following description, the same parts as those in the other drawings are denoted by the same reference numerals.
(First embodiment)
FIG. 1 is a circuit diagram illustrating a single-phase PWM (Pulse Width Modulation) converter as a power conversion device illustrating the principle of the present invention. The case where the stray capacitance between the midpoint of the switching arm and the ground line found by the present inventor is not the main path of the high-frequency leakage current will be described using this circuit diagram. First, the circuit of FIG. 1 will be described.

  In FIG. 1, single-phase AC power output from a single-phase AC power supply 10 is supplied to a pseudo power supply network (hereinafter referred to as LISN) 11 for impedance matching. The R phase on the output side of this LISN 11 is connected to a first power converter 13 composed of a single-phase PWM converter via a normal reactor 12, and the S phase is directly connected to the first power converter 13. Yes.

The first power converter 13 has two rows of switching arms SA1 and SA2, and the R-phase line and S-phase line of LISN 11 are connected to the midpoints of the switching arms SA1 and SA2 of each row, respectively.
The switching arm SA1 is composed of switching elements S1 and S2 composed of, for example, IGBTs (Insulated Gate Bipolar Transistors) connected in series, and diodes D1 and D2 individually connected in reverse parallel to the switching elements S1 and S2. Has been.

Similarly, the switching arm SA2 is composed of switching elements S3 and S4 made of, for example, IGBTs connected in series, and diodes D3 and D4 individually connected in antiparallel to the switching elements S3 and S4. Yes. The switching element of each switching arm SA1 and SA2 and the diode parallel circuit constitute one arm.
The R phase of the LISN 11 is connected to the midpoint of the switching elements S1 and S2 of the switching arm SA1 via the normal reactor 12, and the midpoint of the switching elements S3 and S4 of the switching arm SA2 is connected to the S phase of the LISN 11. Yes. The collectors of the switching elements S1 and S3 of the switching arms SA1 and SA2 are connected to the positive line P, and the emitters of the switching elements S2 and S4 of the switching arms SA1 and SA2 are connected to the negative line N. A smoothing capacitor Cdc is connected between the positive electrode line P and the negative electrode line N on the output side.

  In the first power conversion device 13, the switching elements S1, S2 and S3, S4 of the same switching arm SA1 and SA2 according to the AC power inputted to the switching elements S1 to S4 constituting the switching arms SA1 and SA2. DC power is output to the positive line P and the negative line N by performing on / off control by PWM control so that the two are not simultaneously turned on. In this circuit, power conversion can also be performed for power regeneration from the load side to the power source side of the first power conversion device 13.

  In the circuit shown in FIG. 1, a main path of high-frequency leakage current based on high-speed switching will be described. The high-frequency leakage current that flows through the stray capacitance due to the switching in the switching arms SA1 and SA2 is caused by the potential fluctuation at the midpoint of the switching arm due to this switching. Therefore, if this potential fluctuation can be suppressed, the high-frequency leakage current for charging and discharging the stray capacitance can be reduced. Here, the switching of the switching arm SA1 connected to the R-phase line and the switching of the switching arm SA2 connected to the S-phase line are different depending on the presence or absence of the normal reactor 12 in terms of the circuit configuration. And the potential fluctuation at the midpoint of SA2 is different.

(Switching of switching arm connected to R phase line)
The high-frequency leakage current generated by switching of the switching element S1 or S2 flows through the stray capacitance Cs2 between the midpoint of the switching arm SA1 and the ground line. That is, the potential of the ground line is a neutral point potential of the R-phase potential and the S-phase potential due to the circuit configuration inside the LISN 11, and therefore, even if a high-frequency potential fluctuation due to switching occurs in the R-phase potential and the S-phase potential It is not a thing. Moreover, even if a high-frequency potential fluctuation occurs due to switching in the R phase, the voltage sharing is performed between the normal reactor 12 and the stray capacitance Cs2 for this potential fluctuation. Therefore, the shared potential fluctuation charges / discharges only the stray capacitance Cs2 and flows through the ground line as a high-frequency leakage current. In this respect, the stray capacitance between the midpoint of the switching arm and the ground line becomes the main path of the high-frequency leakage current as in the case of FIG.
(Switching of switching arm connected to S phase line)
The high-frequency leakage current generated by switching of the switching elements S3 and S4 is as follows. As described above, the potential of the ground line is a neutral point potential of the R-phase potential and the S-phase potential due to the circuit configuration inside the LISN 11, and therefore even if a high-frequency potential fluctuation due to switching occurs in the R-phase potential and the S-phase potential. Not big. That is, the midpoint potential of the switching arm SA2 composed of the switching elements S3 and S4 is an S-phase potential that is a stable potential, and a large potential fluctuation does not occur and a large high-frequency leakage current does not occur in the stray capacitance Cs4.

However, when the entire block including the switching arm SA2 including the switching elements S3 and S4 and the positive line P and the negative line N is viewed, a large potential fluctuation occurs. In this case, the potential fluctuation between the positive electrode line P and the negative electrode line N corresponds to the DC intermediate voltage Vcdc that is the voltage across the terminals of the smoothing capacitor Cdc. That is, the following operation is performed.
<When S3 is on and S4 is off>
The potential fluctuation of the positive line P is the S phase potential, and the potential fluctuation of the N line is S phase potential−DC intermediate voltage Vcdc.

<When S3 is off and S4 is on>
The potential variation of the positive line P is S phase potential + DC intermediate voltage Vcdc, and the potential variation of the negative line N is S phase potential.
Accordingly, the potential at the midpoint of the switching arm SA2 becomes the potential of the positive line P or the negative line N depending on the switching state, and the potential fluctuation becomes the DC intermediate voltage Vcdc.

  As a result, when the switching arm SA1 of the switching elements S1 and S2 is switched, the high-frequency leakage current based on the high-frequency potential fluctuation flows through the stray capacitance Cs2 as the main circuit as described above, whereas the switching elements S3 and S4 When the switching arm SA2 is switched, the high-frequency potential fluctuation spreads to the positive line P and the negative line N, and other than the stray capacitance Cs4, for example, stray capacitances Cs1, Cs3 between the collectors of the switching elements S1, S3 and the ground line, A high-frequency leakage current having a stray capacitance between all the switching elements and the ground line E as a main path flows (here, the midpoint potential of the switching arm SA1 composed of the switching elements S1 and S2 is always the positive line P or the negative line) Since this is connected to N, this midpoint and ground Stray capacitance Cs2 generated between the in-E also becomes a high-frequency leakage current path).

Therefore, even when the stray capacitance between the midpoint of the switching arm SA2 and the ground line does not become the main path of the high-frequency leakage current, the main path of the high-frequency leakage current is formed by another stray capacitance, and this other stray capacitance The largest high-frequency leakage current flows through this.
Further, the negative electrode line N in FIG. 1 is generally often equal to the reference potential of the control circuit. At this time, the stray capacitance between the wiring of the control circuit and the ground line E also becomes the main path of the high-frequency leakage current, and many circuit configurations and print patterns are affected by the common mode component.

  FIG. 2 illustrates the converter and inverter of the single-phase uninterruptible power supply device taken out. In FIG. 2, (a), (b), and (c) show examples in which the installation positions of the reactors L1 to L3 serving as filters are different. As can be seen from the example of FIG. 1, in FIG. 1, a normal reactor is interposed not only in the R-phase line but also in the S-phase line, so that a countermeasure for preventing high-frequency leakage current due to other stray capacitance is generally considered. is there. However, as a practical problem, installing a plurality of large normal reactors increases the bulk of the power conversion device and goes against the downsizing of the device. Therefore, if the number of reactors is reduced as much as possible, the problem that the main path of the high-frequency leakage current is formed by other stray capacitance as described above becomes obvious. In this respect, the illustration of FIG. 2 is the same, and FIGS. 2A to 2C are those in which at least one switching arm does not connect a reactor (that is, an impedance element) and becomes a switching arm having a relatively low impedance. is there.

  2A to 2C, a LISN 21 is connected to the single-phase power source 20, and the R-phase line of the LISN 21 is connected to a converter 22 as a first power converter. The converter 22 includes a switching arm SA1 including switching elements S1 and S2 and diodes D1 and D2 connected in reverse parallel thereto, and a switching arm including switching elements S5 and S6 and diodes D5 and D6 connected in reverse parallel thereto. SA3 has a structure composed of two rows of switching arms connected in series up and down around the midpoint. The R-phase line and the S-phase line are connected to the midpoint of the switching arms SA1 and SA2. Further, a smoothing capacitor Cdc is provided in the converter 22.

  An inverter 23 is arranged at the next stage of the converter 22. In this inverter 23, a switching arm SA3 in which two arms, each of which is composed of switching elements S5 and S6 and diodes D5 and D6 connected in antiparallel with each other, are connected in series up and down around the middle point is shared with the converter 22. In parallel with the switching arm SA3, a switching arm SA4 in which switching elements S7 and S8 and two arms connected in antiparallel with the diodes D7 and D8 are connected in series up and down around the middle point is connected. Has been. That is, the inverter 23 has two rows of switching arms SA3 and SA4, and each switching arm SA3 and SA4 has switching elements S5, S6 and S7, S8 and diodes D5, D6 and D7 connected in reverse parallel thereto. Two arms consisting of D8 are connected in series up and down around the midpoint. Here, the midpoint of the switching arm SA4 on the output side of the inverter 23 is connected to the load 24. Further, this circuit is provided with capacitors C1 and C2 serving as filters between the R phase and the S phase on the input side of the converter 22 and the output side of the inverter 23, respectively.

Further, in FIG. 2A, reactors L1 and L3 are provided at the midpoint of the input side switching arm SA1 of the converter 22 and the midpoint of the output side switching arm SA4 of the inverter 23, respectively. The midpoint of the shared switching arm SA3 is directly connected to the S phase line.
2B, the midpoint of the common switching arm SA3 and the S-phase line are connected via a reactor L2, and the reactor L3 is provided at the midpoint of the output side switching arm SA4 of the inverter 23.

Further, in FIG. 2C, a reactor L1 is provided at the midpoint of the input side switching arm SA1 of the converter 22, and the midpoint of the common switching arm SA3 and the S-phase line are connected via the reactor L2. .
Accordingly, each of the circuits shown in FIGS. 2A to 2C has a switching arm that is not connected to the reactor, that is, a switching arm that has a relatively small impedance. The midpoint of the switching arm to which the reactor, that is, the impedance element is not connected, is electrically similar to the midpoint of the switching arm SA2 of the switching elements S3 and S4 of the first power converter 13 shown in FIG. Become.

  That is, in FIG. 2A, the switching arm SA3 having the switching elements S5 and S6 is switched, in FIG. 2B, the switching arm SA1 having the switching elements S1 and S2 is switched, and in FIG. By switching the switching arm SA4 having the switching elements S7 and S8, the largest high-frequency leakage current flows so that the stray capacitance formed between the midpoint of each switching arm and the ground line E does not become the main path.

  As described above, the negative electrode line N in FIG. 1 is generally often equal to the reference potential of the control circuit. This is because the switching elements S2 and S4 of the lower arm in FIG. 1 can be driven without insulation by making the negative electrode line N the same as the reference potential of the control power supply. However, in this case, since all the stray capacitance between the control circuit unit (including the printed pattern, switching element, and passive element) and the ground is the main path of the high-frequency leakage current, the conduction noise is greatly increased.

Further, in the circuit configuration shown in FIG. 1 and FIG. 2, in order to secure the voltage across the switching arms SA1 to SA4 (voltage between PN), the first power converter 13 or the first power converter A configuration is known in which a power converter having a mode of supplying power from a power storage device such as a battery is connected in parallel with the converter 22.
A typical device is an uninterruptible power supply (UPS).

  Here, generally, the value of the storage voltage of a power storage device such as a battery and the voltage between the positive line P and the negative line N are different. That is, the voltage value between the positive line P and the negative line N is higher than the output voltage value of a power storage device such as a battery. Therefore, a second power conversion device having a transformation function is added between the power storage device such as a battery and the first power conversion device 13 in FIGS. 1 and 2.

That is, as shown in FIG. 3, the second power conversion device 40 connected to the power storage device 39 such as a battery is connected in parallel to the output side of the first power conversion device 13.
This second power conversion device 40 includes a capacitor 41 charged by a power storage device 39 such as a battery, a transformer 42 that transmits the output of the power storage device 39 to the secondary side, a transistor connected in series to the transformer 42, and It includes a switching element S composed of a diode D connected in reverse parallel thereto, a rectifier diode 43 connected to the secondary side of the transformer 42, and a smoothing capacitor 44. Then, both ends of the smoothing capacitor 44 are connected to the positive line P and the negative line N on the output side of the first power converter 13.

  Moreover, you may comprise a 2nd power converter device as shown in FIG. The second power conversion device 40 in this case includes a capacitor 41 charged by a power storage device 39 such as a battery, switching elements Sa, Sb, Sc, and Sd, and diodes Da, Db, Dc connected in reverse parallel to them. A transistor bridge TB constituted by Dd, a connection point of the switching elements Sa and Sb, a transformer 42 connected to the connection point of the switching elements Sc and Sd, and a diode bridge 45 connected to the secondary side of the transformer 42 Then, both ends of the diode bridge 45 are connected to the positive line P and the negative line N on the output side of the first power converter 13 in FIG.

Here, the second power converter 40 shown in FIGS. 3 and 4 also includes a switching element. At this time, the negative electrode line N ′ in FIGS. 3 and 4 and the negative electrode line N connected to the first power converter (FIGS. 1 and 2) may have the same potential via the control circuit. Many.
This is because the transformer 42 included in the second power conversion device 40 of FIGS. 3 and 4 is not intended for insulation but for transformation, and is not insulated from the control circuit. This is because the control circuit can be simplified and the cost can be reduced if the switching element is connected by driving the switching element.

However, in such a configuration, not only the stray capacitance between the control circuit and the ground described above but also the stray capacitance between the second power conversion device 40 and the ground is a high-frequency leakage that becomes a conduction noise source. There is a concern that noise will increase significantly due to the current path.
In order to solve this, in the circuit configuration of FIG. 3 described above, the first power converter 13 and the second power converter 40 described above are mounted on the printed circuit board 50 as shown in FIG. The printed circuit board 50 is stored in a board storage area 50 a formed on the upper side in the metal casing 51, and the power storage device 39 is stored in a power storage apparatus storage area 50 b formed on the lower side in the metal casing 51. A partition 52 formed of an insulating material such as plastic is provided between the board storage area 50 a that stores the printed circuit board 50 and the power storage apparatus storage area 50 b that stores the power storage apparatus 39. Here, in the partition unit 52, the interval between the partition unit 52 and the power storage device 39 is set to be relatively wide so that the printed circuit board 50 portion does not come into contact with the power storage device 39.

  As described above, by providing the partition portion 52 formed of an insulating material between the printed circuit board 50 and the power storage device 39, the stray capacitance generated between the power storage device 39 and the metal casing 51 serving as the ground is reduced. The conduction noise can be reduced by reducing the stray capacitance that becomes the path of the high-frequency leakage current. At this time, the entire device including the printed circuit board 50 and the power storage device 39 on which the first power conversion device 13 and the second power conversion device 40 are mounted is housed in the metal casing 51 to shield radiation noise. An increase in radiation noise radiated to the outside of the apparatus can be prevented.

  Incidentally, conventionally, the partition 52 is provided so as not to come into contact with the printed circuit board 50 when the power storage device 39 is replaced, and is made of a metal material in the same manner as the metal housing 51 in order to prevent radiation noise weight to the battery power supply line. It is often configured and electrically connected to the metal casing 51. As a result, the power storage device 39 is surrounded by the adjacent metallic partition, and the stray capacitance between the power storage device 39 and the housing 51, which is the main leakage current path, is increased as described above. Cause noise to increase. However, in the present embodiment, the partition 52 formed of an insulating material is provided between the printed circuit board 50 and the power storage device 39, thereby reducing the stray capacitance between the power storage device 39 and the metal casing 51. can do.

Next, a second embodiment of the present invention will be described with reference to FIG.
In the second embodiment, the stray capacitance between the surface of the power storage device 39 other than the surface facing the printed board 50 and the housing is reduced.
That is, in the second embodiment, as shown in FIG. 6, an insulating member 60 made of an insulating material such as plastic is disposed at least on the surface facing the internal electrode plate 39 a of the power storage device 39. Here, the insulating member 60 is formed in a U-shaped cross section from left and right end portions 60 a and 60 b facing the internal electrode plate 39 a of the power storage device 39 and a connecting plate portion 60 c that connects them on the upper side of the power storage device 39. The left end 60 a is configured as a part of the metal casing 51, and the right end 60 b is interposed between the power storage device 39 and the metal casing 51.

  In this way, the power storage device 39 is covered with the insulating member 60 in consideration of the internal structure thereof, and the stray capacitance is reduced by focusing on the location where the stray capacitance is formed most greatly with the power storage device 39. Stray capacitance between the ground and the ground can be reduced. That is, when the power storage device 39 is constituted by a lead storage battery, as shown in FIG. 7, a plurality of, for example, six cells 66a to 66f are formed in the battery case 65, and the leftmost cell 66a is constituted by lead dioxide. The plus electrode 67 is arranged, and the minus electrode 68 made of lead is arranged in the rightmost cell 66f. A separator 69 and a glass mat 70 are disposed in each of the cells 66a to 66f. Between the cells adjacent to each of the cells 66a to 66f, a negative electrode 71n and a positive electrode 71p for connecting them in series are disposed, and the cells 66a to 66f are connected in series by the negative electrode 71n and the positive electrode 71p. . Since each cell 66a-66f outputs several V (for example, 2V), 12V can be output by six cells 66a-66f.

  By the way, each cell 66a-66f has a total of 12 electrodes, negative electrode 71n and positive electrode 71p, plus electrode 67, and minus electrode 68 for connecting cells in series, and these include lead and lead dioxide. Composed of metal. Since each electrode connects the cells 66a to 66f in series, a positive electrode 67 and a negative electrode 68 connected to an external output, and a negative electrode 71n and a positive electrode 71p between the cells are connected and supported in series. A total of seven metal bodies are present inside the power storage device 39 with five sets of insulating partition plates 72 that can be connected. These form a stray capacitance with the housing.

Depending on the circuit system for boosting the battery voltage to the PN voltage and the specification of the power supply time by the power storage device 39, a plurality of power storage devices 39 may be connected in series. In this case, the stray capacitance is further increased. Become.
Here, the capacitance of the parallel plate capacitor is proportional to the electrode area and inversely proportional to the distance between the electrodes. Since the stray capacitance between the power storage device 39 and the housing 51 can be regarded as a parallel plate capacitor using the electrode of the power storage device 39 and the housing 51 as an electrode, the stray capacitance can be reduced by reducing the opposing electrode area. Can be reduced.

Therefore, by setting a part of the casing 51 at a position facing the internal electrode of the power storage device 39 as the left end portion 60a of the insulating member 60, the stray capacitance between the power storage device 39 and the ground can be reduced, and noise can be reduced. A small uninterruptible power supply can be realized.
In the second embodiment, the case where only the left end portion 60a of the insulating member 60 is configured as a part of the metal casing 51 has been described. However, the present invention is not limited to this, and the right end portion 60b is also made of metal. It can also be configured as a part of the casing 51.

Next, a third embodiment of the present invention will be described with reference to FIG.
In the third embodiment, in the second embodiment described above, the insulating member 60a is disposed at a position facing the internal electrode of the power storage device 39 of the metal casing 51, whereby the internal electrode of the power storage device 39 is arranged. The case where the stray capacitance between the ground and the ground is reduced has been described. In this case, by forming a part of the metal casing 51 with the insulating member 60a, the shielding effect of the radiation noise is reduced, and the radiation noise is reduced. Although this may increase, it is intended to suppress this.

  That is, in the third embodiment, as shown in FIG. 8, the first power conversion device is used for the purpose of preventing leakage of radiation noise outside the device while reducing the stray capacitance between the power storage device 39 and the ground. 13 and the second power converter 40 are mounted in a metal box 80, and the metal box 80 and the power storage device 39 are stored in an insulating casing 81 made of an insulating material such as plastic. It is configured. Here, since the metal box 80 is used for the purpose of shielding the printed circuit board 50 on which a switching element or the like serving as a radiation noise source is mounted, it does not matter whether it is connected to the ground potential.

  According to the third embodiment, the stray capacitance between the power storage device 39, which is the main path of the high-frequency leakage current, and the ground is configured such that the entire insulating housing 81 is made of an insulating material such as plastic. Therefore, the conduction noise can be greatly reduced. By adopting such a configuration, an uninterruptible power supply device with small conduction noise and radiation noise can be realized.

  The present invention can be used for countermeasures such as conduction noise and radiation noise generated by the first and second power conversion devices and the power storage device.

It is a circuit diagram showing a schematic structure of a converter for explaining an embodiment of the present invention. It is a circuit diagram showing a schematic structure of a power converter as a 1st embodiment of the present invention. It is a circuit diagram which shows the uninterruptible power supply which can apply this invention. It is a circuit diagram which shows the other example of the 2nd power converter device. It is a typical perspective view which shows the housing structure of the 1st Embodiment of this invention. It is a typical perspective view which shows the housing structure of the 2nd Embodiment of this invention. It is sectional drawing which shows an example of the electrical storage apparatus which can be applied to this invention. It is a typical perspective view which shows the housing structure of the 3rd Embodiment of this invention. It is a circuit diagram which shows the power converter device of a prior art example. It is a common mode equivalent circuit diagram showing the high frequency leakage current simply.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Three-phase power supply, 2 ... Pseudo power supply network, 3 ... Diode rectifier, 4 ... Smoothing capacitor, 5 ... General-purpose inverter, 6 ... Cable, 7 ... Three-phase motor, 8 ... Spectrum analyzer, 10 ... AC power supply, 12 ... Normal reactor, 13 ... first power conversion device, 20 ... single phase power supply, 22 ... converter, 23 ... inverter, 24 ... load, 39 ... power storage device, 40 ... second power conversion device, 41 ... capacitor, 42 ... Transformer 43 ... rectifier diode 44 ... smoothing capacitor 45 ... diode bridge 50 ... printed circuit board 51 ... metal housing 52 ... partitioning part 60 ... insulating member 60a ... left end 60b ... right end 60c ... Connection end part 65 ... Battery case 66a-66f ... Cell, 67 ... Positive electrode, 68 ... Negative electrode, 71n ... Negative electrode, 71p ... Positive electrode, 72 ... Insulation partition plate, 0 ... metal box, 81: insulating housing, L ... inductance, L1 to L3 ... reactors, S, S1 to S8, Sa to Sd ... switching device, SA1 to SA4 ... switching arms

Claims (3)

A first power conversion device in which two or more switching elements are connected in series with one or more switching elements as one arm, and power from the power storage device is converted and supplied to both ends of the switching arm. A power conversion system comprising: a second power conversion device that includes:
The first power conversion device, the second power conversion device, and the power storage device are housed in a metal casing that prevents radiation noise from being emitted to the outside , and the metal casing includes the first power conversion device and the first power conversion device. The partition part which partitions the board | substrate storage area | region which accommodates the printed circuit board which mounts a 2nd power converter device, and the electrical storage apparatus accommodation area | region which accommodates the said electrical storage apparatus was formed with the insulating material which reduces the stray capacity used as a leakage current path | route. Power conversion system characterized by A first power conversion device in which two or more switching elements are connected in series with one or more switching elements as one arm, and power from the power storage device is converted and supplied to both ends of the switching arm. A power conversion system comprising: a second power conversion device that includes:
The first power conversion device, the second power conversion device, and the power storage device are housed in a metal casing that prevents radiation noise from being radiated to the outside, and are insulative members at positions facing the internal electrodes of the power storage device. To reduce the stray capacitance that becomes a leakage current path by reducing the electrode area of the parallel plate capacitor formed between the internal electrode of the power storage device and the metal casing. system. A first power conversion device in which two or more switching elements are connected in series with one or more switching elements as one arm, and power from the power storage device is converted and supplied to both ends of the switching arm. A power conversion system comprising: a second power conversion device that includes:
A printed circuit board on which the first power conversion device and the second power conversion device are mounted is housed in a shield metal box that prevents radiation noise from being emitted to the outside , and the metal box and the power storage device are insulated from each other. The power conversion system is characterized in that the stray capacitance, which is housed in the housing formed in step (1), is determined as a main path of high-frequency leakage current between one surface of the metal box and the power storage device .

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