JP2009089542A - Smoothing capacitor arranging structure for dc chopper device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a smoothing capacitor mounting structure for DC chopper device, which allows a capacitor of capacity effective for smoothing to be built in without incurring increase of elements or occurrence of wiring. <P>SOLUTION: A smoothing capacitor 7 is mounted together with a switching power module 13 on a main circuit board 11 and they are built in a casing 15. Hereby, as compared with the DC chopper device where the smoothing capacitor is attached outside to the casing 15, the wiring length between the switching power module 13 and the smoothing capacitor 7 is shortened, and wiring impedance is made extremely small. As a result, it can reconcile actually the downsizing of the smoothing capacitor 7 and the building in the casing 15 by enabling the smoothing capacitor 7 to be used efficiently. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a DC chopper device that converts a DC input into a DC output having a different voltage by a switching power device, and more particularly to an arrangement structure of a smoothing capacitor for smoothing the chopper input.

  The DC chopper device converts a DC input into a DC output having a different voltage by a switching power device. Similar to this DC chopper device, there is an inverter device that converts a DC input using a switching power device into an AC output using a switching power device.

In this inverter device, a large current ripple is generated on the inverter input side due to voltage fluctuation accompanying switching of the switching power device. For this reason, in order to reduce the burden on DC power sources such as batteries and to extend the life thereof, conventionally, a large-capacity smoothing capacitor with a large volume is externally attached to the casing of the inverter device to smooth the inverter input. (For example, Patent Document 1).
Japanese Patent Laid-Open No. 2000-152626

  If the external smoothing capacitor and the switching power device in the housing are connected to the housing by wiring, the wiring is connected by connecting the inside and outside of the housing, so that the wiring distance becomes long and the wiring resistance increases. This increases the wiring impedance. In particular, when the switching power device is switched at high speed, the wiring inductance increases in proportion to the switching frequency, so that the wiring impedance becomes considerably high, which causes a further increase in the wiring impedance.

  As described above, when the wiring impedance of the smoothing capacitor is high, it is difficult to take in and out charges to the smoothing capacitor, the smoothing efficiency is lowered, and the inverter input cannot be sufficiently smoothed. Then, as described above, the burden on the DC power supply is increased, which not only adversely affects the life of the DC power supply, but also has an adverse effect that a large current ripple occurs in the inverter output and the loss in the load increases.

  Further, as the current ripple at the inverter output increases, the level of surge voltage accompanying switching of the switching power device also increases, which may cause damage to the switching power device.

  In some cases, a snubber circuit having a capacitor is provided in the casing of the inverter device for suppressing the surge voltage. However, the capacitor of the snubber circuit is insufficient in capacity for smoothing the inverter input, and an external smoothing capacitor cannot be made useless.

  It is also conceivable to reduce the capacity (volume) of the external smoothing capacitor by using it together with the snubber circuit. However, in reality, the capacitor of the snubber circuit that is closer to the switching power device than the smoothing capacitor on the circuit is the result of trying to participate in the smoothing of the inverter input more dominantly than the smoothing capacitor, despite the lack of capacity. The smoothing efficiency of the inverter input by the smoothing capacitor is lowered. For this reason, even if it is used in combination with a snubber circuit, the capacity (volume) of the smoothing capacitor cannot be reduced as expected.

  Therefore, when a snubber circuit composed of resistors, reactances (coils, capacitors), diodes, etc. is used, smoothing of the inverter input does not become space-saving and efficient, it simply increases the number of parts. It may end just to bring Rather, the snubber circuit capacitor may cause an abnormal heat generation of the snubber circuit by participating in the smoothing of the inverter input despite the insufficient capacity. Finding a smoothing function is not an ideal idea.

  And such a problem is common also in the direct current chopper device which performs conversion of direct current input using a switching power device like an inverter device.

  In view of the above circumstances, the present invention has been made by paying attention to the fact that a DC chopper device is expected to be used in an environment different from the electrical environment (conditions) used conventionally. An object of the present invention is to provide a smoothing capacitor arrangement structure of a direct current chopper device that can achieve both high-efficiency smoothing of chopper input and downsizing of the device.

  In order to achieve the above object, a smoothing capacitor arrangement structure of a DC chopper device according to the present invention as set forth in claim 1 is characterized in that a chopper input in a DC chopper device that converts a DC input into a DC output having a different voltage by a switching power device is provided. A smoothing capacitor arrangement structure for smoothing, wherein the smoothing capacitor is housed in a moisture-proof or heat radiating housing in which the switching power device is housed.

  According to the smoothing capacitor arrangement structure of the direct current chopper device according to the first aspect of the present invention, the smoothing capacitor is disposed in the same casing as the switching power device to which the wiring is connected. For this reason, the wiring distance between the smoothing capacitor and the switching power device is shorter than that of the DC chopper device in which the smoothing capacitor is externally attached to the housing as in the conventional inverter device.

  Therefore, the wiring impedance relating to the smoothing capacitor is reduced, and even if the switching power device performs switching at a high speed, the charging / discharging of the smoothing capacitor is not hindered, and the smoothing capacitor can be used efficiently. Therefore, the chopper input can be sufficiently smoothed even if the capacitance (volume) is reduced as compared with the case where the smoothing capacitor is externally attached to the housing.

  As a result, it is possible to reduce the size of the DC chopper device by smoothing the chopper input with high efficiency and realizing the built-in housing by reducing the capacity (volume) of the smoothing capacitor.

  According to a second aspect of the present invention, there is provided a smoothing capacitor arrangement structure for a DC chopper device according to the present invention, in which a smoothing capacitor for smoothing a chopper input in a DC chopper device that converts a DC input into a DC output having a different voltage by a switching power device. An arrangement structure is characterized in that the smoothing capacitor is mounted on a substrate on which the switching power device is mounted.

  According to the smoothing capacitor arrangement structure of the DC chopper device of the present invention described in claim 2, the smoothing capacitor is mounted on the same substrate as the switching power device to which the wiring is connected. For this reason, the wiring distance between the smoothing capacitor and the switching power device is shorter than that of the DC chopper device in which the smoothing capacitor is externally attached to the housing as in the conventional inverter device.

  Therefore, the wiring impedance relating to the smoothing capacitor is reduced, and even if the switching power device performs switching at a high speed, the charging / discharging of the smoothing capacitor is not hindered, and the smoothing capacitor can be used efficiently. Therefore, the chopper input can be sufficiently smoothed even if the capacitance (volume) is reduced as compared with the case where the smoothing capacitor is externally attached to the housing.

  As a result, it is possible to reduce the size of the DC chopper device by smoothing the chopper input with high efficiency and realizing the built-in housing by reducing the capacity (volume) of the smoothing capacitor.

According to a third aspect of the present invention, there is provided a smoothing capacitor arrangement structure for a DC chopper device according to the present invention. In the arrangement structure, the length L of the wiring that electrically connects the switching power device and the smoothing capacitor is:
L <50cm
Is,
It is characterized by that.

  According to the smoothing capacitor arrangement structure of the DC chopper device of the present invention described in claim 3, the length L of the wiring for electrically connecting the switching power device and the smoothing capacitor is within 50 cm. Is mounted in the same housing as the switching power device, or mounted on the same substrate as the switching power device or on another substrate arranged very close to the switching power device. For this reason, the wiring distance between the smoothing capacitor and the switching power device is shorter than that of the DC chopper device in which the smoothing capacitor is externally attached to the housing as in the conventional inverter device.

  Therefore, the wiring impedance relating to the smoothing capacitor is reduced, and even if the switching power device performs switching at a high speed, the charging / discharging of the smoothing capacitor is not hindered, and the smoothing capacitor can be used efficiently. Therefore, the chopper input can be sufficiently smoothed even if the capacitance (volume) is reduced as compared with the case where the smoothing capacitor is externally attached to the housing.

  As a result, it is possible to reduce the size of the DC chopper device by smoothing the chopper input with high efficiency and realizing the built-in housing by reducing the capacity (volume) of the smoothing capacitor.

  The smoothing capacitor arrangement structure of the DC chopper device of the present invention described in claim 4 is characterized in that the DC chopper device has a voltage of the DC input and the DC output of 100 volts or less and a current of the DC input and the DC output. Is a low-voltage, large-current specification having a current of 10 amperes or more.

  According to the smoothing capacitor arrangement structure of the DC chopper device of the present invention described in claim 4, since the DC input and DC output of the DC chopper device are large currents having a peak value of 10 amperes or more, the voltage fluctuation of the chopper input The current ripple of the chopper output due to is larger than in the case of low current.

  Therefore, the smoothing of the chopper input greatly contributes to the reduction of the loss and heat generation in the load, and also greatly contributes to the suppression of the surge voltage level accompanying the switching of the switching power device.

  As a result, smoothing of the chopper input with high efficiency and downsizing of the DC chopper device by realizing the housing built-in by reducing the capacity (volume) of the smoothing capacitor can be realized in a more remarkable form.

  According to the smoothing capacitor arrangement structure of the DC chopper device according to the present invention, the chopper input is smoothed with high efficiency, and the DC chopper device is miniaturized by realizing the built-in housing by reducing the capacity (volume) of the smoothing capacitor. can do.

  Hereinafter, a DC chopper device according to an embodiment of the present invention to which a smoothing capacitor arrangement structure according to the present invention is applied will be described.

  First, a DC chopper device according to this embodiment will be described with reference to an equivalent circuit diagram shown in FIG. The DC chopper device of this embodiment supplies a DC output obtained by boosting a DC input from a DC power supply 8 to a load 9 such as an inverter or a constant voltage circuit, and is an insulated gate bipolar as a switching power device. A transistor (Insulated Gate Bipolar Transistor, hereinafter abbreviated as “IGBT”) 1, a coil 3, a diode 5, and a smoothing capacitor 7. A flywheel diode 1a is provided between the collector and emitter of the IGBT1.

  In place of the IGBT, a MOSFET (metal oxide field effect transistor = unipolar transistor), a bipolar transistor, or the like can be used as a switching power device. The smoothing capacitor 7 can be a film capacitor, an electrolytic capacitor, a ceramic capacitor, or the like.

  The DC chopper device of this embodiment boosts the DC input from the DC power supply 8 and supplies the DC output to the load 9. Here, the DC chopper device of this embodiment handles DC input / output of a low voltage and large current of 100 volts or less and 10 amperes (peak value) or more.

  Next, the structure of the DC chopper device of the present embodiment having the above circuit configuration will be described with reference to the explanatory diagram of FIG.

  Reference numeral 13 in FIG. 2 is a switching power module obtained by modularizing the IGBT 1 and the flywheel diode 1 a described with reference to FIG. 1, and is mounted on the main circuit board 11. The main circuit board 11 corresponds to a “board on which a switching power device is mounted” in the claims. A smoothing capacitor 7 is mounted on the main circuit board 11 adjacent to the switching power module 13.

  As described above, the main circuit board 11 on which the switching power module 13 and the smoothing capacitor 7 are mounted adjacently is accommodated in the housing 15. The housing 15 is made of a material such as aluminum, copper, or stainless steel having excellent thermal conductivity so that heat generated by the switching power module 13 or the smoothing capacitor 7 can be easily released to the outside. Further, in order to prevent moisture from the main circuit board 11, the switching power module 13, and the smoothing capacitor 7, the surface of the housing 15 may be coated with rubber gel or the inside of the housing 15 may be filled with rubber gel or the like. is there.

  In the DC chopper device of the present embodiment housed in the casing 15 with such a configuration, the smoothing capacitor 7 and the switching power module 13 are electrically connected by a wiring pattern (not shown) on the main circuit board 11. The Therefore, the smoothing capacitor 7 and the switching power module are compared with the DC chopper device in which a smoothing capacitor is externally attached to the outside of the housing and electrically connected to the switching power module inside the housing, as in the conventional inverter device. The wiring distance to 13 is remarkably shortened.

  That is, for example, like the DC chopper device shown in FIG. 5 and FIG. 6, the upper portion of the housing 15 that houses a main circuit board (not shown) on which only a switching power module (not shown) is mounted. If the smoothing capacitor 7 </ b> A is disposed externally on the side, the switching power module (not shown) and the smoothing capacitor 7 </ b> A need to be electrically connected by the wiring 17 across the inside and outside of the housing 15.

  Further, as shown in the explanatory diagram of FIG. 7, a snubber circuit 19 composed of a resistor, a reactance (coil, capacitor), a diode, etc. (all not shown) is provided on the main circuit board 11 together with the switching power module 13. In the case of mounting, the capacity (volume) of the external smoothing capacitor 7A is slightly reduced by the amount of the capacitor (not shown) in the snubber circuit 19. However, it is still necessary to electrically connect the switching power module and the smoothing capacitor 7 </ b> A through the wiring 17 across the inside and outside of the housing 15.

  When the DC chopper device of FIGS. 5 to 7 with the smoothing capacitor 7A externally attached to the housing 15 is compared with the DC chopper device of the present embodiment shown in FIG. 2, the wiring between the smoothing capacitor and the switching power module is as follows. The difference in distance is obvious.

  Then, in order to externally attach the smoothing capacitor 7A to the housing 15 as in the DC chopper device of FIGS. 5 to 7, the smoothing capacitor 7A and the switching power module are compared with the DC chopper device of this embodiment shown in FIG. The equivalent circuit of the DC chopper device in which the wiring distance is significantly increased is as shown in the circuit diagram of FIG.

  5 to 8, the same elements and portions as those shown in FIGS. 1 and 2 are denoted by the same reference numerals as those shown in FIGS. Omitted.

  That is, in the DC chopper device of FIGS. 5 to 7, the reactance having a non-negligible magnitude on the discharge path to the load 9 of the smoothing capacitor 7A due to the long wiring distance between the smoothing capacitor 7A and the switching power module. Components (inductance L and resistance R) are generated.

  Accordingly, in the DC chopper device in which the smoothing capacitor 7A is externally attached to the housing 15 as shown in FIGS. 5 to 7, the wiring impedance in the wiring portion between the smoothing capacitor 7A and the switching power module is the DC chopper of this embodiment. It becomes much larger than the device. For this reason, the taking in and out of the electric charge to and from the smoothing capacitor 7A is greatly inhibited.

  In particular, when the IGBT 1 shown in FIG. 8 performs switching at high speed, the inductance component in the reactance component of the wiring 17 becomes very high according to the switching frequency. For this reason, the degree to which the impedance of the wiring 17 becomes very high and the charging / discharging of the electric charge to / from the smoothing capacitor 7A is inhibited becomes more remarkable.

  Accordingly, in the DC chopper device in which the smoothing capacitor 7A is externally attached to the housing 15 as shown in FIGS. 5 to 7, the capacity of the smoothing capacitor 7A cannot be fully utilized, and the capacity (volume) of the smoothing capacitor 7A is correspondingly reduced. A vicious cycle of having to increase the size of the DC chopper device is unavoidable.

  Further, if the smoothing capacitor 7A cannot sufficiently play a role in smoothing, as shown in the graph of FIG. 9, a large current ripple is generated also in the chopper output, and the loss in the load 9 to which the AC output of the DC chopper device is supplied. Adversely increases.

  Further, as the current ripple in the chopper output increases, as shown in the graph of FIG. 10, the surge voltage level accompanying the switching of the IGBT 1 also increases, which may cause damage to the IGBT 1. When a MOSFET (unipolar transistor) is used as a switching power device in place of the IGBT 1 shown in FIG. 8, the level of surge voltage appearing between the drain and source due to the switching is as shown in the graph of FIG. It increases as current ripple increases.

  On the other hand, if the smoothing capacitor 7 and the switching power module 13 are mounted on the main circuit board 11 and built in the housing 15 as in the DC chopper device of the present embodiment shown in FIG. The wiring distance between the capacitor 7 and the switching power module 13 is significantly shorter than the wiring 17 of the DC chopper device shown in FIGS.

  For this reason, as shown in the equivalent circuit diagram of FIG. 1, a reactance component (inductance and resistance) having a magnitude that cannot be ignored is not generated on the discharge path of the smoothing capacitor 7 to the load 9. For this reason, the charging / discharging of the smoothing capacitor 7 is not hindered.

  In particular, even if the IGBT 1 performs switching at a high speed, the impedance of the wiring that electrically connects the IGBT 1 and the smoothing capacitor 7 is extremely small, so that the inductance component of the wiring is slightly increased. Therefore, the taking in and out of the electric charge with respect to the smoothing capacitor 7 is not hindered.

  Therefore, the capacity of the smoothing capacitor 7 can be fully utilized efficiently, and the capacity (volume) of the smoothing capacitor 7 is made smaller than the smoothing capacitor 7A externally attached to the housing 15 as shown in FIGS. However, the chopper input can be sufficiently smoothed.

  As a result, the smoothing capacitor 7 can be mounted on the main circuit board 11 together with the switching power module 13 so as to be built in the housing 15, smoothing the chopper input with high efficiency, and supplying the smoothing capacitor 7 to the housing 1. A reduction in the size of the DC chopper device can be realized by realizing the built-in.

  When the smoothing capacitor 7 can sufficiently play a role in smoothing, the current ripple generated in the chopper output becomes small (or disappears) as shown in the graph of FIG. 3, so that the AC output of the DC chopper device is supplied. The loss in the load 9 can be suppressed (or eliminated).

  Further, as shown in the graph of FIG. 4, the surge voltage level accompanying the switching of the IGBT 1 is also lowered according to the suppression of the current ripple in the chopper output, so that the IGBT 1 is less likely to be damaged by the surge voltage. Reliability can be improved. When a MOSFET (unipolar transistor) is used as a switching power device in place of the IGBT 1 in FIG. 1, the level of the surge voltage appearing between the drain and the source is lowered as shown in the graph of FIG.

  In the present embodiment, the configuration in which the switching power module 13 and the smoothing capacitor 7 are accommodated in the casing 15 together with the main circuit board 11 has been described. However, the present invention also applies to a DC chopper device without the casing 15. Applicable.

  Further, in the case of the configuration in which the smoothing capacitor 7 is built in the housing 15, the smoothing capacitor 7 is not mounted on the same main circuit board 11 as the switching power module 13 as in the present embodiment. The present invention is applicable even when the smoothing capacitor 7 is mounted on this substrate.

  The wiring length L between the smoothing capacitor 7 and the switching power module 13 is assumed to satisfy L <50 cm through the present embodiment and the above-described modifications.

  By setting the wiring length L between the smoothing capacitor 7 and the switching power module 13 as described above, in the case of a DC chopper device having the housing 15, the smoothing capacitor 7 is practically built in the housing 15. It becomes the composition to do. In the case of a DC chopper device that does not have a housing 15, the smoothing capacitor 7 is mounted on the main circuit board 11 that is practically the same as the switching power module 13 or another board that is arranged close to the switching power module 13. It becomes composition.

  As a result, the wiring distance between the smoothing capacitor 7 and the switching power module 13 falls within such a length that the wiring impedance related to the wiring is negligible. Therefore, it is possible to efficiently and fully utilize the capacity of the smoothing capacitor 7 without greatly hindering the charge and withdrawal of the charge to and from the smoothing capacitor 7.

  Therefore, even if the capacity (volume) of the smoothing capacitor 7 is reduced to a size that allows the smoothing capacitor 7 to be incorporated in the housing 15, the smoothing capacitor 7 having a small capacity can sufficiently smooth the inverter input. While smoothing the chopper input with high efficiency, the DC chopper device can be miniaturized by realizing the built-in housing 15 by reducing the capacity (volume) of the smoothing capacitor 7.

  In addition, according to the DC chopper device of this embodiment and each of the modifications described above, since the DC output supplied to the load 9 is a large current having a peak value of 10 amperes or more, the chopper due to voltage fluctuation of the chopper input. The output current ripple has a larger volume than in the case of a low current.

  Therefore, the smoothing of the chopper input greatly contributes to the reduction of the loss and heat generation in the load 9 and also greatly contributes to suppressing the level of the surge voltage accompanying the switching of the IGBT 1.

  As a result, the smoothing of the chopper input with high efficiency and the downsizing of the DC chopper device by realizing the incorporation of the smoothing capacitor 7 in the housing 15 by reducing the capacity (volume) are realized in a more remarkable form. Can do.

It is an equivalent circuit diagram explaining the direct current chopper device concerning one embodiment of the present invention. It is explanatory drawing which shows the structure of the direct-current chopper apparatus which concerns on one Embodiment of this invention. It is a current waveform figure of the inverter output in the direct-current chopper device concerning one embodiment of the present invention. FIG. 2 is a waveform diagram of a surge voltage appearing between a collector and an emitter (drain and source) due to switching of each bipolar (unipolar) transistor of FIG. 1. It is explanatory drawing which shows the structural example of the DC chopper apparatus which attached the smoothing capacitor to the housing | casing externally. It is explanatory drawing which shows the structural example of the DC chopper apparatus which attached the smoothing capacitor to the housing | casing externally. It is explanatory drawing which shows the structural example of the DC chopper apparatus which attached the smoothing capacitor to the housing | casing externally. FIG. 3 is an equivalent circuit diagram of a DC chopper device in which a smoothing capacitor is externally attached to a housing. FIG. 6 is a current waveform diagram of an inverter output in a DC chopper device in which a smoothing capacitor is externally attached to a housing. FIG. 9 is a waveform diagram of a surge voltage that appears between a collector and an emitter (drain and source) due to switching of each bipolar (unipolar) transistor of FIG. 8.

Explanation of symbols

1 IGBT (switching power device)
7, 7A Smoothing capacitor 8 DC power supply 9 Load 11 Main circuit board 13 Switching power module 15 Case 17 Wiring

Claims (4)

In a DC chopper device that converts a DC input into a DC output having a different voltage by a switching power device, an arrangement structure of a smoothing capacitor for smoothing the chopper input,
The smoothing capacitor is housed in a moisture-proof or heat radiating housing in which the switching power device is housed.
A smoothing capacitor arrangement structure for a direct current chopper device. In a DC chopper device that converts a DC input into a DC output having a different voltage by a switching power device, an arrangement structure of a smoothing capacitor for smoothing the chopper input,
The smoothing capacitor is mounted on a substrate on which the switching power device is mounted.
A smoothing capacitor arrangement structure for a direct current chopper device. In a DC chopper device that converts a DC input into a DC output having a different voltage by a switching power device, an arrangement structure of a smoothing capacitor for smoothing the chopper input,
The length L of the wiring that electrically connects the switching power device and the smoothing capacitor is:
L <50cm
Is,
A smoothing capacitor arrangement structure for a direct current chopper device.   The DC chopper device has a low voltage and large current specification in which the voltage of the DC input and the DC output is 100 volts or less, and the current of the DC input and the DC output is 10 amps or more. The smoothing capacitor arrangement structure of the DC chopper device according to claim 1, 2, or 3.

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