阅读说明：本技术 电动机驱动装置 (Motor driving device ) 是由 松田凉 佐佐木拓 于 2020-10-15 设计创作，主要内容包括：本发明提供一种电动机驱动装置。可实现能够降低平滑电容器的热损失和缓冲电容器的热损失的、构造容易、小型且低成本的电动机驱动装置。电动机驱动装置包括：平滑电容器部,其具有至少一个平滑电容器,该平滑电容器设于生成电动机驱动电力的电力转换电路内的转换器电路与逆变器电路之间；缓冲电容器,其抑制构成电力转换电路的一部分的功率元件的浪涌电压；以及支承板,其供平滑电容器部设置,平滑电容器部的电极端子与缓冲电容器的电极端子隔着支承板接近地配置,平滑电容器部的正极端子与缓冲电容器的正极端子电连接,并且,平滑电容器部的负极端子与缓冲电容器的负极端子电连接。(The invention provides a motor driving device. A motor drive device which can reduce the heat loss of a smoothing capacitor and the heat loss of a snubber capacitor, is easy to construct, small in size and low in cost can be realized. The motor drive device includes: a smoothing capacitor unit having at least one smoothing capacitor provided between a converter circuit and an inverter circuit in a power conversion circuit that generates motor drive power; a snubber capacitor that suppresses a surge voltage of a power element that constitutes a part of the power conversion circuit; and a support plate provided for the smoothing capacitor unit, wherein an electrode terminal of the smoothing capacitor unit and an electrode terminal of the snubber capacitor are disposed in proximity to each other with the support plate interposed therebetween, a positive electrode terminal of the smoothing capacitor unit is electrically connected to a positive electrode terminal of the snubber capacitor, and a negative electrode terminal of the smoothing capacitor unit is electrically connected to a negative electrode terminal of the snubber capacitor.)

1. A motor drive device is characterized in that,

the motor drive device includes:

a smoothing capacitor unit having at least one smoothing capacitor that smoothes a voltage between a converter circuit and an inverter circuit in a power conversion circuit that generates motor drive power based on alternating-current power supplied from an alternating-current power source; and

a snubber capacitor for suppressing a surge voltage of a power element constituting a part of the power conversion circuit,

an electrode terminal of the smoothing capacitor unit is disposed in proximity to an electrode terminal of the snubber capacitor,

a positive electrode terminal of the electrode terminals of the smoothing capacitor part is electrically connected with a positive electrode terminal of the electrode terminals of the snubber capacitor, and a negative electrode terminal of the electrode terminals of the smoothing capacitor part is electrically connected with a negative electrode terminal of the electrode terminals of the snubber capacitor.

2. The motor drive device according to claim 1,

the electrode terminal of the smoothing capacitor unit is disposed to face the electrode terminal of the snubber capacitor.

3. The motor drive device according to claim 2,

the motor drive device further includes a support plate provided for the smoothing capacitor section,

the electrode terminal of the smoothing capacitor unit and the electrode terminal of the snubber capacitor are disposed to face each other with the support plate interposed therebetween.

4. The motor drive device according to any one of claims 1 to 3,

the motor drive device includes:

a 1 st conductor for electrically connecting the positive electrode terminal of the smoothing capacitor unit and the positive electrode terminal of the snubber capacitor; and

a 2 nd conductor for electrically connecting the negative electrode terminal of the smoothing capacitor unit and the negative electrode terminal of the snubber capacitor,

the 1 st conductor and the 2 nd conductor have portions close to each other.

5. The motor drive device according to claim 4,

the support plate is provided with a plurality of connections including a set of positive side connections and negative side connections,

the positive terminal of the smoothing capacitor part is electrically connected to the positive terminal of the snubber capacitor by the 1 st conductor of the positive side connection part via any one of the plurality of connection parts, and the negative terminal of the smoothing capacitor part is electrically connected to the negative terminal of the snubber capacitor by the 2 nd conductor of the negative side connection part via any one of the plurality of connection parts.

6. The motor drive device according to claim 4,

the positive electrode terminal and the negative electrode terminal of the smoothing capacitor unit and the positive electrode terminal and the negative electrode terminal of the snubber capacitor are screw type terminals.

7. The motor drive device according to claim 4,

the positive electrode terminal of the smoothing capacitor part and the 1 st conductor are electrically connected by soldering, and the positive electrode terminal of the snubber capacitor and the 1 st conductor are electrically connected by soldering,

the negative electrode terminal of the smoothing capacitor part is electrically connected to the 2 nd conductor by soldering, and the negative electrode terminal of the snubber capacitor part is electrically connected to the 2 nd conductor by soldering.

8. The motor drive device according to any one of claims 1 to 7,

the plurality of smoothing capacitor units are electrically connected in series.

9. The motor drive device according to any one of claims 1 to 8,

for the snubber capacitors, a plurality of the snubber capacitors are electrically connected in parallel.

Technical Field

The present invention relates to a motor drive device including a smoothing capacitor unit and a buffer capacitor.

Background

In a motor driving device for controlling driving of a motor in a machine tool, a forging press machine, an injection molding machine, an industrial machine, or various robots, ac power supplied from an ac power source is converted into dc power by a converter circuit (rectifier circuit) and output to a dc link, dc power in the dc link is converted into ac power by an inverter circuit, and the ac power is supplied as driving power to the motor provided for each drive shaft.

The "dc link" is a circuit portion that electrically connects the dc output side of the converter circuit and the dc input side of the inverter circuit, and may be referred to as a "dc link portion", a "dc link ring", a "dc ring portion", a "dc bus bar", or a "dc intermediate circuit". The dc link is provided with a large-capacity smoothing capacitor for suppressing a ripple component of a dc output of the converter circuit and smoothing a voltage input to the inverter circuit. The smoothing capacitor is also called a dc link capacitor.

Further, a power conversion circuit including an inverter circuit and a converter circuit of a PWM control method is configured by, for example, a bridge circuit including a semiconductor switching element called a power element and a diode connected in antiparallel to the semiconductor switching element, and performs power conversion by driving the power element so as to be turned on or off. In a power conversion circuit including a power element, a snubber capacitor having a good frequency characteristic is provided in order to suppress a surge voltage applied to the power element.

For example, as described in japanese patent application laid-open No. 2018-042384, an inverter structure is known: the inverter structure includes two inverter driving units that convert direct-current power into alternating-current power for driving two motors, respectively, and the inverter driving units are housed in one case, and includes: two switching circuit devices connected to the plurality of switching elements, each of which converts dc power into ac power and supplies the ac power to the respective motors; a capacitor unit including a smoothing capacitor for smoothing electric power input to the switching circuit devices and two sets of bus bars connected to the smoothing capacitor and supplying electric power to the two switching circuit devices, respectively; and a connection conductor that supplies electric power to the two switch circuit devices via the two sets of bus bars, the connection conductor being provided between the two switch circuit devices of the one housing.

For example, as disclosed in japanese patent No. 4675379, a motor drive circuit is known: the drive circuit of the motor drives the motor using a converter circuit and an inverter circuit, and is characterized by comprising: a printed circuit board for control circuit; and a lead frame molded substrate mounted on a component surface of the printed circuit board with a protrusion made of a mold resin for a spacer at a predetermined distance, and formed by integrally molding a metal plate lead and the mold resin, wherein an electronic component constituting the converter circuit and the inverter circuit for adjusting a height of the electronic component is mounted on the lead frame molded substrate so as to sandwich the protrusion for height adjustment integrally formed with the mold resin, and a snubber capacitor and a shunt resistor of the inverter circuit are mounted, an electrolytic capacitor of the converter circuit is mounted on the component surface of the printed circuit board, a power terminal of the electronic component is temporarily connected to the lead frame molded substrate, and thereafter, the metal plate lead of the lead frame molded substrate is bonded to the printed circuit board, the control wiring terminal of the electronic component is connected to the printed circuit board.

For example, as described in japanese patent application laid-open publication No. 2011-: the capacitor is characterized in that it comprises: a housing case having an opening; a plurality of capacitor elements housed in the housing case, and having a pair of electrode surfaces at ends of the housing case on the opening side and the bottom side; an opening-side bus bar disposed on the electrode surface of the capacitor element on the opening side; and a bottom bus bar disposed on the electrode surface of the capacitor element on the bottom side, wherein the plurality of capacitor elements are connected in parallel by the opening side bus bar and the bottom bus bar, and the opening side bus bar and the bottom bus bar each have a connection terminal for external device connection disposed in a state of not being close to a side surface of the capacitor element.

Disclosure of Invention

Problems to be solved by the invention

As described above, the motor drive device is provided with the smoothing capacitor and the buffer capacitor. As the smoothing capacitor, a large-capacity electrolytic capacitor is often used. When an overvoltage is applied, the electrolytic capacitor may have an opening for releasing gas in the vicinity of the terminal because the internal pressure may increase due to the gas generated by vaporization of the electrolyte in the electrolytic capacitor. The electrolytic capacitor has the following limitations: in order to prevent the electrolyte from leaking from the opening, the terminal must be provided so as not to face the vertical direction. In particular, in the electrolytic capacitor having the screw terminal, since the bus bar and the screw terminal are fastened by a screw, the restriction of the mounting position is severe. Therefore, it may result in that the physical distance between the smoothing capacitor and the buffer capacitor becomes long according to the configuration of the power element. As the distance between the smoothing capacitor and the snubber capacitor becomes longer, the inductance component between the smoothing capacitor and the snubber capacitor increases. Due to the inductance component, a potential difference is generated between the smoothing capacitor and the snubber capacitor, and the oscillation current increases, so that the heat loss of the smoothing capacitor and the heat loss of the snubber capacitor increase. In order to reduce this heat loss, for example, it is conceivable to select a capacitor having a large heat capacity for the smoothing capacitor and the buffer capacitor, and to provide a heat sink such as a cooling fan in the vicinity of the smoothing capacitor and the buffer capacitor. However, the larger the heat capacity of the capacitor, the higher the price. In addition, the provision of the radiator leads to an increase in cost, complication in structure, and enlargement of the motor drive device. Therefore, it is desirable to realize a motor drive device that can reduce heat loss of the smoothing capacitor and heat loss of the snubber capacitor, is easy to construct, is small, and is low in cost.

Means for solving the problems

According to an aspect of the present disclosure, there is provided a motor drive device, comprising: a smoothing capacitor unit having at least one smoothing capacitor that smoothes a voltage between a converter circuit and an inverter circuit in a power conversion circuit that generates motor drive power based on alternating-current power supplied from an alternating-current power source; and a snubber capacitor for suppressing a surge voltage of a power element constituting a part of the power conversion circuit; the electrode terminals of the smoothing capacitor unit are disposed close to the electrode terminals of the snubber capacitor, a positive electrode terminal of the electrode terminals of the smoothing capacitor unit is electrically connected to a positive electrode terminal of the electrode terminals of the snubber capacitor, and a negative electrode terminal of the electrode terminals of the smoothing capacitor unit is electrically connected to a negative electrode terminal of the electrode terminals of the snubber capacitor.

In the motor drive device, the electrode terminal of the smoothing capacitor unit may be disposed to face the electrode terminal of the snubber capacitor.

In the motor driving device, the motor driving device may further include a support plate on which the smoothing capacitor unit is provided, and the electrode terminal of the smoothing capacitor unit and the electrode terminal of the snubber capacitor may be disposed to face each other with the support plate interposed therebetween.

In the above motor drive device, the motor drive device may include: a 1 st conductor for electrically connecting the positive electrode terminal of the smoothing capacitor unit and the positive electrode terminal of the snubber capacitor; and a 2 nd conductor for electrically connecting the negative electrode terminal of the smoothing capacitor unit and the negative electrode terminal of the snubber capacitor, wherein the 1 st conductor and the 2 nd conductor have portions close to each other.

In the motor drive device, the support plate may be provided with a plurality of connection portions including a set of a positive side connection portion and a negative side connection portion, the positive terminal of the smoothing capacitor portion may be electrically connected to the positive terminal of the snubber capacitor by the 1 st conductor of the positive side connection portion via any one of the plurality of connection portions, and the negative terminal of the smoothing capacitor portion may be electrically connected to the negative terminal of the snubber capacitor by the 2 nd conductor of the negative side connection portion via any one of the plurality of connection portions.

In the motor drive device, the positive electrode terminal and the negative electrode terminal of the smoothing capacitor unit and the positive electrode terminal and the negative electrode terminal of the snubber capacitor may be screw type terminals.

In the motor drive device, the positive terminal of the smoothing capacitor unit and the 1 st conductor may be electrically connected by soldering, the positive terminal of the snubber capacitor unit and the 1 st conductor may be electrically connected by soldering, the negative terminal of the smoothing capacitor unit and the 2 nd conductor may be electrically connected by soldering, and the negative terminal of the snubber capacitor and the 2 nd conductor may be electrically connected by soldering.

In the motor drive device, the plurality of smoothing capacitor units may be electrically connected in series.

In the motor drive device, the plurality of snubber capacitors may be electrically connected in parallel to each other.

ADVANTAGEOUS EFFECTS OF INVENTION

According to an aspect of the present disclosure, a small-sized low-cost motor drive device with an easy structure can be realized, which can reduce heat loss of a smoothing capacitor and heat loss of a snubber capacitor.

Drawings

The present invention can be more clearly understood by referring to the following drawings.

Fig. 1A is a side view showing a mounting structure of a smoothing capacitor unit, a snubber capacitor, and a power element in a motor drive device according to an embodiment of the present disclosure.

Fig. 1B is a perspective view showing a mounting structure of a smoothing capacitor unit, a snubber capacitor, and a power element in a motor drive device according to an embodiment of the present disclosure.

Fig. 2 is a side view schematically showing a mounting structure of a smoothing capacitor unit, a snubber capacitor, and a power element in a motor drive device according to an embodiment of the present disclosure.

Fig. 3A is a diagram schematically showing a motor drive device that generates motor drive power based on ac power supplied from an ac power source, and is a circuit diagram showing the motor drive device.

Fig. 3B is a diagram schematically showing a motor drive device that generates motor drive power based on ac power supplied from an ac power supply, and is a circuit diagram for explaining generation of an oscillation current.

Fig. 4A is a plan view illustrating a 1 st aspect of a smoothing capacitor unit of a motor drive device according to an embodiment of the present disclosure.

Fig. 4B is a side view illustrating a 1 st aspect of a smoothing capacitor unit of a motor drive device according to an embodiment of the present disclosure.

Fig. 5A is a plan view illustrating a 2 nd aspect of a smoothing capacitor unit of a motor drive device according to an embodiment of the present disclosure.

Fig. 5B is a side view illustrating a 2 nd aspect of a smoothing capacitor unit of a motor drive device according to an embodiment of the present disclosure.

Fig. 6A is a side view illustrating a 3 rd aspect of a smoothing capacitor unit of a motor drive device according to an embodiment of the present disclosure.

Fig. 6B is a side view illustrating a 3 rd aspect of a smoothing capacitor unit of a motor drive device according to an embodiment of the present disclosure.

Fig. 6C is a plan view illustrating a 3 rd aspect of a smoothing capacitor unit of a motor drive device according to an embodiment of the present disclosure.

Fig. 7 is a diagram for explaining a positional relationship between a smoothing capacitor and a snubber capacitor in a conventional motor drive device.

Fig. 8 is a diagram for explaining a positional relationship between the smoothing capacitor unit and the snubber capacitor in the motor drive device according to the embodiment of the present disclosure.

Fig. 9 is a side view schematically showing an installation structure in which a plurality of smoothing capacitor units are connected in series in a motor drive device according to an embodiment of the present disclosure.

Fig. 10 is a side view schematically showing an installation structure in which a plurality of snubber capacitors are connected in parallel in a motor drive device according to an embodiment of the present disclosure.

Fig. 11A is a plan view illustrating a 1 st aspect of a mounting structure of a 1 st conductor and a 2 nd conductor of a motor drive device according to an embodiment of the present disclosure.

Fig. 11B is a side view illustrating a 1 st aspect of a mounting structure of a 1 st conductor and a 2 nd conductor of a motor drive device according to an embodiment of the present disclosure.

Fig. 12A is a plan view illustrating a 2 nd aspect of a mounting structure of a 1 st conductor and a 2 nd conductor of a motor drive device according to an embodiment of the present disclosure.

Fig. 12B is a side view illustrating a 2 nd form of a mounting structure of the 1 st conductor and the 2 nd conductor of the motor drive device according to the embodiment of the present disclosure.

Fig. 13A is a plan view illustrating a 3 rd aspect of a mounting structure of a 1 st conductor and a 2 nd conductor of a motor drive device according to an embodiment of the present disclosure.

Fig. 13B is a side view illustrating a 3 rd form of a mounting structure of a 1 st conductor and a 2 nd conductor of a motor drive device according to an embodiment of the present disclosure.

Fig. 14 is a side view illustrating a modification of the connection portion of the motor drive device according to the embodiment of the present disclosure.

Detailed Description

Hereinafter, a motor drive device including a smoothing capacitor unit and a buffer capacitor will be described with reference to the drawings. For easy understanding, these drawings are appropriately modified with respect to the scale. The form shown in the drawings is an example for implementation and is not limited to the illustrated embodiment.

Fig. 1A is a side view showing a mounting structure of a smoothing capacitor unit, a snubber capacitor, and a power element in a motor drive device according to an embodiment of the present disclosure. Fig. 1B is a perspective view showing a mounting structure of a smoothing capacitor unit, a snubber capacitor, and a power element in a motor drive device according to an embodiment of the present disclosure. Hereinafter, the same reference numerals are used to designate components having the same functions in different drawings. Fig. 2 is a side view schematically showing a mounting structure of a smoothing capacitor unit, a snubber capacitor, and a power element in a motor drive device according to an embodiment of the present disclosure. Fig. 3A is a diagram schematically showing a motor drive device that generates motor drive power based on ac power supplied from an ac power supply, and is a circuit diagram showing the motor drive device. Fig. 3B is a diagram schematically showing a motor drive device that generates motor drive power based on ac power supplied from an ac power supply, and is a circuit diagram for explaining generation of an oscillation current. In fig. 3A and 3B, for the sake of simplicity of explanation, only the portion corresponding to one phase is shown for the number of phases of the ac power supply 2 and the motor 3, but both the ac power supply 2 and the motor 3 may be single-phase or three-phase.

Before describing a motor drive device according to an embodiment of the present disclosure, a circuit and a generation principle of an oscillating current of the motor drive device that generates motor drive power based on ac power supplied from an ac power supply will be described with reference to fig. 3A and 3B.

As shown in fig. 3A and 3B, the motor drive device 1 includes: a converter circuit (rectifier circuit) 51 that converts ac power supplied from the ac power supply 2 into dc power and outputs the dc power to the dc link; and an inverter circuit 52 that converts the dc power of the dc link into ac power and outputs the ac power as motor drive power.

The inverter circuit 52 is constituted by a bridge circuit including a power element 15 as a semiconductor switching element and a diode connected in antiparallel to the power element 15. The converter circuit 51 does not include a power element when it is realized as a diode rectifier circuit, but is configured as a bridge circuit including a power element and a diode connected in antiparallel with the power element, as in the case of the inverter circuit 52, when it is realized as a rectifier circuit of the PWM control system. Examples of the power element include a unipolar transistor such as an FET, a bipolar transistor, an IGBT, a thyristor, and a GTO. In addition, a combination of a semiconductor switching element and a diode may be defined as a "power element", and such a power element is also referred to as a "power module".

A smoothing capacitor unit 11 for smoothing the voltage of the dc link is provided in the dc link between the converter circuit 51 and the inverter circuit 52. In the illustrated example, the smoothing capacitor unit 11 and the buffer capacitor 12 are provided on both the dc output side of the diode in the converter circuit 51 and the dc input side of the power element 15 in the inverter circuit 52.

Inductance components are generated by forming closed circuits (loop circuits) between the positive electrode terminals and the negative electrode terminals of the smoothing capacitor part 11 and between the positive electrode terminals and the negative electrode terminals of the snubber capacitor 12. This inductance component is denoted by reference numeral 31 in fig. 3B. In the inverter circuit 52, the upper power device 15-1 and the lower power device 15-2 are alternately turned on and off, thereby converting the dc power of the dc link into ac power. For example, when the lower power element 15-2 is turned off, the current i flows back through the diode D1 connected in antiparallel to the upper power element 15-1. At this time, a surge voltage of L × di/dt is generated by the internal inductance of the upper power element 15-1. By this surge voltage L × di/dt, a current flows into the snubber capacitor 12, and the voltage between the positive electrode terminal and the negative electrode terminal of the snubber capacitor 12 increases. As a result, a potential difference is generated between the smoothing capacitor unit 11 and the snubber capacitor 12 with the presence of the inductance component 31, and an oscillation current is generated. When the distance between the smoothing capacitor part 11 and the snubber capacitor 12 becomes longer, the inductance component between the smoothing capacitor part 11 and the snubber capacitor 12 increases, and the potential difference between the smoothing capacitor part 11 and the snubber capacitor 12 further increases, so that a larger oscillation current is generated between the smoothing capacitor part 11 and the snubber capacitor 12, and the heat loss of the smoothing capacitor part 11 and the heat loss of the snubber capacitor 12 increase.

In order to reduce the heat loss of the smoothing capacitor and the heat loss of the snubber capacitor due to the generation of the oscillation current, as shown in fig. 1A, 1B, and 2, a motor drive device 1 according to an embodiment of the present disclosure includes: a smoothing capacitor unit 11 having at least one smoothing capacitor for smoothing a voltage between a converter circuit and an inverter circuit in a power conversion circuit that generates motor drive power based on ac power supplied from an ac power source; a snubber capacitor 12 for suppressing a surge voltage of a power element 15 constituting a part of the power conversion circuit; and a support plate 13 provided for the smoothing capacitor unit 11.

The smoothing capacitor unit 11 may have at least one smoothing capacitor. The smoothing capacitor is constituted by, for example, an electrolytic capacitor, a film capacitor, or the like. When the smoothing capacitor unit 11 is formed of one smoothing capacitor, the smoothing capacitor is preferably large in capacity. In addition, when the smoothing capacitor unit 11 is formed of a plurality of smoothing capacitors, the smoothing capacitor unit 11 can be increased in capacity by combining a plurality of smoothing capacitors of small capacity. In the example shown in fig. 1A and 1B, the smoothing capacitor section 11 has 6 smoothing capacitors 11-1, 11-2, 11-3, 11-4, 11-5, 11-6 as an example. The connection relationship between the smoothing capacitors in the case where the smoothing capacitor unit 11 is composed of a plurality of smoothing capacitors is not particularly limited to the present embodiment. For example, the smoothing capacitor unit 11 is configured by connecting a group including the capacitors 11-1, 11-2, and 11-3 connected in parallel and a group including the capacitors 11-4, 11-5, and 11-6 connected in parallel in series.

The smoothing capacitor unit 11 has an electrode terminal 21 including a positive electrode terminal 21P and a negative electrode terminal 21N. The shape and position of the electrode terminal 21 including the positive electrode terminal 21P and the negative electrode terminal 21N shown in fig. 1A are merely an example, and other shapes and positions may be used.

The smoothing capacitor unit 11 is provided on the support plate 13. The support plate 13 may be a printed circuit board on which various components and wiring are mounted, or may be a molded plate on which various components and wiring are not mounted. Examples of the material constituting the support plate 13 include a phenolic plastic, paper epoxy resin (paper epoxy), glass epoxy resin (glass epoxy), alumina, or a combination thereof.

When the motor (not shown) driven by the motor drive device 1 is a three-phase ac motor, power elements 15U, 15V, and 15W are provided in the U-phase, V-phase, and W-phase, respectively. In the illustrated example, the power elements 15U, 15V, and 15W are mounted on the printed circuit board 16, for example. Alternatively, the power elements 15U, 15V, and 15W may be mounted on the surface of the support plate 13 opposite to the surface on which the smoothing capacitor unit 11 is provided. Reference numeral 23 denotes input/output terminals of the power elements 15U, 15V, and 15W. The shape and position of the input/output terminal 23 of each of the power elements 15U, 15V, and 15W shown in fig. 1B are merely an example, and other shapes and positions may be used.

The snubber capacitor 12 is formed of, for example, an electrolytic capacitor, a film capacitor, or the like. The snubber capacitor 12 is provided to each power element 15 and mounted to the printed circuit board 16. In the example shown in fig. 1A, 1B, and 2, the motor driven by the motor drive device 1 is a three-phase ac motor, and therefore the snubber capacitors 12U, 12V, and 12W are provided corresponding to the power elements 15U, 15V, and 15W. In addition, the snubber capacitor 12 has an electrode terminal 22 including a positive terminal 22P and a negative terminal 22N.

The electrode terminal 21 of the smoothing capacitor unit 11 and the electrode terminal 22 of the buffer capacitor 12 are disposed as close as possible to each other with the support plate 13 interposed therebetween. More preferably, the electrode terminal 21 of the smoothing capacitor unit 11 and the electrode terminal 22 of the buffer capacitor 12 are disposed to face each other with the support plate 13 interposed therebetween. However, when each of the smoothing capacitors 11-1 to 11-6 constituting the smoothing capacitor unit 11 includes an electrolytic capacitor, the smoothing capacitor unit 11 is disposed so that an opening portion for preventing an increase in internal pressure when an overvoltage is applied is not oriented in the vertical direction.

The positive electrode terminal 21P of the electrode terminals 21 of the smoothing capacitor part 11 and the positive electrode terminal 22P of the electrode terminals 22 of the snubber capacitor 12 are electrically connected to each other through the 1 st conductor 14-1. Further, the negative electrode terminal 21N of the electrode terminals 21 of the smoothing capacitor part 11 and the negative electrode terminal 22N of the electrode terminals 22 of the buffer capacitor 12 are electrically connected to each other through the 2 nd conductor 14-2.

The positive electrode terminal 21P and the negative electrode terminal 21N of the smoothing capacitor unit 11 and the positive electrode terminal 22P and the negative electrode terminal 22N of the snubber capacitor 12 are, for example, screw type terminals. In this case, the 1 st conductor 14-1 is electrically connected to the positive electrode terminal 21P of the smoothing capacitor unit 11 and the 1 st conductor 14-1 is electrically connected to the positive electrode terminal 22P of the snubber capacitor 12 by fastening with a conductive screw. The 2 nd conductor 14-2 is electrically connected to the negative electrode terminal 21N of the smoothing capacitor part 11 and the 2 nd conductor 14-2 is electrically connected to the negative electrode terminal 22N of the snubber capacitor 12 by fastening with a conductive screw.

Alternatively, the positive electrode terminal 21P of the smoothing capacitor part 11 and the 1 st conductor 14-1, and the positive electrode terminal 22P of the snubber capacitor 12 and the 1 st conductor 14-1 are electrically connected by soldering, respectively. The negative electrode terminal 21N of the smoothing capacitor part 11 and the 2 nd conductor 14-2, and the negative electrode terminal 22N of the snubber capacitor 12 and the 2 nd conductor 14-2 are electrically connected by soldering, respectively.

Examples of the 1 st conductor 14-1 and the 2 nd conductor 14-2 include a bus bar, a conductive cable, and a conductive member with an insulating film having an outer peripheral surface covered with an insulating film. The bus bar and the conductive cable are conductors for conducting a large amount of current, and are manufactured by sheet metal working a metal such as copper, brass, or aluminum. In the case of the conductive member with an insulating film, the conductive member portion is also a conductor for conducting a large-capacity current, and is manufactured by sheet-metal working of a metal such as copper, brass, or aluminum. In particular, when the 1 st conductor 14-1 and the 2 nd conductor 14-2 are each formed of an insulating film-coated conductive member, the insulating film is peeled off at the connection portion where the insulating film-coated conductive member is connected to the respective electrode terminals of the smoothing capacitor portion 11 and the buffer capacitor portion 12, and the conductive member is exposed to the outside. The conductive cable and the conductive member with the insulating coating may have high rigidity, or may have flexibility. In the present embodiment, the 1 st conductor 14-1 and the 2 nd conductor 14-2 are constituted by bus bars, respectively, as an example.

As described above, according to the present embodiment, the electrode terminal 21 of the smoothing capacitor unit 11 and the electrode terminal 22 of the snubber capacitor 12 are disposed as close as possible to each other with the support plate 13 interposed therebetween. Therefore, an electrical path between the positive electrode terminal 21P of the smoothing capacitor part 11 and the positive electrode terminal 22P of the electrode terminal 22 of the buffer capacitor 12 and an electrical path between the negative electrode terminal 21N of the smoothing capacitor part 11 and the negative electrode terminal 22N of the electrode terminal 22 of the buffer capacitor 12 become short, and therefore, the inductance component decreases. This reduces the oscillation current, and therefore, can suppress heat loss of the smoothing capacitor unit 11 and heat loss of the buffer capacitor 12. Further, since the heat loss of the smoothing capacitor part 11 and the heat loss of the buffer capacitor 12 are suppressed, the heat sink can be eliminated or reduced, and the cost reduction, the simplification of the structure, and the downsizing of the motor drive device can be achieved. For example, when the heat sink is formed by a cooling fan, the current for operating the cooling fan can be eliminated or reduced, and therefore, the power consumption of the motor drive device can be reduced.

Next, several forms of the smoothing capacitor unit 11 are described. Here, as an example, in the 1 st and 2 nd aspects, the smoothing capacitor unit 11 is configured by a plurality of smoothing capacitors, and in the 3 rd aspect, the smoothing capacitor unit 11 is configured by one smoothing capacitor.

Fig. 4A is a plan view illustrating a 1 st aspect of a smoothing capacitor unit of a motor drive device according to an embodiment of the present disclosure. Fig. 4B is a side view illustrating a 1 st aspect of a smoothing capacitor unit of a motor drive device according to an embodiment of the present disclosure.

The smoothing capacitor unit 11 of the 1 st embodiment shown in fig. 4A and 4B is configured by electrically connecting a plurality of (8 in the example shown in fig. 4A and 4B) smoothing capacitors 11-7 to 11-14 to each other, similarly to the smoothing capacitor unit 11 shown in fig. 1A, 1B, and 2, and is provided on the supporting plate 13. The smoothing capacitors 11-7 to 11-14 are electrically connected by soldering. By combining a plurality of small-capacity smoothing capacitors 11-7 to 11-14, the capacity of the smoothing capacitor unit 11 can be increased. The connection relationship between the smoothing capacitors in the case where the smoothing capacitor unit 11 is composed of a plurality of smoothing capacitors is not particularly limited to the present embodiment. For example, the smoothing capacitor unit 11 is configured by connecting a group including capacitors 11-7 to 11-10 connected in parallel and a group including capacitors 11-11 to 14 connected in parallel in series. The smoothing capacitor unit 11 is configured by connecting smoothing capacitors 11-7 to 11-14 in series, for example. The smoothing capacitor unit 11 is configured by connecting smoothing capacitors 11-7 to 11-14 in parallel, for example.

Fig. 5A is a plan view illustrating a 2 nd aspect of a smoothing capacitor unit of a motor drive device according to an embodiment of the present disclosure. Fig. 5B is a side view illustrating a 2 nd aspect of a smoothing capacitor unit of a motor drive device according to an embodiment of the present disclosure.

The smoothing capacitor unit 11 of the 2 nd embodiment shown in fig. 5A and 5B is configured by electrically connecting a plurality of (two in the example shown in fig. 5A and 5B) screw terminal type smoothing capacitors 11-15, 11-16 to each other. By combining a plurality of small-capacity smoothing capacitors 11-15, 11-16, the smoothing capacitor unit 11 can be increased in capacity. Similarly to the embodiment 1, the connection relationship between the smoothing capacitors when the smoothing capacitor unit 11 is formed of a plurality of smoothing capacitors is not particularly limited to the present embodiment. For example, the smoothing capacitor unit 11 is configured by connecting smoothing capacitors 11 to 15 and 11 to 16 in series. The smoothing capacitor unit 11 is configured by connecting smoothing capacitors 11-15 and 11-16 in parallel, for example.

Fig. 6A is a side view illustrating a 3 rd aspect of a smoothing capacitor unit of a motor drive device according to an embodiment of the present disclosure. Fig. 6B is a side view illustrating a 3 rd aspect of a smoothing capacitor unit of a motor drive device according to an embodiment of the present disclosure. Fig. 6C is a plan view illustrating a 3 rd aspect of a smoothing capacitor unit of a motor drive device according to an embodiment of the present disclosure. For example, in the case where the voltage of the dc link is relatively low, the smoothing capacitor section 11 may be constituted by one smoothing capacitor 11 to 17.

Fig. 7 is a diagram for explaining a positional relationship between a smoothing capacitor and a snubber capacitor in a conventional motor drive device. In the example shown in fig. 7, the negative Z-axis direction is set as the vertical direction. In the example shown in fig. 7, the smoothing capacitor 110 and the substrate 160 on which the snubber capacitor 120 is provided are separately shown for the sake of simplicity of the drawing, but actually, the smoothing capacitor 110 is provided so as to overlap the substrate 160 in the positive Y-axis direction or the negative Y-axis direction.

The smoothing capacitor 110 is often constituted by an electrolytic capacitor capable of securing a large capacity with a small volume. When an overvoltage is applied, the electrolytic capacitor may have an opening for releasing gas in the vicinity of the terminal because the internal pressure may increase due to the gas generated by vaporization of the electrolyte in the electrolytic capacitor. Therefore, the electrolytic capacitor has the following limitations: in order to prevent the electrolyte from leaking from the opening, the terminal must be provided so as not to face the vertical direction. In the example shown in fig. 7, smoothing capacitor 110 is arranged such that positive electrode terminal 210P and negative electrode terminal 210N face upward along the Z axis (positive Z axis direction). On the other hand, if the snubber capacitor 120(120U, 120V, 120W) has to be arranged below the Z axis of the substrate 160 of the motor drive device 100 in terms of design, the electric path between the smoothing capacitor 110 and the snubber capacitor 120 becomes long, and therefore the inductance component becomes large. Since the large inductance component is present, the potential difference between the smoothing capacitor 110 and the snubber capacitor 120 becomes large, and as a result, the oscillation current also becomes large, and therefore, the heat loss of the smoothing capacitor 110 and the heat loss of the snubber capacitor 120 become large. As described above, since the restriction on the installation location of the screw terminal type large electrolytic capacitor is particularly severe, the electric path between the smoothing capacitor 110 and the snubber capacitor 120 becomes long, and the heat loss of the smoothing capacitor 110 and the heat loss of the snubber capacitor 120 become particularly large.

Fig. 8 is a diagram for explaining a positional relationship between the smoothing capacitor unit and the snubber capacitor in the motor drive device according to the embodiment of the present disclosure. In the example shown in fig. 8, the negative Z-axis direction is set as the vertical direction. In the example shown in fig. 8, the smoothing capacitor part 11 and the printed circuit board 16 on which the snubber capacitor 12 is provided are separately shown for the sake of simplicity of the drawing, but actually, the smoothing capacitor part 11 is provided so as to overlap in the positive Y-axis direction or the negative Y-axis direction with respect to the printed circuit board 16.

Here, a case will be described, as an example, in which the smoothing capacitor unit 11 of the 1 st embodiment shown in fig. 4A and 4B is provided in the motor drive device 1. The smoothing capacitor part 11 is formed by electrically connecting the smoothing capacitors 11-7 to 11-14 to each other, and is provided on the support plate 13.

The support plate 13 is provided with a connection portion 40 including a set of a positive side connection portion 41P and a negative side connection portion 41N. When the snubber capacitors 12(12U, 12V, 12W) are disposed below the Z axis of the printed circuit board 16 of the motor drive device 1, for example, the connection portion 40 is provided below the Z axis of the support plate 13 as shown in the drawing. The positive connection portion 41P and the negative connection portion 41N are formed of a conductive member such as a pad penetrating both surfaces of the support plate 13. The positive electrode terminal 21P of the smoothing capacitor part 11 is electrically connected to the positive side connection part 41P via a 1 st conductor (not shown in fig. 8), and the negative electrode terminal 21N of the smoothing capacitor part 11 is electrically connected to the negative side connection part 41N via a 2 nd conductor (not shown in fig. 8). The positive connection portion 41P of the support plate 13 is also electrically connected to the positive terminal 22P of the snubber capacitor 12 via the 1 st conductor. The negative connection portion 41N of the support plate 13 is also electrically connected to the negative terminal 22N of the snubber capacitor 12 via a 2 nd conductor.

For example, the positive side connection portion 41P and the negative side connection portion 41N may be holes penetrating the support plate 13, and the 1 st conductor and the 2 nd conductor may be respectively penetrated through the holes. In this case, the positive electrode terminal 21P of the smoothing capacitor part 11 is directly electrically connected to the positive electrode terminal 22P of the snubber capacitor 12 through the 1 st conductor penetrating the positive side connection part 41P formed of a hole. The negative electrode terminal 21N of the smoothing capacitor part 11 is directly electrically connected to the negative electrode terminal 22N of the snubber capacitor 12 through the 2 nd conductor penetrating the negative side connection part 41N formed of a hole.

Since the snubber capacitor 12 is provided below the Z-axis together with the connection unit 40 in this manner, the electrode terminal 21 of the smoothing capacitor unit 11 and the electrode terminal 22 of the snubber capacitor 12 are arranged close to each other. Therefore, an electrical path between the positive electrode terminal 21P of the smoothing capacitor part 11 and the positive electrode terminal 22P of the electrode terminal 22 of the buffer capacitor 12 and an electrical path between the negative electrode terminal 21N of the smoothing capacitor part 11 and the negative electrode terminal 22N of the electrode terminal 22 of the buffer capacitor 12 become short, and therefore, the inductance component decreases. This reduces the oscillation current, and therefore, can suppress heat loss of the smoothing capacitor unit 11 and heat loss of the buffer capacitor 12. In the present embodiment, the small-capacity smoothing capacitors 11-7 to 11-14 in the smoothing capacitor unit 11 can be disposed at relatively free positions, and therefore, the degree of freedom in design is higher than that of the smoothing capacitor 110 formed of a screw-type terminal-type large-capacity electrolytic capacitor as shown in fig. 7.

The number and connection relationship of the smoothing capacitors in the smoothing capacitor unit 11 may be determined appropriately according to, for example, the magnitude of the dc link voltage and the withstand voltage of each smoothing capacitor. For example, the larger the number of smoothing capacitors connected in series in the smoothing capacitor unit 11, the larger the dc link voltage can be handled.

Fig. 9 is a side view schematically showing an installation structure in which a plurality of smoothing capacitor units are connected in series in the motor drive device according to the embodiment of the present disclosure. By connecting a plurality of smoothing capacitor units 11 in series, a larger dc link voltage can be handled. In this case, the plurality of smoothing capacitor units 11 are provided on the support plate 13.

The snubber capacitors 12 are provided corresponding to the power elements 15 of the respective phases, but the snubber capacitors 12 may be connected in parallel at portions corresponding to the 1 phase to increase the capacitance. Fig. 10 is a side view schematically showing an installation structure in which a plurality of snubber capacitors are connected in parallel to a motor drive device according to an embodiment of the present disclosure. Since the capacitance can be increased by connecting a plurality of snubber capacitors 12 in parallel as necessary, a larger surge voltage can be suppressed. In this case, a plurality of snubber capacitors 12 are provided on the printed circuit board 16.

Next, several embodiments of the mounting structure of the 1 st conductor 14-1 and the 2 nd conductor 14-2 for further suppressing the oscillation current are described. Since a closed circuit (loop circuit) is formed between each positive electrode terminal and each negative electrode terminal of the smoothing capacitor unit 11 and between each positive electrode terminal and each negative electrode terminal of the snubber capacitor 12, a large or small amount of inductance component is generated. Then, the size of the inductance component 31 is reduced by disposing the 1 st conductor 14-1 and the 2 nd conductor 14-2 so as to have portions close to each other, the 1 st conductor 14-1 electrically connecting the positive electrode terminal 21P of the smoothing capacitor unit 11 and the positive electrode terminal 22P of the snubber capacitor 12, and the 2 nd conductor 14-2 electrically connecting the negative electrode terminal 21N of the smoothing capacitor unit 11 and the negative electrode terminal 22N of the snubber capacitor 12.

Fig. 11A is a plan view illustrating a 1 st aspect of a mounting structure of a 1 st conductor and a 2 nd conductor of a motor drive device according to an embodiment of the present disclosure. Fig. 11B is a side view illustrating a 1 st aspect of a mounting structure of a 1 st conductor and a 2 nd conductor of a motor drive device according to an embodiment of the present disclosure. In the example shown in fig. 11A and 11B, the support plate 13 is not shown for the sake of simplicity of the drawings. According to the 1 st aspect shown in fig. 11A and 11B, the 1 st conductor 14-1 and the 2 nd conductor 14-2 overlap in the Y-axis direction near the middle.

Fig. 12A is a plan view illustrating a 2 nd aspect of a mounting structure of a 1 st conductor and a 2 nd conductor of a motor drive device according to an embodiment of the present disclosure. Fig. 12B is a side view illustrating a 2 nd form of a mounting structure of the 1 st conductor and the 2 nd conductor of the motor drive device according to the embodiment of the present disclosure. In the example shown in fig. 12A and 12B, the support plate 13 is not shown in the drawings for simplicity. The 2 nd form shown in fig. 12A and 12B is also the same as the 1 st form shown in fig. 11A and 11B, and the 1 st conductor 14-1 and the 2 nd conductor 14-2 are overlapped in the Y axis direction near the middle. However, the 2 nd embodiment shown in fig. 12A and 12B differs from the 1 st embodiment shown in fig. 11A and 11B in the arrangement in the vicinity of the connection portion between the smoothing capacitor portion 11 and the 1 st conductor 14-1 and the 2 nd conductor 14-2 and the arrangement in the vicinity of the connection portion between the buffer capacitor portion 12 and the 1 st conductor 14-1 and the 2 nd conductor 14-2.

Fig. 13A is a plan view illustrating a 3 rd aspect of a mounting structure of a 1 st conductor and a 2 nd conductor of a motor drive device according to an embodiment of the present disclosure. Fig. 13B is a side view illustrating a 3 rd form of a mounting structure of a 1 st conductor and a 2 nd conductor of a motor drive device according to an embodiment of the present disclosure. In the example shown in fig. 13A and 13B, the support plate 13 is not shown in the drawings for simplicity. According to the 3 rd form shown in fig. 13A and 13B, the 1 st conductor 14-1 and the 2 nd conductor 14-2 are overlapped in the Z-axis direction in the vicinity of the middle.

In any of the above-described 1 st to 3 rd embodiments, insulation should be secured between the 1 st conductor 14-1 and the 2 nd conductor 14-2. For example, the 1 st conductor 14-1 and the 2 nd conductor 14-2 may be separated from each other to such an extent that insulation can be secured, or either one or both of the 1 st conductor 14-1 and the 2 nd conductor 14-2 may be covered with an insulating coating.

Next, a modification of the connecting portion 40 provided in the support plate 13 will be described.

Fig. 14 is a side view illustrating a modification of the connection portion of the motor drive device according to the embodiment of the present disclosure. In the example shown in fig. 14, the negative Z-axis direction is set as the vertical direction. In the example shown in fig. 14, the support plate 13 and the printed circuit boards 16(16A, 16B, 16C) provided for the snubber capacitors 12 are illustrated separately for the sake of simplicity of the drawing, but in actuality, any of the printed circuit boards 16A, 16B, 16C is provided so as to overlap the support plate 13 in the positive Y-axis direction. The illustrated positions of the snubber capacitors 12 on the printed circuit boards 16A, 16B, and 16C are examples, and the snubber capacitors 12 may be provided at positions other than the illustrated positions on the printed circuit board 16.

If the plurality of connection portions 40A, 40B, and 40C having the positive side connection portion 41P and the negative side connection portion 41N are provided in advance on the support plate 13 so as to be shifted in the Z-axis direction, a connection portion that minimizes the electrical path between the electrode terminal 21 of the smoothing capacitor portion 11 and the electrode terminal 22 of the smoothing capacitor portion 12 can be selected in accordance with the position of the smoothing capacitor portion 12 on the printed circuit board 16 in the Z-axis direction. In the example shown in fig. 14, the number of the connection portions provided in the support plate 13 is three as an example, but two or four or more connection portions may be provided.

The positive electrode terminal 21P of the smoothing capacitor unit 11 and the positive electrode terminal 22P of the snubber capacitor 12 are electrically connected by the 1 st conductor 14-1 passing through the positive side connection unit 41P provided at any one of the plurality of connection units 40A, 40B, 40C of the support plate 13, and the negative electrode terminal 21N of the smoothing capacitor unit 11 and the negative electrode terminal 22N of the snubber capacitor 12 are electrically connected by the 2 nd conductor 14-2 passing through the negative side connection unit 41N provided at any one of the plurality of connection units 40A, 40B, 40C of the support plate 13.

For example, the printed circuit board 16A is provided so as to overlap in the positive Y-axis direction of the support plate 13, and the buffer capacitor 12 is provided in a portion of the printed circuit board 16A located above in the Z-axis direction, and in this case, the connection portion 40A is selected. In this case, the positive electrode terminal 21P of the smoothing capacitor part 11 is electrically connected to the positive side connection part 41P of the connection part 40A via the 1 st conductor 14-1 (not shown in fig. 14), and the negative electrode terminal 21N of the smoothing capacitor part 11 is electrically connected to the negative side connection part 41N of the connection part 40A via the 2 nd conductor 14-2 (not shown in fig. 14). The positive side connection portion 41P of the connection portion 40A on the support plate 13 is also electrically connected to the positive terminal 22P of the snubber capacitor 12 on the printed circuit board 16A via the 1 st conductor 14-1. The negative side connection portion 41N of the connection portion 40A on the support plate 13 is also electrically connected to the negative terminal 22N of the snubber capacitor 12 on the printed circuit board 16A via the 2 nd conductor 14-2.

For example, the printed circuit board 16B is provided so as to overlap in the positive Y-axis direction of the support plate 13, and the connection portion 40B is selected in this case, in which the printed circuit board 16B is provided with the snubber capacitor 12 at the middle portion in the Z-axis direction. In this case, the positive electrode terminal 21P of the smoothing capacitor part 11 is electrically connected to the positive side connection part 41P of the connection part 40B via the 1 st conductor 14-1 (not shown in fig. 14), and the negative electrode terminal 21N of the smoothing capacitor part 11 is electrically connected to the negative side connection part 41N of the connection part 40B via the 2 nd conductor 14-2 (not shown in fig. 14). The positive side connection portion 41P of the connection portion 40B on the support plate 13 is also electrically connected to the positive terminal 22P of the snubber capacitor 12 on the printed circuit board 16B via the 1 st conductor 14-1. The negative side connection portion 41N of the connection portion 40B on the support plate 13 is also electrically connected to the negative terminal 22N of the snubber capacitor 12 on the printed circuit board 16B via the 2 nd conductor 14-2.

For example, the printed circuit board 16C is provided so as to overlap in the positive Y-axis direction of the support plate 13, and the buffer capacitor 12 is provided in a portion of the printed circuit board 16C located below in the Z-axis direction, in which case the connection portion 40C is selected. In this case, the positive electrode terminal 21P of the smoothing capacitor part 11 is electrically connected to the positive side connection part 41P of the connection part 40C via the 1 st conductor 14-1 (not shown in fig. 14), and the negative electrode terminal 21N of the smoothing capacitor part 11 is electrically connected to the negative side connection part 41N of the connection part 40C via the 2 nd conductor 14-2 (not shown in fig. 14). The positive side connection portion 41P of the connection portion 40C on the support plate 13 is also electrically connected to the positive terminal 22P of the snubber capacitor 12 on the printed circuit board 16C via the 1 st conductor 14-1. The negative side connection portion 41N of the connection portion 40C on the support plate 13 is also electrically connected to the negative terminal 22N of the snubber capacitor 12 on the printed circuit board 16C via the 2 nd conductor 14-2.

In this way, the electrode terminal 21 of the smoothing capacitor unit 11 and the electrode terminal 22 of the buffer capacitor 12 are disposed close to each other via any of the plurality of connection units 40A, 40B, and 40C. Therefore, the connection portion on the support plate 13, which is configured to reduce the inductance component between the positive electrode terminal 21P of the smoothing capacitor unit 11 and the positive electrode terminal 22P of the electrode terminal 22 of the snubber capacitor 12 and between the negative electrode terminal 21N of the smoothing capacitor unit 11 and the negative electrode terminal 22N of the electrode terminal 22 of the snubber capacitor 12 (that is, which is configured to more effectively suppress the heat loss of the smoothing capacitor unit 11 and the heat loss of the snubber capacitor 12), can be selected from the plurality of connection portions 40A, 40B, and 40C. Therefore, if a plurality of connection portions (connection portions 40A, 40B, and 40C in the example shown in fig. 14) are provided in advance in the support plate 13, it is possible to design the buffer capacitor 12 so as to be compatible with one type of support plate 13 regardless of the position on the printed circuit board 16, and therefore, it is possible to reduce the stock of the support plate 13 on which the smoothing capacitor unit 11 is provided. As a result, the motor drive device 1 can be reduced in cost and simplified in structure.

According to one embodiment of the present disclosure, a small-sized low-cost motor drive device having an easy structure, which can reduce heat loss of a smoothing capacitor and heat loss of a snubber capacitor, can be realized.