Motor drive device in which electrical power flows into or out of a power device via a busbar.

Abstract

Motor drive device (1) comprising a power unit (10), wherein this power unit (10) forms part of a power converter circuit for generating motor drive power and has an input / output terminal (11); a circuit board (20) having an opening (22); and a busbar (30) which is connected to both the power unit (10) and the circuit board (20), where the busbar (30) a plate-shaped first connection section (31) which is connected to the input / output terminal (11), a second connection section (33) which is connected to the circuit board (20), and a connecting section (32) which extends between the first connecting section (31) and the second connecting section (33) and passes through the opening (22), exhibits.

Description

General state of the art 1. Field of invention

[0001] The present invention relates to a motor drive device in which electrical power flows into or out of a power device via a busbar. 2. Description of the state of the art

[0002] In motor drive devices that power motors in machine tools, forging presses, industrial machinery, or various types of robots, power supplied by an AC or DC source is converted into motor drive power by a power converter circuit. Power converter circuits include the inverter, which converts input DC power into AC power and outputs it, and the rectifier (also called a "converter"), which converts input AC power into DC power and outputs it. For example, AC power supplied by an AC source is temporarily converted into DC power by the rectifier and then converted back into AC power by the inverter, which then supplies this AC power as motor drive power.

[0003] A power converter circuit, comprising an inverter and a PWM rectifier, consists, for example, of a bridge circuit. This bridge circuit incorporates semiconductor switching elements with high capacitance, referred to as power devices, and antiparallel diodes connected to them. Power conversion is achieved through the on / off operation of these power devices. Since a relatively high current flows through the power device, a busbar is used for the electrical connection between the power device and an electrode terminal. The busbar is made of a metal such as copper, brass, aluminum, or similar materials and is formed, for example, by sheet metal fabrication.Furthermore, the power converter circuit incorporates various electrical circuits, such as a main circuit consisting of the power device's bridge circuit, a control circuit for regulating the power conversion, a detection circuit for detecting the current or voltage used for various processes like power conversion or anomaly detection, and a limiter circuit to protect the circuits from surge voltages generated when the power device is switched on or off. These electrical circuits are comprised of various components such as resistors, capacitors, inductors, diodes, FETs (field-effect transistors), operational amplifiers, photocouplers, analog-to-digital converters (ADCs), digital-to-analog converters (DACs), or various integrated circuits.Often, the goal of grouping these components onto a printed circuit board (PCB) is to reduce size and simplify circuit wiring. In a motor drive device, the PCB, on which the various components are mounted, is positioned near the power unit and connected to it electrically and physically. For example, a detection circuit is implemented on the PCB that detects the current flowing into or out of the power unit via a busbar, or that detects the potential of the busbar connected to the power unit. In this case, the busbar is not only electrically connected to the input / output terminal of the power unit, but also electrically connected to the wiring on the PCB that leads to the detection circuit.

[0004] For example, as described in patent disclosure JP H06-302 932 A, a printed wiring plate is known which consists of an electrode connection made of a bent metal plate of a highly conductive metal, which has at a certain location a screw through-hole and claw sections for soldering to the printed wiring plate, and the printed wiring plate having fixing openings suitable for inserting the claw sections of the electrode connection and to which wiring with components on the printed wiring plate is carried out, and having a punched opening at a position which, in a state in which the claw sections of the electrode connection have been inserted into the fixing openings, is located directly below the screw fastening opening.wherein the printed wiring plate and the electrode connection are fixed to each other by inserting the claw sections into the fixing openings of the printed wiring plate and soldering them to it.

[0005] For example, as described in patent disclosure JP 2011 - 234 488 A, a power converter device (1) comprises several semiconductor modules (16A, 16B) which form part of a power converter circuit; a control circuit section (25) which is electrically connected to the semiconductor modules (16A, 16B) and controls the semiconductor modules (16A, 16B); a busbar (23) which is electrically connected to the semiconductor modules (16A, 16B) and supplies power to the semiconductor modules (16A, 16B); a terminal block (24) which is equipped with the busbar (23) and a high-voltage cable (30) which supplies the power from the outside and to which the busbar (23) and the high-voltage cable (30) are electrically connected; and a receiving housing (26) which accommodates the semiconductor modules (16A, 16B), the busbar (23) and the terminal block (24), known, which is characterized in thatthat the receiving housing (26) comprises a first insertion opening (29) and a second insertion opening (38) into which the high-voltage cable (30) can be inserted, a working opening (35) formed opposite the terminal block (24) for performing the operation of connecting the high-voltage cable (30) and the terminal block (24), an insertion opening cover (39) to close the opening formed by the first insertion opening (29) and the second insertion opening (38) into which the high-voltage cable (30) is not inserted, and a working opening cover (36) to close the working opening, wherein the first through-opening (29) and the second through-opening (38) are formed across the terminal block (24) at opposite positions, and the working opening (35) is formed in a direction that is orthogonal to the connection direction of the first through-opening (29) and the second through-opening (38). is.,

[0006] For example, a connection structure of a high-current circuit board is known from utility model disclosure JP H07-29 874 U, which is characterized in that a screw element, which is guided from one side to the other through the high-current circuit board, protrudes on both sides of the high-current circuit board and fixes a terminal element, and a conductor or a high-current element, which rests on the other side of the terminal element, is fastened and fixed. Brief description of the invention

[0007] As described above, in a motor drive device where a circuit board is arranged near a power device to which a busbar is electrically and physically connected, this busbar is also connected to the electrical wiring formed on the circuit board.

[0008] For example, it is conceivable to electrically and physically fix the busbar, power supply, and circuit board by securing the busbar and the input / output terminal of the power supply with a single screw, such that the circuit board is clamped between the busbar and the input / output terminal of the power supply. If, in this case, the screw hole in the busbar is formed by deburring, the strength of the screw fastening of the busbar and the power supply can be ensured, but the heat loss will be significant because the input / output terminal of the power supply will be in contact with the end face of the deburred area of ​​the busbar, resulting in a small contact area.Furthermore, the difficulty of performing deburring on a narrow component such as a busbar is high, leading to an increase in the manufacturing costs of the motor drive device. While a screw hole without deburring is used to reduce manufacturing costs, and the busbar and the input / output terminal of the power unit are electrically connected via a bridge formed on the circuit board, vibration resistance is poor and heat loss is high.

[0009] To increase vibration resistance, it is also conceivable, for example, to clamp the circuit board by screwing the busbar and the input / output terminal of the power unit, and by screwing the busbar and the circuit board between the busbar and the input / output terminal of the power unit, thus electrically and physically fixing the busbar, the power unit, and the circuit board. Since screw holes are created at two points on the busbar in this case, the screw fastening places stress on the busbar, reducing its thickness. Furthermore, performing deburring and screw hole machining at two points on a narrow component like a busbar increases the machining difficulty, leading to higher manufacturing costs for the motor drive device.

[0010] Consequently, it is desirable to design a connection structure for the busbar, power unit, and circuit board in a motor drive device with low heat loss, high strength, high vibration resistance, and low cost.

[0011] According to one form of the present disclosure, a motor drive device comprises a power unit, wherein this power unit forms part of a power converter circuit for generating motor drive power and has an input / output terminal; a printed circuit board having an opening; and a busbar that is connected to both the power unit and the printed circuit board, wherein the busbar has a plate-shaped first terminal section that is connected to the input / output terminal, a second terminal section that is connected to the printed circuit board, and a connecting section that extends between the first terminal section and the second terminal section and passes through the opening. Simple explanation of the drawings

[0012] The present invention will be understood more clearly by reference to the accompanying drawings below. Fig. Figure 1 is an oblique view showing the connection structure of a busbar, a circuit board and a power device in a motor drive device according to an embodiment of the present disclosure. Fig. Figure 2 is an oblique view showing a conductive retaining block in the motor drive device according to an embodiment of the present disclosure. Fig. Figure 3 is a sectional view showing the connection structure of the busbar, the circuit board and the power unit in the motor drive device according to an embodiment of the present disclosure. Fig. 4A is an oblique view showing a state-of-the-art connection setup that connects a printed circuit board in such a way that it is clamped between a busbar (deburred) and a power device. Fig. 4B is a sectional view showing the state-of-the-art connection setup, which connects the circuit board in such a way that it is clamped between the busbar (deburred) and the power device. Fig. Figure 5 is a sectional view showing a state-of-the-art connection setup that connects a printed circuit board in such a way that it is clamped between a busbar (not deburred) and a power device. Fig. Figure 6A is an oblique view showing a state-of-the-art connection setup in which both the connection of a busbar and a power device and the connection of the busbar and a circuit board are made by means of screw fastening. Fig. Figure 6B is a sectional view showing the connection setup according to the state of the art, in which both the connection of the busbar and the power device and the connection of the busbar and the circuit board are made by means of screw fastening. Fig. Figure 7 is an oblique view when ribs are formed on the busbar and the conductive retaining block of the motor drive device according to an embodiment of the present disclosure in order to ensure bending strength. Fig. Figure 8A is an oblique view showing the conductive retaining block, on which ribs are formed, in the motor drive device according to an embodiment of the present disclosure. Fig. 8B is a sectional view along line AA' in Fig. 8A, which shows the conductive retaining block, on which ribs are formed, in the motor drive device according to an embodiment of the present disclosure. Fig. Figure 9 is a front view showing, by way of example, a printed circuit board in which the conductive retaining block in the motor drive device acts as a drip protection wall and as a wall forming a ventilation duct according to an embodiment of the present disclosure. Detailed explanation

[0013] With reference to the drawings, a motor control device in which electrical power flows into or out of a power unit via a busbar is explained below. For ease of understanding, the scale of these drawings has been arbitrarily changed. The embodiment shown in the drawings represents an example of the design, but there is no limitation to the embodiment shown.

[0014] Fig. Figure 1 is an oblique view showing the connection structure of a busbar, a printed circuit board, and a power device in a motor drive device according to one embodiment of the present disclosure. If components in the various drawings are designated with the same reference numerals, this indicates that they have the same function. Fig. Figure 2 is an oblique view showing a conductive retaining block in the motor drive device according to an embodiment of the present disclosure. Fig. Figure 3 is a sectional view showing the connection structure of the busbar, the circuit board and the power unit in the motor drive device according to an embodiment of the present disclosure.

[0015] A motor drive device 1 comprises a power unit 10, a printed circuit board 20, and a busbar 30. Furthermore, a conductive retaining block 40, serving as a mounting / connection element for holding the busbar 30, is formed on the printed circuit board 20 in the motor drive device 10. The device in which a motor driven by the motor drive device 1 is installed is, for example, a machine tool, a robot, a forging press, an injection molding machine, an industrial machine, a type of electrical device, a railway, a motor vehicle, an aircraft, or the like.

[0016] The power device 10 is a semiconductor switching element that forms part of a power converter circuit for generating motor drive power in the motor drive device 1. Examples of the power converter circuit include an inverter and a PWM rectifier, and the like. The power converter circuit consists, for example, of a bridge circuit comprising power devices and diodes connected antiparallel to it, and performs the power conversion by switching the power devices on and off. Examples of the power device are unipolar transistors such as FETs, bipolar transistors, IGBTs, thyristors, GTOs, or the like, whereby the type of power device itself does not restrict the present embodiment. It can also be other power devices.

[0017] The power device 10 has an input terminal into which current flows and an output terminal from which current flows. In the present embodiment, the terminal of the power device to which the busbar 30 is connected can be either the input terminal or the output terminal. Hereinafter, the terminal of the power device 10 to which the busbar 30 is connected is referred to as the "input / output terminal 11".

[0018] The circuit board 20 incorporates various electrical circuits, such as a control circuit for regulating the power conversion of the power converter circuit that the power device 10 includes, a detection circuit for detecting the current or voltage used for various processes such as power conversion or anomaly detection, or the like, or a limiter circuit to protect the circuits from surge voltages that occur when the power device is switched on / off, or the like. These electrical circuits are formed from various components such as resistors, capacitors, inductors, diodes, FETs (field-effect transistors), operational amplifiers, photocouplers, analog-to-digital converters (ADCs), digital-to-analog converters (DACs), or various integrated circuits.These components are mounted on the printed circuit board 20, and the individual components are connected by electrical wiring according to the function of the circuits they comprise. Of the various electrical circuits formed on the printed circuit board 20, the detection circuit, which detects the current flowing into or out of the power device 10 via the busbar 30, or which detects the potential of the busbar 30 connected to the power device 10, and the limiter circuit, and the like, are electrically connected to the busbar 30. Hereinafter, that electrical wiring on the printed circuit board 20 which is electrically connected to the busbar 30 is referred to as "electrical wiring 21".The electrical wiring 21 can be formed inside the printed circuit board 20 (embedded in the interior of the printed circuit board 20, formed on a surface 20A, or formed on a second surface 20B of the printed circuit board 20). In the example shown, the electrical wiring 21 is formed inside the printed circuit board 20.

[0019] Furthermore, the circuit board 20 has an opening 22. Details regarding the size of the opening 22 will be described later.

[0020] The busbar 30 is connected to both the power unit 10 and the circuit board 20. The busbar 30 is a conductor for carrying a relatively high current, is made of a metal such as copper, brass, aluminum, or the like, and is manufactured, for example, by sheet metal fabrication.

[0021] The busbar 30 has a plate-shaped first connection section 31, which is attached to the input / output terminal 11 of the power device 10, a second connection section 33, which is connected to the printed circuit board 20, and a connecting section 32, which extends between the first connection section 31 and the second connection section 33 and passes through the opening 22 of the printed circuit board 20. The first connection section 31 is located on the side of the first area 20A of the printed circuit board 20, and the second connection section 33 is located on the side of the second area 20B of the printed circuit board 20. The first connection section 31 and the second connection section 33 are positioned such that the printed circuit board 20 is located between them.In the opposite direction to that of the connecting section 32, a third connecting section 34 is formed, and a power source or other power converter circuit can be electrically connected further forward than the third connecting section 34.

[0022] The connecting section 32 extends in a direction that intersects both the first connecting section 31 and the second connecting section 33, and runs from the side of the second surface 20B of the printed circuit board 20 through the opening 22 to the side of the first surface 20A of the printed circuit board 20. In the example shown, the connecting section 32 runs through the opening 22 along the direction normal to the second surface 20B of the printed circuit board 20 (that is, in the direction perpendicular to the second surface 20B of the printed circuit board 20). As an alternative example, an arrangement of the connecting section 32 is also possible in which it runs through the opening 22 such that the direction of the connecting section 32 through the opening 22 and the direction normal to the second surface 20B of the printed circuit board 20 form a certain angle.

[0023] The first connection section 31 and the connecting section 32 are formed by a curved section, and the connecting section 32 and the second connection section 33 are formed by a curved section, so that the busbar 30 has a curved structure. In the illustrated example, the first connection section 31 and the connecting section 32 intersect substantially orthogonally, and the connecting section 32 and the second connection section 33 intersect substantially orthogonally, so that the busbar 30 has a stepped structure, which represents one embodiment of the curved structure. Since the busbar 30 thus has a stepped structure and can therefore accommodate tolerances when the busbar 30 is attached to the circuit board 20 and the power unit 10, the manufacture of the motor drive device 1 is simplified.Since the busbar 30 itself is formed by a stepped bending process of a conductive metal sheet, its manufacture is also simple. The elasticity (spring-like properties) of the stepped design increases its strength (fracture resistance) and vibration resistance. In the example shown, the second connection section 33 and the third connection section 34 are also connected via a bent section; however, as an alternative example, the second connection section 33 and the third connection section could also be connected without a bent section.

[0024] The first connection section 31 of the busbar 30 is electrically and physically connected to the input / output terminal 11 of the power device 10 by means of a screw fastening using a screw 50. The screw 50 is preferably made of a conductive material. Since the first connection section 31 is plate-shaped and its plate-shaped area is in contact with the input / output terminal 11 of the power device 10, the electrical connection area is large, thus reducing heat loss. Consequently, a large current can flow from the busbar 30 to the power device 10 or from the power device 10 to the busbar 30.

[0025] When attaching the busbar 30 to the power unit 10, the first connection section 31 and the connecting section 32 of the busbar 30 are inserted from the side of the second surface 20B of the circuit board 20 to the side of the first surface 20A of the circuit board 20, where the input / output terminal 11 of the power unit 10 is located. Then, the first connection section 31 and the input / output terminal 11 of the power unit 10 are fixed together by screwing them with the screw 50.

[0026] For this purpose, a screw insertion opening 35 is provided in the first connection section 31 of the busbar 30 for fixing the first connection section 31 and the input / output terminal 11 of the busbar 10 by screwing. Furthermore, the opening 22 of the circuit board 20 has at least such dimensions and shape that the busbar 30 can be inserted and, in addition, a slot formed in the upper surface of the head of the screw 50 can be turned by a tool. Even better, the opening 22 of the circuit board 20 has such dimensions and shape that the upper surface of the head of the screw 50 can be seen from the side of the circuit board 20 on which the second connection section 33 is located when the connecting section 32 of the busbar 30 has been inserted into the opening 22 and fixed to the first connection section 31 by means of the screw 50.In particular, the opening 22 of the printed circuit board 20 has a dimension and shape that is larger than the thickness of the connecting section 32 (the end face parallel to the second surface 20B of the printed circuit board 20) together with the area of ​​the plate-shaped first connecting section 31 (the surface parallel to the second surface 20B of the printed circuit board 20). If the opening 22 of the printed circuit board 20 has such a dimension and shape that the plate-shaped first connecting section 31 can be seen, then, for example, a worker can easily insert the connecting section 32 into the opening 22 and attach it to the first connecting section 31 via the screw 50, and maintenance work after manufacturing will also be easy.Since the attachment of the busbar 30 to the power device 10 becomes easier, but the area on which components can be set up on the circuit board 20 becomes smaller as the size of the opening 22 of the circuit board 20 increases, it is advantageous to determine the dimensions and size of the opening 22 of the circuit board 20 taking into account the balance between ease of attachment and the area for setting up components.

[0027] The second connection section 33 of the busbar 30 is electrically and physically connected to the circuit board 20 via the conductive retaining block 40. The second connection section 33 and the conductive retaining block 40 are fixed to each other by means of a screw 51. For this purpose, a screw insertion hole 36 is formed in the second connection section 33 of the busbar 30 for fixing the second connection section 32 of the busbar 30 and the conductive retaining block 40 by screwing them together.

[0028] The conductive retaining block 40 is mounted on the circuit board 20 and is located between the second connection section 33 of the busbar 30 and the circuit board 20. Since the busbar, which has a stepped design, is connected to the circuit board 20 via the conductive retaining block 40, the vibration resistance is high.

[0029] The conductive retaining block 40 has an upper plate section 44, which is attached to the second terminal section 33 of the busbar 30, and a pair of side plate sections 43. These side plate sections extend from a pair of edges of the upper plate section 44 in a direction intersecting the upper plate section 44 and are spaced apart from one another. The upper plate section 43 supports the second terminal section 33 of the busbar 30, which is attached to the upper plate section 44, at a position remote from the circuit board 20. More precisely, a screw insertion hole 41 is provided in the upper plate section 41 for fastening the second terminal section 33 of the busbar 30 and the conductive retaining block 40 to each other by screwing. Furthermore, circuit board terminal sections 42 are provided at the ends of the side plate sections 43 for electrically connecting the electrical wiring 21 of the circuit board 20 and the conductive retaining block 40 by soldering.The printed circuit board terminal sections 42, for example, have a claw shape with spring properties (elasticity). They firmly fix the conductive retaining block 40 to the second surface 20B of the printed circuit board 20 by inserting it through openings formed in the printed circuit board 20, and electrically connect the electrical wiring 21 formed inside the printed circuit board 20 and the conductive retaining block 40. The shape of the printed circuit board terminal sections 42 can also be a different shape than the claw shape shown. For example, the electrical connection between the printed circuit board terminal sections 42 and the electrical wiring 21 formed inside the printed circuit board 20 can also be made via a bridge formed on the printed circuit board 20.

[0030] In this way, the busbar 30 is electrically and physically fixed to the input / output terminal 11 of the power unit 10 by screwing it to the first connection section 31 using screw 50, and electrically and physically fixed to the conductive retaining block 40 to the second connection section 33 using screw 51. The conductive retaining block 40 is electrically and physically fixed to the circuit board 20 via the circuit board terminal sections 42. The busbar 30 is electrically connected to the input / output terminal 11 of the power unit 10 at the first connection section 31 and electrically connected to the electrical wiring 21 of the circuit board 20 at the second connection section 33 via the conductive retaining block 40.

[0031] If the embodiment of the present disclosure is used for a connection setup for conducting current from the busbar 30 into the power device 10, by setting the impedance of the conductive holding block 40 to be greater than the input impedance of the power device 10, it can be ensured that a smaller current (the continuous arrow in Fig. 1) than the current flowing from busbar 30 into power device 10 (the broken arrows in Fig. 1) from the busbar 30 to the electrical wiring 21 of the circuit board 20. Therefore, by appropriately regulating the impedance of the conductive holding block 40, it is possible to split the current flowing in the busbar 30 into a large current flowing to the power device 10 and a small current flowing to the electrical wiring 21 of the circuit board 20.

[0032] And if the embodiment of the present disclosure is used for a connection setup for conducting current from the power device 10 to the busbar 30, by adjusting the impedance of the conductive holding block 40 to be greater than the impedance of the busbar 30, it can be ensured that a smaller current (in Fig. (1 not shown) as the current that exits from the power device 10 to the busbar 30 (in Fig. (1 not shown), flows via the busbar 30 and the conductive holding block 40 to the electrical wiring 21 of the circuit board 20. Therefore, by appropriately regulating the impedance of the conductive holding block 40, it is possible to split the current exiting the power device 10 into a large current that flows to the third terminal section 34 of the busbar 30, and a small current that flows via the conductive holding block 40 to the electrical wiring 21 of the circuit board 20.

[0033] Fig. 4A is an oblique view showing a state-of-the-art connection setup that connects a printed circuit board in such a way that it is clamped between a busbar (deburred) and a power device. Fig. Figure 4B is a sectional view showing the state-of-the-art connection setup, which connects the circuit board in such a way that it is clamped between the busbar (deburred) and the power device. Fig. 4A and Fig. Figure 4B does not show the electrical wiring, which is formed on a printed circuit board 120 and is electrically connected to a busbar 130.

[0034] As in Fig. 4A and Fig. As shown in Figure 4B, a conventional connection setup is used in which the circuit board 120 is clamped between the busbar 130 and an input / output terminal 111 of the power device 110, whose screw holes were formed by deburring, and the busbar 130 and the power device 110 as well as the circuit board 120 are electrically and mechanically fixed by fastening the busbar 130 and the input / output terminal 111 of the power device by a single screw 150. If the screw hole on the busbar 30, through which the screw 150 is inserted, is formed by a deburring operation, the strength of the screw fastening of the busbar 130 and the power unit 110 is ensured, but the heat loss is large because the input / output terminal 111 of the power unit 140 comes into contact with the end surface of the deburring area 131 of the busbar 130 and therefore the contact area is small.Furthermore, the difficulty level of performing deburring on an element with a small width such as the 130 busbar is high, which leads to an increase in the manufacturing costs of the motor drive device.

[0035] Fig. Figure 5 is a sectional view showing a state-of-the-art connection setup that connects a printed circuit board by clamping it between a busbar (not deburred) and a power device. Fig. Figure 5 does not include a representation of the electrical wiring, which is formed on the circuit board 120 and is electrically connected to the busbar 130.

[0036] As in Fig. As shown in Figure 5, the conventional method involves electrically and physically connecting the un-deburred busbar 130 and the power unit 110 by clamping the circuit board 120 between the busbar 130 and the input / output terminal 111 of the power unit 110. This connection is achieved via a bridge 170. Therefore, the heat loss is significant compared to a direct connection of the busbar 130 and the input / output terminal 111 of the power unit 110. Furthermore, the difficulty of deburring a narrow element like the busbar 130 is high, leading to an increase in the manufacturing costs of the motor drive device.

[0037] Fig. Figure 6A is an oblique view showing a state-of-the-art connection setup in which both the connection of a busbar and a power device and the connection of the busbar and a circuit board are made by means of screw fastening. Fig. Figure 6B is a sectional view showing the state-of-the-art connection setup, in which both the busbar and power device are connected and the busbar and the circuit board are connected by screw fastening. Fig. 6A and Fig. Figure 6B does not include a representation of the electrical wiring formed on the circuit board 120 and electrically connected to a busbar 130.

[0038] As in Fig. 6A and Fig. As shown in Figure 6B, a conventional connection setup is used to increase vibration resistance. In this setup, the circuit board 120 is clamped between the busbar 130 and the input / output terminal 111 of the power unit 110 by means of a screw 150, and the busbar 130 and the circuit board 120 are clamped between the busbar 130 and the input / output terminal 111 of the power unit 110 by means of a screw 160. This electrically and physically secures the busbar 130, the power unit 110, and the circuit board 120. Since this connection setup requires screw holes at two points on the busbar 130, the tightening of the screws places stress on the busbar 130, reducing its thickness.Furthermore, performing deburring and screw hole machining at two points on a narrow element such as the 130 busbar increases the machining difficulty, leading to an increase in the manufacturing costs of the motor drive device.

[0039] In contrast, according to the embodiment of the present disclosure, the first connection section 31 of the busbar 30 is plate-shaped, and contact with the input / output terminal 11 of the power device 10 is made through this plate-shaped area, resulting in a large electrical contact area. Consequently, heat loss can be reduced, and a large current can flow from the busbar 30 to the power device 10 or from the power device 10 to the busbar 30. Since the busbar 30 has a stepped structure and can therefore accommodate tolerances when attaching the busbar 30 to the circuit board 20 and to the power device 10, the manufacture of the motor drive device 1 is simplified. Furthermore, since the busbar 30 itself is formed by a stepped bending process of a conductive metal sheet, its manufacture is also simple.The elasticity (spring-like property) of the stepped structure increases its strength (breakage resistance) and vibration resistance. Furthermore, by appropriately regulating the impedance of the conductive retaining block 40, a small current of a desired magnitude can be directed from the current flowing in the busbar 30 into the electrical wiring 21 of the circuit board 21.

[0040] Then, with reference to Fig. 7, Fig. 8A and Fig. Figure 8B explains a modification of the busbar 30 and the conductive retaining block 40. To further ensure bending strength, ribs can be formed on the busbar 30 and the conductive retaining block 40.

[0041] Fig. Figure 7 is an oblique view when ribs are formed on the busbar and the conductive retaining block of the motor drive device according to an embodiment of the present disclosure in order to ensure bending strength. Fig. Figure 8A is an oblique view showing the conductive retaining block, on which ribs are formed, in the motor drive device according to an embodiment of the present disclosure. Fig. 8B is a sectional view along line AA' in Fig. Figure 8A shows the conductive retaining block, on which ribs are formed, in the motor drive device according to an embodiment of the present disclosure. The ribs 37 and 38 formed on the busbar 30 and the ribs 45 formed on the conductive retaining block 40 have a protrusion and a depression, which are obtained by a press machining operation on the plate-shaped metal elements. For example, the ribs 45 on the conductive retaining block 40 have, as in Fig. 8A and Fig. Figure 8B shows a raised area 45A and a recessed area 45B. The ribs 37, 38, and 45 can be formed at any point on the busbar 30 and the conductive retaining block 40 where bending strength is required. In the example shown, rib 37 is formed in the connecting section 32 of the busbar 30, and rib 38 is formed in the third connection section 34. On the conductive retaining block 40, the ribs 45 are formed in the side plate sections 43. By forming ribs on the busbar 30 and the conductive retaining block 40 in this way, the strength (the fracture resistance) and the vibration resistance are increased.

[0042] Then, with reference to Fig. Figure 9 explains another application example for the motor control device 1, which has a connection structure as described above. Since the pair of side plate sections 43 of the conductive support structure 40 has comparatively large dimensions, the side plate sections 43 of the conductive support structure 40 mounted on the circuit board 20 can also act as a drip guard for other components on the circuit board 20 or they can act as a wall to form a ventilation channel for other components on the circuit board 20.

[0043] Fig. Figure 9 is a front view showing an exemplary printed circuit board (PCB) in which the conductive support block in the motor drive device, according to one embodiment of the present disclosure, acts as a drip guard and as a wall forming a ventilation duct. Here, an example is given in which the PCB 20 is installed in a vertical position in the motor drive device 1. In the illustrated example, the conductive support block 40, for supporting the busbar 30, components 71 to 75 such as chip resistors and the like, and an electrolytic capacitor 60 are installed on the second surface 20B of the PCB 20. A fan 80 is installed above the PCB 20 for cooling the components mounted on the PCB 20. The conductive support block 40 is designed with such dimensions and shape that it projects laterally from the second connection section 33 of the busbar 30.

[0044] If, for example, the motor drive device 1 is used as a drive source for driving a motor in a machine tool, cutting fluid may drip down from above the circuit board 20. If the components 71 to 75, to which no cutting fluid should adhere, are positioned below the conductive retaining block 40, the conductive retaining block 40 is positioned as shown in Fig.Figure 9 shows the conductive retaining block 40 mounted on the printed circuit board 20 such that the source of the cutting fluid flow and the components 71 to 75 are located on opposite sides of the side plate sections 43 of the conductive retaining block 40. This redirects the flow of the cutting fluid dripping from above, as it impacts the side plate sections 43 of the conductive retaining block 40, to a direction along the side plate sections 43, preventing the cutting fluid from adhering to the components 71 to 75. In this way, the side plate sections 43 of the conductive retaining block 40 can act as a drip-protection barrier for other components mounted on the printed circuit board 20.

[0045] Furthermore, heat-generating components such as the electrolytic capacitor 60 or the like are cooled by an airflow generated by the fan 80. In the illustrated example, the fan 80 generates an airflow directed from the underside to the top side of the circuit board 20 (as indicated by arrows 92). However, if the conductive mounting block 40 is mounted on the circuit board 20 such that the longitudinal direction of the side plate sections 43 of the conductive mounting block 40 has the orientation shown by arrow 93, the airflow drawn up by the fan 80 strikes the electrolytic capacitor 60. This allows the electrolytic capacitor 60 to be cooled. In this way, the side plate sections 43 of the conductive mounting block 40 can act as a wall, forming a ventilation channel to other components mounted on the circuit board 20.

[0046] Since the orientation of the side plate sections of the conductive retaining block 40 is relatively free, as long as the conductive retaining block 40 can support the busbar 30 at the second connection section 33, the angle formed by the orientation 93 of the side plate sections 43 of the conductive retaining block 40 and the orientation 93 of the busbar can be appropriately determined depending on the positional relationship between the source for the flow of the cutting fluid and the components to which no cutting fluid should adhere, or the positional relationship between the fan 80 and the components to be cooled.

[0047] According to the embodiment of the present disclosure, a motor drive device can be designed which has a connection structure of the busbar and the power device as well as the printed circuit board with low heat loss, high strength, high vibration resistance and low cost.

Claims

[1] Motor drive device (1) comprising a power unit (10), wherein this power unit (10) forms part of a power converter circuit for generating motor drive power and has an input / output terminal (11); a circuit board (20) having an opening (22); and a busbar (30) which is connected to both the power unit (10) and the circuit board (20), where the busbar (30) a plate-shaped first connection section (31) which is connected to the input / output terminal (11), a second connection section (33) which is connected to the circuit board (20), and a connecting section (32) which extends between the first connecting section (31) and the second connecting section (33) and passes through the opening (22), exhibits. [2] Motor drive device (1) according to claim 1, wherein the connecting section (32) extends in a direction that crosses both the first connecting section (31) and the second connecting section (33). [3] Motor drive device (1) according to claim 2, wherein the busbar (30) has a stepped structure consisting of the first connection section (31), the connecting section (32) and the second connection section (33). [4] Motor drive device (1) according to one of claims 1 to 3, further comprising a conductive retaining block (40) which is arranged on the circuit board (20) and is located between the second connection section (33) and the circuit board (20). [5] Motor drive device (1) according to claim 4, wherein the conductive retaining block (40) a screw insertion opening (41) for fastening the second connection section (33) of the busbar (30) and the conductive retaining block (40) to each other by screwing them together, and circuit board terminal sections (42) for electrically connecting an electrical wiring formed on the circuit board (20) and the conductive retaining block (40), exhibits. [6] Motor drive device (1) according to claim 4, wherein the conductive retaining block (40) an upper plate section (44) which is attached to the second connecting section (33), and a pair of side plate sections (43) extending from a pair of edges of the upper plate section (44) in a direction intersecting the upper plate section (44) and spaced apart from each other, exhibits wherein the pair of side plate sections (43) is attached at its ends to the printed circuit board (20) and supports the second connecting section (33) attached to the upper plate section (44) at a position away from the printed circuit board (20). [7] Motor drive device (1) according to one of claims 4 to 6, wherein the conductive retaining block (40) has a dimension and shape projecting laterally from the second connecting section (33) and forms a drip protection wall for other components of the printed circuit board (20). [8] Motor drive device (1) according to one of claims 4 to 7, wherein the conductive retaining block (40) has a dimension and shape projecting laterally from the second connecting section (33) and forms a cooling channel for other components of the printed circuit board (20). [9] Motor drive device (1) according to any one of claims 4 to 8, wherein the conductive retaining block (40) has ribs (45) which ensure the bending strength of the conductive retaining block (40). [10] Motor drive device (1) according to one of claims 1 to 9, wherein the busbar (30) has ribs (37, 38) which ensure the bending strength of the busbar (30).

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