FR2718396A1 - Circuit arrangement for electric motor powered by battery. - Google Patents

Abstract

On a common carrier element (12) which may be a heat sink, are mounted at least one capacitor (14, 16) and a switch (18), covered at least partially by an assembly of two conductive plates (22, 24) separated by an insulating layer. These plates are connected one to the negative terminal, and the other to the positive terminal of the battery, and the capacitors and the switches are connected to these plates, the lower plate having bushings for this purpose. Advantageously, the connections to the motor are made using plate-shaped bus bars (46, 48), which improve the shielding effect produced by the plate assembly (22, 24).

Description

The invention relates to a circuit arrangement for the operation of

  less an electric motor powered by battery. It relates more specifically to such an arrangement fitted on a industrial truck having at least one capacitor and at least one semiconductor switch clocked which are arranged on a plate-shaped carrier element and can be electrically connected to a

control part.

  It is known to pulse electrical motors for the drive and the drive system.

  lifting of battery powered forklifts.

  When using thyristors, the control frequency is relatively low. When using electronic power switches, for example field effect transistors (FETs), MOS field effect transistors (MOS-FETs), or insulated gate bipolar transistors (IGBTs), etc., preference is given to higher control frequencies, lying in the

range from 7 to 16 kHz.

  The power portion of a circuit arrangement for operating an electric motor includes, for example, electronic power switches, freewheel diodes, capacitors, and heat sinks. The structure of the known power parts comprising for example an external connection technique leads to considerable leakage inductances and thus, if necessary, to high overvoltages and periodic peaks of voltage. These phenomena make it necessary to design the semiconductor switches accordingly. To provide protection against the influences of external leakage inductances, i.e. between the battery and the power section, strong capacitors are used which are usually in the form of electrolytic capacitors. The evoked voltage spikes do not only affect the semiconductor power switches, they can also have an adverse effect on the operation of the control part, which is also done electronically. Finally, voltage peaks can also disturb the environment, for example through interference, disturbance of the telephone network, parasites of other electronic devices. The object of the invention is to provide a circuit arrangement for the operation of at least one battery-powered electric motor fitted to a handling trolley, made in a compact manner and which reduces stress or load, by means of spikes. voltage, of semiconductor switches powered at high frequencies. In order to achieve this result, it is provided according to the invention that at least one capacitor and one semiconductor switch module are arranged on a common carrier element which, according to a preferred modality of

  the invention may be composed of a heat sink.

  The semiconductor switches of the type used are generally made in modules which contain for example a row of pellets. The use of the module concept, however, should not be considered restrictively. It only involves providing semiconductor switches with a mounting surface

electrically insulated.

  According to the invention above these electrical components and covering at least partially, are arranged two electrically conductive material plates, slightly spaced apart from each other, and between which there is a thin insulating layer, a plate that can connected to the minus terminal and the other to the plus terminal of the battery, and the terminals of the electrical components are respectively connected to a plate by a connection directed to the plate arrangement, the bottom plate and the insulating layer having bushings for the passage of connections to the upper plate. It is possible to envisage uses for which only one electrolytic capacitor is sufficient. Usually, a multiplicity of electrolytic capacitors is however necessary. These form

  then a battery of capacitors.

  Above the electrical components mentioned, the invention provides a plate arrangement consisting of two parallel plates covering the components and between which there is an insulating layer. It is certainly possible to keep the plates apart from each other by insulating spacers, the separating insulation being constituted by air. However, it is preferable to prefer a configuration of the invention according to which

  an insulating sheet is disposed between the plates.

  The gap between the plates is therefore extremely small, eg equal to 0.1 mm. In the presence of operating voltages of 24 volts for example, this isolation

however, is largely sufficient.

  Each of the mentioned components has at least one connection that is connected, through the plates, to a positive or negative potential. Since the plates can be connected to at least one connection of the vehicle battery, the poles or connections of the electrical components are led to the plate arrangement and connected accordingly to the two plates. For this purpose, the component-facing plate, or bottom plate, has bushings, as well as the insulating layer, for the passage of the connections to the outer plate or top plate. The use of screws simultaneously makes it possible to provide a mechanical fastening of the

  plate on the components or vice versa.

  The mentioned plates form current supply manifolds for the electrical components and simultaneously provide, by their arrangement, the compensation of magnetic fields as well as a reduced coupling of the electromagnetic radiation in neighboring elements. If, for example, the outer plate is connected to the minus pole, it forms an efficient shield against the electromagnetic waves produced below the plate arrangement and therefore can not reach the outside. The plate arrangement also allows connections to the electrical components to remain extremely short, greatly reducing leakage inductances. The inductance formed by the arrangement of the plates themselves is extremely low due to the very low effective area. The reduced leakage inductance naturally leads to greatly reduced overvoltages charging the semiconductor switches. Semiconductor switches can therefore be operated to their power limit or they can be

designed with less power.

  In addition, the arrangement described allows an extremely compact construction, which is very interesting for a

  use on industrial trucks.

  As has been mentioned, it is normally necessary to have several electrolytic capacitors on the carrier element. According to the invention, there is therefore at least one row of electrolytic capacitors on the carrier element, which row is arranged in

  parallel with a row of semiconductor modules.

  Another embodiment provides that the connections of the battery to the plates are located at opposite ends of the row of capacitors. This means that for example the positive connection of a capacitor is very close to the battery connection while the negative connection, arranged diagonally opposite, is relatively distant and vice versa. In this way, a symmetrical current distribution is obtained which has an additional effect

  favorable on the objectives pursued.

  Electric transport vehicles often have two electric motors, namely for movement and for the lifting system. According to one embodiment of the invention, the capacitors and the semiconductor modules for the two electric motors are arranged together on the carrier element, and are connected to the arrangement of the plates, all the capacitors being connected in parallel. This allows you to use any capacitors for lifting or moving. Normally, no lifting or lowering is done during the movement and no movement is made during lifting. This reduces the total capacity that would be needed

  for separate power parts.

  The semiconductor modules for the two power sections are preferably arranged by

groups on the carrier element.

  The height of the terminals on the capacitors, which are arranged at the upper end of the latter, must be differentiated because of the height

  different from the two plates of the plate arrangement.

  Since the pattern of holes in the plate arrangement must be realized according to the intended arrangement pattern of the capacitors or their terminals, the embodiment according to the invention at the same time ensures what is called a protection against the reverse poles. For example, if it is impossible, due to an erroneous arrangement of the capacitors, to make the necessary connection with the plates, a verification must be carried out

corresponding.

  One embodiment of the invention provides, in the upper plate of the plate arrangement, the formation of a large surface elevation for receiving the bottom plate. The top plate can then be attached, at the edge, to the modules or capacitors with

  screws or similar elements, as appropriate.

  The structure of the power section according to the invention allows, according to one embodiment of the invention, to install on the outer plate a plate containing the control portion. The described shielding largely excludes the electromagnetic waves emitted by the power portion from acting on components of the control part. This reduces the compactness of the entire electrical or electronic circuit arrangement for motor operation. Most of the time, the control or regulation of the electric motor requires a measurement of the current, for example armature current. According to one embodiment of the invention, a current sensor,

  advantageously without contact is arranged on the plate.

  The power output is fed to the motor connection terminal through the sensor, for example an annular shaped current sensor on the underside of the board via an extension of the motor connection connected to the modules to be connected. semiconductor. The annular shaped current sensor may be constituted for example by a Hall effect component. The current detection is thus carried out without contact. The current sensor does not require any effort

  separate maintenance and no additional interface.

  As has been mentioned, the circuit arrangement according to the invention is compact and in total reduces the existing leakage inductances. It allows the assembly of the control part and the power part for two or more electric motors also if necessary. The design of the power part, ie the number of electrolytic modules and capacitors, can also be modified

  freely without modifying the basic structure.

  The invention is described below in a more

detailed using the drawings.

  Figure 1 shows, in perspective, the part of

  power of a circuit arrangement according to the invention.

  Figure 2 shows the same power section as the

  Figure 1, but with the terminal screws removed.

  Figure 3 shows a power portion similar to Figure 2, but for a three-phase power supply. FIG. 4 is a section through the power portion shown in FIGS. 1 to 3. FIG. 5 shows the arrangement of a plate for a control portion on the power portion according to FIG.

Figure 1.

  FIG. 6 schematically shows the arrangement of the power section with the part of

control according to Figure 5.

  Figure 7 is a front view of the arrangement according to

Figure 6.

  A power portion 10 shown in FIG. 1, for example for the operation of an electric displacement motor and an electric motor for the hoisting system of a industrial truck, has a heat sink 12 of the plates, whose upper face is stepped. In the lower part of this upper face are arranged two rows of capacitors (capacitor bank), for example electrolytic capacitors, among which there is a cylindrical capacitor 14 or 16. On the heat sink 12 is arranged, slightly elevated and roughly in the middle, a row of eight

  modules 18 constituting semiconductor switches.

  It is possible to provide all types of semiconductor switches that can be envisaged, for example MOSFETs, FETs, IGBTs, static induction transistors (SIT) or the like. They are suitable for operating with a relatively high frequency, for example between 7 and 16 kHz. Above the described arrangement of circuit components, there is provided a plate arrangement 20, consisting of an upper plate 22 which extends above the capacitor bank and partially above the modules 18. Under the plate 22 extends another plate 24 of which Figure 1 shows only part. The plates 22, 24 have for example a thickness of 1 mm. The plate 22 is further housed in an elevation 24a which is formed by folding the upper plate 22 in the marginal areas. With a terminal point 26, the top plate 22 forms a negative connection. With a terminal point

  28, the bottom plate 24 forms the positive connection.

  The terminal points 26, 28 are firmly connected to a plastic part which houses at the same time the different capacitors of the capacitor bank and which is further provided with two projections on which the plates 22, 24 are attached to the using screws. The plastic part is fixed to the heat sink by means of pressure pins. The capacitors 14, 16 are electrically conductive connected to the upper and lower plates 22, 24 by means of contact screws 30 or 32. The modules 18 are also connected to the plates 22, 24 by means of contact screws 34 or 36. The basic sandwich-like structure of the plates is visible in FIG. 4. It can be seen that a sheet 38, made of electrically insulating material, is disposed between the plates 22, 24. The plates can be made of sheet metal relatively thin conductive metal, for example aluminum or copper. Leaf

  38 is relatively thin, 0.1 mm thick, for example.

  Power lines 40, 42 shown in Figure 2 lead to the terminals of the battery. The capacitors according to Figure 1 are simply suggested by a symbol in Figure 4. It is seen that the positive and negative connections are located on a plate 22, 24 respectively, that is to say that the plate 22 connected to the pole less of the battery is the one that is under the upper side. The same goes for a module 18 represented symbolically. As can be seen, the terminals of the capacitors and modules must be connected each time to the two plates 22, 24. For a connection to be made with the top plate 22, the bottom plate 24 and the sheet 38 must have a pattern of corresponding holes to allow the passage, without contact, the connections. FIG. 3 shows that the upper plate 22 also has enlarged holes, as shown at 39 or 40, for connection of the connections with the lower plate 24 by means of screws 32 or 36. connections with the upper plate 22, it is enough instead of holes 42 or 44 relatively small which

  receive the appropriate screws 30 or 34.

  As indicated in FIGS. 1 and 2, bars 46, 48, in the form of a plate, are mounted on the modules by means of screws 50, 52, bars 46 covering five modules and bar 48 covering three modules. . The five modules, to which is hung the bar 46 belong for example to the power portion for the operation of a displacement motor while the bar 48 covers the modules for the power portion of a hoist motor. Bars 46, 48 carry extensions 53, 54 which lead to connection terminals 56, 58, which are connected mechanically,

  but electrically isolated from the heat sink 12.

  The extensions 52, 54 can also be flexibly made. The connection terminals are for example connected to the motor or the motor

lifting.

  The power part according to FIG. 3 differs from that of FIG. 2 in that, with the modules, nine of which are provided in total, three plate-shaped bars 60, 62 and 64 are connected to the upper side of the modules. modules as described above and have extensions 66, 68, 70 which lead to three terminals 72, 74, 76. The module shown is intended for a three-phase motor powered battery. Other parties

  are similar to those in Figure 2.

  FIG. 5 shows in perspective a switching circuit board 80 on which is housed all the components and parts serving to control, for example, power components according to FIGS. 1 to 4. For example, an electric motor is controlled by means of this called a half-bridge, and optionally operates as a bearing element or as a lowering element depending on existing current conditions. These different parts are not described in detail. On the opposite sides of the plate 80, there are support plates 82, 84 for making a suitable attachment, there are control interfaces 86 and two ring-shaped current sensors 88, 90. FIG. control panel 80 sectional view, as it is installed on a power portion, for example that of Figure 1. Also distinguishes the arrangement of the capacitors 14 and semiconductor modules 18 on the heat sink 12. In addition, the way in which the extension 54 of the bar 46 passes through the sensor 90 of

annular form.

  The connection of the various electrical or electronic components of the control board 80 with the semiconductor modules 18 is not represented, nor is

  the mechanical fixing of the plate 80.

  Let us also indicate that the negative plate 22 can also cover, in an isolated manner, the rail or rails

armature.

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Claims (12)

claims   Circuit arrangement for the operation of at least one battery-powered electric motor fitted to a industrial truck, having at least one capacitor (14, 16) and at least one semiconductor switch (18) arranged on a plate-shaped carrier member (12) and can be electrically connected to a control part, characterized in that at least one capacitor (14, 16) and a semiconductor switching module (18) are arranged on a carrier element (12) common and in that, above these electrical components and covering at least partially, are arranged two plates (22, 24) of electrically conductive material, slightly spaced apart from each other, and between which there is a thin insulating layer, one plate (22) connectable to the minus terminal and the other to the plus terminal of the battery, and in that the terminals of the electrical components are connected to each other. respectively to a plate (22, 24) by a connection directed to the plate arrangement, the lower plate (24) and the insulating layer (38) having penetrations for the passage of the connections to the upper plate (22). Circuit arrangement according to Claim 1, characterized in that at least one row of capacitors (14, 16) is arranged on the carrier element (12) and in that a plurality of semiconductor modules (18) are arranged   in a row parallel to the row of capacitors.   Circuit arrangement according to claim 2, characterized in that the battery connections (26, 28) on the plates (22, 24) are located at the ends   opposite of the row of capacitors.   4. Circuit arrangement according to one of   Claims 1 to 3, characterized in that the connection   motor is also made in the form of a plate (46, 48)   which extends over modules (18).   5. Circuit arrangement according to one of   Claims 1 to 4, characterized in that in the case   two electric motors fitted to a truck, the capacitors (14, 16) and the corresponding semiconductor modules (18) are placed together on the carrier element (12) and connected to the plate arrangement (20), all the capacitors (14, 18) being mounted in parallel.   Circuit arrangement according to claims 4   and 5, characterized in that the two motor connections are in the form of bar-shaped bars. plate (46, 48).   7. Circuit arrangement according to one of   Claims 1 to 6, characterized in that a sheet   insulation (38) is arranged between the plates (22, 24) in   conductive material of electricity.   8. Circuit arrangement according to one of   Claims 1 to 7, characterized in that in the plate   top plate (22) of the plate arrangement (20), a large surface elevation (24a) is formed which receives the lower plate (24).   9. Circuit arrangement according to one of   Claims 1 to 8, characterized in that the plate (22)   connected to the minus pole of the battery is arranged on the upper side.   10. Circuit arrangement according to one of   Claims 1 to 9, characterized in that a plate (80)   containing the control part is arranged on the plate outer or upper (22).   11. Circuit arrangement according to claim 10, characterized in that a current sensor (88, 90), preferably of annular shape, is arranged on the side of the plate (80) which is turned towards the power section. and in that an extension (53, 54) of the motor connection (46, 48) connected to the semiconductor modules (18) passes through the current sensor (88, 90) to join a connection terminal (58, 56).   Circuit arrangement according to one of Claims 1 to 11, characterized in that the element   carrier (12) is constructed as a heat sink.