CONVERTER MOTOR

Abstract

In a converter motor, the converter unit and the electric motor together form a mechatronic unit. The converter unit is located behind the electric motor and is thermally coupled with the rear bearing shield. The converter unit includes a through hole, through which the rear end of the motor shaft passes. A contactless position detector is located in the region of this through hole.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a shows a first view of an inventive electric motor with a converter unit, according to the invention;

FIG. 1 b shows a further view of the electric motor in FIG. 1a, according to the present invention;

FIG. 2 shows the electric motor in FIG. 1a, with the fan hood removed, according to the present invention;

FIG. 3 shows the motor in FIG. 1 without the fan wheel, according to the present invention;

FIG. 4 shows the motor in FIG. 1a without the converter unit, according to the present invention;

FIG. 5 shows an electric motor without the back wall or the converter unit, according to the present invention; and

FIG. 6 shows an inventive converter unit for the electric motor, according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 a and 1b show an inventive converter motor 1 with a motor housing 3, on which a converter unit 6 is located. Reference numeral 8 indicates a fan hood of the converter unit, which also includes a large number of openings in its back wall 8a, for ventilation.

The mains connection is plugged directly into converter unit 6. A socket (e.g., DESINA) is integrated in the base plate or cover 7 of converter (see FIG. 4). Plug 2 rests on motor 1 in a space-saving manner, thereby minimizing the amount of installation space required for the converter motor. The cable outlet direction of plug 2 may be adapted to the required conditions in any manner necessary by selecting the plug sleeve accordingly.

The unit composed of motor and converter unit may be designed with degree of protection IP 65. Since the converter unit has a closed housing, the only concern is to ensure that the system have a tight seal in the region of the winding termination, which may be attained, e.g., by installing an O ring on the circumference of the end face of the bearing plate of the motor.

FIG. 2 shows the converter motor in FIG. 1, with fan hood 8 removed. Reference number 23 indicates a fan wheel installed on the shaft, i.e., on end section 4a of the shaft. The fan wheel must serve its purpose regardless of the direction of rotation, which means the cover would be in the “slipstream” at least part of the time. The desired movement of air in the region of the converter cover, which is hidden by the fan wheel in FIG. 2, may be attained by the fact that the fan wheel includes axial through holes 24 near the shaft, which make possible a centrifugally outwardly oriented air flow between the cover (not shown) and the fan wheel.

Motor housing 3 includes ribs 3a for cooling.

FIG. 3 shows the converter motor in FIG. 2 with the fan wheel removed. In this figure it is clear that converter unit 6 includes a converter cover 7 that includes a through hole 14, through which motor shaft 4 extends. Reference numeral 5 indicates the terminals for the control signals.

FIG. 4 shows the converter motor in the previous figures, with the converter unit removed. Reference numeral 11 indicates the rear wall of motor housing 3, on which the converter unit is located. The inventive converter motor is equipped with a device for measuring the rotor position. Since, as mentioned above, the converter unit encloses the motor shaft, a sensor that detects the angle of rotation of motor shaft 4 in a contactless manner may be integrated in the converter unit.

A possible means of attaining the object of the present invention is to use a ring magnet 26 magnetized in an alternating manner, which serves as a signal transducer in this case. This ring magnet is mounted on the motor shaft and is located in through hole 14 of converter unit 6. Specifically, the signal transducer is a ring magnet that is magnetized in an alternating manner in the circumferential direction, is mounted on the shaft and is located in through hole 14 of converter unit 6. The magnetic field of signal transducer 26 is measured by two Hall sensors located at an angle of 90° (based on the pole pitch) of the magnet. The angle of rotation may be determined using the arctan function.

With the aid of this very robust and cost-favorable angular sensor, a field-oriented injection of the current and regulation of the rotational speed and position are made possible, thereby ensuring optimal, stable operation under all conditions, in contrast to methods that operate without sensors. This also applies, without restriction, when the motor is at a standstill and when it is being positioned. Due to the low costs associated with the inventive position measurement, sensorless control methods cannot compete, because they utilize a great deal of computing effort and result in inferior rotational speed regulation.

FIG. 5 shows a view into the interior of the electric motor, i.e., after the back wall of the electric motor—which is mounted on housing 3 and forms a single unit therewith—was removed. Reference numeral 12 in FIG. 4 indicates a motor-side counterplug for connection of the motor winding. In other words, the electrical connection of the converter unit with the motor winding is preferably a plug-in connection and is located in a through hole in converter base plate 16. As shown in FIG. 4, motor-side counterplug 12 is installed in back wall 11 and/or the rear bearing plate. This configuration also results in a further simplification of the overall design.

FIG. 6 shows an inventive converter unit 6. Reference numeral 14 indicates the through hole for passage of the shaft. This through hole is located in base plate 16 of converter unit 6. Reference numeral 15 indicates the plug for the converter output, which interacts with counterplug 12 of the electric motor shown in FIG. 4.

Converter unit 6 is therefore annular in shape, thereby enclosing motor shaft 4. It is installed on rear wall 11 (see FIG. 4) of the electric motor from behind. The desired low heat-transfer resistance between rear wall 11 and converter unit 6 is attained via flat surfaces of the back wall and base plate 16 of the converter. Heat transfer may be improved further by using heat conducting paste or a thermally conductive foil. The housing of the converter unit is formed in this case by base plate 16 and cover 7.

Furthermore, converter unit is located directly in the air flow of fan wheel 23 (see FIG. 2), which, as mentioned above, is preferably designed as fan wheel 23 installed on the motor shaft. Although the effect of this fan wheel is therefore dependent on the rotational speed, it is also equally effective in cooling the motor, because the motor losses (core losses)—which depend on the rotational speed—increase as the rotational speed increases. The cooling effect, which also increases as the rotational speed increases, therefore compensates for the increasing losses. The motor still delivers a usable stall torque even though there is no air flow when the motor is at a standstill. To increase the power at lower rotational speeds, a separately driven fan may be used.

As shown in FIG. 6, the inventive converter unit is divided into two zones, which are thermally insulated from each other. The power electronics, which absorb the temperature of the motor housing (e.g., up to 100° C.), are located on metallic base plate 16, which is screwed onto the motor. Cover 7, which is also preferably metallic and faces the fan, is thermally insulated from the base plate. The temperature-sensitive circuits (e.g., microprocessor, user interface, and the like) of converter unit 6 are thermally coupled internally to this cover. An intermediate piece 18 made of plastic is located between base plate 16 under cover 17; it provides the thermal insulation.

The cooling of the power electronics on converter unit 6 therefore takes place via the introduction of dissipation heat into motor housing 3 via rear wall 11. The entire surface of the motor is effective for cooling. The cooling effect of the fan may also be used primarily for the power electronics by providing the rear bearing plate or back wall 11 with as much surface area as possible, and by providing cooling ribs on the circumference. Cooling the cover 7 of the converter unit is less problematic, since relatively little dissipation heat is introduced here. Cover 7 may also be provided with cooling ribs, which extend into the air flow of the fan. A design of this type is suited in particular for connection with a separately driven fan.

Reference numeral 25 indicates a fastening screw, which is used to connect converter unit 6 with the motor. To this end, the four screws 25 shown are screwed into corresponding threaded bores 27 of the motor housing (see FIG. 4). Reference numeral 17 indicates a locking clamp for a mains plug.

In order to realize the “secure hold” functionality, converter unit 6 is advantageously equipped with an electronic start-up lock (without a relay), which reliably prevents the motor from starting up when the energy supply is switched on. When an operational voltage disconnection is not required, the start-up lock replaces the expensive mains contactor. In this case, the line fuse is sufficient.

The inventive converter motor is designed primarily to replace the previously common standard motor with the associated mains supply interface. The advantages of the inventive motor include energy savings resulting from the fact that the rotational speed is adaptable and that the magnetizing current may be reduced. In addition, the functionality may be expanded to include a variable rotational speed and direction of rotation, and the usual mains supply interfaces may be eliminated. For braking operation, active braking (DC braking) is possible in place of coasting to a standstill.

A start/stop operation with generator braking requires braking resistance—which would have to be provided separately, due to the considerable power loss, or the braking energy would have to be returned to the mains; this is possible, e.g., when the converter unit is designed as a matrix converter. Due to spacial limitations, it is assumed that direct-current braking or a comparable method, with which the braking energy in the motor winding is converted to heat, is a reasonable choice in combination with the inventive method, to limit the converter losses. When the circuit is designed accordingly, braking may also be carried out if there is a mains failure. Furthermore, the converter motor must be parametrized for the application, and expected values must be provided. The connection of the motor via a field bus continues to prevail from the related art.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the type described above.

While the invention has been illustrated and described as embodied in a converter motor, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

Claims

1. A converter motor, comprising an electric motor having a motor shaft and a back wall; and a converter unit for controlling said electric motor, said converter unit including a plurality of control components and being located on said electric motor, said converter unit having a housing located on said back wall of said electric motor, said converter unit also including a through region through which a rear end of said motor shaft of said electric motor passes.

2. A converter motor as defined in claim 1, wherein said converter unit encloses substantially an entire geometrical area of said motor shaft in a circumferential direction of said motor shaft.

3. A converter motor as defined in claim 1, wherein said converter unit has a substantially flat base plate which is in direct contact with said back wall of said electric motor.

4. A converter unit as defined in claim 1, wherein said converter unit includes a base plate which has a high coefficient of heat conductivity and is located directly on said back wall of said electric motor.

5. A converter unit as defined in claim 1, wherein said housing of said converter unit has an opening that extends toward said electric motor; further comprising a heat transfer element located in said opening and preloaded such that it is pressed against said back wall of said electric motor.

6. A converter unit as defined in claim 4; further comprising a cover which is thermally insulated from said base plate, said converter unit having temperature-sensitive components which are thermally coupled with said cover.

7. A converter unit as defined in claim 1, wherein said motor shaft has an end section, further comprising a fan wheel located on said end section of said motor shaft.

8. A converter unit as defined in claim 7, wherein said fan wheel includes a plurality of openings.

9. A converter unit as defined in claim 1, further comprising a signal transducer located on a section of said motor shaft that is guided through said converter unit.

10. A converter unit as defined in claim 9, wherein said signal transducer is configured as an annular element that is mounted on said motor shaft of said electric motor.

11. A converter unit as defined in claim 9, further comprising a fan wheel located on an end section of said motor shaft, said signal transducer being configured as an annular element that is integrated in a hub of said fan wheel.

12. A converter unit as defined in claim 1, further comprising a sensor element that determines a temperature of at least one section of an element selected from the group consisting of a base plate of said converter unit and a heat transfer element pressed against said back wall of said electric motor.

13. A converter unit as defined in claim 1; further comprising a signal transducer; and a sensor element for a contactless detection of an angular position of said motor shaft, said sensor element being positioned such that it is centered behind said motor shaft in said converter unit, while said signal transducer is located on an end of said motor shaft.

14. A converter unit as defined in claim 13, further comprising an encoder disk located on said motor shaft behind said converter unit.

15. A converter unit as defined in claim 1, wherein said converter unit is configured as an inverter supplyable with direct current.

16. A converter unit as defined in claim 1, further comprising a plug-in mains connection integrated in said converter unit.

17. A converter motor, comprising an electric motor having a motor shaft and a back wall; and a converter unit for controlling said electric motor, said converter unit including a plurality of control components and being located on said electric motor, said converter unit being located on said back wall of said electric motor, and said converter unit being thermally coupled with said electric motor.

18. A converter motor as defined in claim 17, wherein said converter unit encloses substantially an entire geometrical area of said motor shaft in a circumferential direction of said motor shaft.

19. A converter motor as defined in claim 17, wherein said converter unit has a substantially flat base plate which is in direct contact with said back wall of said electric motor.

20. A converter motor as defined in claim 17, wherein said converter unit includes a base plate which has a high coefficient of heat conductivity and is located directly on said back wall of said electric motor.

21. A converter motor as defined in claim 17, wherein said housing of said converter unit has an opening that extends toward said electric motor. further comprising a heat transfer element located in said opening and preloaded such that it is pressed against said back wall of said electric motor.

22. A converter motor as defined in claim 19; further comprising a cover which is thermally insulated from said base plate, said converter unit having temperature-sensitive components which are thermally coupled with said cover.

23. A converter motor as defined in claim 17, wherein said motor shaft has an end section, further comprising a fan wheel located on said end section of said motor shaft.

24. A converter motor as defined in claim 23, wherein said fan wheel includes a plurality of openings.

25. A converter motor as defined in claim 17, further comprising a signal transducer located on a section of said motor shaft that is guided through said converter unit.

26. A converter motor as defined in claim 25, wherein said signal transducer is configured as an annular element that is mounted on said motor shaft of said electric motor.

27. A converter motor as defined in claim 25, further comprising a fan wheel located on an end section of said motor shaft, said signal transducer being configured as an annular element that is integrated in a hub of said fan wheel.

28. A converter motor as defined in claim 17; further comprising a sensor element that determines a temperature of at least one section of an element selected from the group consisting of a base plate of said converter unit and a heat transfer element pressed against said back wall of said electric motor.

29. A converter motor as defined in claim 17; further comprising a signal transducer; and a sensor element for a contactless detection of an angular position of said motor shaft, said sensor element being positioned such that it is centered behind said motor shaft in said converter unit, while said signal transducer is located on an end of said motor shaft.

30. A converter motor as defined in claim 29, further comprising an encoder disk located on said motor shaft behind said converter unit.

31. A converter motor as defined in claim 17, wherein said converter unit is configured as an inverter supplyable with direct current.

32. A converter motor as defined in claim 17; further comprising a plug-in mains connection integrated in said converter unit.

33. A converter unit for controlling an electric motor with a plurality of control components, said converter unit including a base plate locatable on a back wall of a motor housing, and an opening through which a motor shaft of the electric motor is guidable.

34. A converter unit as defined in claim 33, further comprising a plug-in mains connection integrated in said converter unit.

35. A converter unit as defined in claim 33, wherein the converter unit is configured as an inverter supplyable with direct current.