Electric motor with rotary encoder

Abstract

The invention relates to an electric motor (1) including a drive shaft (5) carrying a rotor (2), a device for powering and controlling winding phases (20) of a stator of said motor on an electronic board (3, 3') fixed to the motor, and one or more angle encoders, said angle encoders including sensors (7, 7') positioned on said electronic board and an angular encoding element (6) disposed facing the sensors on the drive shaft, and said electronic board includes power electronics (33) for controlling said windings and a unit (34) for computing and controlling the phase of said windings.

Description

ELECTRIC MOTOR WITH ROTATION ENCODER technical field

[0001] This disclosure falls within the domain of electric motor control, particularly electric motors for driving wheels such as wheels of robotic handling devices, and concerns an electric motor equipped with a rotation encoder. Previous technique

[0002] Electric wheel drive motors can be motors controlled by motor control electronics powered by a DC power source such as a battery. For precise control of the motor's rotation, it is useful to know the position and rotational speed of the motor's rotor. Typically, a rotation encoder consists of a rotating part mounted on the motor shaft and a sensor to send this information back to the motor control unit.

[0003] The encoder sensor is usually fixed to the motor and connected by wire to the motor control electronics located in the motor. Summary

[0004] Particularly for robotic handling devices, it is desirable to make the motor and its control electronics more compact, to improve the reliability of the entire system, and to simplify its repairability. This disclosure proposes to achieve this by integrating motor rotation encoder sensors into the electronics, which are then mounted on the motor.

[0005] Thus, this disclosure proposes an electric motor comprising a motor shaft carrying a rotor, a device for powering and controlling the winding phases of a stator of said motor on an electronic board fixed to the motor, and one or more angular encoders, for which said angular encoders comprise sensors positioned on said electronic board and an angular encoding element disposed opposite the sensors on the motor shaft, and for which said electronic board comprises power electronics of control of said windings and a unit for calculating and controlling the phase of said windings.

[0006] This allows for a compact and easily implantable block while still allowing the board to be disassembled for possible repair.

[0007] The features described in the following paragraphs may optionally be implemented, independently of each other or in combination with each other:

[0008] In a first embodiment, the electronic board is traversed by the motor shaft. In an alternative embodiment, the electronic board is positioned opposite one end of the shaft.

[0009] Advantageously, the electronic board is positioned in a removable and replaceable flange, fixed on one face of an engine casing called the rear face, through which the said engine shaft passes, the said flange having a base with a hole through which the said engine shaft passes and a border surrounding the perimeter of the electronic board, the said sensors being located opposite the said angular encoding element carried by the said engine shaft.

[0010] The angular encoding element is advantageously a multipolar magnet and the sensors are magnetic field sensors, which prevents dust or dirt from interfering with the measurements.

[0011] A rear cover can be attached to the flange, the rear cover and flange forming a housing that encloses a space for the electronic board. This protects both the board, which is attached to the motor, and the motor shaft.

[0012] The flange may include a non-magnetic cylindrical wall with a common axis with the motor shaft, positioned between the multi-pole magnet and the sensor(s) so as to separate and seal the housing of said electronic board.

[0013] The drive shaft can be extended by a segment passing through an opening in the rear hood to provide support for at least one additional piece of equipment.

[0014] The said additional equipment may be an electromechanical brake comprising a disc and one or more calipers connected and controlled by the electronic board, the said calipers being mounted on the rear cover of the block, the said disc being mounted on the said through segment.

[0015] This disclosure further relates to an electronic board for an electric motor as described above which includes a hole for the passage of said motor shaft and one or more angular encoder sensors disposed at the periphery of said hole.

[0016] The electronic board may include power supply pins for the stator windings, designed to connect to a connector that groups the stator power wires at the flange. This allows for easy connection of the board to the motor's power cables.

[0017] The electronic card may include a communication component with a management system of a handling device whose motor drives one or more wheels.

[0018] The card can be programmed to provide an external computer with speed information, engine position increment calculations and engine rotation direction through said communication component.

[0019] This disclosure also relates to a rolling machine comprising at least one engine and an electronic board according to any one of the claims as described above.

[0020] This disclosure finally relates to a method for assembling and calibrating a motor equipped with a circuit board as described, which includes, after assembly of the motor and assembly of the electronic circuit board: - a fixing of the angular encoding element on the motor shaft, a fixing of the board equipped with the sensors in its final mechanical position on the motor, the relative angular position of the magnet with respect to the sensors on the board being arbitrary and unknown, - a forced rotation of the rotor by applying a rotating magnetic field by driving the motor stator with the application of a defined three-phase voltage producing a defined rotating field for one complete revolution, - a measurement by means of the sensors of the states of the magnetic field caused by the magnet during the forced rotation of the axis, and a determination by the calculation unit of the angular deviation between said states of the magnetic field measured by the sensors and the position imposed during the rotation of the motor by the field applied to the stator; the deviations between said measured states and said imposed position being stored in permanent memory in the card and constitute the calibration data for a motor encoder card assembly. Brief description of the drawings

[0021] Other features, details, and advantages will become apparent upon reading the detailed description below and analyzing the attached drawings, on which:

[0022] [Fig. 1] shows a schematic side view in cross-section of one embodiment;

[0023] [Fig. 2] shows a schematic side view in cross-section according to a complementary embodiment.

[0024] [Fig. 3] shows a perspective view of an engine equipped with an electronic board in a flange;

[0025] [Fig. 4] shows an example of a ring magnet;

[0026] [Fig. 5] shows a variant of the device of the present disclosure. Description of the implementation methods

[0027] Reference is now made to Figure 1, which schematically represents, in longitudinal section, an electric motor 1 comprising a rotor 2 on a motor shaft 5 and a stator whose windings 20 are powered by a control device with electronic switches. Such a motor, a type of brushless direct current motor (BLDC), is driven by a converter and is considered equivalent to a DC motor.

[0028] The motor can be, in a known manner, a three-phase brushless motor whose phases are powered by a power switching system with three MOSFET or IGBT-controlled power half-bridges. independently by a programmable computer of a power supply and control device of motor winding phases in a motor control electronics.

[0029] For precise control of motor rotation, it is useful to know the position and rotational speed of the motor rotor. Generally, a rotation encoder is mounted on the motor shaft to send this information back to the motor control unit. In the example presented here, particularly in Figures 1, 2, and 5, the encoder is implemented by integrating magnetic sensors 7 directly onto a motor control electronic board 3 opposite an angular encoding element 6. This element consists of a ring-shaped multipolar magnet, for example, a twelve-pole-pair magnet 6a, 6b as shown in Figure 4, mounted on the motor shaft 5 opposite the sensors. This allows the motor's speed and angular position information to be obtained directly by the control electronics.

[0030] According to figures 1 and 2, card 3 has an opening to be crossed by the tree 5, the sensors being on the periphery of the opening, and according to figure 5, card 3' is located opposite one end of the tree, the sensors 7' being located on a so-called lower face of the card opposite the angular encoding element 6.

[0031] The electronic board 3 is, as shown in this example, mounted in a flange 4 perpendicular to an axis of the motor shaft. The flange is positioned on a face 21a of a motor housing 21 at an axial end, referred to as the rear end, of the motor and provides an interface between the rear end of the motor and the electronic board. The flange comprises a bottom wall 41 fixed to a rear wall 21a of the motor and a rim 44, the flange forming a receptacle in which the electronic board 3 is securely fixed and positioned relative to the motor shaft.

[0032] The sensors 7 of the angular encoders are here magnetic field sensors such as Hall effect sensors for example and are positioned on said electronic board opposite the annular multipolar magnet 6 itself positioned on the motor shaft 5 passing through said board.

[0033] The sensors are magnetic field sensors and can include Hall effect sensors. Three sensors are distributed at 120° around The multipolar magnet on the motor shaft as shown in Figure 3 allows sufficient precision for the motor to operate as a means of driving a wheel of a handling device.

[0034] A solution with optical encoders including optical sensors and an optical encoder wheel can also be considered within the framework of this disclosure or a solution with a toothed encoder wheel and magnetic sensors.

[0035] The device described in this disclosure has the advantage of integrating all the electronic functions, control, and sensors of the encoder into a single mechanical assembly forming a motor control unit. The components of this control unit can be assembled separately from the motor, making the motor control unit a modular functional unit that can be directly mounted on the motor at the end of the production line, for example. Several versions of the motor control unit can be offered for the same motor, and the easy replacement of the control unit simplifies maintenance of the device.

[0036] As shown in Figure 1, the motor's electrical phase cables are connected via a connector 43 mounted on the flange, which receives contact pins 32 from the electronic board to facilitate the mounting and replacement of the motor control unit or the electronic board. These cables can be connected directly to the electronic board 3 as shown in Figure 2.

[0037] Figure 2 represents an embodiment in which a rear cover 8 is fixed to the flange, this rear cover and the flange forming a housing enclosing a space for receiving said electronic card, thus protecting it from external aggressions.

[0038] It may also be provided that a non-magnetic cylindrical wall 9 with a common axis with the motor shaft 5 is disposed between the multi-pole magnet and the sensor(s), which makes it possible to seal the housing of said electronic board and to protect it even better.

[0039] According to the variant shown in Figure 2, the drive shaft can be extended by a segment 5a passing through an opening in the rear hood 8 to provide support for at least one additional piece of equipment, which may be a brake. electromechanical comprising a disc 11 and one or more calipers 10 connected and controlled by the electronic board.

[0040] In this example, the calipers are mounted on the rear cover 8 of the control block and the disc is mounted on said through segment 5a.

[0041] Figure 3 shows the mounting of the electronic board 3 in the flange 4 at the rear of the motor, this board being fixed for example on spacers 43 of the flange by screws 38.

[0042] The card has a hole 31 to allow the multipolar magnet 6 to pass through, and the sensors 7a, 7b, 7c are arranged around said magnet at the periphery of the hole.

[0043] The electronic board also includes power electronics 33 and a computing unit 34 such as a microprocessor or a microcontroller, associated with a permanent memory 35 for example of the EEPROM type so that it can be updated, containing the motor control program and calibration data and a random access memory 36, for controlling the motor phases.The card may include a communication component 37, for example a CAN or Ethernet type fieldbus management component, or a radio link such as Wifi, Bluetooth, Zigbee, or even 5G connected to the computing unit and an antenna not shown, or a wired link component connecting the electronic card with a controller computer on rolling stock such as a handling device comprising one or more motors of this disclosure to drive wheels of said equipment to enable the electronic card to communicate with a remote or on-board management system of said rolling stock.

[0044] Importantly, the device as shown does not include any mechanical adjustment of the angular position between the multipolar magnet and the motor windings. A self-calibration procedure is performed once the electronic board is mounted on the motor to determine the angular position of the rotor and control the stator phases relative to the rotor, which is crucial for maximizing the motor's starting torque.

[0045] The self-calibration procedure is carried out either at the end of the production line or during the initial commissioning of the product, following pairing. of the electronic sensor assembly and the motor supporting on its axis the means giving the position information, multipolar magnet, encoder wheel or other.

[0046] For this procedure:

[0047] After assembly of the motor and assembly of the electronic board:

[0048] - The angular encoding element 6 is fixed to the motor shaft, for example by gluing, and the board 3 is placed in its final mechanical position on the motor. After these operations, the relative angular position of the encoding element, for example a multipolar magnet, with respect to the sensors 7 of the board is arbitrary and unknown.

[0049] Next, the rotor 2 is set in rotation by applying a magnetic field by driving the stator 20 of the motor with the application of a defined three-phase voltage producing a defined rotating field and the position of the motor is thus imposed for 1 complete revolution;

[0050] During the forced rotation of the shaft, the sensors 7 measure the states of the magnetic field caused by the magnet, and the calculation unit 34 determines the angular deviation between said states measured by the sensors and the position imposed during the rotation of the motor by the field applied to the stator;

[0051] The differences between the said measured states and the said imposed position are stored in permanent memory (35) in the card and constitute the calibration data for a motor encoder card assembly.

[0052] The procedure is fully automated and eliminates variations related to mechanical assembly by determining the parameters that allow shaping or normalizing the signal received by the sensor(s).

[0053] The procedure then allows the information from the sensor to be matched with the position of the motor rotor, enabling the information from this sensor to be used to generate the rotating magnetic field used to control the motor.

[0054] According to the example in Figure 3, the encoder device comprises three logic sensors 7a, 7b, 7c offset by 120° relative to the annular multipolar magnet with 12 pole pairs, resulting in six recombining states, or a relative position of 72° for basic motor control. The number of pole pairs can However, a larger sensor may be needed for greater accuracy. To achieve greater accuracy, two analog sensors 71a and 71b arranged at 90° in a sine / cosine configuration can be added opposite the multipolar magnet, or the number of logic sensors can be increased. Positioning the sensors directly on the electronic board eliminates the need for electrical cables between them and the board, and makes the assembly more robust against vibrations.

[0055] For applications requiring high operational safety, it is also possible to use additional redundant sensors side by side, sensors providing redundant measurements, or a safety encoder with a safety controller.

[0056] In a case where a zero point of motor rotation is desirable, a sensor, for example an additional magnetic sensor, can be positioned facing a pin or groove on the metal shaft.

[0057] The invention is not limited to the examples shown and in particular the electronic board can be subdivided into modules for better repairability.

Claims

DEMANDS

1. Electric motor (1) comprising a motor shaft (5) carrying a rotor (2), a winding phase supply and control device (20) of a stator of said motor on an electronic card (3, 3') fixed to the motor and one or more angular encoders, characterized in that said angular encoders comprise sensors (7, 7') positioned on said electronic card and an angular encoding element (6) disposed opposite the sensors on the motor shaft, and in that said electronic card comprises power electronics (33) for controlling said windings and a unit (34) for calculating and controlling the phase of said windings.

2. Electric motor according to claim 1 wherein the electronic board (3) is traversed by the motor shaft.

3. Electric motor according to claim 1 or 2 wherein the electronic board is positioned in a removable and replaceable flange (4), fixed on a face (21a) of a motor housing (21) referred to as the rear face, through which is passed said motor shaft (5), said flange having a bottom (41) provided with a hole through which is passed said motor shaft (5) and a rim (42) surrounding the perimeter of the electronic board, said sensors being located opposite said angular encoding element (6) carried by said motor shaft (5).

4. Electric motor according to claim 1, 2 or 3 wherein the angular encoding element(6) is a multipolar magnet and the sensors (7, 7') are magnetic field sensors.

5. Electric motor according to any one of the preceding claims comprising a rear cover (8) fixed to the flange, the rear cover and the flange forming a housing (4, 8) enclosing a space for receiving said electronic card.

6. Electric motor according to any one of the preceding claims wherein the flange comprises a non-magnetic cylindrical wall (9) having a common axis with the motor shaft (5) disposed between the multi-pole magnet and the sensor(s) so as to separate and seal the housing of said electronic board.

7. Electric motor according to any one of the preceding claims wherein the motor shaft (5) is extended by a segment (5a) passing through an opening in the rear hood (8) to provide a support for at least one additional piece of equipment.

8. Electric motor according to claim 7 wherein said additional equipment is an electromechanical brake (10, 11) comprising a disc (11) and one or more calipers (10) connected (12) and controlled by the electronic board, said calipers being mounted on the rear cover (8) of the block, said disc being mounted on said through segment (5a).

9. Electronic card for an electric motor according to any one of the preceding claims characterized in that it comprises a hole for the passage of said motor shaft and one or more angular encoder sensors disposed at the periphery of said hole.

10. Electronic card according to claim 9 comprising pins (32) for powering the stator windings adapted to connect to a connector (43) grouping the stator power wires at the flange.

11. Electronic card according to claim 9 or 10 comprising a communication component (37) with a management system of a handling device of which said motor drives one or more wheels.

12. Electronic card according to claim 11 wherein the card is programmed to provide an external computer with speed information, calculations of engine position increments and direction of engine rotation through said communication component.

13. Rolling machine comprising at least one electric motor according to any one of claims 1 to 8 and an electronic card according to any one of claims 9 to 12.

14. A method for assembling and calibrating an electric motor according to any one of claims 1 to 8 equipped with a circuit board according to any one of claims 9 to 12, characterized in that it comprises, after assembly of the motor and assembly of the electronic circuit board: a. - fixing the angular encoding element (6) on the motor shaft (5), fixing the card (3) equipped with the sensors (7) in its final mechanical position on the motor, the relative angular position of the magnet (6) with respect to the sensors (7) of the card being arbitrary and unknown, b. a forced rotation of the rotor (2) by applying a rotating magnetic field by driving the stator (20) of the motor with the application of a defined three-phase voltage producing a defined rotating field during one complete revolution, c. a measurement by means of the sensors (7) of the states of the magnetic field caused by the magnet during the forced rotation of the shaft, and a determination by the calculation unit (34) of the angular deviation between said states of the magnetic field measured by the sensors and the position imposed during the rotation of the motor by the field applied to the stator; The differences between the said measured states and the said imposed position are stored in permanent memory in the card and constitute the calibration data for a motor encoder card assembly.

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