Electric motor with rotary encoder

Abstract

The invention relates to an electric motor (1) comprising a drive shaft (5) carrying a rotor (2), a device for supplying and controlling the 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 encoder comprising a sensor (7, 7') arranged on said electronic board and an angle encoding element (6) arranged opposite the sensor on the drive shaft, said electronic board comprising power electronics (33) for controlling the windings and a unit (34) for calculating and controlling the phases of the windings.

Description

[Technical field]

[0001] The present disclosure relates to the field of control of electric motors, in particular electric motors driving wheels such as wheels of robotic manipulation devices, and relates to electric motors provided with rotary encoders. [Background technology]

[0002] The electric motor that drives the wheels may be a motor controlled by motor control electronics powered by a DC source, such as a battery. For the purpose of precisely controlling the rotation of the motor, it is useful to know the position and speed of rotation of the motor's rotor. Generally, a rotary encoder comprises a rotating part mounted on the shaft of the motor and a sensor to transmit this information back to the motor controller.

[0003] The encoder sensor is typically fixed to the motor and connected by wires to motor control electronics located within the motor. Summary of the Invention [Problem to be solved by the invention]

[0004] In particular in robotic manipulation devices, it is desirable to make the motor and its control electronics more compact, to make the operation of the assembly more reliable, and to simplify repairability of the assembly. To this end, the present disclosure proposes to incorporate a motor rotation encoder sensor into the electronics, which are then added onto the motor. [Means for solving the problem]

[0005] The present disclosure therefore proposes an electric motor comprising a motor shaft carrying a rotor, a device for supplying and controlling the winding phases of a stator of said motor on an electronic circuit board fixed to the motor, and one or more angular encoders, said angular encoder comprising a sensor arranged on said electronic circuit board and an angle encoding element arranged opposite said sensor on the motor shaft, said electronic circuit board comprising power electronics for controlling the windings and a unit for calculating and controlling the phases of the windings.

[0006] This makes it possible to create a block that is compact and can be easily installed, while at the same time allowing the substrate to be removed for possible repair.

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

[0008] According to a first embodiment, the motor shaft passes through the electronic circuit board. According to an alternative embodiment, the electronic circuit board faces the end of the shaft.

[0009] Advantageously, the electronic circuit board is arranged in a removable and replaceable flange fixed on the face of the motor casing, called the rear face, through which the motor shaft passes, the flange including a bottom provided with a hole through which the motor shaft passes and a border surrounding the outer periphery of the electronic circuit board, the sensor being arranged opposite the angle encoding element carried by the motor shaft.

[0010] The angle coding element is advantageously a multi-pole magnet and magnetic field sensor, which avoids dirt or dust from interfering with the measurement.

[0011] A rear cap can be secured to the flange, with the rear cap and the flange forming a housing enclosing a space for receiving the electronic circuit board, thus protecting the board and the motor shaft which are secured to the motor.

[0012] The flange may include a non-magnetic cylindrical wall having a common axis with the motor shaft and disposed between the multi-pole magnet and the one or more sensors to separate and seal the housing of the electronic circuit board.

[0013] The motor shaft can be extended by a segment that passes through an opening in the rear cap to create support for at least one complementary piece of equipment.

[0014] The complementary equipment may be an electromechanical brake including a disc and one or more calipers coupled to and controlled by the electronic circuit board, the calipers mounted on the rear cap of the block and the discs mounted on the through-segments.

[0015] The present disclosure also relates to an electronic circuit board for an electric motor as described above, including through holes for one or more angle encoder sensors disposed on an outer edge of the motor shaft and the bore.

[0016] The electronic circuit board may include power connection pins for the stator windings that are adapted to be connected to a connector that groups the stator power wires at the flange, thus allowing the board to be easily connected to the motor power cable.

[0017] The electronic circuit board may include communication components for communicating with a management system of a steering device in which the motor drives one or more wheels.

[0018] Through said communications components, the board can be programmed to provide an external computer with calculated speed information, motor position increments, and motor direction of rotation.

[0019] The present disclosure also relates to a rolling vehicle comprising at least a motor according to any one of the preceding claims and an electronic circuit board.

[0020] Finally, the present disclosure provides a method for assembling and calibrating a motor equipped with a board as described, comprising the steps of: - fixing the angle-encoding element on the motor shaft and fixing the substrate equipped with the sensor in its final mechanical position on the motor, the relative angular position of the magnet with respect to the sensor of the substrate being arbitrary and unknown; - forcing the rotor to rotate by applying a rotating magnetic field by controlling the stator of the motor simultaneously with the application of a defined three-phase voltage that creates a defined rotating field during a complete revolution; - measuring by means of a sensor the state of the magnetic field induced by the magnet during the forced rotation of the shaft and determining by means of a calculation unit the angular deviation between said state of the magnetic field measured by the sensor and the position given in the rotation of the motor by the field applied to the stator; Including, the deviation between said measured state and the given position is stored in a fixed memory in the board and constitutes calibration data for the motor / encoder / board assembly; Method, relating to.

[0021] Other features, details and advantages will become apparent upon reading the following detailed description and examining the accompanying drawings. [Brief description of the drawings]

[0022] [Figure 1] FIG. 2 is a schematic cross-sectional side view of one embodiment. [Diagram 2] FIG. 13 is a schematic cross-sectional side view of a complementary embodiment. [Diagram 3] FIG. 2 is a perspective view of a motor with an electronic circuit board mounted inside a flange. [Figure 4] 1 is a diagram of an example of a ring magnet. [Diagram 5] FIG. 1 is a diagram of a variation device of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Reference is now made to Figure 1, which shows diagrammatically 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 motors, of the brushless direct current motor type known under the abbreviation BLDC motor, are controlled by a converter and correspond to direct current motors.

[0024] The motor may be a brushless three-phase motor whose phases are powered by a power switching system with three MOSFET or IGBT power half-bridges independently controlled by a programmable computer in the device for powering and controlling the motor winding phases in the motor control electronics, as is known.

[0025] For the purpose of precisely controlling the rotation of the motor, it is useful to know the position and speed of rotation of the rotor of the motor. Typically, a rotational encoder is mounted on the shaft of the motor and returns this information to the motor control device. In the example of the present disclosure, particularly in Figs. 1, 2 and 5, said encoder is created by the integration of a magnetic sensor 7 directly on the motor control electronics board 3, opposite an angle encoding element 6, here consisting of an annular multipole magnet, for example a magnet with 12 pairs of poles 6a, 6b as shown in Fig. 4, mounted on the motor shaft 5, opposite a sensor that allows obtaining information about the speed and angular position of the motor directly by the electronics of the control drive device.

[0026] According to Figures 1 and 2, the substrate 3 comprises an opening through which the shaft 5 passes and the sensor is present at the outer edge of said opening, and according to Figure 5 the substrate 3' is arranged opposite the end of the shaft and the sensor 7' is arranged on the so-called bottom side of the substrate, opposite the angle encoding element 6.

[0027] The electronic circuit board 3 is mounted in a flange 4, according to the example, at right angles to the axis of the motor shaft. The flange is arranged on the face 21a of the motor casing 21 at the axial end, called the rear end, of the motor and creates an interface between the rear end of the motor and the electronic circuit board. The flange comprises a bottom wall 41, which is fixed on the rear wall 21a of the motor, and a border part 42, the flange forming a receptacle in which the electronic circuit board 3 is fixed firmly and positioned relative to the motor shaft.

[0028] The sensor 7 of the angle encoder, here a magnetic field sensor, for example a Hall effect sensor, is arranged on the electronic circuit board opposite an annular multi-pole magnet 6 which is itself arranged on the motor shaft 5 which passes through the board.

[0029] The sensors can be of the magnetic field sensor type, in particular Hall effect sensors. Three sensors distributed at 120° around a multi-pole magnet on the motor shaft as shown in Figure 3 allow sufficient accuracy of the operation of the motor as a means for driving the wheels of a steering device.

[0030] Solutions using optical encoders, including optical sensors and optical encoder wheels, or solutions using toothed encoder wheels and magnetic sensors are also conceivable in the context of the present disclosure.

[0031] The disclosed device has the advantage of combining all of the electronic, control and sensor functions of the encoder in a single mechanical assembly to form a motor control block. The elements of this control block can be assembled separately from the motor, making the motor control block a modular functional block that will be directly mounted on the motor, for example at the end of a production line. Several motor control block versions can be proposed for the same motor, and easy replacement of said control block facilitates maintenance of the device.

[0032] According to the example of Figure 1, the electric phase cables of the motor are mounted on the flange and connected via a connector 43 which receives the connection pins 32 coming from the electronic circuit board to facilitate installation and replacement of the motor control block or the electronic circuit board. These cables can be connected directly to the electronic circuit board 3 as shown in Figure 2.

[0033] FIG. 2 shows an embodiment in which a rear cap 8 is fixed to the flange, said rear cap and flange forming a housing enclosing a space for receiving an electronic circuit board, protecting said electronic circuit board from external attack.

[0034] It is also possible to provide a non-magnetic cylindrical wall 9 having a common axis with the motor shaft 5, disposed between the multi-pole magnet and the one or more sensors, which makes it possible to seal the housing of the electronic circuit board and to provide even better protection for the electronic circuit board.

[0035] Further according to the variant of FIG. 2, the motor shaft can be extended by a segment 5a which passes through an opening in the rear cap 8 to create a support for at least one complementary piece of equipment, which can be an electromechanical brake including a disk 11 connected and controlled by an electronic circuit board and one or more calipers 10.

[0036] In this example, the caliper is mounted on the rear cap 8 of the control block and the disk is mounted on said through segment 5a.

[0037] FIG. 3 shows the mounting of an electronic circuit board 3 in a flange 4 at the rear of the motor, this board being fixed, for example by means of screws 38, on spacers 43 of the flange.

[0038] The substrate includes a hole 31 allowing a multi-pole magnet 6 to pass therethrough, and sensors 7a, 7b, 7c are arranged on the outer edge of the hole, around said magnet.

[0039] The electronic circuit board further comprises power electronics 33 for controlling the phases of the motor, a computing unit 34 such as a microprocessor or microcontroller associated with a fixed memory 35, for example of EEPROM type that can be updated, including a program for controlling the motor and calibration data, as well as a random access memory 36. The board may comprise a communication component 37, for example a component for managing a field bus, for example of CAN or Ethernet type, or even a wireless link such as Wi-Fi, Bluetooth, ZigBee or even 5G, which is connected to the computing unit and to an antenna not shown, or a wired link component that couples the electronic circuit board with a control computer on a rotating device, such as a steering device including one or more motors of the present disclosure, driving the wheel of said rotating device, allowing the electronic circuit board to communicate with a remote or embedded management system of said rotating device.

[0040] According to one important aspect, the illustrated device does not include mechanical angular positioning between the motor's multi-pole magnets and windings. Once the electronic circuit board is assembled onto the motor, a self-calibration procedure is performed to know the angular position of the rotor and control the phase of the stator relative to the rotor, which is important for maximizing the motor starting torque.

[0041] The self-calibration procedure is performed after pairing of the sensor electronics assembly with a motor carrying on its axis a means for providing position information, a multi-pole magnet, an encoder wheel, etc., at the output of the production line or during the first commissioning of the product.

[0042] In this procedure, After the motor and electronic circuit board are assembled, - The angle coding element 6 is fixed, for example by gluing, onto the motor shaft and the substrate 3 is placed in its final mechanical position on the motor. After these operations, the relative angular position of the coding element, e.g. a multi-pole magnet, with respect to the sensor 7 of the substrate is arbitrary and unknown.

[0043] The rotor 2 is then caused to rotate by applying a magnetic field by controlling the stator 20 of the motor simultaneously with the application of defined three-phase voltages which create a defined rotating field, the position of the motor being thus given during one complete revolution.

[0044] During the forced rotation of the shaft, the sensor 7 measures the state of the magnetic field induced by the magnet and the calculation unit 34 determines the angular deviation between said state measured by the sensor and a given position in the rotation of the motor due to the field applied to the stator.

[0045] The deviation between the measured state and the given position is stored in a fixed memory 35 within the board and constitutes the calibration data for the motor / encoder / board assembly.

[0046] The procedure is fully automated, making it possible to overcome the variability associated with the mechanical assembly by the determination of parameters allowing the shaping and normalization of the signals received by one or more sensors.

[0047] The procedure then allows the information from the sensor to be correlated with the position of the rotor of the motor, and allows the information from this sensor to be used for the generation of a rotating magnetic field that is used to control the motor.

[0048] According to the example of Fig. 3, the encoder device comprises three logical sensors 7a, 7b, 7c offset by 120° opposite an annular multi-pole magnet with 12 pairs of poles resulting in 6 recombination states, i.e. a relative position of 72° with respect to the basic control of the motor. However, the number of pole pairs can be higher for higher precision. To obtain higher precision, two analog sensors 71a, 71b arranged at 90° in sine / cosine can be added opposite the multi-pole magnet, or the number of logical sensors can be increased. The placement of the sensors directly on the electronic circuit board avoids having electrical coupling cables between the sensors and said board, making the installation more robust, in particular against vibrations.

[0049] In applications requiring significant safety operation, it is also possible to use a safety encoder with additional redundant sensors in parallel, sensors providing redundant measurements, or a safety controller.

[0050] If a zero rotation point of the motor is desired, a sensor, for example an additional magnetic sensor, can be disposed opposite a pin or groove on the metal shaft.

[0051] The invention is not limited to the illustrated examples, in particular the electronic circuit board can be divided into modules for better repairability. [Explanation of symbols]

[0052] 1 Electric motor 2 Rotors 3, 3´ Motor control electronic circuit board 4 Flanges 5 Motor shaft 5a segment, through segment 6 Angle encoding element, annular multipole magnet 6a, 6b pole 7, 7´ Magnetic Sensor 7a, 7b, 7c logic sensor 8 Rear Cap 9 Non-magnetic cylindrical wall 10 Caliper, electronic mechanical brake 11 disc, electromechanical brake 12 Connected 20 windings, stator 21 Motor casing 21a (motor casing) face, (motor) rear wall 31 Hole 32 connection pins 33 Power Electronics 34 Computational Units 35 Fixed Memory 36 Random Access Memory 37 Communication Components 38 Screw 41 (flange) bottom wall 42 (Flange) boundary 43 Connectors, spacers 71a, 71b Analog sensor

Claims

1. 1. An electric motor (1) comprising a motor shaft (5) carrying a rotor (2), a device for supplying and controlling winding phases (20) of a stator of the motor on an electronic circuit board (3, 3') fixed to the motor, and one or more angle encoders, characterized in that the angle encoder comprises a sensor (7, 7') arranged on the electronic circuit board and an angle encoding element (6) arranged opposite the sensor on the motor shaft, and that the electronic circuit board comprises power electronics (33) for controlling the windings and a unit (34) for calculating and controlling the phases of the windings.

2. 2. An electric motor as claimed in claim 1, wherein the motor shaft passes through the electronic circuit board (3).

3. 3. An electric motor according to claim 1 or 2, wherein the electronic circuit board is arranged in a removable and replaceable flange (4) fixed on a face (21a) of the motor casing (21), referred to as the rear face, through which the motor shaft (5) passes, the flange comprising a bottom part (41) provided with a hole through which the motor shaft (5) passes and a border part (42) surrounding the outer periphery of the electronic circuit board, the sensor being arranged opposite the angle coding element (6) carried by the motor shaft (5).

4. 4. Electric motor according to claim 1, 2 or 3, characterized in that the angle-encoding element (6) is a multi-electromagnet and magnetic field sensor (7, 7').

5. 5. An electric motor according to claim 1, further comprising a rear cap (8) fixed to the flange, the rear cap and the flange forming a housing (4, 8) enclosing a space for receiving the electronic circuit board.

6. 6. An electric motor according to claim 1, wherein the flange comprises a non-magnetic cylindrical wall (9) having a common axis with the motor shaft (5) and disposed between the multi-pole magnet and one or more of the sensors to separate and seal the housing of the electronic circuit board.

7. 7. Electric motor according to any one of claims 1 to 6, wherein the motor shaft (5) is extended by a segment (5a) which passes through an opening in the rear cap (8) to create a support for at least one complementary equipment.

8. 8. Electric motor according to claim 7, wherein the complementary equipment is an electromechanical brake (10, 11) including a disk (11) connected (12) and controlled by the electronic circuit board and one or more calipers (10), the calipers being mounted on the rear cap (8) of the block and the disks being mounted on the through-segments (5a).

9. 9. An electronic circuit board for an electric motor according to claim 1, characterized in that it comprises a hole for the passage of the motor shaft and one or more angle encoder sensors arranged on an outer edge of the hole.

10. 10. The electronic circuit board of claim 9, comprising pins (32) for connecting a power supply for the windings of the stator, adapted to be connected to a connector (43) that groups together the power supply wires of the stator at the flange.

11. 11. An electronic circuit board according to claim 9 or 10, comprising a communication component (37) for communicating with a management system of a steering device, the motor driving one or more wheels.

12. 12. The electronic circuit board of claim 11, wherein the board is programmed to provide speed information, motor position increments, and motor direction calculations to an external computer through the communications component.

13. A rolling vehicle comprising at least one electric motor according to any one of claims 1 to 8 and an electronic circuit board 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 board according to any one of claims 9 to 12, comprising the steps of: Fixing the angle coding element (6) on the motor shaft (5) and fixing the substrate (3) equipped with the sensor (7) in its final mechanical position on the motor, the relative angular position of the magnet (6) with respect to the sensor (7) of the substrate being arbitrary and unknown; b. forcing the rotor (2) to rotate by applying a rotating magnetic field by controlling the stator (20) of the motor simultaneously with the application of a defined three-phase voltage that generates a defined rotating field during a complete revolution; c) measuring with the sensor (7) the state of the magnetic field induced by the magnet during the forced rotation of the shaft and determining with the calculation unit (34) the angular deviation between the state of the magnetic field measured by the sensor and the position imparted in the rotation of the motor by the field applied to the stator; Including, the deviation between the measured state and the given position is stored in a fixed memory within the board and constitutes calibration data for the motor / encoder / board assembly.

Images