Motor control system with electronic safety braking

Abstract

The invention relates to a motor control system for an electric vehicle equipped with a brushless DC motor (1) having at least three phases. An electronic system for controlling said motor comprises a main power device (4) supplying power to a power half-bridge (2a, 2b, 2c) provided with an upper arm fitted with a first electronic switch (21a, 21b, 21c) and a lower arm fitted with a second electronic switch (22a, 22b, 22c) for supplying power to said phases of the motor. The control system further comprises a programmable computer (3) for controlling said first and second electronic switches by means of an output (3a) for controlling said electronic switches to implement at least a first driving mode of the motor according to a sequential switching control of the switches for generating a rotating electric field that ensures the rotation of the motor, and a second freewheeling mode in which the electronic switches of the power half-bridge are open. The system comprises a safety circuit suitable for generating an emergency braking mode and provided with a third electronic switch (9a, 9b, 9c) for short-circuiting the lower arm of the half-bridge in parallel with said second electronic switch (22a, 22b, 22c). The third electronic switch is controlled by an additional switching circuit (7) provided with a channel (7a) for detecting a break in the main power supply device (4) and / or a control channel (7b) coming from said programmable computer and suitable for closing said third switch to perform said emergency braking. The additional switching circuit is powered by a secondary power supply device (8).

Description

[Technical field]

[0001] The present invention relates to the field of electric vehicles or systems, such as motorized trucks that are autonomous or guided by an external control system, such as industrial trucks for automated warehouses. [Background technology]

[0002] It is known to manufacture autonomous electric vehicles, such as mobile robots that navigate a premises, such as an automated warehouse, to load and unload cargo, or to perform tasks, such as, for example, cleaning floors.

[0003] Such a vehicle has one or more electric motors for driving the wheels of the vehicle, an on-board computer for managing the operation of the motors, power batteries for the motors or powered rails in the case of a track on rails, and optionally a board for communicating with a remote control center which provides movement instructions for the vehicle to the on-board computer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] EP3618259A1 Summary of the Invention [Problem to be solved by the invention]

[0005] Safe operation of these vehicles requires a permanent ability to brake them even if power to one or more motors is lost, and it is known to fit these vehicles with mechanical emergency braking devices or electromagnetic brakes, which are cumbersome and have wearing parts.

[0006] US Patent No. 5,399,633 relates to a device in which the switches of the lower half bridge are shorted using a voltage loss detection circuit and an emergency power supply. This device is complex and does not allow for sustained or controlled braking during the freewheeling phase. [Means for solving the problem]

[0007] In view of the prior art, the present application provides a motorized control system for an electric motor of a mobile electric vehicle provided with an electric braking device for use upon loss of power to the motor's controller, which device can also be used as a controlled braking device during a freewheel phase.

[0008] To this end, the present disclosure provides a motorisation control system for a mobile electric vehicle comprising at least a three-phase brushless DC motor and an electronic control system for controlling said motor, the electronic control system comprising a main power supply device supplying power to said phases of the motor and supplying power to a power half-bridge provided with an upper arm on which a first electronic switch is mounted and a lower arm on which a second electronic switch is mounted, the control system controlling said first and second electronic switches by means of control outputs for said electronic switches to generate at least a first drive mode of the motor based on sequential switching control of the switches for generating a rotating electric field which rotates the motor, and a second freewheel mode in which the electronic switches of the power half-bridge are open. and a programmable computer for controlling a second electronic switch, the motorised control system further comprising a safety circuit designed to generate an emergency braking mode FS and provided with a third electronic switch for shorting a lower arm of a half-bridge in parallel with the second electronic switch, the third electronic switch being provided with a detection channel for detecting interruption of a main power device and / or a control channel from the programmable computer and controlled by an additional switching circuit designed to close the third switch to generate the emergency braking, the additional switching circuit being powered by a secondary power device.

[0009] Advantageously, the additional switching circuit comprises an inhibit output to the control outputs for the first and second switches to force the first and second switches into an open position when the third switch is closed.

[0010] Advantageously, the secondary power supply device is generated by an energy storage unit of a capacitor or supercapacitor.

[0011] According to complementary or separate embodiments, the system is configured to provide three operating modes, a first mode including powering the motor to provide traction to the vehicle, in a second mode the motor is in a freewheeling condition, and in a third mode the motor is electrically braked.

[0012] To this end, a motorized control system for a mobile electric vehicle, the motorized control system comprising a computer including a configuration programming mode comprising a traction configuration T, in which the computer controls the first and second electronic switches based on said sequential control, a freewheel configuration RL, in which the computer controls the first and second electronic switches to be open, and a motor braking configuration F, in which the computer controls the second electronic switches to be simultaneously closed and the first electronic switches to be simultaneously opened in a short circuit mode of the phases of the motor, the computer having an operating mode designed to implement said configurations in accordance with the control phases of the mobile vehicle.

[0013] The mobile vehicle may be a remotely controlled wheeled vehicle and said configuration may be initiated by controls received by the computer over a communications link from an external controller.

[0014] The vehicle is a wheeled vehicle operated by manual control, and the computer may be programmed to initiate a freewheel configuration after release of the manual control.

[0015] The vehicle is a wheeled vehicle operated by manual control, and the computer can be programmed to initiate a motor braking arrangement after release of the manual control.

[0016] The vehicle is a wheeled vehicle operated by manual control and the computer can be programmed to initiate a motor braking configuration F when a maximum travel speed MAX of said vehicle is exceeded.

[0017] The computer can be programmed to initiate the motor braking configuration F after release of manual control to immobilize the vehicle, and then initiate the freewheel configuration when the vehicle has come to a stop to allow the vehicle to be moved freely by hand.

[0018] The computer may have a mode to maintain the motor braking configuration when the motor is stopped in order to park the vehicle.

[0019] The present disclosure also relates to a mobile electric vehicle comprising at least one wheel associated with a motor controlled by a control system as described above.

[0020] Other features, details and advantages of the invention will become apparent from reading the following detailed description of non-limiting embodiments and from examining the accompanying drawings. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a simplified schematic diagram of a first embodiment of a motorized control system. [Diagram 2] FIG. 4 is a simplified schematic diagram of a second embodiment of a motorized control system. [Diagram 3] FIG. 2 illustrates diagrammatically the operating modes of the described motorized control system; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The following figures and description contain elements which may facilitate an understanding of the invention as well as contribute, where appropriate, to the definition of the invention.

[0023] The present disclosure relates to an embodiment of a motorized control system for at least one wheel 12 driven by a motor 1, as shown in Figures 1 and 2. The wheels 12 may be wheels of a wheeled vehicle, such as an industrial truck, which may be equipped with one motorized control system per wheel, the system being optionally individually synchronizable or controllable to allow directional control of the truck by adapting the speed of each wheel, or the system may control two wheels depending on the configuration of the wheeled vehicle.

[0024] The motorized control system according to a first exemplary embodiment shown in FIG. 1 comprises an electronic control system for controlling said motor, comprising a main power device 4 supplying power to said phases of a motor and supplying power to a power half-bridge 2a, 2b, 2c provided with an upper arm having a first electronic switch 21a, 21b, 21c mounted thereon and a lower arm having a second electronic switch 22a, 22b, 22c mounted thereon, said electronic control system further comprising a programmable computer 3 for controlling said first and second electronic switches by means of a control output 3a for said electronic switches.

[0025] More specifically, the system includes at least a. 3-phase brushless DC motor (BLDC) 1, b. an electronic system having three power half-bridges 2a, 2b, 2c, i.e. six MOSFET or IGBT electronic power switches, three first switches 21a, 21b, 21c on the upper branch of the half-bridges and three second switches 22a, 22b, 22c on the lower branch of the half-bridges; c. a programmable computer 3 for controlling the six switches independently of each other; d. A primary power source such as a battery4 internal or external to the system It consists of:

[0026] The motorised control system may be connected to an external controller 5 or a computerised parameterisation tool such as a laptop computer or tablet 5a via a communications link 6, which may be wired or wireless.

[0027] The system is not limited to the three-phase configuration shown, or to a configuration having a single switch in a branch of a half-bridge, but may have more phases and parallel switches on the branches depending on the power of the motor being controlled.

[0028] In this configuration, the computer sequentially controls the electronic switches of the three half-bridges to generate a rotating electric field that rotates the motor. In addition to sequential control, according to the present disclosure, the computer is configured to control the switches in two different ways to produce different behaviors in the motor. a. Six switches are open to allow the motor to rotate freely without producing current in the phases; this mode is called "freewheeling." b. The three second electronic switches 22a, 22b, 22c on the lower branch are closed and the three first switches on the upper branch are opened, which creates a short circuit current between the three phases of the motor during the rotation of the motor, resulting in a resistive magnetic force opposing this rotation, this mode is called "motor braking".

[0029] In this embodiment, the computer and half bridges need to remain powered when the motor is braked, and the computer control switching requires that a switch on the upper branch be open while a switch on the lower branch is simultaneously closed.

[0030] As mentioned above, if the moving vehicle is motorized, the control system allows obtaining movement without resistance from the motor in a "freewheel" mode without activating the motorization, or conversely helps to slow down or immobilize the vehicle in a "motor braking" mode.

[0031] It is therefore useful to be able to parameterize the operating modes of the power switch, and in particular to be able to combine different modes depending on the phase of use, which offers a wide range of options for the settings that determine the behavior of the motorized system.

[0032] To allow the user of the system to access different combinations of behaviors, a computerized parameterization tool can be part of an external controller 5 connected to the computer 3 via a USB, CAN, Ethernet or Wi-Fi communication link 6 or another data exchange means such as infrared. The computerized tool hosts a parameterization software that allows the user to select the desired switching mode depending on the motorization use mode.

[0033] If the motorization of the wheeled vehicle is actuated by manual control, such as the control device 11, these options, which are shown diagrammatically in FIG. 3, can be, for example: a. Generation of manual start control M110 followed by sequential operation Seq140 of the switches to drive the motor and the tractive force T of the vehicle; b. Switching to freewheel RL180 as a result of opening of electronic switches on the upper and lower arms followed by release of manual control R170 in order to travel without electric drive; c. Switching to motor braking F160 as a result of the first switch opening and the second switch CCpi closing following the stop control Stop to help slow the vehicle by electric braking. This can also be done following the release of the manual control R instead of switching to the freewheel 180, d. Switching on motor braking F150 when the speed V of the vehicle exceeds a maximum defined speed MAX120, thereby enabling the maximum travel speed to be adjusted; e. Release of manual control followed by switching on motor braking F to immobilize the vehicle and then switching to "freewheel" RL180 at zero speed to allow the vehicle to move freely manually; f. Maintaining "motor braking" to park the vehicle It is also possible to do the following.

[0034] Control using the above described operating modes is particularly suitable for industrial trucks with maneuvering assistance. The braking mode provided by shorting phases saves electricity since braking is generated by shorting motor phases and not by activating an electric braking device, and also increases safety by limiting speed, optionally in combination with a freewheel mode, if the vehicle is moving too fast.

[0035] Thus, Fig. 3 shows diagrammatically possible operating modes based on a power source A100 of the system with a normal sequential control operation Seq140 of the electronic switches following a start command M110 for the vehicle, switching the electronic switch on the lower arm of the half-bridge to short circuit 150 and opening the switch on the upper arm in order to switch to motor braking if the speed of the vehicle exceeds a maximum speed Max during a test 120, switching the electronic switch on the lower arm of the half-bridge to short circuit 160 and opening the switch on the upper arm in order to switch to motor braking following the release of a manual control or stop command during a test 130, and opening the electronic switches on the lower and upper branches of the half-bridge 180 following the detection of an command to switch to freewheel 170, release the control or detect zero speed. This allows braking in the presence of the power source A while leaving the switches of the half-bridge open.

[0036]

number

[0037] Control of these different modes by the computer, as well as control of the power switch, is only possible if power is present. In battery-powered systems, there is the possibility of loss of power during operation if the battery is depleted or unable to provide current.

[0038] In this case, loss of the braking function may be problematic in the event of a loss of power, especially if this function is activated to keep the vehicle stationary and parked: uncontrolled loss of the braking function may represent a safety risk.

[0039] The control system according to the embodiment in Fig. 2 corresponds to an embodiment with a safety circuit short-circuiting the lower branch to protect the braking function for a given time after the loss of electrical energy. This system comprises an additional, optionally parameterizable or programmable, switching circuit 7, provided with at least one channel 7a for detecting an interruption of the main power supply and with a switching designed to generate a control signal for closing a third switch 9a, 9b, 9c via a control channel 7d, said third switch being wired in parallel with the second switch 22a, 22b, 22c on the lower branch of the half-bridge to provide an emergency stop function by short-circuiting the phases of the motor. This additional switching circuit is powered by an energy storage 8 forming a secondary power supply that allows the safety circuit and the control device for the switches of the additional switching circuit to operate for a sufficient time to stop the motor and the motorized wheels even in the event of a loss of the main power supply of the control system.

[0040] The energy store can be generated based on an electrochemical capacitor or a supercapacitor powered by the main power supply 4 via a diode 10 or by a first DC / DC converter, and a voltage regulator can be inserted between the energy store 8 and the additional switching circuit 7 of the safety circuit, with or without a second DC / DC converter, to bring the voltage of the charged energy store to a voltage acceptable for the additional switching circuit 7, for example 4 V to 6 V, while the main power supply, when active, supplies a voltage of, for example, 12 V to 48 V.

[0041] The energy storage can also be generated by a buffer battery if higher autonomy of the safety circuit is required.

[0042] The third switches 9a, 9b, 9c for shorting the phases can be made by MOSFET transistors, which have the advantage that they do not need to be dimensioned to control the power and require a very small current to remain switched on.

[0043] If the system suffers a loss of electrical energy from the mains, the safety circuit may trigger the activation of the third switch to the on mode by means of an additional switching circuit, or this additional switching circuit may trigger said activation automatically following the detection of a drop in the mains voltage. The additional switching circuit 7 may also be self-maintaining the voltage for activating the switch to the on mode, as long as the energy store provides a residual voltage of a few volts. This energy store is appropriately dimensioned, for example in terms of storage capacity, to guarantee a current to maintain the on mode of the third switch for several minutes. This minimum maintenance time is guaranteed by the dimensioning of the energy store and the typology of the additional switching circuit.

[0044] The circuit is a MOSFET transistor circuit for low power consumption and is configured to close the third switch when the voltage at link 7a drops below a threshold set by the voltage across the terminals of capacitor 8.

[0045] This device for maintaining braking guarantees motor braking function for a minimum defined period of time even in the event of loss or failure of the main power supply and can therefore be considered as a safety feature eliminating the conventional need for an electromechanical brake in the absence of current.

[0046] The system may optionally be complemented by a conventional mechanical parking brake when the wheeled vehicle must be parked on an incline for extended periods of time.

[0047] In the example shown, the system comprises a manual control 11 acting on the programmable computer 3. The manual control may be provided in addition to a remote control via a communication link 6 from the external controller 5, or may replace the remote control under normal operation, in which case the external controller 5 is used only for programming the system.

[0048] Loss of power is shown diagrammatically in FIG. 3 at step 190 and a third switch to short out the phases of the motor is closed to generate emergency braking at step 200 .

[0049] The present invention is not limited to the examples described above, which are provided purely by way of example, but encompasses all the variants that may be envisaged by a person skilled in the art in the context of the desired protection, in particular the motor may comprise more than three phases and more than four half-bridges. [Explanation of symbols]

[0050] 1 Motor, 3-phase brushless DC motor (BLDC) 2a Power Half Bridge 2b Power Half Bridge 2c Power Half Bridge 3 Programmable Computer, Computer 3a Control Output 4 Batteries, mains power, and mains powered devices 5 External Controller 5a Laptop computer or tablet 6 Communication links, Wi-Fi communication links 7 Additional switching circuits 7a Channel, Link 7b Control Channel 7c Control Output 7d Control Channel 8 Energy storage, capacitors, secondary power devices 9a Third Switch 9b Third Switch 9c Third Switch 10. Diodes 11 Control device, manual control device, manual control 12 wheels 21a First electronic switch 21b First electronic switch 21c First Electronic Switch 22a Second Electronic Switch 22b Second Electronic Switch 22c Second Electronic Switch

Claims

1. A motorisation control system for a mobile electric vehicle comprising at least a three-phase brushless DC motor (1) and an electronic control system for controlling said motor, said electronic control system further comprising a programmable computer (3) for controlling, by means of a control output (3a) for said electronic switches (21a, 21b, 21c), at least a first drive mode of said motor based on sequential switching control of said switches for generating a rotating electric field which rotates said motor, and a second freewheel mode in which said electronic switches of said power half-bridges are open, 1. A motorized control system for a mobile electric vehicle, characterized in that the motorized control system comprises a safety circuit designed to generate an emergency braking mode FS (200) and provided with a third electronic switch (9a, 9b, 9c) for shorting the lower arm of the half-bridge in parallel with the second electronic switch (22a, 22b, 22c), the third electronic switch being controlled by an additional switching circuit (7) provided with a detection channel (7a) for detecting an interruption (190) of the main power supply device (4) and / or a control channel (7b) from the programmable computer and designed to close the third switch to generate emergency braking, the additional switching circuit being powered by a secondary power supply device (8).

2. 2. The motorised control system for a mobile electric vehicle of claim 1, wherein the additional switching circuit comprises an inhibit output (7c) to the control outputs for the first and second switches (21a, 21b, 21c, 22a, 22b, 22c) to force the first and second switches to an open position when the third switch is closed.

3. 3. A motorized control system for a mobile electric vehicle as claimed in claim 1 or 2, wherein the secondary power source device (8) is generated by a capacitor or supercapacitor energy storage.

4. 4. The motorised control system for a mobile electric vehicle according to any one of claims 1 to 3, wherein the computer includes a configuration programming mode including a traction configuration (140) in which the computer (3) controls the first and second electronic switches (21 a, 21 b, 21 c, 22 a, 22 b, 22 c) based on a sequential control, a freewheel configuration (150) in which the computer controls the first and second electronic switches (21 a, 21 b, 21 c, 22 a, 22 b, 22 c) to be open, and a motor braking configuration (160) in which the computer controls the second electronic switches (22 a, 22 b, 22 c) to be simultaneously closed and the first electronic switches (21 a, 21 b, 21 c) to be simultaneously opened in a short circuit mode of the phase of the motor, and wherein the computer has an operating mode designed to implement the configurations according to a control phase of the mobile electric vehicle.

5. 5. The motorised control system for a mobile electric vehicle as claimed in claim 4, wherein the mobile vehicle is a remotely controlled wheeled vehicle and the configuration is initiated by controls received by the computer from an external controller (5) via a communications link (6).

6. 5. The motorized control system for a mobile electric vehicle of claim 4, wherein the vehicle is a wheeled vehicle operated by manual control (11), and the computer (3) is programmed to initiate the freewheel configuration (150) after release of the manual control.

7. 5. The motorized control system for a mobile electric vehicle of claim 4, wherein the vehicle is a wheeled vehicle operated by manual control (11), and the computer (3) is programmed to initiate the motor braking arrangement (160) after release of the manual control.

8. 5. The motorized control system for a mobile electric vehicle according to claim 4, wherein the vehicle is a wheeled vehicle operated by manual control (11) and the computer (3) is programmed to initiate a motor braking arrangement F (150) when a maximum travel speed MAX (120) of the vehicle is exceeded.

9. 9. The motorized control system for a mobile electric vehicle of claim 8, wherein the computer (3) is programmed to initiate the motor braking configuration (160) after release (130) of the manual control (11) to immobilize the vehicle, and then initiate the freewheel configuration (150) when the vehicle comes to a stop to allow the vehicle to move freely manually.

10. 5. The motorized control system for a mobile electric vehicle of claim 4, further comprising maintaining said motor braking configuration (160) when said motor is stopped to park said vehicle.

11. A mobile electric vehicle comprising at least one wheel (12) associated with a motor (1) controlled by a motorized control system for a mobile electric vehicle according to any one of claims 1 to 10.

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