Motor control system with electric safety braking

Abstract

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

Description

ENGINE CONTROL SYSTEM WITH ELECTRIC SAFETY BRAKING Technical field

[0001] The invention relates to the field of electric motorized systems or vehicles such as autonomous motorized carts or those guided by an external control system, such as handling carts for automated warehouses or the like. Prior art

[0002] It is known to produce autonomous electric motorized vehicles such as mobile robots that move around premises such as automated warehouses to load and unload parcels or mobile robots performing tasks such as floor cleaning tasks for example.

[0003] Such a vehicle comprises one or more electric motors for driving the vehicle's wheels, an on-board computer for managing the operation of the motors, a battery for supplying the motor or a power rail in the case of trolleys on rails and possibly a communication card with a remote control centre giving the vehicle movement orders to the on-board computer. Technical problem

[0004] The operational safety of these vehicles requires that they always be able to brake even in the event of a loss of power to the engine(s), and it is known to equip these vehicles with a mechanical emergency braking device or a bulky electric brake containing wearing parts.

[0005] Document EP 3 618 259 A1 relates to a device in which switches of a lower half-bridge are short-circuited by means of a voltage loss detection circuit and an emergency power supply. This device is complex and does not allow braking to be maintained or braking to be controlled in freewheel phases. Statement of the invention

[0006] In view of the prior art, the present application proposes a system for controlling the motorization of an electric motor of an electric mobile machine provided with an electric braking device implemented in the event of loss of power supply to the motor controller, this device being furthermore able to be used as a controlled braking device in freewheel phases.

[0007] To do this, the present disclosure proposes a motorization control system for an electric mobile machine comprising a brushless DC motor with at least three phases, an electronic system for controlling said motor comprising a main electrical power supply device for supplying power half-bridges for supplying said phases of the motor and provided with upper arms equipped with first electronic switches and lower arms equipped with second electronic switches,said control system further comprising a programmable computer for controlling said first and second electronic switches by means of control outputs of said electronic switches to produce at least a first mode of driving the motor according to a sequential control of switching of the switches to create the rotating electric field ensuring the rotation of the motor and a second freewheel mode for which the electronic switches of said power half-bridges are open, which comprises a safety circuit, adapted to produce an emergency braking mode FS, provided with third electronic switches for short-circuiting the lower arms of the half-bridges in parallel with said second electronic switches,said third electronic switches being controlled by an additional switching circuit provided with a path for detecting a cut-off of the main electrical power supply device and / or a control path from said programmable computer and adapted to close said third switches to carry out said emergency braking, said additional switching circuit being powered by a secondary electrical power supply device.,

[0008] Advantageously, said additional switching circuit comprises an output for inhibiting the control outputs of said first and second switches so as to force said first switches and second switches into the open position when said third switches are closed.

[0009] Advantageously, the secondary power supply device is produced by means of an energy reserve with capacitors or supercapacitors.

[0010] According to a complementary or independent embodiment, the system is configured to offer three operating modes, a first mode comprising a power supply to the motor to tow the vehicle, a second mode for which the motor is in freewheel mode and a third mode for which the motor is electrically braked.

[0011] To do this, the motorization control system for an electric mobile machine is such that the computer comprises a configuration programming mode comprising a traction configuration T according to which the computer controls the first and second electronic switches according to said sequential control, a freewheel configuration RL according to which the computer controls an opening of the first and second electronic switches and an engine brake configuration F according to which the computer controls a simultaneous closing of the second electronic switches and a simultaneous opening of the first electronic switches in a short-circuit mode of the phases of the motor, said computer comprising an operating mode adapted to implement said configurations according to control phases of said mobile machine.

[0012] The mobile machine being a remotely controlled rolling machine, said configurations can be initiated by commands received by the computer through a communication link from an external controller.

[0013] Since the machine is a rolling machine operated by a manual control, the computer can be programmed to initiate the freewheel configuration when the manual control is released.

[0014] Since the machine is a rolling machine operated by a manual control, the computer can be programmed to initiate the engine brake configuration when the manual control is released.

[0015] Since the machine is a rolling machine operated by a manual control, the computer can be programmed to initiate the engine brake configuration F beyond a maximum rolling speed MAX of said machine.

[0016] The computer can be programmed to initiate the engine brake configuration F when the manual control is released to immobilize the machine and then initiate the freewheel configuration with the machine stopped to be able to move the machine freely by hand;

[0017] The calculator can include a mode for maintaining the engine brake configuration, with the engine stopped to park the machine.

[0018] The present disclosure further relates to an electrically powered mobile machine comprising at least one wheel associated with a motor controlled by a control system as described previously. Brief description of the drawings

[0019] Other characteristics, details and advantages of the invention will appear on reading the detailed description below of non-limiting exemplary embodiments, and on analyzing the appended drawings, in which:

[0020] [Fig. 1] shows a simplified diagram of a first embodiment of a motor control system;

[0021] [Fig. 2] shows a simplified diagram of a second embodiment of a motor control system;

[0022] [Fig. 3] schematically represents operating modes of a described motor control system. Description of the embodiments

[0023] The following drawings and description contain elements which may not only serve to better understand the present invention, but also contribute to its definition, where appropriate.

[0024] The present disclosure relates, according to figures 1 and 2, to embodiments of motorization control systems for at least one wheel 12 driven by a motor 1. The wheel 12 may be a wheel of a rolling machine such as a handling trolley which may comprise a motorization control system per wheel, the systems possibly being able to be synchronized or controlled independently to allow directional control of the trolley by adapting the speeds of each wheel or the system may control two wheels according to the configuration of the rolling machine.

[0025] The motorization control system according to a first exemplary embodiment of Figure 1 comprises an electronic system for controlling said motor comprising a main electrical power supply device 4 for supplying power half-bridges 2a, 2b, 2c for supplying said phases of the motor and provided with upper arms equipped with first electronic switches 21a, 21b, 21c and lower arms equipped with second electronic switches 22a, 22b, 22c, said electronic control system further comprising a programmable computer 3 for controlling said first and second electronic switches by means of outputs 3a for controlling said electronic switches

[0026] More precisely, the system is composed of at least: a. - A three-phase brushless DC motor (BLDC); b. - An electronic system with three power half-bridges 2a, 2b, 2c, i.e. six electronic power switches with MOSFET or IGBT, three first switches 21a, 21b, 21c in upper branches of the half-bridges and three second switches 22a, 22b, 22c in lower branches of the half-bridges; c. - A programmable computer 3 for controlling the six switches independently of each other; d. - A main power source such as a battery 4 internal or external to the system.

[0027] The motor control system can be connected to a computer configuration tool such as an external controller 5 or a laptop or tablet 5a via a communication link 6 which can be wired or radio.

[0028] The system is not limited to the three-phase configuration shown and a configuration with single switches in the half-bridge branches but can have a higher number of phases and switches in parallel in the branches depending on the electrical power of the motor to be controlled.

[0029] In this configuration, the computer controls the electronic switches of the three half-bridges sequentially to create the rotating electric field ensuring the rotation of the motor. In addition to sequential control, according to the present disclosure the computer is configured to control the switches in two distinct ways generating different behavior at the motor: a. - Opening of the six switches to let the motor rotate freely without generating electric current in the phases, this mode being called "freewheel"; b. - Closing of the second three electronic switches 22a, 22b, 22c of the lower branches and opening of the first three electronic switches of the upper branches, which creates a short-circuit current between the three phases of the motor during its rotation and generates a magnetic resistance force opposing this rotation, this mode being called "motor brake".

[0030] In this embodiment it is necessary that the computer and the half-bridges remain powered when the engine is to be braked. It is also necessary that the computer control switching opens the switches of the upper branches when the switches of the lower branches are closed simultaneously.

[0031] As seen above, in the case of the motorization of a mobile machine, the control system allows for rolling without actuation of the motorization and without resistance of the motor in “freewheel” mode, or on the contrary to help decelerate or immobilize the machine in “engine brake” mode.

[0032] It is therefore useful to be able to configure the mode of action of the power switches, and in particular to be able to combine the different modes according to the phases of use. The combination of modes gives rise to a wide choice of possible settings for the behavior of the motorization system.

[0033] In order to make the different combinations of behaviors accessible to the user of the system, the computer configuration tool can be part of an external controller 5 connected to the computer 3 via a communication link 6 of the USB, CAN, Ethernet, Wi-Fi type or other means of data exchange, infrared for example. The computer tool hosts configuration software allowing the user to choose the desired switching modes according to the modes of use of the motorization.

[0034] In the case of the motorization of a rolling machine actuated by a manual control such as the control 11, these choices shown diagrammatically in figure 3 can for example be: a. - Sequential operation Seq 140 of the switches to drive the engine and the traction T of the vehicle on engagement of a manual drive control M 110; b. - Switching to freewheel RL 180 by opening the electronic switches of the upper arms and lower arms on release R 170 of the manual control, to drive without electric drive, or, c. - Switching to engine braking F 160 by opening the first switches and closing the second switches CCpi on a stop control Stop, to assist in decelerating the machine by electric braking. This can also be done on release R of the manual control instead of switching to freewheel 180; d.- Switching to engine braking F 150 if the machine's speed V exceeds a defined maximum speed MAX 120, this allows the maximum driving speed to be regulated; e. - Switch to engine brake F when releasing the manual control to immobilize the machine then switch to “freewheel” RL 180 at zero speed to be able to move the machine freely by hand; f. - Maintain “engine brake” to park the machine.

[0035] Control using the operating modes described above is particularly suitable for handling trucks with handling assistance. The braking mode by short-circuiting the phases allows a saving in electrical consumption since the braking is carried out by short-circuiting the motor phases and not by actuating an electric braking device, it allows increased safety if the machine is going too fast by limiting the speed and allows, possibly in combination with the freewheel mode, to regulate the speed of the machine.

[0036] Figure 3 thus shows the possible operating modes from a power supply A 100 of the system with the normal operation of sequential control Seq 140 of the electronic switches on a running order M 110 of the vehicle, short-circuiting 150 of the electronic switches of the lower arms and opening of the switches of the upper arms of the half-bridges to switch to engine braking if the speed of the vehicle has exceeded a maximum speed Max in test 120, short-circuiting 160 of the electronic switches of the lower arms and opening of the switches of the upper arms of the half-bridges to switch to engine braking on release of the manual control or stop order in test 130, opening of the electronic switches of the lower and upper branches of the half-bridges 180 on detection of a freewheeling order 170, release of the control or detection of zero speed.This allows when power supply A is present to brake while keeping the half-bridge switches open.

[0037] In the event of a power failure or loss of power supply  190, braking by closing the third switches 9a, 9b, 9c and short-circuiting the phases CCbi performs a safety motor brake function FS at step 200.

[0038] The control of these different modes by the computer and the piloting of the power switches is only possible in the presence of energy. For In battery-powered systems, loss of power during operation is possible when the battery is empty or unable to deliver current.

[0039] In this case, the loss of braking function can be problematic at the time of energy loss, especially when this function is activated to keep a vehicle stationary in parking. Uncontrolled loss of braking function can represent a safety risk.

[0040] The control system according to the embodiment of Figure 2 corresponds to an embodiment which comprises a safety circuit ensuring short-circuiting of the lower branches for the purpose of safeguarding the braking function for a certain time after a loss of electrical energy. This system comprises an additional switching circuit 7 which may be parameterized or programmable, which is provided with at least one channel 7a for detecting a cut-off of the main power supply and which comprises a switching circuit adapted to generate a control signal for closing third switches 9a, 9b, 9c, via a control channel 7d, said third switches being wired in parallel with the second switches 22a, 22b, 22c of the lower branches of the half-bridges to ensure an emergency stop function by short-circuiting the phases of the motor.This additional switching circuit is powered by an energy reserve 8 forming a secondary power supply allowing the safety circuit and the controls of the switches by the additional switching circuit to operate for a time sufficient to stop the motor and the motorized wheel even in the event of loss of the main power supply to the control system.

[0041] The energy reserve can be made from an electrochemical capacitor or a supercapacitor powered by the main power source 4 through a diode 10 or by a first DC / DC converter and it is possible to introduce between the energy reserve 8 and the additional switching circuit 7 of the safety circuit a voltage regulator with or without a second DC / DC converter to bring the voltage of the charged energy reserve to an acceptable voltage for the additional switching circuit 7, for example 4 V to 6 V while the main power source delivers when active a voltage of 12 V to 48 V for example.

[0042] The energy reserve can also be provided by a buffer battery if greater autonomy of the safety circuit is desired.

[0043] The third phase short-circuit switches 9a, 9b, 9c can be made by MOSFET transistors which do not need to be sized to control power and which have the advantage of consuming very little current to remain switched closed.

[0044] In the event of a loss of electrical energy suffered by the system at the main power supply, the safety circuit can trigger the activation of the third switches in on-mode by means of the additional switching circuit or this additional switching circuit can, upon detection of a drop in the main power supply voltage, trigger said activation automatically. The additional switching circuit 7 can also self-maintain the activation voltage of the switches in on-mode as long as the energy reserve provides a residual voltage of a few Volts. This energy reserve is dimensioned sufficiently, for example in storage capacity to guarantee the holding current in on-mode of the third switches for a time of several minutes. This minimum holding time is guaranteed by the dimensioning of the energy reserve and the typology of the additional switching circuit.

[0045] This circuit is a mosfet transistor type circuit for low consumption and is configured to control the closing of the third switches when the voltage on link 7a becomes lower than a threshold set by the voltage across capacitor 8.

[0046] This brake holding device allows the motor brake function to be guaranteed for a defined minimum duration even in the event of loss or failure of the main power supply, and can therefore be considered a safety function, avoiding the classic use of an electromechanical brake in the event of a power failure.

[0047] This system can optionally be supplemented by a traditional mechanical parking brake if the vehicle has to be parked for a long time on sloping ground.

[0048] In the example shown, the system comprises a manual control 11 acting on the programmable computer 3. The manual control can be in addition to a remote control via a communication link 6 from the external controller 5 or replace the remote control in normal operation, the external controller 5 then only serving for programming the system.

[0049] The loss of power supply is shown diagrammatically in Figure 3 at step 190 and the closing of the third short-circuit switches of the motor phases to carry out emergency braking is carried out at step 200.

[0050] The invention is not limited to the examples described above, only by way of example, but it encompasses all the variants that a person skilled in the art may envisage within the framework of the protection sought and in particular, the motor may comprise more than three phases and the converter more than three half-bridges.

Claims

Demands

1. Motor control system for electric mobile machinery comprising a motor (1) with at least three phases brushless direct current, an electronic control system for said motor comprising a main power supply device (4) for supplying power half-bridges (2a, 2b, 2c) for supplying said phases of the motor and having upper arms equipped with first electronic switches (21a, 21b, 21c) and lower arms equipped with second electronic switches (22a, 22b, 22c),said electronic control system further comprising a programmable computer (3) for controlling said first and second electronic switches by means of control outputs (3a) of said electronic switches to achieve at least a first mode of motor drive according to a sequential switching control of the switches to create the rotating electric field ensuring the rotation of the motor and a second freewheeling mode for which the electronic switches of said power half-bridges are open, characterized in that it comprises a safety circuit, adapted to produce an emergency braking mode FS (200), provided with third electronic switches (9a, 9b, 9c) for short-circuiting the lower arms of the half-bridges in parallel with said second electronic switches (22a, 22b, 22c),said third electronic switches being controlled by an additional switching circuit (7) provided with a channel (7a) for detecting a break (190) in the main power supply device (4) and / or a control channel (7b) from said programmable computer and adapted to close said third switches to perform said emergency braking, said additional switching circuit being powered by a secondary power supply device (8).

2. A motor control system for an electric mobile machine according to claim 1, wherein said additional switching circuit comprises an output (7c) for inhibiting the control outputs of said first and second switches (21a, 21b, 21c, 22a, 22b, 22c) so as to force said first and second switches into the open position when said third switches are closed.

3. Motor control system for electric mobile machinery according to claim 1 or 2, wherein the secondary power supply device (8) is made by means of a capacitor or supercapacitor energy reserve.

4. A motor control system for an electric mobile machine according to any one of the preceding claims, wherein the control unit comprises a configuration programming mode comprising a traction configuration (140) in which the control unit (3) controls the first and second electronic switches (21a, 21b, 21c, 22a, 22b, 22c) according to said sequential control, a freewheeling configuration (150) in which the control unit commands an opening of the first and second electronic switches (21a, 21b, 21c, 22a, 22b, 22c) and an engine braking configuration (160) in which the control unit commands a simultaneous closing of the second electronic switches (22a, 22b, 22c) and a simultaneous opening of the first electronic switches (21a, 21b, 21c) in a short-circuit mode of the motor phases,said computer comprising an operating mode adapted to implement said configurations according to piloting phases of said mobile device.

5. Motorization control system for electric mobile machinery according to claim 4, wherein, the mobile machinery being a remotely piloted rolling machine, said configurations are initiated by commands received by the computer through a link (6) from an external controller (5).

6. Motorization control system for electric mobile machinery according to claim 4, wherein, the machinery being a rolling machine operated by a manual control (11), the computer (3) is programmed to initiate the freewheeling configuration (150) upon release of the manual control.

7. Motorization control system for electric mobile machinery according to claim 4, wherein, the machinery being a rolling machine operated by a manual control (11), the computer (3) is programmed to initiate the motor brake configuration (160) upon release of the manual control.

8. Motorization control system for electric mobile machinery according to claim 4, wherein, the machinery being a rolling machine operated by a manual control (11), the computer (3) is programmed to initiate the motor brake configuration F (150) beyond a maximum rolling speed MAX (120) of said machinery.

9. Motorization control system for electric mobile machine according to claim 8, wherein the computer (3) is programmed to initiate the motor brake configuration F (160) upon release (130) of the manual control (11) to immobilize the machine and then initiate the freewheel configuration (150) when the machine is stopped so that the machine can be moved freely by hand;

10. Motorization control system for electric mobile machinery according to claim 4, comprising maintaining the motor brake configuration (160), motor stopped to park the machinery.

11. Electrically powered mobile device comprising at least one wheel (12) associated with a motor (1) controlled by a control system according to any one of the preceding claims.

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