Motor control system with electrically safe braking

Abstract

The invention relates to a motor control system for an electric vehicle, comprising a brushless DC motor (1) having at least three phases. The electronic system for controlling the motor comprises a main power supply device (4) for powering a power half-bridge (2a, 2b, 2c) for powering the phases of the motor and provided with an upper arm equipped with a first electronic switch (21a, 21b, 21c) and a lower arm equipped with a second electronic switch (22a, 22b, 22c). The control system further comprises a programmable computer (3) for controlling the first and second electronic switches by means of an output (3a) for controlling the electronic switches to implement at least a first drive mode and a second freewheeling mode of the motor, the first driving mode is switched and controlled according to the sequence of the switches to create a rotating electric field ensuring rotation of the motor, and the second freewheeling mode is that the electronic switches of the power half-bridge are turned off. The system comprises a safety circuit adapted to generate an emergency braking mode and provided with a third electronic switch (9a, 9b, 9c) in parallel with the second electronic switch (22a, 22b, 22c) for short-circuiting the lower arm of the half-bridge. The third electronic switch is controlled by an additional switching circuit (7) provided with a channel (7a) for detecting a disconnection of the main power supply (4) and / or a control channel (7b) from the programmable computer and adapted to close the third switch to perform the 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, either autonomously or guided by an external control system, such as industrial trucks for automated warehouses or the like. Background Art

[0002] It is known to produce autonomous electric vehicles, such as mobile robots that move around a premises such as an automated warehouse to load and unload packages, or that perform tasks such as floor cleaning.

[0003] Such a vehicle has one or more electric motors for driving the vehicle's wheels, an onboard computer for managing the operation of the motors, power batteries for the motors or, in the case of a rail truck, powered rails, and optionally a board for communicating with a remote control center which provides the onboard computer with instructions for the movement of the vehicle.

[0004] Technical issues

[0005] The safe operation of these vehicles requires the ability to permanently brake the vehicle, even in the event of a loss of power to one or more motors, and it is known to equip these vehicles with mechanical emergency brakes or electromagnetic brakes which are cumbersome and include wearing parts.

[0006] Document EP 3618259 A1 relates to a device in which the switches of the lower half-bridge are short-circuited using a voltage loss detection circuit and an emergency power supply. This device is complex and does not allow the braking to be maintained or controlled during the freewheeling phase. Summary of the invention

[0007] Taking into account the prior art, the present application proposes a motorised control system for an electric motor of a mobile electric vehicle provided with an electrical braking device for use in the event of a loss of power to the motor's controller, which device can also be used as a controlled braking device during the freewheeling phase.

[0008] For this purpose, the present disclosure proposes a motorized control system for moving an electric vehicle, the motorized control system comprising at least a three-phase brushless DC motor, an electronic control system for controlling the motor, the electronic control system comprising a main power supply device, the main power supply device supplies power to a power half-bridge, the power half-bridge supplies power to the phases of the motor and is provided with an upper arm equipped with a first electronic switch and a lower arm equipped with a second electronic switch, the control system further comprising a programmable computer, the programmable computer is used to control the first and second electronic switches by means of control outputs for the electronic switches to generate at least a first drive mode and a second freewheeling mode of the motor, the first drive mode being Based on the sequential switching control of the switches to create a rotating electric field to rotate the motor, in the second freewheeling mode, the electronic switch of the power half-bridge is disconnected, and the motorized control system includes a safety circuit, which is designed to generate an emergency braking mode FS and is provided with a third electronic switch connected in parallel with the second electronic switch for short-circuiting the lower arm of the half-bridge, and the third electronic switch is controlled by an additional switching circuit, and the additional switching circuit is provided with a detection channel for detecting an interruption of the main power supply device, and / or is provided with a control channel from the programmable computer and designed to close the third switch to generate the emergency braking, and the additional switching circuit is powered by a secondary power supply device.

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

[0010] Advantageously, the secondary power supply is produced by a capacitor or supercapacitor energy store.

[0011] According to a supplementary or separate embodiment, the system is configured to provide three operating modes: a first mode, which includes supplying power to the motor to provide traction for the vehicle; a second mode, in which the motor is freewheeling; and a third mode, in which the motor is electrically braked.

[0012] For this purpose, a motorized control system for a mobile electric vehicle enables a computer to include a configuration programming mode, wherein the configuration programming mode includes a traction configuration T, a freewheeling configuration RL, and a motor braking configuration F. In the traction configuration T, the computer controls the first and second electronic switches based on the sequential control. In the freewheeling configuration RL, the computer controls the first and second electronic switches to be disconnected. In the motor braking configuration F, the computer controls the second electronic switch to be closed simultaneously and controls the first electronic switch to be opened simultaneously in a short-circuit mode of the motor's phases. The computer has an operating mode designed to implement the configuration according to the control stage of the mobile vehicle.

[0013] The mobile vehicle is a remotely controlled wheeled vehicle and the configuration may be initiated by control received by the computer from an external controller via a communication link.

[0014] The vehicle is a wheeled vehicle actuated by manual control and the computer may be programmed to initiate a freewheeling configuration after the manual control is released.

[0015] The vehicle is a wheeled vehicle actuated by manual controls and the computer may be programmed to activate a motor braking configuration after the manual controls are released.

[0016] The vehicle is a wheeled vehicle actuated by manual control and the computer may be programmed to activate the motor braking arrangement F if the vehicle exceeds a maximum moving speed MAX.

[0017] The computer may be programmed to initiate the motor braking configuration F after the manual controls are released to immobilize the vehicle, and then initiate the freewheeling configuration when the vehicle has stopped to enable the vehicle to be moved freely by hand.

[0018] The computer may have a mode for maintaining the motor braking configuration when the motor has 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Other features, details and advantages of the present invention will become apparent upon reading the following detailed description of non-limiting exemplary embodiments and analyzing the accompanying drawings, in which:

[0021] [ Figure 1 ] is a simplified diagram of a first embodiment of a motorized control system;

[0022] [ Figure 2 ] is a simplified diagram of a second embodiment of a motorized control system;

[0023] [ Figure 3 ] schematically illustrates the operating mode of the described motorized control system. DETAILED DESCRIPTION

[0024] The following drawings and description contain elements that not only make the invention easier to understand but also contribute to its definition where appropriate.

[0025] The present disclosure relates to embodiments of a motorized control system for at least one wheel 12 driven by a motor 1, such as Figure 1 and 2The wheels 12 may be wheels of a wheeled vehicle such as an industrial truck, which may include a motorized control system for each wheel, the system optionally being synchronizable or individually controllable to allow directional control of the truck by adapting the speed of each wheel, or the system may control both wheels depending on the configuration of the wheeled vehicle.

[0026] according to Figure 1 The motorized control system of the first example embodiment shown in the figure comprises an electronic control system for controlling the motor, the electronic control system comprising a main power supply device 4, the main power supply device supplies power to power half-bridges 2a, 2b, 2c, the power half-bridges supply power to the phases of the motor and are provided with an upper arm equipped with a first electronic switch 21a, 21b, 21c and a lower arm equipped with a second electronic switch 22a, 22b, 22c, the electronic control system further comprising a programmable computer 3, the programmable computer being used to control the first and second electronic switches by means of a control output 3a for the electronic switches.

[0027] More specifically, the system is composed of at least the following:

[0028] a.-Three-phase brushless DC motor (BLDC) 1;

[0029] b. - an electronic system having three power half-bridges 2a, 2b, 2c, i.e. six MOSFET or IGBT electronic power switches, with 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;

[0030] c.- a programmable computer 3, the programmable computer being used to control the six switches independently of each other;

[0031] d.- A main power source internal or external to the system, such as a battery4.

[0032] The motorized control system may be connected to a computerized parameterization tool, such as an external controller 5 or a laptop or tablet 5a, via a communication link 6, which may be wired or wireless.

[0033] The system is not limited to the illustrated three-phase configuration or to a configuration with a single switch on a branch of a half-bridge, but may include a greater number of phases and parallel switches on a branch, depending on the electrical power of the motor being controlled.

[0034] In this configuration, the computer controls the electronic switches of the three half-bridges in sequence to create a rotating electric field that turns the motor. In addition to sequential control, according to the present disclosure, the computer is also configured to control the switches in two different ways to produce different behaviors in the motor:

[0035] a.- Open the six switches to allow the motor to rotate freely without generating current in the phases, a mode called "freewheel";

[0036] b.- Close the three second electronic switches 22a, 22b, 22c on the lower branch and open the three first electronic switches on the upper branch, which creates a short-circuit current between the three phases of the motor during motor rotation and generates a resistive magnetic force opposite to this rotation. This mode is called "motor braking".

[0037] In this embodiment, if the motor is to be braked, the computer and the half-bridge need to continue to be powered. The control switching of the computer also requires opening the switch on the upper branch when the switch on the lower branch is closed at the same time.

[0038] As stated above, when the mobile vehicle is maneuvered, the control system allows movement to be achieved without actuating motorization and without resistance from the motor in a "freewheel" mode, or conversely, helps to slow or immobilize the vehicle in a "motor brake" mode.

[0039] 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 use phase. Combining modes offers a wide range of options for settings that determine the behavior of the motorized system.

[0040] In order to make different combinations of behaviors accessible to the user of the system, the computerized parameterization tool may 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 method such as infrared. The computerized tool hosts the parameterization software enabling the user to select the desired switching mode according to the usage mode of the motorization.

[0041] When motorization of the wheeled vehicle is actuated by manual control such as control 11, Figure 3 These options, schematically shown in , may be, for example:

[0042] a.- After generating the manual start control M 110, the switches are sequentially operated Seq 140 to drive the motor and traction T of the vehicle;

[0043] b.- due to the opening of the electronic switches on the upper and lower arms after releasing the manual control R 170, switching to freewheeling RL180 to move without electrical transmission, or

[0044] c.- Since the first switch is open and the second switch CCpi is closed after the stop control Stop, switching to motor brake F 160 is performed to help slow down the vehicle by means of electrical braking. This can also be done after releasing the R manual control, instead of switching to freewheeling 180;

[0045] d.- If the vehicle's speed V exceeds a maximum limited speed MAX 120, switching to motor braking F 150 allows the maximum movement speed to be adjusted;

[0046] e.- after releasing the manual control, switching to motor brake F, so as to immobilize the vehicle, then switching to "freewheel" RL 180 at zero speed to enable the vehicle to be moved freely by hand;

[0047] f.-Maintain "motor brake" to park the vehicle.

[0048] Control using the operating mode described above is particularly suitable for industrial trucks with handling assistance. The braking mode provided by shorting the phases saves power because braking is produced by shorting the motor phases rather than by actuating the electrical brakes, and also improves safety by limiting the speed if the vehicle is travelling too fast, and allows the speed of the vehicle to be adjusted, optionally in combination with the freewheeling mode.

[0049] therefore, Figure 3 Schematically showing possible operating modes of a power supply A 100 based on the system, in which the normal sequential control operation Seq 140 of the electronic switches follows the start command M 110 of the vehicle: during the test 120, if the speed of the vehicle has exceeded the maximum speed Max, switching to the short circuit 150 of the electronic switch on the lower arm and opening the switch on the upper arm of the half-bridge to switch to motor braking; during the test 130, after releasing the manual control or the stop command, switching to the short circuit 160 of the electronic switch on the lower arm and opening the switch on the upper arm of the half-bridge to switch to motor braking; after detecting the command to switch to freewheeling 170, release the control or detect zero speed, opening the electronic switches on the lower and upper branches of the half-bridge 180. This allows braking in the presence of the power supply A while keeping the switches of the half-bridge open.

[0050] In the absence or loss of electrical power In the case of 190 , in step 200 , braking by closing the third switch 9 a , 9 b , 9 c and short-circuiting the phases CCbi generates a safe motor brake function FS.

[0051] The computer can control these different modes and switch the power on and off only when power is present. For battery-powered systems, power may be lost during operation if the battery is dead or unable to supply current.

[0052] In this case, loss of braking function upon loss of electrical power may be problematic, especially if the function is activated to keep the vehicle stationary and parked. An uncontrolled loss of braking function may represent a safety risk.

[0053] according to Figure 2 The control system of the embodiment in corresponds to an embodiment comprising a safety circuit that short-circuits the lower branch to guarantee a braking function within a given time after a loss of electrical energy. This system comprises an additional switching circuit 7, optionally parameterizable or programmable, provided with at least one channel 7a for detecting an interruption of the main power supply and comprising a switching element designed to generate a control signal to close, via a control channel 7d, a third switch 9a, 9b, 9c, which is 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 reserve 8 forming a secondary power supply that allows the safety circuit and the control of the switches by 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.

[0054] The energy reserve element can be generated based on an electrochemical capacitor or a supercapacitor, which is supplied by the main power supply 4 through a diode 10 or by a first DC / DC converter, and it is possible to insert a voltage regulator between the energy reserve element 8 and the additional switching circuit 7 of the safety circuit with or without a second DC / DC converter so that the voltage of the charged energy reserve element reaches an acceptable voltage for the additional switching circuit 7, for example 4V to 6V, while the main power supply supplies a voltage of, for example, 12V to 48V when active.

[0055] If greater autonomy of the safety circuit is required, the energy reserve can also be generated by a buffer battery.

[0056] The third switches 9a, 9b, 9c for short-circuiting the phases may be produced by MOSFET transistors which do not need to be dimensioned to control the power and have the advantage of requiring very little current to remain switched on.

[0057] If the system suffers a loss of electrical energy from the main power supply, the safety circuit can trigger the activation of the third switch to the on-mode by means of an additional switching circuit, or this additional switching circuit can automatically trigger the activation after detecting a drop in the main supply voltage. The additional switching circuit 7 can also maintain the voltage for activating the switch to the on-mode by itself, as long as the energy reserve supplies a residual voltage of a few volts. This energy reserve is appropriately dimensioned, for example in terms of storage capacity, to ensure a current for maintaining the on-mode of the third switch for a period of several minutes. This minimum maintenance time is ensured by dimensioning the energy reserve and the type of additional switching circuit.

[0058] This circuit is a MOSFET transistor circuit for low power consumption and is configured to control the third switch to close if the voltage on link 7 a drops below a threshold set by the voltage across the terminals of capacitor 8 .

[0059] This means for maintaining braking ensures that the motor braking function continues for a minimum defined period even in the event of loss or failure of the main power supply and can therefore be considered a safety function, avoiding the conventional need for an electromechanical brake in the absence of current.

[0060] If the wheeled vehicle has to be parked for a long time on sloping ground, this system can optionally be supplemented by a conventional mechanical parking brake.

[0061] In the example shown, the system includes manual control 11 acting on the programmable computer 3. Manual control may be provided in addition to remote control from the external controller 5 via the communication link 6, or may replace remote control in normal operation, the external controller 5 then being used only to program the system.

[0062] exist Figure 3 The power loss is schematically illustrated in step 190 and in step 200 a third switch for short-circuiting the phases of the motor is closed in order to produce an emergency brake.

[0063] The invention is not limited to the examples described above, which are provided merely by way of example, but covers all variants that a person skilled in the art can conceive in the context of the desired protection; in particular, the motor may include more than three phases and the converter may include more than three half-bridges.

Claims

1. A motorized control system for a mobile electric vehicle, comprising at least a three-phase brushless DC motor (1), an electronic control system for controlling the motor, the electronic control system comprising a main power supply device (4), the main power supply device supplies power to a power half-bridge (2a, 2b, 2c), the power half-bridge supplies power to the phases of the motor and is provided with an upper arm equipped with a first electronic switch (21a, 21b, 21c) and a lower arm equipped with a second electronic switch (22a, 22b, 22c), the electronic control system further comprising a programmable computer (3), the programmable computer is used to control the first and second electronic switches by means of a control output (3a) for the electronic switches to generate at least a first drive mode and a second freewheeling mode of the motor, the first drive mode being based on sequential switching control of the switches to create a rotating electric field that causes the motor to rotate, and in the second freewheeling mode, the electronic switches of the power half-bridge are disconnected, 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) connected in parallel with the second electronic switch (22a, 22b, 22c) for short-circuiting the lower arm of the half bridge, the third electronic switch being controlled by an additional switching circuit (7), the additional switching circuit being provided with a detection channel (7a) for detecting an interruption (190) of the main power supply device (4), and / or being provided with a control channel (7b) from the programmable computer and designed to close the third switch to generate the emergency braking, the additional switching circuit being powered by a secondary power supply device (8).

2. The motorized control system for a mobile electric vehicle according to claim 1, characterized in that: The additional switching circuit includes an inhibit output (7c) for the control output of the first and second switches (21a, 21b, 21c, 22a, 22b, 22c) to force the first and second switches into the open position when the third switch is closed.

3. The motorized control system for a mobile electric vehicle according to claim 1 or 2, characterized in that: The secondary power supply (8) is generated by a capacitor or supercapacitor energy storage element.

4. A motorised control system for a mobile electric vehicle according to any one of the preceding claims, characterised in that: The computer includes a configuration programming mode, which includes a traction configuration (140), a freewheeling configuration (150) and a motor braking configuration (160). In the traction configuration, the computer (3) controls the first and second electronic switches (21a, 21b, 21c, 22a, 22b, 22c) based on the sequential control. In the freewheeling configuration, the computer controls the first and second electronic switches (21a, 21b, 21c, 22a, 22b, 22c) to be disconnected. In the motor braking configuration, the computer controls the second electronic switch (22a, 22b, 22c) to be closed simultaneously and controls the first electronic switch (21a, 21b, 21c) to be opened simultaneously in the short-circuit mode of the phase of the motor. The computer has an operating mode designed to implement the configuration according to the control stage of the mobile vehicle.

5. The motorized control system for a mobile electric vehicle according to claim 4, characterized in that: The mobile vehicle is a remotely controlled wheeled vehicle, the configuration being initiated by controls received by the computer from an external controller (5) via a link (6).

6. The motorized control system for a mobile electric vehicle according to claim 4, characterized in that: The vehicle is a wheeled vehicle actuated by manual control (11), and the computer (3) is programmed to initiate the freewheeling configuration (150) after the manual control is released.

7. The motorized control system for a mobile electric vehicle according to claim 4, characterized in that: The vehicle is a wheeled vehicle actuated by manual controls (11), the computer (3) being programmed to activate the motor brake arrangement (160) after the manual controls are released.

8. The motorized control system for a mobile electric vehicle according to claim 4, characterized in that: The vehicle is a wheeled vehicle actuated by manual control (11), and the computer (3) is programmed to activate the motor braking configuration F (150) if the vehicle exceeds a maximum moving speed MAX (120).

9. The motorized control system for a mobile electric vehicle according to claim 8, characterized in that: The computer (3) is programmed to activate the motor braking configuration F (160) after releasing (130) the manual control (11) to immobilize the vehicle and then activate the freewheeling configuration (150) when the vehicle has stopped to enable the vehicle to be moved freely by hand.

10. A motorized control system for moving an electric vehicle according to claim 4, comprising maintaining the motor braking configuration (160) when the motor has stopped in order to park the vehicle.

11. A mobile electric vehicle 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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