RU2513360C1 - Multiple-motor electric carrier and method of its control (versions) - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: set of invention relates to automotive industry. Proposed carrier comprises power regenerator, motion speed and moment setter, braking moment setter, motion mode selector, motors, inverter, top level control system (TLCS), consumed current transducers of inverters and load distribution system (LDS). LDS outputs are connected to outputs of inverters and current transducers. Signals of setting the factors of load distribution between drive wheels are fed to LDS inputs. LDS outputs are connected to inputs of inverter speed setting. In compliance with first version, control method consists in determination of load mean current and drive actual current departure magnitude, generation of speed setting correction signal to set required distribution of torques at drive wheels via communication link proceeding from obtained drive current departure magnitude. In compliance with second version, control method consists in determination of load mean current and drive actual current departure magnitude, generation of speed setting correction signal to set required distribution of torques at drive wheels via communication link proceeding from obtained drive current departure magnitude.

EFFECT: better operating performances.

7 cl, 6 dwg

Description

FIELD OF TECHNOLOGY

The present invention relates to the field of electric vehicles, in particular to multi-engine electric vehicles containing at least two driving wheels, each of which is driven by an independent electric drive.

BACKGROUND

When two independent electric drives are used in a multi-engine electric vehicle on the same axis or on each axis, the problem of rational control of independent electric drives arises.

Known electric vehicle (WO 01/54939 A2, BK 26/00), containing at least two electrically driven wheels and a method for coordinating these at least two drive wheels using an external control device. In this case, the control system of the wheel carries out its installation in the driving position or in the driven position. The choice of installation is carried out by an external control device, for example, based on the speed of the wheel - the wheel with the highest rotation speed is selected as the master, the rest as slaves. A disadvantage of the known solution is the possibility of uneven loading of the drive wheels and the inability to provide the required load distribution in the speed loop.

Figure 1 presents an example of a known implementation of the structure of the Converter with a separate task level current limitation in motor and braking modes, i.e. with separate task of motor and braking moments.

The electric drive of each of the drive wheels contains a speed controller (PC) (usually a proportional-integral controller), a unit for separately setting the current limiting value (URZT) in braking (It) and motor (It) modes; a current loop (CT) containing a power amplifier (not shown); and an electromechanical link of an electric drive with an electromechanical time constant Tm; and the input of the speed controller receives the difference between the reference signal and the feedback signal for speed ω _ass and ω _OS ; the output of the speed controller is connected to the input of the URZT, the other inputs of which receive the reference signals Itot and Itod; the output of URZT, which generates the signal for the current current setting I to the axis minus the current feedback signal Ioc, is fed to the input of the current loop, the output of which, which is the drive current, is supplied with the static current Ic (a measure of the moment of static resistance of the drive) to the input of the electromechanical link whose output is the angular velocity of the electric drive ω.

In a speed-locked system (speed loop) in steady state, the drive current is determined by part of the total resistance moment associated with a given wheel.

When the steering wheel is in a neutral position, the plane of rotation of the wheels driven by electric motors, that is, the motor-wheels (MK), should be parallel to the longitudinal axis of the MEAT (multi-engine electric vehicle) and the axis of movement. The coefficients of friction of tires with lateral shear are significantly (5-10 times) greater than the coefficients of rolling friction. This contributes to self-alignment of the direction of motion and angular velocities. With a slight difference in the speeds of the motor wheels, a moment arises that tends to turn the multi-engine electric vehicle. But in the absence of slippage, the wheels are connected through the roadway and this is accompanied by a lateral shift of the motor wheels, which is counteracted by the arising forces that prevent lateral sliding and turning. At the same time, the speed of the motor wheels is forcibly aligned.

However, an undesirable inequality of the torques and currents of the motor wheels may occur. The same inequality can occur due to the scatter of engine parameters, the non-identical road surfaces for different motor wheels, due to inaccurate speed settings, redistribution of axle loads or changes in the parameters of the mechanical part. Uneven load distribution of electric drives can be caused by the difference in the normal component of the load on the wheels, both static - due to asymmetric loading of the vehicle, and dynamic - along the axes during acceleration and braking and on the sides - when turning. An example of changing the parameters of the mechanical part can be a change in the radius of the wheel, which depends on a number of different factors: tire pressure, normal component of the load on the wheel, the magnitude of the transmitted torque, temperature, etc. The dependence of the actual radius Rk on the torque supplied to the wheel Mk has been experimentally established. . In the source of V.A. Patrushov "Cars and Trains" (New technologies for research of rolling and air resistance. 351 pp. M .: Torus PRESS, 2008.) the experimental linear dependence of the radius of the wheel on the magnitude of the transmitted moment is given, when accelerating, the radius decreases when braking increases.

With the static characteristics of electric drives closed in speed (in the speed loop), the load distribution is directly proportional to the rigidity of the mechanical characteristics: the stiffer the mechanical characteristic, the greater part of the load is taken by the electric drive (Fig. 2A). If there are job errors and the same mechanical characteristics, the electric drive with a larger speed task takes on a large load (Fig. 2B).

In the METS, in the absence of slippage, the wheels are connected through the roadway by the equality of linear speeds (in rectilinear motion). At the same time, the coordinate of the speed feedback in the electric drive is the angular frequency of rotation of the wheel. The coupling coefficient between these values (the angular frequency of rotation and the linear velocity of the tire surface point) is the radius of the wheel, which, as mentioned above, depends on the tire pressure, the normal component of the load on the wheel, the magnitude of the transmitted moment, temperature, etc.

Changing the specified coefficient (radius) with the same speed reference will lead to a shift in the electromechanical characteristics (Fig.2B) and load redistribution. Long-term inequality of motor currents can lead to overheating of one motor-wheel due to underloading of another.

Evaluation of the effect of uneven load distribution over the wheels on the level of losses in the METS electrical system can be carried out using an ETS with two drive wheels as an example. With a uniform load distribution M1 = M2 = Ms / 2, with an extremely uneven load distribution M1 = 0; M2 = Mc, where:

M1 and M2 - moments of MK;

Mc is the total moment of resistance of the METS.

Figure 3 shows a typical dependence of the efficiency (η) of the electric drive on the developed moment at a constant angular velocity ω. In the first case, the level of losses in the system is Rpot1 = 2 × ω × (Ms / 2) × (1-η1) / η1; in the second case, the level of losses in the system Rpot2 = ω × Ms × (1-η2) / η2.

In our example: Rpot1 = 0.11 × ω × Ms; Rpot2 = 0.25 × ω × Ms, i.e. in the second case, with an extremely uneven load distribution, the losses in the system are more than two times greater, and this is without taking into account additional losses from the turning moment that occurs in the second case.

In some cases, there may be a need for a different, non-uniform distribution of the load due to a change in the slope of the road, the quality of the supporting surface, driving mode, etc. (A.M. Saikin, I.A. Pliev, G.V. Korshunov, A.V. Arkhipov. On optimizing power distribution along the axles and wheels of four-wheel drive vehicles depending on road conditions. Automotive Engineers Magazine No. 3 (68) 2011 p. 34-37).

Closest to the technical nature of this invention is the "Electric vehicle" disclosed in the patent of Russian Federation 2413 635. The known device is a multi-engine electric vehicle containing an autonomous power source or connected to an external power source; energy recuperator; body for setting the speed (moment) of movement (gas pedal); body for setting the braking moment (brake pedal); switch of the choice of the mode of movement (forward, backward, stop, free wheeling); two or four drive electric motors connected respectively with two or four drive wheels of the vehicle through or without mechanical transmission; two or four reversing converters for regulating the speed (moment) of the drive motors; a steering wheel rotation sensor and a top-level control system (SUVU), the aforementioned driving and braking torque setting organs and a mode selection switch being connected to the SUVU inputs, and the SUVU outputs connected to the control inputs of the reversing converters, which are made reversible, with a separate setting of the current limit level in motor and braking modes, i.e. with separate assignment of motor and braking moments; in addition, the outputs of reversing converters that carry information about the current and speed of the drive motors are connected to the inputs of the SUVU, and the SUVU generates the speed (moment) of the drive motors taking into account the position of the steering wheel and gas and brake pedals.

A disadvantage of the known solution is the possibility of uneven loading of the drive wheels and the inability to provide the required load distribution in the speed loop.

SUMMARY OF THE INVENTION

The aim of the present invention is to increase (improve) the operational characteristics of a multi-engine electric vehicle, such as maneuverability, controllability, stability, driving comfort, economy of regulation. These goals are achieved by an electric vehicle made in accordance with the present invention, and a method for controlling it.

In accordance with the present invention, there is provided a multi-engine electric vehicle comprising an autonomous power source or connected to an external power source; energy recuperator; body for setting the speed and moment of movement; body for setting the braking moment; motion mode selection switch; two or four drive electric motors connected respectively to two or four wheels of the vehicle; two or four reversing converters for regulating the speed and moment of the drive electric motors and a top-level control system (SUVU), the aforementioned organs for setting the moment and speed of movement and braking torque and the switch for selecting the driving mode are connected to the inputs of the SUVU, and the outputs of the SUVU are connected to the control inputs of the reverse converters, which are made reversible, with a separate task of the level of current limitation in motor and braking modes; characterized in that it additionally contains sensors for the current consumption of reversing converters and a load sharing system (RNS), and outputs of reversing converters carrying information about the current of the drive motors, outputs of current sensors carrying information about the current consumption of the reversing converters from the power source are connected to the inputs of the RNL , and the inputs of the NRC receives signals for setting the coefficients of the required load distribution between the drive wheels, and the outputs of the NRC are connected to the inputs the speed of reversing converters.

In addition, the outputs of reversing converters carrying information about the current and speed of the drive motors can be additionally connected to the inputs of the SUVU; moreover, the SUVU is configured to set the speed and moment of the drive electric motors taking into account the position of the speed setting organ and the moment of movement and the setting element of the braking moment.

The load distribution system (RNS) may include an input adder connected to the outputs of the reversing converters that carry information about the current of the drive motors, and the output of the input adder is connected to a common point of the nodes for setting the coefficients of the required distribution of moments of the drive wheels through the divider by the number of drive wheels, and output adders moreover, the outputs of the nodes for setting the coefficients of the required distribution of moments of the driving wheels are connected to the direct inputs of the output adders, and the output is connected to the inverse inputs The outputs of the reversing converters are connected to the adders, carrying information about the current of the drive electric motors, and the outputs of these output adders are connected to the speed reference inputs of the reversing converters through a communication link.

In another embodiment of the invention, the load sharing system (RNS) may include an input adder connected to the outputs of current sensors carrying information about the current consumption of the reversing converters, the output of the input adder being connected to a common point of the nodes for setting the coefficients of the required power distribution of the drive wheels through a divider by the number driving wheels, and output adders, and outputs of nodes for setting the coefficients of the required distribution of moments are connected to the direct inputs of the output adders the drive wheels, and the outputs of the current sensors carrying information about the current consumption of the reversing converters are connected to the inverse inputs of the output adders, the outputs of these output adders being connected to the speed reference inputs of the reversing converters via a communication link.

A control method for a multi-engine electric vehicle in accordance with one embodiment of the present invention corresponding to the first embodiment of the RNC includes determining the average load current by adding signals proportional to the currents of the electric drives of the wheels and dividing the resulting amount by the number of driving wheels; determining the deviation of the current drive current by subtracting from the value of the average load current, multiplied by the coefficient of the required distribution of moments of the drive wheels, the value of the current drive current;

generating a speed reference correction signal providing the required distribution of driving wheel moments through the communication link based on the obtained value of the current drive current deviation.

A method of controlling a multi-engine electric vehicle in accordance with another embodiment of the RNC includes determining the average current consumption by adding signals proportional to the current consumption of the drives, and dividing the resulting amount by the number of drive wheels; determination of the deviation of the current drive current consumption by subtracting the average current consumption multiplied by the coefficient of the required power distribution of the drive wheels from the value of the current drive current consumption; generating a speed reference correction signal providing the required power distribution of the drive wheels through the communication link based on the obtained deviation of the current drive current consumption.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will be apparent from its subsequent description and drawings, in which:

figure 1 shows the structural diagram of the Converter with separate task levels of current limitation, known from the prior art;

on figa shows the load distribution with the static characteristics of electric drives, closed in speed;

on figb shows the load distribution in the presence of job errors and the same mechanical characteristics;

figure 3 shows an exemplary curve of the dependence of the efficiency of the drive from the moment at a constant speed;

figure 4 shows a structural diagram of a multi-engine electric vehicle in accordance with the present invention;

5 is a structural diagram of a load balancing system in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The distribution (for example, alignment) of the currents of the motor wheels can be carried out by lowering the electromechanical characteristics of a more loaded drive and raising the characteristics of a less loaded (Fig.2B). At the same time, to ensure the stability of the system, the following conditions must be met:

M1 + M2 = const;

I1 × Cm1 + I2 × Cm2 = I1 '× Cm1 + I2' × Cm2, where:

I1 and I2 - currents of the motor-wheels of correction;

I1 'and I2'- currents of motor-wheels after correction;

Cm1 and Cm2 are the coefficients of the moments of the motor wheels.

Lowering and raising of the electromechanical characteristics is achieved by a corresponding change in the signals for setting the speed of the motor-wheels.

Figure 4 presents the structural diagram of a multi-engine electric vehicle in accordance with the present invention. A multi-engine electric vehicle contains an autonomous power source 1, an energy recuperator 2, a gas pedal 3 (speed and torque setting body), a brake pedal 4 (braking torque setting body), and a driving mode select switch 5 that is configured to switch forward modes "," back "," stop "and" free play ". An electric vehicle may also be connected to an external power source.

An electric vehicle may comprise two or four drive electric motors connected to two or four wheels of the vehicle, respectively, with or without mechanical transmission, as well as two or four reversing converters, respectively, for controlling the speed and torque of the drive motors.

As shown in FIG. 4, the electric vehicle comprises four motor wheels 7, that is, four drive electric motors connected to four wheels of the vehicle, and four reversing converters 6 for controlling the speed and torque of the drive motors. The electric vehicle also contains a top-level control system 8 (SUVU), to the inputs of which a gas pedal 3, a brake pedal 4, and a driving mode select switch 5 are connected. The outputs of the SUVU 8 are connected to the control inputs of the reversing converters 6, which are reversible, with separate setting of the current limiting level in the motor and brake modes, i.e. with separate task of motor and braking moments. The outputs of the reversing converters 6, carrying information about the current and speed of the drive motors, are also connected to the inputs of the SUVU 8, and the SUVU 8 generates a task for the speed and moment of the drive motors, taking into account the position of the gas and brake pedals.

In the electric vehicle, the current sensors of consumption of the reversing converters 6 and the load distribution system 9 (RNC) are provided. The outputs of the reversing converters 6, carrying information about the current of the drive motors, the outputs of the current sensors 10, carrying information about the current consumption of the reversing converters 6 from the power supply 1 are connected to the inputs of the SRN 9, and the outputs of the SRN 9 are connected to the speed setting inputs of the reversing converters 6. the inputs of the SRN 9 receives signals for setting the coefficients of the required load distribution between the wheels.

Let us further consider the proposed solution using an electric vehicle with two drive wheels as an example. 5 shows a block diagram of a load balancing system 9.

A control method for an electric vehicle containing the load distribution system shown in FIG. 5 includes determining the average load current ΣI / 2 (or the average current consumption of drives ΣIn / 2) by adding signals proportional to the currents of electric drives of the wheels Ii (or the currents of consumption of drives ΣI (ΣIn ), an input adder 11, and dividing the resulting sum ΣI (ΣIn) by the number of driving wheels by a divider 12. In nodes 13, the coefficients of the required distribution of moments (powers) of the driving wheels are multiplied by the mean t Then we determine the deviation of the current drive current ΔIi (current drive current consumption ΔIni) by subtracting the output adders 14 of the current drive current (current drive current consumption ΔIni) from the average current multiplied by the coefficient the required distribution of moments (powers) of the drive wheels The obtained deviation of the current drive current ΔIi (current drive current consumption ΔIni) through the communication link ЗС 15 generates a signal rektirovki Δωi reference speed, providing the required distribution moments (capacity) of the drive wheels. The type (proportional or proportional-integral) and AP parameters are determined by the level of requirements for accuracy and speed of the load distribution system.

Consider the operation of RNS with equal coefficients (K1 = K2 = 1) and input signals proportional to the current (moment) of the reversing converters. When a difference in the load of electric drives of motor-wheels appears due to the uneven load of the wheels due to the unevenness of the static or dynamic load, the pressure difference in the tires, etc. The NRC adjusts the speed reference value of each drive accordingly and thus contributes to the alignment of the axle load. When turning METS due to steering wheel rotation and changes in wheel speeds in accordance with the geometry of the chassis, the following occurs:

- the speed of the outer (outer) wheel increases, the speed of the inner (with a smaller turning radius) wheel remains unchanged;

- the current (moment) of the outer wheel decreases, the current (moment) of the inner wheel increases;

- RNC adjusts the speed reference of the drives, increasing the speed reference for the outer wheel and decreasing the speed reference for the inner wheel, thereby equalizing the load of the motor wheels and ensuring equal currents (moments).

Consider the operation of the RNS at different coefficients (K1 = 4/3, K2 = 2/3) and input signals proportional to the current (moment) of the reversing converters. When a difference in the load of electric drives of motor-wheels appears due to the uneven load of the wheels due to the unevenness of the static or dynamic load, the pressure difference in the tires, etc. The RNC accordingly corrects the magnitude of the speed reference of each electric drive and thus ensures the distribution of currents (moments) in a ratio of 2: 1. When turning METS due to the rotation of the steering wheel also produce the distribution of currents (moments) in accordance with a given ratio.

The sum of the distribution coefficients should be equal to the number of drives adjusted by the RNC.

Consider the operation of RNS with equal coefficients (K1 = K2 = 1) and input signals proportional to the current consumption of reversing converters. When a difference in the load of electric drives of motor-wheels appears due to the uneven load of the wheels due to the unevenness of the static or dynamic load, the pressure difference in the tires, etc. The NRC adjusts the magnitude of the speed reference for each drive accordingly and thus helps to equalize the drive currents, thereby ensuring equal power consumption. With the proximity of the modes of motor-wheels in terms of speed, it can be concluded that the efficiency values of reversing converters are close, and therefore the power developed by the motor-wheels is equal. A similar situation is observed when turning METS due to the rotation of the steering wheel.

Thus, the proposed METS solution and its control method allows you to abandon the steering wheel position sensor and automatically adjust the speed of the wheels when turning with a given distribution of moments (powers).

Claims (7)

1. A multi-engine electric vehicle containing an autonomous power source or connected to an external power source, an energy recuperator, a speed and torque setting body, a braking torque setting body, a driving mode selector, two or four drive electric motors associated with two or four wheels, respectively a vehicle, two or four reversing converters for controlling the speed and moment of drive electric motors and a top-level control system I (SUVU), and the mentioned bodies for setting the moment and speed of movement and the moment of braking and the switch for selecting the driving mode are connected to the inputs of the SUVU, and the outputs of the SUVU are connected to the control inputs of the reversing converters, which are reversible, with a separate setting of the current limitation level in the motor and brake modes , characterized in that it additionally contains sensors of current consumption of reversing converters and a load sharing system (RNS), and outputs of reversible are connected to the inputs of RN converters that carry information about the current of the drive motors, outputs of current sensors that carry information about the current consumption of the reversing converters from the power source, and the signals of the task of the coefficients of the required load distribution between the drive wheels are fed to the inputs of the SRN, and the outputs of the SRN are connected to the inputs of the speed setting of the reversing converters. 2. The multi-engine electric vehicle according to claim 1, characterized in that the outputs of the reversing converters carrying information about the current and speed of the drive motors are additionally connected to the inputs of the SUVU, the SUVU being configured to set the speed and torque of the drive motors taking into account the position of the speed setting body and the moment of movement and the body to set the moment of braking. 3. A multi-engine electric vehicle according to any one of claims 1 or 2, characterized in that the sum of the coefficients of the required load distribution between the drive wheels is equal to the number of drive wheels. 4. The multi-engine electric vehicle according to claim 3, characterized in that the NRC contains an input adder connected to the outputs of the reversing converters carrying information about the current of the drive motors, the output of the input adder being connected to a common point of the nodes for setting the coefficients of the required distribution of moments of the drive wheels through the divider the number of drive wheels and the output adders, and the outputs of the nodes for setting the coefficients of the required distribution of moments are connected to the direct inputs of the output adders driving wheels, and the inverted inputs of the output adders are connected to the outputs of the reversing converters, carrying information about the current of the drive electric motors, and the outputs of these output adders are connected to the speed reference inputs of the reversing converters through the communication link. 5. The multi-engine electric vehicle according to claim 3, characterized in that the SRN comprises an input adder connected to outputs of current sensors carrying information about the current consumption of the reversing converters, the output of the input adder being connected to a common point of the nodes for setting the coefficients of the required power distribution of the drive wheels through divider by the number of driving wheels, and output adders, and outputs of nodes for setting the coefficients of the required distribution of moments are connected to the direct inputs of the output adders uschih wheels, and to output inverted inputs of the adders are connected outputs of the current sensors, carrying information about current consumption of reversible converters, and outputs the output of said adders are connected to the inputs of inverters job reverse rate through the communication link. 6. The method of controlling a multi-engine electric vehicle according to claim 4, comprising determining the average load current by adding signals proportional to the currents of the electric drives of the wheels, and dividing the resulting amount by the number of driving wheels, determining the magnitude of the deviation of the current drive current by subtracting from the value of the average load current multiplied the coefficient of the required distribution of moments of the driving wheels, the current value of the drive, the formation of a signal for adjusting the speed reference, providing the required e distribution points of the drive wheels, via a communication link based on the obtained amount of deviation of the current drive current. 7. The method of controlling a multi-engine electric vehicle according to claim 5, including determining the average current consumption by adding signals proportional to the current consumption of the drives, and dividing the amount by the number of drive wheels, determining the deviation of the current drive current consumption by subtracting the average current consumption from the value, multiplied by the coefficient of the required power distribution of the drive wheels, the current consumption current of the drive, the formation of the signal adjusting the speed reference growth, providing the required power distribution of the drive wheels through the communication link based on the obtained deviation of the current drive current consumption.

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