MXPA99004010A - Propulsion line decrease control for an electric vehicle - Google Patents

Abstract

An electric motor vehicle includes an electric motor that drives a differential reducer, axes and drive wheels. A control operator produces torque command signals that apply to a controller that orders the application of electrical power to the engine in response to the orders of torsion to achieve the desired torque. The low friction of the electric drive along with the rotational elasticity or imperfect stiffness of the axles can result in poor low-frequency damping movements, especially at low speeds. A decrease arrangement includes a differential circuit coupled between the control operator and the controller to take the difference between the operator-torsion computer and the torque decrease signal. The signal of decrease of torsion. The torque decrease signal is produced by differentiating the speed of the electric motor to produce a signal representative of acceleration-mot

Description

CONTROL OF DECREASE OF PROPULSION LINE FOR AN ELECTRIC VEHICLE The present invention relates to electrically propelled vehicles, and more particularly to those vehicles in which an axle shaft connects the electric motor to the drive wheel. Electric vehicles are becoming very important because they supposedly cause a low environmental impact. When a heavy vehicle, such as a bus or truck, has an electric drive train driving the drive wheel through a speed that reduces differential and one or more axles, it was found that acceleration from low speeds is not even. The analysis regarding acceleration alterations has shown that the rigidity of the axle shaft that joins the torque to the drive wheel is such that the axle tends to undergo a rotational tension, which, together with the low friction of the electric drive train , results in the oscillations of the vehicle speed. The acceleration of electric vehicles is sought. A motor vehicle according to an aspect of the present invention includes a source of electric power and an electric motor that includes an output shaft. The vehicle also contains a control that is an operator-controller source of ordered torsion signals. A control system is coupled to the electric power source, to the electric motor and to receive the torsion command signals to control the motor to produce the ordered torque in the output shaft of the motor. Likewise, the vehicle contains a mechanical gearbox that includes an input shaft coupled to a motor shaft and that also contains an output shaft. The gearbox reduces the speed of the input shaft to produce a lower speed of the output shaft, together with a concomitant increase in the torque of the output shaft. The drive wheel holds and drives the vehicle. A shaft with an elongated shaft is coupled to the drive wheel and to the output shaft of the gearbox, for coupling the torque to the drive wheel from the gearbox by means of these. The axle shaft has a rigidity which, together with the mass of the vehicle, tends to produce a poorly damped movement of the vehicle, which is not desired. An engine speed sensor produces signals representative of engine speed. A differentiation arrangement includes a non-inverted input port coupled to the operator-controller source of ordered torsion signals, and also includes an inverted input port, to deduce signals applied to the inverted input port of the differential arrangement from the signals of torsion ordered, to generate the signals of torsion orders. A decrease signal generator is coupled to the motor speed sensor and the inverted input port of the differentiation arrangement, for coupling to the inverted input port of the differentiation arrangement at least the low frequency components of the acceleration of the motor.

In a particular embodiment of the invention, the gearbox is a differential that includes a second output shaft and the vehicle also contains a second drive wheel and the second shaft couples the second drive wheel to the second output shaft of the differential. The decay signal generator may contain an infinite impulse-response transverse filter that includes an input port coupled to the motor speed sensor to receive the motor speed signals to generate the decay signals. The infinite impulse-response filter may include a delay step that contains an input node coupled to receive the motor speed signals and also includes an output port in which the motor speed delayed signals appear. A first adder circuit that includes an inverted input port and an input port not inverted and an output port where the difference between the signals applied to the inverted and non-inverted input ports is generated. A second adder circuit includes an inverted input port and also includes a non-inverted input port coupled to the output port of the first adder circuit. The second adder circuit also contains an output port in which the decay signals are generated. A first multiplier is coupled to the input node of the delay step and to the non-inverted input port of the first adder circuit, for coupling the motor speed signals from the node to the non-inverted input port of the first adder circuit achieving a particular gain. A second multiplier is coupled to the output port of the delay step and the inverted input port of the second summing circuit, to couple the motor speed signals delayed from the output port of the delay step to the inverted input port of the second circuit adder achieving a second gain. The second gain can equal the particular gain. A feedback step is coupled to the output port of the second adder circuit and to the inverted input port of the first adder circuit. The feedback step contains a delay step and a third multiplier to multiply the feedback signals by laterally moving the feedback step for a third gain. Figure 1 is a simplified drawing of an electric vehicle according to an aspect of the present invention; Figure 2 is a simplified block diagram that includes control parts of the vehicle of Figure 1; Figure 3 is an analytical representation of the control dynamics and propulsion system of the vehicle of Figure 1; and Figure 4 is a detailed block diagram of a particular inclusion of a decrease signal generator of an arrangement of Figure 1. In Figure 1, a vehicle 10 contains a pair of drive wheels 121, 12r, which are found coupled to shaft shaft 141, 14r. The axle shafts 14 are coupled to the axles of the reduction-speed differential 16, which receives the torsion from the output shaft 18s of an electric motor 18. An electric motor 18 receives electric propulsion from a controller represented as a box 20 , which contains a control system. The controller 20 receives the electrical pulse from the battery 22 and produces control signals for the motor in response to the commands of torsion signals produced by a control operator, illustrated as a box 24. Also, the vehicle 10 contains front wheels 261 26r. Figure 2 is a simplified block diagram of a vehicle according to an aspect of the invention. In Figure 2 the elements that correspond to those of Figure 1 are designated by the same reference numbers. In Figure 2, the signals representing the desired torque that are generated by the control operator 24 are applied to the non-inverted input port of a differential or error signal generating circuit. The differential circuit 24 also includes an inverted input port. The differential circuit 24 deduces low-frequency components of the decay torque signal applied to its inverted input port from the ordered torsion signals applied to its non-inverted input port, to generate by means of these torsion-order signals to apply to the controller 20. The controller 20 processes the torque command signals applied to it according to its control rules and produces controlled electrical energy, which is applied to the electric input ports 18p of the motor 18. The motor 18 produces the torsion ordered. As mentioned above, the stiffness of the axle shaft, in the case of low-friction electric propulsion, results in low-ratio variations in vehicle speed. According to the invention, the speed of the motor is measured and a generator of decrease of torsion signals generates diminished torsion signals that are added with the ordered torsion signals, in order to generate in this way corrected torsion order signals that decrease the torsion signals. effects of unwanted variations in speed. In more detail, the engine speed signal generator 212 of Figure 2 contains a shaft position sensor 214 and a differentiator 216, which differentiates the tree position signals from the position sensor 214, to generate this way motor speed signals. The motor speed signals are applied from the motor speed sensor 212 to a torque decrease signal generator 220, which produces low-frequency components of the torque decrease signals in a signal step 228 and applies the signals to an inverted input port of the differential circuit 210. Together with the torsion signal reduction generator 220 a differentiator 222 differentiates the motor speed signals from the speed sensor block 212, to produce signals relating to the acceleration of the motor. The motor acceleration signals are applied to a gain block 224, where they are multiplied by a constant G to produce relative torque decrease signals. Relative torsional decay signals are limited in a low-pass filter 226 at a low frequency, which, for example, may be less than ten Hertz, to produce the low-frequency components of the decrease torque in signal step 228. When operating the vehicle, the low-frequency torsion decrease signals, when deduced from the ordered torsion, produce signals of order of torsion which, when modified by the control rules of the controller 20, commands the motor with a variation torque that compensates for the torsional variations caused by the resonant elements including shaft shafts 141 and 14r. For the purpose of explaining the problem that was discovered in the operation of a vehicle and the nature of the invention in solving the problem, the fact that there are two axles and wheels in the vehicle can be ignored and it is considered as if they were only one. On the other hand, it is necessary to define the two ends of the axis, which are called, for reasons of simplicity, as internal and external ends. The inner end of shaft shaft 141 is illustrated in Figure 2 as 141i and is coupled to one of the shafts (not shown separately) of differential 16. The outer end of shaft shaft 141 is adjacent to drive wheel 121 and designated as 141o. Figure 3 is a simplified diagram of an implementation of a decrease circuit 220 of Figure 2. In Figure 3, the rotational speed signal of the motor Krot is applied to the input port 22oi of the decrease circuit 220, from which is applied to a 312N input node of an impulse-infinity response (MR) side filter generally designated 310. The filter 310 of Figure 3 includes a one-cycle-clock delay or Z "1 element 312, which receives the rotational speed signal from the motor Krot from the node 312N and delays it, to thereby produce a rotational speed signal of the delayed motor Krot at its output port 312. A first adder circuit 314 contains both inverted and inverted input ports. not inverted and also includes an output port or adder that is coupled to the non-inverted input port of a second summing circuit 316. A first multiplier or gain element 318 multiplies the signal of rotational speed of the motor Krot from the node 312N by a predetermined value, represented as the value "a", and applies the multiplied signal to the non-inverted input port of the first adder circuit 314. The first summing circuit 314 deduces the value of the signal applied to its inverted input port from the value of the multiplied signal applied to the non-inverted input port and couples the resulting output signal to the non-inverted input port of the second adder circuit 316. In Figure 3, the signal of rotational speed of the delayed motor Krot at the output port 312o of the delay element 312 is multiplied by a second multiplier or gain element 320 by a predetermined value, which in this example is the same value "a". The multiplied and delayed signal appearing at the output port of the multiplier or gain element 320 is applied to the inverted input port of the summing circuit 316. As mentioned, the summing circuit 316 deduces the value of the signal applied to its port of inverted input from the value applied to its non-inverted input port. The resulting difference signal appears at the output port 316o, and corresponds to the low frequency components of the decrease torque signal which are applied by the decrease signal generator 220 to the step 228 of Figure 2. A step of feedback signal generally designated 322 is coupled between the output port 316o of the summing circuit 316 and the inverted input port of the summing circuit 314. The feedback signal step 322 contains a delay element unit 324 connected in cascade with a 326 multiplier or gain element, which multiplies the signal delayed by a value designated as "b" in Figure 3. The structure represented by Figure 3 corresponds to a software that implements a modality of the invention. Figure 4 is a simplified block diagram that expresses the characteristics of the different parts of the vehicle and their interrelation. In Figure 4, the torsion signals commanded from the source 20 are applied through a differential circuit 210 to the drive train of the electric vehicle 20 that includes the controller and the motor. The drive train 20 produces, in a step illustrated as 410, mechanical torsion Tem representing the torsion of the electric motor. The difference between the motor torque and the load torque T load is produced by the means of the differentiation block designated 412, and the difference that appears in the signal pitch 411 represents the torque applied to the output shaft of the motor. The speed of the Wrot motor shaft resulting from the net torque in the motor shaft is determined by 1 / Js, when J represents the inertia of the motor rotor and the motor shaft and 1 / s represents integration. In Figure 4, the rotational speed Wrot of the motor shaft is applied to a block 416 representing the gear ratio GR of the differential 16 of Figure 1, which reduces the rotational speed or the ratio from Wro to Wax¡ in the inner end 141i of shaft 141. The rotation of inner end 141i of shaft shaft 141 does not result, due to the lack of stiffness of the shaft shaft, in the immediate rotation of the outer end of the shaft. Instead, over time (as represented by the integrator 418), the difference generated by the differentiation block 417, between the rotational speed of the inner end 141i of the shaft of shaft (? AXi) and the rotational speed of the outer end of the shaft tree (the speed of the wheel? wh) results in a change in the twist angle? tw of the shaft at the output of a block 418 representing integration. The torsion angle? Tw when multiplied in block 420 by the stiffness K of the shaft shaft, results in a Tax twist at both ends of the shaft shaft 141. The torque axis Tax is transformed into a linear force Fax when multiply in a block 422 by a factor 1 / ratio relative to the radius of the drive wheel 121. When multiplying the linear force Fax in block 424 by a factor 1 / Ms, when M is the mass of the vehicle and 1 / s is an integration, results in the speed of the vehicle Vve (cuio- The speed VvehicU | 0 of the vehicle, as it is represented in Figure 4 at the output of block 424, when it is multiplied by a factor 1 / RrUeda in the block d feedback 426, produces a rotational wheel speed? Wh which is deduced from the speed of the internal shaft in the differential block 417. The torque of the Tax shaft appearing at the output of block 420 of Figure 4 is transformed through the differential gear. 16 to produce a torsion transformed Tcarga, which is fed back to the construction 412 for its deduction from the torsion of the motor. The oscillation, to which reduction the invention aims, is generated in loop 430 of Figure 4, including blocks 417, 318, 420, 422, 424 and 426. The friction is not shown in Figure 4, because its value is so low in the electric power train, at least in part due to the lack of movement in the crankshaft, pistons and the like of an internal combustion ignition and more especially due to the lack of changeable transmission, which is one of the biggest contributors of friction and therefore decrease. Therefore, the lack of a changeable transmission can make a drive train unstable, which would otherwise be stable in the presence of such a transmission.

The friction B, if it is important enough to represent it in Figure 4, would be represented as a dummy line block 432 connecting the output of the block 414 to another inverted input port of the differential block 412. The friction represented by the block 332, if it is important enough to provide a decrease, a torsional component is supplied to tend to overcome the oscillating component of the torsion current through the block 328. The advance provided by the torsion-reduction signal generator 220 or the Figures 2 and 4 operates by displaying the rotational speed Krot at the motor output and feeding back to the inverted input port of the block 210 a component of the motor acceleration which, when it is transformed through the drive train of the electric vehicle 20 to step 410, supplies a decrease signal that would be supplied by block 432, when there was sufficient friction to supply decrease decrease. In more detail, the derivative block 222 artificially provides an inertia equivalent to J. The oscillatory variation in velocity affects the values of all the variables in loop 430 of Figure 4. Therefore, the oscillation tends to vary the value of the Twist of the Tax axis. This variation in shaft torque is coupled through block 428. If at any specific point the variable value of the shaft torque is increased, the load torque T load at the summing point 412 is also increased. The summing point 412 deduces the increased value of the shaft torque from the torque of the electric motor Tem, to produce a decreasing value of torque at the output of the summing point 412. The decreasing value of torque at the output of the summing point 412 flows to through the inertia of the rotor and the crankshaft of the rotor represented by the block 414, to produce a decreasing value of the rotational speed Kax ,. The decreasing value of the rotational speed returns through block 416 to loop 430 to maintain oscillation and is also coupled to differentiator 222 of decrease signal generator 220. The differentiator generates a negative signal from the decreasing crankshaft speed Krotor-La negative signal from the differentiator 222 is amplified and filtered-low-pass, which does not affect the signal of the signal. The negative decrease signal is applied from LPF 226 to summing circuit 210, where the negative value is deducted from the ordered torsion. The deduction of the negative value increases the ordered torsion at the output of summing circuit 210. The increased ordered torque flows through the drive train represented by block 20 and appears as an increased motor torque in step 410. Increased motor torque in step 410, when encountered together with the load increase torque, results in a substantially constant value of the net torque in the input block 414, notwithstanding the oscillatory nature of the loop 430. The interruption of the variation of Feedback due to oscillation stabilizes the entire vehicle control system.

Other embodiments of the invention will be apparent to a person skilled in the art. For example, the disclosed control system can be implemented as hardware, firmware or software, although the software is preferred if possible. Therefore, the motor vehicle (10) according to the invention includes a source (22) of electric power, an electric motor (18) including an output crankshaft (18s). The vehicle (20) also includes a control which is an operator-controller source (24) of ordered torsion signals. A control system (20) is coupled to the power source (22), the electric motor (18) and to receive torque commands to control the motor (18) to produce the ordered torque on the output crankshaft of the motor (18). The vehicle (10) further contains a mechanical shift case (16) which includes an input crankshaft coupled to the crankshaft (18s) of the engine (18) and also contains an output crankshaft. The gearbox reduces the speed of the input crankshaft to produce a lower output crankshaft speed. A drive wheel (121) supports and propels the vehicle (10). A tree with an elongated shaft (141, 14r) is coupled to the driving wheel (121, 12r) and to the output shaft of the gearbox (16), by means of these coupling the torque to the driving wheel (121, 12r) from the gearbox (16) The axle shaft has a rigidity which, together with the mass of the vehicle (10), tends to produce a movement of poor cushioning of the unwanted vehicle (10). A motor speed sensor (18) produces signals representative of the motor speed (18). A differentiation arrangement (210) includes a non-inverted input port (+) coupled to the source (24) of the operator-controller of ordered torsion signals, and also includes an inverted input port (-), to deduce the signals applied to the inverted input port (-) of the differentiation arrangement (210) from the ordered torsion signals to generate the torsion command signals. A decrease signal generator (220) is coupled to the speed sensor (212) of the motor (18) and to the inverted input port (-) of the differentiation arrangement (210), to couple to the inverted input port (-). ) of the differentiation arrangement (210) at least the low-frequency components of the motor acceleration (18). In a detailed embodiment of the invention, the gearbox (16) is a differential (16) that includes a second output shaft and the vehicle (10) also includes a second drive wheel (12r) and a second shaft (14r) coupling the second drive wheel (12r) to the second output shaft of the differential (16). The decrease signal generator (220) may contain an infinite impulse-response (IIR) side filter (310) which includes an input port (220i) coupled to the speed sensor (212) of the motor (18), for receive the motor speed signals (18) to generate the decrease signals. The infinite impulse-response filter (310) may contain a delay step (312) that includes an input node (312N) coupled to receive the motor speed signals (18), and may also include an output port. (312o) in which the delayed speed signals of the motor (18) appear. A first adder circuit (314) that contains an inverted input port (-) and a non-inverted input port (+) and an output port (314o) in it that generates the difference between the signals applied to the ports of input inverted and not inverted. A second adder circuit (316) contains an inverted input port (-) and also a non-inverted input port (+) coupled to the output port (314o) of the first adder circuit (314). A second summing circuit (316) also includes an output port (316o) in which the decay signals are generated. A first multiplier (318) is coupled to the input node (312N) of the delay step (312) and to the non-inverted input port (+) of the first adder circuit (314), to couple the motor speed signals (18). ) from the node (312N) to the non-inverted input port (+) of the first adder circuit (314) obtaining a particular gain (a). A second multiplier (320) is coupled to the output port (312o) of the delay step (312) and the inverted input port (-) of the second adder circuit (316), to couple the delayed motor speed signals (18). ) from the output port (312o) of the delay step (312) to the inverted input port (-) of the second adder circuit (316) obtaining a second gain (a). The second gain can equal the particular gain. A feedback step (322) is coupled to the output port (316o) of the second adder circuit (316) and to the inverted input port (-) of the first adder circuit (314).

The feedback step (322) includes a delay step (324) and a third multiplier (326) for multiplying feedback signals of lateral movement in the feedback step (322) by the third gain.

Claims (5)

1. - A motor vehicle, containing: a source of electrical energy; an electric motor that contains an output shaft; an operator-controller source of ordered torsion signals; a control system coupled to said strong electric power, to said electric motor and to receive torsion-order signals to control said motor to produce said ordered torsion in said output shaft of said motor; a mechanical gearbox containing an input shaft coupled to said shaft of said motor and also containing an output shaft to reduce the input speed of the shaft to produce a lower speed of the output shaft, together with a concomitant increase in the torsion of the output shaft; a driving wheel to support and propel said vehicle; an elongated axle shaft coupled to said driving wheel and said output shaft of said gearbox, for in this way coupling the torque to said driving wheel from said gearbox, said shaft having a stiffness that together with the mass of said vehicle tends to produce a movement of poor cushioning that is not desired; motor speed sensing means for producing signals representative of the speed of said motor: differentiation means including a non-inverted input port coupled to said operator-controller source of ordered torsion signals and also includes an inverted input port to deduce signals applied to said inverted input port from said ordered torsion signals to generate said torque order signals; and decreasing signals generating means coupled to said means of measuring the motor speed and said inverted input port of said differentiation means, for coupling said inverted input port of said differentiation means to at least the lowering components. frequency of engine acceleration.

2. A vehicle according to claim 1, wherein said gearbox is a differential that includes a second output shaft and said vehicle further contains a second drive wheel and a second shaft coupling said second drive wheel to said second output tree of said differential.

3. A vehicle according to claim 1, wherein said decay signal generates means including: an infinite impulse-response transverse filter containing an input port coupled to said motor speed measurement means for receiving said motor speed signals to generate said decay signals.

4. A vehicle according to claim 3, wherein said infinite-impulse response filter contains: a delay step that includes an input node coupled to receive said motor speed signals and that also includes a port of input in which the delayed speed signals of the motor appear; a first adder circuit that includes an inverted input port and a non-inverted input port and an output port in which the difference between the signals applied to said inverted and non-inverted input ports is generated; a second adder circuit including an inverted input port and also including a non-inverted input port coupled to said output port of the first adder circuit and also including an input port in which said decrease signals are generated; a first multiplier coupled to said input node of said delay step and said non-inverted input port of said first adder circuit for coupling said motor speed signals from said node to said non-inverted input port of said first adder circuit obtaining a particular gain; a second multiplier coupled to said output port of said delay step and said inverted input port of said second summing circuit for coupling said delayed motor speed signals from said output port of said delay step to said inverted input port of said second adder circuit obtaining a second gain, and a feedback step coupled to said output port of said second summing circuit and said inverted input port of said first summing circuit, said feedback step includes a delay step and a third multiplier to multiply the feedback signals of movement side of said feedback step for a third gain.

5. A vehicle according to claim 4, wherein said gain equals said particular gain.