MXPA99002526A - Proportional internal regulator of two-dimensional variable limit for the current controller in the sync structure - Google Patents

Abstract

A controller (400) for a variable speed induction motor (498) includes a field-oriented control (410, 476) which in the feedback arrangement (402) detects the motor parameters to form the field error signals and of torque. The field error signals are processed by a first limited state processor PI (490a), which individually limits the magnitude of the proportional component of the field voltage to no more than the bus voltage. The field error signals are also processed by a limited state integrator (426a) which limits the integral component of the field voltage to the difference between the proportional component and bus voltage. A first adder (432a) adds the proportional and integral components to generate the field voltage command. The torque error signals are processed by a limited-state PI processor (490b) which individually limits the proportional component of the torque voltage to a value no greater than the available bus voltage, after which given the preference to the first PI processor. The integral component of the torque voltage command is generated by a second state-limited integrator (426b) which limits the integral component of the torque voltage command so that the torque voltage command does not exceeds the available busbar voltage. A second summing circuit (432b) adds the proportional and integral components of the torque voltage command. The commands of field voltage and motor torque desired, and a feedback circuit forces the motor current to follow the values of command

Description

PROPORTIONAL INTERNAL REGULATOR WITH B-DIMENSIONAL VARIABLE LIMIT FOR THE CURRENT CONTROLLER IN THE SYNCHRONOUS STRUCTURE This invention relates generally to charge controllers, and more specifically, to controllers useful for controlling induction motors. Electric vehicles are becoming commercially important. Such vehicles include a traction battery and a traction motor. Some current proposals use a hybrid concept, in which an additional power source, such as a motor / generator, is used to improve the range of the vehicle by recharging the traction battery during operation. Since the vehicle is powered by a direct voltage traction battery, some of these vehicles use direct voltage motors. The direct current motor has brushes, which They are a point of wear. The direct current brushless motor is a permanent magnet motor, which is energized by alternating voltages. The induction motor is more robust, and can be less expensive to build in relatively high energy output than brushless direct current motors. The induction requires alternating voltages of variable frequency and variable voltage for a complete control. Some induction motor controllers use voltage / frequency (V / F) controllers, but the control is less complete than the Oriented Control Field (FOC), and it is difficult to cause the induction motor to rotate above the "nominal" motor speed, which is the no-load speed at which the motor will rotate when the specified drive voltage is applied. The induction motor can rotate commonly at speeds of rotation much greater than the nominal one. It is desirable to connect the induction drive motor to the drive wheels by a fixed mechanism relationship, in order to avoid the cost and weight of a transmission. When the traction motor is directly connected to the drive wheels, the considerations that determine the fixed mechanism relationship can be understood by considering as an example, an induction motor having a nominal speed of 4000 RPM, and having a speed of maximum possible rotation (rupture) of 16000 RPM. On the other hand, if it were desired to limit the maximum speed of the engine to 4000 RPM, and that the desired maximum speed of the vehicle was 104.58 Km / h, the reduction ratio of the mechanism would be four times less than if the maximum speed had been selected as 16,000 RPM. In other words, the mechanism reduction ratio that gives 104.58 Km / h at 16000 RPM is greater than that required for 104.58 Km / h at 4000 RPM. In turn, this larger mechanism reduction ratio advantageously produces a greater torque throughout the speed range. Therefore, the induction motor should be operated near the rated bus voltage. Figure 1 is a simplified plane 1 of the speed of the motor ? against the field strength? characteristic of an induction motor. In Figure 1, plane 1 includes a portion 2 that is constant at a flow value of? N? Minai from zero to the nominal motor speed? Nmina-This portion of the plane represents a region of operation in which the motor it is not limited by the applied bus voltage, but rather by other considerations such as the maximum winding current. Region 3 of plane 1 is a region in the engine speed that is greater than the nominal speed? Nomina ?, in which the counter electromotive force (EMF) is given by which indicates that at the rated speed, the counter electromotive force is equal to the specified bus voltage. The engine speed designated? Max represents the speed at which the centrifugal forces are expected to cause the rotor to disintegrate, and therefore represent an absolute maximum upper speed limit. At speeds? greater than the nominal speed? nom¡nai, the counter electromotive force exceeds the bus voltage, while maintaining the flow field. Thus, the intensity of the field must be reduced to operate at speeds above the nominal, in order to reduce the counter electromotive force, so that there is some potential difference between the bus voltage and the counter electromotive force to produce current the motor. Nevertheless, the reduction of the flow also reduces the torque. In order to maintain the maximum amount of torque in the range of rated speed motor speeds at the maximum allowed selected speed (less than? Max, the counter electromotive force must be maintained just below the busbar voltage. that, the motor always operates near the busbar voltage limit in the region above the nominal speed.As a result, the stability can be compromised during the periods in which the controller demands the application of more motor voltage than the maximum bus voltage. The limited-state integral proportional regulators are known for use in control circuits, as described, for example, in "Non-linear Algorithms for Fast and Robust Control of Electric Drive" by Dusan Borojeviv, PHD dissertation, 1986, Virginia Polytechnic Institute, Blackburg State University, Virginia. Figure 2 is a simplified block diagram of a control system 10 in accordance with the prior art. In Figure 2, the reference signal or user command is applied via a terminal 12 to a non-inverting (+) input port 14i1 of an error signal generator 14. It should be understood that the signals described herein they represent the values that their names suggest, so that, for example, a motor field voltage command signal represents, either directly, or, by a constant of proportionality, the actual field value, or the field current, or the corresponding values of the field itself or of the current produced by the field measured in other reference systems, so that signal processing can be described in terms of the representative signals or the values that the signals represent. The error signal generator 14 of FIG. 2 subtracts from the reference signal a feedback signal representing the controlled variable that is applied to the inverter input port (14), to produce the system error signal. The error signal is applied to the first and second multipliers 16 and 18, respectively. The first multiplier 16 multiplies the error signal by a constant Kp, as is known in the art, to produce a proportional command component at its output port 16o. The proportional command component is applied to an input port 20i of a limiter 20. The limiter 20 limits the range of the proportional command to be between the maximum and minimum values applied to its upper limit port 20ul and the lower limit port 2011, respectively. The signal or upper limit value applied to the upper limit port 20ul of the limiter 20 is produced by the maximum command source 22, and the signal or lower limit value applied to the lower limit input port 2011 is produced by the source of minimum command 24. The limiter 20 produces a limited proportional command signal at its 20th output port. The second multiplier 18 of Figure 2 multiplies, by a constant K, the error signal applied to its input port 18i, in order to produce a signal at its output port 18 which, due to the action of the feedback circuit as described below, represents the first derivative of the integral component of the limited integrated command. The limited state integrator 26 integrates the signal from the output port 18o of the multiplier 18, to produce an integrated signal that is limited by limiting the state of integration of the limiter 26. More particularly, the state of integration of the limited state integrator 26 is limited to be below a higher value applied to its upper limit port 26ul and to be above a lower value applied to its lower limit port 26II. The upper limit signal applied to the. upper limit port 26ul of the limited state integrator 26 is represented by the output signal of a differentiating or subtraction circuit 28. The differentiating circuit 28 takes the difference between the limited proportional component of the command, the output port 20o of the limiter 20, and the maximum command value of the source 22. Likewise, the lower limit signal applied to the lower limit port 26II of the limited state integrator 26 is produced by a differentiator circuit 30, which takes the limited proportional component of the command signal from the minimum command value produced by the source 24. Thus, the upper integration limit of the integrator 26 is limited to be below the maximum limit set by the differentiator circuit 28, and the lower integration limit of the integrator 26 is limited to be up of the minimum limit established by the differentiator circuit 30. The output at the output port 26o of the limiting integrator 26 is the limited integrated component of the command signal. An adder circuit 32 of Figure 2 adds the limited proportional components and the limited integrated component of the command signals to produce the total command signal to control the plant 34. The plant 34 responds to the command signals to adjust the variable controlled and therefore the feedback signals returning to the inverting input port 14i2 of the error signal generator 14 to close the degenerative feedback circuit. The configuration of Figure 2 has the advantage of, in the presence of a transient input or reference signal, limiting the excess attributable to the slow response of the plant in conjunction with the time constant of the integrator. When the two control limiters were used to control the field and torque components of an induction motor, the control of the motor was unstable in certain modes of operation. Improved induction motor controllers are desired. A system in accordance with the invention uses an energized induction motor of a direct voltage bus bar having a bus voltage. The system includes a field-oriented controller to generate commands of orthogonal torque and flow currents mutually in a structure Synchronous A first error signal generator is coupled to the field-oriented controller, to subtract the feedback field current signals from the flow current command signals, so as to generate field current error signals. A second error signal generator is coupled to the field-oriented controller, to subtract the feedback torque current signals from the torque current command commands, so as to generate torque current error signals. An integral proportional regulator of Variable limit is coupled to the first error signal generator, and responds to the flow current error signal. The first integral variable-range proportional regulator generates commanded flow voltage signals including proportional and integral components, and limits each of the proportional and integral components of the commanded flow voltage to a value such that the sum of the proportional and integral components of the commanded flow voltage is not greater than the available bus voltage. A second integral proportional variable limit controller is coupled to the second error signal generator, and responds to the torque current error signals. The second integral proportional variable limit regulator generates commanded torque voltage signals including proportional and integral components, and limits each of the proportional and integral components of the commanded torque voltage to a selected value so that the magnitude of the the sum of vectors of the commanded flow voltage and the commanded torque voltage shall not be greater than the available bus voltage. A feedback configuration is coupled to detect current in the motor windings, to generate the feedback field current signals and the feedback torque current signals, and to couple the feedback field current signals to the first error signal generator and the torque current signals of feedback to the second error signal generator, in order to close a motor controller current feedback circuit. In a particular embodiment of the invention, the first integral proportional variable limit controller further includes a first multiplier coupled to receive the field current error signals, to generate a signal representative of a proportional component of the motor field voltage. A first limiter is coupled to the first multiplier to receive the signal representative of a proportional component of the motor field voltage, to limit the signal representative of a proportional component of the motor field voltage to the maximum voltage of the bus, in order to generate a signal representative of a limited proportional component of the motor field voltage. A second multiplier is coupled to receive the field current error signals, to generate a signal representative of the first derivative of the integral component of the field voltage. A limited state integrator is coupled to the second multiplier to receive the signal representative of the first derivative of the integral component of the field voltage, and to integrate the signal representative of the first derivative of the integral component of the field voltage, in order to create a first integrated signal The first integrated signal is limited to a value such that the sum of (a) the first integrated signal and (b) the signal representative of a proportional component of the flow voltage (c) is not greater than the bus voltage. A first summing configuration is coupled to the first limiter and the limited state integrator, to sum the representative signal of a limited proportional component of the motor field voltage with the first integrated signal, in order to generate signals representative of the commanded flow voltage. In an additional avatar of this mode, the second variable-range integral proportional controller includes a torque limit voltage signal generator coupled to the first integral variable-range proportional regulator, to respond to the commanded flow voltage, generating a signal of torque limit of voltage representing the square root of the difference between (a) the square of the commanded flow voltage and (b) the square of the available bus voltage. A third multiplier is coupled to receive the torque current error signals, to generate a signal representative of a proportional component of the motor torque voltage. A second limiter is coupled to the third multiplier to receive the proportional component of the motor torque voltage, to limit the proportional component of the motor torque voltage to the value represented by the torque voltage limit signal, in order to generate a limited proportional component of the motor torque voltage. A fourth multiplier is coupled to receive the torque current error signals, to generate a signal representative of the first derivative of the integral component of the torque voltage. A second limited state integrator is coupled to the fourth multiplier to integrate the signal representative of the first derivative of the integral component of the torque voltage, in order to create a second integrated signal. The second integrated signal is limited so that the sum of the second integrated signal and the limited proportional component of the motor torque voltage is not greater than the torque limit voltage signal. A second sum configuration is provided to sum the limited proportional component of the motor torque voltage and the second integrated signal to generate the commanded torque voltage. A preferred embodiment uses the system to control a traction motor coupled to the drive wheels of a vehicle that is electrically energized, such as a hybrid electric vehicle. A method according to the invention, to control a induction motor driven from a direct voltage busbar, includes the step of generating field current command signals and torque current command signals. Field current error signals are generated by subtracting field current feedback signals from the field current command signals. Torque current current error signals are generated by subtracting torque current feedback signals from the torque current command signals. The field current error signals are multiplied by the first and second constants to produce field signals and second signals. The field voltage signal is limited to a value that represents no more than the available bus voltage of the direct voltage busbar, in order to produce a limited proportional field voltage signal. The second signals are integrated in a limited state manner, so as to generate integrated field voltage signals, with the state of the integrator limited so that the sum of (a) the limited proportional field voltage signals and (b) the Integrated field voltage signals (c) no longer represent the bus voltage. The limited proportional field voltage signals are summed with the integrated field voltage signals to produce flow voltage command signals. Limiting signals are generated that are representatives of the square root of the difference between (a) the square of the available bus voltage and (b) the square of the flow voltage command. Torque error signals are multiplied by the third and fourth constants, in order to produce signals representative of the proportional component of the torque voltage and a fourth signal, respectively. The signals representative of the proportional component of the torque voltage are limited to represent a value no greater than the limiting signals, in order to produce limited proportional torque voltage signals. The fourth signals are integrated in a limited state manner, so as to generate integrated torque voltage signals, so as to produce integrated torque voltage signals; the state of the integrator is limited in such a way that the sum of (a) the limited proportional torque signals and (b) the integrated field voltage signals only represent the limiting signal. The proportional torque voltage signals and the integrated torque volt- age signals are summed to produce torque voltage command signals. The field voltage command signals and the torque voltage command signals are converted into motor windings. Windings of the motor windings are detected to produce signals detected from motor winding currents, and the detected motor winding current signals are converted to the field current feedback signals and the torque current feedback signals from the motor. torsion. Figure 1. is a simplified plane of flow versus speed in an induction motor; Figure 2 is a simplified block diagram and schematic of a portion of a variable proportional minimum integral integral controller of the prior art using a limited state integrator; Figures 3a, 3b, 3c, and 3d are representations of synchronous structures having axes d and q associated with the operation of an induction motor; and Figure 4 is a simplified diagram in the form of blocks and schematic, illustrating a control circuit of an induction motor in accordance with an aspect of the invention. Figure 3a is a diagram showing bus voltage in the synchronous control structure of a field-controlled controller induction motor, which shows the axes Vq and Vd. In Figure 3a, the circle 310 represents the maximum voltage of busbar, and vector 312 represents the magnitude of the alternating voltage applied to the motor. The vector 312 has a component 314 that is along the axis Vd and a component 316 that is parallel to the axis Vq. An engine operated under the condition illustrated in Figure 3a is at the maximum busbar voltage available, which means that the engine is at a speed that is not less than the rated speed, because at speeds below the rated speed, the counter electromotive force of the motor is less than rated busbar voltage, and a full busbar voltage should not be applied; the full bus voltage only it is applied when the counter electromotive force is high. The regulator output can output a voltage command as illustrated as a vector 318 in Figure 3b, which produces components 320 along the axis Vd, and component 319 along the axis Vq. Obviously, the actual bus voltage can not provide the commanded value 319. Thus, when the applied motor voltage is limited to the actual maximum bus voltage, the vector 318 is reduced in magnitude, with the vector reduced in magnitude 318 illustrated in Figure 3c as 324. When thus reducing, the applied motor voltage 324 produces the components 326 and 328 along the axes d and q, respectively, which are proportionally reduced in magnitude relative to their original values 320 and 319. It has been found that, in controllers such as those described in relation to Figure 2, the proportional reduction in the dyq components of the applied motor voltage produces a transient response characterized by motor currents that are greater than desired, and possibly by some instability in certain modes of operation. In accordance with one aspect of the invention, the applied vector voltage, such as 318 of Figure 3b, is rotated and adjusted in magnitude in the synchronous structure of the field-oriented controller when its commanded value tends to exceed the bus voltage. Thus, in Figure 3d, when the applied command voltage would be represented by the vector 318 of Figure 3b, the commanded voltage it is rather rotated and reduced in magnitude, as represented by the vector 338 of Figure 3b, in such a way as to maintain the magnitude of the flow voltage component 320 of Figure 3b. As illustrated in Figure 3d, the rotated position 338 of the original vector greater than the vector bus 318, and its reduced magnitude produce a q axis or torque component, which is much smaller relative to its original commanded value. It has been found that by maintaining the flow magnitude 320 and allowing the torque magnitude to be reduced, such as from 319 to 339, the motor control is stabilized in relation to the situation, represented in the transition of Figure 3b to 3c, in which the magnitude of the commanded vector 318 is reduced simply without maintaining a more or less constant flow command. Figure 4 is a simplified diagram in the form of blocks and schematic of a control system in accordance with the invention. This particular control system controls the traction motor of an electric motor vehicle, which may be a hybrid electric vehicle. In Figure 4, a field-oriented motor control (FMC) 410 receives input signals of torque and motor speed signals and produces signals id- and iq *, which apply to non-inverting input ports. of the error signal generators 414a and 414b, respectively. The error signal generators 414a and 414b subtract feedback motor current signals idFB and ¡QFB, respectively, from their respective signals id- and iq., To produce error signals of torque and flow in signal paths 415a and 415b, respectively. The field flow error signal (d) of the error signal generator 414a of Figure 4 is applied to a block 490a, which is generally similar to block 10 of Figure 2. In Figure 4, the error signal of the field flux of the error signal generator 414a is applied by a junction of the trajectory 415a to a multiplier 416a, which multiplies the field flux error signal by a proportionality constant Kpd. The field flux error signal multiplied from the output port 416a or multiplier 416a is applied by a summing circuit 488a to the input port 420ai of the limiter 420a. The summing circuit 488a adds a direct feed correction signal VdFF generated by means, illustrated as a block 486a, to the multiplied field flow error signal of the multiplier 416a, to correct the cross-coupling of signals between the channels d and q of the system 400. The cross-coupled corrected multiplied field flow error signal applied to the limiter 420a is limited, as described in relation to the limiter 20 of Figure 2. The upper limit applied to the upper limit input port 420aul of the limiter 420a is equal to the maximum available busbar voltage Vd, spon, b | ß, which in the context of a three-phase induction motor is equal to and 'available (2) The signal Vd¡sp ?n¡bie is produced at the output of the source 22a and is applied directly to the upper limit input port 420aul of the limiter 420a, and via an inverter or operator -1 24a to the lower limit input port 420all of limiter 420a. Thus, the maximum and minimum values of the output signal of the limiter 420a correspond to the available bus voltage. The limited proportional component of the field current voltage the limiter 420a is applied via a signal path 421a to a non-inverting input port of an adder circuit 432a. The field flow error signal (d) of the error signal generator 414a of Figure 4 is also applied by joining the path 415a to a multiplier 418a, which multiplies the field flow error signal by a constant integral Kid. Because the action of the feedback loop, as described below, the field flux error signal multiplied from the output port 418a or multiplier 418a has the dimensions of volts / seconds, and represents the first derivative of the integral component of the field voltage command Vd. The command signal of Field voltage commands the processor or power signal inverter 496 to produce an effective field voltage across the motor windings that is sufficient to produce the equivalent desired field current to flow in the motor. As mentioned above, the signals described here represent the values that their names suggest, so that the field voltage command signal Vd represents, either directly or through a proportionality constant, the actual value of the magnetic field of the field winding of the motor, or the value of the corresponding magnetic field as a function of the field of the field winding, measured in a different coordinate system, so that the signal processing can be described in terms of the representative signals or the values representing the signals. More specifically, the control of the field-oriented controller contemplates the analysis and processing of signals in the dyq coordinates corresponding to the torque and field of the motor, but the currents applied to the induction motor are not easily separable in field components and of torque, but instead are measured in coordinates a, b and c. The first derivative of the integral component of the field voltage command, or more suitably the signal representative of the first derivative of the integral component of the field voltage command, is applied from the output port 418a or of the multiplier 418a to the input port 426ai of a limited state integrator 426a of block 490a. A differentiating circuit 484a has its inverting input port coupled to the signal path 421a to receive the limited proportional component of the field voltage current command, and also has a non-inverting input port coupled to the source 22a, to receive the representative signal of the available bus voltage. The differentiating circuit 484a takes the difference between the component Proportionally limited field voltage command and the available bus voltage, to generate the upper limit signal for application to the upper limit input port 426aul of the limited state integrator 426a. Likewise, a differentiating circuit 482a has an inverting input port coupled to the signal path 421a for receiving the limited proportional component of the field voltage command, and also includes a non-inverting input port coupled to the output of the inverter 24a , to take the difference between the limited proportional component of the field voltage command Vd, and applies the difference to the lower limit input port 426all of the limited state integrator 426a. The limited state integrator 426a produces the integral component of the field voltage command, and applies it on a signal path 427a to a second non-inverting input port of the summing circuit 432a. The summing circuit 432a of Figure 4 adds the limited proportional and limited integral components of the field voltage command, and produces a field voltage command signal Vd on a signal path 433a for application to an illustrated coordinate converter block. as 496. As described below, the coordinate converter block 496 receives the field voltage command signals Vd from the path 433a, the busbar voltage from the busbar 497, and also receives the voltage command signals from torque Vq and the TRF signals indicative of field position of the motor 498, to generate the voltage components a, b and c that energize the windings and command the motor. As mentioned above, the error signal generator 414b subtracts feedback motor current signals Í < , FB of its input signals or reference iq-, to produce torque error signals in the signal path 415b. The torque flow error signal (q) of the error signal generator 414b of Figure 4 is applied to a block 490b, which is generally similar to block 10 of Figure 2 and block 490a of Figure 4 In Figure 4, the error signal of the torque flow of the error signal generator 414b is applied by a path 415b to a multiplier 416b, which multiplies the error signal of the torque flow by a constant of proportionality Kpq. The torque flow error signal multiplied from the output port 416bo of the multiplier 416b is applied by an adder circuit 488b to the input port 420bi of the limiter 420b. The summing circuit 488b adds a feedback field current signal VqFF generated by means, illustrated as a block 486b, to the multiplied field flow error signal of the multiplier 416b, to correct the cross coupling of the signals between the channels d and q of the system 400. The error signal of the cross-coupled corrected multiplied torque flow rate is applied to the limiter 420b and is limited, as described above in conjunction with the limiter 420a.

The control block 490b of Figure 4 includes a block 480 coupled to the bus bar 497 to receive the collector voltage Vbarra collector, and also includes an additional input port 480i coupled to the signal path 433a, to receive the signal Vd field voltage limited command. Block 480 establishes a voltage limiting signal of torque Viím¡tß dß torque, which is applied to a busbar limit torque 481. The value of Torque voltage, calculated in block 480, establishes a limit on the magnitudes of the proportional and integral components of the torque voltage command signals Vq controlled by the block limiters 490b, so that the values at that the torque voltage command signals are allowed, are limited to the rest after the field voltage command signals Vd command the field voltage that may be necessary , in a closed loop condition, to achieve the desired field current. In other words, the values selected in block 480, in conjunction with the limiting values selected in block 490a, give preference to field voltage commands Vd, providing the motor with the field current commanded up to the commanded value, and allowing that the torque voltage command Vq command only the bus voltage that remains available. Thus, in accordance with one aspect of the invention, priority or preference is given to the field current over the torque current.

The value of V? Mt ds torque produced by block 480 of Figure 4 is applied to the upper limit input port 420b of limiter 420b, and an inverted value of V | irnite d.sup.t. , by means of a multiplier circuit -1 or inverter illustrated as 24b, to the lower limit input port 420bll of the limiter 420b. The limiter 420b limits the value of the cross coupling corrected multiplied torque flow error signal applied to the input port 420bi of the limiter 420b so that it is between the + V? ¡M¡e of torque applied to limit the entrance port 420bul and the -Vümitß ß torque applied to the lower limit input port 420bll. The limited proportional component of the torque voltage command Vq is generated at the output port 420bo of the limiter 420b, and is applied in a signal path 421b to a non-inverting input port of a summing circuit 432b, to be summed in the same with a limited integral portion or component of the torque voltage command. The torque error signals produced in the signal path 415b by the error signal generator 414b of Figure 4 are applied to an additional multiplier 418b for multiplication by a constant Kiq, and the resulting signal, which has dimensions of volts / seconds, and represents the first derivative of the integral component of the torque voltage command Vq, is applied to an input port 426bi of a limited state integrator 426b. The limited state integrator 426b integrates the signal applied to its 426bi input port, as long as its state does not exceed the limits applied to its upper and lower bound entry ports 426bul and 426bll, respectively. The value of the upper limit is generated by a differentiator circuit 484b, which includes an inverted input input port for receiving the limited proportional component of the torque voltage command of the signal path 421b, and which also includes an input port not coupled inverter to receive the voltage limit signal of torque V | ¡mt of torque through the path 481 of the block 480. The differentiating circuit 484b takes the difference between the voltage limit signal of torque of Torque V? ¡mte of torque and the limited proportional component of torque torque command, to produce the upper limit value for its application to the upper limit input port 426bul of the limited state integrator 426b. Likewise, an additional differentiating circuit 482b has an inverted input input port for receiving the limited proportional component of the torque voltage command of the signal path 421b, and also includes a non-inverting input port coupled to receive the inverted torque voltage limit signal -V | torque of inverter torque 24b. The limited state integrator 426b produces the limited integrated component of the torque voltage command in the signal path 427b for application to the summing circuit 432b. The summing circuit 432b adds the limited proportional component of the torque voltage command with the limited integrated component of the voltage command of torque to produce the torque command voltage Vq in a signal path 433b. In Figure 4, the field voltage command Vd produced by block 490a in signal path 433a and the torque command Vq produced by block 490b in signal path 433b are summed together in a block 496. The processing block 496 receives representative TRF signals from the angular position of the motor flow 498, the torque and field voltage commands, and converts > 10 commands to abe coordinates, to control the portion of the bus voltage 497, which is applied as energization Va, Vb and Vc to the three-phase windings of the induction motor 498. The angular position of the motor rotor 498 is detected and applies on a signal path? ROt to the controller oriented to field 410 for use in it. The current in the motor windings 498 of FIG. 4 can be determined by measuring current in one of the motor windings a, b and c, such as by measuring the current in paths a and c. Current sensors, illustrated as 478a and 478c, are coupled to the paths a and c of the motor 498, and produce signals representative of current ia and ic that are applied to a computational block illustrated as 476. The block 476, which uses TRF information regarding the position of the field of the 498 motor, it produces motor current feedback signals in synchronous field form, namely in the form of idFB and iqFß signals. which are reapplied to the field-oriented controller 410, and to the inverting input ports of the error signal generators 414a and 414b, respectively. This feedback closes a degenerative feedback loop generally designated 402, which tends to cause the motor currents to flow in a manner that provides the performance represented by the field voltage and torque commands. Other embodiments of the invention will be apparent to those skilled in the art. For example, the signal processors described can be analog or digital, although digital ones are preferred. The digital signals can be processed by dedicated computer equipment processors, or preferably by computer programs operating in a general purpose processor. The digital signals can be in parallel or in series, as required by the nature of the subsystem, with the appropriate conversion. Thus, a system (400) according to the invention uses an energized induction motor (498) of a direct voltage busbar (497) having a bus voltage. The system (400) includes a field-oriented controller (410) to generate mutually orthogonal torque (id *, iq *) and flow ("field") current command commands in a synchronous structure (such as the Figures 3a or 3b). A first error signal generator (410) for subtracting the feedback field current signals (idFB in conductor 413a) of the field current command signals (id *) in order to generate field current error signals (in the path 415a). A second error signal generator (414b) is coupled to the field-oriented controller (410) to subtract feedback torque current signals (iqFB in the signal path 413b) from the torque current commands ( Q *) in order to generate torque current error signals (in path 415b). A first integral proportional variable limit regulator (490a) is coupled to the first generator of error signal (414a) and responds to the flow current error signal. The first integral variable-range proportional regulator (490a) generates commanded flow voltage signals (Vd in signal path 433a) including proportional and integral components (in paths 421a and 427a), respectively) and limits each of the proportional and integral components of the commanded flow voltage (V) to a value such that the sum of the proportional and integral components of the commanded flow voltage (Vd) is not greater than the bus voltage collector available (497). A second variable-range integral proportional controller (490b) is coupled to the second error signal generator (414b) and responds to the torque current error signals. The second variable-range integral proportional controller (490b) generates commanded torque voltage signals (Vq on signal path 433b) including the proportional and integral components (in signal paths 421b and 426b, respectively) and limits each of the proportional and integral components of the commanded torque voltage (Vq) to a selected value such that the magnitude of the vector sum (312 of Figure 3a, for example) of the flow voltage commanded (Vd) and the commanded torque voltage (Vq) is not greater than the available bus voltage (310). A feedback configuration (413a, 413b, 476, 478a, 478b,? ROt) is coupled to detect current in the motor windings 498, to generate the feedback field current signals (idFβ) and the torque current signals torsion feedback (iqFB) and for coupling the feedback field current signals (dFß) to the first error signal generator (414a) and the feedback torque current (iqFß) signals to the second feedback generator error signal (414b) to thereby close a motor controller current feedback circuit (402). The feedback configuration (402) also includes portions (TROT) to detect the position of the motor rotor. In a particular embodiment of the invention, the first variable-range integral proportional controller (490a) additionally includes a first multiplier (416a) coupled to receive the field current error signals, to generate a signal representative of a voltage proportional component. of motor field. A first limiter (420a) is coupled to the first multiplier (416a) to receive the signal (at port 420ai) representative of a proportional component of the field voltage of motor, to limit the signal representative of a proportional component of the motor field voltage to the maximum bus voltage, so as to generate (in the signal path 421a) a signal representative of a limited proportional component of the field voltage of motor. A second multiplier (418a) is coupled to receive the field current error signals, to generate (at port 418ao) a signal representative of the first derivative of the integral component of the field voltage. A limited state integrator (426a) is coupled to the second multiplier (418a) to receive the signal representative of the first derivative of the integral component of the field voltage, and to integrate the signal representative of the first derivative of the integral component of the field voltage , in order to create a first integrated signal. The first integrated signal is limited (by limiting the state of the integrator) to a value such that the sum of (a) the first integrated signal and (b) the signal representative of a proportional component of the flow voltage (c) is not greater that the bus voltage (497); the first integrated signal limited in this way is the integral component of the field voltage command (Vd). A first summing configuration (432a) is coupled to the first limiter (420a) and the limited state integrator (426a) to sum the representative signal of a limited proportional component of the field voltage command with the first integrated signal (equivalent to the integral component of field voltage command) to generate (Vd) voltage representative signals of commanded flow. In an additional avatar of this embodiment, the second variable-range integral proportional controller (490b) includes a torque voltage limit signal generator (480) coupled to the first integral variable-range proportional regulator (490a) to respond to the commanded flow voltage (Vd in signal path 433a) when generating a torque voltage limit signal (on path 481) that represents the square root of the difference between (a) the square of the commanded flow voltage and (b) the square of the available bus voltage. A third multiplier (416b) is coupled to receive the torque current error signals (from path 415b) to generate (at its output port 416bo) a signal representative of a proportional component of the torque voltage command of Engine torque (Vq). A second limiter (420b) is coupled to the third multiplier (416b) to receive the proportional component of the motor torque voltage, to limit the proportional component of the motor torque voltage to the value (in the signal path 481) represented by the torque limit voltage signal, in order to generate (at its output port 420bo) a component Limited proportional torque of the motor torque (Vq). A fourth multiplier (418b) is coupled (to the signal path 415b) to receive the torque current error signals, to generate a signal (at the output port 418b) representative of the first derivative of the integral component of the Torque voltage (Vq).

A second limited state integrator (426b) is coupled to the fourth multiplier (418b) to integrate the signal representative of the first derivative of the integral component of the torque voltage, so as to create (in the signal path 427b) a second signal integrated (which is equivalent to the integral component of the torque voltage command Vq). The second integrated signal is limited in such a way that the sum of the second integrated signal and the limited proportional component of the motor torque voltage is not greater than the torque limit voltage signal (in the signal path) 481). A second summing configuration (432b) is provided to sum the limited proportional component of the motor torque voltage and the second integrated signal, so as to generate the commanded torque voltage (Vq). A preferred embodiment uses the system to control a traction motor (498) stored on the drive wheels (499) of a vehicle (403) which is electrically energized, such as an electric hybrid vehicle.

Claims (8)

1. CLAIMS 1.A system using an energized induction motor of a direct voltage busbar having a bus voltage, said system comprises: a field-oriented controller for generating commands of mutually orthogonal torque and flow currents in a synchronous structure; a first error signal generator is coupled to said field-oriented controller, to subtract the feedback field current signals from said flow current command signals, so as to generate field current error signals; a second error signal generator coupled to such a field-oriented controller for subtracting feedback torque current signals from said torque current command commands, so as to generate torque current error signals; a first variable proportional integral proportional controller coupled to said first error signal generator, and responding to said flow current error signal, such a first integral proportional variable limit controller generates commanded flow voltage signals including proportional and integral components , and limits each of the proportional and integral components of the voltage of said commanded flow to a value such that the sum of the proportional and integral components of the mentioned commanded flow voltage is not greater than the available bus voltage; a second variable proportional integral proportional controller coupled to the second error signal generator, and responding to said torque current error signals, said second variable range integral proportional controller generates command torque voltage signals including proportional and integral components, and limits each of the aforementioned proportional and integral components of the controlled torque voltage to a selected value such that the magnitude of the vector sum of the commanded flow voltage and such commanded torque voltage is not greater than the busbar voltage available; coupled feedback means for detecting current in the motor windings, for generating the said feedback field current signals and said feedback torque current signals, and for coupling such feedback field current signals to the first generator of error signal and said feedback current signals to said second error signal generator, in order to close a motor controller current feedback circuit.
2. 2. A system according to claim 1, wherein said first proportional integral regulator of variable limit additionally includes: a first multiplier coupled to receive said field current error signals, to generate a signal representative of a proportional component of the motor field voltage; a first limiter is coupled to said first multiplier to receive said signal representative of a proportional component of the motor field voltage, to limit such signal representative of a proportional component of the motor field voltage to the maximum voltage of said busbar, so as to generate a signal representative of a limited proportional component of the motor field voltage; a second multiplier coupled to receive the said field current error signals, to generate a signal representative of the first derivative of the integral component of the field voltage; a limited state integrator is coupled to said second multiplier to receive such a signal representative of the first derivative of the integral component of said field voltage, and to integrate said signal representative of the first derivative of the integral component of the field voltage, so as to create a first integrated signal, said first integrated signal is limited to a value such that the sum of said integrated signal and said signal representative of a proportional component of the flow voltage is not greater than the bus voltage; a first summing configuration coupled to said first limiter and said limited state integrator, to add the mentioned signal representative of a limited proportional component of said motor field voltage with the first integrated signal, to generate signals representative of such commanded flow voltage.
3. 3. A system according to claim 2, wherein said second proportional proportional variable limit regulator comprises: a torque limit voltage signal generator coupled to said first integral proportional regulator of variable limit, to respond to said commanded flow voltage, to generate a voltage limit signal of torque that represents the square root of the difference between (a) the square of such commanded flow voltage and (b) the square of the available bus voltage; a third multiplier coupled to receive the said torque current error signals, to generate a signal representative of a proportional component of the motor torque voltage; a second limiter coupled to said third multiplier to receive such a proportional component of the motor torque voltage, to limit said proportional component of the motor torque voltage to the value represented by said torque limit voltage signal , in order to generate a limited proportional component of said motor torque voltage; a fourth multiplier coupled to receive the said torque current error signals, to generate a signal representative of the first derivative of the integral component of such torque voltage; a second limited state integrator coupled to said multiplier fourth to integrate said signal representative of the first derivative of the integral component of said torque voltage, in order to create a second integrated signal, such a second integrated signal is limited so that the sum of said second integrated signal and said limited proportional component of said motor torque voltage is not greater than such a torque voltage limit signal; a second summing configuration, for adding said limited proportional component of said motor torque voltage and said second integrated signal, to generate said commanded torque voltage.
4. 4. A system according to claim 1, further comprising: a vehicle body; and vehicle operating mechanism coupled to said body and said engine, to cause said vehicle to move in response to the rotation of said engine.
5. 5. An electric vehicle using an energized induction traction motor of a direct voltage busbar, said vehicle comprises: a field-oriented controller for generating mutually orthogonal torque and flow current commands in a synchronous structure; a first error signal generator coupled to such a field-oriented controller, for subtracting feedback field current signal from such flow current command signals, so as to generate field current error signals; a second error signal generator coupled to such a field-oriented controller for subtracting feedback torque current signals from said torque current commands, so as to generate torque current error signals; a first variable proportional integral proportional controller coupled to said first error signal generator, and responsive to such a flow current error signal, such a first integral proportional variable limit controller generates command flux voltage signals including proportional components and integral, and limits each such proportional and integral component of said commanded flow voltage to a value such that the sum of such proportional and integral components of said commanded flow voltage is not greater than the available bus voltage: one second proportional variable limit integral regulator coupled to such second error signal generator, and responsive to such torque current error signals, said second proportional variable limiter integral controller generates command torque voltage signals including proportional and integral components, and limiting each of said proportional and integral components of such torque voltage commanded at a selected value such that the magnitude of the vector sum of such commanded flow voltage and said commanded torque voltage is not greater than the voltage busbar available; coupled feedback means for detecting current in the windings of said motor, for generating said feedback field current signals and said feedback torque current signals, and for coupling said feedback field current signals to said first generator of error signal and such feedback torque current signals to said second error signal generator, so as to close a motor controller current feedback circuit.
6. 6. A vehicle according to claim 5, wherein said first integral proportional variable limit controller further comprises: a first multiplier coupled to receive such field current error signals, to generate a signal representative of a proportional component of such motor field voltage; a first limiter coupled to said first multiplier to receive said signal representative of a proportional component of such motor field voltage, to limit said signal representative of a proportional component of said motor field voltage to the maximum voltage of said busbar, for thus generating a signal representative of a limited proportional component of such motor field voltage; a second multiplier coupled to receive said field current error signals, to generate a signal representative of the first derivative of the integral component of such a field voltage; a limited state integrator coupled to said second multiplier to receive said signal representative of the first derivative of the integral component of such a field voltage, and to integrate said signal representative of the first derivative of the integral component of such a field voltage, so as to creating a first integrated signal, such a first integrated signal is limited to a value such that the sum of said first integrated signal and such signal representative of a proportional component of said flow voltage is not greater than said bus voltage; a first summing configuration coupled to said first limiter and such a limited state integrator, for summing said signal representative of a limited proportional component of said motor field voltage and said first integrated signal, for generate signals representative of such commanded flow voltage.
7. 7. A system according to claim 6, wherein said a second variable range integral proportional regulator comprises: a torque limit voltage signal generator coupled to said first integral proportional variable limit regulator, to respond to said voltage of commanded flow, to generate a voltage limit signal of torque which represents the square root of the difference between (a) the square of said commanded flow voltage and (b) the square of the available bus voltage; a third multiplier coupled to receive the said torque current error signals, to generate a signal representative of a proportional component of the motor torque voltage; a second limiter coupled to said third multiplier to receive said proportional component of said motor torque voltage, to limit said proportional component of said motor torque voltage to the value represented by said torque voltage limit signal of torque, in order to generate a limited proportional component of said motor torque voltage; a fourth multiplier coupled to receive said torque current error signals, to generate a signal representative of the first derivative of the integral component of the mentioned torque voltage; a second limited state integrator coupled to such multiplier room to integrate said signal representative of the first derivative of the integral component of said torque voltage, in order to create a second integrated signal; said second integrated signal is limited such that the sum of such second integrated signal and said limited proportional component of said motor torque voltage is not greater than such a torque voltage limit signal; a second summing configuration, for adding said limited proportional component of said motor torque voltage and said second integrated signal, to generate such commanded torque voltage. A method for controlling an induction motor driven from a direct voltage busbar, comprising the steps of: generating field current command signals and torque current command signals; generating field current error signals by subtracting field current feedback signals from said field current command signals; generating torque current error signals by subtracting torque current feedback signals from said torque current command signals; multiply said field current error signals by first and second constants in order to produce field signals and second signals, respectively; limiting said field voltage signal to a value that represents no more than the available bus voltage of such a direct voltage bus, in order to produce a limited proportional field voltage signal; integrating said second signals in a limited state manner, so as to generate integrated field voltage signals, said state is limited such that the sum of said limited proportional field voltage signals and such integrated field voltage signals do not represent more than the said bus voltage; adding said limited proportional field voltage signals and said integrated field voltage signals to thereby produce flow voltage command signals; generating limiting signals representative of the square root of the difference between (a) the square of said available bus voltage and (b) the square of said flow voltage command; multiplying said torque error signals by third and fourth constants, in order to produce signals representative of the proportional component of the torque voltage and a fourth signal, respectively; limit said signals representative of the proportional component of such torque voltage to represent a value no greater than said limiting signals, so as to produce limited proportional torque signal voltage signals; integrating such fourth signals in a limited state manner, in order to generate integrated torque voltage signals, said state is limited in such a way that the sum of said limited proportional torque signals and said voltage signals integrated field do not represent more than such a limiting signal; in order to produce integrated torque voltage signals; adding such proportional torque voltage signals and the aforementioned integrated torque voltage signals to produce torque voltage command signals; converting such field voltage command signals and said torque voltage command signals into motor windings currents; detecting such windings of the motor to produce detected signals of motor windings; converting the above-mentioned detected signals of motor windings currents into said field current feedback signals and such torque current feedback signals. SUMMARY A controller (400) for an induction motor variable speed drive (498) includes a field-oriented (410, 476) control, which in a feedback arrangement (402) detects the engine parameters to form the error signals of field and of torque. The field error signals are processed by a first limited state processor Pl (490a), which individually limits the magnitude of the proportional component of the field voltage to no more than the bus voltage. The field error signals are also processed by a limited state integrator (426a) which limits the integral component of the field voltage to the difference between the proportional component and the bus voltage. A first adder (432a) adds the proportional and integral components to generate the field voltage command. The error signals torque are processed by a limited Pl state processor (490b) which individually limits the proportional component of the voltage torque to a value not greater than the bus voltage available after it has preference to the first Pl processor. the integral component voltage command torque is generated by a-limited state second integrator (426b) which limits the integral component of the voltage command torque so that the command Torque voltage that does not exceed the available bus voltage. A second summing circuit (423b) adds the components proportional and integral of the torque voltage command. The field voltage and torque commands are processed to produce the desired motor torque and torque, and a feedback circuit forces the motor current to follow the command values.