EP1020017A1 - Moteur c.c. a excitation separee, avec commande d'augmentation et de baisse de tension - Google Patents

Moteur c.c. a excitation separee, avec commande d'augmentation et de baisse de tension

Info

Publication number
EP1020017A1
EP1020017A1 EP98950806A EP98950806A EP1020017A1 EP 1020017 A1 EP1020017 A1 EP 1020017A1 EP 98950806 A EP98950806 A EP 98950806A EP 98950806 A EP98950806 A EP 98950806A EP 1020017 A1 EP1020017 A1 EP 1020017A1
Authority
EP
European Patent Office
Prior art keywords
armature
signal
current
generate
field current
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98950806A
Other languages
German (de)
English (en)
Inventor
Robert Gordon Lankin
Joseph K. Hammer
John R. Harman
Christopher M. Killian
David B. Stang
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Crown Equipment Corp
Original Assignee
Crown Equipment Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Crown Equipment Corp filed Critical Crown Equipment Corp
Publication of EP1020017A1 publication Critical patent/EP1020017A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P7/00—Arrangements for regulating or controlling the speed or torque of electric DC motors
    • H02P7/06—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current
    • H02P7/18—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power
    • H02P7/24—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices
    • H02P7/28—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices
    • H02P7/285—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling armature supply only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P7/00—Arrangements for regulating or controlling the speed or torque of electric DC motors
    • H02P7/06—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current
    • H02P7/18—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power
    • H02P7/24—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices
    • H02P7/28—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices
    • H02P7/298—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling armature and field supplies
    • H02P7/2985—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling armature and field supplies whereby the speed is regulated by measuring the motor speed and comparing it with a given physical value

Definitions

  • the present invention relates to control of separately excited DC motors and, more particularly, to a control scheme for a separately excited DC motor wherein a field current signal is selectively boosted or de-boosted to expand the power envelope of the DC motor.
  • a motor control system including a microprocessor programmed to modify the field current of a separately excited motor to account for any reduction in battery voltage by increasing the armature current.
  • the microprocessor is also programmed to generate an armature voltage reference signal and a field current setpoint, compare the armature voltage reference signal to a measured armature voltage signal, generate an armature voltage error signal based on the comparison, and generate a field current correction signal as a function of the armature voltage error signal.
  • the field current is de-boosted when battery voltage begins to fall in order to maintain desired motor performance.
  • Field de-boost is a field current modification based on an error signal between an armature current lookup table value and a measured armature current when armature voltage is substantially equal to battery voltage. Improved control over motor torque within the commutation limit of the motor is achieved for battery conditions below 90% state of charge.
  • the field de-boost calculation adjusts the field current lookup table value to increase actual armature current up to the setpoint value.
  • Field de-boost is only active during motoring, armature current positive forward and reverse states.
  • the microprocessor may be programmed to execute a field current control function wherein optimal field current and armature current setpoints are established in accordance with tabulated values selected for providing a required torque and speed.
  • a table of corresponding armature voltage values is also maintained. Flux losses in the motor are detected indirectly by measuring the motor's armature voltage. Specifically, a reduction of back EMF acting on the armature indicates a flux decrease.
  • a voltage sensor sends measured values of armature voltage to an armature voltage comparator for comparison with expected values thereof as read out from the above-mentioned table. The differences are used for adjusting the field current setpoint and thereby adjusting the flux.
  • the controller of this invention compensates for flux losses by using a table of armature voltage values to determine an armature voltage reference point.
  • An armature voltage sensor measures the actual average armature voltage and sends the measured value back to a microprocessor.
  • the microprocessor compares the measured armature voltage with the armature voltage reference point and multiplies the difference by a variable gain factor to obtain a correction term. The correction term then is added to the field current setpoint in order to adjust flux as required.
  • optimal field current and armature current setpoints are established in accordance with tabulated values selected for providing a required torque and speed.
  • a table of corresponding armature voltage values is also maintained. Flux losses in the motor are detected indirectly by measuring the motor's armature voltage. Specifically, a reduction of back EMF acting on the armature indicates a flux decrease.
  • a voltage sensor sends measured values of armature voltage to an armature voltage comparator for comparison with expected values thereof as read out from the above-mentioned table. The differences are used for adjusting the field current setpoint and thereby adjusting the flux.
  • the controller of this invention compensates for flux losses by using a table of armature voltage values to determine an armature voltage reference point.
  • An armature voltage sensor measures the actual average armature voltage and sends the measured value back to a microprocessor.
  • the microprocessor compares the measured armature voltage with the armature voltage reference point and multiplies the difference by a variable gain factor to obtain a correction term. The correction term then is added to the field current setpoint in order to adjust flux as required.
  • the look-up tables of the present invention output field and armature current values that are optimized to minimize component heating by minimizing armature current.
  • the tables are generated based on empirical fit functions to dynamometer data on a limited sampling of a particular motor configuration. Since the tables are constructed based on a defined model, component tolerances, wear, heating, and state of battery charge can contribute to sample-to-sample variances in resultant output horsepower or energy conversion. Further, since the tables are built using a nominal battery voltage at 90% state of charge, any level below this will not only lower armature voltage but will also lower armature current, resulting in a reduction in peak torques and a corresponding premature loss in vehicle acceleration. Peak torque reduction can be lessened by holding armature currents to their desired level.
  • a motor control system comprising an electrically charged battery, an electrical motor, a battery voltage sensor, an armature voltage sensor, an armature current sensor, and a microprocessor.
  • the electrical motor is coupled to the battery and includes an armature assembly responsive to an armature current and a field assembly responsive to a field current.
  • the magnitude of the armature current is a function of a predetermined armature current setpoint signal l a SET .
  • the battery voltage sensor is arranged to generate an operating battery voltage signal V BAT .
  • the microprocessor is programmed to generate an armature current setpoint signal l a SET , a field current setpoint signal
  • the check function defines a
  • the microprocessor is also programmed to calculate a ratio of the measured armature current signal l a to the field current setpoint signal l f SET to
  • the microprocessor is programmed to establish the field current de-boost signal l f DE _
  • the microprocessor may be programmed to compare the operating ratio value l a / If SET ⁇ ° the corresponding armature current to field current ratio value
  • the microprocessor may be programmed to establish the magnitude of the field current de-boost signal l f DE _
  • BOOST according to a selected one of two distinct de-boost equations.
  • the identity of the selected equation depends upon the outcome of the comparison of the operating ratio value l a / l f SET to the corresponding armature current to field current ratio value
  • 1/ SET represents a de-boosted field current setpoint signal
  • l f GAIN represents a preselected gain parameter
  • the microprocessor is further programmed to generate an armature current error signal l a E RROR by comparing the
  • the microprocessor is programmed to select the first equation when the operating ratio value l a / l f SET is greater than the corresponding armature current to
  • the electrical motor is characterized by a set of commutation limits and the microprocessor is preferably programmed to generate the armature-to-field current check function such that the check function simulates the commutation limits as a function of armature current.
  • the armature-to-field current check function is defined by the following equations:
  • V REF represents a reference battery voltage, e.g., 36 volts
  • ( l a /l f ) SLOPE represents the following product
  • parameter G E-BOOST represents an allowable increase in armature to field current ratio per battery volts.
  • the predetermined slope parameter represents a maximum ratio of armature to field current per amp of armature current.
  • the microprocessor may be programmed to generate the armature to field current check function such that the check function is defined by equation (1) when
  • the microprocessor may further be programmed to: generate a full-on indication signal when the measured armature voltage signal V a is substantially equal
  • V ⁇ > VBAT - VBAT_ TOLERANCE V BA ⁇ TOLERANCE is a predetermined voltage tolerance.
  • the microprocessor is programmed to generate the low armature current indication when ⁇ L_SET - _ TOLERANCE , where l a TOLERANCE ' S a predetermined current tolerance.
  • the field assembly may be further responsive to a field current correction signal l f CORRECTION' the motor control system may further comprise a motor speed sensor arranged to generate an actual motor speed signal CO representative of an actual speed of the electrical motor, and the microprocessor may be further programmed to: generate an armature voltage reference signal V a REF , compare the
  • a motor control system comprising an electrically charged battery, an electrical motor, a battery voltage sensor, a motor speed sensor, an armature voltage sensor, an armature current sensor, and a microprocessor.
  • the electrical motor is coupled to the battery and includes an armature assembly responsive to an armature current and a field assembly responsive to a field current.
  • the magnitude of the armature current is a function of a predetermined armature current setpoint signal l a SE7 - and the magnitude of the field current is a function of a predetermined field current setpoint signal l f SET , a field current correction signal l f CORRECTION' ar) d a field
  • the microprocessor may further be programmed to generate the field current correction signal su c that it is inversely proportional to the actual
  • V a RROR is the armature voltage error signal
  • C 1 is a constant
  • G v is a variable gain parameter
  • CO is the actual speed of the motor.
  • the microprocessor may be further programmed to modify the measured armature voltage signal V a by summing the measured armature voltage signal V a and the
  • the motor control system may further comprise a speed command generator arranged to generate a speed command signal S indicative of a desired speed of the electrical motor and the microprocessor may be further programmed to generate the armature voltage reference signal V a REF , the field current setpoint l f SET , and the
  • the microprocessor may additionally be programmed to generate the armature voltage reference signal V a REF , the field
  • the look-up table may be a dual-input look-up table, wherein a first input of the look-up table comprises a torque setpoint signal T SET , and wherein a second input of the look-up table comprises the actual motor speed signal CO .
  • the microprocessor may be programmed to generate the torque setpoint signal
  • T SET as a function of the actual motor speed signal CO and the speed command signal ⁇ .
  • a motor control system comprising an electrical motor, a motor speed sensor, a speed command generator, an armature voltage sensor, and a microprocessor.
  • the electrical motor includes an armature assembly and a field assembly.
  • the armature assembly is responsive to an armature current, the magnitude of which is a function of a predetermined armature current setpoint.
  • the field assembly is responsive to a field current, the magnitude of which is a function of a predetermined field current setpoint and a field current correction signal.
  • the motor speed sensor is arranged to generate an actual motor speed signal representative of an actual speed of the electrical motor.
  • the speed command generator is arranged to generate a speed command signal indicative of a desired speed of the electrical motor.
  • the armature voltage sensor is arranged to generate a measured armature voltage signal from an electrical potential of the armature assembly.
  • the microprocessor is programmed to: (i) generate an armature voltage reference signal, the field current setpoint, and the armature current setpoint, wherein the armature voltage reference signal, the field current setpoint, and the armature current setpoint as a function of the speed command signal and the actual motor speed signal; (ii) compare the armature voltage reference signal to the measured armature voltage signal and generate an armature voltage error signal based on the comparison; and, (iii) generate the field current correction signal as a function of the armature voltage error signal.
  • the microprocessor may further be programmed to generate the field current correction signal such that it is inversely proportional to the actual motor speed signal.
  • the microprocessor may also be programmed to generate the field current correction signal as a function of the armature voltage error signal and the actual motor speed signal. Further, the microprocessor may be programmed to generate the field current correction signal in response to the armature voltage error signal and the actual motor speed signal or to generate the field current correction signal If _ correction according to the following equation:
  • V a RROR is the armature voltage error signal
  • C 1 is a constant
  • G v is a
  • the armature voltage sensor is preferably arranged to measure armature voltage at the low voltage node.
  • the microprocessor may be programmed to modify the measured armature voltage signal by summing the measured armature voltage signal and the battery voltage signal prior to comparing the measured armature voltage signal to the armature voltage reference signal.
  • the microprocessor may be programmed to generate the armature voltage reference signal, the field current setpoint, and the armature current setpoint from a look-up table.
  • the look-up table is a dual-input look-up table, wherein a first input of the look-up table comprises a torque setpoint signal, and wherein a second input of the look-up table comprises the actual motor speed signal.
  • the microprocessor may be programmed to generate the torque setpoint signal as a function of the speed command signal and the actual motor speed signal.
  • the microprocessor may be programmed to generate the armature voltage reference signal, the field current setpoint, and the armature current setpoint from a look-up table having at least one input value derived from the speed command signal and the actual motor speed signal.
  • a motor control circuit comprising a motor speed sensor, a speed command generator, an armature voltage sensor, and a microprocessor programmed to: (i) generate an armature voltage reference signal, a field current setpoint, and an armature current setpoint, wherein the armature voltage reference signal, the field current setpoint, and the armature current setpoint are generated as a function of the speed command signal and the actual motor speed signal; (ii) compare the armature voltage reference signal to the measured armature voltage signal and generate an armature voltage error signal based on the comparison; and, (iii) generate a field current correction signal as a function of the armature voltage error signal.
  • a motor control system comprising an electrical motor, a motor speed sensor, an armature voltage sensor, and a microprocessor programmed to: (i) generate an armature voltage reference signal and the field current setpoint; (ii) compare the armature voltage reference signal to the measured armature voltage signal and generate an armature voltage error signal based on the comparison; and, (iii) generate the field current correction signal as a function of the armature voltage error signal.
  • a motor control circuit comprising a motor speed sensor, an armature voltage sensor, and a microprocessor programmed to: (i) generate an armature voltage reference signal and a field current setpoint; (ii) compare the armature voltage reference signal to the measured armature voltage signal and generate an armature voltage error signal based on the comparison; and (iii) generate a field current correction signal as a function of the armature voltage error signal.
  • a motor control system comprising an electrical motor, a motor speed sensor, a speed command generator, an armature voltage sensor, and a microprocessor.
  • the electrical motor is driven by a battery voltage characterized by a battery voltage signal, and includes an armature assembly including high and low voltage nodes and a field assembly.
  • the armature assembly is responsive to an armature current, wherein a magnitude of the armature current is a function of a predetermined armature current setpoint.
  • the field assembly is responsive to a field current, wherein a magnitude of the field current is a function of a predetermined field current setpoint and a field current correction signal.
  • the motor speed sensor is arranged to generate an actual motor speed signal representative of an actual speed of the electrical motor.
  • the speed command generator is arranged to generate a speed command signal indicative of a desired speed of the electrical motor.
  • the armature voltage sensor is arranged to generate a measured armature voltage signal from an electrical potential of the armature assembly at the low voltage node.
  • the microprocessor is programmed to: (i) generate an armature voltage reference signal, the field current setpoint, and the armature current setpoint from a dual-input look-up table, wherein a first input of the look-up table comprises a torque setpoint signal, wherein a second input of the look-up table comprises the actual motor speed signal, and wherein the microprocessor is programmed to generate the torque setpoint signal as a function of the speed command signal and the actual motor speed signal; (ii) compare the armature voltage reference signal to the measured armature voltage signal and generate an armature voltage error signal based on the comparison; (ii) modify the measured armature voltage signal by summing the measured armature voltage signal and the battery voltage signal prior to comparing the measured armature voltage signal to the armature voltage reference signal; and, (iii) generate the field current correction signal If correction according to the following equation:
  • Other objects of the present invention will be apparent in light of the description of the invention embodied herein.
  • Fig. 1 is a schematic block diagram illustrating a motor control system of the present invention
  • Figs. 2 and 3 are complementary portions of a detailed schematic block diagram illustrating a motor control system of the present invention
  • Fig. 4 illustrates the manner in which Figs. 2 and 3 are combined to form a complete detailed schematic block diagram of the motor control system of the present invention
  • Fig. 5 is a flow chart illustrating the process by which voltage and current values are determined and stored in look-up tables according to the present invention
  • Fig. 6 is a graph illustrating a pair of commutation limit plots for a separately excited DC motor
  • Figs. 7A-C are flow chart illustrating alternate field current modification schemes of the present invention.
  • Fig. 8 is a flow chart illustrating a field current compensation scheme of the present invention.
  • Fig. 9 is a flow chart illustrating a field current de-boost scheme of the present invention.
  • Fig. 10 is a graph illustrating the manner in which an armature-to-field current check function is generated according to the present invention.
  • Fig. 11 is a graph illustrating the behavior of motor speed (left y-axis) and torque (right y-axis) as a function of acceleration time, without field current de-boost
  • Fig. 12 is a graph illustrating the behavior of armature current as a function of acceleration time, without field current de-boost
  • Fig. 13 is a graph illustrating the behavior of field current as a function of acceleration time, without field current de-boost;
  • Fig. 14 is a graph illustrating the behavior of armature voltage as a function of acceleration time, without field current de-boost
  • Fig. 15 is a graph illustrating the behavior of motor speed (left y-axis) and torque (right y-axis) as a function of acceleration time, with field current de-boost;
  • Fig. 16 is a graph illustrating the behavior of armature current as a function of acceleration time, with field current de-boost
  • Fig. 17 is a graph illustrating the behavior of field current as a function of acceleration time, with field current de-boost
  • Fig. 18 is a graph illustrating the behavior of armature voltage as a function of acceleration time, with field current de-boost.
  • the motor control system 100 comprises an electrical motor 10 including an armature assembly 12 and a field assembly 14, a speed command generator 16, an armature voltage sensor (see line 45), a microprocessor 15, and a motor control circuit 20.
  • Shown within the microprocessor 15 are several blocks that represent functions performed by the microprocessor 15 and the associated hardware.
  • the blocks or routines of particular interest include a speed comparator function 50, a set of two-way look up tables 60, an armature voltage error function 70, an armature current error function 73, and a field current modification function 75.
  • the speed comparator function 50 compares a speed command signal on a line 35 to the actual motor speed signal on the line 30 and, in response thereto, provides a torque command signal on a line 55 to the look up tables 60.
  • Figs. 2 and 3 which figures represent respective portions of the entire motor control system 100 and which figures are interconnected to one another as shown in Fig. 4, the speed command signal S on the line 35 and the actual speed
  • microprocessor 15 More specifically, the signals S and CO are inputs to a comparator
  • the gain of Kp of the amplifier function 52 and the gain Ki of the amplifier function or amplifier 53 are conditionally proportional to the motor speed signal on the line 30. At low motor speed, the gain is higher than at higher speeds. This provides stability and the necessary torque for hill holding.
  • the amplifier 52 provides the initial response to a new speed command.
  • the response from the integrator amplifier 53 builds up slowly and predominates as the speed error is driven to zero.
  • the steady state output from the integrator amplifier 53 produces torque setpoint values appropriate for handling a steady state load with no error signal from the speed comparator 51.
  • table 62 contains a matrix of expected armature voltage values V a
  • table 64 contains a matrix of field current values l f
  • table 66 contains a matrix of armature current values l a . Field current and armature current setpoints are produced by the look-up tables 64 and 66, based upon the actual speed signal CO and the torque command or torque setpoint signal on the line
  • the field current setpoint is modified by the field current modification function 75, as will be explained in detail below.
  • the field current modification function 75 includes two distinct components: field current compensation (also identifiable as field current boost) and field current de-boost.
  • field current compensation also identifiable as field current boost
  • field current de-boost The field current compensation component is described in detail herein with reference to Figs. 1-3 and 8.
  • the field current de-boost component is described in detail herein with reference to Figs. 1-3 and 9-18.
  • Fig 7A The first scheme for achieving field current compensation and field current de- boost is illustrated in Fig 7A, wherein the field modification routine 200 first determines whether field compensation is needed, see step 202. If field compensation is needed, it is executed, see step 204, if not, the routine 200 determines whether field de-boost is needed, see step 206. If field de-boost is needed, it is executed, see step 208, if not, the routine returns to step 202.
  • the field modification routine 200' of Fig. 7B is slightly different that the routine 200'. Specifically, the field modification routine 200' first determines whether field compensation is needed, see step 210.
  • step 212 If field compensation is needed, it is executed, see step 212, and the routine returns to step 210 without even attempting to determine if de-boost is needed. If, and only if, field compensation is not needed, does the routine 200' attempt to determine whether field de-boost is needed, see step 214. If field de-boost is needed, it is executed, see step 216, if not, the routine returns directly to step 210.
  • the field compensation routine 200" of Fig. 7C is similar to the one illustrated in Fig. 7B. Specifically, the field modification routine 200" first determines whether field de-boost is needed, see step 218.
  • field de-boost is needed, it is executed, see step 220, and the routine returns to step 218 without even attempting to determine if field compensation is needed. If, and only if, field de-boost is not needed, does the routine 200" attempt to determine whether field compensation is needed, see step 222. If field compensation is needed, it is executed, see step 224. If not, the routine returns directly to step 218.
  • field compensation routine 200' of Fig. 7B field compensation may be identified as the primary modification scheme
  • field de-boost may be identified as the primary modification scheme. Selection of an appropriate modification scheme 200, 200', 200" is dependent upon the specific programming preferences of those practicing the present invention.
  • the alternative routines are merely presented herein to provide a clear description of the present invention. The specific steps involved with executing field current compensation and field current de-boost are described in detail below with reference to Figs. 8-10. Field Current Compensation.
  • a voltage signal on the line 45 from the armature assembly 12, from which flux level is derived, is fed back to the armature voltage error function 70 of the microprocessor 15.
  • the field current modification function 75 adjusts the field current setpoint in accordance with the signal output from the armature voltage error function 70. Specifically, if the armature voltage on the line 45 is not what is expected, based on the torque command signal on the line 55 and the actual speed of the motor represented on the line 30, then the field current signal on a line 42 is adjusted accordingly. The reason armature voltage will not be as expected is due primarily to hysteresis in the flux characteristics in the motor field poles, and also to motor-to-motor manufacturing tolerances.
  • the armature voltage values V a in table 62 are calculated based on the expected flux.
  • the expected flux is determined as a function of the nominal flux characteristics of the particular motor.
  • the actual flux of the motor will be somewhat different from the expected flux, due primarily to hysteresis.
  • the motor control scheme of the present invention accounts for this difference in flux by adjusting the field current.
  • the armature voltage error function 70 includes a comparator function 72 that receives a signal representing battery voltage on a line 71 and a signal representing the voltage V a1 from the low voltage side of the armature bridge on the line 45.
  • Both lines 45 and 71 include analog to digital, or A-D, converter circuits, 92 and 93, see
  • K K x B x ⁇
  • B the magnetic flux in the air gap of the motor (the gap between the poles of the field assembly 14 and the core of the armature assembly 12)
  • C ⁇ the rotational speed of the armature assembly 12.
  • V a RROR ' S the armature voltage error signal A (see Fig. 2)
  • C ⁇ is a constant
  • Gv is a variable gain parameter
  • ⁇ is the actual speed of the motor
  • the magnitude of the field current correction signal is inversely proportional to the actual motor speed signal C ⁇ .
  • the constant C ⁇ includes the motor constant K , unit
  • Nc is the number of conductors in the armature assembly 12
  • NP is the number of poles in the armature assembly 12
  • NA is the number of parallel armature current paths in the armature assembly 12.
  • Gv the variable gain parameter
  • a threshold motor speed C ⁇ B00ST below which the armature voltage error function will be inactivated.
  • a maximum armature voltage setpoint threshold slightly below the actual value of the battery voltage, e.g., about 0.03 volts below the actual value of the battery voltage.
  • the field current will be adjusted only where: (i) the actual motor speed is greater than a minimum speed threshold corresponding to the adjusted field current setpoint; and (ii) the actual armature voltage is less than the armature voltage setpoint.
  • the degree to which the field current may be increased by the armature voltage error function 70 there are no limitations placed on the degree to which the field current may be increased by the armature voltage error function 70, with the exception, of course, that the field current and the armature voltage setpoint cannot exceed the physical limitations of the battery power source.
  • the maximum field current cannot be greater than the battery voltage divided by the field resistance and the armature voltage setpoint cannot be greater than the battery voltage.
  • the routine 300 includes three distinct queries. According to a first query, the routine 300 establishes a maximum value for the armature voltage setpoint when the armature voltage setpoint is close to, or greater than, the actual value of the battery voltage, see steps 302, 304. According to a second query, the routine 300 determines whether the actual motor speed C ⁇ is greater than the predetermined threshold motor speed
  • a final query determines whether the actual armature voltage is less than the armature voltage setpoint, see step 308. If the actual armature voltage is less than the armature voltage setpoint, the field current is corrected according to the above-described algorithm, see step 312. If the actual armature voltage not less than the armature voltage setpoint, a command to disable field current compensation is generated, see step 310.
  • the armature assembly 12 of the motor 10 is responsive to an armature current, the magnitude of which is a function of a predetermined armature current setpoint signal l a S£7 - (see Fig. 2, line 40).
  • the field assembly 14 is responsive to a field current, the magnitude of which is a function of a predetermined field current setpoint signal l f SET (see line 41) and a field current de-boost signal
  • the microprocessor 15 is programmed to generate the
  • the microprocessor 15 is programmed to generate the field current de-boost signal l f DE-BOOST ⁇ ° accomplish suitable modification of the field current according to the present invention.
  • the field current de-boost routine 400 illustrated in Fig. 9 as will be described in greater detail in the following paragraphs, the field current de- boost signal l f DE-BOOST ' S generated after performing a set of predetermined threshold queries, see steps 402, 404, and 406.
  • an armature-to-field current check function is generated that defines a set of armature current to field current ratio values ( l a lf )cHECK as a function of armature current, see steps 408, 410, and 412.
  • An operating ratio value l a / l f SE ⁇ is established and compared to a
  • the first threshold query is designed to generate a "no de-boost" condition unless the motor 10 is being operated in a "full-on” condition, see steps 402 and 406. Specifically, a full-on indication signal is generated when the measured armature voltage signal V a is substantially equal to the operating battery voltage signal V BAT ,
  • the armature voltage signal V a may be measured directly from the armature or measured indirectly through measurements of the output V a ' of the comparator function 72 on line 69 and the battery voltage signal ⁇ / ⁇ 7 - on
  • the field current de-boost signal l f DE-BOOST is not generated under the "no de-boost" condition.
  • the second threshold query is designed to generate a "no de-boost” condition if the armature current is not below a predetermined armature current value, see steps 404 and 406. Specifically, an armature current error signal l a E RROR is
  • a low armature current indication signal is
  • the generation of the low armature current indication signal is conditioned upon whether the armature current error signal l a RROR exceeds a predetermined current tolerance value
  • the armature-to-field current check function is generated so as to simulate the commutation limits of the electrical motor 10 being controlled. Specifically, referring to Figs. 6 and 10, the commutation limits of the electrical motor 10 are illustrated. In Fig. 6, the commutation limits of the field and armature currents are plotted for a motor operating at 24 volts and a motor operating at 36 volts. As the graph illustrates, the number of specific armature and field current combinations for operation below the commutation limits of the motor increases as the operating voltage decreases. In Fig.
  • the commutation limit ratio ( l a / l f ) is plotted as a function of armature current, for each operating voltage, to help illustrate the manner in which the check function is determined. Specifically, the check function is generated so as to simulate the commutation limits ratio as a function of armature current for the electrical motor 10 operating at 36 volts. As is described in detail herein appropriately selected gain parameters are utilized to correct the function for operating voltages other than 36 volts. Referring specifically to Fig. 10, a check function according to the present invention is illustrated as the combination of two distinct sub-functions or lines C 1 and
  • the lines C ⁇ C 2 are defined so as to represent a close fit approximation of the actual commutation limit ratio plotted as a function of armature current.
  • the armature-to-field current check function is defined by the following equations:
  • JMAX represents the maximum armature current to field current ratio
  • V REF represents a reference battery voltage of the commutation limit plot to which the sub-functions or lines are fit, 36 volts in the illustrated example.
  • Slope represents the following product
  • the predetermined gain parameter G DE . B00ST represents the allowable increase in armature to field current ratio per battery volts.
  • the predetermined slope parameter Tn DE _ B00ST corresponds to a maximum ratio of armature to field current per amp of armature current.
  • the check function is defined by equation (1) when
  • the microprocessor 15 is programmed to establish the magnitude of the field current de-boost signal l f DE-BOOST according to a selected one of two distinct de-boost equations, see steps 416 and 418. The identity of the selected equation depends upon the outcome of the comparison of the operating ratio value l a / l f SET ⁇ ° the corresponding armature current to field current
  • l f GAIN represents a preselected gain parameter that is selected to optimize
  • l ⁇ GAIN will range from about 0.1 to about 1.0.
  • the microprocessor is programmed to generate the armature current error signal l a RROR by comparing the armature current setpoint signal l a SET and
  • the microprocessor 15 is programmed to select equation (3) when the operating ratio value l a / l f SET is greater than the corresponding armature current to
  • Figs. 11-18 illustrate the effectiveness of the above-described field de-boost control scheme.
  • Figs. 11-14 illustrate speed, torque, armature current, field current, armature voltage, and battery voltage values, over time, as a motor is subject to acceleration without field current de-boost control according to the present invention.
  • actual speed 500 is significantly lower that the set speed 505 and that actual torque 510 is significantly lower than the set torque 515.
  • actual armature current 520 is significantly lower than the armature current set point 525.
  • the field current set point 535 and actual field current 530 are illustrated in Fig. 13.
  • the battery voltage 545, armature voltage 540, and armature voltage setpoint 550 are illustrated in Fig. 14. ln contrast, the values illustrated in Figs. 15-18 correspond to acceleration executed under the field current de-boost control according to the present invention. Referring initially to Fig. 15, with de-boost control, the actual speed 600 comes much closer to the set speed 605 and reaches a higher maximum value than the actual speed 500 in Fig. 11. Similarly, the actual torque 610 is very close to the set torque 615.
  • Fig. 16 illustrates the close correspondence of the actual armature current 620 and the armature current setpoint 625, particularly when compared with Fig. 12. Fig.
  • FIG. 17 illustrates the fact that the actual field current 630 is less than the look-up table field current setpoint 635.
  • Fig. 18 illustrates the fact that battery voltage 645, the actual armature voltage 640, and the armature voltage setpoint 650 each closely correspond to each other.
  • Fig. 5 represents a routine 110 for minimizing armature current.
  • the first step see block 111 , is to specify model parameter files for the desired motor configuration.
  • the second step see block 112, is to specify battery power constraints, minimum and maximum speed, minimum and maximum torque and look-up table size.
  • the next step, see block 113 is to specify controller hardware current limits and commutation limits.
  • limits on field current range based on power envelope and motor parameters are determined.
  • i m ⁇ n , j m ⁇ n to i max , j max are determined and represent a range of speed and torque setpoints.
  • the field excitation current which results in minimum armature current within a given range is determined.
  • the tables are generated based on empirical fit functions to dynamometer data on a limited sampling of a particular motor configuration. Since the tables are constructed based on a defined model, component tolerances, wear, heating, and state of battery charge can contribute to sample-to-sampie variances in resultant output horsepower or energy conversion.
  • Commutation voltage is calculated in block 118 and this data is put into matrices, see block 119. The process is then repeated, see block 120 for each element (i, j) in the tables. Finally, the tables are compiled, see block 130, and stored. Thus, the following items are calculated and stored: armature current l arm (i,j); field current l fld (i,j); armature voltage V a (i,j); calculated torque (i,j); motor efficiency (i,j); and, commutation voltage(ij).
  • Table 1 is an example of a look-up table giving the desired armature current l a for various values of torque T setpoints (left vertical column) and actual speed (top row).
  • Table 2 is an example of a look-up table for desired field current / at specified torques and speeds.
  • Table 3 is an example of a look-up table that provides expected armature voltages V a at those specified torques and speeds.
  • Table 4 represents expected torque.
  • the torque value T in newton-meters (Nm) is provided by the speed comparator function 50 of the microprocessor 15 and the actual speed value is provided by the encoder 25. Speed is given in radians/second.
  • the torque values in each table are in 5 newton-meter increments and the speed ranges from 0 to 400 radians/second.
  • the data in these specific tables are unique to a given motor configuration or design since they are generated with reference to such factors that include but are not limited to the size, torque, and speed of the motor and internal motor losses. Interpolation may be used to determine values of l f , l a and V g for intermediate speed and torque values. It is important to note that, although the following look-up tables are presented in substantial detail, the information embodied therein could be gleaned, through interpolation and routine experimentation, from a significantly abbreviated reproduction of the tables. Table 1 - 1 ARM
  • the above tables may be expanded to include more values corresponding to more frequent torque and speed intervals.
  • closed loop control circuits for maintaining both the armature and the field current at desired values, namely, armature current control circuit 80 and field current control circuit 82, see Figs. 1 and 3.
  • the outputs from these circuits are connected to the armature assembly 12 and the field assembly 14 of the motor 10.
  • These circuits receive feedback inputs from current sensors associated with the motor control circuits 80, 82.
  • the armature current and adjusted field current setpoint values on the lines 40 and 42 are applied to closed-loop control circuits 80 and 82 after being converted to analog form by digital-to-analog converters 83 and 84, see Figs. 2 and 3.
  • the two control circuits 80 and 82 include current delivery circuits including a bridge logic arrangement which apply switching signals to an arrangement of MOSFET devices that separately regulate the flow of current from a battery 90 to the field and armature coils F and A, respectively.
  • the current delivery circuits of the control circuits 80 and 82 include current sensors 96 and 97 which generate feedback signals, l a feedback 93 and l f feedback 94, respectively, proportional to the respective measured currents. These feedback signals are applied to a pair of comparators 85 and 86 for comparison with corresponding setpoint values. The comparators 85 and 86 then generate an armature current error signal and a field current error signal, respectively.
  • a pair of amplifiers 87, 88 multiply the field current error signal and the armature current error signal by gain factors K 2 and K 3 , respectively.
  • These circuits cause a pair of pulse width modulated (PWM) drives to supply battery current to the motor coils in pulses of constant amplitude and frequency.
  • the amplitude of the pulses varies as a function of the state of charge of the associated battery.
  • the duty cycles of the pulses correspond to the respective setpoint values. This effectively sets the average field current and the average armature current so as to develop the desired torque in the armature.
  • the armature voltage as represented by the output of the comparator 72, will reflect flux losses. If there has been an unexpected loss of field flux, the torque generated by the motor will decrease.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Direct Current Motors (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)

Abstract

L'invention concerne un système de commande de moteur comprenant une batterie chargée électriquement, un moteur électrique, un détecteur de tension de batterie, un détecteur de vitesse du moteur, un détecteur de tension d'induit, un détecteur de courant d'induit et un microprocesseur. L'intensité du courant d'induit appliqué au moteur est une fonction d'un signal de point de consigne correspondant à un courant d'induit prédéterminé et l'intensité du courant d'excitation appliqué au moteur est une fonction d'un signal de point de consigne correspondant à un courant d'excitation prédéterminé, d'un signal de correction du courant d'excitation et d'un signal de baisse de tension du courant d'excitation. Le microprocesseur programmé de manière à produire un signal de point de consigne de courant d'induit, un signal de point de consigne de courant d'excitation et un signal de référence de tension d'induit. Le microprocesseur est en outre programmé pour (i) comparer le signal de référence de tension d'induit au signal de tension d'induit mesurée et produire un signal d'erreur de tension d'induit sur la base de cette comparaison; (ii) produire un signal de correction de courant d'induit qui est une fonction du signal d'erreur de tension d'induit; (iii) générer une fonction de vérification du courant entre l'induit et le courant d'excitation, cette fonction de vérification définissant un ensemble de valeurs pour le rapport courant d'induit-courant d'excitation en tant que fonction du courant d'induit; (iv) calculer un rapport entre le signal de courant d'induit mesuré et le signal de point de consigne du courant d'excitation pour établir une valeur de rapport de fonctionnement, (v) comparer la valeur de rapport de fonctionnement à une valeur correspondante du rapport courant d'induit-courant d'excitation définie par la fonction de vérification du rapport courant d'induit-courant d'excitation, et (vi) déterminer un signal de baisse de tension du courant d'excitation, l'amplitude du signal de baisse de tension étant une fonction du signal de courant d'induit mesuré et de la comparaison de la valeur du rapport de fonctionnement avec la valeur de rapport correspondante.
EP98950806A 1997-09-30 1998-09-29 Moteur c.c. a excitation separee, avec commande d'augmentation et de baisse de tension Withdrawn EP1020017A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US6043097P 1997-09-30 1997-09-30
US6046097P 1997-09-30 1997-09-30
US60430P 1997-09-30
US60460P 1997-09-30
PCT/US1998/020546 WO1999017436A1 (fr) 1997-09-30 1998-09-29 Moteur c.c. a excitation separee, avec commande d'augmentation et de baisse de tension

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EP1020017A1 true EP1020017A1 (fr) 2000-07-19

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KR (1) KR20010024334A (fr)
AU (1) AU9675998A (fr)
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JP4820243B2 (ja) 2006-08-31 2011-11-24 日立オートモティブシステムズ株式会社 自動車の制御装置

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US4423362A (en) * 1982-05-19 1983-12-27 General Electric Company Electric vehicle current regulating system
DE3541276A1 (de) * 1985-11-22 1987-05-27 Heidelberger Druckmasch Ag Steuervorrichtung fuer einen fremderregten gleichstromantriebsmotor und verfahren zum steuern eines gleichstromantriebsmotors einer druckmaschine oder dergleichen
US5039924A (en) * 1990-05-07 1991-08-13 Raymond Corporation Traction motor optimizing system for forklift vehicles

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See references of WO9917436A1 *

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KR20010024334A (ko) 2001-03-26
WO1999017436A1 (fr) 1999-04-08
AU9675998A (en) 1999-04-23
CA2304294A1 (fr) 1999-04-08
CA2304294C (fr) 2010-01-19

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