JPS5932307A - Controller for motor of electric vehicle - Google Patents

Abstract

PURPOSE:To correct load efficiently by forcibly setting a field current value to be flowed through a corresponding motor at an upper limit value or a lower limit value when field current values to be flowed through each motor are upper limit values or more, or lower limit values or less. CONSTITUTION:The mean value IAV and deviation ID are arithmetically operated from the armature currents IA1, IA2 of armatures A1, A2, and a field current indicating value IF is read from a data table 19 from an accelerator opening ACC and the mean value IAV. IF is used as it is when the armature currents IA1, IA2 are approximately equal, and K(IA1-IA2)/2 (K: a constant) is added to IF or subtracted from IF to field current indicating values IF1, IF2 when the armature currents are not equal. When the field current indicating values are a max.-strengthening field current value IFmax or more or a min.-weakening field current value IFmin or less, the field current indicating values are set forcibly at IFmax or IFmin while the other field current indicating value is varied only by the set varied section.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor control device for an electric vehicle, and more particularly to a motor control system for an electric vehicle that equalizes load sharing among the motors when the motors are operated in parallel.

When a plurality of electric motors are operated in parallel, each electric motor always has variations in characteristics, so that variations in load sharing occur between the motors. When such variations in load sharing occur, a large current flows through a particular motor, generating heat and causing burnout. In particular, in the case of electric vehicles, the load fluctuations are more severe than in electric vehicles, so the above-mentioned problems are more likely to occur. Furthermore, in the case of trains, the rating of the electric motor is selected to be large with a margin in mind, but on the other hand, the motor of an electric vehicle has less margin, so it is more likely to cause the above-mentioned problems.

In order to solve the above-mentioned drawbacks, the following @ placements have been used in the past. In other words, when operating multiple motors in parallel, the value of the current flowing through the armature of each motor is detected, and based on the detection result, the value of the field current flowing through the field winding of each motor is increased or decreased to control the load. The division of labor was evenly distributed. However, such conventional motor control devices have a drawback in that it is difficult to equalize the loads when the variations in the loads of the respective motors are very large. because,
This is because, in general, in a motor having a shunt field, the load on the motor can be effectively corrected by increasing or decreasing the field current only within a certain range. That is,
This is because if the field current exceeds an upper limit value or a lower limit value determined by the rating of the motor, etc., the amount of correction for the motor load reaches a ceiling and correction cannot be performed as instructed.

Therefore, the main object of the present invention is to provide an electric motor material tI for an electric vehicle that can reliably equalize the load sharing even when the load variation between each electric motor is very large.
II device.

In summary, when at least two electric motors are operated in parallel, one of the field current values to be passed through the field windings of each electric motor is determined based on the armature current value of each electric motor. "Forcibly sets the field current of the corresponding motor when it exceeds a predetermined upper limit or lower limit.": Sets the field current of the corresponding motor to the limit or lower limit, and The field Ii current value determined for the other motor gradually decreases or increases in accordance with the setting change.

The above objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 1 is a schematic block diagram showing one embodiment of the present invention. In the figure, an armature A1 of an electric motor (hereinafter referred to as a motor) Ml is connected in series with a DC power supply 1, and a shunt resistor S
H1 is connected. This armature A1 and shunt resistance S
A series circuit including armature A2 of motor M2 and shunt resistor SH2 is connected in parallel to the series circuit with H1. The Nvs current detection circuit 11 detects the armature current IA1 flowing through the armature A1 based on the voltage across the shunt resistor SH1. Similarly, it armature current detection circuit 1
2 is the armature A2 due to the voltage across the shunt resistor SH2.
Detects the armature current IA2 flowing through the armature current IA2. Each output of the armature current detection circuits 11 and 12 is given to an A/D converter 13 and converted into, for example, a 16-pit digital signal. The output of the A/D converter 13 is given to the CPL 115 via the I10 interface 14. The accelerator opening detection circuit 16 is a circuit for detecting the amount of depression of an accelerator pedal (not shown) of an electric vehicle, and its output is given to an A/D converter 17 and converted into, for example, a 4-bit digital signal. converted. The output of the A/D converter 17 is given to the CPU 15 via the I10 interface 14.

5- Connected to the CPU 15 are a ROM 18 in which an operating program as shown in FIG. 4 is stored, for example, and a ROM 19 in which a data table as shown in FIG. 2 is stored, for example. Further, a RAM 20 having a storage area as shown in FIG. 3, for example, is connected to the CPU 15. C.P.
The field current instruction data output from U15 is sent via the I10 port 14 to D/A! l' converter 23.

The D/A converter 1!23 converts the field current instruction data given from the CPU 15 into an analog signal and supplies it to the corresponding field current control circuit 21 or 22. The field current control circuit 21 controls the value of the current flowing through the field coil FC1 that constitutes a part of the aforementioned motor M1. The field current control circuit 22 controls the value of the current flowing through the field coil FC2 that constitutes a part of the aforementioned motor M2.

FIG. 2 is an illustrative diagram showing the contents of a data table preset in the ROM 19 shown in FIG.

In the figure, this data table 19 includes each motor M.
A reference field current value Tr that should be passed through the field coil of each motor when motors 1 and M2 are operated with approximately equal load sharing is stored. This reference field current 1i 1 r is stored in the form of a data table that is addressed by a combination of the armature il flow value and the accelerator opening degree. That is, w from 0 to 255A
i Once the accelerator opening degree of armature current 0 to 15 is determined, the armature current value ■'' of the corresponding address is read out.

FIG. 3 is an illustrative diagram showing a part of the storage area of the RAM 20 shown in FIG. In the figure, the RAM 20 stores the armature current value IAI detected by the armature current detection circuit 11.
area 20a for storing the armature current value detected by the armature current detection circuit 12; and area 20b for storing the armature current value detected by the armature current detection circuit 12.
including. The RAM 20 also includes an area 20C for storing the average value T ave of the armature current values A1 and IA2, and an area 20d for storing the difference (hereinafter referred to as deviation) Id between the armature currents 1i11A1 and IA2 from the average value l awe.
including. Furthermore, the RAM 20 has a data table 19
I read it from! ! Area 20e that stores the quasi-field current value 1r, area 2 (H) that stores the strongest field current value IFa×, and area 20o that stores the weakest field current value 1rN0. As mentioned above, the strongest field current value is the upper limit of the range in which the motor load correction does not reach a plateau, and the weakest field current value is the lower limit of this range. The magnetic current is the strongest field current 111ri
+ax and the weakest field current value 1. When in the dark with mln, the motor load can be effectively corrected. Furthermore, 11AM20 is the field l to be passed through the field coil FC1.
It includes an area 20h for storing the instruction value IF 1 of the I current, and an area 20 for storing the instruction values I and 2 of the field current to be passed through the field coil FC2.

FIG. 4 is a flowchart for explaining the operation of the CPLJ 15 shown in FIG. Below, Figures 1 to 114
The operation of an embodiment of the present invention will be described with reference to the drawings.

First, in step 1 (abbreviated as S in the illustration) in FIG. 4, the accelerator opening (AGO) determined by the accelerator opening detection circuit 16 is input.

Furthermore, armature current values IAI and IA2 detected by armature current detection circuits 11 and 12 are input.

Next, in step 2, the armature current values ■A1 and ■ obtained in step 1 are determined.

The average value and deviation of the armature current are calculated based on 2. That is, the average value 1 aV8 and the deviation (d) of the armature current are calculated by the following formula.

rave -(IA I+■A2)/21d-11A
1 1A 21/2 Next, in step 3, armature current values IAI and IA2
It is determined whether or not they are approximately equal. If the armature current values IA1 and IA2 are approximately equal, a field current instruction value is determined from the data table 19 in step 4. That is, the contents of the data table addressed by the average value I ave calculated in step 2 and the accelerator opening degree ACC input in step 1 are stored in the area 20h of the RAM 20 as the field current command value 1r 1 and IF 2. and set to 20+. Then, in step 5, the field current command values 1r1 and Ir2 set in the areas 20h9- and 201 are set to the field current control circuits 21 and 22, respectively.
and the field *F of field coils FC1 and Fe2
M is corrected.

On the other hand, in step 3 described above, armature current value IA1
If it is not determined that OJ: and IA2 are approximately equal, it is determined in step 6 whether armature current 4111A1 is greater than IA2. Armature current III E1 is I
If it is larger than A2, proceed to step 7. In step 7, the field current command values It1 and Ir2 are calculated by the following equations.

It 1=L (TaVB, ACC)+k IdI
t2=Ir(1ava,AGO)kI
dNote that k is a constant determined by the driving characteristics of the electric vehicle, etc., and is determined in advance through experiments. As is clear from the above calculation formula, the field current instruction value It1 is the reference field current instruction value obtained from the data table 19, which is further strengthened by kId. Conversely, the field current instruction value Ir210- is the reference field current value obtained from the data table 19, which is roughly weakened by kid.

Next, in step 8, the field current instruction value Ir 1 obtained in step 7 is stored in 1 rear 20f of the RAM 20.
It is determined whether or not the strongest field current value {circle around (2)}, laX, which is set in advance, is greater than the strongest field current value (2), laX. Field current instruction value Ir 1 is the strongest field current value 1. If it is determined that it is larger than laX, the field current instruction value is changed in step 9. That is, it is calculated in step 7 above and is stored in RAM2.
Field current instruction value 1r set in area 20h of 0 1
However, the strongest field current value is forcibly set to 1. Rewritten to laX. In addition, field current instruction value 1 set in area 201
r 2 is rewritten as in the following equation.

IF2-IF2 (IFI Ir1aX) Note that Ir2 and IF1 on the right side of the above equation are the field current instruction values calculated in step 7 above. Also,
Ir2 on the left side of the above equation is the field current instruction value after the change.As is clear from the above equation, the field current instruction value Ir 1
The field current instruction value 1r2 is weakened by the same amount as the field current instruction value 1r2 is weakened. Subsequently, in step 5, the changed field 1i current command values ■r 1a3 and Ir 2 are applied to the field current control circuits 21 and 22, respectively, to correct the field current.

On the other hand, in step 8 described above, the field current instruction value Ir
1 is smaller than the strongest field i%i current value Ir■a×, proceed to step 10, this step 10
Then, the field current instruction value It2 calculated in step 7 and set in the area 201 of the RAM 20 is
The preset weakest field 1l in area 20Q of M20
It is determined whether the li current value is smaller than the li current value 1, 1n. If the field current instruction value It 2 is the weakest field 1 [current value 1r
If it is smaller than lln, the field current instruction value is changed in step 11. That is, the field current instruction value Ir
2 is the weakest field current value 1. It is forcibly rewritten to sln.

Further, the field sI flow direction instruction value r1 is rewritten as shown in the following equation.

It 1 = Ir 1 + (Ir Win - Ir 2) As clearly seen from the above equation, the field current instruction value IF 1 is increased by the amount that the field current instruction *1r2 is increased by the change. Subsequently, in step 5, the field current is corrected based on the changed field current value. Step 10 above
, the field current command value 1r 2 is the weakest field current!
If it is determined that the value is larger than 111rsln, the field current instruction value is not changed and the field current is corrected in step 5. That is, in step 7, the field current is corrected based on the field current instruction value calculated by ffl in J3.

On the other hand, if it is determined in step 6 that the armature current value IAI is smaller than ■A2, the process proceeds to step 12. In step 12, the field current instruction value is calculated in the same manner as in step 7 described above. In this case, the field current instruction value 1r1 is the reference field current value obtained from the data table 19, which is further weakened by kId. In addition, the field current instruction value 1r2 is data table 1
The reference field current value obtained from 9 is further strengthened by kld.

13- Next, in step 13, it is determined whether the field current command values I, 2 are larger than the strongest field current values 1, 1laX. If the field current command value IP2 is larger than the strongest field current value Ir1lax, the field current command value is changed in step 14. In other words, the field current instruction value IF 2 is forcibly set to the strongest field current)
Changed to rsax. In addition, the field 1mIm phase flow value rr
1 is changed as shown in the following equation.

Ir 1-Ir 1-(Ir 1-It Penga
x) As is clear from the above formula, the field current instruction value 1r
1 can be kept by the amount that the field current instruction value Ir2 is weakened by the change. Thereafter, in step 5, the field current is corrected based on the changed field current instruction value. On the other hand, if it is determined in step 13 that the field current instruction value 1r2 is smaller than the strongest field current value ■, laX, the field current instruction value 11 is determined in step 15.
It is determined whether F1 is smaller than the minimum field weakening current value 1rlin.

If the field current instruction 111r1 is the weakest field current value Ir
If it is smaller than 1ln, the field current command value is changed at step 16 by -14=. That is, the field current instruction value IF 1 is forcibly changed to the weakest field current value 1rNn. Further, the field current instruction value Ir2 is changed as shown in the following equation.

Ir 2=Ir 2+ (Ir 1lln Ir 1
) As is clear from the above equation, the field mm*mallr2 is strengthened by the change that increases the field current instruction value Ir1. Subsequently, in step 5, the field current is corrected based on the changed field current instruction value. On the other hand, if it is determined in step 15 that the field current instruction value Ir 1 is larger than the weakest field current WMI, sin, the field current instruction value is not changed and the field current is corrected in step 5. .

As described above, in one embodiment of the present invention, one of the field current command values calculated in step 7 of FIG. 4 is the strongest field current value 1. sa× or more or the weakest field current value 1. Even if it becomes less than Win, one of the field current command values is forcibly set to the strongest field current value Ir■a× or the weakest field current value 1. Since the value of the field lit current is changed to i+tn, the value of the field lit current is always within the range where effective correction can be made (that is, within the range defined by the strongest field current wilrllaX and the weakest field current value Ir1ln). The amount of correction for the motor load does not reach a ceiling as in the conventional case. Roughly speaking, since the field current on the other side is increased or decreased by the amount of change in the field current value on one side, the relative load correction amount increases and the load sharing between each motor M 1 dXj and M2 is rapidly reduced. It can be made uniform.

Note that in the above embodiment, two motors M1 and M2
Although a case has been described in which three or more motors are operated in parallel, the present invention can also be applied to a case in which three or more motors are operated in parallel.

As described above, according to the present invention, the field m current value to be passed through each motor is determined based on the average value of the armature currents of at least two malls operating in parallel and the difference from the average value. When the current value is greater than or equal to a predetermined upper limit value or less than a predetermined lower limit value, the field current value to be applied to the corresponding motor is forcibly set to the upper limit value or lower limit value.
The field current can always be kept within the range specified by the upper and lower limits, and the motor load can be efficiently corrected without reaching a ceiling unlike in the past. . In addition, the field current value of the other motor is further increased or decreased by the change in the field current setting of one motor for which the upper limit or lower limit value has been forcibly set, so the relative load correction amount increases, and the load on the motor can be quickly equalized.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is an illustrative diagram showing the setting contents of the data table 19 shown in FIG. 1. Figure 3 shows the JRAM20 shown in Figure 1.
FIG. FIG. 4 is a flowchart for explaining the operation of the CPL 115 shown in FIG. In the figure, 1 is a DC power supply, Ml and M2 are motors,
A1 and A2 are armatures, FCl and Fe2 are field coils, 5)-11 and SH2 are shunt resistors, 11 and 12 are armature current detection circuits, 15)
is a CPU, and 21 and 22 are field current control circuits. Patent applicant: Daihatsu Motor Co., Ltd. 18- Ryo 1 Close Ryo 4

Claims (1)

[Scope of Claims] In an electric vehicle in which at least two electric motors each having at least a shunt field are operated in parallel and are driven, means for detecting armature currents of the at least two electric motors; and the detecting means. means for determining the average value between each armature current and the difference of each armature current from the average value based on the detection result of determining means, and increasing or decreasing the field current of each electric motor based on the value of the field current determined by the determining means to equalize the load sharing of each electric motor. means for determining whether the value of the field current determined by the determining means is greater than or equal to a predetermined upper limit or less than a predetermined lower limit; means for forcibly setting the value of the field current to be passed through the corresponding electric motor to the upper limit value or the lower limit value in response to determining that the field current is below the value, and the setting being changed by the forced setting means. Depending on the decrease or increase in the field iI current of one of the motors as a result of
An electric motor control device for an electric vehicle, comprising means for further decreasing or increasing a field current value determined for the other electric motor.