JPS6260403A - Controller for electric rolling stock - Google Patents

Abstract

PURPOSE:To utilize battery energy efficiently by limiting armature currents to maximum currents or less where a maximum output from a motor is acquired. CONSTITUTION:A current controller 102 controls power transistors 11, 21 so that command currents (iar*), (if*) and armature currents (ia) and field currents (if) measured by current sensors 13, 23 coincide with each other. A maximum control-current arithmetic circuit 130 computes maximum armature currents IaMAX as a maximum output from a motor on the basis of armature currents ia, field currents if and the number of revolution NM of the motor. A command-current comparator 140 selects a smaller value in the maximum- current command iaMAX and command armature currents (ia*) from a current command appliance 101, and transmits the command armature currents (iar*) over the current controller 102. Accordingly, an electric rolling stock can be operated efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for an electric vehicle used, for example, in an electric vehicle.

[Conventional technology]

FIG. 7 shows a conventional configuration of a driving control device for an electric vehicle using a battery as a power source.

In FIG. 7, battery 1 is a power source for driving electric motor 5. In FIG. The chopping of the power transistor 1) controls the voltage of the motor armature 6, and the chopping of the power transistor 21 controls the voltage of the motor field 7, thereby controlling the output torque of the motor 5. 12.
22 are freewheel diodes for the armature 6 and field 7, respectively. Various sensors 17 detect information such as temperature, which is input to the microcomputer 100 together with the accelerator sensor 18 and the rotation speed pickup 19 of the armature 6 of the motor, and the request of the motor 5 by the current command device 101. A command armature current ia" and a command field current if" corresponding to the output torque are calculated. Current sensors 13 and 23 detect the currents of the armature 6 and the field 7, respectively, amplify them with amplifiers 14 and 24, and then input them to the microcomputer 100. 10
2 is the command current ia* in the current command device 101
, if * and the motor currents ia and if obtained by the current sensor 13.23, feedback control is performed, for example, by PI control. This output is then transmitted to the base drive amplifiers 10, 20 . through which the bases of power transistors 1) and 21 are driven. Also, 2
3 is a power supply fuse, 3 is a power supply contactor, and 4 is an input filter capacitor. 30 is a battery voltage sensor,
Detect the terminal voltage (■) of battery 1. Reference numeral 31 denotes a capacity indicator lamp control circuit for the battery 1, which lights an indicator lamp 32 when the battery terminal voltage detected by the battery voltage sensor 30 decreases to notify the driver's seat of the time to charge the battery 1.

[Problem that the invention seeks to solve]

In an electric vehicle having such a configuration as a driving control device, since a battery is used as a power source, effective use of battery energy is desired in order to secure a mileage per one charge of the battery. Furthermore, the required power performance of the vehicle also requires the limit output of the battery and electric motor.

Figure 2 shows the equivalent circuit of the armature circuit. The electrical maximum output to the motor 5 is determined by the electromotive force Ell of the battery l, the resistance component of the armature circuit (internal resistance rB of the battery 1 + armature resistance ra + wiring resistance rS), and the power transistor 1). It is determined by the voltage drop E0 of the commutator etc. of the electric m5. The voltage equation of the equivalent circuit is: El = Eo + Er + i aRa (1)
Here, Ra=rB+ra+rS, Er is the back electromotive force of the electric motor 5, and the electrical output P9 of the electric motor 5 is P,=iaEγ−(E
++ Eo )ia i a2Ra (2), and the armature current ia that maximizes the electrical output P9 is:
Differentiating equation (2), dPx /dia= (Ea -Eo) -2i
aRa=O I a, Ax = (Ea Eo) / 2 Ra
(3) becomes. Generally, when designing a control device, it is done so that the power performance of the vehicle can be obtained with an armature current ia equal to or less than Ia)IIAX given by equation (3).

However, due to aging of the battery 1 and an increase in battery internal resistances r and B at low temperatures, the resistance Ra in equation (3) increases, and the IaMAX that maximizes the output
may decrease.・Furthermore, at the end of battery discharge, the battery terminal voltage decreases, so conventionally the indicator lamp 32 that indicates battery charging shown in FIG. 6 lights up, but as the battery 1 continues to discharge,
When the battery reaches a discharge state of about 90%, the battery internal resistance γB rapidly increases as shown in FIG. 8, so the resistance Ra rapidly increases and the maximum armature current 12MAX decreases. Therefore, if an attempt is made to increase the armature current ia from the accelerator sensor 18 or the like, the armature current ia may become larger than the maximum armature current 13MAX. As it increases, the motor output will conversely decrease. As a result, the armature current ia is further increased,
As shown in FIG. 6(a), a fatal phenomenon occurs in which the battery 1 is rapidly discharged and the electric vehicle becomes unable to run.

Thus, in devices according to the prior art, the armature current ia
is sometimes used where the armature current IaMAX is greater than the maximum armature current IaMAX, and there is a problem in that the electric vehicle is operated with poor battery energy efficiency.

Therefore, in order to solve the above-mentioned problems, the present invention focuses on the fact that the internal resistance of the battery changes depending on the state of the battery, calculates the resistance of the armature circuit, and lowers the armature current below the maximum current at which the maximum output of the motor can be obtained. The purpose of the present invention is to provide a control device that efficiently utilizes limited battery energy in any battery state.

[Means for solving problems]

A DC power supply, an electric motor for driving an electric vehicle, a current value command means for setting an armature current value of the motor by stepping on an accelerator, etc., and controlling the armature current of the motor to the current value by the command means. A control device for an electric vehicle, comprising: a chopper that connects the DC power source, the electric motor, and the chopper in a closed circuit; calculation means for calculating a maximum armature current that generates the maximum output of the motor by using the internal electromotive force of the DC power supply; limiting means for limiting the chopper to control the chopper;
The object of the present invention is to provide a control device for an electric vehicle.

〔Example〕

FIG. 1 shows a first embodiment of the present invention.

A battery 1 serving as a DC power source is a power source for driving an electric motor 5, and r represents an internal resistance of the battery 1. The chopping of the power transistor 1) controls the voltage applied to the motor armature 6, and the chopping of the power transistor 21 controls the voltage applied to the motor field 7, thereby controlling the output torque of the motor 5. . 12.22 are freewheeling diodes for the armature and field 7, respectively, and transistors 1). 21 is turned off, current continues to flow through the armature 6 and the field 7. 17 is various sensors, such as motor temperature,
It detects information such as power transistor temperature.
Together with the accelerator sensor 18 and the motor rotation speed pickup 19, it is input to the current command unit 101, and a command armature current ia'' and a command field current if'' corresponding to the required output torque of the electric motor 5 are calculated.

13 and 23 are current sensors, each connected to the armature 6.
The current flowing through the field [7] is detected, and after being amplified by the amplifier 14.24, it is manually input to the current controller 102.

The current controller 102 is configured with a control circuit such as PI control so that the armature and field currents measured by the current sensors 13 and 23 match the command currents iaゝr and if'', Feedback control is performed.This output passes through base drive amplifiers 10 and 20 to drive the bases of power transistors 1) and 21 at a predetermined conduction rate.In addition, 2 is a power supply fuse, 3 is a power supply fuse, and 3 is a power supply fuse. A contactor turns on and off a!l, and 4 is an input filter capacitor.

Next, the maximum control current calculation circuit 130 according to the present invention will be explained. This circuit 130 is for obtaining the maximum armature current for obtaining the maximum output of the motor 5.

Therefore, as described above, the voltage equation in the equivalent circuit of the armature circuit shown in FIG. 2 is as follows, similar to the equation (1) above.

Es = EO + Er + 1aRa Here, Ra=r, +ra+r.

Then, the armature current 1a, Ax that maximizes the electric output PE of the motor is T a, Ax
= (Ex Eo) / 2 Ra, and if the battery electromotive force E is a predetermined constant value and E is a constant voltage drop, then due to the armature circuit resistance Ra,
The maximum control current 13MAX can be calculated.

Armature circuit resistance Ra is calculated from equation (1) as follows: Ra = (E
,, -E r) / ia (4) Here, E*+=EB Eo.

The motor back electromotive force Er is Er=, ΦN, (5) where, K: constant N determined by the motor, 4: motor rotation speed Φ: field magnetic flux.

The field magnetic flux Φ is Φ=f (if) (6) and is a function of the field current.

From the above (4 equation, (5 equation), equation (6), Ra = (E
s − to + NM f (if) ) /ia(
7) It becomes ゛.

In other words, from equation (3) above, the maximum armature current IaM
In order to obtain AX, the circuit resistance Ra, motor back electromotive force Er, and field magnetic flux Φ are calculated using equations (4), (5), and (6).

Therefore, the maximum control current calculation circuit 130 is
), the field current if obtained by the current sensor 23 is
The field magnetic flux calculation circuit 131 is composed of a function circuit that calculates the field magnetic flux φ from the field magnetic flux Φ obtained by the field magnetic flux calculation circuit 131 and the motor rotation speed according to the above-mentioned equation (5). 19. The back electromotive force calculation circuit 132 is configured of a multiplication circuit that calculates the motor back electromotive force Er by multiplying the motor rotation speed N, 4 obtained by Battery electromotive force E
, the voltage drop due to the circuit resistance is calculated by a subtraction circuit that subtracts the back electromotive force Er obtained by the back electromotive force calculation circuit 132 from The resistance calculation circuit 133 that calculates the armature circuit resistance Ra from the division circuit that divides by a, as described above (
3) A maximum armature current calculation circuit that calculates the maximum armature current 1aMAX at which the motor reaches maximum output by a division circuit that divides a predetermined voltage by the armature circuit resistance Ra obtained by the resistance calculation circuit 133 according to the formula. It consists of 134. Further, the armature circuit resistance Ra is set to a predetermined resistance Ra"
It is comprised of a comparator 135 that issues an output to turn on the display device 150 for the limp home function when the above conditions occur. In addition, the maximum control current ■a1. lAX is sent to command current comparator 140.

This command current comparator 140 selects the smaller current of the command armature current ia" from the current command device 101 and the maximum control current IaMAX, and applies the modified command armature current ia"r to the current controller. Send to 102. In a state where the maximum control current 1a'MAX is limited, the display device 1
50, and transmits and displays information to inform the driver of the state in which the limit is applied.

Next, the operation of the above configuration will be explained in detail.

The control method for the DC shunt motor 5 shown in FIG. Control is performed by making the armature control power transistor 1) fully conductive and turning on and off the field control power transistor 21 to weaken the magnetic flux of the motor field 7 (there is field weakening control at high rotations).

When the energy of battery 1 decreases and the terminal voltage decreases, control automatically switches the field weakening side in from the armature control area.
Moving to area 61. Therefore, the present invention is applied to the field weakening control region (a state in which the armature control power transistor 1 is fully conductive and the full voltage of the battery 1 is applied to the motor armature 6).

This will be described in an example.

Now, the battery 1 is being charged, and in FIG. 8, the internal resistance of the battery 1 is r! Whenever l is small, the command armature current ia'' of the current command device 101 is the maximum armature current I.
Since it is smaller than aMAX, the commanded armature current ra'' is output from the commanded current comparator 140.

However, as the discharge of the battery 1 progresses, the internal resistance r8 of the battery 1 increases rapidly, resulting in a decrease in the maximum armature current 13MAX. Therefore, in the present invention, the maximum control current calculation circuit 130 calculates the circuit resistance R.
a is calculated to calculate the maximum armature current IaMAX, and the command armature current ia2 is the maximum armature current raMAX.
Even if it becomes larger than , the maximum output of the motor 5 can be utilized because the armature current ia is set to the maximum armature current 13MAX. In this way, optimal operation of the electric vehicle can be achieved depending on the battery condition.

Furthermore, when performing control according to the battery state in the present invention, the battery internal resistance r3 is focused on, and the armature circuit resistance Ra is used to monitor the battery state based on changes in this resistance Ra. The motor rotation speed N, 4, armature current ia, and field current if in equation (7), which are necessary to calculate resistance Ra, are control parameters that are normally used to control electric vehicles, so This can be achieved using only software algorithms without the need for new sensor inputs.

Next, a flowchart of the limp home function including the above processing is shown in FIG.

200 is a conventional processing program, and after inputting the motor rotation speed N of 205, the processing program according to the present invention executes 300.
Start from. After calculating the armature circuit resistance Ra at 310, go to 320 and then turn to FIG. 3, which shows a second embodiment of the invention. 100 is a microcomputer unit (MPU), and FIG. 4 shows a flowchart of the MPU 100. Step 201 includes various sensors (accelerator sensor 18, various sensors (motor temperature, power transistor temperature, etc.) 17, motor rotation speed pickup 19)
In step 202, the current command value is calculated based on the input in step 201, and the command armature current i
a" and the command field current if" are calculated. Next, in step 203, the armature current ia from the current sensor 13 is input, and in step 204, the field current if from the current sensor 23 is input.
is input manually, and in step 205, the rotation speed N from the motor rotation speed pink-up 19 is input.

Furthermore, in step 31) in step 310,
Similarly to the field magnetic flux calculation circuit 131 in FIG. 1 (6)
The field magnetic flux Φ is calculated by the formula, and in step 312, the electric motor 5 is
The back electromotive force of
Calculate the circuit resistance Ra using the formula.

Then, the process goes to step 320, and it is determined whether the resistance Ra obtained in step 310 is greater than a predetermined resistance value Ra. If YES, the internal resistance r of the battery 1 increases, and the remaining energy Since this indicates that the battery 1 is low, a lamp or the like requesting charging of the battery 1 is displayed on the display device 150, and the limp home function is performed.Then, the process goes to step 340.If NO, the process goes to step 340. , similarly to the maximum armature current calculation circuit 134 in FIG. The command armature current ia" calculated in step 202 based on the sensor information is compared with the maximum armature current 12MAX. If ia''>IaMAX, the answer is YES, and in order to limit the current to optimally utilize battery energy, the process goes to step 353, displays that the current limit has been executed, and sets the command current ia''r to the maximum armature current. I
If it is smaller than aMAX, the answer is NO and step 352
Then, the command current ia"r is set as the command armature current ia", and the process goes to step 360.

This completes the process according to the present invention and returns to step 206.

Next, in step 206, the command current ia"r obtained in step 350 and the armature current i obtained in step 203 are combined.
A, the command current if, and the field current if obtained in step 204 are controlled so that the field current if obtained in step 204 is controlled, and in step 207, transistor 1). A predetermined duty for driving the base of 21 is output.

When the control state of the motor shifts from the field-weakening control region to the armature control region, there is no practical problem as long as the last calculated armature circuit resistance Ra is held in the field-weakening control region. . Regarding the maximum control current TaHAx, in the armature control region, the armature current is amplified with respect to the battery current by the reciprocal of the conduction rate α of the armature control power transistor 1). The maximum control current in the armature control area is the final Ia14AX calculated by =■a1. lAX/α(9
) may be corrected as shown in the formula.

Figure 6 (bl) shows the results of an experiment using the control device according to the present invention. As the current ia increases, the motor output decreases, battery j is rapidly discharged, and the terminal voltage of battery 1 also decreases rapidly, making the electric vehicle unable to run. As shown in Figure 6 (b), the internal resistance r = (residual energy amount of the battery) of the battery 1 limits the current from the 0 point, and displays that the current has been limited, making the battery energy effective. It can be seen that the running time of the electric vehicle has been significantly extended by using the battery.Note that the display requesting charging of the panteri is set to 0 points.

In this example, the minimum armature current value at the time of current restriction is set to a predetermined value in order to ensure the minimum necessary running of the electric vehicle.

In this embodiment, a lamp is displayed to obtain the limb home function, but a meter indicating the remaining battery energy may be activated in response to an increase in armature circuit resistance.

Furthermore, in the above embodiment, the correction was applied only to the field control region where the full battery voltage is applied to the motor armature, and in the armature control region, the value calculated in the field control region was held and corrected. As shown in FIG. 5, the average voltage Ell□ applied to the armature is calculated from the conduction rate α of the armature control power transistor 1) according to the equation aC), and E,l□−αEg
(10) In the above-mentioned formulas (1), (2), (3), and (4), E and I are replaced by E. You can also rewrite it as

〔Effect of the invention〕

As described above, in the present invention, the resistance of the closed circuit is detected by the resistance detection means, and the maximum armature current that generates the maximum output of the motor is calculated based on this resistance and the voltage of the DC power supply. Since the child current is controlled to be below the maximum armature current, even if the resistance of the closed circuit increases and the maximum armature current decreases depending on the battery condition, the motor's armature current is always kept below the maximum armature current. There is an excellent effect of being able to run an electric car efficiently by keeping the following in mind.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram showing a first embodiment of a control device for an electric vehicle of the present invention, FIG. 2 is an equivalent circuit diagram showing the armature circuit in FIG. 1, and FIG. 3 is a control device for an electric vehicle of the present invention. FIG. 4 is a flowchart of the MPU in FIG. 3, FIG. 5 is a characteristic diagram showing the average voltage with respect to the conduction rate of the transistor, and FIGS. 6(a) and (b) 8 is an electric circuit diagram showing the performance of the conventional electric vehicle control device of the present invention, and FIG. 8 is a characteristic diagram showing the internal resistance of the battery with respect to the amount of battery discharge. 1... Battery forming a DC power source, 5... Electric motor, 1
). 2I... Transistor, 1, 3, 23... Current sensor, 18... Accelerator sensor, 19... Motor rotation speed pickup, 101... Current command device, 102
...Current controller, 130... Maximum control current calculation circuit, 131... Field magnetic flux calculation circuit, 132... Back electromotive force calculation circuit, 133... Resistance calculation circuit, 134...
Maximum armature current calculation circuit, 140... command current comparator. Agent Patent Attorney Takashi Okabe YBYS Figure 3 Figure 5 Figure 6 Figure 7 Abyto S (;-ra$ Procedural amendment □ February/Date, 1985 2 Name of invention Electric vehicle control device 3 Relationship with the person making the amendment: Patent applicant 1-1 Showa-cho, Aichi-Yu-shi (426) Nippon Denso Co., Ltd. Representative Kengo Toda 4th Director 1 Showa-cho, Aichi-Yu-shi, 448 Chome 1-5 Date of amendment order Date of dispatch January 26, 1985 6. Column for a brief explanation of the drawings of the specification to be amended. 1 Correct Contents 1] Book, page 22, line 7, after “schematic diagram,” “7th
The figure is an electric circuit diagram showing a conventional electric vehicle control device.
” is added.

Claims (3)

[Claims] (1) A DC power source and an electric motor for driving an electric car,
The DC power source, the electric motor, and the In a control device for an electric vehicle in which a chopper is connected to a closed circuit, the output of the electric motor is determined by a resistance detection means for detecting the resistance of the closed circuit, the resistance obtained by the resistance detection means, and an internal electromotive force of a DC power source. a calculation means for calculating a maximum armature current that generates a maximum of; and a limiting means for limiting the chopper so that the armature current of the motor is controlled to be equal to or less than the maximum armature current obtained by the calculation means; Electric vehicle control device equipped with (2) The resistance detection means includes a field current detection means for detecting a field current of the electric motor, a rotation speed detection means for detecting a rotation speed of the electric motor, and a product of the field current detection means and the rotation speed. a back electromotive force detection means for detecting a back electromotive force of the motor from the field current and rotation speed respectively obtained by the output means; and an armature current detection means for detecting an armature current of the motor; A patent claim characterized by comprising: resistance calculation means for calculating a resistance by calculating a back electromotive force obtained by the electromotive force detection means and an armature current obtained by the armature current detection means. A control device for an electric vehicle according to item 1. (3) The control device for an electric vehicle according to claim 2, which issues a warning when the resistance obtained by the resistance detection means increases to a predetermined value or more.