JP3582153B2 - Motor control device for electric vehicles - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a traveling motor control device for an electric vehicle, and more particularly to a traveling motor control device capable of preventing an excessive current output from a battery or an excessive current input to a battery.
[0002]
[Prior art]
In an electric vehicle, the occupant is notified of the running limit by displaying the remaining capacity of the battery, etc.However, in actual driving, sudden depression of the accelerator may require excessive current supply from the battery to the driving motor. is there. In this case, if the battery discharge has progressed to some extent, the battery voltage rapidly drops to the discharge end voltage with respect to the requested current, making it impossible to take out the current from the battery and making it impossible to drive. is there.
[0003]
Therefore, for example, in Japanese Patent Application Laid-Open No. Hei 5-328531, a battery output voltage is detected and a state of charge of the battery is roughly predicted. When the battery output voltage falls below a predetermined value, a current supply command value from the battery to the motor is reduced. There has been proposed a method in which a restriction is applied to prevent a drop to a discharge end voltage, thereby avoiding the inability to travel.
[0004]
[Problems to be solved by the invention]
However, the battery output voltage fluctuates depending on many factors such as the total output current from the full charge of the battery, the output current from the battery per unit time, and the ambient temperature. In particular, in the case of the Ni-MH battery, the change in the output voltage with respect to the remaining capacity is small, which is conspicuous. Further, when a large current is taken out from the battery at the time of starting the vehicle, for example, the output voltage of the battery sharply decreases, so the current supply command value to the motor is limited based on the battery output voltage. The device has a problem that the current supply is often limited even when the remaining battery capacity still has a sufficient margin before reaching the discharge end voltage, and the acceleration performance of the vehicle is impaired.
[0005]
It is known that when the current output (discharge) per unit time from the battery becomes excessively large than the capacity determined by the type and capacity of the battery, the discharge characteristics of the battery are permanently deteriorated. .
The present invention solves such a problem, and can appropriately supply a current from a battery to a traveling motor to prevent a situation in which the vehicle cannot be traveled without significantly impairing the acceleration performance, and can prevent the battery from being permanently damaged. An object of the present invention is to provide a traveling motor control device for an electric vehicle that can avoid deterioration.
[0008]
[Means for Solving the Problems]
To achieve the above object, according to the first aspect of the present invention, there is provided an electric vehicle for controlling a traveling AC motor (2) connected to a battery (1) by power supply lines (3A, 3B). In the traveling motor control device, a current command means (71) for commanding an amount of current flowing through the power supply line in accordance with an operation of a driving operation means (51, 52); Inverter means (6) for performing conversion and controlling the current of the AC-side power supply line (3B) in accordance with a command from the current command means, and first voltage detection means (8) for detecting the line voltage of the DC-side power supply line ), Second voltage detecting means (9A) for detecting a line voltage of the AC side power supply line, current detecting means (9B) for detecting a current flowing through the AC side power supply line, and rotation of the AC motor. Number of rotation detection to detect the number A stage (10), the voltage detected by the first voltage detection means and the voltage detected by the second voltage detection means, the current detected by the current detection means, and the rotation speed detected by the rotation speed detection means. Current limiting means for calculating a current flowing through the DC-side power supply line in consideration of the conversion efficiency of the inverter means, and limiting a command current amount from the current command means when the calculated current exceeds a predetermined value ( 308, 309, 310, and 311).
[0009]
According to a second aspect of the present invention, in the traveling motor control device for an electric vehicle according to the first aspect , the current limiting unit is determined according to a degree of the calculated current exceeding the predetermined value. The present invention is characterized in that the command current amount is limited by multiplying the command current amount from the current command means by a command limit coefficient smaller than 1.
[0010]
In addition, the code | symbol in parenthesis of the said each means shows the correspondence with the concrete means of the Example described later.
[0014]
[Effects of the invention] According to the invention described in claim 1, the feeder current at the time of driving the AC motor is calculated accurately, the proliferation of feeder current command current amount based on which is restricted Can be suppressed. The invention described in this claim is realized simply and inexpensively by using the DC-side and AC-side voltage detection sensors and the AC-side current detection sensors installed in the conventional traveling motor control device. You.
[0015]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
In FIG. 1, a DC power supply line 3A is connected to a battery 1, and the DC power supply of the battery 1 is supplied to the inverter 6 by the power supply line 3A, where it is converted into an AC power supply, and is passed through an AC power supply line 3B. It is supplied to the traveling motor 2.
[0016]
A current detection sensor 3A is provided on the DC power supply line 3A, and an output signal thereof is input to the CPU 71 via the input processing circuit 72 of the motor control device 7. Also, output signals from an accelerator opening sensor 51 for detecting a driver's accelerator pedal operation amount and a shift position sensor 52 for detecting a shift position where a shift knob is operated are also input to the CPU 71 via an input processing circuit 72. .
[0017]
The CPU 71 determines a command current amount to the traveling motor 2 according to a processing procedure described later, and outputs the command current amount to the inverter 6 via the output processing circuit 73. The inverter 6 controls the supply current to the traveling motor 2 based on the command current amount.
That is, the CPU 71 determines the driving motor required for driving the electric vehicle based on the accelerator operation amount of the driver detected by the accelerator opening sensor 51 and the shift position determined by the driver detected by the shift position sensor 52. 2 is determined, and an input current command value to the traveling motor 2 is determined so as to realize the required output torque. Then, the input current command value is appropriately limited according to a procedure described later and output to the inverter 6 via the output processing circuit 73.
[0018]
The processing procedure of the CPU 71 will be described below with reference to the flowchart of FIG. First, in step 101, the output current of the battery 1 is detected, and the detected value is stored in IB. In step 102, if the output current IB does not exceed the upper limit value K4 determined in advance based on the type of the battery, the remaining capacity, etc., the detection result of the accelerator opening sensor 51 and the like The input current command value that satisfies the required output torque of the traveling motor 2 determined on the basis of the above is output to the inverter 6 (FIG. 1) as it is as the command current amount I (step 105), and the process ends.
[0019]
If the output current IB exceeds the upper limit value K4 in step 102, a command limit stored in a map or the like in advance in step 103 based on how much the output current of the battery 1 has exceeded K4 is determined in step 103. The coefficient α6 is determined.
In step 104, the command limiting coefficient α6 determined in step 103 is multiplied by the input current command value that satisfies the required output torque of the traveling motor, which is determined based on the detection result of the accelerator opening sensor or the like, and the command current amount is calculated. I, which is output to the inverter. As shown in FIG. 3, the command limiting coefficient α6 becomes smaller than 1 when it exceeds the upper limit K4, so that the input current to the traveling motor 2 is limited.
[0020]
The effect of the above processing will be described below with reference to FIG.
The output current of the battery 1 of the electric vehicle is mainly consumed by the traveling motor 2. Therefore, a current is rapidly output from the battery 1 when the vehicle starts moving. In particular, when the traveling motor 2 is an induction motor, several times to several tens times of the current is consumed at the time of starting even with the same torque output as compared with the steady state.
[0021]
Therefore, at the time of starting the vehicle, the current that can be output by the battery 1 per unit time, including the current consumed by other accessories, may exceed the current, which causes permanent deterioration of the discharge characteristics. If the remaining capacity of the battery 1 is relatively small, the battery voltage may drop sharply to the discharge end voltage (broken line in FIG. 4).
[0022]
Here, when the output current of the battery 1 exceeds the preset upper limit K4 by the processing of the CPU 71 described above, the input current (battery output current) of the traveling motor 2 is limited (the line in FIG. 4). y) This prevents the battery 1 from deteriorating, and prevents the output voltage from dropping to the discharge end voltage to prevent the battery 1 from discharging (line x in FIG. 4).
[0023]
Further, since the output torque of the traveling motor 2 is smoothly changed by limiting the input current, it is possible to ensure the vehicle acceleration without the driver feeling uncomfortable.
According to the present embodiment, as compared with the conventional method of limiting the current supply to the traveling motor 2 based on the battery voltage, the current supply is affected by the remaining capacity of the battery, the discharge characteristics, the discharge history, the variation between the batteries, and the like. It is possible to always appropriately limit the motor current without using it. Therefore, unlike the related art, there is no problem that the current for the traveling motor 2 is excessively limited and the acceleration performance of the vehicle is greatly impaired.
[0024]
In this embodiment, an AC motor is used as the traveling motor, but a DC motor may be used.
Further, the command limiting coefficient α6 shown in FIG. 3 is an example, and is not limited to this as long as it is optimally determined so that α6 <1 when the battery output current is larger than K4.
(Second embodiment)
FIG. 2 is a block diagram showing the configuration of an apparatus according to a second embodiment of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals. In this embodiment, a voltage detection sensor 8 for detecting the line voltage (battery voltage) of the DC power supply line is provided instead of the current detection sensor of the first embodiment. Note that the voltage detection sensor 8 is generally provided in the traveling motor control device, and does not need to be particularly installed to implement the present invention.
[0025]
The output signal of the voltage detection sensor 8 is input to the CPU 71 via the input processing circuit 72 of the motor control device 7.
The processing procedure in the CPU 71 will be described below with reference to the flowchart of FIG. In step 201, the detected battery output voltage is stored in VB (n). In step 202, the difference between the previously stored battery output voltage VB (n-1) and the current battery output voltage VB (n) is obtained and stored as a change amount ΔVB of the battery output voltage.
[0026]
In step 203, it is determined whether or not the change amount ΔVB does not exceed the upper limit value K7 determined in advance based on the type of the battery, the remaining capacity, etc., without deteriorating the discharge characteristics of the battery 1. The input current command value that satisfies the required output torque of the traveling motor, which is determined based on the detection result of the opening degree sensor and the like, is output as the command current amount I (step 205) to the inverter 6 (FIG. 5) as it is, and the process is performed. To end.
[0027]
If the battery voltage change amount ΔVB exceeds the upper limit value K7 in step 203, the degree of the voltage change amount ΔVB exceeding the upper limit value K7 is stored in a map or the like in advance according to the relationship shown in FIG. The determined command restriction coefficient α9 is determined.
Next, in step 204, the command limiting coefficient α9 is multiplied by the input current command value to obtain a command current amount I, which is output to the inverter 6. As shown in FIG. 5, the command limiting coefficient α9 becomes smaller than 1 when it exceeds the upper limit K7, so that the input current to the traveling motor 2 is limited.
[0028]
According to the above processing, the present embodiment has the same effect as the first embodiment. That is, in the present embodiment, the transient output current change of the battery is represented by the product of the output current change and the internal resistance of the battery determined by the battery type and the remaining capacity before electrode deterioration. When the amount of change in battery voltage exceeds a preset upper limit, the input current of the traveling motor is limited.
[0029]
As a result, the output current of the battery is limited, the permanent deterioration of the discharge characteristics is prevented, and, for example, as shown in FIG. The vehicle can be properly maintained (solid line in the figure), and the vehicle can be prevented from running improperly.
In the present embodiment, since a conventionally provided voltage detection sensor can be used, an operation in software is required, but the entire apparatus can be realized simply and inexpensively.
[0030]
Further, the command restriction coefficient α9 shown in FIG. 7 is an example, and the command restriction coefficient α9 is not limited as long as it is optimally set so that α9 <1 when the output voltage change amount of the battery is larger than K7.
(Third embodiment)
FIG. 9 shows a block diagram of the device according to the third embodiment of the present invention. In the present embodiment, in addition to the voltage detection sensor of the second embodiment, a current detection sensor 9B and a voltage detection sensor 9A for detecting the current (motor current) and the line voltage (motor voltage) of the AC power supply line 3B are provided. In addition, a motor rotation detection sensor 10 is provided in the traveling motor 2. Output signals of these voltage detection sensor 9A, current detection sensor 9B, and motor rotation detection sensor 10 are input to CPU 71 via input processing circuit 72.
[0031]
The voltage detection sensor 9A, the current detection sensor 9B, and the motor rotation detection sensor 10 are usually provided in a conventional traveling motor control device because of the need for motor rotation control.
The processing procedure in the CPU 71 will be described below with reference to the flowchart of FIG.
[0032]
In step 301, the motor current of the traveling motor 2 is detected and stored in IM, and in step 302, the motor voltage is detected and stored in VM. Further, in step 303, the number of motor rotations is detected and stored in NE. In step 304, the phase difference の between the motor current IM and the motor voltage VM is detected, and subsequently, the input power PM to the traveling motor 2 is calculated using the phase difference ψ, the motor current IM, and the motor voltage VM. (Step 305).
[0033]
Next, at step 306, the battery voltage is detected and stored in VB. In step 307, the conversion efficiency η of the inverter shown in FIG. 11 stored in advance in the map is determined using the motor speed NE and the motor input power P as parameters. In step 308, the output current IB of the battery 1 is calculated from the input power PM, the battery voltage VB, and the conversion efficiency η.
[0034]
In step 309, it is determined whether or not the calculated battery output current IB does not exceed the upper limit K10 which does not degrade the discharge characteristics of the battery 1 and which is predetermined by the type of the battery, the remaining capacity, and the like. If not, the process proceeds to step 312, where the input current command value that satisfies the required output torque of the traveling motor 2 determined based on the detection result of the accelerator opening sensor or the like is used as the command current amount I, and the inverter 6 (FIG. 9), and the process ends.
[0035]
If the battery output current IB exceeds the upper limit value K10 in step 309, in step 310, how much the battery output current IB has exceeded the upper limit value K10 is stored in a map or the like in advance according to the relationship shown in FIG. The determined command limit coefficient α12 is determined.
In step 311, the command limiting coefficient α12 determined in step 310 is multiplied by the input current command value to obtain a command current amount I, which is output to the inverter 6. As shown in FIG. 12, the command limiting coefficient α12 becomes smaller than 1 when it exceeds the upper limit K4, so that the input current to the traveling motor is limited.
[0036]
In the present embodiment, since the battery current is calculated, the current limit can be performed more accurately than in the second embodiment, and the voltage detection sensors 8, 9A and the current detection sensor 9B are conventionally provided. Can be used, so that it can be realized more simply and inexpensively than in the first embodiment.
Since the conversion efficiency η of the inverter 14 shown in FIG. 11 actually varies depending on the output voltage of the battery, a different conversion efficiency map may be provided for each battery output voltage.
[0037]
Further, when a PI control operation is performed on the deviation between the command current amount I calculated by the CPU 71 and the motor current detected by the current detection sensor 9B, and the result is given to the inverter 6 as a motor voltage command value, the voltage detection is performed. The motor voltage command value can be used as the motor voltage VM without the sensor 9A.
In FIG. 10, the input power PM of the traveling motor is calculated in step 305, and the battery voltage VB is detected in step 306. Conversely, the detection of the battery voltage VB is performed first, and the input power PM to the traveling motor is calculated. The calculation of PM may be performed later.
[0038]
Further, the command limiting coefficient α12 shown in FIG. 12 is an example, and is not limited to this, as long as it is optimally set so that α12 <1 when the battery output current is larger than K10.
In each of the above embodiments, the command current given to the inverter is multiplied by the command limit coefficient determined according to the battery output current, by multiplying the motor input current command value determined according to the accelerator operation amount of the driver and the like. Although the input current to the travel motor is limited by reducing the amount, the output torque command value of the travel motor may be limited in accordance with the battery output current instead.
[0039]
Further, the input current of the traveling motor may be limited by limiting the amount of change per unit time of the accelerator operation amount of the driver according to the output current of the battery.
Alternatively, instead of or in combination with limiting the input current of the traveling motor, the supply of output current from the battery to the auxiliary machine, such as a temporary stop of the air conditioner (A / C), may be performed.
[0040]
Furthermore, in each of the embodiments described above, the case where the running motor is controlled in the power running mode has been described. However, the present invention is also applicable to the case of the regenerative control when the battery is almost fully charged. By limiting the amount of regenerative current when the input current becomes greater than or equal to a preset value, overcharging of the battery can be prevented.
[0041]
The steps in each flowchart in each of the above embodiments may be realized by a hardware logic configuration as a function executing unit.
[Brief description of the drawings]
FIG. 1 is a block diagram of a traveling motor control device according to a first embodiment of the present invention.
FIG. 2 is a processing flowchart of a CPU according to the first embodiment of the present invention.
FIG. 3 is a graph showing a change in a command limiting coefficient according to a battery output current according to the first embodiment of the present invention.
FIG. 4 is a graph showing a change over time in a battery output voltage and an output current according to the first embodiment of the present invention.
FIG. 5 is a block configuration diagram of a traveling motor control device according to a second embodiment of the present invention.
FIG. 6 is a processing flowchart of a CPU according to a second embodiment of the present invention.
FIG. 7 is a graph showing a change in a command limiting coefficient according to a battery output voltage change amount according to a second embodiment of the present invention.
FIG. 8 is a graph showing a change over time of a battery output voltage according to a second embodiment of the present invention.
FIG. 9 is a block diagram of a traveling motor control device according to a third embodiment of the present invention.
FIG. 10 is a processing flowchart of a CPU according to a third embodiment of the present invention.
FIG. 11 is a graph showing the dependence of inverter conversion efficiency on motor input power and motor speed according to a third embodiment of the present invention.
FIG. 12 is a graph showing a change in a command limiting coefficient according to a battery output current according to a third embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Battery, 2 ... Running motor, 3A, 3B ... Power supply line, 4 ... Current detection sensor, 51 ... Accelerator opening sensor, 52 ... Shift position sensor, 6 ... Inverter, 71 ... CPU, 8 ... Voltage detection sensor, 9A: voltage detection sensor; 9B: current detection sensor; 10: motor rotation detection sensor.

Claims (2)

In a traveling motor control device for an electric vehicle that controls a traveling AC motor connected to a battery by a power supply line,
Current commanding means for commanding the amount of current flowing through the power supply line in accordance with the operation of the driving operation means,
Inverter means provided in the power supply line for performing DC-AC conversion and controlling the current of the AC-side power supply line in accordance with a command from the current command means,
First voltage detection means for detecting the line voltage of the DC power supply line;
Second voltage detection means for detecting a line voltage of the AC-side power supply line;
Current detection means for detecting a current flowing through the AC-side power supply line,
Rotation speed detection means for detecting the rotation speed of the AC motor,
Conversion of the inverter means from each voltage detected by the first voltage detection means and the second voltage detection means, the current detected by the current detection means, and the rotation speed detected by the rotation speed detection means. Current limiting means for calculating a current flowing through the DC power supply line in consideration of efficiency, and limiting a command current amount from the current command means when the calculated current exceeds a predetermined value. Motor control device for an electric vehicle. The current limiting means multiplies the command current amount from the current command means by a command limiting coefficient smaller than 1 which is determined according to the degree to which the calculated current exceeds the predetermined value. The driving motor control device for an electric vehicle according to claim 1 , wherein:

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