JP2003018703A - Electric vehicle drive control system - Google Patents

Abstract

(57) [Problem] To provide a drive control method for an electric vehicle with high energy efficiency in speed control of an electric vehicle without a speed sensor. SOLUTION: In driving control of an electric vehicle based on a speed calculation value of an electric vehicle obtained by speed calculation means 6, input means 7 for inputting a target speed for constant speed operation, and speed calculation immediately before entering a coasting state. A coasting traveling speed estimating unit 11 for obtaining an estimated coasting speed with the value as an initial value; and a current command generating unit 1 for generating a current command in accordance with a deviation between the target speed and the coasting speed estimated value. Deviates from the predetermined range, the current command is given for a short time, and the power converter 3 is restarted intermittently during the coasting state of the electric vehicle. Here, the coasting traveling speed estimating means comprises a switch 8, a traveling resistance calculator 9 and an integrator 10, and when the restart command is turned off, the speed calculation value immediately before the restart command is turned off is used as an initial value to estimate the coasting speed estimated value. The estimated value during coasting is obtained by integrating the deceleration corresponding to.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for an electric vehicle, and more particularly to a drive control technique by speed sensorless vector control that does not require a speed sensor attached to an electric motor.

[0002]

2. Description of the Related Art In the control of an electric vehicle, an electric power converter is operated to drive a main motor to accelerate the electric vehicle to a certain speed, and then the operation of the electric power converter is stopped so that the inertia of the electric vehicle is reduced. There is a coasting condition that you leave it to run,
Compared to other transportation means such as automobiles, the running resistance is low and the deceleration in coasting state is small. Therefore, when driving an electric vehicle, the coasting state is positively used to improve energy efficiency. . In addition, the electric power converter used for controlling the drive of the electric vehicle does not always operate, and since natural cooling by running wind can be expected during coasting, there is an advantage that the cooling system can be relatively simple and compact. Further, in the operation of the electric vehicle, there is an operation mode called constant speed operation for keeping the traveling speed constant. By constantly generating a torque sufficient to balance the deceleration due to running resistance, the running speed of the electric vehicle can be kept constant, but in general, from the viewpoint of energy efficiency, the set speed for constant speed operation is set. In many cases, an allowable range is provided, and within that range acceleration and coasting are repeated. By the way, when the speed sensorless control that does not use the speed sensor is used for the drive control of the electric vehicle, the operation of the power converter is stopped during coasting, so speed information cannot be obtained and constant speed operation in which acceleration and coasting are repeated. There is a problem that can not be realized. As a method for realizing constant speed operation of an electric vehicle by speed sensorless control, for example, Japanese Patent Application Laid-Open No. HEI 1
As described in Japanese Patent Publication No. 1-41986, there is known a method of always obtaining speed information by always operating only one of a plurality of electric power converters forming an electric vehicle formation.

[0003]

In the prior art described in the above publication, only one of the plurality of electric power converters forming the train of the electric vehicle is always operated, and the torque is substantially reduced during coasting. Since it does not need to occur, the current supplied to the main motor can be suppressed, and energy saving is achieved. However, if the number of units of power converters that compose an electric car is small, the effect of energy saving is small,
Further, at least one unit needs to be always operated, but there is a problem that the cooling system must be designed in accordance with the unit which is always operated.

An object of the present invention is to provide a drive control system for an electric vehicle with high energy efficiency in speed control of the electric vehicle without a speed sensor.

[0005]

In order to solve the above-mentioned problems, a speed obtained by an input means for inputting a target speed for constant speed operation and a speed calculation means for calculating a speed of an electric vehicle immediately before entering a coasting state. Providing a running speed estimation means during coasting for obtaining an estimated speed value during coasting with the calculated value as an initial value, and a current command generation means for generating a current command according to a deviation between the target speed and the estimated speed during coasting, and the deviation is When it deviates from the predetermined range, the current command is given for a short time to intermittently restart the electric power converter while the electric vehicle is coasting.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a drive control system for an electric vehicle according to the present invention. The present embodiment is an example of a control method for realizing constant speed operation of an electric vehicle by a speed sensorless vector control method. In FIG. 1, the power converter 3
Supplies three-phase AC AC power to the induction motor 5 based on the three-phase AC voltage command output from the vector controller 2. The vector controller 2 inputs the d-axis current pattern Id *, the q-axis current pattern Iq *, and the estimated speed (power running speed calculation value) F ^ r of the rotation frequency of the induction motor, and the induction motor 5 based on the motor constant. Generate a three-phase AC voltage command to drive the. The current sensor 4 detects a current supplied to the induction motor 5 and outputs a three-phase alternating current Iu, Iv, Iw.
The speed calculator 6 inputs the three-phase AC currents Iu, Iv, and Iw detected by the current sensor 4, and calculates an estimated speed (speed calculation value during power running) F ^ r of the rotation frequency of the induction motor 5 based on the motor constant. Output. The target speed holding means 7 holds the estimated speed (power running speed calculation value) F ^ r of the induction motor 5 at the time when the constant speed operation command is given, and uses this as the target speed for constant speed operation (constant speed operation speed). ) Output as Frh.
In the switch 8, the A contact is on and the B contact is off while the restart command is on, and the A contact is on when the restart command is off.
The contact turns off and the B contact turns on. The speed calculation value F ^ r of the speed calculator 6 is input to the A contact of the switch 8, and its output is connected to the initial value input of the integrator 10. On the other hand, the output of the running resistance calculator 9 is input to the B contact of the switch 8, and the output is connected to the input of the integrator 10. The running resistance calculator 9 outputs the output of the integrator 10 (estimated speed value during coasting) F.
Using ^ r 'as an input, the running resistance corresponding to this F ^ r' is calculated, and the deceleration corresponding to F ^ r 'is output. The running resistance may include the mass and running resistance of the electric vehicle or the gradient in the route section. Current command generator 1
Is an input of the deviation between the constant speed operation speed Frh of the target speed holding means 7 and the output F ^ r 'of the integrator 10 based on the constant speed operation command, and the d-axis current command and the q-axis current are input according to this speed deviation. Output a command. Here, the switch 8, the traveling resistance calculator 9, and the integrator 10 constitute the coasting traveling speed estimator 11, and the speed calculation value F of the speed calculator 6 while the restart command is on.
^ R continues to be set as the initial value of the integrator 10. When the restart command is turned off, the speed calculation value F ^ r immediately before the restart command is turned off is used as an initial value, and the deceleration corresponding to the speed estimate value F ^ r 'during coasting is integrated.
We are looking for ^ r '.

FIG. 2 shows details of the current command generator 1 shown in FIG. The hysteresis-equipped comparator 20 receives the deviation between the constant speed operation speed Frh and the coasting speed estimated value F ^ r '. The hysteresis-equipped comparator 20 is a comparator (comparator) that has different conditions for switching the output from on to off and conditions for switching the output from off to on. Specifically, the speed deviation as an input is a speed deviation in constant speed operation. When it becomes larger than the lower limit value Fra of the range, that is, when the estimated speed value F ^ r 'during coasting reaches the lower limit of the speed deviation range of constant speed operation (F ^ r'<Frh-Fra), the output is turned on. To do. When the speed deviation becomes smaller than the upper limit value -Frb of the speed deviation range of constant speed operation, that is, when the coasting speed estimation value F ^ r 'reaches the upper limit of the speed deviation range of constant speed operation (F ^ r '> Frh + Frb), turn off the output.
The AND (logical product) element 21a receives the output of the constant speed operation command and the comparator 20 with hysteresis, and turns on the output only when both inputs are on. The one-shot trigger 22 receives the output of the AND element 21a as an input and turns on the output for a predetermined period Tres from the moment the input is turned on (rising edge). The OR (logical sum) element 24 receives the output of the AND element 21a and the output of the one-shot trigger 22, and turns on the output when either input is on. The restart command is output from the OR element 24. The NOT element 25 is a one-shot trigger 2
Invert the output of 2. The AND element 21b receives the output of the AND element 21a and the output of the NOT element 25,
The output is turned on only when both inputs are turned on. The switch 23a outputs the d-axis current suppression value Id * res suppressed so that the induction motor 5 does not substantially generate torque when the output of the one-shot trigger 22 is on, and outputs zero when the output is off. To do. Switch 23b is AND
When the output of the element 21b is on, the d-axis current rated value Id *
When 0 is output and is off, the output of the switch 23a is selected. The d-axis current pattern Id * is output from the switch 23b. The switch 23c outputs the q-axis current rated value Iq * 0 when the output of the AND element 21b is on, and outputs zero when it is off. The q-axis current pattern Iq * is output from the switch 23c.

FIG. 3 shows a waveform during constant speed operation of this embodiment. The initial state of FIG. 3 is during power running acceleration (non-constant speed operation), the restart command is on, the d-axis current pattern Id * and q
A predetermined value is given to the shaft current pattern Iq *, and the actual speed Fr
Is monotonically increasing. The power running speed calculation value F ^ r in FIG. 3 is the output of the speed calculator 6 in FIG. 1, and the restart command is on, so the speed estimation calculation is performed with high accuracy. The coasting speed estimation value F ^ r 'is the output of the integrator 10 in FIG. 1, and is the same as the powering speed calculation value F ^ r during restart. At time T1, a constant speed operation command is input, and constant speed operation is performed with the constant speed operation speed Frh at time T1 as the target speed. Even if the constant speed operation command is input, the restart command is turned on for a while, and the d-axis current pattern Id * and the q-axis current pattern Iq * continue to perform powering acceleration with the predetermined values, but at time T2, coasting is in progress. The estimated speed value F ^ r 'is the upper limit of the constant speed operation speed deviation (Frh
When + Frb) is reached, the restart command is turned off, and the d-axis current pattern Id * and the q-axis current pattern Iq * become zero. Since the operation of the power converter 3 is stopped, it becomes impossible to estimate the speed from the detected current value, and the calculated speed value F ^ r during power running becomes zero. The estimated speed value F ^ r 'during coasting is
With the value just before the restart command is turned off as the initial value, the speed is estimated by obtaining the deceleration from the train mass and running resistance of the electric vehicle, but the speed is determined by the gradient conditions in the route section, air resistance, and other factors. Since an estimation error occurs, the estimated speed value Fr ^ 'during coasting reaches the lower limit (Frh-Fra) of the constant speed operation speed deviation before the actual speed Fr. At time T3, when the speed estimation value F ^ r 'during coasting reaches the lower limit of the constant speed operation speed deviation, the restart command is turned on and d is suppressed.
The axis current pattern Id * res is given and the q-axis current pattern Iq * remains zero. Operate the power converter 3,
Accurate speed calculation can be performed by passing a current through the main motor 5, and the power running speed calculation value Fr ^ traces the actual speed Fr with high accuracy. Similarly, the speed estimation error of the speed estimation value F ^ r 'during coasting is also eliminated. As a result of operating the power converter 3 and performing accurate speed calculation, when the actual speed Fr falls within the constant speed operation speed deviation range, the restart command is promptly turned off. At time T4 = T3 + Tres,
When the restart command is turned off and the d-axis current pattern Id * is set to zero, the power running speed calculation value F ^ r becomes zero, and the coasting speed estimated value F ^ r 'is the value immediately before the restart command is turned off again. With the value as an initial value, deceleration is calculated from the train mass and running resistance of the electric vehicle to estimate the speed. Similarly, the restart command is turned on at time T5 and the restart command is turned off at time T6. At time T7, the estimated coasting speed value F ^ r 'reaches the lower limit of the constant speed operation speed deviation range, and when the restart command is turned on, the actual speed Fr also reaches the lower limit of the constant speed operation speed deviation range. , It continues to power running acceleration. At time T8 = T7 + Tres, d
The shaft current pattern Id * is the rated value I from the suppression value Id * res
After returning to d * 0, the q-axis current pattern Iq * is also returned from zero to the rated value Iq * 0, and power running acceleration is started from the coasting state.

In this embodiment, an estimated speed value F ^ r 'during coasting is set with the speed calculation value F ^ r immediately before entering the coasting state as an initial value.
When the deviation between the target speed (constant speed operation speed) Frh and the coasting speed estimated value F ^ r 'deviates from the predetermined range, the current command Id * is suppressed so that the main motor does not substantially generate torque. When res is given for a short time Tres and an accurate speed estimation value is obtained from the motor current, the operation of the power converter is immediately stopped. Such an intermittent current command I
By giving d * res, the running speed of the electric vehicle can be managed within a predetermined range even during coasting, and constant speed operation by speed sensorless control can be realized. That is, when a constant speed operation of an electric vehicle is realized by speed sensorless control, if the vehicle travels strictly at a constant speed, it is necessary to operate the power converter at all times to perform constant torque control and speed control. In the present embodiment, attention is paid to the fact that the constant-speed operation of the electric vehicle is actually operated with an allowable range for the constant-speed operation speed, and the running resistance of the electric vehicle is small and the speed change is small. By intermittently operating the power converter and performing speed estimation calculation, it becomes possible to manage the running speed of the electric vehicle within a predetermined range, and constant speed operation by speed sensorless control even during coasting. Can be realized. If the deceleration due to the running resistance of the electric vehicle is set to a constant value, the interval for operating the power converter intermittently is calculated from the range of the constant speed operation speed deviation, but the running resistance of the electric vehicle is actually Since the term proportional to the speed and the term proportional to the square of the traveling speed are included, in the present embodiment, the deceleration due to the traveling resistance is obtained more strictly,
The frequency and operating time of operating the power converter intermittently are further reduced.

[0010]

As described above, according to the present invention,
When the deviation between the target speed for constant speed operation and the estimated speed value during coasting deviates from the predetermined range, the main motor gives a current command suppressed for a short time so that torque is not generated substantially, and the accurate speed is calculated from the motor current. When the estimated value is obtained, the operation of the electric power converter is immediately stopped, and the current command is intermittently applied, whereby the traveling speed of the electric vehicle can be managed within a predetermined range even during coasting, It is possible to realize constant speed operation by speed sensorless control, and at the same time, drive control of an electric vehicle with high energy efficiency can be performed. Further, by more accurately obtaining the deceleration due to the running resistance of the electric vehicle, it is possible to reduce the frequency and operating time of intermittently operating the power converter.

[Brief description of drawings]

FIG. 1 is an embodiment of a drive control system for an electric vehicle according to the present invention.

FIG. 2 is a detailed diagram of a current command generator of the present invention.

FIG. 3 is a waveform diagram during constant speed operation according to the present invention.

[Explanation of symbols]

1 ... Speed controller, 2 ... Vector controller, 3 ... Power converter, 4 ... Current sensor, 5 ... Induction motor, 6 ... Speed calculator, 7 ... Target speed holding means, 8 ... Switch, 9 ... Running resistance calculation Device, 10 ... integrator, 11 ... coasting speed estimation device, 20 ... comparator with hysteresis, 21a, 21b ...
AND (logical product) element, 22 ... One-shot trigger, 2
3a, 23b, 23c ... switch, 24 ... OR element, 2
5 ... NOT element

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tsutomu Ozawa             1070 Ichimo, Hitachinaka City, Ibaraki Prefecture Stock Association             Hitachi, Ltd. Mito Transportation Systems Division (72) Inventor Eiichi Toyoda             1070 Ichimo, Hitachinaka City, Ibaraki Prefecture Stock Association             Hitachi, Ltd. Mito Transportation Systems Division F term (reference) 5H115 PA11 PG01 PI01 PV09 QN06                       SE03 TO12                 5H576 AA01 BB02 BB06 DD02 DD04                       EE01 EE19 FF03 FF04 GG02                       HB01 JJ03 JJ22 LL12 LL22

Claims (3)

[Claims] 1. An induction motor for driving an electric vehicle, a power converter for supplying AC power to the motor, a current detecting unit for detecting an AC current supplied to the electric motor, and a current detecting unit for detecting the AC current. In a drive control device for an electric vehicle, which comprises speed calculation means for calculating the speed of the electric vehicle from an electric current, and drives and controls the electric vehicle based on the speed calculation value obtained by the speed calculation means, Input means for inputting, a coasting traveling speed estimation means for obtaining a coasting speed estimated value with the speed calculation value immediately before entering the coasting state as an initial value, and a deviation between the target speed and the coasting speed estimated value. A current command generating unit that generates a current command according to the above is provided, and when the deviation deviates from a predetermined range, the current command is given for a short time, and the power conversion is intermittently performed during a coasting state of the electric vehicle. Electric vehicle drive control method, characterized in that to restart. 2. The drive control system for an electric vehicle according to claim 1, wherein the current command is a current value suppressed so that the electric motor does not substantially generate torque. 3. The coasting traveling speed estimating means according to claim 1 or 2, comprising a switch, a traveling resistance calculator and an integrator, and while the restart instruction output from the current instruction generating means is on. , The speed calculation value of the speed calculation means is continuously set as the initial value of the integrator, and when the restart command is turned off, the speed calculation value immediately before the restart command is turned off is set as the initial value and the speed estimation value according to the coasting speed estimation value A drive control method for an electric vehicle characterized by integrating deceleration to obtain an estimated speed value during coasting.