JPS6077612A - Controlling method of electric railcar - Google Patents

Abstract

PURPOSE:To enable to rapidly start an electric railcar from the state of stopping time and zigzag time irrespective of the route state by setting the slip frequency from the start to an ordinary reference slip frequency. CONSTITUTION:When an inverter start command signal 10 is inputted, a switch 4 is shifted from ''0'' side to ''1'' side. Thus, the value FXP produced by adding a reference slip frequency to the rotating frequency of an induction motor is outputted as an inverter frequency 18. When the inverter is started, the output V of the inverter is raised from 0 voltage to the value corresponding to the inverter frequency FXP at that time. If the induction motor current value IM becomes equal to the current limit value IP of the target current value of the induction motor, the output of a comparator 3 becomes ''1'', a constant current control 20 is started, and further shifted to V/F constant pattern operation.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a variable voltage variable frequency inverter (hereinafter referred to as VVV
The present invention relates to a method for controlling an electric vehicle driven by an induction motor controlled by an F-inverter.

[Technical background of the invention and its problems] FIG. 1 is a conventional control flowchart at the time of starting an electric vehicle by controlling an induction motor core using a VVVF inverter. Also, FIG. 2 shows the time t in this case.
The relationship of each frequency to is shown.

Conventionally, when the inverter start command signal @10 is input, the value obtained by adding the start-up slip frequency 12 to the induction motor rotation frequency vI (FR) 11 at start-up is input to the sampling and hold circuit 14 immediately before the switch 13 is switched. Ru. When the switch 13h is switched to the "1" side, a closed loop is formed with the sampling and hold circuit 14, so that the startup inverter frequency (FIPl) 15 is kept constant based on its bold value.

When the ratio V/F between the inverter output voltage V and the inverter output frequency F is kept constant, constant 1-lux control is achieved. When performing this constant torque control, the secondary current I of the induction motor
The R and Zuberry frequency FS are in a proportional relationship, and the reference slip frequency 16 is set to FS from the current limit value pattern showing this proportional relationship.
It can be defined as l.

In FIG. 2, the slip frequency FS is FS=FIP1-FR from startup to time t.

From startup to time 11, constant current control is performed using the inverter output voltage V. Therefore, the torque T during this period is T
=K (IR)2 /FS (K is a constant), so
When the induction motor rotation frequency FR at startup is small and the slip frequency FS is large, the torque T is small, and as FR gradually increases, the torque gradually increases, allowing the electric car to be soft-started. . Roughly speaking, the comparator 17 compares the value FXP=F'R+FS1, which is the sum value FXP of the induction motor rotation frequency FR after startup and the reference slip frequency FSI, with the inverter frequency FIP1 at startup. Comparatively, if FXP>FIPI, the switch 19 turns on at this point, so the inverter frequency 18 switches from FIPI to the value of FXP, starts constant current control 20 based on the slip frequency, and shifts to V/F constant pattern operation 21. and move on.

According to this control, when the route conditions are flat or on a downhill slope, a rough 1-start of the electric vehicle is effective, and very smooth acceleration can be achieved. However, starting on an uphill slope requires high torque from the electric motor at startup, and with the above-mentioned control, the torque was too low, and depending on the slope of the route, the electric car could not start moving at all. Furthermore, even if the electric car starts moving, it will accelerate very slowly, and if a pulse with an extra high frequency is used for starting, such as in inverter pulse width modulation control, it will take a long time to start, and the inverter will Thermal conditions for the switching element become severe.

In this way, if you keep the inverter output frequency constant and wait for the induction motor rotation frequency to rise when starting the inverter, the above problems will occur when starting up on an uphill slope that requires a high 1-lux. there were.

[Object of the Invention] The object of the present invention is to provide an electric vehicle that is capable of quickly starting an electric vehicle driven by an induction motor controlled by a VVVF inverter from a stopped state or meandering state regardless of route conditions. It is intended to provide a control method.

[Summary of the Invention] The electric vehicle control method according to the present invention sets the slip frequency of the induction motor to a steady reference slip frequency from the time of starting the inverter, and sets the input current of the induction motor to a limit determined by the weight of the electric vehicle using the inverter output voltage. By controlling the electric vehicle to start up to the current value, the soft start of the electric vehicle is maintained, and the electric vehicle is quickly accelerated or decelerated after the inverter is activated.

[Embodiment of the Invention] The present invention will be described below based on an embodiment shown in the drawings. In FIG. 3, when the inverter start command signal 10 is input, the switch 4 is switched to b. As a result, the induction motor rotation frequency (FR
)11 and the reference slip frequency (FSI) 16, FXP=FR+FS1, is output as the inverter frequency 18. Furthermore, when the inverter is started at the same time, the inverter output voltage (2) increases from 0 volts toward a value corresponding to the inverter frequency FXP at that time. As the inverter output voltage V rises, the induction motor current value (IM) 2 also begins to rise, and when it becomes equal to the current limit value (IP>1, which is the target current value of the induction motor drive), the output of the comparator 3 becomes '1 '', the output of the AND circuit 5 becomes 1'', the constant current control 20 is started, and the operation gradually shifts to a constant V/F pattern operation.

FIG. 4 shows the relationship between time t at startup and each frequency F according to the present invention.

When the inverter starts, the inverter output voltage V increases until it reaches a predetermined V/F value. During this time and thereafter, the slip frequency FS of the induction motor is equal to the reference slip frequency FSI, and is constant as FS=FS1.

The torque T of an induction motor is expressed as follows, where K is a constant and T-K (V
/FXP)2 - Since it is FS, the torque T increases in proportion to the square of the value of V/FXP from the time the inverter starts until time t1. After t=t1, when the V/F constant pattern and constant current operation starts, the torque becomes constant and the speed increases with constant acceleration.

As described above, according to the method of the present invention, even if the rotational frequency of the induction motor does not increase after startup, the slip frequency is set to the steady reference slip frequency from the beginning, so the advantage is that the rated torque can be produced immediately when the current starts up. There is. Therefore, it is possible to quickly start the electric vehicle from a stopped or coasting state regardless of route conditions. Also, 0
〈[〈Soft start is also possible depending on how the inverter frequency ■ is raised in the tl region.

The above has all explained the method of starting the inverter during power running, but the same can be said about the method of starting the inverter during regeneration.

However, in the case of regeneration, the frequency relationship may be such that FXP-FR-FSl, which is obtained by reducing the reference slip frequency FS1 from the rotational frequency FR of the induction motor, is output as the inverter frequency.

[Effects of the Invention] As described above, according to the present invention, after starting the inverter,
Even when the rate of increase in the rotational frequency of the induction motor is extremely slow, such as when traveling uphill, it is possible to maintain a soft start and quickly generate the necessary torque. This makes it possible to quickly accelerate electric vehicles in a short time, especially in VVVF inverters using pulse width modulation control, even in low-speed regions where the switching frequency is high and the thermal conditions for the switching elements are severe, and even on uphill slopes. It is possible to provide an electric vehicle control method that makes it possible to

[Brief explanation of the drawing]

Figure 1 is a flowchart-like block diagram to explain the conventional control method when starting an induction motor-driven electric vehicle using a variable voltage variable frequency inverter, and Figure 2 is the relationship between the control time and each frequency in Figure 1. FIG. 3 is a block diagram showing an embodiment of the electric vehicle control method according to the present invention in terms of 70-gear 1, and FIG. 4 is a diagram showing the relationship between frequency and control time in FIG. 3. and FIG. 6 is a diagram showing the relationship between the ratio of inverter voltage and frequency. 1... Current limit value, 2... Induction motor current value, 4.13
゜14.19...Switch, 5...AND circuit, 1
0...Inverter start command, 11...Induction motor number rotation frequency, 12...Slip frequency at startup, 15...
Inverter frequency at startup, 16... Reference slip frequency, 3° 17... Comparator, 18... Inverter frequency, 20... Constant current control, 21... V/F constant pattern operation. Applicant's representative Patent attorney Takehiko Suzue Figure 2 Q tl β-Tojiri Figure 4

Claims (1)

[Claims] In an electric vehicle driven by an induction motor controlled by a variable voltage variable frequency inverter, when starting the induction motor, a reference slip frequency is added to the rotational frequency of the induction motor when traveling, and when regenerating. The subtracted value is used as the output frequency of the variable voltage variable frequency inverter from the time of startup, and the value of the variable voltage is set as the output frequency of the variable voltage variable frequency inverter at the time of startup, and the value of the variable voltage is set as the output frequency of the variable voltage variable frequency inverter at the time of startup until the value of the input current of the induction motor rises to the current limit value determined by the weight of the electric vehicle. An electric vehicle control method characterized in that control is performed using an output voltage of a frequency inverter.