JPH0480604B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of controlling an electric vehicle that drives a DC shunt motor.

With advances in semiconductor technology, a method of controlling a DC motor with a DC chopper device has been widely put into practical use. Furthermore, recently, in order to increase the degree of freedom in control, improve performance, and further increase effects such as energy saving, methods of separately excitation control of DC shunt motors have been studied.

FIG. 1 is a main circuit connection diagram of an electric vehicle using separately excited control according to the present invention. In the figure, L ₁ and L ₂ are circuit breakers for opening the circuit, FL is a filter reactor,
FC is a filter capacitor, P ₁ and P ₂ are contacts that are closed during power running of the power running brake converter, B ₁ and B ₂ are contacts that are closed during braking, MSL is the main smoothing reactor, and CH
is a chopper device, FWD is a freewheeling diode, EX is an excitation device, F ₁ and F ₂ are contacts that close when the reverse gear moves forward, R ₁ and R ₂ are contacts that close when the reverse gear moves backward, and A is the electric motor. child, SF is the shunt field winding.

If the basic control method is forward, i.e. contact
This will be explained under the condition that F ₁ and F ₂ are closed.

(1) During power running, contacts P ₁ and P ₂ are closed, and the current interrupters L ₁ and
Configure a power running circuit with L ₂ closed. In the constant acceleration control, the field current If is controlled to be constant at a predetermined value by the excitation device EX, and the armature current Ia is also controlled to be constant to a predetermined value by the chopper device CH. At this time, the conduction rate of the chopper device CH changes from the minimum to the maximum, and so-called voltage control by the chopper is performed.

(2) When the flow rate of the chipping device CH reaches the maximum,
When most of the line voltage is applied to the armature, the field current If is gradually reduced to further increase the armature current Ia.
Try to keep it constant. The field gradually weakens and the pulling force decreases, but the speed increases further.

(3) When the field current If decreases to the allowable limit of the motor, If is fixed at that value and the final powering characteristics are entered.

(4) When the power running command disappears, the flow breakers L ₁ and L ₂ are opened and coasting begins.

(5) When a braking command is issued, the circuit is configured by closing contacts B ₁ and B ₂ and closing current interrupters L ₁ and L ₂ again.
In the high-speed range, the conductivity of the chopper device CH is fixed to the minimum, and the field current If is controlled by the excitation device EX to perform regeneration control.

(6) When the field current If reaches a predetermined value after deceleration, If
is fixed, the current flow rate control of the chopper device CH is started, and the current flow rate is increased as the speed decreases to keep the armature current Ia constant, and regeneration control is performed to obtain the necessary braking force at a constant level. Let's do it.

(7) When the current flow rate of the chopper device CH reaches its maximum, the armature current Ia attenuates and the braking force also decreases, so a second brake such as an air brake is used to supplement this, but this is only possible in a narrow area just before stopping. be.

As mentioned above, when armature control by the chopper device CH and field control by the exciter EX are combined,
In addition to power running, regenerative braking control is also possible over a very wide speed range (from high speed to just before stopping).

On the other hand, the field chopper control method, in which the armature current is controlled by a resistance step using a camshaft and the shunt field is controlled by a chopper, can be used to create an energy-saving electric vehicle that can regenerate at a relatively low cost, so there are no practical examples. many. Second
The figure shows the main circuit connection diagram, but the basic control is similar to the system shown in FIG. However, during regenerative braking, the resistance value of the resistor MR is zero, and since there is no control function for the armature voltage (that is, there is no boost function like a chopper), the maximum limit of the field current If is relatively high. The drawback is that the electric braking disappears at high speeds (around 30km/h).

However, this method allows regenerative braking in the high-speed range, and the final circuit for power running (MR = 0) and the main circuit are the same, that is, the transition from power running to braking is continuous by controlling the field current If. It is often used for constant speed operation at high speeds.

The present invention has been made in view of the above, and provides a control method for an electric vehicle that can improve the regenerative braking range, the responsiveness, and the riding comfort.

First, in order to enable constant speed operation similar to that shown in FIG. 2, the chopper device CH shown in FIG. 1 is changed to the configuration shown in FIG. 3 having reverse conduction characteristics. This is a chiyotsupa device
This can be easily realized by adopting a series arc-extinguishing repulsion pulse type using a reverse conduction thyristor in the CH, that is, a chopper circuit. However, since the current rating of the diode region of a reverse conduction thyristor is generally smaller than the rating of the thyristor region, care must be taken regarding current conduction duties. In Figure 3, MCRF is the main thyristor, ACRF is the auxiliary thyristor, CML is the commutation reactor, and CMC
is a commutating capacitor, and it is well known that both MCRF and ACRF have diode characteristics in the opposite direction.

Next, the control method of the present invention will be explained.

(1) Power running is exactly the same as the control described above.

(2) When running at high speeds at or near the final characteristic of power running, perform constant speed operation. That is, if the actual speed is lower than the commanded speed, the field current If is reduced to weaken the field and further accelerate. When the actual speed becomes equal to the commanded speed, adjust If to make the armature current Ia equivalent to a tensile force that balances the running resistance. Furthermore, when the actual speed becomes higher than the command speed due to conditions such as a downhill slope, the field current If is increased while the circuit remains the same, and the armature current -Ia in the opposite direction, that is, the regenerative braking current is applied to decelerate the train. Do it like this. Armature current Ia in this case
Since the current flows backward through the main thyristor MCRF, the magnitude |−Ia| should be within the rating of the main thyristor MCRF diode area. Unlike stop braking, constant speed operation requires only a small braking force, and does not cause any problems with restrictions on the thyristor rating.

(3) Acceleration, coasting, and deceleration in this constant speed operation are all possible by controlling the field current If, but in order to improve riding comfort, the pulling force or braking force can be adjusted by changing the speed deviation. It is best to relate them as shown in Figure 4.

(4) When a large braking force is commanded, such as stopping braking, the brake circuit is switched to the above-mentioned braking circuit to control the flow rate of the chopper device CH in the forward direction, and at the same time,
The excitation device EX controls the field current to apply regenerative braking until just before stopping.

(5) As shown in Figure 5, the following methods can be used to convert the power running circuit (the same applies to braking during constant speed operation) and the braking circuit.

(a) When a braking command is issued for stopping or decelerating, the brake circuit is used, and in all other cases, the power running circuit is used. Therefore, even when a deceleration command is issued from the speed control device during constant speed operation, the circuit is placed in the power running state (see FIG. 5a).

(b) A method of selecting a circuit based on the magnitude of the commanded braking force, regardless of commands for constant speed operation, stop commands, etc. That is, the power running circuit is used to control the small braking force that is often used in constant speed operation, and the braking circuit is used to control the large braking force that is commanded mainly for stopping (see FIG. 5b).

As described above, if the main circuit connection is changed depending on the type of braking command or the magnitude of the commanded braking force, continuity and smoothness of the operation mode transition required for constant speed operation and stop braking can be improved. It is possible to realize a control method that satisfies both the wide range of electric braking action required in the following. Moreover, selection of the above conversion conditions is very simple.

Although Fig. 1 shows a thyristor rectifier control device using three-phase AC power as an excitation device for the shunt field, it is also possible to use a system that excites directly from the overhead contact line with a DC chopper as shown in Fig. 2. It can be anything.

[Brief explanation of the drawing]

FIG. 1 is a main circuit connection diagram showing an embodiment of the present invention;
Figure 2 is the main circuit connection diagram of the field chopper method, Figure 3
The figure is a detailed diagram of the chopper circuit shown in Figure 1, Figure 4 is a speed deviation-pulling force/braking force characteristic diagram during constant speed operation according to the control method of the present invention, and Figures 5a and b are diagrams of the characteristics of the chopper circuit of the present invention. FIG. 3 is a diagram showing main circuit switching conditions according to a control method. In the figure, A is the armature of the shunt motor, F is the field winding of the shunt motor, and CH is the chopper device. Note that the same reference numerals in each figure indicate the same or equivalent parts.

Claims (1)

[Claims] 1 A chopper device having reverse conduction characteristics is connected in series with the armature of a DC shunt motor that drives an electric car, and the chopper device controls the conduction rate and the field current of the DC shunt motor to generate electricity. In a method for controlling a vehicle, a power running circuit is configured by the DC shunt motor and a chopper device to perform power running control and regenerative braking to control the vehicle speed of the electric vehicle to a predetermined command speed, and then stop the electric vehicle. When a braking command corresponding to a large braking force such as braking is issued, a braking circuit is formed in which the armature and the chopper device form a closed circuit by changing the connection of the armature circuit, and the chopper device A method for controlling an electric vehicle, characterized in that the conduction rate is controlled by the above-mentioned field current, and braking is controlled by controlling the field current.