JPS5936518B2 - DC motor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC motor control device, and particularly to a thyristor Leonard type control device suitable for use in vehicles.

In vehicles such as new transportation systems, DC motors are controlled by thyristor Leonard devices.

FIG. 1 shows an example of a field reversal type thyristor Leonard, in which the piezoelectric motor is separately owned.

A field current command section NF generates a field current pattern according to the deviation between the commanded speed Vp and the vehicle speed VT detected by the speed generator TG, and the current flowing through the field F is controlled using the field control thyristor Fth. do. Then, in accordance with the absolute value of this field current, the armature current command section IA generates an armature current pattern, and the current flowing through the armature A is controlled using the armature control thyristor Ath. This is convenient because switching between power running/regenerative braking and forward/reverse driving necessary for speed control of the vehicle can be performed by controlling only the two thyristors Ath and Fth, and direct winding characteristics can be obtained.

However, when we consider the case of performing field weakening control to expand the speed control range, when the armature voltage is detected and exceeds a certain voltage, as shown by the dotted line in the figure.

(1) Lower the field current command value for speed deviation.

(2) Since the armature current will also decrease if left as is, increase the command value of the armature current with respect to the field current. It becomes necessary. Therefore, the armature current command section IA and the field current command section NF need to have coefficient units CIA and CNF.
The circuit becomes complicated. Also, these two coefficient units need to operate in conjunction, but if they fluctuate and, for example, weaken the field current command too much or strengthen the armature current command In order to avoid this, the coefficient multiplier needs to have sufficient accuracy, which may further complicate the coefficient multiplier and lower the overall reliability. Further, even if the field current 1F is excessively reduced when the main motor becomes overspeeded, the armature current IA is not limited, so there is also a risk of deterioration of commutation or flashover. SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a DC motor control device that operates stably with a simple circuit configuration.

In order to achieve this object, the present invention provides an armature current control system in which an armature current command is created from a speed deviation using a speed deviation vs. armature current command section, and a field current command is created from a speed deviation using a field current vs. armature current command section. An armature current command that provides a predetermined minimum field rate is created according to the current, and a low priority section gives priority to the lower of these two armature current command values and outputs it as an armature current command. In the magnetic current control system, the field current command is created from the speed deviation by the speed deviation vs. field current command section, and the armature voltage is controlled to be almost constant from the armature voltage by the armature voltage vs. field current command section. The field weakening control of the DC motor can be performed stably by creating a field current command of The feature is that it is made to be able to be used.

An embodiment of the present invention will be described below with reference to FIG.

The piezoelectric motor is basically based on an armature current control system and a field current control system that are controlled according to the speed deviation Δ (or a notch command may be used).

The armature current control system includes a speed deviation vs. armature current command part NA that creates an armature current command from the speed deviation, and a field current that commands an armature current that provides a predetermined minimum field rate according to the field current. A counter-armature current command section FA is provided, and the lower command values from these two command sections are sent to the lower priority section AL.
is given priority and becomes the armature current command. On the other hand, the field current control system includes a speed deviation vs. field current command section NF that creates a field current command from speed deviation, and an armature voltage vs. field current command section NF that creates a field current command from armature voltage for constant armature voltage control. A field current command section EF is provided, and among the command values from both of these command sections, the lower one is prioritized by the low priority section FL and becomes the field current command. With this configuration, the operation from when the piezoelectric motor is started until it reaches the target speed is shown in FIG. 3.

To simplify the explanation, it is assumed that the speed command is given in seven notches (1N to 7N). In this diagram,
The part a is a 100% field part where the armature control thyristor Ath is not saturated.

In this part a, both the armature current 1A and the field current 1F are given in response to the notch command, and the piezoelectric motor has series winding characteristics. In addition, even if there is a sudden increase in notch commands, the armature current control system with a fast response speed will output first, and the armature current pattern will be changed in the field so that the field current control system is not transiently delayed and rectification deteriorates. It is limited by the magnetic current versus armature current command unit, that is, the field rate limiter FA. Next, part b is a field weakening transition region, and in this part b, the field current is controlled by the armature voltage versus field current command unit so that the armature voltage is kept constant.
In other words, the pattern of the constant armature voltage control section EF becomes low, and control is performed along this pattern.

Therefore, if the armature control thyristor Ath is designed so that it will not be saturated even at this voltage, the armature current will be controlled to be constant according to the notch. Furthermore, when the speed increases to the field weakening limit shown in c, the output of the armature voltage constant control section EF becomes low in the field current control system, and the armature voltage remains controlled constant. In the child current control system, the output of the field rate limiting section FA is low, and the system has a series winding characteristic in which the field current and armature current are proportional.

In this region c, the notch and the armature current, and therefore the torque, no longer correspond. The relationship between the field current 1F and the armature current FrtIA in parts a to c above is as shown in Figure 4 due to the effect of low order priority, and the armature current changes from 100% field a to a predetermined minimum value. It varies in the range of weak electromagnetic C.

That is, under the same notch condition, the speed V and the field current 1
The relationship between F and armature current 1A is as shown in Figure 7. When the speed exceeds V1, the field enters the field weakening transition region b, and first the field current 1F decreases, but the armature current 1A remains constant. be.
Then, when the speed exceeds V2 and enters region c, IF/A reaches its limit (minimum field weakening rate), and the field current that defines the relationship between (field current F) vs. (upper limit of armature current 1A) The output of the armature current command section FA is the speed deviation vs. armature current command section N.
This becomes lower than the output of A, and this is output as an armature current command, and the armature current 1A also decreases. Therefore, for each region A, b, and c, the following equations are obtained, and the characteristics are as shown in FIG. 4.

In addition, in Fig. 4, field current IF vs. armature current IA
In the relationship, the slope of the characteristic c of the minimum field weakening rate is greater than the characteristic a of the 100% field rate (at full capacity), so the output of the field current vs. armature current command section FA is the speed deviation vs. armature It is thought that it will never be lower than the output of the current command unit NA.

However, in actual operation, as mentioned above, the armature current IA is constant in region b. Only the field current IF decreases.
The field current versus armature current command section FA's low output priority is not given. Then, when entering region c, field current IF decreases and armature current IA also decreases. This means that if low priority is not used, the armature current IA at the same notch
In contrast to trying to make it one pair. In reality, the armature current IA is lowered on the straight line c, indicating that low order priority is at work. The reason why such a low priority is used is that the output of the speed deviation vs. armature current command section NA is constant regardless of the decrease in the field current IF when the speed deviation is constant, that is, when the speed deviation is ΔV-constant. This is because the output of the field current vs. armature current command section FA decreases as the field current IF decreases, and becomes lower than the output of the speed deviation vs. armature current command section NA at the time it enters region c. be.

On the other hand, the relationship between the armature voltage EA and the field current IF is shown in Fig. 5, where the thick straight line where EA is semi-constant is when armature voltage EA is controlled (because the control gain is finite, EA
is not completely constant but slopes).

Also, if we draw the characteristics of the notch versus field current IF, armature current IA, and torque T in the a-c section, we get the result as shown in Fig. 6.
The characteristic of torque T is a function of the square of the notch.

In other words, direct winding tokuju is obtained. In this embodiment, a complicated coefficient multiplier is unnecessary and the circuit configuration is simple. Also, as is clear from Figure 4. The armature current is controlled within the range from 100% field rate to the required minimum weakening rate, so even if overspeed occurs. There is no possibility of deterioration of rectification or flashover due to a decrease in field rate. As explained above, according to the present invention, 100
A DC motor control device that operates stably from the % field region to the field weakening region can be obtained.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional DC motor control device, Figure 2
The figure is a block diagram of a DC motor control device showing one embodiment of the present invention, and FIGS. 3 to 3 are explanatory diagrams of the operation of the present invention. Vp...speed command, VT...vehicle speed, A...armature of DC motor, F...
Same field, Ath... Armature control thyristor, F
th...Field control thyristor, NA...
・Speed deviation versus armature current command section. FA... Field current vs. armature current command section. AL...Low priority section, NF...Speed deviation versus field current command section, EF
...Armature voltage versus field current command section, FL...
...Low priority section.

Claims (1)

[Claims] 1 An armature current control system that controls the armature current of a DC motor based on the deviation between the commanded speed and the actual speed, and a field current control system that controls the field current of the DC motor based on the deviation between the commanded speed and the actual speed. The armature current control system includes a speed deviation vs. armature current command section that generates an armature current command from the speed deviation, and a predetermined minimum field rate according to the field current. Out of the command values from the field current vs. armature current command section that creates the armature current command, the speed deviation vs. armature current command section, and the field current vs. armature current command section, the lower command value is given priority to the electric motor. The field current control system includes a speed deviation versus field current command section that generates a field current command from the speed deviation, and a low priority section that outputs a slave current command as a slave current command. The armature voltage vs. field current command section that generates a field current command for controlling A direct current motor control device comprising: a low priority section that prioritizes and outputs as a field current command.