JPH07118934B2 - DC motor field controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a DC motor drive control device that performs speed control using both electric motor armature voltage control and electric motor field current control, and more particularly to a base rotation speed of the DC motor. The above description relates to a field controller for a DC motor that performs power constant control for keeping the motor armature voltage constant.

[Conventional technology]

As the DC motor driving device for controlling the speed of the DC motor, the one shown in FIG. 3 is commonly used.

FIG. 3 shows the configuration of the main part of a conventional DC motor drive device, where 1 is a speed setter, 2 and 2'are comparators, 3 is an armature control circuit, 4 is a DC motor, and 5 is speed detection. , 6 is a field current setting device, 7 is a field current detector, and 8 is a field control amplifier.

The structure of such a connection structure is as follows.

That is, in response to a speed command from the speed setter 1, DC power is applied to the armature of the DC motor 4 via an automatic speed stabilizing circuit (not shown) in the armature control circuit 3 and the DC motor 4 rotates. To do. It is assumed that a field current preset by the field current setting device 6 is supplied from the field control amplifier 8 to the field of the DC motor 4.

Then, when the DC motor 4 starts to rotate, the speed detector 5 connected to the DC motor 4 generates an output, and the comparator 2 calculates the speed setting signal S ₁ and the speed feedback signal S ₅ to obtain the final output. Then, the DC motor 4 is operated by the speed command from the speed setting signal S 1 from the speed setter ₁ .

Here, the speed setter 1 is adjusted to control the increase of the voltage of the motor armature accompanying the increase of the speed command in order to drive the DC motor 4 in the region above the base rotation speed, that is, in the power constant region. It is well known that it is necessary to perform constant motor armature voltage control by means of a motor.

As a general implementation means therefor, as illustrated, comparator field current setter 6 outputs at 2 ', the operation of the field current detector 7 output and the armature voltage signal S ₃ is made, field control amplifier 8 Generates a field current output S ₈ so as to weaken the field current when a predetermined armature voltage is reached, so that the armature voltage is kept constant.

[Problems to be solved by the invention]

On the other hand, in such a connection configuration, it is necessary to make the control response time of the armature drive system of the DC motor faster than the control response of the field control system of the DC motor in terms of the control stability of the entire system. Is well known from

However, in such a control system, when the electric motor is driven in the state where the speed command is suddenly changed or the speed setting is set to the maximum, there are the following problems due to the difference in the control response time. . That is, referring to the waveform diagram of each part of the apparatus shown in FIG. 3, when the speed setting signal S ₁ suddenly increases at the time point T ₁ as illustrated, the transition from the time point T ₁ to the time point T ₂ and as shown from time T ₂ to the waveforms of the transition, the armature voltage signal S ₃ and the field current output S ₈ because of control delay of the motor field current, the field with cause large overshoot the motor armature voltage Since the magnetism weakens, the number of revolutions of the DC motor rises above the maximum speed setting, resulting in a very dangerous state.

As a measure to prevent the occurrence of such an abnormal state, a field loss detector (not shown) is attached to the output of the field control amplifier 8 according to the field loss detection level I _pu as shown in the figure, so that the field current output S ₈ A protection method for stopping the DC motor by detecting an abnormal decrease or loss of the DC motor has been proposed.

However, field attenuation characteristics of current are those determined by the磁定number of field磁自body one to the motor, thus for but varies widely by an electric motor capacity, etc., its field loss detection level I _pu settings It was annoying.

[Means for solving problems]

The present invention has been made in view of the above points, and provides an apparatus having the following connection configuration.

That is, in particular, what is arranged as a main constituent part is that in the field control amplifier part, a minimum field current control amplifier part is separately arranged in addition to a general field control amplifier, and a priority circuit for the output of both control amplifiers. Is formed and output is supplied. Further, the field loss detection level is obtained in response to the setting of the minimum field current control amplifier.

[Action]

Therefore, the present invention, by using the solution as described above, not only the stable operation of the DC motor but also the sudden change of the speed command and the driving of the DC motor at the maximum speed setting,
It is possible to realize smooth control without abnormally reducing the field current.

〔Example〕

FIG. 1 shows a main structure of an embodiment of the present invention.
Reference numeral 2 "is a comparator, 9 is a field control amplifier unit, 10 is a minimum field current setting unit, and 11 is a field loss detector. In the figure, those having the same reference numerals as those in FIG. 3 have the same function. .here,
The field control amplifier unit 9 is composed of field control amplifiers 91 and 92 and a priority circuit 93.

FIG. 2 is a waveform diagram of each part of the device shown in FIG. 1, which is similar to FIG. 4, where S ₃ ′ is an armature voltage signal, S ₈ ′ is a field current output, and S ₉₁ and S ₉₂ are The field control output, I _MN, is the minimum field current level.

Next, the function of the connection configuration shown in FIG. 1 will be described in detail with reference to FIG.

That is, in FIG. 1, the comparator 2 'field current setter 6 output, the field current detector 7 output and the armature voltage signal S _3' at its field control device that obtain and the comparator 2 " A field control amplifier 91 having an output as an input is arranged in the same manner as in the conventional case. Therefore, as shown in the figure, the comparator 2 ″ inputs the minimum magnetic field current setting device 10 output and the field current detector 7 output. Then, the calculated output is given to the field control amplifier 92. Moreover, the priority circuit 93 has control outputs 91, 9
2 is obtained and the larger level of both is generated as the field current output S ₈ ′. Further, a field loss detector 11 connected to the output of the comparator 2 ″ is arranged.

In such connection structure of nuclear, the speed set by now time T ₁ signal S DC motor 4 as a change in the speed command shown in ₁ is about to be driven, the motor armature voltage is an internal armature control circuit 3 As shown in the armature voltage signal S ₃ ′, it rises with the determined control time,
The specified voltage value is reached at time T ₂ ′.

Accordingly, 'to be about to enter the power constant region at this point in time T _2' time T ₂ field control output S ₉₁ as illustrated more gradually reduced holding power constant characteristics are weakened This field current but not to try and control the response time of the field control amplifier portion 9 as described above is longer than the control response time of the speed loop in the main control system, overshoots the armature voltage signal S ₃ 'is generated. On the other hand, since the field control output S ₉₁ continues to decrease, at the time T ₂ ″ at which the field current output S ₈ ′ reaches the minimum field current level I _MN as illustrated, the output signal of the comparator 2 ″ is output. The input field control amplifier 92 and the priority circuit 93 are effective. That is, after time T ₂ ″, the field control output S
₉₂ becomes effective, so that the priority circuit 93 can realize the state represented by the field current output S ₈ ′ as shown in the figure. Therefore, as shown in the armature voltage signal S ₃ ′, although the motor armature voltage has some overshoot that occurs during the decrease of the field current, it is possible to perform the preferable power constant control of the motor. .

Also, as a protection method against field loss, the minimum field current setting device
10 and the comparator 2 ″ are effective, and the comparator 2 ″
The loss-of-field detector 11 arranged on the output side detects the loss-of-field detection by providing a gain difference between the field-control amplification 92 and the loss-of-field detector 11 with respect to the calculation result of the comparator 2 ″. It is clear that the level I _pu can be easily responded to.

〔The invention's effect〕

As described above, according to the present invention, optimum power constant control can be performed by adding a simple minimum field current setting portion, and set field loss detection that does not require fine adjustment can be performed. It is possible to provide a device that realizes a useful and optimum DC motor control system.

[Brief description of drawings]

FIG. 1 and FIG. 2 are system diagrams showing a main part configuration of an embodiment of the present invention and diagrams showing waveforms of respective parts, and FIGS. 3 and 4 show a main part configuration of a conventional DC motor drive device. It is a figure shown and a figure showing each section waveform. 1 ... Speed setter, 2, 2 ', 2 "... Comparator, 3 ... Armature control circuit, 5 ... Speed detector, 6 ... Field current setter, 7 ... Field current detection Container, 9 ... Field control amplifier,
10 …… Minimum field current setting device, 11 …… Field loss detector,
S ₈ , S ₈ ′ …… Field current output, S ₉₁ , S ₉₂ …… Field control output,
I _MN ...... Minimum field current level.

Claims (1)

[Claims] 1. An armature control circuit for controlling a motor armature voltage by comparing a speed setting signal and a speed feedback signal, and obtaining a comparative output of a field current setting signal and a field current feedback signal in a power constant region. A direct current motor drive circuit comprising at least a field control circuit for controlling a motor field current, a first field current control amplifier having the comparison output as an input, a minimum field current setting signal and the field current feedback signal. Of the second field current control amplifier and the loss of field detector for obtaining an output signal comparing with the above, and the output value of the first field current control amplifier is lower than the output value of the second field current control amplifier. A field control device for a DC motor, wherein the field control device further comprises a priority circuit for generating the second field current control amplifier output.