JPS5826587A - Control device of dc elevator - Google Patents

Abstract

PURPOSE:To improve the power factor reducing the ripple contents of output current by a method wherein a DC motor is provided with the output of power converter making use of the all wave rectifying bridge circuit including a rectifier controlling phase angles subject to chopping by means of a switching device. CONSTITUTION:The comparator PA outputs the voltage command signals Sv comparing the armature current control command Sc corresponding to the speed deviation signals output from the function generator Fm with the armature current. The function generator Fm provides the gate pulse generating circuit PS with the phase command signal Salpha minimizing the control delay angle alpha within the range where the voltage comand signal Sv is larger. The function generating circuit Fp provides the gate pulse generating circuit PP with the pulse width command signal Sp maximizing the pulse width within the range where the voltage command signal Sv is larger and minimizing and specifying the pulse width within the range where said signal Sv is smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a DC elevator, and particularly to a control device for a DC elevator that uses a full-wave bridge to obtain a DC output from an AC power source to control the armature current of a DC motor. Regarding. 1 shows an elevator control system which obtains a variable DC voltage from a three-phase AC power supply and applies it to the armature of a DC motor. The three-phase voltages U, V, and W from the three-phase AC power supply E are connected to six circuits/l'U, , U, , V, , V2. W,
, W, the output voltage EL of the three-phase full-wave thyristor bridge when applied to the AC terminal of the three-phase full-wave thyristor bridge is controlled by controlling the phase of generating the gate pulse of each thyristor, By rotating the sheave S, the counterweight CW is attached via the rope R.
The voltage is applied to the armature M of the DC motor that drives the cage C suspended in the shape of a crane.

The phase that generates the gate pulse (thyristor U.

can be expressed as a delay in electrical angle from the point in time when the voltages of the U and W phases switch to positive, and this is hereinafter referred to as a control delay angle. ) is α, the DC output voltage EL is expressed as: However, when the control delay angle α is zero, the DC output voltage E
The relationships among the output voltage waveform, U-phase voltage waveform, and U-phase current waveform when L is maximum and when α = 90° and DC output voltage EL is zero are shown in Figure 2 (a) and (b). Show/become.

Figure 2(a) shows that, assuming that the time constant of the armature M of the DC motor is sufficiently longer than the period of the power supply, the DC voltage of the load E
o1 In other words, this is a waveform assuming that the back electromotive force of the DC motor is slightly lower than the output voltage EL, and U and V.

W is the phase voltage, EL is the output voltage, and Ul is the U-phase current.

When the output voltage EL is maximum, the center value of the U-phase current U1 matches the center value (maximum value) of the U-phase voltage U, and the phase of the fundamental wave component of the U-phase current U is equal to the U-phase voltage U. The power factor is the highest for this type of control method.

However, as shown in FIG. 2(b), when the output voltage EL is zero, the center of the U-phase current U is at the zero point of the U-phase voltage U, and the fundamental wave of the U-phase current U is The component is delayed by 90° from the U-phase voltage U, and can be said to have a power factor of zero. As described above, the method of controlling the output voltage Et by controlling the firing angle of the three-phase full-wave thyristor bridge has the drawback that the power factor deteriorates particularly in a range where the output voltage EL is low.

Furthermore, the output voltage EL of the three-phase full-wave bridge circuit includes a ripple component whose fundamental wave is six times the power supply frequency, but this ripple component is equal to the output voltage E
The higher t is, the lower it is, and it is maximum when the output voltage Et is zero, and as can be seen from the pulsations of the U-phase current U in FIGS. 2(a) and (b), when the output voltage Et is low, The ripple component of the output current increases. Therefore, when the average values of the output currents are equal, the lower the output voltage Et, the greater the electromagnetic noise of the DC motor tends to be.

Recently, as an armature current control method for DC transmissions that improves these drawbacks, "Apulsewidth Controlled A" has been proposed.
C-tu-DCConverter to Inpro
ve power pactor and wavefo
rm of ACLine CurrentJ titled “IEEE TRANSACTIONS ON IN
DUST'RY APPLICATION, VOL, IA
-15, A6゜NOVEMBER/DECEMBER,
1979 JK proposed. This method is based on the full-wave pleats shown in Fig. 1, and the thyristor U on the positive side of the dicircuit.
In this system, V, , W are replaced with elements having a current cutoff function, and the above elements are subjected to a chopping operation at a predetermined cycle, and the output voltage is controlled by varying the chopping pulse width. According to this method, the AC voltage and current are in phase, so the power factor can be brought close to 1. Further, the DC output voltage hardly includes the sixth harmonic component of the power supply, and the ripple component of the output current can also be suppressed to a small level.

However, in order to continuously control the output voltage down to a small value using this method, it is necessary to narrow the chipping pulse width of the element, but such control is difficult and has limitations. Current transistors or GTOs (gate turn-off thyristors) cannot control the output voltage to about 1/10 of the rated voltage or less. Therefore, a high-speed elevator driven by a DC motor is
Since it is necessary to continuously operate the controller up to a speed of 1/1000 or less of the rated speed, sufficient landing performance cannot be obtained with the above control method.

SUMMARY OF THE INVENTION An object of the present invention is to provide a DC elevator control device that has a good power factor and can reduce ripple components of output current to reduce motor noise.

A feature of the present invention is that nine switching means having a current interrupting function are connected between the output of a full-wave bridge circuit composed of a phase-controllable rectifying means such as a thyristor and the armature of a DC motor as a load. A means for controlling the pulse width for chopping the opening/closing means is provided, and in a range where the output of the conversion device is small, the pulse width is kept constant and the phase angle of the rectifying means is controlled, and in a range where the output is large, The DC elevator is controlled using a high power factor AC-DC converter which controls the pulse width of the opening/closing means by keeping the phase angle constant.

Hereinafter, the present invention will be explained in detail using examples.

First, the operating principle of armature current control of a DC motor driving a DC elevator according to the present invention will be explained using FIGS. 3 to 6.

Here, we will take the case of a three-phase AC power supply as an example and explain the case where GTO is adopted as a controllable switching means that has a current cutoff function, but single-phase AC power or other switching means described below It will be easy to understand when it is used.

FIG. 3 shows an embodiment of the main circuit configuration of the present invention. In the figure, the full-wave bridge is composed of thyristors U, -W, and the three-phase AC power source E is connected to the AC terminal of the full-wave bridge. A gate turn-off thyristor G is installed between armature M.
A chopper circuit consisting of TO, GTO12 is connected.

The above thyristors U1 to W, and GTOl, GTO! The voltage applied to the armature M is controlled by controlling the gate of the armature M. Here, it is assumed that the time constant of the armature M is sufficiently longer than the period of the AC power supply, and that the back electromotive force Et of the armature is a value slightly lower than the output voltage Eo.

FIG. 4 is an explanatory diagram of the operation of FIG. 3, and shows the phase voltages U, V,
W, the waveforms of the output voltage EO and the U-phase current Iu are shown. Here, the phase angle for controlling the gates of thyristors U and ~W2 is expressed as α (Ul), and is expressed as the delay angle from the point when the U-W phase voltage is reversed from negative to positive, and hereinafter referred to as the control delay angle. ), GTO, with period T and pulse width P, QTo
, is chopped with a pulse width of T-P.

Figure 4(b) shows the GTOI when the control delay angle α=0°.
, GTOt are chopped.

In this case, for example, as shown by loop ■ in Figure 3,
When GTO, is fired, thyristor U,.

V! A current flows through the power source E, and a load current flows through the power source E. Next, when GTO, is cut off and QTo, ゛ is fired,
The load current It flows through the loop ■ and does not pass through the power supply E. At this time, the output voltage Eo becomes zero. therefore,
The voltage waveform of the output voltage Eo is a pulse-like waveform determined by the pulse width P, as shown in FIG. 4(b). Therefore, by making the pulse width P variable, the output and voltage E
The O, and 0+ phase currents IU can be controlled.

In this case, the phase delay of the phase current with respect to the output voltage Eo is extremely small, and the power factor can be brought close to 1.

However, there is a limit to narrowing this pulse width P, and it is difficult to control the output voltage EO to below the rated value of about 1710.

Therefore, in the present invention, the output voltage Eo is continuously controlled to zero by controlling the control delay angle α while keeping the pulse width P at its shortest.

FIG. 4(C) shows the state in which the pulse width P is kept at the shortest.
This is a waveform when the control delay angle α=approximately 90°, that is, the output voltage is near zero. That is, the thyristors U, ~W in Fig. 3 are fired at a control delay angle of 90°, and the GT
Ol is chopped with a pulse width P during the conduction period determined by the control delay angle of 90°. Therefore, as shown in the figure, the reactive power can be made sufficiently small, and the power factor in the low output range can be improved.

The relationship between the phase angle and the .zeta. pulse width with respect to the output voltage described above is shown in FIG. The figure shows the relationship between the pulse width Sp and the phase angle Sa with respect to the voltage command Sv. The voltage command Sv on the horizontal axis is the ratio to the rated voltage, and the pulse width P and phase angle α on the vertical axis are the ratio to the total conduction width, respectively.
It is expressed as a control delay angle. As can be seen from the figure, the pulse width Sp is made variable up to 0.1 of the rated voltage, and the phase angle sa is made variable below 0.1 of the rated voltage to control the voltage down to zero.

Various methods can be considered to obtain the pulse width P and phase angle α according to the voltage command Sv.
As shown in the figure. This FIG. 6 shows a function generator Fiy with the characteristics shown.
and Fp. These Sp and S are respectively a pulse width command and a phase angle command, and G
By gate-controlling TO, , GTO2 and thyristors U1 to w2, voltage control according to voltage command Sv becomes possible.

That is, when the pulse width P is kept constant at 0.1 and the control delay angle α is changed from 90' to 00, the output voltage becomes 0 to 031XY1ζE. Continuing π When controlling a negative output voltage, α is set to 90'.

A specific embodiment of the DC motor control of the present invention based on the operating principle described above is shown in FIG. 7 below.

This will be explained using FIG.

FIG. 7 is an overall configuration 10 of the power converter according to the present invention, and FIG. 8 is an explanatory diagram of its operation.

Next, the details will be explained. In the figure, PS is a gate pulse generation circuit of a thyristor, and a three-phase power supply E is connected to a transformer T.
Line voltage UW, VU, WV17Cf with neutral point at 2
Switch L, 3-phase phase shift iPU, PV.

Entering PW. The phase shifters PU, PV, and PWK also receive a phase command signal Sa. The phase command signal Sa is generated by a function generator F having an output (characteristics in FIG. 6) such that the control delay angle α becomes 0 in a range where the voltage command signal Sv is large, that is, a range where the output voltage is large. Hence the phase shifters PU, PV.

PW generates wide pulses as shown in FIG. 8(a) that are compatible with the phase command signal sa, and applies these pulses to the gates of thyristors U, ~W. Here, phase shifter PU
, PV, from pin number 1 of PW, the positive half wave of the power supply E,
Pin number 2 generates a gate pulse that controls the negative half wave of power supply E1.

A pulse width command signal Sp is input to the GTO gate pulse generation circuit PP. This GTo pulse width command signal Sp is a signal in which the pulse width is small and constant in the range where the voltage command signal Sv is small, that is, in the range where the output voltage is small, and in the range where the voltage command signal Sv is large, that is, in the range where the output voltage is large. Signal with increasing pulse width (Characteristics in Figure 6)
is obtained by a function generator Fp that generates .

Therefore, the gate pulse generation circuit PP of the GTO generates pulses GT, . . . GT with pulse widths P, .

are generated and applied to the gates of GTO, , GTO,.

These pulses cause the period of P to be GTO.

is conductive, GTO is non-conductive, and GTO is in the P2 period.

Non-conduction, GT02tl - conduction control.

FIG. 9 shows an embodiment of a circuit for controlling a current elevator using the above-described circuit system according to the present invention.

In the figure, a comparator PC compares the speed command and the output of a speed generator PG connected to a DC motor, and the function generator Fffl uses the output to obtain an armature current control command Se.
Enter.

This armature current control command Se and the output of the DC current transformer CT that detects the armature current are compared by a comparator PA, and the deviation is calculated by the phase angle control function generator Frs, which is a pulse width control function generator. FPK is input, and the control delay angles and G'T of thyristors U and -W are input through the thyristor gate pulse generation circuit PS and the GTO pulse width generation circuit PP.
O,,GTO.

The armature current is unidirectionally controlled by controlling the pulse width of the current.

On the other hand, the deviation between the speed command and the output of the speed generator is input to a function generator Ft for obtaining a field current control command St'Fe-.

In accordance with this field current control command St, the field current control phase shifter FPS and push-pull thyristor amplifier th control the current flowing through the field winding F in both positive and negative directions.

The armature current and field current are controlled by function generators Fffi and Ft so that the armature reaches its rated value when relatively large torque is not required, such as when the elevator is running at a constant speed. The field current is controlled at a constant value, and the magnitude and polarity of the field current are varied. Also, when large torque is required, such as during acceleration and deceleration, the field current is kept constant and the armature current is increased above the rated value. It is controlled so that the

This type of control system has the feature that the armature current is unidirectional and four-quadrant operation of forward/reverse, forward/reverse, and regenerative operation is possible.

As described above, according to this embodiment, the power factor of three-phase AC power conversion and inverse conversion is improved, and the capacity of the power supply can be reduced.

In addition, in the conventional embodiment shown in Fig. 1, in order to eliminate the drawback that when a power outage occurs in a regenerative state, the output voltage of the thyristor circuit becomes zero, the armature current increases rapidly, and the thyristor is destroyed. Normally, it is necessary to insert a DC contactor. However, in this embodiment, a chopper circuit consisting of GTOs and GTO2 is connected between the DC terminal of the full-wave bridge and the motor, so that when the armature current exceeds a certain level, the GTOs and GTO2 are turned off. By applying an off-pulse gate signal, it is possible to cut off the armature current. Therefore, a DC contactor is not required, and the device can be made smaller and the cost can be reduced.

In the above embodiment, a case was explained in which a three-phase to DC converter was used as the power converter, but the present invention can be applied even if the elevator is controlled using power conversion with other multi-phase AC or single-phase AC. Of course, it can be applied.

FIG. 10 shows an example of power conversion between single-phase alternating current and direct current, and FIG. 11 shows its operating waveform.
, as shown in FIG. 10, the thyristors R, r-"S.

A chopper circuit consisting of G T O+ and G T Ot is connected between the DC terminal of the full-wave bridge circuit consisting of G T O+ and G T Ot.

This thyristor R5-8. Figure 11(a) shows the output voltage Eo when only the phase angle α is controlled.
In addition, the output voltage Eo when GTOR, GTO8, is opened and closed with a pulse width P is shown in the same figure (b). This diagram is
This is a case where the control delay and the angle α are set to 90' and the output voltage Eo is set to zero.As in the previous embodiment, if the pulse width P is minimized, the power factor when the output voltage Eo is set to zero can be dramatically reduced. It can be improved. Similarly, the delay angle α is set to θ~18
By controlling the pulse width P to 0° and controlling the pulse width P from the maximum to the minimum, it is possible to control the entire range from forward conversion to inverse conversion.

In the above embodiments, the fundamental wave power factor can be improved, but
As shown in FIG. 4, harmonics are generated because an intermittent current flows through the AC power source.

These harmonics can be reduced by inserting a filter circuit between the full-wave bridge and the chopper circuit. An example thereof is shown in FIG. 12, and an operation waveform diagram is shown in FIG. 13.

In the diagram, i and Lo are the accelerator, and CD is the capacitor.
These constitute a filter circuit, and the current IL flowing through the LD
If D is selected to be a continuous constant, the output voltage Eo of the full-wave bridge when the control delay angle α of the thyristors U, -W2 is set to 0 has a waveform as shown in FIG.

Then, while maintaining the control delay angle α=O, GTO is set to pulse width P and GTOt is set to T-P as in the above embodiment.
Terminal voltage EL of capacitor CD when opening/closing is controlled as shown in Fig. 13(g) with a pulse width of The result will be as shown in Figures (C) to (0).

By doing this, not only can the power supply current waveform be improved, but since the output current ILD of the full-wave bridge is continuous, the gate pulses of the thyristors U1 to W can be fired even with narrow width pulses, which simplifies the control circuit. It also has the effect of becoming.

As described above, according to the present invention, it is possible to perform power conversion with a good power factor over a wide range in controlling a DC elevator, and the ripple component of the output current is also reduced, thereby making it possible to reduce motor noise.

[Brief explanation of the drawing]

Fig. 1 is a main circuit diagram of a general three-phase to DC converter, Fig. 2 is a waveform diagram in a conventional three-phase to DC converter, Fig. 3 is a main circuit diagram of an embodiment of the present invention, and Fig. 4 is a main circuit diagram of a conventional three-phase to DC converter. Figure 3 is a waveform diagram for explaining the operation of the circuit, Figure 5 is a characteristic diagram of pulse width and phase angle with respect to voltage command, Figure 6 is a function generation circuit diagram to obtain the characteristics shown in Figure 5, and Figure 7 is a circuit diagram when controlling the armature current of a DC motor using the present invention, FIG. 8 is a waveform diagram for explaining the operation of FIG. 7, and FIG. FIG. 10 is a diagram of another embodiment of the main circuit of the present invention, FIG. 11 is an operation waveform diagram of FIG. 10, and FIG. 12 is a main circuit diagram of another embodiment of the present invention. 13th
The figure is an operation waveform diagram of FIG. 12. E,...3-phase AC power supply, U, V, W...3-phase voltage,
GTo,, GTO,...Kate turn-off thyristor, U+, 'Vb, Wt, Us, L
, Wt "'-thyristor, α... control delay angle, P
... Opening/closing time width, PS, PP... Gate pulse generation circuit, Fa, FP... Function generator, LD... Reactor, CD... Capacitor, M... DC motor armature, S ... Sheave, C ... Cage, T, ... Transformer, PA, PC ... Comparator, th ... Push-pull thyristor amplifier, CT ... DC current transformer, PG ...
speed generator. Agent Patent Attorney Akio Takahashi -'-1- 2,1: \, ~ / #+rsn? 710 wins 115fJ ζ4) No. 121!1

Claims (1)

[Scope of Claims] 1. In a control device for a DC elevator that is driven and operated by a DC motor and runs on multiple floors, power between AC and DC using a full-wave bridge circuit including a rectifier that can control the phase angle. switching means for chopping the converter output, means for controlling the phase angle of the rectifying means in accordance with a desired output voltage of the converter, and controlling the pulse width for chopping the switching means; What is claimed is: 1. A control device for a DC elevator, comprising: means for controlling a DC elevator; 2. In claim 1, the power conversion device changes the phase angle when the desired output voltage is below a predetermined value, and changes the pulse width when the desired output voltage is above a desired value. 1. A control device for a DC upper 4-lever, characterized by the following configuration: 3. In claim 2, the phase angle variable means changes the phase angle according to the desired voltage when the desired voltage is below a predetermined value, and changes the phase angle according to the desired voltage when the desired voltage is above a predetermined value. A control device for a DC elevator, characterized in that it is configured to maintain a phase angle to a minimum (in the case of a control delay angle). 4. In claim 2, the pulse width variable means maintains the pulse width at a minimum when the desired voltage is below a predetermined value, and adjusts the pulse width according to the desired voltage when the desired voltage is above a predetermined value. 1. A control device for a DC elevator, characterized in that the control device is configured to change the pulse width by changing the pulse width.