JPS58151875A - Changeover method for load current of antiparallel connection power rectifier - Google Patents

Abstract

PURPOSE:To shorten the changeover time of the power rectifier by changing over the power rectifier by detecting load current value just before ignition and setting a first firing angle after changeover while being subtracted only by predetermined value. CONSTITUTION:When load currents reach 0, output signals S12 from a comparator 21 reach an L level, and the state of interruption of currents is detected. When a FF2 is supplied with pulses P2 through an AND gate 23 after ignition, output signals S3 from an exclusive NOR27 reach an H level, and a one-shot multivibrator 28 supplies a firing-angle arithmetical section 13 and a rate control section 14 with pulses P3. The firing-angle arithmetical section 13 takes in deviation signals (240 deg.-alpha) supplied from a deviation detecting point, and supplies a gate pulse generating section 15 with signals indicating the firing angle (240 deg.- alpha) through the rate control section 14. Where alpha represents a firing angle indicated by output signals S4 from the rate control section 14.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention uses forward converters connected in anti-parallel to
The present invention relates to a load current switching method suitable for use when driving a 1g-machine.

Driving a DC motor using forward converters connected in reverse parallel
A typical circuit example for this case is shown in FIG.

In this figure, reference numerals 1 and 2 denote forward converters each composed of a thyristor, which are connected in antiparallel to the armature 3 of the DC motor. Further, a three-phase alternating current power supply AC is supplied to each of the forward converters 1.2. 4 is a field winding;
It is connected to a variable DC power supply 5.

By the way, as is well known, the rotational speed of a DC motor is controlled by controlling the armature current (hereinafter referred to as load current), and the direction of rotation is reversed by reversing the direction of the load current.

In the circuit shown in Fig. 1, when controlling the load current, a firing angle signal corresponding to the load current command value is supplied to forward converter 1 or 2, and when switching the direction of the load current, the firing angle signal is supplied to forward converter 1 or 2. For example, switch the forward converter to
If the forward converter 1 is in an operating state when the DC motor is rotating in the forward direction, when the DC motor is rotating in the reverse direction, the forward converter 1 is in an inoperative state and the rear converter 2 is in an operating state.

Conventionally, the following two methods have been used to switch the load current direction.

■ First, in order to stop the operation of the forward rotation a converter,
The firing angle supplied to this forward converter is maximized and the load current is guided to O. Since the load current does not reach O immediately due to the inductance component of the armature, the charge current C* is After the ignition angle signal reaches 0), the firing angle signal supplied to the forward converter for forward rotation is cut off. Then, a reverse conversion forward conversion atc firing signal is supplied to reverse the direction of the load current.

■ It is almost the same as method (■) above, but after increasing the firing angle of the forward rotation xi converter to the maximum, the average value of the load current is detected, and when this value becomes 0, the reverse rotation order is set. Provides a firing angle signal to the transducer.

However, in methods (1) and (2) described above, it takes a long time to switch the direction of the load current, and in order to maximize the firing angle at the time of switching, it is difficult to return the firing angle to the desired value after switching. However, it is well known that when controlling the firing angle of the forward converter in the decreasing direction during operation, it cannot be rapidly decreased (generally by a maximum of about 30 degrees).

In view of the above, the conventional method also has the following drawbacks.

When controlling the rotational speed of a DC motor driven under a light load condition to a constant speed, the command value of the load current fluctuates around 0, and the polarity is repeatedly reversed.In this case, in the conventional method described above, the forward conversion The switching time and firing angle recovery time after switching were long, and the ability to follow polarity reversal of the load current command value was poor, resulting in extremely poor constant speed control characteristics.

The present invention has been developed in consideration of the above-mentioned circumstances.The switching time of the forward converter and the firing angle recovery time after switching are extremely short, and the constant speed control characteristics of the DC motor under light load are extremely good. This method provides a method for switching the load current of a converter, which detects whether the load current value immediately before ignition is 0 or not, and if it is 0, switches the forward converter, and changes the initial ignition angle after switching. In this method, the firing angle is set by subtracting the firing angle immediately before switching from a predetermined value.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention. In this figure, parts corresponding to those in the $1 figure are designated by the same reference numerals, and their explanation will be omitted.

In this figure, S is a current value command signal, which is a signal supplied from another circuit not shown. This current value command signal S is supplied to the command signal converter 10 and also to the comparator 22. be done. The command signal converter 10 outputs the absolute value of the current value command signal S, and its output signal 5tr=Isi) is supplied to the deviation detection point 11. Further, the command signal converter 10 includes an exclusive NOR circuit 27
When the signal S supplied from 8. reaches 1L level, its output signal 8. The output signal SII of the load current detector 20 is supplied as a subtraction signal to the reference deviation detection point 11, which is configured to set 0 to 0. This load current detector 20 has variable fi
The signal S1° corresponding to the load current Is detected by the ficT is converted into a value equal to the load current Is and output. Amplification@1212 deviation detected by deviation 1 (
8*8tt) and supplies it to the firing angle calculation unit 13. The 0 firing angle calculation unit 13 calculates firing angles of forward conversion @1 and 2 based on the supplied signal, and the deviation (L -8
Calculate the firing angle so that n) becomes 0. The output signal of the firing angle calculation section 13 is supplied to the rate control section 14. The rate control section 14 is the firing angle calculation section 1
When the output signal of 3 is a signal that decreases the firing angle, if the decrease width is greater than a predetermined value (generally 30 degrees 1 degree), the decrease width at this time is divided into 0. If the output signal of the angle calculating section 13 is a decrease of 60 degrees from the previous firing angle, a firing angle signal with a reduction width of 30 degrees is divided vertically into two and outputted. In addition, when the output signal of the firing angle calculation unit 13 is a signal that increases the firing angle, and when the output signal is a signal that decreases the firing angle but the amount of decrease is small, the rate control unit 14 calculates the firing angle. The output signal of section 13 is output as is. The output signal S4 of the rate control section 14 is supplied to the gate pulse generation section 15, and
It is supplied to the deviation detection point 25 as a subtraction signal.

Here, other functions of the firing angle calculation section 13 and rate control section 14 described above will be explained. A firing angle signal of 240° is supplied as an addition signal to the deviation detection point 25, and the deviation from the output signal S4 of the rate control section 14 is detected here. If the signal S indicates the firing angle α1, the deviation at the deviation detection point 25 is (2
40'-α, ), and this deviation signal is supplied to the firing angle calculation unit 13 via the amplifier 26.
The firing angle calculation unit 13 receives the pulse P from the one-shot multi 28.
1 is supplied, it takes in the deviation signal (240'-a, ) and the signal corresponding to this signal, i.e., the firing angle (
240°-α,) is supplied to the rate control unit 14. Also, when the rate control unit 14 is supplied with the one-shot multi 28 or the Lahalus P,
The signal supplied from the firing angle calculation section 13 is directly supplied to the ogate pulse generation section 15. In this case, firing angle calculation l
Even if the output signal of l1ia significantly reduces the firing angle, it does not suppress the reduction.

Next, 15 is a gate pulse generation section. This gate pulse generator 15 generates a set of three pulses, ie, a gate pulse α1, a pre-ignition pulse P1, and a post-ignition pulse P, based on the output signal 84 (a signal instructing the firing angle) of the rate control unit 14. It is something to do. Here, FIG. 3 (C) shows the generation timing of the gate pulse GP#A pre-arc pulse P1 and post-ignition pulse Pt. The gate pulse Gde is a pulse for firing the forward converters 1 and 2 and
The signal 8 is a pulse corresponding to the indicated firing angle.The post-ignition pulse P, is supplied to the input terminal 23b of the AND gate 23, and the pre-ignition pulse P, is supplied to the DIl flip-flop 1 (hereinafter FFl). The gate pulse GP is supplied to the G input terminal of the ant game)-16.
, 17 input terminal isa.

17m<supplied. The other input terminals 16b and 17b of the AND gates 16 and 17 are connected to the Q output terminal and the Q output terminal of the FF, respectively.
7 is configured so that either one is open. 18
．． 19 are pulse amplifiers that amplify each gate pulse GP to a predetermined level, and each output signal is supplied to the gate of each forward converter 1.2. And gate pulse G
is supplied to the forward converter 1 by the output calyx of the FF through the path of AND gate 16 → pulse amplifier 18, or
Alternatively, it is supplied to the forward converter 2 through the path of AND gate 17 → pulse amplifier 19, while 21 and 22 are comparators, and when the input signal exceeds O,
It outputs a level signal, and when the input signal is 0 or less, it outputs an I level signal. The comparator 21 has a current transformer C.
The output signal S, of T. is supplied to the comparator 22, and the current value command signal 8. is supplied to the comparator 22 as described above. is supplied with the signal S. is a signal with a value equal to the absolute value II·[ of the load electric light weight·. The output signal 811 of the comparator 21 is supplied to the D input terminal of the FF, and the output signal of the PF is supplied to the input terminal 23m of the AND gate 23 as an open/close signal. And the output signal of AND gate “23 is FF,
is supplied to the G input terminal of. The output signal S of the comparator 22
is FF, D input terminal and exclusive Noah 27
The signal is supplied to the input terminal 27 of . The other input terminal 27b of the exclusive NOR 27 is supplied with the Q output signal of the FF. The output signal of the exclusive Noah 27 is supplied to the one-shot multi 28 and also to the command signal converter 10 described above. The one-shot multi 28 outputs one pulse when the input signal, that is, the output signal of the exclusive NOR 27 changes from the L# level to the 0H level.

Further, of the above-described configuration, the portion surrounded by the dashed line in FIG. 2 constitutes the load current switching section 30.

Next, FIG. 2 shows the operation of this embodiment with the above-described configuration.
This will be explained with reference to FIG. 4, taking as an example a case where the polarity of the current value command signal is reversed from positive to negative.

For the sake of brevity, a description of the operation of this embodiment upon power-on will be omitted for the following two reasons.

■ The operation when the power is turned on in this embodiment is electric fif1.
1. The operation is approximately the same as that at the time when the polarity of the command signal S is reversed.

■ When the power is turned on, if the current value command signal 8° is positive, the AND gate 16 opens and the forward converter 1 for forward rotation
is driven, and similarly, if the current value command signal S1 is negative, the AND gate lγ is opened and forward conversion for reverse i)
It can be easily understood from the following operation explanation that the motor 2 is driven. Figure 4 (Xun-Wei) shows that when the motor 3 shown in Figure 2 is driven with a light load, the current FIG. 6 is a diagram showing waveforms of various parts of the circuit when the value command signal S1 is linearly changed from positive to negative.

First, we will explain the operation before the time t when the current value command signal S crosses O. In this case, the AND gate 1
6 is opened, AND gate 17 is closed, and current value command signal 8. Gate pulse GP corresponding to (see figure (C))
is supplied to the forward rotation converter l via the AND gate 16 and the pulse amplifier 18, thereby causing the armature 3 to rotate forward. At this time, the output signals of the comparators 21 and 22 are 8□.

Since each of the input signals S1° and S8 are greater than 0, both S and S are at the °H'' level (see (e) and (Q) in the same figure).If signal 83 is always at the #H level, then the The FFI shown in Figure 2 does not change its state even if the pre-ignition pulse P is supplied, and the ζ output signal is always #L level (see Figure 4 (i)). 23 is in the closed state, and the 1L# level signal continues to be supplied to the G input terminal of the FF.As a result, the state of the FF does not change, and the #H# level signal is output from the ζ output terminal. (See Figure 4 (-)) As a result, both input terminals 27m and 27b of the exclusive NOR 27 always have #H#.
A level signal is supplied, and its output signal S is shown in FIG.
2) Maintain the 1H level as shown in ・Thus,
The one-shot multi 28 does not operate, and the pulse P is not output. Also, since the output signal 88 of the command signal converter 1o is the signal S, which is at the lTH# level, as shown in Figure 4) Current value command signal 8. equal to the absolute value of the current value command signal 8. When becomes O at time t, the output signal S- of the comparator 22 becomes low level. As a result, the output signal S of the exclusive NOR 27 becomes ・L
# level, and the output signal Sl of the command signal converter 10 becomes 0 as shown in FIG. 4 (,l). As a result, from time t onwards, the ignition calculating section 13 calculates the ignition angle such that the load current I- becomes O.

On the other hand, the load current Ia once again becomes 0 between times t and t3. As is well known, this is a phenomenon called a current intermittent state, and when the DC motor is driven under a light load state, if the current value command signal S, is around 0, the load current 1. This is a phenomenon in which the value becomes O before the next ignition time. Also, in this state, the load current immediately before the next ignition will always be 0.
In this embodiment, as will be explained below, the load current intermittent state is detected at time t, and the direction of the load current I- is switched at the next ignition time.

When the load current I- becomes O at time t, comparator 2
The output signal S□ of 1 becomes the 9L# level as shown in FIG. 4(f). As a result, when the pre-ignition pulse P is supplied to the G input terminal of FF at time t, the ζ output signal of FF becomes #H level as shown in FIG. 4 (1), and the current Detect intermittent conditions.

When the output signal of the FF reaches the °H'' level, the AND gate 23 becomes open. Then, when the gate pulse G is issued at time t4, the output state of the FF has not changed at this point. Therefore, the gate pulse G? is supplied to the forward converter 1 for forward rotation via the AND gate 16 and the pulse amplifier 1B.

Then, at time t, when the post-ignition pulse P is supplied to the G input terminal of the FF via the AND gate 23,
Since signal S is already 1L level, 1? F
, the output state of , is inverted, and the ζ output signal becomes - level (see Fig. 4 (2)) - As a result, the input terminals 2γm and 27b of the exclusive NOR 27 are both supplied with the [Lulubell signal]. Therefore, the output signal 8 of the exclusive Noah 27. becomes #H# level, one shot multi 28
is pulse P.

The zero firing angle calculating section 13 supplies the pulse P to the firing angle calculating section 13 and the rate control section 14.

is supplied, it takes in the deviation signal (240'-α,) supplied from the deviation detection point 25 via the amplifier 26, and
A signal instructing the firing angle (240'-αt) is supplied to the gate pulse generator 15 via the rate controller 14. Moreover, since the rate control section 14 is supplied with the pulse P at this time, even if the output signal of the firing angle calculation section 13 significantly reduces the firing angle, the reduction width is not suppressed.

Then, the gate pulse generator 15 generates a deviation signal (240°
-αl) is output at time t.

On the other hand, time 1. From then on, as can be seen from FIGS. 2 and 4, the output state of the FF does not change, so at time 1. In this case, the AND gate 17 is in an open state.

Therefore, the gate pulse GP at time t is the AND gate 17. 11 cost converter 2 via pulse amplifier 19
As a result, the direction of the load current I is switched and the armature 3 rotates in the opposite direction.In this way, in this embodiment, as can be seen from Figure 1114 (a), the polarity of the current value command signal S is reversed. In contrast, a delay of only one firing period results in a load current of 1. Switch the orientation.

On the other hand, when the signal S becomes the #H# level at time t, the output signal S of the command signal converter 10 becomes equal to the absolute value of the current value command signal Sl again. As a result, the firing angle after time t is based on the signal S (see Fig. 4(a)).
) This is the current value command signal S after the load current is switched in this embodiment.

This shows that it has extremely good followability.

The reason why the followability is so slow in this embodiment is that the initial firing angle after switching the load current is set to 240 degrees as described above.
This is because the angle change is set as −α, ).

As can be seen from the above, this embodiment is extremely suitable for switching the direction of the armature current of a DC motor driven with a light load.It should be noted that the pulse amplifier 18 in this embodiment Operations other than 19 and the load current detector 20 may be performed using a microprocessor. An example of a control method in this case is, for example, a method in which the load current 1 is controlled in synchronization with the gate pulse GP. In this method, the firing bale pulse Pl becomes the start signal for the next firing angle control calculation and load current switching. Also, the initial firing angle value after switching (240'-
If αl) is not required, pulse P and deviation detection point 25
becomes unnecessary.

As explained above, according to the present invention, it is detected whether the load current value immediately before ignition is O or not, and when it is 0, the forward converter is switched, and the first ignition angle after switching is detected. Since the setting is made by subtracting the firing angle immediately before switching from a predetermined value, it is possible to extremely shorten the switching time of the forward converter and the firing angle recovery time after switching. , it is possible to significantly improve the control characteristics when controlling the rotational speed of a DC motor at a constant level during light loads.

[Brief explanation of the drawing]

1p11 diagram is antiparallel! A circuit diagram showing an example of a circuit in the case of driving a DC motor using an I-shaped forward converter, FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention, and FIG.
M) to (C) are respectively the gate pulse generator 1 shown in FIG.
5 is a waveform diagram showing the output waveform of the circuit shown in FIG. 30...Load current switching section. Applicant Shinko Denki Co., Ltd. Procedural Amendment (□. 57.723 Showa year Power Japan Patent Office Commissioner 1, = JF display t+nT++ 1957 special plan 1m 82869 No. 2,
Name of the invention Load current switching method for anti-parallel connection forward converter 3, Person making the correction: IJsf #f - Hitokami Tsuna Electric Co., Ltd. 4, Agent: June 29, 1960 (Delivery date) (11 Specification) The result //* Line 11 from the top r(a)~
(g) J and aru k rta)~o+'' is corrected. (2) In the specification, from the top to the bottom of the page, there is a message that says "(see figure (
◎ (3) From the top of page 1 of the specification, please correct ``(see bag reference diagram (j))'' instead of ``(see bag drawing (j))''. The line ``Q output signal'' is corrected to ``t-rQ output signal''. (4) In the 16th line from the top of the compiled page of the specification, the text "r (see Figure 844 (g))" has been corrected to "(See Figure (j))". (5) On page 1g, line d of the specification, “(a) to (g)
'' is corrected to ``tr(a)~(j)''. (Among the 61 drawings, the reference number is corrected as shown in the attached sheet.

Claims (1)

[Claims] In a circuit configured such that one of forward converters connected in antiparallel is appropriately selected to supply current to a load, it is determined whether the load current value immediately before the forward converter is turned on is 0 or not. If the detection result is 0, the pre-starting converter is switched, and the first firing angle immediately after switching is set by subtracting the firing angle immediately before switching from a predetermined value. A load current switching method for an inverse-parallel connected forward converter characterized by