JPS63198592A - Control of commutatorless motor - Google Patents

Abstract

PURPOSE:To operate a motor again smoothly, by setting the command value of the angle of lead for an inverter at normal set point of the angle of lead by changing it gradually from the neighbourhood of 90 deg. when the motor is changed over from short-circuit mode to normal pulse distribustion. CONSTITUTION:A thyrister starting device of a commutatorless motor performs driving operation to the synchronous speed of motor and the control operation to stop it from the synchronous speed. In case any system failure occurs, such as the failure of communication, etc., while the motor is in driving operation, the control device sets the DC current to zero, and then starts operation again. On this occasion, in the control device its drive/brake changeover switch 1 is changed over in accordance with the braking mode of the motor, of which the output side is connected to a striking pulse generation circuit 3 through an angle-of-lead setting filter 2 to perform the preset action setting the angle-of- lead command value b to a definite value. By changing this angle of lead from the neighbourhood of 90 deg. gradually so that it will get to a normal angle-of-lead set point, the stepwise change of DC voltage can be prevented.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a control device for a commutatorless motor.

(Prior Art) A so-called thyristor starting device has conventionally been used to start/stop large-capacity pumps, blowers, and generator motors for pumped storage power generation. The thyristor starting device drives the motor to a synchronous speed and performs a braking operation to stop the motor from the synchronous speed. In the figure, 11 is a grid-side (power supply side) power converter (hereinafter referred to as "converter") consisting of a three-phase bridge-connected thyristor;
Similarly, 11. is a motor-side power converter (hereinafter referred to as "r-inverter") consisting of a three-phase bridge-connected thyristor, and these converters 11. A DC current smoothing reactor (Ld) 13 is provided between the inverters 12 .

A three-phase synchronous motor 14 (or a three-phase synchronous generator motor) is connected to the inverter 12, and this synchronous motor 14 is provided with a position detector 15 and a speed detector 16. The control device 17 is configured to send a firing pulse to the gate of each thyristor of the converter 11 and inverter 12 based on the magnetic pole position detection signal and the speed detection signal from each detector 15,16.

In such a system, if a system failure such as commutation failure occurs during driving operation of the synchronous motor 14, the control device 17 may restart the operation after once reducing the DC current to zero. In this case, if normal pulse distribution is immediately performed on the inverter 12 side based on the magnetic pole position and the operation is restarted, the DC voltage Vdi on the inverter 12 side will be
Since the DC current counteracts the DC output voltage Vdc of 1 in the opposite direction, the rise of the DC current becomes slow, and a current intermittent state, which is undesirable for a high-voltage power converter, may occur.

Therefore, when restarting the synchronous motor 14 while it is rotating at high speed, certain upper and lower arms of the inverter 12 (for example, U
X arm) is ignited to short-circuit the arm, and Vd1=
The DC current Id is quickly raised as O to prevent a current intermittent state from occurring, and the pulse distribution of the inverter 12 is switched from the arm short circuit mode to the normal pulse distribution after the DC current Id has sufficiently risen. Ru.

Also, during braking operation, a similar switch from the arm short-circuit mode to the normal pulse distribution mode is performed.

FIG. 6 shows the main parts of the conventional control device 17 described above, and the firing pulse generation circuit 21 generates firing pulses to the individual thyristors of the inverter 12 in accordance with the advance angle command value. The switch 22 switches the advance angle command value depending on whether the operation mode of the synchronous motor 14 is driving or braking, and selects the command value βX in the reverse conversion operation region when driving, and the command value α8 in the forward conversion operation region when braking. works. Also.

a is a command to select a short circuit of a specific upper and lower arm of the bridge-connected thyristor arms U-Z, for example, the UX arm, and when this command is 111)l, the ignition pulse generation circuit 21 short-circuits the UX arm. A short circuit is selected and a predetermined ignition pulse is output to the inverter 12.

(Problems to be Solved by the Invention) However, in this control device 17, the advance angle command value is given as a constant value when switching the UX arm from the short-circuit mode to the normal pulse distribution.

The DC voltage Vdi on the inverter 12 side changes stepwise immediately after switching, which causes a large disturbance to the current control system, causing a sudden decrease in DC current during driving and a sudden increase in DC current during braking, resulting in an intermittent current state or overcurrent state. There was an inconvenience that caused

For example, FIG. 7 shows the DC current Id during braking operation.

It is a waveform diagram showing the relationship between converter 11 side voltage Vdc and inverter 12 side voltage Vdi, and ignition pulse generation lI
21 is the inverter 12 for restarting at t=t1' in the figure.
Give the ignition pulse for shorting the UX arm to the side. At the same time, control on the converter 11 side is started, and the DC current I
After d has risen sufficiently, the inverter 12 at t=t,'
Switch the operation to normal pulse distribution. However, according to this, as shown in the figure, the DC voltage Vd on the inverter I2 side
Since i changes stepwise immediately after time t,'', the DC current Id increases rapidly from the same point.Furthermore, such a state will not occur when the commutatorless motor system is restarted when the motor is being driven. , this occurs as a sudden decrease in the DC current Id.

The present invention has been proposed in order to solve the above-mentioned problems. For example, in a control device for a non-commutator motor such as a large-capacity thyristor starter, when restarting the motor while it is rotating, the inverter It is an object of the present invention to provide a control device for a commutatorless motor that enables smooth control without causing a rapid decrease in direct current when switching from an arm short-circuit mode to a normal pulse distribution mode.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides an f! Controls the firing angle of the thyristor constituting the motor side power converter according to the firing angle command value,
and distributes a firing signal for short-circuiting the upper and lower arms of the motor-side power converter to the thyristor according to the upper and lower arm short circuit command, and switches from this short circuit mode to a normal drive mode or braking mode based on the firing angle command value. ignition signal distribution means for distributing an ignition signal for continuous transition;
and an advance angle setting filter that inputs a firing angle setting value corresponding to the driving mode or braking mode and outputs the firing angle command value while changing the firing angle command value, and the firing signal distributing means has an upper and lower firing angle. In response to the arm short circuit command, a firing signal is output to the specific upper and lower arms, and a signal is output to the lead angle setting filter to preset the firing angle command value to a preset value. The firing angle is controlled by turning off the upper and lower arm short circuit command after the direct current as an output has sufficiently risen, and changing the firing angle command value from the time when the first firing signal is output thereafter. There is.

(Function) In the present invention, when the DC voltage of the power converter (inverter, converter) is set to zero when restarting the motor system during driving or braking operation of a non-commutated motor, the DC current rises quickly. , the arm on the inverter side (for example, the UX arm) is short-circuited by the upper and lower arm short-circuit command. At this time.

A preset signal of the lead angle command value is given to the lead angle setting filter of the control device.Next, the DC current is set to a predetermined value (
For example, when reaching 50% of the rated value, the upper and lower arm short circuit command is turned off, and then the preset signal is turned off to enable the filter operation of the lead angle setting filter, and the lead angle is commanded according to the lead angle setting value. Distributes the ignition pulse in gradually changing values. As a result, the DC voltage on the inverter side gradually rises, and the DC current does not change suddenly.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a block diagram showing the entire non-commutator motor system to which the present invention is applied. In FIG. (referred to as "converter"), 5 is also 3
This is a motor side power converter (hereinafter referred to as an "inverter") consisting of a thyristor connected in a phase bridge. These converters4. A DC current smoothing reactor (Ld) 6 is provided between the inverters 5 . A three-phase synchronous motor 7 is connected to the inverter 5, and the synchronous motor 7 is provided with a position detector 8 and a speed detector 9 for detecting its magnetic pole position.

Furthermore, in order to obtain a synchronization signal for controlling the firing angle of the converter 4 and an actual current value for current control and monitoring, a voltage transformer 41 and a current transformer 42 are installed on the three-phase AC power supply side of the converter 4. It is provided.

Position detector8. Speed detector9. Voltage transformer 41 and current transformer 42 are connected to a control device 10 which receives position and speed detection signals from each detector 8, 9 and synchronized voltage and current signals from transformers 41, 42. It is arranged to send a firing pulse to the gate of each thyristor of the inverter 5 and the converter 4 on the basis of the actual value signal. Although not shown in the drawings, the control device 10 has a built-in speed regulator and a current regulator as is well known.

FIG. 1 is a block diagram showing the main parts of the control device 10. In FIG. The lead angle setting filter 2 is connected to the advance angle setting filter 2, and the changeover switch 1 allows the advance angle setting filter 2 to be set to α1 braking mode) or β positive drive mode).
The value of is output as the advance angle setting value C.

The lead angle setting filter 2 is a first-order lag filter, and its output side is connected to the ignition pulse generation circuit 3 and outputs the advance angle command value d, while also receiving a preset signal d from the ignition pulse generation circuit 3. In response to this, the one-firing pulse generation circuit 3 performs a preset operation to set the lead angle command value to a constant value, and the one-firing pulse generation circuit 3 distributes the pulses of the normal commutatorless motor, and also distributes the pulses of the inverter 5 by the UX arm short circuit command a. It has the function of outputting a firing pulse that short-circuits the UX arm, and continuously changing the phase of the firing pulse according to changes in the advance angle command value.

Now, as an example, a case where the synchronous motor 7 is restarted in the braking mode will be described below.

First, in FIGS. 2 and 3, when the restart is started at time 1=18, a UX arm short circuit command a is given to the one-firing pulse generation circuit 3. Then, the UX arm of the inverter 5 becomes conductive due to the ignition pulse from the ignition pulse generation circuit 3, and Vd1=0, and the DC current Id starts to flow under the control of the converter 4 side. Further, after time t□, the ignition pulse generation circuit 3 outputs a preset signal d to the advance angle setting filter 2. As a result, the advance angle command value is set to correspond to the predetermined control advance angle β=90°. On the other hand, the DC current Id is 1=1. If a predetermined value (for example, 50% of the rating) is exceeded at any point in time, this is detected by a current monitoring means (not shown).

The zero-firing pulse generation circuit 3 whose UX arm short-circuit command a is canceled starts an operation to return to normal pulse distribution as the UX arm short-circuit command a is canceled.

That is, as shown in FIG. 3, at the time of transition to normal pulse distribution, the first commutation point from the U phase to the V phase or from the X phase to the Y phase of the inverter 5 (the first commutation based on the normal firing angle control operation) DC voltage Vdi starts to be generated from the point in time when the corresponding ignition signal is generated. Therefore, at this commutation point (1=1.), by turning off the preset signal d and releasing the preset value constraint state as shown in FIG. 2, the advance angle setting filter 2 is caused to perform its filter operation. . As a result of these operations, at time t, the lead angle command value is set to the preset value β=90 according to the time constant of the lead angle setting filter 2.
Since this embodiment describes a braking mode in which the advance angle gradually approaches the advance angle set value C from .degree., the advance angle command value S approaches αX.

The DC voltage Vdi gradually changes to a normal voltage level by the operation of the ignition pulse generating circuit 3 in accordance with the change in the advance angle command value S. At this time, if the time constant of the advance angle setting filter 2 is made slower than the response of the current system on the converter 4 side, the DC current Id will not change suddenly and the inverter 5 will switch from the UX arm short-circuit mode to the normal pulse distribution. This allows for smooth operation.

(Effects of the Invention) As described above, according to the present invention, when switching from the upper and lower arm short-circuit mode of the inverter to the normal pulse distribution, the inverter lead angle command value is gradually changed from around 90° to maintain the normal lead angle. Since the control device is configured to match the angle setting value, it is possible to prevent the DC voltage on the inverter side from changing in a step-like manner, allowing smooth restarts without causing the sudden increase in DC current as in the conventional case. It becomes possible to do so.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention,
FIG. 1 is a block diagram of the main parts, FIG. 2 is a timing chart showing each signal in FIG. 1, and FIG. 3 is a waveform diagram showing the relationship between current and voltage of the power converter in braking mode.
Figure 4 is a configuration diagram showing the entire non-commutator motor system;
Figures 5 to 7 show conventional examples. Figure 5 is a block diagram showing the entire non-commutator motor system, Figure 6 is a block diagram of the main parts of the control device, and Figure 7 is the braking mode. FIG. 3 is a waveform diagram showing the relationship between current and voltage of the power converter in FIG. 1... Drive/brake changeover switch 2... Advance angle setting filter 3... Firing pulse generation circuit Figure 2 jltz ts

Claims (1)

[Claims] A control device for a commutatorless motor that outputs firing signals to thyristors constituting a power converter on the power source side and a power converter on the motor side in response to signals from a magnetic pole position detector and a speed detector. A point for controlling the firing angle of a thyristor constituting the motor-side power converter according to a firing angle command value, and short-circuiting the upper and lower arms of the motor-side power converter by an upper and lower arm short circuit command. ignition signal distribution means for distributing an arc signal to the thyristor for continuous transition from the short circuit mode to a normal drive mode or braking mode based on the ignition angle command value; The firing signal distribution means is provided with an advance angle setting filter that inputs a firing angle setting value corresponding to the driving mode or braking mode and outputs the firing angle command value while changing the firing angle command value, and the firing signal distribution means A firing signal is output to the specific upper and lower arms, and a signal is output to the advance angle setting filter to preset the firing angle command value to a preset value, and the signal is output as an output of the power converter on the power source side. A non-rectifying device characterized in that the firing angle is controlled while changing the firing angle command value from the time when the upper and lower arm short circuit command is turned off after the direct current has sufficiently risen and the first firing signal is output thereafter. Control device for sub-motor.