JPS6323568A - Starter unit for pwm converter - Google Patents

Abstract

PURPOSE:To enable automatic starting when this apparatus is started or after it is conducted again, by switching ON said apparatus after completing charge of a capacitor and by causing information from a memory to be inputted to an operating information detecting circuit. CONSTITUTION:When this apparatus is started, a memory circuit 4 is reset by a resetting circuit 6. An AND circuit 7 supplies an AND circuit 8 with an AND signal of an output memory circuit 4 and a signal indicating that there is no trouble such as overload and overheat. A delay circuit 9 receives an AND signal of an output signal of the AND circuit 8 and a signal indicating that a switch 68a of a presetting circuit is closed. An AND circuit 10 is given an output of the delay circuit 9. Further, if a logical product of an operation command signal and a DC setting signal is obtained by AND circuits 11 and 12 and a switch 3 is turned ON by an output of the AND circuit 12, then an AND circuit 2 and the memory circuit 4 are connected.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a starting device for a PWM converter.

B1 Summary of the Invention The present invention provides a starting device for a PWM converter, which includes a blood flow/AC input for detecting DC and AC inputs between the three-phase commercial power supply and the AC reactor and between the DC/AC conversion circuit and the capacitor. Detection-path is fully connected, the DC/AC input detection circuit is connected to a switch via an AND circuit, and the switch is connected to a memory circuit to detect operating information.
The operation information detection circuit is connected to the switch to prevent malfunction during starting due to inrush current, and also to prevent the converter u from malfunctioning due to rush current.
It is possible to automatically start at startup and when power is restored without having to stop the system.

C1 Prior Art FIG. 2 is a circuit diagram showing an example of a PWM conversion device disclosed in Japanese Patent Laid-Open No. 55-94583. In this figure, reference numeral 50 denotes a three-phase commercial power supply, and this three-phase commercial power supply is used as a source 50.
An AC reactor 52 is connected to the AC reactor 52 via a three-phase AC circuit 51. Connected to the current transformer reactor 52 is an AC/DC conversion circuit 53 in which a switching element such as a transistor and a diode are connected in antiparallel. Also, connected to the AC/DC conversion circuit 56 are a capacitor 54 and a load 55. In this PWM conversion device, a phase voltage detector 56 is connected to the three-phase AC circuit 51, and a first multiplier 57 is connected to the phase voltage detector 56. The current transformer 5 is inserted into the three-phase AC circuit 51.
At 8, a first comparator 58 is connected to the current transformer 58.

A deviation device 60 is connected to the discharge voltage supply section 54a of the capacitor 54. A control amplifier 6 is connected between this deviation device 60 and the second multiplier 57.
1, the first one is connected in parallel to the control amplifier 61.
, second and third multipliers 57, 62, and 63. First,
The second and third multipliers 57.62.66 include the first, second,
A third comparator 59, 64, 65 is connected respectively. The current transformer 66 connects the DC/tributary current conversion circuit 53 and the load 55.
It is inserted between.

This PWM converter is a so-called instantaneous current value control type converter, and operates as follows.

In this PWM converter, all AC voltage is supplied from a three-phase commercial power supply 50 to an AC/DC converter circuit 56 via an AC reactor 52, and the AC/DC converter circuit 53 converts the AC voltage to a DC voltage. In this PWM converter, the converted DC voltage is supplied to the capacitor 54 to the mystery deviation device 60 as the DC voltage detection value vDc. The deviation device 60 obtains a deviation voltage from the difference between the DC set voltage vDc* and the DC voltage detection 5 VDC. The control amplifier 61 amplifies the deviation voltage, and the first, second, and third multipliers 57, 62, 63
Apply the entire amplified deviation voltage to. In the first, second, and third multipliers 57, 62, and 63, the amplification deviation voltage and phase voltage detector 56
The detected phase voltage is fully multiplied and the current command I"e is supplied to the comparator 58, 64, 65.

In addition, in this PWM converter, the comparator 58°64
．． The current output from 65 connects the U and X phase gate circuits,
Controls the switching elements of the V and Y phase gate circuits and the W and Z phase gate circuits.

FIG. 3 is a circuit diagram showing a modified example of a conventional PWM conversion device.

In this figure, a wall current transformer 667 is inserted into the three-phase AC circuit 51, and this current transformer 67 is connected to an AC current detector tAc oc'rt (not shown). Also,
A precharge circuit 68 is connected between the father current/direct m vibration converter 56 and the load 55, and this precharge circuit 68 is connected in parallel to a switch 68a and a current limiting resistor 68b'. .

In this PWM converter, when the switching element of the AC/DC converter 56 malfunctions and short-circuits, a short-circuit current flows from the capacitor 54 to the current-limiting resistor 68b of the precharge circuit 68, and the switch 68a becomes open. Therefore, the present conversion device can prevent overcurrent from flowing through the circuit even if the switching element malfunctions.

Next, a method for starting a conventional PWM converter will be described.

In conventional PWM converters, the DC voltage can only be controlled by converting the input AC voltage into a voltage rectified by a diode bridge (in the case of Figure 2, it is approximately 1.35 times the input voltage, which is a voltage 2 or higher). Therefore, in such a PWM converter, first, 50t of three-phase commercial power is turned on, and after rectifying the voltage of the capacitor 34, the converter is started and controlled to the DC set voltage VDC*.In this case, vDc* voltage will be higher than the rectified voltage.

D1 Problems to be solved by the invention However, in the method for starting such a PWM conversion device,
When the three-phase flexible power supply 50 is turned on, as the charging current of the capacitor 54 (so-called "rush current") increases, the surge voltage of the diode element used in the AC/DC conversion circuit 56 may increase, causing a problem. was. Therefore, in order to prevent the total surge voltage from increasing, a circuit shown in FIG. 3 has conventionally been used in a PWM converter. However, in this method of starting a PWM converter, the variation m (dv/
dt, etc.) may cause the transistor wires to malfunction, so it is necessary to maintain a reverse bias between the base and emitter. In addition, in the starting method of this PWM converter, when the switch 68a is turned on, the control system (protection circuit, etc.)
All circuits are in the starting state, and the current transformer input detection circuit (AC0CTJ or DC input detection circuit + DCOCT) K
Since an inrush voltage for voltage charging of about 10 to 15 - is supplied, there is a problem that the engine cannot be started unless it is brought into a - charge reset state.

Incidentally, the above problem occurs not only at the time of starting but also when restarting the engine after power is restored due to the load.

An object of the present invention is to provide a starting device for a PWM converter that automatically starts at startup or after power is restored.

Means for Solving All E0 Problems As a means for solving the above problems, the present invention provides three-phase commercial 1! PWM conversion in which a source is connected to an AC reactor via an AC circuit, connected to an AC/DC conversion circuit in which all switching elements and diodes of the AC reactor are connected in antiparallel, and a capacitor is connected to the AC/DC conversion circuit. A starting device for the device, wherein a DC/AC input detection circuit for detecting all DC and current transformation inputs is connected between the three-phase commercial power supply and the AC reactor and between the DC/current transformation conversion (b) path and the capacitor. The DC/AC input detection circuit is connected to a switch via an AND circuit, and the switch is connected to an operating information detection circuit that detects operating information via a memory circuit, and the operating information detection circuit is connected to the switch. All percentages are connected.

F6 action The starting vct of the PWM conversion device prevents malfunctions during starting due to inrush current, and can automatically start at the time of starting and when power is restored without stopping the conversion bag &.

G. Embodiment Next, an embodiment of a method for starting a PWM converter according to the present invention will be described in detail based on the accompanying drawings.

Regarding the PWM conversion device, the explanation in the related art will be referred to, and the explanation will be omitted here.

FIG. 1 is a block diagram showing an embodiment of a method for starting a PWM converter according to the present invention. The chain line portion in the figure is the driving information detection circuit. In this figure, reference numeral 1 denotes an AC/DC input detection circuit, and this AC/DC human power detection circuit 1 detects both AC input overcurrent and DC input overcurrent. The first AND circuit 2 is connected to the switch 6 and applies an AND signal of an AC input overcurrent and a DC input overcurrent to the switch 3. The switch 6 is formed by an analog switch or the like. A reset circuit 6 is connected between the switch 6 and the memory 4 via a resistor 5, and the reset circuit 6 sends a reset number 100 to reset the PWM converter at startup. Supplied to the memory circuit 4. The second AND circuit 7 is connected to the output signal 101 of the memory circuit 4, which indicates that there is no failure such as overload or overheating.
02 AND signal 106 is input to the third AND circuit 8. The delay circuit 9 receives the AND signal 106 and the AND signal 105 of the switch 68a of the recent circuit 68 (see FIG. 3), the switch closing completion signal 104 indicating the completion of closing J. The logic f of the product signal 106 and the signal 107 indicating that no instantaneous power outage or phase loss occurs.
*Input the multiplied signal 08 to the fifth AND circuit 11. Fifth
The AND circuit 11 outputs an AND signal 110 of the AND signal 108, the operation command signal 108 of the PWM converter, and the operation command signal 109 of the PWM converter. This AND signal 110 is a gate cutoff release command signal. In the sixth AND circuit 12, when the AND signal 112 of the AND signal 110 and the DC setting signal 111 exceeding 0.9 times the DC setting voltage VDc* is output, the switch 3 is closed and the 1's AND circuit 2 and memory circuit 4 are connected.

Next, the operation of the fifth embodiment will be explained.

Before the three-phase commercial power supply 50 is turned on, the capacitor 54
The voltage is Ov, and the DC setting signal 111 becomes low level, that is, "0". Therefore, the output of the sixth AND circuit 12 becomes low level, cutting off the switch 6.

When the 1-3 phase commercial power supply 50 is turned on, the precharge circuit 68 shown in FIG. 3 is operated. Precharge circuit 6
8 operates, the voltage of the capacitor 54 increases,
Fully turn on switch TSAA.

Then, the switch-on completion signal 104 is input to the third AND circuit 8. At this time, if there is no failure such as overload or overheating, the logical product output 10 of the second AND circuit 7
6 is set to a high level, that is, "1", and the AND output 105'ft of the third AND circuit 8 is set to a high level. After the switch 68a is turned on, the delay circuit 9 outputs the remaining 10 to 1
Set the entire delay time when the inrush current for 5% voltage charging ends. Therefore, the AND output 10 of the third AND circuit 8
5 is delayed by the set time and input to the fourth AND circuit 10. At this time, if no instantaneous power outage or phase loss has occurred, the AND output 108 of the fourth AND circuit 1o is set to a high level. If the operation command signal 109 is input to the fifth AND circuit 11, the AND output 110 is set to a high level, and a gate (not shown) of a transistor or the like is made conductive. In this way, the PWM converter operates,
The voltage of the capacitor 54 is controlled by the set DC voltage VDC*. Also, depending on the starting method of this PWM converter,
Since the DC setting (N 111 is switched from low level to high level, at this time, the AND output 112 of the sixth AND circuit 12 is all set to high level. Then, the switch 3 is closed and the AC/DC input A signal input to the detection circuit 1 is input to the second AND circuit 7 as an output signal 101 via a memory circuit.

According to the method for starting the PWM converter of this embodiment, the switch 6 is turned on after charging of the capacitor 54 is completed, so that the inrush current for charging the remaining voltage of about 10 to 15% causes @1 to be turned on. The logical product output 116 of the AND circuit 2 can be set to a low level, and the output signal 101 of the memory 4 can be set to a low level. Therefore, unless the reset circuit 100 is input from the reset circuit 6 to the memory 4, the output signal of the memory circuit 4 can be held at a low level.

Furthermore, depending on the starting method of the present PWM converter, the converter can operate in the same way even when the converter is required to start automatically due to power restoration, for example. 2. That is, when a power outage occurs, the signal 107 of the fourth AND circuit 10, which indicates that there is no momentary power failure or phase loss, becomes low level, that is, "o", and at this time, the logical product of the fifth AND circuit 11 Since the output becomes low level, the gate circuit (not shown) is completely shut off and the operation of the PWM conversion device is stopped. At this time, the charge in the capacitor 54 is discharged to the load 55, gradually lowering the voltage. When the discharge is finished, the switch 68 is opened. According to the starting method of this PWM conversion device, the fifth
Since the AND output 110 of the AND circuit 11 is set to low level and the DC setting signal 111 is set to low level, the switch 6 becomes open. When the power is restored, the signal 107 indicating that there is no instantaneous power outage or phase loss immediately goes to a high level, that is, "1", and the starting operation is performed in the same way. Therefore, the PWM conversion device can be started regardless of the signal manually input to the AC/DC input detection circuit 1, since the level becomes high at the time of automatic start after the operation command of the fifth AND circuit 11 is restored. .

If you want to start the PWM converter automatically after returning to %L, either turn on the control unit within a certain guaranteed time, or turn off the power supply from the control unit at the same time as the main circuit is turned on. There is no need to supply it at 7.

How to Start the PWM Converter of this Example According to the starting method of the Conversion Association, it is possible to completely prevent malfunctions at the time of starting due to the inrush current that is unique to PWM converters. Automatic start can be performed at startup or in the event of a power restoration failure without having to completely stop the system.

H1 Effects of the Invention As described above, according to the present invention, it is possible to prevent malfunctions at startup due to rush current specific to PWM converters. Further, according to the present invention, it is possible to automatically start the PWM conversion V& device at startup and return without stopping the device.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a block diagram showing an embodiment of a method for starting a PWM conversion device of the present invention, FIG. 2 is a circuit diagram showing an example of a conventional PWM conversion device, and FIG. It is a circuit diagram showing a modified example of the PWM conversion device. DESCRIPTION OF SYMBOLS 1... AC/DC input detection circuit, 2... Second AND circuit, 6... Switch, 4... Memory circuit, 5...
...Resistor, 6...Reset circuit, 7...Second AND circuit, 8...Third AND circuit, 9...Delay circuit, 10...Fourth AND circuit, 11... ...Fifth AND circuit, 12...Sixth AND circuit.

Claims (1)

[Claims] A three-phase commercial power source is connected to an AC reactor via an AC circuit, the AC reactor is connected to an AC/DC conversion circuit in which a switching element and a diode are connected in antiparallel, and a capacitor is connected to the AC/DC conversion circuit. becomes PWM
In the starting device of the converter, a DC/AC input detection circuit for detecting DC and AC inputs is connected between the three-phase commercial power supply and the AC reactor and between the DC/AC conversion circuit and the capacitor, and the DC/AC input detection circuit detects the DC/AC input. An input detection circuit is connected to a switch via an AND circuit, and the switch is connected to a driving information detection circuit that detects driving information via a memory circuit, and the driving information detection circuit is connected to the switch. A starting device for a PWM converter.