JPH09182438A - Converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a converter in which an inrush current is suppressed when a converter is started. SOLUTION: In a converter apparatus, the deviation ΔVDC between a DC voltage instruction value VDC* and a DC voltage detection value VDC is detected, and the Self-arc-extinguishing device of a converter is PWM-controlled. In the converter apparatus, a circuit 11 which converts input currents IR, IS, IT of the converter into a peal value ID, an adder 13 by which the voltage detection value VDC and a very small voltage Vmin and the peak value ID are added so as to output a DC voltage instruction value and a limiter 14 which limits its output to the value of an ordinary instruction value are installed. Since an input current at a start is 0, the instruction value is VDC*=VDC+Vmin , and the deviation is ΔdVDC=Vmin . When the input current is increased, the value VDC* is increased. When the value VDC* exceeds the limit value of the limiter 14, it is limited to the ordinary instruction value. Consequently, when the voltage Vmin is made small, the deviation ΔVDC at the start can be made small and an inrush current can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a converter device capable of suppressing inrush current at startup.

[0002]

2. Description of the Related Art As shown in FIG. 8, a conventional three-phase converter device has a converter A in which a self-extinguishing element SS is connected in a three-phase bridge and a diode D is connected in antiparallel to each element SS.
And a control section B for controlling the gate of the element SS, an input reactor L, a smoothing capacitor C _{DC and the} like.

The control unit B controls the input voltage V _{R of the} converter,
V _S, V _T, the input current I _R, I _S, by reading the signals of I _T, and the output DC voltage V _DC, creates a gate signal for switching the converter self-turn-off devices SS.

The gate signal generated by the control unit B causes the DC voltage V _DC to be boosted to a certain constant value by switching the self-extinguishing element SS of the converter A, and a current flowing using the input reactor L. Is set to a normal arc wave and the input power factor is controlled to approximately 1.

[0005] The control unit B, as shown in FIG. 9, * DC voltage command value V _DC during converter operation (constant value) and the deviation of the current detected DC voltage value V _DC △ V _DC deviation detector 1
6 and the deviation ΔV _DC and the detection value V _R (or V _S , V _T ) synchronized with the input phase voltage waveform detected by PT etc. are multiplied by the multiplier 2 to obtain the current command value I *. create detects phase current values detected by the current command value I * and the CT, etc. I _R (or I _S, I _T) the deviation △ I of the adder 3, the deviation △
I is input to the PWM creation circuit 4 to create a PWM waveform,
A gate signal is output via the gate drive circuit 5.

The gate drive circuit 5 cuts off the gate signal when the converter A is not operated by the RUN (operation) signal (the self-extinguishing element SS is not switched).

[0007]

In the above-mentioned conventional apparatus,
When the converter is started, an inrush current flows in a certain phase, and when an attempt is made to increase the DC voltage, an overshoot occurs temporarily and a voltage larger than the command value is generated.

[0008] The reason is that, because of the DC voltage command value V _DC * is a constant value, at the time of start-up converter, the DC voltage command value V _DC
There is a deviation ΔV _DC (= V _bc * -V _bc ) between the * and the DC voltage detection value V _DCSAT at the time of stop just before starting, and the multiplier 2 _{outputs the} current command I *, but the phase current I _R (or I _S, since I _T) is O, and deviation from the subtracter 3 △ I (= I *) is out. This deviation ΔI becomes maximum when the input voltage V _R (or V _S , V _T ) is at the peak, and a large inrush current flows at the start-up as shown in FIG.

There is no problem if the value of the inrush current is small, but if the value is large, the self-extinguishing element may be destroyed. Further, since the DC voltage also becomes an overvoltage, the breakdown voltage of the main circuit components such as the converter and the load thereof, such as the inverter, becomes a problem.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a converter device capable of suppressing an inrush current at the time of starting.

[0011]

SUMMARY OF THE INVENTION The converter device of the present invention includes a DC voltage command value circuit (1) so that the deviation between the DC voltage command value and the DC voltage detection value becomes small when the converter is started. Means for obtaining a DC voltage command value by adding a value according to the peak voltage of the input current to the DC voltage detection value of, and a limiter for limiting when the DC voltage command value exceeds a target value Or (2) storage means for storing the detected DC voltage value before the converter is started, and the difference between the final command value of the DC voltage and the stored detected DC voltage value before the converter is started when the converter is started. The calculating means and the adding means for adding the difference to the DC voltage detection value before the converter is started via the time constant to output the DC voltage command value, or (3) the converter Means for integrating the minute voltage at the time of starting the motor, adding means for adding the integrated voltage to the DC voltage detection value of the converter and outputting the DC voltage command value, and the DC voltage command value exceeds the target value. It consists of a limiter function that limits the load.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. 1 shows the configuration of a DC voltage deviation detection unit in a converter device.

Referring to FIG. 1, 1 _A is a DC voltage deviation detection unit for suppressing inrush current, which is an input current I of the converter.
_R, I _S, current peak value converting circuit for converting the I _T to the current value I _P corresponding to the peak value, 13 small required current flows when the detection value V _DC and the converter startup of the DC voltage of the converter The voltage value Vmin and the current value _ID from the conversion circuit 11 are added to output a DC voltage command value, and the DC voltage command value from this adder 13 is a DC voltage command during normal operation of the converter. A limiter circuit 14 for limiting when the value V _DC * is exceeded, and a deviation ΔV _DC between the DC voltage command value V _DC * from the limiter circuit 14 and the DC voltage detection value V _DC is detected and the multiplier 2 of the prior art FIG. The deviation detector 16 outputs to the.

The operation of FIG. 1 will be described. When the converter is started, the current outputs I _R , I _S , and I _T of the converter are 0. Therefore, when there is no voltage Vmin, the input of the output limiter 14 from the adder 13 is only the voltage detection value V _DC , and the limiter 14 outputs. Since the voltage command V _PC * = V _DC , the deviation ΔV _DC from the deviation detector 16 becomes 0, and the current command I * is not output from the multiplier 2 (FIG. 9), so no current flows through the converter. Since a slight voltage Vmin is applied to the adder 13, the deviation ΔV _DC = Vmin is output and the multiplier 2
A current command I * is output from the current source and a current flows through the converter.

When a current flows through the converter, the conversion circuit 1
The current value I _D corresponding to the peak value of the current is output to the adder 13 from 1 and added together with the voltage detection value V _DC and the voltage Vmin, and the voltage command value is output from the adder 13, so the deviation detector Deviation ΔV _DC comes out from 16. When the current increases, the DC voltage command value from the adder 13 increases. When this command value rises to the final target value (DC voltage command value during normal operation), it is limited by the limiter 14.

[0016] As described above, since by increasing the DC voltage command value V _DC * from a low value to a final target value to start the converter, as shown in FIG. 3, the deviation of the startup △ V _DC (= V
_DC * -V _BC ) becomes smaller and the current command I * becomes smaller, so the current deviation ΔI also becomes smaller and the inrush current is suppressed.

The DC voltage deviation detecting section 1 _A is composed of the circuit shown in FIG. That is, current peak value converting circuit 11 using a full-wave rectifying diode bridge (D ₁ ~D ₆₎ an amplifier A1 and the amplifier A1 output diode D _7, current I _R, I
_{When S} and _IT are respectively positive, they are outputted from the diodes D ₁ , D ₂ and D ₃ , and when they are negative, the currents flowing in the diodes D ₄ , D ₅ and D ₆ are inverted by the amplifier and outputted through the diode D _7. I did it. A sum amplifier was used for the adder 13 and the deviation detector 16. As the limiter 14, a symmetrical limiter in which a Zener diode (ZD × 2) is connected between the input and output of the amplifier A4 is used. Further, inversion amplifiers 12 and 12 are used for matching the polarities.

Embodiment 2 FIG. 4 shows a DC voltage deviation detection unit 1 _B for suppressing inrush current in the converter control unit. 21 in the figure is RU
A memory circuit that stores the DC voltage detection value V _DC via the switch SW1 that is turned off at N (operation), and 22 indicates the DC voltage set value V _DC * (ref) and the DC voltage detection value V _DC ′ from the memory circuit 21. An adder for detecting the difference, 23 is a time constant circuit to which the difference voltage from the adder 22 is input via the switch SW2 which is turned on by RUN, and 24 is a DC voltage detection value V _DC ′ from the memory circuit 21 and the time constant circuit. adder for adding the voltage from 23, 16 in the deviation detector for detecting a deviation △ V _DC between the DC voltage command value V _DC * and the DC voltage detected value V _DC from the adder 24, the deviation △ V _DC Is input to the multiplier 2 as in the case of FIG.

The operation of FIG. 4 will be described. The DC voltage detection value V _DC at the time of stop is stored in the memory circuit 21 via the switch SW1 at the time of stop, and the stored value V _DC ′ is added to the adder 22,
24 is output.

When started, the switch SW1 turns off,
The switch SW2 is turned on. When the switch SW1 is turned off, the stored value V _DC ′ output to the adders 22 and 24 becomes the DC voltage detection value V _DCSAT at the time of stop just before the start.

When the switch SW2 is turned on, the set value V _DC *
The difference voltage between (ref) and the stored value V _DC ′ is the time constant circuit 23.
The voltage which is gradually increased from 0 to the differential voltage value ΔV ′ in a time constant is output from the time constant circuit 23, and is added to the stored value V _DC ′ by the adder 24. Therefore, the voltage is output from the adder 24. DC voltage command value V _DC *
_The time constant increases from _DCSAT to the DC voltage set value _VDC * (ref), and finally _VDC * = _VDC * (ref).

That is, at start-up, the DC voltage command value V _DC *
Changes as shown in FIG. 3 as in the case of FIG.
The inrush current of the converter is suppressed.

The DC voltage deviation detecting section 1 _B is composed of the circuit shown in FIG. That is, the field effect transistors FT1 and FT2 are used for the switches SW1 and SW2, and the memory circuit 21 is composed of the memory capacitor C ₁ and the amplifier A7. The adders 22 and 24 and the deviation detector 16 are sum amplifiers. The time constant circuit 23 is composed of time constants R ₂ and C ₂ and an output amplifier A9. Further, inversion amplifiers 15 and 25 are used to match the polarities.

Embodiment 3 FIG. 6 shows a DC voltage deviation detection unit 1 _C for suppressing inrush current in the converter control unit. 31 in the figure is RUN
An integrating circuit for integrating a slight voltage Vmin input via the switch SW3 that is turned on at 32, a DC voltage detection value V
_An adder that adds a DC voltage and a voltage from the integration circuit 31 to output a DC voltage command value, a limiter 14 that limits the DC voltage command value from the adder to a DC voltage command value during normal operation of the converter, and 16 DC voltage command value V from limiter 14
_DC * and detects the deviation △ V _DC of the DC voltage detection value V _DC, which is a deviation detector for the multiplier 2 (see FIG. 2) for outputting a current command I *.

The operation of FIG. 6 will be described. When activated, the switch SW1 is turned on and a slight voltage Vmin is input to and integrated by the integrating circuit 31, and the integrated voltage is added to the DC voltage detection value V _DC by the adder 32 to become a DC voltage command value. Deviation detector 16 outputs the detected deviation △ V _DC between the DC voltage command value V _DC * and the DC voltage detected value V _DC input via the limiter 14 multiplier 2 (see FIG. 1). Then, the current command I * is output from the multiplier, and the current flows through the converter.

The DC voltage command value output from the adder 32 increases with time, and when the final target value is reached, the limiter 1
Limited by 4.

Therefore, when activated, the DC voltage command value V _DC * changes as shown in FIG. 3 as in the case of FIG.
Since the deviation ΔV _DC at startup is small, the inrush current of the converter is suppressed.

The DC voltage deviation detecting section 1 _C is composed of the circuit shown in FIG. That is, the field effect transistor FT3 is provided for the switch SW3, and the integration circuit 31 has a time constant C ₃ ,
An integrating amplifier using R ₃ and a sum amplifier are used as the adder 32. The circuits 14 to 16 were constructed in the same manner as in FIG.

[0029]

According to the present invention, when the converter device is started up, it is possible to start by gradually increasing the DC voltage command value from the value close to the detected DC voltage value at stop just before the start up to the value at the time of normal operation. In addition, it is possible to suppress the inrush current generated at the time of start-up and the overshoot of the DC voltage accompanying it.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a converter control unit according to a first embodiment.

FIG. 2 is a DC voltage deviation detection circuit diagram.

FIG. 3 is a diagram showing a relationship between a DC voltage deviation at startup and a converter current.

FIG. 4 is a configuration diagram of a DC voltage deviation detection circuit according to a second embodiment.

FIG. 5 is a DC voltage deviation detection circuit diagram.

FIG. 6 is a configuration diagram of a DC voltage deviation detection circuit according to a third embodiment.

FIG. 7 is a DC voltage deviation detection circuit diagram.

FIG. 8 is an explanatory diagram of a configuration of a converter device.

FIG. 9 is a circuit configuration diagram of a converter control unit according to a conventional example.

FIG. 10 is a diagram showing a relationship between a DC voltage deviation at startup and a converter current according to a conventional example.

[Explanation of symbols]

1, 1 _A to 1 _C ... DC voltage deviation detection unit 2 ... Multiplier circuit 4 ... PWM creation circuit 5 ... Gate control circuit 11 ... Current peak value conversion circuit 14 ... Limiter 16 ... Deviation detector 21 ... Memory circuit 23 ... Time constant Circuit 31 ... Integrating circuit A ... Converter B ... Control unit SW1 ... Switch turned off by RUN SW2, SW3 ... Switch turned on by RUN

Claims (3)

[Claims] 1. A converter device for controlling a self-extinguishing element of a converter by detecting a deviation between a DC voltage command value and a DC voltage detection value, wherein a circuit for outputting the DC voltage command value includes a DC voltage detection value for the converter. A means for obtaining a direct current voltage command value by adding a value according to the peak voltage of the minute voltage and the input current, and limiting when the direct current voltage command value that increases according to this current value exceeds the target value. A converter device configured with a limiter function, which suppresses the inrush current of the converter and the accompanying overshoot of the DC voltage when the converter is started. 2. A converter device for controlling a self-extinguishing element of a converter by detecting a deviation between a DC voltage command value and a DC voltage detection value, wherein a circuit for outputting the DC voltage command value includes a DC voltage before starting the converter. By storing the detected value, the difference between the final DC voltage command value and the DC voltage detected value before the converter is started is calculated when the converter is started, and the difference is added to the DC voltage detected value before the converter is started via the time constant. By configuring the DC voltage command value by this function and the function to increase the DC voltage command value in a time constant, the converter inrush current and the accompanying DC voltage overshoot are suppressed when the converter is started. Converter device. 3. A converter device for controlling a self-extinguishing element of a converter by detecting a deviation between a DC voltage command value and a DC voltage detection value, wherein a circuit for outputting the DC voltage command value is an integrating circuit at the time of starting the converter. A means to obtain a DC voltage command value by applying a minute voltage to the converter and adding the output of this integrator circuit to the DC voltage detection value of the converter, and a limiter function to limit when this command value exceeds the target value. A converter device configured to suppress an inrush current of the converter and an overshoot of a direct current voltage accompanying the inrush current of the converter when the converter is started.