JPH07107747A - Converter device - Google Patents

Abstract

PURPOSE:To operate a protection circuit in a regeneration converter part only when overcurrent flows through the self-arc-extinguishing element of the regener ation inverter part, which is added to a converter. CONSTITUTION:A regeneration inverter comprising self-arc-extinguishing elements Q21-Q26 is added to a converter 4 comprising diodes D11-D16. In this part, timing detecting circuits 71-73 are provided for current transformers 161-163 of input lines, respectively. The circuit 71 detects the timing when the current flows through the element Q21 with the AND of the output of a current-A- direction detecting circuit 8 and the ON signals, and the element Q21, and detects the timing when the current flows through the element Q24 with the AND of the output of a current-B-direction detecting circuit 9 and the ON signals of the element Q24. By this same way, the timings when the currents flow through the elements Q22 and Q25 and Q23 and Q26 are detected with the circuits 72 and 73. An overcurrent detecting circuit 20 detects the overcurrents of the input lines. When protection is performed with the detected output of the overcurrent under the condition wherein there are outputs from the circuits 71-73, the overcurrent protection can be achieved only when the current flows through the arc extinguishing element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regenerative converter device having an overcurrent protection circuit for protecting an arc extinguishing element of a regenerative inverter section.

[0002]

2. Description of the Related Art An example of a conventional regenerative converter device will be described with reference to FIG. In FIG. 2, 1 is a three-phase AC power source, 4 is a converter composed of a bridge circuit of diodes D _{11 to} D ₁₆ , and a regenerative inverter unit composed of transistors Q _{21 to} Q ₂₅ is added. 5 was connected to the output of the converter 4 to smooth the DC power PN by a capacitor C inverter, 6 motor driven by the inverter 5, 10 control for controlling the transistor Q ₂₁ to Q ₂₅ of the regenerative inverter unit in the converter 4 Circuit.

The inverter section of the converter 4 is controlled as follows. The phase voltage of the three-phase power supply 1 is detected by the transformer 11 and applied to the signal generation circuit 13 through the low pass filter 12. Here, a gate signal is created and given to the gate drive circuit 14 through the gate block circuit 15. The gate drive circuit of the regenerative inverter of the converter 4 by the operation of the fourteenth transistor Q ₂₁ and Q ₂₃ joined by a gate signal, a regenerative operation is performed.

On the other hand, each phase input line current is detected by the AC generators 16 _{1 to} 16 ₃ , rectified by the rectifier circuit 17, and then compared with the current set value from the setter 18. If the rectified value of the line current is smaller than the set value, the output of the comparator circuit 19 allows the signal passing of the gate block circuit 15 to continue.

If the rectified value of the line current exceeds the set value, the comparator circuit 19 operates to send a signal blocking control signal to the gate block circuit 15, and the gate block circuit 15 blocks the gate signal. Therefore, the transistors Q ₂₁ to Q ₂₅ decreases becomes line current and off-state of the regenerative inverter unit.

[0006] line when the rectified value of the current becomes smaller than a set value, since a state of the gate block circuit 15 permits the signal passage, the transistor Q ₂₁ to Q regenerative inverter
_The regenerative operation is performed by ₂₆ .

By performing the gate operation of the transistors Q _{21 to} Q ₂₆ as described above, the peak value of the line current can be suppressed below the set value.

Overcurrent protection of the self-extinguishing elements (transistors Q _{21 to} Q ₂₆ ) of this converter detects the input line current by the current transformer 16, and when there is a possibility that a current exceeding the withstand capacity of the elements may flow, Turn off the gate of the self-extinguishing element,
The current flowing through the self-extinguishing element is suppressed. Reference numeral 20 indicates this overcurrent detection circuit.

When the overcurrent detection circuit 20 detects an overcurrent, the signal is latched and the gate cutoff of the self-extinguishing element is continued. This suppresses the current flowing through the self-extinguishing element and protects the self-extinguishing element from overcurrent. As a result, the regenerative inverter itself stops.

[0010]

In the above converter, the diode and the self-extinguishing element are connected in parallel to form one arm. Therefore, the current of the input circuit detected by the current transformer cannot determine whether the current flowing through the self-extinguishing element is the current flowing through the diode.

On the other hand, when the load motor consumes energy in the driving direction, the mode is such that current flows only through the diode. In this mode, no current flows even if the self-extinguishing element is ignited.

Even in such a mode in which no current flows through the self-extinguishing element, when an overcurrent is detected, the protection circuit operates to shut off the self-extinguishing element and stop the regenerative inverter.

In order to prevent such a situation, there is a method in which a current transformer is provided in the self-extinguishing element circuit to detect only the self-extinguishing element current, but generally, the self-extinguishing element of a converter having a regenerative inverter is provided. Since the diode and diode have a module structure of one package, the variable flow rate cannot be attached only to the circuit of the self-extinguishing element. In addition, the number of current transformers increases in order to attach the current transformer to each arm of the self-extinguishing element.

The present invention has been made in view of such conventional problems, and an object thereof is to provide a case where an overcurrent flows through a self-extinguishing element of a regenerative inverter section added to a converter. An object of the present invention is to provide a converter device in which a protection circuit of a regenerative inverter unit operates.

[0015]

In order to achieve the above object, the converter device according to the present invention is provided with a self-extinguishing circuit provided with an overcurrent protection circuit for detecting an overcurrent of an input line to protect the self-extinguishing element. In a converter device to which a regenerative inverter unit including an arc element is added, the direction of the input line current is detected, and the timing at which the current flows from the detection signal and the ON signal of the self-extinguishing element to the self-extinguishing element is determined. And a timing detection circuit for detecting and making the overcurrent protection circuit active or inactive.

[0016]

The function of the current direction detection circuit is the direction of the input line current, that is,
The direction of the AC instantaneous current is detected, and the timing of the current flowing through the arc extinguishing element is detected from the detection signal and the gate signal of the self-extinguishing element of the regenerative inverter unit. The current detected by the overcurrent protection circuit is the current of the input line and is not limited to the current flowing through the arc-extinguishing element, but if the overcurrent protection circuit is activated or deactivated at the timing detected by the timing detection circuit, it will be extinguished. Overcurrent protection becomes possible when current is flowing through the arc element.

[0017]

Embodiments of the present invention will be described with reference to FIG. 4 the diode D ₁₁ to D ₁₆ bridge circuit transistor Q ₂₁ converter regeneration inverter is added consisting to Q ₂₅ of inverter 5 connected to the converter 4, the motor driven by the inverter 5 6, 16
_{1 to} 16 ₃ are current transformers that detect the input line current of the converter 4.

Reference numeral 7 ₁ is a timing detection circuit for detecting the current flowing through the transistor Q ₂₁ or Q _{24. The} R-phase input line current is flowing in the direction of arrow A from the current detected by the current transformer 16 ₁ . On the condition that the current A direction detection circuit 8 for detecting the current, the current B direction detection circuit 9 for detecting that the input line current is flowing in the direction of the arrow B, and the ON signal of the transistor Q ₂₁ are input. An OR circuit AND ₁ that outputs the output of the current A direction detection circuit 8 and an OR circuit AND ₂ that outputs the output of the current B direction detection circuit 9 on condition that the ON signal of the transistor Q ₂₄ is input. , A
OR circuit OR ₁ for outputting the output of ND ₁ or AND ₂
It is composed of.

Reference numerals 7 ₂ and 7 ₃ denote current transformers 16 ₂ and 1 respectively.
A timing detection circuit for detecting that a regenerative current is flowing from the output of 6 ₃ to the transistor Q ₂₂ or Q ₂₅ and Q ₂₃ or Q ₂₆ , and has the same configuration as the timing detection circuit 7 ₁ .

Reference numeral 20 is an overcurrent detection circuit for detecting an overcurrent from the outputs of the current transformers 16 _{1 to} 16 ₃ , OR ₂ is a logical sum circuit for passing the outputs of the timing detection circuits 7 _{1 to} 7 ₃ , and AND ₃ is a logical sum. This is a logical product circuit that outputs an overcurrent detection signal from the overcurrent detection circuit 20 on condition that there is an input from the circuit OR ₂ .

Next, the operation of the embodiment circuit will be described. Regarding the timing detection circuit 7 ₁ , a current flows in the current transformer 16 ₁ in the direction of arrow A or B. When the current transformer 16 ₁ detects the current in the arrow A direction, the current A direction detection circuit 8 outputs it. At this time, the current flowing through the current transformer 16 ₁ flows from the transistor Q ₂₁ or the diode D ₁₄ . Therefore, if the logical product circuit AND ₁ takes the logical product of the ON signal of the transistor Q ₂₁ and the output of the current A direction detection circuit 8, the timing at which the regenerative current is flowing in the transistor Q ₂₁ can be detected.

When the current transformer 16 ₁ detects the current in the direction of arrow B, the current B direction detection circuit 9 outputs it.
At this time, the current flowing through the current transformer 16 ₁ flows through the diode D ₁₁ or the transistor Q ₂₄ . Therefore, AND circuit AND
By taking the logical product of the ON signal of the transistor Q ₂₄ and the output of the current direction B direction detection circuit 9 at ₂ , the timing when the regenerative current is flowing through the transistor Q ₂₄ can be detected.

Therefore, it can be detected by the timing detection circuit 7 ₁ that a current flows through the transistor Q ₁₁ or Q ₂₄ . Similarly, the timing detection circuits 7 ₂ and 7 ₃ connected to the current transformers 16 ₂ and 16 ₃ allow the transistor Q ₁₂ or Q ₃ to be connected.
It is possible to detect the timing when the current flows through ₂₅ and Q ₁₃ or Q ₂₆ . The timing detection signals of the timing detection circuits 7 _{1 to} 7 ₃ pass through the logical sum circuit OR ₂ and the logical product circuit AND ₃
To enter. Thus, the overcurrent detection circuit 20 if the output timing detection circuit 7 _{1-7 3} when outputting to detect an overcurrent, the overcurrent detection output is outputted from the AND circuit the AND _3.

[0024] Therefore, by stopping the gate signal of the transistor Q ₂₁ to Q ₂₆ of the regenerative inverter by the output of the AND circuit the AND _3, it is over-current protection of the regenerative inverter.

[0025]

Since the present invention is configured as described above, it has the following effects.

(1) Since the protection circuit operates only when an overcurrent flows in the self-extinguishing element of the regenerative inverter attached to the converter, it is not necessary to stop the device unnecessarily regardless of the current direction as in the conventional case. Therefore, the operating rate of the device is significantly improved.

(2) Even if the rectifying element of the converter and the self-extinguishing element have a package module structure, the overcurrent of the self-extinguishing element can be detected.

[Brief description of drawings]

FIG. 1 is a configuration explanatory diagram of an overcurrent detection circuit according to an embodiment.

FIG. 2 is an explanatory diagram of a configuration of a conventional converter device.

[Explanation of symbols]

4 ... converter 5 ... Inverter 6 ... motor 7 _{1-7 2} ... timing detection circuit 8 ... Current A direction detection circuit 9 ... current B direction detecting circuit 10 ... control circuit 20 ... overcurrent detection circuit D ₁₁ to D of the regenerative inverter ₁₃ ... diode (rectifying device) Q ₁₁ to Q ₂₆ ... transistor (self-turn-off elements)

Claims (1)

[Claims] 1. A converter device having an overcurrent protection circuit for detecting an overcurrent of an input line to protect the self-extinguishing device, to which a regenerative inverter unit composed of the self-extinguishing device is added, the input line comprising: A timing detection circuit that detects the direction of the current and detects the timing at which the current flows to the self-extinguishing element from the detection signal and the ON signal of the self-extinguishing element to activate or deactivate the overcurrent protection circuit. A converter device characterized by being provided.