JPH0631384U - Forward converter - Google Patents

Abstract

(57) [Summary] [Purpose] A single-phase or three-phase input is used to output the specified voltage. [Structure] The output of the three-phase full-wave rectifier 1'is set to the step-up chopper 2
In the forward converter that outputs the voltage to the load through the load amplifier, the deviation between the voltage setting value V _DC set and the voltage detection value V _DC det is amplified by the voltage amplifier 13, and the multiplier 14 ′ outputs the voltage amplifier output and the rectifier 1 ′. The detected voltage value Vdet is multiplied to form a current command Iset proportional to this waveform, the current command Iset is compared with the hysteresis comparator 15 ′ and the output current detected value Idet of the rectifier 1 ′, and the voltage is boosted via the gate circuit 16. The gate of the switching element of the chopper is controlled so that the rectifier output current matches the rectifier output voltage waveform and the output voltage to the load is maintained at the set level.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a single-phase / three-phase input forward conversion device.

[0002]

[Prior art]

 Conventionally, in a single-phase input forward converter, there is a method of detecting the input voltage and current and using a step-up chopper to change the input current to a power factor of 1 and make the current waveform a sine wave. An example of this is shown in FIG.

In FIG. 4, 1 is a single-phase full-wave rectifier, 2 is a step-up chopper composed of a DC reactor DCL ₁ connected to the rectifier, a diode D ₁ , a switching element TR ₁ and a DC capacitor C ₁ . A load connected to the boost chopper.

Reference numeral 11 is a voltage detector (DC / DC converter) for detecting the output voltage of the step-up chopper, 13 is a voltage amplifier for amplifying the deviation between the set voltage V _DC set and the detected voltage V _DC det, and 14 is an input voltage. A multiplier for multiplying the detected voltage Vdet from the voltage transformer PT ₁ for detecting the current command Iset and outputting the current command Iset; 15 is a current detector CT ₂ for detecting the current command Iset and the input current The current comparator Idet is compared, and when the current detection value is less than the current command value, the gate of the switching element TR ₁ of the step-up chopper 2 is turned on. When the current detection value is more than the current command value, the gate is turned off. Hysteresis comparator , 16 are gate circuits provided between the hysteresis comparator 15 and the gate of the switching element TR ₁ .

However, according to this forward conversion device, the output voltage V _DC is controlled to be equal to the voltage setting V _DC set by feedback, and the input is made by comparing the current command Iset with the detection current Idet. The current is controlled so that it has the same phase and waveform as the input voltage, that is, a sine wave with a power factor of 1.

[0006]

[Problems to be solved by the device]

 In the above-mentioned forward conversion device, when a single-phase full-wave rectifier is used as a three-phase full-wave rectifier so that the input phase number mode can be used in single phase or three phases, control can be performed in the case of single phase, but three phase Can't be controlled.

Therefore, when the input phase number mode is the single phase, the power factor is 1, the input current waveform sine wave control is performed, and when the input phase number mode is the three phases, the control is not performed.

Therefore, a circuit for determining whether the input is single-phase or three-phase is required, and there is a drawback that the DC voltage is different between the single-phase and the three-phase and the load is adversely affected.

The present invention has been made in view of the above problems of the related art, and an object thereof is to provide a forward conversion device capable of outputting a voltage as set by a single-phase or three-phase input. To do.

[0010]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the forward converter in the present invention is a forward converter in which a boost chopper for controlling the output voltage is connected to a three-phase full-wave rectifier, the set value of the output voltage and the detected value of the output voltage. , A multiplier that outputs the rectifier output current command proportional to the rectifier output power waveform by multiplying the output voltage of this voltage amplifier by the detected value of the rectifier output voltage, and this current It is provided with a hysteresis comparator that compares the command and the detected value of the output current of the rectifier and outputs the gate signal of the switching element of the boost chopper.

[0011]

[Action]

 Since the voltage amplifier amplifies the deviation between the set value of the output voltage and the detected value of the output voltage, the output voltage of this voltage amplifier and the detected value of the output current of the rectifier are proportional to the rectifier output voltage waveform from the multiplier. The rectifier output current command is output.

The hysteresis comparator compares this current command with the detected value of the output current of the rectifier. When the detected current value is smaller than the current command, the switching element of the boost chopper is turned on, and when it is larger, it is turned off. Is output to boost the voltage and control it.

Therefore, the load voltage is controlled by the feedback system of the voltage amplifier to the voltage of the voltage setting level regardless of whether the input of the rectifier is single-phase or three-phase, and the rectifier output current is proportional to the rectifier output voltage waveform. It is controlled to be the same as the command.

Therefore, when the input of the rectifier is single-phase, the rectifier output voltage is a single-phase full-wave rectified wave, so that the power factor is 1 and the input current is a sine wave. In the case of three-phase, the rectifier output voltage is a three-phase full-wave rectified wave, so it is equivalently a square wave with a large DC reactor.

[0015]

【Example】

 An embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the same components as those shown in FIG. 4 of the related art will be designated by the same reference numerals and redundant description will be omitted.

In FIG. 1, 1'is a three-phase full-wave rectifier, CT ₁ is a current detector that detects the rectifier output current, 12 is a voltage detector that detects the output voltage of the rectifier 1 ', and 14' is a voltage detector. A multiplier that multiplies the voltage detection Vdet from the output device 12 and the output of the voltage amplifier 13 to output the current command Iset.

Reference numeral 15 ′ is a hysteresis comparator which compares the current command Iset with the current detection I _DC set from the current detector CT ₁ and outputs it to the gate circuit 16. Others are the same as those in FIG.

With the above configuration, when the input phase number mode of the rectifier 1'is a single phase, the voltage detection Vdet from the DC / DC converter 12 is a single phase as shown in FIG. It becomes a full-wave rectified wave, and in the case of three-phase, it becomes a three-phase full-wave rectified wave as shown in Fig. 2B.

However, when the input phase number mode is a single phase, the current command Iset from the multiplier 14 'is proportional to the voltage detection waveform of FIG. This current command Iset and the detected current Idet from the current detector CT ₁ are compared by the hysteresis comparator 15 ′, and the gate of the switching element TR ₁ is controlled via the gate circuit 16 as shown in FIG.

Since the current command Iset is proportional to the voltage amplifier output that amplifies the deviation between the voltage setting value V _DC set and the voltage detection value V _DC det of the load voltage, the step-up chopper so that the detection current Idet becomes equal to the current command Iset. Control 2 Therefore, the input current of the forward converter 1'becomes a sine wave having the same phase as the voltage, and the load voltage becomes the voltage setting level.

When the input phase number mode is three-phase, the current command Iset from the multiplier 14 ′ is proportional to the voltage waveform shown in FIG. The current command Iset and the detected current Idet are compared by the hysteresis comparator 15 ′, and the gate of the switching element TR ₁ is controlled via the gate circuit 16.

Therefore, the output voltage is controlled to the set level and the detection current Idet is controlled so as to change like the waveform of the detection voltage Vdet. However, the input current in this case is equivalent to a large direct current. It becomes a square wave with a reactor.

[0023]

[Effect of device]

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

(1) A forward converter capable of controlling the output voltage to a set level with single-phase and three-phase inputs can be obtained.

(2) When the input current is single-phase, it becomes a sine wave current with a power factor of 1, and when it is three-phase, it becomes a square wave current with a large DC reactor, so the effective value of the input current becomes small and the input power decreases. Is reduced.

(3) Since the conversion efficiency is improved, the diode of the forward converter and the DC reactor of the boost chopper can be downsized.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

2A and 2B are waveform diagrams of forward converter output voltage detection at single-phase input and three-phase input.

FIG. 3 is an explanatory diagram of control operation.

FIG. 4 is a circuit diagram showing a conventional example.

[Explanation of symbols]

1,1 '... Rectifier 2 ... boost chopper 11, 12 ... voltage detector (DC / DC converter) 13 ... voltage amplifier 14, 14' ... multipliers 15, 15 '... hysteresis comparator 16 ... gate circuit CT _1, CT ₂ … Current detector

Claims (1)

[Scope of utility model registration request] 1. A forward conversion device comprising a three-phase full-wave rectifier and a step-up chopper for controlling the output voltage, the voltage amplifier amplifying a deviation between a set value of the output voltage and a detected value of the output voltage, and the voltage amplifier. Compare the current command and the detected value of the rectifier output current with a multiplier that multiplies the output voltage of the amplifier and the detected value of the rectifier output voltage to output the rectifier output current command that is proportional to the rectifier output power waveform. A forward conversion device that is equipped with a hysteresis comparator that outputs the gate signal of the switching element of the step-up chopper, and that allows the output voltage to reach the set level regardless of whether the rectifier input is single-phase or three-phase.