JP2011061965A - Power conversion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power conversion device which can fully reduce the ripples of a voltage by using a small-capacity capacitor, even when the frequency of a voltage of AC power is low. <P>SOLUTION: The power conversion device includes a bipolar/semipolar power conversion circuit which converts bipolar AC power into semipolar power, and outputs the semipolar power and a smoothing capacitor which reduces the ripples of the voltage of the semipolar power, and the device also includes a higher-frequency circuit which increases the ripples contained in the voltage of the semipolar power outputted by the bipolar/semipolar power conversion circuit to a prescribed frequency, and outputs the voltage of the semipolar power to the smoothing capacitor. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a power conversion device that converts power output from a generator such as an alternator.

Conventionally, in an aircraft, a three-phase AC voltage output from an alternator (generator) rotated by an engine is converted into a DC voltage by a rectifier circuit, and the DC voltage is stepped down to a predetermined voltage by a switching shunt. Various voltages are generated by a DC / DC converter, and these voltages are supplied to various loads.
As an invention relating to the control of such a power supply voltage, the following Patent Document 1 discloses a switching type shunt capable of reducing the on-resistance of the control element and reducing the amount of heat generated by switching by configuring the shunt regulator in a switching type. A regulator is disclosed.

In Patent Document 2 below, a DC voltage generated by rectification from an AC voltage is boosted by a step-up chopper circuit, the boosted DC voltage is charged to a capacitor, and a large charging current is generated from the voltage of the capacitor by the step-down chopper circuit. A charging device is disclosed that charges a battery in a short time with this charging current.
In general, a smoothing capacitor is attached to the output side of the rectifier circuit as described in Patent Document 1 and Patent Document 2 below, and voltage ripple is reduced by the smoothing capacitor.

JP-A 63-209463 JP 2002-325368 A

  By the way, in the above prior art, a smoothing capacitor is attached to the output side of the rectifier circuit in order to reduce the ripple of the voltage after rectification. In an aircraft, the voltage after rectification increases during high-speed rotation of the alternator, and the ripple of the voltage after rectification also decreases due to the decrease in the frequency of the three-phase AC voltage during low-speed rotation of the alternator. It is necessary to use a capacitor having a capacity as a smoothing capacitor. However, in order to satisfy the high withstand voltage and large capacity with film capacitors that can be mounted on aircraft, the size of the film capacitors becomes large, so that such film capacitors are mounted in severely restricted applications such as aircraft. That is very difficult.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a power conversion device that can sufficiently reduce voltage ripple with a small-capacitance capacitor even when the frequency of the AC voltage is low. And

  In order to achieve the above object, in the present invention, as a first solving means related to a power conversion apparatus, bipolar / single that converts bipolar AC power to unipolar power and outputs the unipolar power. A power conversion device comprising a polarity power conversion circuit and a smoothing capacitor for reducing ripples in the voltage of the unipolar power, the voltage of the unipolar power output by the bipolar / unipolar power conversion circuit In this case, a means for increasing the ripple included in the signal to a predetermined frequency and providing a high frequency circuit for outputting the voltage of the unipolar power to the smoothing capacitor is employed.

  In the present invention, as a second solving means related to the power conversion device, in the first solving means, the high frequency circuit is the high frequency circuit, and the bipolar / unipolar power conversion circuit outputs the piece. When the frequency of the ripple included in the voltage of the polar power is lower than a predetermined threshold, the frequency of the ripple included in the voltage of the unipolar power is increased above the threshold, and the voltage of the unipolar power is increased. Is output to the smoothing capacitor.

  In the present invention, as the third solving means relating to the power converter, in the first or second solving means, a means is adopted in which the high frequency circuit is a DC chopper circuit.

  In the present invention, as a fourth solving means relating to the power converter, in the third solving means, a means is adopted in which the DC chopper circuit is a step-up chopper circuit.

  According to the present invention, a bipolar / unipolar power conversion circuit that converts a bipolar AC voltage into a unipolar voltage and outputs the unipolar voltage, and a smoothing capacitor that reduces ripple of the unipolar voltage, A high-frequency circuit for increasing a ripple contained in a unipolar voltage output from a bipolar / unipolar power converter circuit to a predetermined frequency and outputting the unipolar voltage to a smoothing capacitor It comprises.

  Thus, in the present invention, even when the frequency of the AC voltage is low, that is, when the ripple having a low frequency exists in the unipolar voltage output from the bipolar / unipolar power conversion circuit, the high frequency circuit Thus, the ripple frequency of the unipolar voltage can be increased, and therefore the ripple of the unipolar voltage can be sufficiently reduced even with a small-capacity smoothing capacitor.

It is a circuit diagram which shows the structure of the power converter device A which concerns on one Embodiment of this invention. The U-phase of the three-phase AC power input to the rectifier bridge circuit 1 when the MOSFET 23 is always turned OFF without causing the boost chopper circuit 2 of the power converter A according to the embodiment of the present invention to perform the boost operation. Waveform diagram of V-phase line voltage, waveform diagram of unipolar voltage V1 output from rectifying bridge circuit 1, waveform diagram of DC voltage V2 output from smoothing capacitor 3, and DC output from step-down chopper circuit 4 It is a wave form diagram of voltage V3. Waveform of U-phase to V-phase line voltage of 3-phase AC voltage input to rectifier bridge circuit 1 when boosting chopper circuit 2 of power converter A according to an embodiment of the present invention performs a boosting operation FIG. 4 is a waveform diagram of a unipolar voltage V1 output from the rectifying bridge circuit 1, a waveform diagram of a DC voltage V2 output from the smoothing capacitor 3, and a waveform diagram of the DC voltage V3 output from the step-down chopper circuit 4. .

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present embodiment relates to a power converter that converts power input from a generator such as an alternator.
First, the circuit configuration of the power converter A will be described with reference to FIG. FIG. 1 is a circuit diagram showing a configuration of a power conversion device A according to the present embodiment.

  The power converter A rectifies and steps down the three-phase AC power input from the alternator B by the rotation of the engine (not shown), and outputs DC power to the load C. As shown in FIG. A rectifier bridge circuit 1 (bipolar / unipolar power conversion circuit), a step-up chopper circuit 2 (high frequency circuit), a smoothing capacitor 3, and a step-down chopper circuit 4 are configured.

  The rectifier bridge circuit 1 converts the three-phase AC power input from the alternator B into a unipolar power voltage and outputs the power to the boost chopper circuit 2. As shown in FIG. Rectification diodes 11a to 11f and output terminals 12a and 12b corresponding to the AC power of the phase are provided.

  The rectifying diode 11a has a cathode terminal connected to the positive output terminal 12a and an anode terminal connected to the U-phase winding of the alternator B and the cathode terminal of the rectifying diode 11d.

The rectifier diode 11b has a cathode terminal connected to the positive output terminal 12a and an anode terminal connected to the V-phase winding of the alternator B and the cathode terminal of the rectifier diode 11e.
The rectifier diode 11c has a cathode terminal connected to the positive output terminal 12a, and an anode terminal connected to the W-phase winding of the alternator B and the cathode terminal of the rectifier diode 11f.

The rectifier diode 11d has a cathode terminal connected to the U-phase winding of the alternator B and the anode terminal of the rectifier diode 11a, and an anode terminal connected to the negative output terminal 12b.
The rectifying diode 11e has a cathode terminal connected to the V-phase winding of the alternator B and the anode terminal of the rectifying diode 11b, and an anode terminal connected to the negative output terminal 12b.

  The rectifying diode 11f has a cathode terminal connected to the W-phase winding of the alternator B and the anode terminal of the rectifying diode 11c, and an anode terminal connected to the negative output terminal 12b.

  The output terminals 12a and 12b are a pair of connection terminals for outputting unipolar power generated in the rectifying diodes 11a to 11f to the boost chopper circuit 2. The positive output terminal 12a is the boost chopper circuit 2. The negative output terminal 12b is connected to the input other end of the step-up chopper circuit 2.

  The step-up chopper circuit 2 boosts the unipolar power supplied from the rectifying bridge circuit 1 by the chopping operation and outputs it to the smoothing capacitor 3. The input terminals 21a and 21b, the reactor 22, the MOSFET 23, the diode 24, and the output Terminals 25a and 25b, a voltage sensor 26, and a step-up PWM controller 27 are provided.

The input terminals 21 a and 21 b are a pair of connection terminals for inputting unipolar power from the rectification bridge circuit 1, and the positive input terminal 21 a is connected to the positive output terminal 12 a of the rectification bridge circuit 1. The negative-side input terminal 21 b is connected to the negative-side output terminal 12 b of the rectifying bridge circuit 1.
The reactor 22 has one end connected to the positive input terminal 21 a and the other end connected to the drain terminal of the MOSFET 23 and the anode terminal of the diode 24.

In the MOSFET 23, the drain terminal is connected to the other end of the reactor 22 and the anode terminal of the diode 24, the source terminal is connected to the negative input terminal 21 b and the output terminal 25 b, and the gate terminal is connected to the boost PWM controller 27. Has been.
The diode 24 has an anode terminal connected to the other end of the reactor 22 and the drain terminal of the MOSFET 23, and a cathode terminal connected to the positive output terminal 25a.

  The output terminals 25a and 25b are a pair of connection terminals for outputting unipolar power boosted by the chopping operation to the smoothing capacitor 3. The positive output terminal 25a is connected to one end of the smoothing capacitor 3, and the negative electrode The output terminal 25b on the side is connected to the other end of the smoothing capacitor 3.

  The voltage sensor 26 is a sensor that detects a voltage of unipolar power input from the input terminals 21a and 21b. As shown in FIG. 1, one end is connected to the positive-side input terminal 21a and the other end is a negative electrode. Side input terminal 21b. Based on the detection result, the voltage sensor 26 outputs a detection signal Sv1 indicating the voltage of unipolar power input from the input terminals 21a and 21b to the boost PWM control unit 27.

  The step-up PWM control unit 27 includes an interface circuit that performs input / output of signals with the MOSFET 23, and causes the MOSFET 23 to repeatedly execute ON / OFF by PWM control based on the detection signal Sv1. In the step-up chopper circuit 2, the MOSFET 23 repeatedly performs ON / OFF, thereby stepping up the voltage of the unipolar power input from the rectifying bridge circuit 1. The step-up PWM control unit 27 may be a control circuit that performs control only by hardware such as a semiconductor device, or may be a central processing unit (CPU), a read only memory (ROM), and a random access memory (RAM). And a control circuit using software that performs control based on a control program stored in the ROM.

  The smoothing capacitor 3 is a small-capacity capacitor provided for the purpose of smoothing the voltage of the unipolar power output from the boost chopper circuit 2, that is, reducing the ripple of the voltage of the unipolar power. The output terminal 25a on the positive side of the chopper circuit 2 and one end on the input side of the step-down chopper circuit 4 are connected, and the other end is connected to the output terminal 25b on the negative side of the step-up chopper circuit 2 and the other end on the input side of the step-down chopper circuit 4. It is connected.

  The step-down chopper circuit 4 steps down DC power supplied from the smoothing capacitor 3 by a chopping operation and outputs it to a load C. Input terminals 41a and 41b, a MOSFET 42, a diode 43, a reactor 44, a capacitor 45, and an output terminal 46a and 46b and a step-down PWM controller 47 are provided.

The input terminals 41 a and 41 b are a pair of connection terminals for inputting DC power from the smoothing capacitor 3. The positive input terminal 41 a is connected to the positive output terminal 25 a of the step-up chopper circuit 2 and one end of the smoothing capacitor 3. The negative input terminal 41 b is connected to the negative output terminal 25 b of the step-up chopper circuit 2 and the other end of the smoothing capacitor 3.
In the MOSFET 42, the drain terminal is connected to the positive input terminal 41 a, the source terminal is connected to the cathode terminal of the diode 43 and one end of the reactor 44, and the gate terminal is connected to the step-down PWM control unit 47.

The diode 43 has an anode terminal connected to the negative input terminal 41 b, one terminal of the capacitor 45 and the negative output terminal 46 b, and a cathode terminal connected to the source terminal of the MOSFET 42 and one end of the reactor 44.
One end of the reactor 44 is connected to the source terminal of the MOSFET 42 and the cathode terminal of the diode 43, and the other end is connected to one end of the capacitor 45 and the output terminal 46 a on the positive electrode side.
The capacitor 45 is provided for the purpose of smoothing the voltage of the DC power output to the load C, that is, reducing the ripple of the voltage of the DC power, and has one end connected to the other end of the reactor 44 and the positive side. The other end is connected to the output terminal 46a, and the other end is connected to the negative input terminal 41b, the anode terminal of the diode 43, and the negative output terminal 46b.

  The output terminals 46a and 46b are a pair of connection terminals for outputting the voltage of the DC power stepped down by the chopping operation to the load C. The output terminal 46a on the positive side is connected to one end on the input side of the load C. The negative output terminal 46b is connected to the other end of the load C on the input side.

  The step-down PWM control unit 47 includes an interface circuit that performs input / output of signals with the MOSFET 42, and causes the MOSFET 42 to repeatedly execute ON / OFF by PWM control. In the step-down chopper circuit 4, the voltage of the DC power input from the smoothing capacitor 3 is stepped down by the MOSFET 42 repeatedly executing ON / OFF. Note that the step-down PWM control unit 47 may be a control circuit that performs control only by hardware such as a semiconductor device, or includes a CPU, a ROM, and a RAM, and is based on a control program stored in the ROM. A control circuit using software that performs control may be used.

Next, operation | movement of the power converter device A which concerns on this embodiment comprised in this way is demonstrated in detail.
When the engine starts rotating, the alternator B starts outputting three-phase AC power. Then, the U-phase to V-phase line voltage and frequency increase in proportion to the engine speed. That is, the voltage and frequency of the AC power output from the alternator B are in a proportional relationship.

In the power converter A, the rectifying bridge circuit 1 converts the three-phase AC power input from the alternator B into unipolar power, and outputs the unipolar power to the boost chopper circuit 2.
In the step-up chopper circuit 2, when unipolar power is input from the input terminals 21a and 21b, the voltage sensor 26 outputs a detection signal Sv1 to the step-up PWM control unit 27.

  The step-up PWM control unit 27 determines whether or not the unipolar voltage input from the rectifying bridge circuit 1 exceeds the threshold value based on the detection signal Sv1. The step-up PWM control unit 27 causes the MOSFET 23 to perform a chopping operation when the unipolar voltage input from the rectifying bridge circuit 1 does not exceed the threshold value, thereby outputting the output from the output terminals 25a and 25. Match the polarity voltage to the threshold.

As described above, in the step-up chopper circuit 2, when the step-up PWM control unit 27 does not exceed the threshold value of the unipolar voltage input from the rectifying bridge circuit 1, that is, the ripple included in the unipolar voltage is reduced. When the frequency is lower than the frequency corresponding to the threshold voltage, by causing the MOSFET 23 to perform a chopping operation, the unipolar voltage is boosted to the threshold value, and the ripple included in the unipolar voltage is adjusted according to the chopping operation. Increase to the desired frequency. The chopping frequency of the step-up chopper circuit 2 is about 100 times higher than the frequency of the unipolar voltage that does not exceed the threshold value.
Thereby, it is possible to suppress a unipolar voltage having a low ripple frequency from being supplied from the rectifying bridge circuit 1 to the smoothing capacitor 3.

The operation result of the power converter A will be described in detail with reference to FIGS. 2 and 3.
FIG. 2 shows the U-phase of the three-phase AC power input to the rectifier bridge circuit 1 when the MOSFET 23 is always turned OFF without causing the boost chopper circuit 2 of the power conversion device A according to this embodiment to perform the boost operation. -Waveform diagram of V-phase line voltage, waveform diagram of unipolar voltage V1 output from rectifier bridge circuit 1, waveform diagram of DC voltage V2 output from smoothing capacitor 3, and step-down chopper circuit 4 output It is a wave form diagram of DC voltage V3. 2A shows the waveform of the voltage between the U-phase and V-phase lines of the three-phase AC power input to the rectification bridge circuit 1, and FIG. 2B shows the output of the rectification bridge circuit 1. 2C shows the waveform of the DC voltage V2 output from the smoothing capacitor 3, and FIG. 2D shows the waveform of the DC voltage V3 output from the step-down chopper circuit 4. The waveform is shown.

  FIG. 3 shows the U-phase to V-phase line voltage of the three-phase AC power input to the rectifier bridge circuit 1 when the boost chopper circuit 2 of the power conversion device A according to the present embodiment performs the boost operation. Waveform diagram, waveform diagram of unipolar voltage V1 output from rectifier bridge circuit 1, waveform diagram of DC voltage V2 output from smoothing capacitor 3, and waveform diagram of DC voltage V3 output from step-down chopper circuit 4. is there. 3A shows the waveform of the U-phase to V-phase voltage of the three-phase AC power input to the rectifying bridge circuit 1, and FIG. 3B shows the output from the rectifying bridge circuit 1. 3C shows the waveform of the DC voltage V2 output from the smoothing capacitor 3, and FIG. 3D shows the waveform of the DC voltage V3 output from the step-down chopper circuit 4. The waveform is shown. 2 and 3, the vertical axis represents voltage (V), and the horizontal axis represents time. In FIG. 2 and FIG. 3, Va, Va ′, Vb, Vd, and Vd ′ are reference values for comparing FIG. 2 with FIG.

  In the power conversion device A, when the MOSFET 23 is always turned off without causing the boost chopper circuit 2 to perform the boost operation, as shown in FIGS. 2B and 2C, the rectifier bridge circuit 1 outputs a piece. The waveforms of the polarity voltage V1 and the DC voltage V2 output from the smoothing capacitor 3 are the same. Therefore, in the low frequency range of the U-phase to V-phase line voltage shown in FIG. 2A, the ripple frequency of the unipolar voltage V1 and the DC voltage V2 is also low. When the frequency of the ripple of the DC voltage V2 is low, the small-capacity smoothing capacitor 3 cannot sufficiently reduce the ripple of the DC voltage V2. Therefore, as shown in FIG. Ripple remains in the DC voltage V3 output from the circuit 4.

  However, in the power converter A, when the boost chopper circuit 2 performs the boosting operation, the unipolar voltage V1 is set in the low-frequency range of the U-phase-V-phase line voltage shown in FIG. The existing ripple is sufficiently reduced at the DC voltage V2. This is because the ripple is sufficiently reduced by the smoothing capacitor 3 when the boost chopper circuit 2 increases the frequency of the ripple of the unipolar voltage V1. Thereby, as shown in FIG.3 (d), the ripple of DC voltage V3 which the step-down chopper circuit 4 outputs is fully reduced.

  As described above, in the power conversion device A according to the present embodiment, the boost chopper circuit 2 increases the ripple included in the unipolar voltage V1 output from the rectifying bridge circuit 1 to a predetermined frequency. Thereby, in the power converter A, when the frequency of the voltage of the three-phase AC power output from the alternator B is low, that is, the unipolar voltage V1 output from the rectifying bridge circuit 1 has a low-frequency ripple. Even in this case, since the boost chopper circuit 2 can increase the frequency of the ripple of the unipolar voltage V1, even the small-capacity smoothing capacitor 3 can sufficiently generate the ripple of the unipolar voltage V1. Can be reduced.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the power conversion device A according to the above embodiment, the boost chopper circuit 2 increases the frequency of the ripple included in the unipolar voltage V1 output from the rectifying bridge circuit 1, but the present invention is limited to this. Not.

For example, instead of the step-up chopper circuit 2, a step-down chopper circuit may be mounted in front of the smoothing capacitor 3, and the step-down chopper circuit may increase the ripple frequency of the unipolar voltage output from the rectifier bridge circuit 1. Good.
Further, the unipolar voltage V1 output from the rectifying bridge circuit 1 is inverted and a phase-shifted voltage is generated, and the voltage is superimposed on the unipolar voltage V1, thereby increasing the ripple frequency. .

(2) In the power conversion device A according to the above embodiment, the rectifying bridge circuit 1 converts the bipolar AC power into the unipolar power, and the boost chopper circuit 2 chops the voltage of the power. The present invention is not limited to this.
For example, one diode may convert bipolar AC power into unipolar power, and the boost chopper circuit 2 may chop the unipolar power. That is, the bipolar / unipolar power conversion circuit of the present invention is not limited to the rectifying bridge circuit.

A ... Power converter, B ... Alternator, C ... Load, 1 ... Rectifier bridge circuit, 2 ... Boost chopper circuit, 3 ... Smoothing capacitor, 4 ... Step-down chopper circuit, 11 ... Rectifier bridge circuit, 11a-11f ... Rectification Diode, 12a, 12b ... Output terminal, 21a, 21b ... Input terminal, 22 ... Reactor, 23 ... MOSFET, 24 ... Diode, 25a, 25b ... Output terminal, 26 ... Voltage sensor, 27 ... Boost PWM control unit, 41a, 41b ... input terminal, 42 ... MOSFET, 43 ... diode, 44 ... reactor, 45 ... capacitor, 46a, 46b ... output terminal, 47 ... step-down PWM controller

Claims (4)

A bipolar / unipolar power conversion circuit for converting bipolar AC power into unipolar power and outputting the unipolar power, and a smoothing capacitor for reducing ripples in the voltage of the unipolar power. A power converter,
A high frequency circuit is provided that raises a ripple contained in the unipolar power voltage output from the bipolar / unipolar power conversion circuit to a predetermined frequency and outputs the unipolar power voltage to the smoothing capacitor. The power converter characterized by the above-mentioned.   The high frequency circuit converts the unipolar power voltage into a unipolar power voltage when a ripple frequency included in the unipolar power voltage output from the bipolar / unipolar power converter circuit is lower than a predetermined threshold. 2. The power converter according to claim 1, wherein the frequency of the included ripple is increased above the threshold value, and the voltage of the unipolar power is output to the smoothing capacitor.   The power converter according to claim 1, wherein the high frequency circuit is a direct current chopper circuit. The power converter according to claim 3, wherein the DC chopper circuit is a step-up chopper circuit.

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