JP3240032B2 - Control method of boost type three-phase full-wave rectifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method of a boost type three-phase full-wave rectifier which supplies a boosted DC output voltage to a load by switching a switching semiconductor element connected in a three-phase bridge configuration at a high frequency. About.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional apparatus which receives three-phase AC input power and supplies a DC voltage higher than the three-phase AC voltage to a load. Referring to FIG. 3, the conventional apparatus will be described. 1U, 1V, 1W are three-phase AC input terminals for receiving three-phase AC power, 2U, 2V, 2W, respectively.
Is a phase line connected to each of the three-phase AC input terminals 1U, 1V, 1W, 3 is a circuit breaker connected to these phase lines, 4 is a current transformer 4 for detecting a current flowing through each phase line.
Current detector consisting of U, 4V, 4W, etc., 5U, 5V,
5W is a boost inductor connected to each of the phase lines 2U, 2V, 2W, C1, C2, and C3 are capacitors connected between the phase lines, and 6 is an I connected to a three-phase bridge.
Switching semiconductor devices Q1, Q2, Q3, Q4, Q5, Q6 such as GBTs or transistors or bipolar electrostatic induction transistors (B-SIT), and diodes D1, provided in anti-parallel to each of them.
A three-phase full-wave rectifier circuit including D2, D3, D4, D5, and D6; 7, a smoothing capacitor; 8, a load; 9, a control circuit for switching the switching semiconductor elements Q1 to Q6 according to a predetermined sequence; Reference numeral 10 denotes a drive circuit that supplies drive signals a to f to the switching semiconductor elements Q1 to Q6 according to a control signal from the control circuit 9.

The operation of the switching semiconductor devices Q1 to Q6 will be described below in brief. The switching semiconductor devices Q1 to Q6 have a frequency sufficiently higher than the frequency of the three-phase AC input, for example, 25k exceeding the audible sound range.
The pulse width control, that is, the duty ratio control, is performed in Hz. In these switching semiconductor elements Q1 to Q6, the three switching semiconductor elements of each phase are turned on at the same time, and the off point is controlled depending on the current flowing through each phase line 2U, 2V, 2W and the DC output voltage. For example, drive circuit 1
Assuming that an on-drive signal is applied to switching semiconductor elements Q2, Q3, and Q6 from 0, the U-phase input current flows from phase line 2U to boosting inductor 5U → switching semiconductor element Q2 → smoothing capacitor 7 → switching semiconductor element Q3 → step-up. 5V → phase line 2V,
The W-phase input current flows from the phase line 2W to the boost inductor 5W.
→ Switching semiconductor element Q6 → Smoothing capacitor 7 →
Switching semiconductor device Q3 → Step-up inductor 5V →
Flow to phase line 2V. The V-phase input current is the sum of the U-phase input current and the W-phase input current. As described above, when energy is stored in the boost inductor, the output voltage is also applied, so that energy is circulated. The current flowing through each phase line is controlled to be a sine wave whose phase matches each phase voltage.

When the U-phase input current reaches its reference value, the switching semiconductor element Q2 is turned off.
The current flows through the step-up inductor 5U → the diode D1 → the switching semiconductor element Q3 → the step-up inductor 5V → the phase line 2V → the phase line 2U, and the energy supply source becomes only the input voltage, but the energy is still accumulated. Also, when the W-phase input current reaches its reference value,
The switching semiconductor element Q6 is turned off, but the current is increased by the step-up inductor 5W → diode D5 → switching semiconductor element Q3 → step-up inductor 5V → phase line 2
V → flows to the phase line 2W, and the energy supply source is only the input voltage, but the energy is still stored. . Furthermore, when the V-phase input current reaches its reference value, switching semiconductor element Q3 is turned off, and if switching semiconductor element Q2 or Q6 is already off, the energy stored in boost inductors 5V, 5U, and 5W. Is the phase line 2V from the step-up inductor 5V → phase line 2U (or 2W) → step-up inductor 5U (or 5W) → diode D1 (or D5) → smoothing capacitor 7 or load 8 → diode D4 → step-up inductor 5
It flows to V and is released to the load side.

As described above, when the switching semiconductor element Q3 is turned off, if the switching semiconductor element Q2 or Q6 has already been turned off, the energy stored in the boost inductors 5V, 5U and 5W is discharged to the load side. However, for example, if the switching semiconductor element Q2 is still on when the switching semiconductor element Q3 is turned off, the current flows from the step-up inductor 5V to the phase line 2V → the phase line 2U → the step-up inductor 5U.
→ Switching semiconductor device Q2 → Diode D4, and the energy supply source is only the input voltage, but the energy storage mode continues.

Next, assuming that the circuit breaker 3 is opened due to an accident or the like and the phase lines 2U, 2V, 2W are instantaneously cut off, the phase lines 2U, 2V, 2W are disconnected from the three-phase AC input power supply side. The boost inductors 5U, 5
The current flowing through V and 5W naturally flows through capacitors C1, C2 and C3 connected between the respective phase lines, and these capacitors are charged. If these capacitors are not connected, a high voltage will be generated.

[0007]

However, such a conventional apparatus and control method have the following problems. (1) Capacitors C1, C2 and C3 having relatively large capacitance must be provided in consideration of the case where the circuit breaker opens. (2) The current flowing through each boost inductor 5U, 5V, 5W is substantially the same as the current flowing through each phase line, becomes a sine wave whose phase matches each phase voltage, and the peak value increases. 5U, 5V, 5W increase in size. (3) When energy is stored in the step-up inductors 5U, 5V, and 5W, a circulating current flows from the load side to the input side, so that there is a disadvantage that power loss is large.

An object of the present invention is to solve such conventional problems and reduce the switching loss of the switching semiconductor element, the power loss of the boosting inductor, and the power loss due to the circulating current.

[0009]

According to the first aspect of the present invention, there is provided a circuit breaker capable of interrupting three-phase AC power and detecting a phase current flowing through each of the phase lines. A current detector, a boost inductor provided in each phase line, a three-phase full-wave rectifier circuit including a switching semiconductor element connected in a three-phase bridge configuration, a smoothing capacitor,
A control circuit for performing high-frequency switching of the switching semiconductor element in a predetermined sequence; and a phase line between the circuit breaker and each of the step-up inductors as inputs, the positive and negative of the three-phase full-wave rectifier circuit. In the control method of the step-up type three-phase full-wave rectifier provided with the three-phase bridge circuit having the common line as an output, the switching semiconductor element of each phase is set to be approximately 2/1/2 of a half cycle (π period) of each phase voltage.
3 is controlled so as to perform the high-frequency switching operation for a period equal to 3, and one cycle (2π) of each phase voltage π / 3 to 2π /
It is an object of the present invention to provide a method of controlling a step-up type three-phase full-wave rectifier that controls so as to stop during periods of 3 and 4π / 3 to 5π / 3.

[0010]

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. The same symbols as those shown in FIG. 3 indicate the corresponding members. First, the newly added three-phase bridge circuit 11 has six diodes D7, D8, D9, D10,
D11, D12, and diodes D7, D9, D1
One anode is connected to the phase lines 2U, 2V, 2W, respectively, and the cathode is connected to the positive common line 6A of the three-phase full-wave rectifier circuit 6. Also, diodes D8, D10,
The cathodes of D12 are phase lines 2U, 2V, 2W, respectively.
, And the anode is connected to the negative common line 6B of the three-phase full-wave rectifier circuit 6.

Next, the control circuit 9 will be described. The error amplifier 9A outputs an error signal obtained by amplifying the voltage between both ends of the smoothing capacitor 7, that is, the difference between the DC output voltage and the reference value. The inter-phase voltage-phase voltage converter 9B converts each inter-phase voltage into a corresponding phase voltage signal. The U-phase voltage is
As shown in FIGS. 2 (a) and 2 (d), the U-V
It becomes a sine wave voltage delayed by degrees. As shown in FIGS. 2 (b) and 2 (e) and FIGS. 2 (c) and 2 (f), the V-phase voltage signal and the W-phase voltage signal also delay the V-W phase voltage and the W-U phase voltage by 30 degrees. Sine wave voltage. Each phase voltage signal from the inter-phase voltage-phase voltage converter 9B is multiplied by the error signal from the error amplifier 9A in the multiplier 9C and sent to the pause setting / logic circuit 9D.

The reference pulse generator 9E generates a reference pulse for determining when to turn on the switching semiconductor devices Q1 to Q6 of the three-phase full-wave rectifier circuit 6. The frequency of the reference pulse is, for example, 25 kHz. The comparison circuit 9F compares each current detection signal corresponding to the current flowing through each phase line from the current detection circuit 4 with a signal of each phase from the multiplier 9C,
Switching semiconductor elements Q1-Q of three-phase full-wave rectifier circuit 6
6, and a signal having a controlled on-pulse width is given to the pause setting / logic circuit 9D. The pause setting / logic circuit 9D supplies the drive circuit 10 with a control signal for turning on and off the switching semiconductor elements Q1 to Q6 according to a predetermined sequence.

On the other hand, the pause setting / logic circuit 9D receives each phase voltage signal from the inter-phase voltage-phase voltage converter 9B and receives each phase voltage in each period of 0 to π and π to 2π in one cycle of each phase voltage. Of the switching semiconductor elements are sequentially stopped by ず つ, that is, the control signal is not transmitted from the control circuit 9 to the driving circuit 10 during that interval, and only two of the three phases of the switching semiconductor elements perform the switching operation. Is controlled so as to perform In the preferred embodiment, the pause setting / logic circuit 9D is configured to output π / 3 to 2π / 3 in the period 0 to π of one cycle of each phase voltage, and 4π / 3 to 5π / in the period π to 2π.
In the section 3, that is, the 60-degree section on both sides of the peak of each phase voltage, the switching semiconductor elements of each phase are sequentially stopped, and the duty ratio control is performed in the other sections.

Next, the operation of this circuit for one cycle T will be described. First, a brief description will be given of driving signals a, b, c, d, e, and f of a frequency sufficiently higher than the frequency of a three-phase AC input (50/60 Hz), for example, 25 kHz.
In each of the controllable periods shown at the high level in FIGS. 2G to 2L, the driving circuit 10 applies the voltage to the control terminals of the switching semiconductor devices Q1 to Q6. Therefore, the switching semiconductor elements Q1 to Q6 are as shown in FIG.
The switching operation is performed at a high frequency in each of the controllable periods indicated by high levels (1) to (1). In this example,
When each phase voltage has a positive polarity, the switching semiconductor element Q2,
The phase voltages corresponding to Q4 and Q6 are approximately 0 to 60 degrees and 12 degrees.
Perform high-frequency switching operation in the range of 0 to 180 degrees,
When each phase voltage has a negative polarity, the switching semiconductor element Q
1, Q3 and Q5 correspond to approximately 180 to 240 of the corresponding phase voltage.
And a high frequency switching operation is performed in the range of 300 degrees to 360 degrees. Therefore, the switching semiconductor elements Q1 to Q1
Q6 suspends the high-frequency switching operation at approximately 30 degrees on both sides about the peak value of the phase voltage. Immediately before time t0, the values of the currents flowing through the boost inductors 4U, 4V, and 4W of each phase are zero, -I, and + I, respectively.
The current of each phase is controlled so as to be in phase with the voltage of each phase as in the related art.

At time t0, switching semiconductor elements Q2,
When Q6 starts high-frequency operation, the U-phase input current flows from the phase line 2U to the boost inductor 5U → the switching semiconductor element Q2 → the diode D4 → the boost inductor 5V → the phase line 2V, and from the phase line 2U to the boost inductor 5U. → The switching semiconductor element Q2 → the diode D10 → flows to the phase line 2V and increases. Further, the W-phase input current flows from the phase line 2W to the boost inductor 5W → the switching semiconductor element Q6 → the diode D4 → the boost inductor 5V → the phase line 2V.
The current flows from W to the boost inductor 5W → the switching semiconductor element Q6 → the diode D10 → the phase line 2W. At this time, since the boost inductor 5V is short-circuited by the diodes D10 and D4, the current value is held at -I. The V-phase input current is the sum of the U-phase input current and the W-phase input current.

When the U-phase input current reaches the reference value determined by the multiplier 9C, the switching semiconductor element Q2 is turned off, and the energy stored in the boost inductor 5U is transferred from the phase line 2U to the boost inductor 5U to the diode. D1 → smoothing capacitor 7 or load 8 → diode D4 → step-up inductor 5V → phase line 2V → phase line 2U, and step-up inductor 5U → diode D1 → smoothing capacitor 7 or load 8 → diode D
10 → phase line 2V → flows to phase line 2U, and is discharged to the load side and decreases.

Next, when the W-phase input current reaches the reference value, the switching semiconductor element Q6 is turned off, and the energy stored in the boost inductor 5W is converted into the boost inductor 5W → the diode D5 → the smoothing capacitor 7 or the load 8
→ diode D4 → step-up inductor 5V → phase line 2
V → phase line 2W and boost inductor 5
W → diode D5 → smoothing capacitor 7 or load 8 →
The current flows through the diode D10 → the phase line 2V → the phase line 2W, and is discharged to the load side and decreases. Thereafter, the switching operation is performed in this operation mode until time t1, the U-phase current increases sinusoidally, and the W-phase current decreases sinusoidally.

As shown in FIG. 2, at time t1, the U-phase current becomes I, the V-phase current becomes -I, the W-phase current becomes zero, and the switching semiconductor elements Q3 and Q5 start high frequency switching operation. The V-phase input current flows from the phase line 2U to the step-up inductor 5U → diode D1 → switching semiconductor element Q3 → step-up inductor 5V → phase line 2V, and from the phase line 2U to the diode D7 → switching semiconductor element Q3 → step-up inductor 5V. → Phase line 2V
Flow and increase. The W-phase input current is 2U
From the step-up inductor 5U → the diode D1 → the switching semiconductor element Q5 → the step-up inductor 5W → the phase line 2W, and from the phase line 2U to the diode D7.
→ Switching semiconductor device Q5 → Boost inductor 5W
→ It flows to the phase line 2W and increases. At this time, since the boost inductor 5U is short-circuited by the diodes D7 and D1, the current value is held at I. The U-phase input current is the sum of the V-phase input current and the W-phase input current.

When the V-phase input current reaches the reference value determined by the multiplier 9C, the switching semiconductor element Q3 is turned off, and the energy stored in the boost inductor 5V is changed to the boost inductor 5V → phase line 2V → phase Line 2
U → step-up inductor 5U → diode D1 → smoothing capacitor 7 or load 8 → flow through diode D4 and step-up inductor 5V → phase line 2V → phase line 2
U → diode D7 → smoothing capacitor 7 or load 8 →
The current flows to the diode D4, and is discharged to the load side and decreases. When the W-phase input current reaches the reference value, the switching semiconductor element Q5 is turned off, and the energy stored in the boost inductor 5W is changed to the boost inductor 5W.
→ Phase line 2W → Phase line 2U → Boost inductor 5U
→ Diode D1 → Smoothing capacitor 7 or load 8 → Step up inductor 5W while flowing to diode D6 →
The phase line 2W → the phase line 2U → the diode D7 → the smoothing capacitor 7 or the load 8 → the diode D6, and is discharged to the load side and decreases. Thereafter, the switching operation is performed in this operation mode until time t2, the V-phase current increases sinusoidally, and the W-phase current decreases sinusoidally.

At time t2, the U-phase current becomes zero, the V-phase current becomes zero, the W-phase current becomes -I, and the switching semiconductor element Q
2. Q4 starts the high frequency switching operation. The U-phase input current flows from the phase line 2U to the step-up inductor 5U → the switching semiconductor element Q2 → the diode D6 → the step-up inductor 5W → the phase line 2W.
The current flows from U to the step-up inductor 5U → the switching semiconductor element Q2 → the diode D12 → the phase line 2W, and increases. Also, the V-phase input current flows from the phase line 2V to the boost inductor 5V → the switching semiconductor element Q4 → the diode D6 → the boost inductor 5W → the phase line 2W, and from the phase line 2V to the boost inductor 5V → the switching semiconductor element Q4 → Diode D12 → phase line 2
Flows to W and increases. At this time, the boost inductor 5W
Is short-circuited by the diodes D12 and D6, the current value is kept at -I. W-phase input current is equal to U-phase input current and V
This is the sum with the phase input current.

When the U-phase input current reaches the reference value determined by the multiplier 9C, the switching semiconductor element Q2 is turned off, and the energy stored in the boosting inductor 5U is converted into the boosting inductor 5U → diode D1 → smoothing. Capacitor 7 or load 8 → diode D6 → step-up inductor 5W → phase line 2W → phase line 2U, and at the same time, step-up inductor 5U → diode D1 → smoothing capacitor 7 or load 8 → diode D12 → phase line 2
W → flows to the phase line 2U, and is discharged to the load side and decreases. When the V-phase input current reaches the reference value, the switching semiconductor element Q4 is turned off, and the energy stored in the boost inductor 5V is changed to the boost inductor 5V.
V → diode D3 → smoothing capacitor 7 or load 8 →
Diode D6 → Step-up inductor 5W → Phase line 2W
→ While flowing to phase line 2V, booster inductor 5V
→ Diode D3 → smoothing capacitor 7 or load 8 → diode D12 → phase line 2W → phase line 2V,
It is released to the load side and decreases. Thereafter, the switching operation is performed in this operation mode until time t3, the U-phase current decreases sinusoidally, and the V-phase current increases sinusoidally.

At time t3, the U-phase current becomes zero, the V-phase current becomes I, the W-phase current becomes -I, and the switching semiconductor element Q
1, Q5 starts high frequency switching operation. The U-phase input current flows from the phase line 2V to the boost inductor 5V → the diode D3 → the switching semiconductor device Q1 → the boost inductor 5U → the phase line 2U, and the phase line 2
From V, diode D9 → switching semiconductor element Q1 →
The boost inductor 5U flows to the phase line 2U and increases. Also, the W-phase input current flows from the phase line 2V to the boost inductor 5V → the diode D3 → the switching semiconductor element Q5 → the boost inductor 5W → the phase line 2W, and from the phase line 2V to the diode D9 → the switching semiconductor element Q5 → the boost Inductor 5W → phase line 2W
Flow and increase. At this time, since the boost inductor 5V is short-circuited by the diodes D9 and D3, the current value becomes I
Is held. The V-phase input current is the sum of the U-phase input current and the W-phase input current.

When the U-phase input current reaches the reference value determined by the multiplier 9C, the switching semiconductor element Q1 is turned off, and the energy stored in the boost inductor 5U is converted into the boost inductor 5U → phase line 2U → phase Line 2
V → step-up inductor 5V → diode D3 → smoothing capacitor 7 or load 8 → flow through diode D2 and step-up inductor 5U → phase line 2U → phase line 2
V → diode D9 → smoothing capacitor 7 or load 8 →
The current flows to the diode D2, and is discharged to the load side and decreases. When the W-phase input current reaches the reference value, the switching semiconductor element Q5 is turned off, and the energy stored in the boost inductor 5W is changed to the boost inductor 5W.
→ Phase line 2W → Phase line 2V → Boost inductor 5V
→ Diode D3 → Smoothing capacitor 7 or load 8 → Step up inductor 5W while flowing to diode D6 →
The current flows through the phase line 2W → the phase line 2V → the diode D9 → the smoothing capacitor 7 or the load 8 → the diode D6, and is discharged to the load side and decreases. Thereafter, the switching operation is performed in this operation mode until time t4, the U-phase current decreases sinusoidally, and the W-phase current increases sinusoidally.

At time t4, the U-phase current becomes -I, the V-phase current becomes I, the W-phase current becomes zero, and the switching semiconductor element Q
4. Q6 starts the high frequency switching operation. The V-phase input current flows from the phase line 2V to the step-up inductor 5V → the switching semiconductor element Q4 → the diode D2 → the step-up inductor 5U → the phase line 2U.
From V, it flows to the boost inductor 5V → the switching semiconductor element Q4 → the diode D8 → the phase line 2U and increases. Also, the W-phase input current flows from the phase line 2W to the boost inductor 5W → the switching semiconductor element Q6 → the diode D2 → the boost inductor 5U → the phase line 2U, and from the phase line 2W to the boost inductor 5W → the switching semiconductor element Q6 → Diode D8 → phase line 2U
Flow and increase. At this time, since the boost inductor 5U is short-circuited by the diodes D8 and D2, the current value becomes −
I is held. The U-phase input current is the sum of the V-phase input current and the W-phase input current.

When the V-phase input current reaches the reference value determined by the multiplier 9C, the switching semiconductor element Q4 is turned off, and the energy stored in the boosting inductor 5V is changed to the boosting inductor 5V → the diode D3 → the smoothing. Capacitor 7 or load 8 → diode D2 → step-up inductor 5U → phase line 2U → phase line 2V, and step-up inductor 5V → diode D3 → smoothing capacitor 7 or load 8 → diode D8 → phase line 2U
→ It flows to the phase line 2V and is discharged to the load side and decreases. When the W-phase input current reaches the reference value, switching semiconductor element Q6 is turned off, and the energy stored in boost inductor 5W becomes boost inductor 5W.
→ diode D5 → smoothing capacitor 7 or load 8 → diode D2 → step-up inductor 5U → phase line 2U →
While flowing to the phase line 2W, the boost inductor 5W →
The current flows from the diode D5 → the smoothing capacitor 7 or the load 8 → the diode D8 → the phase line 2U → the phase line 2W, and is discharged to the load side and decreases. Thereafter, the switching operation is performed in this operation mode until time t5, the V-phase current decreases sinusoidally, and the W-phase current increases sinusoidally.

At time t5, the U-phase current becomes -I, the V-phase current becomes zero, the W-phase current becomes I, and the switching semiconductor element Q
1, Q3 starts high frequency switching operation. The U-phase input current flows from the phase line 2W to the step-up inductor 5W → the diode D5 → the switching semiconductor device Q1 → the step-up inductor 5U → the phase line 2U, and the phase line 2U.
From W to diode D11 → switching semiconductor element Q1
→ Step-up inductor 5U → Phase line 2U flows and increases. Also, the V-phase input current flows from the phase line 2W to the boost inductor 5W → the diode D5 → the switching semiconductor element Q3 → the boost inductor 5V → the phase line 2V, and from the phase line 2W to the diode D11 → the switching semiconductor element Q3 → the boost. Inductor 5V → Phase line 2
Flow to V and increase. At this time, the boost inductor 5W
Is short-circuited by the diodes D11 and D5, the current value is held at I. The W-phase input current is the sum of the U-phase input current and the V-phase input current.

When the U-phase input current reaches the reference value determined by the multiplier 9C, the switching semiconductor element Q1 is turned off, and the energy stored in the boosting inductor 5U is changed to the boosting inductor 5U → phase line 2U → phase Line 2
W → step-up inductor 5W → diode D5 → smoothing capacitor 7 or load 8 → flow through diode D2 and step-up inductor 5U → phase line 2U → phase line 2
W → diode D11 → smoothing capacitor 7 or load 8
→ It flows to the diode D2 and is discharged to the load side and decreases. When the V-phase input current reaches the reference value, the switching semiconductor element Q3 is turned off, and the energy stored in the boost inductor 5V is changed to the boost inductor 5V.
V → phase line 2V → phase line 2W → step-up inductor 5
W → diode D5 → smoothing capacitor 7 or load 8 →
While flowing through the diode D4, the step-up inductor 5V
→ phase line 2V → phase line 2W → diode D11 → smoothing capacitor 7 or load 8 → diode D4,
It is released to the load side and decreases. Thereafter, the switching operation is performed in this operation mode until time t6, the U-phase current increases sinusoidally, and the V-phase current decreases sinusoidally.

As can be seen from the above description, according to the present invention, the phase line 2 between the circuit breaker 3 and each boost inductor 5 and the positive and negative common lines 6 of the three-phase full-wave rectifier circuit 6
Since diodes D7 to D12 are provided between A and 6B so as to form a three-phase bridge configuration, all the phase currents flow through each boost inductor 5 in the conventional device.
In this embodiment, the phase current is divided into two, and a part thereof flows through the corresponding diodes D7 to D12 during the idle period of each switching semiconductor element, and therefore, the current flowing through the corresponding boost inductor 5 becomes the diodes D7 to D12.
Therefore, it is easily understood that each boost inductor 5 reduces power loss including iron loss.

In the control method of the preferred embodiment,
Since the switching semiconductor devices Q1 to Q6 suspend the high-frequency switching operation by about 30 degrees on both sides around the peak value of the phase voltage, the current flowing through each boost inductor 5 is in the range of about 60 to 120 degrees and 240 to 300 degrees. And the power loss including the iron loss is further improved, and at the same time, the switching semiconductor devices Q1 to Q6
Halts around the peak value of the flowing current, so that the switching power loss can be further reduced. Further, in this embodiment, although the switching semiconductor elements Q1 to Q6 are stopped, the current of each phase becomes substantially a sine wave and the power factor becomes a value close to 1 as described above. There is no danger of causing.

Further, diodes D7 to D12 are provided so as to form a three-phase bridge configuration as described above, and each of switching semiconductor elements Q1 to Q6 has approximately 2π / of a half period (π) of the corresponding phase voltage. The high-frequency switching is performed only in the period of 3 and the other period of approximately π / 3 is stopped. That is, in any section of one cycle of the frequency of the input voltage, only the appropriate two-phase switching semiconductor element of the three phases is switched at a high frequency, so that when energy is stored in the boost inductor 5,
In the case of the conventional control method, a circulating current flowing from the output side to the three-phase AC input power supply side caused a large power loss in the circuit. Since the circulating current returning to the phase AC input power supply does not flow, the power loss of the circuit can be reduced.

Even if the circuit breaker 3 is cut off due to a failure or the like during operation, the boosting inductor 5 is clamped to the output voltage by the newly added diodes D7 to D12. Occurrence can be prevented.

In the embodiment described above, when MOSFETs are used as the switching semiconductor elements Q1 to Q6, the body diodes of the respective MOSFETs can be used without separately connecting the diodes D1 to D6. .

[0039]

As described above, according to the present invention, it is not necessary to provide a capacitor on the input side for preventing a high voltage from being generated when the circuit breaker is opened, and it is not necessary to provide a capacitor for each boost inductor. It is possible to reduce the hysteresis loss, the switching power loss of the switching semiconductor element of each phase, and the power loss of the circuit.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an embodiment of the present invention.

FIG. 2 is a diagram showing waveforms of respective units for explaining an embodiment of the present invention.

FIG. 3 is a diagram for explaining a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Three-phase alternating current input power supply 9A ... Error amplifier 2 ... Phase line 9B ... Interphase voltage-phase voltage converter 3 ... Circuit breaker 9C ... Multiplier 4 ... Current Detection circuit 9D: Rest setting / logic circuit 5: Step-up inductor 9E: Reference pulse generator 6: Three-phase full-wave rectifier 9F: Comparison circuit 7: Smoothing capacitor 10. ... Drive circuit 8 ... Load 11 ... 3-phase bridge circuit 9 ... Control circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-115836 (JP, A) JP-A-63-89069 (JP, A) JP-A-60-109770 (JP, A) JP-A-60-1985 229677 (JP, A) JP-A-4-58785 (JP, A) JP-A-60-9383 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02M 7/219

Claims (1)

(57) [Claims] 1. A circuit breaker capable of interrupting three-phase AC power,
A current detector for detecting a phase current flowing through each of the phase lines, a boost inductor provided for each phase line, and a switching semiconductor element connected in a three-phase bridge configuration;
A phase full-wave rectifier circuit, a smoothing capacitor, a control circuit for performing high-frequency switching of the switching semiconductor element in a predetermined sequence, and the phase line between the circuit breaker and each of the boosting inductors as inputs, Outputs the positive and negative common lines of the three-phase full-wave rectifier circuit.
In the control method of the step-up type three-phase full-wave rectifier provided with the phase bridge circuit, the switching semiconductor element of each phase performs a high-frequency switching operation for a period substantially equal to ２ of a half cycle (π period) of each phase voltage. Control in one cycle of each phase voltage (2
(3) a control method for controlling a step-up three-phase full-wave rectifier, wherein the control is performed so as to stop during periods of π / 3 to 2π / 3 and 4π / 3 to 5π / 3.