JPH07308069A - Boosting type three-phase full-wave rectifier and its control method - Google Patents

Abstract

PURPOSE:To reduce the size of a boosting type three-phase full-wave rectifier, by so providing a three-phase bridge circuit comprising diodes that as its AC input lines respective phase lines present respectively between a circuit breaker and respective boosting inductors are used and as its DC output lines positive and negative common lines of a three-phase full-wave rectifying circuit are used, and by reducing the switching losses, the power losses of the boosting inductors and the power losses caused by circulating currents of the boosting type rectifier. CONSTITUTION:A three-phase bridge circuit 11 comprising diodes D7-D12 is so provided that as its input lines phase lines 2U, 2V, 2W present respectively between a circuit breaker 3 and respective boosting inductors 5U, 5V, 5W are used and as its DC output lines positive and negative common lines 6A, 6B of a three-phase full-wave rectifying circuit 6 are used. Therefore, respective phase currents are divided respectively into respective two ones, and in the pauses of respective switching semiconductor elements Q1-Q6, the one-parts of the phase currents flow respectively through the corresponding diodes D7-D12. As a result, the currents flowing through the corresponding boosting inductors 5U, 5V, 5W are clamped respectively by the diodes D7-D12, and are made nearly flat. Thereby, the capacitors for preventing the generations of high voltages when the circuit breaker 3 is opened are not required to be provided on the input side of a boosting type three-phase full-wave rectifier, and as a result, the various losses of the rectifier can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boosting type three-phase full-wave rectifying device for controlling a switching semiconductor element connected in a three-phase bridge structure to a load and supplying a boosted DC output voltage to a load and its control. Regarding the method.

[0002]

2. Description of the Related Art A conventional device shown in FIG. 3 receives a three-phase AC input power and supplies a DC voltage higher than the three-phase AC voltage to a load. A conventional device will be described with reference to FIG. 3. 1U, 1V and 1W are three-phase AC input terminals for receiving three-phase AC power, 2U, 2V and 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, and 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 boosting inductor connected to each of the phase lines 2U, 2V, 2W, C1, C2, C3 are capacitors connected between the phase lines, and 6 is an I connected to a three-phase bridge.
A switching semiconductor element Q1, Q2, Q3, Q4, Q5, Q6 such as a GBT, a transistor, or a bipolar static induction transistor (B-SIT), and a diode D1, provided in anti-parallel with each of them.
A three-phase full-wave rectifier circuit including D2, D3, D4, D5, and D6, 7 is a smoothing capacitor, 8 is a load, and 9 is a control circuit that causes the switching semiconductor elements Q1 to Q6 to perform a switching operation according to a predetermined sequence, Reference numeral 10 is a drive circuit that supplies drive signals a to f to the switching semiconductor elements Q1 to Q6 in accordance with a control signal from the control circuit 9.

The operation will be briefly described below. The switching semiconductor elements Q1 to Q6 have a frequency sufficiently higher than the frequency of the three-phase AC input, for example, 25 k beyond the audible sound range.
The pulse width is controlled in Hz, that is, the duty ratio is controlled. In these switching semiconductor elements Q1 to Q6, the three switching semiconductor elements of each phase are simultaneously turned on, and the off time is controlled depending on the currents flowing through the phase lines 2U, 2V, 2W and the DC output voltage. For example, drive circuit 1
If an ON drive signal is given to the switching semiconductor elements Q2, Q3, Q6 from 0, the U-phase input current is increased from the phase line 2U to the inductor 5U for boosting → the switching semiconductor element Q2 → the smoothing capacitor 7 → the switching semiconductor element Q3 → boosting. Inductor 5V → Phase line 2V,
W-phase input current from phase line 2W to boost inductor 5W
→ Switching semiconductor element Q6 → Smoothing capacitor 7 →
Switching semiconductor element Q3 → Boost inductor 5V →
It flows to the phase line 2V. Further, the V-phase input current is the sum of the U-phase input current and the W-phase input current. In this way, when energy is stored in the boost inductor, the output voltage is also applied, so energy circulation occurs. The current flowing through each phase line is controlled to be a sine wave whose phase matches the phase voltage.

When the U-phase input current reaches its reference value, the switching semiconductor element Q2 turns off.
The current flows through the boosting inductor 5U → diode D1 → switching semiconductor element Q3 → boosting inductor 5V → phase line 2V → phase line 2U, and the energy supply source is 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 turns off, but the current is boosted inductor 5W → diode D5 → switching semiconductor element Q3 → boost inductor 5V → phase line 2
It flows to the V → phase line 2W, and the energy supply source is only the input voltage, but the accumulation of energy is still continued. . Furthermore, when the V-phase input current reaches its reference value, the switching semiconductor element Q3 is turned off, and if the switching semiconductor element Q2 or Q6 has already been turned off, the energy stored in the boosting inductors 5V, 5U, 5W. Is from the boosting inductor 5V to the phase line 2V → the phase line 2U (or 2W) → the boosting inductor 5U (or 5W) → the diode D1 (or D5) → the smoothing capacitor 7 or the load 8 → the diode D4 → the boosting inductor 5
It flows to V and is discharged 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 boosting inductors 5V, 5U, 5W is released to the load side. However, for example, if the switching semiconductor element Q2 is still turned on when the switching semiconductor element Q3 is turned off, the current flows from the step-up inductor 5V to the phase line 2V → phase line 2U → step-up inductor 5U.
→ Switching semiconductor device Q2 → It flows into diode D4, and the energy supply source is only the input voltage, but the energy storage mode still continues.

Next, if the circuit breaker 3 is opened to instantly interrupt the phase lines 2U, 2V, 2W due to an accident or the like, the phase lines 2U, 2V, 2W are disconnected from the 3-phase AC input power source side. Therefore, the boost inductors 5U, 5
The current flowing through V and 5 W naturally flows through capacitors C1, C2 and C3 connected between the phase lines, and these capacitors are charged. If these capacitors are not connected, 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 a relatively large capacitance must be provided in consideration of the case where the circuit breaker opens. (2) The currents flowing through the boosting inductors 5U, 5V, and 5W are substantially the same as the currents flowing through the phase lines, and have a sine wave whose phase matches the phase voltage, and the peak value becomes large. The size of 5U, 5V, and 5W will increase. (3) When energy is stored in the boosting inductors 5U, 5V, 5W, a circulating current returning from the load side to the input side flows, resulting in a large power loss.

The present invention is mainly intended to solve such conventional problems, to 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, and to downsize the device. Has an aim.

[0009]

In order to solve the above-mentioned problems, the present invention detects a phase current flowing through each of a circuit breaker capable of interrupting three-phase AC power and a phase line. Current detector, boosting inductor provided in each phase line, three-phase full-wave rectifier circuit in which switching semiconductor elements are connected in a three-phase bridge configuration, smoothing capacitor,
And a step-up three-phase full-wave rectifier having a control circuit for high-frequency switching the switching semiconductor element in a predetermined sequence, wherein the phase line between the circuit breaker and each of the step-up inductors is used as an input. ，
A step-up type three-phase full-wave rectifying device, to which is connected a three-phase bridge circuit that outputs the positive and negative common lines of the three-phase full-wave rectifying circuit.

In order to solve the above-mentioned problems, the control circuit according to a second aspect of the present invention includes a pause circuit for suspending the switching operation of the switching semiconductor element for a predetermined period in a predetermined sequence. A step-up type three-phase full-wave rectifier according to claim 1 is provided.

According to a third aspect of the present invention, in order to solve the above-mentioned problems, a diode is connected in antiparallel to the switching semiconductor element, and the step-up type according to the first or second aspect. A three-phase full-wave rectifier is provided.

In order to solve the above-mentioned problems, the present invention according to a fourth aspect comprises a three-phase bridge in which a boosting inductor and a switching semiconductor element are provided in each of phase lines for supplying three-phase AC power to a load side. In a control method of a step-up type three-phase full-wave rectifier having a three-phase full-wave rectifier circuit connected in a configuration and a control circuit for high-frequency switching the switching semiconductor element in a predetermined sequence, each phase line A diode in which a part of energy storage and discharge of the connected boosting inductor is connected between the phase line and the positive and negative common lines of the three-phase full-wave rectifier circuit in a three-phase bridge configuration. The present invention provides a method for controlling a boosting type three-phase full-wave rectifier, which is characterized in that it is controlled so as to flow through it.

In order to solve the above-mentioned problems, the present invention provides a booster inductor and a switching semiconductor element, which are provided in each phase line for supplying three-phase AC power to the load side, with a three-phase bridge. A method of controlling a step-up three-phase full-wave rectifier, comprising: a three-phase full-wave rectifier circuit connected in a configuration; and a control circuit for high-frequency switching the switching semiconductor element in a predetermined sequence. In any section in each cycle, only the appropriate two-phase switching semiconductor elements of the three phases are subjected to high-frequency switching operation, and when energy is stored in the boost inductor connected to each phase line, from the load side. A control method for a boost type three-phase full-wave rectifier characterized by controlling a circulating current not to flow to an input side. That.

According to a sixth aspect of the present invention, in order to solve the above problems, the switching semiconductor element of each phase is subjected to high frequency switching for a period equal to approximately 2/3 of a half cycle (π period) of each phase voltage. It is intended to provide a control method of a step-up type three-phase full-wave rectifier, which is operated and controlled so as to be stopped for the remaining period.

According to a seventh aspect of the present invention, in order to solve the above-mentioned problems, a high frequency switching operation of the switching semiconductor element is performed for one cycle of each phase voltage so that the switching loss of the switching semiconductor element is reduced. Two
7. The boosting according to claim 5 or claim 6, wherein the boosting is performed during periods of π / 3 to 2π / 3 and 4π / 3 to 5π / 3 of π), and is controlled in a period other than the rest period. A method for controlling a three-phase full-wave rectifier is provided.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. The same symbols as those shown in FIG. 3 indicate corresponding members. First, the newly added three-phase bridge circuit 11 includes six diodes D7, D8, D9, D10,
D11, D12, diodes D7, D9, D1
The anode of No. 1 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, the 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.

Explaining the control circuit 9, the error amplifier 9A outputs an error signal obtained by amplifying the voltage across the smoothing capacitor 7, that is, the difference between the DC output voltage and the reference value. The interphase voltage-phase voltage converter 9B converts each interphase voltage into a corresponding phase voltage signal. U phase voltage is
As shown in FIGS. 2 (a) and 2 (d), the U-V phase voltage is set to 30
The sine wave voltage is delayed by 4 degrees. As shown in FIGS. 2 (b) and (e), and FIGS. 2 (c) and (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, respectively. It becomes the sine wave voltage. Each phase voltage signal from the interphase voltage-phase voltage converter 9B is multiplied by the error signal from the error amplifier 9A in the multiplier 9C, and is sent to the pause setting / logic circuit 9D.

The reference pulse generator 9E generates a reference pulse that determines the on-time points of the switching semiconductor elements 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 each phase signal from the multiplier 9C,
Switching semiconductor elements Q1 to Q of the three-phase full-wave rectifier circuit 6
The turn-off time point of 6 is determined, and a signal having a controlled on-pulse width is given to the pause setting / logic circuit 9D. The pause setting / logic circuit 9D gives the drive circuit 10 a control signal for turning on / off the switching semiconductor elements Q1 to Q6 in accordance with a predetermined sequence.

On the other hand, the pause setting / logic circuit 9D receives each phase voltage signal from the interphase voltage-phase voltage converter 9B, and in each period of 0 to π and π to 2π of one cycle of each phase voltage, each phase. The switching semiconductor elements are sequentially stopped by ⅓, that is, the control signal is prohibited from being sent from the control circuit 9 to the driving circuit 10 only in that section, and only the switching semiconductor elements of two phases of the three phases perform the switching operation. Control to do. Further, in the preferred embodiment, the pause setting / logic circuit 9D is π / 3 to 2π / 3 in the 0 to π period of one cycle of each phase voltage, and 4π / 3 to 5π / in the π to 2π period.
3, the switching semiconductor element of each phase is sequentially stopped in a 60 degree section on both sides of the peak of each phase voltage, and duty ratio control is performed in the other sections.

Next, the operation of one cycle T in this circuit will be described. First, the outline thereof will be described. The drive signals a, b, c, d, e, f having a frequency sufficiently higher than the frequency (50/60 Hz) of the three-phase AC input, for example, 25 kHz are
In each controllable period shown by the high level in FIGS. 2G to 2L, the voltage is applied from the drive circuit 10 to the control terminals of the switching semiconductor elements Q1 to Q6. Therefore, the switching semiconductor elements Q1 to Q6 are shown in FIG.
The switching operation is performed at high frequency in each controllable period indicated by the high level of (1) to (l). In this example,
When each phase voltage has a positive polarity, switching semiconductor element Q2,
Approximately 0 to 60 degrees and 12 of the phase voltage corresponding to Q4 and Q6
Performs high frequency switching operation in the range of 0 to 180 degrees,
When the voltage of each phase is negative, the switching semiconductor element Q
1, Q3, Q5 correspond to approximately 180-240 of the phase voltage
And high frequency switching operation is performed in the range of 300 to 360 degrees. Therefore, the switching semiconductor elements Q1 to Q1
Q6 suspends the high frequency switching operation on both sides around the peak value of the phase voltage by about 30 degrees. Immediately before time t0, the values of the currents flowing through the boosting inductors 4U, 4V, and 4W of the respective phases are zero, -I, and + I, respectively.
The current of each phase is controlled to have the same phase as the voltage of each phase, as in the conventional case.

At time t0, the switching semiconductor element 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 at the same time, from the phase line 2U to the boost inductor 5U. -> Switching semiconductor element Q2-> diode D10-> phase line 2V increases. In addition, the W-phase input current flows from the phase line 2W to the step-up inductor 5W → the switching semiconductor element Q6 → the diode D4 → the step-up inductor 5V → the phase line 2V, and
The current flows from W to the boosting inductor 5W → switching semiconductor element Q6 → diode D10 → phase line 2W. At this time, the boosting inductor 5V is short-circuited by the diodes D10 and D4, so that 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 boosting inductor 5U is phase line 2U → boosting inductor 5U → diode. D1 → smoothing capacitor 7 or load 8 → diode D4 → boosting inductor 5V → phase line 2V → phase line 2U, and at the same time, boosting inductor 5U → diode D1 → smoothing capacitor 7 or load 8 → diode D
10 → Phase line 2V → Phase line 2U flows 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 boosting inductor 5W is boosted by the boosting inductor 5W → diode D5 → smoothing capacitor 7 or load 8.
→ diode D4 → boost 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 from the diode D10 to the phase line 2V to the phase line 2W, 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 boosting inductor 5U → the diode D1 → the switching semiconductor element Q3 → the boosting inductor 5V → the phase line 2V, and also from the phase line 2U to the diode D7 → the switching semiconductor element Q3 → the boosting inductor 5V. → Phase line 2V
Flow to and increase. Also, the W-phase input current is the phase line 2U
From the boosting inductor 5U to the diode D1 to the switching semiconductor element Q5 to the boosting inductor 5W to the phase line 2W, and from the phase line 2U to the diode D7.
→ Switching semiconductor element Q5 → Boost inductor 5W
→ Flow to phase line 2W and increase. At this time, the boosting inductor 5U is short-circuited by the diodes D7 and D1, so that 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 boosting inductor 5V is boosted by the boosting inductor 5V → phase line 2V → phase. Line 2
U → Boosting inductor 5U → Diode D1 → Smoothing capacitor 7 or load 8 → Diode D4 and boosting inductor 5V → Phase line 2V → Phase line 2
U → diode D7 → smoothing capacitor 7 or load 8 →
It flows into the diode D4, 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 boosting inductor 5W is transferred to the boosting inductor 5W.
→ phase line 2W → phase line 2U → boost inductor 5U
→ diode D1 → smoothing capacitor 7 or load 8 → diode D6 and boost inductor 5W →
Phase line 2W-> phase line 2U-> diode D7-> smoothing capacitor 7 or load 8-> diode D6 flows 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 is I, the V-phase current is zero, the W-phase current is -I, and the switching semiconductor element Q
2, Q4 starts 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, and at the same time, the phase line 2
The current flows from U to the step-up inductor 5U → switching semiconductor element Q2 → diode D12 → phase line 2W and increases. Further, the V-phase input current flows from the phase line 2V to the boosting inductor 5V → the switching semiconductor element Q4 → the diode D6 → the boosting inductor 5W → the phase line 2W, and also from the phase line 2V to the boosting inductor 5V → the switching semiconductor element Q4 → Diode D12 → phase line 2
Flow to W and increase. At this time, boost inductor 5W
Is short-circuited by the diodes D12 and D6, the current value is held at -I. W-phase input current is the same as U-phase input current and V
It is the sum of 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 boosted by the boosting inductor 5U → diode D1 → smoothing. Capacitor 7 or load 8 → diode D6 → boosting inductor 5W → phase line 2W → phase line 2U, and at the same time boosting inductor 5U → diode D1 → smoothing capacitor 7 or load 8 → diode D12 → phase line 2
W → flows to the phase line 2U, 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 stored in the boost inductor 5V.
V → diode D3 → smoothing capacitor 7 or load 8 →
Diode D6 → Boost inductor 5W → Phase line 2W
→ Current flowing to phase line 2V and boost 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 step-up inductor 5V → the diode D3 → the switching semiconductor element Q1 → the step-up inductor 5U → the phase line 2U and the phase line 2V.
V to diode D9 → switching semiconductor element Q1 →
It flows from the boosting inductor 5U to the phase line 2U and increases. Further, the W-phase input current flows from the phase line 2V to the boosting inductor 5V → diode D3 → switching semiconductor element Q5 → boosting inductor 5W → phase line 2W, and also from the phase line 2V to diode D9 → switching semiconductor element Q5 → boosting. Inductor 5W → Phase line 2W
Flow to and increase. At this time, since the boosting inductor 5V is short-circuited by the diodes D9 and D3, the current value is I
Held in. 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 boosted by the boost inductor 5U → phase line 2U → phase. Line 2
V → Boost inductor 5V → Diode D3 → Smoothing capacitor 7 or load 8 → Diode D2, and boost inductor 5U → Phase line 2U → Phase line 2
V → diode D9 → smoothing capacitor 7 or load 8 →
It flows into the diode D2, 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 boosting inductor 5W is transferred to the boosting inductor 5W.
→ Phase line 2W → Phase line 2V → Boost inductor 5V
→ diode D3 → smoothing capacitor 7 or load 8 → diode D6 and boost inductor 5W →
Phase line 2W → phase line 2V → diode D9 → smoothing capacitor 7 or load 8 → diode D6 flows, 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 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 and the phase line 2V.
The voltage flows from V to the step-up inductor 5V → switching semiconductor element Q4 → diode D8 → phase line 2U 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 D2 → the boost inductor 5U → the phase line 2U, and at the same time, from the phase line 2W to the boost inductor 5W → the switching semiconductor element Q6 → Diode D8 → phase line 2U
Flow to and increase. At this time, the boosting inductor 5U is short-circuited by the diodes D8 and D2, so that 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 Q4 is turned off, and the energy stored in the boosting inductor 5V becomes the boosting inductor 5V → diode D3 → smoothing. Capacitor 7 or load 8 → diode D2 → boosting inductor 5U → phase line 2U → phase line 2V, and at the same time, boosting inductor 5V → diode D3 → smoothing capacitor 7 or load 8 → diode D8 → phase line 2U
→ It flows to the phase line 2V, is discharged to the load side and decreases. 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 stored in the boost inductor 5W.
→ diode D5 → smoothing capacitor 7 or load 8 → diode D2 → boosting inductor 5U → phase line 2U →
It flows into the phase line 2W and the boost inductor 5W →
The current flows from the diode D5 to the smoothing capacitor 7 or the load 8 to the diode D8 to the phase line 2U to 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 element Q1 → the step-up inductor 5U → the phase line 2U and the phase line 2W.
From W to diode D11 → switching semiconductor element Q1
→ Step-up inductor 5U → Flows to phase line 2U and increases. Further, the V-phase input current flows from the phase line 2W to the boosting inductor 5W → diode D5 → switching semiconductor element Q3 → boosting inductor 5V → phase line 2V, and also from the phase line 2W to diode D11 → switching semiconductor element Q3 → boosting. Inductor 5V → Phase line 2
Flow to V and increase. At this time, 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 boost inductor 5U is boosted by the boost inductor 5U → phase line 2U → phase. Line 2
W → Boost inductor 5W → Diode D5 → Smoothing capacitor 7 or load 8 → Diode D2, and boost inductor 5U → Phase line 2U → Phase line 2
W → diode D11 → smoothing capacitor 7 or load 8
→ It flows to the diode D2, 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 stored in the boost inductor 5V.
V → Phase line 2V → Phase line 2W → Boost inductor 5
W → diode D5 → smoothing capacitor 7 or load 8 →
It flows to the diode D4 and the boost 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 understood from the above description, in the present invention, the phase line 2 between the circuit breaker 3 and each boosting inductor 5 and the positive and negative common lines 6 of the three-phase full-wave rectification circuit 6 are provided.
Since diodes D7 to D12 are provided between A and 6B so as to form a three-phase bridge configuration, in the conventional device, all the phase currents flow through the boosting inductors 5.
In this embodiment, the phase current is divided into two, and a part of the phase current flows through the corresponding diodes D7 to D12 during the idle period of each switching semiconductor element, so that the current flowing through the corresponding boosting inductor 5 is the diodes D7 to D12.
It is easily understood that each boosting inductor 5 reduces power loss including iron loss because it is clamped by and becomes almost flat.

Particularly, in the control method of the above-mentioned preferred embodiment,
Since the switching semiconductor elements Q1 to Q6 suspend the high frequency switching operation for about 30 degrees on both sides of the peak value of the phase voltage, the current flowing through each boosting inductor 5 is in the range of about 60 to 120 degrees and 240 to 300 degrees. Becomes almost flat, and the reduction of the power loss including iron loss is further improved, and at the same time, the switching semiconductor elements Q1 to Q6.
Since it stops near the peak value of the flowing current, the switching power loss can be further reduced. Further, in this embodiment, although the switching semiconductor elements Q1 to Q6 are stopped, the currents of the respective phases are substantially sinusoidal and the power factor is close to 1 as described above. There is no danger of causing.

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

Further, 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.

When MOSFETs are used as the switching semiconductor elements Q1 to Q6 in the above-described embodiments, the body diode of each MOSFET 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 the booster inductor It is possible to reduce hysteresis loss, switching power loss of the switching semiconductor element of each phase, and power loss of the circuit.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a waveform of each part for explaining an embodiment of the present invention.

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

[Explanation of symbols]

1 ... 3-phase AC input power supply 9A ... Error amplifier 2 ... Phase line 9B ... Phase-to-phase voltage-phase voltage converter 3 ... Circuit breaker 9C ... Multiplier 4 ... Current Detection circuit 9D: pause setting / logic circuit 5 ... boosting 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

Claims (7)

[Claims] 1. A circuit breaker capable of interrupting three-phase AC power,
A current detector for detecting a phase current flowing through each phase line, a boosting inductor provided in each phase line, and a switching semiconductor element are connected in a three-phase bridge configuration.
A booster type three-phase full-wave rectifier device comprising a phase full-wave rectifier circuit, a smoothing capacitor, and a control circuit for high-frequency switching the switching semiconductor elements in a predetermined sequence, wherein the circuit breaker and the boost inductors are provided. A boosting type three-phase full-wave rectifying device, characterized in that a three-phase bridge circuit is connected to which the phase line between the two is input and the positive and negative common lines of the three-phase full-wave rectifying circuit are output. 2. The step-up three-phase full-wave rectifier according to claim 1, wherein the control circuit includes a pause circuit that pauses the switching operation of the switching semiconductor element in a predetermined sequence for a certain period. apparatus. 3. The step-up type three-phase full-wave rectifier according to claim 1, wherein a diode is connected in antiparallel to the switching semiconductor element. 4. A boosting inductor provided on each of phase lines for feeding 3-phase AC power to a load side, a 3-phase full-wave rectifier circuit in which switching semiconductor elements are connected in a 3-phase bridge configuration, and the switching. In a control method of a boosting type three-phase full-wave rectifier equipped with a control circuit for high-frequency switching a semiconductor element in a predetermined sequence, a part of energy storage and release of the boosting inductor connected to each phase line is , A three-phase full-wave rectifier circuit and a positive and negative common line of the three-phase full-wave rectifier circuit are controlled to flow through a diode connected to form a three-phase bridge configuration. Control method of wave rectifier. 5. A three-phase full-wave rectifier circuit, in which boosting inductors, switching semiconductor elements are connected to each other in a three-phase bridge configuration, provided in each of phase lines for supplying three-phase AC power to a load side, and the switching. In a control method of a boosting type three-phase full-wave rectifier equipped with a control circuit for performing high-frequency switching of a semiconductor element in a predetermined sequence, in any section of each cycle of the frequency of an input voltage,
Only the switching semiconductor elements of appropriate two phases among the phases are subjected to high-frequency switching operation so that circulating current does not flow from the load side to the input side when energy is stored in the boosting inductor connected to each phase line. A method for controlling a step-up type three-phase full-wave rectifier, which is characterized in that: 6. The switching semiconductor element of each phase is controlled so as to perform a high frequency switching operation for a period substantially equal to ⅔ of a half cycle (π period) of each phase voltage, and to rest for the remaining period. A method of controlling a boosting type three-phase full-wave rectifier. 7. A high frequency switching operation of the switching semiconductor element is performed for one cycle (2) of each phase voltage so as to reduce switching loss of the switching semiconductor element.
7. The boosting according to claim 5 or claim 6, wherein the boosting is performed during periods of π / 3 to 2π / 3 and 4π / 3 to 5π / 3 of π), and is controlled in a period other than the rest period. Type 3 phase full wave rectifier control method.