JP3185846B2 - Power converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching type power converter (AC-DC-AC converter).

[0002]

2. Description of the Related Art As shown in FIG. 1, a combination circuit of a conventional half-bridge type AC / DC converter and a DC-AC inverter includes an AC power supply terminal 2 connected to one end of an AC power supply 1 and an AC power supply 1. A power-supply-side common terminal or ground terminal 3 connected to the other end of the power supply and the first reactor L for boosting
1 , the first and second transistors Q1, Q2, and the first
And second capacitors C1, C2, third and fourth transistors Q3, Q4, and a second reactor L for smoothing.
2, a load 6 connected between the first and second AC output terminals 4 and 5, and a control circuit 7. In addition, the second exchange
The output terminal 5 is connected to the common terminal on the power supply side, that is, the ground terminal 3.
Have been.

The first to fourth transistors Q1 to Q4 are insulated gate (MOS) field-effect transistors having a source connected to a bulk (substrate), and include first, second, third and fourth transistors. Main switches S1, S2, S3
, S4 and first, second, third and fourth diodes D1, D2, D3, D4 connected in anti-parallel. The first and second transistors Q1 and Q2 are connected in series with each other, and the connection point 8 is connected to the first reactor L1.
Is connected to the power supply terminal 2 via the. The source of the first transistor Q1 is connected to the midpoint 8 and its drain is connected to the first capacitor C1. The drain of the second transistor Q2 is connected to the midpoint 8 and its source is connected to the lower end of the second capacitor C2. First
And the second capacitors C1, C2 are connected in series with each other, and their midpoint 9 is connected to terminals 3 and 5 .
Therefore, the first and second transistors Q1, Q2 and the first
And the second capacitors C1 and C2 constitute a half-bridge type AC-DC converter.

The third and fourth transistors Q3 and Q4 constitute a half-bridge type inverter.
They are connected in series with each other. The series circuit of the third and fourth transistors Q3 and Q4 is connected in parallel to the series circuit of the first and second capacitors C1 and C2.
And the midpoint 9 between the first and second capacitors C1 and C2.
A load 6 is connected between the transistor and a middle point 10 of the third and fourth transistors Q3 and Q4 via a second reactor L2 for smoothing. The control circuit 7 is connected to the gates (control terminals) of the first and second transistors Q1 and Q2,
And the second transistors Q1 and Q2 are turned on and off alternately by a PWM wave (pulse width modulation wave) having a frequency sufficiently higher than the AC power supply voltage, and the gates of the third and fourth transistors Q3 and Q4 ( Control terminal),
It is turned on and off alternately so as to supply an AC voltage to the load 6 .

When the AC power supply 1 has an upward voltage (positive voltage)
During the period in which the first transistor Q1
Is turned on and the second transistor Q2 is turned off, the first capacitor C1 is connected in a first closed circuit including the power supply 1, the reactor L1, the first diode D1, and the first capacitor C1. Charged. At this time, if energy is stored in reactor L1, power supply 1
The first capacitor C1 is charged to a value higher than the power supply voltage Vin by both of the power and the energy stored in the reactor L1. During the positive voltage generation period, when the first transistor Q1 is off-controlled and the second transistor Q2 is on-controlled, a second capacitor C2, a power supply 1, a reactor L1 and a second transistor Q2 2
Is formed, and the voltage Vc2 of the second capacitor C2 is
And the voltage Vin of the power supply 1 is added to the reactor L1,
Energy is stored in the reactor L1. next,
During a period in which the power supply 1 is generating a downward voltage, that is, a negative voltage, the first transistor Q1 is turned on and the second transistor Q1 is turned on.
Is turned off, a third closed circuit comprising the power supply 1, the first capacitor C1, the first transistor Q1, and the reactor L1 is formed, and the voltage Vin of the power supply 1 and the voltage of the capacitor C1 are formed. A voltage equal to the sum of Vc1 is applied to reactor L1, where energy is stored. In the negative voltage period, when the second transistor Q2 is turned on and the first transistor Q1 is turned off, the fourth transistor consisting of the power supply 1, the second capacitor C2, the second diode D2, and the reactor L1. Is closed, the second capacitor C2 is charged to a value higher than the power supply voltage Vin by both the stored energy of the reactor L1 and the power supply 1.

The third and fourth transistors Q3 and Q4 convert DC to AC using the first and second capacitors C1 and C2 as power supplies. That is, while the third transistor Q3 is on, a current in the first direction flows through the load 6 in a closed circuit including the first capacitor C1, the first transistor Q3, the smoothing reactor L2, and the load 6. . Also, the fourth
During the ON period of the transistor Q4, the current in the second direction opposite to the first direction in the closed circuit of the second capacitor C2, the load 6 , the second reactor L2, and the fourth transistor Q4 is applied to the load 6. Flows to

[0007]

However, the load 6 does not always require a higher voltage than the AC power supply 1, and may require an output voltage having the same frequency and the same voltage value as the AC power supply 1. In the circuit of FIG. 1, even in such a case, the transistors Q3 and Q4 need to be turned on and off at a high frequency, resulting in large switching loss and poor efficiency. In addition, when a plurality of power converters having different output voltages are required, manufacturing them individually increases the cost.

It is an object of the present invention to provide a power converter capable of obtaining an output voltage in a plurality of stages and reducing switching loss when an input voltage and an output voltage are substantially the same. .

[0009]

The present invention Means for Solving the Problems] To achieve the above object, the ac power supply terminal to which one end of the AC camera turns are connected, and the AC output terminal to which one end of the load is connected, the AC power source is Ru connected other ends and are connected the load
A common terminal and first and second switches are connected in series.
And the midpoint between the first and second switches is the AC power supply terminal.
A first series circuit connected to the
Are switches connected in series and the first
A second series circuit connected in parallel to the series circuit of the above, and a circuit in which fifth and sixth switches are connected in series and connected in parallel to the first and second series circuits. And the midpoint of the fifth and sixth switches is
A third series circuit connected to a communication terminal ;
Second and third and a capacitor connected in parallel with the series circuit, the third and fourth connected re A spectrum between the midpoint of the switch and the intersection <br/> flow output terminal And when obtaining an AC output voltage substantially equal to the voltage of the AC power supply between the AC output terminal and the common terminal, setting the first and third switches to the same cycle as the voltage of the AC power supply. in oN-oFF control of the on-off controlling and said second and fourth switches simultaneously in said first and third switches and opposite phase, wherein the lower AC output voltage than the voltage of the AC power source AC output When obtaining between the terminal and the common terminal,
The first switch is turned on and off at the same cycle as the voltage of the AC power supply, and the second switch is turned on and off at the first cycle.
And the third switch is turned on / off at a repetition frequency higher than the frequency of the voltage of the AC power supply, and the fourth switch is turned on / off at an opposite phase to that of the third switch. ON / OFF control in phase and ON / OFF control of the fifth switch at a repetition frequency higher than the frequency of the voltage of the AC power supply, and ON / OFF control of the sixth switch in an opposite phase to the fifth switch. The present invention relates to a power conversion device including a switch control circuit for performing off control. It should be noted that an input stage reactor L1 and another reactor L3 can be provided as described in claim 2. The output voltage may be higher than the input AC power supply voltage. Claim 4
As shown in FIG. 7, an output stage reactor L2 and still another reactor L3 can be provided. Further, the output voltage may be substantially the same as the AC power supply voltage, may be lower than the AC power supply voltage, or may be higher than the AC power supply voltage. Also, as shown in claim 6
Output voltage lower than the AC power supply voltage, or
It can be higher than the power supply voltage .

[0010]

According to the first to sixth aspects of the present invention,
When obtaining an AC output voltage substantially equal to the AC power supply voltage, none of the first to sixth switches performs on / off control at a frequency higher than the frequency of the AC power supply voltage. Therefore,
The number of times of switching per unit time is reduced, and the efficiency is improved. According to the first to sixth aspects of the present invention, the output voltage can be changed in a plurality of stages by using a common switch. Therefore, a plurality of output voltages can be obtained with a simple configuration. Further, the power converters according to claims 1 to 6 can be mass-produced and used as various power converters having different output voltages.

[0011]

First Embodiment Next, a power converter according to an embodiment of the present invention will be described with reference to FIGS. However, in FIG. 2, substantially the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The circuit shown in FIG. 2 is equivalent to the first and second circuits shown in FIG.
Is connected in parallel to the series circuit of the first and second transistors Q1 and Q2 and the series circuit of the third and fourth transistors Q3 and Q4 instead of the capacitors C1 and C2 of FIG. A series circuit of fifth and sixth transistors Q5 and Q6 is connected in parallel to C, and the midpoint 9a of the fifth and sixth transistors Q5 and Q6 is connected to a terminal via a third reactor L3 for adjusting the capacitor voltage. 3 and 5, and the first to sixth transistors Q1
1 except that a control circuit 7a is formed so that .about.Q6 is controlled in three different stages according to the magnitude of the output voltage. The fifth and sixth transistors Q5 and Q6 are also insulated gate field effect transistors, and the fifth and sixth main switches S5 and S6 and the built-in fifth and sixth Diodes D5 and D
6

The control circuit 7a includes a control signal output line 1 connected to the gates of the first to sixth transistors Q1 to Q6.
1, 12, 13, 14, 15, and 16. The input voltage detection line 17 connected to the terminal 2, the DC voltage detection line 18 connected to the upper end of the capacitor C, and the AC output voltage detection line 19 connected to the terminal 4 are connected to the control circuit 7a. . Figure 3 is a view illustrating the control circuit 7a in principle, 50 synchronized with the input AC voltage Vin
It has a 50 Hz square wave pulse forming circuit 20 for forming a square wave pulse of Hz and an inversion pulse forming circuit 21 for forming a phase inversion pulse of the square wave pulse.
The 50 Hz square wave pulse forming circuit 20 is connected to the input AC voltage detection line 17 and forms a square wave pulse based on the input AC voltage Vin. The control circuit 7a further includes first, second, third, fourth, fifth and sixth transistors comprising a PWM pulse forming circuits 22,23,24,25,26,
27. First, second and third mode selection switch groups 28, 29 and 30 are provided between the eight pulse forming circuits 20 to 27 and the six control signal lines 11 to 16. The first mode selection switch group 28 includes a 50 Hz square wave pulse forming circuit 20 by switches a and b.
And the inverted pulse forming circuit 21 to Q1 and Q2 lines 1
1, 12 and at the same time 50
Hz square wave pulse forming circuit 20 and inverted pulse forming circuit 2
1 is connected to lines 13 and 14 of Q3 and Q4. In addition,
In the first mode, the fifth and sixth transistors Q5
, Q6 are kept off, so that no control signal is applied here. The second mode selection switch group 29 includes a pulse forming circuit 2 by switches e, f, g, h, i, and j.
0, 21, 24, 25, 26 and 27 are connected to lines 11 and 1
2, 13, 14, 15, 16 are connected. The third mode selection switch group 30 includes switches k, l, m, n, o,
The pulse forming circuits 22, 23, 20, 21, 2 by p
6, 27 to lines 11, 12, 13, 14, 15, 16
Connect to

The 50 Hz square wave pulse forming circuit 20 is shown in FIG.
As shown in FIG. 10, a zero-crossing detection circuit 31 connected to the input AC voltage detection line 17 and a T-type flip-flop 32 connected thereto are formed.
A 50 Hz square wave pulse shown in FIG. 10B is generated based on the zero cross detection of the Hz sine wave AC voltage Vin.
The inversion pulse forming circuit 21 is a well-known phase inversion circuit (NOT
FIG. 1 having the opposite phase to the pulse of FIG.
Output a square wave pulse of 0 (C). It should be noted that the inverted pulse forming circuit 21 does not rely on the phase inversion of the pulse forming circuit 20 and has a configuration similar to that of the pulse forming circuit 20 to obtain an inverted phase output, or the inverted phase of the flip-flop shown in FIG. The square wave pulse shown in FIG. 10C can be obtained from the output terminal.

As shown in FIG. 5, the PWM pulse forming circuit 22 for Q1 is connected to the rectifying / smoothing circuit 19a connected to the output voltage detecting line 19, and to the rectifying / smoothing circuit 19a and the reference voltage source 33. , An error amplifier 34 that outputs a voltage corresponding to the difference between the voltages, a triangular wave generating circuit 35 that generates a triangular wave voltage Vt1 at a frequency higher than the input AC voltage Vin as shown in FIG. The voltage comparator 3 which compares the output Vd1 with the triangular wave voltage Vt1 as shown in FIG. 8A and generates a PWM pulse shown in FIG.
6. The output voltage V0 is controlled by the change in the pulse width of the PWM pulse. The PWM pulse forming circuit 23 for Q2 shown in FIG. 3 comprises a phase inverting circuit of the output pulse of the PWM pulse forming circuit 22 for Q1, and generates the PWM pulse shown in FIG. In addition, in order to form the phase-inverted PWM pulse of FIG. 8C, an additional component similar to the comparator 36 of FIG. 5 is additionally provided, thereby comparing the triangular wave Vt1 with the error output Vd1. It may be configured to generate an output pulse having a phase opposite to that of the comparator 36.

The PWM pulse forming circuit 24 for Q3 is shown in FIG.
As shown in the figure, a reference signal forming circuit 36, an error amplifier (comparing circuit) 37, a triangular wave generating circuit 38, and a voltage comparator 3
9 The reference signal forming circuit 36 includes a well-known PLL circuit, and forms a sine wave in which the AC input voltage Vin detected on the output voltage detecting line 17 is synchronized with the AC output voltage V0 detected on the line 19, and has a desired amplitude. The amplitude is adjusted as described above to form a sine wave reference signal Vacr. The error amplifier 37 forms an error signal Vd2 corresponding to the difference between the reference signal Vacr and the output voltage V0 as shown in FIG. The triangular wave generating circuit 38 generates a triangular wave voltage Vt2 having a frequency sufficiently higher than the output voltage V0 as shown in FIG. The triangular wave generating circuit 38 can be used also as the triangular wave generating circuit 35 in FIG. The comparator 39 compares the error signal Vd2 with the triangular wave voltage Vt2 as shown in FIG. 9A, and outputs a PWM pulse for the transistor Q3 shown in FIG. 9B. The PWM pulse forming circuit 25 for Q4 shown in FIG. 3 comprises a phase inverting circuit, and outputs a PWM pulse for the transistor Q4 in FIG. 9C obtained by inverting the phase of the PWM pulse in FIG. 9B. A pulse forming circuit similar to the comparator 39 in FIG. 6 may be provided as a Q4 pulse forming circuit, and Vd2 and Vt2 may be compared by changing the polarity of this input to form the PWM pulse in FIG. 9C. .

The PWM pulse forming circuit 26 for Q5 is shown in FIG.
As shown in FIG. 7, the reference voltage source 41, the error amplifier 42, the triangular wave generation circuit 43, and the voltage comparator 44. The error amplifier 42 includes a capacitor voltage Vc on line 18 and a reference voltage Vc.
Generates a voltage corresponding to the difference from r. Triangular wave generation circuit 4
3 generates a triangular wave voltage having a frequency higher than 50 Hz and preferably several times higher than the frequency of the triangular wave voltage of FIG. The comparator 44 compares the triangular wave voltage and the error output with each other as shown in FIG.
Then, a PWM pulse as shown in FIG. 11F is generated. The width of the PWM pulse is controlled so as to keep the voltage of the capacitor C constant. The PWM pulse forming circuit 27 for Q6 is composed of a phase inverting circuit.
The pulse of FIG. 11 (G) in which the phase of the output pulse of the M pulse forming circuit 26 is inverted is generated.

Next, the operation of the apparatus shown in FIG. 2 will be described. FIG.
This device is formed so that the output voltage V0 can be changed in three stages. That is, a first mode in which the same output voltage V0 as the input AC voltage Vin is output, a second mode in which the output voltage V0 lower than the input AC voltage Vin is output, and an output voltage V0 higher than the input AC voltage Vin. And a third mode in which is output. Of course, it can be modified so that only one or two selected from the three modes can be obtained.

[0018]

[First mode] The same output voltage V as the input AC voltage Vin
In the first mode for obtaining 0, all the switches a to d of the first mode selection switch group 28 in FIG. 3 are turned on. As a result, the first to sixth transistors Q1 to Q1
6 is supplied with the control signals shown in FIGS.
That is, the first and third transistors Q1 and Q3 are 50H
The z-square wave pulse turns on intermittently at 180-degree intervals, and the second and fourth transistors Q2 and Q4 turn on Q1,
Operates in the opposite direction to Q3. Further, the fifth and sixth transistors Q5 and Q6 are kept off. Thus, during the period (t0 to t1) during which the input AC voltage Vin is a positive half-wave, the AC power supply 1, the first reactor L1, and the first transistor Q
1, the third transistor Q3, the second reactor L2,
A positive current flows in the closed circuit of the load 6. Also, during a period in which the input AC voltage Vin is a negative half-wave (t1 to t2), the AC power supply 1, the load 6, the second reactor L2, the fourth transistor Q4, the second transistor Q2, and the first reactor A negative current flows in the closed circuit of L1. This first
In this mode, the input AC voltage Vin becomes the output voltage V0 with a slight voltage drop. In this case, since the first to sixth transistors Q1 to Q6 are not turned on / off at a high frequency (for example, 20 kHz), the number of times of switching per unit time is reduced, and the decrease in efficiency due to switching loss is reduced.

[0019]

[Second Mode] In the second mode for obtaining an output voltage V0 lower than the input AC voltage Vin, the switches e to j of the second mode selection switch group 29 in FIG.
Thus, the 50 Hz square wave pulse forming circuit 20, the inverted pulse forming circuit 21, and the PWM pulse forming circuits 24-27 for Q3 to Q6 are connected to the gates of the first to sixth transistors Q1 to Q6 via the switches e to j. And the first to sixth
(B) to (G) of FIG.
Are supplied. As a result, during the positive half-wave period t0 to t1 of the input AC voltage Vin and the period when the third transistor Q3 is on, the AC power source 1, the first reactor L1, the first transistor Q1, the third transistor A positive current flows through the closed circuit of the transistor Q3, the second reactor L2 and the load 6. Further, during the period of the positive half-wave t0 to t1 of the input AC voltage Vin and the period when the fourth transistor Q4 is on, that is, when the third transistor Q3 is off, the AC power source 1, the first reactor L1, One transistor Q
1, a positive current flows in a closed circuit of the capacitor C, the fourth transistor Q4, the second reactor L2, and the load 6.

During the period from the negative half-wave t1 to t2 of the input AC voltage Vin in the second mode and the period when the fourth transistor Q4 is on, the AC power source 1, the load 6, the second reactor L2, A negative current flows through the closed circuit of the fourth transistor Q4, the second transistor Q2, and the first reactor L1. Further, during the negative half-wave period t1 to t2 of the input AC voltage Vin and the ON period of the third transistor Q3, that is, the OFF period of the fourth transistor Q4, the AC power source 1, the load 6, the second Reactor L2, 3rd
A negative current flows in a closed circuit of the transistor Q3, the capacitor C, the second transistor Q2, and the first reactor L1. Since the input AC voltage Vin is interrupted at a high frequency by the third and fourth transistors Q3 and Q4, an output voltage V0 lower than the input AC voltage Vin is obtained.

In the second mode, the capacitor C is connected to the first
To the circuit passing through the fourth transistors Q1 to Q4. For this reason, if the voltage Vc of the capacitor C is not controlled, this voltage Vc gradually increases. Therefore, the voltage Vc is controlled by discharging the electric charge of the capacitor C by using the fifth and sixth transistors Q5 and Q6. The discharge circuit of the capacitor C is formed as follows. First, when the input AC voltage Vin is in the positive half-wave period t0 to t1 and
During the ON period of the transistor Q6, the capacitor C,
First transistor Q1, first reactor L1, power supply 1, third reactor L3, and sixth transistor Q6
Discharge current of the capacitor C flows in the closed circuit composed of At this time, energy is stored in the first and third reactors L1, L3. Next, when the input AC voltage Vin is in the positive half-wave period t0 to t1 and the fifth transistor Q5 is on, the third reactor L3, the fifth transistor Q5, the first transistor Q1,. In a closed circuit including the first reactor L1 and the power supply 1, the reactors L1, L3
Is released, and the energy of the reactor L3 is returned to the power supply 1. The fifth and sixth transistors Q5 and Q6 are connected to the power source 1 as shown in FIGS.
At a frequency sufficiently higher than the voltage Vin, the discharge period of the capacitor C is controlled by controlling the width of the PWM pulse, and the voltage Vc of the capacitor C is kept substantially constant. During the period when the input AC voltage Vin is negative during the period t1 to t2 and the fifth transistor Q5 is on, the capacitor C, the fifth transistor Q5,
Third reactor L3, power supply 1, first reactor L1
And the charge of the capacitor C is released in a closed circuit including the second transistor Q2. Further, when the input AC voltage Vin is in the negative period t1 to t2 and the sixth transistor Q6 is on, the third reactor L3, the power supply 1, the first reactor L1, the second transistor Q2, and the sixth Reactors L1 and L3 in a closed circuit
Energy is released.

[0022]

[Third Mode] In the third mode for obtaining an output voltage V0 higher than the input AC voltage Vin, the switches k to p of the third mode selection switch group 30 in FIG. 3 are turned on.
Thereby, the pulse forming circuits 22, 23, 20, 21,.
26 and 27 are connected to the transistors Q1 to Q6. Thereby, as shown in FIG. 12, the first and second transistors Q1 and Q2 are turned on and off at a high frequency, and the third and fourth transistors Q3 and Q4 are turned on and off at the same cycle as the input AC voltage Vin. Fifth and sixth transistors Q5, Q6
Are intermittent at high frequencies.

In the third mode, the power supply 1, the first reactor L1, the first reactor L1, and the first reactor L1 are in the ON period of the first transistor Q1 when the input AC voltage Vin is in the positive half-wave period t0 to t1. A current in the first direction flows in a closed circuit including the transistor Q1, the third transistor Q3, the second reactor L2, and the load 6. At this time, the energy charged in the previous cycle is released to the first reactor L1, and the sum of the voltage Vin of the power supply 1 and the voltage of the first reactor L1 is output, and the amplitude is higher than the input AC voltage Vin. Is obtained. In the third mode, the input AC voltage Vin is in the positive half-wave period t0 to t1, and
During the ON period of the transistor Q2, the first direction is established in a closed circuit including the power supply 1, the first reactor L1, the second transistor Q2, the capacitor C, the third transistor Q3, the second reactor L2, and the load 6. And the energy is stored in the first reactor L1. At this time, the voltage Vc of the capacitor C is added to the input AC voltage Vin to become the output voltage V0.

In the third mode, the input AC voltage Vin
Is the negative half-wave period t1 to t2 and the second transistor Q2 is on, the power supply 1, the load 6, the second reactor L2, the fourth transistor Q4, the second transistor Q2, and the A current in the second direction flows in a closed circuit including one reactor L1. At this time, the input AC voltage Vin
And the voltage of the first reactor L1 is added to the output voltage V
It becomes 0. Further, the period t during which the input AC voltage Vin is a negative half-wave.
1 to t2 and the period when the first transistor Q1 is on, the power supply 1, the load 6, the second reactor L2, the fourth
A closed circuit comprising a transistor Q4, a capacitor C, a first transistor Q1 and a first reactor L1.
Current flows in the direction of. At this time, the voltage Vc of the capacitor C is added to the input AC voltage Vin to become the output voltage V0. During this period, energy is stored in the first reactor L1.

In the AC-AC conversion in the third mode, discharge of the capacitor C occurs, and this voltage decreases.
Therefore, the fifth and sixth transistors Q5 and Q6 are connected to the first
Further, the voltage Vc of the capacitor C is made constant by switching on and off at a frequency higher than that of the second transistors Q1 and Q2. The detailed operation will be described below. Input AC voltage Vin
During the positive half-wave period t0 to t1 and during the ON period of the sixth transistor Q6, the power supply 1 and the first reactor L
1. The capacitor is charged by a closed circuit including the first transistor Q1, the capacitor C, the sixth transistor Q6, and the third reactor L3. At this time, since the stored energy of the third reactor L3 is released, the capacitor C
Is the voltage Vin of the power supply 1 and the first and third reactors L1
, L3. That is, the output voltage V0
The capacitor C is charged with a higher voltage. The input AC voltage Vin is a positive half-wave period t0 to t1 and the fifth
During the ON period of the transistor Q5, a current flows through the closed circuit of the power supply 1, the first reactor L1, the first transistor Q1, the fifth transistor Q5, and the third reactor L3, and the energy flows through the third reactor L3. Is accumulated. During a period in which the input AC voltage Vin is a negative half-wave period t1 to t2 and the fifth transistor Q5 is on, the power supply 1, the third reactor L3, the fifth transistor Q5,
A current flows through a closed circuit including the capacitor C, the second transistor Q2, and the first reactor L1, and the capacitor C is charged by the sum of the voltage Vin of the power supply 1 and the voltages of the first and third reactors L1, L3. . The input AC voltage Vin is a negative half-wave period t1 to t2 and the sixth transistor Q
6, the power supply 1, the third reactor L3,
Transistor Q 6 of the sixth, the second transistor Q2 and the current to the first closed circuit including a reactor L1 of the flow, energy is stored in the third reactor L3.

[0026]

Second Embodiment Next, a power converter according to a second embodiment shown in FIG. 13 will be described. However, in FIG. 13, substantially the same parts as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. The circuit of FIG. 13 is different from the circuit of FIG. 2 in that first to sixth high-speed diodes D1a to D6a having a shorter storage time and a higher switching speed than the built-in diodes D1 to D6 of the first to sixth switches Q1 to Q6. , And six reactors L11, L12, L21, L22, L31, and L32.

First and second additional reactors L11, L12
Is connected between the output terminal of the first reactor L1 and the first and second transistors Q1 and Q2. The first high-speed diode D1a is connected between the drain-side line 51 of the first transistor Q1 and the drain of the second transistor Q2. The second high-speed diode D2a is connected between the source-side line 52 of the second transistor Q2 and the source of the first transistor Q1. The third additional reactor L21 is connected between the source of the third transistor Q3 and the second reactor L2.
The fourth additional reactor L22 is connected between the drain of the fourth transistor Q4 and the second reactor L2. The third high-speed diode D3a is connected between the drains of the third and fourth transistors Q3 and Q4. 4th
High-speed diode D4a is connected to the third and fourth transistors Q
3, connected between the sources of Q4. The fifth and sixth additional reactors L31 and L32 are connected between the third reactor L3 and the fifth and sixth transistors. Fifth
High-speed diode D5a is connected to the fifth and sixth transistors Q5
5, connected between the drains of Q6. The sixth high-speed diode D6a is connected to the fifth and sixth transistors Q5 and Q6.
Connected between the sources.

The first to sixth high-speed diodes D1a shown in FIG.
To D6a and the first to sixth additional reactors L11, L12, L
21, L22, L31 and L32 are the first to sixth in the circuit of FIG.
Built-in diodes D1 to D6 of the transistors Q1 to Q6
Has the effect of reducing the loss that occurs due to the storage time. The high frequency in the switching circuit of the input stage of the first and second transistors Q1, Q2, the switching circuit of the output stage of the third and fourth transistors Q3, Q4, and the switching circuit of the fifth and sixth transistors Q5, Q6 Since the intermittent operation is substantially the same,
This operation will be described by taking a switching circuit of the fourth transistors Q3 and Q4 as an example.

FIG. 14 shows the extracted third and fourth transistors Q3 and Q4 of FIG. In the case where the third and fourth transistors Q3 and Q4 are turned on and off at a high frequency in the second mode, the third transistor Q3 and the second reactor L2 are turned on while the third transistor Q3 is on.
The current flows in the circuit. Next, the third transistor Q3
Is turned off, the power supply 1, the first reactor L1, the first
, A capacitor C, a built-in diode D4 of a fourth transistor Q4, a second reactor L2,
Current flows in the closed circuit of the load 6. Thus, the energy stored in the second reactor L2 shown in FIG. 14 is also released. Then, when the third transistor is turned on again, the fourth diode D4 does not turn off immediately due to the storage time. As a result, a short circuit is formed by the third transistor Q3 and the fourth diode D4, causing not only a large power loss but also a possibility that the third and fourth transistors Q3 and Q4 may be damaged.

FIGS. 13 and 15 show circuits that can solve the above-mentioned problem. 13 and 15 to the third transistor Q3 is ON period of the current flows through the third transistor Q3 and the third additional reactor L2 1 and the second reactor L2. Next, when the third transistor Q3 is turned off, the third additional reactor L2
The energy stored in 1 and the second reactor L2 of the output line is released through both the fourth transistor Q4 and the fourth fast diode D4a. More specifically, in the second mode, the power supply 1, the first reactor L1, the first transistor Q1, the capacitor C, the fourth transistor Q4, the fourth high-speed diode D4a, the third
And the fourth additional reactors L21 and L22, the second reactor L2, and the load 6. To the next, the third transistor when the third transistor Q3 is turned on Q3
And the built-in diode D4 of the fourth transistor Q4 does not form a short circuit. Note that the third transistor Q
Even if there is a slight overlap between the on-period 3 and the on-period of the fourth high-speed diode D4a, if this is a short time, the power loss is small and the third transistor Q3 or the high-speed diode D4a is not damaged. Absent. The voltage drop of the fourth additional reactor L22 is set to be larger than the forward voltage of the built-in diode D4 of the fourth transistor Q4, and the built-in diode D4 is reverse-biased so that no current flows therethrough. You can also.

[0031]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. (1) An IGBT (insulated gate bipolar transistor) is used instead of the first to sixth transistors Q1 to Q6.
Transistor) can be used. Further, Q1 to Q6 can be an anti-parallel circuit of a bipolar transistor and a diode. (2) Between the ON periods of the first and second transistors Q1, Q2, the third and fourth transistors Q3, Q4
May be provided with a dead time (pause period) between the ON periods of the fifth and sixth transistors Q5 and Q6 to prevent short circuit due to storage. (3) Only the first and second modes, or the second and third modes
, Or only the first and third modes can be obtained. (4) In FIG. 13, the reactors L11 and L12, the reactors L21 and L22, and the reactors L31 and L32 may be respectively electromagnetically coupled, and the energy stored in one reactor may be released to the other reactor. L1, L11, L
12 mutual electromagnetic coupling, L2, L21, L22 mutual electromagnetic coupling,
Mutual electromagnetic coupling of L3, L31 and L32 is also possible. (5) In FIG. 13, the reactors L1, L2, L3
, One or two or all of them can be omitted. (6) In the case where only two types of modes, that is, a first mode for obtaining the same output voltage as the input voltage and a second mode for obtaining a voltage lower than the input voltage, are obtained, The first and third reactors L1 and L3 are omitted and the second reactor L
2, or the first and third reactors L1 and L2, omitting the second reactor L2.
L3 only. Further, when only two types of modes, ie, a first mode for obtaining the same output voltage as the input voltage and a second mode for obtaining the output voltage higher than the input voltage, are obtained,
As shown in claim 3, the second and third reactors L2,
It is possible to omit L3 and use only the first reactor L1, or to omit the first reactor L1 and use only the second and third reactors L2 and L3.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a conventional power converter.

FIG. 2 is a circuit diagram showing a power converter according to a first embodiment of the present invention.

FIG. 3 is a block diagram illustrating a control circuit of FIG. 2;

FIG. 4 is a block diagram showing a 50 Hz square wave pulse forming circuit of FIG. 3;

FIG. 5 is a block diagram showing a PWM pulse forming circuit for Q1 in FIG. 3;

FIG. 6 is a block diagram showing a PWM pulse forming circuit for Q3 in FIG. 3;

FIG. 7 is a block diagram showing a PWM pulse forming circuit for Q5 in FIG. 3;

FIG. 8 is a waveform chart showing a state of each unit in FIG. 5;

FIG. 9 is a waveform diagram showing a state of each unit in FIG. 6;

FIG. 10 is a waveform chart showing a state of each unit in FIG. 2 in a first mode.

FIG. 11 is a waveform chart showing a state of each unit in FIG. 2 in a second mode.

FIG. 12 is a waveform chart showing a state of each unit in a third mode.

FIG. 13 is a circuit diagram showing a power converter according to a second embodiment.

FIG. 14 is a diagram showing a part of FIG. 2;

FIG. 15 is a diagram showing a part of FIG. 13;

[Explanation of symbols]

 Q1 to Q6 Transistor C Capacitor L1 Reactor

Claims (6)

(57) [Claims] And 1. A ac power supply terminal, one end of Ru is connected in an AC power source, an AC output terminal to which one end of the load is connected, the other end of the AC power source is connected and the other end of the load contact
A common terminal that will be continued, the first and second switches are connected in series and the first
And the middle point of the second switch is connected to the AC power supply terminal.
A first series circuit, and a second series circuit in which third and fourth switches are connected in series, and a second series circuit is connected in parallel to the first series circuit.
And a fifth and sixth switch connected in series and connected in parallel with the first and second series circuits, and a midpoint of the fifth and sixth switches. Is the common terminal
A third series circuit connected to the first, a capacitor connected in parallel to the second and third series circuit, the AC output with a midpoint of said third and fourth switches and Li a vector which is connected between the terminal, the voltage of the AC power supply substantially identical to the AC output voltage when obtaining between the common terminal and said AC output terminal, said first and third A switch is simultaneously turned on / off at the same cycle as the voltage of the AC power supply, and the second and fourth switches are controlled.
Switch on and off controlled by the first and third switches and opposite phase, the lower the AC output voltage than the voltage of the AC power source when obtaining between the common terminal and said AC output terminal, said first 1 switch is turned on / off at the same cycle as the voltage of the AC power supply, and the second switch is turned on / off at a phase opposite to that of the first switch, and the third switch is turned on / off at the AC power supply. ON / OFF control at a repetition frequency higher than the frequency of the AC power supply, and ON / OFF control of the fourth switch in a phase opposite to that of the third switch, and sets the fifth switch at the frequency of the voltage of the AC power supply. ON / OFF control at a higher repetition frequency, and ON / OFF of the sixth switch in an opposite phase to the fifth switch.
A power conversion device comprising: a switch control circuit that performs off control. Wherein the ac power supply terminal, one end of Ru is connected in an AC power source, an AC output terminal to which one end of the load is connected, which is connected the other end of the AC power source and the other end of the load contact
A common terminal that will be continued, the first series circuit, the third and fourth switch is a circuit connected in series and the first series circuit in which the first and second switches are connected in series connected in parallel to and before
The middle point of the third and fourth switches is connected to the AC output terminal.
A second series circuit connected, connected to and the fifth and in parallel to the fifth and sixth a circuit switch is connected in series and the first and second series circuits The middle point of the switch 6 is the common terminal
A third series circuit connected to the first, a capacitor connected in parallel to the second and third series circuit, the ac power supply terminal and said first and second switches an input stage reactor connected between the midpoint, the fifth and the re a vector which is coupled between said common terminal midpoint of the sixth switch, the alternating current power supply voltage substantially When the same AC output voltage is obtained between the AC output terminal and the common terminal, the first and third switches are turned on and off at the same cycle as the voltage of the AC power supply, and the second and third switches are controlled. the fourth switch on and off controlled by the first and third switches and opposite phase, the lower the AC output voltage than the voltage of the AC power source when obtaining between the common terminal and said AC output terminal, Set the first switch to the same voltage as the AC power supply. On / off control in one cycle and on / off control of the second switch in an opposite phase to the first switch, and operation of the third switch at a repetition frequency higher than the frequency of the voltage of the AC power supply. On / off control and on / off control of the fourth switch in a phase opposite to that of the third switch, and on / off control of the fifth switch at a repetition frequency higher than the frequency of the voltage of the AC power supply And the sixth
And a switch control circuit for performing on / off control of the switch in a phase opposite to that of the fifth switch. 3. A ac power supply terminal, one end of Ru is connected in an AC power source, an AC output terminal to which one end of the load is connected, the other end of the AC power source is connected and the other end of the load contact
A common terminal that will be continued, and the first series circuit the first and second switches are connected in series, the third and fourth switches are circuits connected in series and the first series circuit and before being connected in parallel for
The middle point of the third and fourth switches is connected to the AC output terminal.
A second series circuit connected, connected to and the fifth and in parallel to the fifth and sixth a circuit switch is connected in series and the first and second series circuits The middle point of the switch 6 is the common terminal
A third series circuit connected to the first, second, and third series circuits; a capacitor connected in parallel to the first, second, and third series circuits; and an AC power supply terminal and the first and second switches. and Li a vector which is coupled between the point, the voltage of the AC power supply substantially identical to the AC output voltage when obtaining between the common terminal and said AC output terminal, said first and third A switch is simultaneously turned on / off at the same cycle as the voltage of the AC power supply and the second and fourth switches are controlled.
Switch on and off controlled by the first and third switches and opposite phase, the high AC output voltage than the voltage of the AC power source when obtaining between the common terminal and said AC output terminal, said first The first switch is turned on / off at a repetition frequency higher than the frequency of the voltage of the AC power supply, the second switch is turned on / off at an opposite phase to the first switch, and the third switch is turned on / off. On / off control at the same cycle as the voltage of the AC power supply, on / off control of the fourth switch in a phase opposite to that of the third switch, and control of the fifth switch at the frequency of the voltage of the AC power supply. ON / OFF control at a higher repetition frequency, and ON / OFF of the sixth switch in an opposite phase to the fifth switch.
A power conversion device comprising: a switch control circuit that performs off control. 4. A ac power supply terminal, one end of Ru is connected in an AC power source, an AC output terminal to which one end of the load is connected, the other end of the AC power source is connected and the other end of the load contact
A common terminal that will be continued, the first and second switches are connected in series and the first
And is connected to the middle point the alternating current power supply terminal of the second switch
A first series circuit, and a second series circuit in which third and fourth switches are connected in series, and a second series circuit is connected in parallel to the first series circuit.
A third series circuit which is a circuit in which fifth and sixth switches are connected in series and which is connected in parallel to the first and second series circuits; a capacitor connected in parallel to the second and third series circuit, and an output stage reactor connected between the midpoint of the third and fourth switch and the AC output terminal, the fifth between and the midpoint of the sixth switch and re a vector which is coupled between said common terminal, a voltage substantially identical to the AC output voltage of the AC power supply and the AC output terminal and the common terminal In this case, the first and third switches are turned on and off in the same cycle as the voltage of the AC power supply, and the second and fourth switches are set in opposite phases to the first and third switches. and on-off control, higher exchange than a voltage of the AC power source When obtaining an output voltage between said common terminal and said AC output terminal, the first switch-on at a higher repetition frequency than the frequency of the voltage of the AC power source off controlled and the second
Switch is turned on / off in a phase opposite to that of the first switch, and the third switch is turned on / off at the same cycle as the voltage of the AC power supply, and the fourth switch is turned on / off with the third switch. On / off control in phase opposite to that of the switch, and on / off control of the fifth switch at a repetition frequency higher than the frequency of the voltage of the AC power supply, and setting the sixth switch in antiphase with the fifth switch. And a switch control circuit that performs on / off control with the power converter. 5. A ac power supply terminal, one end of Ru is connected in an AC power source, an AC output terminal to which one end of the load is connected, the other end of the AC power source is connected and the other end of the load contact
A common terminal that will be continued, the first series circuit, the third and fourth switch is a circuit connected in series and the first series circuit in which the first and second switches are connected in series The second connected in parallel to
A third series circuit which is a circuit in which fifth and sixth switches are connected in series and which is connected in parallel to the first and second series circuits; A capacitor connected in parallel to the second and third series circuits; a first reactor connected between the AC power supply terminal and a midpoint of the first and second switches; a 3 and a second reactor that is connected between the midpoint and the front Ki交 flow power supply terminal of the fourth switch, connected between the midpoint and the common terminal of the fifth and sixth switch And a third reactor, and when obtaining an AC output voltage substantially equal to the voltage of the AC power supply between the AC output terminal and the common terminal, setting the first and third switches to the AC power supply. ON / OFF control in the same cycle as the voltage of Switch on and off controlled by the first and third switches and opposite phase, the lower the AC output voltage than the voltage of the AC power source when obtaining between the common terminal and said AC output terminal, said first Switch is turned on / off at the same cycle as the voltage of the AC power supply, and the second switch is turned on / off at a phase opposite to that of the first switch, and the third switch is turned on / off at the AC power supply. On / off control at a repetition frequency higher than the frequency of the voltage, and on / off control of the fourth switch in a phase opposite to that of the third switch, and operation of the fifth switch at a frequency lower than the frequency of the voltage of the AC power supply. On / off control at a high repetition frequency and the sixth
When the on / off control of the switch is performed in a phase opposite to that of the fifth switch to obtain an AC output voltage higher than the voltage of the AC power supply between the AC output terminal and the common terminal,
Controlling the first switch to be turned on and off at a repetition frequency higher than the frequency of the voltage of the AC power supply, and controlling the second switch to be turned on and off in a phase opposite to that of the first switch; and A switch is turned on / off in the same cycle as the voltage of the AC power supply, and the fourth switch is turned on / off in an opposite phase to the third switch, and the fifth switch is turned on and off of the voltage of the AC power supply. A power control device comprising: a switch control circuit for performing on / off control at a repetition frequency higher than the frequency and performing on / off control of the sixth switch in a phase opposite to that of the fifth switch. 6. An AC power supply terminal to which one end of an AC power supply is connected.
And an AC output terminal to which one end of a load is connected, the other end of the AC power supply is connected, and the other end of the load is connected.
A first terminal connected in series with a common terminal connected to the first and second switches;
And a circuit in which the circuit and the third and fourth switches are connected in series.
And a second connected in parallel with the first series circuit.
And a circuit in which fifth and sixth switches are connected in series.
And connected in parallel to the first and second series circuits.
And the midpoint of the fifth and sixth switches is the common
A third series circuit connected to a terminal, and connected in parallel to the first, second and third series circuits
Between the first and second switches.
A first reactor connected between a point and the AC power supply terminal
, A middle point of the third and fourth switches, and the AC output terminal.
And a second reactor connected between the AC power supply and an AC output voltage lower than a voltage of the AC power supply.
When obtaining between the output terminal and the common terminal, the first
Switch on at the same cycle as the voltage of the AC power supply.
Off control and turning the second switch on the first switch.
ON / OFF control in the opposite phase to the first switch and the third switch
A repetition frequency higher than the frequency of the AC power supply voltage
And the fourth switch is turned on and off with the third switch.
On / off control in the opposite phase to the switch of
The switch is repeatedly operated at a frequency higher than the frequency of the AC power supply.
On / off control at a predetermined frequency and the sixth switch
On / off control is performed in a phase opposite to that of the fifth switch,
The AC output voltage is higher than the AC power supply voltage.
When obtaining between the terminal and the common terminal, the first switch
Switch repeatedly higher than the frequency of the AC power supply voltage
On / off control with frequency and before the second switch
The on / off control is performed in a phase opposite to that of the first switch , the on / off control of the third switch is performed in the same cycle as the voltage of the AC power supply, and the fourth switch is controlled in phase opposite to the third switch. And the fifth switch is turned on / off at a repetition frequency higher than the frequency of the voltage of the AC power supply, and the sixth switch is turned on / off in a phase opposite to that of the fifth switch. A power conversion device comprising: a switch control circuit for controlling the power conversion device.