JP2011147300A - Power inverter, and power inverting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power inverter which can supply power in parallel to a plurality of loads from a single power supply, has small circuit scale and can adjust the supplied power. <P>SOLUTION: A power inverter 1 is composed of a plurality of driving circuits 10i connected in parallel with a DC power supply 2. Each of the driving circuits 10i includes: a DC reactor Ldci connected to the DC power supply 2 in series; a magnetic energy regeneration switch Bi including a plurality of reverse conducting semiconductor switches SWUi, SWVi, SWYi, SWXi having DC input ends to which a series circuit of the DC power supply 2 and the DC reactor Ldci and a capacitor CMi are connected and AC output ends to which a load LDi is connected; and a control circuit 13i. The control circuit 13i turns on and off the reverse conducting semiconductor switches SWUi, SWVi with a duty ratio of 0.5, and adjusts the duty ratio of the reverse conducting semiconductor switches SWYi, SWXi to 0.5 or less. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power reverse conversion device and a power reverse conversion method.

  Many power supply devices that supply an alternating current to an inductive load have been invented and used. In particular, for high power / high frequency applications, since switching loss cannot be ignored, switching control is required to perform soft switching.

  However, in order to realize soft switching, since switching is performed when the voltage (or current) applied to the switching element is 0, the control becomes passive control for monitoring the voltage or current. Therefore, it is difficult to realize a variable frequency or to achieve high efficiency at all operating points.

A technique capable of solving such a problem is disclosed in Patent Document 1. The power reverse conversion circuit disclosed in this document supplies an alternating current of a desired frequency from a direct current power source to a load using a magnetic energy regenerative switch composed of a capacitor and four reverse conducting semiconductor switches. This power reverse conversion circuit is generated in the capacitor by switching on and off the four reverse conducting semiconductor switches of the full bridge type MERS to cause the full bridge type MERS capacitor and the inductor of the inductive load to resonate in series. This circuit supplies an alternating current to an inductive load by voltage.
This power reverse conversion circuit can perform soft switching of four reverse conducting semiconductor switches without precise control, and can adjust the frequency of an alternating current supplied to a load.

JP 2008-92745 A

  However, the power reverse conversion circuit disclosed in this patent document cannot adjust the amount of power supplied to the load.

  Therefore, when individually controlling the amount of power flowing through a plurality of loads, all the systems from the DC power supply to the loads are required as many as the loads. For example, there are cases where a plurality of load coils for induction heating are connected to the same adjacent line, and it is desired to control the respective coil currents separately. However, in this configuration, in addition to the power reverse conversion circuit, a DC power supply is required for each load, the configuration becomes large, and the economy is poor.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power reverse conversion device and a power reverse conversion method that can adjust supply power and have a small circuit scale.
Another object of the present invention is to provide a power reverse conversion device and a power reverse conversion method that can supply power in parallel to a plurality of loads from one power source and that can adjust the supply power.

In order to achieve the above object, a power inverter according to the first aspect of the present invention provides:
A DC reactor connected in series with a DC voltage source;
First and second AC terminals; first and second DC terminals; first to fourth diodes; first to fourth self-extinguishing elements; and the first and second AC terminals. A capacitor connected between terminals or between the first and second DC terminals, wherein the first AC terminal has an anode of the first diode and a cathode of the second diode, The first DC terminal has a cathode of the first diode and the cathode of the third diode, and the second DC terminal has an anode of the second diode and an anode of the fourth diode. The second AC terminal is connected to the anode of the third diode and the fourth cathode, the first diode is connected to the first self-extinguishing element, and the second diode is connected to the second diode. The second self-extinguishing element includes the third self-extinguishing element; The third self-extinguishing element is connected to an anode, and the fourth self-extinguishing element is connected in parallel to the fourth diode, and the first DC terminal, the second DC terminal, A magnetic energy regenerative switch in which a series circuit of the DC voltage source and the DC reactor is connected between and an inductive load is connected between the first AC terminal and the second AC terminal;
A control circuit for outputting a signal for switching on and off each self-extinguishing element constituting the magnetic energy regeneration switch at a predetermined frequency;
With
The control circuit is configured to turn on a signal output to one of the first and third self-extinguishing element pairs and the second and fourth self-extinguishing element pairs. The duty ratio of off is fixed, and the duty ratio of on / off of the signal output to the other pair is variable.
It is characterized by that.

  For example, the predetermined frequency is a frequency equal to or lower than a resonance frequency determined by an inductance of the inductive load and a capacitance of the capacitor.

  For example, the control circuit turns on / off the plurality of self-extinguishing elements at a frequency equal to a resonance frequency determined by an inductance of the inductive load and a capacitance of the capacitor.

  For example, the control circuit sets the duty ratio of the one pair to 0.5, and the duty ratio of the other pair is variable to 0.5 or less.

  The control circuit may further include a function of adjusting the frequency of the output signal.

For example, there are a plurality of magnetic energy regeneration switches, and the plurality of magnetic energy regeneration switches are connected to different inductive loads,
The control means controls a signal output to the first to fourth self-extinguishing elements for each of the magnetic energy regeneration switches.

  For example, the self-extinguishing element is a reverse conducting semiconductor switch, and the diode is a parasitic diode of the reverse conducting semiconductor switch.

  For example, the present invention is used in an induction heating device.

  For example, the present invention is used in a motor control device.

In order to achieve the above object, a power reverse conversion method according to the second aspect of the present invention includes:
First and second AC terminals; first and second DC terminals; first to fourth diodes; first to fourth self-extinguishing elements; and the first and second AC terminals. A capacitor connected between terminals or between the first and second DC terminals, wherein the first AC terminal has an anode of the first diode and a cathode of the second diode, The first DC terminal has a cathode of the first diode and the cathode of the third diode, and the second DC terminal has an anode of the second diode and an anode of the fourth diode. The second AC terminal is connected to the anode of the third diode and the fourth cathode, the first diode is connected to the first self-extinguishing element, and the second diode is connected to the second diode. The second self-extinguishing element includes the third self-extinguishing element; The third self-extinguishing element is connected to an anode, and the fourth self-extinguishing element is connected in parallel to the fourth diode, and the first DC terminal, the second DC terminal, In a magnetic energy regenerative switch in which a series circuit of a DC voltage source and a DC reactor is connected between and an inductive load is connected between the first AC terminal and the second AC terminal.
A signal for switching on / off of each of the self-extinguishing elements constituting the magnetic energy regenerative switch is output at a predetermined frequency, and the pair of the first and third self-extinguishing elements; 2 and the fourth self-extinguishing element pair, the on / off duty ratio of the signal output to one pair is fixed, and the on / off duty ratio of the signal output to the other pair is Variable
It is characterized by that.

According to the present invention, power can be adjusted with a configuration having a small circuit scale.
Furthermore, according to the present invention, power can be supplied in parallel to a plurality of loads from one power source, and the supplied power can be adjusted.

It is a circuit diagram which shows the structure of the power reverse conversion apparatus concerning one Embodiment of this invention. (A) thru | or (d) is a figure which shows the example of the gate signal of the power reverse conversion apparatus shown in FIG. It is a figure for demonstrating operation | movement of the power reverse conversion apparatus shown in FIG. It is a figure for demonstrating operation | movement of the power reverse conversion apparatus shown in FIG. It is a figure for demonstrating operation | movement of the power reverse conversion apparatus shown in FIG. It is a figure for demonstrating operation | movement of the power reverse conversion apparatus shown in FIG. It is a figure for demonstrating operation | movement of the power reverse conversion apparatus shown in FIG. It is a figure for demonstrating operation | movement of the power reverse conversion apparatus shown in FIG. It is a figure for demonstrating operation | movement of the power reverse conversion apparatus shown in FIG. It is a figure for demonstrating operation | movement of the power reverse conversion apparatus shown in FIG. It is a figure which shows the example of a relationship between the gate signal and electric current and voltage of the power reverse conversion apparatus shown in FIG. It is a figure which shows the example of a relationship between the gate signal and electric current and voltage of the power reverse conversion apparatus shown in FIG. It is a figure which shows the change of an electric current and voltage at the time of changing the duty ratio of the gate signal of the power reverse conversion apparatus shown in FIG. It is a figure which shows the modification of the power reverse conversion apparatus shown in FIG. It is a figure which shows the modification of the power reverse conversion apparatus shown in FIG. It is a figure which shows the modification of the power reverse conversion apparatus shown in FIG. It is a figure which shows the modification of the power reverse conversion apparatus shown in FIG.

  Hereinafter, a power reverse conversion device according to an embodiment of the present invention will be described with reference to the drawings.

  The power reverse conversion device according to the present embodiment converts power supplied from one DC power source into AC power, can be supplied in parallel to a plurality of loads, and individually supplies power to the plurality of loads. Can be controlled.

  Hereinafter, an example in which AC power is supplied to n (n is a natural number of 2 or more) loads arranged in parallel will be described.

As shown in FIG. 1, the power inverter 1 according to the present embodiment includes a DC power supply 2 and a drive disposed in an i-th (i = 1 to n) load LDi when commonly disposed in all loads. Circuit 10i.
The DC power source 2 includes an AC power source 11, a full-wave rectifier circuit 12, and a smoothing capacitor CC.
The drive circuit 10i includes a direct current reactor Ldci, a magnetic energy regeneration switch Bi, and a control circuit 13i.

The magnetic energy regenerative switch Bi is composed of four reverse conducting semiconductor switches SWUi, SWXi, SWVi, SWYi, and a capacitor CMi.
The reverse conducting semiconductor switches SWUi, SWXi, SWVi, and SWYi of the magnetic energy regenerative switch Bi are diode units DUi, DXi, DVi, and DYi, and switch units SUi, connected in parallel to the diode units DUi, DXi, DVi, and DYi, respectively. SXi, SVi, SYi and gates GUi, GXi, GVi, GYi arranged in the switch units SUi, SXi, SVi, SYi.

In the magnetic energy regeneration switch Bi, the AC terminal AC1i has an anode of the diode unit DUi and a cathode of the diode unit DXi, and the DC terminal DCPi has a cathode of the diode unit DUi, a cathode of the diode unit DYi, and a positive electrode of the capacitor CMi, The direct current terminal DCNi is connected to the anode of the diode portion DXi, the anode of the diode portion DYi, and the negative electrode of the capacitor CMi, and the alternating current terminal AC2i is connected to the anode of the diode portion DVi and the cathode of the diode portion DYi.
A series circuit of a DC power supply 2 and a DC reactor Ldci is connected between the DC terminal DCPi and the DC terminal DCNi, and a load LDi is connected between the AC terminal AC1i and the AC terminal AC2i.

The output of the AC power supply 11 is input to the full-wave rectifier circuit 12.
One end of the current smoothing DC reactor Ldci for the load LDi is commonly connected to the positive output terminal of the full-wave rectifier circuit 12 and the connection node of the smoothing capacitor CC.

The AC power supply 11 outputs an AC voltage having a predetermined voltage at a predetermined frequency.
The full-wave rectifier circuit 12 is composed of, for example, a diode bridge circuit and the like, and full-wave rectifies the output voltage of the AC power supply 11 to output a pulsating DC pulsating voltage.
The smoothing capacitor CC smoothes the pulsating voltage output from the full-wave rectifier circuit 12 and functions as a DC voltage source. The capacitance of the smoothing capacitor CC is preferably larger than the total sum of the capacitors CMi.

The load LDi is composed of an inductive load such as an induction heating coil or a motor. The load LDi is represented by a series circuit of an inductor Li and a resistor Ri.
Note that the inductance and resistance of the load LDi may be different from each other.

On / off of the reverse conduction type reverse conduction type semiconductor switches SWUi, SWXi, SWVi, and SWYi of the magnetic energy regenerative switch Bi is switched by switching on / off of the switch units SUi, SXi, SVi, and SYi.
The switch units SUi, SXi, SVi, and SYi are turned on when an on signal is input to the gates GUi, GXi, GVi, and GYi, and are turned off when an off signal is input.
When the switch units SUi, SXi, SVi, and SYi are turned on, the diode units DUi, DXi, DVi, and DYi are short-circuited, and the reverse conducting semiconductor switches SWUi, SWXi, SWVi, and SWYi are turned on. When the switch units SUi, SXi, SVi, and SYi are turned off, the diode units DUi, DXi, DVi, and DYi function, and the reverse conducting semiconductor switches SWUi, SWXi, SWVi, and SWYi are turned off.
The reverse conducting semiconductor switches SWUi, SWXi, SWVi, and SWYi are, for example, N-channel silicon MOSFETs (MOSFETs: Metal-Oxide-Semiconductor Field-Effect Transistors).

  The control circuit 13i includes the gate signals SGUi shown in FIGS. 2A to 2D to the gates GUi, GXi, GVi, and GYi of the four switch units SUi, SXi, SVi, and SYi that constitute the magnetic energy regeneration switch Bi. SGXi, SGVi, SGYi are supplied. Each of the gate signals is composed of a high level signal and a low level signal.

  As shown in FIGS. 2A and 2B, the gate signals SGUi and SGVi are, for example, signals having a preset frequency f and a duty ratio of 0.5 (180 ° on). , The signals are almost in phase with each other. However, during the period ΔT in which one of the gate signals SGUi or SGVi changes from the high level to the low level, the other of the gate signals SGUi or SGVi does not change from the low level to the high level. This is to prevent the situation where the reverse conducting semiconductor switches SWUi and SWVi are simultaneously turned on and both ends of the load LDi are short-circuited.

  As shown in FIGS. 2A to 2D, the gate signal SGYi is a signal synchronized with the same frequency as the gate signal SGUi, and the gate signal SGXi is a signal synchronized with the same frequency as the gate signal SGVi. . However, the duty ratio between the gate signals SGYi and SGXi is 0.5 or less, and is variable in accordance with the adjustment of the knob 13ai of the control circuit 13i.

The resonance frequency fr of the capacitance C of the capacitor CMi and the inductance L of the inductor Li of the load LDi is fr = 1 / [2π√ (C · L)]. The frequency f of the gate signals SGUi, SGVi, SGXi, SGYi is set to a frequency equal to or lower than the resonance frequency fr. Further, it is desirable to adjust the capacitance of the capacitor CMi so that the load current ILDi becomes the maximum value at the timing when the gate signals SGUi, SGVi, SGXi, and SGYi are turned on / off.
In this embodiment, the capacitance of the capacitor CMi is adjusted so that the resonance period of the capacitor CMi and the inductor Li of the load LDi is 95% of the period of the gate signal.

  Next, the operation of the power inverter 1 having the above configuration will be described.

The operation of each drive circuit 10i is common.
The DC reactor Ldci of each drive circuit 10i stably supplies power (current) output from the DC power supply 2 into the drive circuit 10i.

  The control circuit 13i supplies the gate signals SGUi, SGVi, SGXi, SGYi to the switch units SUi, SVi, SXi, SYi. As described above, the gate signals SGUi, SGVi, SGXi, SGYi have the same frequency, SGUi and SGVi have a duty ratio of approximately 0.5, and SGXi and SGYi are 0.5 or less adjusted by the knob 13ai. The duty ratio is

In the control circuit 13i, when the duty ratio of the gate signals SGXi, SGYi is, for example, 0.5, the current flowing through the load LDi flows as indicated by arrows in FIGS. 3A to 3F.
In the following description, it is assumed that the initial state is the state at time T10 when the gate signals SGVi and SGXi are off signals, the gate signals SGUi and SGYi are on signals, and the current flows through the path of FIG.
For ease of understanding, the AC power supply 11 and the full-wave rectifier circuit 12 are not shown in FIGS. 3A to 3F.

(Time T11-T12)
At time T11, the control circuit 13i switches the gate signals SGVi and SGXi from the off signal to the on signal, and switches the gate signals SGUi and SGYi from the on signal to the off signal. The reverse conducting semiconductor switches SWVi and SWXi are switched on, and the reverse conducting semiconductor switches SWUi and SWYi are switched off.
As shown in FIG. 3A, the current flows from the load LDi through the AC terminal AC2i, through the ON reverse conducting semiconductor switch SWVi, through the DC terminal DCPi, and flows into the positive electrode of the capacitor CMi. The current flowing from the negative electrode of the capacitor CMi passes through the DC terminal DCNi, passes through the AC terminal AC1i through the ON reverse conducting semiconductor switch SWXi, and flows through the load LDi.

(Time T12-T13)
Due to resonance with the inductor Li, the capacitor CMi starts discharging at time T12 when the charging of the capacitor CMi ends, and current starts to flow as shown in FIG. 3B. The current flows from the load LDi through the AC terminal AC1i, through the ON reverse conducting semiconductor switch SWXi, through the DC terminal DCNi, and flows into the negative electrode of the capacitor CMi. The current flowing from the positive electrode of the capacitor CMi passes through the DC terminal DCPi, passes through the AC terminal AC2i via the ON reverse conducting semiconductor switch SWVi, and flows through the load LDi.

(Time T13-T14)
At time T13 when the voltage across the capacitor CM becomes substantially zero, current starts to flow as shown in FIG. 3C. The current passes through the AC terminal AC1i, passes through the AC terminal AC2i via the OFF reverse conducting semiconductor switch SWUi and the ON reverse conducting semiconductor switch SWVi, and passes through the AC terminal AC1i to turn on the reverse conducting semiconductor. The current flows to the load LDi through two routes, the route passing through the AC terminal AC2i through the switch SWXi and the off reverse conducting semiconductor switch SWYi.

(Time T14-T15)
At time T14, the control circuit 13i switches the gate signals SGUi and SGYi from the off signal to the on signal and switches the gate signals SGVi and SGXi from the on signal to the off signal at a preset frequency f.
The reverse conducting semiconductor switches SWUi and SWYi are turned on, and the reverse conducting semiconductor switches SWVi and SWXi are turned off.
As shown in FIG. 3D, the current flows from the load LDi through the AC terminal AC1i, through the ON reverse conducting semiconductor switch SWUi, through the DC terminal DCPi, and flows into the positive electrode of the capacitor CMi. The current flowing from the negative electrode of the capacitor CMi passes through the DC terminal DCNi, passes through the AC terminal AC2i via the ON reverse conducting semiconductor switch SWYi, and flows through the load LDi.

(Time T15-T16)
At time T15 when charging of the capacitor CMi ends due to resonance with the inductor Li, the capacitor CMi starts to discharge. As shown in FIG. 3E, the current flows from the load LDi through the AC terminal AC2i, through the ON reverse conducting semiconductor switch SWYi, through the DC terminal DCNi, and flows into the negative electrode of the capacitor CMi. The current flowing from the positive electrode of the capacitor CMi passes through the DC terminal DCPi, passes through the AC terminal AC1i via the ON reverse conducting semiconductor switch SWUi, and flows through the load LDi.

(Time T16-T17)
At time T16 when the voltage across the capacitor CMi becomes substantially zero, the current starts to flow as shown in FIG. 3F. The current passes through the AC terminal AC2i, passes through the AC terminal AC1i via the OFF reverse conducting semiconductor switch SWVi and the ON reverse conducting semiconductor switch SWUi, and passes through the AC terminal AC2i to turn on the reverse conducting semiconductor. The current flows to the load LDi through two routes, the route passing through the AC terminal AC1i through the switch SWYi and the off reverse conducting semiconductor switch SWXi.

  At time T17, the control circuit 13i switches the gate signals SGXi and SGVi to the on signal again and switches the gate signals SGUi and SGYi to the off signal at the preset frequency f.

By repeating the above operation, an alternating current as shown in FIG. 4 flows through the load LDi. FIG. 4 shows the relationship between the current ILDi and voltage VLDi of the load LDi and the voltage Vcm of the capacitor CMi in accordance with switching of the on signal / off signal of the gate signals SGVi, SGXi, SGUi, and SGYi. T17 corresponds to the above-described T10 to T17.
It can be seen that the capacitor voltage Vcm is repeatedly charged and discharged in response to switching of the gate signals SGUi, SGVi, SGXi, SGYi, the capacitor voltage Vcm is applied to the load LDi as the load voltage VLDi, and an alternating current flows to the load LDi. In addition, since the reverse conduction type semiconductor switch can be switched on and off at the timing when the voltage applied to the load LDi and each reverse conduction type semiconductor switch is almost zero, so-called soft switching is possible.

When the duty ratio of the gate signals SGXi and SGYi output from the control circuit 13i is, for example, 0.4, the current flows as shown in FIGS. 3A, 3B, 3D, 3E, 3G, and 3H.
In the following description, it is assumed that the initial state is the state at time T20 when the gate signals SGVi, SGYi, and SGXi are off signals, the gate signal SGUi is the on signal, and the current flows through the path of FIG.

(Time T21-T22)
At time T21, the control circuit 13i switches the gate signals SGVi and SGXi from the off signal to the on signal and the gate signal SGUi from the on signal to the off signal, and the gate signal SGYi holds the off signal. The reverse conducting semiconductor switches SWVi and SWXi are turned on, the reverse conducting semiconductor switch SWUi is turned off, and the reverse conducting semiconductor switch SWYi remains off.
As shown in FIG. 3A, the current flows from the load LDi through the AC terminal AC2i, through the ON reverse conducting semiconductor switch SWVi, through the DC terminal DCPi, and flows into the positive electrode of the capacitor CMi. The current flowing from the negative electrode of the capacitor CMi passes through the DC terminal DCNi, passes through the AC terminal AC1i through the ON reverse conducting semiconductor switch SWXi, and flows through the load LDi.

(Time T22-T23)
At time T22 when charging of the capacitor CMi ends due to resonance with the inductor Li, the capacitor CMi starts discharging, and current starts to flow as shown in FIG. 3B. The current flows from the load LDi through the AC terminal AC1i, through the ON reverse conducting semiconductor switch SWXi, through the DC terminal DCNi, and flows into the negative electrode of the capacitor CMi. The current flowing from the positive electrode of the capacitor CMi passes through the DC terminal DCPi, passes through the AC terminal AC2i via the ON reverse conducting semiconductor switch SWVi, and flows through the load LDi.

(Time T23-T24)
At time T23, according to the set duty ratio, the control circuit 13i switches the gate signal SGXi to the off signal, the gate signal SGVi remains on, and the gate signals SGUi and SGYi remain off. The reverse conducting semiconductor switches SWVi, SWUi, and SWYi are kept on / off, and the reverse conducting semiconductor switch SWXi is turned off. As shown in FIG. 3G, the current flows through the AC terminal AC1i, passes through the AC terminal AC2i through the OFF reverse conducting semiconductor switch SWUi and the ON reverse conducting semiconductor switch SWVi, and flows to the load LDi. The voltage of the capacitor CMi hardly fluctuates.

(Time T24-T25)
At time T24, the control circuit 13i switches the gate signals SGUi and SGYi from the off signal to the on signal and the gate signal SGVi from the on signal to the off signal at a preset frequency f, and the gate signal SGXi is the off signal. Leave.
The reverse conducting semiconductor switches SWUi and SWYi are turned on, the reverse conducting semiconductor switch SWVi is turned off, and the reverse conducting semiconductor switch SWXi is kept off.
As shown in FIG. 3D, the current flows from the load LDi through the AC terminal AC1i, through the ON reverse conducting semiconductor switch SWUi, through the DC terminal DCPi, and flows into the positive electrode of the capacitor CMi. The current flowing from the negative electrode of the capacitor CMi passes through the DC terminal DCNi, passes through the AC terminal AC1i via the ON reverse conducting semiconductor switch SWYi, and flows through the load LDi.

(Time T25-T26)
At time T25 when charging of the capacitor CMi ends due to resonance with the inductor Li, the capacitor CMi starts to discharge, and current flows as shown in FIG. 3E. The current flows from the load LDi through the AC terminal AC2i, through the ON reverse conducting semiconductor switch SWYi, through the DC terminal DCNi, and flows into the negative electrode of the capacitor CMi.
The current flowing from the positive electrode of the capacitor CMi passes through the DC terminal DCPi, passes through the AC terminal AC1i via the ON reverse conducting semiconductor switch SWUi, and flows through the load LDi.

(Time T26-T27)
At time T26, the control circuit 13i switches the gate signal SGYi to the off signal according to the set duty ratio, the gate signal SGUi remains on, and the gate signals SGVi and SGXi remain off. The reverse conducting semiconductor switches SWUi, SWVi, and SWXi are kept on / off, and the reverse conducting semiconductor switch SWYi is turned off.
As shown in FIG. 3H, the current flows through the AC terminal AC2i, and flows through the AC terminal AC1i to the load LDi through the OFF reverse conducting semiconductor switch SWVi and the ON reverse conducting semiconductor switch SWUi. The voltage of the capacitor CMi hardly fluctuates.

  At time T27, the control circuit 13i switches the gate signals SGXi and SGVi to the on signal and the gate signal SGUi to the off signal again at the preset frequency f. The gate signal SGYi is held as an off signal.

By repeating the above operation, an alternating current as shown in FIG. 5 flows through the load LDi. FIG. 5 shows the relationship between the current ILDi / voltage VLDi of the load LDi and the voltage Vcm of the capacitor CMi as the gate signals SGVi, SGUi, SGXi, SGYi are switched. T27 corresponds to the above-described T20 to T27.
As described above, according to the switching of the gate signals SGUi, SGVi, SGXi, SGYi, the capacitor voltage Vcm is applied to the load LDi in the forward direction, applied in the reverse direction, or not applied, and the AC is switched accordingly. It can be seen that current flows through the load LDi.
In this case, although not so-called soft switching, the applied voltage applied to the reverse conducting semiconductor switches SWUi, SWVi, SWXi, SWYi is small, and no large loss occurs.

  When the current and voltage of the load LDi when the duty ratio of the gate signals SGUi and SGVi is 0.5 and 0.4 are compared, the results are as shown in FIGS.

  6A and 6B show the case where the duty ratio of the gate signals SGUi, SGVi, SGXi, and SGYi is 0.5 as shown in FIG. 6D, and FIG. 6C. Thus, the relationship between the voltage applied to the load LDi and the current flowing through the load LDi when the duty ratio of the gate signals SGUi and SGVi is 0.5 and the duty ratio of the gate signals SGXi and SGYi is 0.4. It is shown in.

  Here, in FIGS. 6A and 6B, the solid lines are for the case where the duty ratio is all 0.5, and the broken lines are for the duty ratio of the gate signals SGUi and SGVi to 0.5, and SGXi and SGYi. This is for a duty ratio of 0.4.

  From the comparison of the solid line load voltage VLDi1 and the broken line load voltage VLDi2 shown in FIG. 6A, it can be confirmed that the load voltage is suppressed by the duty ratio. Similarly, it is confirmed from the solid line load current ILDi1 and the broken line load current ILDi2 shown in FIG. 6A that the load current decreases as the load voltage is suppressed. Further, as shown in FIGS. 6A and 6D, when the duty ratio of the gate signals SGUi and SGYi is 0.5, the load voltage is switched at almost 0, and soft switching is realized. On the other hand, as shown in FIGS. 6A and 6C, when SGYi is turned off before gate signal SGUi, the characteristic of soft switching is lost, but switching can be performed at a relatively low voltage. ing.

  Thus, the current flowing through the load LDi decreases as the duty ratio of the gate signals SGXi and SGYi is decreased from 0.5. For this reason, the power supplied to the load LDi also decreases. That is, the power supplied to the load LDi can be adjusted by operating the knob 13ai to adjust the duty ratio of the gate signals SGXi and SGYi within a range of 0.5 or less.

  Further, since the capacity of the smoothing capacitor CC is larger than the capacity of each capacitor CMi, power can be stably supplied to each drive circuit 10i, and each drive circuit 10i can be driven independently of each other. It is possible to individually adjust the power supplied to each load LDi.

  As described above, according to the power inverse conversion device 1 of the present embodiment, it is possible to individually supply power to a plurality of loads LDi from one current source by controlling the duty ratio of each gate signal. it can. Further, the power supplied to the load LDi can be individually controlled by controlling the duty ratio of the gate signal.

  As shown in FIG. 7, a current (power) measuring device 21i for measuring the load current ILDi is attached, and the measured value is fed back to the control circuit 13i, so that the control circuit 13i obtains a predetermined current value (power value). As described above, the duty ratio of the gate signals SGXi and SGYi may be controlled.

  In addition, as shown in FIG. 8, instead of the AC power supply 11, the full-wave rectifier circuit 12, and the smoothing capacitor CC, one DC power supply 22 may be used.

  In the above embodiment, the duty ratio of the gate signals SGXi and SGYi supplied to the reverse conducting semiconductor switches SWXi and SWYi among the reverse conducting semiconductor switches constituting the magnetic energy regenerative switch Bi is controlled. The duty ratio of the gate signals SGXi and SGYi supplied to the type semiconductor switches SWXi and SWYi may be fixed to 0.5, and the duty ratio of the gate signals SGUi and SGVi supplied to the reverse conduction type semiconductor switches SWUi and SWVi may be controlled. . However, it is desirable to control the duty ratio of the gate signal of the switch section on the lower voltage side, that is, the gate signals SGXi and SGYi.

As shown in FIG. 9, in the drive circuit 10i, a nonpolar capacitor CPi is connected between the AC terminals AC1i and AC2i instead of the capacitor CMi disposed between the DC terminals DCP and DCN of the magnetic energy regenerative switch Bi. May be. There is no need to change the gate signal.
In accordance with the on / off switching of the reverse conduction semiconductor switches SWUi, SWVi, SWXi, and SWYi of the magnetic energy regenerative switch Bi, the inductor Li and the capacitor CPi are supplied by the power supplied from the DC power supply 2 through the AC terminal AC1i or AC2i. Repeats resonance.
In this case, since the resonance in the flow path described with reference to FIGS. 3A, 3B, 3D and 3E is repeated without going through the reverse conducting semiconductor switches SW1 to SW4, the current burden on the reverse conducting semiconductor switches SW1 to SW4 is reduced. To do. Therefore, the lifetime of the reverse conducting semiconductor switches SW1 to SW4 is extended.
Of course, it is possible to provide both the capacitor CPi and the capacitor CMi. In this case, the resonance frequency of the inductor Li and the capacitor is determined by the combined capacitance of the capacitor CMi and the capacitor CPi and the inductance of the inductor Li.

  Furthermore, for example, a vibration suppression circuit 20 that attenuates the parasitic vibration as shown in FIG. 10 may be arranged.

Each reverse conducting semiconductor switch is not limited to a combination of a switch part and a diode part. In addition, the circuit configuration and the like can be changed as appropriate.
It is not necessary to provide all of the configurations described in the embodiment, and a combination of some configurations may be used as long as the intended purpose can be achieved.

In the above embodiment, the case where the resonance frequency fr is smaller than the frequency f of the gate signal has been described as an example. However, the resonance frequency fr and the frequency f of the gate signal may be equal or larger. However, the resonance frequency fr and the frequency f of the gate signal are preferably not more than twice. In particular, it is preferable that the resonance frequency fr and the frequency f of the gate signal are substantially equal.
When the resonance frequency fr is equal to the frequency f of the gate signal, there is no current flowing through the paths shown in FIGS. 3C and 3F, and the capacitor CMi and the inductor Li of the load LDi can be efficiently resonated.

Note that the type and combination of the loads LDi are arbitrary as long as they are inductive loads.
For example, the present invention can be used in a motor control device that controls a plurality of motors having different outputs.
In this case, the power supplied by controlling the duty ratio of the gate signal input to the reverse conduction type semiconductor switch of the magnetic energy regenerative switch connected to the motor to be used is brought close to the rating, and supplied from the magnetic energy regenerative switch to the unused motor. Reduce the power consumed. However, if the unused motor is operated at a low speed without being completely stopped, the burden on the motor when the stopped motor is restarted is reduced, and the driving becomes smooth.
In addition, it is also effective to use the present invention by connecting between one power source and a plurality of induction heating devices.
In this case, according to the present invention, desired power can be supplied to each induction heating device at a desired frequency. Thereby, the heating part of the heating object of the induction heating apparatus and the intensity of heating can be controlled.

DESCRIPTION OF SYMBOLS 1 Power reverse converter 2,22 DC power supply 10i Drive circuit 11 AC power supply 12 Full wave rectifier circuit 13i Control circuit 13ai Knob 20i Vibration suppression circuit 21i Ammeter or Wattmeter Bi Magnetic energy regeneration switch Ldci (i = 1-n) DC Reactor LDi Load Li Inductor Ri Resistor CC Smoothing capacitor CMi, CPi Capacitors SWUi, SWVi, SWXi, SWYi Reverse conduction type semiconductor switch SUi, SVi, SXi, SYi Switch unit DUi, DVi, DXi, DYi Diode unit GUi, GVi, GXi, GYi gate DCPi, DCNi DC terminal AC1i, AC2i AC terminal SGUi, SGVi, SGXi, SGYi Gate signal

Claims (10)

A DC reactor connected in series with a DC voltage source;
First and second AC terminals; first and second DC terminals; first to fourth diodes; first to fourth self-extinguishing elements; and the first and second AC terminals. A capacitor connected between terminals or between the first and second DC terminals, wherein the first AC terminal has an anode of the first diode and a cathode of the second diode, The first DC terminal has a cathode of the first diode and the cathode of the third diode, and the second DC terminal has an anode of the second diode and an anode of the fourth diode. The second AC terminal is connected to the anode of the third diode and the fourth cathode, the first diode is connected to the first self-extinguishing element, and the second diode is connected to the second diode. The second self-extinguishing element includes the third self-extinguishing element; The third self-extinguishing element is connected to an anode, and the fourth self-extinguishing element is connected in parallel to the fourth diode, and the first DC terminal, the second DC terminal, A magnetic energy regenerative switch in which a series circuit of the DC voltage source and the DC reactor is connected between and an inductive load is connected between the first AC terminal and the second AC terminal;
A control circuit for outputting a signal for switching on and off each self-extinguishing element constituting the magnetic energy regeneration switch at a predetermined frequency;
With
The control circuit is configured to turn on a signal output to one of the first and third self-extinguishing element pairs and the second and fourth self-extinguishing element pairs. The duty ratio of off is fixed, and the duty ratio of on / off of the signal output to the other pair is variable.
The power reverse conversion apparatus characterized by the above-mentioned. The predetermined frequency is a frequency equal to or lower than a resonance frequency determined by an inductance of the inductive load and a capacitance of the capacitor.
The power reverse conversion apparatus according to claim 1. The control circuit turns on and off the plurality of self-extinguishing elements at a frequency equal to a resonance frequency determined by an inductance of the inductive load and a capacitance of the capacitor.
The power reverse conversion apparatus according to claim 2. The control circuit is configured such that the duty ratio of the one pair is 0.5 and the duty ratio of the other pair is variable below 0.5.
The power reverse conversion device according to any one of claims 1 to 3, wherein the power reverse conversion device is provided. The control circuit further includes a function of adjusting a frequency of an output signal.
The power reverse conversion device according to any one of claims 1 to 4, wherein the power reverse conversion device is provided. There are a plurality of the magnetic energy regeneration switches, and the plurality of magnetic energy regeneration switches are connected to different inductive loads,
The control means controls a signal output to the first to fourth self-extinguishing elements for each of the magnetic energy regeneration switches.
The power reverse conversion device according to any one of claims 1 to 5, wherein The self-extinguishing element is a reverse conducting semiconductor switch, and the diode is a parasitic diode of the reverse conducting semiconductor switch.
The power reverse conversion device according to any one of claims 1 to 6, wherein   An induction heating device using the power reverse conversion device according to any one of claims 1 to 7.   A motor control device using the power reverse conversion device according to claim 1. First and second AC terminals; first and second DC terminals; first to fourth diodes; first to fourth self-extinguishing elements; and the first and second AC terminals. A capacitor connected between terminals or between the first and second DC terminals, wherein the first AC terminal has an anode of the first diode and a cathode of the second diode, The first DC terminal has a cathode of the first diode and the cathode of the third diode, and the second DC terminal has an anode of the second diode and an anode of the fourth diode. The second AC terminal is connected to the anode of the third diode and the fourth cathode, the first diode is connected to the first self-extinguishing element, and the second diode is connected to the second diode. The second self-extinguishing element includes the third self-extinguishing element; The third self-extinguishing element is connected to an anode, and the fourth self-extinguishing element is connected in parallel to the fourth diode, and the first DC terminal, the second DC terminal, In a magnetic energy regenerative switch in which a series circuit of a DC voltage source and a DC reactor is connected between and an inductive load is connected between the first AC terminal and the second AC terminal.
A signal for switching on / off of each of the self-extinguishing elements constituting the magnetic energy regenerative switch is output at a predetermined frequency, and the pair of the first and third self-extinguishing elements; 2 and the fourth self-extinguishing element pair, the on / off duty ratio of the signal output to one pair is fixed, and the on / off duty ratio of the signal output to the other pair is Variable
The power reverse conversion method characterized by the above-mentioned.

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