JP2008048487A - Ac/dc converter and its driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit system for converting an AC input voltage directly into a DC voltage while insulating the input and the output in DC. <P>SOLUTION: An AC input end 20 for inputting an AC voltage V2 is connected with an AC input circuit input end 42, and an AC input circuit output end 41 is connected with the rectifier circuit input end 32 through a first switch 2. Terminals of the AC input circuit output end 41 are connected by a second switch 3 and the rectifier circuit output end 31 is connected with a DC output end 10. The rectifier circuit input end 32 and the rectifier circuit output end 31 are insulated in DC, and a voltage having a polarity corresponding to that of an AC voltage V2 applied to the rectifier circuit input end 32 is converted into a DC voltage V1 and outputted. The voltage at the AC input circuit output end 41 is applied to the rectifier circuit input end 32 through conduction of the first switch 2, and the AC input circuit output end 41 is connected through conduction of the second switch 3 thus assuring a current route in an AC input circuit 4. Magnitude of the DC voltage V1 is controlled by regulating the time ratio of conduction state between the first and second switches 2 and 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an AC / DC converter that converts an AC voltage into a DC voltage, and a driving method thereof.

  In the AC inverter disclosed in Patent Document 1, as shown in FIG. 12, the power supply line 210a connected to the power supply terminal of the DC input unit 210 such as a battery (for example, DC12V) is a DC input composed of a choke coil and a capacitor. Connected to the filter 230. The switching circuit 240 is a push-pull type circuit for oscillating a DC power supply (DC 12 V) from the DC input unit 210 at 55 kHz, for example. The DC high voltage rectifier circuit 260 smoothes the waveform of the high voltage output (for example, 140 V) generated in the high voltage coil of the transformer 250 by the high frequency oscillation of the switching circuit 240, and outputs it to the drive circuit 280 from the DC output line 260a. The drive circuit 280 (AC circuit) is, for example, a well-known circuit in which four FETs are connected in an H-bridge form with respect to two AC output lines 280a and 280b. The AC output lines 280a and 280b are caused to generate an alternating voltage of, for example, 55 Hz by being alternately turned on at a ratio.

JP 2002-315351 A

  Patent Document 1 is a technique related to a DC / AC converter that converts a DC voltage into an AC voltage, and is not related to an AC / DC converter that converts an AC voltage into a DC voltage. There is no description about the circuit operation of inputting an AC voltage from the AC output unit and outputting a DC voltage to the DC input unit 210.

  Here, if the FET provided in the switching circuit 240 or the drive circuit 280 is an element having an anti-parallel diode, and the DC high-voltage rectifier circuit 260 is configured by a switching element, the switching circuit 240 or the drive circuit By controlling 280 as a rectifier circuit and DC high voltage rectifier circuit 260 as a switching circuit, it is possible to configure an AC / DC converter from the AC output section toward the DC input section 210. However, in this case, the circuit configuration becomes complicated and the number of parts increases. There is a possibility that a loss in circuit operation such as a switching loss may increase, and a sufficient power conversion efficiency may not be obtained, which is a problem. In addition, since there are many components, there is a possibility that an increase in circuit mounting area, an increase in component costs, and a manufacturing cost may be caused.

  The present invention has been made in view of the above-described background art, and proposes a novel circuit system that directly converts an input AC voltage into a desired DC voltage while DC-insulating the input and the output.

  In order to achieve the object, an AC / DC converter according to claim 1 includes a pair of AC input terminals to which an AC voltage is input, a pair of DC output terminals to which a DC voltage is output, an AC input circuit, The AC input circuit has a rectifier circuit, a first switch, and a second switch. The AC input circuit has a pair of AC input circuit input ends, a pair of AC input circuit output ends, and an AC input circuit output from the AC input circuit input end. At least one inductance element provided in a path leading to the end, and the rectifier circuit includes a pair of rectifier circuit input ends, a pair of rectifier circuit output ends, a transformer connected to the rectifier circuit input end, a transformer, It has a rectifier provided between the rectifier circuit output end, the AC input end and the AC input circuit input end are connected, and the AC input circuit output end and the rectifier circuit input end are connected via the first switch. Rectifier circuit output and And flow output end connected, the second switch and being connected between the AC input circuit output.

  In the AC / DC converter according to claim 1, the AC voltage input from the AC input end is input to the AC input circuit via the pair of AC input circuit input ends by the conduction of the second switch, and the AC input circuit receives the AC voltage. Electromagnetic energy having a polarity corresponding to the polarity of the voltage is accumulated in the inductance element. Thereafter, the electromagnetic energy accumulated in the inductance element is supplied to the rectifier circuit from the pair of AC input circuit output ends via the pair of rectifier circuit input ends by the conduction of the first switch and the non-conduction of the second switch. The In the rectifier circuit, it is galvanically isolated by the transformer, converted into a DC voltage by the rectifier, and outputs a DC voltage to the DC output terminal via the rectifier circuit output terminal.

  Thus, the AC / DC converter according to claim 1 can directly convert the input AC voltage into a desired DC voltage while DC-insulating the input and the output.

  The AC / DC converter according to claim 2 is the AC / DC converter according to claim 1, wherein the first switch includes two semiconductor switching elements having anti-parallel diodes, and a pair of AC input circuit output terminals. One of the switching elements is interposed between one of the pair of rectifier circuit inputs and one of the pair of rectifier circuits so that the emitter or the source is connected to the one AC input circuit output. Another one of the switching elements is interposed between the other and the other of the pair of rectifier circuit input ends so that the emitter or the source is connected to the other AC input circuit output end.

  In the AC / DC converter according to claim 2, even if a semiconductor switching element having an antiparallel diode is used as the first switch, the AC input circuit output terminal and the rectifier circuit input are independent of the polarity of the voltage appearing at the AC input circuit output terminal. Non-conduction between the ends can be achieved.

  The AC / DC converter according to claim 3 is the AC / DC converter according to claim 2, wherein the second switch includes two semiconductor switching elements each having an antiparallel diode, and constitutes a second switch. The two semiconductor switching elements are connected in series with their emitters or sources connected.

  In the AC / DC converter according to the third aspect, even if a semiconductor switching element having an antiparallel diode is used as the second switch, the second switch can be made non-conductive.

  The AC / DC converter according to claim 4 is the AC / DC converter according to claim 2, wherein the second switch includes two semiconductor switching elements each having an antiparallel diode, and constitutes a second switch. One semiconductor switching element is connected in series with each collector or drain connected.

  Even in the AC / DC converter according to the fourth aspect, the second switch can be made non-conductive even if a semiconductor switching element having an antiparallel diode is used as the second switch.

  An AC / DC converter according to claim 5 is the AC / DC converter according to claim 4, wherein one of the semiconductor switching elements constituting the first switch is connected to one emitter or source and the emitter or source. A current sense resistor is interposed between a connection point between the emitter or the source of the semiconductor switching element constituting the two switches and one of the output terminals of the AC input circuit.

  Thereby, the electric current which flows into an alternating current input circuit output terminal can be detected. Since both the current that flows due to the conduction of the first switch and the current that flows due to the conduction of the second switch flow at the output terminal of the AC input circuit, the current can be detected at all times.

  An AC / DC converter according to claim 6 is the AC / DC converter according to claim 1, wherein the first switch includes two semiconductor switching elements each having an antiparallel diode and constitutes the first switch. The two semiconductor switching elements are connected in series with their emitters or sources connected to each other, and a first switch is interposed between one of the pair of AC input circuit output ends and one of the pair of rectifier circuit input ends, The other of the pair of AC input circuit output ends and the other of the pair of rectifier circuit input ends are directly connected, and the second switch includes two semiconductor switching elements having anti-parallel diodes, and two of the two switches constituting the second switch. The semiconductor switching element is characterized in that respective emitters or sources are connected in series with each other.

  The emitters or sources of the semiconductor switching elements having two anti-parallel diodes are connected to each other, and the semiconductor switching elements are connected in series to form a first switch. The emitters or sources of the second switch are also connected to each other, and the semiconductor switching elements are connected in series. For this reason, the reference potential for controlling the conduction of the semiconductor switching elements is common, and a common drive power supply can be used for each of the first switch and the second switch. It is possible to simplify conduction control and drive power supply.

  The AC / DC converter according to claim 7 is the AC / DC converter according to claim 3 or 6, wherein the emitters or sources of the two semiconductor switching elements constituting the second switch are grounded. It is connected to a potential.

  An AC / DC converter according to claim 8 is the AC / DC converter according to claim 1, wherein the rectifying unit includes a semiconductor switching element having an antiparallel diode, and the antiparallel diode is a center tap type. It constitutes either a rectifier circuit or a bridge-type full-wave rectifier circuit.

  Thus, by switching control of the semiconductor switching element, when a DC voltage is input from the DC output terminal, the DC voltage can be converted into a bipolar voltage and input to the transformer. Therefore, the AC / DC converter can be used as a DC / AC converter.

  An AC / DC converter according to claim 9 is provided with an AC input circuit having an inductance element to which an AC voltage is applied, a rectifier circuit that insulates a bipolar voltage into a DC voltage, and a rectifier circuit. It has between the alternating current input circuit, It has the 1st switch which interrupts an electric current, and the 2nd switch which short-circuits and open | releases the 1st switch side of an alternating current input circuit, It is characterized by the above-mentioned.

  In the AC / DC converter according to claim 9, the first switch is turned off and the second switch is turned on to short-circuit the first switch side of the AC input circuit having an inductance element to which an AC voltage is applied. Accordingly, electromagnetic energy corresponding to the AC voltage is stored in the inductance element. Thereafter, the second switch is turned off and the first switch is turned on to release the electromagnetic energy accumulated in the inductance element to the rectifier circuit. In the rectifier circuit, the AC voltage is galvanically isolated and rectified to output the DC voltage.

  According to a tenth aspect of the present invention, there is provided a driving method for an AC / DC converter including a pair of AC input terminals to which an AC voltage is input, a pair of DC output terminals to which a DC voltage is output, an AC input circuit, and a rectifier circuit. The AC input circuit has a pair of AC input circuit input ends, a pair of AC input circuit output ends, and an AC input circuit input end to an AC input circuit output end. And a rectifier circuit having a pair of rectifier circuit input terminals, a pair of rectifier circuit output terminals, a transformer connected to the rectifier circuit input terminal, a transformer and a rectifier circuit output. A rectification unit provided between the AC input terminal and the AC input circuit input terminal, the AC input circuit output terminal and the rectifier circuit input terminal connected via the first switch, Circuit output terminal and DC output Are connected to each other and a second switch is connected between the output terminals of the AC input circuit. The driving method converts the AC voltage and outputs the DC voltage in the AC / DC converter, and includes a first switch and a second switch. Are characterized in that they are alternately conducted through a period in which both are in a conducting state.

  In the driving method of the AC / DC converter according to the tenth aspect, when the first switch and the second switch are alternately conducted, the first switch and the second switch are switched with a period in which both are in the conducting state.

  Thereby, the input AC voltage can be directly converted into a DC voltage. In addition, there is no period during which the first switch and the second switch are both non-conductive, and the path of the current flowing through the inductance element is always secured, so that a voltage surge does not occur. Generation of a surge voltage due to electromagnetic energy accumulated in the inductance element without forming a current path can be prevented.

  An AC / DC converter driving method according to claim 11 is the AC / DC converter driving method according to claim 10, wherein the time ratio during which the second switch occupies in the conduction cycle of the first and second switches. Is controlled to have a negative correlation with the peak value in the AC voltage.

That is, the ratio of the time during which the second switch is turned on is controlled to be longer as the peak value (that is, absolute value) of the AC voltage is smaller and shorter as the peak value is larger. Further, when the second switch is in a conductive state, energy is stored in the inductance element, and when the second switch is in a non-conductive state and the first switch is in a conductive state, the voltage is boosted by the energy stored in the inductance element in addition to the AC voltage. A voltage is applied to the rectifier circuit.
The longer the second switch is turned on, the longer the time for storing energy in the inductance element. Therefore, the amount of energy stored in the inductance element is large, and the boosting is large. On the other hand, the shorter the time for which the second switch is conducted, the shorter the time for storing energy in the inductance element. Therefore, since the energy stored in the inductance element is also small, the boosting is small.
That is, the boost is larger as the peak value of the AC voltage is smaller, and the boost is smaller as the peak value of the AC voltage is larger. By controlling in this way, the voltage applied to the rectifier circuit can be controlled, so that fluctuations in the DC voltage output to the DC output terminal can be suppressed.

  A method for driving an AC / DC converter according to a twelfth aspect is the method for driving an AC / DC converter according to the tenth aspect, wherein the first switch is turned on when the second switch is turned on (step 1). ), The step of turning off the second switch when the first switch is on (step 2), the step of turning on the second switch while the first switch is on (step 3), A step (step 4) of turning off the first switch in a conductive state, and repeating (step 1) to (step 4).

  After the first switch is turned on (step 1), the second switch is turned off (step 2), and the first switch is turned off (step 4) under the conductive state of the second switch. By repeating the above, the electromagnetic energy of the AC voltage accumulated in the inductance element is output as a DC voltage.

  Also, the first switch is turned on before the second switch is turned off (step 1), and the second switch is turned on before the first switch is turned off (step 3). A path for the current flowing through the inductance element of the circuit is always secured, and no voltage surge is generated.

  According to the present invention, an input AC voltage can be directly converted into a desired DC voltage while the input and the output are galvanically isolated.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a DC / AC converter according to the present invention will be described below in detail with reference to FIGS.

  In the AC / DC converter of FIG. 1 illustrating the principle of the present invention, an AC voltage V2 is input from a pair of AC input terminals 20, and a DC voltage V1 is output from a pair of DC output terminals 10. The AC input terminal 20 is connected to a pair of AC input circuit input terminals 42 of the AC input circuit 4. One of the AC input circuit output terminals 41 of the AC input circuit 4 is connected via the first switch 2 and the other of the AC input circuit output terminals 41 of the AC input circuit 4 is directly connected to the pair of rectifier circuit input terminals 32 of the rectifier circuit 1. It is connected to the. The terminals of the AC input circuit output terminal 41 are connected by the second switch 3. The pair of rectifier circuit output terminals 31 of the rectifier circuit 1 are connected to the pair of DC output terminals 10.

  The AC input circuit 4 has a coil L as at least one inductance element provided in a path from the AC input circuit input terminal 42 to the AC input circuit output terminal 41.

  Although illustration is omitted, the rectifier circuit 1 includes a transformer connected to the rectifier circuit input end 32 and a rectifier provided between the transformer and the rectifier circuit output end 31. Therefore, the rectifier circuit input terminal 32 and the rectifier circuit output terminal 31 are galvanically insulated, and a voltage having a polarity corresponding to the polarity of the AC voltage V2 applied to the rectifier circuit input terminal 32 is set to the DC voltage V1. It converts and outputs to the output terminal 31 of a rectifier circuit.

The polarity of the voltage applied to the rectifier circuit input terminal 32 changes depending on the AC voltage V <b> 2, and the voltage changes depending on the operation of the first switch 2 and the second switch 3. The operating frequency of the first switch 2 and the second switch 3 is operated at a sufficiently high frequency compared to the frequency of the AC voltage V2.
The first switch 2 and the second switch 3 are turned on alternately after a period in which both are in a conductive state. When the second switch 3 is in the conductive state, the AC input circuit output terminal 41 is short-circuited, and a path through which the current in the AC input circuit 4 flows is secured. At this time, energy is accumulated in the coil L.
When the second switch 3 is in a non-conductive state and the first switch 2 is in a conductive state, a voltage boosted by the energy accumulated in the coil L in addition to the AC voltage V2 is passed through the rectifier circuit input terminal 32 via the first switch 2. To be applied.
Since at least one of the first switch 2 and the second switch 3 is in a conductive state, a current path flowing through the coil L is ensured, and a voltage surge does not occur. When the polarity of the AC voltage V2 is reversed, the direction of the current is reversed and the voltage applied to the rectifier circuit input terminal 32 is also reversed. However, since the rectification unit of the rectifier circuit 1 rectifies, the polarity of the AC voltage V2 is changed. Regardless, a DC voltage is output to the DC output terminal 10.
Further, by controlling the time ratio during which the second switch 3 is in the conduction cycle of the first switch 2 and the second switch 3, the amount of energy accumulated in the coil L can be controlled. Here, as described above, the energy stored in the coil L is used for boosting when the second switch 3 is in a non-conductive state and the first switch 2 is in a conductive state. Therefore, considering the voltage value of the AC voltage V2 when the second switch 3 is turned off and the first switch 2 is turned on, the voltage applied to the rectifier circuit input terminal 32 (in addition to the AC voltage V2) Therefore, the magnitude of the DC voltage V1 output to the DC output terminal 10 can be controlled.
Therefore, a DC voltage V1 having a desired voltage value can be obtained regardless of the polarity of the AC voltage V2.

  The circuit diagram of FIG. 2 is the AC / DC converter according to the embodiment. The rectifier circuit 1 has a common emitter terminal and a transformer TR having a pair of terminals as input terminals of the rectifier circuit at both ends of the primary side winding and three terminals including an intermediate tap in the secondary side winding. IGBT elements T1 and T2 having collector terminals connected to terminals at both ends excluding the intermediate tap of the secondary winding. A smoothing capacitor C0 is connected between the emitter terminals of the IGBT elements T1 and T2 and the intermediate tap of the transformer TR, and the DC voltage V1 is output with the emitter terminals of the IGBT elements T1 and T2 set to the negative side. In this case, the IGBT elements T1 and T2 are semiconductor switching elements having antiparallel diodes, and the antiparallel diodes function as rectifying elements. A rectification unit is configured by connecting the antiparallel diode, the IGBT elements T1 and T2 and the secondary side of the transformer TR to form a center tap type rectifier circuit.

  The collector terminals of IGBT elements T5 and T6 are connected to the pair of terminals of the primary side winding of the transformer TR, respectively. The emitter terminals of the IGBT elements T5 and T6 are connected to one ends of the coils L1 and L2 of the AC input circuit 4, respectively. The IGBT element T5, T6 constitutes the first switch 2. Thus, even when IGBT elements T5 and T6, which are semiconductor switching elements having antiparallel diodes, are used as the first switch 2, the AC input circuit output terminal and the rectifier circuit are independent of the polarity of the voltage appearing at the AC input circuit output terminal. Non-conduction between the input terminals can be achieved.

  Further, the emitter terminal of the IGBT element T7 is connected to the connection path between the emitter terminal of the IGBT element T5 and one end of the coil L1, and the connection path between the emitter terminal of the IGBT element T6 and one end of the coil L2 is connected to the end of the IGBT element T8. The emitter terminal is connected. The IGBT elements T7 and T8 are connected in series with their collector terminals connected to each other. The IGBT element T7, T8 constitutes the second switch 3. Thereby, even if IGBT elements T7 and T8, which are semiconductor switching elements having antiparallel diodes, are used as the second switch 3, the second switch 3 can be made non-conductive.

  Here, each IGBT element T1, T2, T5-T8 is provided with the antiparallel diode. The IGBT elements T5 to T8 correspond to the semiconductor switching elements in the claims. In the AC input circuit 4, one ends of the coils L1 and L2 are a pair of AC input circuit output ends. The other ends of the coils L1 and L2 are a pair of AC input circuit input ends. The smoothing capacitor C1 is connected between the other ends of the coils L1 and L2.

    Hereinafter, in FIG. 3 to FIG. 7, the driving method of the AC / DC converter of the embodiment (FIG. 2) is shown step by step.

  In the operation state (1) of FIG. 3, when the IGBT elements T7 and T8 are in a conductive state, a coil current IL corresponding to the AC voltage V2 flows, and electromagnetic energy is accumulated in the coils L1 and L2. The direction of the coil current IL changes according to the AC voltage V2. In the operation state (1) of FIG. 3, the AC voltage V2 indicates a case where the coil L1 side is at a high potential. The coil current IL flows through a path that reaches the coil L2 via the coil L1, the antiparallel diode of the IGBT element T7, and the IGBT element T8.

  Next, the operation state (2) in FIG. 4 is entered. The IGBT elements T5 and T6 are conducted while the IGBT elements T7 and T8 are maintained in the conducting state. The coil current IL continues to flow from the operation state (1) in FIG.

  In this case, no current flows through the IGBT elements T5 and T6 because the IGBT elements T7 and T8 are maintained in the conductive state.

  Next, the operation state (3) in FIG. 5 is entered. The IGBT elements T7 and T8 are made non-conductive while the IGBT elements T5 and T6 are maintained in the conductive state. The coil current IL flowing from the coils L1 and L2 is supplied from the coil L1 through the antiparallel diode of the IGBT element T5, the primary winding of the transformer TR (the winding on the left side of the transformer TR in FIG. 5), and the IGBT element T6. It flows along the route to the coil L2. Here, since the IGBT elements T5 and T6 are already in the conductive state in the operation state (2) of FIG. 4, no turn-on loss occurs. The transformer TR is excited by this current, and a voltage is generated on the secondary side of the transformer TR (the right side of the transformer TR in FIG. 5). Since the exciting current flows from the reference terminal on the primary side of the transformer TR, a voltage is generated on the secondary side of the transformer TR so that the potential of the reference terminal becomes high. This voltage causes a current to flow from the intermediate tap of the transformer TR to the secondary winding of the transformer TR via the capacitor C0 and the antiparallel diode of the IGBT element T1. In FIG. 5, a positive voltage is generated with respect to the intermediate tap at the upper terminal on the secondary side of the transformer TR. The direction of the current due to this is such that the current flows from the cathode to the anode of the antiparallel diode of the IGBT element T2. Therefore, no current flows through the path of the IGBT element T2.

  In this case, between the collector and emitter terminals of the IGBT element T7, the inter-terminal voltage does not change before and after the change from the conductive state to the non-conductive state. This is because the antiparallel diode of the IGBT element T7 maintains a conductive state. For this reason, no switching loss occurs during the conduction control of the IGBT element T7.

  Next, the operation state (4) in FIG. 6 is entered. The IGBT elements T7 and T8 are conducted while the IGBT elements T5 and T6 are maintained in the conducting state. As in the case of the operating states (1) and (2) in FIGS. 3 and 4, the coil current IL corresponding to the AC voltage V2 flows through the IGBT elements T7 and T8, and electromagnetic energy is applied to the coils L1 and L2. Accumulate. In the operation state (4) in FIG. 6, the AC voltage V2 indicates a case where the coil L1 side is at a high potential.

  At the same time, the exciting current of the transformer TR flows to the primary side. An exciting current of the transformer TR flows through a path returning to the primary side winding via the antiparallel diode of the IGBT element T6, the IGBT element T8, the IGBT element T7, and the antiparallel diode of the IGBT element T5.

  In the operation state (4) of FIG. 6, since the primary side winding of the transformer TR is short-circuited, an exciting current flows through the primary side winding and does not flow through the secondary side winding. In this case, the voltage between the collector and emitter terminals of the IGBT element T7 does not change before and after the IGBT element T7 changes from the non-conducting state to the conducting state, so that no turn-on loss occurs when the IGBT element T7 is conducting.

  Next, the operation state (5) in FIG. 7 is entered. The IGBT elements T5 and T6 are non-conductive while the IGBT elements T7 and T8 are conductive. The coil current IL continues to flow from the operation state (4) in FIG.

  At the same time, the exciting current of the transformer TR flows to the secondary side instead of the primary side. An exciting current of the transformer TR flows from the intermediate tap to a path returning to the secondary winding through the capacitor C0 and the antiparallel diode of the IGBT element T2.

When the transformer TR is reset, the operation state (1) in FIG. 3 is restored. Thereafter, the operation states (1) to (5) in FIGS. 3 to 7 are repeated, and the alternating voltage V2 is converted into the direct voltage V1.
Note that the frequency of control in the above operating states (1) to (5) is sufficiently higher than the frequency of the AC voltage V2. Therefore, the case where the polarity of the AC voltage V2 is high on the coil L1 side has been described above. When the polarity of the AC voltage V2 is reversed, the direction of the current on the primary side of the transformer TR is reversed. However, in the operation state (3) of FIG. 5, on the secondary side of the transformer TR, a current returns from the intermediate tap of the transformer TR to the secondary side of the transformer TR via the capacitor C0 and the antiparallel diode of the IGBT element T2. Flows. In the figure, a positive voltage is generated at the lower terminal of the secondary side of the transformer TR with respect to the intermediate tap. The direction of the current is such that it flows from the cathode to the anode of the antiparallel diode of the IGBT element T1. Therefore, no current flows through the path of the IGBT element T1. Thus, it can be converted to a DC voltage regardless of the polarity of the AC voltage V2.

The value of the DC voltage V1 can be controlled by adjusting the ratio of the operation period between the operation state (1) in FIG. 3 and the operation state (3) in FIG. 5 according to the magnitude of the AC voltage V2. For example, the conduction time ratio of the IGBT elements T7 and T8 in one cycle of the conduction control of the IGBT elements T5 to T8 is changed with a negative correlation with the voltage peak value of the AC voltage V2. That is, the larger the voltage peak value of the AC voltage V2, the smaller the conduction time ratio of the IGBT elements T7, T8, and the smaller the voltage peak value of the AC voltage V2, the larger the conduction time ratio of the IGBT elements T7, T8. When the IGBT elements T7 and T8 are in a conductive state, electromagnetic energy is accumulated in the coils L1 and L2, the IGBT elements T7 and T8 are non-conductive and the IGBT elements T5 and T6 are in a conductive state, and the AC voltage V2 is equal to the accumulated electromagnetic energy. Is boosted and applied to the primary side of the transformer TR.
That is, the boost is larger as the peak value of the AC voltage V2 is smaller, and the boost is smaller as the peak value of the AC voltage V2 is larger. Since the voltage applied to the transformer TR can be controlled by controlling in this way, the DC voltage V1 is maintained at a substantially constant voltage value with respect to the AC voltage V2 whose voltage peak value changes with time. Can do.

  The operation state (2) in FIG. 4 and the operation state (4) in FIG. 6 are the state transitions between the operation state (1) in FIG. 3 and the operation state (3) in FIG. In order to maintain the continuity of the exciting current of the transformer TR, it is preferable to shorten the period of these operating states as much as possible.

  Also, IGBT elements T7 and T8 that are controlled to store electromagnetic energy in the coils L1 and L2, and IGBT elements that are controlled to send the electromagnetic energy stored in the coils L1 and L2 to the secondary side of the transformer TR. With T5 and T6, conduction / non-conduction is repeated alternately while the conduction periods overlap. As a result, a current path for the coil current IL is always secured, so that a surge voltage due to stored energy does not occur.

  Further, the coil current IL follows the peak value of the AC voltage V2 by controlling the conduction time ratio of the IGBT elements T7 and T8 so as to have a negative correlation with the peak value of the AC voltage V2. The phase of the AC voltage V2 and the coil current IL can be matched, and a good power factor can be realized.

  Next, in the AC / DC converter according to the embodiment shown in FIG. 2, a circuit block diagram in the case where the DC / AC conversion operation is performed by reversing the supply of electric power is shown in FIG. In the circuit shown in FIG. 8, the diode forming the rectifier circuit is a diode connected in reverse parallel to the IGBT elements T1 and T2, and therefore can operate as a DC / AC converter. In the following description, for comparison with the AC / DC conversion operation, the name of each part in the circuit block is unified with the name in the AC / DC conversion operation described in FIG.

  In the rectifier circuit 1, a DC voltage V1 is input with the emitter terminals of the IGBT elements T1 and T2 as the negative side and the intermediate tap of the transformer TR winding as the positive electrode.

  The DC / AC conversion operation will be described below. In the following description, the DC voltage V1 side of the transformer TR is the primary side, and the IGBT elements T5 and T6 side is the secondary side.

  Operation state (6): First, the IGBT elements T5 and T6, which are the first switches, are turned on.

Operation state (7): With the IGBT elements T5 and T6 in the conductive state, the IGBT element T1 (or the IGBT element T2) is in the conductive state, and the DC voltage V1 is applied to the transformer TR on the primary side of the transformer TR. Electric power corresponding to the applied voltage is transmitted through the IGBT elements T5 and T6 and the coils L1 and L2, and a voltage is generated at the output terminal of the AC input circuit 4. At this time, energy is stored in the coils L1 and L2.
At this time, since the IGBT elements T5 and T6 are already conductive, no switching loss occurs.

Operation state (8): Next, the IGBT element T1 is made non-conductive while the IGBT elements T5 and T6 are kept conductive.
Due to the continuity of the exciting current of the transformer TR, a current flows through a path of an intermediate tap, a power supply of the DC voltage V1, an antiparallel diode of the IGBT element T2 which is a rectifier diode (or an antiparallel diode of the IGBT element T1), and the transformer TR.
On the other hand, due to the continuity of the current flowing through the coils L1 and L2, the current continues to flow through a path including the coils L1 and L2, the IGBT elements T5 and T6, and the secondary winding of the transformer TR.

Operation state (9): Next, the IGBT elements T7 and T8, which are the second switches, are made conductive while the IGBT elements T5 and T6 are kept conductive.
Since the secondary winding of the transformer TR is short-circuited by the conduction of the IGBT elements T7 and T8, the exciting current of the transformer TR flows not on the primary side of the transformer TR but on the secondary side. The current flowing through the coils L1 and L2 also flows through the IGBT elements T7 and T8 instead of the IGBT elements T5 and T6.

Operation state (10): Next, the IGBT elements T5 and T6 are set in a non-conductive state while the IGBT elements T7 and T8 are in a conductive state.
Since there is no current path for the secondary winding of the transformer TR, the excitation current flows through the primary winding. The current flowing through the coils L1 and L2 continues to flow through the IGBT elements T7 and T8.
Note that the transformer TR is not excited between the operation state (9) and the operation state (10), and the transformer TR is reset.

Operation state (11): Next, the IGBT elements T5 and T6 are brought into a conducting state while the IGBT elements T7 and T8 are kept in a conducting state.
There is no exciting current, and only the current flowing through the coils L1, L2 continues to flow through the IGBT elements T7, T8.

  Operation state (12): Next, the IGBT elements T5 and T6 are kept in a conducting state, and the IGBT elements T7 and T8 are brought into a non-conducting state. The current flowing through the coils L1 and L2 flows through the IGBT elements T5 and T6 and the secondary side of the transformer TR. Along with this, a voltage is also generated on the primary side of the transformer TR, and a current flows through a path composed of the intermediate tap, the DC voltage V1, and the antiparallel diode of the IGBT element T2 (or the antiparallel diode of the IGBT element T1).

  The operation state (6) to the operation state (12) are repeated as one cycle. The voltage value generated at the terminal of the AC input circuit 4 is adjusted by adjusting the ratio between the time of the operating state (7) and the time of the operating state (10). That is, the voltage value increases when the time of the operation state (7) is longer than the time of the operation state (10), and the voltage value decreases when the time is shorter. The operating states (8) and (9) and the operating states (11), (12), and (1) are operations that maintain the continuity of the current flowing through the coils in the circuit, and should be as short as possible. Is desirable.

  In the above operation, the IGBT element T1 is turned on in the operation state (7) and power is transmitted to the secondary side of the transformer TR. However, if the IGBT element T2 is controlled to be turned on instead of the IGBT element T1, the transformer TR 2 The polarity of the voltage generated on the next side is reversed, and a voltage having the opposite polarity is generated at the terminal of the AC input circuit 4. In other words, alternating current can be generated by switching the period in which the IGBT element T1 is in a conductive state and the period in which the IGBT element T2 is in a conductive state and controlling the polarity of the voltage generated at the terminal of the alternating current input circuit 4.

  For example, according to the frequency of the desired AC voltage, the period for turning on the IGBT element T1 and the period for turning on the IGBT element T2 are switched, and each period is repeated at a frequency sufficiently higher than the frequency of the desired AC voltage. When each IGBT element is operated, an alternating current having a desired voltage waveform can be generated.

  In the above operation, since at least one of the IGBT elements T5 and T6 serving as the first switch and the IGBT elements T7 and T8 serving as the second switch are in a conductive state, a current path flowing through the coils L1 and L2 is ensured. It is possible to prevent the occurrence of surge.

  Further, between the operating state (10) and the operating state (11), a voltage having a polarity opposite to that applied to the transformer TR in the operating state (7) is applied by controlling the IGBT element T2 (or T1). If steps are added, the transformer TR can be surely reset.

  As described above in detail, according to the AC / DC converter and the driving method thereof according to the present embodiment, the AC voltage V2 input from the AC input terminal 20 is supplied to the pair of AC inputs by the conduction of the second switch 3. The electromagnetic energy having a polarity corresponding to the polarity of the AC voltage V <b> 2 is accumulated in the AC input circuit 4 through the circuit input terminal 42. Thereafter, the electromagnetic energy accumulated in the AC input circuit 4 is turned into a pair of AC input circuits as a voltage having a polarity corresponding to the polarity of the AC voltage V2 by the conduction of the first switch 2 and the non-conduction of the second switch 3. The rectifier circuit 1 is supplied from the output terminal 41 via the pair of rectifier circuit input terminals 32, and the DC voltage V <b> 1 is output from the pair of rectifier circuit output terminals 31. In the rectifier circuit 1, the rectifier circuit input end 32 and the rectifier circuit output end 31 are galvanically insulated, and the rectifier is rectified regardless of the voltage having a polarity corresponding to the polarity of the AC voltage V <b> 2 applied to the rectifier circuit input end 32. A DC voltage is output to the circuit output terminal 31. The input AC voltage V2 is changed to a desired DC voltage V1 by alternately conducting the first switch 2 and the second switch 3 through a period in which both the first switch 2 and the second switch 3 are in a conductive state while insulating the input and the output in a DC manner. Can be converted directly.

  Further, the IGBT elements T5, T6, and T7, T8 having anti-parallel diodes are connected in opposite directions with respect to the current path to form the first switch 2 and the second switch 3, respectively. Regardless of the polarity, it is possible to control conduction and non-conduction in both directions.

  In addition, since the IGBT elements T5, T7, T6, and T8 in the AC / DC converter of the embodiment (FIG. 2) are connected to each other, the reference potential at the time of conduction control can be made common. A common drive power supply can be used. It is possible to simplify conduction control and drive power supply.

  Further, according to the AC / DC converter according to the present embodiment, according to the driving method of inputting the DC voltage V1 from the DC output terminal 10 as the output terminal and outputting the AC voltage V2 from the AC input terminal 20 as the input terminal, The voltage applied to the AC input circuit output terminal 41 is smoothed and output to the AC input circuit input terminal 42 by the AC input circuit 4. Appearing at the input terminal 42 of the AC input circuit by adjusting the ratio of the time during which the IGBT elements T5 and T6 which are the first switch 2 and the IGBT elements T7 and T8 which are the second switch 3 are in the conductive state. The waveform of the AC voltage V2 and the magnitude of the voltage value can be controlled. Further, the polarity of the AC voltage V2 appearing at the AC input circuit input terminal 42 can be controlled by changing the polarity of the voltage output to the rectifier circuit input terminal 32. The DC voltage V1 can be directly converted into the desired AC voltage V2 while the input DC voltage V1 and the output AC voltage V2 are isolated in a DC manner.

  The current due to the excitation energy of the transformer TR flows through a closed circuit from the intermediate tap of the secondary side winding to the secondary side winding via the power supply of the DC voltage V1 and the antiparallel diode of the IGBT element T2. The excitation energy of TR is regenerated to the power source of DC voltage V1. The transformer TR is reset when the regenerative operation is completed and the current due to the excitation energy of the transformer TR disappears.

  The present invention is not limited to the above-described embodiment, and it goes without saying that various improvements and modifications can be made without departing from the spirit of the present invention.

  For example, in the present embodiment, as an embodiment of the rectifier circuit 1, a center tap type rectifier circuit that includes an intermediate tap on the secondary side of the transformer TR and includes antiparallel diodes of the IGBT elements T1 and T2 is illustrated. However, the present application is not limited to this. In the circuit block diagram of the first other example of the AC / DC converter shown in FIG. 9, a bridge-type full-wave rectifier circuit is configured as the rectifier circuit 1 by antiparallel diodes of the IGBT elements T <b> 11 to T <b> 14.

  One terminal of the secondary winding of the transformer TR is connected to a connection point between the emitter terminal of the IGBT element T11 and the collector terminal of the IGBT element T13, and the other terminal is connected to the emitter terminal of the IGBT element T12 and the IGBT. A connection point with the collector terminal of the element T14 is connected. The collector terminals of IGBT elements T11 and T12 are commonly connected to the positive electrode of the power source of DC voltage V1, and the emitter terminals of IGBT elements T13 and T14 are commonly connected to the negative electrode of the power source of DC voltage V1. Yes. Each IGBT element is connected with an antiparallel diode. This antiparallel diode constitutes a bridge-type full-wave rectifier circuit. When operating as a DC / AC converter, the polarity of the voltage applied to the secondary winding of the transformer TR is inverted by alternately conducting the IGBT elements T11 and T14 and the IGBT elements T12 and T13. can do.

  Further, the IGBT elements T7 and T8 in the first alternative AC / DC converter (FIG. 9) and the IGBT elements T5 and T6 in the fourth alternative AC / DC converter (FIG. 12) have mutually emitter terminals. Since they are connected, a common reference potential can be used for the conduction control, and a common drive power supply can be used. It is possible to simplify conduction control and drive power supply.

  The rectifier circuit 1 includes IGBT elements T1 and T2 between the secondary winding of the transformer TR and the rectifier circuit output terminal, and a center tap type rectifier circuit is formed by an antiparallel diode of the IGBT elements T1 and T2. The case of configuring has been described. However, in the present invention, it is only necessary to provide a rectifier circuit for rectifying the bipolar voltage output from the transformer TR between the secondary winding of the transformer TR and the rectifier circuit output terminal, and the IGBT element T1. Needless to say, a configuration including a rectifying element such as a diode in the same direction as the anti-parallel diodes of these IGBT elements instead of the T2 and IGBT elements T11 to T14 has the same effects and advantages. Instead of a diode or an antiparallel diode as a rectifier circuit, a synchronous switching operation may be performed using a semiconductor switching element. In this case, loss due to the recovery characteristics of the diode can be suppressed.

  In the present embodiment, the collector terminals of the IGBT elements T7 and T8 are connected, and the emitter terminals of the IGBT elements T5 and T7 and the emitter terminals of the IGBT elements T6 and T8 are connected. Although the case has been described, the present invention is not limited to this.

  For example, the first alternative example of FIG. 9 includes a rectifier circuit 1A instead of the rectifier circuit 1 in the AC / DC converter of the embodiment of FIG. In this configuration, IGBT elements T11 to T14 are provided instead of the IGBT elements T1 and T2. Further, a second switch 3A is provided instead of the second switch 3. The IGBT elements T7 and T8 have a configuration in which the emitter terminals are connected instead of the connection between the collector terminals in the AC / DC converter of the embodiment of FIG. The IGBT elements T7 and T8 are configured to be connected between the emitter terminals. This makes it possible to control conduction and non-conduction in both directions regardless of the polarity of the voltage. Further, since the anti-parallel diodes are opposed to each other, the circuit configuration along with the IGBT elements T5 and T6 is the same as that of the full bridge circuit while the feature that the path through the IGBT elements T7 and T8 can be made non-conductive is ensured. . A general-purpose full bridge driver can be advantageously used for switching control of the IGBT elements T5, T6, T7, and T8. Furthermore, in this case, it is convenient if the emitter terminals of the commonly connected IGBT elements T7 and T8 are set to the installation potential.

  Further, in the second alternative example of FIG. 10, in addition to the AC / DC converter of the embodiment of FIG. 2, the connection point between the emitter terminals of the IGBT elements T6 and T8 is a ground potential, and this connection point and the coil L2 In this configuration, a current sense resistor RS is provided. Thereby, a coil current can always be detected.

  In addition, since the position where the current sense resistor RS is provided is a reference potential at the time of switching control and is fixed in potential, there is no large potential fluctuation due to the operating state. Therefore, it is possible to easily detect a minute voltage detected by the current flowing through the current sense resistor RS.

  In addition, the third alternative example of FIG. 11 includes a first switch 2A and a second switch 3A instead of the first switch 2 and the second switch 3 in the AC / DC converter of the embodiment of FIG. With respect to IGBT elements T5 and T6, the emitter terminals are connected and connected in series, provided between one of the primary windings of transformer TR and coil L2, and the other of the primary winding of transformer TR and the coil L1 is directly connected to L1. As a result, the reference potential for switching control of the IGBT elements T5 and T6 can be used as the emitter terminals connected to each other, and the drive power supply for the switching control can be made common. Switching control and drive power supply can be simplified.

  Also, with regard to the IGBT elements T7 and T8, if the emitter terminals are connected, it is possible to share a drive power source for switching control. Switching control and drive power supply can be simplified.

If the emitter terminals connected to each other are connected to the ground potential, the drive power supply can be configured with the ground potential as the reference potential.

  The IGBT elements T1, T2, and T11 to T14 as rectifiers of the rectifier circuits 1 and 1A all include anti-parallel diodes, and the anti-parallel diodes constitute a center tap rectifier circuit or a bridge-type full-wave rectifier circuit. It is not limited to the configuration. A center tap type rectifier circuit or a bridge type full-wave rectifier circuit may be configured by including only a diode.

It is a circuit block diagram which shows the AC / DC converter of this invention. It is a circuit block diagram in the case of performing an alternating current direct current conversion operation in the alternating current direct current converter of an embodiment. It is a figure which shows the operation state (1) in AC / DC conversion operation | movement. It is a figure which shows the operation state (2) in AC / DC conversion operation | movement. It is a figure which shows the operation state (3) in AC / DC conversion operation | movement. It is a figure which shows the operation state (4) in AC / DC conversion operation | movement. It is a figure which shows the operation state (5) in AC / DC conversion operation | movement. It is a circuit block diagram in the case of performing DC / AC conversion operation in the AC / DC converter of the embodiment. It is a circuit block diagram which shows the 1st another example of an alternating current direct current converter. It is a circuit block diagram which shows the 2nd another example of an alternating current direct current converter. It is a circuit block diagram which shows the 3rd another example of an alternating current direct current converter. It is a circuit block diagram of background art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rectifier circuit 2 1st switch 3 2nd switch 4 AC input circuit 10 DC output terminal 20 AC input terminal 31 Rectifier circuit output terminal 32 Rectifier circuit input terminal 41 AC input circuit output terminal 42 AC input circuit input terminal L1, L2 Coil T1 , T2, T5 to T8 IGBT element TR transformer V1 DC voltage V2 AC voltage

Claims (12)

A pair of AC input terminals to which an AC voltage is input;
A pair of DC output terminals from which a DC voltage is output;
AC input circuit,
A rectifier circuit;
A first switch;
A second switch,
The AC input circuit includes a pair of AC input circuit input ends, a pair of AC input circuit output ends, and at least one inductance element provided in a path from the AC input circuit input end to the AC input circuit output end. Have
The rectifier circuit includes a pair of rectifier circuit input ends, a pair of rectifier circuit output ends, a transformer connected to the rectifier circuit input end, and a rectifier provided between the transformer and the rectifier circuit output end. Have
The AC input terminal and the AC input circuit input terminal are connected, the AC input circuit output terminal and the rectifier circuit input terminal are connected via the first switch, the rectifier circuit output terminal and the DC output terminal Are connected, and the second switch is connected between the output terminals of the AC input circuit. The first switch includes two semiconductor switching elements having anti-parallel diodes,
One of the switching elements is interposed between one of the pair of AC input circuit output ends and one of the pair of rectifier circuit input ends so that an emitter or a source is connected to the one AC input circuit output end. And
The other one of the switching elements is connected between the other of the pair of AC input circuit output ends and the other of the pair of rectifier circuit input ends so that an emitter or a source is connected to the other AC input circuit output end. The AC / DC converter according to claim 1, wherein the AC / DC converter is interposed in the AC. The second switch includes two semiconductor switching elements having antiparallel diodes,
The AC / DC converter according to claim 2, wherein the two semiconductor switching elements constituting the second switch are connected in series with their emitters or sources connected to each other. The second switch includes two semiconductor switching elements having antiparallel diodes,
The AC / DC converter according to claim 2, wherein the two semiconductor switching elements constituting the second switch are connected in series with their collectors or drains connected.   A connection point between one emitter or source of the semiconductor switching element constituting the first switch and the emitter or source of the semiconductor switching element constituting the second switch connected to the emitter or source, and the AC input circuit 5. The AC / DC converter according to claim 4, wherein a current sense resistor is interposed between one of the output terminals. The first switch includes two semiconductor switching elements having anti-parallel diodes, and the two semiconductor switching elements constituting the first switch are connected in series with their emitters or sources connected to each other,
The first switch is interposed between one of the pair of AC input circuit output ends and one of the pair of rectifier circuit input ends,
The other of the pair of AC input circuit output ends and the other of the pair of rectifier circuit input ends are directly connected,
The second switch includes two semiconductor switching elements having anti-parallel diodes, and the two semiconductor switching elements constituting the second switch are connected in series with their emitters or sources connected to each other. The AC / DC converter according to claim 1, wherein:   The AC / DC converter according to claim 3 or 6, wherein emitters or sources connected to each other of two semiconductor switching elements constituting the second switch are connected to a ground potential.   The rectifying unit includes a semiconductor switching element having an antiparallel diode, and the antiparallel diode constitutes either a center tap rectifier circuit or a bridge type full-wave rectifier circuit. The AC-DC converter described. An AC input circuit including an inductance element to which an AC voltage is applied;
A rectifying circuit that galvanically isolates the bipolar voltage and converts it into a DC voltage;
A first switch provided between the rectifier circuit and the alternating current input circuit and configured to interrupt current;
An AC / DC converter having a second switch for short-circuiting and opening the first switch side of the AC input circuit. A pair of AC input terminals to which an AC voltage is input;
A pair of DC output terminals from which a DC voltage is output;
AC input circuit,
A rectifier circuit;
A first switch;
A second switch,
The AC input circuit includes a pair of AC input circuit input ends, a pair of AC input circuit output ends, and at least one inductance element provided in a path from the AC input circuit input end to the AC input circuit output end. Have
The rectifier circuit includes a pair of rectifier circuit input ends, a pair of rectifier circuit output ends, a transformer connected to the rectifier circuit input end, and a rectifier provided between the transformer and the rectifier circuit output end. Have
The AC input terminal and the AC input circuit input terminal are connected, the AC input circuit output terminal and the rectifier circuit input terminal are connected via the first switch, the rectifier circuit output terminal and the DC output terminal Is connected to the AC input circuit, and the second switch is connected between the output terminals of the AC input circuit, and converts the AC voltage to output the DC voltage.
The method for driving an AC / DC converter, wherein the first switch and the second switch are alternately turned on after a period in which they are both turned on.   The ratio of time during which the second switch conducts in the conduction period of the first and second switches is controlled to have a negative correlation with the peak value in the AC voltage. The drive method of the alternating current converter of 10. Step 1: conducting the first switch under the conducting state of the second switch;
Step 2: making the second switch non-conductive under the conductive state of the first switch;
Step 3: conducting the second switch under the conducting state of the first switch;
Step 4: making the first switch non-conductive under the conductive state of the second switch,
The method for driving an AC / DC converter according to claim 11, wherein the steps 1 to 4 are repeated.

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