JP6241253B2 - Resonant inverter device - Google Patents

Description

  The present invention relates to a resonant inverter device of soft switching control that converts direct current into alternating current or alternating current into direct current.

  FIG. 8 is a circuit diagram showing Example 1 of a conventional resonant inverter device (Patent Document 1). The resonance type inverter device shown in FIG. 8 has a soft switching circuit system in which a booster circuit 1, an auxiliary circuit 2, and an inverter circuit 3 are connected between DC bus lines PN, and the inverter circuit 3 and the distribution system are interconnected by a filter circuit 4. . The auxiliary circuit 2 is operated at the timing when the switches Qo and S1 to S4 of the booster circuit 1 and the inverter circuit 3 are turned on, and the switches Qo and S1 to S4 are turned on at zero voltage.

  The switches Qo, S1 to S4 are turned off, and the rise of the voltage is delayed by the capacitors Co, C1 to C4 connected in parallel to the switches Qo, S1 to S4, and the switches Qo and S1 to S4 are turned off. With this method, since the switching loss generated in the switches Qo, S1 to S4 is reduced, the efficiency can be greatly improved.

  However, when the power of the DC power source E is regenerated to the AC system, the booster circuit 1 always operates regardless of the magnitude of the voltage of the DC power source E. For this reason, the booster circuit 1 operates even when the voltage of the DC power source E is larger than the DC bus voltage necessary for generating the AC voltage. For this reason, the boost circuit 1 has a problem that loss occurs and conversion efficiency deteriorates.

  As a solution to this problem, techniques described in Patent Document 2 and Patent Document 3 are known. FIG. 9 is a circuit diagram showing Example 2 of a conventional inverter device (Patent Document 2). FIG. 10 is a circuit diagram showing Example 3 of a conventional inverter device (Patent Document 3). The inverter device shown in FIGS. 8 and 9 is composed of a hard-switching system interconnection inverter.

  In FIG. 9, when the DC bus voltage V3B necessary for generating the AC voltage is Vm1 and the solar voltage Vo is smaller than Vm1, the IGBT switch 103a is turned on and off to boost it to Vm1, and the solar voltage Vo is When Vm1 is exceeded, the IGBT switch 103a is stopped. As the solar voltage Vo increases, the step-up rate decreases to improve the efficiency of the chopper circuit 103. However, when the IGBT switch 103a is stopped, the loss is greatly reduced, and only the conduction loss of the diode 103c is achieved. Therefore, the efficiency increases abruptly at the boundary of the solar voltage Vo at Vm1.

  In FIG. 10, the IGBT switch 103a is turned on / off until the sunlight voltage Vo reaches a predetermined voltage Vm1, and the voltage is boosted to Vm1. During this time, the bypass circuit 107 is open. When the sunlight voltage Vo exceeds the predetermined voltage Vm1, the IGBT switch 103a is stopped. At this time, the relay 107a of the bypass circuit 107 is closed and a current is supplied to the bypass circuit 107 side, thereby bypassing the reactor 103b and the diode 103c of the chopper circuit 103. When the solar voltage Vo exceeds Vm1, the boosting operation is stopped, so that there is almost no loss. For this reason, the efficiency of the solar voltage Vo suddenly increases with Vm1 as a boundary.

JP 2012-23831 A JP 2006-238628 A JP 2006-238629 A

  However, in the conventional resonance type inverter, when the booster circuit is simply stopped and bypassed, the voltage between the DC buses PN is reduced to zero at the resonance timing, so that the boost reactor L1 is unnecessarily excited by the DC voltage E. The system may not work stably.

  Even when a storage battery or the like is connected to the DC voltage (Ca + Cb) shown in FIG. 8 and only the inverter circuit 3 is operated to charge the storage battery from the AC system, the boost reactor L1 is unnecessarily excited at the resonance timing. The system will behave unintentionally.

  An object of the present invention is to provide a resonance type inverter device in which a step-up reactor is not excited unnecessarily, the system is stabilized, and high efficiency can be realized.

  In order to solve the above-described problems, the present invention is connected to a DC voltage and includes a first series circuit including a first reactor and a first switch, and includes the first switch, a first rectifying element, and a second switch. A booster converter that boosts the input DC voltage, and a third series circuit that is connected to both ends of the second series circuit and includes a third switch, a first capacitor, and a second capacitor. A fourth series circuit comprising a fourth switch and a second rectifier element connected to both ends of the second series circuit, a connection point between the first capacitor and the second capacitor, the fourth switch, and the second An auxiliary circuit having a second reactor connected between a connection point with the rectifying element, a connection point between the first switch and the first rectifying element, and a connection between the third switch and the first capacitor. Between the dots A third rectifying element connected; an inverter circuit connected to the auxiliary circuit and having a plurality of main switches connected in a bridge; and a control circuit for turning on and off the first to fourth switches and the plurality of main switches. It is characterized by that.

  According to the present invention, in the mode in which the booster circuit is stopped and only the resonant inverter circuit is operated, the booster reactor is not excited unnecessarily by the second switch and the third rectifying element, the system is stabilized, and high efficiency is realized. A resonance type inverter device that can be provided can be provided.

It is a circuit diagram which shows the resonance type inverter apparatus of Example 1 of this invention. It is a figure which shows the equivalent circuit for one phase of the inverter provided in the resonance type inverter apparatus of Example 1. FIG. 6 is an operation waveform diagram of each part in the booster circuit stop mode of the resonant inverter device according to the first embodiment. FIG. 6 is an operation waveform diagram of each part in a booster circuit operation mode of the resonance type inverter device of the first embodiment. It is a circuit diagram which shows the resonance type inverter apparatus of Example 2 of this invention. It is a circuit diagram which shows the resonance type inverter apparatus of Example 3 of this invention. It is a circuit diagram which shows the resonance type inverter apparatus of Example 5 of this invention. It is a circuit diagram which shows Example 1 of the conventional resonance type inverter apparatus. It is a circuit diagram which shows the example 2 of the conventional inverter apparatus. It is a circuit diagram which shows Example 3 of the conventional inverter apparatus.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a resonant inverter device of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a circuit diagram showing a resonant inverter device according to a first embodiment of the present invention. In the resonance type inverter device of the first embodiment, in the mode in which the booster circuit 1a is stopped and only the inverter circuit 3 is operated, the booster reactor L1 is not excited unnecessarily, and only the inverter circuit 3 performs zero voltage switching by resonance. A switch Q3 and a diode Dd are added to the booster circuit 1a.

  Further, in the mode in which both the booster circuit 1a and the inverter circuit 3 are operated by controlling the added switch Q3, the booster circuit 1a and the inverter circuit 3 perform zero voltage switching by resonance at once. And

  In FIG. 1, a booster circuit 1a is connected to both ends of a DC power supply E. The booster circuit 1a includes a series circuit (first series circuit) of a booster reactor L1 connected to both ends of a DC power source E and a switch Qo (first switch) composed of an insulated gate bipolar transistor (IGBT), and a switch Qo. And a series circuit (second series circuit) of a diode Dc (first rectifying element) and a switch Q3 (second switch) made of IGBT, and boosts the voltage of the DC power supply E.

  A diode Do and a capacitor Co are connected in parallel between the collector and emitter of the switch Qo.

  The auxiliary circuit 2 is connected to both ends of the second series circuit of the booster circuit 1a through a positive input line P and a negative input line N. The auxiliary circuit 2 is configured as follows. A series circuit (third series circuit) composed of an IGBT switch Q1 (third switch), a capacitor Ca (first capacitor), and a capacitor Cb (second capacitor) is connected to both ends of the second series circuit of the booster circuit 1a. Has been.

  Further, a series circuit of a switch Q2 (fourth switch) made of an IGBT and a diode Ds (second rectifier element) is connected to both ends of the second series circuit of the booster circuit 1a.

A reactor Lr (second reactor) is connected between a connection point between the capacitor Ca and the capacitor Cb and a connection point between the switch Q2 and the diode Ds. A connection point between the switch Qo and the diode Dc and a connection point between the switch Q1 and the capacitor Ca are connected via a diode Dd (third rectifier element).

  A diode Da is connected in parallel between the collector and emitter of the switch Q1, and a diode Db is connected in parallel between the collector and emitter of the switch Q2.

  An inverter circuit 3 is connected between the positive input line P and the negative input line N. In the inverter circuit 3, a series circuit (half-bridge circuit) of the main switch S1 and the main switch S2 is connected between the positive input line P and the negative input line N, and the main switch S3 and the main switch A series circuit (half-bridge circuit) with S4 is connected. Diodes D1 to D4 and resonant capacitors C1 to C4 are connected between collectors and emitters of main switches S1 to S4 made of IGBT.

  The connection point between the main switch S1 and the main switch S2 is connected to the AC output terminal W1 via the reactor Lw, and the connection point between the main switch S3 and the main switch S4 is connected to the AC output terminal U1 via the reactor Lu. A connection point between the auxiliary capacitor Ca and the auxiliary capacitor Cb is connected to the AC output terminal V1. Here, the filter circuit 4 is composed of reactors Lu and Lw and capacitors C11 and C12, and is a filter that removes high frequency components and outputs a sine wave component.

  The control circuit 10a performs on / off control of the switches Qo, Q1, Q2, and Q3 so that the voltages of the capacitors Co, C1 to C4 become zero voltage when the main switches Qo and S1 to S4 are turned on, and the main switches Qo and S1. ˜S4 is switched to zero voltage.

  At this time, when stopping the boosting operation of the booster circuit 1a, the control circuit 10a turns off the switch Qo and the switch Q3 and turns on and off the switch Q1 and the switch Q2.

  Further, when operating the booster circuit 1a and the inverter circuit 3, the control circuit 10a always turns on the switch Q3 and turns on and off the switches Q1 and Q2.

  Next, the operation of the resonance type inverter device of the first embodiment configured as described above will be described with reference to an equivalent circuit for one phase of the inverter shown in FIG.

  In the circuit configuration of FIG. 1, it is assumed that the currents of the step-up reactor L1 and the AC reactors Lu and Lw do not change during the several usec period at the time of resonance, and in FIG. 2, the constant current sources Id and Io are described. For the sake of simplicity, only one phase of the inverter circuit is handled as shown in FIG.

  FIG. 3 shows the control timing and operation mode when the booster circuit 1a is stopped and only the inverter circuit 3 is operated. FIG. 4 shows a control timing and an operation mode when the booster circuit 1a and the inverter circuit 3 are operated.

  First, the operation when the booster circuit 1a is stopped and only the inverter circuit 3 is operated will be described with reference to FIG. 3 and 4, G (Q1) is the gate signal of the switch Q1, G (Q2) is the gate signal of the switch Q2, G (Q3) is the gate signal of the switch Q3, and G (S3) is the main switch S3. , G (S4) is the gate signal of the main switch S4, G (Qo) is the gate signal of the switch Qo, I (Lr) is the current flowing through the reactor Lr, V (PN) is the voltage between the DC buses PN, V (S3) is the collector-emitter voltage of the main switch S3, I (S3sw) is the collector current flowing through the main switch S3, V (Qo) is the collector-emitter voltage of the switch Qo, and I (Qosw) is flowing through the switch Qo. Collector current.

  First, when stopping the booster circuit 1a, the control circuit 10a always turns off the switch Qo and the switch Q3 by the gate signal G (Qo) and the gate signal G (Q3).

  In the period t2, when the switch Q1 is turned off and the switch Q2 is turned on, the electric charge of the capacitor C3 is discharged, and the current I (Lr) flows through the reactor Lr through the path C3 → Q2 → Lr → Cb → D4 → C3. At this time, the current I (Lr) becomes a sinusoidal current due to resonance between the reactor Lr, the capacitor C3, and the capacitor Cb. Further, the current Id flowing from the DC power source E is output to the capacitor Ca and the capacitor Cb through a route of Dd → Ca → Cb.

  In the period t3, when the discharge of the charge of the capacitor C3 is completed, the voltage V (S3) of the switch S3 becomes zero voltage, and the current I (Lr) becomes zero, the main switch S3 is turned on. Thereby, the zero voltage switching of the main switch S3 can be realized.

  Similarly to the voltage V (S3) of the switch S3, the voltage V (PN) between the DC buses PN also decreases from the voltage of the DC power supply E to zero due to resonance. However, since the switch Q3 is off, the voltage V (Qo of the switch Qo ) Is a constant value of the voltage of the DC power supply E. Therefore, the boost reactor L1 is not unnecessarily excited by the voltage of the DC power source E.

  Further, the negative current I (Lr) starts to flow through the path of Cb → Lr → Db → S3 → C4 → Cb. The current I (Lr) and the current I (S3) are sinusoidal currents due to resonance between the reactor Lr and the capacitor C4.

  In the period t4, the capacitor C4 is charged by the resonance current, and the voltage of V (S4) increases. In the period t4, the switch Q2 is turned off, but the resonance current flows through the diode Db. Then, when the resonance ends at the end of the period t4, that is, at the start of the period t5, the switch Q1 is turned on.

  Next, a case where the booster circuit 1a and the inverter circuit 3 are operated will be described with reference to FIG.

  The control circuit 10a always turns on the switch Q3 by the gate signal G (Q3).

  In the period t0, the current Id flows through the first path Dd → Ca → Cb and the second path Dc → Q3 → Da → Ca → Cb. By turning on the switch Q2 in the period t1, the current Id flowing through the diode Da and the diode Dd is commutated to the reactor Lr.

  When the current I (Lr) of the reactor Lr reaches the current Id, the commutation is completed, and a period t2 in which the charges of the capacitor C3 and the capacitor Co are discharged. The discharge path of the capacitor C3 is C3-> Q2-> Lr-> Cb-> D4-> C3, and the discharge path of the capacitor Co is Co-> Dc-> Q3-> Q2-> Lr-> Cb-> Co.

  In the period t2, when the discharge of the charges of the capacitors Co and C3 is completed, the capacitor Co voltage V (Qo) and the voltage V (S3) of the capacitor C3 become zero voltage, and the current I (Lr) becomes Id. The main switches Qo and S3 are turned on. Thereby, the zero voltage switching of the main switches Qo and S3 can be realized.

  In the period t3, the negative current I (Lr) starts to flow through the path of Cb → Lr → Q2 → S3 → C4 → Cb. The current I (Lr) and the current I (S3) are sinusoidal currents due to resonance between the reactor Lr and the capacitor C4.

  In the period t4, the capacitor C4 is charged by the resonance current, and the voltage V (S4) increases. Although the switch Q2 is turned off, a resonance current flows through the diode Db.

  Then, when the resonance ends at the end of the period t4, that is, at the start of the period t5, the switch Q1 is turned on. When current I (Lr) of reactor Lr rises to zero, diode Db of switch Q2 reversely recovers at the start of period t6. The energy accumulated in the reactor Lr by the reverse recovery is regenerated to the capacitor Cb through a path of Lr → Cb → Ds → Lr. During this period, the voltage V (Q2) of the switch Q2 is clamped to the combined voltage of the capacitors Ca and Cb. That is, the output voltage of the booster circuit 1 is clamped.

  The energy accumulated in the reactor Lr is regenerated in the capacitor Cb, so that the high-frequency vibration between the current I (Lr) of the reactor Lr and the voltage V (Q2) of the switch Q2 can be suppressed in the period t6. Even when the switching of the switch Q2 to the turn-off shifts after the period t6 and energy is accumulated in the reactor Lr, the operation is the same as that described above.

  Thus, according to the resonance type inverter device of the first embodiment, in the mode in which the booster circuit 1a is stopped and only the inverter circuit 3 is operated, the booster reactor L1 is not excited unnecessarily, and only the inverter circuit 3 is switched to zero voltage by resonance. Can stabilize the system and achieve high efficiency.

  Further, in the mode in which both the booster circuit 1a and the inverter circuit 3 are operated, the booster circuit 1a and the inverter circuit 3 can perform zero voltage switching at once, so that a highly efficient converter can be realized even when boosting is necessary. .

  FIG. 5 is a circuit diagram showing a resonant inverter device according to the second embodiment of the present invention. The resonant inverter device according to the second embodiment has a configuration of the resonant inverter device according to the first embodiment shown in FIG. 1 and further includes a connection point between the switch Q1 and the capacitor Ca and a positive electrode of the voltage of the DC power supply E with a diode Df ( The fourth rectifier element) is connected.

  As described above, according to the resonant inverter device of the second embodiment, when the booster circuit 1a is stopped and only the inverter circuit 3 is operated, and the switches Qo and Q3 are turned off, E → Df → Ca → Cb → E In this way, the voltage of the DC power source E is output to the capacitors Ca and Cb.

  That is, since the reactor L1 is bypassed, the loss of the reactor L1 can be reduced.

  FIG. 6 is a circuit diagram showing a resonant inverter device according to the third embodiment of the present invention. The resonance type inverter device of the third embodiment has a diode Df (a connection point between the switch Q1 and the capacitor Ca and a positive electrode of the voltage of the DC power supply E in addition to the configuration of the resonance type inverter device of the first embodiment shown in FIG. The fourth rectifier element is connected via an IGBT switch Q4 (fifth switch).

  In the resonance type inverter device according to the second embodiment, since only the diode Df is present, when there is no electric charge in the capacitor Ca and the capacitor Cb, an inrush current flows from the voltage of the DC power source E to the capacitor Ca and the capacitor Cb via the diode Df. Flows.

  For this reason, in the resonance type inverter device of the third embodiment, when there is no electric charge in the capacitor Ca and the capacitor Cb, the control circuit 10b turns off the switch Q4.

  At this time, the voltage of the DC power source E is output to the capacitors Ca and Cb through the path of E → L1 → Dd → Ca → Cb → E. Then, when the capacitor Ca and the capacitor Cb are sufficiently charged, the control circuit 10b turns on the switch Q4.

  Then, the voltage of the DC power source E is output to the capacitors Ca and Cb through a path of E → Df → Q4 → Ca → Cb → E, but a slight current flows through the diode Df. That is, the diode Df can be protected from the inrush current by inserting the switch Q4.

  In the fourth embodiment, the first capacitor Ca of the first embodiment is replaced with a first storage battery, and the second capacitor Cb is replaced with a second storage battery. When energy is output only from the first storage battery and the second storage battery, the switches Q0 and Q3 are always turned off, and the switches Q1 and Q2 and the switches S1 to S4 of the inverter circuit 3 are turned on and off. Thereby, AC power can be output from the inverter circuit 3 with power from the storage battery without exciting the step-up reactor L1 unnecessarily.

  In addition, when charging the first storage battery and the second storage battery from the AC terminal, the switch Q0 and the switch Q3 are always turned off, and the switches Q1 and Q2 and the switches S1 to S4 of the inverter circuit 3 are turned on and off to increase the voltage. The storage battery can be charged without unnecessarily exciting the reactor L1.

  FIG. 7 is a circuit diagram showing a resonance type inverter apparatus according to Embodiment 5 of the present invention. In the fifth embodiment, the storage battery 11 is further connected to the capacitors Ca and Cb via the bidirectional DC / DC converter 12. Capacitors Ca and Cb are charged by boost converter 1 a and also charged from storage battery 11 via bidirectional DC / DC converter 12.

For this reason, not only the electric power from the boost converter 1a is supplied to the electric power system by the inverter circuit 3, but also the electric power from the storage battery 11 can be supplied to the electric power system by the inverter circuit 3. It is also possible to charge the storage battery 11 through the bidirectional DC / DC converter 12 with the charging energy charged in the capacitors Ca and Cb by the boost converter 1a.

  In the fifth embodiment, the boost converter 1a can be stopped and the inverter circuit 3 can be operated only by the electric power from the storage battery 11 without unnecessarily exciting the boost reactor L1 as in the first embodiment.

  At this time, the control circuit 10b always turns off the switch Q0 and the switch Q3, and turns on and off the switches Q1 and Q2 and the switches S1 to S4 of the inverter circuit 3 as in the case of stopping the boost converter 1a of the first embodiment. Therefore, the inverter circuit 3 can be operated only with the electric power from the storage battery 11 without exciting the step-up reactor L1 unnecessarily.

  Further, even when charging the storage battery 11 from the AC terminal, the switch Q0 and the switch Q3 are always turned off, and the switches Q1 and Q2 and the switches S1 to S4 of the inverter circuit 3 are turned on and off so that the boost reactor L1 is unnecessary. The storage battery 11 can be charged without being excited.

  The storage battery 11 may rectify the power from the power system and charge it via the bidirectional DC / DC converter 12. Further, the storage battery 11 may be charged with power from a distributed power source 13 such as a solar power generation device via a bidirectional DC / DC converter 12. The fifth embodiment has the same effect as the circuits of the second and third embodiments.

  The present invention is applicable to a DC-AC power converter and a grid interconnection inverter.

E DC power supply L1 Boost reactors Qo, Q1, Q2, Q3 Switches S1-S4 Main switch
Lr reactors Da, Db, Dc, Ds, Do to D4 Diodes Ca, Cb, Co to C4, C11, C12 Capacitor Lu, Lw Reactor 1a Booster circuit 2 Auxiliary circuit 3 Inverter circuit 4 Filter circuits 10, 10a, 10b Control circuit 11 Storage battery 12 Bidirectional DC / DC converter 13 Power system or distributed power supply

Claims (8)

A first series circuit comprising a first reactor and a first switch, and a second series circuit comprising a first switch, a first rectifier element and a second switch, connected between the DC voltages, A boost converter that boosts a DC voltage;
A third series circuit composed of a third switch, a first capacitor, and a second capacitor, connected to both ends of the second series circuit; connected to both ends of the second series circuit; a fourth switch; a second rectifying element; And an auxiliary circuit having a second reactor connected between a connection point between the first capacitor and the second capacitor and a connection point between the fourth switch and the second rectifier element. When,
A third rectifying element connected between a connection point of the first switch and the first rectifying element and a connection point of the third switch and the first capacitor;
An inverter circuit connected to the auxiliary circuit and bridge-connecting a plurality of main switches;
A control circuit for turning on and off the first to fourth switches and the plurality of main switches;
A resonance type inverter device comprising:   The control circuit turns off the first switch and the second switch and turns on and off the third switch and the fourth switch when stopping the boosting operation of the boost converter, thereby setting the main switch to zero voltage. 2. The resonance type inverter device according to claim 1, wherein switching is performed.   When operating the boost converter and the inverter circuit, the control circuit turns on the second switch, and turns on and off the third switch and the fourth switch, so that the main switch and the first switch are turned on. 3. The resonant inverter device according to claim 1, wherein the switch is zero-voltage switched.   4. The resonance according to claim 1, wherein a connection point between the third switch and the first capacitor and a positive electrode of the DC voltage are connected via a fourth rectifier element. 5. Type inverter device.   The connection point between the third switch and the first capacitor and the positive electrode of the DC voltage are connected via a fourth rectifier element and a fifth switch. A resonance type inverter device according to item 1.   6. The resonant inverter device according to claim 1, wherein the first capacitor is a first storage battery, and the second capacitor is a second storage battery.   A bidirectional DC / DC converter is connected to both ends of a series circuit composed of the first capacitor and the second capacitor, and a third storage battery is connected to the other of the bidirectional DC / DC converter. The resonance type inverter device according to any one of claims 1 to 5.   8. The resonant inverter device according to claim 7, wherein the third storage battery is charged by electric power obtained by rectifying an electric power system or direct-current electric power from a distributed power source.

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