JP4834865B2 - Bidirectional buck-boost chopper circuit - Google Patents

Description

  The present invention relates to a bidirectional buck-boost chopper circuit, and more particularly to reduction of switching loss.

  For driving an electric vehicle such as a fuel cell vehicle, a high-efficiency, high-power chopper circuit that operates in an output range of 100 kW is used. Conventionally, hard switching converters are used in the field of electric vehicles.

  Conventionally, a step-up chopper circuit and a step-down chopper circuit that perform voltage step-up and step-down using a reactor are known. In this step-up operation using a reactor, DC power is accumulated in the reactor by turning on and off switching elements such as transistors at high speed, and boosting is performed by outputting this DC power. In step-down operation, DC power is accumulated in the reactor by turning on and off switching elements such as transistors at high speed, and step-down is performed by circulating this DC power through a diode. The step-up / down chopper circuit is configured by combining the step-up chopper circuit and the step-down chopper circuit.

  As the operation of these switching elements, a hard switching method and a soft switching method are known. In the hard switching system, there is a problem that power loss is large because the time during which the transient voltage and the transient current cross each other is long when the switching element is turned on or turned off. This switching loss increases as the switching frequency increases. For example, Patent Document 1 is known as a fuel cell circuit using a hard switching system.

  On the other hand, in the soft switching system, the power loss is reduced by performing the switching operation in a state where the voltage or current is zero using a resonance phenomenon or the like. Low loss is required not only in fuel cell vehicles but also in the field of using semiconductor power conversion devices, so a chopper circuit by soft switching is required.

  Conventionally, a C bridge chopper circuit is known as a high power chopper circuit (for example, Patent Document 2). The C-bridge chopper circuit has, for example, a configuration using two switches and one capacitor, and is suitable for high-current applications because it can cut off a large current by a lossless snubber circuit and is lossless.

  However, this C-bridge chopper circuit has a problem that the overall power loss is large because the main switch and the diode are connected in series to the main circuit, and when two main switches connected by a capacitor are turned on simultaneously. The overvoltage generated by the recovery current at the time of reverse recovery of the output diode and the charging voltage of the snubber capacitor are superimposed, which causes a problem that a large overvoltage is generated and the output diode may be damaged.

  Accordingly, the inventors of the present application have proposed a quasi-resonant regenerating active snubber (QRAS) type chopper circuit (see, for example, Non-Patent Document 1 and Patent Document 3). In the QRAS chopper circuit, a main switch and an auxiliary switch are provided and a reactor is connected in series to the main switch so that the current flowing through the main switch is delayed so that the current becomes zero when the main switch is turned on.

JP 2002-63923 A JP 2004-274877 A JP 2005-261124 A Proceedings of the Conference of the Institute of Electrical Engineers of Japan, Tsuruma, Kamigami, Kawamura “High-efficiency, high-power chopper circuit QRAS” 2004-6

  In the above-mentioned QRAS chopper circuit, soft switching is realized by connecting a reactor to the main switch. However, there is a problem that conversion efficiency is reduced due to heat loss generated by internal resistance caused by current flowing through the reactor.

  There is also a problem that the main switch also generates an overcurrent overvoltage when the main switch of the QRAS chopper circuit is turned on and off. The turn-off overvoltage of the main switch is generated by applying a snubber capacitor clamp voltage to the main switch. There is also a problem that when the main switch is turned on, an excessive current flows through the main switch due to reverse recovery of the output diode.

  In addition, there is a problem that a large reverse spike voltage is generated in the output diode due to reverse recovery of the output diode, and the output diode itself may be damaged.

  As described above, in the conventionally proposed chopper circuit that performs switching operation by soft switching, (a) the problem of heat loss caused by the current flowing through the reactor, (b) when the main switch is turned on and off, or output There are various problems such as overcurrent overvoltage of the main switch due to reverse recovery of the diode and damage to the main switch and output diode due to reverse spike voltage of reverse recovery of the output diode.

  In order to drive a fuel cell electric vehicle with high efficiency, it is necessary to perform bidirectional buck-boost power conversion between the fuel cell, the secondary battery, and the motor as a load. Here, the bidirectional means the direction from the power source to the load and the direction of regeneration from the load to the power source side. When the load of a fuel cell electric vehicle or the like fluctuates variously, the voltage relationship between the power supply side and the load side also changes variously, and boosting and stepping down may occur in both directions.

Therefore, in the bidirectional buck-boost chopper circuit, the step-up operation from the power source side to the load side, the step-down operation from the power source side to the load side, the step-up operation from the load side to the power source side, and the step-down operation from the load side to the power source side are performed. It is required to perform four power conversion operations. When a bidirectional buck-boost chopper circuit is configured using a chopper circuit composed of a main switch and a reactor, for example, a circuit configuration shown in FIG. 11 is assumed. In the circuit configuration of FIG. 11, an example is shown in which the bidirectional buck-boost chopper circuit is configured by forming a bridge with _four main switches S _{1 to} S ₄ with one reactor L ₁ interposed. In this configuration example, when the switching operation is performed by hard switching, there is a problem that the power loss is large as described above.

  Further, even when a bidirectional buck-boost chopper circuit is configured using the above-described chopper circuit that performs soft switching, each chopper circuit has the above-described problems of heat loss and element damage.

  Therefore, there is a need for a bidirectional buck-boost chopper circuit with low loss and high reliability, but a bidirectional buck-boost chopper circuit with low loss and high reliability as currently required has been proposed. Not.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described conventional problems, to reduce the loss of the bidirectional buck-boost chopper circuit, and to suppress overvoltage and overcurrent.

  Moreover, it aims at reducing the heat loss which generate | occur | produces in a reactor by soft switching operation, and improving conversion efficiency.

  It is another object of the present invention to prevent overcurrent overvoltage when the main switch is turned on.

  Another object of the present invention is to prevent overvoltage due to reverse recovery of the output diode.

  The bidirectional buck-boost chopper circuit of the present invention is a bidirectional buck-boost chopper circuit that performs a boost operation and a buck operation bidirectionally between a first terminal and a second terminal. Alternatively, four electrically equivalent chopper sections that perform a step-down operation are provided.

  Each of the four chopper units constitutes a snubber-assisted ZVZCT (Snubber-Assisted Zero Voltage and Zero Current Transition chopper) chopper unit with the following configuration. Each chopper unit is equivalent to three main reactors constituting one reactor, and one pole is connected to one end of the series connection body of the main reactor, and the other pole is directly connected to one voltage terminal of the DC power source. The main switch connected to the main switch, the series connection of the snubber diode and the snubber capacitor connected between the poles of the main switch, the connection point of the snubber diode and the snubber capacitor, and the connection point of the series connection of the two main reactors And an auxiliary switch connected between them.

  In order to make the current at the time of turning on the main switch zero, a reactor is conventionally used, whereas the chopper unit provided in the bidirectional buck-boost chopper circuit of the present invention is provided with an auxiliary switch. To do. By turning on this auxiliary switch, the voltage of the snubber capacitor is set to zero voltage, the voltage at the time of turning on the main switch is set to zero voltage, and a regenerative resonance between the snubber capacitor and the main reactor is generated via the auxiliary switch. When the zero voltage is reached, the main switch is turned on, and the current due to the regenerative resonance is caused to flow in a direction to cancel the main current of the main switch, so that the current and voltage of the main switch at the time of turn-on become zero.

  This makes it possible to perform soft switching at zero voltage and zero current at the time of turning on the main switch without using a reactor as in the conventional chopper circuit, thereby eliminating the heat loss and improving the conversion efficiency of the chopper part, It also prevents overcurrent overvoltage.

  In addition, the auxiliary switch regenerates the charge accumulated in the output diode to the DC power supply, thereby preventing overvoltage due to reverse recovery of the output diode.

  Further, the bidirectional buck-boost chopper circuit of the present invention includes three main reactors that equivalently constitute one reactor, and each chopper section has the three main reactors as a shared reactor. Each chopper unit connects one end of each auxiliary switch to this shared reactor. Four chopper parts are connected by this shared reactor, and bidirectional chopper operation by each chopper part is enabled.

  The four chopper units included in the bidirectional buck-boost chopper circuit of the present invention include a first boost chopper unit that performs a boost operation from the first terminal to the second terminal, and a step-down from the first terminal to the second terminal. A first step-down chopper unit that operates, a second step-up chopper unit that performs a step-up operation from the second terminal to the first terminal, and a second step that performs the step-down operation from the second terminal to the first terminal. It is a step-down chopper unit, and by switching each chopper circuit to operate, four operations of bidirectional step-up / step-down operation can be performed with one circuit.

  In the bidirectional buck-boost chopper circuit according to the present invention, the second step-up chopper unit connected to the first terminal and the first step-down chopper unit connected to the first terminal constitute a main reactor when the auxiliary switch is turned on. A regenerative current is caused to flow in the opposite direction to the main current with respect to one same main reactor among the three main reactors.

  In addition, the first step-up chopper unit connected to the second terminal and the second step-down chopper unit connected to the second terminal include the above-described three main reactors that constitute the main reactor when the auxiliary switch is turned on. A regenerative current is caused to flow in the direction opposite to the main current with respect to one same main reactor different from the main reactor.

  When the present invention is applied to a step-up chopper circuit, a more detailed form is as follows: a series connection body of three main reactors equivalently constituting one reactor, one end of which is connected to a high potential side terminal of a DC power supply; , One pole connected to the other end of the series connection of the main reactor, the other pole connected directly to the low voltage terminal of the DC power supply, and the output diode and output connected between both poles of the main switch Connection of series connection body of smoothing capacitor, series connection body of snubber diode and snubber capacitor, connection point of snubber diode and snubber capacitor, and connection body of two main reactors connected between both poles of main switch And an auxiliary switch connected between the points.

  The auxiliary switch of the present invention allows the electric charge accumulated in the output diode to flow in the direction opposite to the main current of the main reactor to the main reactor on the DC power source side among the three main reactors when turning on. Regenerate to power. Thus, in addition to preventing overvoltage due to reverse recovery of the output diode, heat loss generated in the main reactor can be reduced by making the direction of flowing through the main reactor opposite to the main current of the main reactor.

  The main switch of the present invention, when turned on, regenerates resonance between the snubber capacitor and the main reactor connected to the DC power supply side, and charges stored in the snubber capacitor are transferred to the main reactor on the DC power supply side among the three main reactors. Then, it flows in the direction opposite to the main current of the main reactor and regenerates to the DC power supply. Heat loss generated in the main reactor can be reduced by setting the regenerative current passed through the main reactor in the opposite direction to the main current of the main reactor.

  When the main switch is turned on, in order to perform soft switching with zero current and zero voltage, the main switch is turned on after the auxiliary switch is turned on. As a result, the main switch can be turned on from a zero voltage and zero current state.

  The auxiliary switch can be configured by a reverse blocking IGBT, a series connection of an IGBT with an antiparallel diode and a diode, or a series connection of an IGBT and a diode that does not have a reverse blocking capability.

  As described above, according to the bidirectional buck-boost chopper circuit of the present invention, it is possible to reduce the loss of the bidirectional buck-boost chopper circuit and suppress overvoltage and overcurrent.

  According to the bidirectional buck-boost chopper circuit of the present invention, by turning on the auxiliary switch, the voltage of the snubber capacitor is set to zero voltage, the voltage when the main switch is turned on is set to zero voltage, and when this zero voltage is reached. By turning on the auxiliary switch, a regenerative resonance between the snubber capacitor and the main reactor is generated via the auxiliary switch, and a current caused by this regenerative resonance is passed in a direction to cancel the main current of the main switch. Can be turned on with zero voltage and zero current.

  As a result, soft switching is performed at zero voltage and zero current when the main switch is turned on without using a reactor as in the conventional chopper circuit, thereby eliminating the heat loss and improving the conversion efficiency of the chopper circuit. In addition, overcurrent overvoltage can be prevented. Thereby, the heat loss which generate | occur | produces in a reactor by soft switching operation | movement can be reduced, and conversion efficiency can be improved.

  Further, according to the bidirectional buck-boost chopper circuit of the present invention, it is possible to prevent an overcurrent overvoltage when the main switch is turned on, and to regenerate the electric charge accumulated in the output diode by the auxiliary switch to the DC power supply. Overvoltage due to reverse recovery of the diode can be prevented.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  Hereinafter, a configuration example of the bidirectional buck-boost chopper circuit of the present invention will be described with reference to FIG.

  In FIG. 1, the bidirectional step-up / step-down chopper circuit performs a step-up operation and a step-down operation between the power source side and the load side in both directions from the power source side to the load side and from the load side to the power source side. The power conversion is performed for a total of four operation modes.

In Figure 1, the power source side is constituted by a parallel connection of the input capacitor C _in the DC power supply E, the load side is constituted by parallel connection of the load RL and the output capacitor C _out.

  The bidirectional step-up / step-down chopper circuit realizes four operation modes, bidirectional and step-up and step-down, by two step-up chopper units and two step-down chopper units.

  Hereinafter, in FIG. 1, the direction from the power supply side to the load side is assumed to be the forward direction, and the direction from the load side to the power supply side is assumed to be the reverse direction.

Each chopper unit is equivalent to three main reactors (L _{1 to} L ₃ ) that constitute one reactor, and one pole is connected to one end (reactor L ₁ or reactor L ₃ ) of the series connection body of the main reactors. The main switches S _{1 to} S ₄ that directly connect the other pole to one voltage terminal of the DC power source E, and the snubber diodes D _{1 to} D ₄ and the snubber that are connected between both poles of the main switches S _{1 to} S ₄ Connection of capacitors C _{1 to} C ₄ in series, snubber diodes D _{1 to} D ₄ and snubber capacitors C _{1 to} C _4, and connection of two main reactors (L _{1 to} L ₃ ) Auxiliary switches S _{1a to} S _4a connected between the points (between reactor L ₁ and reactor L ₂ or between reactor L ₃ and reactor L ₁ ) are provided.

The forward step-up chopper unit that performs the step-up operation in the forward direction from the power supply side to the load side has two main reactors L ₂ and L ₃ that equivalently constitute one reactor, and one pole is connected to the main reactor L ₂ , one end of the series connection of L ₃ (in this case, reactor L ₁ connected to the reactor L ₂₎ connected to a main switch S ₁ directly connected to the other pole to one terminal of the load side, the main switch a series connection of the snubber diode D ₁ and the snubber capacitor C ₁ to be connected between both electrodes of the S _1, and the connection point between the snubber diode D ₁ and the snubber capacitor C _1, between the two main reactor L ₂ and L ₃ The auxiliary switch S _1a is connected.

The forward step-down step-down chopper unit that performs step-down operation in the forward direction from the power supply side to the load side has two main reactors L ₁ and L ₂ that equivalently constitute one reactor, and one pole is connected to the main reactor L ₁ , one end of the series connection of L ₂ (in this case, reactor L ₃ is connected to the reactor L ₂₎ connected to a main switch S ₄ for connecting directly to the other pole to one of the voltage terminal of the DC power source E, a series connection of the snubber diode D ₄ and the snubber capacitor C ₄ to connect between the two electrodes of the main switch S _4, and the connection point between the snubber diode D ₄ and the snubber capacitor C _4, the two main reactor L ₁ and L ₂ And an auxiliary switch S _4a connected therebetween.

In addition, the reverse boost chopper that performs a boost operation in the reverse direction from the load side to the power supply side has two main reactors L ₁ and L ₂ that equivalently constitute one reactor, and one pole as the main reactor L. _1, L (in this case, reactor L ₂ reactor L ₃ is connected to) the _second end of the series connection connected to the main switch S ₃ that connect directly to the other pole to one of the voltage terminal of the DC power source E , snubber diode D ₃ and the series connection of the snubber capacitor C _3, snubber diode D ₃ and the connection point of the snubber capacitor C _3, the two main reactor L ₁ and L ₂ to be connected between both electrodes of the main switch S ₃ And an auxiliary switch _S3a connected between the two.

The reverse step-down chopper unit that performs step-down operation in the reverse direction from the load side to the power source side is equivalent to two main reactors L ₁ and L ₂ that constitute one reactor, and one pole is connected to the main reactor L ₁ , (in this case, reactor L ₂ which is connected to the reactor L ₃₎ at one end of the series connection of L ₂ connected to the main switch S ₂ that connect directly to the other pole to one terminal of the load side, the main switch S connecting a series connection of the snubber diode D ₂ and the snubber capacitor C ₂ to be connected between _two of the poles, the connection point of the snubber diode D ₂ and the snubber capacitor C _2, between the two main reactor L ₃ and L ₂ And the auxiliary switch S _2a .

The bidirectional buck-boost chopper circuit includes three main reactors L ₁ , L ₂ , and L ₃ that equivalently constitute one reactor. The forward step-up chopper unit, the forward step-down chopper unit, the reverse step-up chopper unit, and the reverse step-down chopper unit constitute the circuit of the chopper circuit among the _three main reactors L ₁ , L ₂ , and L _3. in order to, with the construction to share the main reactor L _2, constitute one of the bidirectional buck-boost chopper circuit.

  Each chopper unit constitutes a snubber-assisted ZVZCT (Snubber-Assisted Zero Voltage and Zero Current Transition chopper) chopper circuit.

Here, FIG. 2 is a diagram showing a circuit configuration of a chopper section constituting the bidirectional buck-boost chopper circuit of the present invention, and FIG. 2A is a circuit for performing a boosting operation in each of the chopper sections described above. The configuration is cut out and shown in FIG. 2B, and the circuit configuration for performing the step-down operation in each of the chopper units described above is cut out and shown. The chopper circuit configurations of FIGS. 2A and 2B are the main switch S ₁ , auxiliary switch S ₂ , main reactors L ₁ and L ₂ , snubber diode D ₁ and snubber capacitor C ₂ , and output diode D. ₅ and an output smoothing capacitor C _3.

In the step-up chopper circuit configuration shown in FIG. 2A, the main reactors L ₁ and L ₂ are two reactors connected in series, but equivalently constitute one reactor and one end is connected to the DC power source E _1. Is connected to the high potential side terminal. The main switch S ₁ has one pole connected to the other end of the series connection body of the main reactors L ₁ and L ₂ and the other pole directly connected to the low voltage terminal of the DC power supply E ₁ . Between both poles of the main switch S ₁ , a series connection body of an output diode D ₅ and an output smoothing capacitor C ₃ is connected in parallel, and a load is connected in parallel to the output smoothing capacitor C ₃ . Further, a series connection body of a snubber diode D ₁ and a snubber capacitor C ₂ is connected between both poles of the main switch S ₁ . The auxiliary switch S ₂ is connected between the connection point of the snubber diode D ₁ and the snubber capacitor C ₂ and the connection point of the series connection body of the _two main reactors L ₁ and L ₂ .

Next, in the step-down chopper circuit configuration shown in FIG. 2 (b), the main reactors L ₁ and L ₂ are two reactors connected in series, but equivalently constitute one reactor and one end is loaded. It is connected to R _L and the smoothing capacitor C ₃ side terminal. The main switch S ₁ has one pole connected to the other end of the series connection body of the main reactors L ₁ and L ₂ and the other pole directly connected to the high voltage terminal of the DC power supply E ₁ . To one pole of the main switch S ₁ is output diode D ₅ is connected, at one end of the main reactor L ₂ load output smoothing capacitor C ₃ is connected in parallel. Further, a series connection body of a snubber diode D ₁ and a snubber capacitor C ₂ is connected between both poles of the main switch S ₁ . The auxiliary switch S ₂ is connected between the connection point of the snubber diode D ₁ and the snubber capacitor C ₂ and the connection point of the series connection body of the _two main reactors L ₁ and L ₂ .

In the configuration of this chopper circuit, the above-described QRAS chopper circuit is different from the above-described QRAS chopper circuit in that the regenerative diode connected to the reactor and the diode for providing a common snubber protection function for the main switching and the auxiliary switch are eliminated. ₂ is a reverse-blocking IGBT, the point where the current delay reactor connected to the main switch is deleted, and not only zero current but also switching at zero current and zero voltage when the main switch is turned on Is different.

The auxiliary switch S ₂ as by using a reverse blocking type IGBT, it is possible to remove the conventionally required regenerative diode.

In addition, since the auxiliary switch S ₂ having the chopper circuit configuration has zero-current switching as the turn-off operation, the diode for providing a common snubber protection function for the main switching S ₁ and the auxiliary switch S ₂ can be eliminated.

  The chopper circuit configuration included in the bidirectional buck-boost chopper circuit of the present invention is extinguished by passing the stored charge of the output diode through a part of the main reactor via the auxiliary switch, thereby suppressing the reverse recovery current. Can do.

2A and 2B, when the auxiliary switch S ₂ is turned on, the current I _R caused by the charge accumulated in the output diode D ₅ (indicated by the broken line in FIGS. 2A and 2B) flows in a direction opposite to the direction of the main current of the main reactor and main reactor L _2. This current I _R decreases the energization current of main reactor L ₂ . Therefore, active power component? Pr = I _R ² · R ₂ which occurs in the main reactor L ₂ acts as reducing the loss due to the resistance component R ₂ in the main reactor L _2. Note that by turning on the auxiliary switch S ₂ before turning on the main switch S _1, regenerates the charge accumulated in the output diode D ₅ to the input side.

Therefore, according to the chopper circuit configuration, the current I _R at the time of storing charge of the output diode D ₅ disappears becomes a direction to reduce the loss of the main reactor, which acts in a direction to increase the efficiency of the chopper circuit.

In the conventional QRAS chopper circuit, since the reactor L ₂ is large, the accumulated charge in the output diode D ₅ cannot be eliminated, and a large reverse recovery surge voltage due to the accumulated charge is generated when the output diode is turned off. On the other hand, in the chopper circuit configuration provided in the bidirectional buck-boost chopper circuit of the present invention, the stored charge annihilation current that acts in the direction of increasing the efficiency flows, so that a reverse recovery current suppression circuit is used, and a large reverse recovery surge voltage by the output diode Does not occur.

  In addition, the chopper circuit configuration provided in the bidirectional buck-boost chopper circuit of the present invention can reduce the switching loss by using the regenerative resonance phenomenon to create a zero voltage zero current state and turning it on.

In conventional QRAS chopper circuit, such that the current rises slowly during turn of the main switch S _1, which connects the reactor between the integral of the main switch S ₁ and a power supply. In contrast, the chopper circuit arrangement comprising a bidirectional buck-boost chopper circuit of the present invention, by forming a regenerative path by auxiliary switch S _2, are not necessary to the reactor. This regenerative path utilizes the regenerative resonance phenomenon of the snubber capacitor C ₂ , thereby creating a state of zero voltage and zero current in the main switch S ₁ .

  As a result, the clamp voltage of the snubber capacitor, which greatly exceeds the power supply voltage generated at the time of turn-on, can be suppressed to a low voltage up to the power supply voltage. Therefore, the capacity of the snubber capacitor can be selected to be small according to the turn-on time of the main switch, the snubber regenerative power itself can be reduced, and the efficiency of the entire chopper circuit can be improved.

In the chopper circuit configuration provided in the bidirectional buck-boost chopper circuit of the present invention, the snubber capacitor C ₂ is provided for soft-switching the main switch S ₁ , and the energy stored in the snubber capacitor C ₂ is used. during turn of the main switch S _1, the auxiliary switch through the S ₂ and the input-side, and zero current flowing into the main switch S ₁ that flows to the antiparallel diode is connected to the main switch S _1, further snubber capacitor C ₂ with zero voltage across the main switch S ₁ by the discharge.

Further, the chopper circuit arrangement bidirectional buck chopper circuit of the present invention comprises, a regenerative current Is (FIG. 2 (a), the shown by the one-dot chain line in (b)) reduces the energization current of the main reactor L ₂ Since the power is regenerated in the direction, the active power component ΔPs = I _S ² · R ₂ generated during the regenerative action acts to reduce the loss of the main reactor L ₂ and to increase the efficiency of the chopper circuit. R ₂ is the internal resistance of the main reactor L ₂ .

  As described above, the chopper circuit configuration included in the bidirectional buck-boost chopper circuit of the present invention functions as a reverse recovery current suppression circuit that extinguishes the accumulated charge of the output diode, and does not require a regenerative reactor by using regenerative resonance. Acts as soft switching.

  In addition, the bidirectional chopper circuit of the present invention has a chopper circuit configuration in which the main reactor is divided so that the regenerative reactor is not required and the energy stored in the output diode and snubber capacitor is directly used. Power loss in the main reactor can be reduced by flowing in a direction that cancels the main current of the main reactor instead of regenerating to the power source side.

The chopper circuit of the present invention can transfer the energy of the snubber capacitor directly to the main reactor without using an auxiliary regenerative capacitor. For example, even if the charging voltage of the snubber capacitor is charged higher than the output voltage due to the influence of the wiring reactor, the regenerative energy is transferred to the main reactor L ₂ in the input power direction, and the regenerative energy in the output direction is The main reactor L ₁ can be made to regenerate each. Therefore, it is possible to achieve higher efficiency than a method of using a reactor separately from the main reactor and regenerating via an auxiliary circuit path other than the main circuit.

  Next, an operation example of the chopper circuit configuration provided in the bidirectional buck-boost chopper circuit of the present invention will be described with reference to FIGS. 3 is an operation diagram of the step-up chopper circuit configuration, FIG. 4 is an operation diagram of the step-down chopper circuit configuration, and FIG. 5 is a basic operation waveform diagram of each part.

In the step-up chopper circuit configuration shown in FIG. 3, in mode 1 (Mode 1 in FIG. 3A), the auxiliary switch S ₂ is turned on at the time of -t ₂ and the output diode D is in the state where the main switch S ₁ is turned off. ₅ carrier disappearance mode begins. This moment, the auxiliary switch S ₂ is turned on from the current zero, it turns on the soft switching. During this time, the voltage of the snubber capacitor C ₂ maintains a substantially constant voltage not discharged. This mode ends when the current of the auxiliary switch S ₂ increases and the carrier of the output diode D ₅ disappears from the point when the load current is almost reached, reversely recovers and is turned off.

In FIG. 3A, the solid line indicates the main current flowing from the power supply side to the load side, and the broken line indicates the current flowing in the reverse direction by the carriers accumulated in the output diode D ₅ when the auxiliary switch S _2a is turned on. It is.

In mode 2 (Mode 2 in FIG. 3B), at the time of -t ₁ , the output diode D ₅ is turned off, and the voltage V _C2 of the snubber capacitor C ₂ resonates in a sinusoidal manner and goes from positive to zero. The broken line in FIG.3 (b) has shown this electric current. Also, the solid line in FIG. 3 (b) indicates the current that flows through the main reactor L _{1 circulates} through the auxiliary switch S _2a when the output diode D ₅ is turned off.

In mode 3 (Mode 3 in FIG. 3C), all charges accumulated in the snubber capacitor C ₂ are discharged, and at time t ₀ when the voltage V _C2 becomes zero voltage, the main switch S ₁ is turned on and resonance occurs. regenerative current (the broken line in FIG. 3 (c)) is Tsuryu in a direction to cancel the main current of the main switch S _1. At this time, the main switch S ₁ is turned on from zero current. The regenerative energy stored in the main reactor L ₂ during the mode 1 and mode 2 is regenerated to the input power source via the auxiliary switch S ₂ while canceling out the current of the main switch S ₁ as a negative current source. , Almost linearly decreasing to zero.

In mode 4 (Mode 4 in FIG. 3D), at t ₁ , the regenerative current of the main reactor L ₂ decreases to zero, the diode D ₁ is turned off, and the currents of the main reactors L ₁ and L ₂ are toward increased again linearly through a switch S _1.

In mode 5 (Mode 5 in FIG. 3E), at time t ₂ , the main switch S ₁ and the auxiliary switch S ₂ are simultaneously turned off. At this time, the main switch S ₁ is turned off from zero voltage by the snubber capacitor C ₂ , and the auxiliary switch S ₂ is turned off by zero current, and both are turned off by soft switching. However, the present invention is not limited to simultaneous off. The auxiliary switch S ₂ may be turned off prior to the main switch S ₁ when zero current is reached.

In mode 6 (Mode 6 in FIG. 3 (f)), at t ₃ , the output diode D ₅ is turned on, and the energy stored in the main reactors L ₁ and L ₂ is supplied to the load. At t ₄ , the auxiliary switch S ₂ is turned on again, and the next cycle is started from mode 1.

As described above, operate in soft switching in the main switch auxiliary switch both overcurrent by reverse recovery current of the output diode D _5, the overvoltage does not occur.

  In the bidirectional buck-boost chopper circuit according to the present invention, the circuit configuration of the step-up chopper circuit configuration and the step-down chopper circuit configuration are symmetrical, and therefore both the chopper circuit configurations operate in substantially the same manner.

In the step-down chopper circuit configuration shown in FIG. 4, in mode 1 (Mode 1 in FIG. 4A), the auxiliary switch S ₂ is turned on at the time of -t ₂ and the output diode D is in the state where the main switch S ₁ is turned off. The carrier annihilation mode of ₅ starts (current indicated by a broken line in FIG. 4A). This moment, the auxiliary switch S ₂ is turned on from the current zero, it turns on the soft switching. During this time, the voltage of the snubber capacitor C ₂ maintains a substantially constant voltage not discharged. This mode ends when the current of the auxiliary switch S ₂ increases and the carrier of the output diode D ₅ disappears from the point when the load current is almost reached, reversely recovers and is turned off.

In FIG. 4A, the solid line indicates the main current flowing to the load side, and the broken line is the current flowing in the reverse direction by the carriers accumulated in the output diode D ₅ when the auxiliary switch S ₂ is turned on.

In mode 2 (Mode 2 in FIG. 4B), at the time of -t ₁ , the output diode D ₅ is turned off, and the voltage V _C2 of the snubber capacitor C ₂ resonates in a sinusoidal manner and goes from positive to zero. The broken line in FIG.4 (b) has shown this electric current. Also, the solid line in FIG. 4B indicates the current that flows through the main reactor L ₁ and circulates through the auxiliary switch S ₂ when the output diode D ₅ is turned off.

In mode 3 (Mode 3 in FIG. 4C), all charges accumulated in the snubber capacitor C ₂ are discharged, and at time t ₀ when the voltage V _C2 becomes zero voltage, the main switch S ₁ is turned on and resonance occurs. regenerative current (the broken line in FIG. 4 (c)) is Tsuryu in a direction to cancel the main current of the main switch S _1. At this time, the main switch S ₁ is turned on from zero current. The regenerative energy stored in the main reactor L ₂ during the mode 1 period is regenerated to the input power source via the auxiliary switch S ₂ while canceling the current of the main switch S ₁ as a negative current source, and is almost linear. Decreases to zero.

In mode 4 (Mode 4 in FIG. 4D), at t ₁ , the regenerative current of main reactor L ₂ decreases to zero, diode D ₁ is turned off, and the currents of main reactors L ₁ and L ₂ are the main currents. toward increased again linearly through a switch S _1.

In mode 5 (Mode 5 in FIG. 4E), at time t ₂ , the main switch S ₁ and the auxiliary switch S ₂ are simultaneously turned off. At this time, the main switch S ₁ is turned off from zero voltage by the snubber capacitor C ₂ , and the auxiliary switch S ₂ is turned off by zero current, and both are turned off by soft switching. However, the present invention is not limited to simultaneous off. The auxiliary switch S ₂ may be turned off prior to the main switch S ₁ when zero current is reached.

In mode 6 (Mode 6 in FIG. 4 (f)), at t ₃ , the output diode D ₅ is turned on, and the energy stored in the main reactors L ₁ and L ₂ is supplied to the load. At t ₄ , the auxiliary switch S ₂ is turned on again, and the next cycle is started from mode 1.

As described above, operate in soft switching in the main switch auxiliary switch both overcurrent by reverse recovery current of the output diode D _5, the overvoltage does not occur.

As described above, the recovery operation (recovery operation) of the output diode D ₅ when the auxiliary switch S _{2 of} Mode 1 is turned on, the discharge operation of the snubber capacitor C ₂ of Mode 2 (ZVT operation (transition of the stored energy to zero potential and reactor) Zero Voltage Transition), ZCS (Zero Current Switching Zero Current) operation in which a reverse current flows through the anti-parallel diode of the main switch S _{1 in} Mode _{3 and} the forward current of the main switch S ₁ is zero is when the main switch S ₁ is turned on. The partial resonance operation is configured.

Incidentally, ZCS (Zero Current Switching zero current) operation, when turning on the auxiliary switch S _1a, caused by the current change is suppressed by the reactor in the Mode1, also at the time of turn-off of the auxiliary switch S _1a, in Mode4, energy regeneration After the operation is completed, it is caused by the operation from the state where the zero current is maintained in the reverse blocking state by the diode.

Next, the operation of the bidirectional buck-boost chopper circuit of the present invention will be described with reference to FIGS. 6 is an operation diagram of the forward step-up operation, FIG. 8 is an operation diagram of the forward step-down operation, FIG. 9 is an operation diagram of the reverse step-up operation, and FIG. 10 is an operation of the reverse step-down operation. FIG. 7 is a waveform diagram in each operation. Hereinafter, for each operation, six operation states of Mode1 to Mode6 will be shown, and the numbers 1 to 6 shown in FIG. 8 correspond to the six operation states of Mode1 to Mode6. Further, in FIG 6,8～10 mainly in order to perform the operations described in KakuNoboru step-down chopper unit, and simplify the operation of the power supply side and load side, power supply side of the input capacitor C _in the load side of the output capacitor The operation state will be described based on the current state between _Cout .

First, the forward boost operation will be described with reference to FIGS. The forward boost operation is performed by a forward boost chopper unit including a main switch S ₁ , an auxiliary switch S _{1a and the} like in the bidirectional buck-boost chopper circuit shown in FIG.

On the forward step-up operation, the conductive state is applied constantly to the on-gate to the main switch S _4, the main switch S _2, S _3, and stopped state auxiliary switch S _2a, the S _3a as normally-off. Moreover, operating the anti-parallel diode of the main switch S ₂ as the output diode.

In the bidirectional buck-boost chopper circuit shown in FIG. 6, in the mode 1 (Mode1 in FIG. 6 (a)), the main switch S ₁ and the auxiliary switch S _1a is in the OFF state, by the auxiliary switch S _1a is turned on, A path of the auxiliary switch S _1a , the main reactor L ₃ , the main switch S ₄ , the input capacitor C _in , the output capacitor C _out , the antiparallel diode of the main switch S ₂ , and the snubber capacitor C ₁ is formed. The solid line in FIG. 6A indicates this route.

Carriers accumulated in the anti-parallel diode of the main switch S ₂ (here corresponding to the output diode) flows in the opposite direction to the forward direction of the diode, the carrier extinction is started. Moment the auxiliary switch S _1a is turned on, the auxiliary switch S _1a is turned on from the current zero, it will be turned on at soft switching. While the auxiliary switch S _1a is turned on, the voltage of the snubber capacitor C ₁ is not discharged and maintains a substantially constant voltage.

From the point in time when the current of the auxiliary switch S _1a increases and almost reaches the load current, the accumulated carriers of the anti-parallel diode of the main switch S ₂ flow through the path and disappear, reversely recover and enter the off state. This mode 1 is completed by the recovery and extinction operation of the diode.

Further, the state indicated by “1” in FIG. 7 indicates a state in which the current flowing through the main switch S ₁ is zero, the voltage of the auxiliary switch 1a is decreased, and the current increases, and the current flowing through the output diode is decreased. It shows the state to do.

In mode 2 (Mode 2 in FIG. 6B), the anti-parallel diode (corresponding to the output diode) of the main switch S ₂ is turned off, and the voltage VC ₁ of the snubber capacitor C ₁ resonates in a sine wave shape and changes from positive to zero. Head to. The solid line in FIG. 6B shows the current flowing through the path of the snubber capacitor C ₁ , the auxiliary switch S _1a , the main reactor L ₃ , the main switch S ₄ , and the input capacitor Cin. This mode is a ZVT operation in which the voltage of the snubber capacitor C ₁ is changed to zero voltage.

The state indicated by “2” in FIG. 7 indicates a state in which the current flowing through the main switch S ₁ increases and the current through the auxiliary switch 1a increases, and the current flowing through the output diode indicates a zero state. Yes.

In mode 3 (Mode 3 in FIG. 6C), all charges accumulated in the snubber capacitor C ₂ are discharged, and when the voltage V _C2 becomes zero, the main switch S ₁ is turned on and the resonance regenerative current is turned on. Flows in a direction to cancel the main current of the main switch S ₁ .

The solid line in FIG. 6C shows the path of the main switch S ₁ , snubber diode D ₁ , main reactor L ₃ , main switch S ₄ , and input capacitor C _{in in} this mode. In this mode, the main switch S ₁ is turned on from zero current due to cancellation by the circulating current from the snubber capacitor C ₁ . The regenerative energy stored in the main reactor L ₃ during the mode 1 and mode 2 is regenerated to the input power source via the auxiliary switch S _1a while canceling the current of the main switch S ₁ as a negative current source. , Almost linearly decreasing to zero. This operation is a ZCS (Zero Current Switching zero current) operation in which the forward current of the main switch S ₁ is zero.

Further, a state indicated by “3” in FIG. 7 indicates a state in which the voltage of the main switch S ₁ is zero and the current of the auxiliary switch 1a decreases, and the current flowing through the output diode indicates a zero state.

In mode 4 (Mode4 in FIG. 6 (d)), becomes zero regenerative current of the main reactor L ₃ is reduced, snubber diode D ₁ is turned off, the current of the main reactor L ₃ is connected via a main switch S ₁ Again, it increases linearly. The solid line _in FIG. 6D shows the path of the main switch S ₁ , the main reactor L ₃ , the main switch S ₄ , and the input capacitor C _{in in} this mode. Further, the state indicated by “4” in FIG. 7 indicates the voltage and current state at this time.

In mode 5 (Mode 5 in FIG. 3E), the main switch S ₁ and the auxiliary switch S _1a are simultaneously turned off. At this time, the main switch S ₁ is turned off from zero voltage by the snubber capacitor C ₁ , and the auxiliary switch S _1a is turned off by zero current, and both are turned off by soft switching. The solid line in FIG. 6E shows the path of the input capacitor C _in , the main switch S ₄ , the main reactors L _{3 to} L ₁ , the snubber diode D ₁ , and the snubber capacitor C ₁ in this mode. Further, the state indicated by “5” in FIG. 7 indicates the voltage and current state at this time.

However, the present invention is not limited to simultaneous off. The auxiliary switch S _1a may be turned off prior to the main switch S ₁ when zero current is reached.

In mode 6 (Mode 6 of FIG. 6 (f)), the voltage rise due to increased current in the main reactor, the anti-parallel diode of the main switch S ₂ is turned on, the main reactor L ₁ ~L ₃ the energy stored in the load (Output capacitor C _out ). The solid line in FIG. 6 (f) indicates the path of the input capacitor C _in , the main switch S ₄ , the main reactors L _{3 to} L ₁ , the antiparallel diode of the main switch S ₂ , and the output capacitor C _out in this mode. . Further, the state indicated by “6” in FIG. 7 indicates the voltage and current state at this time.

After this mode 6, when the auxiliary switch S _1a is turned on again, the mode is returned to the mode 1 and the next cycle is started.

As described above, it operates in the main switch auxiliary switch both the soft switching, output diode (here, the main anti-parallel diode of the switch S ₂₎ over-current, over-voltage is not generated by the reverse recovery current.

Next, the forward step-down operation will be described with reference to FIG. The forward voltage step-down operation is performed by a forward voltage step-down chopper unit including a main switch S ₄ , an auxiliary switch S _{4a and the} like in the bidirectional step-up / step-down chopper circuit shown in FIG.

On the forward step-down operation, the conductive state is applied constantly to the on-gate to the main switch S _2, a main switch S _1, S _3, and stopped state auxiliary switch S _1a, the S _3a as normally-off. Moreover, operating the anti-parallel diode of the main switch S ₃ as wheeling diode.

In the step-down chopper unit shown in FIG. 8, in mode 1 (Mode 1 in FIG. 8A), the auxiliary switch S _4a is turned on and the main switch S ₂ and the main reactor are turned on when the main switches S ₁ and S ₃ are turned off. A path of L ₁ , auxiliary switch S _4a , snubber capacitor D ₄ , anti-parallel diode (operating as a freewheeling diode) of main switch S ₃ , and output capacitor C _out is formed. The solid line in FIG. 6A indicates this route. In this mode, the carrier disappears by wheeling diode (anti-parallel diode of the main switch S ₃₎ is performed.

The auxiliary switch _S4a is turned on from zero current and is turned on by soft switching. During this time, the voltage of the snubber capacitor C ₄ is not discharged and is maintained at a substantially constant voltage. When the current of the auxiliary switch S _4a increases and almost reaches the load current, the carrier of the output diode (the anti-parallel diode of the main switch S ₂ ) disappears, reversely recovers and turns off, and mode 1 ends. To do.

In mode 2 (Mode 2 in FIG. 8B), the output diode (the antiparallel diode of the main switch S ₂ ) is turned off, and the voltage V _C4 of the snubber capacitor C ₄ resonates in a sinusoidal manner and goes from positive to zero. . The solid line in FIG. 8 (b) in the current flowing through the main reactor L ₁ is, output diode (anti-parallel diode of the main switch S ₂₎ indicates the current circulating through the auxiliary switch S _4a by turning off.

This mode is a ZVT operation in which the voltage of the snubber capacitor C ₄ is changed to zero voltage.

In mode 3 (Mode 3 in FIG. 8C), all charges accumulated in the snubber capacitor C ₄ are discharged, and when the voltage V _C4 becomes zero, the main switch S ₄ is turned on and the main reactor L resonance regenerative current from ₁ Tsuryu in a direction to cancel the main current of the main switch S _4. As a result, the main switch S ₄ is turned on from zero current. The regenerative energy stored in the main reactor L ₂ during the mode 1 period is regenerated to the input power source through the auxiliary switch S _4a while canceling the current of the main switch S ₄ as a negative current source, and is almost linear. Decreases to zero.

This operation is ZCS (Zero Current Switching zero current) operation with zero forward current of the main switch S _4.

Mode 4 In (Mode4 in FIG 8 (d)), the main switch S ₄ is in the ON state, becomes zero regenerative current of the main reactor L ₁ is decreased, the output diode (anti-parallel diode of the main switch S ₂₎ is turned off Then, the current of the main reactor L ₁ again increases linearly via the main switch S ₄ .

In mode 5 (Mode 5 in FIG. 4E), the main switch S ₄ and the auxiliary switch S _4a are simultaneously turned off. At this time, the main switch S ₄ is turned off from zero voltage by the snubber capacitor C ₄ , and the auxiliary switch S _4a is turned off by zero current, and both are turned off by soft switching.

  A solid line in FIG. 8E indicates a route in this mode.

However, the present invention is not limited to simultaneous off. The auxiliary switch S ₂ may be turned off prior to the main switch S ₁ when zero current is reached.

In mode 6 (Mode 6 in FIG. 8F), the main switch S ₄ and the auxiliary switch S _4a are in the off state, the output diode (the antiparallel diode of the main switch S ₂ ) is turned on, and the main reactors L ₁ , L _The energy stored in ₂ is supplied to the load. The solid line in FIG. 8F shows the paths of the main switch S ₃ , the main reactors L _{3 to} L ₁ , the antiparallel diode of the main switch S ₂ , and the output capacitor C _out in this mode.

Thereafter, the auxiliary switch S _4a is turned on again, and the next cycle is started from the mode 1 described above. The voltage and current states are the same as those in FIG.

  As described above, both the main switch and the auxiliary switch operate by soft switching, and overcurrent and overvoltage due to the reverse recovery current of the output diode do not occur.

Next, the reverse boost operation will be described with reference to FIG. The reverse boost operation is performed by the reverse boost chopper unit including the main switch S ₃ and the auxiliary switch S _3a in the bidirectional step-up / down chopper circuit shown in FIG.

On the reverse boost operation, the conductive state is applied constantly to the on-gate to the main switch S _2, a main switch S _1, S _4, and stopped state auxiliary switch S _1a, the S _4a as normally-off. Moreover, operating the anti-parallel diode of the main switch S ₄ as the output diode.

In the bidirectional step-up / step-down chopper circuit shown in FIG. 9, when the main switch S ₃ and the auxiliary switch S _3a are in the OFF state, the main switch S ₂ is always in a conductive state, so that the main reactors L _{3 to} L are output from the output capacitor C _{out. 1 is in} a state of flowing through the path of the main switch S ₄ and the input capacitor C _in (mode 6 state). In this state, when the auxiliary switch S _3a is turned on in mode 1 (Mode 1 in FIG. 9A), the auxiliary switch S _3a , the main reactor L ₁ , the main switch S ₂ , the output capacitor C _out , and the input capacitor C _in , a path of the anti-parallel diode of the main switch S ₄ and the snubber diode D ₃ is formed. A solid line in FIG. 9A indicates this route.

Carriers accumulated in the anti-parallel diode of the main switch S ₄ (here corresponding to the output diode) flows in the opposite direction to the forward direction of the diode, the carrier extinction is started. Moment the auxiliary switch S _3a is turned on, the auxiliary switch S _3a is turned on from the current zero, it will be turned on at soft switching. While the auxiliary switch S _3a is turned on, the voltage of the snubber capacitor C ₃ is not discharged and maintains a substantially constant voltage.

Auxiliary current switch _3a is increased, the accumulation carrier substantially anti-parallel diode of the main switch S ₄ from the time it reaches the load current, and disappears flows the path, it turned off and reverse recovery. This mode 1 is completed by the recovery and extinction operation of the diode.

In mode 2 (Mode 2 in FIG. 9B), the anti-parallel diode (corresponding to the output diode) of the main switch S ₄ is turned off, and the voltage V _C1 of the snubber capacitor C ₃ resonates in a sinusoidal manner and changes from positive to zero. Head to. The solid line in FIG. 9B shows the current flowing through the path of the snubber capacitor C ₃ , the auxiliary switch _{3 a} , the main reactor L ₁ , the main switch S ₂ , and the output capacitor C _out . This mode is ZVT operation to transition the voltage of the snubber capacitor C ₃ to zero voltage.

In mode 3 (Mode 3 in FIG. 6C), all charges accumulated in the snubber capacitor C ₃ are discharged, and when the voltage V _C3 becomes zero, the main switch S ₃ is turned on and the resonance regenerative current is turned on. is Tsuryu in a direction to cancel the main current of the main switch S _3.

The solid line in FIG. 9C shows the path of the main switch S ₃ , snubber diode D ₃ , main reactor L ₁ , main switch S ₂ , and output capacitor C _out in this mode. In this mode, the main switch S ₃ is turned on from zero current due to cancellation by the circulating current from the snubber capacitor C ₃ . The regenerative energy stored in the main reactor L ₁ during the period of mode 1 and mode 2 is regenerated to the input power source via the auxiliary switch S _3a while canceling the current of the main switch S ₃ as a negative current source. , Almost linearly decreasing to zero. This operation is ZCS (Zero Current Switching zero current) operation with zero forward current of the main switch S _3.

In mode 4 (Mode 4 in FIG. 9D), the regenerative current of the main reactor L ₁ decreases to zero, the snubber diode D ₃ is turned off, and the current of the main reactor L ₁ passes through the main switch S _3. Again, it increases linearly. The solid line in FIG. 9 (d) in this mode, the main switch S3, the main reactor L _1, the main switch S _2, shows the path of the output capacitor C _out.

In mode 5 (Mode 5 in FIG. 9E), the main switch S ₃ and the auxiliary switch S _3a are simultaneously turned off. At this time, the main switch S ₃ is turned off from zero voltage by the snubber capacitor C ₃ , and the auxiliary switch S _3a is turned off by zero current, and both are turned off by soft switching. The solid line in FIG. 9E shows the path of the output capacitor C _out , the main switch S ₂ , the main reactors L _{1 to} L ₃ , the snubber diode D ₃ , and the snubber capacitor C ₃ in this mode.

However, the present invention is not limited to simultaneous off. The auxiliary switch S _3a may be turned off prior to the main switch S ₃ when zero current is reached.

In mode 6 (Mode 6 of Fig. 9 (f)), the voltage rise due to increased current in the main reactor, the anti-parallel diode of the main switch S ₄ is turned on, the main reactor L ₁ ~L ₃ the energy stored in the input Regenerated to the side (input capacitor C _in ). The solid line in FIG. 9F shows the path of the output capacitor C _out , the main switch S ₂ , the main reactors L _{3 to} L ₁ , the antiparallel diode of the main switch S ₄ , and the input capacitor C _{in in} this mode. .

After the mode 6, the auxiliary switch _S3a is turned on again to return to the mode 1 and start the next cycle.

As described above, it operates in the main switch auxiliary switch both the soft switching, output diode (here, the main anti-parallel diode of the switch S ₂₎ over-current, over-voltage is not generated by the reverse recovery current.

Next, the reverse step-down operation will be described with reference to FIG. The reverse step-down operation is performed by a reverse step-down chopper unit including a main switch S ₂ , an auxiliary switch S _2a, etc. in the bidirectional step-up / step-down chopper circuit shown in FIG.

On the reverse step-down operation, the conductive state is applied constantly to the on-gate to the main switch S _4, the main switch S _1, S _3, and stopped state auxiliary switch S _1a, the S _3a as normally-off. Moreover, operating the anti-parallel diode of the main switch S ₁ as wheeling diode.

In the step-down chopper unit shown in FIG. 10, in mode 1 (Mode 1 in FIG. 10A), the auxiliary switch S _2a is turned on, the main switch S ₄ , and the main reactor in the state where the main switches S ₁ and S ₃ are turned off. A path of L ₃ , auxiliary switch S _2a , snubber capacitor D ₂ , anti-parallel diode of main switch S ₁ (operating as a freewheeling diode), and input capacitor C _in is formed. The solid line in FIG. 10A shows this route. In this mode, the carrier disappears by wheeling diode (anti-parallel diode of the main switch S ₁₎ is performed.

The auxiliary switch S _2a is turned on from zero current and is turned on by soft switching. During this time, the voltage of the snubber capacitor C ₂ maintains a substantially constant voltage not discharged. Mode 1 ends when the carrier of the output diode (the anti-parallel diode of the main switch S ₄ ) disappears from the point when the current of the auxiliary switch S _2a increases and almost reaches the load current, reversely recovers and turns off. To do.

In mode 2 (Mode 2 in FIG. 10B), the input diode (the antiparallel diode of the main switch S ₄ ) is turned off, and the voltage V _C2 of the snubber capacitor C ₂ resonates in a sine wave shape and goes from positive to zero. . The solid line in FIG. 10 (b) in the current flowing through the main reactor L ₃ is, output diode (anti-parallel diode of the main switch S ₄₎ indicates the current circulating through the auxiliary switch S _2a by turning off.

This mode is a ZVT operation in which the voltage of the snubber capacitor C ₂ is changed to zero voltage.

In mode 3 (Mode 3 in FIG. 10 (c)), all charges accumulated in the snubber capacitor C ₂ are discharged, and when the voltage V _C2 becomes zero, the main switch S ₂ is turned on and the main reactor L resonance regenerative current from ₃ Tsuryu in a direction to cancel the main current of the main switch S _2. Accordingly, the main switch S ₂ is the turn-on of the current zero. The regenerative energy stored in the main reactor L ₃ during the mode 1 period is regenerated to the input power source through the auxiliary switch S _2a while canceling the current of the main switch S ₂ as a negative current source, and is almost linear. Decreases to zero.

This operation is ZCS (Zero Current Switching zero current) operation with zero forward current of the main switch S _2.

Mode 4 In (Mode4 in FIG 10 (d)), the main switch S ₂ is turned on, becomes zero and the regenerative current of the main reactor L ₁ is decreased, the output diode (anti-parallel diode of the main switch S ₄₎ is turned off Then, the current of the main reactor L ₃ again increases linearly via the main switch S ₂ .

In mode 5 (Mode 5 in FIG. 10E), the main switch S ₂ and the auxiliary switch S _2a are simultaneously turned off. At this time, the main switch S ₂ is turned off from zero voltage by the snubber capacitor C _2, the auxiliary switches S _2a becomes zero current turn-off, turn off both soft switching.

  A solid line in FIG. 10E indicates a route in this mode.

However, the present invention is not limited to simultaneous off. The auxiliary switch S _2a may be turned off prior to the main switch S ₂ when zero current is reached.

In mode 6 (Mode 6 in FIG. 10 (f)), the main switch S ₂ and the auxiliary switch S _2a are in the off state, the output diode (the antiparallel diode of the main switch S ₄ ) is turned on, and is stored in the main reactor L ₃ . The supplied energy is supplied to the load. The solid line in FIG. 10 (f) is, in this mode shows the main switch S _1, the main reactor L ₁ ~L _3, the anti-parallel diode of the main switch S _4, the path of the input capacitor C _in.

Thereafter, the auxiliary switch S _2a is turned on again, and the next cycle is started from the mode 1 described above. The voltage and current states are the same as those in FIG.

  As described above, both the main switch and the auxiliary switch operate by soft switching, and overcurrent and overvoltage due to the reverse recovery current of the output diode do not occur.

  In each chopper part of the bidirectional buck-boost chopper circuit of the present invention, soft switching is performed by turning on the auxiliary switch slightly earlier than the main switch. However, the main switch and the auxiliary switch can be switched simultaneously or the auxiliary switch from the main switch. However, by turning it on later, it is possible to operate so as to perform only the regenerative operation without performing the soft switching of the turn-on.

  The chopper circuit of the present invention may be configured by multiplexing the entire power supply system in addition to the main switch and auxiliary switch connected in series and parallel.

  Further, the main reactor of the chopper circuit of the present invention may have a split structure or an integral structure.

  In the chopper circuit of the present invention, the antiparallel diode of the main switch may be deleted when soft switching of zero voltage and zero current is not performed.

  Further, in the chopper circuit of the present invention, the input smoothing capacitor may be deleted when the input power supply has a current ripple absorption capability.

  In the chopper circuit according to the present invention, when the voltage difference between the input voltage and the output voltage is small during the boosting operation (when the boosting rate is low and the main switch ON period is short), or the input voltage and the output voltage during the bucking operation. Is large (when the step-down rate is high and the ON period of the main switch is short), the voltage may remain in the snubber capacitor. In this case, the low current effect due to the diode recovery current extinction and the low voltage effect due to the residual voltage result in a turn-on from the low voltage / low current, thereby reducing the overlap of voltage / current and reducing the switching loss. The

  The present invention is not limited to the embodiments described above. Various modifications can be made based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

  The chopper circuit of the present invention can be applied not only to a fuel cell vehicle but also to a field using a semiconductor power converter.

It is a figure which shows the circuit structural example of the bidirectional | two-way buck-boost chopper circuit of this invention. It is a figure which shows the circuit structure of the chopper part which comprises the bidirectional | two-way buck-boost chopper circuit of this invention. It is a circuit diagram for demonstrating the operation example of the pressure | voltage rise chopper circuit structure with which the bidirectional | two-way buck-boost chopper circuit of this invention is provided. It is a circuit diagram for demonstrating the operation example of the pressure | voltage fall chopper circuit structure with which the bidirectional | two-way buck-boost chopper circuit of this invention is provided. It is a basic operation waveform diagram of the bidirectional buck-boost chopper circuit of the present invention. It is an operation | movement diagram for demonstrating the forward boosting operation | movement of the bidirectional | two-way buck-boost chopper circuit of this invention. It is an operation | movement waveform diagram for demonstrating operation | movement of the bidirectional | two-way buck-boost chopper circuit of this invention. It is an operation | movement diagram for demonstrating the forward step-down operation | movement of the bidirectional | two-way buck-boost chopper circuit of this invention. It is an operation | movement diagram for demonstrating the reverse pressure | voltage rise operation | movement of the bidirectional | two-way buck-boost chopper circuit of this invention. It is an operation | movement diagram for demonstrating the reverse raising / lowering operation | movement of the bidirectional | two-way buck-boost chopper circuit of this invention. It is a figure which shows the bidirectional | two-way buck-boost chopper circuit assumed with the conventional chopper circuit.

Explanation of symbols

E, E1 ... DC power source S ₁ to S ₄ ... main switch S _1a to S _4a ... auxiliary switch C ₁ -C ₄ ... snubber capacitor D ₁ to D ₄ ... snubber diode L ₁ ~L _3, L ₂ ... main reactor C _in … Input capacitor C _out … Output capacitor C ₀ … Smoothing output capacitor

Claims (10)

In a bidirectional buck-boost chopper circuit that performs a boost operation and a step-down operation bidirectionally between a power supply side terminal and a load side terminal ,
Between the power supply side terminal and the load side terminal, comprising four electrically equivalent chopper parts that perform a step-up operation or a step-down operation,
Each chopper part is
Three main reactors equivalently constituting one reactor,
A main switch in which one pole is connected to one end of the series connection body of the main reactor, and the other pole is directly connected to one voltage terminal of the DC power supply;
A series connection body of a snubber diode and a snubber capacitor connected between both poles of the main switch,
A bidirectional buck-boost chopper circuit comprising an auxiliary switch connected between a connection point of the snubber diode and a snubber capacitor and a connection point of a series connection body of the three main reactors.   Each of the chopper parts has the three main reactors as a shared reactor, and the auxiliary switches of the chopper circuits are symmetrically connected to both ends of an intermediate main reactor in the three main reactors. The bidirectional buck-boost chopper circuit according to claim 1.   3. The bidirectional buck-boost chopper circuit according to claim 2, wherein each chopper unit connects one end of each auxiliary switch to the shared reactor. The four chopper parts are
A first step-up chopper unit that performs a step-up operation from the power supply side terminal to the load side terminal ;
A first step-down chopper unit that performs step-down operation from the power supply side terminal to the load side terminal ;
A second step-up chopper unit that performs a step-up operation from the load side terminal to the power source side terminal ;
4. The bidirectional step-up / step-down chopper circuit according to claim 1, wherein the bidirectional step-up / step-down chopper circuit is a second step-down chopper unit that performs step-down operation from a load side terminal to a power source side terminal . First step-down chopper unit connected to the second step-up chopper unit connected to the power supply side terminal to the power source side terminal, one and the same main in three main reactor constituting the main reactor during on of the auxiliary switch A regenerative current is applied to the reactor in the direction opposite to the main current,
Second step-down chopper unit connected to the first said load side terminal and the boost chopper unit connected to the load side terminal, in three main reactor constituting the main reactor during on of the auxiliary switch, the main mentioned above The bidirectional buck-boost chopper circuit according to claim 4, wherein a regenerative current is caused to flow in a direction opposite to the main current to one same main reactor different from the reactor. The chopper part is
A series connection of three main reactors equivalently constituting one reactor, one end of which is connected to the high potential side terminal of the DC power supply;
A main switch in which one pole is connected to the other end of the series connection body of the main reactor, and the other pole is directly connected to a low voltage terminal of the DC power supply;
A series connection body of an output diode and an output smoothing capacitor connected between both poles of the main switch,
A series connection body of a snubber diode and a snubber capacitor connected between both poles of the main switch,
An auxiliary switch connected between the connection point of the snubber diode and the snubber capacitor and the connection point of the series connection body of the two main reactors,
6. The auxiliary switch according to claim 1, wherein the voltage at the time of turning on the main switch is set to zero voltage or low voltage by setting the voltage of the snubber capacitor to zero voltage or low voltage. A bidirectional buck-boost chopper circuit according to one.   The auxiliary switch causes the electric charge accumulated in the output diode to flow through the main reactor on the DC power source side of the two main reactors in the direction opposite to the main current of the main reactor at the time of turn-on. The bidirectional buck-boost chopper circuit according to claim 6, wherein the bidirectional buck-boost chopper circuit is regenerated.   When the main switch is turned on, the regenerative resonance between the snubber capacitor and the main reactor connected to the DC power source side causes the electric charge accumulated in the snubber capacitor to be transferred to the main reactor on the DC power source side of the two main reactors. The bidirectional step-up / step-down chopper circuit according to claim 6, wherein the bidirectional current is supplied to the DC power source in a direction opposite to the main current of the main reactor and regenerated.   6. The main switch is turned on from the state of zero voltage and zero current or low voltage and low current by turning on the main switch after turning on the auxiliary switch. 8. The bidirectional buck-boost chopper circuit according to any one of 8.   The auxiliary switch is configured by a reverse blocking IGBT, a series connection of an IGBT with an antiparallel diode and a diode, or a series connection of an IGBT and a diode having no reverse blocking capability. Item 12. The bidirectional buck-boost chopper circuit according to any one of Items 9.

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