JP5310184B2 - Bidirectional buck-boost chopper circuit - Google Patents

Description

  The present invention provides a high-efficiency and high-power density power converter used in a fuel cell electric vehicle (hereinafter also referred to as FCEV), a hybrid vehicle (hereinafter also referred to as HEV), and an electric vehicle (hereinafter also referred to as EV). In particular, the present invention relates to prevention of generation of a surge voltage due to resonance and a soft switching circuit system.

  In electric vehicle-related fields such as FCEV, HEV, EV, etc., an inverter and a motor are driven using electric energy generating means such as a fuel cell and a battery. In this driving, the generated electric power is consumed during acceleration traveling and constant speed traveling, and the regenerative electric power of the motor is charged in an electric energy storage means such as a battery during deceleration traveling. Therefore, it is necessary to control the DC power flow in both directions between the power source and the load.

  In each operation region such as acceleration traveling, constant speed traveling, and deceleration traveling, the input / output voltage varies greatly depending on the operating conditions such as the state of the battery and the rotational speed of the motor. Therefore, since it is necessary to combine the step-up operation and the step-down operation, a bidirectional buck-boost chopper is used.

  2. Description of the Related Art Conventionally, a step-up / step-down chopper circuit that performs voltage step-up or step-down using a reactor is known. In this step-up / step-down operation, DC power is accumulated in the reactor by turning on and off switching elements such as IGBTs at high speed, and step-up / step-down is performed by outputting this DC power.

  As the operation of this switching element, a hard switching system and a soft switching system are known. In the hard switching system, there is a problem that the power loss is large because the time during which the voltage and current cross each other when the switching element is turned on or off is long. This switching loss increases as the switching frequency increases. As a fuel cell circuit using a hard switching system, for example, Patent Document 1 and Patent Document 2 are known.

  On the other hand, the soft switching method performs a switching operation in a state where the voltage or current is zero using a resonance phenomenon or the like, and thereby attempts to reduce power loss. Since high efficiency is required in the field of electric vehicles, a soft switching chopper circuit is required.

  Many soft switching type chopper circuits have been proposed. The circuit shown in FIG. 10 is an example of a conventionally proposed soft switching chopper circuit (Patent Document 3). FIG. 10 shows an example of a step-up chopper circuit, 107 is a DC reactor, 102 is an output diode, 103 is an output capacitor, and a main switch 111 is connected in parallel to the output capacitor 103.

  A series connection of a snubber capacitor 112 and a snubber diode 113 is connected in parallel to the main switch 111, and an auxiliary switch 104, a regenerative diode 105, and an auxiliary resonance reactor 106 are connected in series at an intermediate point between the snubber capacitor 112 and the snubber diode 113. One end of the body is connected. The other end of the series connection is connected to the positive voltage terminal of the input power supply 101. A feedback diode 108 is connected between a connection point between the regenerative diode 105 and the auxiliary resonant reactor 106 and the negative voltage terminal of the input power supply 101. The input power supply 101 is a DC input power supply.

  In such a circuit, the energy of the snubber capacitor 112 is transferred to the auxiliary resonant reactor 106 via the regenerative diode 105 by the operation of the auxiliary switch 104 energized in synchronization with the main switch 111. Thereafter, the energy transferred to the auxiliary resonance reactor 106 is regenerated to the power source 101 by a closed circuit formed by the auxiliary resonance reactor 106, the power source 101 and the feedback diode 108.

  However, since this conventional circuit regenerates the charged charge of the snubber capacitor 112 to the input power supply 101 by utilizing the resonance phenomenon, the step-up rate α (= Vout / Vin) which is the ratio of the output voltage Vout to the input voltage Vin is 2. In the region below 0, there is a non-soft switching region in which the charging voltage of the snubber capacitor 112 cannot be discharged to zero and a residual voltage is generated.

  FIG. 11 shows a soft switching region and a non-soft switching region, and FIG. 12 shows typical operation waveforms in the soft switching region and the non-soft switching region.

  In FIG. 11, a region indicated by (a) indicates a region where the boost rate α is 2.0 or more, and a region indicated by (b) and (c) indicates a region where the boost rate α is 2.0 to 1.0. ing. The boundary between region (b) and region (c) is determined by the load power.

This boundary region is determined by a complete discharge condition in which the voltage remaining in the snubber capacitor 112 is discharged and becomes completely zero, and the residual charge is smaller than the integral charge of the auxiliary switch current flowing during this period. From the conditions, the output voltage Vout is Vout> 2Vin−1 / 2 · (L / (C · Vin)) · (Pout / (Vin · η)) ²
It is expressed by the following formula. (Non-Patent Document 1)

  12 shows the voltage V112 of the snubber capacitor 112 and the current I111 of the main switch, FIG. 12A shows the voltage and current in the soft switching region, and FIGS. 12B and 12C show the non-soft. The voltage and current in the switching region are shown.

  The region (a) in FIG. 11 is a region where the step-up rate α is 2.0 or more. As shown in the relationship between the voltage and current in the soft switching region shown in FIG. 12 (a), the voltage of the snubber capacitor 112 due to the resonance phenomenon. V112 is completely discharged. By performing this complete discharge, when the main switch 111 is turned on and off, the switching operation is performed with zero voltage and zero current, and soft switching is achieved.

  A region (b) in FIG. 11 is a region where the step-up rate α is less than 2.0, and a residual voltage is generated in the voltage V112 of the snubber capacitor 112 as shown in FIG. 12 (b). Due to the generation of the residual voltage, the main switch 111 is turned on with a non-zero voltage and a non-zero current, and the turn-off becomes a non-soft switching region (b) in which a switching operation is performed with the zero voltage and the zero current.

  In addition, a region (c) in FIG. 11 is a region where the output is generated at a light load in a region where the step-up rate α is less than 2.0. In this region (c), as shown in FIG. 12 (c), a non-soft switching region (c) in which the main switch 111 is turned on and off with a non-zero voltage and a non-zero current is operated.

  As described above, the conventional circuit has a problem in that a non-soft switching region is generated due to the generation of the residual voltage of the snubber capacitor 112 and power loss occurs.

  Further, in the conventional circuit shown in FIG. 10, after the energy transferred to the auxiliary resonance reactor 106 is regenerated to the input power supply 101, a surge overvoltage is generated when the accumulated charge of the regenerative diode 105 is diode-recovered.

  FIG. 13A shows the current of the auxiliary switch 104, and FIG. 13B shows the voltage of the auxiliary switch 104.

  As shown in the voltage of FIG. 13B, the surge overvoltage Vp1 due to the stray capacitance of the auxiliary switch 104 and the resonance phenomenon of the auxiliary resonance reactor 106 is generated at both ends of the auxiliary switch 104 even when the main switch 111 is turned off.

  If the surge overvoltage due to the diode recovery of the regenerative diode 105 or the surge overvoltage due to the resonance phenomenon exceeds the rated voltage of the auxiliary switch 104 or the regenerative diode 105, the element may be damaged. In addition, even when the element is not directly damaged due to surge overvoltage, there is a possibility that the control circuit may malfunction due to surge overvoltage, or the gate circuit may malfunction and the main switch 111 or the auxiliary switch 104 may be damaged. is there.

  Further, in the conventional circuit shown in FIG. 10, since the output diode 102 is connected in series to the main circuit, there is a problem that power loss due to the forward voltage becomes large.

JP 2002-63923 A JP 2005-295671 A JP 2001-224165 A

Proceedings of the 2008 Annual Conference of the Institute of Electrical Engineers of Japan, 4-071, pp.117-118, 20083 / 19-21, “Operation characteristics outside the soft switching region in SAZZ converter”

  As described above, the conventionally proposed chopper circuit has the following problems of non-soft switching region, heat loss, and element damage.

  (1) Depending on the conditions of input / output voltage ratio and output power, there is a problem that a non-soft switching region occurs.

  (2) There is a problem that the control circuit may malfunction due to a surge overvoltage caused by reverse recovery (diode recovery) due to the stored charge of the regenerative diode, or noise caused by a surge overvoltage caused by stray capacitance of the auxiliary switch 104, resulting in element damage. is there.

In addition to the issues related to switching,
(3) There is a problem that the power loss due to the forward voltage of the output diode is large.

  Therefore, in the bidirectional buck-boost chopper circuit with low loss and high reliability, in addition to the above-mentioned problems related to switching, the problem related to the output diode is low loss and high reliability in the bidirectional buck-boost chopper circuit. It will be a hindrance in achieving this.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to solve problems related to switching of the bidirectional buck-boost chopper circuit and problems related to the output diode.

  In the solution of the problem related to the switching of the bidirectional buck-boost chopper circuit, the present invention can perform the entire soft switching in the operation region without causing the non-soft switching region due to the remaining snubber capacitor voltage even if the input / output voltage fluctuates An object is to provide a circuit system.

  An object of the present invention is to prevent overvoltage due to reverse recovery of a regenerative diode in solving a problem related to switching of a bidirectional buck-boost chopper circuit.

  An object of the present invention is to suppress overvoltage due to stray capacitance when an auxiliary switch is turned off in solving a problem related to switching of a bidirectional buck-boost chopper circuit.

  Another object of the present invention is to suppress power loss due to the forward voltage of the output diode.

  In order to achieve the above object, a bidirectional buck-boost chopper circuit according to the present invention includes a boost chopper unit that performs a boost operation and a step-down chopper that performs a buck operation in a bidirectional buck-boost chopper circuit that performs a boost operation and a buck operation bidirectionally. A part.

  The step-up chopper unit and the step-down chopper unit of the present invention include a main switch, a snubber capacitor and a snubber diode connected between both poles of the main switch, and a series connection body in which a diode, an auxiliary switch, and a saturable reactor are connected in series. The one end of the series connection body is connected to the connection point of the snubber capacitor and the snubber diode, the other end of the series connection body is connected to the DC power source, and the step-up ratio of the output voltage of the chopper section with respect to the voltage of the DC power source is 2 or more. And

  In the present invention, a series connection body in which a diode, an auxiliary switch, and a saturable reactor are connected in series is connected between a connection point between a snubber capacitor and a snubber diode and a DC power source, and the voltage accumulated in the snubber capacitor is converted to DC. When regenerating to the power supply, the voltage increase rate of the output voltage of the chopper section with respect to the voltage of the DC power supply is set to 2 or more, so that the residual voltage of the snubber capacitor becomes zero, and the non-existence due to the residual snubber capacitor voltage also depends on the fluctuation state of the input / output voltage. It is possible to enable the whole area soft switching in the operation area without generating the soft switching area.

  In addition, according to the present invention, a saturable reactor is connected in series to the diode and the auxiliary switch, thereby preventing overvoltage due to reverse recovery of the regenerative diode.

  Further, according to the present invention, by connecting a saturable reactor in series to the diode and the auxiliary switch, it is possible to suppress overvoltage due to stray capacitance when the auxiliary switch is turned off.

  The bidirectional buck-boost chopper circuit of the present invention can be configured by a four-quadrant chopper circuit formed by bridge-connecting chopper circuits or a two-quadrant chopper circuit.

  The four-quadrant chopper circuit of the present invention is a bidirectional step-up / step-down chopper circuit that performs a step-up operation and a step-down operation in both directions, and is parallel to the first and second DC power sources and the first and second DC power sources, respectively. First and second input capacitors connected to each other, a main reactor, an output capacitor connected in parallel to a load, two boost chopper units that perform a boost operation, and two step-down chopper units that perform a step-down operation are provided.

  The boost chopper unit included in the present invention includes a first boost chopper unit that performs a first boost operation and a second boost chopper unit that performs a second boost operation.

  The first step-up chopper unit of the present invention has a main switch in which one pole is connected to the negative voltage terminal of the second DC power supply and the other pole is connected to one end of the main reactor, and between both poles of the main switch. A series connection body of a connected snubber capacitor and a snubber diode, and a diode, an auxiliary switch, and a saturable reactor connected in series between the connection point of the snubber capacitor and the snubber diode and the midpoint of the DC power source divided into two. A first series connection body is provided.

  The second step-up chopper unit of the present invention has a main switch having one pole connected to the negative voltage terminal of the second DC power supply and the other pole connected to the other terminal of the main reactor, and both poles of the main switch A series connection of a snubber capacitor and a snubber diode connected in between, a diode connected between the connection point of the snubber capacitor and the snubber diode, and the midpoint of the DC power source divided into two, an auxiliary switch, and a saturable reactor in series A connected second series connection is provided.

  The step-down chopper unit included in the present invention includes a first step-down chopper unit that performs a first step-down operation and a second step-down chopper unit that performs a second step-down operation.

  The first step-down chopper unit of the present invention has a main switch in which one pole is connected to the positive voltage terminal of the first DC power source and the other pole is connected to one end of the main reactor, and between both poles of the main switch. A series connection body of a connected snubber capacitor and a snubber diode, and a diode, an auxiliary switch, and a saturable reactor connected in series between the connection point of the snubber capacitor and the snubber diode and the midpoint of the DC power source divided into two. A third series connection body is provided.

  The second step-down chopper unit of the present invention is connected between the main switch having one pole connected to the positive voltage terminal of the output capacitor and the other pole connected to the other terminal of the main reactor, and both poles of the main switch. A series connection of a snubber capacitor and a snubber diode, and a diode, an auxiliary switch and a saturable reactor connected in series between the connection point of the snubber capacitor and the snubber diode and the positive voltage terminal of the first DC power supply. A fourth series connection body.

  Each auxiliary switch included in each chopper unit of the present invention is turned on before the main switch to perform the switching operation of the main switch at zero voltage and zero current.

  One form of the two-quadrant chopper circuit of the present invention is a bidirectional step-up / step-down chopper circuit that includes a first step-up chopper unit and a first step-down chopper unit and performs a step-up operation and a step-down operation in both directions. A second DC power source, first and second input capacitors connected in parallel to the first and second DC power sources, a main reactor, an output capacitor connected in parallel to the load, and a boost operation; A step-up chopper unit that performs the step-down operation and a step-down chopper unit that performs the step-down operation;

  The step-up chopper unit of this embodiment has a main switch in which one pole is connected to the negative voltage terminal of the second DC power supply and the other pole is connected to one end of the main reactor, and a snubber connected between both poles of the main switch. A series connection body of a capacitor and a snubber diode, and a booster side series in which a diode, an auxiliary switch, and a saturable reactor are connected in series between a connection point of the snubber capacitor and the snubber diode and an intermediate point of the DC power source divided into two. A connecting body is provided.

  The step-down chopper unit of this embodiment has a main switch in which one pole is connected to the positive voltage terminal of the first DC power supply and the other pole is connected to one end of the main reactor, and a snubber connected between both poles of the main switch. A series-connected body of a capacitor and a snubber diode, and a step-down-side series in which a diode, an auxiliary switch, and a saturable reactor are connected in series between the connection point of the snubber capacitor and the snubber diode and the midpoint of the divided DC power supply A connecting body is provided.

  Each auxiliary switch of each chopper unit of this form is turned on before the main switch, so that the switching operation of the main switch is performed at zero voltage and zero current.

  In the above embodiment, the two-quadrant chopper circuit of the present invention can be configured with a single saturable reactor by sharing the saturable reactor of the first step-up chopper section and the saturable reactor of the first step-down chopper section. In this configuration, the saturable reactor included in the step-up side series connection body and the saturable reactor included in the step-down side series connection body are configured as one common saturable reactor, and a DC power source in which one end of the saturable reactor is divided into two Connect to the middle point.

  Another form of the two-quadrant chopper circuit of the present invention is a bidirectional step-up / step-down chopper circuit that includes a second step-up chopper unit and a second step-down chopper unit and performs a step-up operation and a step-down operation in both directions. And a second DC power source, first and second input capacitors connected in parallel to the first and second DC power sources, a main reactor, an output capacitor connected in parallel to the load, and a boost operation And a step-down chopper unit that performs a step-down operation.

  The boost chopper of this form is connected between the main switch having one pole connected to the negative voltage terminal of the second DC power supply and the other pole connected to the other terminal of the main reactor, and both poles of the main switch. Booster in which a series connection of a snubber capacitor and a snubber diode, a diode connected between the connection point of the snubber capacitor and the snubber diode, and an intermediate point of the divided DC power source, an auxiliary switch, and a saturable reactor are connected in series A side series connection body is provided.

  The step-down chopper unit in this form has a main switch having one pole connected to the positive voltage terminal of the output capacitor and the other pole connected to the other terminal of the main reactor, and a snubber capacitor connected between both poles of the main switch. And a series connection body of a snubber diode, and a step-down side series circuit in which a diode, an auxiliary switch, and a saturable reactor are connected in series between a connection point of a snubber capacitor and a snubber diode and a positive voltage terminal of the first DC power supply A connecting body.

  Each auxiliary switch of each chopper unit of this form is turned on before the main switch, so that the switching operation of the main switch is performed at zero voltage and zero current.

  The bidirectional buck-boost chopper circuit according to the present invention comprises a semiconductor switch as a main switch, a body diode connected in reverse parallel to the semiconductor switch as an output diode, and a semiconductor switch while the main current is flowing through the body diode. Synchronous rectification to control on.

  This synchronous rectification can suppress power loss due to the forward voltage of the output diode.

  In the bidirectional buck-boost chopper circuit according to the present invention, the first DC power source and the second DC power source divide one DC power source into two parts, and the first input capacitor and the second input between the two divided terminals. Capacitors can be connected in parallel.

  According to the aspect of the present invention, the switching operation of the main switch can be performed with zero voltage and zero current by the action of the auxiliary switch over the entire operation region.

  Further, according to the aspect of the present invention, the saturable reactor can prevent overvoltage due to reverse recovery of the regenerative diode, and can suppress overvoltage due to stray capacitance when the auxiliary switch is turned off.

  In addition, according to the aspect of the present invention, the semiconductor switch is configured with, for example, a power MOSFET, and the forward voltage of the antiparallel diode can be reduced by synchronous rectification of the semiconductor switch, thereby reducing the power loss.

  According to the present invention, the bidirectional buck-boost chopper circuit can be soft-switched in the entire region, the loss can be reduced, the overvoltage can be suppressed, and a low-loss and high-reliability power conversion device can be configured.

  According to the present invention, in solving the problem related to the switching of the bidirectional buck-boost chopper circuit, the entire soft switching is performed in the operation region without causing the non-soft switching region due to the remaining snubber capacitor voltage even if the input / output voltage fluctuates. Can be possible.

  According to the present invention, overvoltage due to reverse recovery of the regenerative diode can be prevented in solving the problem related to switching of the bidirectional buck-boost chopper circuit.

  According to the present invention, in solving the problem related to switching of the bidirectional buck-boost chopper circuit, it is possible to suppress overvoltage due to stray capacitance when the auxiliary switch is turned off.

  Further, according to the present invention, power loss due to the forward voltage of the output diode can be suppressed.

It is a figure for demonstrating the step-up chopper circuit and step-down chopper circuit with which the bidirectional | two-way buck-boost chopper circuit of this invention is provided. It is a circuit diagram for demonstrating the 1st form of this invention. It is an equivalent circuit diagram in each operation mode of the 1st form of this invention. It is an operation | movement time chart of the 1st form of this invention. It is a figure for demonstrating suppression of the surge overvoltage of the auxiliary switch of this invention. It is a figure for demonstrating the surge overvoltage of the regeneration diode of this invention. It is a circuit diagram for demonstrating the 2nd form of this invention. It is a circuit diagram for demonstrating the 3rd form of this invention. It is a circuit diagram for demonstrating the 4th form of this invention. It is a circuit diagram for demonstrating the example of a conventional circuit. It is a figure for demonstrating the soft switching area | region and non-soft switching area | region of a conventional circuit. It is a figure for demonstrating the difference in the circuit operation | movement in the soft switching area | region and non-soft switching area | region of a conventional circuit. It is a figure which shows the surge overvoltage of the auxiliary switch of the conventional circuit. It is a figure which shows the surge overvoltage of the regeneration diode of the conventional circuit.

  Embodiments of the present invention will be described with reference to the drawings.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram for explaining a step-up chopper circuit and a step-down chopper circuit included in a bidirectional buck-boost chopper circuit according to the present invention.

  FIG. 1A is a circuit example of a step-up chopper circuit provided in the bidirectional buck-boost chopper circuit of the present invention.

  The step-up chopper unit connects one pole of the main switch 10 to the negative voltage terminal of the second DC power source 1b and connects the other pole to the positive voltage terminal of the first DC power source 1a. A series connection body of the snubber capacitor 20 and the snubber diode 30 is connected between the two poles, and a connection point between the snubber capacitor 20 and the snubber diode 30 and an intermediate point between the first DC power source 1a and the second DC power source 1b. A first series connection body 70 in which an auxiliary switch 40, a regenerative diode 50 and a saturable reactor 60 are connected in series is connected between them, and one pole of the main switch 10 is connected to the main reactor 7 and the main switch of the step-down chopper section. Connect to output through body diode.

  The electric charge of the snubber capacitor 20 is resonantly discharged to the second DC power source 1b. At this time, since the voltage of the second DC power supply 1b is ½ of the output voltage Vout, the snubber capacitor 20 is completely discharged and no residual voltage exists, so that a soft switching operation can always be performed.

  Further, the saturable reactor 60 provided in the first series connection body 70 bears a surge overvoltage caused by reverse recovery of the accumulated charge of the regenerative diode 50 and a surge overvoltage caused by the stray capacitance of the auxiliary switch 40, and the auxiliary switch 40 and the regenerative diode 50. It is possible to reduce the voltage applied to the element and prevent the element from being damaged.

  FIG. 1B is a circuit example of the step-down chopper circuit provided in the bidirectional buck-boost chopper circuit of the present invention.

  The step-down chopper unit connects one pole of the main switch 10 to the positive voltage terminal of the first DC power source 1a, and connects the other pole to the negative polarity of the DC power source 1b via the body diode of the main switch of the step-up chopper unit. Connect to the voltage terminal.

  A series connection body of a snubber capacitor 20 and a snubber diode 30 is connected between both poles of the main switch 10, and a connection point between the snubber capacitor 20 and the snubber diode 30 and an intermediate point between the first DC power source 1a and the second DC power source 1b. The first series connection body 70 in which the auxiliary switch 40, the regenerative diode 50, and the saturable reactor 60 are connected in series is connected between the two points, and the other pole of the main switch 10 is connected to the output terminal via the main reactor 7. Connect to.

  The electric charge of the snubber capacitor 20 is resonantly discharged to the second DC power source 1b. At this time, since the voltage of the second DC power supply 1b is ½ of the output voltage Vout, the snubber capacitor 20 is completely discharged and no residual voltage exists, so that a soft switching operation can always be performed.

  Further, the saturable reactor 60 provided in the first series connection body 70 bears a surge overvoltage caused by reverse recovery of the accumulated charge of the regenerative diode 50 and a surge overvoltage caused by the stray capacitance of the auxiliary switch 40, and the auxiliary switch 40 and the regenerative diode 50. It is possible to reduce the voltage applied to the element and prevent the element from being damaged.

  Further, by configuring the body diode of the main switch 10 as an output diode and synchronously rectifying the main switch 10, power loss due to the forward voltage of the main switch 10 can be reduced.

  Next, a circuit example of a four-quadrant chopper circuit will be described with reference to FIG. In FIG. 2, 3 is an output capacitor, 5 is a load, 7 is a DC reactor, 11, 12, 13, and 14 are main switches, 21, 22, 23, and 24 are snubber capacitors, and 31, 32, 33, and 34 are snubber diodes. , 41, 42, 43, 44 are auxiliary switches, 51, 52, 53, 54 are regenerative diodes, and 61, 62, 63, 64 are saturable reactors.

  The main switches 11 to 14 are made of semiconductor devices such as IGBTs and MOSFETs. The auxiliary switches 41 to 44, the regenerative diodes 51 to 54, and the saturable reactors 61 to 64 constitute an auxiliary resonance circuit.

  In FIG. 2, the bidirectional buck-boost chopper circuit includes two step-up chopper units A and B and two step-down chopper units C and D.

  The first step-up chopper A includes a first series connection body 73 including a main switch 13, a snubber capacitor 23, a snubber diode 33, and an auxiliary switch 43, a regenerative diode 53, and a saturable reactor 63.

  The second step-up chopper part B includes a second series connection body 71 including a main switch 11, a snubber capacitor 21, a snubber diode 31, and an auxiliary switch 41, a regenerative diode 51, and a saturable reactor 61.

  The first step-down chopper C constitutes a third series connection body 74 including the main switch 14, the snubber capacitor 24, the snubber diode 34, and the auxiliary switch 44, the regenerative diode 54, and the saturable reactor 64.

  The second step-down chopper part D includes a fourth series connection body 72 including the main switch 12, the snubber capacitor 22, the snubber diode 32, and the auxiliary switch 42, the regenerative diode 52, and the saturable reactor 62.

  The bidirectional buck-boost chopper circuit includes a first DC power source 1a and a second DC power source 1b obtained by dividing the DC power source into two, and a first input capacitor 4a is connected in parallel to the first DC power source 1a. Are connected in parallel to the second DC power source 1b.

  Between the DC power supplies 1a and 1b, a first step-down chopper unit C and a first step-up chopper unit A, a second step-down chopper unit D and a second step-up chopper unit B are connected in series to form a bridge circuit. A main reactor which is a direct current reactor between an intermediate point between the first step-down chopper part C and the first step-up chopper part A and an intermediate point between the second step-down chopper part D and the second step-up chopper part B 7 is connected.

  An output capacitor 3 connected in parallel to the load 5 is provided on the output side of the bidirectional buck-boost chopper circuit.

  The first step-up chopper unit A that performs the first step-up operation has a main switch 13 in which one pole is connected to the negative voltage terminal of the second DC power source 1 b and the other pole is connected to one end of the main reactor 7. And a series connection body of a snubber capacitor 23 and a snubber diode 33 connected between both poles of the main switch 13, a connection point between the snubber capacitor 23 and the snubber diode 33, and an intermediate point between the two divided DC power sources 1a and 1b. A regenerative diode 53, an auxiliary switch 43, and a saturable reactor 63 connected in series to each other.

  The second boost chopper B that performs the second boost operation has one main connected to the negative voltage terminal of the second DC power supply 1b and the other connected to the other terminal of the main reactor 7. A switch 11, a series connection body of a snubber capacitor 21 and a snubber diode 31 connected between both poles of the main switch 11, a connection point between the snubber capacitor 21 and the snubber diode 31, and an intermediate point between the DC power supplies 1a and 1b divided in two. A regenerative diode 51, an auxiliary switch 41, and a saturable reactor 61 connected in series are connected in series.

  The first step-down chopper C that performs the first step-down operation has a main switch 14 having one pole connected to the positive voltage terminal of the first DC power source 1 a and the other pole connected to one end of the main reactor 7. And a series connection body of a snubber capacitor 24 and a snubber diode 34 connected between both poles of the main switch 14, a connection point of the snubber capacitor 24 and the snubber diode 34, and an intermediate point of the DC power supplies 1a and 1b divided in two. A third series connection body 74 in which a regenerative diode 54, an auxiliary switch 44, and a saturable reactor 64 connected in series are connected in series.

  The second step-down chopper unit D that performs the second step-down operation includes a main switch 12 having one pole connected to the positive voltage terminal of the output capacitor 3 and the other pole connected to the other terminal of the main reactor 7. , Connected in series between the snubber capacitor 22 and the snubber diode 32 connected between the two poles of the main switch 12, and the connection point between the snubber capacitor 22 and the snubber diode 32 and the positive voltage terminal of the first DC power source 1a. And a fourth series connection body 72 in which the regenerative diode 52, the auxiliary switch 42, and the saturable reactor 62 are connected in series.

  The auxiliary switches 43, 44, 41, and 42 included in the chopper units A, B, C, and D are turned on before the main switches 11, 12, 13, and 14 to turn on the main switches 11, 12, 13, and 14, respectively. The switching operation is performed at zero voltage and zero current.

  Hereinafter, an operation example of the bidirectional buck-boost chopper circuit will be described with reference to an equivalent circuit in each operation mode shown in FIG. 3 and an operation waveform diagram of each part in FIG. Here, the second step-up chopper B will be described.

[Operation mode 1]
FIG. 3A is an equivalent circuit showing the operation mode 1 at time points -t3 to -t2 in FIG. The gate signal Vg41 of the auxiliary switch 41 is supplied a predetermined very short time before the gate signal of the main switch 11. As a result, the auxiliary switch 41 is turned on before the main switch 11, and a voltage difference between the output voltage Vo and the input voltage 1/2 · Vin is applied to the saturable reactor 61 with the polarity shown in the figure.

  During this period, since the inductance of the saturable reactor 61 is a large inductance L0 before saturation, almost no current flows through the saturable reactor 61.

[Operation mode 2]
When the saturable reactor 61 is saturated at the time point -t2, the next operation mode 2 shown in FIG. In the operation mode 2 from the time point -t2 to -t1, the current of the saturable reactor 61 is linearly obtained by dividing the input / output voltage difference (Vo-1 / 2 · Vin) by the inductance L1 after saturation of the saturable reactor 61. When I61 rises and reaches the current I7 of the main reactor 7, and the reverse parallel diode of the main switch 12 reversely recovers and turns off, the operation mode 2 ends at the time point -t1, and the next operation mode 3 in FIG. Become.

[Operation mode 3]
The snubber capacitor 21 is discharged from the time point -t1, and the saturable reactor 61 has a sinusoidal waveform as indicated by I61 in FIG. Current flows.

  When the voltage of the snubber capacitor 61 becomes zero at time t0, the gate signal Vg11 is supplied to the main switch 11 as shown in FIG.

[Operation mode 4]
During time t0 to t1 in this operation mode 4, the energy transferred to the saturable reactor 61 is regenerated to the power source 1b and becomes zero.

  By the operations in the above operation modes 1 to 4, the main switch 11 is turned on with zero voltage and zero current. Further, since the electric charge of the snubber capacitor 21 becomes a resonant discharge to the half voltage power source of the input DC power source divided into two, it is completely discharged and the voltage does not remain and can always operate by soft switching.

  FIG. 14 shows an overvoltage Vr1 due to reverse recovery of the regenerative diode 105 that occurred at the time t1 when the resonance phenomenon ends in the conventional circuit example shown in FIG.

  On the other hand, in the configuration shown in FIG. 2 of the present invention, since the saturable reactor 61 is used instead of the conventional auxiliary reactor 106 shown in FIG. 10, the reverse recovery current − of the regenerative diode 105 of FIG. Since i105 is blocked by the saturable reactor 61 of the present invention as shown in FIG. 6, overvoltage due to reverse recovery of the regenerative diode 51 is suppressed. The improved waveform of the regenerative diode 51 is indicated by Vr2 in FIG.

  Similarly, FIG. 13 shows an overvoltage Vp1 due to the stray capacitance of the auxiliary switch 104 that occurred at the time t2 when the auxiliary switch 104 was turned off in the conventional circuit example shown in FIG.

  On the other hand, in the configuration shown in FIG. 2 of the present invention, the saturable reactor 61 is used in place of the conventional auxiliary reactor 106 shown in FIG. 10, so that it is generated by the stray capacitance of the auxiliary switch 104 of FIG. Since the current i104 of the auxiliary switch 104 is blocked by the saturable reactor 61 of the present invention as shown in FIG. 5, the overvoltage due to the stray capacitance of the auxiliary switch 41 is suppressed to Vp2. The improved waveform of the auxiliary switch 41 is indicated by Vp2 in FIG.

  Next, another embodiment of the bidirectional buck-boost chopper circuit of the present invention will be described with reference to FIGS.

  FIG. 7 shows an example in which two chopper parts, a first step-up chopper part A and a first step-down chopper part B, are configured. In the configuration shown in FIG. 7, the forward step-down operation is performed by the first step-down chopper unit C, and the reverse step-up operation is performed by using the first step-up chopper unit A.

  The configuration shown in FIG. 8 is a configuration in which a saturable reactor 65 in which the saturable reactor 63 and the saturable reactor 64 of the auxiliary circuit of the two chopper units are shared is used as the saturable reactor 65 in the configuration shown in FIG.

  FIG. 9 shows an example in which two chopper parts, a second step-up chopper part B and a fourth step-down chopper part D, are configured. In the configuration shown in FIG. 9, the forward step-down operation is performed by the second step-down chopper unit D, and the reverse step-up operation is performed by using the second step-up chopper unit B.

  Further, the saturable reactor is not a single reactor having a saturable characteristic, but two serially connected bodies of one saturable reactor having an inductance L0 before saturation and a reactor having an inductance L1 after saturation. It may be configured.

  Furthermore, the semiconductor switch element is composed of MOSFET, and the main current is supplied by the synchronous rectification to supply the gate drain voltage while passing through the antiparallel diode, thereby controlling the forward voltage and the power loss. May be.

1a, 1b DC power supply 3 Output capacitor 4a, 4b Input capacitor 5 Load 7 Main reactor 10, 11, 12, 13, 14 Main switch 20, 21, 22, 23, 24 Snubber capacitor 30, 31, 32, 33, 34 Snubber Diode 40, 41, 42, 43, 44 Auxiliary switch 50, 51, 52, 53, 54 Regenerative diode 60, 61, 62, 63, 64, 65 Saturable reactor 70, 71, 72, 73, 74 Series connection body 101 Input power supply 102 Output diode 103 Output capacitor 104 Auxiliary switch 105 Regenerative diode 106 Auxiliary reactor 107 DC reactor 108 Feedback diode 111 Main switch 112 Snubber capacitor 113 Snubber diode A, B Step-up chopper unit C, D Step-down chopper unit

Claims (7)

In a bidirectional buck-boost chopper circuit that performs a boost operation and a buck operation bidirectionally,
A step-up chopper unit that performs a step-up operation and a step-down chopper unit that performs a step-down operation are provided.
The step-up chopper part and the step-down chopper part are
A snubber capacitor and a snubber diode connected between both poles of the main switch and the main switch;
A series connection body in which a diode, an auxiliary switch, and a saturable reactor are connected in series;
One end of the series connection body is connected to a connection point between the snubber capacitor and the snubber diode, and the other end of the series connection body is connected to a DC power source,
2. A bidirectional step-up / step-down chopper circuit, wherein the step-up ratio of the output voltage of the chopper unit with respect to the voltage of the DC power supply is 2 or more. In a bidirectional buck-boost chopper circuit that performs a boost operation and a buck operation bidirectionally,
First and second DC power supplies;
First and second input capacitors connected in parallel to the first and second DC power sources, respectively;
The main reactor,
An output capacitor connected in parallel to the load;
Two boost chopper units for performing a boost operation and two step-down chopper units for performing a step-down operation are provided.
The first boost chopper unit that performs the first boost operation is:
A main switch having one pole connected to the negative voltage terminal of the second DC power supply and the other pole connected to one end of the main reactor;
A series connection body of a snubber capacitor and a snubber diode connected between both poles of the main switch;
A first series connection body in which a diode, an auxiliary switch, and a saturable reactor are connected in series between a connection point of the snubber capacitor and the snubber diode and an intermediate point of the divided DC power supply;
The second boost chopper unit that performs the second boost operation is:
A main switch having one pole connected to the negative voltage terminal of the second DC power supply and the other pole connected to the other terminal of the main reactor;
A series connection body of a snubber capacitor and a snubber diode connected between both poles of the main switch;
A second series connection body in which a diode, an auxiliary switch, and a saturable reactor are connected in series between a connection point between the snubber capacitor and the snubber diode and an intermediate point between the two divided DC power sources;
The first step-down chopper unit that performs the first step-down operation is:
A main switch having one pole connected to the positive voltage terminal of the first DC power supply and the other pole connected to one end of the main reactor;
A series connection body of a snubber capacitor and a snubber diode connected between both poles of the main switch;
A third series connection body in which a diode connected between the connection point of the snubber capacitor and the snubber diode and an intermediate point of the divided DC power source, an auxiliary switch, and a saturable reactor are connected in series;
The second step-down chopper unit that performs the second step-down operation is:
A main switch having one pole connected to the positive voltage terminal of the output capacitor and the other pole connected to the other terminal of the main reactor;
A series connection body of a snubber capacitor and a snubber diode connected between both poles of the main switch;
A diode connected between a connection point of the snubber capacitor and the snubber diode and a positive voltage terminal of the first DC power source, a fourth series connection body in which an auxiliary switch and a saturable reactor are connected in series;
Each of the auxiliary switches included in each of the chopper units is turned on before the main switch, so that the switching operation of the main switch is performed with zero voltage and zero current. In a bidirectional buck-boost chopper circuit that performs a boost operation and a buck operation bidirectionally,
First and second DC power supplies;
First and second input capacitors connected in parallel to the first and second DC power sources, respectively;
The main reactor,
An output capacitor connected in parallel to the load;
A step-up chopper unit that performs step-up operation and a step-down chopper unit that performs step-down operation are provided.
The step-up chopper part is
A main switch having one pole connected to the negative voltage terminal of the second DC power supply and the other pole connected to one end of the main reactor;
A series connection body of a snubber capacitor and a snubber diode connected between both poles of the main switch;
A step-up-side series connection body in which a diode, an auxiliary switch, and a saturable reactor connected in series between a connection point of the snubber capacitor and the snubber diode and an intermediate point of the two divided DC power sources;
The step-down chopper part is
A main switch having one pole connected to the positive voltage terminal of the first DC power supply and the other pole connected to one end of the main reactor;
A series connection body of a snubber capacitor and a snubber diode connected between both poles of the main switch;
A step-down-side series connection body in which a diode, an auxiliary switch, and a saturable reactor are connected in series between a connection point of the snubber capacitor and the snubber diode and an intermediate point of the divided DC power supply;
Each of the auxiliary switches included in each of the chopper units is turned on before the main switch, so that the switching operation of the main switch is performed with zero voltage and zero current. The saturable reactor included in the step-up side series connection body and the saturable reactor included in the step-down side series connection body are configured by a single saturable reactor,
The bidirectional buck-boost chopper circuit according to claim 3, wherein one end of the saturable reactor is connected to an intermediate point of a DC power source divided into two. In a bidirectional buck-boost chopper circuit that performs a boost operation and a buck operation bidirectionally,
First and second DC power supplies;
First and second input capacitors connected in parallel to the first and second DC power sources, respectively;
The main reactor,
An output capacitor connected in parallel to the load;
A step-up chopper unit that performs step-up operation and a step-down chopper unit that performs step-down operation are provided.
The boost chopper is
A main switch having one pole connected to the negative voltage terminal of the second DC power supply and the other pole connected to the other terminal of the main reactor;
A series connection body of a snubber capacitor and a snubber diode connected between both poles of the main switch;
A step-up-side series connection body in which a diode, an auxiliary switch, and a saturable reactor connected in series between a connection point of the snubber capacitor and the snubber diode and an intermediate point of the two divided DC power sources;
The step-down chopper is
A main switch having one pole connected to the positive voltage terminal of the output capacitor and the other pole connected to the other terminal of the main reactor;
A series connection body of a snubber capacitor and a snubber diode connected between both poles of the main switch;
A step-down-side series connection body in which a diode connected between a connection point of the snubber capacitor and the snubber diode and a positive voltage terminal of the first DC power supply, an auxiliary switch, and a saturable reactor are connected in series;
Each of the auxiliary switches included in each of the chopper units is turned on before the main switch, so that the switching operation of the main switch is performed with zero voltage and zero current. The main switch is composed of a semiconductor switch, and a body diode connected in reverse parallel to the semiconductor switch is used as an output diode.
6. The bidirectional buck-boost chopper circuit according to claim 1, wherein synchronous rectification is performed to turn on the semiconductor switch while a main current is flowing through a body diode.   The first DC power source and the second DC power source are obtained by dividing one DC power source into two, and connecting the first input capacitor and the second input capacitor in parallel between the two divided terminals, respectively. The bidirectional buck-boost chopper circuit according to any one of claims 2 to 6, wherein the bidirectional buck-boost chopper circuit is characterized.