JP6729196B2 - Power converter - Google Patents

Description

The present invention relates to a power conversion device.

A system including two strings is known as a power system that supplies power from M power sources to a load (Patent Document 1). In this power system, the two strings include M power sources (M is an integer greater than 1) and switching circuits electrically connected to the M power sources. The switching circuit is composed of a DCDC converter. Each DCDC converter is connected in series. A string optimizer is connected between the common DC bus connected to the load and the two strings.

Special table 2013-536512 gazette

However, in the above power system, there is a problem that the loss is increased due to the addition of the string optimizer in order to increase the boost ratio.

The problem to be solved by the present invention is to provide a power conversion device that suppresses loss.

The present invention includes a primary side circuit having an input port and a secondary side circuit having a plurality of output ports and a plurality of secondary side conversion circuits, and a plurality of output ports are connected in series to form a primary side circuit. And the secondary side circuit are insulated, and the operating point of the power supply is controlled so as to increase the input power from the power supply. Then, the present invention solves the above problem by outputting the input power of the power supply when operating at the operating point to each of the plurality of secondary side conversion circuits.

According to the present invention, there is an effect that power can be converted while suppressing loss.

FIG. 1 is a circuit diagram of a power conversion system according to this embodiment. FIG. 2 is a graph of voltage-current characteristics of the power supply shown in FIG. FIG. 3 is a circuit diagram of the first-stage DCDC converter in the circuit configuration of the power conversion system of FIG. FIG. 4 is a graph showing current characteristics and voltage characteristics in the DCDC converter shown in FIG. FIG. 5 is a graph showing the characteristics of the phase difference, the excitation time, the outputs (V _ref , I _ref ) of the rectifier and the output voltage (V _out ) of the secondary side conversion circuit in the DCDC converter shown in FIG. FIG. 6 is a circuit diagram of the power conversion system according to the present embodiment. FIG. 7 shows a circuit diagram between a power supply and an output port in a power conversion system according to another embodiment of the present invention.

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

<<1st Embodiment>>
The power conversion device according to this embodiment will be described with reference to FIG. FIG. 1 is a circuit diagram of a power conversion system including a power conversion device 200 according to this embodiment. The power conversion device 200 according to the present embodiment converts the power input from the power supply and supplies the converted power to the load. The power converter is used, for example, in a charging system mounted on a vehicle. Note that, in the following description, the embodiment will be described with a power source being a solar cell and a load being a secondary battery. The power source is not limited to the solar cell and may be another power source. The load is not limited to the secondary battery, but may be a device such as an air conditioner. The power conversion device does not necessarily have to be mounted on the vehicle, and may be mounted on a device other than the vehicle.

As shown in FIG. 1, the power conversion system according to this embodiment includes a plurality of power sources 1, 2, a load 3, and a power conversion device 200. The power sources 1 and 2 are solar cells. Since the power sources 1 and 2 are solar cells, the power that can be output (generated power) from the power sources 1 and 2 differs depending on the intensity of the light that strikes the batteries 1 and 2 (sunlight amount). The power supply 1 and the power supply 2 are respectively connected to the input side of the power conversion device 200 by a pair of power supply lines. That is, the power supply line connecting between the power supply 1 and the input of the power conversion device 200 and the power supply line connecting between the power supply 2 and the input of the power conversion device are independent from each other. Therefore, the power supply 1 can output the outputtable power of the power supply 1 without depending on the outputtable power of the power supply 2. The power supply 2 can output the outputtable power of the power supply 2 without depending on the outputtable power of the power supply 1.

Here, unlike the present embodiment, a case where the power source 1 and the power source 2 are connected in series will be described. For example, when a part of the battery 1 is shaded so that the intensity of light hitting the power source 1 becomes smaller than the intensity of light hitting the power source 2, the power that can be output by the power source 1 can be output by the power source 2. Less than power. As a characteristic of the solar cell, the output voltage of the power supplies 1 and 2 becomes lower as the available output power becomes smaller. Since the power source 2 having high outputtable power is connected in series to the power source 1 having low outputtable power, the output current of the power source 2 is suppressed to the output current of the power source 1. Therefore, the outputtable electric power of the power supplies 1 and 2 as a whole is significantly reduced. On the other hand, in the present embodiment, since the power source 1 and the power source 2 are connected to the power conversion device by separate power source lines without connecting the power source 1 and the power source 2 in series, the power source 1 and the power source 2 are mutually connected. Outputtable power can be output independently of each other.

The load 3 is a load such as a battery. The power conversion device 200 is a DCDC conversion device having a one-time boosting function while controlling the power supplies 1 and 2 so that the power supplies 1 and 2 operate at an operating point where high output power is obtained.

The power conversion device 200 includes a primary circuit 10 and a secondary circuit 30. The primary side circuit 10 is a primary side circuit of a DCDC conversion circuit (DCDC converter), and the secondary side circuit 30 is a secondary side circuit of a DCDC converter. The primary side circuit 10 converts direct current input from the power supplies 1 and 2 into alternating current. A transformer is provided between the primary circuit 10 and the secondary circuit 30 so that the primary circuit 10 and the secondary circuit are insulated from each other. Also, this transformer exerts a boosting function. The secondary circuit 30 rectifies the boosted AC into DC and supplies the DC to the load 3. Of the primary side circuit 10, DCAC conversion circuits correspond to primary side conversion circuits 11 to 14 described later, and ACDC conversion circuits of the secondary side circuit 30 correspond to secondary side conversion circuits 61 to 64 described later. Equivalent to.

The circuit configuration on the primary side will be described. The primary side circuit 10 includes primary side conversion circuits 11 to 14, primary windings 15 to 18, input ports 19 and 20, and smoothing capacitors 21 and 22.

The primary side conversion circuits 11 to 14 are full bridge circuits in which switching elements S1 to S4 are connected in a full bridge shape, and convert the DC input voltage input from the power sources 1 and 2 into an AC voltage. In the switching device S ₁ to S _4, as conduction direction of the conduction direction and a reflux diode of the transistor are opposite to each other, the transistor and the reflux diode are connected in parallel. IGBT, MOSFET, etc. are used for a transistor. The free wheeling diode is a rectifying element or a parasitic diode of a MOSFET. The switching element S ₁ and the switching element S ₂ are connected in series between a pair of power supply lines, and the switching element S ₃ and the switching element S ₄ are connected in series between the same power supply lines. A series circuit of switching element S ₁ and switching element S ₂ converts the DC voltage of the power supply 1 into an AC voltage by a switching operation, alternating current from the connecting point O ₁ between the switching element S ₁ and switching element S ₂ Output voltage. Similarly, a series circuit between the switching element S ₃ and the switching element S ₄ converts the DC voltage of the power supply 1 into an AC voltage by a switching operation, the connection point of the switching elements S ₃ and the switching element S ₄ O _The AC voltage is output from ₂ . That is, the connection point O ₁ is an output terminal for one AC voltage, and the connection point O ₂ is an output terminal for the other AC voltage.

The input of the primary side conversion circuit 11 is connected to the power supply 1 in parallel. The output of the primary side conversion circuit 11 is connected to the primary winding 15. The input of the primary side conversion circuit 12 is connected to the power supply 1 in parallel. The output of the primary side conversion circuit 12 is connected to the primary winding 16. That is, the plurality of primary side conversion circuits 11 and 12 are connected in parallel to the same power supply 1.

The input of the primary side conversion circuit 13 is connected to the power supply 2 in parallel. The output of the primary side conversion circuit 13 is connected to the primary winding 17. The input of the primary side conversion circuit 13 is connected to the power supply 2 in parallel. The output of the primary side conversion circuit 13 is connected to the primary winding 18. That is, the plurality of primary side conversion circuits 13 and 14 are connected in parallel to the same power supply 2. Further, the plurality of primary side conversion circuits 11 and 12 and the plurality of primary side conversion circuits 13 and 14 are not directly connected.

The primary windings 15 to 18 are coils on the primary side of the transformer. The primary windings 15 and 16 are coils for supplying the power that can be output from the power source 1 to the secondary side, and correspond to the power source 1 and the primary side conversion circuits 11 and 12. The primary windings 17 and 18 are coils for supplying the power that can be output from the power source 2 to the secondary side, and correspond to the power source 1 and the primary side conversion circuits 13 and 14. One end of the primary winding 15 is connected to the output terminal (connection point Q ₁ ) of the primary side conversion circuit 11, and the other end of the primary winding 15 is the output terminal of the primary side conversion circuit 11 ( It is connected to the connection point Q ₂ ). One end of the primary winding 16 is connected to the output terminal (connection point Q ₁ ) of the primary side conversion circuit 12, and the other end of the primary winding 16 is the output terminal of the primary side conversion circuit 12 ( It is connected to the connection point Q ₂ ).

The connection between the primary winding 17 and the primary side conversion circuit 13 and the connection between the primary winding 18 and the primary side conversion circuit 14 are the primary winding 15 and the primary side conversion circuit. Since it is the same as the connection with 11, the description is omitted.

The input port 19 is a terminal for connecting the power supply 1 to the primary side circuit 10. The input port 20 is a terminal for connecting the power supply 2 to the primary side circuit 10. The input port 19 has a pair of terminals 19a and 19b, and is connected to the positive side of the terminal 19a power supply 1 and to the negative side of the terminal 19b power supply 1. Like the input port 19, the input port 20 has a positive electrode terminal 20a and a negative electrode terminal 20b. The terminals 19b and 20b are connected to a common ground. As a result, the reference potentials of the primary side conversion circuits 11 to 14 become common potentials, and the reference potentials of the input ports 19 and 20 also become common potentials.

A pair of power supply lines (a positive side line and a negative side line) connected to the input port 19 are branched at the input side of the primary side conversion circuits 11 and 12, and each branched line is connected to the primary side conversion circuit 11. Each is connected to the primary side conversion circuit 12. The pair of power supply lines connected to the input port 20 are also branched and similarly connected to the primary side conversion circuits 13 and 14.

The smoothing capacitors 21 and 22 smooth the voltage input from the power sources 1 and 2. The smoothing capacitor 21 is connected to the power supply 1 in parallel, and the smoothing capacitor 22 is connected to the power supply 2 in parallel.

The circuit configuration on the secondary side will be described. The secondary side circuit 30 includes secondary windings 31 to 34, rectifiers 35 to 38, LC filters 39 to 42, bypass circuits 43 to 46, output ports 47 to 50, and a current cutoff element 71. In the secondary circuit 30, the rectifier 35 and the LC filter 39 correspond to the secondary conversion circuit 61, the rectifier 36 and the LC filter 40 correspond to the secondary conversion circuit 62, and the rectifier 37 and the LC filter 41. Corresponds to the secondary side conversion circuit 63, and the rectifier 38 and the LC filter 42 correspond to the secondary side conversion circuit 64. The secondary side conversion circuit 61 corresponds to the primary side conversion circuit 11, the secondary side conversion circuit 62 corresponds to the primary side conversion circuit 12, and the secondary side conversion circuit 63 corresponds to the primary side. The conversion circuit 13 corresponds, and the secondary conversion circuit 64 corresponds to the primary conversion circuit 14.

The secondary windings 31 to 34 are coils on the secondary side of the transformer. The secondary winding 31 is magnetically coupled to the primary winding 15. The winding ratio of the secondary windings 31 to 34 is higher than that of the primary windings 15 to 18. The secondary winding 31 is formed of a circuit in which two windings 31a and 31b are connected in series. One end of the winding 31a and one end of the winding 31b are connected to the anodes of the diodes included in the rectifier 35, respectively. The other ends of the winding 31a and the winding 31b are connected to each other, and the connection point between the other ends is connected to the negative side of the LC filter 39.

The secondary winding 32 is magnetically coupled to the primary winding 16, the secondary winding 33 is magnetically coupled to the primary winding 17, and the secondary winding 34 is magnetically coupled to the primary winding 18. Are bound to. The secondary winding 32 has two windings 32a and 32b, the secondary winding 33 has two windings 33a and 33b, and the secondary winding 34 has two windings 34a and 34b.

The rectifier 35 is a circuit that rectifies an AC voltage excited by the secondary winding 31 into a DC voltage, and is composed of a diode bridge. The rectifier 35 is a center tap type diode rectifier. The rectifier 35 is connected between the secondary winding 31 and the LC filter 39. The rectifier 36 rectifies the AC voltage excited by the secondary winding 32, the rectifier 37 rectifies the AC voltage excited by the secondary winding 33, and the rectifier 38 the AC voltage excited by the secondary winding 34. Rectify. Like the rectifier 35, the rectifiers 36 to 38 are diode bridges. The circuit configuration of the rectifiers 36 to 38 may be a diode full bridge or a current doubler type, and a motive commutation switch may be provided in parallel with the diode.

The LC filter 39 is a filter circuit in which a coil 39a and a capacitor 39b are connected. The coil 39a is connected in series to the line on the positive electrode side. The capacitor 39b is connected between a pair of power supply lines connected to the terminals 47a and 47b. The LC filter 39 is connected between the rectifier 35 and the bypass circuit 43. The LC filter 40 has a coil 40a and a capacitor 40b, the LC filter 41 has a coil 41a and a capacitor 41b, and the LC filter 42 has a coil 42a and a capacitor 42b. The circuit configuration of the LC filters 40 to 42 is the same as that of the LC filter 41.

The bypass circuit 43 bypasses between the terminal 47a and the terminal 47b. The bypass circuit 43 is composed of a relay switch. The bypass circuit 43 may be a bidirectional switch using a semiconductor element. The bypass circuit 43 is connected in parallel with the capacitor 39b and is connected between the LC filter 39 and the output port 47. When the relay switch is turned off, the bypass circuit 43 is cut off. Since the bypass circuit 43 bypasses both ends of the secondary winding 31 via the secondary side conversion circuit 61, when the bypass circuit 43 is in the cutoff state, it is converted by the secondary side conversion circuit 61. Output voltage is output from the output port 47. That is, when the bypass circuit 43 is in the cutoff state, the output from the output port 47 becomes the electric power that contributes to the electric power of the power supply 1. On the other hand, when the relay switch is turned on and the bypass circuit 43 is turned on, the voltage converted by the secondary side conversion circuit 61 is not output from the output port 47.

The bypass circuit 44 bypasses between the terminal 48a and the terminal 48b. The bypass circuit 45 bypasses between the terminals 49a and 49b. The bypass circuit 46 bypasses between the terminal 50a and the terminal 50b. Each circuit configuration and each circuit operation of the bypass circuits 44 to 46 is similar to that of the bypass circuit 43.

Circuit configuration for connecting the secondary winding 32, the secondary conversion circuit 62, the bypass circuit 44, and the output port 48, and connecting the secondary winding 33, the secondary conversion circuit 63, the bypass circuit 45, and the output port 49. The circuit configuration for connecting the secondary winding 34, the secondary side conversion circuit 64, the bypass circuit 46, and the output port 50 is the secondary winding 31, the secondary side conversion circuit 61, and the bypass circuit 43. And the output port 47 are connected.

The output port 47, the output port 48, the output port 49, and the output port 40 are connected in series. The terminal 47b and the terminal 48a are connected by wiring, the terminal 48b and the terminal 49a are connected by wiring, and the terminal 49b and the terminal 50a are connected by wiring. The terminal 47a is connected to the load 3 by the power line on the high potential side, and the terminal 50b is connected to the load by the power line on the low potential side. Of the terminals of the output ports 47 to 50, the terminals other than the terminals 47a and 50b are not directly connected to the load 3.

The output port 47 corresponds to the secondary winding 31, the bypass circuit 43, and the secondary side conversion circuit 61. The output port 48 corresponds to the secondary winding 32, the bypass circuit 44 and the secondary side conversion circuit 62, and the output port 49 corresponds to the secondary winding 33, the bypass circuit 45 and the secondary side conversion circuit 63, and the output port Reference numeral 50 corresponds to the secondary winding 34, the bypass circuit 46, and the secondary side conversion circuit 64.

The current interruption element 71 is connected between the terminal 50b and the negative electrode of the load 3. The current cutoff element 71 is a switch for switching between an electric conduction state and a cutoff state between the power conversion device 200 and the load 3. The current interruption element 71 is connected to the low potential side terminal of the output ports 47 to 50, and is connected in series to the load 3.

The controller 100 controls the switching operation of each of the switching elements S _{1 to} S ₄ included in the primary side conversion circuits 11 to 14. The controller 100 switches the switches included in the bypass circuits 43 to 46 on and off, and switches the current cutoff element 71 on and off.

Here, the characteristics of the solar cells used for the power supplies 1 and 2 will be described with reference to FIG. FIG. 2 shows the voltage and current characteristics of the solar cell. The dotted line shows the characteristic of the operating point that maximizes the outputtable power. The power that can be output by the solar cell changes depending on the intensity of light that hits the solar cell, and the stronger the light, the greater the power that can be output. The outputtable current increases as the voltage of the solar cell decreases, and the outputtable current decreases as the voltage of the solar cell increases. Due to such characteristics, the solar cell has an operating point for maximizing the output power. For example, assume that the current-voltage characteristic of the solar cell becomes the characteristic shown in the graph A of FIG. 2 when the light intensity is a predetermined value. At this time, the operating point of outputting the maximum power (maximum power point) is next to the point A _m, so that the output voltage and output current of the solar cell is in an operating point A _m, changing the operating point of the power supply 1 and 2 Therefore, the output power of the power supplies 1 and 2 becomes maximum.

In the present embodiment, the primary side circuit 10 has a maximum operating point tracking function (MPPT) that sets the operating point of the power sources 1 and 2 as the maximum power point according to the current and voltage input from the power sources 1 and 2. doing. The primary side circuit 10 changes the duty ratio of the AC voltage in order to operate the power supplies 1 and 2 with MPPT. The primary side circuit 10 includes primary side conversion circuits 11 to 14 configured by full-bridge converters of the switching elements S _{1 to} S ₄ in order to change the duty ratio of the AC voltage. , The switching operations of the half-bridge switching elements S ₁ and S ₂ are deviated from the switching operations of the half-bridge switching elements S ₃ and S ₄ .

Next, the circuit operation of the power conversion device 200 including the circuit operation of the primary side conversion circuit 11 will be described. The power conversion device 200 has a DCDC converter so as to correspond to the number of output ports 47 to 50 connected in series. In the example of FIG. 1, the power conversion device 200 has four DCDC converters. FIG. 3 shows the circuit configuration of the first stage DCDC converter among the four DCDC converters. In the following description, the first-stage DCDC converter corresponds to a power conversion circuit between the input port 19 and the output port 47, and the second-stage DCDC converter includes the input port 19 and the output port 48. Corresponds to the power conversion circuit between. The third-stage DCDC converter corresponds to a power conversion circuit between the input port 20 and the output port 49, and the fourth-stage DCDC converter includes a power conversion circuit between the input port 20 and the output port 50. Equivalent to.

FIG. 4 is a graph showing current-voltage characteristics in the circuit of FIG. In FIG. 4, the vertical axis (V, I) represents the magnitude of voltage and current, and the horizontal axis (t) represents time. Note that the circuit operation of the DCDC converters from the second stage to the fourth stage is the same as the circuit operation of the DCDC converter of the first stage described below, so description thereof will be omitted.

The input current and the input voltage input from the power supply 1 to the primary side conversion circuit 11 are I _in and V _in , respectively. When light having a constant intensity is applied to the power supply 1, the input current I _in and the input voltage V _in become the voltage and current at the operating point near the outputtable power by the circuit operation of the primary side conversion circuit 11. Transition to.

The controller 100 sets the input current I _in and the input voltage V _in to the current and voltage corresponding to the operating point so that the switching signal Sw ₁ of the Harbridge of the switching elements S ₁ and S ₂ and the switching element S ₃ , The switching signal Sw ₂ of the Harbridge of S ₄ is generated. The switching signal Sw ₁ is a signal for generating an AC voltage having a square waveform in _one half bridge (a bridge of the switching elements S ₁ and S ₂ ). In addition, the switching signal Sw ₂ is a signal for generating an AC voltage having a square waveform by the other half bridge (Herbridge of the switching elements S ₃ and S ₄ ).

In FIG. 4, V _x1 indicates the voltage input to the primary winding 15 (the output voltage of the primary conversion circuit 11), and I _x1 indicates the current input to the primary winding 15 (the primary conversion circuit 11). 11 output current). In the graph showing the voltage (V _x1 ), the square wave on the positive side represents the output voltage of the Herbridge of the switching elements S ₁ and S ₂ , and the square wave on the negative side is the switching elements S ₃ and S 2. ₄ shows the output voltage of the Harbridge.

The input voltage V _in depends on the phase difference (corresponding to the “phase shift amount” shown in FIG. 4) between the switching signal Sw ₁ and the switching signal Sw ₂ . When the condition of the light striking the battery 1 changes, the operating point changes, so that the input power that is the product of the input voltage (V _x1 ) and the input current (I _x1 ) changes. The controller 100 calculates the phase difference so that the operating point of the power supply 1 follows the maximum power point, and generates the switching signals Sw ₁ and Sw ₂ according to the phase difference. For example, in the case of increasing the input voltage (V _x1 ), the phase difference is increased to shorten the time when the switching signals Sw ₁ -Sw ₂ become zero. As a result, the controller 100 causes the output voltage (AC voltage) of the switching elements S ₁ and S ₂ and the output voltage of the switching elements S ₃ and S ₄ so that the power supply 1 operates at the operating point. By adjusting the phase difference with the AC voltage), control (hereinafter, also referred to as MPPT control) in which the output power of the power supply 1 is the outputtable power of the power supply 1 is executed.

When the primary side conversion circuit 11 operates with a phase difference between the switching signal Sw ₁ and the switching signal Sw ₂ , the output voltage of the Harbridge of the switching elements S ₁ and S ₂ and the switching elements S ₃ and S ₄ The output voltage of the Harbridge is an AC voltage having a phase difference and is applied to the primary winding 15. The voltage waveform applied to the primary winding 15 is a waveform in which the output voltages of the respective bridges are combined, and is an AC voltage (V _x1 ) as shown in FIG.

When the output voltage of the primary side conversion circuit 11 is applied to the primary winding 15, the leakage inductance connected to the primary winding 15 and the input voltage to the primary winding 15 cause the primary winding 15 to The current (I _x1 ) rises. The leakage inductance corresponds to the inductance equivalently connected in series with the primary winding 15. The leakage inductance is not shown in FIG.

The current (I _x1 ) of the primary winding 15 increases due to the leakage inductance and the input voltage (V _x1 ) during the period from time t ₁ to time t ₂ . When the current (I _x1 ) flows through the primary winding 15, an induced current flows through the secondary winding 31, which is the secondary side of the transformer. The magnitude of the induced current is determined by the magnitude of the current (I _x1 ) and the transformation ratio (1:n) of the transformer.

At time _{t 2,} when the primary winding 15 of the current _{(I x1)} to the corresponding secondary winding 31 of the current _{(I x2)} reaches the current flowing through the coil 39а _{(I rec),} 1 primary winding The amount of change in the current (I _x1 ) becomes smaller. In FIG. 4, the amount of change in the current (I _x1 ) is represented by the slope of the graph indicated by I _x1 . When the current flows through the secondary winding 31, the current flows through the coil 39 a of the LC filter 39 while flowing through the rectifier 35. The coil 39a of the LC filter 39 is excited by the difference between the output voltage (V _rec ) of the rectifier 35 and the output voltage (V _out ) of the LC filter 39. The current (I _rec ) in the coil 39a increases due to the excitation of the coil 39a during the period from time t ₂ to time t ₃ . Variation of the current from the time _{t 2} to time _{t 3} is divided by equation voltage _{(V rec)} and voltage _{(V out)} and a difference of coil 39 inductance _{(L rec) ((V rec} -V out )/L _rec ). The period during which the coil 39а is excited (excited Time: from time _{t 2} to time _{t 3} in FIG. 4), a period in which the rectifier 35 is outputting a voltage _{(V rec).}

The circuit from the output of the rectifier 35 to the output port 47 operates similarly to the step-down converter. During the excitation time, the current (I _rec ) of the rectifier 35 flows through the coil 39a, the capacitor 39b is charged, and the output current (I _out ) flows. The period after the excitation time (from time t ₃ in FIG. 4 to time t _4), the magnetic energy stored by the excitation of the coil 39а may be discharged to the output side of the LC filter 39, the output current ( I _out ) flows. As a result, the secondary side conversion circuit 61 outputs the current (I _out ) shown in FIG. The magnitude of the output voltage ( _Vout ) of the secondary side conversion circuit 61 is proportional to the length of the excitation time, and the longer the excitation time, the higher the output voltage ( _Vout ).

The phase difference, the excitation time, the output of the rectifier 35 (V _ref , I _ref ) and the output voltage of the secondary side conversion circuit 61 (V _out ) will be described with reference to FIG. FIG. 5 is a graph showing the characteristics of the output (V _ref , I _ref ) of the rectifier 35. The controller 100 calculates the phase difference (ΔP ₁ ) of the switching signals of each half bridge in order to control the power supply 1 at a predetermined operating point, and based on the calculated phase difference (ΔP ₁ ) the primary side conversion circuit. 11 is operated.

The output port 47, the output port 48, the output port 49, and the output port 50 are connected in series. The terminal 47b and the terminal 48a are connected by wiring, the terminal 48b and the terminal 49a are connected by wiring, and the terminal 49b and the terminal 50a are connected by wiring. The terminal 47a is connected to the load 3 by the power line on the high potential side, and the terminal 50b is connected to the load by the power line on the low potential side. Of the terminals of the output ports 47 to 50, the terminals other than the terminals 47a and 50b are not directly connected to the load 3.

As a result, in the present embodiment, the controller 100 executes the MPPT control by controlling the phase difference (phase shift amount) so that the power that can be output from the power supply 1 becomes the power corresponding to the operating point.

Next, the output voltage assigned to the secondary side conversion circuits 61 to 64 when the voltage is output to the load 3 will be described with reference to FIGS. 1 and 3.

As shown in FIG. 1, the input side of the power conversion device 200 is connected to power sources 1 and 2 independent of each other via input ports 19 and 20, respectively. The operating points of the power sources 1 and 2 may differ depending on how the light hits. Therefore, the current supplied from the primary side to the secondary side is different for each DCDC converter included in the power conversion device 200.

At the output of the power conversion device 200, the output ports 47 to 50 are connected in series. The output voltage of the secondary side circuit 30 becomes the total voltage of the output voltages of the secondary side conversion circuits 61 to 64, and the output current of the secondary side circuit 30 is common to the output currents of the secondary side conversion circuits 61 to 64. To do. Therefore, in order to maintain the output voltage of the secondary circuit 30 when the output voltage of the secondary conversion circuit 61 of the first stage drops, for example, the secondary conversion of the second to fourth stages is required. The output voltage of circuits 62-64 must be increased.

In the secondary conversion circuit 61 of the first stage, the case where the output voltage (V _ref ) of the rectifier 35 is larger than the output voltage (V _out ) of the LC filter 39 is given as an example, and then the secondary conversion circuit 61. The output balance of .about.64 will be described. Unlike the present embodiment, if the secondary conversion circuit 61 of the first stage is an independent converter without depending on the outputs of the other secondary conversion circuits 62 to 64, the output voltage of the rectifier 35 ( The output current (I _out ) of the LC filter 39 increases as V _ref ) increases. In the present embodiment, the output current of the secondary conversion circuit 61 of the first stage is common to the output current of the secondary conversion circuits 62 to 64 of the second to fourth stages. Therefore, if the output currents of the secondary conversion circuits 62 to 64 of the second to fourth stages cannot follow the output current of the secondary conversion circuit 61 of the first stage, the secondary conversion of the first stage is performed. The output voltage (V _out ) of the circuit 61 increases.

In the secondary conversion circuit 61 of the first stage, the output current (I _ref ) of the rectifier 35 changes by (V _rec −V _out )/L _{rec as} described above, and thus the excitation voltage of the coil 39 a of the LC filter 39. Depends on The excitation voltage is the difference between the output voltage (V _rec ) of the rectifier 35 and the output voltage (V _out ) of the LC filter 39. That is, when the output voltage ( _Vout ) increases, the excitation voltage ( _Vrec - _Vout ) decreases, so the output current ( _Iout ) of the first-stage secondary side conversion circuit 61 decreases. As a result, the output currents of the secondary side conversion circuits 62 to 64 of the second stage to the fourth stage can follow the output current of the secondary side conversion circuit 61 of the first stage. As a result, when the controller 100 performs the MPPT control, the output voltage is assigned to the secondary side conversion circuits 61 to 64 as an appropriate output voltage according to the states of the power supplies 1 and 2.

In the above circuit operation, the output current of the secondary conversion circuit 61 of the first stage increases, and thus the output currents of the secondary conversion circuits 62 to 64 of the second to fourth stages become insufficient. In this case, the capacitors 40b, 41b, 42b connected to the output sides of the secondary side conversion circuits 62 to 64 are discharged to compensate for the insufficient current, and the outputs of the secondary side conversion circuits 62 to 64 are supplemented. The current may follow the output current of the first-stage secondary side conversion circuit 61. In such a case, when the output voltages of the secondary side conversion circuits 62 to 64 decrease due to the discharge of the capacitors 40b, 41b and 42b, the excitation voltage (V _rec − of the coils 40a, 41a and 42a of the LC filters 40 to 42). Since V _out ) increases, the output current (I _rex ) of the rectifier 35 increases. Therefore, in the output voltage (V _out ) of the secondary side conversion circuits 62 to 64, the voltage drop due to the discharge of the capacitors 40b, 41b, and 42b is suppressed, and the output voltage (V _out ) of the secondary side conversion circuits 62 to 64 is reduced. growing. As a result, in the present embodiment, the output voltage (V _rec ) of the rectifiers 35 to 36, the coils 39a and 40a, while suppressing the decrease in the output current (I _out ) due to the discharge of the capacitors 39b, 40b, 41b, and 42b, The voltage balance between the excitation voltage (V _rec −V _out ) of 41 a and 42 a and the output voltage (V _out ) of the secondary side conversion circuits 61 to 64 can be maintained. At this time, the control of the DCDC converter by the controller 100 is only MPPT control for the primary side circuit 10, and does not include control for the secondary side circuit 20. That is, if the controller 100 performs MPPT control, various voltages and currents in the secondary circuits 61 to 64 are balanced.

In the secondary conversion circuit 61 of the first stage, the case where the output voltage (V _ref ) of the rectifier 35 is smaller than the output voltage (V _out ) of the LC filter 39 is given as an example, and then the secondary conversion circuit 61. The output balance of .about.64 will be described. When the input voltage (V _ref ) of the LC filter 39 is smaller than the output voltage (V _out ), the current supplied from the primary winding 15 to the secondary winding 31 does not flow. On the other hand, since the output currents of the secondary side conversion circuits 61 to 64 are common currents, the capacitor 39b included in the secondary side conversion circuit 61 discharges and outputs a current. When the capacitor 39b is discharged, the output voltage (V _out ) of the secondary side conversion circuit 61 becomes low. When the output voltage (V _ref ) becomes larger than the output voltage (V _out ), the coil 39a of the LC filter 39 is ready to be excited, so that the current can be supplied from the primary winding 15 to the secondary winding 31. Become. Therefore, the primary side conversion circuit 61 can operate under the MPPT control, and the power supply 1 can operate at the operating point.

As described above, when the outputtable power of the power supplies 1 and 2 on the input side of the primary side circuit 10 is small, the outputs of the secondary side conversion circuits 61 to 64 corresponding to the power supplies 1 and 2 having a small outputtable power. The voltage drops. Further, when the outputtable power of the power supplies 1 and 2 on the input side of the primary side circuit 10 is large, the output voltages of the secondary side conversion circuits 61 to 64 corresponding to the power supplies 1 and 2 having the large outputtable power rise. To do. Further, when the controller 100 performs MPPT control, the output voltage is assigned to the secondary side conversion circuits 61 to 64 as an appropriate output voltage according to the states of the power supplies 1 and 2.

Next, switching control of the operation circuit by the controller 100 and switching control of the conduction circuit by the controller 100 will be described. The controller 100 switches between a circuit that operates and a circuit that does not operate among the plurality of primary side conversion circuits 11 to 14 according to the step-up ratio of the power conversion circuit. In addition, the controller 100 switches between a circuit that conducts and a circuit that shuts off among the plurality of bypass circuits 43 to 46 according to the boosting ratio of the power conversion circuit.

The power conversion device 200 controls the supply of the voltage from the primary side to the secondary side by switching the operation circuit among the plurality of primary side conversion circuits 11 to 14. For example, of the two primary side conversion circuits 11 and 12 connected to the power source 1, the primary side conversion circuit 11 is operated and the primary side conversion circuit 12 is controlled not to operate. Specifically, the controller 100 performs the switching operation of the switching elements S _{1 to} S ₄ included in the primary side conversion circuit 11 to turn off the switching elements S _{1 to} S ₄ included in the primary side conversion circuit 12. Maintain at. Since the primary side conversion circuit 11 operates as an operation circuit, the output voltage of the power supply 1 is boosted via the DCDC converter of the first stage. On the other hand, since the primary side conversion circuit 12 does not operate as an operation circuit, the output voltage of the power supply 1 is not boosted via the second stage DCDC converter. Since the second-stage DCDC converter is stopped, the overall boost ratio is smaller than the overall boost ratio when the first-stage DCDC converter and the second-stage DCDC converter are operated. The overall boosting ratio when boosting the power supply 1 corresponds to the ratio between the output voltage of the power supply 1 and the output voltage between the terminals 47a and 48b. The controller 100 switches the operation circuits of the plurality of secondary side conversion circuits 13 and 14 also in the third-stage DCDC converter and the fourth-stage DCDC converter connected to the power supply 2 according to the overall boost ratio.

Further, the bypass circuits 43 to 46 connected in correspondence with the primary side conversion circuits 11 to 14 to be operated are in the cutoff state. The bypass circuits 43 to 46 connected in correspondence with the primary side conversion circuits 11 to 14 which are not operated are brought into a conductive state. The controller 100 turns off the switches included in the bypass circuits 43 to 46 to turn off the bypass circuits 43 to 46. Further, the controller 100 turns on the switches included in the bypass circuits 43 to 46 to bring the bypass circuits 43 to 46 into a conductive state. When the bypass circuits 43 to 46 are in the cutoff state, the output ports 47 to 50 output the voltage boosted by the DCDC converter. On the other hand, when the bypass circuits 43 to 46 are conductive, the terminals of the output ports 47 to 50 are short-circuited.

In the present embodiment, in order for the power converter 200 to output a voltage to the load 3, the output voltage of the secondary circuit 30 must be higher than the voltage of the load 3. When the outputtable power of the power supplies 1 and 2 is low, the output voltage of the power supplies 1 and 2 is low, and in order to increase the output voltage of the secondary side circuit 30, the step-up ratio of the DCDC converter must be increased.

In the present embodiment, the output ports 47 to 50 are connected in series, and the outputs of the plurality of DCDC converters are connected to the output ports 47 to 50. In order to increase the overall boosting ratio of the power conversion device 200 and increase the output voltage of the secondary circuit 30, the voltages of the power supplies 1 and 2 are boosted by a plurality of DCDC converters, and the boosted voltage is increased to 2 The output signals may be output from the secondary conversion circuits 61 to 64, respectively. On the other hand, when the boosting ratio of the entire power converter 200 may be low, the voltages of the power supplies 1 and 2 may not be boosted by the plurality of DCDC converters.

As a characteristic of the DCDC converter, the efficiency of the power conversion device 200 decreases as the boost ratio increases. Therefore, when operating the primary side conversion circuits 11 to 14, the output voltage of the secondary side circuit 30 can be higher than the voltage of the load 3 while avoiding the operation of the DCDC converter in a state where the boost ratio is high. Good.

When the power that can be output from the power source 1 is high, the overall boost ratio of the DCDC converter may be low, so the controller 100 operates either the primary side conversion circuit 11 or the primary side conversion circuit 12. It operates, and the other circuit does not operate. Further, the controller 100 turns off the bypass circuits 43 and 44 corresponding to the operated primary side conversion circuits 11 and 12, and turns on the bypass circuits 43 and 44 corresponding to the non-operated primary side conversion circuits 11 and 12. And

When the power that can be output from the power supply 1 is low, the controller 100 operates both the primary-side conversion circuit 11 and the primary-side conversion circuit 12 in order to increase the boost ratio of the entire DCDC converter. Further, the controller 100 turns off the bypass circuits 43 and 44 corresponding to the operated primary side conversion circuits 11 and 12.

Since the operating point of the power source 1 and the operating point of the power source 2 are different, the controller 100 switches the operating circuits of the primary side conversion circuits 11 and 12 according to the outputtable power of the power source 1 and the primary side conversion circuit. The switching of the operation circuits 13 and 14 is controlled respectively.

6 is a circuit diagram of the power conversion system shown in FIG. 1, in which the current-voltage characteristics of the power supplies 1 and 2, the output voltage (V _rec ) characteristics of the rectifiers 35 to 38, and the output current of the secondary side conversion circuit ( _Iout ) characteristic graph is added. V _in1 and I _in1 represent an input voltage and an input current input from the power supply 1 , and V _in2 and I _in2 represent an input voltage and an input current input from the power supply 2 . Note that, in FIG. 6, the circuit surrounded by the alternate long and short dash line shows a circuit that is not operating among the primary side conversion circuits 11 to 14. In the example of FIG. 6, the primary side conversion circuit 12 is not operating. Note that the controller 100 is not shown in FIG.

For example, when the outputtable power of the power supply 1 is low and the outputtable power of the power supply 2 is high, the controller 100 operates the primary-side conversion circuit 11 and does not operate the primary-side conversion circuit 12, and The side conversion circuit 13 and the primary side conversion circuit 14 are operated. That is, when the step-up ratio may be low, the loss can be suppressed by stopping the operation of the second-stage DCDC converter among the first-stage and second-stage DCDC converters. When a high step-up ratio is required, the DCDC converters in the third and fourth stages are operated to increase the output voltage. As a result, the overall boost ratio can be increased while suppressing the loss.

The controller 100 switches the operation circuits of the primary side conversion circuits 11 to 14 as described above according to each step-up ratio required for the plurality of DCDC converters. The controller 100 calculates the outputtable voltage corresponding to the operating points of the power supplies 1 and 2. The controller 100 calculates the overall boosting ratio from the output voltage required for the load and the calculated outputtable voltage. The controller 100 sets the first step-up ratio to the output voltage of the power source 1 according to the overall step-up ratio and the losses of the plurality of DCDC converters so that the output voltage of the secondary side circuit 30 becomes higher than the voltage of the load, and , A second step-up ratio for the output voltage of the power supply 2 is calculated. The controller 100 compares the first boost ratio with a predetermined threshold value, and compares the second boost ratio with a predetermined threshold value. The predetermined threshold is a threshold determined according to the loss of the DCDC converter, and represents how many converters among the converters connected to the power sources 1 and 2 operate to improve efficiency. .. Then, when the first boost ratio is higher than the predetermined threshold value, the controller 100 selects either one of the primary side conversion circuit 11 and the primary side conversion circuit 12 as the operation circuit, and the other one. Do not select the conversion circuit as the operation circuit. On the other hand, when the first boost ratio is less than or equal to the predetermined threshold value, the controller 100 selects both the primary side conversion circuit 11 and the primary side conversion circuit 12 as operation circuits. Regarding the primary side conversion circuits 13 and 14, the controller also selects a conversion circuit to be operated and a conversion circuit to not be operated according to the comparison result of the second boost ratio and the predetermined threshold value. Further, the controller 100 puts the bypass circuits 43 to 46 corresponding to the operated primary side conversion circuits 11 to 14 into the cutoff state, and brings the bypass circuits 43 to 46 corresponding to the unoperated primary side conversion circuits 11 to 14 into conduction. State. As a result, the overall boost ratio can be increased while suppressing the loss of the power conversion device 200.

When the outputtable power of the power supplies 1 and 2 is high and the voltage of the load 3 is low and the voltage difference between the input and output of the DCDC converter is large, the step-down ratio of the DCDCDC converter becomes high. As the step-down ratio becomes higher, the phase shift amount (duty ratio of the switching signal) becomes lower and the current flowing through the full bridge becomes larger. Therefore, the efficiency of the power conversion device 200 is reduced. In this embodiment, even when the step-down operation of the DCDCDC converter is performed, the controller 100 operates the circuits in the primary side conversion circuits 11 to 14 so as to reduce the overall loss, similarly to the above. While switching, the bypass circuits 43 to 47 are switched on and off. In other words, the controller controls the number of DCDC converters to operate and the number of DCDC converters to stop among the four-stage DCDC converters. Accordingly, even when the DCDC converter is stepped down, the amount of current flowing back through the full bridge can be suppressed and the loss can be suppressed. That is, the present embodiment can widen the voltage range of the output voltage with respect to the input voltage while suppressing the loss of the power conversion device 200.

Next, the control of the current interruption element 71 will be described. When the total value of the power that can be output from the power sources 1 and 2 is smaller than the total power consumption of the power conversion device, the controller 100 turns off the current interruption element 71. In addition, the controller 100 stops the switching operation of the switching elements S _{1 to} S ₄ included in the primary side conversion circuits 11 to 14 while turning off the current cut-off element 71, so that the primary side changes to the secondary side. Ban power supply.

Further, the total value of the power that can be output from the power sources 1 and 2 is larger than the total power consumption of the power conversion device, and the output voltage of the secondary circuit 30 is higher than the voltage of the load 3 based on the power of the power sources 1 and 2. When it is low, the controller 100 may charge the capacitors 39b, 40b, 41b, 42b by the following control. The controller 100 turns off the current interruption element 71 and performs the switching operation of the switching elements S _{1 to} S ₄ included in the primary side conversion circuits 11 to 14.

As described above, in the present embodiment, the power conversion device 200 corresponds to the primary side circuit having the input ports 19 and 20, the plurality of output ports 47 to 50, and the plurality of output ports 47 to 50. And a secondary side circuit having a plurality of connected secondary side conversion circuits 61 to 64. The primary side circuit 10 and the secondary side circuit 30 are insulated from each other. The primary-side circuit 10 controls the operating point of the power sources according to the input currents input from the power sources 1 and 2 and the input voltage input from the power sources 1 and 2 to reduce the input power of the power sources 1 and 2. increase. The plurality of output ports 47 to 50 are connected in series. When the power supplies 1 and 2 operate at a predetermined operating point, the input power of the power supplies 1 and 2 is output to the plurality of secondary side conversion circuits 61 to 64, respectively. Thereby, power conversion can be performed while suppressing loss. Further, the boosting ratio can be increased while increasing the power of the power supplies 1 and 2 connected to the input ports 19 and 20.

By the way, the system according to the present embodiment is applied to a system that supplies a load of electric power of a power source whose outputtable power fluctuates, such as a solar cell power generation system. In such a system, the power supply voltage is boosted and supplied to the load voltage, but if the boosting ratio becomes high, the efficiency of the power conversion device deteriorates.

Therefore, as a method of suppressing the step-up ratio of the converter, a method of connecting a plurality of power sources in series and connecting the plurality of power sources to a power conversion device having a low step-up ratio can be considered. For example, in a solar power generation system for home use, many solar power generation cells are connected in series.

However, when a plurality of power supplies are connected in series, the currents of all the power supplies are common. For example, in the case of a photovoltaic power generation system, if a part of the photovoltaic cells connected in series is shaded and the current that can be supplied to the shaded cells drops, the other cells have power supply capability. Even so, since the power supplies are connected in series, other cells can only flow the current of the shaded cells, which causes a problem that the energy that can be output is significantly reduced.

As a method for solving such a problem, for example, in Japanese Patent Laid-Open No. 2011-522313, the power conversion circuits are dispersed to reduce the number of power supplies connected in series. A system is known in which power generation is controlled by maximizing the generated power of a power supply group connected to each power conversion circuit, and the outputs are connected in series to obtain a high boost ratio while increasing the generated power energy. ing. However, since the power conversion circuits connected in series are non-insulating types, there is a problem that not only a power supply that generates a plurality of circuit potentials is required but also the reference voltage of the power supply group becomes high. In addition, there is a problem that control becomes complicated.

In this embodiment, since the primary side circuit and the secondary side circuit are insulated from each other, it is possible to realize a low reference potential while suppressing the number of reference potentials in the primary side operation circuit. Further, the circuit configurations of the plurality of DCDC converters are simple, and the entire DCDC converter can be controlled by controlling the conversion circuit on the primary side.

Moreover, in this embodiment, the output ports 47-50 have a pair of terminals 47a-50a, 47b-50b, and connect the capacitors 39b-42b to a pair of terminals 47a-50a, 47b-50b. This allows the power conversion device 200 to maintain a constant output when the outputs of the power supplies 1 and 2 drop for a short time.

In addition, in the present embodiment, the secondary circuit 30 has bypass circuits 43 to 46 that bypass between the pair of terminals 47a to 50a and 47b to 50b. As a result, when the input power from one of the power supplies 1 and 2 is small, the number of circuit elements through which current flows can be reduced by short-circuiting the output ports 47 to 50. As a result, the resistance loss in the DCDC converter is reduced, and the efficiency can be improved.

In addition, in the present embodiment, the controller 100 switches a circuit that conducts as a conduction circuit among the plurality of bypass circuits 43 to 46 according to the boost ratio. With this, it is possible to adjust the boost ratio suitable for the power supply voltage and the load voltage, and it is possible to widen the output range of the power conversion circuit.

In addition, in the present embodiment, the controller 100 switches the conduction circuits of the bypass circuits 43 to 46 according to the maximum input power input from the power sources 1 and 2. As a result, it is possible to adjust to a boost ratio suitable for the power that can be output by the power supplies 1 and 2, and it is possible to widen the output range of the power conversion circuit.

Further, in the present embodiment, the controller 100 switches the conduction circuits of the bypass circuits 43 to 46 so that the voltage output from the plurality of output ports 47 to 50 to the load 3 becomes higher than the output voltage of the load 3. As a result, it is possible to adjust the boost ratio suitable for the load voltage, and it is possible to widen the output range of the power conversion circuit.

Further, in the present embodiment, the primary side circuit 10 has primary windings 15 to 18, the secondary side circuit 30 has a plurality of secondary windings 31 to 34, and a plurality of secondary windings 31. To 34 are connected corresponding to the plurality of secondary side conversion circuits 61 to 64, and the plurality of bypass circuits 43 to 46 are switches connected between terminals at both ends of the secondary windings 31 to 34. Of the plurality of bypass circuits, the controller 100 turns on the switches included in the conduction circuit and turns off the switches not included in the conduction circuit among the plurality of bypass circuits. Thereby, the setting range of the boost ratio can be expanded while suppressing the loss. Further, since the output of the DCDC converter can be switched with a small number of switches, the circuit can be downsized.

Further, in the present embodiment, the primary side circuit 10 has a plurality of primary side conversion circuits 11 to 14 connected in parallel to the power sources 1 and 2. The controller 100 switches the circuit operating as an operation circuit among the plurality of primary side conversion circuits 11 to 14 according to the boost ratio. Thereby, the setting range of the boost ratio can be expanded while suppressing the loss. Further, since the DCDC converter to be operated can be switched only by controlling the primary side circuit, control can be facilitated.

Further, in the present embodiment, the controller 100 includes circuits for operating the primary side conversion circuits 11 to 14 so that the voltage output from the plurality of output ports 47 to 50 to the load 3 becomes higher than the output voltage of the load 3. Switch. As a result, it is possible to adjust the boost ratio suitable for the load voltage, and it is possible to widen the output range of the power conversion device 200.

Further, in the present embodiment, the circuits for operating the primary side conversion circuits 11 to 14 are switched according to the maximum input power input from the power sources 1 and 2. This makes it possible to adjust to a boost ratio suitable for the power that can be output by the power supplies 1 and 2, and the output range of the power conversion device 200 can be expanded.

In the present embodiment, the controller 100 includes a plurality of switching elements _S 1 to S ₄ included in the serial plurality of primary conversion circuit 11 to 14, the switching of the switching elements _S 1 to S ₄ included in the operation circuit The operation is performed and the switching elements S _{1 to} S ₄ not including the operation circuit are turned off. Thereby, the setting range of the boost ratio can be expanded while suppressing the loss. Further, since the operation circuit can be switched by the control signal which is normally used, the control signal line can be reduced.

Further, in the present embodiment, the primary side conversion circuits 11 to 14 output the first AC voltage to the first output terminal (corresponding to the connection point between the switching element S ₁ and the switching element S ₂ ) and the second AC voltage. It has a second output terminal (corresponding to a connection point between the switching element S ₃ and the switching element S ₄ ) for outputting, converts the input voltage of the power sources 1 and 2 into a first AC voltage, and inputs the power sources 1 and 2. Voltage is converted into a second AC voltage, and the first output terminal and the second output terminal are connected to the same primary windings 15, 16, 17, and 18, and the phase of the first AC voltage and the second AC voltage Are out of phase. As a result, the voltage applied to the transformer is not biased, and the heat generation of the transformer can be suppressed. As a result, the transformer can be downsized.

Further, in the present embodiment, the controller 100 adjusts the phase difference between the first AC voltage and the second AC voltage so that the operating points of the power sources 1 and 2 become the maximum input power input from the power sources 1 and 2. Control. As a result, since the input power of the power supplies 1 and 2 can be maximized by controlling only the phase difference, the calculation load on the controller 100 can be reduced.

Further, in the present embodiment, the plurality of input ports 19 and 20 included in the primary side circuit 10 are respectively connected to the plurality of power sources 1 and 2, and the reference potentials of the plurality of input ports 19 and 20 are connected. Is a common potential. As a result, since the power supply potentials of the primary side conversion circuits 11 to 14 which are the operation circuits can be made common, the primary side conversion circuits 11 to 14 can be downsized.

Further, in the present embodiment, the controller 100 prohibits the power supply from the primary side circuit 10 to the secondary side circuit 30 when the outputtable power of the power sources 1 and 2 is lower than the operating power of the primary side circuit 10. To do. As a result, the overall efficiency of the system including the power conversion device 200 can be improved.

In addition, in the present embodiment, the secondary circuit 30 is composed of a rectifying element and a passive element. As a result, the secondary side does not need to be configured by the operation circuit, and thus the circuit can be downsized.

Further, in the present embodiment, the power conversion device includes a current interruption element 71 that interrupts the current flowing from the plurality of output ports 47 to 50 to the load 3, and the current interruption element 71 is connected to the plurality of output ports 47 to 50 in series. Has been done. As a result, the power transmission to the load 3 can be stopped by switching one switch on and off, which improves maintainability.

When the voltage output from the plurality of output ports 47 to 50 to the load 3 is lower than the output voltage of the load 3, the current cutoff element 71 is turned off. Thereby, when the output voltage of the power converter becomes smaller than the load voltage, it is possible to prevent the backflow of power. It is possible to prevent the voltage sharing ratio of each output port from becoming uniform.

Further, in the present embodiment, the current cutoff element 71 is connected to the output port 50 having the lowest potential among the plurality of output ports 47 to 50. Thereby, safety can be improved.

Although capacitors are connected to the output ports 47 to 50 as capacitance elements in the present embodiment, electric double layer capacitors or the like may be connected.

<<Second Embodiment>>
FIG. 7 shows a circuit diagram between the power supply 1 and the output ports 47 and 48 of the power conversion device 200 according to another embodiment of the invention. In this example, the configuration of the primary side circuit 10 is different from that of the above-described first embodiment. The configuration other than this is the same as that of the first embodiment described above, and the description thereof is incorporated.

As shown in FIG. 7, the primary winding 15 included in the primary side circuit 10 has two secondary windings 31 and 32 magnetically coupled. The winding ratio between the primary winding 15 and the secondary winding 31 is 1:n (n is an integer greater than 1), and the winding ratio between the primary winding 15 and the secondary winding 32 is 1:. n (n is an integer greater than 1). The secondary winding 31 is connected to the output port 47 via the secondary conversion circuit 61, and the secondary winding 32 is connected to the output port 47 via the secondary conversion circuit 62.

When the current flows through the primary winding 15, the induced current flows through the secondary winding 31 and the secondary winding 32, respectively. The voltage generated by the induced current flowing in the secondary winding 31 and the voltage generated by the induced current flowing in the secondary winding 32 are boosted by n times the voltage of the primary winding 15. Voltage. Then, the AC voltage of the secondary winding 31 is supplied to the secondary conversion circuit 61, and the AC voltage of the secondary winding 32 is supplied to the secondary conversion circuit 62. Then, the voltages converted by the secondary side conversion circuit 61 and the secondary side conversion circuit 62 are summed by the output ports 47 and 48 connected in series.

As a result, the input power when the power supply 1 operates at the operating point is output to the plurality of secondary side conversion circuits 61 and 62, respectively. Thereby, power conversion can be performed while suppressing loss. Further, the boosting ratio can be increased while increasing the power of the power supply 1 connected to the input port 19.

The circuit configuration shown in FIG. 7 is not limited to the DCDC converter connected to the power supply 1 and may be used for the DCDC converter connected to the power supply 2.

1, 2... Power source 3... Load 10... Primary side circuits 11-14... Primary side conversion circuits 15-18... Primary windings 19, 20... Input ports 21, 22... Smoothing circuit 30... Secondary side circuit 31 -34... Secondary windings 35-38... Rectifiers 39-42... Filters 39a, 40a, 41a, 42a... Coils 39b, 40b, 41b, 42b... Capacitors 43-46... Bypass circuits 47-50... Output ports 61-64 ... Secondary side conversion circuit 71 ... Current interruption element 100 ... Controller

Claims (19)

In the power converter that converts the input power input from the power supply and supplies the converted power to the load,
Connected to the load and the primary circuit having an input port connected to the power source, a plurality of output ports, prior Symbol plurality of secondary side that are connected corresponding to a plurality of output ports each having a pair of terminals A secondary circuit having a conversion circuit and a plurality of bypass circuits for bypassing between the pair of terminals ,
A controller for controlling the plurality of bypass circuits ,
The primary side circuit and the secondary side circuit are insulated from each other,
The primary side circuit is a circuit that increases the input power by controlling an operating point of the power supply according to an input current input from the power supply and an input voltage input from the power supply,
The plurality of output ports are connected in series,
The input power when the power supply operates at the operating point is output to each of the plurality of secondary side conversion circuits ,
The controller is a power converter that switches a circuit to be bypassed among the plurality of bypass circuits so that a loss of the power converter is low . Before SL secondary circuit, the power conversion apparatus according to claim 1 having a connected capacitive elements between the pair of terminals. Before SL controller, depending on the boosting ratio, a plurality of power converter according to claim 2, wherein switching the circuitry to conduct a conductive circuit in the bypass circuit. Before SL controller, such that the voltage output to the load from the plurality of output ports is higher than the output voltage of the load, the power converter according to claim 3, wherein switching the conduction circuit. Wherein the controller, the power converter according to claim 3 or 4, wherein switching the conducting circuits according to the maximum input power input from the power supply. The primary side circuit has a primary winding,
The secondary circuit has a plurality of secondary windings magnetically coupled to the primary winding,
The plurality of secondary windings are connected to correspond to the plurality of secondary side conversion circuits,
Each of the plurality of bypass circuits has a switch connected between terminals of both ends of the secondary winding,
The controller is
Among the plurality of bypass circuits, to the switch-on condition included in the conductive circuit, power conversion according to any one of claims 3-5 to turn off the switch that is not included in the conducting circuit apparatus. A controller for controlling the primary side circuit is provided, and the primary side circuit has a plurality of primary side conversion circuits that are connected in parallel to the power supply and supply electric power to the secondary side conversion circuit,
The plurality of primary side conversion circuits and the plurality of secondary side conversion circuits respectively correspond to each other,
The controller is
Depending on the step-up ratio, power converter according to any one of claims 1 to 6, switching circuits that operate as an operation circuit among the plurality of primary conversion circuit. The power conversion device according to claim 7 , wherein the controller switches the operation circuit so that a voltage output from the plurality of output ports to the load becomes higher than an output voltage of the load. Wherein the controller, the power converter according to claim 7 or 8, wherein switching the operation circuit according to the maximum input power input from the power supply. A controller for controlling the primary side circuit,
Each of the plurality of primary side conversion circuits has a switching element,
The controller performs a switching operation of a switching element included in the operation circuit among a plurality of switching elements included in the plurality of primary side conversion circuits, and turns off a switching element not included in the operation circuit. power converter according to any one of claims 7 to 9. The primary side circuit has a primary winding and a primary side conversion circuit,
The secondary circuit has a secondary winding magnetically coupled to the primary winding,
The primary side conversion circuit has a first output terminal that outputs a first AC voltage and a second output terminal that outputs a second AC voltage, converts the input voltage to the first AC voltage, and Convert the input voltage to the second AC voltage,
The first output terminal and the second output terminal are connected to the same primary winding,
The phase of the said 1st alternating voltage and the phase of the said 2nd alternating voltage differ, The power converter device as described in any one of Claims 1-10 . A controller for controlling the primary side circuit,
The power conversion device according to claim 11 , wherein the controller controls the phase difference between the first AC voltage and the second AC voltage so that the electric power input from the power source becomes maximum at the operating point. .. The plurality of input ports included in the primary side circuit are respectively connected to the plurality of power sources,
Wherein the plurality of reference potential at the input ports A power converter according to any one of claims 1 to 11, which is a common potential. A controller for controlling the primary side circuit,
It said controller, when the output electric power of the power supply is lower than the power consumption of the power converter, either from the primary circuit of claim 1 to 13 for inhibiting the supply of power to the secondary circuit The power converter according to claim 1. The secondary circuit includes a power converter according to any one of claims 1 to 14 configured by the rectifier element and a passive element. It said output port being connected in series, the power conversion device according to any one of the plurality of claims 1 to 15 which has a current cut-off device for interrupting the current flowing through the load from the output port. The power converter according to claim 16 , wherein the current cutoff element is turned off when the voltage output from the plurality of output ports to the load is lower than the output voltage of the load. The power converter according to claim 16 or 17 , wherein the current interruption element is connected to the output port having the lowest potential among the plurality of output ports. Power converter according to any one of claims 1 to 18, wherein the power supply is a solar cell.

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