JP2012120387A - Step up/down circuit, and power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a step up/down circuit and a power converter capable of improving power factor, with reduction in size and loss.SOLUTION: A step up/down circuit 56 steps up or down the input voltage applied from an AC power supply 201, and supplies it to a load. It includes a full wave rectification part 16 which rectifies the input voltage so that the input voltage comes to be a voltage of predetermined polarity, a winding part 11 which contains a winding L1 and a winding L2 which are magnetically connected each other, with a voltage having been rectified by the full wave rectification part 16 being applied to the winding L1, and a route switching part 12 which switches a route of the current that flows the step up/down circuit 56 for performing a step up operation in which the winding part 11 outputs a boosted voltage or a step down operation in which the winding part 11 outputs a voltage that has been stepped down. Since the route of a current is switched by the route switching part 12, the current flowing from the AC power source 201 flows the winding L1 during the step up operation and the step down operation.

Description

  The present invention relates to a step-up / down circuit and a power conversion device, and more particularly to a step-up / down circuit and a power conversion device having a power factor improving function.

  2. Description of the Related Art Power converters for charging driving main batteries such as electric vehicles (EV) and plug-in hybrid vehicles (HV) using ordinary household AC power have been developed.

  That is, one of the features of an electric vehicle and a plug-in hybrid car is that an in-vehicle battery as a main battery can be charged using an external power source such as a household outlet. And in order to charge a vehicle-mounted battery using the household outlet of AC100V or AC200V, the AC / DC converter for converting an alternating voltage (AC) into the direct current voltage (DC) for a battery is needed.

  Patent Document 1 below discloses an AC / DC converter that can increase or decrease the output DC voltage by changing the duty ratio by switching. According to the AC / DC converter, after the full-wave rectification is performed on the AC input in the step-up / step-down circuit, the release of the energy accumulated in the reactor is turned on / off by the chopper control by the switching, so that the step-up or step-down is performed. Obtain a possible DC output. Further, if the waveform of the current flowing through the reactor is controlled to be similar to the waveform of the input voltage by this on / off control, the power factor at the time of power conversion of the AC / DC converter can be improved.

Japanese Patent Laid-Open No. 10-304670

  Some of the AC / DC converters disclosed in Patent Document 1 perform voltage step-up / step-down using a step-up / down chopper type step-up / down circuit. The step-up / step-down chopper type step-up / step-down circuit switches whether or not an input voltage is applied to the reactor by switching a switching element, and accumulates magnetic energy in the reactor. Then, the boosted or stepped down voltage is output by releasing the energy accumulated in the reactor by switching the switch element.

  However, the step-up / step-down circuit using this step-up / step-down chopper method has a period in which the input current is turned off by switching of the switching element, so that it is at the same level as a step-up chopper type circuit without a period in which the input current is turned off. In order to obtain the output current, it is necessary to set a large input current. When the input current increases, the ripple current in the step-up / step-down circuit also increases, so that the loss in the circuit element increases.

  In order to cope with a large input current, a step-up / step-down chopper type step-up / step-down circuit is required to have a higher power capacity in circuit elements than a step-up chopper type circuit. Therefore, the step-up / step-down chopper type step-up / step-down circuit increases the size of the device as compared with the step-up chopper type circuit.

  Furthermore, in the buck-boost circuit of the buck-boost chopper method, there is a period in which the input current flowing through the reactor is turned off by the switch element, so that the power factor deteriorates due to the collapse of the waveform similarity between the input current and the input voltage. There are also problems.

  The present invention has been made in view of such circumstances, and an object of the present invention is to obtain a step-up / step-down circuit and a power conversion device capable of improving the power factor while reducing the size and the loss.

  The step-up / step-down circuit according to the first aspect of the present invention is a step-up / step-down circuit for stepping up or stepping down an input voltage input from a power source and supplying the input voltage to a load, wherein the input voltage is a voltage having a predetermined polarity. A rectifying unit that rectifies the first winding and a second winding that are magnetically coupled to each other, and a winding unit that applies a voltage rectified by the rectifying unit to the first winding; A path switching unit that switches a path of a current flowing through the step-up / down circuit in order to perform a step-up operation in which the winding unit outputs a boosted voltage or a step-down operation in which the winding unit outputs a step-down voltage. In the step-up operation and the step-down operation, the current flowing from the power source flows through the first winding.

  According to the step-up / step-down circuit according to the first aspect, the rectifier performs rectification so that the input voltage becomes a voltage having a predetermined polarity. The winding unit receives the voltage rectified by the first winding, and accumulates magnetic energy in the first winding and the second winding that are magnetically coupled to each other. The path switching unit switches the current path, thereby controlling the release timing of the magnetic energy accumulated in the first winding and the second winding. When the stepped down operation is performed, the stepped down voltage is output from the winding portion. Therefore, since the step-up operation and the step-down operation can be performed separately by switching the current path, the loss can be reduced when performing the step-up operation as compared with the step-up / step-down chopper type circuit that performs step-up / step-down with the same route. . Further, since the current input to the circuit element can be reduced as compared with the step-up / step-down chopper method, the power capacity required for the circuit element can be reduced, and the circuit can be reduced in size. In addition, when performing the boosting operation, the power factor can be improved by switching the path by the path switching unit so that the input current is not interrupted and the waveform of the input current is similar to the waveform of the input voltage. It can be carried out. Furthermore, since the rectifier rectifies the input voltage to a voltage having a predetermined polarity, it is not necessary to change the operation of the circuit depending on the polarity of the input voltage, and the operation can be performed with simple control.

  According to the step-up / step-down circuit according to the second aspect of the present invention, in the step-up / step-down circuit according to the first aspect, in particular, in the step-down operation, the path switching unit switches the current path. The current output from the second winding is supplied to the load.

  According to the step-up / step-down circuit according to the second aspect, in the step-down operation, when the path switching unit switches the current path, the input current flows through the first winding, so that the first winding and the second winding The magnetic energy stored in the second winding is supplied to the load as an induced current from the second winding. As a result, the step-down operation can be performed without directly supplying the input current to the second winding, so that the circuit can be further miniaturized by omitting the current supply circuit to the second winding. .

  The step-up / step-down circuit according to a third aspect of the present invention is the step-up / step-down circuit according to the first or second aspect, in particular, the path switching unit is a path that passes through the first winding and does not pass through the load. And a second switch element for turning on and off the current flowing through the first winding and the load.

  According to the step-up / step-down circuit according to the third aspect, the first switch element turns on and off the current flowing through the path through the first winding and not through the load. The second switch element turns on and off the current flowing through the first winding and the load. Therefore, by controlling the first switch element and the second switch element, it is possible to control the timing for accumulating magnetic energy in the winding portion and the timing for supplying the accumulated magnetic energy to the load. . Therefore, if these switching elements are appropriately switched, it is possible to perform a step-up operation or a step-down operation with a simple circuit.

  The step-up / step-down circuit according to the fourth aspect of the present invention is the step-up / step-down circuit according to the third aspect, in particular, the step-up operation is such that the first switch element is on and the second switch element is off. The step-down operation is performed by switching between a state and a state where the first switch element is off and the second switch element is on, and the step-down operation is performed when the first switch element is off and the second switch element is off It is performed by switching between a state in which an element is on and a state in which the first switch element is off and the second switch element is off.

  According to the step-up / step-down circuit according to the fourth aspect, magnetic energy is accumulated in the winding portion in the step-up operation by switching the state by these switch elements, and the induction generated in the first winding by the magnetic energy is generated. Since the voltage is increased to the input voltage and output to the load, the boosted voltage can be output to the load by simple switch control. Since the input current flowing through the first winding is not interrupted during this boosting operation, the path switching unit switches the path so that the waveform of the input current is similar to the waveform of the input voltage. The power factor can be improved. Also, in the step-down operation, magnetic energy is accumulated in the winding part, and the induced voltage generated by the magnetic energy is output from the second winding, so that the voltage stepped down to the load is output by simple switch control. Can do.

  The buck-boost circuit according to the fifth aspect of the present invention is the buck-boost circuit according to the third or fourth aspect, in particular, the first winding is connected to one of the output ends of the rectifier. The first winding element has a first end and a second end, the second winding has a first end and a second end connected to one end side of the load. A connection node between the second end of the first winding and the second switch, and the other of the output ends of the rectifying unit, the second end of the second winding, and one end side of the load The second switch element is connected between connection nodes, and the second switch element includes a connection node between a second end of the first winding and the first switch, and a first end of the second winding and the It is connected between the connection nodes with the other end side of the load.

  According to the step-up / step-down circuit according to the fifth aspect, with these circuit configurations, the winding portion can be boosted only by performing easy switch control of controlling on / off of the first switch element and the second switch element. The step-up operation for outputting the voltage to the load and the step-down operation for outputting the voltage stepped down by the winding to the load can be performed. Therefore, it is possible to realize a step-up / step-down circuit capable of improving the power factor with a simple circuit configuration while reducing the size and reducing the loss.

  A power conversion device according to a sixth aspect of the present invention includes an input terminal to which an input voltage is input from a power supply, an output terminal, and a voltage obtained by stepping up or stepping down the input voltage and stepping up or stepping down the load from the output end to a load. A step-up / step-down circuit that outputs a rectifying unit that rectifies the input voltage to a voltage having a predetermined polarity, and a first winding and a second winding that are magnetically coupled to each other. A winding portion that includes a wire and the voltage rectified by the rectifying portion is applied to the first winding, and a step-up operation that outputs a boosted voltage from the winding portion, or the winding portion is stepped down. A path switching unit that switches a path of a current flowing through the step-up / step-down circuit in order to perform a step-down operation that outputs the generated voltage, and by switching the current path by the path switching unit, the step-up operation and In the step-down operation, the Current flows from the source, characterized in that the flow through the first winding.

  According to the power conversion device of the sixth aspect, the rectifier performs rectification so that the input voltage input from the power supply becomes a voltage of a predetermined polarity. The winding unit receives the voltage rectified by the rectifying unit in the first winding, and accumulates magnetic energy in the first winding and the second winding that are magnetically coupled to each other. When the step-up operation is performed by controlling the release timing of the magnetic energy accumulated in the first winding and the second winding by the path switching unit switching the current path, the winding unit When the voltage is stepped down, the voltage stepped down from the winding unit is output to the output terminal. Therefore, since the step-up operation and the step-down operation are performed separately by switching the current path, the loss can be reduced compared to the step-up / step-down chopper circuit that performs the step-up / step-down operation using the same route. . Further, since the current input to the circuit element can be reduced as compared with the step-up / step-down chopper method, the power capacity required for the circuit element can be reduced, and the circuit can be reduced in size. In addition, when performing the boosting operation, the power factor can be improved by switching the path by the path switching unit so that the input current is not interrupted and the waveform of the input current is similar to the waveform of the input voltage. It can be carried out. Furthermore, since the rectifier unit sets the input voltage to a voltage having a predetermined polarity, it is not necessary to change the operation of the circuit depending on the polarity of the input voltage, and therefore it can be operated with simple control.

  According to the present invention, it is possible to obtain a step-up / step-down circuit and a power conversion device capable of improving the power factor while reducing the size and reducing the loss.

It is the figure which showed schematically the structure of the power converter device which concerns on the 1st Embodiment of this invention. It is a figure which shows the path | route through which the electric current flows in 1st polarity pressure | voltage rise operation. It is the figure which showed the relationship between the electric current and voltage in 1st polarity boosting operation | movement. It is a figure which shows the path | route through which the electric current flows in 2nd polarity pressure | voltage rise operation. It is the figure which showed the relationship between the electric current and voltage in 2nd polarity step-up operation. It is a figure which shows the path | route through which the electric current flows in 1st polarity step-down operation. It is the figure which showed the relationship between the electric current and voltage in 1st polarity step-down operation. It is a figure which shows the path | route into which the electric current flows in 2nd polarity step-down operation. It is the figure which showed the relationship between the electric current and voltage in 2nd polarity step-down operation. It is the figure which showed the switching timing of operation | movement of a step-up / step-down circuit when the output voltage of a step-up / step-down circuit is a predetermined value. It is the figure which showed schematically the structure of the power converter device which concerns on the 2nd Embodiment of this invention. It is a figure which shows the path | route through which the electric current flows in pressure | voltage rise operation | movement. It is the figure which showed the relationship between the electric current and voltage in a pressure | voltage rise operation. It is a figure which shows the path | route through which the electric current flows in pressure | voltage fall operation | movement. It is the figure which showed the relationship between the electric current and voltage in step-down operation. It is the figure which showed the switching timing of operation | movement of a step-up / step-down circuit when the output voltage of a step-up / step-down circuit is a predetermined value.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the element which attached | subjected the same code | symbol in different drawing shall show the same or corresponding element.

<First Embodiment>
FIG. 1 is a diagram schematically showing a configuration of a power conversion device 101 according to the first embodiment of the present invention. The power conversion device 101 includes a noise filter 51, a step-up / down circuit 52, a power transmission insulating circuit 53, an input end 54, and an output end 55. The step-up / step-down circuit 52 includes a winding part 11, a path switching part 12, a rectifying part 13, a smoothing part 14, a control part 15, and a capacitor C2. The path switching unit 12 includes switch elements Q1 to Q4 and diodes D1 and D2. The rectifying unit 13 includes diodes D3 to D6. The smoothing unit 14 includes a capacitor C1. Winding portion 11 has a common core and includes winding L1 and winding L2 that are magnetically coupled to each other. The winding part 11 is, for example, a two-winding reactor. The switch elements Q1 to Q4 are, for example, IGBTs (Insulated Gate Bipolar Transistors).

  One end of the output side of the noise filter 51 is connected to the first end of the winding L1. The other end on the output side of the noise filter 51 is connected to a node P1, which is a connection node between the collector of the switch element Q2, the cathode of the diode D2, and the collector of the switch element Q4.

  The switch element Q1 has a gate connected to the node P2 that is a connection node between the gate that receives the control signal from the control unit 15, the second end of the winding L1, the cathode of the diode D1, and the collector of the switch element Q3. It has an anode connected to a node P3, which is a connection node between the anode of the diode D1, the emitter of the switching element Q2, the anode of the diode D2, and one end on the input side of the power transmission insulating circuit 53.

  Switch element Q2 has a gate for receiving a control signal from control unit 15, a collector connected to node P1, and an emitter connected to node P3.

  Switch element Q3 is a connection node between a gate that receives a control signal from control unit 15, a collector connected to node P2, an emitter of switch element Q4, and the other end on the input side of power transmission insulating circuit 53. And an emitter connected to node P4.

  Switch element Q4 has a gate for receiving a control signal from control unit 15, a collector connected to node P1, and an emitter connected to node P4.

  The diodes D3 to D6 of the rectifying unit 13 configure a diode bridge so that the current output from the winding L2 flows according to the polarity of the load 202. Note that the polarity of the load 202 is a polarity in which the potential of the node P4 is higher than the potential of the node P3 and the node P4.

  Capacitor C1 is connected between one end and the other end of the input side of power transmission insulating circuit 53. The capacitor C2 is connected between one end and the other end of the output side of the noise filter 51.

  The power conversion device 101 converts the AC voltage supplied from the AC power source 201 into a DC voltage and supplies the DC voltage to the load 202. The load 202 is a driving main power source (battery) such as EV and plug-in type HV.

  An AC voltage is input from the AC power supply 201 to the input terminal 54. The noise filter 51 electrically connected to the input terminal 54 removes the AC voltage noise and outputs it to the step-up / step-down circuit 52.

  The AC voltage input to the step-up / step-down circuit 52 is subjected to noise removal by the capacitor C2. The step-up / down circuit 52 transforms the AC voltage into a DC voltage of an arbitrary level and outputs it to the power transmission insulating circuit 53. The power transmission insulating circuit 53 outputs a DC voltage set to an arbitrary level to the output terminal 55 while performing insulation between the step-up / step-down circuit 52 and the output terminal 55. From the output terminal 55, the DC voltage is output as an output voltage. At this time, the power transmission insulating circuit 53 functions as a load for the step-up / step-down circuit 52.

  The voltage transformation performed by the step-up / step-down circuit 52 will be described more specifically. In the step-up / step-down circuit 52, the controller 15 controls the on / off of the switch elements Q1 to Q4 by inputting a control signal to the switch elements Q1 to Q4. By this switching control, the step-up / step-down circuit 52 causes the current flowing through the winding L1 to flow through a path that does not pass through the capacitor C1 and the power transmission insulating circuit 53, and the current flowing through the winding L1 to the capacitor C1 and the power transmission circuit. Switching between a state of flowing through the path through the insulating circuit 53 and a state of no current flowing through the winding L1 is performed. By switching the current flow path, the step-up / step-down circuit 52 performs a step-up operation for outputting the stepped-up output voltage and a step-down operation for outputting the stepped-down output voltage.

  First, the boosting operation performed by the step-up / down circuit 52 will be described. The step-up / step-down circuit 52 performs the first polarity boosting operation when performing the boosting operation when the input voltage from the AC power supply 201 has the first polarity, and the boosting operation when the input voltage has the second polarity. When performing the above, the second polarity boosting operation is performed. Note that the first polarity is the polarity of the input voltage such that the potential of the node P2 is higher than the potential of the node P1 and the node P2. The second polarity is the polarity of the input voltage that compares the potentials of the nodes P1 and P2 so that the potential of the node P1 is higher.

  When performing the first polarity boosting operation, the control unit 15 performs control so that the switch element Q2 and the switch element Q4 are turned off. Then, when the control unit 15 performs switching control of the switch elements Q1 and Q3, the step-up / step-down circuit 52 outputs the boosted voltage to the power transmission insulating circuit 53. The switching control of the switch element Q1 and the switch element Q3 in the first polarity boosting operation includes a state where the switch element Q1 is on and the switch element Q3 is off, and a state where the switch element Q1 is off and the switch element Q3 is on And switching.

  FIG. 2 is a diagram illustrating a current flow path in the first polarity boosting operation. The voltage Vin1 is an input voltage of the step-up / step-down circuit 52. The voltage Vout1 is an output voltage of the step-up / step-down circuit 52. The current Iin1 is an input current of the step-up / step-down circuit 52.

  When the switch element Q1 is on and the switch element Q3 is off, the voltage Vin1 is applied to the step-up / down circuit 52 to generate a current Iin1. This current Iin1 flows through a path through the winding L1, the switching element Q1, and the diode D2. That is, the current Iin1 flows through the path indicated by the thick solid arrow in FIG. At this time, when the current Iin1 flows through the winding L1, a magnetic flux Φ is generated in the winding L1, and magnetic energy is accumulated in the winding L1 and the winding L2 magnetically coupled to the winding L1.

  When the switch element Q1 is off and the switch element Q3 is on, the current Iin1 is supplied to the capacitor C1 and the power transmission insulating circuit 53 via the winding L1 and the switch element Q3. The output voltage of the step-up / step-down circuit 52 is smoothed by the capacitor C 1, and a DC voltage is output to the power transmission insulating circuit 53. At this time, the current Iin1 flows through the path indicated by the dotted arrow in FIG. Since the current Iin1 flows through the winding L1, it has a current value based on the magnetic flux Φ generated in the winding L1 and the winding L2.

  FIG. 3 is a diagram showing a relationship between current and voltage in the first polarity boosting operation. In FIG. 3, a current IQ1 is a current flowing through the switch element Q1. The current IQ3 is a current that flows through the switch element Q3. In FIG. 3, a period in which the switch element Q1 is on and the switch element Q3 is off is a period Ton, and a period in which the switch element Q1 is off and the switch element Q3 is on is a period Toff.

  Even when the period Ton and the period Toff are switched, the magnetic flux Φ generated in the winding L1 continuously changes. Further, since the current Iin1 does not flow through the power transmission insulating circuit 53 in the period Ton and the current Iin1 flows through the power transmission insulating circuit 53 in the period Toff, the current Iin1 follows the increase / decrease in the voltage Vin1. The waveform increases in the period Ton and decreases in the period Toff. Therefore, by performing switching with adjusted frequency, the current Iin1 becomes a waveform similar to the waveform of the voltage Vin1, and the power factor of the step-up / step-down circuit 52 is improved. The switching frequency at this time is, for example, several kHz to several tens of kHz.

と表される。 At this time, the relationship between the change amount ΔΦ1 of the magnetic flux Φ in the period Ton and the effective voltage Vein1 of the input voltage Vin1 is expressed by using the number of turns n1 of the winding L1.

It is expressed.

と表される。 Further, the relationship between the change amount ΔΦ2 of the magnetic flux Φ in the period Toff, the effective voltage Vein1 of the input voltage Vin1, and the effective voltage Veout1 of the output voltage Vout1 is as follows.

It is expressed.

となる。 When the switching between the period Ton and the period Toff is repeatedly performed and the circuit operation of the step-up / step-down circuit 52 is in a steady state, the change amount ΔΦ1 and the change amount ΔΦ2 can be regarded as the same amount. The relationship with the voltage Vout1 is

It becomes.

  Therefore, the input / output voltage ratio Veout1 / Vein1 of the step-up / step-down circuit 52 in the first polarity boosting operation is set by the ratio between the on time and the off time in switching of the switch element Q1 and the switch element Q3. In accordance with this setting, the output voltage of the step-up / step-down circuit 52 is boosted to an arbitrary level and output to the power transmission insulating circuit 53. In this way, the first polarity boosting operation is performed.

  Further, when the step-up / step-down circuit 52 performs the second polarity boosting operation, the control unit 15 performs control so that the switch element Q1 and the switch element Q3 are turned off. Then, when the control unit 15 performs switching control of the switch element Q2 and the switch element Q4, the step-up / step-down circuit 52 outputs the boosted voltage to the power transmission insulating circuit 53. The switching control of the switch element Q2 and the switch element Q4 in the second polarity boosting operation includes a state where the switch element Q2 is on and the switch element Q4 is off, and a state where the switch element Q2 is off and the switch element Q4 is on And switching.

  FIG. 4 is a diagram illustrating a current flow path in the second polarity boosting operation. The voltage Vin2 is an input voltage of the step-up / step-down circuit 52. The voltage Vout2 is an output voltage of the step-up / down circuit 52. The current Iin2 is an input current of the buck-boost circuit 52.

  When the switch element Q2 is on and the switch element Q4 is off, the voltage Vin2 is applied to the step-up / down circuit 52 to generate a current Iin2. This current Iin2 flows through a path through the winding L1, the switch element Q2, and the diode D1. That is, the current Iin2 flows through the path indicated by the thick solid arrow in FIG. At this time, when the current Iin2 flows through the winding L1, a magnetic flux Φ is generated in the winding L1, and magnetic energy is accumulated in the winding L1 and the winding L2.

  When the switch element Q2 is off and the switch element Q4 is on, the current Iin2 is supplied to the capacitor C1 and the power transmission insulating circuit 53 via the winding L1 and the switch element Q4. The output voltage of the step-up / step-down circuit 52 is smoothed by the capacitor C 1, and a DC voltage is output to the power transmission insulating circuit 53. At this time, the current Iin2 flows through the path indicated by the dotted arrow in FIG. Since this current Iin2 flows through the winding L1, it becomes a current value based on the magnetic flux Φ generated in the winding L1 and the winding L2.

  FIG. 5 is a diagram showing the relationship between current and voltage in the second polarity boosting operation. In FIG. 5, a current IQ2 is a current flowing through the switch element Q2. The current IQ4 is a current that flows through the switch element Q4. In FIG. 5, a period in which the switch element Q2 is on and the switch element Q4 is off is a period Ton, and a period in which the switch element Q2 is off and the switch element Q4 is on is a period Toff.

  Even when the period Ton and the period Toff are switched, the magnetic flux Φ generated in the winding L1 continuously changes. In addition, since the current Iin2 does not flow through the power transmission insulating circuit 53 in the period Ton and the current Iin2 flows through the power transmission insulating circuit 53 in the period Toff, the current Iin2 follows the increase and decrease of the voltage Vin2. The waveform increases in the period Ton and decreases in the period Toff. Therefore, by performing switching with adjusted frequency, the current Iin2 becomes a waveform similar to the waveform of the voltage Vin2, and the power factor of the step-up / step-down circuit 52 is improved. The switching frequency at this time is, for example, several kHz to several tens of kHz.

と表される。 At this time, the relationship between the change amount ΔΦ1 of the magnetic flux Φ in the period Ton and the effective voltage Vein2 of the input voltage Vin2 is expressed using the number n1 of windings L1.

It is expressed.

と表される。 Furthermore, the relationship between the change amount ΔΦ2 of the magnetic flux Φ in the period Toff, the effective voltage Vein2 of the input voltage Vin2, and the effective voltage Veout2 of the output voltage Vout2 is

It is expressed.

となる。 Then, when the switching between the period Ton and the period Toff is repeatedly performed and the circuit operation of the step-up / step-down circuit 52 becomes a steady state, the change amount ΔΦ1 and the change amount ΔΦ2 can be regarded as the same amount, and therefore, the effective voltage Vein2 and the effective amount The relationship with the voltage Vout2 is

It becomes.

  Therefore, the input / output voltage ratio Veout2 / Vein2 of the step-up / step-down circuit 52 in the second polarity boosting operation is set by the ratio between the on time and the off time in switching of the switch element Q2 and the switch element Q4. In accordance with this setting, the output voltage of the step-up / step-down circuit 52 is boosted to an arbitrary level and output to the power transmission insulating circuit 53. In this way, the second polarity boosting operation is performed.

  Next, the step-down operation performed by the step-up / down circuit 52 will be described. The step-up / step-down circuit 52 performs the first polarity step-down operation when performing the step-down operation when the input voltage from the AC power supply 201 is the first polarity, and performs the step-down operation when the input voltage is the second polarity. When performing the above, the second polarity step-down operation is performed.

  When performing the first polarity step-down operation, the control unit 15 performs control so that the switch elements Q1, Q2, and Q4 are turned off. Then, when the control unit 15 performs switching control of the switch element Q3, the step-up / step-down circuit 52 outputs the reduced voltage to the power transmission insulating circuit 53.

  FIG. 6 is a diagram illustrating a current flow path in the first polarity step-down operation. The voltage Vin3 is an input voltage of the step-up / step-down circuit 52. The voltage Vout3 is an output voltage of the step-up / step-down circuit 52. The current Iin3 is an input current of the step-up / step-down circuit 52.

  When the switch element Q3 is on, the voltage Vin3 is applied to the step-up / step-down circuit 52 to generate a current Iin3. The current Iin3 flows through a path through the winding L1, the switch element Q3, the capacitor C1, the power transmission insulating circuit 53, and the diode D2. That is, the current Iin3 flows through the path indicated by the thick solid arrow in FIG. At this time, a magnetic flux Φ is generated in the winding L1 due to the current Iin3 flowing through the winding L1, and magnetic energy is accumulated in the winding L1 and the winding L2.

  Since the current Iin3 is interrupted while the switch element Q3 is off, an induced voltage is generated in the winding L2 by self-induction. With this induced voltage, a current IC flows in the direction of the dotted arrow shown in FIG. That is, the current IC flows through the path through the diode D5, the capacitor C1, the power transmission insulating circuit 53, and the diode D4 by the magnetic energy stored in the winding L2. This current IC supplies power to the capacitor C1 and the power transmission insulating circuit 53, and the output voltage of the step-up / step-down circuit 52 is smoothed.

  FIG. 7 is a diagram showing a relationship between current and voltage in the first polarity step-down operation. In FIG. 7, a period in which the switch element Q3 is on is a period Ton, and a period in which the switch element Q3 is off is a period Toff.

  Referring to FIG. 7, during the period Ton, the current Iin3 flows according to the voltage Vin3 that is an AC voltage, and thus the current Iin3 has a waveform that follows the voltage Vin3. Therefore, by performing switching with adjusted frequency, the current Iin3 becomes a waveform similar to the waveform of the voltage Vin3, and the power factor of the step-up / step-down circuit 52 is improved. The switching frequency at this time is, for example, several kHz to several tens of kHz.

  The current IC flows according to the induced voltage of the winding L2 while the switch element Q3 is off. Therefore, as the induced voltage decreases, the current IC also decreases. Since the magnetic flux Φ is a magnetic flux shared by the winding L1 and the winding L2, it is not turned on / off by switching of the switch element Q3, but continuously changes according to the current Iin3 and the current IC. The output voltage Vout3 is smoothed by the capacitor C1 and output as a DC voltage.

と表される。 At this time, the relationship between the effective voltage Vein3 of the input voltage Vin3, the effective voltage Veout3 of the output voltage Vout3, and the amount of change ΔΦ1 of the magnetic flux Φ in the period Ton is expressed using the number of turns n1 of the winding L1.

It is expressed.

と表される。 Further, the relationship between the effective voltage Veout3 of the input voltage Vout3 and the amount of change ΔΦ2 of the magnetic flux Φ in the period Toff is expressed using the number of turns n2 of the winding L2.

It is expressed.

となる。 When the switching between the period Ton and the period Toff is repeatedly performed and the circuit operation of the step-up / step-down circuit 52 becomes a steady state, the change amount ΔΦ1 and the change amount ΔΦ2 can be regarded as the same amount, so that the effective voltage of the input voltage The relationship between Vein3 and the effective voltage Veout3 of the output voltage is

It becomes.

  Since the number of turns n1 and the number of turns n2 are constants determined based on the specifications of the winding L1 and the winding L2, the input / output voltage ratio Veout3 / Vein3 of the buck-boost circuit 52 is an on-time in switching of the switch element Q3. And the off time ratio. According to this setting, the output voltage of the step-up / step-down circuit 52 is stepped down to an arbitrary level and output to the power transmission insulating circuit 53. In this way, the first polarity step-down operation is performed.

  Further, when performing the second polarity step-down operation, the control unit 15 performs control so that the switch elements Q1 to Q3 are turned off. Then, when the control unit 15 performs switching control of the switch element Q4, the step-up / step-down circuit 52 outputs the stepped down voltage to the power transmission insulating circuit 53.

  FIG. 8 is a diagram illustrating a path through which a current flows in the second polarity step-down operation. The voltage Vin4 is an input voltage of the buck-boost circuit 52. The voltage Vout4 is an output voltage of the step-up / step-down circuit 52. A current Iin4 is an input current of the step-up / step-down circuit 52.

  When the switch element Q4 is in an on state, the voltage Vin4 is applied to the step-up / down circuit 52 to generate a current Iin4. The current Iin4 flows through a path through the winding L1, the switching element Q4, the capacitor C1, the power transmission insulating circuit 53, and the diode D1. That is, the current Iin4 flows through the path indicated by the thick solid line arrow in FIG. At this time, a magnetic flux Φ is generated in the winding L1 due to the current Iin4 flowing through the winding L1, and magnetic energy is accumulated in the winding L1 and the winding L2.

  Since the current Iin4 is interrupted while the switch element Q4 is off, an induced voltage is generated in the winding L2 by self-induction. Due to this induced voltage, a current IC flows in the direction of the dotted arrow shown in FIG. That is, the current IC flows through a path through the diode D6, the capacitor C1, the power transmission insulating circuit 53, and the diode D3 by the magnetic energy stored in the winding L2. This current IC supplies power to the capacitor C1 and the power transmission insulating circuit 53, and the output voltage of the step-up / step-down circuit 52 is smoothed.

  FIG. 9 is a diagram showing the relationship between current and voltage in the second polarity step-down operation. In FIG. 9, a period in which the switch element Q4 is on is a period Ton, and a period in which the switch element Q4 is off is a period Toff.

  Referring to FIG. 9, during the period Ton, the current Iin4 flows according to the voltage Vin4 that is an AC voltage, and thus the current Iin4 has a waveform that follows the voltage Vin4. Therefore, by performing switching with adjusted frequency, the current Iin4 becomes a waveform similar to the waveform of the voltage Vin4, and the power factor of the step-up / step-down circuit 52 is improved. The switching frequency at this time is, for example, several kHz to several tens of kHz.

  The current IC flows according to the induced voltage of the winding L2 while the switch element Q4 is off. Therefore, as the induced voltage decreases, the current IC also decreases. Since the magnetic flux Φ is a magnetic flux shared by the winding L1 and the winding L2, it is not turned on / off by switching of the switch element Q4, but continuously changes according to the current Iin4 and the current IC. The output voltage Vout4 is smoothed by the capacitor C1 and output as a DC voltage.

と表される。 At this time, the relationship between the effective voltage Vein4 of the input voltage Vin4, the effective voltage Veout4 of the output voltage Vout4, and the amount of change ΔΦ of the magnetic flux Φ in the period Ton is expressed using the number of turns n1 of the winding L1.

It is expressed.

と表される。 Further, the relationship between the effective voltage Veout4 of the input voltage Vout4 and the change amount ΔΦ2 of the magnetic flux Φ in the period Toff is expressed using the number n2 of windings L2.

It is expressed.

となる。 When the switching between the period Ton and the period Toff is repeatedly performed and the circuit operation of the step-up / step-down circuit 52 becomes a steady state, the change amount ΔΦ1 and the change amount ΔΦ2 can be regarded as the same amount, so that the effective voltage of the input voltage The relationship between Vein4 and the effective voltage Veout4 of the output voltage is

It becomes.

  Since the number of turns n1 and the number of turns n2 are constants determined based on the specifications of the winding L1 and the winding L2, the input / output voltage ratio Veout4 / Vein4 of the buck-boost circuit 52 is the on-time in switching of the switch element Q4. And the off time ratio. In accordance with this setting, the output voltage of the step-up / step-down circuit 52 is stepped down to an arbitrary level and output to the power transmission insulating circuit 53. In this way, the second polarity step-down operation is performed.

  The step-up / step-down circuit 52 performs any one of the first polarity step-up operation, the second polarity step-up operation, the first polarity step-down operation, and the second polarity step-down operation. Therefore, when the output voltage is set to a predetermined value, the AC power supply These operating states are switched according to the polarity and magnitude of the input voltage from 202. FIG. 10 is a diagram showing the switching timing of the operation of the step-up / step-down circuit when the output voltage Vout of the step-up / step-down circuit 52 is a predetermined value. In FIG. 10, the input voltage of the step-up / step-down circuit 52 is represented as voltage Vin, the output voltage is represented as voltage Vout, and the first polarity is displayed as the positive direction of the vertical axis.

  Referring to FIG. 10, in period T1, the absolute value of input voltage Vin having the first polarity is equal to or less than the absolute value of output voltage Vout set to a predetermined value. Therefore, by performing the first polarity boosting operation by controlling the switching by the control unit 15, the step-up / step-down circuit 52 boosts the input voltage Vin and outputs an output voltage Vout having a predetermined value.

  In the period T2, the absolute value of the input voltage Vin having the first polarity is larger than the absolute value of the output voltage Vout set to a predetermined value. Therefore, by performing the first polarity step-down operation by controlling the switching by the control unit 15, the step-up / step-down circuit 52 steps down the input voltage Vin and outputs an output voltage Vout having a predetermined value.

  In the period T3, the absolute value of the input voltage Vin having the first polarity is equal to or less than the absolute value of the output voltage Vout set to a predetermined value. Therefore, the step-up / step-down circuit 52 outputs the output voltage Vout having a predetermined value by performing the first polarity boosting operation similarly to the period T1.

  In the period T4, the absolute value of the input voltage Vin having the second polarity is equal to or less than the absolute value of the output voltage Vout set to a predetermined value. Therefore, the step-up / step-down circuit 52 boosts the input voltage Vin and outputs the output voltage Vout having a predetermined value by performing the second polarity boosting operation by controlling the switching by the control unit 15.

  In the period T5, the absolute value of the input voltage Vin having the second polarity is larger than the absolute value of the output voltage Vout set to a predetermined value. Therefore, by performing the second polarity step-down operation by controlling the switching by the control unit 15, the step-up / step-down circuit 52 steps down the input voltage Vin and outputs an output voltage Vout having a predetermined value.

  In the period T6, the absolute value of the input voltage Vin having the second polarity is equal to or less than the absolute value of the output voltage Vout set to a predetermined value. Therefore, the step-up / step-down circuit 52 outputs the output voltage Vout having a predetermined value by performing the second polarity boosting operation similarly to the period T4.

  Thus, depending on the polarity of the input voltage Vin input from the AC power supply 201 and the magnitude relationship between the absolute values of the input voltage Vin and the output voltage Vout, whether the step-up / step-down circuit 52 performs the step-up operation or the step-down operation is determined. By switching, the step-up / step-down circuit 52 outputs an output voltage that is a predetermined value even if the input voltage Vin increases or decreases.

  Although the case where the input voltage to the step-up / step-down circuit 52 is a sine wave is illustrated, the input voltage is not limited to a sine wave in the present invention. The buck-boost circuit 52 switches the operation of the buck-boost circuit 52 according to the polarity of the input voltage and the magnitude relationship between the input voltage, the output voltage, and the absolute value, so that the output voltage is a predetermined value even if the input voltage has another waveform. Is output.

  As described above, the step-up / down circuit 52 switches the switching elements Q1 to Q4 by the control unit 15 regardless of whether the polarity of the input voltage from the AC power supply 201 is the first polarity or the second polarity. By controlling the above, it becomes possible to output the boosted or stepped down DC voltage to the power transmission insulating circuit 53. Therefore, the power conversion device 101 can convert the input AC power into DC power by outputting the DC voltage to the load 202 via the power transmission insulating circuit 53. Therefore, the power conversion device 101 according to the embodiment of the present invention does not need to use a full-wave rectifier circuit when performing step-up / step-down of the input voltage, and thus reduces loss compared to the case of using a full-wave rectifier circuit. It is possible.

  Note that the power input to the power conversion apparatus 101 is not limited to AC power, and DC power may be input. In this case, the operation of either the first polarity or the second polarity of the AC power supply 201 described in the present embodiment is performed, and the output DC voltage is set to an arbitrary level. Can do.

  The power conversion device 101 according to the first embodiment of the present invention includes a boosting operation for boosting by a so-called boosting chopper method with a simple circuit configuration by using the magnetically coupled winding L1 and winding L2. It is possible to switch between a step-down operation for performing step-down by a so-called step-down chopper method. Therefore, in order to obtain the same level of output current, the step-up / step-down circuit 52 requires less current to input than a circuit that performs boosting by the so-called step-up / step-down chopper method. Therefore, the ripple current generated by the switching of the step-up / down circuit 52 is reduced, and the loss can be reduced. Further, since the current input to the circuit element can be reduced as compared with the step-up / step-down chopper method, the power capacity required for each circuit element can be reduced, and the circuit can be miniaturized.

  Furthermore, since there is no period during which the input current is cut off when the boosting operation is performed, the waveform of the input current can be compared with the step-up / step-down chopper circuit by appropriately setting the switching frequency of the switch element of the path switching unit 12. Since the waveform of the input voltage is more similar to that of the input voltage, the power factor can be improved.

  Further, since the switching element operates by switching the path through which the current flows for each polarity of the input voltage, it is not necessary to use a full-wave rectifier circuit when the input voltage is stepped up or down. Therefore, since there is no loss due to the full-wave rectifier circuit, it is possible to reduce the loss as compared with a step-up / down circuit using the full-wave rectifier circuit. In particular, when performing a step-up operation in which a high current flows through a circuit element, the number of elements through which an input current passes is small during a period in which magnetic energy is accumulated in the winding L1 and the winding L2. That is, in the first polarity boosting operation, current flows only through the winding L1, the switch element Q1, and the diode D2 that store magnetic energy. In the second polarity boosting operation, a current flows only through the winding L1, the switch element Q2, and the diode D1 that store magnetic energy. Therefore, the number of elements through which the input current passes is small and the loss is further reduced in the period in which the magnetic energy requiring a large input current is accumulated.

  In addition, when the first polarity step-down operation and the second polarity step-down operation are performed, the stepped-down voltage is output from the winding L2 magnetically coupled to the winding L1, so that if the input current is supplied to the winding L1, the winding The input current may not be directly supplied to L2. Therefore, an input current supply circuit for the winding L2 becomes unnecessary, and the circuit can be further reduced in size.

  When a current is output from the winding L2, the rectifying unit 13 forms a diode bridge with the diodes D3 to D6, and performs rectification so that the current IC is supplied in accordance with the polarity of the load. Therefore, it is possible to prevent the current output from the winding L2 from flowing in a direction opposite to the polarity of the load, and to appropriately apply the induced voltage generated in the winding L2 to the load. When a current flows through the diodes D3 to D6 of the rectifying unit 13, a loss occurs. However, since the operation is a step-down operation, it is not necessary to increase the input current by adjusting the output voltage level.

<Second Embodiment>
FIG. 11 is a diagram schematically showing the configuration of the power conversion device 102 according to the second embodiment of the present invention. The power conversion device 102 includes a noise filter 51, a step-up / down circuit 56, a power transmission insulating circuit 53, an input end 54, and an output end 55. The step-up / step-down circuit 56 includes a winding part 11, a path switching part 12, a smoothing part 14, a control part 15, a full-wave rectification part 16, a cutoff part 17, and a capacitor C <b> 2. Path switching unit 12 includes switch elements Q5 and Q6. The smoothing unit 14 includes a capacitor C1. Full-wave rectification unit 16 includes diodes D7 to D10. The blocking unit 17 includes a diode D11. Winding portion 11 has a common core and includes winding L1 and winding L2 that are magnetically coupled to each other. The winding part 11 is, for example, a two-winding reactor. The switch elements Q5 and Q6 are, for example, IGBTs (Insulated Gate Bipolar Transistors).

  The output side of the noise filter 51 is connected to a diode bridge formed by diodes D7 to D10 that are the full-wave rectification unit 16. One end on the output side of the full-wave rectifying unit 16 is connected to the first end of the winding L1.

  Switch element Q5 has a gate for receiving a control signal from control unit 15, a collector connected to the second end of winding L1 and the collector of switch element Q6, and the other end on the output side of full-wave rectification unit 16 and a diode. An emitter connected to the anode of D11 and one end of the input side of the power transmission insulating circuit 53 is provided.

  The switch element Q6 includes a gate for receiving a control signal from the control unit 15, a collector connected to the second end of the winding L1 and the collector of the switch element Q5, and a first end of the winding L2 and an insulating circuit for power transmission. 53 having an emitter connected to the other end of the input side.

  Capacitor C1 is connected between one end and the other end of the input side of power transmission insulating circuit 53. Capacitor C2 is connected between one end and the other end on the output side of full-wave rectifier 16.

  The power converter 102 converts the AC voltage supplied from the AC power source 201 into a DC voltage and supplies the DC voltage to the load 202. The load 202 is a driving main power source (battery) such as EV and plug-in type HV.

  An AC voltage is input from the AC power supply 201 to the input terminal 54. The noise filter 51 electrically connected to the input terminal 54 removes the AC voltage noise and outputs it to the step-up / down circuit 56.

  The step-up / down circuit 56 full-wave rectifies the AC voltage received from the noise filter 51 by the full-wave rectification unit 16. The full-wave rectified input voltage is subjected to noise removal by the capacitor C2. Then, the step-up / step-down circuit 56 converts the full-wave rectified input voltage into a DC voltage of an arbitrary level and outputs it to the power transmission insulating circuit 53. The power transmission insulating circuit 53 outputs a DC voltage set to an arbitrary level to the output terminal 55 while performing insulation between the step-up / step-down circuit 56 and the output terminal 55. From the output terminal 55, the DC voltage is output as an output voltage. At this time, the power transmission insulating circuit 53 functions as a load for the step-up / step-down circuit 52.

  The power conversion performed by the step-up / down circuit 56 will be described more specifically. In the step-up / down circuit 56, the control unit 15 controls the on / off of the switch elements Q5 and Q6 by inputting a control signal to the switch elements Q5 and Q6. By this switching control, the step-up / step-down circuit 56 causes the current flowing through the winding L1 to flow through a path that does not pass through the capacitor C1 and the power transmission insulating circuit 53, and the current flowing through the winding L1 to the capacitor C1 and the power transmission circuit. Switching between a state of flowing through the path through the insulating circuit 53 and a state of no current flowing through the winding L1 is performed. By switching the current flow path, the step-up / step-down circuit 56 performs a step-up operation for outputting the stepped-up output voltage and a step-down operation for outputting the stepped-down output voltage.

  First, the boosting operation performed by the step-up / down circuit 56 will be described. When the boosting operation is performed, the control unit 15 controls the switching of the switch element Q5 and the switch element Q6, whereby the step-up / step-down circuit 56 outputs the boosted voltage to the power transmission insulating circuit 53. The switching of the switch element Q5 and the switch element Q6 in this boosting operation refers to switching between a state where the switch element Q5 is on and the switch element Q6 is off and a state where the switch element Q5 is off and the switch element Q6 is on. Is what you do.

  FIG. 12 is a diagram illustrating a path through which a current flows in the boosting operation. The voltage Vin <b> 5 is input from the AC power supply 201 to the step-up / step-down circuit 56 and is full-wave rectified by the full-wave rectification unit 16. The voltage Vout5 is an output voltage of the step-up / down circuit 56. A current Iin5 is an input current of the buck-boost circuit 56.

  When switch element Q5 is on and switch element Q6 is off, voltage Vin5 is input to winding L1 to generate current Iin5. This current Iin5 flows through a path through the winding L1, the switch element Q5, and the full-wave rectification unit 16. That is, the current Iin5 flows through the path indicated by the thick solid arrow in FIG. At this time, when the current Iin5 flows through the winding L1, a magnetic flux Φ is generated in the winding L1, and magnetic energy is accumulated in the winding L1 and the winding L2 magnetically coupled to the winding L1.

  When the switch element Q5 is off and the switch element Q6 is on, the current Iin5 is supplied to the capacitor C1 and the power transmission insulating circuit 53 via the winding L1 and the switch element Q6. The output voltage of the step-up / step-down circuit 56 is smoothed by the capacitor C 1, and a DC voltage is output to the power transmission insulating circuit 53. At this time, the current Iin5 flows through the path indicated by the dotted arrow in FIG. Since this current Iin5 flows through the winding L1, it becomes a current value based on the magnetic flux Φ generated in the winding L1 and the winding L2.

  FIG. 13 is a diagram showing the relationship between current and voltage in the boosting operation. In FIG. 13, a current IQ5 is a current flowing through the switch element Q5. The current IQ6 is a current that flows through the switch element Q6. In FIG. 13, a period in which the switch element Q5 is on and the switch element Q6 is off is a period Ton, and a period in which the switch element Q5 is off and the switch element Q6 is on is a period Toff.

  Even when the period Ton and the period Toff are switched, the magnetic flux Φ generated in the winding L1 continuously changes. Further, since the current Iin5 does not flow through the power transmission insulating circuit 53 in the period Ton and the current Iin5 flows through the power transmission insulating circuit 53 in the period Toff, the current Iin5 follows the increase and decrease of the voltage Vin5. The waveform increases in the period Ton and decreases in the period Toff. Therefore, by performing switching with the frequency adjusted, the current Iin5 becomes a waveform similar to the waveform of the voltage Vin5, and the power factor of the step-up / down circuit 56 is improved. The switching frequency at this time is, for example, several kHz to several tens of kHz.

と表される。 At this time, the relationship between the change amount ΔΦ1 of the magnetic flux Φ in the period Ton and the effective voltage Vein5 of the input voltage Vin5 is expressed using the number of turns n1 of the winding L1.

It is expressed.

と表される。 Furthermore, the relationship between the change amount ΔΦ2 of the magnetic flux Φ in the period Toff, the effective voltage Vein5 of the input voltage Vin5, and the effective voltage Veout5 of the output voltage Vout5 is

It is expressed.

となる。 When the switching between the period Ton and the period Toff is repeatedly performed and the circuit operation of the step-up / step-down circuit 56 is in a steady state, the change amount ΔΦ1 and the change amount ΔΦ2 can be regarded as the same amount. The relationship with the voltage Vout5 is

It becomes.

  Therefore, the input / output voltage ratio Veout5 / Vein5 of the step-up / step-down circuit 56 in the boosting operation is set by the ratio between the on time and the off time in switching of the switch element Q5 and the switch element Q6. In accordance with this setting, the output voltage of the step-up / step-down circuit 56 is boosted to an arbitrary level and output to the power transmission insulating circuit 53. In this way, the boosting operation is performed.

  Next, the step-down operation performed by the step-up / step-down circuit 56 will be described. When performing the step-down operation, the control unit 15 performs control so that the switch element Q5 is turned off. Then, when the control unit 15 performs switching control of the switch element Q6, the step-up / step-down circuit 56 outputs the stepped-down voltage to the power transmission insulating circuit 53.

  FIG. 14 is a diagram illustrating a path through which a current flows in the step-down operation. The voltage Vin6 is a voltage that is input from the AC power supply 201 to the step-up / step-down circuit 56 and rectified by the full-wave rectification unit 16. The voltage Vout6 is an output voltage of the step-up / down circuit 56. A current Iin6 is an input current of the step-up / step-down circuit 56.

  When the switch element Q6 is in the on state, the voltage Vin6 is input to the winding L1 to generate the current Iin6. The current Iin6 flows through a path through the winding L1, the switching element Q6, the capacitor C1, the power transmission insulating circuit 53, and the full-wave rectification unit 16. That is, the current Iin6 flows through the path indicated by the thick solid arrow in FIG. At this time, when the current Iin6 flows through the winding L1, a magnetic flux Φ is generated in the winding L1, and magnetic energy is accumulated in the winding L1 and the winding L2.

  Then, since the current Iin6 is cut off while the switch element Q6 is off, an induced voltage is generated in the winding L2 by self-induction. With this induced voltage, a current IC flows in the direction of the dotted arrow shown in FIG. That is, the current IC flows through the path through the diode D11, the capacitor C1, and the power transmission insulating circuit 53 by the magnetic energy stored in the winding L2. This current IC supplies power to the capacitor C1 and the power transmission insulating circuit 53, and the output voltage of the step-up / down circuit 56 is smoothed.

  FIG. 15 is a diagram showing the relationship between current and voltage in the step-down operation. In FIG. 15, a period in which the switch element Q6 is on is a period Ton, and a period in which the switch element Q6 is off is a period Toff.

  Referring to FIG. 15, during period Ton, current Iin6 flows in accordance with voltage Vin6, which is a full-wave rectified voltage, and thus current Iin6 has a waveform that follows voltage Vin6. Therefore, by performing switching with the frequency adjusted, the current Iin6 becomes a waveform similar to the waveform of the voltage Vin6, and the power factor of the step-up / step-down circuit 56 is improved. The switching frequency at this time is, for example, several kHz to several tens of kHz.

  The current IC flows according to the induced voltage of the winding L2 while the switch element Q6 is off. Therefore, as the induced voltage decreases, the current IC also decreases. Since the magnetic flux Φ is a magnetic flux shared by the winding L1 and the winding L2, it is not turned on / off by switching of the switch element Q3, but continuously changes according to the current Iin6 and the current IC. The output voltage Vout6 is smoothed by the capacitor C1 and output as a DC voltage.

と表される。 At this time, the relationship between the effective voltage Vein6 of the input voltage Vin6, the effective voltage Veout6 of the output voltage Vout6, and the amount of change ΔΦ1 of the magnetic flux Φ in the period Ton is expressed using the number of turns n1 of the winding L1.

It is expressed.

と表される。 Further, the relationship between the effective voltage Veout6 of the input voltage Vout6 and the change amount ΔΦ2 of the magnetic flux Φ in the period Toff can be expressed by using the number of turns n2 of the winding L2.

It is expressed.

となる。 When the switching between the period Ton and the period Toff is repeatedly performed and the circuit operation of the step-up / step-down circuit 56 becomes a steady state, the change amount ΔΦ1 and the change amount ΔΦ2 can be regarded as the same amount, and thus the effective voltage of the input voltage The relationship between Vein 6 and the effective voltage Veout 6 of the output voltage is

It becomes.

  Since the number of turns n1 and the number of turns n2 are constants determined based on the specifications of the winding L1 and the winding L2, the input / output voltage ratio Veout6 / Vein6 of the buck-boost circuit 56 is an on-time in switching of the switch element Q6. And the off time ratio. According to this setting, the output voltage of the step-up / step-down circuit 56 is stepped down to an arbitrary level and output to the power transmission insulating circuit 53. In this way, the step-down operation is performed.

  Since the step-up / step-down circuit 56 performs either one of the step-up operation and the step-down operation, when the output voltage is set to a predetermined value, the step-up / step-down circuit 56 is switched between the step-up operation and the step-down operation depending on the magnitude of the input voltage from the AC power supply 202. . FIG. 16 is a diagram showing the switching timing of the operation of the step-up / step-down circuit when the output voltage Vout of the step-up / step-down circuit 56 is a predetermined value. In FIG. 16, the voltage Vin is a voltage that is input from the AC power supply 201 to the step-up / step-down circuit 56 and rectified by the full-wave rectification unit 16.

  Referring to FIG. 16, in period T7, the absolute value of voltage Vin is equal to or less than the absolute value of output voltage Vout set to a predetermined value. Therefore, by performing the boosting operation by controlling the switching by the control unit 15, the step-up / step-down circuit 56 boosts the input voltage and outputs the output voltage Vout having a predetermined value.

  In the period T8, the absolute value of the voltage Vin is larger than the absolute value of the output voltage Vout set to a predetermined value. Therefore, by performing a step-down operation by controlling switching by the control unit 15, the step-up / step-down circuit 56 steps down the input voltage and outputs an output voltage Vout having a predetermined value.

  In the period T9, the absolute value of the voltage Vin is equal to or less than the absolute value of the output voltage Vout set to a predetermined value. Therefore, the step-up / step-down circuit 56 outputs the output voltage Vout having a predetermined value by performing the boosting operation similarly to the period T7.

  In this way, by switching between the step-up / step-down circuit 56 performing the step-up operation or step-down operation according to the magnitude relationship between the absolute values of the input voltage Vin and the output voltage Vout, the step-up / step-down step is performed even if the input voltage Vin increases or decreases. The circuit 56 outputs an output voltage that is a predetermined value.

  In addition, although the case where the input voltage to the step-up / step-down circuit 56 is a sine wave is illustrated, the input voltage is not limited to a sine wave in the present invention. The step-up / down circuit 56 switches the operation of the step-up / down circuit 56 according to the magnitude relationship between the absolute values of the input voltage and the output voltage, and outputs an output voltage having a predetermined value even if the input voltage has another waveform.

  As described above, the step-up / step-down circuit 56 can control the switching of the switch elements Q5 and Q6 by the control unit 15 to output a stepped-up or step-down DC voltage to the power transmission insulating circuit 53. . Therefore, the power conversion device 102 can convert the input AC power into DC power by outputting the DC voltage to the load 202 via the power transmission insulating circuit 53. Further, since the full-wave rectification unit 16 performs full-wave rectification on the input voltage, there is no need to change the control of the circuit depending on the polarity of the input voltage, and simple switching control for switching on and off of the switch elements Q5 and Q6 is performed. It is possible to output a boosted or stepped down output voltage. Note that the power input to the power converter 102 is not limited to AC power, and DC power may be input.

  The power conversion device 102 according to the second embodiment of the present invention has a boosting operation for boosting by a so-called boosting chopper method with a simple circuit configuration by using the magnetically coupled winding L1 and winding L2. It is possible to switch between a step-down operation for performing step-down by a so-called step-down chopper method. Therefore, in order to obtain an output current of the same level, the step-up / step-down circuit 56 requires less current than a circuit that performs boosting by the so-called step-up / step-down chopper method. Therefore, the ripple current generated by the switching of the step-up / down circuit 56 is reduced, and the loss can be reduced. Further, since the current input to the circuit element can be reduced as compared with the step-up / step-down chopper method, the power capacity required for each circuit element can be reduced, and the circuit can be miniaturized.

  Furthermore, since there is no period during which the input current is cut off when the boosting operation is performed, the waveform of the input current can be compared with the step-up / step-down chopper circuit by appropriately setting the switching frequency of the switch element of the path switching unit 12. Since the waveform of the input voltage is more similar to that of the input voltage, the power factor can be improved.

  When the step-down operation is performed, the stepped-down voltage is output from the winding L2 magnetically coupled to the winding L1, so that if the input current is supplied to the winding L1, the input current is not directly supplied to the winding L2. May be. Therefore, an input current supply circuit for the winding L2 becomes unnecessary, and the circuit can be further reduced in size.

  In addition, the diode D11 of the cutoff unit 17 prevents the current generated by the induced voltage generated in the winding L2 from flowing in the direction opposite to the polarity of the load and the capacitor C1. Therefore, it is possible to appropriately apply the induced voltage generated in the winding L2 to the load and the capacitor C1.

  In the first and second embodiments of the present invention, the case where the winding part 11 is a two-winding reactor is illustrated. However, in the present invention, the winding part 11 may be a transformer or the like. A plurality of windings having a common core and magnetically coupled to each other may be included.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 11 Winding part 12 Path | route switching part 13 Rectification part 14 Smoothing part 15 Control part 16 Full wave rectification part 17 Blocking part 51 Noise filter 52,56 Buck-boost circuit 101,102 Power converter 201 AC power supply 202 Load

Claims (6)

A step-up / step-down circuit for boosting or stepping down an input voltage input from a power supply and supplying the load to a load,
A rectifying unit that rectifies the input voltage to be a voltage of a predetermined polarity;
A winding portion including a first winding and a second winding magnetically coupled to each other, and a voltage rectified by the rectifying portion is applied to the first winding;
A path switching unit that switches a path of a current flowing through the step-up / down circuit in order to perform a step-up operation in which the winding unit outputs a boosted voltage or a step-down operation in which the winding unit outputs a step-down voltage; ,
With
A step-up / step-down circuit in which a current flowing from the power source flows through the first winding in the step-up operation and the step-down operation by switching a current path by the path switching unit.   The step-up / step-down circuit according to claim 1, wherein a current output from the second winding is supplied to the load in the step-down operation by switching a current path by the path switching unit. The route switching unit
A first switch element that turns on and off a current flowing through a path that passes through the first winding and does not pass through the load;
A second switch element for turning on and off a current flowing through the first winding and the load;
The step-up / step-down circuit according to claim 1, comprising: The step-up operation switches between a state in which the first switch element is on and the second switch element is off and a state in which the first switch element is off and the second switch element is on. Is done,
The step-down operation switches between a state in which the first switch element is off and the second switch element is on, and a state in which the first switch element is off and the second switch element is off. The step-up / step-down circuit according to claim 3, wherein The first winding has a first end connected to one of the output ends of the rectification unit, and a second end,
The second winding has a first end and a second end connected to one end side of the load,
The first switch element includes a connection node between the second end of the first winding and the second switch, the other output end of the rectifying unit, and a second end of the second winding. Connected between connection nodes to one end of the load,
The second switch element includes a connection node between the second end of the first winding and the first switch, and a connection between the first end of the second winding and the other end of the load. The step-up / step-down circuit according to claim 3 or 4 connected between nodes. An input terminal to which an input voltage is input from a power source; and
An output end;
A step-up / step-down circuit for stepping up or stepping down the input voltage and outputting a voltage stepped up or stepped down from the output end to a load;
With
The step-up / down circuit is
A rectifying unit that rectifies the input voltage to be a voltage of a predetermined polarity;
A winding portion including a first winding and a second winding magnetically coupled to each other, and a voltage rectified by the rectifying portion is applied to the first winding;
A path switching unit that switches a path of a current flowing through the step-up / down circuit in order to perform a step-up operation in which the winding unit outputs a boosted voltage or a step-down operation in which the winding unit outputs a step-down voltage; ,
With
A power conversion device in which a current flowing from the power source flows through the first winding in the step-up operation and the step-down operation by switching a current path by the path switching unit.

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