JP2012157162A - Insulation circuit for power transmission and power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulation circuit for power transmission capable of reducing switching loss in the circuit of transmitting power while insulating an input side from an output side, and a power converter.SOLUTION: An insulation circuit 101 for power transmission includes: an input switch part 21 including switch elements Z1 and Z2, for supplying power received at a first end of the switch element Z1 and a first end of the switch element Z2 to a storage element C1; an output switch part 22 including switch elements Z3 and Z4, for outputting the power stored in the storage element C1; and a control part 14 for performing at least one of the operation of determining the timing of turning off the switch element Z1 and the switch element Z2 on the basis of a charging current of the storage element C1 and the operation of determining the timing of turning off the switch element Z3 and the switch element Z4 on the basis of the discharge current of the storage element C1.

Description

  The present invention relates to an insulating circuit for power transmission and a power converter, and more particularly to an insulating circuit for power transmission and a power converter that transmit power while insulating between an input side and an output side.

  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.

  Although not intended to charge such a main battery such as an EV, an example of an insulating circuit for a power supply device that converts AC power into DC power is disclosed in, for example, Japanese Patent No. 3595329 (Patent Document 1). Are listed. That is, the power supply device insulating circuit includes a rectifier circuit that converts an AC voltage into a DC voltage, a first capacitor that reduces a pulsating current component remaining in a DC current supplied from the rectifier circuit, and the first capacitor. A first switch circuit that simultaneously opens and closes a positive side and a negative side of a direct current supplied from a capacitor; a second capacitor that stores current supplied from the first switch circuit; and a second capacitor A second switch circuit that simultaneously opens and closes a plus side and a minus side of the supplied direct current; and a third capacitor that holds the current supplied from the second switch circuit and discharges the current to the load side. Further, the ON time is set shorter than the OFF time while the ON time is set to be complementary to the control signal φ1 configured by the square wave set shorter than the OFF time and the control signal φ1. A gate control circuit for generating the control signal φ2 is provided. The first switch circuit is opened and closed by the control signal φ1, and the second switch circuit is opened and closed by the control signal φ2. With such a configuration, an AC voltage can be converted to a DC voltage without using a power transformer that occupies a large volume, and the AC power supply side and the load side can be electrically insulated.

Japanese Patent No. 3595329

  In the insulating circuit for a power supply device described in Patent Document 1, when each switch element in the first switch circuit is turned on, a charge current flows to the second capacitor, and charge starts to be accumulated. When the switch elements are turned off in a state where the charging current is flowing through the second capacitor, a large switching loss is generated based on the product of the charging current and the voltage across the switch elements.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to transmit power that can reduce switching loss in a circuit that transmits power while insulating the input side and the output side. An insulating circuit and a power conversion device are provided.

  In order to solve the above problems, an insulating circuit for power transmission according to an aspect of the present invention is electrically connected to a power storage element having a first end and a second end, a first end, and a first end of the power storage element. A first switch element having a second end connected to the first end, and a second switch element having a first end and a second end electrically connected to the second end of the power storage element, An input switch unit for supplying electric power received at the first end of one switch element and the first end of the second switch element to the power storage element; and a first terminal connected to the first end of the power storage element A third switch element having an end and a second end, and a first switch connected to the second end of the power storage element and a fourth switch element having a second end, and stored in the power storage element An output switch for outputting power and A control unit for controlling on / off of the first switch element to the fourth switch element, the control unit based on a charging current of the power storage element, and the first switch element and the fourth switch element At least one of an operation for determining the timing to turn off the second switch element and an operation for determining the timing to turn off the third switch element and the fourth switch element based on the discharge current of the power storage element is performed. .

  Thus, by monitoring the charging current or discharging current of the storage element, the timing at which these currents become approximately zero is always detected, and each switch element is turned off at the timing when these currents have become approximately zero. Can do. This maximizes the driving frequency of each switch element while reducing the switching loss and improving the power efficiency, thereby enabling high-speed operation. Further, it is not necessary to increase the size of the power storage element, and an increase in circuit area can be prevented. Therefore, switching loss can be reduced in a circuit that transmits power while insulating the input side and the output side.

  Preferably, the power transmission insulating circuit further includes a current detection unit for measuring a charging current and a discharging current of the power storage element, and the control unit is configured to perform the timing based on a measurement result by the current detection unit. To decide.

  In this way, by directly monitoring the current flowing through the storage element, the timing can be obtained more accurately than, for example, a configuration in which the voltage across each storage element is measured and the timing at which the current becomes approximately zero is calculated. Can do. Moreover, since the said timing can be acquired with a simple process, switch control can be performed rapidly. Further, with the configuration in which the current sensor for the power storage element is provided, the timing at which the charging current of the power storage element becomes substantially zero and the timing at which the discharge current of the power storage element becomes substantially zero can be detected by one current sensor.

  Preferably, the control unit turns on the switch elements in the input switch unit and turns off the switch elements in the output switch unit, and sets the switch elements in the input switch unit. The control unit repeats the second period of turning off and turning on each of the switch elements in the output switch unit in order, and the control unit changes the first period when transitioning from the first period to the second period. The switch element and the second switch element are turned off based on the charging current of the power storage element, and the third switch when the transition from the second period to the first period is made At least one of operations for determining the timing of turning off the element and the fourth switch element based on the discharge current of the power storage element is performed.

  With such a configuration, switching loss can be reduced in the operation of transmitting power while insulating the input side and the output side of the power transmission insulating circuit.

  More preferably, the control unit includes the first period, the third period in which the switch elements in the input switch unit and the switch element in the output switch unit are turned off, and the second period. The switch element in the input switch section and the fourth period in which the switch elements in the output switch section are turned off are repeated in this order, and the control section performs the third period from the first period to the third period. An operation for determining the timing to turn off the first switch element and the second switch element based on the charging current of the power storage element, and the transition from the second period to the fourth period A timing for turning off the third switch element and the fourth switch element based on the discharge current of the power storage element. Performing at least one of.

  As described above, by providing the dead time, the insulation between the input side and the output side of the power transmission insulating circuit can be reliably ensured.

  Preferably, the control unit determines the timing for turning off the first switch element and the second switch element based on the charging current of the power storage element, and the operation based on the discharge current of the power storage element. Both the operation of determining the timing for turning off the third switch element and the fourth switch element are performed.

  In this manner, the operation of turning off each switch element in the input switch unit at the timing when the charging current of the storage element becomes substantially zero, and the switch element in the output switch unit being turned off at the timing when the discharge current of the storage element becomes substantially zero With the configuration in which both of the operations are performed, switching loss in the power transmission insulating circuit can be significantly reduced.

  In order to solve the above problems, a power conversion device according to an aspect of the present invention is a power conversion device for converting alternating current power into direct current power and supplying it to a load, and rectifies the received alternating current power. And a power transmission insulating circuit for transmitting the power rectified by the rectifying unit to the load while insulating between the rectifying unit and the load. A power storage element having a first end and a second end, a first switch element connected between the rectification unit and the first end of the power storage element, and the rectification unit and a second end of the power storage element An input switch unit including a second switch element connected in between, and supplying the power rectified by the rectifying unit to the power storage element; a first end connected to a first end of the power storage element; And a third having a second end An output switch unit for outputting electric power stored in the storage element, including a switch element and a fourth switch element having a first end connected to the second end of the storage element and a second end; A control unit for controlling on / off of the first switch element to the fourth switch element, the control unit based on a charging current of the power storage element, and the first switch element and the fourth switch element At least one of an operation for determining the timing to turn off the second switch element and an operation for determining the timing to turn off the third switch element and the fourth switch element based on the discharge current of the power storage element is performed. .

  Thus, by monitoring the charging current or discharging current of the storage element, the timing at which these currents become approximately zero is always detected, and each switch element is turned off at the timing when these currents have become approximately zero. Can do. This maximizes the driving frequency of each switch element while reducing the switching loss and improving the power efficiency, thereby enabling high-speed operation. Further, it is not necessary to increase the size of the power storage element, and an increase in circuit area can be prevented. Therefore, switching loss can be reduced in a circuit that transmits power while insulating the input side and the output side.

  According to the present invention, switching loss can be reduced in a circuit that transmits power while insulating the input side and the output side.

It is a figure which shows the structure of the power converter device which concerns on the 1st Embodiment of this invention. It is a figure which shows the switching operation | movement by the insulation circuit for electric power transmission which concerns on the 1st Embodiment of this invention. It is a figure which shows the electric power transmission operation | movement by the insulating circuit for electric power transmission which concerns on the 1st Embodiment of this invention. It is a figure which shows a gate drive signal and a capacitor current when it assumes that the control part does not perform switch control based on a capacitor current in the insulating circuit for power transmission which concerns on the 1st Embodiment of this invention. It is a figure which shows the gate drive signal and capacitor current in the insulation circuit for electric power transmission which concerns on the 1st Embodiment of this invention. It is a figure which shows the structure of the insulation circuit for electric power transmission which concerns on the 2nd Embodiment of this invention. It is a figure which shows roughly the voltage waveform of each capacitor in the insulation circuit for electric power transmission which concerns on the 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

<First Embodiment>
[Configuration and basic operation]
FIG. 1 is a diagram showing a configuration of a power conversion device according to the first embodiment of the present invention.

  Referring to FIG. 1, power conversion device 201 includes a power transmission insulating circuit 101 and a rectifying unit 51. The power transmission insulating circuit 101 includes capacitors C <b> 0 to C <b> 2, an input switch unit 21, an output switch unit 22, a control unit 14, and a current detection unit 15. The input switch unit 21 includes switch elements Z1 and Z2. The output switch unit 22 includes switch elements Z3 and Z4.

  The power conversion device 201 converts AC power supplied from the AC power source 301 into DC power and supplies the DC power to the load 302. The load 302 is a main battery for driving, for example, EV and plug-in type HV.

  The rectifying unit 51 includes, for example, a diode bridge, and full-wave rectifies the AC power received from the AC power supply 301 and outputs the rectified current to the power transmission insulating circuit 101.

  In the power transmission insulating circuit 101, the switch element Z1 includes a first end T1 electrically connected to the first end T11 of the capacitor C0 and a second end electrically connected to the first end T13 of the capacitor C1. T2. Switch element Z2 has a first end T3 electrically connected to second end T12 of capacitor C0, and a second end T4 electrically connected to second end T14 of capacitor C1. Switch element Z3 has a first end T5 electrically connected to first end T13 of capacitor C1, and a second end T6 electrically connected to first end T15 of capacitor C2. Switch element Z4 has a first end T7 electrically connected to second end T14 of capacitor C1, and a second end T8 electrically connected to second end T16 of capacitor C2.

  The capacitor C0 stores the power rectified by the rectification unit 51. The input switch unit 21 supplies the power received at the first end T1 of the switch element Z1 and the first end T3 of the switch element Z2, that is, the power stored in the capacitor C0, to the capacitor C1. The output switch unit 22 supplies the power stored in the capacitor C1 to the capacitor C2. The electric power stored in the capacitor C2 is discharged and supplied to the load 302.

  The control unit 14 switches the switching elements Z1 to Z4 on and off by outputting the gate driving signals G1 to G4 to the switching elements Z1 to Z4, respectively. The power transmission insulating circuit 101 transmits the power stored in the capacitor C0 to the load 302 while insulating between the rectifying unit 51 and the load 302 by switch control of the control unit 14.

  Current detector 15 is, for example, a Hall element, and is connected in series with capacitor C1. The current detector 15 measures the capacitor current IC flowing through the capacitor C1, that is, the charging current and discharging current of the capacitor C1.

[Operation]
Next, the operation when the power transmission insulating circuit according to the first embodiment of the present invention performs power transmission and failure detection will be described with reference to the drawings.

  FIG. 2 is a diagram showing a switching operation by the power transmission insulating circuit according to the first embodiment of the present invention.

  With reference to FIG. 2, first, in a period T1, the control unit 14 turns on the switch element Z1, turns on the switch element Z2, turns off the switch element Z3, and turns off the switch element Z4. Thereby, the electric charge stored in the capacitor C0 is discharged, and the discharged electric charge is stored in the capacitor C1. Since the switch elements Z3 and Z4 are turned off, insulation between the rectifying unit 51 and the load 302 is ensured.

  Next, the control unit 14 turns off the switch elements Z1 to Z4 in the period T2. This provides a dead time for ensuring insulation between the input side and the output side of the power transmission insulating circuit 101. That is, it is possible to prevent a short circuit between the input side and the output side of the power transmission insulating circuit 101, that is, between the rectifying unit 51 and the load 302, via each switch in the input switch unit 21 and each switch in the output switch unit 22. it can.

  Next, in the period T3, the control unit 14 turns off the switch element Z1, turns off the switch element Z2, turns on the switch element Z3, and turns on the switch element Z4. Thereby, the electric charge stored in the capacitor C1 is discharged, and the discharged electric charge is stored in the capacitor C2. Since the switch elements Z1 and Z2 are turned off, insulation between the rectifying unit 51 and the load 302 is ensured.

  Next, the control unit 14 turns off the switch elements Z1 to Z4 in the period T4. As a result, similarly to the period T2, a dead time for ensuring insulation between the input side and the output side of the power transmission insulating circuit 101 is provided.

  Here, in the period T <b> 1 to T <b> 4, the capacitor C <b> 1 is charged with power from the rectifying unit 51, and the power stored in the capacitor C <b> 2 is discharged and supplied to the load 302. In the periods T2 and T4, there is no charge movement in the capacitor C1.

  And the control part 14 cooperates with the rectification | straightening part 51 by repeating these periods T1, T2, T3, and T4 in this order, between the input side and output side of the insulating circuit 101 for electric power transmission. The AC power from the AC power supply 301 is converted into DC power and supplied to the load 302 while being insulated.

  FIG. 3 is a diagram showing a power transmission operation by the power transmission insulating circuit according to the first embodiment of the present invention.

  Referring to FIG. 3, in power transmission insulating circuit 101, an operation of charging capacitor C <b> 1 by turning on each switch element in input switch unit 21 and turning off each switch element in output switch unit 22, By alternately turning off each switch element in the input switch unit 21 and turning on each switch element in the output switch unit 22 and discharging the capacitor C1, the input side of the insulating circuit 101 for power transmission And the electric power from AC power supply 301 is transmitted to the load 302, insulating between output sides.

  FIG. 4 is a diagram illustrating a gate drive signal and a capacitor current when it is assumed that the control unit does not perform switch control based on the capacitor current in the power transmission insulating circuit according to the first embodiment of the present invention. is there.

  The waveform of the capacitor current IC with respect to the gate drive signals G1 to G4 is ideally as shown in FIG.

  At timing TA, when the gate drive signals G1 and G2 are set to a logic low level and the switch elements Z1 and Z2 are turned off while the capacitor current IC, that is, the charge current of the capacitor C1 is flowing, the capacitor current IC and the switch element Z1 A large switching loss is generated based on the product of Z2 and the voltage across Z2.

  In addition, at time TB, when the capacitor current IC, that is, the discharge current of the capacitor C1 is flowing, when the gate drive signals G3 and G4 are set to the logic low level and the switch elements Z3 and Z4 are turned off, the capacitor current IC and the switch A large switching loss is generated based on the product of the voltages across the elements Z3 and Z4.

  On the other hand, in the power transmission insulating circuit 101, the control unit 14 determines the timing to turn off the switch element Z1 and the switch element Z2 based on the charging current of the capacitor C1, and the discharge current of the capacitor C1. Then, the operation of determining the timing to turn off the switch element Z3 and the switch element Z4 is performed. The control unit 14 determines these timings based on the measurement result of the capacitor current IC by the current detection unit 15.

  FIG. 5 is a diagram showing a gate drive signal and a capacitor current in the power transmission insulating circuit according to the first embodiment of the present invention.

  Referring to FIG. 5, control unit 14 determines the timing for turning off switching element Z1 and switching element Z2 based on the charging current of capacitor C1 when transitioning from period T1 to period T2, and from period T3. An operation is performed in which the switching element Z3 and the switching element Z4 are turned off based on the discharge current of the capacitor C1 during the transition to the period T4.

  More specifically, the control unit 14 sets the gate drive signals G1 and G2 to a logic low level and turns off the switch elements Z1 and Z2 at the timing TC when the capacitor current IC is substantially zero, that is, when the charging of the capacitor C1 is completed.

  Further, the control unit 14 sets the gate drive signals G3 and G4 to the logic low level and turns off the switch elements Z3 and Z4 at the timing TD when the capacitor current IC is substantially zero, that is, when the discharge of the capacitor C1 is completed.

  By the way, in the insulating circuit for a power supply device described in Patent Document 1, when each switch element in the first switch circuit is turned on, a charging current flows to the second capacitor and electric charge starts to be accumulated. When the switch elements are turned off in a state where the charging current is flowing through the second capacitor, a large switching loss is generated based on the product of the charging current and the voltage across the switch elements.

  As a method of turning off the switch element after the capacitor current IC becomes substantially zero, a method of lowering the frequency of the gate drive signal is conceivable.

  However, in such a method, since the ripple of the output voltage of the power transmission insulating circuit 101 increases due to the decrease in the frequency of the gate drive signal, it is necessary to increase the capacitance of the smoothing capacitor C2, for example. As a result, the size of the capacitor in the power transmission insulating circuit 101 increases and the circuit area increases.

  In addition, since the timing at which the capacitor current IC becomes substantially zero varies depending on the operation state and type of the load 302, the frequency of the gate drive signals G1 to G4 needs to be significantly reduced, or the capacitor current IC is substantially reduced. There is a possibility that the switch element is turned off at a timing that is not zero.

  On the other hand, in the power transmission insulating circuit according to the first embodiment of the present invention, the control unit 14 determines the timing to turn off the switch element Z1 and the switch element Z2 based on the charging current of the capacitor C1. Based on the operation and the discharge current of the capacitor C1, an operation for determining the timing to turn off the switch element Z3 and the switch element Z4 is performed.

  That is, the power transmission insulating circuit 101 constantly monitors the timing when the capacitor current IC becomes substantially zero by the configuration for monitoring the capacitor current IC, and turns off each switch element when the capacitor current IC becomes substantially zero. be able to. This maximizes the driving frequency of each switch element while reducing the switching loss and improving the power efficiency, thereby enabling high-speed operation. Further, it is not necessary to increase the size of the capacitor, and an increase in circuit area can be prevented.

  Therefore, in the power transmission insulating circuit according to the first embodiment of the present invention, switching loss can be reduced in the circuit that transmits power while insulating the input side and the output side.

  Further, in the power transmission insulating circuit according to the first embodiment of the present invention, the current detection unit 15 measures the charging current and discharging current of the capacitor C1. And the control part 14 determines the timing which turns off each switch element based on the measurement result by the electric current detection part 15. FIG.

  Thus, by directly monitoring the current flowing through the capacitor C1, the timing can be obtained more accurately than, for example, a configuration in which the voltage across each capacitor is measured and the timing at which the capacitor current IC becomes substantially zero is calculated. Can do. Moreover, since the said timing can be acquired with a simple process, switch control can be performed rapidly.

  Further, with the configuration in which the current sensor for the capacitor C1 is provided, the timing at which the charging current of the capacitor C1 becomes substantially zero and the timing at which the discharge current of the capacitor C1 becomes substantially zero can be detected by one current sensor.

  Further, in the power transmission insulating circuit according to the first embodiment of the present invention, the control unit 14 sets the timing of turning off the switch element Z1 and the switch element Z2 when the transition from the period T1 to the period T3 is made in the capacitor C1. An operation to be determined based on the charging current and an operation to determine the timing for turning off the switch element Z3 and the switch element Z4 when transitioning from the period T3 to the period T1 based on the discharge current of the capacitor C1 are performed.

  With such a configuration, switching loss can be reduced in the operation of transmitting power while insulating the input side and the output side of the power transmission insulating circuit 101.

  More specifically, in the power transmission insulating circuit according to the first embodiment of the present invention, the control unit 14 sets the timing to turn off the switch element Z1 and the switch element Z2 when transitioning from the period T1 to the period T2. An operation of determining based on the charging current of the capacitor C1 and an operation of determining the timing of turning off the switching element Z3 and the switching element Z4 when transitioning from the period T3 to the period T4 based on the discharging current of the capacitor C1 are performed.

  As described above, by providing the dead time, the insulation between the input side and the output side of the power transmission insulating circuit 101 can be reliably ensured.

  Further, in the power transmission insulating circuit according to the first embodiment of the present invention, the control unit 14 determines the timing for turning off the switch element Z1 and the switch element Z2 based on the charging current of the capacitor C1, and Based on the discharge current of the capacitor C1, both operations for determining the timing for turning off the switch element Z3 and the switch element Z4 are performed.

  As described above, each switch element in the input switch unit 21 is turned off at the timing when the charging current of the capacitor C1 becomes substantially zero, and each switch element in the output switch unit 22 at the timing when the discharge current of the capacitor C1 becomes substantially zero. The switching loss in the power transmission insulating circuit 101 can be greatly reduced by the configuration in which both of the operations for turning off are performed.

  Note that the control unit 14 turns off each switch element in the input switch unit 21 at the timing when the charging current of the capacitor C1 becomes substantially zero, and the output switch unit 22 at the timing when the discharge current of the capacitor C1 becomes almost zero. If the configuration performs at least one of the operations of turning off each switching element, the object of the present invention to reduce switching loss in a circuit that transmits power while insulating the input side and the output side can be achieved. Is possible.

  In the power transmission insulating circuit according to the first embodiment of the present invention, the current sensor for the capacitor C1 is provided. However, the present invention is not limited to this. If current detection accuracy is not a problem, a configuration in which a current sensor for the capacitor C0 and a current sensor for the capacitor C2 may be provided instead of the current sensor for the capacitor C1.

  In the power transmission insulating circuit 101, the power rectified by the rectifying unit 51 is smoothed by the capacitor C0. However, a capacitor for smoothing the power rectified by the rectifying unit 51 is provided in the rectifying unit 51. In such a case, the power transmission insulating circuit 101 can be configured without the capacitor C0. However, the provision of the capacitor C0 provides the effect of preventing the ripple of the input current to the power transmission insulating circuit 101 and stabilizing the circuit operation.

  Further, the power transmission insulating circuit according to the first embodiment of the present invention is configured to include the capacitors C0 to C2, but is not limited to the capacitor and includes other power storage elements such as a coil (inductor). It may be a configuration.

  In the power transmission insulating circuit according to the first embodiment of the present invention, the control unit 14 is configured to repeat the periods T1 to T4. However, the present invention is not limited to this. The periods T2 and T4 do not need to be ideally provided that the control unit 14 may repeat the periods T1 and T3 in order.

  Next, another embodiment of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

<Second Embodiment>
The present embodiment relates to a power transmission insulating circuit in which the method for measuring the capacitor current is changed as compared with the power transmission insulating circuit according to the first embodiment. The contents other than those described below are the same as those of the power transmission insulating circuit according to the first embodiment.

  FIG. 6 is a diagram showing a configuration of an insulating circuit for power transmission according to the second embodiment of the present invention.

  Referring to FIG. 6, power conversion device 202 includes a power transmission insulating circuit 102 and a rectifying unit 51. The power transmission insulating circuit 102 includes output voltage detection units 10, 11, and 12 instead of the current detection unit 15, as compared with the power transmission insulation circuit according to the first embodiment of the present invention.

  The output voltage detector 10 detects the voltage V0 between the first end T1 of the switch element Z1 and the first end T3 of the switch element Z2, that is, the voltage V0 across the capacitor C0. The output voltage detector 11 detects the voltage V1 across the capacitor C1. The output voltage detector 12 detects the voltage V2 across the capacitor C2.

  The control unit 14 detects the voltage V0 across the capacitor C0 detected by the output voltage detection unit 10, the voltage V1 across the capacitor C1 detected by the output voltage detection unit 11, and the capacitor C2 detected by the output voltage detection unit 12. Based on the both-end voltage V2, the timing when the charging current of the capacitor C1 becomes substantially zero and the timing when the discharging current of the capacitor C1 becomes substantially zero are acquired.

  FIG. 7 is a diagram schematically showing the voltage waveform of each capacitor in the power transmission insulating circuit according to the second embodiment of the present invention.

  Referring to FIG. 7, the difference between voltage V0 and voltage V1 becomes small at the end of period T1, which is the timing when the charging current of capacitor C1 becomes substantially zero. Using this, the control unit 14 can acquire the timing at which the charging current of the capacitor C1 becomes substantially zero based on the detection result of the output voltage detection unit 10 and the detection result of the output voltage detection unit 11. is there.

  In addition, the difference between the voltage V1 and the voltage V2 becomes small at the end of the period T3, which is the timing when the discharge current of the capacitor C1 becomes substantially zero. Using this, the control unit 14 can acquire the timing at which the discharge current of the capacitor C1 becomes substantially zero based on the detection result of the output voltage detection unit 11 and the detection result of the output voltage detection unit 12. is there.

  Since other configurations and operations are the same as those of the power transmission insulating circuit according to the first embodiment, detailed description thereof will not be repeated here.

  The above embodiment 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 description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 10, 11, 12 Output voltage detection part 14 Control part 15 Current detection part 21 Input switch part 22 Output switch part 51 Rectification part 101,102 Insulation circuit 201,202 Power converter 301 AC power supply 302 Load C0-C2 Capacitor Z1, Z2, Z3, Z4 switch elements

Claims (6)

A power storage element having a first end and a second end;
A first switch element having a first end and a second end electrically connected to the first end of the electricity storage element, and a first end and electrically connected to the second end of the electricity storage element An input switch unit that includes a second switch element having a second end, and that supplies power received at the first end of the first switch element and the first end of the second switch element to the power storage element When,
A third switch element having a first end and a second end connected to the first end of the power storage element, and a fourth end having a first end and a second end connected to the second end of the power storage element. An output switch unit for outputting the electric power stored in the electric storage element,
A controller for controlling on / off of the first switch element to the fourth switch element,
The controller is configured to determine a timing for turning off the first switch element and the second switch element based on a charging current of the power storage element, and to perform the third operation based on a discharge current of the power storage element. An insulating circuit for power transmission that performs at least one of operations for determining a timing to turn off a switch element and the fourth switch element. The power transmission insulating circuit further includes:
A current detection unit for measuring a charging current and a discharging current of the storage element;
The said control part is an insulation circuit for electric power transmission of Claim 1 which determines the said timing based on the measurement result by the said electric current detection part. The control unit turns on the switch elements in the input switch unit and turns off the switch elements in the output switch unit; and turns off the switch elements in the input switch unit; And a second period of turning on each of the switch elements in the output switch section in order,
The control unit determines a timing for turning off the first switch element and the second switch element based on a charging current of the power storage element when transitioning from the first period to the second period. An operation and an operation for determining a timing for turning off the third switch element and the fourth switch element based on a discharge current of the power storage element when the second period transits to the first period. The insulating circuit for power transmission according to claim 1 or 2, wherein at least one of them is performed. The control unit includes the first period, a third period in which the switch elements in the input switch unit and the switch elements in the output switch unit are turned off, the second period, and the input switch. And the fourth period of turning off each switch element in the output switch section and the switch element in the output switch section in this order,
The control unit determines a timing to turn off the first switch element and the second switch element based on a charging current of the power storage element when transitioning from the first period to the third period. An operation, and an operation for determining a timing for turning off the third switch element and the fourth switch element based on a discharge current of the power storage element when the second period transits to the fourth period. The insulating circuit for power transmission according to claim 3, wherein at least one of them is performed.   The controller is configured to determine a timing for turning off the first switch element and the second switch element based on a charging current of the power storage element, and to perform the third operation based on a discharge current of the power storage element. 5. The power transmission insulating circuit according to claim 1, wherein both an operation for determining a timing for turning off the switch element and the fourth switch element are performed. A power conversion device for converting AC power to DC power and supplying it to a load,
A rectifying unit for rectifying the received AC power;
A power transmission insulating circuit for transmitting the power rectified by the rectifying unit to the load while insulating between the rectifying unit and the load;
The power transmission insulating circuit is:
A power storage element having a first end and a second end;
A first switch element connected between the rectification unit and the first end of the electricity storage element; and a second switch element connected between the rectification unit and the second end of the electricity storage element; An input switch unit for supplying the electricity rectified by the rectification unit to the storage element;
A third switch element having a first end and a second end connected to the first end of the power storage element, and a fourth end having a first end and a second end connected to the second end of the power storage element. An output switch unit for outputting the electric power stored in the electric storage element,
A controller for controlling on / off of the first switch element to the fourth switch element,
The controller is configured to determine a timing for turning off the first switch element and the second switch element based on a charging current of the power storage element, and to perform the third operation based on a discharge current of the power storage element. A power converter that performs at least one of operations for determining a timing for turning off a switch element and the fourth switch element.

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