JP2012019677A - Electric power transmitting insulator circuit, and electric power converting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability by detecting failures of a switch element with an inexpensive structure, in a circuit transmitting electric power while insulating an input side and an output side.SOLUTION: An electric power transmitting insulator circuit 101 comprises an input switch portion 21 including switches Z1 and Z2, and supplying electric power received at a first end T1 of the switch Z1 and a first end T3 of the switch Z2 to a first storage element C1; an output switch portion 22 including switches Z3 and Z4, and supplying the electric power stored in the first storage element C1 to a second storage element C2; and a control portion 14 detecting failures of the first switch element Z1 or the forth switch element Z4 on the basis of the both end voltage of the first storage element C1 detected by a first voltage detecting portion 11 and the both end voltage of the second storage element C2 detecting by a second voltage detecting portion 12.

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 positive side and a negative 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 insulation circuit for a power supply device described in Patent Document 1, when a switch element in each switch circuit fails and is short-circuited, there is a possibility that insulation between the input side and the output side cannot be ensured. However, Patent Document 1 does not disclose a configuration for dealing with such a problem.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to detect a failure of a switch element with a low-cost configuration in a circuit that transmits power while insulating the input side and the output side. Accordingly, it is an object to provide an insulating circuit for power transmission and a power conversion device capable of improving the reliability of the circuit.

  In order to solve the above-described problem, an insulating circuit for power transmission according to an aspect of the present invention includes a first power storage element having a first end and a second end, and a second power having a first end and a second end. A first switch element having a power storage element, a first end, and a second end electrically connected to the first end of the first power storage element; a first end; and the first power storage element. A second switch element having a second end electrically connected to the second end, wherein the power received at the first end of the first switch element and the first end of the second switch element is An input switch unit for supplying to the first power storage element; a third switch element connected between a first end of the first power storage element and a first end of the second power storage element; and Connected between the second end of the first power storage element and the second end of the second power storage element. An output switch unit for supplying power stored in the first power storage element to the second power storage element, and for detecting a voltage across the first power storage element. First voltage detection unit, a second voltage detection unit for detecting a voltage across the second power storage element, and both ends of the first power storage element detected by the first voltage detection unit A control unit for detecting a failure of the first switch element to the fourth switch element based on the voltage and the voltage across the second power storage element detected by the second voltage detection unit; And the controller detects a failure of the third switch element and the fourth switch element based on a difference between the voltage across the first power storage element and the voltage across the second power storage element. To do.

  With such a configuration, it is possible to prevent a malfunction due to a short circuit between the input side and the output side of the power transmission insulating circuit by detecting a short circuit failure of each switch element and taking necessary measures by the user or the like. . In addition, since the voltage across the storage element having a higher level than the voltage across the switch element is monitored, it is possible to use an inexpensive photocoupler or the like in the output voltage detection unit, thereby reducing the cost. . Therefore, in a circuit that transmits power while insulating between the input side and the output side, the reliability of the circuit can be improved by detecting a failure of the switch element with a low-cost configuration. Furthermore, even when the voltage across the power storage element varies depending on time when the switch element is normal and when a short circuit failure occurs, the failure of the switch element can be detected with high accuracy.

  Preferably, the control unit selects any one of the first switch element to the fourth switch element as a failure detection target switch element, and the input switch unit including the failure detection target switch element or The other switch element in the output switch unit is turned on, and the failure detection target switch element and the switch elements in the input switch unit or the output switch unit that do not include the failure detection target switch element are turned off. In the state, when the failure detection target switch element is included in the input switch unit, a failure of the failure detection target switch element is detected based on a voltage across the first power storage element, and the failure detection target switch element Is included in the output switch section, it is based on the voltage across the second storage element. Te detecting a failure of the fault detection object switching element.

  With such a configuration, even when the failure detection target switch element is short-circuited, it is possible to prevent a short circuit between the input side and the output side of the power transmission insulating circuit during the failure detection period.

  Preferably, the control unit includes a voltage across the first power storage element and a voltage across the second power storage element in a state where at least one of the third switch element and the fourth switch element is turned off, or The difference between the voltages at both ends is stored as an initial value, and the first power storage element newly detected in a state in which at least one of the initial value and the third switch element and the fourth switch element is turned off And a difference between both end voltages of the second power storage element are detected, and a failure of the third switch element and the fourth switch element is detected based on the comparison result.

  With such a configuration, the failure determination criterion can be adjusted according to the characteristic variation of the output voltage detection unit. Therefore, it is possible to prevent the failure detection accuracy from being deteriorated due to the characteristic variation of the output voltage detection unit. .

  Preferably, the power transmission insulating circuit further includes a third voltage for detecting an input voltage which is a voltage between the first end of the first switch element and the first end of the second switch element. A detection unit is provided, and the control unit detects a failure of the first switch element and the second switch element based on a difference between the voltage across the first power storage element and the input voltage.

  With such a configuration, it is possible to detect a failure of the switch element with high accuracy even when the voltage across the power storage element varies depending on time when the switch element is normal and when a short circuit failure occurs.

  More preferably, the control unit is configured to control the input voltage and the both-end voltage of the first power storage element in the state where at least one of the first switch element and the second switch element is turned off, or each of the both-end voltages. The difference is stored as an initial value, and the initial value, the input voltage newly detected in a state where at least one of the first switch element and the second switch element is turned off, and the first power storage element The voltage difference between both ends is compared, and a failure of the first switch element and the second switch element is detected based on the comparison result.

  With such a configuration, the failure determination criterion can be adjusted according to the characteristic variation of the output voltage detection unit. Therefore, it is possible to prevent the failure detection accuracy from being deteriorated due to the characteristic variation of the output voltage detection unit. .

  More preferably, the control unit detects a failure of the third switch element and the fourth switch element based on a difference between a voltage across the first power storage element and a voltage across the second power storage element. And 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 the switch elements in the input switch unit and A second period for turning off the switch elements in the output switch unit; a third period for turning off the switch elements in the input switch unit; and turning on the switch elements in the output switch unit; A fourth period in which each switch element in the input switch unit and each switch element in the output switch unit are turned off In this order, the control unit detects a failure of the third switch element and the fourth switch element in the second period, and detects the first switch element and the fourth switch element in the fourth period. A failure of the second switch element is detected.

  As described above, the failure detection of the switch element can be detected with high accuracy by the configuration in which the failure detection is performed in the second period and the fourth period in which the voltage difference between the power storage elements becomes large.

  Preferably, the power transmission insulating circuit has a normal operation mode and a failure detection mode, and the control unit turns on the switch elements in the input switch unit in the normal operation mode, and the output switch A first period in which each switch element in the unit is turned off and a second period in which each switch element in the input switch unit is turned off and each switch element in the output switch unit is turned on are sequentially repeated. The control unit executes the first period and the second period in the failure detection mode, and sets the first period and the second period longer than the normal operation mode, respectively. .

  With such a configuration, the two storage elements to be measured can be sufficiently charged / discharged to increase the difference between the voltages at both ends, so that the switching frequency of the input switch unit and the output switch unit in the power transmission insulating circuit is high. Even in this case, the failure detection accuracy can be increased.

  Preferably, the control unit outputs a control signal to the first switch element to the fourth switch element, respectively, while insulating between itself and the first switch element to the fourth switch element. Thus, switching of the first switch element to the fourth switch element is controlled.

  With such a configuration, the switching control of the first switch element to the fourth switch element can be stably performed.

  More preferably, the control unit includes a plurality of photocouplers provided corresponding to each of the first switch element to the fourth switch element, and outputs the control signal via the corresponding photocoupler. Output to the first switch element to the fourth switch element, respectively.

  Since the photocoupler can stably transmit the signal regardless of the duty ratio of the control signal, the degree of freedom in selecting the input / output voltage of the power converter is increased as compared with the configuration using the pulse transformer. be able to. In addition, even when a failure detection mode in which the charge / discharge time of the first power storage element and the second power storage element is extended is provided, the power transmission insulating circuit can be downsized as compared with the configuration using the pulse transformer. .

  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 turn-off and the second period of turning on each of the switch elements in the output switch unit in order, and the control unit causes a failure of the first switch element to the fourth switch element at a predetermined timing. It is possible to detect the failure of the first switch element to the fourth switch element at a timing based on a command from the outside of the power transmission insulating circuit.

  With such a configuration, it is possible to flexibly respond to various requests from users.

  Preferably, the power transmission insulating circuit further includes a third power storage element connected between the first end of the first switch element and the first end of the second switch element.

  With such a configuration, it is possible to prevent the ripple of the input current to the power transmission insulating circuit and to stabilize the circuit operation.

  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 first power storage element having a first end and a second end, a second power storage element having a first end and a second end, and between the rectifying unit and the first end of the first power storage element The first switch element connected and the second switch element connected between the rectifier and the second end of the first power storage element, and the electric power rectified by the rectifier is the first An input switch unit for supplying power to the storage element A third switch element connected between a first end of the first power storage element and a first end of the second power storage element; a second end of the first power storage element; and the second power storage. An output switch unit including a fourth switch element connected between the second end of the element and supplying power stored in the first power storage element to the second power storage element; A first voltage detection unit for detecting a voltage across one storage element, a second voltage detection unit for detecting a voltage across the second storage element, and the first voltage detection unit. Based on the detected voltage across the first power storage element and the voltage across the second power storage element detected by the second voltage detector, the first switch element through the fourth switch A control unit for detecting a failure of the element, the control unit, Detecting a failure of the third switching element and the fourth switching element on the basis of the difference between the serial voltage across the voltage across the second storage element of the first power storage device.

  With such a configuration, it is possible to prevent a malfunction due to a short circuit between the input side and the output side of the power transmission insulating circuit by detecting a short circuit failure of each switch element and taking necessary measures by the user or the like. . In addition, since the voltage across the storage element having a higher level than the voltage across the switch element is monitored, an inexpensive photocoupler can be used in the output voltage detection unit, and the cost can be reduced. Therefore, in a circuit that transmits power while insulating between the input side and the output side, the reliability of the circuit can be improved by detecting a failure of the switch element with a low-cost configuration. Furthermore, even when the voltage across the power storage element varies depending on time when the switch element is normal and when a short circuit failure occurs, the failure of the switch element can be detected with high accuracy.

  According to the present invention, in a circuit that transmits power while insulating the input side and the output side, the reliability of the circuit can be improved by detecting a failure of the switch element with a low-cost configuration.

It is a figure which shows the structure of the power converter device which concerns on embodiment of this invention. It is a figure which shows the structure of the output voltage detection part in the insulation circuit for electric power transmission which concerns on embodiment of this invention. It is a figure which shows the switching operation | movement by the insulated circuit for electric power transmission which concerns on embodiment of this invention. It is a figure which shows roughly the voltage waveform of each capacitor in the insulated circuit for electric power transmission which concerns on embodiment of this invention. It is a figure which shows an example of a structure of the control part in the insulation circuit for electric power transmission which concerns on embodiment of this invention. It is a figure which shows an example of a structure of the control part in the insulation circuit for electric power transmission which concerns on 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.

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

  Referring to FIG. 1, power conversion device 201 includes a power transmission insulating circuit 101 and a rectifying unit 102. 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, output voltage detection units 10 to 12, and a control unit 14. The input switch unit 21 includes switch elements Z1 and Z2. The output switch unit 22 includes switch elements Z3 and Z4.

  The power converter 201 converts AC power supplied from the AC power source 202 into DC power and supplies the DC power to the load 203. The load 203 is a main battery for driving such as EV and plug-in type HV, for example.

  The rectifying unit 102 includes, for example, a diode bridge, and full-wave rectifies the AC power received from the AC power source 202 and outputs the rectified power 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 rectifying unit 102. 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 203.

  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 203 while insulating between the rectifying unit 102 and the load 203 by switch control of the control unit 14.

  The output voltage detector 10 detects the voltage V0 between the first terminal T1 of the switch element Z1 and the first terminal T3 of the switch element Z2, that is, the voltage (input 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, a failure of the switch element Z1 to the switch element Z4 is detected.

  FIG. 2 is a diagram showing a configuration of an output voltage detection unit in the power transmission insulating circuit according to the embodiment of the present invention. FIG. 2 representatively shows the configuration of the output voltage detection unit 10. The configuration of the output voltage detectors 11 and 12 is the same as that of the output voltage detector 10.

  Referring to FIG. 2, output voltage detection unit 10 includes a photocoupler X1, an input resistor R1, and an output resistor R2. Between the first end T11 and the second end T12 of the capacitor C0, the input resistor R1 and the light emitting element of the photocoupler X1 are connected in series. The light receiving element of the photocoupler X1 and the output resistor R2 are connected in series between the node supplied with the power supply voltage Vdd and the node supplied with the ground voltage.

  An amount of current corresponding to the voltage across the capacitor C0 flows through the light emitting element of the photocoupler X1, and this amount of current is transmitted to the light receiving element of the photocoupler X1. That is, an amount of current corresponding to the voltage across the capacitor C0 flows through the light receiving element in the photocoupler X1. Thus, a voltage having a magnitude corresponding to the voltage across the capacitor C0 is transmitted to the control unit 14.

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

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

  Referring to FIG. 3, first, in the 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 102 and the load 203 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 102 and the load 203, 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 102 and the load 203 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 the electric power from the rectifying unit 102, and the electric power stored in the capacitor C <b> 2 is discharged and supplied to the load 203. In the periods T2 and T4, there is no charge movement in the capacitor C1.

  And the control part 14 cooperates with the rectifier 102 by repeating these periods T1, T2, T3, and T4 in this order, and between the input side and the output side of the insulation circuit 101 for electric power transmission. While insulating, the AC power from the AC power source 202 is converted into DC power and supplied to the load 203.

  Furthermore, the control unit 14 provides failure detection periods TE1 to TE4 for detecting failures of the switch elements Z1 to Z4, respectively. The failure detection periods TE1 to TE4 may be provided between the periods T1 to T4, or may be provided in the periods T1 to T4.

  Specifically, the control unit 14 selects any one of the switch elements Z1 to Z4 as the failure detection target switch element. The control unit 14 turns on the other switch element in the input switch unit 21 or the output switch unit 22 including the failure detection target switch element. Then, the control unit 14 turns off the failure detection target switch element and each switch element in the input switch unit 21 or the output switch unit 22 that does not include the failure detection target switch element.

  In this state, when the failure detection target switch element is included in the input switch unit 21, the control unit 14 detects a failure of the failure detection target switch element based on the voltage V0 across the capacitor C0 and the voltage V1 across the capacitor C1. To do. In addition, when the failure detection target switch element is included in the output switch unit 22, the control unit 14 detects a failure of the failure detection target switch element based on the voltage V1 across the capacitor C1 and the voltage V2 across the capacitor C2.

  More specifically, in the period TE1, the control unit 14 turns off the switch element Z1, turns on the switch element Z2, turns off the switch element Z3, and turns off the switch element Z4. Then, the control unit 14 detects a failure of the switch element Z1 based on the difference between the voltage V1 and the voltage V0 in this state. Specifically, when the switch element Z1 is normal, the voltage V0 is higher than the voltage V1. This is because in the period TE1, the capacitor C0 is charged by the electric power from the rectifying unit 102, while the charge stored in the capacitor C0 is not discharged and the capacitor C1 is not charged. On the other hand, when the switch element Z1 fails and is short-circuited, the voltage V1 and the voltage V0 are equalized by the short-circuited switch element Z1 and the on-state switch element Z2. The control unit 14 detects a failure of the switch element Z1 based on the difference in voltage difference between the voltage V0 and the voltage V1.

  In the period TE2, the control unit 14 turns on the switch element Z1, turns off the switch element Z2, turns off the switch element Z3, and turns off the switch element Z4. Then, the control unit 14 detects a failure of the switch element Z2 based on the difference between the voltage V1 and the voltage V0 in this state. Specifically, when the switch element Z2 is normal, the voltage V0 is higher than the voltage V1. This is because, during the period TE2, the capacitor C0 is charged by the power from the rectifying unit 102, while the charge stored in the capacitor C0 is not discharged and the capacitor C1 is not charged. On the other hand, when the switch element Z2 is faulty and short-circuited, the voltage V1 and the voltage V0 are equalized by the short-circuited switch element Z2 and the on-state switch element Z1. The control unit 14 detects a failure of the switch element Z2 based on the difference in voltage difference between the voltage V0 and the voltage V1.

  In the period TE3, the control unit 14 turns off the switch element Z1, turns off the switch element Z2, turns off the switch element Z3, and turns on the switch element Z4. Then, the control unit 14 detects a failure of the switch element Z3 based on the difference between the voltage V1 and the voltage V2 in this state. Specifically, when the switch element Z3 is normal, the voltage V1 is higher than the voltage V2. This is because in the period TE3, the charge stored in the capacitor C1 is not discharged, while the charge stored in the capacitor C2 is discharged to the load 203. On the other hand, when the switch element Z3 fails and is short-circuited, the voltage V1 and the voltage V2 are equalized by the short-circuited switch element Z3 and the on-state switch element Z4. The control unit 14 detects a failure of the switch element Z3 based on the difference in voltage difference between the voltage V1 and the voltage V2.

  In the period TE4, the control unit 14 turns off the switch element Z1, turns off the switch element Z2, turns on the switch element Z3, and turns off the switch element Z4. Then, the control unit 14 detects a failure of the switch element Z4 based on the difference between the voltage V1 and the voltage V2 in this state. Specifically, when the switch element Z4 is normal, the voltage V1 is higher than the voltage V2. This is because, during the period TE4, the charge stored in the capacitor C1 is not discharged, while the charge stored in the capacitor C2 is discharged to the load 203. On the other hand, when the switch element Z4 fails and is short-circuited, the voltage V1 and the voltage V2 are equalized by the short-circuited switch element Z4 and the on-state switch element Z3. The control unit 14 detects a failure of the switch element Z4 based on the difference in voltage difference between the voltage V1 and the voltage V2.

  FIG. 4 is a diagram schematically showing voltage waveforms of the capacitors in the power transmission insulating circuit according to the embodiment of the present invention.

  Referring to FIG. 4, in period T2, the difference between voltage V1 and voltage V2 is greater than in other periods. For this reason, the control part 14 provides the periods TE3 and TE4 in the period T2, for example. With such a configuration, the failure of the switch elements Z3 and Z4 can be detected with high accuracy.

  Here, at the time TA immediately before the end of the period T2, that is, at a timing TA from a predetermined time before the end timing of the period T2 to the end timing of the period T2, the voltage V1 is increasing and the voltage V2 is decreasing. The difference in voltage V2 is maximized. Therefore, control unit 14 provides periods TE3 and TE4 at timing TA, for example. With such a configuration, the failure of the switch elements Z3 and Z4 can be detected with higher accuracy.

  Further, in the period T4, the difference between the voltage V0 and the voltage V1 is larger than in other periods. For this reason, the control part 14 provides the periods TE1 and TE2 in the period T4, for example. With such a configuration, the failure of the switch elements Z1 and Z2 can be detected with high accuracy.

  Here, at the start of the period T4, that is, at the timing TB after a predetermined time from the start timing of the period T4, the voltage V0 is in the rising direction and the voltage V1 is in the decreasing direction, and the difference between the voltage V0 and the voltage V1 is the maximum. Become. For this reason, the control part 14 provides the periods TE1 and TE2 at timing TB, for example. With such a configuration, the failure of the switch elements Z1 and Z2 can be detected with higher accuracy.

  Moreover, in the power converter device which concerns on embodiment of this invention, in the output voltage detection parts 10-12, the photocoupler is used for cost reduction. In general, a photocoupler has a large variation in characteristics. And since the voltage difference of the voltage V0, the voltage V1, and the voltage V2 does not become so large, failure detection accuracy may deteriorate by the characteristic variation of a photocoupler.

  Therefore, in the power conversion device according to the embodiment of the present invention, control unit 14 measures in advance voltage V0, voltage V1, and voltage V2 when each switch element is in a normal state. For example, these voltage values are used as initial values. Save it.

  Specifically, in the periods TE3 and TE4, the difference between the stored voltage V2 and voltage V1 is treated as an initial value in a normal state in which the switch element Z3 or Z4 has not failed, and this initial value and a new measurement are obtained. The difference between the voltage V2 and the voltage V1 is compared, and failure detection of the failure switch element Z3 or Z4 is performed based on the comparison result. That is, the control unit 14 stores the voltage between both ends of the capacitor C1 and the voltage between both ends of the capacitor C2 in the state where at least one of the switch element Z3 and the switch element Z4 is turned off, or the difference between the voltages between both ends as an initial value. Then, the control unit 14 compares the initial value with the difference between the both-end voltage of the capacitor C1 and the both-end voltage of the capacitor C2 newly detected in a state where at least one of the switch element Z3 and the switch element Z4 is turned off. A failure of the switch element Z3 and the switch element Z4 is detected based on the comparison result. For example, the control unit 14 determines that the switch element Z3 and the switch element Z4 are normal if the difference between the voltage across the capacitor C1 and the voltage across the capacitor C2 is within a range of plus or minus several millivolts from the initial value. If it is out of the range, it is determined that the switch element Z3 and the switch element Z4 are abnormal.

  In the periods TE1 and TE2, the difference between the stored voltage V0 and the voltage V1 is treated as an initial value in a normal state in which the switch element Z1 or Z2 has not failed, and this initial value and the newly measured voltage V0. And the difference between the voltage V1 and the failure detection of the failure switch element Z1 or Z2 is performed based on the comparison result. That is, the control unit 14 stores the voltage between both ends of the capacitor C0 and the voltage between both ends of the capacitor C1 in the state where at least one of the switch element Z1 and the switch element Z2 is turned off, or the difference between the voltages between both ends as an initial value. Then, the control unit 14 compares the initial value with the difference between the both-end voltage of the capacitor C0 and the both-end voltage of the capacitor C1 newly detected in a state where at least one of the switch element Z1 and the switch element Z2 is turned off. A failure of the switch element Z1 and the switch element Z2 is detected based on the comparison result.

  When the voltage across the two capacitors is stored as the initial value, the difference between these initial values is calculated when a failure is detected, and the difference between the calculated difference and the voltage across the two newly detected capacitors is calculated. Compare with the difference.

  With such a configuration, it is possible to adjust the failure determination reference according to the characteristic variation of the photocoupler, so that it is possible to prevent the failure detection accuracy from being deteriorated due to the characteristic variation of the photocoupler.

  Further, the switch element failure detection processing may be performed in the normal operation mode in which the periods T1 to T4 are repeated as described above, but the failure detection mode in which the charge / discharge time of the capacitor, that is, the period T1 or the period T3 is extended. The failure detection process may be performed in the failure detection mode. That is, in the failure detection mode, the control unit 14 sets the periods T1 and T3 to be longer than those in the normal operation mode, and sets the periods TE1 to TE4 for detecting the failure of the switch elements Z1 to Z4 to the period T1. To each period of the period T4 and at least one timing in the period T1 to the period T4.

  As a result, the two capacitors to be measured can be sufficiently charged / discharged to increase the difference between the voltages at both ends, so that the switching frequency of the input switch unit 21 and the output switch unit 22 in the power transmission insulating circuit 101 is high. However, the failure detection accuracy can be increased.

  The failure detection mode may be automatically executed by the control unit 14 during the normal operation mode, or may be executed at an arbitrary timing by the user. That is, the control unit 14 can detect a failure of the switch element Z1 to the switch element Z4 at a predetermined timing in at least one of the periods T1 to T4 during the periods T1 to T4. Is possible. Further, the control unit 14 can receive a command timing from the outside of the power transmission insulating circuit 101, and can detect a failure of the switch element Z1 to the switch element Z4 at the command timing.

  With such a configuration, it is possible to flexibly respond to various requests from users.

  Here, since the reference potentials of the switch elements Z1, Z2, Z3, and Z4 are different, if a control signal having a common potential is supplied from the control unit 14, each switch element may not perform a desired operation. Such a problem is preferably solved particularly in a power conversion device that inputs and outputs relatively large power, for example, a power conversion device that charges a driving main battery such as an EV and a plug-in type HV.

  Therefore, in the power transmission insulating circuit according to the embodiment of the present invention, the control signal is transmitted while electrically insulating between the control unit 14 and the switch elements Z1, Z2, Z3, and Z4. That is, the control unit 14 outputs a control signal to the switch elements Z1, Z2, Z3, and Z4 while insulating the self and the switch elements Z1, Z2, Z3, and Z4. , Z3 and Z4 are controlled.

  With such a configuration, switching control of the switching elements Z1, Z2, Z3, Z4 can be stably performed.

  FIG. 5 is a diagram illustrating an example of a configuration of a control unit in the power transmission insulating circuit according to the embodiment of the present invention.

  Referring to FIG. 5, control unit 14 includes a signal source 31 and a pulse transformer 32. In the control unit 14, for example, four sets of signal sources 31 and pulse transformers 32 are provided corresponding to the switch elements Z1 to Z4. Hereinafter, each of the switch elements Z1, Z2, Z3, and Z4 may be referred to as a switch element Z. The switch element Z is, for example, an IGBT (Insulated Gate Bipolar Transistor).

  The control unit 14 includes a plurality of pulse transformers 32 provided corresponding to each of the switch elements Z1, Z2, Z3, Z4, and the control signal is transmitted to the switch elements Z1, Z2, Z3, via the corresponding pulse transformer 32. Output to Z4.

  In the control unit 14, the signal source 31 generates a control signal for output to the switch element Z and outputs the control signal to the pulse transformer 32.

  The pulse transformer 32 transmits the control signal received from the signal source 31 to the gate of the switch element Z via the gate resistor R while insulating between the signal source 31 and the switch element Z.

  Here, for example, a signal conversion circuit (not shown) is provided between the signal source 31 and the pulse transformer 32 and between the pulse transformer 32 and the switch element Z.

  Thus, in the power transmission insulating circuit 101, it is possible to use a pulse transformer as an insulating transmission means for the control signal. However, when the failure detection mode in which the charge / discharge time of the capacitor, that is, the period T1 or the period T3 is extended as described above, the switching frequency of the switch element Z1 to the switch element Z4 is lowered, and therefore a pulse transformer is used. That is not preferable.

  This is because when the pulse transformer is used at a low frequency, a large inductance is required, resulting in an increase in the number of turns of the pulse transformer and an increase in volume.

  In the pulse transformer, as the duty ratio of the control signal goes away from 50%, the balance between the primary and secondary magnetic fluxes becomes worse, and the core may be saturated. This makes it difficult to design the pulse transformer itself, and may limit the selection of input / output voltages of the power converter 201.

  FIG. 6 is a diagram illustrating an example of a configuration of a control unit in the power transmission insulating circuit according to the embodiment of the present invention.

  Referring to FIG. 6, control unit 14 includes a signal source 31 and a photocoupler 33. In the control unit 14, for example, four sets of signal sources 31 and photocouplers 33 are provided corresponding to the switch elements Z1 to Z4.

  The control unit 14 includes a plurality of photocouplers 33 provided corresponding to each of the switch elements Z1, Z2, Z3, and Z4, and sends a control signal to the switch elements Z1, Z2, Z3, and the like via the corresponding photocouplers 33. Output to Z4.

  In the control unit 14, the signal source 31 generates a control signal for output to the switch element Z and outputs the control signal to the photocoupler 33.

  The photocoupler 33 transmits the control signal received from the signal source 31 to the gate of the switch element Z via the gate resistor R while insulating between the signal source 31 and the switch element Z.

  More specifically, an amount of current corresponding to the control signal output from the signal source 31 flows through the light emitting element of the photocoupler 33, and this amount of current is transmitted to the light receiving element of the photocoupler 33. That is, an amount of current corresponding to the control signal output from the signal source 31 flows through the light receiving element in the photocoupler 33. As a result, a voltage having a magnitude corresponding to the level of the control signal is transmitted to the gate of the switch element Z while insulating between the signal source 31 and the switch element Z.

  Further, for example, a signal conversion circuit (not shown) is provided between the signal source 31 and the photocoupler 33 and between the photocoupler 33 and the switch element Z.

  Here, the photocoupler can transmit a wide range of frequency signals, and unlike a pulse transformer, there is no demerit such as an increase in volume even for low frequency signals. Therefore, in the power transmission insulating circuit according to the embodiment of the present invention, the pulse transformer is used even in the case of providing the failure detection mode in which the charge / discharge time of the capacitor is extended by the configuration in which the control signal is transmitted using the photocoupler. Compared with the configuration, the power transmission insulating circuit 101 can be downsized.

  Further, since the photocoupler can stably transmit a signal regardless of the duty ratio of the control signal, the degree of freedom in selecting the input / output voltage of the power converter 201 can be increased.

  By the way, the insulation circuit for a power supply device described in Patent Document 1 has a configuration for dealing with the problem that insulation between the input side and the output side cannot be ensured when a switch element in each switch circuit fails and is short-circuited. Not prepared.

  On the other hand, in the power transmission isolation circuit according to the embodiment of the present invention, the control unit 14 is detected by the output voltage detection unit 11 and the voltage V0 across the capacitor C0 detected by the output voltage detection unit 10. Based on the voltage V1 across the capacitor C1 and the voltage V2 across the capacitor C2 detected by the output voltage detector 12, a failure of the switch element Z1 through the switch element Z4 is detected.

  With such a configuration, it is possible to prevent a malfunction due to a short circuit between the input side and the output side of the insulating circuit 101 for power transmission by detecting a short circuit failure of each switch element and taking necessary measures. Become.

  Here, as a configuration for detecting a failure of the switch elements Z1 to Z4, a configuration for monitoring the voltage between both ends of each switch element is conceivable. However, normally, the voltage across the switching elements Z1 to Z4 has a low level, and it is necessary to use expensive parts such as a photorelay, which increases the cost.

  On the other hand, the power transmission insulating circuit according to the embodiment of the present invention is configured to monitor the voltage across the capacitor having a higher level than the voltage across the switch element. For this reason, it is possible to use an inexpensive photocoupler in the output voltage detection units 10 to 12, and it is possible to reduce the cost.

  Therefore, in the power transmission isolation circuit according to the embodiment of the present invention, in the circuit that transmits power while insulating the input side and the output side, the circuit is detected by detecting a failure of the switch element with a low-cost configuration. Reliability can be improved.

  In the power transmission insulating circuit according to the embodiment of the present invention, the control unit 14 selects any one of the switch elements Z1 to Z4 as the failure detection target switch element. The control unit 14 turns on the other switch element in the input switch unit 21 or the output switch unit 22 including the failure detection target switch element. The control unit 14 turns off the failure detection target switch element and each switch element in the input switch unit 21 or the output switch unit 22 that does not include the failure detection target switch element. And the control part 14 detects a failure of the failure detection object switch element based on the both-ends voltage of the capacitor detected in this state. With such a configuration, even when the failure detection target switch element is short-circuited, it is possible to prevent a short circuit between the input side and the output side of the power transmission insulating circuit 101 during the failure detection period. .

  In the power transmission insulating circuit according to the embodiment of the present invention, the control unit 14 causes the failure of the switch element Z3 and the switch element Z4 based on the difference between the voltage V1 across the capacitor C1 and the voltage V2 across the capacitor C2. Is detected. Further, the control unit 14 detects a failure of the switch element Z1 and the switch element Z2 based on a difference between the voltage V1 across the capacitor C1 and the voltage V0 across the capacitor C0. With such a configuration, it is possible to detect a failure of the switch element with high accuracy even when the voltage across the capacitor varies depending on time when the switch element is normal and when a short circuit failure occurs.

  In the power transmission insulating circuit according to the embodiment of the present invention, the control unit 14 is configured to detect the failure of the switch element based on the difference between the voltages at both ends of the two capacitors. Not what you want. When the time transition of the power consumption of the load 203 is known in advance or the like, when the voltage across the capacitor can be accurately grasped when the switch element is normal and at the time of a short circuit failure, the control unit 14 can A configuration in which a failure of the switch element is detected based on the voltage across the two terminals may be employed. In this case, when the failure detection target switch element is included in the input switch unit 21, the control unit 14 detects a failure of the failure detection target switch element based on the voltage V1 across the capacitor C1, and the failure detection target switch element is detected. When included in the output switch unit 22, the failure of the failure detection target switch element is detected based on the voltage V2 across the capacitor C2.

  Further, the power rectified by the rectifying unit 102 is smoothed by the capacitor C0. However, when the capacitor for smoothing the power rectified by the rectifying unit 102 is provided in the rectifying unit 102, the power transmission A configuration in which the capacitor C0 is not provided in the insulating circuit 101 is possible. 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.

  In addition, the power transmission insulating circuit according to the embodiment of the present invention is configured to include the capacitors C0 to C2, but is not limited to the capacitor, and is configured to include other power storage elements such as a coil (inductor). May be.

  Further, in the power transmission insulating circuit according to the 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.

  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 10-12 Output voltage detection part 14 Control part 21 Input switch part 22 Output switch part 31 Signal source 32 Pulse transformer 33 Photocoupler 101 Insulation circuit for electric power transmission 102 Rectification part 201 Power converter 202 AC power supply 203 Load C0-C2 Capacitor X1 Photocoupler R Gate resistance R1 Input resistance R2 Output resistance Z1, Z2, Z3, Z4 Switch element

Claims (11)

A first power storage element having a first end and a second end;
A second 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 first power storage element; a first end; and a second end of the first power storage element; A second switch element having a second end electrically connected thereto, wherein the first power storage receives power received at the first end of the first switch element and the first end of the second switch element. An input switch unit for supplying to the element;
A third switch element connected between a first end of the first power storage element and a first end of the second power storage element, and a second end of the first power storage element and the second power storage An output switch unit including a fourth switch element connected between the second end of the element and supplying power stored in the first power storage element to the second power storage element;
A first voltage detector for detecting a voltage across the first power storage element;
A second voltage detector for detecting a voltage across the second power storage element;
Based on the voltage across the first power storage element detected by the first voltage detector and the voltage across the second power storage element detected by the second voltage detector, the first voltage detector And a control unit for detecting a failure of the switch element or the fourth switch element.   The control unit selects any one of the first switch element to the fourth switch element as a failure detection target switch element, and the input switch unit or the output switch includes the failure detection target switch element. In the state of turning on the other switch element in the part, turning off the failure detection target switch element and each switch element in the input switch part or the output switch part that does not include the failure detection target switch element, When the failure detection target switch element is included in the input switch unit, a failure of the failure detection target switch element is detected based on a voltage across the first power storage element, and the failure detection target switch element outputs the output When included in the switch unit, the failure is based on the voltage across the second storage element. Detecting a failure of the target switching element output, the power transmission insulating circuit according to claim 1. The power transmission insulating circuit further includes:
A third voltage detector for detecting an input voltage that is a voltage between the first end of the first switch element and the first end of the second switch element;
The said control part detects the failure of the said 1st switch element and the said 2nd switch element based on the difference of the both-ends voltage of the said 1st electrical storage element, and the said input voltage. Insulation circuit for power transmission.   The control unit sets an initial value of a difference between the input voltage and a voltage between both ends of the first power storage element or a voltage between the both terminals in a state where at least one of the first switch element and the second switch element is turned off. And the difference between the initial value and the input voltage newly detected in a state in which at least one of the first switch element and the second switch element is turned off and the voltage across the first power storage element And detecting a failure of the first switch element and the second switch element based on a comparison result. The controller detects a failure of the third switch element and the fourth switch element based on a difference between a voltage across the first power storage element and a voltage across the second power storage element;
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 the switch elements and output switches in the input switch unit A second period for turning off the switch elements in the input section, a third period for turning off the switch elements in the input switch section and turning on the switch elements in the output switch section, 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 detects a failure of the third switch element and the fourth switch element in the second period, and detects the failure of the first switch element and the second switch element in the fourth period. The insulation circuit for electric power transmission of Claim 3 which detects a failure. The power transmission isolation circuit has a normal operation mode and a failure detection mode,
In the normal operation mode, 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 the respective units in the input switch unit. A second period in which the switch elements are turned off and the switch elements in the output switch section are turned on in turn,
The control unit executes the first period and the second period in the failure detection mode, and sets the first period and the second period longer than the normal operation mode, The insulation circuit for electric power transmission of any one of Claim 1 to 4.   The control unit outputs a control signal to the first switch element to the fourth switch element, respectively, while insulating between itself and the first switch element to the fourth switch element. The insulating circuit for power transmission according to any one of claims 1 to 6, wherein switching of the first switch element to the fourth switch element is controlled.   The control unit includes a plurality of photocouplers provided corresponding to each of the first switch element to the fourth switch element, and sends the control signal to the first switch element via the corresponding photocoupler. The insulating circuit for power transmission according to claim 7, wherein the circuit is output to each of the switch element and the fourth switch element. 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 is capable of detecting a failure of the first switch element to the fourth switch element at a predetermined timing, and at a timing based on a command from the outside of the power transmission insulating circuit. The insulation circuit for power transmission according to any one of claims 1 to 8, wherein a failure of the first switch element to the fourth switch element can be detected. The power transmission insulating circuit further includes:
The electric power according to any one of claims 1 to 9, further comprising a third power storage element connected between a first end of the first switch element and a first end of the second switch element. Transmission insulation circuit. 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 first power storage element having a first end and a second end;
A second power storage element having a first end and a second end;
A first switch element connected between the rectifying unit and a first end of the first power storage element, and a second switch element connected between the rectifying unit and a second end of the first power storage element. An input switch unit for supplying the first power storage device with the power rectified by the rectification unit,
A third switch element connected between a first end of the first power storage element and a first end of the second power storage element, and a second end of the first power storage element and the second power storage An output switch unit including a fourth switch element connected between the second end of the element and supplying power stored in the first power storage element to the second power storage element;
A first voltage detector for detecting a voltage across the first power storage element;
A second voltage detector for detecting a voltage across the second power storage element;
Based on the voltage across the first power storage element detected by the first voltage detector and the voltage across the second power storage element detected by the second voltage detector, the first voltage detector And a control unit for detecting a failure of the switch element or the fourth switch element.

Images