JP2012157211A - 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 improving the reliability of a circuit by detecting a fault of a switch element by a simple configuration 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; an output switch part 22 including switch elements Z3 and Z4; a temperature detection part 15 for detecting the temperatures of at least two of the switch element Z1 to the switch element Z4; and a control part 14 for comparing the temperatures of the respective switch elements detected by the temperature detection part 15 and detecting a fault of the switch element in the input switch part 21 or the output switch part 22 on the basis of a comparison result.

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 simple configuration in a circuit that transmits power while insulating the input side and the output side. Thus, 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 the first switch element to the fourth switch element. A temperature detection unit for detecting at least any two of the temperatures, and the temperature of each of the switch elements detected by the temperature detection unit, and the input switch unit or the output switch unit based on the comparison result And a controller for detecting a failure of the switch element.

  With such a configuration, failure detection of the power transmission insulating circuit can be realized at low cost with a simple configuration and processing. In addition, short circuit failure of each switch element is detected, error output and system shutdown are performed at the time of failure, and a short circuit between the input side and output side of the insulation circuit for power transmission by taking necessary measures. It is possible to prevent problems caused by Thereby, the reliability of the whole system can be improved. 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 simple configuration.

  Preferably, the control unit calculates a difference between the detected temperatures of the switch elements, and when the calculated difference is equal to or greater than a first threshold, the input switch unit or the output switch unit It is determined that the switch element has failed.

  As described above, the configuration using the threshold value of the temperature difference makes it possible to determine the failure of each switch element with a simple process.

  More preferably, the control unit determines that the temperature of the switch element is in an abnormally rising state when the temperature of the switch element detected by the temperature detection unit is equal to or higher than a second threshold, and the control And when the calculated difference is substantially zero and the temperature of each switch element is lower than a third threshold value lower than the second threshold value, the first switch element to the fourth switch It is determined that the switch element has failed.

  With such a configuration, even if it is difficult to determine a failure with a temperature difference because all of the first switch element to the fourth switch element are short-circuited, the failure of the first switch element to the fourth switch element is detected. Therefore, the reliability of the circuit can be further improved.

  Preferably, the temperature detection unit detects a temperature of the first switch element to the fourth switch element, and the control unit detects the first switch element to the first switch element detected by the temperature detection unit. The temperature of the four switch elements is compared, and a failure of the switch element in the input switch section or the output switch section is detected based on the comparison result.

  As described above, by detecting all the temperatures of the first switch element to the fourth switch, it is possible to more reliably detect a failure of each switch element in the power transmission insulating circuit.

  Preferably, the input switch unit further includes a first diode and a second diode connected in series to the first switch element and the second switch element, respectively, and the output switch unit further includes: A third diode and a fourth diode connected in series to the third switch element and the fourth switch element, respectively, and the temperature detection unit further includes the first diode to the fourth diode. At least any two of the temperatures are detected, and the control unit further compares the temperatures of the diodes detected by the temperature detection unit, and the input switch unit or the output switch unit based on the comparison result The failure of the diode in is detected.

  As described above, in addition to the switch element, the circuit that transmits power while insulating the input side and the output side by detecting the temperature of the diode and detecting the failure can prevent the switch element and the diode from failing with a simple configuration. By detecting, the reliability of the circuit can be further improved.

  More preferably, the first threshold value can be changed.

  With such a configuration, the threshold value can be set flexibly in accordance with the usage environment of the power transmission insulating circuit, so that the failure of each switch element can be reliably detected regardless of the usage environment.

  More preferably, the first end and the second end of the second power storage element are connected to a load, and the first threshold value is large when the output current from the power transmission insulating circuit to the load is large. When the output current from the power transmission insulating circuit to the load is small, the value is set small.

  With such a configuration, a threshold value can be appropriately set according to the type of load to be supplied with power, and a failure of each switch element can be reliably detected.

  Preferably, the first switch element to the fourth switch element have a PN junction.

  Since a switch element such as an IGBT having a PN junction has a significantly reduced ON voltage at the time of a short-circuit failure compared to a normal state, the configuration using such a switch element facilitates the setting of the first threshold value. Failure determination can be performed more accurately.

  Preferably, the control unit controls on / off of the first switch element to the fourth switch element, the control unit turns on each of the switch elements in the input switch unit, and outputs the output A first period in which the switch elements in the switch unit are turned off; a second period in which the switch elements in the input switch unit and the switch elements in the output switch unit are turned off; A third period in which each switch element is turned off and each switch element in the output switch section is turned on, and each switch element in the input switch section and each switch element in the output switch section is turned off. Are repeated in this order.

  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.

  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; The temperature detection unit for detecting the temperature of at least any two of the one switch element to the fourth switch element is compared with the temperature of each of the switch elements detected by the temperature detection unit, and the comparison result is obtained. And a control unit for detecting a failure of the switch element in the input switch unit or the output switch unit.

  With such a configuration, failure detection of the power transmission insulating circuit can be realized at low cost with a simple configuration and processing. In addition, short circuit failure of each switch element is detected, error output and system shutdown are performed at the time of failure, and a short circuit between the input side and output side of the insulation circuit for power transmission by taking necessary measures. It is possible to prevent problems caused by Thereby, the reliability of the whole system can be improved. 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 simple configuration.

  According to the present invention, in a circuit that transmits power while insulating the input side and the output side, it is possible to improve the reliability of the circuit by detecting a failure of the switch element with a simple configuration.

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 static characteristic of the switch element in the insulation circuit for electric power transmission which concerns on the 1st Embodiment of this invention. It is a figure which shows the generation | occurrence | production loss of the switch element 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 power converter device 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.

[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 C0 to C2, an input switch unit 21, an output switch unit 22, a control unit 14, a temperature detection unit 15, and temperature detection elements K1 to K4. The input switch unit 21 includes switch elements Z1 and Z2 and diodes D1 and D2. The output switch unit 22 includes switch elements Z3 and Z4 and diodes D3 and D4.

  In the power transmission insulating circuit 101, the switch elements Z1 to Z4 are, for example, N-channel IGBTs (Insulated Gate Bipolar Transistors). The switch elements Z1 to Z4 may be other types of transistors such as a MOS (Metal Oxide Semiconductor) FET (Field Effect Transistor).

  Here, the first end and the second end of the switch element Z1 correspond to the collector and the emitter of the switch element Z1, respectively, and the first end and the second end of the switch element Z2 correspond to the emitter and the collector of the switch element Z2, respectively. The first end and the second end of the switch element Z3 correspond to the collector and emitter of the switch element Z3, respectively, and the first end and the second end of the switch element Z4 correspond to the emitter and collector of the switch element Z4, respectively.

  The diodes D <b> 1 to D <b> 4 are provided to prevent a backflow of current in the power transmission insulating circuit 101.

  Switch element Z1 has a first end electrically connected to first end T11 of capacitor C0 via diode D1, and a second end electrically connected to first end T13 of capacitor C1. Switch element Z2 has a first end electrically connected to second end T12 of capacitor C0 via diode D2, and a second end electrically connected to second end T14 of capacitor C1. Switch element Z3 has a first end electrically connected to first end T13 of capacitor C1 through diode D3, and a second end electrically connected to first end T15 of capacitor C2. Switch element Z4 has a first end electrically connected to second end T14 of capacitor C1 through diode D4, and a second end electrically connected to second end T16 of capacitor C2.

  The diode D1 is connected between the first end T11 of the capacitor C0 and the first end of the switch element Z1. The diode D2 is connected between the second end T12 of the capacitor C0 and the first end of the switch element Z2. The diode D3 is connected between the first end T13 of the capacitor C1 and the first end of the switch element Z3. The diode D4 is connected between the second end T14 of the capacitor C1 and the first end of the switch element Z4.

  More specifically, the diode D1 has an anode electrically connected to the first terminal T11 of the capacitor C0 and a cathode electrically connected to the collector of the switch element Z1. Diode D2 has an anode electrically connected to the emitter of switching element Z2 and a cathode electrically connected to second end T12 of capacitor C0. The diode D3 has an anode electrically connected to the first terminal T13 of the capacitor C1 and a cathode electrically connected to the collector of the switch element Z3. The diode D4 has an anode electrically connected to the emitter of the switching element Z4 and a cathode electrically connected to the second terminal T14 of the capacitor C1.

  Switch element Z1 has a collector electrically connected to the cathode of diode D1, an emitter electrically connected to first terminal T13 of capacitor C1, and a gate for receiving gate control signal G1 from control unit 14. Have. Switch element Z2 has a collector electrically connected to second end T14 of capacitor C1, an emitter electrically connected to the anode of diode D2, and a gate for receiving gate control signal G2 from control unit 14. Have. Switch element Z3 has a collector electrically connected to the cathode of diode D3, an emitter electrically connected to first terminal T15 of capacitor C2, and a gate for receiving gate control signal G3 from control unit 14. Have. Switch element Z4 has a collector electrically connected to second end T16 of capacitor C2, an emitter electrically connected to the anode of diode D4, and a gate for receiving gate control signal G4 from control unit 14. Have.

  The first end T15 of the capacitor C2 and the plus side terminal of the load 302 are connected, and the second end T16 of the capacitor C2 and the minus side terminal of the load 302 are connected.

  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 capacitor C 0 stores the power rectified by the rectifying unit 51. The input switch unit 21 supplies the power received at the first end of the switch element Z1 and the first end 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. 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.

  The temperature detection elements K1 to K4 are, for example, a thermistor, a thermocouple, or a diode. The temperature detection elements K1 to K4 are provided in the vicinity of the switch elements Z1 to Z4 or in contact with the switch elements Z1 to Z4, respectively, and output a voltage or current indicating the temperature of the switch elements Z1 to Z4 to the temperature detection unit 15.

  The temperature detection unit 15 detects the temperature of each of the temperature detection elements K1 to K4 based on the voltage or current received from the temperature detection elements K1 to K4, and outputs a signal indicating the detection result to the control unit 14.

  Based on the signal received from temperature detection unit 15, control unit 14 determines failure of switch elements Z <b> 1 to Z <b> 4.

[Operation]
Next, the operation when the power transmission insulating circuit according to the first embodiment of the present invention performs power transmission 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.

  Then, the control unit 14 repeats the period T1, the period T2, the period T3, and the period T4 in this order, so that the input side and the output side of the power transmission insulating circuit 101 are insulated and cooperated with the rectifying unit 51. The AC power from the AC power supply 301 is converted into DC power and supplied to the load 302.

  Next, the operation when the insulation circuit for power transmission according to the first embodiment of the present invention performs failure determination of the switch element will be described with reference to the drawings.

  FIG. 3 is a diagram showing the static characteristics of the switch element in the power transmission insulating circuit according to the first embodiment of the present invention. FIG. 3 shows the measured static characteristics, that is, current-voltage characteristics of a normal product and a short-circuit faulty product when the gate-emitter voltage is 15 V for a switching element that is an IGBT having a withstand voltage of 1200 V and a maximum collector current of 60 A (amperes). Results are shown. In the graph of FIG. 3, the horizontal axis represents the collector-emitter voltage VCE in the switch element, and the vertical axis represents the collector current IC in the switch element.

  Referring to FIG. 3, it can be seen that the collector-emitter voltage VCE for the same collector current IC is significantly smaller in the short-circuit failure product than in the normal product.

  Therefore, when the power transmission insulating circuit 101 including the short-circuit failure product is operated as it is, the generation loss of the short-circuit failure product and the generation loss of the normal product are different.

  FIG. 4 is a diagram showing a generated loss of the switch element in the power transmission insulating circuit according to the first embodiment of the present invention. FIG. 4 is a diagram comparing the loss generated in a normal IGBT product and the loss generated in a short-circuit failure product.

  Specifically, FIG. 4 shows that when the output power of the power transmission insulating circuit 101 is 3 kW and the DC level of the output voltage is 300 V, one of the four IGBTs in the power transmission insulating circuit 101 is The theoretically calculated values of the loss of normal products and the loss of short-circuit products when a short-circuit failure occurs are shown. This theoretical calculation value was calculated using the static characteristics shown in FIG.

  From the theoretical calculation results shown in FIG. 4, the loss of the short circuit failure product is predicted to be about 1/5 of the normal product. That is, a difference occurs between the temperature rise of the short-circuit faulty product and the temperature rise of the normal product. For example, it is possible to calculate the difference between the temperature rise of the short-circuit faulty product and the temperature rise of the normal product using the relationship of 2.9 ° C./W.

  On the other hand, when all of the switch elements Z1 to Z4 are operating normally, the temperature rise of the switch elements Z1 to Z4 is substantially uniform.

  Therefore, in the power transmission insulating circuit 101, the temperature detection elements K1 to K4 are attached to the switch elements Z1 to Z4 in a contact or non-contact state, respectively, or formed on a semiconductor chip.

  And when the temperature of switch element Z1-Z4 is notified to the control part 14 via the temperature detection part 15, and the temperature difference between switch elements Z1-Z4 becomes large, at least of switch element Z1-Z4 It is determined that any one switch element has a short circuit failure.

  That is, the temperature detection unit 15 detects the temperature of the switch element Z1 to the switch element Z4. The control unit 14 compares the temperatures of the switch elements Z1 to Z4 detected by the temperature detection unit 15, and detects a failure of the switch element in the input switch unit 21 or the output switch unit 22 based on the comparison result.

  Specifically, the control unit 14 calculates a difference between the detected temperatures of the switch elements Z1 to Z4, and when the calculated difference is equal to or greater than the threshold value DTh1, the switch in the input switch unit 21 or the output switch unit 22 It is determined that the element has failed.

  Control unit 14 may further perform an operation of detecting a failure of each switch element based on the temperature of each of switch elements Z1 to Z4.

  That is, when the temperature of the switch element detected by the temperature detector 15 is equal to or higher than the threshold value ATh1, the control unit 14 determines that the temperature of the switch element is in an abnormally rising state. Here, the threshold value ATh1 is a threshold value for detecting an abnormal temperature rise performed by an IPM (Intelligent Power Module) or the like in order to prevent thermal destruction of the device, for example.

  When the difference between the detected temperatures of the switch elements Z1 to Z4 is substantially zero and the temperature of the switch elements Z1 to Z4 is lower than the threshold value ATh2 lower than the threshold value ATh1, the control unit 14 switches the switch element Z1. It is determined that Z4 has failed.

  The threshold value DTh1 may be changeable. As an example of a method for setting the threshold value DTh1, it is conceivable to set the threshold value DTh1 according to the current flowing through the circuit. That is, it is desirable that the temperature difference threshold value DTh1 for determining a failure is variable according to the output current of the power transmission insulating circuit 101, for example.

  More specifically, the threshold value DTh1 is set large when the output current from the power transmission insulating circuit 101 to the load 302 is large, and is small when the output current from the power transmission insulating circuit 101 to the load 302 is small. Is set.

  Specifically, when the output power of the power transmission insulating circuit 101 is 3 kW, it is assumed that the temperature rise difference between the normal switch element and the short-circuit switch element is 40 ° C. In this case, the threshold value DTh1 may be set to 20 ° C.

  Further, when the output power of the power transmission insulating circuit 101 is 500 W, it is assumed that the temperature rise difference between the normal switch element and the short-circuit switch element is 4 ° C. In this case, the threshold value DTh1 may be set to 2 ° C to 3 ° C.

  By the way, in the insulation circuit for power supply devices described in Patent Document 1, when a switch element in each switch circuit fails and is short-circuited, insulation between the input side and the output side may not be ensured. The same applies to the power transmission insulating circuit 101.

  That is, in the power transmission insulating circuit 101 which is a transformer-less insulating circuit, the insulation between the input and the output is ensured by the withstand voltage of the switch elements such as IGBTs and MOSFETs. For this reason, in order to improve the reliability of the system using the insulating circuit 101 for power transmission, it becomes a subject to implement | achieve the detection function of the short circuit fault of a switch element cheaply. Note that in the case of a switch element open failure, power cannot be passed between the input and output of the power transmission insulating circuit 101, so there is less possibility of occurrence of a failure compared to a short-circuit failure, and the detection is easy. is there.

  As a failure detection method for a short-circuit failure of each switch element, for example, a method of monitoring the output voltage from the power transmission insulating circuit 101 to the load 302 is conceivable. However, in the power transmission insulating circuit 101, even if one switch element is short-circuited, the level of the output voltage does not substantially change. Therefore, it is difficult to reliably detect a short-circuit fault of the switch element by such a method. is there.

  Although a method for monitoring the voltage in the power transmission insulating circuit 101 is also conceivable, a separate voltage detector is required, and a process for determining whether the internal voltage is normal or abnormal is necessary. Becomes complicated.

  On the other hand, in the power transmission insulating circuit according to the first embodiment of the present invention, the temperature detection unit 15 detects the temperatures of the switch elements Z1 to Z4. And the control part 14 compares the temperature of each switch element detected by the temperature detection part 15, and detects the failure of the switch element in the input switch part 21 or the output switch part 22 based on a comparison result.

  That is, paying attention to the difference in static characteristics between the normal switch element and the short-circuit faulty switch element, it takes advantage of the fact that the temperature rise during operation differs between the normal product and the short-circuit faulty product. Perform detection.

  Moreover, the temperature detection element for detecting the temperature of each switch element is usually provided for protection of these switch elements in many cases. In the power transmission insulating circuit 101, the temperature difference between the switch elements Z1 to Z4 is calculated by using a protective temperature detection element without separately providing a voltage detection unit or the like, and failure detection is performed.

  With such a configuration, failure detection of the power transmission insulating circuit 101 can be realized at low cost with a simple configuration and processing.

  In addition, when a short circuit failure of each switch element is detected, an error output is performed and the system is stopped at the time of the failure, and a user or the like takes necessary measures so that the input side and the output side of the power transmission insulating circuit 101 are connected. It is possible to prevent a malfunction due to a short circuit. Thereby, the reliability of the whole system can be improved.

  Therefore, in the power transmission insulating circuit according to the first embodiment of the present invention, in the circuit that transmits power while insulating the input side and the output side, by detecting a failure of the switch element with a simple configuration, The reliability of the circuit can be improved.

  Further, in the power transmission insulating circuit according to the first embodiment of the present invention, the control unit 14 calculates a difference between the detected temperatures of the respective switch elements, and the calculated difference is equal to or greater than the threshold value DTh1. Determines that the switch element in the input switch unit 21 or the output switch unit 22 has failed.

  As described above, the configuration using the temperature difference threshold value DTh1 makes it possible to determine the failure of each switch element with a simple process.

  In the power transmission insulating circuit according to the first embodiment of the present invention, when the temperature of the switch element detected by the temperature detection unit 15 is equal to or higher than the threshold value ATh1, the control unit 14 It is determined that the temperature is abnormally rising. When the difference between the detected temperatures of the switch elements is substantially zero and the temperature of each switch element is lower than the threshold value ATh2 lower than the threshold value ATh1, the control unit 14 fails in the switch elements Z1 to Z4. It is determined that

  With such a configuration, since all of the switch elements Z1 to Z4 are short-circuited, it is possible to detect a failure of the switch elements Z1 to Z4 even when it is difficult to determine a failure with a temperature difference, thereby further improving circuit reliability. Can be made.

  Further, in the power transmission insulating circuit according to the first embodiment of the present invention, the threshold value DTh can be changed.

  With such a configuration, the threshold value DTh1 can be set flexibly in accordance with the use environment of the power transmission insulating circuit 101. Therefore, the failure of each switch element can be reliably detected regardless of the use environment. .

  Further, in the power transmission insulating circuit according to the first embodiment of the present invention, the threshold value DTh is set large when the output current from the power transmission insulating circuit 101 to the load 302 is large, and the power transmission insulating circuit When the output current from the circuit 101 to the load 302 is small, it is set small.

  With such a configuration, the threshold value DTh1 can be appropriately set according to the type of load to be supplied with power, and a failure of each switch element can be reliably detected.

  In the power transmission insulating circuit according to the first embodiment of the present invention, the switch elements Z1 to Z4 have PN junctions.

  Since a switch element such as an IGBT having a PN junction has a significantly lower ON voltage at the time of a short-circuit failure than that at a normal time, the configuration using such a switch element facilitates the setting of the threshold value DTh1 and determines the failure. Can be performed more accurately.

  In the power transmission insulating circuit according to the first embodiment of the present invention, the control unit 14 turns on each switch element in the input switch unit 21 and turns off each switch element in the output switch unit 22. T1, a period T2 in which each switch element in the input switch section 21 and each switch element in the output switch section 22 are turned off, each switch element in the input switch section 21 is turned off, and each switch element in the output switch section 22 is turned on Period T3 during which the switching elements in the input switch section 21 and the switching elements in the output switch section 22 are turned off are repeated in this order.

  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.

  Although the power transmission insulating circuit according to the first embodiment of the present invention is configured to detect the temperatures of the switch elements Z1 to Z4, the present invention is not limited to this, and the switch elements Z1 to Z4 are not limited thereto. If it is the structure which detects the temperature of at least any two of these, it is possible to achieve the object of the present invention to improve the reliability of the circuit by detecting the failure of the switch element with a simple structure It is.

  On the other hand, with the configuration that detects all the temperatures of the switch elements Z1 to Z4, it is possible to more reliably detect the failure of each switch element in the power transmission insulating circuit 101.

  Further, the power transmission insulating circuit 101 may be configured not to include 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, when the rectifying unit 51 is provided with a capacitor for storing the rectified power, a configuration in which the capacitor C0 is not provided in the power transmission insulating circuit 101 is possible.

  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.

  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 a temperature detection target is added 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. 5 is a diagram showing a configuration of a power conversion device according to the second embodiment of the present invention.

  Referring to FIG. 5, power conversion device 202 includes a power transmission insulating circuit 102 and a rectifying unit 51. Compared with the power transmission insulating circuit 101, the power transmission insulating circuit 102 further includes temperature detection elements K5 to K8.

  Similarly to the power transmission insulating circuit 101, the input switch unit 21 includes a diode D1 and a diode D2 connected in series to the switch element Z1 and the switch element Z2, respectively.

  The output switch unit 22 includes a diode D3 and a diode D4 connected in series to the switch element Z3 and the switch element Z4, respectively, similarly to the power transmission insulating circuit 101.

  The temperature detection elements K5 to K8 are, for example, a thermistor, a thermocouple, or a diode. The temperature detection elements K5 to K8 are provided in the vicinity of the diodes D1 to D4 or in contact with the diodes D1 to D4, respectively, and output a voltage or current indicating the temperature of the diodes D1 to D4 to the temperature detection unit 15.

  The temperature detection unit 15 detects the temperatures of the diodes D1 to D4 based on the voltage or current received from the temperature detection elements K5 to K8, and outputs a signal indicating the detection result to the control unit 14.

  Based on the signal received from temperature detection unit 15, control unit 14 determines failure of diodes D <b> 1 to D <b> 4.

  In the power transmission insulating circuit 102, the temperature detection elements K5 to K8 are attached to the diodes D1 to D4 in a contact or non-contact state, respectively, or formed on a semiconductor chip.

  Then, the temperature of the diodes D1 to D4 is notified to the control unit 14 via the temperature detection unit 15, and when the temperature difference between the diodes D1 to D4 becomes large, at least one of the diodes D1 to D4. Judge that two diodes have a short-circuit fault.

  That is, the control unit 14 compares the temperature of each diode detected by the temperature detection unit 15 and detects a failure of the diode in the input switch unit 21 or the output switch unit 22 based on the comparison result.

  Specifically, the control unit 14 calculates the difference between the detected temperatures of the diodes D1 to D4, and when the calculated difference is equal to or greater than the threshold value DTh2, the diode in the input switch unit 21 or the output switch unit 22 Is determined to have failed.

  As described above, in the power transmission insulating circuit according to the second embodiment of the present invention, the temperature detection and failure detection of the reverse blocking diodes D1 to D4 are performed in addition to the switching elements Z1 to Z4. With such a configuration, in a circuit that transmits power while insulating the input side and the output side, the reliability of the circuit can be further improved by detecting a failure of the switch element and the diode with a simple configuration. .

  Although the power transmission insulating circuit according to the second embodiment of the present invention is configured to detect the temperatures of the diodes D1 to D4, the invention is not limited to this, and the diodes D1 to D4 are not limited thereto. Any configuration that detects at least any two of the temperatures may be used.

  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 15 Temperature detection part 21 Input switch part 22 Output switch part 101,102 Insulation circuit for electric power transmission 51 Rectification part 201,202 Power converter 301 AC power supply 302 Load C0-C2 Capacitor K1- K8 Temperature detection element Z1, Z2, Z3, Z4 Switch element

Claims (10)

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 temperature detector for detecting the temperature of at least any two of the first switch element to the fourth switch element;
A control unit for comparing the temperatures of the switch elements detected by the temperature detection unit and detecting a failure of the switch element in the input switch unit or the output switch unit based on a comparison result. Transmission insulation circuit.   The control unit calculates a difference between the detected temperatures of the switch elements, and when the calculated difference is equal to or greater than a first threshold, the switch element in the input switch unit or the output switch unit is The insulation circuit for power transmission according to claim 1, wherein it is determined that a failure has occurred. The controller determines that the temperature of the switch element is abnormally increased when the temperature of the switch element detected by the temperature detector is equal to or higher than a second threshold value,
When the calculated difference is substantially zero and the temperature of each switch element is lower than a third threshold value that is lower than the second threshold value, the controller switches the first switch element to the first switch element. The insulating circuit for power transmission according to claim 2, wherein the switch element of 4 is determined to have failed. The temperature detection unit detects a temperature of the first switch element to the fourth switch element,
The control unit compares temperatures of the first switch element to the fourth switch element detected by the temperature detection unit, and the switch element in the input switch unit or the output switch unit based on a comparison result The insulation circuit for power transmission according to any one of claims 1 to 3, wherein a failure of the power is detected. The input switch unit further includes a first diode and a second diode connected in series to the first switch element and the second switch element, respectively.
The output switch unit further includes a third diode and a fourth diode connected in series to the third switch element and the fourth switch element,
The temperature detector further detects the temperature of at least any two of the first diode to the fourth diode,
The control unit further compares the temperature of each of the diodes detected by the temperature detection unit, and detects a failure of the diode in the input switch unit or the output switch unit based on a comparison result. The insulating circuit for power transmission according to any one of claims 1 to 4.   The insulation circuit for power transmission according to claim 2, wherein the first threshold value can be changed. The first end and the second end of the second power storage element are connected to a load,
The first threshold value is set large when the output current from the power transmission insulating circuit to the load is large, and is set small when the output current from the power transmission insulating circuit to the load is small. The insulation circuit for power transmission according to claim 6.   8. The power transmission insulating circuit according to claim 1, wherein each of the first switch element to the fourth switch element has a PN junction. 9. The control unit controls on / off of the first switch element to 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 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 The insulating circuit for power transmission according to any one of claims 1 to 8, wherein the switch elements in the unit and the fourth period in which the switch elements in the output switch unit are turned off are repeated in this order. . 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 temperature detector for detecting the temperature of at least any two of the first switch element to the fourth switch element;
A control unit for comparing the temperatures of the switch elements detected by the temperature detection unit and detecting a failure of the switch element in the input switch unit or the output switch unit based on a comparison result. Conversion device.

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