WO2015053106A1 - Overheating protector - Google Patents

Overheating protector Download PDF

Info

Publication number
WO2015053106A1
WO2015053106A1 PCT/JP2014/075782 JP2014075782W WO2015053106A1 WO 2015053106 A1 WO2015053106 A1 WO 2015053106A1 JP 2014075782 W JP2014075782 W JP 2014075782W WO 2015053106 A1 WO2015053106 A1 WO 2015053106A1
Authority
WO
WIPO (PCT)
Prior art keywords
switch
thermal resistor
load
overheat protection
power supply
Prior art date
Application number
PCT/JP2014/075782
Other languages
French (fr)
Japanese (ja)
Inventor
佑典 矢野
克馬 塚本
Original Assignee
株式会社オートネットワーク技術研究所
住友電装株式会社
住友電気工業株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 株式会社オートネットワーク技術研究所, 住友電装株式会社, 住友電気工業株式会社 filed Critical 株式会社オートネットワーク技術研究所
Publication of WO2015053106A1 publication Critical patent/WO2015053106A1/en

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
    • H02H5/04—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature
    • H02H5/042—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature using temperature dependent resistors
    • H02H5/043—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature using temperature dependent resistors the temperature dependent resistor being disposed parallel to a heating wire, e.g. in a heating blanket

Definitions

  • the present invention comprises a switch for turning on and off the power supply to the load, a heat generating part that generates heat by the power supply to the load or a thermal resistor thermally coupled to the switch, and according to the potential difference between both ends of the thermal resistor,
  • the present invention relates to an overheat protection device that turns off the switch.
  • an overheat protection circuit that includes a positive temperature coefficient thermistor for detecting overheating of a load and a switching transistor that cuts off power supply to the load, and that shuts off current to the load when the overheating of the load is detected.
  • a positive temperature coefficient thermistor for detecting overheating of a load and a switching transistor that cuts off power supply to the load, and that shuts off current to the load when the overheating of the load is detected.
  • One end of the positive temperature coefficient thermistor is connected to the power supply potential.
  • the overheat protection circuit is configured such that the switching transistor is turned on and off according to the voltage on the other end side of the positive temperature coefficient thermistor.
  • the other end of the positive temperature coefficient thermistor is grounded via a voltage dividing resistor.
  • the collector of the control transistor is connected to the gate of the switching transistor via a resistor, and the emitter of the control transistor is grounded via a reversely connected Zener diode. Further, the voltage divided by the voltage dividing resistor is applied to the base of the control transistor.
  • the overheat protection circuit configured in this way, when the temperature of the positive temperature coefficient thermistor rises, the voltage drop due to the positive temperature coefficient thermistor increases and the switching transistor is turned off. When the switching transistor is turned off, the power supply to the load is cut off. On the contrary, when the temperature of the positive temperature coefficient thermistor decreases, the switching transistor is turned on, and the power supply to the load is resumed.
  • the conventional overheat protection circuit when the power supply potential fluctuates, the voltage on the other end side of the positive temperature coefficient thermistor also varies, and the temperature threshold value of the positive temperature coefficient thermistor that turns off the switching transistor changes. there were.
  • the power supply potential may fluctuate during operation of the in-vehicle device, such as during power generation by an alternator or when starting an engine. If the temperature threshold value changes, the control transistor malfunctions and appropriate overheat protection cannot be performed.
  • the present invention has been made in view of such circumstances, and appropriately protects a switch for turning on and off the power supply to the load or a heat generating portion that generates heat by the power supply to the load without being affected by fluctuations in the power supply potential.
  • An object of the present invention is to provide an overheat protection device that can be used.
  • An overheat protection device includes a switch for turning on and off power supply to a load, a heat generating part that generates heat by power supply to the load, or a thermal resistor thermally coupled to the switch, and supplies a constant current to the thermal resistor. And a control circuit for turning off the switch in accordance with a potential difference between both ends of the thermal resistor.
  • the temperature of the thermal resistor also changes in response to the temperature of the heat generating part or the switch. Since a constant current is supplied to the thermal resistor, the relationship between the temperature of the thermal resistor and the potential difference between both ends of the thermal resistor does not vary depending on the power supply potential.
  • the control circuit turns off the switch according to the potential difference between both ends of the thermal resistor. Therefore, the switch is turned off according to the temperature of the heat generating part and the switch without being affected by the voltage fluctuation of the power supply potential, and the power supply to the load is cut off.
  • the overheat protection device is characterized in that the control circuit includes an FET having a source connected to a high potential side of the thermal resistor and a gate connected to a low potential side of the thermal resistor. .
  • the threshold voltage at which FET (Field Effect Transistor) is turned on / off increases when the source potential increases and decreases when the source potential decreases. Since the source of the FET is connected to the high potential side of the thermal resistor, when the voltage on the high potential side of the thermal resistor fluctuates, the threshold voltage at which the FET turns on and off also follows the fluctuation of the voltage. fluctuate. Therefore, the FET is turned on / off according to the voltage drop of the thermal resistor regardless of the voltage fluctuation on the high potential side of the thermal resistor.
  • the overheat protection device is characterized in that the FET is a P-channel MOSFET or an N-channel junction FET.
  • a P-channel type MOSFET Metal Oxide Semiconductor Field Effect Transistor
  • MOSFET Metal Oxide Semiconductor Field Effect Transistor
  • the N-channel junction FET is turned on / off according to the voltage drop of the thermal resistor regardless of the voltage fluctuation on the high potential side of the thermal resistor.
  • the thermal resistor is a positive temperature coefficient thermistor
  • the control circuit has one terminal connected to the gate of the switch and an on / off terminal connected to the P-channel MOSFET or N-channel junction type.
  • a transistor is connected to the drain of the FET and the other terminal is grounded.
  • the P-channel MOSFET and the transistor are turned on and the switch is turned off when the temperature of the thermal resistor exceeds a predetermined temperature. That is, the power supply to the load is interrupted.
  • the N-channel junction FET is turned on and the switch is turned off when the temperature of the thermal resistor exceeds a predetermined temperature. That is, the power supply to the load is interrupted.
  • the overheat protection device is characterized in that the thermal resistor is electrically connected to the switch.
  • the thermal resistor is electrically connected to the switch and thermally coupled. Thus, the heat of the switch is immediately transferred to the thermal resistor.
  • the switch for turning on / off the power supply to the load or the heat generating part that generates heat by the power supply to the load can be appropriately protected without being affected by the fluctuation of the power supply potential.
  • FIG. 1 is a circuit block diagram conceptually showing the configuration of the overheat protection device
  • FIG. 2 is a circuit diagram showing a configuration example of the overheat protection device.
  • the overheat protection device includes a power source 1, a switch 2, a load 3, a thermal resistor 4, a constant current circuit 5 and a control circuit 6.
  • the overheat protection device is mounted on a vehicle, for example.
  • the power source 1 is, for example, a vehicle battery such as a lead storage battery or a lithium ion battery.
  • the lead acid battery includes a positive electrode plate, a negative electrode plate, and an electrolytic solution.
  • the positive electrode of the power source 1 is connected to the load 3 via the switch 2, and the power source 1 supplies power to the load 3 by a chemical reaction.
  • the lead storage battery and the lithium ion battery are examples of the power source 1 and are not particularly limited as long as they can supply necessary power to the load 3.
  • the switch 2 is an element that turns on and off the power supply to the load 3.
  • the switch 2 is an element that generates heat when power is supplied to the load 3.
  • the switch 2 is a protection target of the overheat protection device in the present embodiment.
  • the switch 2 is, for example, an N channel type MOSFET.
  • the drain of the switch 2 is connected to the positive electrode of the power source 1, and the source is connected to one end of the load 3.
  • the gate of the switch 2 is connected to the control circuit 6.
  • the switch 2 is turned on / off in response to a control signal from the control circuit 6. Specifically, when a high level signal is applied from the control circuit 6 to the gate of the switch 2, the switch 2 is turned on, and when a low level signal is applied to the gate of the switch 2, the switch 2 is Turn off.
  • the N-channel MOSFET is an example of the switch 2.
  • the switch 2 may be a semiconductor switch such as a P-channel MOSFET, a junction FET, or a bipolar transistor, or may be
  • the load 3 is a device such as a headlamp, a blower motor, and various drive motors mounted on the vehicle.
  • One end of the load 3 is connected to the source of the switch 2 or one end of the thermal resistor 4, and the other end of the load 3 is grounded. That is, the other end of the load 3 is connected to the metal frame of the vehicle.
  • the thermal resistor 4 is a positive temperature coefficient thermistor.
  • the positive temperature coefficient thermistor is a resistor whose resistance value increases as the temperature rises.
  • One end of the thermal resistor 4 is electrically connected to and thermally coupled to the source of the switch 2. That is, the current from the power source 1 flows to the thermal resistor 4 through the switch 2, and the heat of the switch 2 generated by energization is conducted to the thermal resistor 4. More specifically, one end of the thermal resistor 4 is directly connected to the conductive wire of the circuit board on which the switch 2 is arranged. The other end of the thermal resistor 4 is connected to the constant current circuit 5.
  • the constant current circuit 5 is a circuit that supplies a constant current to the thermal resistor 4 regardless of the voltage applied to the thermal resistor 4 and the constant current circuit 5. The magnitude of the constant current will be described later.
  • the control circuit 6 is a circuit that turns off the switch 2 in accordance with the potential difference between both ends of the thermal resistor 4.
  • the control circuit 6 includes a control unit 61 that controls on / off of the switch 2, and a P-channel MOSFET 62 and a transistor 63 for forcibly controlling the switch 2 when the switch 2 is overheated.
  • the control unit 61 is a microcomputer including, for example, a CPU, a ROM, a RAM, a control signal output unit, a CAN communication interface, an I / O port, and the like.
  • An external electronic control unit (ECU: Electronic Control Unit) (not shown) is connected to the CAN communication interface via the CAN.
  • the control signal output unit is connected to the gate of the switch 2.
  • the control unit 61 receives a power supply command to the load 3 from an external electronic control device (not shown)
  • the control unit 61 outputs a high-level control signal from the control signal output unit.
  • the switch 2 can be turned on and power can be supplied to the load 3.
  • the control unit 61 When receiving a power supply stop command to the load 3 from the electronic control unit, the control unit 61 outputs a low-level control signal from the control signal output unit. By applying a low-level control signal to the gate of the switch 2, the switch 2 can be turned off and the power supply to the load 3 can be stopped.
  • the source of the P-channel type MOSFET 62 is connected to the source of the switch 2 and the one end of the thermal resistor 4. That is, the source of the P-channel MOSFET 62 is connected to the source of the switch 2 and the high potential side of the thermal resistor 4.
  • the gate of the P-channel type MOSFET 62 is connected to the other end of the thermal resistor 4, that is, the end on the low potential side.
  • the drain of the P-channel type MOSFET 62 is connected to the base of the transistor 63.
  • an N channel junction type FET may be used.
  • the transistor 63 is, for example, a bipolar transistor.
  • the collector of the transistor 63 is connected to the gate of the switch 2 and the control signal output unit of the control unit 61.
  • the emitter of the transistor 63 is grounded.
  • the bipolar transistor is an example of the transistor 63, and may be composed of an N-channel MOSFET, a P-channel junction FET, or the like.
  • the operation of the overheat protection device configured as described above will be described.
  • the voltage drop due to the thermal resistor 4 is expressed by the following formula (1).
  • the left side of the above formula (2) indicates the voltage applied to the gate of the P-channel MOSFET 62, and the right side indicates the gate voltage at which the P-channel MOSFET 62 is turned on.
  • the above equation (2) can be transformed into the following equation (3).
  • the gate voltage at which the P-channel MOSFET 62 is turned on does not depend on the power supply potential, but is determined by the threshold voltage between the source and drain of the P-channel MOSFET 62. Therefore, the P-channel type MOSFET 62 does not depend on the power supply potential, and is turned on when the voltage drop across the thermal resistor 4 is greater than the threshold voltage. When the voltage drop across the thermal resistor 4 is less than or equal to the threshold voltage, the P-channel MOSFET 62 is turned off. That is, the P-channel MOSFET 62 is turned on when the temperature of the thermal resistor 4 that is a positive temperature coefficient thermistor is high, and turned off when the temperature of the thermal resistor 4 is low.
  • the transistor 63 When the temperature of the thermal resistor 4 is low and the P-channel MOSFET 62 is off, the transistor 63 is off. When the transistor 63 is in the off state, the switch 2 is turned on and off in accordance with the control signal output from the control unit 61. When the temperature of the thermal resistor 4 is high and the P-channel MOSFET 62 is on, the transistor 63 is on. When the transistor 63 is in the ON state, the gate of the switch 2 is grounded. Therefore, even if a high level control signal is output from the control unit 61, the switch 2 is turned off and the power supply to the load 3 is cut off.
  • the constant current value to be supplied by the constant current circuit 5 is represented by the following formula (5) from the above formula (4). Given in.
  • the overheat protection circuit configured in this way can protect the switch 2 from exceeding the threshold temperature without being affected by fluctuations in the power supply potential.
  • the thermal resistor 4 is electrically connected to the switch 2 and thermally coupled, the thermal responsiveness of the overheat protection circuit can be improved. That is, the temperature of the thermal resistor 4 immediately rises following the rise in the temperature of the switch 2, so that when the switch 2 reaches the threshold voltage, the switch 2 can be quickly turned off and the switch 2 is overheated. Can be effectively protected from.
  • overheat protection control of the switch 2 is realized by the P-channel type MOSFET 62 and the transistor 63 of the control circuit 6. Therefore, the overheat protection device has excellent responsiveness to overheating, and can reduce the processing load on the control unit 61.
  • the switch 2 can be controlled to be turned on / off according to the voltage drop of the thermal resistor 4. If it is, it will not be limited to the structure of this Embodiment in particular.
  • the transistor 63 may be eliminated, and the control unit 61 may be configured to perform on / off control of the switch 2 in accordance with the drain voltage of the P-channel MOSFET 62. More specifically, the drain voltage of the P-channel MOSFET 62 may be divided by a voltage dividing resistor, and the divided voltage may be input to the I / O port of the control unit 61.
  • the control unit 61 performs control to forcibly turn off the switch 2 when higher than a predetermined threshold voltage.
  • the P-channel MOSFET 62 may be composed of an N-channel MOSFET or a P-channel or N-channel junction FET.
  • the control unit 61 acquires the voltage value at one end of the thermal resistor 4 and the voltage value at the other end via the I / O port, and the switch 2 is turned on / off according to the difference between the acquired voltage values. You may comprise so that it may control.
  • the thermal resistor 4 has a positive characteristic with respect to heat
  • the switch 2 may be forcibly turned off when the difference is larger than a threshold value.
  • the switch 2 may be forcibly turned off when the difference is smaller than the threshold value.
  • the positive temperature coefficient thermistor was illustrated as the thermal resistor 4, if it is an element from which resistance value changes with temperature, it is not limited to a positive temperature coefficient thermistor.
  • a silver temperature measuring resistor may be used as the thermal resistor 4.
  • the thermal resistor 4 does not have to have a positive characteristic, and may be configured by a negative thermal resistor 4, for example, a negative characteristic thermistor.
  • the negative characteristic thermistor is a resistor whose resistance value decreases as the temperature rises.
  • the collector of the transistor 63 is connected to the gate of the switch 2, the emitter of the transistor 63 is connected to the control signal output unit, and the base is connected to the drain of the P-channel MOSFET 62. Since the thermal resistor 4 has a negative characteristic, when the switch 2 is below the threshold temperature, the P-channel MOSFET 62 is turned on, and the control signal output and the gate of the switch 2 are connected. When the switch 2 is lower than the threshold temperature, the P-channel MOSFET 62 is turned off, the control signal output and the gate of the switch 2 are disconnected, and the power supply to the load 3 is cut off.
  • the switch 2 is protected from overheating.
  • the temperature of an arbitrary overheated portion that is overheated by power supply to the load is detected by the thermal resistor 4 to supply power to the load. You may comprise so that it may interrupt

Abstract

Provided is an overheating protector by which a switch for switching on and off the supply of electricity to a load, or a heat-generating unit for generating heat by the supply of electricity to the load, can be suitably protected irrespective of fluctuations in the power source potential. The overheating protector is provided with: a switch for switching on and off the supply of electricity to a load (3); a heat-sensitive resistor (4) thermally coupled to the switch (2) or the heat-generating unit for generating heat by the supply of electricity to the load (3); a fixed-current circuit (5) for supplying a fixed current to the heat-sensitive resistor (4); and a control circuit (6) for turning off the switch (2) according to the difference in potential between the two terminals of the heat-sensitive resistor (4).

Description

過熱保護装置Overheat protection device
　本発明は、負荷への給電をオンオフするスイッチと、該負荷への給電によって発熱する発熱部又は該スイッチに熱結合した感熱抵抗器とを備え、該感熱抵抗器の両端の電位差に応じて、前記スイッチをオフにする過熱保護装置に関する。 The present invention comprises a switch for turning on and off the power supply to the load, a heat generating part that generates heat by the power supply to the load or a thermal resistor thermally coupled to the switch, and according to the potential difference between both ends of the thermal resistor, The present invention relates to an overheat protection device that turns off the switch.
　負荷の過熱を検知するための正特性サーミスタ及び該負荷への給電を遮断するスイッチングトランジスタを備え、負荷の過熱が検知された場合、該スイッチングトランジスタによって負荷への電流を遮断する過熱保護回路が開示されている（例えば、特許文献１）。正特性サーミスタの一端は電源電位に接続されている。過熱保護回路は、該正特性サーミスタの他端側の電圧に応じて、スイッチングトランジスタがオンオフ動作するように構成されている。
　例えば、正特性サーミスタの他端は分圧抵抗を介して接地されている。スイッチングトランジスタのゲートには、抵抗器を介して制御トランジスタのコレクタが接続され、該制御トランジスタのエミッタは、逆接続されたツェナーダイオードを介して接地されている。また、制御トランジスタのベースには前記分圧抵抗で分圧された電圧が印加されるように構成されている。 Disclosed is an overheat protection circuit that includes a positive temperature coefficient thermistor for detecting overheating of a load and a switching transistor that cuts off power supply to the load, and that shuts off current to the load when the overheating of the load is detected. (For example, Patent Document 1). One end of the positive temperature coefficient thermistor is connected to the power supply potential. The overheat protection circuit is configured such that the switching transistor is turned on and off according to the voltage on the other end side of the positive temperature coefficient thermistor.
For example, the other end of the positive temperature coefficient thermistor is grounded via a voltage dividing resistor. The collector of the control transistor is connected to the gate of the switching transistor via a resistor, and the emitter of the control transistor is grounded via a reversely connected Zener diode. Further, the voltage divided by the voltage dividing resistor is applied to the base of the control transistor.
　このように構成された過熱保護回路においては、正特性サーミスタの温度が上昇すると、該正特性サーミスタによる降下電圧が大きくなり、スイッチングトランジスタがオフになる。スイッチングトランジスタがオフになった場合、負荷への給電が遮断される。逆に、正特性サーミスタの温度が低下すると、スイッチングトランジスタがオンになり、負荷への給電が再開される。 In the overheat protection circuit configured in this way, when the temperature of the positive temperature coefficient thermistor rises, the voltage drop due to the positive temperature coefficient thermistor increases and the switching transistor is turned off. When the switching transistor is turned off, the power supply to the load is cut off. On the contrary, when the temperature of the positive temperature coefficient thermistor decreases, the switching transistor is turned on, and the power supply to the load is resumed.
特開２００４－９６８０４号公報JP 2004-96804 A
　しかしながら、従来の過熱保護回路においては、電源電位が変動した場合、正特性サーミスタの他端側の電圧も変動してしまい、スイッチングトランジスタがオフになる正特性サーミスタの温度閾値が変化するという問題があった。車載バッテリを電源として用いた場合、オルタネーターによる発電時、エンジン始動時等、車載機器の動作時に電源電位が変動することがある。温度閾値が変化してしまうと、制御トランジスタが誤動作し、適切な過熱保護を行うことができない。 However, in the conventional overheat protection circuit, when the power supply potential fluctuates, the voltage on the other end side of the positive temperature coefficient thermistor also varies, and the temperature threshold value of the positive temperature coefficient thermistor that turns off the switching transistor changes. there were. When an in-vehicle battery is used as a power source, the power supply potential may fluctuate during operation of the in-vehicle device, such as during power generation by an alternator or when starting an engine. If the temperature threshold value changes, the control transistor malfunctions and appropriate overheat protection cannot be performed.
　本発明は斯かる事情に鑑みてなされたものであり、負荷への給電をオンオフするスイッチ又は該負荷への給電によって発熱する発熱部を、電源電位の変動に影響されること無く適切に保護することができる過熱保護装置を提供することにある。 The present invention has been made in view of such circumstances, and appropriately protects a switch for turning on and off the power supply to the load or a heat generating portion that generates heat by the power supply to the load without being affected by fluctuations in the power supply potential. An object of the present invention is to provide an overheat protection device that can be used.
　本発明に係る過熱保護装置は、負荷への給電をオンオフするスイッチと、該負荷への給電によって発熱する発熱部又は該スイッチに熱結合した感熱抵抗器と、該感熱抵抗器に定電流を供給する定電流回路と、前記感熱抵抗器の両端の電位差に応じて、前記スイッチをオフにする制御回路とを備えることを特徴とする。 An overheat protection device according to the present invention includes a switch for turning on and off power supply to a load, a heat generating part that generates heat by power supply to the load, or a thermal resistor thermally coupled to the switch, and supplies a constant current to the thermal resistor. And a control circuit for turning off the switch in accordance with a potential difference between both ends of the thermal resistor.
　感熱抵抗器は、発熱部又はスイッチに熱結合しているため、該発熱部又はスイッチの温度に応答して、感熱抵抗器の温度も変化する。感熱抵抗器には定電流が供給されているため、感熱抵抗器の温度と、該感熱抵抗器の両端の電位差との関係は、電源電位によって変動することは無い。制御回路は、感熱抵抗器の両端の電位差に応じて、スイッチをオフにする。
　従って、電源電位の電圧変動に影響されること無く、発熱部及びスイッチの温度に応じて、前記スイッチはオフになり、負荷への給電が遮断される。 Since the thermal resistor is thermally coupled to the heat generating part or the switch, the temperature of the thermal resistor also changes in response to the temperature of the heat generating part or the switch. Since a constant current is supplied to the thermal resistor, the relationship between the temperature of the thermal resistor and the potential difference between both ends of the thermal resistor does not vary depending on the power supply potential. The control circuit turns off the switch according to the potential difference between both ends of the thermal resistor.
Therefore, the switch is turned off according to the temperature of the heat generating part and the switch without being affected by the voltage fluctuation of the power supply potential, and the power supply to the load is cut off.
　本発明に係る過熱保護装置は、前記制御回路は、ソースが前記感熱抵抗器の高電位側に接続され、ゲートが前記感熱抵抗器の低電位側に接続されたＦＥＴを備えることを特徴とする。 The overheat protection device according to the present invention is characterized in that the control circuit includes an FET having a source connected to a high potential side of the thermal resistor and a gate connected to a low potential side of the thermal resistor. .
　ＦＥＴ（Field Effect Transistor）がオンオフする閾値電圧は、ソースの電位が高くなれば上昇し、ソースの電位が低くなれば降下する。ＦＥＴのソースは感熱抵抗器の高電位側に接続されているため、感熱抵抗器の高電位側の電圧が変動した場合、該電圧の変動に応じて、ＦＥＴがオンオフする閾値電圧も追随して変動する。従って、前記ＦＥＴは、感熱抵抗器の高電位側の電圧変動に拘わらず、感熱抵抗器の降下電圧に応じてオンオフする。 The threshold voltage at which FET (Field Effect Transistor) is turned on / off increases when the source potential increases and decreases when the source potential decreases. Since the source of the FET is connected to the high potential side of the thermal resistor, when the voltage on the high potential side of the thermal resistor fluctuates, the threshold voltage at which the FET turns on and off also follows the fluctuation of the voltage. fluctuate. Therefore, the FET is turned on / off according to the voltage drop of the thermal resistor regardless of the voltage fluctuation on the high potential side of the thermal resistor.
　本発明に係る過熱保護装置は、前記ＦＥＴはＰチャンネル型ＭＯＳＦＥＴ又はＮチャンネル接合型ＦＥＴであることを特徴とする。 The overheat protection device according to the present invention is characterized in that the FET is a P-channel MOSFET or an N-channel junction FET.
　Ｐチャンネル型ＭＯＳＦＥＴ（Metal Oxide Semiconductor Field Effect Transistor）は、感熱抵抗器の高電位側の電圧変動に拘わらず、感熱抵抗器の降下電圧に応じてオンオフする。
　同様に、Ｎチャンネル接合型ＦＥＴは、感熱抵抗器の高電位側の電圧変動に拘わらず、感熱抵抗器の降下電圧に応じてオンオフする。 A P-channel type MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is turned on and off in accordance with the voltage drop of the thermal resistor regardless of voltage fluctuation on the high potential side of the thermal resistor.
Similarly, the N-channel junction FET is turned on / off according to the voltage drop of the thermal resistor regardless of the voltage fluctuation on the high potential side of the thermal resistor.
　本発明に係る過熱保護装置は、前記感熱抵抗器は正特性サーミスタであり、前記制御回路は、一端子が前記スイッチのゲートに接続され、オンオフ用端子が前記Ｐチャンネル型ＭＯＳＦＥＴ又はＮチャンネル接合型ＦＥＴのドレインに接続され、他端子が接地されたトランジスタを備えることを特徴とする。 In the overheat protection device according to the present invention, the thermal resistor is a positive temperature coefficient thermistor, and the control circuit has one terminal connected to the gate of the switch and an on / off terminal connected to the P-channel MOSFET or N-channel junction type. A transistor is connected to the drain of the FET and the other terminal is grounded.
　前記Ｐチャンネル型ＭＯＳＦＥＴ及びトランジスタは、感熱抵抗器の温度が所定の温度以上になった場合、オンになり、前記スイッチはオフになる。つまり、負荷への給電が遮断される。
　同様に、前記Ｎチャンネル接合型ＦＥＴは、感熱抵抗器の温度が所定の温度以上になった場合、オンになり、前記スイッチはオフになる。つまり、負荷への給電が遮断される。 The P-channel MOSFET and the transistor are turned on and the switch is turned off when the temperature of the thermal resistor exceeds a predetermined temperature. That is, the power supply to the load is interrupted.
Similarly, the N-channel junction FET is turned on and the switch is turned off when the temperature of the thermal resistor exceeds a predetermined temperature. That is, the power supply to the load is interrupted.
　本発明に係る過熱保護装置は、前記感熱抵抗器は、電気的に前記スイッチに接続されていることを特徴とする。 The overheat protection device according to the present invention is characterized in that the thermal resistor is electrically connected to the switch.
　感熱抵抗器は、前記スイッチに電気的に接続されて熱結合している。従って、スイッチの熱は感熱抵抗器へ直ちに伝達される。 The thermal resistor is electrically connected to the switch and thermally coupled. Thus, the heat of the switch is immediately transferred to the thermal resistor.
　本発明にあっては、負荷への給電をオンオフするスイッチ又は該負荷への給電によって発熱する発熱部を、電源電位の変動に影響されること無く適切に保護することができる。 In the present invention, the switch for turning on / off the power supply to the load or the heat generating part that generates heat by the power supply to the load can be appropriately protected without being affected by the fluctuation of the power supply potential.
過熱保護装置の構成を概念的に示した回路ブロック図である。It is the circuit block diagram which showed notionally the structure of the overheat protection apparatus. 過熱保護装置の一構成例を示した回路図である。It is the circuit diagram which showed one structural example of the overheat protection apparatus.
　以下、本発明をその実施の形態を示す図面に基づいて詳述する。
　図１は過熱保護装置の構成を概念的に示した回路ブロック図、図２は過熱保護装置の一構成例を示した回路図である。過熱保護装置は、電源１、スイッチ２、負荷３、感熱抵抗器４、定電流回路５及び制御回路６を備える。過熱保護装置は、例えば車両に搭載されている。 Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.
FIG. 1 is a circuit block diagram conceptually showing the configuration of the overheat protection device, and FIG. 2 is a circuit diagram showing a configuration example of the overheat protection device. The overheat protection device includes a power source 1, a switch 2, a load 3, a thermal resistor 4, a constant current circuit 5 and a control circuit 6. The overheat protection device is mounted on a vehicle, for example.
　電源１は、例えば、鉛蓄電池、リチウムイオン電池等の車載バッテリである。鉛蓄電池は、正極板及び負極板と電解液とを備える。電源１の正極はスイッチ２を介して負荷３に接続されており、電源１は化学反応によって電力を負荷３へ供給する。なお、鉛蓄電池、リチウムイオン電池は、電源１の一例であり、負荷３に対して、必要な電力を供給できるものであれば、特にこれらに限定されない。 The power source 1 is, for example, a vehicle battery such as a lead storage battery or a lithium ion battery. The lead acid battery includes a positive electrode plate, a negative electrode plate, and an electrolytic solution. The positive electrode of the power source 1 is connected to the load 3 via the switch 2, and the power source 1 supplies power to the load 3 by a chemical reaction. The lead storage battery and the lithium ion battery are examples of the power source 1 and are not particularly limited as long as they can supply necessary power to the load 3.
　スイッチ２は、負荷３への給電をオンオフする素子である。スイッチ２は負荷３への給電によって発熱する素子である。スイッチ２は、本実施の形態における過熱保護装置の保護対象である。スイッチ２は、例えばＮチャンネル型のＭＯＳＦＥＴである。スイッチ２のドレインは電源１の正極に接続され、ソースは負荷３の一端に接続されている。スイッチ２のゲートは制御回路６に接続されている。スイッチ２は、制御回路６からの制御信号に応じて、オンオフする。具体的には、制御回路６からハイレベルの信号が、スイッチ２のゲートに印加された場合、スイッチ２はオンになり、ローレベルの信号がスイッチ２のゲートに印加された場合、スイッチ２はオフになる。
　なお、Ｎチャンネル型のＭＯＳＦＥＴは、スイッチ２の一例である。スイッチ２は、Ｐチャンネル型のＭＯＳＦＥＴ、接合型ＦＥＴ、バイポーラトランジスタ等の半導体スイッチであっても良いし、機械式スイッチであっても良い。 The switch 2 is an element that turns on and off the power supply to the load 3. The switch 2 is an element that generates heat when power is supplied to the load 3. The switch 2 is a protection target of the overheat protection device in the present embodiment. The switch 2 is, for example, an N channel type MOSFET. The drain of the switch 2 is connected to the positive electrode of the power source 1, and the source is connected to one end of the load 3. The gate of the switch 2 is connected to the control circuit 6. The switch 2 is turned on / off in response to a control signal from the control circuit 6. Specifically, when a high level signal is applied from the control circuit 6 to the gate of the switch 2, the switch 2 is turned on, and when a low level signal is applied to the gate of the switch 2, the switch 2 is Turn off.
Note that the N-channel MOSFET is an example of the switch 2. The switch 2 may be a semiconductor switch such as a P-channel MOSFET, a junction FET, or a bipolar transistor, or may be a mechanical switch.
　負荷３は、車両に搭載されたヘッドランプ、送風用モータ、各種駆動用のモータ等の装置である。負荷３の一端部は、スイッチ２のソース又は感熱抵抗器４の一端部に接続され、負荷３の他端部は接地されている。つまり、負荷３の他端部は車両の金属フレームに接続されている。 The load 3 is a device such as a headlamp, a blower motor, and various drive motors mounted on the vehicle. One end of the load 3 is connected to the source of the switch 2 or one end of the thermal resistor 4, and the other end of the load 3 is grounded. That is, the other end of the load 3 is connected to the metal frame of the vehicle.
　感熱抵抗器４は正特性サーミスタである。正特性サーミスタは、温度が上昇すると、抵抗値が増加する抵抗器である。感熱抵抗器４の一端部はスイッチ２のソースに電気的に接続して熱結合している。つまり、電源１からの電流はスイッチ２を通じて感熱抵抗器４に流れると共に、通電によって発熱したスイッチ２の熱が感熱抵抗器４に伝導するように構成されている。より具体的には、スイッチ２が配された回路基板の導電線に対して感熱抵抗器４の一端部を直接的に接続してある。また感熱抵抗器４の他端部は定電流回路５に接続されている。 The thermal resistor 4 is a positive temperature coefficient thermistor. The positive temperature coefficient thermistor is a resistor whose resistance value increases as the temperature rises. One end of the thermal resistor 4 is electrically connected to and thermally coupled to the source of the switch 2. That is, the current from the power source 1 flows to the thermal resistor 4 through the switch 2, and the heat of the switch 2 generated by energization is conducted to the thermal resistor 4. More specifically, one end of the thermal resistor 4 is directly connected to the conductive wire of the circuit board on which the switch 2 is arranged. The other end of the thermal resistor 4 is connected to the constant current circuit 5.
　定電流回路５は、感熱抵抗器４及び該定電流回路５に印加される電圧に拘わらず、感熱抵抗器４に定電流を供給する回路である。定電流の大きさは後述する。 The constant current circuit 5 is a circuit that supplies a constant current to the thermal resistor 4 regardless of the voltage applied to the thermal resistor 4 and the constant current circuit 5. The magnitude of the constant current will be described later.
　制御回路６は、感熱抵抗器４の両端の電位差に応じて、スイッチ２をオフにする回路である。具体的には、制御回路６はスイッチ２のオンオフを制御する制御部６１と、スイッチ２の過熱時に該スイッチ２を強制的に遮断制御するためのＰチャンネル型ＭＯＳＦＥＴ６２及びトランジスタ６３を備える。 The control circuit 6 is a circuit that turns off the switch 2 in accordance with the potential difference between both ends of the thermal resistor 4. Specifically, the control circuit 6 includes a control unit 61 that controls on / off of the switch 2, and a P-channel MOSFET 62 and a transistor 63 for forcibly controlling the switch 2 when the switch 2 is overheated.
　制御部６１は、例えばＣＰＵ、ＲＯＭ、ＲＡＭ、制御信号出力部、ＣＡＮ通信インタフェース、Ｉ／Ｏポート等を備えたマイコンである。ＣＡＮ通信インタフェースには図示しない外部の電子制御装置（ECU：Electronic Control Unit）がＣＡＮを介して接続されている。制御信号出力部は、スイッチ２のゲートが接続されている。制御部６１は、図示しない外部の電子制御装置から、負荷３への給電指令を受けた場合、制御部６１は制御信号出力部からハイレベルの制御信号を出力する。スイッチ２のゲートにハイレベルの制御信号を印加することによって、スイッチ２をオンにし、負荷３へ給電することができる。前記電子制御装置から負荷３への給電停止命令を受けた場合、制御部６１は制御信号出力部からローレベルの制御信号を出力する。スイッチ２のゲートにローレベルの制御信号を印加することによって、スイッチ２をオフにし、負荷３への給電を停止することができる。 The control unit 61 is a microcomputer including, for example, a CPU, a ROM, a RAM, a control signal output unit, a CAN communication interface, an I / O port, and the like. An external electronic control unit (ECU: Electronic Control Unit) (not shown) is connected to the CAN communication interface via the CAN. The control signal output unit is connected to the gate of the switch 2. When the control unit 61 receives a power supply command to the load 3 from an external electronic control device (not shown), the control unit 61 outputs a high-level control signal from the control signal output unit. By applying a high level control signal to the gate of the switch 2, the switch 2 can be turned on and power can be supplied to the load 3. When receiving a power supply stop command to the load 3 from the electronic control unit, the control unit 61 outputs a low-level control signal from the control signal output unit. By applying a low-level control signal to the gate of the switch 2, the switch 2 can be turned off and the power supply to the load 3 can be stopped.
　Ｐチャンネル型ＭＯＳＦＥＴ６２のソースは、スイッチ２のソースと、感熱抵抗器４の前記一端部とに接続されている。つまり、Ｐチャンネル型ＭＯＳＦＥＴ６２のソースは、スイッチ２のソースと、感熱抵抗器４の高電位側とに接続されている。また、Ｐチャンネル型ＭＯＳＦＥＴ６２のゲートは、感熱抵抗器４の他端部、つまり低電位側の端部に接続されている。Ｐチャンネル型ＭＯＳＦＥＴ６２のドレインは、トランジスタ６３のベースに接続されている。
　なお、Ｐチャンネル型ＭＯＳＦＥＴ６２に代えて、Ｎチャンネル接合型ＦＥＴを用いても良い。 The source of the P-channel type MOSFET 62 is connected to the source of the switch 2 and the one end of the thermal resistor 4. That is, the source of the P-channel MOSFET 62 is connected to the source of the switch 2 and the high potential side of the thermal resistor 4. The gate of the P-channel type MOSFET 62 is connected to the other end of the thermal resistor 4, that is, the end on the low potential side. The drain of the P-channel type MOSFET 62 is connected to the base of the transistor 63.
Instead of the P channel type MOSFET 62, an N channel junction type FET may be used.
　トランジスタ６３は、例えばバイポーラトランジスタである。トランジスタ６３のコレクタがスイッチ２のゲート及び制御部６１の制御信号出力部に接続されている。トランジスタ６３のエミッタは接地されている。なお、バイポーラトランジスタは、トランジスタ６３の一例であり、Ｎチャンネル型のＭＯＳＦＥＴ、Ｐチャンネル型の接合型ＦＥＴ等で構成しても良い。 The transistor 63 is, for example, a bipolar transistor. The collector of the transistor 63 is connected to the gate of the switch 2 and the control signal output unit of the control unit 61. The emitter of the transistor 63 is grounded. Note that the bipolar transistor is an example of the transistor 63, and may be composed of an N-channel MOSFET, a P-channel junction FET, or the like.
　このように構成された過熱保護装置の動作を説明する。
　感熱抵抗器４による降下電圧は下記式（１）で表される。 The operation of the overheat protection device configured as described above will be described.
The voltage drop due to the thermal resistor 4 is expressed by the following formula (1).
Figure JPOXMLDOC01-appb-M000001
  
Figure JPOXMLDOC01-appb-M000001
  
　Ｐチャンネル型ＭＯＳＦＥＴ６２がオンになる条件は下記式（２）で表される。 The condition for turning on the P-channel MOSFET 62 is expressed by the following equation (2).
Figure JPOXMLDOC01-appb-M000002
  
Figure JPOXMLDOC01-appb-M000002
  
　上記式（２）の左辺はＰチャンネル型ＭＯＳＦＥＴ６２のゲートに印加される電圧を示しており、右辺はＰチャンネル型ＭＯＳＦＥＴ６２がオンになるゲート電圧を示している。
　上記式（２）は下記式（３）に変形できる。 The left side of the above formula (2) indicates the voltage applied to the gate of the P-channel MOSFET 62, and the right side indicates the gate voltage at which the P-channel MOSFET 62 is turned on.
The above equation (2) can be transformed into the following equation (3).
Figure JPOXMLDOC01-appb-M000003
  
Figure JPOXMLDOC01-appb-M000003
  
　上記式（３）から分かるように、Ｐチャンネル型ＭＯＳＦＥＴ６２がオンになるゲート電圧は、電源電位に依存せず、Ｐチャンネル型ＭＯＳＦＥＴ６２のソースドレイン間の閾値電圧によって決まる。
　従って、Ｐチャンネル型ＭＯＳＦＥＴ６２は、電源電位に依存せず、感熱抵抗器４の降下電圧が前記閾値電圧よりより大きい場合、オンになる。感熱抵抗器４の降下電圧が前記閾値電圧以下である場合、Ｐチャンネル型ＭＯＳＦＥＴ６２は、オフになる。つまり、Ｐチャンネル型ＭＯＳＦＥＴ６２は、正特性サーミスタである感熱抵抗器４の温度が高い場合、オンになり、感熱抵抗器４の温度が低い場合オフになる。 As can be seen from the above equation (3), the gate voltage at which the P-channel MOSFET 62 is turned on does not depend on the power supply potential, but is determined by the threshold voltage between the source and drain of the P-channel MOSFET 62.
Therefore, the P-channel type MOSFET 62 does not depend on the power supply potential, and is turned on when the voltage drop across the thermal resistor 4 is greater than the threshold voltage. When the voltage drop across the thermal resistor 4 is less than or equal to the threshold voltage, the P-channel MOSFET 62 is turned off. That is, the P-channel MOSFET 62 is turned on when the temperature of the thermal resistor 4 that is a positive temperature coefficient thermistor is high, and turned off when the temperature of the thermal resistor 4 is low.
　感熱抵抗器４の温度が低く、Ｐチャンネル型ＭＯＳＦＥＴ６２がオフ状態である場合、トランジスタ６３はオフ状態である。トランジスタ６３がオフ状態である場合、制御部６１から出力される制御信号に従って、スイッチ２はオンオフする。
　感熱抵抗器４の温度が高く、Ｐチャンネル型ＭＯＳＦＥＴ６２がオン状態である場合、トランジスタ６３はオン状態である。トランジスタ６３がオン状態である場合、スイッチ２のゲートは接地されるため、制御部６１からハイレベルの制御信号が出力されていても、スイッチ２はオフになり、負荷３への給電が遮断される。 When the temperature of the thermal resistor 4 is low and the P-channel MOSFET 62 is off, the transistor 63 is off. When the transistor 63 is in the off state, the switch 2 is turned on and off in accordance with the control signal output from the control unit 61.
When the temperature of the thermal resistor 4 is high and the P-channel MOSFET 62 is on, the transistor 63 is on. When the transistor 63 is in the ON state, the gate of the switch 2 is grounded. Therefore, even if a high level control signal is output from the control unit 61, the switch 2 is turned off and the power supply to the load 3 is cut off. The
　次に、スイッチ２をオフにする閾値の決定方法を説明する。上記式（１）及び（３）より、下記式（４）が得られる。 Next, a method for determining a threshold value for turning off the switch 2 will be described. From the above formulas (1) and (3), the following formula (4) is obtained.
Figure JPOXMLDOC01-appb-M000004
  
Figure JPOXMLDOC01-appb-M000004
  
　ここで、スイッチ２をオフにする閾値温度における感熱抵抗器４の抵抗値は既知であるため、上記式（４）より、定電流回路５によって供給すべき定電流の値は下記式（５）で与えられる。 Here, since the resistance value of the thermal resistor 4 at the threshold temperature at which the switch 2 is turned off is known, the constant current value to be supplied by the constant current circuit 5 is represented by the following formula (5) from the above formula (4). Given in.
Figure JPOXMLDOC01-appb-M000005
  
Figure JPOXMLDOC01-appb-M000005
  
　このように構成された過熱保護回路によれば、電源電位の変動に影響されること無く、スイッチ２が閾値温度以上にならないように保護することができる。 The overheat protection circuit configured in this way can protect the switch 2 from exceeding the threshold temperature without being affected by fluctuations in the power supply potential.
　また、感熱抵抗器４はスイッチ２に対して電気的に接続されて熱結合しているため、過熱保護回路の熱応答性を向上させることができる。つまり、スイッチ２の温度上昇に追随して、感熱抵抗器４の温度も直ちに上昇するため、スイッチ２が閾値電圧に達した場合、速やかにスイッチ２をオフにすることができ、スイッチ２を過熱から効果的に保護することができる。 Further, since the thermal resistor 4 is electrically connected to the switch 2 and thermally coupled, the thermal responsiveness of the overheat protection circuit can be improved. That is, the temperature of the thermal resistor 4 immediately rises following the rise in the temperature of the switch 2, so that when the switch 2 reaches the threshold voltage, the switch 2 can be quickly turned off and the switch 2 is overheated. Can be effectively protected from.
　更に、スイッチ２の過熱保護制御を、制御回路６のＰチャンネル型ＭＯＳＦＥＴ６２及びトランジスタ６３によって実現している。従って、過熱保護装置は、過熱に対する応答性に優れており、制御部６１の処理負担を軽減させることができる。 Further, overheat protection control of the switch 2 is realized by the P-channel type MOSFET 62 and the transistor 63 of the control circuit 6. Therefore, the overheat protection device has excellent responsiveness to overheating, and can reduce the processing load on the control unit 61.
　なお、本実施の形態では、過熱保護制御を行う回路を、Ｐチャンネル型ＭＯＳＦＥＴ６２及びトランジスタ６３で構成する例を説明したが、感熱抵抗器４の降下電圧に応じて、スイッチ２をオンオフ制御できる構成であれば、特に本実施の形態の構成に限定されない。
　例えば、トランジスタ６３を廃し、制御部６１がＰチャンネル型ＭＯＳＦＥＴ６２のドレイン電圧に応じて、スイッチ２をオンオフ制御するように構成しても良い。より具体的には、Ｐチャンネル型ＭＯＳＦＥＴ６２のドレイン電圧を、分圧抵抗で分圧し、分圧された電圧を制御部６１のＩ／Ｏポートに入力するように構成すると良い。制御部６１は、所定の閾値電圧より高い場合、スイッチ２を強制的にオフにする制御を行う。この場合、Ｐチャンネル型ＭＯＳＦＥＴ６２は、Ｎチャンネル型ＭＯＳＦＥＴで構成しても良いし、Ｐチャンネル型又はＮチャンネル型の接合型ＦＥＴで構成しても良い。
　また、感熱抵抗器４の一端部の電圧値と、他端部の電圧値とを制御部６１がＩ／Ｏポートを介して取得し、取得した電圧値の差分に応じて、スイッチ２をオンオフ制御するように構成しても良い。感熱抵抗器４が熱に対して正特性を有する場合、前記差分が閾値より大きいときに、スイッチ２を強制的にオフ制御すれば良い。感熱抵抗器４が負特性を有する場合、前記差分が閾値より小さいときに、スイッチ２を強制的にオフ制御すれば良い。 In this embodiment, an example in which the circuit for performing the overheat protection control is configured by the P-channel MOSFET 62 and the transistor 63 has been described. However, the switch 2 can be controlled to be turned on / off according to the voltage drop of the thermal resistor 4. If it is, it will not be limited to the structure of this Embodiment in particular.
For example, the transistor 63 may be eliminated, and the control unit 61 may be configured to perform on / off control of the switch 2 in accordance with the drain voltage of the P-channel MOSFET 62. More specifically, the drain voltage of the P-channel MOSFET 62 may be divided by a voltage dividing resistor, and the divided voltage may be input to the I / O port of the control unit 61. The control unit 61 performs control to forcibly turn off the switch 2 when higher than a predetermined threshold voltage. In this case, the P-channel MOSFET 62 may be composed of an N-channel MOSFET or a P-channel or N-channel junction FET.
Further, the control unit 61 acquires the voltage value at one end of the thermal resistor 4 and the voltage value at the other end via the I / O port, and the switch 2 is turned on / off according to the difference between the acquired voltage values. You may comprise so that it may control. When the thermal resistor 4 has a positive characteristic with respect to heat, the switch 2 may be forcibly turned off when the difference is larger than a threshold value. When the thermal resistor 4 has a negative characteristic, the switch 2 may be forcibly turned off when the difference is smaller than the threshold value.
　また、感熱抵抗器４として正特性サーミスタを例示したが、温度によって抵抗値が変化する素子であれば、正特性サーミスタに限定されない。例えば、白銀測温抵抗体を感熱抵抗器４として用いても良い。また、上述したように、制御回路６の構成によっては、感熱抵抗器４は正特性である必要は無く、負特性の感熱抵抗器４、例えば負特性サーミスタで構成しても良い。負特性サーミスタは、温度が上昇すると、抵抗値が低下する抵抗器である。
　例えば、トランジスタ６３のコレクタをスイッチ２のゲートに接続し、トランジスタ６３のエミッタを制御信号出力部に接続し、ベースをＰチャンネル型ＭＯＳＦＥＴ６２のドレインに接続すると良い。感熱抵抗器４が負特性であるため、スイッチ２が閾値温度以下である場合、Ｐチャンネル型ＭＯＳＦＥＴ６２がオンになり、制御信号出力とスイッチ２のゲートとが接続される。スイッチ２が閾値温度未満である場合、Ｐチャンネル型ＭＯＳＦＥＴ６２がオフになり、制御信号出力とスイッチ２のゲートとが切断され、負荷３への給電が遮断される。 Moreover, although the positive temperature coefficient thermistor was illustrated as the thermal resistor 4, if it is an element from which resistance value changes with temperature, it is not limited to a positive temperature coefficient thermistor. For example, a silver temperature measuring resistor may be used as the thermal resistor 4. Further, as described above, depending on the configuration of the control circuit 6, the thermal resistor 4 does not have to have a positive characteristic, and may be configured by a negative thermal resistor 4, for example, a negative characteristic thermistor. The negative characteristic thermistor is a resistor whose resistance value decreases as the temperature rises.
For example, the collector of the transistor 63 is connected to the gate of the switch 2, the emitter of the transistor 63 is connected to the control signal output unit, and the base is connected to the drain of the P-channel MOSFET 62. Since the thermal resistor 4 has a negative characteristic, when the switch 2 is below the threshold temperature, the P-channel MOSFET 62 is turned on, and the control signal output and the gate of the switch 2 are connected. When the switch 2 is lower than the threshold temperature, the P-channel MOSFET 62 is turned off, the control signal output and the gate of the switch 2 are disconnected, and the power supply to the load 3 is cut off.
　更に、本実施の形態では、スイッチ２を過熱から保護する例を説明したが、負荷への給電によって過熱される任意の過熱部の温度を、感熱抵抗器４によって検知し、負荷への給電を遮断するように構成しても良い。 Furthermore, in the present embodiment, an example in which the switch 2 is protected from overheating has been described. However, the temperature of an arbitrary overheated portion that is overheated by power supply to the load is detected by the thermal resistor 4 to supply power to the load. You may comprise so that it may interrupt | block.
　今回開示された実施の形態はすべての点で例示であって、制限的なものでは無いと考えられるべきである。本発明の範囲は、上で例示した内容だけで無く、請求の範囲によって示され、請求の範囲と均等の意味及び範囲内でのすべての更新が含まれることが意図される。 It should be considered that the embodiment disclosed this time is illustrative in all respects and not restrictive. The scope of the present invention is shown not only by the contents exemplified above but also by the scope of claims, and is intended to include meanings equivalent to the scope of claims and all updates within the scope.
　１　電源
　２　スイッチ
　３　負荷
　４　感熱抵抗器
　５　定電流回路
　６　制御回路
　６１　制御部
　６２　Ｐチャンネル型ＭＯＳＦＥＴ
　６３　トランジスタ
  DESCRIPTION OF SYMBOLS 1 Power supply 2 Switch 3 Load 4 Thermal resistor 5 Constant current circuit 6 Control circuit 61 Control part 62 P channel type MOSFET
63 transistors

Claims (5)

  1. 　負荷への給電をオンオフするスイッチと、該負荷への給電によって発熱する発熱部又は該スイッチに熱結合した感熱抵抗器と、
    　該感熱抵抗器に定電流を供給する定電流回路と、
    　前記感熱抵抗器の両端の電位差に応じて、前記スイッチをオフにする制御回路と
    　を備えることを特徴とする過熱保護装置。     A switch for turning on / off the power supply to the load, a heat generating part that generates heat by the power supply to the load, or a thermal resistor thermally coupled to the switch,
    A constant current circuit for supplying a constant current to the thermal resistor;
    And a control circuit that turns off the switch in accordance with a potential difference between both ends of the thermal resistor.
  2. 　前記制御回路は、
    　ソースが前記感熱抵抗器の高電位側に接続され、ゲートが前記感熱抵抗器の低電位側に接続されたＦＥＴを備える
    　ことを特徴とする請求項１に記載の過熱保護装置。     The control circuit includes:
    The overheat protection device according to claim 1, further comprising: an FET having a source connected to a high potential side of the thermal resistor and a gate connected to a low potential side of the thermal resistor.
  3. 　前記ＦＥＴはＰチャンネル型ＭＯＳＦＥＴ又はＮチャンネル接合型ＦＥＴである
    　ことを特徴とする請求項２に記載の過熱保護装置。     The overheat protection device according to claim 2, wherein the FET is a P-channel MOSFET or an N-channel junction FET.
  4. 　前記感熱抵抗器は正特性サーミスタであり、
    　前記制御回路は、
    　一端子が前記スイッチのゲートに接続され、オンオフ用端子が前記Ｐチャンネル型ＭＯＳＦＥＴ又はＮチャンネル接合型ＦＥＴのドレインに接続され、他端子が接地されたトランジスタを備える
    　ことを特徴とする請求項３に記載の過熱保護装置。     The thermal resistor is a positive temperature coefficient thermistor,
    The control circuit includes:
    4. The transistor according to claim 3, further comprising: a transistor having one terminal connected to the gate of the switch, an on / off terminal connected to the drain of the P-channel MOSFET or N-channel junction FET, and the other terminal grounded. The overheat protection device described.
  5. 　前記感熱抵抗器は、電気的に前記スイッチに接続されている
    　ことを特徴とする請求項１から請求項４のいずれか一つに記載の過熱保護装置。
          The overheat protection device according to any one of claims 1 to 4, wherein the thermal resistor is electrically connected to the switch.
PCT/JP2014/075782 2013-10-10 2014-09-29 Overheating protector WO2015053106A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2013-213207 2013-10-10
JP2013213207A JP2015077030A (en) 2013-10-10 2013-10-10 Overheat protection device

Publications (1)

Publication Number Publication Date
WO2015053106A1 true WO2015053106A1 (en) 2015-04-16

Family

ID=52812925

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2014/075782 WO2015053106A1 (en) 2013-10-10 2014-09-29 Overheating protector

Country Status (2)

Country Link
JP (1) JP2015077030A (en)
WO (1) WO2015053106A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11395358B2 (en) 2014-01-31 2022-07-19 Sony Corporation Communications device

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6569693B2 (en) * 2017-02-10 2019-09-04 サンケン電気株式会社 Electronic circuit and overheat detection method

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004096804A (en) * 2002-08-29 2004-03-25 Murata Mfg Co Ltd Overheat protective circuit
WO2008004445A1 (en) * 2006-07-06 2008-01-10 Panasonic Corporation Protecting apparatus, and protecting method, signal processing method and electrical quantity detecting method employed by the protecting apparatus

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004096804A (en) * 2002-08-29 2004-03-25 Murata Mfg Co Ltd Overheat protective circuit
WO2008004445A1 (en) * 2006-07-06 2008-01-10 Panasonic Corporation Protecting apparatus, and protecting method, signal processing method and electrical quantity detecting method employed by the protecting apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11395358B2 (en) 2014-01-31 2022-07-19 Sony Corporation Communications device

Also Published As

Publication number Publication date
JP2015077030A (en) 2015-04-20

Similar Documents

Publication Publication Date Title
JP5189929B2 (en) Semiconductor switch control device
CN104682792B (en) Direct current motor control circuit
JP4929020B2 (en) Overcurrent protection device for load circuit
US11038371B2 (en) Power supply control device
JP6472076B2 (en) Load current control device
KR101972604B1 (en) Semiconductor device
JP2007159159A (en) Protection device of semiconductor device
EP2937960A1 (en) Method for automatically blocking high temperature/high current to which mit technology is applied and switch using same
CN108292917B (en) Circuit arrangement for temperature-dependent actuation of a switching element
US8730635B2 (en) Power supply controller
WO2015053106A1 (en) Overheating protector
JP2010104079A (en) Load driver
JP4263685B2 (en) Protection circuit
JP6324696B2 (en) LOAD DRIVE DEVICE, VEHICLE AIR CONDITIONER INCLUDING THE SAME, AND LOAD SHORT PROTECTION CIRCUIT
JP2010193033A (en) Overcurrent protection circuit
JP2009240136A (en) Device and method for controlling motor
JP5325437B2 (en) Integrated circuit
JP5776946B2 (en) Power supply control device
JP2012207976A (en) Current detection device, overcurrent protective device and current detection method
US10707676B2 (en) Electric wire protection device
US10599198B2 (en) Load driving device
EP2843824B1 (en) Electronic control circuitry with start up capability
JP2010104138A (en) Dc motor driver
JP6379294B2 (en) Electrical circuit device
JP7127736B2 (en) Current detection device and power supply control device

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 14851760

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 14851760

Country of ref document: EP

Kind code of ref document: A1