JP2014115786A - Current control apparatus and control system - Google Patents

Current control apparatus and control system Download PDF

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JP2014115786A
JP2014115786A JP2012268657A JP2012268657A JP2014115786A JP 2014115786 A JP2014115786 A JP 2014115786A JP 2012268657 A JP2012268657 A JP 2012268657A JP 2012268657 A JP2012268657 A JP 2012268657A JP 2014115786 A JP2014115786 A JP 2014115786A
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potential difference
load
switching element
shunt resistor
current
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JP5998895B2 (en
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Toshio Goto
敏夫 後藤
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Toyota Motor Corp
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Abstract

PROBLEM TO BE SOLVED: To provide a current control apparatus which prevents false detection of overcurrent.SOLUTION: A current control apparatus includes: a switching element 50 connected between a load 3 and a power source 4; a shunt resistor 40 connected between the switching element 50 and the power source 4; and a control part 30 which turns off the switching element 50 when a potential difference between both ends of the shunt resistor 40 is equal to or larger than a predetermined value. The control part 30 determines that measurement of the potential difference fails when the potential difference between both ends to be obtained after turning off the switching element 50 is equal to or larger than the predetermined value.

Description

本発明は、シャント抵抗の両端の電位差が所定値以上と計測された場合、トランジスタ等のスイッチング素子をオフにする技術に関する。   The present invention relates to a technique for turning off a switching element such as a transistor when a potential difference between both ends of a shunt resistor is measured to be a predetermined value or more.

例えば特許文献１には、シャント抵抗の両端の電位差が所定値以上と計測された場合、負荷と電源との間に設けられたトランジスタをオフにする回路が開示されている。   For example, Patent Document 1 discloses a circuit that turns off a transistor provided between a load and a power source when a potential difference between both ends of a shunt resistor is measured to be a predetermined value or more.

特開２０１０−２４４３６７号公報JP 2010-244367 A

しかしながら、上述の回路構成では、例えば、シャント抵抗の両端の電位差を計測するための端子のうち、負荷側の端子が外れると、過電流検知部に入力される電位差が大きくなり過電流を判定する閾値を超えてしまう。そのため、過電流が本当に流れたことによってトランジスタがオフになったのか、それ以外の原因によって過電流が誤検出されることによりトランジスタがオフになったのかが判別できない。   However, in the above-described circuit configuration, for example, when the load-side terminal out of the terminals for measuring the potential difference between both ends of the shunt resistor is disconnected, the potential difference input to the overcurrent detection unit becomes large and the overcurrent is determined. The threshold is exceeded. For this reason, it cannot be determined whether the transistor has been turned off due to the fact that the overcurrent has actually flown or whether the transistor has been turned off due to erroneous detection of the overcurrent due to other causes.

本発明は、過電流の誤検出を防止できる、電流制御装置及び制御システムの提供を目的とする。   An object of the present invention is to provide a current control device and a control system that can prevent erroneous detection of overcurrent.

上記目的を達成するため、本発明は、
負荷と電源との間に接続されるスイッチング素子と、
前記スイッチング素子と前記電源との間に接続されるシャント抵抗と、
前記シャント抵抗の両端の電位差が所定値以上と計測された場合、前記スイッチング素子をオフにする制御部とを有する、電流制御装置であって、
前記制御部は、前記スイッチング素子をオフにした後の前記両端の電位差が前記所定値以上と計測された場合、前記電位差の計測に異常があると判定することを特徴とする、電流制御装置を提供するものである。 In order to achieve the above object, the present invention provides:
A switching element connected between the load and the power source;
A shunt resistor connected between the switching element and the power source;
A current control device having a control unit for turning off the switching element when a potential difference between both ends of the shunt resistor is measured to be a predetermined value or more;
The control unit determines that the measurement of the potential difference is abnormal when the potential difference between the both ends after the switching element is turned off is measured to be equal to or greater than the predetermined value. It is to provide.

また、上記目的を達成するため、本発明は、
負荷と、前記負荷に流れる負荷電流を監視する電流制御装置とを備え、
前記電流制御装置は、
前記負荷と電源との間に接続されるスイッチング素子と、
前記スイッチング素子と前記電源との間に接続されるシャント抵抗と、
前記シャント抵抗の両端の電位差が所定値以上と計測された場合、前記スイッチング素子をオフにする制御部とを有し、
前記制御部は、前記スイッチング素子をオフにした後の前記両端の電位差が前記所定値以上と計測された場合、前記電位差の計測に異常があると判定し、前記スイッチング素子をオフにした後の前記両端の電位差が前記所定値未満と計測された場合、前記負荷に異常があると判定する、制御システムを提供するものである。 In order to achieve the above object, the present invention provides:
A load, and a current control device that monitors a load current flowing through the load,
The current controller is
A switching element connected between the load and a power source;
A shunt resistor connected between the switching element and the power source;
A control unit that turns off the switching element when a potential difference between both ends of the shunt resistor is measured to be a predetermined value or more;
The control unit determines that there is an abnormality in the measurement of the potential difference when the potential difference between the both ends after the switching element is turned off is greater than or equal to the predetermined value, and after the switching element is turned off. A control system for determining that the load is abnormal when the potential difference between the both ends is measured to be less than the predetermined value is provided.

本発明によれば、過電流の誤検出を防止できる。   According to the present invention, erroneous detection of overcurrent can be prevented.

一実施形態に係る制御システムのブロック図1 is a block diagram of a control system according to an embodiment. 負荷の過電流異常時の動作波形の一例Example of operation waveform when load overcurrent is abnormal 計測異常時の動作波形の一例Example of operation waveform when measurement is abnormal

図１は、自動車等の車両用の制御システム１の構成例を示した回路ブロック図である。制御システム１は、負荷３と、負荷３に流れる負荷電流を監視する電流制御装置２とを備えている。   FIG. 1 is a circuit block diagram showing a configuration example of a control system 1 for a vehicle such as an automobile. The control system 1 includes a load 3 and a current control device 2 that monitors a load current flowing through the load 3.

負荷３は、車両に搭載される任意の負荷である。その具体例として、ＥＣＵ（Electronic Control Unit）等の電子制御装置、モータ等のソレノイド負荷、抵抗負荷などが挙げられる。一方、電流制御装置２は、直流電源４と負荷３との間に配置され、負荷３に流れる負荷電流をシャント抵抗４０によって監視するＥＣＵ等の電子制御装置である。   The load 3 is an arbitrary load mounted on the vehicle. Specific examples thereof include an electronic control unit such as an ECU (Electronic Control Unit), a solenoid load such as a motor, and a resistance load. On the other hand, the current control device 2 is an electronic control device such as an ECU that is disposed between the DC power supply 4 and the load 3 and monitors the load current flowing through the load 3 by the shunt resistor 40.

このような制御システム１の典型的な具体例として、アイドリングストップシステムが挙げられる。アイドリングストップシステムでは、エコランＥＣＵがエンジンＥＣＵ等の他のＥＣＵの負荷電流を監視する機能を有している。例えば図１の場合、電流制御装置２がエコランＥＣＵに相当し、負荷３がエンジンＥＣＵ等の他のＥＣＵに相当する。   A typical example of such a control system 1 is an idling stop system. In the idling stop system, the eco-run ECU has a function of monitoring the load current of another ECU such as an engine ECU. For example, in the case of FIG. 1, the current control device 2 corresponds to an eco-run ECU, and the load 3 corresponds to another ECU such as an engine ECU.

エコランＥＣＵは、アイドリングストップ等の、燃料消費量の節減と二酸化炭素等の排出ガスの低減を目的とした車両走行、いわゆるエコランと呼ばれている走行方式を実行するためのエコラン制御を行うＥＣＵである。エコランＥＣＵは、車両停止時にエンジンを停止させるための指令をエンジンＥＣＵに送信し、車両走行開始時にエンジンを再始動させるための指令をエンジンＥＣＵに送信する。   The eco-run ECU is an ECU that performs eco-run control for executing a vehicle driving method called so-called “eco-run” for the purpose of reducing fuel consumption and reducing exhaust gas such as carbon dioxide, such as idling stop. is there. The eco-run ECU transmits a command for stopping the engine to the engine ECU when the vehicle stops, and transmits a command for restarting the engine to the engine ECU when the vehicle starts running.

電流制御装置２は、制御部３０とリレー用ＭＯＳ５０とを有している。制御部３０は、過電流検出回路１０及び制御回路２０を有している。   The current control device 2 includes a control unit 30 and a relay MOS 50. The control unit 30 includes an overcurrent detection circuit 10 and a control circuit 20.

過電流検出回路１０は、負荷３と直流電源４との間に直列に挿入されて接続されるシャント抵抗４０の両端の電位差を計測することによって、負荷３に流れる過剰な負荷電流（負荷過電流）を検出する過電流検出部である。過電流検出回路１０は、負荷過電流が検出された場合、負荷過電流が検出されたことを表す過電流検出信号ＶＣを出力する。   The overcurrent detection circuit 10 measures an excess load current flowing through the load 3 (load overcurrent) by measuring a potential difference between both ends of the shunt resistor 40 inserted and connected in series between the load 3 and the DC power supply 4. ) To detect an overcurrent. When a load overcurrent is detected, the overcurrent detection circuit 10 outputs an overcurrent detection signal VC indicating that the load overcurrent has been detected.

制御回路２０は、過電流検出信号ＶＣが過電流検出回路１０から出力された場合、リレー用ＭＯＳ５０をオフにする。そして、制御回路２０は、リレー用ＭＯＳ５０をオフにしてから所定時間経過後の過電流検出信号ＶＣをモニターする。制御回路２０は、リレー用ＭＯＳ５０をオフにした後の過電流検出信号ＶＣの有無によって、負荷３の異常によってリレー用ＭＯＳ５０をオフにしたのか、過電流検出回路１０の異常によってリレー用ＭＯＳ５０をオフにしたのかを区別できる。   When the overcurrent detection signal VC is output from the overcurrent detection circuit 10, the control circuit 20 turns off the relay MOS 50. The control circuit 20 monitors the overcurrent detection signal VC after a predetermined time has elapsed since the relay MOS 50 is turned off. The control circuit 20 turns off the relay MOS 50 due to an abnormality in the load 3 depending on the presence or absence of the overcurrent detection signal VC after the relay MOS 50 is turned off, or turns off the relay MOS 50 due to an abnormality in the overcurrent detection circuit 10 Can be distinguished.

図２は、負荷３の異常（負荷過電流）によって過電流検出信号ＶＣが出力されたときの動作波形であり、図３は、過電流検出回路１０の異常によって過電流検出信号ＶＣが出力されたときの動作波形である。   FIG. 2 is an operation waveform when the overcurrent detection signal VC is output due to an abnormality in the load 3 (load overcurrent). FIG. 3 illustrates the overcurrent detection signal VC output due to an abnormality in the overcurrent detection circuit 10. It is an operation waveform at the time.

負荷３に負荷過電流が流れる異常が発生すると（図２の場合）、シャント抵抗４０の両端の電位差がその負荷過電流に応じて上昇する。過電流検出回路１０は、シャント抵抗４０の両端の電位差が所定の過電流判定開始閾値以上とタイミングｔ１で計測された場合、過電流検出信号ＶＣの出力を開始する（例えば、過電流検出信号ＶＣのレベルがローレベルからハイレベルに変化）。   When an abnormality occurs in which the load overcurrent flows through the load 3 (in the case of FIG. 2), the potential difference between both ends of the shunt resistor 40 increases according to the load overcurrent. The overcurrent detection circuit 10 starts outputting the overcurrent detection signal VC when the potential difference between both ends of the shunt resistor 40 is measured at a timing t1 when the potential difference between the two ends of the shunt resistor 40 is equal to or greater than a predetermined overcurrent determination start threshold (for example, the overcurrent detection signal VC). Level changes from low to high).

制御回路２０のタイマー２１は、タイミングｔ１からの経過時間をカウントし、そのカウント値が所定の過電流検出閾値を超えると、リレー用ＭＯＳ５０をタイミングｔ２でオフにする。リレー用ＭＯＳ５０がオフすることにより、直流電源４の電源電圧ＶＢに基づき負荷３に印加されていた負荷電源電圧ＶＬは遮断される。   The timer 21 of the control circuit 20 counts the elapsed time from the timing t1, and when the count value exceeds a predetermined overcurrent detection threshold, the relay MOS 50 is turned off at the timing t2. When the relay MOS 50 is turned off, the load power supply voltage VL applied to the load 3 based on the power supply voltage VB of the DC power supply 4 is cut off.

また、リレー用ＭＯＳ５０がオフすることにより、シャント抵抗４０に流れる電流が遮断されるため、シャント抵抗４０の両端に発生する電位差は、シャント抵抗４０に流れる電流の減少に伴って低下する。過電流検出回路１０に異常がなければ、シャント抵抗４０の両端の電位差が電流低下に伴って所定の閾値未満になる。これにより、過電流検出回路１０は過電流検出信号ＶＣの出力を停止する（例えば、過電流検出信号ＶＣのレベルがハイレベルからローレベルに変化）。   Further, since the relay MOS 50 is turned off, the current flowing through the shunt resistor 40 is interrupted, so that the potential difference generated at both ends of the shunt resistor 40 decreases as the current flowing through the shunt resistor 40 decreases. If there is no abnormality in the overcurrent detection circuit 10, the potential difference across the shunt resistor 40 becomes less than a predetermined threshold as the current decreases. As a result, the overcurrent detection circuit 10 stops outputting the overcurrent detection signal VC (for example, the level of the overcurrent detection signal VC changes from the high level to the low level).

制御回路２０の判定部２２は、リレー用ＭＯＳ５０がオフした時点（タイミングｔ２）から所定の一定の判定待ち時間Ａの経過時（タイミングｔ３）に過電流検出信号ＶＣをモニターする。過電流検出回路１０の異常が無ければ、過電流検出信号ＶＣの出力はタイミングｔ３で既に停止している。このため、制御回路２０の判定部２２は、過電流検出信号ＶＣの出力がタイミングｔ３で停止している場合（例えば、過電流検出信号ＶＣのレベルが過電流の検出がされていないときのローレベルに一致する場合）、負荷過電流が発生したと判定したことを表すダイアグＤＧを出力する。   The determination unit 22 of the control circuit 20 monitors the overcurrent detection signal VC when a predetermined constant determination waiting time A has elapsed (timing t3) from when the relay MOS 50 is turned off (timing t2). If there is no abnormality in the overcurrent detection circuit 10, the output of the overcurrent detection signal VC has already stopped at the timing t3. For this reason, when the output of the overcurrent detection signal VC is stopped at the timing t3 (for example, when the level of the overcurrent detection signal VC is not detected as an overcurrent), the determination unit 22 of the control circuit 20 When the level coincides), a diagnosis DG indicating that it is determined that a load overcurrent has occurred is output.

一方、例えば、過電流検出回路１０の負荷３側（リレー用ＭＯＳ５０側）の入力ノード（例えば図１の場合、コンパレータ１６の反転入力端子）と電流経路６０との接続が外れる異常が発生すると（図３の場合）、負荷３側の入力ノードに入力される電圧Ｖ３が低下する。これにより、シャント抵抗４０の両端の電位差として過電流検出回路１０に入力されて計測される電位差が大きくなるため、過電流検出回路１０は、シャント抵抗４０の両端の電位差が上昇したと（誤って）計測する。   On the other hand, for example, when an abnormality occurs in which the connection between the input path on the load 3 side (the relay MOS 50 side) of the overcurrent detection circuit 10 (for example, the inverting input terminal of the comparator 16 in FIG. 1) and the current path 60 is disconnected ( In the case of FIG. 3, the voltage V3 input to the input node on the load 3 side decreases. As a result, the potential difference input to the overcurrent detection circuit 10 and measured as the potential difference between both ends of the shunt resistor 40 becomes large. Therefore, the overcurrent detection circuit 10 assumes that the potential difference between both ends of the shunt resistor 40 has increased (incorrectly). )measure.

その結果、過電流検出回路１０は、上記同様に、シャント抵抗４０の両端の電位差が所定の過電流判定開始閾値以上とタイミングｔ１で計測されると、過電流検出信号ＶＣの出力を開始する（例えば、過電流検出信号ＶＣのレベルがローレベルからハイレベルに変化）。   As a result, as described above, the overcurrent detection circuit 10 starts outputting the overcurrent detection signal VC when the potential difference between both ends of the shunt resistor 40 is measured at a timing t1 that is equal to or greater than a predetermined overcurrent determination start threshold ( For example, the level of the overcurrent detection signal VC changes from a low level to a high level).

制御回路２０のタイマー２１は、タイミングｔ１からの経過時間をカウントし、そのカウント値が所定の過電流検出閾値を超えると、リレー用ＭＯＳ５０をタイミングｔ２でオフにする。リレー用ＭＯＳ５０がオフすることにより、直流電源４の電源電圧ＶＢに基づき負荷３に印加されていた負荷電源電圧ＶＬは遮断される。   The timer 21 of the control circuit 20 counts the elapsed time from the timing t1, and when the count value exceeds a predetermined overcurrent detection threshold, the relay MOS 50 is turned off at the timing t2. When the relay MOS 50 is turned off, the load power supply voltage VL applied to the load 3 based on the power supply voltage VB of the DC power supply 4 is cut off.

また、リレー用ＭＯＳ５０がオフすることにより、シャント抵抗４０に流れる電流が遮断されるため、シャント抵抗４０の両端に発生する電位差は、シャント抵抗４０に流れる電流の減少に伴って低下する。しかしながら、例えば、過電流検出回路１０の負荷３側の入力ノードと電流経路６０との接続が外れる異常が発生していると、シャント抵抗４０の両端の電位差は低下しても、過電流検出回路１０に入力される電位差は低下せず、所定の過電流判定開始閾値以上のままである。したがって、過電流検出回路１０は、リレー用ＭＯＳ５０がオフになっても、過電流検出信号ＶＣの出力を継続する（例えば、過電流検出信号ＶＣのレベルをハイレベルのまま維持）。   Further, since the relay MOS 50 is turned off, the current flowing through the shunt resistor 40 is interrupted, so that the potential difference generated at both ends of the shunt resistor 40 decreases as the current flowing through the shunt resistor 40 decreases. However, for example, if an abnormality occurs in which the connection between the input node on the load 3 side of the overcurrent detection circuit 10 and the current path 60 has occurred, the overcurrent detection circuit is not affected even if the potential difference between both ends of the shunt resistor 40 is reduced. The potential difference input to 10 does not decrease and remains above the predetermined overcurrent determination start threshold. Accordingly, the overcurrent detection circuit 10 continues to output the overcurrent detection signal VC even when the relay MOS 50 is turned off (for example, the level of the overcurrent detection signal VC is maintained at a high level).

制御回路２０の判定部２２は、リレー用ＭＯＳ５０がオフした時点（タイミングｔ２）から所定の一定の判定待ち時間Ａの経過時（タイミングｔ３）に過電流検出信号ＶＣをモニターする。過電流検出回路１０に異常があれば、過電流検出信号ＶＣの出力はタイミングｔ３でも継続している。このため、制御回路２０の判定部２２は、過電流検出信号ＶＣの出力がタイミングｔ３で停止せずに継続している場合（例えば、過電流検出信号ＶＣのレベルが過電流の検出がされているときのハイレベルに一致する場合）、過電流検出回路１０による電位差の計測に異常があることを表すダイアグＤＧを出力する。   The determination unit 22 of the control circuit 20 monitors the overcurrent detection signal VC when a predetermined constant determination waiting time A has elapsed (timing t3) from when the relay MOS 50 is turned off (timing t2). If there is an abnormality in the overcurrent detection circuit 10, the output of the overcurrent detection signal VC continues at timing t3. For this reason, when the output of the overcurrent detection signal VC continues without stopping at the timing t3 (for example, the level of the overcurrent detection signal VC is detected as an overcurrent), the determination unit 22 of the control circuit 20 If it is coincident with the high level at the time of detection), a diagnosis DG indicating that there is an abnormality in the measurement of the potential difference by the overcurrent detection circuit 10 is output.

このように、制御回路２０は、例えば、過電流検出回路１０の負荷３側の入力ノードと電流経路６０との接続が外れる異常が発生しても、負荷過電流の発生と誤検出することを防止できる。また、制御回路２０は、リレー用ＭＯＳ５０をオフさせた異常原因を判別できるので、その異常原因に応じた別々のダイアグＤＧを異常情報として外部装置に出力することもできる。   As described above, for example, even when an abnormality occurs in which the connection between the input node on the load 3 side of the overcurrent detection circuit 10 and the current path 60 is disconnected, the control circuit 20 erroneously detects the occurrence of the load overcurrent. Can be prevented. In addition, since the control circuit 20 can determine the cause of the abnormality that has turned off the relay MOS 50, it can also output a separate diagnosis DG corresponding to the cause of the abnormality to the external device as abnormality information.

また、制御回路２０は、異常原因毎のダイアグＤＧを表示装置やスピーカ等の報知手段により出力できる。そのため、作業者は、そのダイアグＤＧの内容に基づいて、過電流検出回路１０（又は、過電流検出回路１０を含む電流制御装置２）の異常なのか、負荷３の異常なのかを容易に確認できる。その結果、作業者は、例えば、過電流検出回路１０（又は、過電流検出回路１０を含む電流制御装置２）と負荷３のどちらを異常品として交換すればよいのか容易に判断できる。そのため、正常品を誤って交換すること等の無駄を省くことができ、修理時の費用低減が可能となる。   Further, the control circuit 20 can output a diagnosis DG for each cause of abnormality by a notification means such as a display device or a speaker. Therefore, the operator can easily confirm whether the overcurrent detection circuit 10 (or the current control device 2 including the overcurrent detection circuit 10) is abnormal or the load 3 is abnormal based on the contents of the diagnosis DG. it can. As a result, the operator can easily determine, for example, which of the overcurrent detection circuit 10 (or the current control device 2 including the overcurrent detection circuit 10) and the load 3 should be replaced as an abnormal product. For this reason, it is possible to eliminate waste such as replacing a normal product by mistake, and it is possible to reduce costs during repair.

次に、図１に示した構成例について更に詳細に説明する。   Next, the configuration example shown in FIG. 1 will be described in more detail.

負荷３に流れる負荷電流は、直流電源４の電源電圧ＶＢによって供給される。直流電源４の具体例として、二次電池、ＤＣ／ＤＣコンバータ、レギュレータなどが挙げられる。電流制御装置２は、リレー用ＭＯＳ５０と、シャント抵抗４０と、制御部３０とを有している。   The load current flowing through the load 3 is supplied by the power supply voltage VB of the DC power supply 4. Specific examples of the DC power supply 4 include a secondary battery, a DC / DC converter, and a regulator. The current control device 2 includes a relay MOS 50, a shunt resistor 40, and a control unit 30.

リレー用ＭＯＳ５０は、負荷３と直流電源４との間に直列に接続されるスイッチング素子であり、制御回路２０から供給される駆動信号であるゲート電圧ＶＧによってオンオフするものである。図１の場合、リレー用ＭＯＳ５０は、ゲートが制御回路２０に接続され、ドレインが負荷３に接続され、ソースがシャント抵抗４０の負荷３側の端部に接続されているＰチャネル型のＭＯＳＦＥＴを備えている。   The relay MOS 50 is a switching element connected in series between the load 3 and the DC power supply 4, and is turned on / off by a gate voltage VG that is a drive signal supplied from the control circuit 20. In the case of FIG. 1, the relay MOS 50 is a P-channel type MOSFET having a gate connected to the control circuit 20, a drain connected to the load 3, and a source connected to the end of the shunt resistor 40 on the load 3 side. I have.

リレー用ＭＯＳ５０は、ゲート電圧ＶＧに従って、直流電源４と負荷３とを結ぶ電流経路６０を導通／遮断可能な半導体リレーである。リレー用ＭＯＳ５０は、ゲート電圧ＶＧがローレベルのとき、電流経路６０が導通するようにオンし、ゲート電圧ＶＧがハイレベルのとき、電流経路６０が遮断するようにオフする。電流経路６０が導通状態では、シャント抵抗４０には電流が流れ、負荷３には負荷電源電圧ＶＬが印加され、電流経路６０が遮断状態では、シャント抵抗４０には電流が流れず、負荷３には負荷電源電圧ＶＬが印加されない。   The relay MOS 50 is a semiconductor relay capable of conducting / cutting off a current path 60 connecting the DC power supply 4 and the load 3 in accordance with the gate voltage VG. The relay MOS 50 is turned on so that the current path 60 becomes conductive when the gate voltage VG is at a low level, and is turned off so that the current path 60 is cut off when the gate voltage VG is at a high level. When the current path 60 is in a conductive state, a current flows through the shunt resistor 40, and the load power supply voltage VL is applied to the load 3. When the current path 60 is in a cut-off state, no current flows through the shunt resistor 40 and No load power supply voltage VL is applied.

シャント抵抗４０は、リレー用ＭＯＳ５０と直流電源４との間に直列に接続される抵抗素子であり、電流経路６０に直列に挿入された電流検出用素子である。   The shunt resistor 40 is a resistance element connected in series between the relay MOS 50 and the DC power supply 4, and is a current detection element inserted in series in the current path 60.

制御部３０は、シャント抵抗４０の両端の電位差を計測する過電流検出回路１０と、過電流検出回路１０の計測結果に従ってリレー用ＭＯＳ５０のオンオフを制御する制御回路２０とを有している。   The control unit 30 includes an overcurrent detection circuit 10 that measures a potential difference between both ends of the shunt resistor 40, and a control circuit 20 that controls on / off of the relay MOS 50 according to the measurement result of the overcurrent detection circuit 10.

過電流検出回路１０は、シャント抵抗４０と、基準電圧生成用抵抗１４と、定電流源１５と、コンパレータ１６とを有している。過電流検出回路１０の直流電源４側の入力ノード（図１の場合、例えば、基準電圧生成用抵抗１４の直流電源４側の一端）は、シャント抵抗４０と直流電源４とを結ぶ電流経路６０に接続点１１で接続される。過電流検出回路１０の負荷３側（リレー用ＭＯＳ５０側）の入力ノード（図１の場合、例えば、コンパレータ１６の反転入力端子）は、シャント抵抗４０とリレー用ＭＯＳ５０とを結ぶ電流経路６０に接続点１３で接続される。   The overcurrent detection circuit 10 includes a shunt resistor 40, a reference voltage generation resistor 14, a constant current source 15, and a comparator 16. An input node on the DC power supply 4 side of the overcurrent detection circuit 10 (in the case of FIG. 1, for example, one end of the reference voltage generating resistor 14 on the DC power supply 4 side) is a current path 60 that connects the shunt resistor 40 and the DC power supply 4. Are connected at connection point 11. The input node on the load 3 side (relay MOS 50 side) of the overcurrent detection circuit 10 (in the case of FIG. 1, for example, the inverting input terminal of the comparator 16) is connected to a current path 60 connecting the shunt resistor 40 and the relay MOS 50. Connected at point 13.

シャント抵抗４０の直流電源４側の端部は、基準電圧生成用抵抗１４の直流電源４側の一端に接続され、基準電圧生成用抵抗１４の直流電源４とは反対側の他端は、定電流源１５に接続される。基準電圧生成用抵抗１４と定電流源１５との間の中間ノード１２から出力される電圧Ｖ２は、コンパレータ１６の非反転入力端子に供給される。電圧Ｖ２は、シャント抵抗４０の直流電源４側の端部の電圧Ｖ１から、定電流源１５による定電流が基準電圧生成用抵抗１４を流れることによって生じる電圧降下分を減算した電圧である。シャント抵抗４０の負荷３側の端部の電圧Ｖ３は、コンパレータ１６の反転入力端子に入力される。過電流よりも低い電流値の正常時の電流がシャント抵抗４０に流れているときに、コンパレータ１６が過電流を誤検出しないように、そのような正常時において、電圧Ｖ３は電圧Ｖ２よりも大きくなるように設定されている。   The end of the shunt resistor 40 on the DC power supply 4 side is connected to one end of the reference voltage generating resistor 14 on the DC power supply 4 side, and the other end of the reference voltage generating resistor 14 opposite to the DC power supply 4 is fixed. Connected to the current source 15. The voltage V2 output from the intermediate node 12 between the reference voltage generating resistor 14 and the constant current source 15 is supplied to the non-inverting input terminal of the comparator 16. The voltage V2 is a voltage obtained by subtracting a voltage drop caused by a constant current from the constant current source 15 flowing through the reference voltage generating resistor 14 from the voltage V1 at the end of the shunt resistor 40 on the DC power supply 4 side. The voltage V3 at the end of the shunt resistor 40 on the load 3 side is input to the inverting input terminal of the comparator 16. The voltage V3 is larger than the voltage V2 at such a normal time so that the comparator 16 does not erroneously detect the overcurrent when a normal current having a current value lower than the overcurrent flows through the shunt resistor 40. It is set to be.

シャント抵抗４０の両端の電位差（Ｖ１−Ｖ３）は、直流電源４とシャント抵抗４０との間の電流経路６０の電圧Ｖ１から、シャント抵抗４０とリレー用ＭＯＳ５０との間の電流経路６０の電圧Ｖ３を引いた差である。電位差（Ｖ１−Ｖ３）が、過電流検出回路１０に入力される。   The potential difference (V1−V3) across the shunt resistor 40 is derived from the voltage V1 of the current path 60 between the DC power supply 4 and the shunt resistor 40 to the voltage V3 of the current path 60 between the shunt resistor 40 and the relay MOS 50. The difference minus. The potential difference (V1−V3) is input to the overcurrent detection circuit 10.

直流電源４からシャント抵抗４０に電流が流れることにより、電圧Ｖ３が低下する。過電流検出回路１０は、電圧Ｖ３の低下により電圧Ｖ３が電圧Ｖ２よりも低くなると、シャント抵抗４０の両端の電位差が所定値以上であると計測する。コンパレータ１６は、電圧Ｖ３が電圧Ｖ２よりも低いと計測される場合（つまり、シャント抵抗４０の両端の電位差が所定値以上と計測される場合）、負荷３に過電流が流れたとして、ハイレベルの過電流検出信号ＶＣを出力する（過電流検出信号ＶＣをローレベルからハイレベルに切り替える）。   When a current flows from the DC power supply 4 to the shunt resistor 40, the voltage V3 decreases. When the voltage V3 becomes lower than the voltage V2 due to the decrease in the voltage V3, the overcurrent detection circuit 10 measures that the potential difference between both ends of the shunt resistor 40 is equal to or greater than a predetermined value. When the comparator 16 measures that the voltage V3 is lower than the voltage V2 (that is, when the potential difference between both ends of the shunt resistor 40 is measured to be equal to or greater than a predetermined value), the comparator 16 assumes that an overcurrent has flowed through the load 3 and is at a high level. The overcurrent detection signal VC is output (the overcurrent detection signal VC is switched from the low level to the high level).

制御回路２０は、タイマー２１と判定部２２とを有している。制御回路２０は、例えばＣＰＵを備えるマイクロコンピュータを含んで構成された回路である。タイマー２１は、ハイレベルの過電流検出信号ＶＣの出力時点を起点に経過時間をカウントするデジタル回路である。また、タイマー２１は、リレー用ＭＯＳ５０のオフ時点を起点に経過時間をカウントするデジタル回路である。   The control circuit 20 includes a timer 21 and a determination unit 22. The control circuit 20 is a circuit configured to include a microcomputer including a CPU, for example. The timer 21 is a digital circuit that counts the elapsed time from the output point of the high level overcurrent detection signal VC. The timer 21 is a digital circuit that counts elapsed time from the time when the relay MOS 50 is turned off.

判定部２２は、図２で示したように、過電流検出信号ＶＣの出力がタイミングｔ３で停止していることを検出することで、リレー用ＭＯＳ５０をオフにした後のシャント抵抗４０の両端の電位差が所定値未満と計測される場合、負荷の異常により過電流が発生したと判定する。一方、判定部２２は、図３に示したように、過電流検出信号ＶＣの出力がタイミングｔ３で停止せずに継続していることを検出することで、リレー用ＭＯＳ５０をオフにした後のシャント抵抗４０の両端の電位差が所定値以上と計測される場合、当該電位差の計測に異常があると判定する。   As shown in FIG. 2, the determination unit 22 detects that the output of the overcurrent detection signal VC is stopped at the timing t3, so that both ends of the shunt resistor 40 after the relay MOS 50 is turned off are detected. When the potential difference is measured to be less than the predetermined value, it is determined that an overcurrent has occurred due to a load abnormality. On the other hand, as shown in FIG. 3, the determination unit 22 detects that the output of the overcurrent detection signal VC continues without stopping at the timing t <b> 3, thereby turning off the relay MOS 50. When the potential difference between both ends of the shunt resistor 40 is measured to be equal to or greater than a predetermined value, it is determined that there is an abnormality in the measurement of the potential difference.

以上、電流制御装置及び制御システムを実施形態例により説明したが、本発明は上記実施形態例に限定されるものではない。他の実施形態例の一部又は全部との組み合わせや置換などの種々の変形及び改良が、本発明の範囲内で可能である。   As described above, the current control device and the control system have been described using the embodiment. However, the present invention is not limited to the embodiment. Various modifications and improvements, such as combinations and substitutions with part or all of other example embodiments, are possible within the scope of the present invention.

例えば、本発明に係る電流制御装置として、上述の実施形態では、リレー用ＭＯＳ５０、シャント抵抗４０及び制御部３０を内蔵する電流制御装置２を例示した。しかしながら、負荷と電源との間に接続されるスイッチング素子、及びスイッチング素子と電源との間に接続されるシャント抵抗は、スイッチング素子をオフに制御する制御部とは別の筐体に配置されてもよい。   For example, as the current control device according to the present invention, the current control device 2 including the relay MOS 50, the shunt resistor 40, and the control unit 30 is illustrated in the above-described embodiment. However, the switching element connected between the load and the power source, and the shunt resistor connected between the switching element and the power source are arranged in a separate casing from the control unit that controls the switching element to be turned off. Also good.

また、負荷と電源との間に接続されるスイッチング素子として、上述の実施形態では、Ｐチャネル型のＭＯＳＦＥＴを例示した。しかしながら、当該スイッチング素子は、Ｎチャネル型のＭＯＳＦＥＴ、ＩＧＢＴ，バイポーラトランジスタ等の他のスイッチング素子でもよい。   In addition, as the switching element connected between the load and the power source, the P-channel type MOSFET is exemplified in the above-described embodiment. However, the switching element may be another switching element such as an N-channel MOSFET, IGBT, or bipolar transistor.

また、本発明に係る電流制御装置として、負荷３に流れる負荷電流を監視する電流制御装置２を例示したが、これ以外の電流制御装置でもよい。例えば、本発明に係る電流制御装置は、負荷３に電流を供給するシリーズレギュレータやスイッチングレギュレータ等の電源装置であってもよい。   Moreover, although the current control device 2 that monitors the load current flowing in the load 3 is illustrated as the current control device according to the present invention, other current control devices may be used. For example, the current control device according to the present invention may be a power supply device such as a series regulator or a switching regulator that supplies current to the load 3.

また、上述の実施形態では、シャント抵抗の両端の電位差の計測異常の原因として、過電流検出回路１０の負荷３側の入力ノードと電流経路６０との接続が外れる異常が発生したケースを例示した。しかしながら、当該計測異常の原因は、コンパレータ１６自体の故障であってもよい。判定部２２は、コンパレータ１６自体の故障により出力された過電流検出信号ＶＣに従ってリレー用ＭＯＳ５０をオフした後も、過電流検出信号ＶＣの出力が継続して計測される場合（すなわち、シャント抵抗４０の両端の電位差が所定値以上と計測される場合）、電位差の計測に異常があると判定する。   Moreover, in the above-described embodiment, a case where an abnormality occurs in which the connection between the input node on the load 3 side of the overcurrent detection circuit 10 and the current path 60 has occurred as a cause of the measurement abnormality of the potential difference between both ends of the shunt resistor is illustrated. . However, the cause of the measurement abnormality may be a failure of the comparator 16 itself. The determination unit 22 is configured to continuously measure the output of the overcurrent detection signal VC even after the relay MOS 50 is turned off in accordance with the overcurrent detection signal VC output due to the failure of the comparator 16 itself (that is, the shunt resistor 40). When the potential difference between both ends of the sensor is measured to be equal to or greater than a predetermined value), it is determined that the measurement of the potential difference is abnormal.

１ 制御システム
２ 電流制御装置
３ 負荷
４ 直流電源
１０ 過電流検出回路
１４ 基準電圧生成用抵抗
１５ 定電流源
１６ コンパレータ
２０ 制御回路
３０ 制御部
４０ シャント抵抗
５０ リレー用ＭＯＳ（スイッチング素子の一例）
６０ 電流経路 DESCRIPTION OF SYMBOLS 1 Control system 2 Current control apparatus 3 Load 4 DC power supply 10 Overcurrent detection circuit 14 Reference voltage generation resistor 15 Constant current source 16 Comparator 20 Control circuit 30 Control unit 40 Shunt resistor 50 Relay MOS (an example of a switching element)
60 Current path

Claims (6)

負荷と電源との間に接続されるスイッチング素子と、
前記スイッチング素子と前記電源との間に接続されるシャント抵抗と、
前記シャント抵抗の両端の電位差が所定値以上と計測される場合、前記スイッチング素子をオフにする制御部とを有する、電流制御装置であって、
前記制御部は、前記スイッチング素子をオフにした後の前記両端の電位差が前記所定値以上と計測される場合、前記電位差の計測に異常があると判定することを特徴とする、電流制御装置。 A switching element connected between the load and the power source;
A shunt resistor connected between the switching element and the power source;
A current control device having a control unit for turning off the switching element when a potential difference between both ends of the shunt resistor is measured to be a predetermined value or more;
The said control part determines with the measurement of the said potential difference having abnormality, when the potential difference of the said both ends after turning off the said switching element is measured more than the said predetermined value, The current control apparatus characterized by the above-mentioned. 前記制御部は、前記両端の電位差が前記所定値以上と計測されるときに出力される所定の信号が、前記スイッチング素子をオフにしても出力される場合、前記電位差の計測に異常があると判定する、請求項１に記載の電流制御装置。   When the predetermined signal output when the potential difference between the both ends is measured to be equal to or greater than the predetermined value is output even when the switching element is turned off, the control unit has an abnormality in the measurement of the potential difference. The current control device according to claim 1, wherein the current control device is determined. 前記制御部は、前記スイッチング素子をオフにしてから所定時間経過時に前記所定の信号の出力がある場合、前記電位差の計測に異常があると判定する、請求項２に記載の電流制御装置。   The current control device according to claim 2, wherein the control unit determines that there is an abnormality in the measurement of the potential difference when the predetermined signal is output when a predetermined time elapses after the switching element is turned off. 前記制御部は、前記電位差の計測異常を、前記両端の電位差を計測する計測部と、前記スイッチング素子と前記シャント抵抗とを結ぶ電流経路との接続異常と判定する、請求項１から３のいずれか一項に記載の電流制御装置。   4. The control unit according to claim 1, wherein the control unit determines the measurement abnormality of the potential difference as a connection abnormality between a measurement unit that measures the potential difference between the both ends and a current path that connects the switching element and the shunt resistor. 5. The current control device according to claim 1. 前記制御部は、前記スイッチング素子をオフにした後の前記両端の電位差が前記所定値未満と計測される場合、過電流が発生したと判定する、請求項１から４のいずれか一項に記載の電流制御装置。   5. The control unit according to claim 1, wherein the control unit determines that an overcurrent has occurred when a potential difference between the both ends after the switching element is turned off is measured to be less than the predetermined value. 6. Current control device. 負荷と、前記負荷に流れる負荷電流を監視する電流制御装置とを備え、
前記電流制御装置は、
前記負荷と電源との間に接続されるスイッチング素子と、
前記スイッチング素子と前記電源との間に接続されるシャント抵抗と、
前記シャント抵抗の両端の電位差が所定値以上と計測された場合、前記スイッチング素子をオフにする制御部とを有し、
前記制御部は、前記スイッチング素子をオフにした後の前記両端の電位差が前記所定値以上と計測される場合、前記電位差の計測に異常があると判定し、前記スイッチング素子をオフにした後の前記両端の電位差が前記所定値未満と計測される場合、前記負荷に異常があると判定する、制御システム。 A load, and a current control device that monitors a load current flowing through the load,
The current controller is
A switching element connected between the load and a power source;
A shunt resistor connected between the switching element and the power source;
A control unit that turns off the switching element when a potential difference between both ends of the shunt resistor is measured to be a predetermined value or more;
When the potential difference between the both ends after the switching element is turned off is measured to be equal to or greater than the predetermined value, the control unit determines that there is an abnormality in the measurement of the potential difference, and after the switching element is turned off. A control system that determines that the load is abnormal when the potential difference between the two ends is measured to be less than the predetermined value.
JP2012268657A 2012-12-07 2012-12-07 Control system Expired - Fee Related JP5998895B2 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001333528A (en) * 2000-05-19 2001-11-30 Denso Corp Protection apparatus against overcurrent
JP2007252134A (en) * 2006-03-17 2007-09-27 Toyota Motor Corp Load driver and automobile mounting it

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001333528A (en) * 2000-05-19 2001-11-30 Denso Corp Protection apparatus against overcurrent
JP2007252134A (en) * 2006-03-17 2007-09-27 Toyota Motor Corp Load driver and automobile mounting it

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