JP2019004622A - Electronic device - Google Patents

Abstract

To provide an electronic device capable of suppressing generation of an inrush current.SOLUTION: An electronic device includes a booster circuit with a boosting capacitor inserted between an output terminal and a reference potential; a main relay switch for controlling supply of electric power to an input terminal of the booster circuit; a filter capacitor inserted between a midpoint between the input terminal of the booster circuit and the main relay switch and a reference potential and further includes a separation switch for separating electrical connection of the filter capacitor with the booster circuit between the midpoint connected with the filter capacitor and the input terminal of the booster circuit.SELECTED DRAWING: Figure 1

Description

  The disclosure of this specification relates to an electronic device including a booster circuit having a capacitor.

  In order to apply a voltage higher than a power supply voltage to a load, there is an electronic device including a booster circuit. For example, Patent Document 1 discloses a booster circuit that realizes boosting of an input voltage with an inductor and a capacitor.

  In an electronic device including such a booster circuit, a booster capacitor and a decoupling capacitor (filter capacitor) constituting the booster circuit may be connected in parallel between the power supply line and the ground. The filter capacitor is inserted between the power supply line and the ground level in order to suppress voltage fluctuation of the DC power supply and reduce noise.

JP 2006-200036 A

  For example, when an electronic device including a booster circuit including a booster capacitor is adopted in a vehicle, a main capacitor that controls input of a voltage to the booster circuit is turned on, and immediately after power supply is started, a filter capacitor and Inrush current may flow through the boost capacitor. Depending on the capacitances of the filter capacitor and the boost capacitor, this inrush current may exceed the rating of the main relay.

  Accordingly, in view of the above problems, an object of the present disclosure is to provide an electronic device that can suppress inrush current.

  The invention disclosed herein employs the following technical means to achieve the above object. Note that the reference numerals in parentheses described in the claims and in this section indicate a corresponding relationship with specific means described in the embodiments described later as one aspect, and limit the technical scope of the invention. Not what you want.

  In order to achieve the above object, an electronic device disclosed in this specification includes a booster circuit (10) in which a booster capacitor (11) is inserted between an output terminal (P) and a reference potential, A main relay switch (20) for controlling the supply of power to the input terminal (Q), and a filter capacitor (30) inserted between an intermediate point between the input terminal of the booster circuit and the main relay switch and a reference potential; Is provided with a separation switch (40) for separating the electrical connection between the filter capacitor and the booster circuit between the intermediate point to which the filter capacitor is connected and the input terminal of the booster circuit.

  According to this, since the filter capacitor and the boost circuit can be electrically separated, for example, when the main relay switch is turned on, the filter capacitor and the boost capacitor are electrically disconnected by the separation switch, It is possible to realize a configuration that can suppress the inflow of the inrush current to the boost capacitor.

It is a circuit diagram which shows the structure of the electronic device which concerns on 1st Embodiment. It is a flowchart which shows the control flow of an electronic device. It is a timing chart which shows the control of an electronic device, and the change of each current and voltage accompanying it. It is a flowchart which shows the control flow of the electronic device which concerns on 2nd Embodiment. It is a timing chart which shows the control of an electronic device, and the change of each current and voltage accompanying it.

  Hereinafter, a plurality of modes for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to the matters described in the preceding embodiment may be denoted by the same reference numerals, and redundant description may be omitted. When only a part of the configuration is described in each mode, the other modes described above can be applied to the other parts of the configuration. Not only combinations of parts that clearly indicate that combinations are possible in each form, but also forms may be partially combined even if they are not clearly specified, as long as there is no problem with the combination. Is possible.

(First embodiment)
Initially, with reference to FIG. 1, schematic structure of the electronic device which concerns on this embodiment is demonstrated. In the following description, when the switch is turned on, it means that both ends are energized, and when the switch is turned off, both ends are electrically disconnected.

  The electronic device in the present embodiment is mounted on a vehicle, for example, and constitutes a part of a power supply circuit for generating a voltage related to the control of the injector.

  As shown in FIG. 1, the electronic device 100 is a device that receives a battery voltage VB that is input when an ignition switch 200 is turned on and boosts the output voltage Vout. In FIG. 1, the battery voltage VB and the electronic device 100 are illustrated as being directly connected via the ignition switch 200, but as an input voltage to the electronic device 100 when the ignition switch 200 is turned on. It is sufficient if the battery voltage VB is supplied.

  The electronic device 100 includes a booster circuit 10, a main relay switch 20, a filter capacitor 30, a separation switch 40, and a control unit 50.

  The step-up circuit 10 includes a step-up capacitor 11, an inductor 12, a step-up switching element 13, and a diode 14, and also includes a diode 15 when a separation switch 40 described later is installed.

  For example, the booster capacitor 11 has a negative electrode side connected to GND, which is a reference potential, and a positive electrode side set to the same potential as the output terminal P. The inductor 12 is connected to the positive terminal of the boost capacitor 11 via the diode 14. The diode 14 is forward from the inductor 12 toward the boost capacitor 11. That is, the inductor 12, the diode 14, and the boost capacitor 11 are connected in series between the input terminal Q of the boost circuit 10 and the reference potential GND in this order. The intermediate point between them is the output terminal P of the booster circuit 10.

  The step-up switching element 13 is, for example, a MOS transistor. The step-up switching element 13 is connected between the midpoint between the inductor 12 and the diode 14 and GND.

  The circuit constituted by the boost capacitor 11, the inductor 12, the boost switching element 13 and the diode 14 described above is a generally known boost circuit. The booster circuit 10 accumulates energy in the inductor 12 by turning on the boost switching element 13 and energy of the inductor 12 by turning off the boost switching element 13 with respect to the voltage input to the input terminal Q. Boosting at the output terminal P is realized by accumulating electric charge in the boosting capacitor 11 accompanying the release of.

  The diode 15 flows between the input terminal Q of the booster circuit 10 and the reference potential GND in order to flow a reflux current generated by energy stored in the inductor when a separation switch 40 described later is turned off. It is connected. The diode 15 need not be included in the booster circuit 10 and may be provided separately outside the booster circuit 10.

  The main relay switch 20 is composed of two switching elements 21 and 22. The switching element 11 and the switching element 12 in this embodiment are both MOS transistors. The main relay switch 20 is inserted between the ignition switch 200 and the booster circuit 10, and current is supplied from the battery when the two switching elements 21 and 22 are simultaneously turned on while the ignition switch 200 is turned on. It has become so. In the MOS transistor, a parasitic diode is formed between the drain and the source. The two switching elements 21 and 22 in this embodiment are both N-channel MOS transistors, and are arranged so that the forward directions of the parasitic diodes face each other by connecting the drain terminals to each other. Thereby, an unintended large current does not flow with respect to the reverse connection of the unintended battery. A Zener diode 23 connected to the ignition switch 200 side with respect to the main relay switch 20 is also installed for the same purpose.

  The filter capacitor 30 is a so-called decoupling capacitor, and is inserted between the intermediate point between the input terminal Q of the booster circuit 10 and the main relay switch 20 and the reference potential GND. That is, the filter capacitor 30 is connected between the power supply line for applying the battery voltage VB to the booster circuit 10 and the reference potential. The filter capacitor 30 is in a state where charges based on the potential of the power supply line can be accumulated, and voltage fluctuation at the input terminal Q of the booster circuit 10 even when voltage fluctuation of the battery voltage VB (DC power supply) occurs. This is effective in reducing noise and is also effective in reducing noise. Note that the capacitance of the filter capacitor 30 is smaller than the capacitance of the boost capacitor 11.

  The separation switch 40 is a MOS transistor, and is interposed between the booster circuit 10 and the main relay switch 20. The filter capacitor 30 is inserted between the intermediate point of the main relay switch 20 and the separation switch 40 and GND. When the separation switch 40 is turned off, the main relay switch 20 and the booster circuit 10 can be electrically separated.

  The control unit 50 is a part that controls driving of each switching element. Specifically, the control unit 50 controls on / off of each switch to the gate terminals of the switching elements 11 and 12 constituting the main relay switch 20, the gate terminal of the step-up switching element 13, and the gate terminal of the separation switch 40. The gate voltage can be applied. Further, the control unit 50 receives the voltage Va on the positive side of the boost capacitor 11 and the voltage Vb on the positive side of the filter capacitor 30. In the present embodiment, the voltage Va is equal to the output voltage Vout, and the voltage Vb is a voltage at an intermediate point between the main relay switch 20 and the separation switch 40.

  The controller 50 controls on / off of the switches 13, 21, 22, and 40 based on the values of the voltage Va and the voltage Vb.

  Next, the operation of the electronic apparatus 100 according to the present embodiment will be described with reference to FIGS. In particular, the control of the control unit 50 will be described.

  As shown in FIG. 2, step S101 is first executed. Step S101 is a step in which the control unit 50 determines whether or not the ignition switch 200 is turned on. If the ignition switch 200 is turned on, the process proceeds to step S102. Note that when the ignition switch 200 is in the OFF state, the process does not proceed to step S102 and thereafter.

  Step S102 is a step in which the control unit 50 determines whether the output voltage Vout of the booster circuit 10, that is, the voltage Va on the positive side of the boost capacitor 11 is equal to or lower than the first threshold value Vth1. When the condition of Va ≦ Vth1 is satisfied, step S102 is YES, and the process proceeds to step S103. When Va> Vth1, the process proceeds to step S109 to shift to a normal boosting operation. Details will be described later.

  Step S <b> 103 is a step in which the control unit 50 turns off the separation switch 40. The execution timing of step S103 corresponds to time t1 shown in FIG.

  Next, step S104 is executed. Step S104 is a step in which the control unit 50 turns on the main relay switch 20. Step S104 is executed with a slight time difference immediately after the execution timing of step S103, but for convenience, it is shown to be executed at time t1 in FIG.

  When the main relay switch 20 is turned on with the separation switch 40 turned off, the battery voltage VB is not applied to the input terminal Q of the booster circuit 10, and charge is stored only in the filter capacitor 30. Supplying current from the battery to the filter capacitor 30 increases the current flowing through the main relay switch 20 and increases the positive voltage Va of the filter capacitor 30.

  Next, step S105 is executed. Step S105 is a step in which the control unit 50 determines whether or not the positive voltage Vb of the filter capacitor 30 is equal to or higher than the second threshold value Vth2. When Vb ≧ Vth2 is satisfied, a YES determination is made. The second threshold value Vth2 in the present embodiment is set to be the same as the battery voltage VB. That is, when the filter capacitor 30 is fully charged, step S105 is YES. On the other hand, in the case of NO determination, step S105 is repeated without proceeding to the previous step. That is, the current state is maintained.

  When the voltage Vb on the positive electrode side of the filter capacitor 30 becomes equal to or higher than the second threshold value Vth2, step S106 is executed. In FIG. 3, Vb ≧ Vth2 is satisfied at time t2, and the main relay switch 20 is turned off by executing step S106.

  Next, step S107 is executed. In step S107, the control unit 50 turns on the separation switch 40 to electrically connect the filter capacitor 30 and the booster circuit 10. Step S107 is executed after a predetermined filter time after the execution of step S106, and the execution timing thereof is a time corresponding to time t3 in FIG.

  When the separation switch 40 is turned on with the main relay switch 20 turned off and the charge accumulated in the filter capacitor 30, the charge moves from the filter capacitor 30 to the boost capacitor 11. For this reason, a current flows through the separation switch 40, and the accumulated charge amount of the filter capacitor decreases. That is, the voltage Vb decreases. On the other hand, the voltage Va (= Vout) on the positive side of the boost capacitor 11 increases.

  Next, step S108 is executed. Step S108 is a step in which the controller 50 determines whether or not the voltage Vb on the positive electrode side of the filter capacitor 30 has fallen below the third threshold value Vth3. When Vb <Vth3 is satisfied, a YES determination is made. Vb decreases as charge moves from the filter capacitor 30 to the boost capacitor 11, but when the value decreases to a value smaller than a predetermined value (third threshold value), the process returns to step S102. Under the condition of Vb ≧ Vth3, the current state is maintained and step S108 is repeated.

  When Vb <Vth3 is satisfied as at time t4 shown in FIG. 3, step S108 is YES, and the control unit 50 determines that the output voltage Vout (= Va) of the booster circuit 10 is equal to or greater than a predetermined fourth threshold value. A step of confirming whether or not the voltage is boosted is executed. In the present embodiment, assuming that the fourth threshold value Vth4 is set to be the same as the first threshold value Vth1, this step is the same as step S102. That is, the control flow returns to step S102. Here, if the potential of the output terminal P is high enough to keep the inrush current within the allowable current value, that is, if Va> Vth4 (= Vth1) is satisfied, the process proceeds to step S109 and the normal boosting operation is performed. Migrate to

  On the other hand, in the example shown in FIG. 3, for example, Vb <Vth3 is satisfied at time t4 and the control flow returns to step S102, but Va> Vth1 is not satisfied at time t4, so step S102 is YES, The control unit 50 executes Steps S103 to S107 again.

  The second determination in step S108 is YES at time t7. The control flow returns to step S102, but Va> Vth1 is not satisfied even at time t7, so the third step S103 to step S107 are executed. At time t7, the separation switch 40 is turned off and the main relay switch 20 is turned on, and the filter capacitor 30 is charged. Then, the main relay switch 20 is turned off at time t8 when the voltage Vb on the positive electrode side of the filter capacitor 30 reaches the second threshold value Vth2, and the separation switch 40 is turned on at time t9 after the filter time. As a result, at time t10, the voltage Va on the positive side of the boost capacitor 11 exceeds the first threshold value Vth1.

  Thereafter, step S108 is executed, and Vb <Vth3 is satisfied at time t11, and the process returns to step S102. However, after time t10, Vout (= Va)> Vth1, and step S102 is NO. That is, the control flow proceeds to step S109.

  Step S109 is a step in which the control unit 50 turns on the main relay switch 20. Further, step S110 is executed. Step S110 is a step in which the control unit 50 turns on the separation switch 40. Through step S109 and step S110, the battery voltage Vb is directly input to the input terminal Q of the booster circuit 10. Subsequently, the control unit 50 executes Step S111. Step S111 is a step in which the control unit 50 controls the on / off of the boost switching element 13 to perform the boost operation. Through step S111, the electronic device 100 can output a desired voltage value. For example, in the example shown in FIG. 3, the periodic switching on / off operation of the step-up switching element 13 starts at time t12 to perform step-up.

  Next, the operation effect by adopting the electronic device 100 according to the present embodiment will be described.

  Since the electronic device 100 includes the separation switch 40 between the booster circuit 10 and the main relay switch 20, the booster circuit 10 and the main relay switch 20 can be electrically separated. Due to this electrical separation, inrush current can be prevented from flowing into the boost capacitor 11 even when the main relay switch 20 is turned on.

  When the main relay switch 20 is turned on in the state where the separation switch 40 is turned off and the booster circuit 10 is separated, the current caused by the battery voltage VB flows through the filter capacitor 30 and the inrush current to the boost capacitor 11 can be suppressed. In particular, the boost capacitor 11 is often set to have a larger capacitance than the filter capacitor 30. In this case, the inrush current to the boost capacitor 11 is increased, so that the boost circuit 10 is separated as in this embodiment. Turning on the main relay switch 20 in this state is effective in improving the inrush current resistance of the booster circuit 10.

  Since the main relay switch 20 is turned off and the separation switch 40 is turned on when the filter capacitor 30 reaches a predetermined charge amount, the filter capacitor 30 is not directly connected to the boost capacitor 11. Thirty charges can be transferred to the boost capacitor 11. That is, the filter capacitor 30 provides a buffer for the boost capacitor 11.

  In this manner, by repeating the separation and connection by the separation switch 40, the boost capacitor 11 can be charged stepwise while preventing direct current from flowing into the boost capacitor 11 from the battery. That is, the inrush current to the boost capacitor 11 can be suppressed, and the electrical reliability of the boost circuit 10 can be improved.

  In addition, after the electronic device 100 starts the boosting operation, until the ignition switch 200 is turned off, the separation is performed even when the output voltage Vout (= Va) of the boosting circuit 10 is lower than the first threshold value Vth1. It is preferable to maintain the state in which the switch 40 is turned on. For example, when Vout falls below Vth1 due to an instantaneous interruption of the battery or noise, if the battery and the booster circuit 10 are disconnected unintentionally, the boosting operation may not be maintained and Vout may not be maintained.

(Second Embodiment)
In the above-described embodiment, the example in which the on / off trigger of the separation switch 40 and the main relay switch 20 depends on the voltage Vb on the positive electrode side of the filter capacitor 30 has been described. That is, the example in which on / off of the separation switch 40 and the main relay switch 20 is controlled based on the relationship between the voltage Vb and the threshold voltages Vth2 and Vth3 has been described.

  On the other hand, the control part 50 in this embodiment has a timer and controls on / off of the separation switch 40 and the main relay switch 20 based on time. With reference to FIG. 4 and FIG. 5, the operation of the electronic apparatus 100 in the present embodiment will be described. Hereinafter, differences from the first embodiment will be mainly described.

  As shown in FIG. 4, the control unit 50 determines whether the ignition switch 200 is on or off by executing Step S <b> 201. This step is the same as step S101 in the first embodiment.

  Next, the control unit 50 executes step S202 to determine whether the voltage on the positive side of the boost capacitor 11, that is, the output voltage Vout of the boost circuit 10 is equal to or lower than the first threshold value Vth1. This step is the same as step S102 in the first embodiment. Here, if the voltage of Vout exceeds Vth1, an excessive inrush current does not flow, so the process proceeds to step S209. Steps S209 to S211 are boost operations corresponding to steps S109 to S111 in the first embodiment. On the other hand, if Vout ≦ Vth1 is satisfied in step S202, the determination is YES, and the process proceeds to step S203.

  Step S203 and step S204 are the same as step S103 and step S104, respectively, the separation switch 40 is turned off, and the main relay switch 20 is turned on. The execution timing of step S203 and step S204 corresponds to time t1 shown in FIG. When the main relay switch 20 is turned on at time t1, charge accumulation in the filter capacitor 30 is started, and the voltage Vb increases.

  After step S204, the control unit 50 executes step S205. Step S205 is a step in which the control unit 50 determines whether or not a predetermined time T1 has elapsed since step S204 was executed. The predetermined time T1 is determined based on the time during which the filter capacitor 30 is fully charged or stored corresponding to full charge when the separation switch 40 is OFF. For example, the predetermined time T1 is based on a time constant unique to the filter capacitor 30. The predetermined time T1 corresponds to the first period described in the claims.

  At time t2 when the predetermined time T1 has elapsed from time t1, step S206 is executed, and then step S207 is executed.

  Step S206 and step S207 are the same as step S106 and step S107, respectively, the main relay switch 20 is turned off, and the separation switch 40 is turned on. The execution timing of step S203 corresponds to time t2 shown in FIG. 5, and the execution timing of step S204 corresponds to time t3 shown in FIG. When the separation switch 40 is turned on at time t3, the charge of the filter capacitor 30 is transferred to the boost capacitor 11, and the voltage Va (= Vout) increases.

  Next, the control unit 50 executes Step S208. Step S208 is a step in which the control unit 50 determines whether or not a predetermined time T2 has elapsed since step S207 was executed. The predetermined time T2 is determined based on the time during which the charge is transferred from the filter capacitor 30 to the boost capacitor 11 with the main relay switch 20 turned off. For example, the predetermined time T2 is specific to the filter capacitor 30 and the boost capacitor 11 is specific. Based on the time constant of The predetermined time T2 corresponds to a second period described in the claims.

  Each step from step S203 to step S208 is repeated until step S202 is NO. That is, until the output voltage Vout of the booster circuit 10 exceeds a predetermined fourth threshold value (the same value as the first threshold value in this embodiment), the operation of storing power in the filter capacitor 30 and transferring it to the boost capacitor 11 is repeated. In the example shown in FIG. 5, the time from time t4 to time t5 is T1, and the time from time t6 to time t7 is T2. The time from time t7 to time t8 is T1, and the time from time t9 to time t11 is T2.

  In this example, since Vout> Vth1 at time t10, step S202 is NO and the process proceeds to step S209 after time t10. Therefore, after time t11, both the main relay switch 20 and the separation switch 40 are turned on, and the control unit 50 starts a normal boosting operation at time t12.

  As described above, in the present embodiment, the storage of the filter capacitor 30 and the transfer of electric charge to the boost capacitor 11 can be performed regardless of the positive side voltage of the filter capacitor 30, compared with the first embodiment. It is possible to improve the electrical reliability of the booster circuit 10 by suppressing the inrush current to the boost capacitor 11 while reducing the processing addition of the control unit 50.

(Other embodiments)
The preferred embodiment has been described above, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist disclosed in this specification.

  In each of the embodiments described above, an example in which Vout and the first threshold value Vth1 are compared after the execution of step S108 or step S208 is shown as a condition for shifting to the boosting operation. It is not necessary to use the first threshold value Vth1 used as the execution condition of step S203, and another value of the fourth threshold value Vth4 can be adopted.

  In each of the above-described embodiments, an example in which the capacitance of the boost capacitor 11 is larger than that of the filter capacitor 30 is assumed. However, the magnitudes of the capacitances of the boost capacitor 11 and the filter capacitor 30 are not limited. Even when the electrostatic capacitance of the filter capacitor 30 is the same as or larger than that of the boost capacitor 11, the electronic device 100 includes the separation switch 40, whereby the inrush current flowing into the boost circuit 10 can be suppressed. However, when the capacitance of the boost capacitor 11 is larger than that of the filter capacitor 30, the inrush current flows greatly to the boost circuit 10 side. Therefore, the effect of suppressing the inrush current by providing the separation switch 40 is that of the boost capacitor 11. This is more effective when the capacitance is larger than that of the filter capacitor 30.

  In each of the above-described embodiments, the example in which the MOS transistors are employed as the switching elements 21 and 22, the separation switch 40, and the boost switching element 13 has been described. However, the MOS transistors are not limited as long as they have a switching function. Absent. For example, an insulated gate bipolar transistor or a bipolar transistor can be employed as these switches.

  The function of the control unit 50 of the above embodiment can be achieved by, for example, an ECU. However, the configuration that exhibits the function of the control unit 50 may be, for example, various arithmetic devices mounted on the vehicle, or various arithmetic devices provided to be communicable with the vehicle. Further, a plurality of arithmetic devices may exhibit the function of the control unit 50 in cooperation. In addition, various non-transitional tangible storage media such as a flash memory and a hard disk provided in each arithmetic device can be adopted as a storage medium for storing a program executed by the control unit 50.

DESCRIPTION OF SYMBOLS 10 ... Boost circuit, 11 ... Boost capacitor, 20 ... Main relay switch, 30 ... Filter capacitor, 40 ... Separation switch, 50 ... Control part

Claims (7)

A booster circuit (10) having a booster capacitor (11) inserted between the output terminal (P) and a reference potential;
A main relay switch (20) for controlling the supply of power to the input terminal (Q) of the booster circuit;
An electronic device comprising: a filter capacitor (30) inserted between an intermediate point between the input terminal of the booster circuit and the main relay switch and the reference potential;
An electronic apparatus comprising a separation switch (40) for separating an electrical connection between the filter capacitor and the booster circuit between the intermediate point to which the filter capacitor is connected and an input terminal of the booster circuit. A control unit (50) for controlling on / off of the main relay switch and the separation switch;
When the ignition switch (200) is turned on, the control unit
2. The electronic device according to claim 1, wherein the separation switch is turned off and the main relay switch is turned on on condition that an output voltage of the booster circuit is equal to or lower than a predetermined first threshold value (Vth1). The controller is
On the condition that the voltage on the power supply line side in the filter capacitor is equal to or higher than a predetermined second threshold (Vth2), the main relay switch is turned off, and the separation switch is turned on,
3. The electronic device according to claim 2, wherein the separation switch is turned off and the main relay switch is turned on on condition that the voltage on the power supply line side of the filter capacitor is lower than a predetermined third threshold (Vth3). The controller is
Maintaining the main relay switch in an off state for a first period (T1) having a predetermined time interval, and maintaining the separation switch in an on state;
3. The electron according to claim 2, wherein after the first period, the separation switch is maintained in an off state and the main relay switch is maintained in an on state for a second period (T2) having a predetermined time interval. apparatus.   The controller turns on the separation switch and turns on the main relay switch on the condition that the output voltage of the booster circuit is higher than a predetermined fourth threshold value (Vth4), and boosts the voltage via the booster circuit. The electronic device according to claim 2, wherein the electronic device operates.   The control unit maintains the separation switch in an on state and maintains the main relay switch in an on state until the ignition switch is turned off after the boosting operation is started. 5. The electronic device according to 5.   The electronic device according to claim 1, wherein the boost capacitor has a larger capacitance than the filter capacitor.

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