Terminal protection voltage detection circuit and power supply device

Abstract

To provide a voltage detection circuit for protecting terminals, which detects current of each output terminal and with which burnout risk can be eliminated.SOLUTION: In order to protect a terminal base having a plurality of output terminals of a power source device, a voltage detection circuit for protecting the terminals, includes a current detection unit that detects a plurality of output currents respectively flowing to a plurality of loads from the power source device via a plurality of output terminals, a first comparator that compares the sum of the detected output currents with a prescribed first threshold, and outputs a first comparison result signal when the sum of the detected output currents is equal to or greater than the first prescribed threshold, a second comparator that compares the maximum value among the detected output currents with a prescribed second threshold, and outputs a second comparison result signal when the maximum value is equal to or greater than the second threshold, and a current stop unit that stops a current flow from the power source device to the plurality of output terminals on the basis of the first comparison result signal or the second comparison result signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a terminal protection voltage detection circuit for protecting a plurality of terminals of a power supply device, and to a power supply device including the terminal protection voltage detection circuit. [Background technology]

[0002] A power supply device according to the prior art is provided with a terminal block having multiple output terminals for connecting multiple loads (see, for example, Patent Document 1). Generally, for a power supply device that can output a large current, for example, the terminal block having multiple output terminals must be large in size according to the output current. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-116366 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the actual terminal block in the power supply is made larger, the wiring becomes thicker and more difficult to process. Also, even if the wiring is divided for each load to divide the output current, if the load is shorted and destroyed, the output current will concentrate at that point, and the wiring of the corresponding output terminal may burn out.

[0005] Furthermore, if a user intends to connect two wires in parallel, but one wire becomes disconnected due to a misconnection, and output current is concentrated in one of the wires, that wire may burn out.

[0006] The object of the present invention is to solve the above problems and to provide a terminal protection voltage detection circuit that can detect the current at each output terminal and eliminate the risk of burnout as described above, and a power supply device that is equipped with the terminal protection voltage detection circuit. [Means for solving the problem]

[0007] A terminal protection voltage detection circuit according to one aspect of the present invention comprises: A terminal protection voltage detection circuit for protecting a terminal block having a plurality of output terminals in a power supply device, a current detection unit that detects a plurality of output currents flowing from the power supply device to a plurality of loads via a plurality of output terminals; a first comparator that compares the sum of the detected plurality of output currents with a predetermined first threshold value, and outputs a first comparison result signal when the sum of the plurality of output currents is equal to or greater than the first threshold value; a second comparator that compares a maximum value of the detected plurality of output currents with a predetermined second threshold value, and outputs a second comparison result signal when the maximum value is equal to or greater than the second threshold value; a current stopping unit that stops current from flowing from the power supply device to the plurality of output terminals based on the first comparison result signal or the second comparison result signal; Equipped with. [Effects of the Invention]

[0008] Therefore, the terminal protection voltage detection circuit according to the present invention can detect the current at each output terminal and eliminate the risk of burnout as described above. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing an example of the configuration of a power supply device including a terminal protection voltage detection circuit 20 according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings, in which the same or similar components are designated by the same reference numerals.

[0011] (Inventor's Knowledge) As described above, in conventional power supply devices equipped with a terminal block having multiple output terminals for connecting multiple loads, for example, in the case of a power supply device capable of outputting a large current, the terminal block having the multiple output terminals must be made larger in size in accordance with the output current. However, if the actual terminal block in the power supply device is made larger, the wiring becomes thicker, making processing difficult. Furthermore, even if separate wiring is used for each load to divide the output current, if a load shorts out and breaks down, the output current will concentrate there, which may burn the wiring of the corresponding output terminal, and this must be prevented.

[0012] Therefore, the inventors have devised a configuration in which overcurrent monitoring is performed at each output terminal to prevent each output terminal from exceeding its rated current. Specifically, after amplifying the output current of each output terminal with each differential amplifier, current control for protecting each terminal and current control for the total current are simultaneously performed, thereby enabling current control at each output terminal to be performed without significantly affecting the mounting area.

[0013] (Embodiment) FIG. 1 is a block diagram showing an example of the configuration of a power supply device including a terminal protection voltage detection circuit 20 according to an embodiment.

[0014] 1, the power supply device according to this embodiment includes a DC power supply 1, a smoothing electrolytic capacitor C1, an inverter circuit 2, a rectifier circuit 3, a smoothing electrolytic capacitor C2, a resistor Rd, a PWM control circuit 10, a terminal block 4 having four output terminals 41-44, a terminal block 5 having four output terminals 51-54, current detection resistors R1-R4, and a terminal protection voltage detection circuit 20. The inverter circuit 2 includes a MOS transistor Q1 and an inductor L1, and the rectifier circuit 3 includes two diodes D1 and D2, forming a single-phase full-wave rectifier circuit. Here, the inductors L1 and L2 form a transformer TR1 that is electromagnetically coupled with a coupling factor k.

[0015] The PWM control circuit 10 is a drive control circuit for the inverter circuit 2, and generates a PWM gate signal (drive control signal) having a predetermined period based on a feedback control signal FB from the terminal protection voltage detection circuit 20. The PWM control circuit 10 applies the PWM gate signal (drive control signal) having a predetermined period to the gate of the MOS transistor Q1 via a resistor Rd. This causes the inverter circuit 2 to switch the DC voltage from the DC power supply 1, thereby generating an AC voltage and outputting it to the rectifier circuit 3. The PWM control circuit 10 generates a PWM gate signal based on a low-level feedback control signal FB and stops generating the PWM gate signal based on a high-level feedback control signal FB. The rectifier circuit 3 converts the input AC voltage into a DC voltage and outputs it to loads 61 to 64 via current detection resistors R1 to R4 (negative side only) and the output terminals (41, 51; 42, 52; 43, 53; 44, 54) of the terminal blocks 4 and 5.

[0016] The terminal protection voltage detection circuit 20 is (1) a differential amplifier 21 having a feedback resistor R21, an output resistor R11, and an output diode D11; (2) a differential amplifier 22 having a feedback resistor R22, an output resistor R12, and an output diode D12; (3) a differential amplifier 23 having a feedback resistor R23, an output resistor R13, and an output diode D13; (4) a differential amplifier 24 having a feedback resistor R24, an output resistor R14, and an output diode D14; (5) Resistor R15, (6) Voltage dividing resistors R31 and R32, (7) Variable resistors VR1 and VR2, (8) Output resistor R33, (9) Comparators 31 and 32; (10) Output diodes D21 and D22, (11) a bipolar transistor Q11; (12) a photocoupler 25 having a light-emitting diode D31 and a phototransistor Q31; The device is configured to include:

[0017] The differential amplifiers 21 to 24 are so-called operational amplifiers, which amplify and output the difference voltage obtained by subtracting the voltage applied to the inverting input terminal from the voltage applied to the non-inverting input terminal.

[0018] The voltage across current detection resistor R11 (which is proportional to the output current I1 flowing through output terminal 51 or load 61) is applied to the inverting input terminal of differential amplifier 21, and a feedback resistor R21 is connected between the inverting input terminal and the output terminal. The output voltage V1 of differential amplifier 21 is output to the non-inverting input terminal of comparator 31 via resistor R11 and connection point P1, and is also output to the non-inverting input terminal of comparator 32 via output diode D11 and connection point P2.

[0019] The voltage across current detection resistor R12 (which is proportional to the output current I2 flowing through output terminal 52 or load 62) is applied to the non-inverting input terminal of differential amplifier 22, and a feedback resistor R22 is connected between the inverting input terminal and the output terminal. The output voltage V2 of differential amplifier 22 is output to the non-inverting input terminal of comparator 31 via resistor R12 and connection point P1, and is also output to the non-inverting input terminal of comparator 32 via output diode D12 and connection point P2.

[0020] The voltage across current detection resistor R13 (this voltage is proportional to the output current I3 flowing through output terminal 53 or load 63) is applied to the non-inverting input terminal of differential amplifier 23, and a feedback resistor R23 is connected between the inverting input terminal and the output terminal. The output voltage V3 of differential amplifier 23 is output to the non-inverting input terminal of comparator 31 via resistor R13 and connection point P1, and is also output to the non-inverting input terminal of comparator 32 via output diode D13 and connection point P2.

[0021] The voltage across the current detection resistor R14 (which is proportional to the output current I4 flowing through the output terminal 54 or the load 64) is applied to the non-inverting input terminal of the differential amplifier 24, and a feedback resistor R24 ​​is connected between the inverting input terminal and the output terminal. V4is output to the non-inverting input terminal of the comparator 31 via the resistor R14 and the connection point P1, and is also output to the non-inverting input terminal of the comparator 32 via the output diode D14 and the connection point P2.

[0022] Here, connection point P1 is connected to the negative power supply voltage -VCC via resistor R15. The positive power supply voltage +VCC is grounded via voltage-dividing resistor R31 and variable resistor VR1, and also via voltage-dividing resistor R32 and variable resistor VR2. The positive power supply voltage +VCC is connected to the anode of light-emitting diode D31 of photocoupler 25 via resistor R33, and its cathode is grounded via the collector and emitter of bipolar transistor Q11.

[0023] A voltage V11th at a connection point P11 between the voltage-dividing resistor R31 and the variable resistor VR1 is set by adjusting the variable resistor VR1 so as to correspond to the rated current of the entire current of the output terminals 51 to 54, for example, and this voltage is applied as a first threshold voltage V11 to the inverting input terminal of the comparator 31. Furthermore, a voltage V12th at a connection point P12 between the voltage-dividing resistor R32 and the variable resistor VR2 is set by adjusting the variable resistor VR2 so as to correspond to the rated current of each of the currents of the output terminals 51 to 54, for example, and this voltage is applied as a second threshold voltage V12 to the inverting input terminal of the comparator 32.

[0024] Here, the voltage V11 at the connection point P1 corresponds to be proportional to the sum (total current) of the currents flowing through the output terminals 51 to 54. Furthermore, the voltage V12 at the connection point P2 corresponds to be proportional to the maximum value of the currents flowing through the output terminals 51 to 54.

[0025] When V11 ≥ V11th, the comparator 31 applies a high-level comparison result signal SC1 to the base of the bipolar transistor Q11 via the diode D21. When V11 < V11th, the comparator 31 applies a low-level comparison result signal SC1 to the base of the bipolar transistor Q11 via the diode D21. Also, when V12 ≥ V12th, the comparator 32 applies a high-level comparison result signal SC2 to the base of the bipolar transistor Q11 via the diode D22. When V12 < V12th, the comparator 32 applies a low-level comparison result signal SC2 to the base of the bipolar transistor Q11 via the diode D22.

[0026] Here, the current detection resistors R1 to R4 (which may further include differential amplifiers 21 to 24) are an example of a current detection unit, and the comparators 31 and 32 are an example of comparators.

[0027] When either one of the comparison result signals SC1 and SC2 is at a high level, the bipolar transistor Q11 is turned on. As a result, the light-emitting diode D31 emits light, and the emitted light is incident on the phototransistor Q31, and a high-level feedback control signal FB is output to the PWM control circuit 10. On the other hand, when both of the comparison result signals SC1 and SC2 are at a low level, the bipolar transistor Q11 is turned off. As a result, the light-emitting diode D31 is turned off, and a low-level feedback control signal FB is output from the photocoupler 25 to the PWM control circuit 10.

[0028] The operation of the power supply device including the terminal protection voltage detection circuit 20 configured as described above will be described below.

[0029] Output currents I1 to I4 of the power supply device flow from output terminals 41 to 44 on the positive terminal block 4 through loads 61 to 64, respectively, and return to output terminals 51 to 54 on the negative terminal block 5. Here, current I1 flowing into output terminal 51 flows into resistor R1, and the voltage across resistor R1 is amplified by differential amplifier 21 and becomes voltage V1. Current I2 flowing into output terminal 52 flows into resistor R2, and the voltage across resistor R2 is amplified by differential amplifier 22 and becomes voltage V2. Furthermore, current I3 flowing into output terminal 53 flows into resistor R3, and the voltage across resistor R3 is amplified by differential amplifier 23 and becomes voltage V3. Furthermore, current I4 flowing into output terminal 54 flows into resistor R4, and the voltage across resistor R4 is amplified by differential amplifier 24 and becomes voltage V4.

[0030] Here, since the output terminals 41 to 44, 51, 54 of the terminal blocks 4, 5 generally have the same shape, they are set as in the following equation, for example.

[0031] R1=R2=R3=R4 R11=R12=R13=R14

[0032] (Case 1) When a current equal to or greater than the rated current (corresponding to the second threshold voltage V12th) flows through any of the output terminals 41 to 44 (when the maximum value of each current flowing through the output terminals 41 to 44 becomes equal to or greater than the rated current), (1) V1≧V12th, or (2) V2 ≥ V12th, or (3) V3≧V12th, or (4) V4≧V12th At this time, the photodiode D31 of the photocoupler 25 is turned on to generate a high-level feedback control signal FB, causing the PWM control circuit 10 to stop generating the PWM gate signal.

[0033] (Case 2) When the output current of the entire power supply exceeds its rated current (corresponding to the first threshold voltage V11th), (1) The current flowing through the output resistor R11 is V1 / R11, (2) The current flowing through the output resistor R12 is V1 / R12, (3) The current flowing through the output resistor R13 is V1 / R13, (4) The current flowing through the output resistor R14 is V1 / R14, Because the combined current is greater than the current value of -VCC / R15 flowing from the negative power supply voltage -VCC, the comparison result signal SC1 goes high. At this time, the photodiode D31 of the photocoupler 25 lights up, generating a high-level feedback control signal FB and stopping the generation of the PWM gate signal by the PWM control circuit 10.

[0034] In the above cases 1 or 2, when the current of the entire power supply device exceeds the rated current amount (first threshold current), or when the current of any of the output terminals exceeds the rated current (second threshold current), a high-level feedback control signal FB is generated to stop the generation of PWM gate signals by the PWM control circuit 10. This prevents the output terminals 41-44, 51-54 of the terminal blocks 4, 5 or their wiring from being burned and destroyed, and prevents overcurrent from flowing in the power supply device.

[0035] As described above, according to this embodiment, when wiring is performed from multiple output terminals to allow a large current to flow, it is possible to prevent load damage and current concentration at the output terminals when the terminals are not in contact, and to eliminate the risk of the output terminals or wiring burning out.

[0036] (Variation) In the above embodiment, the PWM control circuit 10 generates a PWM gate signal based on the feedback control signal FB to drive and control the inverter circuit 2, but the present invention is not limited to this, and the inverter circuit 2 may be driven and controlled by a drive control circuit such as an FM control circuit using another method, such as a method of controlling by frequency using an FM gate signal.

[0037] In the above embodiment, the terminal blocks 4 and 5 each having four output terminals 41 to 44 and 51 to 54 are provided, but the present invention is not limited to this, and a plurality of terminal blocks may be used.

[0038] In the above embodiment, the current detection resistors R1 to R4 are inserted on the negative side of the output terminals, but the present invention is not limited to this, and they may be inserted on the positive side of the output terminals.

[0039] In the above embodiment, the inverter circuit 2 is configured as a circuit that converts DC voltage into AC voltage, but the present invention is not limited to this, and the inverter circuit 2 may be configured as a circuit that converts DC power into AC power.

[0040] In the above embodiment, the rectifier circuit 3 is configured as a circuit that converts AC voltage into DC voltage, but the present invention is not limited to this, and the rectifier circuit 3 may be configured as a circuit that converts AC power into DC power.

[0041] In the above embodiment, the inverter circuit 2 is configured using a MOS transistor Q1 as a switching element, but the present invention is not limited to this, and may be configured using a switching element such as a thyristor, for example. [Industrial Applicability]

[0042] As described above in detail, the terminal protection voltage detection circuit according to the present invention can detect the current at each output terminal and eliminate the risk of burnout as described above. [Explanation of symbols]

[0043] 1 DC power supply 2. Inverter circuit 3 Rectifier circuit 4,5 Terminal block 10 PWM control circuit 20 Terminal protection voltage detection circuit 21-24 Differential amplifier 25 Photocoupler 31~32 Comparator 41~44, 51~54 Output terminals 61~64 Load C1~C2 electrolytic capacitors D1~D22 Diodes D31 Light-emitting diode L1~L2 inductors P1~P12 connection points Q1 MOS transistor Q11 Bipolar transistor Q31 Phototransistor Rd,R11~R33 Resistance R1~R4 Current detection resistors TR1 transformer VR1~VR2 variable resistors

Claims

1. A terminal protection voltage detection circuit for protecting a terminal block having a plurality of output terminals in a power supply device, a current detection unit that detects a plurality of output currents flowing from the power supply device to a plurality of loads via a plurality of output terminals; a first comparator that compares the sum of the detected plurality of output currents with a predetermined first threshold value, and outputs a first comparison result signal when the sum of the plurality of output currents is equal to or greater than the first threshold value; a second comparator that compares a maximum value of the detected plurality of output currents with a predetermined second threshold value, and outputs a second comparison result signal when the maximum value is equal to or greater than the second threshold value; a current stopping unit that stops current from flowing from the power supply device to the plurality of output terminals based on the first comparison result signal or the second comparison result signal; A voltage detection circuit for terminal protection comprising:

2. A terminal protection voltage detection circuit for protecting a terminal block having a plurality of output terminals in a power supply device, comprising: a current detection unit that detects a plurality of output currents flowing from the power supply device to a plurality of loads via a plurality of output terminals, and converts the detected plurality of output currents into a plurality of voltage values; a third comparator that compares the sum of the converted voltage values ​​with a predetermined third threshold value, and outputs a third comparison result signal when the sum of the converted voltage values ​​is equal to or greater than the third threshold value; a fourth comparator that compares a maximum value of the converted voltage values ​​with a predetermined fourth threshold value, and outputs a fourth comparison result signal when the maximum value is equal to or greater than the fourth threshold value; a current stopping unit that stops current from flowing from the power supply device to the plurality of output terminals based on the third comparison result signal or the fourth comparison result signal; A voltage detection circuit for terminal protection comprising:

3. the current detection unit converts the detected output currents into a plurality of voltage values, and then amplifies the voltage values.

3. The terminal protection voltage detection circuit according to claim 2.

4. the first threshold value is a rated current value of the entire terminal block, the second threshold value is a rated current value of each of the plurality of output terminals; 2. The terminal protection voltage detection circuit according to claim 1.

5. A power supply device comprising the terminal protection voltage detection circuit according to any one of claims 1 to 4, The power supply device an inverter circuit that converts DC power into AC power; a rectifier circuit that converts AC power from the inverter circuit into DC power, the current stopping unit stops the operation of the inverter circuit. power supply.

6. The inverter circuit a switching element that switches the DC power to convert it into AC power; a drive control circuit that generates a drive control signal and outputs it to the switching element; the current stopping unit stops generation of the drive control signal in the drive control circuit; 6. The power supply device according to claim 5.

7. The drive control signal is a PWM gate signal or an FM gate signal.

7. The power supply device according to claim 6.

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