JP2014099995A - Switching power supply device and power supply system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switching power supply device capable of easily controlling an output current and built in a simple configuration, and a power supply system using the same.SOLUTION: A drive pulse output unit 30 of a control unit 24 generates a drive pulse Vg for a main switching element 26 so that a difference between an own voltage signal Va derived by detecting an output voltage Vo and a target voltage value Vr becomes smaller. A target voltage value setting unit 32 outputs voltage control information Sv for regulating the target voltage value Vr, and also outputs current control information Si corresponding to an own current signal Ia derived by detecting an output current Io. A current control voltage output unit 34 generates a current control voltage Vbo corresponding to the current control information Si, and outputs the generated voltage toward a CB line 36. When a detected current control terminal voltage Vbm does not match the current control voltage Vbo to be generated on the basis of the current control information Si, the target voltage value setting unit 32 outputs voltage control information Sv for correcting the target voltage value Vr according to a voltage difference ΔVb.

Description

  The present invention relates to a switching power supply device capable of parallel operation and a power supply system using the same.

  A switching power supply device such as a switching regulator or a DC-DC converter generally includes a power conversion unit that converts an input voltage into a DC output voltage by a switching operation of the main switching element, and an on time and an off time of the main switching element. And a control unit for controlling on / off of the main switching element using the drive pulse.

  When building a power supply system that operates multiple switching power supplies in parallel and supplies power to a common load, the output current of each switching power supply is automatically balanced so that the load is not concentrated on a specific switching power supply. A switching power supply device having a function to be used is used. There are various methods for balance control of the output current, but the on-time and off-time of each main switching element are reduced so that the control units of each switching power supply device communicate with each other and the difference between the output currents becomes small. In many cases, a regulated method is used.

  Conventionally, as disclosed in, for example, Patent Document 1, since the control circuits of a plurality of switching power supply devices communicate with each other, current balance terminals (CB terminals) for external connection are connected to each other by current balance lines. There is a parallel operation power supply system. The control circuit of each switching power supply device converts its own output current into analog voltage information, exchanges the analog voltage information through the current balance line, and turns on and off the main switching element so that the output currents of each other step up and become equal Control.

  In this parallel operation power supply system, if a plurality of switching power supply devices having the same configuration are prepared and the above wiring is performed, the balance of output current can be automatically controlled without providing a special control device outside. it can. Also, so-called N + 1 redundant operation is possible, and when one unit fails, only the remaining normal switching power supply device can continue to supply the output power necessary for the load.

JP 2007-143292 A

  In the case of the switching power supply device and the parallel operation power supply system disclosed in Patent Document 1, since the balance control of the output current of the switching power supply device is performed by analog control, the configuration of the circuit for balance control becomes complicated and the number of parts increases. Further, in the circuit for balance control described in FIG. 2 of Patent Document 1, a minute voltage is amplified by using two operational amplifiers and a plurality of resistors. Offset operational amplifiers and high-precision resistors must be used, resulting in high component costs. Furthermore, in order to prevent the output current balance control from interfering with the output voltage stabilization control and oscillating, it is important to adjust the gain and phase characteristics of the output current balance control. In the configuration of the balance control circuit, there are various restrictions, so that the gain and phase characteristics cannot be freely adjusted.

  The present invention has been made in view of the above-described background art, and an object thereof is to provide a switching power supply apparatus having a simple configuration and a power supply system using the same, which can easily control an output current. To do.

  The invention according to claim 1 is a power converter that converts a DC or AC input voltage supplied to an input terminal by a switching operation of a main switching element and supplies an output voltage and an output current to a load connected to the output terminal. And a control unit that generates a drive pulse that defines an on time and an off time of the main switching element, and controls on / off of the main switching element using the drive pulse, A voltage detection circuit for detecting the output voltage or a voltage corresponding thereto and outputting a self-voltage signal; and a current detection circuit for detecting the output current or a current corresponding thereto and outputting a self-current signal; The control unit generates the drive pulse so that a difference between the self-voltage signal and a predetermined voltage target value is small, and supplies the drive signal to the main switching element. A drive pulse output unit that outputs the voltage, voltage control information that defines the voltage target value of the drive pulse output unit, and a voltage target value setting unit that outputs current control information corresponding to the self-current signal; A current control voltage output unit that generates and outputs a direct current control voltage corresponding to the current control information, and a current control terminal that enables the output of the current control voltage output unit to be connected to the outside, and The voltage target value setting unit detects the voltage of the current control terminal, and corrects the voltage target value according to the voltage difference when the voltage does not match the current control voltage to be generated based on the current control information. The voltage control information to be generated, and the main switching element is turned on / off based on the corrected voltage target value to thereby generate the voltage to be generated based on the current control information. Control voltage approaches the current control terminal voltage, the voltage difference is small switching power supply device below a certain level.

  The invention according to claim 2 is the switching power supply device according to claim 1, wherein the current control voltage output unit outputs a pulse voltage that repeats a high level and a low level at a constant period; and And a smoothing circuit that is a low-pass filter that smoothes a pulse voltage and converts it into the DC current control voltage, and the pulse generation circuit is configured to detect a high level and a low level of the pulse voltage based on the current control information. This is a switching power supply device that determines a duty ratio.

  The invention according to claim 3 is the switching power supply device according to claim 1, wherein the current control voltage output unit outputs a pulse voltage that repeats a high level and a low level at a constant period; and A smoothing circuit that is a low-pass filter that smoothes a pulse voltage and converts it to the DC current control voltage, and an amplifier circuit that has an input terminal connected to the output of the smoothing circuit and an output terminal connected to the current control terminal. The pulse generator circuit is a switching power supply device that determines a time ratio between a high level and a low level of the pulse voltage based on the current control information.

  The invention according to claim 4 is the switching power supply device according to claim 3, wherein the amplifier circuit is an emitter follower circuit.

  The invention according to claim 5 is the switching power supply device according to claim 1, wherein the current control voltage output unit outputs the DC current control voltage corresponding to the current control information, which is a digital signal, to a predetermined output. It is a switching power supply device which is a digital-analog converter that outputs via an impedance.

  The invention according to claim 6 is the switching power supply device according to claim 1, wherein the current control voltage output unit outputs the DC current control voltage corresponding to the current control information which is a digital signal. The switching power supply device includes an analog converter and an amplifier circuit having an input terminal connected to the output of the digital-analog converter and an output terminal connected to the current control terminal.

  The invention according to claim 7 is the switching power supply device according to claim 6, wherein the amplifier circuit is an emitter follower circuit.

  The invention according to claim 8 is the switching power supply device according to any one of claims 1 to 7, wherein the voltage target value setting unit is provided in the digital processor and rewrites a program recorded in the digital processor. Thus, the switching power supply device can change the voltage target value and the correction amount when correcting the voltage target value.

  A ninth aspect of the present invention is a power supply system using a plurality of the switching power supply units according to any one of the first to seventh aspects, wherein the plurality of switching power supply units have the output terminals connected in parallel to each other. The current control terminals are connected to each other, and each voltage target value setting unit observes the current control terminal and detects the voltage, and detects the current control terminal voltage and the current control terminal. The voltage control information for correcting the voltage target value of itself according to a difference from the voltage is output, and the main switching elements are turned on / off based on the corrected voltage target value of the plurality of units. The power supply system in which the output currents of the switching power supply apparatus are equalized.

  The power supply system according to claim 10 is the power supply system according to claim 9, wherein each voltage target value setting unit has a value obtained by subtracting the current control terminal voltage from the current control voltage. When the reference voltage (positive value) is greater than or equal to the reference voltage (positive value), the voltage control information for correcting and increasing the voltage target value is output; otherwise, the voltage target value is maintained. In this way, the power supply system outputs the voltage control information.

  The invention according to claim 11 is the power supply system according to claim 9, wherein each voltage target value setting unit has a value obtained by subtracting the current control terminal voltage from the current control voltage. Outputs the voltage control information indicating that the voltage target value is corrected and reduced when the voltage reference value is less than or equal to two reference values (negative values); otherwise, the voltage target value is maintained. In this way, the power supply system outputs the voltage control information.

  A power supply system according to a twelfth aspect is the power supply system according to the ninth aspect, wherein each voltage target value setting unit has a value obtained by subtracting the current control terminal voltage from the current control voltage. When the reference voltage (positive value) or more is output, the voltage control information for correcting and increasing the voltage target value is output, and when the reference value is less than or equal to the second reference value (negative value) The power supply system outputs the voltage control information for correcting and lowering the voltage target value, and otherwise outputs the voltage control information so that the voltage target value of itself is maintained. .

  The invention described in claim 13 is a power supply system using a plurality of the switching power supply devices according to claim 8, wherein the plurality of switching power supply devices are connected in parallel to each other, and the current control The terminals are connected to each other, one of the plurality is a master power supply, the other is a slave power supply, and the master power supply has a correction amount for correcting the voltage target value set to zero, and the slave power supply The correction amount when correcting the voltage target value is set to a value other than zero, and the voltage target value setting unit of each slave power supply observes its current control terminal and detects its voltage. When the value obtained by subtracting the current control terminal voltage from the current control voltage is equal to or greater than a first reference value (positive value), the voltage target of the self is set by the set correction amount. Value above Output the voltage control information to the effect that the voltage control information to lower the voltage target value by the amount of the set correction amount when the voltage control information is less than or equal to a second reference value (negative value). In other cases, the power supply system outputs the voltage control information so as to maintain the voltage target value of itself.

  The switching power supply device of the present invention can significantly reduce the number of parts of the circuit for controlling the output current as compared with the prior art. In addition, by providing a voltage target value setting unit in the digital processor, simply rewriting the program (correction parameters) cancels the current balance error caused by individual differences (characteristic variations) in the parts used, and It becomes possible to improve accuracy and freely adjust the gain and phase characteristics of the output current balance control. Further, when the switching power supply device is used alone, the switching power supply device is used as a constant current power supply by applying a predetermined DC voltage from the outside to the current control terminal to define the current control terminal voltage. It is also possible.

  Since the power supply system of the present invention has a configuration in which a plurality of the above-described switching power supply devices are prepared and operated in parallel, the output currents of the respective switching power supply devices are equalized with high accuracy, and at the same time, N + 1 redundant operation can be realized. In addition, if a switching power supply device in which a voltage target value setting unit is provided in the digital processor is used and a single program is rewritten and set to the master power supply, all the switching can be performed by changing the master power supply voltage target value. Master / slave operation is also possible in which the output voltage of the power supply is uniformly varied.

It is a circuit diagram showing a power supply system of a first embodiment of the present invention. It is a circuit diagram which shows the internal structure of the switching power supply device used for the power supply system of 1st embodiment. It is the graph (a) explaining the correction amount of the voltage control information which the voltage target value setting part of FIG. 2 outputs, and the graph (b) of a modification. It is a time chart explaining operation | movement of the pulse generator of FIG. It is the graph (a) explaining the current control information which the voltage target value setting part of FIG. 2 outputs, and the graph (b) of a modification. It is a flowchart explaining operation | movement of the power supply system of 1st embodiment. It is a circuit diagram which shows the internal structure of the switching power supply device used for the power supply system of 2nd embodiment of this invention. 8 is a graph (a) illustrating a correction amount of voltage control information output by the voltage target value setting unit in FIG. 7, and a graph (b) of a modification example. FIG. 8 is a circuit diagram (a) showing an internal configuration of the amplifier circuit of FIG. 7 and a circuit diagram (b) of a modified example. It is a flowchart explaining operation | movement of the power supply system of 2nd embodiment. It is a circuit diagram explaining the circuit operation | movement of the periphery of CB terminal in the power supply system of 2nd embodiment. It is a circuit diagram which shows the internal structure of the switching power supply device used for the power supply system of 3rd embodiment of this invention. It is the graph (a) explaining the correction amount of the voltage control information which the voltage target value setting part of FIG. 12 outputs, and the graph (b) of a modification. FIG. 13A is a circuit diagram showing an internal configuration of the amplifier circuit of FIG. 12 and FIG. It is a flowchart explaining operation | movement of the power supply system of 3rd embodiment. It is a circuit diagram explaining the circuit operation | movement of the periphery of CB terminal in the power supply system of 3rd embodiment. It is a circuit diagram which shows the internal structure of the switching power supply device used for the power supply system of 4th embodiment of this invention. It is a circuit diagram which shows the modification of an amplifier circuit. It is a circuit diagram explaining the modification of a current control voltage output part.

  Hereinafter, a first embodiment of a switching power supply device and a power supply system using the same according to the present invention will be described with reference to FIGS. As shown in FIG. 1, the power supply system 10 of this embodiment is a system that receives power supplied from one DC input power supply 12 and outputs a predetermined voltage and current to one load 14. Two switching power supply devices 16 are used. Hereinafter, if necessary, the number of the switching power supply device is numbered at the end of the reference number of the switching power supply device (1), (2) to distinguish, and other related components, Distinguish them by adding (1) and (2) to the end of the code.

  As illustrated in FIG. 2, the switching power supply device 16 includes a power conversion unit 18, a voltage detection circuit 20, a current detection circuit 22, and a control unit 24.

  The power conversion unit 18 intermittently turns on and off the main switching element 26 that intermittently supplies the DC input voltage Vi supplied between the IN terminals, which are a pair of input terminals, and the main switching element 26, and supplies the above intermittent voltage. A rectifying element 27 for rectifying, and an output smoothing circuit 28 that is a low-pass filter that smoothes the rectified voltage and outputs a DC output voltage Vo. Here, the main switching element 26 and the rectifying element 27 are both N-channel MOS FETs. The output smoothing circuit 28 is a low-pass filter composed of an inductor 28a and a capacitor 28b. Both ends of the capacitor 28b are drawn out to a pair of OUT terminals, which are output terminals, and the output voltage Vo is output to an externally connected load 14. Supply current Io. The output voltage Vo is determined by an on time and an off time when the switching element 26 is switched.

  The voltage detection circuit 20 is a circuit that detects the output voltage Vo or a voltage corresponding thereto. For example, two resistors are connected in series between a pair of OUT terminals, and a voltage generated at the midpoint is output as a self-voltage signal Va. As another method, an auxiliary winding is provided in the inductor 28a of the output smoothing circuit 28, and a method of obtaining the self-voltage signal Va using a voltage generated in the auxiliary winding is also conceivable.

  The current detection circuit 22 is a circuit that detects the output current Io or a current corresponding thereto. For example, a current detection resistor is inserted in a line connecting the capacitor 28b and the OUT terminal of the output smoothing circuit 28, and a voltage drop generated by the output current Io flowing is detected and output as a self-current signal Ia. As another method, a method is conceivable in which the switching current flowing through the main switching element 26 is converted into a voltage via a current transformer (or resistor), and the peak value or average value thereof is detected to obtain the self-current signal Ia.

  The control unit 24 is a circuit block that generates a drive pulse Vg that defines an on time and an off time of the main switching element 26 and controls on / off of the main switching element 26 with the drive pulse Vg. A voltage target value setting unit 32 and a current control voltage output unit 34 are provided.

  The drive pulse output unit 30 includes an error amplifier 30a that inverts and amplifies the difference between the self-voltage signal Va and a predetermined voltage target value Vr, and a triangular wave generation circuit 30b that outputs a reference triangular wave voltage having a constant period, and further includes an error. A comparator 30c that compares the output voltage of the amplifier 30a with the reference triangular wave voltage and performs pulse width modulation is provided. The drive pulse Vg is input to the drive terminal of the main switching element 26 through a buffer circuit or the like (not shown). The drive pulse output unit 30 variably adjusts the on-time and off-time of the drive pulse Vg so that the difference between the self-voltage signal Va and the predetermined voltage target value Vr is small, and outputs it to the main switching element.

  The drive pulse output unit 30 also has a function of driving the rectifying element 27, and is provided with an inverter 30d that outputs an inverted pulse obtained by reversing the logic of the drive pulse Vg. To the drive terminal of the rectifying element 27. When the rectifying element 27 is a diode element, a drive circuit is unnecessary and the inverter 30d can be omitted.

  Here, the voltage target value setting unit 32 is provided in the digital processor, outputs voltage control information Sv that defines the voltage target value Vr of the drive pulse output unit 30, and current control information Si corresponding to the self-current signal Ia. It has a function to output. The voltage target value setting unit 32 normally outputs voltage control information Sv indicating that the voltage target value Vr is set to the default value Vr0. Then, when the voltage (CB line voltage Vbm) of the current control line 36 (hereinafter referred to as the CB line 36) is detected and the predetermined condition shown in FIG. Voltage control information Sv indicating that Vr is changed by correction amounts Vk1 and Vk2 is output. The determination as to whether or not to correct the voltage target value Vr is repeated every time the CB line voltage Vbm is acquired (sampled). The voltage control information Sv and the current control information Si will be described in detail later.

  The current control voltage output unit 34 includes a pulse generator 38 that generates the pulse voltage V38 based on the current control information Si output from the voltage target value setting unit 32, and a smoothing circuit 40 that smoothes and outputs the pulse voltage V38. I have.

  The pulse generator 38 is provided in the digital processor in the same way as the voltage target value setting unit 32. Here, the cycle and the duty ratio are controlled by digital PWM configured by combining a clock, a counter, a pulse output circuit, and the like. The generated pulse voltage V38 is output. Hereinafter, the operation of the pulse generator 38 will be described with reference to FIG.

  A clock signal is supplied to the counter, and the counter counts the number of clocks. When the count value of the counter is reset to zero, the pulse voltage V38 that is the output of the pulse generator 38 becomes high level. After that, counting continues while the pulse voltage V38 is at the high level. When the count value reaches the first register setting value D1, the pulse voltage V38 changes to the low level, and the count value reaches the second register setting value D2. Then, the counter is reset and the pulse voltage V38 turns to high level. The pulse generator 38 generates a pulse voltage V38 that repeats a high level and a low level by repeating the above operation. Therefore, the cycle and duty ratio of the pulse voltage V38 can be determined by the first and second register set values D1 and D2. For example, when “D1 = 50, D2 = 100”, a pulse voltage V38 with a duty ratio of Duty = 0.5 is output.

  The pulse generator 38 generates a pulse having a low level of 0V and a high level of Vh (for example, 5V). The second register setting value D2 is fixed, and the cycle of the pulse voltage V38 is constant. The first register set value D1 is defined by the current control information Si output from the voltage target value setting unit 32, and the current control information Si changes corresponding to the self-current signal Ia detected by the current detection circuit 22. . Therefore, the duty ratio Duty of the pulse voltage V38 changes corresponding to the self current signal Ia. Here, as shown in FIG. 5A, the relationship between the self-current signal Ia and the duty ratio Duty (and current control information Si) is defined by a linear function, and when “Ia = 0A, Si = Duty = 0. “When Ia = 10 A, Si = Duty = 1.0”. Note that this relationship may be defined by a function other than the linear function. For example, as shown in FIG. 5B, a curved function may be used.

  The smoothing circuit 40 is a low-pass filter including a resistor 40a and a capacitor 40b. The positive output of the capacitor 40b is connected to the CB line 36. The CB line 36 is connected to the CB line 36 for current control. Terminals (hereinafter referred to as CB terminals) are provided. The smoothing circuit 40 smoothes the pulse voltage V38 to generate a DC voltage, and outputs it to the CB line 36. When the CB terminal is open, a DC current control voltage Vbo, which is obtained by multiplying the peak value Vh of the pulse voltage V38 by the duty ratio, is generated at the output of the smoothing circuit 40. The resistor 40a may be replaced with an inductor.

  Next, the voltage control information Sv output from the voltage target value setting unit 32 will be described. When the voltage target value setting unit 32 detects the CB line voltage Vbm and does not match the current control voltage Vbo (= Vh × Duty) to be generated based on the current control information Si, the voltage target value setting unit 32 determines the voltage according to the voltage difference. The voltage control information Sv for correcting the target value Vr is output.

  Here, as shown in FIG. 3A, when the voltage difference ΔVb (= Vbo−Vbm) is equal to or larger than the first reference value k1 (k1> 0), the immediately preceding voltage target value Vr is decreased by the correction amount Vk1. The voltage control information Sv indicating that it is to be output. When the voltage difference ΔVb is equal to or smaller than the second reference value −k2 (k2> 0), the voltage control information Sv indicating that the previous voltage target value Vr is increased by the correction amount Vk2 is output. In other cases, the voltage target value Vr is not corrected, and the voltage control information Sv is output so that the previous value is maintained. The determination of whether or not to correct the voltage target value Vr is repeated every time the CB line voltage Vbm is acquired (sampled).

  In general, the first and second reference values k1 and k2 may be set to the same value (for example, 0.1), and the correction amounts Vk1 and Vk2 may be set to the same value. In FIG. 3A, the correction amounts Vk1 and Vk2 are constant values in the range where the absolute value of the voltage difference ΔVb is equal to or larger than the reference values k1 and k2, but as shown in FIG. The correction amounts Vk1 and Vk2 may gradually increase as the absolute value of the voltage difference ΔVb increases.

  The power supply system 10 includes two switching power supply devices 16 (1) and 16 (2) described above, and IN (1) and IN (2) terminals are connected to both ends of the input power supply 12 as shown in FIG. The OUT (1) and OUT (2) terminals are connected in parallel with each other to the common load 14 and are configured to perform parallel operation. Further, the CB (1) and CB (2) terminals are also connected to each other. The load current Io (all) flowing into the load 14 is the sum of the output currents Io (1) and Io (2) of the switching power supply devices 16 (1) and 16 (2), and is always a constant value here. Suppose there is.

  Next, the operation of the power supply system 10 will be described based on the flowchart of FIG. Here, two switching power supplies 16 (1) and 16 (2) output a total load current Io (all) of 9A. In the initial state, one output current Io (1) is 5A and the other is It is assumed that the output current Io (2) is 4A and is not balanced.

  First, in each switching power supply device 16, the voltage target value setting unit 32 acquires the self-current signal Ia measured by the current detection circuit 22, and corresponds to the self-current signal Ia based on the relationship shown in FIG. Create control information Si. (Steps S11 and S12). Next, it is assumed that “the pulse generator 38 outputs a pulse voltage V38 generated based on the control information Si in a state where the CB terminal is open”. In this case, the DC voltage to be output from the smoothing circuit 40 is assumed. The current control voltage Vbo is predicted and calculated (step S13).

  In the case of the switching power supply 16 (1), since the output current Io (1) = Ia (1) = 5A, the current control information Si (1) indicating that the first register set value D1 of the pulse generator 38 (1) is set to 50. 1) is created (steps S11 and S12). Assuming that "the pulse voltage V38 (1) having a peak value Vh = 5V and a duty ratio = 0.5 is output from the pulse generator 38 (1) with the CB (1) terminal open", As the current control voltage Vbo (1), 2.5V obtained by multiplying the peak value Vh by the duty ratio Duty is calculated (step S13).

  On the other hand, in the case of the switching power supply 16 (2), since the output current Io (2) = Ia (2) = 4A, the current control information indicating that the first register setting value D1 of the pulse generator 38 (2) is 40. Si (2) is created (steps S11 and S12). Assuming that "the pulse voltage V38 (2) with a peak value Vh = 5V and a duty ratio = 0.4 was output from the pulse generator 38 (2) with the CB (2) terminal open" As the current control voltage Vbo (2), 2.0V is calculated by multiplying the peak value Vh by the duty ratio Duty (step S13).

  Next, the voltage target value setting unit 32 of each switching power supply device 16 outputs the current control information Si created in step S12, the pulse voltage V38 generated by the pulse generator 38 is smoothed by the smoothing circuit 40, and the CB line Is output to 36. (Step S14). As a result, since the CB (1) terminal and the CB (2) terminal are connected to each other, the CB line voltages Vbm (1) and Vbm (2) are equal, and the voltage value is equal to the current control voltage Vbo ( The average value of 1) = 2.5V and Vbo (2) = 2.0V is 2.25V.

  Next, in each switching power supply device 16, the voltage target value setting unit 32 detects the CB line voltage Vbm and compares it with the current control voltage Vbo calculated in step S13 (steps S15 and S16). In the case of the switching power supply device 16 (1), ΔVb (1) = Vbo (1) −Vbm (1) = 0.25V, which is larger than k1 = 0.1, and therefore satisfies the condition A1. On the other hand, in the case of the switching power supply device 16 (2), ΔVb (2) = Vbo (2) −Vbm (2) = − 0.25V, which is smaller than −k2 = −0.1, and therefore satisfies the condition A2.

  Next, since the switching power supply 16 (1) satisfies the condition A1, the process proceeds to step S17, and the voltage target value setting unit 32 (1) sets the previous voltage target value Vr based on the relationship of FIG. The voltage control information Sv1 (1) for reducing the correction amount Vk1 is created and output. As a result, the ON time of the main switching element 26 (1) is shortened, the output current Io (1) is reduced, and the initial 5A becomes, for example, 4.8A.

  On the other hand, since the switching power supply 16 (2) satisfies the condition A2, the process proceeds to step S18, and the voltage target value setting unit 32 (2) corrects the immediately preceding voltage target value Vr based on the relationship of FIG. Create and output voltage control information Sv1 (2) to reduce the amount by Vk2. As a result, the on-time of the main switching element 26 (2) becomes longer, the output current Io (2) increases, and the initial 4A becomes 4.2A, for example. The load current Io (all) is constant at 9A.

  After that, while repeating the above steps S11 to S18 several times, the output current Io (1) gradually decreases from 5A, the output current Io (2) gradually increases from 4A, and eventually the switching power supply device 16 ( 1) and 16 (2) both satisfy the condition B, and the output currents Io (1) and Io (2) converge to about 4.5A and are balanced, and the switching power supply devices 16 (1) and 16 ( The burden of 2) is almost equalized.

  Here, the accuracy of the output current balance will be described. As can be seen from the graph of FIG. 3A, when k1 and k2 which are absolute values of the first specified value and the second specified value are reduced, steps S17 and S18 are performed even when the voltage difference ΔVb is small. Therefore, the accuracy of current balance can be relatively increased. However, if it is made too small, there is a possibility that new adverse effects may occur such as the time until the output currents Io (1) and Io (2) converge. In addition, if there are variations in the characteristics of the internal elements of the switching power supply 16, the accuracy of the output current balance deteriorates. However, this problem is tested after the switching power supply 16 is assembled, The degree of characteristic variation is measured, and the program recorded in the voltage target value setting unit 32 may be rewritten as necessary (for example, the characteristic relating to the voltage control information Sv shown in FIG. 3 for correcting the acquired self-current signal Ia). The characteristic relating to the current control information Si shown in FIG. 5 is corrected). When the voltage target value setting unit is provided in the digital processor, the calibration can be performed only by changing the software, and the accuracy of the output current balance can be easily ensured.

  Further, the balance control speed increases as the correction amounts Vk1 and Vk2 in FIG. 3A are increased, since the balance control gain increases. However, it should be noted that if the value is too large, the balance control system may oscillate. In this case, as shown in FIG. 3B, when the absolute value of ΔVb is large, the correction amounts Vk1 and Vk2 are set large, and when the absolute value of ΔVb decreases, the correction amounts Vk1 and Vk2 are set small. By doing so, the output currents Io (1) and Io (2) can be converged gently, so that the speed of balance control can be increased while avoiding the oscillation problem.

  As described above, the switching power supply device 16 can significantly reduce the number of parts constituting the output current control circuit as compared with the conventional case. In addition, since the voltage target value setting unit 32 is provided in the digital processor, simply rewriting the program cancels the individual differences of the parts used and improves the control accuracy of the output current Io, and the current control gain and phase. The characteristics can be adjusted freely. In addition, when the switching power supply 16 is used alone, the switching power supply 16 is used as a constant current power supply by applying a predetermined DC voltage from the outside to the CB terminal to define the CB line voltage Vbm. Is also possible.

  In addition, since the power supply system 10 is configured to prepare two switching power supply devices 16 and operate in parallel, the output current Io of each switching power supply device 16 is equalized with high accuracy. Even when the number of parallel units is three or more, the balance control of the output current Io is performed in the same manner as described above, and at the same time, N + 1 redundant operation can be realized.

  Next, a switching power supply device according to a second embodiment of the present invention and a power supply system using the same will be described with reference to FIGS. Here, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The power supply system of the second embodiment has substantially the same configuration as the power supply system 10 of FIG. 1, but two switching power supply devices 42 of the second embodiment are used instead of the switching power supply device 16 described above.

  As shown in FIG. 7, the switching power supply 42 is provided with a voltage target value setting unit 44 instead of the voltage target value setting unit 32, and a current control voltage output unit instead of the current control voltage output unit 34. 46 is provided. Other configurations are the same. Hereafter, the part from which a structure differs is demonstrated.

  Here, the voltage target value setting unit 44 is provided in the digital processor, outputs voltage control information Sv that defines the voltage target value Vr of the drive pulse output unit 30, and current control information Si corresponding to the self-current signal Ia. It has a function to output. The voltage target value setting unit 44 normally outputs voltage control information Sv for setting the voltage target value Vr to the default value Vr0. Then, voltage control information indicating that the voltage CB line 36 (CB line voltage Vbm) is detected and the previous voltage target value Vr is changed by the correction amount Vk2 when the predetermined condition shown in FIG. 8A is satisfied. Sv is output. The determination as to whether or not to correct the voltage target value Vr is repeated every time the CB line voltage Vbm is acquired (sampled). The voltage control information Sv will be described in detail later. The current control information Si is the same as described above.

  The current control voltage output unit 46 generates a pulse voltage V38 based on the current control information Si output from the voltage target value setting unit 44, a smoothing circuit 40 that smoothes and outputs the pulse voltage V38, An amplifying circuit 48 for amplifying the output of the smoothing circuit 40 is provided. In other words, in addition to the configuration of the current control voltage output unit 34, an amplifier circuit 48 is newly provided.

  The amplifier circuit 48 is a kind of emitter follower. As shown in FIG. 9A, an NPN output transistor 50 having a base connected to the output terminal of the smoothing circuit 40 and a collector connected to the DC power source Vcc, The output resistor 50 is connected between the emitter of the output transistor 50 and the ground, and the emitter of the output transistor 50 is connected to the CB line 36. Therefore, if the base-emitter saturation voltage of the output transistor 50 is small and ignored, the amplifier circuit 48 can output the DC current control voltage Vbo output from the smoothing circuit 40 toward the CB line 36 ( Voltage amplification factor is 1). When the temperature compensation is performed by canceling the influence of the base-emitter saturation voltage of the output transistor 50, as shown in FIG. 9B, the PNP auxiliary transistor 54 and the auxiliary resistor are provided on the base side of the output transistor 50. 56 may be provided.

  Next, the voltage control information Sv output from the voltage target value setting unit 44 will be described. When the voltage target value setting unit 44 detects the CB line voltage Vbm and does not match the current control voltage Vbo (= Vh × Duty) to be generated based on the current control information Si, the voltage target value setting unit 44 determines the voltage according to the voltage difference. The voltage control information Sv for correcting the target value Vr is output.

  Here, as shown in FIG. 8A, when the voltage difference ΔVb is equal to or smaller than the second reference value −k2 (k2> 0), the voltage control for increasing the immediately preceding voltage target value Vr by the correction amount Vk2. Outputs information Sv. In other cases, the voltage target value Vr is not corrected, and the voltage control information Sv is output so that the previous value is maintained. The determination of whether or not to correct the voltage target value Vr is repeated every time the CB line voltage Vbm is acquired (sampled).

  As shown in FIG. 8B, the correction amount Vk2 may gradually increase as the voltage difference ΔVb increases in the negative direction. In the case of the switching power supply 42, since the voltage difference ΔVb does not become a positive value, the first reference value k1 and the correction amount Vk1 are not defined.

  The power supply system of the second embodiment is composed of two switching power supply devices 42 (1) and 42 (2) described above, and the IN (1) and IN (2) terminals are input power supply 12 as in FIG. The OUT (1) and OUT (2) terminals are connected in parallel to the common load 14 to perform parallel operation. Further, the CB (1) and CB (2) terminals are also connected to each other. The load current Io (all) flowing into the load 14 is the sum of the output currents Io (1) and Io (2) of the switching power supply devices 42 (1) and 42 (2), and is always a constant value here. Suppose there is.

  Next, the operation of this power supply system will be described based on the flowchart of FIG. Here, the two switching power supplies 42 (1) and 42 (2) output a total load current Io (all) of 9A. In the initial state, one output current Io (1) is 5A and the other It is assumed that the output current Io (2) is 4A and is not balanced. The base-emitter saturation voltage of the output transistors 50 (1) and 50 (2) is ignored because it is sufficiently small.

  Each step of the flowchart of FIG. 10 is denoted by the same reference numeral for the same step as the flowchart of FIG. 6 described above, and the difference is that “step S17 in the case of condition A1” is deleted. is there. Hereinafter, each step will be described in order.

  First, steps S11 and S12 are performed. In the case of the switching power supply 42 (1), since the output current Io (1) = Ia (1) = 5A, based on the relationship of FIG. Current control information Si (1) for setting the first register set value D1 of 1) to 50 is created. Assuming that "the pulse voltage V38 (1) having a peak value Vh = 5V and a duty ratio = 0.5 is output from the pulse generator 38 (1) with the CB (1) terminal open", As the current control voltage Vbo (1), 2.5V obtained by multiplying the peak value Vh by the duty ratio Duty is calculated (step S13).

  On the other hand, in the case of the switching power supply 42 (2), since the output current Io (2) = Ia (2) = 4A, the current control information indicating that the first register set value D1 of the pulse generator 38 (2) is 40. Si (2) is created (steps S11 and S12). Assuming that "the pulse voltage V38 (2) having a peak value Vh = 5V and a duty ratio = 0.5 was output from the pulse generator 38 (2) with the CB (2) terminal open" As the current control voltage Vbo (2), 2.0V is calculated by multiplying the peak value Vh by the duty ratio Duty (step S13).

  Next, the voltage target value setting unit 44 of each switching power supply device 42 outputs the current control information Si created in step S12, the pulse voltage V38 generated by the pulse generator 38 is smoothed by the smoothing circuit 40, and the amplification circuit Output to the CB line 36 via 48 is enabled. (Step S14).

  Since the amplifier circuits 48 (1) and 48 (2) have the CB (1) terminal and the CB (2) terminal connected to each other, as shown in FIG. 11, only the output transistor 50 (1) having a high base potential is provided. Is conducted. Therefore, only the current control voltage Vbo (1) = 2.5V on the transistor 50 (1) side appears on the CB lines 36 (1) and 36 (2), and both the CB line voltages Vbm (1) and Vbm (2) are 2.5. V. At this time, all currents flowing through the output resistors 52 (1) and 52 (2) are supplied from the DC power source Vcc (1) through the output transistor 50 (1).

  Next, steps S15 and S16 are performed, and each voltage target value setting unit 44 detects the CB line voltage Vbm and compares it with the current control voltage Vbo calculated in step S13. In the case of the switching power supply device 16 (2), ΔVb (2) = Vbo (2) −Vbm (2) = − 0.5V, which is smaller than −k2 = −0.1, and therefore satisfies the condition A2. On the other hand, in the case of the switching power supply 42 (1), ΔVb (1) = Vbo (1) −Vbm (1) ≈0V, which is larger than −k2 = −0.1, and therefore satisfies the condition B.

  Next, since the switching power supply 42 (2) satisfies the condition A2, the process proceeds to step S18, and the voltage target value setting unit 44 (2) sets the previous voltage target value Vr based on the relationship of FIG. The voltage control information Sv1 (2) for increasing the correction amount Vk2 is created and output. As a result, the on-time of the main switching element 26 (2) becomes longer, the output current Io (2) increases, and the initial 4A becomes 4.1A, for example.

  On the other hand, since the switching power supply 42 (1) satisfies the condition B, the voltage target value setting unit 44 (1) does not correct the voltage target value Vr based on the relationship of FIG. To maintain. Therefore, the operation of spontaneously changing the output current Io (1) is not performed. However, the load current Io (all) is constant at 9A, and since the output current Io (2) is responsible for 4.1A of 9A, the output current Io (1) is passively reduced to 4.9A. .

  After that, while repeating the above steps S11 to S16, S18 several times, the output current Io (1) gradually decreases from 5A, the output current Io (2) gradually increases from 4A, and eventually the switching power supply device 42 (1) and 42 (2) both satisfy the condition B, and the output currents Io (1) and Io (2) converge and balance to about 4.5A, respectively, and the switching power supply 42 (1) 42 (2) is almost equalized.

  As described above, the switching power supply device 42 and the power supply system using the same according to the second embodiment can obtain the same operational effects as the switching power supply device 16 and the power supply system 10 described above, and are further operated in parallel. There is an advantage that even when the number of the switching power supply devices 42 is large, it can be easily handled. For example, when the switching power supply device 16 of the first embodiment is operated in parallel, one specific current control voltage output unit 34 (k) is connected to all other current control voltage output units 34 (2) to 34 (n ) In order to keep the load per unit below a certain level, it is necessary to limit the number n in parallel operation. On the other hand, in the case of the switching power supply 42 and a power supply system using the same, the current amplification operation of the amplifier circuit 48 can cope with a large number n of parallel operations.

  Further, since this power supply system is controlled only in the direction in which the latest voltage (output voltage Vo) of the load 14 increases, it is advantageous when the load 14 does not like a transient voltage drop. For example, in the case of the power supply system 10 of the first embodiment, since the switching power supply device 16 has a function of reducing the output voltage Vo, if a disturbance enters the current balance control system in the process of performing the current balance control ( For example, when noise enters the CB line 36), the output voltage Vo may be unnecessarily lowered and adversely affect the load 14. On the other hand, the power supply system of this embodiment is safe because the output voltage Vo does not decrease even if this type of disturbance occurs.

  In the case of a power supply system using the switching power supply 42, the balance control is converged as compared with the power supply system 10 in FIG. 1 because the output current Io is mainly controlled only by one switching power supply 42. The time until is relatively long. In this regard, as described above, it is preferable to increase the speed of control by increasing the correction amount Vk2 and increasing the gain of balance control.

  Next, a switching power supply device according to a third embodiment of the present invention and a power supply system using the same will be described with reference to FIGS. Here, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The power supply system of the third embodiment has substantially the same configuration as the power supply system 10 of FIG. 1, but two switching power supply devices 58 of the third embodiment are used instead of the switching power supply device 16 described above.

  As shown in FIG. 12, the switching power supply 58 is provided with a voltage target value setting unit 60 in place of the voltage target value setting unit 32, and a current control voltage output unit in place of the current control voltage output unit 34. 62 is provided. Other configurations are the same. Hereafter, the part from which a structure differs is demonstrated.

  Here, the voltage target value setting unit 60 is provided in the digital processor, outputs voltage control information Sv that defines the voltage target value Vr of the drive pulse output unit 30, and current control information Si corresponding to the self-current signal Ia. It has a function to output. The voltage target value setting unit 60 normally outputs voltage control information Sv indicating that the voltage target value Vr is set to the default value Vr0. Then, the voltage control information indicating that the voltage (CB line voltage Vbm) of the CB line 36 is detected and the immediately preceding voltage target value Vr is changed by the correction amount Vk1 when the predetermined condition shown in FIG. Sv is output. The determination as to whether or not to correct the voltage target value Vr is repeated every time the CB line voltage Vbm is acquired (sampled). The voltage control information Sv will be described in detail later. The current control information Si is the same as described above.

  The current control voltage output unit 62 includes a pulse generator 38 that generates the pulse voltage V38 based on the current control information Si output from the voltage target value setting unit 60, a smoothing circuit 40 that smoothes and outputs the pulse voltage V38, An amplifier circuit 64 that amplifies the output of the smoothing circuit 40 is provided. That is, in addition to the configuration of the current control voltage output unit 34, an amplifier circuit 64 is newly provided.

  The amplifier circuit 64 is a kind of emitter follower, and as shown in FIG. 14A, a PNP output transistor 66 having a base connected to the output terminal of the smoothing circuit 40 and a collector connected to the ground, and an output transistor 66, and an output resistor 68 connected between the DC power source Vcc and the emitter of the output transistor 66 is connected to the CB line 36. Therefore, if the base-emitter saturation voltage of the output transistor 66 is small and ignored, the amplifier circuit 64 can output the DC current control voltage Vbo output from the smoothing circuit 40 toward the CB line 36 ( Voltage amplification factor is 1). When the temperature compensation is performed by canceling the influence of the base-emitter saturation voltage of the output transistor 66, an NPN auxiliary transistor 70 and an auxiliary resistor are provided on the base side of the output transistor 66 as shown in FIG. 72 may be provided.

  Next, the voltage control information Sv output by the voltage target value setting unit 60 will be described. The voltage target value setting unit 66 detects the CB line voltage Vbm, and if it does not match the current control voltage Vbo (= Vh × Duty) to be generated based on the current control information Si, the voltage target value setting unit 66 determines the voltage according to the voltage difference. The voltage control information Sv for correcting the target value Vr is output.

  Here, as shown in FIG. 13A, when the voltage difference ΔVb is equal to or larger than the first reference value k1 (k1> 0), the voltage control information indicating that the immediately preceding voltage target value Vr is decreased by the correction amount Vk1. Sv is output. In other cases, the voltage target value Vr is not corrected, and the voltage control information Sv is output so that the previous value is maintained. The determination of whether or not to correct the voltage target value Vr is repeated every time the CB line voltage Vbm is acquired (sampled).

  As shown in FIG. 13B, the correction amount Vk1 may gradually increase as the voltage difference ΔVb increases in the positive direction. In the case of the switching power supply device 58, since the voltage difference ΔVb does not become a negative value, the second reference value k2 and the correction amount Vk2 are not defined.

  The power supply system of the third embodiment is composed of two switching power supply devices 58 (1) and 58 (2) described above, and the IN (1) and IN (2) terminals are input power supplies 12 as in FIG. The OUT (1) and OUT (2) terminals are connected in parallel to the common load 14 to perform parallel operation. Further, the CB (1) and CB (2) terminals are also connected to each other. The load current Io (all) flowing into the load 14 is a sum of the output currents Io (1) and Io (2) of the switching power supply devices 58 (1) and 58 (2), and is always a constant value here. Suppose there is.

  Next, the operation of this power supply system will be described based on the flowchart of FIG. Here, two switching power supplies 58 (1) and 58 (2) output a total load current Io (all) of 9A, and in the initial state, one output current Io (1) is 5A and the other It is assumed that the output current Io (2) is 4A and is not balanced. Further, the base-emitter saturation voltages of the output transistors 66 (1) and 66 (2) are ignored because they are sufficiently small.

  In the steps of the flowchart of FIG. 15, the same steps as those in the flowchart of FIG. 6 described above are denoted by the same reference numerals, and the difference is that “step S18 in the case of condition A2” is deleted. is there. Hereinafter, each step will be described in order.

  First, steps S11 and S12 are performed. In the case of the switching power supply 58 (1), since the output current Io (1) = Ia (1) = 5A, based on the relationship of FIG. Current control information Si (1) for setting the first register set value D1 of 1) to 50 is created. Assuming that "the pulse voltage V38 (1) having a peak value Vh = 5V and a duty ratio = 0.5 is output from the pulse generator 38 (1) with the CB (1) terminal open", As the current control voltage Vbo (1), 2.5V obtained by multiplying the peak value Vh by the duty ratio Duty is calculated (step S13).

  On the other hand, in the case of the switching power supply 58 (2), since the output current Io (2) = Ia (2) = 4A, the current control information indicating that the first register set value D1 of the pulse generator 38 (2) is 40. Si (2) is created (steps S11 and S12). Assuming that "the pulse voltage V38 (2) having a peak value Vh = 5V and a duty ratio = 0.5 was output from the pulse generator 38 (2) with the CB (2) terminal open" As the current control voltage Vbo (2), 2.0V is calculated by multiplying the peak value Vh by the duty ratio Duty (step S13).

  Next, the voltage target value setting unit 60 of each switching power supply 58 outputs the current control information Si created in step S12, the pulse voltage V38 generated by the pulse generator 38 is smoothed by the smoothing circuit 40, and the amplifier circuit It becomes possible to output to the CB line 36 via 64. (Step S14).

  In the amplifier circuits 64 (1) and 64 (2), since the CB (1) terminal and the CB (2) terminal are connected to each other, as shown in FIG. 16, only the output transistor 66 (2) having a low base potential is provided. Is conducted. Therefore, only the current control voltage Vbo (2) = 2.0V on the transistor 66 (2) side appears on the CB lines 36 (1) and 36 (2), and both the CB line voltages Vbm (1) and Vbm (2) are 2.0. V. At this time, all of the current flowing through the output resistors 68 (1) and 68 (2) flows into the amplifier circuit 64 (2) as the collector current of the output transistor 66 (2).

  Next, steps S15 and S16 are performed, and each voltage target value setting unit 60 detects the CB line voltage Vbm and compares it with the current control voltage Vbo calculated in step S13. In the case of the switching power supply device 16 (1), ΔVb (1) = Vbo (1) −Vbm (1) = 0.5V, which is larger than k1 = 0.1, and therefore satisfies the condition A1. On the other hand, in the case of the switching power supply 58 (2), ΔVb (2) = Vbo (2) −Vbm (2) ≈0V, which is smaller than k1 = 0.1, so the condition B is satisfied.

  Next, since the switching power supply 58 (1) satisfies the condition A1, the process proceeds to step S17, and the voltage target value setting unit 60 (1) sets the previous voltage target value Vr based on the relationship of FIG. The voltage control information Sv1 (1) for reducing the correction amount Vk1 is created and output. As a result, the ON time of the main switching element 26 (1) is shortened, the output current Io (1) is reduced, and the initial 5A becomes, for example, 4.9A.

  On the other hand, since the switching power supply 58 (2) satisfies the condition B, the voltage target value setting unit 60 (2) does not correct the voltage target value Vr based on the relationship shown in FIG. To maintain. Therefore, the operation for spontaneously changing the output current Io (2) is not performed. However, the load current Io (all) is constant at 9A, and since the output current Io (1) takes charge of 4.9A of 9A, the output current Io (2) increases passively to 4.1A. .

  After that, while repeating the above steps S11 to S17 several times, the output current Io (1) gradually decreases from 5A, the output current Io (2) gradually increases from 4A, and eventually the switching power supply 58 ( 1) and 58 (2) both satisfy the condition B, and the output currents Io (1) and Io (2) are converged and balanced to about 4.5A, respectively, and the switching power supply devices 58 (1) and 58 The burden of (2) is almost equalized.

  As described above, the switching power supply 58 according to the third embodiment and the power supply system using the same can obtain the same effects as the switching power supply 42 according to the second embodiment and the power supply system using the same. .

  Further, since this power supply system is controlled only in the direction in which the latest voltage (output voltage Vo) of the load 14 decreases, it is advantageous when the load 14 dislikes a transient voltage increase. For example, in the case of the power supply system of another embodiment, since the switching power supply devices 16 and 42 have a function of increasing the output voltage Vo, if a disturbance enters the current balance control system (for example, noise in the CB line 36). The output voltage Vo may rise unnecessarily and adversely affect the load 14. On the other hand, in the case of the power supply system according to this embodiment, even if this kind of disturbance occurs, the output voltage Vo does not increase, so it is safe.

  Next, a switching power supply device according to a fourth embodiment of the present invention and a power supply system using the same will be described with reference to FIG. Here, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The power supply system of the fourth embodiment has substantially the same configuration as that of the power supply system 10 of FIG. 1, but two switching power supply devices 74 of the fourth embodiment are used instead of the switching power supply device 16 described above.

  As shown in FIG. 17, the switching power supply 74 includes a voltage target value setting unit 76 instead of the voltage target value setting unit 32, and a current control voltage output unit instead of the current control voltage output unit 34. 78 is provided. Other configurations are the same. Hereafter, the part from which a structure differs is demonstrated.

  Here, the voltage target value setting unit 78 is provided in the digital processor, outputs voltage control information Sv that defines the voltage target value Vr of the drive pulse output unit 30, and current control information Si corresponding to the self-current signal Ia. It has a function to output. Similarly to the voltage target value setting unit 32, the voltage target value setting unit 78 outputs voltage control information Sv based on the relationship of FIG. On the other hand, the current control information Si is information that directly designates a current control voltage Vbo to be generated by a current control voltage output unit 78 described later.

  The current control voltage output unit 78 is a digital / analog converter that converts the current control information Si, which is a digital signal output from the voltage target value setting unit 32, into a DC voltage (current control voltage Vbo) and outputs the converted voltage. As shown in FIG. 17, it is represented by an ideal digital-analog converter 17a and an output impedance 78b. The digital / analog converter 78a generates a current control voltage Vbo corresponding to (eg, proportional to) the self-current signal Ia based on the current control information Si, and is directed toward the CB line 36 via a predetermined output impedance 78a. Output.

  The power supply system of the fourth embodiment is composed of two switching power supply devices 74 (1) and 74 (2) described above, and the IN (1) and IN (2) terminals are input power supply 12 as in FIG. The OUT (1) and OUT (2) terminals are connected in parallel to the common load 14 to perform parallel operation. Further, the CB (1) and CB (2) terminals are also connected to each other.

  In this power supply system, the balance control of the output currents Io (1) and Io (2) is performed according to the flowchart of FIG.

  As described above, the switching power supply device 74 and the power supply system using the same according to the fourth embodiment can obtain the same effects as the switching power supply device 16 and the power supply system 10 described above.

  The switching power supply device of the present invention is not limited to the above embodiment. For example, the power conversion circuit is not limited to a step-down chopper converter, but may be another chopper converter, a single-ended forward converter, a flyback converter, or a bridge converter. Further, it may be either a DC-DC converter or an AC-DC converter, and may be an input / output insulation type or a non-insulation type. However, in the case of the input / output insulation type, each part in the control unit, the voltage detection circuit, and the current detection circuit are insulated by dividing them into an input side block and an output side block, respectively, and signals and information between the input side and the output side block These exchanges may be performed through signal transmission elements (eg, photocouplers, photorelays, transformers, capacitors, etc.) whose inputs and outputs are insulated.

  Further, the drive pulse output unit of the switching power supply apparatus may be configured to perform pulse width modulation by analog signal processing like the drive pulse output unit 30, but may be configured to perform pulse width modulation by digital signal processing. Absent.

  2 uses the voltage target value setting unit 32 that operates based on the relationship shown in FIG. 3A or FIG. 3B, the FIG. 8A or FIG. It can replace with the voltage target value setting part 44 which operate | moves based on the relationship of (b). In this case, the power supply system 10 of the first embodiment performs output current balance control according to the flowchart of FIG. Similarly, the voltage target value setting unit 32 can be replaced with a voltage target value setting unit 60 that operates based on the relationship shown in FIG. 13 (a) or FIG. 13 (b). In this case, the power supply system 10 of the first embodiment performs output current balance control according to the flowchart of FIG.

  7 uses the voltage target value setting unit 44 that operates based on the relationship shown in FIG. 8A. The voltage target that operates based on the relationship shown in FIG. The value setting unit 32 can be replaced. In this case, since the voltage difference ΔVb does not become a positive value due to the provision of the amplifier circuit 48, the operation as the switching power supply device 42 is substantially the same. Similarly, the switching power supply 58 of FIG. 12 uses the voltage target value setting unit 60 that operates based on the relationship of FIG. 13A, but the voltage that operates based on the relationship of FIG. The target value setting unit 32 can be replaced. In this case, since the voltage difference ΔVb does not become a negative value due to the provision of the amplifier circuit 64, the operation as the switching power supply device 58 is substantially the same. Therefore, also in the case of the power supply system replaced with the voltage target value setting unit 32, the output current balance control is performed according to the flowcharts of FIGS.

  The amplifier circuit is not limited to the emitter follower such as the amplifier circuits 48 and 64 described above, and may be configured using an operational amplifier or the like. For example, the amplifier circuit 80 illustrated in FIG. 18 is a voltage follower with a backflow prevention function configured by an operational amplifier and a diode, and can realize the same function and operation as the amplifier circuit 48 configured by a transistor or the like.

  Further, the switching power supply device 74 of FIG. 17 has a configuration in which the current control voltage output unit 78 has a configuration in which the digital / analog converter 78a outputs the current control voltage Vbo via the output impedance 78b. As shown, the digital / analog converter 78a may be changed to a configuration in which the current control voltage Vbo is output via the amplifier circuit 82. The amplifier circuit 82 may be the same as the amplifier circuits 48, 64, 80, etc., for example.

  In addition, a power supply system that operates the switching power supply device 16 of FIG. 2 in parallel is configured. One specific unit is set to “correction amounts Vk1, Vk2 = 0” to be a master power supply, and the other is set to “correction amounts Vk1, Vk2 = By setting a value other than zero to a slave power supply, so-called master / slave operation becomes possible. In the master power supply, the voltage target value Vr is maintained at the default value Vr0, so that the output voltage Vo is held at a constant value determined based on the default value Vr0. Each slave power supply changes its own voltage target value Vr to balance the output currents of all switching power supply devices (master power supply and slave power supply). As a result, the output voltage Vo of each slave power supply is It approaches the output voltage Vo. Therefore, by rewriting the default value Vr0 recorded in the voltage target value setting unit 32 of the master power supply, the output voltages Vo of all the switching power supply devices can be uniformly varied.

  Further, when the amplifier circuit as shown in FIG. 9A or FIG. 14A is used, if the value of the base-emitter saturation voltage and the temperature characteristic of the transistor cannot be ignored, the current control voltage Vbo is predicted. In this case, the prediction calculation may be performed in a form including the influence of the base-emitter saturation voltage.

DESCRIPTION OF SYMBOLS 10 Power supply system 16,42,58,74 Switching power supply device 18 Power conversion part 20 Voltage detection circuit 22 Current detection circuit 24 Control part 26 Main switching element 30 Drive pulse output part 32,44,60,76 Voltage target value setting part 34 , 46, 62, 78 Current control voltage output unit 36 CB line 38 Pulse generator 40 Smoothing circuit 48, 64, 80, 82 Amplifier circuit

Claims (13)

A power conversion unit that converts a DC or AC input voltage supplied to the input terminal by a switching operation of the main switching element and supplies an output voltage and an output current to a load connected to the output terminal, and the main switching element is turned on In a switching power supply comprising: a drive pulse that defines a time and an off time; and a control unit that controls on / off of the main switching element using the drive pulse,
A voltage detection circuit for detecting the output voltage or a voltage corresponding thereto and outputting a self-voltage signal; and a current detection circuit for detecting the output current or a current corresponding thereto and outputting a self-current signal;
The control unit generates the drive pulse so that a difference between the self-voltage signal and a predetermined voltage target value is small, and outputs the drive pulse to the main switching element, and the drive pulse output A voltage target value setting unit that outputs voltage control information that defines the voltage target value of the unit, and that outputs current control information corresponding to the self-current signal; and a DC current control voltage corresponding to the current control information. A current control voltage output unit that generates and outputs, and a current control terminal that enables the output of the current control voltage output unit to be connected to the outside;
The voltage target value setting unit detects the voltage of the current control terminal, and if the voltage control value does not match the current control voltage to be generated based on the current control information, the voltage target value setting unit sets the voltage target value according to the voltage difference. The voltage control information to be corrected is output, and the main switching element is turned on / off based on the corrected voltage target value, whereby the current control voltage to be generated based on the current control information is A switching power supply device, characterized by approaching a terminal voltage and reducing the voltage difference to a certain value or less.   The current control voltage output unit is a smoothing that is a pulse generation circuit that outputs a pulse voltage that repeats a high level and a low level at a constant period, and a low-pass filter that smoothes the pulse voltage and converts it into the DC current control voltage 2. The switching power supply device according to claim 1, wherein the pulse generation circuit determines a time ratio between the high level and the low level of the pulse voltage based on the current control information.   The current control voltage output unit is a smoothing that is a pulse generation circuit that outputs a pulse voltage that repeats a high level and a low level at a constant period, and a low-pass filter that smoothes the pulse voltage and converts it into the DC current control voltage A circuit and an amplifier circuit having an input terminal connected to the output of the smoothing circuit and an output terminal connected to the current control terminal, and the pulse generation circuit is configured to generate the pulse voltage based on the current control information. 2. The switching power supply device according to claim 1, wherein a ratio between the high level and the low level is determined.   The switching power supply device according to claim 3, wherein the amplifier circuit is an emitter follower circuit.   2. The switching power supply according to claim 1, wherein the current control voltage output unit is a digital-analog converter that outputs the DC current control voltage corresponding to the current control information, which is a digital signal, via a predetermined output impedance. apparatus.   The current control voltage output unit includes a digital-analog converter that outputs the DC current control voltage corresponding to the current control information that is a digital signal, and an input terminal connected to an output of the digital-analog converter. 2. The switching power supply device according to claim 1, comprising an amplifier circuit having an end connected to the current control terminal.   The switching power supply device according to claim 6, wherein the amplifier circuit is an emitter follower circuit.   The voltage target value setting unit is provided in the digital processor, and can change the voltage target value and the correction amount for correcting the voltage target value by rewriting a program recorded in the digital processor. The switching power supply device according to claim 1. A power supply system using a plurality of the switching power supply devices according to any one of claims 1 to 7, wherein the plurality of switching power supply devices have the output terminals connected in parallel to each other, and the current control terminals are connected to each other. Connected to each other,
Each voltage target value setting section detects its current control terminal and detects its voltage, and determines its voltage target according to the difference between its current control terminal voltage and its current control voltage. The voltage control information for correcting the value is output, and the main switching elements are turned on / off based on the corrected voltage target value, thereby equalizing the output currents of the plurality of switching power supply devices. Power supply system characterized by being made.   Each voltage target value setting unit, when a value obtained by subtracting its current control terminal voltage from its own current control voltage is equal to or greater than a first reference value (positive value), 10. The power supply system according to claim 9, wherein the voltage control information for correcting and increasing the voltage is output, and in other cases, the voltage control information is output so that the voltage target value of itself is maintained.   Each voltage target value setting unit, when a value obtained by subtracting its current control terminal voltage from its own current control voltage is equal to or less than a second reference value (negative value), The power supply system according to claim 9, wherein the voltage control information for correcting and reducing the voltage control information is output, and otherwise, the voltage control information is output so that the voltage target value of itself is maintained.   Each voltage target value setting unit, when a value obtained by subtracting its current control terminal voltage from its own current control voltage is equal to or greater than a first reference value (positive value), Output the voltage control information to the effect of correcting and increasing the voltage control information, and outputting the voltage control information to correct and decrease the voltage target value of the self when the second reference value (negative value) or less In other cases, the voltage control information is output so as to maintain the voltage target value of itself. The power supply system using a plurality of switching power supply devices according to claim 8, wherein the plurality of switching power supply devices are connected in parallel to each other at the output ends, and the current control terminals are connected to each other.
One of the plurality of units is a master power source, and the other is a slave power source. The master power source is set to a correction amount for correcting the voltage target value, and the slave power source sets the voltage target value. The correction amount when correcting is set to a value other than zero,
The voltage target value setting unit of each slave power supply observes its own current control terminal and detects its voltage, and the value obtained by subtracting its own current control terminal voltage from its own current control voltage is: When the voltage is equal to or greater than the first reference value (positive value), the voltage control information is output to increase the voltage target value of itself by the set correction amount, and the second reference value (negative value) ) In the following cases, the voltage control information indicating that the voltage target value is decreased by the set correction amount is output. In other cases, the voltage target value is maintained. The power supply system outputs the voltage control information as described above.

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