JP7068858B2 - Switching power supply - Google Patents

Description

The present invention relates to a switching power supply device.

Generally, a switching power supply device such as a DC / DC converter includes a current detecting means for detecting an output current. For example, Patent Document 1 describes a method in which a shunt resistor is provided as a current detecting means and an output current is detected based on a potential difference appearing at both ends of the shunt resistor. Further, Patent Document 2 describes a method in which a current transformer is provided as a current detecting means and an output current is detected from a current change detected by the current transformer.

Japanese Patent Application Laid-Open No. 2003-18827 Japanese Unexamined Patent Publication No. 2005-304116

However, when a shunt resistor is used as the current detecting means, power loss occurs due to the shunt resistor. Further, when a current transformer is used as the current detecting means, only alternating current can be detected, and direct current cannot be detected.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a switching power supply device that detects a direct current without causing a power loss.

One aspect of the present invention is an inductor whose one end is connected to a DC power supply, a switching element that turns on and off the input current value flowing from the DC power supply to the inductor, and smoothing connected between the other end of the inductor and ground. Subtracting the ripple current value from the capacitor, the first AC current sensor for measuring the input current value, the second AC current sensor for measuring the ripple current value flowing through the smoothing capacitor, and the input current value. It is a switching power supply device including a calculation unit for calculating a DC current value output from the smoothing capacitor.

One aspect of the present invention is the above-mentioned switching power supply device, wherein the switching element includes a first switching element and a second switching element connected in series with each other, and one end of the inductor is the first. The first alternating current sensor is connected between the switching element of the above and the second switching element, and the first alternating current sensor measures the first alternating current value flowing from the first switching element to one end of the inductor. A current sensor and a lower AC current sensor 11 for measuring a second AC current value flowing from the second switching element to one end of the inductor are provided, and the first AC current value and the second AC current value are provided. Further, an addition circuit for calculating the input current value by adding the AC current value is provided.

One aspect of the present invention is the switching power supply device described above, wherein the first AC current sensor and the second AC current sensor integrate output signals from the Rogowski coil and the Rogowski coil, respectively. It is equipped with an integrator circuit.

One aspect of the present invention is the switching power supply device described above, wherein the Rogoski coil is formed in an inner layer of a multilayer substrate.

As described above, according to the present invention, the direct current can be detected without causing a power loss.

It is a figure which shows an example of the schematic structure of the switching power supply device 1 which concerns on one Embodiment of this invention. It is a circuit diagram which shows an example of the integration circuit 102 which concerns on one Embodiment of this invention. It is a figure which shows the output waveform of the addition circuit 91 which concerns on one Embodiment of this invention. It is a figure which shows the output waveform of the subtraction circuit 92 which concerns on one Embodiment of this invention. It is a figure which shows the flow of operation of the switching power supply device 1 which concerns on one Embodiment of this invention.

Hereinafter, the switching power supply device according to the embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an example of a schematic configuration of a switching power supply device 1 according to an embodiment of the present invention. The switching power supply device 1 is, for example, a step-down switching regulator that steps down the voltage Vin output by the DC power supply 2 and supplies the output voltage Vo to the load unit R. The load unit R is a device or circuit to which the switching power supply device 1 is connected and the output voltage Vo of the switching power supply device 1 is supplied.

As shown in FIG. 1, the switching power supply device 1 includes a DC power supply 2, a switching element 31 (first switching element), a switching element 32 (second switching element), an inductor 4, a smoothing capacitor 5, and a first alternating current. It includes a current sensor 6, a second alternating current sensor 7, a control unit 8, and a calculation unit 9.

The DC power supply 2 is a supply source for supplying DC power such as a battery, and supplies DC power of voltage Vin between the power supply line L1 and the GND (ground) line L2.

The switching element 31 and the switching element 32 are, for example, n MOSFETs (n-type MOS field effect transistors), and are connected in series between the power supply line L1 and the GND line L2. In the present embodiment, the switching element 31 and the switching element 32 have the same configuration, and when indicating an arbitrary switching element included in the switching power supply device 1 or when not particularly distinguished, the switching element 3 is used. explain.

In the switching element 31, the source terminal is connected to the node N1, the drain terminal is connected to the power supply line L1, and the gate terminal is connected to the signal line of the control signal S1 output from the control unit 8. Here, the control signal S1 is a pulse signal that controls the switching element 31.
Further, in the switching element 32, the source terminal is connected to the GND line L2, the drain terminal is connected to the node N1, and the gate terminal is connected to the signal line of the control signal S2 output from the control unit 8. Here, the control signal S2 is a pulse signal that controls the switching element 32.

The inductor 4 is, for example, a coil for step-down, and one end thereof is connected between the switching element 31 and the switching element 32. Specifically, one end of the inductor 4 is connected to a connection point N1 between the source terminal of the switching element 31 and the drain terminal of the switching element 32. Further, the other end of the inductor 4 is connected to the output line L3 of the switching power supply device 1. Here, the other end of the inductor 4 and the other end of the smoothing capacitor 5 are connected to the output line L3.

The smoothing capacitor 5 is connected between the output line L3 and the GND line L2, and smoothes the output voltage Vo of the switching power supply device 1. One end of the smoothing capacitor 5 is connected to the other end of the inductor 4, and the other end is connected to the output line L3.

The first AC current sensor 6 measures the input current value Iin flowing from the DC power supply 2 to the inductor 4. This input current value Iin is an alternating current value because it is turned on and off by the switching element 3.

Specifically, the first AC current sensor 6 includes an upper AC current sensor 10 and a lower AC current sensor 11.

The upper AC current sensor 10 measures the first AC current I1 value flowing from the switching element 31 to one end of the inductor 4. The specific configuration of the upper AC current sensor 10 will be described below.

The upper alternating current sensor 10 includes a Rogoski coil 101 and an integrating circuit 102.

The Rogoski coil 101 measures the first alternating current I1 flowing through the switching element 31 connected to one end of the inductor 4. The Rogoski coil 101 is arranged, for example, on the connection line between the source terminal of the switching element 31 and the connection point N1, and detects the current flowing through the connection line. The Rogoski coil 101 is formed, for example, in the inner layer of the multilayer board in which the connection line between the source terminal of the switching element 31 and the connection point N1 is formed.

The integrator circuit 102 has a reset function and integrates the output signal output from the Rogoski coil 101. Here, a specific configuration of the integrating circuit 102 will be described with reference to FIG.

FIG. 2 is a circuit diagram showing an example of the integrating circuit 102 according to the embodiment of the present invention.
As shown in FIG. 2, the integrating circuit 102 includes a resistor 121, an operational amplifier 122, a capacitor 123, and a reset switch 124.

The resistor 121 is connected between one end of the Rogoski coil 101 and the inverting input terminal of the operational amplifier 122. Further, the capacitor 123 is connected between the inverting input terminal of the operational amplifier 122 and the output terminal of the operational amplifier 122.

The operational amplifier 122 functions as an integrator circuit by connecting the resistor 121 and the capacitor 123. In the operational amplifier 122, one end of the Rogoski coil 101 is connected to the inverting input terminal via a resistor 121, and the other end of the Rogoski coil 101 is connected to the non-inverting input. The operational amplifier 122 uses the output signal from the Rogoski coil 101 as an input signal (IN), and outputs an output signal (OUT) obtained by integrating the output of the Rogoski coil 101.

The reset switch 124 is connected in parallel with the capacitor 123 between the inverting input terminal of the operational amplifier 122 and the output terminal of the operational amplifier 122. The reset switch 124 is a switch that resets the output potential of the integrating circuit 102, and is controlled to be in a conductive state by a reset signal S3 (pulse signal) output by the control unit 8. The reset switch 124 is controlled to a conduction state (on state) when the integration circuit 102 is reset.

When the switching element 31 is controlled to be in the ON state by the control signal S1 output by the control unit 8, the integrating circuit 102 sends the first output signal showing the current waveform of the first AC current value I1 to the calculation unit 9. Output.

The lower AC current sensor 11 measures the second AC current value I2 flowing from the switching element 32 to one end of the inductor 4. The specific configuration of the lower AC current sensor 11 will be described below.

The lower alternating current sensor 11 includes a Rogoski coil 111 and an integrating circuit 112.

The Rogoski coil 111 detects a second alternating current value I2 flowing through the switching element 32 connected to one end of the inductor 4. The Rogoski coil 111 is arranged, for example, on the connection line between the drain terminal of the switching element 32 and the connection point N, and detects the current flowing through the connection line. The Rogoski coil 111 is formed, for example, in the inner layer of the multilayer board in which the connection line between the drain terminal of the switching element 32 and the connection point N is formed.

The integrator circuit 112 has a reset function and integrates an output signal output from the Rogoski coil 111. Since the configuration of the integrating circuit 112 is the same as the configuration of the integrating circuit 102, the description thereof will be omitted.

When the switching element 32 is controlled to be in the ON state by the control signal S2 output by the control unit 8, the integrating circuit 112 sends a second output signal indicating a current waveform of the second AC current value I2 to the calculation unit 9. Output.

The second AC current sensor 7 measures the ripple current value Ir flowing through the smoothing capacitor 5. The specific configuration of the second alternating current sensor 7 will be described below.

The second alternating current sensor 7 includes a Rogoski coil 71 and an integrator circuit 72.

The Rogoski coil 71 detects the ripple current value Ir flowing through the smoothing capacitor 5. The Rogoski coil 71 is arranged, for example, on the connection line between the connection point N2 between one end of the smoothing capacitor 5 and the other end of the inductor and the ground, and detects the current flowing through the connection line. The Rogoski coil 71 is formed, for example, in the inner layer of the multilayer board in which the connection line between the connection point N2 and the ground is formed.

The integrator circuit 72 may or may not have a reset function as shown in FIG. 2. The integrator circuit 72 obtains a current waveform having a ripple current value Ir by integrating the output signal output from the Rogoski coil 71. Then, the integrating circuit 72 outputs the current waveform of the ripple current value Ir as a third output signal to the calculation unit 9.

The control unit 8 is, for example, a processor including a CPU (Central Processing Unit) and the like, and performs various controls based on the output current value Io calculated by the calculation unit 9. Further, the control unit 8 controls the switching of the switching element 31 and the switching element 32, and also controls the reset function of the integrating circuits 102 and 112. For example, the control unit 8 controls the conduction state of the switching element 31 with the pulse signal by the control signal S1, and controls the continuity state of the switching element 32 with the pulse signal by the control signal S2. Further, the control unit 8 resets (initializes) the integrating circuits 102 and 112 by outputting a reset signal to the integrating circuits 102 and 112.

The calculation unit 9 calculates the output current value Io, which is a direct current output from the switching power supply device 1, by subtracting the ripple current value Ir from the input current value Iin. Hereinafter, a specific configuration of the arithmetic unit 9 according to the embodiment of the present invention will be described.

The calculation unit 9 includes an addition circuit 91, a subtraction circuit 92, an amplifier circuit 93, and an A / D conversion calculation processing unit 94.

The addition circuit 91 calculates the input current value Iin by adding the first AC current value I1 and the second AC current value I2. Specifically, as shown in FIG. 3, the addition circuit 91 acquires the current waveform W1 of the first AC current value I1 from the integration circuit 102. Further, the addition circuit 91 acquires the current waveform W2 of the second AC current value I2 from the integration circuit 112. Since the input current value Iin is composed of the first AC current value I1 and the second AC current value I2, the adder circuit 91 adds the current waveform W1 and the current waveform W2 to the input current value. The current waveform W3 of Iin is calculated. Acquiring the current waveform W3 of the input current value Iin is to acquire the value of the input current value Iin.

The subtraction circuit 92 calculates the output current value Io, which is a direct current output from the switching power supply device 1, by subtracting the ripple current value Ir from the input current value Iin calculated by the addition circuit 91. Specifically, as shown in FIG. 4, the subtraction circuit 92 acquires the current waveform W4 of the ripple current value Ir from the integration circuit 72. Further, the subtraction circuit 92 acquires the current waveform W3 of the input current value Iin from the addition circuit 91. Since the input current value Iin is composed of the output current value Io and the ripple current value Ir, the subtraction circuit 92 calculates the current waveform W5 of the output current value Io by subtracting the current waveform W4 from the current waveform W3. do. Acquiring the current waveform W5 of the output current value Io is to acquire the value of the output current value Io.

The amplifier circuit 93 amplifies the signal of the current waveform W5 having the output current value Io calculated by the subtraction circuit 92 at a predetermined amplification factor, and outputs the signal to the A / D conversion calculation processing unit 94.

The A / D conversion calculation processing unit 94 converts an analog signal, which is an output signal from the amplifier circuit 93, into a digital signal, and outputs the converted digital signal to the control unit 8, so that the digital value of the output current value Io is digital. Is given to the control unit 8.

Next, the operation flow of the switching power supply device 1 according to the embodiment of the present invention will be described. FIG. 5 is a diagram showing an operation flow of the switching power supply device 1 according to the embodiment of the present invention.

The upper AC current sensor 10 measures the first AC current value I1 flowing from the switching element 31 to one end of the inductor 4, and outputs the measurement result to the calculation unit 9 (step S101). The lower AC current sensor 11 measures the second AC current value I2 flowing from the switching element 32 to one end of the inductor 4, and outputs the measurement result to the calculation unit 9 (step S102).

The second AC current sensor 7 measures the ripple current value Ir flowing through the smoothing capacitor 5 and outputs the measurement result to the calculation unit 9 (step S103).

The calculation unit 9 adds the first AC current value I1 measured by the upper AC current sensor 10 and the second AC current value I2 measured by the second AC current sensor 7 to input current. The value Iin is calculated (step S104). Next, the calculation unit 9 subtracts the ripple current value Ir measured by the second AC current sensor 7 from the calculated input current value Iin to obtain the output current Io output from the switching power supply device 1. Calculate (step 105). Then, the calculation unit 9 converts the calculated output current value Io into a digital signal and outputs it to the control unit 8 (step S106).

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs and the like within a range that does not deviate from the gist of the present invention.

In the above embodiment, an example of the case where the switching power supply device 1 is a step-down type switching regulator has been described, but the present invention is not limited to this, and for example, a step-up type switching regulator or a DC / DC converter may be used. good.

Further, the above-mentioned arithmetic unit 9 may have a computer system inside. The processing process of the arithmetic unit 9 described above is stored in a computer-readable recording medium in the form of a program, and the processing is performed by the computer reading and executing this program. Here, the computer-readable recording medium refers to a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Further, the computer program may be distributed to the computer via a communication line, and the computer receiving the distribution may execute the program.

As described above, the switching power supply device 1 according to the embodiment of the present invention measures the first AC current sensor 6 for measuring the input current value Iin and the ripple current value Ir flowing through the smoothing capacitor 5. By subtracting the ripple current value Ir measured by the second AC current sensor 7 from the input current value Iin measured by the AC current sensor 7 of 2 and the first AC current sensor 6, the switching power supply device 1 can be used. A calculation unit 9 for calculating an output DC current value (output current value Io) is provided.

According to such a configuration, the direct current can be detected without using the shunt resistor. That is, the switching power supply device 1 can detect the output current value Io without causing a power loss.

Further, the arithmetic unit 9 uses a Rogowski coil to obtain a first alternating current value I1 flowing through the switching element 31 connected to one end of the inductor 4, and a second alternating current flowing from the switching element 32 to one end of the inductor 4. The input current value Iin is calculated by measuring the value I2 and adding the measured first alternating current value I1 and the second alternating current value I2.

According to such a configuration, the input current value Iin can be detected without using the shunt resistance. That is, the switching power supply device 1 can detect the input current value Iin without causing a power loss.

1 Switching power supply device 2 DC power supply 3 Switching element 4 inductor 5 Smoothing capacitor 6 First AC current sensor 7 Second AC current sensor 8 Control unit 9 Calculation unit 10 Upper AC current sensor 11 Lower AC current sensor 91 Addition Circuit 92 Subtraction circuit 93 Amplifier circuit 94 A / D conversion calculation processing unit 71, 101, 111 Logoski coil 72, 102, 112 Integrator circuit

Claims (3)

A switching element having a first switching element and a second switching element connected in series with each other and connected to a DC power supply ,
An inductor in which one end is connected between the first switching element and the second switching element,
A smoothing capacitor connected between the other end of the inductor and ground,
An upper AC current sensor that measures the first AC current value that flows from the first switching element to one end of the inductor, and a second AC current value that measures the second AC current value that flows from the second switching element to one end of the inductor. A first alternating current sensor with a lower alternating current sensor and
A second AC current sensor that measures the ripple current value flowing through the smoothing capacitor, and
An adder circuit that calculates the input current value flowing from the DC power supply to the inductor by adding the first AC current value and the second AC current value.
A calculation unit that calculates the DC current value output from the smoothing capacitor by subtracting the ripple current value from the input current value.
A switching power supply characterized by being equipped with. The first aspect of claim 1 is characterized in that the first alternating current sensor and the second alternating current sensor are provided with a Rogowski coil and an integrating circuit that integrates an output signal from the Rogowski coil, respectively. Switching power supply. The switching power supply device according to claim 2 , wherein the Rogoski coil is formed in an inner layer of a multilayer substrate.

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