Power supply

Abstract

To provide a power supply device which can easily speed up responsiveness of output voltage to control voltage.SOLUTION: A reference voltage output circuit 26 includes: an AD converter 18 which converts externally inputted control voltage Vco into a control voltage signal Sa; a digital signal processing unit 20 which generates a main voltage signal Sb corresponding to control voltage Vco on the basis of the control voltage signal Sa; a main voltage generation unit 22 which generates main voltage Vx corresponding to the main voltage signal Sb; a correction voltage generation unit 28 which generates correction voltage Vy proportional to an AC component of the control voltage Vco; and a reference voltage output unit 30 which corrects delay of a change of the main voltage Vx to the change of the control voltage Vco by combining the main voltage Vx with the correction voltage Vy and outputs the corrected voltage as reference voltage Vref. Output voltage Vo is controlled based on the reference voltage Vref.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power supply device capable of varying an output voltage setting value according to an externally input control voltage. [Background technology]

[0002] Conventionally, there has been a power supply device 10 as shown in Fig. 7(a), for example. The power supply device 10 includes a power conversion circuit 12 (e.g., a switching converter) that converts an input voltage Vi into a predetermined output voltage Vo and outputs the converted output voltage Vo, a reference voltage output circuit 14 that outputs a reference voltage Vref that is an analog voltage, and a control circuit 16 that controls the operation of the power conversion circuit 12 so that a detection voltage Vo1 that detects the output voltage Vo approaches the reference voltage Vref.

[0003] The control circuit 16 is composed of a Vo detection circuit 16a that outputs a detection voltage Vo1 by, for example, resistively dividing the output voltage Vo, and a Vs signal generation circuit 16b that receives the detection voltage Vo and a reference voltage Vref and outputs a control signal Vs (for example, a drive pulse that turns on and off a switching element) to the power conversion circuit 12 so that the detection voltage Vo1 approaches the reference voltage Vref. Therefore, the output voltage Vo is controlled to a value proportional to the reference voltage Vref.

[0004] 7(b), the reference voltage output circuit 14 is composed of an AD converter 18 that converts the control voltage Vco, which is an externally input analog voltage, into a control voltage signal Sa, which is a digital signal, a digital signal processing unit 20 that generates a reference voltage signal Sb, which is a digital signal corresponding to the control voltage Vco, based on the control voltage signal Sa, and a reference voltage generating unit 22 that generates a reference voltage Vref, which is an analog voltage corresponding to the reference voltage signal Sb. The reference voltage generating unit 22 is composed of, for example, a pulse width modulation unit that outputs a square wave voltage whose duty is set based on the reference voltage signal Sb, and a low-pass filter that smoothes the square wave voltage to generate a reference voltage.

[0005] The reference voltage Verf output by the reference voltage output circuit 14 is proportional to the externally input control voltage Vco (the proportionality coefficient may be 1). Therefore, by changing the control voltage Vco, the output voltage Vo can be varied to a desired value.

[0006] The digital signal processor 20 has a function of converting the externally input control voltage Vco into a digital control voltage signal Sa, as well as a function of generating a signal Sa with various properties according to user needs. Although a detailed explanation is omitted, by providing the digital signal processor 20 inside the reference voltage output circuit 14, the intelligence of the control of the power conversion circuit 12 can be significantly improved, and a multifunctional and high-performance power supply device 10 can be realized.

[0007] The configuration of the power supply device 10 is disclosed, for example, in Patent Document 1 by the present applicant. In the case of the switching power supply device described in Patent Document 1 (FIG. 1), the output control section 12 and the control reference voltage generating section 28 correspond to the reference voltage output circuit 14 of the power supply device 10, and the power converter 10 corresponds to the power conversion circuit 12 and the control circuit 16 of the power supply device 10. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2018-42383 A Summary of the Invention [Problem to be solved by the invention]

[0009] As shown in FIG. 8, the conventional power supply device 10 has a problem in that when the control voltage Vco is changed, there is a long delay time Tx until the reference voltage Vref changes to a voltage corresponding to the control voltage Vco.

[0010] 8 shows the operation of the power supply device 10 equipped with the reference voltage output circuit 14. In the initial state, the control voltage Vco is zero volts, so the reference voltage Vref is zero volts and the output voltage Vo is controlled to zero volts.

[0011] When the control voltage Vo is changed to a value higher than zero volts in order to raise the output voltage Vo to a predetermined value, the reference voltage generating unit 22 starts to raise the reference voltage Vref when the processing time Tx1 of the AD converter 18 and the digital signal processing unit 20 has elapsed, and when a further time Tx2 has elapsed, the reference voltage Vref reaches a value corresponding to the control voltage Vco and is maintained at that value. Therefore, the output voltage Vo can finally change to a voltage corresponding to the control voltage Vco after the delay time Tx=Tx1+Tx2 has elapsed.

[0012] The time Tx1 can be shortened by configuring the AD converter 18 and the digital signal processing unit 20 with a digital processor capable of high-speed operation, but this would result in a large increase in costs. Also, the time Tx2 can be shortened by changing the reference voltage generating unit 22 from a "pulse width modulation unit and low-pass filter" to a "DA converter", but then the advantage of using a "pulse width modulation unit and low-pass filter", that is, the advantage of being able to increase the resolution of the reference voltage Vref, would be lost.

[0013] As described above, it is not easy to shorten the delay time Tx, and increasing the speed of response of the output voltage Vo to the control voltage Vco has been a major challenge.

[0014] The present invention has been made in view of the above-mentioned background art, and has an object to provide a power supply device that can easily speed up the response of the output voltage to an externally input control voltage. [Means for solving the problem]

[0015] The present invention includes a power conversion circuit that converts an input voltage into a predetermined output voltage and outputs the converted output voltage, a reference voltage output circuit that outputs a reference voltage which is an analog voltage, and a control circuit that controls the operation of the power conversion circuit so that a detection voltage obtained by detecting the output voltage approaches the reference voltage, The reference voltage output circuit includes: To control the output voltage an AD converter that converts an externally input control voltage, which is an analog voltage, into a control voltage signal, which is a digital signal; a digital signal processing unit that generates a main voltage signal, which is a digital signal corresponding to the control voltage, based on the control voltage signal; a main voltage generating unit that generates a main voltage, which is an analog voltage corresponding to the main voltage signal; When the control voltage changes a correction voltage generating unit that generates a correction voltage that is an analog voltage proportional to an AC component, and control and a reference voltage output section that corrects a delay in a change in the main voltage relative to a change in the voltage, and outputs the corrected voltage as the reference voltage.

[0016] The main voltage generation unit is composed of a pulse width modulation unit that outputs a rectangular wave voltage whose duty is set based on the main voltage signal, and a low pass filter that smoothes the rectangular wave voltage to generate the main voltage, and the low pass filter is composed of an output resistor having one end connected to the output end of the pulse width modulation unit, and a capacitor circuit that is a series circuit of two capacitors, with both ends of the series circuit connected between the other end of the output resistor and ground, and the correction voltage generation unit and the reference voltage output unit are preferably configured to be shared by the low pass filter, and be provided by connecting the midpoint of the series connection of the two capacitors to the input end of the AD converter, and the reference voltage is generated at the connection point between the output resistor and the capacitor circuit.

[0017] Alternatively, it is preferable that the main voltage generating unit is a DA converter, and the correction voltage generating unit and the reference voltage output unit are composed of an output resistor having one end connected to the output terminal of the DA converter, and a capacitor connected between the input terminal of the AD converter and the other end of the output resistor, and the reference voltage is generated at the connection point between the output resistor and the capacitor.

[0018] Alternatively, it is preferable that the main voltage generating unit is a DA converter, and the correction voltage generating unit and the reference voltage output unit are composed of an output resistor having one end connected to the output terminal of the DA converter, and a capacitor circuit which is a series circuit of two capacitors, with both ends of the series circuit connected between the other end of the output resistor and ground and the midpoint of the series circuit connected to the input terminal of the AD converter, and the reference voltage is generated at the connection point between the output resistor and the capacitor circuit. Effect of the Invention

[0019] In the power supply device of the present invention, the delay time until the reference voltage changes to a voltage corresponding to the control voltage when the control voltage is changed is significantly reduced by the operation of a unique correction voltage generation section and reference voltage output section provided in the reference voltage output circuit. This makes it easy to achieve high speed response of the output voltage to the control voltage, resulting in an inexpensive, high performance power supply device. [Brief description of the drawings]

[0020] [Figure 1] 1A is a block diagram showing the configuration of an embodiment of a power supply device of the present invention, and FIG. 1B is a block diagram showing the internal configuration of a reference voltage output circuit. [Diagram 2] FIG. 2 is a diagram illustrating a first specific example of the reference voltage output circuit shown in FIG. [Diagram 3] 3 shows operational waveforms of each part of the power supply device of this embodiment when the reference voltage output circuit shown in FIG. 2 is mounted thereon. [Figure 4] FIG. 2 is a diagram illustrating a second specific example of the reference voltage output circuit shown in FIG. [Diagram 5] 5 shows operational waveforms of each part of the power supply device of this embodiment when the reference voltage output circuit shown in FIG. 4 is mounted thereon. [Figure 6] FIG. 1C is a diagram illustrating a third specific example of the reference voltage output circuit shown in FIG. [Figure 7] FIG. 1A is a block diagram showing the configuration of a conventional power supply device, and FIG. 1B is a block diagram showing the internal configuration of a reference voltage output circuit. [Figure 8] 4 shows operational waveforms of various parts of a conventional power supply device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] An embodiment of the power supply device of the present invention will be described below with reference to Figs. 1 to 6. Here, the same components as those of the conventional power supply device 10 will be described with the same reference numerals. A power supply device 24 of this embodiment includes a power conversion circuit 12 (e.g., a switching converter) that converts an input voltage Vi to a predetermined output voltage Vo and outputs the converted output voltage Vo, a reference voltage output circuit 26 that outputs a reference voltage Vref that is an analog voltage, and a control circuit 16 that controls the operation of the power conversion circuit 12 so that a detection voltage Vo1 that detects the output voltage Vo approaches the reference voltage Vref. The difference from the power supply device 10 is that a new reference voltage output circuit 26 is provided instead of the reference voltage output circuit 14.

[0022] As shown in FIG. 1(a), the reference voltage output circuit 26 includes: To control the output voltage Vo The input circuit includes an AD converter 18 that converts a control voltage Vco, which is an externally input analog voltage, into a control voltage signal Sa, which is a digital signal, a digital signal processing unit 20 that generates a main voltage signal Sb, which is a digital signal corresponding to the control voltage Vco, based on the control voltage signal Sa, and a main voltage generating unit 22 that generates a main voltage Vx, which is an analog voltage corresponding to the main voltage signal Sb.

[0023] The main voltage signal Sb output by the digital signal processing unit 20 is the same as the reference voltage signal Sb in the conventional power supply device 10, but the name has been changed for ease of explanation. The main voltage generating unit 22 is the same block as the reference voltage generating unit 22 in the conventional power supply device 10, but the name has been changed for ease of explanation. The main voltage Vx output by the main voltage generating unit 22 is the same voltage as the reference voltage Vref in the conventional power supply device 10, but the name has been changed for ease of explanation.

[0024] The reference voltage output circuit 26 is characterized in that, in addition to the above blocks, it is provided with a unique correction voltage generating section 28 and a reference voltage output section 30. The correction voltage generating section 28 generates a control voltage Vco When the control voltage Vco changes The reference voltage output unit 30 generates a correction voltage Vy, which is an analog voltage proportional to the AC component (the proportionality coefficient may be 1). The reference voltage output unit 30 combines the correction voltage Vy with the main voltage Vx, thereby: control The reference voltage output circuit 26 corrects the delay in the change in the main voltage Vx relative to the change in the voltage Vco, and outputs the corrected voltage as the reference voltage Vref. First to third specific examples of the reference voltage output circuit 26 will be described below in order.

[0025] <First Specific Example of Reference Voltage Output Circuit 26> 2 shows the configuration of a reference voltage output circuit 26(1) which is a first specific example of the reference voltage output circuit 26. Since the AD converter 18 and the digital signal processing unit 20 therein are as described above, their explanation will be omitted.

[0026] The main voltage generating unit 22(1) is composed of a pulse width modulation unit 32 that outputs a square wave voltage Vp (peak value V1) in which a duty D is set based on a main voltage signal Sb, and a low pass filter 34 that smoothes the square wave voltage Vp to generate a main voltage Vx=D·V1. The low pass filter 34 is composed of an output resistor 36, one end of which is connected to the output end of the pulse width modulation unit 32, and a capacitor circuit 38, which is a series circuit of two capacitors 38a, 38b, with both ends of the series circuit connected between the other end of the output resistor 36 and ground.

[0027] The correction voltage generating unit 28(1) and the reference voltage output unit 30(1) are both formed by a low-pass filter 34, and are provided by connecting the midpoint of two series connected capacitors 38a, 38b to the input terminal of the AD converter, and a reference voltage Vref is generated at the connection point between the output resistor 36 and the capacitor circuit 38.

[0028] 3 shows the operating waveforms of each part of the power supply device 24 when the reference voltage output circuit 26(1) is installed. In the initial state, the control voltage Vco is zero volts, so the reference voltage Vref is zero volts and the output voltage Vo is controlled to zero volts.

[0029] When the control voltage Vo is changed to a value higher than zero volts in order to raise the output voltage Vo to a predetermined value, after the processing time Tx1 of the AD converter 18 and the digital signal processor 20 has elapsed, the main voltage generation unit 22(2) begins the operation of raising the main voltage Vx, and after a further time Tx2 has elapsed, the main voltage Vx reaches a value corresponding to the control voltage Vco (Vx=D·V1) and is maintained at that value.

[0030] In parallel with this, the correction voltage generating unit 28(1) adjusts the control voltage Vco The change is A correction voltage Vy proportional to the AC component is generated, and the reference voltage output unit 30(1) combines the correction voltage Vy with the main voltage Vx. control The delay in the change in the main voltage Vx relative to the change in the voltage Vco is corrected (the hatched portion in the Vref waveform in FIG. 3), and a reference voltage Vref with a waveform nearly similar to that of the control voltage Vco is generated at the connection point between the output resistor 36 and the capacitor circuit 38. Therefore, the output voltage Vo can quickly change to a value corresponding to the control voltage Vco without being affected by the delay time Tx=Tx1+Tx2.

[0031] Although not shown in FIG. 3, a similar operation occurs when the control voltage Vco is changed from a predetermined value to a lower value, and the output voltage Vo can quickly change to a value corresponding to the control voltage Vco without being affected by the delay time Tx=Tx1+Tx2.

[0032] The correction operation (shape of the hatched portion in the Vref waveform in FIG. 3) performed by the correction voltage generating unit 28(1) and the reference voltage output unit 30(1) can be adjusted as appropriate by changing the values ​​of the output resistor 36 and the capacitors 38a, 38b. In general, it is preferable to adjust the correction operation so that the Vref waveform is approximately similar to the Vcon waveform. In addition, in order to prevent overshoot and ringing from occurring when the output voltage Vo changes, it is also possible to adjust the slope of the change in the Vref waveform to be slightly gentler than the slope of the change in the Vco waveform.

[0033] <Second Specific Example of Reference Voltage Output Circuit 26> 4 shows the configuration of a reference voltage output circuit 26(2) which is a second specific example of the reference voltage output circuit 26. Since the AD converter 18 and the digital signal processing unit 20 therein are as described above, their explanation will be omitted.

[0034] The main voltage generating unit 22(2) is composed of a DA converter. The correction voltage generating unit 28(2) and the reference voltage output unit 30(2) are composed of an output resistor 40, one end of which is connected to the output end of the main voltage generating unit 22(2), and a capacitor 42, which is connected between the input end of the AD converter 18 and the other end of the output resistor 40. A reference voltage Vref is generated at the connection point between the output resistor 40 and the capacitor 42.

[0035] 5 shows the operating waveforms of each part of the power supply device 24 when the reference voltage output circuit 26(2) is installed. In the initial state, the control voltage Vco is zero volts, so the reference voltage Vref is zero volts and the output voltage Vo is controlled to zero volts.

[0036] When the control voltage Vo is changed to a value higher than zero volts in order to raise the output voltage Vo to a predetermined value, the main voltage generating unit 22(2) starts the operation of raising the main voltage Vx after the processing time Tx1 of the AD converter 18 and the digital signal processing unit 20 has elapsed. Because the main voltage generating unit 22(2) is a DA converter, the time Tx2 is short enough to be ignored, and when the time Tx≈Tx1 has elapsed, the main voltage Vx reaches a value corresponding to the control voltage Vco and is maintained at that value.

[0037] In parallel with this, the correction voltage generating unit 28(2) adjusts the control voltage Vco The change is A correction voltage Vy proportional to the AC component is generated, and the reference voltage output unit 30(1) combines the correction voltage Vy with the main voltage Vx. control The delay in the change in the main voltage Vx relative to the change in the voltage Vco is corrected (the hatched portion in the Vref waveform in FIG. 3), and a reference voltage Vref with a waveform nearly similar to that of the control voltage Vco is generated at the connection point between the output resistor 40 and the capacitor circuit 42. Therefore, the output voltage Vo can quickly change to a value corresponding to the control voltage Vco without being affected by the delay time Tx≈Tx1.

[0038] Although not shown in FIG. 5, a similar operation occurs when the control voltage Vco is changed from a predetermined value to a lower value, and the output voltage Vo can quickly change to a value corresponding to the control voltage Vco without being affected by the delay time Tx≈Tx1.

[0039] The correction operation (shape of the hatched portion in the Vref waveform in FIG. 5) performed by the correction voltage generating unit 28(2) and the reference voltage output unit 30(2) can be adjusted by changing the values ​​of the output resistor 40 and the capacitor 42. In general, it is preferable to adjust the correction operation so that the Vref waveform is approximately similar to the Vcon waveform. In addition, in order to prevent overshoot and ringing from occurring when the output voltage Vo changes, it is also possible to adjust the slope of the change in the Vref waveform so that it is slightly gentler than the slope of the change in the Vco waveform.

[0040] <Third Specific Example of Reference Voltage Output Circuit 26> 6 shows the configuration of a reference voltage output circuit 26(3) which is a third specific example of the reference voltage output circuit 26. Since the AD converter 18 and the digital signal processing unit 20 therein are as described above, their explanation will be omitted.

[0041] The main voltage generating unit 22(3) is composed of a DA converter, similar to the main voltage generating unit 22(2). The correction voltage generating unit 28(3) and the reference voltage output unit 30(3) are composed of an output resistor 44 having one end connected to the output end of the main voltage generating unit 22(3), and a capacitor circuit 46 which is a series circuit of two capacitors 46a, 46b, with both ends of the series connected between the other end of the output resistor 44 and the ground and with the midpoint of the series connected to the input end of the AD converter 18. A reference voltage Vref is generated at the connection point between the output resistor 44 and the capacitor circuit 46.

[0042] The operating waveforms of each part of the power supply device 24 equipped with the reference voltage output circuit 26(3) are almost the same as those shown in Fig. 5. In addition, the correction operations performed by the correction voltage generating unit 28(2) and the reference voltage output unit 30(2) (the shape of the hatched portion in the Vref waveform in Fig. 5) can also be adjusted by changing the values ​​of the output resistor 44 and the capacitors 46a and 46b.

[0043] The reference voltage output circuit 26(3) is characterized in that it can apply the dithering technique described in Japanese Patent No. 6368696 filed by the applicant of the present application. By applying this dithering technique, it is possible to improve the resolution of the main voltage Vx (≒ the resolution of the reference voltage Vref) that can be output by the main voltage generating unit 22(3), which is a DA converter, and therefore it is possible to control the output voltage Vo with high precision without using an expensive high-speed digital processor. The above-mentioned reference voltage output circuit 26(2) is characterized in that it has fewer parts than the reference voltage output circuit 26(3), but the above-mentioned dithering technique cannot be applied.

[0044] As described above, in the power supply device 24, the unique correction voltage generating unit 28 and reference voltage output unit 30 provided in the reference voltage output circuit 26 operate to significantly reduce the delay time until the reference voltage Vref changes to a voltage corresponding to the control voltage Vco when the control voltage Vco is changed. This makes it easy to speed up the responsiveness of the output voltage Vo to the control voltage Vco, thereby providing an inexpensive, high-performance power supply device.

[0045] The power supply device of the present invention is not limited to the above-mentioned embodiment and specific example. For example, the above-mentioned reference voltage output circuits 26(1), 26(2), and 26(3) are configured with the correction voltage generating section 28 and the reference voltage output section 30 in a composite manner to reduce the number of parts, but the correction voltage generating section and the reference voltage output section may be configured separately as long as the operation aimed at by the present invention is possible.

[0046] In addition, the circuit type of the power conversion circuit is not particularly limited, and may be a switching type or a dropper type. The present invention is a highly versatile technology and can be applied to various types of power conversion circuits to obtain the same effects. [Explanation of symbols]

[0047] 10,24 Power supply 12 Power Conversion Circuit 16 Control circuit 18 A / D converter 20 Digital signal processing section 22(22(1)~22(3)) Main voltage generator 26(26(1)~26(3)) Reference voltage output circuit 28(28(1)~28(3) Correction voltage generator 30(30(1)~30(3) Reference voltage output section 32 Pulse width modulation section 34 Low-pass filter 36,40,44 Output resistance 38, 46 Capacitor circuit 38a, 38b, 42, 46a, 46b Capacitors D Duty Sa control voltage signal Sb Main voltage signal Vco control voltage Vi input voltage Vo output voltage Vo1 detection voltage Vp Square wave voltage Vref Reference voltage Vs Control signal Vx Main voltage Vy compensation voltage

Claims

1. a power conversion circuit that converts an input voltage into a predetermined output voltage and outputs the converted output voltage; a reference voltage output circuit that outputs a reference voltage which is an analog voltage; and a control circuit that controls an operation of the power conversion circuit so that a detection voltage obtained by detecting the output voltage approaches the reference voltage; the reference voltage output circuit comprising: an AD converter that converts a control voltage, which is an analog voltage input from outside for controlling the output voltage, into a control voltage signal, which is a digital signal; a digital signal processing unit that generates a main voltage signal, which is a digital signal corresponding to the control voltage, based on the control voltage signal; a main voltage generation unit that generates a main voltage, which is an analog voltage corresponding to the main voltage signal; a correction voltage generation unit that generates a correction voltage, which is an analog voltage proportional to the AC component of the control voltage when the control voltage changes; and a reference voltage output unit that combines the correction voltage with the main voltage to correct a delay in change of the main voltage relative to a change in the control voltage, and outputs the corrected voltage as the reference voltage.

2. the main voltage generating section is composed of a pulse width modulation section which outputs a rectangular wave voltage whose duty is set based on the main voltage signal, and a low pass filter which smoothes the rectangular wave voltage to generate the main voltage, the low pass filter being composed of an output resistor having one end connected to an output end of the pulse width modulation section, and a capacitor circuit which is a series circuit of two capacitors, the two ends of which are connected between the other end of the output resistor and ground, 2. The power supply device according to claim 1, wherein the correction voltage generating unit and the reference voltage output unit are both formed by the low-pass filter, and the midpoint of the series connection of the two capacitors is connected to the input end of the AD converter, and the reference voltage is generated at the connection point between the output resistor and the capacitor circuit.

3. the main voltage generating unit is a DA converter, 2. The power supply device of claim 1, wherein the correction voltage generating unit and the reference voltage output unit are composed of an output resistor having one end connected to the output terminal of the DA converter and a capacitor connected between the input terminal of the AD converter and the other end of the output resistor, and the reference voltage is generated at the connection point between the output resistor and the capacitor.

4. the main voltage generating unit is a DA converter, 2. The power supply device of claim 1, wherein the correction voltage generating unit and the reference voltage output unit are configured with an output resistor having one end connected to the output terminal of the DA converter, and a capacitor circuit which is a series circuit of two capacitors, with both ends of the series connected between the other end of the output resistor and ground and with the midpoint of the series connected to the input terminal of the AD converter, and the reference voltage is generated at the connection point between the output resistor and the capacitor circuit.

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