JP4854556B2 - Power supply - Google Patents

Description

  The present invention relates to a power supply apparatus in which a control unit performs control to a power supply unit such as overcurrent protection and current sharing during parallel operation based on a detection signal obtained by a current detection unit.

  As a conventional power supply device of this type, for example, Patent Document 1 includes a current detection unit that detects a current flowing through a load, and whether a signal detected by the current detection unit is used as an input to determine whether or not an overcurrent state exists. A device having an overcurrent protection function for judging the above is known. In addition, during parallel operation in which output voltage is supplied to a common load from a plurality of power supply devices, the output current supplied from each power supply device to the load is detected by the current detection unit, and the output current between the power supply devices is detected. Control to compensate for imbalance is performed.

  FIG. 3 is a circuit configuration diagram illustrating an example of a switching power supply device including such a current detection unit. In the figure, reference numeral 1 denotes a DC power supply for supplying a DC input voltage Vi between input terminals 2A and 2B of the power supply device, and 3 denotes a load 5 between the input terminals 4A and 4B by converting the input voltage Vi into an output voltage Vo. It is a power supply part supplied to. Here, the load 5 is equivalently shown as a current source that generates a constant output current Io.

  The power supply unit 3 includes a transformer 7 that insulates the primary side from the secondary side, a switching element 8 made of, for example, a MOSFET, diodes 10 and 11 that form a rectifier circuit on the secondary side of the transformer 7, and two transformers 7. It has a forward-type circuit configuration including a choke coil 12 and a smoothing capacitor 13 that form a smoothing circuit on the next side. Specifically, a series circuit of the primary winding 7A of the transformer 7 and the switching element 8 is connected between the input terminals 2A and 2B, and by switching the switching element 8, the input voltage Vi from the DC power source 1 is obtained. Applied intermittently to the primary winding 7A. Accordingly, during the ON period of the switching element 8, a positive voltage is induced at the dot side terminal of the secondary winding 7B of the transformer 7 and the anode 10 is connected to the dot side terminal of the secondary winding 7B. Is conducted, and energy from the secondary winding 7B is sent to the smoothing capacitor 13 and the load 5 through the choke coil 12. In addition, during the OFF period of the switching element 8, another diode 11 having an anode connected to the non-dot side terminal of the secondary winding 7B conducts, and the energy stored in the choke coil 12 until then becomes the smoothing capacitor 13 And it is sent to the load 5.

  Reference numeral 21 denotes a current detector that detects an output current Io flowing through the load 5 from a current flowing through the secondary side of the transformer 7. The current detector 21 includes a resistor 22 as a current detector inserted and connected between the non-dot side terminal of the secondary winding 7B and the output voltage line of the output terminal 4B on the secondary side of the transformer 7, and the resistor 22 An amplifier 23 that amplifies a voltage Vis that is proportional to the output current Io generated between both ends of the signal and outputs it as a detection signal; a low-pass filter (LFP) 24 that removes a noise component included in the detection signal as a result of amplification; It is configured with.

  Reference numeral 31 denotes a digital signal processor (DSP) as a control unit that controls the operation of the power supply unit 3. The DSP 31 is provided on the secondary side of the transformer 7, and includes an A / D converter 32, a PWM (pulse width modulation) controller 33, a PWM signal generator 34, and a carrier wave generating means 35. ing. The A / D converter 32 is an input signal Vi generated between the input terminals 2A and 2B, both of which are analog signals, a detection signal of the current detection unit 21 from the LFP 24, and an output generated between the input terminals 4A and 4B. The voltage Vo is converted into a digital signal that can be processed inside the DSP 31. The PWM controller 33 is based on the deviation between the digital signal from the A / D converter 32 corresponding to the output voltage Vo and the reference voltage Vref, while taking into account fluctuations in the input voltage Vi and the detection signal of the current detector 21. The power supply unit 3 calculates an operation amount u for generating a desired output voltage Vo. The PWM signal generator 34 compares a manipulated variable u from the PWM controller 33 with a fixed-period sawtooth wave generated by the carrier wave generating means 35, and a drive signal having a pulse conduction width corresponding to the manipulated variable u. Is generated and supplied to the gate of the switching element 8.

  Since the DSP 31 is provided on the secondary side of the transformer 7, a signal is transmitted to each line connecting the input voltage line on the primary side of the transformer 7 and the gate of the switching element 8 and the DSP 31. Electrically insulated isolators 41 and 42 are inserted and connected, respectively.

In the DSP 31 having the above configuration, the input voltage Vi given to the power supply unit 3, the detection signal corresponding to the output current Io flowing through the load 5, and the output voltage Vo from the power supply unit 3 are respectively converted into A / D converters. 32 is converted into a digital signal, which is output to a PWM controller 33 which is a signal processing unit of the DSP 31. The PWM controller 33 calculates an operation amount u corresponding to the deviation between the detection level of the digital signal corresponding to the output voltage Vo and the reference voltage Vref at the steady time when the input voltage Vi and the output current Io do not change so much. Output to the PWM signal generator 34. On the other hand, when the input voltage Vi changes suddenly when the power supply unit 3 is started or stopped, or when the output current Io detected by the current detection unit 21 changes suddenly due to fluctuations in the load 5 or the like, the output voltage Vo The operation amount u is determined in consideration of these sudden changes in preference to the detection level. Based on the operation amount u thus determined, the PWM signal generator 34 supplies a drive signal having a desired pulse conduction width to the switching element 8 via the isolator 42, so that a stable output voltage Vo can be obtained in the load 5 at the steady state. When the input voltage Vi or the output current Io changes suddenly, the power supply unit 3 can be safely controlled.
JP 2006-129566 A

  The conventional power supply device shown in FIG. 3 has the following problems.

  In the power supply unit 3 that converts to the output voltage Vo lower than the input voltage Vi, a relatively large current value flows through the resistor 22 connected to the secondary side of the transformer 7, so that the loss as the power supply unit 3 is minimized. A resistor 22 having a small resistance value is used as a current detector. For this reason, the voltage Vis generated between both ends of the resistor 22 is small, and the amplifier 23 having a large amplification degree must be used, and the removal of noise components by the LPF 24 is essential. However, the LPF 24 itself causes a delay in the detection signal, which is a factor that hinders the speeding up of the control by the DSP 31.

  The present invention has been made paying attention to each of the above-mentioned problems, and its object is to provide a power supply device capable of realizing high-speed control by the control unit while preventing an increase in loss as a power supply unit. To do.

In order to achieve the above object, the present invention provides a choke coil that rectifies a voltage induced in a secondary winding of the transformer by intermittently applying an input voltage to the primary winding of the transformer by switching of a switching element. by smoothed by the smoothing circuit containing a power supply unit for supplying an output voltage to a load, a current detection unit for detecting a current flowing through the power supply unit, a detection signal and the output voltage from the current detector monitors And a control unit that determines a pulse conduction width of a drive signal supplied to the switching element and controls the power supply unit, wherein the current detection unit flows through a primary winding of the transformer A current detector that detects a primary current; and a sample hold unit that holds a signal peak value obtained by the current detector and outputs the signal peak value as the detection signal. Based on the serial output voltage and the drive signal to the switching element, comprising an average current estimator that estimates the average value of the ripple component of the current flowing through the choke coil, the average value obtained in this average current estimator, the The output current flowing through the load is estimated.

In this case, if the power supply unit is composed of a forward type converter, a half bridge type or a full bridge type converter, the average current estimator determines the switching determined by the output voltage and a drive signal to the switching element. It is preferable that the average value of the ripple of the current flowing through the choke coil is estimated based on the off time of the element.

Instead, when the power supply unit is composed of a forward type, half bridge type or full bridge type converter converter, the average current estimator is the switching determined by the output voltage and a driving signal to the switching element. The average value of the ripple of the current flowing through the choke coil may be estimated based on the ON time of the element and the input voltage.

  The sample hold unit is charged with a switching element that is turned on / off by the drive signal, and a voltage proportional to the primary current during an on period of the switching element, and a peak of the charging voltage during the off period of the switching element. And a capacitive element whose value is held as the signal peak value.

  The current detector is preferably a current transformer.

According to the first aspect of the present invention, the primary current flowing through the primary winding of the transformer is detected by the current detector, and the signal peak value obtained by the current detector is held by the sample and hold unit, while the average current is estimated. The device estimates the average value of the ripple of the current flowing through the choke coil based on the output voltage from the power supply unit and the drive signal to the switching element, and without using any existing amplifier or filter. Can be estimated. Therefore, by monitoring the fluctuations in the output current of the load, it becomes possible to control the power supply unit such as overcurrent protection and current sharing at high speed without delay. Further, if the output voltage is lower than the input voltage, the current flowing through the primary side of the transformer is smaller than the current flowing through the secondary side, and the loss as a current detector can be reduced.

According to the invention of claim 2, in the case of a power supply unit having a forward type converter, a half bridge type or a full bridge type converter, if the output voltage and the off time of the switching element are known, the input voltage or the like can be monitored, The average current estimator can estimate the average value of the ripple of the current flowing through the choke coil . Therefore, the configuration of the control unit can be simplified.

According to the invention of claim 3, in the case of a power supply unit having a forward converter, a half-bridge type or a full-bridge type converter, if the on-time of the switching element is known from the drive signal to the switching element, the input voltage and the output voltage Taking each information, the average current estimator can estimate the average value of the ripple of the current flowing through the choke coil .

  According to the fourth aspect of the present invention, in order to hold the peak value of the signal obtained by the current detector, the switch element that is turned on / off using the drive signal to the switching element, and the switching element is turned on , If there is a capacitor that charges and holds a voltage proportional to the primary current with the off operation, the peak value of the signal obtained by the current detector can be easily held. Therefore, in this case, the configuration as the current detection unit can be simplified.

  According to the invention of claim 5, the loss can be reduced as compared with other current detectors such as resistors. Further, in the configuration in which the control unit is provided on the secondary side of the transformer, the current transformer itself arranged on the primary side of the transformer also functions as an isolator, and the configuration as the current detection unit can be simplified.

  Hereinafter, a preferred embodiment of a power supply device according to the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the part which is common in FIG. 3 shown in the prior art example, and the description of the common part is abbreviate | omitted as much as possible to avoid duplication.

  FIG. 1 shows a circuit configuration of a power supply apparatus proposed in this embodiment. First, the difference between the power supply unit 3 and the conventional example will be described. Here, instead of the current detection unit 22, a current transformer 52 as a current detector, a backflow prevention diode 53, a resistor 54, and a capacitor 55 are used. And a switch element 56 made of a MOSFET, and a new current detector 51 is provided. The primary winding 52A of the current transformer 52 is connected in series with the primary winding 7A of the transformer 7 on the primary side of the transformer 7 instead of the secondary side of the transformer 7 as in the prior art. For example, a resistor or the like may be used as the current detector, but the current transformer 52 is most preferable in that the loss is small and an isolator is not required when supplying a signal to the DSP 31. Further, when the output voltage Vo is lower than the input voltage Vi, the current flowing on the primary side of the transformer 7 is smaller than that on the secondary side, and the loss as a current detector can be reduced.

  The current detection unit 51 connects a series circuit of a diode 53 and a resistor 54 between both ends of the secondary winding 52 </ b> B of the current transformer 52, and a capacitor 55 and a switch element forming a sample hold circuit between both ends of the resistor 54. The voltage Ves generated across the capacitor 55 is output to the A / D converter 32 as a detection signal of the current detection unit 51. Further, the pulse drive signal from the PWM generator 34 is given to the gate of the switch element 56, and the switch element 56 is turned on and off at the same timing as the switching element 8. As a result, the voltage Ves proportional to the peak value of the current iLf flowing through the choke coil 12 is held between both ends of the capacitor 55 during the OFF period of the switching element 8.

  As a modification of the power supply unit 3, a forward type circuit configuration is shown here, but the power supply unit 3 having a different circuit configuration such as a flyback type, push-pull type, half bridge type, full bridge type, etc. May be adopted. In this case, the primary winding 52A of the current transformer 52 detects, on the primary side of the transformer 7, the current iLf flowing through the choke coil 12 and thus the current flowing through the primary winding 7A of the transformer 7 even indirectly by the current detection unit 51. It is only necessary to be connected so that it can. Moreover, the power supply part 3 of an uninterruptible power supply including a backup power supply (not shown) can also be included. Other configurations of the power supply unit 3 are the same as those shown in FIG.

  Next, with respect to the DSP 31, changes to the conventional example will be described. The DSP 31 in this embodiment includes a ripple of the current iLf flowing through the choke coil 12 in addition to the A / D converter 32, the PWM controller 33, the PWM signal generator 34, and the carrier wave generating means 35 shown in the conventional example. An average current estimator 61 that estimates an average current value iLave with canceled components is provided.

  The A / D converter 32 converts the input voltage Vi applied to the power supply unit 3, the detection signal corresponding to the output current Io from the current detection unit 51, and the output voltage Vo from the power supply unit 3 into digital signals, respectively. These digital signals are output to the PWM controller 33. In particular, a digital signal corresponding to the output voltage Vo and, in some cases, a digital signal corresponding to the input voltage Vi are converted into an average current estimator described later. 61 is also output. Further, the average current estimator 61 uses the operation amount u calculated by the PWM controller 33 and the carrier wave generation means 35 in order to calculate the ON time or OFF time of the switching element 8 by the internal time calculation unit 62. Each information of the amplitude of the generated sawtooth wave is input. The time calculation unit 62 may be provided as an independent function outside the average current estimator 61 without being incorporated in the average current estimator 61.

The average current estimator 61 uses the digital signal supplied from the A / D converter 32 and the ripple of the current iLf flowing through the choke coil 12 based on the on time Ton or the off time Toff of the switching element 8 calculated by the time calculation unit 62. The average value iLave of the components is estimated. When the PWM controller 33 determines that the detection signal of the current detector 51 converted into a digital signal by the A / D converter 31 is held at a constant voltage level value, the value at this time and the average current estimated value 61 The output current Io of the load 5 is estimated based on the estimated average value iLave taken in from. The PWM controller 33 takes into account variations in the input voltage Vi and the estimated output current Io ′ of the load 5 based on the deviation between the digital signal from the A / D converter 32 and the reference voltage Vref according to the output voltage Vo. However, the operation amount u for the power supply unit 3 to generate the desired output voltage Vo is calculated.

  Next, the operation of each part in the above configuration will be described with reference to the waveform diagram of FIG. In the figure, the uppermost waveform is the voltage waveform of the drive signal output from the PWM signal generator 34. Hereinafter, the waveform of the current flowing through the primary winding 7A of the transformer 7 and the waveform of the voltage Ves across the capacitor 55 are shown. Respectively.

  When the drive signal from the PWM signal generator 34 is at the H (high) level, both the switching element 8 and the switching element 56 are turned on. At this time, in the power supply unit 3, the input voltage Vi from the DC power supply 1 is applied to the primary winding 7A of the transformer 7, and a positive voltage is induced at the dot side terminal of the secondary winding 7B of the transformer 7. As a result, the diode 10 becomes conductive, while the other diode 11 becomes non-conductive, and energy from the secondary winding 7B is sent to the smoothing capacitor 13 and the load 5 through the choke coil 12. At this time, a current from the primary winding 7A, which increases depending on the inductance L of the choke coil 12, flows through the primary winding 52A of the current transformer 52, and the current flowing through the primary winding 7A flows into the primary winding 52A of the current transformer 52. It is detected by the secondary winding 52B. As a result, the diode 53 becomes conductive and the switch element 56 is turned on, so that the capacitor 55 is charged by the current flowing through the secondary winding 52B, and the voltage Ves across the capacitor 55 causes the choke coil 12 to The current iLf that flows and thus rises similarly to the current that flows through the primary winding 7A.

  Here, when the power supply unit 3 has a forward converter configuration as shown in FIG. 1, the value of the ripple current ΔiL included in the current iLf flowing through the choke coil 12 during the ON period Ton of the switching element 8 is It is expressed by Equation 1.

  However, Np is the number of turns of the primary winding 7A of the transformer 7, and Ns is the number of turns of the secondary winding 7B of the transformer 7.

  Eventually, when the drive signal from the PWM signal generator 34 changes to the L (low) level, both the switching element 8 and the switch element 56 are turned off. Therefore, the application of the input voltage Vi to the primary winding 7A of the transformer 7 is interrupted, and the diode 10 on the secondary side of the transformer 7 becomes non-conductive while the diode 11 becomes conductive. Therefore, the power supply unit 3 is in a state where the primary side and the secondary side of the transformer 7 are separated, and the energy stored in the choke coil 12 until then is sent to the smoothing capacitor 13 and the load 5.

  At this time, because the switch element 56 is turned off, the voltage Ves between both ends of the capacitor 55 is held as it is at a value corresponding to the peak value of the current iLf flowing through the choke coil 12. The detection signal is output to the A / D converter 32. The A / D converter 32 takes in the input voltage Vi to the power supply unit 3 and the output voltage Vo from the power supply unit 3 in addition to the detection signal of the current detection unit 51, and outputs these digital signals to the PWM controller 33. Output to.

  Here, when the power supply unit 3 has the configuration of the forward converter as shown in FIG. 1, the value of the ripple current ΔiL included in the current iLf flowing through the choke coil 12 during the ON period Toff of the switching element 8 is It is expressed by Equation 2.

  The time calculation unit 62 built in the average current estimator 61 receives as input the operation amount u calculated by the PWM controller 33 and the amplitude of the sawtooth wave generated from the carrier wave generation means 35, and the switching element 8. Either the on-time Ton or the off-time Toff can be calculated. When the time calculation unit 62 calculates the ON time Ton of the switching element 8, the average current estimator 61 takes in the digital signal of the input voltage Vi and the digital signal of the output voltage Vo from the A / D converter 32, respectively. Based on the above equation 1, the value of the ripple current ΔiL is calculated. Note that the inductance L of the choke coil 12 and the number of turns Np and Ns are values that are known in advance, and therefore can be stored in the average current estimator 61. Further, when the time calculation unit 62 calculates the on-time Toff of the switching element 8, the average current estimator 61 can ripple based on the above equation 2 if the digital signal of the output voltage Vo is taken from the A / D converter 32. The value of the current ΔiL can be calculated. If the value of the ripple current ΔiL is halved, the average current estimator 61 can calculate the average current value iLave of the ripple current ΔiL (iLave = ΔiL / 2).

  On the other hand, when the PWM controller 33 determines that the detection signal of the current detection unit 51 converted into a digital signal by the A / D converter 31 is held at a constant voltage level value, the value at this time and the average current estimation Based on the estimated average value iLave taken from the value 61, the output current Io of the load 5 is estimated by averaging the current iLf flowing through the choke coil 12 by the output filter circuit (choke coil 12 and smoothing capacitor 13). The estimated output current Io ′ of the load 5 can be easily calculated by subtracting the estimated average value iLave from the current peak value ip corresponding to the peak value of the voltage Ves across the capacitor 55 (Io ′ = ip−iLave). .

  As described in the conventional example, the PWM controller 33 operates in accordance with the deviation between the detection level of the digital signal corresponding to the output voltage Vo and the reference voltage Vref at the steady time when the input voltage Vi and the output current Io do not change so much. The quantity u is calculated and output to the PWM signal generator 34. On the other hand, when the input voltage Vi changes suddenly when the power supply unit 3 is started or stopped, or when the output current Io detected by the current detection unit 21 changes suddenly due to fluctuations in the load 5 or the like, the output voltage Vo The operation amount u is determined in consideration of the detection level of the digital signal in accordance with the input voltage Vi and the estimated output current Io ′ of the load 5 in preference to the detection level of. Based on the operation amount u thus determined, the PWM signal generator 34 supplies a drive signal having a desired pulse conduction width to the switching element 8 via the isolator 42, so that a stable output voltage Vo can be obtained in the load 5 at the steady state. When the input voltage Vi or the output current Io changes suddenly, the power supply unit 3 can be safely controlled.

As described above, in the present embodiment as described above, by the switching of the switching elements 8, and intermittently applying an input voltage Vi to the primary winding 7A of a transformer 7 rectifies the voltage induced in the secondary winding 7B of transformer 7 By smoothing with the smoothing circuit including the choke coil 12, the power supply unit 3 that supplies the output voltage Vo to the load 5, the current detection unit 51 that detects the current flowing through the power supply unit 3, and the detection from the current detection unit 51 In the power supply apparatus including the DSP 31 as a control unit that monitors the signal and the output voltage Vo, determines the pulse conduction width of the drive signal supplied to the switching element 8, and controls the power supply unit 3. 51 holds a current detector (current transformer 52) for detecting a primary current flowing through the primary winding 7A of the transformer 7 and a peak value of a signal obtained by the current detector. Comprises a capacitor 55 and a switching element 56 as the sample-and-hold unit for outputting a detection signal of the detection unit 51, also DSP31 is, based on the drive signal to the output voltage Vo and the switching element 8, the current flowing through the choke coil 12 ILF The average current estimator 61 for estimating the average value iLave for the ripples of the current is estimated, and the estimated output current Io ′ flowing through the load 5 is estimated from the average value iLave obtained by the average current estimator 61. It is configured.

When such a configuration is adopted, the primary current flowing through the primary winding 7A of the transformer 7 is detected by the current detector, and the peak value of the signal obtained by this current detector is constituted by the capacitor 55 and the switch element 56. While being held by the sample hold unit, the average current estimator 61 is based on the output voltage Vo from the power supply unit 3 and the drive signal to the switching element 8, and the average value iLave for the ripple of the current iLf flowing through the choke coil 12. Is calculated and estimated, the output current Io ′ flowing through the load 5 can be estimated without using any existing amplifier 23 or filter (LFP 24). Therefore, by monitoring the estimated fluctuation of the output current Io ′ of the load 5, for example, control over the power supply unit 3 such as overcurrent protection and current sharing can be performed at high speed without delay. Further, if the power supply unit 3 is a step-down converter whose output voltage Vo is lower than the input voltage Vi, the current flowing through the primary side of the transformer 7 is smaller than the current flowing through the secondary side, resulting in a loss as a current detector. Can be reduced.

The power supply unit 3 is a forward converter that supplies power to the load 5 via the transformer 7 when the switching element 8 is on and supplies power to the load 5 on the secondary side of the transformer 7 when the switching element 8 is off. Is configured, the average current estimator 61 uses the output voltage Vo and the off time Toff of the switching element 8 determined by the drive signal to the switching element 8 as a ripple component of the current iLf flowing through the choke coil 12 . It is preferable that the average value iLave is estimated.

In this way, in the case of the power supply unit 3 having a forward type converter, if the output voltage Vo and the OFF time of the switching element 8 are known, the input voltage Vi or the like can be monitored as is apparent from the equation (1). The average current estimator 61 can naturally estimate the average value iLave for the ripple of the current iLf flowing through the choke coil 12 . Therefore, the control configuration of the DSP 31 as the control unit can be simplified.

Separately from this, when the power supply unit 3 is also composed of a forward type converter, the average current estimator 61 determines that the on-time Ton of the switching element 8 determined by the output voltage Vo and the drive signal to the switching element 8. Further, the average value iLave for the ripple of the current iLf flowing through the choke coil 12 may be estimated from the input voltage Vo. That is, if the on-time Ton of the switching element 8 is known from the drive signal to the switching element 8, each information of the input voltage Vi and the output voltage Vo is taken in, and the average current estimator 61 ripples the current iLf flowing through the choke coil 12. The average value iLave of minutes can be estimated. Such estimation of the average value iLave can be similarly applied to other half-bridge type or full-bridge type converters.

  Here, the sample hold unit is charged to a switch element 56 that is turned on / off by a drive signal to the switching element 8 and a voltage Ves proportional to the primary current of the transformer 7 during the ON period of the switch element 56. The capacitor 55 is provided as a capacitive element in which the peak value of the charging voltage Ves is held as the peak value of the signal from the current detection unit 51 during the off period of the element 56.

  Therefore, in order to hold the peak value of the signal obtained by the current transformer 52, the switch element 56 that is turned on / off using the drive signal to the switching element 8 and the on / off operation of the switch element 56 are used. Accordingly, if there is a capacitor 55 that charges and holds the voltage Ves proportional to the primary current of the transformer 7, the peak value of the signal obtained by the current transformer 52 can be easily held. Therefore, in this case, the configuration as the current detection unit 51 can be simplified.

  Further, as described above, it is preferable that the current detector constituting the current detection unit 51 be the current transformer 52, and loss can be reduced as compared with other current detectors such as resistors. In the configuration in which the DSP 31 is provided on the secondary side of the transformer 7, the current transformer 52 itself arranged on the primary side of the transformer also functions as an isolator, and the configuration as the current detection unit 51 can be simplified.

  In addition, this invention is not limited to the said Example, A various deformation | transformation implementation is possible in the range of the summary of this invention. The circuit configuration of the power supply device shown in FIG. 1 is merely an example, and it is needless to say that another circuit configuration that realizes an equivalent function may be adopted. For example, instead of the DSP 31, a control unit that performs arithmetic processing on analog signals as they are may be used.

It is a circuit block diagram of the power supply device in one Embodiment of this invention. FIG. 2 is an operation waveform diagram of each part in the circuit configuration of FIG. 1. It is a circuit block diagram of the power supply device in a prior art example.

3 Power supply unit 7 Transformer 7A Primary winding 7B Secondary winding 8 Switching element
12 Choke coil (smoothing circuit)
31 DSP (control unit)
51 Current detector 52 Current transformer (current detector)
55 Capacitor (sample hold unit, capacitive element)
56 Switch element (sample hold)
61 Average current estimator

Claims (5)

The switching of the switching element, by intermittently applying the input voltage to the primary winding of the transformer, is smoothed by the smoothing circuit including a choke coil to rectify the voltage induced in the secondary winding of the transformer, the load A power supply for supplying output voltage;
A current detection unit for detecting a current flowing through the power supply unit;
In the power supply device including a control unit that monitors the detection signal from the current detection unit and the output voltage, determines the pulse conduction width of the drive signal supplied to the switching element, and controls the power supply unit.
The current detection unit includes a current detector that detects a primary current flowing through the primary winding of the transformer, and a sample hold unit that holds a signal peak value obtained by the current detector and outputs the signal peak value as the detection signal. And
The control unit includes an average current estimator that estimates an average value of a ripple of a current flowing through the choke coil based on the output voltage and a drive signal to the switching element, and obtained by the average current estimator. A power supply apparatus characterized in that an output current flowing through the load is estimated from an average value. The power supply is composed of a forward type, half bridge type or full bridge type converter,
The average current estimator estimates an average value of a ripple of current flowing through the choke coil based on the output voltage and an off time of the switching element determined by a driving signal to the switching element. The power supply device according to claim 1. The power supply is composed of a forward type, half bridge type or full bridge type converter,
The average current estimator is an average value of a ripple of current flowing through the choke coil based on the output voltage, an ON time of the switching element determined by a driving signal to the switching element, and the input voltage. The power supply device according to claim 1, wherein the power supply device is estimated.   The sample hold unit is charged with a switching element that is turned on / off by the drive signal, and a voltage proportional to the primary current during an on period of the switching element, and a peak of the charging voltage during the off period of the switching element. The power supply device according to claim 1, further comprising: a capacitive element whose value is held as the signal peak value.   The power supply apparatus according to claim 1, wherein the current detector is a current transformer.

Images