Power supply control device

Abstract

If the input voltage changes due to switching of an AC power source, the time when the inductor current becomes zero and the element voltage of the switching element becomes a minimum value changes, resulting in an increase in switching loss. The present invention provides a power supply control device, comprising: a switch control unit that controls the on / off of the switching element of a step-up chopper; a detection unit that detects that a first value becomes smaller than a threshold value, the first value being a value based on the inductor voltage of the inductor of the step-up chopper; and a delay adjustment unit that adjusts the delay time from when the detection unit detects that the first value becomes smaller than the threshold value to when the switch control unit turns on the switching element, based on a second value based on the inductor voltage.

Description

Technical Field

[0001] The invention relates to a power supply control device. Background Art

[0002] Conventionally, in a boost chopper that boosts an AC voltage rectified by a full-wave rectifier circuit, the time from a specific reference moment to the moment when the inductor current becomes zero and the element voltage of the switching element becomes a minimum value is set in advance as a delay time, and the switching element is turned on after the delay time has passed from the reference moment, thereby reducing switching losses (for example, refer to Patent Documents 1 and 2).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2014-82924

[0004] Patent Document 2: Japanese Patent Application Publication No. 2017-225260 Summary of the invention

[0005] Technical issues

[0006] However, when the input voltage changes due to switching of the AC power supply or the like, the timing at which the element voltage of the switching element reaches a minimum value changes, resulting in an increase in switching loss.

[0007] Technical Solution

[0008] In order to solve the above-mentioned problems, in a first aspect of the present invention, a power supply control device is provided. The power supply control device may include a switch control unit that controls the on and off of the switch element of the step-up chopper. The power supply control device may include a detection unit that detects that a first value of an inductance voltage based on an inductor of the step-up chopper becomes less than a threshold value. The power supply control device may include a delay adjustment unit that adjusts the delay time from when the detection unit detects that the first value becomes less than the threshold value to when the switch control unit turns on the switch element, based on a second value based on the inductance voltage.

[0009] The delay adjustment unit may determine whether the second value is equal to or greater than a reference value during the on-period of the switch element. If it is determined that the second value is equal to or greater than the reference value, the delay adjustment unit may shorten the delay time to be shorter than the delay time when the second value is not equal to or greater than the reference value.

[0010] The switch control unit may turn on the switch element in response to the first value changing from above the threshold to below the threshold a predetermined number of times. The delay adjustment unit may adjust the delay time from when the first value changes from above the threshold to below the threshold a predetermined number of times to when the switch control unit turns on the switch element.

[0011] The switch control unit may include an on-timer unit that turns on the switch element after a predetermined on-timer time. The delay adjustment unit may further adjust the on-timer time based on the second value.

[0012] The step-up chopper may include a step-up transformer including an auxiliary winding and a main winding functioning as an inductor. The detection unit may use the auxiliary winding voltage as the first value.

[0013] The step-up chopper may include a transformer having an auxiliary winding and a main winding functioning as an inductor. The delay adjustment unit may use a current corresponding to a voltage of the auxiliary winding as the second value.

[0014] The delay adjustment unit may switch which of the delay time setting values ​​corresponding to each of the plurality of rated voltages is used as the delay time based on the second value in the on-period of the switching element.

[0015] The delay adjustment unit may adjust the delay time according to a change in the second value in accordance with a change in an AC input voltage from a power source that supplies electric power to the step-up chopper.

[0016] The delay adjustment unit may adjust the delay time according to a second value based on the inductor voltage during the off period of the switching element.

[0017] It should be noted that the above-mentioned summary of the invention does not list all the essential features of the present invention. In addition, sub-combinations of these feature groups can also constitute other inventions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A power supply device 1 according to this embodiment is shown.

[0019] Figure 2 The auxiliary winding voltage V ZCD waveform.

[0020] Figure 3 The inductor current I L1 , the source-drain voltage Vds of the switching element Q1, the auxiliary winding voltage V ZCD And the output signal QQ of RS type flip-flop 655.

[0021] Figure 4 The source-drain voltage Vds of the switching element Q1 when the AC input voltage is switched is shown.

[0022] Figure 5 The delay adjustment section 64 is shown.

[0023] Figure 6 The conduction timing unit 9 is shown.

[0024] Figure 7 The operation of a part of the power supply control device 6 is shown.

[0025] Figure 8 An input voltage identification unit 7A according to a modified example is shown.

[0026] Fig. 9 An input voltage identification unit 7B according to another modified example is shown.

[0027] Explanation of symbols

[0028] 1…power supply device, 2…AC power supply, 3…full-wave rectifier circuit, 4…boost chopper, 5…voltage error detection compensation circuit, 6…power supply control device, 7…input voltage identification unit, 7A…input voltage identification unit, 7B…input voltage identification unit, 8…delay circuit, 9…on timing unit, 50…RC phase compensation circuit, C50…capacitor, R50…resistor, C51…capacitor, 61…comparison voltage generation unit, 61a…error amplifier, 62…positive voltage clamp circuit, 62a…zener diode, 63…detection unit, 64…delay adjustment unit, 65…switch control unit, 70…current mirror circuit, 71…bipolar transistor, 72…resistor, 73…comparator, 74…holding circuit, 75…resistor, 76…transconductance amplifier, 77…current mirror circuit, 80…not gate, 81…not gate, 82…current source, 83…N-channel M OSFET, 85…capacitor section, 86…comparator, 92…current source, 93…N-channel MOSFET, 94…NO gate, 95…capacitor section, 96…comparator, 652…OR gate, 653…oscillator, 654…comparator for pulse width modulation, 655…RS type flip-flop, 701…transistor, 702…transistor, 741…delay circuit, 742…RS type flip-flop, 743…D type flip-flop, 771…transistor, 772…transistor, 851…capacitor, 852…N-channel MOSFET, 853…capacitor, 951…capacitor, 952…N-channel MOSFET, 953…capacitor, C1…output capacitor, D1…diode, L1…inductor, L2…auxiliary winding, Q1…switching element, R1…voltage dividing resistor, R2…voltage dividing resistor, R4…sense resistor, T…transformer DETAILED DESCRIPTION

[0029] Hereinafter, the present invention will be described by way of the embodiments of the invention, but the following embodiments do not limit the invention involved in the claims. In addition, all combinations of features described in the embodiments are not necessarily essential to the solution of the invention.

[0030] [1. Configuration of power supply device]

[0031] Figure 1A power supply device 1 according to this embodiment is shown. In addition, the dotted arrows in the figure represent current.

[0032] The power supply device 1 outputs a DC output voltage V out The power supply device 1 is connected to a load of about 250 W (400 V as an example). The power supply device 1 includes an AC power supply 2, a full-wave rectifier circuit 3 for full-wave rectifying an AC input voltage from the AC power supply 2, and a boost chopper 4 for boosting a DC output voltage of the full-wave rectifier circuit 3.

[0033] [1-1. Step-up chopper 4]

[0034] The boost chopper 4 is connected between the positive output side of the full-wave rectifier circuit 3 and the ground, and in this embodiment, as an example, also functions as a power factor correction circuit. The boost chopper 4 includes: a smoothing capacitor C0 connected in parallel to the full-wave rectifier circuit 3, a transformer T and a diode D1 connected in series to the positive output side of the full-wave rectifier circuit 3, a switching element Q1 for boosting, an output capacitor C1 connected between the cathode side of the diode D1 and the ground, and a capacitor C1 for detecting the output voltage V out The voltage dividing resistors R1 and R2, the detection resistor R4, the voltage error detection and compensation circuit 5, and the power supply control device 6 are connected in parallel with the output capacitor C1.

[0035] The smoothing capacitor C0 smoothes the current flowing to the positive output side of the full-wave rectifying circuit 3 .

[0036] The transformer T has a main winding that functions as an inductor L1 provided on the positive output side of the full-wave rectifier circuit 3, and an auxiliary winding L2. The inductor L1 smoothes the current flowing to the positive output side of the full-wave rectifier circuit 3, and boosts the DC output voltage of the full-wave rectifier circuit 3 by using the induced voltage as the internal operation of the boost chopper 4 proceeds. For example, the inductor current I flowing to the primary side of the inductor L1 is L1 It can be a pulsating current of a high harmonic of 10kHz to 1000kHz. The auxiliary winding L2 is set to have a polarity opposite to that of the inductor L1. If the number of turns of the main winding L1 is set to Np and the number of turns of the auxiliary winding L2 is set to Ns, then corresponding to the case where a voltage is applied to both ends of the main winding L1, a voltage obtained by multiplying the voltage by Ns / Np is applied to both ends of the auxiliary winding L2. One end of the auxiliary winding L2 is grounded, and the other end of the auxiliary winding L2 is connected to the detection resistor R4. In this embodiment, as an example, the voltage applied to both ends of the detection resistor R4 is used as the auxiliary winding voltage V ZCD It should be noted that the auxiliary winding voltage V ZCD, the voltage applied to both ends of the auxiliary winding can be used, or the voltage applied to both ends of the detection resistor connected to the auxiliary winding, that is, the indirect voltage, can be used as in this embodiment. The details will be described later, but since a negative voltage is applied to the other end of the auxiliary winding L2 when the switching element Q1 is turned on, the current flowing to the detection resistor R4 and then the current I flowing to the zero cross detection terminal ZCD described later is ZCD Flows to the other end of the auxiliary winding L2 as a low potential.

[0037] The diode D1 functions as a reverse current prevention diode. The switching element Q1 is, for example, an N-channel MOSFET. Alternatively, the switching element Q1 may also be other MOSFETs or IGBTs. The drain-source of the switching element Q1 is electrically connected between the connection point of the inductor L1 and the anode side of the diode D1 and the ground, and the gate of the switching element Q1 is driven by a drive signal from the power supply control device 6. As an example, the switching element Q1 is driven by PWM. The output capacitor C1 removes the high-frequency component caused by the switching action from the voltage output by the power supply device 1. The voltage dividing resistors R1 and R2 are connected in series with each other.

[0038] [1-1-1. Voltage error detection and compensation circuit 5]

[0039] The voltage error detection and compensation circuit 5 removes the error signal V COMP The circuit for detecting the ripple component of the voltage error detection compensation circuit 5 is connected between the power supply control device 6 and the ground. The voltage error detection compensation circuit 5 has a capacitor C51 and an RC phase compensation circuit 50 connected in parallel. The RC phase compensation circuit 50 has a resistor R50 and a capacitor C50 connected in series. The capacitor C51 and the capacitor C50 generate an error signal V COMP , the error signal V COMP The voltage corresponds to the charge amount and is used as a comparison voltage to be compared with an oscillation wave output from an oscillator 653 described later.

[0040] [1-1-2. Power supply control device 6]

[0041] The power supply control device 6 may be, for example, an IC, and has a feedback terminal FB, an output terminal OUT, a voltage error detection compensation terminal COMP, and a zero-crossing detection terminal ZCD. It should be noted that the power supply control device 6 may also have other terminals (for example, a power supply terminal, a ground terminal, etc.). The feedback terminal FB is connected to a connection point where the voltage divider resistors R1 and R2 are connected, and the output voltage V of the power supply device 1 is received. out The feedback voltage V obtained by voltage division FBThe output terminal OUT is connected to the gate of the boost switching element Q1, and outputs a drive signal QQ that has been pulse-width modulated to drive the switching element Q1. The voltage error detection and compensation terminal COMP is connected to a voltage error detection and compensation circuit 5. The other end of the detection resistor R4 (the end on the opposite side to the auxiliary winding L2) is connected to the zero-crossing detection terminal ZCD, and receives an auxiliary winding voltage V corresponding to the auxiliary winding current flowing to the detection resistor R4. ZCD .

[0042] The power supply control device 6 is a device that causes the step-up chopper 4 to perform a power factor correction operation in a critical control mode, and ideally turns on the switching element Q1 at a time when the current flowing to the step-up chopper 4 becomes zero and the source-drain voltage Vds of the switching element Q1 becomes a minimum value. The power supply control device 6 includes a comparison voltage generating unit 61, a positive voltage clamp circuit 62, a detection unit 63, a delay adjusting unit 64, and a switch control unit 65.

[0043] [1-1-2(1). Comparison voltage generating unit 61]

[0044] The comparison voltage generating unit 61 generates a DC output voltage V outputted from the step-up chopper 4 according to the DC output voltage V out The comparison capacitors C50 and C51 are charged or discharged. In this embodiment, as an example, the comparison voltage generating unit 61 uses the feedback voltage V FB As the DC output voltage V out The comparison voltage generating unit 61 includes an error amplifier 61a. The inverting input side of the error amplifier 61a receives a feedback voltage V FB The non-inverting input side of the error amplifier 61a receives a reference voltage V corresponding to the target output voltage. 61 The error amplifier 61a may be a transconductance amplifier. The error amplifier 61a may generate and feedback a voltage V FB With reference voltage V 61 The error signal V is generated by charging or discharging the capacitors C50 and C51 of the voltage error detection and compensation circuit 5 connected to the voltage error detection and compensation terminal COMP using the charge and discharge current. COMP By using the voltage error detection compensation circuit 5 to generate an error signal V COMP , so that the ripple component contained in the output current of the error amplifier 61a is smoothed, and the error signal V COMP In a stable state, it becomes a DC voltage. The error signal V COMP It is supplied to the switch control unit 65 and the like.

[0045] [1-1-2(2). Positive voltage clamp circuit 62]

[0046] The positive voltage clamp circuit 62 clamps the voltage applied to the zero crossing detection terminal ZCD below a predetermined positive clamp voltage. For example, the positive voltage clamp circuit 62 may include a Zener diode 62a connected between the zero crossing detection terminal ZCD and ground. The cathode of the Zener diode 62a may be toward the zero crossing detection terminal ZCD side. The Zener diode 62a is connected to the auxiliary winding voltage V ZCD When the voltage is lower than the clamping voltage, no current will flow. ZCD In order to allow the current to flow when the voltage is above the clamp voltage, the voltage applied to the zero-crossing detection terminal ZCD is clamped to the clamp voltage. ZCD If it becomes high, the internal components of the power supply control device 6 will be damaged.

[0047] [1-1-2(3). Detection unit 63]

[0048] The detection unit 63 detects that the first value based on the inductor voltage becomes smaller than the threshold value. Specifically, when the switch element Q1 is turned off, the inductor voltage of the main winding decreases. Therefore, the auxiliary winding voltage V ZCD The detection unit 63 can detect the auxiliary winding voltage V ZCD That is, the detection unit 63 can detect the auxiliary winding voltage V as the first value. ZCD Here, the auxiliary winding voltage V ZCD The threshold value may be the auxiliary winding voltage V at the reference time for determining the turn-on time of the switching element Q1. ZCD (Also called zero-crossing reference voltage V th_zcd ), which may be 1 V as an example. The detection unit 63 may have a voltage V ZCD becomes less than the zero-crossing reference voltage V th_zcd It should be noted that the auxiliary winding voltage V ZCD becomes the zero-crossing reference voltage V th_zcd The moment (t VZCD＝th ) can be the inductor current I L1 The moment (t Vds＝min ) before, from time (t VZCD＝th ) to time (t Vds＝min ) can be changed according to the input voltage.

[0049] The detection unit 63 may also have a function to detect the auxiliary winding voltage V ZCD becomes less than the zero-crossing reference voltage V th_zcdThe counter can output a detection signal V that becomes high level corresponding to the situation where the count value reaches a predetermined reference number of times (for example, twice). ZCD＜th It should be noted that the details will be described later, but if the detection signal V ZCD＜th becomes high level, the switch control unit 65 turns on the switch element Q1. ZCD becomes less than the zero-crossing reference voltage V th_zcd When the number of times reaches the reference number, the switch element Q1 is turned on. ZCD becomes less than the zero-crossing reference voltage V th_zcd Different from the case where the switch element Q1 is turned on at the same time, the switch element Q1 is turned on at each reference number of times by skipping at least one time when the source-drain voltage Vds of the switch element Q1 reaches the bottom value, i.e., bottom skip control. The detection unit 63 can supply the detection signal V to the delay adjustment unit 64. ZCD＜th .

[0050] [1-1-2(4). Delay adjustment unit 64]

[0051] The delay adjustment unit 64 adjusts the delay time from the detection of the first value based on the inductor voltage (in this embodiment, as an example, the auxiliary winding voltage V ZCD ) becomes smaller than a threshold value (in this embodiment, as an example, the zero-crossing reference voltage V th_zcd ) until the switch control unit 65 turns on the switch element Q1. The auxiliary winding voltage V ZCD It can become less than the zero-crossing reference voltage V during the period when the switching element Q1 is turned off. th_zcd The delay adjustment unit 64 can adjust the delay time according to the second value based on the inductor voltage. For example, the delay time can be adjusted according to the second value during the on-time of the switch element Q1. ZCD The corresponding current is used as the second value. In this embodiment, as an example, the current I flowing to the zero-cross detection terminal ZCD is used. ZCD The delay adjustment unit 64 can adjust the delay time to the detection signal V ZCD＜th The moment when it becomes high level (t VZCD＝th ) to the inductor current I L1 The moment when the source-drain voltage Vds becomes zero and reaches a minimum value (t Vds＝min ) is adjusted in a manner consistent with the elapsed time up to ).

[0052] Here, as described above, in this embodiment, the detection unit 63 detects the auxiliary winding voltage V ZCD becomes less than the zero-crossing reference voltage Vth_zcd In addition, the auxiliary winding voltage V ZCD becomes less than the zero-crossing reference voltage V th_zcd When the count value of the number of times reaches the reference number of times of bottom skip control, the detection signal V ZCD＜th Therefore, by detecting the signal V ZCD＜th The moment when it becomes high level (t VZCD＝th ) as the delay time of the starting point to adjust the auxiliary winding voltage V ZCD becomes less than the zero-crossing reference voltage V th_zcd The time when the number of times reaches the reference number is used as the delay time of the starting point. The delay adjustment unit 64 includes an input voltage identification unit 7 and a delay circuit 8.

[0053] The input voltage recognition unit 7 is connected between the zero cross detection terminal ZCD and the switch control unit 65. The input voltage recognition unit 7 is connected between the zero cross detection terminal ZCD and the switch control unit 65. The input voltage recognition unit 7 is connected between the zero cross detection terminal ZCD and the switch control unit 65. ZCD The input voltage identification unit 7 can supply a voltage identification signal V indicating the identification result to the delay circuit 8 and the switch control unit 65. in_det_on .

[0054] The delay circuit 8 is connected between the detection unit 63 and the switch control unit 65. The delay circuit 8 outputs a signal S DLY , the signal S DLY In the case where the detection signal V from the detection unit 63 is ZCD＜th After the voltage becomes high, it becomes high after a preset delay time. The delay circuit 8 can be based on the voltage recognition signal V in_det_on The delay circuit 8 can supply an output signal to the switch control unit 65 .

[0055] [1-1-2(5). Switch control unit 65]

[0056] The switch control unit 65 controls the on / off of the switching element Q1 of the step-up chopper 4. The switch control unit 65 includes an on-timer unit 9, an OR gate 652, an oscillator 653, a pulse width modulation comparator 654, and an RS flip-flop 655.

[0057] The conduction timing section 9 outputs a signal S which becomes high level when the switch element Q1 does not turn on from the off state within a preset time. timer The conduction timing unit 9 supplies a signal S to the OR gate 652. timer .

[0058] OR gate 652 supplies a signal S from delay circuit 8 to RS flip-flop 655. DLYand S from the conduction timing unit 9 timer The resulting signal is logically ORed.

[0059] The oscillator 653 generates an oscillation wave. In the present embodiment, as an example, the oscillator 653 generates a triangle wave (as an example, a sawtooth wave) ramp Ramp as the oscillation wave. The oscillator 653 supplies the ramp Ramp to the pulse width modulation comparator 654. The oscillator 653 can start the generation of the ramp Ramp when receiving a trigger signal (as an example in the present embodiment, when the output signal QQ of a high level is output from the RS type flip-flop 655 described later), and stop the generation of the ramp Ramp and reset when the trigger signal is not received.

[0060] The pulse width modulation comparator 654 outputs a pulse width modulation signal for modulating the pulse width of the drive signal of the switching element Q1. The non-inverting input terminal of the pulse width modulation comparator 654 receives the ramp wave Ramp from the oscillator 653, and the inverting input terminal of the pulse width modulation comparator 654 receives the error signal V generated by the error amplifier 61a and the voltage error detection compensation circuit 5. COMP Therefore, the output signal of the pulse width modulation comparator 654 is smaller than the error signal V COMP When the oscillation wave is at the instantaneous value, it becomes a low level. COMP In the above case, the voltage becomes high level. The pulse width modulation comparator 654 outputs the output signal to the RS flip-flop 655 .

[0061] The set terminal S of the RS flip-flop 655 receives the output signal of the OR gate 652, and the reset terminal R of the RS flip-flop 655 receives the output signal of the pulse width modulation comparator 654. The RS flip-flop 655 outputs a high-level output signal QQ in the set state, and outputs a low-level output signal QQ in the reset state. The RS flip-flop 655 supplies the output signal QQ from the output terminal Q to the conduction timing unit 9 and the switch element Q1. It should be noted that a driver (not shown) may be provided between the RS flip-flop 655 and the switch element Q1.

[0062] According to the above power supply control device 6, according to the current I ZCD To adjust the auxiliary winding voltage V ZCD becomes less than the zero-crossing reference voltage V th_zcd Therefore, even when the input voltage changes, the inductor current I L1 The moment (t Vds=min). Therefore, it is possible to prevent input current distortion, reduce switching loss, and improve energy efficiency.

[0063] In addition, since the auxiliary winding voltage V ZCD From the zero-crossing reference voltage V th_zcd above changes to less than the zero-crossing reference voltage V th_zcd After the count value of the number of times reaches the reference number of times, the switch element Q1 is turned on, so the so-called bottom skip control is performed. Therefore, the number of switching times can be reduced to reduce switching losses and improve energy efficiency. In addition, since the delay time from when the count value reaches the reference number of times to when the switch element Q1 is turned on is adjusted, even if the input voltage changes during the bottom skip control, the inductor current I L1 The moment (t Vds＝min ) turns on the switching element Q1.

[0064] In addition, the auxiliary winding voltage V is obtained by detecting the auxiliary winding current flowing to the auxiliary winding L2 through the detection resistor R4. ZCD Since the first value based on the inductor voltage is used, the power supply control device 6 can be simplified compared to a case where a detection terminal for the input voltage is provided in the power supply control device 6 .

[0065] [2. Action waveform]

[0066] Figure 2 The auxiliary winding voltage V ZCD The waveform of the output voltage QQ of the boost chopper 4 is shown in FIG. 1 . It should be noted that “Vac” in the figure represents the AC input voltage. The auxiliary winding voltage V ZCD The switching of the switching element Q1 can be changed as shown by the bold line in the figure.

[0067] Figure 3 The inductor current I L1 , the source-drain voltage Vds of the switching element Q1, the auxiliary winding voltage V ZCD , and the output signal QQ of the RS type flip-flop 655 which is the driving signal of the switch element Q1. Figure 3 , the waveform when the AC input voltage is not switched is shown in the figure. In addition, for simplicity, the waveform when the bottom skip control is not performed is shown in the figure.

[0068] The power control device 6 controls the auxiliary winding voltage V ZCD becomes less than the zero-crossing reference voltage V th_zcd The situation is detected and from that moment (t VZCD＝th ) and then turns on the switch element Q1 after a delay time, so that the turn-on time is consistent with the inductor current IL1 The moment (t Vds＝min ) are consistent.

[0069] Figure 4 The figure shows the source-drain voltage Vds of the switching element Q1 when the AC input voltage is switched. Here, the upper figure in the figure shows the relationship between the source-drain voltage Vds and the delay time when the AC input voltage is not switched (as an example, when a rated voltage of about 100V is input). The central figure in the figure shows the relationship between the source-drain voltage Vds and the delay time when the AC input voltage becomes higher (as an example, when it is switched to a rated voltage of about 200V). The lower figure in the figure shows the relationship between the source-drain voltage Vds and the delay time when the AC input voltage becomes lower.

[0070] As shown by the thick dashed line in the figure, when the AC input voltage is switched, if the delay time is not adjusted, the switching element Q1 is turned on at a time when the source-drain voltage Vds is not at a minimum value, and the switching loss increases. In this regard, the power supply control device 6 of the present embodiment adjusts the auxiliary winding voltage V based on the inductor voltage during the on-time of the switching element Q1. ZCD By adjusting the delay time, the turn-on timing is made to coincide with the timing when the source-drain voltage Vds of the switching element Q1 reaches a minimum value, thereby reducing the switching loss.

[0071] [3. Delay adjustment unit 64]

[0072] Figure 5 The delay adjustment unit 64 is shown. In the present embodiment, when it is determined that the current I based on the inductor voltage is on during the on-time of the switching element Q1, ZCD When the current I ZCD The delay time is short when the current I during the on-period of the switching element Q1 is not equal to or greater than the reference value. ZCD The delay adjustment unit 64 includes an input voltage identification unit 7 and a delay circuit 8 , and switches which of the delay time setting values ​​corresponding to each of a plurality of rated voltages (for example, two types of 100 V and 200 V in this embodiment) is used as the delay time.

[0073] [3-1. Input voltage recognition unit 7]

[0074] The input voltage identification unit 7 is based on the current I ZCD The input voltage identification unit 7 is a recognition unit for identifying which of the multiple rated voltages the input voltage input to the step-up chopper 4 is. For example, the input voltage identification unit 7 is based on the current I during the on-period of the switching element Q1.ZCD The input voltage identifying unit 7 includes a current mirror circuit 70 , an NPN bipolar transistor 71 , a resistor 72 , a comparator 73 , and a holding circuit 74 .

[0075] The current mirror circuit 70 outputs a current I corresponding to the output current Ic of the transistor 701 on the input side from the transistor 702 on the output side. in_det Here, the current Ic is equal to the current I in_det The current ratio can be N:1.

[0076] The NPN bipolar transistor 71 is connected between the transistor 701 and the zero-cross detection terminal ZCD, and has a collector terminal on the transistor 701 side and an emitter terminal on the zero-cross detection terminal ZCD side. A fixed value of base current Ib is input to the base terminal of the bipolar transistor 71 .

[0077] Here, when the switch element Q1 is in the on state, the input current I corresponding to the inductor voltage ZCD As a result, an equal amount of current flows from the bipolar transistor 71 to the zero-cross detection terminal ZCD. ZCD =Ic+Ib. Therefore, when the switch element Q1 is in the on state, the current on the output side of the current mirror circuit 70 becomes I in_det =Ic / N=(I ZCD -Ib) / N.

[0078] Resistor 72 is used to detect the current I in_det The corresponding voltage (also called detection voltage V in_det ) is connected between the transistor 702 of the current mirror circuit 70 and the ground.

[0079] The comparator 73 identifies which of the two rated voltages the input voltage to the step-up chopper 4 is. The non-inverting input terminal of the comparator 73 is connected to the connection point between the transistor 702 and the resistor 72 and receives the detection voltage V in_det (=I in_det ×R 72 )(where R 72 The inverting input terminal of the comparator 73 receives the reference voltage V th . Reference voltage V th The voltage used to identify whether the input voltage is about 100 V or about 200 V. For example, it can be the detection voltage V when the input voltage is 100 V. in_det The detection voltage V when the input voltage is 200Vin_det The voltage between.

[0080] Thus, when the switch element Q1 is in the on state, the output signal of the comparator 73 becomes a low level when the input voltage is about 100 V, and becomes a high level when the input voltage is about 200 V. It should be noted that when the switch element Q1 is in the off state, the current I ZCD and / or current Ic, current I in_det The detection voltage V in_det The comparator 73 supplies the output signal to the holding circuit 74.

[0081] The holding circuit 74 holds the output signal of the comparator 73 when the switch element Q1 is in the on state. The holding circuit 74 receives the clock signal CLK from the clock circuit (not shown). The period of the clock signal CLK can be set to one period or half period of the AC power source 2, and can be 20ms, 10ms, etc. as an example. It should be noted that the clock circuit can have an input terminal for the output signal QQ from the RS-type flip-flop 655 to hold the output signal of the comparator 73 when the switch element Q1 is in the on state. Thus, the clock circuit can be configured to output the clock signal CLK at a predetermined period at the moment when the switch element Q1 becomes in the on state, that is, at the moment when the on time of the output signal QQ is delayed by a certain amount. The holding circuit 74 has a delay circuit 741, an RS-type flip-flop 742, and a D-type flip-flop 743.

[0082] The delay circuit 741 delays the reset timing of the RS flip-flop 742 to after the reception timing of the D flip-flop 743. The delay circuit 741 can delay the clock signal CLK and supply it to the RS flip-flop 742.

[0083] The set terminal of the RS flip-flop 742 receives the output signal of the comparator 73, and the reset terminal of the RS flip-flop 742 receives the clock signal delayed by the delay circuit 741. The RS flip-flop 742 supplies the D flip-flop 743 with the output signal from the output terminal.

[0084] The output terminal of the RS flip-flop 742 is connected to the input terminal of the D flip-flop 743. The D flip-flop 743 receives and holds the value of the output signal of the RS flip-flop 742 in synchronization with the clock timing of the clock signal CLK, and outputs an output signal V corresponding to the held value. in_det_on The D-type flip-flop 743 supplies an output signal V to the delay circuit 8 and the conduction timing unit 9. in_det_on .

[0085] According to the above holding circuit 74, when the input voltage becomes about 200V when the switch element Q1 is in the on state, the RS type flip-flop 742 is set during the on period of the switch element Q1 and the D type flip-flop 743 holds the high level signal and outputs it as the output signal V in_det_on On the other hand, if the input voltage is kept at about 100V, the RS flip-flop 742 is not set during the on-time of the switch element Q1, and the D flip-flop 743 holds the low-level signal and outputs it as the output signal V in_det_on The holding signal of the D-type flip-flop 743 is updated at each cycle of the clock signal CLK, and the RS-type flip-flop 742 is reset after being updated by the D-type flip-flop 743 according to the clock signal CLK delayed by the delay circuit 741 .

[0086] Here, the output signal V of the holding circuit 74 is in_det_on is the current I during the conduction period of the switching element Q1 ZCD The signal is supplied to the delay circuit 8 and used to adjust the delay time for turning on the switch element Q1 next time. Thus, the adjustment of the delay time for turning on the switch element Q1 next time can also be based on the current I during the on period immediately before the switching cycle of the switch element Q1. ZCD In this case, the clock circuit can set the period of the clock signal CLK not to one period or half period of the AC power source 2, but to a period that makes the turn-on time of the output signal QQ have a certain delay.

[0087] [3-2. Delay circuit 8]

[0088] The delay circuit 8 outputs the detection signal V from the detection unit 63. ZCD＜th A signal S that becomes high level after a preset delay time after becoming high level DLY , and adjust the delay time according to the recognition result obtained by the input voltage recognition unit 7. The delay circuit 8 can adjust the delay time according to the voltage recognition signal V in_det The delay circuit 8 includes inverters 80 and 81 , a current source 82 , an N-channel MOSFET 83 , a capacitor unit 85 , and a comparator 86 .

[0089] The NOT gate 80 is connected between the detection unit 63 and the gate terminal of the N-channel MOSFET 83, and converts the detection signal V from the detection unit 63 into ZCD＜th The inverted signal V is supplied to the gate terminal of the N-channel MOSFET 83. The NOT gate 81 is connected between the input voltage identification unit 7 and the capacitor unit 85, and the output signal V in_det_onThe voltage is inverted and supplied to the capacitor portion 85 .

[0090] The current source 82 is connected in series with the capacitor section 85 , and supplies a constant current to the capacitor section 85 to charge the capacitor section 85 .

[0091] The N-channel MOSFET 83 and the capacitor section 85 are connected in parallel between the current source 82 and the ground. The N-channel MOSFET 83 is connected in parallel with the detection signal V received from the NOT gate 80. ZCD＜th The N-channel MOSFET 83 allows the current from the current source 82 to flow to the capacitor section 85 to charge the capacitor section 85 in the off state, and allows the current from the current source 82 to flow and discharge the capacitor section 85 in the on state.

[0092] When the N-channel MOSFET 83 is in the off state, the capacitor unit 85 is charged and generates a charging voltage V corresponding to the charge amount. DLY85 In addition, the capacitor unit 85 is connected by the current I during the on-period of the switching element Q1. ZCD The capacitance is switched to switch which of the two delay time setting values ​​is used as the delay time. The capacitor unit 85 has a series circuit of a capacitor 851, an N-channel MOSFET 852 connected in parallel to the capacitor 851, and a capacitor 853.

[0093] The capacitor 851 is connected between the current source 82 and the ground, and is charged by the current from the current source 82. The N-channel MOSFET 852 is connected between the capacitor 853 and the ground, and is switched on according to the output signal V received from the NOT gate 81. in_det_on That is, the N-channel MOSFET 852 is gate driven by the inverted signal of the current I ZCD If the voltage V in_det Not the reference voltage V th In the above case), it is set to the on state, and the current I ZCD The capacitor 853 is connected in series with the N-channel MOSFET 852 between the current source 82 and the ground, and is charged by the current from the current source 82 when the N-channel MOSFET 852 is in the on state, and is not charged when the N-channel MOSFET 852 is in the off state.

[0094] Therefore, the current I ZCD If the current I ZCDWhen the current value becomes equal to or greater than the reference value, the capacitance of the capacitor section 85 decreases. It should be noted that the N-channel MOSFET 852 may be connected to the current source 82 side with respect to the capacitor 853.

[0095] The non-inverting input terminal of the comparator 86 receives the charging voltage V DLY85 The inverting input terminal of the comparator 86 receives the reference voltage V ref86 Here, the capacitor unit 85 and the detection signal V from the detection unit 63 ZCD＜th When the voltage V DLY85 Reaching the reference voltage V ref86 , then the output signal S DLY becomes high level and the switch element Q1 is turned on. Therefore, the capacitor section 85 starts charging to the charging voltage V DLY85 Reaching the reference voltage V ref86 The time elapsed until the switching element Q1 is turned on becomes the delay time. ZCD If the value does not exceed the reference value, the capacity of the capacitor unit 85 increases, so the charging voltage V DLY85 The rate of increase of the current I ZCD When the charging voltage V DLY85 The increasing speed becomes larger and the delay time becomes smaller.

[0096] It should be noted that, when the input voltage is about 100V and about 200V, the reference voltage V ref86 can be set to the detection signal V ZCD＜th The moment when it becomes high level (t VZCD＝th ) to the inductor current I L1 The moment when the source-drain voltage Vds becomes zero and reaches a minimum value (t Vds＝min ) when the capacitor unit 85 is charged during the time from 0 to 100 Hz. DLY85 Therefore, the inductor current I L1 The moment when the source-drain voltage Vds becomes zero and reaches a minimum value (t Vds＝min ) The output signal S of the comparator 86 DLY becomes a high level and the switching element Q1 is turned on.

[0097] According to the above delay adjustment unit 64, the current I ZCD The delay time when the current I ZCDThe delay time when the voltage does not exceed the reference value is short, so the delay time becomes smaller when the input voltage is large. Therefore, the switching element Q1 can be turned on before the source-drain voltage Vds of the switching element Q1 changes from decreasing to increasing after being turned off by the resonance of the quasi-resonant circuit having the inductor L1 and the input capacitance (CISS) of the switching element Q1. Therefore, the switching element Q1 can be turned on at the moment when the source-drain voltage Vds reliably becomes the minimum value, and the switching loss caused by the turn-on can be reliably reduced.

[0098] In addition, the current I during the on-period of the switching element Q1 ZCD , which of the delay time setting values ​​corresponding to each of the multiple rated voltages is used is switched. Therefore, even when the AC power source 2 is switched, the inductor current I L1 The moment when the source-drain voltage Vds becomes zero and reaches a minimum value (t Vds＝min ) turns on the switching element Q1.

[0099] [4. On-timer section 9]

[0100] Figure 6 The conduction timing unit 9 is shown. The conduction timing unit 9 outputs a signal S timer , the signal S timer If the switch element Q1 is not turned on from the off state within a preset time, the on-timer 9 turns on the switch element Q1 after a predetermined on-timer time has passed since the off period of the switch element Q1. Thus, for example, even during the off period of the switch element Q1, the auxiliary winding voltage V ZCD is the zero-crossing reference voltage V th_zcd The above changes are less than the zero-crossing reference voltage V th_zcd When the number of times of the on-time timing does not reach the reference number of times of the bottom skip control, the switch element Q1 is also turned on. It should be noted that, in this embodiment, as an example, the start time of the on-time timing is set as the time when the switch element Q1 is turned off, but it can also be the auxiliary winding voltage V ZCD From the initial zero-crossing reference voltage V th_zcd above changes to less than the zero-crossing reference voltage V th_zcd The current I during the on-time of the switching element Q1 can be used to ZCD , the conduction timing time is adjusted by the delay adjustment unit 64. As an example, the conduction timing unit 9 can be based on the voltage recognition signal V from the delay adjustment unit 64. in_det, and which of the two set values ​​of the on-timer time corresponding to the rated voltage of about 100 V and about 200 V is switched to be used as the on-timer time. The on-timer unit 9 has a current source 92, an N-channel MOSFET 93, a NOT gate 94, a capacitor unit 95 and a comparator 96.

[0101] The current source 92 is connected in series with the capacitor unit 95 , and supplies a constant current to the capacitor unit 95 to charge the capacitor unit 95 .

[0102] The N-channel MOSFET 93 is connected between the current source 92 and the ground in parallel with the capacitor unit 95. The N-channel MOSFET 93 is gate-driven according to the output signal QQ from the RS-type flip-flop 655 of the switch control unit 65. Thus, when the output signal QQ is in a low level state, that is, when the switch element Q1 is in an off state, the N-channel MOSFET 93 is also turned off, and the current from the current source 92 flows to the capacitor unit 95 to charge the capacitor unit 95. When the output signal QQ is in a high level state, that is, when the switch element Q1 is in an on state, the N-channel MOSFET 93 is also turned on, and the current from the current source 92 flows and the capacitor unit 95 is discharged.

[0103] The NOT gate 94 is connected between the input voltage recognition unit 7 and the capacitor unit 95, so that the output signal V in_det_on The voltage is inverted and supplied to the capacitor portion 95 .

[0104] When the N-channel MOSFET 93 is in the off state, the capacitor 95 is charged and generates a charge voltage V corresponding to the charge amount. DLY95 In addition, the capacitor unit 95 is connected by the current I during the on-period of the switching element Q1. ZCD The capacitance is switched to switch which of the two set values ​​of the on-time timing is used as the on-time timing. The capacitor unit 95 includes a capacitor 951 and a series circuit of an N-channel MOSFET 952 and a capacitor 953 connected in parallel to the capacitor 951.

[0105] The capacitor 951 is connected between the current source 92 and the ground, and is charged by the current from the current source 92. The N-channel MOSFET 952 is connected between the capacitor 953 and the ground, and is switched on according to the output signal V received from the NOT gate 94. in_det_on That is, the N-channel MOSFET 952 is gate driven by the inverted signal of the current I ZCD If the detection voltage V in_det Does not become the reference voltage V thIn the above case), it is set to the on state, and the current I ZCD The capacitor 953 is connected in series with the N-channel MOSFET 952 between the current source 92 and the ground, and is charged by the current from the current source 92 when the N-channel MOSFET 952 is in the on state, and is not charged when the N-channel MOSFET 952 is in the off state.

[0106] Therefore, the current I ZCD If the current I ZCD When the value becomes equal to or greater than the reference value, the capacitance of the capacitor section 95 decreases. It should be noted that the N-channel MOSFET 952 may be connected to the current source 92 side with respect to the capacitor 953 .

[0107] The non-inverting input terminal of the comparator 96 receives the charging voltage V DLY95 The inverting input terminal of the comparator 96 receives the reference voltage V ref96 Here, if the charging voltage V DLY95 Reaching the reference voltage V ref96 , then the output signal S timer becomes high level and the switch element Q1 is turned on. Therefore, the capacitor section 95 starts charging to the charging voltage V DLY95 Reaching the reference voltage V ref96 The time elapsed until the conduction timing is the conduction timing time. ZCD If the value does not exceed the reference value, the capacity of the capacitor unit 95 increases, so the charging voltage V DLY95 The rate of increase of the current I ZCD When the charging voltage V DLY95 The increasing speed becomes larger and the delay time becomes smaller.

[0108] It should be noted that, when the input voltage is about 100V and about 200V, the reference voltage V ref96 can be set to the value from the time the switch element Q1 is turned off to the time the inductor current I L1 The charging voltage V is the same as that when the capacitor 95 is charged only during the time from when the reference number of times (twice in the present embodiment) in the bottom skip control becomes zero and the source-drain voltage Vds of the switching element Q1 becomes the minimum value. DLY95 Therefore, even if the auxiliary winding voltage V ZCD changes to be less than the zero-crossing reference voltage V th_zcdThe number of times does not reach twice, and the high-level signal S is not output from the delay circuit 8 DLY In the case of L1 The moment when the source-drain voltage Vds becomes zero and reaches a minimum value (t Vds＝min ) makes the output signal S of the comparator 96 timer becomes a high level and the switching element Q1 is turned on.

[0109] According to the above conduction timing section 9, even if the auxiliary winding voltage V ZCD From the zero-crossing reference voltage V th_zcd above changes to less than the zero-crossing reference voltage V th_zcd If the number of times does not reach the reference number in the bottom skip control, the inductor current I L1 The moment (t Vds＝min ) to reliably turn on the switching element Q1.

[0110] [5.Action]

[0111] Figure 7 The following is a diagram showing a partial operation of the power supply control device 6. The power supply control device 6 reduces switching loss and improves energy efficiency by performing the processes of steps S11 to S15.

[0112] In step S11, the switch control unit 65 controls the on / off of the switch element Q1 of the step-up chopper 4. For example, the switch control unit 65 controls the output signal S from the delay adjustment unit 64. DLY and the output signal S from the conduction timing unit 9 timer When at least one of the signal levels V is high, the switch element Q1 is turned on accordingly. In addition, the switch control unit 65 controls the switch element Q1 so that the switch element Q1 turns on when the ramp wave Ramp is greater than the error signal V COMP becomes OFF during the period.

[0113] In step S13, the detection unit 63 detects the auxiliary winding voltage V ZCD becomes less than the zero-crossing reference voltage V th_zcd The detection unit 63 can detect the auxiliary winding voltage V only at the reference number of times in the bottom skip control. ZCD becomes less than the zero-crossing reference voltage V th_zcd The situation is detected and the detection signal V ZCD＜th Set to high level.

[0114] In step S15, the delay adjustment unit 64 adjusts the delay according to the current I during the on-period of the switching element Q1. ZCD To adjust the auxiliary winding voltage V detected during the off period of the switching element Q1ZCD becomes less than the zero-crossing reference voltage V th_zcd The delay time from when the switching element Q1 is turned on in the process of step S11. In the present embodiment, the delay adjustment unit 64 may be based on the current I ZCD To switch from the detection signal V ZCD＜th =The delay time from when the current I becomes high to when the switching element Q1 is turned on. ZCD , and which of the delay time setting values ​​corresponding to the rated voltages of about 100V and 200V is used as the delay time is switched. ZCD The delay time is adjusted, and at the time corresponding to the adjusted delay time, the output signal S from the delay adjustment unit 64 is DLY becomes high level.

[0115] In addition, the delay adjustment unit 64 further adjusts the current I during the on-period of the switching element Q1 based on the current I ZCD , adjust the conduction timing time. Thus, according to the current I ZCD To adjust the conduction timing, even during the off period of the switch element Q1, the auxiliary winding voltage V ZCD From the zero-crossing reference voltage V th_zcd above changes to less than the zero-crossing reference voltage V th_zcd When the number of times does not reach the reference number of times for the bottom skip control, the output signal S from the conduction timing unit 9 timer Also becomes high level.

[0116] Thereafter, the power supply control device 6 repeats the processing of steps S11 to S15.

[0117] [6. Modifications]

[0118] Figure 8 The input voltage identification unit 7A of a modified example is shown. The input voltage identification unit 7A further includes a resistor 75 and a transconductance amplifier 76. The resistor 75 is connected to the base terminal of the bipolar transistor 71 and converts the base current Ib into a voltage. The non-inverting input terminal and the inverting input terminal of the transconductance amplifier 76 are connected to both ends of the resistor 75, and a current (=Ib×R 75 ×gm)(where R 75 is the resistance value of resistor 75) is output to the connection point between transistor 702 and resistor 72.

[0119] According to the above input voltage recognition unit 7A, the detection voltage detected by the resistor 72 and input to the non-inverting input terminal of the comparator 73 is V in_det =(I in_det +Ib×R 75×gm)×R 72 Therefore, with Figure 4 Unlike the input voltage identification unit 7 shown in the figure, the input voltage can be identified by also taking the base current Ib into consideration, so the input voltage can be identified accurately. 75 , the transconductance (gm) of the transconductance amplifier 76, and the current ratio N of the current mirror circuit 70 can be set to satisfy R 75 ×gm=1 / N. In this case, the detection voltage is V in_det =I ZCD ×R 72 / N.

[0120] Fig. 9 Another modified example of the input voltage identification unit 7B is shown. The input voltage identification unit 7B further includes a current mirror circuit 77. A transistor 771 on the input side of the current mirror circuit 77 is connected to the base terminal of the bipolar transistor 71, and a transistor 772 on the output side of the current mirror circuit 77 is connected to the connection point between the transistor 702 and the resistor 72. The current ratio between the input side and the output side of the current mirror circuit 77 can be N:1.

[0121] According to the above input voltage recognition unit 7B, the detection voltage detected by the resistor 72 and input to the non-inverting input terminal of the comparator 73 is V in_det =(Ic / N+Ib / N)×R 72 =I ZCD ×R 72 / N. Therefore, Figure 4 Unlike the input voltage identification unit 7 shown, the input voltage can be identified by also taking the base current Ib into consideration, and thus the input voltage can be accurately identified.

[0122] [7. Other Modifications]

[0123] In the above-mentioned embodiment, the auxiliary winding L2 is wound with a polarity opposite to that of the inductor L1, and the input voltage identification unit 7 is based on the current I ZCD The auxiliary winding voltage V is indirectly detected by multiplying the input voltage of the main winding L1 during the switch-on period of the switching element Q1 by Ns / Np. ZCD Specifically, the current I flowing out of the power supply control device 6 ZCDThe input voltage is converted into a voltage and the AC input voltage is identified. However, during the switch-off period of the switching element Q1, a voltage obtained by multiplying the difference between the input voltage and the output voltage by the turns ratio (Ns / Np) appears in the auxiliary winding L2, so based on this voltage, the current flowing into the power control device 6 can be converted into a voltage and the AC input voltage can be identified. That is, the input voltage identification unit 7 can convert the current flowing into the power control device 6 during the switch-off period of the switching element Q1 into a voltage to identify the AC input voltage. In this case, the delay adjustment unit 64 can adjust the delay time based on the second value of the inductor voltage during the switch-off period of the switching element Q1 (the current flowing into the power control device 6), and can also adjust the conduction timing time based on the second value.

[0124] Furthermore, although the case where the AC power supply 2 and the full-wave rectifier circuit 3 are provided in the power supply device 1 has been described, at least one of the AC power supply 2 and the full-wave rectifier circuit 3 may not be provided in the power supply device 1 but may be externally connected to the power supply device 1 .

[0125] Furthermore, the case where the power supply control device 6 includes the comparison voltage generation unit 61 and the positive voltage clamp circuit 62 has been described. However, the power supply control device 6 may not include at least one of the comparison voltage generation unit 61 and the positive voltage clamp circuit 62 .

[0126] In addition, the power supply control device 6 has been described as adjusting the delay time by recognizing which of the multiple rated voltages the AC input voltage is. However, the delay time may be adjusted based on the current I during the on-period of the switching element Q1. ZCD The delay time is adjusted according to the change of the AC input voltage. ZCD As an example, when the rated voltage of the AC power source 2 is about 100V, the power supply control device 6 can detect whether the AC input voltage is less than 100V, 100V to 105V, 105V to 110V, or more than 110V, and adjust the delay time. In this case, when the AC input voltage changes within the allowable range, the inductor current I L1 The switching element Q1 is turned on at the moment when Vds becomes zero and the source-drain voltage Vds of the switching element Q1 becomes a minimum value.

[0127] In addition, the delay circuit 8 has been described as adjusting the delay time by switching the number of chargeable capacitors in the capacitor section 85, but the reference voltage V ref86Similarly, the case where the conduction timing section 9 adjusts the conduction timing time by switching the number of chargeable capacitors in the capacitor section 95 has been described, but the reference voltage V ref96 To adjust the on-time.

[0128] In addition, the case where the power supply control device 6 performs the bottom skip control is described, but the power supply control device 6 may not perform the bottom skip control. In this case, the detection unit 63 may output the auxiliary winding voltage V ZCD becomes less than the zero-crossing reference voltage V th_zcd The detection signal V ZCD＜th .

[0129] In addition, although the first value based on the inductor voltage is set to the auxiliary winding voltage V ZCD , and set the second value based on the inductor voltage as the current I ZCD Although the first value is described above, it can also be set to the inductor voltage itself, or to another value based on the inductor voltage. For example, the first value can also be set to the current I ZCD , set the second value to the auxiliary winding voltage V ZCD In addition, the first value and the second value may be the same value.

[0130] The present invention has been described above using the embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments. It is clear to those skilled in the art that various changes or improvements can be made to the above embodiments. According to the description of the claims, the various changes or improvements can also be included in the technical scope of the present invention.

[0131] It should be noted that the execution order of each process such as actions, processes, steps and stages in the devices, systems, programs and methods shown in the claims, specifications and drawings can be implemented in any order unless "earlier than" or "in advance" is specifically stated, and as long as the previous processing results are not used in the subsequent processing. Even if the action flow in the claims, specifications and drawings is described using "first" or "next" for convenience, it does not mean that it must be implemented in this order.

Claims

1. A power supply control device, characterized in that: have: A switch control unit that controls the on and off of the switch element of the step-up chopper; a detection unit configured to detect that a first value becomes smaller than a threshold value, the first value being a value based on an inductance voltage of an inductor of the step-up chopper during an off period of the switching element; as well as A delay adjustment unit adjusts a delay time from when the detection unit detects that the first value becomes smaller than the threshold value until the switch control unit turns on the switch element, based on a second value of the inductor voltage during an on period or an off period of the switch element.

2. The power supply control device according to claim 1, characterized in that: The delay adjustment unit determines whether the second value is equal to or greater than a reference value during the on-period of the switching element. When it is determined that the second value is equal to or greater than the reference value, the delay adjustment unit shortens the delay time to be shorter than the delay time when the second value is not equal to or greater than the reference value.

3. The power supply control device according to claim 1, characterized in that: The switch control unit turns on the switch element in response to a case where the number of times the first value changes from greater than or equal to the threshold to less than the threshold reaches a predetermined number of times, The delay adjustment unit adjusts a delay time from when the first value changes from greater than or equal to the threshold to less than the threshold a predetermined number of times to when the switch control unit turns on the switch element.

4. The power control device according to claim 2, characterized in that: The switch control unit turns on the switch element in response to a case where the number of times the first value changes from greater than or equal to the threshold to less than the threshold reaches a predetermined number of times, The delay adjustment unit adjusts a delay time from when the first value changes from greater than or equal to the threshold to less than the threshold a predetermined number of times to when the switch control unit turns on the switch element.

5. The power supply control device according to claim 3, characterized in that: The switch control unit includes a conduction timing unit that turns on the switch element after a predetermined conduction timing time. The delay adjustment unit further adjusts the on-time period based on the second value.

6. The power supply control device according to claim 4, characterized in that: The switch control unit includes a conduction timing unit that turns on the switch element after a predetermined conduction timing time. The delay adjustment unit further adjusts the on-time period based on the second value.

7. The power supply control device according to any one of claims 1 to 6, characterized in that: The step-up chopper includes a transformer having an auxiliary winding and a main winding functioning as the inductor. The detection section uses the auxiliary winding voltage as the first value.

8. The power supply control device according to claim 7, characterized in that: The delay adjustment section uses a current corresponding to the auxiliary winding voltage as the second value.

9. The power supply control device according to any one of claims 1 to 6, characterized in that: The delay adjustment unit switches which of the delay time setting values ​​corresponding to each of a plurality of rated voltages is used as the delay time based on the second value during the on-period of the switching element.

10. The power supply control device according to claim 7, characterized in that: The delay adjustment unit switches which of the delay time setting values ​​corresponding to each of a plurality of rated voltages is used as the delay time based on the second value during the on-period of the switching element.

11. The power supply control device according to claim 8, characterized in that: The delay adjustment unit switches which of the delay time setting values ​​corresponding to each of a plurality of rated voltages is used as the delay time based on the second value during the on-period of the switching element.

12. The power supply control device according to any one of claims 1 to 6, characterized in that: The delay adjustment unit adjusts the delay time according to a change in the second value accompanying a change in an AC input voltage from a power source that supplies electric power to the step-up chopper.

13. The power supply control device according to claim 7, characterized in that: The delay adjustment unit adjusts the delay time according to a change in the second value accompanying a change in an AC input voltage from a power source that supplies electric power to the step-up chopper.

14. The power supply control device according to claim 8, characterized in that: The delay adjustment unit adjusts the delay time according to a change in the second value accompanying a change in an AC input voltage from a power source that supplies electric power to the step-up chopper.

15. The power supply control device according to claim 9, characterized in that: The delay adjustment unit adjusts the delay time according to a change in the second value accompanying a change in an AC input voltage from a power source that supplies electric power to the step-up chopper.

16. The power supply control device according to claim 10, characterized in that: The delay adjustment unit adjusts the delay time according to a change in the second value accompanying a change in an AC input voltage from a power source that supplies electric power to the step-up chopper.

17. The power supply control device according to claim 11, characterized in that: The delay adjustment unit adjusts the delay time according to a change in the second value accompanying a change in an AC input voltage from a power source that supplies electric power to the step-up chopper.

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