Switching power device

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a switching power supply device with a ripple removing function in consideration of the temperature at which the phase compensation constant is changed by a temperature sensitive element while the ESR of the electrolytic capacitor increases and the ripple component increases due to a change in the environmental temperature.

【0002】

[Conventional technology]

FIG. 13 is a schematic configuration diagram of a conventional current resonance type switching power supply. The current resonance type switching power supply shown in FIG. 13 has a DC power supply 1, a start-up resistor 2 having one end connected to the DC power supply 1, and one end connected to the other end of the start-up resistor 2 and the other end to the DC power supply 1. It is equipped with a connected control unit power supply capacitor 3.

【0003】

It also includes a control unit 4 (also referred to as a control IC 4) that sends out control signals a1 and a2 (pulse signals) for turning on and off the switching elements 5 and 6. A capacitor 8 is connected in parallel to the switching element 6 described above.

【0004】

A photocoupler 7 is connected to this control unit 4. The photocoupler 7 is composed of a light emitting element 7a and a phototransistor 7b. The light emitting element 7a is provided on the secondary side, and the phototransistor 7b is provided on the input side and connected to the control IC 4. That is, the photocoupler 7 detects the output voltage on the secondary side and outputs a feedback signal corresponding to the level of this output voltage to the control IC 4. Further, in the control unit 4, a phase compensation circuit on the primary side in which the resistor 16 and the capacitor 15 are connected in series is connected in parallel to the phototransistor 7b.

【0005】

The control IC 4 has a start voltage VC1 (START) and an oscillation stop voltage VC2 (STOP), and inputs the voltage VCC at the connection point between the control IC power supply capacitor 3 and the start resistor 2 as a power supply, and this power supply voltage Oscillation starts when VCC reaches the above-mentioned start-up voltage VC1 (VC1> VC2), and stops when the power supply voltage VCC reaches the oscillation stop voltage VC2.

【0006】

That is, the control IC 4 continues to oscillate until the oscillation stop voltage VC2 or less even if the terminal voltage VCC of the control IC power supply capacitor 3 becomes the start voltage VC1 or less.

【0007】

The transformer 9 is composed of a primary winding 9a, an auxiliary winding 9b, and output windings 9c and 9d, and the output windings 9c and 9d and the auxiliary winding 9b are roughly coupled with the primary winding in order to have leakage inductance. Has been made.

【0008】

Further, one end of the primary winding 9a is connected to the connection point between the switching element 5 and the switching element 6, and the other end is connected to one end of the current resonance capacitor 10.

【0009】

The other end of the current resonance capacitor 10 is connected to one end of the auxiliary winding 9b. Further, one end of the auxiliary winding 9b is connected to a capacitor 8, a switching element, a photodiode 7b, a control IC 4, a control IC power supply capacitor 3, and a DC power supply 1.

【0010】

Further, the other end of the auxiliary winding 9b is connected to the connection point between the control IC power supply capacitor 3 and the starting resistor 2 via the diode 11.

【0011】

On the other hand, one end of the output winding 9c is connected to the anode of the rectifying diode 12a, and the other end of the output winding 9c is connected to the anode of the rectifying diode 12b via the output winding 9d. The cathodes of the rectifier diodes 12a and 12b are connected to each other, and this connection point is connected to the output terminal a. Further, the other end of the output winding 9c and one end of the output winding 9d are connected, and this connection point A is connected to the output end b. A load 15 is connected to the output terminals a and b.

【0012】

Further, a smoothing capacitor 13 is provided between the cathode of the rectifier diode 12a and the connection point A.

【0013】

A secondary voltage control circuit 27 is connected in parallel to the smoothing capacitor 13. The secondary side voltage control circuit 27 connects the light emitting element 7a of the photocoupler 7, the resistor 22 and the shunt regulator 24 in series, and is connected in parallel to the smoothing capacitor 13. Further, a capacitor 23 is connected between the cathode and the gate of the shunt regulator 24, and a capacitor 19 and a resistor 20 are connected in series between the reference point of the shunt regulator 24 from the connection point between the smoothing capacitor 13 and the anode of the light emitting element 7a of the photocoupler 7. The connected secondary side phase compensation circuit 21 is connected.

【0014】

Furthermore, the rectifying diode 12a cathode of over de and between the output terminal a inductance 18 is provided, between the output terminal and the connection point A of the inductance 18, a series circuit composed of the variable resistor 25 and a resistor 26. Is provided.

【0015】

The operation of the conventional switching power supply configured as described above will be described below.

【0016】

When the DC power supply 1 is turned on, the control IC power supply capacitor 3 is charged via the start-up resistor 2, and the terminal voltage VCC of the control IC power supply capacitor 3 increases. When this voltage Vcc reaches the predetermined start-up voltage VC1, the control IC4 starts oscillating, turns the switching elements 5 and 6 on and off, and outputs the primary winding 9a and the oscillation frequency f based on the resonance capacitor 10. Obtain on the next side (output windings 9c, 9d).

【0017】

This output is rectified and smoothed by the rectifying diodes 12a and 12b and the smoothing capacitor 13, and the output current Io is supplied to the load 15 via the output terminals a and b.

【0018】

At this time, the secondary side voltage control circuit 27 detects the output voltage Vo on the secondary side, adjusts the output voltage Vo so that the detected voltage Vo falls within a predetermined fluctuation range, and photographs the current based on this adjustment amount. While flowing through the light emitting element 7a of the coupler 7, the phase compensation circuit 21 on the secondary side reduces high-frequency ripple.

【0019】

On the other hand, in the control IC 4 provided on the primary side, the photodiode 7b of the photocoupler 7 inputs a monitor signal based on the light receiving level, and sends out the duty ratio control signals a and b based on this monitor signal to the secondary side. The output voltage Vo (output current Io) of is made constant.

【0020】

[Problems to be Solved by the Invention]

However, since the electrolytic capacitors 13 and 28 are used on the secondary side as described above, the influence of temperature cannot be ignored.

【0021】

In general, as shown in FIG. 14, the equivalent resistance ESR of an electrolytic capacitor has a high ESR when the temperature is low and a low ESR when the temperature is high.

【0022】

That is, the ESRs of the electrolytic capacitors 13 and 28 on the secondary side are high when the temperature is low and low when the temperature is high, in response to changes in the environmental temperature and operating temperature.

【0023】

In particular, the change in ESR at temperatures below 20 ° C is very large, and the change in ESR at -25 ° C is about 10 times that of 20 ° C.

【0024】

For this reason, the stability of the control system is affected and unstable operation often occurs at low or high temperatures due to a large change in the phase angle of the control system, an increase in the output ripple voltage at low temperatures, and a decrease at high temperatures. There was a challenge.

【0025】

As a countermeasure, generally, the phase correction constant of the error amplifier of the control system circuit may be adjusted or the gain of the error amplifier may be lowered to deal with it. However, when trying to suppress the output ripple voltage, an error in the frequency of the output ripple voltage is obtained. It is necessary to increase the gain of the amplifier, and the control circuit tends to become unstable due to changes in the environmental temperature and operating temperature, which may cause hunting or oscillation due to sudden changes in the output current or changes in the output current.

【0026】

The main reason is that the phase correction constants of the error amplifier differ in the stable operating constant range between high temperature and low temperature due to changes in the ESR of the electric field capacitors 13 and 28 on the secondary side.

【0027】

That is, when an error amplifier is used, there is a problem that it is not easy to determine a constant for phase correction.

【0028】

Therefore, even if the error amplifier and the secondary side voltage control circuit are provided, the negative feedback that controls the output voltage to be constant cannot be stably applied with the voltage gain increased, and the stability of the negative feedback circuit is improved. , There is a problem that it is difficult to achieve both reduction of output ripple voltage.

【0029】

The present invention has been made to solve the above problems, and is a ripple removal function considering the temperature that enables deeper negative feedback to be stably applied in a wide temperature range in consideration of the temperature characteristics of the electrolytic capacitor. The purpose is to obtain a switching power supply with.

【0030】

[Means for solving problems]

The switching power supply according to claim 1 is configured to intermittently supply direct current to the primary side of the transformer and rectify and smooth the alternating current obtained on the secondary side of the transformer to obtain a constant output. The gist of the power supply is to have a phase correction means that performs optimum phase compensation at each temperature by utilizing a change in resistance value depending on the temperature of the temperature sensitive element.

【0031】

That is, since the resistance value of the temperature-sensitive element provided on the output side changes depending on the environmental temperature (low temperature, high temperature), the phase advance of the ripple component due to the electrolytic capacitor is suppressed at low temperature (gain decrease), and the phase of the ripple component at high temperature. The lead is increased (gain is increased). Therefore, on the output side, deeper optimum phase compensation is performed at low temperature and high temperature.

【0032】

The switching power supply according to claim 2 is configured to intermittently supply direct current to the primary side of the transformer and rectify and smooth the alternating current obtained on the secondary side of the transformer to obtain a constant output. The power supply has a phase correction means that detects the output on the secondary side and keeps it constant, and also performs optimum phase compensation at each temperature by utilizing the change in the resistance value depending on the temperature of the temperature sensitive element. The gist is to have an output value control circuit.

【0033】

In the second embodiment, a control unit that intermittently supplies direct current to the primary side of the transformer according to a light emitting signal corresponding to an output value on the secondary side, and an alternating current obtained on the secondary side are used. In a switching power supply device having an output value control circuit that smoothes and makes the smoothed output constant while emitting a light emitting signal according to the control amount at this time, the output value control circuit is provided with a phase correction means, and the phase is provided. The correction means passes the ripple component contained in the smoothing output through the temperature-sensitive element, and the change in resistance in the temperature-sensitive element performs optimal phase compensation according to the temperature change.

【0034】

That is, by providing a phase correction means having a temperature sensitive element in the output value control circuit on the secondary side (output side) and utilizing the fact that the resistance value of this temperature sensitive element changes according to the environmental temperature, Optimal phase compensation is performed for the ripple component contained in the smooth output.

【0035】

Therefore, on the output side (secondary side), the phase advance is suppressed (gain decrease) at low temperature and the phase advance is increased (gain increase) at high temperature, so that the deeper optimum phase is obtained at low temperature and high temperature. Compensation is provided.

【0036】

The switching power supply according to claim 3 has a control unit that receives a control signal output from an output value control circuit on the secondary side and turns on / off the switching element, and intermittently supplies direct current to the primary side of the transformer. In a switching power supply configured to rectify and smooth the AC obtained on the secondary side of the transformer to obtain a constant output, a control signal to detect the output on the secondary side and keep it constant. It has an output value control circuit that outputs, a control unit that turns on / off the switching element in response to the control signal, and a switching element, and the control unit utilizes a change in resistance value due to the temperature of the temperature sensitive element. Therefore, it is a gist to have a phase correction means that performs optimum phase compensation at each temperature.

【0037】

In the third embodiment, a control unit that intermittently supplies direct current to the primary side of the transformer according to a light emission signal corresponding to the output value on the secondary side, and an alternating current obtained on the secondary side are used. In a switching power supply provided with an output value control circuit that emits a light emitting signal according to the control amount at this time while smoothing and making the smoothed output constant, a phase correction means is provided on the control unit side to compensate the phase. The means includes a phase correction unit that receives the light emission signal and transmits the control signal that has undergone phase compensation according to a change in the resistance value of the temperature sensitive element to the control unit as a feedback signal.

【0038】

That is, by providing a phase correction means having a temperature sensitive element in the phase correction unit on the input side (primary side) and utilizing the fact that the resistance value of this temperature sensitive element changes according to the ambient temperature, the primary side At low temperatures, the phase advance is suppressed (gain decrease), and at high temperatures, the phase advance is increased (gain increase).

【0039】

That is, on the input side (primary side), optimum phase compensation is performed at low temperature and high temperature.

【0040】

According to claim 4, when the resistance value of the temperature sensitive element changes due to the ambient temperature, the phase compensation selects a phase correction constant on the high temperature side or a phase correction constant on the low temperature side according to the change value, and the selection is made. The gist is to perform phase compensation with the phase correction constant.

【0041】

In the fourth embodiment, the phase correction constant at low temperature is set to a resistance value that suppresses the phase advance and lowers the gain. Further, the phase correction constant at high temperature is preferably set to a resistance value that increases the phase advance and the gain.

【0042】

Further, the transformer according to each of the above claims is of a resonance type, and the control unit uses a direct current input to the transformer and a voltage of an electrolytic capacitor for charging the voltage of the auxiliary winding of the transformer as a power source, and the voltage is the first. When the voltage reaches the above voltage, the switching element is controlled on and off based on the received signal.

【0043】

Further, when the voltage of the electrolytic capacitor reaches the second voltage or less, which is equal to or lower than the first voltage, it is preferable to stop the on / off.

【0044】

BEST MODE FOR CARRYING OUT THE INVENTION

<Embodiment 1> In the present embodiment 1, a temperature sensitive element is provided in the secondary voltage control circuit, and the optimum phase characteristics (at high temperature and low temperature) are obtained with respect to changes in environmental temperature and operating temperature. By performing temperature correction, it is possible to stably apply deeper negative feedback to the switching power supply over a wide temperature range.

【0045】

Therefore, the switching power supply device having the configuration shown in FIG. 1 is used. In FIG. 1, the same items as those in FIG. 13 will not be described.

【0046】

As shown in FIG. 1, the output side voltage control circuit 31 on the output side (also referred to as the secondary side) is provided with a thermistor 33 (temperature sensitive element TH) to suppress the amount of phase lead signal at low temperature and phase at high temperature. Increase the amount of lead signal.

【0047】

Next, the configuration of the output side voltage control circuit 31 will be described. The output side voltage control circuit 31 connected in parallel to the output side electrolytic capacitor 13 includes a light emitting element 7a of the photocoupler 7 as in the conventional case, a resistor 22, and a shunt regulator 24.

【0048】

Further, in the present embodiment, the phase compensation circuit 32 with temperature compensation in which the capacitor 19, the thermistor 33, and the resistor 20 are connected in series is provided.

【0049】

That is, the output side voltage control circuit 31 detects the secondary side output voltage Vo by providing the phase compensation circuit 32 with temperature compensation, and adjusts the output voltage Vo so that the detected voltage Vo falls within a predetermined fluctuation range. At the same time, a current based on this adjustment amount is passed through the light emitting element 7a of the photocoupler 7, while the phase compensation circuit 32 with temperature compensation increases or decreases the phase lead signal based on the temperature with high frequency ripple.

【0050】

The operation of the switching power supply of the first embodiment configured as described above will be described below.

【0051】

When the DC power supply 1 is turned on, the control IC power supply capacitor 3 is charged via the start-up resistor 2, and the terminal voltage VCC of the control IC power supply capacitor 3 increases. When this voltage Vcc reaches the predetermined start-up voltage VC1, the control IC4 starts oscillating, turns the switching elements 5 and 6 on and off, and outputs the primary winding 9a and the oscillation frequency f based on the resonance capacitor 10. Get to the next side.

【0052】

This output is rectified and smoothed by the rectifying diodes 12a and 12b and the smoothing capacitor 13. Then, the light emitting element 7a, the resistor 22, and the shunt regulator 24 of the output side voltage control circuit 31 keep the output voltage Vo on the secondary side at the rated output, and at the same time, the signal amount of the shunt regulator for keeping the rated output. The corresponding light is emitted from the light emitting element 7a.

【0053】

Further, the ripple component of the electrolytic capacitor 13 of the output voltage Vo is removed by the filter including the capacitor 19, the thermistor 33, and the resistor 20 constituting the phase compensation circuit 32 with temperature compensation of the output side voltage control circuit 31.

【0054】

The phase compensation circuit 32 having this temperature compensation element superimposes an output ripple component on the reference terminal of the shunt regulator 24 to further increase the negative feedback of the phase compensation and stabilize the control.

【0055】

Further, this shunt regulator 24 has a reference potential (vs), and when the potential vh at the other input end exceeds the reference potential vs, the potential of the cathode is lowered to send a current to the light emitting element 7a of the photocoupler 7. Shed.

【0056】

Therefore, when the environmental temperature is low and the environmental temperature is high, the operation described below is performed.

【0057】

(Operation at low temperature) When the temperature is low, the ESR of electrolytic capacitors 3, 13 and 28 increases as shown in Fig. 14. Therefore, the ripple component on the output side increases, but since the phase compensation circuit 32 with temperature compensation of the output side voltage control circuit 31 includes the thermistor 33, the resistance value of the thermistor 33 increases as the temperature decreases. ..

【0058】

That is, the amount of the output ripple component superimposed on the reference terminal of the shunt regulator 24 is reduced, and the phase lead signal of the shunt regulator is reduced.

【0059】

(Operation at high temperature) At high temperature, the ESR of the electrolytic capacitor 13 decreases and the resistance value of the thermistor 33 decreases.

【0060】

That is, when the ripple component decreases at high temperature, the resistance value of the thermistor 33 decreases, so that the ripple component to the reference terminal of the shunt regulator 24 is increased and the phase lead signal amount is kept constant. To do.

【0061】

As a result, the potential vh at the other input end of the shunt regulator 24 becomes higher than the reference potential vs. the shunt regulator 24 causes a large current to flow to generate light from the light emitting element 7a.

【0062】

On the other hand, the photodiode 7b of the phase compensation circuit 17 on the input side receives the light from the light emitting element 7a, and the control unit 4 oscillates at a duty ratio based on this light receiving amount to cause the switching elements 5 and 6 (power MOSFET). Turn it off and off. As a result, the output of the oscillation frequency f based on the primary winding 9a and the resonance capacitor 10 is induced to the secondary side (output windings 9c and 9d), and is rectified and smoothed by the rectifying diodes 12a and 12b and the smoothing capacitor 13 and rated. Get the output voltage Vo.

【0063】

The thermistor 33 used in the output-side voltage control circuit 31 described above may have a connection configuration as shown in FIG.

【0064】

In FIG. 3A, the light emitting element 7a, the thermistor 33, and the shunt regulator 24 are connected in series, and the capacitor 19, the resistor 20, and the capacitor 23 are connected to the series circuit including the light emitting element 7a and the thermistor 33. Series circuits are connected in parallel. Further, the connection point between the resistor 20 and the capacitor 23 is connected to the reference terminal of the shunt regulator 24.

【0065】

That is, when the ESR of the electrolytic capacitor increases at low temperature and the ripple component increases, the resistance value of the thermistor 33 increases at low temperature, so that the current to the cathode of the shunt regulator 24 decreases.

【0066】

This reduces the gain (gain) (eg, A1 to A2). At this time, the output ripple component at low temperature becomes strong negative feedback through the capacitor 19, resistor 20, and capacitor 23 and is input to the shunt regulator 24, but the gain is reduced (A2), so the phase characteristics are Since Q1 becomes Q2, the effect is small. That is, the output ripple that increased at low temperature is suppressed and does not oscillate.

【0067】

Furthermore, the output ripple decreases at high temperatures. In addition, the resistance value of the thermistor 33 decreases, and the current to the output terminal (cathode) of the shunt regulator 24 increases, so that the gain increases (for example, A1 to A4 in FIG. 2). At this time, the output ripple component at high temperature becomes a strong negative feedback through the capacitor 19, the resistor 20, and the capacitor 23 and is input to the shunt regulator 24. However, the output ripple is reduced and sufficient phase compensation is provided. Therefore, the effect is small.

【0068】

Further, in FIG. 3B, the light emitting element 7a, the resistor 22, and the shunt regulator 24 are connected in series, and the series circuit including the capacitor 35 and the thermistor 33 is connected in parallel to the resistor 22. Further, a capacitor 23 is provided between the output terminal and the input terminal of the shunt regulator 24.

【0069】

Also in the output side voltage control circuit shown in FIG. 3 (b), when the ESR of the electrolytic capacitor 13 increases and the ripple component increases at low temperature, the resistance value of the thermistor 33 increases, and the resistance 22 and the thermistor 33 become The parallel resistance value increases. That is, the current to the shunt regulator 24 is reduced.

【0070】

Further, at a high temperature, when the ESR of the electrolytic capacitor 13 decreases and the ripple component decreases, the parallel resistance value of the resistor 22 and the thermistor 33 decreases, and the current to the shunt regulator 24 increases.

【0071】

That is, the output-side voltage control circuit of FIG. 3 (b) uses the thermistor 33 to reduce the current when the ripple component at low temperature increases, and conversely increase the current when the ripple component at high temperature decreases. By doing so, the gain is always constant.

【0072】

<Embodiment 2> The second embodiment has a phase compensation circuit on the input side that reduces the ripple component due to the fluctuation of the ESR of the control IC power supply capacitor 3 due to the temperature fluctuation (low temperature, high temperature).

【0073】

FIG. 4 is a schematic configuration diagram of the switching power supply of the second embodiment. In this embodiment, the phase compensation circuit on the primary side will be emphasized and described.

【0074】

As shown in FIG. 4, the input-side phase compensation circuit 37 is connected in parallel to the phototransistor 7b connected to the control unit 4, and the phase correction capacitor 37a (resistance value RX1) is connected to the FB terminal of the control unit 4. A series circuit consisting of a resistor 37b (resistance value RX2> resistor value RX1) is connected, and one of the resistors 37c is connected to the connection point of this series circuit.

【0075】

The capacitance value of the phase correction capacitor 37a is Cx, the resistance value of the resistor 37b is RX1, and the resistance value of the resistor 37c is RX2. These values are also called phase correction constants.

【0076】

Further, a phase constant changing circuit 38 is connected to the input side phase compensation circuit 37. In this phase constant changing circuit 38, the switching element Q1 is connected in parallel to the resistor 37b via the resistor 37c of the input side phase compensation circuit 37.

【0077】

A switching element Q2 is connected to the gate of the switching element Q1 via a thermistor 41, and a resistor 40, a resistor 42, and a resistor 43 are connected in series. Further, the voltage dividing point between the resistor 42 and the resistor 43 is connected to the gate of the switching element Q2.

【0078】

That is, the phase constant changing circuit 38 turns the switching element Q2 on and off with the voltage dividing value Vg2 of the resistor 42 (resistance value R2) and the resistor 43 (resistance value R3), and divides the resistor 40 (resistance value R4) and the thermistor 41. The switching element Q1 is turned on and off at the pressure value Vg1.

【0079】

That is, the gate voltage Vg1 of the switching element Q1 is [Number 1]

<img file="JP2002136123A_D0001.tif" />Indicated by.

【0080】

The above-mentioned phase constant changing circuit 38 and the input side phase compensation circuit 37 are collectively referred to simply as a phase correction unit.

【0081】

The operation of the switching power supply of the second embodiment configured as described above will be described below.

【0082】

(Operation at low temperature) When the temperature is low, the ESR of the electrolytic capacitor increases, the ripple component increases, and the resistance value of the thermistor 41 increases.

【0083】

In other words [Number 2]

<img file="JP2002136123A_D0002.tif" />It becomes the relationship of.

【0084】

As a result, the switching element Q1 is turned on, the resistance component of the CR filter constituting the input side phase compensation circuit 37 becomes a parallel circuit with the resistor 37c and the resistor 37b, and the combined resistance thereof is as shown in FIG. [Number 3]

<img file="JP2002136123A_D0003.tif" />Will be.

【0085】

That is, under this condition, Q1 is turned on and the resistance value of the phase correction constant shifts to the combined resistance value RX1 × RX2 / RX1 + RX2 of RX1 and RX2.

【0086】

That is, even if the output has an increase in the ripple component due to the increase in ESR, the resistance component of the input side phase compensation circuit 37 connected in parallel to the phototransistor 7b increases, so that the amount of phase advance is suppressed. It will keep the circuit stable.

【0087】

(Operation at high temperature) When the temperature is high, the ESR of the electrolytic capacitor decreases, the ripple component decreases, and the resistance value of the thermistor 41 decreases.

【0088】

That is, the switching element Q1 is turned on, and the resistance component of the CR filter constituting the input-side phase compensation circuit 37 is reduced as shown in FIG.

【0089】

As a result, when the ripple component is reduced, the resistance component of the input side phase compensation circuit 37 connected in parallel to the phototransistor 7b is reduced, so that the phase lead amount is increased and the circuit is kept stable. .. That is, it is prevented that the phase lead amount is reduced by reducing the ripple.

【0090】

That is, in the switching power supply of FIG. 4, the phase correction constant range of the control circuit is stabilized for each of high temperature and low temperature by switching the resistance value of the phase correction constant.

【0091】

As shown in FIG. 5, when the ambient temperature is low, the resistance component of the input side phase compensation circuit 37 is reduced to suppress the phase advance, and when the temperature rises, the input side phase compensation circuit 37 By increasing the resistance component and increasing the amount of phase lead, the circuit is always operated stably.

【0092】

Further, in the second embodiment, the resistance component of the input side phase compensation circuit is set to low resistance at low temperature, but conversely, when the resistance component of the input side phase compensation circuit is set to high resistance at low temperature, FIG. 6 shows. As shown, the capacitor 37a, the resistor 37b and the thermistor 41 are connected in series.

【0093】

That is, as shown in FIG. 7, when the temperature is low, the resistance value of the phase compensation circuit is set to be high, and conversely, when the temperature is high, the resistance value is set to be low.

【0094】

&lt;Other Embodiments&gt; Further, as the temperature sensitive element, not only a thermistor having a negative resistance value change characteristic with respect to temperature but also a thermistor (positor) having a positive temperature characteristic can be used. In addition to the circuit examples given here, various application circuits are possible, but in this embodiment, only representative examples are shown.

【0095】

For example, as shown in FIG. 8 (a), a circuit connected in series with the resistor 37c and the positor Po is connected in parallel with the resistor 37b, and when the environmental temperature is low as shown in FIG. 8 (b), Set the value p1 to decrease the resistance value, and conversely set the value p2 to increase the resistance value when the temperature is high.

【0096】

Further, when the characteristics of the input side phase compensation circuit are switched by the switching elements Q1 and Q2, when a positor is used, as shown in FIG. 9 (a), the location of the resistor 40 constituting the phase correction unit. Insert the Posistar Po into.

【0097】

In this way, as shown in (b) of FIG. 9, the amount of change in the resistance component of the phase compensation circuit between low temperature and high temperature becomes a low value at low temperature and a high value at high temperature, but the change amount. Becomes gradual.

【0098】

Further, as shown in FIG. 10A, the positor Po and the resistor 43 may be connected in series, and this voltage dividing point may be connected to the gate of the switching element Q1. In this way, the gate potential changes due to the change in the positor Po. Therefore, as shown in FIG. 10 (b), the amount of change in the resistance component of the phase compensation circuit at low temperature and high temperature becomes a low value at low temperature. , The value becomes high at high temperature, but the amount of change becomes gradual.

【0099】

Further, as shown in FIG. 11A, the thermistor TH having a negative temperature coefficient and the resistor R1 may be connected in series, and this voltage dividing point may be connected to the gate of the switching element Q1. In this way, the gate potential changes due to the change in the thermistor TH. Therefore, as shown in FIG. 11 (b), the amount of change in the resistance component of the phase compensation circuit at low temperature and high temperature becomes a low value at low temperature. , The value becomes high at high temperature, but the amount of change becomes gradual.

【0100】

Further, the thermistor TH having a negative temperature coefficient may be connected in series to the electrolytic capacitor 3, and the voltage dividing point between the thermistor TH and the resistor 42 may be connected to the switching element Q1. In this way, the gate potential changes due to the change in the thermistor TH. Therefore, as shown in FIG. 11 (b), the amount of change in the resistance component of the phase compensation circuit at low temperature and high temperature becomes a high value at low temperature. , The value becomes low at high temperature, but the amount of change becomes gradual.

【0101】

Although each of the above embodiments has been described as a phase compensation circuit having a thermistor on either the input side or the output side, the phase compensation circuit having the thermistor on the input side is provided and the thermistor is provided on the output side. It may be configured to have a provided phase compensation circuit. For example, the output side is the phase compensation circuit shown in FIG. 1, and the input side is the phase compensation circuit shown in FIG. Of course, it is not limited to the phase compensation circuit of FIG. 4, and may be the phase compensation circuit of FIGS. 9, 10, 11, and 12.

【0102】

[Effect of the invention]

As described above, in the present invention, since the resistance value of the temperature sensitive element changes depending on the environmental temperature (low temperature, high temperature), the phase advance of the ripple component due to the electrolytic capacitor is suppressed at low temperature (gain decrease), and the phase at high temperature. The progress of is increased (gain is increased).

【0103】

Therefore, the phase correction constant on the high temperature side or the phase correction constant on the low temperature side is automatically set to the best value, so that a stable switching power supply without oscillation can be obtained in a wide temperature range even if an electrolytic capacitor is used. The effect of being able to do it has been obtained.

【0104】

Further, the present invention utilizes the fact that the output value control circuit on the secondary side (output side) is provided with a phase correction means having a temperature sensitive element, and the resistance value of the temperature sensitive element changes according to the environmental temperature. By doing so, the optimum phase compensation is performed for the ripple component contained in the smooth output.

【0105】

Therefore, on the output side (secondary side), the phase advance is suppressed (gain decrease) at low temperature and the phase advance is increased (gain increase) at high temperature, so that the deeper optimum phase is obtained at low temperature and high temperature. The effect of compensation is obtained.

【0106】

Further, the present invention provides a phase correction means having a temperature sensitive element in the phase correction unit on the input side (primary side), and utilizes the fact that the resistance value of the temperature sensitive element changes according to the ambient temperature. On the primary side, the phase advance is suppressed (gain decrease) at low temperature, and the phase advance is increased (gain increase) at high temperature.

【0107】

That is, on the input side (primary side), the effect that optimum phase compensation is performed at low temperature and high temperature is obtained.

[Simple explanation of drawings]

[Figure 1]

FIG. 5 is a schematic configuration diagram of a switching power supply device with a ripple removing function in consideration of the temperature of the first embodiment.

[Figure 2]

It is a conceptual characteristic diagram of a phase compensation circuit.

[Fig. 3]

It is a schematic block diagram which shows the application example of Embodiment 1.

[Fig. 4]

FIG. 5 is a schematic configuration diagram of a switching power supply device with a ripple removing function in consideration of the temperature of the second embodiment.

[Fig. 5]

It is a characteristic diagram of the phase correction part of Embodiment 2.

[Fig. 6]

It is a schematic block diagram which shows the application example of Embodiment 2.

[Fig. 7]

It is a characteristic diagram of the application example of Embodiment 2.

[Fig. 8]

It is explanatory drawing of the other embodiment.

[Fig. 9]

It is explanatory drawing of the other embodiment.

[Fig. 10]

It is explanatory drawing of the other embodiment.

[Fig. 11]

It is explanatory drawing of the other embodiment.

[Fig. 12]

It is explanatory drawing of the other embodiment.

[Fig. 13]

It is a schematic block diagram of the conventional switching power supply.

[Fig. 14]

It is an ESR characteristic diagram of an electrolytic capacitor.

[Explanation of symbols]

1 DC power supply 2 Start resistance 3 Power supply capacitor for control IC 4 Control IC 5,6 switching element 7a light emitting element 13 Electrolytic capacitor 22 resistance 24 Shant Regulator 31 Output side voltage control circuit 32 Phase compensation circuit with temperature compensation 33 Thermistor