Embodiment
Further specify the utility model in conjunction with the accompanying drawings and embodiments, as shown in Figure 3, the output of the output voltage controller of Switching Power Supply of the present utility model and output current controller is connected to the integral amplifier circuit.
Described integral amplifier circuit also has resistance R 10, K switch 1 to form by integrated operational amplifier JC4 (LM741) and integrating capacitor C6 and negative feedback resistor R7, end of oppisite phase resistance R 8, in-phase end resistance R 9; After integrating capacitor C6 and the negative feedback resistor R7 parallel connection, be connected to 2 pin and 6 pin of integrated operational amplifier JC4 (LM741) respectively, one of end of oppisite phase resistance R 8 is connected to 2 pin of integrated operational amplifier JC4 (LM741), the other end is connected to resistance R 10 and K switch 1, the other end ground connection of resistance R 10, the effect of resistance R 10 is that making end of oppisite phase 2 pin of JC4 is ground level when K switch 1 open circuit.The other end of K switch 1 is connected to accessory power supply-15V, and K switch 1 links with power supply start switch, and one of in-phase end resistance R 9 is connected to 3 pin of integrated operational amplifier JC4 (LM741), other end ground connection.6 pin of integrated operational amplifier JC4 (LM741) are connected to 1 pin of resistance R 4 of the output of output voltage controller JC1 and output current controller JC2.
The circuit of existing Switching Power Supply as can be seen from Figure 1, has switch power supply route resistance R 1, R2, R3 now as shown in Figure 1, potentiometer W1, and integrated operational amplifier JC1 and diode D1 constitute output voltage controller.R3, W1 and accessory power supply+15V constitutes the reference voltage of output voltage.R3 and W1 connect, and the formed electric current of accessory power supply+15V is in series into ground through R3 and W1, and its dividing point is connected to in-phase end 3 pin of JC1, constitute the reference voltage of output voltage.Because the resistance of W1 is from 0 continuously adjustable to nominal value, thereby the reference voltage of output voltage also is continuously adjustable to set point from 0.The anode Uo+ of R1 and R2 and electric power output voltage constitutes voltage sample circuit.R1 and R2 connect, and the formed electric current of output voltage U o+ is gone into ground through R1 and R2, and its dividing point is connected to end of oppisite phase 2 pin of JC1, constitute the output voltage sampling.Output voltage sampling and electric power output voltage constitute certain proportionate relationship.
Constitute the output current controller by diode D2, operational amplifier JC2, resistance R 5 and potentiometer W2, current sampling resistor Ro.R5 and W2 and accessory power supply-15V constitute the reference voltage of output current, and R5 and W2 connect, and the formed electric current of accessory power supply-15V is in series and goes into ground through R5 and W2.Its dividing point is connected to end of oppisite phase 2 pin of JC2, constitutes the reference voltage of output current.Because the resistance of W2 is from 0 continuously adjustable to nominal value, thereby the reference voltage of output current also is continuously adjustable to set point from 0.In-phase end 3 pin of JC2 are connected to 1 pin of current sampling resistor Ro in the power supply major loop, constitute the output current sampling.Output current sampling and electric power outputting current constitute certain proportionate relationship.
1 pin of resistance R 4 meets accessory power supply+15V, and its 2 pin links to each other with the positive pole of D1, D2 and 2 pin of JC3.
Its model of integrated circuit JC3 is SG3525, is the special-purpose control integrated circuit of a Switching Power Supply.Its pin major function is: 2 pin are in-phase end, and general 2 pin are signal input end, are connected to 2 pin of R4 and the positive pole of D1, D2.8 pin are the soft start control end, are connected to the end of capacitor C1, the other end ground connection of C1, and the capacity value of C1 is about 1 microfarad.11 pin and 14 pin respectively output phase different and two identical rectangular pulses of width, these two pulses are called outA and outB.13 pin of JC3 link to each other with 15 pin, meet accessory power supply+15V, 3 pin of JC3 and 12 pin ground connection.10 pin are locked end, when 10 pin are high level, and the JC3 operate as normal, when 10 pin were low level, outA and outB pulse were closed.6 pin are by resistance R 6 ground connection, and 5 pin are by C3 ground connection, and the product of R6 and C3 determines the cycle period of outA and outB.1 pin is an inverting input, and 9 pin are compensation end, generally 1 pin is linked to each other with 9 pin and passes through capacitor C2 ground connection.The operation principle of JC3 is, two rectangular pulses that 1 pin and 14 human hair combing wastes go out, their cycle is subjected to the control of the product of resistance R 6 and capacitor C 3, their width is subjected to the control of the level of 2 pin and 8 pin, when 2 pin and the wherein any one level of 8 pin are zero, outA and outB turn-off simultaneously, and when 2 pin and 8 pin level all were high level, the pulse duration of outA, outB reached the wideest.Usually 8 pin suppose that as soft start 2 pin as start moment JC3 are high level, and 2 pin have just lost the control to the pulse duration of outA, outB.Start moment is because the effect of the absorption electric charge of C1, the voltage of 8 pin is almost nil, this moment, the pulse duration of outA, outB was also almost nil, along with having a small electric current, 8 pin charge to C1, the voltage of C1 is that the voltage on 8 pin can progressively raise, this moment, the pulse duration of outA, outB also progressively broadened thereupon, when 8 pin voltages rise near accessory power supply voltage+15V, the pulse duration of outA, outB also becomes the wideest, this just means the end of the soft start function of 8 pin, and the pulse duration of outA and outB is controlled by the level of 2 pin fully afterwards.
The effect of pulse transformer B1 and B2 is respectively outA and outB pulse to be become two groups, outA1, outA2 and outB1, outB2.Phase place and the width of outA1, outA2 and outA are identical, and phase place and the width of outB1, outB2 and outB are identical.The purpose of this conversion mainly is in order to adapt to the driving main circuit of full-bridge type.The phase relation of outA and outB is seen shown in Figure 2.
The drive circuit of full-bridge type is mainly by large power triode T1, T2, T3, T4, input main power source Vd, capacitance C4, the elementary winding of high frequency main transformer B3 is formed, driving pulse outA1 and outA2 drive T1 and T4 large power triode respectively, and outB1 and outB2 drive T2 and T3 large power triode respectively.Its operation principle is: when driving pulse outA1 and outA2 occur, T1 and T4 conducting simultaneously, T2 and T3 close simultaneously, the formed electric current of elementary main power source Vd will pass through T1, and enter the lower end of the primary coil of B3 by the coupling of capacitor C 4, and then the upper end of inflow primary coil, enter the collector electrode of T4 and form current circuit with going into by the emitter of T4.Because the saturation voltage drop of T1, T4 is very low and capacitor C 4 on charging voltage very low, therefore can be similar to and think, between action period, the voltage of power supply Vd can add on the primary coil of main transformer B3 approx at outA1 and outA2, direction be just going up down negative.In like manner, when outB1 and outB2 driving pulse between action period, pliotron T2, T3 conducting simultaneously, T1 and T4 close simultaneously, and Vd voltage is added on the primary coil of B3, and its direction is negative just down on being.When outA and outB alternating action, it is opposite the width equal direction alternately to occur on the primary coil of B3, and voltage is the pulse voltage of Vd.At this moment on the secondary coil of B3, also can be coupled out the square-wave pulse of direction alternate.Secondary major loop is by the secondary coil of B3, its centre cap ground connection, and form full-wave rectifying circuit by diode D5 and D6, form filter circuit by inductance L 1 and capacitor C 5.RL is a load resistance.Ro is a current sampling resistor.Power-terminal Uo-ground connection.Operation principle is: when occurring the square-wave voltage of alternating polarity variation in the B3 secondary coil, full-wave rectification effect by D5, D6, and through the filter action of L1, C5, become comparatively level and smooth direct current, and through the sub-Uo+ of power positive end, load resistance RL flows into power-terminal Uo-, and through current sampling resistor Ro, finally flows into the centre cap of B3 secondary coil and forms the secondary current major loop.
The voltage stabilizing control assembly is mainly carried out by JC1, and the current stabilization control assembly is mainly carried out by JC2.Voltage stabilizing control assembly and current stabilization control assembly are alternations, when power supply is in voltage stabilizing work, and the 6 pin level step-downs of JC1, the control to electric power output voltage is carried out in diode D1 conducting.This moment, the 6 pin level of JC2 rose to+15V, and diode D2 ends, and does not carry out the control to electric power output voltage.Otherwise when power supply is in current stabilization work, the 6 pin level step-downs of JC2, the control to electric power outputting current is carried out in diode D2 conducting.This moment, the 6 pin level of JC1 rose to+15V, and diode D1 ends, and does not carry out the control to electric power outputting current.
Power supply voltage stabilizing work principle is: when transferring reference voltage of W1 setting, this moment, power supply should have a definite output voltage corresponding with it.Output voltage forms sampling voltage through voltage sample circuit, if sampling voltage is higher than reference voltage, be that the 2 pin voltages of JC1 are when being higher than 3 pin voltages, illustrate that electric power output voltage is higher, at this moment the 6 pin level of JC1 meeting step-down absorbs the electric current that is flow down through R4 by accessory power supply+15V through diode D1, finally makes the 2 pin level step-downs of JC3,11 pin of JC3 and the outA of 14 pin and the pulse duration of outB are narrowed down, finally make the electric power output voltage step-down.Otherwise if sampling voltage is lower than reference voltage, the 6 pin level of JC1 will improve, and make the 2 pin level of JC3 improve, and the pulse duration of outA and outB is broadened, and electric power output voltage is uprised.Like this because the regulating action of JC1, finally make electric power output voltage be stabilized in one with the corresponding definite voltage of reference voltage on.
Power supply current stabilization work principle is: when transferring current reference voltage of W2 setting, when transferring W2, end of oppisite phase 2 pin at JC2 form a definite negative voltage as reference voltage, because in-phase end 3 pin of JC2 are connected to 1 pin of current sampling resistor Ro, when the overcurrent of load resistance RL upper reaches, this electric current promptly flows to the centre cap of transformer secondary output winding by power-terminal Uo-through Ro, and this electric current causes a voltage on Ro, polarity is 2 pin for just, and 1 pin is for negative.Because 2 pin reality link to each other with ground, 1 pin voltage is a negative voltage, this negative voltage links to each other with 3 pin of JC2, if the 2 pin voltages of this voltage ratio JC2 are also low, illustrate that actual current is bigger than constant current set point, at this moment the 6 pin voltages of JC2 are with regard to step-down, finally make the 2 pin voltage step-downs of JC3, this narrows down the pulse duration of outA and outB, finally makes the electric power output voltage step-down, and the electric current that flows through on the RL diminishes.If instead current sampling voltage is higher, it is littler than setting constant current value that actual output current is described, at this moment the 6 pin voltages of JC2 will uprise, and the pulse duration of outA and outB is broadened, and finally makes output current become big.Therefore when transferring current reference voltage of W2 setting, it is corresponding with it that at this moment output current must have a definite current value.
The soft start principle of circuit is: when start moment because 8 pin of JC3 are connected to capacitor C1,8 pin voltages can only slowly rise, even therefore 2 pin voltages are very high, the pulse duration of outA and outB still is subjected to pining down of 8 pin, can not broaden immediately, can only slowly broaden, finally make electric power output voltage slowly rise.
The main effect that soft start function is set is: the moment supply voltage rising that prevents to start shooting is too fast, and the power tube overload is damaged.It is very little to the inhibitory action of power supply start overshoot voltage.As the utility model is not set, overshoot voltage is described at the beginning as this paper, and its overshoot is still between 10%-100%.
Circuit of the present utility model as shown in Figure 3, its operation principle is: when when shutdown, K switch 1 disconnects, this moment because accessory power supply+15V and-15V do not exist, 3 pin of integrated operational amplifier JC4 (LM741), 2 pin, 6 pin are ground level, there is no electric charge on the integrating capacitor C6.The start back is owing to the end of accessory power supply-15V through K switch 1 introducing end of oppisite phase resistance R 8, since in-phase end 3 pin of the termination integrated operational amplifier JC4 of R9, other end ground connection.Operation principle according to integrated operational amplifier, this moment, end of oppisite phase 2 pin also should be ground level, this level will be by end of oppisite phase resistance R 8, K switch 1 forms a constant electric current to-15V, its value is 15V/R8=15V/51K ≈ 0.3mA, the existence of this electric current makes 6 pin level rise from 0V is linear, forms the charging current to integrating capacitor C6, and this charging current should equal 0.3mA.6 pin level are risen to+15V from the slow straight line of 0V of start moment, and just the 1 pin voltage of R4 is not to add immediately+15V voltage after start, but progressively slowly rises to+15V from 0V.This just makes no matter its operating state is how in the short time after start for voltage controller JC1 and current controller JC2, which type of level 6 pin of JC1 and 6 pin of JC2 export, also no matter carry out soft start function JC3 8 pin level how, the 2 pin level of JC3 are slowly risen from 0V, and this is just as the soft start function that power supply has been formed second level.Because 2 pin of JC3 have been increased the soft start function of second level, thereby make the overshoot voltage of high power switching power supply reduce to below 1%, greatly improved the performance of Switching Power Supply by original 10%~100%.
The essential distinction of the utility model and prior art is, in the prior art, owing to starting shooting moment, electric power output voltage or output current are not all set up, be equal to 0, thereby voltage controller can think that output voltage does not reach set point, and the 6 pin voltages of JC1 are increased to maximum, simultaneously current controller thinks that also output current does not reach set point and makes the 6 pin voltages of JC2 be raised to maximum, and the moment of 2 pin after start of the final like this JC3 of making is elevated to maximum immediately.Along with the rising of the 8 pin level of JC3, the pulse duration of outA and outB also increases, in case remove soft start, outA and outB promptly deliver to the power supply major loop with the wideest pulse, make electric power output voltage or output current raise rapidly.Even when reaching the set point of voltage or electric current, but because the hysteresis of voltage sampling and current sampling signal, and there are some inert elements for preventing that power supply from vibrating in the circuit design, this all makes the regulating action of voltage controller or current controller lag behind, even thereby the start moment electric power output voltage or output current reached set point, but the pulse duration of outA or outB can not restrain immediately, thereby makes output voltage or output current that bigger overshoot be arranged.And the utility model is on the basis of the soft start function of 8 pin of JC3, added the soft start function of second level again at 2 pin of JC3, make the pulse duration of outA and outB all not reach the wideest condition in any moment that starts, all the time slowly widen, output voltage also is slowly to increase.When output voltage or output current progressively reached set point, voltage stabilizing control assembly and current stabilization control assembly had enough reaction time restriction outA and the pulse duration of outB, make the overshoot amplitude of output voltage or electric current greatly reduce.