Disclosure of Invention
The technical problem to be solved by the present invention is to provide a multiple output isolated dc power supply, an overload protection circuit thereof and a load regulation compensation circuit thereof, aiming at the defects and shortcomings in the background, which not only can easily realize the expansion of the number of output channels, but also each output has a smaller load regulation, and each output has independent on-off control and overload fault protection functions, and when any output has an overload fault, only the output of the fault path is cut off, thereby ensuring that other paths can continue to operate normally, and having high reliability.
In order to solve the technical problems, the invention specifically adopts the following technical scheme:
a multiple output isolated dc power supply, comprising: the device comprises an isolation power conversion circuit, a multi-path power switch circuit, a multi-path overload protection circuit, a DSP controller, a communication circuit and a load regulation rate compensation circuit; the multi-path power switch circuit comprises a plurality of power switch circuits, the multi-path overload protection circuit comprises a plurality of overload protection circuits, and the plurality of power switch circuits correspond to the plurality of overload protection circuits one to one; the output of the isolation power conversion circuit is used as the input of the load regulation rate compensation circuit, one path of output of the load regulation rate compensation circuit is used as an output voltage sampling signal of the isolation power conversion circuit and is connected to the DSP controller and the communication circuit, a driving signal is obtained after the processing of the DSP controller and is applied to the isolation power conversion circuit, the other path of output of the load regulation rate compensation circuit is used as the input of the multi-path power switch circuit, the DSP controller and the communication circuit receive control signals input from the outside, the control signals are applied to the multi-path power switch circuit after the processing to realize the independent on-off control of the plurality of power switch circuits, the current detection amount of the power switch circuit is respectively input to the corresponding overload protection circuit, and the overload protection control signals output by the overload protection circuit are respectively input to the corresponding power switch.
A multi-channel overload protection circuit is applied to a multi-channel output isolation direct-current power supply, the multi-channel output isolation direct-current power supply comprises a plurality of power switch circuits which are independently controlled to be switched on and off, and the multi-channel overload protection circuit is characterized by comprising a plurality of overload protection circuits, wherein the overload protection circuits correspond to the power switch circuits one by one; the overload protection circuit includes: the output of the over-current delay circuit is input to the over-current comparison circuit, and the outputs of the over-current short-circuit comparison circuit and the over-current comparison circuit are used as overload protection control signals and input to the corresponding power switch circuits.
A load regulation rate compensation circuit is applied to a multi-output isolation direct-current power supply and is characterized by comprising: the output of the isolated power conversion circuit of the direct-current power supply is respectively used as the input of the current detection circuit, the power supply voltage stabilizing circuit, the non-isolated booster circuit and the conditioning circuit, the output of the power supply voltage stabilizing circuit is connected to the power supply end of the current detection circuit, the output of the non-isolated booster circuit is connected to the power supply ends of the conditioning circuit and the reference circuit, and the output of the reference circuit is input into the conditioning circuit; one output of the current detection circuit is input into the conditioning circuit, and the other output of the current detection circuit is used as the input of the multi-path power switch circuit; the output of the conditioning circuit is used as an output voltage sampling signal of the isolation power conversion circuit.
The technical scheme of the invention has the following beneficial effects:
(1) the expansion of the number of power output channels can be easily realized;
(2) no difference between the main road and the auxiliary road exists, and each road has independent on-off control capability;
(3) each path of output has independent overload protection capability, and the overload fault of any path does not influence the normal work of other paths;
(4) the load regulation rate of each output path can be effectively reduced, so that the power supply quality of each output path is consistent;
(5) the method is simple to realize, high in reliability and low in cost.
Detailed Description
Some of the key technologies to which the present invention relates will be described in detail below with reference to the accompanying drawings to support the claims; in order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments.
Example 1
FIG. 1 is a functional block diagram of a multiple output isolated DC power supply; DC input signal VinAfter passing through the isolated power conversion circuit 1, the output signal VoTo the load regulation rate compensation circuit 5, the load regulation rate compensation circuit 5 outputs a signal Vo' to the input of the multi-way power switch circuit 2. The multi-path power switch circuit 2 comprises n power switch circuits, and the rear end of each power switch circuit corresponds to an independent output Vo1~Von. The multi-path overload protection circuit 3 comprises n overload protection circuits, and the overload protection circuits correspond to the power switch circuits one to one. Current detection quantity V of power switch circuits1~VsnInputting a corresponding overload protection circuit, outputting a short-circuit protection signal Vshort1~Vshort5And an overcurrent protection signal Vover1~Vover5And inputting the signals to corresponding power tube switching circuits for overload protection. Each power switch circuit is independently controlled by the DSP controller and control signals CMD 1-n output by the communication circuit 4; the load regulation rate compensation circuit 5 can adjust the output voltage of the converter by detecting the output current of the isolated power conversion circuit 1, so that the load regulation rate of each path of power output is effectively reduced.
FIG. 2 is a schematic block diagram of a multiple output power supply overload protection circuit; taking the first path as an example, the current of the power switch circuitDetecting a voltage drop Vs1The output current is input to an output current detection circuit 6, the output current detection quantity LCS of the output current detection circuit 6 is input to a short-circuit comparison circuit 7 and an over-current delay circuit 8, the output of the over-current delay circuit 8 is input to an over-current comparison circuit 9 after certain delay, and a short-circuit fault protection signal V output by the short-circuit comparison circuitshort1Overcurrent fault protection signal V output by overcurrent comparison circuitover1And the input voltage is input to a corresponding power switch circuit to realize independent overload protection.
Fig. 4 is a specific implementation of the multi-output isolated dc power supply of the present invention, which implements 5 independent outputs based on a half-bridge LLC resonant circuit; the half-bridge LLC resonant circuit is used as an isolated power conversion circuit 1, and the rear end of the half-bridge LLC resonant circuit is connected to 5 paths of independent and same power switch circuits after passing through a load regulation rate compensation circuit 3; fig. 5 is a specific implementation of one of the multiple output power supply overload protection circuits of the present invention, in which overload protection of each output is implemented by an operational amplifier and a comparator and applied to a driving circuit of a power switch circuit.
Taking the first path as an example, the power switch circuit is composed of a current detection resistor Rsense1Power tube S1And corresponding independent driving circuits; an external switch control signal is processed by the DSP controller and the communication circuit 4 and then applied to the 5-path independent drive circuit at the rear stage, so that the independent on-off control of 5-path output is realized; the driving circuits corresponding to the rear stage 5-way power switch circuit are the same and independent from each other, the principle circuit is shown in fig. 5, the driving circuit is composed of a totem pole circuit and an RC feedback circuit, the DSP controller outputs a switch control signal CMD1 to act on an AND gate at the front end of the totem pole to control a power tube S1Wherein the resistance R isup、Rdown、Rg、RfAnd a capacitor CfIs used for determining the size of the power tube S1The switching speed of (1), the detection resistance Rsense1The voltage drop is processed by a proportional amplifier A1 to obtain a current detection value LCS, when the LCS is larger than a reference voltage Ref1, the output is judged to have an overcurrent fault, and at the moment, a capacitor CaDischarging is carried out, the output voltage of the operational amplifier A2 is reduced at a certain rate, and when the output is less than the reference voltage Ref2, the output of the comparator COM1Vover1The high level is changed into the low level and is acted on an AND gate at the front end of the totem pole to control a power tube S1Shutting down, and cutting off overcurrent faults; when the current detection value is larger than the reference voltage Ref3, the output is judged to have short-circuit fault, and the output V of the comparator COM2 at the momentshort1The triode T is controlled to be changed from high level to low level3Is on due to T3One end is connected to the power tube S1The other end of the source electrode passes through a diode D1Is connected to the power tube S1Grid of (2), so T3After the power tube is switched on, the grid source voltage of the power tube is rapidly changed from a negative voltage to a diode conduction voltage, so that the power tube S1Quickly shutting off, and cutting off load short-circuit faults; however, due to the existence of the detection resistor and the on-resistance of the power tube in the subsequent power switch circuit, the output load regulation rate of each path is increased.
FIG. 3 is a schematic block diagram of a load regulation compensation circuit of the present invention that solves the problem of increased load regulation due to a post-stage power switching circuit; firstly, a current detection circuit 10 is connected in series between an isolation power conversion circuit 1 and a multi-path power switch circuit 2, and the current detection circuit 10 adopts an output V of a power supply voltage stabilizing circuit 14c1Supplying power, detecting the output current of the converter and converting into voltage VhDetecting the current by the quantity VhConnected as input to a conditioning circuit 13, the conditioning circuit 13 being supplied by the output V of the non-isolated booster circuit 11c2To supply power, Vc2Need to be greater than VoReference circuit 12 generates a fixed reference voltage VxConnected as an input to a conditioning circuit 13 which outputs a compensation voltage VsenseAs an output voltage sample value of the isolated power conversion circuit 1; when the load current of the power output end is increased, if the load regulation rate compensation is not carried out, the output voltage V of the prior stage is consideredoThe voltage is basically kept unchanged under the voltage stabilization control, and at the moment, the load voltage is reduced because a certain resistance exists between the preceding stage isolation power conversion circuit 1 and the load, including a current detection resistor, a power tube conduction resistor, a wiring resistor and the like; when the load regulation rate compensation circuit is in operation, if the output load current of a certain path is increased, the load regulation rate compensation circuit is in operationOutput voltage V of conditioning circuitsenseThe output voltage of the isolation power conversion circuit 1 is adjusted to be increased, if the voltage increase just compensates the change of the load voltage of the path, the load voltage of the path is basically unchanged, and the load regulation rate of each path of output is effectively reduced.
FIG. 6 is a specific implementation of the multiple output isolated DC power supply load regulation compensation circuit of the present invention; as shown in FIG. 6, the linear regulator U2 (model number LP2950 is used in the figure), the capacitor C1And C2Form a voltage-stabilizing power supply circuit 14, isolate the output V of the power conversion circuit 1oConnected to a capacitor C1One terminal of the voltage regulator is connected with the input terminal of the linear voltage regulator U2, and the capacitor C1Is grounded, and the output of the linear voltage regulator U2 is connected to the capacitor C2One terminal of (C), a capacitor2The other end of the first and second electrodes is grounded; current detection chip U1 and capacitor C3And a capacitor C4Form a current detection circuit 10 for isolating the output V of the power conversion circuit 1oA current output terminal V of the current detection chip U1 connected to the current input terminal of the current detection chip U1o' connecting multiple power switch circuits 2, U2 with their outputs connected to capacitor C3One terminal of the capacitor (C) is connected with the power supply terminal Vcc and the capacitor C of the current detection chip U13The other end of the current detection chip U1 is grounded, and the filter termination capacitor C of the current detection chip U14One terminal of (C), a capacitor4The other end of the current detection chip U1 is grounded, and the detection output V of the current detection chip U1hAs an input to the conditioning circuit 13; a non-isolated boost chip U3 (model number is ADP1612ARMZ-R7 in the figure), a capacitor C5Capacitor C6Resistance R8Resistance R9Resistance R10Inductance L1And a diode D2Form a non-isolated booster circuit 11, isolate the output V of the power conversion circuit 1oThe input end of the non-isolated boost chip U3 is connected with the inductor L1One terminal of (1), inductance L1Another terminal of the U3 is connected with the SW terminal and the diode D2Positive electrode of (2), capacitor C5Is connected to the SS terminal of U3, and a capacitor C5The other end of (3) is grounded, and a resistor R8Is connected to COMP terminal of U3, and a resistor R8Another terminal of the capacitor C6One terminal of (C), a capacitor6Is grounded at the other endResistance R9One terminal of the resistor is connected with the FB terminal of the U3 and the resistor R10One terminal of (1), resistance R9The other end of (3) is grounded, and a resistor R10Another end of the diode D2Negative electrode of (2), diode D2The negative pole of the reference circuit is connected to the positive power supply end of the conditioning circuit 8 and the power supply end of the reference circuit 12; a voltage reference chip U4 (model LM236H-2.5 is selected in the figure), a resistor R5Resistance R6Resistance R7Capacitor C7Diode D3And a diode D4Constituting a reference circuit 12, a resistor R5Is connected to a diode D2Negative electrode of (2), resistance R5Is connected with the other end of the capacitor C7One terminal of (1), diode D3Positive electrode of the voltage reference chip U4, and (+) terminal of the voltage reference chip U4, capacitor C7Is grounded to the (-) terminal of the voltage reference chip U4, and a diode D3Negative pole of (2) is connected with R6One end of (A) R6And the other end of the voltage reference chip U4 is connected with the ADJ end and the R end of the voltage reference chip U47One end of (A) R7Another end of the diode D4Anode of (2), diode D4The negative electrode of (2) is grounded; operational amplifier U5, resistor R1Resistance R2Resistance R3And a resistance R4The detection output end of the current detection chip U1 is connected with the resistor R to form the conditioning circuit 131One terminal of (1), resistance R1The other end of the resistor is connected with the negative end input of the operational amplifier U5 and a resistor R2One terminal of (1), resistance R2The other end of the isolating power conversion circuit 1 is connected with the output end of the operational amplifier U5, and the output end of the isolating power conversion circuit 1 is connected with the resistor R4One terminal of (1), resistance R4The other end of the resistor is connected with the positive end input of the operational amplifier U5 and a resistor R3One terminal of (1), resistance R3And the other end thereof is connected to a (+) end of a reference U4, and the output of the operational amplifier U5 is used as the output voltage of the load regulation compensation circuit 5, that is, the output voltage sampling signal of the preceding stage isolation power conversion circuit.
The compensation principle of the load regulation rate compensation circuit is as follows:
output voltage V of current detection circuit
hCan be expressed as
Where k is the current detection accuracy, I
oIf the equivalent resistance of the output of the isolated power conversion circuit to each load is about R for the output current of the preceding stage isolated power conversion circuit
allThen the first output voltage V
o1Can be expressed as (V)
o-R
allV
h/k+R
allV
c1/2k) and the conditioning circuit output voltage V
senseCan be expressed as
V is set by the design of circuit parameters
o1And V
senseV in the expression
o、V
hAnd V
xIf the coefficients are equal, the output voltage V of the conditioning circuit is
senseIs the same as the variation of the actual load voltage due to the variation of the load current, the output voltage stabilization control of the preceding stage isolation power conversion circuit can realize V
senseNamely, the load voltage of each path is constant.
The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modifications made on the basis of the technical scheme according to the technical idea of the present invention fall within the protection scope of the present invention.