A high-efficiency, low-cross-regulation multi-output power supply

Abstract

The present invention discloses a high-efficiency, low-cross-regulation multi-channel output power supply, belonging to the technical field of power generation, transformation, or distribution. The multi-channel output power supply includes: an auxiliary source circuit, an input protection circuit, a flyback DC / DC multi-channel output circuit, a synchronous rectification and output regulation circuit, and a control loop. The synchronous rectification and output regulation circuit includes two common-source connected MOS transistors that replace the secondary-side rectifier diodes of the flyback DC / DC multi-channel output circuit, and a drive circuit. The drive circuit performs logical AND control on the modulation results of the PWM signal and the regulation results of the sampling signal of a DC voltage signal output by the flyback DC / DC multi-channel output circuit, and outputs the drive signals of the two MOS transistors. By using a drive circuit with fewer components and a simple structure, the transmission efficiency of the multi-channel output power supply is improved and the cross-regulation rate of the multi-channel output voltage is improved.

Description

Technical Field

[0001] The present invention relates to switching power supply technology, and in particular discloses a multi-channel output power supply with high efficiency and low cross-regulation rate, belonging to the technical field of power generation, power transformation or power distribution. Background Art

[0002] In recent years, with the advancement of science and technology and the development of society, an increasing number of electronic products have been developed and used to meet people's yearning for a better life. For the entire electronic circuit system, the stability of the power supply for each module is undoubtedly extremely important. An unstable power supply voltage can cause the circuit to malfunction or, in severe cases, damage the circuit. The entire electronic circuit system requires more than a single power supply voltage; different functional modules require different voltage values. For example, the common STM32F series microcontrollers and TMS320F28 series DSPs require a 3.3V power supply, op amp chips typically require a 5V power supply, and relays require a 12V or 15V power supply. Consequently, multi-output power supplies have attracted widespread attention in this context, with an increasing number of scholars devoting themselves to this field, and multi-output power supplies have experienced rapid development.

[0003] Flyback converter circuits are widely used in multi-output power supplies due to their simple topology, electrical isolation between input and output, wide step-up / step-down voltage range, and ease of achieving a variety of output voltages. In a flyback converter, the transformer performs both inductance and voltage transformation. However, this transformer has significant leakage inductance, which increases energy losses during transmission. Furthermore, the secondary-side rectifier diodes also experience power losses during operation, which are particularly severe when the output voltage is low and the current is high. These two factors contribute to relatively low energy transfer efficiency compared to traditional circuits such as buck and boost converters. Another equally important technical specification for multi-output power supplies is cross-regulation. Typically, when the main control output is loaded, the output voltage of the unloaded or lightly loaded output circuits increases. The degree of this output voltage increase varies with the load on the main control output. Simply put, this is the cross-regulation issue for multi-output power supplies. There are many solutions to the cross-regulation problem of multi-output power supplies. For example, some scholars use pulse width modulation and pulse width delay technology to control the designed three-output DC converter. The cross-regulation rate of the circuit is effectively reduced and the transmission efficiency is also improved to a certain extent. However, the circuit structure adopted by this solution is obtained by integrating two multi-output power supplies. It has two transformers and eight diodes. It has many components, a large size, and a relatively complex control method. In addition, there is still much room for improvement in the power transmission efficiency.

[0004] In summary, the present invention aims to provide a solution that can improve the efficiency of a multi-output power supply and reduce the cross-regulation rate. Summary of the Invention

[0005] The object of the present invention is to address the deficiencies of the above-mentioned background technology and provide a multi-output power supply with high transmission efficiency and low cross-regulation rate. A synchronous rectification and output regulation circuit is connected to each output of the multi-output DC / DC power supply based on a flyback topology structure, and the output voltage is secondary adjusted by the synchronous rectification and output regulation circuit. At the same time, the freewheeling diode on the secondary side of the multi-output DC / DC power supply is replaced with a low-loss MOS transistor, thereby reducing output loss and improving the cross-regulation rate of the multi-output power supply. The technical problems of the existing multi-output power supply cross-regulation rate optimization scheme having many circuit components and complex control are solved, and the invention purpose of reducing the cross-regulation rate and improving the efficiency of the multi-output power supply is achieved by using fewer components and a simple control method.

[0006] The present invention adopts the following technical solutions to achieve the above-mentioned purpose:

[0007] A high-efficiency, low-cross-regulation multi-channel output power supply comprises an auxiliary source circuit, an input protection circuit, a Flyback DC / DC multi-channel output circuit, a synchronous rectification and output regulation circuit, and a control loop.

[0008] The input end of the auxiliary power circuit is connected to a DC input source, and the DC voltage of the primary side input is coupled through the secondary winding of the transformer to output a 15V DC auxiliary power supply. The 15V DC is converted into a 5V DC auxiliary power supply through a three-terminal voltage regulator connected to the 15V DC output end. The 15V DC auxiliary power supply is used to power the input protection circuit, Flyback DC / DC multi-output circuit, and control circuit. The 5V DC auxiliary power supply is used to power the input protection circuit, synchronous rectification and output regulation circuit.

[0009] The input protection circuit's input is connected to a DC input source. When the DC input voltage is too high, too low, or the DC input current is too high, the circuit disconnects the branch between the DC input source terminal and the Flyback DC / DC multi-output circuit input terminal, limiting the voltage input to the Flyback DC / DC multi-output circuit to an appropriate range. Furthermore, when the input current is high, the input side of the Flyback DC / DC multi-output circuit is protected from power failure.

[0010] The Flyback DC / DC multi-output circuit performs DC / DC conversion on DC power that has passed input under- and over-voltage protection, outputting multiple DC signals. The conduction state of the primary side main switch is determined by the PWM output of the control loop.

[0011] A synchronous rectification and output regulation circuit includes two commonly-sourced MOS transistors that replace the secondary-side rectifier diodes of a flyback DC / DC multi-output circuit, and a drive circuit. The drain of one MOS transistor is connected to the inductor voltage of the secondary winding of the flyback DC / DC multi-output circuit, and the drain of the other MOS transistor is the output end of a DC signal. The drive circuit performs logical AND control on the modulation result of the PWM signal and the regulation result of the sampling signal of a DC voltage signal output by the flyback DC / DC multi-output circuit, and outputs the drive signals for the two MOS transistors.

[0012] The input end of the control loop is connected to the sampling signals of multiple DC signals, and after adjusting the sampling signals, a PWM signal is output to the main switch tube in the Flyback DC / DC multi-channel output circuit.

[0013] Furthermore, in a high-efficiency, low-cross-regulation multi-output power supply, the driving circuit includes:

[0014] A synchronous rectification unit, whose input terminal is connected to the PWM signal output by the control loop, detects the high and low levels of the PWM signal output by the control loop, outputs a low level when the PWM signal output by the control loop is a high level, and outputs a high level when the PWM signal output by the control loop is a low level;

[0015] An output adjustment unit, having an input terminal connected to a sampling signal of a DC voltage signal output by the Flyback DC / DC multi-channel output circuit, adjusts the error between the sampling signal and a reference value, and outputs PWM1 for adjusting a DC signal output by the Flyback DC / DC multi-channel output circuit;

[0016] A logic AND gate, whose input is connected to the output of the synchronous rectifier unit and the output of the output regulation unit, outputs PWM for turning off the two MOS transistors on the secondary side of the Flyback DC / DC multi-channel output circuit when the synchronous rectifier unit outputs a low level, and outputs PWM1 for regulating a DC signal output by the Flyback DC / DC multi-channel output circuit when the synchronous rectifier power supply outputs a high level; and

[0017] The PWM drive unit has an input terminal connected to the output terminal of the logic AND gate, and outputs a drive signal for two MOS tubes on the secondary side of the Flyback DC / DC multi-channel output circuit.

[0018] Furthermore, in a multi-output power supply with high efficiency and low cross-regulation rate, the input protection circuit includes: a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a sixth capacitor, a voltage reference chip, a first comparator, a second comparator, a logic OR gate, a second diode, a transistor, a normally closed relay, and a fuse, wherein the first comparator and the second comparator are powered by a 5V DC auxiliary power supply, one end of the third resistor is connected to a DC input source, the other end of the third resistor, one end of the fourth resistor, one pole of the sixth capacitor, and the anode of the voltage reference chip are all connected to a signal ground, the other pole of the sixth capacitor, the cathode of the voltage reference chip, and the reference end of the voltage reference chip are all connected to the inverting input terminal of the first comparator, one end of the fifth resistor is connected to the DC input source, the other end of the fifth resistor is connected to the cathode of the voltage reference chip, and the sixth capacitor is connected to the inverting input terminal of the first comparator. One end of the resistor is connected to a DC input source, the other end of the sixth resistor and one end of the seventh resistor are both connected to the non-inverting input of the first comparator, the other end of the seventh resistor is connected to signal ground, the non-inverting input of the second comparator is connected to the reference terminal of the voltage reference chip, the inverting input of the second comparator is connected to the short-circuit between the third resistor and the fourth resistor, the output of the first comparator and the output of the second comparator are respectively connected to the input of a logic OR gate, the output of the logic OR gate is connected to one end of an eighth resistor, the other end of the eighth resistor is connected to the base of a transistor, the emitter of the transistor is connected to signal ground, the collector of the transistor is connected to the anode of a second diode, the cathode of the second diode is connected to a 15V DC auxiliary power supply, the energy storage element of a normally closed relay is connected in parallel with the second diode, and a fuse and a knife switch of the normally closed relay are connected in series in a branch between the DC input source access terminal and the input terminal of the Flyback DC / DC multi-channel output circuit.

[0019] Furthermore, in a high-efficiency, low-cross-regulation multi-output power supply, the synchronous rectification unit includes: a third comparator, a fifteenth resistor, a sixteenth resistor, and a seventeenth resistor, wherein the third comparator is powered by a 5V DC auxiliary power supply output by the auxiliary source circuit, one end of the sixteenth resistor is connected to the 5V DC auxiliary power supply, the other end of the sixteenth resistor is connected to one end of the fifteenth resistor, the short-circuit between the sixteenth resistor and the fifteenth resistor is connected to the non-inverting input of the third comparator, the other end of the fifteenth resistor is connected to the signal ground, one end of the seventeenth resistor is connected to the PWM signal output by the control loop, the other end of the seventeenth resistor is connected to the inverting input of the third comparator, the output of the third comparator outputs a signal for turning off two MOS transistors on the secondary side of the Flyback DC / DC multi-output circuit, and the voltage at the short-circuit between the sixteenth resistor and the fifteenth resistor is a threshold voltage for distinguishing high and low levels of the PWM signal output by the control loop.

[0020] Furthermore, in a high-efficiency, low-cross-regulation multi-output power supply, an output adjustment unit includes: an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a twenty-first resistor, a ninth capacitor, a fourth comparator, and a fifth comparator. The fourth and fifth comparators are powered by a 5V DC auxiliary power supply output by the auxiliary source circuit. One end of the nineteenth resistor is connected to a sampling signal of a DC voltage signal output by the Flyback DC / DC multi-output circuit. The other end of the nineteenth resistor is connected to an inverting input of the fifth comparator. One end of the twentieth resistor is connected to the 5V DC auxiliary power supply. The other end of the twentieth resistor is connected to one end of a twenty-first resistor. A shorting point between the twentieth and twenty-first resistors is connected to a non-inverting input of the fifth comparator. The other end of the twenty-first resistor is connected to a signal ground. A branch consisting of the eighteenth resistor and the ninth capacitor in series is connected between the inverting input and output of the fifth comparator. The non-inverting input of the fourth comparator is connected to the output of the fifth comparator. The inverting input of the fourth comparator is connected to a triangular carrier signal. The output of the fourth comparator outputs PWM1 for adjusting the DC signal output by the Flyback DC / DC multi-output circuit.

[0021] Furthermore, in a multi-output power supply with high efficiency and low cross-regulation rate, the triangular carrier signal is generated by a triangular carrier generating unit, and the triangular carrier generating unit includes: a twenty-second resistor, a twenty-third resistor, a twenty-fourth resistor, a sliding rheostat, a tenth capacitor, a transistor, a sixth comparator, and a seventh comparator, wherein the sixth comparator and the seventh comparator are powered by a 5V DC auxiliary power supply output by the auxiliary source circuit, one end of the twenty-third resistor is connected to the 5V DC auxiliary power supply, and the other end of the twenty-third resistor and one end of the twenty-second resistor are short-circuited to the same end of the sixth comparator. The inverting input terminal of the sixth comparator is connected, the other end of the twenty-second resistor is connected to the signal ground, one end of the sliding rheostat is connected to the signal ground, the other end of the sliding rheostat, one electrode of the tenth capacitor, and the emitter of the transistor are all connected to the inverting input terminal of the sixth comparator, the other electrode of the tenth capacitor, the collector of the transistor, and one end of the twenty-fourth resistor are all connected to the output terminal of the sixth comparator, the inverting input terminal of the seventh comparator is connected to the 5V DC auxiliary power supply, the output terminal of the seventh comparator is connected to the base of the transistor, and the non-inverting input terminal of the seventh comparator is connected to the other end of the twenty-fourth resistor as the output terminal of the triangular carrier signal.

[0022] Furthermore, a multi-output power supply with high efficiency and low cross-regulation rate is provided, wherein the resistance value of the fifteenth resistor R15, the resistance value of the sixteenth resistor R16, the resistance value of the twenty-second resistor R22, and the resistance value of the twenty-third resistor R23 satisfy the constraint condition that the threshold voltage is greater than the minimum voltage of the triangular carrier.

[0023] The present invention adopts the above technical solution and has the following beneficial effects:

[0024] (1) The present invention combines synchronous rectification technology with the output-side secondary regulation control concept to propose an innovative solution for reducing the cross-regulation rate. It can not only improve the transmission efficiency through synchronous rectification technology, but also perform secondary regulation on the output voltage to reduce the cross-regulation rate of multi-output power supplies.

[0025] (2) The present invention replaces the rectifier diode on the secondary side of the flyback converter in the multi-output power supply with two MOS tubes connected in common source, thereby avoiding the active power loss of the rectifier diode and quickly driving the two MOS tubes through a simple analog circuit, thereby improving the transmission efficiency of the multi-output power supply.

[0026] (3) The present invention drives an analog circuit for two MOS transistors on the secondary side of a flyback converter in a multi-channel output power supply. The circuit has few components, low cost, simple structure, and is easy to implement. The circuit avoids simultaneous conduction of the MOS transistors on the primary and secondary sides of the flyback converter by real-time detection of the high and low levels of the PWM output of the control loop. The transmission efficiency of the multi-channel output power supply is improved and the cross-regulation rate of the multi-channel output voltage is improved by performing a logical AND operation on the PWM high and low level detection results and the output sampling signal error processing results.

[0027] (4) The present invention also proposes a frequency-adjustable triangular carrier generating unit, which can manually adjust the frequency of the triangular carrier, thereby making the frequency of the secondary adjustment of the multi-channel output voltage adjustable, further improving the transmission efficiency of the multi-channel output power supply.

[0028] (5) The input protection circuit of the multi-output power supply of the present invention can realize under-voltage and over-voltage protection of the input voltage and input over-current protection. The logic operation part can limit the input voltage to a certain range, and the fast-blow fuse can be blown in time when the input current is too large, thereby improving the service life and safety of the power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the overall structure of the multi-output power supply of the present invention.

[0030] Figure 2 This is a circuit diagram of the auxiliary source circuit of the present invention.

[0031] Figure 3 This is a circuit diagram of the input protection circuit of the present invention.

[0032] Figure 4 FIG. 4 is a circuit diagram of a Flyback DC / DC multi-channel output circuit of the present invention.

[0033] Figure 5 This is a circuit diagram of the first synchronous rectification output regulation circuit of the present invention.

[0034] Figure 6This is a circuit diagram of the second synchronous rectification output regulation circuit of the present invention.

[0035] Explanation of the numbers in the figure: Q1, Q3, Q4, Q5, Q7 are the first, third, fourth, fifth, and seventh switching tubes, Q2 and Q6 are transistors, T1~T2 are the first and second transformers, C1~C11 are the first to eleventh capacitors, D1~D2 are the first and second diodes, R1~R30 are the first to thirtieth resistors, Rsr is a sliding rheostat, U1A, U1B, U2A, U2B, U2C, U3A, U3B, U4A, U4B, U4C are the first to tenth comparators, Z1 is a TL431 voltage reference chip, F1 is a fuse, OR1 is a logic OR gate, RY1 is a normally closed relay, and AND1 is a logic AND gate. DETAILED DESCRIPTION

[0036] The technical solution of the invention is described in detail below with reference to the accompanying drawings.

[0037] The high-efficiency and low-cross-regulation multi-output power supply disclosed in the present invention is as follows Figure 1 As shown, the system includes: an auxiliary source circuit, an input protection circuit, a flyback DC / DC multi-output circuit, a first synchronous rectification and output regulation circuit, a second synchronous rectification and output regulation circuit, and a control loop. The DC voltage V1 first passes through the auxiliary source circuit to generate two auxiliary supply voltages of 15V and 5V. V1 is also connected to the input protection circuit, which limits the input voltage Vin of the flyback DC / DC multi-output circuit to a reasonable range. When the DC voltage V1 is too high or too low, the input protection circuit disconnects the input of the flyback DC / DC multi-output circuit. When the input current is too high, the DC voltage V1 input circuit is disconnected, protecting subsequent circuits. After passing through the input protection circuit, the voltage Vin is applied to the input of the flyback flyback converter. This voltage Vin is regulated by the flyback DC-DC multi-output circuit and the closed-loop control loop, and then outputs two DC voltage signals, VL1 and VL2. Each of the two outputs of the flyback DC-DC multi-output circuit is connected to a synchronous rectification and output regulation circuit, which performs synchronous rectification and secondary output voltage regulation. The control signal for the synchronous rectification and output regulation circuit is generated by analog circuitry, which operates on the PWM signal output by the control loop and the sampled signals of the synchronous rectification and output regulation circuit's output voltages, Vo1 and Vo2. When the loads of the two outputs are inconsistent, the output voltage of the lower-loaded output increases. In this case, the synchronous rectification and output voltage regulation circuit regulates the output voltage by controlling the conduction state of the flyback DC-DC multi-output circuit's secondary-side switches, thereby maintaining output voltage stability.

[0038] The auxiliary power circuit converts VI DC into 15V DC and 5V DC. Figure 2 As shown, the two ends of the primary winding of the first transformer T1 are connected to the VI+ terminal and the VI- terminal, respectively. The first switch Q1 is connected in the primary circuit of the first transformer T1. The first diode D1, the third capacitor C3, and the auxiliary winding W2 of the first transformer T1 are connected to form a secondary circuit. The branch formed by the series connection of the first capacitor C1 and the first resistor R1 is connected in parallel between the cathode and anode of the first diode D1. The second capacitor C2 and the third capacitor C3 are connected in parallel. The auxiliary winding W2 of the first transformer T1 generates a 15V auxiliary power supply voltage through coupling with the primary winding W1. The output end of the 15V auxiliary power supply voltage is connected to the input terminal of the three-terminal regulator MC78M05 through the second resistor R2. The ground terminal of the three-terminal regulator MC78M05 is connected to the signal ground GNDS. The fourth capacitor C4 and the fifth capacitor C5 are connected between the output terminal of the three-terminal regulator MC78M05 and the signal ground GNDS. After the 15V voltage passes through the three-terminal regulator MC78M05, a 5V power supply voltage is output. The auxiliary power circuit mainly provides the required 5V and 15V power supply voltages for the power chip LD5535, the three-terminal voltage regulator MC78M05, the operational amplifier chip LM324 and other circuits in the control loop to facilitate stable operation of the circuit.

[0039] The input protection circuit limits the input voltage to an appropriate range. When the input voltage is too high or too low, the relay is controlled by the logic circuit to disconnect the input side circuit of the Flyback DC / DC multi-channel output circuit, thereby achieving the purpose of protecting the entire circuit. Figure 3As shown, the cathode C of the TL431 voltage reference chip Z1 is connected to the input DC voltage VI through the fifth resistor R5, the anode A is grounded, the reference terminal R is short-circuited with the cathode C, and the short-circuit point is connected to the inverting input terminal of the first comparator U1A and the non-inverting input terminal of the second comparator U1B. After the circuit is normally operated, the TL431 voltage reference chip Z1 outputs a 2.5V reference voltage; the input voltage VI is connected to the non-inverting input terminal of the first comparator U1A after being divided by the sixth resistor R6 and the seventh resistor R7. At the same time, the input DC voltage VI is connected to the inverting input terminal of the second comparator U1B after being divided by the third resistor R3 and the fourth resistor R4. The other end of the fourth resistor R4 (relative to the end connected to the third resistor R3) is connected to one electrode of the sixth capacitor C6 and the TL431. 1 voltage reference chip Z1 is connected, and the other electrode of the sixth capacitor C6 is connected to the inverting input terminal of the first comparator U1A; the output terminals of the first comparator U1A and the second comparator U1B are respectively connected to the two input terminals of the logic OR gate OR1, and the output terminal of the logic OR gate is connected to the base set of the transistor Q2 via the eighth resistor R8. The collector of the transistor Q2 is connected to the 15V DC power via the second diode D2. The energy storage element of the normally closed relay RY1 is connected in parallel between the cathode and anode of the second diode D2. The knife switch of the normally closed relay RY1 and the fuse F1 are both connected in series in the line between the DC power VI input terminal and the input terminal of the Flyback DC / DC multi-channel output circuit. When the input voltage VI is too high, the voltage at the non-inverting input of the first comparator U1A increases and exceeds the 2.5V reference voltage at its inverting input. Comparator U1A outputs a high level, and after the logic OR1 operation, the base-collector voltage of transistor Q2 also reaches a high level. Normally closed relay RY1 then conducts, disconnecting the input side of the Flyback DC / DC multi-output circuit. When the input voltage VI is too low, the voltage at the inverting input of the second comparator U1B decreases and falls below the 2.5V reference voltage at its non-inverting input. Comparator U1B outputs a high level, and after the logic OR1 operation, the base-collector voltage of transistor Q2 also reaches a high level. Normally closed relay RY1 then conducts, disconnecting the input side of the Flyback DC / DC multi-output circuit. On the other hand, if the input current is too high, fast-blow fuse F1 will blow. This input protection circuit provides undervoltage, overcurrent, and overcurrent protection for the input of the Flyback DC / DC multi-output circuit.

[0040] The Flyback DC / DC multi-channel output circuit is a DC input. The DC voltage VI is transmitted to the Vin+ input terminal of the Flyback DC / DC multi-channel output circuit after passing through the input protection circuit with input under-voltage and over-voltage protection functions. The DC voltage Vin is converted into voltage between two DC-DC channels through the Flyback flyback converter. Figure 4As shown, the two ends of the primary winding of the second transformer T2 are respectively connected to the Vin+ and Vin- input terminals, the third switching tube is connected to the primary loop of the second transformer, the auxiliary winding W4 of the second transformer and the seventh capacitor C7 form a first secondary loop, the ninth resistor R9, the tenth resistor R10, and the eleventh resistor R11 form a sampling circuit for the first output voltage Vo1, the first synchronous rectification and output regulation circuit consists of a switching tube that replaces the secondary diode in the Flyback topology and a drive signal control module, the auxiliary winding W5 of the second transformer and the eighth capacitor C8 form a second secondary loop, the twelfth resistor R12, the thirteenth resistor R13, and the fourteenth resistor R14 form a sampling circuit for the second output voltage Vo2, and the second synchronous rectification and output regulation circuit consists of a switching tube that replaces the secondary diode in the Flyback topology and a drive circuit.

[0041] The switching power supply control chip in the control loop can be the LD5535 power supply chip, which has built-in protection against overvoltage, overcurrent, and short-circuit faults. The control circuit adjusts the sampled signals of the two output voltages and outputs a set of PWM signals. PWM is used to control the conduction state of switch Q3, thereby achieving the purpose of controlling the output voltage.

[0042] The synchronous rectification and output regulation circuit replaces the diode in the Flyback topology with two MOS switches. The replaced MOS switches are controlled according to the PWM signal output by the control loop and the output voltage sampling signal, thereby achieving high-efficiency energy transmission and secondary regulation of the output voltage.

[0043] The first synchronous rectification and output regulation circuit is as follows Figure 5As shown, the drain D of the fourth switch tube Q4 is connected to the inductor voltage VL1 of the auxiliary winding W4, the source S of the fourth switch tube Q4 is connected to the source S of the fifth switch tube Q5, and the drain D of the fifth switch tube Q5 outputs the first output voltage Vo1. The gates G of the fourth switch tube Q4 and the fifth switch tube Q5 are simultaneously connected to the driving module. The driving module is connected to the driving signal generating module. The driving signal generating unit includes a first synchronous rectification unit, a second output regulation unit, and is connected to the logic gate AND1. The input end of the driving module is connected to the output end of the logic AND gate AND1. The high and low levels of the driving signal are controlled by the output end of the logic AND gate. In the first synchronous rectification unit, 5V is divided in series by the fifteenth resistor R15 and the sixteenth resistor R16 to obtain a threshold voltage Vth1. The threshold voltage Vth1 is connected to the non-inverting input of the third comparator U2A. This threshold voltage Vth1 is used to distinguish between the high and low levels of the PWM control signal of the primary-side switch tube of the flyback converter to prevent the primary and secondary-side switches from being turned on at the same time. The PWM signal output by the control loop is connected to the inverting input of the third comparator U2A through the seventeenth resistor R17. In the first output regulation unit, 5V is connected to the non-inverting input of the fifth comparator U2C after being divided in series by the 20th resistor R20 and the 21st resistor R21. The first output voltage sampling signal V1 is connected to the inverting input of the fifth comparator U2C via the 19th resistor R19. The 18th resistor R18 and the 9th capacitor C9 are connected between the output and inverting input of the fifth comparator U2C to form a PI controller. The output of the fifth comparator U2C is connected to the non-inverting input of the fourth comparator U2B, while the inverting input of the fourth comparator U2B is connected to a triangular carrier. The triangular carrier signal is generated by the triangular carrier generation unit. The outputs of the third comparator U2A and the fourth comparator U2B are connected to the two inputs of the logic AND gate AND1, respectively. 5V is connected to the non-inverting input of the sixth comparator U3A after being divided in series by the twenty-second and twenty-third resistors R22 and R23. The other end of the twenty-second resistor R22 (the end shorted to the twenty-third resistor R23) is connected to the signal ground GNDS. The other end of the twenty-third resistor R23 (the end shorted to the twenty-second resistor R22) is connected to 5V. The inverting input of the sixth comparator U3A is connected to the signal ground GNDS via the sliding rheostat Rsr. Simultaneously, the inverting input of the sixth comparator U3A and the shorting point between the sliding rheostat Rsr are connected to one electrode of the tenth capacitor C10. The other electrode of the tenth capacitor C10 is connected to the output of the sixth comparator U3A. Thus, the sixth comparator U3A forms an integral operation circuit. The output of the sixth comparator U3A is connected to the inverting input of the fourth comparator U2B via the twenty-fourth resistor R24.The sixth switch tube Q6 is connected in parallel with the tenth capacitor C10. The base of the sixth switch tube Q6 is connected to the output end of the seventh comparator U3B. The inverting input end of the seventh comparator U3B is connected to a 5V voltage. The non-inverting input end of the seventh comparator U3B is connected to a triangular carrier. The sixth comparator U3A and the seventh comparator U3B together constitute a triangular carrier generation unit.

[0044] According to the working principle of the triangular carrier generation unit in the synchronous rectification and output regulation circuit, the voltage output by the integration circuit formed by the sixth comparator U3A is: This value is the relationship between the amplitude of the triangular carrier and time. The non-inverting input of the seventh comparator U3B is connected to the output of the sixth comparator U3A, the inverting input of the seventh comparator U3B is connected to a 5V voltage, and the output of the seventh comparator U3B is connected to the base of the transistor Q6. When the triangular carrier output by the sixth comparator U3A reaches 5V, the output of the seventh comparator U3B changes from a low level to a high level, and at the same time the transistor Q6 is turned on, the integration circuit formed by the sixth comparator U3A is reset, the triangular carrier amplitude becomes the minimum value, the output of the seventh comparator U3B changes from a high level to a low level, the transistor Q6 is disconnected, and the integration circuit formed by the sixth comparator U3A works until the output of the sixth comparator U3A reaches 5V again, thus forming a periodic triangular carrier signal. From the above analysis, it can be seen that the maximum value of the triangular carrier is 5V, the minimum value is Va, and Therefore, in order to obtain a triangular carrier with an amplitude of 0.5 as much as possible, the resistance of the twenty-third resistor R23 should be greater than the resistance of the twenty-second resistor R22 by more than one order of magnitude. In addition, to ensure the normal operation of the synchronous rectification and output regulation circuits, the threshold voltage Vth must be greater than the minimum triangular carrier voltage Va. That is, the resistance values of the fifteenth resistor R15, the sixteenth resistor R16, the twenty-second resistor R22, and the twenty-third resistor R23 must satisfy the relationship: In addition, from the above analysis, it can be seen that the triangular carrier increases from the minimum value Va to 5V for one cycle, so the equation can be: Find the switching period of the triangular carrier: Then the switching frequency f of the triangular carrier is: From this, we can see that the triangular carrier's switching frequency f is directly proportional to the twenty-second resistor R22, and inversely proportional to the twenty-third resistor R23, the sliding rheostat Rsr, and the tenth capacitor C10. Therefore, the triangular carrier generation unit can change the triangular carrier's switching frequency by varying the resistance of the sliding rheostat. The triangular carrier's switching frequency is also the operating frequency of the secondary-side regulation unit. When the output regulation unit's operating frequency decreases, the output voltage's accuracy and dynamic performance deteriorate. However, as the operating frequency decreases, the heat loss of the switches Q4 and Q5 decreases, which improves the transmission efficiency of the multi-output power supply. When the output regulation unit's operating frequency increases, the output voltage's accuracy and dynamic performance also improve. However, as the operating frequency increases, the heat loss of the fourth and fifth switches Q4 and Q5 increases, placing higher demands on the circuit's heat dissipation. When the sliding rheostat is moved leftward, the resistance of Rsr increases, and the triangular carrier's switching frequency decreases. When the sliding rheostat is turned to the right, the resistance of Rsr decreases, and the switching frequency of the triangle carrier increases. Therefore, according to the performance requirements of the multi-channel output power supply, the operating frequency of the output adjustment unit can be changed by turning the sliding rheostat to adapt to different working environments.

[0045] During the asynchronous rectification phase (i.e., when PWM is high), the output of the third comparator U2A is low. After performing an AND gate logic operation with the fourth comparator U2B, the output of the AND gate AND1 is low. Therefore, during this asynchronous rectification phase, the fourth and fifth switches Q4 and Q5 remain off. During the synchronous rectification phase (i.e., when PWM is low), the output of the third comparator U2A is high. After performing an AND gate logic operation with the fourth comparator U2B, the output of the AND gate AND1 is determined by the PWM1 signal output by the fourth comparator U2B. Therefore, during the synchronous rectification phase, the conduction state of the fourth and fifth switches Q4 and Q5 is determined solely by the high and low levels of the PWM1 signal. In the synchronous rectification stage, when the first output voltage sampling signal V1 is less than the set value: the reference voltage Vref1 at the non-inverting input terminal of the fifth comparator U2C is greater than the voltage at the inverting input terminal. After the difference between the two is adjusted by the PI controller, the output of the sixth comparator U2C increases. After the output value of the sixth comparator U2C is compared with the triangular carrier at the inverting input terminal of the fourth comparator U2B, the PWM1 control signal output by the fourth comparator U2B becomes high level, the fourth switch tube Q4 and the fifth switch tube Q5 are closed after being driven by PWM Drive, and the first output voltage rises. When the first output voltage sampling value V1 is greater than the set value: the reference voltage Vref1 at the non-inverting input terminal of the fifth comparator U2C is less than the voltage at the inverting input terminal. After the difference between the two is adjusted by the PI controller, the output of the fifth comparator U2C decreases. After the output value of the fifth comparator U2C is compared with the triangular carrier at the inverting input terminal of the fifth comparator U2B, the PWM1 control signal output by the fifth comparator U2B becomes low level. The fourth switch tube Q4 and the fifth switch tube Q5 are disconnected after being driven by PWM Drive, and the first output voltage drops. The second synchronous rectification and output regulation circuit is as follows: Figure 6 As shown, its structure is identical to the first synchronous rectification and output regulation circuit, except that the triangular carrier signal is a triangular carrier signal of a given frequency. Through the aforementioned control method, the synchronous rectification and output regulation circuit can simultaneously achieve the goals of synchronous rectification of multiple output power supplies and secondary output voltage regulation, thereby improving the transmission efficiency of the multiple output power supplies and reducing the cross-regulation rate of the multiple output power supplies.

[0046] The above embodiments are merely exemplary descriptions of the present invention and do not limit its scope of protection. Persons skilled in the art may make partial changes thereto. For example, other circuit modules for detecting PWM high and low levels may be used to implement the functions of the rectifier unit. Other circuit modules for adjusting the error of the output voltage sampling signal of the Flyback DC / DC multi-output circuit may be used to implement the functions of the output adjustment unit. Other circuit modules for adjusting the triangular carrier frequency may be used to implement the functions of the triangular carrier generation unit. Based on actual application requirements, one output voltage of the Flyback DC / DC multi-output circuit may be secondary regulated using a frequency-adjustable triangular carrier, while other output voltages may be secondary regulated using a fixed-frequency triangular carrier. Any equivalent substitution that is consistent with the spirit of the invention falls within the scope of protection of the present invention.

Claims

1. A high-efficiency, low-cross-regulation, multi-output power supply, characterized in that: include: The auxiliary power circuit has an input terminal connected to a DC input source and outputs a 15V DC auxiliary power supply and a 5V DC auxiliary power supply. The 15V DC auxiliary power supply is used to power the input protection circuit, the Flyback DC / DC multi-channel output circuit, and the control circuit. The 5V DC auxiliary power supply is used to power the input protection circuit, the synchronous rectification and the output regulation circuit. The input protection circuit has its input terminal connected to the DC input source. When the DC input voltage is too large, too small, or too high, the circuit between the DC input source terminal and the Flyback DC / DC multi-channel output circuit input terminal is disconnected. Flyback DC / DC multi-channel output circuit performs DC / DC conversion on the input DC power and outputs multiple DC signals. A synchronous rectification and output regulation circuit includes two MOS transistors connected in common source mode to replace the secondary-side rectifier diodes of a Flyback DC / DC multi-channel output circuit, and a drive circuit. The drain of one MOS transistor is connected to the inductor voltage of the secondary winding of the Flyback DC / DC multi-channel output circuit, and the drain of the other MOS transistor is the output end of a DC signal. The drive circuit performs logical AND control on the modulation result of the PWM signal and the adjustment result of the sampling signal of the DC voltage signal output by the Flyback DC / DC multi-channel output circuit, and outputs the drive signals for the two MOS transistors. A control loop, whose input is connected to the sampling signals of multiple DC signals, adjusts the sampling signals and outputs PWM signals to the main switch tubes in the Flyback DC / DC multi-channel output circuit; The driving circuit includes: The synchronous rectification unit has its input connected to the PWM signal output by the control loop, detects the high and low levels of the PWM signal output by the control loop, outputs a low level when the PWM signal output by the control loop is high, and outputs a high level when the PWM signal output by the control loop is low. The output adjustment unit has an input terminal connected to a sampling signal of a DC voltage signal output by the Flyback DC / DC multi-channel output circuit, adjusts the error between the sampling signal and the reference value, and outputs PWM1 for adjusting the DC signal output by the Flyback DC / DC multi-channel output circuit. The logic AND gate has its input connected to the output of the synchronous rectifier unit and the output of the output regulation unit. When the synchronous rectifier unit outputs a low level, it outputs PWM to turn off the two MOS tubes on the secondary side of the Flyback DC / DC multi-channel output circuit. When the synchronous rectifier power supply outputs a high level, it outputs PWM1 for regulating one DC signal output by the Flyback DC / DC multi-channel output circuit. The PWM drive unit has an input terminal connected to the output terminal of the logic AND gate, and outputs a drive signal for two MOS tubes on the secondary side of the Flyback DC / DC multi-channel output circuit.

2. A high-efficiency, low-cross-regulation, multi-output power supply according to claim 1, characterized in that: The input protection circuit includes: a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a sixth capacitor, a voltage reference chip, a first comparator, a second comparator, a logic OR gate, a second diode, a transistor, a normally closed relay, and a fuse, wherein the first comparator and the second comparator are powered by a 5V DC auxiliary power supply, one end of the third resistor is connected to the DC input source, the other end of the third resistor is connected to one end of the fourth resistor, the other end of the fourth resistor, one pole of the sixth capacitor, and the anode of the voltage reference chip are all connected to the signal ground, the other pole of the sixth capacitor, the cathode of the voltage reference chip, and the reference end of the voltage reference chip are all connected to the inverting input end of the first comparator, one end of the fifth resistor is connected to the DC input source, the other end of the fifth resistor is connected to the cathode of the voltage reference chip, and one end of the sixth resistor is connected to the DC input source. A DC input source, the other end of the sixth resistor and one end of the seventh resistor are both connected to the non-inverting input of the first comparator, the other end of the seventh resistor is connected to signal ground, the non-inverting input of the second comparator is connected to the reference end of the voltage reference chip, the inverting input of the second comparator is connected to the short-circuit between the third resistor and the fourth resistor, the output of the first comparator and the output of the second comparator are respectively connected to the input of a logic OR gate, the output of the logic OR gate is connected to one end of the eighth resistor, the other end of the eighth resistor is connected to the base of a transistor, the emitter of the transistor is connected to signal ground, the collector of the transistor is connected to the anode of a second diode, the cathode of the second diode is connected to a 15V DC auxiliary power supply, the energy storage element of a normally closed relay is connected in parallel with the second diode, and a fuse and a knife switch of the normally closed relay are connected in series in a branch between the DC input source access terminal and the input terminal of the Flyback DC / DC multi-channel output circuit.

3. The high-efficiency, low-cross-regulation, multi-output power supply according to claim 1, characterized in that: The synchronous rectification unit includes: a third comparator, a fifteenth resistor, a sixteenth resistor, and a seventeenth resistor, wherein the third comparator is powered by a 5V DC auxiliary power supply output by the auxiliary source circuit, one end of the sixteenth resistor is connected to the 5V DC auxiliary power supply, the other end of the sixteenth resistor is connected to one end of the fifteenth resistor, the short-circuit between the sixteenth and fifteenth resistors is connected to the non-inverting input of the third comparator, the other end of the fifteenth resistor is connected to the signal ground, one end of the seventeenth resistor is connected to the PWM signal output by the control loop, the other end of the seventeenth resistor is connected to the inverting input of the third comparator, the output of the third comparator outputs a signal for turning off two MOS transistors on the secondary side of the Flyback DC / DC multi-channel output circuit, and the voltage at the short-circuit between the sixteenth and fifteenth resistors is a threshold voltage for distinguishing high and low levels of the PWM signal output by the control loop.

4. A high-efficiency, low-cross-regulation, multi-output power supply according to claim 3, characterized in that: The output adjustment unit includes: an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a twenty-first resistor, a ninth capacitor, a fourth comparator, and a fifth comparator. The fourth and fifth comparators are powered by a 5V DC auxiliary power supply output by the auxiliary source circuit. One end of the nineteenth resistor is connected to a sampling signal of a DC voltage signal output by the Flyback DC / DC multi-channel output circuit. The other end of the nineteenth resistor is connected to an inverting input of the fifth comparator. One end of the twentieth resistor is connected to the 5V DC auxiliary power supply. The other end of the twentieth resistor is connected to one end of the twenty-first resistor. A shorting point between the twentieth and twenty-first resistors is connected to a non-inverting input of the fifth comparator. The other end of the twenty-first resistor is connected to a signal ground. A branch connected in series with the eighteenth resistor and the ninth capacitor is connected between the inverting input and output of the fifth comparator. The non-inverting input of the fourth comparator is connected to the output of the fifth comparator. The inverting input of the fourth comparator is connected to a triangular carrier signal. The output of the fourth comparator outputs PWM1 for adjusting the DC signal output by the Flyback DC / DC multi-channel output circuit.

5. A high-efficiency, low-cross-regulation, multi-output power supply according to claim 4, characterized in that: The triangular carrier signal is generated by a triangular carrier generating unit, which includes: a twenty-second resistor, a twenty-third resistor, a twenty-fourth resistor, a sliding rheostat, a tenth capacitor, a transistor, a sixth comparator, and a seventh comparator, wherein the sixth comparator and the seventh comparator are powered by a 5V DC auxiliary power supply output by the auxiliary source circuit, one end of the twenty-third resistor is connected to the 5V DC auxiliary power supply, the other end of the twenty-third resistor and one end of the twenty-second resistor are short-circuited and connected to the non-inverting input end of the sixth comparator, the other end of the twenty-second resistor is connected to the signal ground, one end of the sliding rheostat is connected to the signal ground, the other end of the sliding rheostat, one electrode of the tenth capacitor, and the emitter of the transistor are all connected to the inverting input end of the sixth comparator, the other electrode of the tenth capacitor, the collector of the transistor, and one end of the twenty-fourth resistor are all connected to the output end of the sixth comparator, the inverting input end of the seventh comparator is connected to the 5V DC auxiliary power supply, the output end of the seventh comparator is connected to the base of the transistor, and the non-inverting input end of the seventh comparator is connected to the other end of the twenty-fourth resistor to serve as the output end of the triangular carrier signal.

6. A high-efficiency, low-cross-regulation, multi-output power supply according to claim 5, characterized in that: According to the constraint condition that the threshold voltage is greater than the minimum voltage of the triangular carrier, the resistance value R15 of the fifteenth resistor, the resistance value R16 of the sixteenth resistor, the resistance value R22 of the twenty-second resistor, and the resistance value R23 of the twenty-third resistor are determined to meet

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