Open-loop forward auxiliary power supply

Abstract

The utility model belongs to the technical field of power electronics and power management, and discloses an open-loop forward type auxiliary power supply, which comprises a PWM (Pulse Width Modulation) source module, an isolated open-loop forward circuit module and a plurality of groups of output voltage modules, and is characterized in that the PWM source module drives and controls the isolated open-loop forward circuit module through PWM signals; the isolated open-loop forward circuit module is electrically connected with the plurality of groups of output voltage modules and outputs a plurality of mutually isolated voltages at the same time; the isolated open-loop forward circuit module mainly comprises an MOS (Metal Oxide Semiconductor) tube, a transformer and at least one group of output power supplies, the MOS tube needs a group of PWM (Pulse-Width Modulation) signals to be driven, and the isolated open-loop forward circuit module further comprises a plurality of fly-wheel diodes, a filtering energy-storage capacitor, a voltage-regulator tube and a dummy load resistor. The system has the advantages of being high in portability, low in cost and stable in performance.

Description

Technical Field

[0001] The utility model belongs to the technical field of power electronics and power management, and more specifically, relates to an open-loop forward auxiliary power supply. Background Art

[0002] Power-type electrical equipment such as uninterruptible power supply equipment, photovoltaic inverters, and photovoltaic chargers have gradually been popularized around the world. Such power equipment is mainly composed of power circuits, auxiliary source circuits, and control circuits that work closely together. The operation of the power circuits and control circuits requires the auxiliary source circuit to power their power devices, and the power circuits and auxiliary source circuits are controlled by the control system circuit.

[0003] Most companies in the industry today use flyback power supplies as auxiliary power supplies for their equipment. Some medium and large inverter system circuits have complex power supply requirements and require a large number of positive and negative power supply paths. Using a universal flyback power supply circuit to solve these problems would be expensive, require many components, occupy a large amount of circuit board space, and weaken product competitiveness.

[0004] To this end, the utility model provides an open-loop forward auxiliary power supply. Summary of the Invention

[0005] In view of the above-mentioned problems existing in the existing technology, the purpose of the present invention is to provide an open-loop forward auxiliary power supply with the advantages of strong portability, cost advantage and stable performance.

[0006] The purpose of this utility model can be achieved through the following technical solutions:

[0007] An open-loop forward auxiliary power supply includes a PWM source module, an isolated open-loop forward circuit module, and several groups of output voltage modules. The PWM source module drives and controls the isolated open-loop forward circuit module through a PWM signal. The isolated open-loop forward circuit module is electrically connected to the several groups of output voltage modules and simultaneously outputs multiple mutually isolated voltages.

[0008] The isolated open-loop forward circuit module mainly includes a MOS tube, a transformer and at least one set of output power supplies. The MOS tube requires a set of PWM signals as a drive. The isolated open-loop forward circuit module also includes several freewheeling diodes, filter energy storage capacitors, voltage regulator tubes and dummy load resistors.

[0009] As a further preferred technical scheme of the utility model, the PWM source module includes control chip U1, the model of control chip U1 is UC3845 chip, control chip U1 is provided with COMP pin, Vfb pin, Isense pin, RT / CT pin, Vref pin, Vi pin, OUTPUT pin and GND pin, the Isense pin of control chip U1 is electrically connected with resistance R3, the other end of resistance R3 is electrically connected with ground GND, the RT / CT pin of control chip U1 is electrically connected with resistance R2 and capacitor C3, the other end of capacitor C3 is electrically connected with ground GND,

[0010] The COMP pin of control chip U1 is electrically connected with capacitor C2, the COMP pin of control chip U1 is electrically connected with triode Q1, specifically, the COMP pin of control chip U1 is electrically connected with the wiring point 2 of triode Q1, the wiring point 1 of triode Q1 is electrically connected with resistance R1 and capacitor C1, the other end of capacitor C1, the wiring point 3 of triode Q1 and the other end of capacitor C2 are electrically connected with ground GND,

[0011] The Vref pin of control chip U1 is electrically connected with the other end of resistance R2 and the other end of resistance R1, the Vfb pin of control chip U1 is electrically connected with ground GND, the Vi pin of control chip U1 is connected with +12V, the OUTPUT pin of control chip U1 outputs the PWM signal of 50Hz and maximum 50% duty cycle outward, the GND pin of control chip U1 is electrically connected with ground GND.

[0012] As a further preferred technical scheme of the utility model, the PWM source module includes inverter CPU, the inverter CPU is provided with two H bridge drivers, two H bridge drivers are connected with voltage amplifier and respectively output PWM1 signal and PWM2 signal outward,

[0013] The inverter CPU is provided with PWM pin, the PWM pin is connected with voltage amplifier and outputs PWM signal outward.

[0014] As a further preferred technical scheme of the utility model, the transformer of the isolating ring forward circuit module is isolation transformer TX1, the isolation transformer TX1 includes 5 windings, wherein 2 primary windings N1 and N2 are connected in series at the beginning and are wound, windings N3 to N5 are wound respectively.

[0015] As a further preferred technical scheme of the utility model, the isolating ring forward circuit module further includes resistance R23, one end of resistance R23 is connected with the PWM signal output by the PWM source module, the other end of resistance R23 is electrically connected with resistance R24 and triode Q10, the D connection point of MOS tube Q10 is electrically connected with the pin 9 of winding N1, the common pin 8 of winding N1 and winding N2 is electrically connected with diode D5 and capacitor C5, the other end of diode D5 is connected with +12V and is electrically connected with capacitor C4, the pin 7 of winding N2 is electrically connected with capacitor C6, the other end of capacitor C4, the other end of resistance R24, the S connection point of MOS tube Q10, the other end of capacitor C6 and the other end of capacitor C5 are electrically connected with ground GND.

[0016] As a further preferred technical scheme of the utility model, the pin 4 of winding N5 is electrically connected with diode D4, the other end of diode D4 is electrically connected with resistance R18, the other end of resistance R18 is electrically connected with energy storage capacitor EC5 and resistance R20, the other end of energy storage capacitor EC5 is electrically connected with energy storage capacitor EC6, the other end of resistance R20 is electrically connected with resistance R22, the pin BAT- is connected between energy storage capacitor EC5 and energy storage capacitor EC6 and between resistance R20 and resistance R22, and the pin BAT- is also connected with stabilizing diode ZD3.

[0017] The other end of resistance R18 is also connected with chip U4 and resistance R19, the other end of resistance R19 is electrically connected with resistance R21, and the connection point 1 of chip U4 is electrically connected between resistance R19 and resistance R21.

[0018] The connection point 2 of chip U4, the other end of resistance R21, the other end of energy storage capacitor EC6, the other end of resistance R22 and the other end of stabilizing diode ZD3 are all electrically connected with the pin 4 of N5.

[0019] As a further preferred technical scheme of the utility model, the pin 6 of winding N4 is electrically connected with diode D3, the other end of diode D4 is electrically connected with resistance R9, the other end of resistance R9 is electrically connected with energy storage capacitor EC2 and resistance R13, the other end of energy storage capacitor EC2 is electrically connected with energy storage capacitor EC4, the other end of resistance R13 is electrically connected with resistance R17, the pin MID2 is connected between energy storage capacitor EC2 and energy storage capacitor EC4 and between resistance R13 and resistance R17, and the pin MID2 is also connected with stabilizing diode ZD1.

[0020] The other end of the resistor R9 is also connected with a chip U3 and a resistor R12, the other end of the resistor R12 is connected with a resistor R16, and the resistor R12 and the resistor R16 are connected with a connecting point 1 of the chip U3;

[0021] The connecting point 2 of the chip U3, the other end of the resistor R16, the other end of an energy storage capacitor EC4, the other end of a resistor R17 and the other end of a voltage stabilizing diode ZD1 are all connected with a pin 5 of the N4.

[0022] As the further preferred technical scheme of the utility model, the pin 2 of the winding N3 is connected with a diode D2, the other end of the diode D2 is connected with a resistor R8, the other end of the resistor R8 is connected with an energy storage capacitor EC1 and a resistor R10, the other end of the energy storage capacitor EC1 is connected with an energy storage capacitor EC3, the other end of the resistor R10 is connected with a resistor R14, the energy storage capacitor EC1 and the energy storage capacitor EC3 and the resistor R10 and the resistor R14 are all connected with a pin BAT-, and the pin BAT- is also connected with a voltage stabilizing diode ZD2.

[0023] The other end of the resistor R8 is also connected with a chip U2 and a resistor R11, the other end of the resistor R11 is connected with a resistor R15, and the resistor R11 and the resistor R15 are connected with a connecting point 1 of the chip U2.

[0024] The connecting point 2 of the chip U2, the other end of the resistor R15, the other end of the energy storage capacitor EC3, the other end of the resistor R14 and the other end of the voltage stabilizing diode ZD2 are all connected with a pin 1 of the N3.

[0025] As the further preferred technical scheme of the utility model, the isolating ring forward circuit module is connected with an overvoltage protection circuit, specifically, the two ends of the transformer of the isolating ring forward circuit module are connected with MOS tube Q2 and MOS tube Q4 and MOS tube Q3 and MOS tube Q5 respectively.

[0026] The MOS tube Q3 is connected with a resistor R6, the other end of the resistor R6 is connected with an NPN triode Q6 and a PNP triode Q8, the connecting point 1 of the NPN triode Q6 and the connecting point 1 of the PNP triode Q8 are all connected with a resistor R4, and the other end of the resistor R4 is connected with a PWM2 signal.

[0027] The MOS tube Q5 is electrically connected with the resistor R7, the other end of the resistor R7 is electrically connected with the NPN triode Q7 and the PNP triode Q9, the wiring point 1 of the NPN triode Q7 and the wiring point 1 of the PNP triode Q9 are electrically connected with the resistor R5, and the other end of the resistor R5 is connected with the PWM1 signal.

[0028] As described above, the open-loop forward auxiliary power supply has the following beneficial effects:

[0029] 1. Strong portability: the utility model is matched with the existing general auxiliary power supply circuit and is used in expansion, realizes the utility of outputting multiple positive and negative voltages at low cost, and a single PWM source can drive multiple isolated open-loop forward circuit modules at the same time, without multiple PWM sources, and the circuit is flexible, material is saved, and cost is saved.

[0030] 2. Cost advantage: compared with the existing conventional scheme, the number of circuit devices of the patent is reduced, the number of transformer windings is reduced, the circuit space is small, the control scheme is simple, and the cost can be greatly reduced.

[0031] 3. Stable performance: the isolated open-loop forward circuit module of the utility model can be additionally matched with an overvoltage protection circuit, so that each winding of the isolated open-loop forward circuit module can play a voltage stabilizing limiting role when the input / output voltage is overvoltage.

[0032] The additional aspects and advantages of the utility model will be partially given in the following description, some will become obvious from the following description, or will be understood through the practice of the utility model. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or the prior art description, obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can be obtained according to these drawings without creative labor.

[0034] Figure 1 It is a frame principle diagram of the open-loop forward auxiliary power supply applied by the utility model;

[0035] Figure 2 It is a circuit structure diagram of the PWM source module of the open-loop forward auxiliary power supply applied by the utility model;

[0036] Figure 3 It is a circuit structure diagram of the PWM source module of the open-loop forward auxiliary power supply applied by the utility model;

[0037] Figure 4 This is a circuit structure diagram of an isolated open-loop forward circuit module of an open-loop forward auxiliary power supply applied for by the utility model;

[0038] Figure 5 This is a circuit structure diagram of an isolated open-loop forward circuit module of an open-loop forward auxiliary power supply applied for by the utility model and an overvoltage protection circuit. DETAILED DESCRIPTION

[0039] The following describes the implementation of the present invention through specific embodiments. People familiar with this technology can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0040] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content. The specific structure can be described with reference to the drawings of the patent application.

[0041] The utility model provides an open-loop forward auxiliary power supply. Figures 1 to 5 As shown, it includes a PWM source module, an isolated open-loop forward circuit module and several groups of output voltage modules. The PWM source module drives and controls the isolated open-loop forward circuit module through a PWM signal. The isolated open-loop forward circuit module is electrically connected to the several groups of output voltage modules and simultaneously outputs multiple mutually isolated voltages.

[0042] The isolated open-loop forward circuit module mainly includes a MOS tube, a transformer and at least one set of output power supplies. The MOS tube requires a set of PWM signals as a drive. The isolated open-loop forward circuit module also includes several freewheeling diodes, filter energy storage capacitors, voltage regulator tubes and dummy load resistors.

[0043] Combine Figure 4 As shown, the transformer of the isolated open-loop forward circuit module is an isolation transformer TX1. The isolation transformer TX1 includes five windings, wherein two primary windings N1 and N2 are wound in series, and windings N3 to N5 are wound separately.

[0044] The isolation ring forward circuit module further comprises a resistor R23, one end of the resistor R23 is connected to the PWM signal output by the PWM source module, the other end of the resistor R23 is electrically connected with a resistor R24 and a transistor Q10, the D connection point of the MOS transistor Q10 is electrically connected with a pin 9 of a winding N1, the common pin 8 of the winding N1 and a winding N2 is electrically connected with a diode D5 and a capacitor C5, the other end of the diode D5 is connected to +12V and electrically connected with a capacitor C4, a pin 7 of the winding N2 is electrically connected with a capacitor C6, the other end of the capacitor C4, the other end of the resistor R24, the S connection point of the MOS transistor Q10, the other end of the capacitor C6 and the other end of the capacitor C5 are electrically connected with the ground GND.

[0045] The pin 4 of the winding N5 is electrically connected with a diode D4, the other end of the diode D4 is electrically connected with a resistor R18, the other end of the resistor R18 is electrically connected with an energy storage capacitor EC5 and a resistor R20, the other end of the energy storage capacitor EC5 is electrically connected with an energy storage capacitor EC6, the other end of the resistor R20 is electrically connected with a resistor R22, the energy storage capacitor EC5 and the energy storage capacitor EC6 and the resistor R20 and the resistor R22 are both connected with the pin BAT-.

[0046] The other end of the resistor R18 is further connected with a chip U4 and a resistor R19, the other end of the resistor R19 is electrically connected with a resistor R21, the resistor R19 and the resistor R21 are electrically connected with a connection point 1 of the chip U4.

[0047] The connection point 2 of the chip U4, the other end of the resistor R21, the other end of the energy storage capacitor EC6, the other end of the resistor R22 and the other end of the voltage stabilizing diode ZD3 are all electrically connected with the pin 4 of the N5.

[0048] The pin 6 of the winding N4 is electrically connected with a diode D3, the other end of the diode D4 is electrically connected with a resistor R9, the other end of the resistor R9 is electrically connected with an energy storage capacitor EC2 and a resistor R13, the other end of the energy storage capacitor EC2 is electrically connected with an energy storage capacitor EC4, the other end of the resistor R13 is electrically connected with a resistor R17, the energy storage capacitor EC2 and the energy storage capacitor EC4 and the resistor R13 and the resistor R17 are both connected with a pin MID2, the pin MID2 is further connected with a voltage stabilizing diode ZD1.

[0049] The other end of the resistor R9 is also connected with the chip U3 and the resistor R12, the other end of the resistor R12 is connected with the resistor R16, the resistor R12 and the resistor R16 are connected with the connecting point 1 of the chip U3;

[0050] The connecting point 2 of the chip U3, the other end of the resistor R16, the other end of the energy storage capacitor EC4, the other end of the resistor R17 and the other end of the voltage stabilizing diode ZD1 are all connected with the pin 5 of the N4.

[0051] The pin 2 of the winding N3 is connected with the diode D2, the other end of the diode D2 is connected with the resistor R8, the other end of the resistor R8 is connected with the energy storage capacitor EC1 and the resistor R10, the other end of the energy storage capacitor EC1 is connected with the energy storage capacitor EC3, the other end of the resistor R10 is connected with the resistor R14, the energy storage capacitor EC1 and the energy storage capacitor EC3 and the resistor R10 and the resistor R14 are all connected with the pin BAT-, and the pin BAT- is also connected with the voltage stabilizing diode ZD2.

[0052] The other end of the resistor R8 is also connected with the chip U2 and the resistor R11, the other end of the resistor R11 is connected with the resistor R15, the resistor R11 and the resistor R15 are connected with the connecting point 1 of the chip U2.

[0053] The connecting point 2 of the chip U2, the other end of the resistor R15, the other end of the energy storage capacitor EC3, the other end of the resistor R14 and the other end of the voltage stabilizing diode ZD2 are all connected with the pin 1 of the N3.

[0054] It should be noted that the operation process of the isolation ring forward circuit module is as follows:

[0055] When the PWM signal is in a high state, the MOS tube Q10 is driven to be turned on through current limiting by the resistor R23 and voltage division by the resistor R24, +12V excites the transformer through the winding N1 after passing through the diode D5 (the voltage at the pin 8 of the winding N1 is positive), and according to the winding direction and the turn ratio relationship, taking the winding N5 as an example: the induction voltage at the pin 4 of the winding N5 and the pin 8 of the winding N1 is positive and the winding voltage is proportional to the winding turns, the diode D4 is forward conducting, and after current limiting by the resistor R18, the energy storage capacitors EC5 and EC6 are charged, wherein the voltage division of the energy storage capacitors EC5 and EC6 is mainly determined by the voltage division of the external dummy load resistors R20 and R22 and the auxiliary adjustment of the voltage stabilizing diode ZD3, and the voltage division of R16 and R17 is coarsely adjusted according to the voltage division ratio, in addition, the voltage requirements of +16V and -7V can be stably obtained through the auxiliary adjustment of the externally added voltage stabilizing diode (for example, a 6.8V voltage stabilizing diode), and the midpoint of the voltage division capacitor is used as a reference base point and a driving potential reference point for connecting the driven objects (such as MOS tubes, IGBTs, etc.). In some application scenarios, the circuit reliability is increased;

[0056] In addition, the chip U4 and the voltage division sampling resistors R19 and R21 are added, when the winding coupling is not good or the input / output voltage overshoot occurs, the voltage division of the resistors R19 and R21 exceeds 2.5V, so that the chip U3 works to pull current from the connection point 3 thereof, and then the current passes through the resistor R18 to consume part of the voltage, so that the total voltage of the energy storage capacitors EC5 and EC6 remains unchanged, thereby playing an additional overvoltage protection role, and the chip U4 is in a dormant state with extremely low loss under normal working conditions of the output voltage. During this period, the winding N2 is reverse blocked due to the existence of the diode D4, and no current flows through, and the chips U4, U3 and U2 are commonly used TL431 chips (the windings N3 and N4 are the same, and are not described again);

[0057] When the PWM signal is in a low state, the MOS tube Q10 is cut off, and the windings N1 and the same name ends of each winding induce reverse electromotive force, and due to the existence of the diodes D2, D3, D4 and D5, the transformer TX1 does not supply power to each winding, and the pin 8 of the winding N2 is a positive voltage, the capacitors C5 and C6 continue to flow to consume the excitation magnetic energy in the magnetic core of the transformer, so that the magnetic flux of the transformer is reset to reach the volt-second balance state, so as to prevent the magnetic flux saturation of the transformer after multiple working periods and damage the circuit.

[0058] As shown in the combination Figure 5 The isolation loop forward circuit module is connected with the overvoltage protection circuit, specifically, two ends of the transformer of the isolation loop forward circuit module are connected with the MOS tube Q2 and the MOS tube Q4 and the MOS tube Q3 and the MOS tube Q5 respectively;

[0059] The MOS tube Q3 is electrically connected with the resistor R6, the other end of the resistor R6 is electrically connected with the NPN triode Q6 and the PNP triode Q8, the wiring point 1 of the NPN triode Q6 and the wiring point 1 of the PNP triode Q8 are electrically connected with the resistor R4, and the other end of the resistor R4 is connected with the PWM2 signal.

[0060] The MOS tube Q5 is electrically connected with the resistor R7, the other end of the resistor R7 is electrically connected with the NPN triode Q7 and the PNP triode Q9, the wiring point 1 of the NPN triode Q7 and the wiring point 1 of the PNP triode Q9 are electrically connected with the resistor R5, and the other end of the resistor R5 is connected with the PWM1 signal.

[0061] It should be noted that the resistors R4, R5, R6 and R7 are current limiting resistors, the NPN triodes Q6 and Q7 and the PNP triodes Q8 and Q9 form a general push-pull drive circuit to enhance the driving capability of the PWM1 or PWM2 signal, when the NPN triodes Q6 and Q7 are turned on, a positive voltage is applied to the gate of the driven device to make the device conduct, when the PNP triodes Q8 and Q9 are turned on, a negative voltage is applied to the gate of the driven device to make the driven device stably turn off, even if there is voltage glitch / oscillation interference, the driven device will not be mistakenly turned on to cause damage, and the system is more stable and reliable.

[0062] The PWM source module has two embodiments, and specifically as follows: Embodiment 1

[0063] Combined Figure 2 As shown in the figure, the PWM source module comprises a control chip U1, the model of the control chip U1 is a UC3845 chip, the control chip U1 is provided with a COMP pin, a Vfb pin, an Isense pin, an RT / CT pin, a Vref pin, a Vi pin, an OUTPUT pin and a GND pin, the Isense pin of the control chip U1 is electrically connected with a resistor R3, the other end of the resistor R3 is electrically connected with a ground GND, the RT / CT pin of the control chip U1 is electrically connected with a resistor R2 and a capacitor C3, and the other end of the capacitor C3 is electrically connected with the ground GND.

[0064] The COMP pin of the control chip U1 is electrically connected with a capacitor C2, the COMP pin of the control chip U1 is electrically connected with a triode Q1, specifically, the COMP pin of the control chip U1 is electrically connected with a wiring point 2 of the triode Q1, the wiring point 1 of the triode Q1 is electrically connected with a resistor R1 and a capacitor C1, and the other end of the capacitor C1, a wiring point 3 of the triode Q1 and the other end of the capacitor C2 are electrically connected with the ground GND.

[0065] The Vref pin of the control chip U1 is electrically connected with the other end of the resistor R2 and the other end of the resistor R1, the Vfb pin of the control chip U1 is electrically connected with the ground GND, the Vi pin of the control chip U1 is connected with +12V, the OUTPUT pin of the control chip U1 outputs a PWM signal with 50Hz and a maximum 50% duty cycle, and the GND pin of the control chip U1 is electrically connected with the ground GND.

[0066] It should be noted that, in the embodiment one,

[0067] The chip U1 uses the UC3845 chip of the ON company to build an open-loop control output PWM signal, the resistor R3 is a potential pull-down resistor, and the resistor R3 is a prerequisite for the chip U1 to output a maximum 50% duty cycle, the resistor R2 and the capacitor C3 are combined with the internal circuit of the chip U1 to form a shock loop, and the output switching frequency of the chip U1 can be adjusted by adjusting the values of the resistor R2 and the capacitor C3.

[0068] The capacitor C2 plays a soft starting role, the capacitor C2 capacitor voltage is 0V in the power-off state, the higher the output voltage of the chip U1, the greater the PWM duty cycle of the output, the chip U1 outputs a 5V reference voltage after power-on, the capacitor C1 is charged through the resistor R1, as the voltage of the capacitor C1 gradually rises, the PNP type triode Q1 gradually transitions from the on state to the off state, the voltage of the capacitor C2 gradually rises with the voltage of the capacitor C1 (C1 is a filter capacitor with small capacity), and the PWM duty cycle of the output of the chip U1 gradually widens from small to large, and finally expands to the maximum duty cycle, so that the soft starting role of the output is achieved.

[0069] The Pin8 outputs a 5V reference voltage after power-on, the capacitor C1 is charged through the resistor R1, as the voltage of the capacitor C1 gradually rises, the PNP type triode Q1 gradually transitions from the on state to the off state, the voltage of the capacitor C2 gradually rises with the voltage of the capacitor C1 (C1 is a filter capacitor with small capacity), and the PWM duty cycle of the output of the chip U1 gradually widens from small to large, and finally expands to the maximum duty cycle, so that the soft starting role of the output is achieved. Embodiment 2

[0070] Combined Figure 3 As shown, the PWM source module comprises an inverter CPU, the inverter CPU is provided with two H-bridge drivers, the two H-bridge drivers are connected with a voltage amplifier and respectively output PWM1 signal and PWM2 signal to the outside;

[0071] The inverter CPU is provided with a PWM pin, the PWM pin is connected with the voltage amplifier and outputs a PWM signal to the outside.

[0072] It is apparent for a person skilled in the art that the present application is not restricted to the details of the above exemplary embodiments, but that it can be implemented in other concrete forms without departing from the spirit or the essential characteristics of the present application. Therefore, the embodiments should be considered as exemplary only, and not limiting, the scope of the present application being defined by the appended claims rather than the above description, and all changes coming within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference signs in the claims should not be construed as limiting the claims concerned.

Claims

1. An open-loop forward-type auxiliary power supply, characterized by comprising: The PWM source module, the isolation loop forward circuit module and a plurality of groups of output voltage modules, the PWM source module drives and controls the isolation loop forward circuit module through a PWM signal, the isolation loop forward circuit module is electrically connected with the plurality of groups of output voltage modules and simultaneously outputs a plurality of mutually isolated voltages; The isolation loop forward circuit module mainly comprises a MOS tube, a transformer and at least one group of output power supplies, the MOS tube needs a group of PWM signals as a drive, and the isolation loop forward circuit module further comprises a plurality of freewheeling diodes, a filter energy storage capacitor, a voltage stabilizing tube and a dummy load resistor.

2. The open-loop forward-type auxiliary power supply according to claim 1, characterized by, The PWM source module comprises a control chip U1, the control chip U1 is a UC3845 chip, the control chip U1 is provided with a COMP pin, a Vfb pin, an Isense pin, an RT / CT pin, a Vref pin, a Vi pin, an OUTPUT pin and a GND pin, the Isense pin of the control chip U1 is electrically connected with a resistor R3, the other end of the resistor R3 is electrically connected with a ground GND, the RT / CT pin of the control chip U1 is electrically connected with a resistor R2 and a capacitor C3, and the other end of the capacitor C3 is electrically connected with the ground GND; The COMP pin of the control chip U1 is electrically connected with a capacitor C2, the COMP pin of the control chip U1 is electrically connected with a triode Q1, specifically, the COMP pin of the control chip U1 is electrically connected with a wiring point 2 of the triode Q1, the wiring point 1 of the triode Q1 is electrically connected with a resistor R1 and a capacitor C1, the other end of the capacitor C1, a wiring point 3 of the triode Q1 and the other end of the capacitor C2 are electrically connected with the ground GND; The Vref pin of the control chip U1 is electrically connected with the other end of the resistor R2 and the other end of the resistor R1, the Vfb pin of the control chip U1 is electrically connected with the ground GND, the Vi pin of the control chip U1 is connected with +12V, the OUTPUT pin of the control chip U1 outputs a PWM signal with a frequency of 50Hz and a maximum duty cycle of 50% outwardly, and the GND pin of the control chip U1 is electrically connected with the ground GND.

3. The open-loop forward auxiliary power supply of claim 1, wherein, The PWM source module comprises an inverter CPU, the inverter CPU is provided with two H-bridge drivers, the two H-bridge drivers are both connected with a voltage amplifier and respectively output a PWM1 signal and a PWM2 signal outwardly. The inverter CPU is provided with a PWM pin, the PWM pin is connected with the voltage amplifier and outputs a PWM signal outwardly.

4. The open-loop forward auxiliary power supply of claim 1, wherein, The transformer of the isolation loop forward circuit module is an isolation transformer TX1, and the isolation transformer TX1 comprises five windings, wherein two primary windings N1 and N2 are connected in series at the beginning and are wound, and windings N3 to N5 are wound respectively.

5. A forward-type auxiliary switching mode power supply according to claim 4, wherein, The isolation ring forward circuit module further comprises a resistor R23, one end of the resistor R23 is connected to the PWM signal output by the PWM source module, the other end of the resistor R23 is electrically connected with a resistor R24 and a transistor Q10, the D connection point of the MOS transistor Q10 is electrically connected with a pin 9 of a winding N1, the common pin 8 of the winding N1 and a winding N2 is electrically connected with a diode D5 and a capacitor C5, the other end of the diode D5 is connected to +12V and electrically connected with a capacitor C4, a pin 7 of the winding N2 is electrically connected with a capacitor C6, the other end of the capacitor C4, the other end of the resistor R24, the S connection point of the MOS transistor Q10, the other end of the capacitor C6 and the other end of the capacitor C5 are electrically connected with the ground GND.

6. The open-loop forward auxiliary power supply of claim 4, wherein, The pin 4 of the winding N5 is electrically connected with a diode D4, the other end of the diode D4 is electrically connected with a resistor R18, the other end of the resistor R18 is electrically connected with an energy storage capacitor EC5 and a resistor R20, the other end of the energy storage capacitor EC5 is electrically connected with an energy storage capacitor EC6, the other end of the resistor R20 is electrically connected with a resistor R22, the energy storage capacitor EC5 and the energy storage capacitor EC6 and the resistor R20 and the resistor R22 are electrically connected with the pin BAT-; The other end of the resistor R18 is further connected with a chip U4 and a resistor R19, the other end of the resistor R19 is electrically connected with a resistor R21, the resistor R19 and the resistor R21 are electrically connected with a connection point 1 of the chip U4; The connection point 2 of the chip U4, the other end of the resistor R21, the other end of the energy storage capacitor EC6, the other end of the resistor R22 and the other end of the voltage stabilizing diode ZD3 are electrically connected with the pin 4 of the N5.

7. The open-loop forward auxiliary power supply of claim 4, wherein, The pin 6 of the winding N4 is electrically connected with a diode D3, the other end of the diode D4 is electrically connected with a resistor R9, the other end of the resistor R9 is electrically connected with an energy storage capacitor EC2 and a resistor R13, the other end of the energy storage capacitor EC2 is electrically connected with an energy storage capacitor EC4, the other end of the resistor R13 is electrically connected with a resistor R17, the energy storage capacitor EC2 and the energy storage capacitor EC4 and the resistor R13 and the resistor R17 are electrically connected with the pin MID2, and the pin MID2 is further connected with a voltage stabilizing diode ZD1. The other end of the resistor R9 is further connected with a chip U3 and a resistor R12, the other end of the resistor R12 is electrically connected with a resistor R16, the resistor R12 and the resistor R16 are electrically connected with a connection point 1 of the chip U3; The connection point 2 of the chip U3, the other end of the resistor R16, the other end of the energy storage capacitor EC4, the other end of the resistor R17 and the other end of the voltage stabilizing diode ZD1 are electrically connected with the pin 5 of the N4.

8. The open-loop forward auxiliary power supply of claim 4, wherein, The pin 2 of the winding N3 is electrically connected with a diode D2, the other end of the diode D2 is electrically connected with a resistor R8, the other end of the resistor R8 is electrically connected with an energy storage capacitor EC1 and a resistor R10, the other end of the energy storage capacitor EC1 is electrically connected with an energy storage capacitor EC3, the other end of the resistor R10 is electrically connected with a resistor R14, the energy storage capacitor EC1 and the energy storage capacitor EC3 and the resistor R10 and the resistor R14 are electrically connected with a pin BAT- between them, and the pin BAT- is also connected with a voltage stabilizing diode ZD2; The other end of the resistor R8 is also connected with a chip U2 and a resistor R11, the other end of the resistor R11 is electrically connected with a resistor R15, and the resistor R11 and the resistor R15 are electrically connected with a wiring point 1 of the chip U2; The wiring point 2 of the chip U2, the other end of the resistor R15, the other end of the energy storage capacitor EC3, the other end of the resistor R14 and the other end of the voltage stabilizing diode ZD2 are all electrically connected with a pin 1 of the N3.

9. The open-loop forward auxiliary power supply of claim 1, wherein, The isolation ring forward circuit module is connected with an overvoltage protection circuit, specifically, the two ends of the transformer of the isolation ring forward circuit module are respectively connected with MOS tubes Q2 and Q4 and MOS tubes Q3 and Q5; The MOS tube Q3 is electrically connected with a resistor R6, the other end of the resistor R6 is electrically connected with an NPN triode Q6 and a PNP triode Q8, the wiring point 1 of the NPN triode Q6 and the wiring point 1 of the PNP triode Q8 are all electrically connected with a resistor R4, and the other end of the resistor R4 is connected with a PWM2 signal; The MOS tube Q5 is electrically connected with a resistor R7, the other end of the resistor R7 is electrically connected with an NPN triode Q7 and a PNP triode Q9, the wiring point 1 of the NPN triode Q7 and the wiring point 1 of the PNP triode Q9 are all electrically connected with a resistor R5, and the other end of the resistor R5 is connected with a PWM1 signal.

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