Novel isolation power supply

Abstract

The invention belongs to the field of power electronics and integrated circuits, and particularly provides a novel isolation power supply which is used for solving the problems that a traditional isolation power supply is complex in system, high in system cost, not favorable for achieving high power density and the like due to a signal isolation device. The invention creatively provides a novel isolation power supply which comprises an isolation transformer, a power transmission circuit and a control circuit which are located on the primary side of the isolation transformer, and a rectification circuit and a feedback circuit which are located on the secondary side of the isolation transformer, and the isolation power supply comprises a power transmission state and a feedback state. Through the creative design that a power transmission state and a feedback state are alternately carried out, the same isolation transformer can be adopted for power transmission from a primary side circuit to a secondary side circuit and signal feedback from the secondary side circuit to the primary side circuit, stable output voltage is achieved on the premise that no extra signal isolation device is needed, and the reliability of the circuit is improved. And the high conversion efficiency can be kept in light-load work.

Description

Technical Field

[0001] The invention belongs to the field of power electronics and integrated circuits, and specifically provides a novel isolated power supply. Technical Background

[0002] As modern electronic devices have more and more working scenarios, in some application scenarios, in order to avoid the impact of external environmental interference on the safety and stability of electronic equipment, isolated power supplies are usually used. Isolation devices can achieve electrical isolation between the main circuit and the secondary circuit to ensure the safe operation of electronic equipment.

[0003] At present, traditional isolated power supplies such as Figure 1 As shown, a primary-side control scheme is adopted. In order to ensure that the power supply has a stable output voltage under different loads or unstable input voltages, the circuit usually requires feedback control based on the output voltage. Additional signal isolation devices (such as optocouplers) are required on the secondary side to transmit the feedback signal from the secondary circuit back to the primary circuit, thereby controlling the working state of the system. However, signal isolation devices will increase system cost and complexity, which is not conducive to achieving high power density. Summary of the invention

[0004] The purpose of the present invention is to provide a new type of isolated power supply to solve the problems of complex system, high system cost and difficulty in achieving high power density caused by signal isolation devices in traditional isolated power supplies; the present invention creatively proposes a new type of isolated power supply, including: an isolation transformer, a power transmission circuit and a control circuit located on the primary side of the isolation transformer, and a rectifier circuit and a feedback circuit located on the secondary side of the isolation transformer. The isolated power supply includes a power transmission state and a feedback state. Through the creative design of alternating power transmission state and feedback state, the power transmission from the primary circuit to the secondary circuit and the signal feedback from the secondary circuit to the primary circuit can use the same isolation transformer, without the need for additional signal isolation devices, to achieve a stable output voltage and maintain high conversion efficiency even when working under light load.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A novel isolated power supply comprises: an isolation transformer, a power transmission circuit and a control circuit located on the primary side of the isolation transformer, and a rectification circuit and a feedback circuit located on the secondary side of the isolation transformer; the characteristics are:

[0007] The isolated power supply includes a power transmission state and a feedback state, and the power transmission state and the feedback state are performed alternately;

[0008] The control circuit controls the power transmission circuit to be in a power transmission state, and the feedback circuit is in a standby state; the power transmission circuit converts the input voltage into an alternating voltage, drives the isolation transformer, the isolation transformer transmits the primary side alternating voltage to the secondary side to form a secondary side alternating voltage, and the rectifier circuit converts the secondary side alternating voltage into a DC voltage as a secondary side output voltage;

[0009] The control circuit monitors the duration of the power transmission state, and when the set duration is reached, the control circuit controls the power transmission circuit to enter the sleep state;

[0010] The feedback circuit monitors the voltage on the secondary side of the isolation transformer. When it is determined that the power transmission circuit enters a dormant state, the feedback circuit enters a feedback state, generates a secondary side feedback signal, and transmits the secondary side feedback signal to the secondary side of the isolation transformer. The isolation transformer transmits the secondary side feedback signal to the primary side to form a primary side feedback signal.

[0011] The control circuit receives the primary feedback signal and monitors the duration of the feedback state; the control circuit adjusts the power transmission circuit according to the primary feedback signal and the duration information of the feedback state, and controls the power transmission circuit to maintain the sleep state or enter the power transmission state again.

[0012] Further, the first input port of the power transmission circuit is coupled to the first port of the input voltage, the second input port of the power transmission circuit is coupled to the second port of the input voltage, the third input port of the power transmission circuit is coupled to the output end of the control circuit, the first output port of the power transmission circuit is coupled to the first port of the primary winding of the isolation transformer, and the second output port of the power transmission circuit is coupled to the second port of the primary winding of the isolation transformer; the first input port of the control circuit is coupled to the first port of the primary winding of the isolation transformer, and the second input port of the control circuit is coupled to the second port of the primary winding of the isolation transformer; the first input port of the rectifier circuit is coupled to the first port of the secondary winding of the isolation transformer, the second input port of the rectifier circuit is coupled to the second port of the secondary winding of the isolation transformer, the first output port of the rectifier circuit is coupled to the positive pole of the DC output voltage, and the second output port of the rectifier circuit is coupled to the negative pole of the DC output voltage; the first input port of the feedback circuit is coupled to the positive pole of the DC output voltage, the second input port of the feedback circuit is coupled to the negative pole of the DC output voltage, the third input port and the first output port of the feedback circuit are coupled to the first port of the secondary winding of the isolation transformer, and the fourth input port and the second output port of the feedback circuit are coupled to the second port of the secondary winding of the isolation transformer.

[0013] Furthermore, the control circuit includes: a third comparison unit, a fourth comparison unit, an oscillation circuit, a counting circuit, and a control signal generating circuit. The reverse input terminal of the third comparison unit is coupled to the third reference voltage, the positive input terminal of the third comparison unit serves as the first input port of the control circuit and receives the first primary feedback signal, and the output terminal of the third comparison unit is coupled to the first input port of the control signal generating circuit; the reverse input terminal of the fourth comparison unit is coupled to the fourth reference voltage, the positive input terminal of the fourth comparison unit serves as the second input port of the control circuit and receives the second primary feedback signal, and the output terminal of the fourth comparison unit is coupled to the second input port of the control signal generating circuit; the output terminal of the oscillation circuit is coupled to the input terminal of the counting circuit, and the input terminal of the counting circuit is coupled to the third input port of the control signal generating circuit; the output port of the control signal generating circuit serves as the output terminal of the control circuit to output the control signal.

[0014] Furthermore, the oscillation circuit and the counting circuit are used to monitor the duration of the power transmission state and the duration of the feedback state, and the third comparison unit and the fourth comparison unit receive the primary feedback signal; wherein, the oscillation circuit generates a system clock, the counting circuit generates a first set duration and a second set duration according to the system clock, and the control signal generation circuit generates a corresponding control signal according to the first set duration and the second set duration; in the power transmission state, within the first set duration, the control signal generation circuit controls the power transmission circuit to be in the power transmission state; in the feedback state, the third comparison unit and the fourth comparison unit compare, and within the second set duration, if the first primary feedback signal is greater than the third reference voltage an odd number of times or the second primary feedback signal is greater than the fourth reference voltage an odd number of times, then the control signal generation circuit controls the power transmission circuit to remain in the dormant state; if the first primary feedback signal is greater than the third reference voltage an even number of times or the second primary feedback signal input terminal is greater than the fourth reference voltage an even number of times, then the control signal generation circuit controls the power transmission circuit to enter the power transmission state.

[0015] The period of the alternating voltage is t 1 , the first set time length is the alternating voltage period t 1 n 1 times, the second set time length is the alternating voltage cycle t 1 n 2 times; n 1 The value range of n is 10 to 20. 2 The value range is 2 to 3.

[0016] Furthermore, the feedback circuit includes: a voltage sampling circuit, a first comparison unit, a second comparison unit, a feedback state determination circuit, and a signal synthesis circuit; the first input port of the voltage sampling circuit is coupled to the positive pole of the DC output voltage, the second input port of the voltage sampling circuit is coupled to the negative pole of the DC output voltage, and the output end of the voltage sampling circuit is coupled to the positive input end of the first comparison unit and the reverse input end of the second comparison unit; the reverse input end of the first comparison unit is coupled to the first reference voltage, the output end of the first comparison unit is coupled to the first input port of the signal synthesis circuit, the positive input end of the second comparison unit is coupled to the second reference voltage, and the output end of the second comparison unit is coupled to the second input port of the signal synthesis circuit; the first input port of the feedback state determination circuit is coupled as the third input port of the feedback circuit and inputs the first input signal, the second input port of the feedback state determination circuit is coupled as the fourth input port of the feedback circuit and inputs the second input signal, and the output port of the feedback state determination circuit is coupled to the third input port of the signal synthesis circuit; the first output end of the signal synthesis circuit serves as the first output port of the feedback circuit and outputs the first secondary feedback signal, and the first output end of the signal synthesis circuit serves as the second output port of the feedback circuit and outputs the second secondary feedback signal.

[0017] Furthermore, in the feedback circuit, the feedback state determination circuit monitors the secondary side voltage of the isolation transformer. When the time length during which the voltage difference between the first input signal and the second input signal is less than the first voltage threshold exceeds the first time threshold, it is determined that the power transmission circuit enters the sleep state and the feedback circuit enters the feedback state; the first comparison unit compares the output sampling voltage and the first reference voltage. If the output sampling voltage is less than the first reference voltage within the second set time length, the signal synthesis circuit generates a first type of feedback signal; if the output sampling voltage is greater than the first reference voltage within the second set time length, the signal synthesis circuit generates a second type of feedback signal, and after the signal synthesis circuit generates the second type of feedback signal once, the second comparator compares the output sampling voltage and the second reference voltage. If the output sampling voltage is less than the second reference voltage, the signal synthesis circuit generates a third type of feedback signal; the first type of feedback signal is a low-level signal, the second type of feedback signal is a high-level single pulse signal, and the third type of feedback signal is a high-level single pulse signal.

[0018] The first voltage threshold should be less than one fifth of the alternating voltage amplitude on the secondary winding of the isolation transformer, and the first time threshold should be greater than the alternating voltage period t 1 One half of .

[0019] The signal synthesis circuit comprises: a pulse signal generating circuit, a first feedback PMOS tube and a second feedback PMOS tube, wherein the first input port, the second input port and the third input port of the pulse signal generating circuit are respectively used as the first input port, the second input port and the third input port of the signal synthesis circuit, the first output end of the pulse signal generating circuit is coupled to the gate of the first feedback PMOS tube, the second output end of the pulse signal generating circuit is coupled to the gate of the second feedback PMOS tube, the source electrodes of the first feedback PMOS tube and the second feedback PMOS tube are coupled to a direct current output voltage, the drain electrode of the first feedback PMOS tube is used as the first output end of the signal synthesis circuit, and the drain electrode of the second feedback PMOS tube is used as the second output end of the signal synthesis circuit; the first feedback PMOS tube and the second feedback PMOS tube are respectively controlled to be turned on or off according to the output signals of the first comparing unit, the second comparing unit and the feedback state determining circuit, and the corresponding first type feedback signal, second type feedback signal or third type feedback signal is generated at the drain electrode of the corresponding feedback PMOS tube.

[0020] Based on the above technical solution, the beneficial effects of the present invention are:

[0021] The present invention provides a novel isolated power supply, in which the power transmission state and feedback state of the system are designed to be performed alternately, so that the power transmission from the primary circuit to the secondary circuit and the signal feedback from the secondary circuit to the primary circuit can use the same isolation transformer, and the output voltage can be stabilized under different load conditions and input voltage conditions; at the same time, the control mode of the present invention can reduce the power switching frequency under light load, so that the light load operation maintains high conversion efficiency; and in applications such as isolated switching power supplies, based on the present invention, the need for additional signal isolation devices can be eliminated, further improving the power density. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of a traditional isolated power supply in the prior art.

[0023] Figure 2 This is a schematic diagram of the structure of the isolated power supply provided by the present invention.

[0024] Figure 3 This is a schematic diagram of the structure of the feedback circuit in the isolated power supply provided by the present invention.

[0025] Figure 4 This is a schematic diagram of the structure of a control circuit in an isolated power supply provided by the present invention.

[0026] Figure 5 FIG. 4 is a circuit schematic diagram of an isolated voltage converter according to the present invention.

[0027] Figure 6 1 is a voltage and current waveform diagram of the isolated voltage converter based on the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0029] This embodiment provides a new type of isolated power supply, such as Figure 2 As shown, it specifically includes: an isolation transformer, a power transmission circuit and a control circuit located on the primary side of the isolation transformer, a rectifier circuit and a feedback circuit located on the secondary side of the isolation transformer, and the isolated power supply includes a power transmission state and a feedback state.

[0030] Power transmission state: The control circuit controls the power transmission circuit to be in working state. The power transmission circuit converts the primary input voltage into alternating voltage and drives the isolation transformer. The isolation transformer transmits the primary alternating voltage to the secondary side to form the secondary alternating voltage. The rectifier circuit converts the secondary alternating voltage into a DC voltage as the secondary output voltage. The control circuit monitors the duration of the power transmission state. The feedback circuit is in standby state and keeps monitoring the secondary voltage of the isolation transformer to determine the state of the power transmission circuit.

[0031] Feedback state: The control circuit controls the power transmission circuit to be in a dormant state, and the power transmission circuit outputs high impedance; the feedback circuit is in a working state, and generates a secondary feedback signal according to information such as the secondary DC output voltage, and transmits the secondary feedback signal to the secondary side of the isolation transformer. The isolation transformer transmits the secondary feedback signal to the primary side to form a primary feedback signal. The feedback circuit simultaneously keeps monitoring the secondary voltage of the isolation transformer to determine the state of the power transmission circuit; the control circuit monitors the duration of the feedback state, and keeps monitoring the primary voltage of the isolation transformer to receive the primary feedback signal;

[0032] The power transmission state is switched to the feedback state: the control circuit monitors the duration of the power transmission state. After reaching the first set duration, the control circuit controls the power transmission circuit to enter the sleep state, and the power transmission circuit outputs high impedance; after the feedback circuit determines that the power transmission circuit is in the sleep state by monitoring the secondary voltage of the isolation transformer, the feedback circuit enters the working state and enters the feedback state;

[0033] The feedback state is switched to the power transmission state: the control circuit monitors the duration of the feedback state and receives the primary feedback signal. When the primary feedback signal is a first type of feedback signal and the duration of the feedback state reaches a second set duration, the control circuit controls the power transmission circuit to enter the working state. When the primary feedback signal is a first type of feedback signal and the duration of the feedback state does not reach the second set duration, the control circuit controls the power transmission circuit to remain in the sleep state. When the primary feedback signal is a second type of feedback signal, the control circuit controls the power transmission circuit to remain in the sleep state. When the primary feedback signal is a third type of feedback signal, the control circuit controls the power transmission circuit to enter the working state. After the feedback circuit determines that the power transmission circuit is in the working state by monitoring the secondary voltage of the isolation transformer, the feedback circuit enters the standby state.

[0034] In an optional embodiment, the period of the alternating voltage is t 1 , the first set time length is the alternating voltage period t 1 n 1 times, the second set time length is the alternating voltage cycle t 1 n 2 times; optional, n 1 The value range of n is 10 to 20. 2 The value range is 2 to 3.

[0035] In an optional embodiment, the first input port of the power transmission circuit is coupled to the first port of the input voltage, the second input port of the power transmission circuit is coupled to the second port of the input voltage, the third input port of the power transmission circuit is coupled to the output end of the control circuit, the first output port of the power transmission circuit is coupled to the first port of the primary winding of the isolation transformer, and the second output port of the power transmission circuit is coupled to the second port of the primary winding of the isolation transformer; the first input port of the control circuit is coupled to the first port of the primary winding of the isolation transformer, and the second input port of the control circuit is coupled to the second port of the primary winding of the isolation transformer; the first input port of the rectifier circuit is coupled to the first port of the secondary winding of the isolation transformer, the second input port of the rectifier circuit is coupled to the second port of the secondary winding of the isolation transformer, the first output port of the rectifier circuit is coupled to the positive pole of the DC output voltage, and the second output port of the rectifier circuit is coupled to the negative pole of the DC output voltage; the first input port of the feedback circuit is coupled to the positive pole of the DC output voltage, the second input port of the feedback circuit is coupled to the negative pole of the DC output voltage, the third input port and the first output port of the feedback circuit are coupled to the first port of the secondary winding of the isolation transformer, and the fourth input port and the second output port of the feedback circuit are coupled to the second port of the secondary winding of the isolation transformer.

[0036] In an optional embodiment, the feedback circuit is as follows: Figure 3As shown, it includes: a voltage sampling circuit, a first comparison unit, a second comparison unit, a feedback state determination circuit, and a signal synthesis circuit; the first input port of the voltage sampling circuit is coupled to the positive pole of the DC output voltage, the second input port of the voltage sampling circuit is coupled to the negative pole of the DC output voltage, and the output end of the voltage sampling circuit is coupled to the positive input end of the first comparison unit and the reverse input end of the second comparison unit; the reverse input end of the first comparison unit is coupled to the first reference voltage, the output end of the first comparison unit is coupled to the first input port of the signal synthesis circuit, the positive input end of the second comparison unit is coupled to the second reference voltage, and the output end of the second comparison unit is coupled to the second input port of the signal synthesis circuit; the first input port of the feedback state determination circuit is coupled to the first input signal, the second input port of the feedback state determination circuit is coupled to the second input signal, and the output port of the feedback state determination circuit is coupled to the third input port of the signal synthesis circuit; the first output end of the signal synthesis circuit is coupled to the first secondary feedback signal output end, and the first output end of the signal synthesis circuit is coupled to the second secondary feedback signal output end;

[0037] The feedback circuit generates a corresponding secondary feedback signal according to the DC output voltage, the first input signal, and the second input signal, wherein the feedback state determination circuit determines whether to enter the feedback state according to the feedback state input signal. When the system enters the feedback state, the first comparison unit compares the output sampling voltage and the first reference voltage. If the output sampling voltage is less than the first reference voltage within the second set time, the signal synthesis circuit generates a first type of feedback signal, and the system enters the power transmission state; if the output sampling voltage is greater than the first reference voltage within the second set time, the signal synthesis circuit generates a second type of feedback signal, and the system maintains the feedback state; after the signal synthesis circuit generates the second type of feedback signal once, the second comparator compares the output sampling voltage and the second reference voltage. If the output sampling voltage is less than the second reference voltage, the signal synthesis circuit generates a third type of feedback signal, and the system enters the power transmission state; to be more precise: the feedback circuit can only generate a third type of feedback signal as a secondary feedback signal once after generating a second type of feedback signal as a secondary feedback signal;

[0038] Furthermore, the first type of feedback signal is a low level signal, the second type of feedback signal is a high level single pulse signal, and the third type of feedback signal is a high level single pulse signal; and the first reference voltage is greater than the second reference voltage.

[0039] Furthermore, the first input signal of the feedback state determination circuit is coupled to the first port of the secondary winding of the isolation transformer, and the second input signal of the feedback state determination circuit is coupled to the second port of the secondary winding of the isolation transformer; when the time length of the voltage difference between the first input signal and the second input signal being less than the first voltage threshold exceeds the first time threshold, the feedback circuit determines to enter the feedback state, otherwise it does not enter the feedback state; preferably, the first voltage threshold should be less than one-fifth of the amplitude of the alternating voltage on the secondary winding of the isolation transformer, and the first time threshold should be greater than the alternating voltage period t on the secondary winding. 1 One half of .

[0040] Furthermore, the signal synthesis circuit includes: a pulse signal generating circuit, a first feedback PMOS tube and a second feedback PMOS tube, the first input port, the second input port and the third input port of the pulse signal generating circuit are respectively coupled to the first input port, the second input port and the third input port of the signal synthesis circuit, the first output end of the pulse signal generating circuit is coupled to the gate of the first feedback PMOS tube, the second output end of the pulse signal generating circuit is coupled to the gate of the second feedback PMOS tube, the source of the first feedback PMOS tube and the second feedback PMOS tube are coupled to the DC output voltage, the drain of the first feedback PMOS tube is coupled to the first secondary side feedback signal output end, and the drain of the second feedback PMOS tube is coupled to the second secondary side feedback signal output end.

[0041] The pulse signal generating circuit controls the opening and closing of the first feedback PMOS tube and the second feedback PMOS tube respectively according to the output terminal signals of the first comparing unit, the second comparing unit and the feedback state determining circuit, and then generates corresponding first type feedback signals, second type feedback signals and third type feedback signals at the drains of the corresponding feedback PMOS tubes as secondary side feedback signals.

[0042] In an optional embodiment, the control circuit is as follows Figure 4 As shown, it includes: a third comparison unit, a fourth comparison unit, an oscillation circuit, a counting circuit, and a control signal generating circuit, wherein the inverting input terminal of the third comparison unit is coupled to the third reference voltage, the positive input terminal of the third comparison unit is coupled to the first primary feedback signal input terminal, and the output terminal of the third comparison unit is coupled to the first input port of the control signal generating circuit; the inverting input terminal of the fourth comparison unit is coupled to the fourth reference voltage, the positive input terminal of the fourth comparison unit is coupled to the second primary feedback signal input terminal, and the output terminal of the fourth comparison unit is coupled to the second input port of the control signal generating circuit; the output terminal of the oscillation circuit is coupled to the input terminal of the counting circuit, and the input terminal of the counting circuit is coupled to the third input port of the control signal generating circuit; the output port of the control signal generating circuit generates a control signal;

[0043] The oscillation circuit and the counting circuit are used to monitor the duration of the power transmission state and the duration of the feedback state, and the third comparison unit and the fourth comparison unit receive the primary feedback signal to switch the working state of the control signal generation circuit, thereby controlling the working state of the power transmission circuit; wherein, the oscillation circuit generates a system clock, the counting circuit generates a first set time length and a second set time length according to the system clock, and the control signal generation circuit generates a corresponding control signal according to the first set time length and the second set time length; in the power transmission state, within the first set time length, the control signal generation circuit controls the power transmission circuit to be in the power transmission state; in the feedback state, the third comparison unit and the fourth comparison unit compare, if the first primary feedback signal is greater than the third reference voltage an odd number of times or the second primary feedback signal is greater than the fourth reference voltage an odd number of times, then the control signal generation circuit controls the power transmission circuit to remain in the dormant state; if the first primary feedback signal is greater than the third reference voltage an even number of times or the second primary feedback signal input terminal is greater than the fourth reference voltage an even number of times, then the control signal generation circuit controls the power transmission circuit to enter the power transmission state;

[0044] Furthermore, the first primary feedback signal input terminal is coupled to the first port of the primary winding of the isolation transformer, and the second primary feedback signal input terminal is coupled to the second port of the primary winding of the isolation transformer; the first secondary feedback signal output terminal is coupled to the first port of the secondary winding of the isolation transformer, and the second secondary feedback signal output terminal is coupled to the second port of the secondary winding of the isolation transformer.

[0045] Furthermore, the third reference voltage is equal to the fourth reference voltage.

[0046] Specifically, this embodiment provides an isolated voltage converter based on the above-mentioned isolated power supply, such as Figure 5 As shown, it consists of a power transmission circuit, a control circuit, a rectification circuit, a feedback circuit and a load;

[0047] The power transmission circuit comprises: a PMOS-type first MOS transistor P1, a PMOS-type second MOS transistor P2, an NMOS-type third MOS transistor N1, an NMOS-type fourth MOS transistor N2, and a drive signal generating circuit; the source electrodes of the first MOS transistor and the second MOS transistor are coupled to the positive electrode of the DC power supply voltage, the source electrodes of the third MOS transistor and the fourth MOS transistor are coupled to the negative electrode of the DC power supply voltage, the drain electrodes of the first MOS transistor and the third MOS transistor are coupled to the first end of the primary winding of the transformer, and the drain electrodes of the third MOS transistor and the fourth MOS transistor are coupled to the second end of the primary winding of the transformer; the gate electrodes of the first MOS transistor, the second MOS transistor, the third MOS transistor, and the fourth MOS transistor are connected to the drive signal from the drive signal generating circuit; optionally, the control signal set in the embodiment enables the first MOS transistor, the fourth MOS transistor, the second MOS transistor, and the third MOS transistor to be alternately turned on, the voltage at both ends of the primary winding of the transformer alternately changes between +VDD and -VDD over time, and the secondary winding generates an alternating voltage as the input voltage of the rectifier circuit;

[0048] The rectifier circuit comprises: a PMOS type fifth MOS tube P1, a PMOS type sixth MOS tube P2, an NMOS type seventh MOS tube N1, an NMOS type eighth MOS tube N2, and a rectifier driving circuit; the source electrodes of the fifth MOS tube and the sixth MOS tube are coupled to the positive electrode of the DC output voltage, the source electrodes of the seventh MOS tube and the eighth MOS tube are coupled to the negative electrode of the DC output voltage, the drain electrodes of the fifth MOS tube and the seventh MOS tube are coupled to the first end of the secondary winding of the transformer, and the drain electrodes of the sixth MOS tube and the eighth MOS tube are coupled to the second end of the primary winding of the transformer; the gate electrodes of the fifth MOS tube, the sixth MOS tube, the seventh MOS tube, and the eighth MOS tube are connected to the driving signal from the rectifier driving circuit; the driving signal of the rectifier driving circuit should enable the fifth (or sixth) MOS tube to be turned on when the drain voltage of the fifth (or sixth) MOS tube is greater than the source voltage, otherwise the fifth (or sixth) MOS tube is turned off; the seventh (or eighth) MOS tube is turned on when the source voltage of the seventh (or eighth) MOS tube is greater than the drain voltage, otherwise the seventh (or eighth) MOS tube is turned off, so as to realize its rectification function;

[0049] Optionally, the feedback circuit in the embodiment is composed of Figure 3 The feedback circuit described above is composed of the control circuit in the embodiment. Figure 4 The control circuit described is constructed.

[0050] like Figure 6 As shown, it is the voltage and current waveform diagram of this embodiment. It can be seen that the isolated voltage converter realizes the voltage stabilization of the DC output voltage, and the voltage stabilization feedback control is completed by the secondary circuit sending a feedback signal to the primary circuit through the isolation transformer that transmits power, without the need for additional signal isolation devices.

[0051] The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other alternative features that are equivalent or have similar purposes; all the disclosed features, or all the steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A new type of isolated power supply, comprising: An isolation transformer, a power transmission circuit and a control circuit located on the primary side of the isolation transformer, and a rectification circuit and a feedback circuit located on the secondary side of the isolation transformer; characterized in that: The isolated power supply includes a power transmission state and a feedback state, and the power transmission state and the feedback state are performed alternately; The control circuit controls the power transmission circuit to be in a power transmission state, and the feedback circuit is in a standby state; the power transmission circuit converts the input voltage into an alternating voltage, drives the isolation transformer, the isolation transformer transmits the primary side alternating voltage to the secondary side to form a secondary side alternating voltage, and the rectifier circuit converts the secondary side alternating voltage into a DC voltage as a secondary side output voltage; The control circuit monitors the duration of the power transmission state, and when the set duration is reached, the control circuit controls the power transmission circuit to enter the sleep state; The feedback circuit monitors the voltage on the secondary side of the isolation transformer. When it is determined that the power transmission circuit enters a dormant state, the feedback circuit enters a feedback state, generates a secondary side feedback signal, and transmits the secondary side feedback signal to the secondary side of the isolation transformer. The isolation transformer transmits the secondary side feedback signal to the primary side to form a primary side feedback signal. The control circuit receives the primary feedback signal and monitors the duration of the feedback state; the control circuit adjusts the power transmission circuit according to the primary feedback signal and the duration information of the feedback state, and controls the power transmission circuit to maintain the sleep state or enter the power transmission state again.

2. The isolated power supply according to claim 1, characterized in that: The first input port of the power transmission circuit is coupled to the first port of the input voltage, the second input port of the power transmission circuit is coupled to the second port of the input voltage, the third input port of the power transmission circuit is coupled to the output end of the control circuit, the first output port of the power transmission circuit is coupled to the first port of the primary winding of the isolation transformer, and the second output port of the power transmission circuit is coupled to the second port of the primary winding of the isolation transformer; the first input port of the control circuit is coupled to the first port of the primary winding of the isolation transformer, and the second input port of the control circuit is coupled to the second port of the primary winding of the isolation transformer; the first input port of the rectifier circuit is coupled to the first port of the secondary winding of the isolation transformer, the second input port of the rectifier circuit is coupled to the second port of the secondary winding of the isolation transformer, the first output port of the rectifier circuit is coupled to the positive pole of the DC output voltage, and the second output port of the rectifier circuit is coupled to the negative pole of the DC output voltage; the first input port of the feedback circuit is coupled to the positive pole of the DC output voltage, the second input port of the feedback circuit is coupled to the negative pole of the DC output voltage, the third input port and the first output port of the feedback circuit are coupled to the first port of the secondary winding of the isolation transformer, and the fourth input port and the second output port of the feedback circuit are coupled to the second port of the secondary winding of the isolation transformer.

3. The isolated power supply according to claim 2, characterized in that: The control circuit includes: a third comparison unit, a fourth comparison unit, an oscillation circuit, a counting circuit, and a control signal generating circuit. The inverting input terminal of the third comparison unit is coupled to a third reference voltage, the positive input terminal of the third comparison unit serves as a first input port of the control circuit and receives a first primary feedback signal, and the output terminal of the third comparison unit is coupled to the first input port of the control signal generating circuit; the inverting input terminal of the fourth comparison unit is coupled to a fourth reference voltage, the positive input terminal of the fourth comparison unit serves as a second input port of the control circuit and receives a second primary feedback signal, and the output terminal of the fourth comparison unit is coupled to the second input port of the control signal generating circuit; the output terminal of the oscillation circuit is coupled to the input terminal of the counting circuit, and the input terminal of the counting circuit is coupled to the third input port of the control signal generating circuit; the output port of the control signal generating circuit serves as the output terminal of the control circuit and outputs a control signal.

4. The isolated power supply according to claim 3, characterized in that: The oscillation circuit and the counting circuit are used to monitor the duration of the power transmission state and the duration of the feedback state, and the third comparison unit and the fourth comparison unit receive the primary feedback signal; wherein, the oscillation circuit generates a system clock, the counting circuit generates a first set duration and a second set duration according to the system clock, and the control signal generation circuit generates a corresponding control signal according to the first set duration and the second set duration; in the power transmission state, within the first set duration, the control signal generation circuit controls the power transmission circuit to be in the power transmission state; in the feedback state, the third comparison unit and the fourth comparison unit compare, and within the second set duration, if the first primary feedback signal is greater than the third reference voltage an odd number of times or the second primary feedback signal is greater than the fourth reference voltage an odd number of times, the control signal generation circuit controls the power transmission circuit to remain in the dormant state; if the first primary feedback signal is greater than the third reference voltage an even number of times or the second primary feedback signal input terminal is greater than the fourth reference voltage an even number of times, the control signal generation circuit controls the power transmission circuit to enter the power transmission state.

5. The isolated power supply according to claim 4, characterized in that: The period of the alternating voltage is t1, the first set time length is n1 times of the alternating voltage period t1, and the second set time length is n2 times of the alternating voltage period t1; the value range of n1 is 10 to 20, and the value range of n2 is 2 to 3.

6. The isolated power supply according to claim 2, characterized in that: The feedback circuit includes: a voltage sampling circuit, a first comparison unit, a second comparison unit, a feedback state determination circuit, and a signal synthesis circuit; the first input port of the voltage sampling circuit is coupled to the positive pole of the DC output voltage, the second input port of the voltage sampling circuit is coupled to the negative pole of the DC output voltage, and the output end of the voltage sampling circuit is coupled to the positive input end of the first comparison unit and the negative input end of the second comparison unit; the negative input end of the first comparison unit is coupled to the first reference voltage, the output end of the first comparison unit is coupled to the first input port of the signal synthesis circuit, the positive input end of the second comparison unit is coupled to the second reference voltage, and the output end of the second comparison unit is coupled to the second input port of the signal synthesis circuit; the first input port of the feedback state determination circuit is coupled as the third input port of the feedback circuit and inputs the first input signal, the second input port of the feedback state determination circuit is coupled as the fourth input port of the feedback circuit and inputs the second input signal, and the output port of the feedback state determination circuit is coupled to the third input port of the signal synthesis circuit; the first output end of the signal synthesis circuit is used as the first output port of the feedback circuit and outputs the first secondary feedback signal, and the first output end of the signal synthesis circuit is used as the second output port of the feedback circuit and outputs the second secondary feedback signal.

7. The isolated power supply according to claim 6, characterized in that: In the feedback circuit, the feedback state determination circuit monitors the secondary voltage of the isolation transformer, and when the time length of the voltage difference between the first input signal and the second input signal being less than the first voltage threshold exceeds the first time threshold, it is determined that the power transmission circuit enters the dormant state, and the feedback circuit enters the feedback state; The first comparison unit compares the output sampling voltage and the first reference voltage. If the output sampling voltage is less than the first reference voltage within a second set time, the signal synthesis circuit generates a first type of feedback signal; if the output sampling voltage is greater than the first reference voltage within the second set time, the signal synthesis circuit generates a second type of feedback signal, and after the signal synthesis circuit generates the second type of feedback signal once, the second comparator compares the output sampling voltage and the second reference voltage. If the output sampling voltage is less than the second reference voltage, the signal synthesis circuit generates a third type of feedback signal; the first type of feedback signal is a low-level signal, the second type of feedback signal is a high-level single pulse signal, and the third type of feedback signal is a high-level single pulse signal.

8. The isolated power supply according to claim 7, characterized in that: The first voltage threshold should be less than one fifth of the amplitude of the alternating voltage on the secondary winding of the isolation transformer, and the first time threshold should be greater than one half of the alternating voltage period t1 on the secondary winding.

9. The isolated power supply according to claim 6, characterized in that: The signal synthesis circuit comprises: a pulse signal generating circuit, a first feedback PMOS tube and a second feedback PMOS tube, wherein the first input port, the second input port and the third input port of the pulse signal generating circuit are respectively used as the first input port, the second input port and the third input port of the signal synthesis circuit, the first output end of the pulse signal generating circuit is coupled to the gate of the first feedback PMOS tube, the second output end of the pulse signal generating circuit is coupled to the gate of the second feedback PMOS tube, the source electrodes of the first feedback PMOS tube and the second feedback PMOS tube are coupled to a direct current output voltage, the drain electrode of the first feedback PMOS tube is used as the first output end of the signal synthesis circuit, and the drain electrode of the second feedback PMOS tube is used as the second output end of the signal synthesis circuit; the first feedback PMOS tube and the second feedback PMOS tube are respectively controlled to be turned on or off according to the output signals of the first comparing unit, the second comparing unit and the feedback state determining circuit, and the corresponding first type feedback signal, second type feedback signal or third type feedback signal is generated at the drain electrode of the corresponding feedback PMOS tube.

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