Isolated power supply system and wireless modulation device and method for PWM control

Abstract

The invention provides an isolated power supply system and a wireless modulation device and method for PWM control, and is applied to the technical field of PWM and isolated power supplies, in the isolated power supply system based on PWM, on the basis that a power transformer can transmit a power signal, a low-frequency PWM signal used for power modulation is used as a switching signal, and the switching signal is used as a switching signal. And a part of the secondary side power inductor is taken to form resonance, a high-frequency signal is generated after resonance to realize PWM modulation and is transmitted through an isolated gate, and finally, the signal can be restored by using a corresponding decoding circuit of the primary side to complete modulation transmission of the PWM signal. Power and signal transmission is achieved through the same power transformer, an additional digital transformer / isolation capacitor is not needed, an additional bias module, an oscillator and the like are not needed, the circuit structure is simplified, and the cost and the chip area are effectively reduced.

Description

Technical Field

[0001] The present application relates to the technical fields of PWM signal modulation and isolated power supply, and particularly relates to an isolated power supply system, a wireless modulation device and method for PWM control. Background Art

[0002] In an isolated power supply / wireless charging system, power is transmitted through a transformer, and the control stage often uses PWM control to achieve load modulation of the circuit. PWM control adjusts the output voltage V by turning on / off an LC resonant oscillator ISO , and there is voltage isolation between the primary and secondary sides. Therefore, modulation signals often require an additional feedback channel, such as a digital transformer or an isolation capacitor. At the same time, relatively low-frequency PWM signals (about 500 kHz) cannot be directly transmitted to the transmitting chip through the digital transformer / capacitor. The digital isolator circuit is responsible for encoding and decoding the feedback signal at both ends of the on-chip transformer / capacitor to achieve the transmission of PWM signals with different duty cycles to adjust the average input power and ensure the stability of the output voltage.

[0003] Therefore, the transmission of PWM signals not only requires complex encoding and decoding circuits to ensure the reliability of the signal channel, but also requires additional on-chip digital transformers or isolation capacitors as isolation channels, which greatly increases the cost and design complexity of the chip. Summary of the Invention

[0004] In view of this, the present application provides an isolated power supply system, a wireless modulation device and method for PWM control, which can complete signal transmission based on a power inductor, eliminate the need for an additional isolation channel, simplify the design and reduce costs.

[0005] The present application provides the following technical solutions:

[0006] The present application provides a wireless modulation device for PWM control, including:

[0007] A power transformer: a transformer composed of a primary coil and a secondary coil, serving as an isolation medium for power and signal isolation transmission; wherein, the primary coil includes a primary power transmission port and a primary signal transmission port, the secondary coil includes a secondary power transmission port and a secondary signal transmission port, the primary signal transmission port is a two-terminal port formed by taking a part of the inductance in the primary coil and leading it out, the secondary signal transmission port is a two-terminal port formed by taking a part of the inductance in the secondary coil and leading it out, the power signal realizes power transmission from the primary coil to the secondary coil through the primary power transmission port to the secondary power transmission port, and the PWM signal realizes feedback signal transmission from the secondary coil to the primary coil through the secondary signal transmission port to the primary signal transmission port;

[0008] Resonant circuit: It includes a PWM control signal input port, two resonant ports, and a resonant loop; wherein, the two resonant ports are connected to the secondary side signal transmission port; the PWM control signal input port is used to input the PWM signal to be modulated; the resonant loop is used to form a new resonant unit with a part of the inductance taken from the secondary coil in the secondary side signal transmission port, so as to resonate a preset high-frequency signal under the control of the PWM signal, realizing the wireless modulation transmission of the PWM signal from the secondary coil side to the primary coil side, and the connection between the two resonant ports of the resonant loop and the secondary side signal transmission port is controlled by the PWM signal: when the PWM signal is valid, the connection between the two resonant ports of the resonant loop and the secondary side signal transmission port is connected, and when the PWM signal is invalid, the connection between the two resonant ports of the resonant loop and the secondary side signal transmission port is cut off.

[0009] Preferably, the resonant loop includes a first capacitor, a second capacitor, a switch, a first transistor, a second transistor, a third transistor, and a fourth transistor; wherein, one end of the first capacitor and one end of the second capacitor respectively serve as the two resonant ports; the other end of the first capacitor is connected to the drain of the first transistor, the drain of the third transistor, and the gate of the fourth transistor; the other end of the second capacitor is connected to one end of the switch; the other end of the switch is connected to the drain of the second transistor, the gate of the third transistor, and the drain of the fourth transistor; the source of the first transistor and the source of the second transistor are both connected to the power supply terminal; the source of the third transistor and the source of the fourth transistor are both connected to the ground; the control end of the switch serves as the control signal input port.

[0010] Preferably, the first capacitor and / or the second capacitor is an on-chip capacitor;

[0011] And / or, the switch is a MOS transistor switch.

[0012] Preferably, the first capacitor and / or the second capacitor and the switch are integrally designed on the same chip;

[0013] And / or, the first capacitor and / or the second capacitor and one or more of the following transistors are integrally designed on the same chip: the first transistor, the second transistor, the third transistor, the fourth transistor.

[0014] Preferably, the frequency of the high-frequency signal is determined by the following parameters: the inductance value of a part of the inductance taken from the secondary coil in the secondary side signal transmission port, the first capacitor, the second capacitor, and the transistor sizes of the first transistor to the fourth transistor; and, the signal amplitude depends on the voltage value of the power supply terminal and the transistor sizes of the first transistor to the fourth transistor.

[0015] Preferably, the frequency of the high-frequency signal is approximately calculated as:

[0016]

[0017] Among them, L is the inductance value of a part of the inductance taken from the secondary coil in the secondary-side signal transmission port, and C is the capacitance value of the first capacitor and the second capacitor.

[0018] Preferably, the wireless modulation device for PWM control described in any item of the present application is used to replace the isolation gate in the isolation power supply system based on PWM control.

[0019] The present application also provides a wireless modulation method for PWM control, including:

[0020] Input the PWM signal into the PWM control signal input port, where the PWM control signal input port is the PWM control signal input port provided in the wireless modulation device for PWM control described in any item of the present application;

[0021] Based on the power transformer, realize the power transmission from the primary coil to the secondary coil of the power signal, and based on the resonant circuit and a part of the inductance taken from the secondary coil in the secondary-side signal transmission port, resonate the PWM signal to a preset high-frequency signal, and realize the feedback signal transmission from the secondary coil to the primary coil; among them, the power transformer and the resonant circuit are the power transformer and the resonant circuit provided in the wireless modulation for PWM control described in any item of the present application.

[0022] Preferably, the frequency of the high-frequency signal obtained by resonance is approximately calculated in the following way: determined according to the inductance value of a part of the inductance taken from the secondary coil in the secondary-side signal transmission port and / or the capacitance value of the first capacitor and the second capacitor in the resonant circuit, where the frequency of the high-frequency signal is:

[0023]

[0024] Among them, L is the inductance value of a part of the inductance taken from the secondary coil in the secondary-side signal transmission port, and C is the capacitance value of the first capacitor and the second capacitor.

[0025] The present application also provides an isolation power supply system based on PWM control, including an inverter circuit, a rectifier circuit, an isolation gate, a PWM encoding circuit, and a PWM decoding circuit, where the isolation gate includes a power transformer provided by the wireless modulation device for PWM control described in any item of the present application; the PWM encoding circuit includes a feedback circuit and a resonant circuit, where the resonant circuit includes the resonant circuit provided by the wireless modulation device for PWM control described in any item of the present application;

[0026] Among them, the primary power transmission port of the power transformer is electrically connected to the inverter circuit, the secondary power transmission port is connected to the rectifier circuit, the primary signal transmission port is electrically connected to the PWM decoding circuit, the secondary signal transmission port is connected to the resonant circuit, and the PWM control signal input port of the resonant circuit is electrically connected to the feedback circuit;

[0027] The feedback circuit is used to sample the output voltage of the rectifier circuit and generate a low-frequency PWM control signal with a corresponding frequency; the PWM decoding circuit is used to recover the low-frequency PWM signal from the high-frequency signal output from the primary signal transmission port; the inverter circuit is used to convert the input DC voltage into an AC power signal according to the PWM signal output by the PWM decoding circuit; the power transformer is used for power signal and high-frequency signal transmission; the rectifier circuit is used to convert the power signal from the power transformer into a DC output voltage.

[0028] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted in this application at least include:

[0029] Compared with the traditional digital signal transmission implementation method, the present invention forms a PWM signal modulation isolation transmission through a power transformer and a resonant circuit, and has the following advantages:

[0030] (1) Signal transmission is carried out through a power transformer, without an additional digital isolation gate, greatly reducing the cost and area.

[0031] (2) The coding circuit is simple and does not require a bias circuit, an oscillator circuit, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 is a functional block diagram of a traditional isolated power supply system;

[0034] Figure 2 is a schematic structural diagram of a wireless transmission implementation of an isolated power supply system based on PWM control in the present application;

[0035] Figure 3 is a schematic waveform diagram of key nodes of wireless signal transmission in the present application;

[0036] Figure 4 is a schematic diagram of a resonant structure composed of capacitors and switches for wireless transmission implementation of an isolated power supply system based on PWM control in the present application. Detailed implementation mode

[0037] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0038] The following uses specific specific examples to illustrate the implementation mode of the present application. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation modes. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative work belong to the scope of protection of the present application.

[0039] It should be noted that the following description relates to various aspects of embodiments within the scope of the appended claims. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is illustrative only. Based on the present application, those skilled in the art should understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects described herein can be used to implement the device and / or practice the method. Additionally, this device and / or this method can be implemented using other structures and / or functionality in addition to one or more of the aspects described herein.

[0040] It should also be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present application in a schematic manner. The diagrams only show the components related to the present application, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in its actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0041] In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the examples can be practiced without these specific details.

[0042] The functional block diagram of the isolated power supply system is as shown in the appendix Figure 1 shown. The transmitting chip is used to invert the input power supply VDD into an AC power signal to drive the transformer. The transformer chip includes a power transformer and a digital isolation capacitor, which respectively act as the isolation gate of the system to achieve power transmission and control signal feedback. The receiving chip rectifies the received AC power signal into a stable DC output voltage. In the signal transmission channel, by SiO2 The high-voltage isolation capacitor formed provides an insulation barrier between different voltage domains and provides a high-frequency signal transmission path; for the isolated transmission of PWM signals, an encoding circuit and a decoding circuit are required to achieve isolated feedback transmission. The commonly used feedback digital channel scheme is the OOK on-off keying modulation scheme. The principle is that the transmitter (TX) modulates the input signal onto the carrier frequency, that is, the TX transmits a high-frequency signal through the isolation capacitor in one input state, and no signal passes through the isolation capacitor in another input state. Then the receiver reconstructs the input signal based on the detected in-band data. It can be seen that the signal transmission of this scheme highly depends on an additional isolation capacitor. That is, in the isolated power supply system, in order to perform load modulation, an additional isolation channel needs to be added, which not only increases the cost but also is not conducive to the miniaturized design of the chip.

[0043] In view of this, through in-depth research and improvement exploration of the isolated power supply system and its modulation method, it is found that:

[0044] On the one hand, a transformer can achieve isolated energy transmission between the primary side and the secondary side, so a power transformer is a common component in the isolated power supply system. Therefore, if the power transformer can be used to transmit the feedback signal from the secondary side to the primary side, the isolated transmission of the feedback signal should no longer require a digital isolation capacitor.

[0045] On the other hand, in an isolated power supply system based on PWM (pulse width modulation) control, during the process of the power transformer transmitting power energy, there is always energy on the secondary side power inductor L S Therefore, if resonance can be carried out using a small amount of power energy to complete the high-frequency modulation of the PWM signal when the feedback signal is transmitted from the secondary side to the primary side based on the power transformer, a complex and expensive PWM encoding circuit can be avoided.

[0046] As Figure 2 shown, the present invention proposes an isolated power supply system and a wireless modulation transmission scheme for PWM control:

[0047] On the one hand, the isolation chip (which can also be called an isolator, isolation circuit, isolation gate, etc., without distinction) in the isolated power supply system is improved to an isolation gate form that only contains the power transformer 200 for power transmission, and the power transformer 200 is improved to the following new structural form, that is, the power transformer 200 includes: the primary side power transmission ports V PP 、V PN , which are used to connect the inverter circuit 100 on the transmitter chip side; the secondary side power transmission ports V SP 、V SN , which are used to connect the rectifier circuit 300 on the receiver chip side; and the primary side signal transmission ports V PA 、V PB and the secondary side signal transmission ports V SA, V SB , respectively for connecting the decoding circuit 600 and for connecting the encoding circuit.

[0048] After the power transformer 200 is improved to a new isolation structure, since the power transformer 200 can not only realize the transmission of power energy from the primary side to the secondary side, but also realize the transmission of the PWM feedback signal from the secondary side to the primary side, the digital isolation capacitor required for the transmission of the feedback signal can no longer be provided in the isolation chip, which can simplify the design of the isolation gate and save the circuit area.

[0049] Second, for the need of PWM signal transmission, the PWM encoding circuit is improved to obtain a new encoding circuit, which may include: a resonant circuit 500 and a feedback circuit 400, wherein the resonant circuit 500 and the power transformer 200 form a new resonant unit, that is, in the isolated power supply system based on PWM control, a part of the inductance is taken out from the secondary power inductor Ls, and a new resonant frequency higher than the PWM frequency can be resonated with the newly added resonant circuit 500, so as to realize the transmission of the PWM feedback signal (that is, the feedback circuit 400 generates a low-frequency PWM signal according to the output voltage) from the secondary side to the primary side.

[0050] Among them, the low-frequency PWM signal used for power feedback modulation is used to connect or disconnect the secondary signal transmission port V of the resonant circuit 500 connected to the secondary power inductor Ls SA , V SB , so that when the resonant circuit 500 is connected, the resonant circuit 500 and a part of the inductance taken out from the secondary power inductor Ls form a new resonant unit, generating a high-frequency signal with a frequency higher than the PWM signal, so that the PWM feedback signal in the form of the high-frequency signal can reach the primary side through the isolation gate from the secondary side, and the decoding circuit 600 connected to the primary signal transmission port V PA , V PB restores the feedback signal.

[0051] In summary, the improved technical solution does not require an additional digital transformer / isolation capacitor, does not require an additional bias module, oscillator, etc., only needs to form corresponding signal transmission ports on the primary side and the secondary side of the power transformer respectively, and uses a small part of the inductance in the secondary inductor Ls and the newly added resonant circuit to reconstitute a new resonant unit, the principle is simple, and the circuit structure is simplified.

[0052] It should be noted that although the wireless modulation scheme example of the PWM signal in this application takes the PWM signal in the isolated power supply system as an example, other systems facing PWM control and requiring isolated transmission of the PWM signal can also use the device of this application to implement, that is, the isolated power supply system is an application example of the PWM signal wireless modulation scheme in this application, and other similar application scenarios can refer to the application mode of the PWM signal in the isolated power supply system.

[0053] The technical solutions provided by the embodiments of the present application will be described below with reference to the accompanying drawings.

[0054] The core idea of the present invention is to use the power transformer in the isolated power supply system as the signal transmission path, without adding additional digital isolation transformers / capacitors, which greatly reduces the chip area and packaging cost.

[0055] Refer to Figure 2 As shown, the present invention proposes an isolated power supply system, which mainly includes: an inverter circuit 100, a power transformer 200, a rectifier circuit 300, a feedback circuit 400, a resonance circuit 500, and a decoding circuit 600. It should be noted that the inverter circuit 100 and the rectifier circuit 300 can be the relevant circuits in the original solution or newly designed circuits, which are not limited here.

[0056] Next, in conjunction with Figure 3 the waveforms shown, the composition and functions of each circuit will be described:

[0057] Inverter circuit 100: It is used to invert the input DC voltage V DD into a differential high-frequency oscillating power signal V PP and V PN , and output them from the V PP and V PN ports to the primary coil L P of the micro-transformer 200;

[0058] Power transformer 200: It consists of a primary coil L P and a secondary coil L S , serves as an isolation medium and realizes the transmission of power from the primary to the secondary and the transmission of signals from the secondary to the primary;

[0059] Rectifier circuit 300: It is used to rectify the high-frequency oscillating signals received at the secondary ends V SP and V SN of the transformer 200 into DC signals and provide them to the output load;

[0060] Feedback circuit 400: It is used to sample the output voltage and generate low-frequency PWM signals with different duty cycles to keep the output voltage constant;

[0061] Resonance circuit 500: It is used to convert the low-frequency PWM signal into a high-frequency oscillating signal and output it from V SA , V SB externally;

[0062] Decoding circuit 600: It is used to decode the high-frequency oscillating signals from V PA , V PB and restore them to low-frequency PWM signals, which are fed back to the inverter circuit 100.

[0063] The power transformer 200 includes: a primary power transmission port V PP 、V PN for connecting to the inverter circuit 100; a secondary power transmission port V SP 、V SN for connecting to the rectifier circuit 300; a primary signal transmission port V PA 、V PB for connecting to the decoding circuit 600; a secondary signal transmission port V SA 、V SB for connecting to the encoding circuit, where the encoding circuit can be in the form of the circuit composed of the aforementioned resonant circuit 500 and the feedback circuit 400 to implement the modulation of the PWM signal (i.e., implement encoding).

[0064] Among them, V PA 、V PB are ports formed by taking out a part of the inductance from the primary coil, and V SP 、V SN are ports formed by taking out a part of the inductance from the secondary coil, and the two parts of the inductance are mutually coupled as an isolation channel for signal transmission.

[0065] Combined with Figure 2 and Figure 3 the schematic content, the working schematic of the overall circuit is as follows: The power signal is transmitted through the primary power transmission port V PP 、V PN and the secondary power transmission port V SP 、V SN ; After the PWM signal resonates to a high-frequency signal with a higher frequency, it is transmitted through the secondary signal transmission port V SA 、V SB and the primary signal transmission port V PA 、V PB to achieve signal transmission, and then the decoding circuit on the primary side decodes the high-frequency oscillation signal on V PA 、V PB to complete the feedback transmission of the PWM signal.

[0066] In addition, since the inductance between V SA 、V SB is only a part of the secondary inductance, and the resonant frequency needs to be distinguished from the power stage driving frequency and the chip ringing frequency, and the capacitance value of the on-chip resonant capacitor is very limited, so its oscillation amplitude can be ignored compared with the voltage between the power inductors V SP 、V SN , which does not affect the power transmission of the power stage and does not increase the output ripple.

[0067] From Figure 3From the key-node waveform diagram of the signal transmission shown, it can be seen that: PWM_S is a low-frequency signal output by the secondary-side feedback control module. When PWM_S is high, the resonant circuit operates, and V SP -V SN transmits a high-frequency signal to the primary side, the output PWM_P of the decoding circuit is translated to high, and the primary-side power stage alternately operates to transmit power; when PWM_S is low, the resonant circuit is turned off, the output PWM_P of the decoding circuit is translated to low, and the primary-side power stage is turned off.

[0068] In some examples, a preferred implementation of the resonant circuit 500 can refer to Figure 4 the schematic circuit shown, that is, the resonant circuit 500 can be simplified to the following circuit structure:

[0069] Refer to Figure 4 shown, the resonant circuit includes: a pair of PMOS transistors M P1 、M P2 , a pair of NMOS transistors M N1 、M N2 , a pair of coupling capacitors C1, C2 and a switch S1. Among them, the sources of M P1 、M P2 are connected to the power supply voltage VDD, and the sources of M N1 、M N2 are grounded to GND. The gates of the PMOS and NMOS transistors are all connected in a cross-coupled manner, that is, the gates of M P1 、M N1 are connected to the drains of M P2 、M N2 , and the gates of M P2 、M N2 are connected to the drains of M P1 、M N1 . The gates of M P2 、M N2 are connected to one end of the coupling capacitor C1, and the other end of C1 is used as the output V SA ; the gates of M P1 、M N1 are connected to one end of the switch S1, and the other end of S1 is connected to one end of the coupling capacitor C2, and the other end of C2 is used as the output V SB .

[0070] Therefore, the PWM signal is used as the control signal of S1, and is connected to / disconnected from the resonant circuit in an on / off manner to achieve signal encoding. Its main principle is: when the PWM signal is high, that is, the switch is closed, the inductor between V SA 、V SB will resonate with the resonant capacitors C1, C2 and the V GS of the MOS transistor.

[0071] To prevent the oscillation circuit from affecting the power transmission of the power stage, coupling capacitors C1 and C2 need to be added across the inductor between V SA and V SB to filter out the DC component.

[0072] In addition, the resonant frequency can be approximately calculated as follows:

[0073]

[0074] The frequency of this signal depends on the inductor between V SA and V SB , the resonant capacitors C1 and C2, and the size of the transistor. The signal amplitude depends on the magnitude of VDD and the size of the MOS transistor.

[0075] It should be noted that for an isolated power supply system using PWM control, when PWM is high, the power stage alternately charges and discharges the inductor at a fixed driving frequency. At this time, the high-frequency oscillation signal of the resonant circuit is superimposed on the oscillation signal of the power inductor; when PWM changes from high to low, the resonant circuit is disconnected and does not generate a high-frequency oscillation signal. At this time, the primary decoding circuit is low and the power stage is turned off to reduce power transmission; when PWM changes from low to high, the power stage needs to be restarted. S1 is closed, and the high-frequency oscillation signal generated by the resonant circuit under the power supply voltage can still be transmitted to the primary side through the isolation gate. The decoding circuit is high, and the power stage restarts and normally transmits power.

[0076] By reasonably setting the power supply voltage of the resonant circuit and the size of the MOS transistor, its oscillation amplitude can be negligible compared to the voltage between the power inductors V SP and V SN , which does not affect the power transmission of the power stage and does not increase the output ripple.

[0077] In summary, in an isolated power supply system based on PWM modulation, a part of the primary and secondary power inductors is used for modulating signal transmission. The high-frequency carrier signal generated by the secondary resonant circuit can pass through the isolation gate without affecting power transmission. This solution does not require an additional digital transformer / isolation capacitor, nor a complex bias module, oscillator, etc., greatly simplifying the chip design.

[0078] In some preferred examples, the first capacitor and / or the second capacitor in the resonant circuit are set as on-chip capacitors.

[0079] In some preferred examples, the switch is preferably an electronic switch composed of a transistor, such as a preferred MOS transistor. Specifically, a PMOS transistor or an NMOS transistor can be preferably selected according to the circuit design.

[0080] In some preferred examples, the first capacitor and / or the second capacitor and the switch can be integrally designed on the same chip, thereby forming a chip of the resonant circuit. When different resonant frequencies are required, the corresponding chip can be selected to resonate with the inductor of the power transformer.

[0081] In some preferred examples, the first capacitor and / or the second capacitor are integrally designed on the same chip with one or more of the following transistors: the first transistor (denoted as M P1 ), the second transistor (denoted as M P2 ), the third transistor (denoted as M N1 ), the fourth transistor (denoted as M N2 ).

[0082] In some preferred examples, according to the requirement of setting the resonant frequency, the frequency of the high-frequency signal can be determined by the following parameters: the inductance value of a part of the inductance taken from the secondary coil in the secondary-side signal transmission port, the sizes of the first capacitor, the second capacitor, and the first to fourth transistors; and, the signal amplitude depends on the voltage value of the power supply terminal and the sizes of the first to fourth transistors, and can be flexibly adapted to the selection requirements of different resonant frequencies.

[0083] In this specification, for the same and similar parts between various embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the embodiments described later, the description is relatively simple, and for the relevant parts, reference can be made to the partial description of the foregoing embodiments.

[0084] As described above, the above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A wireless modulation device for PWM control, characterized in that: include: Power transformer: A transformer consisting of a primary coil and a secondary coil, which serves as an isolation medium for power and signal isolation transmission; wherein the primary coil includes a primary power transmission port and a primary signal transmission port, and the secondary coil includes a secondary power transmission port and a secondary signal transmission port. The primary signal transmission port is a two-terminal port formed by a part of the inductance in the primary coil, and the secondary signal transmission port is a two-terminal port formed by a part of the inductance in the secondary coil. The power signal is transmitted from the primary coil to the secondary coil through the primary power transmission port to the secondary power transmission port, and the PWM signal is transmitted from the secondary coil to the primary coil through the secondary signal transmission port to the primary signal transmission port. Resonant circuit: comprising a PWM control signal input port, two resonant ports and a resonant loop; wherein the two resonant ports are connected to a secondary signal transmission port; the PWM control signal input port is used to input a PWM signal to be modulated; the resonant loop is used to form a new resonant unit with a part of the inductance taken from the secondary coil in the secondary signal transmission port, so as to resonate a preset high-frequency signal under the control of the PWM signal, thereby realizing wireless modulation transmission of the PWM signal from one side of the secondary coil to one side of the primary coil, wherein the connection between the two resonant ports of the resonant loop and the secondary signal transmission port is controlled by the PWM signal: when the PWM signal is valid, the connection between the two resonant ports of the resonant loop and the secondary signal transmission port is connected, and when the PWM signal is invalid, the connection between the two resonant ports of the resonant loop and the secondary signal transmission port is cut off.

2. The wireless modulation device for PWM control according to claim 1, characterized in that: The resonant circuit includes a first capacitor, a second capacitor, a switch, a first transistor, a second transistor, a third transistor and a fourth transistor; wherein one end of the first capacitor and one end of the second capacitor serve as the two resonant ports respectively; the other end of the first capacitor is connected to the drain of the first transistor, the drain of the third transistor and the gate of the fourth transistor; the other end of the second capacitor is connected to one end of the switch; the other end of the switch is connected to the drain of the second transistor, the gate of the third transistor and the drain of the fourth transistor; the source of the first transistor and the source of the second transistor are both connected to the power supply end; the source of the third transistor and the source of the fourth transistor are both connected to the ground; and the control end of the switch serves as the control signal input port.

3. The wireless modulation device for PWM control according to claim 2, characterized in that: The first capacitor and / or the second capacitor are on-chip capacitors; And / or, the switch is a MOS tube switch.

4. The wireless modulation device for PWM control according to claim 2, characterized in that: The first capacitor and / or the second capacitor are integrated with the switch on the same chip; And / or, the first capacitor and / or the second capacitor are integrated with one or more of the following transistors on the same chip: the first transistor, the second transistor, the third transistor, and the fourth transistor.

5. The wireless modulation device for PWM control according to claim 2, characterized in that: The frequency of the high-frequency signal is determined by the following parameters: the inductance value of a portion of the inductance in the secondary coil in the secondary signal transmission port, the first capacitor, the second capacitor, and the tube sizes of the first transistor to the fourth transistor; and the signal amplitude depends on the voltage value of the power supply end and the tube sizes of the first transistor to the fourth transistor.

6. The wireless modulation device for PWM control according to claim 5, characterized in that: The frequency of the high-frequency signal is approximately calculated as: Wherein, L is the inductance value of a part of the inductance in the secondary coil in the secondary signal transmission port, and C is the capacitance value of the first capacitor and the second capacitor.

7. The wireless modulation device for PWM control according to any one of claims 1 to 6, characterized in that: The wireless modulation device for PWM control is used to replace the isolation barrier in the isolated power supply system based on PWM control.

8. A wireless modulation method for PWM control, characterized in that: include: Inputting a PWM signal to a PWM control signal input port, wherein the PWM control signal input port is a PWM control signal input port provided in the wireless modulation device for PWM control as claimed in any one of claims 1 to 7; Power transmission of the power signal from the primary coil to the secondary coil is realized based on a power transformer, and the PWM signal is resonated to a preset high-frequency signal based on a resonant circuit and a part of the inductance taken from the secondary coil in the secondary signal transmission port, and the high-frequency signal is transmitted from the secondary coil to the primary coil to realize feedback signal transmission; wherein the power transformer and the resonant circuit are the power transformer and the resonant circuit provided in the wireless modulation for PWM control as described in any one of claims 1-7.

9. The wireless modulation method for PWM control according to claim 8, characterized in that: The frequency of the high-frequency signal obtained by resonance is approximately calculated in the following manner: determined according to the inductance value of a portion of the inductance in the secondary coil in the secondary signal transmission port and / or the capacitance values ​​of the first capacitor and the second capacitor in the resonant circuit, wherein the frequency of the high-frequency signal is: Wherein, L is the inductance value of a part of the inductance in the secondary coil in the secondary signal transmission port, and C is the capacitance value of the first capacitor and the second capacitor.

10. An isolated power supply system based on PWM control, comprising an inverter circuit, a rectifier circuit, an isolation barrier, a PWM encoding circuit and a PWM decoding circuit, characterized in that: The isolation barrier includes a power transformer provided by the wireless modulation device for PWM control as claimed in any one of claims 1 to 7; the PWM encoding circuit includes a feedback circuit and a resonant circuit, wherein the resonant circuit includes a resonant circuit provided by the wireless modulation device for PWM control as claimed in any one of claims 1 to 7; The primary power transmission port of the power transformer is electrically connected to the inverter circuit, the secondary power transmission port is electrically connected to the rectifier circuit, the primary signal transmission port is electrically connected to the PWM decoding circuit, the secondary signal transmission port is connected to the resonant circuit, and the PWM control signal input port of the resonant circuit is electrically connected to the feedback circuit; The feedback circuit is used to sample the output voltage of the rectifier circuit and generate a low-frequency PWM control signal of the corresponding frequency; the PWM decoding circuit is used to restore the high-frequency signal output from the primary signal transmission port into a low-frequency PWM signal; the inverter circuit is used to convert the input DC voltage into an AC power signal according to the PWM signal output by the PWM decoding circuit; the power transformer is used for power signal and high-frequency signal transmission; the rectifier circuit is used to convert the power signal from the power transformer into a DC output voltage.

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