An isolated power supply system and a wireless modulation device and method oriented to PWM control

Abstract

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

Description

Technical Field

[0001] This application relates to the fields of PWM signal modulation and isolated power supply technology, specifically to an isolated power supply system and a wireless modulation device and method for PWM control. Background Technology

[0002] In isolated power supply / wireless charging systems, power is transmitted through a transformer, and the control stage often uses PWM control to modulate the circuit load. PWM control regulates the output voltage V by turning the LC resonant oscillator on and off. ISO Since there is voltage isolation between the primary and secondary sides, the modulation signal often requires an additional feedback channel, such as a digital transformer or isolation capacitor. At the same time, lower frequency PWM signals (about 500kHz) cannot be directly transmitted to the transmitter 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 realize 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, this application provides an isolated power supply system and a wireless modulation device and method for PWM control, which can complete signal transmission based on power inductors, eliminating the need for additional isolation channels, simplifying the design and reducing costs.

[0005] This application provides the following technical solution:

[0006] This application provides a wireless modulation device for PWM control, comprising:

[0007] Power transformer: A transformer composed of a primary coil and a secondary coil, serving as an isolation medium for power and signal transmission. The primary coil includes a primary power transmission port and a primary signal transmission port, while the secondary coil includes a secondary power transmission port and a secondary signal transmission port. The primary signal transmission port is formed by taking a portion of the inductance from the primary coil and forming two external ports. The secondary signal transmission port is also formed by taking a portion of the inductance from the secondary coil and forming two external ports. Power signals are transmitted from the primary coil to the secondary coil through the primary power transmission port and the secondary power transmission port. PWM signals are transmitted from the secondary coil to the primary coil through the secondary signal transmission port and the primary signal transmission port.

[0008] The resonant circuit includes a PWM control signal input port, two resonant ports, and a resonant circuit. The two resonant ports are connected to the secondary signal transmission port. The PWM control signal input port is used to input the PWM signal to be modulated. The resonant circuit, together with a portion of the inductance taken from the secondary coil in the secondary signal transmission port, forms a new resonant unit to resonate a preset high-frequency signal under the control of the PWM signal, thereby realizing the wireless modulation and transmission of the PWM signal from the secondary coil side to the primary coil side. The connection between the two resonant ports of the resonant circuit 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 circuit and the secondary signal transmission port is connected; when the PWM signal is invalid, the connection between the two resonant ports of the resonant circuit and the secondary signal transmission port is disconnected.

[0009] Preferably, 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; 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 sources of the first transistor and the second transistor are both connected to a power supply terminal; the sources of the third transistor and the fourth transistor are both connected to ground; and the control terminal of the switch serves as the control signal input port.

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

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

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

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

[0014] Preferably, 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 taken from the secondary signal transmission port, the size of the first capacitor, the second capacitor, and the transistors of the first to fourth transistors; and the signal amplitude depends on the voltage value at the power supply terminal and the size of the transistors of the first to fourth transistors.

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

[0016]

[0017] Where L is the inductance value of a portion of the inductance taken from the secondary coil in the secondary 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 one of the present application is used to replace the isolation barrier in a PWM-controlled isolated power supply system.

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

[0020] The PWM signal is input to the PWM control signal input port, which is the PWM control signal input port provided in the wireless modulation device for PWM control as described in any one of the claims of this application;

[0021] The power transmission of the power signal from the primary coil to the secondary coil is achieved based on a power transformer, and the PWM signal is resonated to a preset high-frequency signal by a portion of the inductance taken from the secondary coil in the secondary signal transmission port based on a resonant circuit, and the high-frequency signal is transmitted from the secondary coil to the primary coil as a feedback signal; wherein, the power transformer and resonant circuit are the power transformer and resonant circuit provided in the wireless modulation for PWM control as described in any one of the claims of this application.

[0022] Preferably, the frequency of the high-frequency signal obtained by resonance is approximately calculated as follows: based on the inductance value of a portion of the inductance taken from 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:

[0023]

[0024] Where L is the inductance value of a portion of the inductance taken from the secondary coil in the secondary signal transmission port, and C is the capacitance value of the first capacitor and the second capacitor.

[0025] This application also provides an isolated power supply system based on PWM control, including an inverter circuit, a rectifier circuit, an isolation barrier, a PWM encoding circuit, and a PWM decoding circuit, wherein the isolation barrier includes a power transformer provided by a wireless modulation device for PWM control as described in any one of this application; the PWM encoding circuit includes a feedback circuit and a resonant circuit, wherein the resonant circuit includes a resonant circuit provided by a wireless modulation device for PWM control as described in any one of this 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 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.

[0027] 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 recover the low-frequency PWM signal from the high-frequency signal output from the primary side 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; and 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 at least one of the above-mentioned technical solutions adopted in this application can achieve include at least:

[0029] Compared to traditional digital signal transmission methods, this invention uses a power transformer and resonant circuit to construct PWM signal modulation and isolation transmission, which has the following advantages:

[0030] (1) Signal transmission is achieved through a power transformer, eliminating the need for additional digital isolation barriers and greatly reducing cost and area.

[0031] (2) The encoding circuit is simple and does not require bias circuits, oscillator circuits, etc. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

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

[0034] Figure 2 This is a schematic diagram of a PWM-controlled isolated power supply system for wireless transmission according to this application.

[0035] Figure 3 This is a waveform diagram of a key node in the wireless signal transmission in this application;

[0036] Figure 4 This is a schematic diagram of a capacitor and switch forming a resonant structure for wireless transmission in an isolated power supply system based on PWM control, as described in this application. Detailed Implementation

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

[0038] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will 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 set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0040] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

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

[0042] The functional block diagram of the isolated power supply system is attached. Figure 1As shown. The transmitting chip inverts 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 serve as the system's isolation barrier for power transmission and control signal feedback, respectively. The receiving chip rectifies the received AC power signal into a stable DC output voltage. In the signal transmission channel, a high-voltage isolation capacitor composed of SiO2 provides an insulation barrier between different voltage domains and provides a high-frequency signal transmission path. For isolated transmission of PWM signals, encoding and decoding circuits are needed to achieve isolated feedback transmission. A commonly used feedback digital channel scheme is the OOK on / off keying modulation scheme. Its principle is that the transmitter (TX) modulates the input signal onto the carrier frequency; that is, TX transmits a high-frequency signal through the isolation capacitor in one input state, while 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 is evident that the signal transmission of this scheme is highly dependent on additional isolation capacitors. In other words, in an isolated power supply system, an additional isolation channel is required for load modulation, which not only increases cost but also hinders chip miniaturization design.

[0043] In view of this, through in-depth research and improvement exploration of isolated power supply systems and their modulation methods, it was found that:

[0044] On the one hand, transformers can achieve isolated energy transfer between the primary and secondary sides, making power transformers a common component in isolated power supply systems. Therefore, if a power transformer can be used to transmit the feedback signal from the secondary side to the primary side, then the isolated transmission of the feedback signal should no longer require digital isolation capacitors.

[0045] Secondly, in an isolated power supply system based on PWM (Pulse Width Modulation) control, during the power transmission process, the secondary power inductance L... S Energy is always present. Therefore, if a small amount of power energy can be used to resonate and 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, then complex and expensive PWM encoding circuits can be eliminated.

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

[0047] On the one hand, the isolation chip (also called isolator, isolation circuit, isolation barrier, etc., without distinction) in the isolated power supply system is improved into an isolation barrier form containing only a power transformer 200 for power transmission, and the power transformer 200 is improved into the following new structural form, namely, the power transformer 200 includes: a primary-side power transmission port V PP V PN Inverter circuit 100 for connecting to the transmitter chip side; secondary power transmission port VSP V SN , for connecting the rectifier circuit 300 on the receiving chip side; and, the primary-side signal transmission port V PA V PB and secondary signal transmission port V SA V SB They are used to connect the decoding circuit 600 and the encoding circuit, respectively.

[0048] After the power transformer 200 is improved to a new isolation structure, since the power transformer 200 can realize the transmission of power energy from the primary side to the secondary side and the transmission of PWM feedback signal from the secondary side to the primary side, the digital isolation capacitor required for feedback signal transmission no longer needs to be set in the isolation chip, which simplifies the design of the isolation barrier and saves circuit area.

[0049] Secondly, to meet the needs 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. The resonant circuit 500 and the power transformer 200 form a new resonant unit. That is, in the PWM-controlled isolated power supply system, a portion of the inductance is taken from the secondary power inductor Ls and combined with the newly added resonant circuit 500 to form a new resonant frequency that can resonate higher than the PWM frequency, thereby realizing the transmission of the PWM feedback signal (i.e., the low-frequency PWM signal generated by the feedback circuit 400 according to the output voltage) from the secondary side to the primary side.

[0050] The low-frequency PWM signal used for power feedback modulation is used to turn the resonant circuit 500 on or off and is connected to the secondary signal transmission port V of the secondary power inductor Ls. SA V SB Therefore, when the resonant circuit 500 is connected, the resonant circuit 500 and a portion of the inductance taken from the secondary power inductor Ls form a new resonant unit, generating a high-frequency signal with a higher frequency than the PWM signal. Thus, the PWM feedback signal in the form of this high-frequency signal can reach the primary side from the secondary side through the isolation barrier, and be transmitted to the primary side signal transmission port V. PA V PB The decoding circuit 600 restores the feedback signal.

[0051] In summary, the improved technical solution does not require additional digital transformers / isolation capacitors, additional bias modules, oscillators, etc. It only requires forming corresponding signal transmission ports on the primary and secondary sides of the power transformer, and using a small portion of the inductance in the secondary inductor Ls to reconstruct a new resonant unit with the newly added resonant circuit. The principle and operation are 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 is based on the PWM signal in an isolated power supply system, other systems that are oriented towards PWM control and require isolated transmission of PWM signals can also be implemented using the device of this application. That is, the isolated power supply system is an application example of the wireless modulation scheme of the PWM signal in this application, and other similar application scenarios can refer to the application method of the PWM signal in the isolated power supply system.

[0053] The technical solutions provided by the various embodiments of this application are described below with reference to the accompanying drawings.

[0054] The core idea of ​​this invention is to use the power transformer in the isolated power supply system as the signal transmission path, without the need to add an additional digital isolation transformer / capacitor, 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 resonant circuit 500, and a decoding circuit 600. It should be noted that the inverter circuit 100 and the rectifier circuit 300 can be related circuits in the original scheme or newly designed circuits, and are not limited here.

[0056] The following is combined Figure 3 The schematic waveforms illustrate the composition and function of each circuit:

[0057] Inverter circuit 100: used to convert the input DC voltage V DD Inverted into a differential high-frequency oscillating power signal V PP and V PN And from V PP and V PN The port output is connected to the primary coil L of the miniature transformer 200. P ;

[0058] Power transformer 200: consisting of primary coil L P and secondary coil L S It consists of an isolation medium and enables 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: Used to convert the voltage at the secondary terminal V of transformer 200. SP and V SN The received high-frequency oscillation signal is rectified into a DC signal and provided to the output load;

[0060] Feedback circuit 400: Used to sample the output voltage and generate low-frequency PWM signals with different duty cycles to achieve a constant output voltage;

[0061] Resonant circuit 500: Used to convert low-frequency PWM signals into high-frequency oscillation signals from V SA V SB Export;

[0062] Decoding circuit 600: used to decode signals from V PA V PB The high-frequency oscillation signal is decoded and restored to a low-frequency PWM signal, which is then fed back to the inverter circuit 100.

[0063] The power transformer 200 includes: a primary-side power transmission port V PP V PN Used to connect to inverter circuit 100; secondary power transmission port V SP V SN Used to connect to rectifier circuit 300; primary-side signal transmission port V PA V PB Used to connect the decoding circuit 600; secondary signal transmission port V SA V SB It is used to connect the encoding circuit, wherein the encoding circuit can be a circuit composed of the aforementioned resonant circuit 500 and feedback circuit 400 to realize the modulation of the PWM signal (i.e., to realize encoding).

[0064] Among them, V PA V PB V is the port formed by taking a portion of the inductance from the primary coil. SP V SN The port is formed by taking a portion of the inductance from the secondary coil, and the two portions of inductance are coupled to each other to serve as an isolation channel for signal transmission.

[0065] Combination Figure 2 and Figure 3 The schematic diagram shows the overall circuit operation as follows: The power signal is transmitted through the primary-side power transmission port V. PP V PN and secondary power transmission port V SP V SN Power transfer is achieved; after the PWM signal resonates to a higher frequency signal, it is transmitted through the secondary signal transmission port V. SA V SB and primary side signal transmission port V PA V PB Signal transmission is achieved, and then the primary-side decoding circuit transmits the signal through V. PA V PB The PWM signal feedback transmission can be completed by decoding the high-frequency oscillation signal.

[0066] Additionally, due to V SA V SBThe inductance between the two sides is only a portion of the secondary inductance, and the resonant frequency needs to be distinguished from the power stage drive frequency and the chip ringing frequency. The capacitance of the on-chip resonant capacitor is very limited, therefore its oscillation amplitude is relatively small compared to the power inductor V. SP V SN The voltage between them is negligible, does not affect the power transmission of the power stage, and does not increase the output ripple.

[0067] from Figure 3 The waveform diagrams of key nodes in the signal transmission shown indicate that PWM_S is the low-frequency signal output by the secondary feedback control module. When PWM_S is high, the resonant circuit operates, and V... SP -V SN When a high-frequency signal is transmitted to the primary side, the output PWM_P of the decoding circuit is translated as high, and the primary power stage alternately works to transmit power; when PWM_S is low, the resonant circuit is turned off, the output PWM_P of the decoding circuit is translated as low, and the primary power stage is turned off.

[0068] In some examples, preferred embodiments of the resonant circuit 500 may be referred to Figure 4 The schematic circuit shown, i.e., the resonant circuit 500, can be simplified to the following circuit structure:

[0069] refer to Figure 4 As 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 and C2 and a switch S1. M P1 M P2 The source is connected to the power supply voltage VDD, M N1 M N2 The source is grounded to GND. Both the PMOS and NMOS transistors have their gates connected using cross-coupling, i.e., M... P1 M N1 The gate is connected to M P2 M N2 The drain end, M P2 M N2 The gate is connected to M P1 M N1 The drain end. M P2 M N2 The gate is connected to one end of the coupling capacitor C1, and the other end of C1 serves as the output V. SA M P1 M N1 The gate is connected to one end of switch S1, and the other end of S1 is connected to one end of coupling capacitor C2. The other end of C2 serves as the output V. SB .

[0070] Therefore, the PWM signal serves as the control signal for S1, connecting / disconnecting the resonant circuit via an on / off switch to achieve signal encoding. Its main principle is: when the PWM signal is high (i.e., the switch is closed), V... SA V SB The inductance between them will interact with the resonant capacitors C1 and C2 and the V of the MOSFET. GS To achieve resonance.

[0071] To ensure that the oscillation circuit does not affect the power transfer of the power stage, it is necessary to... SA V SB Coupler capacitors C1 and C2 are added across the inductors 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 V. SA V SB The inductance, resonant capacitances C1 and C2, and the size of the MOSFET are all factors. The signal amplitude depends on the value of VDD and the size of the MOSFET.

[0075] It is important to note that for isolated power supply systems using PWM control, when PWM is high, the power stage alternately charges and discharges the inductor at a fixed drive 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 no high-frequency oscillation signal is generated. At this time, the primary-side 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 barrier. The decoding circuit is high, the power stage restarts, and power is transmitted normally.

[0076] By properly setting the power supply voltage and MOSFET size of the resonant circuit, its oscillation amplitude is comparable to that of the power inductor V. SP V SN The voltage between them is negligible, does not affect the power transmission of the power stage, and does not increase the output ripple.

[0077] In summary, in a PWM-modulated isolated power supply system, a portion of the primary and secondary power inductors is used for modulation signal transmission. The high-frequency carrier signal generated by the secondary resonant circuit can pass through the isolation barrier without affecting power transmission. This solution eliminates the need for additional digital transformers / isolation capacitors, complex bias modules, oscillators, etc., greatly simplifying chip design.

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

[0079] In some preferred examples, the switch is preferably an electronic switch composed of transistors, such as a MOS transistor, and specifically a PMOS transistor or an NMOS transistor can be preferred depending on the circuit design.

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

[0081] In some preferred examples, the first capacitor and / or the second capacitor are integrated 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, the frequency of the high-frequency signal can be determined by the following parameters to meet the requirements of the resonant frequency setting: the inductance value of a portion of the inductance in the secondary coil taken from the secondary signal transmission port, the size of the first capacitor, the second capacitor, and the transistors of the first to fourth transistors; and the signal amplitude depends on the voltage value at the power supply terminal and the transistor sizes of the first to fourth transistors, flexibly adapting to the selection required for different resonant frequencies.

[0083] In this specification, the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the descriptions of the embodiments described later are relatively simple, and relevant parts can be referred to the descriptions of the foregoing embodiments.

[0084] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A wireless modulation device for PWM control, characterized in that, include: Power transformer: A transformer composed of a primary coil and a secondary coil, serving as an isolation medium for power and signal transmission. The primary coil includes a primary power transmission port and a primary signal transmission port, while the secondary coil includes a secondary power transmission port and a secondary signal transmission port. The primary signal transmission port is formed by taking a portion of the inductance from the primary coil and forming two external ports. The secondary signal transmission port is also formed by taking a portion of the inductance from the secondary coil and forming two external ports. Power signals are transmitted from the primary coil to the secondary coil through the primary power transmission port and the secondary power transmission port. PWM signals are transmitted from the secondary coil to the primary coil through the secondary signal transmission port and the primary signal transmission port. The resonant circuit includes a PWM control signal input port, two resonant ports, and a resonant circuit. The two resonant ports are connected to the secondary signal transmission port. The PWM control signal input port is used to input the PWM signal to be modulated. The resonant circuit includes a resonant capacitor. The resonant circuit, together with a portion of the inductance taken from the secondary coil in the secondary signal transmission port, forms a new resonant unit to resonate a preset high-frequency signal under PWM signal control, thereby realizing wireless modulation transmission of the PWM signal from the secondary coil side to the primary coil side. The connection between the two resonant ports of the resonant circuit 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 circuit and the secondary signal transmission port is connected; when the PWM signal is invalid, the connection between the two resonant ports of the resonant circuit and the secondary signal transmission port is disconnected. The PWM signal is a low-frequency PWM signal.

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 sources of the first transistor and the second transistor are both connected to the power supply terminal; the sources of the third transistor and the fourth transistor are both connected to ground; and the control terminal 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 transistor 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 on the same chip with one or more of the following transistors: 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 taken from the secondary signal transmission port, the size of the first capacitor, the second capacitor, and the transistors of the first to fourth transistors; and the signal amplitude depends on the voltage value at the power supply terminal and the size of the transistors of the first to fourth transistors.

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 follows: Where L is the inductance value of a portion of the inductance taken from 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 1-6, characterized in that, The wireless modulation device for PWM control is used to replace the isolation barrier in a PWM-controlled isolated power supply system.

8. A wireless modulation method for PWM control, characterized in that, include: The PWM signal is input to the PWM control signal input port, wherein the PWM control signal input port is the PWM control signal input port provided in the wireless modulation device for PWM control as described in any one of claims 1-7; The power transmission of the power signal from the primary coil to the secondary coil is realized based on the power transformer, and the PWM signal is resonated to a preset high-frequency signal based on the resonant circuit and a portion 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 as a feedback signal; wherein, the power transformer and the resonant circuit are the power transformer and 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 as follows: based on the inductance value of a portion of the inductance taken from 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: Where L is the inductance value of a portion of the inductance taken from 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 encoder circuit, and a PWM decoder circuit, characterized in that, The isolation barrier includes a power transformer provided by the wireless modulation device for PWM control as described in any one of claims 1-7; 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 described in any one of claims 1-7. Among them, 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 recover the low-frequency PWM signal from the high-frequency signal output from the primary side 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; and the rectifier circuit is used to convert the power signal from the power transformer into a DC output voltage.

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