Isolated power supply circuit and power device

Abstract

The application discloses an isolated power supply circuit and a power device, and belongs to the technical field of power supplies. The isolated power supply circuit comprises an inverter circuit, an input end of the inverter circuit is used for being connected with a direct current source, and the inverter circuit is configured to convert direct current output by the direct current source into alternating current; a first capacitor, a first end of the first capacitor is electrically connected with a first output end of the inverter circuit; a second capacitor, a first end of the second capacitor is electrically connected with a second output end of the inverter circuit; a rectifier circuit, an alternating current side of the rectifier circuit is electrically connected with a second end of the first capacitor and a second end of the second capacitor respectively, and a direct current side of the rectifier circuit is used for being connected with a load; and a voltage regulating circuit, the voltage regulating circuit is electrically connected on a loop between the inverter circuit and the rectifier circuit, and the voltage regulating circuit is configured to raise or lower an output voltage of the inverter circuit, so that the isolated power supply circuit realizes a step-up or step-down function, cost is reduced, and reliability and practicability are improved.

Description

Technical Field

[0001] This application belongs to the field of power supply technology, and in particular relates to an isolated power supply circuit and power equipment. Background Technology

[0002] Common DC-DC drive power supplies typically use transformers for primary-secondary isolation. Transformers require customized design and complex manufacturing processes, resulting in high production costs and bulky size. Furthermore, during operation, the presence of magnetic core leakage flux can generate electromagnetic interference, leading to low reliability.

[0003] Related technologies have proposed replacing traditional transformers with capacitors to achieve primary-secondary isolation. However, existing capacitor-isolated power supplies always have an output voltage equal to the input voltage, which has significant limitations. Utility Model Content

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes an isolated power supply circuit and power equipment, which uses a capacitor instead of a transformer to achieve electrical isolation, reducing costs and improving reliability. The voltage regulation circuit can realize the boost or buck function of the isolated power supply circuit, thereby improving the practicality of the isolated power supply circuit.

[0005] In a first aspect, this application provides an isolated power supply circuit, comprising:

[0006] Inverter circuit; the input terminal of the inverter circuit is used to connect to a DC source.

[0007] The first capacitor, the first terminal of the first capacitor is electrically connected to the first output terminal of the inverter circuit;

[0008] The first terminal of the second capacitor is electrically connected to the second output terminal of the inverter circuit.

[0009] The rectifier circuit has its AC side electrically connected to the second terminal of the first capacitor and the second terminal of the second capacitor, respectively, and its DC side is used to connect to the load.

[0010] The voltage regulation circuit is electrically connected in the loop between the inverter circuit and the rectifier circuit. The voltage regulation circuit is configured to increase or decrease the output voltage of the inverter circuit.

[0011] According to one embodiment of this application, the voltage regulation circuit includes:

[0012] The first inductor, the first end of the first inductor is electrically connected to the second end of the first capacitor and the first end of the AC side of the rectifier circuit respectively;

[0013] The third capacitor has its first terminal electrically connected to the second terminal of the first inductor, and its second terminal is electrically connected to the second terminal of the second capacitor and the second terminal of the AC side of the rectifier circuit.

[0014] According to one embodiment of this application, the voltage regulation circuit includes:

[0015] At least one resistive element is connected in the loop between the inverter circuit and the rectifier circuit.

[0016] According to one embodiment of this application, the resistor is a digital potentiometer.

[0017] According to one embodiment of this application, the voltage regulation circuit includes:

[0018] At least one second inductor is connected in the loop between the inverter circuit and the rectifier circuit.

[0019] According to one embodiment of this application, the voltage regulation circuit includes:

[0020] The third inductor has its first end electrically connected to the second end of the first capacitor, and its second end electrically connected to the first end of the AC side of the rectifier circuit.

[0021] The first switching transistor has its first terminal electrically connected to the second terminal of the third inductor and the first terminal of the AC side of the rectifier circuit, respectively, and its second terminal is electrically connected to the second terminal of the second capacitor.

[0022] According to one embodiment of this application, the rectifier circuit includes:

[0023] The unidirectional conducting device has its input terminal electrically connected to the second terminal of the third inductor and the first terminal of the first switching transistor, respectively, and its output terminal is used to be electrically connected to the load.

[0024] According to one embodiment of this application, the inverter circuit includes:

[0025] The second switching transistor has its first terminal electrically connected to the positive terminal of the DC source.

[0026] The third switch is electrically connected to the second terminal of the second switch and the first terminal of the first capacitor. The second terminal of the third switch is electrically connected to the negative terminal of the DC source and the first terminal of the second capacitor.

[0027] According to one embodiment of this application, the second switch is a P-type MOS transistor and the third switch is an N-type MOS transistor.

[0028] Secondly, this application provides an electrical device including at least one of the aforementioned isolated power supply circuits.

[0029] According to several embodiments of the isolated power supply circuit and power equipment of this application, the first capacitor and the second capacitor can realize electrical isolation between the DC source and the load. The production cost of the capacitor is lower than that of the transformer, which reduces the cost of the isolated power supply circuit. Moreover, the electromagnetic interference generated by the capacitor is also less than that of the transformer, which improves the reliability of the isolated power supply circuit. The voltage regulation circuit can increase or decrease the output voltage of the inverter circuit, thereby realizing the boost or buck function of the isolated power supply circuit and improving the practicality of the isolated power supply circuit.

[0030] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0031] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0032] Figure 1 This is a circuit diagram of an isolated power supply circuit in related technologies;

[0033] Figure 2 This is a structural block diagram of the isolated power supply circuit provided in the embodiments of this application;

[0034] Figure 3 This is one of the circuit diagrams of the isolated power supply circuit provided in the embodiments of this application;

[0035] Figure 4 This is a second circuit diagram of the isolated power supply circuit provided in the embodiments of this application;

[0036] Figure 5 This is the third circuit diagram of the isolated power supply circuit provided in the embodiments of this application;

[0037] Figure 6 This is the fourth circuit diagram of the isolated power supply circuit provided in the embodiments of this application;

[0038] Figure 7 This is a schematic diagram of the electrical stress of each component in the isolated power supply circuit provided in the embodiments of this application.

[0039] Figure label:

[0040] Inverter circuit 10, rectifier circuit 20, unidirectional conducting device 21, voltage regulation circuit 30, first capacitor C1, second capacitor C2, third capacitor C3, filter capacitor Co, load Ro, first diode D1, second diode D2, first switching transistor Q1, second switching transistor Q2, third switching transistor Q3, first inductor L1, second inductor L2, third inductor L3, resistive element R1. Detailed Implementation

[0041] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0042] In the following description, a "circuit" refers to a conductive loop consisting of at least one element or sub-circuit connected by an electrical or electromagnetic link. When an element or circuit is said to be "coupled to" or "connected to" another element, or when an element / circuit is said to be "coupled at" or "connected at" two nodes, it can be directly coupled to or connected to the other element, or there may be intermediate elements. The connection between elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there are no intermediate elements between them.

[0043] In the description, the terms "first," "second," etc., are used to distinguish similar objects, not to describe a specific order or sequence. It should be understood that such numerical descriptors can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class, not limited in number; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0044] Furthermore, the use of terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0045] In the field of power electronics, MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), hereinafter referred to as MOS transistor, has become one of the most widely used and frequently employed semiconductor power devices due to its high-frequency switching capability, low conduction loss, high reliability, and ease of driving. As a core component of modern power conversion, MOSFET plays a crucial role in power management, motor drives, new energy power generation, electric vehicles, and industrial frequency converters.

[0046] In existing MOSFET drive power supply technology, transformer-based isolated power supply circuits are typically used to meet their drive voltage requirements.

[0047] Figure 1 This is a circuit diagram of a traditional isolated power supply circuit. (Refer to...) Figure 1 Common isolated power supply circuits typically use transformers for primary and secondary isolation. Transformers require customized design and have complex manufacturing processes, resulting in high production costs and bulky size. Furthermore, during operation, the presence of magnetic core leakage flux can generate electromagnetic interference, leading to low reliability.

[0048] In related technologies, traditional transformers are replaced with capacitors to achieve primary-secondary isolation. However, existing capacitor-isolated power supply circuits have limited output voltage adjustment range, and the output voltage is always equal to the input voltage, which is quite restrictive.

[0049] Figure 2 This is a structural block diagram of the isolated power supply circuit provided in an embodiment of this application. (Refer to...) Figure 2 One embodiment of this application proposes an isolated power supply circuit, including: an inverter circuit 10, a first capacitor C1, a second capacitor C2, a rectifier circuit 20, and a voltage regulation circuit 30. The input terminal of the inverter circuit 10 is connected to a DC source; the first terminal of the first capacitor C1 is electrically connected to the first output terminal of the inverter circuit 10; the first terminal of the second capacitor C2 is electrically connected to the second output terminal of the inverter circuit 10; the AC side of the rectifier circuit 20 is electrically connected to the second terminals of the first capacitor C1 and the second capacitor C2, respectively, and the DC side of the rectifier circuit 20 is connected to a load Ro; the voltage regulation circuit 30 is electrically connected in the loop between the inverter circuit 10 and the rectifier circuit 20. The voltage regulation circuit 30 can utilize resistive elements to dissipate the output voltage of the inverter circuit 10, thereby reducing the output voltage of the inverter circuit 10, or it can utilize energy storage elements to store energy and transmit it to the subsequent circuit, thereby increasing the output voltage of the inverter circuit 10.

[0050] An isolated power supply circuit is a circuit that converts electrical energy from a DC source into DC current of different voltage or current levels.

[0051] The input terminal of the inverter circuit 10 is used to connect to a DC source. It is mainly used to invert the DC power output from the DC source, converting the DC power output from the DC source into an AC square wave signal of a specific frequency, so that the electrical energy output from the DC source can be transmitted to the subsequent circuit for processing through the first capacitor C1 and the second capacitor C2.

[0052] The specific structure of the inverter circuit 10 can be selected according to the actual application scenario, and is not limited here. For example, the inverter circuit 10 can be a full-bridge inverter circuit or a half-bridge inverter circuit, etc.

[0053] The first capacitor C1 is electrically connected between the output terminal of the inverter circuit 10 and the AC side of the rectifier circuit 20. The first capacitor C1 is also electrically connected between the second output terminal of the inverter circuit 10 and the AC side of the rectifier circuit 20, forming a symmetrical capacitive isolation channel to achieve electrical isolation and energy transfer between the DC source and the load Ro.

[0054] The specific types and capacitance values ​​of the first capacitor C1 and the second capacitor C2 can be selected according to the actual application scenario, and are not limited here. For example, the first capacitor C1 and the second capacitor C2 can both be high-voltage film capacitors or both be ceramic capacitors. The capacitance values ​​of the first capacitor C1 and the second capacitor C2 can be 1nF-100nF.

[0055] The AC side of the rectifier circuit 20 is electrically connected to the inverter circuit 10 through the first capacitor C1 and the second capacitor C2, while the DC side is connected to the downstream load Ro. It is mainly used to convert the AC energy coupled from the first capacitor C1 and the second capacitor C2 back into DC power for the load Ro. The specific structure of the rectifier circuit 20 can be selected according to the actual application scenario and is not limited here.

[0056] As an example, the rectifier circuit 20 includes a first diode D1 and a second diode D2. The anode of the first diode D1 is electrically connected to the second terminal of the first capacitor C1, and the cathode of the first diode D1 is electrically connected to the first terminal of the load Ro. The anode of the second diode D2 is electrically connected to the second terminal of the second capacitor C2 and the second terminal of the load Ro, respectively, and the cathode of the second diode D2 is electrically connected to the anode of the first diode D1.

[0057] The voltage regulation circuit 30 can be an impedance network composed of inductors, capacitors, resistors, or combinations thereof. The voltage regulation circuit 30 is connected in series or in parallel in the energy transmission loop between the inverter circuit 10 and the rectifier circuit 20. By changing the equivalent impedance on the loop between the inverter circuit 10 and the rectifier circuit 20, the voltage boosting or bucking function can be achieved.

[0058] The specific location of the voltage regulation circuit 30 can be selected according to the actual application scenario, and is not limited here. For example, the first side of the voltage regulation circuit 30 can be connected to the second terminal of the first capacitor C1 and the second terminal of the second capacitor C2, and the second side of the voltage regulation circuit 30 can be connected to the AC side of the rectifier circuit 20; or, the first side of the voltage regulation circuit 30 can be connected to the first output terminal and the second output terminal of the inverter circuit 10, and the second side of the voltage regulation circuit 30 can be connected to the second terminal of the first capacitor C1 and the second terminal of the second capacitor C2.

[0059] The specific structure of the voltage regulation circuit 30 can be selected according to the actual application scenario, and is not limited here. For example, the voltage regulation circuit 30 may include resistive elements connected in series in the loop between the inverter circuit 10 and the rectifier circuit 20, which can divide the voltage output by the inverter circuit 10, thereby realizing the step-down function of the isolated power supply circuit.

[0060] According to the isolated power supply circuit of this application, the first capacitor C1 and the second capacitor C2 can achieve electrical isolation between the DC source and the load Ro. The production cost of capacitors is lower than that of transformers, which reduces the cost of the isolated power supply circuit. Moreover, the electromagnetic interference generated by capacitors is also lower than that of transformers, which improves the reliability of the isolated power supply circuit. The voltage regulation circuit 30 can use resistive elements to consume the output voltage of the inverter circuit 10 to reduce the output voltage of the inverter circuit 10. Alternatively, it can use energy storage elements to store energy and then transmit it to the subsequent circuit to raise the output voltage of the inverter circuit 10. This realizes the boost or buck function of the isolated power supply circuit and improves the practicality of the isolated power supply circuit.

[0061] Figure 3 This is a circuit diagram of an isolated power supply circuit provided in an embodiment of this application. (Refer to...) Figure 3 In some embodiments, the voltage regulation circuit 30 includes a first inductor L1 and a third capacitor C3. The first terminal of the first inductor L1 is electrically connected to the second terminal of the first capacitor C1 and the first terminal of the AC side of the rectifier circuit 20, respectively; the first terminal of the third capacitor C3 is electrically connected to the second terminal of the first inductor L1, and the second terminal of the third capacitor C3 is electrically connected to the second terminal of the second capacitor C2 and the second terminal of the AC side of the rectifier circuit 20, respectively.

[0062] The first inductor L1 and the third capacitor C3 are connected in series between the second terminal of the first capacitor C1 and the second terminal of the second capacitor C2, forming an impedance adjustment network. The equivalent impedance of the first inductor L1 and the third capacitor C3 can be calculated using the following formula:

[0063]

[0064] Where Zo is the equivalent impedance of the impedance adjustment network, j is the imaginary unit, ω represents the angular velocity, r represents the line impedance (which is negligible), L is the inductance of the first inductor L1, and C is the capacitance of the third capacitor C3. By using different combinations of the first inductor L1 with different inductance values ​​and the third capacitor C3 with different capacitance values, different equivalent impedances Zo can be obtained.

[0065] At a fixed operating frequency, when it is necessary to boost the output voltage of the inverter circuit 10, at least one of the inductance value of the first inductor L1 and the capacitance value of the third capacitor C3 can be changed. For example, keeping the inductance value of the first inductor L1 unchanged, and selecting a third capacitor C3 with a larger capacitance value, the equivalent impedance Zo is reduced, thus boosting the output voltage to the target value. When it is necessary to de-boost the output voltage of the inverter circuit 10, at least one of the inductance value of the first inductor L1 and the capacitance value of the third capacitor C3 can also be changed. For example, keeping the inductance value of the first inductor L1 unchanged, and selecting a third capacitor C3 with a smaller capacitance value, the equivalent impedance Zo is increased, thus reducing the output voltage to the target value.

[0066] Figure 4 This is a circuit diagram of an isolated power supply circuit provided in an embodiment of this application. (Refer to...) Figure 4 In some embodiments, the voltage regulation circuit 30 includes at least one resistive element R1. The resistive element R1 is connected in the loop between the inverter circuit 10 and the rectifier circuit 20.

[0067] Resistive element R1 is used in electronic circuits to limit current or act as a load Ro. It follows Ohm's law, meaning the current flowing through resistive element R1 is directly proportional to the voltage across it. Therefore, it functions as a voltage divider in the circuit. In a step-down isolated power supply circuit, at least one resistive element R1 can be connected in series in the loop between the inverter circuit 10 and the rectifier circuit 20, or multiple resistive elements R1 can be connected in parallel in the loop between the inverter circuit 10 and the rectifier circuit 20. This allows for voltage division of the output voltage of the inverter circuit 10, achieving a step-down function. The connection position of resistive element R1 can be determined according to the actual application scenario and is not limited here.

[0068] It should be noted that the resistive element R1 can be a fixed resistor or a digital potentiometer. A digital potentiometer, like a sliding rheostat, can adjust the voltage in a circuit by changing its internal resistance value. In a voltage divider circuit, the digital potentiometer acts as an adjustable resistor, and since it can be controlled by a control signal without manual adjustment of its resistance value, it can precisely control the output voltage, thereby adjusting the voltage drop during the operation of an isolated power supply circuit.

[0069] As an example, the resistive element R1 can be a fixed resistor, with the first end of the resistive element R1 electrically connected to the first output terminal of the inverter circuit 10, and the second end of the resistive element R1 electrically connected to the first end of the first capacitor C1.

[0070] As another example, the first end of the resistive element R1 is electrically connected to the second output terminal of the inverter circuit 10, and the second end of the resistive element R1 is electrically connected to the first end of the second capacitor C2.

[0071] As another example, the first end of the resistive element R1 is electrically connected to the second end of the first capacitor C1, and the second end of the resistive element R1 is electrically connected to the first end of the AC side of the rectifier circuit 20.

[0072] As another example, the first end of the resistive element R1 is electrically connected to the second end of the second capacitor C2, and the second end of the resistive element R1 is electrically connected to the second end of the AC side of the rectifier circuit 20.

[0073] The number of resistive components R1 can be selected according to the actual application scenario, and there is no limitation here. For example, there can be 2, 3 or 4 resistive components R1, etc.

[0074] Figure 5 This is a circuit diagram of an isolated power supply circuit provided in an embodiment of this application. (Refer to...) Figure 5 In some embodiments, the voltage regulation circuit 30 includes at least one second inductor L2. The second inductor L2 is electrically connected in a loop between the inverter circuit 10 and the rectifier circuit 20.

[0075] In a step-down isolated power supply circuit, at least one second inductor L2 can be connected in series in the loop between the inverter circuit 10 and the rectifier circuit 20 to divide the voltage output by the inverter circuit 10 and achieve the step-down function. The connection position of the second inductor L2 can refer to the connection position of the resistor R mentioned above, and will not be repeated here.

[0076] The number of the second inductor L2 can also be selected according to the actual application scenario, and there is no limitation here. For example, in order to reduce the size of the inductor, two smaller inductors can be selected and connected in series in the loop between the inverter circuit 10 and the rectifier circuit 20 to achieve the voltage reduction requirement.

[0077] Figure 6 This is a circuit diagram of an isolated power supply circuit provided in an embodiment of this application. (Refer to...) Figure 6In some embodiments, the voltage regulation circuit 30 includes a third inductor L3 and a first switching transistor Q1. The first terminal of the third inductor L3 is electrically connected to the second terminal of the first capacitor C1, and the second terminal of the third inductor L3 is electrically connected to the first terminal of the AC side of the rectifier circuit 20; the first terminal of the first switching transistor Q1 is electrically connected to the second terminal of the third inductor L3 and the first terminal of the AC side of the rectifier circuit 20, respectively, and the second terminal of the first switching transistor Q1 is electrically connected to the second terminal of the second capacitor C2.

[0078] In the boost-type isolated power supply circuit, the third inductor L3 and the first switch Q1 are connected in series between the second terminals of the first capacitor C1 and the second terminals of the second capacitor C2. During the positive half-cycle of circuit operation, the first switch Q1 is turned on, and the electrical energy output by the inverter circuit 10 charges the first capacitor C1, the second capacitor C2, and the third inductor L3. During the negative half-cycle of circuit operation, the first switch Q1 is turned off, and the electrical energy stored in the third inductor L3 is superimposed with the electrical energy stored in the first capacitor C1 and the second capacitor C2 and then transmitted to the rectifier circuit 20. The voltage after rectification by the rectifier circuit 20 is greater than the output voltage of the DC source, thus realizing the boost function.

[0079] In some embodiments, the rectifier circuit 20 includes a unidirectional conducting device 21. The input terminal of the unidirectional conducting device 21 is electrically connected to the second terminal of the third inductor L3 and the first terminal of the first switching transistor Q1, respectively, and the output terminal of the unidirectional conducting device 21 is electrically connected to the load Ro.

[0080] It should be noted that a filter capacitor Co is usually provided on the DC side of the rectifier circuit 20. The first end of the filter capacitor Co is electrically connected to the output terminal of the unidirectional conducting device 21 and the first end of the load Ro, respectively, and the second end of the filter capacitor Co is electrically connected to the second end of the load Ro.

[0081] During the positive half-cycle of circuit operation, the first switch Q1 is turned on, and the inverter circuit 10 charges the first capacitor C1, the second capacitor C2, and the third inductor L3. The unidirectional conducting device 21 is reverse-biased and the filter capacitor Co provides power to the load Ro. During the negative half-cycle of circuit operation, the first switch Q1 is turned on, and the energy stored in the third inductor L3 is superimposed with the energy stored in the first capacitor C1 and the second capacitor C2, and then provides power to the load Ro through the unidirectional conducting device 21.

[0082] The specific type of the unidirectional conducting device 21 can be selected according to the actual application scenario, and is not limited here. For example, the unidirectional conducting device 21 can be a diode. The anode of the diode is electrically connected to the second terminal of the third inductor L3 and the first terminal of the first switching transistor Q1, respectively, and the cathode of the diode is electrically connected to the load Ro.

[0083] In some embodiments, the inverter circuit 10 includes a second switch Q2 and a third switch Q3. The first terminal of the second switch Q2 is electrically connected to the positive terminal of the DC source; the first terminal of the third switch Q3 is electrically connected to the second terminal of the second switch Q2 and the first terminal of the first capacitor C1, respectively; and the second terminal of the third switch Q3 is electrically connected to the negative terminal of the DC source and the first terminal of the second capacitor C2, respectively.

[0084] The second switch Q2 and the third switch Q3 are connected in series and then in parallel with the DC source, forming a push-pull circuit. Compared to a full-bridge circuit, the push-pull circuit only requires two switches to achieve the inverter function, reducing costs.

[0085] In some embodiments, the second switch Q2 is a P-type MOSFET and the third switch Q3 is an N-type MOSFET.

[0086] P-type and N-type MOSFETs have complementary conductivity characteristics. N-type MOSFETs conduct when a high-level voltage is applied to the gate and are cut off when a low-level voltage is applied; conversely, P-type MOSFETs conduct when a low-level voltage is applied to the gate and are cut off when a high-level voltage is applied. This complementary characteristic simplifies the design of the driver circuit. Typically, only an inverter or similar logic circuit is needed to generate complementary drive signals to control the conduction and cutoff of the P-type and N-type MOSFETs respectively. This simplifies the design of the driver circuit, reducing circuit complexity and cost. Furthermore, the complementarity of the drive signals also reduces switching losses and electromagnetic interference caused by drive signal mismatch.

[0087] It should be noted that the isolated power supply circuit of this application can be used as a driving circuit for a MOSFET, that is, the aforementioned load Ro is a MOSFET. The following will use... Figure 4 The working principle of the isolated power supply circuit of this application as a driving circuit for MOSFETs will be explained in general using the topology shown as an example.

[0088] The second switch Q2 and the third switch Q3 are turned on complementaryly with a 50% duty cycle each. When the second switch Q2 is turned on, the third switch Q3 is turned off. The electrical energy output from the DC source is converted into AC power by the inverter circuit 10 and charges the first capacitor C1 and the second capacitor C2. At the same time, the voltage is divided by the resistor R of the voltage regulation circuit 30 to obtain the required voltage, and then rectified to supply power to the MOSFET.

[0089] When the third switch Q3 is turned on, the second switch Q2 is turned off. The first capacitor C1 and the second capacitor C2 act as power sources. The output electrical energy is divided by the resistive element R of the voltage regulation circuit 30 to obtain the required voltage, and then rectified to supply power to the MOSFET.

[0090] MOSFETs require relatively low drive power, typically less than 1W, and have a relatively high operating frequency, typically above 250kHz. Therefore, the energy required from the capacitor in each cycle is relatively small. Thus, only a small capacitor, C1, and a small capacitor, C2, are needed to drive the MOSFET, ensuring that the current and voltage stresses on the capacitors are within a small range.

[0091] Figure 7 This is a schematic diagram showing the electrical stress of each component in an isolated power supply circuit that converts a 24V DC source to a 20V source, as provided in an embodiment of this application. (Refer to...) Figure 7 The inverter circuit 10 has an output power of 2W, and the second switch Q2 and the third switch Q3 operate at a frequency of 250kHz. The first row shows the current stress of the first capacitor C1 and the second capacitor C2; the second row shows the voltage stress of the first capacitor C1 and the second capacitor C2; the third row shows the output voltage Vo; and the fourth row shows the current stress of the second diode D2 and the third diode in the rectifier circuit 20. Figure 7 It can be seen that the voltage and current stresses of the first capacitor C1 and the second capacitor C2, as well as the current stresses of the second diode D2 and the third diode, are all within a small range, which improves the reliability of the isolated power supply circuit.

[0092] One embodiment of this application provides an electrical device including at least one of the aforementioned isolated power supply circuits.

[0093] The specific structure and working principle of the isolated power supply circuit can be referred to the aforementioned embodiments, and will not be repeated here.

[0094] According to the power equipment of this application, the first capacitor C1 and the second capacitor C2 in the isolated power supply circuit can achieve electrical isolation between the DC source and the load Ro. The production cost of the capacitor is lower than that of the transformer, which reduces the cost of the isolated power supply circuit. Moreover, the electromagnetic interference generated by the capacitor is also less than that of the transformer, which improves the reliability of the isolated power supply circuit. The voltage regulation circuit 30 can increase or decrease the output voltage of the inverter circuit 10, thereby realizing the boost or buck function of the isolated power supply circuit and improving the practicality of the isolated power supply circuit.

[0095] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. An isolated power supply circuit, characterized in that, include: An inverter circuit, wherein the input terminal of the inverter circuit is connected to a DC source; A first capacitor, the first terminal of which is electrically connected to the first output terminal of the inverter circuit; The second capacitor has its first terminal electrically connected to the second output terminal of the inverter circuit. A rectifier circuit, wherein the AC side of the rectifier circuit is electrically connected to the second terminal of the first capacitor and the second terminal of the second capacitor, respectively, and the DC side of the rectifier circuit is connected to the load. A voltage regulation circuit is electrically connected in the loop between the inverter circuit and the rectifier circuit, and the voltage regulation circuit is configured to increase or decrease the output voltage of the inverter circuit.

2. The isolated power supply circuit according to claim 1, characterized in that, The voltage regulation circuit includes: The first inductor has its first end electrically connected to the second end of the first capacitor and the first end of the AC side of the rectifier circuit, respectively. The third capacitor has its first terminal electrically connected to the second terminal of the first inductor, and its second terminal electrically connected to the second terminal of the second capacitor and the second terminal of the AC side of the rectifier circuit.

3. The isolated power supply circuit according to claim 1, characterized in that, The voltage regulation circuit includes: At least one resistive element is connected in the loop between the inverter circuit and the rectifier circuit.

4. The isolated power supply circuit according to claim 3, characterized in that, The resistive element is a digital potentiometer.

5. The isolated power supply circuit according to claim 1, characterized in that, The voltage regulation circuit includes: At least one second inductor is connected in a loop between the inverter circuit and the rectifier circuit.

6. The isolated power supply circuit according to claim 1, characterized in that, The voltage regulation circuit includes: The third inductor has its first end electrically connected to the second end of the first capacitor, and its second end electrically connected to the first end of the AC side of the rectifier circuit. The first switching transistor has its first terminal electrically connected to the second terminal of the third inductor and the first terminal of the AC side of the rectifier circuit, respectively, and its second terminal is electrically connected to the second terminal of the second capacitor.

7. The isolated power supply circuit according to claim 6, characterized in that, The rectifier circuit includes: A unidirectional conducting device, wherein the input terminal of the unidirectional conducting device is electrically connected to the second terminal of the third inductor and the first terminal of the first switching transistor, and the output terminal of the unidirectional conducting device is used to be electrically connected to the load.

8. The isolated power supply circuit according to any one of claims 1-7, characterized in that, The inverter circuit includes: The second switching transistor has its first terminal electrically connected to the positive terminal of the DC source. The third switch; the first terminal of the third switch is electrically connected to the second terminal of the second switch and the first terminal of the first capacitor, respectively, and the second terminal of the third switch is electrically connected to the negative terminal of the DC source and the first terminal of the second capacitor, respectively.

9. The isolated power supply circuit according to claim 8, characterized in that, The second switch is a P-type MOS transistor, and the third switch is an N-type MOS transistor.

10. An electrical device, characterized in that, It includes at least one isolated power supply circuit according to any one of claims 1-9.

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