Power supply circuit and electronic equipment

Abstract

The invention provides a power supply circuit and electronic equipment, which are applied to the technical field of switching power supplies, the circuit comprises a controller, a power conversion circuit and an under-voltage protection circuit, a SiC MOSFET switching tube is arranged in the power conversion circuit, the under-voltage protection circuit detects the current driving voltage output by a first driving port of the controller, and the current driving voltage is output by a second driving port of the controller. The current driving voltage of the SiC MOSFET switch tube is smaller than the preset protection voltage, the first control signal is output to the configuration port of the controller when the current driving voltage of the SiC MOSFET switch tube is smaller than the preset protection voltage, the controller is triggered to turn off the SiC MOSFET switch tube, and as the preset protection voltage is larger than or equal to the rated minimum driving voltage of the SiC MOSFET switch tube, reliable turn-off of the SiC MOSFET switch tube can be effectively controlled, and the reliability of the SiC MOSFET switch tube is improved. And the safety and the reliability of the SiC MOSFET switch tube and the power supply circuit are improved.

Description

Technical Field

[0001] The present application relates to the technical field of switching power supplies, and in particular to a power supply circuit and an electronic device. Background Art

[0002] The power switch tube is the core component of the power conversion circuit in the switching power supply. The power switch tube can control the power conversion circuit and the switching power supply as a whole to convert the DC power input to AC output and achieve precise control of the output voltage and current.

[0003] In practical applications, power switch tube SiC MOSFET has smaller on-resistance, smaller loss and better switching performance than Si MOSFET of the same specification. In recent years, it has been widely used as power switch tube of switching power supply. However, SiC MOSFET switch tube has relatively high requirements for driving voltage. When the switching power supply is turned off or short-circuited, it is difficult for the existing controller to control the reliable shutdown of SiC MOSFET switch tube, resulting in the risk of damage to SiC MOSFET switch tube and switching power supply. Summary of the invention

[0004] In view of this, the present application is committed to providing a power supply circuit and an electronic device, including an undervoltage protection circuit, which can detect the current driving voltage of the SiC MOSFET switch tube and turn off the switch tube when the current driving voltage is less than the preset protection voltage, so as to solve the problem of incomplete conduction or even damage of the SiC MOSFET switch tube.

[0005] In a first aspect, the present application provides a power supply circuit, including a controller and a power conversion circuit, wherein the controller includes any one of UCx842 and UCx844, wherein x=1, 2, 3; the power conversion circuit is provided with a SiCMOSFET switch tube for controlling the output of the power conversion circuit; the first drive port of the controller is electrically connected to the drive end of the SiCMOSFET switch tube;

[0006] The power supply circuit also includes an undervoltage protection circuit, wherein:

[0007] The undervoltage protection circuit is electrically connected to the configuration port of the controller;

[0008] The undervoltage protection circuit detects a current driving voltage output by the first driving port, and outputs a first control signal to the configuration port when the current driving voltage is less than a preset protection voltage, wherein the first control signal is used to trigger the controller to turn off the SiC MOSFET switch tube, wherein the preset protection voltage is greater than or equal to the rated minimum driving voltage of the SiC MOSFET switch tube.

[0009] In a possible implementation, the undervoltage protection circuit includes a reference circuit, a sampling circuit, and a protection circuit, wherein:

[0010] The reference circuit and the sampling circuit are electrically connected to the protection circuit respectively;

[0011] The sampling circuit samples the current driving voltage and outputs the sampled voltage to the protection circuit;

[0012] The reference circuit outputs a reference voltage to the protection circuit, and the reference voltage is related to the preset protection voltage;

[0013] The protection circuit outputs the first control signal when the sampled voltage is less than the reference voltage.

[0014] In a possible implementation manner, the input end of the reference circuit is electrically connected to the second driving port of the controller, and the output end of the reference circuit is electrically connected to the protection circuit;

[0015] The controller outputs a reference voltage through the second driving port, and the reference circuit converts the reference voltage into the reference voltage.

[0016] In a possible implementation, the reference circuit includes a voltage divider circuit, and the voltage divider circuit includes a first voltage divider resistor and a second voltage divider resistor, wherein:

[0017] One end of the first voltage-dividing resistor serves as an input end of the reference circuit, the other end of the first voltage-dividing resistor is electrically connected to one end of the second voltage-dividing resistor, and the other end of the second voltage-dividing resistor is grounded;

[0018] The voltage-dividing circuit divides the reference voltage and outputs the reference voltage from a connection point between the first voltage-dividing resistor and the second voltage-dividing resistor, wherein the reference voltage is greater than the reference voltage.

[0019] In a possible implementation, the reference circuit includes a voltage divider circuit and a reference power supply circuit, wherein:

[0020] The voltage divider circuit includes a first voltage divider resistor and a second voltage divider resistor, wherein:

[0021] One end of the first voltage-dividing resistor is electrically connected to the reference power supply circuit, and the other end of the first voltage-dividing resistor is electrically connected to one end of the second voltage-dividing resistor;

[0022] The other end of the second voltage-dividing resistor is grounded;

[0023] The reference power supply circuit outputs a reference voltage, and the reference voltage is greater than the reference voltage;

[0024] The voltage-dividing circuit divides the reference voltage and outputs the reference voltage from a connection point between the first voltage-dividing resistor and the second voltage-dividing resistor.

[0025] In a possible implementation, the sampling circuit includes a first sampling resistor and a second sampling resistor, wherein:

[0026] One end of the first sampling resistor is electrically connected to the power port of the controller, and the other end of the first sampling resistor is electrically connected to one end of the second sampling resistor;

[0027] The other end of the second sampling resistor is grounded;

[0028] The sampling voltage is output at a connection point between the first sampling resistor and the second sampling resistor.

[0029] In a possible implementation, the protection circuit includes a comparator, a pull-up resistor, and a controllable switch tube, wherein:

[0030] The inverting input terminal of the comparator is electrically connected to the sampling circuit, and the positive input terminal of the comparator is electrically connected to the reference circuit;

[0031] One end of the pull-up resistor is electrically connected to the power port of the comparator, and the other end of the pull-up resistor is electrically connected to the output end of the comparator;

[0032] The first end of the controllable switch tube is electrically connected to the configuration port, and the second end of the controllable switch tube is grounded;

[0033] The output end of the comparator is electrically connected to the control end of the controllable switch tube;

[0034] The comparator drives the controllable switch to conduct when the sampled voltage is less than the reference voltage, so as to output the first control signal to the configuration port.

[0035] In a possible implementation manner, the power supply port of the comparator is electrically connected to the second driving port of the controller;

[0036] After power-on, the controller outputs a reference voltage through the second driving port to drive the comparator to operate.

[0037] In a possible implementation manner, the undervoltage protection circuit is provided with a working power supply, and a control end of the working power supply is connected to a control port of the controller;

[0038] The controller outputs a second control signal through the control port after power-on startup, and the second control signal is used to control the working power supply to supply power to the undervoltage protection circuit.

[0039] In a second aspect, the present application provides an electronic device, comprising: a power supply circuit as described in any one of the first aspects of the present application, and at least one device module connected to the power supply circuit;

[0040] The power supply circuit supplies power to each of the device modules respectively.

[0041] Based on the above content, the power supply circuit provided in the present application includes a controller, a power conversion circuit and an undervoltage protection circuit, wherein the controller includes any one of UCx842 and UCx844 (x=1, 2, 3) and a SiC MOSFET switch tube is provided in the power conversion circuit, the first drive port of the controller is electrically connected to the drive end of the SiC MOSFET switch tube, the controller controls the on and off of the SiC MOSFET switch tube by outputting a drive voltage, and at the same time, the undervoltage protection circuit is electrically connected to the configuration port of the controller, based on the structure of the aforementioned circuit, the undervoltage protection circuit detects the current drive voltage output by the first drive port, and outputs a first control signal to the configuration port of the controller when the current drive voltage of the SiC MOSFET switch tube is less than a preset protection voltage, triggering the controller to turn off the SiC MOSFET switch tube, and since the preset protection voltage is greater than or equal to the rated minimum drive voltage of the SiC MOSFET switch tube, it can be ensured that the SiC can be turned off when the current drive voltage of the SiC MOSFET switch tube is less than the rated minimum drive voltage, or even before the rated minimum drive voltage is reached (so that there is a certain margin to ensure the correct shutdown of the SiC MOSFET switch tube). MOSFET switch tube, thereby effectively avoiding incomplete conduction of the SiC MOSFET switch tube and improving the safety and reliability of the SiC MOSFET switch tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 It is a circuit topology diagram of a switching power supply in the prior art;

[0044] Figure 2 is a topological schematic diagram of a power supply circuit provided by an embodiment of the present invention;

[0045] Figure 3 is a topological schematic diagram of another power supply circuit provided by an embodiment of the present invention;

[0046] Figure 4 It is a circuit topology diagram of a power supply circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0048] As mentioned earlier, the power switch tube is the core component of the power conversion circuit in the switching power supply. The power switch tube can be used to control the power conversion circuit and the switching power supply, convert the DC power input to the switching power supply into AC power output, and achieve precise control of the output voltage and current.

[0049] See also Figure 1 As shown, the switching power supply in the prior art is provided with a power conversion circuit and a controller IC1, wherein the power conversion circuit includes a power converter ( Figure 1 The flyback transformer is shown) and the switch tube Q1, as shown Figure 1 As shown, one end of the primary winding W1 of the flyback transformer serves as the input end of the switching power supply and is connected to the external power supply Ui, and the other end of the primary winding W1 is grounded via the switching tube Q1. Furthermore, the flyback transformer also includes a secondary winding W2 and an auxiliary winding Wf, wherein the secondary winding W2 is used to connect the power load Rs of the switching power supply, and the auxiliary winding Wf serves as the power supply of the controller IC1 and is electrically connected to the power port Vcc of the controller IC1. The auxiliary winding Wf provides the controller IC1 with a working voltage to meet the operation requirements of the controller IC1.

[0050] Furthermore, the first drive port Out of the controller IC1 is electrically connected to the drive end of the switch tube Q1, and the controller IC1 controls the on and off of the switch tube Q1 by outputting a drive signal (such as a PWM signal) to the switch tube Q1. Specifically, when the controller IC1 controls the switch tube Q1 to be turned on, due to the small internal resistance of the switch tube Q1, the power current of the external power supply Ui can flow through the primary winding W1 of the flyback transformer, the current of the primary winding W1 gradually increases, and the flyback transformer stores energy. When the controller IC1 controls the switch tube Q1 to be turned off, the internal resistance of the switch tube Q1 is large, the power current cannot flow, and the flyback transformer releases the electric energy stored in the early stage to supply power to the power load Rs. By controlling the duty cycle of the drive signal, the operation process of the power supply circuit can be regulated and controlled. It can be seen that the switch tube is the core part of the switching power supply and plays a vital role in the normal operation of the switching power supply.

[0051] It should be noted that Figure 1 The example shown is only a basic schematic diagram of the circuit topology of the switching power supply, which is mainly used to illustrate the basic working principle of the switching power supply. In practical applications, the switching power supply may also include other related components and circuits, which will not be elaborated in detail here. For specific implementation, please refer to the relevant technical implementation.

[0052] In practical applications, switch tubes can use IGBT, Si MOSFET (Si Metal-Oxide-Semiconductor Field-Effect Transistor), SiC MOSFET, etc. Among them, SiC MOSFET has smaller on-resistance, smaller loss and better switching performance than Si MOSFET of the same specification. Therefore, it has been widely used as a power switch tube for switching power supplies in recent years. However, SiC MOSFET has high requirements for driving voltage. Existing controllers, such as UC2844 controller, are difficult to control SiC MOSFET to shut down reliably when the switching power supply is shut down or short-circuited.

[0053] The inventor has found that the main reason for the above problem is that the UC2844 controller used in existing applications, before it is completely powered off (i.e. stops running), the driving voltage output by the first driving port is basically equal to the working voltage connected to the power port of the controller itself, which means that when the power supply voltage of the switching power supply drops, such as when the external power supply Ui loses power or the switching power supply is short-circuited, the working voltage connected to the controller drops synchronously, and the driving voltage output by the first driving port also drops until the controller stops running. However, the SiC MOSFET switch tube will be completely turned off only when the controller stops running, that is, in this process, the first driving port will output a driving voltage that is less than the rated minimum driving voltage of the SiC MOSFET switch tube within a certain period of time but will not completely turn off the SiC MOSFET switch tube, which causes the SiC MOSFET switch tube to be incompletely turned on, so that the SiC MOSFET switch tube is at risk of being damaged, affecting the safety and reliability of the power supply circuit.

[0054] In order to solve the above technical problems, the present invention provides a power supply circuit, including a controller and an undervoltage protection circuit, wherein the controller includes any one of UCx842 and UCx844, wherein x=1, 2, 3. The undervoltage protection circuit detects the current driving voltage output by the first driving port of the controller, and outputs a first control signal to the configuration port of the controller when the current driving voltage output by the controller is less than the preset protection voltage, triggering the controller to turn off the SiC MOSFET switch tube. Here, the preset protection voltage is greater than or equal to the rated minimum driving voltage of the SiC MOSFET switch tube, so that the SiC MOSFET switch tube can be completely turned off before the current driving voltage of the SiC MOSFET switch tube is less than the rated minimum driving voltage or even not less than the rated minimum driving voltage, thereby effectively avoiding the problem of incomplete conduction of the SiC MOSFET switch tube, reducing the probability of damage to the SiC MOSFET switch tube, and improving the safety and reliability of the power supply circuit operation.

[0055] The following is a detailed description of the structure of the power supply circuit in conjunction with the accompanying drawings. Figure 2 , Figure 2 As shown in the figure, the power supply circuit provided by this embodiment includes: a power supply main circuit 100 and an undervoltage protection circuit 200.

[0056] The power supply main circuit 100 includes a controller IC1 and a power conversion circuit 101. The power conversion circuit 101 is provided with a SiCMOSFET switch tube Q1 and a power converter, wherein, as mentioned above, the controller IC1 can be any one of UCx842 and UCx844 (x=1, 2, 3), and in practical applications, the power converter can select a flyback transformer or a forward transformer, and in this embodiment, the flyback transformer is used as an example for description.

[0057] Specifically, the flyback transformer includes a primary winding W1, at least one secondary winding W2 ( Figure 2 Only one secondary winding is shown in the figure) and the auxiliary winding Wf. One end of the primary winding W1 is used as the input end of the power supply main circuit 100, connected to the external power supply Ui, and the other end of the primary winding W1 is grounded through the SiC MOSFET switch tube Q1. Further, the secondary winding W2 is used to provide power to the power load Rs. Figure 2 As shown, in actual application, the output port of the secondary winding W2 is also connected to a rectifier diode Ds and a capacitor Cs. The auxiliary winding Wf serves as the power supply of the controller IC1, and is electrically connected to the power port Vcc of the controller IC1. The auxiliary winding Wf provides the controller IC1 with a working voltage to meet the operation requirements of the controller IC1. In the power supply circuit provided in this embodiment, the output port of the auxiliary winding Wf is connected to a rectifier diode D1 and a filter capacitor C3, wherein the rectifier diode D1 has the same function as the rectifier diode Ds, and is mainly used to realize rectification, and the filter capacitor C3 can filter out the AC component in the output of the auxiliary winding Wf, and provide a DC voltage for the controller IC1. Of course, in actual application, in order to provide a more stable working voltage to the controller IC1, other circuit components may be arranged between the auxiliary winding Wf and the controller IC1, which can be specifically realized by referring to the relevant technology, and will not be elaborated in detail here.

[0058] The first driving port Out of the controller IC1 is electrically connected to the driving end of the SiC MOSFET switch tube Q1 , and the controller IC1 controls the on and off of the SiC MOSFET switch tube Q1 by outputting a driving signal (such as a PWM signal) to the SiC MOSFET switch tube Q1 .

[0059] Further, combined with Figure 2As shown, the undervoltage protection circuit 200 is electrically connected to the configuration port Com of the controller IC1. Through the configuration port Com, the undervoltage protection circuit 200 can send a control signal to the controller IC1, so that the controller IC1 can directly turn off the SiC MOSFET switch tube. The undervoltage protection circuit 200 detects the current driving voltage output by the first driving port Out of the controller IC1 to the SiCMOSFET switch tube (the connection relationship is shown by a dotted line in the figure), and outputs a first control signal to the configuration port of the controller IC1 when the current driving voltage is less than the preset protection voltage. Of course, as mentioned above, in the case of using a PWM signal to control the SiC MOSFET switch tube Q1, the low level in the PWM signal controls the SiC MOSFET switch tube Q1 to turn off, and the high level in the PWM signal drives the SiC MOSFET switch tube Q1 to turn on. Therefore, the current driving voltage described in this embodiment and subsequent embodiments mainly refers to the high level output by the first driving port Out of the controller IC1 that can drive the SiC MOSFET switch tube Q1 to turn on.

[0060] The first control signal output by the undervoltage protection circuit 200 is used to trigger the controller IC1 to turn off the SiC MOSFET switch tube. In practical applications, the first control signal can be an interrupt signal of the controller IC1, or other types of signals that can prompt the controller IC1 to directly turn off the SiC MOSFET switch tube Q1. Under the premise of not exceeding the core idea of ​​the present invention, it also belongs to the scope of protection of the present invention. More importantly, in the power supply circuit provided in the embodiment of the present invention and subsequent embodiments, the preset protection voltage is set to be greater than or equal to the rated minimum drive voltage of the SiC MOSFET switch tube Q1. It should be noted here that the rated drive voltage of the SiC MOSFET switch tube Q1 is usually a range, for example, its rated drive voltage is between 14V-26V, that is, the rated minimum drive voltage is 14V, and the rated maximum drive voltage is 26V. Setting the preset protection voltage to be greater than or equal to its rated minimum driving voltage can leave a certain margin. Even in extreme cases, that is, when the preset protection voltage is equal to the rated minimum driving voltage of the SiC MOSFET switch tube Q1, it can ensure that the SiC MOSFET switch tube Q1 is reliably turned off when the current driving voltage is less than the rated minimum driving voltage, thereby avoiding incomplete conduction. When the preset protection voltage is set to be greater than the rated minimum driving voltage of the SiC MOSFET switch tube Q1, when the current driving voltage of the SiC MOSFET switch tube Q1 has not yet dropped to less than the rated minimum driving voltage, the SiC MOSFET switch tube Q1 is turned off, which can ensure that the switch tube is reliably turned off and avoid incomplete conduction.

[0061] In summary, the undervoltage protection circuit provided in this embodiment detects the current driving voltage output by the first driving port of the controller in the power supply circuit, and outputs a first control signal to the configuration port of the controller when the current driving voltage is less than the preset protection voltage, triggering the controller to turn off the SiC MOSFET switch tube. Since the preset protection voltage is set to be greater than or equal to the rated minimum driving voltage of the SiC MOSFET switch tube, it can be ensured that the SiC MOSFET switch tube is completely turned off when the current driving voltage of the SiC MOSFET switch tube is less than the rated minimum driving voltage, or even before it drops to the rated minimum driving voltage, thereby effectively avoiding the problem of incomplete conduction of the SiC MOSFET switch tube, reducing the probability of damage to the SiC MOSFET switch tube, and improving the safety and reliability of the power supply circuit.

[0062] For further information, see Figure 3 , Figure 3 is a topological diagram of another power supply circuit provided by an embodiment of the present invention, in Figure 2 On the basis of the illustrated embodiment, in the power supply circuit provided by this embodiment, the undervoltage protection circuit 200 specifically includes a sampling circuit 201 , a reference circuit 202 and a protection circuit 203 .

[0063] Combination Figure 3 As shown, the input end of the sampling circuit 201 collects the current driving voltage output by the first driving port of the controller IC1, and the output end of the sampling circuit 201 is electrically connected to the protection circuit 203, and outputs the obtained sampling voltage to the protection circuit 203. The reference circuit 202 is electrically connected to the protection circuit 203, and can output the reference voltage to the protection circuit 203. When the sampling voltage is less than the reference voltage, the protection circuit 203 outputs the aforementioned first control signal, so that the controller IC1 turns off the SiC MOSFET switch tube Q1.

[0064] It should be noted that, in order to correctly output the first control signal, the proportional relationship between the current driving voltage and the sampling voltage should be the same as the proportional relationship between the preset protection voltage and the reference voltage. For example, the current driving voltage is 15V, and the sampling voltage output by the sampling circuit 201 is 5V, that is, the corresponding proportional relationship between the two is 3:1. If the preset protection voltage is also set to 15V, in this case, in order to accurately characterize the magnitude relationship between the current driving voltage and the preset protection voltage, the reference voltage output by the reference circuit 202 should be 5V, that is, the proportional relationship between the preset protection voltage and the reference voltage is also 3:1. The above can be adjusted by resistors. Under the premise of determining the preset protection voltage, the reference voltage can be set based on the preset protection voltage. In this case, if the current driving voltage is further reduced, correspondingly, it will cause the sampling voltage to be less than the reference voltage, so the protection circuit 203 outputs the first control signal.

[0065] In a possible implementation, the reference circuit 202 includes a voltage divider circuit and a reference power supply circuit, wherein the voltage divider circuit includes a first voltage divider resistor and a second voltage divider resistor connected in series, specifically, one end of the first voltage divider resistor is electrically connected to the reference power supply circuit, and the other end is electrically connected to one end of the second voltage divider resistor, the other end of the second voltage divider resistor is grounded, and the connection point between the first voltage divider resistor and the second voltage divider resistor serves as an output end of the reference voltage and is electrically connected to the protection circuit 203. The reference power supply circuit outputs a reference voltage greater than the reference voltage, and after voltage division by the voltage divider circuit, provides the reference voltage to the protection circuit 203.

[0066] In another possible implementation, the controller IC1 includes a second drive port ( Figure 3 (not shown), after the controller IC1 is powered on, a reference voltage greater than the reference voltage can be output through the second drive port. In this case, the reference circuit 202 may only include a voltage divider circuit, specifically, the voltage divider circuit includes a first voltage divider resistor and a second voltage divider resistor, wherein one end of the first voltage divider resistor is used as the input end of the reference circuit, electrically connected to the second drive port of the controller IC1, the other end of the first voltage divider resistor is grounded via the other end of the second voltage divider resistor, and the connection point of the first voltage divider resistor and the second voltage divider resistor is electrically connected to the protection circuit as the output end of the reference circuit, and the voltage divider circuit divides the reference voltage output by the controller IC1 through the first voltage divider resistor and the second voltage divider resistor, thereby obtaining the reference voltage required for the protection circuit to perform voltage comparison.

[0067] Of course, the reference circuit may also include other specific implementations. Any circuit form that can provide the protection circuit with a reference voltage that satisfies the aforementioned proportional relationship is optional and also falls within the protection scope of the present invention without exceeding the core idea of ​​the present invention.

[0068] Furthermore, as mentioned above, in practical applications, the driving signal output by the controller IC1 is mostly a PWM signal, which itself consists of a high level and a low level that appear in a preset signal cycle. The high level is used to drive the SiC MOSFET switch tube to turn on, and the low level is used to control the SiC MOSFET switch tube to turn off. Therefore, for the sampling circuit 201, the difficulty in its implementation lies in how to accurately sample the current driving voltage, that is, the high level in the driving signal.

[0069] In a possible implementation, an enabling circuit is provided in the sampling circuit 201, and the enabling circuit is also controlled by the driving signal output by the first driving port of the controller IC1. When the first driving port outputs a high level, the sampling circuit 201 is enabled, the current driving voltage is collected, and the sampling voltage is output to the protection circuit 203. Correspondingly, when the first driving port outputs a low level, the sampling circuit 201 does not work and does not sample the current driving voltage. It can be understood that when the sampling circuit 201 does not work, the protection circuit 203 is configured to prohibit outputting the aforementioned first control signal.

[0070] It should be noted that the sampling circuit can also be implemented in other ways. Any circuit form that can accurately collect the current driving voltage output by the controller IC1 and feed it back to the protection circuit 203 is optional and also falls within the protection scope of the present invention without exceeding the core idea of ​​the present invention.

[0071] In this embodiment, the connection relationship between the undervoltage protection circuit 200 and the power supply main circuit 100, as well as the overall working process of the power supply circuit, can refer to the aforementioned Figure 2 The relevant contents of the corresponding embodiments will not be repeated here.

[0072] See also Figure 4 , Figure 4 FIG. 1 is a circuit topology diagram of a power supply circuit provided by an embodiment of the present invention. Figure 4 As shown, the sampling circuit 201 includes a first sampling resistor R1 and a second sampling resistor R2, wherein one end of the first sampling resistor R1 is electrically connected to the power port Vcc of the controller IC1, the other end of the first sampling resistor R1 is electrically connected to one end of the second sampling resistor R2, and the other end of the second sampling resistor R2 is grounded. At the same time, the connection point of the first sampling resistor R1 and the second sampling resistor R2 samples the working voltage of the power port Vcc and outputs the sampled voltage.

[0073] Due to the performance of the UCx842 and UCx844 series controllers themselves, during the process from the start-up of the controller to the complete power-off of the controller, the first drive port Out outputs a PWM signal, and the high level in the PWM signal, that is, the current drive voltage is substantially equal to the working voltage connected to the power port Vcc of the controller IC1. When the working voltage of the controller IC1 decreases, the high level output by the first drive port will also decrease accordingly. In other words, the working voltage connected to the power port of the controller IC1 can be used as the current drive voltage. Based on this, the sampling circuit 201 in this embodiment samples the working voltage of the controller IC1 and outputs the sampled voltage to the protection circuit 203.

[0074] It can be understood that there is a preset proportional relationship between the sampling voltage and the driving signal output by the first driving port, that is, the sampling voltage will change with the driving signal. If the sampling circuit is connected to the first driving port, when the first driving port outputs a low level (i.e., 0V) in the PWM signal, the sampling voltage must also be 0V. At this time, the sampling voltage is less than the reference voltage, which will cause the protection circuit 203 to erroneously output the first control signal. Based on this, this embodiment connects the input end of the sampling circuit to the power port of the controller IC1, making full use of the characteristic that the high level output by the first driving port of the controller IC1 is substantially equal to the working voltage Vcc connected to the power port, and the working voltage of the controller IC1 replaces the driving signal output by the first driving port, thereby effectively avoiding the protection circuit 203 from erroneously outputting the first control signal.

[0075] Furthermore, using the operating voltage of the controller IC1 as the high level in the drive signal it outputs can effectively simplify the circuit structure of the sampling circuit. The sampling voltage can be collected through a simple resistor divider circuit, eliminating the enabling circuit described in the aforementioned embodiment, which helps to reduce the overall design cost of the power supply circuit.

[0076] In this embodiment, the reference circuit 202 only includes a voltage-dividing circuit composed of a first voltage-dividing resistor R3 and a second voltage-dividing resistor R4, wherein one end of the first voltage-dividing resistor R3 serves as the input end of the reference circuit 202 and is electrically connected to the second drive port Vref of the controller IC1, the other end of the first voltage-dividing resistor R3 is grounded via the other end of the second voltage-dividing resistor R4, and the connection point between the first voltage-dividing resistor R3 and the second voltage-dividing resistor R4 serves as the output end of the reference circuit 202 and is electrically connected to the protection circuit 203. The voltage-dividing circuit divides the reference voltage output by the controller IC1 through the first voltage-dividing resistor R3 and the second voltage-dividing resistor R4 to obtain the reference voltage required for the protection circuit 203 to perform voltage comparison.

[0077] The reference voltage is provided by the controller IC1, which not only saves the cost of separately setting up a reference power supply circuit in the aforementioned embodiment, but also the working process of the reference circuit 202 can be controlled by the controller IC1, that is, only after the controller IC1 is powered on, will it output the reference voltage to the reference circuit 202, and then output the reference voltage.

[0078] In this embodiment, a charging capacitor C2 is further provided in the reference circuit 202 , and the charging capacitor C2 can slow down the change of the reference voltage output by the reference circuit 202 , thereby providing a more accurate reference voltage for the subsequent protection circuit 203 .

[0079] Furthermore, the embodiment of the present invention provides an optional configuration mode of the protection circuit. Specifically, the protection circuit 203 includes a comparator IC2, a pull-up resistor Ru and a controllable switch tube Q2, wherein:

[0080] The reverse input terminal of the comparator IC2 is electrically connected to the output terminal of the sampling circuit 201 to receive the sampling voltage, and the positive input terminal of the comparator IC2 is electrically connected to the output terminal of the reference circuit 202 to receive the reference voltage. One end of the pull-up resistor Ru is electrically connected to the power port of the comparator IC2, and the other end is electrically connected to the output terminal of the comparator IC2. Figure 2 As shown, in this embodiment, the power supply port of the comparator IC2 and the input end of the reference circuit 202 are connected to the second driving port of the controller IC1, and the reference circuit 202 converts the reference voltage output by the controller IC1 into the reference voltage, and the comparator IC2 operates under the drive of the reference voltage. It can be understood that the controller IC1 provides the comparator IC2 with the working voltage, which can realize the control of the comparator IC2 and the entire protection circuit by the controller IC1, which helps to further improve the reliability of the output of the first control signal.

[0081] In other implementations, the comparator IC2 may also be provided with an independent power supply circuit, and the independent power supply circuit provides an operating voltage for the comparator IC2. Of course, in the case where the reference circuit 202 is provided with a reference power supply circuit, the comparator IC2 may also share the reference power supply circuit with the reference circuit 202. Of course, the comparator IC2 may also be powered by other means, which also fall within the scope of protection of the present invention without exceeding the core concept of the present invention.

[0082] Further, combined with Figure 4 As shown, the first end of the controllable switch tube Q2 is electrically connected to the configuration port of the controller IC1, and the second end of the controllable switch tube Q2 is grounded. The output end of the comparator IC2 is electrically connected to the control end of the controllable switch tube Q2. In this embodiment, the protection circuit 203 is also provided with a charging capacitor C1, which can play a similar role as the aforementioned charging capacitor C2, and will not be expanded here.

[0083] Based on the above circuit structure, the comparator IC2 receives the sampling voltage output by the sampling circuit 201 and the reference voltage output by the reference circuit 202, and drives the controllable switch Q2 to conduct when the sampling voltage is less than the reference voltage, thereby outputting a first control signal to the configuration port Com of the controller IC1.

[0084] Based on the working principle of the comparator, it can be known that the critical condition for the output level of the output terminal of the comparator IC2 in this embodiment is that the voltage of the positive input terminal is equal to the voltage of the reverse input terminal. Combining the circuit structure of the voltage divider circuit 201 and the reference circuit 203, it can be known that, assuming that the preset protection voltage is Vp, the critical condition expression shown in the following formula (1) is obtained:

[0085]

[0086] Based on formula (1), the preset protection voltage is

[0087] It can be seen that the reference voltage V output by the controller IC1 ref Under the premise of determining the value, the desired preset protection voltage can be set by reasonably selecting the relevant resistors.

[0088] Combination Figure 4 As shown, the power-on start-up branch in the power supply main circuit provided in this embodiment includes a start-up resistor R5 and a start-up capacitor C3, wherein one end of the start-up resistor R5 is connected to one end of the primary winding W1 of the flyback converter, and the connection point between the two is connected to the external power supply Ui as the input end of the power supply main circuit, and the other end of the start-up resistor R5 is connected to one end of the start-up capacitor C3, and the other end of the start-up capacitor C3 is grounded. At the same time, the connection point between the start-up resistor R5 and the start-up capacitor C3 is connected to the power port Vcc of the controller IC1 and the branch where the auxiliary winding Wf is located. As for the working process of the power-on start-up branch, it will be expanded in the subsequent content and will not be described in detail here.

[0089] The following combines the above content and Figure 4 The circuit topology shown is used to introduce the working state of the power supply circuit provided in this embodiment. The working state of the power supply circuit can generally be divided into three stages: power-on startup stage, normal working stage and fault or shutdown stage, which are described below respectively.

[0090] The first stage: the power supply circuit is powered on and started up.

[0091] The external power supply Ui inputs a DC voltage, and the power supply circuit enters the power-on startup stage. First, the startup resistor R5 charges the startup capacitor C3, and the operating voltage of the power port Vcc of the controller IC1 gradually rises, but has not yet reached the start-up voltage of the controller IC1. At this time, the second drive port Vref of the controller IC1 outputs 0 volts, and the first drive port Out also outputs 0V, and the SiCMOSFET switch tube Q1 is in the off state.

[0092] exist Figure 4 In the circuit topology shown, the power port of the undervoltage protection circuit 200 is electrically connected to the second drive port of the controller IC1, that is, the reference voltage Vref output by the second drive port of the controller IC1 is used as the operating voltage of the comparator IC2 in the undervoltage protection circuit 200. Therefore, in the above process, the controller IC1 will not output the reference voltage Vref before completing the power-on startup. Therefore, the comparator IC2 in the protection circuit 203 will not operate, and it is even more impossible to drive the controllable switch tube Q2 to turn on, and the undervoltage protection circuit 200 will not work.

[0093] It should be noted that the first stage mentioned here mainly refers to the process in which the operating voltage of the power port Vcc of the controller IC1 gradually rises, but has not yet reached the stage in which the controller IC1 is powered on and starts to output the reference voltage. In this process, Figure 4 The circuit shown can ensure that the undervoltage protection circuit does not work in this stage, thereby ensuring the normal startup of the power supply circuit.

[0094] In another possible implementation, a working power supply may be provided in the undervoltage protection circuit 200, such as the reference power supply circuit provided for the reference circuit described in the above embodiment, and the working power supply provides the working voltage for the undervoltage protection circuit 200. In this case, the control end of the working power supply is connected to the control port ( Figure 4 The controller IC1 outputs a second control signal through the control port after power-on and startup, thereby controlling the working power supply to supply power to the undervoltage protection circuit 200, and the undervoltage protection circuit 200 starts to run. Of course, since the undervoltage protection circuit 200 will not obtain the second control signal before the controller IC1 completes power-on and startup, the present embodiment can also achieve the above purpose.

[0095] It is understandable that in the first stage, the operating voltage connected to the power port Vcc of the controller IC1 is very low, and the controller IC1 is in an undervoltage state. If the undervoltage protection circuit 200 is in the working state in this case, it will continue to output the first control signal, which will make it difficult for the power circuit as a whole to start normally. Through the above settings, while ensuring that the controller IC1 starts normally in the first stage, the normal startup of the power circuit can also be ensured.

[0096] The second stage: the normal working stage of the power supply circuit.

[0097] This stage mainly refers to the stage when the operating voltage of the controller IC1 rises to the stage where the controller IC1 can start normally. For example, when Vcc rises to 16 volts, the controller IC1 starts to work, the reference voltage output by the second drive port, and the undervoltage protection circuit 200 starts to work. Figure 4 It can be seen from the circuit topology shown that the sign of the undervoltage protection circuit starting to work is: the first driving port of the controller IC1 outputs a driving signal, and the second driving port outputs a reference voltage.

[0098] As mentioned above, the rated driving voltage of the SiC MOSFET switch tube Q1 is usually a range, and in this application, it is assumed that this range is 14-26V, that is, the rated minimum driving voltage of the SiC MOSFET switch tube Q1 is 14V. The preset protection voltage is set to 15V. Since the current driving voltage output by the first driving port of the controller IC1 is basically equal to the operating voltage of the controller IC1, that is to say, the current operating voltage of the controller IC1, 16V, is the current driving voltage output by the first driving port, which is greater than the rated minimum driving voltage of the SiC MOSFET switch tube Q1, 14V. Therefore, the controller IC1 can normally drive the SiC MOSFET switch tube Q1 to turn on, the flyback converter works normally, and the auxiliary winding Wf outputs the DC power rectified by the diode D1 to power the controller IC1. At the same time, through the voltage stabilizing diode D2, it is ensured that the operating voltage of the controller IC1 is within the allowable voltage range.

[0099] At this stage, the sampling circuit 201 outputs the sampling voltage (i.e. Figure 4 The voltage at point A shown in FIG. 1 is greater than the reference voltage output by the reference circuit 202 to the positive input terminal of the comparator IC2 (i.e. Figure 4 The voltage at point B shown in the figure), the comparator IC2 outputs a low level, the controllable switch tube Q2 is disconnected, and the undervoltage protection circuit 200 does not output the first control signal, that is, the undervoltage protection function is not triggered. In principle, at this time, the power supply circuit works normally and there is no undervoltage situation. The undervoltage protection circuit 200 should not trigger the output of the first control signal, thereby starting the undervoltage protection function.

[0100] It should be noted that, since the current driving voltage output by the controller IC1 is substantially equal to the working voltage connected to the power port of the controller IC1, the voltage at the connection point between the diode D1 and the filter capacitor C3 should be ensured to be greater than the starting voltage of the controller IC1 and less than the rated maximum driving voltage of 26V of the SiC MOSFET switch tube Q1 during design. This ensures that the controller IC1 can be started normally and the operation safety of the SiC MOSFET switch tube Q1 can be ensured.

[0101] Phase 3: A voltage drop occurs in the power circuit, such as a sudden short circuit or a power failure of the external power supply Ui (eg, normal shutdown).

[0102] When the voltage of Ui drops, for example, a short circuit or normal shutdown occurs, the voltage output by the auxiliary winding Wf in the power conversion circuit 101 will naturally drop. The sampling voltage output by the sampling circuit 201 to the reverse input terminal of the comparator IC2 will also drop. Since the operating voltage of the controller IC1 has not dropped to the shutdown voltage corresponding to the controller IC1 at this time, the controller IC1 and the comparator IC2 are still in normal working state, and the reference voltage of the second driving port remains unchanged, that is, the reference voltage output by the reference circuit 202 remains unchanged.

[0103] The sampling voltage continues to drop. When the sampling voltage is less than the reference voltage, the collector of the comparator IC2 is open-circuited and the pull-up resistor Ru charges the capacitor C1. When the voltage of C1 is greater than the turn-on voltage of the controllable switch tube Q2, the controllable switch tube Q2 is turned on, and the voltage of the configuration port Com of the controller IC1 is pulled down. The undervoltage protection circuit outputs the first control signal, so that the controller IC1 turns off the output of the first drive port, that is, turns off the SiC MOSFET switch tube Q1. In this way, when the external power input is powered off or there is a short circuit in the circuit, the SiC MOSFET switch tube Q1 can be properly turned off.

[0104] See also Figure 4 As shown, it is assumed that the operating voltage of the controller IC1 when it is shut down is 10V, that is, the controller IC1 will be powered off and shut down only when the operating voltage of the controller IC1 is less than 10V. Under this premise, if the undervoltage protection circuit provided by the present application is not provided in the power supply circuit, since the controller IC1 will be powered off and shut down only when the operating voltage of the controller IC1 is less than 10V, therefore, during the entire process in which the operating voltage of the controller IC1 gradually decreases from 16V to less than 10V, the controller IC1 is in a working state, and the driving voltage output by its first driving port will naturally gradually decrease from 16V to 10V. In this process, once the driving voltage is reduced to 14V, that is, lower than the rated minimum driving voltage of the SiC MOSFET switch tube Q1, the SiC MOSFET switch tube Q1 will not be fully turned on, and there is a risk of damage.

[0105] Through the undervoltage protection circuit provided by the present application, the operating voltage of the controller IC1 gradually decreases from the current operating voltage, such as 16V, so the voltage at point A (i.e., the sampling voltage output by the sampling circuit 201) also gradually decreases, and since the controller IC1 is still in a normal working state at this time, the voltage at point B (i.e., the reference voltage output by the reference circuit 202) remains unchanged. When the operating voltage of the controller IC1 is less than the preset protection voltage 15V (i.e., the current driving voltage output by the controller IC1 is less than 15V), the voltage at point A is less than the voltage at point B, the collector of the controller IC2 is open-circuited, the controllable switch tube Q2 is turned on, and the undervoltage protection circuit will output the first control signal, and the SiC MOSFET switch tube is turned off. At this time, the current driving voltage of the SiC MOSFET switch tube has not yet been reduced to the rated minimum voltage, that is, the undervoltage protection circuit realizes the reliable shutdown of the SiC MOSFET switch tube in this case, effectively avoiding the incomplete conduction of the SiC MOSFET switch tube.

[0106] Furthermore, if the operating voltage of the controller IC1 is greater than the preset protection voltage when the power supply circuit operates normally, for example, the operating voltage is 16V, then during the period when the operating voltage drops from 16V to 15V, the controller IC1 is still in operation and can still drive the SiC MOSFET switch tube Q1 normally. That is to say, in the power supply circuit provided by the present invention, the controller can still drive the SiC MOSFET switch tube Q1 normally during a period of time when the input power is off.

[0107] The present invention further provides an electronic device, comprising the power supply circuit provided by any of the aforementioned embodiments, and at least one device module connected to the power supply circuit, wherein the power supply circuit supplies power to each device module respectively.

[0108] Those skilled in the art will appreciate that the contents disclosed in this disclosure may be subject to various variations and improvements. For example, the various devices or components described above may be implemented by hardware, or by software, firmware, or a combination of some or all of the three.

[0109] In addition, although the present disclosure makes various references to certain units in the system according to embodiments of the present disclosure, any number of different units can be used and run on the client and / or server. The units are only illustrative, and different aspects of the system and method can use different units.

[0110] Flowcharts are used in this disclosure to illustrate the steps of the method according to the embodiments of the present disclosure. It should be understood that the preceding or following steps are not necessarily performed precisely in order. On the contrary, various steps may be processed in reverse order or simultaneously. At the same time, other operations may also be added to these processes.

[0111] Those skilled in the art will appreciate that all or part of the steps in the above method can be completed by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, such as a read-only memory, etc. Optionally, all or part of the steps in the above embodiment can also be implemented using one or more integrated circuits. Accordingly, each module / unit in the above embodiment can be implemented in the form of hardware or in the form of a software functional module. The present disclosure is not limited to any particular form of combination of hardware and software.

[0112] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. It should also be understood that terms such as those defined in common dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an idealized or highly formal sense, unless explicitly defined as such herein.

[0113] The above is an explanation of the present disclosure and should not be considered as a limitation thereof. Although several exemplary embodiments of the present disclosure are described, it will be readily understood by those skilled in the art that many modifications may be made to the exemplary embodiments without departing from the novel teachings and advantages of the present disclosure. Therefore, all such modifications are intended to be included within the scope of the present disclosure as defined in the claims. It should be understood that the above is an explanation of the present disclosure and should not be considered to be limited to the specific embodiments disclosed, and modifications to the disclosed embodiments and other embodiments are intended to be included within the scope of the appended claims. The present disclosure is defined by the claims and their equivalents.

Claims

1. A power supply circuit, comprising a controller and a power conversion circuit, wherein: The controller includes any one of UCx842 and UCx844, wherein x=1, 2, 3; the power conversion circuit is provided with a SiC MOSFET switch tube for controlling the output of the power conversion circuit; the first drive port of the controller is electrically connected to the drive end of the SiC MOSFET switch tube; It is characterized in that the power supply circuit also includes an undervoltage protection circuit, wherein: The undervoltage protection circuit is electrically connected to the configuration port of the controller; The undervoltage protection circuit detects a current driving voltage output by the first driving port, and outputs a first control signal to the configuration port when the current driving voltage is less than a preset protection voltage, wherein the first control signal is used to trigger the controller to turn off the SiC MOSFET switch tube, wherein the preset protection voltage is greater than or equal to the rated minimum driving voltage of the SiC MOSFET switch tube.

2. The power supply circuit according to claim 1, characterized in that: The undervoltage protection circuit includes a reference circuit, a sampling circuit and a protection circuit, wherein: The reference circuit and the sampling circuit are electrically connected to the protection circuit respectively; The sampling circuit samples the current driving voltage and outputs the sampled voltage to the protection circuit; The reference circuit outputs a reference voltage to the protection circuit, and the reference voltage is related to the preset protection voltage; The protection circuit outputs the first control signal when the sampled voltage is less than the reference voltage.

3. The power supply circuit according to claim 2, characterized in that: The input end of the reference circuit is electrically connected to the second driving port of the controller, and the output end of the reference circuit is electrically connected to the protection circuit; The controller outputs a reference voltage through the second driving port, and the reference circuit converts the reference voltage into the reference voltage.

4. The power supply circuit according to claim 3, characterized in that: The reference circuit includes a voltage divider circuit, and the voltage divider circuit includes a first voltage divider resistor and a second voltage divider resistor, wherein: One end of the first voltage-dividing resistor serves as an input end of the reference circuit, the other end of the first voltage-dividing resistor is electrically connected to one end of the second voltage-dividing resistor, and the other end of the second voltage-dividing resistor is grounded; The voltage-dividing circuit divides the reference voltage and outputs the reference voltage from a connection point between the first voltage-dividing resistor and the second voltage-dividing resistor, wherein the reference voltage is greater than the reference voltage.

5. The power supply circuit according to claim 2, characterized in that: The reference circuit includes a voltage divider circuit and a reference power supply circuit, wherein: The voltage divider circuit includes a first voltage divider resistor and a second voltage divider resistor, wherein: One end of the first voltage-dividing resistor is electrically connected to the reference power supply circuit, and the other end of the first voltage-dividing resistor is electrically connected to one end of the second voltage-dividing resistor; The other end of the second voltage-dividing resistor is grounded; The reference power supply circuit outputs a reference voltage, and the reference voltage is greater than the reference voltage; The voltage-dividing circuit divides the reference voltage and outputs the reference voltage from a connection point between the first voltage-dividing resistor and the second voltage-dividing resistor.

6. The power supply circuit according to claim 2, characterized in that: The sampling circuit includes a first sampling resistor and a second sampling resistor, wherein: One end of the first sampling resistor is electrically connected to the power port of the controller, and the other end of the first sampling resistor is electrically connected to one end of the second sampling resistor; The other end of the second sampling resistor is grounded; The sampling voltage is output at a connection point between the first sampling resistor and the second sampling resistor.

7. The power supply circuit according to claim 2, characterized in that: The protection circuit includes a comparator, a pull-up resistor and a controllable switch tube, wherein: The inverting input terminal of the comparator is electrically connected to the sampling circuit, and the positive input terminal of the comparator is electrically connected to the reference circuit; One end of the pull-up resistor is electrically connected to the power port of the comparator, and the other end of the pull-up resistor is electrically connected to the output end of the comparator; The first end of the controllable switch tube is electrically connected to the configuration port, and the second end of the controllable switch tube is grounded; The output end of the comparator is electrically connected to the control end of the controllable switch tube; The comparator drives the controllable switch to conduct when the sampled voltage is less than the reference voltage, so as to output the first control signal to the configuration port.

8. The power supply circuit according to claim 7, characterized in that: The power supply port of the comparator is electrically connected to the second driving port of the controller; After power-on, the controller outputs a reference voltage through the second driving port to drive the comparator to operate.

9. The power supply circuit according to claim 1, characterized in that: The undervoltage protection circuit is provided with a working power supply, and the control end of the working power supply is connected to the control port of the controller; The controller outputs a second control signal through the control port after power-on startup, and the second control signal is used to control the working power supply to supply power to the undervoltage protection circuit.

10. An electronic device, characterized in that: include: A power supply circuit according to any one of claims 1 to 9, and at least one device module connected to the power supply circuit; The power supply circuit supplies power to each of the device modules respectively.

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