A heating power supply circuit

Abstract

The application discloses a heating power supply circuit, comprising a load power supply loop for connecting a load and a power supply, and two first switch units connected in series in the loop, wherein the first switch unit comprises a controlled conduction switch and a unidirectional conduction switch, the controlled conduction switch comprises a first end, a second end and a control end, and is used for realizing conduction / cutoff based on a control signal received by the control end; the first ends of the two first switch units are connected in common; the unidirectional conduction switch is connected in parallel with the controlled conduction switch and is used for conducting when a preset pressure difference exists between the first end and the second end; and the conduction loss of the controlled conduction switch is smaller than that of the unidirectional conduction switch. When the circuit is accidentally connected reversely with the positive and negative poles of an external power supply, one of the unidirectional conduction switches functions as a transient reverse prevention device. Moreover, the conduction loss of the controlled conduction switch is smaller than that of the unidirectional one, thereby effectively solving the loss caused by the fixed forward voltage drop of the diode in the original solution.

Description

Technical Field

[0001] This application relates to the field of new energy battery technology, and in particular to a heating power supply circuit. Background Technology

[0002] Low-voltage battery management systems (BMS) are commonly equipped with heating power supply circuits for use in cold environments, low-temperature charging protection, and emergency heating scenarios. These circuits provide controlled power to heating films, heating resistors, or other components. Such systems typically require high efficiency, scalable output capability, and good thermal safety within a limited volume.

[0003] Existing low-voltage battery management systems (BMS) heating power supply circuits mostly use diodes as rectification, freewheeling, or reverse connection protection components. This type of solution is simple in structure, low in cost, and easy to implement, but it reveals a significant bottleneck when improving output capacity: when the output current is large, the forward voltage drop of the diode will cause significant losses, which are directly converted into heat, leading to increased device temperature and a significant reduction in system efficiency. Utility Model Content

[0004] In view of the shortcomings of the existing technology, this application provides a heating power supply circuit that can reduce losses and improve output capability.

[0005] The technical solution of this application is implemented as follows: This application provides a heating power supply circuit, including a load power supply circuit for connecting a load and a power source, and two first switching units connected in series in the circuit. Each first switching unit includes a controlled conducting switch and a unidirectional conducting switch. The controlled conducting switch includes a first terminal, a second terminal, and a control terminal. The controlled conducting switch is used to turn on / off based on a control signal received from the control terminal. The first terminals of the two first switching units are connected together. The unidirectional conducting switch is connected in parallel with the controlled conducting switch and is used to turn on when there is a preset voltage difference between the first terminal and the second terminal. The conduction loss of the controlled conducting switch is less than that of the unidirectional conducting switch.

[0006] Through the aforementioned technical means, this application connects the first terminals of two first switching units together. Therefore, as long as the signals at the control terminals are consistent, the two controlled on / off switches can achieve synchronous on / off. When the circuit is accidentally connected to the opposite polarity of the external power supply, the controlled on / off switches of both first switching units are in the off state. Since the two unidirectional on / off switches of the two first switching units are opposite, one of the unidirectional on / off switches provides instantaneous reverse protection. Thus, this application can provide reverse connection protection by adding a first switching unit. At the same time, the newly added first switching unit has lower conduction losses due to the controlled on / off switches, meaning the controlled on / off switches are low-loss on / off, effectively solving the loss caused by the fixed forward voltage drop of the diode in the original solution. This improves the output capability and thermal stability of the circuit without significantly increasing size and cost.

[0007] In one implementation, the unidirectional conduction switch is a diode, and the controlled conduction switch is an active switch.

[0008] Through the above technical means, the active switch provides a low-resistance main path during normal operation, which significantly reduces conduction voltage drop loss, improves efficiency, and reduces thermal design pressure; the diode, as a simple and reliable passive unidirectional channel, quickly blocks the reverse current path when the power supply is reversed, improving the system's fault tolerance and reliability.

[0009] In one embodiment, the first switching unit includes a MOSFET, with the first terminal, the second terminal, and the control terminal being the source, drain, and gate of the MOSFET, respectively; the unidirectional conduction switch is the body diode of the MOSFET, and the controlled conduction switch is the source-drain conduction channel of the MOSFET.

[0010] Through the above-mentioned technical means, this application uses a MOSFET to simultaneously realize the functions of unidirectional conduction switch and controlled conduction switch. The body diode of the MOSFET acts as a passive unidirectional channel, and the source-drain channel of the MOSFET acts as a low-resistance main path, reducing the number of independent diodes and other devices and improving the integration.

[0011] In one implementation, the first switching unit is a PMOS transistor.

[0012] Using the above techniques, driving a PMOS transistor is simpler; it only requires pulling the gate low to turn it on, without needing to provide a gate voltage higher than the power supply. This makes the control circuit simpler and the cost lower.

[0013] In one embodiment, the heating power supply circuit includes a first bias resistor and / or a Zener diode. The first bias resistor is connected between the source and gate of the PMOS transistor, the anode of the Zener diode is connected to the gate of the PMOS transistor, and the cathode of the Zener diode is connected to the source of the PMOS transistor.

[0014] Through the aforementioned technical means, the first bias resistor is connected between the PMOS source (S) and gate (G) to provide a voltage difference between the gate and source, preventing false turn-on upon power-up. The Zener diode limits the voltage of the PMOS transistor to its rated value, preventing damage to the device due to overload caused by high input voltage or sudden load changes.

[0015] In one implementation, the control terminals of the controlled on switches of the two first switching units are connected to the same signal.

[0016] By using the above-mentioned technical means, the control terminals of the controlled conducting switches of the two first switching units are connected to the same signal, so as to realize the synchronous switching of the two first switching units, simplify the control, and uniformly shut down in abnormal situations, thereby improving safety.

[0017] In one embodiment, the heating power supply circuit further includes a second switching unit. One end of the second switching unit is connected to the negative terminal of the power supply, and the other end of the second switching unit is connected to the control terminal. The controlled terminal of the second switching unit is used to connect to the controller to receive control signals. Under the control of the control signals, the control terminal of the first switching unit is connected or disconnected from the negative terminal of the power supply by turning on / off, thereby controlling the voltage difference between the control terminal of the first switching unit and the first terminal of the first switching unit to realize the controlled switching on / off.

[0018] Through the above-mentioned technical means, the second switching unit is used to uniformly release the control terminal potential of the controlled conducting switch by the control signal output by the controller. In this way, by connecting / disconnecting the control terminal and the negative terminal of the power supply, the voltage difference between the control terminal and the first terminal is modulated, thereby realizing the on / off control of the controlled conducting switch, achieving low-loss control of connecting / disconnecting the control terminal and the negative terminal of the power supply, clarifying the voltage difference between the control terminal and the first terminal, and thus stably and controllably driving the controlled conducting switch.

[0019] In one implementation, the second switching unit is an NMOS transistor.

[0020] Through the above technical means, the NMOS transistor has strong low-side pull-down capability and low loss, and can quickly and stably establish / release the control terminal voltage difference, thereby improving the turn-on and turn-off speed.

[0021] In one embodiment, the heating power supply circuit includes a current-limiting resistor and / or a filter unit. The gate of the NMOS transistor is connected to the controller via the current-limiting resistor, and the filter unit is connected between the gate and source of the NMOS transistor.

[0022] Through the above technical means, the current-limiting resistor limits the instantaneous charging and discharging current of the NMOS transistor gate by the controller, significantly suppressing ringing and false triggering; the filtering unit plays a filtering role, improving the stability and anti-interference of the gate drive.

[0023] In one embodiment, the heating power supply circuit includes a first output terminal for connecting to the positive terminal of the load and a second output terminal for connecting to the negative terminal of the load. The heating power supply circuit includes a voltage detection unit connected between the first and second output terminals for detecting the output voltage between the first and second output terminals and outputting it to the controller, so that the controller outputs a control signal to the control terminal based on the output voltage to turn the controlled on / off switch on / off. And / or, a current detection unit is connected in series in the load power supply circuit for detecting the power supply current in the load power supply circuit and outputting it to the controller, so that the controller outputs a control signal to the control terminal based on the power supply current to turn the controlled on / off switch on / off.

[0024] By using the above-mentioned technical means, a voltage detection unit is set between the first output terminal and the second output terminal, or a current detection unit is connected in series in the load power supply circuit, and the detection results are fed back to the controller, thereby realizing real-time control of the output voltage and power supply current, realizing constant voltage / constant current / current limiting and other working modes, and improving the stability and accuracy of heating power.

[0025] In one embodiment, the heating power supply circuit includes an overcurrent protection device connected in series in the power supply circuit to disconnect when the current in the power supply circuit exceeds a preset threshold.

[0026] By using the above-mentioned technical means, an overcurrent protection device is connected in series in the power supply circuit to automatically disconnect the circuit when the current in the power supply circuit exceeds a preset threshold, thereby realizing hardware-level overcurrent / short-circuit protection and preventing damage to the controlled switching, load and power supply.

[0027] The beneficial effects of this application are as follows: This application provides a heating power supply circuit, including a load power supply circuit for connecting a load and a power source, and two first switching units connected in series in the circuit. The first switching unit includes a controlled conducting switch and a unidirectional conducting switch. The controlled conducting switch includes a first terminal, a second terminal, and a control terminal. The controlled conducting switch is used to turn on / off based on the control signal received by the control terminal. The first terminals of the two first switching units are connected together. The unidirectional conducting switch is connected in parallel with the controlled conducting switch and is used to turn on when there is a preset voltage difference between the first terminal and the second terminal. The conduction loss of the controlled conducting switch is less than that of the unidirectional conducting switch. Compared to existing technologies, this application uses a common connection at the first terminals of two first switching units. Therefore, as long as the signals at the control terminals are consistent, the two controlled on / off switches can achieve synchronous on / off. When the circuit is accidentally connected to the opposite polarity of an external power supply, both controlled on / off switches of the two first switching units are in the off state. Since the two unidirectional on / off switches of the two first switching units are opposite, one of the unidirectional on / off switches provides instantaneous reverse protection. Thus, this application can provide reverse connection protection by adding a new first switching unit. Simultaneously, the newly added first switching unit has lower conduction losses due to the controlled on / off switches, meaning the controlled on / off switches are low-loss on / off, effectively solving the loss caused by the fixed forward voltage drop of the diode in the original solution. This improves the output capability and thermal stability of the circuit without significantly increasing size and cost. Attached Figure Description

[0028] Figure 1 One of the circuit diagrams of a heating power supply circuit according to this application is shown; Figure 2 A second circuit diagram of a heating power supply circuit according to this application is shown; Figure 3 The third circuit diagram of a heating power supply circuit according to this application is shown; Figure 4 The fourth circuit diagram of a heating power supply circuit according to this application is shown; Figure 5 The fifth circuit diagram of a heating power supply circuit according to this application is shown; Reference numerals: Q1, first switching unit; Q2, second switching unit; R1, first bias resistor; R3, voltage divider resistor; R5, second bias resistor; R7, current limiting resistor; D, Zener diode; C, filter unit; 100, load; 200, power supply circuit. Detailed Implementation

[0029] In this application, the terms "set up," "equipped with," and "connected" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0031] The Battery Management System (BMS) is the core unit for monitoring and controlling low-voltage energy storage battery packs, responsible for ensuring battery safety, extending lifespan, and improving available energy and system efficiency. Existing low-voltage BMS heating power supply circuits often use diodes as rectification, freewheeling, or reverse connection protection components. However, the inherent forward voltage drop of diodes leads to significant conduction losses. In low-temperature environments, the battery's usable power is limited, and any unnecessary losses will reduce the system's thermal efficiency and range, prolong preheating time, and negatively impact the user experience and energy efficiency of the vehicle or energy storage system.

[0032] Based on the aforementioned technical problems, this application provides a heating power supply circuit. Since the first terminals of two first switching units Q1 are connected together, the two controlled conducting switches can achieve synchronous conduction and cutoff as long as the signals at the control terminals are consistent. At this time, the controlled conducting switches of both first switching units Q1 are in the off state. Because the two unidirectional conducting switches of the two first switching units Q1 are opposite, one of the unidirectional conducting switches provides instantaneous reverse connection protection. Thus, this application can provide reverse connection protection by adding a new first switching unit Q1. Simultaneously, the newly added first switching unit Q1 has lower conduction losses due to the controlled conducting switch losses compared to the unidirectional conducting switches, meaning the controlled conducting switch is a low-loss conducting switch. This effectively solves the loss caused by the fixed forward voltage drop of the diode in the original solution; thereby improving the circuit's output capability and thermal stability without significantly increasing size and cost.

[0033] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0034] In one embodiment, Figure 1 A schematic diagram of a load power supply circuit 200 provided in this application.

[0035] See Figure 1The heating power supply circuit includes a load power supply circuit 200 and two first switching units Q1. The load power supply circuit 200 is used to connect the load and the power supply, and the two first switching units Q1 are connected in series in the load power supply circuit 200.

[0036] It should be noted that the load power supply circuit 200 connects the power source and the load to form an electrical energy transmission path. The power source can be a low-voltage energy storage battery pack, and the load can be a heating film, heating element, or other temperature control element that requires power. One end of the load power supply circuit 200 is connected to the positive terminal of the power source, and the other end is connected to the load. The load is connected to the negative terminal of the power source. Electrical energy is delivered to the load through the load power supply circuit 200 to achieve the heating function. The two first switch units Q1 play the role of conducting when connected in the correct direction and blocking when connected in the reverse direction to ensure system safety.

[0037] Specifically, the first switching unit Q1 includes a controlled conducting switch and a unidirectional conducting switch. The controlled conducting switch includes a first terminal, a second terminal, and a control terminal. The controlled conducting switch is used to turn on / off based on the control signal received by the control terminal. When the control terminal receives the control signal, the controlled conducting switch turns on when the voltage difference between the control terminal and the first terminal is satisfied. The first terminals of the two first switching units Q1 are connected together. The unidirectional conducting switch is connected in parallel with the controlled conducting switch and is used to turn on when there is a preset voltage difference between the first terminal and the second terminal. The conduction loss of the controlled conducting switch is less than that of the unidirectional conducting switch.

[0038] For example, under normal operating conditions, the controlled terminal receives the control signal from the controller, creating a conduction voltage difference between the control terminal and the first terminal of the controlled on-switch. The controlled on-switch then conducts, allowing current to flow to the load. In its on-state, the controlled on-switch is typically configured to primarily exhibit resistive losses, with its on-resistance (RDS(on)) selectable to the milliohm level, significantly lower than the conduction losses of a unidirectional on-switch, thus substantially reducing circuit voltage drop and heat generation. This effectively solves the loss caused by the fixed forward voltage drop of the diode in the original solution, thereby improving the circuit's output capability and thermal stability without significantly increasing size and cost.

[0039] When the positive and negative terminals of the external power supply are reversed, since the current flows from the second terminal to the first terminal of the unidirectional conduction switch of the first switching unit Q1, when the first terminals of the controlled conduction switches of the two first switching units Q1 are connected together, the unidirectional conduction switch of one of the first switching units Q1 functions to cut off the current. Therefore, when the external power supply is reversed, the unidirectional conduction switch of one of the first switching units Q1 blocks the current due to reverse cutoff, thereby preventing the instantaneous current of reverse connection from passing through and realizing the instantaneous reverse connection protection function. This structure achieves low conduction loss while ensuring the reliability of reverse connection protection, without the need for additional independent reverse protection devices, which helps to simplify circuit design and improve system integration.

[0040] It should be noted that the BMS system is equipped with a reverse power connection detection circuit. When the reverse power connection detection circuit detects that the external power is reversed, it will trigger the controller to cut off the control signal, so that the controlled conducting switches in the two first switching units Q1 are both in the open state, and one of the two unidirectional conducting switches is cut off due to reverse bias, completely blocking the loop current path and playing a momentary reverse protection function.

[0041] To clearly demonstrate the above reverse connection protection function Figure 2 A schematic diagram of a reverse connection protection structure for a power supply circuit 200 is provided. Figure 2 The diagram shows the current path when the power supply is reversed. At this time, the positive terminal of the power supply is connected to the negative terminal of the load power supply circuit 200, and the negative terminal of the power supply is connected to the positive terminal. Although one of the unidirectional conduction switches is forward biased, the other unidirectional conduction switch is in the reverse cut-off state, forming a high blocking circuit. The entire circuit cannot form an effective current path, and the current cannot flow, thereby achieving reliable reverse connection protection.

[0042] In one embodiment, the on-resistance of the unidirectional conduction switch can be greater than that of the controlled conduction switch. In specific applications, the controlled conduction switch can be a resistive loss element with low RDS(on); the unidirectional conduction switch can be a device with a higher equivalent on-resistance, such as a diode, which has an equivalent fixed forward voltage drop and a small-signal equivalent resistance much higher than that of the controlled conduction switch. When the unidirectional conduction switch uses an active device with unidirectional characteristics, by limiting its gate-source bias or selecting a version with a higher RDS(on), its equivalent on-resistance is made significantly greater than that of the controlled conduction switch when conducting. Through the above parameter configuration, a parallel relationship is formed between a low-resistance main channel and a high-resistance secondary channel. During normal operation, the controlled conduction switch takes priority due to the on-voltage difference, carrying the main current with low resistance, significantly reducing conduction losses.

[0043] In one embodiment, the unidirectional switching switch is a diode, and the controlled switching switch is an active switch. The diode, as a unidirectional switching switch, ensures rapid blocking of the reverse current path when the power supply is reversed due to its forward conduction characteristic. The active switch, upon receiving a drive signal at the control terminal, conducts with extremely low RDS(on) under normal operating conditions, achieving efficient energy transfer. Since the equivalent on-resistance of the diode is much higher than that of the active switch, current preferentially flows through the active switch, thereby constructing a low-loss main channel.

[0044] It should be noted that an active switch usually refers to a "controllable switch" implemented by a semiconductor device that requires external driving or has its own control circuit. Active switches rely on active driving to quickly switch between conduction and turn-off, such as MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) and IGBT (Insulated Gate Bipolar Transistor).

[0045] In one embodiment, the first switching unit Q1 includes a MOSFET, with a first terminal, a second terminal, and a control terminal being the source, drain, and gate of the MOSFET, respectively; a unidirectional conduction switch is the body diode of the MOSFET, and a controlled conduction switch is the source-drain conduction channel of the MOSFET.

[0046] For example, this application uses a MOSFET to simultaneously realize the functions of a unidirectional conduction switch and a controlled conduction switch. The body diode of the MOSFET acts as a passive unidirectional channel, and the source-drain channel of the MOSFET acts as a low-resistance main path, thereby reducing the number of independent diodes and other devices and improving the integration.

[0047] In one embodiment, the first switching unit Q1 can be a PMOS transistor. PMOS transistors are easier to drive; they can be turned on simply by pulling the gate low, without needing to provide a gate voltage higher than the power supply. This results in a simpler control circuit and lower cost.

[0048] It should be noted that the first switching unit Q1 can also be an NMOS transistor. In this case, it needs to be used in conjunction with a charge pump or bootstrap circuit to provide a gate drive voltage higher than the source, or other structures such as an ideal diode. This application does not limit this.

[0049] In one embodiment, see again Figure 1 The heating power supply circuit includes a first bias resistor R1 and / or a Zener diode D. The first bias resistor R1 is connected between the source and gate of the PMOS transistor, the anode of the Zener diode D is connected to the gate of the PMOS transistor, and the cathode of the Zener diode D is connected to the source of the PMOS transistor.

[0050] For example, the first bias resistor R1 provides an initial gate discharge path when the circuit starts up, ensuring reliable turn-off of the PMOS transistor and preventing the gate from being floating; the Zener diode D limits the voltage difference between the source and the gate, preventing device damage due to overvoltage. The Zener diode D and the first bias resistor R1 work together to ensure the safe start-up and shutdown of the PMOS transistor, while maintaining its stable conduction state during normal operation.

[0051] In one embodiment, see again Figure 1 The control terminals of the controlled on switches of the two first switching units Q1 are connected together and then connected to the same signal. This application achieves synchronous on / off switching of the two first switching units Q1, simplifies control, and enables unified shutdown in abnormal situations, thereby improving safety.

[0052] In one embodiment, see again Figure 1The heating power supply circuit also includes a voltage divider resistor R3, which is connected in series between the gate of the PMOS transistor and the control signal. It is used to adjust the voltage of the control signal input to the gate to prevent the gate-source voltage (the voltage difference between the gate and the source) of the PMOS transistor from exceeding the withstand voltage limit due to excessive control signal. At the same time, it improves signal compatibility and adapts to control sources with different levels.

[0053] In one embodiment, see again Figure 1 The heating power supply circuit also includes a second switching unit Q2. One end of the second switching unit Q2 is connected to the negative terminal of the power supply, and the other end of the second switching unit Q2 is connected to the control terminal. The controlled terminal of the second switching unit Q2 is used to connect to the controller to receive control signals. Under the control of the control signals, the control terminal of the first switching unit Q1 is connected or disconnected from the negative terminal of the power supply by turning on / off, thereby controlling the voltage difference between the control terminal of the first switching unit Q1 and the first terminal of the first switching unit Q1 to realize the controlled switching on / off.

[0054] This application further configures a second switching unit Q2 as a control-level switch, driven by a control signal (e.g., PWM) output by the controller to achieve precise timing control of the first switching unit Q1. When the second switching unit Q2 receives the level signal output by the controller and turns on, it pulls down the control terminal potential shared by the two first switching units Q1, causing the gate-source voltage difference of the PMOS transistor to reach the conduction threshold, thereby opening the controlled conduction channel; when turned off, it cuts off the discharge circuit and maintains a high-impedance state.

[0055] In one embodiment, the second switching unit Q2 can be an NMOS transistor. Specifically, the drain of the NMOS transistor is connected to the common control terminal of the first switching unit Q1, the source is grounded or connected to the negative terminal of an external power supply, and the gate receives the control signal output by the controller. Since the NMOS transistor acts as a low-side pull-down device, it ensures full conduction when the controller is high, exhibiting low on-resistance and good switching characteristics, which helps reduce power consumption and voltage loss in the control loop and improve overall energy efficiency. Simultaneously, its driving logic is naturally compatible with the digital controller, facilitating high-frequency switching operations.

[0056] It should be noted that the second switching unit Q2 can also adopt other structures with similar functions, such as PMOS transistors, and this application does not limit this.

[0057] It should be noted again that a second bias resistor R5 is connected between the source and gate of the second switching unit Q2 to provide a definite default off state. When the controlled terminal of the second switching unit Q2 is floating, powered off, or reset, the gate is pulled towards the source through this resistor, so that the gate-source voltage difference tends to 0, thus avoiding accidental conduction.

[0058] In one embodiment, see again Figure 1The heating power supply circuit also includes a current-limiting resistor R7 and / or a filter unit C. The gate of the NMOS transistor is connected to the controller via the current-limiting resistor R7, and the filter unit C is connected between the gate and source of the NMOS transistor.

[0059] For example, the second switching unit Q2 is an NMOS transistor, whose gate is connected to the controller output terminal through a current-limiting resistor R7. The current-limiting resistor R7 is used to suppress the transient current surge of the switch and prevent the drive signal from oscillating. The filter unit C is composed of a capacitor or an RC network and is connected between the gate and source of the NMOS transistor. It is used to filter out high-frequency noise, improve anti-interference capability, and ensure stable and reliable switching operation.

[0060] In one embodiment, see Figure 3 and Figure 4 The heating power supply circuit also includes a first output terminal for connecting to the positive terminal of the load and a second output terminal for connecting to the negative terminal of the load. The heating power supply circuit includes a voltage detection unit connected between the first output terminal and the second output terminal for detecting the output voltage between the first output terminal and the second output terminal and outputting it to the controller, so that the controller outputs a control signal to the control terminal according to the output voltage to turn on / off the controlled on / off switch; and / or a current detection unit connected in series in the load power supply circuit 200 for detecting the power supply current in the load power supply circuit 200 and outputting it to the controller, so that the controller outputs a control signal to the control terminal according to the power supply current to turn on / off the controlled on / off switch.

[0061] For example, the voltage detection unit monitors the voltage change at the first output terminal in real time. When the output voltage deviates from the set threshold, the controller dynamically adjusts the level signal to maintain output stability. The current detection unit obtains the load current in real time through a sampling resistor to prevent overcurrent or short circuit from damaging the device. The controller combines voltage and current feedback information to achieve closed-loop control, improving the accuracy and safety of the heating process. It realizes real-time control of output voltage and supply current, enabling constant voltage / constant current / current limiting operating modes, and improving the stability and accuracy of heating power.

[0062] In one embodiment, see Figure 5 The heating power supply circuit includes an overcurrent protection device connected in series in the power supply circuit 200, which is used to disconnect the circuit when the current in the power supply circuit 200 exceeds a preset threshold.

[0063] For example, an overcurrent protection device is connected in series in the load power supply circuit 200 to automatically disconnect the circuit when the current in the power supply circuit 200 exceeds a preset threshold, thereby achieving hardware-level overcurrent / short-circuit protection and preventing damage to the controlled switching, load, and power supply. The overcurrent protection device may be a one-time fuse, a resettable fuse (PPTC), an electronic overcurrent circuit breaker module, or a combination of several of these.

[0064] In one embodiment, the first switching unit Q1 of this application may adopt the structure of an ideal diode to further reduce the circuit space occupied, such as the LM66100 ideal diode. This application does not limit this.

[0065] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0066] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0067] The above description is only a specific embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A heating power supply circuit, characterized in that, This includes a load power supply circuit for connecting the load and the power source, and two first switching units connected in series in the circuit, each first switching unit comprising: A controlled on / off switch includes a first terminal, a second terminal, and a control terminal. The controlled on / off switch is used to turn on / off based on a control signal received by the control terminal. The first terminals of the two first switch units are connected together. A unidirectional conduction switch, connected in parallel with the controlled conduction switch, is used to conduct when there is a preset voltage difference between the first end and the second end; The conduction loss of the controlled conduction switch is less than that of the unidirectional conduction switch.

2. The heating power supply circuit according to claim 1, characterized in that, The unidirectional conduction switch is a diode, and the controlled conduction switch is an active switch.

3. The heating power supply circuit according to claim 1, characterized in that, The first switching unit includes a MOSFET, with the first terminal, the second terminal, and the control terminal being the source, drain, and gate of the MOSFET, respectively; the unidirectional conduction switch is the body diode of the MOSFET, and the controlled conduction switch is the source-drain conduction channel of the MOSFET.

4. The heating power supply circuit according to claim 1, characterized in that, The first switching unit is a PMOS transistor.

5. The heating power supply circuit according to claim 4, characterized in that, The heating power supply circuit includes a first bias resistor and / or a Zener diode. The first bias resistor is connected between the source and gate of the PMOS transistor. The anode of the Zener diode is connected to the gate of the PMOS transistor, and the cathode of the Zener diode is connected to the source of the PMOS transistor.

6. The heating power supply circuit according to claim 1, characterized in that, The control terminals of the controlled conducting switches of the two first switching units are connected together and then connected to the same signal.

7. The heating power supply circuit according to claim 1, characterized in that, The heating power supply circuit also includes: The second switching unit has one end connected to the negative terminal of the power supply and the other end connected to the control terminal. The controlled terminal of the second switching unit is used to connect to the controller to receive the control signal. Under the control of the control signal, the controller controls the connection or disconnection between the control terminal and the negative terminal of the power supply by turning the switch on or off, thereby controlling the voltage difference between the control terminal and the first terminal to turn the controlled switch on or off.

8. The heating power supply circuit according to claim 7, characterized in that, The second switching unit is an NMOS transistor.

9. The heating power supply circuit according to claim 8, characterized in that, The heating power supply circuit includes a current-limiting resistor and / or a filter unit. The gate of the NMOS transistor is connected to the controller via the current-limiting resistor, and the filter unit is connected between the gate and source of the NMOS transistor.

10. The heating power supply circuit according to claim 1, characterized in that, The heating power supply circuit includes a first output terminal for connecting to the positive terminal of the load and a second output terminal for connecting to the negative terminal of the load. The heating power supply circuit includes: A voltage detection unit is connected between the first output terminal and the second output terminal to detect the output voltage between the first output terminal and the second output terminal and output it to the controller, so that the controller outputs the control signal to the control terminal according to the output voltage, thereby turning on / off the controlled on switch. And / or, a current detection unit is connected in series in the load power supply circuit to detect the power supply current in the load power supply circuit and output it to the controller, so that the controller outputs the control signal to the control terminal according to the power supply current, thereby turning on / off the controlled on switch.

11. The heating power supply circuit according to claim 1, characterized in that, The heating power supply circuit includes: An overcurrent protection device is connected in series in the power supply circuit to disconnect when the current in the power supply circuit exceeds a preset threshold.

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