Control method and device of voltage conversion circuit and electronic equipment

Abstract

A control method of a voltage conversion circuit, comprising: acquiring an actual output voltage of the voltage conversion circuit; determining a reference current of the voltage conversion circuit according to the actual output voltage of the voltage conversion circuit and a load operating voltage; determining a working condition of the voltage conversion circuit according to the reference current; when the working condition of the voltage conversion circuit is light load, acquiring a first voltage difference across an inductor and an inductor value; determining a first duty cycle according to the reference current, the first voltage difference and the inductor value; generating a first driving signal according to the first duty cycle and outputting a first off signal, the first driving signal being used for controlling on-off of a main switch in a bridge arm unit, and the first off signal being used for controlling the freewheeling switch in the bridge arm unit to keep off.

Description

Technical Field

[0001] This application relates to the technical field of electronic circuits, and more particularly to a control method, apparatus, and electronic device for a voltage conversion circuit. Background Technology

[0002] The statements herein are provided only as background information in connection with this application and do not necessarily constitute exemplary technology.

[0003] Currently, voltage conversion circuits comprising one or more bridge arms typically output different voltages by controlling the on / off states of the upper and lower switching transistors within the bridge arms. However, the current control method for the upper and lower switching transistors is prone to causing output voltage fluctuations when different voltages are output. Summary of the Invention

[0004] This application provides a control method, apparatus, and electronic device for a voltage conversion circuit.

[0005] In a first aspect, this application provides a control method for a voltage conversion circuit, the voltage conversion circuit including an inductor for energy storage and a bridge arm unit for power conversion; the bridge arm unit includes two switching transistors connected in series; a first end of the inductor is connected between the two switching transistors, the method comprising:

[0006] Obtain the actual output voltage of the voltage conversion circuit;

[0007] The reference current of the voltage conversion circuit is determined based on the actual output voltage of the voltage conversion circuit and the load operating voltage.

[0008] The operating condition of the voltage conversion circuit is determined based on the reference current;

[0009] When the voltage conversion circuit is operating under light load, the first voltage difference across the inductor and the inductance value are obtained.

[0010] The first duty cycle is determined based on the reference current, the first voltage difference, and the inductance value.

[0011] A first drive signal is generated based on the first duty cycle, and a first turn-off signal is output; the first drive signal is used to control the on / off state of the main switch in the bridge arm unit, and the first turn-off signal is used to control the freewheeling switch in the bridge arm unit to remain off.

[0012] Secondly, this application also provides a voltage conversion device, which includes a voltage conversion circuit and a controller;

[0013] The controller is connected to the controlled terminals of each switching transistor in the voltage conversion circuit, and the controller is used to implement the control method as described in the embodiments of this application.

[0014] Thirdly, this application also provides an electronic device, which includes a voltage conversion device as described in the embodiments of this application.

[0015] Fourthly, this application also provides a storage medium storing one or more computer programs, which can be executed by one or more processors to implement the control method as described in the embodiments of this application.

[0016] Details of one or more embodiments of this application are set forth in the following drawings and description. Other features, objects, and advantages of this application will become apparent from the specification, drawings, and claims. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments or exemplary technologies of this application, the accompanying drawings used in the description of the embodiments or exemplary technologies will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A circuit diagram of a voltage conversion circuit provided in an embodiment of this application;

[0019] Figure 2 This is a circuit diagram of a voltage conversion circuit provided in an embodiment of this application;

[0020] Figure 3 This is a circuit diagram of another voltage conversion circuit provided in an embodiment of this application;

[0021] Figure 4 This is a flowchart illustrating the steps of a control method for a voltage conversion circuit provided in an embodiment of this application.

[0022] Figure 5 A flowchart illustrating the steps of another control method for a voltage conversion circuit provided in an embodiment of this application;

[0023] Figure 6 A schematic diagram illustrating the voltage control loop provided in this embodiment;

[0024] Figure 7 A schematic diagram of the current control loop provided in this embodiment;

[0025] Figure 8 A schematic block diagram of a voltage conversion device provided in this application embodiment;

[0026] Figure 9This is a schematic block diagram of the structure of an electronic device provided in an embodiment of this application.

[0027] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0030] This application provides a control method, apparatus, electronic device, and storage medium for a voltage conversion circuit. The control method for the voltage conversion circuit can be applied to a voltage conversion device, which includes a voltage conversion circuit and a controller, through which the controller can control the voltage conversion circuit.

[0031] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0032] Please refer to Figure 1 , Figure 1 This is a circuit diagram of a voltage conversion circuit provided in an embodiment of this application.

[0033] like Figure 1As shown, the voltage conversion circuit 100 includes an inductor L for energy storage and a bridge arm unit 110 for power conversion. The bridge arm unit 110 includes two series-connected switching transistors SW1 and SW2, each containing a diode D connected in reverse parallel. The first end of the inductor L is connected between the two switching transistors SW1 and SW2, and the second end of the inductor L is used to receive DC power or connect a load. The inductor L and the bridge arm unit 110 form a boost circuit or a buck circuit. It is understood that the switching transistors SW1 and SW2 may include power transistors (GTRs), power MOSFETs, or insulated-gate transistors (IGBTs), etc., and each of these transistors includes a body diode. In other embodiments, the switching transistors SW1 and SW2 may also be formed by a transistor and a diode connected in parallel; this application does not limit this. The two series-connected switching transistors SW1 and SW2 include a main switch and a freewheeling switch; for example, the upper switch SW1 is the main switch, and the lower switch SW2 is the freewheeling switch.

[0034] To reduce conduction losses, the voltage conversion circuit 100 can be controlled in different ways under different operating conditions, with variations in the control methods for the two series-connected switches SW1 and SW2. For example, when the voltage conversion circuit 100 is under heavy load, the upper switch SW1 and the lower switch SW2 need to be controlled to generate complementary waveforms. When the voltage conversion circuit 100 is under light load, the on-time of the upper switch SW1 needs to be controlled, and the lower switch SW2 needs to be kept normally closed. This reduces circuit losses.

[0035] However, the applicant discovered that when the operating conditions of the voltage conversion circuit 100 change, such as when the operating conditions of the voltage conversion circuit 100 switch from heavy load to light load, using the same duty cycle to control the switching transistor Q1 as during heavy load will cause fluctuations in the output voltage and make it impossible to provide a stable voltage.

[0036] Based on this, the embodiments of this application determine the operating condition of the voltage conversion circuit 100 by determining the reference current of the voltage conversion circuit 100. When the voltage conversion circuit 100 is operating under light load, the first voltage difference across the inductor L and the inductance value are further obtained. A first duty cycle is calculated based on the reference current, the first voltage difference, and the inductance value. A first drive signal is generated according to the first duty cycle, and a first turn-off signal is output. The first drive signal is used to control the on / off of the main switch in the bridge arm unit 110, and the first turn-off signal is used to control the freewheeling switch in the bridge arm unit 110 to remain off. Using the method of this application, the output voltage of the voltage conversion circuit 100 can be precisely controlled while reducing circuit losses, reducing output voltage fluctuations, and enabling the voltage conversion circuit 100 to provide a stable output voltage.

[0037] For example, the voltage conversion circuit includes, as shown below: Figure 2 The diagram shows a half-bridge buck converter. This half-bridge buck converter includes an inductor L1 for energy storage and two series-connected switching transistors Q1 and Q2. The second terminal of transistor Q1 is connected to the first terminal of transistor Q2. The series connection of transistors Q1 and Q2 forms a bridge arm unit for power conversion. Figure 2 As shown, the switching transistors Q1 and Q2 can be MOSFETs. Each MOSFET includes a body diode, which is connected in series between the first and second terminals of the switching transistor. Figure 2 The diagram shows body diodes D1 and D2. The first terminal of inductor L1 is connected to the second terminal of switching transistor Q1, and the second terminal of inductor L1 is used to connect the load R1. The load R1 is connected in parallel with capacitor C2, which is used to filter the current output by inductor L1. Capacitor C1 is connected across the bridge arm unit formed by switching transistors Q1 and Q2; capacitor C1 is an energy storage capacitor, also known as a bus capacitor. Inductor L1 and the two series-connected switching transistors Q1 and Q2 form a half-bridge buck circuit. The bus voltage at capacitor C1 supplies power to the load R1 after passing through the half-bridge buck circuit.

[0038] For example, the voltage conversion circuit includes, as shown below: Figure 3 The diagram shows a bidirectional buck-boost circuit. This circuit includes an inductor L2 for energy storage and two bridge arm units. Each bridge arm unit includes two series-connected switches Q1 and Q2, and two series-connected switches Q3 and Q4. The series-connected switches Q1 and Q2 form the first bridge arm unit, and the series-connected switches Q3 and Q4 form the second bridge arm unit. The first terminal of inductor L2 is connected to the second terminal of switch Q1, and the second terminal of inductor L2 is connected to the second terminal of switch Q3. The first terminal of switch Q3 is used to connect to the second terminal of switch Q4 through a load R2. The load R2 is connected in parallel with a capacitor C4, which filters the current output from the first terminal of switch Q3. Similarly, as... Figure 3 As shown, each switch is a MOSFET, and therefore includes a reverse-biased body diode, such as... Figure 3 The body diodes D1, D2, D3, and D4 are shown. Capacitor C3 is an energy storage capacitor, also known as the bus capacitor. Inductor L2 and the two bridge arm units constitute a step-up / step-down circuit. The output voltage of capacitor C3 supplies power to the load R2 through the bidirectional step-up / step-down circuit, or the voltage at capacitor C4 supplies power to the load at capacitor C3 through the bidirectional step-up / step-down circuit. Figure 3 Power supply (not shown in the image).

[0039] It is understandable that when the voltage conversion circuit 100 is as follows... Figure 3In the bidirectional buck-boost circuit shown, power conversion is performed by different bridge arm units in different operating modes. For example, taking the side containing capacitor C3 as the input side and the side containing capacitor C4 as the output side, when the bidirectional buck-boost circuit operates in buck mode, the first bridge arm unit formed by switches Q1 and Q2 is used for power conversion, switch Q3 remains on, and switch Q4 remains off. When the bidirectional buck-boost circuit operates in boost mode, the second bridge arm unit formed by switches Q3 and Q4 is used for power conversion, switch Q1 remains on, and switch Q2 remains off.

[0040] It's understandable, when Figure 3 In the voltage conversion circuit shown, when switch Q1 remains on and switch Q2 remains off, or when switch Q3 remains on and switch Q4 remains off, its working principle is the same as... Figure 2 Similarly, this will not be repeated here. Further details will follow. Figure 2 The control method of the voltage conversion circuit in this application will be described using an example.

[0041] For example Figure 2 Taking the step-down circuit shown as an example, when the circuit is under heavy load, it is necessary to control the upper switch Q1 and the lower switch Q2 to generate complementary waveforms to meet the heavy load requirements. However, when the circuit switches from heavy load to light load, if the control method of switches Q1 and Q2 is not changed, it will not only lead to circuit losses, but also cause fluctuations in the output voltage, making it impossible to provide a stable voltage. Therefore, this application provides a control method for a voltage conversion circuit to solve the above problems.

[0042] Please refer to Figure 4 , Figure 4 This is a flowchart illustrating the steps of a control method for a voltage conversion circuit provided in an embodiment of this application. The control method is used to control the voltage conversion circuit and includes steps S101 to S106.

[0043] Step S101: Obtain the actual output voltage of the voltage conversion circuit.

[0044] The second terminal of the inductor is used to receive DC power or to connect a load. Figure 2 Taking the half-bridge buck circuit shown as an example, when this circuit is used as a half-bridge buck circuit, the second terminal of the inductor is connected to the load, for example, as shown. Figure 2As shown in the diagram, with load R1, it can be understood that capacitor C2 is the output capacitor, and the actual output voltage of the voltage conversion circuit is the voltage across capacitor C2. When this circuit is used as a boost circuit, capacitor C2 connected to the second end of the inductor provides DC power to the circuit, and capacitor C1 is the output capacitor. In this case, load R1 can be connected to both sides of capacitor C1, and it can be understood that the actual output voltage of the voltage conversion circuit is the voltage across capacitor C1.

[0045] In this step, the actual output voltage can be acquired through a voltage sampling circuit. For example, the supply voltage at the output terminal can be acquired through a voltage sampling circuit or a voltage sampling sensor to obtain the actual output voltage of the voltage conversion circuit. This application does not limit the specific voltage sampling method.

[0046] Step S102: Determine the reference current of the voltage conversion circuit based on the actual output voltage of the voltage conversion circuit and the load operating voltage.

[0047] The load operating voltage is the target value of the output voltage of the voltage conversion circuit, and it can be preset according to actual conditions. The reference current of the voltage conversion circuit can be calculated using a deviation adjustment algorithm.

[0048] In this step, the reference current of the voltage conversion circuit is obtained by calculating the load operating voltage and the actual output voltage. This reference current is, for example, the output current corresponding to the adjustment of the output voltage of the voltage conversion circuit.

[0049] Step S103: Determine the operating condition of the voltage conversion circuit based on the reference current.

[0050] The voltage conversion circuit operates under both heavy load and light load conditions. In related technologies, the operating conditions may also include full load and no load. In this embodiment, heavy load may include full load, and light load may include no load. The operating conditions of the voltage conversion circuit can be determined using a reference current.

[0051] For example, the current conduction mode of the inductor is determined based on the reference current, which includes continuous current mode and discontinuous current mode; the operating condition of the voltage conversion circuit is determined based on the current conduction mode, and there is a correspondence between the current conduction mode and the operating condition of the voltage conversion circuit.

[0052] It should be noted that the continuous current mode indicates that the current through the inductor is continuous and uninterrupted, while the discontinuous current mode indicates that the current through the inductor is discontinuous and intermittent. The voltage conversion circuit operates in continuous current mode under heavy load, and in discontinuous current mode under light load.

[0053] Step S104: When the voltage conversion circuit is operating under light load, obtain the first voltage difference across the inductor and the inductance value.

[0054] In this step, the voltage difference across the inductor can be obtained through a voltage sampling circuit or a voltage sensor to obtain the first voltage difference; or the input voltage of the inductor and the output voltage of the voltage conversion circuit can be sampled separately, and the first voltage difference across the inductor can be determined by calculating the difference between the input voltage and the output voltage of the inductor.

[0055] In this step, the inductance value can be tested using an inductance tester; or the inductive reactance can be calculated using Ohm's law by obtaining the voltage and current through the inductor, and then the inductance value can be derived according to the inductive reactance formula.

[0056] In other embodiments, the inductance value can also be stored directly in the memory after the circuit design is completed, and the controller can retrieve it directly from the memory.

[0057] Step S105: Determine the first duty cycle based on the reference current, the first voltage difference, and the inductance value.

[0058] In this step, the first duty cycle can be calculated based on the reference current, the first voltage difference, and the inductance value. When the voltage conversion circuit is lightly loaded, it is necessary to control the on-time of the upper switching transistor (main switching transistor) and keep the lower switching transistor (freewheeling switching transistor) normally closed. Therefore, this first duty cycle is mainly used to control the on-time of the upper switching transistor. Figure 2 For example, in light-load mode, when the upper switch Q1 is turned on, the inductor current gradually increases, and the voltage gradually increases. At the instant the upper switch Q1 is turned off, the first voltage difference across the inductor and the inductor current I... L When all values ​​reach their maximum, this maximum value is also the target output current that the voltage conversion circuit needs to achieve in light-load mode. Therefore, this maximum value can be considered as the reference current. Thus, based on the volt-ampere relationship of the inductor, the conduction time of the upper switch Q1 can be calculated based on this reference current, the first voltage difference, and the inductance value. Once the conduction time of the upper switch Q1 is determined, the first duty cycle can be determined.

[0059] Step S106: Generate a first drive signal according to the first duty cycle and output a first turn-off signal.

[0060] The bridge arm unit contains two switches connected in series: a main switch and a freewheeling switch. In this step, a first drive signal is used to control the on / off state of the main switch in the bridge arm unit, and a first turn-off signal is used to keep the freewheeling switch in the bridge arm unit off. Figure 2 Taking the circuit shown as an example, the upper switch Q1 is the main switch, and the lower switch Q2 is the freewheeling switch.

[0061] It should be noted that turning off the freewheeling switch when the voltage conversion circuit is switched to a light load can effectively reduce the current of the voltage conversion circuit. At this time, the current through the inductor will also decrease. Compared with the freewheeling switch being turned on, this can effectively reduce the overall loss in the circuit.

[0062] The control method for the voltage conversion circuit provided in the above embodiment determines the duty cycle of the drive signal of the main switch transistor directly based on the reference current, inductance value, and voltage difference across the inductor when the operating condition of the voltage conversion circuit is light load. This controls the on / off state of the main switch transistor while keeping the continuous current switch transistor off. This reduces light load losses and precisely regulates the output voltage of the voltage conversion circuit, reducing output voltage fluctuations.

[0063] Please refer to Figure 5 , Figure 5 This is a flowchart illustrating the steps of another control method for a voltage conversion circuit provided in an embodiment of this application.

[0064] like Figure 5 As shown, the control method for this voltage conversion circuit includes steps S201 to S209. The following description combines this control method with the above... Figure 2 The step-down circuit shown will be used as an example for further explanation.

[0065] Step S201: Obtain the actual output voltage of the voltage conversion circuit.

[0066] In this circuit, the actual output voltage can be the supply voltage provided to the load. For example... Figure 2 As shown, load R1 is connected in parallel with capacitor C2, and the voltages across load R1 and capacitor C2 are equal. The actual output voltage of the voltage conversion circuit can be the voltage across capacitor C2. The voltage across capacitor C2 can be obtained by sampling the voltage difference across capacitor C2 using a voltage sampling circuit.

[0067] Step S202: Determine the reference current of the voltage conversion circuit based on the actual output voltage of the voltage conversion circuit and the load operating voltage.

[0068] The load operating voltage can be set according to actual conditions, for example... Figure 2 As shown, the voltage V2 of capacitor C2 can be used as the actual output voltage. By performing negative feedback calculation on the load operating voltage and the actual output voltage, the reference current of the voltage conversion circuit can be obtained. This reference current is, for example, the output current of the voltage conversion circuit at the next moment.

[0069] In some embodiments, step S202 includes: calculating the difference between the actual output voltage and the load operating voltage to obtain a second voltage difference; and determining a reference current based on the second voltage difference and a first deviation adjustment algorithm.

[0070] The first deviation adjustment algorithm can be a P-adjustment algorithm (Proportional control), a PI-adjustment algorithm (Proportional-Integral control), a PID-adjustment algorithm (Proportion-Integral-Derivative control), or other adjustment algorithms. The first deviation adjustment algorithm can accurately determine the reference current of the voltage conversion circuit based on the second voltage difference.

[0071] For example, such as Figure 6 As shown, the actual output voltage V2 is compared with the load operating voltage V. 2Ref The input is fed into subtractor 210, which calculates the actual output voltage V2 and the load operating voltage V. 2Ref The difference between them yields the second voltage difference (V2-V). 2Ref The PI controller 220 uses the first deviation adjustment algorithm to adjust the second voltage difference (V2-V). 2Ref The voltage is converted to obtain the reference current I of the voltage conversion circuit. ref .

[0072] It should be noted that the process of determining the reference current of the voltage conversion circuit based on the actual output voltage and the load operating voltage can be a closed-loop control process, such as... Figure 6 The control loop shown can be a voltage control loop, which uses the second voltage difference between the actual output voltage and the load operating voltage as the voltage deviation to calculate the closed-loop regulation of the reference current.

[0073] Step S203: Determine the operating condition of the voltage conversion circuit based on the reference current.

[0074] As mentioned earlier, the voltage conversion circuit operates under heavy load when the inductor enters continuous current mode, and under light load when the inductor enters discontinuous current mode. Therefore, the operating condition of the voltage conversion circuit can be accurately determined based on the reference current and the preset current value.

[0075] In some embodiments, if the reference current is less than or equal to a preset current value, the voltage conversion circuit is determined to be operating under light load; if the reference current is greater than the preset current value, the voltage conversion circuit is determined to be operating under heavy load.

[0076] The preset current value is the critical current value for the inductor to switch from continuous current mode to discontinuous current mode. The critical current value is used to indicate the critical condition for the inductor to maintain continuous current.

[0077] In one embodiment, the critical current value is obtained by: acquiring the input voltage of the voltage conversion circuit and acquiring the switching period of the main switch; calculating the voltage difference between the input voltage and the actual output voltage, and multiplying the voltage difference by the actual output voltage to obtain a target product value; calculating the product between the input voltage and the inductance value of the inductor to obtain a third product value; calculating the ratio between the target product value and the third product value, and multiplying the ratio by the switching period of the main switch to obtain the critical current value.

[0078] It should be noted that by calculating the critical current value at which the inductor transitions from continuous current mode to discontinuous current mode, the operating condition of the voltage conversion circuit can be accurately determined. This allows for precise control of the output voltage of the voltage conversion circuit under different operating conditions, thereby reducing output voltage fluctuations.

[0079] For example, such as Figure 2 As shown, under the critical condition that the current in inductor L1 is continuous, the inductor current I during the conduction phase of the main switch Q1 is... L The current continues to rise. After the main switch Q1 is turned on, the current rise phase begins. When the inductor current reaches its highest point, the following applies to the inductor:

[0080] I L = (V1-V2) / L*Tonmax (1);

[0081] Where Tonmax is the maximum on-time of the main switch Q1, L is the inductance of inductor L1, V1 is the input voltage of the voltage conversion circuit, and V2 is the actual output voltage. After the main switch Q1 is turned off, the inductor current continuously decreases from its highest point until it reaches 0. Therefore, for the inductor, the following holds:

[0082] I L = (V2) / L*(Ts-Tonmax) (2);

[0083] Ts is the switching cycle of the main switch Q1.

[0084] Under the critical condition of continuous current, according to (1) and (2), we can obtain:

[0085]

[0086] Therefore, the maximum on-time for continuous current conduction can be calculated as follows:

[0087]

[0088] The critical current for an inductor to transition from continuous current mode to discontinuous current mode is:

[0089]

[0090] Step S204: When the voltage conversion circuit is operating under light load, obtain the first voltage difference across the inductor and the inductance value.

[0091] In one embodiment, obtaining the first voltage difference across the inductor includes: obtaining the input voltage of the voltage conversion circuit; calculating the voltage difference between the input voltage and the actual output voltage to obtain the first voltage difference.

[0092] The first terminal of the inductor is connected between the two switching transistors, and the second terminal is used to receive DC power or to connect a load. Therefore, the first voltage difference across the inductor can be obtained by calculating the voltage difference between the input voltage and the actual output voltage.

[0093] like Figure 2 As shown, the input voltage of the voltage conversion circuit can be the voltage V1 at capacitor C1, and the actual output voltage can be the voltage V2 at capacitor C2. Therefore, the voltage applied across inductor L is: V L =V1-V2.

[0094] In one embodiment, the inductance value of the inductor can be obtained by detecting it with an inductance tester, or it can be calculated based on the first voltage difference and the inductor current. This embodiment does not specifically limit this.

[0095] Step S205: Determine the first duty cycle based on the reference current, the first voltage difference, and the inductance value.

[0096] like Figure 2 As shown, when the voltage conversion circuit is lightly loaded, it is necessary to control the on-time of the main switch Q1 and control the freewheeling switch Q2 to remain normally closed. Therefore, the first duty cycle is mainly used to control the on-time of the main switch Q1.

[0097] In one embodiment, step S205 includes: obtaining the switching cycle of the main switch; determining a first ratio between the inductance value and the first voltage difference; calculating the product of the reference current and the first ratio; and determining a first duty cycle based on the ratio between the product and the switching cycle.

[0098] For example, the formula for calculating the first duty cycle is:

[0099]

[0100] Where Duty2 is the first duty cycle, Ts is the switching period of the main switch Q1, V1 is the actual output voltage of capacitor C1, V2 is the first voltage difference of capacitor C2, and I ref This is the reference current.

[0101] It should be noted that during the conduction period of the main switch Q1, there is an inductor voltage V. L=L*(di / dt), then dt = L*di / V L =L*Iref / (V1-V2). Therefore, the first duty cycle is:

[0102]

[0103] Step S206: Generate a first drive signal according to the first duty cycle and output a first turn-off signal.

[0104] The bridge arm unit contains two switches connected in series, including a main switch and a freewheeling switch. A first drive signal is used to control the on / off state of the main switch in the bridge arm unit, and a first turn-off signal is used to keep the freewheeling switch in the bridge arm unit off.

[0105] It should be noted that when the voltage conversion circuit is under no-load or light-load conditions, the current in the circuit is greatly affected by the on / off state of the switching transistor. In this case, turning off the freewheeling switch can significantly reduce the current in the circuit, thereby reducing overall circuit losses. For example, it can significantly reduce inductor losses. Maintaining the main switching transistor's normal on / off state, with its on-time determined by the first duty cycle, results in a more stable voltage output. Since the first duty cycle is directly determined based on the reference current, the first voltage difference, and the inductance value, this avoids using the same duty cycle to control the main switching transistor when the freewheeling switch is turned off as under heavy load, which would cause output voltage fluctuations.

[0106] Step S207: When the voltage conversion circuit is under heavy load, obtain the actual output current of the voltage conversion circuit.

[0107] In this step, the actual output current of the voltage conversion circuit can be obtained through a current sampling circuit. Alternatively, the actual output current of the voltage conversion circuit can be obtained by calculating the supply current to the load through the inductor using Ohm's law. This embodiment does not impose specific limitations on this method.

[0108] For example Figure 2 As shown, the actual output current is obtained by sampling the load R1 through a current sampling circuit. Alternatively, the current at the load R1 can be calculated based on the supply voltage and resistance of the load R1, and then used as the actual output current of the voltage conversion circuit.

[0109] Step S208: Determine the difference between the reference current and the actual output current to obtain the current difference.

[0110] Step S209: Determine the target voltage value based on the current difference and the second deviation adjustment algorithm.

[0111] When the voltage conversion circuit is under heavy load, the current in the circuit is mainly determined by the load. If the freewheeling switch is still turned off, the freewheeling current will flow through the body diode, increasing the conduction loss of the switch. Therefore, under heavy load, it is necessary to control the upper switch (main switch) and the lower switch (freewheeling switch) to conduct in a complementary manner. Thus, the second duty cycle is mainly used to control the conduction time of the upper and lower switches.

[0112] In some embodiments, the second duty cycle can be determined through closed-loop control of the current control loop. That is, the deviation between the actual output current and the desired output is obtained by subtracting the actual output current from the reference current using the actual output current as the feedback current. Then, a deviation adjustment algorithm is used for closed-loop control to determine the duty cycle at the next moment, so that the actual output current is stabilized at the target output current. As can be seen from the foregoing description, when the actual current is stabilized at the target output current, the closed-loop control in the voltage control loop will stabilize the output voltage at the load operating voltage. Thus, through closed-loop control of the voltage loop and the closed-loop control of the current loop, the output voltage of the voltage conversion circuit can be stabilized near the target voltage under heavy load conditions.

[0113] Step S210: Determine the second duty cycle based on the ratio between the target voltage value and the input voltage of the voltage conversion circuit.

[0114] The target voltage value is, for example, the target value Vpwm of the equivalent voltage at the midpoint between the main switch and the freewheeling switch at the next moment. The second deviation adjustment algorithm includes P-regulation, PI-regulation, PID-regulation algorithms, etc., and of course, other adjustment algorithms can also be used. The second deviation adjustment algorithm can accurately determine the target voltage value of the voltage conversion circuit based on the current difference.

[0115] For example, such as Figure 7 As shown, the reference current Iref and the current actual output current I1 are input to the subtractor 230. The subtractor 230 calculates the difference between the reference current Iref and the actual output current I1 to obtain the current difference I2. The PI controller 240 uses the second deviation adjustment algorithm to calculate the current difference I2 to obtain the target voltage value Vpwm for the next moment. The PWM controller 250 then calculates the second duty cycle Duty for the next moment based on the target voltage value Vpwm and the input voltage V1 of the voltage conversion circuit. k+1 =Vpwm / V1.

[0116] It should be noted that the process of determining the target voltage value of the voltage conversion circuit based on the reference current and the actual output current can be a closed-loop control process, such as... Figure 7 The control loop shown can be a current control loop, through, for example... Figure 6 The voltage control loop shown and as follows Figure 7The current control loop shown can realize closed-loop control of the output voltage of the voltage conversion circuit, thereby enabling accurate calculation of the second duty cycle.

[0117] Step S211: Generate a second drive signal and a third drive signal according to the second duty cycle.

[0118] The bridge arm unit consists of two switches connected in series: a main switch and a freewheeling switch. A second drive signal is used to turn the main switch of the bridge arm unit on and off, and a third drive signal is used to turn the freewheeling switch of the bridge arm unit on and off, so as to control the two switches in the bridge arm unit to conduct in a complementary manner.

[0119] The control method for the voltage conversion circuit provided in the above embodiments, when the voltage conversion circuit is under heavy load, obtains the actual output current of the voltage conversion circuit; determines a second duty cycle based on the reference current and the actual output current; and generates a second drive signal and a third drive signal based on the second duty cycle. The second drive signal is used to drive the main switch of the bridge arm unit to turn on and off, and the third drive signal is used to drive the freewheeling switch of the bridge arm unit to turn on and off, so as to control the two switches in the bridge arm unit to conduct complementaryly. In this embodiment, when the voltage conversion circuit is under heavy load, the actual output current is used as the feedback current to calculate the duty cycle of the main switch and the freewheeling switch, thereby controlling the on and off of the main switch and the freewheeling switch, so that the two switches in the bridge arm unit conduct complementaryly. This can accurately regulate the output voltage of the voltage conversion circuit, reduce output voltage fluctuations, and thus provide a stable output voltage and improve the control accuracy of the output voltage.

[0120] In the above embodiments, the control method for the voltage conversion circuit can also be applied to electronic devices. For example, the electronic device includes the voltage conversion circuit described above, which is connected directly or indirectly to various units in the electronic device to supply power to other units.

[0121] Please see Figure 8 , Figure 8 This is a schematic block diagram of a voltage conversion device provided in an embodiment of this application.

[0122] like Figure 8 As shown, the voltage conversion device 300 includes a voltage conversion circuit 310 and a controller 320. The controller 320 is connected to the controlled terminals of each switching transistor in the voltage conversion circuit 310, and is used to implement the control method of any voltage conversion circuit in the embodiments of this application. It should be noted that the voltage conversion circuit 310 can be the voltage conversion circuit 100 in the aforementioned embodiments.

[0123] In one embodiment, the voltage conversion circuit 310 is a half-bridge buck circuit. For example, a half-bridge buck circuit is as follows: Figure 2As shown, this half-bridge buck circuit includes an inductor L1 for energy storage and two series-connected switching transistors Q1 and Q2, which are used for power conversion. The inductor L1 and the two series-connected switching transistors Q1 and Q2 constitute the half-bridge buck circuit, and the output voltage of capacitor C1 supplies power to the load R1 after passing through the half-bridge buck circuit.

[0124] In one embodiment, the voltage conversion circuit 310 is a bidirectional buck-boost circuit, which includes a first bridge arm unit and a second bridge arm unit. The first bridge arm unit includes two switches connected in series. The second bridge arm unit includes two switches connected in series. An inductor is connected between the midpoint of the first bridge arm unit and the midpoint of the second bridge arm unit to form an H-bridge conversion circuit. The controller 320 is also configured to determine the bridge arm unit for power conversion from the first bridge arm unit and the second bridge arm unit according to the operating mode of the voltage conversion circuit 310.

[0125] The voltage conversion circuit 310 operates in four modes: boost charging, boost discharging, buck charging, and buck discharging. The operating mode of the voltage conversion circuit 310 is determined based on a working command, its input voltage, and its actual output voltage. The working command can include charging commands, discharging commands, etc., and can be sent from a monitoring host computer to the controller via communication. When the working command is a charging command, if the input voltage of the voltage conversion circuit 310 is greater than the actual output voltage, the operating mode is determined to be buck charging; otherwise, the operating mode is determined to be boost charging. Similarly, when the working command is a discharging command, if the input voltage of the voltage conversion circuit 310 is greater than the actual output voltage, the operating mode is determined to be buck discharging; otherwise, the operating mode is determined to be boost discharging.

[0126] For example, the bidirectional buck-boost circuit 310 is as follows: Figure 3 As shown. The first bridge arm unit includes two switches Q1 and Q2 connected in series, and the second bridge arm unit includes two switches Q3 and Q4 connected in series. Inductor L2 is connected between the midpoint of the first bridge arm unit and the midpoint of the second bridge arm unit to form an H-bridge converter circuit. The H-bridge converter circuit can be a boost circuit or a buck circuit, for example, forming a boost circuit or a buck circuit.

[0127] For example, when the bidirectional buck-boost circuit 310 operates in buck charging mode, the controller 320 can determine Figure 3In the bidirectional buck-boost circuit 310, the first bridge arm unit serves as the bridge arm unit for power conversion. Switch Q1 is the main switch, Q2 is the freewheeling switch, Q3 remains on, and Q4 remains off. When the bidirectional buck-boost circuit 310 operates in boost charging mode, the controller 320 can determine the second bridge arm unit as the bridge arm unit for power conversion, with switch Q4 as the main switch, Q3 as the freewheeling switch, Q1 remaining on, and Q2 remaining off. When the bidirectional buck-boost circuit 310 operates in buck discharging mode, the controller 320 can determine the second bridge arm unit as the bridge arm unit for power conversion, with switch Q3 as the main switch, Q4 as the freewheeling switch, Q1 remaining on, and Q2 remaining off. When the bidirectional buck-boost circuit 310 operates in boost discharge mode, the controller 320 can determine the first bridge arm unit as the bridge arm unit used for power conversion, with switch Q2 as the main switch, switch Q1 as the freewheeling switch, switch Q3 remaining on, and switch Q4 remaining off.

[0128] Those skilled in the art will understand that Figure 8 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the voltage conversion device 300 to which the present application is applied. The specific voltage conversion device 300 may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0129] It should be understood that the controller 320 may include a central processing unit (CPU), and may also include other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0130] It should be noted that those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process of the voltage conversion device 300 described above can be referred to the corresponding process in the control method embodiment of the aforementioned voltage conversion circuit, and will not be repeated here.

[0131] Please see Figure 9 , Figure 9This is a schematic block diagram of the structure of an electronic device provided in an embodiment of this application.

[0132] like Figure 9 As shown, the electronic device 400 includes a voltage conversion device 410. This voltage conversion device 410 can be the voltage conversion device 300 described in the preceding embodiments.

[0133] The electronic device 400 may be, for example, an energy storage device, which includes a battery module and one or more energy storage units, such as one or more batteries. Exemplarily, the electronic device may also be a household air conditioner, outdoor air conditioner, washing machine, water heater, lawnmower, or other electrical appliance.

[0134] In one embodiment, the electronic device 400 may further include multiple circuit units, such as inverter circuits, rectifier circuits, voltage regulator circuits, etc. The circuit units in the electronic device 400 can be directly or indirectly connected to the voltage conversion circuit in the voltage conversion device 410.

[0135] This application also provides a computer-readable storage medium storing one or more computer programs. The one or more computer programs include program instructions, which can be executed by one or more processors. The method implemented when the program instructions are executed can refer to various embodiments of the control method of the voltage conversion circuit of this application.

[0136] The computer-readable storage medium can be an internal storage unit of the voltage conversion device or electronic device described in the foregoing embodiments, such as a hard disk or memory of the voltage conversion device or electronic device. The computer-readable storage medium can also be an external storage device of the voltage conversion device or electronic device, such as a plug-in hard disk, smart media card (SMC), secure digital card (SD), flash card, etc., equipped on the voltage conversion device or electronic device.

[0137] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0138] It should also be understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. It should be noted that, herein, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0139] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. The above descriptions are merely specific implementations of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A control method for a voltage conversion circuit, the voltage conversion circuit comprising an inductor for energy storage and a bridge arm unit for power conversion; the bridge arm unit comprising two switching transistors connected in series; The first end of the inductor is connected between two switching transistors, and the method includes: Obtain the actual output voltage of the voltage conversion circuit; The reference current of the voltage conversion circuit is determined based on the actual output voltage of the voltage conversion circuit and the load operating voltage. The operating condition of the voltage conversion circuit is determined based on the reference current; When the voltage conversion circuit is operating under light load, the first voltage difference across the inductor and the inductance value are obtained. The first duty cycle is determined based on the reference current, the first voltage difference, and the inductance value. A first drive signal is generated based on the first duty cycle, and a first turn-off signal is output; the first drive signal is used to control the on / off state of the main switch in the bridge arm unit, and the first turn-off signal is used to control the freewheeling switch in the bridge arm unit to remain off. Determining the operating conditions of the voltage conversion circuit based on the reference current includes: If the reference current is less than or equal to the preset current value, the operating condition of the voltage conversion circuit is determined to be light load; the preset current value is the critical current value for the inductor to switch from continuous current mode to discontinuous current mode. If the reference current is greater than the preset current value, then the voltage conversion circuit is determined to be operating under heavy load.

2. The control method according to claim 1, wherein, Determining the reference current of the voltage conversion circuit based on the actual output voltage and load operating voltage includes: Calculate the difference between the actual output voltage and the load operating voltage to obtain the second voltage difference; The reference current is determined based on the second voltage difference and the first deviation adjustment algorithm.

3. The control method according to claim 1, wherein, Determining the first duty cycle based on the reference current, the first voltage difference, and the inductance value includes: Obtain the switching cycle of the main switch transistor; Determine a first ratio between the inductance value and the first voltage difference; Calculate the product of the reference current and the first ratio; The first duty cycle is determined based on the ratio between the product value and the switching cycle.

4. The control method according to claim 3, wherein, Obtaining the first voltage difference across the inductor includes: Obtain the input voltage of the voltage conversion circuit; The voltage difference between the input voltage and the actual output voltage is calculated to obtain the first voltage difference.

5. The control method according to any one of claims 1-4, wherein, The control method further includes: When the voltage conversion circuit is under heavy load, the actual output current of the voltage conversion circuit is obtained; The difference between the reference current and the actual output current is determined to obtain the current difference. The target voltage value is determined based on the current difference and the second deviation adjustment algorithm. The second duty cycle is determined based on the ratio between the target voltage value and the input voltage of the voltage conversion circuit; A second drive signal and a third drive signal are generated according to the second duty cycle; the second drive signal is used to drive the main switch of the bridge arm unit to turn on and off, and the third drive signal is used to drive the freewheeling switch of the bridge arm unit to turn on and off, so as to control the two switches in the bridge arm unit to conduct complementaryly.

6. A voltage conversion device, the voltage conversion device comprising a voltage conversion circuit and a controller; The controller is connected to the controlled terminals of each switching transistor in the voltage conversion circuit, and the controller is configured to implement the control method of claim 1.

7. The voltage conversion device as described in claim 6, wherein, The voltage conversion circuit is a half-bridge buck converter.

8. The voltage conversion device as described in claim 7, wherein, The voltage conversion circuit is a bidirectional buck-boost circuit, which includes a first bridge arm unit and a second bridge arm unit. The first bridge arm unit includes two switching transistors connected in series; The second bridge arm unit includes two switching transistors connected in series; The inductor is connected between the midpoint of the first bridge arm unit and the midpoint of the second bridge arm unit to form an H-bridge converter circuit. The controller is also configured to determine, from the first bridge arm unit and the second bridge arm unit, the bridge arm unit for power conversion based on the operating mode of the voltage conversion circuit.

9. An electronic device comprising a voltage conversion device as described in any one of claims 6-8.

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