Control method of voltage conversion circuit, voltage conversion device, and storage medium

Abstract

The embodiment of the application provides a control method of a voltage conversion circuit, a voltage conversion device and a storage medium, the method comprising: at the starting moment of a current PWM period, updating the reference duty cycle of a PWM generator according to a wave trough duty cycle; determining a wave peak duty cycle according to the wave trough sampling result, the historical wave peak sampling result and the historical midpoint voltage of the voltage conversion circuit; at the carrier wave peak moment of the current PWM period, updating the reference duty cycle of the PWM generator according to the wave peak duty cycle, so as to update the driving signal of the first bridge arm. The driving signal can be updated twice in one PWM period, and the control delay is reduced.

Description

Technical Field

[0001] This application relates to the field of electronic power conversion technology, and in particular to a control method, voltage conversion device, and storage medium for a voltage conversion circuit. Background Technology

[0002] Voltage conversion circuits typically include a bridge arm formed by two series-connected switches, which controls the circuit's output voltage. In related technologies, this bridge arm can be driven by deviation control such as proportional-integral (PI) or proportional-integral-derivative (PID) regulation, combined with pulse width modulation (PWM), to achieve the desired output voltage. However, the entire control process based on PI regulation is complex. From sampling to calculating the deviation value, to determining the control parameters of the PWM controller based on the deviation value, and then the PWM controller outputting a modulated PWM wave to drive the voltage conversion circuit, the control parameters finally take effect, resulting in a significant control delay. A large control delay can lead to voltage control failure to converge. Related technologies can reduce control delay by increasing the control frequency. However, increasing the control frequency shortens the single-cycle time, while the computational task of PI control remains unchanged, requiring a higher processor computational power. Therefore, when the processor's computational power is limited or the computational workload of PI control is large, increasing the control frequency cannot reduce the control delay. Summary of the Invention

[0003] This application provides a control method, a voltage conversion device, and a storage medium for a voltage conversion circuit, which can reduce the control delay of the voltage conversion circuit.

[0004] In a first aspect, this application provides a control method for a voltage conversion circuit, the voltage conversion circuit including a first bridge arm, the first bridge arm being formed by two switching transistors connected in series, the method including: At the beginning of the current PWM cycle, the reference duty cycle of the PWM generator is updated according to the trough duty cycle; wherein, the PWM generator is used to output a drive signal to drive the first bridge arm according to the reference duty cycle; the trough duty cycle is the result of deviation adjustment of the voltage conversion circuit in the previous PWM cycle; The peak duty cycle is determined based on the trough sampling results, historical peak sampling results, and historical midpoint voltage of the voltage conversion circuit. The trough sampling results include the first input voltage and first output voltage of the voltage conversion circuit sampled at the start of the current PWM cycle. The historical peak sampling results include the second output voltage of the voltage conversion circuit sampled at the carrier peak of the previous PWM cycle. The historical midpoint voltage is a first reference value of the midpoint voltage determined after deviation adjustment of the voltage conversion circuit in the previous PWM cycle, and the midpoint voltage is the series connection voltage of the two switching transistors. At the peak of the carrier wave in the current PWM cycle, the reference duty cycle of the PWM generator is updated according to the peak duty cycle to update the drive signal of the first bridge arm.

[0005] Secondly, this application provides a voltage conversion device, which includes 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 aforementioned control method.

[0006] Thirdly, this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, causes the processor to implement the steps of the control method for the voltage conversion circuit described above.

[0007] This application discloses a control method, voltage conversion device, and storage medium for a voltage conversion circuit. By sampling twice—at the beginning of each PWM cycle and at the carrier peak—two duty cycles are determined based on two control algorithms and the sampling results. The peak duty cycle is obtained before the carrier peak of the current PWM cycle and is used at the carrier peak to update the reference duty cycle of the PWM generator to adjust the drive signal of the first bridge arm of the voltage conversion circuit. The trough duty cycle is used at the beginning of the next PWM cycle to update the reference duty cycle of the PWM generator to adjust the drive signal of the first bridge arm. By adding an additional sampling at the carrier peak and performing simple calculations based on the sampling results, two updates of the drive signal within one PWM cycle can be achieved, reducing control delay. Attached Figure Description

[0008] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the 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.

[0009] Figure 1 This is a flowchart illustrating the control method of the voltage conversion circuit according to an embodiment of this application; Figure 2 A schematic block diagram of a voltage conversion device provided in an embodiment of this application; Figure 3 This is a circuit diagram of the voltage conversion circuit in Embodiment 1 of this application; Figure 4 This is a timing diagram of the control method in the first embodiment of this application; Figure 5 This is a schematic diagram of deviation adjustment in the first embodiment of this application; Figure 6 This is a timing diagram illustrating the control of a voltage conversion circuit based on the trough duty cycle. Detailed Implementation

[0010] 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.

[0011] 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.

[0012] This application provides a control method for a voltage conversion circuit. By sampling twice—at the beginning of each PWM cycle and at the carrier peak—two duty cycles are determined based on two control algorithms and the sampling results. The peak duty cycle is obtained before the carrier peak of the current PWM cycle and is used at the carrier peak to update the reference duty cycle of the PWM generator to adjust the drive signal of the first bridge arm of the voltage conversion circuit. The trough duty cycle is used at the beginning of the next PWM cycle to update the reference duty cycle of the PWM generator to adjust the drive signal of the first bridge arm. By adding an additional sampling at the carrier peak and performing simple calculations based on the sampling results, two updates of the drive signal within one PWM cycle can be achieved, reducing control delay.

[0013] 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.

[0014] Please see Figure 1 , Figure 1This is a schematic flowchart illustrating a control method for a voltage conversion circuit provided in an embodiment of this application.

[0015] The control method for the voltage conversion circuit provided in this application embodiment can be applied to a controller, which is configured to implement the control method of this application embodiment.

[0016] Specifically, the controller is connected to the voltage conversion circuit. For example, the controller is connected to the controlled terminal of each switch in the voltage conversion circuit to send PWM waves to each switch, driving each switch and enabling the voltage conversion circuit to perform voltage conversion.

[0017] Please see Figure 2 , Figure 2 This is a schematic block diagram of a voltage conversion device 10 provided in an embodiment of this application. The voltage conversion device 10 includes a voltage conversion circuit 100 and a controller 200. The controller 200 is connected to the controlled terminals of each switching transistor in the voltage conversion circuit 100, and the controller 200 is configured to implement the control method of the embodiment of this application.

[0018] Specifically, such as Figure 3 As shown, the voltage conversion circuit 100 includes a first bridge arm 110, which is formed by two switching transistors connected in series. Optionally, the two switching transistors connected in series in the first bridge arm 110 can be referred to as the upper transistor Q1 and the lower transistor Q2, respectively, and the upper transistor Q1 and the lower transistor Q2 are complementary in conduction. Accordingly, the drive signal of the first bridge arm 110 can include two complementary PWM waves to control the complementary conduction of the upper transistor Q1 and the lower transistor Q2, that is, when the upper transistor Q1 is on, the lower transistor Q2 is off, and when the upper transistor Q1 is off, the lower transistor Q2 is on. For ease of explanation, the embodiments of this application mainly use the PWM wave of the upper transistor Q1 as an example for illustration. Exemplarily, the voltage conversion circuit 100 can include a single-phase or three-phase half-bridge circuit or a full-bridge circuit. For example, when the voltage conversion circuit only includes the first bridge arm 110, it is a half-bridge circuit. When the voltage conversion circuit is a full-bridge circuit including two bridge arms, the first bridge arm is the bridge arm used for power conversion, that is, the bridge arm used to control the output voltage.

[0019] It can be understood that the upper transistor Q1 is connected in parallel with the freewheeling diode D1, and the lower transistor Q2 is connected in parallel with the freewheeling diode D2. In some embodiments, the freewheeling diode may also be part of the switching transistor, for example, it may be the body diode within the switching transistor.

[0020] For example, the switching transistors may include giant transistors (GTRs), metal-oxide-semiconductor field-effect transistors (MOSFETs), or insulated-gate bipolar transistors (IGBTs), etc., and each of the aforementioned GTRs, MOSFETs, and IGBTs includes a body diode. In other embodiments, the upper transistor Q1 and the lower transistor Q2 may also be formed by a transistor and a diode connected in parallel, and this application does not impose any limitations on this.

[0021] The input side of the first bridge arm 110 is connected to a first capacitor C1, which is used to stabilize the input voltage of the first bridge arm 110, for example, referred to as V1. For instance, the first capacitor C1 is also connected to a power supply, which stabilizes the voltage supplied by the power supply to the first bridge arm 110. The output side of the first bridge arm 110 is connected to a load R1, and the output voltage supplied by the first bridge arm 110 to the load R1 is, for example, referred to as V2. Optionally, a second capacitor C2 is connected to the output side of the first bridge arm 110, which is used to filter out noise in the output voltage.

[0022] By adjusting the duty cycle of the drive signal of the first bridge arm 110, the conduction duration of the upper transistor Q1 and the lower transistor Q2 in each control cycle (or the switching cycle of the upper transistor Q1 and the lower transistor Q2) in the first bridge arm 110 can be adjusted. This allows the output voltage V2 of the first bridge arm 110 to converge to the reference voltage and / or the output current of the first bridge arm 110 to converge to the reference current, thereby providing the required voltage and / or current to the load R1 and ensuring the stable and reliable operation of the load R1.

[0023] For example, the driving signal of the first bridge arm 110 is a PWM (Pulse-Width Modulation) wave, and the control period of the switching transistor in the first bridge arm 110 is consistent with the PWM period of the driving signal driving the first bridge arm 110.

[0024] Optionally, the first bridge arm 110 outputs voltage through the series connection point of the two switching transistors, i.e., the midpoint of the first bridge arm 110. The voltage at the series connection point of the two switching transistors can be called the series connection point voltage or the midpoint voltage of the first bridge arm 110.

[0025] In some embodiments, the voltage conversion circuit 100 further includes an energy storage inductor L1 connected to the midpoint of the first bridge arm 110, with one end of the energy storage inductor L1 connected to the midpoint of the first bridge arm 110 and the other end of the energy storage inductor L1 connected to the load R1 and the second capacitor C2.

[0026] like Figure 1 As shown, the control method for the voltage conversion circuit includes the following steps S110 to S130.

[0027] Step S110: At the beginning of the current PWM cycle, update the reference duty cycle of the PWM generator according to the trough duty cycle; wherein, the PWM generator is used to output a drive signal to drive the first bridge arm according to the reference duty cycle; the trough duty cycle is the result of the deviation adjustment of the voltage conversion circuit in the previous PWM cycle.

[0028] For ease of explanation, such as Figure 4 As shown, the current PWM period can be called period k, the previous PWM period can be called period (k-1), and the next PWM period can be called period (k+1). At the beginning time e of the current PWM period, the trough duty cycle is obtained by adjusting the deviation of the voltage conversion circuit according to the previous PWM period. Update the reference duty cycle of the PWM generator. Correspondingly, at the beginning time a of period (k-1), the trough duty cycle obtained from period (k-2) can be used. Update the reference duty cycle of the PWM generator; alternatively, at the beginning of the next PWM cycle, i.e., at time i of cycle (k+1), adjust the trough duty cycle based on the current PWM cycle, i.e., cycle k. Update the reference duty cycle of the PWM generator. That is, the duty cycle calculated by the deviation adjustment for each PWM cycle will be updated to the PWM generator at the beginning of the next PWM cycle, i.e., at the trough time.

[0029] Step S120: Determine the peak duty cycle based on the trough sampling results, historical peak sampling results, and historical midpoint voltage of the voltage conversion circuit; wherein, the trough sampling results include the first input voltage and the first output voltage of the voltage conversion circuit sampled at the beginning of the current PWM cycle; the historical peak sampling results include the second output voltage of the voltage conversion circuit sampled at the carrier peak moment of the previous PWM cycle; the historical midpoint voltage is the first reference value of the midpoint voltage determined after deviation adjustment of the voltage conversion circuit in the previous PWM cycle, and the midpoint voltage is the series connection point voltage of the two switching transistors.

[0030] Please see Figure 4 The input and output voltages of the voltage conversion circuit can be sampled at the beginning of each PWM cycle to obtain the first input voltage and the first output voltage. The first input voltage and the first output voltage sampled at the beginning of the PWM cycle can be called the trough sampling result. For example, the trough sampling result of the previous PWM cycle, i.e., cycle (k-1), includes the first input voltage. and first output voltage The current PWM period, i.e., the trough sampling result of period k, includes the first input voltage. and first output voltage .

[0031] The second output voltage of the voltage conversion circuit can also be sampled at the carrier peak time of each PWM cycle, for example, the second output voltage can be obtained at the carrier peak time c of period (k-1). The second output voltage is obtained at the peak of the carrier wave during period k. .

[0032] For example, in period (k-1), deviation adjustment is performed based on a preset deviation adjustment algorithm and the trough sampling results to determine the trough duty cycle of period k. At this time, the first reference value of the midpoint voltage of the period (k-1) can be obtained. At the beginning of period k, e is based on When updating the reference duty cycle of the PWM generator, the midpoint voltage of the first bridge arm can be made to approach the first reference value. .

[0033] Step S130: At the peak of the carrier wave in the current PWM cycle, update the reference duty cycle of the PWM generator according to the peak duty cycle to update the drive signal of the first bridge arm.

[0034] For example, such as Figure 4 As shown, at the peak time g of the carrier wave with period k, according to the peak duty cycle... Update the reference duty cycle of the PWM generator.

[0035] At the end of period k, at the beginning of period (k+1) time i, the duty cycle of the trough determined in period k can be used as a reference. The reference duty cycle of the PWM generator is updated; in this embodiment, the reference duty cycle can be updated before the start time i of period (k+1) based on the peak duty cycle determined in period k. Update the reference duty cycle of the PWM generator, the peak duty cycle. Compared to trough duty cycle It can more accurately reflect the current state of the PWM periodic voltage conversion circuit, and can compare the trough duty cycle. Earlier activation allows for two updates to the drive signal within a single PWM cycle, reducing control latency.

[0036] The control method for the voltage conversion circuit provided in this application performs two samplings at the beginning and peak of each PWM cycle. Based on two control algorithms and the results of the two samplings, two duty cycles are determined. The peak duty cycle is obtained before the peak of the current PWM cycle and is used at the peak of the carrier wave to update the reference duty cycle of the PWM generator to adjust the drive signal of the first bridge arm of the voltage conversion circuit. The trough duty cycle is used at the beginning of the next PWM cycle to update the reference duty cycle of the PWM generator to adjust the drive signal of the first bridge arm. By adding an additional sampling at the peak of the carrier wave and performing simple calculations based on the sampling results, the drive signal can be updated twice within one PWM cycle, reducing control delay.

[0037] Optionally, embodiments of this application can reduce control delay without altering the PWM cycle.

[0038] Optionally, embodiments of this application can also avoid the problem that the controller's limited capabilities prevent it from increasing the control frequency, resulting in excessively long control delays, affecting the control results, and causing unstable output voltage.

[0039] In some implementations, the method further includes step S101: adjusting the deviation according to a preset deviation adjustment algorithm and the trough sampling results to determine the trough duty cycle of the next PWM cycle.

[0040] Please refer to Figure 4 The trough duty cycle for the next PWM cycle is determined after the carrier peak time of the current PWM cycle. For example, the trough duty cycle for cycle (k+1). The time h following the carrier peak time g of period k is determined, and correspondingly, the trough duty cycle of period k is determined. The time d is determined after the carrier peak time c of period (k-1). Specifically, it is determined after the carrier peak time of the current PWM period and before the start time of the next PWM period, so that the reference duty cycle of the PWM generator is updated according to the determined trough duty cycle at the start time of the next PWM period.

[0041] For example, in the previous PWM cycle of the current PWM cycle, the deviation adjustment algorithm is used as the basis for the adjustment, and the first input voltage of the previous PWM cycle is used as the basis for the adjustment. and first output voltage Deviation adjustment can be performed to determine the trough duty cycle of the current PWM period. Similarly, in the current PWM cycle, the deviation can be adjusted according to a preset deviation algorithm and the first input voltage of the current PWM cycle. and first output voltage Adjust the deviation to determine the trough duty cycle for the next PWM cycle. .

[0042] For example, based on a preset deviation adjustment algorithm (such as a PI algorithm), according to the reference voltage (such as a voltage setpoint) and the first output voltage... Determine the voltage deviation value, and then compare it with the first input voltage. Determine the trough duty cycle for the next PWM cycle Of course, it is not limited to this.

[0043] In some implementations, please refer to Figure 3 The voltage conversion circuit 100 also includes an energy storage inductor L1 connected to the midpoint of the first bridge arm 110. The trough sampling result of the current PWM cycle also includes the first inductor current of the energy storage inductor L1 sampled at the beginning of the current PWM cycle. First inductor current This can be referred to as the feedback current of the voltage conversion circuit 100. For example, the first inductor current sampled at the beginning of the current PWM cycle can be expressed as... .

[0044] For example, when adjusting the deviation based on the preset deviation adjustment algorithm and the trough sampling results to determine the trough duty cycle of the next PWM cycle, the preset deviation adjustment algorithm and the first input voltage of the current PWM cycle can be used. First output voltage and the first inductor current Adjust the deviation to determine the trough duty cycle for the next PWM cycle. .

[0045] For example, the method also includes steps S1011 to S1014. That is, steps S1011 to S1014 can also be used to adjust the deviation according to a preset deviation adjustment algorithm and the trough sampling result to determine the trough duty cycle of the next PWM cycle.

[0046] Step S1011: Based on the reference current (For example, given a current value) and the first inductor current Determine the current deviation value.

[0047] Please see Figure 5 The controller 200 includes a PWM generator 201, a first subtractor 202, a PI control module 203, and a second subtractor 204, forming a current control loop. The trough duty cycle of period (k+1) is determined based on the current PWM cycle, i.e., period k. For example, the inductor current in the first cycle of the current PWM period The feedback current of the current control loop is input to the first subtractor 201, and the first subtractor 201 adjusts the current according to the reference current. With the first inductor current Determine the current deviation value.

[0048] Step S1012: Calculate the deviation based on the preset deviation adjustment algorithm and the current deviation value to obtain the second voltage deviation value.

[0049] The PI control module 202 calculates the deviation of the current deviation value based on a preset deviation adjustment algorithm to obtain the second voltage deviation value.

[0050] Step S1013: Measure the first output voltage. The first reference value Vpwm of the midpoint voltage of the current PWM cycle is obtained by summing the second voltage deviation value.

[0051] The first input voltage of the current PWM cycle As the feedforward voltage input to the current control loop, the second subtractor 203 is based on the first output voltage. The first reference value for calculating the midpoint voltage of the current PWM cycle is the second voltage deviation value. .

[0052] Step S1014: Based on the first reference value Vpwm of the midpoint voltage and the first input voltage The ratio of the two values ​​determines the trough duty cycle of the next PWM cycle. .

[0053] First reference value This can be used as the desired voltage at the midpoint of the first bridge arm before the carrier peak of the next PWM cycle; for example, at the beginning of cycle (k+1), e is based on... When updating the reference duty cycle of the PWM generator, the midpoint voltage of the first bridge arm can be made to approach or reach the first reference value. .

[0054] The controller 200 can also base its operation on a first reference value of the midpoint voltage of the current PWM cycle. and the first input voltage The ratio of the two values ​​determines the trough duty cycle of the next PWM cycle. ÷ ; and at the beginning of the next PWM cycle, based on the trough duty cycle Update the reference duty cycle of PWM generator 201 so that PWM generator 201 outputs drive signals according to the reference duty cycle to drive the upper and lower transistors in the first bridge arm.

[0055] In step S110, at the beginning of the current PWM cycle, the value of the comparison register of the PWM generator is updated according to the trough duty cycle, thereby controlling the PWM generator to output the drive signal corresponding to the trough duty cycle to drive the first bridge arm.

[0056] In some implementations, updating the reference duty cycle of the PWM generator according to the trough duty cycle in step S110 includes steps S111 to S113.

[0057] Step S111: Update the reference duty cycle of the PWM generator to the trough duty cycle.

[0058] For example, in the previous PWM cycle, the trough duty cycle is determined according to step S101 or steps S1011 to S1014, and at the beginning of the current PWM cycle, the reference duty cycle of the PWM generator is updated to the trough duty cycle.

[0059] Step S112: Calculate the first comparison value based on the counting threshold of the PWM generator and the updated reference duty cycle.

[0060] For example, when the PWM generator outputs a high level when the count value is greater than or equal to the comparison value, the first comparison value can be duty × A, where duty represents the updated reference duty cycle and A represents the count threshold of the PWM generator.

[0061] Step S113: Update the value of the comparison value register of the PWM generator according to the first comparison value.

[0062] Optionally, the PWM generator includes a counter, which can output a low or high level (i.e., 0 or 1) based on the comparison result between the counter's count value and the comparison value. For example, in each PWM cycle, as the counter counts, the PWM generator outputs a high level when the counter's count value is less than the comparison value, and outputs a low level when the counter's count value is greater than or equal to the comparison value; thus, the PWM generator can output a PWM wave as the drive signal for the first bridge arm.

[0063] The duty cycle of a PWM wave can be determined by a comparison value. For example, by adjusting the comparison value of the PWM generator, the duration of the high-level output of the PWM generator within the PWM cycle can be adjusted, thereby adjusting the duty cycle of the PWM wave, i.e., the drive signal. For instance, the PWM generator also includes a comparison value register, which stores the comparison value of the PWM generator. That is, by adjusting the value of the comparison value register, the duty cycle of the drive signal output by the PWM generator can be adjusted.

[0064] In some implementations, step S120 determines the peak duty cycle based on the trough sampling results of the voltage conversion circuit, the historical peak sampling results, and the historical midpoint voltage, including steps S121 to S122.

[0065] Step S121: Calculate the first voltage deviation value between the first output voltage and the second output voltage.

[0066] First voltage deviation value, for example It can characterize the changes in the output voltage of the voltage conversion circuit. Using this first voltage deviation value, the peak duty cycle can be determined relatively quickly, and the determined peak duty cycle can accurately track the changes in the output voltage of the voltage conversion circuit, so as to accurately and timely control the voltage conversion circuit.

[0067] Step S122: Calculate the peak duty cycle based on the first voltage deviation value, the historical midpoint voltage, and the first input voltage.

[0068] The peak duty cycle is determined by calculating the peak duty cycle based on the first voltage deviation value, the historical midpoint voltage, and the first input voltage. Compared with the deviation adjustment algorithm, the peak duty cycle can be determined more quickly and with higher calculation accuracy.

[0069] For example, step S122 calculates the peak duty cycle based on the first voltage deviation value, the historical midpoint voltage, and the first input voltage, including steps S1221 to S1222.

[0070] Step S1221: Determine the second reference value of the midpoint voltage of the current PWM cycle based on the sum of the first voltage deviation value and the historical midpoint voltage.

[0071] For example, the second reference value of the midpoint voltage of period k. Historical midpoint voltage, such as This is the expected value of the midpoint voltage determined after deviation adjustment over period (k-1), i.e., the first reference value of the midpoint voltage. The second reference value of the midpoint voltage for the current PWM period is determined by summing the first voltage deviation value and the historical midpoint voltage over period k. This allows for updating the expected value of the midpoint voltage based on the first voltage deviation value, thereby reducing control delay and improving control accuracy.

[0072] Step S1222: Determine the peak duty cycle based on the ratio of the second reference value of the midpoint voltage to the first input voltage.

[0073] For example, the controller can also base its actions on a second reference value of the midpoint voltage of the current PWM cycle. and the first input voltage The ratio of the peak duty cycle to the peak duty cycle of the current PWM period is used to determine the peak duty cycle. When based on the peak duty cycle When controlling the first bridge arm, the midpoint voltage of the first bridge arm can be made to approach the second reference value. .

[0074] Based on a control algorithm that differs from the preset deviation adjustment algorithm, the peak duty cycle can be determined before the carrier peak time of the current PWM cycle. And at the peak of the carrier wave in the current PWM cycle, based on the peak duty cycle... Updating the reference duty cycle of the PWM generator allows for two updates to the drive signal within one PWM cycle, reducing control latency.

[0075] Specifically, the control algorithm used to determine the peak duty cycle can determine the calculation result of the peak duty cycle more quickly than the deviation adjustment algorithm, so that the drive signal of the first bridge arm can be updated according to the peak duty cycle in the current PWM cycle.

[0076] In some implementations, when updating the reference duty cycle of the PWM generator based on the peak duty cycle to update the drive signal of the first bridge arm in step S130, a second comparison value can be calculated based on the PWM generator's counting threshold and the updated reference duty cycle; the value of the PWM generator's comparison value register is then updated based on the second comparison value. For example, when the PWM generator outputs a high level when the count value is greater than or equal to the comparison value, the second comparison value can be duty × A, where duty represents the updated reference duty cycle and A represents the PWM generator's counting threshold.

[0077] In some implementations, the PWM generator operates in a center-aligned mode. See also... Figure 4 In each PWM cycle, the counter of the PWM generator first counts upwards. When the count value reaches the counting threshold, the counter starts counting downwards, thus obtaining the waveform of the triangular carrier wave of the PWM generator. Optionally, the counter starts counting upwards from the lower limit value to the counting threshold, and ends the current PWM cycle when counting downwards from the counting threshold to the lower limit, and restarts counting upwards from the lower limit value when entering the next PWM cycle. For ease of explanation, the embodiments of this application mainly use a lower limit value of 0 as an example for illustration.

[0078] For example, the counting threshold of the counter can be determined based on the duration T of the PWM cycle. For instance, the time it takes for the counter to count from the lower limit to the counting threshold is equal to half the duration T of the PWM cycle.

[0079] Optionally, the moment when the counter counts to the lower limit can be called the carrier trough moment of the PWM cycle. For example, the start moment e of the current PWM cycle is the carrier trough moment of the current PWM cycle. When the counter counts to the count threshold moment, it can be called the carrier peak moment of the PWM cycle, such as the carrier peak moment c of period (k-1), the carrier peak moment g of period k, and the carrier peak moment l of period (k+1).

[0080] For example, the trough duty cycle is obtained by adjusting the deviation at the beginning time e of the current PWM cycle, which is the trough time of the carrier wave in the current PWM cycle. Update the reference duty cycle of the PWM generator so that the PWM generator outputs the duty cycle of that trough. The corresponding drive signal enables deviation control of the voltage conversion circuit.

[0081] Please combine Figure 5 See Figure 6 In related technologies, due to the complexity of deviation adjustment algorithms, such as the PI algorithm, which requires a certain amount of time for calculation, and the fact that, according to the PWM wave generation mechanism, the comparison value corresponding to the trough duty cycle of the current PWM cycle will be delayed by one cycle before being updated to the comparison value register of the PWM generator 201, and there is also a certain delay between the update of the comparison value register and the generation of the PWM wave corresponding to the trough duty cycle by the PWM generator 201, the overall control delay of the deviation adjustment algorithm is lengthened. This control delay is... Figure 5 This is represented by e^(-1.5sT), which means that the sampling result of the trough of e at the beginning of the current PWM cycle will take effect only after a delay of this duration.

[0082] by Figure 6 For example, at the beginning of period (k-1), current and voltage are sampled to obtain the trough sampling results of period (k-1); at the beginning of period (k-1), a is also based on the trough duty cycle. Update the reference duty cycle of the PWM generator, for example, by updating the value of the compare register. Within period (k-1), adjust the deviation according to the preset deviation adjustment algorithm and the trough sampling results of period (k-1), and determine the first reference value of the midpoint voltage of period k before the start time e of period k. Duty cycle of troughs At the beginning of period k, current and voltage are sampled at time e to obtain the trough sampling results of period k; at the beginning of period k, e also considers the trough duty cycle. Update the reference duty cycle of the PWM generator, for example, by updating the value of the compare register. Within period k, adjust the deviation according to the preset deviation adjustment algorithm and the trough sampling results of period k. Determine the first reference value of the midpoint voltage of period k before the start time i of period (k+1). Duty cycle of troughs It is understandable that, ideally, the duty cycle at the trough of a given period k is... At least during period (k+1), when the count value of the PWM generator reaches the counting threshold, i.e., when the carrier wave peaks, the trough duty cycle must be... Only the corresponding drive signal can take effect, and the output trough duty cycle will be adjusted. The corresponding PWM wave acts on the upper and lower transistors in the first bridge arm. Thus, the current and voltage values ​​sampled at point e in period k will only take effect at least at the carrier wave peak of period (k+1), such as point l, with a control delay of more than 1.5×T, where T is the duration of the PWM period.

[0083] The control method for the voltage conversion circuit provided in this application performs two samplings at the beginning and peak of each PWM cycle. Based on two control algorithms and the results of the two samplings, two duty cycles are determined. The peak duty cycle is obtained before the peak of the current PWM cycle and is used at the peak of the carrier wave to update the reference duty cycle of the PWM generator to adjust the drive signal of the first bridge arm of the voltage conversion circuit. The trough duty cycle is used at the beginning of the next PWM cycle to update the reference duty cycle of the PWM generator to adjust the drive signal of the first bridge arm. By adding an additional sampling at the peak of the carrier wave and performing simple calculations based on the sampling results, the drive signal can be updated twice within one PWM cycle, reducing control delay.

[0084] This application also provides a computer-readable storage medium storing a computer program, which includes program instructions. When the computer program is executed by a processor, the processor implements the steps of the control method for the voltage conversion circuit provided in the above embodiments.

[0085] The computer-readable storage medium can be an internal storage unit of the controller or voltage conversion device in any of the foregoing embodiments, such as a hard disk or memory of the voltage conversion device. Alternatively, the computer-readable storage medium can be an external storage device of the controller or voltage conversion device, such as a pluggable hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc., mounted on the controller.

[0086] It should be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application.

[0087] It should also be understood that the term “and / or” as used in this application and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0088] The above description is merely a specific embodiment 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 including a first bridge arm, the first bridge arm being formed by two switching transistors connected in series, characterized in that, The method includes: At the beginning of the current PWM cycle, the reference duty cycle of the PWM generator is updated according to the trough duty cycle; wherein, the PWM generator is used to output a drive signal to drive the first bridge arm according to the reference duty cycle; the trough duty cycle is the result of deviation adjustment of the voltage conversion circuit in the previous PWM cycle; The peak duty cycle is determined based on the trough sampling results, historical peak sampling results, and historical midpoint voltage of the voltage conversion circuit. The trough sampling results include the first input voltage and first output voltage of the voltage conversion circuit sampled at the start of the current PWM cycle. The historical peak sampling results include the second output voltage of the voltage conversion circuit sampled at the carrier peak of the previous PWM cycle. The historical midpoint voltage is a first reference value of the midpoint voltage determined after deviation adjustment of the voltage conversion circuit in the previous PWM cycle, and the midpoint voltage is the series connection voltage of the two switching transistors. At the peak of the carrier wave in the current PWM cycle, the reference duty cycle of the PWM generator is updated according to the peak duty cycle to update the drive signal of the first bridge arm.

2. The control method according to claim 1, characterized in that, The method further includes: The deviation is adjusted according to the preset deviation adjustment algorithm and the trough sampling results to determine the trough duty cycle of the next PWM cycle; wherein the trough duty cycle of the next PWM cycle is determined after the carrier peak time of the current PWM cycle.

3. The control method according to claim 1, characterized in that, The trough sampling result includes a first input voltage and a first output voltage, and the historical peak sampling result includes a second output voltage; The step of determining the peak duty cycle based on the trough sampling results, historical peak sampling results, and historical midpoint voltage of the voltage conversion circuit includes: Calculate the first voltage deviation value between the first output voltage and the second output voltage; The peak duty cycle is calculated based on the first voltage deviation value, the historical midpoint voltage, and the first input voltage.

4. The control method according to claim 3, characterized in that, The step of calculating the peak duty cycle based on the first voltage deviation value, the historical midpoint voltage, and the first input voltage includes: A second reference value for the midpoint voltage of the current PWM cycle is determined based on the sum of the first voltage deviation value and the historical midpoint voltage. The peak duty cycle is determined based on the ratio of the second reference value of the midpoint voltage to the first input voltage.

5. The control method according to claim 3, characterized in that, The voltage conversion circuit also includes an energy storage inductor connected to the midpoint of the first bridge arm, and the trough sampling result also includes the first inductor current of the energy storage inductor sampled at the beginning of the current PWM cycle. The method further includes: The current deviation value is determined based on the reference current and the first inductor current; The second voltage deviation value is obtained by calculating the deviation based on the preset deviation adjustment algorithm and the current deviation value; The first reference value of the midpoint voltage of the current PWM cycle is obtained by summing the first output voltage and the second voltage deviation value; The trough duty cycle of the next PWM cycle is determined based on the ratio of the first reference value of the midpoint voltage to the first input voltage.

6. The control method according to claim 1, characterized in that, The step of updating the reference duty cycle of the PWM generator based on the trough duty cycle includes: Update the reference duty cycle of the PWM generator to the trough duty cycle; The first comparison value is calculated based on the counting threshold of the PWM generator and the updated reference duty cycle; The value of the comparison value register of the PWM generator is updated based on the first comparison value.

7. The control method according to any one of claims 1-6, characterized in that, The PWM generator operates in a center-aligned mode.

8. A voltage conversion device, characterized in that, The voltage conversion device includes 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 according to any one of claims 1-7.

9. The voltage conversion device as described in claim 8, characterized in that, in, The voltage conversion circuit is a half-bridge buck converter.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, causes the processor to implement the steps of the control method for the voltage conversion circuit as described in any one of claims 1 to 7.

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