Control method and controller of power conversion circuit

Abstract

The invention discloses a power conversion circuit control method and a controller thereof. Calculating a first frequency according to an error value; controlling a pulse width modulation module to generate a switching signal according to the first frequency and an intermittent mode setting frequency; generating a cycle count value according to whether the first frequency is higher than the intermittent mode set frequency; according to the period count value and a set period number, whether an instruction signal is transmitted to the pulse width modulation module or not is determined, and the pulse width modulation module sends out the switching signal of one period after receiving the instruction signal.

Description

Technical Field

[0001] This invention relates to a control method for a power conversion circuit and a controller thereof. Background Technology

[0002] LLC resonant power conversion circuits (a type of DC / DC power conversion circuit) have become a hot topic in the field of power electronics because they can meet the demanding performance requirements of modern power supply design.

[0003] This switching mode DC / DC power conversion circuit allows for higher switching frequencies and reduced switching losses, making it more suitable for high-power and high-efficiency applications. LLC resonant power conversion circuits are ideal for power applications with precision systems (i.e., high-end consumer electronics) or higher operating power requirements (i.e., charging electric vehicles).

[0004] Currently, if the LLC resonant cavity (also known as the LLC circuit) of the LLC resonant power conversion circuit is not opened in burst mode and no other measures are taken, the circuit gain is very high under light load, which will result in a very short soft start-up process time for the LLC resonant cavity and a large overcharge current, which will cause the component application to exceed the specifications.

[0005] In the past, the output voltage settling time of LLC circuits was typically between 2ms and 3ms to meet the datasheet requirements (greater than 2ms). However, recently, the industry has demanded that the output voltage settling time of LLC circuits be greater than 5ms, and even greater than 20ms. With current practices, it is not easy to meet these requirements.

[0006] Therefore, this invention proposes a new control method and controller for power conversion circuits in order to meet new industry requirements. Summary of the Invention

[0007] According to a first aspect of the present invention, a power conversion circuit controller is provided, comprising: a switching frequency calculation module for calculating a first frequency based on an error value; a pulse width modulation module; an intermittent mode control module coupled to the switching frequency calculation module and the pulse width modulation module, wherein the intermittent mode control module controls the pulse width modulation module to generate a switching signal based on the first frequency and an intermittent mode set frequency; and a switching cycle counting module coupled to the intermittent mode control module and the pulse width modulation module, wherein the switching cycle counting module generates a cycle count value based on whether the first frequency is higher than the intermittent mode set frequency, and determines whether to transmit a command signal to the pulse width modulation module based on the cycle count value and a predetermined number of cycles, wherein the pulse width modulation module, upon receiving the command signal, issues the switching signal for one cycle.

[0008] According to a second aspect of the present invention, a power conversion circuit control method is provided, comprising: calculating a first frequency based on an error value; controlling a pulse width modulation module to generate a switching signal based on the first frequency and an intermittent mode set frequency; generating a cycle count value based on whether the first frequency is higher than the intermittent mode set frequency; and determining whether to transmit a command signal to the pulse width modulation module based on the cycle count value and a predetermined number of cycles, wherein the pulse width modulation module, upon receiving the command signal, issues the switching signal for one cycle.

[0009] To provide a better understanding of the above and other aspects of the present invention, specific embodiments are described below in conjunction with the accompanying drawings: Attached Figure Description

[0010] Figure 1 This is a functional block diagram of a power conversion circuit according to an embodiment of the present invention;

[0011] Figure 2 This is a functional block diagram of a controller according to an embodiment of the present invention;

[0012] Figure 3 This is a flowchart of a power conversion circuit control method according to an embodiment of the present invention;

[0013] In the attached figures, the following reference numerals are used:

[0014] 100: Power conversion circuit; 105: Controller;

[0015] 110: Power switch; 120: LLC resonant cavity;

[0016] 130: Transformer;

[0017] 140: Diode rectifier;

[0018] 210: Error analog-to-digital converter;

[0019] 220: Switching frequency calculation module;

[0020] 230: Intermittent mode control module;

[0021] 240: Switch cycle counting module;

[0022] 250: Pulse Width Modulation Module;

[0023] 260: Switch cycle count adjustment module;

[0024] f1: First frequency;

[0025] S1: Command signal;

[0026] S31-S34: Steps. Detailed Implementation

[0027] The technical terms used in this specification refer to those commonly used in the field. Where this specification provides explanations or definitions for certain terms, the interpretation of those terms shall be based on the explanations or definitions provided in this specification. Each embodiment of the present invention has one or more technical features. Where feasible, those skilled in the art may selectively implement some or all of the technical features in any embodiment, or selectively combine some or all of the technical features in these embodiments.

[0028] Please refer to Figure 1 This is a functional block diagram of a power conversion circuit according to an embodiment of the present invention. The power conversion circuit 100 according to an embodiment of the present invention includes: a controller 105, a power switch 110, an LLC resonant cavity 120, a transformer 130, and a diode rectifier 140.

[0029] Controller 105 is coupled to power switch 110. Controller 105 (and its internal modules, such as...) Figure 2 (As shown) can be implemented, for example, by using a chip, a circuit block within the chip, a firmware circuit, or a circuit board containing several electronic components and wires, but the present invention is not limited thereto.

[0030] Power switch 110 converts the input DC voltage VIN into a high-frequency square wave. The power switch can be implemented using a full-bridge or half-bridge topology. Controller 105 can generate switching signals (e.g., but not limited to PWM (Pulse Width Modulation)) to control the on or off of the internal switch of power switch 110.

[0031] LLC resonant cavity 120 is coupled to power switch 110. The high-frequency square wave generated by power switch 110 enters LLC resonant cavity 120. LLC resonant cavity 120 eliminates the harmonics of the high-frequency square wave and outputs a fundamental frequency sine wave.

[0032] Transformer 130 is coupled to LLC resonant cavity 120. The fundamental frequency sine wave generated by LLC resonant cavity 120 is transmitted to the two sides of transformer 130 through transformer 130, and the voltage is boosted or stepped down according to the application requirements.

[0033] Diode rectifier 140 is coupled to transformer 130. Diode rectifier 140 converts the sine wave output from transformer 130 into a stable output voltage VOUT. Output voltage VOUT is a DC output voltage. Diode rectifier 140 can be connected to controller 105 to provide output voltage VOUT to controller 105.

[0034] Figure 2This is a functional block diagram of a controller 105 according to an embodiment of the present invention. In one embodiment of the present invention, the controller 105 is, for example, but not limited to, a digital signal processor (DSP). The controller 105 includes: an error analog-to-digital converter (EADC) 210, a switching frequency calculation module 220, an intermittent mode control module 230, a switching cycle counting module 240, a pulse width modulation (PWM) module 250, and a switching cycle counting adjustment module 260.

[0035] The error analog-to-digital converter 210 compares a reference value REF (provided by the ramp module) with the output voltage VOUT to generate an error value for the switching frequency calculation module 220. The reference value REF can be a ramp voltage with a ramp waveform.

[0036] The switching frequency calculation module 220 is coupled to the error analog-to-digital converter 210. The switching frequency calculation module 220 calculates a first frequency f1 based on the error value generated by the error analog-to-digital converter 210. In some embodiments, the switching frequency calculation module 220 may be an error proportional-integral computing module.

[0037] The intermittent mode control module 230 is coupled to the switching frequency calculation module 220 and the pulse width modulation module 250. When the first frequency f1 of the switching frequency calculation module 220 is higher than the intermittent mode set frequency, the intermittent mode control module 230 controls the pulse width modulation module 250 to keep its switching signal constantly low. When the first frequency f1 of the switching frequency calculation module 220 is lower than the intermittent mode set frequency, the intermittent mode control module 230 controls the pulse width modulation module 250 to output a normal switching signal. When the switching signal of the pulse width modulation module 250 is constantly low, the internal switch of the power switch 110 does not switch. When the switching signal of the pulse width modulation module 250 has a switching waveform, the internal switch of the power switch 110 switches.

[0038] The switching cycle counting module 240 is coupled to the intermittent mode control module 230. If, within a complete cycle, the first frequency f1 of the switching frequency calculation module 220 is higher than the intermittent mode set frequency (i.e., the switching signal of the pulse width modulation module 250 is always logic low), then the switching cycle counting module 240 adds a predetermined cycle count value (e.g., but not limited to 1). That is, for example, if, within three consecutive cycles, the first frequency f1 of the switching frequency calculation module 220 is higher than the intermittent mode set frequency (i.e., the switching signal of the pulse width modulation module 250 is always logic low), then the switching cycle counting module 240 adds 3 to the cycle count value (repeatedly adding 1 and 3 times). When the cycle count value equals a predetermined number of cycles (set by the switching cycle count module 240), the switching cycle count module 240 transmits a command signal S1 to the pulse width modulation module 250. Upon receiving the command signal S1, the pulse width modulation module 250 issues a one-cycle switching signal. The frequency of the switching signal issued by the pulse width modulation module 250 is the first frequency f1 of the switching frequency calculation module. When the pulse width modulation module 250 issues a one-cycle switching signal, the switching cycle count module 240 resets the cycle count value (e.g., returns it to zero). Alternatively, if the cycle count value is still lower than the predetermined number of cycles (set by the switching cycle count module 240), and if the first frequency f1 of the switching frequency calculation module 220 is lower than the intermittent mode setting frequency (i.e., the switching signal of the pulse width modulation module 250 is output normally), the switching cycle count module 240 resets the cycle count value.

[0039] The pulse width modulation module 250 is coupled to the switching frequency calculation module 220, the intermittent mode control module 230, and the switching cycle counting module 240. Based on the first frequency f1 of the switching frequency calculation module 220, the control signal of the intermittent mode control module 230, and the command signal S1 of the switching cycle counting module 240, the pulse width modulation module 250 generates a switching signal (PWM signal) of the corresponding frequency, which is sent to the power switch 110 to control the on or off of the internal switch of the power switch 110.

[0040] The switch cycle count adjustment module 260 is coupled to the switch cycle count module 240 and the switch frequency calculation module 220. Based on the first frequency f1 of the switch frequency calculation module 220, the switch cycle count adjustment module 260 dynamically adjusts the predetermined number of cycles set by the switch cycle count module 240. For example, when the first frequency f1 of the switch frequency calculation module 220 is higher than a reference frequency (the reference frequency is manually set and is higher than the intermittent mode setting frequency), the switch cycle count adjustment module 260 increases the predetermined number of cycles set by the switch cycle count module 240 (e.g., but not limited to, the predetermined number of cycles set by the switch cycle count module 240 is increased by a predetermined cycle count value (e.g., but not limited to, 1)); and when the first frequency f1 of the switch frequency calculation module 220 is lower than the reference frequency, the switch cycle count adjustment module 260 decreases the predetermined number of cycles set by the switch cycle count module 240 (e.g., but not limited to, the predetermined number of cycles set by the switch cycle count module 240 is decreased by a predetermined cycle count value (e.g., but not limited to, 1)). The switch cycle count adjustment module 260 can issue a fast interrupt to adjust (increase or decrease) the predetermined number of cycles set by the switch cycle count module 240.

[0041] Figure 3 This is a flowchart of a power conversion circuit control method according to an embodiment of the present invention. In step S31, a first frequency f1 is calculated based on an error value. In step S32, a pulse width modulation module is controlled to generate a switching signal based on the first frequency f1 and an intermittent mode set frequency. In step S33, a cycle count value is generated based on whether the first frequency f1 is higher than the intermittent mode set frequency. In step S34, based on the cycle count value and a predetermined number of cycles, it is determined whether to transmit a command signal S1 to the pulse width modulation module. After receiving the command signal S1, the pulse width modulation module sends out the switching signal for one cycle.

[0042] In the above embodiments of the present invention, the settling time of the output voltage VOUT of the power conversion circuit 100 can be increased, for example, from 2ms to 50ms, while ensuring the linearity of the soft-start process of the output voltage.

[0043] In the above embodiments of the present invention, the inrush current (including output current and resonant current) of the soft-start process of the output voltage can be effectively reduced, thereby reducing the stress on the components.

[0044] In the above embodiments of the present invention, the control method described above can not only make the rise of the reference value of the output voltage more linear, but also reduce the internal software logic running time of the controller.

[0045] In the above embodiments of the present invention, the control method described above does not add any additional hardware circuitry to the controller (that is, the control method of the above embodiments of the present invention can be achieved using a DSP hardware architecture). Therefore, it does not increase the hardware cost of the power conversion circuit, nor does it increase the difficulty of PCB (printed circuit board) layout.

[0046] The foregoing mainly describes the solutions provided in the embodiments of the present invention from the perspective of power conversion circuit control. It is understood that, to achieve the above functions, the power conversion circuit and / or power conversion circuit controller include corresponding hardware structures and / or software modules for performing the functions. Those skilled in the art should readily recognize that, in conjunction with the units and algorithm steps of the embodiments described in this specification, the embodiments of the present invention can be implemented in hardware or a combination of hardware and software. Whether the function is performed by hardware or by software-driven hardware depends on the specific application and design perspective of the technical solution. Those skilled in the art can use different methods to implement the functions described in the above embodiments, all of which are within the spirit and scope of the present invention.

[0047] Furthermore, in this embodiment of the invention, the power conversion circuit and / or power conversion circuit controller can be divided into functional modules based on the aforementioned method examples. For example, each functional module can be obtained by dividing according to each corresponding function, or two or more functions can be integrated into one functional module. The integrated module can be implemented in hardware or as a software functional module. It should be noted that in this embodiment of the invention, the division into modules is only an example and represents a logical functional division. In actual implementation, other division methods can be used.

[0048] While the invention may describe many specific details, these should not be construed as limiting the scope of the claimed invention, but rather as descriptions of the characteristics of particular embodiments. In this description, certain features described in the context of a single embodiment may also be implemented in combination in that single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments. Furthermore, while features may initially be described as functioning in certain combinations, or even initially described as such combinations, in some cases one or more features may be removed from that combination, and the described combination may be for a sub-combination or a variation thereof. Similarly, while operations are depicted in the figures as being performed in a specific order, this should not be construed as requiring these operations to be performed in the specific order or sequence shown, or that all depicted operations must be performed to achieve the desired result.

[0049] Although the above embodiments of the present invention only disclose some examples and implementations, changes, modifications, and enhancements can be made to the examples, implementations, and other implementations based on the disclosed content.

[0050] In summary, although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A power conversion circuit controller, characterized in that, include: A switching frequency calculation module calculates a first frequency based on an error value; One pulse width modulation module; An intermittent mode control module is coupled to the switching frequency calculation module and the pulse width modulation module. According to the first frequency and an intermittent mode set frequency, the intermittent mode control module controls the pulse width modulation module to generate a switching signal. as well as A switching cycle counting module is coupled to the intermittent mode control module and the pulse width modulation module. Based on whether the first frequency is higher than the intermittent mode set frequency, the switching cycle counting module generates a cycle count value. Based on the cycle count value and a predetermined number of cycles, the switching cycle counting module determines whether to send a command signal to the pulse width modulation module. After receiving the command signal, the pulse width modulation module sends out the switching signal for one cycle.

2. The power conversion circuit controller as described in claim 1, characterized in that, The switching frequency of the switching signal is the first frequency.

3. The power conversion circuit controller as described in claim 1, characterized in that, Including: An error analog-to-digital converter, coupled to the switching frequency calculation module, compares a reference value with an output voltage to generate the error value.

4. The power conversion circuit controller as described in claim 3, characterized in that, The reference value is a ramp voltage with a ramp waveform.

5. The power conversion circuit controller as described in claim 1, characterized in that, Including: A switch cycle counting adjustment module is coupled to the switch cycle counting module and the switch frequency calculation module, and adjusts the predetermined number of cycles according to the first frequency.

6. The power conversion circuit controller as described in claim 5, characterized in that, When the first frequency is higher than a reference frequency, the switching cycle counting adjustment module increases the predetermined number of cycles; When the first frequency is lower than the reference frequency, the switching cycle count adjustment module reduces the predetermined number of cycles; and The reference frequency is higher than the frequency set for the intermittent mode.

7. The power conversion circuit controller as described in claim 1, characterized in that, When the first frequency is higher than the intermittent mode set frequency, the intermittent mode control module controls the pulse width modulation module to ensure that the switching signal generated by the pulse width modulation module is always logic low, and When the first frequency is lower than the intermittent mode set frequency, the intermittent mode control module controls the pulse width modulation module to output the switching signal.

8. The power conversion circuit controller as described in claim 1, characterized in that, When the first frequency is higher than the intermittent mode set frequency within a cycle, the switching cycle counting module increments the cycle count value by a predetermined cycle count value; and When the cycle count value is equal to the predetermined number of cycles, the switching cycle count module transmits the instruction signal to the pulse width modulation module.

9. The power conversion circuit controller as described in claim 8, characterized in that, When the switching cycle counting module transmits the command signal to the pulse width modulation module, the switching cycle counting module resets the cycle count value; and When the cycle count value is lower than the predetermined number of cycles, and the first frequency is lower than the intermittent mode set frequency, the switching cycle count module resets the cycle count value.

10. A power conversion circuit control method, characterized in that, include: A first frequency is calculated based on an error value; Based on the first frequency and an intermittent mode set frequency, a pulse width modulation module is controlled to generate a switching signal; Based on whether the first frequency is higher than the frequency set by the intermittent mode, a one-cycle count value is generated; and Based on the cycle count value and a predetermined number of cycles, it is determined whether to transmit a command signal to the pulse width modulation module. After receiving the command signal, the pulse width modulation module sends out the switching signal for one cycle.

11. The power conversion circuit control method as described in claim 10, characterized in that, The switching frequency of the switching signal is the first frequency.

12. The power conversion circuit control method as described in claim 10, characterized in that, Including: A reference value is compared with an output voltage to generate the error value.

13. The power conversion circuit control method as described in claim 12, characterized in that, The reference value is a ramp voltage with a ramp waveform.

14. The power conversion circuit control method as described in claim 10, characterized in that, Including: The predetermined number of cycles is adjusted according to the first frequency.

15. The power conversion circuit control method as described in claim 14, characterized in that, When the first frequency is higher than a reference frequency, the predetermined number of cycles is increased; When the first frequency is lower than the reference frequency, the predetermined number of cycles is reduced; and The reference frequency is higher than the frequency set for the intermittent mode.

16. The power conversion circuit control method as described in claim 10, characterized in that, When the first frequency is higher than the intermittent mode set frequency, the pulse width modulation module is controlled to ensure that the switching signal generated by the pulse width modulation module is always logic low, and... When the first frequency is lower than the intermittent mode set frequency, the pulse width modulation module is controlled to output the switching signal.

17. The power conversion circuit control method as described in claim 10, characterized in that, When the first frequency is higher than the intermittent mode set frequency within a cycle, the cycle count value is increased by a predetermined cycle count value; and When the cycle count value is equal to the predetermined number of cycles, the instruction signal is transmitted to the pulse width modulation module.

18. The power conversion circuit control method as described in claim 17, characterized in that, When the command signal is transmitted to the pulse width modulation module, the period count value is reset; and When the cycle count value is lower than the predetermined number of cycles, and the first frequency is lower than the set frequency of the intermittent mode, the cycle count value is reset.

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