Multi-phase circuit control method and multi-phase control circuit

Abstract

The invention relates to the technical field of multi-phase circuits, in particular to a control method of a multi-phase circuit and a multi-phase control circuit. The control method of the multi-phase circuit comprises the following steps: sampling the total working current of the multi-phase circuit, and determining the current working phase number of the multi-phase control circuit; determining a PWM signal overlapping degree according to an input source voltage, a reference voltage and the current working phase number; determining a corresponding initial slope compensation slope according to the current working phase number; determining a slope compensation slope to be adjusted according to the PWM signal overlapping degree and the initial slope compensation slope; generating a slope signal based on the to-be-adjusted slope compensation slope; and generating a PWM signal of each phase according to the ramp signal, the total working current, the output voltage of the multi-phase circuit, the reference voltage and the current working phase number. According to the control method of the multi-phase circuit, subharmonic oscillation can be avoided when PWM signals of all phases of the multi-phase circuit are overlapped.

Description

Technical Field

[0001] This application relates to the technical field of multiphase circuits, and particularly to a control method for a multiphase circuit and a multiphase control circuit. Background Art

[0002] In switching power supply technology, in order to meet the current requirements of high-power loads, two or more phases of a multiphase controller are usually used to meet the high-load current requirements.

[0003] Multiphase controllers usually adopt fixed-frequency PID control or constant on-time control mode. Among them, the constant on-time control multiphase controller is widely used in various industrial applications due to its high light-load efficiency, simple implementation, fast transient response, etc. However, when using ceramic capacitors, due to the phase lag of the capacitor voltage relative to the inductor current, subharmonic oscillations will occur during the control process. To solve the instability problem, slope compensation is usually adopted, which is achieved by climbing at a fixed slope during the PWM off stage and resetting to a fixed level when PWM is on.

[0004] In the prior art, since the multiphase controller works in different phases and the system transfer function is different in different phases, different slope compensation slopes are set for different phases to eliminate subharmonic oscillations in different phases. However, although this method avoids subharmonic oscillations to a certain extent, when the PWM signals overlap, there is still a risk of system oscillation when using the original slope compensation slope. Summary of the Invention

[0005] In order to solve the deficiencies of the prior art, the purpose of this application is to provide a control method for a multiphase circuit and a multiphase control circuit to avoid subharmonic oscillations when the PWM signals of each phase in the multiphase circuit overlap.

[0006] To achieve the above purpose, this application provides a control method for a multiphase circuit, including: Phase-sample the total operating current of the multiphase circuit to determine the current number of operating phases of the multiphase control circuit; Determine the degree of overlap of the PWM signals according to the input source voltage, reference voltage, and the current number of operating phases; Determine the corresponding initial slope compensation slope according to the current number of operating phases; Determine the slope compensation slope to be adjusted according to the degree of overlap of the PWM signals and the initial slope compensation slope; Generate a ramp signal based on the slope compensation slope to be adjusted; Generate PWM signals for each phase according to the ramp signal, total operating current, output voltage of the multiphase circuit, reference voltage, and current number of operating phases.

[0007] Further, the specific steps for determining the overlapping degree of the PWM signal according to the input source voltage, the reference voltage, and the current number of working phases adopt the following formula: M = floor(VREF / Vin * n); Wherein, M is the overlapping degree, VREF is the reference voltage, Vin is the input source voltage, and n is the current number of working phases.

[0008] Further, the specific steps for determining the slope compensation slope to be adjusted according to the overlapping degree of the PWM signal and the initial slope compensation slope adopt the following formula: Se = Se_ini_n * (1 + k_n * M); Wherein, Se is the slope compensation slope to be adjusted, Se_ini_n is the initial slope compensation slope corresponding to the current number of working phases n, k_n is the adjustment gain of the current number of working phases n, and M is the overlapping degree.

[0009] Further, the specific steps for generating the PWM signals of each phase according to the ramp signal, the total working current, the output voltage of the multiphase circuit, the reference voltage, and the current number of working phases include: Generating a compensation signal according to the output voltage and the reference voltage of the multiphase circuit.

[0010] Further, the specific steps for generating the PWM signals of each phase according to the ramp signal, the total working current, the output voltage of the multiphase circuit, the reference voltage, and the current number of working phases include: Comparing the magnitudes of the first signal and the second signal, and when the first signal is less than the second signal, outputting a set signal with a high level, wherein the first signal is a superimposed signal of the output voltage and the total current sampling signal, and the second signal is a superimposed signal of the compensation signal and the ramp signal.

[0011] Furthermore, the method further includes: Splitting the set signal into the PWM conduction signals of each phase according to the current number of working phases and the set signal; Generating the corresponding PWM signals of each phase according to the PWM conduction signals of each phase and the set conduction time.

[0012] To achieve the above object, the present application further provides a multiphase control circuit, including: A phase number determination unit, configured to sample the total working current of the multiphase circuit as a total current sampling signal, and determine the current number of working phases of the multiphase control circuit; An overlapping degree determination unit, connected to the phase number determination unit, configured to determine the overlapping degree of the PWM signal and the initial slope compensation slope according to the input source voltage, the reference voltage, and the current number of working phases of the multiphase circuit, and further determine the slope compensation slope to be adjusted; A slope compensation unit, connected to the overlap degree determination unit, for generating a slope signal according to the slope compensation slope to be adjusted; A PWM control module, connected to the phase number determination unit and the slope compensation unit, for generating PWM signals of each phase of the multiphase circuit according to the slope signal, the total current sampling signal, the output voltage of the multiphase circuit, the reference voltage, and the current working phase number.

[0013] Further, the PWM control module includes: A compensation unit, for generating a compensation signal according to the output voltage and the reference voltage of the multiphase circuit; A first adder, for adding the output voltage and the total current sampling signal to obtain a first signal; A second adder, connected to the compensation unit and the slope compensation unit, for adding the compensation signal and the slope signal to obtain a second signal; A comparison unit, connected to the first adder and the second adder, for comparing the magnitudes of the first signal and the second signal, and outputting a high-level setting signal when the first signal is less than the second signal.

[0014] Further, the PWM control module further includes: A phase allocation unit, connected to the comparison unit and the phase number determination unit, for splitting the setting signal into PWM conduction signals corresponding to each phase according to the current working phase number; A PWM generation unit, connected to the phase allocation unit, for generating corresponding PWM signals of each phase according to the PWM conduction signal and the set conduction time.

[0015] To achieve the above object, the present application further provides a multiphase control chip, including: A multiphase control circuit as described above.

[0016] Compared with the prior art, the multiphase control circuit of the present application has the following beneficial effects: The multiphase circuit control method and the multiphase control circuit of the present application determine the current working phase number by sampling the total current, and then determine the real-time PWM overlap degree, and perform slope compensation in sequence, avoiding sub-harmonic oscillation when PWM signals overlap and using the original compensation slope, and improving stability.

[0017] Other features and advantages of the present application will be described in the subsequent description, and some of them will become obvious from the description, or will be understood by implementing the present application. Description of the Drawings

[0018] The accompanying drawings are used to provide a further understanding of the present application, and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application, and do not constitute a limitation to the present application. In the accompanying drawings: Figure 1 It is a schematic flowchart of the control method for the polyphase circuit in Embodiment 1 of the present application; Figure 2 It is a variation waveform diagram of the current working phase number and the total working current; Figure 3 It is a schematic waveform diagram of non-overlapping PWM signals in Embodiment 1 of the present application; Figure 4 It is a schematic waveform diagram of two-phase overlapping PWM signals in Embodiment 1 of the present application; Figure 5 It is a schematic diagram of the slope compensation slope in Embodiment 1 of the present application; Figure 6 It is a schematic structural diagram of the polyphase control circuit in Embodiment 2 of the present application; In the figure: 100 - PWM control module, 101 - phase number determination unit, 102 - overlap degree determination unit, 103 - slope compensation unit, 104 - compensation unit, 105 - first adder, 106 - second adder, 107 - comparison unit, 108 - phase distribution unit, 109 - PWM generation unit, 200 - phase drive circuit. Detailed implementation manners

[0019] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although some embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided to more thoroughly and completely understand the present application. It should be understood that the accompanying drawings and embodiments of the present application are only for exemplary purposes and are not used to limit the protection scope of the present application.

[0020] It should be understood that the steps recited in the method embodiments of the present application can be executed in different orders and / or in parallel. In addition, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present application is not limited in this regard.

[0021] The term "including" and its variations used herein are open-ended, that is, "including but not limited to". The term "based on" is "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The relevant definitions of other terms will be given in the following description.

[0022] It should be noted that the modifications of "one" and "multiple" mentioned in this application are illustrative rather than restrictive. Those skilled in the art should understand that unless otherwise clearly specified in the context, it should be understood as "one or more". "Multiple" should be understood as two or more.

[0023] Next, the embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0024] Embodiment 1 An embodiment of the present application provides a control method for a multiphase circuit, which can avoid oscillation and has good stability when the PWM signals of the multiphase circuit overlap.

[0025] Figure 1 is a schematic flowchart of the control method for the multiphase circuit according to Embodiment 1 of the present application. As Figure 1 shown, the control method for the multiphase circuit of the present application includes: S101: Sample the total operating current of the multiphase circuit to determine the current number of operating phases of the multiphase control circuit; In this embodiment, the current number of operating phases can be determined by comparing the total operating current with the current threshold corresponding to each phase.

[0026] Exemplarily, refer to Figure 2 , Figure 2 is a waveform diagram of the change between the current number of operating phases and the total operating current. As Figure 2 shown, when the total current increases to be greater than the threshold th1’, the system operates in two phases. When the total current decreases to be less than the threshold th1, the system operates in one phase.

[0027] S102: Determine the degree of overlap of the PWM signals according to the input source voltage, the reference voltage, and the current number of operating phases; In this embodiment, the specific steps for determining the degree of overlap of the PWM signals according to the input source voltage, the reference voltage, and the current number of operating phases are as follows: M = floor(VREF / Vin * n); where M is the degree of overlap, VREF is the reference voltage, Vin is the input source voltage, and n is the current number of operating phases.

[0028] It can be understood that floor is the floor function. When M is equal to 0, it means there is no overlap of PWM signals. When M is greater than 0, it means there is overlap of PWM signals in (M + 1) phases.

[0029] Exemplarily, refer to Figures 3 - 4 , Figure 3 is a schematic waveform diagram of no overlap of PWM signals according to Embodiment 1 of the present application. Figure 4Schematic diagram of the overlapping of two phases of a PWM signal for Embodiment 1 of the present application.

[0030] Step S103: Determine the corresponding initial ramp compensation slope according to the current number of working phases; It can be understood that the initial ramp compensation slope is pre-configured in a one-to-one correspondence with the current number of working phases.

[0031] Step S104: Determine the ramp compensation slope to be adjusted according to the overlapping degree of the PWM signal and the initial ramp compensation slope; In this embodiment, the specific steps for determining the ramp compensation slope to be adjusted according to the overlapping degree of the PWM signal and the initial ramp compensation slope adopt the following formula: Se = Se_ini_n * (1 + k_n * M); Where Se is the ramp compensation slope to be adjusted, Se_ini_n is the initial ramp compensation slope corresponding to the current number of working phases n, k_n is the adjustment gain of the current number of working phases n, and M is the overlapping degree.

[0032] It should be noted that the adjustment gains for different numbers of working phases can be set independently.

[0033] It can be understood that the larger the number of overlapping phases, the larger the corresponding ramp compensation slope to be adjusted.

[0034] Exemplarily, refer to Figure 5 , Figure 5 Schematic diagram of a ramp compensation slope for Embodiment 1 of the present application. As shown in Figure 5 , the ramp compensation slope to be adjusted is controlled by both the number of working phases and the overlapping degree.

[0035] Step S105: Generate a ramp signal based on the ramp compensation slope to be adjusted; Step S106: Generate PWM signals for each phase according to the ramp signal, the total working current, the output voltage of the multi-phase circuit, the reference voltage, and the current number of working phases.

[0036] The specific steps include: Generate a compensation signal according to the output voltage of the multi-phase circuit and the reference voltage; Compare the magnitudes of the first signal and the second signal. When the first signal is less than the second signal, output a set signal with a high level, where the first signal is the superimposed signal of the output voltage and the total current sampling signal, and the second signal is the superimposed signal of the compensation signal and the ramp signal; According to the current number of working phases and the set signal, split the set signal into PWM conduction signals for each phase; Generate the corresponding PWM signals for each phase according to the PWM conduction signals of each phase and the set conduction time.

[0037] Embodiment 2 An embodiment of the present application provides a multiphase control circuit, which can avoid oscillation and has good stability when the PWM signals of the multiphase circuit overlap.

[0038] Figure 6 It is a schematic structural diagram of the multiphase control circuit according to Embodiment 2 of the present application, as Figure 6 shown, the multiphase control circuit of the present application includes: A phase number determination unit 101, configured to sample the total working current of the multiphase circuit as a total current sampling signal, and determine the current working phase number n of the multiphase control circuit; As Figure 6 shown, the multiphase circuit is composed of a plurality of phase drive circuits 200 connected in parallel, and each phase drive circuit is respectively controlled by the PWM signal of the corresponding phase. Among them, the input source voltage of the multiphase circuit is Vin, the output voltage is Vo, and the output end of the multiphase circuit is connected with a load RL.

[0039] In this embodiment, the phase number determination unit 101 samples the total current of each phase through an adder 110.

[0040] It should be noted that after the adder 110 samples the total current Isum and applies a gain Ri, the true total current sampling signal Isum*Ri is output to the phase number determination unit 101.

[0041] An overlap degree determination unit 102, connected to the phase number determination unit 101, is configured to determine the PWM signal overlap degree M and the initial ramp compensation slope according to the input source voltage Vin, the reference voltage VERF of the multiphase circuit, and the current working phase number n, and further determine the slope Se of the ramp compensation to be adjusted; In this embodiment, the overlap degree determination unit 102 determines the PWM signal overlap degree M and the slope Se of the ramp compensation to be adjusted through the following formula: M = floor(VREF / Vin*n); Wherein, M is the overlap degree, VREF is the reference voltage, Vin is the input source voltage, and n is the current working phase number.

[0042] Se = Se_ini_n*(1 + k_n*M); Wherein, Se is the slope of the ramp compensation to be adjusted, Se_ini_n is the initial ramp compensation slope corresponding to the current working phase number n, k_n is the adjustment gain of the current working phase number n, and M is the overlap degree.

[0043] The ramp compensation unit 103 is connected to the overlap degree determination unit 102 and is used to generate a ramp signal slope for the to-be-adjusted ramp compensation slope Se. The PWM control module 100 is connected to the phase number determination unit 101 and the ramp compensation unit 103, and is used to generate PWM signals for each phase of the multiphase circuit according to the ramp signal slope, the total current sampling signal Isum*Ri, the output voltage Vo of the multiphase circuit, the reference voltage VREF, and the current working phase number n.

[0044] In this embodiment, the PWM control module 100 includes: The compensation unit 104 is used to generate a compensation signal Vc according to the output voltage Vo of the multiphase circuit and the reference voltage VREF. The first adder 105 is used to superimpose the output voltage V0 and the total current sampling signal Isum*Ri into a first signal setn. The second adder 106 is connected to the compensation unit 104 and the ramp compensation unit 103, and is used to superimpose the compensation signal Vc and the ramp signal slope into a second signal setp. The comparison unit 107 is connected to the first adder 105 and the second adder 106, and is used to compare the magnitudes of the first signal setn and the second signal setp. When the first signal setn is less than the second signal setp, a high-level setting signal set is output.

[0045] The phase allocation unit 108 is connected to the comparison unit 107 and the phase number determination unit 101, and is used to split the setting signal set into PWM conduction signals on_flag1~on_flagN corresponding to each phase according to the current working phase number n. The PWM generation unit 109 is connected to the phase allocation unit 108, and is used to generate corresponding PWM signals PWM1~PWMN for each phase according to the PWM conduction signals on_flag1~on_flagN and the set conduction time.

[0046] Embodiment 3 An embodiment of the present application provides a multiphase control circuit chip, including the multiphase control circuit described in Embodiment 2.

[0047] The above description is only partial embodiments of the present application and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of disclosure involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept. For example, the technical solutions formed by mutually replacing the above features with the technical features (but not limited to) having similar functions disclosed in the present application.

[0048] In addition, although the operations are depicted in a particular order, this should not be construed as requiring that the operations be performed in the particular order shown or in sequential order. In certain environments, multitasking and parallel processing may be advantageous. Similarly, although a number of specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the present application. Certain features described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, the various features described in the context of a single embodiment may also be implemented separately or in any suitable sub-combination in multiple embodiments.

[0049] Although the subject matter has been described in language specific to structural features and / or methodological logical acts, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. On the contrary, the specific features and acts described above are merely example forms for implementing the claims.

Claims

1. A control method for a multi-phase circuit, characterized in that: include: Sampling the total working current of the multi-phase circuit to determine the current working phase number of the multi-phase control circuit; Determining the degree of PWM signal overlap according to the input source voltage, the reference voltage and the current number of working phases; Determining a corresponding initial slope compensation slope according to the current working phase number; Determining a slope compensation slope to be adjusted according to the PWM signal overlap degree and the initial slope compensation slope; generating a ramp signal based on the slope compensation slope to be adjusted; A PWM signal of each phase is generated according to the ramp signal, the total working current, the output voltage of the multi-phase circuit, the reference voltage and the current working phase number.

2. The multi-phase circuit control method according to claim 1, characterized in that: The specific step of determining the degree of overlap of the PWM signal according to the input source voltage, the reference voltage and the current working phase number adopts the following formula: M = floor (VREF / Vin*n); Among them, M is the overlap degree, VREF is the reference voltage, Vin is the input source voltage, and n is the current working phase number.

3. The control method of a multi-phase circuit according to claim 2, characterized in that: The specific step of determining the slope compensation slope to be adjusted according to the PWM signal overlap degree and the initial slope compensation slope adopts the following formula: Se = Se_ini_n*(1+k_n*M); Among them, Se is the slope compensation slope to be adjusted, Se_ini_n is the initial slope compensation slope corresponding to the current working phase number n, k_n is the adjustment gain of the current working phase number n, and M is the overlap degree.

4. The control method of a multi-phase circuit according to claim 1, characterized in that: The specific steps of generating the PWM signal of each phase according to the ramp signal, the total working current, the output voltage of the multi-phase circuit, the reference voltage and the current working phase number include: A compensation signal is generated according to the output voltage of the multi-phase circuit and a reference voltage.

5. The multi-phase circuit control method according to claim 1, characterized in that: The specific steps of generating the PWM signal of each phase according to the ramp signal, the total working current, the output voltage of the multi-phase circuit, the reference voltage and the current working phase number include: Compare the sizes of the first signal and the second signal, and when the first signal is smaller than the second signal, output a high-level setting signal, wherein the first signal is a superposition signal of the output voltage and the total current sampling signal, and the second signal is a superposition signal of the compensation signal and the ramp signal.

6. The control method of a multi-phase circuit according to claim 1, characterized in that: The method further comprises: According to the current working phase number and the setting signal, the setting signal is split into PWM conduction signals of each phase; According to the PWM conduction signal of each phase and the set conduction time, the corresponding PWM signals are generated.

7. A multi-phase control circuit for controlling a multi-phase circuit, characterized in that: include: A phase number determination unit, used for sampling the total working current of the multi-phase circuit as a total current sampling signal, and determining the current working phase number of the multi-phase control circuit; an overlap degree determination unit, connected to the phase number determination unit, for determining the overlap degree of the PWM signal and the initial slope compensation slope according to the input source voltage of the multi-phase circuit, the reference voltage and the current working phase number, and then determining the slope compensation slope to be adjusted; a slope compensation unit, connected to the overlap degree determination unit, and configured to generate a ramp signal according to the slope compensation slope to be adjusted; The PWM control module is connected to the phase number determination unit and the slope compensation unit, and is used to generate a PWM signal for each phase of the multi-phase circuit according to the ramp signal, the total current sampling signal, the output voltage of the multi-phase circuit, the reference voltage and the current working phase number.

8. The multi-phase control circuit according to claim 7, characterized in that: The PWM control module comprises: A compensation unit, used for generating a compensation signal according to an output voltage of the multi-phase circuit and a reference voltage; A first adder, used for superimposing the output voltage and the total current sampling signal into a first signal; A second adder, connected to the compensation unit and the slope compensation unit, and configured to superimpose the compensation signal and the ramp signal into a second signal; The comparison unit is connected to the first adder and the second adder, and is used to compare the first signal with the second signal, and output a high-level setting signal when the first signal is smaller than the second signal.

9. The multi-phase control circuit according to claim 8, characterized in that: The PWM control module also includes: a phase distribution unit, connected to the comparison unit and the phase number determination unit, and configured to split the setting signal into PWM conduction signals corresponding to each phase according to the current working phase number; The PWM generating unit is connected to the phase allocating unit and is used to generate corresponding PWM signals according to the PWM on-time signal and the set on-time.

10. A multi-phase control circuit chip, characterized in that: A multi-phase control circuit comprising any one of claims 7 to 9.

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