CN109245531B - Duty ratio determining method and device, and pulse width modulation signal generating method and device - Google Patents
Duty ratio determining method and device, and pulse width modulation signal generating method and device Download PDFInfo
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- CN109245531B CN109245531B CN201811268465.XA CN201811268465A CN109245531B CN 109245531 B CN109245531 B CN 109245531B CN 201811268465 A CN201811268465 A CN 201811268465A CN 109245531 B CN109245531 B CN 109245531B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/157—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators with digital control
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Abstract
The invention provides a duty ratio determining method and device and a pulse width modulation signal generating method and device. The duty cycle determination method comprises the following steps: acquisition in the k-1 periodDuty ratio d (k-2) of pulse width modulation signal, and inductor current i of DC converter in k-1 th periodL(k-1), and the input voltage Vg (k-1) of the DC converter in the k-1 th period; detecting the output voltage Vo (k-1) of the direct current converter in the k-1 th period; according to Vo (k-1), d (k-2), iL(k-1) and Vg (k-1), calculating the inductive current i of the DC converter in the k periodL(k) (ii) a Calculating the inductive reference current i of the DC converter in the k periodLref(k) (ii) a According to d (k-2), iL(k) And iLref(k) Calculating the duty ratio d (k-1) of the pulse width modulation signal in the k period; k is an integer greater than 1. The invention reduces the delay time.
Description
Technical Field
The invention relates to the technical field of direct current conversion, in particular to a duty ratio determining method and device and a pulse width modulation signal generating method and device.
Background
The driving circuit of the liquid crystal panel is composed of integrated circuits and resistors, capacitors, etc., and the operating voltage of each integrated circuit is provided by a PMIC (Power Management IC), which is a Power source, so that it is important to ensure the performance of the PMIC. The dc converter is a core component in the PMIC, and is a hot research focus of the PMIC at present.
The loop delay existing in the DC converter is divided into control delay and modulation delay, the control delay refers to the delay from the sampling start time of an analog-to-digital converter (ADC) to the time when a digital controller outputs a control signal, and the control delay can be further divided into delay t generated by the ADC (ADC)ADCAnd the delay generated by the digital controller. If the number of ADCs adopted by the DC converter is large, the delay t generated by the ADCsADCAnd also longer.
The basic principle of the existing method for confirming the duty ratio of the pulse width modulation signal in the direct current converter can be generalized to one-beat control, and the basic idea is to detect a state variable in the k-1 th period and calculate the duty ratio d (k-1) of the pulse width modulation signal in the k-th period through a control algorithm. Although the one-beat-delayed control method can eliminate the limitation of the duty ratio caused by the time delay, the one-beat delay exists, namely the duty ratio d (k-1) of the k-th period is obtained according to the state variable of the k-1-th beat, so that the control precision, the dynamic response and other performances of the circuit are influenced. In addition, the current control mode is dual-loop control, two ADCs are needed to sample and convert the current and the output voltage respectively, power consumption is increased, and delay generated by the ADCs is introduced into two loops.
Disclosure of Invention
The invention mainly aims to provide a duty ratio determining method and device, and a pulse width modulation signal generating method and device, and solves the problems of long delay time and high power consumption caused by the fact that two analog-to-digital converters are needed to respectively sample and convert current and output voltage to obtain the duty ratio of a pulse width modulation signal used in a direct current converter in the prior art.
In order to achieve the above object, the present invention provides a duty ratio determining method for determining a duty ratio of a pulse width modulation signal applied in a dc converter, the duty ratio determining method comprising:
acquiring the duty ratio d (k-2) of the pulse width modulation signal in the k-1 period and the inductive current i of the direct current converter in the k-1 periodL(k-1), and, the DC converterThe input voltage Vg (k-1) of the converter in the k-1 th period;
detecting the output voltage Vo (k-1) of the direct current converter in the k-1 th period;
according to Vo (k-1), d (k-2), iL(k-1) and Vg (k-1), and calculating the inductive current i of the DC converter in the k periodL(k)；
Calculating the inductance reference current i of the DC converter in the k periodLref(k)；
According to d (k-2), iL(k) And iLref(k) Calculating the duty ratio d (k-1) of the pulse width modulation signal in the k period; k is an integer greater than 1.
When implemented, said is according to Vo (k-1), d (k-2), iL(k-1) and Vg (k-1), and calculating the inductive current i of the DC converter in the k periodL(k) The method comprises the following steps:
i is calculated according to the following formulaL(k)：
iL(k)＝iL(k-1)+(Ts/L)×(Vg(k-1)×d(k-2)-Vo(k-1))；
Wherein Ts is a switching period of the dc converter, and L is an inductance value of an inductor included in the dc converter.
When implemented, said is according to d (k-2), iL(k) And iLref(k) The step of calculating the duty ratio d (k-1) of the pulse width modulation signal in the k period comprises the following steps:
d (k-1) is calculated according to the following formula:
d(k-1)＝d(k-2)+e(k)×L/Ts/Vg(k-1)；
e(k)＝iLref(k)-iL(k)；
wherein Ts is a switching period of the dc converter, and L is an inductance value of an inductor included in the dc converter.
In practice, the inductance reference current i of the DC converter in the k period is calculatedLref(k) The method comprises the following steps:
calculating Vs (k-1) according to d (k-2), Von (k-1) and Voff (k-1);
calculating i from Vs (k-1)Lref(k)；
And Vs (k-1) is the voltage at two ends of a switching transistor of which the control electrode is connected with the pulse width modulation signal in the (k-1) th period, Von (k-1) is the voltage at two ends of the switching transistor when the switching transistor is switched on in the (k-1) th period, and Voff (k-1) is the voltage at two ends of the switching transistor when the switching transistor is switched off in the (k-1) th period.
In the implementation, the direct current converter is a buck converter, Von (k-1) is equal to 0, Voff (k-1) is equal to Vg (k-1); or, the direct current converter is a boost converter, Von (k-1) is equal to 0, and Voff (k-1) is equal to Vo (k-1).
The present invention also provides a duty cycle determining module for determining a duty cycle of a pulse width modulation signal applied to a dc converter, the duty cycle determining module comprising:
an obtaining unit, configured to obtain a duty ratio d (k-2) of the pulse width modulation signal in a k-1 th period and an inductor current i of the dc converter in the k-1 th periodL(k-1), and an input voltage Vg (k-1) of the dc converter in the k-1 th cycle;
the detection unit is used for detecting the output voltage Vo (k-1) of the direct current converter in the k-1 th period;
an inductive current calculating unit for calculating the inductive current according to Vo (k-1), d (k-2), iL(k-1) and Vg (k-1), and calculating the inductive current i of the DC converter in the k periodL(k)；
A reference inductive current calculating unit for calculating a reference inductive current i of the DC converter in the k-th periodLref(k)；
A duty ratio calculation unit for calculating the duty ratio according to d (k-2) and iL(k) And iLref(k) Calculating the duty ratio d (k-1) of the pulse width modulation signal in the k period; k is a positive integer.
When implemented, the inductive current calculating unit is used for calculating i according to the following formulaL(k)：
iL(k)＝iL(k-1)+(Ts/L)×(Vg(k-1)×d(k-2)-Vo(k-1))；
Wherein Ts is a switching period of the dc converter, and L is an inductance value of an inductor included in the dc converter.
In practice, the duty ratio calculating unit is configured to calculate d (k-1) according to the following formula:
d(k-1)＝d(k-2)+e(k)×L/Ts/Vg(k-1)；
e(k)＝iLref(k)-iL(k)；
wherein Ts is a switching period of the dc converter, and L is an inductance value of an inductor included in the dc converter.
In practice, the inductance reference current calculating unit is used for calculating Vs (k-1) according to d (k-2), Von (k-1) and Voff (k-1) and calculating i according to Vs (k-1)Lref(k)；
And Vs (k-1) is the voltage at two ends of a switching transistor of which the control electrode is connected with the pulse width modulation signal in the (k-1) th period, Von (k-1) is the voltage at two ends of the switching transistor when the switching transistor is switched on in the (k-1) th period, and Voff (k-1) is the voltage at two ends of the switching transistor when the switching transistor is switched off in the (k-1) th period.
In the implementation, the direct current converter is a buck converter, Von (k-1) is equal to 0, Voff (k-1) is equal to Vg (k-1); or, the direct current converter is a boost converter, Von (k-1) is equal to 0, and Voff (k-1) is equal to Vo (k-1).
The invention also provides a pulse width modulation signal generation method, which comprises the duty ratio determination method to determine the duty ratio d (k-1) of the pulse width modulation signal applied to the direct current converter in the k period;
the pulse width modulation signal generation method further includes:
and generating a pulse width modulation signal applied to the direct current converter in the k period according to d (k-1).
The invention also provides a pulse width modulation signal generating device, which comprises a pulse width modulation signal generating unit and the duty ratio determining module;
the duty ratio determining module is used for determining the duty ratio d (k-1) of a pulse width modulation signal applied to the direct current converter in the k period;
the pulse width modulation signal generating unit is used for generating a pulse width modulation signal applied to the direct current converter in a k period according to d (k-1); k is a positive integer.
Compared with the prior art, the duty ratio determining method and device, the pulse width modulation signal generating method and device can reduce the loop delay generated by the control loop of the direct current converter (because one ADC is less adopted), simplify the design of the hardware circuit of the direct current converter, reduce the Power consumption, improve the performance of the direct current converter, and are more convenient for developers to carry out the time sequence adjustment of PMIC (Power Management IC) in the product debugging stage.
Drawings
FIG. 1 is a flow chart of a duty cycle determination method according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of one embodiment of a buck converter to which the duty cycle determination method of the present invention is applied;
FIG. 3 is a schematic diagram of a switching cycle and pulse width modulated signal;
fig. 4 is a block diagram of a duty ratio determining module according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The transistors used in all embodiments of the present invention may be transistors, thin film transistors, or field effect transistors or other devices with the same characteristics. In the embodiment of the present invention, in order to distinguish two poles of the transistor except the control pole, one pole is called a first pole, and the other pole is called a second pole.
In practical operation, when the transistor is a triode, the control electrode may be a base electrode, the first electrode may be a collector electrode, and the second electrode may be an emitter electrode; alternatively, the control electrode may be a base electrode, the first electrode may be an emitter electrode, and the second electrode may be a collector electrode.
In practical operation, when the transistor is a thin film transistor or a field effect transistor, the control electrode may be a gate electrode, the first electrode may be a drain electrode, and the second electrode may be a source electrode; alternatively, the control electrode may be a gate electrode, the first electrode may be a source electrode, and the second electrode may be a drain electrode.
The duty cycle determining method according to an embodiment of the present invention is configured to determine a duty cycle of a pulse width modulation signal applied to a dc converter, and as shown in fig. 1, the duty cycle determining method includes:
s1: acquiring the duty ratio d (k-2) of the pulse width modulation signal in the k-1 period and the inductive current i of the direct current converter in the k-1 periodL(k-1), and an input voltage Vg (k-1) of the dc converter in the k-1 th cycle;
s2: detecting the output voltage Vo (k-1) of the direct current converter in the k-1 th period;
s3: according to Vo (k-1), d (k-2), iL(k-1) and Vg (k-1), and calculating the inductive current i of the DC converter in the k periodL(k)；
S4: calculating the inductance reference current i of the DC converter in the k periodLref(k)；
S5: according to iL(k) And iLref(k) Calculating the duty ratio d (k-1) of the pulse width modulation signal in the k period; k is an integer greater than 1.
The duty ratio determining method provided by the embodiment of the invention is characterized in that the duty ratio is determined according to the value iL(k) And iLref(k) Calculating the duty ratio d (k-1) of the pulse width modulation signal in the k period, wherein iL(k) Is according to Vo (k-1), d (k-2), iL(k-1) and Vg (k-1) are calculated, instead of sampling the inductor current i of the DC converter in the k-1 period through ADC (analog-to-digital converter) in the k-1 period as in the prior artL(k-1), thereby reducing the loop delay generated by the control loop of the DC converter (because one ADC is less adopted), simplifying the design of the hardware circuit of the DC converter, reducing the power consumption, improving the performance of the DC converter, and moreThe time sequence adjustment of PMIC (Power Management IC) is convenient for developers to carry out in the product debugging stage.
In step S1, the acquired iL(k-1) can be calculated from the parameters of the k-2 th cycle.
In step S1 of the duty ratio determining method according to the embodiment of the present invention, an input voltage Vg (k-1) of the dc converter in the k-1 th cycle is: in the k-1 th period, the average voltage of the input voltage of the direct current converter;
in step S2 of the duty ratio determining method according to the embodiment of the present invention, the output voltage Vo (k-1) of the dc converter in the k-1 th cycle is: in the k-1 th period, the average voltage of the output voltage of the DC converter, the method for detecting Vo (k-1) can be as follows: and in the k-1 period, acquiring the output voltage of the direct current converter through the ADC at preset time intervals, and calculating the average voltage of the acquired output voltages, wherein the average voltage is Vo (k-1).
In step S4 of the duty ratio determining method according to the embodiment of the present invention, the dc converter has an inductive reference current i in the k-th periodLref(k) And the ideal reference current of the inductance current of the direct current converter in the k period is obtained.
The embodiment of the invention provides a novel duty ratio determining method without current sampling, a current sampling circuit is not needed, the method is different from the traditional lag one-beat control principle, and the method is not based on i obtained by samplingL(k-1) to calculate d (k-1), but i from d (k-2)L(k) And d (k-1) is calculated based thereon.
In particular, said terms Vo (k-1), d (k-2), iL(k-1) and Vg (k-1), and calculating the inductive current i of the DC converter in the k periodL(k) The steps may include:
i is calculated according to the following formulaL(k)：
iL(k)＝iL(k-1)+(Ts/L)×(Vg(k-1)×d(k-2)-Vo(k-1))；
Wherein Ts is a switching period of the dc converter, and L is an inductance value of an inductor included in the dc converter.
When in specific implementation, the formula Vo (k-1), d (k-2) and i can be conveniently obtained according toL(k-1) and Vg (k-1) are calculated to obtain iL(k) And a current sampling circuit is avoided.
In particular, said formula iL(k) And iLref(k) The step of calculating the duty ratio d (k-1) of the pulse width modulation signal in the k-th period may include:
d (k-1) is calculated according to the following formula:
d(k-1)＝d(k-2)+e(k)×L/Ts/Vg(k-1)；
e(k)＝iLref(k)-iL(k)；
wherein Ts is a switching period of the dc converter, and L is an inductance value of an inductor included in the dc converter.
When in specific implementation, the formula d (k-2) and i can be conveniently obtained according toL(k) And iLref(k) D (k-1) is calculated.
Specifically, the inductance reference current i of the direct current converter in the k period is calculatedLref(k) The steps may include:
calculating Vs (k-1) according to d (k-2), Von (k-1) and Voff (k-1);
calculating i from Vs (k-1)Lref(k)；
And Vs (k-1) is the voltage at two ends of a switching transistor of which the control electrode is connected with the pulse width modulation signal in the (k-1) th period, Von (k-1) is the voltage at two ends of the switching transistor when the switching transistor is switched on in the (k-1) th period, and Voff (k-1) is the voltage at two ends of the switching transistor when the switching transistor is switched off in the (k-1) th period.
In an embodiment of the present invention, the voltage across the switching transistor refers to: a voltage between a first pole of the switching transistor and a second pole of the switching transistor.
In a specific implementation, the step of calculating Vs (k-1) according to d (k-2), Von (k-1) and Voff (k-1) may include: vs (k-1) is calculated according to the following formula:
Vs(k-1)＝d(k-2)Von(k-1)+d’(k-2)Voff(k-1)；
where d '(k-2) is a parameter related to d (k-2), and d' (k-2) is 1-d (k-2).
In actual practice, Vs (k-1) can be conveniently calculated from d (k-2), Von (k-1), and Voff (k-1) and the equations above.
According to a specific embodiment, the dc converter is a buck converter, Von (k-1) is equal to 0, Voff (k-1) is equal to Vg (k-1); alternatively, the first and second electrodes may be,
according to another embodiment, the DC converter is a boost converter, Von (k-1) is equal to 0, Voff (k-1) is equal to Vo (k-1).
The circuit structure of the dc converter will be described below by taking the dc converter as an example of a buck converter.
As shown in fig. 2, an embodiment of the buck converter includes an input power Vin, a switching transistor MS, a diode Q, and a first resistor REAn inductor L and a second resistor RCA capacitor C and an output resistor R, wherein,
the grid of the switching transistor MS is connected with a PWM (pulse width modulation) signal;
the switching transistor MS is a field effect transistor;
the first end of the inductor L and the first resistor REA second end of the inductor L is connected with a first end of the output resistor R, and a second end of the output resistor R is connected with a ground end GND;
the input voltage of the buck converter is the voltage provided by the input power Vin;
the output voltage of the buck converter is the voltage between the first end of the output resistor R and the second end of the output resistor R;
in the k-1 period, Vo (k-1) is obtained by sampling through the analog-to-digital converter 20, and then Vs (k-1) is obtained by calculating through the voltage controller 21 according to Vo (k-1) and i is obtained by calculating according to Vs (k-1)Lref(k)；
I is calculated according to Vs (k-1)Lref(k) The method (b) is a conventional method, is well known to those skilled in the art, and is not described herein again.
I is calculated from Vo (k-1) by the current calculating circuit 22L(k)；
And then current controller 23 according to iLref(k) And iL(k) D (k-1) is obtained through calculation;
the PWM signal generation circuit 24 generates a corresponding k-th beat PWM signal according to d (k-1), and transmits the k-th beat PWM signal to the gate of the switching transistor MS in a k-th switching period.
In the embodiment shown in FIG. 2, Vo (k-1) is the output voltage of the DC converter in the k-1 period, iL(k) For the inductor current i of the DC converter in the k-th cycleLref(k) Is the inductance reference current of the DC converter in the k period, and Vs (k-1) is the voltage across a switching transistor MS in the DC converter in the k-1 period; k is an integer greater than 1.
As shown in fig. 3, a period denoted by Tk-1 is a k-1 th period, a period denoted by Tk is a k-th period, a time during which the k-1 th period continues and a time during which the k-th period continues are switching periods, PWM signals are shown by oblique lines, and a horizontal axis indicates time.
The pulse width modulation signal generation method provided by the embodiment of the invention comprises the duty ratio determination method, so as to determine the duty ratio d (k-1) of the pulse width modulation signal applied to the direct current converter in the k-th period;
the pulse width modulation signal generation method further includes:
and generating a pulse width modulation signal applied to the direct current converter in the k period according to d (k-1).
The method for generating the pulse width modulation signal according to the embodiment of the invention adopts the duty ratio determining method, can determine d (k-1), and generates the corresponding pulse width modulation signal according to d (k-1)
The duty cycle determining module according to an embodiment of the present invention is configured to determine a duty cycle of a pulse width modulation signal applied to a dc converter, and as shown in fig. 4, the duty cycle determining module includes:
an obtaining unit 41, configured to obtain a duty ratio d (k-2) of the pulse width modulation signal in a k-1 th period and an inductor current i of the dc converter in the k-1 th periodL(k-1), and, theThe input voltage Vg (k-1) of the direct current converter in the k-1 th period;
a detection unit 42 for detecting an output voltage Vo (k-1) of the dc converter in a k-1 th cycle;
an inductive current calculating unit 43 for calculating the inductive current according to Vo (k-1), d (k-2), iL(k-1) and Vg (k-1), and calculating the inductive current i of the DC converter in the k periodL(k)；
A reference inductor current calculating unit 44 for calculating a reference inductor current i of the dc converter in the k-th periodLref(k)；
A duty ratio calculation unit 45 for calculating a duty ratio according to iL(k) And iLref(k) Calculating the duty ratio d (k-1) of the pulse width modulation signal in the k period; k is a positive integer.
The duty ratio determining module provided by the embodiment of the invention is based on the iL(k) And iLref(k) Calculating the duty ratio d (k-1) of the pulse width modulation signal in the k period, wherein iL(k) Is according to Vo (k-1), d (k-2), iL(k-1) and Vg (k-1) are calculated, instead of sampling the inductor current i of the DC converter in the k-1 period through ADC (analog-to-digital converter) in the k-1 period as in the prior artL(k-1), thus can reduce the loop delay that the control loop of the direct-flow converter produces (because has used an ADC less), has simplified the design of the hardware circuit of the direct-flow converter, reduce the Power consumption, and promote the performance of the direct-flow converter, make things convenient for the developer to carry on the sequential adjustment of PMIC (Power Management IC, Power Management integrated circuit) in the product debugging stage more.
In specific implementation, the inductive current calculating unit is used for calculating i according to the following formulaL(k)：
iL(k)＝iL(k-1)+(Ts/L)×(Vg(k-1)×d(k-2)-Vo(k-1))；
Wherein Ts is a switching period of the dc converter, and L is an inductance value of an inductor included in the dc converter.
In a specific implementation, the duty ratio calculating unit is configured to calculate d (k-1) according to the following formula:
d(k-1)＝d(k-2)+e(k)×L/Ts/Vg(k-1)；
e(k)＝iLref(k)-iL(k)；
wherein Ts is a switching period of the dc converter, and L is an inductance value of an inductor included in the dc converter.
Specifically, the inductance reference current calculation unit may be configured to calculate Vs (k-1) from d (k-2), Von (k-1), and Voff (k-1), and calculate i from Vs (k-1)Lref(k)；
And Vs (k-1) is the voltage at two ends of a switching transistor of which the control electrode is connected with the pulse width modulation signal in the (k-1) th period, Von (k-1) is the voltage at two ends of the switching transistor when the switching transistor is switched on in the (k-1) th period, and Voff (k-1) is the voltage at two ends of the switching transistor when the switching transistor is switched off in the (k-1) th period.
In specific implementation, the direct current converter is a buck converter, Von (k-1) is equal to 0, Voff (k-1) is equal to Vg (k-1); alternatively, the first and second electrodes may be,
the direct current converter is a boost converter, Von (k-1) is equal to 0, and Voff (k-1) is equal to Vo (k-1).
The pulse width modulation signal generating device comprises a pulse width modulation signal generating unit and the duty ratio determining module;
the duty ratio determining module is used for determining the duty ratio d (k-1) of a pulse width modulation signal applied to the direct current converter in the k period;
the pulse width modulation signal generating unit is used for generating a pulse width modulation signal applied to the direct current converter in a k period according to d (k-1); k is a positive integer.
The pulse width modulation signal generating device determines d (k-1) through the duty ratio determining module, and then generates a pulse width modulation signal applied to the direct current converter in a k-th period according to d (k-1) through a pulse width modulation signal generating unit.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (6)
1. A duty cycle determination method for determining a duty cycle of a pulse width modulated signal applied in a dc converter, the duty cycle determination method comprising:
acquiring the duty ratio d (k-2) of the pulse width modulation signal in the k-1 period and the inductive current i of the direct current converter in the k-1 periodL(k-1), and an input voltage Vg (k-1) of the dc converter in the k-1 th cycle;
detecting the output voltage Vo (k-1) of the direct current converter in the k-1 th period;
according to Vo (k-1), d (k-2), iL(k-1) and Vg (k-1), and calculating the inductive current i of the DC converter in the k periodL(k)；
Calculating the inductance reference current i of the DC converter in the k periodLref(k)；
According to d (k-2), iL(k) And iLref(k) Calculating the duty ratio d (k-1) of the pulse width modulation signal in the k period; k is an integer greater than 1;
according to Vo (k-1), d (k-2), iL(k-1) and Vg (k-1), and calculating the inductive current i of the DC converter in the k periodL(k) The method comprises the following steps:
i is calculated according to the following formulaL(k)：
iL(k)＝iL(k-1)+(Ts/L)×(Vg(k-1)×d(k-2)-Vo(k-1))；
Wherein Ts is a switching period of the dc converter, and L is an inductance value of an inductor included in the dc converter;
said radicals being according to d (k-2), iL(k) And iLref(k) The step of calculating the duty ratio d (k-1) of the pulse width modulation signal in the k period comprises the following steps:
d (k-1) is calculated according to the following formula:
d(k-1)＝d(k-2)+e(k)×L/Ts/Vg(k-1)；
e(k)＝iLref(k)-iL(k)；
wherein Ts is a switching period of the dc converter, and L is an inductance value of an inductor included in the dc converter;
calculating the inductance reference current i of the DC converter in the k periodLref(k) The method comprises the following steps:
calculating Vs (k-1) according to d (k-2), Von (k-1) and Voff (k-1);
calculating i from Vs (k-1)Lref(k)；
Wherein Vs (k-1) is a voltage across a switching transistor of which a control electrode is connected to the pulse width modulation signal in the dc converter in the k-1 th cycle, Von (k-1) is a voltage across the switching transistor when the switching transistor is turned on in the k-1 th cycle, and Voff (k-1) is a voltage across the switching transistor when the switching transistor is turned off in the k-1 th cycle;
the step of calculating Vs (k-1) according to d (k-2), Von (k-1) and Voff (k-1) comprises: vs (k-1) is calculated according to the following formula:
Vs(k-1)＝d(k-2)Von(k-1)+d’(k-2)Voff(k-1)；
wherein d' (k-2) ═ 1-d (k-2).
2. The duty ratio determination method according to claim 1, wherein the dc converter is a buck converter, Von (k-1) is equal to 0, Voff (k-1) is equal to Vg (k-1); or, the direct current converter is a boost converter, Von (k-1) is equal to 0, and Voff (k-1) is equal to Vo (k-1).
3. A duty cycle determining module for determining a duty cycle of a pulse width modulated signal applied to a dc converter, the duty cycle determining module comprising:
an obtaining unit, configured to obtain a duty ratio d (k-2) of the pulse width modulation signal in a k-1 th period and an inductor current i of the dc converter in the k-1 th periodL(k-1), and an input voltage Vg (k-1) of the dc converter in the k-1 th cycle;
the detection unit is used for detecting the output voltage Vo (k-1) of the direct current converter in the k-1 th period;
inductive current calculating unitAccording to Vo (k-1), d (k-2), iL(k-1) and Vg (k-1), and calculating the inductive current i of the DC converter in the k periodL(k)；
A reference inductive current calculating unit for calculating a reference inductive current i of the DC converter in the k-th periodLref(k)；
A duty ratio calculation unit for calculating the duty ratio according to d (k-2) and iL(k) And iLref(k) Calculating the duty ratio d (k-1) of the pulse width modulation signal in the k period; k is a positive integer;
the inductive current calculating unit is used for calculating i according to the following formulaL(k)：
iL(k)＝iL(k-1)+(Ts/L)×(Vg(k-1)×d(k-2)-Vo(k-1))；
Wherein Ts is a switching period of the dc converter, and L is an inductance value of an inductor included in the dc converter;
the duty ratio calculating unit is used for calculating d (k-1) according to the following formula:
d(k-1)＝d(k-2)+e(k)×L/Ts/Vg(k-1)；
e(k)＝iLref(k)-iL(k)；
wherein Ts is a switching period of the dc converter, and L is an inductance value of an inductor included in the dc converter;
the inductance reference current calculation unit is used for calculating Vs (k-1) according to d (k-2), Von (k-1) and Voff (k-1) and calculating i according to Vs (k-1)Lref(k)；
Wherein Vs (k-1) is a voltage across a switching transistor of which a control electrode is connected to the pulse width modulation signal in the dc converter in the k-1 th cycle, Von (k-1) is a voltage across the switching transistor when the switching transistor is turned on in the k-1 th cycle, and Voff (k-1) is a voltage across the switching transistor when the switching transistor is turned off in the k-1 th cycle;
the inductance reference current calculating unit is specifically configured to calculate Vs (k-1) according to the following formula:
Vs(k-1)＝d(k-2)Von(k-1)+d’(k-2)Voff(k-1)；
wherein d' (k-2) ═ 1-d (k-2).
4. Duty cycle determination module according to claim 3, characterized in that the dc converter is a buck converter, Von (k-1) being equal to 0, Voff (k-1) being equal to Vg (k-1); or, the direct current converter is a boost converter, Von (k-1) is equal to 0, and Voff (k-1) is equal to Vo (k-1).
5. A pulse width modulation signal generation method comprising the duty ratio determination method according to claim 1 or 2 to determine a duty ratio d (k-1) of a pulse width modulation signal applied to a dc converter in a k-th period;
the pulse width modulation signal generation method further includes:
and generating a pulse width modulation signal applied to the direct current converter in the k period according to d (k-1).
6. A pulse width modulation signal generating apparatus comprising a pulse width modulation signal generating unit and the duty ratio determining module according to claim 3 or 4;
the duty ratio determining module is used for determining the duty ratio d (k-1) of a pulse width modulation signal applied to the direct current converter in the k period;
the pulse width modulation signal generating unit is used for generating a pulse width modulation signal applied to the direct current converter in a k period according to d (k-1); k is a positive integer.
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