阅读说明：本技术 用于计算开关时间的装置和方法 (Device and method for calculating switching time ) 是由 大竹修 古越隆一 于 2018-08-30 设计创作，主要内容包括：本发明实施例提供一种用于计算开关时间的装置和方法。所述装置包括：数字计算器,所述数字计算器用于根据输出电压信号以及在开关元件的接通期间检测到的电感电流信号计算下一个接通时间,并且根据所述下一个接通时间、输入电压信号和所述输出电压信号计算下一个关闭时间；以及信号发生器,所述信号发生器用于根据所述下一个接通时间和所述下一个关闭时间生成用于控制所述开关元件的脉冲宽度调制信号。因此,本发明实施例提供一种数字控制方式,不仅能够减少部件的数量和降低成本,而且可以用简单的结构改进检测精度。(The embodiment of the invention provides a device and a method for calculating switching time. The device comprises: a digital calculator for calculating a next on-time from an output voltage signal and an inductor current signal detected during on-time of a switching element, and calculating a next off-time from the next on-time, an input voltage signal, and the output voltage signal; and a signal generator for generating a pulse width modulation signal for controlling the switching element according to the next on-time and the next off-time. Therefore, the embodiment of the invention provides a digital control mode, which not only can reduce the number of parts and reduce the cost, but also can improve the detection precision by using a simple structure.)

1. An apparatus for calculating a switching time, the apparatus comprising:

a digital calculator for calculating a next on time from an output voltage signal and an inductor current signal detected during on-period of a switching element, and calculating a next off time from the next on time, an input voltage signal, and the output voltage signal; and

a signal generator for generating a pulse width modulation signal for controlling the switching element according to the next on-time and the next off-time.

2. The apparatus of claim 1, wherein the digital calculator is further configured to calculate an integration value based on an average value of the inductor current signal and the on-time, and to calculate the next on-time based on the integration value and the sensed inductor current signal.

3. The apparatus of claim 2, wherein the digital calculator calculates the next on-time using the following equation:

T_on[n+1]＝Ver/Id[n]；

where Ver represents a target integral value of the inductor current signal during the on-time of the (n + 1) th cycle and based on the output voltage signal, Id [ n [ [ n ]]Representing said detected inductor current signal during the on-time of the nth period, T_on[n+1]Representing the on-time of the (n + 1) th cycle.

4. The apparatus of claim 1, wherein the apparatus further comprises:

a first analog-to-digital converter for converting the inductor current signal to a digital value;

a second analog-to-digital converter for converting the input voltage signal to a digital value; and

a third analog-to-digital converter to convert the output voltage signal to a digital value.

5. The apparatus of claim 1, wherein the apparatus further comprises:

a current detection circuit for detecting the inductor current signal during an on-time of the switching element;

an input voltage detection circuit for detecting the input voltage signal; and

an output voltage detection circuit for detecting the output voltage signal;

wherein the current detection circuit is to detect the inductor current signal at least once during an on-time of the switching element.

6. The apparatus of claim 5, wherein the current detection circuit is to detect the inductor current signal at half the on-time;

and the digital calculator is configured to determine an average value of the inductor current signal based on detecting the inductor current signal at half the on-time.

7. The apparatus of claim 2, wherein the digital calculator calculates the integral value using the following formula:

Ver＝Id[n]×T_on[n]；

where Ver denotes the on-time period of the (n + 1) th cycleA target integral value of the inductor current signal and based on the output voltage signal, Id [ n [ ]]Representing the inductor current signal, T, detected at half the on-time of the nth cycle_on[n]Indicating the on-time of the nth cycle.

8. The apparatus of claim 1, wherein the digital calculator is further configured to calculate a differential voltage signal based on the input voltage signal and the output voltage signal, and calculate an error voltage signal based on the output voltage signal and a reference voltage signal;

wherein the digital calculator is further configured to calculate the next off time based on the next on time, the differential voltage signal, and the error voltage signal.

9. A power factor correcting converter, comprising:

a rectifier circuit for rectifying an alternating-current voltage received from an alternating-current power supply;

a series circuit for connection to the rectifying circuit and including at least an inductor and a switching element;

a current detection circuit for detecting an inductor current signal during an on-time of the switching element;

an input voltage detection circuit for detecting an input voltage signal;

an output voltage detection circuit for detecting an output voltage signal; and

a switch control circuit for controlling on/off of the switching element; wherein the switch control circuit comprises:

a digital calculator for calculating a next on-time from the output voltage signal and an inductor current signal detected during the on-period of the switching element, and calculating a next off-time from the next on-time, the input voltage signal, and the output voltage signal; and

a signal generator for generating a pulse width modulation signal for controlling the switching element according to the next on-time and the next off-time.

10. A method for calculating a switching time, the method comprising:

calculating a next on time from the output voltage signal and an inductor current signal detected during the on period of the switching element;

calculating a next turn-off time based on the next turn-on time, the input voltage signal, and the output voltage signal; and

generating a pulse width modulation signal for controlling the switching element according to the next on-time and the next off-time.

Technical Field

Embodiments of the present invention relate generally to power control circuits, and more particularly, to an apparatus and method for calculating switching time

Background

For harmonic current regulation, a Power Factor Correction (PFC) converter is typically added to the Power supply. Fig. 1 is a schematic diagram showing a PFC circuit in the related art. As shown in fig. 1, the PFC converter 100 includes a rectifier circuit 101, the rectifier circuit 101 being configured to rectify an ac voltage received from an ac power supply; and a series circuit 102, the series circuit 102 being for connection to the rectifying circuit 101 and including at least an inductor 1021 and a switching element 1022.

As shown in fig. 1, the PFC converter 100 may further include a capacitor C1, a diode D1, and a capacitor C2. As shown in fig. 1, the input voltage signal (Vin) and the output voltage signal (Vout) may be detected. Further, a current IL flows through the inductor 1021 and flows through the switching element 1022 when the switching element 1022 is turned ON (ON, which may also be referred to as open or conductive). A drive signal (Vgs) is also provided to control the switching element 1022.

Fig. 2 is a schematic diagram showing another PFC circuit in the prior art, in which an analog control scheme is provided. As shown in fig. 2, the drive signal (Vgs) is provided by an analog control circuit 201. The analog control circuit 201 at least comprises three analog comparators and a multiplier; further, the phase adjustment capacitor 202 and the gain adjustment resistor 203 need to be independently configured to perform phase adjustment or gain adjustment. Therefore, it is required to reduce the number of parts and to reduce the cost.

Fig. 3 is a schematic diagram illustrating another PFC circuit in the prior art in which a combination of analog and digital is provided. As shown in fig. 3, the drive signal (Vgs) is provided by an analog/digital control circuit 301. The analog/digital control circuit 301 includes at least a Central Processing Unit (CPU), a Pulse Width Modulation (PWM) circuit, and an analog comparator 302. In addition, the analog/digital control circuit 301 may further include an analog-to-digital converter (ADC) and a digital-to-analog converter (DAC).

In contrast to the analog control approach of fig. 2, a combined analog and digital approach is provided in fig. 3. For a combined analog and digital manner, the analog comparator 302 compares the inductor current IL _1 detected at the switching element 303 with a prescribed value to control on/OFF (OFF, which may also be referred to as OFF or cut OFF, or the like) of the switching element 303.

Reference 1: US2012/0057382A 1.

The summary of the section introduces aspects that are intended to provide a better understanding of embodiments of the invention. Accordingly, the statements of this section are to be read in this light and are not to be construed as admissions of what is or is not prior art.

Disclosure of Invention

The inventors have found that for the combined analog and digital approach, it is necessary to detect (or sample) the inductor current immediately after the switching element is turned on, and in this case, the inrush current is usually generated by the recovery current of the diode D1, so that a detection error may occur.

Further, for the analog and digital combination, an analog comparator is required to turn off the switching element when the inductor current reaches a prescribed value, and therefore the number of components and cost are relatively high, and further reduction is required.

To address at least some of the problems discussed above, the present invention provides methods, apparatus and devices. The features and advantages of embodiments of the present invention should be understood by reading the following description of the embodiments, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the embodiments of the invention.

In general, embodiments of the invention provide an apparatus and method for calculating a switching time. It is desirable to reduce the number of parts and cost, and to improve detection accuracy with a simple structure.

According to a first aspect of embodiments of the present invention, there is provided an apparatus for calculating a switching time. The device includes: a digital calculator for calculating a next on time from the output voltage signal and an inductor current signal detected during on of the switching element, and calculating a next off time from the next on time, the input voltage signal, and the output voltage signal; and a signal generator for generating a pulse width modulation signal for controlling the switching element according to the next on-time and the next off-time.

In one embodiment, the digital calculator is further configured to calculate an integral value based on the average value of the inductor current signal and the on-time, and to calculate the next on-time based on the integral value and the detected inductor current signal.

In one embodiment, theThe digital calculator calculates the next on-time using the following formula: t is_on[n+1]＝Ver/Id[n](ii) a Where Ver represents a target integral value of the inductor current signal during the on-time of the (n + 1) th cycle and Id [ n ] based on the output voltage signal]Representing the sensed inductor current signal during the on-time of the nth cycle, T_on[n+1]Representing the on-time of the (n + 1) th cycle.

In one embodiment, the apparatus may further comprise: a first analog-to-digital converter for converting the inductor current signal to a digital value; a second analog-to-digital converter for converting the input voltage signal to a digital value; and a third analog-to-digital converter for converting the output voltage signal to a digital value.

In one embodiment, the apparatus may further comprise: a current detection circuit for detecting the inductor current signal during an on-time of the switching element; an input voltage detection circuit for detecting the input voltage signal; and an output voltage detection circuit for detecting the output voltage signal.

In one embodiment, the current detection circuit is configured to detect the inductor current signal at least once during an on-time of the switching element.

In one embodiment, the current detection circuit is configured to detect the inductor current signal at half the on-time; and the digital calculator is configured to determine an average value of the inductor current signal based on detecting the inductor current signal at half the on-time.

In one embodiment, the digital calculator calculates the integral value using the following formula: ver ═ Id [ n ]]×T_on[n](ii) a Where Ver represents a target integral value of the inductor current signal during the on-time of the (n + 1) th cycle and Id [ n ] based on the output voltage signal]Representing the inductor current signal, T, detected at half the on-time of the nth cycle_on[n]Indicating the on-time of the nth cycle.

In one embodiment, the digital calculator is further configured to calculate a differential voltage signal based on the input voltage signal and the output voltage signal, and calculate an error voltage signal based on the output voltage signal and a reference voltage signal.

In one embodiment, the digital calculator is further configured to calculate the next off-time based on the next on-time, the differential voltage signal, and the error voltage signal.

According to a second aspect of embodiments of the present invention, there is provided a power factor correcting converter comprising: a rectifier circuit for rectifying an alternating-current voltage received from an alternating-current power supply; a series circuit for connection to the rectifying circuit and including at least an inductor and a switching element; a current detection circuit for detecting an inductor current signal during an on-time of the switching element; an input voltage detection circuit for detecting an input voltage signal; an output voltage detection circuit for detecting an output voltage signal; and a switch control circuit for controlling on/off of the switching element.

The switch control circuit includes at least: a digital calculator for calculating a next on time from the output voltage signal and an inductor current signal detected during the on period of the switching element, and calculating a next off time from the next on time, the input voltage signal, and the output voltage signal; and a signal generator for generating a pulse width modulation signal for controlling the switching element according to the next on-time and the next off-time.

In one embodiment, the switch control circuit may further include: a first analog-to-digital converter for converting the inductor current signal to a digital value; a second analog-to-digital converter for converting the input voltage signal to a digital value; and a third analog-to-digital converter for converting the output voltage signal to a digital value.

According to a third aspect of embodiments of the present invention, there is provided a method for calculating a switching time. The method comprises the following steps: calculating a next on time from the output voltage signal and an inductor current signal detected during the on period of the switching element; calculating a next turn-off time based on the next turn-on time, the input voltage signal, and the output voltage signal; and generating a pulse width modulation signal for controlling the switching element according to the next on-time and the next off-time.

In one embodiment, the method may further comprise: an integral value is calculated from the average value of the inductor current signal and the on-time, and the next on-time is calculated from the integral value and the detected inductor current signal.

In one embodiment, the method may further comprise: calculating a differential voltage signal from the input voltage signal and the output voltage signal; and calculating an error voltage signal from the output voltage signal and the reference voltage signal. And calculating the next off time based on the next on time, the differential voltage signal, and the error voltage signal.

According to various embodiments of the present invention, the digital calculator is configured to calculate a next on-time from the output voltage signal and the inductor current signal detected during the on-period of the switching element, and to calculate a next off-time from the next on-time, the input voltage signal and the output voltage signal. Therefore, a digital control system is provided which can not only reduce the number of parts and reduce the cost, but also improve the detection accuracy with a simple structure.

Drawings

The foregoing and other aspects, features and advantages of various embodiments of the present invention will be more fully understood with reference to the following detailed description, taken by way of example, taken in conjunction with the accompanying drawings in which like reference numerals or letters are used to designate like or equivalent elements. The accompanying drawings are included to provide a further understanding of embodiments of the invention, and are not necessarily drawn to scale. In these figures:

fig. 1 is a schematic diagram showing a PFC circuit in the prior art;

fig. 2 is a schematic diagram showing another PFC circuit in the prior art;

fig. 3 is a schematic diagram showing another PFC circuit in the prior art;

FIG. 4 is a schematic diagram showing inductor current in steady state;

FIG. 5 is a schematic diagram showing inductor current in an unstable state;

fig. 6 is a schematic diagram showing a PFC converter 600 according to an embodiment of the present invention;

FIG. 7 is a schematic diagram showing the inductor current in the inductor;

FIG. 8 is a schematic diagram showing a drive signal from a signal generator;

FIG. 9 is a schematic diagram showing an input voltage signal and an output voltage signal;

FIG. 10 is a schematic diagram illustrating inductor current flow for an embodiment of the present invention;

fig. 11 is a diagram illustrating a method of calculating a switching time according to an embodiment of the present invention.

Detailed Description

The invention will be illustrated below with reference to a few examples. It should be understood that these examples are described only to enable those skilled in the art to better understand and practice the present invention, and are not intended to limit the scope of the present invention.

It will be understood that when an element is "connected to" or "coupled to" or "in contact with" another element, it can be directly connected or coupled to or in contact with the other element, and intervening elements may also be present. In contrast, when an element is "directly connected to" or "directly coupled to" or "directly in contact with" another element, there are no intervening elements present. Other words used to describe the relationship between elements (e.g., "between …" and "directly between …," and "adjacent" and "directly adjacent," etc.) should also be interpreted in a similar manner.

The terms "first" and "second" as used herein refer to different elements. The singular forms "a", "an" and "the" are intended to include the plural forms as well, unless expressly stated otherwise. The terms "comprising," "having," and/or "including," as used herein, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, and/or components, and/or groups thereof.

The term "based on" as used herein is to be understood as "based, at least in part, on". The term "cover" is understood to mean "at least partially cover". The terms "one embodiment" and "an embodiment" should be understood as "at least one embodiment". The term "another embodiment" should be understood as "at least another embodiment". Other definitions, whether explicit or implicit, are included in the description below.

In the present invention, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which exemplary embodiments belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

In order to operate in a stable state in a PFC converter, it is necessary that an inductor current IL flowing through an inductor of the PFC converter is stable. Fig. 4 is a schematic diagram showing the inductor current (IL) in a steady state. As shown in fig. 4, I1 may be equal (or nearly equal) to I3. Fig. 5 is a diagram showing the inductor current (IL) in an unstable state. As shown in FIG. 5, I2 is not equal to I4.

In the embodiment of the present invention, a digital control method is provided to perform stable control with a simple structure.