TW201424215A - Multifunctional digital pulse width modulation controller - Google Patents

Abstract

The present invention provides a multifunctional digital pulse width modulation controller, comprising a pulse width modulation controller, a selection unit, a comparison unit, and a signal conversion unit, in which the selection unit comprises at least a selector; the comparison unit comprises at least a comparator; and, the signal conversion unit comprises at least one digital-to-analog converter; wherein the digital-to-analog converter generates the reference voltage and/or current; the comparator receives the reference voltage and/or current and compare with the feedback signals for generating the comparison signals; the selector selects one of the comparison signals to input to the pulse width modulation controller; and, the pulse width modulation controller may simultaneously receive other parameters set by the user or the system for controlling the characteristics of the digital pulse width modulation signals, so as to improve the overall electric operation characteristics of a load circuit.

Description

Multi-function digital pulse width modulation controller

The invention relates to a multi-function digital pulse width modulation controller, in particular to dynamically changing the resolution of a working area of a current pulse width modulation signal according to a change state of a working area of a previous pulse width modulation signal.

In the prior art, Pulse Width Modulation (PWM) technology mainly uses a pulse signal with a specific frequency to change the pulse width according to a specific condition to achieve signal modulation, and is driven by a pulse width modulation signal. Electrical device or load circuit, such as switching elements of light-emitting diodes, motors, power converters. Generally, the minimum adjustable unit of pulse width is called resolution, such as a pulse signal with a frequency of 100KHz, with 1/100K seconds. Resolution.

For the application for driving the two switching elements, the pulse width modulation technique generates two corresponding pulse signals, and the pulse widths are mutually aligned, that is, when the pulse of one pulse signal is high/low level, the pulse of the other pulse signal For the high/low level, the two switching elements that simultaneously turn on the load circuit can be prevented from causing a large current conduction and short circuit, resulting in permanent damage.

In order to achieve the above functions, the conventional method may include an analog circuit method and a digital circuit method. In the analog circuit mode, the PWM frequency is generated by the built-in oscillator, so it cannot be arbitrarily changed according to the actual application state, and in particular, the compensation of the internal amplifier in the feedback control cannot be changed. In addition, the output voltage and load range are also preset and are not easy to change.

For the current digital circuit mode with digital power function, it is mainly necessary to use very fast analog-to-digital (ADC) sampling to generate the required analog feedback signal, and then perform signal control via a digital signal processor engine (DSP engine). ratio Such as proportional-integral-derivative (PID) control. However, to achieve higher PWM resolution, the faster the operating frequency is required, and the ADC sampling rate is also very high, which leads to excessive cost and is difficult to achieve in practical applications.

In addition, conventional techniques are unable to provide a time segment that dynamically changes the two-pulse signal while being low-level to improve the electrical characteristics of the load, such as the average power consumption. Therefore, there is a need for a multi-function digital pulse width modulation controller that can dynamically change the resolution of the working area of the current pulse width modulation signal, thereby solving the above-mentioned problems of the conventional technology.

The main object of the present invention is to provide a multi-function digital pulse width modulation controller, including a pulse width modulation controller, a selection unit, a comparison unit, and a signal conversion unit, wherein the pulse width modulation controller generates a binary pulse wave The width modulation signal is used to drive the load circuit, and the two-digit pulse width modulation signal may have or have a blind band region, and the blind band region refers to a time segment when the two-digit pulse width modulation signal is simultaneously low. .

The selection unit includes at least one selector, the comparison unit includes at least one comparator, and the signal conversion unit includes at least one digit to analog converter. Each digit to analog converter receives a reference signal having a certain static level or variation and converts it to a corresponding reference voltage and/or reference current. Each comparator receives a reference voltage and/or a reference current and receives a specific feedback signal from the load circuit and performs a comparison process to generate a corresponding comparison signal, which is a digital signal having a low level or a high level. Each selector receives the above comparison signal and selects one of the comparison signals to be input to the pulse width modulation controller as a digital input signal. The pulse width modulation controller can simultaneously receive other parameters set by the user or the system to control the characteristics of the digital pulse width modulation signal, and can improve the overall electrical operation characteristics of the load circuit.

The embodiments of the present invention will be described in more detail below with reference to the drawings and the <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt;

Referring to the first figure, a schematic diagram of the multi-function digital pulse width modulation controller of the present invention. As shown in the first figure, the multi-function digital pulse width modulation controller of the present invention includes a pulse width modulation (PWM) controller 10, a selection unit 20, a comparison unit 30, and a signal conversion unit 40, wherein the PWM controller 10 Generating at least two digits of PWM signals, such as DPWM and nDPWM, for driving the load circuit 50, and the load circuit 50 includes two power transistors, such as a metal oxide half field effect transistor (MOSFET), for receiving the digital PWM signals DPWM and nDPWM, In order to achieve a single-ended output mode (Single-Ended Output Mode) or a push-pull output mode (Push-Pull Output Mode), and the single-ended output mode of the two-digit PWM signals DPWM and nDPWM do not have a dead zone (Dead Time Interval) The two-digit PWM signals DPWM and nDPWM in the push-pull output mode have a dead band. It should be noted that the blind band region of the present invention refers to a time segment in which the two-digit PWM signals DPWM and nDPWM are simultaneously low-level.

The PWM controller 10 can be implemented by an electronic circuit composed of a microcontroller (MCU), a central processing unit (CPU), or a plurality of electrical and electronic components, and operates in a digital manner.

The selection unit 20 includes at least one selector, such as SEL1 and SEL2, the comparison unit 30 includes at least one comparator, such as CP1, CP2, CP3, and CP4, and the signal conversion unit 40 includes at least one digit to analog converter (DAC), such as DAC1 and DAC2.

The digital to analog converters DAC1 and DAC2 of the signal conversion unit 40 respectively receive different two reference signals R1 and R2, and are respectively converted into corresponding reference voltages VREF1 and/or reference current IREF1, reference voltage VREF2 and/or reference current IREF2. Where reference signals R1 and R2 may be signals having a certain static level, For example, low level (logic 0) or high level (logic 1), or a changing signal, such as square wave or sine wave.

The comparators CP1, CP2, CP3, and CP4 of the comparison unit 30 receive the reference voltage VREF1, the reference current IREF1, the reference voltage VREF2, and the reference current IREF2 from the signal conversion unit 40, respectively, and receive the specific feedback signals from the load circuit 50, respectively. For example, at least one of a voltage feedback signal VFB1, a current feedback signal IFB1, a voltage feedback signal VFB2, and a current feedback signal IFB2, and performing a comparison process to generate a corresponding comparison signal, and each comparison signal has a low level. A quasi- or high-level digital signal.

The selectors SEL1 and SEL2 receive the comparison signal from the comparison unit 30, and select one of the comparison signals as an input signal to input to the PWM controller 10 according to the selection signal (not shown), wherein the selection signal can be set by the user or directly It is determined by the system.

In addition, the PWM controller 10 simultaneously receives other parameters set by the user or the system for controlling the characteristics of the digital PWM signals DPWM and nDPWM, such as the PWM period (T_PWM) shown in the second and third figures, and the working area. (T_Duty), blind band (T_DEAD), or PWM output mode (Output Mode), Soft Start Period, Run/Stop, Over Current Protection not shown in the figure. ), Shutdown.

Taking the setting of the above-mentioned blind band area (T_DEAD) as an example, it is mainly achieved by the PWM controller 10 changing the resolution of the digital PWM signals DPWM and nDPWM, that is, increasing the resolution to increase the working area size or reducing the resolution. The size of the work area is reduced, wherein the resolution refers to the minimum changeable unit of the work area, and the specific method of changing the number of resolutions is implemented by the PWM controller 10 according to the following four determination rules.

The first type of judgment rule includes: if the comparison unit 30 is in the previous PWM period The generated comparison signal is a logic N of consecutive N1 low levels, and the PWM controller 10 adds N2 resolutions to the working areas of the digital PWM signals DPWM and nDPWM in this cycle, wherein the parameters N1 and N2 are any positive integers, and may be User or system setting; and if the comparison signal is a continuous N1 high level logic 1 in the previous PWM period, the PWM controller 10 reduces the N2 resolution of the digital PWM signal DPWM and nDPWM in the PWM period. .

The second judging rule includes: if the high level of the comparison signal minus the low level in the previous PWM period is greater than the parameter N1, the working area of the digital PWM signal DPWM and nDPWM is reduced by N2 resolutions in this period. And if the low level of the comparison signal minus the high level is greater than the parameter N1 in the previous PWM period, then N2 resolutions are added to the working area of the digital PWM signals DPWM and nDPWM in the PWM period.

The third criterion includes: if the first two PWM periods are to increase the working area, the previous PWM period is to increase the working area N2 resolutions, and the PWM period is determined to increase the working area, the digital PWM signal DPWM in the PWM period and The working area of the nDPWM becomes increased (N2)*2, that is, doubled; and if the first two PWM periods are to reduce the working area, the previous PWM period is to reduce the working area by N2 resolutions and the PWM period is determined to be reduced. In the zone, the working area of the digital PWM signals DPWM and nDPWM in this cycle becomes reduced (N2)*2, that is, doubled.

The fourth judging rule includes: if the first two PWM periods are to increase the working area, the previous PWM period reduces the working area N2 resolutions, and the PWM period is determined to increase the working area, the digital PWM signals DPWM and nDPWM in the PWM period The working area becomes increasing (N2)/2, that is, halving the increase; and if the first two PWM periods are to reduce the working area, the previous PWM period is to increase the working area N2 resolutions and the PWM period is determined to be reduced. In the zone, the working area of the digital PWM signals DPWM and nDPWM in the PWM cycle becomes reduced (N2)/2, that is, reduced by half.

In summary, the present invention is characterized in that the number of resolutions of the working area in the current period can be dynamically changed according to whether the working area of the PWM signal in the previous PWM period is increased or decreased, thereby generating a PWM with optimized blind band area. A signal that drives the load circuit to improve the overall electrical operating characteristics of the load circuit.

The above is only a preferred embodiment for explaining the present invention, and is not intended to limit the present invention in any way, and any modifications or alterations to the present invention made in the spirit of the same invention. All should still be included in the scope of the intention of the present invention.

10‧‧‧PWM controller

20‧‧‧Selection unit

30‧‧‧Comparative unit

40‧‧‧Signal Conversion Unit

50‧‧‧Load circuit

CP1, CP2, CP3, CP4‧‧‧ comparator

DAC1, DAC2‧‧‧ digit to analog converter (DAC)

DPWM, nDPWM‧‧‧ digital PWM signal

IFB1, IFB2‧‧‧ current feedback signal

IREF1, IREF2‧‧‧ current reference signal

R1, R2‧‧‧ load signal

SEL1, SEL2‧‧‧ selector

T_Duty‧‧‧Workspace

T_DEAD‧‧‧Blind Zone

T_PWM‧‧‧PWM cycle

VFB1, VFB2‧‧‧ voltage feedback signal

VREF1, VREF2‧‧‧ voltage reference signal

The first figure shows a schematic diagram of the multi-function digital pulse width modulation controller of the present invention.

The second figure shows the waveform diagram of the PWM output in the present invention.

The third figure shows a waveform diagram of another PWM output in the present invention.

10‧‧‧PWM controller

20‧‧‧Selection unit

30‧‧‧Comparative unit

40‧‧‧Signal Conversion Unit

50‧‧‧Load circuit

CP1, CP2, CP3, CP4‧‧‧ comparator

DAC1, DAC2‧‧‧ digit to analog converter (DAC)

DPWM, nDPWM‧‧‧ digital PWM signal

IFB1, IFB2‧‧‧ current feedback signal

IREP1, IREF2‧‧‧ current reference signal

R1, R2‧‧‧ load signal

SEL1, SEL2‧‧‧ selector

VFB1, VFB2‧‧‧ voltage feedback signal

VREF1, VREF2‧‧‧ voltage reference signal

Claims (10)

A multi-function digital pulse width modulation controller for generating at least two digit Pulse Width Modulation (PWM) signals for driving a load circuit, the multi-function digital pulse width modulation controller comprising: a signal conversion a unit comprising at least one digit to analog converter, each digit to analog converter receiving a different reference signal and generating a corresponding reference voltage and/or reference current; a comparison unit comprising at least one comparator, each comparator Receiving a reference voltage and/or a reference current from a corresponding digit of the signal conversion unit to the analog converter, and performing a comparison process according to a feedback signal from the load circuit to generate a comparison signal having a low level or a high level; a selection unit, comprising at least one selector, receiving a selection signal and a comparison signal from the comparison unit, and each selector selects one of the comparison signals as an input signal according to the selection signal; and a pulse width modulation a variable (PWM) controller that receives input signals from the selection unit and/or by a user or system Determining a parameter, and controlling a number of resolutions of the working area of the digital pulse width modulation signal according to at least one determination rule, thereby changing a blind band area of the digital pulse width modulation signal, wherein the resolution It is the smallest variable amount unit of the working area, and the blind band area is a time section in which the digital pulse width modulation signals are simultaneously low level. The multi-function digital pulse width modulation controller according to claim 1, wherein the reference signal is a signal having a certain static level or a variable signal, and the static The state level includes a low level (logic 0) or a high level (logic 1), and the changed signal includes a square wave or a sine wave. The multi-function digital pulse width modulation controller according to claim 1, wherein the feedback signal of the load circuit includes at least a voltage feedback signal, a current feedback signal, a voltage feedback signal, and a current feedback signal. one. The multi-function digital pulse width modulation controller according to claim 1, wherein the selection signal is set by a user or directly determined by a system. The multi-function digital pulse width modulation controller according to claim 1, wherein the pulse width modulation controller is a microcontroller (MCU), a central processing unit (CPU) or a plurality of electrical and electronic components. It is realized by the constructed electronic circuit. The multi-function digital pulse width modulation controller according to claim 1, wherein the judging rule comprises: if the comparison signal generated by the comparison unit in the previous PWM period is a continuous N1 low level logic 0, Then, the PWM controller adds N2 resolutions to the working area of the digital PWM signal in the current cycle; and if the comparison signal is a continuous N1 high level logic 1 in the previous PWM period, the PWM controller is In this cycle, the working area of the digital PWM signal is reduced by N2 resolutions, and the parameters N1 and N2 are any positive integers, and are set by the user or the system. The multi-function digital pulse width modulation controller according to claim 1, wherein the judging rule comprises: if the number of times of the high level of the comparison signal minus the low level is greater than the parameter in the previous PWM period N1, the N2 resolution is reduced in the working area of the digital PWM signal in the current cycle; and if the number of times the low level of the comparison signal is subtracted from the high level in the previous PWM period is greater than the parameter N1, then In the current cycle, N2 resolutions are added to the working area of the digital PWM signal, and the parameters N1 and N2 are any positive integers, and are set by the user or the system. According to the multi-function digital pulse width modulation controller described in claim 1, wherein the judging rule includes: if the first two PWM periods are increasing the working area, the previous PWM period is increasing the working area N2 resolutions and The PWM period is determined to increase the working area, and the working area of the digital PWM signal in the PWM period becomes increased (N2)*2; and if the first two PWM periods are the reduced working area, the previous PWM period is the reduced working area. N2 resolutions and the PWM period is determined to reduce the working area, then the working areas of the digital PWM signals DPWM and nDPWM in the PWM period become reduced (N2)*2, and the parameters N1 and N2 are any positive Integer, set by the user or system. The multi-function digital pulse width modulation controller according to claim 1, wherein the determining rule comprises: if the first two PWM periods are increasing the working area, and reducing the working area of the previous PWM period N2 resolutions and the PWM period is determined to increase the working area, then the working area of the equal-digit PWM signal in the PWM period becomes increased (N2)/2; and if the first two PWM periods are reduced working area, the previous one The PWM period is to increase the working area N2 resolutions and the PWM period is determined to reduce the working area, then the working area of the digital PWM signals in the PWM period becomes reduced (N2)/2, and the parameters N1 and N2 Is any positive integer and is set by the user or system. The multi-function digital pulse width modulation controller according to claim 1, wherein the PWM controller further receives parameters set by a user or a system for controlling PWM period and PWM output of the digital PWM signals. Mode, Soft Start Period, Run/Stop, Over Current Protection, or Shutdown, and the PWM output mode includes the two-bit PWM signal without a dead band The single-ended output mode (Single-Ended Output Mode) and the two-digit PWM signal have a push-pull output mode (Push-Pull Output Mode).