TWI470915B - Boost converter and power factor controller - Google Patents

Description

Boost converter and power factor controller

The present invention is related to the field of power factor correction control, and more particularly to a boost converter and a power factor controller.

The statements in this section merely provide background information related to the present invention and may not constitute prior art.

The load may appear to the power supply as resistive impedance, inductive impedance, capacitive impedance, or a combination thereof. When the current flowing to the load is in phase with the voltage applied to the load, the power factor is close to one.

When the power factor is less than 1, the transmitted power may be wasted (due to phase mismatch between current and voltage) and/or noise may be introduced into the power line. To reduce noise and increase efficiency, power supplies typically use a power factor correction (PFC) circuit to control the phase of the current waveform relative to the phase of the voltage waveform.

Referring now to Figure 1, a conventional boost converter 10 includes a rectifier 15 that receives alternating current (AC) power. Before the input current I _in is supplied to the load 70 through the inductor 20 and input current I _in flowing through the portion of diode 50 (having a capacitor / filter 60 at its output).

The power factor controller 30 is responsive to the AC voltage sense input 12, the DC output voltage 72, the power conversion current sensed by the second inductor coil 25, and the feedback current via the node 34, and controls the flow through the inductor by turning the switch 40 on and off. 20 currents. When switch 40 is turned on, current 22 typically flows through inductor 20 (thereby storing some energy in inductor 20) It then flows through switch 40 to the ground. When switch 40 is turned off, current 52 can flow through diode 50 and some charge can collect on capacitor/filter 60. Typically, when switch 40 is turned off, current 22 flowing through inductor 20 is significantly reduced or even blocked.

Referring now to Figure 2, the AC voltage V received by boost converter 10 is shown. The input voltage V is a rectified half sine wave of the AC waveform input. However, due to the on/off period of the switch 40 (controlled by the power factor controller 30 in FIG. 1), the current waveform I in FIG. 2 has a sawtooth pattern. After the sawtooth waveform I passes through a low pass filter (eg, high frequency bypass capacitor/filter 60 in FIG. 1), the input current waveform is similar to the input AC voltage at the input of rectifier 15.

In most cases, especially where those load powers are high enough to allow a perceptible average input current to flow continuously through the inductor 20, the PF (power factor) used for the conversion is close to one. This mode is referred to as the "average current mode" or "continuous mode" of operation of boost converter 10.

The PFC of a boost converter typically has two parameters defined by the specification: (1) PF, and (2) total harmonic distortion (ie, THD). THD refers to distortion that is usually caused by higher order harmonics. For an AC signal of 60 Hertz (Hz), the higher order harmonics are at 120 Hz, 180 Hz, or other values of n x 60 Hz, where n is an integer greater than or equal to two. Generally, the higher the THD, the lower the efficiency. Harmonic distortion can saturate the inductance 20 in the boost converter 10. Also, if the THD is high enough, the noise may be fed back to the AC power lines 12-14, which is undesirable.

Referring now to Figure 3A, a low power and/or low voltage portion 120 of the voltage and current waveforms of Figure 2 is illustrated. The voltage waveform V is the voltage at the output of the rectifier 15 (see Figure 1). The current waveform I is the input current I _in flowing through the inductor 20. When the switch 40 in FIG. 1 at time t ₀ is turned on, a current I is a substantially linear manner is increased, the ramp 122 as shown. Switch 40 is turned on for a period of time determined by power factor controller 30. At the end of this time (point 124 of current waveform I in Figure 3A), switch 40 is turned off and current I is reduced in a substantially linear manner. The switch 40 is then turned on again by the power factor controller 30 after a period of time t _s - t ₀ that is also determined by the power factor controller 30 (see Figure 1).

When the current I = 0 (i.e., the current value I ₀ during the "zero current period" 126 in Figure 3A), the average current mode or continuous mode of operation has potential distortion problems. Since no current flows through the inductor 20 of FIG. 1, the THD cannot be controlled during the zero current period 126 of the waveform portion 120.

A discontinuous mode of operation of boost converter 10 occurs during a period of time during which switch 40 is turned "on" and "off" for a length of time sufficient for the zero current period to occur. When the current waveform I (see Fig. 3A) is zero or close to zero (I ₀ ), a critical mode of operation occurs. The desired inductor current I _in an amount greater than zero to maximize the time (see FIG. 1), and the zero current period is minimized (e.g., zero-current period in FIG. 3A 126).

Referring now to Figure 3B, ideally, t _s will occur at a point in time at which current I intersects I ₀ ("I = 0" axis), and zero current period 126 will have a duration as close as possible to 0 time units. , and the switch 40 (see FIG. 1) is turned in the current waveform portion 134 is substantially a power factor controller 30 (see FIG. 1) and I ₀ immediately after the crossing (see FIG. 3B). When this happens, the current waveform of a current waveform portion 136 and portion 134 rises immediately after crossing I _0, and the current flows through the inductor 20 is substantially continuous (see FIG. 1). Switch 40 should not be too early (i.e., the current waveform portion 134 of FIG. 3B before I ₀ Cross) is turned on. When this occurs, the average input current may increase at a too high rate, which may cause the input current waveform phase to deviate from the phase of the input voltage waveform.

One conventional method of detecting an input current flowing through the inductor 1 of FIG. 20 is I _in. A second inductor magnetically coupled to the inductive coil 20 through the inductor 25 to sense the current I _in 20. However, this method has a waiting time when sensing the current in the other coil. This wait time introduces some positive time length in the zero current period 126 (see Figure 3A) and introduces noise back into the AC power line 12-14. Moreover, the second inductive coil 25 adds some expense in manufacturing the power factor controller 30, and at least one dedicated differential pin is required on the power factor controller 30 to receive information from the second inductive coil 25.

Another approach attempts to sense the current at node 34 in FIG. However, the current and voltage values at node 34 are relatively low in the critical mode of operation. As a result, the error signal based on the measurement is relatively inaccurate. Moreover, determining the current at node 34 would require power factor controller 30 to have a relatively high sampling rate in the critical mode (ie, take samples that are much greater than 1 per 1/[ t _s - t ₀ ] seconds), and sample The resolution should be relatively high to avoid turning on the switch 40 too quickly or too slowly.

A boost converter includes an inductor that receives an input signal. The switch controls the current supplied to the load by the inductor. The power factor control module includes a mode control module that selects an operation mode of the boost converter; and a switch control module that switches the switch at a switching frequency. The switching frequency is equal to the first frequency when the mode control module selects the continuous mode, and is equal to the second frequency when the mode control module selects the discontinuous mode. The first frequency is greater than the second frequency.

In other features, the switch control module determines the switching frequency independently of the measurement of the current through the inductor. The power factor control module further includes: a phase detection module that determines a period of the input signal; a peak voltage determination module that senses a peak voltage of the input signal; and an on-time module that provides an on-time of the switch. The power factor control module also includes an off-time module that calculates the off time of the switch based on the period, the on time, and the peak voltage. The turn-off time module calculates the turn-off time independently of the measurement of the current flowing through the inductor. The phase detection module includes a zero crossing module that detects a zero crossing of the voltage of the input signal.

In other features, when the mode control module selects the continuous mode, the boost converter transitions from the discontinuous mode to the continuous mode based on the zero crossing. When the mode control module selects the discontinuous mode, the boost converter transitions from the continuous mode to the discontinuous mode based on the zero crossing. The phase detection module also determines the phase of the input signal. The first frequency is greater than the threshold frequency and the second frequency is less than the threshold frequency. The threshold frequency is based on the phase of the input signal.

In other features, the threshold frequency is based on: f _c = 0.25 × (V _p ² ) × (1 - V _p × sin(θ) / V _o ) / (P _o × L), where f _c is a threshold frequency, θ is the phase, Vp is the peak voltage of the input signal, V _o is the output voltage of the power converter, P _o is the output power of the power converter, and L is the inductance Value.

In other features, the threshold frequency is based on the peak value of the input signal, the output power of the boost converter, and the value of the inductance. The threshold frequency is the product of the maximum threshold frequency and the first value. The maximum threshold frequency is based on the peak voltage of the input signal, the output power of the boost converter, and the first inductance value of the inductor. The first value is based on the peak voltage and boost conversion of the input signal The output power of the device.

A power factor controller includes a mode control module that selects an operating mode of the power converter and a switch control module that switches the switch at a switching frequency to control the current supplied to the load by the inductor. The switching frequency is equal to the first frequency when the mode control module selects the continuous mode. The switching frequency is equal to the second frequency when the mode control module selects the discontinuous mode. The first frequency is greater than the second frequency. The switch control module determines the switching frequency independently of the measurement of the current through the inductor.

In other features, the phase detection module determines the period of the input signal. The peak voltage determination module senses the peak voltage of the input signal. The on-time module provides the on-time of the switch. The turn-off time module calculates the turn-off time of the switch based on the period, on-time, and peak voltage. The phase detection module includes a zero-crossing module that detects a zero crossing of the input signal voltage.

In other features, when the mode control module selects the continuous mode, the power converter transitions from the discontinuous mode to the continuous mode based on the zero crossing. When the mode control module selects the discontinuous mode, the power converter transitions from the continuous mode to the discontinuous mode based on the zero crossing.

In other features, the phase detection module determines the phase of the input signal. The first frequency is greater than the threshold frequency and the second frequency is less than the threshold frequency. The threshold frequency is based on the phase of the input signal.

In other features, the threshold frequency f _c is based on: f _c = 0.25 × (V _p ² ) × (1 - V _p × sin(θ) / V _o ) / (P _o × L) where f _c is The threshold frequency, θ is the phase, Vp is the peak voltage of the input signal, V _o is the output voltage of the power converter, P _o is the output power of the power converter, and L is The value of the inductance.

In other features, the threshold frequency is based on the peak value of the input signal, the output power of the power converter, and the value of the inductance. The threshold frequency is based on the maximum threshold frequency and the first value. The maximum threshold frequency is based on the peak voltage of the input signal, the output power of the power converter, and the first inductance of the inductor. The first value is based on the peak voltage of the input signal and the output power of the power converter.

A method for operating a boost converter includes: providing a switch that controls a current supplied to a load by an inductor; selecting an operating mode of the boost converter; switching the switch at a switching frequency; and operating in a continuous mode The switching frequency is set equal to the first frequency, and the switching frequency is set equal to the second frequency when operating in the discontinuous mode. The first frequency is greater than the second frequency.

In other features, the method further comprises determining the switching frequency independently of the measurement of the current through the inductor. The method also includes determining a period of the input signal, sensing a peak voltage of the input signal, and providing an on-time of the switch.

In other features, the method includes calculating a turn-off time of the switch based on a period, an on time, and a peak voltage. The turn-off time is calculated independently of the measurement of the current flowing through the inductor. The method includes detecting a zero crossing of a voltage of an input signal. When the continuous mode is selected, the boost converter transitions from the discontinuous mode to the continuous mode based on the zero crossing. When the discontinuous mode is selected, the boost converter transitions from the continuous mode to the discontinuous mode based on the zero crossing.

In other features, the method includes detecting a phase of the input signal. The first frequency is greater than the threshold frequency and the second frequency is less than the threshold frequency. The threshold frequency is based on the phase of the input signal. The threshold frequency is based on: f _c = 0.25 × (V _p ² ) × (1 - V _p × sin(θ) / V _o ) / (P _o × L) where f _c is the threshold frequency, θ is the phase, Vp is the peak voltage of the input signal, V _o is the output voltage of the power converter, P _o is the output power of the power converter, and L is the value of the inductance.

In other features, the threshold frequency is based on the peak value of the input signal, the output power of the boost converter, and the value of the inductance. The threshold frequency is the product of the maximum threshold frequency and the first value, wherein the maximum threshold frequency is based on the peak voltage of the input signal, the output power of the boost converter, and the first inductance value of the inductor. The first value is based on the peak voltage of the input signal and the output power of the boost converter.

A method for operating a power factor controller includes: selecting an operating mode of a power converter; switching a switch at a switching frequency to control a current supplied to the load by the inductor; and switching the frequency setting when the mode control module selects the continuous mode Is equal to the first frequency; and the switching frequency is set equal to the second frequency when the mode control module selects the discontinuous mode. The first frequency is greater than the second frequency. The switch control module determines the switching frequency independently of the measurement of the current through the inductor.

In other features, the method includes determining a period of the input signal; sensing a peak voltage of the input signal; and providing an on-time of the switch. The method also includes calculating a turn-off time of the switch based on the period, the on-time, and the peak voltage. The method includes detecting an input signal The zero crossing of the voltage.

In other features, when the continuous mode is selected, the power converter transitions from the discontinuous mode to the continuous mode based on the zero crossing. When the discontinuous mode is selected, the power converter transitions from the continuous mode to the discontinuous mode based on the zero crossing. In other features, the method includes detecting a phase of the input signal. The first frequency is greater than the threshold frequency and the second frequency is less than the threshold frequency. The threshold frequency is based on the phase of the input signal. The threshold frequency f _c is based on: f _c = 0.25 × (V _p ² ) × (1 - V _p × sin(θ) / V _o ) / (P _o × L), where f _c is the threshold Frequency, θ is the phase, Vp is the peak voltage of the input signal, _Vo is the output voltage of the power converter, P _o is the output power of the power converter, and L is the value of the inductor .

In other features, the threshold frequency is based on the peak value of the input signal, the output power of the power converter, and the value of the inductance. The threshold frequency is based on the maximum threshold frequency and the first value. The maximum threshold frequency is based on the peak voltage of the input signal, the output power of the power converter, and the first inductance value of the inductor. The first value is based on the peak voltage of the input signal and the output power of the power converter.

A boost converter includes: an inductive device for providing an inductor and for receiving an input signal; a switching device for controlling a current supplied to the load by the inductor; and a power factor control device for controlling a power factor of the boost converter The boost converter includes a mode control device for selecting an operation mode of the boost converter, and a switch control device for setting a switching frequency of the switching device when the mode control device selects the continuous mode Is equal to the first frequency and the discontinuity in the mode control device selection In the mode, the switching frequency of the switching device is set equal to the second frequency. The first frequency is greater than the second frequency.

In other features, the switch control device determines the switching frequency independently of the measurement of the current through the inductive device. The power factor control apparatus further includes: phase detecting means for determining a period of the input signal, peak voltage determining means for sensing a peak voltage of the input signal, and on-time means for providing an on-time of the switching means.

In other features, the power factor control device further includes an off time device for calculating an off time of the switching device based on the period, the on time, and the peak voltage. The turn-off time device calculates the turn-off time independently of the measurement of the current flowing through the inductive device. The phase detecting device includes a zero crossing device that detects a zero crossing of the voltage of the input signal.

In other features, when the mode control device selects the continuous mode, the boost converter transitions from the discontinuous mode to the continuous mode based on the zero crossing. When the mode control device selects the discontinuous mode, the boost converter transitions from the continuous mode to the discontinuous mode based on the zero crossing.

In other features, the phase detecting device also determines the phase of the input signal. The first frequency is greater than the threshold frequency and the second frequency is less than the threshold frequency. The threshold frequency is based on the phase of the input signal.

In other features, the threshold frequency is based on: f _c = 0.25 × (V _p ² ) × (1 - V _p × sin(θ) / V _o ) / (P _o × L), where f _c is a threshold frequency, θ is the phase, Vp is the peak voltage of the input signal, V _o is the output voltage of the power converter, P _o is the output power of the power converter, and L is the inductance The value of the device.

In other features, the threshold frequency is based on the peak value of the input signal, the output power of the boost converter, and the value of the inductive device. The threshold frequency is the product of the maximum threshold frequency and the first value. The maximum threshold frequency is based on the peak voltage of the input signal, the output power of the boost converter, and the first inductance of the inductive device. The first value is based on the peak voltage of the input signal and the output power of the boost converter.

A power factor controller includes: a mode control device for selecting an operation mode of the power converter; and a switch control device that switches the switch at a switching frequency to control a current supplied to the load by the inductor. The switch control device sets the switching frequency to be equal to the first frequency when the mode control device selects the continuous mode, and sets the switching frequency to be equal to the second frequency when the mode control device selects the discontinuous mode. The first frequency is greater than the second frequency. The switching control device determines the switching frequency independently of the measurement of the current through the inductor.

In other features, the phase detecting means determines the period of the input signal. The peak voltage determining means senses the peak voltage of the input signal. The on-time device provides the on-time of the switching device. The off time calculation means calculates the off time of the switching device based on the period, the on time, and the peak voltage.

In other features, the phase detecting device includes a zero crossing device for detecting a zero crossing of the voltage of the input signal. When the mode control device selects the continuous mode, the boost converter transitions from the discontinuous mode to the continuous mode based on the zero crossing. When the mode control device selects the discontinuous mode, the boost converter switches from the continuous mode based on the zero crossing Change to discontinuous mode. The phase detecting means determines the phase of the input signal. The first frequency is greater than the threshold frequency and the second frequency is less than the threshold frequency. The threshold frequency is based on the phase of the input signal.

In other features, the threshold frequency f _c is based on: f _c = 0.25 × (V _p ² ) × (1 - V _p × sin(θ) / V _o ) / (P _o × L) where f _c is The threshold frequency, θ is the phase, Vp is the peak voltage of the input signal, V _o is the output voltage of the power converter, P _o is the output power of the power converter, and L is The value of the inductance.

In other features, the threshold frequency is based on the peak value of the input signal, the output power of the power converter, and the value of the inductance. The threshold frequency is based on the maximum threshold frequency and the first value. The maximum threshold frequency is based on the peak voltage of the input signal, the output power of the power converter, and the first inductance of the inductor. The first value is based on the peak voltage of the input signal and the output power of the power converter.

The description provided here can be seen in other areas of application. It should be understood that the description and specific examples are not intended to

Reference will now be made in detail to the preferred embodiments of the invention While the invention will be described in conjunction with the preferred embodiments, it is understood that the invention Rather, the invention is intended to cover alternatives, modifications, and equivalents of the embodiments of the invention. In addition, in the following detailed description of the invention, numerous specific details However, those skilled in the art will readily appreciate that these specific details can be The present invention is implemented in the context of the section. In other instances, well-known methods, procedures, components, and circuits are not described in detail to avoid unnecessarily obscuring aspects of the present invention.

Portions of the detailed description that follows are presented in terms of processes, processes, logic blocks, functional blocks, and other symbol representations that operate on data bits, data flows, or waveforms in a computer, processor, controller, and/or memory. These descriptions and representations are generally used by those skilled in the data processing arts to convey the substance of their work to those skilled in the art. Processing, processes, logic blocks, functions, operations, etc. are generally considered to be a self-consistent sequence of steps or instructions leading to the desired and/or expected results. These steps typically involve physical manipulation of physical quantities. Usually, though not necessarily, these quantities take the form of an electrical, magnetic, optical or quantum signal capable of being stored, transferred, combined, compared, and otherwise manipulated in a computer, data processing system or logic. It has proven convenient at times, principally for public purposes, to designate these signals as bits, waves, waveforms, streams, values, elements, symbols, characters, terms, numbers, and the like.

However, it should be borne in mind that all of these and similar terms are associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless otherwise stated and/or apparent from the following discussion, it will be appreciated that throughout the application, such as "processing," "operation," "calculation," "determining," "manipulating," The terms "transformation", "display", and the like refer to the actions and processing of computers, data processing systems, logic circuits, or similar processing devices (eg, electrical, optical, or quantum computing or processing devices) that are represented as physical ( For example, electronic data is manipulated and transformed. These terms refer to the actions, operations, and/or processing of processing devices that are stored in the system or architecture(s) (eg, registers, memory, other such information storage, transmission The physical quantities in the input or display device, etc., are manipulated or otherwise transformed into other materials that are similarly represented as physical quantities in other components of the same or different systems or architectures.

In addition, for convenience and simplicity, the terms "data", "data flow", "waveform" and "information" are generally used interchangeably herein, but generally they are assigned to identify domain meanings. Moreover, for convenience and simplicity, the terms "connected to", "coupled to", "coupled to", and "communicated with" may be used interchangeably (these terms may also refer to The direct and/or indirect relationship between the connected, coupled, and/or communication elements, unless the context of use of the term clearly indicates otherwise, is also generally given to the context in which they are identified. The term "module," "circuit," and/or "device" as used herein, refers to a dedicated integrated circuit (ASIC), an electronic circuit, a processor that executes one or more software or firmware programs (shared processor, dedicated processing). And a processor group) and memory, combinational logic, and/or other suitable components that provide the described functionality. The phrase "at least one of A, B, and C" as used herein should be interpreted to mean a logic (A or B or C) that uses a non-exclusive logical "or".

The present invention relates to circuits, systems, methods and software for power factor correction and/or control. The present invention typically takes a computational approach to reduce and/or minimize the zero current period in the critical mode of boost converter operation. An inventive circuit is a power factor controller comprising (a) a period configured to determine and/or identify (i) a periodic power signal and (ii) a time from the beginning of a period at which the potential is applied to the power transfer switch a length of circuit; (b) a voltage calculator configured to determine at least a peak voltage of the periodic power signal; and (c) configured to respond to (i) length of time, (ii) power signal period, and (iii) peak value The voltage is used to calculate the logic of the time period during which the switch is turned on. The system generally includes the invention A power factor controller and a switch it controls, but another aspect of the system relates to a power converter including such a system and an inductor or other device for storing periodicity from, for example, an AC power signal The energy of the power signal.

Another aspect of the invention relates to a method of correcting and/or controlling power factor and/or controlling power conversion. The method generally includes (1) responsive to applying a potential to a switch in electrical communication with the power converter to store energy from the periodic power signal in the power converter; (2) calculating a time period for opening the switch based on the following parameters: (i) an initial length of time during which a potential is applied to the switch, (ii) a period of the periodic power signal, and (iii) a peak voltage of the periodic power signal; and (3) the switch is turned on during the time period. The software includes a set of instructions that are readable or executable by a processor that is configured to implement the methods of the present invention and/or any process or sequence of steps embodied in the inventive concepts described herein.

Various aspects of the invention are described in more detail below with respect to exemplary embodiments.

Exemplary boost converter

In one aspect, the present invention is directed to a power converter including a power factor controller of the present invention (described in more detail below), an inductor configured to store energy from a periodic power signal, and a power transfer switch, the power The transfer switch is configured to charge the inductance when a potential is applied to the switch. Typically, the switch is controlled by the power factor controller of the present invention and the periodic power signal is an alternating current (AC) power signal or a rectified AC power signal. In one implementation, the power converter is an AC-DC boost converter.

In various embodiments, the power converter may further include a diode, a ripple filter, and/or a rectifier, wherein the diode is configured to receive the input from the inductor The output voltage is supplied to the load, the chopper filter is coupled to the output of the diode, and the rectifier is configured to rectify the AC power signal. In one embodiment, the periodic power signal includes the output of the rectifier (eg, it is a rectified AC power signal).

In other embodiments, the inductance converts a periodic power signal (eg, an AC signal) into a substantially constant power signal (eg, a DC signal); and/or the switch can be configured to (i) when a voltage is applied to the switch The power conversion current is supplied to the inductor (eg, when the switch is closed) and/or (ii) the power conversion current flowing through the inductor is reduced, eliminated, or blocked when the switch is turned on.

The operation of the power factor controller and power converter of the present invention will best be described with reference to the exemplary embodiments. 4 shows a first exemplary embodiment of a boost converter 200 that includes a four-way rectifier 210, an inductor 220, an exemplary power factor controller 230, and a switch 240, four The circuit rectifier 210 receives the AC power source AC from the power lines 212 and 214. Boost converter 200 may also include current feedback resistor 235, diode 250, and capacitor/filter 260, and node 272 coupled to capacitor/filter 260 may also be in communication with load 270. Similar to the conventional power factor controller 30 of FIG. 1, the power factor controller 230 of FIG. 4 effectively turns on and off the switch 240 by responding to the AC power line 212, the DC output voltage 272, and the feedback current node 234 to turn the switch 240 on and off. The current of the inductor 220. However, the power factor controller 230 of the present invention calculates the length of time that the switch 240 remains off to reduce or minimize the zero current period, and does not require a second inductance to sense when the input current through the inductor 220 is zero.

For example, in FIG. 4, when switch 240 is turned on, current typically flows through inductor 220, thereby storing some energy in inductor 220. When switch 240 is turned off, current can flow through The diode 250 and some of the charge can collect in the capacitor/filter 260, but typically, the current flowing through the inductor 220 is severely reduced or blocked. The diode 250 is thus configured to (i) receive the output from the inductor 220 and (ii) pass the current from the output of the inductor unidirectionally to become a substantially constant output voltage (typically applied to the load 270).

An object of the present invention is calculated so that the operation or zero current through the switch length ( "t _off") 240 of the inductor 220 off time. If it is possible to calculate or calculate (" t _off "), it can be determined when the switch 240 is switched back to the conducting state in a manner that minimizes the zero current period. The present invention focuses primarily on power factor controllers that are configured to perform such calculations.

FIG. 5 shows current and voltage waveforms of the boost converter 200 of FIG. 4 in a critical current mode of operation. At time t ₀ the switch 240 is turned on, so the current I 220 flowing through the inductor in a substantially linear rate increases (e.g., see Figure 5 in the current waveform portion 310). The switch 240 remains conductive for a predetermined length of time t _on , wherein the predetermined length of time can be programmed into the memory unit of the power factor controller 230 (see FIG. 4), or conventionally responded to by the power factor controller 230 by one or more a conventional input (e.g., current or voltage input from the AC power line 212, the output voltage V _out from the node 272 and / or feedback current feedback node of the power converter 234, etc.) are calculated, calculation or determination. After the time t _on, the power factor controller 230 turns off the switch 240, and current waveform I is a substantially linear rate until the drop until the current I = 0 (e.g., see Figure 5 in the current waveform portion 320). The length of time t _off at which switch 240 is turned off so that current I reaches zero can be calculated or calculated according to a plurality of known parameters using a relatively simple triangulation technique, including t _on , AC _on AC power line 212 peak AC input voltage and the output voltage V _out input voltage V _p and the node 272. The design and use are configured to clearly within the purview of one skilled in the art, one skilled in the art may be apparent from the following discussion that point t _off according to the logic of the operations or calculations of these parameters are known.

The triangulation method of determining t _off is relatively straightforward. Referring to FIG. 5, the slope of the rising current waveform portion 310 is simply the voltage V _in of the node 216 divided by the inductance L of the inductor 220. Similarly, the slope of the decline in current waveform portion 320 is simply the output voltage V _out (at node 272) minus V _in (node 216) obtained by dividing the difference value L. Current waveform portions 310 and 320 are each formed of two right-angled triangle the hypotenuse of which is at time t _on the abscissa by the inductor 220 current I _in, and the ordinate, respectively t _on and t _off. Based on these relationships, t _off can be calculated. Mathematically, the slope (310) = V _in / L [1]

Slope (320) = (V _out - V _in ) / L [2]

t _off = t _on ×V _in /(V _out -V _in ) [3] The output voltage V _{out is} generally predetermined and/or known by design; for example, V _out has a specified, substantially constant value (eg 450V) , although due to the small ripple and some minor fluctuations in the actual value, (s) a small ripple sources are known to the skilled person, but as a percentage _of V _out is small and / or ignorable. Therefore, in order to calculate t _off , V _out is generally considered to be a constant value. However, in one embodiment, to determine V _out (e.g., measured or samples) every n turns on the switch 240 on / off cycle at where n is an integer, and V _out the value by the calculated t need _off or It is stored and/or updated in power factor controller 230 as required. In the case of certain applications of the present invention desired values V _out is observed, the relatively low resolution can be used to relatively accurately measure V _out (at least in the critical mode is detected at 220 or the inductor current feedback at node 234 Compared to the typical values of I _in and / or V _in ).

Further, as described above, t _on is known calculation and / or a predetermined value for t _off. However, node 216 need not be at the voltage V _in at a given time to a known point, or a predetermined fixed value during the critical operation mode converter. Instead, V _in can be calculated using known, (predetermined), fixed or reliably measurable and/or detectable parameter values. The rectified voltage at node 216 is still a half sine wave with a standard triangular relationship with other parameters. Thus, if the peak voltage V _p are known at the node 216 and the half cycle of the sine wave, it can calculate the value of V _in. Mathematically, V _in = V _p × sin(π t/T) [4] where t = t _on plus time 330 from t ₀ to t _on , and T is the period of the rectified voltage half sine wave (eg For a 60 Hz AC power signal, the period T is 1/(2 x 60 Hz) = 8.3 ms). In one embodiment, power factor controller 230 includes one or more counters that are configured to (i) count the length of period T and/or indicate the end of period T, and/or (ii) determine the time length t (e.g., in response to "the end of a period T" indicates to initialize a count of the known time increment, and when the switch 240 is turned off, the terminal count at the end of t _on).

As noted above, it is generally undesirable to turn on the switch 240 prematurely in the critical mode. However, when V _out fluctuations (e.g., due to the small ripple) and / or when the value of t is not determined, the switch 240 may be turned on earlier. As a result, referring now to FIG. 6, a small amount of time Δt can be added to _toff to provide a buffer to prevent the switch 240 from being turned on prematurely. Therefore, the time t _s at which the switch 240 is turned on for the second time in the critical mode may be equal to t _on +t _off +Δt. Alternatively, the angle (see FIG. 4), wherein t _off is the power factor controller 230 of switch 240 at a given on / off cycle the actual length in the OFF _{state, t off = [t on ×} V in / (V _out -V _in )]+△t [5]

In one embodiment, the transition between the average current mode of operation and the critical mode can be determined mathematically. Referring now to the graph in Fig. 7, two transition periods are shown, each of which is on one side of the end of the voltage half sine wave period T. The time period τ shown in Figure 7 is effectively half the cycle time of the boost converter 200 in the critical mode. Since the voltage half sine wave and the current waveform I are symmetrical about time = T axis, the critical mode time is effectively 2 × τ. The boost converter 200 is in an average current mode outside of the time from (T-τ) to (T+τ).

When the boost converter 200 is in the critical mode, the current waveform I crosses the I ₀ axis. As a result, t _s (which in this embodiment is the on/off period of switch 240; see Figure 4) needs to be longer than t _on +t _off (where t _off is the current waveform when switch 240 is turned off) The time it takes for I to reach I ₀ ). Mathematically, referring again to Figure 6, when (t _on + t _off ) < t _s , the boost converter 200 is in the critical mode. Conversely, when (t _on + t _off ) > t _s , the boost converter 200 is in the average current mode.

Exemplary power factor controller

A primary aspect of the invention relates to a power factor controller comprising (a) a circuit configured to identify (i) a period of a periodic power signal, and (ii) from a potential applied to a power conversion a length of time from the beginning of the cycle of the switch (eg, t _on ); (b) a voltage calculator configured to determine at least a peak voltage of the periodic power signal; and (c) logic configured to be configured The time period during which the switch is turned on is calculated in response to (i) length of time, (ii) power signal period, and (iii) peak voltage. Thus, the power factor controller of the present invention identifies (i) the power signal period and (ii) the length of time that the power transfer switch charges the power converter, determines the peak voltage of the periodic power signal, and responds to (1) the switch " The "time", (2) power signal period, and (3) peak voltage are used to calculate the time period during which the power transfer switch is turned off. In the context of the power factor controller of the present invention, the term "identifying" may mean receiving and/or providing a predetermined value for a power signal period and/or a length of time t _on , calculating or computing these based on one or more other parameter values. Value, or using traditional techniques for accomplishing such purposes (eg, counting from a known initial point or starting point to a known end or termination point, counting time increments of a predetermined or known length) Determine these values. Typically, the periodic power signal includes an AC power signal or a rectified AC power signal.

In various embodiments, the power factor controller of the present invention may further comprise (a) a voltage detector configured to determine a zero voltage at an input of the power converter; (b) one or more counters configured to respond Initiating a count of (i) a power signal period and/or (ii) a length of time from a signal indicative of zero voltage from a voltage detector; (c) a comparator configured to compare the power signal voltage to the first reference voltage and Providing a voltage calculator with a first relative voltage value; (d) a filter configured to reduce or remove harmonic noise from an output of the power converter (eg, from an output voltage feedback signal); and/or (e A filter configured to reduce or remove noise from the current feedback signal.

In other embodiments, the logic includes a digital signal processor, and/or the logic is further configured to calculate a time period(s) when the power converter including the switch is in a critical mode, or when the power converter includes the switch Applying a voltage to the switch for a predetermined period of time while in the critical mode. Therefore, the power factor controller of the present invention can process one or more A digital signal (usually a plurality of such signals, which will be described in more detail with reference to Figure 8). As a result, the power factor controller of the present invention may also include one or more (typically a plurality of) analog-to-digital (A/D) converters configured to convert analog signals input to the power factor controller Converted to a multi-bit digital signal to be processed by the power factor controller logic/digital signal processor. As is known in the art, the number of bits in an A/D converter corresponds to its resolution; the larger the number of bits, the higher the resolution (and wafer area, required processing power, and power factor control). The cost of the device is larger).

FIG. 8 shows an exemplary power factor controller 400 in accordance with the present invention. The power factor controller 400 generally includes a comparator block 410, a zero voltage cross locator 412, a voltage calculator 414, input A/D converters 420 and 430, filters 425 and 435, and digital signal processing including a critical mode controller 416. 440, an output digital analog (D/A) converter 445, and an output driver 450, the output driver 450 sends a control signal to turn the power transfer switch 240 on or off (and, if the switch 240 is to be closed, apply a certain potential to the switch 240) ). The present invention focuses primarily on critical mode controller 416 and its inputs.

Comparator block 410 receives a periodic (AC) power signal from AC power line 212. Given the known relationship between the signal from the AC power line 212 and its rectified signal (eg, the rectified AC power signal 216 in FIG. 4), those skilled in the art can readily follow the AC. Power line 212 performs the above calculations while avoiding any latency that rectifier 210 may introduce to the power conversion process. The comparator block 410 can include a comparator block having two or more comparators, wherein the first and second individual comparators compare the voltage on the AC power line 212 with the first and second reference voltages, respectively The one and second reference voltages are different from each other.

In one implementation, the first comparator in comparator block 410 compares the voltage on AC power line 212 to a reference voltage of zero volt (0V) and then provides comparison output 411 to zero voltage cross locator 412. The zero voltage cross locator 412 sends appropriate information and/or control signals to the critical mode controller 416 in response to the comparison. The output 411 of the first comparator can be analog or digital, but the output 413 of the zero voltage cross locator 412 is typically digital. It is apparent that the logic for designing and implementing these functions is within the abilities of those skilled in the art. For example, when output 411 is analogous, zero voltage cross locator 412 typically includes an A/D converter and output 413 is a multi-bit digital signal carrying information relating to the value of the voltage on AC power line 412 with respect to 0V. . However, when the output 411 is digital (ie, the first comparator identifies when the AC voltage 212 is 0V or not 0V), the zero voltage cross locator 412 typically includes control logic and the output 413 is a single or multi-bit digital signal, The digital signal is configured to instruct various circuits and/or logic in critical mode controller 416 to perform (or stop executing) one or more functions in response to AC voltage 212 being at 0V.

In another implementation, the second comparator in comparator block 410 is a conventional peak detector configured to determine AC power line 212 on a cycle-by-cycle basis (eg, an AC power signal period or a rectified AC signal half-cycle). The upper maximum voltage is then provided to the voltage calculator 414 for output 415, which in response to the peak detector output 415 sends the appropriate information and/or control signals to the critical mode controller 416. The output 415 of the second comparator can be analog or digital, but the output 417 of the voltage calculator 414 is typically digital. It is apparent that the logic for designing and implementing these functions is within the abilities of those skilled in the art. For example, when output 415 is analogous, voltage calculator 414 is typically An A/D converter is included and output 417 is a multi-bit digital signal carrying information related to the value of the peak voltage on AC power line 212. However, when the output 415 is digital (ie, the second comparator compares the voltage of the AC power line 212 with a plurality of reference voltages and provides a multi-bit digital output that identifies the voltage range over which the peak voltage is located), the voltage calculator 414 typically includes control logic and output 417 is a single or multi-bit digital signal that is configured to indicate that various circuits and/or logic in critical mode controller 416 are responsive to changes in peak AC voltage on AC power line 212. Adjust, execute, or stop performing one or more functions.

The critical mode controller 416 is configured to calculate or calculate at least two of: calculating a power signal input voltage (eg, V _in ) based on a peak voltage (V _p ) and a length of time (t _on ) at which the switch 240 is turned on in the critical mode; and 240 during which the turn-off time period when (and / or 240 in electrical communication otherwise the switch) when includes an inductor 220 of the power converter is in a critical mode, according to V _in, V _out, and t _on is calculated switch (e.g. The above t _off ).

Thus, critical mode controller 416 is generally configured to calculate V _in according to the following: peak AC voltage on AC power line 212 (provided by output 417 of voltage calculator 414), half cycle of AC power signal (equivalent to rectification) The period of the subsequent AC power signal is equal to the time difference between the points when the voltage on the AC power line 212 is at voltage = 0V, and is the information provided by the output 413 of the zero voltage cross locator 412), and from the AC power line 212. The time period from the AC voltage = 0V to the end of t _on . As noted above, t _on is a predetermined length of time that can be programmed into a memory unit in digital signal processor 440 (or elsewhere in controller 440) or traditionally can be responded to by digital signal processor 440. to one or more suitable input (e.g., current or voltage input from the AC power line 212, the output voltage V _out from the node 272 and / or a current feedback node of the power converter 234 feedback, etc.) to be calculated, the arithmetic Or OK.

Digital signal processor 440 also receives (1) a filtered multi-bit digital signal from filter 425 corresponding to the power converter output voltage feedback signal at node 272, and (2) corresponding to feedback current node 234. Filtered multi-bit digital signal from filter 435. Filter 425 can be a notch filter. These circuit blocks and signals are conventional and typically perform their traditional function(s). However, an unexpected advantage of the present invention is that A/D converters 420 and 430 (especially 430) can have lower resolution than corresponding A/D converters in conventional boost converters. This is generally because the method of calculation for t _off is minimized invention does not depend on V _out output from the DC current node 234 or reserved for those attempting to accurately measure the periodic zero current flowing through the inductor 220 of the high resolution information. As also described above, the buffering period Δt can be added to t _off to partially accommodate or allow small potential precision errors in measuring certain parameters, such as V _p , V _out , t, T, and/or (when needed or desired) t _on .

The digital signal processor 440 outputs a multi-bit digital signal to the D/A converter 445, which converts the multi-bit digital signal into an analog signal that instructs the output driver 450 to open or close the switch 240. If switch 240 is to be closed, the analog signal received by driver 450 informs driver 450 what potential to apply to the gate of switch 240. Alternatively, the output driver 450 can include a plurality of parallel driver circuits, each of which receives a bit of a multi-bit digital signal output by the digital signal processor 440, thereby avoiding the need for the D/A converter 445.

Exemplary method

The invention further relates to a method of controlling a power converter, the method comprising the steps of: (a) storing energy from a periodic power signal in a power converter in response to applying a potential to a switch in electrical communication with the power converter; b) calculating the time period (eg, t _off ) at which the switch is turned on according to the following parameters: (i) the initial time length at which the potential is applied to the switch (eg, t _on ), (ii) the period of the periodic power signal (eg, T), and (iii) the peak voltage (e.g., V _p) a periodic power signal; and (c) opening the switch during the time period. With regard to the above description of the hardware, the periodic power signal may include an AC power signal or a rectified AC power signal, depending on design choices and/or considerations. The energy is typically stored in the inductor when current from the rectified AC power signal flows through the inductor, and the current typically flows through the inductor when the switch is closed. When the switch is turned on, energy is typically not stored in the boost converter (inductor).

In various embodiments, the method may further comprise the steps of (1) determining a zero voltage at an input of the power converter; (2) responding to the zero voltage indication to (i) the power signal Cycle and/or (ii) length of time to time, identify or determine; (3) determine the peak voltage of the periodic power signal; (4) calculate the time period when the power converter is in critical mode or otherwise identify the power converter When in critical mode; (5) filtering out harmonic noise from the output of the power converter; and/or (6) filtering out noise from the current feedback signal. Each of these additional steps is typically performed as described above using a corresponding hardware configured to execute, implement or implement the steps.

In some embodiments, the step of determining a peak voltage can include comparing a voltage of the periodic power signal with a first reference voltage, sampling an output of the comparing step to generate a plurality of power signal voltage samples, and determining a maximum power signal voltage Sampled value, where the peak The voltage corresponds to the maximum power signal voltage sample value. Moreover, the method of the present invention generally further includes the step of applying a potential to the switch for a predetermined period of time when the power converter is in the critical mode.

Exemplary software

The present invention also includes an algorithm and/or computer program(s) and/or software executable and/or executable in a general purpose computer or workstation provided with a conventional digital signal processor, configured to perform the method. One or more steps and/or hardware one or more operations. Accordingly, another aspect of the invention relates to algorithms and/or software implementing the method(s) described above. For example, the invention may also relate to a computer program, computer readable medium or waveform comprising a set of instructions that are processed by a suitable processing device (eg, a signal such as a microcontroller, microprocessor or DSP device) The device) is configured to perform the above methods and/or algorithms when executed.

For example, the computer program can be on any kind of readable medium, and the computer readable medium can include any medium that can be read by the processing device, the processing device being configured to read the medium and execute code stored thereon or therein The medium is, for example, a floppy disk, a CD-ROM, a tape or a hard disk drive. Such code may include object code, source code, and/or binary code.

The waveform is typically configured for transmission over a suitable medium such as copper wire, conventional twisted pair wiring, conventional network cable, conventional optical data transmission cable, or even air for wireless signal transmission. Or vacuum (for example, outer space). The waveforms and/or codes used to implement the method(s) of the present invention are typically digital and are typically configured for use by conventional digital data processors (eg, microprocessors, micro-controls) Or logic circuits, such as programmable gate arrays, programmable logic circuits/devices, or dedicated [integrated] circuits.

In various embodiments, the computer readable medium or waveform includes at least one instruction (or a subset of instructions) to (a) respond to (i) the power signal period and/or in response to an indication of zero voltage on the periodic power signal. Or (ii) a predetermined number of time units corresponding to the length of time; (b) determining (eg, computing or calculating) a peak voltage; and/or (c) determining and/or indicating (eg, by calculating a corresponding time period) power When is the converter in critical mode? In one implementation, the instruction(s) determining the peak voltage includes at least one subset of instructions for: (i) sampling the output of the comparison of the periodic power signal voltage and the reference voltage, ( Ii) storing a plurality of power signal voltage samples, and (iii) determining a maximum power signal voltage sample value, wherein the peak voltage corresponds to the maximum power signal voltage sample value.

Accordingly, the present invention provides a circuit, system, method and software for controlling power conversion and/or correcting and/or controlling power factor in such conversion(s). The circuit typically includes a power factor controller including (a) a circuit configured to determine and/or identify (i) a period of the periodic power signal and (ii) a potential applied to the power conversion switch The length of time from the start of the cycle; (b) a voltage calculator configured to determine at least a peak voltage of the periodic power signal; and (c) configured to respond to (i) the length of time, (ii) The power signal period and (iii) the peak voltage are used to calculate the time period during which the switch is turned on. The system typically includes the power factor controller and its controlled switches, but the system aspect of the invention also relates to a power converter including the power factor controller, switches and inductors configured to store from periodic power The energy of the signal.

The method generally includes the steps of: (1) storing energy from a periodic power signal in a power converter in response to applying a potential to a switch in electrical communication with the power converter; (2) calculating a time to open the switch based on the following parameters Segment: (i) the initial length of time that the potential is applied to the switch, (ii) the period of the periodic power signal, and (iii) the peak voltage of the periodic power signal; and (3) the switch is turned on during the time period. The software typically includes a set of instructions suitable for performing the method.

The present invention generally employs a computational method to reduce and/or minimize zero current periods in a critical mode of power conversion operation, and advantageously reduce the zero current period in the critical mode to a reasonable and/or tolerable The minimum, thereby maximizing the power factor of the power converter in the critical mode and reducing the noise that may be injected back into the AC power line. The power factor controller of the present invention allows for greater design flexibility, reduced design complexity, and/or reduced resolution and/or greater margin of error in certain parameter measurements or samples.

Referring now to Figure 9, an alternative power factor control module 500 switches the mode of the boost converter. In some implementations, the power factor control module 500 can switch modes from a continuous mode to a discontinuous mode and/or from a discontinuous mode to a continuous mode during a zero crossing of the power line input signal.

The power factor control module 500 includes a phase detection module 504 that determines the phase θ of the input signal. Phase detection module 504 can include a zero crossing module 508 that detects zero crossings of the input signal voltage. Phase detection module 504 can determine the phase θ of the input signal based on the zero crossing. In other words, when a zero crossing occurs, the phase θ of the input signal can be 0° or 180°. It is also possible to determine the phase of the input signal based on the peak voltage of the input signal. θ, the peak voltage can appear at 90° and 270°.

Similarly, the period T of the input signal can be determined by the phase detection module 504. In other words, half of the period T of the input signal can be equal to the period between two zero crossings or between two peak voltages. Alternatively, the period T can be set to a constant value if the period T is known.

The power factor control module 500 can also include a peak voltage determination module 512 that determines the peak voltage of the input signal. Peak voltage determination module 512 can sample and maintain the input voltage to identify the peak voltage. In other words, the sample hold continues until the sample value has decreased relative to the previous value. Other techniques can be used to identify the timing and/or amplitude of the peak voltage. Peak voltage determining module 512 outputs a peak voltage V _p to the phase detector module may be 504 to indicate the estimated phase θ of the input signal.

The power factor control module 500 can also include a switch control module 516 that controls the state of the switch and the switching frequency of the switch. The phase detection module 504 can output the period T, the phase θ, and/or the zero-crossing signal of the power line input signal to the switch control module 516. Peak voltage determination module 512 may be a signal such as a peak voltage amplitude of the power line input signal V _p and / or timing to the switch control module 516.

The switch control module 516 can also include a mode control module 520 that selects the mode of the boost converter. For example, the mode can be set to continuous mode, discontinuous mode, or critical mode. The mode control module 520 can also be disposed external to the switch control module 516 and/or coupled to another module of the power factor control module 500.

The mode control module 520 can select a mode based on the sensed operational parameters and determine whether to switch modes. For example only, the mode control module 520 may determine when to switch the mode from the continuous mode to the discontinuous mode or from the discontinuous mode based on the zero crossing signal. Switch to continuous mode. For example only, switching may be performed within a predetermined time period of the power line zero crossing. However, switching between modes can also occur at different phase positions of the power line input signal (except for switching at the zero crossing of the power line input signal voltage, or instead of switching at the zero crossing of the power line input signal voltage). Switching from continuous mode or discontinuous mode to critical mode can also be performed at these times.

The mode control module 520 can generate control signals for switching modes from continuous mode to discontinuous mode or from discontinuous mode to continuous mode based on zero crossing signals, phases, and/or other sensed operational parameters. Based on the selected mode, the switch control module 516 also selects the frequency of the switch.

The switch control module 516 can include an on-time module 524 that sets the on-time t _on for the switch 240 as described herein. The on period t _on can be constant or adjustable. The switch control module 516 can include an off time module 528 that sets the switch 240 to an off period t _off as described herein.

Referring now to FIG. 10A, a method 550 for adjusting the switching frequency of a boost converter begins at step 552. In step 554, control determines if there is a requested mode of operation change. If the result of the determination in step 554 is false, then control returns to step 554. If the result of the determination in step 554 is true, then control continues with step 556 and determines if the continuous mode has been selected. If a continuous mode has been selected, the switching frequency control is provided in step 560 is greater than the critical switching frequency f _c.

If the result of the determination in step 556 is false, then control determines in step 564 whether the discontinuous mode has been selected. If the determination result of step 564 is true, then in step 568 controls the switching frequency of the switching frequency f _c is set smaller than the critical. If the determination result of step 564 is false, control preset in the critical mode in step 572 and the switching frequency is set equal to the critical switching frequency f _c.

It will be appreciated that switching between modes can be performed at any time. In some implementations, the switching frequency can be set as shown in FIG. 10A and the switching can be performed at any time during the period of the power input signal. In some implementations, the switching frequency can be set as shown in FIG. 10A and switching can be performed at the voltage zero crossing as shown in FIG. 10B.

Referring now to FIG. 10B, a method 600 of switching the mode of the boost converter at a voltage zero crossing begins at step 602. In step 606, the mode control module may be based on such V _out, load condition and / or operating conditions of other operating parameters such mode is selected (e.g., continuous mode or discontinuous mode critical mode). In step 608, control determines whether the mode control module 520 requests a mode change. For example, the mode may be changed from one of the continuous mode, the critical mode, or the discontinuous mode to the other of the continuous mode, the critical mode, or the discontinuous mode.

At step 610, mode control module 520 determines if zero crossing module 508 has detected a zero crossing. If the result of step 610 is false, mode control module 520 waits until the zero crossing module detects a zero crossing. If the result of step 610 is true, then in step 614 mode control module 520 switches the mode to the selected mode.

The switching frequency in the continuous mode may be greater than the switching frequency in the discontinuous mode. In particular, the switching frequency in continuous mode is determined based on factors including: the rated power of the boost converter, the estimated load, and the components (by way of example only, inductor 220 and capacitor/filter 260) value.

For example only, the switching frequency in continuous mode may be between 500 KHz and 2 MHz. For example only, the switching frequency in continuous mode may be 1 MHz. The switching frequency in the discontinuous mode may be based on the estimated load current or proportional to the estimated load current.

Referring now to Figure 11, the switch control module 516 can set the switching frequency based on the phase of the power line input signal. In particular, the switching frequency may be greater than the critical switching frequency (threshold frequency) f _c in the continuous mode and may be less than the critical switching frequency f _c in the discontinuous mode. The critical switching frequency f _c can be given by: f _c = 0.25 × (V _p ² ) × (1 - V _p × sin(θ) / V _o ) / (P _o × L) where V _p = 1.44 ×V _RMS is the peak voltage of the power line input signal (for example, V _p = 144 volts when V _RMS = 110 volts), V _o is the output voltage of the boost converter, and P _o is the output power of the boost converter, L Is the inductance value, and θ is the phase of the power line input signal.

The maximum value of the critical switching frequency f _c can be given by: f _max = 0.25 × (V _p ² ) / (P _o × L) Therefore, the critical switching frequency f _c can be expressed as f _max and frequency ratio f _ratio The product is as follows: f _c =f _max ×f _ratio where f _ratio is the _ratio of the switching frequency to the maximum value of the critical switching frequency and is given by: f _ratio = (1-V _p × sin(θ)/V _o ).

The above description of specific embodiments of the invention has been presented for purposes of illustration and description. The descriptions are not intended to be exhaustive or to limit the invention to the precise form disclosed. The embodiments were chosen and described in order to best explain the principles of the invention Other skilled artisans are able to best utilize the invention, as well as various embodiments, which have various modifications that are suitable for the particular use contemplated. It is intended that the scope of the invention be defined by the claims

10‧‧‧Boost Converter

12‧‧‧AC voltage sensing input

15‧‧‧Rectifier

20‧‧‧Inductance

22‧‧‧ Current

25‧‧‧second inductor coil

30‧‧‧Power factor controller

34‧‧‧ nodes

40‧‧‧ switch

50‧‧‧ diode

60‧‧‧ capacitors/filters

200‧‧‧Boost Converter

210‧‧‧ four-way rectifier

212‧‧‧Power line

214‧‧‧Power line

216‧‧‧ nodes

220‧‧‧Inductance

230‧‧‧Power Factor Controller

234‧‧‧Feed current node

235‧‧‧current feedback resistor

240‧‧‧ switch

250‧‧‧ diode

260‧‧‧ capacitors/filters

270‧‧‧load

272‧‧‧ nodes

400‧‧‧Power Factor Controller

410‧‧‧ Comparator block

411‧‧‧ output

412‧‧‧Zero Voltage Cross Locator

413‧‧‧ output

414‧‧‧Voltage Calculator

415‧‧‧ output

416‧‧‧ Critical Mode Controller

417‧‧‧ output

420‧‧‧A/D converter

425‧‧‧ filter

430‧‧‧A/D converter

435‧‧‧ filter

440‧‧‧Digital Signal Processor

445‧‧‧D/A converter

450‧‧‧output driver

500‧‧‧Power Factor Control Module

504‧‧‧ phase detection module

508‧‧‧ Zero Cross Module

512‧‧‧ Peak Voltage Determination Module

516‧‧‧Switch Control Module

520‧‧‧Mode Control Module

524‧‧‧ On-time module

528‧‧‧Shutdown time module

Figure 1 is a schematic diagram of a conventional boost converter.

2 is a graph of voltage and current waveforms at particular nodes in the conventional boost converter of FIG.

3A-3B are graphs of low voltage and low current portions of the waveform of Fig. 2.

4 is a schematic diagram of an exemplary boost converter in accordance with the present invention.

5-6 are graphs of low voltage and low current waveforms for illustrating the operation of the exemplary boost converter of FIG.

7 is a graph of voltage and current waveforms for both the falling and rising values of a voltage half sine wave useful for illustrating the operation of the exemplary boost converter of FIG.

8 is a schematic diagram of another exemplary power factor controller in accordance with the present invention.

9 is a functional block diagram of an alternative exemplary power factor controller in accordance with the present invention.

10A is a flow chart of a method for controlling a switching frequency based on a mode of a boost converter.

10B is a flow chart of a method for controlling transitions between modes based on voltage zero crossings.

Figure 11 is a switching frequency ratio as a function of AC line phase for continuous and discontinuous modes.

200‧‧‧Boost Converter

210‧‧‧ four-way rectifier

212‧‧‧Power line

214‧‧‧Power line

216‧‧‧ nodes

220‧‧‧Inductance

230‧‧‧Power Factor Controller

234‧‧‧Feed current node

235‧‧‧current feedback resistor

240‧‧‧ switch

250‧‧‧ diode

260‧‧‧ capacitors/filters

270‧‧‧load

272‧‧‧ nodes

Claims (24)

A boost converter includes: an inductor that receives an input signal; a switch that controls current supplied to the load by the inductor; and a power factor control module that includes: a mode control module, The mode control module selects an operation mode of the boost converter; the mode of operation of the mode control module includes a continuous mode, a discontinuous mode, and a critical mode, wherein the critical mode occurs when the current is equal to 0; and a switch a control module, the switch control module (i) switches the switch at a switching frequency, (ii) sets the switching frequency to be equal to a first frequency when the mode control module selects the continuous mode, and (iii) Setting the switching frequency to be equal to a second frequency when the mode control module selects the discontinuous mode, wherein the first frequency is different from the second frequency, wherein the switch control module calculates the switch for the discontinuous mode a turn-off period, wherein during the turn-off, the switch control module is in the critical mode by changing the switching frequency between the first frequency and the second frequency The operation blocks the boost converter, and wherein the off period (i) begins at one of the peaks of the current and (ii) ends when the current decreases to a zero crossing. The boost converter of claim 1, wherein the first frequency is greater than the second frequency. The boost converter of claim 1, wherein the switch control module determines the switching frequency independently of measurements of current through the inductor. The boost converter of claim 1, wherein the power factor control module further comprises: a phase detecting module, wherein the phase detecting module determines a period of the input signal; and a peak voltage determining module, the peak The voltage determining module senses a peak voltage of the input signal; and an on-time module that provides an on-time of the switch. The boost converter of claim 3, wherein the power factor control module further comprises: a turn-off time module, the turn-off time module is based on the period of the input signal, the on-time and the peak voltage To calculate the off time of the switch. The boost converter of claim 5, wherein the turn-off time module calculates the turn-off time independently of current measurements through the inductor. The boost converter of claim 4, wherein: the phase detecting module comprises a zero crossing module, the zero crossing module detects a zero crossing of a voltage of the input signal; and the mode control module is based on The zero crossing controls the transition between the discontinuous mode and the continuous mode. The boost converter of claim 4, wherein: the phase detecting module further determines a phase of the input signal; The first frequency is greater than a threshold frequency and the second frequency is less than the threshold frequency; and the threshold frequency is based on the phase of the input signal. The boost converter of claim 8, wherein the threshold frequency is based on: f _c = 0.25 × (V _p ² ) × (1 - V _p × sin(θ) / V _o ) / (P _o × L Where f _c is the threshold frequency, θ is the phase, V _p is the peak voltage of the input signal, V _o is the output voltage of the boost converter, and P _o is the output power of the boost converter And L is the value of the inductance. The boost converter of claim 8, wherein the threshold frequency is based on the peak voltage of the input signal, the output power of the boost converter, and a value of the inductance. The boost converter of claim 8, wherein: the threshold frequency is a product of a maximum threshold frequency and a first value; the maximum threshold frequency is based on the peak voltage of the input signal, the boost conversion The output power of the device and a first inductance value of the inductor; and the first value is based on the peak voltage of the input signal and the output power of the boost converter. The boost converter of claim 1, wherein the switch control module reduces the zero current period of the inductor based on the change in the switching frequency between the first frequency and the second frequency. The boost converter of claim 1, wherein when the current passes through the inductor is zero, The switch control module changes the switching frequency between the first frequency and the second frequency. The boost converter of claim 1, wherein the switch control module calculates the switch based on an on-time of the switch, a period of a power signal received by the inductor, and a peak voltage of the power signal. Turn off the time period. The boost converter of claim 1, wherein the off period is started when the switch is switched to an off state, and the off period is ended when the current is equal to zero. A power factor controller includes: a mode control module, wherein the mode control module selects an operation mode of a power converter, and the mode of operation of the mode control module includes a continuous mode, a discontinuous mode, and a critical mode, wherein The critical mode occurs when the current is equal to 0; and a switch control module (i) switches a switch at a switching frequency to control the current supplied to the load by an inductor, (ii) When the mode control module selects the continuous mode, the switching frequency is set equal to a first frequency, and (iii) when the mode control module selects the discontinuous mode, the switching frequency is set equal to one a second frequency, wherein the first frequency is different from the second frequency, wherein the switch control module determines the switching frequency independently of a current measurement through the inductor, wherein the switch control module calculates the switch for the discontinuous mode One of the off periods, During the off period, by changing the switching frequency between the first frequency and the second frequency, the switch control module blocks the boost converter from operation in the critical mode, and wherein the switch is turned off Period (i) begins at one of the peaks of the current, and (ii) ends when the current decreases to a zero crossing. The power factor controller of claim 16, wherein the first frequency is greater than the second frequency. The power factor controller of claim 16, further comprising: a phase detecting module, wherein the phase detecting module determines a period of an input signal received by the inductor; and a peak voltage determining module, the peak voltage is determined The module senses a peak voltage of the input signal; and an on-time module that provides an on-time of the switch. The power factor controller of claim 18, further comprising: a turn-off time module, wherein the turn-off time module calculates the turn-off of the switch based on the period of the input signal, the turn-on time, and the peak voltage time. The power factor controller of claim 18, wherein: the phase detecting module comprises a zero crossing module, the zero crossing module detecting a zero crossing of a voltage of the input signal; the mode control module is based on the zero Cross control the discontinuous mode and the continuous mode The transition between. The power factor controller of claim 18, wherein: the first frequency is greater than a threshold frequency and the second frequency is less than the threshold frequency, and the threshold frequency is based on the phase of the input signal. The power factor controller of claim 21, wherein the threshold frequency f _{c is} based on: f _c = 0.25 × (V _p ² ) × (1 - V _p × sin(θ) / V _o ) / (P _o ×L) where f _c is the threshold frequency, θ is the phase, V _p is the peak voltage of the input signal, V _o is the output voltage of the power converter, and P _o is the output power of the power converter And L is the value of the inductance. The power factor controller of claim 21, wherein the threshold frequency is based on the peak voltage of the input signal, the output power of the power converter, and a value of the inductance. The power factor controller of claim 21, wherein: the threshold frequency is based on a maximum threshold frequency and a first value; the maximum threshold frequency is based on the peak voltage of the input signal, the power converter An output power and a first inductance value of the inductor; and the first value is based on the peak voltage of the input signal and an output power of the power converter.