Power factor correction system and method

Abstract

A power factor correction (PFC) system and method are provided. The PFC system includes a desired off period module that determines a desired off period for a switch of a PFC circuit based on an input voltage to the PFC circuit and an output voltage of the PFC circuit, a switch control module that transitions the switch from an on state to an off state when a measured current through an inductor of the PFC circuit is greater than a demanded current through the inductor and maintains the switch in the off state for the desired off period after transitioning from the on state to the off state, a voltage control module configured to set an initial current demand through the inductor based on a difference between a desired output voltage of the PFC circuit and an output voltage of the PFC circuit, and a current demand module configured to set the demanded current through the inductor based on the initial current demand and a reference signal.

Description

[0001] This application is a divisional application of Chinese patent application filed on April 14, 2017, with international application number PCT / US2017 / 027699, entitled "Method and Filtering System for Voltage Control", and application number 201780035647.X which entered the Chinese national phase.

[0002] Cross-references to related applications

[0003] This application is a PCT international application filed January 30, 2017, namely U.S. Application No. 15 / 419,464, 15 / 419,423, and 15 / 419,394. This application claims the earliest filing date and priority of U.S. Provisional Application No. 62 / 323,517, 62 / 323,538, 62 / 323,527, and 62 / 323,607, all filed April 15, 2016. The entire disclosure of the aforementioned applications is incorporated herein by reference. Technical Field

[0004] This disclosure relates to a voltage converter, and more specifically, to a method for controlling the switching of the voltage converter and a circuit for a filtering system. Background Technology

[0005] The background description provided herein is for the purpose of presenting the general context of this disclosure. It is neither express nor implied that the work of the currently named inventors within the scope described in this background section, nor aspects described as prior art at the time of filing, are prior art to this disclosure.

[0006] Electric motors are used in a wide variety of industrial and residential applications, including but not limited to heating, ventilation, and air conditioning (HVAC) systems. By way of example only, an electric motor can drive a compressor in an HVAC system. One or more additional motors can also be implemented in an HVAC system. By way of example only, an HVAC system may include another motor driving a fan associated with the compressor. Another motor can be included in an HVAC system to drive a fan associated with the evaporator. Summary of the Invention

[0007] One feature describes a power factor correction (PFC) system. An error control module determines a first current demand based on the difference between a desired DC voltage and a measured DC voltage. A filter module applies a filter to the first current demand to generate a second current demand. A weighting module (i) determines a first weighting value and a second weighting value, respectively, for the first and second current demands, based on the aforementioned difference; (ii) determines a third current demand based on the first current demand and the first weighting value; and (iii) determines a fourth current demand based on the second current demand and the second weighting value. A current demand module determines a final current demand based on the third and fourth current demands. A current control module controls the switching of the PFC device based on the final current demand.

[0008] In another feature, the summation module determines the fifth current demand based on the sum of the third and fourth current demands. The current demand module applies a notch filter to the fifth current demand and determines the final current demand based on the output of the notch filter.

[0009] In another feature, the current demand module sets the final current demand based on the output of the notch filter multiplied by the value of a sinusoidal reference signal, which is generated to be synchronized with the input AC voltage in both phase and frequency.

[0010] In another feature, the filter coefficient module sets the filter coefficients of the notch filter based on the frequency of the input AC voltage.

[0011] In another feature, when the above difference is less than a predetermined value, the weighting module sets the third current requirement to zero.

[0012] In another feature, when the above difference is less than a predetermined value, the weighting module further sets the fourth current demand to be equal to the second current demand.

[0013] In another feature, when the difference is greater than a predetermined value, the weighting module increases the first weighting value and decreases the second weighting value.

[0014] In another feature, when the difference is greater than a predetermined value, the weighting module increases the first weighting value as the difference increases and decreases the second weighting value as the difference increases.

[0015] In another feature, the weighting module sets the third current demand based on the first current demand multiplied by the first weighting value; and sets the fourth current demand based on the second current demand multiplied by the second weighting value.

[0016] In yet another feature, the filter module applies a low-pass filter to the first current demand to generate the second current demand.

[0017] In one aspect, a power factor correction (PFC) method includes: determining a first current demand based on the difference between a desired direct current (DC) voltage and a measured DC voltage; applying a filter to the first current demand to generate a second current demand; determining a first weighting value and a second weighting value, respectively, for the first current demand and the second current demand, based on the difference; determining a third current demand based on the first current demand and the first weighting value; determining a fourth current demand based on the second current demand and the second weighting value; determining a final current demand based on the third current demand and the fourth current demand; and controlling the switching of a PFC device based on the final current demand.

[0018] In another feature, the PFC method further includes: determining a fifth current demand based on the sum of a third current demand and a fourth current demand; and applying a notch filter to the fifth current demand, wherein determining the final current demand includes determining the final current demand based on the output of the notch filter.

[0019] In another feature, determining the final current requirement involves setting the final current requirement based on the output of the notch filter multiplied by the value of a sinusoidal reference signal, which is generated to be synchronized with the input AC voltage in both phase and frequency.

[0020] In another feature, the PFC method also includes setting the filter coefficients of the notch filter based on the frequency of the input AC voltage.

[0021] In another feature, the PFC method also includes setting the third current requirement to zero when the difference is less than a predetermined value.

[0022] In another feature, the PFC method also includes setting the fourth current demand to be equal to the second current demand when the difference is less than a predetermined value.

[0023] In another feature, the PFC method further includes increasing the first weighting value and decreasing the second weighting value when the difference is greater than a predetermined value.

[0024] In another feature, the PFC method further includes increasing the first weighting value as the difference increases and decreasing the second weighting value as the difference increases when the difference is greater than a predetermined value.

[0025] In another feature, the PFC method further includes: setting a third current demand based on a first current demand multiplied by a first weighting value; and setting a fourth current demand based on a second current demand multiplied by a second weighting value.

[0026] In another feature, the filter is a low-pass filter.

[0027] One feature describes a power factor correction (PFC) system. A desired off-time module determines the desired off-time for the switch used in the PFC circuit based on the input voltage to the PFC circuit and the output voltage of the PFC circuit. When the measured current through the inductor of the PFC circuit exceeds the required current through the inductor, the switch control module transitions the switch from an on state to an off state, and maintains the switch in the off state for the desired off-time after the transition.

[0028] In another feature, the voltage control module sets the initial current requirement through the inductor based on the difference between the desired output voltage of the PFC circuit and the output voltage of the PFC circuit.

[0029] In another feature, the desired shutdown period module uses one of the following to set the desired shutdown period: (i) an equation relating the input voltage and output voltage to the desired shutdown period; and (ii) a lookup table relating the input voltage and output voltage to the desired shutdown period.

[0030] In yet another feature, the expected shutdown period module uses the equation: To set the desired shutdown period, where DOP is the desired shutdown period and t is the desired shutdown period. p It is the scheduled switching cycle, v I It is the input voltage, and v o It is the output voltage.

[0031] In another feature, the switch control module: in response to determining that the time interval between (i) the transition from the on state to the off state and (ii) the current time is greater than the desired off period, transitions the switch from the off state to the on state; and keeps the switch in the on state until the measured current through the inductor of the PFC circuit is greater than the required current through the inductor.

[0032] In another feature, the current demand module determines the required current through the inductor based on the difference between the output voltage and the expected value of the output voltage.

[0033] In another feature, the current demand module sets the required current through the inductor based on the initial current demand and the reference signal.

[0034] In another feature, the desired shutdown period module also determines the desired shutdown period based on the switching cycle of the switch.

[0035] In another feature, the desired on-time module determines the desired on-time for switching, which is variable, and the desired off-time module sets the desired off-time based on the switching cycle minus the desired on-time.

[0036] In another feature, the desired turn-on period module sets the desired turn-on period for switching based on the maximum current through the inductor, the required current through the inductor, and the input voltage, while the desired turn-off period module sets the desired turn-off period based on the switching cycle minus the desired turn-on period.

[0037] In another feature, the desired turn-on period module sets the desired turn-on period for switching based on the maximum current through the inductor, the required current through the inductor, the input voltage, and the output voltage. The desired turn-off period module sets the desired turn-off period based on the switching cycle minus the desired turn-on period.

[0038] In another feature, the discontinuous mode turn-on period module determines a first expected turn-on period for discontinuous mode operation based on the maximum current through the inductor, the required current through the inductor, and the input voltage; the continuous mode turn-on period module determines a second expected turn-on period for continuous mode operation based on the maximum current through the inductor, the required current through the inductor, the input voltage, and the output voltage; and the expected turn-on period module sets a third expected turn-on period for switching as one of the first and second expected turn-on periods. The expected turn-off period module sets the expected turn-off period based on the switching cycle minus the third expected turn-on period.

[0039] In one feature, the power factor correction (PFC) method includes: determining a desired off-time for a switch used in the PFC circuit based on the input voltage to the PFC circuit and the output voltage of the PFC circuit; switching the switch from an on state to an off state when a measured current through an inductor of the PFC circuit is greater than a required current through the inductor; maintaining the switch in the off state for the desired off-time after switching from the on state to the off state; setting an initial current requirement through the inductor based on the difference between the desired output voltage of the PFC circuit and the output voltage of the PFC circuit; and setting a required current through the inductor based on the initial current requirement and a reference signal.

[0040] In another feature, determining the desired shutdown period includes setting the desired shutdown period using one of the following: (i) an equation relating the input voltage and output voltage to the desired shutdown period; and (ii) a lookup table relating the input voltage and output voltage to the desired shutdown period.

[0041] In another feature, determining the desired shutdown period involves using the equation: To set the desired shutdown period, where DOP is the desired shutdown period and t is the desired shutdown period. p It is the scheduled switching cycle, v I It is the input voltage, and v o It is the output voltage.

[0042] In yet another feature, the PFC method further includes: in response to determining that the time interval between (i) the transition from the ON state to the OFF state and (ii) the current time is greater than the desired OFF period, switching the switch from the OFF state to the ON state; and maintaining the switch in the ON state until the measured current through the inductor of the PFC circuit is greater than the required current through the inductor.

[0043] In another feature, the PFC method also includes determining the required current through the inductor based on the difference between the output voltage and the expected value of the output voltage.

[0044] In another feature, determining the desired shutdown period includes further determining the desired shutdown period based on the switching cycle of the switch.

[0045] In another feature, the PFC method also includes determining the desired on-time of the switch, wherein the desired on-time is variable. Determining the desired off-time includes setting the desired off-time based on the switching cycle minus the desired on-time.

[0046] In another feature, determining the desired turn-on period includes setting the desired turn-on period for switching based on the maximum current through the inductor, the required current through the inductor, and the input voltage. The desired turn-off period module sets the desired turn-off period based on the switching cycle minus the desired turn-on period.

[0047] In another feature, the PFC method also includes setting the desired on-time for switching based on the maximum current through the inductor, the required current through the inductor, the input voltage, and the output voltage. Determining the desired off-time includes setting the desired off-time based on the switching cycle minus the desired on-time.

[0048] In another feature, the PFC method further includes: determining a first expected turn-on period for discontinuous mode operation based on the maximum current through the inductor, the required current through the inductor, and the input voltage; determining a second expected turn-on period for continuous mode operation based on the maximum current through the inductor, the required current through the inductor, the input voltage, and the output voltage; and setting a third expected turn-on period for switching as one of the first and second expected turn-on periods. Determining the desired turn-off period includes setting the desired turn-off period based on the switching cycle minus the third expected turn-on period.

[0049] One feature describes a power factor correction (PFC) system. The PFC circuit receives an alternating current (AC) input voltage and uses a switch to generate a direct current (DC) output voltage based on the AC input voltage. A first zero-crossing module determines a first zero-crossing point of the AC input voltage based on: a first voltage and a first time when the AC input voltage transitions from less than a first predetermined voltage to greater than a first predetermined voltage; and a second voltage and a second time when the AC input voltage transitions from less than a second predetermined voltage to greater than a second predetermined voltage. The first predetermined voltage is less than zero, and the second predetermined voltage is greater than zero. A reference module generates a sinusoidal reference signal based on the first zero-crossing point, corresponding at least in phase and frequency to the AC input voltage. A switch control module controls the switching of the switch based on the sinusoidal reference signal.

[0050] In another feature, the second zero-crossing module determines the second zero-crossing point of the sinusoidal reference signal based on: a first value of the sinusoidal reference signal and a third time when the sinusoidal reference signal transitions from greater than a third predetermined voltage to less than a third predetermined voltage; and a second value of the sinusoidal reference signal and a fourth time when the sinusoidal reference signal transitions from greater than a fourth predetermined voltage to less than a fourth predetermined voltage. The fourth predetermined voltage is less than zero, and the third predetermined voltage is greater than zero. The reference module also generates a sinusoidal reference signal based on the second zero-crossing point.

[0051] In another feature, the reference module generates a sinusoidal reference signal based on the difference between the first zero-crossing point of the AC input voltage and the second zero-crossing point of the sinusoidal reference signal.

[0052] In yet another feature, the third predetermined voltage is equal to the second predetermined voltage, and the fourth predetermined voltage is equal to the first predetermined voltage.

[0053] In another feature, the reference module also generates a sinusoidal reference signal based on half a period difference between the first zero-crossing point of the AC input voltage and the second zero-crossing point of the sinusoidal reference signal.

[0054] In another feature, the first predetermined voltage and the second predetermined voltage are equal in magnitude, and the third predetermined voltage and the fourth predetermined voltage are equal in magnitude.

[0055] In another feature, the filter module filters the value of the AC input voltage measured using a voltage sensor and generates a first voltage and a second voltage based on the filtering.

[0056] In another feature, the filter correction module determines the correction for the first zero-crossing point based on the frequency of the AC input voltage. The reference module generates a sinusoidal reference signal based on the above correction.

[0057] In another feature, the first zero-crossing module uses linear interpolation based on a first voltage, a first time, a second voltage, and a second time to determine the first zero-crossing point of the AC input voltage.

[0058] In another feature, the current demand module determines the current demand based on a sinusoidal reference signal, and when the current measured through the inductor of the PFC circuit is greater than the demand current, the switch control module switches the switch from the on state to the off state.

[0059] In one embodiment, the power factor correction (PFC) method includes: receiving an alternating current (AC) input voltage via a PFC circuit, and generating a direct current (DC) output voltage using a switch based on the AC input voltage; and determining a first zero-crossing point of the AC input voltage based on: a first voltage and a first time when the AC input voltage transitions from less than a first predetermined voltage to greater than a first predetermined voltage, and a second voltage and a second time when the AC input voltage transitions from less than a second predetermined voltage to greater than a second predetermined voltage. The first predetermined voltage is less than zero, and the second predetermined voltage is greater than zero. The PFC method further includes: generating a sinusoidal reference signal corresponding at least in phase and frequency to the AC input voltage based on the first zero-crossing point; and controlling the switching of the switch based on the sinusoidal reference signal.

[0060] In another feature, the PFC method further includes determining a second zero-crossing point of the sinusoidal reference signal based on: a first value of the sinusoidal reference signal and a third time when the sinusoidal reference signal transitions from greater than a third predetermined voltage to less than a third predetermined voltage; and a second value of the sinusoidal reference signal and a fourth time when the sinusoidal reference signal transitions from greater than a fourth predetermined voltage to less than a fourth predetermined voltage. The fourth predetermined voltage is less than zero, and the third predetermined voltage is greater than zero. Generating the sinusoidal reference signal also includes generating the sinusoidal reference signal based on the second zero-crossing point.

[0061] In another feature, generating the sinusoidal reference signal involves generating the sinusoidal reference signal based on the difference between the first zero-crossing point of the AC input voltage and the second zero-crossing point of the sinusoidal reference signal.

[0062] In yet another feature, the third predetermined voltage is equal to the second predetermined voltage, and the fourth predetermined voltage is equal to the first predetermined voltage.

[0063] In another feature, generating the sinusoidal reference signal includes further generating the sinusoidal reference signal based on half a period difference between the first zero-crossing point of the AC input voltage and the second zero-crossing point of the sinusoidal reference signal.

[0064] In another feature, the first predetermined voltage and the second predetermined voltage are equal in magnitude, and the third predetermined voltage and the fourth predetermined voltage are equal in magnitude.

[0065] In another feature, the PFC method further includes: filtering the value of the AC input voltage measured using a voltage sensor; and generating a first voltage and a second voltage based on the filtering.

[0066] In another feature, the PFC method further includes determining a correction for the first zero-crossing point based on the frequency of the AC input voltage. Generating a sinusoidal reference signal further includes generating a sinusoidal reference signal based on the above correction.

[0067] In another feature, determining the first zero-crossing point includes using linear interpolation based on a first voltage, a first time, a second voltage, and a second time to determine the first zero-crossing point of the AC input voltage.

[0068] In another feature, the PFC method also includes determining the current demand based on a sinusoidal reference signal. Controlling the switching involves changing the switch from an on state to an off state when the measured current through the inductor of the PFC circuit is greater than the demand current.

[0069] Further applications of this disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are intended for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0070] This disclosure will be more fully understood based on the detailed description and accompanying drawings, in which:

[0071] Figure 1 This is a functional block diagram of an example refrigeration system;

[0072] Figure 2 yes Figure 1 A block diagram illustrating an example implementation of a compressor motor drive;

[0073] Figure 3A yes Figure 2 A block diagram illustrating an example implementation of a power factor correction (PFC) circuit;

[0074] Figure 3B yes Figure 2 A block diagram of another example implementation of the PFC circuit;

[0075] Figure 4A yes Figure 3A Functional block diagram of an example implementation of a PFC circuit;

[0076] Figure 4B yes Figure 3B Functional block diagram of an example implementation of a PFC circuit;

[0077] Figure 5 This is a functional block diagram of an example implementation of the control module;

[0078] Figure 6 This is a functional block diagram of an example implementation of the voltage control module;

[0079] Figures 7 to 8 Here is an example graph of current versus time;

[0080] Figure 9 This is a functional block diagram of an example implementation of the current demand module;

[0081] Figure 10 Here is an example graph of current versus time;

[0082] Figure 11 This is an example graph showing the measured DC bus voltage versus time;

[0083] Figure 12 and Figure 13 These are example graphs showing current versus time under light load and heavy load conditions, respectively.

[0084] Figure 14 and Figure 15 These are example graphs showing current versus time under light load and heavy load conditions, respectively.

[0085] Figure 16 This is an example graph showing the change in measured DC bus voltage versus time in response to a step change between heavy and light load conditions.

[0086] Figure 17 This is a flowchart depicting an example method for determining the final current requirement;

[0087] Figures 18 to 19 This is a functional block diagram of an example implementation of the current control module;

[0088] Figures 20 to 21 This is an example graph of current versus time for non-periodic current ripple.

[0089] Figures 22 to 25 Includes example graphs of input voltage, output voltage, and current versus time under load conditions resulting from the use of variable desired off-time.

[0090] Figure 26 It is a flowchart of an example method that includes determining the desired off-time of a switch and controlling the switch based on the desired off-time.

[0091] Figure 27A and Figure 27B A functional block diagram of an example implementation of the reference signal generation module;

[0092] Figure 27C and Figure 27D A functional block diagram of an example implementation of the reference signal generation module;

[0093] Figure 27E and Figure 27F A functional block diagram of an example implementation of the reference signal generation module;

[0094] Figure 28 Includes example graphs of filtered AC input voltage versus time;

[0095] Figure 29 Includes example diagrams of filter correction and supply frequency;

[0096] Figure 30 Example graphs showing voltage versus time for the reference signal;

[0097] Figure 31 This is a flowchart depicting an example method for determining the zero-crossing point of an AC line;

[0098] Figure 32 This is a flowchart depicting an example method for determining the zero-crossing point of a reference signal;

[0099] Figure 33 This is a flowchart depicting an example method for generating a reference signal.

[0100] In the accompanying drawings, reference numerals may be reused to identify similar and / or identical elements. Detailed Implementation

[0101] Figure 1 This is a functional block diagram of an example refrigeration system 100 including a compressor 102, a condenser 104, an expansion valve 106, and an evaporator 108. Based on the principles of this disclosure, the refrigeration system 100 may include additional and / or alternative components, such as reversing valves or filter-dryers. Furthermore, this disclosure is applicable to other types of refrigeration systems, including but not limited to heating, ventilation, and air conditioning (HVAC) systems, heat pump systems, refrigeration systems, and cooling systems.

[0102] Compressor 102 receives refrigerant in vapor form and compresses the refrigerant. Compressor 102 provides pressurized refrigerant in vapor form to condenser 104. Compressor 102 includes a motor that drives a pump. By way of example only, the pump of compressor 102 may include a scroll compressor and / or a reciprocating compressor.

[0103] All or part of the pressurized refrigerant is converted into a liquid form within condenser 104. Condenser 104 transfers heat away from the refrigerant, thereby cooling it. When the refrigerant vapor is cooled to a temperature below its saturation temperature, the refrigerant transforms into a liquid (or liquefied) refrigerant. Condenser 104 may include an electric fan to increase the rate at which heat is transferred from the refrigerant.

[0104] The condenser 104 supplies refrigerant to the evaporator 108 via the expansion valve 106. The expansion valve 106 controls the flow rate of refrigerant supplied to the evaporator 108. The expansion valve 106 may include a thermostatic expansion valve or may be electrically controlled, for example, by a system controller 130. The pressure drop caused by the expansion valve 106 can convert a portion of the liquefied refrigerant back into vapor form. Thus, the evaporator 108 can receive a mixture of refrigerant vapor and liquefied refrigerant.

[0105] The refrigerant absorbs heat in the evaporator 108. The liquid refrigerant transforms into vapor when heated to a temperature higher than its saturation temperature. The evaporator 108 may include an electric fan to increase the rate at which heat is transferred to the refrigerant.

[0106] Utility 120 supplies electricity to cooling system 100. For example only, utility 120 can provide approximately 230 volts (RMS). RMS The utility 120 provides single-phase alternating current (AC) power. In other implementations, utility 120 may provide approximately 400V at a line frequency of, for example, 50Hz or 60Hz. RMS 480V RMS Or 600V RMS Three-phase AC power. When the three-phase AC power is rated at 600V... RMS At that time, the actual usable voltage of electricity can be 575V. RMS .

[0107] The utility 120 can supply AC power to the system controller 130 via an AC line comprising two or more conductors. AC power can also be supplied to the drive 132 via the AC line. The system controller 130 controls the refrigeration system 100. By way of example only, the system controller 130 can control the refrigeration system 100 based on user input and / or parameters measured by various sensors (not shown). Sensors may include pressure sensors, temperature sensors, current sensors, voltage sensors, etc. Sensors may also include feedback information from the drive control via a serial data bus or other suitable data bus, such as motor current or torque.

[0108] User interface 134 provides user input to system controller 130. User interface 134 may additionally or alternatively provide user input directly to drive 132. For example, user input may include desired temperature, requests related to fan operation (e.g., requests for continuous operation of the evaporator fan), and / or other appropriate input. User interface 134 may take the form of a thermostat, and some or all of the functions of the system controller (e.g., including starting a heat source) may be incorporated into the thermostat.

[0109] System controller 130 can control the operation of the fan of condenser 104, the fan of evaporator 108, and expansion valve 106. Drive 132 can control compressor 102 based on commands from system controller 130. By way of example only, system controller 130 can instruct drive 132 to operate the motor of compressor 102 at a specific speed or to operate compressor 102 at a specific capacity. In various implementations, drive 132 can also control the condenser fan.

[0110] Thermistor 140 is thermally coupled to the refrigerant line exiting compressor 102, which delivers refrigerant vapor to condenser 104. Therefore, the variable resistance of thermistor 140 varies with the discharge line temperature (DLT) of compressor 102. As described in more detail, drive 132 monitors the resistance of thermistor 140 to determine the temperature of the refrigerant leaving compressor 102.

[0111] For example, the DLT can be used to control the compressor 102 by changing its capacity, and it can also be used to detect faults. For example, if the DLT exceeds a threshold, the drive 132 can de-energize the compressor 102 to prevent damage to the compressor 102.

[0112] drive

[0113] exist Figure 2 In this example implementation, the driver 132 includes an electromagnetic interference (EMI) filter and protection circuit 204 that receives power from the AC line. The EMI filter and protection circuit 204 reduces EMI that might otherwise be injected back onto the AC line from the driver 132. The EMI filter and protection circuit 204 can also remove or reduce EMI from the AC line. Furthermore, for example, the EMI filter and protection circuit 204 prevents power surges and / or other types of surges and power spikes / dips that might be caused by lightning.

[0114] Charging circuit 208 controls the power supplied from EMI filter and protection circuit 204 to power factor correction (PFC) circuit 212. For example, when drive 132 is initially powered on, charging circuit 208 can place a series resistor between EMI filter and protection circuit 204 and PFC circuit 212 to reduce the amount of current inrush. These current or power spikes can cause premature failure of various components.

[0115] After the initial charging is complete, the charging circuit 208 can close the relay that bypasses the current-limiting resistor. For example, the control module 220 can provide a relay control signal to the relay within the charging circuit 208. In various implementations, the control module 220 can activate the relay control signal to bypass the current-limiting resistor after a predetermined period of time following startup or based on closed-loop feedback indicating that charging is nearing completion.

[0116] PFC circuit 212 converts input AC power into DC power. PFC circuit 212 is not limited to PFC functions; for example, it can also perform voltage conversion functions, such as acting as a boost and / or buck circuit. In some implementations, PFC circuit 212 can be replaced by a non-PFC voltage converter. DC power may have voltage ripple, which is reduced by filter capacitor 224. Filter capacitor 224 may include one or more capacitors arranged in parallel and connected to the DC bus. PFC circuit 212 may attempt to draw current from the AC line in a sinusoidal pattern that matches the sinusoidal pattern of the input voltage. When the sinusoids are aligned, the power factor is close to 1, representing maximum efficiency and minimum demand load on the AC line.

[0117] PFC circuit 212 includes one or more switches controlled by control module 220 using one or more signals labeled power switching control. Control module 220 determines the power switching control signal based on: a measured voltage on the DC bus, a measured current in PFC circuit 212, AC line voltage, one or more temperatures of PFC circuit 212, and a measured state of the power switches in PFC circuit 212. While examples using measured values ​​are provided, control module 220 may determine the power switching control signal based on: an estimated voltage on the DC bus, an estimated current in PFC circuit 212, an estimated AC line voltage, one or more estimated temperatures of PFC circuit 212, and / or an estimated or expected state of the power switches in PFC circuit 212. In various implementations, the AC line voltage is measured or estimated after the EMI filter and protection circuit 240 but before the charging circuit 208.

[0118] Control module 220 is powered by DC-DC power supply 228, which provides a voltage suitable for the logic of control module 220, such as 3.3 volts, 2.5 volts, etc. DC-DC power supply 228 can also provide DC power for operating the switches of PFC circuit 212 and inverter power supply circuit 232. As an example only, this voltage can be higher than that of the digital logic; one example is 15 volts.

[0119] The inverter power supply circuit 232 also receives power switching control signals from the control module 220. In response to the power switching control signals, a switch within the inverter power supply circuit 232 allows current to flow into the corresponding winding of the motor 236 of the compressor 102. The control module 220 can receive measured or estimated values ​​of the motor current for each winding of the motor 236 or for each branch of the inverter power supply circuit 232. The control module 220 can also receive temperature indications from the inverter power supply circuit 232.

[0120] By way of example only, the temperatures received from the inverter power supply circuit 232 and the PFC circuit 212 are used solely for fault purposes. In other words, once the temperature exceeds a predetermined threshold, a fault is reported and drive 132 is either powered off or operates at reduced capacity. For example, drive 132 may operate at reduced capacity and if the temperature does not decrease at a predetermined rate, drive 132 switches to a shutdown state.

[0121] The control module 220 can also use the thermistor 140 to receive an indication of the discharge line temperature from the compressor 102. The isolation circuit 260 can provide a pulse-width modulated representation of the resistance of the thermistor 140 to the control module 220. The isolation circuit 260 may include electrical isolation such that there is no electrical connection between the thermistor 140 and the control module 220.

[0122] The isolation circuit 260 can also receive protection inputs indicating faults (e.g., high-pressure cutoff or low-pressure cutoff, where pressure refers to refrigerant pressure). If any protection input indicates a fault, and in some implementations, if any protection input becomes disconnected from the isolation circuit 260, the isolation circuit 260 stops sending PWM temperature signals to the control module 220. Therefore, the control module 220 can infer the receipt of a protection input based on the absence of the PWM signal. In response, the control module 220 can shut down the drive 132.

[0123] Control module 220 controls integrated display 264, which may include a grid of LEDs and / or individual LED packages, and may be tri-color LEDs. Control module 220 can use integrated display 264 to provide status information, such as firmware version and error information. Control module 220 uses communication transceiver 268 to communicate with external devices (e.g., Figure 1 The system controller 130 communicates with the system. By way of example only, the communication transceiver 268 may conform to the RS-485 or RS-232 serial bus standard or the Controller Area Network (CAN) bus standard.

[0124] PFC circuit

[0125] exist Figure 3AIn the middle, PFC circuit 300 is Figure 2 One implementation of the PFC circuit 212. The PFC circuit 300 includes a rectifier 304 that converts the input AC to pulsating DC. In various implementations, the rectifier 304 includes a full-wave diode bridge. The DC output of the rectifier 304 is connected to a first terminal and a second terminal. The first terminal is connected to an inductor 308, while the second terminal is connected to a current sensor 312. The opposite end of the inductor 308 is connected to a common node of the inductor 308, the anode of the diode 316, and the first terminal of the switch 320.

[0126] PFC circuit 300 generates a DC bus, wherein the first terminal of the DC bus is connected to the cathode of diode 316, and the second terminal of the DC bus is connected to the second output terminal of rectifier 304 via current sensor 312. Therefore, current sensor 312 can sense the current in switch 320, as well as the current in the DC bus and the current in inductor 308. The second terminal of the DC bus is also connected to the second terminal of switch 320.

[0127] Driver 324 receives from Figure 2 The control module 220 receives a power switching control signal and rapidly charges or discharges the control terminal of the switch 320. For example, the switch 320 may be a field-effect transistor with its gate terminal as the control terminal. More specifically, the switch 320 may be a power metal-oxide-semiconductor field-effect transistor (MOSFET), such as the STW38N65M5 power MOSFET from STMicroelectronics. In response to the power switching control signal, the driver 324 charges or discharges the capacitance at the gate of the field-effect transistor.

[0128] The switch monitoring circuit 328 measures whether the switch is on or off. This closed-loop control enables the control module 220 to determine whether the switch 320 has responded to the command provided by the power switching control signal and can also be used to determine how long it takes for the switch 320 to respond to the aforementioned control signal. The measured switch state is output from the switch monitoring circuit 328 back to the control module 220. The control module 220 can update its control of the power switching control signal to compensate for the delay in turning the switch 320 on and / or off.

[0129] exist Figure 3AIn this configuration, the inductor, switch 320, and diode 316 are arranged in a boost configuration. In short, when switch 320 closes, the current through inductor 308 increases. Then, when switch 320 opens, the current through inductor 308 does not immediately change because the voltage across the inductor is proportional to the derivative of the current. The voltage across inductor 308 becomes negative, meaning that the end of inductor 308 connected to the anode of diode 316 experiences a voltage increase higher than the voltage output from rectifier 304.

[0130] Once the voltage at the anode of diode 316 increases to a level higher than the forward voltage of diode 316, the current through inductor 308 can be fed to the DC bus through diode 316. The current through inductor 308 decreases and then switch 320 closes again, causing the current and inductor 308 to increase.

[0131] In various implementations, switch 320 can be turned on until current sensor 312 determines that a predetermined current threshold has been exceeded. At this point, switch 320 turns off for a specific period of time. This specific period of time can be adaptive, changing with variations in the DC bus voltage and the AC input voltage. However, the turn-off time (when the switch is off) is a specific value. Once the time equal to the specific value has elapsed, switch 320 turns on again and the process repeats. The turn-off time can be fixed or variable. In the case where the turn-off time is variable, the turn-off time can be limited to at least a predetermined minimum turn-off time.

[0132] To reduce the physical size and component cost of the PFC circuit 300, the inductance of inductor 308 (which is likely the largest contributor to the physical size of the PFC circuit 300) can be reduced. However, with a lower inductance, inductor 308 will saturate more quickly. Therefore, switch 320 must operate more quickly. However, faster and smaller are relative terms; currently, power switching controls operate in the range of 10 kHz to 20 kHz switching frequencies. In this application, the switching frequency of switch 320 can be increased to greater than 50 kHz, greater than 100 kHz, or greater than 200 kHz. For example, the switching frequency of the switch can be controlled to approximately 200 kHz.

[0133] Therefore, switch 320 is selected to allow for faster switching and very low switching losses. With faster switching, the inductance of inductor 308 can be smaller. Additionally, diode 316 may require even faster switching. Silicon carbide diodes can have very fast response times. For example, diode 316 could be an STPSC2006CW silicon carbide dual diode package from STMicroelectronics.

[0134] To precisely drive switch 320 at higher speeds, a similarly accelerated control strategy must be employed. As an example only, control module 220 may include multiple devices, such as a microcontroller configured to perform more relevant calculations and an FPGA (Field-Programmable Gate Array) or PLD (Programmable Logic Device) configured to monitor and respond to inputs in near real-time. In this context, near real-time means that the temporal resolution and time delay of measurements responding to inputs from the FPGA or PLD are negligible compared to the physical timescale of interest. For faster switching speeds, the near real-time response of the FPGA / PLD may introduce non-negligible delays. In such cases, the delays of the FPGA / PLD and drive circuitry system can be measured and compensated for. For example, if switch turn-off occurs later than required due to a delay, turn-off can be indicated earlier to compensate for the delay.

[0135] The bypass rectifier 340 is connected in parallel with the rectifier 304 at the AC line input. The second output terminal of the bypass rectifier 340 is connected to the second terminal of the rectifier 304. However, the first output terminal of the bypass rectifier 340 is connected to the cathode of the diode 316.

[0136] As a result, when the PFC circuit 300 is not operating to increase the DC bus voltage, the bypass rectifier 340 will be activated when the line-to-line voltage of the AC input exceeds the voltage across the DC bus. In this case, the bypass rectifier 340 diverts current without passing through the diode 316. Because the inductor 308 is small and the switch 320 switches rapidly, the diode 316 is also selected to exhibit a very fast switching time. Therefore, the diode 316 is less able to withstand high currents, thus the bypass rectifier 340 selectively shunts the current around the diode 316.

[0137] Furthermore, the current path through rectifier 304 and diode 316 experiences three diode voltage drops or two diode voltage drops and a switching voltage drop, while the path through bypass rectifier 340 experiences only two diode voltage drops. Although Figure 3A The single-phase AC input in the circuit is associated with a boost converter topology, and this disclosure also includes a buck converter topology or a buck-boost converter topology.

[0138] exist Figure 3B In the diagram, a buck converter topology is shown with a three-phase AC input signal. Note that the principles of this disclosure also apply to boost converter or buck-boost converter topologies using a three-phase AC input. PFC circuit 350 is shown. Figure 2 Another implementation of the PFC circuit 212.

[0139] Three-phase rectifier 354 receives three-phase AC and generates pulsating DC across the first and second terminals. Switch 358 is connected between the first terminal of three-phase rectifier 354 and a common node. The common node is connected to the cathodes of inductor 366 and power diode 370.

[0140] The anode of power diode 370 is connected to the second terminal of three-phase rectifier 354. The opposite terminal of inductor 366 becomes one terminal of the DC bus, while the second output of three-phase rectifier 354 becomes the other terminal of the DC bus. Figure 3B In the configuration shown, switch 358, inductor 366, and diode 370 are configured as a buck topology.

[0141] Current sensor 362 is connected in series between the anode of diode 370 and the DC bus. In other implementations, current sensor 362 may be placed in series with inductor 366. In other implementations, current sensor 362 may be placed in series with switch 358. In other implementations, current sensor 362 may be placed in series between the anode of diode 370 and the second output terminal of three-phase rectifier 354. Current sensor 362 measures the current through inductor 366 and the current through the DC bus, and provides a current signal indicating the amount of current.

[0142] Driver 374 is based on from Figure 2 The power switching control signal of the control module 220 drives the control terminals of the switch 358. The switch monitoring circuit 378 detects whether the switch 358 is open or closed and reports the switch status to the control module 220. Using the position of the current sensor 362, when the switch 358 is open, the current sensor 362 will measure a current of approximately zero.

[0143] Figure 4A yes Figure 3A A simplified functional block diagram of the PFC circuit 300 and control module 220 is shown below. Rectifier 304 rectifies the AC input voltage to generate a DC voltage. This DC voltage is represented by DC voltage 404 in Figure 4. Control module 220 controls the switching of switch 320 to convert DC voltage 404 into a DC bus voltage greater than DC voltage 404. Therefore, the PFC circuit 300 includes... Figure 3A The example of the boost converter in Figure 4 illustrates this. A boost converter transforms an input voltage (e.g., DC voltage 404) into a higher output voltage (e.g., DC bus voltage). This application applies to both single-phase and three-phase boost converters.

[0144] Figure 4B yes Figure 3BA simplified functional block diagram of one phase of the PFC circuit 350 and the control module 220. The three-phase rectifier 354 rectifies the three-phase AC input voltage to generate a three-phase DC voltage. The DC voltage of one phase of the three phases is generated by... Figure 4B The DC voltage 504 in the figure represents the input voltage. The control module 220 controls the switching of phase switches to convert the DC voltage input to the three phases into a DC bus voltage lower than the input voltage. Therefore, the PFC circuit 350 includes... Figure 3B and Figure 4B The example shows a buck converter. A buck converter transforms an input voltage into a lower output voltage. This application applies to both single-phase and three-phase buck converters. Some converters can be used as combined boost / buck converters.

[0145] Figure 5 This is a functional block diagram of an example implementation of control module 220. The concepts described below apply to boost converters, such as... Figure 3A and Figure 4A Examples. The concepts described below also apply to buck converters, such as... Figure 3B and Figure 4B Examples.

[0146] The desired voltage module 604 determines the desired DC bus voltage. The desired DC bus voltage can be a fixed, predetermined value or it can be variable. For example, the desired voltage module 604 can be based on the peak voltage (V) of the AC line. PEAK The desired DC bus voltage is determined by at least one of ( ) and / or multiple system parameters.

[0147] By way of example only, multiple system parameters may include, but are not limited to, actual and indicated compressor speed, actual and estimated inverter output power, actual and estimated drive output power, input and output current, drive input voltage, inverter output voltage, estimated motor torque, various temperatures, and requirements from condenser 104. For example, various temperatures may include the temperatures of PFC circuit 212, inverter power supply circuit 232, circuit boards, compressor scroll, and motor 236. By way of example, a lookup table may include values ​​for possible AC peak voltages V. PEAK The desired DC bus voltage V corresponding to each of the different combinations of multiple system parameters. DESThe desired voltage module 604 can use a lookup table to determine the desired DC bus voltage. For values ​​between entries in the lookup table, the desired voltage module 604 can use interpolation to determine the desired DC bus voltage. Further examples of setting the desired DC bus voltage are provided in U.S. Provisional Application No. 0315-000927-US-PS1, filed April 15, 2016, entitled “Power Factor Correction Circuits and Methods Including Partial Power Factor Correction Operation for Boost and Buck Power Converters,” the entire contents of which are incorporated herein by reference.

[0148] Voltage control module 608 (see also) Figure 6 The voltage control module 608 determines the difference between the desired DC bus voltage and the measured DC bus voltage, and determines a first current demand based on this difference. The voltage control module 608 applies a filter to the first current demand and determines an initial current demand based on the first current demand and the filtered current demand.

[0149] The voltage control module 608 weights the contributions of the first current demand and the filtered current demand to the initial current demand based on the difference between the measured DC bus voltage and the desired DC bus voltage. More specifically, when the difference is small, the voltage control module 608 applies a larger weight to the filtered current demand. As the difference increases, the voltage control module 608 increases the weight of the first current demand and decreases the weight of the filtered current demand.

[0150] Current demand module 612 (see example) Figure 9 A filter (e.g., a notch filter) can be applied to the initial current demand. The current demand module 612 can also perform one or more signal processing functions to reduce noise in the initial current demand. The current demand module 612 multiplies the (filtered) initial current demand with a reference signal to produce the final current demand. While an example of a current demand module 612 filtering the initial current demand is provided, in other examples, the current demand module 612 may not filter the initial current demand. In this case, the initial current demand can be multiplied with a reference signal to produce the final current demand.

[0151] Reference generation module 616 (see example) Figure 27A and Figure 27BThe zero-crossing point and reference signal of the AC line are determined. Based on the zero-crossing point, the reference generation module 616 generates a reference signal to track the AC input voltage in phase and frequency. Therefore, for example, the final current demand follows the AC input voltage to maximize the power factor.

[0152] Current control module 620 (see example) Figure 18 and Figure 19 The current control module 620 controls the switching of switch 320. More specifically, when the measured current exceeds the current demand, the current control module 620 switches switch 320 to off. The current control module 620 then keeps switch 320 off for the desired off period. The desired off period is variable, and for example, the current control module 620 determines the desired off period based on the AC input voltage and / or the measured DC bus voltage.

[0153] Figure 6 This is a functional block diagram of an example implementation of voltage control module 608. As described above, voltage control module 608 generates an initial current demand based on the desired DC bus voltage and the measured DC bus voltage. The initial current demand corresponds to a target value used for measuring the current. The measured DC bus voltage is measured using a voltage sensor. The desired DC bus voltage is determined by desired voltage module 604.

[0154] Voltage control module 608 includes error control module 704 that receives a desired DC bus voltage and a measured DC bus voltage. Error control module 704 generates a first current demand to minimize the difference between the desired DC bus voltage and the measured DC bus voltage.

[0155] For example, subtraction module 708 subtracts the measured DC bus voltage from the desired DC bus voltage to determine the DC voltage error. Proportioning module 712 multiplies the DC voltage error by a proportionality constant. Integrator module 716 combines the DC voltage error with its previous output. Integrator module 716 first multiplies the DC voltage error by an integration constant. Integrator module 716 may also apply upper and / or lower limits to its output. In various implementations, integrator module 716 may bias its output toward a tracking input (e.g., a second current demand).

[0156] The summation module 720 adds the output of the proportional module 712 to the output of the integrator module 716. The sum from the summation module 720 is output from the error control module 704 as a first current demand. Although the error control module 704 is shown as a proportional-integral (PI) controller for illustrative purposes, another suitable type of closed-loop controller can be used. Alternatively, a feedforward component can be implemented to generate the first current demand by adding it to a feedback component (e.g., a sum).

[0157] Filter module 724 applies a filter to the first current demand to generate a second current demand. For example, the filter could be a low-pass filter (LPF) or another suitable type of filter. For instance, the filter's cutoff frequency can be calibrated to smooth the cyclic ripple that can be attributed to error control module 704. Filter module 724 can reduce bandwidth and can smooth / attenuate the cyclic ripple generated by error control module 704, which attempts to adjust the measured DC bus voltage toward the desired DC bus voltage. This is merely an example. Figure 7 Includes example graphs of the current generated by a PI controller based on a sinusoidal input voltage. Figure 8 Includes example graphs of the current generated by low-pass filtering of the output of a PI controller.

[0158] Come back for reference Figure 6 The voltage control module 608 also includes a weighting module that weights the contributions of the first current demand and the second current demand to the initial current demand. As the DC voltage error increases, the weighting module reduces the use of the second current demand and increases the use of the first current demand. This minimizes harmonics and the response time to load changes.

[0159] The absolute value module 728 determines and outputs the absolute value (i.e., amplitude) of the DC voltage error. The bias module 732 applies a bias to the absolute value of the DC voltage error to require the DC voltage error to be greater than a predetermined bias value before reducing the contribution of the second current demand and including the contribution of the first current demand. For example, the bias module 732 may set its output based on a predetermined bias value (e.g., 10V) subtracted from the absolute value of the DC voltage error. When the absolute value of the DC voltage error is less than the predetermined bias value, the initial current demand may be set to be equal to the second current demand due to the bias. The bias is associated with the saturation module (740), which is discussed further below.

[0160] Gain module 736 applies a predetermined gain value to the output of bias module 732. For example, gain module 736 sets its output based on the output of bias module 732 multiplied by the predetermined gain value, or sets its output to be equal to the output of bias module 732 multiplied by the predetermined gain value. For example, the predetermined gain value can be about 0.2 or another suitable value.

[0161] The saturation module 740 can impose limits on the output of the gain module 736. As used herein, the saturation module can impose a lower limit, an upper limit, both an upper and lower limit, or no limits. The upper and lower limits can be predetermined and / or can be updated based on various parameters. For example, in the case of the saturation module 740, the lower limit can be zero to re-enforce the bias applied by the bias module 732. The upper limit of the saturation module 740 can be 1 to limit the weighted value between 0 and 1, inclusive. The output of the saturation module 740 is a first weighted value used to weight the contribution of the first current demand.

[0162] Subtraction module 744 subtracts the output of saturation module 740 from a predetermined value (e.g., 1). The output of subtraction module 744 is a second weighted value used to weight the contribution of the second current demand. Multiplication module 748 multiplies the second current demand output by filter module 724 with the second weighted value output by subtraction module 744 to generate a third current demand. Multiplication module 752 multiplies the first current demand output by error control module 704 with the first weighted value output by saturation module 740 to generate a fourth current demand. Modules 728, 732, 736, 740, 744, 748, and 752 can be collectively referred to as weighting modules. Summation module 756 adds the third current demand to the fourth current demand to generate an initial current demand.

[0163] As discussed further below, the initial current requirement is multiplied by a sinusoidal reference signal synchronously generated from the AC input voltage. This provides a better power factor and minimizes harmonics in the AC input current because the load can absorb more sinusoidal current and power. The generation of the reference signal is also discussed below.

[0164] Figure 9 A functional block diagram including an example implementation of current demand module 612 is provided. Saturation module 804 can apply one or more limits to the initial current demand before it is input to notch filter module 808. Notch filter module 808 applies a notch filter to the initial current demand, and saturation module 812 can apply one or more limits to the initial current demand output by notch filter module 808. Although examples using saturation modules 804 and 812 are shown and discussed, one or both of saturation modules 804 and 812 can be omitted and / or replaced by other suitable types of signal processing. The application of the notch filter reduces harmonics while enabling a fast response to load changes.

[0165] For example, a notch filter can be a first-order or second-order polynomial notch filter. As an example only, a notch filter can be represented by the following second-order transfer function.

[0166]

[0167] Where b0, b1, b2, a0, a1, and a2 are filter coefficients, and z is the initial current requirement input to the notch filter module 808. One or more filter coefficients can be fixed predetermined values. For example, filter coefficients b0, b2, a0, and a2 can be fixed predetermined values. In various implementations, filter coefficient a0 can be 1 (a). In various implementations, filter coefficients b0, b2, a0, and / or a2 can be variable values.

[0168] The filter coefficient module 816 determines one or more filter coefficients (e.g., a1 and b1) for the notch filter based on the frequency of the AC input voltage. Since the reference signal is generated in sync with the AC input voltage, the frequency of the AC input voltage can be represented by the frequency of the reference signal. The frequency of the reference signal can be used as the supply frequency. Alternatively, the frequency of the AC input voltage can be measured and used as the supply frequency. For example, the notch filter can be approximately twice the supply frequency.

[0169] The filter coefficient module 816 can determine the filter coefficients using one or more lookup tables and / or functions that associate the supply frequency with the filter coefficients. For values ​​between entries in the lookup table, the filter coefficient module 816 can use interpolation to determine the filter coefficients. In various implementations, filter coefficients a1 and b1 can be the same value or can be determined using the same lookup table or function. Examples of such functions include second-order polynomial equations using predetermined coefficients to determine the filter coefficients (e.g., a1 and b1) based on the supply frequency.

[0170] As described above, saturation module 812 can apply one or more limits to the initial current demand output by notch filter module 808. Multiplication module 820 multiplies the output of saturation module 812 with a reference signal. Absolute value module 824 determines and outputs the absolute value (e.g., amplitude) of the output of multiplication module 820 to produce the final current demand. Alternatively, absolute value module 824 can be omitted, and the absolute value of the reference signal can be input to multiplication module 820. The use of absolute value makes the final current demand correspond to the rectified current. As discussed further below, the final current demand is used to control the switching of switch 320 based on a comparison with the measured current.

[0171] Figure 10 By based on Figure 6 and Figure 9 An example diagram showing how the generated final current requirement controls the current produced during switching. (See diagram below.) Figure 10 As shown, the current has a relatively sinusoidal shape. Figure 11 It is a response to a step change between heavy load and light load conditions by based on Figure 6 and Figure 9 Example graph of the measured DC bus voltage generated by the final current requirement used to control the switching.

[0172] and Figure 10 relatively, Figure 12 and Figure 13 These are example diagrams illustrating light-load and heavy-load conditions, respectively, where the switching current is controlled based on the second current demand output by the error control module 704. Figure 12 and Figure 13 As shown in the image, with Figure 10 Compared to the current, the current has a less sinusoidal (and possibly more square) shape.

[0173] Multiplying the second current demand output by the error control module 704 by the reference signal can produce a more sinusoidal current. For example, Figure 14 and Figure 15 These are example graphs illustrating light-load and heavy-load conditions, respectively, based on controlling the switching current by multiplying the reference signal by the second current demand output by filter module 724. Figure 14 and Figure 15 As shown, with Figure 10 Compared to the current, the current has a less sinusoidal (and possibly more triangular) shape.

[0174] Figure 16 This is an example graph showing the measured DC bus voltage generated in response to a step change between heavy and light load conditions, controlled by multiplying a reference signal by a second current demand output from error control module 704. Figure 11 Compared to the previous example, such control tends to produce slower response times, more overshoot, and / or more undershoot.

[0175] Figure 17 This is a flowchart depicting an example method for determining the final current requirement. Control begins at 904, where the error control module 704 determines the DC voltage error based on the difference between the desired DC bus voltage and the measured DC bus voltage. At 908, the error control module 704 uses, for example, PI control as discussed above, to determine the first current requirement based on the voltage bus error.

[0176] At 912, the absolute value module 728 determines the absolute value of the DC voltage error, and the bias module 732 applies a bias to the absolute value of the DC voltage error. For example, the bias module 732 may set its output based on subtracting a predetermined bias value (e.g., 10V) from the absolute value of the DC voltage error, or set its output to be equal to the absolute value of the DC voltage error minus the predetermined bias value (e.g., 10V). The gain module 736 applies a predetermined gain value to the output of the bias module 732, and the saturation module 740 may apply a limit to the output of the gain module 736. The output of the saturation module 740 corresponds to a first weighted value used to weight the contribution to the first current demand.

[0177] Still at 912, the subtraction module 744 determines a second weighting value for weighting the contribution of the second current demand. For example, the subtraction module 744 can set the second weighting value based on 1 minus the first weighting value, or set the second weighting value to be equal to 1 minus the first weighting value. Typically, due to bias, when the DC voltage error is less than a predetermined bias value, the first weighting value can be zero or approximately zero (making the second weighting value one or approximately one). As the DC voltage error increases beyond the predetermined bias value, the second weighting value can decrease toward zero and the first weighting value can increase toward one. Although the example uses a first weighting value and a second weighting value, as well as a first current demand and a second current demand, one or more additional filters can be applied to determine the second current demand from the first current demand. In such an example, more weighting values ​​can be used, or the first and second weighting values ​​can be applied to different combinations of current demands.

[0178] At 916, filter module 724 applies a filter to the first current demand to generate a second current demand. At 920, multiplication module 752 multiplies the first current demand by a first weighted value to generate a third current demand, and multiplication module 748 multiplies the second current demand by a second weighted value to generate a fourth current demand. Also at 920, summing module 756 sets an initial current demand based on the sum of the third and fourth current demands, or sets the initial current demand to be equal to the sum of the third and fourth current demands.

[0179] At 924, the saturation module 804 can apply an upper and / or lower limit to the initial current requirement. In various implementations, the application of the upper and / or lower limits can be omitted or replaced by one or more other types of signal processing. At 928, the filter coefficient module 816 determines the filter coefficients for the notch filter. The filter coefficient module 816 determines the filter coefficients based on the supplied power.

[0180] At 932, notch filter module 808 applies a notch filter with filter coefficients to the initial current demand. At 936, saturation module 812 can apply an upper and / or lower limit to the initial current demand output by notch filter module 808. In various implementations, the application of the upper and / or lower limits can be omitted or replaced by one or more other types of signal processing.

[0181] At 940, the multiplication module 820 sets the final current demand based on the initial current demand multiplied by the reference signal (e.g., the output of the saturation module 812), or sets the final current demand to be equal to the initial current demand multiplied by the reference signal (e.g., the output of the saturation module 812). At 944, the absolute value module 824 can determine the absolute value of the final current demand. At 948, the current control module 620 controls the switching of the switch 320 based on the final current demand and the measured current. As discussed further below, when the measured current becomes greater than the final current demand, the current control module 620 switches the switch 320 from ON to OFF. The current control module 620 keeps the switch 320 off for the (variable) desired off period and switches the switch 320 from OFF to ON when the desired off period has elapsed. Although this example is discussed further below, when the measured current becomes less than the final current requirement, the current control module 620 can alternatively switch 320 from off to on, keep switch 320 on for the (variable) desired on period, and switch 320 off once the desired on period has elapsed. The desired on period can be determined similarly to the desired off period discussed below.

[0182] Figure 18 This is a functional block diagram of an example implementation of the current control module 620. The current control module 620 controls the switching of the switch 320 based on a comparison between the final current demand and the measured current. The measured current can be measured using a current sensor 312.

[0183] When the measured current is less than the final current requirement, the comparison module 1004 sets the comparison signal to the first state. When the measured current is greater than the final current requirement, the comparison module 1004 sets the comparison signal to the second state.

[0184] The switch control module 1008 controls the switching of switch 320 based on a comparison between the measured current and the final current demand. For example, when the comparison signal transitions from a first state to a second state, the switch control module 1008 switches switch 320 to off (non-conducting). Then, the switch control module 1008 keeps switch 320 off for a desired off period. More specifically, the switch control module 1008 keeps switch 320 off until the off period is longer than the desired off period. The off period corresponds to the time period since the measured current last became greater than the final current demand.

[0185] When the comparison signal is in the second state, timer module 1012 increments the off period. More specifically, timer module 1012 increments the off period when switch 320 is off. Thus, the off period tracks the time elapsed since the last time switch control module 1008 switched switch 320 from on to off (i.e., the measured current became greater than the final current requirement). When switch control module 1008 switches switch 320 from off to on, timer module 1012 resets the off period.

[0186] When the off-time is greater than (or equal to) the desired off-time, the switch control module 1008 can switch 320 to the ON (conduct) state and keep switch 320 ON until the comparison signal is in the second state again. In various implementations, the switch control module 1008 can wait for or ensure that the measured current is less than the final current requirement before generating the output signal to turn on switch 320. Under relatively stable load conditions, the turning on of switch 320 can occur approximately at the beginning of the next predetermined switching cycle.

[0187] Predetermined switching period (t) p The predetermined switching frequency corresponds to a predetermined switching frequency. For example, the predetermined switching frequency could be approximately 200 kHz or another suitable switching frequency. The predetermined switching period corresponds to 1 divided by the predetermined switching frequency. The switch control module 1008 can control the switch 320 to be on (conducting) and off (not conducting) for different portions of each predetermined switching period. In various implementations, for example, a frequency module (not shown) can randomly change the predetermined switching frequency or the predetermined switching period based on the output of a random number generator.

[0188] The desired shutdown period module 1016 determines the desired shutdown period. Generally, for a boost converter, the desired shutdown period module 1016 can determine the desired shutdown period based on the input voltage, output voltage, and a predetermined switching cycle. The input voltage can correspond to the voltage input to the PFC circuit 300. For example, the absolute value module 1020 determines and outputs the absolute value (i.e., amplitude) of the AC input voltage measured by an AC input voltage sensor. The output of the absolute value module 1020 can be used as the input voltage. The output voltage can be a measured DC bus voltage. While an example of a sinusoidal AC input has been described, this application is also applicable to other types of inputs, including rectified inputs generated from the rectification of the AC input.

[0189] The desired shutdown period module 1016 can determine the desired shutdown period using either a function or a lookup table that associates the input and output voltages with the desired shutdown period for a given predetermined switching cycle. The desired shutdown period module 1016 can also determine the desired shutdown period using interpolation between the values ​​of the lookup table entries. As an example, for a boost converter (e.g., ...), Figure 4A (for the boost converter), the desired shutdown period module 1016 can set the desired shutdown period based on the following or set the desired shutdown period to be equal to the following:

[0190]

[0191] Where t p It is the scheduled switching cycle, V I It is the input voltage, and V O It is the output voltage.

[0192] The switch control module 1008 also compensates for the turn-on delay time and turn-off delay time of switch 320. This compensation can be omitted when the turn-on and turn-off delay times are negligible. The turn-on delay time corresponds to the time between the first time the switch control module 1008 generates an output signal to turn on switch 320 and the second time the switch 320 actually reaches the on (conducting) state in response. The turn-off delay time corresponds to the time between the first time the switch control module 1008 generates an output signal to turn off switch 320 and the second time the switch 320 actually reaches the off (non-conducting) state in response.

[0193] Considering the turn-on delay time, the switch control module 1008 should hypothetically generate an output signal to turn on the switch 320 before the desired turn-off period is reached. Due to the turn-off delay time, the switch control module 1008 should also hypothetically generate an output signal to turn on the switch 320 before the current becomes greater than the final current requirement.

[0194] The switch control module 1008 can adjust the desired off period based on the on delay time and the off delay time. For example, the switch control module 1008 can add the off delay time and subtract the on delay time relative to the desired off period. This (adjusted) desired off period is compared with the off period from the timer module 1012 to determine when to turn on the switch 320.

[0195] Other alternatives to this compensation are also feasible. For example, the switch control module 1008 can generate an output signal to turn off the switch 320 when the measured current is greater than a current threshold smaller than the final current requirement. The switch control module 1008 can also generate an output signal to turn on the switch 320 if the desired off period is reached earlier than the off period.

[0196] The delay determination module 1024 determines the turn-on delay time and the turn-off delay time. The monitoring module 1028 generates an turn-on / turn-off signal based on the voltage monitoring of the switch status signal from the switch monitoring circuit 328. For example, the monitoring module 1028 can set an turn-on / turn-off signal indicating whether switch 320 is on or off based on the switch status signal. Alternatively, the switch status signal can be used directly. In various implementations, for example, the turn-on delay time and the turn-off delay time can be set based on datasheet information related to the turn-on delay time and the turn-off delay time of switch 320. Further examples of the voltage across switch 320 are discussed in U.S. Provisional Application No. 0315-000926-US-PS1, filed April 15, 2016, entitled “Switch Actuation Measurement Circuit for Voltage Converter,” the entire contents of which are incorporated herein by reference. Although the monitoring module 1028 is shown as being implemented within the current control module 620, the monitoring module 1028 may be implemented outside the current control module 620 and outside the control module 220.

[0197] The delay determination module 1024 can set an on delay time or set a screenshot delay time equal to the time interval between the first time when the switch control module 1008 generates an output signal to turn on the switch 320 and the second time when the on / off signal responds to the output signal to turn on. Similarly, the delay determination module 1024 can set an off delay time or set a turn-off delay time equal to the time interval between the first time when the switch control module 1008 generates an output signal to turn off the switch 320 and the second time when the on / off signal responds to the output signal to turn off.

[0198] While an example is given of turning off switch 320 when the measured current becomes greater than the final current requirement and then keeping switch 320 off for the desired off period, switch control module 1008 may alternatively turn on switch 320 for the desired on period. More specifically, when the measured current drops below the final current requirement, switch control module 1008 may turn on switch 320, keep switch 320 on for the desired on period, and turn off switch 320 after the desired on period has elapsed since switch 320 was turned on. A desired on period module (not shown) determines the desired on period. Generally, for a boost converter, the desired on period module can determine the desired on period based on the input voltage, output voltage, and a predetermined switching cycle. The desired on period module can determine the desired on period using one of a function and a lookup table that associates the input and output voltages with the desired on period given a predetermined switching cycle. For values ​​between records in the lookup table, the desired on period module can use interpolation to determine the desired on period.

[0199] Figure 19 A functional block diagram of another example implementation of the current control module 620. Figure 19 This can be used to accommodate possible operations in discontinuous mode. Because discontinuous mode operation may cause an increase in switching frequency due to the switch's on-time being shorter than expected, possible operations in discontinuous mode can be considered. Discontinuous mode operation can refer to the measured current reaching zero during a predetermined switching cycle. During continuous mode operation, the measured current does not reach zero. For example, as the input and / or output voltage changes, the operation can vary between continuous and discontinuous mode operation. By way of example only, discontinuous mode operation can occur near the zero-crossing point.

[0200] Instead of determining the desired shutdown period based on input voltage, output voltage, and a predetermined switching cycle (e.g., ... Figure 18 In the example, the expected shutdown period module 1016 can determine the expected shutdown period based on a predetermined switching cycle and an expected turn-on period. The expected shutdown period module 1016 can determine the expected shutdown period using a function or lookup table that associates the predetermined switching cycle and expected turn-on period with the expected shutdown period. For values ​​between entries in the lookup table, the expected shutdown period module 1016 can use interpolation to determine the expected shutdown period. For example, the expected shutdown period module 1016 can set the expected shutdown period based on the following or set the expected shutdown period to be equal to the following:

[0201] t p -t ON_EXP , where t p It is the scheduled switching cycle, and t ON_EXP This is the expected connection period.

[0202] The expected connection period module 1104 can set the expected connection period based on or equal to the smaller of the expected discontinuous mode connection period and the expected continuous mode connection period, or set the expected connection period to be equal to the smaller one. In other words, when the expected discontinuous mode connection period is less than the expected continuous mode connection period, the expected connection period module 1104 can set the expected connection period based on the expected discontinuous mode connection period or set the expected connection period to be equal to the expected discontinuous mode connection period. When the expected continuous mode connection period is less than or equal to the expected discontinuous mode connection period, the expected connection period module 1104 can set the expected connection period based on the expected continuous mode connection period or set the expected connection period to be equal to the expected continuous mode connection period.

[0203] The discontinuous mode turn-on period module 1108 determines the expected discontinuous mode turn-on period based on the final current demand, the inductance (L) of inductor 308, and the input voltage. The discontinuous mode turn-on period module 1108 uses a function or lookup table that correlates the final current demand, inductance, and input voltage with the expected discontinuous mode turn-on period to determine the expected discontinuous mode turn-on period. For values ​​between entries in the lookup table, the discontinuous mode turn-on period module 1108 can use interpolation to determine the expected discontinuous mode turn-on period. For example, the discontinuous mode turn-on period module 1108 can set the expected discontinuous mode turn-on period based on the following or set the expected discontinuous mode turn-on period to be equal to the following:

[0204]

[0205] Where v I is the input voltage, IDem is the final current requirement, and L is the inductance of inductor 308.

[0206] The continuous mode on-time module 1102 determines the expected continuous mode on-time based on a predetermined switching cycle, output voltage, and input voltage. The continuous mode on-time module 1102 uses a function or lookup table that associates the predetermined switching cycle, output voltage, and input voltage with the expected continuous mode on-time to determine the expected continuous mode on-time. For values ​​between entries in the lookup table, the continuous mode on-time module 1102 can use interpolation to determine the expected continuous mode on-time. For example, the continuous mode on-time module 1102 can set the desired continuous mode on-time based on the following, or set the desired continuous mode on-time to be equal to the following:

[0207]

[0208] Where t pIt is the scheduled switching cycle, v O It is the output voltage, and v I It is the input voltage.

[0209] An alternative scheme for determining the expected on-time will now be described. The maximum value module 1116 determines the maximum current (IMax). The maximum current corresponds to the largest measured current expected starting from zero current, given the expected continuous-mode on-time and the final current requirement. The maximum value module 1116 determines the maximum current based on the expected continuous-mode on-time, the input voltage, and the inductance of inductor 308. The maximum value module 1116 determines the maximum current using a function or lookup table that correlates the expected continuous-mode on-time, the input voltage, and the inductance with the maximum current. For values ​​between entries in the lookup table, the maximum module 1116 can use interpolation to determine the maximum current. For example, the maximum module 1116 can set the maximum current period based on or set the maximum current period to be equal to the following:

[0210]

[0211] Where t ON_Cont This is the expected continuous mode connection period, v I It is the input voltage, and L is the inductance of inductor 308.

[0212] When the final current demand is less than the maximum current, discontinuous mode operation occurs, and the expected on-time module 1104 can set the expected on-time based on the following or set the expected on-time to be equal to the following:

[0213]

[0214] Where t ON_Cont Here, Iem is the expected continuous mode on-time, Imax is the final current demand, and Imax is the maximum current. Alternatively, when discontinuous mode operation occurs (i.e., when the final current demand is less than the maximum current), the expected on-time module 1104 can set the expected on-time based on the following or set the expected on-time to be equal to the following:

[0215]

[0216] Where IDem is the final current requirement, L is the inductance of inductor 308, and v O It is the output voltage, and v I This is the input voltage. When the final current demand is greater than or equal to the maximum current, the expected turn-on period module 1104 can be based on or equal to the expected continuous mode turn-on period (t). ON_ContTo set the expected connection period or to set the expected connection period to be equal to the expected continuous mode connection period (t) ON_Cont ).

[0217] Although examples of boost converters have already been described Figure 18 and Figure 19 However, the concept of variable off-time also applies to buck converters. For example, for buck converters (e.g., Figure 3B and Figure 4B (for the buck converter), the desired shutdown period module 1016 can set the desired shutdown period based on the following or set the desired shutdown period to be equal to the following:

[0218]

[0219] Where t p It is the scheduled switching cycle, v I It is the input voltage, and v O It refers to the output voltage. For discontinuous current, for information about... Figure 19 The similar corrections described can be applied to examples of buck converters.

[0220] Turning switch 320 on for a predetermined fixed on period during each predetermined switching cycle, or turning switch 320 off for a predetermined fixed off period during each predetermined switching cycle, may result in undesirable current ripple, for example, when the input voltage to output voltage ratio is low. For example, the amplitude of the current ripple may increase and / or the frequency of the current ripple may differ from the predetermined switching frequency. Furthermore, switching based on a comparison of measured current with the final current demand using a fixed predetermined switching cycle may generate non-periodic current ripple. Figure 20 and Figure 21 Includes example graphs of current versus time and shows an example of non-periodic current ripple.

[0221] Determining the desired off period and keeping switch 320 off during the desired off period provides a more periodic current ripple with approximately a predetermined switching frequency. Figure 22 , Figure 23 and Figure 24 Included in the basis Figure 18 Example graphs showing the changes in input voltage, output voltage, and current versus time under load conditions that determine the desired off-time period. Figure 25 Including those based on Figure 19 The example chart illustrates the time versus current generated by determining the desired off-time. This can provide more stable operation than using predetermined fixed on or off periods and provides more stable operation than using predetermined switching cycles.

[0222] Figure 26This includes a flowchart depicting an example method for determining the desired off-time of switch 320 and controlling switch 320 based on the desired off-time. Control begins at 1204, where switch control module 1008 determines whether switch 320 is off (non-conductive). If 1204 is true, control transfers to 1228, discussed further below. If 1204 is false, control continues at 1208.

[0223] At position 1208, the desired shutdown period module 1016 determines the desired shutdown period. The desired shutdown period module 1016 can be configured as described above relative to... Figure 20 and Figure 21 The desired off period is determined as described in the example. At 1212, the switch control module 1008 can adjust the desired off period based on the turn-on delay time and the turn-off delay time. For example, the switch control module 1008 can add the desired off period to the turn-on delay time and subtract the turn-off delay time.

[0224] At 1216, the comparison module 1004 can determine whether the measured current is greater than the final current requirement. The determination of the final current requirement has been discussed above. If 1216 is false, the timer module 1012 resets the shutdown period, and at 1220, the switch control module 1008 keeps switch 320 off, and control ends. If 1216 is true, control continues at 1224.

[0225] When the measured current exceeds the final current requirement, the switch control module 1008 generates an output signal at 1224 to turn off switch 320. At 1228, the switch control module 1008 can determine whether the off-time of switch 320 is longer than the expected off-time. If 1228 is false, the switch control module 1008 keeps switch 320 off at 1232, and the control ends. If 1228 is true, the switch control module 1008 can generate an output signal at 1236 to turn on switch 320, and the control ends. In various implementations, the switch control module 1008 can wait or ensure that the measured current is less than the final current requirement before generating the output signal at 1236 to turn on switch 320. When the control is shown as finished, Figure 26 The example shows a control loop and the control can return 1204 for the next control loop.

[0226] Figure 27A and Figure 27B Together, this includes a functional block diagram of the example reference signal generation module 616. Refer to [link / reference] now. Figure 27AThe filter module 1304 applies a filter to the AC input voltage measured using an AC line voltage sensor to produce a filtered AC input voltage. By way of example only, the filter module 1304 may apply a first-order low-pass filter, a second-order low-pass filter, or another suitable type of filter.

[0227] Comparison module 1308 compares the filtered AC input voltage with a first predetermined voltage less than 0 (zero) V. When the filtered AC input voltage changes from less than the first predetermined voltage to greater than the first predetermined voltage, comparison module 1308 transitions the stored signal from a second state to a first state. By way of example only, the first predetermined voltage can be approximately -50V or another suitable voltage less than zero.

[0228] When the stored signal transitions from the second state to the first state, the storage module 1312 stores the filtered AC input voltage and the current time. The stored filtered AC input voltage and storage time are used to determine the zero-crossing point of the AC input voltage. For example, the current time can be tracked by a clock.

[0229] The comparison module 1308 also compares the filtered AC input voltage with a second predetermined voltage greater than 0V. When the filtered AC input voltage changes from less than the second predetermined voltage to greater than the second predetermined voltage, the comparison module 1308 transitions the interpolation signal from a second state to a first state. By way of example only, the second predetermined voltage could be +50V or another suitable voltage greater than 0V. While the example of the first and second predetermined voltages is symmetrical about 0V (e.g., + / -50V), asymmetrical first and second predetermined voltages can be used, or the first and second predetermined voltages can be symmetrical about voltages other than 0V.

[0230] When the interpolated signal transitions from the second state to the first state, the zero-crossing module 1316 determines the AC line zero-crossing point (e.g., time) based on the filtered AC input voltage at that (current) time, the current time, the stored time, and the stored filtered AC input voltage. The stored time and the stored filtered AC input voltage are provided by the storage module 1312. For example, the zero-crossing module 1316 can determine the AC line zero-crossing point using linear interpolation based on the filtered AC input voltage, the current time, the stored time, and the stored filtered AC input voltage. The AC line zero-crossing point corresponds to the time when the filtered AC input voltage crosses zero as it increases from a first predetermined voltage to a second predetermined voltage. The AC line zero-crossing point can be determined for each rise in the AC voltage across zero.

[0231] Figure 28This includes an example graph of the filtered AC input voltage versus time. In this example, for illustrative purposes, the input AC voltage (and then the filtered AC input voltage) is not a pure sine wave. The first voltage, the time of the first voltage (first time), and the second voltage and the time of the second voltage (second time) can be used to determine the zero-crossing point via linear interpolation.

[0232] Come back for reference Figure 27A The frequency module 1320 determines the supply frequency. As discussed above, the filter coefficient module 816 uses the supply frequency to determine the filter coefficients of the notch filter. The supply frequency corresponds to the frequency of the AC input voltage. For example, the frequency module 1320 can determine the supply frequency based on two or more values ​​of the filtered AC input voltage. For example, the frequency module 1320 can determine the supply frequency based on the time interval between two consecutive peaks or two consecutive zero crossings of the filtered AC input voltage. Alternatively, the frequency module 1320 can determine the supply frequency based on a reference signal.

[0233] The filtering performed by filter module 1304 delays the filtered AC input voltage relative to the AC input voltage. Filter correction module 1324 determines the filter correction for this delay based on the supply frequency. For example, filter correction module 1324 can use a function or lookup table that associates the supply frequency with the filter correction to determine the filter correction. For values ​​between entries in the lookup table, filter correction module 1324 can use interpolation to determine the filter correction. Figure 29 Example diagrams including filter correction and supply frequency.

[0234] Error module 1328 determines the error based on the difference between the AC line zero-crossing point and the reference signal zero-crossing point. Error module 1328 can also adjust the filter correction error. For example, error module 1328 can set the error based on the AC line zero-crossing point plus the filter correction minus the reference signal zero-crossing point, or set the error to be equal to the AC line zero-crossing point plus the filter correction minus the reference signal zero-crossing point. In various implementations, the AC line zero-crossing point can be adjusted based on the filter correction (e.g., summed with the filter correction), and error module 1328 can set the error based on the (adjusted) AC line zero-crossing point minus the reference signal zero-crossing point, or set the error to be equal to the (adjusted) AC line zero-crossing point minus the reference signal zero-crossing point.

[0235] Phase adjustment module 1332 determines the phase adjustment of the sine wave used to generate the reference signal based on the error. For example, phase adjustment module 1332 can determine the phase adjustment using one of a function that associates the error with the phase adjustment and a lookup table. For the values ​​between the entries in the lookup table, phase adjustment module 1332 can use interpolation to determine the phase adjustment. When the error is greater than a predetermined period, for example, approximately one period of the supply frequency, phase adjustment module 1332 can treat the error as zero and keep the phase adjustment unchanged.

[0236] The RMS (Root Mean Square) module 1336 determines the RMS voltage of the AC input voltage based on the supply frequency and the AC input voltage. For example, the RMS module 1336 can determine the RMS voltage using one of the functions that associates the AC input voltage and the supply frequency with the RMS voltage. As an example, the RMS module 1336 can determine the RMS voltage by determining the average of the squares of the AC input voltage obtained over one period (as indicated by the supply frequency) and setting the RMS voltage based on the square root of the average. The RMS module 1336 can also multiply the RMS voltage by the square root of 2 to obtain the peak voltage. While examples of determining the RMS voltage based on the AC input voltage are provided, a filtered AC voltage can be used instead of the AC input voltage. As discussed further below, the RMS voltage (or peak voltage) can be used to scale a reference signal such that the voltage of the reference signal corresponds to the AC input voltage.

[0237] Now refer to Figure 27B The sine generator module 1350 generates a sinusoidal reference signal. The sine generator module 1350 can generate a sinusoidal reference signal to form a sine wave that varies between +1 and -1 over time and has a frequency equal to the frequency of the AC input voltage. However, the sine generator module 1350 adjusts the sinusoidal reference signal based on phase adjustment so that the zero-crossing point of the reference signal is aligned with the zero-crossing point of the AC input voltage. For example, as combined with the following... Figure 27D As described in 1368, 1370 and 1372, the sine generator module 1350 can generate a sine reference signal.

[0238] Reference module 1354 generates a reference signal based on a sinusoidal reference signal and an RMS voltage. For example, reference module 1354 can set the reference signal based on the value of a sinusoidal reference signal multiplied by the peak voltage of the RMS voltage, or set the reference signal to be equal to the value of a sinusoidal reference signal multiplied by the peak voltage of the RMS voltage. Therefore, the reference signal varies with time, having a voltage corresponding to the AC input voltage and a frequency equal to the AC input voltage.

[0239] Comparison module 1358 compares a reference signal with a third predetermined voltage greater than 0 (zero) V. When the reference signal changes from being greater than the third predetermined voltage to being less than the third predetermined voltage, comparison module 1358 transitions the stored signal from a second state to a first state. By way of example only, the third predetermined voltage can be approximately +50 V or another suitable voltage greater than 0 V. The third predetermined voltage can be the same as the second predetermined voltage.

[0240] When the stored signal transitions from the second state to the first state, the storage module 1362 stores the voltage of the reference signal and the current time. The stored voltage and time of the reference signal are used to determine the zero-crossing point of the reference signal.

[0241] Comparison module 1358 also compares the reference signal with a fourth predetermined voltage less than 0V. When the reference signal transitions from greater than the fourth predetermined voltage to less than the fourth predetermined voltage, comparison module 1358 transitions the interpolated signal from a second state to a first state. By way of example only, the fourth predetermined voltage could be approximately -50V or another suitable voltage less than 0V. While the examples of the third and fourth predetermined voltages are symmetrical about 0V (e.g., + / -50V), asymmetrical third and fourth predetermined voltages can be used. The fourth predetermined voltage can be the same as the first predetermined voltage.

[0242] When the interpolated signal transitions from the second state to the first state, the zero-crossing module 1366 determines the zero-crossing point (e.g., time) of the reference signal based on the reference signal (voltage) at that (current) time, the current time, the stored time, and the stored voltage of the reference signal. The stored time and the stored voltage of the reference signal are provided by the storage module 1362. For example, the zero-crossing module 1366 can determine the zero-crossing point of the reference signal using linear interpolation based on the voltage of the reference signal, the current time, the stored time, and the stored voltage of the reference signal. The zero-crossing point of the reference signal corresponds to the time it takes for the reference signal to cross zero V (volts) as it decreases from a third predetermined voltage to a fourth predetermined voltage. The zero-crossing point of the reference signal can be determined for each drop of the reference signal across zero.

[0243] Figure 30 Example graphs of voltage versus time for a reference signal are provided. The first voltage and time (first time) of the reference signal, and the second voltage and time (second time) of the reference signal can be used to determine the zero-crossing point of the reference signal via linear interpolation. While an example of using a reference signal to determine its zero-crossing point has been discussed, a sinusoidal reference signal can be used similarly.

[0244] As discussed above, the reference signal zero-crossing is used in conjunction with the AC line zero-crossing to determine phase correction. Since the AC line zero-crossing is determined based on the rising portion of the AC input voltage and the reference signal zero-crossing is determined based on the falling portion of the reference signal, each reference signal zero-crossing should be approximately 180 degrees (1 / 2 cycle) out of phase with the AC line zero-crossing that occurs before and after the reference signal zero-crossing.

[0245] The phase adjustment module 1332 can take this phase difference into account when generating the phase adjustment. As an example only, each AC line zero-crossing point can be adjusted based on a time period corresponding to half the cycle of the supply frequency before being used by the error module 1328. For example, the time period corresponding to half the cycle of the supply frequency can be added to each AC line zero-crossing point before being used by the error module 1328.

[0246] An alternative method for generating a reference signal is described in U.S. Patent No. 8,264,860, published September 11, 2012, the entire contents of which are incorporated herein by reference. However, generating a reference signal as described herein can be performed more slowly and consumes fewer computational resources. The generated reference signal as described herein also presents a better reference signal when the AC input voltage is distorted. Filtering provided by filter module 1304 provides additional robustness. As mentioned above, filtering introduces a delay, but this delay is compensated for by filter module 1324.

[0247] Figure 27C and Figure 27D Together, a functional block diagram of the example reference signal generation module 616 is included. Figure 27C Including with Figure 27A The components are similar to those in the error module 1328. However, the zero-crossing point of the reference signal input to the error module 1328 is determined differently.

[0248] Now refer to Figure 27D The base module 1368 determines the base reference (signal) angle based on the supply frequency. The base reference angle corresponds to the angle of the reference signal (e.g., between 0 and 360 degrees, corresponding to one cycle of the reference signal). For example, the base module 1368 can mathematically integrate the supply frequency for each control loop. This mathematical integration produces a change in the base reference angle. The base module 1368 updates the base reference angle for each control loop by adding the change determined for that control loop to the base reference angle from the previous control loop. In various implementations, the base module 1368 can limit the base reference angle between 0 and a predetermined maximum value (e.g., 360 degrees), falling back to 0 when the base reference angle becomes greater than the predetermined maximum value. This can be done, for example, using a modulo function.

[0249] The reference angle module 1370 determines the reference signal angle based on the phase adjustment and the base reference angle. For example, the reference angle module 1370 can set the reference signal angle based on the phase adjustment plus the base reference angle, or set the reference signal angle to be equal to the phase adjustment plus the base reference angle.

[0250] The sine module 1372 determines the angle of the sinusoidal reference signal as a reference signal angle that is sinusoidal (a function). For example, the sinusoidal reference signal angle is based on the reference signal angle varying between +1 and -1. The reference module 1374 generates a reference signal based on the sinusoidal reference signal angle and the RMS voltage. For example, the reference module 1374 can set the reference signal based on the value of the sinusoidal reference signal angle (which is the peak voltage multiplied by the RMS voltage) or set the reference signal to be equal to the value of the sinusoidal reference signal angle (which is the peak voltage multiplied by the RMS voltage). Therefore, the reference signal varies with time, having a voltage corresponding to the AC input voltage and a frequency equal to the AC input voltage.

[0251] Comparison module 1376 compares a reference signal with a first predetermined angle. When the angle of the reference signal changes from less than the first predetermined angle to greater than the first predetermined angle, comparison module 1376 transitions the stored signal from a second state to a first state. By way of example only, the first predetermined angle may be approximately 150 degrees or another suitable angle (e.g., 180 degrees) before the expected zero-crossing point of the reference signal.

[0252] When the stored signal transitions from the second state to the first state, the storage module 1378 stores the reference signal angle and the current time. The stored reference angle and stored time are used to determine the zero-crossing point of the reference signal.

[0253] Comparison module 1376 also compares the reference angle with a second predetermined angle. When the reference angle changes from being less than the second predetermined angle to being greater than the second predetermined angle, comparison module 1376 transitions the interpolated signal from a second state to a first state. By way of example only, the second predetermined angle could be approximately 210 degrees or another suitable angle (e.g., 180 degrees) after the expected zero-crossing point of the reference signal. While examples of a first and second predetermined angles symmetrical about 180 degrees are provided, other asymmetrical predetermined angles and other predetermined angles can be used.

[0254] When the interpolated signal transitions from the second state to the first state, the zero-crossing module 1380 determines the reference signal zero-crossing point (e.g., time) based on the reference signal angle at the current time, the current time, the stored time, and the stored reference signal angle. The stored time and the stored reference signal angle are provided by the storage module 1378. For example, the zero-crossing module 1380 can determine the reference signal zero-crossing point using linear interpolation based on the reference signal angle, the current time, the stored time, and the stored reference signal angle. The reference signal zero-crossing point corresponds to the time it takes for the reference signal to cross zero V (volts) as it decreases. The reference signal zero-crossing point can be determined for each decrease in the reference signal's range across zero.

[0255] Figure 27E and Figure 27F Together, this includes a functional block diagram of the example reference signal generation module 616. Figure 27E and Figure 27F In the example, the zero-crossing point of the AC line is used to determine the expected reference angle. Figure 27E and Figure 27F In the example, the zero-crossing point of the reference signal is uncertain.

[0256] Reference Figure 27F The anticipating module 1386 determines the expected reference signal angle. The expected reference signal angle at a given time corresponds to the expected value of the reference signal angle at that time. The anticipating module 1386 determines the expected reference signal angle based on the AC line zero-crossing point and the supply frequency. For example, the anticipating module 1386 can set the expected reference signal angle to zero at each AC line zero-crossing point. The anticipating module 1386 can mathematically integrate the supply frequency of each control loop. The mathematical integration produces a change in the expected reference signal angle. The anticipating module 1386 can update the expected reference signal angle of each control loop by adding the change determined for that control loop to the expected reference signal angle from the previous control loop. In various implementations, the anticipating module 1386 can limit the expected reference signal angle between 0 and a predetermined maximum value (e.g., 360 degrees), and fall back to 0 when the expected reference signal angle becomes greater than the predetermined maximum value. For example, this can be done using a modulo function. The expected reference signal angle is further discussed below.

[0257] The reference angle module 1388 determines the base reference (signal) angle based on the adjusted supply frequency. The following is relative to... Figure 27EThe generation of the adjusted supply frequency is further discussed. For example, the reference angle module 1388 can determine the change in the reference signal angle based on the time interval between consecutive determinations of the base reference signal angle and the adjusted supply frequency. For example, the reference angle module 1388 can mathematically integrate the adjusted supply frequency for each control loop. The mathematical integration produces a change in the base reference angle. The reference angle module 1388 can update the base reference angle of each control loop by adding the change determined for that control loop to the base reference angle from the previous control loop. In various implementations, the reference angle module 1388 can limit the base reference angle between 0 and a predetermined maximum value (e.g., 360 degrees), and back to 0 when the base reference angle becomes greater than the predetermined maximum value. For example, this can be done using a modulo function. The sine module 1372 and the reference module 1374 have been discussed above, and the reference signal is generated using the sine module 1372 and the reference module 1374.

[0258] Reference Figure 27E Error module 1390 determines the angle error based on filter correction (from filter correction module 1324), the expected reference signal angle (determined by expected module 1386), and the reference angle (determined by reference angle module 1388). By way of example only, error module 1390 can set the angle error based on the expected reference angle minus the reference angle plus the filter correction, or set the angle error to be equal to the expected reference angle minus the reference angle plus the filter correction.

[0259] Frequency adjustment module 1392 determines the frequency adjustment based on the error. For example, frequency adjustment module 1392 can increase the frequency adjustment as the error increases and decrease the frequency adjustment as the error decreases. Adjustment module 1394 adjusts the supply frequency based on the frequency adjustment to determine the adjusted supply frequency. For example, adjustment module 1394 can set the adjusted supply frequency based on the supply frequency plus the frequency adjustment, or adjust the adjusted supply frequency to be equal to the supply frequency plus the frequency adjustment. Based on the above, the reference signal will be adjusted to correspond to the AC line voltage in frequency and phase.

[0260] Figure 31 It is a description, for example, based on Figures 27A to 27BThe flowchart illustrates an example method for determining the zero-crossing point of an AC line. Control begins at 1404, where filter module 1304 filters the AC input voltage to produce a filtered AC input voltage. For example only, filter module 1304 could apply a low-pass filter. At 1408, comparison module 1308 determines whether the filtered AC input voltage has transitioned from less than a first predetermined voltage (e.g., -50V) to greater than a first predetermined voltage. If 1408 is true, storage module 1312 stores the filtered AC input voltage and the current time at 1412, and control ends. If 1408 is false, control transitions to 1416.

[0261] At 1416, the comparison module 1308 determines whether the filtered AC input voltage has transitioned from less than a second predetermined voltage (e.g., +50V) to greater than a second predetermined voltage. If 1416 is true, then at 1420, the zero-crossing module 1316 uses linear interpolation based on the stored filtered AC input voltage, the current filtered AC input voltage, the stored time, and the current time to determine the AC line zero-crossing point (as the filtered AC input voltage increases from the first predetermined voltage toward the second predetermined voltage). Then, control ends. If 1416 is false, control ends. Although control is shown as ended, Figure 31 The example illustrates a control loop, and control can return to 1404 for the next control loop. Furthermore, while an example of interpolation once the filtered AC voltage transitions to a value greater than the second predetermined voltage has been described, the zero-crossing module 1316 can perform interpolation based on the current filtered AC voltage of each control loop and determine the AC line zero-crossing point based on the interpolation at the time when the filtered AC input voltage has transitioned to a value greater than the second predetermined voltage.

[0262] Figure 32 It is a description, for example, based on Figures 27A to 27B The flowchart illustrates an example method for determining the zero-crossing point of a reference signal. Control begins at 1504, where reference module 1354 generates a reference signal (voltage) based on multiplying the RMS voltage by a sinusoidal reference signal (value). At 1508, comparison module 1358 determines whether the reference signal voltage has transitioned from being greater than a third predetermined voltage (e.g., +50V) to being less than a third predetermined voltage. If 1508 is true, storage module 1362 stores the reference signal voltage and the current time at 1512, and control ends. If 1508 is false, control transitions to 1516.

[0263] At 1516, comparison module 1358 determines whether the voltage of the reference signal has changed from greater than the fourth predetermined voltage (e.g., -50V) to less than the fourth predetermined voltage. If 1516 is true, then at 1520, zero-crossing module 1366 uses linear interpolation based on the stored reference signal voltage, the current voltage of the reference signal, the stored time, and the current time to determine the zero-crossing point of the reference signal (since the reference signal decreases from the third predetermined voltage toward the fourth predetermined voltage). Then, control ends. If 1516 is false, control ends. Although control is shown as ended, Figure 32 The example shows a control loop, and control can return to 1504 for the next control loop. Figure 32 Examples can be compared with Figure 31 The examples are executed in parallel. Furthermore, while an example of interpolation once the voltage of the reference signal transitions to less than a fourth predetermined voltage has been described, the zero-crossing module 1366 can perform interpolation based on the current voltage of the reference signal in each control loop, and determine the zero-crossing point of the reference signal based on the interpolation at the time when the current voltage has transitioned to less than the fourth predetermined voltage.

[0264] Figure 33 It is a description, for example, based on Figures 27A to 27B The flowchart illustrates an example method for generating a reference signal. Control begins at 1604, where the sine generator module 1350 can determine whether the zero-crossing module 1366 has just determined the zero-crossing point of the reference signal. For example, the zero-crossing module 1366 can send such a determination signal to the sine generator module 1350, or the sine generator module 1350 can determine that the zero-crossing module 1366 has determined the zero-crossing point of the reference signal when the zero-crossing point changes. If 1604 is false, control can proceed to 1628, which is discussed further below. If 1604 is true, control can continue at 1612.

[0265] At 1612, control can make one or more adjustments to accommodate approximately half a cycle (e.g., 1 / supply frequency) difference between the AC line zero-crossing point and the reference signal zero-crossing point. For example, zero-crossing module 1316 can add half a cycle of the AC input voltage to the AC line zero-crossing point, or zero-crossing module 1366 can subtract half a cycle of the AC input voltage from the reference signal zero-crossing point. At 1616, filter correction module 1324 determines filter correction based on the supply frequency. Filter correction corresponds to the delay time imposed by over-filter module 1304.

[0266] At 1620, error module 1328 determines the error between the (previously determined) AC line zero-crossing point and the (just determined) reference signal zero-crossing point. For example, error module 1328 can set the error based on the AC line zero-crossing point plus filter correction and minus the reference signal zero-crossing point, or set the error to be equal to the AC line zero-crossing point plus filter correction and minus the reference signal zero-crossing point. At 1624, phase adjustment module 1332 updates the phase adjustment based on the error. For example, phase adjustment module 1332 can use a function or lookup table that associates the error with the phase adjustment to determine the phase adjustment.

[0267] At 1628, the sine generator module 1350 generates the next value of the sinusoidal reference signal based on phase adjustment, which is used to generate the sine wave for the next cycle. At 1632, the reference module 1354 generates the next voltage of the reference signal based on the sinusoidal reference signal and the RMS voltage (of the AC line). For example, the reference module 1354 can set the voltage of the reference signal based on the value of the sinusoidal reference signal multiplied by the peak value of the RMS voltage, or set the voltage of the reference signal to be equal to the value of the sinusoidal reference signal multiplied by the peak value of the RMS voltage. For example, at 1628, the RMS module 1336 determines the RMS voltage based on the AC input voltage. The RMS module 1336 can set the peak voltage based on the RMS voltage multiplied by the square root of 2, or set the peak voltage to be equal to the RMS voltage multiplied by the square root of 2.

[0268] Although the control is shown as ended, Figure 33 The example shows a control loop, and the control can return to 1604 for use in the next control loop. Figure 33 Examples can be compared with Figure 31 and Figure 32 The examples are executed in parallel. Furthermore, while the example updates the phase adjustment when the reference signal zero-crossing is determined, when the AC line zero-crossing is determined, the AC line zero-crossing and the previous reference signal zero-crossing (from approximately half of an earlier cycle) can be used to additionally or alternatively update the phase adjustment. Although combined... Figures 27A to 27B Examples discussed Figures 31 to 33 However, similar concepts apply to Figures 27C to 27D and Figures 27E to 27F Examples.

[0269] This disclosure may also have the following configurations:

[0270] 1. A power factor correction (PFC) system, comprising:

[0271] An error control module determines the first current requirement based on the difference between the desired DC voltage and the measured DC voltage;

[0272] A filter module that applies a filter to the first current demand to generate a second current demand;

[0273] The weighting module (i) determines a first weighting value and a second weighting value for the first current demand and the second current demand respectively based on the difference, (ii) determines a third current demand based on the first current demand and the first weighting value, and (iii) determines a fourth current demand based on the second current demand and the second weighting value.

[0274] A current demand module determines a final current demand based on the third current demand and the fourth current demand; and

[0275] The current control module controls the switching of the PFC device based on the final current requirement.

[0276] 2. The PFC system according to Scheme 1 further includes: a summation module for determining the fifth current demand based on the sum of the third current demand and the fourth current demand.

[0277] Specifically, the current demand module applies a notch filter to the fifth current demand and determines the final current demand based on the output of the notch filter.

[0278] 3. The PFC system according to Scheme 2, wherein the current demand module sets the final current demand based on the output of the notch filter multiplied by the value of a sinusoidal reference signal, the sinusoidal reference signal being generated to be synchronized with the input AC voltage in phase and frequency.

[0279] 4. The PFC system according to Scheme 2 further includes a filter coefficient module, which sets the filter coefficients of the notch filter based on the frequency of the input AC voltage.

[0280] 5. The PFC system according to Scheme 1, wherein when the difference is less than a predetermined value, the weighting module sets the third current demand to zero.

[0281] 6. The PFC system according to Scheme 5, wherein when the difference is less than the predetermined value, the weighting module further sets the fourth current demand to be equal to the second current demand.

[0282] 7. The PFC system according to Scheme 5, wherein when the difference is greater than the predetermined value, the weighting module increases the first weighting value and decreases the second weighting value.

[0283] 8. The PFC system according to Scheme 5, wherein when the difference is greater than the predetermined value, the weighting module increases the first weighting value as the difference increases, and decreases the second weighting value as the difference increases.

[0284] 9. The PFC system according to Scheme 1, wherein the weighting module:

[0285] The third current requirement is set based on the product of the first current requirement and the first weighted value; and

[0286] The fourth current requirement is set by multiplying the second current requirement by the second weighted value.

[0287] 10. The PFC system according to Scheme 1, wherein the filter module applies a low-pass filter to the first current demand to generate the second current demand.

[0288] 11. A power factor correction (PFC) method, comprising:

[0289] The first current requirement is determined based on the difference between the expected DC voltage and the measured DC voltage.

[0290] Apply the filter to the first current demand to generate the second current demand;

[0291] Based on the difference, a first weighted value and a second weighted value are determined for the first current demand and the second current demand, respectively;

[0292] The third current requirement is determined based on the first current requirement and the first weighted value;

[0293] The fourth current requirement is determined based on the second current requirement and the second weighting value;

[0294] The final current requirement is determined based on the third current requirement and the fourth current requirement; and

[0295] The switching of the PFC device is controlled based on the final current requirement.

[0296] 12. The PFC method according to Scheme 11 further includes:

[0297] The fifth current demand is determined based on the sum of the third and fourth current demands; and

[0298] Apply a notch filter to the fifth current requirement.

[0299] Determining the final current requirement includes: determining the final current requirement based on the output of the notch filter.

[0300] 13. The PFC method according to Scheme 12, wherein determining the final current requirement includes: setting the final current requirement based on multiplying the output of the notch filter by the value of a sinusoidal reference signal, the sinusoidal reference signal being generated to be synchronized with the input AC voltage in phase and frequency.

[0301] 14. The PFC method according to Scheme 12 further includes: setting the filter coefficients of the notch filter based on the frequency of the input AC voltage.

[0302] 15. The PFC method according to Scheme 11 further includes: setting the third current requirement to zero when the difference is less than a predetermined value.

[0303] 16. The PFC method according to Scheme 15 further includes: when the difference is less than the predetermined value, setting the fourth current demand to be equal to the second current demand.

[0304] 17. The PFC method according to Scheme 15 further includes: when the difference is greater than the predetermined value, increasing the first weighting value and decreasing the second weighting value.

[0305] 18. The PFC method according to Scheme 15 further includes: when the difference is greater than the predetermined value, increasing the first weighting value as the difference increases, and decreasing the second weighting value as the difference increases.

[0306] 19. The PFC method according to Scheme 11 further includes:

[0307] The third current requirement is set based on the product of the first current requirement and the first weighted value; and

[0308] The fourth current requirement is set by multiplying the second current requirement by the second weighted value.

[0309] 20. The PFC method according to Scheme 11, wherein the filter is a low-pass filter.

[0310] 21. A power factor correction (PFC) system, comprising:

[0311] A desired turn-off period module that determines the desired turn-off period for the switch of the PFC circuit based on the input voltage to the PFC circuit and the output voltage of the PFC circuit; and

[0312] The switch control module, when the measured current through the inductor of the PFC circuit is greater than the required current through the inductor, switches the switch from the on state to the off state, and keeps the switch in the off state for the desired off period after switching from the on state to the off state.

[0313] 22. The PFC system according to claim 21, wherein the desired shutdown period module uses one of the following to set the desired shutdown period:

[0314] (i) An equation relating the input voltage and output voltage to the desired off-time period; and

[0315] (ii) A lookup table that associates the input voltage and output voltage with the desired off-time period.

[0316] 23. The PFC system according to Scheme 21, wherein the desired shutdown period module uses the following formula to set the desired shutdown period:

[0317]

[0318] Where DOP is the desired shutdown period, t p It is the scheduled switching cycle, v I It is the input voltage, and v o It is the output voltage.

[0319] 24. The PFC system according to Scheme 21, wherein the switch control module:

[0320] In response to determining that (i) the time interval between the transition from the ON state to the OFF state and (ii) the current time is greater than the desired OFF period, the switch is switched from the OFF state to the ON state; and

[0321] The switch remains on until the measured current through the inductor of the PFC circuit is greater than the required current through the inductor.

[0322] 25. The PFC system according to Scheme 24 further includes a current demand module that determines the demand current through the inductor based on the difference between the output voltage and the expected value of the output voltage.

[0323] 26. The PFC system according to Scheme 21, wherein the desired shutdown period module further determines the desired shutdown period based on the switching cycle of the switch.

[0324] 27. The PFC system according to claim 26 further includes a desired on-time module, which determines a desired on-time for the switch, wherein the desired on-time is variable.

[0325] The desired shutdown period module sets the desired shutdown period based on the switching cycle minus the desired connection period.

[0326] 28. The PFC system according to claim 26 further includes a desired on-time module, which sets the desired on-time for the switch based on the maximum current through the inductor, the required current through the inductor, and the input voltage.

[0327] The desired shutdown period module sets the desired shutdown period based on the switching cycle minus the desired connection period.

[0328] 29. The PFC system according to claim 26 further includes a desired on-time module, which sets a desired on-time for the switch based on the maximum current through the inductor, the required current through the inductor, the input voltage, and the output voltage.

[0329] The desired shutdown period module sets the desired shutdown period based on the switching cycle minus the desired connection period.

[0330] 30. The PFC system according to Scheme 26 further includes:

[0331] The discontinuous mode turn-on period module determines a first expected turn-on period for discontinuous mode operation based on the maximum current through the inductor, the required current through the inductor, and the input voltage;

[0332] A continuous mode turn-on period module determines a second expected turn-on period for continuous mode operation based on the maximum current through the inductor, the required current through the inductor, the input voltage, and the output voltage; and

[0333] The expected turn-on period module sets the third expected turn-on period for the switch to one of the first expected turn-on period and the second expected turn-on period.

[0334] The desired shutdown period module sets the desired shutdown period based on the switching cycle minus the third desired turn-on period.

[0335] 31. A power factor correction (PFC) method, comprising:

[0336] The desired off-time of the switch for the PFC circuit is determined based on the input voltage to the PFC circuit and the output voltage of the PFC circuit.

[0337] When the measured current through the inductor of the PFC circuit is greater than the required current through the inductor, the switch is switched from the ON state to the OFF state; and

[0338] After transitioning from the ON state to the OFF state, the switch remains in the OFF state for the desired OFF period.

[0339] 32. The PFC method according to Scheme 31, wherein determining the desired shutdown period includes: setting the desired shutdown period using one of the following:

[0340] (i) An equation relating the input voltage and output voltage to the desired off-time period; and

[0341] (ii) A lookup table that associates the input voltage and output voltage with the desired off-time period.

[0342] 33. The PFC method according to Scheme 31, wherein determining the desired shutdown period includes: setting the desired shutdown period using the following formula:

[0343]

[0344] Where DOP is the desired shutdown period, t p It is the scheduled switching cycle, v I It is the input voltage, and v o It is the output voltage.

[0345] 34. The PFC method according to Scheme 31 further includes:

[0346] In response to determining that (i) the time interval between the transition from the ON state to the OFF state and (ii) the current time is greater than the desired OFF period, the switch is transitioned from the OFF state to the ON state; and

[0347] The switch remains on until the measured current through the inductor of the PFC circuit is greater than the required current through the inductor.

[0348] 35. The PFC method according to claim 34 further includes: determining the required current through the inductor based on the difference between the output voltage and the expected value of the output voltage.

[0349] 36. The PFC method according to Scheme 31, wherein determining the desired shutdown period includes: further determining the desired shutdown period based on the switching cycle of the switch.

[0350] 37. The PFC method according to Scheme 36 further includes:

[0351] Determine the desired on-time period of the switch, wherein the desired on-time period is variable.

[0352] Determining the desired shutdown period includes setting the desired shutdown period based on the switching cycle minus the desired turn-on period.

[0353] 38. The PFC method according to claim 36, wherein determining the desired on-time includes: setting the desired on-time for the switch based on the maximum current through the inductor, the required current through the inductor, and the input voltage.

[0354] The desired shutdown period module sets the desired shutdown period based on the switching cycle minus the desired connection period.

[0355] 39. The PFC method according to claim 36 further includes: setting a desired on-time period for the switch based on the maximum current through the inductor, the required current through the inductor, the input voltage, and the output voltage.

[0356] Determining the desired shutdown period includes setting the desired shutdown period based on the switching cycle minus the desired turn-on period.

[0357] 40. The PFC method according to Scheme 36 further includes:

[0358] The first expected turn-on period for discontinuous mode operation is determined based on the maximum current through the inductor, the required current through the inductor, and the input voltage.

[0359] A second expected on-time period for continuous mode operation is determined based on the maximum current through the inductor, the required current through the inductor, the input voltage, and the output voltage; and

[0360] The third expected turn-on period of the switch is set to one of the first expected turn-on period and the second expected turn-on period.

[0361] Determining the desired shutdown period includes setting the desired shutdown period based on the switching cycle minus the third desired turn-on period.

[0362] 41. A power factor correction (PFC) system, comprising:

[0363] A PFC circuit receives an AC input voltage and uses a switch to generate a DC output voltage from the AC input voltage.

[0364] The first zero-crossing module determines the first zero-crossing point of the AC input voltage based on the following:

[0365] The first voltage and the first time when the AC input voltage changes from less than a first predetermined voltage to greater than the first predetermined voltage; and

[0366] The second voltage and the second time when the AC input voltage changes from less than the second predetermined voltage to greater than the second predetermined voltage.

[0367] Wherein, the first predetermined voltage is less than zero, and

[0368] Wherein, the second predetermined voltage is greater than zero;

[0369] A reference module that generates a sinusoidal reference signal corresponding at least in phase and frequency to the AC input voltage based on the first zero-crossing point; and

[0370] A switch control module controls the switching of the switch based on the sinusoidal reference signal.

[0371] 42. The PFC system according to Scheme 41 further includes:

[0372] The second zero-crossing module determines the second zero-crossing point of the sinusoidal reference signal based on the following:

[0373] The first value of the sinusoidal reference signal and the third time when the sinusoidal reference signal changes from greater than a third predetermined voltage to less than the third predetermined voltage; and

[0374] The second value of the sinusoidal reference signal and the fourth time when the sinusoidal reference signal changes from greater than the fourth predetermined voltage to less than the fourth predetermined voltage.

[0375] Wherein, the fourth predetermined voltage is less than zero, and

[0376] Wherein, the third predetermined voltage is greater than zero,

[0377] The reference module further generates the sinusoidal reference signal based on the second zero-crossing point.

[0378] 43. The PFC system according to Scheme 42, wherein the reference module generates the sinusoidal reference signal based on the difference between the first zero-crossing point of the AC input voltage and the second zero-crossing point of the sinusoidal reference signal.

[0379] 44. The PFC system according to claim 42, wherein the third predetermined voltage is equal to the second predetermined voltage, and

[0380] Wherein, the fourth predetermined voltage is equal to the first predetermined voltage.

[0381] 45. The PFC system according to Scheme 44, wherein the reference module further generates the sinusoidal reference signal based on half a period difference between the first zero-crossing point of the AC input voltage and the second zero-crossing point of the sinusoidal reference signal.

[0382] 46. ​​The PFC system according to Scheme 42, wherein:

[0383] The first predetermined voltage and the second predetermined voltage are equal in amplitude, and

[0384] The third predetermined voltage and the fourth predetermined voltage are equal in amplitude.

[0385] 47. The PFC system according to claim 41 further includes a filter module that filters the value of the AC input voltage measured using a voltage sensor and generates the first voltage and the second voltage based on the filtering.

[0386] 48. The PFC system according to claim 47 further includes:

[0387] The filter correction module determines the correction for the first zero-crossing point based on the frequency of the AC input voltage.

[0388] The reference module further generates the sinusoidal reference signal based on the correction.

[0389] 49. The PFC system according to Scheme 41, wherein the first zero-crossing module determines the first zero-crossing of the AC input voltage using linear interpolation based on the first voltage, the first time, the second voltage, and the second time.

[0390] 50. The PFC system according to Scheme 41 further includes: a current demand module for determining the current demand based on the sinusoidal reference signal.

[0391] When the current measured by the inductor of the PFC circuit is greater than the required current, the switch control module will change the switch from the on state to the off state.

[0392] 51. A power factor correction (PFC) method, comprising:

[0393] An AC input voltage is received via a PFC circuit, and a switch is used to generate a DC output voltage from the AC input voltage.

[0394] The first zero-crossing point of the AC input voltage is determined based on the following:

[0395] The first voltage and the first time when the AC input voltage changes from less than a first predetermined voltage to greater than the first predetermined voltage; and

[0396] The second voltage and the second time when the AC input voltage changes from less than the second predetermined voltage to greater than the second predetermined voltage.

[0397] Wherein, the first predetermined voltage is less than zero, and

[0398] The second predetermined voltage is greater than zero;

[0399] Based on the first zero-crossing point, a sinusoidal reference signal corresponding at least in phase and frequency to the AC input voltage is generated; and

[0400] The switching of the switch is controlled based on the sinusoidal reference signal.

[0401] 52. The PFC method according to Scheme 51 further includes:

[0402] The second zero-crossing point of the sinusoidal reference signal is determined based on the following:

[0403] The first value of the sinusoidal reference signal and the third time when the sinusoidal reference signal changes from greater than a third predetermined voltage to less than the third predetermined voltage; and

[0404] The second value of the sinusoidal reference signal and the fourth time when the sinusoidal reference signal changes from greater than the fourth predetermined voltage to less than the fourth predetermined voltage.

[0405] Wherein, the fourth predetermined voltage is less than zero, and

[0406] Wherein, the third predetermined voltage is greater than zero,

[0407] Generating the sinusoidal reference signal includes: further generating the sinusoidal reference signal based on the second zero-crossing point.

[0408] 53. The PFC method according to Scheme 52, wherein generating the sinusoidal reference signal includes: generating the sinusoidal reference signal based on the difference between the first zero-crossing point of the AC input voltage and the second zero-crossing point of the sinusoidal reference signal.

[0409] 54. The PFC method according to claim 52, wherein the third predetermined voltage is equal to the second predetermined voltage, and

[0410] Wherein, the fourth predetermined voltage is equal to the first predetermined voltage.

[0411] 55. The PFC method according to Scheme 54, wherein generating the sinusoidal reference signal further comprises: generating the sinusoidal reference signal based on half a period difference between the first zero-crossing point of the AC input voltage and the second zero-crossing point of the sinusoidal reference signal.

[0412] 56. The PFC method according to Scheme 52, wherein:

[0413] The first predetermined voltage and the second predetermined voltage are equal in amplitude, and

[0414] The third predetermined voltage and the fourth predetermined voltage are equal in amplitude.

[0415] 57. The PFC method according to Scheme 51 further includes:

[0416] The value of the AC input voltage measured using a voltage sensor is filtered; and

[0417] The first voltage and the second voltage are generated based on the filtering.

[0418] 58. The PFC method according to Scheme 57 further includes:

[0419] The correction for the first zero-crossing point is determined based on the frequency of the AC input voltage.

[0420] Generating the sinusoidal reference signal includes: further generating the sinusoidal reference signal based on the correction.

[0421] 59. The PFC method according to Scheme 51, wherein determining the first zero-crossing point includes: determining the first zero-crossing point of the AC input voltage using linear interpolation based on the first voltage, the first time, the second voltage, and the second time.

[0422] 60. The PFC method according to Scheme 51 further includes: determining the current demand based on the sinusoidal reference signal.

[0423] The switching of the switch includes: when the measured current through the inductor of the PFC circuit is greater than the required current, the switch is switched from the on state to the off state.

[0424] The foregoing description is illustrative in nature and is in no way intended to limit this disclosure, its application, or use. The broad teachings of this disclosure can be implemented in various forms. Therefore, while this disclosure includes specific examples, its true scope should not be limited thereto, as other modifications will become apparent upon examination of the drawings, specification, and the following claims. It should be understood that one or more steps of the method may be performed in a different order (or in parallel) without altering the principles of this disclosure. Furthermore, although each embodiment is described above as having specific features, any one or more of these features described relative to any embodiment of this disclosure may be implemented with any feature of other embodiments and / or combined with any feature of other embodiments, although such combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations and combinations of one or more embodiments remain within the scope of this disclosure.

[0425] Various terms, including “connection,” “combination,” “coupled,” “adjacent,” “next to,” “above,” “under,” and “arrangement,” are used to describe spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.). Unless explicitly described as “direct,” when describing a relationship between a first element and a second element in the above disclosure, the relationship can be a direct relationship where no other intermediate elements exist between the first and second elements, or an indirect relationship where one or more intermediate elements exist between the first and second elements (spatially or functionally). As used herein, the phrase at least one of A, B, and C should be understood to mean logic using a non-exclusive “OR” (A or B or C) and should not be understood to mean “at least one A, at least one B, and at least one C.”

[0426] In the accompanying drawings, as indicated by arrows, the direction of the arrows generally indicates the flow of information (e.g., data or instructions) that is meaningful to the illustration. For example, when components A and B exchange various kinds of information and information is transferred from component A to component B as illustrated, the arrow can point from component A to component B. This unidirectional arrow does not imply that no other information is being transferred from component B to component A. Furthermore, for information sent from component A to component B, component B may send a request for the information to component A or send a confirmation of receipt of the information to component A.

[0427] In this application, the terms "module" or "controller" may be replaced by the term "circuit" as defined below. The term "module" may refer to, or may include, a subset of, the following: application-specific integrated circuits (ASICs); digital, analog, or mixed-signal analog / digital discrete circuits; digital, analog, or mixed-signal analog / digital integrated circuits; combinational logic circuits; field-programmable gate arrays (FPGAs); processor circuitry (shared, dedicated, or grouped) that executes code; memory circuitry (shared, dedicated, or grouped) that stores code executed by the processor circuitry; other suitable hardware components that provide the described functionality; or combinations of some or all of the above components, for example, in a system-on-a-chip.

[0428] A module includes one or more interface circuits. In some examples, the interface circuits may include wired or wireless interfaces connected to a local area network (LAN), the Internet, a wide area network (WAN), or a combination thereof. The functionality of any given module in this disclosure can be distributed across multiple modules connected via the interface circuits. For example, multiple modules can allow for load balancing. In yet another example, a server (also known as a remote or cloud) module may perform certain functions on behalf of a client module.

[0429] Some or all of the characteristics of a module can be defined using languages ​​used for hardware description, such as IEEE Standard 1364-2005 (commonly known as "Verilog") and IEEE Standard 1076-2008 (commonly known as "VHDL"). Hardware description languages ​​can be used to fabricate and / or program hardware circuits. In some implementations, some or all of the characteristics of a module can be defined using a language that includes code and hardware description as described below, such as IEEE 1666-2005 (commonly known as "System C").

[0430] The terms "code" used above can include software, firmware, and / or microcode, and can refer to programs, routines, functions, classes, data structures, and / or objects. The term "shared processor circuit" includes a single processor circuit that executes some or all of the code from multiple modules. The term "group processor circuit" includes a processor circuit combined with additional processor circuitry that executes some or all of the code from one or more modules. References to multiple processor circuits include multiple processor circuits on a discrete die, multiple processor circuits on a single die, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or a combination thereof. The term "shared memory circuit" includes a single memory circuit that stores some or all of the code from multiple modules. The term "group memory circuit" includes a memory circuit combined with additional memory that stores some or all of the code from one or more modules.

[0431] The term memory circuit is a subset of the term computer-readable medium. As used herein, the term computer-readable medium does not include transient electrical or electromagnetic signals propagating through a medium (e.g., on a carrier wave); therefore, the term computer-readable medium can be considered tangible and non-transitory. Non-limiting examples of non-transitory computer-readable media are non-volatile memory circuits (e.g., flash memory circuits, erasable programmable read-only memory circuits, or mask read-only memory circuits), volatile memory circuits (e.g., static random access memory circuits or dynamic random access memory circuits), magnetic storage media (e.g., analog or digital magnetic tape or hard disk drives), and optical storage media (e.g., CDs, DVDs, or Blu-ray discs).

[0432] The apparatus and methods described in this application can be implemented, in part or in whole, by a dedicated computer created by configuring a general-purpose computer to execute one or more specific functions contained in a computer program. The aforementioned function blocks and flowchart elements serve as software specifications that can be translated into computer programs through the routine work of skilled technicians or programmers.

[0433] A computer program includes processor-executable instructions stored on at least one non-transitory computer-readable medium. A computer program may also include or depend on stored data. A computer program may include a basic input / output system (BIOS) for interacting with the hardware of a special-purpose computer, device drivers for interacting with specific devices of the special-purpose computer, one or more operating systems, user applications, background services, background applications, etc.

[0434] Computer programs may include: (i) descriptive text to be parsed, such as HTML (Hypertext Markup Language), XML (Extensible Markup Language), or JSON (JavaScript Object Notation); (ii) assembly code; (iii) object code generated from source code by a compiler; (iv) source code executed by an interpreter; and (v) source code compiled and executed by a just-in-time (JIT) compiler, etc. As an example only, source code may be written using language syntax, including languages ​​such as C, C++, C#, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, etc. Fortran, Perl, Pascal, Curl, OCaml, HTML5 (Hypertext Markup Language 5th Edition), Ada, ASP (Dynamic Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Lua, MATLAB, SIMULINK and

[0435] Unless an element is explicitly listed using the phrase “for a method of…” or in the case of a method claim using the phrase “for an operation of…” or “for a step of…”, the element listed in the claim is not intended to be a functionally defined element in the sense of 35 U.SC § 112(f).

Claims

1. A power factor correction (PFC) system, comprising: A desired shutdown period module determines a desired shutdown period for a switch in the PFC circuit based on the input voltage to the PFC circuit and the output voltage of the PFC circuit, wherein the desired shutdown period module uses one of the following to set the desired shutdown period: (i) an equation relating the input voltage and the output voltage to the desired shutdown period, and (ii) a lookup table relating the input voltage and the output voltage to the desired shutdown period; The switch control module, when the measured current through the inductor of the PFC circuit is greater than the required current through the inductor, switches the switch from the on state to the off state, and keeps the switch in the off state for the desired off period after switching from the on state to the off state. A voltage control module configured to set the initial current demand through the inductor based on the difference between the desired output voltage of the PFC circuit and the output voltage of the PFC circuit; and A current demand module is configured to set the required current through the inductor based on the initial current demand and a sinusoidal reference signal.

2. The PFC system according to claim 1, wherein, The desired shutdown period module uses the following formula to set the desired shutdown period: Where DOP is the desired shutdown period, t p It is the scheduled switching cycle, v I It is the input voltage, and v o It is the output voltage.

3. The PFC system according to claim 1, wherein, The switch control module: In response to determining that (i) the time between the transition from the ON state to the OFF state and (ii) the current time is greater than the desired OFF period, the switch is switched from the OFF state to the ON state; as well as The switch remains on until the measured current through the inductor of the PFC circuit is greater than the required current through the inductor.

4. The PFC system according to claim 3 further includes a current demand module, which determines the required current through the inductor based on the difference between the output voltage and the expected value of the output voltage.

5. The PFC system according to claim 1, wherein, The desired shutdown period module also determines the desired shutdown period based on the switching cycle of the switch.

6. The PFC system according to claim 5 further includes a desired on-time module, the desired on-time module determining a desired on-time period for the switch, wherein, The desired connection period is variable. The desired shutdown period module sets the desired shutdown period based on the switching cycle minus the desired connection period.

7. The PFC system of claim 5 further includes a desired on-time module, the desired on-time module setting a desired on-time for the switch based on the maximum current through the inductor, the required current through the inductor, and the input voltage. in, The desired shutdown period module sets the desired shutdown period based on the switching cycle minus the desired turn-on period.

8. The PFC system of claim 5 further includes a desired on-time module, the desired on-time module setting a desired on-time for the switch based on the maximum current through the inductor, the required current through the inductor, the input voltage, and the output voltage. in, The desired shutdown period module sets the desired shutdown period based on the switching cycle minus the desired turn-on period.

9. The PFC system according to claim 5, further comprising: The discontinuous mode turn-on period module determines a first expected turn-on period for discontinuous mode operation based on the maximum current through the inductor, the required current through the inductor, and the input voltage; A continuous mode turn-on period module determines a second expected turn-on period for continuous mode operation based on the maximum current through the inductor, the required current through the inductor, the input voltage, and the output voltage; and The expected turn-on period module sets the third expected turn-on period for the switch to one of the first expected turn-on period and the second expected turn-on period. The desired shutdown period module sets the desired shutdown period based on the switching cycle minus the third desired turn-on period.

10. The PFC system according to claim 1, wherein, The current demand module includes a notch filter module, which is configured to apply a notch filter to the initial current demand. The current demand module is configured to set the demand current based on the initial current demand after the notch filter is applied.

11. The PFC system according to claim 10, wherein, The notch filter is one of a first-order polynomial notch filter and a second-order polynomial notch filter.

12. The PFC system according to claim 11, wherein, The notch filter is represented by a second-order transfer function: ， Where b0, b1, b2, a0, a1, and a2 are filter coefficients, and z is the initial current requirement input to the notch filter.

13. The PFC system of claim 12 further includes a filter coefficient module configured to determine one or more filter coefficients based on the frequency of the input AC voltage.

14. The PFC system according to claim 13, wherein, The notch filter has a notch frequency that is twice the frequency of the input AC voltage.

15. The PFC system according to claim 14, wherein, The filter coefficient module is configured to determine the one or more filter coefficients using one or more lookup tables and / or functions that associate frequencies with the one or more filter coefficients.

16. The PFC system according to claim 11, further comprising: A first saturation module is configured to apply one or more restrictions to the initial current demand before outputting the initial current demand to the notch filter module; The second saturation module is configured to apply one or more restrictions to the initial current demand output by the notch filter module; The multiplication module is configured to generate an output by multiplying the initial current demand output by the second saturation module with a reference signal corresponding to the input AC voltage. as well as An absolute value module is configured to set the required current to the absolute value of the output of the multiplication module.

17. A power factor correction (PFC) method, comprising: The desired off-time for the switch of the PFC circuit is determined based on the input voltage to the PFC circuit and the output voltage of the PFC circuit, wherein determining the desired off-time includes setting the desired off-time using one of the following: (i) an equation relating the input voltage and the output voltage to the desired off-time, and (ii) a lookup table relating the input voltage and the output voltage to the desired off-time. When the measured current through the inductor of the PFC circuit is greater than the required current through the inductor, the switch is changed from the on state to the off state. After transitioning from the ON state to the OFF state, the switch remains in the OFF state for the desired OFF period. The initial current requirement through the inductor is set based on the difference between the desired output voltage of the PFC circuit and the output voltage of the PFC circuit; and The required current through the inductor is set based on the initial current requirement and a function of the sinusoidal reference signal.

18. The PFC method according to claim 17, wherein, Determining the desired shutdown period includes setting the desired shutdown period using the following formula: Where DOP is the desired shutdown period, t p It is the scheduled switching cycle, v I It is the input voltage, and v o It is the output voltage.

19. The PFC method according to claim 17, further comprising: In response to determining that (i) the time between the transition from the ON state to the OFF state and (ii) the current time is greater than the desired OFF period, the switch is transitioned from the OFF state to the ON state; as well as The switch remains on until the measured current through the inductor of the PFC circuit is greater than the required current through the inductor.

20. The PFC method according to claim 19, further comprising: The required current through the inductor is determined based on the difference between the output voltage and the expected value of the output voltage.

21. The PFC method according to claim 17, wherein, Determining the desired shutdown period includes: further determining the desired shutdown period based on the switching cycle of the switch.

22. The PFC method according to claim 21, further comprising: Determine the desired on-time period for the switch, wherein the desired on-time period is variable. Determining the desired shutdown period includes setting the desired shutdown period based on the switching cycle minus the desired turn-on period.

23. The PFC method according to claim 22, wherein, Determining the desired on-time period includes setting the desired on-time period for the switch based on the maximum current through the inductor, the required current through the inductor, and the input voltage. Determining the desired shutdown period includes setting the desired shutdown period based on the switching cycle minus the desired turn-on period.

24. The PFC method according to claim 21, further comprising: The desired on-time for the switch is set based on the maximum current through the inductor, the required current through the inductor, the input voltage, and the output voltage. Determining the desired shutdown period includes setting the desired shutdown period based on the switching cycle minus the desired turn-on period.

25. The PFC method according to claim 21, further comprising: The first expected turn-on period for discontinuous mode operation is determined based on the maximum current through the inductor, the required current through the inductor, and the input voltage. The second expected turn-on period for continuous mode operation is determined based on the maximum current through the inductor, the required current through the inductor, the input voltage, and the output voltage. as well as The third expected turn-on period for the switch is set to one of the first expected turn-on period and the second expected turn-on period. Determining the desired shutdown period includes setting the desired shutdown period based on the switching cycle minus the third desired turn-on period.

26. The PFC method according to claim 17, further comprising: Apply a notch filter to the initial current requirement. Setting the required current includes setting the required current based on the initial current requirement after applying the notch filter.

27. The PFC method according to claim 26, wherein, The notch filter is one of a first-order polynomial notch filter and a second-order polynomial notch filter.

28. The PFC method according to claim 26, wherein, The notch filter is represented by a second-order transfer function: ， Where b0, b1, b2, a0, a1, and a2 are filter coefficients, and z is the initial current requirement input to the notch filter.

29. The PFC method according to claim 28, further comprising: One or more filter coefficients are determined based on the frequency of the input AC voltage.

30. The PFC method according to claim 29, wherein, The notch filter has a notch frequency that is twice the frequency of the input AC voltage.

31. The PFC method according to claim 29, wherein, Determining the one or more filter coefficients includes using one or more lookup tables and / or functions that associate frequencies with the one or more filter coefficients.

32. The PFC method according to claim 26, further comprising: One or more first constraints are applied to the initial current requirement before the notch filter is applied. After applying the notch filter, one or more second constraints are applied to the initial current requirement; The output is generated by multiplying the initial current demand after applying one or more of the second constraints with a reference signal corresponding to the input AC voltage. as well as Set the required current to the absolute value of the output.

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