Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M1/00—Details of apparatus for conversion
  • H02M1/0048—Circuits or arrangements for reducing losses
  • H02M1/0054—Transistor switching losses
  • H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M3/00—Conversion of dc power input into dc power output
  • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
  • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
  • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
  • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
  • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
  • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/30—Driver circuits
  • H05B45/36—Circuits for reducing or suppressing harmonics, ripples or electromagnetic interferences [EMI]
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/30—Driver circuits
  • H05B45/37—Converter circuits
  • H05B45/3725—Switched mode power supply [SMPS]
  • H05B45/375—Switched mode power supply [SMPS] using buck topology
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/30—Driver circuits
  • H05B45/37—Converter circuits
  • H05B45/3725—Switched mode power supply [SMPS]
  • H05B45/38—Switched mode power supply [SMPS] using boost topology
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
  • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
  • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Definitions

• Embodiments of the present disclosure generally relate to the field of antenna design, and more particularly, to a control method and apparatus of buck converting circuit, buck converting circuit, LED driver and LED device.
• LED light emitting diode
• a LED driver is commonly used to provide constant drive current for LEDs.
• LED driver usually uses combination of flyback or boost power factor correction (PFC) circuit followed by buck converting circuit using Digital BUCK solution by T off control, wherein T off is the off time of a switch in the LED driver.
• PFC boost power factor correction
• FIG. 1 shows a diagram which shows an overall structure of LED driver; as shown in figure 1, the LED driver 50 includes electromagnetic Interference (EMI) filter 51, boost PFC circuit 52, direct current (DC) -DC converting circuit 53 (such as buck converting circuit) .
• the EMI filter 51 filters the Electromagnetic Interference;
• the boost PFC circuit 52 converts the input AC power into DC power;
• a buck converting circuit 53 converts the DC voltage of the boost PFC circuit 52 into an output voltage, the output voltage is used to drive a lighting device, for example, the lighting device is LED.
• the detail function of other part may refer to relevant art which is omitted here, for example, a controller 54 controls the DC-DC converting circuit 53; and a control circuit 55 communicates with the controller 54.
• the control circuit 54 communicate with a peripheral device via an interface.
• the peripheral devices may be dimmers, sensors, controllers, security device, etc.
• FIG. 2 shows the relationship between output current and Safety or Separated Extra Low Voltage (SELV) output voltage of a LED driver.
• the LED driver shall provide wide output current range from 100mA to 1050mA.
• a buck converting circuit operates in continuous current mode (CCM) if a current I_L through an inductor never falls to zero and operates in discontinuous current mode (DCM) if a current I_L through an inductor will falls to zero during a period.
• CCM continuous current mode
• DCM discontinuous current mode
• FIG. 3 shows a block diagram which shows a solution of the buck converting circuit.
• Figure 4 shows a diagram of the existed buck converting circuit.
• MCU microcontroller unit
• PID Proportional Integral Derivative
• embodiments of the present disclosure provide a control method and apparatus of buck converting circuit, buck converting circuit, LED driver and LED device. It is expected to improve the load regulation.
• a buck converting circuit control method applied in a buck converting circuit is provided, the method including:
• the resonant time is calculated according to a resonant frequency.
• step of determining a compensation time according to the resonant time including:
• determining a sign of the compensation time is positive or negative according to the resonant time
• step of determining the sign of the compensation time including:
• the total Toff time is equal to a target T off time plus the compensation time.
• DCM Discontinuous Conduction Mode
• the drive control signal is PWM signal.
• a control apparatus applied in a buck converting circuit, the apparatus including:
• a calculating unit configured to calculate a resonant time
• a determining unit configured to determine a compensation time according to the resonant time
• an updating unit configured to update a total T off time of a switch in the buck converting circuit according to the compensation time.
• a buck converting circuit including:
• control unit configured to receive an input voltage and generate a drive control signal of the switch circuit by using the updated T off time
• a buck circuit connected to the switch circuit and configured to output the voltage.
• control apparatus is connected to the buck circuit to obtain the feedback output voltage.
• the input voltage is DC voltage.
• a LED driver used to drive an LED load
• the LED driver including:
• the Buck converting circuit configured to provide a substantially constant current for powering the LED load.
• a light emitting diode (LED) device including:
• At least one LED illumination source At least one LED illumination source
• a LED driver as mentioned in the fourth aspect, configured to electrically couple to at least one LED illumination source for driving the LED illumination source.
• making a correction to the T off time of a switch based on resonant time of the current and output voltage so as to get more accurate output current and to improve the load regulation.
• Fig. 1 is a diagram which shows an overall structure of LED driver
• Fig. 2 is a diagram which shows relationship between output current and voltage
• Fig. 3 is a block diagram which shows a solution of a buck converting circuit
• Fig. 4 is a diagram which show a structure of the existed buck converting circuit
• Fig. 5 is a schematic circuit diagram which show a structure of the existed buck converting circuit
• Fig. 6 is a diagram which shows the ideal and actual iLED current in DCM; .
• Fig. 7 and 8 are diagrams which show DCM output current
• Fig. 9 is a diagram which shows a current resonance in accordance with an embodiment of the present disclosure.
• Fig. 10 is a diagram which shows a relationship in accordance with an embodiment of the present disclosure.
• Fig. 11 is a diagram which shows a buck converting circuit in accordance with an embodiment of the present disclosure
• Fig. 12 is a diagram which shows an example of the control solution in accordance with an embodiment of the present disclosure.
• Fig. 13 is a flowchart which shows an example of the control method in accordance with an embodiment of the present disclosure
• Fig. 14 is a diagram which shows an example of the control method in accordance with an embodiment of the present disclosure.
• Fig. 15 is a diagram which shows a structure of the control apparatus in accordance with an embodiment of the present disclosure.
• Fig. 16 is a schematic circuit diagram which show a structure of the buck converting circuit in accordance with an embodiment of the present disclosure.
• the terms “first” and “second” refer to different elements.
• the singular forms “a” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise.
• the term “based on” is to be read as “based at least in part on” .
• the term “cover” is to be read as “at least in part cover” .
• the term “one embodiment” and “an embodiment” are to be read as “at least one embodiment” .
• the term “another embodiment” is to be read as “at least one other embodiment” .
• Other definitions, explicit and implicit, may be included below.
• FIG. 5 is a schematic circuit diagram which show a structure of the existed buck converting circuit.
• the buck converting circuit includes MCU, totem pole circuit (taken as Mos drive circuit) , current peak limiter circuit and buck circuit.
• Vin represents DC input voltage detection.
• Vout represents LED output voltage detection. Isns is not applied yet.
• PWM is taken as Mos Gate (switch) driver. Break means PWM breaker trigger. Ref represents current limit reference. Other part may refer to relevant art which is omitted here.
• Figure 6 shows the ideal and actual output current iLED current in DCM, as shown in Figure 6, the ideally value of an inductor current I_L is 0, ideally wherein T period is a period of the inductor current in DCM charge and discharge to 0 until next start point which align one cycle of PWM signal.
• Ipk means peak of the inductor current. That is, when the inductor current I_L falls to zero, there exists no circuit oscillation in theory. But as shown in figure 5, as there exists parasite capacitor around which will form an oscillating circuit, a sinusoidal current signal will appear and disappear after a few cycles as shown in figure 6 case 1 and case 2.
• next switching start point is negative, switch is turned to on state when actual I_L ⁇ 0 (Next switching start point B') , iLED1 ⁇ ideally iLED, T period1 >T period ;
• next switching start point is positive, switch is turned to on state when actual>0 (Next switching start point B”) , iLED2>ideally iLED, T period2 ⁇ T period ; so T off_actual_1 in case 1 and T off_actual_2 in case 2 are not equal to T off_target .
• Figure 7 and 8 are diagrams which show DCM output current in 100mA and 200mA. As shown in Figure 7 and 8, as mentioned above, when the buck converting circuit works in the DCM mode and chooses low current output, load regulation will be out of range.
• the frequency of the resonant various with output voltage. Next switching start point could be positive or negative depends on LED load.
• a work mode of the buck converting circuit is Discontinuous Conduction Mode, DCM, making a correction to the T off time of a switch based on resonant time of the current and output voltage, so as to get more accurate output current and to improve the load regulation.
• FIG. 14 shows a diagram of the control method, as shown in Fig. 14, the method includes:
• a compensation time is determined according to the resonant time
• a total T off time of a switch in the buck converting circuit is updated according to the compensation time
• a drive control signal of the switch is generated by using the updated T off time so as to obtain an output voltage.
• this method introduces a compensation time T off_comp to shift the actual T off time (such as T off_actual_1 and T off_actual_2 in case 1 and case 2 of Figure 6) .
• FIG. 9 further shows the current resonance generated due to the parasite capacitor.
• T off_dcm is the resonant time belongs to the T off .
• T_resonant related to parameters of components such as Diode parasite capacitor, and inductor.
• T resonant is equal to reciprocal of resonant frequency, which means on period (cycle) of resonant time of LC circuit (as shown in figure 6, capacitor C and inductor L) and leads to the voltage swinging when the switch is being switched off, it is a constant value.
• resonant frequency Lr means Inductance (inductor value, actual tolerance is +/-1%, stored inside the MCU FLASH memory)
• Cr means Diode parasite Capacitance
• a resonant time T off_dcm is the resonant time belongs to a target T off time started from the start point of the resonant time of LC circuit (or the time point when the inductor current I_L falls to zero) and is ended to the next switching start point, as shown in figure 6,
• the target T off time T off_target is the off time of the switch (time of low level of the PWM signal) when I_L is equal to ideally value 0, which is started from point A (located at maximum I_L) to the Next switching start point B (start point of the next high level of the PWM signal, that is, start point of next T on which is on time of the switch) wherein T off_target can be obtained by looking up table in DCM.
• T off_dcm could be less or larger than T resonant , for examples, it determined by T off_target could be calculated.
• T off_dcm is equal to the T off_target minus the time for the inductor current to fall from the maximum value to 0, that is,
• T off_dcm is the intended time that the switch should be switched off in order to control the amount of power transferred.
• the timing of this off-time is adjusted in order to achieve zero voltage switching (or be close to zero voltage switching) in knowledge of the time period /inverted resonant frequency of the resonance of the circuit.
• a compensation time T off_comp is determined according to the resonant time T off_dcm ;
• T off_comp could be positive value or negative value, depends on the resonant time T off_dcm . Using phase shift to compensate theT off_actual_1 in case 1 and T off_actual_2 in case2. That is, To calculate Resonant time, Add parameter “T off_comp ” for compensation the total T off time, in order to get more accurate output current.
• step of S2 including:
• a sign of the compensation time is determined as positive or negative according to the resonant time
• S21 determines the sign of the compensation time according to a relationship of a next switching start point and a phase range of a inductor current generated during the resonant time;
• the sign of the compensation time when a next target switching start point of is located in a first phase range of a inductor current generated during the resonant time, the sign of the compensation time is negative; when a next switching start point of is located in a second phase range of a inductor current generated during the resonant time, the sign of the compensation time is positive.
• Figure 10 shows the relationship of a next switching start point and a phase range of a inductor current generated during the resonant time .
• first phase range that is, a next target switching start point of is located in a phase 1 or phase 2
• second phase range that is, a next target switching start point of is located in a phase 3 or phase 4
• the sign of the compensation time T off_comp can be determined as positive.
• the range of phase 1 is 180° ⁇ 270°
• the range of phase 2 is 270° ⁇ 360°
• the range of phase 3 is 0° ⁇ 90°
• the range of phase 4 is 90° ⁇ 180°.
• value of the compensation time is determined according the value of resonant time T off_dcm.
• the formula of the compensation time is formula A
• the formula of the compensation time is formula B
• the formula of the compensation time is formula C
• the formula of the compensation time is formula D.
• a next target switching start point of is located in phase 1 of a inductor current generated during the resonant time
• when a next target switching start point of is located in phase 2 of a inductor current generated during the resonant time when a next target switching start point of is located in phase 3 of a inductor current generated during the resonant time
• when a next target switching start point of is located in phase 4 of a inductor current generated during the resonant time when a next target switching start point of is located in phase 1 of
• a total T off time of a switch in the buck converting circuit is updated according to the compensation time; for example, the total T off time is equal to a target T off time plus the compensation time.
• T off_actual T off_target +T off_comp
• T off_target can be obtained by looking up table in DCM
• L represents the value of the Inductor (inductance)
• ⁇ Ipk is the peak of the current
• iLED LED output current
• Vout represents LED output voltage
• step S1-S3 can be performed.
• the drive control signal is PWM signal.
• Figure 11 shows a diagram of the buck converting circuit of the present invention. It is different from Figure 5, the circuit further includes Low frequency op-amp circuit which is used for compensation the total T off time, and Isns represents the Rshunt mean voltage detection. In DCM, 0 ⁇ the current of Rshunt ⁇ iLED; T off_target ⁇ T period (see formulas) .
• Figure 13 shows a flowchart of the control method, as shown in Fig. 13, the method includes:
• the mean of current I is checked according to the input voltage and output voltage
• the work mode of the buck converting circuit is CCM or DCM is determined according to the mean of current I; when the work mode is DCM, performing 1303-1306, when the work mode is CCM, performing 1307;
• the buck converting circuit operates in continuous current mode (CCM) if a current I through an inductor never falls to zero and operates in discontinuous current mode (DCM) if a current I through an inductor will falls to zero during a period.
• CCM continuous current mode
• DCM discontinuous current mode
• T off_target is obtained in DCM
• T resonant and T off_dcm are calculated
• a compensation time T off_comp is determined according to the resonant time (T resonant and T off_dcm ) ;
• a total T off_actual of a switch is updated according to the T off_comp ;
• T off is obtained in CCM based on the relevant art which is omitted here.
• the implement of 1304-1306 may refer to S1-S3 which is omitted here.
• a drive control signal of the switch is generated by using the updated T off time so as to obtain an output voltage.
• Low frequency op-amp circuit is used to check the value.
• MCU is used to calculate and generate the value or signal.
• T off and T on correspond to the time of low level and high level of the PWM signal respectively.
• the drive control signal PWM signal
• PID proportional integral derivative
• duty cycle of the PWM can be adjusted by the PID loop based on the relevant art which is omitted here, the PWM signal is taken as the signal to drive the Mos drive circuit (taken as the switch) .
• this method can be flexible usage in different products; and support CCM/DCM performance –wider operation window for output power.
• the method selects a correction for the end of the off-time in DCM in order to achieve valley switching (switching at or close to the zero crossings) .
• FIG. 15 is a diagram which shows a structure of the control apparatus in accordance with an embodiment of the present disclosure, As shown in figure 15, the apparatus 1500 including:
• a calculating unit 1501 configured to calculate a resonant time
• a determining unit 1502 configured to determine a compensation time according to the resonant time
• an updating unit 1503 configured to update a total T off time of a switch in the buck converting circuit according to the compensation time.
• the implement of the calculating unit 1501, determining unit 1502, updating unit 1503 may refer to S1-S3 mentioned in the first aspect of embodiment which is omitted here.
• the resonant time is the resonant time belongs to a target T off time.
• the determining unit 1502 determines a sign of the compensation time is positive or negative according to the resonant time and determines a value of the compensation time.
• the determining unit 1502 determines the sign of the compensation time according to a relationship of a next switching start point and a phase range of a inductor current generated during the resonant time;
• the sign of the compensation time when a next target switching start point of is located in a first phase range of a inductor current generated during the resonant time, the sign of the compensation time is negative; when a next switching start point of is located in a second phase range of a inductor current generated during the resonant time, the sign of the compensation time is positive.
• the total T off time is equal to a target T off time plus the compensation time.
• DCM Discontinuous Conduction Mode
• calculating unit 1501, determining unit 1502, updating unit 1503 perform the corresponding behavior.
• the drive control signal is PWM signal.
• control apparatus 1500 may be integrated into the MCU.
• control apparatus 1500 and the MCU may be configured separately.
• control apparatus 1500 may be configured as a chip connected to the MCU, with the functions of the control apparatus 1500.
• a buck converting circuit is provided, the buck converting circuit (refer to figure 12) including:
• control unit 1603 configured to receive an input voltage and generate a drive control signal of the switch circuit by using the updated T off time
• a buck circuit 1604 connected to the switch circuit and configured to output the voltage.
• the control apparatus 1601 is illustrated in the second aspect of embodiments, and the same contents as those in the second aspect of embodiments are omitted.
• control apparatus 1601 is connected to the buck circuit 1604 to obtain the feedback output voltage.
• the input voltage is DC voltage
• the output voltage is DC voltage
• the buck converting circuit can be taken as DC-DC converting circuit.
• FIG. 12 shows a diagram of the control solution, as shown in Fig. 12, different from figure 3, the control apparatus obtains the feedback output voltage and determines the work mode is CCM or DCM based on the method mentioned in 1302, when the work mode is DCM, control apparatus updates a total T off time of a switch in the buck converting circuit according to the compensation time.
• MCU (corresponding to control unit 1603) generates the PWM signal by using PID according to the updated total T off time and DC input.
• the PWM signal is taken as the signal to drive the Mos drive circuit (corresponding to a switch circuit 1602) .
• the Mos drive circuit (corresponding to a switch circuit 1602) can be taken as the switch in the buck converting circuit.
• the buck circuit (corresponding to a buck circuit 1604) connected to the Mos drive circuit (corresponding to a switch circuit 1602) and configured to output the voltage.
• the detail function of other part may refer to relevant art which is omitted here.
• the LED driver includes:
• the Buck converting circuit configured to provide a substantially constant current for powering the LED load.
• the buck converting circuit is illustrated in the third aspect of embodiments, and the same contents as those in the third aspect of embodiments are omitted.
• the LED driver is electrically couple to at least one LED illumination source for driving the LED illumination source.
• rectifier circuit includes an EMI filter 51 and a boost PFC circuit 52, the EMI filter 51 filters the Electromagnetic Interference; the boost PFC circuit 52, converts the input AC power into DC power; a Buck converting circuit 53, configured to convert the DC voltage of the boost PFC circuit 52 into an output voltage, the output voltage is used to drive a lighting device, for example, the lighting device is LED.
• the LED driver configured to supply direct current (DC) power to the lighting device
• the lighting device may be an LED device.
• a LED device is provided in the embodiments.
• the LED device includes: at least one LED illumination source and a LED driver configured to electrically couple to at least one LED illumination source for driving the LED illumination source.
• the LED driver is illustrated in the fourth aspect of embodiments, and the same contents as those in the fourth aspect of embodiments are omitted.
• various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device.

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• 2021
  • 2021-08-10 EP EP21947824.5A patent/EP4338553A1/en active Pending
  • 2021-08-10 WO PCT/CN2021/111836 patent/WO2023272886A1/en active Application Filing
  • 2021-08-10 CN CN202180100037.XA patent/CN117598029A/zh active Pending

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