boost converter

Abstract

A boost converter includes an inductor and a diode electrically connected in series between an input voltage and an output voltage; a transistor electrically coupled to the interconnect node of the inductor and the diode; and a controller that controls the switching of the transistor based on a transient mode and an estimated load current. Before leaving a light-to-heavy load transient mode, the output voltage has at least one first valley point, the value of which is a transient voltage criticality; and then has at least one second valley point, the value of which is higher than the first valley point.

Description

Technical Field

[0001] This invention relates to a boost converter, and more particularly to a boost converter with a fast transient response. Background Technology

[0002] A boost converter is a type of DC-to-DC power converter used to increase the input voltage to the output voltage. Boost converters are a type of switched-mode power supply.

[0003] Boost converters can be used as drivers for backlight panels, such as mini-LED backlight panels. Because mini-LED backlight panels experience rapid transient changes, boost converters with fast transient responses are required.

[0004] Peretz et al. proposed a boost converter with fast transient response, disclosed in "Hardware-Efficient Programmable-Deviation Controller for Indirect Energy Transfer DC–DC Converters," IEEE Transactions on Power Electronics, Vol. 30, No. 6, pp. 3376–3388, June 2015, the contents of which are considered part of this specification. However, Peretz's boost converter uses a lookup table to store fixed coefficients to control load transients, thus generating oscillations to mitigate load transients.

[0005] Therefore, there is an urgent need to propose a novel mechanism to effectively control the load transients of the boost converter. Summary of the Invention

[0006] In view of the above, one of the objectives of this invention is to provide a boost converter with fast transient response, which can avoid harmful oscillations and effectively accelerate light to heavy load transients.

[0007] According to an embodiment of the present invention, a boost converter includes an inductor, a diode, a transistor, and a controller. The inductor and diode are electrically connected in series between the input voltage and the output voltage. The transistor is electrically coupled to the interconnect node of the inductor and diode. The controller controls the switching of the transistor based on a transient mode and an estimated load current. Before leaving the light-to-heavy load transient mode, the output voltage has at least one first valley point, the value of which is a transient voltage critical point; subsequently, it has at least one second valley point, the value of which is higher than the first valley point.

[0008] Preferably, it further includes: a capacitor electrically connected between the output voltage and ground.

[0009] Preferably, it further includes: a transient detector that detects the transient mode by comparing the output voltage with a steady-state window, wherein the steady-state window is located between an upper boundary and a lower boundary.

[0010] Preferably, it further includes a current estimator that generates the estimated load current based on the change in the output voltage.

[0011] Preferably, the estimated load current is generated based on the slope of the output voltage during the initial period of the light to heavy load transient mode.

[0012] Preferably, when the inductor current is greater than the estimated load current, the output voltage after a preset time is recorded as the transient voltage critical.

[0013] Preferably, the controller performs the following steps in the light to heavy load transient mode: (a) when the light to heavy load transient mode is detected, turning on the transistor; (b) when the inductor current is greater than the estimated load current and the output voltage is lower than the transient voltage threshold, turning off the transistor; and (c) when the inductor current is lower than the estimated load current and the output voltage is higher than the lower boundary, leaving the light to heavy load transient mode, otherwise returning to step (b).

[0014] Preferably, the steady-state window has an extended lower boundary that is lower than the lower boundary, with a preset difference between the two; if the output voltage is lower than the lower boundary but higher than the extended lower boundary, the transient voltage threshold is replaced by an adaptive transient voltage threshold, wherein the adaptive transient voltage threshold is higher than the transient voltage threshold, with a preset difference between the two.

[0015] Preferably, the value of the second valley point is the critical value of the adaptive transient voltage.

[0016] Preferably, an adaptive load current is provided that is higher than the estimated load current, with a preset difference between the two; if the inductor current is higher than the adaptive load current, the controller shuts off the transistor.

[0017] Preferably, the adaptive load current is obtained based on the lower boundary and the transient voltage threshold.

[0018] Preferably, the difference between the second valley point and the transient voltage threshold is less than the height of the steady-state window.

[0019] By means of the above technical solution, the present invention has at least the following advantages: the boost converter of the present invention can avoid harmful oscillations and can effectively accelerate light to heavy load transients. Attached Figure Description

[0020] Figure 1 A block diagram showing a boost converter with fast transient response according to an embodiment of the present invention.

[0021] Figure 2A A flowchart illustrating the light to heavy load transient mode of the boost converter according to an embodiment of the present invention is shown.

[0022] Figure 2B The waveform diagrams of relevant signals in the transient mode of light to heavy load are shown.

[0023] Figure 3A A flowchart illustrating the heavy-to-light load transient mode of the boost converter according to an embodiment of the present invention is shown.

[0024] Figure 3B The example shows the waveforms of relevant signals in the transient mode of heavy to light load.

[0025] Figure 4 The waveform diagram illustrates the relevant signals of the light to heavy load transient mode of the boost converter according to another embodiment of the present invention.

[0026] Figure 5 The example shows the waveforms of the relevant signals of the boost converter in light to heavy load transient mode without using the extended lower boundary and adapting to the transient voltage threshold.

[0027] Figure 6 The following is an example of waveform diagrams of relevant signals in the light to heavy load transient mode of a boost converter according to another embodiment of the present invention.

[0028] [Explanation of Key Component Symbols]

[0029] 100: Boost converter; 11: Transient detector

[0030] 12: Current Estimator 13: Controller

[0031] 14: Sensing Amplifier 21: Light to Heavy Load Transient Mode

[0032] 22: Generate Ith 23: Turn on the transistor

[0033] 24: IL>Ith? 25: Vo <Vth?

[0034] 26: Shutdown transistor 27: IL < Ith?

[0035] 28: Vo > VL? 31: Heavy to light load transient mode

[0036] 32: Generate Ith 33: Shutdown transistor

[0037] 34: Vo < VH? 35: Turn on transistor

[0038] 36: IL > Ith? Vi: Input voltage

[0039] Vo: Output voltage R: Resistor

[0040] L: Inductor D: Diode

[0041] M: Transistor C: Capacitor

[0042] TR: Transient mode Iout: Actual load current

[0043] Ith: Estimated load current Ith2: Adaptive load current

[0044] IL: Inductive current VH: Upper boundary

[0045] VL: Lower boundary VL2: Extended lower boundary

[0046] Vth: Transient voltage threshold Vth2: Adaptive transient voltage threshold Detailed implementation mode

[0047] Figure 1 A block diagram showing a boost converter 100 with a fast transient response according to an embodiment of the present invention. The boost converter 100 is used to boost the input voltage Vi to the output voltage Vo. For the sake of simplicity, only the transient mode loop is shown, but the steady state mode loop is omitted.

[0048] The boost converter 100 may include an inductor L (as an energy storage element) and a diode D, electrically connected in series between the input voltage Vi and the output voltage Vo. The boost converter 100 may include a transistor M, electrically connected between the interconnection node (of the inductor L and the diode D) and the ground. The boost converter 100 may include a capacitor C (as another energy storage element), electrically connected between the output voltage Vo and the ground.

[0049] In this embodiment, the boost converter 100 may include a transient detector 11, which detects transient mode TR by comparing the output voltage Vo with a steady-state window, wherein the steady-state window is located between the upper boundary VH and the lower boundary VL. When the output voltage Vo is not within the steady-state window, transient mode TR is detected.

[0050] The boost converter 100 of this embodiment may include a current estimator 12 to generate an estimated (steady-state) load current Ith based on changes in the output voltage Vo. For example, the estimated load current Ith may be generated based on the slope of the (falling) output voltage Vo during the initial period of a light-to-heavy load transient mode. In one embodiment, the transient detector 11 and the current estimator 12 may include an analog-to-digital converter to convert the analog output voltage Vo into a digital value to obtain the transient mode TR and the estimated load current Ith.

[0051] The boost converter 100 may include a (digital) controller 13 that controls the switching of transistor M based on the transient mode TR (detected by the transient detector 11) and the estimated load current Ith (estimated by the current estimator 12).

[0052] Figure 2A A flowchart showing the light-to-heavy load transient mode of the boost converter 100 according to an embodiment of the present invention is provided. Figure 2B The waveform diagrams of relevant signals in the transient mode of light to heavy load are shown.

[0053] When transient detector 11 detects that the output voltage Vo is below the lower boundary VL (of the steady-state window), boost converter 100 enters a light-to-heavy load transient mode (step 21). In step 22, current detector 12 generates an estimated load current Ith based on the change in output voltage Vo. Then, in step 23, controller 13 turns on transistor M, thus generating a rising inductor current IL and a falling output voltage Vo.

[0054] According to one feature of this embodiment, when the inductor current IL is greater than the estimated load current Ith (step 24), the output voltage Vo after a preset time Δt is recorded as the transient voltage critical Vth. The aforementioned inductor current IL can be measured by the sensing amplifier 14 across the resistor R (… Figure 1 The voltage is obtained by connecting the resistor R in series with the inductor L. When the output voltage Vo is lower than the transient voltage threshold Vth (step 25), the controller 13 turns off the transistor M (step 26), thus generating a decreasing inductor current IL and a rising output voltage Vo.

[0055] When the inductor current IL is lower than the estimated load current Ith (step 27) and the output voltage Vo is higher than the lower boundary VL (step 28) of the steady-state window, the boost converter 100 leaves the light-to-heavy load transient mode (to enter the steady-state mode); otherwise, the process returns to step 23.

[0056] According to the above embodiment, the transient voltage threshold Vth is dynamically determined (by controller 13), rather than being a fixed value obtained by looking up a table as described by Perez et al. Therefore, this embodiment avoids harmful oscillations.

[0057] Figure 3A A flowchart illustrating the heavy-to-light load transient mode of the boost converter 100 according to an embodiment of the present invention is shown. Figure 3B The example shows the waveforms of relevant signals in the transient mode of heavy to light load.

[0058] When transient detector 11 detects that the output voltage Vo is higher than the upper boundary VH (of the steady-state window), boost converter 100 enters a heavy-to-light load transient mode (step 31). In step 32, current detector 12 generates an estimated load current Ith based on the change in output voltage Vo. Then, in step 33, controller 13 turns off transistor M.

[0059] When the output voltage Vo is lower than the upper boundary VH (of the steady-state window) (step 34), the controller 13 turns on the transistor M (step 35).

[0060] When the inductor current IL is higher than the estimated load current Ith (step 36), the boost converter 100 leaves the heavy-to-light load transient mode.

[0061] Figure 4 The diagram illustrates waveforms of relevant signals in a light to heavy load transient mode of a boost converter 100 according to another embodiment of the present invention. In this embodiment, the transient voltage threshold Vth can be dynamically determined or obtained by looking up a table.

[0062] like Figure 4 As shown, when the actual load current Iout suddenly increases, the output voltage Vo gradually decreases. When the output voltage Vo falls below the lower boundary VL, the transient detector 11 detects a light to heavy load transient mode. Then, the current detector 12 generates an estimated load current Ith based on the change in output voltage Vo.

[0063] According to one feature of this embodiment, the steady-state window further has an extended lower boundary VL2, which is lower than the lower boundary VL, and there is a preset difference between the two. The boost converter 100 of this embodiment performs the light-to-heavy load transient mode in a manner similar to... Figure 2A The process is the same, but with the following differences.

[0064] In step 28, if the output voltage Vo is lower than the lower boundary VL but higher than the extended lower boundary VL2, then the transient voltage critical Vth is replaced by the adaptive transient voltage critical Vth2, wherein the adaptive transient voltage critical Vth2 is higher than the transient voltage critical Vth, and there is a preset difference between the two.

[0065] like Figure 4 As shown, in the light-to-heavy load transient mode, before the boost converter 100 enters the steady-state mode, the output voltage Vo has at least one first valley point, the value of which is the transient voltage critical Vth; then it has at least one second valley point, the value of which is the adaptive transient voltage critical Vth2 (which is higher than the first valley point). In this embodiment, the difference between the second valley point and the transient voltage critical Vth (i.e., the first valley point) is less than the height of the steady-state window (i.e., VH-VL).

[0066] Figure 5 The example shows the waveforms of the relevant signals for the boost converter 100 in light to heavy load transient mode without using the extended lower boundary VL2 and adapting to the transient voltage threshold Vth2. (Example:) Figure 5 As shown, in the light-to-heavy load transient mode, the output voltage Vo may exceed the upper boundary VH of the steady-state window, triggering the heavy-to-light load transient mode and thus slowing down the transient response. Therefore, this embodiment accelerates the light-to-heavy load transient by using an extended lower boundary VL2 and adapting to the transient voltage threshold Vth2.

[0067] Figure 6 The diagram illustrates waveforms of relevant signals in the light-to-heavy load transient mode of a boost converter 100 according to another embodiment of the present invention. In this embodiment, the transient voltage threshold Vth can be dynamically determined or obtained by looking up a table. The boost converter 100 of this embodiment performs the light-to-heavy load transient mode in a manner similar to... Figure 2A The process is the same, but with the following differences.

[0068] According to one feature of this embodiment, the current estimator 12 provides an adaptive load current Ith2, which is higher than the estimated load current Ith, with a preset difference between the two. In one embodiment, the adaptive load current Ith2 is obtained based on a lower boundary VL and a transient voltage threshold Vth (e.g., by looking up a table).

[0069] In step 25, in addition to comparing the output voltage Vo with the transient voltage threshold Vth, if the inductor current IL is higher than the adaptive load current Ith2, the controller 13 turns off the transistor M (step 26), thus generating a decreasing inductor current IL and a rising output voltage Vo.

[0070] like Figure 6As shown, in the light to heavy load transient mode, before the boost converter 100 enters the steady-state mode, the output voltage Vo has at least one first valley point, the value of which is the transient voltage critical Vth; then it has at least one second valley point, the value of which is higher than the first valley point. Furthermore, in this embodiment, the difference between the second valley point and the transient voltage critical Vth (i.e., the first valley point) is less than the height of the steady-state window (i.e., VH-VL).

[0071] This embodiment accelerates light-to-heavy load transients by using the adaptive load current Ith2. Without Ith2, the output voltage Vo might exceed the upper boundary VH of the steady-state window, triggering a heavy-to-light load transient mode and thus slowing down the transient response. Figure 5 As shown.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A boost converter, characterized in that, Include: The inductor and diode are connected in series between the input voltage and the output voltage. A transistor, electrically coupled to the interconnection node between the inductor and the diode; and The controller controls the switching of the transistor based on the transient mode and the estimated load current. and A transient detector detects the transient mode by comparing the output voltage with a steady-state window, wherein the steady-state window is located between the upper and lower boundaries; Before leaving the light-to-heavy load transient mode, the output voltage has at least one first valley point, which is the transient voltage critical point; then it has at least one second valley point, which is higher than the first valley point. The controller performs the following steps in this light to heavy load transient mode: (a) When the light to heavy load transient mode is detected, turn on the transistor; (b) When the inductor current is greater than the estimated load current and the output voltage is lower than the transient voltage threshold, the transistor is turned off; and (c) When the inductor current is lower than the estimated load current and the output voltage is higher than the lower boundary, leave the light to heavy load transient mode; otherwise, return to step (b).

2. The boost converter according to claim 1, characterized in that, It also includes: A capacitor is electrically connected between the output voltage and ground.

3. The boost converter according to claim 1, characterized in that, It also includes: A current estimator generates the estimated load current based on changes in the output voltage.

4. The boost converter according to claim 3, characterized in that, The estimated load current is generated based on the slope of the output voltage during the initial period of the light to heavy load transient mode.

5. The boost converter according to claim 1, characterized in that, When the inductor current exceeds the estimated load current, the output voltage after a preset time is recorded as the transient voltage critical.

6. The boost converter according to claim 1, characterized in that, The steady-state window has an extended lower boundary that is lower than the lower boundary, with a preset difference between the two. If the output voltage is lower than the lower boundary but higher than the extended lower boundary, the transient voltage threshold is replaced by an adaptive transient voltage threshold, wherein the adaptive transient voltage threshold is higher than the transient voltage threshold, with a preset difference between the two.

7. The boost converter according to claim 6, characterized in that, The value of the second valley point is the critical value of the adaptive transient voltage.

8. The boost converter according to claim 1, characterized in that, It also provides an adaptive load current that is higher than the estimated load current, with a preset difference between the two; if the inductor current is higher than the adaptive load current, the controller turns off the transistor.

9. The boost converter according to claim 8, characterized in that, The adaptive load current is obtained based on the lower boundary and the transient voltage threshold.

10. The boost converter according to claim 8, characterized in that, The difference between the second valley point and the transient voltage threshold is less than the height of the steady-state window.

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