CN104682679A - Power converter and its slope detection controller and method - Google Patents

Abstract

The present invention discloses a power converter and a slope detection controller and method thereof. The power converter includes an output stage, a pulse width modulation control unit and a slope detection controller, wherein the output stage includes a first switch. The pulse width modulation control unit is coupled to the output stage and controls the operation of the first switch of the output stage. The slope detection controller is coupled to the pulse width modulation control unit and generates a slope detection signal according to the output voltage of the power converter, and generates a control signal according to the slope detection signal, so that the pulse width modulation control unit controls the first switch to be closed.

Description

Power converter and its slope detection controller and method

technical field

The present invention relates to a power converter, and in particular to a power converter and its slope detection controller and method.

Background technique

FIG. 1 is a circuit diagram of a known DC-DC converter. As shown in FIG. 1 , the DC-DC converter 100 is used to convert an input voltage Vin into an output voltage Vout through an output stage 110 . The DC-DC converter 100 feeds back the change of the output voltage Vout to the PWM control unit 120 to control the operation of the output stage 110 so that the output voltage Vout can be adjusted to a rated output voltage.

FIG. 2 is a schematic diagram of waveforms of a known DC-DC converter at the moment of load change. Please refer to FIG. 1 and FIG. 2 together. Under normal operation of the DC-DC converter 100, as shown in T1 interval of FIG. 2, the DC-DC converter 100 will maintain its output voltage Vout within a predetermined range of the rated output voltage. Inside. When the load changes from a heavy load to a light load, because the circuit response speed of the DC-DC converter 100 cannot keep up with the load transient (load transient), so in the T2 interval of FIG. 2 , the DC-DC converter The inductor current IL provided by 100 is still more than the required load current Iload, so the above-mentioned excess inductor current IL will charge the output capacitor Cout, so that the output voltage Vout will increase and cause the output voltage Vout to exceed the preset rated output voltage This phenomenon is called overshoot. However, the above situation is undesirable in product application.

Contents of the invention

In view of this, the present invention provides a power converter and its slope detection controller and method for the power converter, so as to solve the problems mentioned in the background art.

The invention provides a slope detection controller of a power converter, which includes a slope detection unit and an output control unit. The above-mentioned slope detection unit receives the output voltage of the power converter, and generates a slope detection signal according to the output voltage. The output control unit is coupled to the slope detection unit, and provides a control signal according to the slope detection signal to control the power converter.

In an embodiment of the present invention, when the slope detection signal exceeds a preset value, the output control unit generates a control signal.

In an embodiment of the invention, the control signal is used to turn off the first switch of the power converter.

In an embodiment of the invention, the control signal is used to cut off the on-time signal of the time signal generator of the power converter.

In an embodiment of the invention, the control signal is used to cut off the PWM signal of the power converter.

The invention provides a power converter, which includes an output stage, a pulse width modulation control unit, and a slope detection controller. The aforementioned output stage includes a first changeover switch. The aforementioned PWM control unit is coupled to the output stage, and controls the operation of the first switch of the output stage. The slope detection controller is coupled to the pulse width modulation control unit, and generates a slope detection signal according to the output voltage of the power converter, so as to generate a control signal according to the slope detection signal, so that the pulse width modulation control unit controls The first toggle switch is off.

In an embodiment of the present invention, the output stage further includes a second switching switch, the first switching switch may also be called an upper bridge switch, and the second switching switch may also be called a lower bridge switch.

In an embodiment of the present invention, the PWM control unit includes a driver, and the slope detection controller is coupled to the driver so that the control signal controls the driver to turn off the first switch.

In an embodiment of the present invention, the pulse width modulation control unit includes a timing signal generator, and the slope detection controller is coupled to the timing signal generator, so that the control signal controls the timing signal generator to stop providing the on-time signal, so as to Turn off the first toggle switch.

In an embodiment of the present invention, the PWM control unit includes a PWM generator, and the slope detection controller is coupled to the PWM generator so that the control signal controls the generation of the PWM The controller stops providing the pulse width modulation signal, so as to close the first switching switch.

In one embodiment of the present invention, the pulse width modulation generator includes an error amplifier and a first comparator, and the slope detection controller is coupled between the error amplifier and the first comparator, so as to use a control signal to affect the error The error signal of the amplifier is used to stop the PWM generator from providing the PWM signal.

In one embodiment of the present invention, the pulse width modulation generator includes an error amplifier, a first comparator and a ramp signal generator, the first input end of the first comparator is coupled to the error amplifier, and the first comparator The second input terminal is coupled to the ramp signal generator, and the slope detection controller is coupled to the ramp signal generator, so as to use the control signal to affect the ramp signal of the ramp signal generator to stop the pulse width modulation generator Provides a pulse width modulated signal.

In one embodiment of the present invention, the slope detection controller includes a slope detection unit and an output control unit, the slope detection unit is a differential circuit to provide a slope detection signal, and the output control unit generates a control signal according to the slope detection signal .

The present invention proposes a slope detection control method of a power converter, which includes: receiving the output voltage of the power converter; providing a slope detection signal according to the output voltage; and generating a control signal according to the slope detection signal to control the power converter .

In the aforementioned slope detection control method, the control signal is generated when the slope detection signal exceeds a preset value.

To sum up, the detection control method of the power converter and the slope detection controller provided by the present invention uses the detection of the output voltage slope and the open-loop control method to suppress the output voltage overshoot phenomenon, so as to improve the system stability.

The advantages and spirit of the present invention can be further understood through the following detailed description of the invention and the accompanying drawings.

Description of drawings

FIG. 1 illustrates a circuit diagram of a known DC-DC converter.

FIG. 2 is a schematic diagram of waveforms of a known DC-DC converter at the moment of load change.

FIG. 3 is a schematic circuit diagram of a power converter according to an embodiment of the invention.

FIG. 4 is a schematic circuit diagram of a slope detection controller according to an embodiment of the present invention.

Figure 5 shows the transient response of the load changing from heavy load to light load after adding the slope detection controller.

FIG. 6A is a schematic circuit diagram of the first embodiment of the control mode of the slope detection controller according to the present invention.

FIG. 6B is a schematic diagram of a driver circuit according to the first embodiment of the control mode of the slope detection controller of the present invention.

FIG. 7A is a schematic circuit diagram of a second embodiment of the control method of the slope detection controller according to the present invention.

FIG. 7B is a schematic diagram of a time signal generator circuit according to a second embodiment of the control mode of the slope detection controller of the present invention.

FIG. 8A is a schematic circuit diagram of a third embodiment of the control method of the slope detection controller according to the present invention.

FIG. 8B is a schematic diagram of a control error signal circuit according to a third embodiment of the control mode of the slope detection controller of the present invention.

FIG. 8C is a schematic diagram of a control ramp signal circuit according to a third embodiment of the control mode of the slope detection controller of the present invention.

FIG. 9 illustrates a slope detection control method of a power converter according to an embodiment of the present invention.

Description of main component symbols:

100, 300 power converter

110, 31 output stages

120, 32 pulse width modulation control unit

33 slope detection controller

121, 321 error amplifier

122, 322 first comparator

123, 323 time signal generator

124, 324 drives

325 Pulse Width Modulation Generator

326 Ramp Wave Signal Generator

329 compensation unit

41 slope detection unit

42 output control unit

Cout output capacitance

ctrl control signal

ERR error signal

ESR equivalent series resistance

IL inductor current

Iload load current

Vin input voltage

Vout output voltage

V+ positive voltage

UG first switch signal

LG second switch signal

PHASE phase node

pwm pulse width modulated signal

REF reference signal

ramp ramp signal

SD slope detection signal

STL default value

TON on-time signal

SW1 first toggle switch

C capacitance

nand non-and gate

S905～S920 process steps

SW2 second toggle switch

R resistance

Inv inverter

DFF Type D flip-flop

Detailed ways

Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In addition, elements/components with the same or similar numbers used in the drawings and embodiments are used to represent the same or similar parts.

In the following embodiments, when an element is referred to as being “connected” or “coupled” to another element, it may be directly connected or coupled to the other element, or there may be intervening elements. The term "circuitry" may refer to at least one element or a plurality of elements, or elements that are actively and/or passively coupled together to provide a suitable function. The term "signal" may refer to at least one current, voltage, load, temperature, data or other signal. The ramp signal can also be a ramp-like signal, a triangular wave signal or a sawtooth wave signal, which can be a ramp wave in the form of a repeating-falling wave or a ramping wave in the form of a repeating-rising wave, depending on the application.

A preferred embodiment of the present invention is a power converter. In this embodiment, the power converter proposed by the present invention is applied in a power integrated circuit (Power IC), but not limited thereto.

Please refer to FIG. 3 , which is a schematic circuit diagram of a power converter according to an embodiment of the present invention. As shown in FIG. 3 , the power converter 300 includes an output stage 31 , a PWM control unit 32 and a slope detection controller 33 . In this embodiment, the PWM control unit 32 also includes an error amplifier 321, a first comparator 322, a time signal generator 323, and a driver 324; the output stage 31 also includes a first switching switch SW1 and a second switching switch SW2; the first switching switch SW1 can also be called the upper bridge switch, and the second switching switch SW2 can also be called the lower bridge switch. In other embodiments, the output stage 31 may also include only one switching switch, which is combined with components such as diodes or inductors, but is not limited thereto.

The first switch SW1 in the output stage 31 is coupled to the input voltage Vin and the driver 324 . The second switch SW2 in the output stage 31 is coupled to the driver 324 and the ground. There is also a phase node PHASE between the first switch SW1 and the second switch SW2, and the phase node PHASE is coupled to one end of the output inductor. In this embodiment, the phase node PHASE is also coupled to the driver 324 . In other embodiments, the phase node PHASE may not be coupled to the driver 324 , and the invention is not limited thereto.

The error amplifier 321 of the PWM control unit 32 is coupled to the other end of the output inductor. In other embodiments, the error amplifier 321 can also be coupled to the other end of the output inductor through a voltage dividing unit. In addition, the error amplifier 321 is also coupled to a reference voltage REF, and the magnitude of the reference voltage REF may be related to the rated output voltage of the power converter 300 . In this embodiment, the error amplifier 321 provides a voltage-type error signal ERR. In other embodiments, the error amplifier 321 can also be replaced by a transconductance amplifier (GM) to provide a current-type error signal ERR. limit.

An input terminal of the first comparator 322 is coupled to the output terminal of the error amplifier 321 . In this embodiment, the output of the error amplifier 321 is provided to the first comparator 322 after being compensated by the compensation unit 329 . The other input terminal of the first comparator 322 is used for receiving the ramp signal ramp. The first comparator 322 provides a trigger signal according to the comparison result. The timing signal generator 323 is respectively coupled to the first comparator 322 and the driver 324 . The timing signal generator 323 provides the on-time signal TON to the driver 324 according to the above trigger signal, so as to control the operation of the output stage 31 . Through the coupling of the above components/circuits, the PWM control unit 32 can be coupled to the output stage 31 and control the operation of the output stage 31 .

In an embodiment of the present invention, the slope detection controller 33 is coupled to the PWM control unit 32, and controls the PWM control unit 32 according to the slope of the output voltage Vout of the power converter 300, so as to The operation of at least one switch of the output stage 31 is further controlled.

FIG. 4 is a schematic circuit diagram of a slope detection controller according to an embodiment of the present invention. For its description, please refer to FIG. 3 and FIG. 4 together. The slope detection controller 33 includes a slope detection unit 41 and an output control unit 42 . The slope detection unit 41 is respectively coupled to the output terminal of the power converter 300 and the output control unit 42 to receive the output voltage Vout of the power converter 300 and generate a slope detection signal SD according to the slope of the output voltage Vout. In this embodiment, the slope detection unit 41 is a differential circuit. In other embodiments, the slope detection unit 41 may also be replaced by other circuits capable of detecting slopes, and the invention is not limited thereto.

The output control unit 42 is a comparator, one input terminal receives the slope detection signal SD, and the other input terminal receives a reference signal with a preset value (slope trigger level), when the slope detection signal exceeds the preset value , the output control unit 42 will generate the control signal ctrl to control the power converter 300 .

As shown in FIG. 5 , in the interval T2, when the load transition is transient (load transient), the output control unit 42 can generate a control signal ctrl by detecting the slope of the output voltage Vout to control the first switch of the output stage 31 SW1, so that the inductor current IL no longer charges the output capacitor Cout, so as to solve the overshoot problem of the output voltage Vout. In FIG. 5 , the dotted line is the original response of the known DC-to-DC converter, and the solid line is the improved circuit response of this embodiment.

In the present invention, the control signal ctrl provided by the slope detection controller 33 can be provided to each component in the pulse width modulation control unit 32, so as to influence the pulse width modulation control unit 32 through the control signal ctrl operation, and then turn off (turn off) the first switching switch SW1 of the output stage 31, so that the output voltage Vout will not continue to rise.

6A-8C are circuit schematic diagrams of various embodiments of the control method of the slope detection controller of the present invention. FIG. 6A is a schematic circuit diagram of the first embodiment of the control mode of the slope detection controller according to the present invention. In FIG. 6A, the slope detection controller 33 is coupled to the driver 324 of the PWM control unit 32 to provide the control signal ctrl to the driver 324, so that the driver 324 outputs the first switch signal UG to the first switch The switch SW1 is forcibly turned off (turn off) the first switching switch SW1, causing the inductor current IL to stop charging the output capacitor Cout.

FIG. 6B is a schematic diagram of a driver circuit according to the first embodiment of the control mode of the slope detection controller of the present invention. In FIG. 6B, when the control signal ctrl is, for example, at a high level, the driver 324 will output the first switch signal UG to the first switch of the output stage 31 regardless of whether the time signal TON of the time signal generator 323 is on or off. Switch SW1 to close the first switch SW1. That is, the priority of the control signal ctrl is higher than that of the on-time signal TON.

FIG. 7A is a schematic circuit diagram of a second embodiment of the control method of the slope detection controller according to the present invention. In FIG. 7A, the slope detection controller 33 is coupled to the timing signal generator 323 to provide a control signal ctrl to control the timing signal generator 323, so that the timing signal generator 323 stops providing the on-time signal (TON) to the driver. 324, and then forcibly turn off (turn off) the first switching switch SW1, so that the inductor current IL stops charging the output capacitor Cout.

7B is a schematic circuit diagram of the time signal generator according to the second embodiment of the control mode of the slope detection controller of the present invention. In FIG. 7B, when the first comparator 322 provides a trigger signal to the timing signal generator 323, the timing signal generator 323 provides a constant on-time signal TON (or a constant off-time signal) to the driver 324 according to the trigger signal. , to control the operation of the output stage 31. However, when the slope detection controller 33 provides the control signal ctrl to the timing signal generator 323 , the timing signal generator 323 stops providing the on-time signal TON to the driver 324 according to its internal circuit logic. That is to say, the control signal ctrl provided by the slope detection controller 33 can forcibly stop the generation of the on-time signal TON. That is, the control signal ctrl has the highest priority.

FIG. 8A is a schematic circuit diagram of a third embodiment of the control method of the slope detection controller according to the present invention. In FIG. 8A , the PWM control unit 32 further includes a PWM generator 325 . The slope detection controller 33 is coupled to the pulse width modulation generator 325 of the pulse width modulation control unit 32 to provide a control signal ctrl to control the pulse width modulation generator 325 to stop providing the pulse width modulation signal pwm to The driver 324 is forcibly cut-off the ongoing conduction period (Ton), so that the driver 324 turns off the first switch SW1.

FIG. 8B is a schematic diagram of a control error signal circuit according to a third embodiment of the control mode of the slope detection controller of the present invention. In FIG. 8B , the PWM generator 325 further includes an error amplifier 321 and a first comparator 322 . The slope detection controller 33 is coupled between the error amplifier 321 and the first comparator 322 for providing a control signal ctrl to control the error signal ERR of the error amplifier 321 to control the PWM generator 325 to stop providing pulses Width modulating the signal pwm to forcibly turn off the ongoing conduction period, so that the driver 324 turns off the first switch SW1. In this embodiment, the control signal ctrl controlling the error signal ERR means that the control signal ctrl can make the error signal ERR provided by the error amplifier 321 pull up or down, so as to affect the pulse width modulation signal pwm produce. In other embodiments, the control signal ctrl and the error signal ERR may also be summed or other various operations are performed, and the present invention is not limited thereto.

FIG. 8C is a schematic diagram of a control ramp signal circuit according to a third embodiment of the control mode of the slope detection controller of the present invention. In FIG. 8C , the PWM generator 325 further includes a ramp signal generator 326 . A first input terminal of the first comparator 322 is coupled to the error amplifier 321 , and a second input terminal of the first comparator 322 is coupled to the ramp signal generator 326 . The slope detection controller 33 is coupled to the ramp signal generator 326 to provide a control signal ctrl to control the ramp signal ramp of the ramp signal generator 326, so as to control the PWM generator 325 to stop providing pulse width modulation. Change the signal pwm to forcibly cut off the conduction period in progress, so that the driver 324 turns off the first switch SW1. Similar to FIG. 8B, in FIG. 8C, the control signal ctrl controlling the ramp signal ramp means that the control signal ctrl can make the ramp signal ramp up or down to affect the pulse width modulation signal pwm produce. In other embodiments, the control signal ctrl and the ramp signal ramp may also be summed or other various calculations are performed, and the present invention is not limited thereto.

Another specific embodiment according to the present invention is a slope detection control method for a power converter. Please refer to FIG. 9 , which is a flow chart of the slope detection control method of the power converter according to this embodiment. For its description, please refer to FIG. 3 and FIG. 4 together. In step S905 , the slope detection unit 41 is respectively coupled to the output terminal of the power converter 300 and the output control unit 42 to receive the output voltage Vout of the power converter. In step S910, the method uses the slope detection unit 41 to provide the slope detection signal SD according to the output voltage Vout. In step S915, the method uses the output control unit 42 to generate the control signal ctrl. When the slope detection signal SD exceeds the preset value STL, the method generates the control signal ctrl according to the slope detection signal SD. In step S920 , the above method provides a control signal ctrl to control the power converter 300 .

Compared with the background technology, the power converter and its slope detection controller and method according to the present invention can detect the slope of the output voltage and use an open-loop control method at the moment when the load current is converted from a heavy load to a light load The conduction period in progress is directly cut off to effectively suppress the phenomenon of output voltage overshoot, so that the output voltage of the power converter will not continue to overshoot.

Through the above detailed description of the preferred embodiments, it is hoped that the features and spirit of the present invention can be described more clearly, and the scope of the present invention is not limited by the preferred embodiments disclosed above. On the contrary, the intention is to cover various modifications and equivalent arrangements within the scope of the appended claims of the present invention.

Claims (15)

1. A slope detection controller of a power converter, characterized in that the above-mentioned slope detection controller includes: a slope detection unit, receiving an output voltage of the power converter, and generating a slope detection signal according to the output voltage; and An output control unit is coupled to the slope detection unit and provides a control signal according to the slope detection signal to control the power converter. 2. The slope detection controller according to claim 1, wherein the output control unit generates the control signal when the slope detection signal exceeds a preset value. 3. The slope detection controller as claimed in claim 1, wherein the control signal is used to turn off a first switch of the power converter. 4. The slope detection controller as claimed in claim 1, wherein the control signal is used to cut off a turn-on time signal of a time signal generator of the power converter. 5. The slope detection controller as claimed in claim 4, wherein the control signal is used to cut off a pulse width modulation signal of the power converter. 6. A power converter, characterized in that the above power converter comprises: an output stage including a first switch; a pulse width modulation control unit, coupled to the output stage, and controls the operation of the first switch of the output stage; and A slope detection controller, coupled to the above-mentioned pulse width modulation control unit, is used to generate a slope detection signal according to an output voltage of the above-mentioned power converter, and generate a control signal according to the above-mentioned slope detection signal, so that The pulse width modulation control unit controls the first switching switch to be turned off. 7. The power converter as claimed in claim 6, wherein the output stage further comprises a second switch, the first switch is a high-side switch, and the second switch is a low-side switch. 8. The power converter according to claim 6, wherein the pulse width modulation control unit comprises a driver, the slope detection controller is coupled to the driver, so that the control signal controls the driver to turn off the first One toggle switch. 9. The power converter according to claim 6, wherein the pulse width modulation control unit includes a timing signal generator, and the slope detection controller is coupled to the timing signal generator so that the control signal The above-mentioned time signal generator is controlled to stop providing a conduction time signal, so as to close the above-mentioned first switch. 10. The power converter according to claim 6, wherein the PWM control unit comprises a PWM generator, and the slope detection controller is coupled to the PWM generator device, so that the control signal controls the pulse width modulation generator to stop providing a pulse width modulation signal, so as to close the first switching switch. 11. The power converter according to claim 10, wherein said PWM generator comprises an error amplifier and a first comparator, said slope detection controller is coupled to said error amplifier and said Between the first comparator, the control signal is used to affect an error signal of the error amplifier so that the PWM generator stops providing the PWM signal. 12. The power converter according to claim 10, wherein the above-mentioned PWM generator comprises an error amplifier, a first comparator and a ramp signal generator, and one of the above-mentioned first comparators The first input end is coupled to the error amplifier, a second input end of the first comparator is coupled to the ramp signal generator, and the slope detection controller is coupled to the ramp signal generator to utilize the control signal A ramp signal is used to affect the ramp signal generator to stop the PWM generator from providing the PWM signal. 13. The power converter according to claim 6, wherein the slope detection controller comprises a slope detection unit and an output control unit, the slope detection unit is a differential circuit to provide a slope detection signal, the above-mentioned output control unit generates the above-mentioned control signal according to the above-mentioned slope detection signal. 14. A slope detection control method for a power converter, characterized in that the slope detection control method includes the following steps: receiving an output voltage of the power converter; providing a slope detection signal according to the above output voltage; and A control signal is generated according to the slope detection signal to control the power converter. 15. The slope detection control method according to claim 14, wherein the control signal is generated when the slope detection signal exceeds a preset value.