CN110971122A

CN110971122A - Multi-mode power converter

Info

Publication number: CN110971122A
Application number: CN201811141262.4A
Authority: CN
Inventors: 王三辅
Original assignee: Pudeng Co Ltd
Current assignee: Pudeng Co Ltd
Priority date: 2018-09-28
Filing date: 2018-09-28
Publication date: 2020-04-07
Also published as: TW202013865A; TWI669894B

Abstract

A multi-mode power converter comprising: the energy storage device comprises an energy storage element, a first switch, a second switch, a third switch, a fourth switch, a mode control device and a control device. The mode control device is coupled with the input voltage, judges the voltage range of the input voltage according to the first voltage and the second voltage and outputs first to third mode signals respectively corresponding to a direct mode, a buck mode and a boost mode. The control device outputs first to fourth control signals according to the first to third mode signals to respectively control the first to fourth switches, so that the multi-mode power converter respectively operates in a direct-current mode, a buck mode or a boost mode. In the through mode, the first and the second switches are completely turned on, and the second and the fourth switches are completely turned off.

Description

Multi-mode power converter

Technical Field

The present invention relates to a power converter, and more particularly, to a power converter having multiple modes.

Background

At present, most electronic products or information products use a dc power source as an input source, and usually adopt a power converter (e.g., a buck-boost power converter) with a buck-boost function as a power supply device. The power converter with the voltage boosting and reducing function has the advantages that an input direct-current power supply which changes in a large range can be converted into a rated output power supply; therefore, even under the condition of an unstable input source, the electronic product can be provided with a stable rated output power supply, so that the electronic product can obtain the power required by stable operation. The design of the Power converter with the buck-boost function can be applied to a Power Adapter (Power Adapter) with a Universal Serial Bus (USB), and the like.

In current power converter designs, the power converter can be operated in a Boost Mode (Boost Mode) and a Buck Mode (Buck Mode). When the input voltage is greater than the output voltage, the power converter starts a voltage reduction mode; conversely, when the input voltage is less than the output voltage, the power converter enters a boost mode. However, when the input voltage received by the power converter is too close to or equal to the output voltage, the control device of the power converter is continuously switched between the boost mode and the buck mode to maintain a stable output voltage. However, the power converter generates significant switching loss during the switching process between the boost mode and the buck mode, so that the operating efficiency of the power converter is greatly reduced. In addition, Switching Loss (Switching Loss) in the buck-boost power converter is also increased due to Switching between two modes of the power converter. Furthermore, in order to switch between the boost mode and the buck mode, the control device (such as a cpu, a processor, a microprocessor, etc.) in the power converter needs to continuously change the output control signal, so that the operating temperature of the control device is increased and the control device is damaged.

Disclosure of Invention

The present invention provides a multi-mode power converter having a through mode, wherein the power converter performs the through mode when the input voltage received by the multi-mode power converter is too close to or equal to the output voltage. Thereby, the above-described problems are solved.

A multi-mode power converter comprising: the energy storage device comprises an energy storage element, a first switch, a second switch, a third switch, a fourth switch, a mode control device and a control device. The energy storage element has a first end and a second end. The first switch is coupled to the input voltage and the first terminal. The second switch is coupled to the first terminal and the reference node. The third switch is coupled to the second terminal and the output node. The fourth switch is coupled to the second terminal and the reference node. The mode control device is coupled to the input voltage and determines a voltage range of the input voltage according to the first voltage and the second voltage. The mode control device outputs first to third mode signals respectively corresponding to a through mode, a buck mode, and a boost mode according to the determination result. The first voltage value is greater than the rated output voltage of the multi-mode power converter, and the second voltage value is less than the rated output voltage. The control device is coupled to the mode control device and the first to fourth switches, and outputs first to fourth control signals according to the first to third mode signals to control the first to fourth switches to be alternately turned on/off or completely turned on/off, so that the multi-mode power converter operates in a direct-current mode, a buck mode or a boost mode. In the through mode, the first and third switches are fully on, and the second and fourth switches are fully off.

Drawings

Fig. 1 is a circuit diagram of a power converter shown according to a related art method of switching control.

Fig. 2 is a circuit diagram of a power converter according to an embodiment of the invention.

Fig. 3 is a circuit diagram of a power converter according to some other embodiments of the invention.

Fig. 4 is a waveform diagram of a power converter according to an embodiment of the invention.

Fig. 5 is a waveform diagram of a power converter according to another embodiment of the invention.

Fig. 6 is a diagram of method steps for a multi-mode power converter according to an embodiment of the invention.

Description of reference numerals:

100: power converter

122-124: switch with a switch body

140: energy storage element

162. 164: switch with a switch body

170: voltage divider circuit

172. 174, and (3) a step of: resistance (RC)

180: comparison device

200: multi-mode power converter

222: first switch

224: second switch

240: energy storage element

242: first end

244: second end

262: third switch

262 a: parasitic diode

264: the fourth switch

266: rectifying element

268: third switch

280: mode control device

282: comparison device

284: reference voltage circuit

290: control device

500: DC voltage source

600: load(s)

Vin: input voltage

Vout: output voltage

VFB: voltage feedback signal

S0: mode signal

S1-S4: first to fourth control signals

S5: a fifth control signal

Vref 1: first voltage

Vref 2: second voltage

N: output node

300: method of producing a composite material

310 to 366: step (ii) of

Detailed Description

The present invention is described with reference to the drawings, wherein like reference numerals are used to refer to similar or equivalent elements throughout the several views. The drawings are not drawn to scale but are merely illustrative of the invention. Several aspects of the invention are described below and with reference to example applications for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One skilled in the relevant art will readily recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods. In other instances, structures or operations that are present are not shown in detail to avoid obscuring the invention. The present invention is not limited by the illustrated ordering of acts or events, as some acts may occur in different orders and/or concurrently with other acts or events. Moreover, not all illustrated acts or events are required to be implemented in accordance with the methodologies of the present invention.

The following description is an example of the present invention. The general principles of the present invention are intended to be illustrative, but not limiting, of the scope of the invention, which is defined by the claims.

Conventionally, a power converter configures four identical power transistors as switching switches, and can operate only in a Boost Mode (Boost Mode) or a Buck Mode (Buck Mode). In the step-up mode or the step-down mode, since the control device generally cannot provide a Pulse Width Modulation (PWM) signal with a Duty ratio (Duty) of 100% to the power transistor, so that the switch in the power converter with the step-up and step-down functions cannot be completely turned on, when the input voltage is close to or equal to the output voltage, the step-up and step-down power converter can only be switched between the step-up mode and the step-down mode continuously.

Therefore, when the output voltage is close to or equal to the input voltage, the conventional power converter has a problem of low operating efficiency, because the temperature of the control device is increased when the control device is continuously switched between the boost mode and the buck mode, which makes the control device prone to malfunction or damage. Furthermore, the constant alternating on and off operation of the switch causes significant switching losses. The following description will be made of the reason for the reduction of the operation efficiency of the conventional power converter.

Fig. 1 is a circuit diagram of a power converter 100 shown according to a prior art method of switching control. Such as

As shown in fig. 1, the conventional power converter 100 includes a switch 122, a switch 124, an energy storage element 140, a switch 162, a switch 164, a voltage divider 170, a comparator 180, and a controller 190. The

switches

122 and 124 are used for receiving and switching an input voltage Vin from the dc voltage source 500, and the

switches

162 and 164 generate an output voltage Vout for the load 600. The voltage divider 170 is composed of a resistor 172 and a resistor 174, and divides the output voltage Vout to generate the voltage feedback signal VFB. The comparator 180 is used for receiving the input voltage Vin and the voltage feedback signal VFB for comparison. The comparing device 180 recognizes the magnitude of the output voltage Vout by receiving the voltage feedback signal VFB, and compares the magnitude of the voltage feedback signal VFB with the magnitude of the input voltage Vin. The comparison means 180 outputs the result of the comparison to the control means 190. The output comparison result comprises a boosting mode signal and a reducing mode signal. The control device 190 outputs the first to fourth control signals S1-S4 according to the comparison result of the comparison device 180, and controls the states of the

switches

122 and 124 and the

switches

162 and 164, respectively, so that the conventional power converter 100 can operate in the buck mode or the boost mode. The

switches

122, 124, 162, and 164 in the conventional power converter 100 are all N-type metal oxide semiconductor field effect transistors (N-type MOSFETs).

The conventional power converter 100 operates in the buck mode and the boost mode as follows: when the comparing device 180 detects that the voltage feedback signal VFB is greater than the input voltage Vin, it indicates that the output voltage Vout of the power converter 100 exceeds the input voltage Vin, and the power converter 100 enters the boost mode. When the comparing device 180 detects that the voltage feedback signal VFB is less than the input voltage Vin, indicating that the output voltage of the power converter 100 is lower than the input voltage Vin, the power converter 100 enters the buck mode.

When the voltage feedback signal VFB of the conventional power converter 100 is identified by the comparing device 180 to be equal to the input voltage Vin, the comparison result output by the comparing device 180 continuously alternates between the boost mode signal and the buck mode signal for stable output because the output voltage Vout is too close to the input voltage Vin. Therefore, the power converter 100 operates in the boost mode and the buck mode alternately, which causes the power converter 100 to generate significant switching loss. In addition, the control device must continuously change the output control signals S1-S4 to make the power converter 100 perform the alternating operation of the step-up mode and the step-down mode, which makes the control device easily in an overheat state and damaged.

Unlike the conventional power converter 100, the present invention provides a multi-mode power converter with a through mode (By PassMode), and the multi-mode power converter includes two identical P-type MOSFETs and two identical N-type MOSFETs as switches. The method of the present invention will be described in detail below, which can avoid switching between the boost mode and the buck mode when the output voltage is close to or equal to the input voltage, so as to improve the operating efficiency of the multi-mode power converter and protect the control device.

Fig. 2 is a circuit diagram of a multi-mode power converter 200 according to an embodiment of the invention. As shown in fig. 2, the multi-mode power converter 200 includes a first switch 222, a second switch 224, a third switch 262, a fourth switch 264, an energy storage element 240, a mode control device 280, and a control device 290. The mode control device 280 also includes a comparison device 282 and a reference voltage circuit 284. The energy storage element 240, such as an inductor, has a first end 242 and a second end 244. The first switch 222 is coupled to the input voltage Vin and the first terminal 242 of the energy storage element 240. The second switch 224 is coupled to the first terminal 242 of the energy storage element 240 and the reference node group. The third switch 262 couples the second terminal 244 of the energy storage device 240 and the output node N. The fourth switch 264 couples the second terminal 244 and the reference node group. The comparison device 282 of the mode control device 280 is coupled to the input voltage Vin, and determines a voltage range of the input voltage Vin according to the first voltage Vref1 and the second voltage Vref2 of the reference voltage circuit 284. The comparison device 282 outputs first to third mode signals corresponding to the through mode, the buck mode, and the boost mode, respectively, according to the determination result. The Comparator 282 includes a plurality of circuits with comparison functions, such as comparators (comparators) or Error amplifiers (Error amplifiers), for determining the range of the input voltage Vin, which can be easily understood and implemented by those skilled in the art.

The reference Voltage circuit 284 in the mode control device 280 may set the values of the first Voltage Vref1 and the second Voltage Vref2 according to a Rated output Voltage (Rated Voltage) of the multi-mode power converter 200. The first voltage value Vref1 is greater than the rated output voltage of the multi-mode power converter, and the second voltage Vref2 is less than the rated output voltage. For example, if the rated output voltage of the multi-mode power converter 200 is 12V, the first voltage Vref1 can be set to 12.1-12.5V, and the second voltage Vref2 can be set to 11.5-11.9V. However, the present invention is not limited thereto. In addition, the rated output voltage of the multi-mode power converter 200 is determined according to the input specification of the load 600, and thus can be changed according to actual requirements. In fig. 2, the voltage divider 170 divides the output voltage Vout to form a voltage feedback signal VFB, and the mode control device 280 determines the magnitude of the output voltage Vout according to the voltage feedback signal VFB. The mode control device 280 has an error amplifier (not shown), compares the voltage feedback signal VFB with a reference voltage level (not shown), and the mode control device 280 outputs a fifth control signal S5 to the control device 290 according to the comparison result. The control device 290 can adjust and control the pulse widths of the output control signals S1-S4 according to the fifth control signal S5, so as to control the states of the first to fourth switches (222, 224, 262, 264). Thus, the output voltage Vout can be stabilized. Since the technique of the mode control device 280 utilizing the error amplifier to ensure the output voltage Vout is stable is understood by those skilled in the art, the present disclosure does not describe the connection manner of the error amplifier in the mode control device 280 and particularly the operation principle thereof.

The comparison device 282 of the mode control device 280 compares the input voltage Vin with the first voltage Vref1 and the second voltage Vref2, and then outputs a mode signal S0 to the control device 290 according to the comparison result. Note that the mode signal S0 in fig. 2 represents the first to third mode signals. That is, the mode control device 280 can output any one of the first to third mode signals according to the comparison result, and for the convenience of simple description in the present invention, the mode signal S0 is used as a representative signal. The control device 290 is coupled to the Mode control device 280 and the first to fourth switches 222 to 264, and outputs first to fourth control signals S1 to S4 according to the Mode signal S0 to control the first to fourth switches 222 to 264 to perform an alternating operation of turning on and off, and to turn on or off completely, respectively, so that the multi-Mode power converter 200 can operate in a direct-pass Mode (By-pass Mode), a Buck Mode (Buck Mode) or a Boost Mode (Boost Mode) according to the switch states. An important feature of the present invention is the through mode of the multi-mode power converter 200, in which the first switch 222 and the third switch 262 are fully turned on, and the second switch 224 and the fourth switch 264 are fully turned off.

In some embodiments of the present invention, the first to fourth switches (222, 224, 262, 264) are capable of withstanding high voltage and flowing large current, and power transistors may be used, for example, the first switch 222 and the third switch 262 are power PMOS transistors, and the second switch 224 and the fourth switch 264 are power NMOS transistors. The invention is not so limited. In addition, a parasitic diode exists between the source and the drain of the MOS transistor, or the MOS transistor is designed with a diode. This design is advantageous in that when the first switch 222 or the third switch 262 needs to be turned on, only a low voltage (or zero voltage) is applied to the gate terminal of the PMOS transistor. The multi-mode power converter 200 is designed without additional high voltage circuits for the first switch 222 and the third switch 262. Compared with the traditional design, the design of the invention is simpler and the cost is reduced.

As described above, when the mode control device 280 detects that the input voltage is lower than the second voltage Vref2, the mode control device 280 outputs the third mode signal to the control device 290, so that the multi-mode power converter 200 operates in the boost mode. When the mode control device 280 detects that the input voltage is higher than the first voltage Vref1, the mode control device 280 outputs a second mode signal to the driving control device 290, so that the multi-mode power converter 200 operates in the buck mode. When the mode control device 280 detects that the input voltage Vin is between the second voltage Vref2 and the first voltage Vref1, the mode control device 280 outputs a first mode signal to the control device 290, so that the multi-mode power converter 200 operates in the through mode. To summarize, when the input voltage Vin is greater than the first voltage value Vref1, the mode control device 280 outputs the second mode signal such that the multi-mode power converter performs the buck mode. When the input voltage Vin is less than the second voltage value Vref2, the mode control device 280 outputs a third mode signal to cause the multi-mode power converter to perform the boost mode. When the input voltage Vin is not greater than the first voltage value Vref and not less than the second voltage value Vref2, the mode control device 280 outputs a first mode signal such that the multi-mode power converter performs a pass-through mode.

In some embodiments of the present invention, when the power converter 200 operates in the through mode, the control device 290 outputs the control signals S1 to S4 to make the first switch 222 fully turned on and the second switch 224 fully turned off (turned off); and the third switch 262 is fully on and the fourth switch 264 is fully off. In the through mode, since the first switch 222 is turned on and the third switch 262 is fully turned on, the input voltage Vin from the dc voltage source 500 may be through to the output node N, so the input voltage Vin is equal to the output voltage Vout, and the load 600 may receive the output voltage Vout through the third switch 262. That is, when the input voltage Vin is between or equal to the second voltage Vref2 and the first voltage Vref1, the input voltage Vin is equal to the output voltage Vout.

When the multi-mode power converter 200 operates in the pass-through mode, no switch in the multi-mode power converter 200 alternates between on and off states because the first switch 222 is turned on and the third switch 262 is maintained in an on state and the second switch 224 is turned on and the fourth switch 264 is maintained in an off state. Due to the design, the multi-mode power converter 200 does not have the switching loss and the mode switching loss of the conventional power converter under the condition that the multi-mode power converter 200 operates in the through mode, so that the working efficiency of the power converter 200 is greatly improved.

In some embodiments of the present invention, when the comparing device 282 in the mode control device 280 identifies that the input voltage Vin is greater than the first voltage Vref1, the power converter 200 operates in the buck mode. The comparator 282 of the mode control device 280 outputs a second mode signal, and the control device 290 outputs the first to fourth control signals S1-S4 according to the second mode signal, so that the first switch 222 and the second switch 224 are alternately turned on and off; and the third switch 262 is fully on and the fourth switch 264 is fully off. The alternating operation of the first switch 222 and the second switch 224 can switch the input voltage Vin and charge and discharge the energy storage element 240. The third switch 262 rectifies the voltage from the rectifying element 240 to form the output voltage Vout. The load 600 receives the output voltage Vout through the third switch 262 to maintain power required for operation. It is particularly noted that the first switch 222 and the second switch 224 perform the alternating operations of turning on and off: when the first switch 222 is turned on, the second switch 224 is turned off; when the second switch 224 is turned on, the first switch 222 is turned off.

In some embodiments of the present invention, when the comparing device 282 in the mode control device 280 identifies that the input voltage Vin is lower than the second voltage Vref2, the power converter 200 operates in the boost mode. The comparator 282 of the mode controller 280 outputs a third mode signal according to the comparison result, and the first to fourth control signals S1-S4 outputted by the controller 290 make the first switch 222 be completely turned on and the second switch 224 be completely turned off; and the third switch 262 is completely turned off (at this time, the third switch 262 is operated as a synchronous rectification mode as a whole) and the fourth switch 264 is turned on and turned off alternately, wherein the third switch 262 is a mosfet having a parasitic diode 262a (parasitic diode), but the invention is not limited thereto, so that the third switch 262 is synchronously rectified by the diode 262a at this time (when turned off). The input voltage Vin charges the energy storage element 240 through the first switch 222. The fourth switch 264 switches the dc voltage from the energy storage element 240 and transmits the dc voltage to the third switch 262 to generate the output voltage Vout. The load 600 receives the output voltage Vout through the third switch 262 to maintain power required for operation. It is noted that when the third switch 262 is turned off, the dc voltage can still be transmitted to the output node N through the parasitic diode 262a, and the parasitic diode 262a has a function of rectifying the voltage and the current. Therefore, in this embodiment, the third switch 262 operates in the synchronous rectification mode.

Fig. 3 is a circuit diagram of a multi-mode power converter 200 according to some other embodiments of the invention. Referring to fig. 2 and 3, the main function of the third switch 262 in fig. 2 is to keep conducting and rectify the voltage from the energy storage device 240, so in other embodiments, the third switch 262 can be replaced by other rectification devices. In this example, the third switch 262 is replaced with a rectifying diode 266, but the invention is not limited thereto. In addition to rectifying the dc voltage from the energy storage device, the rectifying diode 266 can also prevent reverse current generated by the load 600 from flowing back to other components or elements in the multi-mode power converter 200. In this example, the operation method and principle of the multi-mode power converter 200 are the same as those in fig. 2, and therefore, the description thereof is omitted.

As shown in the embodiment of fig. 3, the circuit design of the multi-mode power converter 200 is simplified due to the reduced number of switches, and the number of switches required to be controlled by the control device 290 is reduced, thereby reducing the loss of the control device 290. The design further reduces the production cost of the product, and the product is more competitive in the market.

Fig. 4 is a waveform diagram of a multi-mode power converter according to an embodiment of the invention. Referring to fig. 2 and 4, in the initial stage of the multi-mode power converter 200, if the input voltage Vin from the dc voltage source 500 is greater than the first voltage Vref1 of the multi-mode power converter, the multi-mode power converter 200 starts to operate in the buck mode to convert the input voltage Vin to the same output voltage Vout as the first voltage Vref 1. If the input voltage Vin is always greater than the first voltage Vref1, the multi-mode power converter 200 continues to operate in the buck mode.

In fig. 2 and 4, when the input voltage Vin decreases to the first voltage Vref1, the power converter 200 will stop the buck mode and convert to the through mode. In the through mode, the input voltage Vin is equal to the output voltage Vout of the power converter 200 because the multi-mode power converter 200 passes the input voltage Vin directly to the output terminal. It is noted that if the magnitude of the input voltage Vin is maintained between the first voltage Vref1 and the second voltage Vref2, the multi-mode power converter 200 will continue to perform the pass-through mode until the input voltage Vin is less than the second voltage Vref2 or greater than the first voltage Vref 1.

Referring to fig. 2 and 4, if the input voltage Vin is less than the second voltage Vref2, the multi-mode power converter 200 of the power converter 200 performs the boost mode to convert the input voltage Vin into the output voltage Vout equal to the second voltage Vref 2. When the dc input voltage is less than the second voltage Vref2, the multi-mode power converter 200 will continue the boost mode until the input voltage Vin is greater than the second voltage Vref 2.

Fig. 5 illustrates waveforms for a multi-mode power converter according to some other embodiments of the present invention. Referring to fig. 2 and 5, if the input voltage Vin generated by the dc voltage source 500 is less than the second voltage Vref2 of the multi-mode power converter 200 during the initial operation of the multi-mode power converter 200, the multi-mode power converter 200 starts to operate in the boost mode. At this time, the multi-mode power converter 200 converts the input voltage Vin into the output voltage Vout having the same value as the second voltage Vref2, and maintains a stable dc output voltage. When the input voltage Vin is less than the second voltage Vref2, the multi-mode power converter 200 will continue in the boost mode until the input voltage Vin equals the second voltage Vref2, and the multi-mode power converter 200 stops the boost mode.

Referring to fig. 2 and 5, when the input voltage Vin rises to the second voltage Vref2 over time, the multi-mode power converter 200 stops the boost mode and starts to perform the pass-through mode. In the through mode, the input voltage Vin is equal to the output voltage Vout. If the magnitude of the input voltage Vin is maintained between the second voltage Vref2 and the first voltage Vref1, the multi-mode power converter 200 will continue to operate in the pass mode. If the input voltage Vin is greater than the first voltage Vref1 or less than the second voltage Vref2, the multi-mode power converter 200 leaves the through mode.

In some other embodiments, if the input voltage Vin is greater than the first voltage Vref1, the multi-mode power converter performs the step-down mode to convert the input voltage Vin to the output voltage Vout equal to the first voltage Vref 1. When the input voltage Vin is greater than the first voltage Vref1, the multi-mode power converter 200 will continue to operate in the buck mode.

In fig. 4 and 5, the first Voltage Vref1 and the second Voltage Vref2 can be regarded as a Voltage gate threshold (voltagetehreshold) or a Reference Voltage (Reference Voltage). The second voltage Vref2 and the first voltage Vref1 can be set differently according to the input specification of the load 600 or the upper and lower limits of the Duty ratio (Duty) of the PWM signal, which can be easily understood by those skilled in the art and can be easily modified to achieve the object of the present invention. The disclosure is only exemplary of the first voltage Vref1 and the second voltage Vref2, and is not intended to limit the present invention.

As can be seen from fig. 2, 4, and 5, even when the input voltage Vin varies widely with time, the output voltage Vout of the multi-mode power converter 200 can be stably maintained between the lower and upper voltage limits Vref1 and Vref 2. Although the design of the present invention causes the disadvantage of the variation of the output voltage Vout between the upper buck limit Vref1 and the lower boost limit Vref2, the slight variation of the output voltage can still meet the power requirement for maintaining stable operation of most electronic products in the market, for example: electronic computers, notebook computers, tablet computers, smart phones, smart watches, mobile power supplies, and the like. The steps of the design method of the present invention will be described in detail below to achieve the object of the present invention.

Fig. 6 illustrates a method 300 step diagram of a multi-mode power converter according to some embodiments of the invention. The flow of the method 300 is described below with reference to fig. 2. In the method 300, beginning with step 310, after receiving the input voltage Vin via the mode control device 280, the multi-mode power converter 200 proceeds to step 315. In FIG. 2, the reference voltage circuit 284 in the mode control device 280 sets a first voltage Vref1 and a second voltage Vref 2. Therefore, when the multi-mode power converter 200 performs step 315, the mode control device 280 compares the input voltage Vin with the first voltage Vref1 and the second voltage Vref2, and the comparison result can be step 320, step 340 or step 360, and the multi-mode power converter 200 proceeds to step 322, step 342 or step 362 according to the comparison result.

When the mode control device 280 recognizes that the input voltage Vin is between the first voltage Vref1 and the second voltage Vref2, the multi-mode power converter 200 proceeds to step 322 where the mode control device 280 outputs a first mode signal to the control device 290 and proceeds to step 322. In step 322, the control device 290 then outputs the first to fourth control signals S1-S4 to the first switch 222, the second switch 224, the third switch 262 and the fourth switch 264 and proceeds to step 326. In step 326, the multi-mode power converter 200 performs a pass-through mode.

When the mode control device 280 recognizes that the input voltage Vin is greater than the first voltage Vref1, the multi-mode power converter 200 executes step 342 and the mode control device 280 outputs the second mode signal to the control device 290. in step 344, the control device 290 then outputs the first to fourth control signals S1 to S4 to change the operation states of the first switch 222, the second switch 224, the third switch 262 and the fourth switch 264 and proceeds to step 346. After the multi-mode power converter 200 performs step 346, the multi-mode power converter 200 performs the buck mode.

When the mode control means 280 recognizes that the input voltage Vin is less than the second voltage Vref2, the multi-mode power converter 200 executes step 362 such that the mode control means 280 outputs a third mode signal to the control means 290. In step 364, the control device 290 then outputs the first to fourth control signals S1-S4 to the first switch 222, the second switch 224, the third switch 262 and the fourth switch 264, and the switches perform different operation states according to the first to fourth control signals S1-S4 and enter step 366. In step 366, the multi-mode power converter 200 executes a boost mode.

In various embodiments of the present invention, the multi-mode power converter 200 proceeds to step 310 and step 315 at the same time, regardless of whether

step

326, 346 or 366 is performed. That is, the mode control device 280 continuously receives the input voltage Vin and compares the input voltage Vin with the first voltage Vref1 and the second voltage Vref 2. When there is any change in the input voltage Vin, the multi-mode power converter can be switched among a through mode, a buck mode and a boost mode to maintain a stable output voltage Vout.

In some embodiments of the present invention, the multi-mode power converter 200 in fig. 2 to 5 may set one or more than two reference voltages according to actual requirements. In fig. 4 and 5, in order to simply illustrate the operation principle of the multi-mode power converter operating in the through mode, the first voltage Vref1 and the second voltage Vref2 are provided as examples, but the disclosure is not limited thereto.

In summary, the through mode of the multi-mode power converter operates between the first voltage Vref1 and the second voltage Vref2, and the input voltage is equal to the output voltage. Although the multi-mode power converter designed in this way has the defect of slightly varying the output voltage, the output voltage variation is allowable by the electronic products on the market. However, the greatest advantage of such a design is that the operating efficiency of the multi-mode power converter is significantly improved and the switching loss of the switch is reduced when the input voltage is close to the output voltage.

Although the present invention has been described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, to the extent that the terms "includes," including, "" has, "or other variants thereof are used in either the detailed description and/or the claims, such terms are intended to have the same meaning as the term" comprising.

Claims

1. A multi-mode power converter comprising:

an energy storage element having a first end and a second end;

a first switch coupled to an input voltage and the first terminal;

a second switch coupled to the first terminal and a reference node;

a third switch coupled to the second terminal and an output node;

a fourth switch coupled to the second terminal and the reference node;

a mode control device, coupled to the input voltage, for determining a voltage range of the input voltage according to a first voltage and a second voltage, the mode control device outputting a first mode signal, a second mode signal, and a third mode signal respectively corresponding to a direct mode, a buck mode, and a boost mode according to the determination result, the first voltage being greater than a rated output voltage of the multi-mode power converter, the second voltage being less than the rated output voltage; and

a control device coupled to the mode control device and the first switch, the second switch, the third switch, and the fourth switch, and outputting a first control signal, a second control signal, a third control signal, and a fourth control signal according to the first mode signal, the second mode signal, and the third mode signal, so as to control the first switch, the second switch, the third switch, and the fourth switch to be turned on/off alternatively or completely, so that the multi-mode power converter operates in the pass-through mode, the buck mode, or the boost mode, respectively;

in the through mode, the first switch and the third switch are completely turned on, and the second switch and the fourth switch are completely turned off.

2. The multi-mode power converter of claim 1, wherein the mode control device outputs the second mode signal when the input voltage is greater than the first voltage, the third mode signal when the input voltage is less than the second voltage, and the first mode signal when the input voltage is not greater than the first voltage and not less than the second voltage.

3. The multi-mode power converter as claimed in claim 2, wherein when the multi-mode power converter operates in the buck mode, the control device outputs the first control signal, the second control signal, the third control signal, and a fourth control signal according to the second mode signal, such that the first switch and the second switch are alternately turned on and off, the third switch is fully turned on, and the fourth switch is fully turned off.

4. The multi-mode power converter as claimed in claim 2, wherein when the multi-mode power converter operates in the boost mode, the control device outputs the first control signal, the second control signal, the third control signal, and the fourth control signal according to the third mode signal, such that the first switch is fully turned on, the second switch is fully turned off, the third switch is fully turned off, and the fourth switch performs an alternating operation of turning on and off, wherein the third switch is a mosfet having a diode through which the third switch operates in a synchronous rectification mode.

5. The multi-mode power converter of claim 1, wherein the first switch and the third switch are pass devices of a P-type metal oxide semiconductor field effect transistor.

6. The multi-mode power converter of claim 1, wherein the second switch and the fourth switch are pass devices of an N-type metal oxide semiconductor field effect transistor.

7. A multi-mode power converter comprising:

an energy storage element having a first end and a second end;

a first switch coupled to an input voltage and the first terminal;

a second switch coupled to the first terminal and a reference node;

a third switch coupled to the second terminal and the reference node;

a rectifying diode coupled to the second terminal and an output node;

a control device coupled to the mode control device and the first switch, the second switch, and the third switch, and outputting a first control signal, a second control signal, and a third control signal according to the first mode signal, the second mode signal, and the third mode signal, so as to control the first switch, the second switch, and the third switch to conduct or close completely alternately, so that the multi-mode power converter operates in the pass-through mode, the buck mode, or the boost mode;

in the through mode, the first switch is fully turned on, and the second switch and the third switch are fully turned off.