Bidirectional voltage conversion circuit suitable for high power

Abstract

A bidirectional voltage conversion circuit is disclosed, which includes a first switch coupled between an input terminal and a first switch terminal, a second switch coupled between the first switch terminal and a reference ground terminal, a first inductor coupled between the first switch terminal and an output switch terminal, a third switch coupled between the output switch terminal and a system terminal, a fourth switch coupled between the output switch terminal and a reference ground terminal, and a fifth switch connected in parallel to both ends of the third switch. The bidirectional voltage conversion circuit can operate in a buck charging mode to convert an input voltage at an input terminal into a buck charging voltage at a system terminal, or in a boost discharge mode to convert a system voltage at a system terminal into a boost discharge voltage at an input terminal. When the bidirectional voltage conversion circuit operates in the buck charging mode or the boost discharge mode, in each switching cycle, the first switch and the second switch are complementarily turned on and off, the third switch and the fifth switch remain turned on, and the fourth switch remains turned off.

Description

Technical Field

[0001] The invention relates to a bidirectional voltage conversion circuit, in particular to a large current and high power bidirectional voltage conversion circuit. Background Art

[0002] Bidirectional voltage conversion circuits are widely used in battery management systems because they can charge the battery when the power is supplied, and when the power is off, the battery supplies power to other circuits of the system through the bidirectional voltage conversion circuit. As the charging protocol continues to improve the charging speed, the power handled by the bidirectional voltage conversion circuit is getting larger and larger. In actual applications, in order to save chip costs, the chip size of the two-wire voltage conversion circuit is as small as possible, so some high-power applications often do not meet the application requirements due to poor temperature characteristics (overheating). Therefore, in high-power applications, it is hoped that the efficiency of the bidirectional voltage conversion circuit can be further improved. At present, when the bidirectional voltage conversion circuit handles high power, it is usually necessary to redesign the bidirectional voltage conversion circuit based on efficiency indicators.

[0003] Therefore, a bidirectional voltage conversion circuit is needed, which can be suitable for low-power applications and can further improve efficiency in high-power applications. Summary of the invention

[0004] An embodiment of the present invention provides a bidirectional voltage conversion circuit, the bidirectional voltage conversion circuit is coupled between an input terminal and a system terminal, the bidirectional voltage conversion circuit includes a first switch, a second switch, and a first inductor, wherein the first switch is coupled between the input terminal and the first switch terminal, the second switch is coupled between the first switch terminal and a reference ground terminal, the first inductor is coupled between the first switch terminal and an output switch terminal, the third switch is coupled between the output switch terminal and the system terminal, the fourth switch is coupled between the output switch terminal and the reference ground terminal, and the fifth switch is connected in parallel to both ends of the third switch, the bidirectional voltage conversion circuit can work in a buck charging mode to connect the input terminal to the system terminal. The received input voltage is converted into a buck charging voltage at the system end, or the boost discharge mode converts the system voltage at the system end into a boost discharge voltage at the input end, wherein when the bidirectional voltage conversion circuit operates in the buck charging mode, in each switching cycle, the first switch and the second switch are complementarily turned on and off, the third switch and the fifth switch remain turned on, and the fourth switch remains turned off; when the bidirectional voltage conversion circuit operates in the boost discharge mode, in each switching cycle, the first switch and the second switch are complementarily turned on and off, the third switch and the fifth switch remain turned on, and the fourth switch remains turned off, wherein the buck charging voltage is less than the input voltage, and the boost discharge voltage is greater than the system voltage.

[0005] According to the bidirectional voltage conversion circuit provided by the present invention, when it operates in the step-down charging mode or the step-up discharging mode, the fifth switch remains turned on, thereby improving the working efficiency of the bidirectional voltage conversion circuit and having better temperature characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In order to better understand the present invention, embodiments of the present invention will be described according to the following drawings, which are only for example. The drawings generally only show some features of the embodiments, and the drawings are not necessarily drawn to scale.

[0007] Figure 1 A circuit diagram of a bidirectional voltage conversion circuit 100 according to an embodiment of the present invention is provided.

[0008] Figure 2 A circuit diagram of a bidirectional voltage conversion circuit 200 according to another embodiment of the present invention is provided.

[0009] Figure 3 The waveform diagram of each control signal when the bidirectional voltage conversion circuit 200 according to an embodiment of the present invention works in the boost charging mode is given.

[0010] Figure 4 The waveform diagram of each control signal when the bidirectional voltage conversion circuit 200 according to an embodiment of the present invention works in the buck charging mode is given.

[0011] Figure 5 The waveform diagram of each control signal when the bidirectional voltage conversion circuit 200 according to an embodiment of the present invention works in the boost discharge mode is given.

[0012] Figure 6 The waveform diagram of each control signal when the bidirectional voltage conversion circuit 200 according to an embodiment of the present invention works in the step-down discharge mode is given.

[0013] The same reference numbers in different schematic drawings indicate the same or similar parts or features. DETAILED DESCRIPTION

[0014] Specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is apparent to those of ordinary skill in the art that these specific details need not be adopted to implement the present invention. In other embodiments, in order to avoid confusing the present invention, known circuits, materials or methods are not specifically described.

[0015] In the specification and claims of the present disclosure, if words such as "left, right, inside, outside, up, down, above, below" are used, they are only for the convenience of description and do not indicate the necessary or permanent relative position of the components / structures. Those skilled in the art should understand that such words are interchangeable under appropriate circumstances, for example, so that the embodiments of the present disclosure can still operate in directions different from those described in the present specification. In the context of the present disclosure, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intermediate layer / element between them. In addition, the term "coupled" means connected in a direct or indirect electrical or non-electrical manner. "One / this / that" is not used to specifically refer to the singular, but may cover the plural form. The phrases "one embodiment", "embodiment", "an example", and "example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Those of ordinary skill in the art should understand that the various specific features, structures or parameters, steps, etc. disclosed in one or more embodiments of the present disclosure can be combined in any appropriate manner. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0016] Figure 1A circuit diagram of a bidirectional voltage conversion circuit 100 according to an embodiment of the present invention is given. The bidirectional voltage conversion circuit 100 is coupled between an input terminal IN and a system terminal SYS, and can work in a charging mode, that is, converting an input voltage VIN of the input terminal IN into a system voltage VSYS of the system terminal SYS, and can also work in a discharging mode, that is, converting the voltage of the system terminal SYS into a voltage required by the input terminal IN. The bidirectional voltage conversion circuit 100 includes a first switch Q1, a second switch Q2, a first inductor L1, a third switch Q3, a fourth switch Q4, and a fifth switch Q5. The first switch Q1 is coupled between the input terminal IN and the first switch terminal SWA, the second switch Q2 is coupled between the first switch terminal SWA and the reference ground terminal GND, the first inductor L1 is coupled between the first switch terminal SWA and the output switch terminal SWB, the third switch Q3 is coupled between the output switch terminal SWB and the system terminal SYS, the fourth switch Q4 is coupled between the output switch terminal SWB and the reference ground terminal GND, and the fifth switch Q5 is connected in parallel to both ends of the third switch Q3. In one embodiment, the first switch Q1, the second switch Q2, the third switch Q3 and the fourth switch Q4 are integrated on a semiconductor chip, and the fifth switch Q5 is external. The bidirectional voltage conversion circuit 100 also includes a mode switching circuit and a switch control circuit, wherein the mode switching circuit is used to provide a boost charging enable signal M1, a buck charging enable signal M2, a boost discharge enable signal M3 and a buck discharge enable signal M4 to control the bidirectional voltage conversion circuit 100 to work in a boost charging mode, a buck charging mode, a boost discharge mode or a buck discharge mode, respectively. When the boost charging enable signal M1 is in a first state, the bidirectional voltage conversion circuit 100 works in a boost charging mode, when the buck charging enable signal M2 is in a first state, the bidirectional voltage conversion circuit 100 works in a buck charging mode, when the boost discharge enable signal M3 is in a first state, the bidirectional voltage conversion circuit 100 works in a boost discharge mode, and when the buck discharge enable signal M4 is in a first state, the bidirectional voltage conversion circuit 100 works in a buck discharge mode. In one embodiment, the mode switching circuit receives instructions through the I2C interface to set the boost charge enable signal M1, the buck charge enable signal M2, the boost discharge enable signal M3, and the buck discharge enable signal M4. In another embodiment, the mode switching circuit sets the boost charge enable signal M1, the buck charge enable signal M2, the boost discharge enable signal M3, and the buck discharge enable signal M4 by detecting the voltage of the input terminal IN and the voltage of the system terminal SYS.The switch control circuit generates a first control signal PWMA to control the on and off of the first switch Q1 and the second switch Q2, a second control signal PWMB to control the on and off of the third switch Q3 and the fourth switch Q4, and a gate drive signal CTRL to control the on and off of the fifth switch Q5 according to the received boost charge enable signal M1, buck charge enable signal M2, boost discharge enable signal M3 and buck discharge enable signal M4. Figure 1 In the embodiment, the bidirectional voltage conversion circuit 100 further includes an input capacitor CIN coupled to the input terminal IN, and a load capacitor CO coupled to the system terminal SYS.

[0017] When the bidirectional voltage conversion circuit 100 operates in the boost charging mode, in each switching cycle, the first switch Q1 remains turned on, the second switch Q2 remains turned off, the third switch Q3 and the fourth switch Q4 are turned on and off complementarily, and the fifth switch Q5 remains turned off. The bidirectional voltage conversion circuit 100 converts the input voltage VIN received by the input terminal IN into a boost charging voltage VCT of the system terminal SYS, and the boost charging voltage VCT is greater than the input voltage VIN. The third switch Q3 and the fourth switch Q4 are turned on and off complementarily, which means that in one switching cycle, when the third switch Q3 is in the on state, the fourth switch Q4 is in the off state, and when the third switch Q3 is in the off state, the fourth switch Q4 is in the on state. When the bidirectional voltage conversion circuit 100 operates in the buck charging mode, in each switching cycle, the first switch Q1 and the second switch Q2 are turned on and off complementarily, the third switch Q3 and the fifth switch Q5 remain turned on, and the fourth switch Q4 remains turned off. The bidirectional voltage conversion circuit 100 converts the input voltage VIN received by the input terminal IN into a buck charging voltage VCK of the system terminal SYS, and the buck charging voltage VCK is less than the input voltage VIN. The first switch Q1 and the second switch Q2 are turned on and off complementarily, which means that in one switching cycle, when the first switch Q1 is in the on state, the second switch Q2 is in the off state, and when the first switch Q1 is in the off state, the second switch Q2 is in the on state. When the bidirectional voltage conversion circuit 100 operates in the buck charging mode, the ratio of the duration of the first switch Q1 being turned on to the switching cycle is defined as the buck duty cycle DBK, and the buck duty cycle DBK is determined by the input voltage VIN and the buck charging voltage VCK. In one embodiment, when the input voltage VIN is constant, the higher the buck charging voltage VCK is, the larger the buck duty cycle DBK is. In another embodiment, when the buck charging voltage VCK is constant, the higher the input voltage VIN is, the smaller the buck duty cycle DBK is.

[0018] When the bidirectional voltage conversion circuit 100 operates in the boost discharge mode, in each switching cycle, the first switch Q1 and the second switch Q2 are complementarily turned on and off, the third switch Q3 and the fifth switch Q5 remain turned on, and the fourth switch Q4 remains turned off. The bidirectional voltage conversion circuit 100 converts the system voltage VSYS of the system terminal SYS into the boost discharge voltage VDT of the input terminal IN, and the boost discharge voltage VDT is greater than the system voltage VSYS. When the bidirectional voltage conversion circuit 100 operates in the boost discharge mode, the ratio of the duration of the first switch Q1 being turned on to the switching cycle is defined as the boost duty cycle DBT, and the boost duty cycle DBT of the first switch Q1 is determined by the system voltage VSYS and the boost discharge voltage VDT. In one embodiment, when the system voltage VSYS is constant, the higher the boost discharge voltage VDT is, the greater the boost duty cycle DBT is. In another embodiment, when the boost discharge voltage VDT is constant, the higher the system voltage VSYS is, the smaller the boost duty cycle DBT is. When the bidirectional voltage conversion circuit 100 operates in the buck discharge mode, in each switching cycle, the first switch Q1 remains turned on, the second switch Q2 remains turned off, the third switch Q3 and the fourth switch Q4 are turned on and off complementarily, and the fifth switch Q5 remains turned off. The bidirectional voltage conversion circuit 100 converts the system voltage VSYS of the system terminal SYS into a buck discharge voltage VDK of the input terminal IN, wherein the buck discharge voltage VDK is less than the system voltage VSYS.

[0019] Figure 2A circuit diagram of a bidirectional voltage conversion circuit 200 according to another embodiment of the present invention is given. Compared with the bidirectional voltage conversion circuit 100, the bidirectional voltage conversion circuit 200 further includes a second inductor L2, a sixth switch Q6 and a seventh switch Q7. The sixth switch Q6 is coupled between the input terminal IN and the second switch terminal SWC, the seventh switch Q7 is coupled between the second switch terminal SWC and the reference ground terminal GND, the second inductor L2 is coupled between the second switch terminal SWC and the reference ground terminal GND, and the sixth switch Q6 and the seventh switch Q7 are turned on and off under the control of the third control signal PWMC. The bidirectional voltage conversion circuit 200 can operate in a boost charging mode, a buck charging mode, a boost discharge mode or a buck discharge mode under the control of the boost charging enable signal M1, the buck charging enable signal M2, the boost discharge enable signal M3 and the buck discharge enable signal M4. When the bidirectional voltage conversion circuit 200 operates in the boost charging mode, in each switching cycle, the first switch Q1 remains on, the second switch Q2 remains off, the third switch Q3 and the fourth switch Q4 are complementarily turned on and off, the fifth switch Q5 remains off, the sixth switch Q6 remains on, and the seventh switch Q7 remains off. When the bidirectional voltage conversion circuit 200 operates in the buck charging mode, in each switching cycle, the first switch Q1 and the second switch Q2 are complementarily turned on and off, the third switch Q3 and the fifth switch Q5 remain on, the fourth switch Q4 remains off, and the sixth switch Q6 and the seventh switch Q7 are complementarily turned on and off. The complementarily turned on and off of the sixth switch Q6 and the seventh switch Q7 means that in one switching cycle, when the sixth switch Q6 is in the on state, the seventh switch Q7 is in the off state, and when the sixth switch Q6 is in the off state, the seventh switch Q7 is in the on state. In one embodiment, the first switch Q1 and the sixth switch Q6 are turned on and off synchronously, that is, the first switch Q1 and the sixth switch Q6 are turned on at the same time. When the bidirectional voltage conversion circuit 200 operates in the boost discharge mode, in each switching cycle, the first switch Q1 and the second switch Q2 are turned on and off complementarily, the third switch Q3 and the fifth switch Q5 remain turned on, the fourth switch Q4 remains turned off, and the sixth switch Q6 and the seventh switch Q7 are turned on and off complementarily. In one embodiment, in each switching cycle, the first switch Q1 and the sixth switch Q6 are turned on and off synchronously, that is, the first switch Q1 and the sixth switch Q6 are turned on at the same time. When the bidirectional voltage conversion circuit 200 operates in the buck discharge mode, in each switching cycle, the first switch Q1 and the sixth switch Q6 remain turned on, the second switch Q2 and the seventh switch Q7 remain turned off, the third switch Q3 and the fourth switch Q4 are turned on and off complementarily, and the fifth switch Q5 remains turned off.

[0020] Figure 3 The waveform diagram of each control signal when the bidirectional voltage conversion circuit 200 according to an embodiment of the present invention works in the boost charging mode is given. Figure 3 As shown, from top to bottom are the first control signal PWMA, the second control signal PWMB, the gate drive signal CTRL and the third control signal PWMC. When the bidirectional voltage conversion circuit 200 operates in the boost charging mode, in each switching cycle T, the first control signal PWMA is in a logic high state to control the first switch Q1 to remain on and the second switch Q2 to remain off. When the second control signal PWMB is in a logic high state, the third switch Q3 is turned on and the fourth switch Q4 is turned off. When the second control signal PWMB is in a logic low state, the third switch Q3 is turned off and the fourth switch Q4 is turned on. The gate drive signal CTRL is in a logic high state to control the fifth switch Q5 to remain on. The third control signal PWMC is in a logic high state to control the sixth switch Q6 to remain on and the seventh switch Q7 to remain off.

[0021] Figure 4 The waveform diagram of each control signal when the bidirectional voltage conversion circuit 200 according to an embodiment of the present invention works in the buck charging mode is given. Figure 4 As shown, from top to bottom are the first control signal PWMA, the second control signal PWMB, the gate drive signal CTRL and the third control signal PWMC. When the bidirectional voltage conversion circuit 200 operates in the buck charging mode, within each switching cycle T, when the first control signal PWMA is in a logic high state, the first switch Q1 is turned on and the second switch Q2 is turned off; when the first control signal PWMA is in a logic low state, the first switch Q1 is turned off and the second switch Q2 is turned on. The second control signal PWMB is in a logic high state to control the third switch Q3 to remain turned on and the fourth switch Q4 to remain turned off. The gate drive signal CTRL is in a logic high state to control the fifth switch Q5 to remain turned on. When the third control signal PWMC is in a logic high state, the sixth switch Q6 is turned on and the seventh switch Q7 is turned off; when the third control signal PWMC is in a logic low state, the sixth switch Q6 is turned off and the seventh switch Q7 is turned on. Figure 4 In the embodiment shown, the phase difference between the third control signal PWMC and the first control signal PWMA is 180°. In other embodiments, the phase difference between the third control signal PWMC and the first control signal PWMA may be zero, that is, the first switch Q1 and the sixth switch Q6 are turned on at the same time. Figure 4 In the embodiment, the ratio of the duration that the first control signal PWMA is in the logic high state to the switching period T is the buck duty cycle DBK.

[0022] Figure 5 The waveform diagram of each control signal when the bidirectional voltage conversion circuit 200 according to an embodiment of the present invention works in the boost discharge mode is given. Figure 5As shown, from top to bottom are the first control signal PWMA, the second control signal PWMB, the gate drive signal CTRL and the third control signal PWMC. When the bidirectional voltage conversion circuit 200 operates in the boost discharge mode, within each switching period T, when the first control signal PWMA is in a logic high state, the first switch Q1 is turned on and the second switch Q2 is turned off; when the first control signal PWMA is in a logic low state, the first switch Q1 is turned off and the second switch Q2 is turned on. The second control signal PWMB is in a logic high state to control the third switch Q3 to remain turned on and the fourth switch Q4 to remain turned off. The gate drive signal CTRL is in a logic high state to control the fifth switch Q5 to remain turned on. When the third control signal PWMC is in a logic high state, the sixth switch Q6 is turned on and the seventh switch Q7 is turned off; when the third control signal PWMC is in a logic low state, the sixth switch Q6 is turned off and the seventh switch Q7 is turned on. Figure 5 In the embodiment shown, the phase difference between the third control signal PWMC and the first control signal PWMA is 180°. In other embodiments, the phase difference between the third control signal PWMC and the first control signal PWMA may be zero, that is, the first switch Q1 and the sixth switch Q6 are turned on at the same time. Figure 5 In the embodiment, the ratio of the duration of the first control signal PWMA being in the logic high state to the switching period T is the boost duty cycle DBT.

[0023] Figure 6 The waveform diagram of each control signal when the bidirectional voltage conversion circuit 200 according to an embodiment of the present invention works in the step-down discharge mode is given. Figure 6 As shown, from top to bottom are the first control signal PWMA, the second control signal PWMB, the gate drive signal CTRL and the third control signal PWMC. When the bidirectional voltage conversion circuit 200 operates in the buck discharge mode, in each switching cycle T, the first control signal PWMA is in a logic high state to control the first switch Q1 to remain on and the second switch Q2 to remain off. When the second control signal PWMB is in a logic high state, the third switch Q3 is turned on and the fourth switch Q4 is turned off. When the second control signal PWMB is in a logic low state, the third switch Q3 is turned off and the fourth switch Q4 is turned on. The gate drive signal CTRL is in a logic low state to control the fifth switch Q5 to remain off. The third control signal PWMC is in a logic high state to control the sixth switch Q6 to remain on and the seventh switch Q7 to remain off.

[0024] When the bidirectional voltage conversion circuit of the present invention is used and operates in a step-down charging mode or a step-up discharging mode, the fifth switch Q5 remains turned on, thereby improving the working efficiency of the bidirectional voltage conversion circuit and having better temperature characteristics.

[0025] The above-mentioned specific embodiments are only used to illustrate the high pressure period and the manufacturing method of the embodiment of the present invention in an exemplary manner. These embodiments are not completely exhaustive and are not intended to limit the scope of the present invention. It is possible to change and modify the disclosed embodiments, and other feasible optional embodiments and equivalent changes to the elements in the embodiments can be understood by ordinary technicians in this technical field. Other changes and modifications of the embodiments disclosed by the present invention do not exceed the spirit of the present invention and the scope of protection defined by the claims.

Claims

1. A bidirectional voltage conversion circuit, coupled between an input terminal and a system terminal, the bidirectional voltage conversion circuit comprising: A first switch, coupled between the input terminal and the first switch terminal; A second switch, coupled between the first switch terminal and a reference ground terminal; A first inductor coupled between the first switch terminal and the output switch terminal; A third switch coupled between the output switch terminal and the system terminal; a fourth switch coupled between the output switch terminal and the reference ground terminal; a fifth switch connected in parallel to two ends of the third switch; A second inductor is coupled between the second switch terminal and the output switch terminal; A sixth switch, coupled between the input terminal and the second switch terminal; as well as a seventh switch, coupled between the second switch terminal and the reference ground terminal; In which, the bidirectional voltage conversion circuit can operate in a buck charging mode to convert the input voltage received at the input end into a buck charging voltage at the system end, or in a boost discharge mode to convert the system voltage at the system end into a boost discharge voltage at the input end. When the bidirectional voltage conversion circuit operates in the buck charging mode or the boost discharge mode, in each switching cycle, the first switch and the second switch are complementarily turned on and off, the third switch and the fifth switch remain turned on, the fourth switch remains turned off, and the sixth switch and the seventh switch are complementarily turned on and off, wherein the first switch and the sixth switch are turned on synchronously, wherein the buck charging voltage is less than the input voltage, and the boost discharge voltage is greater than the system voltage.

2. The bidirectional voltage conversion circuit as described in claim 1, when the bidirectional voltage conversion circuit operates in the buck charging mode, in each switching cycle, the buck duty cycle is determined by the input voltage and the buck charging voltage, and when the bidirectional voltage conversion circuit operates in the boost discharge mode, in each switching cycle, the boost duty cycle is determined by the system voltage and the boost discharge voltage.

3. The bidirectional voltage conversion circuit as described in claim 1 can also operate in a boost charging mode to convert the input voltage received at the input end into a boost charging voltage at the system end. When the bidirectional voltage conversion circuit operates in the boost charging mode, in each switching cycle, the first switch remains turned on, the second switch remains turned off, the third switch and the fourth switch are turned on and off complementarily, and the fifth switch remains turned off, wherein the boost charging voltage is greater than the input voltage.

4. The bidirectional voltage conversion circuit as described in claim 1 can also operate in a buck discharge mode to convert the system voltage at the system end into a buck discharge voltage at the input end. When the bidirectional voltage conversion circuit operates in the buck discharge mode, in each switching cycle, the first switch remains turned on, the second switch remains turned off, the third switch and the fourth switch are turned on and off complementarily, and the fifth switch remains turned off, wherein the system voltage is greater than the buck discharge voltage. 5 . The bidirectional voltage conversion circuit as claimed in claim 3 , wherein when the bidirectional voltage conversion circuit operates in a boost charging mode, in each switching cycle, the sixth switch remains turned on and the seventh switch remains turned off. 6 . The bidirectional voltage conversion circuit as claimed in claim 4 , wherein when the bidirectional voltage conversion circuit operates in a step-down discharge mode, in each switching cycle, the sixth switch remains turned on and the seventh switch remains turned off.

Images