TWI762415B - Buck-boost bidirectional DC-DC resonant converter and control method thereof - Google Patents

Abstract

A bidirectional DC-DC power conversion device includes a bidirectional DC-DC resonance converter and a control unit. The control unit generates a plurality of control signals for controlling the power converter, so that the power converter can operate in a plurality of different conversion modes according to the control signals to achieve bidirectional bidirectional between two sides of the power converter Buck-boost conversion. In particular, when the power converter converts the input voltage received by the second full-bridge chopper circuit to the output of the first full-bridge chopper circuit via the LLC resonant circuit while the control frequency of the second full-bridge chopper circuit is lower than the input voltage In the case of the resonant frequency of the side, when the LLC resonant circuit reaches resonance, the control of the first full-bridge chopper circuit is increased so that the output side can output a higher output voltage.

Description

Buck-boost bidirectional DC-DC resonant converter and control method thereof

The present invention relates to a DC-DC resonant converter, in particular to a bidirectional DC-DC resonant converter that can be stepped up and down and a control method thereof.

Existing DC-DC LLC power conversion circuits generally include a first full-bridge chopper circuit connected across a first side, a second full-bridge chopper circuit connected across a second side, and a coupling LLC resonant circuit between the first full bridge chopper circuit and the second full bridge chopper circuit. The first full-bridge chopper circuit is usually composed of four power-type switching elements, the second full-bridge chopper circuit is usually composed of four power-type switching elements, and the LLC resonant circuit is composed of a resonant capacitor, a It consists of a resonant inductor and a transformer.

However, for the operations of the first full-bridge chopper circuit and the second full-bridge chopper circuit, under the existing control mode, although the step-up or step-down from the first side to the second side can be realized Power conversion, but only buck conversion is possible from the second side to the first side. Therefore, how to control the LLC power conversion circuit to realize bidirectional step-up/step-down power conversion between the first side and the second side has become one of the issues to be solved in the related art.

Therefore, the purpose of the present invention is to provide a bidirectional DC-DC resonant converter with buck-boost and a control method thereof, which can overcome at least one disadvantage of the prior art.

Therefore, a bidirectional DC-DC power conversion device provided by the present invention includes a bidirectional DC-DC resonant converter and a control unit.

The bidirectional DC-DC resonant converter has a first side and a second side that can be used as input side and output side or output side and input side, respectively, and includes a first full-bridge chopper circuit, a second full-bridge chopper circuit A bridge chopper circuit, and an LLC resonant circuit. The first full-bridge chopper circuit includes first and second switch components and third and fourth switch components connected in series with each other and across the first side, wherein the first and third switch components and the second and fourth switch components The positive terminal and the negative terminal of the first side are respectively electrically connected, and the first to fourth switch components are turned on or off in response to the first to fourth control signals, respectively. The second full-bridge chopper circuit includes fifth and sixth switch elements and seventh and eighth switch elements connected in series with each other and across the second side, wherein the fifth and seventh switch elements and the sixth and eighth switch elements The positive terminal and the negative terminal of the second side are respectively electrically connected, and the fifth to eighth switch components are respectively turned on or off in response to the fifth to eighth control signals. The LLC resonant circuit is coupled between the first full-bridge chopper circuit and the second full-bridge chopper circuit, and includes a resonant capacitor, a resonant inductor and a transformer. The resonant capacitor, the resonant inductor and the primary winding of the transformer in series with each other are coupled at a first common node between the first and second switch components and a second between the third and fourth switch components Between the common nodes, the secondary winding of the transformer is coupled between a third common node between the fifth and sixth switch components and a fourth common node between the seventh and eighth switch components.

The control unit is electrically connected to the first and second full-bridge chopper circuits, and configured to generate and provide the first to eighth control signals for controlling the first to eighth switch elements, so that the bidirectional DC- The DC resonant converter is operable in one of the first to third conversion modes.

When the first side serves as an input side for receiving an input voltage and the second side serves as an output side for outputting an output voltage, the bidirectional DC-DC resonant converter operates in the first conversion mode, Wherein the control unit in each control cycle of the first full-bridge chopper circuit: make the first and fourth control signals identical to each other, so that the first and fourth switch components operate synchronously; make the second and third control signals are identical to each other and are complementary to the first and fourth control signals, so that the second and third switch components operate synchronously; the rising edge of one of the first/fourth control signal and the second/third control signal is connected to the other There is a first dead time between the falling edges of the first to fourth switch elements related to the switching speed of the first to fourth switch elements, so that the first and second switch elements are both turned off during the first dead time to avoid the The first and second switch components are turned on or both the third and fourth switch components are turned off to prevent the third and fourth switch components from being turned on; and the fifth to eighth switch components are turned off, so that the second full bridge is cut off The wave circuit is used as a full-wave rectifier circuit.

When the second side serves as an input side for receiving an input voltage and the first side serves as an output side for outputting an output voltage and the control frequency of the fifth to eighth switching elements is higher than a relative to the The bidirectional DC-DC resonant converter operates in the second conversion mode at the second side and at the resonant frequency associated with the resonant capacitor and the resonant inductor, wherein the control unit operates in each of the second full-bridge chopper circuit In one control period: make the fifth and eighth control signals the same as each other, so that the fifth and eighth switch components operate synchronously; make the sixth and seventh control signals the same and complementary to the fifth and eighth control signals, so that the The sixth and seventh switch components operate synchronously; there is one and the fifth to eighth switches between the rising edge of one of the fifth/eighth control signal and the sixth/seventh control signal and the falling edge of the other one The second dead time related to the switching speed of the components, so that the fifth and sixth switch components are both turned off during the second dead time to prevent the fifth and sixth switch components from being connected directly or the seventh and eighth switch components are both turned off. Turning off to prevent the seventh and eighth switch elements from being turned on; and turning off the first to fourth switch elements, so that the first full-bridge chopper circuit is used as a full-wave rectifier circuit.

When the second side acts as an input side for receiving an input voltage and the first side acts as an output side for outputting an output voltage and the control frequency of the fifth to eighth switching elements is lower than the resonance frequency , the bidirectional DC-DC resonant converter operates in the third conversion mode, wherein the control unit makes the fifth and eighth control signals identical to each other in each control period of the second full-bridge chopper circuit, so that The fifth and eighth switch elements operate synchronously; make the sixth and seventh control signals identical to each other and complementary to the fifth and eighth control signals so that the sixth and seventh switch elements operate synchronously; make the fifth/eighth control signals and The second dead time exists between the rising edge of one of the sixth/seventh control signals and the falling edge of the other, so that the fifth and sixth switch elements are both turned off during the second dead time In order to prevent the fifth and sixth switch assemblies from being connected directly or the seventh and eighth switch assemblies are both turned off to prevent the seventh and eighth switch assemblies from being connected directly; the first and third switch assemblies are turned off; the second switch assembly is made to respond During the conduction period of the fifth and eighth switch elements during the second control signal and when the resonant capacitor and the resonant inductor reach resonance, the resonant capacitor and the resonant inductor start to conduct and turn off synchronously with the fifth and eighth switch elements, so that in the first The resonant capacitor is charged by the induced current of the primary side winding during the conduction period of the two switch elements; and the fourth switch element is made to respond to the fourth control signal during the conduction period of the sixth and seventh switch elements and at When the resonant capacitor and the resonant inductor reach resonance, they start to conduct and turn off synchronously with the sixth and seventh switch elements, so that the resonant capacitor is connected to the resonant capacitor by the induced current of the primary side winding during the conduction period of the fourth switch element Charge.

Therefore, the above-mentioned control method of a bidirectional DC-DC resonant converter provided by the present invention includes the following steps: when an input power is converted from the first side to an output voltage output by the second side, in the second In each control cycle of a full-bridge chopper circuit: make the first and fourth control signals the same as each other; make the second and third control signals the same as each other and complementary to the first and fourth control signals; and make the first and fourth control signals the same / A first dead time related to the switching speed of the first to fourth switch elements is inserted between the rising edge of one of the fourth control signal and the second/third control signal and the falling edge of the other; When an input voltage is converted from the second side to an output voltage output from the first side and the control frequency of the fifth to eighth switching elements is higher than a relative to the second side and is related to the resonant capacitor and the resonant inductor In each control cycle of the second full-bridge chopper circuit: make the fifth and eighth control signals the same as each other; make the sixth and seventh control signals the same as each other and complementary to the fifth , Eight control signals; a switch with the fifth to eighth switch components is inserted between the rising edge of one of the fifth/eighth control signal and the sixth/seventh control signal and the falling edge of the other one speed-dependent second dead time; and when an input voltage is switched from the second side to an output voltage output from the first side and the control frequency of the fifth to eighth switching elements is lower than the resonant frequency, In each control period of the second full-bridge chopper circuit: make the fifth and eighth control signals the same as each other; make the sixth and seventh control signals the same as each other and complementary to the fifth and eighth control signals; A second dead zone related to the switching speed of the fifth to eighth switch elements is inserted between the rising edge of one of the fifth/eighth control signal and the sixth/seventh control signal and the falling edge of the other time; according to the second control signal, the second switch element starts to conduct during the conduction period of the fifth and eighth switch elements and when the resonant capacitor and the resonant inductor reach resonance, and is synchronized with the fifth and eighth switch elements turning off so that the resonant capacitor is charged by the induced current of the primary side winding during the conduction period of the second switch element; and the fourth switch element is connected to the sixth and seventh switch elements according to the fourth control signal During the conduction period and when the resonant capacitor and the resonant inductor reach resonance, the resonant capacitor and the resonant inductor start to conduct and turn off synchronously with the sixth and seventh switch components.

The effect of the present invention is that in the third conversion mode, the control unit can make the resonant capacitor in the resonant circuit be additionally charged by using the additional control of the second and fourth switch components, thereby realizing the bidirectional The DC-DC resonant circuit is boosted from the second side to the first side.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are designated by the same reference numerals.

Referring to FIG. 1 , a bidirectional DC-DC power conversion device according to an embodiment of the present invention is exemplarily shown. The bidirectional DC-DC power conversion device includes, for example, a bidirectional DC-DC resonant converter 10 and a control unit 20 for controlling the bidirectional DC-DC resonant converter 10 .

In this embodiment, the bidirectional DC-DC resonant converter 10 has a first side DC1 and a second side DC2, which can be used as input side and output side or output side and input side, respectively. The first side DC1 has a positive terminal DC1+ and a negative terminal DC1-, and the second side DC2 has a positive terminal DC2+ and a negative terminal DC2+. More specifically, when the first side DC1 is used as an input side, the first side DC1 is suitable for applying a DC input voltage; and when the second side DC2 is used as an input side, the second side DC2 Suitable for applying DC input voltage. The bidirectional DC-DC resonant converter 10 includes, for example, a first filter capacitor C1, a second filter capacitor C2, a first full-bridge chopper circuit 1, a second full-bridge chopper circuit 2, and an LLC resonant circuit 3.

Hereinafter, the circuit structure of the bidirectional DC-DC resonant converter 10 will be described in further detail with reference to FIG. 2 .

The first filter capacitor C1 is connected across the first side DC1, and the second filter capacitor C2 is connected across the second side DC2.

The first full-bridge chopper circuit 1 includes first to fourth switching elements K1 ˜ K4 . The first and second switch components K1, K2 are connected in series with each other and across the first side DC1, and the first and second switch components K1, K2 are respectively electrically connected to the positive terminal DC1+ and the negative terminal of the first side DC1 DC1-. The third and fourth switch components K3, K4 are connected in series with each other and across the first side DC1, and the third and fourth switch components K1, K2 are respectively electrically connected to the positive terminal DC1+ and the negative terminal of the first side DC1 DC1-. The first to fourth switch elements K1 ˜ K4 are turned on or off in response to the first to fourth control signals S1 ˜ S4 , respectively. In the present embodiment, each of the first to fourth switching elements includes, for example, a metal oxide semiconductor field effect transistor (hereinafter referred to as a MOSFET), such as an n-channel MOSFET, and an anti-parallel connection to the MOSFET. body diode, and the gate of this MOSFET is used to receive the corresponding control signals S1/S2/S3/S4. However, in other embodiments, each of the first to fourth switching elements K1 ˜ K4 may also include an insulated gate bipolar transistor (hereinafter referred to as IGBT). It is worth noting that when the MOSFETs of the first to fourth switching elements K1 ˜ K4 are turned off in response to the first to fourth control signals S1 ˜ S4 respectively, the first full-bridge chopper circuit 1 can use Make a full-wave rectifier circuit.

The second full-bridge chopper circuit 2 includes fifth to eighth switch elements K5 ˜ K8 . The fifth and sixth switch elements K5 and K6 are connected in series with each other and across the second side DC2, and the fifth and sixth switch elements K5 and K6 are respectively electrically connected to the positive terminal DC2+ and the negative terminal of the second side DC2 DC2-. The seventh and eighth switch elements K7 and K8 are connected in series with each other and are connected across the second side DC2, and the seventh and eighth switch elements K7 and K8 are respectively electrically connected to the positive terminal DC2+ and the negative terminal of the second side DC2 DC2-. The fifth to eighth switch elements K5 ˜ K8 are turned on or off in response to the fifth to eighth control signals S5 ˜ S8 , respectively. In the present embodiment, each of the fifth to eighth switch elements includes, for example, a MOSFET (eg, an n-channel MOSFET) and a body diode in anti-parallel with the MOSFET, wherein the gate of the MOSFET is for receiving corresponding control signals S5/S6/S7/S8. However, in other embodiments, each of the fifth to eighth switching elements K5 ˜ K8 may also include an IGBT. Similar to the first full-bridge chopper circuit 1, when the MOSFETs of the fifth to eighth switch elements K5-K8 are turned off in response to the fifth to eighth control signals S5-S8, respectively, the second full-bridge The bridge chopper circuit 2 can be used as a full-wave rectifier circuit.

The LLC resonant circuit 3 is coupled between the first full-bridge chopper circuit 1 and the second full-bridge chopper circuit 2 , and includes, for example, a resonant capacitor Cr, a resonant inductor Lr and a transformer T. The transformer T includes a primary winding L1 and a secondary winding L2. The resonant capacitor Cr, the resonant inductor Lr and the primary winding L1 are coupled to each other in series between the first common node n1 and the second common node n2 (one end of the resonant capacitor Cr is coupled to the first common node n1, the dotted end and the non-dotted end of the primary winding are respectively coupled to one end of the resonant inductor Lr and the second common node n2). The dotted end and the non-dotted end of the secondary winding L2 are respectively coupled to the third common node n3 and the fourth common node n4.

The control unit 20 is electrically connected to the first and second full-bridge chopper circuits (see FIG. 1 ), and is configured to generate and provide the first to eighth switching elements K1 to K8 (MOSFETs) The first to eighth control signals S1 ˜ S8 enable the bidirectional DC-DC resonant converter 10 to operate in one of the first to third conversion modes.

When the first side DC1 and the second side DC2 are used as an input side for receiving an input voltage and an output side for outputting an output voltage, respectively, the bidirectional DC-DC resonant converter 10 according to the control The first to fourth control signals S1 to S4 (or the first to eighth control signals S1 to S8 ) of the unit 20 operate in the first conversion mode. Referring to FIG. 3 , in the first conversion mode, the control unit 20 makes the first and fourth control signals S1 and S4 identical to each other in each control period T of the first full-bridge chopper circuit 1 so that the first and fourth control signals S1 and S4 are the same as each other. 1. The four switch components K1 and K4 operate synchronously; the second and third control signals S2 and S3 are identical to each other and complementary to the first and fourth control signals S1 and S4 so that the second and third switch components K2 and K3 operate synchronously ; Make the first/fourth control signal S1/S4 and the second/third control signal S2/S3 one of the rising edges and the falling edge of the other one exist between the first to fourth switch components The first dead time (eg t ₀ ~t ₁ and t ₂ ~t ₃ ) related to the switching speed of K1 ~ K4 , so that the first and second switch components K1 and K2 are both turned off during the first dead time. Avoid direct connection of the first and second switch components K1 and K2 during the switching process or the third and fourth switch components K3 and K4 are all turned off to avoid direct connection of the third and fourth switch components K3 and K4 during the switching process; and make the third and fourth switch components K3 and K4 pass through. The fifth to eighth switch elements K5 ˜ K8 are all turned off (for example, the control unit 20 stops outputting the fifth to eighth control signals S5 ˜ S8 , or outputs the signals kept at the logic-0 level (not shown) as the The fifth to eighth control signals S5-S8) so that the second full-bridge chopper circuit 2 can be used as a full-wave rectifier circuit. Please note that since the first dead time is related to the switching speed of the first to fourth switching elements K1 ˜ K4 , in this embodiment, the MOSFETs included in the first to fourth switching elements K1 ˜ K4 have relatively Faster switching speed, the first dead time can be, but not limited to, for example, a time in the range of 0.3µs to 0.5µs. In other embodiments, if the first to fourth switch components K1 to K4 include relative In the case of an IGBT with a slow switching speed, the first dead time can be, for example, a time in the range of 0.5µs to 1µs.

The four operating states of the bidirectional DC-DC resonant converter 10 operating in the first conversion mode in each control period T will be described in further detail below with reference to FIGS. 2 and 3 .

After the previous control period T ends, firstly, in the first working state corresponding to the first dead time t ₀ ˜t ₁ , the first to eighth switch components K1 ˜ K8 are all turned off to prevent the During the switching process, the _first and _second switch assemblies K1 and K2 are connected directly or the third and fourth switch assemblies K3 and K4 are connected through; The three switch components K2, K3 are turned on in response to the second and third control signals S2, S3, and the other switch components K1, K2, K5~K8 are all turned off, so corresponding to the first side DC1 (input side) received The input current of the input voltage flows through the turned-on third switch component K3, and then flows into the primary side winding L1 from the non-dot end of the primary side winding L1 and passes through the resonant inductor Lr and the resonant capacitor Cr (for (reverse) resonant charge), and finally flows through the second switch component K2 that is turned on, and at the same time, the induced current generated in the secondary winding L2 flows out from the non-dot end of the secondary winding L2 and passes through the seventh and sixth switches The body diodes of the components K7 and K6 finally flow into the secondary winding L2 through the dotted end of the secondary winding L2 to charge the second side DC2 (output side), thereby converting the input voltage into The output voltage output by the second side DC2; then, in the third working state corresponding to the first dead time t ₂ ˜t ₃ , similar to the above-mentioned first working state, the first to eighth switches The components K1 to K8 are all turned off to prevent the first and second switch components K1 and K2 from being connected directly or the _third and fourth switch components K3 and K4 being connected directly during the switching process; In the fourth working state of ₄ , the first and fourth switch components K1, K4 are turned on in response to the first and fourth control signals S1, S4, and the other switch components K2, K3, K5~K8 are all turned off, so the corresponding The input current of the input voltage received at the first side DC1 flows through the turned-on first switch element K1, the resonant inductor Lr and the resonant capacitor Cr, and then flows into the primary side winding L1 from the running end of the primary side winding L1. side winding L1 (for resonant charging), and finally flows through the fourth switch component K4 that is turned on, and at the same time, the induced current generated in the secondary side winding L2 flows out from the dot end of the secondary side winding L2 and passes through the fifth, The body diodes of the eight switch components K5 and K8 finally flow into the secondary side winding L2 through the non-dot end of the secondary side winding L2 to charge the second side DC2, thereby converting the input voltage into The output voltage of the DC2 output on this second side. After the control period T ends, it will enter the first working state of the next control period T, that is, the working state corresponding to the dead time t ₄ to t ₅ .

，其中L _r1代表寄生於該第二全橋斬波電路2的雜散電感與該諧振電感器Lr之電感共同作用的等效電感值(其可藉由實際量測而獲得)，且C _r1代表是寄生於該第二全橋斬波電路2的雜散電容與該諧振電容器Cr共同作用的等效電容值(其可藉由實際量測而獲得)。參閱圖4，在該第二轉換模式中，該控制單元20在該第二全橋斬波電路2的每一控制週期T’內：使該第五、八控制信號S5，S8彼此相同，以致該第五、八開關組件K5，K8同步操作；使該第六、七控制信號S6，S7彼此相同並互補於該第五、八控制信號S5，S8，以致該第六、七開關組件K6，K7同步操作；使該第五/八控制信號S5/S8和該第六/七控制信號S6/S7其中一者的上升緣與其中另一者的下降緣之間存在有一與該第五至第八開關組件K5~K8的切換速度有關的第二死區時間(如t ^’ ₀~t ^’ ₁和t ^’ ₂~t ^’ ₃)以致在該第二死區時間內該第五、六開關組件K5，K6均關斷以避免在切換過程中該第五、六開關組件K5，K6直通或者該第七、八開關組件K7，K8均關斷以避免在切換過程中該第七、八開關組件K7，K8直通；及使該第一至第四開關組件K1~K4均關斷(例如，該控制單元20停止輸出該第一至第四控制信號S1~S4，或輸出保持在邏輯-0準位的信號(圖未示)作為該第一至第四控制信號S1~S4)，以致該第一全橋斬波電路1用作一全波整流電路。在本實施例中，由於該第五至第八開關組件K5~K8相似於該第一至第四開關組件K1~K4(即包含n-通道MOSFET)，所以該控制週期T’可相似於該第一轉換模式中的該控制週期T，且該第二死區時間可相似於該第一轉換模式中的該第一死區時間。 When the second side DC2 is an input side for receiving an input voltage and the first side is an output side for outputting an output voltage and the first side is an output side for outputting an output voltage and the control frequency of the fifth to eighth switching elements K5~K8 When higher than a resonant frequency relative to the second side DC2 and related to the resonant capacitor Cr and the resonant inductor Lr, the bidirectional DC-DC resonant converter 10 The control signals S5 - S8 (or the first to eighth control signals S1 - S8 ) operate in the second conversion mode. It is worth noting that this resonant frequency can be expressed as

, where L _r1 represents the equivalent inductance value of the stray inductance parasitic in the second full-bridge chopper circuit 2 and the inductance of the resonant inductor Lr (which can be obtained by actual measurement), and C _r1 It represents the equivalent capacitance value (which can be obtained by actual measurement) of the stray capacitance parasitic on the second full-bridge chopper circuit 2 and the resonant capacitor Cr acting together. Referring to FIG. 4, in the second conversion mode, the control unit 20 makes the fifth and eighth control signals S5 and S8 identical to each other in each control period T' of the second full-bridge chopper circuit 2, so that The fifth and eighth switch components K5 and K8 operate synchronously; the sixth and seventh control signals S6 and S7 are identical to each other and are complementary to the fifth and eighth control signals S5 and S8, so that the sixth and seventh switch components K6, K7 operates synchronously; there is a relationship between the rising edge of one of the fifth/eighth control signal S5/S8 and the sixth/seventh control signal S6/S7 and the falling edge of the other The second dead time (eg t ^' ₀ ~ t ^' ₁ and t ^' ₂ ~ t ^' ₃ ) related to the switching speed of the eight switch assemblies K5 ~ K8 so that the fifth and sixth switch assemblies are within the second dead time. Both K5 and K6 are turned off to prevent the fifth and sixth switch assemblies K5 and K6 from being connected during the switching process or the seventh and eighth switch assemblies K7 and K8 are all turned off to avoid the seventh and eighth switch assemblies during the switching process. K7, K8 are turned on; and all the first to fourth switch components K1 to K4 are turned off (for example, the control unit 20 stops outputting the first to fourth control signals S1 to S4, or the output remains at the logic-0 level Bit signals (not shown) are used as the first to fourth control signals S1 ˜ S4 ), so that the first full-bridge chopper circuit 1 functions as a full-wave rectifier circuit. In this embodiment, since the fifth to eighth switching elements K5 ˜ K8 are similar to the first to fourth switching elements K1 ˜ K4 (ie, include n-channel MOSFETs), the control period T′ can be similar to the The control period T in the first conversion mode, and the second dead time may be similar to the first dead time in the first conversion mode.

For example, the control period of the second full-bridge chopper circuit 2 is, for example, 6 μs (as shown in FIG. 4 ), and the resonant frequency is, for example, about 142 KHz (ie, the resonance period is about 7 μs). In this case, since the control frequencies of the fifth to eighth switching elements K5 ˜ K8 are higher than the resonant frequency, the bidirectional DC-DC resonant converter 10 operates in the second conversion mode. The four operating states of the bidirectional DC-DC resonant converter 10 operating in the second conversion mode in each control period T' will be described in further detail below with reference to FIG. 2 and FIG. 4 .

After the previous control period T' ends, firstly, in the first working state corresponding to the second dead time t' ₀ ~ t' ₁ , the first to eighth switch components K1 ~ K8 are all turned off, In order to prevent the direct connection of the fifth and sixth switch assemblies K5 and K6 or the direct connection of the seventh and eighth switch assemblies K7 and K8 during the switching process; then, in the second working state corresponding to time t' ₁ ~ t' ₂ , the fifth and eighth switch components K5, K8 are turned on in response to the fifth and eighth control signals S5, S8, and the other switch components K1~K4, K6, K7 are all turned off, so corresponding to the second side DC2 ( The input current of the input voltage received by the input side) flows through the conductive fifth switch component K5, and then flows into the secondary winding L2 from the dot end of the secondary winding L2, and finally flows through the conductive eighth Switch component K8, while the induced current generated in the primary side winding L1 flows out from the dot end of the primary side winding L1 and passes through the resonant inductor Lr and the resonant capacitor Cr (for resonant charging), and finally flows through the first, The body diodes of the four switch assemblies K1, K4 charge the first side DC1 (output side), thereby converting the input voltage into an output voltage output at the first side DC1; In the third working state of the second dead zone time t' ₂ ˜t' ₃ , similar to the above-mentioned first working state, the first to eighth switch components K1 ˜ K8 are all turned off to prevent the The fifth and sixth switch assemblies K5 and K6 are connected directly or the seventh and eighth switch assemblies K7 and K8 are connected directly; finally, in the fourth working state corresponding to the time t' ₃ to t' ₄ , the sixth and seventh switches The components K6, K7 are turned on in response to the sixth and seventh control signals S6, S7, and the other switch components K1~K4, K5, K8 are turned off, so the input current corresponding to the input voltage received by the second side DC2 It flows through the conductive seventh switch component K7, then flows into the secondary winding L2 from the non-dot end of the secondary winding L2, and finally flows through the conductive sixth switch component K6, while the primary winding L1 The generated induced current flows out from the non-dot end of the primary side winding L1 and passes through the body diodes of the third and second switch components K3 and K2, the resonant capacitor Cr and the resonant inductor Lr, and finally passes through the primary side winding. The dotted end of L1 returns to the primary side winding L1 to charge the first side DC1, thereby converting the input voltage into an output voltage at the output of the first side DC1. After the control period T' ends, it will enter the first working state of the next control period T', that is, the working state corresponding to the dead time t' ₄ to t' ₅ .

When the second side DC2 is an input side for receiving an input voltage and the first side DC1 is an output side for outputting an output voltage and the control frequency of the fifth to eighth switching elements is lower than At the resonant frequency, the bidirectional DC-DC resonant converter 10 according to the second and fourth control signals from the control unit 20 and the fifth to eighth control signals S5 to S8 (or the first to eighth control signals S1~S8) and operate in the third conversion mode. Referring to FIG. 5 , in the third conversion mode, the control unit 20 makes the fifth and eighth control signals S5 and S8 the same as each other in each control period T″ of the second full-bridge chopper circuit 2 , so that The fifth and eighth switch elements K5, K8 operate synchronously; the sixth and seventh control signals S6, S7 are identical to each other and are complementary to the fifth and eighth control signals S5, S8, so that the sixth and seventh switch elements K6, K7 Synchronous operation; make the second dead time exist between the rising edge of one of the fifth/eighth control signal S5/S8 and the sixth/seven control signal S6/S7 and the falling edge of the other one so that During the second dead time, the fifth and sixth switch components are both turned off to prevent the fifth and sixth switch components from being turned on during the switching process or the seventh and eighth switch components are both turned off to avoid the The seventh and eighth switch components are turned on; the first and third switch components are turned off (for example, the control unit 20 stops outputting the first and third control signals S1, S3, or outputs a signal maintained at a logic-0 level ( Not shown) as the first and third control signals S1, S3); make the second switch element K2 respond to the second control signal S2 during the conduction period of the fifth and eighth switch elements K5, K8 and during the When the resonant capacitor Cr and the resonant inductor Lr reach resonance, they start to conduct and turn off synchronously with the fifth and eighth switch elements K5 and K8, so that during the conduction period of the second switch element K2, through the primary side winding L1 Induction current charges the resonant capacitor Cr; and causes the fourth switch element K4 to respond to the fourth control signal S4 during the conduction period of the sixth and seventh switch elements K6, K7 and during the resonant capacitor Cr and the resonant inductance When the device Lr reaches resonance, it starts to conduct and turns off synchronously with the sixth and seventh switch elements K6 and K7, so that the resonant capacitor Cr is connected to the resonant capacitor Cr by the induced current of the primary side winding L1 during the conduction period of the fourth switch element K4. Charge.

For example, the control period of the second full-bridge chopper circuit 2 is, for example, 10µs (as shown in FIG. 5 ), and the resonance frequency is about 142KHz (ie, the resonance period is about 7µs). In this case, since the control frequencies of the fifth to eighth switching elements K5 ˜ K8 are lower than the resonant frequency, the bidirectional DC-DC resonant converter 10 operates in the third conversion mode. The six operating states of the bidirectional DC-DC resonant converter 10 operating in the third conversion mode in each control period T″ will be described in further detail below with reference to FIG. 2 and FIG. 5 .

After finishing the previous control period T", firstly, in the first working state corresponding to the second dead time t" ₀ ~ t" ₁ , the first to eighth switch components K1 ~ K8 are all turned off, In order to prevent the direct connection of the fifth and sixth switch assemblies K5 and K6 or the direct connection of the seventh and eighth switch assemblies K7 and K8 during the switching process; then, in the second working state corresponding to time t" ₁ ~ t" ₂ , the fifth and eighth switch components K5, K8 are turned on in response to the fifth and eighth control signals S5, S8, and the other switch components K1~K4, K6, K7 are all turned off, so corresponding to the second side DC2 ( The input current of the input voltage received by the input side) flows through the conductive fifth switch component K5, and then flows into the secondary winding L2 from the dot end of the secondary winding L2, and finally flows through the conductive eighth Switch component K8, while the induced current generated in the primary side winding L1 flows out from the dot end of the primary side winding L2 and passes through the resonant inductor Lr and the resonant capacitor Cr (for resonant charging), and finally flows through the first, The body diodes of the four-switch assemblies K1, K4 charge the first side DC1 (output side), in particular, the resonant circuit 3 completes the resonance at the time point t"₂; In the third working state from time t" ₂ to t" ₃ , the fifth and eighth switch elements K5 and K8 are continuously turned on in response to the fifth and eighth control signals S5 and S8, and the second switch element K2 is in response to the The second control signal S2 is turned on, so the electric energy corresponding to the input voltage continues to be transmitted to the first side DC1. Since the second switch element K2 is turned on, the induced current generated by the primary side winding L1 continues to flow through the first side DC1. The resonant inductor Lr, the resonant capacitor Cr, the body diodes of the second switch component K2 and the fourth switch component K4 finally return to the primary side winding L1, so that the resonant capacitor Cr can continue to be resonantly charged (until time Point t" ₃ ends charging) so that the potential of one end (ie, the right end in Fig. 2 ) of the resonant capacitor Cr coupled to the resonant inductor Lr is charged high for commutation charging for the subsequent second half of the control cycle Prepare; then, in the fourth working state corresponding to the second dead time t" ₃ ~ t" ₄ , similar to the first working state described above, the first to eighth switch components K1 ~ K8 are all turned off to prevent the fifth and sixth switch assemblies K5 and K6 from being switched on or the seventh and eighth switch assemblies K7 and K8 from being switched on during the switching process; then, at the fifth operation corresponding to the time t" ₄ ~ t" ₅ In the state, the sixth and seventh switch components K6, K7 are turned on in response to the sixth and seventh control signals S6, S7, and the other switch components K1~K4, K5, K8 are all turned off, so corresponding to the second side The input current of the input voltage received by DC2 flows through the turned-on seventh switch element K7, then flows into the secondary side winding L2 from the non-dot end of the secondary side winding L2, and finally flows through the turned-on sixth switch element K6, at the same time, the induced current generated in the primary side winding L1 flows out from the non-dot end of the primary side winding L1 and passes through the body diodes of the second and third switch components K2 and K3, the resonant capacitor Cr and the resonant inductance The device Lr is finally returned to the primary side winding L1 through the dotted end of the primary side winding L1 to charge the first side DC1, especially at the time point t" ₅ , the resonant circuit 3 completes the resonance; In the sixth working state corresponding to time t" ₅ ~t" ₆ , the sixth and seventh switch components K6, K7 are continuously turned on in response to the sixth and seventh control signals S6, S7, and the fourth switch The element K4 is turned on in response to the fourth control signal S4, so the electric energy corresponding to the input voltage continues to be transmitted to the first side DC1. Since the fourth switch element K4 has been turned on, the induction generated by the primary side winding L1 The current continues to flow through the fourth switch element K4, the body diode of the second switch element K2, the resonant capacitor Cr and the resonant inductor Lr and finally returns to the primary side winding L1, so that the resonant capacitor Cr can continue to flow. Resonant charging (until time point t" ₆ ends charging) so that the potential of one end (ie, the left end in FIG. 2 ) of the resonant capacitor Cr coupled to the first common node n1 is charged high for the subsequent next Prepare for commutation charging in the first half of the control period T". After this control period T" ends, it will enter the first working state of the next control period T", that is, the working state corresponding to the dead time t" ₆ ~ t" ₇ .

To sum up, since in the third conversion mode, the control unit 20 can make the resonant capacitor Cr of the resonant circuit 3 be additionally charged by using the additional control of the second and fourth switch components K2 and K4, thereby This realizes the boosting of the bidirectional DC-DC resonant circuit 10 from the second side DC2 to the first side DC1. Therefore, the bidirectional DC-DC power conversion device of the present invention can indeed achieve the object of the present invention.

However, the above are only examples of the present invention, and should not limit the scope of implementation of the present invention. Any simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the contents of the patent specification are still included in the scope of the present invention. within the scope of the invention patent.

10: Bidirectional DC-DC Resonant Converter 1: The first full-bridge chopper circuit 2: Second full bridge chopper circuit 3: LLC resonant circuit 20: Control unit C1: The first filter capacitor C2: Second filter capacitor K1~K8: The first to eighth switch components Cr: resonant capacitor Lr: resonant inductor T: Transformer L1: Primary side winding L2: Secondary winding n1~n4: The first to fourth common nodes DC1: first side DC1+: positive terminal DC1-: negative terminal DC2: Second side DC2+: positive terminal DC2-: negative terminal S1~S4: first to fourth control signals S5~S8: Fifth to eighth control signals

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: FIG. 1 is a circuit block diagram exemplarily illustrating a bidirectional DC-DC power conversion device according to an embodiment of the present invention; FIG. 2 is a circuit diagram exemplarily illustrating a bidirectional DC-DC resonant converter of this embodiment; FIG. 3 is a timing diagram exemplarily illustrating first to fourth control signals generated by a control unit when the embodiment operates in the first conversion mode; FIG. 4 is a timing diagram exemplarily illustrating fifth to eighth control signals generated by the control unit when the embodiment operates in the second conversion mode; and FIG. 5 is a timing diagram exemplarily illustrating second, fourth, fifth to eighth control signals generated by the control unit when the embodiment operates in the third conversion mode.

10: Bidirectional DC-DC Resonant Converter

1: The first full-bridge chopper circuit

2: Second full bridge chopper circuit

3: LLC resonant circuit

20: Control unit

C1: The first filter capacitor

C2: Second filter capacitor

DC1: first side

DC1+: positive terminal

DC1-: negative terminal

DC2: Second side

DC2+: positive terminal

DC2-: negative terminal

S1~S4: first to fourth control signals

S5~S8: Fifth to eighth control signals

Claims (5)

A bidirectional DC-DC power conversion device, comprising: A bidirectional DC-DC resonant converter having a first side and a second side usable as input side and output side or output side and input side, respectively, and comprising: A first full-bridge chopper circuit, comprising first and second switch components and third and fourth switch components connected in series with each other and across the first side, wherein the first and third switch components and the second and fourth switches The components are respectively electrically connected to the positive terminal and the negative terminal of the first side, and the first to fourth switch components are respectively turned on or off in response to the first to fourth control signals; A second full-bridge chopper circuit, comprising fifth and sixth switch elements and seventh and eighth switch elements connected in series with each other and across the second side, wherein the fifth and seventh switch elements and the sixth and eighth switches The components are respectively electrically connected to the positive terminal and the negative terminal of the second side, and the fifth to eighth switch components are respectively turned on or off in response to the fifth to eighth control signals; and An LLC resonant circuit is coupled between the first full-bridge chopper circuit and the second full-bridge chopper circuit, and includes a resonant capacitor, a resonant inductor and a transformer, the resonant capacitor, the resonant capacitor and the transformer are connected in series with each other. The resonant inductor and the primary winding of the transformer are coupled between a first common node between the first and second switch components and a second common node between the third and fourth switch components, the transformer's the secondary winding is coupled between a third common node between the fifth and sixth switch elements and a fourth common node between the seventh and eighth switch elements; and a control unit, electrically connected to the first and second full-bridge chopper circuits, and configured to generate and provide the first to eighth control signals for controlling the first to eighth switch elements, so that the bidirectional direct current - the DC resonant converter is operable in one of the first to third conversion modes; Wherein, when the first side is used as an input side for receiving an input voltage and the second side is used as an output side for outputting an output voltage, the bidirectional DC-DC resonant converter operates at the first conversion mode, wherein the control unit in each control cycle of the first full-bridge chopper circuit: makes the first and fourth control signals identical to each other, so that the first and fourth switch components operate synchronously; makes the second and third The control signals are identical to each other and are complementary to the first and fourth control signals, so that the second and third switch components operate synchronously; There is a first dead time between the falling edges of the other and the switching speeds of the first to fourth switch components, so that the first and second switch components are both turned off during the first dead time. Prevent the first and second switch components from being connected directly or the third and fourth switch components are both turned off to prevent the third and fourth switch components from being connected directly; and turn off the fifth to eighth switch components, so that the second all The bridge chopper circuit is used as a full-wave rectifier circuit; Wherein, when the second side is used as an input side for receiving an input voltage and the first side is used as an output side for outputting an output voltage and the control frequency of the fifth to eighth switch components is higher than a relative On the second side and at the resonant frequency associated with the resonant capacitor and the resonant inductor, the bidirectional DC-DC resonant converter operates in the second conversion mode, wherein the control unit operates in the second full-bridge chopper circuit In each control cycle of: make the fifth and eighth control signals identical to each other, so that the fifth and eighth switch components operate synchronously; make the sixth and seventh control signals identical to each other and complementary to the fifth and eighth control signals, So that the sixth and seventh switch components operate synchronously; between the rising edge of one of the fifth/eighth control signal and the sixth/seventh control signal and the falling edge of the other, there is one and the fifth to the fifth The second dead time related to the switching speed of the eight switch components, so that the fifth and sixth switch components are both turned off during the second dead time to prevent the fifth and sixth switch components from being turned on or the seventh and eighth switches turning off the elements to prevent the seventh and eighth switch elements from being turned on; and turning off the first to fourth switch elements, so that the first full-bridge chopper circuit functions as a full-wave rectifier circuit; and Wherein, when the second side is used as an input side for receiving an input voltage and the first side is used as an output side for outputting an output voltage and the control frequency of the fifth to eighth switch components is lower than the At the resonant frequency, the bidirectional DC-DC resonant converter operates in the third conversion mode, wherein the control unit makes the fifth and eighth control signals identical to each other in each control cycle of the second full-bridge chopper circuit , so that the fifth and eighth switch components operate synchronously; make the sixth and seventh control signals identical to each other and complementary to the fifth and eighth control signals so that the sixth and seventh switch components operate synchronously; make the fifth/eighth control signal The second dead time exists between the rising edge of one of the signal and the sixth/seventh control signal and the falling edge of the other, so that the fifth and sixth switch elements are both within the second dead time. Turn off to prevent the fifth and sixth switch assemblies from being connected directly or both the seventh and eighth switch assemblies are turned off to prevent the seventh and eighth switch assemblies from being connected directly; turn off the first and third switch assemblies; turn off the second switch In response to the second control signal, the element starts to conduct during the conduction period of the fifth and eighth switch elements and when the resonant capacitor and the resonant inductor reach resonance and is turned off synchronously with the fifth and eighth switch elements, so as to be in the During the conduction period of the second switch element, the resonant capacitor is charged by the induced current of the primary side winding; and the fourth switch element is made to respond to the fourth control signal during the conduction period of the sixth and seventh switch elements And when the resonant capacitor and the resonant inductor reach resonance, they start to conduct and turn off synchronously with the sixth and seventh switch elements, so that the fourth switch element is turned off by the induced current of the primary winding during the conduction period of the fourth switch element. resonant capacitor charging. The bidirectional DC-DC power conversion device of claim 1, wherein the first to fourth switch components are identical to each other, and each of which includes a metal oxide semiconductor field effect transistor (MOSFET) or an insulated gate Bipolar Transistor (IGBT). The bidirectional DC-DC power conversion device of claim 1, wherein the fifth to eighth switch elements are identical to each other, and each of which includes a metal oxide semiconductor field effect transistor (MOSFET) or an insulated gate Bipolar Transistor (IGBT). The bidirectional DC-DC power conversion device according to claim 1, wherein the bidirectional DC-DC resonant converter further comprises a first filter capacitor and a second filter capacitor respectively connected across the first side and the second side filter capacitor. A control method for a bidirectional DC-DC resonant converter as claimed in claim 1, comprising: When an input power is converted from the first side to an output voltage output by the second side, in each control cycle of the first full-bridge chopper circuit: make the first and fourth control signals the same as each other; make the first and fourth control signals identical to each other; The second and third control signals are identical to each other and are complementary to the first and fourth control signals; and the rising edge of one of the first/fourth control signal and the second/third control signal and the falling edge of the other one A first dead time related to the switching speed of the first to fourth switch components is inserted between the edges; When an input voltage is converted from the second side to an output voltage output from the first side and the control frequency of the fifth to eighth switching elements is higher than a relative to the second side and is related to the resonant capacitor and the resonant inductor In each control cycle of the second full-bridge chopper circuit: make the fifth and eighth control signals the same as each other; make the sixth and seventh control signals the same as each other and complementary to the fifth , Eight control signals; a switch with the fifth to eighth switch components is inserted between the rising edge of one of the fifth/eighth control signal and the sixth/seventh control signal and the falling edge of the other one speed-related second dead time; and When an input voltage is converted from the second side to an output voltage output by the first side and the control frequency of the fifth to eighth switching elements is lower than the resonant frequency, in the second full-bridge chopper circuit In each control cycle: make the fifth and eighth control signals the same as each other; make the sixth and seventh control signals the same as each other and complementary to the fifth and eighth control signals; make the fifth/eighth control signal and the sixth A second dead time related to the switching speed of the fifth to eighth switch elements is inserted between the rising edge of one of the seven control signals and the falling edge of the other one; according to the second control signal, the The second switch element starts to conduct during the conduction period of the fifth and eighth switch elements and when the resonant capacitor and the resonant inductor reach resonance and is turned off synchronously with the fifth and eighth switch elements, so that the second switch element is turned off The resonant capacitor is charged by the induced current of the primary side winding during the on-time of the resonant capacitor; and according to the fourth control signal, the fourth switch element is in the on-period of the sixth and seventh switch elements and between the resonant capacitor and the resonant capacitor. When the resonant inductor reaches resonance, it starts to conduct and turns off synchronously with the sixth and seventh switch components.

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