CN106329934A - A control method and control device for a bidirectional resonant converter - Google Patents

Abstract

The present invention provides a control method and a control device for a bidirectional resonant converter. By adopting the solution provided by the present invention, the gain can be greater than 1 when energy flows in the reverse direction in the bidirectional resonant converter. The control method includes: when the energy in the bidirectional resonant converter is transferred from the second chopping part to the first chopping part, that is, when the energy flows in the opposite direction, controlling the output voltage of the resonance part to be a specified voltage Vset within a specified period of time; wherein , -Vh<Vset<+Vh, Vh is the output voltage of the first chopping part.

Description

A control method and control device for a bidirectional resonant converter

technical field

The invention relates to the technical field of power electronics, in particular to a control method and a control device for a bidirectional resonant converter.

Background technique

The bidirectional resonant converter is widely used in DC/DC conversion due to its high efficiency. The existing bidirectional resonant converter includes a first chopping part, a resonant part and a second chopping part connected in sequence; as shown in Figure 1 , the resonant part may specifically include a resonant inductor Lr, a resonant capacitor Cr and a transformer T; the first chopping part may specifically be the full-bridge chopping circuit shown in Figure 1, or other chopping circuits such as a multi-level chopping circuit ; The second chopping part can specifically be the full-wave chopping single circuit shown in FIG. 1 , or can be other chopping circuits such as a full-bridge chopping circuit.

Taking the bidirectional resonant converter shown in Figure 1 as an example, the control scheme of the existing bidirectional resonant converter is described:

When the energy in the bidirectional resonant converter is transferred from the first chopping part to the second chopping part, that is, when the energy flows in the forward direction, the first chopping part acts as an inverter to perform the inversion action, and the switching tubes Q1 and Q4 are synchronized On and off, the switching tubes Q2 and Q3 are on and off synchronously, the switching tubes Q1 and Q2 are complementary on and off, and the switching tubes Q2 and Q4 are complementary on and off; the second chopping part acts as a rectifier to perform rectification, and the switching tubes Q5 and Q6 can be rectified synchronously. It can also be turned off all the time; at this time, the gain of the bidirectional resonant converter can be greater than 1;

When the energy in the bidirectional resonant converter is transferred from the second chopping part to the first chopping part, that is, when the energy flows in the opposite direction, the first chopping part acts as a rectifier to perform rectification, and the switching tubes Q1, Q2, Q3, Q4 It can be rectified synchronously, or it can be turned off all the time; the second chopping part is used as an inverter to perform inverting action, and the switching tubes Q5 and Q6 are complementary on and off; at this time, the bidirectional resonant converter is essentially a series resonant circuit without boost function, its gain cannot be greater than 1.

Contents of the invention

The invention provides a control method and a control device of a bidirectional resonant converter, which are used to solve the problem that the gain cannot be greater than 1 when the energy flows in the reverse direction in the bidirectional resonant converter.

The present invention provides a control method for a bidirectional resonant converter. The bidirectional resonant converter includes a first chopping part, a resonant part and a second chopping part connected in sequence. The method includes:

When the energy in the bidirectional resonant converter is transferred from the second chopper part to the first chopper part, the output voltage of the resonant part is controlled to be a specified voltage Vset within a specified period; where -Vh <Vset<+Vh, Vh is the output voltage of the first chopping part.

The present invention also provides a control device for a bidirectional resonant converter. The bidirectional resonant converter includes a first chopping part, a resonant part and a second chopping part connected in sequence. The device includes:

The first control unit is configured to control the output voltage of the resonant part to be a specified value within a specified period when energy in the bidirectional resonant converter is transferred from the second chopping part to the first chopping part. Voltage Vset; wherein, -Vh<Vset<+Vh, Vh is the output voltage of the first chopping part.

The beneficial effects of the present invention are as follows:

In the solution provided by the embodiment of the present invention, when the energy in the bidirectional resonant converter is transferred from the second chopper part to the first chopper part, that is, when the energy flows in the opposite direction, the output voltage of the resonant part is controlled to be within a specified period of time A specified voltage Vset; where -Vh<Vset<+Vh, Vh is the output voltage of the first chopping part; that is, within the specified period, the second chopping part transfers energy to the resonant part, and the resonant part stores energy. After a specified period of time, the bidirectional resonant converter works normally, the resonant part releases energy, and transfers the energy to the second chopper part, that is, the bidirectional resonant converter has a boost function at this time, and the gain is greater than 1 when the energy flows in the reverse direction.

Description of drawings

FIG. 1 is a schematic diagram of an existing bidirectional resonant converter;

2 is one of the schematic diagrams of the driving signals of the switching tubes in the bidirectional resonant converter provided in Embodiment 1 of the present invention;

Fig. 3 is the second schematic diagram of the driving signal of the switching tube in the bidirectional resonant converter provided by Embodiment 1 of the present invention;

FIG. 4 is the third schematic diagram of the driving signal of the switching tube in the bidirectional resonant converter provided in Embodiment 1 of the present invention;

FIG. 5 is the fourth schematic diagram of the driving signals of the switching tubes in the bidirectional resonant converter provided in Embodiment 1 of the present invention;

6 is one of the schematic diagrams of the current path of the bidirectional resonant converter provided in Embodiment 1 of the present invention;

FIG. 7 is the second schematic diagram of the current path of the bidirectional resonant converter provided by Embodiment 1 of the present invention;

FIG. 8 is the third schematic diagram of the current path of the bidirectional resonant converter provided by Embodiment 1 of the present invention.

detailed description

Embodiments of the present invention provide a control method and a control device for a bidirectional resonant converter, which are used to realize a gain greater than 1 when energy flows in the reverse direction in the bidirectional resonant converter. The preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention. And in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

Example 1:

Embodiment 1 of the present invention provides a control method for a bidirectional resonant converter. The bidirectional resonant converter includes a first chopping part, a resonant part, and a second chopping part connected in sequence. The control method includes:

When the energy in the bidirectional resonant converter is transferred from the second chopper part to the first chopper part, that is, when the energy flows in the opposite direction, the output voltage of the resonant part is controlled to be the specified voltage Vset within a specified period of time; where -Vh< Vset<+Vh, Vh is the output voltage of the first chopping part.

Further, the output voltage of the resonance part is controlled to be +Vh or -Vh in periods other than the specified period.

That is, within the specified period, the second chopping part transfers energy to the resonance part, and the resonance part stores energy. After the specified period, the bidirectional resonant converter works normally, the resonance part releases energy, and transfers the energy to the second chopping part , at this time, the bidirectional resonant converter has a boost function, so the gain is greater than 1 when the energy flows in the reverse direction.

It should be noted that the control method provided by Embodiment 1 of the present invention does not specifically limit the specific number, duration, and occurrence position of the specified period, as long as the specified period exists, the reverse flow of energy in the bidirectional resonant converter can be realized When the gain is greater than 1. In order to be easy to implement in actual implementation, the specified time period can be set at the start position of the conduction period of the switch tube in each switching cycle of each switch tube in the second chopping part, that is, the output voltage of the control resonance part is at the specified The specified voltage Vset within the period may specifically include: for each switching tube in the second chopping part, in each switching period of the switching tube, control the output voltage of the resonance part from the moment when the switching tube is turned on It is a specified voltage Vset within a specified period of time.

In actual implementation, the output voltage of the resonant part can be controlled to be a specified voltage Vset within a specified period of time by controlling the on-off of the switch tube in the first chopping part. After the specified time period, the switching tubes in the first chopping part are controlled for synchronous rectification, and the output voltage of the resonant part is +Vh or -Vh.

Further, when the energy in the bidirectional resonant converter is transferred from the second chopping part to the first chopping part, that is, when the energy flows in the opposite direction, adjusting the switching frequency of the switching tube in the second chopping part can also affect the bidirectional The gain of the resonant converter plays a certain role in regulation, but when the switching frequency of the switching tube in the second chopping part is lower than the resonant frequency generated by the resonant inductance and resonant capacitor in the resonant part, the soft switching condition will be lost, and there will be a shoot-through risk. Therefore, preferably, the control method of the bidirectional resonant converter provided by Embodiment 1 of the present invention further includes: when the energy in the bidirectional resonant converter is transferred from the second chopper part to the first chopper part, controlling the second The switching frequency of the switching tube in the chopping part is greater than or equal to the resonance frequency generated by the resonant inductance and resonant capacitor in the resonant part. At this time, the risk of shoot-through of the switch tube in the second chopping part can be avoided, thereby improving the reliability and efficiency of the bidirectional resonant converter.

The following takes the bidirectional resonant converter shown in FIG. 1 as an example to describe the control method provided by Embodiment 1 of the present invention in detail.

When the energy in the bidirectional resonant converter shown in Figure 1 is transferred from the first chopping part to the second chopping part, that is, when the energy flows forward, the control method of the prior art can be used, and the gain of the bidirectional resonant converter Greater than 1 can be achieved.

When the energy in the bidirectional resonant converter shown in Figure 1 is transferred from the second chopping part to the first chopping part, that is, when the energy flows in the opposite direction, a switching frequency fset can be set, and the switching frequency fset is greater than or equal to the resonance The resonant frequency produced by the resonant inductance and resonant capacitor in the part controls the switching frequency of the switching tubes Q5 and Q6 in the second chopper part to be greater than or equal to the switching frequency fset to ensure reliability; on this basis, if the gain is not required to be greater than 1. The switching tubes Q1, Q2, Q3, and Q4 in the first chopping part can be controlled by using the control method of the prior art, and the output voltage of the resonant part is always +Vh or -Vh; if the gain is required to be greater than 1, then The control method provided in Embodiment 1 of the present invention can be used to control the output voltage of the resonant part to be a specified voltage Vset within a specified period, and to be +Vh or -Vh in other periods other than the specified period.

Preferably, the above specified voltage Vset is 0, which is easier to realize. Specifically, in each switching period of the switching tube Q5 in the second chopping part, the output voltage of the resonant part can be controlled by controlling the switching of the switching tubes Q1, Q2, Q3, and Q4 in the first chopping part. Vba is 0 within the specified time period starting from the conduction moment of the switching tube Q5, and then controls the switching tubes Q1, Q2, Q3, and Q4 for synchronous rectification; similarly, in each switching cycle of the switching tube Q6 in the second chopping part , by controlling the on-off of the switching tubes Q1, Q2, Q3, and Q4 in the first chopping part, the output voltage Vba of the resonant part is controlled to be 0 within a specified period of time starting from the moment when the switching tube Q6 is turned on, and then the switching tube is controlled to Q1, Q2, Q3, Q4 are synchronously rectified. The synchronous rectification control method is very mature in the industry, and will not be described in detail here. During specific implementation, considering the dead time, the driving signals g1, g2, g3, g4 of the switching tubes Q1, Q2, Q3, Q4 in the first chopping part and the switching tubes Q5, Q6 in the second chopping part The driving signals g5 and g6 can be as shown in Fig. 2-5. FIG. 2-FIG. 5 only enumerate several possible implementation manners, and are not intended to limit the present invention.

Taking the driving signal shown in FIG. 2 as an example, the working process of the bidirectional resonant converter shown in FIG. 1 will be described below.

Before time t0, the switching tubes Q2 and Q3 in the first chopping part are turned on, and the switching tube Q6 in the second chopping part is turned on; at this time, the current path of the bidirectional resonant converter shown in Figure 1 is shown in 6.

At time t0, the switch tube Q2 in the first chopping part and the switch tube Q6 in the second chopping part are turned off, and the switch tube Q3 remains on; after the switch tube Q2 is turned off, the body diode in the switch tube Q2 continues After the switching tube Q6 is turned off, the junction capacitance of the switching tube Q6 is charged, and the junction capacitance of the switching tube Q5 is discharged. After discharging to 0, the current in the second chopping part flows through the body diode of the switching tube Q5, and the voltage Vp commutates; the voltage Vp After the commutation, the current of the body diode of the switch tube Q2 can be reduced rapidly, and after being reduced to 0, the current in the first chopping part flows through the body diode of the switch tube Q1.

At time t1, the switch tube Q5 in the second chopping part is turned on. At this time, the current path of the bidirectional resonant converter shown in FIG. 1 is shown in FIG. The wave part transmits energy to the resonant part, and the resonant part stores energy until t2.

At time t2, the switching tube Q3 in the first chopping part is turned off, the junction capacitance of the switching tube Q3 is charged, the junction capacitance of the switching tube Q4 is discharged, and the current in the first chopping part flows through the body diode of the switching tube Q4 after discharging to 0 .

At time t3, the switching tubes Q1 and Q4 in the first chopping part are turned on. At this time, the current path of the bidirectional resonant converter shown in Fig. 1 is shown in Fig. 8. The resonant part releases energy and transfers energy to the first The second chopping part, until the time t4, so as to realize the boost function.

To sum up, the above-mentioned t0-t4 period is half a cycle of the driving signal of the switching tubes Q5 and Q6 in the second chopping part, and the t0-t1 period is the switching dead period of the switching tubes Q5 and Q6 in the second chopping part. Zone time, t1~t2 period is the energy storage time of the resonant part, t2~t3 period is the dead time for the switching of the switching tubes Q3 and Q4 in the first chopping part, and the t3~t4 period is the resonant part energy release time.

The t4-t8 period is the other half period of the driving signal of the switching tubes Q5 and Q6 in the second chopping part, wherein the t4-t5 period is the dead time for the switching of the switching tubes Q5 and Q6 in the second chopping part , the period t5-t6 is the energy storage time of the resonant part, the period t6-t7 is the dead time for switching the switching tubes Q1 and Q2 in the first chopping part, and the period t7-t8 is the energy release time of the resonant part, the working process is similar, It will not be described in detail here.

In summary, using the control method of the bidirectional resonant converter provided by Embodiment 1 of the present invention, when energy flows in both directions in the bidirectional resonant converter, the gain can be greater than 1, and the reliability and efficiency of the bidirectional resonant converter can be improved.

Example 2:

Based on the same inventive concept, Embodiment 2 of the present invention also provides a control device for a bidirectional resonant converter, the bidirectional resonant converter includes a first chopping part, a resonant part and a second chopping part connected in sequence, the control Devices include:

The first control unit is used to control the output voltage of the resonant part to be a specified voltage Vset within a specified period when the energy in the bidirectional resonant converter is transferred from the second chopping part to the first chopping part; wherein, -Vh< Vset<+Vh, Vh is the output voltage of the first chopping part.

Preferably, the control device also includes:

The second control unit is used to control the switching frequency of the switching tube in the second chopping section to be greater than or equal to the resonance in the resonance section when the energy in the bidirectional resonant converter is transferred from the second chopping section to the first chopping section. The resonant frequency produced by the inductor and the resonant capacitor.

Further, the first control unit is specifically configured to control the output voltage of the resonant part to be a specified voltage Vset within a specified period by controlling the on-off of the switch tube in the first chopping part.

Preferably, the first control unit is specifically configured to, for each switching tube in the second chopping part, control the output voltage of the resonant part from the moment when the switching tube is turned on in each switching period of the switching tube The specified period of time is the specified voltage Vset.

Further, the specified voltage Vset is 0.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (10)

1. A control method for a bidirectional resonant converter, the bidirectional resonant converter comprising a first chopping part, a resonant part and a second chopping part connected in sequence, characterized in that it comprises: When the energy in the bidirectional resonant converter is transferred from the second chopper part to the first chopper part, the output voltage of the resonant part is controlled to be a specified voltage Vset within a specified period; where -Vh <Vset<+Vh, Vh is the output voltage of the first chopping part. 2. The control method according to claim 1, further comprising: When the energy in the bidirectional resonant converter is transferred from the second chopping part to the first chopping part, control the switching frequency of the switching tube in the second chopping part to be greater than or equal to the resonance part The resonant frequency produced by the resonant inductance and resonant capacitor in 3. The control method according to claim 1 or 2, wherein controlling the output voltage of the resonance part to be a specified voltage Vset within a specified period of time specifically includes: By controlling the on-off of the switching tube in the first chopping part, the output voltage of the resonance part is controlled to be a specified voltage Vset within a specified period. 4. The control method according to claim 1 or 2, wherein controlling the output voltage of the resonance part to be a specified voltage Vset within a specified period of time specifically includes: For each switching tube in the second chopping part, in each switching period of the switching tube, the output voltage of the resonance part is controlled to be a specified voltage Vset within a specified period from the moment when the switching tube is turned on. . 5. The control method according to claim 1 or 2, wherein the specified voltage Vset is zero. 6. A control device for a bidirectional resonant converter, the bidirectional resonant converter comprising a first chopping part, a resonant part and a second chopping part connected in sequence, characterized in that it comprises: The first control unit is configured to control the output voltage of the resonant part to be a specified value within a specified period when energy in the bidirectional resonant converter is transferred from the second chopping part to the first chopping part. Voltage Vset; wherein, -Vh<Vset<+Vh, Vh is the output voltage of the first chopping part. 7. The control device according to claim 6, further comprising: A second control unit, configured to control the switch of the switching tube in the second chopping section when the energy in the bidirectional resonant converter is transferred from the second chopping section to the first chopping section The frequency is greater than or equal to the resonant frequency generated by the resonant inductance and resonant capacitor in the resonant part. 8. The control device according to claim 6 or 7, wherein the first control unit is specifically configured to control the resonant part by controlling the on-off of the switching tube in the first chopping part The output voltage of is the specified voltage Vset within a specified period of time. 9. The control device according to claim 6 or 7, characterized in that, the first control unit is specifically configured to, for each switching tube in the second chopping part, in each switching tube of the switching tube In the switching period, the output voltage of the resonant part is controlled to be a specified voltage Vset within a specified period from the moment when the switch is turned on. 10. The control device according to claim 6 or 7, characterized in that the specified voltage Vset is zero.