Zero-voltage turn-off and zero-current turn-on bridge arm circuit and control method

Abstract

The invention discloses a zero-voltage turn-off and zero-current turn-on bridge arm circuit and a control method, and belongs to the field of soft switching circuits. Inductors are led out from the midpoints of four bridge arms of the bridge arm circuit respectively, the midpoint of the first bridge arm is connected with the midpoint of the third bridge arm through one inductor, and the midpoint of the second bridge arm is connected with the midpoint of the fourth bridge arm through one inductor; a capacitor is arranged between the midpoint of the first bridge arm and the midpoint of the second bridge arm, a capacitor is arranged between the midpoint of the third bridge arm and the midpoint of the fourth bridge arm, the current rising rate is delayed through the inductors, the capacitor charging and discharging principle is combined, and on-off time sequence control over all the switching devices is matched, so that zero-current conduction and zero-voltage turn-off of all the switching devices are achieved. The circuit can be applied to all existing bridge arm circuit application scenes, soft switching processing (zero-current conduction and zero-voltage turn-off) can be realized without independently designing an LC resonance circuit, the switching loss is greatly reduced, and the application range is wide.

Description

Technical Field

[0001] The present invention relates to the field of soft switching circuits, and in particular to a zero-voltage turn-off and zero-current turn-on bridge arm circuit and a control method. Background Art

[0002] Soft switching circuits are widely used in switching power supplies, motor drives, power regulation and other fields to reduce the loss and electromagnetic interference (EMI) generated by switching devices. Figure 1 As shown in the figure, in the traditional hard switching circuit, the voltage and current are not zero during the switching process, and there is overlap, resulting in switching loss; and the voltage and current change quickly, and the waveform has obvious overshoot, resulting in switching noise. Figure 2 As shown, the soft switching circuit adds a resonant element to the original circuit, introduces resonance before and after the switching process, eliminates the overlap of voltage and current, and thus reduces switching loss and switching noise.

[0003] Existing soft switching circuits usually use LC resonant circuits to generate resonance at both ends of the switch device, so that the switch device switches when the voltage or current is close to zero, reducing switching losses. Existing soft switching circuits are usually designed and controlled separately for a specific application circuit, that is, a resonant circuit needs to be designed separately for the original topology circuit, which cannot adapt to all scenarios and is not universal. On this basis, how to design a soft switching circuit that does not rely on the LC resonant circuit and can achieve zero voltage shutdown and zero current conduction is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of the prior art and provide a bridge arm circuit with zero voltage shutdown and zero current conduction and a control method.

[0005] The objective of the present invention is achieved through the following technical solutions: a bridge arm circuit with zero voltage shutdown and zero current conduction, the bridge arm circuit is located between the power supply end and the load end, and includes a cascaded first bridge arm, a second bridge arm, a third bridge arm and a fourth bridge arm, the upper bridge arm and the lower bridge arm of the first bridge arm are respectively provided with a first switch device and a second switch device, the upper bridge arm and the lower bridge arm of the second bridge arm are respectively provided with a switch device third switch device and a fourth switch device, the upper bridge arm and the lower bridge arm of the third bridge arm are respectively provided with a fifth switch device and a sixth switch device, the upper bridge arm and the lower bridge arm of the fourth bridge arm are respectively provided with a switch device seventh switch device and an eighth switch device, and the eight switch devices are connected to a control module; the first The midpoint of the bridge arm is connected to the first inductor, the midpoint of the second bridge arm is connected to the second inductor, the first inductor is connected to the second inductor, and a first capacitor is arranged between the midpoint of the first bridge arm and the midpoint of the second bridge arm; the midpoint of the third bridge arm is connected to the third inductor, the midpoint of the fourth bridge arm is connected to the fourth inductor, the third inductor is connected to the fourth inductor, and a second capacitor is arranged between the midpoint of the third bridge arm and the midpoint of the fourth bridge arm; a fifth inductor is arranged between the midpoint of the second bridge arm and the midpoint of the fourth bridge arm, and a sixth inductor is arranged between the midpoint of the first bridge arm and the midpoint of the third bridge arm; a common connection point of the first inductor and the second inductor and a common connection point of the third inductor and the fourth inductor are connected to the energy transfer inductor, and the energy transfer inductor is connected to the power supply end.

[0006] In one example, the switching device is a transistor, which is any one or more of MOSFET, IGBT, BJT, and triode.

[0007] In one example, all switching devices in the bridge arm circuit are IGBTs, the emitter of the first switching device is connected to the collector of the second switching device, the emitter of the third switching device is connected to the collector of the fourth switching device, the emitter of the fifth switching device is connected to the collector of the sixth switching device, and the emitter of the seventh switching device is connected to the collector of the eighth switching device; the collector of the first switching device is connected to the collector of the third switching device, the collector of the third switching device is connected to the collector of the fifth switching device, and the collector of the fifth switching device is connected to the collector of the seventh switching device; the emitter of the second switching device is connected to the emitter of the fourth switching device, the emitter of the fourth switching device is connected to the emitter of the sixth switching device, and the emitter of the sixth switching device is connected to the emitter of the eighth switching device, and the gates of the eight switching devices are all connected to the control module.

[0008] In one example, the bridge arm circuit includes at least two bridge arm circuits formed by any one or more of the above examples. Each single bridge arm circuit can be cascaded, parallel or mixedly connected, and each bridge arm circuit acts as an independent module to realize single bridge arm control in the switching power supply topology.

[0009] It should be further explained that the technical features corresponding to the above examples can be combined or replaced with each other to form a new technical solution.

[0010] The present invention also includes a method for controlling a bridge arm circuit with zero voltage shutdown and zero current conduction, the method is used to control the bridge arm circuit formed by any one of the above examples or a combination of multiple examples, the method execution body is a control module, and includes the following steps:

[0011] Controlling the switching timing of the switch devices in each bridge arm to charge and discharge the first capacitor and the second capacitor, and turning off the switch devices on the zero voltage side of the first capacitor and the second capacitor through the charging and discharging process of the first capacitor and the second capacitor to achieve zero voltage shutdown;

[0012] Control the switching timing of the switching devices in each bridge arm, adjust the current changes on the first inductor, the second inductor, the third inductor, the fourth inductor, the fifth inductor, and the sixth inductor, delay the rising speed of the current on the corresponding inductor, turn on the switching device at zero current, and achieve zero current conduction.

[0013] In one example, zero voltage shutdown includes:

[0014] During the positive half cycle of AC power:

[0015] When the third switch device, the second switch device, the fifth switch device, and the eighth switch device are turned off, and the first switch device, the fourth switch device, the seventh switch device, and the sixth switch device are turned on, the voltage at the midpoint of the second bridge arm and the midpoint of the third bridge arm is zero, and the fourth switch device and the sixth switch device are turned off, and the voltage at one end of the first capacitor close to the midpoint of the second bridge arm and the voltage at one end of the second capacitor close to the midpoint of the third bridge arm rise, so that the fourth switch device and the sixth switch device are turned off at zero voltage;

[0016] When the first switch device, the fourth switch device, the seventh switch device, and the sixth switch device are turned off, and the third switch device, the second switch device, the fifth switch device, and the eighth switch device are turned on, the voltage at the midpoint of the first bridge arm and the midpoint of the fourth bridge arm is zero, the second switch device and the eighth switch device are turned off, and the voltage at one end of the first capacitor close to the midpoint of the first bridge arm and the voltage at one end of the second capacitor close to the midpoint of the fourth bridge arm rise, so that the second switch device and the eighth switch device are turned off at zero voltage;

[0017] During the negative half cycle of AC power:

[0018] When the first switch device, the fourth switch device, the seventh switch device, and the sixth switch device are turned off, and the second switch device, the third switch device, the eighth switch device, and the fifth switch device are turned on, the voltage at the midpoint of the second bridge arm and the midpoint of the third bridge arm is zero, the third switch device and the fifth switch device are turned off to achieve zero voltage shutdown of the third switch device and the fifth switch device, and the voltage at one end of the first capacitor close to the midpoint of the second bridge arm and one end of the second capacitor close to the midpoint of the third bridge arm rises;

[0019] When the second switch device, the third switch device, the fifth switch device, and the eighth switch device are turned off, and the first switch device, the fourth switch device, the seventh switch device, and the sixth switch device are turned on, the voltage at the midpoint of the first bridge arm and the midpoint of the fourth bridge arm is zero, and the first switch device and the seventh switch device are turned off at zero voltage, and the voltage at one end of the first capacitor close to the midpoint of the first bridge arm and the voltage at one end of the second capacitor close to the midpoint of the fourth bridge arm rise.

[0020] Zero current conduction includes:

[0021] In the positive half cycle of the AC power supply, when the first switch device, the third switch device, the fifth switch device, and the seventh switch device are initially in the off state:

[0022] When the second switch device and the sixth switch device are turned off and the fourth switch device and the eighth switch device are turned on, the current on the first inductor and the fourth inductor is zero, the fourth switch device and the eighth switch device are turned off, the current on the second inductor and the third inductor flows through the diodes on the third switch device and the seventh switch device, the first switch device and the fifth switch device are turned on, and the zero current conduction of the first switch device and the fifth switch device is realized;

[0023] When the fourth switch device and the eighth switch device are turned off and the second switch device and the sixth switch device are turned on, the current on the second inductor and the third inductor is zero, the second switch device and the sixth switch device are turned off, the current on the first inductor and the fourth inductor flows through the diodes on the first switch device and the fifth switch device, the third switch device and the seventh switch device are turned on, and the third switch device and the seventh switch device are turned on at zero current;

[0024] In the negative half cycle of the AC power supply, when the second switch device, the fourth switch device, the sixth switch device, and the eighth switch device are in the off state in the initial state:

[0025] When the first switch device and the fifth switch device are turned off, and the third switch device and the seventh switch device are turned on, the current on the second inductor and the third inductor is zero, the third switch device and the seventh switch device are turned off, the current on the first inductor and the fourth inductor flows through the diodes on the fourth switch device and the eighth switch device, the second switch device and the sixth switch device are turned on, and the second switch device and the sixth switch device are turned on with zero current, the current flowing through the fourth switch device through the first inductor is zero, and the current flowing through the eighth switch device through the fourth inductor is zero;

[0026] When the third switch device and the seventh switch device are turned off and the first switch device and the fifth switch device are turned on, the current flowing through the fourth switch device through the first inductor is zero and the current flowing through the eighth switch device through the fourth inductor is zero, the third switch device and the seventh switch device are turned off, the current on the second inductor and the third inductor flows through the second switch device and the sixth switch device, and the fourth switch device and the eighth switch device are turned on, thereby achieving zero current conduction of the fourth switch device and the eighth switch.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention leads out inductors at the midpoints of the four bridge arms, designs inductors and capacitors between the bridge arms, delays the current rising rate by the inductors, combines the capacitor charging and discharging principle, and cooperates with the on-off timing control of each switching device to achieve zero current conduction and zero voltage shutdown of each switching device. The present invention can be applied to all existing bridge arm circuit application scenarios, and can achieve soft switching processing (zero current conduction and zero voltage shutdown) without the need to design an LC resonant circuit separately, thereby greatly reducing switching losses and having a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings. The accompanying drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The same reference numerals are used in these drawings to represent the same or similar parts. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0030] Figure 1 It is a curve diagram of voltage and current during the switching process of the existing hard switching circuit;

[0031] Figure 2 The voltage and current curves during the switching process of the soft switching circuit with the added resonant element;

[0032] Figure 3 A schematic diagram of a bridge arm circuit for zero voltage shutdown and zero current conduction provided as an example of the present invention. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be noted that the directions or positional relationships indicated by "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are directions or positional relationships based on the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the use of ordinal numbers (e.g., "first and second", "first to fourth", etc.) is to distinguish objects, and is not limited to this order, and cannot be understood as indicating or implying relative importance.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] In one example, a bridge arm circuit with zero voltage shutdown and zero current conduction is provided between the power supply end and the load end, including a cascaded first bridge arm, a second bridge arm, a third bridge arm and a fourth bridge arm, the fourth bridge arm is connected to the load end, and optionally, the fourth bridge arm is connected to the load end via a voltage transformation processing circuit, such as the second bridge arm is connected to the load end via a boost circuit. The upper bridge arm and the lower bridge arm of the first bridge arm are respectively provided with a first switch device Q1 and a second switch device Q2, the upper bridge arm and the lower bridge arm of the second bridge arm are respectively provided with a switch device third switch device Q3 and a fourth switch device Q4, the upper bridge arm and the lower bridge arm of the third bridge arm are respectively provided with a fifth switch device Q5 and a sixth switch device Q6, the upper bridge arm and the lower bridge arm of the fourth bridge arm are respectively provided with a switch device seventh switch device Q7 and an eighth switch device Q8, and Q1-Q8 are connected to a control module. The switch device is a transistor, such as any one or more of MOSFET, IGBT, BJT, triode, etc. A diode can be set between the source and drain of the transistor or between the emitter and collector of the transistor. Of course, if the emitter and collector of the transistor are already integrated with diodes, no new diode needs to be integrated.

[0038] Optionally, all the switch devices in the bridge arm circuit are IGBTs, and a diode is integrated between the emitter and collector of the IGBT, the anode of the diode is connected to the emitter, and the cathode of the diode is connected to the collector. Specifically, Figure 3 As shown, the emitter of Q1 is connected to the collector of Q2, the emitter of Q3 is connected to the collector of Q4, the emitter of Q5 is connected to the collector of Q6, and the emitter of Q7 is connected to the collector of Q8; the collector of Q1 is connected to the collector of Q3, the collector of Q3 is connected to the collector of Q5, and the collector of Q5 is connected to the collector of Q7; the emitter of Q2 is connected to the emitter of Q4, the emitter of Q4 is connected to the emitter of Q6, and the emitter of Q6 is connected to the emitter of Q8, and the gates of Q1-Q8 are all connected to the control module (not shown in the figure).

[0039] Furthermore, the midpoint of the first bridge arm is connected to the first inductor L1, the midpoint of the second bridge arm is connected to the second inductor L2, the first inductor L1 is connected to the second inductor L2, and a first capacitor C1 is provided between the midpoint of the first bridge arm and the midpoint of the second bridge arm; the midpoint of the third bridge arm is connected to the third inductor L3, the midpoint of the fourth bridge arm is connected to the fourth inductor L4, the third inductor L3 is connected to the fourth inductor L4, and a second capacitor C2 is provided between the midpoint of the third bridge arm and the midpoint of the fourth bridge arm. At this time, the connection point between the first capacitor C1 and the midpoint of the first bridge arm is defined as B1, the connection point between the first capacitor C1 and the midpoint of the second bridge arm is defined as B2, the end of the first capacitor C1 close to B1 is defined as end 1 of the first capacitor C1, and the end of the first capacitor C1 close to B2 is defined as end 2 of the first capacitor C1; the connection point between the second capacitor C2 and the midpoint of the third bridge arm is defined as B3, the connection point between the second capacitor C1 and the midpoint of the fourth bridge arm is defined as B4, the end of the second capacitor C2 close to B1 is defined as end 1 of the second capacitor C2, and the end of the second capacitor close to B2 is defined as end 2 of the second capacitor C2.

[0040] Furthermore, a fifth inductor L5 is provided between the midpoint of the second bridge arm and the midpoint of the fourth bridge arm, and a sixth inductor L6 is provided between the midpoint of the first bridge arm and the midpoint of the third bridge arm; a common connection point of the first inductor L1 and the second inductor L2, and a common connection point of the third inductor L3 and the fourth inductor L4 are connected to the energy transfer inductor L, and the energy transfer inductor is connected to the positive pole of the power supply.

[0041] For zero voltage shutdown, the switch devices on the zero voltage side of the capacitors C1 and C2 are turned off by charging and discharging the capacitors C1 and C2, thereby achieving zero voltage shutdown. The working principle of the bridge arm circuit of the present invention is as follows:

[0042] In the positive half cycle of the AC power supply, when Q3, Q2, Q5, Q8 are turned off and Q1, Q4, Q7, Q6 are turned on, the voltage at B1, B4 is Vdc (the DC voltage obtained after the bridge arm circuit processing), and the voltage at B2, B3 is 0. At this time, Q4, Q6 are turned off, and the 2 ends of capacitor C1 and the 1 end of C2 will slowly rise to Vdc, and Q4, Q6 are turned off with zero voltage. Similarly, when Q1, Q4, Q7, Q6 are turned off and Q3, Q2, Q5, Q8 are turned on, the voltage at B2, B3 is Vdc, and the voltage at B1, B4 is 0. At this time, Q2, Q8 are turned off, and the 1 end of capacitor C1 and the 2 ends of C2 will slowly rise to Vdc, and Q2, Q8 are turned off with zero voltage.

[0043] In the negative half cycle of the AC power supply, when Q1, Q4, Q7, and Q6 are turned off and Q2, Q3, Q8, and Q5 are turned on, the voltage at B2 and B3 is zero, Q3 and Q5 are turned off, and capacitors C1 and C2 begin to charge, achieving zero voltage shutdown of Q3 and Q5, and the voltage at terminals 2 of capacitor C1 and 1 of capacitor C2 rises; when Q2, Q3, Q5, and Q8 are turned off and Q1, Q4, Q7, and Q6 are turned on, the voltage at B1 and B4 is zero, Q1 and Q7 are turned off, achieving zero voltage shutdown of Q1 and Q7, and the voltage at terminals 1 of capacitor C1 and 2 of capacitor C2 rises.

[0044] For zero current conduction, the current rise speed is slowed down by inductors L1-L6, and the switch device at zero current is turned on, thereby achieving zero current conduction. The working principle of the bridge arm circuit of the present invention is as follows:

[0045] In the positive half cycle of the AC power supply, when Q1, Q3, Q5, and Q7 are initially in the off state:

[0046] When Q2 and Q6 are turned off and Q4 and Q8 are turned on, the current on L1 and L4 is 0, then I1=0 (I1 is the current on inductor L1), I5=0 (I5 is the current flowing to Q5 through inductor L4), at this time Q4 and Q8 are turned off, the current on L2 and L3 flows through the diodes on Q3 and Q7, at this time Q1 and Q5 are turned on, I1 and I5 rise slowly, Q1 and Q5 are turned on with zero current, and the current I4 (the current flowing to Q4 through inductor L2) and I8 (the current flowing to Q8 through inductor L3) on L2 and L3 will gradually be pulled to 0. Similarly, when Q4 and Q8 are turned off and Q2 and Q6 are turned on, the current on L2 and L3 is 0, then I3=0 (I3 is the current flowing to Q3 through L2), I7=0 (I7 is the current flowing to Q7 through L3). At this time, Q2 and Q6 are turned off, and the current on L1 and L4 flows through the diodes on Q1 and Q5. At this time, Q3 and Q7 are turned on, and I3 and I7 rise slowly. Q3 and Q7 are turned on with zero current, and the current I2 (the current flowing to Q2 through the inductor L1) and I6 (the current flowing to Q6 through L4) on L1 and L4 will gradually be pulled to 0.

[0047] In the negative half cycle of the AC power supply, when Q2, Q4, Q6, and Q8 are initially in the off state:

[0048] When Q1 and Q5 are turned off and Q3 and Q7 are turned on, the current on L2 and L3 is zero. Q3 and Q7 are turned off, and the current on L1 and L4 flows through the diodes on Q4 and Q8. Q2 and Q6 are turned on to achieve zero current conduction of Q2 and Q6, and the current flowing through Q4 through L1 is pulled to zero, and the current flowing through Q8 through L4 is pulled to 0; when Q3 and Q7 are turned off and Q1 and Q5 are turned on, the current flowing through Q4 through L1 is gradually pulled to 0, and the current flowing through Q8 through L4 is gradually pulled to 0, Q3 and Q7 are turned off, and the current on L2 and L3 flows through Q2 and Q6, Q4 and Q8 are turned on to achieve zero current conduction of Q4 and Q8. At this time, the current flowing through Q2 through L2 and the current flowing through Q6 through L3 will gradually be pulled to 0.

[0049] In one example, a bridge arm circuit unit with zero voltage shutdown and zero current conduction includes multiple bridge arm circuits described in any one or more of the above examples, and the bridge arm circuits are cascaded, that is, the last bridge arm of the previous level bridge arm circuit is cascaded with the first bridge arm of the next level bridge arm circuit to form a multi-level conversion circuit.

[0050] The present invention also includes a control method for a bridge arm circuit with zero voltage shutdown and zero current conduction, which is used to control a circuit formed by any one of the above examples or a combination of multiple examples. The method execution body is a control module, and for zero voltage shutdown, the method includes the following steps:

[0051] In the positive half cycle of the AC power supply, when Q3, Q2, Q5, and Q8 are turned off and Q1, Q4, Q7, and Q6 are turned on, the voltage at B2 and B3 is 0, and when Q4 and Q6 are turned off, the voltage at the two ends of capacitor C1 and the one end of C2 rises slowly (from 0 to Vdc), that is, when Q4 and Q6 are turned off, it is a zero voltage shutdown; when Q1, Q4, Q7, and Q6 are turned off and Q3, Q2, Q5, and Q8 are turned on, the voltage at B1 and B4 is 0, and when Q2 and Q8 are turned off, the voltage at the one end of capacitor C1 and the two ends of C2 rises slowly (from 0 to Vdc), that is, when Q2 and Q8 are turned off, it is a zero voltage shutdown.

[0052] In the negative half cycle of the AC power supply, when Q1, Q4, Q7, and Q6 are turned off and Q2, Q3, Q8, and Q5 are turned on, the voltage at B2 and B3 is zero, Q3 and Q5 are turned off, and capacitors C1 and C2 begin to charge, achieving zero voltage shutdown of Q3 and Q5, and the voltage at terminals 2 of capacitor C1 and 1 of capacitor C2 rises; when Q2, Q3, Q5, and Q8 are turned off and Q1, Q4, Q7, and Q6 are turned on, the voltage at B1 and B4 is zero, Q1 and Q7 are turned off, achieving zero voltage shutdown of Q1 and Q7, and the voltage at terminals 1 of capacitor C1 and 2 of capacitor C2 rises.

[0053] For zero current conduction, the following steps are included:

[0054] In the positive half cycle of the AC power supply, when Q1, Q3, Q5, and Q7 are initially in the off state:

[0055] When Q2 and Q6 are turned off and Q4 and Q8 are turned on, the current on L1 and L4 is 0, so I1=0 and I5=0. Q4 and Q8 are turned off, and the current on L2 and L3 flows through the diodes on Q3 and Q7. Q1 and Q5 are turned on, and I1 and I5 rise slowly (starting from zero current and rising slowly). When Q1 and Q5 are turned on, no current flows to Q1 and Q5 instantly, achieving zero current conduction of Q1 and Q5.

[0056] When Q4 and Q8 are turned off and Q2 and Q6 are turned on, the current on L2 and L3 is 0, then I3=0 and I7=0. Q2 and Q6 are turned off, and the current on L1 and L4 flows through the diodes on Q1 and Q5. Q3 and Q7 are turned on, and I3 and I7 rise slowly (starting from zero current and rising slowly). When Q3 and Q7 are turned on, no current flows to Q3 and Q7 instantly, thus achieving zero current conduction of Q3 and Q7.

[0057] In the negative half cycle of the AC power supply, when Q2, Q4, Q6, and Q8 are initially in the off state:

[0058] When Q1 and Q5 are turned off and Q3 and Q7 are turned on, the current on L2 and L3 is zero. When Q3 and Q7 are turned off, the current on L1 and L4 flows through the diodes on Q4 and Q8, turning on Q2 and Q6 to achieve zero current conduction of Q2 and Q6. The current flowing through Q4 via L1 is pulled to zero, and the current flowing through Q8 via L4 is pulled to 0.

[0059] When Q3 and Q7 are turned off and Q1 and Q5 are turned on, the current flowing through Q4 through L1 is gradually pulled to 0, and the current flowing through Q8 through L4 is gradually pulled to 0. Q3 and Q7 are turned off, and the current on L2 and L3 flows through Q2 and Q6, turning on Q4 and Q8 to achieve zero current conduction of Q4 and Q8. At this time, the current flowing through Q2 through L2 and the current flowing through Q6 through L3 will gradually be pulled to 0.

[0060] The above specific implementation methods are detailed descriptions of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A bridge arm circuit with zero voltage shutdown and zero current conduction, the bridge arm circuit is located between the power supply end and the load end, and includes a cascaded first bridge arm, a second bridge arm, a third bridge arm and a fourth bridge arm, the upper bridge arm and the lower bridge arm of the first bridge arm are respectively provided with a first switch device and a second switch device, the upper bridge arm and the lower bridge arm of the second bridge arm are respectively provided with a switch device, a third switch device and a fourth switch device, the upper bridge arm and the lower bridge arm of the third bridge arm are respectively provided with a fifth switch device and a sixth switch device, the upper bridge arm and the lower bridge arm of the fourth bridge arm are respectively provided with a switch device, a seventh switch device and an eighth switch device, and the eight switch devices are connected to a control module, characterized in that: The midpoint of the first bridge arm is connected to the first inductor, the midpoint of the second bridge arm is connected to the second inductor, the first inductor is connected to the second inductor, and a first capacitor is arranged between the midpoint of the first bridge arm and the midpoint of the second bridge arm; the midpoint of the third bridge arm is connected to the third inductor, the midpoint of the fourth bridge arm is connected to the fourth inductor, the third inductor is connected to the fourth inductor, and a second capacitor is arranged between the midpoint of the third bridge arm and the midpoint of the fourth bridge arm; a fifth inductor is arranged between the midpoint of the second bridge arm and the midpoint of the fourth bridge arm, and a sixth inductor is arranged between the midpoint of the first bridge arm and the midpoint of the third bridge arm; a common connection point of the first inductor and the second inductor and a common connection point of the third inductor and the fourth inductor are connected to the energy transfer inductor, and the energy transfer inductor is connected to the power supply end.

2. A zero voltage shutdown and zero current conduction bridge arm circuit according to claim 1, characterized in that: The switching device is a transistor, which can be any one or more of MOSFET, IGBT, BJT and triode.

3. The bridge arm circuit with zero voltage shutdown and zero current conduction according to claim 1, characterized in that: All switching devices in the bridge arm circuit are IGBTs, the emitter of the first switching device is connected to the collector of the second switching device, the emitter of the third switching device is connected to the collector of the fourth switching device, the emitter of the fifth switching device is connected to the collector of the sixth switching device, and the emitter of the seventh switching device is connected to the collector of the eighth switching device; the collector of the first switching device is connected to the collector of the third switching device, the collector of the third switching device is connected to the collector of the fifth switching device, and the collector of the fifth switching device is connected to the collector of the seventh switching device; the emitter of the second switching device is connected to the emitter of the fourth switching device, the emitter of the fourth switching device is connected to the emitter of the sixth switching device, and the emitter of the sixth switching device is connected to the emitter of the eighth switching device, and the gates of the eight switching devices are all connected to the control module.

4. The bridge arm circuit with zero voltage shutdown and zero current conduction according to claim 1, characterized in that: Comprising at least two bridge arm circuits as described in any one of claims 1-3.

5. A control method for a bridge arm circuit with zero voltage shutdown and zero current conduction, characterized in that: The method execution body is a control module, which is used to control the bridge arm circuit according to any one of claims 1 to 4, and includes the following steps: Controlling the switching timing of the switch devices in each bridge arm to charge and discharge the first capacitor and the second capacitor, and turning off the switch devices on the zero voltage side of the first capacitor and the second capacitor through the charging and discharging process of the first capacitor and the second capacitor to achieve zero voltage shutdown; Control the switching timing of the switching devices in each bridge arm, adjust the current changes on the first inductor, the second inductor, the third inductor, the fourth inductor, the fifth inductor, and the sixth inductor, delay the rising speed of the current on the corresponding inductor, turn on the switching device at zero current, and achieve zero current conduction.

6. The control method of the bridge arm circuit with zero voltage shutdown and zero current conduction according to claim 5, characterized in that: Zero voltage shutdown includes: During the positive half cycle of AC power: When the third switch device, the second switch device, the fifth switch device, and the eighth switch device are turned off, and the first switch device, the fourth switch device, the seventh switch device, and the sixth switch device are turned on, the voltage at the midpoint of the second bridge arm and the midpoint of the third bridge arm is zero, and the fourth switch device and the sixth switch device are turned off, and the voltage at one end of the first capacitor close to the midpoint of the second bridge arm and the voltage at one end of the second capacitor close to the midpoint of the third bridge arm rise, so that the fourth switch device and the sixth switch device are turned off at zero voltage; When the first switch device, the fourth switch device, the seventh switch device, and the sixth switch device are turned off, and the third switch device, the second switch device, the fifth switch device, and the eighth switch device are turned on, the voltage at the midpoint of the first bridge arm and the midpoint of the fourth bridge arm is zero, the second switch device and the eighth switch device are turned off, and the voltage at one end of the first capacitor close to the midpoint of the first bridge arm and the voltage at one end of the second capacitor close to the midpoint of the fourth bridge arm rise, so that the second switch device and the eighth switch device are turned off at zero voltage; During the negative half cycle of AC power: When the first switch device, the fourth switch device, the seventh switch device, and the sixth switch device are turned off, and the second switch device, the third switch device, the eighth switch device, and the fifth switch device are turned on, the voltage at the midpoint of the second bridge arm and the midpoint of the third bridge arm is zero, the third switch device and the fifth switch device are turned off to achieve zero voltage shutdown of the third switch device and the fifth switch device, and the voltage at one end of the first capacitor close to the midpoint of the second bridge arm and one end of the second capacitor close to the midpoint of the third bridge arm rises; When the second switch device, the third switch device, the fifth switch device, and the eighth switch device are turned off, and the first switch device, the fourth switch device, the seventh switch device, and the sixth switch device are turned on, the voltage at the midpoint of the first bridge arm and the midpoint of the fourth bridge arm is zero, and the first switch device and the seventh switch device are turned off at zero voltage, and the voltage at one end of the first capacitor close to the midpoint of the first bridge arm and the voltage at one end of the second capacitor close to the midpoint of the fourth bridge arm rise. Zero current conduction includes: In the positive half cycle of the AC power supply, when the first switch device, the third switch device, the fifth switch device, and the seventh switch device are initially in the off state: When the second switch device and the sixth switch device are turned off and the fourth switch device and the eighth switch device are turned on, the current on the first inductor and the fourth inductor is zero, the fourth switch device and the eighth switch device are turned off, the current on the second inductor and the third inductor flows through the diodes on the third switch device and the seventh switch device, the first switch device and the fifth switch device are turned on, and the zero current conduction of the first switch device and the fifth switch device is realized; When the fourth switch device and the eighth switch device are turned off and the second switch device and the sixth switch device are turned on, the current on the second inductor and the third inductor is zero, the second switch device and the sixth switch device are turned off, the current on the first inductor and the fourth inductor flows through the diodes on the first switch device and the fifth switch device, the third switch device and the seventh switch device are turned on, and the third switch device and the seventh switch device are turned on at zero current; In the negative half cycle of the AC power supply, when the second switch device, the fourth switch device, the sixth switch device, and the eighth switch device are in the off state in the initial state: When the first switch device and the fifth switch device are turned off, and the third switch device and the seventh switch device are turned on, the current on the second inductor and the third inductor is zero, the third switch device and the seventh switch device are turned off, the current on the first inductor and the fourth inductor flows through the diodes on the fourth switch device and the eighth switch device, the second switch device and the sixth switch device are turned on, and the second switch device and the sixth switch device are turned on with zero current, the current flowing through the fourth switch device through the first inductor is zero, and the current flowing through the eighth switch device through the fourth inductor is zero; When the third switch device and the seventh switch device are turned off and the first switch device and the fifth switch device are turned on, the current flowing through the fourth switch device through the first inductor is zero and the current flowing through the eighth switch device through the fourth inductor is zero, the third switch device and the seventh switch device are turned off, the current on the second inductor and the third inductor flows through the second switch device and the sixth switch device, and the fourth switch device and the eighth switch device are turned on, thereby achieving zero current conduction of the fourth switch device and the eighth switch.

Images