No-dead-zone bridge circuit and magnetic suspension system circuit

Abstract

The invention discloses a dead-zone-free bridge circuit which comprises a power supply positive electrode, a power supply negative electrode and at least one bridge arm circuit, the bridge arm circuit comprises a first switching device, a second switching device and at least one direct connection prevention inductor, and the first end of the first switching device is electrically connected with the power supply positive electrode; the at least one direct connection prevention inductor is connected in series between the second end of the first switching device and the first end of the second switching device, the second end of the second switching device is electrically connected with the negative electrode of the power supply, and the third end of the first switching device and the third end of the second switching device are control ends; the output end of the bridge arm circuit is electrically connected between the at least one shoot-through prevention inductor and the first end of the second switching device or between the at least one shoot-through prevention inductor and the second end of the first switching device or between the at least one shoot-through prevention inductor. According to the bridge circuit, dead time does not need to be set, the direct connection protection effect of the bridge arm switching device can be achieved, and the output of the bridge circuit is hardly influenced.

Description

Technical Field

[0001] The invention relates to the field of magnetic suspension technology, in particular to a dead zone-free bridge circuit which can be applied to a power amplifier circuit or a sensor detection circuit in a magnetic suspension system. Background Art

[0002] A magnetic levitation motor is a magnetic levitation rotary drive that uses magnetic field force to suspend the rotor so that there is no mechanical contact between the rotor and the stator. The magnetic levitation motor can be a magnetic bearing motor, a bearingless motor, or a bearingless thin-film motor, etc.

[0003] A magnetic bearing motor, also known as a magnetic bearing, is a motor that combines a rotary drive motor with an axial magnetic bearing or / and a radial magnetic bearing or / and an axial-diameter hybrid magnetic bearing instead of integrating them together.

[0004] A bearingless motor is a motor that integrates motor rotation and suspension functions. A bearingless motor has an additional set of windings on top of the windings that generate a rotating drive magnetic field to generate an excitation magnetic field. The interaction between the two magnetic fields breaks the balanced distribution of the original drive magnetic field, thereby generating a radial force acting on the rotor. The rotor is suspended by controlling the radial force in the motor. Compared with a magnetic bearing motor, the magnetic suspension winding of a bearingless motor is wound on the stator and does not occupy additional radial space, which to a certain extent overcomes the shortcomings of large size and high cost of magnetic bearings. In order to achieve suspension of the motor rotor in five degrees of freedom, early bearingless motors generally required two bearingless motors and one axial magnetic bearing.

[0005] The bearingless thin-film motor is a special bearingless motor that inherits the advantages of bearingless motors. The axial length to diameter ratio of the rotor is very small and it is in the shape of a thin film, eliminating the axial magnetic bearing. The bearingless technology is used to realize the rotation of the rotor and the active suspension in the radial direction. The magnetic circuit formed by the mechanical structure is used to realize the passive suspension of the other three degrees of freedom except the radial and rotor rotation degrees of freedom. It has the characteristics of high cleanliness, no precipitation, no particles, no dynamic seal, and excellent performance. It has good application prospects in ultra-pure drive fields such as biochemistry, medical treatment, and semiconductor manufacturing.

[0006] Unless otherwise specified, the term magnetic levitation motor refers to a magnetic levitation rotary drive that uses magnetic field force to suspend the rotor so that there is no mechanical contact between the rotor and the stator.

[0007] The magnetic levitation motor can be assembled with fitting parts of different functions, thus becoming a magnetic levitation device for different application requirements. In one embodiment, the magnetic levitation device can be configured as a magnetic levitation pump. In the application of the magnetic levitation pump, the magnetic levitation pump includes a magnetic levitation motor and a pump head. The pump head includes a pump casing and a rotor impeller disposed within the pump casing. The magnetic levitation rotor is both the rotor of the magnetic levitation motor and a part of the rotor impeller of the pump, and can be, for example, a permanent magnet rotor, a short-circuit cage rotor, or a reluctance rotor. The magnetic levitation stator is configured to drive the rotor impeller to rotate and levitate; in another embodiment, the magnetic levitation device is configured as a magnetic levitation mixer. In the application of the magnetic levitation mixer, the magnetic levitation mixer includes a magnetic levitation motor and a mixing device. The mixing device includes a mixing container and a rotor mixing head disposed within the mixing container. The magnetic levitation rotor is both the rotor of the magnetic levitation motor and a part of the rotor mixing head of the mixing device. The magnetic levitation stator is configured to drive the rotor mixing head to rotate and levitate. In still another embodiment, the magnetic levitation device can also be configured as a magnetic levitation turntable. The magnetic levitation turntable includes a magnetic levitation motor and a rotor support platform. The rotor support platform includes a tabletop and a magnetic levitation rotor. The tabletop and the magnetic levitation rotor form an integral rotor. The magnetic levitation stator is configured to drive the rotor support platform to rotate and levitate.

[0008] Compared with a traditional motor using a contact mechanical bearing, the magnetic levitation motor needs to perform more degrees of freedom control. This requires the use of more sensors. Various sensors and sensor circuits are collectively referred to as the sensor assembly herein. Various conditioning circuits for conditioning and processing the sensor signals containing control data output by the sensor assembly are collectively referred to as the signal conditioning module herein. The sensor assembly and the signal conditioning module constitute a sensor system. Through the sensor system, the control data of the magnetic levitation motor can be detected in real time. The control data can include, for example, rotor displacement data, rotor angle data (rotor speed data), or current data of the electromagnetic coil, etc. Taking the control data as the feedback quantity, the control host or controller of the magnetic levitation motor generates a control signal for the power amplifier as the execution part according to the control strategy. The power amplifier outputs to excite the electromagnetic coils of the stator part of the magnetic levitation motor to achieve the suspension and / or rotation control of the rotor. The power amplifier is also called a power amplification circuit. For example, a PWM power amplifier. The power amplifier can be an output stage or output stage circuit including a PWM generator or a PWM circuit, or can be merely an output stage or output stage circuit for power amplification. Herein, various power amplifiers including the output stage or output stage circuit are collectively referred to as the power amplification system.

[0009] At present, in the power amplification system, sensor system, and power supply system of the magnetic levitation system, a half-bridge drive circuit or a full-bridge drive circuit composed of switching devices is indispensable. For example, the power amplification system includes a power amplification circuit for driving the electromagnetic winding, the drive circuit for driving the sensor coil in the sensor system, and the inverter circuit or rectifier circuit in the power supply system, etc. Taking the power amplification system of a single-winding bearingless motor as an example, refer to Figure 1 , the power amplification circuit is used to drive six electromagnetic windings (W1-W6) to generate electromagnetic torque and levitation force, so as to drive the magnetic levitation stator to rotate and levitate stably. Among them, the power amplification circuit includes six power module units corresponding to each electromagnetic winding, and each power module unit can be a full-bridge drive circuit (H-bridge circuit) or a half-bridge drive circuit. The full-bridge drive circuit (two bridge arm circuits) or the half-bridge drive circuit often sets a dead time to avoid shoot-through of the same bridge arm. For example, the dead time should be greater than or equal to the maximum value of the turn-on and turn-off times of the bridge arm switching devices (transistors, thyristors, MOSFETs, or IGBTs, etc.) to prevent short circuits caused by shoot-through of the upper and lower bridge arms and avoid burning out of the PN junctions of the switching devices due to excessive current. However, setting the dead time will cause distortion of the output waveform, increase in low-order harmonics, and loss of fundamental wave voltage. Moreover, as the output frequency increases, the influence of the dead time on the waveform becomes more and more serious, which is a greater challenge for the magnetic levitation system of precision motion control. And there is no control current during the dead time, and the magnetic levitation rotor will be out of control during the dead time, affecting the stable operation of the magnetic levitation rotor. Therefore, how to solve the influence of the dead time on the power amplification system, sensor system, and power supply system of the magnetic levitation system has become an urgent technical problem to be solved. Summary of the Invention

[0010] In order to overcome the defects in the prior art, an embodiment of the present invention provides a dead-time-free bridge circuit and a magnetic levitation system circuit, which are used to solve at least one of the above problems.

[0011] An embodiment of the present disclosure discloses a dead-time-free bridge circuit, including a power supply positive electrode, a power supply negative electrode, and at least one bridge arm circuit provided between the power supply positive electrode and the power supply negative electrode. The bridge arm circuit includes a first switching device, a second switching device, and at least one anti-shoot-through inductor. The first end of the first switching device is electrically connected to the power supply positive electrode, the at least one anti-shoot-through inductor is connected in series between the second end of the first switching device and the first end of the second switching device, the second end of the second switching device is electrically connected to the power supply negative electrode, the third ends of the first switching device and the second switching device are both control ends, and the output end of the bridge arm circuit is electrically connected between the at least one anti-shoot-through inductor and the first end of the second switching device, or between the at least one anti-shoot-through inductor and the second end of the first switching device, or between the at least one anti-shoot-through inductors.

[0012] Further, the number of the at least one DC-blocking inductor is configured to be one, denoted as the DC-blocking inductor, and the output end of the bridge arm circuit is electrically connected between the DC-blocking inductor and the first end of the second switching device or between the DC-blocking inductor and the second end of the first switching device.

[0013] Further, the number of the at least one DC-blocking inductor is configured to be two, denoted as the first DC-blocking inductor and the second DC-blocking inductor, and the output end of the bridge arm circuit is electrically connected to the line between the first DC-blocking inductor and the second DC-blocking inductor.

[0014] Further, the bridge arm circuit further includes a first freewheeling diode, a second freewheeling diode, a third freewheeling diode, and a fourth freewheeling diode. The first freewheeling diode is connected in parallel between the first end of the first switching device and the line. The third freewheeling diode is connected in parallel between the second end of the first switching device and the line. The second freewheeling diode is connected in parallel between the second end of the second switching device and the line. The fourth freewheeling diode is connected in parallel between the first end of the second switching device and the line. Alternatively, the first freewheeling diode is connected in parallel between the first end and the second end of the first switching device, the third freewheeling diode is connected in parallel between the second end of the first switching device and the line, and the positive terminal of the first freewheeling diode is serially connected to the negative terminal of the third freewheeling diode. The second freewheeling diode is connected in parallel between the first end and the second end of the second switching device, the fourth freewheeling diode is connected in parallel between the first end of the second switching device and the line, and the positive terminal of the fourth freewheeling diode is serially connected to the negative terminal of the second freewheeling diode.

[0015] Further, the bridge circuit further includes a bootstrap circuit. The bootstrap circuit includes a bootstrap diode, a bootstrap capacitor, and a driving chip. The anode of the bootstrap diode is electrically connected to the power supply. The cathode of the bootstrap diode is electrically connected to the first end of the bootstrap capacitor. The second end of the bootstrap capacitor is electrically connected to the line between the second end of the first switching device and the first DC-blocking inductor, and the second end of the bootstrap capacitor is electrically connected to the VS pin of the driving chip. The H0 pin of the driving chip is electrically connected to the third end of the first switching device of the bridge arm circuit. The L0 pin of the driving chip is electrically connected to the third end of the second switching device of the bridge arm circuit.

[0016] Further, the at least one bridge arm circuit is composed of one bridge arm circuit, and the bridge circuit is configured as a half-bridge driving circuit.

[0017] Further, the at least one bridge arm circuit is composed of two bridge arm circuits, and the bridge circuit is configured as a full-bridge driving circuit.

[0018] Further, the at least one bridge arm circuit is composed of more than two of the bridge arm circuits, each of the bridge arm circuits is configured as a half-bridge drive circuit, each half-bridge drive circuit is configured with an output terminal, and the bridge circuit is configured as a half-bridge power amplifier circuit.

[0019] Further, the at least one bridge arm circuit is composed of more than two of the bridge arm circuits, wherein every two of the bridge arm circuits are configured as a full-bridge drive circuit, each full-bridge drive circuit is configured with two output terminals, and the bridge circuit is configured as a full-bridge power amplifier circuit.

[0020] Further, the at least one bridge arm circuit is composed of at least two bridge arm circuits, each of the bridge arm circuits is configured as a half-bridge drive circuit, each half-bridge drive circuit is configured with an output terminal, and the output terminals of the respective bridge arm circuits are electrically connected together to form a parallel output terminal.

[0021] Further, the first switching device and the second switching device are configured as any one or a combination of two or more of a triode, a thyristor, a MOSFET, and an IGBT.

[0022] Further, the inductance value of the at least one DC-blocking inductor is not less than the larger of U*t / i and U / (d i / dt), and the order of magnitude of the inductance value of the at least one DC-blocking inductor is less than the order of magnitude of the inductance value of the load to be driven; where U is the power supply voltage between the positive pole and the negative pole of the power supply, t is the larger of the rise time and the fall time of the first switching device and the second switching device, i is the maximum current that can be borne when the first switching device and the second switching device are conducting directly, and d i / dt is the maximum value of the current change rate of the first switching device and the second switching device.

[0023] Further, the bridge circuit further includes a filter capacitor, the filter capacitor is electrically connected between the output terminal and the ground, and the filter capacitor and the DC-blocking inductor form an LC filter circuit.

[0024] The embodiment of the present disclosure further provides a maglev system circuit, including the dead-zone-free bridge circuit described above.

[0025] The beneficial effects of the present invention are as follows: Compared with the prior art technical solution of preventing short circuits caused by arm short - circuits by setting dead - time and setting a through - protection circuit, the present invention forms a dead - time - free bridge circuit by connecting an anti - through - current inductor in series between two switching devices of the arm circuit. Among them, the anti - through - current inductor acts as a load when the switching devices of the arm circuit are short - circuited, which can prevent the PN junction of the switching device from being burned out due to excessive current, and hardly affects the output of the bridge circuit when the switching devices of the arm circuit are fully turned off or turned on. Therefore, the design of this bridge circuit is simple, and the magnetic levitation system circuit applying this bridge circuit does not need to set dead - time and other complex through - protection circuits (hardware and software), and can improve the linearity of the output of the magnetic levitation system circuit applying this bridge circuit, reduce the output waveform distortion, increase in low - order harmonics, and fundamental voltage loss caused by dead - time, etc., and improve the stability of the operation of the magnetic levitation rotor.

[0026] To make the above and other objects, features, and advantages of the present invention more obvious and understandable, the following specific preferred embodiments are given in conjunction with the accompanying drawings and are described in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0028] Figure 1 is an embodiment of a power amplification circuit of a magnetic levitation system in the prior art;

[0029] Figure 2 is the circuit diagram of Embodiment 1 of the dead - time - free bridge circuit of the present invention;

[0030] Figure 3 is the circuit diagram of Embodiment 2 of the dead - time - free bridge circuit of the present invention;

[0031] Figure 4 is the circuit diagram of Embodiment 3 of the dead - time - free bridge circuit of the present invention;

[0032] Figure 5 is the circuit diagram of Embodiment 4 of the dead - time - free bridge circuit of the present invention;

[0033] Figure 6 is the circuit diagram of Embodiment 5 of the dead - time - free bridge circuit of the present invention;

[0034] Figure 7 is the circuit diagram of Embodiment 6 of the dead - time - free bridge circuit of the present invention;

[0035] Figure 8 is the circuit diagram of the dead - zone - free bridge circuit as a full - bridge power amplifier in an embodiment of the present invention;

[0036] Figure 9 is the circuit diagram of the dead - zone - free bridge circuit as a half - bridge power amplifier (parallel) in an embodiment of the present invention;

[0037] Figure 10 is the circuit diagram of the dead - zone - free bridge circuit as a half - bridge power amplification circuit in an embodiment of the present invention;

[0038] Figure 11 is the circuit diagram of the dead - zone - free bridge circuit as a full - bridge power amplification circuit in an embodiment of the present invention. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0040] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 of the present invention. The terms "including" and "provided with" in the description and claims of the present invention and any variations thereof are intended to cover non - exclusive inclusion. For example, a system, product, or device including a series of units does not necessarily have to be limited to those units clearly listed, but may include other units not clearly listed or inherent to these products or devices.

[0041] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more, unless otherwise clearly defined.

[0042] The accompanying drawings in this disclosure are not strictly drawn to actual scale, and the specific dimensions and quantities of each structure can be determined according to actual needs. The accompanying drawings described in this disclosure are only schematic diagrams.

[0043] In the prior art, a half-bridge drive circuit or a full-bridge drive circuit composed of switching devices is indispensable in the power amplification system, sensor system, and power supply system of a magnetic levitation system. For example, the power amplification circuit for driving an electromagnetic winding in the power amplification system, the drive circuit for driving a sensor coil in the sensor system, and the inverter circuit or rectifier circuit in the power supply system, etc. Refer to Figure 1 , a power amplification circuit in a magnetic levitation system, is used to drive six electromagnetic windings (W1-W6) to generate electromagnetic torque and suspension force, so as to drive the motor to rotate and operate stably in magnetic levitation. Among them, the power amplification circuit includes six power module units (or power amplifiers) corresponding to each electromagnetic winding, and each power module unit is a full-bridge drive circuit (H-bridge circuit). The full-bridge drive circuit (two arm circuits) often sets a dead time to avoid direct conduction of the same arm. For example, the dead time should be greater than or equal to the maximum value of the turn-on and turn-off times of the arm switching devices (transistors, thyristors, MOSFETs, or IGBTs, etc.) to prevent short circuits caused by direct conduction of the upper and lower arms of the arm and avoid burning out the PN junction of the switching device due to excessive current. However, setting the dead time will, on the one hand, cause distortion of the output waveform, increase in low-order harmonics, and loss of fundamental voltage, and as the output frequency increases, the influence of the dead time on the waveform becomes more and more serious, which is a greater challenge for the magnetic levitation system for precision motion control. On the other hand, setting the dead time requires introducing a complex direct-conduction protection circuit, including hardware and software, etc. Therefore, how to solve the influence of the dead time on the power amplification system, sensor system, and power supply system of the magnetic levitation system has become an urgent technical problem to be solved.

[0044] To solve the above technical problems, refer to Figures 2 to 7, the present invention provides a dead-zone-free bridge circuit, including a power supply positive electrode, a power supply negative electrode, and at least one bridge arm circuit disposed between the power supply positive electrode and the power supply negative electrode. The bridge arm circuit includes a first switching device VT1, a second switching device VT2, and at least one anti-direct-current inductance L. The first end 11 of the first switching device VT1 is electrically connected to the power supply positive electrode. At least one anti-direct-current inductance L is connected in series between the second end 12 of the first switching device VT1 and the first end 21 of the second switching device VT2. The second end 22 of the second switching device VT2 is electrically connected to the power supply negative electrode. The third end 13 of the first switching device VT1 and the third end 23 of the second switching device VT2 are both control ends. The output end S of the bridge arm circuit is electrically connected between at least one anti-direct-current inductance L and the first end 21 of the second switching device VT2, or between at least one anti-direct-current inductance L and the second end 12 of the first switching device VT1, or between at least one anti-direct-current inductance L. In this way, by connecting the anti-direct-current inductance in series between the two switching devices of the bridge arm circuit, the anti-direct-current inductance can act as a load when the switching devices of the bridge arm circuit are short-circuited, thereby avoiding the PN junction of the switching device from being burned out due to excessive current. And when the switching devices of the bridge arm circuit are completely turned off or turned on, it hardly affects the output of the bridge circuit. The bridge circuit with the above structure has a simple design and connection. The magnetic levitation system circuit applying this bridge circuit does not need to set a dead time and other complex direct-current protection circuits (hardware and software), and can improve the linearity of the output of the magnetic levitation system circuit applying this bridge circuit, reduce the output waveform distortion, increase of low-order harmonics, and fundamental wave voltage loss caused by the dead time, and improve the stability of the operation of the magnetic levitation rotor.

[0045] According to the embodiments of the present disclosure, at least one anti-direct-current inductance can be one anti-direct-current inductance or two series-connected anti-direct-current inductances. The anti-direct-current inductance here is an inductive load inductance element, such as an inductor coil, a transformer, a magnetic bead, etc. It can be a single inductor coil or a magnetic bead, or a combination of multiple series-connected or parallel-connected inductor coils, transformers, magnetic beads, etc. The inductance value of the anti-direct-current inductance can be the inductance of a single inductive element or the total inductance of multiple inductive elements.

[0046] According to embodiments of the present disclosure, the first switching device and the second switching device are used to control the conduction and cut-off of a circuit and achieve power amplification. For example, the switching device is a power semiconductor device acting as a switch or a power amplifier, and can be, for example, any one or a combination of two or more of a triode, a thyristor, a MOSFET, and an IGBT. Similarly, the first switching device and the second switching device can be a single switching component, or a combination of multiple series-connected or parallel-connected switching components. Taking the switching device as a triode as an example, the first end of the triode is, for example, the collector, the second end of the triode is, for example, the emitter, and the third end of the triode is, for example, the base. The base of the triode plays a role in controlling the input signal, and it is the control end of the triode. The output of the triode can be controlled by changing the base voltage or current. For another example, referring to Figure 2 , the switching device can be a MOSFET, and the MOSFET is also called a MOS transistor. The first end of the MOS transistor is, for example, the drain, the second end of the MOS transistor is, for example, the source, and the third end of the MOS transistor is, for example, the gate. The gate of the MOS transistor plays a role in controlling the conduction and cut-off of the MOS transistor. When a certain voltage is applied to the gate, the MOS transistor can be turned on, and vice versa, it is turned off. Other switching devices such as thyristors and IGBTs have similar principles of controlling conduction and cut-off to triodes and MOS transistors, which will not be elaborated here.

[0047] According to embodiments of the present disclosure, the positive power supply terminal and the negative power supply terminal are used to supply a power supply voltage to the bridge arm circuit. For example, referring to Figure 2 , the power supply voltage can be the voltage between the positive and negative poles of a DC power supply DC, or the voltage of a DC bus.

[0048] According to an embodiment of the present disclosure, connecting an anti-shoot-through inductor in series between the second end 12 of the first switching device VT1 and the first end 21 of the second switching device VT2 in the leg circuit can prevent shoot-through in the leg circuit. For example, during the switching process of two switching devices (the first switching device and the second switching device), due to the inconsistency between the rising edge time (turn-on delay time) and the falling edge time (turn-off delay time) of the switching devices, there is a possibility of shoot-through in the leg. Connecting an anti-shoot-through inductor between the two switching devices, by utilizing the inductive load effect of the anti-shoot-through inductor, short circuit in the leg can be avoided when shoot-through occurs, thereby preventing the PN junction of the switching device from being burned out due to excessive current. After connecting an anti-shoot-through inductor in the leg circuit, it may have a certain impact on the output of the leg circuit. This is because when one switching device is completely turned off and the other switching device is completely turned on, the anti-shoot-through inductor and the load to be driven are in series for voltage division, which may have a slight impact on the output. Therefore, by optimizing the inductance value of the anti-shoot-through inductor, the purpose of balancing anti-shoot-through protection and reducing the impact on the output can be achieved. The value of the anti-shoot-through inductor is affected by the current in the leg circuit during shoot-through and the current change rate of the switching device on the one hand, and by the inductance of the load to be driven on the other hand. Preferably, the inductance value of at least one anti-shoot-through inductor is not less than the larger of U*t / i and U / (d i / dt), and the order of magnitude of the inductance value of at least one anti-shoot-through inductor is less than the order of magnitude of the inductance value of the load to be driven; where U is the power supply voltage or bus voltage between the positive power supply terminal and the negative power supply terminal, t is the larger of the rising edge time and the falling edge time of the first switching device or the second switching device, i is the maximum current that the first switching device or the second switching device can withstand during shoot-through, and d i / dt is the maximum value of the current change rate of the first switching device or the second switching device. Wherein, t is the larger of the rising edge time and the falling edge time of the switching device, and more preferably, t can be the sum of the rising edge time and the falling edge time of the switching device. The meaning that the value of the anti-shoot-through inductor is not less than U*t / i can be understood as that the anti-shoot-through inductor prevents the current in the leg circuit from rising to the maximum current that the first switching device and the second switching device can withstand within the shoot-through time (the larger of the rising edge time and the falling edge time), thereby achieving the effect of protecting the switching device. The maximum current that the switching device can withstand is affected by factors such as circuit design, environment, and derating. Therefore, preferably, the value of i can be selected to be smaller than the actual maximum current that the switching device can withstand. In this way, the value of the anti-shoot-through inductor can be selected to be slightly larger. And when the first switching device and the second switching device are completely turned on or completely turned off, since the anti-shoot-through inductor is in series with the load to be driven, in order to reduce the voltage division effect of the series-connected anti-shoot-through inductor on the load to be driven, the inductance of the anti-shoot-through inductor should not be too large, that is, the anti-shoot-through inductor is usually selected as a small inductor. For example, the order of magnitude of the inductance value of at least one anti-shoot-through inductor is less than the order of magnitude of the inductance value of the load to be driven.Here, the order of magnitude refers to a series of powers of 10, that is, the ratio between two adjacent orders of magnitude is 10. For example, the inductance value of the DC-blocking inductor is 1 μH while the inductance of the load to be driven is 1 mH, and the two differ by three orders of magnitude. Preferably, on the basis of ensuring that the DC-blocking inductor can protect the switching device, the value of the DC-blocking inductor can be selected to be relatively small. For example, the value of the DC-blocking inductor can be less than the parasitic inductance on the cable of the output loop, so as to achieve the purpose of having almost no impact on the inductance of the output loop. In addition, the meaning that the value of the DC-blocking inductor is not less than U / (d i / dt) can be understood as that the current change rate d ix / dt in the leg circuit during direct conduction should not exceed d i / dt, where d i / dt is the maximum value of the current change rate of the first switching device or the second switching device. Assuming that the bus voltage is fully applied to the DC-blocking inductor during direct conduction, that is, (d ix / dt) = U / L, because it is necessary to ensure that U / L is less than or equal to di / dt, the inductance value of the DC-blocking inductor should not be less than U / (d i / dt). In order to simultaneously meet the requirements of the current and current change rate in the leg circuit during direct conduction, the inductance value of at least one DC-blocking inductor should be selected to be not less than the larger of U*t / i and U / (d i / dt). The maximum value of the current change rate of the switching device can be obtained according to the maximum value of d i / dt specified in the device manual or calculated from the maximum value of dv / dt. In order to make the switching device in the bridge circuit meet the design requirements, d i / dt can also be adjusted by adjusting the resistance of the control terminal of the switching device.

[0049] Embodiment 1

[0050] In one embodiment, referring to Figure 2 , at least one DC-blocking inductor of the dead-time-free bridge circuit is configured as a DC-blocking inductor L, and the output terminal S of the leg circuit is electrically connected between the DC-blocking inductor L and the first terminal 21 of the second switching device VT2. That is, the second terminal 12 of the first switching device VT1 is electrically connected to one end of the DC-blocking inductor L, and the other end of the DC-blocking inductor L is electrically connected to the first terminal 21 of the second switching device VT2. The connection line between the DC-blocking inductor L and the second switching device VT2 leads out the output terminal S of the leg circuit. The output terminal of the leg circuit can be connected to the load to be driven, such as the sensor coil of the displacement detection circuit in the sensor system, or the coil of the electromagnetic winding of the magnetic levitation stator, or the load of the power system, etc. In this way, during the switching process of the first switching device and the second switching device, the DC-blocking inductor L can act as a load to avoid short circuit of the leg and thus avoid burning out of the PN junction of the switching device due to excessive current. After the first switching device and the second switching device are completely turned off or completely turned on, the DC-blocking inductor L has almost no impact on the output of the bridge circuit.

[0051] Embodiment 2

[0052] In one embodiment, referring toFigure 3 In this case, at least one DC-blocking inductor of the dead-time-free bridge circuit is also configured as a DC-blocking inductor L. Different from the above Embodiment 1, the output terminal S of the bridge arm circuit is electrically connected between the DC-blocking inductor L and the second terminal 12 of the first switching device VT1. That is, the second terminal 12 of the first switching device VT1 is electrically connected to one end of the DC-blocking inductor L, and the other end of the DC-blocking inductor L is electrically connected to the first terminal 21 of the second switching device VT2. The connection line between the DC-blocking inductor L and the first switching device VT1 leads out the output terminal of the bridge arm circuit. Similarly, during the switching process of the first switching device and the second switching device, the DC-blocking inductor L can act as a load to avoid short-circuiting of the bridge arm, thereby preventing the PN junction of the switching device from being burned out due to excessive current. After the first switching device and the second switching device are completely turned off or completely turned on, the DC-blocking inductor L has almost no influence on the output of the bridge circuit.

[0053] Embodiment 3

[0054] In one embodiment, referring to Figure 4 In this case, the number of at least one DC-blocking inductor of the dead-time-free bridge circuit is configured as two, which are respectively denoted as the first DC-blocking inductor L1 and the second DC-blocking inductor L2. The output terminal S of the bridge arm circuit is electrically connected to the connection line between the first DC-blocking inductor L1 and the second DC-blocking inductor L1. For example, the second terminal 12 of the first switching device VT1 is electrically connected to one end of the first DC-blocking inductor L1, the other end of the first DC-blocking inductor L1 is electrically connected to one end of the second DC-blocking inductor L2, the other end of the second DC-blocking inductor L2 is electrically connected to the first terminal 21 of the second switching device VT2, and the connection line between the first DC-blocking inductor L1 and the second DC-blocking inductor L2 leads out the output terminal S of the bridge arm circuit. Different from the above Embodiment 1 and Embodiment 2, two DC-blocking inductors are provided in this embodiment, for example, the same or nearly the same DC-blocking inductors. In this way, by connecting two DC-blocking inductors in series between the two switching devices of the bridge arm circuit and configuring the output terminal of the bridge arm circuit on the connection line between the two DC-blocking inductors, it is possible to ensure the consistency of the influence of the series-connected DC-blocking inductors on the output of the bridge circuit when the bridge arm circuit is not in direct connection (one switching device is completely turned on and the other switching device is completely turned off), thereby ensuring the consistent stability of the output characteristics of the bridge circuit.

[0055] Embodiment 4

[0056] In one embodiment, referring to Figure 5, the number of at least one DC-blocking inductor of the dead-zone-free bridge circuit is configured to be two, which are respectively denoted as the first DC-blocking inductor L1 and the second DC-blocking inductor L2, and the output terminal S of the bridge arm circuit is electrically connected to the connection line between the first DC-blocking inductor L1 and the second DC-blocking inductor L2. Different from the above Embodiment 3, the bridge arm circuit of this embodiment further includes a first freewheeling diode D1, a second freewheeling diode D2, a third freewheeling diode D3, and a fourth freewheeling diode D4. The first freewheeling diode D1 is connected in parallel between the first terminal 11 of the first switching device VT1 and the connection line, and the third freewheeling diode D3 is connected in parallel between the second terminal 12 of the first switching device VT1 and the connection line; the second freewheeling diode D2 is connected in parallel between the second terminal 22 of the second switching device VT2 and the connection line, and the fourth freewheeling diode D4 is connected in parallel between the first terminal 21 of the second switching device VT2 and the connection line; that is, the negative terminal of the first freewheeling diode D1 is electrically connected to the first terminal 11 of the first switching device VT1, and the positive terminal of the first freewheeling diode D1 is electrically connected to the connection line between the first DC-blocking inductor L1 and the second DC-blocking inductor L2. That is, the negative terminal of the third freewheeling diode D3 is electrically connected to the second terminal 12 of the first switching device VT1, and the positive terminal of the third freewheeling diode D3 is electrically connected to the connection line between the first DC-blocking inductor L1 and the second DC-blocking inductor L2. The positive terminal of the second freewheeling diode D2 is electrically connected to the second terminal 22 of the second switching device VT2, and the negative terminal of the second freewheeling diode D2 is electrically connected to the connection line between the first DC-blocking inductor L1 and the second DC-blocking inductor L2. The positive terminal of the fourth freewheeling diode D4 is electrically connected to the first terminal 21 of the second switching device VT2, and the negative terminal of the fourth freewheeling diode D4 is electrically connected to the connection line between the first DC-blocking inductor L1 and the second DC-blocking inductor L2. In this way, by connecting freewheeling diodes in parallel at both ends of the whole of a switching device and a series-connected DC-blocking inductor, and directly connecting another freewheeling diode in parallel at both ends of the DC-blocking inductor, during the switching process of the switching device of the bridge arm circuit, the freewheeling of the DC-blocking inductor and the freewheeling of the switching device can be realized, and the freewheeling time can be made faster on the basis of the same influence on the two switching devices. For example, when the first switching device is turned off and the second freewheeling diode is freewheeling, the second freewheeling diode D2 can bypass the second DC-blocking inductor L2, thereby accelerating the freewheeling time, and the third freewheeling diode D3 can release the current of the first DC-blocking inductor. Similarly, when the second switching device is turned off and the first freewheeling diode is freewheeling, the first freewheeling diode D1 can bypass the first DC-blocking inductor L1, thereby accelerating the freewheeling time, and the fourth freewheeling diode D4 can release the current of the second DC-blocking inductor L2. In this way, through the setting of the first freewheeling diode to the fourth freewheeling diode, the influence of the series-connected DC-blocking inductor on the output of the bridge circuit can be further reduced.

[0057] Embodiment 5

[0058] In one embodiment, refer toFigure 6, the number of at least one DC-blocking inductor of the dead-zone-free bridge circuit is configured to be two, which are respectively denoted as the first DC-blocking inductor L1 and the second DC-blocking inductor L2, and the output terminal S of the bridge arm circuit is electrically connected to the wire between the first DC-blocking inductor L1 and the second DC-blocking inductor L2. Different from the above-mentioned Embodiment 3, the bridge arm circuit of this embodiment further includes a first freewheeling diode D1, a second freewheeling diode D2, a third freewheeling diode D3 and a fourth freewheeling diode D4. The first freewheeling diode D1 is connected in parallel between the first terminal 11 and the second terminal 12 of the first switching device VT1. The third freewheeling diode D3 is connected in parallel between the second terminal 12 of the first switching device VT1 and the wire, and the positive terminal of the first freewheeling diode D1 is connected in series with the negative terminal of the third freewheeling diode D3. The second freewheeling diode D2 is connected in parallel between the second terminal 22 and the first terminal 21 of the second switching device VT2. The fourth freewheeling diode D4 is connected in parallel between the first terminal 21 of the second switching device VT2 and the wire, and the positive terminal of the fourth freewheeling diode D4 is connected in series with the negative terminal of the second freewheeling diode D2. That is, the negative terminal of the first freewheeling diode D1 is electrically connected to the first terminal 11 of the first switching device VT1, and the positive terminal of the first freewheeling diode D1 is electrically connected to the second terminal 12 of the first switching device VT1. The negative terminal of the third freewheeling diode D3 is electrically connected to the second terminal 12 of the first switching device VT1, and the negative terminal of the third freewheeling diode D3 is electrically connected to the positive terminal of the first freewheeling diode D1. The positive terminal of the third freewheeling diode D3 is electrically connected to the wire between the first DC-blocking inductor L1 and the second DC-blocking inductor L2. The positive terminal of the second freewheeling diode D2 is electrically connected to the second terminal 22 of the second switching device VT2, the negative terminal of the second freewheeling diode D2 is electrically connected to the first terminal 21 of the second switching device VT2, and is electrically connected to the positive terminal of the fourth freewheeling diode D4. The positive terminal of the fourth freewheeling diode D4 is electrically connected to the first terminal 21 of the second switching device VT2, and the negative terminal of the fourth freewheeling diode D4 is electrically connected to the wire between the first DC-blocking inductor L1 and the second DC-blocking inductor L2. In this way, by connecting a freewheeling diode in parallel at both ends of a switching device, directly connecting another freewheeling diode in parallel at both ends of the DC-blocking inductor, and making the two freewheeling diodes in series, the freewheeling of the DC-blocking inductor and the freewheeling of the switching device can be realized during the switching process of the switching device of the bridge arm circuit, and the freewheeling time can be made faster on the basis of the same influence on the two switching devices. For example, when the first switching device is turned off and the second freewheeling diode is freewheeling, the series-connected second freewheeling diode D2 and fourth freewheeling diode D4 can bypass the second DC-blocking inductor L2, thereby accelerating the freewheeling time, and the third freewheeling diode D3 can release the current of the first DC-blocking inductor.Similarly, during the turn-off of the second switching device VT2 and the freewheeling of the first freewheeling diode D1, the series-connected first freewheeling diode D1 and third freewheeling diode D3 can bypass the first DC-blocking inductor L1, thereby accelerating the freewheeling time, and the fourth freewheeling diode D4 can discharge the current of the second DC-blocking inductor L2. In this way, by arranging the first to fourth freewheeling diodes, the influence of the series DC-blocking inductors on the output of the bridge circuit can be further reduced.

[0059] Embodiment 6

[0060] In one embodiment, referring to Figure 7 , the number of at least one DC-blocking inductor of the dead-time-free bridge circuit is configured to be two, denoted as the first DC-blocking inductor L1 and the second DC-blocking inductor L2 respectively. The output terminal S of the bridge arm circuit is electrically connected to the connection line between the first DC-blocking inductor L1 and the second DC-blocking inductor L2. The bridge arm circuit further includes a first freewheeling diode D1, a second freewheeling diode D2, a third freewheeling diode D3, and a fourth freewheeling diode D4. Different from the above Embodiments 4 and 5, the bridge circuit further includes a bootstrap circuit. The bootstrap circuit includes a bootstrap diode D5, a bootstrap capacitor C2, and a driving chip. The anode of the bootstrap diode D5 is electrically connected to the power supply VCC, the cathode of the bootstrap diode D5 is electrically connected to the first end of the bootstrap capacitor C2, the second end of the bootstrap capacitor C2 is electrically connected to the connection line between the second end 12 of the first switching device VT1 and the first DC-blocking inductor L1, and the second end of the bootstrap capacitor C2 is electrically connected to the VS pin of the driving chip. The H0 pin of the driving chip is electrically connected to the third end 13 of the first switching device VT1 of the bridge arm circuit, and the L0 pin of the driving chip is electrically connected to the third end 23 of the second switching device VT2 of the bridge arm circuit. Among them, the bootstrap circuit is also called a boost circuit, which uses a bootstrap diode, a bootstrap capacitor, and a driving chip to superimpose the discharge voltage of the bootstrap capacitor and the power supply voltage (such as a DC power supply DC), thereby increasing the voltage. In other embodiments, a first resistor R1, a second resistor R2, and a third resistor R3 are further included. The first resistor R1 is connected in series between the HO pin of the driving chip and the third end 13 of the first switching device VT1, for example, the base resistor of a MOSFET. Similarly, the second resistor R2 is connected in series between the LO pin of the driving chip and the third end 23 of the second switching device VT2. For example, it is the base resistor of a MOSFET. By adjusting the first resistor and the second resistor (base resistor), the purpose of adjusting the current change rate (di / dt) of the first switching device and the second switching device can be achieved to meet the design requirements. The third resistor R3 is connected in series between the bootstrap diode D5 and the power supply VCC and serves as a bootstrap resistor to limit the current flowing through the bootstrap diode during startup.

[0061] Among them, the bootstrap diode D5 is used to prevent current backflow. When the frequency is relatively high, the voltage of the bootstrap circuit is the sum of the input voltage of the circuit and the voltage on the bootstrap capacitor, which plays a role in boosting the voltage. Refer to Figure 7 , when there is no series DC-blocking inductor, the bootstrap process is as follows: when the second switching device VT2 conducts and makes the VS of the driving chip drop below the power supply voltage VCC, VCC charges the bootstrap capacitor C2 through the bootstrap diode D5 and the bootstrap resistor R3, generating a floating voltage Vbs across the bootstrap capacitor C2 to support the switching of HO relative to VS. As the first switching device VT1 switches, the bootstrap diode D5 is reverse-biased when VS is at a high voltage, isolating Vbs from the power supply VCC. The technical principle of the bootstrap circuit is prior art and will not be elaborated here. It should be noted that in this embodiment, due to the series-connected first DC-blocking inductor L1 and second DC-blocking inductor L2 between the first switching device VT1 and the second switching device VT2, in this embodiment, connecting the second end of the bootstrap capacitor C2 and the VS pin of the driving chip to the connection line between the second end 12 of the first switching device VT1 and the first DC-blocking inductor L1 can eliminate the influence of the series DC-blocking inductor on the bootstrap circuit. For example, when the first switching device VT1 is fully turned off and the second switching device VT2 is fully turned on, the current change rate on the two DC-blocking inductors is almost zero, so the voltage drop across the two DC-blocking inductors is very small. At this time, the bootstrap capacitor C2 is charged, and the first DC-blocking inductor L1 and the second DC-blocking inductor L2 have basically no influence on the operating voltage of the bootstrap circuit. When the first switching device VT1 is fully turned on and the second switching device VT2 is fully turned off, since the VS pin and the bootstrap capacitor C2 are directly electrically connected to the second end (emitter) of the first switching device, the first DC-blocking inductor L1 and the second DC-blocking inductor L2 will not affect the discharge and boost process of the bootstrap capacitor.

[0062] Refer to Figures 2 to 7 , based on the technical solutions of the above embodiments, in this embodiment, the bridge circuit further includes a filter capacitor C1, and the filter capacitor C1 is electrically connected between the output terminal S and the ground. The filter capacitor C1 and the DC-blocking inductor L form an LC filter circuit. In this way, by using the DC-blocking inductor L introduced into the bridge circuit and the filter capacitor to form an LC filter circuit, and using the impedance effect of the inductor element on high-frequency signals, high-frequency signals in the system can be filtered out, improving the frequency characteristics of the system. For example, refer to Figure 2 and Figure 3 , when the number of at least one DC-blocking inductor is configured as one DC-blocking inductor L, the DC-blocking inductor L and the filter capacitor C1 can form an LC filter circuit, thereby achieving the purpose of improving the frequency characteristics of the output signal of the bridge circuit. Refer to Figures 4 to 7 , when the number of at least one DC-blocking inductor is configured as two DC-blocking inductors, the first DC-blocking inductor L1 and the second DC-blocking inductor L2 together with the filter capacitor C1 form an LC filter circuit.

[0063] In each of the above embodiments, the first freewheeling diode, the second freewheeling diode, the third freewheeling diode, and the fourth freewheeling diode function to freewheel or release current. Usually, a freewheeling diode is built into some switching devices. At this time, compared with the preferred embodiment 5, only another freewheeling diode needs to be connected in parallel across the anti-direct-current inductor, and the built-in freewheeling diode is connected in series with the other freewheeling diode to achieve the purpose of accelerating the freewheeling time and releasing current.

[0064] In each of the above embodiments, the dead-time-free bridge circuit can be used to drive different loads according to different application scenarios. See Figure 6 , at least one bridge arm circuit consists of one bridge arm circuit, and the bridge circuit is configured as a half-bridge drive circuit. The half-bridge drive circuit can be used as the drive for, for example, a sensor coil. Similarly, see Figure 8 , at least one bridge arm circuit consists of two bridge arm circuits, that is, one bridge arm circuit consists of a first switching device VT1, a second switching device VT2, a first anti-direct-current inductor L1, a second anti-direct-current inductor L2, a first freewheeling diode D1, a second freewheeling diode D2, a third freewheeling diode D3, and a fourth freewheeling diode D4; the other bridge arm circuit consists of a first switching device VT1', a second switching device VT2', a first anti-direct-current inductor L1', a second anti-direct-current inductor L2', a first freewheeling diode D1', a second freewheeling diode D2', a third freewheeling diode D3', and a fourth freewheeling diode D4'. The bridge circuit is configured as a full-bridge drive circuit, that is, an H-bridge circuit. Each of the two bridge arm circuits of the full-bridge drive circuit leads out an output terminal, and a sensor coil is connected between the two output terminals, which can also be used as the drive circuit for the sensor coil.

[0065] In one embodiment, see Figure 9 , at least one bridge arm circuit consists of at least two bridge arm circuits, each bridge arm circuit is configured as a half-bridge drive circuit, each half-bridge drive circuit is configured with an output terminal S, and the output terminals of each bridge arm circuit are electrically connected together to form a parallel output terminal S'. For example, see Figure 9, at least one bridge arm circuit is composed of two bridge arm circuits. That is, one bridge arm circuit is composed of a first switching device VT1, a second switching device VT2, a first DC-blocking inductor L1, a second DC-blocking inductor L2, a first freewheeling diode D1, a second freewheeling diode D2, a third freewheeling diode D3, and a fourth freewheeling diode D4; the other bridge arm circuit is composed of a first switching device VT1', a second switching device VT2', a first DC-blocking inductor L1', a second DC-blocking inductor L2', a first freewheeling diode D1', a second freewheeling diode D2', a third freewheeling diode D3', and a fourth freewheeling diode D4'. The output terminals S of each bridge arm circuit are electrically connected together to form a parallel output terminal S'. The bridge circuit is configured as a parallel half-bridge drive circuit. By electrically connecting the output terminals of the two bridge arm circuits together to form a parallel half-bridge drive circuit, the driving ability of the bridge circuit can be improved. For example, if the current output by each of the two bridge arm circuits is A, then the output of the parallel half-bridge drive circuit is 2A. Since two bridge arm circuits without series-connected DC-blocking inductors in the prior art cannot be connected in parallel for output, while in the present invention, the parallel output of the two bridge arm circuits can be achieved after series-connected DC-blocking inductors, so as to achieve the purpose of improving the driving ability of the bridge circuit.

[0066] In one embodiment, refer to Figure 10 , at least one bridge arm circuit is composed of more than two bridge arm circuits. Each bridge arm circuit is configured as a half-bridge drive circuit, and each half-bridge drive circuit is configured with an output terminal. The bridge circuit is configured as a half-bridge power amplifier circuit. For example, the half-bridge power amplifier circuit can be used to drive multiple electromagnetic windings of a magnetic levitation stator. Refer to Figure 10 , in an application of a magnetic levitation motor with 6 electromagnetic windings, the half-bridge power amplifier circuit can be used to control the current or voltage input to the 6 electromagnetic windings of the magnetic levitation stator, so as to achieve the purpose of driving the magnetic levitation rotor to rotate and levitate by the magnetic levitation stator. Similarly, in another embodiment, at least one bridge arm circuit is composed of more than two bridge arm circuits, wherein every two bridge arm circuits are configured as a full-bridge drive circuit, and each full-bridge drive circuit is configured with two output terminals. The bridge circuit is configured as a full-bridge power amplifier circuit.

[0067] Refer to Figure 11 , in an application of a magnetic levitation motor with 3-phase electromagnetic windings, the full-bridge power amplifier circuit can be used to control the current or voltage input to the 3-phase electromagnetic windings of the magnetic levitation stator, so as to achieve the purpose of driving the magnetic levitation rotor to rotate or levitate by the magnetic levitation stator.

[0068] In other embodiments, a power amplification circuit or a power amplifier is used to amplify the power of a signal to an appropriate level for effectively driving a load. For example, in a power system, a power amplifier is used to amplify the power of a signal to a level sufficient to control and drive various power equipment and devices. For example, a power amplifier is used to control power equipment such as electric motors, electric valves, and electromagnetic relays. In industrial automation and control systems, power amplifiers are used to amplify and control various sensor signals to achieve precise control of the control system.

[0069] Specific embodiments are applied in the present invention to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the technical solution and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A dead-zone-free bridge circuit, characterized in that, it includes a power supply positive electrode, a power supply negative electrode, and at least one bridge arm circuit disposed between the power supply positive electrode and the power supply negative electrode. The bridge arm circuit includes a first switching device (VT1), a second switching device (VT2), and at least one DC-blocking inductor (L). The first end (11) of the first switching device is electrically connected to the power supply positive electrode. The at least one DC-blocking inductor is connected in series between the second end (12) of the first switching device and the first end (21) of the second switching device. The second end (22) of the second switching device is electrically connected to the power supply negative electrode. The third end (13) of the first switching device and the third end (23) of the second switching device are both control ends. The output end (S) of the bridge arm circuit is electrically connected between the at least one DC-blocking inductor and the first end of the second switching device, or between the at least one DC-blocking inductor and the second end of the first switching device, or between the at least one DC-blocking inductors.

2. The dead-zone-free bridge circuit according to claim 1, characterized in that, the number of the at least one DC-blocking inductor is configured as one, denoted as the DC-blocking inductor (L). The output end of the bridge arm circuit is electrically connected between the DC-blocking inductor and the first end of the second switching device, or between the DC-blocking inductor and the second end of the first switching device.

3. The dead-zone-free bridge circuit according to claim 1, characterized in that, the number of the at least one DC-blocking inductor is configured as two, denoted as a first DC-blocking inductor (L1) and a second DC-blocking inductor (L2). The output end of the bridge arm circuit is electrically connected to the connection line between the first DC-blocking inductor and the second DC-blocking inductor.

4. The dead-zone-free bridge circuit according to claim 3, characterized in that, the bridge arm circuit further includes a first freewheeling diode (D1), a second freewheeling diode (D2), a third freewheeling diode (D3), and a fourth freewheeling diode (D4). The first freewheeling diode is connected in parallel between the first end of the first switching device and the connection line. The third freewheeling diode is connected in parallel between the second end of the first switching device and the connection line. The second freewheeling diode is connected in parallel between the second end of the second switching device and the connection line. The fourth freewheeling diode is connected in parallel between the first end of the second switching device and the connection line. Or, the first freewheeling diode is connected in parallel between the first end and the second end of the first switching device. The third freewheeling diode is connected in parallel between the second end of the first switching device and the connection line, and the positive terminal of the first freewheeling diode is connected in series with the negative terminal of the third freewheeling diode. The second freewheeling diode is connected in parallel between the first end and the second end of the second switching device. The fourth freewheeling diode is connected in parallel between the first end of the second switching device and the connection line, and the positive terminal of the fourth freewheeling diode is connected in series with the negative terminal of the second freewheeling diode.

5. The dead-zone-free bridge circuit according to any one of claims 1-4, characterized in that, The bridge circuit further includes a bootstrap circuit, and the bootstrap circuit includes a bootstrap diode (D5), a bootstrap capacitor (C2), and a driving chip. The anode of the bootstrap diode is electrically connected to a power supply (VCC), the cathode of the bootstrap diode is electrically connected to the first end of the bootstrap capacitor, the second end of the bootstrap capacitor is electrically connected to the connection line between the second end of the first switching device and the first DC-blocking inductor, and the second end of the bootstrap capacitor is electrically connected to the VS pin of the driving chip. The H0 pin of the driving chip is electrically connected to the third end of the first switching device of the leg circuit, and the L0 pin of the driving chip is electrically connected to the third end of the second switching device of the leg circuit.

6. The dead-time-free bridge circuit according to any one of claims 1-4, wherein, the at least one leg circuit is composed of one such leg circuit, and the bridge circuit is configured as a half-bridge driving circuit.

7. The dead-time-free bridge circuit according to any one of claims 1-4, wherein, the at least one leg circuit is composed of two such leg circuits, and the bridge circuit is configured as a full-bridge driving circuit.

8. The dead-time-free bridge circuit according to any one of claims 1-4, wherein, the at least one leg circuit is composed of more than two such leg circuits. Each such leg circuit is configured as a half-bridge driving circuit, and each half-bridge driving circuit is configured with an output terminal. The bridge circuit is configured as a half-bridge power amplification circuit.

9. The dead-time-free bridge circuit according to any one of claims 1-4, wherein, the at least one leg circuit is composed of more than two such leg circuits. Among them, every two such leg circuits are configured as a full-bridge driving circuit, and each full-bridge driving circuit is configured with two output terminals. The bridge circuit is configured as a full-bridge power amplification circuit.

10. The dead-time-free bridge circuit according to any one of claims 1-4, wherein, the at least one leg circuit is composed of at least two leg circuits. Each leg circuit is configured as a half-bridge driving circuit, and each half-bridge driving circuit is configured with an output terminal. The output terminals of each leg circuit are electrically connected together to form a parallel output terminal.

11. The dead-time-free bridge circuit according to any one of claims 1-4, wherein, the first switching device and the second switching device are configured as any one or a combination of two or more of a triode, a thyristor, a MOSFET, and an IGBT.

12. The dead-time-free bridge circuit according to any one of claims 1-4, wherein, the inductance value of the at least one DC-blocking inductor is not less than the larger of U*t / i and U / (di / dt), and the order of magnitude of the inductance value of the at least one DC-blocking inductor is less than the order of magnitude of the inductance value of the load to be driven; where U is the power supply voltage between the positive pole and the negative pole of the power supply, t is the larger of the rising edge time and the falling edge time of the first switching device and the second switching device, i is the maximum current that can be tolerated when the first switching device and the second switching device are conducting directly, and di / dt is the maximum value of the current change rate of the first switching device and the second switching device.

13. The dead-zone-free bridge circuit according to any one of claims 1-4, characterized in that, the bridge circuit further includes a filter capacitor (C1), the filter capacitor is electrically connected between the output terminal and the ground, and the filter capacitor and the DC-blocking inductor form an LC filter circuit.

14. A magnetic levitation system circuit, characterized in that, it includes the dead-zone-free bridge circuit according to any one of claims 1-13.

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