An anti-interference half-bridge drive circuit for controlling LLC resonance

Abstract

The present invention relates to an anti-interference half-bridge driving circuit for controlling LLC resonance, comprising a pulse generator, first and second high-voltage MOS tubes, first to third MOS tubes, first and second resistors, an RS trigger, first and second voltage regulator diodes, the source of the third MOS tube is led out as the HS terminal of the circuit, and the common connection terminal of the gates of the second and third MOS tubes is led out as the HO terminal of the circuit. The first MOS tube adopts a PMOS tube, and when the signal level of the HS terminal suddenly changes from a low level to a high level, the R terminal undershoot signal of the RS trigger will turn on the first MOS tube, and the S terminal level of the RS trigger will be clamped at a high level, so that the R terminal undershoot signal will not cause the HO terminal to malfunction. At the same time, the introduction of the first and second voltage regulator tubes can well protect the circuits of the R and S terminals of the RS trigger to work in a safe voltage range. Therefore, after the first MOS tube and the first and second voltage regulator tubes are introduced into the present circuit, the interference caused by the sudden change of the level of the HS terminal of the circuit can be well resisted, and the stable and safe operation of the half-bridge driving circuit is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-interference of LLC resonance control, and in particular to an anti-interference half-bridge driving circuit for controlling LLC resonance. Background Art

[0002] In such Figure 1 In the half-bridge driving circuit for controlling LLC resonance shown in the figure, the circuit 002 with half-bridge driving drives and controls the LLC resonance primary power tubes 004 and 005, wherein the drain of the NMOS tube 004 is connected to the high voltage power supply VH. The NMOS tubes 004 and 005, the inductor 006, the transformer 010, and the capacitor 009 constitute an LLC resonant loop, the transformer 010, the diodes 011 and 012, and the capacitor 013 constitute a full-wave rectifier circuit, and the load is externally connected to the two ends VOUT of the capacitor 013. The transformer 007 and the resistor 008 constitute a current sampling circuit, which converts the current signal of the LLC resonant loop into a voltage signal and feeds it back to the circuit 002 with half-bridge driving. The diode 001 and the capacitor 003 constitute a bootstrap circuit to provide power for the high-side driving channel in the circuit with half-bridge driving.

[0003] In the circuit with half-bridge drive, PGND is the power ground, LO is the low-side gate output of the half-bridge drive, PVCC is the power supply, NC is an empty pin, HS is the high-side ground of the half-bridge drive, HO is the high-side gate output of the half-bridge drive, and HB is the high-side power supply of the half-bridge drive.

[0004] When the half-bridge drive circuit that controls LLC resonance is working, the output signal waveform of the half-bridge drive circuit is as follows: Figure 2 As shown in the figure, at time t1, when the LO terminal turns off the NMOS tube 005, since the current on the inductor 006 cannot change suddenly, the current flowing through the inductor 006 and the NMOS tube 005 to the ground is converted into the current flowing through the inductor 006 and the NMOS tube 004 to the high-voltage power supply VH, and the signal level of the HS terminal changes from a low level to a high level in a very short time (100nS-1uS). Similarly, at time t3, when the HO terminal turns off the NMOS tube 004, the signal level of the HS terminal changes from a high level to a low level in a very short time (100nS-1uS). As the high-side ground of the half-bridge drive, the sudden change of the HS terminal level will cause great interference to the half-bridge drive circuit, which is easy to cause errors in the output logic of the half-bridge drive circuit, and then cause interference to the LLC resonant loop. Summary of the invention

[0005] The object of the present invention is to provide an anti-interference half-bridge driving circuit for controlling LLC resonance which has a simple structure, is easy to implement and has a low cost.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is an anti-interference half-bridge driving circuit for controlling LLC resonance, comprising a pulse generator, first and second high-voltage MOS tubes, first to third MOS tubes, first and second resistors, RS trigger, first and second voltage regulator diodes, the input end of the pulse generator inputs a square wave signal, the output end of the pulse generator is respectively connected to the gates of the first and second high-voltage MOS tubes, the sources of the first and second high-voltage MOS tubes are grounded, the drains of the first and second high-voltage MOS tubes are respectively connected to one end of the first and second resistors, the other ends of the first and second resistors are led out as a power supply for the half-bridge high-side circuit, and are led out as an HB end, the drain of the first MOS tube is connected between the drain of the first high-voltage MOS tube and the first resistor, and the gate of the first MOS tube is connected to the drain of the second high-voltage MOS tube and the second resistor The source of the first MOS tube is connected between the first and second resistors, the anode of the first voltage regulator diode is connected between the drain of the first high-voltage MOS tube and the first resistor, the anode of the second voltage regulator diode is connected between the drain of the second high-voltage MOS tube and the second resistor, the cathodes of the first and second voltage regulator diodes are both connected to the HB terminal, the S terminal of the RS trigger is connected to the anode of the first voltage regulator diode, the R terminal of the RS trigger is connected to the anode of the second voltage regulator diode, the output terminal of the RS trigger is connected to the input terminal of the output pre-driving circuit, the output terminal of the output pre-driving circuit is connected to the gates of the second and third MOS tubes, the drain of the second MOS tube is connected to the drain of the third MOS tube, the source of the second MOS tube is connected to the HB terminal, the source of the third MOS tube is led out as the HS terminal of the circuit, and the common terminal of the gates of the second and third MOS tubes is led out as the HO terminal of the circuit.

[0007] As an improvement of the present invention, the first and second high-voltage MOS tubes are high-voltage NMOS tubes.

[0008] As an improvement of the present invention, the first MOS tube is a PMOS tube.

[0009] As an improvement of the present invention, the second MOS tube is a PMOS tube, and the third MOS tube is an NMOS tube.

[0010] As an improvement of the present invention, the first and second resistors are implemented by resistors.

[0011] Compared with the prior art, the overall structure design of the half-bridge driving circuit of the present invention is ingenious, the structure is simple and reliable, and only two voltage regulators, namely, the first MOS tube (PMOS tube) and the first and second voltage regulator diodes, are introduced into the circuit. After the first MOS tube is introduced into the present circuit, when the signal level at the HS end of the circuit suddenly changes from a low level to a high level signal, the undershoot signal at the R end of the RS trigger will turn on the first MOS tube to clamp the level at the S end at a high level, and the undershoot signal at the R end will not cause the signal output at the HO end to malfunction, so that the first MOS tube clamps the level at the S end of the RS trigger, greatly improving the anti-interference ability of the half-bridge driving circuit. In the present circuit, the first voltage regulator diode and the second voltage regulator diode are introduced, and when the signal level at the HS end of the circuit suddenly changes from a low level to a high level signal, or when the first high-voltage MOS tube and the second high-voltage MOS tube are turned on, the first voltage regulator diode and the second voltage regulator diode reversely break down, and the level at the R end or the S end of the RS trigger is clamped at VHB-Vz (Vz is the reverse breakdown voltage value of the voltage regulator diode). When the signal level at the HS end of the circuit suddenly changes from a high level to a low level signal, the first voltage zener diode and the second voltage zener diode will both be forward-conducted, clamping the levels of the R and S ends of the RS trigger at VHB+Vbe (Vbe is the forward conduction voltage value of the voltage zener diode). Thus, the first and second voltage zener diodes can well ensure that the circuits at the R and S ends of the RS trigger operate within a safe voltage range. The circuit cost added by the solution of the present invention is very low, but it completely solves the interference problem of the half-bridge drive circuit that controls LLC resonance, and at the same time ensures that the circuit components operate within a safe voltage range. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The invention is an existing half-bridge driving circuit for controlling LLC resonance.

[0013] Figure 2 The output signal waveform diagram of the existing half-bridge driving circuit for controlling LLC resonance.

[0014] Figure 3 The invention provides an anti-interference half-bridge driving circuit for controlling LLC resonance.

[0015] Figure 4 The waveform diagrams of various signals when the anti-interference half-bridge driving circuit for controlling LLC resonance proposed by the present invention is not introduced into the first MOS tube.

[0016] Figure 5 The waveform diagrams of various signals when the first MOS tube is introduced into the anti-interference half-bridge driving circuit for controlling LLC resonance proposed by the present invention. DETAILED DESCRIPTION

[0017] In order to deepen the understanding and recognition of the present invention, the present invention is further described and introduced below in conjunction with the accompanying drawings.

[0018] like Figure 3 As shown, an anti-interference half-bridge driving circuit for controlling LLC resonance includes a pulse generator 101, first and second high-voltage MOS tubes, first to third MOS tubes, first and second resistors, RS triggers, first and second voltage regulator diodes, the input end of the pulse generator 101 inputs a square wave signal, the output end of the pulse generator 101 is respectively connected to the gates of the first and second high-voltage MOS tubes, the sources of the first and second high-voltage MOS tubes are grounded, the drains of the first and second high-voltage MOS tubes are respectively connected to one end of the first and second resistors, the other ends of the first and second resistors are led out as a power supply for the half-bridge high-side circuit, the HB end is led out as the HB end, the drain of the first MOS tube 106 is connected to the drain of the first high-voltage MOS tube 102 and the first The gate of the first MOS transistor 106 is connected between the drain of the second high-voltage MOS transistor 103 and the second resistor 105, the source of the first MOS transistor 106 is connected between the first and second resistors, the anode of the first voltage regulator diode 107 is connected between the drain of the first high-voltage MOS transistor 102 and the first resistor 104, the anode of the second voltage regulator diode 108 is connected between the drain of the second high-voltage MOS transistor 103 and the second resistor 105, the cathodes of the first and second voltage regulator diodes are both connected to the HB terminal, the S terminal of the RS trigger is connected to the anode of the first voltage regulator diode 107, the R terminal of the RS trigger is connected to the anode of the second voltage regulator diode 108, and the output terminal of the RS trigger is connected to the input terminal of the output pre-driving circuit 110. When the R terminal is at a low level, the RS trigger outputs a high level, and when the R terminal is at a high level and the S terminal is at a low level, the RS trigger outputs a low level. The output end of the output pre-driving circuit 110 is connected to the gates of the second and third MOS transistors, the drain of the second MOS transistor 111 is connected to the drain of the third MOS transistor 112, the source of the second MOS transistor 111 is connected to the HB end, the source of the third MOS transistor 112 is led out as the HS end of the circuit, and the common end of the gates of the second and third MOS transistors is led out as the HO end of the circuit.

[0019] When the above circuit is working, a square wave signal is used as the input signal IN. After passing through the pulse generator 101, a pulse is generated at the rising edge and the falling edge of the square wave signal, which are respectively used to drive the first high-voltage MOS transistor 102 and the second high-voltage MOS transistor 103, and generate a pulse wave with an anti-phase on the first resistor 104 and the second resistor 105. After the anti-phase pulse wave is transmitted to the RS trigger, a square wave signal with the same phase as the input square wave signal is restored at the HO end of the circuit.

[0020] The output pre-driving circuit 110 has the function of strengthening the driving signal output by the RS trigger and controlling the dead time. Specifically, a multi-stage signal amplification driving circuit connected in series can be used to gradually strengthen the driving signal.

[0021] Preferably, the first and second high-voltage MOS tubes are high-voltage NMOS tubes.

[0022] Further preferably, the first MOS tube 106 is a PMOS tube.

[0023] Further preferably, the second MOS tube 111 is a PMOS tube, and the third MOS tube 112 is an NMOS tube.

[0024] Further preferably, the first and second resistors are implemented by resistors.

[0025] like Figure 4 As shown, when the signal level at the HS end of the circuit suddenly changes from a low level to a high level, without introducing the first MOS tube 106, the signals at the R and S ends of the RS trigger cannot respond quickly, so that both the R and S ends will generate negative pulse interference signals, wherein the negative pulse signal at the S end causes the signal waveform output from the HO end to be incorrectly flipped in some cases.

[0026] After the first MOS transistor 106 is introduced into the present circuit, when the signal level at the HS end of the circuit changes from a low level to a high level signal, the undershoot signal at the R end of the RS trigger will turn on the first MOS transistor 106 to clamp the level at the S end at a high level, and the undershoot signal at the R end will not cause the signal output from the HO end to malfunction. The corresponding signal waveforms are as follows: Figure 5 As shown, it can be seen that the clamping effect of the first MOS tube 106 on the S-terminal level of the RS trigger greatly improves the anti-interference ability of the half-bridge driving circuit.

[0027] At the same time, the first voltage zener diode 107 and the second voltage zener diode 108 are introduced in the present circuit. When the signal level at the HS end of the circuit suddenly changes from a low level to a high level signal, or when the first high-voltage MOS tube 102 and the second high-voltage MOS tube 103 are turned on, the first voltage zener diode 107 and the second voltage zener diode 108 reversely break down, and the level at the R end or the S end of the RS trigger is clamped at VHB-Vz (Vz is the reverse breakdown voltage value of the voltage zener diode). When the signal level at the HS end of the circuit suddenly changes from a high level to a low level signal, the first voltage zener diode 107 and the second voltage zener diode 108 will be forward-conducted, and the level at the R end and the S end of the RS trigger will be clamped at VHB+Vbe (Vbe is the forward conduction voltage value of the voltage zener diode). In the present circuit, by means of this measure, the circuits at the R and S ends of the RS trigger can be well ensured to operate within a safe voltage range.

[0028] The half-bridge drive circuit proposed in the present invention has a simple structure, and only introduces one PMOS tube and two voltage-stabilizing diodes into the circuit. The increased circuit cost is very low, but it completely solves the interference problem of the half-bridge drive circuit that controls LLC resonance, while ensuring that the circuit devices operate within a safe voltage range.

[0029] The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes composed of any combination of the above-mentioned technical features. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. An anti-interference half-bridge drive circuit for controlling LLC resonance, comprising a pulse generator, a first high-voltage MOS transistor, a second high-voltage MOS transistor, a first MOS transistor, a second MOS transistor, a third MOS transistor, a first resistor, a second resistor, an RS trigger, a first zener diode, and a second zener diode. The input end of the pulse generator inputs a square wave signal, the output end of the pulse generator is connected to the gate of the first high-voltage MOS transistor and the gate of the second high-voltage MOS transistor respectively, the source of the first high-voltage MOS transistor and the source of the second high-voltage MOS transistor are grounded, the drain of the first high-voltage MOS transistor is connected to one end of the first resistor, the drain of the second high-voltage MOS transistor is connected to one end of the second resistor, the other end of the first resistor and the other end of the second resistor are led to form the HB end of the half-bridge high-side circuit and connected to a power supply, the drain of the first MOS transistor is connected between the drain of the first high-voltage MOS transistor and the first resistor, the gate of the first MOS transistor is connected between the drain of the second high-voltage MOS transistor and the second resistor, the source of the first MOS transistor is connected between the first resistor and the second resistor, the anode of the first zener diode is connected between the drain of the first high-voltage MOS transistor and the first resistor, and the anode of the second zener diode is connected between the drain of the first high-voltage MOS transistor and the first resistor. The circuit is connected between the drain of the second high-voltage MOS transistor and the second resistor, the cathode of the first zener diode and the cathode of the second zener diode are both connected to the HB terminal, the S terminal of the RS trigger is connected to the anode of the first zener diode, the R terminal of the RS trigger is connected to the anode of the second zener diode, the output terminal of the RS trigger is connected to the input terminal of the output pre-driver circuit, the output terminal of the output pre-driver circuit is connected to the gate of the second MOS transistor and the gate of the third MOS transistor, the drain of the second MOS transistor is connected to the drain of the third MOS transistor, the source of the second MOS transistor is connected to the HB terminal, the source of the third MOS transistor is led to serve as the HS terminal of the half-bridge high-side circuit, and the common terminal of the drains of the second MOS transistor and the third MOS transistor is led to serve as the HO terminal of the half-bridge high-side circuit; the first and second high-voltage MOS transistors are high-voltage NMOS transistors, and the first MOS transistor is a PMOS transistor; when the signal level of the HS terminal suddenly changes from a low-level signal to a high-level signal, the undershoot signal at the R terminal of the RS trigger will turn on the first MOS transistor and clamp the level of the S terminal of the RS trigger to a high level, so that the undershoot signal at the R terminal of the RS trigger will not cause the signal output from the HO terminal to malfunction.

2. The anti-interference half-bridge driving circuit for controlling LLC resonance according to claim 1, characterized in that: The second MOS tube is a PMOS tube, and the third MOS tube is an NMOS tube.

3. The anti-interference half-bridge driving circuit for controlling LLC resonance according to claim 2, characterized in that: The first resistor and the second resistor are implemented by resistors.

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