CN-115149815-B - Drive control circuit and drive control method thereof

CN115149815BCN 115149815 BCN115149815 BCN 115149815BCN-115149815-B

Abstract

The invention relates to the field of switching power supplies, in particular to a driving control circuit adopting transformer isolation and a driving control method thereof. The driving control method of the driving control circuit comprises the steps of demagnetizing the isolation transformer through the first demagnetizing unit when a PWM signal input to the control circuit is at a high level, and demagnetizing the isolation transformer through the second demagnetizing unit when the PWM signal input to the control circuit is at a low level. The invention can improve the large current driving capability, increase the demagnetizing voltage of the isolation transformer and keep the normally open function of the continuous conduction of the power switch device.

Inventors

XUE ZEYU
JIA YUFENG
ZHOU YU

Assignees

广州金升阳科技有限公司

Dates

Publication Date: 20260512
Application Date: 20220625

Claims (8)

1. The driving control circuit comprises an edge modulation circuit and an isolation transformer connected with the edge modulation circuit, wherein the edge modulation circuit comprises a control circuit, a driving circuit and a full-bridge unit, the full-bridge unit is provided with a switching tube S1, a switching tube S2, a switching tube S3 and a switching tube S4, a source electrode of the switching tube S1 is respectively connected with a drain electrode of the switching tube S2 and a first end of a primary winding of the isolation transformer, a source electrode of the switching tube S3 is respectively connected with a drain electrode of the switching tube S4 and a second end of the primary winding of the isolation transformer, a drain electrode of the switching tube S1 and a drain electrode of the switching tube S3 are respectively connected with an anode of a power supply, and a source electrode of the switching tube S2 and a source electrode of the switching tube S4 are respectively connected with a cathode of the power supply; the first demagnetization unit comprises a diode D2, a switching tube S4 and a switching tube S6, wherein the diode D2 and the switching tube S6 are connected in series and then connected in parallel with the drain electrode and the grid electrode of the switching tube S4; The second demagnetization unit comprises a diode D1, a switching tube S2, a switching tube S4 and a switching tube S5, wherein the diode D1 and the switching tube S5 are connected in series and then connected in parallel with the drain electrode and the grid electrode of the switching tube S2; When the PWM signal input to the control circuit is at a high level, demagnetizing the isolation transformer through the first demagnetizing unit; and when the PWM signal input to the control circuit is at a low level, the isolation transformer is demagnetized through the second demagnetizing unit.
2. The drive control circuit according to claim 1, wherein the anode of the diode D2 is connected with the drain of the switching tube S4 and the first end of the primary winding of the isolation transformer, the cathode of the diode D2 is connected with the drain of the switching tube S6, and the source of the switching tube S6 is connected with the gate of the switching tube S4, the drain of the switching tube S2 is connected with the second end of the primary winding of the isolation transformer, and the source of the switching tube S2 is connected with the negative electrode of the power supply; The positive pole of diode D1 with the drain electrode of switch tube S2 with the second end of isolation transformer 'S primary winding is connected, diode D1' S negative pole respectively with the drain electrode of switch tube S5, the source of switch tube S5 with the grid of switch tube S2 is connected, the drain electrode of switch tube S4 is connected the first end of isolation transformer primary winding.
3. The driving control circuit according to claim 2, wherein the first demagnetization unit is configured to demagnetize the isolation transformer when the PWM signal input to the control circuit is at a high level, the demagnetization process specifically includes that the switching tube S6 is turned on, a demagnetization current flows from a first end of a primary winding of the isolation transformer, passes through the diode D2, the switching tube S6, a gate-source parasitic capacitance of the switching tube S4, and a body diode of the switching tube S2, and returns to a second end of a primary winding of the isolation transformer to charge the gate-source parasitic capacitance of the switching tube S4, and when a gate voltage of the switching tube S4 reaches a turn-on threshold, the switching tube S4 is turned on, and then the demagnetization current flows from the first end of the primary winding of the isolation transformer, sequentially passes through the switching tube S4 and the body diode of the switching tube S2, and returns to the second end of the primary winding of the isolation transformer; The second demagnetization unit is configured to demagnetize the isolation transformer when the PWM signal input to the control circuit is at a low level, and the demagnetization process specifically includes that the switching tube S5 is turned on, the demagnetization current flows out from the second end of the primary winding of the isolation transformer, first passes through the diode D1, the switching tube S5, the gate-source parasitic capacitance of the switching tube S2 and the body diode of the switching tube S4, then returns to the first end of the primary winding of the isolation transformer, charges the gate-source parasitic capacitance of the switching tube S2, when the gate voltage of the switching tube S2 reaches the turn-on threshold, the switching tube S2 is turned on, and then the demagnetization current flows out from the second end of the primary winding of the isolation transformer, sequentially passes through the switching tube S2 and the body diode of the switching tube S4, and then returns to the first end of the primary winding of the isolation transformer.
4. The driving control circuit according to claim 1, further comprising a resistor R1 and a resistor R2, wherein one end of the resistor R2 is connected to the gate of the switching tube S4, the other end is connected to the source of the switching tube S4, and one end of the resistor R1 is connected to the gate of the switching tube S2, and the other end is connected to the source of the switching tube S2.
5. The drive control circuit according to claim 1, wherein the first demagnetization unit demagnetizes the isolation transformer, and specifically comprises two stages: The first stage, in which the switching tube S6 is turned on, the switching tube S2 is turned off, and the demagnetizing current flowing out from the first end of the primary winding of the isolation transformer charges the parasitic capacitance of the gate and the source of the switching tube S4 through the diode D2 and the switching tube S6; And in the second stage, when the voltage of the gate-source parasitic capacitance of the switching tube S4 reaches the conduction threshold value of the switching tube S4, the switch tube S4 is conducted, the demagnetizing current flows out from the first end of the primary winding of the isolation transformer, sequentially passes through the switching tube S4 and the body diode of the switching tube S2, and returns to the second end of the primary winding of the isolation transformer.
6. The drive control circuit according to claim 1, wherein the demagnetization of the isolation transformer by the second demagnetization unit comprises two stages: The first stage, in which the switching tube S5 is turned on, the switching tube S4 is turned off, and the demagnetizing current flowing out from the second end of the primary winding of the isolation transformer charges the parasitic capacitance of the gate and the source of the switching tube S2 through the diode D1 and the switching tube S5; And in the second stage, when the voltage of the parasitic capacitance of the gate and the source of the switch tube S2 reaches the conduction threshold value of the switch tube S2, the switch tube S2 is conducted, the demagnetizing current flows out from the second end of the primary winding of the isolation transformer, sequentially passes through the switch tube S2 and the body diode of the switch tube S4, and returns to the first end of the primary winding of the isolation transformer.
7. The driving control circuit comprises an edge modulation circuit and an isolation transformer connected with the edge modulation circuit, wherein the edge modulation circuit comprises a control circuit, a driving circuit and a full-bridge unit, the full-bridge unit comprises a switching tube S1, a switching tube S2, a switching tube S3 and a switching tube S4, a source electrode of the switching tube S3 is respectively connected with a drain electrode of the switching tube S4 and a first end of a primary winding of the isolation transformer, a source electrode of the switching tube S1 is respectively connected with a drain electrode of the switching tube S2 and a second end of the primary winding of the isolation transformer, a drain electrode of the switching tube S1 and a drain electrode of the switching tube S3 are respectively connected with an anode of a power supply, and a source electrode of the switching tube S2 and a source electrode of the switching tube S4 are respectively connected with a cathode of the power supply; the first demagnetization unit comprises a diode D2, a switching tube S6, a switching tube S4, a switching tube S10 and a switching tube S2, wherein the diode D2 and the switching tube S6 are connected in series and then connected in parallel with the drain electrode and the grid electrode of the switching tube S4, the drain electrode of the switching tube S10 is connected with the grid electrode of the switching tube S4, and the source electrode of the switching tube S10 is connected with the source electrode of the switching tube S4; The second demagnetization unit comprises a diode D1, a switching tube S5, a switching tube S2, a switching tube S8 and a switching tube S4, wherein the diode D1 and the switching tube S5 are connected in series and then connected in parallel with the drain electrode and the grid electrode of the switching tube S2, the drain electrode of the switching tube S8 is connected with the grid electrode of the switching tube S2, and the source electrode of the switching tube S8 is connected with the source electrode of the switching tube S2; When the PWM signal input to the control circuit is at a high level, demagnetizing the isolation transformer through the first demagnetizing unit; and when the PWM signal input to the control circuit is at a low level, the isolation transformer is demagnetized through the second demagnetizing unit.
8. The drive control circuit according to claim 7, further comprising a switching tube S7 and a switching tube S9, wherein a drain electrode of the switching tube S7 is connected to the positive electrode of the power supply, a source electrode of the switching tube S7 is connected to the gate electrode of the switching tube S2, a drain electrode of the switching tube S9 is connected to the positive electrode of the power supply, and a source electrode of the switching tube S9 is connected to the gate electrode of the switching tube S4.

Description

Drive control circuit and drive control method thereof Technical Field The invention relates to the field of switching power supplies, in particular to a driving control circuit adopting transformer isolation and a driving control method thereof. Background Compared with a linear power supply, the switching power supply has the characteristics of small volume, high efficiency, high power, strong anti-interference performance and the like, is widely applied to the fields of automobiles, photovoltaics, industrial control, medical treatment, handheld equipment and the like, along with the continuous iteration of technology, the switching power supply is developing towards high frequency, high power, small volume and the like, and MOSFETs, insulated Gate Bipolar Transistors (IGBTs) and the like have excellent performance at higher frequency, so the switching power supply is used as power switching devices of power stages in the switching power supply, and as is well known, each power switching device needs a driving circuit, the switching power supply has different topological structures in different applications, the driving mode is determined by the positions of the power switching devices in the different topological structures, and at present, two modes are adopted for driving the power switching devices, namely non-isolated direct driving and isolated floating driving. The existing isolation driving is three, namely a bootstrap driving, a transformer isolation driving and a driving power supply and a combined driver, wherein the bootstrap driving is an optimal driving scheme applied to bridge topology, but is limited by isolation withstand voltage of the bootstrap driving, and can only be applied to conventional occasions, and the bootstrap driving cannot be directly used when the bootstrap driving exceeds 1kV or is not applied to bridge topology, so that the bootstrap driving has certain limitation; the scheme of using the drive power source and the driver has high cost and large volume, and is suitable for occasions which are driven by high power and insensitive to volume and cost; the transformer isolation driving is a scheme which is suitable for a full scene and has a cost and volume comparison compromise, the traditional transformer isolation driving adopts an asymmetric half-bridge framework, and capacitors are arranged on primary and secondary sides, so that the transformer is always in an excitation state and a demagnetization state when a duty ratio signal is transmitted, and the inductance is increased to reduce excitation current, so that loss is reduced, the brought disadvantages are that the volume is large, and in addition, when the transmitted duty ratio is too large or abrupt change occurs, the voltage of the secondary side capacitor cannot be abrupt change, so that the problem that a power switch tube is damaged by continuous high level occurs at an output end. Solving this problem requires adding secondary side capacitor discharge circuitry, further increasing cost and bulk. In order to solve the problems of volume, cost and reliability of the traditional transformer isolation driving, a new driving control method and a driving control circuit are proposed in the chinese patent application with publication number CN113193735A, referring to fig. 1, the rising edge of an input signal is modulated into a positive pulse with a fixed pulse width by an edge modulation circuit in the driving control circuit, the falling edge of the input signal is modulated into a negative pulse with a fixed pulse width, and in the state that the input signal is continuously high level, a plurality of continuous positive pulses are generated at a certain period by an energy supplementing circuit, and then transmitted to a secondary side by an isolation transformer, the secondary side circuit demodulates the corresponding first positive pulse into the rising edge of the secondary side driving, demodulates the corresponding first negative pulse into the falling edge of the secondary side driving, and the continuous positive pulse is used for supplementing energy to a driven power tube to maintain the voltage required for conducting, thereby reducing the input signal and solving the problem of continuous conducting, and simultaneously, the problem of discontinuous driving of the low-frequency motor is also improved. But this solution has the following limitations: The key factor of the scheme affecting the driving capability is the pulse width ratio, wherein the higher the pulse width ratio is, the more energy is transferred and the stronger the driving capability is, and the pulse width ratio is the proportion of the pulse duration to the whole switching period. According to the modulation principle, referring to fig. 2, 100 in fig. 2 is an internal block diagram of the edge modulation circuit in fig. 1, and the excitation process of the scheme is that, taking positive pulse as an example, when the first bridge a