Totem pole PFC circuit and short circuit protection circuit used therein

Abstract

The invention provides a totem pole PFC (Power Factor Correction) circuit and a short-circuit protection circuit used in the totem pole PFC circuit. The totem-pole PFC circuit comprises a high-frequency bridge arm, a zero-crossing current detection resistor and an output capacitor. When an upper arm high-speed tube or a lower arm high-speed tube of the high-frequency bridge arm is short-circuited, a discharge loop of the output capacitor is an upper pole plate-gt of the output capacitor; an upper arm high-speed tube-gt; a lower arm high-speed tube-gt; a zero-crossing current detection resistor-gt; and a lower plate of the output capacitor. The short-circuit protection circuit is configured to generate a high-frequency bridge arm short-circuit protection signal used for disconnecting a main power line of the totem pole PFC circuit when the absolute amplitude of the voltage on the zero-crossing current detection resistor is smaller than a high-frequency bridge arm short-circuit protection threshold value.

Description

Technical Field

[0001] The present invention generally relates to the field of circuits, and more particularly to a totem pole power factor correction (PFC) circuit and a short-circuit protection circuit used therein. Background Art

[0002] PFC circuits are primarily used to control the input current waveform so that it synchronizes with the input voltage waveform to improve the power factor and reduce harmonic content. PFC circuits can be divided into passive and active PFC circuits. Passive PFC circuits include inductor-compensated PFC circuits and valley-filling PFC circuits. Inductor-compensated PFC circuits work by using an inductor to reduce the phase difference between the fundamental current and voltage of the AC input, thereby improving the power factor. Valley-filling PFC circuits work by using a valley-filling circuit after the rectifier bridge to increase the conduction angle of the rectifier tube, thereby filling the valley point and transforming the input current from a spike pulse to a waveform close to a sine wave. Active PFC circuits work by using a dedicated control chip to adjust the current waveform, compensating for the phase difference between the input current and input voltage, thereby improving the power factor. Summary of the Invention

[0003] According to an embodiment of the present invention, a short-circuit protection circuit for a totem-pole PFC circuit includes a high-frequency bridge arm, a zero-current detection resistor, and an output capacitor. When an upper high-speed transistor or a lower high-speed transistor of the high-frequency bridge arm short-circuits during demagnetization of the PFC inductor, a discharge path of the output capacitor follows the sequence: upper plate of the output capacitor, upper high-speed transistor, lower high-speed transistor, zero-current detection resistor, and lower plate of the output capacitor. The short-circuit protection circuit is configured to generate a high-frequency bridge arm short-circuit protection signal for disconnecting a main power line of the totem-pole PFC circuit when the absolute amplitude of the voltage across the zero-current detection resistor is less than a high-frequency bridge arm short-circuit protection threshold.

[0004] According to an embodiment of the present invention, a short-circuit protection circuit for a totem-pole PFC circuit includes a PFC inductor. The short-circuit protection circuit is configured to generate a PFC inductor short-circuit protection signal for disconnecting a main power line of the totem-pole PFC circuit when the absolute magnitude or amplitude of the induced voltage on an auxiliary winding of the PFC inductor during a positive half-cycle of an AC power source is less than a first inductor short-circuit protection threshold, or when the absolute magnitude or amplitude of the induced voltage on an auxiliary winding of the PFC inductor during a negative half-cycle of the AC power source is less than a second inductor short-circuit protection threshold.

[0005] A totem pole PFC circuit according to an embodiment of the present invention includes the above-mentioned short-circuit protection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The present invention can be better understood from the following description of specific embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0007] Figure 1 A schematic block diagram shows a system topology structure of a totem pole PFC circuit according to an embodiment of the present invention.

[0008] Figure 2 Shown Figure 1 The diagram shows the discharge loop of the output capacitor in the totem pole PFC circuit during normal discharge and when current reverse flow occurs due to an accident.

[0009] Figure 3 Shown for Figure 1 The schematic diagram of the short-circuit protection circuit of the totem pole PFC circuit is shown.

[0010] Figure 4 Shown Figure 3 The schematic block diagram of an example logical structure of a PFC inductor short-circuit protection circuit is shown.

[0011] Figure 5 Shown in Figure 1 The totem pole PFC circuit shown is working properly Figure 4 Example waveforms of multiple signals in the short-circuit protection circuit shown.

[0012] Figure 6 Shown Figure 3 FIG. 1 is a schematic block diagram of another example logic structure of a PFC inductor short-circuit protection circuit.

[0013] Figure 7 Shown Figure 6 The figure shows a schematic block diagram of an example logic structure of an inductive short-circuit protection logic control and timing module.

[0014] Figure 8 Shown Figure 3 FIG. 1 is a schematic block diagram of another example logic structure of a PFC inductor short-circuit protection circuit.

[0015] Figure 9 Shown Figure 8 The figure shows a schematic block diagram of an example logic structure of an inductive short-circuit protection logic control and timing module.

[0016] Figure 10 Shown Figure 3 The schematic block diagram of an example logical structure of a high-frequency bridge arm short-circuit protection circuit is shown. DETAILED DESCRIPTION

[0017] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed in order to provide a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is by no means limited to any specific configuration and algorithm proposed below, but covers any modification, replacement and improvement of elements, components and algorithms without departing from the spirit of the present invention. In the accompanying drawings and the following description, well-known structures and technologies are not shown in order to avoid unnecessary ambiguity in the present invention. In addition, it should be noted that the term "A is connected to B" used herein can mean "A is directly connected to B" or "A is indirectly connected to B via one or more other elements."

[0018] Figure 1 FIG. 1 is a schematic block diagram showing a system topology structure of a totem pole PFC circuit according to an embodiment of the present invention. Figure 1 As shown, the totem pole PFC circuit 100 includes an AC power supply AC, a PFC inductor L, an industrial frequency bridge arm composed of an upper arm low-speed tube SRH and a lower arm low-speed tube SRL, a high-frequency bridge arm composed of an upper arm high-speed tube PWMH and a lower arm high-speed tube PWML, a PFC control chip 102, an output capacitor C, and a zero-crossing current detection resistor R. ZCD , and a resistive load Rload, wherein the upper arm low-speed tube SRH, the lower arm low-speed tube SRL, the upper arm high-speed tube PWMH, and the lower arm high-speed tube PWMH can all be implemented by power tubes (for example, metal oxide semiconductor (MOS) field effect transistors, MOS tubes for short), and the control signals for controlling their conduction and shutdown all come from the PFC control chip 102.

[0019] In the positive half cycle of the AC power supply AC (i.e., the AC input voltage V AC During the period (where the voltage is positive), the working process of the totem pole PFC circuit 100 includes: when the upper arm low-speed tube SRH and the upper arm high-speed tube PWMH are in the off state and the lower arm low-speed tube SRL and the lower arm high-speed tube PWML are in the on state, the PFC inductor L is magnetized; when the upper arm low-speed tube SRH remains in the off state, the lower arm low-speed tube SRL remains in the on state, the upper arm high-speed tube PWMH changes from the off state to the on state, and the lower arm high-speed tube PWML changes from the on state to the off state, the voltage generated by the demagnetization of the PFC inductor L is superimposed on the AC input voltage V AC The system output voltage Vo is provided, wherein the lower arm high-speed tube PWML magnetizes the PFC inductor L with a duty cycle D (D<1), and the upper arm high-speed tube PWMH demagnetizes the PFC inductor L with a duty cycle (1-D).

[0020] In the negative half cycle of the AC power supply AC (i.e., the AC input voltage V AC During the period (where the voltage is negative), the operation process of the totem pole PFC circuit 100 includes: when the upper arm low-speed tube SRH and the upper arm high-speed tube PWMH are in the on state and the lower arm low-speed tube SRL and the lower arm high-speed tube PWML are in the off state, the PFC inductor L is magnetized; when the upper arm low-speed tube SRH remains in the on state and the lower arm low-speed tube SRL remains in the off state, the upper arm high-speed tube PWMH changes from the on state to the off state, and the lower arm high-speed tube PWML changes from the off state to the on state, the voltage generated by the demagnetization of the PFC inductor L is superimposed on the AC input voltage V AC Provides system output voltage Vo.

[0021] like Figure 1 As shown, the system output voltage Vo on the output capacitor C is fed back to the output voltage feedback pin FB of the PFC control chip 102 after being divided by resistors. The lower plate of the output capacitor C is connected to the zero-crossing current detection pin ZCD of the PFC control chip 102. The auxiliary winding of the PFC inductor L is connected to the auxiliary winding connection pin AUX of the PFC control chip 102. One end of the auxiliary winding connection pin AUX of the PFC control chip 102 is the opposite end of the output winding of the PFC inductor L. Therefore, the inductive inductance V on the auxiliary winding of the PFC inductor L is AUX There is a certain proportional relationship between it and the input line voltage Vin.

[0022] When the PFC inductor L is magnetized during the positive half cycle of the AC power supply AC or demagnetized during the negative half cycle of the AC power supply AC, the induced voltage V on the auxiliary winding of the PFC inductor L is AUX It can be expressed as:

[0023]

[0024] When the PF inductor L is magnetized during the negative half cycle of the AC power supply AC or demagnetized during the positive half cycle of the AC power supply AC, the induced voltage V on the auxiliary winding of the PFC inductor L is AUX It can be expressed as:

[0025]

[0026] Wherein, Ns is the number of turns of the output winding of the PFC inductor L, and Naux is the number of turns of the auxiliary winding of the PFC inductor L.

[0027] As shown in equations (1) and (2), the induced voltage V on the auxiliary winding of the PFC inductor L is AUX The condition of at least one of the input line voltage Vin and the system output voltage Vo of the totem pole PFC circuit 100 may be reflected.

[0028] When the totem pole PFC circuit 100 operates normally in the positive half cycle of the AC power supply AC, the upper arm low-speed tube SRH is in the off state and the lower arm low-speed tube SRL is in the on state. When the upper arm high-speed tube PWMH is in the off state and the lower arm high-speed tube PWML is in the on state, the AC power supply AC magnetizes the PFC inductor L, and the induced voltage V on the auxiliary winding of the PFC inductor L is AUX When the upper arm high-speed tube PWMH is in the on state and the lower arm high-speed tube PWML is in the off state, the AC power supply AC demagnetizes the PFC inductor L, and the induced voltage V on the auxiliary winding of the PFC inductor L is AUX is a positive voltage.

[0029] When the totem pole PFC circuit 100 operates normally in the negative half cycle of the AC power supply AC, the upper arm low-speed tube SRH is in the on state and the lower arm low-speed tube SRL is in the off state. When the upper arm high-speed tube PWMH is in the on state and the lower arm high-speed tube PWML is in the off state, the AC power supply AC magnetizes the PFC inductor L, and the induced voltage V on the auxiliary winding of the PFC inductor L is AUX When the upper arm high-speed tube PWMH is in the off state and the lower arm high-speed tube PWML is in the on state, the AC power supply AC demagnetizes the PFC inductor L, and the induced voltage V on the auxiliary winding of the PFC inductor L is AUX is a negative voltage.

[0030] When the PFC inductor L is short-circuited due to an abnormal circuit condition caused by some unexpected situation, the totem pole PFC circuit 100 loses its inductance characteristics, which causes a large current to appear in the totem pole PFC circuit 100, and the induced voltage V on the auxiliary winding of the PFC inductor L is AUX The normal negative voltage amplitude will not be achieved during the positive half-cycle of the AC power source AC, and the normal positive voltage amplitude will not be achieved during the negative half-cycle of the AC power source AC. Because the power transistors that make up the high-frequency bridge arm serve as both switches for magnetizing the PFC inductor L and synchronous rectifiers that provide a current path during demagnetization of the PFC inductor L, the high current caused by a short circuit in the PFC inductor L may break down the power transistors, causing the totem pole PFC circuit 100 to malfunction or even burn out the PFC control chip 102.

[0031] Figure 2 Shown Figure 1 The diagram below shows the discharge circuit of the output capacitor in the totem pole PFC circuit during normal discharge and when current backflow occurs due to an accident. Figure 2As shown, during normal operation of the totem-pole PFC circuit 100, when the PFC inductor L is demagnetized, the output capacitor C is charged, and the system output voltage Vo is the voltage generated by the demagnetization of the PFC inductor L. When the PFC inductor L is magnetized, the output capacitor C and the resistive load Rload form a loop, and the system output voltage Vo is the voltage generated by the discharge of the output capacitor C. If the totem-pole PFC circuit 100 is affected by some unexpected situation, causing the upper arm or lower arm high-speed transistor of the high-frequency bridge arm to short-circuit, the output capacitor C discharges in the non-output loop, generating a reverse current Iinrush. The discharge path of the output capacitor C is from the upper plate of the output capacitor C -> the upper arm high-speed transistor PWMH -> the lower arm high-speed transistor PWML -> the zero-crossing current detection resistor R ZCD ->The lower plate of the output capacitor C, at this time the zero current detection resistor R ZCD The voltage on the output capacitor C is negative. Current backflow will cause significant fluctuations in the load current Io flowing through the resistive load Rload and the system output voltage Vo. At the same time, if a large amount of charge accumulates on the output capacitor C, the system output voltage Vo on the output capacitor C will exceed the tolerance range of the power transistor in the high-frequency bridge arm. This may cause malfunctions in the totem-pole PFC circuit 100 and damage circuit stability and performance.

[0032] In view of the above problems, a short-circuit protection circuit for a totem-pole PFC circuit 100 according to an embodiment of the present invention is proposed. The short-circuit protection circuit can detect whether a short circuit occurs in the PFC inductor L in the totem-pole PFC circuit 100 and effectively protect the PFC control chip 102 in the totem-pole PFC circuit 100 when a short circuit occurs in the PFC inductor L. This circuit ultimately eliminates damage to the PFC control chip 102 caused by a short circuit in the PFC inductor L and / or prevents current backflow caused by a short circuit in a power transistor of a high-frequency bridge arm in the totem-pole PFC circuit 100. This circuit better ensures that the totem-pole PFC circuit 100 correctly executes its logical functions, thereby enhancing the reliability and stability of the totem-pole PFC circuit 100.

[0033] Figure 3 Shown for Figure 1 Schematic block diagram of the short circuit protection circuit of the totem pole PFC circuit 100 shown in FIG. Figure 3 As shown, in some embodiments, the short-circuit protection circuit for the totem pole PFC circuit 100 can be implemented in the PFC control chip 102 and can include a PFC inductor short-circuit protection circuit 302 and a high-frequency bridge arm short-circuit protection circuit 304, wherein: the PFC inductor short-circuit protection circuit 302 detects the induced voltage V on the auxiliary winding of the PFC inductor L via the auxiliary winding connection pin AUX of the PFC control chip 102 AUX , and is configured as the induced voltage V on the auxiliary winding of the PFC inductor L AUXWhen the absolute amplitude or amplitude during the positive half cycle of the AC power source AC is less than the first inductor short circuit protection threshold or when the absolute amplitude or amplitude during the negative half cycle of the AC power source AC is less than the second inductor short circuit protection threshold, a PFC inductor short circuit protection signal for disconnecting the main power line of the totem pole PFC circuit 100 is generated; the high-frequency bridge arm short circuit protection circuit 304 detects the zero current detection resistor R through the zero current detection pin ZCD of the PFC control chip 102. ZCD voltage on the resistor R ZCD When the absolute amplitude of the voltage on the auxiliary winding of the PFC inductor L is less than the high-frequency bridge arm short-circuit protection threshold, a high-frequency bridge arm short-circuit protection signal is generated for disconnecting the main power line of the totem pole PFC circuit 100. Here, the induced voltage V on the auxiliary winding of the PFC inductor L can be determined by processing methods including but not limited to comparison, clamping, equivalent replacement, etc. AUX Whether the absolute amplitude or amplitude during the positive half cycle of the AC power supply AC is less than the first inductor short circuit protection threshold, the induced voltage V on the auxiliary winding of the PFC inductor L AUX Whether the absolute amplitude or amplitude during the negative half cycle of the AC power supply AC is less than the second inductor short circuit protection threshold, and the zero current detection resistor R ZCD Check whether the absolute amplitude of the voltage on the bridge is less than the high-frequency bridge arm short-circuit protection threshold.

[0034] Figure 4 Shown Figure 3 The schematic block diagram of an example logic structure of a PFC inductor short-circuit protection circuit is shown in FIG. Figure 4 As shown, in some embodiments, due to the induced voltage V on the auxiliary winding when the PFC inductor L is magnetized, AUX The induced voltage V on the auxiliary winding when the PFC inductor L is demagnetized is negative during the positive half cycle of the AC power supply AC and positive during the negative half cycle of the AC power supply AC. AUX The voltage is positive during the positive half-cycle of the AC power source AC and negative during the negative half-cycle of the AC power source AC. Therefore, the PFC inductor short-circuit protection circuit 302 includes a positive voltage detection unit 3022, a negative voltage detection unit 3024, a first switch K1 connected between the positive voltage detection unit 3022 and the auxiliary winding connection pin AUX of the PFC control chip 102, and a second switch K2 connected between the negative voltage detection unit 3024 and the auxiliary winding connection pin AUX of the PFC control chip 102. The first switch K1 switches between an on state and an off state under the control of a positive cycle switch control signal Phc or a negative cycle switch control signal Nhc. The positive voltage detection unit 3022 is configured to detect the inductive voltage V on the auxiliary winding when the PFC inductor L is magnetized. AUXThe amplitude during the negative half cycle of the AC power supply or the induced voltage V on the auxiliary winding when the PFC inductor L is demagnetized AUX The amplitude during the positive half cycle of the AC power source AC is used to generate a PFC inductor short circuit protection signal; the second switch K2 switches between the on state and the off state under the control of the positive cycle switch control signal Phc or the negative switch control signal Nhc; the negative voltage detection unit 3024 is configured to detect the induced voltage V on the auxiliary winding when the PFC inductor L is magnetized. AUX The absolute amplitude during the positive half cycle of the AC power supply or the induced voltage V on the auxiliary winding when the PFC inductor L is demagnetized AUX The absolute amplitude during the negative half cycle of the AC power source is used to generate a PFC inductor short-circuit protection signal.

[0035] like Figure 4 As shown, the high-frequency bridge arm short-circuit protection circuit 304 does not need to distinguish between the positive half cycle and the negative half cycle of the AC power supply AC, and can detect the zero current detection resistor R in real time. ZCD The voltage on the zero current detection resistor R ZCD When the absolute amplitude of the voltage on the high-frequency bridge arm is less than the high-frequency bridge arm short-circuit protection threshold, a high-frequency bridge arm short-circuit protection signal is generated.

[0036] Figure 5 Shown in Figure 1 The totem pole PFC circuit 100 shown in FIG. Figure 3 The waveform diagram of multiple signals in the short-circuit protection circuit shown in FIG. AC Indicates AC input voltage; Phc indicates the voltage used for AC input voltage V AC When the voltage is positive, the corresponding switch is controlled to be in the on state and the AC input voltage V AC When the voltage is negative, the corresponding switch is in the off state. Nhc is the positive cycle switch control signal used for the AC input voltage V AC When the voltage is positive, the corresponding switch is controlled to be in the off state and the AC input voltage V AC When the voltage is negative, the corresponding switch is in the on state. PWM represents the pulse width modulation (PWM) signal used to control the magnetization and demagnetization of the PFC inductor L (i.e., the PWM signal used to control the on and off of the upper arm high-speed tube PWMH and the lower arm high-speed tube PWML). ZCD represents the zero-current detection resistor R ZCD AUX represents the induced voltage V on the PFC inductor L. AUX .

[0037] It should be noted that in order to better analyze the relationship between signal waveforms, Figure 5The PWM signal in the figure is a signal after frequency reduction processing. According to the working principle of the totem pole PFC circuit, when the PWM signal is high, the AC power supply AC magnetizes the PFC inductor L, and the induced voltage V on the PFC inductor L is AUX Less than 0; when the PWM signal is low, the AC power supply AC demagnetizes the PFC inductor L, and the induced voltage V on the PFC inductor L AUX Assume that the induced voltage V on the PFC inductor L is positive and remains stable for a period of time. AUX When the voltage becomes positive at time t1, the induced voltage V on the PFC inductor L AUX It can remain stable for a period of time after time t1, so the induced voltage V on the PFC inductor L can be obtained during this period of time. AUX The absolute amplitude or magnitude of the current can reflect the working condition of the PFC inductor L, so it can be used to decide whether to enable or disable the PFC inductor short-circuit protection function. In addition, during the demagnetization period of the PFC inductor L, for the loop of the high-frequency bridge arm and the output capacitor C, the current flows through the zero current detection resistor R ZCD Converted into voltage, the zero-crossing current detection resistor R can be collected at time t2 ZCD The voltage on the resistor R is processed to determine the zero current. ZCD The absolute magnitude of the voltage on the MOSFET determines whether the high-frequency bridge arm short-circuit protection function is enabled or disabled.

[0038] Figure 6 Shown Figure 3 FIG. 1 is a schematic block diagram of another example logic structure of a PFC inductor short-circuit protection circuit. Figure 6 As shown, in some embodiments, the PFC inductor short circuit protection circuit 302 can be configured to: detect the induced voltage V on the auxiliary winding when the PFC inductor L is demagnetized during the negative half cycle of the AC power source AC. AUX Perform negative voltage processing (for example, taking the absolute value, taking the opposite number, negative voltage clamping, etc.) to obtain the induced voltage V on the auxiliary winding when the PFC inductor L is demagnetized. AUX The absolute amplitude during the negative half cycle of the AC power supply │V AUX │; By demagnetizing the PFC inductor L, the induced voltage V on the auxiliary winding AUX The amplitude V during the positive half cycle of the AC power supply AUX Compare it with the first inductor short-circuit protection threshold Vref1 to generate a positive half-cycle short-circuit detection result signal; by calculating the induced voltage V on the auxiliary winding when the PFC inductor L is demagnetized AUX The absolute amplitude during the negative half cycle of the AC power supply │V AUX│Generate a negative half-cycle short-circuit detection result signal by comparing it with the second inductor short-circuit protection threshold Vref2; Generate a PFC inductor short-circuit detection result signal AUX_ZCD by performing a logical OR operation on the positive half-cycle short-circuit detection result signal and the negative half-cycle short-circuit detection result signal; and Generate a PFC inductor short-circuit protection signal by performing a logical operation and / or timing on the PFC inductor short-circuit detection signal AUX_ZCD.

[0039] Figure 7 Shown Figure 6 The schematic block diagram of the example logic structure of the inductor short circuit protection logic control and timing module is shown in FIG. Figure 7 As shown, in some embodiments, the PFC inductor short-circuit protection circuit 302 may be further configured to: generate a de-jittered PWM signal by delaying a signal portion of the PWM signal for controlling the magnetization and demagnetization of the PFC inductor L, which is used to control the demagnetization of the PFC inductor; generate a PFC inductor short-circuit determination signal by performing a logic operation and / or timing on the PFC inductor short-circuit detection signal AUX_ZCD; and generate a PFC inductor short-circuit protection signal by performing a logic AND operation on the de-jittered PWM signal and the PFC inductor short-circuit determination signal.

[0040] Figure 8 Shown Figure 3 FIG. 1 is a schematic block diagram of another example logic structure of a PFC inductor short-circuit protection circuit. Figure 8 As shown, in some embodiments, the PFC inductor short circuit protection circuit 302 can be configured to: detect the induced voltage V on the auxiliary winding when the PFC inductor L is magnetized during the positive half cycle of the AC power source AC. AUX Perform negative voltage processing (for example, taking the absolute value, taking the opposite number, negative voltage clamping, etc.) to obtain the induced voltage V on the auxiliary winding when the PFC inductor L is magnetized. AUX The absolute amplitude during the positive half cycle of the AC power supply │V AUX │; By the induced voltage V on the auxiliary winding when the PFC inductor L is magnetized AUX The absolute amplitude during the positive half cycle of the AC power supply │V AUX │Compare with the first inductor short-circuit protection threshold Vref1' to generate a positive half-cycle short-circuit detection result signal; by the induced voltage V on the auxiliary winding when the PFC inductor L is magnetized AUX The amplitude V during the negative half cycle of the AC power supply AUXThe negative half-cycle short-circuit detection result signal is compared with the second inductor short-circuit protection threshold Vref2' to generate a negative half-cycle short-circuit detection result signal; a PFC inductor short-circuit detection signal AUX_ZCD is generated by performing a logical OR operation on the positive half-cycle short-circuit detection result signal and the negative half-cycle short-circuit detection result signal; and a PFC inductor short-circuit detection signal AUX_ZCD is generated by performing a logical operation and / or timing on the PFC inductor short-circuit detection signal AUX_ZCD. It should be noted that due to the induced voltage V AUX The PFC inductor L oscillates at the beginning of magnetization, so it is usually based on the induced voltage V at the last falling edge of the positive half cycle or negative half cycle of the AC power supply AC, which is the PWM signal used to control the magnetization and demagnetization of the PFC inductor L. AUX To decide whether to enable or disable the PFC inductor short-circuit protection function.

[0041] Figure 9 Shown Figure 8 The schematic block diagram of the example logic structure of the inductor short circuit protection logic control and timing module is shown in FIG. Figure 9 As shown, in some embodiments, the PFC inductor short-circuit protection circuit 302 may be further configured to: generate a PFC inductor short-circuit determination signal by performing a logic operation and / or timing on the PFC inductor short-circuit detection signal AUX_ZCD; and generate a PFC inductor short-circuit protection signal by performing a logic AND operation on a signal portion of a PWM signal for controlling the magnetization and demagnetization of the PFC inductor L, which is used to control the magnetization of the PFC inductor L, and the PFC inductor short-circuit determination signal.

[0042] Figure 10 Shown Figure 3 The schematic block diagram of an example logic structure of a high-frequency bridge arm short-circuit protection circuit is shown in FIG. Figure 10 As shown, in some embodiments, the high-frequency bridge arm short-circuit protection circuit 304 can be configured as follows: ZCD The voltage V ZCD Perform negative voltage processing (for example, taking the absolute value, taking the opposite number, negative voltage clamping, etc.) to obtain the zero-crossing current detection resistor R ZCD The voltage V ZCD The absolute amplitude │V ZCD │; By connecting the zero-current detection resistor R ZCD The voltage V ZCD The absolute amplitude │V ZCD│Compared with the high-frequency bridge arm short-circuit protection threshold to generate a high-frequency bridge arm short-circuit detection signal; generating a high-frequency bridge arm short-circuit determination signal by performing a logical AND operation on the high-frequency bridge arm short-circuit detection signal and a leading-edge-blanked PWM signal, wherein the leading-edge-blanked PWM signal is generated by performing leading-edge blanking on the PWM signal used to control the on and off of the upper arm high-speed tube PWMH and the lower arm high-speed tube PWML; and generating a high-frequency bridge arm short-circuit protection signal by performing a logical operation and / or timing on the high-frequency bridge arm short-circuit determination signal.

[0043] In summary, the short-circuit protection circuit according to the embodiment of the present invention is based on the induced voltage V on the auxiliary winding of the PFC inductor L. AUX Perform PFC inductor short-circuit protection and / or zero-current detection based on the resistor R ZCD The voltage V ZCD The high-frequency bridge arm short-circuit protection function is implemented to effectively prevent the PFC inductor L from short-circuiting and damaging the circuit function of the totem pole PFC circuit, and avoid the reverse current loss of control caused by the short-circuit of the power tube of the high-frequency bridge arm, thereby reducing the maintenance cost of the PFC control chip and better ensuring the safety of the PFC control chip.

[0044] The present invention may be implemented in other specific forms without departing from its spirit and essential characteristics. For example, the algorithms described in the specific embodiments may be modified without departing from the basic spirit of the present invention. Therefore, the present embodiments are to be considered in all respects as illustrative and not restrictive, and the scope of the present invention is defined by the appended claims rather than the foregoing description. All modifications that come within the meaning and scope of the claims and equivalents are intended to be included within the scope of the present invention.

Claims

1. A short-circuit protection circuit for a totem pole PFC circuit, wherein: The totem pole PFC circuit includes a high-frequency bridge arm, a zero-crossing current detection resistor, and an output capacitor. When an upper arm high-speed transistor or a lower arm high-speed transistor of the high-frequency bridge arm is short-circuited, a discharge path of the output capacitor is from the upper plate of the output capacitor to the upper arm high-speed transistor, to the lower arm high-speed transistor, to the zero-crossing current detection resistor, and then to the lower plate of the output capacitor. The short-circuit protection circuit is configured to generate a high-frequency bridge arm short-circuit protection signal for disconnecting a main power line of the totem pole PFC circuit when the absolute amplitude of the voltage across the zero-crossing current detection resistor is less than a high-frequency bridge arm short-circuit protection threshold.

2. The short-circuit protection circuit according to claim 1, further configured as: Obtaining an absolute amplitude of the voltage on the zero-crossing current detection resistor by performing negative voltage processing on the voltage on the zero-crossing current detection resistor; generating a high-frequency bridge arm short-circuit detection signal by comparing the absolute amplitude of the voltage on the zero-crossing current detection resistor with the high-frequency bridge arm short-circuit protection threshold; A high-frequency bridge arm short-circuit determination signal is generated by performing a logic AND operation on the high-frequency bridge arm short-circuit detection signal and the pulse width modulation signal after leading edge blanking, wherein: The pulse width modulation signal with leading edge blanking is generated by performing leading edge blanking on the pulse width modulation signal for controlling the on and off of the upper arm high-speed tube and the lower arm high-speed tube; and The high-frequency bridge arm short-circuit protection signal is generated by performing logic operation and / or timing on the high-frequency bridge arm short-circuit determination signal.

3. The short-circuit protection circuit according to claim 1, wherein: The PFC circuit further includes a PFC inductor, and the short-circuit protection circuit is further configured as follows: When the absolute magnitude or amplitude of the induced voltage on the auxiliary winding of the PFC inductor during a positive half cycle of the AC power source is less than a first inductor short-circuit protection threshold, or when the absolute magnitude or amplitude of the induced voltage on the auxiliary winding of the PFC inductor during a negative half cycle of the AC power source is less than a second inductor short-circuit protection threshold, a PFC inductor short-circuit protection signal for disconnecting a main power line of the totem pole PFC circuit is generated.

4. The short-circuit protection circuit according to claim 3, further configured as: The absolute amplitude of the induced voltage on the auxiliary winding when the PFC inductor is demagnetized during the negative half cycle of the AC power supply is obtained by performing negative voltage processing on the induced voltage on the auxiliary winding when the PFC inductor is demagnetized during the negative half cycle of the AC power supply.

5. The short-circuit protection circuit according to claim 4, further configured as: generating a positive half-cycle short-circuit detection result signal by comparing the amplitude of the induced voltage on the auxiliary winding when the PFC inductor is demagnetized during the positive half-cycle of the AC power supply with the first inductor short-circuit protection threshold; generating a negative half-cycle short-circuit detection result signal by comparing an absolute amplitude of an induced voltage on the auxiliary winding when the PFC inductor is demagnetized during a negative half-cycle of the AC power supply with a second inductor short-circuit protection threshold; Generate a PFC inductor short circuit detection signal by performing a logical OR operation on the positive half-cycle short circuit detection result signal and the negative half-cycle short circuit detection result signal; and The PFC inductor short-circuit protection signal is generated by performing a logic operation and / or timing on the PFC inductor short-circuit detection signal.

6. The short-circuit protection circuit according to claim 5, further configured as: generating a de-jittered pulse width modulation signal by delaying a signal portion of a pulse width modulation signal for controlling magnetization and demagnetization of the PFC inductor, the signal portion being used to control demagnetization of the PFC inductor; Generate a PFC inductor short-circuit determination signal by performing logic operation and / or timing on the PFC inductor short-circuit detection signal; and The PFC inductor short-circuit protection signal is generated by performing a logic AND operation on the de-jittered pulse width modulation signal and the PFC inductor short-circuit determination signal.

7. The short-circuit protection circuit according to claim 3, further configured as: The absolute amplitude of the induced voltage on the auxiliary winding when the PFC inductor is magnetized during the positive half cycle of the AC power supply is obtained by performing negative voltage processing on the induced voltage on the auxiliary winding when the PFC inductor is magnetized during the positive half cycle of the AC power supply.

8. The short-circuit protection circuit according to claim 7, further configured as: generating a positive half-cycle short-circuit detection result signal by comparing an absolute amplitude of an induced voltage on the auxiliary winding when the PFC inductor is magnetized during a positive half-cycle of the AC power supply with the first inductor short-circuit protection threshold; generating a negative half-cycle short-circuit detection result signal by comparing the amplitude of the induced voltage on the auxiliary winding when the PFC inductor is magnetized during the negative half-cycle of the AC power supply with the second inductor short-circuit protection threshold; Generate a PFC inductor short circuit detection signal by performing a logical OR operation on the positive half-cycle short circuit detection result signal and the negative half-cycle short circuit detection result signal; and The PFC inductor short-circuit protection signal is generated by performing a logic operation and / or timing on the PFC inductor short-circuit detection signal.

9. The short-circuit protection circuit according to claim 8, further configured to: Generate a PFC inductor short-circuit determination signal by performing logic operation and / or timing on the PFC inductor short-circuit detection signal; and The PFC inductor short-circuit protection signal is generated by performing a logical AND operation on a signal portion of a pulse width modulation signal for controlling magnetization and demagnetization of the PFC inductor and the PFC inductor short-circuit determination signal.

10. A short-circuit protection circuit for a totem pole PFC circuit, wherein: The totem pole PFC circuit includes a PFC inductor, and the short-circuit protection circuit is configured as follows: When the absolute magnitude or amplitude of the induced voltage on the auxiliary winding of the PFC inductor during a positive half cycle of the AC power source is less than a first inductor short-circuit protection threshold, or when the absolute magnitude or amplitude of the induced voltage on the auxiliary winding of the PFC inductor during a negative half cycle of the AC power source is less than a second inductor short-circuit protection threshold, a PFC inductor short-circuit protection signal for disconnecting a main power line of the totem pole PFC circuit is generated.

11. The short-circuit protection circuit according to claim 10, further configured to: The absolute amplitude of the induced voltage on the auxiliary winding when the PFC inductor is demagnetized during the negative half cycle of the AC power supply is obtained by performing negative voltage processing on the induced voltage on the auxiliary winding when the PFC inductor is demagnetized during the negative half cycle of the AC power supply.

12. The short circuit protection circuit according to claim 11, further configured to: generating a positive half-cycle short-circuit detection result signal by comparing the amplitude of the induced voltage on the auxiliary winding when the PFC inductor is demagnetized during the positive half-cycle of the AC power supply with the first inductor short-circuit protection threshold; generating a negative half-cycle short-circuit detection result signal by comparing an absolute amplitude of an induced voltage on the auxiliary winding when the PFC inductor is demagnetized during a negative half-cycle of the AC power supply with a second inductor short-circuit protection threshold; Generate a PFC inductor short circuit detection signal by performing a logical OR operation on the positive half-cycle short circuit detection result signal and the negative half-cycle short circuit detection result signal; and The PFC inductor short-circuit protection signal is generated by performing a logic operation and / or timing on the PFC inductor short-circuit detection signal.

13. The short circuit protection circuit according to claim 14, further configured to: generating a de-jittered pulse width modulation signal by delaying a signal portion of a pulse width modulation signal for controlling magnetization and demagnetization of the PFC inductor, the signal portion being used to control demagnetization of the PFC inductor; Generate a PFC inductor short-circuit determination signal by performing logic operation and / or timing on the PFC inductor short-circuit detection signal; and The PFC inductor short-circuit protection signal is generated by performing a logic AND operation on the de-jittered pulse width modulation signal and the PFC inductor short-circuit determination signal.

14. The short circuit protection circuit according to claim 10, further configured to: The absolute amplitude of the induced voltage on the auxiliary winding when the PFC inductor is magnetized during the positive half cycle of the AC power supply is obtained by performing negative voltage processing on the induced voltage on the auxiliary winding when the PFC inductor is magnetized during the positive half cycle of the AC power supply.

15. The short circuit protection circuit according to claim 14, further configured to: generating a positive half-cycle short-circuit detection result signal by comparing an absolute amplitude of an induced voltage on the auxiliary winding when the PFC inductor is magnetized during a positive half-cycle of the AC power supply with the first inductor short-circuit protection threshold; generating a negative half-cycle short-circuit detection result signal by comparing the amplitude of the induced voltage on the auxiliary winding when the PFC inductor is magnetized during the negative half-cycle of the AC power supply with the second inductor short-circuit protection threshold; Generate a PFC inductor short circuit detection signal by performing a logical OR operation on the positive half-cycle short circuit detection result signal and the negative half-cycle short circuit detection result signal; and The PFC inductor short-circuit protection signal is generated by performing a logic operation and / or timing on the PFC inductor short-circuit detection signal.

16. The short circuit protection circuit according to claim 15, further configured to: Generate a PFC inductor short-circuit determination signal by performing logic operation and / or timing on the PFC inductor short-circuit detection signal; and The PFC inductor short-circuit protection signal is generated by performing a logical AND operation on a signal portion of a pulse width modulation signal for controlling magnetization and demagnetization of the PFC inductor and the PFC inductor short-circuit determination signal.

17. A totem pole PFC circuit, comprising the short-circuit protection circuit according to any one of claims 1 to 16.

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